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0808.2379
Ujjal Debnath
Ujjal Debnath
Emergent Universe and Phantom Tachyon Model
7 Latex pages, 7 figures, RevTex style
Class.Quant.Grav.25:205019,2008
10.1088/0264-9381/25/20/205019
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this work, I have considered that the universe is filled with normal matter and phantom field (or tachyonic field). If the universe is filled with scalar field, Ellis et al have shown that emergent scenario is possible only for $k=+1$ i.e. for closed universe and here I have shown that the emergent scenario is possible for closed universe if the universe contains normal tachyonic field. But for phantom field (or tachyonic field), the negative kinetic term can generate the emergent scenario for all values of $k ~(=0,\pm 1)$. From recently developed statefinder parameters, the behaviour of different stages of the evolution of the emergent universe have been studied. The static Einstein universe and the stability analysis have been briefly discussed for both phantom and tachyon models.
[ { "created": "Mon, 18 Aug 2008 12:35:58 GMT", "version": "v1" } ]
2008-11-26
[ [ "Debnath", "Ujjal", "" ] ]
In this work, I have considered that the universe is filled with normal matter and phantom field (or tachyonic field). If the universe is filled with scalar field, Ellis et al have shown that emergent scenario is possible only for $k=+1$ i.e. for closed universe and here I have shown that the emergent scenario is possible for closed universe if the universe contains normal tachyonic field. But for phantom field (or tachyonic field), the negative kinetic term can generate the emergent scenario for all values of $k ~(=0,\pm 1)$. From recently developed statefinder parameters, the behaviour of different stages of the evolution of the emergent universe have been studied. The static Einstein universe and the stability analysis have been briefly discussed for both phantom and tachyon models.
1005.3009
Krzysztof Bolejko
Krzysztof Bolejko, William R. Stoeger
Conditions for spontaneous homogenization of the Universe
7 pages. Fifth Award in the 2010 Gravity Research Foundation essay competition
Gen.Rel.Grav.42:2349-2356,2010
10.1007/s10714-010-1020-6 10.1142/S0218271810018566
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The present-day Universe appears to be homogeneous on very large scales. Yet when the casual structure of the early Universe is considered, it becomes apparent that the early Universe must have been highly inhomogeneous. The current paradigm attempts to answer this problem by postulating the inflation mechanism However, inflation in order to start requires a homogeneous patch of at least the horizon size. This paper examines if dynamical processes of the early Universe could lead to homogenization. In the past similar studies seem to imply that the set of initial conditions that leads to homogenization is of measure zero. This essay proves contrary: a set of initial conditions for spontaneous homogenization of cosmological models can form a set of non-zero measure.
[ { "created": "Mon, 17 May 2010 19:48:48 GMT", "version": "v1" } ]
2011-03-04
[ [ "Bolejko", "Krzysztof", "" ], [ "Stoeger", "William R.", "" ] ]
The present-day Universe appears to be homogeneous on very large scales. Yet when the casual structure of the early Universe is considered, it becomes apparent that the early Universe must have been highly inhomogeneous. The current paradigm attempts to answer this problem by postulating the inflation mechanism However, inflation in order to start requires a homogeneous patch of at least the horizon size. This paper examines if dynamical processes of the early Universe could lead to homogenization. In the past similar studies seem to imply that the set of initial conditions that leads to homogenization is of measure zero. This essay proves contrary: a set of initial conditions for spontaneous homogenization of cosmological models can form a set of non-zero measure.
0807.3226
Yun-Song Piao
Yun-Song Piao
On Primordial Density Perturbation and Decaying Speed of Sound
3 pages, 2 eps figure, contents extended, refs. added, published version,
Phys.Rev.D79:067301,2009
10.1103/PhysRevD.79.067301
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The decaying speed of sound can lead to the emergence of the primordial density perturbation in any expanding phase, even if the expansion is decelerated. Recently, some proposals have been given to implement this mechanism, in which it was found that the primordial spectrum of scalar perturbation can be scale invariant. In this note, we will give more insights for the details of this seeding mechanism.
[ { "created": "Mon, 21 Jul 2008 09:58:27 GMT", "version": "v1" }, { "created": "Sat, 28 Mar 2009 02:58:09 GMT", "version": "v2" } ]
2009-11-06
[ [ "Piao", "Yun-Song", "" ] ]
The decaying speed of sound can lead to the emergence of the primordial density perturbation in any expanding phase, even if the expansion is decelerated. Recently, some proposals have been given to implement this mechanism, in which it was found that the primordial spectrum of scalar perturbation can be scale invariant. In this note, we will give more insights for the details of this seeding mechanism.
2304.07952
Chen Wu
Zening Yan, Xiaoji Zhang, Maoyuan Wan, and Chen Wu
Shadows and quasinormal modes of a charged non-commutative black hole by different methods
25 pages, 12 figures
European Physical Journal Plus (2023) 138:377
10.1140/epjp/s13360-023-03978-3
null
gr-qc
http://creativecommons.org/licenses/by-sa/4.0/
In this paper, we calculated the quasinormal modes (QNMs) of a charged non-commutative black hole in scalar, electromagnetic and gravitational fields by three methods. We gave the influence of non-commutative parameter $\theta$ and charge $Q$ on QNMs in different fields. Thereafter, we calculated the shadow radius of the black hole and provided the valid range of $\theta$ and $Q$ using the constraints on the shadow radius of $\text{M87}^{\ast}$ and $\text{Sgr A}^{\ast}$ from the Event Horizon Telescope (EHT). In addition, we estimated the ``relative deviation'' of the shadow radius ($\delta_{R_{s}}$) between non-commutative spacetime and commutative spacetime. We found that the maximum values of $\delta_{R_{s}}$ decreases with the increase of charge $Q$. In other words, the non-commutativity of spacetime becomes harder to distinguish as the charge of the black hole increases.
[ { "created": "Mon, 17 Apr 2023 02:34:50 GMT", "version": "v1" } ]
2023-05-12
[ [ "Yan", "Zening", "" ], [ "Zhang", "Xiaoji", "" ], [ "Wan", "Maoyuan", "" ], [ "Wu", "Chen", "" ] ]
In this paper, we calculated the quasinormal modes (QNMs) of a charged non-commutative black hole in scalar, electromagnetic and gravitational fields by three methods. We gave the influence of non-commutative parameter $\theta$ and charge $Q$ on QNMs in different fields. Thereafter, we calculated the shadow radius of the black hole and provided the valid range of $\theta$ and $Q$ using the constraints on the shadow radius of $\text{M87}^{\ast}$ and $\text{Sgr A}^{\ast}$ from the Event Horizon Telescope (EHT). In addition, we estimated the ``relative deviation'' of the shadow radius ($\delta_{R_{s}}$) between non-commutative spacetime and commutative spacetime. We found that the maximum values of $\delta_{R_{s}}$ decreases with the increase of charge $Q$. In other words, the non-commutativity of spacetime becomes harder to distinguish as the charge of the black hole increases.
2403.04695
Yuri Pavlov
A. A. Grib, Yu. V. Pavlov
On phase transitions during collisions near the horizon of black holes
12 pages
Universe 2024, 10, 131
10.3390/universe10030131
null
gr-qc astro-ph.HE hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
During particle collisions in the vicinity of the horizon of black holes, it is possible to achieve energies and temperatures corresponding to phase transitions in particle physics. It is shown that the sizes of the regions of the new phase are of the order of the Compton length for the corresponding mass scale. The lifetime is also on the order of the Compton time. It is shown that the inverse influence of the energy density in the electro-weak phase transition in collisions on the space-time metric can be neglected.
[ { "created": "Thu, 7 Mar 2024 17:44:07 GMT", "version": "v1" } ]
2024-03-08
[ [ "Grib", "A. A.", "" ], [ "Pavlov", "Yu. V.", "" ] ]
During particle collisions in the vicinity of the horizon of black holes, it is possible to achieve energies and temperatures corresponding to phase transitions in particle physics. It is shown that the sizes of the regions of the new phase are of the order of the Compton length for the corresponding mass scale. The lifetime is also on the order of the Compton time. It is shown that the inverse influence of the energy density in the electro-weak phase transition in collisions on the space-time metric can be neglected.
gr-qc/0005096
Joseph Samuel
Joseph Samuel and Rajaram Nityananda
Transport along Null Curves
Latex 17 pages, no figures
J.Phys.A33:2895,2000
10.1088/0305-4470/33/14/318
null
gr-qc
null
Fermi Transport is useful for describing the behaviour of spins or gyroscopes following non-geodesic, timelike world lines. However, Fermi Transport breaks down for null world lines. We introduce a transport law for polarisation vectors along non-geodesic null curves. We show how this law emerges naturally from the geometry of null directions by comparing polarisation vectors associated with two distinct null directions. We then give a spinorial treatment of this topic and make contact with the geometric phase of quantum mechanics. There are two significant differences between the null and timelike cases. In the null case (i) The transport law does not approach a unique smooth limit as the null curve approaches a null geodesic. (ii) The transport law for vectors is integrable, i.e the result depends only on the local properties of the curve and not on the entire path taken. However, the transport of spinors is not integrable: there is a global sign of topological origin.
[ { "created": "Mon, 22 May 2000 08:41:42 GMT", "version": "v1" } ]
2008-11-26
[ [ "Samuel", "Joseph", "" ], [ "Nityananda", "Rajaram", "" ] ]
Fermi Transport is useful for describing the behaviour of spins or gyroscopes following non-geodesic, timelike world lines. However, Fermi Transport breaks down for null world lines. We introduce a transport law for polarisation vectors along non-geodesic null curves. We show how this law emerges naturally from the geometry of null directions by comparing polarisation vectors associated with two distinct null directions. We then give a spinorial treatment of this topic and make contact with the geometric phase of quantum mechanics. There are two significant differences between the null and timelike cases. In the null case (i) The transport law does not approach a unique smooth limit as the null curve approaches a null geodesic. (ii) The transport law for vectors is integrable, i.e the result depends only on the local properties of the curve and not on the entire path taken. However, the transport of spinors is not integrable: there is a global sign of topological origin.
1007.3299
John Ward
Paulo Vargas Moniz and John Ward
Gauge field back-reaction in Born Infeld cosmologies
34 pages, 3 figures. Minor clarifications. References added
Class.Quant.Grav.27:235009,2010
10.1088/0264-9381/27/23/235009
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper, we investigate the back-reaction of $U(1)$ gauge fields into a class of inflationary settings. To be more precise, we employ a Bianchi-I geometry (taken as an anisotropic perturbation of a flat FRW model) within two types of Born-Infeld theories. Firstly we consider pure Born-Infeld electromagnetism. For either a constant or a $b(\phi)$ coupling, inflationary trajectories are modified but anisotropies increase; In particular, for the former coupling we find that a quadratic inflaton potential, within a constant ratio for the scalar and gauge energy densities, does not induce sufficient inflation, while in the latter the back-reaction in the cosmology determines (from the tensor-scalar ratio) a narrow range where inflation can occur. A Dirac-Born-Infeld framework is afterwards analysed in both non-relativistic and relativistic regimes. In the former, for different cases of the coupling (richer with respect to mere BI setups) between scalar and gauge sectors, we find that inflationary trajectories are modified, with anisotropy increasing or decreasing. In particular, a tachyonic solution is studied, allowing for a non standard ratio between scalar and gauge matter densities, enhancing sufficient inflation, but with the anisotropy increasing. For the relativistic limit, inflationary trajectories are also modified and anisotropies increase faster than in the non-relativistic limit. Finally we discuss how magnetic seed fields could evolve in these settings.
[ { "created": "Mon, 19 Jul 2010 22:27:33 GMT", "version": "v1" }, { "created": "Mon, 9 Aug 2010 17:57:59 GMT", "version": "v2" } ]
2011-03-28
[ [ "Moniz", "Paulo Vargas", "" ], [ "Ward", "John", "" ] ]
In this paper, we investigate the back-reaction of $U(1)$ gauge fields into a class of inflationary settings. To be more precise, we employ a Bianchi-I geometry (taken as an anisotropic perturbation of a flat FRW model) within two types of Born-Infeld theories. Firstly we consider pure Born-Infeld electromagnetism. For either a constant or a $b(\phi)$ coupling, inflationary trajectories are modified but anisotropies increase; In particular, for the former coupling we find that a quadratic inflaton potential, within a constant ratio for the scalar and gauge energy densities, does not induce sufficient inflation, while in the latter the back-reaction in the cosmology determines (from the tensor-scalar ratio) a narrow range where inflation can occur. A Dirac-Born-Infeld framework is afterwards analysed in both non-relativistic and relativistic regimes. In the former, for different cases of the coupling (richer with respect to mere BI setups) between scalar and gauge sectors, we find that inflationary trajectories are modified, with anisotropy increasing or decreasing. In particular, a tachyonic solution is studied, allowing for a non standard ratio between scalar and gauge matter densities, enhancing sufficient inflation, but with the anisotropy increasing. For the relativistic limit, inflationary trajectories are also modified and anisotropies increase faster than in the non-relativistic limit. Finally we discuss how magnetic seed fields could evolve in these settings.
1106.3734
Daniele Malafarina
Daniele Malafarina and Pankaj S. Joshi
Thermodynamics and gravitational collapse
8 pages, 2 figures
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
It is known now that a typical gravitational collapse in general relativity, evolving from regular initial data and under physically reasonable conditions would end in either a black hole or a naked singularity final state. An important question that needs to be answered in this connection is, whether the analogues of the laws of thermodynamics, as formulated for relativistic horizons are respected by the dynamical spacetimes for collapse that end in the formation of a naked singularity. We investigate here the thermodynamical behaviour of the dynamical horizons that form in spherically symmetric gravitational collapse and we show that the first and second laws of black hole thermodynamics, as extended to dynamical spacetimes in a suitable manner, are not violated whether the collapse ends in a black hole or a naked singularity. We then make a distinction between the naked singularities that result from gravitational collapse, and those that exist in solutions of Einstein equations in vacuum axially symmetric and stationary spacetimes, and discuss their connection with thermodynamics in view of the cosmic censorship conjecture and the validity of the third law of black hole mechanics.
[ { "created": "Sun, 19 Jun 2011 11:14:00 GMT", "version": "v1" } ]
2011-06-21
[ [ "Malafarina", "Daniele", "" ], [ "Joshi", "Pankaj S.", "" ] ]
It is known now that a typical gravitational collapse in general relativity, evolving from regular initial data and under physically reasonable conditions would end in either a black hole or a naked singularity final state. An important question that needs to be answered in this connection is, whether the analogues of the laws of thermodynamics, as formulated for relativistic horizons are respected by the dynamical spacetimes for collapse that end in the formation of a naked singularity. We investigate here the thermodynamical behaviour of the dynamical horizons that form in spherically symmetric gravitational collapse and we show that the first and second laws of black hole thermodynamics, as extended to dynamical spacetimes in a suitable manner, are not violated whether the collapse ends in a black hole or a naked singularity. We then make a distinction between the naked singularities that result from gravitational collapse, and those that exist in solutions of Einstein equations in vacuum axially symmetric and stationary spacetimes, and discuss their connection with thermodynamics in view of the cosmic censorship conjecture and the validity of the third law of black hole mechanics.
gr-qc/0305084
Matteo Luca Ruggiero
Guido Rizzi, Matteo Luca Ruggiero
The relativistic Sagnac Effect: two derivations
49 pages, LaTeX, 3 EPS figures. Revised (final) version, minor corrections; to appear in "Relativity in Rotating Frames", ed. G. Rizzi and M.L. Ruggiero, Kluwer Academic Publishers, Dordrecht, (2003). See also http://digilander.libero.it/solciclos
null
null
null
gr-qc
null
The phase shift due to the Sagnac Effect, for relativistic matter and electromagnetic beams, counter-propagating in a rotating interferometer, is deduced using two different approaches. From one hand, we show that the relativistic law of velocity addition leads to the well known Sagnac time difference, which is the same independently of the physical nature of the interfering beams, evidencing in this way the universality of the effect. Another derivation is based on a formal analogy with the phase shift induced by the magnetic potential for charged particles travelling in a region where a constant vector potential is present: this is the so called Aharonov-Bohm effect. Both derivations are carried out in a fully relativistic context, using a suitable 1+3 splitting that allows us to recognize and define the space where electromagnetic and matter waves propagate: this is an extended 3-space, which we call "relative space". It is recognized as the only space having an actual physical meaning from an operational point of view, and it is identified as the 'physical space of the rotating platform': the geometry of this space turns out to be non Euclidean, according to Einstein's early intuition.
[ { "created": "Thu, 22 May 2003 10:38:30 GMT", "version": "v1" }, { "created": "Fri, 18 Jul 2003 15:34:27 GMT", "version": "v2" }, { "created": "Thu, 25 Sep 2003 13:51:29 GMT", "version": "v3" }, { "created": "Fri, 26 Sep 2003 09:31:16 GMT", "version": "v4" } ]
2007-05-23
[ [ "Rizzi", "Guido", "" ], [ "Ruggiero", "Matteo Luca", "" ] ]
The phase shift due to the Sagnac Effect, for relativistic matter and electromagnetic beams, counter-propagating in a rotating interferometer, is deduced using two different approaches. From one hand, we show that the relativistic law of velocity addition leads to the well known Sagnac time difference, which is the same independently of the physical nature of the interfering beams, evidencing in this way the universality of the effect. Another derivation is based on a formal analogy with the phase shift induced by the magnetic potential for charged particles travelling in a region where a constant vector potential is present: this is the so called Aharonov-Bohm effect. Both derivations are carried out in a fully relativistic context, using a suitable 1+3 splitting that allows us to recognize and define the space where electromagnetic and matter waves propagate: this is an extended 3-space, which we call "relative space". It is recognized as the only space having an actual physical meaning from an operational point of view, and it is identified as the 'physical space of the rotating platform': the geometry of this space turns out to be non Euclidean, according to Einstein's early intuition.
2206.11734
Nikolaos Mavromatos
Nikos Chatzifotis, Panos Dorlis, Nick E. Mavromatos and Eleftherios Papantonopoulos
Axion induced angular momentum reversal in Kerr-like black holes
13 pages revtex, 7 pdf figures incorporated
null
10.1103/PhysRevD.106.084002
KCL-PH-TH/2022-37
gr-qc astro-ph.HE hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We consider a pseudoscalar axion-like field coupled to a Chern-Simons gravitational anomaly term. The axion field backreacts on a rotating Kerr black hole background, resulting in modifications in the spacetime. In an attempt to determine potentially observable signatures, we study the angular momentum of the system of the modified Kerr-like black hole and the axionic matter outside the horizon of the black hole. As the strength of the coupling of the axion field to the Chern-Simons term is increasing, the requirement that the total angular momentum of the system remain constant forces the black hole angular momentum to decrease. There exists a critical value of this coupling beyond which the black hole starts to rotate in the opposite direction, with an increasing magnitude of its angular momentum. We interpret this effect as a consequence of the exchange of energy between the axionic matter and the gravitational anomaly, which is sourced by the rotating black hole.
[ { "created": "Thu, 23 Jun 2022 14:30:08 GMT", "version": "v1" } ]
2022-10-19
[ [ "Chatzifotis", "Nikos", "" ], [ "Dorlis", "Panos", "" ], [ "Mavromatos", "Nick E.", "" ], [ "Papantonopoulos", "Eleftherios", "" ] ]
We consider a pseudoscalar axion-like field coupled to a Chern-Simons gravitational anomaly term. The axion field backreacts on a rotating Kerr black hole background, resulting in modifications in the spacetime. In an attempt to determine potentially observable signatures, we study the angular momentum of the system of the modified Kerr-like black hole and the axionic matter outside the horizon of the black hole. As the strength of the coupling of the axion field to the Chern-Simons term is increasing, the requirement that the total angular momentum of the system remain constant forces the black hole angular momentum to decrease. There exists a critical value of this coupling beyond which the black hole starts to rotate in the opposite direction, with an increasing magnitude of its angular momentum. We interpret this effect as a consequence of the exchange of energy between the axionic matter and the gravitational anomaly, which is sourced by the rotating black hole.
0712.0683
Ghanashyam Date
Kinjal Banerjee and Ghanashyam Date
Loop Quantization of Polarized Gowdy Model on $T^3$: Classical Theory
20 pages, no figures. Final version; to appear in Classical and Quantum Gravity. Additional References included
Class.Quant.Grav.25:105014,2008
10.1088/0264-9381/25/10/105014
IMSc/2007/12/15
gr-qc hep-th
null
The vacuum Gowdy models provide much studied, non-trivial midi-superspace examples. Various technical issues within Loop Quantum Gravity can be studied in these models as well as one can hope to understand singularities and their resolution in the loop quantization. The first step in this program is to reformulate the model in real connection variables in a manner that is amenable to loop quantization. We begin with the unpolarized model and carry out a consistent reduction to the polarized case. Carrying out complete gauge fixing, the known solutions are recovered.
[ { "created": "Wed, 5 Dec 2007 10:53:38 GMT", "version": "v1" }, { "created": "Thu, 17 Apr 2008 12:31:03 GMT", "version": "v2" } ]
2008-11-26
[ [ "Banerjee", "Kinjal", "" ], [ "Date", "Ghanashyam", "" ] ]
The vacuum Gowdy models provide much studied, non-trivial midi-superspace examples. Various technical issues within Loop Quantum Gravity can be studied in these models as well as one can hope to understand singularities and their resolution in the loop quantization. The first step in this program is to reformulate the model in real connection variables in a manner that is amenable to loop quantization. We begin with the unpolarized model and carry out a consistent reduction to the polarized case. Carrying out complete gauge fixing, the known solutions are recovered.
1909.08271
Oscar Alejandro Reula
A. L. Garc\'ia-Perciante and Oscar. Reula
On the illposedness and stability of the relativistic heat equation
5 pages
null
10.1063/1.5123393
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this note we analyze, in terms of a simple example, the incompatibility of parabolic evolution and general covariance. For this we introduce a unit time-like four-vector and study the simplest heat flux equation with respect to it. In cases where this vector field is surface forming then the local high wave number limit shows well posedness, but as soon as that property is lost the Cauchy problem becomes ill-posed. We also discuss how the Maxwell-Cattaneo type modification of the system renders it well posed and link the amplitude of the modification, which is related to the so-called second wave speed of the system, to the size of the failure of surface orthogonality.
[ { "created": "Wed, 18 Sep 2019 07:40:19 GMT", "version": "v1" } ]
2020-06-24
[ [ "García-Perciante", "A. L.", "" ], [ "Reula", "Oscar.", "" ] ]
In this note we analyze, in terms of a simple example, the incompatibility of parabolic evolution and general covariance. For this we introduce a unit time-like four-vector and study the simplest heat flux equation with respect to it. In cases where this vector field is surface forming then the local high wave number limit shows well posedness, but as soon as that property is lost the Cauchy problem becomes ill-posed. We also discuss how the Maxwell-Cattaneo type modification of the system renders it well posed and link the amplitude of the modification, which is related to the so-called second wave speed of the system, to the size of the failure of surface orthogonality.
1701.00134
Gabriel Farrugia
Gabriel Farrugia and Jackson Levi Said
Stability of the flat FLRW metric in $f(T)$ gravity
14 pages, 14 figures
Phys. Rev. D 94, 124054 (2016)
10.1103/PhysRevD.94.124054
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper, we investigate the stability of the flat FLRW metric in $f(T)$ gravity. This is achieved by analysing the small perturbations, $\delta$ about the Hubble parameter and the matter energy density, $\delta_\text{m}$. We find that $\delta \propto \dot{H}/H$ and $\delta_{\text{m}} \propto H$. Since the Hubble parameter depends on the function $f(T)$, two models were considered (A) the power-law model $f(T) = \alpha (-T)^n$, and (B) the exponential model $f(T) = \alpha T_0 \left(1 - \exp \left[-p \sqrt{\dfrac{T}{T_0}}\right]\right)$, where the parameters $n$ and $p$ were chosen to give comparable physical results. For the parameters considered, it was found that the solutions are stable with vanishing $\delta$ and decaying then constant $\delta_{\text{m}}$, meaning that the matter perturbations persist during late times.
[ { "created": "Sat, 31 Dec 2016 16:27:24 GMT", "version": "v1" } ]
2017-01-03
[ [ "Farrugia", "Gabriel", "" ], [ "Said", "Jackson Levi", "" ] ]
In this paper, we investigate the stability of the flat FLRW metric in $f(T)$ gravity. This is achieved by analysing the small perturbations, $\delta$ about the Hubble parameter and the matter energy density, $\delta_\text{m}$. We find that $\delta \propto \dot{H}/H$ and $\delta_{\text{m}} \propto H$. Since the Hubble parameter depends on the function $f(T)$, two models were considered (A) the power-law model $f(T) = \alpha (-T)^n$, and (B) the exponential model $f(T) = \alpha T_0 \left(1 - \exp \left[-p \sqrt{\dfrac{T}{T_0}}\right]\right)$, where the parameters $n$ and $p$ were chosen to give comparable physical results. For the parameters considered, it was found that the solutions are stable with vanishing $\delta$ and decaying then constant $\delta_{\text{m}}$, meaning that the matter perturbations persist during late times.
1510.08585
Lorenzo Iorio
Lorenzo Iorio
The impact of the orbital decay of the LAGEOS satellites on the frame-dragging tests
LaTex2e, 2 tables, 1 figure, 12 pages. At press in Advances in Space Research (ASR)
Adv.Space Res.57:493-498,2016
10.1016/j.asr.2015.10.014
null
gr-qc astro-ph.EP physics.geo-ph physics.space-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The laser-tracked geodetic satellites LAGEOS, LAGEOS II and LARES are currently employed, among other things, to measure the general relativistic Lense-Thirring effect in the gravitomagnetic field of the spinning Earth with the hope of providing a more accurate test of such a prediction of the Einstein's theory of gravitation than the existing ones. The secular decay $\dot a$ of the semimajor axes $a$ of such spacecrafts, recently measured in an independent way to a $\sigma_{\dot a}\approx 0.1-0.01$ m yr$^{-1}$ accuracy level, may indirectly impact the proposed relativistic experiment through its connection with the classical orbital precessions induced by the Earth's oblateness $J_2$. \textcolor{black}{Indeed,} the systematic bias due to the current measurement errors $\sigma_{\dot a}$ is of the same order of magnitude of, or even larger than, the expected relativistic signal itself; moreover, it grows linearly with the time span $T$ of the analysis. \textcolor{black}{Therefore, the parameter-fitting algorithms must be properly updated in order to suitably cope with such a new source of systematic uncertainty. Otherwise,} an improvement of one-two orders of magnitude in measuring the orbital decay of the satellites of the LAGEOS family would be required to reduce this source of systematic uncertainty to a percent fraction of the Lense-Thirring signature.
[ { "created": "Thu, 29 Oct 2015 07:33:26 GMT", "version": "v1" } ]
2015-12-15
[ [ "Iorio", "Lorenzo", "" ] ]
The laser-tracked geodetic satellites LAGEOS, LAGEOS II and LARES are currently employed, among other things, to measure the general relativistic Lense-Thirring effect in the gravitomagnetic field of the spinning Earth with the hope of providing a more accurate test of such a prediction of the Einstein's theory of gravitation than the existing ones. The secular decay $\dot a$ of the semimajor axes $a$ of such spacecrafts, recently measured in an independent way to a $\sigma_{\dot a}\approx 0.1-0.01$ m yr$^{-1}$ accuracy level, may indirectly impact the proposed relativistic experiment through its connection with the classical orbital precessions induced by the Earth's oblateness $J_2$. \textcolor{black}{Indeed,} the systematic bias due to the current measurement errors $\sigma_{\dot a}$ is of the same order of magnitude of, or even larger than, the expected relativistic signal itself; moreover, it grows linearly with the time span $T$ of the analysis. \textcolor{black}{Therefore, the parameter-fitting algorithms must be properly updated in order to suitably cope with such a new source of systematic uncertainty. Otherwise,} an improvement of one-two orders of magnitude in measuring the orbital decay of the satellites of the LAGEOS family would be required to reduce this source of systematic uncertainty to a percent fraction of the Lense-Thirring signature.
1709.07154
Elias C. Vagenas
Saurya Das, Matthew P. G. Robbins, Elias C. Vagenas
Gravitation as a source of decoherence
7 pages, REVTeX 4, no figures, to appear in IJMPD
Int. J. Mod. Phys. D 27, No. 01 (2018) 1850008
10.1142/S0218271818500086
null
gr-qc hep-th quant-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
It is believed that classical behavior emerges in a quantum system due to decoherence. It has also been proposed that gravity can be a source of this decoherence. We examine this in detail by studying a number of quantum systems, including ultra-relativistic and non-relativistic particles, at low and high temperatures in an expanding Universe, and show that this proposal is valid for a large class of quantum systems.
[ { "created": "Thu, 21 Sep 2017 04:45:09 GMT", "version": "v1" } ]
2017-10-31
[ [ "Das", "Saurya", "" ], [ "Robbins", "Matthew P. G.", "" ], [ "Vagenas", "Elias C.", "" ] ]
It is believed that classical behavior emerges in a quantum system due to decoherence. It has also been proposed that gravity can be a source of this decoherence. We examine this in detail by studying a number of quantum systems, including ultra-relativistic and non-relativistic particles, at low and high temperatures in an expanding Universe, and show that this proposal is valid for a large class of quantum systems.
1809.02127
Ilia Musco
Ilia Musco
Threshold for primordial black holes: Dependence on the shape of the cosmological perturbations
18 pages, 5 figures. The paper has been selected by Physical Review D as an Editors' Suggestion
Phys. Rev. D 100, 123524 (2019)
10.1103/PhysRevD.100.123524
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Primordial black holes may have formed in the radiative era of the early Universe from the collapse of large enough amplitude perturbations of the metric. These correspond to non linear energy density perturbations characterized by an amplitude larger than a certain threshold, measured when the perturbations reenter the cosmological horizon. The process of primordial black hole formation is studied here within spherical symmetry, using the gradient expansion approximation in the long wavelength limit, where the pressure gradients are small, and the initial perturbations are functions only of a time-independent curvature profile. In this regime it is possible to understand how the threshold for primordial black hole formation depends on the shape of the initial energy density profile, clarifying the relation between local and averaged measures of the perturbation amplitude. Although there is no universal threshold for primordial black hole formation, the averaged mass excess of the perturbation depends on the amplitude of the energy density peak, and it is possible to formulate a well-defined criterion to establish when a cosmological perturbation is able to form a black hole in terms of one of these two key quantities. This gives understanding of how the abundance of primordial black holes depends on the shape of the the inflationary power spectrum of cosmological perturbations.
[ { "created": "Thu, 6 Sep 2018 17:58:21 GMT", "version": "v1" }, { "created": "Tue, 29 Oct 2019 01:50:33 GMT", "version": "v2" }, { "created": "Fri, 3 Jan 2020 18:49:46 GMT", "version": "v3" } ]
2020-01-06
[ [ "Musco", "Ilia", "" ] ]
Primordial black holes may have formed in the radiative era of the early Universe from the collapse of large enough amplitude perturbations of the metric. These correspond to non linear energy density perturbations characterized by an amplitude larger than a certain threshold, measured when the perturbations reenter the cosmological horizon. The process of primordial black hole formation is studied here within spherical symmetry, using the gradient expansion approximation in the long wavelength limit, where the pressure gradients are small, and the initial perturbations are functions only of a time-independent curvature profile. In this regime it is possible to understand how the threshold for primordial black hole formation depends on the shape of the initial energy density profile, clarifying the relation between local and averaged measures of the perturbation amplitude. Although there is no universal threshold for primordial black hole formation, the averaged mass excess of the perturbation depends on the amplitude of the energy density peak, and it is possible to formulate a well-defined criterion to establish when a cosmological perturbation is able to form a black hole in terms of one of these two key quantities. This gives understanding of how the abundance of primordial black holes depends on the shape of the the inflationary power spectrum of cosmological perturbations.
gr-qc/0101057
Rodolfo Gambini
Rodolfo Gambini and Rafael A. Porto
Relational time in generally covariant quantum systems: four models
18 pages, revtex file
Phys.Rev. D63 (2001) 105014
10.1103/PhysRevD.63.105014
IFFC-01-01
gr-qc
null
We analize the relational quantum evolution of generally covariant systems in terms of Rovelli's evolving constants of motion and the generalized Heisenberg picture. In order to have a well defined evolution, and a consistent quantum theory, evolving constants must be self-adjoint operators. We show that this condition imposes strong restrictions to the choices of the clock variables. We analize four cases. The first one is non- relativistic quantum mechanics in parametrized form. We show that, for the free particle case, the standard choice of time is the only one leading to self-adjoint evolving constants. Secondly, we study the relativistic case. We show that the resulting quantum theory is the free particle representation of the Klein Gordon equation in which the position is a perfectly well defined quantum observable. The admissible choices of clock variables are the ones leading to space-like simultaneity surfaces. In order to mimic the structure of General Relativity we study the SL(2R) model with two Hamiltonian constraints. The evolving constants depend in this case on three independent variables. We show that it is possible to find clock variables and inner products leading to a consistent quantum theory. Finally, we discuss the quantization of a constrained model having a compact constraint surface. All the models considered may be consistently quantized, although some of them do not admit any time choice such that the equal time surfaces are transversal to the orbits.
[ { "created": "Mon, 15 Jan 2001 13:30:10 GMT", "version": "v1" } ]
2009-11-07
[ [ "Gambini", "Rodolfo", "" ], [ "Porto", "Rafael A.", "" ] ]
We analize the relational quantum evolution of generally covariant systems in terms of Rovelli's evolving constants of motion and the generalized Heisenberg picture. In order to have a well defined evolution, and a consistent quantum theory, evolving constants must be self-adjoint operators. We show that this condition imposes strong restrictions to the choices of the clock variables. We analize four cases. The first one is non- relativistic quantum mechanics in parametrized form. We show that, for the free particle case, the standard choice of time is the only one leading to self-adjoint evolving constants. Secondly, we study the relativistic case. We show that the resulting quantum theory is the free particle representation of the Klein Gordon equation in which the position is a perfectly well defined quantum observable. The admissible choices of clock variables are the ones leading to space-like simultaneity surfaces. In order to mimic the structure of General Relativity we study the SL(2R) model with two Hamiltonian constraints. The evolving constants depend in this case on three independent variables. We show that it is possible to find clock variables and inner products leading to a consistent quantum theory. Finally, we discuss the quantization of a constrained model having a compact constraint surface. All the models considered may be consistently quantized, although some of them do not admit any time choice such that the equal time surfaces are transversal to the orbits.
gr-qc/9806011
Heller Michal
M. Heller (Vatican Observatory), W. Sasin (Institute of Mathematics, Warsaw University of Technology)
Einstein-Podolski-Rosen Experiment from Noncommutative Quantum Gravity
11 pages, latex, no figures
Particles, Fields, and Gravitation, American Institute of Physics, 1998, 234
10.1063/1.57128
CGC-98-06
gr-qc
null
It is shown that experiments of the Einstein-Podolski-Rosen type are the natural consequence of the groupoid approach to noncommutative unification of general relativity and quantum mechanics. The geometry of this model is determined by the noncommutative algebra of complex valued, compactly supported functions (with convolution as multiplication) on the groupoid G = E x D. In the model considered in the present paper E is the total space of the frame bundle over space-time, and D is the Lorentz group. Correlations of the EPR type should be regarded as remnants of the totally non-local physics below the Planck threshold which is modelled by a noncommutative geometry.
[ { "created": "Wed, 3 Jun 1998 10:50:29 GMT", "version": "v1" } ]
2009-10-31
[ [ "Heller", "M.", "", "Vatican Observatory" ], [ "Sasin", "W.", "", "Institute of Mathematics,\n Warsaw University of Technology" ] ]
It is shown that experiments of the Einstein-Podolski-Rosen type are the natural consequence of the groupoid approach to noncommutative unification of general relativity and quantum mechanics. The geometry of this model is determined by the noncommutative algebra of complex valued, compactly supported functions (with convolution as multiplication) on the groupoid G = E x D. In the model considered in the present paper E is the total space of the frame bundle over space-time, and D is the Lorentz group. Correlations of the EPR type should be regarded as remnants of the totally non-local physics below the Planck threshold which is modelled by a noncommutative geometry.
1310.6287
Romualdo Tresguerres
Romualdo Tresguerres
Thermodynamics in dynamical spacetimes
13 Revtex pages, no figures; matches the published version
Phys. Rev. D 89, 064032 (2014)
10.1103/PhysRevD.89.064032
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We derive a general formulation of the laws of irreversible thermodynamics in the presence of electromagnetism and gravity. For the handling of macroscopic material media, we use as a guide the field equations and the Noether identities of fundamental matter as deduced in the framework of gauge theories of the Poincar\'e$\otimes U(1)$ group.
[ { "created": "Wed, 23 Oct 2013 16:41:54 GMT", "version": "v1" }, { "created": "Tue, 5 Nov 2013 22:55:36 GMT", "version": "v2" }, { "created": "Thu, 20 Mar 2014 14:45:44 GMT", "version": "v3" } ]
2014-03-26
[ [ "Tresguerres", "Romualdo", "" ] ]
We derive a general formulation of the laws of irreversible thermodynamics in the presence of electromagnetism and gravity. For the handling of macroscopic material media, we use as a guide the field equations and the Noether identities of fundamental matter as deduced in the framework of gauge theories of the Poincar\'e$\otimes U(1)$ group.
gr-qc/0104090
Jose M. M. Senovilla
G. Bergqvist and J.M.M. Senovilla
Null cone preserving maps, causal tensors and algebraic Rainich theory
36 pages, no figures, LaTeX file
Class.Quant.Grav. 18 (2001) 5299-5326
10.1088/0264-9381/18/23/323
null
gr-qc math-ph math.DG math.MP
null
A rank-n tensor on a Lorentzian manifold V whose contraction with n arbitrary causal future directed vectors is non-negative is said to have the dominant property. These tensors, up to sign, are called causal tensors, and we determine their general properties in dimension N. We prove that rank-2 tensors which map the null cone on itself are causal. It is known that, to any tensor A on V there is a corresponding ``superenergy'' (s-e) tensor T{A} which always has the dominant property. We prove that, conversely, any symmetric rank-2 tensor with the dominant property can be written in a canonical way as a sum of N s-e tensors of simple forms. We show that the square of any rank-2 s-e tensor is proportional to the metric if N<5, and that this holds for the s-e tensor of any simple form for arbitrary N. Conversely, we prove that any symmetric rank-2 tensor T whose square is proportional to the metric must be, up to sign, the s-e of a simple p-form, and that the trace of T determines the rank p of the form. This generalises, both with respect to N and the rank p, the classical algebraic Rainich conditions, which are necessary and sufficient conditions for a metric to originate in some physical field, and has a geometric interpretation: the set of s-e tensors of simple forms is precisely the set of tensors which preserve the null cone and its time orientation. It also means that all involutory Lorentz transformations (LT) can be represented as s-e tensors of simple forms, and that any rank-2 s-e tensor is the sum of at most N conformally involutory LT. Non-symmetric null cone preserving maps are shown to have a causal symmetric part and are classified according to the null eigenvectors of the skew-symmetric part. We thus obtain a complete classification of all conformal LT and singular null cone preserving maps on V.
[ { "created": "Thu, 26 Apr 2001 15:46:23 GMT", "version": "v1" } ]
2009-11-07
[ [ "Bergqvist", "G.", "" ], [ "Senovilla", "J. M. M.", "" ] ]
A rank-n tensor on a Lorentzian manifold V whose contraction with n arbitrary causal future directed vectors is non-negative is said to have the dominant property. These tensors, up to sign, are called causal tensors, and we determine their general properties in dimension N. We prove that rank-2 tensors which map the null cone on itself are causal. It is known that, to any tensor A on V there is a corresponding ``superenergy'' (s-e) tensor T{A} which always has the dominant property. We prove that, conversely, any symmetric rank-2 tensor with the dominant property can be written in a canonical way as a sum of N s-e tensors of simple forms. We show that the square of any rank-2 s-e tensor is proportional to the metric if N<5, and that this holds for the s-e tensor of any simple form for arbitrary N. Conversely, we prove that any symmetric rank-2 tensor T whose square is proportional to the metric must be, up to sign, the s-e of a simple p-form, and that the trace of T determines the rank p of the form. This generalises, both with respect to N and the rank p, the classical algebraic Rainich conditions, which are necessary and sufficient conditions for a metric to originate in some physical field, and has a geometric interpretation: the set of s-e tensors of simple forms is precisely the set of tensors which preserve the null cone and its time orientation. It also means that all involutory Lorentz transformations (LT) can be represented as s-e tensors of simple forms, and that any rank-2 s-e tensor is the sum of at most N conformally involutory LT. Non-symmetric null cone preserving maps are shown to have a causal symmetric part and are classified according to the null eigenvectors of the skew-symmetric part. We thus obtain a complete classification of all conformal LT and singular null cone preserving maps on V.
1106.5743
Sarbari Guha
Sarbari Guha and Subenoy Chakraborty
Five-dimensional warped product space-time with time-dependent warp factor and cosmology of the four-dimensional universe
11 pages, no figures, accepted for publication in International Journal of Theoretical Physics
null
10.1007/s10773-011-0877-9
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper, we have studied a 5-dimensional warped product space-time with a time-dependent warp factor. This warp factor plays an important role in localizing matter to the 4-dimensional hypersurface constituting the observed universe and leads to a geometric interpretation of dynamical dark energy. The five-dimensional field equations are constructed and its solutions are obtained. The nature of modifications produced by this warp factor in the bulk geometry is discussed. The hypersurface is described by a flat FRW-type metric in the ordinary spatial dimension. It is found that the effective cosmological constant of the four-dimensional universe is a variable quantity monitored by the time-dependent warp factor. The universe is initially decelerated, but subsequently makes a transition to an accelerated phase at later times.
[ { "created": "Tue, 28 Jun 2011 17:54:21 GMT", "version": "v1" } ]
2011-07-14
[ [ "Guha", "Sarbari", "" ], [ "Chakraborty", "Subenoy", "" ] ]
In this paper, we have studied a 5-dimensional warped product space-time with a time-dependent warp factor. This warp factor plays an important role in localizing matter to the 4-dimensional hypersurface constituting the observed universe and leads to a geometric interpretation of dynamical dark energy. The five-dimensional field equations are constructed and its solutions are obtained. The nature of modifications produced by this warp factor in the bulk geometry is discussed. The hypersurface is described by a flat FRW-type metric in the ordinary spatial dimension. It is found that the effective cosmological constant of the four-dimensional universe is a variable quantity monitored by the time-dependent warp factor. The universe is initially decelerated, but subsequently makes a transition to an accelerated phase at later times.
1804.06874
Pablo Le\'on
C. Las Heras, P. Leon
Using MGD gravitational decoupling to extend the isotropic solutions of Einstein equations to the anisotropical domain
18 pages, 12 figures. Some references were added
Fortsch.Phys. 66 (2018) 070036
10.1002/prop.201800036
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The aim of this work is to obtain new analitical solutions for Einstein equations in the anisotropical domain. This will be done via the minimal geometric deformation (MGD) approach, which is a simple and systematical method that allow us to decouple the Einstein equations. It requires a perfect fluid known solution that we will choose to be Finch-Skeas(FS) solution. Two different constraints were applied, and in each case we found an interval of values for the free parameters, where necesarly other physical solutions shall live.
[ { "created": "Wed, 18 Apr 2018 18:44:38 GMT", "version": "v1" }, { "created": "Wed, 2 May 2018 13:23:56 GMT", "version": "v2" }, { "created": "Wed, 16 May 2018 01:23:49 GMT", "version": "v3" } ]
2018-08-21
[ [ "Heras", "C. Las", "" ], [ "Leon", "P.", "" ] ]
The aim of this work is to obtain new analitical solutions for Einstein equations in the anisotropical domain. This will be done via the minimal geometric deformation (MGD) approach, which is a simple and systematical method that allow us to decouple the Einstein equations. It requires a perfect fluid known solution that we will choose to be Finch-Skeas(FS) solution. Two different constraints were applied, and in each case we found an interval of values for the free parameters, where necesarly other physical solutions shall live.
1209.4435
Hassan Murad
Mohammad Hassan Murad
A new well behaved class of charge analogue of Adler's relativistic exact solution
Accepted by Astrophysics and Space Science
null
10.1007/s10509-012-1258-4
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The paper presents a new class of parametric interior solutions of Einstein-Maxwell field equations in general relativity for a static spherically symmetric distribution of a charged perfect fluid with a particular form of electric field intensity. This solution gives us wide range of parameter, K, for which the solution is well behaved hence, suitable for modeling of superdense star. For this solution the gravitational mass of a superdense object is maximized with all degree of suitability by assuming the surface density of the star equal to the normal nuclear density 2.5E17 kg/m3. By this model we obtain the mass of the Crab pulsar 1.401 Solar mass and the radius 12.98 km constraining the moment of inertia parameter greater than 1.61 for the conservative estimate of Crab nebula mass 2 Solar mass and 2.0156 Solar mass with radius 14.07 km constraining the moment of inertia parameter greater than 3.04 for the newest estimate of Crab nebula mass 4.6 Solar mass which are quite well in agreement with the possible values of mass and radius of Crab pulsar.Besides this, our model yields the moments of inertia for PSR J0737-3039A and PSR J0737-3039B are 1.4624E38 kgm2 and 1.2689E38 kgm2 respectively. It has been observed that under well behaved conditions this class of parametric solution gives us the maximum gravitational mass of causal superdense object 2.8020 Solar mass with radius 14.49 km, surface redshift 0.4319, charge 4.67E20 C, and central density 2.68 times nuclear density.
[ { "created": "Thu, 20 Sep 2012 06:42:58 GMT", "version": "v1" }, { "created": "Sat, 22 Sep 2012 08:23:27 GMT", "version": "v2" } ]
2012-09-25
[ [ "Murad", "Mohammad Hassan", "" ] ]
The paper presents a new class of parametric interior solutions of Einstein-Maxwell field equations in general relativity for a static spherically symmetric distribution of a charged perfect fluid with a particular form of electric field intensity. This solution gives us wide range of parameter, K, for which the solution is well behaved hence, suitable for modeling of superdense star. For this solution the gravitational mass of a superdense object is maximized with all degree of suitability by assuming the surface density of the star equal to the normal nuclear density 2.5E17 kg/m3. By this model we obtain the mass of the Crab pulsar 1.401 Solar mass and the radius 12.98 km constraining the moment of inertia parameter greater than 1.61 for the conservative estimate of Crab nebula mass 2 Solar mass and 2.0156 Solar mass with radius 14.07 km constraining the moment of inertia parameter greater than 3.04 for the newest estimate of Crab nebula mass 4.6 Solar mass which are quite well in agreement with the possible values of mass and radius of Crab pulsar.Besides this, our model yields the moments of inertia for PSR J0737-3039A and PSR J0737-3039B are 1.4624E38 kgm2 and 1.2689E38 kgm2 respectively. It has been observed that under well behaved conditions this class of parametric solution gives us the maximum gravitational mass of causal superdense object 2.8020 Solar mass with radius 14.49 km, surface redshift 0.4319, charge 4.67E20 C, and central density 2.68 times nuclear density.
2407.12314
Abdallah Al Zahrani M.
A. M. Al Zahrani, A. Al-Jama
Charged Particles Capture Cross-Section by a Weakly Charged Schwarzschild Black Hole
Accepted for publication in Research in Astronomy and Astrophysics journal
null
10.1088/1674-4527/ad63e6
null
gr-qc astro-ph.HE
http://creativecommons.org/licenses/by/4.0/
We study the capture cross-section of charged particles by a weakly charged Schwarzschild black hole. The dependence of the maximum impact parameter for capture on the particle's energy is investigated numerically for different values of the electromagnetic coupling strength between the particle and the black hole. The capture cross-section is then calculated. We show that the capture cross-section is independent of the electromagnetic coupling for ultra-relativistic particles. The astrophysical implications of our results are discussed.
[ { "created": "Wed, 17 Jul 2024 04:46:52 GMT", "version": "v1" } ]
2024-07-18
[ [ "Zahrani", "A. M. Al", "" ], [ "Al-Jama", "A.", "" ] ]
We study the capture cross-section of charged particles by a weakly charged Schwarzschild black hole. The dependence of the maximum impact parameter for capture on the particle's energy is investigated numerically for different values of the electromagnetic coupling strength between the particle and the black hole. The capture cross-section is then calculated. We show that the capture cross-section is independent of the electromagnetic coupling for ultra-relativistic particles. The astrophysical implications of our results are discussed.
1910.05286
Carlos A. R. Herdeiro
Yves Brihaye, Carlos Herdeiro and Eugen Radu
Black hole spontaneous scalarisation with a positive cosmological constant
15 pages, 4 figures
null
10.1016/j.physletb.2020.135269
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
A scalar field non-minimally coupled to certain geometric [or matter] invariants which are sourced by [electro]vacuum black holes (BHs) may spontaneously grow around the latter, due to a tachyonic instability. This process is expected to lead to a new, dynamically preferred, equilibrium state: a scalarised BH. The most studied geometric [matter] source term for such spontaneous BH scalarisation is the Gauss-Bonnet quadratic curvature [Maxwell invariant]. This phenomenon has been mostly analysed for asymptotically flat spacetimes. Here we consider the impact of a positive cosmological constant, which introduces a cosmological horizon. The cosmological constant does not change the local conditions on the scalar coupling for a tachyonic instability of the scalar-free BHs to emerge. But it leaves a significant imprint on the possible new scalarised BHs. It is shown that no scalarised BH solutions exist, under a smoothness assumption, if the scalar field is confined between the BH and cosmological horizons. Admitting the scalar field can extend beyond the cosmological horizon, we construct new scalarised BHs. These are asymptotically de Sitter in the (matter) Einstein-Maxwell-scalar model, with only mild difference with respect to their asymptotically flat counterparts. But in the (geometric) extended-scalar-tensor-Gauss-Bonnet-scalar model, they have necessarily non-standard asymptotics, as the tachyonic instability dominates in the far field. This interpretation is supported by the analysis of a test tachyon on a de Sitter background.
[ { "created": "Fri, 11 Oct 2019 16:27:19 GMT", "version": "v1" } ]
2020-02-19
[ [ "Brihaye", "Yves", "" ], [ "Herdeiro", "Carlos", "" ], [ "Radu", "Eugen", "" ] ]
A scalar field non-minimally coupled to certain geometric [or matter] invariants which are sourced by [electro]vacuum black holes (BHs) may spontaneously grow around the latter, due to a tachyonic instability. This process is expected to lead to a new, dynamically preferred, equilibrium state: a scalarised BH. The most studied geometric [matter] source term for such spontaneous BH scalarisation is the Gauss-Bonnet quadratic curvature [Maxwell invariant]. This phenomenon has been mostly analysed for asymptotically flat spacetimes. Here we consider the impact of a positive cosmological constant, which introduces a cosmological horizon. The cosmological constant does not change the local conditions on the scalar coupling for a tachyonic instability of the scalar-free BHs to emerge. But it leaves a significant imprint on the possible new scalarised BHs. It is shown that no scalarised BH solutions exist, under a smoothness assumption, if the scalar field is confined between the BH and cosmological horizons. Admitting the scalar field can extend beyond the cosmological horizon, we construct new scalarised BHs. These are asymptotically de Sitter in the (matter) Einstein-Maxwell-scalar model, with only mild difference with respect to their asymptotically flat counterparts. But in the (geometric) extended-scalar-tensor-Gauss-Bonnet-scalar model, they have necessarily non-standard asymptotics, as the tachyonic instability dominates in the far field. This interpretation is supported by the analysis of a test tachyon on a de Sitter background.
2205.00594
Ran Li
Ran Li, Jin Wang
Non-Markovian dynamics of black hole phase transition
arXiv admin note: text overlap with arXiv:2201.06138
null
10.1103/PhysRevD.106.104039
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We provide a comprehensive study on the non-Markovian dynamics of the black hole phase transitions based on the underlying free energy landscape. By assuming that the transition processes between different black hole states are stochastic, the non-Markovian dynamics of the black hole phase transition is governed by the generalized Langevin equation with the time-dependent friction that represents the memory effect from the effective thermal bath when the timescale of the system is comparable or shorter than the timescale of the effective thermal bath. We consider the first passage problem associated with the black hole phase transitions and derive the analytical expressions of the mean first passage time in the weak, intermediate, and large friction regimes. As the concrete examples, we study the effects of three types of time dependent friction kernel (delta function friction, exponentially decayed friction, and oscillatory friction) on the dynamics of Hawking-Page phase transition and the small/large RNAdS black hole phase transition. we found that there is a kinetic turnover point for each type of friction kernel when the friction strength varies. For the exponentially decayed friction kernel, it is shown that the non-Markovian effect slows down the phase transition dynamics in the weak friction regime and speeds up the transition process in the strong friction regime. For the oscillating decayed friction kernel, we found kinetic resonances when the oscillating frequency of the effective thermal bath is equal to the oscillating frequency of the black hole state in the initial potential well on the free energy landscape.
[ { "created": "Mon, 2 May 2022 00:44:44 GMT", "version": "v1" } ]
2022-11-30
[ [ "Li", "Ran", "" ], [ "Wang", "Jin", "" ] ]
We provide a comprehensive study on the non-Markovian dynamics of the black hole phase transitions based on the underlying free energy landscape. By assuming that the transition processes between different black hole states are stochastic, the non-Markovian dynamics of the black hole phase transition is governed by the generalized Langevin equation with the time-dependent friction that represents the memory effect from the effective thermal bath when the timescale of the system is comparable or shorter than the timescale of the effective thermal bath. We consider the first passage problem associated with the black hole phase transitions and derive the analytical expressions of the mean first passage time in the weak, intermediate, and large friction regimes. As the concrete examples, we study the effects of three types of time dependent friction kernel (delta function friction, exponentially decayed friction, and oscillatory friction) on the dynamics of Hawking-Page phase transition and the small/large RNAdS black hole phase transition. we found that there is a kinetic turnover point for each type of friction kernel when the friction strength varies. For the exponentially decayed friction kernel, it is shown that the non-Markovian effect slows down the phase transition dynamics in the weak friction regime and speeds up the transition process in the strong friction regime. For the oscillating decayed friction kernel, we found kinetic resonances when the oscillating frequency of the effective thermal bath is equal to the oscillating frequency of the black hole state in the initial potential well on the free energy landscape.
2309.11491
Shammi Tahura
Shammi Tahura, Hassan Khalvati, Huan Yang
Vacuum Spacetime With Multipole Moments: The Minimal Size Conjecture, Black Hole Shadow, and Gravitational Wave Observables
18 pages; 8 figures; v2: Section 3B modified, derivation of minimal size corrected, results remain the same; v3: Matches published version
null
10.1103/PhysRevD.109.124025
null
gr-qc astro-ph.HE
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this work, we explicitly construct the vacuum solution of Einstein's equations with prescribed multipole moments. By observing the behavior of the multipole spacetime metric at small distances, we conjecture that for a sufficiently large multipole moment, there is a minimal size below which no object in nature can support such a moment. The examples we have investigated suggest that such minimal size scales as $(M_n)^{1/(n+1)}$ (instead of $(M_n/M)^{1/n}$), where $M$ is the mass and $M_n$ is the $n$th order multipole moment. With the metric of the "multipole spacetime", we analyze the shape of black hole shadow for various multipole moments and discuss the prospects of constraining the moments from shadow observations. In addition, we discuss the shift of gravitational wave phase with respect to those of the Kerr spacetime, for a test particle moving around an object with this set of multipole moments. These phase shifts are required for the program of mapping out the spacetime multipole moments based on gravitational wave observations of extreme mass-ratio inspirals.
[ { "created": "Wed, 20 Sep 2023 17:39:35 GMT", "version": "v1" }, { "created": "Wed, 8 May 2024 22:58:32 GMT", "version": "v2" }, { "created": "Fri, 21 Jun 2024 01:57:42 GMT", "version": "v3" } ]
2024-06-24
[ [ "Tahura", "Shammi", "" ], [ "Khalvati", "Hassan", "" ], [ "Yang", "Huan", "" ] ]
In this work, we explicitly construct the vacuum solution of Einstein's equations with prescribed multipole moments. By observing the behavior of the multipole spacetime metric at small distances, we conjecture that for a sufficiently large multipole moment, there is a minimal size below which no object in nature can support such a moment. The examples we have investigated suggest that such minimal size scales as $(M_n)^{1/(n+1)}$ (instead of $(M_n/M)^{1/n}$), where $M$ is the mass and $M_n$ is the $n$th order multipole moment. With the metric of the "multipole spacetime", we analyze the shape of black hole shadow for various multipole moments and discuss the prospects of constraining the moments from shadow observations. In addition, we discuss the shift of gravitational wave phase with respect to those of the Kerr spacetime, for a test particle moving around an object with this set of multipole moments. These phase shifts are required for the program of mapping out the spacetime multipole moments based on gravitational wave observations of extreme mass-ratio inspirals.
gr-qc/0310031
Irina Dymnikova
Irina Dymnikova
$\Lambda^{mu}_{\nu}$ geometries from the point of view of different observers
7 pages, 11 figures, Talk at the Fourth International Conference on Physics Beyond the Standard Model "Beyond the Desert'03", Germany, 2003
null
null
null
gr-qc
null
$\Lambda^{\mu}_{\nu}$-geometry is a geometry with a variable cosmological term described by a second-rank symmetric tensor $\Lambda^{\mu}_{\nu}$ whose asymptotics are Einstein cosmological term $\Lambda \delta ^{\mu}_{\nu}$ at the origin and $\lambda \delta ^{\mu}_{\nu}$ at infinity (with $\lambda < \Lambda$). It corresponds to extension of the algebraic structure of the Einstein cosmological term $\Lambda \delta ^{\mu}_{\nu}$ in such a way that a scalar $\Lambda$ describing vacuum energy density as $\rho_{vac}=8\pi G \Lambda$ (with $\rho_{vac}$=const by virtue of the Bianchi identities), becomes explicite related to the appropriate component, $\Lambda^0_0$, of an appropriate stress-energy tensor, $T^{\mu}_{\nu}=8\pi G\Lambda^{\mu}_{\nu}$ whose vacuum properties follow from its symmetry, $T_0^0=T_1^1$, and whose variability follows from the contracted Bianchi identities. In the spherically symmetric case existence of such geometries in frame of GR follows from imposing on Einstein equations requirements of finiteness of the ADM mass $m$, and of regularity of density and pressures. Dependently on parameters $m$ and $q=\sqrt{\Lambda /\lambda}$, $\Lambda^{\mu}_{\nu}$ geometry describes five types of configurations. We summarize here the results which tell us how these configurations look from the point of view of different observers: a static observer, a Lemaitre co-moving observer, and a Kantowski-Sachs observer.
[ { "created": "Mon, 6 Oct 2003 10:02:22 GMT", "version": "v1" } ]
2016-08-31
[ [ "Dymnikova", "Irina", "" ] ]
$\Lambda^{\mu}_{\nu}$-geometry is a geometry with a variable cosmological term described by a second-rank symmetric tensor $\Lambda^{\mu}_{\nu}$ whose asymptotics are Einstein cosmological term $\Lambda \delta ^{\mu}_{\nu}$ at the origin and $\lambda \delta ^{\mu}_{\nu}$ at infinity (with $\lambda < \Lambda$). It corresponds to extension of the algebraic structure of the Einstein cosmological term $\Lambda \delta ^{\mu}_{\nu}$ in such a way that a scalar $\Lambda$ describing vacuum energy density as $\rho_{vac}=8\pi G \Lambda$ (with $\rho_{vac}$=const by virtue of the Bianchi identities), becomes explicite related to the appropriate component, $\Lambda^0_0$, of an appropriate stress-energy tensor, $T^{\mu}_{\nu}=8\pi G\Lambda^{\mu}_{\nu}$ whose vacuum properties follow from its symmetry, $T_0^0=T_1^1$, and whose variability follows from the contracted Bianchi identities. In the spherically symmetric case existence of such geometries in frame of GR follows from imposing on Einstein equations requirements of finiteness of the ADM mass $m$, and of regularity of density and pressures. Dependently on parameters $m$ and $q=\sqrt{\Lambda /\lambda}$, $\Lambda^{\mu}_{\nu}$ geometry describes five types of configurations. We summarize here the results which tell us how these configurations look from the point of view of different observers: a static observer, a Lemaitre co-moving observer, and a Kantowski-Sachs observer.
0705.2519
Alessandro Nagar
Thibault Damour, Alessandro Nagar
Faithful Effective-One-Body waveforms of small-mass-ratio coalescing black-hole binaries
13 pages, 6 figures. To appear in Phys. Rev. D
Phys.Rev.D76:064028,2007
10.1103/PhysRevD.76.064028
null
gr-qc
null
We address the problem of constructing high-accuracy, faithful analytic waveforms describing the gravitational wave signal emitted by inspiralling and coalescing binary black holes. We work within the Effective-One-Body (EOB) framework and propose a methodology for improving the current (waveform)implementations of this framework based on understanding, element by element, the physics behind each feature of the waveform, and on systematically comparing various EOB-based waveforms with ``exact'' waveforms obtained by numerical relativity approaches. The present paper focuses on small-mass-ratio non-spinning binary systems, which can be conveniently studied by Regge-Wheeler-Zerilli-type methods. Our results include: (i) a resummed, 3PN-accurate description of the inspiral waveform, (ii) a better description of radiation reaction during the plunge, (iii) a refined analytic expression for the plunge waveform, (iv) an improved treatment of the matching between the plunge and ring-down waveforms. This improved implementation of the EOB approach allows us to construct complete analytic waveforms which exhibit a remarkable agreement with the ``exact'' ones in modulus, frequency and phase. In particular, the analytic and numerical waveforms stay in phase, during the whole process, within $\pm 1.1 %$ of a cycle. We expect that the extension of our methodology to the comparable-mass case will be able to generate comparably accurate analytic waveforms of direct use for the ground-based network of interferometric detectors of gravitational waves.
[ { "created": "Thu, 17 May 2007 11:47:54 GMT", "version": "v1" }, { "created": "Thu, 26 Jul 2007 15:33:55 GMT", "version": "v2" } ]
2008-11-26
[ [ "Damour", "Thibault", "" ], [ "Nagar", "Alessandro", "" ] ]
We address the problem of constructing high-accuracy, faithful analytic waveforms describing the gravitational wave signal emitted by inspiralling and coalescing binary black holes. We work within the Effective-One-Body (EOB) framework and propose a methodology for improving the current (waveform)implementations of this framework based on understanding, element by element, the physics behind each feature of the waveform, and on systematically comparing various EOB-based waveforms with ``exact'' waveforms obtained by numerical relativity approaches. The present paper focuses on small-mass-ratio non-spinning binary systems, which can be conveniently studied by Regge-Wheeler-Zerilli-type methods. Our results include: (i) a resummed, 3PN-accurate description of the inspiral waveform, (ii) a better description of radiation reaction during the plunge, (iii) a refined analytic expression for the plunge waveform, (iv) an improved treatment of the matching between the plunge and ring-down waveforms. This improved implementation of the EOB approach allows us to construct complete analytic waveforms which exhibit a remarkable agreement with the ``exact'' ones in modulus, frequency and phase. In particular, the analytic and numerical waveforms stay in phase, during the whole process, within $\pm 1.1 %$ of a cycle. We expect that the extension of our methodology to the comparable-mass case will be able to generate comparably accurate analytic waveforms of direct use for the ground-based network of interferometric detectors of gravitational waves.
gr-qc/0401064
Bijaya Kumar Sahoo
B.K.Sahoo and L.P.Singh
Gravitational Waves in Generalised Brans-Dicke Theory
7Pages,no figures
Mod.Phys.Lett. A19 (2004) 1745-1758
10.1142/S0217732304014021
null
gr-qc
null
We have solved cosmological gravitational Wave(GW)equation in the frame work of Generalised Brans-Dicke(GBD) theory for all epochs of the Universe.The solutions are expressed in terms of the present value of the Brans-Dicke coupling parameter $\omega(\phi)$.It is seen that the solutions represent travelling growing modes for negative values of $\omega_{0}$ for all epochs of the Universe.
[ { "created": "Thu, 15 Jan 2004 09:09:28 GMT", "version": "v1" } ]
2009-11-10
[ [ "Sahoo", "B. K.", "" ], [ "Singh", "L. P.", "" ] ]
We have solved cosmological gravitational Wave(GW)equation in the frame work of Generalised Brans-Dicke(GBD) theory for all epochs of the Universe.The solutions are expressed in terms of the present value of the Brans-Dicke coupling parameter $\omega(\phi)$.It is seen that the solutions represent travelling growing modes for negative values of $\omega_{0}$ for all epochs of the Universe.
1503.08073
Allan Alinea
Allan L. Alinea, Takahiro Kubota, Yukari Nakanishi, Wade Naylor (Osaka U.)
Adiabatic regularisation of power spectra in $k$-inflation
17 pages; v2, typos corrected & reference added; v3, rewrote some parts for clarity
JCAP 06 (2015) 019
10.1088/1475-7516/2015/06/019
OU-HET 853
gr-qc astro-ph.CO hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We look at the question posed by Parker et al. about the effect of UV regularisation on the power spectrum for inflation. Focusing on the slow-roll $k$-inflation, we show that up to second order in the Hubble and sound flow parameters, the adiabatic regularisation of such model leads to no difference in the power spectrum apart from certain cases that violate near scale invariant power spectra. Furthermore, extending to non-minimal $k$-inflation, we establish the equivalence of the subtraction terms in the adiabatic regularisation of the power spectrum in Jordan and Einstein frames.
[ { "created": "Thu, 26 Mar 2015 03:32:33 GMT", "version": "v1" }, { "created": "Mon, 6 Apr 2015 20:41:29 GMT", "version": "v2" }, { "created": "Sun, 5 Jul 2015 01:44:52 GMT", "version": "v3" } ]
2015-07-07
[ [ "Alinea", "Allan L.", "", "Osaka\n U." ], [ "Kubota", "Takahiro", "", "Osaka\n U." ], [ "Nakanishi", "Yukari", "", "Osaka\n U." ], [ "Naylor", "Wade", "", "Osaka\n U." ] ]
We look at the question posed by Parker et al. about the effect of UV regularisation on the power spectrum for inflation. Focusing on the slow-roll $k$-inflation, we show that up to second order in the Hubble and sound flow parameters, the adiabatic regularisation of such model leads to no difference in the power spectrum apart from certain cases that violate near scale invariant power spectra. Furthermore, extending to non-minimal $k$-inflation, we establish the equivalence of the subtraction terms in the adiabatic regularisation of the power spectrum in Jordan and Einstein frames.
2310.16007
Sebasti\'an Bahamonde Dr
Katsuki Aoki, Sebastian Bahamonde, Jorge Gigante Valcarcel, Mohammad Ali Gorji
Cosmological Perturbation Theory in Metric-Affine Gravity
Matches published version in PRD. 23+20 pages, 5 appendices
Phys.Rev.D 110 (2024) 2, 024017
10.1103/PhysRevD.110.024017
null
gr-qc astro-ph.CO hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We formulate cosmological perturbation theory around the spatially curved FLRW background in the context of metric-affine gauge theory of gravity which includes torsion and nonmetricity. Performing scalar-vector-tensor decomposition of the spatial perturbations, we find that the theory displays a rich perturbation spectrum with helicities 0, 1, 2 and 3, on top of the usual scalar, vector and tensor metric perturbations arising from Riemannian geometry. Accordingly, the theory provides a diverse phenomenology, e.g. the helicity-2 modes of the torsion and/or nonmetricity tensors source helicity-2 metric tensor perturbation at the linear level leading to the production of gravitational waves. As an immediate application, we study linear perturbation of the nonmetricity helicity-3 modes for a general parity-preserving action of metric-affine gravity which includes quadratic terms in curvature, torsion, and nonmetricity. We then find the conditions to avoid possible instabilities in the helicity-3 modes of the spin-3 field.
[ { "created": "Tue, 24 Oct 2023 17:02:03 GMT", "version": "v1" }, { "created": "Wed, 17 Jul 2024 01:21:04 GMT", "version": "v2" } ]
2024-07-18
[ [ "Aoki", "Katsuki", "" ], [ "Bahamonde", "Sebastian", "" ], [ "Valcarcel", "Jorge Gigante", "" ], [ "Gorji", "Mohammad Ali", "" ] ]
We formulate cosmological perturbation theory around the spatially curved FLRW background in the context of metric-affine gauge theory of gravity which includes torsion and nonmetricity. Performing scalar-vector-tensor decomposition of the spatial perturbations, we find that the theory displays a rich perturbation spectrum with helicities 0, 1, 2 and 3, on top of the usual scalar, vector and tensor metric perturbations arising from Riemannian geometry. Accordingly, the theory provides a diverse phenomenology, e.g. the helicity-2 modes of the torsion and/or nonmetricity tensors source helicity-2 metric tensor perturbation at the linear level leading to the production of gravitational waves. As an immediate application, we study linear perturbation of the nonmetricity helicity-3 modes for a general parity-preserving action of metric-affine gravity which includes quadratic terms in curvature, torsion, and nonmetricity. We then find the conditions to avoid possible instabilities in the helicity-3 modes of the spin-3 field.
gr-qc/0409091
Yuan-Zhong Zhang
A. Bhadra and K.K. Nandi
omega dependence of the scalar field in Brans-Dicke theory
6 pages
Phys.Rev. D64 (2001) 087501
10.1103/PhysRevD.64.087501
null
gr-qc
null
This article examines the claim that the Brans-Dicke scalar field \phi \to \phi_{0} + O(1/\sqrt{\omega}) for large $\omega$ when the matter field is traceless. It is argued that such a claim can not be true in general.
[ { "created": "Fri, 24 Sep 2004 08:03:50 GMT", "version": "v1" } ]
2009-11-10
[ [ "Bhadra", "A.", "" ], [ "Nandi", "K. K.", "" ] ]
This article examines the claim that the Brans-Dicke scalar field \phi \to \phi_{0} + O(1/\sqrt{\omega}) for large $\omega$ when the matter field is traceless. It is argued that such a claim can not be true in general.
1111.0400
James D. E. Grant
Piotr T. Chru\'sciel and James D. E. Grant
On Lorentzian causality with continuous metrics
Minor changes. Version to appear in Classical and Quantum Gravity
null
10.1088/0264-9381/29/14/145001
Preprint UWThPh-2011-33
gr-qc math-ph math.DG math.MP
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We present a systematic study of causality theory on Lorentzian manifolds with continuous metrics. Examples are given which show that some standard facts in smooth Lorentzian geometry, such as light-cones being hypersurfaces, are wrong when metrics which are merely continuous are considered. We show that existence of time functions remains true on domains of dependence with continuous metrics, and that $C^{0,1}$ differentiability of the metric suffices for many key results of the smooth causality theory.
[ { "created": "Wed, 2 Nov 2011 06:12:48 GMT", "version": "v1" }, { "created": "Tue, 29 Nov 2011 19:15:31 GMT", "version": "v2" }, { "created": "Sun, 27 May 2012 17:48:52 GMT", "version": "v3" } ]
2015-06-03
[ [ "Chruściel", "Piotr T.", "" ], [ "Grant", "James D. E.", "" ] ]
We present a systematic study of causality theory on Lorentzian manifolds with continuous metrics. Examples are given which show that some standard facts in smooth Lorentzian geometry, such as light-cones being hypersurfaces, are wrong when metrics which are merely continuous are considered. We show that existence of time functions remains true on domains of dependence with continuous metrics, and that $C^{0,1}$ differentiability of the metric suffices for many key results of the smooth causality theory.
1111.1448
Micha{\l} Eckstein
Piotr T. Chru\'sciel, Micha{\l} Eckstein, Luc Nguyen, Sebastian J. Szybka
Existence of singularities in two-Kerr black holes
minor rewordings, a reference added, version identical to the one published in CQG
Class. Quantum Grav. 28 (2011) 245017
10.1088/0264-9381/28/24/245017
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We show that the angular momentum - area inequality 8\pi |J| =< A for weakly stable minimal surfaces would apply to (I^+)-regular many-Kerr solutions, if any existed. Hence we remove the undesirable hypothesis in the Hennig-Neugebauer proof of non-existence of well behaved two-component solutions.
[ { "created": "Sun, 6 Nov 2011 20:15:04 GMT", "version": "v1" }, { "created": "Sat, 3 Dec 2011 10:37:16 GMT", "version": "v2" } ]
2011-12-06
[ [ "Chruściel", "Piotr T.", "" ], [ "Eckstein", "Michał", "" ], [ "Nguyen", "Luc", "" ], [ "Szybka", "Sebastian J.", "" ] ]
We show that the angular momentum - area inequality 8\pi |J| =< A for weakly stable minimal surfaces would apply to (I^+)-regular many-Kerr solutions, if any existed. Hence we remove the undesirable hypothesis in the Hennig-Neugebauer proof of non-existence of well behaved two-component solutions.
2306.12895
Alexey Golovnev
Alexey Golovnev
A Pamphlet against The Energy
6 pages, 4 pictures, 1 epigraph
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
It is a well-known fact that there is no well-defined notion of conserved energy in gravity. In my opinion, it is not a big deal. As a conserved quantity, energy is a rather artificial invention which works perfectly well as long as we have a natural symmetry with respect to translations in time, however not when there ceases to be any notion of an objective time, rather than a mere coordinate. However, recently we have got an essential progress in teleparallel models of gravity, with emerging opinions of having solved the problem of energy. I explain why I think it simply makes no good sense to go for solving a non-existent problem, and the correct answer is just that in general there is no such thing as The Energy. (It has just been presented online at the Conference on Geometric Foundations of Gravity 2023 in Tartu, Estonia.)
[ { "created": "Thu, 22 Jun 2023 14:02:48 GMT", "version": "v1" } ]
2023-06-23
[ [ "Golovnev", "Alexey", "" ] ]
It is a well-known fact that there is no well-defined notion of conserved energy in gravity. In my opinion, it is not a big deal. As a conserved quantity, energy is a rather artificial invention which works perfectly well as long as we have a natural symmetry with respect to translations in time, however not when there ceases to be any notion of an objective time, rather than a mere coordinate. However, recently we have got an essential progress in teleparallel models of gravity, with emerging opinions of having solved the problem of energy. I explain why I think it simply makes no good sense to go for solving a non-existent problem, and the correct answer is just that in general there is no such thing as The Energy. (It has just been presented online at the Conference on Geometric Foundations of Gravity 2023 in Tartu, Estonia.)
gr-qc/0510080
Romualdo Tresguerres
A. Tiemblo and R. Tresguerres
Towards a general solution of the Hamiltonian constraints of General Relativity
10 Revtex pages, no figures. Modified version
Gen.Rel.Grav. 38 (2006) 1839-1859
10.1007/s10714-006-0361-7
null
gr-qc
null
The present work has a double aim. On the one hand we call attention on the relationship existing between the Ashtekar formalism and other gauge-theoretical approaches to gravity, in particular the Poincar\'e Gauge Theory. On the other hand we study two kinds of solutions for the constraints of General Relativity, consisting of two mutually independent parts, namely a general three-metric-dependent contribution to the extrinsic curvature $K_{ab}$ in terms of the Cotton-York tensor, and besides it further metric independent contributions, which we analyze in particular in the presence of isotropic three-metrics.
[ { "created": "Mon, 17 Oct 2005 11:24:12 GMT", "version": "v1" }, { "created": "Wed, 5 Jul 2006 14:00:33 GMT", "version": "v2" } ]
2009-11-11
[ [ "Tiemblo", "A.", "" ], [ "Tresguerres", "R.", "" ] ]
The present work has a double aim. On the one hand we call attention on the relationship existing between the Ashtekar formalism and other gauge-theoretical approaches to gravity, in particular the Poincar\'e Gauge Theory. On the other hand we study two kinds of solutions for the constraints of General Relativity, consisting of two mutually independent parts, namely a general three-metric-dependent contribution to the extrinsic curvature $K_{ab}$ in terms of the Cotton-York tensor, and besides it further metric independent contributions, which we analyze in particular in the presence of isotropic three-metrics.
2404.09107
Jose Edgar Madriz Aguilar Dr.
Jos\'e Edgar Madriz Aguilar, Diego Allan Reyna
Power law coupling Higgs-Palatini inflation with a congruence between physical and geometrical symmetries
12 pages, 3 figures
null
null
null
gr-qc hep-th math-ph math.MP
http://creativecommons.org/licenses/by/4.0/
In this paper we investigate a power law coupling Higgs inflationary model in which the background geometry is determined by the Palatini's variational principle. The geometrical symmetries of the background geometry determine the invariant form of the action of the model and the background geometry resulted is of the Weyl-integrable type. The invariant action results also invariant under the $U(1)$ group, which in general is not compatible with the Weyl group of invariance of the background geometry. However, we found compatibility conditions between the geometrical and physical symmetries of the action in the strong coupling limit. We found that if we start with a non-minimally coupled to gravity action, when we impose the congruence between the both groups of symmetries we end with an invariant action of the scalar-tensor type. We obtain a nearly scale invariant power spectrum for the inflaton fluctuations for certain values of some parameters of the model. Also we obtain va\-lues for the tensor to scalar ratio in agreement with PLANCK and BICEP observational data: $r<0.032$.
[ { "created": "Sun, 14 Apr 2024 00:20:50 GMT", "version": "v1" } ]
2024-04-16
[ [ "Aguilar", "José Edgar Madriz", "" ], [ "Reyna", "Diego Allan", "" ] ]
In this paper we investigate a power law coupling Higgs inflationary model in which the background geometry is determined by the Palatini's variational principle. The geometrical symmetries of the background geometry determine the invariant form of the action of the model and the background geometry resulted is of the Weyl-integrable type. The invariant action results also invariant under the $U(1)$ group, which in general is not compatible with the Weyl group of invariance of the background geometry. However, we found compatibility conditions between the geometrical and physical symmetries of the action in the strong coupling limit. We found that if we start with a non-minimally coupled to gravity action, when we impose the congruence between the both groups of symmetries we end with an invariant action of the scalar-tensor type. We obtain a nearly scale invariant power spectrum for the inflaton fluctuations for certain values of some parameters of the model. Also we obtain va\-lues for the tensor to scalar ratio in agreement with PLANCK and BICEP observational data: $r<0.032$.
gr-qc/9710066
Carsten Gundlach
Carsten Gundlach (Albert Einstein Institut, Potsdam)
Nonspherical perturbations of critical collapse and cosmic censorship
5 pages, RevTex, 1 figure. Changes in discussion, accepted for publication in PRD Rapid Comm
Phys.Rev.D57:7075-7079,1998
10.1103/PhysRevD.57.7075
null
gr-qc
null
Choptuik has demonstrated that naked singularities can arise in gravitational collapse from smooth, asymptotically flat initial data, and that such data have codimension one in spherical symmetry. Here we show, for perfect fluid matter with equation of state $p=\rho/3$, by perturbing around spherical symmetry, that such data have in fact codimension one in the full phase space, at least in a neighborhood of spherically symmetric data.
[ { "created": "Sun, 12 Oct 1997 18:47:04 GMT", "version": "v1" }, { "created": "Thu, 4 Jun 1998 09:21:50 GMT", "version": "v2" } ]
2009-12-30
[ [ "Gundlach", "Carsten", "", "Albert Einstein Institut, Potsdam" ] ]
Choptuik has demonstrated that naked singularities can arise in gravitational collapse from smooth, asymptotically flat initial data, and that such data have codimension one in spherical symmetry. Here we show, for perfect fluid matter with equation of state $p=\rho/3$, by perturbing around spherical symmetry, that such data have in fact codimension one in the full phase space, at least in a neighborhood of spherically symmetric data.
1706.07520
Koji Yamaguchi
Masahiro Hotta, Yasusada Nambu and Koji Yamaguchi
Soft-Hair-Enhanced Entanglement Beyond Page Curves in a Black-hole Evaporation Qubit Model
10pages, 3 figures
Phys. Rev. Lett. 120, 181301 (2018)
10.1103/PhysRevLett.120.181301
null
gr-qc hep-th quant-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We propose a model with multiple qubits that reproduces the thermal properties of 4-dimensional (4-dim) Schwarzschild black holes (BHs) by simultaneously taking account of the emission of Hawking particles and the zero-energy soft hair evaporation at horizon. The results verify that the entanglement entropy between a qubit and other subsystems, including emitted radiation, is much larger than the BH entropy analogue of the qubit, as opposed to the Page curve prediction. Our result suggests that early Hawking radiation is entangled with soft hair, and that late Hawking radiation can be highly entangled with the degrees of freedom of BH, avoiding the emergence of a firewall at the horizon.
[ { "created": "Thu, 22 Jun 2017 23:09:15 GMT", "version": "v1" }, { "created": "Wed, 28 Mar 2018 09:17:35 GMT", "version": "v2" }, { "created": "Thu, 29 Mar 2018 02:54:55 GMT", "version": "v3" }, { "created": "Sun, 6 May 2018 23:37:04 GMT", "version": "v4" } ]
2018-05-08
[ [ "Hotta", "Masahiro", "" ], [ "Nambu", "Yasusada", "" ], [ "Yamaguchi", "Koji", "" ] ]
We propose a model with multiple qubits that reproduces the thermal properties of 4-dimensional (4-dim) Schwarzschild black holes (BHs) by simultaneously taking account of the emission of Hawking particles and the zero-energy soft hair evaporation at horizon. The results verify that the entanglement entropy between a qubit and other subsystems, including emitted radiation, is much larger than the BH entropy analogue of the qubit, as opposed to the Page curve prediction. Our result suggests that early Hawking radiation is entangled with soft hair, and that late Hawking radiation can be highly entangled with the degrees of freedom of BH, avoiding the emergence of a firewall at the horizon.
1905.00678
Bhaskar Biswas
Bhaskar Biswas, Rana Nandi, Prasanta Char and Sukanta Bose
Role of crustal physics in the tidal deformation of a neutron star
26 pages, 10 figures
Phys. Rev. D 100, 044056 (2019)
10.1103/PhysRevD.100.044056
null
gr-qc astro-ph.HE nucl-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In the late inspiral phase, gravitational waves from binary neutron star mergers carry the imprint of the equation of state due to the tidally deformed structure of the components. If the stars contain solid crusts, then their shear modulus can affect the deformability of the star and, thereby, modify the emitted signal. Here, we investigate the effect of realistic equations of state (EOSs) of the crustal matter, with a realistic model for the shear modulus of the stellar crust in a fully general relativistic framework. This allows us to systematically study the deviations that are expected from fluid models. In particular, we use unified EOSs, both relativistic and non-relativistic, in our calculations. We find that realistic EOSs of crusts cause a small correction, of $\sim 1\%$, in the second Love number. This correction will likely be subdominant to the statistical error expected in LIGO-Virgo observations at their respective advanced design sensitivities, but rival that error in third generation detectors. For completeness, we also study the effect of crustal shear on the magnetic-type Love number and find it to be much smaller.
[ { "created": "Thu, 2 May 2019 11:48:44 GMT", "version": "v1" } ]
2019-09-02
[ [ "Biswas", "Bhaskar", "" ], [ "Nandi", "Rana", "" ], [ "Char", "Prasanta", "" ], [ "Bose", "Sukanta", "" ] ]
In the late inspiral phase, gravitational waves from binary neutron star mergers carry the imprint of the equation of state due to the tidally deformed structure of the components. If the stars contain solid crusts, then their shear modulus can affect the deformability of the star and, thereby, modify the emitted signal. Here, we investigate the effect of realistic equations of state (EOSs) of the crustal matter, with a realistic model for the shear modulus of the stellar crust in a fully general relativistic framework. This allows us to systematically study the deviations that are expected from fluid models. In particular, we use unified EOSs, both relativistic and non-relativistic, in our calculations. We find that realistic EOSs of crusts cause a small correction, of $\sim 1\%$, in the second Love number. This correction will likely be subdominant to the statistical error expected in LIGO-Virgo observations at their respective advanced design sensitivities, but rival that error in third generation detectors. For completeness, we also study the effect of crustal shear on the magnetic-type Love number and find it to be much smaller.
1310.2341
Dipongkar Talukder
Dipongkar Talukder, Sukanta Bose, Sarah Caudill, and Paul T. Baker
Improved Coincident and Coherent Detection Statistics for Searches for Gravitational Wave Ringdown Signals
null
Phys. Rev. D 88, 122002 (2013)
10.1103/PhysRevD.88.122002
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study an improved method for detecting gravitational wave (GW) signals from perturbed black holes by earth-based detectors in the quest for searching for intermediate-mass black holes (IMBHs). Such signals, called ringdowns, are damped sinusoids whose frequency and damping constant can be used to measure a black hole's mass and spin. Utilizing the output from a matched filter analysis pipeline, we present an improved statistic for the detection of a ringdown signal that is found to be coincident in multiple detectors. The statistic addresses the non-Gaussianity of the data without the use of an additional signal-based waveform consistency test. We also develop coherent network statistics to check for consistency of signal amplitudes and phases in the different detectors with their different orientations and signal arrival times. We find that the detection efficiency can be improved at least by a few tens of percent by applying these multi-detector statistics primarily because of the ineffectiveness of single-detector based discriminators of non-stationary noise, such as the chi-square test, in the case of ringdown signals studied here.
[ { "created": "Wed, 9 Oct 2013 04:38:36 GMT", "version": "v1" }, { "created": "Tue, 15 Oct 2013 03:04:13 GMT", "version": "v2" } ]
2013-12-16
[ [ "Talukder", "Dipongkar", "" ], [ "Bose", "Sukanta", "" ], [ "Caudill", "Sarah", "" ], [ "Baker", "Paul T.", "" ] ]
We study an improved method for detecting gravitational wave (GW) signals from perturbed black holes by earth-based detectors in the quest for searching for intermediate-mass black holes (IMBHs). Such signals, called ringdowns, are damped sinusoids whose frequency and damping constant can be used to measure a black hole's mass and spin. Utilizing the output from a matched filter analysis pipeline, we present an improved statistic for the detection of a ringdown signal that is found to be coincident in multiple detectors. The statistic addresses the non-Gaussianity of the data without the use of an additional signal-based waveform consistency test. We also develop coherent network statistics to check for consistency of signal amplitudes and phases in the different detectors with their different orientations and signal arrival times. We find that the detection efficiency can be improved at least by a few tens of percent by applying these multi-detector statistics primarily because of the ineffectiveness of single-detector based discriminators of non-stationary noise, such as the chi-square test, in the case of ringdown signals studied here.
2112.12992
Jaume Haro
Llibert Arest\'e Sal\'o and Jaume de Haro
Gravitational particle production of superheavy massive particles in Quintessential Inflation II: $\alpha$-attractors
8 pages, 4 figures. Comments will be welcome. arXiv admin note: substantial text overlap with arXiv:2108.10795, arXiv:2108.11144
null
null
null
gr-qc
http://creativecommons.org/publicdomain/zero/1.0/
We compute the gravitational production of conformally coupled superheavy particles during the phase transition from the end of inflation to the beginning of kination for $\alpha$-attractors potentials in the context of Quintessential Inflation ($\alpha$-QI), showing that the maximum value of the reheating temperature, independently of the value of the parameter $\alpha$, is near $10^9$ GeV. This result, which contradicts the usual belief that the reheating via the production of superheavy massive particles leads to an inefficient reheating temperature, is due to the fact that in our numerical calculations we take into account the contribution of the large wavelength modes to the reheating temperature, which never happens in analytical calculations where only ultraviolet modes are considered.
[ { "created": "Fri, 24 Dec 2021 08:26:25 GMT", "version": "v1" } ]
2021-12-28
[ [ "Saló", "Llibert Aresté", "" ], [ "de Haro", "Jaume", "" ] ]
We compute the gravitational production of conformally coupled superheavy particles during the phase transition from the end of inflation to the beginning of kination for $\alpha$-attractors potentials in the context of Quintessential Inflation ($\alpha$-QI), showing that the maximum value of the reheating temperature, independently of the value of the parameter $\alpha$, is near $10^9$ GeV. This result, which contradicts the usual belief that the reheating via the production of superheavy massive particles leads to an inefficient reheating temperature, is due to the fact that in our numerical calculations we take into account the contribution of the large wavelength modes to the reheating temperature, which never happens in analytical calculations where only ultraviolet modes are considered.
1603.09567
Tao Wang
Yun-Chao Wang, Towe Wang
Non-canonical two-field inflation to order $\xi^2$
24 pages, 6 figures, Appendix E added
null
null
null
gr-qc astro-ph.CO hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In non-canonical two-field inflation models, deviations from the canonical model can be captured by a parameter $\xi$. We show this parameter is usually one half of the slow-roll order and analytically calculate the primordial power spectra accurate to order $\xi^2$. The super-horizon perturbations are studied with an improved method, which gives a correction of order $\xi^2$. Three typical examples demonstrate that our analytical formulae of power spectra fit well with numerical simulation.
[ { "created": "Thu, 31 Mar 2016 12:58:56 GMT", "version": "v1" }, { "created": "Wed, 5 Oct 2016 09:30:09 GMT", "version": "v2" }, { "created": "Tue, 5 Dec 2017 01:32:48 GMT", "version": "v3" } ]
2017-12-06
[ [ "Wang", "Yun-Chao", "" ], [ "Wang", "Towe", "" ] ]
In non-canonical two-field inflation models, deviations from the canonical model can be captured by a parameter $\xi$. We show this parameter is usually one half of the slow-roll order and analytically calculate the primordial power spectra accurate to order $\xi^2$. The super-horizon perturbations are studied with an improved method, which gives a correction of order $\xi^2$. Three typical examples demonstrate that our analytical formulae of power spectra fit well with numerical simulation.
gr-qc/0612003
Janna Levin
Janna Levin
Chaos and Order in Models of Black Hole Pairs
null
Phys.Rev.D74:124027,2006
10.1103/PhysRevD.74.124027
null
gr-qc
null
Chaos in the orbits of black hole pairs has by now been confirmed by several independent groups. While the chaotic behavior of binary black hole orbits is no longer argued, it remains difficult to quantify the importance of chaos to the evolutionary dynamics of a pair of comparable mass black holes. None of our existing approximations are robust enough to offer convincing quantitative conclusions in the most highly nonlinear regime. It is intriguing to note that in three different approximations to a black hole pair built of a spinning black hole and a non-spinning companion, two approximations exhibit chaos and one approximation does not. The fully relativistic scenario of a spinning test-mass around a Schwarzschild black hole shows chaos, as does the Post-Newtonian Lagrangian approximation. However, the approximately equivalent Post-Newtonian Hamiltonian approximation does not show chaos when only one body spins. It is well known in dynamical systems theory that one system can be regular while an approximately related system is chaotic, so there is no formal conflict. However,the physical question remains, Is there chaos for comparable mass binaries when only one object spins? We are unable to answer this question given the poor convergence of the Post-Newtonian approximation to the fully relativistic system. A resolution awaits better approximations that can be trusted in the highly nonlinear regime.
[ { "created": "Fri, 1 Dec 2006 00:37:19 GMT", "version": "v1" } ]
2008-11-26
[ [ "Levin", "Janna", "" ] ]
Chaos in the orbits of black hole pairs has by now been confirmed by several independent groups. While the chaotic behavior of binary black hole orbits is no longer argued, it remains difficult to quantify the importance of chaos to the evolutionary dynamics of a pair of comparable mass black holes. None of our existing approximations are robust enough to offer convincing quantitative conclusions in the most highly nonlinear regime. It is intriguing to note that in three different approximations to a black hole pair built of a spinning black hole and a non-spinning companion, two approximations exhibit chaos and one approximation does not. The fully relativistic scenario of a spinning test-mass around a Schwarzschild black hole shows chaos, as does the Post-Newtonian Lagrangian approximation. However, the approximately equivalent Post-Newtonian Hamiltonian approximation does not show chaos when only one body spins. It is well known in dynamical systems theory that one system can be regular while an approximately related system is chaotic, so there is no formal conflict. However,the physical question remains, Is there chaos for comparable mass binaries when only one object spins? We are unable to answer this question given the poor convergence of the Post-Newtonian approximation to the fully relativistic system. A resolution awaits better approximations that can be trusted in the highly nonlinear regime.
2112.11945
Krishnanand K Nair
Krishnanand K. Nair and Mathew Thomas Arun
Kalb-Ramond field induced cosmological bounce in generalized teleparallel gravity
11 pages, 6 figures; Published version
Phys. Rev. D 105, 103505 (2022)
10.1103/PhysRevD.105.103505
null
gr-qc hep-th
http://creativecommons.org/licenses/by/4.0/
One of the important open questions in high-energy physics is to understand the lack of evidence of Kalb-Ramond (KR) field, in particular in the present day cosmology. In this paper we aim to address this issue by showing that a bounce scenario in the evolution of the Universe strongly advocates their elusiveness, even if their energy density was very large to start with. We consider the Kalb-Ramond field and its effects in the context of generalized teleparallel gravity in (3+1) dimensions. Teleparallel gravity is a description of gravitation in which the tetrads are the dynamical degrees of freedom, and the torsion arising from fields with spin are accommodated naturally as field strength tensors. In order to describe the coupling prescription, we address the correct generalization of the Fock-Ivanenko derivative operator for an n-form tensor field. By varying with respect to the tetrads, this rank-2 field is shown to source the teleparallel equivalent of Einstein's equations. We study the possibility of reproducing two well-known cosmological bounce scenarios, namely, symmetric bounce and matter bounce in four-dimensional spacetime with with the Friedmann-Lemaitre-Robertson-Walker metric and observe that the solution requires the KR field energy density to be localized near the bounce. The crucial result in our work is that this feature also naturally explains the lack of cosmological evidence of the rank-2 field in the present day Universe for the matter-bounce scenario. Thus, among the bouncing cosmologies, latter is favored over the former.
[ { "created": "Wed, 22 Dec 2021 15:08:58 GMT", "version": "v1" }, { "created": "Fri, 6 May 2022 06:26:32 GMT", "version": "v2" } ]
2022-05-09
[ [ "Nair", "Krishnanand K.", "" ], [ "Arun", "Mathew Thomas", "" ] ]
One of the important open questions in high-energy physics is to understand the lack of evidence of Kalb-Ramond (KR) field, in particular in the present day cosmology. In this paper we aim to address this issue by showing that a bounce scenario in the evolution of the Universe strongly advocates their elusiveness, even if their energy density was very large to start with. We consider the Kalb-Ramond field and its effects in the context of generalized teleparallel gravity in (3+1) dimensions. Teleparallel gravity is a description of gravitation in which the tetrads are the dynamical degrees of freedom, and the torsion arising from fields with spin are accommodated naturally as field strength tensors. In order to describe the coupling prescription, we address the correct generalization of the Fock-Ivanenko derivative operator for an n-form tensor field. By varying with respect to the tetrads, this rank-2 field is shown to source the teleparallel equivalent of Einstein's equations. We study the possibility of reproducing two well-known cosmological bounce scenarios, namely, symmetric bounce and matter bounce in four-dimensional spacetime with with the Friedmann-Lemaitre-Robertson-Walker metric and observe that the solution requires the KR field energy density to be localized near the bounce. The crucial result in our work is that this feature also naturally explains the lack of cosmological evidence of the rank-2 field in the present day Universe for the matter-bounce scenario. Thus, among the bouncing cosmologies, latter is favored over the former.
2407.14184
Changjun Gao
Changjun Gao and Jianhui Qiu
From the Janis-Newman-Winicour naked singularities to Einstein-Maxwell phantom wormholes
20 pages,3 figures
null
null
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The Janis-Newman-Winicour spacetime corresponds to a static spherically symmetric solution of Einstein equations with the energy momentum tensor of a massless quintessence field. It is understood that the spacetime describes a naked singularity. The solution has two parameters, $b$ and $s$. To our knowledge, the exact physical meaning of the two parameters is still unclear. In this paper, starting from the Janis-Newman-Winicour naked singularity solution, we first obtain a wormhole solution by a complex transformation. Then let the parameter $s$ approaching infinity, we obtain the well-known exponential wormhole solution. After that, we embed both the Janis-Newman-Winicour naked singularity and its wormhole counterpart in the background of de Sitter or anti-de Sitter Universe with the energy momentum tensor of massive quintessence and massive phantom fields, respectively. To our surprise, the resulting quintessence potential is actually the dilaton potential found by one of us. It hints us that, by modulating the parameters in the charged dilaton black hole solutions we can get the Janis-Newman-Winicour solution. Furthermore, a charged wormhole solution is obtained by performing complex transformation on the charged dilaton black hole solutions in the background of de Sitter or anti-de Sitter Universe. We eventually find that $s$ is actually related to the coupling constant of dilaton field to Maxwell field and $b$ is related to a negative mass for the dilaton black holes. A negative black hole mass is physically forbidden. Therefore, we conclude that the Janis-Newman-Winicour naked singularity solution is not physically allowed.
[ { "created": "Fri, 19 Jul 2024 10:28:31 GMT", "version": "v1" }, { "created": "Mon, 22 Jul 2024 11:54:04 GMT", "version": "v2" } ]
2024-07-23
[ [ "Gao", "Changjun", "" ], [ "Qiu", "Jianhui", "" ] ]
The Janis-Newman-Winicour spacetime corresponds to a static spherically symmetric solution of Einstein equations with the energy momentum tensor of a massless quintessence field. It is understood that the spacetime describes a naked singularity. The solution has two parameters, $b$ and $s$. To our knowledge, the exact physical meaning of the two parameters is still unclear. In this paper, starting from the Janis-Newman-Winicour naked singularity solution, we first obtain a wormhole solution by a complex transformation. Then let the parameter $s$ approaching infinity, we obtain the well-known exponential wormhole solution. After that, we embed both the Janis-Newman-Winicour naked singularity and its wormhole counterpart in the background of de Sitter or anti-de Sitter Universe with the energy momentum tensor of massive quintessence and massive phantom fields, respectively. To our surprise, the resulting quintessence potential is actually the dilaton potential found by one of us. It hints us that, by modulating the parameters in the charged dilaton black hole solutions we can get the Janis-Newman-Winicour solution. Furthermore, a charged wormhole solution is obtained by performing complex transformation on the charged dilaton black hole solutions in the background of de Sitter or anti-de Sitter Universe. We eventually find that $s$ is actually related to the coupling constant of dilaton field to Maxwell field and $b$ is related to a negative mass for the dilaton black holes. A negative black hole mass is physically forbidden. Therefore, we conclude that the Janis-Newman-Winicour naked singularity solution is not physically allowed.
gr-qc/0312064
Marcelo J. Reboucas
M.J. Reboucas, J. Santos, A.F.F. Teixeira
Classification of Energy Momentum Tensors in $n \geq 5$ Dimensional Space-times: a Review
LaTex2e, 18 pages. To appear in Braz.J.Phys (2004)
Braz.J.Phys. 34 (2004) 535-543
10.1590/S0103-97332004000300034
null
gr-qc astro-ph hep-th
null
Recent developments in string theory suggest that there might exist extra spatial dimensions, which are not small nor compact. The framework of a great number of brane cosmological models is that in which the matter fields are confined on a brane-world embedded in five dimensions (the bulk). Motivated by this we review the main results on the algebraic classification of second order symmetric tensors in 5-dimensional space-times. All possible Segre types for a symmetric two-tensor are found, and a set of canonical forms for each Segre type is obtained. A limiting diagram for the Segre types of these symmetric tensors in 5-D is built. Two theorems which collect together some basic results on the algebraic structure of second order symmetric tensors in 5-D are presented. We also show how one can obtain, by induction, the classification and the canonical forms of a symmetric two-tensor on n-dimensional (n > 5) spaces from its classification in 5-D spaces, present the Segre types in n-D and the corresponding canonical forms. This classification of symmetric two-tensors in any n-D spaces and their canonical forms are important in the context of n-dimensional brane-worlds context and also in the framework of 11-D supergravity and 10-D superstrings.
[ { "created": "Fri, 12 Dec 2003 01:51:45 GMT", "version": "v1" } ]
2015-06-25
[ [ "Reboucas", "M. J.", "" ], [ "Santos", "J.", "" ], [ "Teixeira", "A. F. F.", "" ] ]
Recent developments in string theory suggest that there might exist extra spatial dimensions, which are not small nor compact. The framework of a great number of brane cosmological models is that in which the matter fields are confined on a brane-world embedded in five dimensions (the bulk). Motivated by this we review the main results on the algebraic classification of second order symmetric tensors in 5-dimensional space-times. All possible Segre types for a symmetric two-tensor are found, and a set of canonical forms for each Segre type is obtained. A limiting diagram for the Segre types of these symmetric tensors in 5-D is built. Two theorems which collect together some basic results on the algebraic structure of second order symmetric tensors in 5-D are presented. We also show how one can obtain, by induction, the classification and the canonical forms of a symmetric two-tensor on n-dimensional (n > 5) spaces from its classification in 5-D spaces, present the Segre types in n-D and the corresponding canonical forms. This classification of symmetric two-tensors in any n-D spaces and their canonical forms are important in the context of n-dimensional brane-worlds context and also in the framework of 11-D supergravity and 10-D superstrings.
1711.05539
Giulia Gubitosi
Giulia Gubitosi, Joao Magueijo
Primordial standing waves
null
Phys. Rev. D 97, 063509 (2018)
10.1103/PhysRevD.97.063509
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We consider the possibility that the primordial fluctuations (scalar and tensor) might have been standing waves at their moment of creation, whether or not they had a quantum origin. We lay down the general conditions for spatial translational invariance, and isolate the pieces of the most general such theory that comply with, or break translational symmetry. We find that, in order to characterize statistically translationally invariant standing waves, it is essential to consider the correlator $\langle c_0({\mathbf k}) c_0({\mathbf k}')\rangle$ in addition to the better known $\langle c_0({\mathbf k}) c_0^\dagger({\mathbf k}')\rangle$ (where $c_0({\mathbf k})$ are the complex amplitudes of travelling waves). We then examine how the standard process of "squeezing" (responsible for converting travelling waves into standing waves while the fluctuations are outside the horizon) reacts to being fed primordial standing waves. For translationally invariant systems only one type of standing wave, with the correct temporal phase (the "sine wave"), survives squeezing. Primordial standing waves might therefore be invisible at late times -- or not -- depending on their phase. Theories with modified dispersion relations behave differently in this respect, since only standing waves with the opposite temporal phase survive at late times.
[ { "created": "Wed, 15 Nov 2017 12:45:29 GMT", "version": "v1" } ]
2018-03-21
[ [ "Gubitosi", "Giulia", "" ], [ "Magueijo", "Joao", "" ] ]
We consider the possibility that the primordial fluctuations (scalar and tensor) might have been standing waves at their moment of creation, whether or not they had a quantum origin. We lay down the general conditions for spatial translational invariance, and isolate the pieces of the most general such theory that comply with, or break translational symmetry. We find that, in order to characterize statistically translationally invariant standing waves, it is essential to consider the correlator $\langle c_0({\mathbf k}) c_0({\mathbf k}')\rangle$ in addition to the better known $\langle c_0({\mathbf k}) c_0^\dagger({\mathbf k}')\rangle$ (where $c_0({\mathbf k})$ are the complex amplitudes of travelling waves). We then examine how the standard process of "squeezing" (responsible for converting travelling waves into standing waves while the fluctuations are outside the horizon) reacts to being fed primordial standing waves. For translationally invariant systems only one type of standing wave, with the correct temporal phase (the "sine wave"), survives squeezing. Primordial standing waves might therefore be invisible at late times -- or not -- depending on their phase. Theories with modified dispersion relations behave differently in this respect, since only standing waves with the opposite temporal phase survive at late times.
gr-qc/9305005
null
Nguyen Hong Chuong and Nguyen Van Hoang
Cosmological Constant and Gravitational Repulsion Effect: 1. Homogeneous models with radiation
REVTEX, 11 pages, Syracuse University preprint SU-GP-93/5-1
Int.J.Mod.Phys. D2 (1993) 443-450
10.1142/S0218271893000313
null
gr-qc astro-ph
null
Within the framework of the minimum quadratic Poincare gauge theory of gravity in the Riemann-Cartan spacetime we study the influence of gravitational vacuum energy density (a cosmological constant) on the dynamics of various gravitating systems. It is shown that the inclusion of the cosmological term can lead to gravitational repulsion. For some simple cases of spatially homogeneous cosmological models with radiation we obtain non-singular solutions in form of elementary functions and elliptic integrals.
[ { "created": "Thu, 6 May 1993 23:45:00 GMT", "version": "v1" } ]
2009-10-22
[ [ "Chuong", "Nguyen Hong", "" ], [ "Van Hoang", "Nguyen", "" ] ]
Within the framework of the minimum quadratic Poincare gauge theory of gravity in the Riemann-Cartan spacetime we study the influence of gravitational vacuum energy density (a cosmological constant) on the dynamics of various gravitating systems. It is shown that the inclusion of the cosmological term can lead to gravitational repulsion. For some simple cases of spatially homogeneous cosmological models with radiation we obtain non-singular solutions in form of elementary functions and elliptic integrals.
1512.04037
Junji Jia
Xionghui Liu, Nan Yang, Junji Jia
Gravitational lensing of massive particles in Schwarzschild gravity
typos corrected. One formula re-written. To match the published version
Class. Quantum Grav. 33 (2016) 175014
10.1088/0264-9381/33/17/175014
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Both massless light ray and objects with nonzero mass experience trajectory bending in a gravitational field. In this work the bending of trajectories of massive objects in a Schwarzschild spacetime and the corresponding gravitational lensing (GL) effects are studied. A particle sphere for Schwarzschild black hole (BH) is found with its radius a simple function of the particle velocity and proportional to the BH mass. A single master formula for both the massless and massive particle bending angle is found, in the form of an elliptic function depending only on the velocity and impact parameter. This bending angle is expanded in both large and small velocity limits and large and small impact parameter limits. The corresponding deflection angle for weak and strong GL of massive particles are analyzed, and their corrections to the light ray deflection angles are obtained. The dependence of the deflection angles on the source angle and the particle speed is investigated. Finally we discuss the potential applications of the results in hypervelocity star observations and in determining mass/mass hierarchy of slow particles/objects.
[ { "created": "Sun, 13 Dec 2015 11:36:50 GMT", "version": "v1" }, { "created": "Thu, 1 Sep 2016 14:40:41 GMT", "version": "v2" } ]
2016-09-02
[ [ "Liu", "Xionghui", "" ], [ "Yang", "Nan", "" ], [ "Jia", "Junji", "" ] ]
Both massless light ray and objects with nonzero mass experience trajectory bending in a gravitational field. In this work the bending of trajectories of massive objects in a Schwarzschild spacetime and the corresponding gravitational lensing (GL) effects are studied. A particle sphere for Schwarzschild black hole (BH) is found with its radius a simple function of the particle velocity and proportional to the BH mass. A single master formula for both the massless and massive particle bending angle is found, in the form of an elliptic function depending only on the velocity and impact parameter. This bending angle is expanded in both large and small velocity limits and large and small impact parameter limits. The corresponding deflection angle for weak and strong GL of massive particles are analyzed, and their corrections to the light ray deflection angles are obtained. The dependence of the deflection angles on the source angle and the particle speed is investigated. Finally we discuss the potential applications of the results in hypervelocity star observations and in determining mass/mass hierarchy of slow particles/objects.
gr-qc/0512160
Emanuele Berti
Emanuele Berti, Vitor Cardoso, Clifford M. Will
On gravitational-wave spectroscopy of massive black holes with the space interferometer LISA
44 pages, 21 figures, 10 tables. Minor changes to match version in press in Phys. Rev. D
Phys.Rev.D73:064030,2006
10.1103/PhysRevD.73.064030
null
gr-qc astro-ph hep-th
null
Newly formed black holes are expected to emit characteristic radiation in the form of quasi-normal modes, called ringdown waves, with discrete frequencies. LISA should be able to detect the ringdown waves emitted by oscillating supermassive black holes throughout the observable Universe. We develop a multi-mode formalism, applicable to any interferometric detectors, for detecting ringdown signals, for estimating black hole parameters from those signals, and for testing the no-hair theorem of general relativity. Focusing on LISA, we use current models of its sensitivity to compute the expected signal-to-noise ratio for ringdown events, the relative parameter estimation accuracy, and the resolvability of different modes. We also discuss the extent to which uncertainties on physical parameters, such as the black hole spin and the energy emitted in each mode, will affect our ability to do black hole spectroscopy.
[ { "created": "Thu, 29 Dec 2005 02:27:13 GMT", "version": "v1" }, { "created": "Tue, 21 Mar 2006 15:41:15 GMT", "version": "v2" } ]
2008-11-26
[ [ "Berti", "Emanuele", "" ], [ "Cardoso", "Vitor", "" ], [ "Will", "Clifford M.", "" ] ]
Newly formed black holes are expected to emit characteristic radiation in the form of quasi-normal modes, called ringdown waves, with discrete frequencies. LISA should be able to detect the ringdown waves emitted by oscillating supermassive black holes throughout the observable Universe. We develop a multi-mode formalism, applicable to any interferometric detectors, for detecting ringdown signals, for estimating black hole parameters from those signals, and for testing the no-hair theorem of general relativity. Focusing on LISA, we use current models of its sensitivity to compute the expected signal-to-noise ratio for ringdown events, the relative parameter estimation accuracy, and the resolvability of different modes. We also discuss the extent to which uncertainties on physical parameters, such as the black hole spin and the energy emitted in each mode, will affect our ability to do black hole spectroscopy.
gr-qc/0109088
Anand S. Sengupta
Anand S. Sengupta (1), Sanjeev V. Dhurandhar (1), Albert Lazzarini (2) and Tom Prince (3) ((1) IUCAA, Pune, India (2) LIGO Laboratory, Caltech (3) Jet Propulsion Laboratory, Caltech)
Extended hierarchical search (EHS) algorithm for detection of gravitational waves from inspiraling compact binaries
6 pages, 6 EPS figures, uses CQG style iopart.cls
Class.Quant.Grav. 19 (2002) 1507-1512
10.1088/0264-9381/19/7/337
IUCAA-42/2001, LIGO-P010020-00-E
gr-qc
null
Pattern matching techniques like matched filtering will be used for online extraction of gravitational wave signals buried inside detector noise. This involves cross correlating the detector output with hundreds of thousands of templates spanning a multi-dimensional parameter space, which is very expensive computationally. A faster implementation algorithm was devised by Mohanty and Dhurandhar [1996] using a hierarchy of templates over the mass parameters, which speeded up the procedure by about 25 to 30 times. We show that a further reduction in computational cost is possible if we extend the hierarchy paradigm to an extra parameter, namely, the time of arrival of the signal. In the first stage, the chirp waveform is cut-off at a relatively low frequency allowing the data to be coarsely sampled leading to cost saving in performing the FFTs. This is possible because most of the signal power is at low frequencies, and therefore the advantage due to hierarchy over masses is not compromised. Results are obtained for spin-less templates up to the second post-Newtonian (2PN) order for a single detector with LIGO I noise power spectral density. We estimate that the gain in computational cost over a flat search is about 100.
[ { "created": "Thu, 27 Sep 2001 11:13:33 GMT", "version": "v1" } ]
2009-11-07
[ [ "Sengupta", "Anand S.", "" ], [ "Dhurandhar", "Sanjeev V.", "" ], [ "Lazzarini", "Albert", "" ], [ "Prince", "Tom", "" ] ]
Pattern matching techniques like matched filtering will be used for online extraction of gravitational wave signals buried inside detector noise. This involves cross correlating the detector output with hundreds of thousands of templates spanning a multi-dimensional parameter space, which is very expensive computationally. A faster implementation algorithm was devised by Mohanty and Dhurandhar [1996] using a hierarchy of templates over the mass parameters, which speeded up the procedure by about 25 to 30 times. We show that a further reduction in computational cost is possible if we extend the hierarchy paradigm to an extra parameter, namely, the time of arrival of the signal. In the first stage, the chirp waveform is cut-off at a relatively low frequency allowing the data to be coarsely sampled leading to cost saving in performing the FFTs. This is possible because most of the signal power is at low frequencies, and therefore the advantage due to hierarchy over masses is not compromised. Results are obtained for spin-less templates up to the second post-Newtonian (2PN) order for a single detector with LIGO I noise power spectral density. We estimate that the gain in computational cost over a flat search is about 100.
gr-qc/0109022
Nora Breton
Nora Breton
Born-Infeld generalization of the Reissner-Nordstrom black hole
16 pages, latex, 6 postscript figures
null
null
null
gr-qc
null
In this work we study the trajectories of test particles in a geometry that is the nonlinear electromagnetic generalization of the Reissner-Nordstrom solution. The studied spacetime is a Einstein-Born-Infeld solution, nonsingular outside a regular event horizon and characterized by three parameters: mass $M$, charge $Q$ and the Born-Infeld parameter $b$ related to the magnitude of the electric field at the origin. Asymptotically it is a Reissner-Nordstrom solution
[ { "created": "Thu, 6 Sep 2001 15:10:14 GMT", "version": "v1" } ]
2007-05-23
[ [ "Breton", "Nora", "" ] ]
In this work we study the trajectories of test particles in a geometry that is the nonlinear electromagnetic generalization of the Reissner-Nordstrom solution. The studied spacetime is a Einstein-Born-Infeld solution, nonsingular outside a regular event horizon and characterized by three parameters: mass $M$, charge $Q$ and the Born-Infeld parameter $b$ related to the magnitude of the electric field at the origin. Asymptotically it is a Reissner-Nordstrom solution
gr-qc/0607120
Jose M. M. Senovilla
Jos\'e M.M. Senovilla
Symmetric hyperbolic systems for a large class of fields in arbitrary dimension
24 pages, no figures
Gen.Rel.Grav.39:361-386,2007
10.1007/s10714-006-0390-2
null
gr-qc
null
Symmetric hyperbolic systems of equations are explicitly constructed for a general class of tensor fields by considering their structure as r-fold forms. The hyperbolizations depend on 2r-1 arbitrary timelike vectors. The importance of the so-called "superenergy" tensors, which provide the necessary symmetric positive matrices, is emphasized and made explicit. Thereby, a unified treatment of many physical systems is achieved, as well as of the sometimes called "higher order" systems. The characteristics of these symmetric hyperbolic systems are always physical, and directly related to the null directions of the superenergy tensor, which are in particular principal null directions of the tensor field solutions. Generic energy estimates and inequalities are presented too.
[ { "created": "Wed, 26 Jul 2006 16:32:51 GMT", "version": "v1" } ]
2008-11-26
[ [ "Senovilla", "José M. M.", "" ] ]
Symmetric hyperbolic systems of equations are explicitly constructed for a general class of tensor fields by considering their structure as r-fold forms. The hyperbolizations depend on 2r-1 arbitrary timelike vectors. The importance of the so-called "superenergy" tensors, which provide the necessary symmetric positive matrices, is emphasized and made explicit. Thereby, a unified treatment of many physical systems is achieved, as well as of the sometimes called "higher order" systems. The characteristics of these symmetric hyperbolic systems are always physical, and directly related to the null directions of the superenergy tensor, which are in particular principal null directions of the tensor field solutions. Generic energy estimates and inequalities are presented too.
2205.13513
Agata Trovato
P. Bacon, A. Trovato, M. Bejger
Denoising gravitational-wave signals from binary black holes with dilated convolutional autoencoder
27 pages, 5 figures in the text and 7 in the appendix
null
null
null
gr-qc astro-ph.IM
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Broadband frequency output of gravitational-wave detectors is a non-stationary and non-Gaussian time series data stream dominated by noise populated by local disturbances and transient artifacts, which evolve on the same timescale as the gravitational-wave signals and may corrupt the astrophysical information. We study a denoising algorithm dedicated to expose the astrophysical signals by employing a convolutional neural network in the encoder-decoder configuration, i.e. apply the denoising procedure of coalescing binary black hole signals in the publicly available LIGO O1 time series strain data. The denoising convolutional autoencoder neural network is trained on a dataset of simulated astrophysical signals injected into the real detector's noise and a dataset of detector noise artifacts ("glitches"), and its fidelity is tested on real gravitational-wave events from O1 and O2 LIGO-Virgo observing runs.
[ { "created": "Thu, 26 May 2022 17:32:25 GMT", "version": "v1" } ]
2022-05-27
[ [ "Bacon", "P.", "" ], [ "Trovato", "A.", "" ], [ "Bejger", "M.", "" ] ]
Broadband frequency output of gravitational-wave detectors is a non-stationary and non-Gaussian time series data stream dominated by noise populated by local disturbances and transient artifacts, which evolve on the same timescale as the gravitational-wave signals and may corrupt the astrophysical information. We study a denoising algorithm dedicated to expose the astrophysical signals by employing a convolutional neural network in the encoder-decoder configuration, i.e. apply the denoising procedure of coalescing binary black hole signals in the publicly available LIGO O1 time series strain data. The denoising convolutional autoencoder neural network is trained on a dataset of simulated astrophysical signals injected into the real detector's noise and a dataset of detector noise artifacts ("glitches"), and its fidelity is tested on real gravitational-wave events from O1 and O2 LIGO-Virgo observing runs.
2301.11439
Theodoros Papanikolaou
Theodoros Papanikolaou
Primordial black holes in loop quantum cosmology: The effect on the threshold
Accepted in Classical and Quantum Gravity
null
10.1088/1361-6382/acd97d
null
gr-qc astro-ph.CO hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Primordial black holes form in the early Universe and constitute one of the most viable candidates for dark matter. The study of their formation process requires the determination of a critical energy density perturbation threshold $\delta_\mathrm{c}$, which in general depends on the underlying gravity theory. Up to now, the majority of analytic and numerical techniques calculate $\delta_\mathrm{c}$ within the framework of general relativity. In this work, using simple physical arguments we estimate semi-analytically the PBH formation threshold within the framework of quantum gravity, working for concreteness within loop quantum cosmology (LQC). In particular, for low mass PBHs formed close to the quantum bounce, we find a reduction in the value of $\delta_\mathrm{c}$ up to $50\%$ compared to the general relativistic regime quantifying for the first time to the best of our knowledge how quantum effects can influence PBH formation within a quantum gravity framework. Finally, by varying the Barbero-Immirzi parameter $\gamma$ of loop quantum gravity (LQG) we show its effect on the value of $\delta_\mathrm{c}$ while using the observational/phenomenological signatures associated to ultra-light PBHs, namely the ones affected by LQG effects, we propose the PBH portal as a novel probe to constrain the potential quantum nature of gravity.
[ { "created": "Thu, 26 Jan 2023 21:57:05 GMT", "version": "v1" }, { "created": "Fri, 26 May 2023 13:29:08 GMT", "version": "v2" } ]
2023-06-21
[ [ "Papanikolaou", "Theodoros", "" ] ]
Primordial black holes form in the early Universe and constitute one of the most viable candidates for dark matter. The study of their formation process requires the determination of a critical energy density perturbation threshold $\delta_\mathrm{c}$, which in general depends on the underlying gravity theory. Up to now, the majority of analytic and numerical techniques calculate $\delta_\mathrm{c}$ within the framework of general relativity. In this work, using simple physical arguments we estimate semi-analytically the PBH formation threshold within the framework of quantum gravity, working for concreteness within loop quantum cosmology (LQC). In particular, for low mass PBHs formed close to the quantum bounce, we find a reduction in the value of $\delta_\mathrm{c}$ up to $50\%$ compared to the general relativistic regime quantifying for the first time to the best of our knowledge how quantum effects can influence PBH formation within a quantum gravity framework. Finally, by varying the Barbero-Immirzi parameter $\gamma$ of loop quantum gravity (LQG) we show its effect on the value of $\delta_\mathrm{c}$ while using the observational/phenomenological signatures associated to ultra-light PBHs, namely the ones affected by LQG effects, we propose the PBH portal as a novel probe to constrain the potential quantum nature of gravity.
1701.07444
Ram Brustein
Ram Brustein, A.J.M. Medved, K. Yagi
Discovering the interior of black holes
Added author, added discussion of detectability, clarified conclusions, 32 pages, 3 figures. V3 agrees with the accepted version - minor revisions
Phys. Rev. D 96, 124021 (2017)
10.1103/PhysRevD.96.124021
null
gr-qc astro-ph.HE hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The detection of gravitational waves (GWs) from black hole (BH) mergers provides an inroad toward probing the interior of astrophysical BHs. The general-relativistic description of the BH interior is that of empty spacetime with a (possibly) singular core. Recently, however, the hypothesis that the BH interior does not exist has been gaining traction, as it provides a means for resolving the BH information-loss problem. Here, we propose a simple method for answering the following question: Does the BH interior exist and, if so, does it contain some distribution of matter or is it mostly empty? Our proposal is premised on the idea that, similar to the case of relativistic, ultra-compact stars, any BH-like object whose interior has some matter distribution should support fluid modes in addition to the conventional spacetime modes. In particular, the Coriolis-induced Rossby (r-) modes, whose spectrum is mostly insensitive to the composition of the interior matter, should be a universal feature of such BH-like objects. In fact, the frequency and damping time of these modes are determined by only the object's mass and speed of rotation. The r-modes oscillate at a lower frequency, decay at a slower rate and produce weaker GWs than do modes of the spacetime class. Hence, they imprint a model-insensitive signature of a non-empty interior in the GW spectrum resulting from a BH merger. We find that future GW detectors, such as Advanced LIGO with its design sensitivity, have the potential of detecting such r-modes if the amount of GWs leaking out quantum mechanically from the interior of a BH-like object is sufficiently large.
[ { "created": "Wed, 25 Jan 2017 19:01:11 GMT", "version": "v1" }, { "created": "Fri, 26 May 2017 09:00:17 GMT", "version": "v2" }, { "created": "Tue, 5 Dec 2017 07:26:37 GMT", "version": "v3" } ]
2017-12-27
[ [ "Brustein", "Ram", "" ], [ "Medved", "A. J. M.", "" ], [ "Yagi", "K.", "" ] ]
The detection of gravitational waves (GWs) from black hole (BH) mergers provides an inroad toward probing the interior of astrophysical BHs. The general-relativistic description of the BH interior is that of empty spacetime with a (possibly) singular core. Recently, however, the hypothesis that the BH interior does not exist has been gaining traction, as it provides a means for resolving the BH information-loss problem. Here, we propose a simple method for answering the following question: Does the BH interior exist and, if so, does it contain some distribution of matter or is it mostly empty? Our proposal is premised on the idea that, similar to the case of relativistic, ultra-compact stars, any BH-like object whose interior has some matter distribution should support fluid modes in addition to the conventional spacetime modes. In particular, the Coriolis-induced Rossby (r-) modes, whose spectrum is mostly insensitive to the composition of the interior matter, should be a universal feature of such BH-like objects. In fact, the frequency and damping time of these modes are determined by only the object's mass and speed of rotation. The r-modes oscillate at a lower frequency, decay at a slower rate and produce weaker GWs than do modes of the spacetime class. Hence, they imprint a model-insensitive signature of a non-empty interior in the GW spectrum resulting from a BH merger. We find that future GW detectors, such as Advanced LIGO with its design sensitivity, have the potential of detecting such r-modes if the amount of GWs leaking out quantum mechanically from the interior of a BH-like object is sufficiently large.
1804.08079
Tiberiu Harko
Xiaoyue Zhang, Man Ho Chan, Tiberiu Harko, Shi-Dong Liang, Chun Sing Leung
Slowly rotating Bose Einstein Condensate galactic dark matter halos, and their rotation curves
22 pages, 7 figures, accepted for publication in EPJC
The European Physical Journal C 78, 346 (2018)
10.1140/epjc/s10052-018-5835-8
null
gr-qc astro-ph.GA hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
If dark matter is composed of massive bosons, a Bose-Einstein Condensation process must have occurred during the cosmological evolution. Therefore galactic dark matter may be in a form of a condensate, characterized by a strong self-interaction. We consider the effects of rotation on the Bose-Einstein Condensate dark matter halos, and we investigate how rotation might influence their astrophysical properties. In order to describe the condensate we use the Gross-Pitaevskii equation, and the Thomas-Fermi approximation, which predicts a polytropic equation of state with polytropic index $n=1$. By assuming a rigid body rotation for the halo, with the use of the hydrodynamic representation of the Gross-Pitaevskii equation we obtain the basic equation describing the density distribution of the rotating condensate. We obtain the general solutions for the condensed dark matter density, and we derive the general representations for the mass distribution, boundary (radius), potential energy, velocity dispersion, tangential velocity and for the logarithmic density and velocity slopes, respectively. Explicit expressions for the radius, mass, and tangential velocity are obtained in the first order of approximation, under the assumption of slow rotation. In order to compare our results with the observations we fit the theoretical expressions of the tangential velocity of massive test particles moving in rotating Bose-Einstein Condensate dark halos with the data of 12 dwarf galaxies, and the Milky Way, respectively.
[ { "created": "Sun, 22 Apr 2018 07:38:58 GMT", "version": "v1" } ]
2018-07-24
[ [ "Zhang", "Xiaoyue", "" ], [ "Chan", "Man Ho", "" ], [ "Harko", "Tiberiu", "" ], [ "Liang", "Shi-Dong", "" ], [ "Leung", "Chun Sing", "" ] ]
If dark matter is composed of massive bosons, a Bose-Einstein Condensation process must have occurred during the cosmological evolution. Therefore galactic dark matter may be in a form of a condensate, characterized by a strong self-interaction. We consider the effects of rotation on the Bose-Einstein Condensate dark matter halos, and we investigate how rotation might influence their astrophysical properties. In order to describe the condensate we use the Gross-Pitaevskii equation, and the Thomas-Fermi approximation, which predicts a polytropic equation of state with polytropic index $n=1$. By assuming a rigid body rotation for the halo, with the use of the hydrodynamic representation of the Gross-Pitaevskii equation we obtain the basic equation describing the density distribution of the rotating condensate. We obtain the general solutions for the condensed dark matter density, and we derive the general representations for the mass distribution, boundary (radius), potential energy, velocity dispersion, tangential velocity and for the logarithmic density and velocity slopes, respectively. Explicit expressions for the radius, mass, and tangential velocity are obtained in the first order of approximation, under the assumption of slow rotation. In order to compare our results with the observations we fit the theoretical expressions of the tangential velocity of massive test particles moving in rotating Bose-Einstein Condensate dark halos with the data of 12 dwarf galaxies, and the Milky Way, respectively.
2210.00781
Boris Latosh
Boris N. Latosh
Scalaron Decay in Perturbative Quantum Gravity
null
J. Exp. Theor. Phys. 136, 555 (2023)
10.1134/S1063776123050023
null
gr-qc hep-th
http://creativecommons.org/licenses/by/4.0/
A certain quadratic gravity model provides a successfully inflationary scenario. The inflation is driven by the new scalar degree of freedom called scalaron. After the end of inflation the scalaron decays in matter and dark matter degrees of freedom reheating the Universe. We study new channels by which the scalaron can transfer energy to the matter sector. These channels are annihilation and decay via intermediate graviton states. Results are obtained within perturbative quantum gravity. In the heavy scalaron limit only scalar particles are produced by the annihilation channel. Scalaron decays in all types of particles are allowed. In the light scalaron limit decay channel is strongly suppressed. Boson production via the annihilation channel is expected to be dominant at the early stages of reheating, while fermion production will dominate later stages.
[ { "created": "Mon, 3 Oct 2022 09:36:59 GMT", "version": "v1" } ]
2023-06-21
[ [ "Latosh", "Boris N.", "" ] ]
A certain quadratic gravity model provides a successfully inflationary scenario. The inflation is driven by the new scalar degree of freedom called scalaron. After the end of inflation the scalaron decays in matter and dark matter degrees of freedom reheating the Universe. We study new channels by which the scalaron can transfer energy to the matter sector. These channels are annihilation and decay via intermediate graviton states. Results are obtained within perturbative quantum gravity. In the heavy scalaron limit only scalar particles are produced by the annihilation channel. Scalaron decays in all types of particles are allowed. In the light scalaron limit decay channel is strongly suppressed. Boson production via the annihilation channel is expected to be dominant at the early stages of reheating, while fermion production will dominate later stages.
gr-qc/0501067
Bijan Saha
Bijan Saha
Anisotropic cosmological models with perfect fluid and dark energy revisited
RevTex, 9 pages, 8 figures
Int.J.Theor.Phys. 45 (2006) 952-964
10.1007/s10773-006-9089-0
null
gr-qc
null
We consider a self-consistent system of Bianchi type-I (BI) gravitational field and a binary mixture of perfect fluid and dark energy. The perfect fluid is taken to be the one obeying the usual equation of state, i.e., $p = \zeta \ve$, with $\zeta \in [0, 1]$ whereas, the dark energy is considered to be obeying a quintessence-like equation of state. Exact solutions to the corresponding Einstein equations are obtained. The model in consideration gives rise to a Universe which is spatially finite. Depending on the choice of problem parameters the Universe is either close with a space-time singularity, or an open one which is oscillatory, regular and infinite in time.
[ { "created": "Fri, 21 Jan 2005 12:22:54 GMT", "version": "v1" } ]
2015-05-01
[ [ "Saha", "Bijan", "" ] ]
We consider a self-consistent system of Bianchi type-I (BI) gravitational field and a binary mixture of perfect fluid and dark energy. The perfect fluid is taken to be the one obeying the usual equation of state, i.e., $p = \zeta \ve$, with $\zeta \in [0, 1]$ whereas, the dark energy is considered to be obeying a quintessence-like equation of state. Exact solutions to the corresponding Einstein equations are obtained. The model in consideration gives rise to a Universe which is spatially finite. Depending on the choice of problem parameters the Universe is either close with a space-time singularity, or an open one which is oscillatory, regular and infinite in time.
2209.15047
Philip D. Mannheim
Philip D. Mannheim
How to quantize gravity and how not to quantize gravity
Extended version 34 pages. Uses sn-jnl.cls. Prepared for a Special Issue in the European Physical Journal Plus on "Higher Derivatives in Quantum Gravity: Theory, Tests, and Phenomenology"
null
null
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Taking the quantization of electromagnetism as the paradigm, we show how this procedure cannot work for Einstein gravity. However, it does work for conformal gravity, a fourth-order derivative, renormalizable theory of gravity that Bender and Mannheim have shown to be ghost free. We show that in any gravity theory gravity cannot be quantized canonically. Rather, because of an interplay between the zero-point energy of gravity and that of its matter source, gravity is quantized purely by its coupling to a quantized matter source, with gravity being intrinsically quantum mechanical. Treating the zero-point energy this way provides a solution to the cosmological constant problem. With the gravitational zero-point energy issue having been ignored in standard Einstein gravity, it is not possible to solve the cosmological constant problem in standard gravity, since without the zero-point contribution gravity does not know where the zero of energy is.
[ { "created": "Thu, 29 Sep 2022 18:43:49 GMT", "version": "v1" }, { "created": "Mon, 16 Jan 2023 02:34:47 GMT", "version": "v2" } ]
2023-01-18
[ [ "Mannheim", "Philip D.", "" ] ]
Taking the quantization of electromagnetism as the paradigm, we show how this procedure cannot work for Einstein gravity. However, it does work for conformal gravity, a fourth-order derivative, renormalizable theory of gravity that Bender and Mannheim have shown to be ghost free. We show that in any gravity theory gravity cannot be quantized canonically. Rather, because of an interplay between the zero-point energy of gravity and that of its matter source, gravity is quantized purely by its coupling to a quantized matter source, with gravity being intrinsically quantum mechanical. Treating the zero-point energy this way provides a solution to the cosmological constant problem. With the gravitational zero-point energy issue having been ignored in standard Einstein gravity, it is not possible to solve the cosmological constant problem in standard gravity, since without the zero-point contribution gravity does not know where the zero of energy is.
gr-qc/9310018
Mourad
J. Mourad
Space-time events and relativistic particle localization
13 pages, LPTHE 93/41
null
null
null
gr-qc hep-th
null
A relation expressing the covariant transformation properties of a relativistic position operator is derived. This relation differs from the one existing in the literature expressing manifest covariance by some factor ordering. The relation is derived in order for the localization of a particle to represent a space-time event. It is shown that there exists a conflict between this relation and the hermiticity of a positive energy position operator.
[ { "created": "Mon, 11 Oct 1993 19:04:52 GMT", "version": "v1" } ]
2007-05-23
[ [ "Mourad", "J.", "" ] ]
A relation expressing the covariant transformation properties of a relativistic position operator is derived. This relation differs from the one existing in the literature expressing manifest covariance by some factor ordering. The relation is derived in order for the localization of a particle to represent a space-time event. It is shown that there exists a conflict between this relation and the hermiticity of a positive energy position operator.
1405.2277
Serguei Krasnikov
S. Krasnikov
Time machines with the compactly determined Cauchy horizon
A few minor amendments
Phys. Rev. D90 (2014) 024067
10.1103/PhysRevD.90.024067
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The building of a time machine, if possible at all, requires the relevant regions of spacetime to be compact (that is, physically speaking, free from sources of unpredictability such as infinities and singularities). Motivated by this argument we consider the spacetimes with the compactly determined Cauchy horizons (CDCHs), the defining property of which is the compactness of $\overline{J^-(\EuScript U)}\cap J^+(\EuScript S_0)$, where $\EuScript U$ is an open subset of the Cauchy horizon and $\EuScript S_0$ is a Cauchy surface of the initial globally hyperbolic region $\ingh$. The following two facts are established: 1) $\ingh$ has no globally hyperbolic maximal extension. This means that by shaping appropriately a precompact portion of a globally hyperbolic region one can \emph{force} the Universe to produce either a closed causal curve, or a quasiregular singularity, whichever it abhors less; 2) Before a CDCH is formed a null geodesic appears which infinitely approaches the horizon returning again and again in the same --- arbitrarily small --- region. The energy of the photon moving on such a geodesic increases with each passage, or at least falls insufficiently fast. As a result, an observer located in the mentioned region would see a bunch of photons passing through his laboratory with the arbitrarily large total energy. We speculate that this phenomenon may have observable consequences.
[ { "created": "Fri, 9 May 2014 16:14:46 GMT", "version": "v1" }, { "created": "Fri, 1 Aug 2014 10:15:05 GMT", "version": "v2" } ]
2015-06-19
[ [ "Krasnikov", "S.", "" ] ]
The building of a time machine, if possible at all, requires the relevant regions of spacetime to be compact (that is, physically speaking, free from sources of unpredictability such as infinities and singularities). Motivated by this argument we consider the spacetimes with the compactly determined Cauchy horizons (CDCHs), the defining property of which is the compactness of $\overline{J^-(\EuScript U)}\cap J^+(\EuScript S_0)$, where $\EuScript U$ is an open subset of the Cauchy horizon and $\EuScript S_0$ is a Cauchy surface of the initial globally hyperbolic region $\ingh$. The following two facts are established: 1) $\ingh$ has no globally hyperbolic maximal extension. This means that by shaping appropriately a precompact portion of a globally hyperbolic region one can \emph{force} the Universe to produce either a closed causal curve, or a quasiregular singularity, whichever it abhors less; 2) Before a CDCH is formed a null geodesic appears which infinitely approaches the horizon returning again and again in the same --- arbitrarily small --- region. The energy of the photon moving on such a geodesic increases with each passage, or at least falls insufficiently fast. As a result, an observer located in the mentioned region would see a bunch of photons passing through his laboratory with the arbitrarily large total energy. We speculate that this phenomenon may have observable consequences.
gr-qc/9910065
Claus Kiefer
C. Kiefer, D. Polarski, A.A. Starobinsky
Entropy of gravitons produced in the early Universe
8 pages, REVTEX, final version to match the version to be published in Phys. Rev. D; minor additions in the Introduction, results unchanged
Phys.Rev. D62 (2000) 043518
10.1103/PhysRevD.62.043518
Freiburg THEP-99/5
gr-qc astro-ph hep-th quant-ph
null
Gravitons produced from quantum vacuum fluctuations during an inflationary stage in the early Universe have zero entropy as far as they reflect the time evolution (squeezing) of a pure state, their large occupation number notwithstanding. A non-zero entropy of the gravitons (classical gravitational waves (GW) after decoherence) can be obtained through coarse graining. The latter has to be physically justified {\it and} should not contradict observational constraints. We propose two ways of coarse graining for which the fixed temporal phase of each Fourier mode of the GW background still remains observable: one based on quantum entanglement, and another one following from the presence of a secondary GW background. The proposals are shown to be mutually consistent. They lead to the result that the entropy of the primordial GW background is significantly smaller than it was thought earlier. The difference can be ascribed to the information about the regular (inflationary) initial state of the Universe which is stored in this background and which reveals itself, in particular, in the appearance of primordial peaks (acoustic peaks in the case of scalar perturbations) in the multipole spectra of the CMB temperature anisotropy and polarization.
[ { "created": "Wed, 20 Oct 1999 07:43:47 GMT", "version": "v1" }, { "created": "Sat, 8 Apr 2000 11:02:43 GMT", "version": "v2" } ]
2009-10-31
[ [ "Kiefer", "C.", "" ], [ "Polarski", "D.", "" ], [ "Starobinsky", "A. A.", "" ] ]
Gravitons produced from quantum vacuum fluctuations during an inflationary stage in the early Universe have zero entropy as far as they reflect the time evolution (squeezing) of a pure state, their large occupation number notwithstanding. A non-zero entropy of the gravitons (classical gravitational waves (GW) after decoherence) can be obtained through coarse graining. The latter has to be physically justified {\it and} should not contradict observational constraints. We propose two ways of coarse graining for which the fixed temporal phase of each Fourier mode of the GW background still remains observable: one based on quantum entanglement, and another one following from the presence of a secondary GW background. The proposals are shown to be mutually consistent. They lead to the result that the entropy of the primordial GW background is significantly smaller than it was thought earlier. The difference can be ascribed to the information about the regular (inflationary) initial state of the Universe which is stored in this background and which reveals itself, in particular, in the appearance of primordial peaks (acoustic peaks in the case of scalar perturbations) in the multipole spectra of the CMB temperature anisotropy and polarization.
1207.1646
Mahouton J. Stephane Houndjo Dr
M. J. S. Houndjo, F. G. Alvarenga, Manuel E. Rodrigues, Deborah F. Jardim and R. Myrzakulov
Thermodynamics in Little Rip cosmology in the framework of a type of f(R,T) gravity
18 pages
Eur. Phys. J. Plus (2014) 129: 171
null
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Cosmological reconstruction of Little Rip model in $f(R, T)$ gravity is investigated, where $R$ is the curvature scalar and $T$ the trace of the energy momentum tensor. The model perfectly reproduces the present stage of the universe, characterized by the $\Lambda CDM$ model, without singularity at future finite-time (without the Big Rip). The input parameters are determined according to Supernovae Cosmology data and perfectly fit with the WMAP around the Little Rip. Moreover, the thermodynamics is considered in this Little Rip cosmology and it is illustrated that the second law of thermodynamics is always satisfied around the Little Rip universe for the temperature inside the horizon being the same as that of the apparent horizon. Moreover, we show the existence of a stable fixed point in the Little Rip universe which confirms that this is actually a late-time attractor in the phantom-dominated universe. The linear perturbation analysis is performed around the critical points, showing that the Little Rip model obtained is stable.
[ { "created": "Thu, 5 Jul 2012 19:35:35 GMT", "version": "v1" }, { "created": "Sat, 15 Dec 2012 00:21:00 GMT", "version": "v2" } ]
2014-09-05
[ [ "Houndjo", "M. J. S.", "" ], [ "Alvarenga", "F. G.", "" ], [ "Rodrigues", "Manuel E.", "" ], [ "Jardim", "Deborah F.", "" ], [ "Myrzakulov", "R.", "" ] ]
Cosmological reconstruction of Little Rip model in $f(R, T)$ gravity is investigated, where $R$ is the curvature scalar and $T$ the trace of the energy momentum tensor. The model perfectly reproduces the present stage of the universe, characterized by the $\Lambda CDM$ model, without singularity at future finite-time (without the Big Rip). The input parameters are determined according to Supernovae Cosmology data and perfectly fit with the WMAP around the Little Rip. Moreover, the thermodynamics is considered in this Little Rip cosmology and it is illustrated that the second law of thermodynamics is always satisfied around the Little Rip universe for the temperature inside the horizon being the same as that of the apparent horizon. Moreover, we show the existence of a stable fixed point in the Little Rip universe which confirms that this is actually a late-time attractor in the phantom-dominated universe. The linear perturbation analysis is performed around the critical points, showing that the Little Rip model obtained is stable.
2401.14251
Istvan Racz
Istv\'an R\'acz
On quasi-local angular momentum and the construction of axial vector fields
The suggested angular momentum expression is gauge-dependent
null
null
null
gr-qc
http://creativecommons.org/licenses/by/4.0/
A method is introduced which, for the first time, allows us to construct axial vector fields without which formal definitions of quasi-local angular momentum, in general, would remain empty. The introduced method is practical, it can be used to construct all such axial vector fields, and it allows the quasi-local angular momentum to be represented by a triple vector in three-dimensional Euclidean space. We also derive balance relations which allow us to monitor the variation of the magnitude and direction of this vector, and also to monitor the angular momentum transports in generic spacetimes without symmetries.
[ { "created": "Thu, 25 Jan 2024 15:41:29 GMT", "version": "v1" }, { "created": "Thu, 8 Feb 2024 08:12:32 GMT", "version": "v2" } ]
2024-02-09
[ [ "Rácz", "István", "" ] ]
A method is introduced which, for the first time, allows us to construct axial vector fields without which formal definitions of quasi-local angular momentum, in general, would remain empty. The introduced method is practical, it can be used to construct all such axial vector fields, and it allows the quasi-local angular momentum to be represented by a triple vector in three-dimensional Euclidean space. We also derive balance relations which allow us to monitor the variation of the magnitude and direction of this vector, and also to monitor the angular momentum transports in generic spacetimes without symmetries.
1805.05889
Poonam Agrawal Dr
D. D. Pawar, G. G. Bhuttampalle and P. K. Agrawal
Kaluza-Klein String Cosmological Model in f(R; T) Theory of Gravity
Accepted for publication in New Astronomy, May 2018
null
10.1016/j.newast.2018.05.002
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper we have studied Kaluza-Klein string cosmological model within the framework of f(R; T) theory of gravity, where R is the Ricci scalar and T is the trace of the stress energy momentum tensor. We have obtained the solution of the corresponding field equations by using a time varying deceleration parameter. We also discussed various physical and dynamical properties of the model. The variation of different cosmological parameters are shown graphically for specific values of the parameters of the model.
[ { "created": "Tue, 15 May 2018 16:23:23 GMT", "version": "v1" } ]
2018-06-06
[ [ "Pawar", "D. D.", "" ], [ "Bhuttampalle", "G. G.", "" ], [ "Agrawal", "P. K.", "" ] ]
In this paper we have studied Kaluza-Klein string cosmological model within the framework of f(R; T) theory of gravity, where R is the Ricci scalar and T is the trace of the stress energy momentum tensor. We have obtained the solution of the corresponding field equations by using a time varying deceleration parameter. We also discussed various physical and dynamical properties of the model. The variation of different cosmological parameters are shown graphically for specific values of the parameters of the model.
2012.00047
Ismael Ayuso
Ismael Ayuso, Francisco S. N. Lobo and Jos\'e P. Mimoso
Wormhole geometries induced by action-dependent Lagrangian theories
11 pages, 5 figures, V2: version accepted for publication in PRD
Phys. Rev. D 103, 044018 (2021)
10.1103/PhysRevD.103.044018
null
gr-qc astro-ph.HE hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this work, we explore wormhole geometries in a recently proposed modified gravity theory arising from a non-conservative gravitational theory, tentatively denoted action-dependent Lagrangian theories. The generalized gravitational field equation essentially depends on a background four-vector $\lambda^\mu$, that plays the role of a coupling parameter associated with the dependence of the gravitational Lagrangian upon the action, and may generically depend on the spacetime coordinates. Considering wormhole configurations, by using "Buchdahl coordinates", we find that the four-vector is given by $\lambda_{\mu}=\left(0,0,\lambda_{\theta},0\right)$, and that the spacetime geometry is severely restricted by the condition $g_{tt}g_{uu}=-1$, where $u$ is the radial coordinate. We find a plethora of specific asymptotically flat, symmetric and asymmetric, solutions with power law choices for the function $\lambda$, by generalizing the Ellis-Bronnikov solutions and the recently proposed black bounce geometries, amongst others. We show that these compact objects possess a far richer geometrical structure than their general relativistic counterparts.
[ { "created": "Mon, 30 Nov 2020 19:01:31 GMT", "version": "v1" }, { "created": "Tue, 26 Jan 2021 11:34:57 GMT", "version": "v2" } ]
2021-02-12
[ [ "Ayuso", "Ismael", "" ], [ "Lobo", "Francisco S. N.", "" ], [ "Mimoso", "José P.", "" ] ]
In this work, we explore wormhole geometries in a recently proposed modified gravity theory arising from a non-conservative gravitational theory, tentatively denoted action-dependent Lagrangian theories. The generalized gravitational field equation essentially depends on a background four-vector $\lambda^\mu$, that plays the role of a coupling parameter associated with the dependence of the gravitational Lagrangian upon the action, and may generically depend on the spacetime coordinates. Considering wormhole configurations, by using "Buchdahl coordinates", we find that the four-vector is given by $\lambda_{\mu}=\left(0,0,\lambda_{\theta},0\right)$, and that the spacetime geometry is severely restricted by the condition $g_{tt}g_{uu}=-1$, where $u$ is the radial coordinate. We find a plethora of specific asymptotically flat, symmetric and asymmetric, solutions with power law choices for the function $\lambda$, by generalizing the Ellis-Bronnikov solutions and the recently proposed black bounce geometries, amongst others. We show that these compact objects possess a far richer geometrical structure than their general relativistic counterparts.
gr-qc/0307019
Jose Wadih Maluf
J. W. Maluf, F. F. Faria and K. H. Castello-Branco
The gravitational energy-momentum flux
20 pages, latex file, no figures, two references added, accepted for publication in Class. Quantum Gravity
Class.Quant.Grav. 20 (2003) 4683-4694
10.1088/0264-9381/20/21/008
null
gr-qc
null
We present a continuity equation for the gravitational energy-momentum, which is obtained in the framework of the teleparallel equivalent of general relativity. From this equation it follows a general definition for the gravitational energy-momentum flux. This definition is investigated in the context of plane waves and of cylindrical Einstein-Rosen waves. We obtain the well known value for the energy flux of plane gravitational waves, and conclude that the latter exhibit features similar to plane electromagnetic waves.
[ { "created": "Fri, 4 Jul 2003 11:16:25 GMT", "version": "v1" }, { "created": "Tue, 26 Aug 2003 13:17:21 GMT", "version": "v2" } ]
2009-11-10
[ [ "Maluf", "J. W.", "" ], [ "Faria", "F. F.", "" ], [ "Castello-Branco", "K. H.", "" ] ]
We present a continuity equation for the gravitational energy-momentum, which is obtained in the framework of the teleparallel equivalent of general relativity. From this equation it follows a general definition for the gravitational energy-momentum flux. This definition is investigated in the context of plane waves and of cylindrical Einstein-Rosen waves. We obtain the well known value for the energy flux of plane gravitational waves, and conclude that the latter exhibit features similar to plane electromagnetic waves.
1608.01940
LVC Publications
The LIGO Scientific Collaboration and the Virgo Collaboration: B. P. Abbott, R. Abbott, T. D. Abbott, M. R. Abernathy, F. Acernese, K. Ackley, C. Adams, T. Adams, P. Addesso, R. X. Adhikari, V. B. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, B. Allen, A. Allocca, P. A. Altin, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, C. C. Arceneaux, J. S. Areeda, N. Arnaud, K. G. Arun, S. Ascenzi, G. Ashton, M. Ast, S. M. Aston, P. Astone, P. Aufmuth, C. Aulbert, S. Babak, P. Bacon, M. K. M. Bader, F. Baldaccini, G. Ballardin, S. W. Ballmer, J. C. Barayoga, S. E. Barclay, B. C. Barish, D. Barker, F. Barone, B. Barr, L. Barsotti, M. Barsuglia, D. Barta, J. Bartlett, I. Bartos, R. Bassiri, A. Basti, J. C. Batch, C. Baune, V. Bavigadda, M. Bazzan, M. Bejger, A. S. Bell, G. Bergmann, C. P. L. Berry, D. Bersanetti, A. Bertolini, J. Betzwieser, S. Bhagwat, R. Bhandare, I. A. Bilenko, G. Billingsley, J. Birch, R. Birney, O. Birnholtz, S. Biscans, A. Bisht, M. Bitossi, C. Biwer, M. A. Bizouard, J. K. Blackburn, C. D. Blair, D. G. Blair, R. M. Blair, S. Bloemen, O. Bock, M. Boer, G. Bogaert, C. Bogan, A. Bohe, C. Bond, F. Bondu, R. Bonnand, B. A. Boom, R. Bork, V. Boschi, S. Bose, Y. Bouffanais, A. Bozzi, C. Bradaschia, V. B. Braginsky, M. Branchesi, J. E. Brau, T. Briant, A. Brillet, M. Brinkmann, V. Brisson, P. Brockill, J. E. Broida, A. F. Brooks, D. A. Brown, D. D. Brown, N. M. Brown, S. Brunett, C. C. Buchanan, A. Buikema, T. Bulik, H. J. Bulten, A. Buonanno, D. Buskulic, C. Buy, R. L. Byer, M. Cabero, L. Cadonati, G. Cagnoli, C. Cahillane, J. Calder\'on Bustillo, T. Callister, E. Calloni, J. B. Camp, K. C. Cannon, J. Cao, C. D. Capano, E. Capocasa, F. Carbognani, S. Caride, J. Casanueva Diaz, C. Casentini, S. Caudill, M. Cavagli\`a, F. Cavalier, R. Cavalieri, G. Cella, C. B. Cepeda, L. Cerboni Baiardi, G. Cerretani, E. Cesarini, S. J. Chamberlin, M. Chan, S. Chao, P. Charlton, E. Chassande-Mottin, H. Y. Chen, Y. Chen, C. Cheng, A. Chincarini, A. Chiummo, H. S. Cho, M. Cho, J. H. Chow, N. Christensen, Q. Chu, S. Chua, S. Chung, G. Ciani, F. Clara, J. A. Clark, F. Cleva, E. Coccia, P.-F. Cohadon, A. Colla, C. G. Collette, L. Cominsky, M. Constancio Jr, A. Conte, L. Conti, D. Cook, T. R. Corbitt, A. Corsi, S. Cortese, C. A. Costa, M. W. Coughlin, S. B. Coughlin, J.-P. Coulon, S. T. Countryman, P. Couvares, E. E. Cowan, D. M. Coward, M. J. Cowart, D. C. Coyne, R. Coyne, K. Craig, J. D. E. Creighton, J. Cripe, S. G. Crowder, A. Cumming, L. Cunningham, E. Cuoco, T. Dal Canton, S. L. Danilishin, S. D'Antonio, K. Danzmann, N. S. Darman, A. Dasgupta, C. F. Da Silva Costa, V. Dattilo, I. Dave, M. Davier, G. S. Davies, E. J. Daw, R. Day, S. De, D. DeBra, G. Debreczeni, J. Degallaix, M. De Laurentis, S. Del\'eglise, W. Del Pozzo, T. Denker, T. Dent, V. Dergachev, R. De Rosa, R. T. DeRosa, R. DeSalvo, R. C. Devine, S. Dhurandhar, M. C. D\'iaz, L. Di Fiore, M. Di Giovanni, T. Di Girolamo, A. Di Lieto, S. Di Pace, I. Di Palma, A. Di Virgilio, V. Dolique, F. Donovan, K. L. Dooley, S. Doravari, R. Douglas, T. P. Downes, M. Drago, R. W. P. Drever, J. C. Driggers, M. Ducrot, S. E. Dwyer, T. B. Edo, M. C. Edwards, A. Effler, H.-B. Eggenstein, P. Ehrens, J. Eichholz, S. S. Eikenberry, W. Engels, R. C. Essick, T. Etzel, M. Evans, T. M. Evans, R. Everett, M. Factourovich, V. Fafone, H. Fair, S. Fairhurst, X. Fan, Q. Fang, S. Farinon, B. Farr, W. M. Farr, M. Favata, M. Fays, H. Fehrmann, M. M. Fejer, E. Fenyvesi, I. Ferrante, E. C. Ferreira, F. Ferrini, F. Fidecaro, I. Fiori, D. Fiorucci, R. P. Fisher, R. Flaminio, M. Fletcher, J.-D. Fournier, S. Frasca, F. Frasconi, Z. Frei, A. Freise, R. Frey, V. Frey, P. Fritschel, V. V. Frolov, P. Fulda, M. Fyffe, H. A. G. Gabbard, J. R. Gair, L. Gammaitoni, S. G. Gaonkar, F. Garufi, G. Gaur, N. Gehrels, G. Gemme, P. Geng, E. Genin, A. Gennai, J. George, L. Gergely, V. Germain, Abhirup Ghosh, Archisman Ghosh, S. Ghosh, J. A. Giaime, K. D. Giardina, A. Giazotto, K. Gill, A. Glaefke, E. Goetz, R. Goetz, L. Gondan, G. Gonz\'alez, J. M. Gonzalez Castro, A. Gopakumar, N. A. Gordon, M. L. Gorodetsky, S. E. Gossan, M. Gosselin, R. Gouaty, A. Grado, C. Graef, P. B. Graff, M. Granata, A. Grant, S. Gras, C. Gray, G. Greco, A. C. Green, P. Groot, H. Grote, S. Grunewald, G. M. Guidi, X. Guo, A. Gupta, M. K. Gupta, K. E. Gushwa, E. K. Gustafson, R. Gustafson, J. J. Hacker, B. R. Hall, E. D. Hall, G. Hammond, M. Haney, M. M. Hanke, J. Hanks, C. Hanna, M. D. Hannam, J. Hanson, T. Hardwick, J. Harms, G. M. Harry, I. W. Harry, M. J. Hart, M. T. Hartman, C.-J. Haster, K. Haughian, A. Heidmann, M. C. Heintze, H. Heitmann, P. Hello, G. Hemming, M. Hendry, I. S. Heng, J. Hennig, J. Henry, A. W. Heptonstall, M. Heurs, S. Hild, D. Hoak, D. Hofman, K. Holt, D. E. Holz, P. Hopkins, J. Hough, E. A. Houston, E. J. Howell, Y. M. Hu, S. Huang, E. A. Huerta, D. Huet, B. Hughey, S. Husa, S. H. Huttner, T. Huynh-Dinh, N. Indik, D. R. Ingram, R. Inta, H. N. Isa, J.-M. Isac, M. Isi, T. Isogai, B. R. Iyer, K. Izumi, T. Jacqmin, H. Jang, K. Jani, P. Jaranowski, S. Jawahar, L. Jian, F. Jim\'enez-Forteza, W. W. Johnson, D. I. Jones, R. Jones, R. J. G. Jonker, L. Ju, Haris K, C. V. Kalaghatgi, V. Kalogera, S. Kandhasamy, G. Kang, J. B. Kanner, S. J. Kapadia, S. Karki, K. S. Karvinen, M. Kasprzack, E. Katsavounidis, W. Katzman, S. Kaufer, T. Kaur, K. Kawabe, F. K\'ef\'elian, M. S. Kehl, D. Keitel, D. B. Kelley, W. Kells, R. Kennedy, J. S. Key, F. Y. Khalili, I. Khan, S. Khan, Z. Khan, E. A. Khazanov, N. Kijbunchoo, Chi-Woong Kim, Chunglee Kim, J. Kim, K. Kim, N. Kim, W. Kim, Y.-M. Kim, S. J. Kimbrell, E. J. King, P. J. King, J. S. Kissel, B. Klein, L. Kleybolte, S. Klimenko, S. M. Koehlenbeck, S. Koley, V. Kondrashov, A. Kontos, M. Korobko, W. Z. Korth, I. Kowalska, D. B. Kozak, V. Kringel, B. Krishnan, A. Kr\'olak, C. Krueger, G. Kuehn, P. Kumar, R. Kumar, L. Kuo, A. Kutynia, B. D. Lackey, M. Landry, J. Lange, B. Lantz, P. D. Lasky, M. Laxen, A. Lazzarini, C. Lazzaro, P. Leaci, S. Leavey, E. O. Lebigot, C. H. Lee, H. K. Lee, H. M. Lee, K. Lee, A. Lenon, M. Leonardi, J. R. Leong, N. Leroy, N. Letendre, Y. Levin, J. B. Lewis, T. G. F. Li, A. Libson, T. B. Littenberg, N. A. Lockerbie, A. L. Lombardi, L. T. London, J. E. Lord, M. Lorenzini, V. Loriette, M. Lormand, G. Losurdo, J. D. Lough, H. L\"uck, A. P. Lundgren, R. Lynch, Y. Ma, B. Machenschalk, M. MacInnis, D. M. Macleod, F. Maga\~na-Sandoval, L. Magana Zertuche, R. M. Magee, E. Majorana, I. Maksimovic, V. Malvezzi, N. Man, V. Mandic, V. Mangano, G. L. Mansell, M. Manske, M. Mantovani, F. Marchesoni, F. Marion, S. M\'arka, Z. M\'arka, A. S. Markosyan, E. Maros, F. Martelli, L. Martellini, I. W. Martin, D. V. Martynov, J. N. Marx, K. Mason, A. Masserot, T. J. Massinger, M. Masso-Reid, S. Mastrogiovanni, F. Matichard, L. Matone, N. Mavalvala, N. Mazumder, R. McCarthy, D. E. McClelland, S. McCormick, S. C. McGuire, G. McIntyre, J. McIver, D. J. McManus, T. McRae, D. Meacher, G. D. Meadors, J. Meidam, A. Melatos, G. Mendell, R. A. Mercer, E. L. Merilh, M. Merzougui, S. Meshkov, C. Messenger, C. Messick, R. Metzdorff, P. M. Meyers, F. Mezzani, H. Miao, C. Michel, H. Middleton, E. E. Mikhailov, L. Milano, A. L. Miller, A. Miller, B. B. Miller, J. Miller, M. Millhouse, Y. Minenkov, J. Ming, S. Mirshekari, C. Mishra, S. Mitra, V. P. Mitrofanov, G. Mitselmakher, R. Mittleman, A. Moggi, M. Mohan, S. R. P. Mohapatra, M. Montani, B. C. Moore, C. J. Moore, D. Moraru, G. Moreno, S. R. Morriss, K. Mossavi, B. Mours, C. M. Mow-Lowry, G. Mueller, A. W. Muir, Arunava Mukherjee, D. Mukherjee, S. Mukherjee, N. Mukund, A. Mullavey, J. Munch, D. J. Murphy, P. G. Murray, A. Mytidis, I. Nardecchia, L. Naticchioni, R. K. Nayak, K. Nedkova, G. Nelemans, T. J. N. Nelson, M. Neri, A. Neunzert, G. Newton, T. T. Nguyen, A. B. Nielsen, S. Nissanke, A. Nitz, F. Nocera, D. Nolting, M. E. N. Normandin, L. K. Nuttall, J. Oberling, E. Ochsner, J. O'Dell, E. Oelker, G. H. Ogin, J. J. Oh, S. H. Oh, F. Ohme, M. Oliver, P. Oppermann, Richard J. Oram, B. O'Reilly, R. O'Shaughnessy, D. J. Ottaway, H. Overmier, B. J. Owen, A. Pai, S. A. Pai, J. R. Palamos, O. Palashov, C. Palomba, A. Pal-Singh, H. Pan, C. Pankow, F. Pannarale, B. C. Pant, F. Paoletti, A. Paoli, M. A. Papa, H. R. Paris, W. Parker, D. Pascucci, A. Pasqualetti, R. Passaquieti, D. Passuello, B. Patricelli, Z. Patrick, B. L. Pearlstone, M. Pedraza, R. Pedurand, L. Pekowsky, A. Pele, S. Penn, A. Perreca, L. M. Perri, M. Phelps, O. J. Piccinni, M. Pichot, F. Piergiovanni, V. Pierro, G. Pillant, L. Pinard, I. M. Pinto, M. Pitkin, M. Poe, R. Poggiani, P. Popolizio, A. Post, J. Powell, J. Prasad, J. Pratt, V. Predoi, T. Prestegard, L. R. Price, M. Prijatelj, M. Principe, S. Privitera, R. Prix, G. A. Prodi, L. Prokhorov, O. Puncken, M. Punturo, P. Puppo, M. P"urrer, H. Qi, J. Qin, S. Qiu, V. Quetschke, E. A. Quintero, R. Quitzow-James, F. J. Raab, D. S. Rabeling, H. Radkins, P. Raffai, S. Raja, C. Rajan, M. Rakhmanov, P. Rapagnani, V. Raymond, M. Razzano, V. Re, J. Read, C. M. Reed, T. Regimbau, L. Rei, S. Reid, H. Rew, S. D. Reyes, F. Ricci, K. Riles, M. Rizzo, N. A. Robertson, R. Robie, F. Robinet, A. Rocchi, L. Rolland, J. G. Rollins, V. J. Roma, J. D. Romano, R. Romano, G. Romanov, J. H. Romie, D. Rosi\'nska, S. Rowan, A. R\"udiger, P. Ruggi, K. Ryan, S. Sachdev, T. Sadecki, L. Sadeghian, M. Sakellariadou, L. Salconi, M. Saleem, F. Salemi, A. Samajdar, L. Sammut, E. J. Sanchez, V. Sandberg, B. Sandeen, J. R. Sanders, B. Sassolas, P. R. Saulson, O. E. S. Sauter, R. L. Savage, A. Sawadsky, P. Schale, R. Schilling, J. Schmidt, P. Schmidt, R. Schnabel, R. M. S. Schofield, A. Sch\"onbeck, E. Schreiber, D. Schuette, B. F. Schutz, J. Scott, S. M. Scott, D. Sellers, A. S. Sengupta, D. Sentenac, V. Sequino, A. Sergeev, Y. Setyawati, D. A. Shaddock, T. Shaffer, M. S. Shahriar, M. Shaltev, B. Shapiro, A. Sheperd, D. H. Shoemaker, D. M. Shoemaker, K. Siellez, X. Siemens, M. Sieniawska, D. Sigg, A. D. Silva, A. Singer, L. P. Singer, A. Singh, R. Singh, A. Singhal, A. M. Sintes, B. J. J. Slagmolen, J. R. Smith, N. D. Smith, R. J. E. Smith, E. J. Son, B. Sorazu, F. Sorrentino, T. Souradeep, A. K. Srivastava, A. Staley, M. Steinke, J. Steinlechner, S. Steinlechner, D. Steinmeyer, B. C. Stephens, R. Stone, K. A. Strain, N. Straniero, G. Stratta, N. A. Strauss, S. Strigin, R. Sturani, A. L. Stuver, T. Z. Summerscales, L. Sun, S. Sunil, P. J. Sutton, B. L. Swinkels, M. J. Szczepa\'nczyk, M. Tacca, D. Talukder, D. B. Tanner, M. T\'apai, S. P. Tarabrin, A. Taracchini, R. Taylor, T. Theeg, M. P. Thirugnanasambandam, E. G. Thomas, M. Thomas, P. Thomas, K. A. Thorne, K. S. Thorne, E. Thrane, S. Tiwari, V. Tiwari, K. V. Tokmakov, K. Toland, C. Tomlinson, M. Tonelli, Z. Tornasi, C. V. Torres, C. I. Torrie, D. T\"oyr\"a, F. Travasso, G. Traylor, D. Trifir\`o, M. C. Tringali, L. Trozzo, M. Tse, M. Turconi, D. Tuyenbayev, D. Ugolini, C. S. Unnikrishnan, A. L. Urban, S. A. Usman, H. Vahlbruch, G. Vajente, G. Valdes, N. van Bakel, M. van Beuzekom, J. F. J. van den Brand, C. Van Den Broeck, D. C. Vander-Hyde, L. van der Schaaf, J. V. van Heijningen, A. A. van Veggel, M. Vardaro, S. Vass, M. Vas\'uth, R. Vaulin, A. Vecchio, G. Vedovato, J. Veitch, P. J. Veitch, K. Venkateswara, D. Verkindt, F. Vetrano, A. Vicer\'e, S. Vinciguerra, D. J. Vine, J.-Y. Vinet, S. Vitale, T. Vo, H. Vocca, C. Vorvick, D. V. Voss, W. D. Vousden, S. P. Vyatchanin, A. R. Wade, L. E. Wade, M. Wade, M. Walker, L. Wallace, S. Walsh, G. Wang, H. Wang, M. Wang, X. Wang, Y. Wang, R. L. Ward, J. Warner, M. Was, B. Weaver, L.-W. Wei, M. Weinert, A. J. Weinstein, R. Weiss, L. Wen, P. Wessels, T. Westphal, K. Wette, J. T. Whelan, B. F. Whiting, R. D. Williams, A. R. Williamson, J. L. Willis, B. Willke, M. H. Wimmer, W. Winkler, C. C. Wipf, A. G. Wiseman, H. Wittel, G. Woan, J. Woehler, J. Worden, J. L. Wright, D. S. Wu, G. Wu, J. Yablon, W. Yam, H. Yamamoto, C. C. Yancey, H. Yu, M. Yvert, A. Zadro.zny, L. Zangrando, M. Zanolin, J.-P. Zendri, M. Zevin, L. Zhang, M. Zhang, Y. Zhang, C. Zhao, M. Zhou, Z. Zhou, X. J. Zhu, M. E. Zucker, S. E. Zuraw, J. Zweizig
The basic physics of the binary black hole merger GW150914
updated to match published version
LIGO Scientific and Virgo Collaborations, Annalen der Physik, Volume 529, Issue 1-2, January 2017, 1600209
10.1002/andp.201600209
null
gr-qc
http://creativecommons.org/licenses/by/4.0/
The first direct gravitational-wave detection was made by the Advanced Laser Interferometer Gravitational Wave Observatory on September 14, 2015. The GW150914 signal was strong enough to be apparent, without using any waveform model, in the filtered detector strain data. Here, features of the signal visible in the data are analyzed using concepts from Newtonian physics and general relativity, accessible to anyone with a general physics background. The simple analysis presented here is consistent with the fully general-relativistic analyses published elsewhere,in showing that the signal was produced by the inspiral and subsequent merger of two black holes. The black holes were each of approximately 35 Msun, still orbited each other as close as ~350 km apart, and subsequently merged to form a single black hole. Similar reasoning, directly from the data, is used to roughly estimate how far these black holes were from the Earth, and the energy that they radiated in gravitational waves.
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2017-02-27
[ [ "The LIGO Scientific Collaboration", "", "" ], [ "the Virgo Collaboration", "", "" ], [ "Abbott", "B. P.", "" ], [ "Abbott", "R.", "" ], [ "Abbott", "T. D.", "" ], [ "Abernathy", "M. R.", "" ], [ "Acernese", "F.", "" ], [ "Ackley", "K.", "" ], [ "Adams", "C.", "" ], [ "Adams", "T.", "" ], [ "Addesso", "P.", "" ], [ "Adhikari", "R. X.", "" ], [ "Adya", "V. B.", "" ], [ "Affeldt", "C.", "" ], [ "Agathos", "M.", "" ], [ "Agatsuma", "K.", "" ], [ "Aggarwal", "N.", "" ], [ "Aguiar", "O. D.", "" ], [ "Aiello", "L.", "" ], [ "Ain", "A.", "" ], [ "Ajith", "P.", "" ], [ "Allen", "B.", "" ], [ "Allocca", "A.", "" ], [ "Altin", "P. A.", "" ], [ "Anderson", "S. B.", "" ], [ "Anderson", "W. G.", "" ], [ "Arai", "K.", "" ], [ "Araya", "M. C.", "" ], [ "Arceneaux", "C. C.", "" ], [ "Areeda", "J. S.", "" ], [ "Arnaud", "N.", "" ], [ "Arun", "K. G.", "" ], [ "Ascenzi", "S.", "" ], [ "Ashton", "G.", "" ], [ "Ast", "M.", "" ], [ "Aston", "S. 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R.", "" ], [ "Sauter", "O. E. S.", "" ], [ "Savage", "R. L.", "" ], [ "Sawadsky", "A.", "" ], [ "Schale", "P.", "" ], [ "Schilling", "R.", "" ], [ "Schmidt", "J.", "" ], [ "Schmidt", "P.", "" ], [ "Schnabel", "R.", "" ], [ "Schofield", "R. M. S.", "" ], [ "Schönbeck", "A.", "" ], [ "Schreiber", "E.", "" ], [ "Schuette", "D.", "" ], [ "Schutz", "B. F.", "" ], [ "Scott", "J.", "" ], [ "Scott", "S. M.", "" ], [ "Sellers", "D.", "" ], [ "Sengupta", "A. S.", "" ], [ "Sentenac", "D.", "" ], [ "Sequino", "V.", "" ], [ "Sergeev", "A.", "" ], [ "Setyawati", "Y.", "" ], [ "Shaddock", "D. A.", "" ], [ "Shaffer", "T.", "" ], [ "Shahriar", "M. S.", "" ], [ "Shaltev", "M.", "" ], [ "Shapiro", "B.", "" ], [ "Sheperd", "A.", "" ], [ "Shoemaker", "D. H.", "" ], [ "Shoemaker", "D. M.", "" ], [ "Siellez", "K.", "" ], [ "Siemens", "X.", "" ], [ "Sieniawska", "M.", "" ], [ "Sigg", "D.", "" ], [ "Silva", "A. D.", "" ], [ "Singer", "A.", "" ], [ "Singer", "L. P.", "" ], [ "Singh", "A.", "" ], [ "Singh", "R.", "" ], [ "Singhal", "A.", "" ], [ "Sintes", "A. M.", "" ], [ "Slagmolen", "B. J. J.", "" ], [ "Smith", "J. R.", "" ], [ "Smith", "N. D.", "" ], [ "Smith", "R. J. E.", "" ], [ "Son", "E. J.", "" ], [ "Sorazu", "B.", "" ], [ "Sorrentino", "F.", "" ], [ "Souradeep", "T.", "" ], [ "Srivastava", "A. K.", "" ], [ "Staley", "A.", "" ], [ "Steinke", "M.", "" ], [ "Steinlechner", "J.", "" ], [ "Steinlechner", "S.", "" ], [ "Steinmeyer", "D.", "" ], [ "Stephens", "B. C.", "" ], [ "Stone", "R.", "" ], [ "Strain", "K. A.", "" ], [ "Straniero", "N.", "" ], [ "Stratta", "G.", "" ], [ "Strauss", "N. A.", "" ], [ "Strigin", "S.", "" ], [ "Sturani", "R.", "" ], [ "Stuver", "A. L.", "" ], [ "Summerscales", "T. Z.", "" ], [ "Sun", "L.", "" ], [ "Sunil", "S.", "" ], [ "Sutton", "P. J.", "" ], [ "Swinkels", "B. L.", "" ], [ "Szczepańczyk", "M. J.", "" ], [ "Tacca", "M.", "" ], [ "Talukder", "D.", "" ], [ "Tanner", "D. B.", "" ], [ "Tápai", "M.", "" ], [ "Tarabrin", "S. P.", "" ], [ "Taracchini", "A.", "" ], [ "Taylor", "R.", "" ], [ "Theeg", "T.", "" ], [ "Thirugnanasambandam", "M. P.", "" ], [ "Thomas", "E. G.", "" ], [ "Thomas", "M.", "" ], [ "Thomas", "P.", "" ], [ "Thorne", "K. A.", "" ], [ "Thorne", "K. S.", "" ], [ "Thrane", "E.", "" ], [ "Tiwari", "S.", "" ], [ "Tiwari", "V.", "" ], [ "Tokmakov", "K. V.", "" ], [ "Toland", "K.", "" ], [ "Tomlinson", "C.", "" ], [ "Tonelli", "M.", "" ], [ "Tornasi", "Z.", "" ], [ "Torres", "C. V.", "" ], [ "Torrie", "C. I.", "" ], [ "Töyrä", "D.", "" ], [ "Travasso", "F.", "" ], [ "Traylor", "G.", "" ], [ "Trifirò", "D.", "" ], [ "Tringali", "M. C.", "" ], [ "Trozzo", "L.", "" ], [ "Tse", "M.", "" ], [ "Turconi", "M.", "" ], [ "Tuyenbayev", "D.", "" ], [ "Ugolini", "D.", "" ], [ "Unnikrishnan", "C. S.", "" ], [ "Urban", "A. L.", "" ], [ "Usman", "S. A.", "" ], [ "Vahlbruch", "H.", "" ], [ "Vajente", "G.", "" ], [ "Valdes", "G.", "" ], [ "van Bakel", "N.", "" ], [ "van Beuzekom", "M.", "" ], [ "Brand", "J. F. J. van den", "" ], [ "Broeck", "C. Van Den", "" ], [ "Vander-Hyde", "D. C.", "" ], [ "van der Schaaf", "L.", "" ], [ "van Heijningen", "J. V.", "" ], [ "van Veggel", "A. A.", "" ], [ "Vardaro", "M.", "" ], [ "Vass", "S.", "" ], [ "Vasúth", "M.", "" ], [ "Vaulin", "R.", "" ], [ "Vecchio", "A.", "" ], [ "Vedovato", "G.", "" ], [ "Veitch", "J.", "" ], [ "Veitch", "P. J.", "" ], [ "Venkateswara", "K.", "" ], [ "Verkindt", "D.", "" ], [ "Vetrano", "F.", "" ], [ "Viceré", "A.", "" ], [ "Vinciguerra", "S.", "" ], [ "Vine", "D. J.", "" ], [ "Vinet", "J. -Y.", "" ], [ "Vitale", "S.", "" ], [ "Vo", "T.", "" ], [ "Vocca", "H.", "" ], [ "Vorvick", "C.", "" ], [ "Voss", "D. V.", "" ], [ "Vousden", "W. D.", "" ], [ "Vyatchanin", "S. P.", "" ], [ "Wade", "A. R.", "" ], [ "Wade", "L. E.", "" ], [ "Wade", "M.", "" ], [ "Walker", "M.", "" ], [ "Wallace", "L.", "" ], [ "Walsh", "S.", "" ], [ "Wang", "G.", "" ], [ "Wang", "H.", "" ], [ "Wang", "M.", "" ], [ "Wang", "X.", "" ], [ "Wang", "Y.", "" ], [ "Ward", "R. L.", "" ], [ "Warner", "J.", "" ], [ "Was", "M.", "" ], [ "Weaver", "B.", "" ], [ "Wei", "L. -W.", "" ], [ "Weinert", "M.", "" ], [ "Weinstein", "A. J.", "" ], [ "Weiss", "R.", "" ], [ "Wen", "L.", "" ], [ "Wessels", "P.", "" ], [ "Westphal", "T.", "" ], [ "Wette", "K.", "" ], [ "Whelan", "J. T.", "" ], [ "Whiting", "B. F.", "" ], [ "Williams", "R. D.", "" ], [ "Williamson", "A. R.", "" ], [ "Willis", "J. L.", "" ], [ "Willke", "B.", "" ], [ "Wimmer", "M. H.", "" ], [ "Winkler", "W.", "" ], [ "Wipf", "C. C.", "" ], [ "Wiseman", "A. G.", "" ], [ "Wittel", "H.", "" ], [ "Woan", "G.", "" ], [ "Woehler", "J.", "" ], [ "Worden", "J.", "" ], [ "Wright", "J. L.", "" ], [ "Wu", "D. S.", "" ], [ "Wu", "G.", "" ], [ "Yablon", "J.", "" ], [ "Yam", "W.", "" ], [ "Yamamoto", "H.", "" ], [ "Yancey", "C. C.", "" ], [ "Yu", "H.", "" ], [ "Yvert", "M.", "" ], [ "zny", "A. Zadro.", "" ], [ "Zangrando", "L.", "" ], [ "Zanolin", "M.", "" ], [ "Zendri", "J. -P.", "" ], [ "Zevin", "M.", "" ], [ "Zhang", "L.", "" ], [ "Zhang", "M.", "" ], [ "Zhang", "Y.", "" ], [ "Zhao", "C.", "" ], [ "Zhou", "M.", "" ], [ "Zhou", "Z.", "" ], [ "Zhu", "X. J.", "" ], [ "Zucker", "M. E.", "" ], [ "Zuraw", "S. E.", "" ], [ "Zweizig", "J.", "" ] ]
The first direct gravitational-wave detection was made by the Advanced Laser Interferometer Gravitational Wave Observatory on September 14, 2015. The GW150914 signal was strong enough to be apparent, without using any waveform model, in the filtered detector strain data. Here, features of the signal visible in the data are analyzed using concepts from Newtonian physics and general relativity, accessible to anyone with a general physics background. The simple analysis presented here is consistent with the fully general-relativistic analyses published elsewhere,in showing that the signal was produced by the inspiral and subsequent merger of two black holes. The black holes were each of approximately 35 Msun, still orbited each other as close as ~350 km apart, and subsequently merged to form a single black hole. Similar reasoning, directly from the data, is used to roughly estimate how far these black holes were from the Earth, and the energy that they radiated in gravitational waves.
1609.04432
Stanley Deser
S. Deser
One-loop gravity divergences in D>4 cannot all be removed
Slightly xpanded, published, version
Gen Relativ Gravit (2016) 48:157
10.1007/s10714-016-2151-1
BRX-TH6308, CALT-TH2016-026
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Unlike the one-loop QG divergences in D=4, which can all be transformed away, those in arbitrary higher (even) dimension cannot.
[ { "created": "Wed, 14 Sep 2016 20:22:31 GMT", "version": "v1" }, { "created": "Thu, 10 Nov 2016 07:43:57 GMT", "version": "v2" } ]
2016-11-24
[ [ "Deser", "S.", "" ] ]
Unlike the one-loop QG divergences in D=4, which can all be transformed away, those in arbitrary higher (even) dimension cannot.
1512.03392
Sarp Akcay
Sarp Akcay and Maarten van de Meent
Numerical computation of the EOB potential q using self-force results
4 figures, numerical data at the end. Fixed the typos, added the journal reference
Phys. Rev. D 93, 064063 (2016)
10.1103/PhysRevD.93.064063
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The effective-one-body theory (EOB) describes the conservative dynamics of compact binary systems in terms of an effective Hamiltonian approach. The Hamiltonian for moderately eccentric motion of two non-spinning compact objects in the extreme mass-ratio limit is given in terms of three potentials: $a(v), \bar{d}(v), q(v)$. By generalizing the first law of mechanics for (non-spinning) black hole binaries to eccentric orbits, [\prd{\bf92}, 084021 (2015)] recently obtained new expressions for $\bar{d}(v)$ and $q(v)$ in terms of quantities that can be readily computed using the gravitational self-force approach. Using these expressions we present a new computation of the EOB potential $q(v)$ by combining results from two independent numerical self-force codes. We determine $q(v)$ for inverse binary separations in the range $1/1200 \le v \lesssim 1/6$. Our computation thus provides the first-ever strong-field results for $q(v)$. We also obtain $\bar{d}(v)$ in our entire domain to a fractional accuracy of $\gtrsim 10^{-8}$. We find to our results are compatible with the known post-Newtonian expansions for $\bar{d}(v)$ and $q(v)$ in the weak field, and agree with previous (less accurate) numerical results for $\bar{d}(v)$ in the strong field.
[ { "created": "Wed, 9 Dec 2015 20:11:54 GMT", "version": "v1" }, { "created": "Tue, 29 Mar 2016 11:22:45 GMT", "version": "v2" } ]
2016-03-30
[ [ "Akcay", "Sarp", "" ], [ "van de Meent", "Maarten", "" ] ]
The effective-one-body theory (EOB) describes the conservative dynamics of compact binary systems in terms of an effective Hamiltonian approach. The Hamiltonian for moderately eccentric motion of two non-spinning compact objects in the extreme mass-ratio limit is given in terms of three potentials: $a(v), \bar{d}(v), q(v)$. By generalizing the first law of mechanics for (non-spinning) black hole binaries to eccentric orbits, [\prd{\bf92}, 084021 (2015)] recently obtained new expressions for $\bar{d}(v)$ and $q(v)$ in terms of quantities that can be readily computed using the gravitational self-force approach. Using these expressions we present a new computation of the EOB potential $q(v)$ by combining results from two independent numerical self-force codes. We determine $q(v)$ for inverse binary separations in the range $1/1200 \le v \lesssim 1/6$. Our computation thus provides the first-ever strong-field results for $q(v)$. We also obtain $\bar{d}(v)$ in our entire domain to a fractional accuracy of $\gtrsim 10^{-8}$. We find to our results are compatible with the known post-Newtonian expansions for $\bar{d}(v)$ and $q(v)$ in the weak field, and agree with previous (less accurate) numerical results for $\bar{d}(v)$ in the strong field.
2003.00941
Luisa Bonolis PhD
Luisa Bonolis and Juan-Andres Leon
Gravitational-wave research as an emerging field in the Max Planck Society. The long roots of GEO600 and of the Albert Einstein Institute
94 pages. Enlarged version including new results from further archival research. A previous version appears as a chapter in the volume The Renaissance of General Relativity in Context, edited by A. Blum, R. Lalli and J. Renn (Boston: Birkhauser, 2020)
null
10.1007/978-3-030-50754-1
null
gr-qc physics.hist-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
On the occasion of the 50th anniversary since the beginning of the search for gravitational waves at the Max Planck Society, and in coincidence with the 25th anniversary of the foundation of the Albert Einstein Institute, we explore the interplay between the renaissance of general relativity and the advent of relativistic astrophysics following the German early involvement in gravitational-wave research, to the point when gravitational-wave detection became established by the appearance of full-scale detectors and international collaborations. On the background of the spectacular astrophysical discoveries of the 1960s and the growing role of relativistic astrophysics, Ludwig Biermann and his collaborators at the Max Planck Institute for Astrophysics in Munich became deeply involved in research related to such new horizons. At the end of the 1960s, Joseph Weber's announcements claiming detection of gravitational waves sparked the decisive entry of this group into the field, in parallel with the appointment of the renowned relativist Juergen Ehlers. The Munich area group of Max Planck institutes provided the fertile ground for acquiring a leading position in the 1970s, facilitating the experimental transition from resonant bars towards laser interferometry and its innovation at increasingly large scales, eventually moving to a dedicated site in Hannover in the early 1990s. The Hannover group emphasized perfecting experimental systems at pilot scales, and never developed a full-sized detector, rather joining the LIGO Scientific Collaboration at the end of the century. In parallel, the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) had been founded in Potsdam, and both sites, in Hannover and Potsdam, became a unified entity in the early 2000s and were central contributors to the first detection of gravitational waves in 2015.
[ { "created": "Mon, 2 Mar 2020 14:35:59 GMT", "version": "v1" }, { "created": "Thu, 29 Oct 2020 17:43:31 GMT", "version": "v2" } ]
2020-10-30
[ [ "Bonolis", "Luisa", "" ], [ "Leon", "Juan-Andres", "" ] ]
On the occasion of the 50th anniversary since the beginning of the search for gravitational waves at the Max Planck Society, and in coincidence with the 25th anniversary of the foundation of the Albert Einstein Institute, we explore the interplay between the renaissance of general relativity and the advent of relativistic astrophysics following the German early involvement in gravitational-wave research, to the point when gravitational-wave detection became established by the appearance of full-scale detectors and international collaborations. On the background of the spectacular astrophysical discoveries of the 1960s and the growing role of relativistic astrophysics, Ludwig Biermann and his collaborators at the Max Planck Institute for Astrophysics in Munich became deeply involved in research related to such new horizons. At the end of the 1960s, Joseph Weber's announcements claiming detection of gravitational waves sparked the decisive entry of this group into the field, in parallel with the appointment of the renowned relativist Juergen Ehlers. The Munich area group of Max Planck institutes provided the fertile ground for acquiring a leading position in the 1970s, facilitating the experimental transition from resonant bars towards laser interferometry and its innovation at increasingly large scales, eventually moving to a dedicated site in Hannover in the early 1990s. The Hannover group emphasized perfecting experimental systems at pilot scales, and never developed a full-sized detector, rather joining the LIGO Scientific Collaboration at the end of the century. In parallel, the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) had been founded in Potsdam, and both sites, in Hannover and Potsdam, became a unified entity in the early 2000s and were central contributors to the first detection of gravitational waves in 2015.
1812.01881
Boris Latosh
B. Latosh
Fab Four Effective Field Theory Treatment
11 pages
Eur. Phys. J. C (2018) 78: 991
10.1140/epjc/s10052-018-6470-0
null
gr-qc hep-th
http://creativecommons.org/licenses/by/4.0/
The article addresses the John interaction from Fab Four class of Horndeski models from the effective field theory point of view. Models with this interaction are heavily constrained by gravitational wave speed observations, so it is important to understand, if these constraints hold in the effective field theory framework. We show that John interaction induces new terms quadratic in curvature at the level of the effective (classical) action. These new terms generate additional low energy scalar and spin-2 gravitational degrees of freedom. Some of them have a non-vanishing decay width and some are ghosts. Discussion of these features is given
[ { "created": "Wed, 5 Dec 2018 09:57:24 GMT", "version": "v1" } ]
2018-12-06
[ [ "Latosh", "B.", "" ] ]
The article addresses the John interaction from Fab Four class of Horndeski models from the effective field theory point of view. Models with this interaction are heavily constrained by gravitational wave speed observations, so it is important to understand, if these constraints hold in the effective field theory framework. We show that John interaction induces new terms quadratic in curvature at the level of the effective (classical) action. These new terms generate additional low energy scalar and spin-2 gravitational degrees of freedom. Some of them have a non-vanishing decay width and some are ghosts. Discussion of these features is given
1902.08997
Fabio D'Ambrosio
Fabio D'Ambrosio
A Noether Theorem for discrete Covariant Mechanics
11 pages, 2 figures
null
null
null
gr-qc hep-lat
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Noether's theorem is an elegant and powerful tool of classical mechanics, but it is of little to no consequence in discrete theories. Here we define and explore a discrete approach to covariant mechanics and show that within this framework a discrete version of Noether's theorem, completely analogous to the well-known continuum version with all its ramifications, remains valid. We also discuss why more traditional approaches to discretized mechanics violate certain conservation laws by construction.
[ { "created": "Sun, 24 Feb 2019 19:29:50 GMT", "version": "v1" } ]
2019-02-26
[ [ "D'Ambrosio", "Fabio", "" ] ]
Noether's theorem is an elegant and powerful tool of classical mechanics, but it is of little to no consequence in discrete theories. Here we define and explore a discrete approach to covariant mechanics and show that within this framework a discrete version of Noether's theorem, completely analogous to the well-known continuum version with all its ramifications, remains valid. We also discuss why more traditional approaches to discretized mechanics violate certain conservation laws by construction.
gr-qc/0305063
Parampreet Singh
Jeeva Anandan, Naresh Dadhich, Parampreet Singh
Action based approach to the dynamics of extended bodies in General Relativity
This essay received an ``honorable mention'' in the 2003 Gravity Research Foundation essay competition
Int.J.Mod.Phys. D12 (2003) 1651-1656
10.1142/S0218271803003931
null
gr-qc astro-ph hep-th quant-ph
null
We present, for the first time, an action principle that gives the equations of motion of an extended body possessing multipole moments in an external gravitational field, in the weak field limit. From the action, the experimentally observable quantum phase shifts in the wavefunction of an extended object due to the coupling of its multipole moments with the gravitational field are obtained. Also, since the theory may be quantized using the action, the present approach is useful in the interface between general relativity and quantum mechanics.
[ { "created": "Fri, 16 May 2003 06:46:29 GMT", "version": "v1" } ]
2009-11-10
[ [ "Anandan", "Jeeva", "" ], [ "Dadhich", "Naresh", "" ], [ "Singh", "Parampreet", "" ] ]
We present, for the first time, an action principle that gives the equations of motion of an extended body possessing multipole moments in an external gravitational field, in the weak field limit. From the action, the experimentally observable quantum phase shifts in the wavefunction of an extended object due to the coupling of its multipole moments with the gravitational field are obtained. Also, since the theory may be quantized using the action, the present approach is useful in the interface between general relativity and quantum mechanics.
2308.05719
Supragyan Priyadarshinee
Supragyan Priyadarshinee
Quasi-normal mode of dyonic hairy black hole and its interplay with phase transitions
29 pages, 45 Figures. arXiv admin note: text overlap with arXiv:2108.02514
null
null
null
gr-qc hep-th
http://creativecommons.org/licenses/by/4.0/
We study the dynamical stability of hairy dyonic black holes in the Einstein-Maxwell-scalar gravity system against the massless scalar field perturbation. We numerically obtain the corresponding quasinormal modes (QNMs) using the series solution and shooting methods for various black hole parameters. We find that the numerical values obtained from these two methods agree well with each other. The imaginary part of the QNM is always negative, indicating the stability of the dyonic hairy black hole against the scalar perturbation. We find that the decay and oscillatory modes of the scalar field perturbation increase linearly with the horizon radius for large black holes. We thoroughly investigate the behaviour of QNMs for different values of black hole parameters, including the electric charge, magnetic charge, horizon radius and hairy parameter, etc. Moreover, we also analyse the QNM near the small/large black hole phase transition and find that the nature of the QNMs is different for large and small black hole phases, suggesting QNMs as the possible probe of black hole phase transition.
[ { "created": "Thu, 10 Aug 2023 17:35:01 GMT", "version": "v1" }, { "created": "Fri, 11 Aug 2023 11:28:05 GMT", "version": "v2" } ]
2023-08-14
[ [ "Priyadarshinee", "Supragyan", "" ] ]
We study the dynamical stability of hairy dyonic black holes in the Einstein-Maxwell-scalar gravity system against the massless scalar field perturbation. We numerically obtain the corresponding quasinormal modes (QNMs) using the series solution and shooting methods for various black hole parameters. We find that the numerical values obtained from these two methods agree well with each other. The imaginary part of the QNM is always negative, indicating the stability of the dyonic hairy black hole against the scalar perturbation. We find that the decay and oscillatory modes of the scalar field perturbation increase linearly with the horizon radius for large black holes. We thoroughly investigate the behaviour of QNMs for different values of black hole parameters, including the electric charge, magnetic charge, horizon radius and hairy parameter, etc. Moreover, we also analyse the QNM near the small/large black hole phase transition and find that the nature of the QNMs is different for large and small black hole phases, suggesting QNMs as the possible probe of black hole phase transition.
gr-qc/9512038
Daniel Mueller S.
Daniel Mueller
A Semi-Analytical Method for the Evaluation of the Power Spectrum of a Rotating Observer
6 pages, 4 figures
null
null
null
gr-qc
null
In this letter we propose a semi-analitical method of evaluation of the power spectrum of a circular moving Unruh-type detector using the method of residue and compare the spectrum with the already known result in the relativistic limit.
[ { "created": "Wed, 20 Dec 1995 22:20:39 GMT", "version": "v1" } ]
2007-05-23
[ [ "Mueller", "Daniel", "" ] ]
In this letter we propose a semi-analitical method of evaluation of the power spectrum of a circular moving Unruh-type detector using the method of residue and compare the spectrum with the already known result in the relativistic limit.
2001.05909
Jiong Lin
Jiong Lin, Qing Gao, Yungui Gong, Yizhou Lu, Chao Zhang, Fengge Zhang
Primordial black holes and secondary gravitational waves from k/G inflation
null
Phys. Rev. D 101, 103515 (2020)
10.1103/PhysRevD.101.103515
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The possibility that in the mass range around $10^{-12}\ M_\odot$ most of dark matter constitutes of primordial black holes (PBHs) is a very interesting topic. To produce PBHs with this mass, the primordial scalar power spectrum needs to be enhanced to the order of 0.01 at the scale $k\sim 10^{12}\ \text{Mpc}^{-1}$. The enhanced power spectrum also produces large secondary gravitational waves at the mHz band. A phenomenological delta function power spectrum is usually used to discuss the production of PBHs and secondary gravitational waves. Based on G and k inflations, we propose a new mechanism to enhance the power spectrum at small scales by introducing a non-canonical kinetic term $[1-2G(\phi)]X$ with the function $G(\phi)$ having a peak. Away from the peak, $G(\phi)$ is negligible and we recover the usual slow-roll inflation which is constrained by the cosmic microwave background anisotrpy observations. Around the peak, the slow-roll inflation transiently turns to ultra slow-roll inflation. The enhancement of the power spectrum can be obtained with generic potentials, and there is no need to fine tune the parameters in $G(\phi)$. The energy spectrum $\Omega_{GW}(f)$ of secondary gravitational waves have the characteristic power law behaviour $\Omega_{GW}(f)\sim f^{n}$ and is testable by pulsar timing array and space based gravitational wave detectors.
[ { "created": "Thu, 16 Jan 2020 15:53:44 GMT", "version": "v1" }, { "created": "Fri, 24 Apr 2020 10:05:27 GMT", "version": "v2" } ]
2020-05-15
[ [ "Lin", "Jiong", "" ], [ "Gao", "Qing", "" ], [ "Gong", "Yungui", "" ], [ "Lu", "Yizhou", "" ], [ "Zhang", "Chao", "" ], [ "Zhang", "Fengge", "" ] ]
The possibility that in the mass range around $10^{-12}\ M_\odot$ most of dark matter constitutes of primordial black holes (PBHs) is a very interesting topic. To produce PBHs with this mass, the primordial scalar power spectrum needs to be enhanced to the order of 0.01 at the scale $k\sim 10^{12}\ \text{Mpc}^{-1}$. The enhanced power spectrum also produces large secondary gravitational waves at the mHz band. A phenomenological delta function power spectrum is usually used to discuss the production of PBHs and secondary gravitational waves. Based on G and k inflations, we propose a new mechanism to enhance the power spectrum at small scales by introducing a non-canonical kinetic term $[1-2G(\phi)]X$ with the function $G(\phi)$ having a peak. Away from the peak, $G(\phi)$ is negligible and we recover the usual slow-roll inflation which is constrained by the cosmic microwave background anisotrpy observations. Around the peak, the slow-roll inflation transiently turns to ultra slow-roll inflation. The enhancement of the power spectrum can be obtained with generic potentials, and there is no need to fine tune the parameters in $G(\phi)$. The energy spectrum $\Omega_{GW}(f)$ of secondary gravitational waves have the characteristic power law behaviour $\Omega_{GW}(f)\sim f^{n}$ and is testable by pulsar timing array and space based gravitational wave detectors.
gr-qc/0102059
Bijan Saha
Bijan Saha (LIT, JINR) and G.N. Shikin (RPFU)
On the role of $\Lambda$-term in the evolution of Bianchi-I cosmological model with nonlinear spinor field
RevTex, 4 pages
PFU Reports: Physics, N 8, issue 1, (2000) 17-20
null
null
gr-qc
null
Self-consistent solutions to nonlinear spinor field equations in General Relativity are studied for the case of Bianchi type-I space-time. It has been shown that introduction of $\Lambda$-term in the Lagrangian generates oscillations of the Bianchi type-I model.
[ { "created": "Tue, 13 Feb 2001 12:57:48 GMT", "version": "v1" } ]
2015-05-01
[ [ "Saha", "Bijan", "", "LIT, JINR" ], [ "Shikin", "G. N.", "", "RPFU" ] ]
Self-consistent solutions to nonlinear spinor field equations in General Relativity are studied for the case of Bianchi type-I space-time. It has been shown that introduction of $\Lambda$-term in the Lagrangian generates oscillations of the Bianchi type-I model.
1910.06889
Isha Kotecha
Mehdi Assanioussi and Isha Kotecha
Thermal representations in group field theory: squeezed vacua and quantum gravity condensates
v2, 11 pages, minor revisions, published version; v1, 10 pages
JHEP 2020, 173 (2020)
10.1007/JHEP02(2020)173
null
gr-qc hep-th quant-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We apply the formalism of thermofield dynamics to group field theory quantum gravity and construct thermal representations associated with generalised equilibrium Gibbs states using Bogoliubov transformations. The newly constructed class of thermal vacua are entangled, two-mode squeezed, thermofield double states. The corresponding finite temperature representations are inequivalent to the standard zero temperature one based on a degenerate vacuum. An interesting class of states, coherent thermal states, are defined and understood as thermal quantum gravity condensates.
[ { "created": "Tue, 15 Oct 2019 16:05:10 GMT", "version": "v1" }, { "created": "Mon, 2 Mar 2020 18:51:46 GMT", "version": "v2" } ]
2020-03-03
[ [ "Assanioussi", "Mehdi", "" ], [ "Kotecha", "Isha", "" ] ]
We apply the formalism of thermofield dynamics to group field theory quantum gravity and construct thermal representations associated with generalised equilibrium Gibbs states using Bogoliubov transformations. The newly constructed class of thermal vacua are entangled, two-mode squeezed, thermofield double states. The corresponding finite temperature representations are inequivalent to the standard zero temperature one based on a degenerate vacuum. An interesting class of states, coherent thermal states, are defined and understood as thermal quantum gravity condensates.
1903.08844
LSC P&P Committee
The LIGO Scientific Collaboration and the Virgo Collaboration: B. P. Abbott, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, C. Adams, R. X. Adhikari, V. B. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, G. Allen, A. Allocca, M. A. Aloy, P. A. Altin, A. Amato, A. Ananyeva, S. B. Anderson, W. G. Anderson, S. V. Angelova, S. Antier, S. Appert, K. Arai, M. C. Araya, J. S. Areeda, M. Ar\`ene, N. Arnaud, S. Ascenzi, G. Ashton, S. M. Aston, P. Astone, F. Aubin, P. Aufmuth, K. AultONeal, C. Austin, V. Avendano, A. Avila-Alvarez, S. Babak, P. Bacon, F. Badaracco, M. K. M. Bader, S. Bae, P. T. Baker, F. Baldaccini, G. Ballardin, S. W. Ballmer, S. Banagiri, J. C. Barayoga, S. E. Barclay, B. C. Barish, D. Barker, K. Barkett, S. Barnum, F. Barone, B. Barr, L. Barsotti, M. Barsuglia, D. Barta, J. Bartlett, I. Bartos, R. Bassiri, A. Basti, M. Bawaj, J. C. Bayley, M. Bazzan, B. B\'ecsy, M. Bejger, I. Belahcene, A. S. Bell, D. Beniwal, B. K. Berger, G. Bergmann, S. Bernuzzi, J. J. Bero, C. P. L. Berry, D. Bersanetti, A. Bertolini, J. Betzwieser, R. Bhandare, J. Bidler, I. A. Bilenko, S. A. Bilgili, G. Billingsley, J. Birch, R. Birney, O. Birnholtz, S. Biscans, S. Biscoveanu, A. Bisht, M. Bitossi, M. A. Bizouard, J. K. Blackburn, C. D. Blair, D. G. Blair, R. M. Blair, S. Bloemen, N. Bode, M. Boer, Y. Boetzel, G. Bogaert, F. Bondu, E. Bonilla, R. Bonnand, P. Booker, B. A. Boom, C. D. Booth, R. Bork, V. Boschi, S. Bose, K. Bossie, V. Bossilkov, J. Bosveld, Y. Bouffanais, A. Bozzi, C. Bradaschia, P. R. Brady, A. Bramley, M. Branchesi, J. E. Brau, T. Briant, J. H. Briggs, F. Brighenti, A. Brillet, M. Brinkmann, V. Brisson, P. Brockill, A. F. Brooks, D. D. Brown, S. Brunett, A. Buikema, T. Bulik, H. J. Bulten, A. Buonanno, D. Buskulic, C. Buy, R. L. Byer, M. Cabero, L. Cadonati, G. Cagnoli, C. Cahillane, J. Calder\'on Bustillo, T. A. Callister, E. Calloni, J. B. Camp, W. A. Campbell, M. Canepa, K. C. Cannon, H. Cao, J. Cao, E. Capocasa, F. Carbognani, S. Caride, M. F. Carney, G. Carullo, J. Casanueva Diaz, C. Casentini, S. Caudill, M. Cavagli\`a, F. Cavalier, R. Cavalieri, G. Cella, P. Cerd\'a-Dur\'an, G. Cerretani, E. Cesarini, O. Chaibi, K. Chakravarti, S. J. Chamberlin, M. Chan, S. Chao, P. Charlton, E. A. Chase, E. Chassande-Mottin, D. Chatterjee, M. Chaturvedi, B. D. Cheeseboro, H. Y. Chen, X. Chen, Y. Chen, H.-P. Cheng, C. K. Cheong, H. Y. Chia, A. Chincarini, A. Chiummo, G. Cho, H. S. Cho, M. Cho, N. Christensen, Q. Chu, S. Chua, K. W. Chung, S. Chung, G. Ciani, A. A. Ciobanu, R. Ciolfi, F. Cipriano, A. Cirone, F. Clara, J. A. Clark, P. Clearwater, F. Cleva, C. Cocchieri, E. Coccia, P.-F. Cohadon, D. Cohen, R. Colgan, M. Colleoni, C. G. Collette, C. Collins, L. R. Cominsky, M. Constancio Jr., L. Conti, S. J. Cooper, P. Corban, T. R. Corbitt, I. Cordero-Carri\'on, K. R. Corley, N. Cornish, A. Corsi, S. Cortese, C. A. Costa, R. Cotesta, M. W. Coughlin, S. B. Coughlin, J.-P. Coulon, S. T. Countryman, P. Couvares, P. B. Covas, E. E. Cowan, D. M. Coward, M. J. Cowart, D. C. Coyne, R. Coyne, J. D. E. Creighton, T. D. Creighton, J. Cripe, M. Croquette, S. G. Crowder, T. J. Cullen, A. Cumming, L. Cunningham, E. Cuoco, T. Dal Canton, G. D\'alya, S. L. Danilishin, S. D'Antonio, K. Danzmann, A. Dasgupta, C. F. Da Silva Costa, L. E. H. Datrier, V. Dattilo, I. Dave, M. Davier, D. Davis, E. J. Daw, D. DeBra, M. Deenadayalan, J. Degallaix, M. De Laurentis, S. Del\'eglise, W. Del Pozzo, L. M. DeMarchi, N. Demos, T. Dent, R. De Pietri, J. Derby, R. De Rosa, C. De Rossi, R. DeSalvo, O. de Varona, S. Dhurandhar, M. C. D\'iaz, T. Dietrich, L. Di Fiore, M. Di Giovanni, T. Di Girolamo, A. Di Lieto, B. Ding, S. Di Pace, I. Di Palma, F. Di Renzo, A. Dmitriev, Z. Doctor, F. Donovan, K. L. Dooley, S. Doravari, I. Dorrington, T. P. Downes, M. Drago, J. C. Driggers, Z. Du, J.-G. Ducoin, P. Dupej, I. Dvorkin, S. E. Dwyer, P. J. Easter, T. B. Edo, M. C. Edwards, A. Effler, P. Ehrens, J. Eichholz, S. S. Eikenberry, M. Eisenmann, R. A. Eisenstein, R. C. Essick, H. Estelles, D. Estevez, Z. B. Etienne, T. Etzel, M. Evans, T. M. Evans, V. Fafone, H. Fair, S. Fairhurst, X. Fan, S. Farinon, B. Farr, W. M. Farr, E. J. Fauchon-Jones, M. Favata, M. Fays, M. Fazio, C. Fee, J. Feicht, M. M. Fejer, F. Feng, A. Fernandez-Galiana, I. Ferrante, E. C. Ferreira, T. A. Ferreira, F. Ferrini, F. Fidecaro, I. Fiori, D. Fiorucci, M. Fishbach, R. P. Fisher, J. M. Fishner, M. Fitz-Axen, R. Flaminio, M. Fletcher, E. Flynn, H. Fong, J. A. Font, P. W. F. Forsyth, J.-D. Fournier, S. Frasca, F. Frasconi, Z. Frei, A. Freise, R. Frey, V. Frey, P. Fritschel, V. V. Frolov, P. Fulda, M. Fyffe, H. A. Gabbard, B. U. Gadre, S. M. Gaebel, J. R. Gair, L. Gammaitoni, M. R. Ganija, S. G. Gaonkar, A. Garcia, C. Garc\'ia-Quir\'os, F. Garufi, B. Gateley, S. Gaudio, G. Gaur, V. Gayathri, G. Gemme, E. Genin, A. Gennai, D. George, J. George, L. Gergely, V. Germain, S. Ghonge, Abhirup Ghosh, Archisman Ghosh, S. Ghosh, B. Giacomazzo, J. A. Giaime, K. D. Giardina, A. Giazotto, K. Gill, G. Giordano, L. Glover, P. Godwin, E. Goetz, R. Goetz, B. Goncharov, G. Gonz\'alez, J. M. Gonzalez Castro, A. Gopakumar, M. L. Gorodetsky, S. E. Gossan, M. Gosselin, R. Gouaty, A. Grado, C. Graef, M. Granata, A. Grant, S. Gras, P. Grassia, C. Gray, R. Gray, G. Greco, A. C. Green, R. Green, E. M. Gretarsson, P. Groot, H. Grote, S. Grunewald, P. Gruning, G. M. Guidi, H. K. Gulati, Y. Guo, A. Gupta, M. K. Gupta, E. K. Gustafson, R. Gustafson, L. Haegel, O. Halim, B. R. Hall, E. D. Hall, E. Z. Hamilton, G. Hammond, M. Haney, M. M. Hanke, J. Hanks, C. Hanna, O. A. Hannuksela, J. Hanson, T. Hardwick, K. Haris, J. Harms, G. M. Harry, I. W. Harry, C.-J. Haster, K. Haughian, F. J. Hayes, J. Healy, A. Heidmann, M. C. Heintze, H. Heitmann, P. Hello, G. Hemming, M. Hendry, I. S. Heng, J. Hennig, A. W. Heptonstall, Francisco Hernandez Vivanco, M. Heurs, S. Hild, T. Hinderer, D. Hoak, S. Hochheim, D. Hofman, A. M. Holgado, N. A. Holland, K. Holt, D. E. Holz, P. Hopkins, C. Horst, J. Hough, E. J. Howell, C. G. Hoy, A. Hreibi, E. A. Huerta, D. Huet, B. Hughey, M. Hulko, S. Husa, S. H. Huttner, T. Huynh-Dinh, B. Idzkowski, A. Iess, C. Ingram, R. Inta, G. Intini, B. Irwin, H. N. Isa, J.-M. Isac, M. Isi, B. R. Iyer, K. Izumi, T. Jacqmin, S. J. Jadhav, K. Jani, N. N. Janthalur, P. Jaranowski, A. C. Jenkins, J. Jiang, D. S. Johnson, A. W. Jones, D. I. Jones, R. Jones, R. J. G. Jonker, L. Ju, J. Junker, C. V. Kalaghatgi, V. Kalogera, B. Kamai, S. Kandhasamy, G. Kang, J. B. Kanner, S. J. Kapadia, S. Karki, K. S. Karvinen, R. Kashyap, M. Kasprzack, S. Katsanevas, E. Katsavounidis, W. Katzman, S. Kaufer, K. Kawabe, N. V. Keerthana, F. K\'ef\'elian, D. Keitel, R. Kennedy, J. S. Key, F. Y. Khalili, H. Khan, I. Khan, S. Khan, Z. Khan, E. A. Khazanov, M. Khursheed, N. Kijbunchoo, Chunglee Kim, J. C. Kim, K. Kim, W. Kim, W. S. Kim, Y.-M. Kim, C. Kimball, E. J. King, P. J. King, M. Kinley-Hanlon, R. Kirchhoff, J. S. Kissel, L. Kleybolte, J. H. Klika, S. Klimenko, T. D. Knowles, P. Koch, S. M. Koehlenbeck, G. Koekoek, S. Koley, V. Kondrashov, A. Kontos, N. Koper, M. Korobko, W. Z. Korth, I. Kowalska, D. B. Kozak, V. Kringel, N. Krishnendu, A. Kr\'olak, G. Kuehn, A. Kumar, P. Kumar, R. Kumar, S. Kumar, L. Kuo, A. Kutynia, S. Kwang, B. D. Lackey, K. H. Lai, T. L. Lam, M. Landry, B. B. Lane, R. N. Lang, J. Lange, B. Lantz, R. K. Lanza, A. Lartaux-Vollard, P. D. Lasky, M. Laxen, A. Lazzarini, C. Lazzaro, P. Leaci, S. Leavey, Y. K. Lecoeuche, C. H. Lee, H. K. Lee, H. M. Lee, H. W. Lee, J. Lee, K. Lee, J. Lehmann, A. Lenon, N. Leroy, N. Letendre, Y. Levin, J. Li, K. J. L. Li, T. G. F. Li, X. Li, F. Lin, F. Linde, S. D. Linker, T. B. Littenberg, J. Liu, X. Liu, R. K. L. Lo, N. A. Lockerbie, L. T. London, A. Longo, M. Lorenzini, V. Loriette, M. Lormand, G. Losurdo, J. D. Lough, C. O. Lousto, G. Lovelace, M. E. Lower, H. L\"uck, D. Lumaca, A. P. Lundgren, R. Lynch, Y. Ma, R. Macas, S. Macfoy, M. MacInnis, D. M. Macleod, A. Macquet, F. Maga\~na-Sandoval, L. Maga\~na Zertuche, R. M. Magee, E. Majorana, I. Maksimovic, A. Malik, N. Man, V. Mandic, V. Mangano, G. L. Mansell, M. Manske, M. Mantovani, F. Marchesoni, F. Marion, S. M\'arka, Z. M\'arka, C. Markakis, A. S. Markosyan, A. Markowitz, E. Maros, A. Marquina, S. Marsat, F. Martelli, I. W. Martin, R. M. Martin, D. V. Martynov, K. Mason, E. Massera, A. Masserot, T. J. Massinger, M. Masso-Reid, S. Mastrogiovanni, A. Matas, F. Matichard, L. Matone, N. Mavalvala, N. Mazumder, J. J. McCann, R. McCarthy, D. E. McClelland, S. McCormick, L. McCuller, S. C. McGuire, J. McIver, D. J. McManus, T. McRae, S. T. McWilliams, D. Meacher, G. D. Meadors, M. Mehmet, A. K. Mehta, J. Meidam, A. Melatos, G. Mendell, R. A. Mercer, L. Mereni, E. L. Merilh, M. Merzougui, S. Meshkov, C. Messenger, C. Messick, R. Metzdorff, P. M. Meyers, H. Miao, C. Michel, H. Middleton, E. E. Mikhailov, L. Milano, A. L. Miller, A. Miller, M. Millhouse, J. C. Mills, M. C. Milovich-Goff, O. Minazzoli, Y. Minenkov, A. Mishkin, C. Mishra, T. Mistry, S. Mitra, V. P. Mitrofanov, G. Mitselmakher, R. Mittleman, G. Mo, D. Moffa, K. Mogushi, S. R. P. Mohapatra, M. Montani, C. J. Moore, D. Moraru, G. Moreno, S. Morisaki, B. Mours, C. M. Mow-Lowry, Arunava Mukherjee, D. Mukherjee, S. Mukherjee, N. Mukund, A. Mullavey, J. Munch, E. A. Mu\~niz, M. Muratore, P. G. Murray, A. Nagar, I. Nardecchia, L. Naticchioni, R. K. Nayak, J. Neilson, G. Nelemans, T. J. N. Nelson, M. Nery, A. Neunzert, K. Y. Ng, S. Ng, P. Nguyen, D. Nichols, S. Nissanke, F. Nocera, C. North, L. K. Nuttall, M. Obergaulinger, J. Oberling, B. D. O'Brien, G. D. O'Dea, G. H. Ogin, J. J. Oh, S. H. Oh, F. Ohme, H. Ohta, M. A. Okada, M. Oliver, P. Oppermann, Richard J. Oram, B. O'Reilly, R. G. Ormiston, L. F. Ortega, R. O'Shaughnessy, S. Ossokine, D. J. Ottaway, H. Overmier, B. J. Owen, A. E. Pace, G. Pagano, M. A. Page, A. Pai, S. A. Pai, J. R. Palamos, O. Palashov, C. Palomba, A. Pal-Singh, Huang-Wei Pan, B. Pang, P. T. H. Pang, C. Pankow, F. Pannarale, B. C. Pant, F. Paoletti, A. Paoli, A. Parida, W. Parker, D. Pascucci, A. Pasqualetti, R. Passaquieti, D. Passuello, M. Patil, B. Patricelli, B. L. Pearlstone, C. Pedersen, M. Pedraza, R. Pedurand, A. Pele, S. Penn, C. J. Perez, A. Perreca, H. P. Pfeiffer, M. Phelps, K. S. Phukon, O. J. Piccinni, M. Pichot, F. Piergiovanni, G. Pillant, L. Pinard, M. Pirello, M. Pitkin, R. Poggiani, D. Y. T. Pong, S. Ponrathnam, P. Popolizio, E. K. Porter, J. Powell, A. K. Prajapati, J. Prasad, K. Prasai, R. Prasanna, G. Pratten, T. Prestegard, S. Privitera, G. A. Prodi, L. G. Prokhorov, O. Puncken, M. Punturo, P. Puppo, M. P\"urrer, H. Qi, V. Quetschke, P. J. Quinonez, E. A. Quintero, R. Quitzow-James, F. J. Raab, H. Radkins, N. Radulescu, P. Raffai, S. Raja, C. Rajan, B. Rajbhandari, M. Rakhmanov, K. E. Ramirez, A. Ramos-Buades, Javed Rana, K. Rao, P. Rapagnani, V. Raymond, M. Razzano, J. Read, T. Regimbau, L. Rei, S. Reid, D. H. Reitze, W. Ren, F. Ricci, C. J. Richardson, J. W. Richardson, P. M. Ricker, K. Riles, M. Rizzo, N. A. Robertson, R. Robie, F. Robinet, A. Rocchi, L. Rolland, J. G. Rollins, V. J. Roma, M. Romanelli, J. D. Romano, R. Romano, C. L. Romel, J. H. Romie, K. Rose, D. Rosi\'nska, S. G. Rosofsky, M. P. Ross, S. Rowan, A. R\"udiger, P. Ruggi, G. Rutins, K. Ryan, S. Sachdev, T. Sadecki, M. Sakellariadou, L. Salconi, M. Saleem, A. Samajdar, L. Sammut, E. J. Sanchez, L. E. Sanchez, N. Sanchis-Gual, V. Sandberg, J. R. Sanders, K. A. Santiago, N. Sarin, B. Sassolas, P. R. Saulson, O. Sauter, R. L. Savage, P. Schale, M. Scheel, J. Scheuer, P. Schmidt, R. Schnabel, R. M. S. Schofield, A. Sch\"onbeck, E. Schreiber, B. W. Schulte, B. F. Schutz, S. G. Schwalbe, J. Scott, S. M. Scott, E. Seidel, D. Sellers, A. S. Sengupta, N. Sennett, D. Sentenac, V. Sequino, A. Sergeev, Y. Setyawati, D. A. Shaddock, T. Shaffer, M. S. Shahriar, M. B. Shaner, L. Shao, P. Sharma, P. Shawhan, H. Shen, R. Shink, D. H. Shoemaker, D. M. Shoemaker, S. ShyamSundar, K. Siellez, M. Sieniawska, D. Sigg, A. D. Silva, L. P. Singer, N. Singh, A. Singhal, A. M. Sintes, S. Sitmukhambetov, V. Skliris, B. J. J. Slagmolen, T. J. Slaven-Blair, J. R. Smith, R. J. E. Smith, S. Somala, E. J. Son, B. Sorazu, F. Sorrentino, T. Souradeep, E. Sowell, A. P. Spencer, A. K. Srivastava, V. Srivastava, K. Staats, C. Stachie, M. Standke, D. A. Steer, M. Steinke, J. Steinlechner, S. Steinlechner, D. Steinmeyer, S. P. Stevenson, D. Stocks, R. Stone, D. J. Stops, K. A. Strain, G. Stratta, S. E. Strigin, A. Strunk, R. Sturani, A. L. Stuver, V. Sudhir, T. Z. Summerscales, L. Sun, S. Sunil, J. Suresh, P. J. Sutton, B. L. Swinkels, M. J. Szczepa\'nczyk, M. Tacca, S. C. Tait, C. Talbot, D. Talukder, D. B. Tanner, M. T\'apai, A. Taracchini, J. D. Tasson, R. Taylor, F. Thies, M. Thomas, P. Thomas, S. R. Thondapu, K. A. Thorne, E. Thrane, Shubhanshu Tiwari, Srishti Tiwari, V. Tiwari, K. Toland, M. Tonelli, Z. Tornasi, A. Torres-Forn\'e, C. I. Torrie, D. T\"oyr\"a, F. Travasso, G. Traylor, M. C. Tringali, A. Trovato, L. Trozzo, R. Trudeau, K. W. Tsang, M. Tse, R. Tso, L. Tsukada, D. Tsuna, D. Tuyenbayev, K. Ueno, D. Ugolini, C. S. Unnikrishnan, A. L. Urban, S. A. Usman, H. Vahlbruch, G. Vajente, G. Valdes, N. van Bakel, M. van Beuzekom, J. F. J. van den Brand, C. Van Den Broeck, D. C. Vander-Hyde, J. V. van Heijningen, L. van der Schaaf, A. A. van Veggel, M. Vardaro, V. Varma, S. Vass, M. Vas\'uth, A. Vecchio, G. Vedovato, J. Veitch, P. J. Veitch, K. Venkateswara, G. Venugopalan, D. Verkindt, F. Vetrano, A. Vicer\'e, A. D. Viets, D. J. Vine, J.-Y. Vinet, S. Vitale, T. Vo, H. Vocca, C. Vorvick, S. P. Vyatchanin, A. R. Wade, L. E. Wade, M. Wade, R. Walet, M. Walker, L. Wallace, S. Walsh, G. Wang, H. Wang, J. Z. Wang, W. H. Wang, Y. F. Wang, R. L. Ward, Z. A. Warden, J. Warner, M. Was, J. Watchi, B. Weaver, L.-W. Wei, M. Weinert, A. J. Weinstein, R. Weiss, F. Wellmann, L. Wen, E. K. Wessel, P. We{\ss}els, J. W. Westhouse, K. Wette, J. T. Whelan, B. F. Whiting, C. Whittle, D. M. Wilken, D. Williams, A. R. Williamson, J. L. Willis, B. Willke, M. H. Wimmer, W. Winkler, C. C. Wipf, H. Wittel, G. Woan, J. Woehler, J. K. Wofford, J. Worden, J. L. Wright, D. S. Wu, D. M. Wysocki, L. Xiao, R. Xu, H. Yamamoto, C. C. Yancey, L. Yang, M. J. Yap, M. Yazback, D. W. Yeeles, Hang Yu, Haocun Yu, S. H. R. Yuen, M. Yvert, A. K. Zadro\.zny, M. Zanolin, T. Zelenova, J.-P. Zendri, M. Zevin, J. Zhang, L. Zhang, T. Zhang, C. Zhao, M. Zhou, Z. Zhou, X. J. Zhu, M. E. Zucker, J. Zweizig
Directional limits on persistent gravitational waves using data from Advanced LIGO's first two observing runs
15 pages, 5 figures
Phys. Rev. D 100, 062001 (2019)
10.1103/PhysRevD.100.062001
LIGO-P1900053
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We perform an unmodeled search for persistent, directional gravitational wave (GW) sources using data from the first and second observing runs of Advanced LIGO. We do not find evidence for any GW signals. We place limits on the broadband GW flux emitted at 25~Hz from point sources with a power law spectrum at $F_{\alpha,\Theta} <(0.05-25)\times 10^{-8} ~{\rm erg\,cm^{-2}\,s^{-1}\,Hz^{-1}}$ and the (normalized) energy density spectrum in GWs at 25 Hz from extended sources at $\Omega_{\alpha}(\Theta) <(0.19-2.89)\times 10^{-8} ~{\rm sr^{-1}}$ where $\alpha$ is the spectral index of the energy density spectrum. These represent improvements of $2.5-3\times$ over previous limits. We also consider point sources emitting GWs at a single frequency, targeting the directions of Sco X-1, SN 1987A, and the Galactic Center. The best upper limits on the strain amplitude of a potential source in these three directions range from $h_0 < (3.6-4.7)\times 10^{-25}$, 1.5$\times$ better than previous limits set with the same analysis method. We also report on a marginally significant outlier at 36.06~Hz. This outlier is not consistent with a persistent gravitational-wave source as its significance diminishes when combining all of the available data.
[ { "created": "Thu, 21 Mar 2019 06:30:00 GMT", "version": "v1" }, { "created": "Thu, 18 Apr 2019 07:55:49 GMT", "version": "v2" }, { "created": "Mon, 9 Sep 2019 06:17:36 GMT", "version": "v3" } ]
2019-09-11
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J.", "" ], [ "Radkins", "H.", "" ], [ "Radulescu", "N.", "" ], [ "Raffai", "P.", "" ], [ "Raja", "S.", "" ], [ "Rajan", "C.", "" ], [ "Rajbhandari", "B.", "" ], [ "Rakhmanov", "M.", "" ], [ "Ramirez", "K. E.", "" ], [ "Ramos-Buades", "A.", "" ], [ "Rana", "Javed", "" ], [ "Rao", "K.", "" ], [ "Rapagnani", "P.", "" ], [ "Raymond", "V.", "" ], [ "Razzano", "M.", "" ], [ "Read", "J.", "" ], [ "Regimbau", "T.", "" ], [ "Rei", "L.", "" ], [ "Reid", "S.", "" ], [ "Reitze", "D. H.", "" ], [ "Ren", "W.", "" ], [ "Ricci", "F.", "" ], [ "Richardson", "C. J.", "" ], [ "Richardson", "J. W.", "" ], [ "Ricker", "P. M.", "" ], [ "Riles", "K.", "" ], [ "Rizzo", "M.", "" ], [ "Robertson", "N. A.", "" ], [ "Robie", "R.", "" ], [ "Robinet", "F.", "" ], [ "Rocchi", "A.", "" ], [ "Rolland", "L.", "" ], [ "Rollins", "J. G.", "" ], [ "Roma", "V. J.", "" ], [ "Romanelli", "M.", "" ], [ "Romano", "J. D.", "" ], [ "Romano", "R.", "" ], [ "Romel", "C. L.", "" ], [ "Romie", "J. H.", "" ], [ "Rose", "K.", "" ], [ "Rosińska", "D.", "" ], [ "Rosofsky", "S. G.", "" ], [ "Ross", "M. P.", "" ], [ "Rowan", "S.", "" ], [ "Rüdiger", "A.", "" ], [ "Ruggi", "P.", "" ], [ "Rutins", "G.", "" ], [ "Ryan", "K.", "" ], [ "Sachdev", "S.", "" ], [ "Sadecki", "T.", "" ], [ "Sakellariadou", "M.", "" ], [ "Salconi", "L.", "" ], [ "Saleem", "M.", "" ], [ "Samajdar", "A.", "" ], [ "Sammut", "L.", "" ], [ "Sanchez", "E. J.", "" ], [ "Sanchez", "L. E.", "" ], [ "Sanchis-Gual", "N.", "" ], [ "Sandberg", "V.", "" ], [ "Sanders", "J. R.", "" ], [ "Santiago", "K. A.", "" ], [ "Sarin", "N.", "" ], [ "Sassolas", "B.", "" ], [ "Saulson", "P. R.", "" ], [ "Sauter", "O.", "" ], [ "Savage", "R. L.", "" ], [ "Schale", "P.", "" ], [ "Scheel", "M.", "" ], [ "Scheuer", "J.", "" ], [ "Schmidt", "P.", "" ], [ "Schnabel", "R.", "" ], [ "Schofield", "R. M. S.", "" ], [ "Schönbeck", "A.", "" ], [ "Schreiber", "E.", "" ], [ "Schulte", "B. W.", "" ], [ "Schutz", "B. F.", "" ], [ "Schwalbe", "S. G.", "" ], [ "Scott", "J.", "" ], [ "Scott", "S. M.", "" ], [ "Seidel", "E.", "" ], [ "Sellers", "D.", "" ], [ "Sengupta", "A. S.", "" ], [ "Sennett", "N.", "" ], [ "Sentenac", "D.", "" ], [ "Sequino", "V.", "" ], [ "Sergeev", "A.", "" ], [ "Setyawati", "Y.", "" ], [ "Shaddock", "D. A.", "" ], [ "Shaffer", "T.", "" ], [ "Shahriar", "M. S.", "" ], [ "Shaner", "M. B.", "" ], [ "Shao", "L.", "" ], [ "Sharma", "P.", "" ], [ "Shawhan", "P.", "" ], [ "Shen", "H.", "" ], [ "Shink", "R.", "" ], [ "Shoemaker", "D. H.", "" ], [ "Shoemaker", "D. M.", "" ], [ "ShyamSundar", "S.", "" ], [ "Siellez", "K.", "" ], [ "Sieniawska", "M.", "" ], [ "Sigg", "D.", "" ], [ "Silva", "A. D.", "" ], [ "Singer", "L. P.", "" ], [ "Singh", "N.", "" ], [ "Singhal", "A.", "" ], [ "Sintes", "A. M.", "" ], [ "Sitmukhambetov", "S.", "" ], [ "Skliris", "V.", "" ], [ "Slagmolen", "B. J. J.", "" ], [ "Slaven-Blair", "T. J.", "" ], [ "Smith", "J. R.", "" ], [ "Smith", "R. J. E.", "" ], [ "Somala", "S.", "" ], [ "Son", "E. J.", "" ], [ "Sorazu", "B.", "" ], [ "Sorrentino", "F.", "" ], [ "Souradeep", "T.", "" ], [ "Sowell", "E.", "" ], [ "Spencer", "A. P.", "" ], [ "Srivastava", "A. K.", "" ], [ "Srivastava", "V.", "" ], [ "Staats", "K.", "" ], [ "Stachie", "C.", "" ], [ "Standke", "M.", "" ], [ "Steer", "D. A.", "" ], [ "Steinke", "M.", "" ], [ "Steinlechner", "J.", "" ], [ "Steinlechner", "S.", "" ], [ "Steinmeyer", "D.", "" ], [ "Stevenson", "S. P.", "" ], [ "Stocks", "D.", "" ], [ "Stone", "R.", "" ], [ "Stops", "D. J.", "" ], [ "Strain", "K. A.", "" ], [ "Stratta", "G.", "" ], [ "Strigin", "S. E.", "" ], [ "Strunk", "A.", "" ], [ "Sturani", "R.", "" ], [ "Stuver", "A. L.", "" ], [ "Sudhir", "V.", "" ], [ "Summerscales", "T. Z.", "" ], [ "Sun", "L.", "" ], [ "Sunil", "S.", "" ], [ "Suresh", "J.", "" ], [ "Sutton", "P. J.", "" ], [ "Swinkels", "B. L.", "" ], [ "Szczepańczyk", "M. J.", "" ], [ "Tacca", "M.", "" ], [ "Tait", "S. C.", "" ], [ "Talbot", "C.", "" ], [ "Talukder", "D.", "" ], [ "Tanner", "D. B.", "" ], [ "Tápai", "M.", "" ], [ "Taracchini", "A.", "" ], [ "Tasson", "J. D.", "" ], [ "Taylor", "R.", "" ], [ "Thies", "F.", "" ], [ "Thomas", "M.", "" ], [ "Thomas", "P.", "" ], [ "Thondapu", "S. R.", "" ], [ "Thorne", "K. A.", "" ], [ "Thrane", "E.", "" ], [ "Tiwari", "Shubhanshu", "" ], [ "Tiwari", "Srishti", "" ], [ "Tiwari", "V.", "" ], [ "Toland", "K.", "" ], [ "Tonelli", "M.", "" ], [ "Tornasi", "Z.", "" ], [ "Torres-Forné", "A.", "" ], [ "Torrie", "C. I.", "" ], [ "Töyrä", "D.", "" ], [ "Travasso", "F.", "" ], [ "Traylor", "G.", "" ], [ "Tringali", "M. C.", "" ], [ "Trovato", "A.", "" ], [ "Trozzo", "L.", "" ], [ "Trudeau", "R.", "" ], [ "Tsang", "K. W.", "" ], [ "Tse", "M.", "" ], [ "Tso", "R.", "" ], [ "Tsukada", "L.", "" ], [ "Tsuna", "D.", "" ], [ "Tuyenbayev", "D.", "" ], [ "Ueno", "K.", "" ], [ "Ugolini", "D.", "" ], [ "Unnikrishnan", "C. S.", "" ], [ "Urban", "A. L.", "" ], [ "Usman", "S. A.", "" ], [ "Vahlbruch", "H.", "" ], [ "Vajente", "G.", "" ], [ "Valdes", "G.", "" ], [ "van Bakel", "N.", "" ], [ "van Beuzekom", "M.", "" ], [ "Brand", "J. F. J. van den", "" ], [ "Broeck", "C. Van Den", "" ], [ "Vander-Hyde", "D. C.", "" ], [ "van Heijningen", "J. V.", "" ], [ "van der Schaaf", "L.", "" ], [ "van Veggel", "A. A.", "" ], [ "Vardaro", "M.", "" ], [ "Varma", "V.", "" ], [ "Vass", "S.", "" ], [ "Vasúth", "M.", "" ], [ "Vecchio", "A.", "" ], [ "Vedovato", "G.", "" ], [ "Veitch", "J.", "" ], [ "Veitch", "P. J.", "" ], [ "Venkateswara", "K.", "" ], [ "Venugopalan", "G.", "" ], [ "Verkindt", "D.", "" ], [ "Vetrano", "F.", "" ], [ "Viceré", "A.", "" ], [ "Viets", "A. D.", "" ], [ "Vine", "D. J.", "" ], [ "Vinet", "J. -Y.", "" ], [ "Vitale", "S.", "" ], [ "Vo", "T.", "" ], [ "Vocca", "H.", "" ], [ "Vorvick", "C.", "" ], [ "Vyatchanin", "S. P.", "" ], [ "Wade", "A. R.", "" ], [ "Wade", "L. E.", "" ], [ "Wade", "M.", "" ], [ "Walet", "R.", "" ], [ "Walker", "M.", "" ], [ "Wallace", "L.", "" ], [ "Walsh", "S.", "" ], [ "Wang", "G.", "" ], [ "Wang", "H.", "" ], [ "Wang", "J. Z.", "" ], [ "Wang", "W. H.", "" ], [ "Wang", "Y. F.", "" ], [ "Ward", "R. L.", "" ], [ "Warden", "Z. A.", "" ], [ "Warner", "J.", "" ], [ "Was", "M.", "" ], [ "Watchi", "J.", "" ], [ "Weaver", "B.", "" ], [ "Wei", "L. -W.", "" ], [ "Weinert", "M.", "" ], [ "Weinstein", "A. J.", "" ], [ "Weiss", "R.", "" ], [ "Wellmann", "F.", "" ], [ "Wen", "L.", "" ], [ "Wessel", "E. K.", "" ], [ "Weßels", "P.", "" ], [ "Westhouse", "J. W.", "" ], [ "Wette", "K.", "" ], [ "Whelan", "J. T.", "" ], [ "Whiting", "B. F.", "" ], [ "Whittle", "C.", "" ], [ "Wilken", "D. M.", "" ], [ "Williams", "D.", "" ], [ "Williamson", "A. R.", "" ], [ "Willis", "J. L.", "" ], [ "Willke", "B.", "" ], [ "Wimmer", "M. H.", "" ], [ "Winkler", "W.", "" ], [ "Wipf", "C. C.", "" ], [ "Wittel", "H.", "" ], [ "Woan", "G.", "" ], [ "Woehler", "J.", "" ], [ "Wofford", "J. K.", "" ], [ "Worden", "J.", "" ], [ "Wright", "J. L.", "" ], [ "Wu", "D. S.", "" ], [ "Wysocki", "D. M.", "" ], [ "Xiao", "L.", "" ], [ "Xu", "R.", "" ], [ "Yamamoto", "H.", "" ], [ "Yancey", "C. C.", "" ], [ "Yang", "L.", "" ], [ "Yap", "M. J.", "" ], [ "Yazback", "M.", "" ], [ "Yeeles", "D. W.", "" ], [ "Yu", "Hang", "" ], [ "Yu", "Haocun", "" ], [ "Yuen", "S. H. R.", "" ], [ "Yvert", "M.", "" ], [ "Zadrożny", "A. K.", "" ], [ "Zanolin", "M.", "" ], [ "Zelenova", "T.", "" ], [ "Zendri", "J. -P.", "" ], [ "Zevin", "M.", "" ], [ "Zhang", "J.", "" ], [ "Zhang", "L.", "" ], [ "Zhang", "T.", "" ], [ "Zhao", "C.", "" ], [ "Zhou", "M.", "" ], [ "Zhou", "Z.", "" ], [ "Zhu", "X. J.", "" ], [ "Zucker", "M. E.", "" ], [ "Zweizig", "J.", "" ] ]
We perform an unmodeled search for persistent, directional gravitational wave (GW) sources using data from the first and second observing runs of Advanced LIGO. We do not find evidence for any GW signals. We place limits on the broadband GW flux emitted at 25~Hz from point sources with a power law spectrum at $F_{\alpha,\Theta} <(0.05-25)\times 10^{-8} ~{\rm erg\,cm^{-2}\,s^{-1}\,Hz^{-1}}$ and the (normalized) energy density spectrum in GWs at 25 Hz from extended sources at $\Omega_{\alpha}(\Theta) <(0.19-2.89)\times 10^{-8} ~{\rm sr^{-1}}$ where $\alpha$ is the spectral index of the energy density spectrum. These represent improvements of $2.5-3\times$ over previous limits. We also consider point sources emitting GWs at a single frequency, targeting the directions of Sco X-1, SN 1987A, and the Galactic Center. The best upper limits on the strain amplitude of a potential source in these three directions range from $h_0 < (3.6-4.7)\times 10^{-25}$, 1.5$\times$ better than previous limits set with the same analysis method. We also report on a marginally significant outlier at 36.06~Hz. This outlier is not consistent with a persistent gravitational-wave source as its significance diminishes when combining all of the available data.
2108.02738
Martina Muratore
Martina Muratore, Daniele Vetrugno, Stefano Vitale and Olaf Hartwig
Time Delay Interferometry combinations as instrument noise monitors for LISA
null
null
10.1103/PhysRevD.105.023009
null
gr-qc astro-ph.IM
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The LISA mission will likely be a signal dominated detector, such that one challenge is the separation of the different astrophysical sources, and to distinguish between them and the instrumental noise. One of the goals of LISA is to probe the early Universe by detecting stochastic GW backgrounds. As correlation with other detectors is not possible for LISA, discrimination of such a GW background from the instrumental noise requires a good estimate of the latter. To this purpose we have revisited Time Delay Interferometry (TDI) to look for new TDI signal combinations that fulfill the laser frequency noise suppression requirements. We illustrate that it is possible to do a linear combination of these TDI channels to find special null-combinations that suppress gravitational waves and mainly carry information about instrumental noise. We find that there exist many null-combinations that show different sensitivities to gravitational waves, some of which seem more suitable than the traditional T combination for estimating test-mass acceleration noise. In an idealised LISA configuration, they are all sensitive to a particular linear combination of the six test-masses acceleration, similar to a rigid rotation of the LISA triangle. In the following article, we illustrate what are the noise properties that can be extracted by monitoring these interferometry signals and discuss the implication of these findings for the detection of stochastic GW backgrounds.
[ { "created": "Thu, 5 Aug 2021 16:58:09 GMT", "version": "v1" }, { "created": "Sat, 13 Nov 2021 11:20:38 GMT", "version": "v2" }, { "created": "Thu, 13 Jan 2022 17:46:16 GMT", "version": "v3" } ]
2022-01-19
[ [ "Muratore", "Martina", "" ], [ "Vetrugno", "Daniele", "" ], [ "Vitale", "Stefano", "" ], [ "Hartwig", "Olaf", "" ] ]
The LISA mission will likely be a signal dominated detector, such that one challenge is the separation of the different astrophysical sources, and to distinguish between them and the instrumental noise. One of the goals of LISA is to probe the early Universe by detecting stochastic GW backgrounds. As correlation with other detectors is not possible for LISA, discrimination of such a GW background from the instrumental noise requires a good estimate of the latter. To this purpose we have revisited Time Delay Interferometry (TDI) to look for new TDI signal combinations that fulfill the laser frequency noise suppression requirements. We illustrate that it is possible to do a linear combination of these TDI channels to find special null-combinations that suppress gravitational waves and mainly carry information about instrumental noise. We find that there exist many null-combinations that show different sensitivities to gravitational waves, some of which seem more suitable than the traditional T combination for estimating test-mass acceleration noise. In an idealised LISA configuration, they are all sensitive to a particular linear combination of the six test-masses acceleration, similar to a rigid rotation of the LISA triangle. In the following article, we illustrate what are the noise properties that can be extracted by monitoring these interferometry signals and discuss the implication of these findings for the detection of stochastic GW backgrounds.
gr-qc/9609032
Carlo Baccigalupi
Luca Amendola, Carlo Baccigalupi, Franco Occhionero
Reconciling inflation with openness
4 pages, one postscript figure, to be published on Physical Review D PACS: 98.80. Cq
Phys.Rev. D54 (1996) 4760-4763
10.1103/PhysRevD.54.4760
null
gr-qc
null
It is already understood that the increasing observational evidence for an open Universe can be reconciled with inflation if our horizon is contained inside one single huge bubble nucleated during the inflationary phase transition. In this frame of ideas, we show here that the probability of living in a bubble with the right $\Omega_0$ (now the observations require $\Omega_0 \approx .2$) can be comparable with unity, rather than infinitesimally small. For this purpose we modify both quantitatively and qualitatively an intuitive toy model based upon fourth order gravity. As this scheme can be implemented in canonical General Relativity as well (although then the inflation driving potential must be designed entirely ad hoc), inferring from the observations that $\Omega_0 < 1$ not only does not conflict with the inflationary paradigm, but rather supports therein the occurrence of a primordial phase transition.
[ { "created": "Thu, 12 Sep 1996 16:02:47 GMT", "version": "v1" } ]
2015-06-25
[ [ "Amendola", "Luca", "" ], [ "Baccigalupi", "Carlo", "" ], [ "Occhionero", "Franco", "" ] ]
It is already understood that the increasing observational evidence for an open Universe can be reconciled with inflation if our horizon is contained inside one single huge bubble nucleated during the inflationary phase transition. In this frame of ideas, we show here that the probability of living in a bubble with the right $\Omega_0$ (now the observations require $\Omega_0 \approx .2$) can be comparable with unity, rather than infinitesimally small. For this purpose we modify both quantitatively and qualitatively an intuitive toy model based upon fourth order gravity. As this scheme can be implemented in canonical General Relativity as well (although then the inflation driving potential must be designed entirely ad hoc), inferring from the observations that $\Omega_0 < 1$ not only does not conflict with the inflationary paradigm, but rather supports therein the occurrence of a primordial phase transition.
2007.14794
Zixu Zhao
Zixu Zhao, Shuhang Zhang, Qiyuan Pan, Jiliang Jing
Estimation precision of parameter associated with Unruh-like effect
17 pages, 14 figures. arXiv admin note: substantial text overlap with arXiv:2007.13389
Nucl. Phys. B 967(2021)115408
10.1016/j.nuclphysb.2021.115408
null
gr-qc quant-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study the quantum Fisher information (QFI) of acceleration, in the open quantum systems, for a two-level atom with the circular motion coupled to a massless scalar field in the Minkowski vacuum without and with a reflecting boundary in the ultra-relativistic limit. As we amplify $a$, the saturation time decreases for $\theta\neq\pi$, but first increases and then decreases for $\theta=\pi$. Without a boundary, there exists a peak value of QFI with a certain time. The QFI varies with the initial state parameter $\theta$, and firstly takes peak value in the ground state of the atom. The variation of QFI with respect to $\theta$ gradually fades away with the evolution of time. With a boundary, the detection range of acceleration has been expanded. The QFI firstly takes the maximum in the excited state of the atom. In addition, we study the QFI of temperature for a static atom immersed in a thermal bath without and with a boundary. The relation between the saturation time and $T$ is similar to $a$. Without a boundary, the QFI of temperature is similar to that of acceleration. With a boundary, the QFI firstly takes peak value in the ground state of the atom, which is different from the behavior of acceleration. The results provide references for the detection of Unruh-like effect.
[ { "created": "Tue, 28 Jul 2020 03:05:52 GMT", "version": "v1" }, { "created": "Sun, 6 Sep 2020 09:49:30 GMT", "version": "v2" }, { "created": "Sun, 2 May 2021 13:55:42 GMT", "version": "v3" }, { "created": "Tue, 4 May 2021 00:37:34 GMT", "version": "v4" } ]
2021-05-05
[ [ "Zhao", "Zixu", "" ], [ "Zhang", "Shuhang", "" ], [ "Pan", "Qiyuan", "" ], [ "Jing", "Jiliang", "" ] ]
We study the quantum Fisher information (QFI) of acceleration, in the open quantum systems, for a two-level atom with the circular motion coupled to a massless scalar field in the Minkowski vacuum without and with a reflecting boundary in the ultra-relativistic limit. As we amplify $a$, the saturation time decreases for $\theta\neq\pi$, but first increases and then decreases for $\theta=\pi$. Without a boundary, there exists a peak value of QFI with a certain time. The QFI varies with the initial state parameter $\theta$, and firstly takes peak value in the ground state of the atom. The variation of QFI with respect to $\theta$ gradually fades away with the evolution of time. With a boundary, the detection range of acceleration has been expanded. The QFI firstly takes the maximum in the excited state of the atom. In addition, we study the QFI of temperature for a static atom immersed in a thermal bath without and with a boundary. The relation between the saturation time and $T$ is similar to $a$. Without a boundary, the QFI of temperature is similar to that of acceleration. With a boundary, the QFI firstly takes peak value in the ground state of the atom, which is different from the behavior of acceleration. The results provide references for the detection of Unruh-like effect.
2308.11040
Leda Gao
Leda Gao, Paul R. Anderson, Robert S. Link
Backreaction and order reduction in initially contracting models of the universe
58 pages, 19 figures
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The semiclassical backreaction equations are solved in closed Robertson-Walker spacetimes containing a positive cosmological constant and a conformally coupled massive scalar field. Renormalization of the stress-energy tensor results in higher derivative terms that can lead to solutions that vary on much shorter time scales than the solutions that would occur if the higher derivative terms were not present. These extra solutions can be eliminated through the use of order reduction. Four different methods of order reduction are investigated. These are first applied to the case when only conformally invariant fields, with and without classical radiation, are present. Then they are applied to the massive conformally coupled scalar field. The effects of different adiabatic vacuum states for the massive field are considered. It is found that if enough particles are produced, then the Universe collapses to a final singularity. Otherwise it undergoes a bounce, but at a smaller value of the scale factor (for the models considered) than occurs for the classical de Sitter solution. The stress-energy tensor incorporates both particle production and vacuum polarization effects. An analysis of the energy density of the massive field is done to determine when the contribution from the particles dominates.
[ { "created": "Mon, 21 Aug 2023 21:01:20 GMT", "version": "v1" } ]
2023-08-23
[ [ "Gao", "Leda", "" ], [ "Anderson", "Paul R.", "" ], [ "Link", "Robert S.", "" ] ]
The semiclassical backreaction equations are solved in closed Robertson-Walker spacetimes containing a positive cosmological constant and a conformally coupled massive scalar field. Renormalization of the stress-energy tensor results in higher derivative terms that can lead to solutions that vary on much shorter time scales than the solutions that would occur if the higher derivative terms were not present. These extra solutions can be eliminated through the use of order reduction. Four different methods of order reduction are investigated. These are first applied to the case when only conformally invariant fields, with and without classical radiation, are present. Then they are applied to the massive conformally coupled scalar field. The effects of different adiabatic vacuum states for the massive field are considered. It is found that if enough particles are produced, then the Universe collapses to a final singularity. Otherwise it undergoes a bounce, but at a smaller value of the scale factor (for the models considered) than occurs for the classical de Sitter solution. The stress-energy tensor incorporates both particle production and vacuum polarization effects. An analysis of the energy density of the massive field is done to determine when the contribution from the particles dominates.
gr-qc/0303081
Pierre Teyssandier
Pierre Teyssandier
Variation of the speed of light due to non-minimal coupling between electromagnetism and gravity
Invited lecture given at the Meeting on Electromagnetism organized by the Fondation Louis de Broglie in Peyresq, September 2-7, 2002; 13 pages. The new version gives the explicit definition of $\tilde{a}$ in Theorem 1
Annales Fond.Broglie 29 (2004) 173
null
null
gr-qc
null
We consider an Einstein-Maxwell action modified by the addition of three terms coupling the electromagnetic strength to the curvature tensor. The corresponding generalized Maxwell equations imply a variation of the speed of light in a vacuum. We determine this variation in Friedmann-Robertson-Walker spacetimes. We show that light propagates at a speed greater than $c$ when a simple condition is satisfied.
[ { "created": "Thu, 20 Mar 2003 17:23:37 GMT", "version": "v1" }, { "created": "Mon, 31 Mar 2003 09:52:02 GMT", "version": "v2" }, { "created": "Fri, 11 Apr 2003 17:23:05 GMT", "version": "v3" } ]
2007-05-23
[ [ "Teyssandier", "Pierre", "" ] ]
We consider an Einstein-Maxwell action modified by the addition of three terms coupling the electromagnetic strength to the curvature tensor. The corresponding generalized Maxwell equations imply a variation of the speed of light in a vacuum. We determine this variation in Friedmann-Robertson-Walker spacetimes. We show that light propagates at a speed greater than $c$ when a simple condition is satisfied.
2003.11169
Nikolaos Mavromatos
Nikolaos E. Mavromatos (King's College London)
Gravitational Anomalies in string-inspired Cosmologies: from Inflation to Axion Dark Matter?
16 pages latex, uses special macros. Invited talk in Corfu Summer Institute 2019 "School and Workshops on Elementary Particle Physics and Gravity" (CORFU2019), based on arXiv:1905.04685 [hep-th], arXiv:1907.04890 [hep-ph] and arXiv:2001.03465 [gr-qc], with which there may be partial text overlap
null
null
KCL-PH-TH/2020-13
gr-qc hep-ph hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this talk, I review briefly a scenario for the evolution of a string-inspired cosmological model, in which condensates of primordial gravitational waves (GW), formed at the very early eras after the Big Bang, are considered responsible for inducing inflation and then a smooth exit to a radiation dominated epoch. Primordial axion fields, that exist in the fundamental massless gravitational (bosonic) string multiplet, couple to the non-trivial GW-induced anomalies. As a result of this coupling, there exist axion background configurations which violate (spontaneously) Lorentz symmetry, and remain undiluted at the end of inflation. In models with heavy sterile right-handed neutrinos (RHN), such backgrounds are linked to novel (Lorentz and CPT Violating) mechanisms for the generation of matter-antimatter asymmetry in the Cosmos, via the asymmetric decays of the RHN to standard model particles and antiparticles. During the QCD epoch, the axions develop an instanton-induced mass and can, thus, play the r\^ole of Dark Matter (DM). The energy density of such a Universe, throughout its evolution, has the form of that of a "running vacuum model", that is, it can be expanded in power series of even powers of the Hubble parameter $H(t)$. The coefficients of those terms, though, are different for the various cosmological epochs. For the phenomenology of our model, which is consistent with the current cosmological data, and could also help in alleviating (some of) the tensions, it suffices to consider up to and including quartic powers of $H(t)$. In the early Universe phase, it is the $H^4(t)$ term, induced by the GW condensate of the gravitational anomaly, that drives inflation without the need for external inflaton fields.
[ { "created": "Wed, 25 Mar 2020 01:03:26 GMT", "version": "v1" } ]
2020-03-26
[ [ "Mavromatos", "Nikolaos E.", "", "King's College London" ] ]
In this talk, I review briefly a scenario for the evolution of a string-inspired cosmological model, in which condensates of primordial gravitational waves (GW), formed at the very early eras after the Big Bang, are considered responsible for inducing inflation and then a smooth exit to a radiation dominated epoch. Primordial axion fields, that exist in the fundamental massless gravitational (bosonic) string multiplet, couple to the non-trivial GW-induced anomalies. As a result of this coupling, there exist axion background configurations which violate (spontaneously) Lorentz symmetry, and remain undiluted at the end of inflation. In models with heavy sterile right-handed neutrinos (RHN), such backgrounds are linked to novel (Lorentz and CPT Violating) mechanisms for the generation of matter-antimatter asymmetry in the Cosmos, via the asymmetric decays of the RHN to standard model particles and antiparticles. During the QCD epoch, the axions develop an instanton-induced mass and can, thus, play the r\^ole of Dark Matter (DM). The energy density of such a Universe, throughout its evolution, has the form of that of a "running vacuum model", that is, it can be expanded in power series of even powers of the Hubble parameter $H(t)$. The coefficients of those terms, though, are different for the various cosmological epochs. For the phenomenology of our model, which is consistent with the current cosmological data, and could also help in alleviating (some of) the tensions, it suffices to consider up to and including quartic powers of $H(t)$. In the early Universe phase, it is the $H^4(t)$ term, induced by the GW condensate of the gravitational anomaly, that drives inflation without the need for external inflaton fields.
1201.4092
Pankaj Sharan
Pankaj Sharan
Covariant Extended Phase Space for Fields on Curved Background
19 pages. arXiv admin note: substantial text overlap with arXiv:1104.5095
null
null
null
gr-qc hep-th math-ph math.MP
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
It is shown that the nature of physical time requires the extended phase-space in mechanics to have a bundle structure with time as the 1-dimensional base manifold and the phase space as the fiber. This bundle picture of the extended phase space is then applied to fields in a covariant, `directly' Hamiltonian formalism. Variational principle in the covariant phase-space is discussed, Noether currents calculated for symmetry fields and a new bracket analogous to the Peierls bracket is defined.
[ { "created": "Thu, 19 Jan 2012 16:03:09 GMT", "version": "v1" } ]
2012-01-20
[ [ "Sharan", "Pankaj", "" ] ]
It is shown that the nature of physical time requires the extended phase-space in mechanics to have a bundle structure with time as the 1-dimensional base manifold and the phase space as the fiber. This bundle picture of the extended phase space is then applied to fields in a covariant, `directly' Hamiltonian formalism. Variational principle in the covariant phase-space is discussed, Noether currents calculated for symmetry fields and a new bracket analogous to the Peierls bracket is defined.
1009.1958
Francisco Lobo
Tiberiu Harko, Zolt\'an Kov\'acs, Francisco S.N. Lobo
Thin accretion disk signatures of slowly rotating black holes in Ho\v{r}ava gravity
12 pages, 15 figures. V2: 13 pages, clarifications and discussion added; version accepted for publication in Classical and Quantum Gravity
Class.Quant.Grav.28:165001,2011
10.1088/0264-9381/28/16/165001
null
gr-qc astro-ph.HE hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In the present work, we consider the possibility of observationally testing Ho\v{r}ava gravity by using the accretion disk properties around slowly rotating black holes of the Kehagias-Sfetsos solution in asymptotically flat spacetimes. The energy flux, temperature distribution, the emission spectrum as well as the energy conversion efficiency are obtained, and compared to the standard slowly rotating general relativistic Kerr solution. Comparing the mass accretion in a slowly rotating Kehagias-Sfetsos geometry in Ho\v{r}ava gravity with the one of a slowly rotating Kerr black hole, we verify that the intensity of the flux emerging from the disk surface is greater for the slowly rotating Kehagias-Sfetsos solution than for rotating black holes with the same geometrical mass and accretion rate. We also present the conversion efficiency of the accreting mass into radiation, and show that the rotating Kehagias-Sfetsos solution provides a much more efficient engine for the transformation of the accreting mass into radiation than the Kerr black holes. Thus, distinct signatures appear in the electromagnetic spectrum, leading to the possibility of directly testing Ho\v{r}ava gravity models by using astrophysical observations of the emission spectra from accretion disks.
[ { "created": "Fri, 10 Sep 2010 08:43:32 GMT", "version": "v1" }, { "created": "Wed, 22 Jun 2011 08:57:49 GMT", "version": "v2" } ]
2011-07-12
[ [ "Harko", "Tiberiu", "" ], [ "Kovács", "Zoltán", "" ], [ "Lobo", "Francisco S. N.", "" ] ]
In the present work, we consider the possibility of observationally testing Ho\v{r}ava gravity by using the accretion disk properties around slowly rotating black holes of the Kehagias-Sfetsos solution in asymptotically flat spacetimes. The energy flux, temperature distribution, the emission spectrum as well as the energy conversion efficiency are obtained, and compared to the standard slowly rotating general relativistic Kerr solution. Comparing the mass accretion in a slowly rotating Kehagias-Sfetsos geometry in Ho\v{r}ava gravity with the one of a slowly rotating Kerr black hole, we verify that the intensity of the flux emerging from the disk surface is greater for the slowly rotating Kehagias-Sfetsos solution than for rotating black holes with the same geometrical mass and accretion rate. We also present the conversion efficiency of the accreting mass into radiation, and show that the rotating Kehagias-Sfetsos solution provides a much more efficient engine for the transformation of the accreting mass into radiation than the Kerr black holes. Thus, distinct signatures appear in the electromagnetic spectrum, leading to the possibility of directly testing Ho\v{r}ava gravity models by using astrophysical observations of the emission spectra from accretion disks.
1903.05626
Badri Krishnan
Daniel Pook-Kolb, Ofek Birnholtz, Badri Krishnan and Erik Schnetter
The interior of a binary black hole merger
6 Pages, 7 Figures
Phys. Rev. Lett. 123, 171102 (2019)
10.1103/PhysRevLett.123.171102
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We find strong numerical evidence for a new phenomenon in a binary black hole spacetime, namely the merger of marginally outer trapped surfaces (MOTSs). By simulating the head-on collision of two non-spinning unequal mass black holes, we observe that the MOTS associated with the final black hole merges with the two initially disjoint surfaces corresponding to the two initial black holes. This yields a connected sequence of MOTSs interpolating between the initial and final state all the way through the non-linear binary black hole merger process. In addition, we show the existence of a MOTS with self-intersections formed immediately after the merger. This scenario now allows us to track physical quantities (such as mass, angular momentum, higher multipoles, and fluxes) across the merger, which can be potentially compared with the gravitational wave signal in the wave-zone, and with observations by gravitational wave detectors. This also suggests a possibility of proving the Penrose inequality mathematically for generic astrophysical binary back hole configurations.
[ { "created": "Wed, 13 Mar 2019 17:46:42 GMT", "version": "v1" }, { "created": "Wed, 26 Jun 2019 20:57:19 GMT", "version": "v2" }, { "created": "Tue, 22 Oct 2019 07:28:39 GMT", "version": "v3" } ]
2019-10-23
[ [ "Pook-Kolb", "Daniel", "" ], [ "Birnholtz", "Ofek", "" ], [ "Krishnan", "Badri", "" ], [ "Schnetter", "Erik", "" ] ]
We find strong numerical evidence for a new phenomenon in a binary black hole spacetime, namely the merger of marginally outer trapped surfaces (MOTSs). By simulating the head-on collision of two non-spinning unequal mass black holes, we observe that the MOTS associated with the final black hole merges with the two initially disjoint surfaces corresponding to the two initial black holes. This yields a connected sequence of MOTSs interpolating between the initial and final state all the way through the non-linear binary black hole merger process. In addition, we show the existence of a MOTS with self-intersections formed immediately after the merger. This scenario now allows us to track physical quantities (such as mass, angular momentum, higher multipoles, and fluxes) across the merger, which can be potentially compared with the gravitational wave signal in the wave-zone, and with observations by gravitational wave detectors. This also suggests a possibility of proving the Penrose inequality mathematically for generic astrophysical binary back hole configurations.
1008.0767
Mark Israelit
Mark Israelit (University of Haifa-Oranim)
A Weyl-Dirac Cosmological Model with DM and DE
25 pages. Submitted to GRG
Gen.Rel.Grav.43:751-775,2011
10.1007/s10714-010-1092-3
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In the Weyl-Dirac (W-D) framework a spatially closed cosmological model is considered. It is assumed that the space-time of the universe has a chaotic Weylian microstructure but is described on a large scale by Riemannian geometry. Locally fields of the Weyl connection vector act as creators of massive bosons having spin 1. It is suggested that these bosons, called weylons, provide most of the dark matter in the universe. At the beginning the universe is a spherically symmetric geometric entity without matter. Primary matter is created by Dirac's gauge function very close to the beginning. In the early epoch, when the temperature of the universe achieves its maximum, chaotically oriented Weyl vector fields being localized in micro-cells create weylons. In the dust dominated period Dirac's gauge function is giving rise to dark energy, the latter causing the cosmic acceleration at present. This oscillatory universe has an initial radius identical to the Plank length = 1.616 exp (-33) cm, at present the cosmic scale factor is 3.21 exp (28) cm, while its maximum value is 8.54 exp (28) cm. All forms of matter are created by geometrically based functions of the W-D theory.
[ { "created": "Wed, 4 Aug 2010 12:40:37 GMT", "version": "v1" } ]
2011-02-23
[ [ "Israelit", "Mark", "", "University of Haifa-Oranim" ] ]
In the Weyl-Dirac (W-D) framework a spatially closed cosmological model is considered. It is assumed that the space-time of the universe has a chaotic Weylian microstructure but is described on a large scale by Riemannian geometry. Locally fields of the Weyl connection vector act as creators of massive bosons having spin 1. It is suggested that these bosons, called weylons, provide most of the dark matter in the universe. At the beginning the universe is a spherically symmetric geometric entity without matter. Primary matter is created by Dirac's gauge function very close to the beginning. In the early epoch, when the temperature of the universe achieves its maximum, chaotically oriented Weyl vector fields being localized in micro-cells create weylons. In the dust dominated period Dirac's gauge function is giving rise to dark energy, the latter causing the cosmic acceleration at present. This oscillatory universe has an initial radius identical to the Plank length = 1.616 exp (-33) cm, at present the cosmic scale factor is 3.21 exp (28) cm, while its maximum value is 8.54 exp (28) cm. All forms of matter are created by geometrically based functions of the W-D theory.
gr-qc/0301121
V. Folomeev
V.N. Folomeev
Quantum Evolution of the Dilaton-Inflaton Model
11 pages, 4 figures
null
null
null
gr-qc
null
The quantum evolution of a model of the universe with account of two scalar fields ({\it dilaton} and {\it inflaton}) is considered. For this case, the closed and flat models has been examined. It is shown that in both cases the realization of conditions necessary for inflation is strongly depends on coupling constant for dilaton and inflaton fields.
[ { "created": "Thu, 30 Jan 2003 10:25:17 GMT", "version": "v1" } ]
2007-05-23
[ [ "Folomeev", "V. N.", "" ] ]
The quantum evolution of a model of the universe with account of two scalar fields ({\it dilaton} and {\it inflaton}) is considered. For this case, the closed and flat models has been examined. It is shown that in both cases the realization of conditions necessary for inflation is strongly depends on coupling constant for dilaton and inflaton fields.
gr-qc/9604020
Shingo Suzuki
Shingo Suzuki and Kei-ichi Maeda
Chaos in Schwarzschild Spacetime : The Motion of a Spinning Particle
18 pages, revtex, 9 figures(figures are available on request)
Phys.Rev. D55 (1997) 4848-4859
10.1103/PhysRevD.55.4848
WU-AP/59/96
gr-qc astro-ph
null
We study the motion of a spinning test particle in Schwarzschild spacetime, analyzing the Poincar\'e map and the Lyapunov exponent. We find chaotic behavior for a particle with spin higher than some critical value (e.g. $S_{cr} \sim 0.64 \mu M$ for the total angular momentum $J=4 \mu M$), where $\mu$ and $M$ are the masses of a particle and of a black hole, respectively. The inverse of the Lyapunov exponent in the most chaotic case is about three orbital periods, which suggests that chaos of a spinning particle may become important in some relativistic astrophysical phenomena. The ``effective potential" analysis enables us to classify the particle orbits into four types as follows. When the total angular momentum $J$ is large, some orbits are bounded and the ``effective potential"s are classified into two types: (B1) one saddle point (unstable circular orbit) and one minimal point (stable circular orbit) on the equatorial plane exist for small spin; and (B2) two saddle points bifurcate from the equatorial plane and one minimal point remains on the equatorial plane for large spin. When $J$ is small, no bound orbits exist and the potentials are classified into another two types: (U1) no extremal point is found for small spin; and (U2) one saddle point appears on the equatorial plane, which is unstable in the direction perpendicular to the equatorial plane, for large spin. The types (B1) and (U1) are the same as those for a spinless particle, but the potentials (B2) and (U2) are new types caused by spin-orbit coupling. The chaotic behavior is found only in the type (B2) potential. The ``heteroclinic orbit'', which could cause chaos, is also observed in type (B2).
[ { "created": "Tue, 9 Apr 1996 07:15:31 GMT", "version": "v1" } ]
2009-10-28
[ [ "Suzuki", "Shingo", "" ], [ "Maeda", "Kei-ichi", "" ] ]
We study the motion of a spinning test particle in Schwarzschild spacetime, analyzing the Poincar\'e map and the Lyapunov exponent. We find chaotic behavior for a particle with spin higher than some critical value (e.g. $S_{cr} \sim 0.64 \mu M$ for the total angular momentum $J=4 \mu M$), where $\mu$ and $M$ are the masses of a particle and of a black hole, respectively. The inverse of the Lyapunov exponent in the most chaotic case is about three orbital periods, which suggests that chaos of a spinning particle may become important in some relativistic astrophysical phenomena. The ``effective potential" analysis enables us to classify the particle orbits into four types as follows. When the total angular momentum $J$ is large, some orbits are bounded and the ``effective potential"s are classified into two types: (B1) one saddle point (unstable circular orbit) and one minimal point (stable circular orbit) on the equatorial plane exist for small spin; and (B2) two saddle points bifurcate from the equatorial plane and one minimal point remains on the equatorial plane for large spin. When $J$ is small, no bound orbits exist and the potentials are classified into another two types: (U1) no extremal point is found for small spin; and (U2) one saddle point appears on the equatorial plane, which is unstable in the direction perpendicular to the equatorial plane, for large spin. The types (B1) and (U1) are the same as those for a spinless particle, but the potentials (B2) and (U2) are new types caused by spin-orbit coupling. The chaotic behavior is found only in the type (B2) potential. The ``heteroclinic orbit'', which could cause chaos, is also observed in type (B2).
1703.08552
Fulvio Scaccabarozzi
Fulvio Scaccabarozzi and Jaiyul Yoo (Z\"urich)
Light-Cone Observables and Gauge-Invariance in the Geodesic Light-Cone Formalism
25 pages, no figures, published in JCAP
JCAP06(2017)007
10.1088/1475-7516/2017/06/007
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The remarkable properties of the geodesic light-cone (GLC) coordinates allow analytic expressions for the light-cone observables, providing a new non-perturbative way for calculating the effects of inhomogeneities in our Universe. However, the gauge-invariance of these expressions in the GLC formalism has not been shown explicitly. Here we provide this missing part of the GLC formalism by proving the gauge-invariance of the GLC expressions for the light-cone observables, such as the observed redshift, the luminosity distance, and the physical area and volume of the observed sources. Our study provides a new insight on the properties of the GLC coordinates and it complements the previous work by the GLC collaboration, leading to a comprehensive description of light propagation in the GLC representation.
[ { "created": "Fri, 24 Mar 2017 18:00:22 GMT", "version": "v1" }, { "created": "Tue, 6 Jun 2017 08:00:59 GMT", "version": "v2" } ]
2017-06-07
[ [ "Scaccabarozzi", "Fulvio", "", "Zürich" ], [ "Yoo", "Jaiyul", "", "Zürich" ] ]
The remarkable properties of the geodesic light-cone (GLC) coordinates allow analytic expressions for the light-cone observables, providing a new non-perturbative way for calculating the effects of inhomogeneities in our Universe. However, the gauge-invariance of these expressions in the GLC formalism has not been shown explicitly. Here we provide this missing part of the GLC formalism by proving the gauge-invariance of the GLC expressions for the light-cone observables, such as the observed redshift, the luminosity distance, and the physical area and volume of the observed sources. Our study provides a new insight on the properties of the GLC coordinates and it complements the previous work by the GLC collaboration, leading to a comprehensive description of light propagation in the GLC representation.
1001.2919
Etera R. Livine
Florian Girelli, Etera R. Livine
A Deformed Poincare Invariance for Group Field Theories
11 pages
Class. Quantum Grav. 27 (2010) 245018
10.1088/0264-9381/27/24/245018
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In the context of quantum gravity, group field theories are field theories that generate spinfoam amplitudes as Feynman diagrams. They can be understood as generalizations of the matrix models used for 2d quantum gravity. In particular Boulatov's theory reproduces the amplitudes of the Ponzano-Regge spinfoam model for 3d quantum gravity. Motivated by recent works on field theories on non-commutative flat spaces, we show that Boulatov's theory (and its colored version) is actually invariant under a global deformed Poincare symmetry. This allows to define a notion of flat/excited geometry states when considering scalar perturbations around classical solutions of the group field equations of motion. As a side-result, our analysis seems to point out that the notion of braiding of group field theories should be a key feature to study further in this context.
[ { "created": "Sun, 17 Jan 2010 19:24:29 GMT", "version": "v1" } ]
2015-05-18
[ [ "Girelli", "Florian", "" ], [ "Livine", "Etera R.", "" ] ]
In the context of quantum gravity, group field theories are field theories that generate spinfoam amplitudes as Feynman diagrams. They can be understood as generalizations of the matrix models used for 2d quantum gravity. In particular Boulatov's theory reproduces the amplitudes of the Ponzano-Regge spinfoam model for 3d quantum gravity. Motivated by recent works on field theories on non-commutative flat spaces, we show that Boulatov's theory (and its colored version) is actually invariant under a global deformed Poincare symmetry. This allows to define a notion of flat/excited geometry states when considering scalar perturbations around classical solutions of the group field equations of motion. As a side-result, our analysis seems to point out that the notion of braiding of group field theories should be a key feature to study further in this context.
1608.08951
Christopher Berry
Christopher P. L. Berry, Robert H. Cole, Priscilla Ca\~nizares and Jonathan R. Gair
Importance of transient resonances in extreme-mass-ratio inspirals
24 pages, 12 figures, 2 appendices; changes to match published version
Phys. Rev. D 94, 124042 (2016)
10.1103/PhysRevD.94.124042
null
gr-qc astro-ph.HE
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The inspiral of stellar-mass compact objects, like neutron stars or stellar-mass black holes, into supermassive black holes provides a wealth of information about the strong gravitational-field regime via the emission of gravitational waves. In order to detect and analyse these signals, accurate waveform templates which include the effects of the compact object's gravitational self-force are required. For computational efficiency, adiabatic templates are often used. These accurately reproduce orbit-averaged trajectories arising from the first-order self-force, but neglect other effects, such as transient resonances, where the radial and poloidal fundamental frequencies become commensurate. During such resonances the flux of gravitational waves can be diminished or enhanced, leading to a shift in the compact object's trajectory and the phase of the waveform. We present an evolution scheme for studying the effects of transient resonances and apply this to an astrophysically motivated population. We find that a large proportion of systems encounter a low-order resonance in the later stages of inspiral; however, the resulting effect on signal-to-noise recovery is small as a consequence of the low eccentricity of the inspirals. Neglecting the effects of transient resonances leads to a loss of 4% of detectable signals.
[ { "created": "Wed, 31 Aug 2016 17:19:16 GMT", "version": "v1" }, { "created": "Thu, 12 Jan 2017 11:09:44 GMT", "version": "v2" } ]
2017-01-13
[ [ "Berry", "Christopher P. L.", "" ], [ "Cole", "Robert H.", "" ], [ "Cañizares", "Priscilla", "" ], [ "Gair", "Jonathan R.", "" ] ]
The inspiral of stellar-mass compact objects, like neutron stars or stellar-mass black holes, into supermassive black holes provides a wealth of information about the strong gravitational-field regime via the emission of gravitational waves. In order to detect and analyse these signals, accurate waveform templates which include the effects of the compact object's gravitational self-force are required. For computational efficiency, adiabatic templates are often used. These accurately reproduce orbit-averaged trajectories arising from the first-order self-force, but neglect other effects, such as transient resonances, where the radial and poloidal fundamental frequencies become commensurate. During such resonances the flux of gravitational waves can be diminished or enhanced, leading to a shift in the compact object's trajectory and the phase of the waveform. We present an evolution scheme for studying the effects of transient resonances and apply this to an astrophysically motivated population. We find that a large proportion of systems encounter a low-order resonance in the later stages of inspiral; however, the resulting effect on signal-to-noise recovery is small as a consequence of the low eccentricity of the inspirals. Neglecting the effects of transient resonances leads to a loss of 4% of detectable signals.
2405.05970
Kwinten Fransen
Kwinten Fransen and Steven B. Giddings
Gravitational wave signatures of departures from classical black hole scattering
28 + 5 pages, 5 figures
null
null
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We initiate a general investigation into gravitational wave signatures of modifications to scattering of gravitational radiation from black holes. Such modifications may be present due to the quantum dynamics that makes black holes consistent with quantum mechanics, or in other models for departures from classical black hole behavior. We propose a parameterization of the corrections to scattering as a physically meaningful, model-independent, and practical bridge between theoretical and observational aspects of the problem; this parameterization can incorporate different models in the literature. We then describe how these corrections influence the gravitational wave signal, e.g. of a body orbiting a much more massive black hole. In particular, they generically change the rate of energy emission; this effect can be leveraged over many orbits of inspiral to enhance the sensitivity to small corrections, as has been noticed in simple models. We provide preliminary estimates of the sensitivity of future gravitational wave observations to these corrections, and outline further work to be done to connect both to a more fundamental theory of quantum black holes, and to realistic observational situations.
[ { "created": "Thu, 9 May 2024 17:59:56 GMT", "version": "v1" }, { "created": "Wed, 5 Jun 2024 18:00:00 GMT", "version": "v2" } ]
2024-06-07
[ [ "Fransen", "Kwinten", "" ], [ "Giddings", "Steven B.", "" ] ]
We initiate a general investigation into gravitational wave signatures of modifications to scattering of gravitational radiation from black holes. Such modifications may be present due to the quantum dynamics that makes black holes consistent with quantum mechanics, or in other models for departures from classical black hole behavior. We propose a parameterization of the corrections to scattering as a physically meaningful, model-independent, and practical bridge between theoretical and observational aspects of the problem; this parameterization can incorporate different models in the literature. We then describe how these corrections influence the gravitational wave signal, e.g. of a body orbiting a much more massive black hole. In particular, they generically change the rate of energy emission; this effect can be leveraged over many orbits of inspiral to enhance the sensitivity to small corrections, as has been noticed in simple models. We provide preliminary estimates of the sensitivity of future gravitational wave observations to these corrections, and outline further work to be done to connect both to a more fundamental theory of quantum black holes, and to realistic observational situations.
2310.00315
Deyou Chen
Yucheng He, Zeqiang Wang, Deyou Chen
Report on chaos bound outside Taub-NUT black holes
13 pages
Physics of the Dark Universe, 42 (2023) 101325
null
null
gr-qc hep-th
http://creativecommons.org/licenses/by/4.0/
Positions of a charged particle's equilibrium orbits and spatial regions where the chaos bound is violated are found through circular motions of the particle around charged Taub-NUT black holes. Lyapunov exponent is gotten by calculating eigenvalues of a Jacobian matrix in a phase space $(r,\pi_r)$. When the particle's charge is fixed, the positions of the equilibrium orbits gradually move away from the event horizons with the increase of the angular momentum.The result shows that the bound is violated in the near-horizon regions and at a certain distance from the horizons when the charge and NUT parameter are fixed. The spatial regions increase with the increase of the NUT parameter's value.
[ { "created": "Sat, 30 Sep 2023 09:10:33 GMT", "version": "v1" } ]
2023-10-03
[ [ "He", "Yucheng", "" ], [ "Wang", "Zeqiang", "" ], [ "Chen", "Deyou", "" ] ]
Positions of a charged particle's equilibrium orbits and spatial regions where the chaos bound is violated are found through circular motions of the particle around charged Taub-NUT black holes. Lyapunov exponent is gotten by calculating eigenvalues of a Jacobian matrix in a phase space $(r,\pi_r)$. When the particle's charge is fixed, the positions of the equilibrium orbits gradually move away from the event horizons with the increase of the angular momentum.The result shows that the bound is violated in the near-horizon regions and at a certain distance from the horizons when the charge and NUT parameter are fixed. The spatial regions increase with the increase of the NUT parameter's value.