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gr-qc/0512163
Daniel Hofmann
D. Hofmann, W. Kummer
IR Renormalisation of General Effective Actions and Hawking Flux in 2D Gravity Theories
25 pages
Eur.Phys.J.C48:291-301,2006
10.1140/epjc/s2006-02553-3
TUW-05-18
gr-qc
null
The infrared problem of the effective action in 2D is discussed in the framework of the Covariant Perturbation Theory. The divergences are regularised by a mass and the leading term is evaluated up to the third order of perturbation theory. A summation scheme is proposed which isolates the divergences from the finite part of the series and results in a single term. The latter turns out to be equivalent to the coupling to a certain classical external field. This suggests a renormalisation by factorisation.
[ { "created": "Thu, 29 Dec 2005 16:14:37 GMT", "version": "v1" } ]
2009-01-07
[ [ "Hofmann", "D.", "" ], [ "Kummer", "W.", "" ] ]
The infrared problem of the effective action in 2D is discussed in the framework of the Covariant Perturbation Theory. The divergences are regularised by a mass and the leading term is evaluated up to the third order of perturbation theory. A summation scheme is proposed which isolates the divergences from the finite part of the series and results in a single term. The latter turns out to be equivalent to the coupling to a certain classical external field. This suggests a renormalisation by factorisation.
0805.3978
W{\l}odzimierz Natorf
W. Natorf, J. Tafel
Horizons in Robinson-Trautman space-times
11p
Class.Quant.Grav.25:195012,2008
10.1088/0264-9381/25/19/195012
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The past quasi-local horizons in vacuum Robinson-Trautman spacetimes are described. The case of a null (non-expanding) horizon is discussed. It is shown that the only Robinson-Trautman space-time admitting such a horizon with sections diffeomorphic to S_2 is the Schwarzschild space-time. Weakening this condition leads to the horizons of the C-metric. Properties of the hypersurface r=2m for finite retarded time u are examined.
[ { "created": "Mon, 26 May 2008 14:58:58 GMT", "version": "v1" }, { "created": "Fri, 18 Jul 2008 13:29:39 GMT", "version": "v2" } ]
2008-11-26
[ [ "Natorf", "W.", "" ], [ "Tafel", "J.", "" ] ]
The past quasi-local horizons in vacuum Robinson-Trautman spacetimes are described. The case of a null (non-expanding) horizon is discussed. It is shown that the only Robinson-Trautman space-time admitting such a horizon with sections diffeomorphic to S_2 is the Schwarzschild space-time. Weakening this condition leads to the horizons of the C-metric. Properties of the hypersurface r=2m for finite retarded time u are examined.
1510.05515
Borja Reina
Borja Reina, Jos\'e M. M. Senovilla, Ra\"ul Vera
Junction conditions in quadratic gravity: thin shells and double layers
43 pages, 1 figure
null
10.1088/0264-9381/33/10/105008
null
gr-qc hep-th math-ph math.MP
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The junction conditions for the most general gravitational theory with a Lagrangian containing terms quadratic in the curvature are derived. We include the cases with a possible concentration of matter on the joining hypersurface -termed as thin shells, domain walls or braneworlds in the literature- as well as the proper matching conditions where only finite jumps of the energy-momentum tensor are allowed. In the latter case we prove that the matching conditions are more demanding than in General Relativity. In the former case, we show that generically the shells/domain walls are of a new kind because they possess, in addition to the standard energy-momentum tensor, a double layer energy-momentum contribution which actually induces an external energy flux vector and an external scalar pressure/tension on the shell. We prove that all these contributions are necessary to make the entire energy-momentum tensor divergence-free, and we present the field equations satisfied by these energy-momentum quantities. The consequences of all these results are briefly analyzed.
[ { "created": "Mon, 19 Oct 2015 15:09:12 GMT", "version": "v1" } ]
2016-04-27
[ [ "Reina", "Borja", "" ], [ "Senovilla", "José M. M.", "" ], [ "Vera", "Raül", "" ] ]
The junction conditions for the most general gravitational theory with a Lagrangian containing terms quadratic in the curvature are derived. We include the cases with a possible concentration of matter on the joining hypersurface -termed as thin shells, domain walls or braneworlds in the literature- as well as the proper matching conditions where only finite jumps of the energy-momentum tensor are allowed. In the latter case we prove that the matching conditions are more demanding than in General Relativity. In the former case, we show that generically the shells/domain walls are of a new kind because they possess, in addition to the standard energy-momentum tensor, a double layer energy-momentum contribution which actually induces an external energy flux vector and an external scalar pressure/tension on the shell. We prove that all these contributions are necessary to make the entire energy-momentum tensor divergence-free, and we present the field equations satisfied by these energy-momentum quantities. The consequences of all these results are briefly analyzed.
gr-qc/9807053
Wang Bin
Bin Wang, Ru-Keng Su and P.K.N.Yu
Quantum entropy of two-dimensional extreme charged dilaton black hole
Latex version, to be published on Phys.Lett.B
Phys.Lett. B438 (1998) 47-51
10.1016/S0370-2693(98)00947-2
null
gr-qc
null
By using Hawking's treatment as well as Zaslavskii's treatment respectively and the brick wall model, two different values of classical entropy and quantum entropy of scalar fields in the two-dimensional extreme charged dilaton black hole backgrounds have been obtained. A new divergent term emerges in the quantum entropy under the extreme limit for Zaslavskii's treatment and its connection with the phase transition has been addressed.
[ { "created": "Mon, 20 Jul 1998 14:09:02 GMT", "version": "v1" } ]
2009-10-31
[ [ "Wang", "Bin", "" ], [ "Su", "Ru-Keng", "" ], [ "Yu", "P. K. N.", "" ] ]
By using Hawking's treatment as well as Zaslavskii's treatment respectively and the brick wall model, two different values of classical entropy and quantum entropy of scalar fields in the two-dimensional extreme charged dilaton black hole backgrounds have been obtained. A new divergent term emerges in the quantum entropy under the extreme limit for Zaslavskii's treatment and its connection with the phase transition has been addressed.
gr-qc/9802046
David Hochberg
David Hochberg and Matt Visser
Dynamic wormholes, anti-trapped surfaces, and energy conditions
32 pages in plain LaTex, no figures. Additional text and references added
Phys.Rev.D58:044021,1998
10.1103/PhysRevD.58.044021
LAEFF-98/01
gr-qc
null
Adapting and extending a suggestion due to Page, we define a wormhole throat to be a marginally anti-trapped surface, that is, a closed two-dimensional spatial hypersurface such that one of the two future-directed null geodesic congruences orthogonal to it is just beginning to diverge. Typically a dynamic wormhole will possess two such throats, corresponding to the two orthogonal null geodesic congruences, and these two throats will not coincide, (though they do coalesce into a single throat in the static limit). The divergence property of the null geodesics at the marginally anti-trapped surface generalizes the ``flare-out'' condition for an arbitrary wormhole. We derive theorems regarding violations of the null energy condition (NEC) at and near these throats and find that, even for wormholes with arbitrary time-dependence, the violation of the NEC is a generic property of wormhole throats. We also discuss wormhole throats in the presence of fully antisymmetric torsion and find that the energy condition violations cannot be dumped into the torsion degrees of freedom. Finally by means of a concrete example we demonstrate that even temporary suspension of energy-condition violations is incompatible with the flare-out property of dynamic throats.
[ { "created": "Tue, 17 Feb 1998 18:02:23 GMT", "version": "v1" }, { "created": "Thu, 18 Jun 1998 09:38:03 GMT", "version": "v2" } ]
2008-11-26
[ [ "Hochberg", "David", "" ], [ "Visser", "Matt", "" ] ]
Adapting and extending a suggestion due to Page, we define a wormhole throat to be a marginally anti-trapped surface, that is, a closed two-dimensional spatial hypersurface such that one of the two future-directed null geodesic congruences orthogonal to it is just beginning to diverge. Typically a dynamic wormhole will possess two such throats, corresponding to the two orthogonal null geodesic congruences, and these two throats will not coincide, (though they do coalesce into a single throat in the static limit). The divergence property of the null geodesics at the marginally anti-trapped surface generalizes the ``flare-out'' condition for an arbitrary wormhole. We derive theorems regarding violations of the null energy condition (NEC) at and near these throats and find that, even for wormholes with arbitrary time-dependence, the violation of the NEC is a generic property of wormhole throats. We also discuss wormhole throats in the presence of fully antisymmetric torsion and find that the energy condition violations cannot be dumped into the torsion degrees of freedom. Finally by means of a concrete example we demonstrate that even temporary suspension of energy-condition violations is incompatible with the flare-out property of dynamic throats.
2011.06736
Zhen-Ming Xu
Zhen-Ming Xu
Analytic phase structures and thermodynamic curvature for the charged AdS black hole in alternative phase space
15 pages,1 figure, accepted by Frontiers of Physics
Frontiers of Physics 16(2) 24502 (2021)
10.1007/s11467-020-1038-5
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper, we visit the thermodynamic criticality and thermodynamic curvature of the charged AdS black hole in a new phase space. It is shown that when the square of the total charge of the charged black hole is considered as a thermodynamic quantity, the charged AdS black hole also admits an van der Waals-type critical behavior without the help of thermodynamic pressure and thermodynamic volume. Based on this, we study the fine phase structures of the charged AdS black hole with fixed AdS background in the new framework. On the one hand, we give the phase diagram structures of the charged AdS black hole accurately and analytically, which fills up the gap in dealing with the phase transition of the charged AdS black holes by taking the square of the charge as a thermodynamic quantity. On the other hand, we analyse the thermodynamic curvature of the black hole in two coordinate spaces. The thermodynamic curvatures obtained in two different coordinate spaces are equivalent to each other and are also positive. Based on an empirical conclusion under the framework of thermodynamic geometry, we speculate that when the square of charge is treated as an independent thermodynamic quantity, the charged AdS black hole is likely to present a repulsive between its molecules. More importantly, based on the thermodynamic curvature, we obtain an universal exponent at the critical point of phase transition.
[ { "created": "Fri, 13 Nov 2020 02:56:56 GMT", "version": "v1" } ]
2021-01-01
[ [ "Xu", "Zhen-Ming", "" ] ]
In this paper, we visit the thermodynamic criticality and thermodynamic curvature of the charged AdS black hole in a new phase space. It is shown that when the square of the total charge of the charged black hole is considered as a thermodynamic quantity, the charged AdS black hole also admits an van der Waals-type critical behavior without the help of thermodynamic pressure and thermodynamic volume. Based on this, we study the fine phase structures of the charged AdS black hole with fixed AdS background in the new framework. On the one hand, we give the phase diagram structures of the charged AdS black hole accurately and analytically, which fills up the gap in dealing with the phase transition of the charged AdS black holes by taking the square of the charge as a thermodynamic quantity. On the other hand, we analyse the thermodynamic curvature of the black hole in two coordinate spaces. The thermodynamic curvatures obtained in two different coordinate spaces are equivalent to each other and are also positive. Based on an empirical conclusion under the framework of thermodynamic geometry, we speculate that when the square of charge is treated as an independent thermodynamic quantity, the charged AdS black hole is likely to present a repulsive between its molecules. More importantly, based on the thermodynamic curvature, we obtain an universal exponent at the critical point of phase transition.
gr-qc/0101011
Yakov Itin
Shmuel Kaniel and Yakov Itin
On the derivation of the equations of motion in theories of gravity
17 pages
null
null
null
gr-qc math-ph math.MP
null
The equations of motion of massive particles in GR are completely determined by the field equation. We utilize the particular form of Einstein's field equation and propose for the $N$-body problem of the equations that are Lorentz invariant a novel algorithm for the derivation of the equations of motion from the field equations. It is: 1. Compute a static, spherically symmetric solution of the field equation. It will be singular at the origin. This will be taken to be the field generated by a single particle. 2. Move the solution on a trajectory $ {\psi(t)}$ and apply the instantaneous Lorentz transformation based on instantaneous velocity $\dot{\psi}(t)$. 3. Take, as first approximation, the field generated by $N$ particles to be the superposition of the fields generated by the single particles. 4. Compute the leading part of the equation. Hopefully, only terms that involves $\ddot{\psi}(t)$ will be dominant. This is the ``inertial'' part. 5. Compute by the quadratic part of the equation. This is the agent of the ``force''. 6. Equate for each singularity, the highest order terms of the singularities that came from the linear part and the quadratic parts, respectively. This is an equation between the inertial part and the force. The algorithm was applied to Einstein equations. The approximate evolution of scalar curvature lends, in turn, to an invariant scalar equation. The algorithm for it did produce Newton's law of gravitation. This is, also, the starting point for the embedding the trajectories in a common field.
[ { "created": "Tue, 2 Jan 2001 09:34:50 GMT", "version": "v1" } ]
2007-05-23
[ [ "Kaniel", "Shmuel", "" ], [ "Itin", "Yakov", "" ] ]
The equations of motion of massive particles in GR are completely determined by the field equation. We utilize the particular form of Einstein's field equation and propose for the $N$-body problem of the equations that are Lorentz invariant a novel algorithm for the derivation of the equations of motion from the field equations. It is: 1. Compute a static, spherically symmetric solution of the field equation. It will be singular at the origin. This will be taken to be the field generated by a single particle. 2. Move the solution on a trajectory $ {\psi(t)}$ and apply the instantaneous Lorentz transformation based on instantaneous velocity $\dot{\psi}(t)$. 3. Take, as first approximation, the field generated by $N$ particles to be the superposition of the fields generated by the single particles. 4. Compute the leading part of the equation. Hopefully, only terms that involves $\ddot{\psi}(t)$ will be dominant. This is the ``inertial'' part. 5. Compute by the quadratic part of the equation. This is the agent of the ``force''. 6. Equate for each singularity, the highest order terms of the singularities that came from the linear part and the quadratic parts, respectively. This is an equation between the inertial part and the force. The algorithm was applied to Einstein equations. The approximate evolution of scalar curvature lends, in turn, to an invariant scalar equation. The algorithm for it did produce Newton's law of gravitation. This is, also, the starting point for the embedding the trajectories in a common field.
2311.15784
Javlon Rayimbaev Javlon
Muhammad Ali Raza, Furkat Sarikulov, Javlon Rayimbaev, Muhammad Zubair, Bobomurat Ahmedov, Zdenek Stuchlik
Shadow of novel rotating black holes in GR coupled to nonlinear electrodynamics and constraints from EHT results
null
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study the optical properties of spacetime around a novel regular black hole (BH) in general relativity (GR) coupled to nonlinear electrodynamics (NED), which is asymptotically flat. First, we study the angular velocity and Lyapunov exponent in unstable photon circular orbits in the novel spherically symmetric BH spacetime. Later, the rotating regular BH solution is obtained using the Newmann-Janis algorithm, and the event horizon properties of the BH are determined. We analyze the effective potential for the circular motion of photons in the spacetime of the novel rotating BH. Also, we analyze the photon sphere around the novel BH and its shadow using celestial coordinates. We obtain that an increase of the BH spin and charge as well as NED field nonlinearity parameters causes an increase in the distortion parameter of the BH shadow, while, the area of the shadow and its oblateness decrease. Moreover, we also obtain the constraint values for the BH charge and the nonlinearity parameters using Event Horizon Telescope data from shadow sizes of supermassive BHs Sgr A* and M87*. Finally, the emission rate of BH evaporation through Hawking radiation is also studied.
[ { "created": "Mon, 27 Nov 2023 12:56:35 GMT", "version": "v1" }, { "created": "Fri, 1 Dec 2023 05:56:50 GMT", "version": "v2" } ]
2023-12-04
[ [ "Raza", "Muhammad Ali", "" ], [ "Sarikulov", "Furkat", "" ], [ "Rayimbaev", "Javlon", "" ], [ "Zubair", "Muhammad", "" ], [ "Ahmedov", "Bobomurat", "" ], [ "Stuchlik", "Zdenek", "" ] ]
We study the optical properties of spacetime around a novel regular black hole (BH) in general relativity (GR) coupled to nonlinear electrodynamics (NED), which is asymptotically flat. First, we study the angular velocity and Lyapunov exponent in unstable photon circular orbits in the novel spherically symmetric BH spacetime. Later, the rotating regular BH solution is obtained using the Newmann-Janis algorithm, and the event horizon properties of the BH are determined. We analyze the effective potential for the circular motion of photons in the spacetime of the novel rotating BH. Also, we analyze the photon sphere around the novel BH and its shadow using celestial coordinates. We obtain that an increase of the BH spin and charge as well as NED field nonlinearity parameters causes an increase in the distortion parameter of the BH shadow, while, the area of the shadow and its oblateness decrease. Moreover, we also obtain the constraint values for the BH charge and the nonlinearity parameters using Event Horizon Telescope data from shadow sizes of supermassive BHs Sgr A* and M87*. Finally, the emission rate of BH evaporation through Hawking radiation is also studied.
2110.01074
Carlos A. S. Almeida
F. C. E. Lima and C. A. S. Almeida
Compact-like vortices in isotropic curved spacetime
17 pages, 5 figures. To appear in Annals of Physics
null
10.1016/j.aop.2021.168648
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We introduced a generalized Maxwell-Higgs model in a $(3+1)$ isotropic spacetime, and we found their stationary solutions using the BPS approach in curved spacetime. In order to investigate the compact-like vortices, we assume a particular choice for the generalization term. The model is controlled by a potential driven by a single real parameter that can be used to change the vortex solutions profile as they approach their bound values. Resembling some flat spacetime vortex solutions, our model tends to compress the vortices when the parameter $l$ increases. Through numerical analysis, we also show the energy behavior and the magnetic field of the model.
[ { "created": "Sun, 3 Oct 2021 19:11:27 GMT", "version": "v1" } ]
2021-11-17
[ [ "Lima", "F. C. E.", "" ], [ "Almeida", "C. A. S.", "" ] ]
We introduced a generalized Maxwell-Higgs model in a $(3+1)$ isotropic spacetime, and we found their stationary solutions using the BPS approach in curved spacetime. In order to investigate the compact-like vortices, we assume a particular choice for the generalization term. The model is controlled by a potential driven by a single real parameter that can be used to change the vortex solutions profile as they approach their bound values. Resembling some flat spacetime vortex solutions, our model tends to compress the vortices when the parameter $l$ increases. Through numerical analysis, we also show the energy behavior and the magnetic field of the model.
0807.2507
Juan A. Valiente-Kroon
JA Valiente Kroon
Regularity conditions at spatial infinity revisited
41 pages
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The regular finite initial value problem at infinity is used to obtain regularity conditions on the freely specifiable parts of initial data for the vacuum Einstein equations with non-vanishing second fundamental form. These conditions ensure that the solutions of the propagation equations implied by the conformal Einstein equations at the cylinder at spatial infinity extend smoothly (and in fact analytically) through the critical sets where spatial infinity touches null infinity. In order to ease the analysis the conformal metric is assumed to be analytic, although the results presented here could be generalised to a setting where the conformal metric is only smooth. The analysis given here is a generalisation of the analysis on the regular finite initial value problem first carried out by Friedrich, for initial data sets with non-vanishing second fundamental form.
[ { "created": "Wed, 16 Jul 2008 07:29:36 GMT", "version": "v1" } ]
2008-07-17
[ [ "Kroon", "JA Valiente", "" ] ]
The regular finite initial value problem at infinity is used to obtain regularity conditions on the freely specifiable parts of initial data for the vacuum Einstein equations with non-vanishing second fundamental form. These conditions ensure that the solutions of the propagation equations implied by the conformal Einstein equations at the cylinder at spatial infinity extend smoothly (and in fact analytically) through the critical sets where spatial infinity touches null infinity. In order to ease the analysis the conformal metric is assumed to be analytic, although the results presented here could be generalised to a setting where the conformal metric is only smooth. The analysis given here is a generalisation of the analysis on the regular finite initial value problem first carried out by Friedrich, for initial data sets with non-vanishing second fundamental form.
gr-qc/0604046
Tae Hoon Lee
Tae Hoon Lee and Byung Joo Lee
Reply to "Comment on 'Scalar-tensor gravity coupled to a global monopole and flat rotation curves' "
4 pages, RevTeX4 file
Phys.Rev. D73 (2006) 128502
10.1103/PhysRevD.73.128502
null
gr-qc
null
In Brans-Dicke theory of gravity we explain how the extra constant value in the formula for rotation velocities of stars in a galactic halo can be obtained due to the global monopole field. We argue on a few points of the preceding Comment and discuss improvement of our model.
[ { "created": "Mon, 10 Apr 2006 13:19:21 GMT", "version": "v1" } ]
2009-11-11
[ [ "Lee", "Tae Hoon", "" ], [ "Lee", "Byung Joo", "" ] ]
In Brans-Dicke theory of gravity we explain how the extra constant value in the formula for rotation velocities of stars in a galactic halo can be obtained due to the global monopole field. We argue on a few points of the preceding Comment and discuss improvement of our model.
1712.06517
Bob Holdom
Randy S. Conklin, Bob Holdom and Jing Ren
Gravitational wave echoes through new windows
37 pages, 19 figures, matches version to be published in PRD
Phys. Rev. D 98, 044021 (2018)
10.1103/PhysRevD.98.044021
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
There has been a striking realization that physics resolving the black hole information paradox could imply postmerger gravitational wave echoes. We here report on evidence for echoes from the LIGO compact binary merger events, GW151226, GW170104, GW170608, GW170814, as well as the neutron star merger GW170817. There is a signal for each event with a $p$-value of order 1% or sometimes significantly less. Our study begins with the comparison of echoes from a variety of horizonless exotic compact objects. Next we investigate the effects of spin. The identification of the more generic features of echoes then leads to the development of relatively simple windowing methods, in both time and frequency space, to extract a signal from noise. The time delay between echoes is inversely related to the spacing between the spectral resonances, and it is advantageous to look directly for this resonance structure. We find time delays for the first four events that are consistent with a simple model that accounts for mass and spin of the final object, while for the neutron star merger the final mass and spin are constrained.
[ { "created": "Mon, 18 Dec 2017 16:52:44 GMT", "version": "v1" }, { "created": "Mon, 29 Jan 2018 17:46:00 GMT", "version": "v2" }, { "created": "Wed, 30 May 2018 18:27:03 GMT", "version": "v3" }, { "created": "Mon, 6 Aug 2018 00:31:02 GMT", "version": "v4" } ]
2018-08-23
[ [ "Conklin", "Randy S.", "" ], [ "Holdom", "Bob", "" ], [ "Ren", "Jing", "" ] ]
There has been a striking realization that physics resolving the black hole information paradox could imply postmerger gravitational wave echoes. We here report on evidence for echoes from the LIGO compact binary merger events, GW151226, GW170104, GW170608, GW170814, as well as the neutron star merger GW170817. There is a signal for each event with a $p$-value of order 1% or sometimes significantly less. Our study begins with the comparison of echoes from a variety of horizonless exotic compact objects. Next we investigate the effects of spin. The identification of the more generic features of echoes then leads to the development of relatively simple windowing methods, in both time and frequency space, to extract a signal from noise. The time delay between echoes is inversely related to the spacing between the spectral resonances, and it is advantageous to look directly for this resonance structure. We find time delays for the first four events that are consistent with a simple model that accounts for mass and spin of the final object, while for the neutron star merger the final mass and spin are constrained.
1911.06908
Daniela Doneva
Daniela D. Doneva, Stoytcho S. Yazadjiev
Topological neutron stars in tensor-multi-scalar theories of gravity
6 pages, 6 figures
Phys. Rev. D 101, 064072 (2020)
10.1103/PhysRevD.101.064072
null
gr-qc astro-ph.HE
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In the present paper we demonstrate that there exists a new type of neutron stars in the tensor-multi-scalar theories of gravity. We call this new type of neutron stars topological neutron stars. In addition to the standard characteristics of the usual neutron stars the topological neutron stars are also characterized by a topological charge. We numerical construct explicit examples of topological neutron stars in tensor-multi-scalar theories whose target space is $\mathbb{S}^3$. Besides the topological charge the topological neutron stars also exhibit other attractive features which can place them among the realistic compact objects that could exist in Nature. For example they possess zero scalar charge and thus evades the strong binary pulsar constraints on the dipole scalar radiation.
[ { "created": "Fri, 15 Nov 2019 23:22:30 GMT", "version": "v1" } ]
2020-04-08
[ [ "Doneva", "Daniela D.", "" ], [ "Yazadjiev", "Stoytcho S.", "" ] ]
In the present paper we demonstrate that there exists a new type of neutron stars in the tensor-multi-scalar theories of gravity. We call this new type of neutron stars topological neutron stars. In addition to the standard characteristics of the usual neutron stars the topological neutron stars are also characterized by a topological charge. We numerical construct explicit examples of topological neutron stars in tensor-multi-scalar theories whose target space is $\mathbb{S}^3$. Besides the topological charge the topological neutron stars also exhibit other attractive features which can place them among the realistic compact objects that could exist in Nature. For example they possess zero scalar charge and thus evades the strong binary pulsar constraints on the dipole scalar radiation.
1408.5669
Dirk Puetzfeld
Dirk Puetzfeld, Yuri N. Obukhov
Equations of motion in metric-affine gravity: A covariant unified framework
13 pages, RevTex format. Dedicated to Friedrich W. Hehl on the occasion of his birthday
Phys. Rev. D 90 (2014) 085034
10.1103/PhysRevD.90.084034
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We derive the equations of motion of extended deformable bodies in metric-affine gravity. The conservation laws which follow from the invariance of the action under the general coordinate transformations are used as a starting point for the discussion of the dynamics of extended deformable test bodies. By means of a covariant approach, based on Synge's world function, we obtain the master equation of motion for an arbitrary system of coupled conserved currents. This unified framework is then applied to metric-affine gravity. We confirm and extend earlier findings; in particular, we once again demonstrate that it is only possible to detect the post-Riemannian spacetime geometry by ordinary (non-microstructured) test bodies if gravity is nonminimally coupled to matter.
[ { "created": "Mon, 25 Aug 2014 06:44:57 GMT", "version": "v1" }, { "created": "Tue, 21 Oct 2014 08:41:37 GMT", "version": "v2" } ]
2014-10-22
[ [ "Puetzfeld", "Dirk", "" ], [ "Obukhov", "Yuri N.", "" ] ]
We derive the equations of motion of extended deformable bodies in metric-affine gravity. The conservation laws which follow from the invariance of the action under the general coordinate transformations are used as a starting point for the discussion of the dynamics of extended deformable test bodies. By means of a covariant approach, based on Synge's world function, we obtain the master equation of motion for an arbitrary system of coupled conserved currents. This unified framework is then applied to metric-affine gravity. We confirm and extend earlier findings; in particular, we once again demonstrate that it is only possible to detect the post-Riemannian spacetime geometry by ordinary (non-microstructured) test bodies if gravity is nonminimally coupled to matter.
0710.5169
Keisuke Taniguchi
Keisuke Taniguchi, Thomas W. Baumgarte, Joshua A. Faber, and Stuart L. Shapiro
Relativistic black hole-neutron star binaries in quasiequilibrium: effects of the black hole excision boundary condition
Minor corrections, Fig.8 revised, 15 pages, 15 figures, published in Phys. Rev. D
Phys.Rev.D77:044003,2008
10.1103/PhysRevD.77.044003
null
gr-qc astro-ph
null
We construct new models of black hole-neutron star binaries in quasiequilibrium circular orbits by solving Einstein's constraint equations in the conformal thin-sandwich decomposition together with the relativistic equations of hydrostationary equilibrium. We adopt maximal slicing, assume spatial conformal flatness, and impose equilibrium boundary conditions on an excision surface (i.e., the apparent horizon) to model the black hole. In our previous treatment we adopted a "leading-order" approximation for a parameter related to the black-hole spin in these boundary conditions to construct approximately nonspinning black holes. Here we improve on the models by computing the black hole's quasilocal spin angular momentum and setting it to zero. As before, we adopt a polytropic equation of state with adiabatic index Gamma=2 and assume the neutron star to be irrotational. In addition to recomputing several sequences for comparison with our earlier results, we study a wider range of neutron star masses and binary mass ratios. To locate the innermost stable circular orbit we search for turning points along both the binding energy and total angular momentum curves for these sequences. Unlike for our previous approximate boundary condition, these two minima now coincide. We also identify the formation of cusps on the neutron star surface, indicating the onset of tidal disruption. Comparing these two critical binary separations for different mass ratios and neutron star compactions we distinguish those regions that will lead to a tidal disruption of the neutron star from those that will result in the plunge into the black hole of a neutron star more or less intact, albeit distorted by tidal forces.
[ { "created": "Fri, 26 Oct 2007 20:00:06 GMT", "version": "v1" }, { "created": "Wed, 12 Dec 2007 16:50:53 GMT", "version": "v2" }, { "created": "Fri, 1 Feb 2008 21:06:05 GMT", "version": "v3" } ]
2008-11-26
[ [ "Taniguchi", "Keisuke", "" ], [ "Baumgarte", "Thomas W.", "" ], [ "Faber", "Joshua A.", "" ], [ "Shapiro", "Stuart L.", "" ] ]
We construct new models of black hole-neutron star binaries in quasiequilibrium circular orbits by solving Einstein's constraint equations in the conformal thin-sandwich decomposition together with the relativistic equations of hydrostationary equilibrium. We adopt maximal slicing, assume spatial conformal flatness, and impose equilibrium boundary conditions on an excision surface (i.e., the apparent horizon) to model the black hole. In our previous treatment we adopted a "leading-order" approximation for a parameter related to the black-hole spin in these boundary conditions to construct approximately nonspinning black holes. Here we improve on the models by computing the black hole's quasilocal spin angular momentum and setting it to zero. As before, we adopt a polytropic equation of state with adiabatic index Gamma=2 and assume the neutron star to be irrotational. In addition to recomputing several sequences for comparison with our earlier results, we study a wider range of neutron star masses and binary mass ratios. To locate the innermost stable circular orbit we search for turning points along both the binding energy and total angular momentum curves for these sequences. Unlike for our previous approximate boundary condition, these two minima now coincide. We also identify the formation of cusps on the neutron star surface, indicating the onset of tidal disruption. Comparing these two critical binary separations for different mass ratios and neutron star compactions we distinguish those regions that will lead to a tidal disruption of the neutron star from those that will result in the plunge into the black hole of a neutron star more or less intact, albeit distorted by tidal forces.
1704.06077
Albert V. Minkevich
A.V. Minkevich
Vacuum torsion and regular accelerating Universe without dark matter
null
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The simplest gauge gravitation theory in Riemann-Cartan space-time leading to the solution of the problem of cosmological singularity and dark energy problem is investigated with purpose to solve the dark matter problem. It is shown that the interaction of the vacuum torsion field with proper angular moments of gravitating objects can lead to appearance at astrophysical scale (galaxies, galactic clusters) additional force of gravitational attraction, which in the frame of standard theory is connected with dark matter.
[ { "created": "Thu, 20 Apr 2017 10:15:25 GMT", "version": "v1" }, { "created": "Mon, 8 May 2017 08:21:49 GMT", "version": "v2" } ]
2017-05-09
[ [ "Minkevich", "A. V.", "" ] ]
The simplest gauge gravitation theory in Riemann-Cartan space-time leading to the solution of the problem of cosmological singularity and dark energy problem is investigated with purpose to solve the dark matter problem. It is shown that the interaction of the vacuum torsion field with proper angular moments of gravitating objects can lead to appearance at astrophysical scale (galaxies, galactic clusters) additional force of gravitational attraction, which in the frame of standard theory is connected with dark matter.
1810.11621
Przemyslaw Malkiewicz
Przemys{\l}aw Ma{\l}kiewicz
Hamiltonian formalism and gauge-fixing conditions for cosmological perturbation theory
38 pages, 1 figure, includes a discussion of the relation between the Dirac observables and the gauge-invariant variables such as the Bardeen potentials or the Mukhanov-Sasaki variable
Class. Quantum Grav. 36 (2019) 215003
10.1088/1361-6382/ab45aa
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We apply the Dirac procedure for constrained systems to the Arnowitt-Deser-Misner formalism linearized around the Friedmann-Lemaitre universe. We explain and employ some basic concepts such as Dirac observables, Dirac brackets, gauge-fixing conditions, reduced phase space, physical Hamiltonian and physical dynamics. In particular, we elaborate on the key concept which is the canonical isomorphism between different gauge-fixing surfaces. We apply our formalism to describe the reduced phase space of cosmological perturbations in some popular in the literature gauges. Our formalism is first developed for the universe with a single fluid and then extended to the multi-fluid case. The obtained results are a starting point for complete quantization of the cosmological perturbations and the cosmological background. Our approach may be used in future to derive the reduced phase space of higher order perturbations and in more generic cosmological spacetimes.
[ { "created": "Sat, 27 Oct 2018 08:57:35 GMT", "version": "v1" }, { "created": "Mon, 3 Dec 2018 09:36:48 GMT", "version": "v2" }, { "created": "Tue, 29 Oct 2019 09:09:12 GMT", "version": "v3" } ]
2019-10-30
[ [ "Małkiewicz", "Przemysław", "" ] ]
We apply the Dirac procedure for constrained systems to the Arnowitt-Deser-Misner formalism linearized around the Friedmann-Lemaitre universe. We explain and employ some basic concepts such as Dirac observables, Dirac brackets, gauge-fixing conditions, reduced phase space, physical Hamiltonian and physical dynamics. In particular, we elaborate on the key concept which is the canonical isomorphism between different gauge-fixing surfaces. We apply our formalism to describe the reduced phase space of cosmological perturbations in some popular in the literature gauges. Our formalism is first developed for the universe with a single fluid and then extended to the multi-fluid case. The obtained results are a starting point for complete quantization of the cosmological perturbations and the cosmological background. Our approach may be used in future to derive the reduced phase space of higher order perturbations and in more generic cosmological spacetimes.
gr-qc/0502122
Dimitrios Giannios
Dimitrios Giannios
Spherically symmetric, static spacetimes in a tensor-vector-scalar theory
12 pages, accepted for publication in Phys. Rev. D
Phys.Rev. D71 (2005) 103511
10.1103/PhysRevD.71.103511
null
gr-qc astro-ph
null
Recently, a relativistic gravitation theory has been proposed [J. D. Bekenstein, Phys. Rev. D {\bf 70}, 083509 (2004)] that gives the Modified Newtonian Dynamics (or MOND) in the weak acceleration regime. The theory is based on three dynamic gravitational fields and succeeds in explaining a large part of extragalactic and gravitational lensing phenomenology without invoking dark matter. In this work we consider the strong gravity regime of TeVeS. We study spherically symmetric, static and vacuum spacetimes relevant for a non-rotating black hole or the exterior of a star. Two branches of solutions are identified: in the first the vector field is aligned with the time direction while in the second the vector field has a non-vanishing radial component. We show that in the first branch of solutions the \beta and \gamma PPN coefficients in TeVeS are identical to these of general relativity (GR) while in the second the \beta PPN coefficient differs from unity violating observational determinations of it (for the choice of the free function $F$ of the theory made in Bekenstein's paper). For the first branch of solutions, we derive analytic expressions for the physical metric and discuss their implications. Applying these solutions to the case of black holes, it is shown that they violate causality (since they allow for superluminal propagation of metric, vector and scalar waves) in the vicinity of the event horizon and/or that they are characterized by negative energy density carried by the fields.
[ { "created": "Mon, 28 Feb 2005 19:09:52 GMT", "version": "v1" }, { "created": "Wed, 27 Apr 2005 13:58:24 GMT", "version": "v2" } ]
2016-08-31
[ [ "Giannios", "Dimitrios", "" ] ]
Recently, a relativistic gravitation theory has been proposed [J. D. Bekenstein, Phys. Rev. D {\bf 70}, 083509 (2004)] that gives the Modified Newtonian Dynamics (or MOND) in the weak acceleration regime. The theory is based on three dynamic gravitational fields and succeeds in explaining a large part of extragalactic and gravitational lensing phenomenology without invoking dark matter. In this work we consider the strong gravity regime of TeVeS. We study spherically symmetric, static and vacuum spacetimes relevant for a non-rotating black hole or the exterior of a star. Two branches of solutions are identified: in the first the vector field is aligned with the time direction while in the second the vector field has a non-vanishing radial component. We show that in the first branch of solutions the \beta and \gamma PPN coefficients in TeVeS are identical to these of general relativity (GR) while in the second the \beta PPN coefficient differs from unity violating observational determinations of it (for the choice of the free function $F$ of the theory made in Bekenstein's paper). For the first branch of solutions, we derive analytic expressions for the physical metric and discuss their implications. Applying these solutions to the case of black holes, it is shown that they violate causality (since they allow for superluminal propagation of metric, vector and scalar waves) in the vicinity of the event horizon and/or that they are characterized by negative energy density carried by the fields.
0810.1083
Luis Herrera
L. Herrera, N.O. Santos, A. Wang
Shearing Expansion-free Spherical Anisotropic Fluid Evolution
24 Latex pages. To appear in Phys. Rev. D
Phys.Rev.D78:084026,2008
10.1103/PhysRevD.78.084026
null
gr-qc astro-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Spherically symmetric expansionfree distributions are systematically studied. The whole set of field equations and junction conditions are presented for a general distribution of dissipative anisotropic fluid (principal stresses unequal), and the expansionfree condition is integrated. In order to understand the physical meaning of expansionfree motion, two different definitions for the radial velocity of a fluid element are discussed. It is shown that the appearance of a cavity is inevitable in the expansionfree evolution. The nondissipative case is considered in detail and the Skripkin model is recovered.
[ { "created": "Tue, 7 Oct 2008 01:57:32 GMT", "version": "v1" } ]
2008-11-26
[ [ "Herrera", "L.", "" ], [ "Santos", "N. O.", "" ], [ "Wang", "A.", "" ] ]
Spherically symmetric expansionfree distributions are systematically studied. The whole set of field equations and junction conditions are presented for a general distribution of dissipative anisotropic fluid (principal stresses unequal), and the expansionfree condition is integrated. In order to understand the physical meaning of expansionfree motion, two different definitions for the radial velocity of a fluid element are discussed. It is shown that the appearance of a cavity is inevitable in the expansionfree evolution. The nondissipative case is considered in detail and the Skripkin model is recovered.
1103.2723
Daniele Pranzetti
Jonathan Engle, Karim Noui, Alejandro Perez, Daniele Pranzetti
The SU(2) Black Hole entropy revisited
31 pages, 8 figures
JHEP 1105 (2011) 016
10.1007/JHEP05(2011)016
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study the state-counting problem that arises in the SU(2) black hole entropy calculation in loop quantum gravity. More precisely, we compute the leading term and the logarithmic correction of both the spherically symmetric and the distorted SU(2) black holes. Contrary to what has been done in previous works, we have to take into account "quantum corrections" in our framework in the sense that the level k of the Chern-Simons theory which describes the black hole is finite and not sent to infinity. Therefore, the new results presented here allow for the computation of the entropy in models where the quantum group corrections are important.
[ { "created": "Mon, 14 Mar 2011 17:37:24 GMT", "version": "v1" } ]
2012-08-15
[ [ "Engle", "Jonathan", "" ], [ "Noui", "Karim", "" ], [ "Perez", "Alejandro", "" ], [ "Pranzetti", "Daniele", "" ] ]
We study the state-counting problem that arises in the SU(2) black hole entropy calculation in loop quantum gravity. More precisely, we compute the leading term and the logarithmic correction of both the spherically symmetric and the distorted SU(2) black holes. Contrary to what has been done in previous works, we have to take into account "quantum corrections" in our framework in the sense that the level k of the Chern-Simons theory which describes the black hole is finite and not sent to infinity. Therefore, the new results presented here allow for the computation of the entropy in models where the quantum group corrections are important.
0910.0325
Ming Lei Tong
Ming-Lei Tong, Yang Zhang
Relic Gravitational Waves with A Running Spectral Index and Its Constraints at High Frequencies
17 pages, 10 figures, Accepted by PRD
Phys.Rev.D80:084022,2009
10.1103/PhysRevD.80.084022
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study the impact of a running index $\alpha_t$ on the spectrum of relic gravitational waves (RGWs) over the whole range of frequency $(10^{-18}\sim 10^{10})$ Hz and reveal its implications in RGWs detections and in cosmology. Analytical calculations show that, although the spectrum of RGWs on low frequencies is less affected by $\alpha_t\ne 0$, but, on high frequencies, the spectrum is modified substantially. Investigations are made toward potential detections of the $\alpha_t$-modified RGWs for several kinds of current and planned detectors. The Advanced LIGO will likely be able to detect RGWs with $\alpha_t\ge 0$ for inflationary models with the inflation index $\beta=-1.956$ and the tensor-scalar ratio $r= 0.55$. The future LISA can detect RGWs for a much broader range of ($\alpha_t$, $\beta$, $r$), and will have a better chance to break a degeneracy between them. Constraints on $\alpha_t$ are estimated from several detections and cosmological observations. Among them, the most stringent one is from the bound of the Big Bang nucleosynthesis (BBN), and requires $\alpha_t < 0.008$ rather conservatively for any reasonable ($\beta$, $r$), preferring a nearly power-law spectrum of RGWs. In light of this result, one would expect the scalar running index $\alpha_s$ to be of the same magnitude as $\alpha_t$, if both RGWs and scalar perturbations are generated by the same scalar inflation.
[ { "created": "Fri, 2 Oct 2009 05:03:41 GMT", "version": "v1" } ]
2009-10-29
[ [ "Tong", "Ming-Lei", "" ], [ "Zhang", "Yang", "" ] ]
We study the impact of a running index $\alpha_t$ on the spectrum of relic gravitational waves (RGWs) over the whole range of frequency $(10^{-18}\sim 10^{10})$ Hz and reveal its implications in RGWs detections and in cosmology. Analytical calculations show that, although the spectrum of RGWs on low frequencies is less affected by $\alpha_t\ne 0$, but, on high frequencies, the spectrum is modified substantially. Investigations are made toward potential detections of the $\alpha_t$-modified RGWs for several kinds of current and planned detectors. The Advanced LIGO will likely be able to detect RGWs with $\alpha_t\ge 0$ for inflationary models with the inflation index $\beta=-1.956$ and the tensor-scalar ratio $r= 0.55$. The future LISA can detect RGWs for a much broader range of ($\alpha_t$, $\beta$, $r$), and will have a better chance to break a degeneracy between them. Constraints on $\alpha_t$ are estimated from several detections and cosmological observations. Among them, the most stringent one is from the bound of the Big Bang nucleosynthesis (BBN), and requires $\alpha_t < 0.008$ rather conservatively for any reasonable ($\beta$, $r$), preferring a nearly power-law spectrum of RGWs. In light of this result, one would expect the scalar running index $\alpha_s$ to be of the same magnitude as $\alpha_t$, if both RGWs and scalar perturbations are generated by the same scalar inflation.
0903.4876
Lorenzo Sindoni
Florian Girelli, Stefano Liberati and Lorenzo Sindoni
Is the notion of time really fundamental?
9 pages, 2 figures. Fourth prize essay for the competition of the Foundational Questions Institute (fqxi.org) on the Nature of Time
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
From the Physics point of view, time is now best described through General Relativity, as part of space-time which is a dynamical object encoding gravity. Time possesses also some intrinsic irreversibility due to thermodynamics, quantum mechanical effects... This irreversibility can look puzzling since time-like loops (and hence time machines) can appear in General Relativity (for example in the Goedel universe, a solution of Einstein's equations). We take this apparent discrepancy as a warning bell pointing to us that time as we understand it, might not be fundamental and that whatever theory, lying beyond General Relativity, may not include time as we know it as a fundamental structure. We propose therefore, following the philosophy of analog models of gravity, that time and gravity might not be fundamental per se, but only emergent features. We illustrate our proposal using a toy-model where we show how the Lorentzian signature and Nordstroem gravity (a diffeomorphisms invariant scalar gravity theory) can emerge from a timeless non-dynamical space.
[ { "created": "Fri, 27 Mar 2009 19:02:20 GMT", "version": "v1" } ]
2009-03-30
[ [ "Girelli", "Florian", "" ], [ "Liberati", "Stefano", "" ], [ "Sindoni", "Lorenzo", "" ] ]
From the Physics point of view, time is now best described through General Relativity, as part of space-time which is a dynamical object encoding gravity. Time possesses also some intrinsic irreversibility due to thermodynamics, quantum mechanical effects... This irreversibility can look puzzling since time-like loops (and hence time machines) can appear in General Relativity (for example in the Goedel universe, a solution of Einstein's equations). We take this apparent discrepancy as a warning bell pointing to us that time as we understand it, might not be fundamental and that whatever theory, lying beyond General Relativity, may not include time as we know it as a fundamental structure. We propose therefore, following the philosophy of analog models of gravity, that time and gravity might not be fundamental per se, but only emergent features. We illustrate our proposal using a toy-model where we show how the Lorentzian signature and Nordstroem gravity (a diffeomorphisms invariant scalar gravity theory) can emerge from a timeless non-dynamical space.
gr-qc/9511021
Azreg-Ainou Mustapha
Mustapha Azreg-Ainou
Solutions Stationnaires en Th\'eorie de Kaluza-Klein
Minor errors corrected. 120 pages, LaTeX, no figures. A thesis submitted in conformity with the requirements for the degree of Docteur Es-Sciences at the Institut Non Lin\'eaire de Nice (INLN), France
null
null
null
gr-qc
null
Kaluza-Klein theory is a 5-dimensional Einstein general relativity; it has the interest of describing on an equal footing the laws of gravitation and electromagnetism in a geometrically unified way. We present it in Chapter 1, and we generalize it by adding to the equations of the theory the Lanczos tensor (endowed with the same physical properties as the Einstein tensor but quadratic with respect to the Riemann tensor.) One has obtained in the last decade all the spherically symmetric 2-stationary solutions (independent of time and of the extra coordinate) of the ``special" Kaluza-Klein theory. The study of the stability of these solutions against radial excitations is carried out in Chapter 2. We begin by presenting the spherically symmetric 2-static solutions; then we write and separate the perturbation-linearized equations of the 5-metric. The problem of stability against small oscillations is reduced to an eigenvalue problem which we discuss in detail in the static-solution parameter space. We show that regular solutions of non-vanishing finite energy (Kaluza-Klein solitons) --with non-euclidean spatial topology-- are stable. A broad class of singular solutions, containing among others the Schwarzschild solution, are also stable. Finally our stability results are compared to those obtained previously by Tomimatsu for a less broad class of solutions. We search in Chapter 3 for other exact stationary solutions, endowed this time with cylindrical symmetry, thus actually 4-stationary (depending on only one spacelike coordinate). First we obtain by a systematic study all the 4-stationary solutions of the special theory, some of which are interpreted as neutral or charged distributional cosmic string sources. We generalize these solutions in a following section by considering the Lanczos tensor, and we find
[ { "created": "Mon, 6 Nov 1995 15:14:10 GMT", "version": "v1" }, { "created": "Thu, 21 Dec 1995 13:41:47 GMT", "version": "v2" } ]
2008-02-03
[ [ "Azreg-Ainou", "Mustapha", "" ] ]
Kaluza-Klein theory is a 5-dimensional Einstein general relativity; it has the interest of describing on an equal footing the laws of gravitation and electromagnetism in a geometrically unified way. We present it in Chapter 1, and we generalize it by adding to the equations of the theory the Lanczos tensor (endowed with the same physical properties as the Einstein tensor but quadratic with respect to the Riemann tensor.) One has obtained in the last decade all the spherically symmetric 2-stationary solutions (independent of time and of the extra coordinate) of the ``special" Kaluza-Klein theory. The study of the stability of these solutions against radial excitations is carried out in Chapter 2. We begin by presenting the spherically symmetric 2-static solutions; then we write and separate the perturbation-linearized equations of the 5-metric. The problem of stability against small oscillations is reduced to an eigenvalue problem which we discuss in detail in the static-solution parameter space. We show that regular solutions of non-vanishing finite energy (Kaluza-Klein solitons) --with non-euclidean spatial topology-- are stable. A broad class of singular solutions, containing among others the Schwarzschild solution, are also stable. Finally our stability results are compared to those obtained previously by Tomimatsu for a less broad class of solutions. We search in Chapter 3 for other exact stationary solutions, endowed this time with cylindrical symmetry, thus actually 4-stationary (depending on only one spacelike coordinate). First we obtain by a systematic study all the 4-stationary solutions of the special theory, some of which are interpreted as neutral or charged distributional cosmic string sources. We generalize these solutions in a following section by considering the Lanczos tensor, and we find
0910.5124
Gamal G.L. Nashed
Gamal G.L. Nashed
Brane World black holes in Teleparallel Theory Equivalent to General Relativity and their Killing vectors, Energy, Momentum and Angular-Momentum
24 pages. Will appear in Chinese Phys. No. 2 (2010)
Chin.Phys.B19:020401,2010
10.1088/1674-1056/19/2/020401
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The energy-momentum tensor, which is coordinate independent, is used to calculate energy, momentum and angular-momentum of two different tetrad fields. Although, the two tetrad fields reproduce the same space-time their energies are different. Therefore, a regularized expression of the gravitational energy-momentum tensor of the teleparallel equivalent of general relativity, (TEGR), is used to make the energies of the two tetrad fields equal. The definition of the gravitational energy-momentum is used to investigate the energy within the external event horizon. The components of angular-momentum associated with these space-times are calculated. In spite that we use a static space-times, we get a non-zero component of angular-momentum! Therefore, we derive the killing vectors associated with these space-times using the definition of the Lie derivative of a second rank tensor in the framework of the TEGR to make the picture more clear.
[ { "created": "Tue, 27 Oct 2009 14:05:04 GMT", "version": "v1" } ]
2010-03-04
[ [ "Nashed", "Gamal G. L.", "" ] ]
The energy-momentum tensor, which is coordinate independent, is used to calculate energy, momentum and angular-momentum of two different tetrad fields. Although, the two tetrad fields reproduce the same space-time their energies are different. Therefore, a regularized expression of the gravitational energy-momentum tensor of the teleparallel equivalent of general relativity, (TEGR), is used to make the energies of the two tetrad fields equal. The definition of the gravitational energy-momentum is used to investigate the energy within the external event horizon. The components of angular-momentum associated with these space-times are calculated. In spite that we use a static space-times, we get a non-zero component of angular-momentum! Therefore, we derive the killing vectors associated with these space-times using the definition of the Lie derivative of a second rank tensor in the framework of the TEGR to make the picture more clear.
1408.4598
Andrea Geralico
Donato Bini, Christian Cherubini, Andrea Geralico, Robert T. Jantzen
Physical frames along circular orbits in stationary axisymmetric spacetimes
26 pages, 5 figures; published version
Gen. Relativ. Gravit. 40, 985 (2008)
10.1007/s10714-007-0587-z
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Three natural classes of orthonormal frames, namely Frenet-Serret, Fermi-Walker and parallel transported frames, exist along any timelike world line in spacetime. Their relationships are investigated for timelike circular orbits in stationary axisymmetric spacetimes, and illustrated for black hole spacetimes.
[ { "created": "Wed, 20 Aug 2014 10:40:28 GMT", "version": "v1" } ]
2015-06-22
[ [ "Bini", "Donato", "" ], [ "Cherubini", "Christian", "" ], [ "Geralico", "Andrea", "" ], [ "Jantzen", "Robert T.", "" ] ]
Three natural classes of orthonormal frames, namely Frenet-Serret, Fermi-Walker and parallel transported frames, exist along any timelike world line in spacetime. Their relationships are investigated for timelike circular orbits in stationary axisymmetric spacetimes, and illustrated for black hole spacetimes.
2111.07817
Grigory Volovik
G.E. Volovik
Gravity from symmetry breaking phase transition
6 pages, no figures, devoted to the memory of Dmitry Diakonov
null
10.1007/s10909-022-02694-z
null
gr-qc cond-mat.other hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The paper is devoted to the memory of Dmitry Diakonov. We discuss gravity emerging in the fermionic vacuum as suggested by Diakonov 10 years ago in his paper "Towards lattice-regularized Quantum Gravity". Gravity emerges in the phase transition. The order parameter in this transition is the tetrad field, which appears as the bilinear composite of the fermionic fields. This symmetry breaking gives 6 Nambu-Goldstone modes; 6 gauge bosons in the spin-connection fields, which absorb 6 NG modes and become massive gauge bosons; and 6 Higgs fields. The similar scenario of the symmetry breaking with appearance of the $5+1$ Higgs gravitons takes place in the B-phase of superfluid $^3$He. While in $^3$He-B these Higgs modes are all massive, in the GR these Higgs collective modes give rise to two massless gravitational waves.
[ { "created": "Mon, 15 Nov 2021 15:00:37 GMT", "version": "v1" }, { "created": "Tue, 16 Nov 2021 18:49:47 GMT", "version": "v2" }, { "created": "Sat, 27 Nov 2021 15:16:11 GMT", "version": "v3" }, { "created": "Wed, 15 Dec 2021 15:42:24 GMT", "version": "v4" } ]
2022-03-30
[ [ "Volovik", "G. E.", "" ] ]
The paper is devoted to the memory of Dmitry Diakonov. We discuss gravity emerging in the fermionic vacuum as suggested by Diakonov 10 years ago in his paper "Towards lattice-regularized Quantum Gravity". Gravity emerges in the phase transition. The order parameter in this transition is the tetrad field, which appears as the bilinear composite of the fermionic fields. This symmetry breaking gives 6 Nambu-Goldstone modes; 6 gauge bosons in the spin-connection fields, which absorb 6 NG modes and become massive gauge bosons; and 6 Higgs fields. The similar scenario of the symmetry breaking with appearance of the $5+1$ Higgs gravitons takes place in the B-phase of superfluid $^3$He. While in $^3$He-B these Higgs modes are all massive, in the GR these Higgs collective modes give rise to two massless gravitational waves.
2109.04477
Filip Hejda
Filip Hejda, Jos\'e P. S. Lemos, Oleg B. Zaslavskii
Extraction of energy from an extremal rotating electrovacuum black hole: Particle collisions in the equatorial plane
25 pages, 2 tables, 1 figure
Phys. Rev. D 105, 024014 (2022)
10.1103/PhysRevD.105.024014
null
gr-qc astro-ph.HE hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The collisional Penrose process received much attention when Banados, Silk and West (BSW) pointed out the possibility of test-particle collisions with arbitrarily high center-of-mass energy in the vicinity of the horizon of an extremally rotating black hole. However, the energy that can be extracted from the black hole in this promising, if simplified, scenario, called the BSW effect, turned out to be subject to unconditional upper bounds. And although such bounds were not found for the electrostatic variant of the process, this version is also astrophysically unfeasible, since it requires a maximally charged black hole. In order to deal with these deficiencies, we revisit the unified version of the BSW effect concerning collisions of charged particles in the equatorial plane of a rotating electrovacuum black hole spacetime. Performing a general analysis of energy extraction through this process, we explain in detail how the seemingly incompatible limiting cases arise. Furthermore, we demonstrate that the unconditional upper bounds on the extracted energy are absent for arbitrarily small values of the black hole electric charge. Therefore, our setup represents an intriguing simplified model for possible highly energetic processes happening around astrophysical black holes, which may spin fast but can have only a tiny electric charge induced via interaction with an external magnetic field.
[ { "created": "Thu, 9 Sep 2021 18:00:00 GMT", "version": "v1" }, { "created": "Sun, 27 Feb 2022 19:29:54 GMT", "version": "v2" } ]
2022-03-02
[ [ "Hejda", "Filip", "" ], [ "Lemos", "José P. S.", "" ], [ "Zaslavskii", "Oleg B.", "" ] ]
The collisional Penrose process received much attention when Banados, Silk and West (BSW) pointed out the possibility of test-particle collisions with arbitrarily high center-of-mass energy in the vicinity of the horizon of an extremally rotating black hole. However, the energy that can be extracted from the black hole in this promising, if simplified, scenario, called the BSW effect, turned out to be subject to unconditional upper bounds. And although such bounds were not found for the electrostatic variant of the process, this version is also astrophysically unfeasible, since it requires a maximally charged black hole. In order to deal with these deficiencies, we revisit the unified version of the BSW effect concerning collisions of charged particles in the equatorial plane of a rotating electrovacuum black hole spacetime. Performing a general analysis of energy extraction through this process, we explain in detail how the seemingly incompatible limiting cases arise. Furthermore, we demonstrate that the unconditional upper bounds on the extracted energy are absent for arbitrarily small values of the black hole electric charge. Therefore, our setup represents an intriguing simplified model for possible highly energetic processes happening around astrophysical black holes, which may spin fast but can have only a tiny electric charge induced via interaction with an external magnetic field.
1706.02376
Manuel Hohmann
Manuel Hohmann, Laur Jarv, Ulbossyn Ualikhanova
Dynamical systems approach and generic properties of $f(T)$ cosmology
45 pages, 3 figures; journal version
Phys. Rev. D 96, 043508 (2017)
10.1103/PhysRevD.96.043508
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We present a systematic analysis of the dynamics of flat Friedmann-Lema\^{i}tre-Robertson-Walker cosmological models with radiation and dust matter in generalized teleparallel $f(T)$ gravity. We show that the cosmological dynamics of this model is fully described by a function $W(H)$ of the Hubble parameter, which is constructed from the function $f(T)$. After reducing the phase space to two dimensions we derive the conditions on $W(H)$ for the occurrence of de Sitter fixed points, accelerated expansion, crossing the phantom divide, and finite time singularities. Depending on the model parameters it is possible to have a bounce (from contraction to expansion) or a turnaround (from expansion to contraction), but cyclic or oscillating scenarios are prohibited. As an illustration of the formalism we consider power law $f(T) = T + \alpha(-T)^n$ models, and show that these allow only one period of acceleration and no phantom divide crossing.
[ { "created": "Wed, 7 Jun 2017 20:42:22 GMT", "version": "v1" }, { "created": "Sun, 3 Sep 2017 15:02:59 GMT", "version": "v2" } ]
2017-09-05
[ [ "Hohmann", "Manuel", "" ], [ "Jarv", "Laur", "" ], [ "Ualikhanova", "Ulbossyn", "" ] ]
We present a systematic analysis of the dynamics of flat Friedmann-Lema\^{i}tre-Robertson-Walker cosmological models with radiation and dust matter in generalized teleparallel $f(T)$ gravity. We show that the cosmological dynamics of this model is fully described by a function $W(H)$ of the Hubble parameter, which is constructed from the function $f(T)$. After reducing the phase space to two dimensions we derive the conditions on $W(H)$ for the occurrence of de Sitter fixed points, accelerated expansion, crossing the phantom divide, and finite time singularities. Depending on the model parameters it is possible to have a bounce (from contraction to expansion) or a turnaround (from expansion to contraction), but cyclic or oscillating scenarios are prohibited. As an illustration of the formalism we consider power law $f(T) = T + \alpha(-T)^n$ models, and show that these allow only one period of acceleration and no phantom divide crossing.
gr-qc/9504029
Ding Shuxue
Shuxue Ding (Tokyo Institute of Technology)
Dynamics of Yang-Mills Cosmology Bubbles in Bartnik-McKinnon Spacetimes
Latex, 36 preprint pages, 6 unencoded figures
null
null
TIT/HEP-272/COSMO-49
gr-qc
null
We investigate the dynamics of a Yang-Mills cosmology (YMC, the FRW type spacetime) bubble in the Bartnik-McKinnon (BK) spacetimes. Because a BK spacetime can be identified to a YMC spacetime with a finite scale factor in the neighborhood of the origin, we can give a natural initial condition for the YMC bubble. The YMC bubble can smoothly emerge from the origin without an initial singularity. Under a certain condition, the bubble develops continuously and finally replaces the entire BK spacetime, the metric of which is the same as the one of the radiation dominated universe. We also discuss why an initial singularity can be avoided in the present case in spite of the singularity theorems by Hawking and Penrose.
[ { "created": "Thu, 20 Apr 1995 09:22:47 GMT", "version": "v1" }, { "created": "Mon, 1 May 1995 10:32:53 GMT", "version": "v2" } ]
2008-02-03
[ [ "Ding", "Shuxue", "", "Tokyo Institute of Technology" ] ]
We investigate the dynamics of a Yang-Mills cosmology (YMC, the FRW type spacetime) bubble in the Bartnik-McKinnon (BK) spacetimes. Because a BK spacetime can be identified to a YMC spacetime with a finite scale factor in the neighborhood of the origin, we can give a natural initial condition for the YMC bubble. The YMC bubble can smoothly emerge from the origin without an initial singularity. Under a certain condition, the bubble develops continuously and finally replaces the entire BK spacetime, the metric of which is the same as the one of the radiation dominated universe. We also discuss why an initial singularity can be avoided in the present case in spite of the singularity theorems by Hawking and Penrose.
gr-qc/0106049
Ernst Schmutzer
E.Schmutzer
Distribution of Dark Matter around a Central Body, Pioneer Effect and Fifth Force
11 pages, 7 figures, LaTeX
Astronom. Nachr. 322 (2001) 93
10.1002/1521-3994(200106)322:2<93::AID-ASNA93>3.0.CO;2-D
null
gr-qc
null
Within the framework of the Projective Unified Field Theory the distribution of a dark matter gas around a central body is calculated. As a result the well-known formulas of the Newtonian gravitational interaction are altered. This dark matter effect leads to an additional radial force (towards the center) in the equation of motion of a test body, being used for the explanation of the so-called ``Pioneer effect'', measured in the solar system, but without a convincing theoretical basis up to now. Further the relationship of the occurring new force to the so-called ``fifth force'' is discussed.
[ { "created": "Thu, 14 Jun 2001 14:16:18 GMT", "version": "v1" } ]
2009-11-07
[ [ "Schmutzer", "E.", "" ] ]
Within the framework of the Projective Unified Field Theory the distribution of a dark matter gas around a central body is calculated. As a result the well-known formulas of the Newtonian gravitational interaction are altered. This dark matter effect leads to an additional radial force (towards the center) in the equation of motion of a test body, being used for the explanation of the so-called ``Pioneer effect'', measured in the solar system, but without a convincing theoretical basis up to now. Further the relationship of the occurring new force to the so-called ``fifth force'' is discussed.
gr-qc/0302030
Gian Paolo Vacca
A. Tronconi, G.P. Vacca, G. Venturi
The Inflaton and Time in the Matter-Gravity System
14 pages, latex
Phys.Rev.D67:063517,2003
10.1103/PhysRevD.67.063517
null
gr-qc astro-ph hep-th quant-ph
null
The emergence of time in the matter-gravity system is addressed within the context of the inflationary paradigm. A quantum minisuperspace-homogeneous minimally coupled inflaton system is studied with suitable initial conditions leading to inflation and the system is approximately solved in the limit for large scale factor. Subsequently normal matter (either non homogeneous inflaton modes or lighter matter) is introduced as a perturbation and it is seen that its presence requires the coarse averaging of a gravitational wave function (which oscillates at trans-Planckian frequencies) having suitable initial conditions. Such a wave function, which is common for all types of normal matter, is associated with a ``time density'' in the sense that its modulus is related to the amount of time spent in a given interval (or the rate of flow of time). One is then finally led to an effective evolution equation (Schroedinger Schwinger-Tomonaga) for ``normal'' matter. An analogy with the emergence of a temperature in statistical mechanics is also pointed out.
[ { "created": "Mon, 10 Feb 2003 11:11:00 GMT", "version": "v1" } ]
2008-11-26
[ [ "Tronconi", "A.", "" ], [ "Vacca", "G. P.", "" ], [ "Venturi", "G.", "" ] ]
The emergence of time in the matter-gravity system is addressed within the context of the inflationary paradigm. A quantum minisuperspace-homogeneous minimally coupled inflaton system is studied with suitable initial conditions leading to inflation and the system is approximately solved in the limit for large scale factor. Subsequently normal matter (either non homogeneous inflaton modes or lighter matter) is introduced as a perturbation and it is seen that its presence requires the coarse averaging of a gravitational wave function (which oscillates at trans-Planckian frequencies) having suitable initial conditions. Such a wave function, which is common for all types of normal matter, is associated with a ``time density'' in the sense that its modulus is related to the amount of time spent in a given interval (or the rate of flow of time). One is then finally led to an effective evolution equation (Schroedinger Schwinger-Tomonaga) for ``normal'' matter. An analogy with the emergence of a temperature in statistical mechanics is also pointed out.
1712.10182
Yichen Shi
Alexandru Lupsasca, Achilleas P. Porfyriadis, Yichen Shi
Critical Emission from a High-Spin Black Hole
12 pages, 3 figures. v2: minor edits, matches published version
Phys. Rev. D 97, 064017 (2018)
10.1103/PhysRevD.97.064017
null
gr-qc astro-ph.HE hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We consider a rapidly spinning black hole surrounded by an equatorial, geometrically thin, slowly accreting disk that is stationary and axisymmetric. We analytically compute the broadening of electromagnetic line emissions from the innermost part of the disk, which resides in the near-horizon region. The result is independent of the disk's surface emissivity and therefore universal. This is an example of critical behavior in astronomy that is potentially observable by current or future telescopes.
[ { "created": "Fri, 29 Dec 2017 11:23:54 GMT", "version": "v1" }, { "created": "Thu, 22 Mar 2018 22:12:19 GMT", "version": "v2" } ]
2018-03-26
[ [ "Lupsasca", "Alexandru", "" ], [ "Porfyriadis", "Achilleas P.", "" ], [ "Shi", "Yichen", "" ] ]
We consider a rapidly spinning black hole surrounded by an equatorial, geometrically thin, slowly accreting disk that is stationary and axisymmetric. We analytically compute the broadening of electromagnetic line emissions from the innermost part of the disk, which resides in the near-horizon region. The result is independent of the disk's surface emissivity and therefore universal. This is an example of critical behavior in astronomy that is potentially observable by current or future telescopes.
2211.04929
David Kofro\v{n}
David Kofro\v{n}, Petr Kotla\v{r}\'ik
Debye superpotential for charged rings or circular currents on Kerr black hole
to appear is Phys Rev D (accepted)
null
null
null
gr-qc
http://creativecommons.org/licenses/by-nc-nd/4.0/
We provide an explicit, closed and compact expression for the Debye superpotential of a circular source. This superpotential is obtained by integrating the Green function of Teukolsky Master Equation (TME). The Debye potential itself is then, for a particular configuration, calculated in the same manner as the $\phi_0$ field component is calculated from the Green function of the TME -- by convolution of the Green function with sources. This way we provide an exact field of charged ring and circular current on the Kerr background, finalizing thus the work of Linet.
[ { "created": "Wed, 9 Nov 2022 14:58:05 GMT", "version": "v1" } ]
2022-11-10
[ [ "Kofroň", "David", "" ], [ "Kotlařík", "Petr", "" ] ]
We provide an explicit, closed and compact expression for the Debye superpotential of a circular source. This superpotential is obtained by integrating the Green function of Teukolsky Master Equation (TME). The Debye potential itself is then, for a particular configuration, calculated in the same manner as the $\phi_0$ field component is calculated from the Green function of the TME -- by convolution of the Green function with sources. This way we provide an exact field of charged ring and circular current on the Kerr background, finalizing thus the work of Linet.
gr-qc/0109074
Andri M. Gretarsson
D. R. M. Crooks, P. Sneddon, G. Cagnoli, J. Hough, S. Rowan, M. M. Fejer, E. Gustafson, R. Route, N. Nakagawa, D. Coyne, G. M. Harry, A. M. Gretarsson
Excess Mechanical Loss Associated with Dielectric Mirror Coatings on Test Masses in Interferometric Gravitational Wave Detectors
Submitted to LSC (internal) review Sept. 20, 2001. To be submitted to Phys. Lett. A
Class.Quant.Grav. 19 (2002) 883-896; Erratum-ibid. 19 (2002) 4229
10.1088/0264-9381/19/15/502
null
gr-qc
null
Interferometric gravitational wave detectors use mirrors whose substrates are formed from materials of low intrinsic mechanical dissipation. The two most likely choices for the test masses in future advanced detectors are fused silica or sapphire. These test masses must be coated to form mirrors, highly reflecting at 1064nm. We have measured the excess mechanical losses associated with adding dielectric coatings to substrates of fused silica and calculate the effect of the excess loss on the thermal noise in an advanced interferometer.
[ { "created": "Thu, 20 Sep 2001 22:00:37 GMT", "version": "v1" } ]
2009-11-07
[ [ "Crooks", "D. R. M.", "" ], [ "Sneddon", "P.", "" ], [ "Cagnoli", "G.", "" ], [ "Hough", "J.", "" ], [ "Rowan", "S.", "" ], [ "Fejer", "M. M.", "" ], [ "Gustafson", "E.", "" ], [ "Route", "R.", "" ], [ "Nakagawa", "N.", "" ], [ "Coyne", "D.", "" ], [ "Harry", "G. M.", "" ], [ "Gretarsson", "A. M.", "" ] ]
Interferometric gravitational wave detectors use mirrors whose substrates are formed from materials of low intrinsic mechanical dissipation. The two most likely choices for the test masses in future advanced detectors are fused silica or sapphire. These test masses must be coated to form mirrors, highly reflecting at 1064nm. We have measured the excess mechanical losses associated with adding dielectric coatings to substrates of fused silica and calculate the effect of the excess loss on the thermal noise in an advanced interferometer.
1902.08442
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, 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, 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. 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Narrow-band search for gravitational waves from known pulsars using the second LIGO observing run
6 figures, 4 tables
Phys. Rev. D 99, 122002 (2019)
10.1103/PhysRevD.99.122002
LIGO-P1800391
gr-qc astro-ph.IM
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Isolated spinning neutron stars, asymmetric with respect to their rotation axis, are expected to be sources of continuous gravitational waves. The most sensitive searches for these sources are based on accurate matched filtering techniques, that assume the continuous wave to be phase-locked with the pulsar beamed emission. While matched filtering maximizes the search sensitivity, a significant signal-to-noise ratio loss will happen in case of a mismatch between the assumed and the true signal phase evolution. Narrow-band algorithms allow for a small mismatch in the frequency and spin-down values of the pulsar while integrating coherently the entire data set. In this paper we describe a narrow-band search using LIGO O2 data for the continuous wave emission of 33 pulsars. No evidence for a continuous wave signal has been found and upper-limits on the gravitational wave amplitude, over the analyzed frequency and spin-down volume, have been computed for each of the targets. In this search we have surpassed the spin-down limit for some of the pulsars already present in the O1 LIGO narrow-band search, such as J1400\textminus6325 J1813\textminus1246, J1833\textminus1034, J1952+3252, and for new targets such as J0940\textminus5428 and J1747\textminus2809. For J1400\textminus6325, J1833\textminus1034 and J1747\textminus2809 this is the first time the spin-down limit is surpassed.
[ { "created": "Fri, 22 Feb 2019 11:32:46 GMT", "version": "v1" }, { "created": "Mon, 25 Feb 2019 11:38:04 GMT", "version": "v2" }, { "created": "Thu, 6 Jun 2019 15:11:35 GMT", "version": "v3" } ]
2019-07-03
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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.", "" ], [ "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.", "" ], [ "Keith", "M.", "" ], [ "Kerr", "M.", "" ], [ "Kuiper", "L.", "" ], [ "Harding", "A. K.", "" ], [ "Lyne", "A.", "" ], [ "Palfreyman", "J.", "" ], [ "Stappers", "B.", "" ], [ "Weltervrede", "P.", "" ] ]
Isolated spinning neutron stars, asymmetric with respect to their rotation axis, are expected to be sources of continuous gravitational waves. The most sensitive searches for these sources are based on accurate matched filtering techniques, that assume the continuous wave to be phase-locked with the pulsar beamed emission. While matched filtering maximizes the search sensitivity, a significant signal-to-noise ratio loss will happen in case of a mismatch between the assumed and the true signal phase evolution. Narrow-band algorithms allow for a small mismatch in the frequency and spin-down values of the pulsar while integrating coherently the entire data set. In this paper we describe a narrow-band search using LIGO O2 data for the continuous wave emission of 33 pulsars. No evidence for a continuous wave signal has been found and upper-limits on the gravitational wave amplitude, over the analyzed frequency and spin-down volume, have been computed for each of the targets. In this search we have surpassed the spin-down limit for some of the pulsars already present in the O1 LIGO narrow-band search, such as J1400\textminus6325 J1813\textminus1246, J1833\textminus1034, J1952+3252, and for new targets such as J0940\textminus5428 and J1747\textminus2809. For J1400\textminus6325, J1833\textminus1034 and J1747\textminus2809 this is the first time the spin-down limit is surpassed.
0904.4904
Kirill Bronnikov
K.A. Bronnikov, O.B. Zaslavskii
General static black holes in matter
6 pages latex
Class.Quant.Grav.26:165004,2009
10.1088/0264-9381/26/16/165004
null
gr-qc astro-ph.CO hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
For arbitrary static space-times, it is shown that an equilibrium between a Killing horizon and matter is only possible for some discrete values of the parameter $w = p_1/\rho$, where $\rho$ is the density and $p_1$ is pressure in the direction normal to the horizon. In the generic situation of a simple (non-extremal) horizon and the slowest possible density decrease near the horizon, this corresponds to $w = -1/3$, the value known for a gas of disordered cosmic strings. An admixture of "vacuum matter", characterized by $w=-1$ and nonzero density at the horizon, is also admitted. This extends the results obtained previously for static, spherically symmetric space-times. A new feature as compared to spherical symmetry is that higher-order horizons can exist in the absence of vacuum matter if the horizon is a surface of zero curvature, which can occur, e.g., in cylindrically symmetric space-times.
[ { "created": "Thu, 30 Apr 2009 18:07:39 GMT", "version": "v1" } ]
2010-04-14
[ [ "Bronnikov", "K. A.", "" ], [ "Zaslavskii", "O. B.", "" ] ]
For arbitrary static space-times, it is shown that an equilibrium between a Killing horizon and matter is only possible for some discrete values of the parameter $w = p_1/\rho$, where $\rho$ is the density and $p_1$ is pressure in the direction normal to the horizon. In the generic situation of a simple (non-extremal) horizon and the slowest possible density decrease near the horizon, this corresponds to $w = -1/3$, the value known for a gas of disordered cosmic strings. An admixture of "vacuum matter", characterized by $w=-1$ and nonzero density at the horizon, is also admitted. This extends the results obtained previously for static, spherically symmetric space-times. A new feature as compared to spherical symmetry is that higher-order horizons can exist in the absence of vacuum matter if the horizon is a surface of zero curvature, which can occur, e.g., in cylindrically symmetric space-times.
gr-qc/0507061
Sotirios Bonanos
S. Bonanos
On a choice of the Bondi radial coordinate and news function for the axisymmetric two-body problem
13 pages, LaTeX, submitted to Classical and Quantum Gravity; v2 corrected a few typos and added some comments; v3 expanded discussion and added references -- Rejected by CQG; v4: 8 pages revtex4 2 column, extensively revised, submitted to Phys Rev D; v5: 21 pages revtex4 preprint; further discussion of physical interpretation; v6: 21 pages revtex4 preprint -- final version to appear in Phys. Rev. D (2006)
Phys.Rev. D73 (2006) 124003
10.1103/PhysRevD.73.124003
null
gr-qc
null
In the Bondi formulation of the axisymmetric vacuum Einstein equations, we argue that the ``surface area'' coordinate condition determining the ``radial'' coordinate can be considered as part of the initial data and should be chosen in a way that gives information about the physical problem whose solution is sought. For the two-body problem, we choose this coordinate by imposing a condition that allows it to be interpreted, near infinity, as the (inverse of the) Newtonian potential. In this way, two quantities that specify the problem -- the separation of the two particles and their mass ratio -- enter the equations from the very beginning. The asymptotic solution (near infinity) is obtained and a natural identification of the Bondi "news function" in terms of the source parameters is suggested, leading to an expression for the radiated energy that differs from the standard quadrupole formula but agrees with recent non-linear calculations. When the free function of time describing the separation of the two particles is chosen so as to make the new expression agree with the classical result, closed-form analytic expressions are obtained, the resulting metric approaching the Schwarzschild solution with time. As all physical quantities are defined with respect to the flat metric at infinity, the physical interpretation of this solution depends strongly on how these definitions are extended to the near-zone and, in particular, how the "time" function in the near-zone is related to Bondi's null coordinate.
[ { "created": "Thu, 14 Jul 2005 09:52:30 GMT", "version": "v1" }, { "created": "Thu, 1 Sep 2005 11:35:32 GMT", "version": "v2" }, { "created": "Tue, 8 Nov 2005 09:08:24 GMT", "version": "v3" }, { "created": "Fri, 20 Jan 2006 09:18:58 GMT", "version": "v4" }, { "created": "Thu, 23 Mar 2006 09:29:58 GMT", "version": "v5" }, { "created": "Wed, 17 May 2006 10:46:40 GMT", "version": "v6" } ]
2007-05-23
[ [ "Bonanos", "S.", "" ] ]
In the Bondi formulation of the axisymmetric vacuum Einstein equations, we argue that the ``surface area'' coordinate condition determining the ``radial'' coordinate can be considered as part of the initial data and should be chosen in a way that gives information about the physical problem whose solution is sought. For the two-body problem, we choose this coordinate by imposing a condition that allows it to be interpreted, near infinity, as the (inverse of the) Newtonian potential. In this way, two quantities that specify the problem -- the separation of the two particles and their mass ratio -- enter the equations from the very beginning. The asymptotic solution (near infinity) is obtained and a natural identification of the Bondi "news function" in terms of the source parameters is suggested, leading to an expression for the radiated energy that differs from the standard quadrupole formula but agrees with recent non-linear calculations. When the free function of time describing the separation of the two particles is chosen so as to make the new expression agree with the classical result, closed-form analytic expressions are obtained, the resulting metric approaching the Schwarzschild solution with time. As all physical quantities are defined with respect to the flat metric at infinity, the physical interpretation of this solution depends strongly on how these definitions are extended to the near-zone and, in particular, how the "time" function in the near-zone is related to Bondi's null coordinate.
1309.2012
David Hilditch
David Hilditch
An Introduction to Well-posedness and Free-evolution
Lecture notes from the NRHEP spring school held at IST-Lisbon, March 2013. To be published by IJMPA (V. Cardoso, L. Gualtieri, C. Herdeiro and U. Sperhake, Eds., 2013)
International Journal of Modern Physics A Vol. 28 (2013) 1340015
10.1142/S0217751X13400150
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
These lecture notes accompany two classes given at the NRHEP2 school. In the first lecture I introduce the basic concepts used for analyzing well-posedness, that is the existence of a unique solution depending continuously on given data, of evolution partial differential equations. I show how strong hyperbolicity guarantees well-posedness of the initial value problem. Symmetric hyperbolic systems are shown to render the initial boundary value problem well-posed with maximally dissipative boundary conditions. I discuss the Laplace-Fourier method for analyzing the initial boundary value problem. Finally I state how these notions extend to systems that are first order in time and second order in space. In the second lecture I discuss the effect that the gauge freedom of electromagnetism has on the PDE status of the initial value problem. I focus on gauge choices, strong-hyperbolicity and the construction of constraint preserving boundary conditions. I show that strongly hyperbolic pure gauges can be used to build strongly hyperbolic formulations. I examine which of these formulations is additionally symmetric hyperbolic and finally demonstrate that the system can be made boundary stable.
[ { "created": "Sun, 8 Sep 2013 21:27:46 GMT", "version": "v1" } ]
2013-09-10
[ [ "Hilditch", "David", "" ] ]
These lecture notes accompany two classes given at the NRHEP2 school. In the first lecture I introduce the basic concepts used for analyzing well-posedness, that is the existence of a unique solution depending continuously on given data, of evolution partial differential equations. I show how strong hyperbolicity guarantees well-posedness of the initial value problem. Symmetric hyperbolic systems are shown to render the initial boundary value problem well-posed with maximally dissipative boundary conditions. I discuss the Laplace-Fourier method for analyzing the initial boundary value problem. Finally I state how these notions extend to systems that are first order in time and second order in space. In the second lecture I discuss the effect that the gauge freedom of electromagnetism has on the PDE status of the initial value problem. I focus on gauge choices, strong-hyperbolicity and the construction of constraint preserving boundary conditions. I show that strongly hyperbolic pure gauges can be used to build strongly hyperbolic formulations. I examine which of these formulations is additionally symmetric hyperbolic and finally demonstrate that the system can be made boundary stable.
gr-qc/9404040
Robert Mann
K.C.K. Chan and R.B. Mann
Static Charged Black Holes in $(2+1)$ Dimensional Dilaton Gravity
17 pgs., 4 figures (appended as postscript files), WATPHYS-TH94/01 (one reference added)
Phys.Rev.D50:6385,1994; Erratum-ibid.D52:2600,1995; Phys.Rev.D52:2600,1995
10.1103/PhysRevD.50.6385 10.1103/PhysRevD.52.2600
null
gr-qc
null
A one parameter family of static charged black hole solutions in $(2+1)$-dimensional general relativity minimally coupled to a dilaton $\phi\propto ln({r\over\beta})$ with a potential term $e^{b\phi}\Lambda$ is obtained. Their causal strutures are investigated, and thermodynamical temperature and entropy are computed. One particular black hole in the family has the same thermodynamical properties as the Schwarzschild black hole in $3+1$ dimensions. Solutions with cosmological horizons are also discussed. Finally, a class of black holes arising from the dilaton with a negative kinetic term (tachyon) is briefly discussed.
[ { "created": "Thu, 21 Apr 1994 21:12:08 GMT", "version": "v1" }, { "created": "Mon, 25 Apr 1994 16:08:09 GMT", "version": "v2" } ]
2014-11-17
[ [ "Chan", "K. C. K.", "" ], [ "Mann", "R. B.", "" ] ]
A one parameter family of static charged black hole solutions in $(2+1)$-dimensional general relativity minimally coupled to a dilaton $\phi\propto ln({r\over\beta})$ with a potential term $e^{b\phi}\Lambda$ is obtained. Their causal strutures are investigated, and thermodynamical temperature and entropy are computed. One particular black hole in the family has the same thermodynamical properties as the Schwarzschild black hole in $3+1$ dimensions. Solutions with cosmological horizons are also discussed. Finally, a class of black holes arising from the dilaton with a negative kinetic term (tachyon) is briefly discussed.
1301.2424
Luis Herrera
L. Herrera, A. Di Prisco, J. Iba\~nez and J. Ospino
Axially symmetric static sources: A general framework and some analytical solutions
Revtex4, 12 pages. Published in Phys. Rev. D
Phys. Rev. D 87, 024014 (2013)
10.1103/PhysRevD.87.024014
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We provide all basic equations and concepts required to carry out a general study on axially symmetric static sources. The Einstein equations and the conservation equations are written down for a general anisotropic static fluid endowed with axial symmetry. The structure scalars are calculated and the inhomogeneity factors are identified. Finally some exact analytical solutions were found. One of these solutions describes an incompressible spheroid with isotropic pressure and becomes the well known interior Schwarzschild solution in the spherically symmetric limit, however it cannot be matched smoothly to any Weyl exterior metric. Another family of solutions was found that corresponds to an anisotropic fluid distribution and can in principle be matched to a Weyl exterior.
[ { "created": "Fri, 11 Jan 2013 09:11:03 GMT", "version": "v1" } ]
2015-06-12
[ [ "Herrera", "L.", "" ], [ "Di Prisco", "A.", "" ], [ "Ibañez", "J.", "" ], [ "Ospino", "J.", "" ] ]
We provide all basic equations and concepts required to carry out a general study on axially symmetric static sources. The Einstein equations and the conservation equations are written down for a general anisotropic static fluid endowed with axial symmetry. The structure scalars are calculated and the inhomogeneity factors are identified. Finally some exact analytical solutions were found. One of these solutions describes an incompressible spheroid with isotropic pressure and becomes the well known interior Schwarzschild solution in the spherically symmetric limit, however it cannot be matched smoothly to any Weyl exterior metric. Another family of solutions was found that corresponds to an anisotropic fluid distribution and can in principle be matched to a Weyl exterior.
2009.14058
Mariusz P. Dabrowski
Adam Balcerzak, Samuel Barroso-Bellido, Mariusz P. Dabrowski, and Salvador Robles-Perez
Entanglement entropy at critical points of classical evolution in oscillatory and exotic singularity multiverse models
14 pages, 11 figures, 1 table, REVTEX4-1
Phys. Rev. D 103, 043507 (2021)
10.1103/PhysRevD.103.043507
null
gr-qc hep-th
http://creativecommons.org/licenses/by/4.0/
Using the 3rd quantization formalism we study the quantum entanglement of universes created in pairs within the framework of standard homogeneous and isotropic cosmology. In particular, we investigate entanglement quantities (entropy, temperature) around maxima, minima and inflection points of the classical evolution. The novelty from previous works is that we show how the entanglement changes in an extended minisuperspace parameterised by the scale factor and additionally, by the massless scalar field. We study the entanglement quantities for the universes which classically exhibit Big-Bang and other than Big-Bang (exotic) singularities such as Big-Brake, Big-Freeze, Big-Separation, and Little-Rip. While taking into account the scalar field, we find that the entanglement entropy is finite at the Big-Bang singularity and diverges at maxima or minima of expansion. As for the exotic singularity models we find that the entanglement entropy or the temperature in all the critical points and singularities is either finite or infinite, but it never vanishes. This shows that each of the universes of a pair is entangled to a degree parametrized by the entanglement quantities which measure the quantumness of the system. Apart from the von Neumann entanglement entropy, we also check the behaviour of the the Tsallis and the Renyi entanglement entropies, and find that they behave similarly as the meters of the quantumness. Finally, we find that the best-fit relation between the entanglement entropy and the Hubble parameter (which classically marks special points of the universe evolution) is of the logarithmic shape, and not polynomial, as one could initially expect.
[ { "created": "Tue, 29 Sep 2020 14:46:58 GMT", "version": "v1" } ]
2021-02-10
[ [ "Balcerzak", "Adam", "" ], [ "Barroso-Bellido", "Samuel", "" ], [ "Dabrowski", "Mariusz P.", "" ], [ "Robles-Perez", "Salvador", "" ] ]
Using the 3rd quantization formalism we study the quantum entanglement of universes created in pairs within the framework of standard homogeneous and isotropic cosmology. In particular, we investigate entanglement quantities (entropy, temperature) around maxima, minima and inflection points of the classical evolution. The novelty from previous works is that we show how the entanglement changes in an extended minisuperspace parameterised by the scale factor and additionally, by the massless scalar field. We study the entanglement quantities for the universes which classically exhibit Big-Bang and other than Big-Bang (exotic) singularities such as Big-Brake, Big-Freeze, Big-Separation, and Little-Rip. While taking into account the scalar field, we find that the entanglement entropy is finite at the Big-Bang singularity and diverges at maxima or minima of expansion. As for the exotic singularity models we find that the entanglement entropy or the temperature in all the critical points and singularities is either finite or infinite, but it never vanishes. This shows that each of the universes of a pair is entangled to a degree parametrized by the entanglement quantities which measure the quantumness of the system. Apart from the von Neumann entanglement entropy, we also check the behaviour of the the Tsallis and the Renyi entanglement entropies, and find that they behave similarly as the meters of the quantumness. Finally, we find that the best-fit relation between the entanglement entropy and the Hubble parameter (which classically marks special points of the universe evolution) is of the logarithmic shape, and not polynomial, as one could initially expect.
1901.10069
Amit Ghosh
Amit Ghosh
Hawking Radiation -- Revisited
12 pages
null
null
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper we revisited Hawking radiation in the light of the original calculations of Hawking and Wald and found that some additional insights can be gained. We review a "derivation" of the field theory Hilbert space from the space of solutions, followed by the calculation of Bogoliubov coefficients in a collapsed spacetime from first principles. We show that these calculations can be generalized to the case of local Killing horizons and also to asymptotically non-flat spaces.
[ { "created": "Tue, 29 Jan 2019 02:18:24 GMT", "version": "v1" } ]
2019-01-30
[ [ "Ghosh", "Amit", "" ] ]
In this paper we revisited Hawking radiation in the light of the original calculations of Hawking and Wald and found that some additional insights can be gained. We review a "derivation" of the field theory Hilbert space from the space of solutions, followed by the calculation of Bogoliubov coefficients in a collapsed spacetime from first principles. We show that these calculations can be generalized to the case of local Killing horizons and also to asymptotically non-flat spaces.
2101.05987
Jian-Pin Wu
Jiali Shi and Jian-Pin Wu
Dynamics of k-essence in loop quantum cosmology
23 pages, 13 figures
null
10.1088/1674-1137/abe111
null
gr-qc astro-ph.CO hep-th
http://creativecommons.org/licenses/by/4.0/
In this paper, we study the dynamics of k-essence in loop quantum cosmology (LQC). The study indicates that the loop quantum gravity (LQG) effect plays a key role only in the early epoch of the universe and is diluted at the later stage. The fixed points in LQC are basically consistent with that in standard Friedmann-Robertson-Walker (FRW) cosmology. For most of the attractor solutions, the stability conditions in LQC are in agreement with that for the standard FRW universe. But for some special fixed point, more tighter constraints are imposed thanks to the LQG effect.
[ { "created": "Fri, 15 Jan 2021 06:49:37 GMT", "version": "v1" } ]
2021-05-26
[ [ "Shi", "Jiali", "" ], [ "Wu", "Jian-Pin", "" ] ]
In this paper, we study the dynamics of k-essence in loop quantum cosmology (LQC). The study indicates that the loop quantum gravity (LQG) effect plays a key role only in the early epoch of the universe and is diluted at the later stage. The fixed points in LQC are basically consistent with that in standard Friedmann-Robertson-Walker (FRW) cosmology. For most of the attractor solutions, the stability conditions in LQC are in agreement with that for the standard FRW universe. But for some special fixed point, more tighter constraints are imposed thanks to the LQG effect.
0905.3168
Alejandro Perez
Jonathan Engle, Karim Noui, and Alejandro Perez
Black hole entropy and SU(2) Chern-Simons theory
Final form, to appear in Phys. Rev. Lett. Some extra details on the constraint algebra added, some details on the quantization have been omitted to comply with PRL length standards (they appear however in arXiv:1006.0634)
Phys.Rev.Lett.105:031302,2010
10.1103/PhysRevLett.105.031302
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Black holes in equilibrium can be defined locally in terms of the so-called isolated horizon boundary condition given on a null surface representing the event horizon. We show that this boundary condition can be treated in a manifestly SU(2) invariant manner. Upon quantization, state counting is expressed in terms of the dimension of Chern-Simons Hilbert spaces on a sphere with marked points. Moreover, the counting can be mapped to counting the number of SU(2) intertwiners compatible with the spins that label the defects. The resulting BH entropy is proportional to a_H with logarithmic corrections \Delta S=-3/2 \log a_H. Our treatment from first principles completely settles previous controversies concerning the counting of states.
[ { "created": "Tue, 19 May 2009 20:58:47 GMT", "version": "v1" }, { "created": "Thu, 9 Jul 2009 10:22:36 GMT", "version": "v2" }, { "created": "Wed, 30 Jun 2010 13:47:31 GMT", "version": "v3" } ]
2014-11-20
[ [ "Engle", "Jonathan", "" ], [ "Noui", "Karim", "" ], [ "Perez", "Alejandro", "" ] ]
Black holes in equilibrium can be defined locally in terms of the so-called isolated horizon boundary condition given on a null surface representing the event horizon. We show that this boundary condition can be treated in a manifestly SU(2) invariant manner. Upon quantization, state counting is expressed in terms of the dimension of Chern-Simons Hilbert spaces on a sphere with marked points. Moreover, the counting can be mapped to counting the number of SU(2) intertwiners compatible with the spins that label the defects. The resulting BH entropy is proportional to a_H with logarithmic corrections \Delta S=-3/2 \log a_H. Our treatment from first principles completely settles previous controversies concerning the counting of states.
1012.1307
Parampreet Singh
Parampreet Singh, Francesca Vidotto
Exotic singularities and spatially curved Loop Quantum Cosmology
12 pages, 9 figures
Phys.Rev.D83:064027,2011
10.1103/PhysRevD.83.064027
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We investigate the occurrence of various exotic spacelike singularities in the past and the future evolution of $k = \pm 1$ Friedmann-Robertson-Walker model and loop quantum cosmology using a sufficiently general phenomenological model for the equation of state. We highlight the non-trivial role played by the intrinsic curvature for these singularities and the new physics which emerges at the Planck scale. We show that quantum gravity effects generically resolve all strong curvature singularities including big rip and big freeze singularities. The weak singularities, which include sudden and big brake singularities are ignored by quantum gravity when spatial curvature is negative, as was previously found for the spatially flat model. Interestingly, for the spatially closed model there exist cases where weak singularities may be resolved when they occur in the past evolution. The spatially closed model exhibits another novel feature. For a particular class of equation of state, this model also exhibits an additional physical branch in loop quantum cosmology, a baby universe separated from the parent branch. Our analysis generalizes previous results obtained on the resolution of strong curvature singularities in flat models to isotropic spacetimes with non-zero spatial curvature.
[ { "created": "Mon, 6 Dec 2010 20:44:16 GMT", "version": "v1" } ]
2015-03-17
[ [ "Singh", "Parampreet", "" ], [ "Vidotto", "Francesca", "" ] ]
We investigate the occurrence of various exotic spacelike singularities in the past and the future evolution of $k = \pm 1$ Friedmann-Robertson-Walker model and loop quantum cosmology using a sufficiently general phenomenological model for the equation of state. We highlight the non-trivial role played by the intrinsic curvature for these singularities and the new physics which emerges at the Planck scale. We show that quantum gravity effects generically resolve all strong curvature singularities including big rip and big freeze singularities. The weak singularities, which include sudden and big brake singularities are ignored by quantum gravity when spatial curvature is negative, as was previously found for the spatially flat model. Interestingly, for the spatially closed model there exist cases where weak singularities may be resolved when they occur in the past evolution. The spatially closed model exhibits another novel feature. For a particular class of equation of state, this model also exhibits an additional physical branch in loop quantum cosmology, a baby universe separated from the parent branch. Our analysis generalizes previous results obtained on the resolution of strong curvature singularities in flat models to isotropic spacetimes with non-zero spatial curvature.
1705.02416
Peng Huang
Peng Huang, Yue Huang
Dark energy and normalization of cosmological wave function in modified gravitations
10 pages, no figure
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Based on Wheeler-DeWitt equation derived from general relativity, it had been found that only dark energy can lead to a normalizable cosmological wave function. It is shown in the present work that, for dRGT gravity, Eddington-inspired-Born-Infeld gravity and Ho$\check{\text{r}}$ava-Lifshitz gravity, the previous conclusion can also stand well in quantum cosmology induced from these modified gravities. This observation implies that there might be a universal relation between dark energy and normalizability of the cosmological wave function.
[ { "created": "Fri, 5 May 2017 23:18:48 GMT", "version": "v1" } ]
2017-05-09
[ [ "Huang", "Peng", "" ], [ "Huang", "Yue", "" ] ]
Based on Wheeler-DeWitt equation derived from general relativity, it had been found that only dark energy can lead to a normalizable cosmological wave function. It is shown in the present work that, for dRGT gravity, Eddington-inspired-Born-Infeld gravity and Ho$\check{\text{r}}$ava-Lifshitz gravity, the previous conclusion can also stand well in quantum cosmology induced from these modified gravities. This observation implies that there might be a universal relation between dark energy and normalizability of the cosmological wave function.
1905.08012
Cosimo Bambi
Askar B. Abdikamalov, Dimitry Ayzenberg, Cosimo Bambi, Sourabh Nampalliwar, Ashutosh Tripathi, Jelen Wong, Yerong Xu, Jinli Yan, Yunfeng Yan, Yuchan Yang
Testing general relativity with supermassive black holes using X-ray reflection spectroscopy
22 pages, 12 figures. Review article prepared for a Special Issue of Universe and based on some talks given at the meeting "Recent Progress in Relativistic Astrophysics" (6-8 May 2019, Shanghai, China)
Proceedings 17, 2 (2019)
10.3390/proceedings2019017002
null
gr-qc astro-ph.HE
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper, we review our current efforts to test General Relativity in the strong field regime by studying the reflection spectrum of supermassive black holes. So far we have analyzed 11 sources with observations of NuSTAR, Suzaku, Swift, and XMM-Newton. Our results are consistent with general relativity, according to which the spacetime metric around astrophysical black holes should be well approximated by the Kerr solution. We discuss the systematic uncertainties in our model and we present a preliminary study on the impact of some of them on the measurement of the spacetime metric.
[ { "created": "Mon, 20 May 2019 11:57:48 GMT", "version": "v1" } ]
2019-06-19
[ [ "Abdikamalov", "Askar B.", "" ], [ "Ayzenberg", "Dimitry", "" ], [ "Bambi", "Cosimo", "" ], [ "Nampalliwar", "Sourabh", "" ], [ "Tripathi", "Ashutosh", "" ], [ "Wong", "Jelen", "" ], [ "Xu", "Yerong", "" ], [ "Yan", "Jinli", "" ], [ "Yan", "Yunfeng", "" ], [ "Yang", "Yuchan", "" ] ]
In this paper, we review our current efforts to test General Relativity in the strong field regime by studying the reflection spectrum of supermassive black holes. So far we have analyzed 11 sources with observations of NuSTAR, Suzaku, Swift, and XMM-Newton. Our results are consistent with general relativity, according to which the spacetime metric around astrophysical black holes should be well approximated by the Kerr solution. We discuss the systematic uncertainties in our model and we present a preliminary study on the impact of some of them on the measurement of the spacetime metric.
0801.3781
Tae Hoon Lee
S. T. Hong, J. Lee, T. H. Lee, and P. OH
Higher dimensional cosmological model with a phantom field
4 pages, 2 figures; References added
Phys.Rev.D78:047503,2008
10.1103/PhysRevD.78.047503
null
gr-qc
null
We consider a higher dimensional gravity theory with a negative kinetic energy scalar field and a cosmological constant. We find that the theory admits an exact cosmological solution for the scale factor of our universe. It has the feature that the universe undergoes a continuous transition from deceleration to acceleration at some finite time. This transition time can be interpreted as that of recent acceleration of our universe.
[ { "created": "Thu, 24 Jan 2008 15:21:25 GMT", "version": "v1" }, { "created": "Mon, 4 Feb 2008 04:53:48 GMT", "version": "v2" }, { "created": "Wed, 21 May 2008 05:29:41 GMT", "version": "v3" } ]
2008-11-26
[ [ "Hong", "S. T.", "" ], [ "Lee", "J.", "" ], [ "Lee", "T. H.", "" ], [ "OH", "P.", "" ] ]
We consider a higher dimensional gravity theory with a negative kinetic energy scalar field and a cosmological constant. We find that the theory admits an exact cosmological solution for the scale factor of our universe. It has the feature that the universe undergoes a continuous transition from deceleration to acceleration at some finite time. This transition time can be interpreted as that of recent acceleration of our universe.
1503.04434
Sunil Maurya DR.
S.K.Maurya, Y.K. Gupta, M.K. Jasim
Relativistic modelling of stable anisotropic super-dense star
Accepted in Reports on Mathematical Physics, ISSN: 0034-4877- (ELSEVIER), 23 pages, 5 figures. arXiv admin note: text overlap with arXiv:1502.03378, arXiv:1410.5808 by other authors
null
10.1016/S0034-4877(15)30016-1
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In the present article we have obtained new set of exact solutions of Einstein field equations for anisotropic fluid spheres by using the Herrera et al.[1] algorithm. The anisotropic fluid solution so obtained join continuously to Schwarzschild exterior solution across the pressure free boundary. It is observed that most of the new anisotropic solutions are well behaved and utilized to construct the super-dense star models such as neutron star and pulsars.
[ { "created": "Sun, 15 Mar 2015 15:25:38 GMT", "version": "v1" }, { "created": "Mon, 13 Apr 2015 16:47:26 GMT", "version": "v2" } ]
2015-09-30
[ [ "Maurya", "S. K.", "" ], [ "Gupta", "Y. K.", "" ], [ "Jasim", "M. K.", "" ] ]
In the present article we have obtained new set of exact solutions of Einstein field equations for anisotropic fluid spheres by using the Herrera et al.[1] algorithm. The anisotropic fluid solution so obtained join continuously to Schwarzschild exterior solution across the pressure free boundary. It is observed that most of the new anisotropic solutions are well behaved and utilized to construct the super-dense star models such as neutron star and pulsars.
gr-qc/9703066
Bernd Bruegmann
Steven Brandt, Bernd Bruegmann
A simple construction of initial data for multiple black holes
4 pages, LaTeX (RevTeX), minor changes, improved presentation, to appear in PRL
Phys.Rev.Lett.78:3606-3609,1997
10.1103/PhysRevLett.78.3606
null
gr-qc
null
We consider the initial data problem for several black holes in vacuum with arbitrary momenta and spins on a three space with punctures. We compactify the internal asymptotically flat regions to obtain a computational domain without inner boundaries. When treated numerically, this leads to a significant simplification over the conventional approach which is based on throats and isometry conditions. In this new setting it is possible to obtain existence and uniqueness of solutions to the Hamiltonian constraint.
[ { "created": "Mon, 24 Mar 1997 11:38:22 GMT", "version": "v1" }, { "created": "Mon, 21 Apr 1997 12:19:48 GMT", "version": "v2" } ]
2008-11-26
[ [ "Brandt", "Steven", "" ], [ "Bruegmann", "Bernd", "" ] ]
We consider the initial data problem for several black holes in vacuum with arbitrary momenta and spins on a three space with punctures. We compactify the internal asymptotically flat regions to obtain a computational domain without inner boundaries. When treated numerically, this leads to a significant simplification over the conventional approach which is based on throats and isometry conditions. In this new setting it is possible to obtain existence and uniqueness of solutions to the Hamiltonian constraint.
0805.4696
Jonathan Engle
Jonathan Engle and Roberto Pereira
Regularization and finiteness of the Lorentzian LQG vertices
16 pages; Added an appendix presenting the gauge-fixing interpretation, added three references, and made some minor changes
Phys.Rev.D79:084034,2009
10.1103/PhysRevD.79.084034
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We give an explicit form for the Lorentzian vertices recently introduced for possibly defining the dynamics of loop quantum gravity. As a result of so doing, a natural regularization of the vertices is suggested. The regularized vertices are then proven to be finite. An interpretation of the regularization in terms of a gauge-fixing is also given.
[ { "created": "Fri, 30 May 2008 08:40:39 GMT", "version": "v1" }, { "created": "Thu, 2 Apr 2009 21:57:16 GMT", "version": "v2" } ]
2009-11-06
[ [ "Engle", "Jonathan", "" ], [ "Pereira", "Roberto", "" ] ]
We give an explicit form for the Lorentzian vertices recently introduced for possibly defining the dynamics of loop quantum gravity. As a result of so doing, a natural regularization of the vertices is suggested. The regularized vertices are then proven to be finite. An interpretation of the regularization in terms of a gauge-fixing is also given.
2107.02889
Pardyumn Kumar Sahoo
Avik De, Tee-How Loo, Raja Solanki and P.K. Sahoo
How a conformally flat (GR)4 impacts Gauss-Bonnet gravity?
10 pages, 6 figures: Revised version submitted to Fortschritte der Physik - Progress of Physics
Fortschritte der Physik (2021) 69(10), 2100088
10.1002/prop.202100088
null
gr-qc
http://creativecommons.org/licenses/by/4.0/
First and foremost, we show that a 4-dimensional conformally flat generalized Ricci recurrent spacetime $(GR)_4$ is an Einstein manifold. We examine such a spacetime as a solution of $f(R, G)$-gravity theory and it is shown that the additional terms from the modification of the gravitational sector can be expressed as a perfect fluid. Several energy conditions are investigated with $f(R, G) = R +\sqrt{G}$ and $f(R, G) = R^2+GlnG$. For both the models, weak, null and dominant energy conditions are satisfied while strong energy condition is violated, which is a good agreement with the recent observational studies which reveals that the current universe is in accelerating phase.
[ { "created": "Mon, 5 Jul 2021 15:28:12 GMT", "version": "v1" }, { "created": "Sat, 24 Jul 2021 10:18:33 GMT", "version": "v2" } ]
2021-11-16
[ [ "De", "Avik", "" ], [ "Loo", "Tee-How", "" ], [ "Solanki", "Raja", "" ], [ "Sahoo", "P. K.", "" ] ]
First and foremost, we show that a 4-dimensional conformally flat generalized Ricci recurrent spacetime $(GR)_4$ is an Einstein manifold. We examine such a spacetime as a solution of $f(R, G)$-gravity theory and it is shown that the additional terms from the modification of the gravitational sector can be expressed as a perfect fluid. Several energy conditions are investigated with $f(R, G) = R +\sqrt{G}$ and $f(R, G) = R^2+GlnG$. For both the models, weak, null and dominant energy conditions are satisfied while strong energy condition is violated, which is a good agreement with the recent observational studies which reveals that the current universe is in accelerating phase.
2111.14639
Raihaneh Moti
Raihaneh Moti (Ferdowsi U.), Ali Shojai (Tehran U.)
On the quantum gravastar
null
null
10.1142/S0218271822500675
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper, we show that it is possible to have pure quantum gravastar solution to the quantum improved Einstein equations. Such an object is essentially a gravastar in which the thin layer of matter is replaced by quantum effects. The metric of a pure quantum gravastar is obtained and its stability is discussed.
[ { "created": "Mon, 29 Nov 2021 15:53:16 GMT", "version": "v1" }, { "created": "Mon, 29 Aug 2022 07:18:53 GMT", "version": "v2" } ]
2022-08-30
[ [ "Moti", "Raihaneh", "", "Ferdowsi U." ], [ "Shojai", "Ali", "", "Tehran U." ] ]
In this paper, we show that it is possible to have pure quantum gravastar solution to the quantum improved Einstein equations. Such an object is essentially a gravastar in which the thin layer of matter is replaced by quantum effects. The metric of a pure quantum gravastar is obtained and its stability is discussed.
0808.2271
L. C. Garcia de Andrade
Garcia de Andrade
Kerr-Schild Riemannian acoustic black holes in dynamo plasma laboratory
Departamento de fisica teorica-if-uerj-Brasil
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Since Alfven, dynamo and sound waves and the existence of general relativistic black holes are well stablished in plasma physics, this provides enough motivation to investigate the presence of acoustic black-hole effective metric of analogue Einstein's gravity in dynamo flows. From nonlinear dynamo equations, one obtains a non-homogeneous wave equation where it is shown that the non-homogeneous factor is proportional to time evolution of the compressibility factor. In the Navier-Stokes case for a finite Reynolds number the acoustic black-holes also exists on the stretching plasma flows. In the magnetostatic case the dynamo is marginal. Analog models are usually applied to a superfluid analog spacetime, instead of the plasma setting used here. A coupled nonlinear plasma flow solution is found for the dynamo equation where the effective black hole solution of the scalar effective equation yields an imaginary part of the growth of magnetic field. Therefore though the real part of the growth rate of the magnetic field is negative or null, since there is a temporal oscillation in magnetic field, the solution represents a slow dynamo. Thus acoustic black holes are shown to definitely contribute to dynamo action of the effective plasma spacetime. It is suggested that a fast dynamo effective spacetime may also contain an acoustic black hole. I the case of planar waves the effective metric can be cast in Kerr-Schild spacetime form. The Killing symmetries are explicitly given in this metric and the growth of dynamo waves.
[ { "created": "Sat, 16 Aug 2008 20:43:49 GMT", "version": "v1" } ]
2008-08-19
[ [ "de Andrade", "Garcia", "" ] ]
Since Alfven, dynamo and sound waves and the existence of general relativistic black holes are well stablished in plasma physics, this provides enough motivation to investigate the presence of acoustic black-hole effective metric of analogue Einstein's gravity in dynamo flows. From nonlinear dynamo equations, one obtains a non-homogeneous wave equation where it is shown that the non-homogeneous factor is proportional to time evolution of the compressibility factor. In the Navier-Stokes case for a finite Reynolds number the acoustic black-holes also exists on the stretching plasma flows. In the magnetostatic case the dynamo is marginal. Analog models are usually applied to a superfluid analog spacetime, instead of the plasma setting used here. A coupled nonlinear plasma flow solution is found for the dynamo equation where the effective black hole solution of the scalar effective equation yields an imaginary part of the growth of magnetic field. Therefore though the real part of the growth rate of the magnetic field is negative or null, since there is a temporal oscillation in magnetic field, the solution represents a slow dynamo. Thus acoustic black holes are shown to definitely contribute to dynamo action of the effective plasma spacetime. It is suggested that a fast dynamo effective spacetime may also contain an acoustic black hole. I the case of planar waves the effective metric can be cast in Kerr-Schild spacetime form. The Killing symmetries are explicitly given in this metric and the growth of dynamo waves.
gr-qc/0207002
Choquet-Bruhat
Yvonne Choquet-Bruhat and James W. York
Bianchi - Euler system for relativistice fluids and Bel - Robinson type energy
10 pages
null
null
null
gr-qc
null
We write a first order symmetric hyperbolic system coupling the Riemann with the dynamical acceleration of a relativistic fluid. W determine the associated, coupled, Bel - Robinson energy, and the integral equality that it satisfies.
[ { "created": "Sat, 29 Jun 2002 13:46:32 GMT", "version": "v1" } ]
2007-05-23
[ [ "Choquet-Bruhat", "Yvonne", "" ], [ "York", "James W.", "" ] ]
We write a first order symmetric hyperbolic system coupling the Riemann with the dynamical acceleration of a relativistic fluid. W determine the associated, coupled, Bel - Robinson energy, and the integral equality that it satisfies.
2310.16025
Sophia Morton
Sophia Morton, Stefano Rinaldi, Alejandro Torres-Orjuela, Andrea Derdzinski, Maria Paola Vaccaro, Walter Del Pozzo
GW190521: a binary black hole merger inside an active galactic nucleus?
11 pages, 5 figures
null
null
null
gr-qc astro-ph.CO astro-ph.HE
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
GW190521, the most massive binary black hole merger confidently detected by the LIGO-Virgo-KAGRA collaboration, is the first gravitational-wave observation of an intermediate-mass black hole. The signal was followed approximately 34 days later by flare ZTF19abanrhr, detected in AGN J124942.3+344929 by the Zwicky Transient Facility at the 78% spatial contour for GW190521s sky localization. Using the GWTC-2.1 data release, we find that the association between GW190521 and flare ZTF19abanrhr as its electromagnetic counterpart is preferred over a random coincidence of the two transients with a log Bayes factor of 8.6, corresponding to an odds ratio of $\sim$ 5400 to 1 for equal prior odds and $\sim$ 400 to 1 assuming an astrophysical prior odds of 1/13. Given the association, the multi-messenger signal allows for an estimation of the Hubble constant, finding $H_0 = 102^{+27}_{-25}\mathrm{\ km \ s^{-1} \ Mpc^{-1}}$ when solely analyzing GW190521 and $79.2^{+17.6}_{-9.6}\mathrm{\ km \ s^{-1} \ Mpc^{-1}}$ assuming prior information from the binary neutron star merger GW170817, both consistent with the existing literature.
[ { "created": "Tue, 24 Oct 2023 17:41:58 GMT", "version": "v1" }, { "created": "Thu, 14 Dec 2023 20:13:44 GMT", "version": "v2" } ]
2023-12-18
[ [ "Morton", "Sophia", "" ], [ "Rinaldi", "Stefano", "" ], [ "Torres-Orjuela", "Alejandro", "" ], [ "Derdzinski", "Andrea", "" ], [ "Vaccaro", "Maria Paola", "" ], [ "Del Pozzo", "Walter", "" ] ]
GW190521, the most massive binary black hole merger confidently detected by the LIGO-Virgo-KAGRA collaboration, is the first gravitational-wave observation of an intermediate-mass black hole. The signal was followed approximately 34 days later by flare ZTF19abanrhr, detected in AGN J124942.3+344929 by the Zwicky Transient Facility at the 78% spatial contour for GW190521s sky localization. Using the GWTC-2.1 data release, we find that the association between GW190521 and flare ZTF19abanrhr as its electromagnetic counterpart is preferred over a random coincidence of the two transients with a log Bayes factor of 8.6, corresponding to an odds ratio of $\sim$ 5400 to 1 for equal prior odds and $\sim$ 400 to 1 assuming an astrophysical prior odds of 1/13. Given the association, the multi-messenger signal allows for an estimation of the Hubble constant, finding $H_0 = 102^{+27}_{-25}\mathrm{\ km \ s^{-1} \ Mpc^{-1}}$ when solely analyzing GW190521 and $79.2^{+17.6}_{-9.6}\mathrm{\ km \ s^{-1} \ Mpc^{-1}}$ assuming prior information from the binary neutron star merger GW170817, both consistent with the existing literature.
1904.02367
Owen Pavel Fern\'andez Piedra
Owen Pavel Fern\'andez Piedra
Vacuum polarization of the quantized massive scalar field in the global monopole spacetime I: the field fluctuation
27 pages, 3 figures
Phys. Rev. D 101, 125016 (2020)
10.1103/PhysRevD.101.125016
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study the vacuum polarization of a massive scalar field $\phi$ with arbitrary coupling to gravity in pointlike global monopole spacetime. Using Schwinger-DeWitt proper time formalism, we calculate the vacuum expectation value $<\phi^{2}>$, when the Compton length of the quantum field is much less than the characteristic radius of the curvature of the background geometry, and we can ignore nonlocal contributions. Explicit analytic expressions are obtained for a general curvature coupling parameter, and specified to the more physical cases of minimal and conformal coupling. Comparing the leading term of $<\phi^{2}>$, proportional to the coincident limit of the Hadamard-DeWitt coeficcient $a_{2}$, with higher order terms, that include the coincident limits of coefficients up to $a_{5}$, we conclude that the next to next to next to leading approximation need to be used to give a more precise description of vacuum polarization effects in this structures. We also find the trace of the renormalized stress energy tensor for the quantized field in the leading approximation, using the existing relationship between this magnitude, the trace anomaly and the field fluctuation.
[ { "created": "Thu, 4 Apr 2019 06:11:45 GMT", "version": "v1" } ]
2020-07-01
[ [ "Piedra", "Owen Pavel Fernández", "" ] ]
We study the vacuum polarization of a massive scalar field $\phi$ with arbitrary coupling to gravity in pointlike global monopole spacetime. Using Schwinger-DeWitt proper time formalism, we calculate the vacuum expectation value $<\phi^{2}>$, when the Compton length of the quantum field is much less than the characteristic radius of the curvature of the background geometry, and we can ignore nonlocal contributions. Explicit analytic expressions are obtained for a general curvature coupling parameter, and specified to the more physical cases of minimal and conformal coupling. Comparing the leading term of $<\phi^{2}>$, proportional to the coincident limit of the Hadamard-DeWitt coeficcient $a_{2}$, with higher order terms, that include the coincident limits of coefficients up to $a_{5}$, we conclude that the next to next to next to leading approximation need to be used to give a more precise description of vacuum polarization effects in this structures. We also find the trace of the renormalized stress energy tensor for the quantized field in the leading approximation, using the existing relationship between this magnitude, the trace anomaly and the field fluctuation.
1505.07479
Steffen Gielen
Steffen Gielen
Identifying cosmological perturbations in group field theory condensates
21 pages; v2: corrected minor typos, matches published version
JHEP 1508 (2015) 010
10.1007/JHEP08(2015)010
IMPERIAL-TP-2015-SG-1
gr-qc astro-ph.CO hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
One proposal for deriving effective cosmological models from theories of quantum gravity is to view the former as a mean-field (hydrodynamic) description of the latter, which describes a universe formed by a 'condensate' of quanta of geometry. This idea has been successfully applied within the setting of group field theory (GFT), a quantum field theory of 'atoms of space' which can form such a condensate. We further clarify the interpretation of this mean-field approximation, and show how it can be used to obtain a semiclassical description of the GFT, in which the mean field encodes a classical statistical distribution of geometric data. In this sense, GFT condensates are quantum homogeneous geometries that also contain statistical information about cosmological inhomogeneities. We show in the isotropic case how this information can be extracted from geometric GFT observables and mapped to quantities of observational interest. Basic uncertainty relations of (non-commutative) Fourier transforms imply that this statistical description can only be compatible with the observed near-homogeneity of the Universe if the typical length scale associated to the distribution is much larger than the fundamental 'Planck' scale. As an example of effective cosmological equations derived from the GFT dynamics, we then use a simple approximation in one class of GFT models to derive the 'improved dynamics' prescription of holonomy corrections in loop quantum cosmology.
[ { "created": "Wed, 27 May 2015 20:05:44 GMT", "version": "v1" }, { "created": "Mon, 3 Aug 2015 14:18:59 GMT", "version": "v2" } ]
2015-08-12
[ [ "Gielen", "Steffen", "" ] ]
One proposal for deriving effective cosmological models from theories of quantum gravity is to view the former as a mean-field (hydrodynamic) description of the latter, which describes a universe formed by a 'condensate' of quanta of geometry. This idea has been successfully applied within the setting of group field theory (GFT), a quantum field theory of 'atoms of space' which can form such a condensate. We further clarify the interpretation of this mean-field approximation, and show how it can be used to obtain a semiclassical description of the GFT, in which the mean field encodes a classical statistical distribution of geometric data. In this sense, GFT condensates are quantum homogeneous geometries that also contain statistical information about cosmological inhomogeneities. We show in the isotropic case how this information can be extracted from geometric GFT observables and mapped to quantities of observational interest. Basic uncertainty relations of (non-commutative) Fourier transforms imply that this statistical description can only be compatible with the observed near-homogeneity of the Universe if the typical length scale associated to the distribution is much larger than the fundamental 'Planck' scale. As an example of effective cosmological equations derived from the GFT dynamics, we then use a simple approximation in one class of GFT models to derive the 'improved dynamics' prescription of holonomy corrections in loop quantum cosmology.
0902.1268
Dmitri Vassiliev
Olga Chervova and Dmitri Vassiliev
Massless Dirac equation as a special case of Cosserat elasticity
Submitted to the proceedings of the International Conference on Recent Trends in Mathematical Sciences, Bahrain, 10-12 November 2008
Journal of the Association of Arab Universities for Basic and Applied Sciences, 2009, vol. 7, p. 25-42. (Proceedings of the International Conference on Recent Trends in Mathematical Sciences, Bahrain, 10-12 November 2008.)
null
null
gr-qc math.DG
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We suggest an alternative mathematical model for the massless neutrino. Consider an elastic continuum in 3-dimensional Euclidean space and assume that points of this continuum can experience no displacements, only rotations. This framework is a special case of the so-called Cosserat theory of elasticity. Rotations of points of the continuum are described by attaching to each point an orthonormal basis which gives a field of orthonormal bases called the coframe. As the dynamical variables (unknowns) of our theory we choose a coframe and a density. We write down a potential energy which is conformally invariant and then incorporate time in the standard Newtonian way, by subtracting kinetic energy. Finally, we rewrite the resulting nonlinear variational problem in terms of an unknown spinor field. We look for quasi-stationary solutions, i.e. solutions that harmonically oscillate in time. We prove that in the quasi-stationary setting our model is equivalent to a pair of massless Dirac equations. The crucial element of the proof is the observation that our Lagrangian admits a factorisation.
[ { "created": "Sat, 7 Feb 2009 19:54:21 GMT", "version": "v1" } ]
2010-07-20
[ [ "Chervova", "Olga", "" ], [ "Vassiliev", "Dmitri", "" ] ]
We suggest an alternative mathematical model for the massless neutrino. Consider an elastic continuum in 3-dimensional Euclidean space and assume that points of this continuum can experience no displacements, only rotations. This framework is a special case of the so-called Cosserat theory of elasticity. Rotations of points of the continuum are described by attaching to each point an orthonormal basis which gives a field of orthonormal bases called the coframe. As the dynamical variables (unknowns) of our theory we choose a coframe and a density. We write down a potential energy which is conformally invariant and then incorporate time in the standard Newtonian way, by subtracting kinetic energy. Finally, we rewrite the resulting nonlinear variational problem in terms of an unknown spinor field. We look for quasi-stationary solutions, i.e. solutions that harmonically oscillate in time. We prove that in the quasi-stationary setting our model is equivalent to a pair of massless Dirac equations. The crucial element of the proof is the observation that our Lagrangian admits a factorisation.
1405.7439
Jiliang Jing
Zehua Tian and Jiliang Jing
Distinguishing de Sitter universe from thermal Minkowski spacetime by Casimir-Polder-like force
11 pages
JHEP 07, (2014) 089
10.1007/JHEP07(2014)089
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We demonstrate that the static ground state atom, which interacts with a conformally coupled massless scalar field in the de Sitter invariant vacuum, can obtain a position-dependent energy-level shift and this shift could cause a Casimir-Polder-like force on it. Interestingly no such force arises on the inertial atom bathed in a thermal radiation in the Minkowski universe. Thus, although the energy-level shifts of the static atom for these two cases are structurally the same, whether the energy-level shift causes the Casimir-Polder-like force, in principle, could be as an indicator to distinguish de Sitter universe from the thermal Minkowski spacetime.
[ { "created": "Thu, 29 May 2014 02:04:34 GMT", "version": "v1" }, { "created": "Sun, 15 Jun 2014 02:09:51 GMT", "version": "v2" } ]
2015-06-19
[ [ "Tian", "Zehua", "" ], [ "Jing", "Jiliang", "" ] ]
We demonstrate that the static ground state atom, which interacts with a conformally coupled massless scalar field in the de Sitter invariant vacuum, can obtain a position-dependent energy-level shift and this shift could cause a Casimir-Polder-like force on it. Interestingly no such force arises on the inertial atom bathed in a thermal radiation in the Minkowski universe. Thus, although the energy-level shifts of the static atom for these two cases are structurally the same, whether the energy-level shift causes the Casimir-Polder-like force, in principle, could be as an indicator to distinguish de Sitter universe from the thermal Minkowski spacetime.
1901.04306
Kazuharu Bamba
G.G.L. Nashed and Kazuharu Bamba
Higher dimensional rotating black hole solutions in quadratic $f(R)$ gravitational theory and the conserved quantities
15 pages, 2 figures, version accepted for publication in Entropy
null
null
FU-PCG-55
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We explore the quadratic form of the $f(R)=R+bR^2$ gravitational theory to derive rotating $N$-dimensions black hole solutions with $a_i, i\geq 1$ rotation parameters. Here, $R$ is the Ricci scalar, and $b$ is the dimensional parameter. We assumed that the $N$-dimensional spacetime is static and has flat horizons with a zero curvature boundary. We investigated the physics of black holes by calculating the relations of physical quantities such as the horizon radius and mass. We also demonstrate that in the four-dimensional case,the higher-order curvature does not contribute to the black hole,i.e., black hole does not depend on the dimensional parameter $b$ whereas in the case of $N>4$, it depends on parameter $b$ owing to the contribution of the correction $R^2$ term. We analyze the conserved quantities, energy, and angular-momentum, of black hole solutions by applying the relocalization method. Additionally, we calculate the thermodynamic quantities such as temperature and entropy and examine the stability of black hole solutions locally and show that they have thermodynamic stability. Moreover, the calculations of entropy put a constraint on the parameter $b$ to be $b<\frac{1}{16\Lambda}$ to obtain a positive entropy.
[ { "created": "Wed, 9 Jan 2019 16:21:56 GMT", "version": "v1" }, { "created": "Mon, 18 Feb 2019 00:06:55 GMT", "version": "v2" }, { "created": "Wed, 10 Mar 2021 14:01:38 GMT", "version": "v3" } ]
2021-03-11
[ [ "Nashed", "G. G. L.", "" ], [ "Bamba", "Kazuharu", "" ] ]
We explore the quadratic form of the $f(R)=R+bR^2$ gravitational theory to derive rotating $N$-dimensions black hole solutions with $a_i, i\geq 1$ rotation parameters. Here, $R$ is the Ricci scalar, and $b$ is the dimensional parameter. We assumed that the $N$-dimensional spacetime is static and has flat horizons with a zero curvature boundary. We investigated the physics of black holes by calculating the relations of physical quantities such as the horizon radius and mass. We also demonstrate that in the four-dimensional case,the higher-order curvature does not contribute to the black hole,i.e., black hole does not depend on the dimensional parameter $b$ whereas in the case of $N>4$, it depends on parameter $b$ owing to the contribution of the correction $R^2$ term. We analyze the conserved quantities, energy, and angular-momentum, of black hole solutions by applying the relocalization method. Additionally, we calculate the thermodynamic quantities such as temperature and entropy and examine the stability of black hole solutions locally and show that they have thermodynamic stability. Moreover, the calculations of entropy put a constraint on the parameter $b$ to be $b<\frac{1}{16\Lambda}$ to obtain a positive entropy.
2012.08570
Astrid Eichhorn
Johanna N. Borissova and Astrid Eichhorn
Towards black-hole singularity-resolution in the Lorentzian gravitational path integral
18 pages plus references, 4 figures
null
null
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Quantum Gravity is expected to resolve the singularities of classical General Relativity. Based on destructive interference of singular spacetime-configurations in the path integral, we find that higher-order curvature terms may allow to resolve black-hole singularities both in the spherically symmetric and axisymmetric case. In contrast, the Einstein action does not provide a dynamical mechanism for singularity-resolution through destructive interference of these configurations.
[ { "created": "Tue, 15 Dec 2020 19:30:55 GMT", "version": "v1" } ]
2020-12-17
[ [ "Borissova", "Johanna N.", "" ], [ "Eichhorn", "Astrid", "" ] ]
Quantum Gravity is expected to resolve the singularities of classical General Relativity. Based on destructive interference of singular spacetime-configurations in the path integral, we find that higher-order curvature terms may allow to resolve black-hole singularities both in the spherically symmetric and axisymmetric case. In contrast, the Einstein action does not provide a dynamical mechanism for singularity-resolution through destructive interference of these configurations.
2208.01845
Fan Zhang
Fan Zhang, Lee Lindblom
Simple Numerical Solutions to the Einstein Constraints on Various Three-Manifolds
15 pages, 6 figures, published version
Gen Relativ Gravit 54, 131 (2022)
10.1007/s10714-022-03014-2
null
gr-qc
http://creativecommons.org/licenses/by/4.0/
Numerical solutions to the Einstein constraint equations are constructed on a selection of compact orientable three-dimensional manifolds with non-trivial topologies. A simple constant mean curvature solution and a somewhat more complicated non-constant mean curvature solution are computed on example manifolds from three of the eight Thursten geometrization classes. The constant mean curvature solutions found here are also solutions to the Yamabe problem that transforms a geometry into one with constant scalar curvature.
[ { "created": "Wed, 3 Aug 2022 05:06:23 GMT", "version": "v1" }, { "created": "Wed, 26 Oct 2022 01:24:10 GMT", "version": "v2" } ]
2022-10-27
[ [ "Zhang", "Fan", "" ], [ "Lindblom", "Lee", "" ] ]
Numerical solutions to the Einstein constraint equations are constructed on a selection of compact orientable three-dimensional manifolds with non-trivial topologies. A simple constant mean curvature solution and a somewhat more complicated non-constant mean curvature solution are computed on example manifolds from three of the eight Thursten geometrization classes. The constant mean curvature solutions found here are also solutions to the Yamabe problem that transforms a geometry into one with constant scalar curvature.
1105.3703
Norbert Bodendorfer
Norbert Bodendorfer, Thomas Thiemann, Andreas Thurn
New Variables for Classical and Quantum Gravity in all Dimensions I. Hamiltonian Analysis
28 pages. v2: Journal version. Minor clarifications
Class. Quantum Grav. 30 (2013) 045001
10.1088/0264-9381/30/4/045001
null
gr-qc hep-th math-ph math.MP
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Loop Quantum Gravity heavily relies on a connection formulation of General Relativity such that 1. the connection Poisson commutes with itself and 2. the corresponding gauge group is compact. This can be achieved starting from the Palatini or Holst action when imposing the time gauge. Unfortunately, this method is restricted to D+1 = 4 spacetime dimensions. However, interesting String theories and Supergravity theories require higher dimensions and it would therefore be desirable to have higher dimensional Supergravity loop quantisations at one's disposal in order to compare these approaches. In this series of papers, we take first steps towards this goal. The present first paper develops a classical canonical platform for a higher dimensional connection formulation of the purely gravitational sector. The new ingredient is a different extension of the ADM phase space than the one used in LQG, which does not require the time gauge and which generalises to any dimension D > 1. The result is a Yang-Mills theory phase space subject to Gauss, spatial diffeomorphism and Hamiltonian constraint as well as one additional constraint, called the simplicity constraint. The structure group can be chosen to be SO(1,D) or SO(D+1) and the latter choice is preferred for purposes of quantisation.
[ { "created": "Wed, 18 May 2011 18:24:56 GMT", "version": "v1" }, { "created": "Tue, 12 Feb 2013 18:38:00 GMT", "version": "v2" } ]
2013-02-13
[ [ "Bodendorfer", "Norbert", "" ], [ "Thiemann", "Thomas", "" ], [ "Thurn", "Andreas", "" ] ]
Loop Quantum Gravity heavily relies on a connection formulation of General Relativity such that 1. the connection Poisson commutes with itself and 2. the corresponding gauge group is compact. This can be achieved starting from the Palatini or Holst action when imposing the time gauge. Unfortunately, this method is restricted to D+1 = 4 spacetime dimensions. However, interesting String theories and Supergravity theories require higher dimensions and it would therefore be desirable to have higher dimensional Supergravity loop quantisations at one's disposal in order to compare these approaches. In this series of papers, we take first steps towards this goal. The present first paper develops a classical canonical platform for a higher dimensional connection formulation of the purely gravitational sector. The new ingredient is a different extension of the ADM phase space than the one used in LQG, which does not require the time gauge and which generalises to any dimension D > 1. The result is a Yang-Mills theory phase space subject to Gauss, spatial diffeomorphism and Hamiltonian constraint as well as one additional constraint, called the simplicity constraint. The structure group can be chosen to be SO(1,D) or SO(D+1) and the latter choice is preferred for purposes of quantisation.
1202.5708
Brendan McMonigal
Brendan McMonigal, Geraint F. Lewis, Philip O'Byrne
The Alcubierre Warp Drive: On the Matter of Matter
null
null
10.1103/PhysRevD.85.064024
null
gr-qc astro-ph.CO astro-ph.HE
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The Alcubierre warp drive allows a spaceship to travel at an arbitrarily large global velocity by deforming the spacetime in a bubble around the spaceship. Little is known about the interactions between massive particles and the Alcubierre warp drive, or the effects of an accelerating or decelerating warp bubble. We examine geodesics representative of the paths of null and massive particles with a range of initial velocities from -c to c interacting with an Alcubierre warp bubble travelling at a range of globally subluminal and superluminal velocities on both constant and variable velocity paths. The key results for null particles match what would be expected of massive test particles as they approach +/- c. The increase in energy for massive and null particles is calculated in terms of v_s, the global ship velocity, and v_p, the initial velocity of the particle with respect to the rest frame of the origin/destination of the ship. Particles with positive v_p obtain extremely high energy and velocity and become "time locked" for the duration of their time in the bubble, experiencing very little proper time between entering and eventually leaving the bubble. When interacting with an accelerating bubble, any particles within the bubble at the time receive a velocity boost that increases or decreases the magnitude of their velocity if the particle is moving towards the front or rear of the bubble respectively. If the bubble is decelerating, the opposite effect is observed. Thus Eulerian matter is unaffected by bubble accelerations/decelerations. The magnitude of the velocity boosts scales with the magnitude of the bubble acceleration/deceleration.
[ { "created": "Sun, 26 Feb 2012 00:57:15 GMT", "version": "v1" } ]
2015-06-04
[ [ "McMonigal", "Brendan", "" ], [ "Lewis", "Geraint F.", "" ], [ "O'Byrne", "Philip", "" ] ]
The Alcubierre warp drive allows a spaceship to travel at an arbitrarily large global velocity by deforming the spacetime in a bubble around the spaceship. Little is known about the interactions between massive particles and the Alcubierre warp drive, or the effects of an accelerating or decelerating warp bubble. We examine geodesics representative of the paths of null and massive particles with a range of initial velocities from -c to c interacting with an Alcubierre warp bubble travelling at a range of globally subluminal and superluminal velocities on both constant and variable velocity paths. The key results for null particles match what would be expected of massive test particles as they approach +/- c. The increase in energy for massive and null particles is calculated in terms of v_s, the global ship velocity, and v_p, the initial velocity of the particle with respect to the rest frame of the origin/destination of the ship. Particles with positive v_p obtain extremely high energy and velocity and become "time locked" for the duration of their time in the bubble, experiencing very little proper time between entering and eventually leaving the bubble. When interacting with an accelerating bubble, any particles within the bubble at the time receive a velocity boost that increases or decreases the magnitude of their velocity if the particle is moving towards the front or rear of the bubble respectively. If the bubble is decelerating, the opposite effect is observed. Thus Eulerian matter is unaffected by bubble accelerations/decelerations. The magnitude of the velocity boosts scales with the magnitude of the bubble acceleration/deceleration.
gr-qc/9505022
Karen Brewster
Lee Smolin
Cosmology as a Problem in Critical Phenomena
52 pages, Latex File, No Figures
null
10.1007/BFb0103573
CGPG-95/5-2, IASSNS-95/30
gr-qc astro-ph
null
Several problems in cosmology and astrophysics are described in which critical phenomena of various types may play a role. These include the organization of the disks of spiral galaxies, various aspects of the problem of structure formation in icosmology, the problem of the selection of initial conditions and parameters in particle physics and cosmology and the problem of recovering the classical limit from non-perturbative formulations of quantum gravity.
[ { "created": "Tue, 16 May 1995 15:37:02 GMT", "version": "v1" } ]
2009-10-28
[ [ "Smolin", "Lee", "" ] ]
Several problems in cosmology and astrophysics are described in which critical phenomena of various types may play a role. These include the organization of the disks of spiral galaxies, various aspects of the problem of structure formation in icosmology, the problem of the selection of initial conditions and parameters in particle physics and cosmology and the problem of recovering the classical limit from non-perturbative formulations of quantum gravity.
gr-qc/9710024
Malcolm MacCallum
M.A.H. MacCallum
Hypersurface-orthogonal generators of an orthogonally transitive transitive $G_2I$, topological identifications, and axially and cylindrically symmetric spacetimes
16 pages, latex 2.09, no figures. Accepted for publication in General Relativity and Gravitation
Gen.Rel.Grav.30:131-150,1998
10.1023/A:1018833219068
null
gr-qc
null
A criterion given by Castejon-Amenedo and MacCallum (1990) for the existence of (locally) hypersurface-orthogonal generators of an orthogonally-transitive two-parameter Abelian group of motions (a $G_2I$) in spacetime is re-expressed as a test for linear dependence with constant coefficients between the three components of the metric in the orbits in canonical coordinates. In general, it is shown that such a relation implies that the metric is locally diagonalizable in canonical coordinates, or has a null Killing vector, or can locally be written in a generalized form of the `windmill' solutions characterized by McIntosh. If the orbits of the $G_2I$ have cylindrical or toroidal topology and a periodic coordinate is used, these metric forms cannot in general be realized globally as they would conflict with the topological identification. The geometry then has additional essential parameters, which specify the topological identification. The physical significance of these parameters is shown by their appearance in global holonomy and by examples of exterior solutions where they have been related to characteristics of physical sources. These results lead to some remarks about the definition of cylindrical symmetry.
[ { "created": "Fri, 3 Oct 1997 13:46:58 GMT", "version": "v1" } ]
2008-11-26
[ [ "MacCallum", "M. A. H.", "" ] ]
A criterion given by Castejon-Amenedo and MacCallum (1990) for the existence of (locally) hypersurface-orthogonal generators of an orthogonally-transitive two-parameter Abelian group of motions (a $G_2I$) in spacetime is re-expressed as a test for linear dependence with constant coefficients between the three components of the metric in the orbits in canonical coordinates. In general, it is shown that such a relation implies that the metric is locally diagonalizable in canonical coordinates, or has a null Killing vector, or can locally be written in a generalized form of the `windmill' solutions characterized by McIntosh. If the orbits of the $G_2I$ have cylindrical or toroidal topology and a periodic coordinate is used, these metric forms cannot in general be realized globally as they would conflict with the topological identification. The geometry then has additional essential parameters, which specify the topological identification. The physical significance of these parameters is shown by their appearance in global holonomy and by examples of exterior solutions where they have been related to characteristics of physical sources. These results lead to some remarks about the definition of cylindrical symmetry.
1802.03577
Kaifeng Cui
Liangsuo Shu, Kaifeng Cui, Xiaokang Liu, Zhichun Liu, Wei Liu
Surface tension of the horizon
12 Pages, 1 figures
Fortschritte der Physik 67(3): 1800076 (2019)
10.1002/prop.201800076
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The idea of treating the horizon of a black hole as a stretched membrane with surface tension has a long history. In this work, we discuss the microscopic origin of the surface tension of the horizon in quantum pictures of spaces, which are Bose-Einstein condensates of gravitons. The horizon is a phase interface of gravitons, the surface tension of which is found to be a result of the difference in the strength of the interaction between the gravitons on its two sides. The gravitational source, such as a Schwarzschild black hole, creates a transitional zone by changing the energy and distribution of its surrounding gravitons. Archimedes' principle for gravity can be expressed as follows: "the gravity on an object is equal to the weight of the gravitons that it displaces."
[ { "created": "Sat, 10 Feb 2018 12:46:22 GMT", "version": "v1" }, { "created": "Sat, 5 May 2018 06:55:43 GMT", "version": "v2" }, { "created": "Sun, 24 Jun 2018 14:53:40 GMT", "version": "v3" }, { "created": "Fri, 25 Jan 2019 02:34:42 GMT", "version": "v4" } ]
2022-03-25
[ [ "Shu", "Liangsuo", "" ], [ "Cui", "Kaifeng", "" ], [ "Liu", "Xiaokang", "" ], [ "Liu", "Zhichun", "" ], [ "Liu", "Wei", "" ] ]
The idea of treating the horizon of a black hole as a stretched membrane with surface tension has a long history. In this work, we discuss the microscopic origin of the surface tension of the horizon in quantum pictures of spaces, which are Bose-Einstein condensates of gravitons. The horizon is a phase interface of gravitons, the surface tension of which is found to be a result of the difference in the strength of the interaction between the gravitons on its two sides. The gravitational source, such as a Schwarzschild black hole, creates a transitional zone by changing the energy and distribution of its surrounding gravitons. Archimedes' principle for gravity can be expressed as follows: "the gravity on an object is equal to the weight of the gravitons that it displaces."
2206.14787
Dominik Szcz\c{e}\'sniak PhD
Adam Z. Kaczmarek, Dominik Szcz\c{e}\'sniak, Sabre Kais
Measurement-induced nonlocality for observers near a black hole
4 figures
null
null
null
gr-qc quant-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We present a systematic and complementary study of quantum correlations near a black hole by considering the measurement-induced nonlocality (MIN). The quantum measure of interest is discussed on the same footing for the fermionic, bosonic and mixed fermion-boson modes in relation to the Hawking radiation. The obtained results show that in the infinite Hawking temperature limit, the physically accessible correlations does not vanish only in the fermionic case. However, the higher frequency modes can sustain correlations for the finite Hawking temperature, with mixed system being more sensitive towards increase of the fermionic frequencies than the bosonic ones. Since the MIN for the latter modes quickly diminishes, the increased frequency may be a way to maintain nonlocal correlations for the scenarios at the finite Hawking temperature.
[ { "created": "Wed, 29 Jun 2022 17:41:49 GMT", "version": "v1" }, { "created": "Thu, 9 Mar 2023 19:07:38 GMT", "version": "v2" } ]
2023-03-13
[ [ "Kaczmarek", "Adam Z.", "" ], [ "Szczȩśniak", "Dominik", "" ], [ "Kais", "Sabre", "" ] ]
We present a systematic and complementary study of quantum correlations near a black hole by considering the measurement-induced nonlocality (MIN). The quantum measure of interest is discussed on the same footing for the fermionic, bosonic and mixed fermion-boson modes in relation to the Hawking radiation. The obtained results show that in the infinite Hawking temperature limit, the physically accessible correlations does not vanish only in the fermionic case. However, the higher frequency modes can sustain correlations for the finite Hawking temperature, with mixed system being more sensitive towards increase of the fermionic frequencies than the bosonic ones. Since the MIN for the latter modes quickly diminishes, the increased frequency may be a way to maintain nonlocal correlations for the scenarios at the finite Hawking temperature.
2304.04802
Warren Li
Warren Li
Kasner-like description of spacelike singularities in spherically symmetric spacetimes with scalar matter
65 pages, 12 figures, comments welcome!
null
null
null
gr-qc math.AP math.DG
http://creativecommons.org/licenses/by/4.0/
We study the properties of spacelike singularities in spherically symmetric spacetimes obeying the Einstein equations, in the presence of matter. We consider in particular matter described by a scalar field, both in the presence of an electromagnetic field and without. We prove that if a spacelike singularity obeying several reasonable assumptions is formed, then the Hawking mass, the Kretschmann scalar, and the matter fields have inverse polynomial blow-up rates near the singularity that may be described precisely. Furthermore, one may view the resulting spacetime in the context of the BKL heuristics regarding space-like singularities in relativistic cosmology. In particular, near any point $p$ on the singular boundary in our spherically symmetric spacetime, we obtain a leading order BKL-type expansion, including a description of Kasner exponents associated to $p$. This provides a rigorous description of a detailed correspondence between Kasner-like singularities most often associated to the cosmological setting, and the singularities observed in (spherically symmetric) gravitational collapse. Moreover, we outline a program concerning the study of the stability and instability of spacelike singularities in the latter picture, both outside of spherical symmetry and within (where the electromagnetic field acts as a proxy for angular momentum) - in particular we signify the importance of cosmological phenomena including subcritical regimes and Kasner bounces in the collapse setting.
[ { "created": "Mon, 10 Apr 2023 18:21:34 GMT", "version": "v1" } ]
2023-04-12
[ [ "Li", "Warren", "" ] ]
We study the properties of spacelike singularities in spherically symmetric spacetimes obeying the Einstein equations, in the presence of matter. We consider in particular matter described by a scalar field, both in the presence of an electromagnetic field and without. We prove that if a spacelike singularity obeying several reasonable assumptions is formed, then the Hawking mass, the Kretschmann scalar, and the matter fields have inverse polynomial blow-up rates near the singularity that may be described precisely. Furthermore, one may view the resulting spacetime in the context of the BKL heuristics regarding space-like singularities in relativistic cosmology. In particular, near any point $p$ on the singular boundary in our spherically symmetric spacetime, we obtain a leading order BKL-type expansion, including a description of Kasner exponents associated to $p$. This provides a rigorous description of a detailed correspondence between Kasner-like singularities most often associated to the cosmological setting, and the singularities observed in (spherically symmetric) gravitational collapse. Moreover, we outline a program concerning the study of the stability and instability of spacelike singularities in the latter picture, both outside of spherical symmetry and within (where the electromagnetic field acts as a proxy for angular momentum) - in particular we signify the importance of cosmological phenomena including subcritical regimes and Kasner bounces in the collapse setting.
1509.03698
Francisco Frutos-Alfaro Dr. rer. nat.
Francisco Frutos-Alfaro
Approximate Kerr-like Metric with Quadrupole
null
International Journal of Astronomy and Astrophysics, 6, 334-345, 2016
10.4236/ijaa.2016.63028.
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
A new approximate metric representing the spacetime of a rotating deformed body is obtained by perturbing the Kerr metric to include til the second order of the quadrupole moment. It has a simple form, because is Kerr-like. Its Taylor expansion form coincides with second order quadrupole metrics with slow rotation already found. Moreover, it can be transformed to an improved Hartle-Thorne metric, this guarantees its validity to be useful in studying compact object, and that it is possible to find an inner solution.
[ { "created": "Sat, 12 Sep 2015 02:59:24 GMT", "version": "v1" }, { "created": "Thu, 29 Nov 2018 17:08:09 GMT", "version": "v10" }, { "created": "Thu, 17 Sep 2015 01:18:37 GMT", "version": "v2" }, { "created": "Thu, 8 Oct 2015 15:30:03 GMT", "version": "v3" }, { "created": "Mon, 29 Aug 2016 23:58:29 GMT", "version": "v4" }, { "created": "Tue, 4 Oct 2016 04:41:58 GMT", "version": "v5" }, { "created": "Wed, 8 Nov 2017 23:15:10 GMT", "version": "v6" }, { "created": "Fri, 5 Jan 2018 04:55:24 GMT", "version": "v7" }, { "created": "Thu, 1 Feb 2018 05:15:52 GMT", "version": "v8" }, { "created": "Mon, 5 Feb 2018 15:04:02 GMT", "version": "v9" } ]
2018-11-30
[ [ "Frutos-Alfaro", "Francisco", "" ] ]
A new approximate metric representing the spacetime of a rotating deformed body is obtained by perturbing the Kerr metric to include til the second order of the quadrupole moment. It has a simple form, because is Kerr-like. Its Taylor expansion form coincides with second order quadrupole metrics with slow rotation already found. Moreover, it can be transformed to an improved Hartle-Thorne metric, this guarantees its validity to be useful in studying compact object, and that it is possible to find an inner solution.
0907.5104
Carlos A. R. Herdeiro
Carlos A. R. Herdeiro, Carmen Rebelo and Claude M. Warnick
On the backreaction of frame dragging
18 pages, 8 figures
null
10.1103/PhysRevD.80.084037
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The backreaction on black holes due to dragging heavy, rather than test, objects is discussed. As a case study, a regular black Saturn system where the central black hole has vanishing intrinsic angular momentum, J^{BH}=0, is considered. It is shown that there is a correlation between the sign of two response functions. One is interpreted as a moment of inertia of the black ring in the black Saturn system. The other measures the variation of the black ring horizon angular velocity with the central black hole mass, for fixed ring mass and angular momentum. The two different phases defined by these response functions collapse, for small central black hole mass, to the thin and fat ring phases. In the fat phase, the zero area limit of the black Saturn ring has reduced spin j^2>1, which is related to the behaviour of the ring angular velocity. Using the `gravitomagnetic clock effect', for which a universality property is exhibited, it is shown that frame dragging measured by an asymptotic observer decreases, in both phases, when the central black hole mass increases, for fixed ring mass and angular momentum. A close parallelism between the results for the fat phase and those obtained recently for the double Kerr solution is drawn, considering also a regular black Saturn system with J^{BH}\neq 0.
[ { "created": "Wed, 29 Jul 2009 10:58:45 GMT", "version": "v1" } ]
2013-05-29
[ [ "Herdeiro", "Carlos A. R.", "" ], [ "Rebelo", "Carmen", "" ], [ "Warnick", "Claude M.", "" ] ]
The backreaction on black holes due to dragging heavy, rather than test, objects is discussed. As a case study, a regular black Saturn system where the central black hole has vanishing intrinsic angular momentum, J^{BH}=0, is considered. It is shown that there is a correlation between the sign of two response functions. One is interpreted as a moment of inertia of the black ring in the black Saturn system. The other measures the variation of the black ring horizon angular velocity with the central black hole mass, for fixed ring mass and angular momentum. The two different phases defined by these response functions collapse, for small central black hole mass, to the thin and fat ring phases. In the fat phase, the zero area limit of the black Saturn ring has reduced spin j^2>1, which is related to the behaviour of the ring angular velocity. Using the `gravitomagnetic clock effect', for which a universality property is exhibited, it is shown that frame dragging measured by an asymptotic observer decreases, in both phases, when the central black hole mass increases, for fixed ring mass and angular momentum. A close parallelism between the results for the fat phase and those obtained recently for the double Kerr solution is drawn, considering also a regular black Saturn system with J^{BH}\neq 0.
2008.00659
Josef Kluson
J. Kluson, B. Matous
Covariant Hamiltonian Formalism for F(R)-Gravity
12 pages,v2:references added
null
null
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this short note we perform covariant Hamiltonian analysis of F(R)-gravity.
[ { "created": "Mon, 3 Aug 2020 05:59:47 GMT", "version": "v1" }, { "created": "Tue, 18 Aug 2020 07:24:36 GMT", "version": "v2" } ]
2020-08-19
[ [ "Kluson", "J.", "" ], [ "Matous", "B.", "" ] ]
In this short note we perform covariant Hamiltonian analysis of F(R)-gravity.
1606.01509
Christian R\"oken
Felix Finster and Christian R\"oken
An Integral Spectral Representation of the Massive Dirac Propagator in the Kerr Geometry in Eddington-Finkelstein-type Coordinates
31 pages, 1 figure, details added, references added, minor corrections
Adv.Theor.Math.Phys. 22 (2018) 47-92
10.4310/ATMP.2018.v22.n1.a3
null
gr-qc math-ph math.MP
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We consider the massive Dirac equation in the non-extreme Kerr geometry in horizon-penetrating advanced Eddington-Finkelstein-type coordinates and derive a functional analytic integral representation of the associated propagator using the spectral theorem for unbounded self-adjoint operators, Stone's formula, and quantities arising in the analysis of Chandrasekhar's separation of variables. This integral representation describes the dynamics of Dirac particles outside and across the event horizon, up to the Cauchy horizon. In the derivation, we first write the Dirac equation in Hamiltonian form and show the essential self-adjointness of the Hamiltonian. For the latter purpose, as the Dirac Hamiltonian fails to be elliptic at the event and the Cauchy horizon, we cannot use standard elliptic methods of proof. Instead, we employ a new, general method for mixed initial-boundary value problems that combines results from the theory of symmetric hyperbolic systems with near-boundary elliptic methods. In this regard and since the time evolution may not be unitary because of Dirac particles impinging on the ring singularity, we also impose a suitable Dirichlet-type boundary condition on a time-like inner hypersurface placed inside the Cauchy horizon, which has no effect on the dynamics outside the Cauchy horizon. We then compute the resolvent of the Dirac Hamiltonian via the projector onto a finite-dimensional, invariant spectral eigenspace of the angular operator and the radial Green's matrix stemming from Chandrasekhar's separation of variables. Applying Stone's formula to the spectral measure of the Hamiltonian in the spectral decomposition of the Dirac propagator, that is, by expressing the spectral measure in terms of this resolvent, we obtain an explicit integral representation of the propagator.
[ { "created": "Sun, 5 Jun 2016 13:50:35 GMT", "version": "v1" }, { "created": "Thu, 2 Nov 2017 12:00:28 GMT", "version": "v2" }, { "created": "Fri, 31 Aug 2018 10:41:35 GMT", "version": "v3" } ]
2020-08-13
[ [ "Finster", "Felix", "" ], [ "Röken", "Christian", "" ] ]
We consider the massive Dirac equation in the non-extreme Kerr geometry in horizon-penetrating advanced Eddington-Finkelstein-type coordinates and derive a functional analytic integral representation of the associated propagator using the spectral theorem for unbounded self-adjoint operators, Stone's formula, and quantities arising in the analysis of Chandrasekhar's separation of variables. This integral representation describes the dynamics of Dirac particles outside and across the event horizon, up to the Cauchy horizon. In the derivation, we first write the Dirac equation in Hamiltonian form and show the essential self-adjointness of the Hamiltonian. For the latter purpose, as the Dirac Hamiltonian fails to be elliptic at the event and the Cauchy horizon, we cannot use standard elliptic methods of proof. Instead, we employ a new, general method for mixed initial-boundary value problems that combines results from the theory of symmetric hyperbolic systems with near-boundary elliptic methods. In this regard and since the time evolution may not be unitary because of Dirac particles impinging on the ring singularity, we also impose a suitable Dirichlet-type boundary condition on a time-like inner hypersurface placed inside the Cauchy horizon, which has no effect on the dynamics outside the Cauchy horizon. We then compute the resolvent of the Dirac Hamiltonian via the projector onto a finite-dimensional, invariant spectral eigenspace of the angular operator and the radial Green's matrix stemming from Chandrasekhar's separation of variables. Applying Stone's formula to the spectral measure of the Hamiltonian in the spectral decomposition of the Dirac propagator, that is, by expressing the spectral measure in terms of this resolvent, we obtain an explicit integral representation of the propagator.
2311.16934
Andrea Pierfrancesco Sanna
Mariano Cadoni, Mauro Oi, Mirko Pitzalis, Andrea P. Sanna
Scalar stars and lumps with (A)dS core
26 pages, 5 figures, 1 appendix
null
null
null
gr-qc hep-th
http://creativecommons.org/licenses/by/4.0/
We explore the possibility of embedding regular compact objects with (anti) de Sitter ((A)dS) core as solutions of Einstein's gravity minimally coupled to a real scalar field. We consider, among others, solutions interpolating between an inner, potential-dominated core and an outer, kinetic-term-dominated region. Owing to their analogy with slow-roll inflation, we term them gravitational vacuum inflative stars, or gravistars for short. We systematically discuss approximate solutions of the theory describing either the core or the asymptotically-flat region at spatial infinity. We extend nonexistence theorems for smooth interpolating solutions, previously proved for black holes, to compact objects without event horizons. This allows us to construct different classes of exact (either smooth or non-smooth) singularity-free solutions of the theory. We first find a smooth solution interpolating between an AdS spacetime in the core and an asymptotically-flat spacetime (a Schwarzschild solution with a subleading $1/r^2$ deformation). We proceed by constructing non-smooth solutions describing gravistars. Finally, we derive a smooth scalar lump solution interpolating between $\text{AdS}_4$ in the core and a Nariai spacetime at spatial infinity.
[ { "created": "Tue, 28 Nov 2023 16:34:57 GMT", "version": "v1" } ]
2023-11-29
[ [ "Cadoni", "Mariano", "" ], [ "Oi", "Mauro", "" ], [ "Pitzalis", "Mirko", "" ], [ "Sanna", "Andrea P.", "" ] ]
We explore the possibility of embedding regular compact objects with (anti) de Sitter ((A)dS) core as solutions of Einstein's gravity minimally coupled to a real scalar field. We consider, among others, solutions interpolating between an inner, potential-dominated core and an outer, kinetic-term-dominated region. Owing to their analogy with slow-roll inflation, we term them gravitational vacuum inflative stars, or gravistars for short. We systematically discuss approximate solutions of the theory describing either the core or the asymptotically-flat region at spatial infinity. We extend nonexistence theorems for smooth interpolating solutions, previously proved for black holes, to compact objects without event horizons. This allows us to construct different classes of exact (either smooth or non-smooth) singularity-free solutions of the theory. We first find a smooth solution interpolating between an AdS spacetime in the core and an asymptotically-flat spacetime (a Schwarzschild solution with a subleading $1/r^2$ deformation). We proceed by constructing non-smooth solutions describing gravistars. Finally, we derive a smooth scalar lump solution interpolating between $\text{AdS}_4$ in the core and a Nariai spacetime at spatial infinity.
0804.1007
Alicia M. Sintes
Llucia Sancho de la Jordana and Alicia M. Sintes
A $\chi^2$ veto for continuous gravitational wave searches
Final version, 12th Gravitational Waves Data Analysis Workshop
Class.Quant.Grav.25:184014,2008
10.1088/0264-9381/25/18/184014
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
$\chi^2$ vetoes are commonly used in searching for gravitational waves, in particular for broad-band signals, but they can also be applied to narrow-band continuous wave signals, such as those expected from rapidly rotating neutron stars. In this paper we present a $\chi^2$ veto adapted to the Hough transform searches for continuous gravitational wave signals; we characterize the $\chi^2$-significance plane for different frequency bands; and discuss the expected performance of this veto in LIGO analysis.
[ { "created": "Mon, 7 Apr 2008 11:19:24 GMT", "version": "v1" }, { "created": "Fri, 27 Feb 2009 14:50:49 GMT", "version": "v2" } ]
2009-03-09
[ [ "de la Jordana", "Llucia Sancho", "" ], [ "Sintes", "Alicia M.", "" ] ]
$\chi^2$ vetoes are commonly used in searching for gravitational waves, in particular for broad-band signals, but they can also be applied to narrow-band continuous wave signals, such as those expected from rapidly rotating neutron stars. In this paper we present a $\chi^2$ veto adapted to the Hough transform searches for continuous gravitational wave signals; we characterize the $\chi^2$-significance plane for different frequency bands; and discuss the expected performance of this veto in LIGO analysis.
1504.02686
Ott Vilson
Laur Jarv, Piret Kuusk, Margus Saal and Ott Vilson
Transformation properties and general relativity regime in scalar-tensor theories
34 pages, some references added and updated, a few sentences clarified
Class. Quantum Grav. 32, 235013 (2015)
10.1088/0264-9381/32/23/235013
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We consider first generation scalar-tensor theories of gravitation in a completely generic form, keeping the transformation functions of the local rescaling of the metric and the scalar field redefinition explicitly distinct from the coupling functions in the action. It is well known that in the Jordan frame Brans-Dicke type parametrization the diverging kinetic coupling function $\omega \rightarrow \infty$ can lead to the general relativity regime, however then the transformation functions to other parametrizations typically become singular, possibly spoiling the correspondence between different parametrizations. We give a detailed analysis of the transformation properties of the field equations with arbitrary metric and also in the Friedmann cosmology, and provide sufficient conditions under which the correspondence between different parametrizations is retained, even if the transformation is singular. It is interesting to witness the invariance of the notion of the general relativity regime and the correspondence of the perturbed cosmological equations as well as their solutions in different parametrizations, despite the fact that in some cases the perturbed equation turns out to be linear in one parametrization and nonlinear in some other.
[ { "created": "Fri, 10 Apr 2015 14:12:42 GMT", "version": "v1" }, { "created": "Fri, 13 Nov 2015 12:42:46 GMT", "version": "v2" } ]
2015-11-16
[ [ "Jarv", "Laur", "" ], [ "Kuusk", "Piret", "" ], [ "Saal", "Margus", "" ], [ "Vilson", "Ott", "" ] ]
We consider first generation scalar-tensor theories of gravitation in a completely generic form, keeping the transformation functions of the local rescaling of the metric and the scalar field redefinition explicitly distinct from the coupling functions in the action. It is well known that in the Jordan frame Brans-Dicke type parametrization the diverging kinetic coupling function $\omega \rightarrow \infty$ can lead to the general relativity regime, however then the transformation functions to other parametrizations typically become singular, possibly spoiling the correspondence between different parametrizations. We give a detailed analysis of the transformation properties of the field equations with arbitrary metric and also in the Friedmann cosmology, and provide sufficient conditions under which the correspondence between different parametrizations is retained, even if the transformation is singular. It is interesting to witness the invariance of the notion of the general relativity regime and the correspondence of the perturbed cosmological equations as well as their solutions in different parametrizations, despite the fact that in some cases the perturbed equation turns out to be linear in one parametrization and nonlinear in some other.
2105.06257
Joao Ider Silva Junior
Jo\~ao Ider
Evolution of matter fields in black holes with Lifshitz symmetry
Master dissertation (in Portuguese), Advisor: Prof. Dr. Alan Pavan, 117 pages, 37 figures
null
null
null
gr-qc
http://creativecommons.org/licenses/by/4.0/
In this work the evolution of two fields of matter in planar symmetric black holes D-dimensional with symmetry of Lifshitz whose dynamic exponent is $z$ were analyzed. The fields investigated were a scalar field non-minimal coupled to the Einstein tensor and the Ricci scalar and the electromagnetic field. Two black holes were chosen, one with 5-dimensions and z=1 and another with 6-dimensions and $z=0$. The equations of motion for both fields were developed in general and applied to each black hole mentioned. In some cases exact solutions of the equations were obtained in terms of hypergeometric functions and confluent Heun functions. The quasinormal modes (MQN) of evolution of the analyzed fields were calculated numerically using two different approaches: HH and AIM. In all the black holes studied the NSM's did not indicate instabilities neither regarding the couplings nor the space-times. In general, the quasinormal modes behave like the oscillation modes of a damped harmonic oscillator, presenting three regimes: underdamped $(\omega_R \neq0, \omega_I <0) $, critically damped $ (\omega_R=0,\omega_I^{crit} <0) $ and overdamped $ (\omega_R=0,\omega_I <0) $. In the analyzed cases an interesting behavior was found for $\omega_I $ when $ k \neq0 $ and $ r_+<10 $. In general, $\omega_I $ increase with $k$, but here we find a quadratic growth for $ k\sim r_+$ and then a decrease when $k>>r_+$. This behavior may be relevant in the context of gravity/gauge duality. Additionally, we also analyzed the evolution of the same fields in two black holes with symmetry of Lifshtiz in $ 2 + 1 $ dimensions.
[ { "created": "Tue, 11 May 2021 16:38:52 GMT", "version": "v1" } ]
2021-05-14
[ [ "Ider", "João", "" ] ]
In this work the evolution of two fields of matter in planar symmetric black holes D-dimensional with symmetry of Lifshitz whose dynamic exponent is $z$ were analyzed. The fields investigated were a scalar field non-minimal coupled to the Einstein tensor and the Ricci scalar and the electromagnetic field. Two black holes were chosen, one with 5-dimensions and z=1 and another with 6-dimensions and $z=0$. The equations of motion for both fields were developed in general and applied to each black hole mentioned. In some cases exact solutions of the equations were obtained in terms of hypergeometric functions and confluent Heun functions. The quasinormal modes (MQN) of evolution of the analyzed fields were calculated numerically using two different approaches: HH and AIM. In all the black holes studied the NSM's did not indicate instabilities neither regarding the couplings nor the space-times. In general, the quasinormal modes behave like the oscillation modes of a damped harmonic oscillator, presenting three regimes: underdamped $(\omega_R \neq0, \omega_I <0) $, critically damped $ (\omega_R=0,\omega_I^{crit} <0) $ and overdamped $ (\omega_R=0,\omega_I <0) $. In the analyzed cases an interesting behavior was found for $\omega_I $ when $ k \neq0 $ and $ r_+<10 $. In general, $\omega_I $ increase with $k$, but here we find a quadratic growth for $ k\sim r_+$ and then a decrease when $k>>r_+$. This behavior may be relevant in the context of gravity/gauge duality. Additionally, we also analyzed the evolution of the same fields in two black holes with symmetry of Lifshtiz in $ 2 + 1 $ dimensions.
gr-qc/0205004
David Langlois
David Langlois (IAP, Paris)
Gravitational and cosmological properties of a brane-universe
Review talk, Journees relativistes, Dublin (2001); 4 pages; Latex (with ws-ijmpa.cls); no figure
Int.J.Mod.Phys. A17 (2002) 2701-2706
10.1142/S0217751X02011631
null
gr-qc astro-ph hep-ph hep-th
null
The aim of this contribution is to provide a short introduction to recently investigated models in which our accessible universe is a four-dimensional submanifold, or brane, embedded in a higher dimensional spacetime and ordinary matter is trapped in the brane. I focus here on the gravitational and cosmological aspects of such models with a single extra-dimension.
[ { "created": "Wed, 1 May 2002 16:25:24 GMT", "version": "v1" } ]
2009-11-07
[ [ "Langlois", "David", "", "IAP, Paris" ] ]
The aim of this contribution is to provide a short introduction to recently investigated models in which our accessible universe is a four-dimensional submanifold, or brane, embedded in a higher dimensional spacetime and ordinary matter is trapped in the brane. I focus here on the gravitational and cosmological aspects of such models with a single extra-dimension.
0706.2736
Nikolai V. Mitskievich
N.V. Mitskievich, V.N. Efremov, and A.M. Hern\'andez Magdaleno
Topological gravitation on graph manifolds
3 pages, a talk delivered at the 11th Marcel Grossmann Meeting (2006)
null
10.1142/9789812834300_0265
null
gr-qc
null
A model of topological field theory is presented in which the vacuum coupling constants are topological invariants of the four-dimensional spacetime. Thus the coupling constants are theoretically computable, and they indicate the topological structure of our universe.
[ { "created": "Tue, 19 Jun 2007 08:55:58 GMT", "version": "v1" } ]
2016-11-15
[ [ "Mitskievich", "N. V.", "" ], [ "Efremov", "V. N.", "" ], [ "Magdaleno", "A. M. Hernández", "" ] ]
A model of topological field theory is presented in which the vacuum coupling constants are topological invariants of the four-dimensional spacetime. Thus the coupling constants are theoretically computable, and they indicate the topological structure of our universe.
1209.6533
Thomas Dent
The LIGO Scientific Collaboration and the Virgo Collaboration: J. Aasi, J. Abadie, B. P. Abbott, R. Abbott, T. D. Abbott, M. Abernathy, T. Accadia, F. Acernese, C. Adams, T. Adams, P. Addesso, R. Adhikari, C. Affeldt, M. Agathos, K. Agatsuma, P. Ajith, B. Allen, A. Allocca, E. Amador Ceron, D. Amariutei, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, S. Ast, S. M. Aston, P. Astone, D. Atkinson, P. Aufmuth, C. Aulbert, B. E. Aylott, S. Babak, P. Baker, G. Ballardin, S. Ballmer, Y. Bao, J. C. B. Barayoga, D. Barker, F. Barone, B. Barr, L. Barsotti, M. Barsuglia, M. A. Barton, I. Bartos, R. Bassiri, M. Bastarrika, A. Basti, J. Batch, J. Bauchrowitz, Th. S. Bauer, M. Bebronne, D. Beck, B. Behnke, M. Bejger, M.G. Beker, A. S. Bell, C. Bell, I. Belopolski, M. Benacquista, J. M. Berliner, A. Bertolini, J. Betzwieser, N. Beveridge, P. T. Beyersdorf, T. Bhadbade, I. A. Bilenko, G. Billingsley, J. Birch, R. Biswas, M. Bitossi, M. A. Bizouard, E. Black, J. K. Blackburn, L. Blackburn, D. Blair, B. Bland, M. Blom, O. Bock, T. P. Bodiya, C. Bogan, C. Bond, R. Bondarescu, F. Bondu, L. Bonelli, R. Bonnand, R. Bork, M. Born, V. Boschi, S. Bose, L. Bosi, B. Bouhou, S. Braccini, C. Bradaschia, P. R. Brady, V. B. Braginsky, M. Branchesi, J. E. Brau, J. Breyer, T. Briant, D. O. Bridges, A. Brillet, M. Brinkmann, V. Brisson, M. Britzger, A. F. Brooks, D. A. Brown, T. Bulik, H. J. Bulten, A. Buonanno, J. Burguet-Castell, D. Buskulic, C. Buy, R. L. Byer, L. Cadonati, G. Cagnoli, E. Calloni, J. B. Camp, P. Campsie, K. Cannon, B. Canuel, J. Cao, C. D. Capano, F. Carbognani, L. Carbone, S. Caride, S. Caudill, M. Cavaglia, F. Cavalier, R. Cavalieri, G. Cella, C. Cepeda, E. Cesarini, T. Chalermsongsak, P. Charlton, E. Chassande-Mottin, W. Chen, X. Chen, Y. Chen, A. Chincarini, A. Chiummo, H. S. Cho, J. Chow, N. Christensen, S. S. Y. Chua, C. T. Y. Chung, S. Chung, G. Ciani, F. Clara, D. E. Clark, J. A. Clark, J. H. Clayton, F. Cleva, E. Coccia, P.-F. Cohadon, C. N. Colacino, A. Colla, M. Colombini, A. Conte, R. Conte, D. Cook, T. R. Corbitt, M. Cordier, N. Cornish, A. Corsi, C. A. Costa, M. Coughlin, J.-P. Coulon, P. Couvares, D. M. Coward, M. Cowart, D. C. Coyne, J. D. E. Creighton, T. D. Creighton, A. M. Cruise, A. Cumming, L. Cunningham, E. Cuoco, R. M. Cutler, K. Dahl, M. Damjanic, S. L. Danilishin, S. D'Antonio, K. Danzmann, V. Dattilo, B. Daudert, H. Daveloza, M. Davier, E. J. Daw, R. Day, T. Dayanga, R. De Rosa, D. DeBra, G. Debreczeni, J. Degallaix, W. Del Pozzo, T. Dent, V. Dergachev, R. DeRosa, S. Dhurandhar, L. Di Fiore, A. Di Lieto, I. Di Palma, M. Di Paolo Emilio, A. Di Virgilio, M. Diaz, A. Dietz, F. Donovan, K. L. Dooley, S. Doravari, S. Dorsher, M. Drago, R. W. P. Drever, J. C. Driggers, Z. Du, J.-C. Dumas, S. Dwyer, T. Eberle, M. Edgar, M. Edwards, A. Effler, P. Ehrens, G. Endroczi, R. Engel, T. Etzel, K. Evans, M. Evans, T. Evans, M. Factourovich, V. Fafone, S. Fairhurst, B. F. Farr, M. Favata, D. Fazi, H. Fehrmann, D. Feldbaum, I. Ferrante, F. Ferrini, F. Fidecaro, L. S. Finn, I. Fiori, R. P. Fisher, R. Flaminio, S. Foley, E. Forsi, L. A. Forte, N. Fotopoulos, J.-D. Fournier, J. Franc, S. Franco, S. Frasca, F. Frasconi, M. Frede, M. A. Frei, Z. Frei, A. Freise, R. Frey, T. T. Fricke, D. Friedrich, P. Fritschel, V. V. Frolov, M.-K. Fujimoto, P. J. Fulda, M. Fyffe, J. Gair, M. Galimberti, L. Gammaitoni, J. Garcia, F. Garufi, M. E. Gaspar, G. Gelencser, G. Gemme, E. Genin, A. Gennai, L. A. Gergely, S. Ghosh, J. A. Giaime, S. Giampanis, K. D. Giardina, A. Giazotto, S. Gil-Casanova, C. Gill, J. Gleason, E. Goetz, G. Gonzalez, M. L. Gorodetsky, S. Gossler, R. Gouaty, C. Graef, P. B. Graff, M. Granata, A. Grant, C. Gray, R. J. S. Greenhalgh, A. M. Gretarsson, C. Griffo, H. Grote, K. Grover, S. Grunewald, G. M. Guidi, C. Guido, R. Gupta, E. K. Gustafson, R. Gustafson, J. M. Hallam, D. Hammer, G. Hammond, J. Hanks, C. Hanna, J. Hanson, J. Harms, G. M. Harry, I. W. Harry, E. D. Harstad, M. T. Hartman, K. Haughian, K. Hayama, J.-F. Hayau, J. Heefner, A. Heidmann, M. C. Heintze, H. Heitmann, P. Hello, G. Hemming, M. A. Hendry, I. S. Heng, A. W. Heptonstall, V. Herrera, M. Heurs, M. Hewitson, S. Hild, D. Hoak, K. A. Hodge, K. Holt, M. Holtrop, T. Hong, S. Hooper, J. Hough, E. J. Howell, B. Hughey, S. Husa, S. H. Huttner, T. Huynh-Dinh, D. R. Ingram, R. Inta, T. Isogai, A. Ivanov, K. Izumi, M. Jacobson, E. James, Y. J. Jang, P. Jaranowski, E. Jesse, W. W. Johnson, D. I. Jones, R. Jones, R.J.G. Jonker, L. Ju, P. Kalmus, V. Kalogera, S. Kandhasamy, G. Kang, J. B. Kanner, M. Kasprzack, R. Kasturi, E. Katsavounidis, W. Katzman, H. Kaufer, K. Kaufman, K. Kawabe, S. Kawamura, F. Kawazoe, D. Keitel, D. Kelley, W. Kells, D. G. Keppel, Z. Keresztes, A. Khalaidovski, F. Y. Khalili, E. A. Khazanov, B. K. Kim, C. Kim, H. Kim, K. Kim, N. Kim, Y. M. Kim, P. J. King, D. L. Kinzel, J. S. Kissel, S. Klimenko, J. Kline, K. Kokeyama, V. Kondrashov, S. Koranda, W. Z. Korth, I. Kowalska, D. Kozak, V. Kringel, B. Krishnan, A. Krolak, G. Kuehn, P. Kumar, R. Kumar, R. Kurdyumov, P. Kwee, P. K. Lam, M. Landry, A. Langley, B. Lantz, N. Lastzka, C. Lawrie, A. Lazzarini, A. Le Roux, P. Leaci, C. H. Lee, H. K. Lee, H. M. Lee, J. R. Leong, I. Leonor, N. Leroy, N. Letendre, V. Lhuillier, J. Li, T.G.F. Li, P. E. Lindquist, V. Litvine, Y. Liu, Z. Liu, N. A. Lockerbie, D. Lodhia, J. Logue, M. Lorenzini, V. Loriette, M. Lormand, G. Losurdo, J. Lough, M. Lubinski, H. Lueck, A. P. Lundgren, J. Macarthur, E. Macdonald, B. Machenschalk, M. MacInnis, D. M. Macleod, M. Mageswaran, K. Mailand, E. Majorana, I. Maksimovic, V. Malvezzi, N. Man, I. Mandel, V. Mandic, M. Mantovani, F. Marchesoni, F. Marion, S. Marka, Z. Marka, A. Markosyan, E. Maros, J. Marque, F. Martelli, I. W. Martin, R. M. Martin, J. N. Marx, K. Mason, A. Masserot, F. Matichard, L. Matone, R. A. Matzner, N. Mavalvala, G. Mazzolo, R. McCarthy, D. E. McClelland, S. C. McGuire, G. McIntyre, J. McIver, G. D. Meadors, M. Mehmet, T. Meier, A. Melatos, A. C. Melissinos, G. Mendell, D. F. Menendez, R. A. Mercer, S. Meshkov, C. Messenger, M. S. Meyer, H. Miao, C. Michel, L. Milano, J. Miller, Y. Minenkov, C. M. F. Mingarelli, V. P. Mitrofanov, G. Mitselmakher, R. Mittleman, B. Moe, M. Mohan, S. R. P. Mohapatra, D. Moraru, G. Moreno, N. Morgado, A. Morgia, T. Mori, S. R. Morriss, S. Mosca, K. Mossavi, B. Mours, C. M. Mow-Lowry, C. L. Mueller, G. Mueller, S. Mukherjee, A. Mullavey, H. Mueller-Ebhardt, J. Munch, D. Murphy, P. G. Murray, A. Mytidis, T. Nash, L. Naticchioni, V. Necula, J. Nelson, I. Neri, G. Newton, T. Nguyen, A. Nishizawa, A. Nitz, F. Nocera, D. Nolting, M. E. Normandin, L. Nuttall, E. Ochsner, J. O'Dell, E. Oelker, G. H. Ogin, J. J. Oh, S. H. Oh, R. G. Oldenberg, B. O'Reilly, R. O'Shaughnessy, C. Osthelder, C. D. Ott, D. J. Ottaway, R. S. Ottens, H. Overmier, B. J. Owen, A. Page, L. Palladino, C. Palomba, Y. Pan, C. Pankow, F. Paoletti, R. Paoletti, M. A. Papa, M. Parisi, A. Pasqualetti, R. Passaquieti, D. Passuello, M. Pedraza, S. Penn, A. Perreca, G. Persichetti, M. Phelps, M. Pichot, M. Pickenpack, F. Piergiovanni, V. Pierro, M. Pihlaja, L. Pinard, I. M. Pinto, M. Pitkin, H. J. Pletsch, M. V. Plissi, R. Poggiani, J. Poeld, F. Postiglione, C. Poux, M. Prato, V. Predoi, T. Prestegard, L. R. Price, M. Prijatelj, M. Principe, S. Privitera, R. Prix, G. A. Prodi, L. G. Prokhorov, O. Puncken, M. Punturo, P. Puppo, V. Quetschke, R. Quitzow-James, F. J. Raab, D. S. Rabeling, I. Racz, H. Radkins, P. Raffai, M. Rakhmanov, C. Ramet, B. Rankins, P. Rapagnani, V. Raymond, V. Re, C. M. Reed, T. Reed, T. Regimbau, S. Reid, D. H. Reitze, F. Ricci, R. Riesen, K. Riles, M. Roberts, N. A. Robertson, F. Robinet, C. Robinson, E. L. Robinson, A. Rocchi, S. Roddy, C. Rodriguez, M. Rodruck, L. Rolland, J. G. Rollins, R. Romano, J. H. Romie, D. Rosinska, C. Roever, S. Rowan, A. Ruediger, P. Ruggi, K. Ryan, F. Salemi, L. Sammut, V. Sandberg, S. Sankar, V. Sannibale, L. Santamaria, I. Santiago-Prieto, G. 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Yancey, H. Yang, D. Yeaton-Massey, S. Yoshida, M. Yvert, A. Zadrozny, M. Zanolin, J.-P. Zendri, F. Zhang, L. Zhang, C. Zhao, N. Zotov, M. E. Zucker, J. Zweizig
Search for Gravitational Waves from Binary Black Hole Inspiral, Merger and Ringdown in LIGO-Virgo Data from 2009-2010
15 pages PDFLaTeX, minor changes to correspond with published version. An archived version with data for plots and tables is at https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p1200024 . A Science Summary of the paper for education and public outreach is at http://www.ligo.org/science/Publication-S6CBCHM/index.php
Phys. Rev. D 87, 022002 (2013)
10.1103/PhysRevD.87.022002
LIGO-P1200024
gr-qc astro-ph.CO astro-ph.HE
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We report a search for gravitational waves from the inspiral, merger and ringdown of binary black holes (BBH) with total mass between 25 and 100 solar masses, in data taken at the LIGO and Virgo observatories between July 7, 2009 and October 20, 2010. The maximum sensitive distance of the detectors over this period for a (20,20) Msun coalescence was 300 Mpc. No gravitational wave signals were found. We thus report upper limits on the astrophysical coalescence rates of BBH as a function of the component masses for non-spinning components, and also evaluate the dependence of the search sensitivity on component spins aligned with the orbital angular momentum. We find an upper limit at 90% confidence on the coalescence rate of BBH with non-spinning components of mass between 19 and 28 Msun of 3.3 \times 10^-7 mergers /Mpc^3 /yr.
[ { "created": "Fri, 28 Sep 2012 14:26:12 GMT", "version": "v1" }, { "created": "Thu, 4 Oct 2012 19:45:02 GMT", "version": "v2" }, { "created": "Mon, 25 Feb 2013 11:11:33 GMT", "version": "v3" } ]
2013-02-26
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A.", "" ], [ "Lodhia", "D.", "" ], [ "Logue", "J.", "" ], [ "Lorenzini", "M.", "" ], [ "Loriette", "V.", "" ], [ "Lormand", "M.", "" ], [ "Losurdo", "G.", "" ], [ "Lough", "J.", "" ], [ "Lubinski", "M.", "" ], [ "Lueck", "H.", "" ], [ "Lundgren", "A. P.", "" ], [ "Macarthur", "J.", "" ], [ "Macdonald", "E.", "" ], [ "Machenschalk", "B.", "" ], [ "MacInnis", "M.", "" ], [ "Macleod", "D. M.", "" ], [ "Mageswaran", "M.", "" ], [ "Mailand", "K.", "" ], [ "Majorana", "E.", "" ], [ "Maksimovic", "I.", "" ], [ "Malvezzi", "V.", "" ], [ "Man", "N.", "" ], [ "Mandel", "I.", "" ], [ "Mandic", "V.", "" ], [ "Mantovani", "M.", "" ], [ "Marchesoni", "F.", "" ], [ "Marion", "F.", "" ], [ "Marka", "S.", "" ], [ "Marka", "Z.", "" ], [ "Markosyan", "A.", "" ], [ "Maros", "E.", "" ], [ "Marque", "J.", "" ], [ "Martelli", "F.", "" ], [ "Martin", "I. W.", "" ], [ "Martin", "R. M.", "" ], [ "Marx", "J. N.", "" ], [ "Mason", "K.", "" ], [ "Masserot", "A.", "" ], [ "Matichard", "F.", "" ], [ "Matone", "L.", "" ], [ "Matzner", "R. A.", "" ], [ "Mavalvala", "N.", "" ], [ "Mazzolo", "G.", "" ], [ "McCarthy", "R.", "" ], [ "McClelland", "D. E.", "" ], [ "McGuire", "S. C.", "" ], [ "McIntyre", "G.", "" ], [ "McIver", "J.", "" ], [ "Meadors", "G. D.", "" ], [ "Mehmet", "M.", "" ], [ "Meier", "T.", "" ], [ "Melatos", "A.", "" ], [ "Melissinos", "A. C.", "" ], [ "Mendell", "G.", "" ], [ "Menendez", "D. F.", "" ], [ "Mercer", "R. A.", "" ], [ "Meshkov", "S.", "" ], [ "Messenger", "C.", "" ], [ "Meyer", "M. S.", "" ], [ "Miao", "H.", "" ], [ "Michel", "C.", "" ], [ "Milano", "L.", "" ], [ "Miller", "J.", "" ], [ "Minenkov", "Y.", "" ], [ "Mingarelli", "C. M. F.", "" ], [ "Mitrofanov", "V. P.", "" ], [ "Mitselmakher", "G.", "" ], [ "Mittleman", "R.", "" ], [ "Moe", "B.", "" ], [ "Mohan", "M.", "" ], [ "Mohapatra", "S. R. P.", "" ], [ "Moraru", "D.", "" ], [ "Moreno", "G.", "" ], [ "Morgado", "N.", "" ], [ "Morgia", "A.", "" ], [ "Mori", "T.", "" ], [ "Morriss", "S. R.", "" ], [ "Mosca", "S.", "" ], [ "Mossavi", "K.", "" ], [ "Mours", "B.", "" ], [ "Mow-Lowry", "C. M.", "" ], [ "Mueller", "C. L.", "" ], [ "Mueller", "G.", "" ], [ "Mukherjee", "S.", "" ], [ "Mullavey", "A.", "" ], [ "Mueller-Ebhardt", "H.", "" ], [ "Munch", "J.", "" ], [ "Murphy", "D.", "" ], [ "Murray", "P. G.", "" ], [ "Mytidis", "A.", "" ], [ "Nash", "T.", "" ], [ "Naticchioni", "L.", "" ], [ "Necula", "V.", "" ], [ "Nelson", "J.", "" ], [ "Neri", "I.", "" ], [ "Newton", "G.", "" ], [ "Nguyen", "T.", "" ], [ "Nishizawa", "A.", "" ], [ "Nitz", "A.", "" ], [ "Nocera", "F.", "" ], [ "Nolting", "D.", "" ], [ "Normandin", "M. E.", "" ], [ "Nuttall", "L.", "" ], [ "Ochsner", "E.", "" ], [ "O'Dell", "J.", "" ], [ "Oelker", "E.", "" ], [ "Ogin", "G. H.", "" ], [ "Oh", "J. J.", "" ], [ "Oh", "S. H.", "" ], [ "Oldenberg", "R. G.", "" ], [ "O'Reilly", "B.", "" ], [ "O'Shaughnessy", "R.", "" ], [ "Osthelder", "C.", "" ], [ "Ott", "C. D.", "" ], [ "Ottaway", "D. J.", "" ], [ "Ottens", "R. S.", "" ], [ "Overmier", "H.", "" ], [ "Owen", "B. J.", "" ], [ "Page", "A.", "" ], [ "Palladino", "L.", "" ], [ "Palomba", "C.", "" ], [ "Pan", "Y.", "" ], [ "Pankow", "C.", "" ], [ "Paoletti", "F.", "" ], [ "Paoletti", "R.", "" ], [ "Papa", "M. A.", "" ], [ "Parisi", "M.", "" ], [ "Pasqualetti", "A.", "" ], [ "Passaquieti", "R.", "" ], [ "Passuello", "D.", "" ], [ "Pedraza", "M.", "" ], [ "Penn", "S.", "" ], [ "Perreca", "A.", "" ], [ "Persichetti", "G.", "" ], [ "Phelps", "M.", "" ], [ "Pichot", "M.", "" ], [ "Pickenpack", "M.", "" ], [ "Piergiovanni", "F.", "" ], [ "Pierro", "V.", "" ], [ "Pihlaja", "M.", "" ], [ "Pinard", "L.", "" ], [ "Pinto", "I. M.", "" ], [ "Pitkin", "M.", "" ], [ "Pletsch", "H. J.", "" ], [ "Plissi", "M. V.", "" ], [ "Poggiani", "R.", "" ], [ "Poeld", "J.", "" ], [ "Postiglione", "F.", "" ], [ "Poux", "C.", "" ], [ "Prato", "M.", "" ], [ "Predoi", "V.", "" ], [ "Prestegard", "T.", "" ], [ "Price", "L. R.", "" ], [ "Prijatelj", "M.", "" ], [ "Principe", "M.", "" ], [ "Privitera", "S.", "" ], [ "Prix", "R.", "" ], [ "Prodi", "G. A.", "" ], [ "Prokhorov", "L. G.", "" ], [ "Puncken", "O.", "" ], [ "Punturo", "M.", "" ], [ "Puppo", "P.", "" ], [ "Quetschke", "V.", "" ], [ "Quitzow-James", "R.", "" ], [ "Raab", "F. J.", "" ], [ "Rabeling", "D. S.", "" ], [ "Racz", "I.", "" ], [ "Radkins", "H.", "" ], [ "Raffai", "P.", "" ], [ "Rakhmanov", "M.", "" ], [ "Ramet", "C.", "" ], [ "Rankins", "B.", "" ], [ "Rapagnani", "P.", "" ], [ "Raymond", "V.", "" ], [ "Re", "V.", "" ], [ "Reed", "C. M.", "" ], [ "Reed", "T.", "" ], [ "Regimbau", "T.", "" ], [ "Reid", "S.", "" ], [ "Reitze", "D. H.", "" ], [ "Ricci", "F.", "" ], [ "Riesen", "R.", "" ], [ "Riles", "K.", "" ], [ "Roberts", "M.", "" ], [ "Robertson", "N. A.", "" ], [ "Robinet", "F.", "" ], [ "Robinson", "C.", "" ], [ "Robinson", "E. L.", "" ], [ "Rocchi", "A.", "" ], [ "Roddy", "S.", "" ], [ "Rodriguez", "C.", "" ], [ "Rodruck", "M.", "" ], [ "Rolland", "L.", "" ], [ "Rollins", "J. G.", "" ], [ "Romano", "R.", "" ], [ "Romie", "J. H.", "" ], [ "Rosinska", "D.", "" ], [ "Roever", "C.", "" ], [ "Rowan", "S.", "" ], [ "Ruediger", "A.", "" ], [ "Ruggi", "P.", "" ], [ "Ryan", "K.", "" ], [ "Salemi", "F.", "" ], [ "Sammut", "L.", "" ], [ "Sandberg", "V.", "" ], [ "Sankar", "S.", "" ], [ "Sannibale", "V.", "" ], [ "Santamaria", "L.", "" ], [ "Santiago-Prieto", "I.", "" ], [ "Santostasi", "G.", "" ], [ "Saracco", "E.", "" ], [ "Sassolas", "B.", "" ], [ "Sathyaprakash", "B. S.", "" ], [ "Saulson", "P. R.", "" ], [ "Savage", "R. L.", "" ], [ "Schilling", "R.", "" ], [ "Schnabel", "R.", "" ], [ "Schofield", "R. M. S.", "" ], [ "Schulz", "B.", "" ], [ "Schutz", "B. F.", "" ], [ "Schwinberg", "P.", "" ], [ "Scott", "J.", "" ], [ "Scott", "S. M.", "" ], [ "Seifert", "F.", "" ], [ "Sellers", "D.", "" ], [ "Sentenac", "D.", "" ], [ "Sergeev", "A.", "" ], [ "Shaddock", "D. A.", "" ], [ "Shaltev", "M.", "" ], [ "Shapiro", "B.", "" ], [ "Shawhan", "P.", "" ], [ "Shoemaker", "D. H.", "" ], [ "Sidery", "T. L", "" ], [ "Siemens", "X.", "" ], [ "Sigg", "D.", "" ], [ "Simakov", "D.", "" ], [ "Singer", "A.", "" ], [ "Singer", "L.", "" ], [ "Sintes", "A. M.", "" ], [ "Skelton", "G. R.", "" ], [ "Slagmolen", "B. J. J.", "" ], [ "Slutsky", "J.", "" ], [ "Smith", "J. R.", "" ], [ "Smith", "M. R.", "" ], [ "Smith", "R. J. E.", "" ], [ "Smith-Lefebvre", "N. D.", "" ], [ "Somiya", "K.", "" ], [ "Sorazu", "B.", "" ], [ "Speirits", "F. C.", "" ], [ "Sperandio", "L.", "" ], [ "Stefszky", "M.", "" ], [ "Steinert", "E.", "" ], [ "Steinlechner", "J.", "" ], [ "Steinlechner", "S.", "" ], [ "Steplewski", "S.", "" ], [ "Stochino", "A.", "" ], [ "Stone", "R.", "" ], [ "Strain", "K. A.", "" ], [ "Strigin", "S. E.", "" ], [ "Stroeer", "A. S.", "" ], [ "Sturani", "R.", "" ], [ "Stuver", "A. L.", "" ], [ "Summerscales", "T. Z.", "" ], [ "Sung", "M.", "" ], [ "Susmithan", "S.", "" ], [ "Sutton", "P. J.", "" ], [ "Swinkels", "B.", "" ], [ "Szeifert", "G.", "" ], [ "Tacca", "M.", "" ], [ "Taffarello", "L.", "" ], [ "Talukder", "D.", "" ], [ "Tanner", "D. B.", "" ], [ "Tarabrin", "S. P.", "" ], [ "Taylor", "R.", "" ], [ "ter Braack", "A. P. M.", "" ], [ "Thomas", "P.", "" ], [ "Thorne", "K. A.", "" ], [ "Thorne", "K. S.", "" ], [ "Thrane", "E.", "" ], [ "Thuering", "A.", "" ], [ "Titsler", "C.", "" ], [ "Tokmakov", "K. V.", "" ], [ "Tomlinson", "C.", "" ], [ "Toncelli", "A.", "" ], [ "Tonelli", "M.", "" ], [ "Torre", "O.", "" ], [ "Torres", "C. V.", "" ], [ "Torrie", "C. I.", "" ], [ "Tournefier", "E.", "" ], [ "Travasso", "F.", "" ], [ "Traylor", "G.", "" ], [ "Tse", "M.", "" ], [ "Ugolini", "D.", "" ], [ "Vahlbruch", "H.", "" ], [ "Vajente", "G.", "" ], [ "Brand", "J. F. J. van den", "" ], [ "Broeck", "C. Van Den", "" ], [ "van der Putten", "S.", "" ], [ "van Veggel", "A. A.", "" ], [ "Vass", "S.", "" ], [ "Vasuth", "M.", "" ], [ "Vaulin", "R.", "" ], [ "Vavoulidis", "M.", "" ], [ "Vecchio", "A.", "" ], [ "Vedovato", "G.", "" ], [ "Veitch", "J.", "" ], [ "Veitch", "P. J.", "" ], [ "Venkateswara", "K.", "" ], [ "Verkindt", "D.", "" ], [ "Vetrano", "F.", "" ], [ "Vicere", "A.", "" ], [ "Villar", "A. E.", "" ], [ "Vinet", "J. -Y.", "" ], [ "Vitale", "S.", "" ], [ "Vocca", "H.", "" ], [ "Vorvick", "C.", "" ], [ "Vyatchanin", "S. P.", "" ], [ "Wade", "A.", "" ], [ "Wade", "L.", "" ], [ "Wade", "M.", "" ], [ "Waldman", "S. J.", "" ], [ "Wallace", "L.", "" ], [ "Wan", "Y.", "" ], [ "Wang", "M.", "" ], [ "Wang", "X.", "" ], [ "Wanner", "A.", "" ], [ "Ward", "R. L.", "" ], [ "Was", "M.", "" ], [ "Weinert", "M.", "" ], [ "Weinstein", "A. J.", "" ], [ "Weiss", "R.", "" ], [ "Welborn", "T.", "" ], [ "Wen", "L.", "" ], [ "Wessels", "P.", "" ], [ "West", "M.", "" ], [ "Westphal", "T.", "" ], [ "Wette", "K.", "" ], [ "Whelan", "J. T.", "" ], [ "Whitcomb", "S. E.", "" ], [ "White", "D. J.", "" ], [ "Whiting", "B. F.", "" ], [ "Wiesner", "K.", "" ], [ "Wilkinson", "C.", "" ], [ "Willems", "P. A.", "" ], [ "Williams", "L.", "" ], [ "Williams", "R.", "" ], [ "Willke", "B.", "" ], [ "Wimmer", "M.", "" ], [ "Winkelmann", "L.", "" ], [ "Winkler", "W.", "" ], [ "Wipf", "C. C.", "" ], [ "Wiseman", "A. G.", "" ], [ "Wittel", "H.", "" ], [ "Woan", "G.", "" ], [ "Wooley", "R.", "" ], [ "Worden", "J.", "" ], [ "Yablon", "J.", "" ], [ "Yakushin", "I.", "" ], [ "Yamamoto", "H.", "" ], [ "Yamamoto", "K.", "" ], [ "Yancey", "C. C.", "" ], [ "Yang", "H.", "" ], [ "Yeaton-Massey", "D.", "" ], [ "Yoshida", "S.", "" ], [ "Yvert", "M.", "" ], [ "Zadrozny", "A.", "" ], [ "Zanolin", "M.", "" ], [ "Zendri", "J. -P.", "" ], [ "Zhang", "F.", "" ], [ "Zhang", "L.", "" ], [ "Zhao", "C.", "" ], [ "Zotov", "N.", "" ], [ "Zucker", "M. E.", "" ], [ "Zweizig", "J.", "" ] ]
We report a search for gravitational waves from the inspiral, merger and ringdown of binary black holes (BBH) with total mass between 25 and 100 solar masses, in data taken at the LIGO and Virgo observatories between July 7, 2009 and October 20, 2010. The maximum sensitive distance of the detectors over this period for a (20,20) Msun coalescence was 300 Mpc. No gravitational wave signals were found. We thus report upper limits on the astrophysical coalescence rates of BBH as a function of the component masses for non-spinning components, and also evaluate the dependence of the search sensitivity on component spins aligned with the orbital angular momentum. We find an upper limit at 90% confidence on the coalescence rate of BBH with non-spinning components of mass between 19 and 28 Msun of 3.3 \times 10^-7 mergers /Mpc^3 /yr.
2005.08313
Francesco Bajardi
Francesco Bajardi and Salvatore Capozziello
f(G) Noether cosmology
null
European Physic Journal C 80 (2020) no.8, 704
10.1140/epjc/s10052-020-8258-2
null
gr-qc astro-ph.CO hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We develop the $n$-dimensional cosmology for $f(\mathcal{G})$ gravity, where $\mathcal{G}$ is the \emph{Gauss-Bonnet} topological invariant. Specifically, by the so-called Noether Symmetry Approach, we select $f(\mathcal{G})\simeq \mathcal{G}^k$ power-law models where $k$ is a real number. In particular, the case $k = 1/2$ for $n=4$ results equivalent to General Relativity showing that we do not need to impose the action $R+f(\mathcal{G})$ to reproduce the Einstein theory. As a further result, de Sitter solutions are recovered in the case where $f(\mathcal{G})$ is non-minimally coupled to a scalar field. This means that issues like inflation and dark energy can be addressed in this framework. Finally, we develop the Hamiltonian formalism for the related minisuperspace and discuss the quantum cosmology for this model.
[ { "created": "Sun, 17 May 2020 17:26:17 GMT", "version": "v1" }, { "created": "Thu, 16 Jul 2020 19:38:31 GMT", "version": "v2" } ]
2021-11-29
[ [ "Bajardi", "Francesco", "" ], [ "Capozziello", "Salvatore", "" ] ]
We develop the $n$-dimensional cosmology for $f(\mathcal{G})$ gravity, where $\mathcal{G}$ is the \emph{Gauss-Bonnet} topological invariant. Specifically, by the so-called Noether Symmetry Approach, we select $f(\mathcal{G})\simeq \mathcal{G}^k$ power-law models where $k$ is a real number. In particular, the case $k = 1/2$ for $n=4$ results equivalent to General Relativity showing that we do not need to impose the action $R+f(\mathcal{G})$ to reproduce the Einstein theory. As a further result, de Sitter solutions are recovered in the case where $f(\mathcal{G})$ is non-minimally coupled to a scalar field. This means that issues like inflation and dark energy can be addressed in this framework. Finally, we develop the Hamiltonian formalism for the related minisuperspace and discuss the quantum cosmology for this model.
1205.7088
Tomohiro Harada
Tomohiro Harada, Hiroya Nemoto, Umpei Miyamoto
Upper limits of particle emission from high-energy collision and reaction near a maximally rotating Kerr black hole
22 pages, 3 figures, typos corrected, reference updated, accepted for publication in Physical Review D, typos corrected
Phys.Rev.D86:024027,2012
10.1103/PhysRevD.86.024027
RUP-12-4
gr-qc astro-ph.HE hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The center-of-mass energy of two particles colliding near the horizon of a maximally rotating black hole can be arbitrarily high if the angular momentum of either of the incident particles is fine-tuned, which we call a critical particle. We study particle emission from such high-energy collision and reaction in the equatorial plane fully analytically. We show that the unconditional upper limit of the energy of the emitted particle is given by 218.6% of that of the injected critical particle, irrespective of the details of the reaction and this upper limit can be realized for massless particle emission. The upper limit of the energy extraction efficiency for this emission as a collisional Penrose process is given by 146.6%, which can be realized in the collision of two massive particles with optimized mass ratio. Moreover, we analyze perfectly elastic collision, Compton scattering, and pair annihilation and show that net positive energy extraction is really possible for these three reactions. The Compton scattering is most efficient among them and the efficiency can reach 137.2%. On the other hand, our result is qualitatively consistent with the earlier claim that the mass and energy of the emitted particle are at most of order the total energy of the injected particles and hence we can observe neither super-heavy nor super-energetic particles.
[ { "created": "Thu, 31 May 2012 19:46:12 GMT", "version": "v1" }, { "created": "Sat, 2 Jun 2012 17:07:36 GMT", "version": "v2" }, { "created": "Sat, 14 Jul 2012 01:52:09 GMT", "version": "v3" }, { "created": "Fri, 7 Sep 2012 12:58:06 GMT", "version": "v4" } ]
2015-06-05
[ [ "Harada", "Tomohiro", "" ], [ "Nemoto", "Hiroya", "" ], [ "Miyamoto", "Umpei", "" ] ]
The center-of-mass energy of two particles colliding near the horizon of a maximally rotating black hole can be arbitrarily high if the angular momentum of either of the incident particles is fine-tuned, which we call a critical particle. We study particle emission from such high-energy collision and reaction in the equatorial plane fully analytically. We show that the unconditional upper limit of the energy of the emitted particle is given by 218.6% of that of the injected critical particle, irrespective of the details of the reaction and this upper limit can be realized for massless particle emission. The upper limit of the energy extraction efficiency for this emission as a collisional Penrose process is given by 146.6%, which can be realized in the collision of two massive particles with optimized mass ratio. Moreover, we analyze perfectly elastic collision, Compton scattering, and pair annihilation and show that net positive energy extraction is really possible for these three reactions. The Compton scattering is most efficient among them and the efficiency can reach 137.2%. On the other hand, our result is qualitatively consistent with the earlier claim that the mass and energy of the emitted particle are at most of order the total energy of the injected particles and hence we can observe neither super-heavy nor super-energetic particles.
gr-qc/9305014
H. Shinkai
Hisa-aki SHINKAI and Kei-ichi MAEDA
Can Gravitational Waves Prevent Inflation?
LaTeX, 11 pages, 3 figures are available on request <To 62L508@jpnwas00.bitnet (Hisa-aki SHINKAI)>, WU-AP/29/93
Phys.Rev.D48:3910-3913,1993
10.1103/PhysRevD.48.3910
null
gr-qc
null
To investigate the cosmic no hair conjecture, we analyze numerically 1-dimensional plane symmetrical inhomogeneities due to gravitational waves in vacuum spacetimes with a positive cosmological constant. Assuming periodic gravitational pulse waves initially, we study the time evolution of those waves and the nature of their collisions. As measures of inhomogeneity on each hypersurface, we use the 3-dimensional Riemann invariant ${\cal I}\equiv {}~^{(3)\!}R_{ijkl}~^{(3)\!}R^{ijkl}$ and the electric and magnetic parts of the Weyl tensor. We find a temporal growth of the curvature in the waves' collision region, but the overall expansion of the universe later overcomes this effect. No singularity appears and the result is a ``no hair" de Sitter spacetime. The waves we study have amplitudes between $0.020\Lambda \leq {\cal I}^{1/2} \leq 125.0\Lambda$ and widths between $0.080l_H \leq l \leq 2.5l_H$, where $l_H=(\Lambda/3)^{-1/2}$, the horizon scale of de Sitter spacetime. This supports the cosmic no hair conjecture.
[ { "created": "Tue, 18 May 1993 12:29:58 GMT", "version": "v1" } ]
2010-11-01
[ [ "SHINKAI", "Hisa-aki", "" ], [ "MAEDA", "Kei-ichi", "" ] ]
To investigate the cosmic no hair conjecture, we analyze numerically 1-dimensional plane symmetrical inhomogeneities due to gravitational waves in vacuum spacetimes with a positive cosmological constant. Assuming periodic gravitational pulse waves initially, we study the time evolution of those waves and the nature of their collisions. As measures of inhomogeneity on each hypersurface, we use the 3-dimensional Riemann invariant ${\cal I}\equiv {}~^{(3)\!}R_{ijkl}~^{(3)\!}R^{ijkl}$ and the electric and magnetic parts of the Weyl tensor. We find a temporal growth of the curvature in the waves' collision region, but the overall expansion of the universe later overcomes this effect. No singularity appears and the result is a ``no hair" de Sitter spacetime. The waves we study have amplitudes between $0.020\Lambda \leq {\cal I}^{1/2} \leq 125.0\Lambda$ and widths between $0.080l_H \leq l \leq 2.5l_H$, where $l_H=(\Lambda/3)^{-1/2}$, the horizon scale of de Sitter spacetime. This supports the cosmic no hair conjecture.
2305.10715
Cosimo Bambi
Cosimo Bambi
X-Ray Tests of General Relativity with Black Holes
16 pages, 5 figures. Invited contribution for the Special Issue "Role of Black Holes in Testing Modified Theories of Gravity" for Symmetry (Ed. Rahul Kumar Walia). v2: refereed version
Symmetry 15: 1277 (2023)
10.3390/sym15061277
null
gr-qc astro-ph.HE
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
General relativity is one of the pillars of modern physics. For decades, the theory has been mainly tested in the weak field regime with experiments in the Solar System and radio observations of binary pulsars. Until 2015, the strong field regime was almost completely unexplored. Thanks to new observational facilities, the situation has dramatically changed in the last few years. Today we have gravitational wave data of the coalesce of stellar-mass compact objects from the LIGO-Virgo-KAGRA Collaboration, images at mm wavelengths of the supermassive black holes in M87$^*$ and SgrA$^*$ from the Event Horizon Telescope Collaboration, and X-ray data of accreting compact objects from a number of X-ray missions. Gravitational wave tests and black hole imaging tests are certainly more popular and are discussed in other articles of this Special Issue. The aim of the present manuscript is to provide a pedagogical review on X-ray tests of general relativity with black holes and to compare this kind of tests with those possible with gravitational wave data and black hole imaging.
[ { "created": "Thu, 18 May 2023 05:26:30 GMT", "version": "v1" }, { "created": "Sun, 18 Jun 2023 08:54:15 GMT", "version": "v2" } ]
2023-06-21
[ [ "Bambi", "Cosimo", "" ] ]
General relativity is one of the pillars of modern physics. For decades, the theory has been mainly tested in the weak field regime with experiments in the Solar System and radio observations of binary pulsars. Until 2015, the strong field regime was almost completely unexplored. Thanks to new observational facilities, the situation has dramatically changed in the last few years. Today we have gravitational wave data of the coalesce of stellar-mass compact objects from the LIGO-Virgo-KAGRA Collaboration, images at mm wavelengths of the supermassive black holes in M87$^*$ and SgrA$^*$ from the Event Horizon Telescope Collaboration, and X-ray data of accreting compact objects from a number of X-ray missions. Gravitational wave tests and black hole imaging tests are certainly more popular and are discussed in other articles of this Special Issue. The aim of the present manuscript is to provide a pedagogical review on X-ray tests of general relativity with black holes and to compare this kind of tests with those possible with gravitational wave data and black hole imaging.
1703.08503
Jonathan Richardson
Aaron Chou, Henry Glass, H. Richard Gustafson, Craig J. Hogan, Brittany L. Kamai, Ohkyung Kwon, Robert Lanza, Lee McCuller, Stephan S. Meyer, Jonathan W. Richardson, Chris Stoughton, Ray Tomlin, and Rainer Weiss
Interferometric Constraints on Quantum Geometrical Shear Noise Correlations
Matches the journal accepted version
Class. Quantum Grav. 34 165005 (2017)
10.1088/1361-6382/aa7bd3
FERMILAB-PUB-16-527
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Final measurements and analysis are reported from the first-generation Holometer, the first instrument capable of measuring correlated variations in space-time position at strain noise power spectral densities smaller than a Planck time. The apparatus consists of two co-located, but independent and isolated, 40 m power-recycled Michelson interferometers, whose outputs are cross-correlated to 25 MHz. The data are sensitive to correlations of differential position across the apparatus over a broad band of frequencies up to and exceeding the inverse light crossing time, 7.6 MHz. By measuring with Planck precision the correlation of position variations at spacelike separations, the Holometer searches for faint, irreducible correlated position noise backgrounds predicted by some models of quantum space-time geometry. The first-generation optical layout is sensitive to quantum geometrical noise correlations with shear symmetry---those that can be interpreted as a fundamental noncommutativity of space-time position in orthogonal directions. General experimental constraints are placed on parameters of a set of models of spatial shear noise correlations, with a sensitivity that exceeds the Planck-scale holographic information bound on position states by a large factor. This result significantly extends the upper limits placed on models of directional noncommutativity by currently operating gravitational wave observatories.
[ { "created": "Fri, 24 Mar 2017 16:54:26 GMT", "version": "v1" }, { "created": "Sun, 13 Aug 2017 20:41:56 GMT", "version": "v2" } ]
2017-08-15
[ [ "Chou", "Aaron", "" ], [ "Glass", "Henry", "" ], [ "Gustafson", "H. Richard", "" ], [ "Hogan", "Craig J.", "" ], [ "Kamai", "Brittany L.", "" ], [ "Kwon", "Ohkyung", "" ], [ "Lanza", "Robert", "" ], [ "McCuller", "Lee", "" ], [ "Meyer", "Stephan S.", "" ], [ "Richardson", "Jonathan W.", "" ], [ "Stoughton", "Chris", "" ], [ "Tomlin", "Ray", "" ], [ "Weiss", "Rainer", "" ] ]
Final measurements and analysis are reported from the first-generation Holometer, the first instrument capable of measuring correlated variations in space-time position at strain noise power spectral densities smaller than a Planck time. The apparatus consists of two co-located, but independent and isolated, 40 m power-recycled Michelson interferometers, whose outputs are cross-correlated to 25 MHz. The data are sensitive to correlations of differential position across the apparatus over a broad band of frequencies up to and exceeding the inverse light crossing time, 7.6 MHz. By measuring with Planck precision the correlation of position variations at spacelike separations, the Holometer searches for faint, irreducible correlated position noise backgrounds predicted by some models of quantum space-time geometry. The first-generation optical layout is sensitive to quantum geometrical noise correlations with shear symmetry---those that can be interpreted as a fundamental noncommutativity of space-time position in orthogonal directions. General experimental constraints are placed on parameters of a set of models of spatial shear noise correlations, with a sensitivity that exceeds the Planck-scale holographic information bound on position states by a large factor. This result significantly extends the upper limits placed on models of directional noncommutativity by currently operating gravitational wave observatories.
2005.03413
Reinoud Slagter
Reinoud Jan Slagter
On the dynamical 4D BTZ black hole solution in conformally invariant gravity
Version V4; some minor correction. 3 more figures added. Comment very welcome! 26 figures. 16 pages
null
10.4236/jmp.2020.1110105
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We review the (2+1)-dimensional Ba\u{n}ados-Teitelboim-Zanelli black hole solution in conformally invariant gravity, uplifted to (3+1)-dimensional spacetime. As matter content we use a scalar-gauge field. The metric is written as $g_{\mu\nu}=\omega^2\tilde g_{\mu\nu}$, where the {\it dilaton field} $\omega$ contains all the scale dependencies and where $\tilde g_{\mu\nu}$ represents the "un-physical" spacetime. A numerical solution is presented and shows how the dilaton can be treated on equal footing with the scalar field. The location of the apparent horizon and ergo-surface depends critically on the parameters and initial values of the model. It is not a hard task to find suitable initial parameters in order to obtain a regular and {\it singular free} $g_{\mu\nu}$ out of a BTZ-type solution for $\tilde g_{\mu\nu}$. In the vacuum situation, an {\it exact} time-dependent solution in the Eddington-Finkelstein coordinates is found, which is valid for the (2+1)-dimensional BTZ spacetime as well as for the uplifted (3+1)-dimensional BTZ spacetime. While $\tilde g_{\mu\nu}$ resembles the standard BTZ solution with its horizons, $g_{\mu\nu}$ is {\it flat}. The dilaton field becomes an infinitesimal renormalizable quantum field, which switches on and off Hawking radiation. This solution can be used to investigate the small distance scale of the model and the black hole complementarity issues. It can also be used to describe the problem how to map the quantum states of the outgoing radiation as seen by a distant observer and the ingoing by a local observer in a one-to-one way. The two observers will use a different conformal gauge. A possible connection is made with the antipodal identification and unitarity issues.
[ { "created": "Thu, 7 May 2020 12:25:40 GMT", "version": "v1" }, { "created": "Wed, 13 May 2020 21:29:15 GMT", "version": "v2" }, { "created": "Tue, 26 May 2020 20:30:53 GMT", "version": "v3" }, { "created": "Wed, 17 Jun 2020 19:09:25 GMT", "version": "v4" } ]
2020-12-02
[ [ "Slagter", "Reinoud Jan", "" ] ]
We review the (2+1)-dimensional Ba\u{n}ados-Teitelboim-Zanelli black hole solution in conformally invariant gravity, uplifted to (3+1)-dimensional spacetime. As matter content we use a scalar-gauge field. The metric is written as $g_{\mu\nu}=\omega^2\tilde g_{\mu\nu}$, where the {\it dilaton field} $\omega$ contains all the scale dependencies and where $\tilde g_{\mu\nu}$ represents the "un-physical" spacetime. A numerical solution is presented and shows how the dilaton can be treated on equal footing with the scalar field. The location of the apparent horizon and ergo-surface depends critically on the parameters and initial values of the model. It is not a hard task to find suitable initial parameters in order to obtain a regular and {\it singular free} $g_{\mu\nu}$ out of a BTZ-type solution for $\tilde g_{\mu\nu}$. In the vacuum situation, an {\it exact} time-dependent solution in the Eddington-Finkelstein coordinates is found, which is valid for the (2+1)-dimensional BTZ spacetime as well as for the uplifted (3+1)-dimensional BTZ spacetime. While $\tilde g_{\mu\nu}$ resembles the standard BTZ solution with its horizons, $g_{\mu\nu}$ is {\it flat}. The dilaton field becomes an infinitesimal renormalizable quantum field, which switches on and off Hawking radiation. This solution can be used to investigate the small distance scale of the model and the black hole complementarity issues. It can also be used to describe the problem how to map the quantum states of the outgoing radiation as seen by a distant observer and the ingoing by a local observer in a one-to-one way. The two observers will use a different conformal gauge. A possible connection is made with the antipodal identification and unitarity issues.
1604.06537
Sujoy Modak
Daniel Bedingham, Sujoy K. Modak and Daniel Sudarsky
Relativistic collapse dynamics and black hole information loss
39 pages, 3 figures
Phys. Rev. D 94, 045009 (2016)
10.1103/PhysRevD.94.045009
KEK-TH-1897
gr-qc hep-th quant-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study a proposal for the resolution of the black hole information puzzle within the context of modified versions of quantum theory involving spontaneous reduction of the quantum state. The theories of this kind, which were developed in order to address the so called "measurement problem" in quantum theory have, in the past, been framed in a non-relativistic setting and in that form they were previously applied to the black hole information problem. Here, and for the first time, we show in a simple toy model, a treatment of the problem within a fully relativistic setting. We also discuss the issues that the present analysis leaves as open problems to be dealt with in future refinements of the present approach.
[ { "created": "Fri, 22 Apr 2016 05:12:23 GMT", "version": "v1" } ]
2016-08-17
[ [ "Bedingham", "Daniel", "" ], [ "Modak", "Sujoy K.", "" ], [ "Sudarsky", "Daniel", "" ] ]
We study a proposal for the resolution of the black hole information puzzle within the context of modified versions of quantum theory involving spontaneous reduction of the quantum state. The theories of this kind, which were developed in order to address the so called "measurement problem" in quantum theory have, in the past, been framed in a non-relativistic setting and in that form they were previously applied to the black hole information problem. Here, and for the first time, we show in a simple toy model, a treatment of the problem within a fully relativistic setting. We also discuss the issues that the present analysis leaves as open problems to be dealt with in future refinements of the present approach.
gr-qc/9506018
Takashi Torii
Takashi Torii, Kei-ichi Maeda and Takashi Tachizawa
Cosmic Colored Black Holes
12 pages, latex, 4 figures (available upon request)
Phys.Rev.D52:4272-4276,1995
10.1103/PhysRevD.52.R4272
WU-AP/44/95
gr-qc
null
We present spherically symmetric static solutions (a particle-like solution and a black hole solution) in the Einstein-Yang-Mills system with a cosmological constant.Although their gravitational structures are locally similar to those of the Bartnik-McKinnon particles or the colored black holes, the asymptotic behavior becomes quite different because of the existence of a cosmological horizon. We also discuss their stability by means of a catastrophe theory as well as a linear perturbation analysis and find the number of unstable modes.
[ { "created": "Thu, 8 Jun 1995 01:44:23 GMT", "version": "v1" } ]
2010-01-08
[ [ "Torii", "Takashi", "" ], [ "Maeda", "Kei-ichi", "" ], [ "Tachizawa", "Takashi", "" ] ]
We present spherically symmetric static solutions (a particle-like solution and a black hole solution) in the Einstein-Yang-Mills system with a cosmological constant.Although their gravitational structures are locally similar to those of the Bartnik-McKinnon particles or the colored black holes, the asymptotic behavior becomes quite different because of the existence of a cosmological horizon. We also discuss their stability by means of a catastrophe theory as well as a linear perturbation analysis and find the number of unstable modes.
2211.03544
Amit Das
N. Rahman, M. Kalam, A. Das, S. Islam, F. Rahaman, M. Murshid
Thin-shell wormhole under non-commutative geometry inspired Einstein-Gauss-Bonnet gravity
17 pages, 11 figures
null
null
null
gr-qc
http://creativecommons.org/licenses/by/4.0/
Einstein-Gauss-Bonnet gravity is a generalization of the general relativity to higher dimensions in which the first and second-order terms correspond to general relativity and Einstein-Gauss-Bonnet gravity respectively. We construct a new class of five-dimensional (5D) thin-shell wormholes by the `Cut-Paste' technique from black holes in Einstein-Gauss-Bonnet gravity inspired by non-commutative geometry starting with a static spherically symmetric, Gaussian mass distribution as a source and for this structural form of the thin shell wormhole we have explored several salient features of the solution, viz., pressure-density profile, equation of state, the nature of wormhole, total amount of exotic matter content at the shell. We have also analyzed the linearized stability of the constructed wormhole. From our study we can assert that our model is found to be plausible with reference to the other model of thin-shell wormhole available in literature.
[ { "created": "Fri, 4 Nov 2022 04:22:37 GMT", "version": "v1" } ]
2022-11-08
[ [ "Rahman", "N.", "" ], [ "Kalam", "M.", "" ], [ "Das", "A.", "" ], [ "Islam", "S.", "" ], [ "Rahaman", "F.", "" ], [ "Murshid", "M.", "" ] ]
Einstein-Gauss-Bonnet gravity is a generalization of the general relativity to higher dimensions in which the first and second-order terms correspond to general relativity and Einstein-Gauss-Bonnet gravity respectively. We construct a new class of five-dimensional (5D) thin-shell wormholes by the `Cut-Paste' technique from black holes in Einstein-Gauss-Bonnet gravity inspired by non-commutative geometry starting with a static spherically symmetric, Gaussian mass distribution as a source and for this structural form of the thin shell wormhole we have explored several salient features of the solution, viz., pressure-density profile, equation of state, the nature of wormhole, total amount of exotic matter content at the shell. We have also analyzed the linearized stability of the constructed wormhole. From our study we can assert that our model is found to be plausible with reference to the other model of thin-shell wormhole available in literature.
gr-qc/0202035
Piotr Jaranowski
Piotr Jaranowski and Gerhard Sch\"afer
Lapse function for maximally sliced Brill-Lindquist initial data
REVTeX, 4 pages, accepted for publication in Phys. Rev. D (ver. 2: some more details added)
Phys.Rev.D65:127501,2002
10.1103/PhysRevD.65.127501
null
gr-qc
null
For binary black holes the lapse function corresponding to the Brill-Lindquist initial value solution for uncharged black holes is given in analytic form under the maximal slicing condition. In the limiting case of very small ratio of mass to separation between the black holes the surface defined by the zero value of the lapse function coincides with the minimal surfaces around the singularities.
[ { "created": "Mon, 11 Feb 2002 14:23:57 GMT", "version": "v1" }, { "created": "Thu, 11 Apr 2002 11:21:57 GMT", "version": "v2" } ]
2008-11-26
[ [ "Jaranowski", "Piotr", "" ], [ "Schäfer", "Gerhard", "" ] ]
For binary black holes the lapse function corresponding to the Brill-Lindquist initial value solution for uncharged black holes is given in analytic form under the maximal slicing condition. In the limiting case of very small ratio of mass to separation between the black holes the surface defined by the zero value of the lapse function coincides with the minimal surfaces around the singularities.
1903.01840
Claes Uggla
Claes Uggla and John Wainwright
Second order cosmological perturbations: new conserved quantities and the general solution at super-horizon scale
24 pages
Phys. Rev. D 100, 023544 (2019)
10.1103/PhysRevD.100.023544
null
gr-qc astro-ph.CO
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The study of long wavelength scalar perturbations, in particular the existence of conserved quantities when the perturbations are adiabatic, plays an important role in e.g. inflationary cosmology. In this paper we present some new conserved quantities at second order and relate them to the curvature perturbation in the uniform density gauge, $\zeta$, and the comoving curvature perturbation, ${\cal R}$. We also, for the first time, derive the general solution of the perturbed Einstein equations at second order, which thereby contains both growing and decaying modes, for adiabatic long wavelength perturbations for a stress-energy tensor with zero anisotropic stresses and zero heat flux. The derivation uses the total matter gauge, but results are subsequently translated to the uniform curvature and Poisson (longitudinal, zero shear) gauges.
[ { "created": "Tue, 5 Mar 2019 14:22:46 GMT", "version": "v1" } ]
2019-08-07
[ [ "Uggla", "Claes", "" ], [ "Wainwright", "John", "" ] ]
The study of long wavelength scalar perturbations, in particular the existence of conserved quantities when the perturbations are adiabatic, plays an important role in e.g. inflationary cosmology. In this paper we present some new conserved quantities at second order and relate them to the curvature perturbation in the uniform density gauge, $\zeta$, and the comoving curvature perturbation, ${\cal R}$. We also, for the first time, derive the general solution of the perturbed Einstein equations at second order, which thereby contains both growing and decaying modes, for adiabatic long wavelength perturbations for a stress-energy tensor with zero anisotropic stresses and zero heat flux. The derivation uses the total matter gauge, but results are subsequently translated to the uniform curvature and Poisson (longitudinal, zero shear) gauges.
gr-qc/9304025
null
Arlen Anderson and Jonathan J. Halliwell
An Information-Theoretic Measure of Uncertainty due to Quantum and Thermal Fluctuations
36 pages (revised uncorrupted version), Report IC 92-93/25
Phys.Rev. D48 (1993) 2753-2765
10.1103/PhysRevD.48.2753
null
gr-qc cond-mat hep-th
null
We study an information-theoretic measure of uncertainty for quantum systems. It is the Shannon information $I$ of the phase space probability distribution $\la z | \rho | z \ra $, where $|z \ra $ are coherent states, and $\rho$ is the density matrix. The uncertainty principle is expressed in this measure as $I \ge 1$. For a harmonic oscillator in a thermal state, $I$ coincides with von Neumann entropy, $- \Tr(\rho \ln \rho)$, in the high-temperature regime, but unlike entropy, it is non-zero at zero temperature. It therefore supplies a non-trivial measure of uncertainty due to both quantum and thermal fluctuations. We study $I$ as a function of time for a class of non-equilibrium quantum systems consisting of a distinguished system coupled to a heat bath. We derive an evolution equation for $I$. For the harmonic oscillator, in the Fokker-Planck regime, we show that $I$ increases monotonically. For more general Hamiltonians, $I$ settles down to monotonic increase in the long run, but may suffer an initial decrease for certain initial states that undergo ``reassembly'' (the opposite of quantum spreading). Our main result is to prove, for linear systems, that $I$ at each moment of time has a lower bound $I_t^{min}$, over all possible initial states. This bound is a generalization of the uncertainty principle to include thermal fluctuations in non-equilibrium systems, and represents the least amount of uncertainty the system must suffer after evolution in the presence of an environment for time $t$.
[ { "created": "Sun, 18 Apr 1993 13:32:00 GMT", "version": "v1" }, { "created": "Wed, 21 Apr 1993 10:52:00 GMT", "version": "v2" }, { "created": "Wed, 28 Apr 1993 10:48:54 GMT", "version": "v3" } ]
2009-10-22
[ [ "Anderson", "Arlen", "" ], [ "Halliwell", "Jonathan J.", "" ] ]
We study an information-theoretic measure of uncertainty for quantum systems. It is the Shannon information $I$ of the phase space probability distribution $\la z | \rho | z \ra $, where $|z \ra $ are coherent states, and $\rho$ is the density matrix. The uncertainty principle is expressed in this measure as $I \ge 1$. For a harmonic oscillator in a thermal state, $I$ coincides with von Neumann entropy, $- \Tr(\rho \ln \rho)$, in the high-temperature regime, but unlike entropy, it is non-zero at zero temperature. It therefore supplies a non-trivial measure of uncertainty due to both quantum and thermal fluctuations. We study $I$ as a function of time for a class of non-equilibrium quantum systems consisting of a distinguished system coupled to a heat bath. We derive an evolution equation for $I$. For the harmonic oscillator, in the Fokker-Planck regime, we show that $I$ increases monotonically. For more general Hamiltonians, $I$ settles down to monotonic increase in the long run, but may suffer an initial decrease for certain initial states that undergo ``reassembly'' (the opposite of quantum spreading). Our main result is to prove, for linear systems, that $I$ at each moment of time has a lower bound $I_t^{min}$, over all possible initial states. This bound is a generalization of the uncertainty principle to include thermal fluctuations in non-equilibrium systems, and represents the least amount of uncertainty the system must suffer after evolution in the presence of an environment for time $t$.
gr-qc/0208036
Jose Geraldo Pereira
J.G. Pereira and T. Vargas
Regge Calculus in Teleparallel Gravity
Latex, 10 pages, 2 eps figures, to appear in Class. Quant. Grav
Class.Quant.Grav. 19 (2002) 4807-4816
10.1088/0264-9381/19/19/301
null
gr-qc
null
In the context of the teleparallel equivalent of general relativity, the Weitzenbock manifold is considered as the limit of a suitable sequence of discrete lattices composed of an increasing number of smaller an smaller simplices, where the interior of each simplex (Delaunay lattice) is assumed to be flat. The link lengths between any pair of vertices serve as independent variables, so that torsion turns out to be localized in the two dimensional hypersurfaces (dislocation triangle, or hinge) of the lattice. Assuming that a vector undergoes a dislocation in relation to its initial position as it is parallel transported along the perimeter of the dual lattice (Voronoi polygon), we obtain the discrete analogue of the teleparallel action, as well as the corresponding simplicial vacuum field equations.
[ { "created": "Wed, 14 Aug 2002 12:48:40 GMT", "version": "v1" } ]
2009-11-07
[ [ "Pereira", "J. G.", "" ], [ "Vargas", "T.", "" ] ]
In the context of the teleparallel equivalent of general relativity, the Weitzenbock manifold is considered as the limit of a suitable sequence of discrete lattices composed of an increasing number of smaller an smaller simplices, where the interior of each simplex (Delaunay lattice) is assumed to be flat. The link lengths between any pair of vertices serve as independent variables, so that torsion turns out to be localized in the two dimensional hypersurfaces (dislocation triangle, or hinge) of the lattice. Assuming that a vector undergoes a dislocation in relation to its initial position as it is parallel transported along the perimeter of the dual lattice (Voronoi polygon), we obtain the discrete analogue of the teleparallel action, as well as the corresponding simplicial vacuum field equations.
1905.09260
Francesco Salemi
F. Salemi, E. Milotti, G. A. Prodi, G. Vedovato, C. Lazzaro, S. Tiwari, S. Vinciguerra, M. Drago and S. Klimenko
A wider look at the gravitational-wave transients from GWTC-1 using an unmodeled reconstruction method
13 pages, 7 figures and 3 tables
Phys. Rev. D 100, 042003 (2019)
10.1103/PhysRevD.100.042003
null
gr-qc
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
In this paper, we investigate the morphology of the events from the GWTC-1 catalog of compact binary coalescences as reconstructed by a method based on coherent excess power: we use an open-source version of the coherent WaveBurst (cWB) analysis pipeline, which does not make use of waveform models. The coherent response of the LIGO-Virgo network of detectors is estimated by using loose bounds on the duration and bandwidth of the signal. This pipeline version reproduces the same results that are reported for cWB in recent publications by the LIGO and Virgo collaborations. In particular, the sky localization and waveform reconstruction are in a good agreement with those produced by methods which exploit the detailed theoretical knowledge of the expected waveform for compact binary coalescences. However, in some cases cWB also detects features in excess in well-localized regions of the time-frequency plane. Here we focus on such deviations and present the methods devised to assess their significance. Out of the eleven events reported in the GWTC-1, in two cases -- GW151012 and GW151226 -- cWB detects an excess of coherent energy after the merger ($\Delta t \simeq 0.2$ s and $\simeq 0.1$ s, respectively) with p-values that call for further investigations ($0.004$ and $0.03$, respectively), though they are not sufficient to exclude noise fluctuations. We discuss the morphological properties and plausible interpretations of these features. We believe that the methodology described in the paper shall be useful in future searches for compact binary coalescences.
[ { "created": "Wed, 22 May 2019 17:43:03 GMT", "version": "v1" }, { "created": "Mon, 3 Jun 2019 16:28:02 GMT", "version": "v2" } ]
2019-09-04
[ [ "Salemi", "F.", "" ], [ "Milotti", "E.", "" ], [ "Prodi", "G. A.", "" ], [ "Vedovato", "G.", "" ], [ "Lazzaro", "C.", "" ], [ "Tiwari", "S.", "" ], [ "Vinciguerra", "S.", "" ], [ "Drago", "M.", "" ], [ "Klimenko", "S.", "" ] ]
In this paper, we investigate the morphology of the events from the GWTC-1 catalog of compact binary coalescences as reconstructed by a method based on coherent excess power: we use an open-source version of the coherent WaveBurst (cWB) analysis pipeline, which does not make use of waveform models. The coherent response of the LIGO-Virgo network of detectors is estimated by using loose bounds on the duration and bandwidth of the signal. This pipeline version reproduces the same results that are reported for cWB in recent publications by the LIGO and Virgo collaborations. In particular, the sky localization and waveform reconstruction are in a good agreement with those produced by methods which exploit the detailed theoretical knowledge of the expected waveform for compact binary coalescences. However, in some cases cWB also detects features in excess in well-localized regions of the time-frequency plane. Here we focus on such deviations and present the methods devised to assess their significance. Out of the eleven events reported in the GWTC-1, in two cases -- GW151012 and GW151226 -- cWB detects an excess of coherent energy after the merger ($\Delta t \simeq 0.2$ s and $\simeq 0.1$ s, respectively) with p-values that call for further investigations ($0.004$ and $0.03$, respectively), though they are not sufficient to exclude noise fluctuations. We discuss the morphological properties and plausible interpretations of these features. We believe that the methodology described in the paper shall be useful in future searches for compact binary coalescences.
2311.13138
Behzad Eslam Panah
A. Bagheri Tudeshki, G. H. Bordbar, and B. Eslam Panah
Effect of rainbow function on the structural properties of dark energy star
12 pages, 8 figures, 4 tables
Phys. Lett. B 848 (2024) 138333
10.1016/j.physletb.2023.138333
null
gr-qc hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Confirming the existence of compact objects with a mass greater than $2.5M_{\odot}$ by observational results such as GW190814 makes that is possible to provide theories to justify these observational results using modified gravity. This motivates us to use gravity's rainbow, which is the appropriate case for dense objects, to investigate the dark energy star structure as a suggested alternative case to the mass gap between neutron stars and black holes in the perspective of quantum gravity. Hence, in the present work, we derive the modified hydrostatic equilibrium equation for an anisotropic fluid, represented by the extended Chaplygin equation of state in gravity's rainbow. Then, for two isotropic and anisotropic cases, using the numerical solution, we obtain energy-dependent maximum mass and its corresponding radius, and the other properties of the dark energy star including the pressure, energy density, stability, etc. In the following, using the observational data, we compare the obtained results in two frameworks of general relativity and gravity's rainbow.
[ { "created": "Wed, 22 Nov 2023 03:55:53 GMT", "version": "v1" } ]
2023-11-23
[ [ "Tudeshki", "A. Bagheri", "" ], [ "Bordbar", "G. H.", "" ], [ "Panah", "B. Eslam", "" ] ]
Confirming the existence of compact objects with a mass greater than $2.5M_{\odot}$ by observational results such as GW190814 makes that is possible to provide theories to justify these observational results using modified gravity. This motivates us to use gravity's rainbow, which is the appropriate case for dense objects, to investigate the dark energy star structure as a suggested alternative case to the mass gap between neutron stars and black holes in the perspective of quantum gravity. Hence, in the present work, we derive the modified hydrostatic equilibrium equation for an anisotropic fluid, represented by the extended Chaplygin equation of state in gravity's rainbow. Then, for two isotropic and anisotropic cases, using the numerical solution, we obtain energy-dependent maximum mass and its corresponding radius, and the other properties of the dark energy star including the pressure, energy density, stability, etc. In the following, using the observational data, we compare the obtained results in two frameworks of general relativity and gravity's rainbow.
1910.13897
Antonio Gallerati
Giovanni Alberto Ummarino, Antonio Gallerati
Exploiting weak field gravity-Maxwell symmetry in superconductive fluctuations regime
14 pages, 3 figures
Symmetry 11 (2019) 11, 1341
10.3390/sym11111341
null
gr-qc cond-mat.supr-con hep-ph
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
We study the behaviour of a superconductor in a weak static gravitational field for temperatures slightly greater than its transition temperature (fluctuation regime). Making use of the time-dependent Ginzburg-Landau equations, we find a possible short time alteration of the static gravitational field in the vicinity of the superconductor, providing also a qualitative behaviour in the weak field condition. Finally, we compare the behaviour of various superconducting materials, investigating which parameters could enhance the gravitational field alteration.
[ { "created": "Wed, 30 Oct 2019 14:40:10 GMT", "version": "v1" }, { "created": "Thu, 21 Nov 2019 16:40:37 GMT", "version": "v2" }, { "created": "Mon, 25 Nov 2019 15:09:15 GMT", "version": "v3" }, { "created": "Thu, 28 Nov 2019 14:12:26 GMT", "version": "v4" }, { "created": "Wed, 15 Apr 2020 17:49:13 GMT", "version": "v5" }, { "created": "Tue, 18 May 2021 08:52:13 GMT", "version": "v6" } ]
2021-05-19
[ [ "Ummarino", "Giovanni Alberto", "" ], [ "Gallerati", "Antonio", "" ] ]
We study the behaviour of a superconductor in a weak static gravitational field for temperatures slightly greater than its transition temperature (fluctuation regime). Making use of the time-dependent Ginzburg-Landau equations, we find a possible short time alteration of the static gravitational field in the vicinity of the superconductor, providing also a qualitative behaviour in the weak field condition. Finally, we compare the behaviour of various superconducting materials, investigating which parameters could enhance the gravitational field alteration.
2306.03676
Jose Wadih Maluf Dr.
J. W. Maluf, F. L. Carneiro, S. C. Ulhoa and J. F. da Rocha-Neto
Tetrad Fields, Reference Frames, and the Gravitational Energy-Momentum in the Teleparallel Equivalent of General Relativity
66 pages, 5 figures. Published in the Annalen der Physik. In this version, we have only fixed some typos and made linguistic corrections. Several paragraphs and comments were added to the published article, but are not displayed here due to copyright restrictions
Ann. Phys. (Berlin) 2023, 2300241
10.1002/andp.202300241
null
gr-qc
http://creativecommons.org/licenses/by/4.0/
We review the concept and definitions of the energy-momentum and angular momentum of the gravitational field in the teleparallel equivalent of general relativity (TEGR). The importance of these definitions is justified by three major reasons. First, the TEGR is a well established and widely accepted formulation of the gravitational field, whose basic field strength is the torsion tensor of the Weitzenb\"ock connection. Second, in the phase space of the TEGR there exists an algebra of the Poincar\'e group. Not only the definitions of the gravitational energy-momentum and 4-angular momentum satisfy this algebra, but also the first class constraints related to these definitions satisfy the algebra. And third, numerous applications of these definitions lead to physically consistent results. These definitions follow from a well established Hamiltonian formulation, and rely on the idea of localization of the gravitational energy. In this review we revisit the concept of localizability of the gravitational energy, in light of results obtained in recent years. We have studied the behaviour of free particles in the space-time of plane fronted gravitational waves (pp-waves). Free particles are here understood as particles that are not subject to external forces other than the gravitational acceleration due to pp-waves. Since these particles acquire or loose kinetic energy locally, the transfer of energy from or to the gravitational field must also be localized. We consider this theoretical result an important and definite argument in favour of the localization of the gravitational energy-momentum, and by extension, of the gravitational 4-angular momentum.
[ { "created": "Tue, 6 Jun 2023 13:40:37 GMT", "version": "v1" }, { "created": "Tue, 21 Nov 2023 13:40:45 GMT", "version": "v2" } ]
2023-11-22
[ [ "Maluf", "J. W.", "" ], [ "Carneiro", "F. L.", "" ], [ "Ulhoa", "S. C.", "" ], [ "da Rocha-Neto", "J. F.", "" ] ]
We review the concept and definitions of the energy-momentum and angular momentum of the gravitational field in the teleparallel equivalent of general relativity (TEGR). The importance of these definitions is justified by three major reasons. First, the TEGR is a well established and widely accepted formulation of the gravitational field, whose basic field strength is the torsion tensor of the Weitzenb\"ock connection. Second, in the phase space of the TEGR there exists an algebra of the Poincar\'e group. Not only the definitions of the gravitational energy-momentum and 4-angular momentum satisfy this algebra, but also the first class constraints related to these definitions satisfy the algebra. And third, numerous applications of these definitions lead to physically consistent results. These definitions follow from a well established Hamiltonian formulation, and rely on the idea of localization of the gravitational energy. In this review we revisit the concept of localizability of the gravitational energy, in light of results obtained in recent years. We have studied the behaviour of free particles in the space-time of plane fronted gravitational waves (pp-waves). Free particles are here understood as particles that are not subject to external forces other than the gravitational acceleration due to pp-waves. Since these particles acquire or loose kinetic energy locally, the transfer of energy from or to the gravitational field must also be localized. We consider this theoretical result an important and definite argument in favour of the localization of the gravitational energy-momentum, and by extension, of the gravitational 4-angular momentum.
2001.04978
Vesselin G. Gueorguiev
Andre Maeder and Vesselin G. Gueorguiev
Scale-Invariant Dynamics of Galaxies, MOND, Dark Matter, and the Dwarf Spheroidals
12 pages, 3 figures
null
10.1093/mnras/stz3613
null
gr-qc astro-ph.GA
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
The Scale-Invariant Vacuum (SIV) theory is based on Weyl's Integrable Geometry, endowed with a gauge scalar field. The main difference between MOND and the SIV theory is that the first considers a global dilatation invariance of space and time, where the scale factor $\lambda$ is a constant, while the second opens the likely possibility that $\lambda$ is a function of time. The key equations of the SIV framework are used here to study the relationship between the Newtonian gravitational acceleration due to baryonic matter $g_{\mathrm{bar}}$ and the observed kinematical acceleration $g_{\mathrm{obs}}$. The relationship is applied to galactic systems of the same age where the Radial Acceleration Relation (RAR), between the $g_{\mathrm{obs}}$ and $g_{\mathrm{bar}}$ accelerations, can be compared with observational data. The SIV theory shows an excellent agreement with observations and with MOND for baryonic gravities $g_{\mathrm{bar}}>10^{-11.5}$ m s$^{-2}$. Below this value, SIV still fully agrees with the observations, as well as with the horizontal asymptote of the RAR for dwarf spheroidals, while this is not the case for MOND. These results support the view that there is no need for dark matter and that the RAR and related dynamical properties of galaxies can be interpreted by a modification of gravitation.
[ { "created": "Tue, 14 Jan 2020 07:19:59 GMT", "version": "v1" } ]
2020-01-16
[ [ "Maeder", "Andre", "" ], [ "Gueorguiev", "Vesselin G.", "" ] ]
The Scale-Invariant Vacuum (SIV) theory is based on Weyl's Integrable Geometry, endowed with a gauge scalar field. The main difference between MOND and the SIV theory is that the first considers a global dilatation invariance of space and time, where the scale factor $\lambda$ is a constant, while the second opens the likely possibility that $\lambda$ is a function of time. The key equations of the SIV framework are used here to study the relationship between the Newtonian gravitational acceleration due to baryonic matter $g_{\mathrm{bar}}$ and the observed kinematical acceleration $g_{\mathrm{obs}}$. The relationship is applied to galactic systems of the same age where the Radial Acceleration Relation (RAR), between the $g_{\mathrm{obs}}$ and $g_{\mathrm{bar}}$ accelerations, can be compared with observational data. The SIV theory shows an excellent agreement with observations and with MOND for baryonic gravities $g_{\mathrm{bar}}>10^{-11.5}$ m s$^{-2}$. Below this value, SIV still fully agrees with the observations, as well as with the horizontal asymptote of the RAR for dwarf spheroidals, while this is not the case for MOND. These results support the view that there is no need for dark matter and that the RAR and related dynamical properties of galaxies can be interpreted by a modification of gravitation.
1006.1863
Paolo Pani
Paolo Pani, Enrico Barausse, Emanuele Berti, Vitor Cardoso
Gravitational instabilities of superspinars
15 pages, 9 figures, 1 table. v2: Fig. 8 and Section I improved. v3: minor changes to match the published version
Phys.Rev.D82:044009,2010
10.1103/PhysRevD.82.044009
null
gr-qc astro-ph.HE hep-th
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Superspinars are ultracompact objects whose mass M and angular momentum J violate the Kerr bound (cJ/GM^2>1). Recent studies analyzed the observable consequences of gravitational lensing and accretion around superspinars in astrophysical scenarios. In this paper we investigate the dynamical stability of superspinars to gravitational perturbations, considering either purely reflecting or perfectly absorbing boundary conditions at the "surface" of the superspinar. We find that these objects are unstable independently of the boundary conditions, and that the instability is strongest for relatively small values of the spin. Also, we give a physical interpretation of the various instabilities that we find. Our results (together with the well-known fact that accretion tends to spin superspinars down) imply that superspinars are very unlikely astrophysical alternatives to black holes.
[ { "created": "Wed, 9 Jun 2010 17:36:18 GMT", "version": "v1" }, { "created": "Thu, 29 Jul 2010 06:59:31 GMT", "version": "v2" }, { "created": "Mon, 9 Aug 2010 11:55:23 GMT", "version": "v3" } ]
2014-11-21
[ [ "Pani", "Paolo", "" ], [ "Barausse", "Enrico", "" ], [ "Berti", "Emanuele", "" ], [ "Cardoso", "Vitor", "" ] ]
Superspinars are ultracompact objects whose mass M and angular momentum J violate the Kerr bound (cJ/GM^2>1). Recent studies analyzed the observable consequences of gravitational lensing and accretion around superspinars in astrophysical scenarios. In this paper we investigate the dynamical stability of superspinars to gravitational perturbations, considering either purely reflecting or perfectly absorbing boundary conditions at the "surface" of the superspinar. We find that these objects are unstable independently of the boundary conditions, and that the instability is strongest for relatively small values of the spin. Also, we give a physical interpretation of the various instabilities that we find. Our results (together with the well-known fact that accretion tends to spin superspinars down) imply that superspinars are very unlikely astrophysical alternatives to black holes.