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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
2302.05683 | Vasiliy P. Neznamov | V.P.Neznamov | Quantum probing of singularities at event horizons of black holes | 19 pages | International Journal of Modern Physics A 36 (2021) 2150147 | 10.1142/S0217751X21501475 | null | gr-qc hep-th | http://creativecommons.org/publicdomain/zero/1.0/ | It is proved that coordinate transformations of the Schwarzschild metric to
new static and stationary metrics do not eliminate the mode of a particle
''fall'' to the event horizon of a black hole. This mode is unacceptable for
the quantum mechanics of stationary states.
| [
{
"created": "Sat, 11 Feb 2023 12:39:31 GMT",
"version": "v1"
}
] | 2023-02-14 | [
[
"Neznamov",
"V. P.",
""
]
] | It is proved that coordinate transformations of the Schwarzschild metric to new static and stationary metrics do not eliminate the mode of a particle ''fall'' to the event horizon of a black hole. This mode is unacceptable for the quantum mechanics of stationary states. |
2207.14531 | Naimi Takka | N. Takka and A. Bouda | Maxwell's equations and Lorentz force in doubly special relativity | null | Indian J Phys 94, 1227 (2020) | 10.1007/s12648-019-01556-x | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | On the basis of all commutation relations of the k-deformed phase space
incorporating the k-Minkowski space-time, we have derived in this paper an
extended first approximation of both Maxwell's equations and Lorentz force in
doubly (or deformed) special relativity (DSR). For this purpose, we have used
our approach of the special relativistic version of Feynman's proof by which we
have established the explicit formulations of electric and magnetic fields. As
in Fock's nonlinear relativity (FNLR), the laws of electrodynamics depend on
the particle mass which therefore constitutes a common point between the two
extended forms of special relativity. As one consequence, the corresponding
equation of motion contains two different types of contributions. In addition
to the usual type, another one emerges as a consequence of the coexistence of
mass and charge which are coupled with the k-deformation and electromagnetic
field. This new effect completely induced by the k-deformed phase space is
interpreted as the gravitational-type Lorentz force. Unlike FNLR, the
corrective terms all depend on the electromagnetic field in DSR.
| [
{
"created": "Fri, 29 Jul 2022 07:57:44 GMT",
"version": "v1"
}
] | 2022-08-01 | [
[
"Takka",
"N.",
""
],
[
"Bouda",
"A.",
""
]
] | On the basis of all commutation relations of the k-deformed phase space incorporating the k-Minkowski space-time, we have derived in this paper an extended first approximation of both Maxwell's equations and Lorentz force in doubly (or deformed) special relativity (DSR). For this purpose, we have used our approach of the special relativistic version of Feynman's proof by which we have established the explicit formulations of electric and magnetic fields. As in Fock's nonlinear relativity (FNLR), the laws of electrodynamics depend on the particle mass which therefore constitutes a common point between the two extended forms of special relativity. As one consequence, the corresponding equation of motion contains two different types of contributions. In addition to the usual type, another one emerges as a consequence of the coexistence of mass and charge which are coupled with the k-deformation and electromagnetic field. This new effect completely induced by the k-deformed phase space is interpreted as the gravitational-type Lorentz force. Unlike FNLR, the corrective terms all depend on the electromagnetic field in DSR. |
1207.3621 | Jaume Haro | Jaume de Haro | Does loop quantum cosmology replace the big rip singularity by a
non-singular bounce? | Accepted for publication in JCAP | JCAP 07 (11) 2012 | 10.1088/1475-7516/2012/11/037 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is stated that holonomy corrections in loop quantum cosmology introduce a
modification in Friedmann's equation which prevent the big rip singularity.
Recently in \cite{h12} it has been proved that this modified Friedmann equation
is obtained in an inconsistent way, what means that the results deduced from
it, in particular the big rip singularity avoidance, are not justified. The
problem is that holonomy corrections modify the gravitational part of the
Hamiltonian of the system leading, after Legendre's transformation, to a non
covariant Lagrangian which is in contradiction with one of the main principles
of General Relativity. A more consistent way to deal with the big rip
singularity avoidance is to disregard modification in the gravitational part of
the Hamiltonian, and only consider inverse volume effects \cite{bo02a}. In this
case we will see that, not like the big bang singularity, the big rip
singularity survives in loop quantum cosmology. Another way to deal with the
big rip avoidance is to take into account geometric quantum effects given by
the the Wheeler-De Witt equation. In that case, even though the wave packets
spread, the expectation values satisfy the same equations as their classical
analogues. Then, following the viewpoint adopted in loop quantum cosmology, one
can conclude that the big rip singularity survives when one takes into account
these quantum effects. However, the spreading of the wave packets prevents the
recover of the semiclassical time, and thus, one might conclude that the
classical evolution of the universe come to and end before the big rip is
reached. This is not conclusive because. as we will see, it always exists other
external times that allows us to define the classical and quantum evolution of
the universe up to the big rip singularity.
| [
{
"created": "Mon, 16 Jul 2012 10:20:50 GMT",
"version": "v1"
},
{
"created": "Tue, 6 Nov 2012 08:17:28 GMT",
"version": "v2"
}
] | 2014-09-05 | [
[
"de Haro",
"Jaume",
""
]
] | It is stated that holonomy corrections in loop quantum cosmology introduce a modification in Friedmann's equation which prevent the big rip singularity. Recently in \cite{h12} it has been proved that this modified Friedmann equation is obtained in an inconsistent way, what means that the results deduced from it, in particular the big rip singularity avoidance, are not justified. The problem is that holonomy corrections modify the gravitational part of the Hamiltonian of the system leading, after Legendre's transformation, to a non covariant Lagrangian which is in contradiction with one of the main principles of General Relativity. A more consistent way to deal with the big rip singularity avoidance is to disregard modification in the gravitational part of the Hamiltonian, and only consider inverse volume effects \cite{bo02a}. In this case we will see that, not like the big bang singularity, the big rip singularity survives in loop quantum cosmology. Another way to deal with the big rip avoidance is to take into account geometric quantum effects given by the the Wheeler-De Witt equation. In that case, even though the wave packets spread, the expectation values satisfy the same equations as their classical analogues. Then, following the viewpoint adopted in loop quantum cosmology, one can conclude that the big rip singularity survives when one takes into account these quantum effects. However, the spreading of the wave packets prevents the recover of the semiclassical time, and thus, one might conclude that the classical evolution of the universe come to and end before the big rip is reached. This is not conclusive because. as we will see, it always exists other external times that allows us to define the classical and quantum evolution of the universe up to the big rip singularity. |
gr-qc/9912045 | Eric Poisson | Eric Poisson | An introduction to the Lorentz-Dirac equation | 14 pages, ReVTeX, 3 figures | null | null | null | gr-qc | null | These notes provide two derivations of the Lorentz-Dirac equation. The first
is patterned after Landau and Lifshitz and is based on the observation that the
half-retarded minus half-advanced potential is entirely responsible for the
radiation-reaction force. The second is patterned after Dirac, and is based
upon considerations of energy-momentum conservation; it relies exclusively on
the retarded potential. The notes conclude with a discussion of the
difficulties associated with the interpretation of the Lorentz-Dirac equation
as an equation of motion for a point charge. The presentation is essentially
self-contained, but the reader is assumed to possess some elements of
differential geometry (necessary for the second derivation only).
| [
{
"created": "Fri, 10 Dec 1999 20:38:51 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Poisson",
"Eric",
""
]
] | These notes provide two derivations of the Lorentz-Dirac equation. The first is patterned after Landau and Lifshitz and is based on the observation that the half-retarded minus half-advanced potential is entirely responsible for the radiation-reaction force. The second is patterned after Dirac, and is based upon considerations of energy-momentum conservation; it relies exclusively on the retarded potential. The notes conclude with a discussion of the difficulties associated with the interpretation of the Lorentz-Dirac equation as an equation of motion for a point charge. The presentation is essentially self-contained, but the reader is assumed to possess some elements of differential geometry (necessary for the second derivation only). |
gr-qc/0611061 | E. Kyriakopoulos | E. Kyriakopoulos | Black Holes in Models with Dilaton Field and Electric or Electric and
Magnetic Charges | 16 pages. Accepted for publication in CQG | Class.Quant.Grav.23:7591-7602,2006 | 10.1088/0264-9381/23/24/027 | null | gr-qc | null | Exact static spherically symmetric charged black holes in four dimensions are
presented. One of them has only electric charge and another electric and
magnetic charges. In these solutions the metric is asymptotically flat, has two
horizons, irremovable singularity only at $r=0$, and the dilaton field is
singular only at $r=0$. The solution with electric charge only is characterized
by three free parameters, the ADM mass, the electric charge and an additional
free parameter. It can be considered as a modification of the GHS-GM solution
obtained by changing the coupling between dilaton and electromagnetic field.
The general dyonic solution is again characterized by three free parameters,
the ADM mass, the magnetic charge and an additional free parameter, which is
not the electric charge. According to a definition of the no-hair conjecture
the solutions are "hairy".A very interesting special case of the dyonic
solution is characterized by three free parameters, the ADM mass and the
electric and the magnetic charges. The solutions satisfy the dominant as well
as the strong energy condition outside and on the external horizon.
| [
{
"created": "Fri, 10 Nov 2006 20:06:11 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Kyriakopoulos",
"E.",
""
]
] | Exact static spherically symmetric charged black holes in four dimensions are presented. One of them has only electric charge and another electric and magnetic charges. In these solutions the metric is asymptotically flat, has two horizons, irremovable singularity only at $r=0$, and the dilaton field is singular only at $r=0$. The solution with electric charge only is characterized by three free parameters, the ADM mass, the electric charge and an additional free parameter. It can be considered as a modification of the GHS-GM solution obtained by changing the coupling between dilaton and electromagnetic field. The general dyonic solution is again characterized by three free parameters, the ADM mass, the magnetic charge and an additional free parameter, which is not the electric charge. According to a definition of the no-hair conjecture the solutions are "hairy".A very interesting special case of the dyonic solution is characterized by three free parameters, the ADM mass and the electric and the magnetic charges. The solutions satisfy the dominant as well as the strong energy condition outside and on the external horizon. |
1210.8106 | \"Ozg\"ur Akarsu | Ozgur Akarsu, Tekin Dereli | Late Time Acceleration of the 3-Space in a Higher Dimensional Steady
State Universe in Dilaton Gravity | 30 pages, 19 figures, 3 tables; improved significantly; the version
accepted for publication in Journal of Cosmology and Astroparticle Physics
(JCAP) | JCAP 02 (2013) 050 | 10.1088/1475-7516/2013/02/050 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present cosmological solutions for (1+3+n)-dimensional steady state
universe in dilaton gravity with an arbitrary dilaton coupling constant w and
exponential dilaton self-interaction potentials in the string frame. We focus
particularly on the class in which the 3-space expands with a time varying
deceleration parameter. We discuss the number of the internal dimensions and
the value of the dilaton coupling constant to determine the cases that are
consistent with the observed universe and the primordial nucleosynthesis. The
3-space starts with a decelerated expansion rate and evolves into accelerated
expansion phase subject to the values of w and n, but ends with a Big Rip in
all cases. We discuss the cosmological evolution in further detail for the
cases w=1 and w=1/2 that permit exact solutions. We also comment on how the
universe would be conceived by an observer in four dimensions who is unaware of
the internal dimensions and thinks that the conventional general relativity is
valid at cosmological scales.
| [
{
"created": "Tue, 30 Oct 2012 18:15:34 GMT",
"version": "v1"
},
{
"created": "Mon, 11 Feb 2013 11:01:59 GMT",
"version": "v2"
}
] | 2013-03-01 | [
[
"Akarsu",
"Ozgur",
""
],
[
"Dereli",
"Tekin",
""
]
] | We present cosmological solutions for (1+3+n)-dimensional steady state universe in dilaton gravity with an arbitrary dilaton coupling constant w and exponential dilaton self-interaction potentials in the string frame. We focus particularly on the class in which the 3-space expands with a time varying deceleration parameter. We discuss the number of the internal dimensions and the value of the dilaton coupling constant to determine the cases that are consistent with the observed universe and the primordial nucleosynthesis. The 3-space starts with a decelerated expansion rate and evolves into accelerated expansion phase subject to the values of w and n, but ends with a Big Rip in all cases. We discuss the cosmological evolution in further detail for the cases w=1 and w=1/2 that permit exact solutions. We also comment on how the universe would be conceived by an observer in four dimensions who is unaware of the internal dimensions and thinks that the conventional general relativity is valid at cosmological scales. |
1011.3022 | David Brizuela | Martin Bojowald, David Brizuela, Hector H. Hernandez, Michael J. Koop,
Hugo A. Morales-Tecotl | High-order quantum back-reaction and quantum cosmology with a positive
cosmological constant | 21 pages, 11 figures. Several clarifications, four references, and a
new appendix added. Version accepted for publication in PRD | Phys.Rev.D84:043514,2011 | 10.1103/PhysRevD.84.043514 | IGC-10/11-2 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | When quantum back-reaction by fluctuations, correlations and higher moments
of a state becomes strong, semiclassical quantum mechanics resembles a
dynamical system with a high-dimensional phase space. Here, systematic
computational methods to derive the dynamical equations including all quantum
corrections to high order in the moments are introduced, together with a
(deparameterized) quantum cosmological example to illustrate some implications.
The results show, for instance, that the Gaussian form of an initial state is
maintained only briefly, but that the evolving state settles down to a new
characteristic shape afterwards. Remarkably, even in the regime of large
high-order moments, we observe a strong convergence within all considered
orders that supports the use of this effective approach.
| [
{
"created": "Fri, 12 Nov 2010 20:08:33 GMT",
"version": "v1"
},
{
"created": "Mon, 12 Sep 2011 15:52:24 GMT",
"version": "v2"
}
] | 2011-09-13 | [
[
"Bojowald",
"Martin",
""
],
[
"Brizuela",
"David",
""
],
[
"Hernandez",
"Hector H.",
""
],
[
"Koop",
"Michael J.",
""
],
[
"Morales-Tecotl",
"Hugo A.",
""
]
] | When quantum back-reaction by fluctuations, correlations and higher moments of a state becomes strong, semiclassical quantum mechanics resembles a dynamical system with a high-dimensional phase space. Here, systematic computational methods to derive the dynamical equations including all quantum corrections to high order in the moments are introduced, together with a (deparameterized) quantum cosmological example to illustrate some implications. The results show, for instance, that the Gaussian form of an initial state is maintained only briefly, but that the evolving state settles down to a new characteristic shape afterwards. Remarkably, even in the regime of large high-order moments, we observe a strong convergence within all considered orders that supports the use of this effective approach. |
1510.02751 | Leonid Perlov | Leonid Perlov, Michael Bukatin | Barbero-Immirzi parameter as a solution of the simplicity constraints | The other paper was written and published, which includes this one.
The result was more general | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we naturally obtain the values of the Barbero-Immirzi parameter
as the solution of the simplicity constraints rather than setting it a priori.
Particularly the Main theorem shows that if $\gamma = \pm i$ then the
simplicity constraints require that the corresponding Lorentz group
representations be necessary finite dimensional and therefore non-unitary.
| [
{
"created": "Fri, 9 Oct 2015 18:05:25 GMT",
"version": "v1"
},
{
"created": "Sun, 1 Nov 2015 15:38:23 GMT",
"version": "v2"
},
{
"created": "Wed, 25 Nov 2015 14:57:57 GMT",
"version": "v3"
},
{
"created": "Wed, 24 May 2017 15:57:42 GMT",
"version": "v4"
}
] | 2017-05-25 | [
[
"Perlov",
"Leonid",
""
],
[
"Bukatin",
"Michael",
""
]
] | In this paper we naturally obtain the values of the Barbero-Immirzi parameter as the solution of the simplicity constraints rather than setting it a priori. Particularly the Main theorem shows that if $\gamma = \pm i$ then the simplicity constraints require that the corresponding Lorentz group representations be necessary finite dimensional and therefore non-unitary. |
1202.0540 | Abraham Harte | Abraham I. Harte, Theodore D. Drivas | Caustics and wave propagation in curved spacetimes | 34 pages, 7 figures, fixed typos | Phys. Rev. D 85, 124039 (2012) | 10.1103/PhysRevD.85.124039 | AEI-2012-041 | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the effects of light cone caustics on the propagation of
linear scalar fields in generic four-dimensional spacetimes. In particular, we
analyze the singular structure of relevant Green functions. As expected from
general theorems, Green functions associated with wave equations are globally
singular along a large class of null geodesics. Despite this, the "nature" of
the singularity on a given geodesic does not necessarily remain fixed. It can
change character on encountering caustics of the light cone. These changes are
studied by first deriving global Green functions for scalar fields propagating
on smooth plane wave spacetimes. We then use Penrose limits to argue that there
is a sense in which the "leading order singular behavior" of a (typically
unknown) Green function associated with a generic spacetime can always be
understood using a (known) Green function associated with an appropriate plane
wave spacetime. This correspondence is used to derive a simple rule describing
how Green functions change their singular structure near some reference null
geodesic. Such changes depend only on the multiplicities of the conjugate
points encountered along the reference geodesic. Using sigma(p,p') to denote a
suitable generalization of Synge's world function, conjugate points with
multiplicity 1 convert Green function singularities involving delta(sigma) into
singularities involving 1/pi sigma (and vice-versa). Conjugate points with
multiplicity 2 may be viewed as having the effect of two successive passes
through conjugate points with multiplicity 1.
| [
{
"created": "Thu, 2 Feb 2012 20:40:10 GMT",
"version": "v1"
},
{
"created": "Wed, 9 May 2012 12:22:51 GMT",
"version": "v2"
},
{
"created": "Wed, 6 Jun 2012 13:56:22 GMT",
"version": "v3"
}
] | 2012-07-09 | [
[
"Harte",
"Abraham I.",
""
],
[
"Drivas",
"Theodore D.",
""
]
] | We investigate the effects of light cone caustics on the propagation of linear scalar fields in generic four-dimensional spacetimes. In particular, we analyze the singular structure of relevant Green functions. As expected from general theorems, Green functions associated with wave equations are globally singular along a large class of null geodesics. Despite this, the "nature" of the singularity on a given geodesic does not necessarily remain fixed. It can change character on encountering caustics of the light cone. These changes are studied by first deriving global Green functions for scalar fields propagating on smooth plane wave spacetimes. We then use Penrose limits to argue that there is a sense in which the "leading order singular behavior" of a (typically unknown) Green function associated with a generic spacetime can always be understood using a (known) Green function associated with an appropriate plane wave spacetime. This correspondence is used to derive a simple rule describing how Green functions change their singular structure near some reference null geodesic. Such changes depend only on the multiplicities of the conjugate points encountered along the reference geodesic. Using sigma(p,p') to denote a suitable generalization of Synge's world function, conjugate points with multiplicity 1 convert Green function singularities involving delta(sigma) into singularities involving 1/pi sigma (and vice-versa). Conjugate points with multiplicity 2 may be viewed as having the effect of two successive passes through conjugate points with multiplicity 1. |
1601.07921 | De-Chang Dai | De-Chang Dai, Dejan Stojkovic | Pre-Hawking radiation may allow for reconstruction of the mass
distribution of the collapsing object | 4 figures, 5 page, accepted by PLB | Physics Letters B, 758 , pp. 429-433 (2016) | 10.1016/j.physletb.2016.05.037 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Hawking radiation explicitly depends only on the black hole's total mass,
charge and angular momentum. It is therefore generally believed that one cannot
reconstruct the information about the initial mass distribution of an object
that made the black hole. However, instead of looking at radiation from a
static black hole, we can study the whole time-dependent process of the
gravitational collapse, and pre-Hawking radiation which is excited because of
the time-dependent metric. We compare radiation emitted by a single collapsing
shell with that emitted by two concentric shells of the equivalent total mass.
We calculate the gravitational trajectory and the momentum energy tensor. We
show that the flux of energy emitted during the collapse by a single shell is
significantly different from the flux emitted by two concentric shells of the
equivalent total mass. When the static black hole is formed, the fluxes become
indistinguishable. This implies that an observer studying the flux of particles
from a collapsing object could in principle reconstruct information not only
about the total mass of the collapsing object, but also about the mass
distribution.
| [
{
"created": "Tue, 26 Jan 2016 05:10:56 GMT",
"version": "v1"
},
{
"created": "Fri, 13 May 2016 01:26:44 GMT",
"version": "v2"
}
] | 2016-05-31 | [
[
"Dai",
"De-Chang",
""
],
[
"Stojkovic",
"Dejan",
""
]
] | Hawking radiation explicitly depends only on the black hole's total mass, charge and angular momentum. It is therefore generally believed that one cannot reconstruct the information about the initial mass distribution of an object that made the black hole. However, instead of looking at radiation from a static black hole, we can study the whole time-dependent process of the gravitational collapse, and pre-Hawking radiation which is excited because of the time-dependent metric. We compare radiation emitted by a single collapsing shell with that emitted by two concentric shells of the equivalent total mass. We calculate the gravitational trajectory and the momentum energy tensor. We show that the flux of energy emitted during the collapse by a single shell is significantly different from the flux emitted by two concentric shells of the equivalent total mass. When the static black hole is formed, the fluxes become indistinguishable. This implies that an observer studying the flux of particles from a collapsing object could in principle reconstruct information not only about the total mass of the collapsing object, but also about the mass distribution. |
2107.00457 | Zoe Wyatt | David Fajman, Maximilian Ofner, Zoe Wyatt | Slowly expanding stable dust spacetimes | null | null | null | null | gr-qc math.AP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We establish the future nonlinear stability of a large class of FLRW models
as solutions to the Einstein-Dust system. We consider the case of a vanishing
cosmological constant, which in particular implies that the expansion rate of
the respective models is linear i.e. has zero acceleration. The resulting
spacetimes are future globally regular. These solutions constitute the first
generic class of future regular Einstein-Dust spacetimes not undergoing
accelerated expansion and are thereby the slowest expanding generic family of
future complete Einstein-Dust spacetimes currently known.
| [
{
"created": "Thu, 1 Jul 2021 14:07:56 GMT",
"version": "v1"
}
] | 2021-07-02 | [
[
"Fajman",
"David",
""
],
[
"Ofner",
"Maximilian",
""
],
[
"Wyatt",
"Zoe",
""
]
] | We establish the future nonlinear stability of a large class of FLRW models as solutions to the Einstein-Dust system. We consider the case of a vanishing cosmological constant, which in particular implies that the expansion rate of the respective models is linear i.e. has zero acceleration. The resulting spacetimes are future globally regular. These solutions constitute the first generic class of future regular Einstein-Dust spacetimes not undergoing accelerated expansion and are thereby the slowest expanding generic family of future complete Einstein-Dust spacetimes currently known. |
gr-qc/0611033 | Sergey S. Kokarev | Anna Astakhova, Kirill Goodz, Sergey Kokarev | P-Structures, P-Geometry and Observer's Perceptive Space | 6 figures, 4 tables, submitted to Grav. and Cosm | Collected Articles of RSEC "Logos" (2006) v1, pp.73-106 (In
Russian) | null | null | gr-qc | null | Mathematical theory of an observer is elaborated upon the basis of
A.Poincare's ideas on the nature of geometry and the role of observer's
perceptive space. The said theory is generalizing reference frames theory in
GR. Physical structure (P-structure) and corresponding physical geometry
(P-geometry) notions, representing properties invariance of some physical
objects and their relations, are introduced. P-structure of classical physical
time and its corresponding chronogeometry is considered as an example. Some
quantitative characteristics of observer's visual space geometry are
experimentally determined. The affine model of visual geometry is offered to
interpret experimentally sampled data. The connection of the obtained results
with some problems of theoretical physics is being discussed.
| [
{
"created": "Sun, 5 Nov 2006 14:04:41 GMT",
"version": "v1"
}
] | 2008-10-30 | [
[
"Astakhova",
"Anna",
""
],
[
"Goodz",
"Kirill",
""
],
[
"Kokarev",
"Sergey",
""
]
] | Mathematical theory of an observer is elaborated upon the basis of A.Poincare's ideas on the nature of geometry and the role of observer's perceptive space. The said theory is generalizing reference frames theory in GR. Physical structure (P-structure) and corresponding physical geometry (P-geometry) notions, representing properties invariance of some physical objects and their relations, are introduced. P-structure of classical physical time and its corresponding chronogeometry is considered as an example. Some quantitative characteristics of observer's visual space geometry are experimentally determined. The affine model of visual geometry is offered to interpret experimentally sampled data. The connection of the obtained results with some problems of theoretical physics is being discussed. |
2211.03465 | Juan Calderon Bustillo | Juan Calder\'on Bustillo, Samson H.W. Leong and Koustav Chandra | GW190412: measuring a black-hole recoil direction through higher-order
gravitational-wave modes | 8 pages, 4 figures | null | null | LIGO DCC - P2200332 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | General relativity predicts that gravitational waves (GWs) carry linear
momentum. Consequently, the remnant black hole of a black-hole merger can
inherit a recoil velocity or ``kick'' of crucial implications in, e.g,
black-hole formation scenarios. While the kick magnitude is determined by the
mass ratio and spins of the source, estimating its direction requires a
measurement of the two orientation angles of the source. While the orbital
inclination angle is commonly reported in GW observations, the azimuthal one
has been to date ignored. We show how the presence of more than one GW emission
mode allows constraining this angle and, consequently, determines the kick
direction in a real GW event. %We show that the higher-order mode content
GW190412 enables the determination of both these angles and, consequently, the
kick direction. We analyse the GW190412 signal, which contains higher-order
modes, with a numerical-relativity surrogate waveform model for black-hole
mergers. We find that while GW190412 is barely informative about the kick
magnitude, we can constrain its direction. This forms angles
$\theta_{KL}^{\text{-100M}}=28^{+23}_{-11}\,\deg$ with the orbital angular
momentum defined at a reference time $t_{\rm ref}=-100\,M$ before merger (being
preferentially kicked upwards), $\theta_{KN}=37^{+15}_{-12}\,\deg$ with the
line-of-sight and $\phi_{KN}^{\text{-100M}}=46^{+32}_{-41}\,\deg$ with the
projection of the latter onto the former, all at the $68\%$ credible level. We
briefly discuss the potential application of this type of measurement for
multi-messenger observations of black-hole mergers occurring in Active Galactic
Nuclei.
| [
{
"created": "Mon, 7 Nov 2022 11:27:19 GMT",
"version": "v1"
}
] | 2022-11-08 | [
[
"Bustillo",
"Juan Calderón",
""
],
[
"Leong",
"Samson H. W.",
""
],
[
"Chandra",
"Koustav",
""
]
] | General relativity predicts that gravitational waves (GWs) carry linear momentum. Consequently, the remnant black hole of a black-hole merger can inherit a recoil velocity or ``kick'' of crucial implications in, e.g, black-hole formation scenarios. While the kick magnitude is determined by the mass ratio and spins of the source, estimating its direction requires a measurement of the two orientation angles of the source. While the orbital inclination angle is commonly reported in GW observations, the azimuthal one has been to date ignored. We show how the presence of more than one GW emission mode allows constraining this angle and, consequently, determines the kick direction in a real GW event. %We show that the higher-order mode content GW190412 enables the determination of both these angles and, consequently, the kick direction. We analyse the GW190412 signal, which contains higher-order modes, with a numerical-relativity surrogate waveform model for black-hole mergers. We find that while GW190412 is barely informative about the kick magnitude, we can constrain its direction. This forms angles $\theta_{KL}^{\text{-100M}}=28^{+23}_{-11}\,\deg$ with the orbital angular momentum defined at a reference time $t_{\rm ref}=-100\,M$ before merger (being preferentially kicked upwards), $\theta_{KN}=37^{+15}_{-12}\,\deg$ with the line-of-sight and $\phi_{KN}^{\text{-100M}}=46^{+32}_{-41}\,\deg$ with the projection of the latter onto the former, all at the $68\%$ credible level. We briefly discuss the potential application of this type of measurement for multi-messenger observations of black-hole mergers occurring in Active Galactic Nuclei. |
1307.5111 | Francesco Pannarale | Francesco Pannarale, Emanuele Berti, Koutarou Kyutoku, and Masaru
Shibata | Nonspinning black hole-neutron star mergers: a model for the amplitude
of gravitational waveforms | 22 pages; 10 figures; 4 tables; a MATHEMATICA package is available
at: http://www.phy.olemiss.edu/~berti/research.html | Physical Review D 88, 084011 (2013) | 10.1103/PhysRevD.88.084011 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Black hole-neutron star binary mergers display a much richer phenomenology
than black hole-black hole mergers, even in the relatively simple case -
considered in this paper - in which both the black hole and the neutron star
are nonspinning. When the neutron star is tidally disrupted, the gravitational
wave emission is radically different from the black hole-black hole case and it
can be broadly classified in two groups, depending on the spatial extent of the
disrupted material. We present a phenomenological model for the gravitational
waveform amplitude in the frequency domain that encompasses the three possible
outcomes of the merger: no tidal disruption, "mild", and "strong" tidal
disruption. The model is calibrated to general relativistic numerical
simulations using piecewise polytropic neutron star equations of state. It
should prove useful to extract information on the nuclear equation of state
from future gravitational-wave observations, and also to obtain more accurate
estimates of black hole-neutron star merger event rates in second- and
third-generation interferometric gravitational-wave detectors. We plan to
extend and improve the model as longer and more accurate gravitational
waveforms become available, and we will make it publicly available online as a
Mathematica package. We also present in appendix analytical fits of the
projected KAGRA noise spectral density, that should be useful in data analysis
applications.
| [
{
"created": "Fri, 19 Jul 2013 01:20:25 GMT",
"version": "v1"
},
{
"created": "Wed, 9 Oct 2013 17:47:05 GMT",
"version": "v2"
}
] | 2015-06-16 | [
[
"Pannarale",
"Francesco",
""
],
[
"Berti",
"Emanuele",
""
],
[
"Kyutoku",
"Koutarou",
""
],
[
"Shibata",
"Masaru",
""
]
] | Black hole-neutron star binary mergers display a much richer phenomenology than black hole-black hole mergers, even in the relatively simple case - considered in this paper - in which both the black hole and the neutron star are nonspinning. When the neutron star is tidally disrupted, the gravitational wave emission is radically different from the black hole-black hole case and it can be broadly classified in two groups, depending on the spatial extent of the disrupted material. We present a phenomenological model for the gravitational waveform amplitude in the frequency domain that encompasses the three possible outcomes of the merger: no tidal disruption, "mild", and "strong" tidal disruption. The model is calibrated to general relativistic numerical simulations using piecewise polytropic neutron star equations of state. It should prove useful to extract information on the nuclear equation of state from future gravitational-wave observations, and also to obtain more accurate estimates of black hole-neutron star merger event rates in second- and third-generation interferometric gravitational-wave detectors. We plan to extend and improve the model as longer and more accurate gravitational waveforms become available, and we will make it publicly available online as a Mathematica package. We also present in appendix analytical fits of the projected KAGRA noise spectral density, that should be useful in data analysis applications. |
1409.1902 | Rhiannon Cuttell | Rhiannon Cuttell and Mairi Sakellariadou | Fourth order deformed general relativity | fixed formatting, updated author name, 28 pages, 2 figures | Phys. Rev. D 90, 104026 (2014) | 10.1103/PhysRevD.90.104026 | KCL-PH-TH/2014-34 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Whenever the condition of anomaly freedom is imposed within the framework of
effective approaches to loop quantum cosmology, one seems to conclude that a
deformation of general covariance is required. Here, starting from a general
deformation we regain an effective gravitational Lagrangian including terms up
to fourth order in extrinsic curvature. We subsequently constrain the form of
the corrections, and then investigate the conditions for the occurrence of a
big bounce and the realisation of an inflationary era, in the presence of a
perfect fluid or scalar field.
| [
{
"created": "Fri, 5 Sep 2014 19:00:12 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Dec 2014 14:54:49 GMT",
"version": "v2"
},
{
"created": "Wed, 20 Jun 2018 15:21:41 GMT",
"version": "v3"
}
] | 2018-06-21 | [
[
"Cuttell",
"Rhiannon",
""
],
[
"Sakellariadou",
"Mairi",
""
]
] | Whenever the condition of anomaly freedom is imposed within the framework of effective approaches to loop quantum cosmology, one seems to conclude that a deformation of general covariance is required. Here, starting from a general deformation we regain an effective gravitational Lagrangian including terms up to fourth order in extrinsic curvature. We subsequently constrain the form of the corrections, and then investigate the conditions for the occurrence of a big bounce and the realisation of an inflationary era, in the presence of a perfect fluid or scalar field. |
gr-qc/0507128 | Filimonova Irina V | Yu.F.Pirogov | Space-time: emerging vs. existing | Plenary talk presented at Workshop on High Energy Physics&Field
Theory (Protvino, Russia, 2004) | null | null | HEPFT/2004/9 | gr-qc | null | The concept of the space-time as emerging in the world phase transition, vs.
a priori existing, is put forward. The theory of gravity with two basic
symmetries, the global affine one and the general covariance, is developed.
Implications for the Universe are indicated.
| [
{
"created": "Fri, 29 Jul 2005 07:09:48 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Pirogov",
"Yu. F.",
""
]
] | The concept of the space-time as emerging in the world phase transition, vs. a priori existing, is put forward. The theory of gravity with two basic symmetries, the global affine one and the general covariance, is developed. Implications for the Universe are indicated. |
2106.06968 | Eric Poisson | Michael LaHaye and Eric Poisson | Particle hanging on a string near a Schwarzschild black hole | 43 pages, no figure, matches version published in Physical Review D | Phys. Rev. D 104, 044016 (2021) | 10.1103/PhysRevD.104.044016 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The literature features many instances of spacetimes containing two black
holes held apart by a thin distribution of matter on the axis joining the
holes. For all such spacetimes, the Einstein field equations are integrated
with an energy-momentum tensor that does not include a contribution from the
axial matter; the presence of this matter is inferred instead from the
existence of a conical singularity in the spacetime. And for all such
spacetimes, the axial matter is characterized by a pressure (or tension) equal
to its linear energy density; the matter is therefore revealed to have a very
specific equation of state. Our purpose with this paper is to show that the
axial matter can be introduced at the very start of the exercise, through the
specification of a distributional energy-momentum tensor, and that one can
choose for it any equation of state. To evade no-go theorems regarding line
sources in general relativity, we retreat to a perturbative expansion of the
gravitational field, using the Schwarzschild metric as a description of the
background spacetime. Instead of a second black hole, our prototypical system
features a point particle at a fixed position outside the Schwarzschild black
hole, attached to a string extending to infinity. This matter is described in
terms of a distributional energy-momentum tensor, and we examine different
equations of state for the string. To integrate the field equations we
introduce a new "Weyl" gauge for the metric perturbation, which allows us to
find closed-form expressions for the gravitational potentials. Our solutions
are linearized versions of multi-hole spacetimes, and some of them feature
strings with a varying tension, unequal to the energy density. We describe the
properties of these spacetimes, and begin an exploration of their extended
thermodynamics.
| [
{
"created": "Sun, 13 Jun 2021 11:43:40 GMT",
"version": "v1"
},
{
"created": "Mon, 16 Aug 2021 19:56:24 GMT",
"version": "v2"
}
] | 2021-08-18 | [
[
"LaHaye",
"Michael",
""
],
[
"Poisson",
"Eric",
""
]
] | The literature features many instances of spacetimes containing two black holes held apart by a thin distribution of matter on the axis joining the holes. For all such spacetimes, the Einstein field equations are integrated with an energy-momentum tensor that does not include a contribution from the axial matter; the presence of this matter is inferred instead from the existence of a conical singularity in the spacetime. And for all such spacetimes, the axial matter is characterized by a pressure (or tension) equal to its linear energy density; the matter is therefore revealed to have a very specific equation of state. Our purpose with this paper is to show that the axial matter can be introduced at the very start of the exercise, through the specification of a distributional energy-momentum tensor, and that one can choose for it any equation of state. To evade no-go theorems regarding line sources in general relativity, we retreat to a perturbative expansion of the gravitational field, using the Schwarzschild metric as a description of the background spacetime. Instead of a second black hole, our prototypical system features a point particle at a fixed position outside the Schwarzschild black hole, attached to a string extending to infinity. This matter is described in terms of a distributional energy-momentum tensor, and we examine different equations of state for the string. To integrate the field equations we introduce a new "Weyl" gauge for the metric perturbation, which allows us to find closed-form expressions for the gravitational potentials. Our solutions are linearized versions of multi-hole spacetimes, and some of them feature strings with a varying tension, unequal to the energy density. We describe the properties of these spacetimes, and begin an exploration of their extended thermodynamics. |
2009.06990 | F Shojai | R. Saadati, F. Shojai | Regular Kiselev black hole with a de Sitter core | 21 pages, 8 figures | Class. Quantum Grav. 38 (2021) 135025 | 10.1088/1361-6382/abfed5 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present some new aspects of Kiselev black hole and then study the null and
timelike thin shell collapse in this spacetime. For the latter, we show that
Kiselev black hole can be matched to de Sitter core with a thin timelike dust
shell to produce a non-singular black hole space-time. It is argued that for
timelike hypersurface, the equation of state parameter must be non-negative.
Using Barrabes-Israel junction conditions, the equation of motion of the shell
is obtained. The stability of stationary solutions of the shell is discussed
and some appropriate ranges for the parameters of shell and Kiselev geometry
are found for which a stable stationary black hole is constructed.
| [
{
"created": "Tue, 15 Sep 2020 11:24:38 GMT",
"version": "v1"
},
{
"created": "Fri, 25 Dec 2020 10:01:29 GMT",
"version": "v2"
},
{
"created": "Tue, 4 May 2021 14:14:28 GMT",
"version": "v3"
}
] | 2021-06-10 | [
[
"Saadati",
"R.",
""
],
[
"Shojai",
"F.",
""
]
] | We present some new aspects of Kiselev black hole and then study the null and timelike thin shell collapse in this spacetime. For the latter, we show that Kiselev black hole can be matched to de Sitter core with a thin timelike dust shell to produce a non-singular black hole space-time. It is argued that for timelike hypersurface, the equation of state parameter must be non-negative. Using Barrabes-Israel junction conditions, the equation of motion of the shell is obtained. The stability of stationary solutions of the shell is discussed and some appropriate ranges for the parameters of shell and Kiselev geometry are found for which a stable stationary black hole is constructed. |
0712.1515 | Steven Hergt | Steven Hergt, Gerhard Sch\"afer | Higher-order-in-spin interaction Hamiltonians for binary black holes
from source terms of Kerr geometry in approximate ADM coordinates | REVTeX4, 20 pages, typos corrected in Eq. (124) and (130) | Phys.Rev.D77:104001,2008 | 10.1103/PhysRevD.77.104001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Kerr metric outside the ergosphere is transformed into ADM coordinates up
to the orders $1/r^4$ and $a^2$, respectively in radial coordinate $r$ and
reduced angular momentum variable $a$, starting from the Kerr solution in
quasi-isotropic as well as harmonic coordinates. The distributional source
terms for the approximate solution are calculated. To leading order in linear
momenta, higher-order-in-spin interaction Hamiltonians for black-hole binaries
are derived.
| [
{
"created": "Mon, 10 Dec 2007 15:46:03 GMT",
"version": "v1"
},
{
"created": "Thu, 13 Mar 2008 11:34:46 GMT",
"version": "v2"
},
{
"created": "Mon, 5 May 2008 15:06:45 GMT",
"version": "v3"
},
{
"created": "Wed, 25 Apr 2012 09:41:34 GMT",
"version": "v4"
}
] | 2012-04-26 | [
[
"Hergt",
"Steven",
""
],
[
"Schäfer",
"Gerhard",
""
]
] | The Kerr metric outside the ergosphere is transformed into ADM coordinates up to the orders $1/r^4$ and $a^2$, respectively in radial coordinate $r$ and reduced angular momentum variable $a$, starting from the Kerr solution in quasi-isotropic as well as harmonic coordinates. The distributional source terms for the approximate solution are calculated. To leading order in linear momenta, higher-order-in-spin interaction Hamiltonians for black-hole binaries are derived. |
gr-qc/0502065 | Emanuele Berti | Emanuele Berti, Kostas D. Kokkotas | Quasinormal modes of Kerr-Newman black holes: coupling of
electromagnetic and gravitational perturbations | 13 pages, 3 figures. Minor changes to match version accepted in Phys.
Rev. D | Phys.Rev. D71 (2005) 124008 | 10.1103/PhysRevD.71.124008 | null | gr-qc astro-ph hep-th | null | We compute numerically the quasinormal modes of Kerr-Newman black holes in
the scalar case, for which the perturbation equations are separable. Then we
study different approximations to decouple electromagnetic and gravitational
perturbations of the Kerr-Newman metric, computing the corresponding
quasinormal modes. Our results suggest that the Teukolsky-like equation derived
by Dudley and Finley gives a good approximation to the dynamics of a rotating
charged black hole for Q<M/2. Though insufficient to deal with Kerr-Newman
based models of elementary particles, the Dudley-Finley equation should be
adequate for astrophysical applications.
| [
{
"created": "Mon, 14 Feb 2005 17:05:46 GMT",
"version": "v1"
},
{
"created": "Sun, 29 May 2005 20:59:44 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Berti",
"Emanuele",
""
],
[
"Kokkotas",
"Kostas D.",
""
]
] | We compute numerically the quasinormal modes of Kerr-Newman black holes in the scalar case, for which the perturbation equations are separable. Then we study different approximations to decouple electromagnetic and gravitational perturbations of the Kerr-Newman metric, computing the corresponding quasinormal modes. Our results suggest that the Teukolsky-like equation derived by Dudley and Finley gives a good approximation to the dynamics of a rotating charged black hole for Q<M/2. Though insufficient to deal with Kerr-Newman based models of elementary particles, the Dudley-Finley equation should be adequate for astrophysical applications. |
gr-qc/9911009 | Jorge Pullin | Cayetano Di Bartolo, Rodolfo Gambini, Jorge Griego, Jorge Pullin | Canonical quantum gravity in the Vassiliev invariants arena: I.
Kinematical structure | 21 Pages, RevTex, many figures included with psfig | Class.Quant.Grav. 17 (2000) 3211-3238 | 10.1088/0264-9381/17/16/309 | CGPG-99/11-1 | gr-qc hep-th | null | We generalize the idea of Vassiliev invariants to the spin network context,
with the aim of using these invariants as a kinematical arena for a canonical
quantization of gravity. This paper presents a detailed construction of these
invariants (both ambient and regular isotopic) requiring a significant
elaboration based on the use of Chern-Simons perturbation theory which extends
the work of Kauffman, Martin and Witten to four-valent networks. We show that
this space of knot invariants has the crucial property -from the point of view
of the quantization of gravity- of being loop differentiable in the sense of
distributions. This allows the definition of diffeomorphism and Hamiltonian
constraints. We show that the invariants are annihilated by the diffeomorphism
constraint. In a companion paper we elaborate on the definition of a
Hamiltonian constraint, discuss the constraint algebra, and show that the
construction leads to a consistent theory of canonical quantum gravity.
| [
{
"created": "Wed, 3 Nov 1999 09:04:02 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Di Bartolo",
"Cayetano",
""
],
[
"Gambini",
"Rodolfo",
""
],
[
"Griego",
"Jorge",
""
],
[
"Pullin",
"Jorge",
""
]
] | We generalize the idea of Vassiliev invariants to the spin network context, with the aim of using these invariants as a kinematical arena for a canonical quantization of gravity. This paper presents a detailed construction of these invariants (both ambient and regular isotopic) requiring a significant elaboration based on the use of Chern-Simons perturbation theory which extends the work of Kauffman, Martin and Witten to four-valent networks. We show that this space of knot invariants has the crucial property -from the point of view of the quantization of gravity- of being loop differentiable in the sense of distributions. This allows the definition of diffeomorphism and Hamiltonian constraints. We show that the invariants are annihilated by the diffeomorphism constraint. In a companion paper we elaborate on the definition of a Hamiltonian constraint, discuss the constraint algebra, and show that the construction leads to a consistent theory of canonical quantum gravity. |
1905.11919 | Daniel Blixt | Daniel Blixt, Manuel Hohmann, Martin Kr\v{s}\v{s}\'ak and Christian
Pfeifer | Hamiltonian Analysis In New General Relativity | 6 pages, 1 figure, talk delivered at the AT1 parallel session,
"Hamiltonian Analysis In New General Relativity", at the 15th Marcel
Grossmann Meeting 2018. Corrections of great importance have been
implemented, which lead to changes in Fig. 1 | null | 10.1142/9789811258251_0038 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is known that one can formulate an action in teleparallel gravity which is
equivalent to general relativity, up to a boundary term. In this geometry we
have vanishing curvature, and non-vanishing torsion. The action is constructed
by three different contractions of torsion with specific coefficients. By
allowing these coefficients to be arbitrary we get the theory which is called
`new general relativity'. In this note, the Lagrangian for new general
relativity is written down in ADM-variables. In order to write down the
Hamiltonian we need to invert the velocities to canonical variables. However,
the inversion depends on the specific combination of constraints satisfied by
the theory (which depends on the coefficients in the Lagrangian). It is found
that one can combine these constraints in 9 different ways to obtain
non-trivial theories, each with a different inversion formula.
| [
{
"created": "Tue, 28 May 2019 16:30:11 GMT",
"version": "v1"
},
{
"created": "Fri, 26 Nov 2021 14:06:50 GMT",
"version": "v2"
}
] | 2022-07-07 | [
[
"Blixt",
"Daniel",
""
],
[
"Hohmann",
"Manuel",
""
],
[
"Krššák",
"Martin",
""
],
[
"Pfeifer",
"Christian",
""
]
] | It is known that one can formulate an action in teleparallel gravity which is equivalent to general relativity, up to a boundary term. In this geometry we have vanishing curvature, and non-vanishing torsion. The action is constructed by three different contractions of torsion with specific coefficients. By allowing these coefficients to be arbitrary we get the theory which is called `new general relativity'. In this note, the Lagrangian for new general relativity is written down in ADM-variables. In order to write down the Hamiltonian we need to invert the velocities to canonical variables. However, the inversion depends on the specific combination of constraints satisfied by the theory (which depends on the coefficients in the Lagrangian). It is found that one can combine these constraints in 9 different ways to obtain non-trivial theories, each with a different inversion formula. |
1911.05278 | Jieci Wang | Jieci Wang, Cuihong Wen, Songbai Chen, and Jilliang Jing | Generation of genuine tripartite entanglement for continuous variables
in de Sitter space | 17pages, 7 figures | Phys. Lett. B 800, 135109 (2020) | 10.1016/j.physletb.2019.135109 | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the distribution of quantum entanglement for continuous variables
among causally disconnected open charts in de Sitter space. It is found that
genuine tripartite entanglement is generated among the open chart modes under
the influence of curvature of de Sitter space for any nonzero squeezing.
Bipartite entanglement is also generated when the curvature is strong enough,
even though the observers are separated by the event horizon. This provides a
clearcut interpretation of the two-mode squeezing mechanism in the de Sitter
space. In addition, the curvature generated genuine tripartite entanglement is
found to be less sensitive to the mass parameter than the generated bipartite
entanglement. The effects of the curvature of de Sitter space on the generated
entanglement become more apparent in the limit of conformal and massless scalar
fields.
| [
{
"created": "Wed, 13 Nov 2019 04:00:45 GMT",
"version": "v1"
}
] | 2020-01-23 | [
[
"Wang",
"Jieci",
""
],
[
"Wen",
"Cuihong",
""
],
[
"Chen",
"Songbai",
""
],
[
"Jing",
"Jilliang",
""
]
] | We study the distribution of quantum entanglement for continuous variables among causally disconnected open charts in de Sitter space. It is found that genuine tripartite entanglement is generated among the open chart modes under the influence of curvature of de Sitter space for any nonzero squeezing. Bipartite entanglement is also generated when the curvature is strong enough, even though the observers are separated by the event horizon. This provides a clearcut interpretation of the two-mode squeezing mechanism in the de Sitter space. In addition, the curvature generated genuine tripartite entanglement is found to be less sensitive to the mass parameter than the generated bipartite entanglement. The effects of the curvature of de Sitter space on the generated entanglement become more apparent in the limit of conformal and massless scalar fields. |
0811.1781 | Roman Buniy | Roman V. Buniy and Thomas W. Kephart | Decomposition of geometric perturbations | 7 pages | Phys.Lett.B674:313-315,2009 | 10.1016/j.physletb.2009.03.043 | IUHET-522 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | For an infinitesimal deformation of a Riemannian manifold, we prove that the
scalar, vector, and tensor modes in decompositions of perturbations of the
metric tensor, the scalar curvature, the Ricci tensor, and the Einstein tensor
decouple if and only if the manifold is Einstein. Four-dimensional space-time
satisfying the condition of the theorem is homogeneous and isotropic.
Cosmological applications are discussed.
| [
{
"created": "Wed, 12 Nov 2008 20:57:05 GMT",
"version": "v1"
}
] | 2009-11-13 | [
[
"Buniy",
"Roman V.",
""
],
[
"Kephart",
"Thomas W.",
""
]
] | For an infinitesimal deformation of a Riemannian manifold, we prove that the scalar, vector, and tensor modes in decompositions of perturbations of the metric tensor, the scalar curvature, the Ricci tensor, and the Einstein tensor decouple if and only if the manifold is Einstein. Four-dimensional space-time satisfying the condition of the theorem is homogeneous and isotropic. Cosmological applications are discussed. |
1608.03830 | Mauricio Bellini | Jes\'us Mart\'in Romero (IFIMAR - CONICET and UNMdP), Mauricio Bellini
(IFIMAR - CONICET and UNMdP) | Gravito-magnetic monopoles in traversable wormholes from WIMT | Version accepted in Phys. Dark Univ | null | null | null | gr-qc hep-th physics.space-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using Weitzenb\"ock Induced Matter Theory (WIMT), we study Schwarzschild
wormholes performing different foliations on an extended (non-vaccuum) 5D
manifold. We explore the geodesic equations for observers which are in the
interior of a traversable wormhole and how these observers can detect
gravito-magnetic monopoles which are dual to gravito-electric sources observed
in the outer zone of some Schwarzschild Black-Hole (BH). The densities of these
monopoles are calculated and quantized in the Dirac sense. This kind of duality
on the extended Einstein-Maxwell equations, relates electric and magnetic
charges on causally disconnected space regions.
| [
{
"created": "Fri, 12 Aug 2016 15:35:10 GMT",
"version": "v1"
},
{
"created": "Sun, 11 Dec 2016 13:53:06 GMT",
"version": "v2"
}
] | 2016-12-13 | [
[
"Romero",
"Jesús Martín",
"",
"IFIMAR - CONICET and UNMdP"
],
[
"Bellini",
"Mauricio",
"",
"IFIMAR - CONICET and UNMdP"
]
] | Using Weitzenb\"ock Induced Matter Theory (WIMT), we study Schwarzschild wormholes performing different foliations on an extended (non-vaccuum) 5D manifold. We explore the geodesic equations for observers which are in the interior of a traversable wormhole and how these observers can detect gravito-magnetic monopoles which are dual to gravito-electric sources observed in the outer zone of some Schwarzschild Black-Hole (BH). The densities of these monopoles are calculated and quantized in the Dirac sense. This kind of duality on the extended Einstein-Maxwell equations, relates electric and magnetic charges on causally disconnected space regions. |
0807.1710 | Mew-Bing Wan | M.-B. Wan, K.-J. Jin, W.-M. Suen | Dynamical Analysis of the Structure of Neutron Star Critical Collapses | Poster version presented at the "2nd Course of the International
School on Astrophysical Relativity", Erice, Italy, June 27th - July 5th;
Shorter version to appear in Proceedings | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Jin et al reported that axisymmetric simulations of NS-like objects with
polytropic EOS undergo critical gravitational collapse. As the critical
collapse observed via fine-tuning of the adiabatic index $\Gamma$, they
conjecture that critical phenomena may occur in realistic astrophysical
scenarios. To clarify the implications this numerical observation has on
realistic astrophysical scenarios, here, we perform dynamical analysis on the
structure of the critical collapse observed in the former work. We report the
time scales and oscillation frequencies exhibited by the critical solution and
compare these results with values obtained from analytic perturbative mode
analysis of equilibrium TOV configurations. We also establish the universality
of the critical solution with respect to a 1-parameter family of initial data
as well as the phase space manifold of the critical collapse.
| [
{
"created": "Thu, 10 Jul 2008 17:40:11 GMT",
"version": "v1"
},
{
"created": "Thu, 10 Jul 2008 22:57:22 GMT",
"version": "v2"
}
] | 2008-07-11 | [
[
"Wan",
"M. -B.",
""
],
[
"Jin",
"K. -J.",
""
],
[
"Suen",
"W. -M.",
""
]
] | Jin et al reported that axisymmetric simulations of NS-like objects with polytropic EOS undergo critical gravitational collapse. As the critical collapse observed via fine-tuning of the adiabatic index $\Gamma$, they conjecture that critical phenomena may occur in realistic astrophysical scenarios. To clarify the implications this numerical observation has on realistic astrophysical scenarios, here, we perform dynamical analysis on the structure of the critical collapse observed in the former work. We report the time scales and oscillation frequencies exhibited by the critical solution and compare these results with values obtained from analytic perturbative mode analysis of equilibrium TOV configurations. We also establish the universality of the critical solution with respect to a 1-parameter family of initial data as well as the phase space manifold of the critical collapse. |
2302.10966 | Nuno Barros e S\'a | Nuno Barros e S\'a | Dirac bracket and time dependent constraints | 11 pages, 1 figure | null | null | null | gr-qc math-ph math.MP quant-ph | http://creativecommons.org/licenses/by/4.0/ | We provide a compact derivation of the Dirac bracket and of the equations of
motion for second class constrained systems when the constraints are time
dependent. The examples of Parameterized Mechanics and of General Relativity
after gauge fixing are given, and the need for the use of time dependent gauge
fixing conditions in these examples is illustrated geometrically.
| [
{
"created": "Tue, 21 Feb 2023 19:50:09 GMT",
"version": "v1"
}
] | 2023-02-23 | [
[
"Sá",
"Nuno Barros e",
""
]
] | We provide a compact derivation of the Dirac bracket and of the equations of motion for second class constrained systems when the constraints are time dependent. The examples of Parameterized Mechanics and of General Relativity after gauge fixing are given, and the need for the use of time dependent gauge fixing conditions in these examples is illustrated geometrically. |
2309.15752 | Eleftherios-Ermis Tselentis | Eleftherios-Ermis Tselentis, \"Amin Baumeler | The M\"obius game and other Bell tests for relativity | Comments welcome! | null | null | null | gr-qc quant-ph | http://creativecommons.org/licenses/by/4.0/ | We derive multiparty games that, if the winning chance exceeds a certain
limit, prove the incompatibility of the parties' causal relations with any
partial order. This, in turn, means that the parties exert a back-action on the
causal relations; the causal relations are dynamical. The games turn out to be
representable by directed graphs, for instance by an orientation of the
M\"obius ladder. We discuss these games as device-independent tests of
spacetime's dynamical nature in general relativity. To do so, we design a
relativistic setting where, in the Minkowski spacetime, the winning chance is
bound to the limits. In contrast, we find otherwise tame processes with
classical control of causal order that win the games deterministically. These
suggest a violation of the bounds in gravitational implementations. We obtain
these games by uncovering a "pairwise central symmetry" of the correlations in
question. This symmetry allows us to recycle the facets of the acyclic subgraph
polytope studied by Gr\"otschel, J\"unger, and Reinelt in the mid-80s for
combinatorial optimization. In addition, we derive multiparty games in a
scenario where the polytope dimension grows only linearly in the number of
parties. Here, exceeding the limits not only proves the dynamical nature of the
causal relations, but also that the correlations are incompatible with any
global causal order.
| [
{
"created": "Wed, 27 Sep 2023 16:08:13 GMT",
"version": "v1"
}
] | 2023-09-28 | [
[
"Tselentis",
"Eleftherios-Ermis",
""
],
[
"Baumeler",
"Ämin",
""
]
] | We derive multiparty games that, if the winning chance exceeds a certain limit, prove the incompatibility of the parties' causal relations with any partial order. This, in turn, means that the parties exert a back-action on the causal relations; the causal relations are dynamical. The games turn out to be representable by directed graphs, for instance by an orientation of the M\"obius ladder. We discuss these games as device-independent tests of spacetime's dynamical nature in general relativity. To do so, we design a relativistic setting where, in the Minkowski spacetime, the winning chance is bound to the limits. In contrast, we find otherwise tame processes with classical control of causal order that win the games deterministically. These suggest a violation of the bounds in gravitational implementations. We obtain these games by uncovering a "pairwise central symmetry" of the correlations in question. This symmetry allows us to recycle the facets of the acyclic subgraph polytope studied by Gr\"otschel, J\"unger, and Reinelt in the mid-80s for combinatorial optimization. In addition, we derive multiparty games in a scenario where the polytope dimension grows only linearly in the number of parties. Here, exceeding the limits not only proves the dynamical nature of the causal relations, but also that the correlations are incompatible with any global causal order. |
gr-qc/0703011 | Alikram Aliev | A. N. Aliev, H. Cebeci, T. Dereli | Exact Solutions in Five-Dimensional Axi-dilaton Gravity with
Euler-Poincare Term | New formulas and references added | Class.Quant.Grav.24:3425-3436,2007 | 10.1088/0264-9381/24/13/017 | null | gr-qc hep-th | null | We examine the effective field equations that are obtained from the
axi-dilaton gravity action with a second order Euler-Poincare term and a
cosmological constant in all higher dimensions. We solve these equations for
five-dimensional spacetimes possessing homogeneity and isotropy in their
three-dimensional subspaces. For a number of interesting special cases we show
that the solutions fall into two main classes: The first class consists of
time-dependent solutions with spherical or hyperboloidal symmetry which require
certain fine-tuning relations between the coupling constants of the model and
the cosmological constant. Solutions in the second class are locally static and
prove the validity of Birkhoff's staticity theorem in the axi-dilaton gravity.
We also give a special class of static solutions, among them the well-known
black hole solutions in which the usual electric charge is superseded by an
axion charge.
| [
{
"created": "Fri, 2 Mar 2007 10:06:30 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Jun 2007 06:32:15 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Aliev",
"A. N.",
""
],
[
"Cebeci",
"H.",
""
],
[
"Dereli",
"T.",
""
]
] | We examine the effective field equations that are obtained from the axi-dilaton gravity action with a second order Euler-Poincare term and a cosmological constant in all higher dimensions. We solve these equations for five-dimensional spacetimes possessing homogeneity and isotropy in their three-dimensional subspaces. For a number of interesting special cases we show that the solutions fall into two main classes: The first class consists of time-dependent solutions with spherical or hyperboloidal symmetry which require certain fine-tuning relations between the coupling constants of the model and the cosmological constant. Solutions in the second class are locally static and prove the validity of Birkhoff's staticity theorem in the axi-dilaton gravity. We also give a special class of static solutions, among them the well-known black hole solutions in which the usual electric charge is superseded by an axion charge. |
1510.01953 | Sumanta Chakraborty | Sumanta Chakraborty and Soumitra SenGupta | Spherically symmetric brane in a bulk of f(R) and Gauss-Bonnet Gravity | revised, 35 Pages, 3 figures | Class. Quant. Grav. 33 225001 (2016) | 10.1088/0264-9381/33/22/225001 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Effective gravitational field equations on a four dimensional brane embedded
in a five dimensional bulk have been considered. Using the Einstein-Hilbert
action along with the Gauss-Bonnet correction term, we have derived static
spherically symmetric vacuum solution to the effective field equations, first
order in the Gauss-Bonnet coupling parameter. The solution so obtained, has one
part corresponding to general relativity with an additional correction term,
proportional to the Gauss-Bonnet coupling parameter. The correction term
modifies the spacetime structure, in particular, the location of the event
horizon. Proceeding further, we have derived effective field equations for
$f(R)$ gravity with Gauss-Bonnet correction term and a static spherically
symmetric solution has been obtained. In this case the Gauss-Bonnet term
modifies both the event and cosmological horizon of the spacetime. There exist
another way of obtaining the brane metric --- expanding the bulk gravitational
field equations in the ratio of bulk to brane curvature scale and assuming a
separable bulk metric ansatz. It turns out that static, spherically symmetric
solutions obtained from this perturbative method can be matched exactly, with
the solutions derived earlier. This will hold for Einstein-Hilbert plus
Gauss-Bonnet as well as for f(R) with the Gauss-Bonnet correction. Implications
of these results are discussed.
| [
{
"created": "Tue, 6 Oct 2015 05:52:11 GMT",
"version": "v1"
},
{
"created": "Thu, 20 Oct 2016 01:04:17 GMT",
"version": "v2"
}
] | 2016-10-21 | [
[
"Chakraborty",
"Sumanta",
""
],
[
"SenGupta",
"Soumitra",
""
]
] | Effective gravitational field equations on a four dimensional brane embedded in a five dimensional bulk have been considered. Using the Einstein-Hilbert action along with the Gauss-Bonnet correction term, we have derived static spherically symmetric vacuum solution to the effective field equations, first order in the Gauss-Bonnet coupling parameter. The solution so obtained, has one part corresponding to general relativity with an additional correction term, proportional to the Gauss-Bonnet coupling parameter. The correction term modifies the spacetime structure, in particular, the location of the event horizon. Proceeding further, we have derived effective field equations for $f(R)$ gravity with Gauss-Bonnet correction term and a static spherically symmetric solution has been obtained. In this case the Gauss-Bonnet term modifies both the event and cosmological horizon of the spacetime. There exist another way of obtaining the brane metric --- expanding the bulk gravitational field equations in the ratio of bulk to brane curvature scale and assuming a separable bulk metric ansatz. It turns out that static, spherically symmetric solutions obtained from this perturbative method can be matched exactly, with the solutions derived earlier. This will hold for Einstein-Hilbert plus Gauss-Bonnet as well as for f(R) with the Gauss-Bonnet correction. Implications of these results are discussed. |
gr-qc/0408099 | Vitor Cardoso | Emanuele Berti, Vitor Cardoso, Jose' P. S. Lemos | Quasinormal modes and classical wave propagation in analogue black holes | 19 pages, 12 figures, ReVTeX4; v2: minor modifications and
corrections | Phys.Rev. D70 (2004) 124006 | 10.1103/PhysRevD.70.124006 | null | gr-qc astro-ph hep-ph hep-th physics.flu-dyn | null | Many properties of black holes can be studied using acoustic analogues in the
laboratory through the propagation of sound waves. We investigate in detail
sound wave propagation in a rotating acoustic (2+1)-dimensional black hole,
which corresponds to the ``draining bathtub'' fluid flow. We compute the
quasinormal mode frequencies of this system and discuss late-time power-law
tails. Due to the presence of an ergoregion, waves in a rotating acoustic black
hole can be superradiantly amplified. We compute superradiant reflection
coefficients and instability timescales for the acoustic black hole bomb, the
equivalent of the Press-Teukolsky black hole bomb. Finally we discuss
quasinormal modes and late-time tails in a non-rotating canonical acoustic
black hole, corresponding to an incompressible, spherically symmetric
(3+1)-dimensional fluid flow.
| [
{
"created": "Tue, 31 Aug 2004 08:19:02 GMT",
"version": "v1"
},
{
"created": "Sat, 20 Nov 2004 14:22:52 GMT",
"version": "v2"
}
] | 2016-08-31 | [
[
"Berti",
"Emanuele",
""
],
[
"Cardoso",
"Vitor",
""
],
[
"Lemos",
"Jose' P. S.",
""
]
] | Many properties of black holes can be studied using acoustic analogues in the laboratory through the propagation of sound waves. We investigate in detail sound wave propagation in a rotating acoustic (2+1)-dimensional black hole, which corresponds to the ``draining bathtub'' fluid flow. We compute the quasinormal mode frequencies of this system and discuss late-time power-law tails. Due to the presence of an ergoregion, waves in a rotating acoustic black hole can be superradiantly amplified. We compute superradiant reflection coefficients and instability timescales for the acoustic black hole bomb, the equivalent of the Press-Teukolsky black hole bomb. Finally we discuss quasinormal modes and late-time tails in a non-rotating canonical acoustic black hole, corresponding to an incompressible, spherically symmetric (3+1)-dimensional fluid flow. |
2204.07864 | Ali \"Ovg\"un Dr. | Wajiha Javed, Muhammad Aqib and Ali \"Ovg\"un | Effect of the magnetic charge on weak deflection angle and greybody
bound of the black hole in Einstein-Gauss-Bonnet gravity | 11 pages. Accepted for publication in Physics Letters B
(https://www.sciencedirect.com/science/article/pii/S0370269322002489) | Physics Letters B 829, 137114 (2022) | 10.1016/j.physletb.2022.137114 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The objective of this paper is to analyze the weak deflection angle of
Einstein-Gauss-Bonnet gravity in the presence of plasma medium. To attain our
results, we implement the Gibbons and Werner approach and use the Gauss-Bonnet
theorem to Einstein gravity to acquire the resulting deflection angle of
photon's ray in the weak field limit. Moreover, we illustrate the behavior of
plasma medium and non-plasma mediums on the deflection of photon's ray in the
framework of Einstein-Gauss-Bonnet gravity. Similarly, we observe the graphical
influences of deflection angle on Einstein-Gauss-Bonnet gravity with the
consideration of both plasma and non-plasma mediums. Later, we observe the
rigorous bounds phenomenon of the greybody factor in contact with
Einstein-Gauss-Bonnet gravity and calculate the outcomes, analyze graphically
for specific values of parameters.
| [
{
"created": "Sat, 16 Apr 2022 20:12:38 GMT",
"version": "v1"
}
] | 2022-04-28 | [
[
"Javed",
"Wajiha",
""
],
[
"Aqib",
"Muhammad",
""
],
[
"Övgün",
"Ali",
""
]
] | The objective of this paper is to analyze the weak deflection angle of Einstein-Gauss-Bonnet gravity in the presence of plasma medium. To attain our results, we implement the Gibbons and Werner approach and use the Gauss-Bonnet theorem to Einstein gravity to acquire the resulting deflection angle of photon's ray in the weak field limit. Moreover, we illustrate the behavior of plasma medium and non-plasma mediums on the deflection of photon's ray in the framework of Einstein-Gauss-Bonnet gravity. Similarly, we observe the graphical influences of deflection angle on Einstein-Gauss-Bonnet gravity with the consideration of both plasma and non-plasma mediums. Later, we observe the rigorous bounds phenomenon of the greybody factor in contact with Einstein-Gauss-Bonnet gravity and calculate the outcomes, analyze graphically for specific values of parameters. |
gr-qc/0303103 | Gilberto Medeiros Kremer | G. M. Kremer | Irreversible Processes in a Universe modelled as a mixture of a
Chaplygin gas and radiation | 8 pages, 1 figure, to be published in GRG | Gen.Rel.Grav. 35 (2003) 1459-1466 | 10.1023/A:1024586719004 | null | gr-qc | null | The evolution of a Universe modelled as a mixture of a Chaplygin gas and
radiation is determined by taking into account irreversible processes. This
mixture could interpolate periods of a radiation dominated, a matter dominated
and a cosmological constant dominated Universe. The results of a Universe
modelled by this mixture are compared with the results of a mixture whose
constituents are radiation and quintessence. Among other results it is shown
that: (a) for both models there exists a period of a past deceleration with a
present acceleration; (b) the slope of the acceleration of the Universe
modelled as a mixture of a Chaplygin gas with radiation is more pronounced than
that modelled as a mixture of quintessence and radiation; (c) the energy
density of the Chaplygin gas tends to a constant value at earlier times than
the energy density of quintessence does; (d) the energy density of radiation
for both mixtures coincide and decay more rapidly than the energy densities of
the Chaplygin gas and of quintessence.
| [
{
"created": "Wed, 26 Mar 2003 11:18:36 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Kremer",
"G. M.",
""
]
] | The evolution of a Universe modelled as a mixture of a Chaplygin gas and radiation is determined by taking into account irreversible processes. This mixture could interpolate periods of a radiation dominated, a matter dominated and a cosmological constant dominated Universe. The results of a Universe modelled by this mixture are compared with the results of a mixture whose constituents are radiation and quintessence. Among other results it is shown that: (a) for both models there exists a period of a past deceleration with a present acceleration; (b) the slope of the acceleration of the Universe modelled as a mixture of a Chaplygin gas with radiation is more pronounced than that modelled as a mixture of quintessence and radiation; (c) the energy density of the Chaplygin gas tends to a constant value at earlier times than the energy density of quintessence does; (d) the energy density of radiation for both mixtures coincide and decay more rapidly than the energy densities of the Chaplygin gas and of quintessence. |
1411.4854 | Amir M. Abbassi | Habib Abedi and Amir M. Abbassi | Gravitational constant in multiple field gravity | 13 pages,no fig., JCAP style | null | 10.1088/1475-7516/2015/05/026 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the present study, we consider general form of the Lagrangian $ f(R,
\phi^{I}, X) $, that is a function of the Ricci scalar, multiple scalar fields
and non-canonical kinetic terms. We obtain the effective Newton's constant deep
inside the Hubble radius. We use Jordan and Einstein frames, and study the
conservation of energy-momentum tensor.
| [
{
"created": "Tue, 18 Nov 2014 14:48:08 GMT",
"version": "v1"
}
] | 2015-05-27 | [
[
"Abedi",
"Habib",
""
],
[
"Abbassi",
"Amir M.",
""
]
] | In the present study, we consider general form of the Lagrangian $ f(R, \phi^{I}, X) $, that is a function of the Ricci scalar, multiple scalar fields and non-canonical kinetic terms. We obtain the effective Newton's constant deep inside the Hubble radius. We use Jordan and Einstein frames, and study the conservation of energy-momentum tensor. |
1707.09814 | Donato Bini | Donato Bini, Andrea Geralico, Justin Vines | Hyperbolic scattering of spinning particles by a Kerr black hole | 12 pages, 3 figures, revtex macros | Phys. Rev. D 96, 084044 (2017) | 10.1103/PhysRevD.96.084044 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the scattering of a spinning test particle by a Kerr black
hole within the Mathisson-Papapetrou-Dixon model to linear order in spin. The
particle's spin and orbital angular momentum are taken to be aligned with the
black hole's spin. Both the particle's mass and spin length are assumed to be
small in comparison with the characteristic length scale of the background
curvature, in order to avoid backreaction effects. We analytically compute the
modifications due to the particle's spin to the scattering angle, the
periastron shift, and the condition for capture by the black hole, extending
previous results valid for the nonrotating Schwarzschild background. Finally,
we discuss how to generalize the present analysis beyond the linear
approximation in spin, including spin-squared corrections in the case of a
black-hole-like quadrupolar structure for the extended test body.
| [
{
"created": "Mon, 31 Jul 2017 12:24:48 GMT",
"version": "v1"
}
] | 2018-08-29 | [
[
"Bini",
"Donato",
""
],
[
"Geralico",
"Andrea",
""
],
[
"Vines",
"Justin",
""
]
] | We investigate the scattering of a spinning test particle by a Kerr black hole within the Mathisson-Papapetrou-Dixon model to linear order in spin. The particle's spin and orbital angular momentum are taken to be aligned with the black hole's spin. Both the particle's mass and spin length are assumed to be small in comparison with the characteristic length scale of the background curvature, in order to avoid backreaction effects. We analytically compute the modifications due to the particle's spin to the scattering angle, the periastron shift, and the condition for capture by the black hole, extending previous results valid for the nonrotating Schwarzschild background. Finally, we discuss how to generalize the present analysis beyond the linear approximation in spin, including spin-squared corrections in the case of a black-hole-like quadrupolar structure for the extended test body. |
1108.2296 | Stanley P. Gudder | Stan Gudder | Discrete Quantum Gravity | 19 pages which includes 3 figures created in LaTeX | null | null | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss the causal set approach to discrete quantum gravity. We begin by
describing a classical sequential growth process in which the universe grows
one element at a time in discrete steps. At each step the process has the form
of a causal set and the "completed" universe is given by a path through a
discretely growing chain of causal sets. We then introduce a method for
quantizing this classical formalism to obtain a quantum sequential growth
process which may lead to a viable model for a discrete quantum gravity. We
also give a method for quantizing random variables in the classical process to
obtain observables in the corresponding quantum process. The paper closes by
showing that a discrete isometric process can be employed to construct a
quantum sequential growth process.
| [
{
"created": "Wed, 10 Aug 2011 22:06:53 GMT",
"version": "v1"
}
] | 2011-08-12 | [
[
"Gudder",
"Stan",
""
]
] | We discuss the causal set approach to discrete quantum gravity. We begin by describing a classical sequential growth process in which the universe grows one element at a time in discrete steps. At each step the process has the form of a causal set and the "completed" universe is given by a path through a discretely growing chain of causal sets. We then introduce a method for quantizing this classical formalism to obtain a quantum sequential growth process which may lead to a viable model for a discrete quantum gravity. We also give a method for quantizing random variables in the classical process to obtain observables in the corresponding quantum process. The paper closes by showing that a discrete isometric process can be employed to construct a quantum sequential growth process. |
1502.00977 | Davood Momeni Dr | D. Momeni, R. Myrzakulov, E. G\"udekli | Cosmological viable Mimetic $f(R)$ and $f(R,T)$ theories via Noether
symmetry | Accepted in "International Journal of Geometric Methods in Modern
Physics",22 pages,no figure | Int.J.Geom.Meth.Mod.Phys. 12 (2015) no.10, 1550101 | 10.1142/S0219887815501017 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Extended $f(R)$ theories of gravity have been investigated from the symmetry
point of view. We briefly has been investigated Noether symmetry of two types
of extended $f(R)$ theories: $f(R,T)$ theory, in which curvature is coupled non
minimally to the trace of energy momentum tensor $T_{\mu\nu}$ and mimetic $f
(R) $ gravity, a theory with a scalar field degree of freedom, but ghost-free
and with internal conformal symmetry. In both cases we write point -like
Lagrangian for flat Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmological
background in the presence of ordinary matter. We have been shown that some
classes of models existed with Noether symmetry in these viable extensions of
$f(R)$ gravity. As a motivated idea, we have been investigating the stability
of the solutions and the bouncing and $\Lambda$CDM models using the Noether
symmetries. We have been shown that in mimetic $f(R)$ gravity bouncing and
$\Lambda$CDM solutions are possible. Also a class of solutions with future
singularities has been investigated.
| [
{
"created": "Mon, 19 Jan 2015 05:02:44 GMT",
"version": "v1"
},
{
"created": "Sun, 24 May 2015 15:47:57 GMT",
"version": "v2"
}
] | 2018-10-09 | [
[
"Momeni",
"D.",
""
],
[
"Myrzakulov",
"R.",
""
],
[
"Güdekli",
"E.",
""
]
] | Extended $f(R)$ theories of gravity have been investigated from the symmetry point of view. We briefly has been investigated Noether symmetry of two types of extended $f(R)$ theories: $f(R,T)$ theory, in which curvature is coupled non minimally to the trace of energy momentum tensor $T_{\mu\nu}$ and mimetic $f (R) $ gravity, a theory with a scalar field degree of freedom, but ghost-free and with internal conformal symmetry. In both cases we write point -like Lagrangian for flat Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmological background in the presence of ordinary matter. We have been shown that some classes of models existed with Noether symmetry in these viable extensions of $f(R)$ gravity. As a motivated idea, we have been investigating the stability of the solutions and the bouncing and $\Lambda$CDM models using the Noether symmetries. We have been shown that in mimetic $f(R)$ gravity bouncing and $\Lambda$CDM solutions are possible. Also a class of solutions with future singularities has been investigated. |
1501.05697 | Ramon Herrera | Sergio del Campo, Carlos Gonzalez and Ramon Herrera | Power law inflation with a non-minimally coupled scalar field in light
of Planck and BICEP2 data: The exact versus slow roll results | 13 pages and 1 figure | null | 10.1007/s10509-015-2414-4 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study power law inflation in the context of non-minimally coupled to the
scalar curvature. We analyze the inflationary solutions under an exact analysis
and also in the slow roll approximation. In both solutions, we consider the
recent data from Planck and BICEP2 data to constraint the parameter in our
model. We find that the slow roll approximation is disfavored in the presence
of non-minimal couplings during the power law expansion of the Universe.
| [
{
"created": "Fri, 23 Jan 2015 02:16:47 GMT",
"version": "v1"
}
] | 2015-08-06 | [
[
"del Campo",
"Sergio",
""
],
[
"Gonzalez",
"Carlos",
""
],
[
"Herrera",
"Ramon",
""
]
] | We study power law inflation in the context of non-minimally coupled to the scalar curvature. We analyze the inflationary solutions under an exact analysis and also in the slow roll approximation. In both solutions, we consider the recent data from Planck and BICEP2 data to constraint the parameter in our model. We find that the slow roll approximation is disfavored in the presence of non-minimal couplings during the power law expansion of the Universe. |
1312.3597 | Julio Oliva | Andres Anabalon, Adolfo Cisterna and Julio Oliva | Asymptotically locally AdS and flat black holes in Horndeski theory | 15 pages, 1 figure. v2: typos corrected, to appear on PRD | Phys. Rev. D 89, 084050 (2014) | 10.1103/PhysRevD.89.084050 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we construct asymptotically locally AdS and flat black holes in
the presence of a scalar field whose kinetic term is constructed out from a
linear combination of the metric and the Einstein tensor. The field equations
as well as the energy-momentum tensor are second order in the metric and the
field, therefore the theory belongs to the ones defined by Horndeski. We show
that in the presence of a cosmological term in the action, it is possible to
have a real scalar field in the region outside the event horizon. The solutions
are characterized by a single integration constant, the scalar field vanishes
at the horizon and it contributes to the effective cosmological constant at
infinity. We extend these results to the topological case. The solution is
disconnected from the maximally symmetric AdS background, however, within this
family there exits a gravitational soliton which is everywhere regular. This
soliton is therefore used as a background to define a finite Euclidean action
and to obtain the thermodynamics of the black holes. For a certain region in
the space of parameters, the thermodynamic analysis reveals a critical
temperature at which a Hawking-Page phase transition between the black hole and
the soliton occurs. We extend the solution to arbitrary dimensions grater than
four and show that the presence of a cosmological term in the action allows to
consider the case in which the standard kinetic term for the scalar it's not
present. In such scenario, the solution reduces to an asymptotically flat black
hole.
| [
{
"created": "Thu, 12 Dec 2013 19:27:43 GMT",
"version": "v1"
},
{
"created": "Tue, 25 Mar 2014 16:20:40 GMT",
"version": "v2"
}
] | 2014-04-23 | [
[
"Anabalon",
"Andres",
""
],
[
"Cisterna",
"Adolfo",
""
],
[
"Oliva",
"Julio",
""
]
] | In this paper we construct asymptotically locally AdS and flat black holes in the presence of a scalar field whose kinetic term is constructed out from a linear combination of the metric and the Einstein tensor. The field equations as well as the energy-momentum tensor are second order in the metric and the field, therefore the theory belongs to the ones defined by Horndeski. We show that in the presence of a cosmological term in the action, it is possible to have a real scalar field in the region outside the event horizon. The solutions are characterized by a single integration constant, the scalar field vanishes at the horizon and it contributes to the effective cosmological constant at infinity. We extend these results to the topological case. The solution is disconnected from the maximally symmetric AdS background, however, within this family there exits a gravitational soliton which is everywhere regular. This soliton is therefore used as a background to define a finite Euclidean action and to obtain the thermodynamics of the black holes. For a certain region in the space of parameters, the thermodynamic analysis reveals a critical temperature at which a Hawking-Page phase transition between the black hole and the soliton occurs. We extend the solution to arbitrary dimensions grater than four and show that the presence of a cosmological term in the action allows to consider the case in which the standard kinetic term for the scalar it's not present. In such scenario, the solution reduces to an asymptotically flat black hole. |
0804.4345 | Fabrizio Tamburini | Fabrizio Tamburini (1), Bruce A. Bassett (2) and Carlo Ungarelli (3)
((1) Dept. of Astronomy University of Padova, Vicolo dell'Osservatorio 3,
Padova, Italy. (2) SAAO / UCT, Observatory Road Observatory, Cape Town, South
Africa. (3) CNR IGG Pisa, Via G. Moruzzi 1, Pisa, Italy.) | The "Quantum Mousetrap": Entangled States and Gravitational Waves | 5 pages, 1 figure | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose a "thought technique" for detecting Gravitational Waves using
Einstein-Podolski-Rosen photon Entangled States. GWs decohere the entangled
photon pairs, introduce a relative rotation and de-synchronize Alice and Bob's
reference frames thus reducing the measured non-locality of correlated quanta
described by Bell's inequalities. Gravitational Waves, distorting quantum
encryption key statistics away from a pure white noise, act then as shadow
eavesdroppers. The deviation from the intrinsic white-noise randomness of a
Quantum Key Distribution process can reveal the presence of a gravitational
wave by analyzing the emerging color distortions in the key. Photon entangled
states provide the key advantage of revealing the polarization rotation
introduced by GWs without the need of previously fixed reference frames
| [
{
"created": "Mon, 28 Apr 2008 08:44:27 GMT",
"version": "v1"
}
] | 2008-04-29 | [
[
"Tamburini",
"Fabrizio",
""
],
[
"Bassett",
"Bruce A.",
""
],
[
"Ungarelli",
"Carlo",
""
]
] | We propose a "thought technique" for detecting Gravitational Waves using Einstein-Podolski-Rosen photon Entangled States. GWs decohere the entangled photon pairs, introduce a relative rotation and de-synchronize Alice and Bob's reference frames thus reducing the measured non-locality of correlated quanta described by Bell's inequalities. Gravitational Waves, distorting quantum encryption key statistics away from a pure white noise, act then as shadow eavesdroppers. The deviation from the intrinsic white-noise randomness of a Quantum Key Distribution process can reveal the presence of a gravitational wave by analyzing the emerging color distortions in the key. Photon entangled states provide the key advantage of revealing the polarization rotation introduced by GWs without the need of previously fixed reference frames |
1704.01934 | Tomasz Trze\'sniewski | Jakub Mielczarek, Tomasz Trze\'sniewski | Nonlinear Field Space Cosmology | 15 pages, 1 figure, v2 presentation improved and references added | Phys. Rev. D 96, 043522 (2017) | 10.1103/PhysRevD.96.043522 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the FRW cosmological model in which the matter content of
universe (playing a role of inflaton or quintessence) is given by a novel
generalization of the massive scalar field. The latter is a scalar version of
the recently introduced Nonlinear Field Space Theory (NFST), where physical
phase space of a given field is assumed to be compactified at large energies.
For our analysis we choose the simple case of a field with the spherical phase
space and endow it with the generalized Hamiltonian analogous to the XXZ
Heisenberg model, normally describing a system of spins in condensed matter
physics. Subsequently, we study both the homogenous cosmological sector and
linear perturbations of such a test field. In the homogenous sector we find
that nonlinearity of the field phase space is becoming relevant for large
volumes of universe and then it can lead to a recollapse, and possibly also at
very high energies, leading to the phase of a bounce. Quantization of the field
is performed in the limit where nontrivial nature of its phase space can be
neglected, while there is a non-vanishing contribution from the Lorentz
symmetry breaking term of the Hamiltonian. As a result, in the leading order of
the XXZ anisotropy parameter, we find that the inflationary spectral index
remains unmodified with respect to the standard case but the total amplitude of
perturbations is subject to a correction. The Bunch-Davies vacuum state also
becomes appropriately corrected. The proposed new approach is bringing
cosmology and condensed matter physics closer together, which may turn out to
be beneficial for both disciplines.
| [
{
"created": "Thu, 6 Apr 2017 17:02:13 GMT",
"version": "v1"
},
{
"created": "Fri, 1 Sep 2017 18:18:50 GMT",
"version": "v2"
}
] | 2017-09-05 | [
[
"Mielczarek",
"Jakub",
""
],
[
"Trześniewski",
"Tomasz",
""
]
] | We consider the FRW cosmological model in which the matter content of universe (playing a role of inflaton or quintessence) is given by a novel generalization of the massive scalar field. The latter is a scalar version of the recently introduced Nonlinear Field Space Theory (NFST), where physical phase space of a given field is assumed to be compactified at large energies. For our analysis we choose the simple case of a field with the spherical phase space and endow it with the generalized Hamiltonian analogous to the XXZ Heisenberg model, normally describing a system of spins in condensed matter physics. Subsequently, we study both the homogenous cosmological sector and linear perturbations of such a test field. In the homogenous sector we find that nonlinearity of the field phase space is becoming relevant for large volumes of universe and then it can lead to a recollapse, and possibly also at very high energies, leading to the phase of a bounce. Quantization of the field is performed in the limit where nontrivial nature of its phase space can be neglected, while there is a non-vanishing contribution from the Lorentz symmetry breaking term of the Hamiltonian. As a result, in the leading order of the XXZ anisotropy parameter, we find that the inflationary spectral index remains unmodified with respect to the standard case but the total amplitude of perturbations is subject to a correction. The Bunch-Davies vacuum state also becomes appropriately corrected. The proposed new approach is bringing cosmology and condensed matter physics closer together, which may turn out to be beneficial for both disciplines. |
gr-qc/9902042 | Esposito Giampiero | Ivan G. Avramidi and Giampiero Esposito | Foundational Problems in Quantum Gravity | 12 pages, plain Tex, contribution to the Italian XIII National
Conference on General Relativity, Monopoli, September 1998 | null | null | DSF preprint 99/6 | gr-qc | null | Boundary conditions play a crucial role in the path-integral approach to
quantum gravity and quantum cosmology, as well as in the current attempts to
understand the one-loop semiclassical properties of quantum field theories.
Within this framework, one is led to consider boundary conditions completely
invariant under infinitesimal diffeomorphisms on metric perturbations. These
are part of a general scheme, which can be developed for Maxwell theory,
Yang-Mills Theory, Rarita-Schwinger fields and any other gauge theory. A
general condition for strong ellipticity of the resulting field theory on
manifolds with boundary is here proved, following recent work by the authors.
The relevance for Euclidean quantum gravity is eventually discussed.
| [
{
"created": "Sat, 13 Feb 1999 15:15:26 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Avramidi",
"Ivan G.",
""
],
[
"Esposito",
"Giampiero",
""
]
] | Boundary conditions play a crucial role in the path-integral approach to quantum gravity and quantum cosmology, as well as in the current attempts to understand the one-loop semiclassical properties of quantum field theories. Within this framework, one is led to consider boundary conditions completely invariant under infinitesimal diffeomorphisms on metric perturbations. These are part of a general scheme, which can be developed for Maxwell theory, Yang-Mills Theory, Rarita-Schwinger fields and any other gauge theory. A general condition for strong ellipticity of the resulting field theory on manifolds with boundary is here proved, following recent work by the authors. The relevance for Euclidean quantum gravity is eventually discussed. |
1612.01272 | Jaume Haro | Llibert Arest\'e Sal\'o and Jaume de Haro | Cosmological solutions in spatially curved universes with adiabatic
particle production | 13 pages, 10 figures. Version accepted for publication in CQG | Class.Quant.Grav. 34 (2017) no.6, 065001 | 10.1088/1361-6382/aa5e14 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We perform a qualitative and thermodynamic study of two models when one takes
into account adiabatic particle production. In the first one, there is a
constant particle production rate, which leads to solutions depicting the
current cosmic acceleration but without inflation. The other one has solutions
that unify the early and late time acceleration. These solutions converge
asymptotically to the thermal equilibrium.
| [
{
"created": "Mon, 5 Dec 2016 08:27:52 GMT",
"version": "v1"
},
{
"created": "Thu, 2 Feb 2017 16:25:24 GMT",
"version": "v2"
}
] | 2017-03-13 | [
[
"Saló",
"Llibert Aresté",
""
],
[
"de Haro",
"Jaume",
""
]
] | We perform a qualitative and thermodynamic study of two models when one takes into account adiabatic particle production. In the first one, there is a constant particle production rate, which leads to solutions depicting the current cosmic acceleration but without inflation. The other one has solutions that unify the early and late time acceleration. These solutions converge asymptotically to the thermal equilibrium. |
gr-qc/0307032 | Enric Verdaguer | B. L. Hu, E. Verdaguer | Stochastic Gravity: Theory and Applications | 75 pages, no figures, submitted to Living Reviews in Relativity | Living Rev.Rel.7:3,2004 | 10.12942/lrr-2004-3 | null | gr-qc | null | Whereas semiclassical gravity is based on the semiclassical Einstein equation
with sources given by the expectation value of the stress-energy tensor of
quantum fields, stochastic semiclassical gravity is based on the
Einstein-Langevin equation, which has in addition sources due to the noise
kernel.In the first part, we describe the fundamentals of this new theory via
two approaches: the axiomatic and the functional. In the second part, we
describe three applications of stochastic gravity theory. First, we consider
metric perturbations in a Minkowski spacetime: we compute the two-point
correlation functions for the linearized Einstein tensor and for the metric
perturbations. Second, we discuss structure formation from the stochastic
gravity viewpoint. Third, we discuss the backreaction of Hawking radiation in
the gravitational background of a quasi-static black hole.
| [
{
"created": "Tue, 8 Jul 2003 15:00:51 GMT",
"version": "v1"
}
] | 2016-10-19 | [
[
"Hu",
"B. L.",
""
],
[
"Verdaguer",
"E.",
""
]
] | Whereas semiclassical gravity is based on the semiclassical Einstein equation with sources given by the expectation value of the stress-energy tensor of quantum fields, stochastic semiclassical gravity is based on the Einstein-Langevin equation, which has in addition sources due to the noise kernel.In the first part, we describe the fundamentals of this new theory via two approaches: the axiomatic and the functional. In the second part, we describe three applications of stochastic gravity theory. First, we consider metric perturbations in a Minkowski spacetime: we compute the two-point correlation functions for the linearized Einstein tensor and for the metric perturbations. Second, we discuss structure formation from the stochastic gravity viewpoint. Third, we discuss the backreaction of Hawking radiation in the gravitational background of a quasi-static black hole. |
1911.05983 | Renier Hough | Renier Hough, Amare Abebe, Stefan Ferreira | Viability tests of \textit{f(R)}-gravity models with Supernovae Type 1A
data | 15 pages, 13 figures, and 49 references. This is a re-submission [v3]
with updated references and fixed typing errors. We also added in a new
theoretical residuals plot, as well as adding two appendices to show the
mathematics that were needed. This work is based on Renier Hough's Masters
dissertation results | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we will be testing four different general \textit{f(R)}-gravity
models, two of which are the more realistic models (namely the Starobinsky and
the Hu-Sawicki models), to determine if they are viable alternative models to
pursue a more vigorous constraining test upon them. For the testing of these
models, we use 359 low- and intermediate-redshift Supernovae Type 1A data
obtained from thRede SDSS-II/SNLS2 Joint Light-curve Analysis (JLA). We develop
a Markov Chain Monte Carlo (MCMC) simulation to find a best-fitting function
within reasonable ranges for each \textit{f(R)}-gravity model, as well as for
the Lambda Cold Dark Matter ($\Lambda$CDM) model. For simplicity, we assume a
flat universe with a negligible radiation density distribution. Therefore, the
only difference between the accepted $\Lambda$CDM model and the
\textit{f(R)}-gravity models will be the dark energy term and the arbitrary
free parameters. By doing a statistical analysis and using the $\Lambda$CDM
model as our "true model", we can obtain an indication whether or not a certain
\textit{f(R)}-gravity model shows promise and requires a more in-depth view in
future studies. In our results, we found that the Starobinsky model obtained a
larger likelihood function value than the $\Lambda$CDM model, while still
obtaining the cosmological parameters to be $\Omega_{m} =
0.268^{+0.027}_{-0.024}$ for the matter density distribution and $\bar{h} =
0.690^{+0.005}_{-0.005}$ for the Hubble uncertainty parameter. We also found a
reduced Starobinsky model that are able to explain the data, as well as being
statistically significant.
| [
{
"created": "Thu, 14 Nov 2019 08:16:40 GMT",
"version": "v1"
},
{
"created": "Mon, 18 Nov 2019 14:58:58 GMT",
"version": "v2"
},
{
"created": "Tue, 23 Jun 2020 09:44:29 GMT",
"version": "v3"
}
] | 2020-06-24 | [
[
"Hough",
"Renier",
""
],
[
"Abebe",
"Amare",
""
],
[
"Ferreira",
"Stefan",
""
]
] | In this work, we will be testing four different general \textit{f(R)}-gravity models, two of which are the more realistic models (namely the Starobinsky and the Hu-Sawicki models), to determine if they are viable alternative models to pursue a more vigorous constraining test upon them. For the testing of these models, we use 359 low- and intermediate-redshift Supernovae Type 1A data obtained from thRede SDSS-II/SNLS2 Joint Light-curve Analysis (JLA). We develop a Markov Chain Monte Carlo (MCMC) simulation to find a best-fitting function within reasonable ranges for each \textit{f(R)}-gravity model, as well as for the Lambda Cold Dark Matter ($\Lambda$CDM) model. For simplicity, we assume a flat universe with a negligible radiation density distribution. Therefore, the only difference between the accepted $\Lambda$CDM model and the \textit{f(R)}-gravity models will be the dark energy term and the arbitrary free parameters. By doing a statistical analysis and using the $\Lambda$CDM model as our "true model", we can obtain an indication whether or not a certain \textit{f(R)}-gravity model shows promise and requires a more in-depth view in future studies. In our results, we found that the Starobinsky model obtained a larger likelihood function value than the $\Lambda$CDM model, while still obtaining the cosmological parameters to be $\Omega_{m} = 0.268^{+0.027}_{-0.024}$ for the matter density distribution and $\bar{h} = 0.690^{+0.005}_{-0.005}$ for the Hubble uncertainty parameter. We also found a reduced Starobinsky model that are able to explain the data, as well as being statistically significant. |
1102.2309 | Alessandro Fabbri | Alessandro Fabbri | The Hawking signal in density-density correlations in BECs | 4 pages, Contribution to the Proceedings of ERE2010 | J.Phys.Conf.Ser. 314:012029,2011 | 10.1088/1742-6596/314/1/012029 | null | gr-qc cond-mat.quant-gas hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We outline the derivation of the Hawking quanta-partner signal in
correlations, and highlight the specific application to detect it in
density-density correlations in BECs.
| [
{
"created": "Fri, 11 Feb 2011 09:55:44 GMT",
"version": "v1"
}
] | 2011-10-06 | [
[
"Fabbri",
"Alessandro",
""
]
] | We outline the derivation of the Hawking quanta-partner signal in correlations, and highlight the specific application to detect it in density-density correlations in BECs. |
1903.07473 | Theodosios Christodoulakis | T. Pailas and T. Christodoulakis | Dynamically equivalent {\Lambda}CDM equations with underlying Bianchi
Type geometry | 20 pages, 2 figures, Latex2e source file | null | 10.1088/1475-7516/2019/07/029 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Solutions have been found for gravity coupled to electromagnetic field and a
set of charged and uncharged perfect fluids for Bianchi Types VI_{(-1)}, VIII,
IX, under the primary assumption of the existence of a conformal Killing vector
field. The electromagnetic field ``absorbs'' the ``frozen'' anisotropy and the
remaining equations are dynamically equivalent with the equations of
{\Lambda}CDM. There are solutions with flat, negative and positive effective
spatial curvature corresponding to the three FLRW classes. Three equations of
state for the charged perfect fluid where studied: non-relativistic w=0,
relativistic w=\frac{1}{3} and dark energy-like w=-1. For the first two cases,
maximum values exist for the scale factor, in order for the weak energy
conditions to be respected, which depend upon the geometric and charged fluid
parameters. A minimum value for the scale factor exists (for the solutions to
be valid) in all the cases and Types, indicating the absence of initial
spacetime singularity (big bang). This minimum value depends upon the geometric
and electromagnetic parameters. The number of essential constants in the final
form of each metric is the minimum without loss of generality due to the use of
the constant Automorphism's group. A known solution, with the anisotropy
absorbed via one free scalar field is reproduced with our method and contains
the minimum possible number of parameters.
| [
{
"created": "Mon, 18 Mar 2019 14:29:18 GMT",
"version": "v1"
},
{
"created": "Tue, 6 Aug 2019 17:54:46 GMT",
"version": "v2"
}
] | 2019-08-07 | [
[
"Pailas",
"T.",
""
],
[
"Christodoulakis",
"T.",
""
]
] | Solutions have been found for gravity coupled to electromagnetic field and a set of charged and uncharged perfect fluids for Bianchi Types VI_{(-1)}, VIII, IX, under the primary assumption of the existence of a conformal Killing vector field. The electromagnetic field ``absorbs'' the ``frozen'' anisotropy and the remaining equations are dynamically equivalent with the equations of {\Lambda}CDM. There are solutions with flat, negative and positive effective spatial curvature corresponding to the three FLRW classes. Three equations of state for the charged perfect fluid where studied: non-relativistic w=0, relativistic w=\frac{1}{3} and dark energy-like w=-1. For the first two cases, maximum values exist for the scale factor, in order for the weak energy conditions to be respected, which depend upon the geometric and charged fluid parameters. A minimum value for the scale factor exists (for the solutions to be valid) in all the cases and Types, indicating the absence of initial spacetime singularity (big bang). This minimum value depends upon the geometric and electromagnetic parameters. The number of essential constants in the final form of each metric is the minimum without loss of generality due to the use of the constant Automorphism's group. A known solution, with the anisotropy absorbed via one free scalar field is reproduced with our method and contains the minimum possible number of parameters. |
gr-qc/9810011 | WU Zhong Chao | Wu Zhong Chao (Beijing Normal University) | Pair Creation of Black Holes in Anti-de Sitter Space Background (I) | 9 pages, minor change | Gen.Rel.Grav.31:223-231,1999 | 10.1023/A:1018896211493 | Beijing preprint 98-107 | gr-qc hep-th | null | For a spherically symmetric vacuum model with a negative cosmological
constant, a complex constrained instanton is considered as the seed for the
quantum pair creation of Schwarzschild-anti-de Sitter black holes. The relative
creation probability is found to be the exponential of the negative of the
black hole entropy. The black hole entropy is known to be one quarter of the
black hole horizon area. In the absence of a general no-boundary proposal for
open creation, the constrained instanton approach is used in treating both the
open and closed pair creations of black holes.
| [
{
"created": "Sun, 4 Oct 1998 20:22:57 GMT",
"version": "v1"
},
{
"created": "Wed, 7 Oct 1998 19:55:54 GMT",
"version": "v2"
},
{
"created": "Fri, 9 Oct 1998 15:26:40 GMT",
"version": "v3"
},
{
"created": "Wed, 14 Oct 1998 21:12:49 GMT",
"version": "v4"
},
{
"created": "Sun, 25 Oct 1998 20:13:54 GMT",
"version": "v5"
}
] | 2008-11-26 | [
[
"Chao",
"Wu Zhong",
"",
"Beijing Normal University"
]
] | For a spherically symmetric vacuum model with a negative cosmological constant, a complex constrained instanton is considered as the seed for the quantum pair creation of Schwarzschild-anti-de Sitter black holes. The relative creation probability is found to be the exponential of the negative of the black hole entropy. The black hole entropy is known to be one quarter of the black hole horizon area. In the absence of a general no-boundary proposal for open creation, the constrained instanton approach is used in treating both the open and closed pair creations of black holes. |
gr-qc/9910020 | hamid Reza Sepangi | K. Ghafoori-Tabrizi, S. S. Gousheh and H. R. Sepangi | On signature transition in Robertson-Walker cosmologies | 9 pages plus 4 postscript figures. To appear in the Int. J. Mod.
Phys. A | Int.J.Mod.Phys.A15:1521-1531,2000 | 10.1142/S0217751X00000689 | null | gr-qc hep-th | null | We analyse a classical model of gravitation coupled to a self interacting
scalar field. We show that, within the context of this model for
Robertson-Walker cosmologies, there exist solutions in the spatially non-flat
cases exhibiting transitions from a Euclidean to a Lorentzian spacetime. We
then discuss the conditions under which these signature changing solutions to
Einstein's field equations exist. In particular, we find that an upper bound
for the cosmological constant exists and that close to the signature changing
hypersurface, both the scale factor and the scalar field have to be constant.
Moreover we find that the signature changing solutions do not exist when the
scalar field is massless.
| [
{
"created": "Wed, 6 Oct 1999 15:49:37 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"Ghafoori-Tabrizi",
"K.",
""
],
[
"Gousheh",
"S. S.",
""
],
[
"Sepangi",
"H. R.",
""
]
] | We analyse a classical model of gravitation coupled to a self interacting scalar field. We show that, within the context of this model for Robertson-Walker cosmologies, there exist solutions in the spatially non-flat cases exhibiting transitions from a Euclidean to a Lorentzian spacetime. We then discuss the conditions under which these signature changing solutions to Einstein's field equations exist. In particular, we find that an upper bound for the cosmological constant exists and that close to the signature changing hypersurface, both the scale factor and the scalar field have to be constant. Moreover we find that the signature changing solutions do not exist when the scalar field is massless. |
1304.1775 | Vivien Raymond | the LIGO Scientific Collaboration, 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. Cavagli\`a, 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, 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.
D\'iaz, 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. Endr\"oczi, R. Engel,
T. Etzel, K. Evans, M. Evans, T. Evans, M. Factourovich, V. Fafone, S.
Fairhurst, B. F. Farr, W. M. Farr, M. Favata, D. Fazi, H. Fehrmann, D.
Feldbaum, F. Feroz, 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. G\'asp\'ar, 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. Gonz\'alez, M. L. Gorodetsky, S. Go{\ss}ler, 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, C.-J. Haster, 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. Kr\'olak, 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. L\"uck, A. P. Lundgren, J. Macarthur, E. Macdonald, B.
Machenschalk, M. MacInnis, D. M. Macleod, M. Mageswaran, K. Mailand, E.
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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. Men\'endez, R. A. Mercer, S. Meshkov, C. Messenger, M. S.
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Mori, S. R. Morriss, S. Mosca, K. Mossavi, B. Mours, C. M. Mow--Lowry, C. L.
Mueller, G. Mueller, S. Mukherjee, A. Mullavey, H. M\"uller-Ebhardt, J.
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Necula, J. Nelson, I. Neri, G. Newton, T. Nguyen, A. Nishizawa, A. Nitz, F.
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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.
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L. Pinard, I. M. Pinto, M. Pitkin, H. J. Pletsch, M. V. Plissi, R. Poggiani,
J. P\"old, F. Postiglione, C. Poux, M. Prato, V. Predoi, T. Prestegard, L. R.
Price, M. Prijatelj, M. Principe, S. Privitera, G. A. Prodi, L. G. Prokhorov,
O. Puncken, M. Punturo, P. Puppo, V. Quetschke, R. Quitzow-James, F. J. Raab,
D. S. Rabeling, I. R\'acz, 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.
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Rosi\'nska, C. R\"over, S. Rowan, A. R\"udiger, P. Ruggi, K. Ryan, F. Salemi,
L. Sammut, V. Sandberg, S. Sankar, V. Sannibale, L. Santamar\'ia, I.
Santiago-Prieto, G. Santostasi, E. Saracco, B. Sassolas, B. S. Sathyaprakash,
P. R. Saulson, R. L. Savage, R. Schilling, R. Schnabel, R. M. S. Schofield,
B. Schulz, B. F. Schutz, P. Schwinberg, J. Scott, S. M. Scott, F. Seifert, D.
Sellers, D. Sentenac, A. Sergeev, D. A. Shaddock, M. Shaltev, B. Shapiro, P.
Shawhan, D. H. Shoemaker, T. L Sidery, X. Siemens, D. Sigg, D. Simakov, A.
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Taylor, A. P. M. ter Braack, P. Thomas, K. A. Thorne, K. S. Thorne, E.
Thrane, A. Th\"uring, C. Titsler, K. V. Tokmakov, C. Tomlinson, A. Toncelli,
M. Tonelli, O. Torre, C. V. Torres, C. I. Torrie, E. Tournefier, F. Travasso,
G. Traylor, M. Tse, D. Ugolini, H. Vahlbruch, G. Vajente, J. F. J. van den
Brand, C. Van Den Broeck, S. van der Putten, A. A. van Veggel, S. Vass, M.
Vasuth, R. Vaulin, M. Vavoulidis, A. Vecchio, G. Vedovato, J. Veitch, P. J.
Veitch, K. Venkateswara, D. Verkindt, F. Vetrano, A. Vicer\'e, A. E. Villar,
J.-Y. Vinet, S. Vitale, H. Vocca, C. Vorvick, S. P. Vyatchanin, A. Wade, L.
Wade, M. Wade, S. J. Waldman, L. Wallace, Y. Wan, M. Wang, X. Wang, A.
Wanner, R. L. Ward, M. Was, M. Weinert, A. J. Weinstein, R. Weiss, T.
Welborn, L. Wen, P. Wessels, M. West, T. Westphal, K. Wette, J. T. Whelan, S.
E. Whitcomb, D. J. White, B. F. Whiting, K. Wiesner, C. Wilkinson, P. A.
Willems, L. Williams, R. Williams, B. Willke, M. Wimmer, L. Winkelmann, W.
Winkler, C. C. Wipf, A. G. Wiseman, H. Wittel, G. Woan, R. Wooley, J. Worden,
J. Yablon, I. Yakushin, H. Yamamoto, K. Yamamoto, C. C. Yancey, H. Yang, D.
Yeaton-Massey, S. Yoshida, M. Yvert, A. Zadro\.zny, M. Zanolin, J.-P. Zendri,
F. Zhang, L. Zhang, C. Zhao, N. Zotov, M. E. Zucker, J. Zweizig | Parameter estimation for compact binary coalescence signals with the
first generation gravitational-wave detector network | 23 pages, 18 figures. LIGO Document P1200021. See the announcement
for this paper on ligo.org at:
http://www.ligo.org/science/Publication-S6PE/index.php. For a repository of
data used in the publication, go to:
https://dcc.ligo.org/LIGO-P1200021/public; Modifications thanks to referee
reports | Phys. Rev. D 88, 062001 (2013) | 10.1103/PhysRevD.88.062001 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Compact binary systems with neutron stars or black holes are one of the most
promising sources for ground-based gravitational wave detectors. Gravitational
radiation encodes rich information about source physics; thus parameter
estimation and model selection are crucial analysis steps for any detection
candidate events. Detailed models of the anticipated waveforms enable inference
on several parameters, such as component masses, spins, sky location and
distance that are essential for new astrophysical studies of these sources.
However, accurate measurements of these parameters and discrimination of models
describing the underlying physics are complicated by artifacts in the data,
uncertainties in the waveform models and in the calibration of the detectors.
Here we report such measurements on a selection of simulated signals added
either in hardware or software to the data collected by the two LIGO
instruments and the Virgo detector during their most recent joint science run,
including a "blind injection" where the signal was not initially revealed to
the collaboration. We exemplify the ability to extract information about the
source physics on signals that cover the neutron star and black hole parameter
space over the individual mass range 1 Msun - 25 Msun and the full range of
spin parameters. The cases reported in this study provide a snap-shot of the
status of parameter estimation in preparation for the operation of advanced
detectors.
| [
{
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"version": "v1"
},
{
"created": "Sat, 27 Apr 2013 20:26:47 GMT",
"version": "v2"
},
{
"created": "Sun, 11 Aug 2013 07:32:37 GMT",
"version": "v3"
},
{
"created": "Tue, 22 Oct 2013 18:28:45 GMT",
"version": "v4"
}
] | 2013-12-02 | [
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"Pletsch",
"H. J.",
""
],
[
"Plissi",
"M. V.",
""
],
[
"Poggiani",
"R.",
""
],
[
"Pöld",
"J.",
""
],
[
"Postiglione",
"F.",
""
],
[
"Poux",
"C.",
""
],
[
"Prato",
"M.",
""
],
[
"Predoi",
"V.",
""
],
[
"Prestegard",
"T.",
""
],
[
"Price",
"L. R.",
""
],
[
"Prijatelj",
"M.",
""
],
[
"Principe",
"M.",
""
],
[
"Privitera",
"S.",
""
],
[
"Prodi",
"G. A.",
""
],
[
"Prokhorov",
"L. G.",
""
],
[
"Puncken",
"O.",
""
],
[
"Punturo",
"M.",
""
],
[
"Puppo",
"P.",
""
],
[
"Quetschke",
"V.",
""
],
[
"Quitzow-James",
"R.",
""
],
[
"Raab",
"F. J.",
""
],
[
"Rabeling",
"D. S.",
""
],
[
"Rácz",
"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.",
""
],
[
"Rosińska",
"D.",
""
],
[
"Röver",
"C.",
""
],
[
"Rowan",
"S.",
""
],
[
"Rüdiger",
"A.",
""
],
[
"Ruggi",
"P.",
""
],
[
"Ryan",
"K.",
""
],
[
"Salemi",
"F.",
""
],
[
"Sammut",
"L.",
""
],
[
"Sandberg",
"V.",
""
],
[
"Sankar",
"S.",
""
],
[
"Sannibale",
"V.",
""
],
[
"Santamaría",
"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.",
""
],
[
"Thüring",
"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.",
""
],
[
"Viceré",
"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.",
""
],
[
"Zadrożny",
"A.",
""
],
[
"Zanolin",
"M.",
""
],
[
"Zendri",
"J. -P.",
""
],
[
"Zhang",
"F.",
""
],
[
"Zhang",
"L.",
""
],
[
"Zhao",
"C.",
""
],
[
"Zotov",
"N.",
""
],
[
"Zucker",
"M. E.",
""
],
[
"Zweizig",
"J.",
""
]
] | Compact binary systems with neutron stars or black holes are one of the most promising sources for ground-based gravitational wave detectors. Gravitational radiation encodes rich information about source physics; thus parameter estimation and model selection are crucial analysis steps for any detection candidate events. Detailed models of the anticipated waveforms enable inference on several parameters, such as component masses, spins, sky location and distance that are essential for new astrophysical studies of these sources. However, accurate measurements of these parameters and discrimination of models describing the underlying physics are complicated by artifacts in the data, uncertainties in the waveform models and in the calibration of the detectors. Here we report such measurements on a selection of simulated signals added either in hardware or software to the data collected by the two LIGO instruments and the Virgo detector during their most recent joint science run, including a "blind injection" where the signal was not initially revealed to the collaboration. We exemplify the ability to extract information about the source physics on signals that cover the neutron star and black hole parameter space over the individual mass range 1 Msun - 25 Msun and the full range of spin parameters. The cases reported in this study provide a snap-shot of the status of parameter estimation in preparation for the operation of advanced detectors. |
1605.03458 | Behnam Pourhassan | J. Sadeghi, B. Pourhassan, M. Rostami | P - V Criticality of Logarithmic Corrected Dyonic Charged AdS Black Hole | 11 pages, 5 figures. References added. Revised according to PRD
report | Phys. Rev. D 94, 064006 (2016) | 10.1103/PhysRevD.94.064006 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we consider dyonic charged AdS black hole which is holographic
dual of a van der Waals fluid. We use logarithmic corrected entropy and study
thermodynamics of the black hole and show that holographic picture is still
valid. Critical behaviors and stability also discussed. Logarithmic corrections
arises due to thermal fluctuations which are important when size of black hole
be small. So, thermal fluctuations interpreted as quantum effect. It means that
we can see quantum effect of a black hole which is a gravitational system.
| [
{
"created": "Wed, 11 May 2016 14:33:00 GMT",
"version": "v1"
},
{
"created": "Sun, 15 May 2016 07:10:14 GMT",
"version": "v2"
},
{
"created": "Mon, 1 Aug 2016 05:57:29 GMT",
"version": "v3"
}
] | 2016-09-07 | [
[
"Sadeghi",
"J.",
""
],
[
"Pourhassan",
"B.",
""
],
[
"Rostami",
"M.",
""
]
] | In this paper, we consider dyonic charged AdS black hole which is holographic dual of a van der Waals fluid. We use logarithmic corrected entropy and study thermodynamics of the black hole and show that holographic picture is still valid. Critical behaviors and stability also discussed. Logarithmic corrections arises due to thermal fluctuations which are important when size of black hole be small. So, thermal fluctuations interpreted as quantum effect. It means that we can see quantum effect of a black hole which is a gravitational system. |
2210.01313 | Xiao Yan Chew | Xiao Yan Chew, Dong-han Yeom and Jose Luis Bl\'azquez-Salcedo | Properties of Scalar Hairy Black Holes and Scalarons with Asymmetric
Potential | 12 pages, 10 figures | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | In this paper we study the properties of black holes and scalarons in
Einstein gravity when it is minimally coupled to a scalar field $\phi$ with an
asymmetric potential $V(\phi)$, constructed in [Phys. Rev. D \textbf{73}
(2006), 084002] a few decades ago. $V(\phi)$ has been applied in the cosmology
to describe the quantum tunneling process from the false vacuum to the true
vacuum and contains a local maximum, a local minimum (false vacuum) and a
global minimum (true vacuum). In particular we focus on the asymptotically flat
solutions, which can be constructed by fixing appropriately the local minimum
of $V$. A branch of hairy black holes solutions emerge from the Schwarzschild
black hole, and we study the domain of existence of such configurations. They
can reach to a particle-like solution in the small horizon limit, i.e. the
scalarons. We study the stability of black holes and scalarons, showing that
all of them are unstable under radial perturbations.
| [
{
"created": "Tue, 4 Oct 2022 02:13:25 GMT",
"version": "v1"
}
] | 2022-10-05 | [
[
"Chew",
"Xiao Yan",
""
],
[
"Yeom",
"Dong-han",
""
],
[
"Blázquez-Salcedo",
"Jose Luis",
""
]
] | In this paper we study the properties of black holes and scalarons in Einstein gravity when it is minimally coupled to a scalar field $\phi$ with an asymmetric potential $V(\phi)$, constructed in [Phys. Rev. D \textbf{73} (2006), 084002] a few decades ago. $V(\phi)$ has been applied in the cosmology to describe the quantum tunneling process from the false vacuum to the true vacuum and contains a local maximum, a local minimum (false vacuum) and a global minimum (true vacuum). In particular we focus on the asymptotically flat solutions, which can be constructed by fixing appropriately the local minimum of $V$. A branch of hairy black holes solutions emerge from the Schwarzschild black hole, and we study the domain of existence of such configurations. They can reach to a particle-like solution in the small horizon limit, i.e. the scalarons. We study the stability of black holes and scalarons, showing that all of them are unstable under radial perturbations. |
0803.0121 | Plyatsko Roman | Roman Plyatsko, Oleksandr Stefanyshyn | On common solutions of Mathisson equations under different conditions | 10 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the context of investigations of possible highly relativistic motions of a
spinning particle in the gravitational field, which can be described by the
Mathisson equations under different supplementary condition, we analyze the
circular orbits in a Schwarzschild field. The very orbits most clearly
demonstrate the effect of the gravitational spin-orbit interaction on the
particle's motion. It is shown that the Mathisson equations under the
Frenkel-Mathisson and Tulczyjew-Dixon conditions have the common solutions
describing the highly relativistic circular orbits in the region
$r=3M(1+\delta), |\delta|\ll 1$. These orbits essentially differ from the
geodesic circular orbits in the same region, particularly by the value of the
particle's energy on the corresponding orbits.
| [
{
"created": "Mon, 3 Mar 2008 14:47:39 GMT",
"version": "v1"
}
] | 2008-03-04 | [
[
"Plyatsko",
"Roman",
""
],
[
"Stefanyshyn",
"Oleksandr",
""
]
] | In the context of investigations of possible highly relativistic motions of a spinning particle in the gravitational field, which can be described by the Mathisson equations under different supplementary condition, we analyze the circular orbits in a Schwarzschild field. The very orbits most clearly demonstrate the effect of the gravitational spin-orbit interaction on the particle's motion. It is shown that the Mathisson equations under the Frenkel-Mathisson and Tulczyjew-Dixon conditions have the common solutions describing the highly relativistic circular orbits in the region $r=3M(1+\delta), |\delta|\ll 1$. These orbits essentially differ from the geodesic circular orbits in the same region, particularly by the value of the particle's energy on the corresponding orbits. |
1409.2371 | Rituparno Goswami | Rituparno Goswami, Anne Marie Nzioki, Sunil. D. Maharaj and Sushant G.
Ghosh | Collapsing spherical stars in f(R) gravity | 11 pages, 8 figures, Revtex 4, Minor changes in text, Matches the
accepted version in Physical Review D | Phys. Rev. D 90, 084011 (2014) | 10.1103/PhysRevD.90.084011 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We perform a careful investigation of the problem of physically realistic
gravitational collapse of massive stars in f(R)-gravity. We show that the extra
matching conditions that arise in the modified gravity imposes strong
constraints on the stellar structure and thermodynamic properties. In our
opinion these constraints are unphysical. We prove that no homogeneous stars
with non-constant Ricci scalar can be matched smoothly with a static exterior
for any nonlinear function f(R). Therefore, these extra constraints make
classes of physically realistic collapse scenarios in general relativity,
non-admissible in these theories. We also find an exact solution for an
inhomogeneous collapsing star in the Starobinski model that obeys all the
energy and matching conditions. However, we argue that such solutions are
fine-tuned and unstable to matter perturbations. Possible consequences on black
hole physics and the cosmic censorship conjecture are also discussed.
| [
{
"created": "Mon, 8 Sep 2014 14:40:16 GMT",
"version": "v1"
},
{
"created": "Mon, 29 Sep 2014 14:07:50 GMT",
"version": "v2"
}
] | 2014-10-15 | [
[
"Goswami",
"Rituparno",
""
],
[
"Nzioki",
"Anne Marie",
""
],
[
"Maharaj",
"Sunil. D.",
""
],
[
"Ghosh",
"Sushant G.",
""
]
] | We perform a careful investigation of the problem of physically realistic gravitational collapse of massive stars in f(R)-gravity. We show that the extra matching conditions that arise in the modified gravity imposes strong constraints on the stellar structure and thermodynamic properties. In our opinion these constraints are unphysical. We prove that no homogeneous stars with non-constant Ricci scalar can be matched smoothly with a static exterior for any nonlinear function f(R). Therefore, these extra constraints make classes of physically realistic collapse scenarios in general relativity, non-admissible in these theories. We also find an exact solution for an inhomogeneous collapsing star in the Starobinski model that obeys all the energy and matching conditions. However, we argue that such solutions are fine-tuned and unstable to matter perturbations. Possible consequences on black hole physics and the cosmic censorship conjecture are also discussed. |
0807.2325 | Lukas Hollenstein | Lukas Hollenstein, Francisco S. N. Lobo | Exact solutions of f(R) gravity coupled to nonlinear electrodynamics | 14 pages, 6 figures, revtex4; minor changes & details added,
conclusions remain; accepted for publication in Phys. Rev. D | Phys.Rev. D78 (2008) 124007 | 10.1103/PhysRevD.78.124007 | null | gr-qc astro-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, exact solutions of static and spherically symmetric space-times
are analyzed in f(R) modified theories of gravity coupled to nonlinear
electrodynamics. Firstly, we restrict the metric fields to one degree of
freedom, considering the specific case of g_tt\g_rr = -1. Using the dual P
formalism of nonlinear electrodynamics an exact general solution is deduced in
terms of the structural function H_P. In particular, specific exact solutions
to the gravitational field equations are found, confirming previous results and
new pure electric field solutions are found. Secondly, motivated by the
existence of regular electric fields at the center, and allowing for the case
of g_tt\g_rr \= -1, new specific solutions are found. Finally, we outline
alternative approaches by considering the specific case of constant curvature,
followed by the analysis of a specific form for f(R).
| [
{
"created": "Tue, 15 Jul 2008 11:25:47 GMT",
"version": "v1"
},
{
"created": "Fri, 14 Nov 2008 16:50:53 GMT",
"version": "v2"
}
] | 2012-06-22 | [
[
"Hollenstein",
"Lukas",
""
],
[
"Lobo",
"Francisco S. N.",
""
]
] | In this work, exact solutions of static and spherically symmetric space-times are analyzed in f(R) modified theories of gravity coupled to nonlinear electrodynamics. Firstly, we restrict the metric fields to one degree of freedom, considering the specific case of g_tt\g_rr = -1. Using the dual P formalism of nonlinear electrodynamics an exact general solution is deduced in terms of the structural function H_P. In particular, specific exact solutions to the gravitational field equations are found, confirming previous results and new pure electric field solutions are found. Secondly, motivated by the existence of regular electric fields at the center, and allowing for the case of g_tt\g_rr \= -1, new specific solutions are found. Finally, we outline alternative approaches by considering the specific case of constant curvature, followed by the analysis of a specific form for f(R). |
2302.09148 | Ernesto Contreras | Roberto Avalos, Ernesto Contreras | Quasi Normal Modes of hairy black holes at higher--order WKB approach | null | Eur. Phys. J. C 83, 155 (2023) | 10.1140/epjc/s10052-023-11288-2 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we implement the $13^{th}$ order semi-analytical WKB method to
explore the stability of hairy black holes obtained in the framework of
Gravitational Decoupling. In particular, we perform a detailed analysis of the
frequencies of the quasi-normal modes as a function of the primary hair of the
solutions with the aim to bound their values. We explore a broad interval in a
step of 0.1 of the hair parameters. We find that except for some cases where
the method is expected to have poor accuracy, all the solutions seem to be
stable and the role played by the primary hair is twofold: to modulate the
damping factor of the perturbation and to decrease the frequency of its
oscillation.
| [
{
"created": "Fri, 17 Feb 2023 21:18:37 GMT",
"version": "v1"
}
] | 2023-02-21 | [
[
"Avalos",
"Roberto",
""
],
[
"Contreras",
"Ernesto",
""
]
] | In this work, we implement the $13^{th}$ order semi-analytical WKB method to explore the stability of hairy black holes obtained in the framework of Gravitational Decoupling. In particular, we perform a detailed analysis of the frequencies of the quasi-normal modes as a function of the primary hair of the solutions with the aim to bound their values. We explore a broad interval in a step of 0.1 of the hair parameters. We find that except for some cases where the method is expected to have poor accuracy, all the solutions seem to be stable and the role played by the primary hair is twofold: to modulate the damping factor of the perturbation and to decrease the frequency of its oscillation. |
gr-qc/0111057 | Antony C. Searle | Susan M Scott, Benjamin J K Evans and Antony C Searle | GRworkbench: A Computational System Based on Differential Geometry | 10 pages, 4 figures, submitted to Proceedings of the Ninth Marcel
Grossmann Meeting | null | 10.1142/9789812777386_0031 | null | gr-qc | null | We have developed a new tool for numerical work in General Relativity:
GRworkbench. While past tools have been ad hoc, GRworkbench closely follows the
framework of Differential Geometry to provide a robust and general way of
computing on analytically defined space-times. We discuss the relationship
between Differential Geometry and C++ classes in GRworkbench, and demonstrate
their utility.
| [
{
"created": "Mon, 19 Nov 2001 00:41:00 GMT",
"version": "v1"
}
] | 2017-08-23 | [
[
"Scott",
"Susan M",
""
],
[
"Evans",
"Benjamin J K",
""
],
[
"Searle",
"Antony C",
""
]
] | We have developed a new tool for numerical work in General Relativity: GRworkbench. While past tools have been ad hoc, GRworkbench closely follows the framework of Differential Geometry to provide a robust and general way of computing on analytically defined space-times. We discuss the relationship between Differential Geometry and C++ classes in GRworkbench, and demonstrate their utility. |
1507.07726 | Shahab Shahidi | Zahra Haghani, Maryam Shiravand and Shahab Shahidi | Energy conditions in mimetic-$f(R)$ gravity | 14 pages | IJMPD 27 (2018) 1850049 | 10.1142/S0218271818500499 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The energy conditions of mimetic-$f(R)$ gravity theory is analyzed. We will
obtain the parameter space of the theory in some special forms of $f(R)$ in
which the self-acceleration is allowed. In this sense, the parameter space is
obtained in a way that it violates the strong energy condition while satisfying
the weak, null and dominant energy conditions. We will also consider the
condition that the Dolgov-Kawasaki instability is avoided. This condition will
be further imposed in the parameter space of the theory. We will show that the
parameter space of the mimetic-$f(R)$ gravity is larger than $f(R)$ gravity
theory.
| [
{
"created": "Tue, 28 Jul 2015 11:10:41 GMT",
"version": "v1"
},
{
"created": "Tue, 19 Apr 2016 04:30:54 GMT",
"version": "v2"
},
{
"created": "Fri, 8 Dec 2017 13:50:34 GMT",
"version": "v3"
}
] | 2018-02-26 | [
[
"Haghani",
"Zahra",
""
],
[
"Shiravand",
"Maryam",
""
],
[
"Shahidi",
"Shahab",
""
]
] | The energy conditions of mimetic-$f(R)$ gravity theory is analyzed. We will obtain the parameter space of the theory in some special forms of $f(R)$ in which the self-acceleration is allowed. In this sense, the parameter space is obtained in a way that it violates the strong energy condition while satisfying the weak, null and dominant energy conditions. We will also consider the condition that the Dolgov-Kawasaki instability is avoided. This condition will be further imposed in the parameter space of the theory. We will show that the parameter space of the mimetic-$f(R)$ gravity is larger than $f(R)$ gravity theory. |
2009.09846 | Markus Lazar | Markus Lazar | Gradient modification of Newtonian gravity | 9 pages, 4 figures | Phys. Rev. D 102, 096002 (2020) | 10.1103/PhysRevD.102.096002 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A second gradient generalization of Newtonian gravity is presented within the
framework of gradient field theory. Weak nonlocality is introduced via first
and second gradients of the gravitational field strength in the Lagrangian
density. Gradient generalizations of the Poisson equation of Newtonian
gravitation for the gravitational potential and of the generalized Gauss law
for the gravitational field strength are presented. Such a gradient
modification of Newtonian gravity provides a straightforward regularization of
Newtonian gravity removing the classical Newtonian singularities. Finite
gradient modifications of the gravitational potential energy and of the
gravitational force law are constructed, with a possible connection to Yukawa
interaction, and as suitable candidates for experimental tests of Newton's
inverse-square law at short distances. In addition, nonlocal gravity of
exponential type is investigated and its relation to gradient gravity theory is
given.
| [
{
"created": "Wed, 16 Sep 2020 17:05:09 GMT",
"version": "v1"
},
{
"created": "Wed, 30 Sep 2020 11:21:52 GMT",
"version": "v2"
},
{
"created": "Tue, 1 Dec 2020 18:21:03 GMT",
"version": "v3"
}
] | 2020-12-02 | [
[
"Lazar",
"Markus",
""
]
] | A second gradient generalization of Newtonian gravity is presented within the framework of gradient field theory. Weak nonlocality is introduced via first and second gradients of the gravitational field strength in the Lagrangian density. Gradient generalizations of the Poisson equation of Newtonian gravitation for the gravitational potential and of the generalized Gauss law for the gravitational field strength are presented. Such a gradient modification of Newtonian gravity provides a straightforward regularization of Newtonian gravity removing the classical Newtonian singularities. Finite gradient modifications of the gravitational potential energy and of the gravitational force law are constructed, with a possible connection to Yukawa interaction, and as suitable candidates for experimental tests of Newton's inverse-square law at short distances. In addition, nonlocal gravity of exponential type is investigated and its relation to gradient gravity theory is given. |
gr-qc/0404047 | Bogdan Serbanoiu | Bogdan C. Serbanoiu | About Brill Initial Data Sets and HPC | 5 pages, 1 figure | null | null | null | gr-qc | null | The goal of this paper is to present the physics behind Brill initial data
sets as an excellent tool for numerical experiments of axisymmetric spacetimes,
data sets which are practical applications of HPC for numerical solutions of
Einstein's vacuum equations.
| [
{
"created": "Fri, 9 Apr 2004 23:01:00 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Apr 2004 15:47:07 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Serbanoiu",
"Bogdan C.",
""
]
] | The goal of this paper is to present the physics behind Brill initial data sets as an excellent tool for numerical experiments of axisymmetric spacetimes, data sets which are practical applications of HPC for numerical solutions of Einstein's vacuum equations. |
1812.09644 | Warner A. Miller | Warner A. Miller, Paul M. Alsing, Doyeol Ahn | Higher dimensional quantum communication in a curved spacetime: an
efficient simulation of the propagation of the wavefront of a photon | 20 pages, 7 figures | Proc. SPIE 10660, Quantum Information Science, Sensing, and
Computation X, 106600M (16 May 2018); | 10.1117/12.2305060 | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A photon with a modulated wavefront can produce a quantum communication
channel in a larger Hilbert space. For example, higher dimensional quantum key
distribution (HD-QKD) can encode information in the transverse linear momentum
(LM) or orbital angular momentum (OAM) modes of a photon. This is markedly
different than using the intrinsic polarization of a photon. HD-QKD has
advantages for free space QKD since it can increase the communication
channel\~Os tolerance to bit error rate (BER) while maintaining or increasing
the channels bandwidth. We describe an efficient numerical simulation of the
propagation photon with an arbitrary complex wavefront in a material with an
isotropic but inhomogeneous index of refraction. We simulate the waveform
propagation of an optical vortex in a volume holographic element in the
paraxial approximation using an operator splitting method. We use this code to
analyze an OAM volume-holographic sorter. Furthermore, there are analogue
models of the evolution of a wavefront in the curved spacetime environs of the
Earth that can be constructed using an optical medium with a given index of
refraction. This can lead to a work-bench realization of a satellite HD-QKD
system.
| [
{
"created": "Sun, 23 Dec 2018 02:55:59 GMT",
"version": "v1"
}
] | 2018-12-27 | [
[
"Miller",
"Warner A.",
""
],
[
"Alsing",
"Paul M.",
""
],
[
"Ahn",
"Doyeol",
""
]
] | A photon with a modulated wavefront can produce a quantum communication channel in a larger Hilbert space. For example, higher dimensional quantum key distribution (HD-QKD) can encode information in the transverse linear momentum (LM) or orbital angular momentum (OAM) modes of a photon. This is markedly different than using the intrinsic polarization of a photon. HD-QKD has advantages for free space QKD since it can increase the communication channel\~Os tolerance to bit error rate (BER) while maintaining or increasing the channels bandwidth. We describe an efficient numerical simulation of the propagation photon with an arbitrary complex wavefront in a material with an isotropic but inhomogeneous index of refraction. We simulate the waveform propagation of an optical vortex in a volume holographic element in the paraxial approximation using an operator splitting method. We use this code to analyze an OAM volume-holographic sorter. Furthermore, there are analogue models of the evolution of a wavefront in the curved spacetime environs of the Earth that can be constructed using an optical medium with a given index of refraction. This can lead to a work-bench realization of a satellite HD-QKD system. |
2004.01038 | Rahul Kumar | Shafqat Ul Islam, Rahul Kumar, and Sushant G. Ghosh | Gravitational lensing by black holes in the $4D$ Einstein-Gauss-Bonnet
gravity | 14 pages, 6 figures, and 2 tables. Matched with the published version | JCAP 09, 030 (2020) | 10.1088/1475-7516/2020/09/030 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, a non-trivial $4D$ Einstein-Gauss-Bonnet (EGB) theory of gravity,
by rescaling the GB coupling parameter as $\alpha/(D-4)$, was formulated in
\cite{Glavan:2019inb}, which bypasses Lovelock's theorem and avoids
Ostrogradsky instability. The theory admits a static spherically symmetric
black hole, unlike $5D$ EGB or general relativity counterpart, which can have
both Cauchy and event horizons. We generalize previous work, on gravitational
lensing by a Schwarzschild black hole, in the strong and weak deflection limits
to the $4D$ EGB black holes to calculate the deflection coefficients $\bar{a}$
and $\bar{b}$, while former increases and later decrease with increasing
$\alpha$. We also find that the deflection angle $\alpha_D$, angular position
$\theta_{\infty}$ and $u_{m}$ decreases, but angular separation $s$ increases
with $\alpha$. The effect of the GB coupling parameter $\alpha$ on positions
and magnification of the source relativistic images is discussed in the context
of SgrA* and M87* black holes. A brief description of the weak gravitational
lensing using the Gauss-Bonnet theorem is presented.
| [
{
"created": "Thu, 2 Apr 2020 14:36:08 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Apr 2020 09:18:40 GMT",
"version": "v2"
},
{
"created": "Wed, 16 Sep 2020 15:43:02 GMT",
"version": "v3"
}
] | 2020-09-17 | [
[
"Islam",
"Shafqat Ul",
""
],
[
"Kumar",
"Rahul",
""
],
[
"Ghosh",
"Sushant G.",
""
]
] | Recently, a non-trivial $4D$ Einstein-Gauss-Bonnet (EGB) theory of gravity, by rescaling the GB coupling parameter as $\alpha/(D-4)$, was formulated in \cite{Glavan:2019inb}, which bypasses Lovelock's theorem and avoids Ostrogradsky instability. The theory admits a static spherically symmetric black hole, unlike $5D$ EGB or general relativity counterpart, which can have both Cauchy and event horizons. We generalize previous work, on gravitational lensing by a Schwarzschild black hole, in the strong and weak deflection limits to the $4D$ EGB black holes to calculate the deflection coefficients $\bar{a}$ and $\bar{b}$, while former increases and later decrease with increasing $\alpha$. We also find that the deflection angle $\alpha_D$, angular position $\theta_{\infty}$ and $u_{m}$ decreases, but angular separation $s$ increases with $\alpha$. The effect of the GB coupling parameter $\alpha$ on positions and magnification of the source relativistic images is discussed in the context of SgrA* and M87* black holes. A brief description of the weak gravitational lensing using the Gauss-Bonnet theorem is presented. |
gr-qc/0503086 | Jorge Pullin | Jorge Pullin | Matters of Gravity, the newsletter of the Topical Group on Gravitation
of the Americal Physical Society | 18 pages, 1 figure | null | null | MOG-25 | gr-qc | null | GGR News:
Message from the Chair, by Jim Isenberg
Einstein@Home, by Bernard Schutz
We hear that..., by Jorge Pullin
100 Years ago, by Jorge Pullin
Research Briefs:
What's new in LIGO, by David Shoemaker
Frame-dragging in the news in 2004, by Cliff Will
Cosmic (super)strings and LIGO, by Xavier Siemens
Conference reports:
The first gulf coast gravity conference, by Richard Price
Imagining the future, by Shane Larson
VI Mexican School, by Alejandro Corichi
| [
{
"created": "Sun, 20 Mar 2005 22:16:51 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Pullin",
"Jorge",
""
]
] | GGR News: Message from the Chair, by Jim Isenberg Einstein@Home, by Bernard Schutz We hear that..., by Jorge Pullin 100 Years ago, by Jorge Pullin Research Briefs: What's new in LIGO, by David Shoemaker Frame-dragging in the news in 2004, by Cliff Will Cosmic (super)strings and LIGO, by Xavier Siemens Conference reports: The first gulf coast gravity conference, by Richard Price Imagining the future, by Shane Larson VI Mexican School, by Alejandro Corichi |
2308.00627 | Hemily Gomes Marciano Fortes | Jos\'e C. N. de Araujo, Hemily G. M. Fortes | Compact stars in $f(T) = T +\xi T^\beta$ gravity | null | The European Physical Journal C, Volume 83, article number 1168,
(2023) | 10.1140/epjc/s10052-023-12342-9 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The Teleparallel Theory is equivalent to General Relativity, but whereas in
the latter gravity has to do with curvature, in the former gravity is described
by torsion. As is well known, there is in the literature a host of alternative
theories of gravity, among them the so called extended theories, in which
additional terms are added to the action, such as for example in the $f(R)$ and
$f(T)$ gravities, where $R$ is the Ricci scalar and $T$ is the scalar torsion,
respectively. One of the ways to probe alternative gravity is via compact
objects. In fact, there is in the literature a series of papers on compact
objects in $f(R)$ and $f(T)$ gravity. In particular, there are several papers
that consider $f(T) = T + \xi T^2$, where $\xi$ is a real constant. In this
paper, we generalise such extension considering compact stars in $f (T ) = T +
\xi T^\beta$ gravity, where $\xi$ and $\beta$ are real constants and looking
out for the implications in their maximum masses and compactness in comparison
to the General Relativity. Also, we are led to constrain the $\beta$ parameter
to positive integers which is a restriction not imposed by cosmology.
| [
{
"created": "Tue, 1 Aug 2023 15:55:39 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Jan 2024 18:00:29 GMT",
"version": "v2"
}
] | 2024-01-05 | [
[
"de Araujo",
"José C. N.",
""
],
[
"Fortes",
"Hemily G. M.",
""
]
] | The Teleparallel Theory is equivalent to General Relativity, but whereas in the latter gravity has to do with curvature, in the former gravity is described by torsion. As is well known, there is in the literature a host of alternative theories of gravity, among them the so called extended theories, in which additional terms are added to the action, such as for example in the $f(R)$ and $f(T)$ gravities, where $R$ is the Ricci scalar and $T$ is the scalar torsion, respectively. One of the ways to probe alternative gravity is via compact objects. In fact, there is in the literature a series of papers on compact objects in $f(R)$ and $f(T)$ gravity. In particular, there are several papers that consider $f(T) = T + \xi T^2$, where $\xi$ is a real constant. In this paper, we generalise such extension considering compact stars in $f (T ) = T + \xi T^\beta$ gravity, where $\xi$ and $\beta$ are real constants and looking out for the implications in their maximum masses and compactness in comparison to the General Relativity. Also, we are led to constrain the $\beta$ parameter to positive integers which is a restriction not imposed by cosmology. |
1210.3775 | M Blagojevi\'c | Milutin Blagojevi\'c and Friedrich W. Hehl | Gauge Theories of Gravitation | Latex, 165 pages, 10 figures, a guide to gauge theories of gravity;
v3: pdf submission, v4: Latex, v5: minor corrections | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | During the last five decades, gravity, as one of the fundamental forces of
nature, has been formulated as a gauge theory of the Weyl-Cartan-Yang-Mills
type. The present text offers commentaries on the articles from the most
prominent proponents of the theory. In the early 1960s, the gauge idea was
successfully applied to the Poincar\'e group of spacetime symmetries and to the
related conserved energy-momentum and angular momentum currents. The resulting
theory, the Poincar\'e gauge theory, encompasses Einstein's general relativity
as well as the teleparallel theory of gravity as subcases. The spacetime
structure is enriched by Cartan's torsion, and the new theory can accommodate
fermionic matter and its spin in a perfectly natural way. This guided tour
starts from special relativity and leads, in its first part, to general
relativity and its gauge type extensions \`a la Weyl and Cartan. Subsequent
stopping points are the theories of Yang-Mills and Utiyama and, as a particular
vantage point, the theory of Sciama and Kibble. Later, the Poincar\'e gauge
theory and its generalizations are explored and special topics, such as its
Hamiltonian formulation and exact solutions, are studied. This guide to the
literature on classical gauge theories of gravity is intended to be a
stimulating introduction to the subject.
| [
{
"created": "Sun, 14 Oct 2012 09:56:32 GMT",
"version": "v1"
},
{
"created": "Mon, 18 Mar 2013 11:20:25 GMT",
"version": "v2"
},
{
"created": "Tue, 17 Apr 2018 06:12:37 GMT",
"version": "v3"
},
{
"created": "Thu, 14 Apr 2022 10:32:47 GMT",
"version": "v4"
},
{
"created": "Sun, 8 May 2022 11:59:21 GMT",
"version": "v5"
}
] | 2022-05-10 | [
[
"Blagojević",
"Milutin",
""
],
[
"Hehl",
"Friedrich W.",
""
]
] | During the last five decades, gravity, as one of the fundamental forces of nature, has been formulated as a gauge theory of the Weyl-Cartan-Yang-Mills type. The present text offers commentaries on the articles from the most prominent proponents of the theory. In the early 1960s, the gauge idea was successfully applied to the Poincar\'e group of spacetime symmetries and to the related conserved energy-momentum and angular momentum currents. The resulting theory, the Poincar\'e gauge theory, encompasses Einstein's general relativity as well as the teleparallel theory of gravity as subcases. The spacetime structure is enriched by Cartan's torsion, and the new theory can accommodate fermionic matter and its spin in a perfectly natural way. This guided tour starts from special relativity and leads, in its first part, to general relativity and its gauge type extensions \`a la Weyl and Cartan. Subsequent stopping points are the theories of Yang-Mills and Utiyama and, as a particular vantage point, the theory of Sciama and Kibble. Later, the Poincar\'e gauge theory and its generalizations are explored and special topics, such as its Hamiltonian formulation and exact solutions, are studied. This guide to the literature on classical gauge theories of gravity is intended to be a stimulating introduction to the subject. |
1812.04846 | Cosimo Bambi | Carlos A. Benavides-Gallego, Ahmadjon Abdujabbarov, Daniele
Malafarina, Bobomurat Ahmedov, Cosimo Bambi | Charged particle motion and electromagnetic field in $\gamma$ spacetime | 14 pages, 9 figures. v2: refereed version | Phys. Rev. D 99, 044012 (2019) | 10.1103/PhysRevD.99.044012 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the electromagnetic field occurring in the background of a
static, axially symmetric vacuum solution of Einstein's field equations
immersed in an external magnetic field. The solution, known as the $\gamma$
metric (or Zipoy-Voorhees), is related to the Schwarzschild spacetime through a
real positive parameter $\gamma$ that describes its departure from spherical
symmetry. We study the motion of charged and uncharged particles in this
spacetime and particle collision in the vicinity of the singular surface and
compare with the corresponding result for Schwarzschild. We show that there is
a sharp contrast with the black hole case; in particular, in the prolate case
($\gamma<1$) particle collision can occur with an arbitrarily high center of
mass energy. This mechanism could in principle allow one to distinguish such a
source from a black hole.
| [
{
"created": "Wed, 12 Dec 2018 08:26:32 GMT",
"version": "v1"
},
{
"created": "Tue, 12 Feb 2019 14:47:22 GMT",
"version": "v2"
}
] | 2019-02-13 | [
[
"Benavides-Gallego",
"Carlos A.",
""
],
[
"Abdujabbarov",
"Ahmadjon",
""
],
[
"Malafarina",
"Daniele",
""
],
[
"Ahmedov",
"Bobomurat",
""
],
[
"Bambi",
"Cosimo",
""
]
] | We consider the electromagnetic field occurring in the background of a static, axially symmetric vacuum solution of Einstein's field equations immersed in an external magnetic field. The solution, known as the $\gamma$ metric (or Zipoy-Voorhees), is related to the Schwarzschild spacetime through a real positive parameter $\gamma$ that describes its departure from spherical symmetry. We study the motion of charged and uncharged particles in this spacetime and particle collision in the vicinity of the singular surface and compare with the corresponding result for Schwarzschild. We show that there is a sharp contrast with the black hole case; in particular, in the prolate case ($\gamma<1$) particle collision can occur with an arbitrarily high center of mass energy. This mechanism could in principle allow one to distinguish such a source from a black hole. |
2312.08588 | Hengrui Zhu | Hengrui Zhu, Harrison Siegel, Keefe Mitman, Maximiliano Isi, Will M.
Farr, Michael Boyle, Nils Deppe, Lawrence E. Kidder, Sizheng Ma, Jordan
Moxon, Kyle C. Nelli, Harald P. Pfeiffer, Mark A. Scheel, Saul A. Teukolsky,
William Throwe, Vijay Varma, and Nils L. Vu | Black Hole Spectroscopy for Precessing Binary Black Hole Coalescences | Data Release and Analysis Scripts:
https://github.com/HengruiPrinceton/precession_ringdown | null | null | null | gr-qc astro-ph.CO astro-ph.SR | http://creativecommons.org/licenses/by/4.0/ | The spectroscopic study of black hole quasinormal modes in gravitational-wave
ringdown observations is hindered by our ignorance of which modes should
dominate astrophysical signals for different binary configurations, limiting
tests of general relativity and astrophysics. In this work, we present a
description of the quasinormal modes that are excited in the ringdowns of
comparable mass, quasi-circular precessing binary black hole coalescences -- a
key region of parameter space that has yet to be fully explored within the
framework of black hole spectroscopy. We suggest that the remnant perturbation
for precessing and non-precessing systems is approximately the same up to a
rotation, which implies that the relative amplitudes of the quasinormal modes
in both systems are also related by a rotation. We present evidence for this by
analyzing an extensive catalog of numerical relativity simulations. Additional
structure in the amplitudes is connected to the system's kick velocity and
other asymmetries in the orbital dynamics. We find that the ringdowns of
precessing systems need not be dominated by the ${(\ell,m)=(2,\pm 2)}$
quasinormal modes, and that instead the $(2,\pm 1)$~or~$(2,0)$ quasinormal
modes can dominate. Our results are consistent with a ringdown analysis of the
LIGO-Virgo gravitational wave signal GW190521, and may also help in
understanding phenomenological inspiral-merger-ringdown waveform model
systematics.
| [
{
"created": "Thu, 14 Dec 2023 01:19:38 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Jul 2024 20:57:03 GMT",
"version": "v2"
}
] | 2024-07-22 | [
[
"Zhu",
"Hengrui",
""
],
[
"Siegel",
"Harrison",
""
],
[
"Mitman",
"Keefe",
""
],
[
"Isi",
"Maximiliano",
""
],
[
"Farr",
"Will M.",
""
],
[
"Boyle",
"Michael",
""
],
[
"Deppe",
"Nils",
""
],
[
"Kidder",
"Lawrence E.",
""
],
[
"Ma",
"Sizheng",
""
],
[
"Moxon",
"Jordan",
""
],
[
"Nelli",
"Kyle C.",
""
],
[
"Pfeiffer",
"Harald P.",
""
],
[
"Scheel",
"Mark A.",
""
],
[
"Teukolsky",
"Saul A.",
""
],
[
"Throwe",
"William",
""
],
[
"Varma",
"Vijay",
""
],
[
"Vu",
"Nils L.",
""
]
] | The spectroscopic study of black hole quasinormal modes in gravitational-wave ringdown observations is hindered by our ignorance of which modes should dominate astrophysical signals for different binary configurations, limiting tests of general relativity and astrophysics. In this work, we present a description of the quasinormal modes that are excited in the ringdowns of comparable mass, quasi-circular precessing binary black hole coalescences -- a key region of parameter space that has yet to be fully explored within the framework of black hole spectroscopy. We suggest that the remnant perturbation for precessing and non-precessing systems is approximately the same up to a rotation, which implies that the relative amplitudes of the quasinormal modes in both systems are also related by a rotation. We present evidence for this by analyzing an extensive catalog of numerical relativity simulations. Additional structure in the amplitudes is connected to the system's kick velocity and other asymmetries in the orbital dynamics. We find that the ringdowns of precessing systems need not be dominated by the ${(\ell,m)=(2,\pm 2)}$ quasinormal modes, and that instead the $(2,\pm 1)$~or~$(2,0)$ quasinormal modes can dominate. Our results are consistent with a ringdown analysis of the LIGO-Virgo gravitational wave signal GW190521, and may also help in understanding phenomenological inspiral-merger-ringdown waveform model systematics. |
1307.1914 | Paul McGrath | Richard J. Epp, Robert B. Mann and Paul L. McGrath | On the Existence and Utility of Rigid Quasilocal Frames | 21 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The notion of a rigid quasilocal frame (RQF) provides a geometrically natural
way to define a system in general relativity, and a new way to analyze the
problem of motion. An RQF is defined as a two-parameter family of timelike
worldlines comprising the boundary (topologically R x S^2) of the history of a
finite spatial volume, with the rigidity conditions that the congruence of
worldlines be expansion- and shear-free. In other words, the size and shape of
the system do not change. In previous work, such systems in Minkowski space
were shown to admit precisely the same six degrees of freedom of rigid body
motion that we are familiar with in Newtonian space-time, without any
constraints, circumventing a century-old theorem due to Herglotz and Noether.
This is a consequence of the fact that a two-sphere of any shape always admits
precisely six conformal Killing vector fields, which generate an action of the
Lorentz group on the sphere. Here we review the previous work in flat spacetime
and extend it in three directions: (1) Using a Fermi normal coordinates
approach, we explicitly construct, to the first few orders in powers of areal
radius, the general solution to the RQF rigidity equations in a generic curved
spacetime, and show that the resulting RQFs possess exactly the same six
motional degrees of freedom as in flat spacetime; (2) We discuss how RQFs
provide a natural context in which to understand the flow of energy, momentum
and angular momentum into and out of a system; in particular, we derive a
simple, exact expression for the flux of gravitational energy (a gravitational
analogue of the Poynting vector) in terms of operationally-defined geometrical
quantities on the boundary; (3) We use this new gravitational (or
"geometrical") energy flux to resolve another apparent paradox, this one
involving electromagnetism in flat spacetime, which we discovered in the course
of this work.
| [
{
"created": "Sun, 7 Jul 2013 20:56:26 GMT",
"version": "v1"
}
] | 2013-07-09 | [
[
"Epp",
"Richard J.",
""
],
[
"Mann",
"Robert B.",
""
],
[
"McGrath",
"Paul L.",
""
]
] | The notion of a rigid quasilocal frame (RQF) provides a geometrically natural way to define a system in general relativity, and a new way to analyze the problem of motion. An RQF is defined as a two-parameter family of timelike worldlines comprising the boundary (topologically R x S^2) of the history of a finite spatial volume, with the rigidity conditions that the congruence of worldlines be expansion- and shear-free. In other words, the size and shape of the system do not change. In previous work, such systems in Minkowski space were shown to admit precisely the same six degrees of freedom of rigid body motion that we are familiar with in Newtonian space-time, without any constraints, circumventing a century-old theorem due to Herglotz and Noether. This is a consequence of the fact that a two-sphere of any shape always admits precisely six conformal Killing vector fields, which generate an action of the Lorentz group on the sphere. Here we review the previous work in flat spacetime and extend it in three directions: (1) Using a Fermi normal coordinates approach, we explicitly construct, to the first few orders in powers of areal radius, the general solution to the RQF rigidity equations in a generic curved spacetime, and show that the resulting RQFs possess exactly the same six motional degrees of freedom as in flat spacetime; (2) We discuss how RQFs provide a natural context in which to understand the flow of energy, momentum and angular momentum into and out of a system; in particular, we derive a simple, exact expression for the flux of gravitational energy (a gravitational analogue of the Poynting vector) in terms of operationally-defined geometrical quantities on the boundary; (3) We use this new gravitational (or "geometrical") energy flux to resolve another apparent paradox, this one involving electromagnetism in flat spacetime, which we discovered in the course of this work. |
0905.3053 | Cenalo Vaz | Cenalo Vaz | Signatures of an Emergent Gravity from Black Hole Entropy | Fifth prize at the 2009 Gravity Research Foundation Awards for Essays
on Gravitation. 5 pages, no figures | Gen.Rel.Grav.41:2307-2311,2009 | 10.1007/s10714-009-0848-0 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The existence of a thermodynamic description of horizons indicates that
spacetime has a microstructure. While the "fundamental" degrees of freedom
remain elusive, quantizing Einstein's gravity provides some clues about their
properties. A quantum AdS black hole possesses an equispaced mass spectrum,
independent of Newton's constant, $G$, when its horizon radius is large
compared to the AdS length. Moreover, the black hole's thermodynamics in this
limit is inextricably connected with its thermodynamics in the opposite
(Schwarzschild) limit by a duality of the Bose partition function. $G$, absent
in the mass spectrum, reemerges in the thermodynamic description through the
Schwarzschild limit, which should be viewed as a natural "ground state". It
seems that the Hawking-Page phase transition separates fundamental,
"particle-like" degrees of freedom from effective, "geometric" ones.
| [
{
"created": "Tue, 19 May 2009 10:07:38 GMT",
"version": "v1"
}
] | 2009-09-28 | [
[
"Vaz",
"Cenalo",
""
]
] | The existence of a thermodynamic description of horizons indicates that spacetime has a microstructure. While the "fundamental" degrees of freedom remain elusive, quantizing Einstein's gravity provides some clues about their properties. A quantum AdS black hole possesses an equispaced mass spectrum, independent of Newton's constant, $G$, when its horizon radius is large compared to the AdS length. Moreover, the black hole's thermodynamics in this limit is inextricably connected with its thermodynamics in the opposite (Schwarzschild) limit by a duality of the Bose partition function. $G$, absent in the mass spectrum, reemerges in the thermodynamic description through the Schwarzschild limit, which should be viewed as a natural "ground state". It seems that the Hawking-Page phase transition separates fundamental, "particle-like" degrees of freedom from effective, "geometric" ones. |
2301.13625 | Alexander Quintero Velez | Camilo Arias Abad, Alexander Quintero Velez and Juan Diego Velez
Caicedo | Relativity | Comments are most welcome! | null | null | null | gr-qc math-ph math.DG math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | These lectures notes contain an introduction to General Relativity. They are
addressed to a general mathematical audience with no specific background in
physics. The goal is to motivate and explain Einstein's theory of gravity and
discuss some of the fundamental examples.
| [
{
"created": "Sun, 29 Jan 2023 19:41:31 GMT",
"version": "v1"
}
] | 2023-02-01 | [
[
"Abad",
"Camilo Arias",
""
],
[
"Velez",
"Alexander Quintero",
""
],
[
"Caicedo",
"Juan Diego Velez",
""
]
] | These lectures notes contain an introduction to General Relativity. They are addressed to a general mathematical audience with no specific background in physics. The goal is to motivate and explain Einstein's theory of gravity and discuss some of the fundamental examples. |
2207.10808 | David Shlivko | David Shlivko | Kinetically-driven ekpyrosis | 10 pages, 4 figures, accepted for publication | Physical Review D, 106(4), 043508 (2022) | 10.1103/PhysRevD.106.043508 | null | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by-nc-sa/4.0/ | We explore the possibility of a scalar field driving ekpyrotic contraction
through a non-canonical kinetic energy density rather than a negative
potential. We find that this kinetically-driven ekpyrosis ("k-ekpyrosis") can
be achieved in a variety of models, including scalar field theories with
power-law, polynomial, or DBI-like kinetic terms in the action. Of these
examples, the ekpyrotic phase is best sustained in power-law models, which can
generate large and constant equation-of-state parameters, followed by DBI-like
models, which can exhibit dynamical attractors toward similarly large equations
of state. We show that for a broad class of theories including these examples,
phases of k-ekpyrosis are accompanied by preceding or concurrent phases of
superluminality.
| [
{
"created": "Thu, 21 Jul 2022 23:50:37 GMT",
"version": "v1"
},
{
"created": "Tue, 9 Aug 2022 23:07:28 GMT",
"version": "v2"
}
] | 2022-08-11 | [
[
"Shlivko",
"David",
""
]
] | We explore the possibility of a scalar field driving ekpyrotic contraction through a non-canonical kinetic energy density rather than a negative potential. We find that this kinetically-driven ekpyrosis ("k-ekpyrosis") can be achieved in a variety of models, including scalar field theories with power-law, polynomial, or DBI-like kinetic terms in the action. Of these examples, the ekpyrotic phase is best sustained in power-law models, which can generate large and constant equation-of-state parameters, followed by DBI-like models, which can exhibit dynamical attractors toward similarly large equations of state. We show that for a broad class of theories including these examples, phases of k-ekpyrosis are accompanied by preceding or concurrent phases of superluminality. |
1501.03698 | Niccol\'o Loret | Niccol\'o Loret and Leonardo Barcaroli | Rainbow metric formalism and Relative Locality | appears in Proceedings of the 13th Marcell Grossmann meeting on
General Relativity, World Scientific, Singapore, (2014) | null | 10.1142/9789814623995_0141 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/3.0/ | This proceeding is based on a talk prepared for the XIII Marcell Grossmann
meeting. We summarise some results of work in progress in collaboration with
Giovanni Amelino-Camelia about momentum dependent (Rainbow) metrics in a
Relative Locality framework and we show that this formalism is equivalent to
the Hamiltonian formalization of Relative Locality obtained in arXiv:1102.4637.
| [
{
"created": "Thu, 15 Jan 2015 14:44:11 GMT",
"version": "v1"
}
] | 2015-06-23 | [
[
"Loret",
"Niccoló",
""
],
[
"Barcaroli",
"Leonardo",
""
]
] | This proceeding is based on a talk prepared for the XIII Marcell Grossmann meeting. We summarise some results of work in progress in collaboration with Giovanni Amelino-Camelia about momentum dependent (Rainbow) metrics in a Relative Locality framework and we show that this formalism is equivalent to the Hamiltonian formalization of Relative Locality obtained in arXiv:1102.4637. |
gr-qc/0510120 | Bjorn Garbrecht | Bjorn Garbrecht and Tomislav Prokopec | Lamb Shift of Unruh Detector Levels | 20 pages | Class.Quant.Grav. 23 (2006) 3917-3934 | 10.1088/0264-9381/23/11/015 | SPIN-05/25, ITP-UU-05/31 | gr-qc | null | We argue that the energy levels of an Unruh detector experience an effect
similar to the Lamb shift in Quantum Electrodynamics. As a consequence, the
spectrum of energy levels in a curved background is different from that in flat
space. As examples, we consider a detector in an expanding Universe and in
Rindler space, and for the latter case we suggest a new expression for the
local virtual energy density seen by an accelerated observer. In the
ultraviolet domain, that is when the space between the energy levels is larger
than the Hubble rate or the acceleration of the detector, the Lamb shift
quantitatively dominates over the thermal response rate.
| [
{
"created": "Fri, 28 Oct 2005 17:27:15 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Garbrecht",
"Bjorn",
""
],
[
"Prokopec",
"Tomislav",
""
]
] | We argue that the energy levels of an Unruh detector experience an effect similar to the Lamb shift in Quantum Electrodynamics. As a consequence, the spectrum of energy levels in a curved background is different from that in flat space. As examples, we consider a detector in an expanding Universe and in Rindler space, and for the latter case we suggest a new expression for the local virtual energy density seen by an accelerated observer. In the ultraviolet domain, that is when the space between the energy levels is larger than the Hubble rate or the acceleration of the detector, the Lamb shift quantitatively dominates over the thermal response rate. |
gr-qc/9906109 | Esposito Giampiero | Giampiero Esposito and Cosimo Stornaiolo | New Supplementary Conditions for a Non-Linear Field Theory: General
Relativity | 8 pages, plain Tex. Talk prepared for the Conference: "Nonlinearity,
integrability and all that (twenty years after needs '79)". Gallipoli, July 1
- July 10, 1999 | null | 10.1142/9789812817587_0062 | DSF preprint 99/21 | gr-qc | null | The Einstein theory of general relativity provides a peculiar example of
classical field theory ruled by non-linear partial differential equations. A
number of supplementary conditions (more frequently called gauge conditions)
have also been considered in the literature. In the present paper, starting
from the de Donder gauge, which is not conformally invariant but is the
gravitational counterpart of the Lorenz gauge, we consider, led by geometric
structures on vector bundles, a new family of gauges in general relativity,
which involve fifth-order covariant derivatives of metric perturbations. A
review of recent results by the authors is presented: restrictions on the
general form of the metric on the vector bundle of symmetric rank-two tensor
fields over space-time; admissibility of such gauges in the case of linearized
theory about flat Euclidean space; generalization to a suitable class of curved
Riemannian backgrounds, by solving an integral equation. Eventually, the
applications to Euclidean quantum gravity are discussed.
| [
{
"created": "Sat, 26 Jun 1999 14:06:34 GMT",
"version": "v1"
}
] | 2016-11-23 | [
[
"Esposito",
"Giampiero",
""
],
[
"Stornaiolo",
"Cosimo",
""
]
] | The Einstein theory of general relativity provides a peculiar example of classical field theory ruled by non-linear partial differential equations. A number of supplementary conditions (more frequently called gauge conditions) have also been considered in the literature. In the present paper, starting from the de Donder gauge, which is not conformally invariant but is the gravitational counterpart of the Lorenz gauge, we consider, led by geometric structures on vector bundles, a new family of gauges in general relativity, which involve fifth-order covariant derivatives of metric perturbations. A review of recent results by the authors is presented: restrictions on the general form of the metric on the vector bundle of symmetric rank-two tensor fields over space-time; admissibility of such gauges in the case of linearized theory about flat Euclidean space; generalization to a suitable class of curved Riemannian backgrounds, by solving an integral equation. Eventually, the applications to Euclidean quantum gravity are discussed. |
gr-qc/9503004 | Dr. sayan Kar | Sayan Kar | STRINGS IN A WORMHOLE BACKGROUND | 21 pages (Revtex) | Phys.Rev. D52 (1995) 2036-2043 | 10.1103/PhysRevD.52.2036 | IP--BBSR--95/15 | gr-qc | null | Exact solutions of the string equations of motion in a specific Lorentzian
wormhole background are obtained. These include both closed and open string
configurations. Perturbations about some of these configurations are
investigated using the manifestly covariant formalism of Larsen and Frolov.
Finally, the generalized Raychaudhuri equations for the corresponding string
worldsheet deformations are written down and analysed briefly.
| [
{
"created": "Fri, 3 Mar 1995 05:30:31 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Kar",
"Sayan",
""
]
] | Exact solutions of the string equations of motion in a specific Lorentzian wormhole background are obtained. These include both closed and open string configurations. Perturbations about some of these configurations are investigated using the manifestly covariant formalism of Larsen and Frolov. Finally, the generalized Raychaudhuri equations for the corresponding string worldsheet deformations are written down and analysed briefly. |
0808.4116 | Vyacheslav Ivanovich Dokuchaev | V. I. Dokuchaev, S. V. Chernov | Evolution of a vacuum shell in the Friedman-Schwarzschild world | 12 pages, 4 figures | Sov.Phys.JETP 107:203-211,2008 | 10.1134/S1063776108080049 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The method of an effective potential is used to investigate the possible
types of evolution of vacuum shells in the Friedman-Schwarzschild world. Such
shells are assumed to emerge during phase transitions in the early Universe.
The possible global geometries are constructed for the Friedman- Schwarzschild
worlds. Approximate solutions to the equation of motion of a vacuum shell have
been found. The conditions under which the end result of the evolution of the
vacuum shells under consideration is the formation of black holes and wormholes
with baby universes inside have been found. The interior of this world can be a
closed, flat, or open Friedman universe.
| [
{
"created": "Fri, 29 Aug 2008 15:58:54 GMT",
"version": "v1"
}
] | 2009-11-13 | [
[
"Dokuchaev",
"V. I.",
""
],
[
"Chernov",
"S. V.",
""
]
] | The method of an effective potential is used to investigate the possible types of evolution of vacuum shells in the Friedman-Schwarzschild world. Such shells are assumed to emerge during phase transitions in the early Universe. The possible global geometries are constructed for the Friedman- Schwarzschild worlds. Approximate solutions to the equation of motion of a vacuum shell have been found. The conditions under which the end result of the evolution of the vacuum shells under consideration is the formation of black holes and wormholes with baby universes inside have been found. The interior of this world can be a closed, flat, or open Friedman universe. |
gr-qc/0512157 | Shin-ei Tsuneishi | Shin-ei Tsuneishi, Kazuya Watanabe and Tooru Tsuchida | Light propagation and gravitational lensing on the Weyl-like spacetime
in scalar-tensor theories of gravity | 38 pages, 23 figures and 1 table, Typographical errors are corrected.
To appear in Progress of Theoretical Physics | Prog.Theor.Phys. 115 (2006) 487-522 | 10.1143/PTP.115.487 | null | gr-qc astro-ph | null | We study light propagation and gravitational lensing in scalar-tensor
theories of gravity by using a static, axisymmetric exterior solution. The
solution has asymptotic flatness properties and is reduced to Voorhees's one in
the case of a constant scalar field. Our studies are done by using a technique
of the conformal transformation such that their results are independent of
details of scalar-tensor theories. For some specific cases, we analytically
obtain a deflection angle of the light path and find that it can become
negative. The appearance of a negative deflection angle indicates
``reflection'' of a light path, and we investigate under which conditions the
light reflection occurs. As for the optical scalars, the Weyl source-term shows
significantly different properties compared with that in the Schwarzschild
spacetime. We therefore classify a space of the model parameters into four
distinct regions on the basis of the qualitative properties of the Weyl
source-term and find a close relationship between this classification and the
occurrence of the light reflection. We finally solve the null geodesic
equations and the optical scalar equations numerically. We find that a picture
of the thin lens is applicable and give a simple analytic model for the optical
scalars. As for the properties of gravitational lensing, the deflection angle
and the image distortion rate are obtained as functions of the impact
parameter. Again, we find a close relationship between their qualitative
properties and the classification above.
| [
{
"created": "Wed, 28 Dec 2005 14:37:26 GMT",
"version": "v1"
},
{
"created": "Wed, 11 Jan 2006 15:00:26 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Tsuneishi",
"Shin-ei",
""
],
[
"Watanabe",
"Kazuya",
""
],
[
"Tsuchida",
"Tooru",
""
]
] | We study light propagation and gravitational lensing in scalar-tensor theories of gravity by using a static, axisymmetric exterior solution. The solution has asymptotic flatness properties and is reduced to Voorhees's one in the case of a constant scalar field. Our studies are done by using a technique of the conformal transformation such that their results are independent of details of scalar-tensor theories. For some specific cases, we analytically obtain a deflection angle of the light path and find that it can become negative. The appearance of a negative deflection angle indicates ``reflection'' of a light path, and we investigate under which conditions the light reflection occurs. As for the optical scalars, the Weyl source-term shows significantly different properties compared with that in the Schwarzschild spacetime. We therefore classify a space of the model parameters into four distinct regions on the basis of the qualitative properties of the Weyl source-term and find a close relationship between this classification and the occurrence of the light reflection. We finally solve the null geodesic equations and the optical scalar equations numerically. We find that a picture of the thin lens is applicable and give a simple analytic model for the optical scalars. As for the properties of gravitational lensing, the deflection angle and the image distortion rate are obtained as functions of the impact parameter. Again, we find a close relationship between their qualitative properties and the classification above. |
gr-qc/9703031 | null | Brien C. Nolan (Dublin City University) | A Characterisation of Strong Wave Tails in Curved Space-Times | 17 pages, Revtex, to appear in Classical and Quantum Gravity | Class.Quant.Grav. 14 (1997) 1295-1308 | 10.1088/0264-9381/14/5/030 | null | gr-qc | null | A characterisation of when wave tails are strong is proposed. The existence
of a curvature induced tail (i.e. a Green's function term whose support
includes the interior of the light-cone) is commonly understood to cause
backscattering of the field governed by the relevant wave equation. Strong
tails are characterised as those for which the purely radiative part of the
field is backscattered. With this definition, it is shown that electromagnetic
waves in asymptotically flat space-times and fields governed by tail-free
propagation have weak tails, but minimally coupled scalar fields in a
cosmological scenario have strong tails.
| [
{
"created": "Wed, 12 Mar 1997 18:13:31 GMT",
"version": "v1"
}
] | 2009-10-30 | [
[
"Nolan",
"Brien C.",
"",
"Dublin City University"
]
] | A characterisation of when wave tails are strong is proposed. The existence of a curvature induced tail (i.e. a Green's function term whose support includes the interior of the light-cone) is commonly understood to cause backscattering of the field governed by the relevant wave equation. Strong tails are characterised as those for which the purely radiative part of the field is backscattered. With this definition, it is shown that electromagnetic waves in asymptotically flat space-times and fields governed by tail-free propagation have weak tails, but minimally coupled scalar fields in a cosmological scenario have strong tails. |
0705.0740 | Farook Rahaman | F.Rahaman, M.Kalam and S.Chakraborty | Gravitational lensing by stable C-field wormhole | 15 pages, 3 figures. Submitted in Chin.J.phys. after minor revisions,
some references added | Chin.J.Phys.45:518,2007 | null | null | gr-qc | null | It has been recently shown that Hoyle-Narlikar's C-field theory admits
wormhole geometry. We derive the deflection angle of light rays caused by
C-field wormhole in the strong field limit approach of gravitational lensing
theory. The linearized stability of C-field wormhole under spherically
symmetric perturbations about static equilibrium is also explored.
| [
{
"created": "Sat, 5 May 2007 11:18:35 GMT",
"version": "v1"
},
{
"created": "Mon, 4 Jun 2007 09:06:05 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Rahaman",
"F.",
""
],
[
"Kalam",
"M.",
""
],
[
"Chakraborty",
"S.",
""
]
] | It has been recently shown that Hoyle-Narlikar's C-field theory admits wormhole geometry. We derive the deflection angle of light rays caused by C-field wormhole in the strong field limit approach of gravitational lensing theory. The linearized stability of C-field wormhole under spherically symmetric perturbations about static equilibrium is also explored. |
gr-qc/0601019 | Yasushi Mino | Yasushi Mino | Adiabatic Expansion for Metric Perturbation and the condition to solve
the Gauge Problem for Gravitational Radiation Reaction Problem | accepted by Progress of Theoretical Physics | Prog.Theor.Phys. 115 (2006) 43-61 | 10.1143/PTP.115.43 | null | gr-qc | null | We examine the adiabatic approximation in the study of a relativistic
two-body problem with the gravitational radiation reaction. We recently pointed
out that the usual metric perturbation scheme using a perturbation of the
stress-energy tensor may not be appropriate for study of the dissipative
dynamics of the bodies due to the radiation reaction.
We recently proposed a possible approach to solve this problem with a linear
black hole perturbation. This paper proposes a non-linear generalization of
that method for a general application of this problem. We show that, under a
specific gauge condition, the method actually allows us to avoid the gauge
problem.
| [
{
"created": "Thu, 5 Jan 2006 08:26:56 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Mino",
"Yasushi",
""
]
] | We examine the adiabatic approximation in the study of a relativistic two-body problem with the gravitational radiation reaction. We recently pointed out that the usual metric perturbation scheme using a perturbation of the stress-energy tensor may not be appropriate for study of the dissipative dynamics of the bodies due to the radiation reaction. We recently proposed a possible approach to solve this problem with a linear black hole perturbation. This paper proposes a non-linear generalization of that method for a general application of this problem. We show that, under a specific gauge condition, the method actually allows us to avoid the gauge problem. |
2112.06301 | Marek Li\v{s}ka | Ana Alonso-Serrano, Marek Li\v{s}ka | Thermodynamics of spacetime and unimodular gravity | 19 pages, 2 figures. Review prepared for a Special Issue of the
International Journal of Geometric Methods in Modern Physics dedicated to the
conference Geometric Foundations of Gravity 2021. Version accepted by IJGMMP | null | 10.1142/S0219887822300021 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this review we discuss emergence of unimodular gravity (or, more
precisely, Weyl transverse gravity) from thermodynamics of spacetime. By
analyzing three different ways to obtain gravitational equations of motion by
thermodynamic arguments, we show that the results point to unimodular rather
than fully diffeomorphism invariant theories and that this is true even for
modified gravity. The unimodular character of dynamics is especially evident
from the status of cosmological constant and energy-momentum conservation.
| [
{
"created": "Sun, 12 Dec 2021 18:48:01 GMT",
"version": "v1"
},
{
"created": "Mon, 18 Apr 2022 09:42:57 GMT",
"version": "v2"
}
] | 2022-04-19 | [
[
"Alonso-Serrano",
"Ana",
""
],
[
"Liška",
"Marek",
""
]
] | In this review we discuss emergence of unimodular gravity (or, more precisely, Weyl transverse gravity) from thermodynamics of spacetime. By analyzing three different ways to obtain gravitational equations of motion by thermodynamic arguments, we show that the results point to unimodular rather than fully diffeomorphism invariant theories and that this is true even for modified gravity. The unimodular character of dynamics is especially evident from the status of cosmological constant and energy-momentum conservation. |
0707.4455 | Gilberto Medeiros Kremer | Luis P. Chimento, Fernando P. Devecchi, Monica Forte and Gilberto M.
Kremer | Phantom cosmologies and fermions | 5 pages, version which was accepted for publication in CQG | Class.Quant.Grav.25:085007,2008 | 10.1088/0264-9381/25/8/085007 | null | gr-qc | null | Form invariance transformations can be used for constructing phantom
cosmologies starting with conventional cosmological models. In this work we
reconsider the scalar field case and extend the discussion to fermionic fields,
where the "phantomization" process exhibits a new class of possible accelerated
regimes. As an application we analyze the cosmological constant group for a
fermionic seed fluid.
| [
{
"created": "Mon, 30 Jul 2007 17:48:33 GMT",
"version": "v1"
},
{
"created": "Wed, 5 Mar 2008 07:13:11 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Chimento",
"Luis P.",
""
],
[
"Devecchi",
"Fernando P.",
""
],
[
"Forte",
"Monica",
""
],
[
"Kremer",
"Gilberto M.",
""
]
] | Form invariance transformations can be used for constructing phantom cosmologies starting with conventional cosmological models. In this work we reconsider the scalar field case and extend the discussion to fermionic fields, where the "phantomization" process exhibits a new class of possible accelerated regimes. As an application we analyze the cosmological constant group for a fermionic seed fluid. |
2102.02232 | Alireza Allahyari | Alireza Allahyari, Lijing Shao | Testing No-Hair Theorem by Quasi-Periodic Oscillations: the quadrupole
of GRO J1655$-$40 | 20 pages, 8 figures, 1 table, improved version, accepted for
publication in JCAP | JCAP10(2021)003 | 10.1088/1475-7516/2021/10/003 | null | gr-qc astro-ph.CO astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | We perform an observational test of no-hair theorem using quasi-periodic
oscillations within the relativistic precession model. Two well motivated
metrics we apply are Kerr-Q and Hartle-Thorne metrics in which the quadrupole
is the parameter that possibly encodes deviations from the Kerr black hole. The
expressions for the quasi-periodic frequencies are derived before comparing the
models with the observation. We encounter a degeneracy in constraining spin and
quadrupole parameters that makes it difficult to measure their values. In
particular, we here propose a novel test of no-hair theorem by adapting the
Hartle-Thorne metric. It turns out that a Kerr black hole is a good description
of the central object in GRO J1655$-$40 given the present observational
precisions.
| [
{
"created": "Wed, 3 Feb 2021 19:01:00 GMT",
"version": "v1"
},
{
"created": "Tue, 12 Oct 2021 09:16:58 GMT",
"version": "v2"
}
] | 2021-10-13 | [
[
"Allahyari",
"Alireza",
""
],
[
"Shao",
"Lijing",
""
]
] | We perform an observational test of no-hair theorem using quasi-periodic oscillations within the relativistic precession model. Two well motivated metrics we apply are Kerr-Q and Hartle-Thorne metrics in which the quadrupole is the parameter that possibly encodes deviations from the Kerr black hole. The expressions for the quasi-periodic frequencies are derived before comparing the models with the observation. We encounter a degeneracy in constraining spin and quadrupole parameters that makes it difficult to measure their values. In particular, we here propose a novel test of no-hair theorem by adapting the Hartle-Thorne metric. It turns out that a Kerr black hole is a good description of the central object in GRO J1655$-$40 given the present observational precisions. |
2307.07431 | Pablo Antonio Cano Molina-Ni\~nirola | Pablo A. Cano, Kwinten Fransen, Thomas Hertog, Simon Maenaut | Quasinormal modes of rotating black holes in higher-derivative gravity | v2: version accepted in PRD. Contains a new plot for the (330) modes
and we added a new comment on the accuracy of our results. We make it clear
that they are accurate enough to allow for precision tests of
higher-derivative corrections in future experiments | null | null | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compute the spectrum of linearized gravitational excitations of black
holes with substantial angular momentum in the presence of higher-derivative
corrections to general relativity. We do so perturbatively to leading order in
the higher-derivative couplings and up to order fourteen in the black hole
angular momentum. This allows us to accurately predict quasinormal mode
frequencies of black holes with spins up to about $70\%$ of the extremal value.
For some higher-derivative corrections, we find that sizable rotation enhances
the frequency shifts by almost an order of magnitude relative to the static
case.
| [
{
"created": "Fri, 14 Jul 2023 15:53:38 GMT",
"version": "v1"
},
{
"created": "Sun, 12 Nov 2023 12:14:24 GMT",
"version": "v2"
}
] | 2023-11-14 | [
[
"Cano",
"Pablo A.",
""
],
[
"Fransen",
"Kwinten",
""
],
[
"Hertog",
"Thomas",
""
],
[
"Maenaut",
"Simon",
""
]
] | We compute the spectrum of linearized gravitational excitations of black holes with substantial angular momentum in the presence of higher-derivative corrections to general relativity. We do so perturbatively to leading order in the higher-derivative couplings and up to order fourteen in the black hole angular momentum. This allows us to accurately predict quasinormal mode frequencies of black holes with spins up to about $70\%$ of the extremal value. For some higher-derivative corrections, we find that sizable rotation enhances the frequency shifts by almost an order of magnitude relative to the static case. |
1611.08433 | Victor Hugo Cardenas | Cuauhtemoc Campuzano, Victor H Cardenas and Ramon Herrera | Mimicking the LCDM model with Stealths | 5 pages, 4 figures | null | 10.1140/epjc/s10052-016-4546-2 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a new cosmological model that mimics the Lambda Cold Dark Matter
by using a stealth field. This kind of field is characterized as not coupling
directly to gravity; however, it is connected to the underlying matter content
of the universe model. As is known, stealth fields do not back-react on the
space-time; however, their mimicry skills show how this field and its
self-interaction potential determines the cosmic evolution. We show the study
of the simplest model that can be developed with the stealth field.
| [
{
"created": "Fri, 25 Nov 2016 12:11:20 GMT",
"version": "v1"
}
] | 2017-02-01 | [
[
"Campuzano",
"Cuauhtemoc",
""
],
[
"Cardenas",
"Victor H",
""
],
[
"Herrera",
"Ramon",
""
]
] | We present a new cosmological model that mimics the Lambda Cold Dark Matter by using a stealth field. This kind of field is characterized as not coupling directly to gravity; however, it is connected to the underlying matter content of the universe model. As is known, stealth fields do not back-react on the space-time; however, their mimicry skills show how this field and its self-interaction potential determines the cosmic evolution. We show the study of the simplest model that can be developed with the stealth field. |
gr-qc/0012031 | Diego F. Torres | Diego F. Torres, S. Capozziello and G. Lambiase | Supermassive boson stars: prospects for observational detection | Short paper to be published in the Proceedings of the MG 9 Meeting.
July 2000, Rome | null | null | null | gr-qc | null | In a recent work (Torres, Capozziello and Lambiase, Physical Review D62,
104012 (2000)), it was shown that a supermassive boson star could provide an
alternative model for the galactic center, usually assumed as a black hole.
Here we comment on some of the possibilities to actually detect this object,
and how can it be distinguished from the standard and other alternative models.
| [
{
"created": "Thu, 7 Dec 2000 14:10:55 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Torres",
"Diego F.",
""
],
[
"Capozziello",
"S.",
""
],
[
"Lambiase",
"G.",
""
]
] | In a recent work (Torres, Capozziello and Lambiase, Physical Review D62, 104012 (2000)), it was shown that a supermassive boson star could provide an alternative model for the galactic center, usually assumed as a black hole. Here we comment on some of the possibilities to actually detect this object, and how can it be distinguished from the standard and other alternative models. |
1503.02622 | Andr\'e Gro{\ss}ardt | Andr\'e Gro{\ss}ardt | Approximations for the free evolution of self-gravitating quantum
particles | Final draft accepted for publication by Phys. Rev. A | Phys. Rev. A 94, 022101 (2016) | 10.1103/PhysRevA.94.022101 | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The evolution of the centre-of-mass wave-function for a mesoscopic particle
according to the Schr\"odinger-Newton equation can be approximated by a
harmonic potential, if the wave-function is narrow compared to the size of the
particle. It was noticed by Colin et al. [Phys. Rev. A, 93, 062102 (2016)]
that, in the regime where self-gravitational effects are weak, intermediate and
wider wave-functions may be approximated by a harmonic potential as well, but
with a width dependent coupling, leading to a time evolution that is determined
only by a differential equation for the width of a Gaussian wave-function as a
single parameter. Such an approximation results in considerably less
computational effort in order to predict the self-gravitational effects on the
wave-function dynamics. Here, we provide an alternative approach to this kind
of approximation, including a rigorous derivation of the equations of motion
for an initially Gaussian wave packet, under the assumption that its shape is
conserved. Our result deviates to some degree from the result by Colin et al.,
specifically in the limit of wide wave-functions.
| [
{
"created": "Mon, 9 Mar 2015 19:07:22 GMT",
"version": "v1"
},
{
"created": "Sat, 18 Jun 2016 13:53:00 GMT",
"version": "v2"
},
{
"created": "Mon, 1 Aug 2016 15:54:25 GMT",
"version": "v3"
}
] | 2016-08-02 | [
[
"Großardt",
"André",
""
]
] | The evolution of the centre-of-mass wave-function for a mesoscopic particle according to the Schr\"odinger-Newton equation can be approximated by a harmonic potential, if the wave-function is narrow compared to the size of the particle. It was noticed by Colin et al. [Phys. Rev. A, 93, 062102 (2016)] that, in the regime where self-gravitational effects are weak, intermediate and wider wave-functions may be approximated by a harmonic potential as well, but with a width dependent coupling, leading to a time evolution that is determined only by a differential equation for the width of a Gaussian wave-function as a single parameter. Such an approximation results in considerably less computational effort in order to predict the self-gravitational effects on the wave-function dynamics. Here, we provide an alternative approach to this kind of approximation, including a rigorous derivation of the equations of motion for an initially Gaussian wave packet, under the assumption that its shape is conserved. Our result deviates to some degree from the result by Colin et al., specifically in the limit of wide wave-functions. |
1401.0785 | Jie-Xiong Mo | Jie-Xiong Mo, Wen-Biao Liu | P-V Criticality of Topological Black Holes in Lovelock-Born-Infeld
Gravity | 13 pages, 7 figures | Eur. Phys. J. C (2014) 74:2836 | 10.1140/epjc/s10052-014-2836-0 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | To understand the effect of third order Lovelock gravity, $P-V$ criticality
of topological AdS black holes in Lovelock-Born-Infeld gravity is investigated.
The thermodynamics is further explored with some more extensions and details
than the former literature. A detailed analysis of the limit case
$\beta\rightarrow\infty$ is performed for the seven-dimensional black holes. It
is shown that for the spherical topology, $P-V$ criticality exists for both the
uncharged and charged cases. Our results demonstrate again that the charge is
not the indispensable condition of $P-V$ criticality. It may be attributed to
the effect of higher derivative terms of curvature because similar phenomenon
was also found for Gauss-Bonnet black holes. For $k=0$, there would be no $P-V$
criticality. Interesting findings occur in the case $k=-1$, in which positive
solutions of critical points are found for both the uncharged and charged
cases. However, the $P-v$ diagram is quite strange. To check whether these
findings are physical, we give the analysis on the non-negative definiteness
condition of entropy. It is shown that for any nontrivial value of $\alpha$,
the entropy is always positive for any specific volume $v$. Since no $P-V$
criticality exists for $k=-1$ in Einstein gravity and Gauss-Bonnet gravity, we
can relate our findings with the peculiar property of third order Lovelock
gravity. The entropy in third order Lovelock gravity consists of extra terms
which is absent in the Gauss-Bonnet black holes, which makes the critical
points satisfy the constraint of non-negative definiteness condition of
entropy. We also check the Gibbs free energy graph and the "swallow tail"
behavior can be observed. Moreover, the effect of nonlinear electrodynamics is
also included in our research.
| [
{
"created": "Sat, 4 Jan 2014 07:16:47 GMT",
"version": "v1"
}
] | 2014-04-09 | [
[
"Mo",
"Jie-Xiong",
""
],
[
"Liu",
"Wen-Biao",
""
]
] | To understand the effect of third order Lovelock gravity, $P-V$ criticality of topological AdS black holes in Lovelock-Born-Infeld gravity is investigated. The thermodynamics is further explored with some more extensions and details than the former literature. A detailed analysis of the limit case $\beta\rightarrow\infty$ is performed for the seven-dimensional black holes. It is shown that for the spherical topology, $P-V$ criticality exists for both the uncharged and charged cases. Our results demonstrate again that the charge is not the indispensable condition of $P-V$ criticality. It may be attributed to the effect of higher derivative terms of curvature because similar phenomenon was also found for Gauss-Bonnet black holes. For $k=0$, there would be no $P-V$ criticality. Interesting findings occur in the case $k=-1$, in which positive solutions of critical points are found for both the uncharged and charged cases. However, the $P-v$ diagram is quite strange. To check whether these findings are physical, we give the analysis on the non-negative definiteness condition of entropy. It is shown that for any nontrivial value of $\alpha$, the entropy is always positive for any specific volume $v$. Since no $P-V$ criticality exists for $k=-1$ in Einstein gravity and Gauss-Bonnet gravity, we can relate our findings with the peculiar property of third order Lovelock gravity. The entropy in third order Lovelock gravity consists of extra terms which is absent in the Gauss-Bonnet black holes, which makes the critical points satisfy the constraint of non-negative definiteness condition of entropy. We also check the Gibbs free energy graph and the "swallow tail" behavior can be observed. Moreover, the effect of nonlinear electrodynamics is also included in our research. |
1911.01950 | Betti Hartmann | Yves Brihaye, Betti Hartmann, Nath\'alia Pio Aprile, Jon Urrestilla | Scalarization of asymptotically Anti-de Sitter black holes with
applications to holographic phase transitions | v2: discussion on Fefferman-Graham construction added; discussion on
applications to condensed matter systems added; matches version accepted for
publication in Phys. Rev.D | Phys. Rev. D 101, 124016 (2020) | 10.1103/PhysRevD.101.124016 | null | gr-qc hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the spontaneous scalarization of spherically symmetric, static and
asymptotically Anti-de Sitter (aAdS) black holes in a scalar-tensor gravity
model with non-mininal coupling of the form $\phi^2\left(\alpha{\cal R} +
\gamma {\cal G}\right)$, where $\alpha$ and $\gamma$ are constants, while
${\cal R}$ and ${\cal G}$ are the Ricci scalar and Gauss-Bonnet term,
respectively. Since these terms act as an effective ``mass'' for the scalar
field, non-trivial values of the scalar field in the black hole space-time are
possible for {\it a priori} vanishing scalar field mass. In particular, we
demonstrate that the scalarization of an aAdS black hole requires the curvature
invariant $-\left(\alpha{\cal R} + \gamma {\cal G}\right)$ to drop below the
Breitenlohner-Freedman bound close to the black hole horizon, while it
asymptotes to a value well above the bound. The dimension of the dual operator
on the AdS boundary depends on the parameters $\alpha$ and $\gamma$ and we
demonstrate that -- for fixed operator dimension -- the expectation value of
this dual operator increases with decreasing temperature of the black hole,
i.e. of the dual field theory. When taking backreaction of the space-time into
account, we find that the scalarization of the black hole is the dual
description of a phase transition in a strongly coupled quantum system, i.e.
corresponds to a holographic phase transition. A possible application are
liquid-gas quantum phase transitions, e.g. in $^4$He. Finally, we demonstrate
that extremal black holes with $AdS_2\times S^2$ near-horizon geometry {\it
cannot support regular scalar fields on the horizon} in the scalar-tensor model
studied here.
| [
{
"created": "Tue, 5 Nov 2019 17:20:53 GMT",
"version": "v1"
},
{
"created": "Tue, 12 May 2020 09:06:01 GMT",
"version": "v2"
}
] | 2020-07-01 | [
[
"Brihaye",
"Yves",
""
],
[
"Hartmann",
"Betti",
""
],
[
"Aprile",
"Nathália Pio",
""
],
[
"Urrestilla",
"Jon",
""
]
] | We study the spontaneous scalarization of spherically symmetric, static and asymptotically Anti-de Sitter (aAdS) black holes in a scalar-tensor gravity model with non-mininal coupling of the form $\phi^2\left(\alpha{\cal R} + \gamma {\cal G}\right)$, where $\alpha$ and $\gamma$ are constants, while ${\cal R}$ and ${\cal G}$ are the Ricci scalar and Gauss-Bonnet term, respectively. Since these terms act as an effective ``mass'' for the scalar field, non-trivial values of the scalar field in the black hole space-time are possible for {\it a priori} vanishing scalar field mass. In particular, we demonstrate that the scalarization of an aAdS black hole requires the curvature invariant $-\left(\alpha{\cal R} + \gamma {\cal G}\right)$ to drop below the Breitenlohner-Freedman bound close to the black hole horizon, while it asymptotes to a value well above the bound. The dimension of the dual operator on the AdS boundary depends on the parameters $\alpha$ and $\gamma$ and we demonstrate that -- for fixed operator dimension -- the expectation value of this dual operator increases with decreasing temperature of the black hole, i.e. of the dual field theory. When taking backreaction of the space-time into account, we find that the scalarization of the black hole is the dual description of a phase transition in a strongly coupled quantum system, i.e. corresponds to a holographic phase transition. A possible application are liquid-gas quantum phase transitions, e.g. in $^4$He. Finally, we demonstrate that extremal black holes with $AdS_2\times S^2$ near-horizon geometry {\it cannot support regular scalar fields on the horizon} in the scalar-tensor model studied here. |
2009.08467 | Rossella Gamba | Rossella Gamba, Matteo Breschi, Sebastiano Bernuzzi, Michalis Agathos
and Alessandro Nagar | Waveform systematics in the gravitational-wave inference of tidal
parameters and equation of state from binary neutron star signals | null | Phys. Rev. D 103, 124015 (2021) | 10.1103/PhysRevD.103.124015 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational-wave signals from binary neutron star coalescences carry
information about the star's equation of state in their tidal signatures. A
major issue in the inference of the tidal parameters (or directly of the
equation of state) is the systematic error introduced by the waveform
approximants. We use a bottom-up approach based on gauge-invariant phase
analysis and the Fisher information matrix to investigate waveform systematics
and help identifying biases in parameter estimation. A mock analysis of 15
different binaries indicates that systematics in current waveform models
dominate over statistical errors at signal-to-noise ratio (SNR) ${\gtrsim} 80$.
This implies biases in the inference of the reduced tidal parameter that are
are larger than the statistical $90\%$ credible-intervals. For example, while
the neutron-star radius could be constrained at ${\sim} 5\%$ level at SNR 80,
systematics can be at the ${\sim} 10\%$ level. We apply our approach to
GW170817 (SNR ${\sim}30$) and confirm that no significant systematic effects
are present. Using an optimal frequency range for the analysis, we estimate a
neutron-star radius of $12.5^{+1.1}_{-1.8}\,$km. The latter is consistent with
an electromagnetic-informed prior and the recent NICER measurement. Exploring
SNR ${\gtrsim}100$ in view of third-generation detectors, we find that all the
current waveform models lead to differences of at least 1-sigma in the
inference of the reduced tidal parameter (for any value of the latter). We
conclude that current waveform models, including those from numerical
relativity, are insufficient to infer the equation of state in the loudest (and
potentially most informative) events that will be observed by advanced and
third generation detectors.
| [
{
"created": "Thu, 17 Sep 2020 18:00:03 GMT",
"version": "v1"
}
] | 2021-06-16 | [
[
"Gamba",
"Rossella",
""
],
[
"Breschi",
"Matteo",
""
],
[
"Bernuzzi",
"Sebastiano",
""
],
[
"Agathos",
"Michalis",
""
],
[
"Nagar",
"Alessandro",
""
]
] | Gravitational-wave signals from binary neutron star coalescences carry information about the star's equation of state in their tidal signatures. A major issue in the inference of the tidal parameters (or directly of the equation of state) is the systematic error introduced by the waveform approximants. We use a bottom-up approach based on gauge-invariant phase analysis and the Fisher information matrix to investigate waveform systematics and help identifying biases in parameter estimation. A mock analysis of 15 different binaries indicates that systematics in current waveform models dominate over statistical errors at signal-to-noise ratio (SNR) ${\gtrsim} 80$. This implies biases in the inference of the reduced tidal parameter that are are larger than the statistical $90\%$ credible-intervals. For example, while the neutron-star radius could be constrained at ${\sim} 5\%$ level at SNR 80, systematics can be at the ${\sim} 10\%$ level. We apply our approach to GW170817 (SNR ${\sim}30$) and confirm that no significant systematic effects are present. Using an optimal frequency range for the analysis, we estimate a neutron-star radius of $12.5^{+1.1}_{-1.8}\,$km. The latter is consistent with an electromagnetic-informed prior and the recent NICER measurement. Exploring SNR ${\gtrsim}100$ in view of third-generation detectors, we find that all the current waveform models lead to differences of at least 1-sigma in the inference of the reduced tidal parameter (for any value of the latter). We conclude that current waveform models, including those from numerical relativity, are insufficient to infer the equation of state in the loudest (and potentially most informative) events that will be observed by advanced and third generation detectors. |
1510.03858 | Lee Smolin | Lee Smolin | The thermodynamics of quantum spacetime histories | Latex 39 pages, 6 figures | Phys. Rev. D 96, 104042 (2017) | 10.1103/PhysRevD.96.104042 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that the simplicity constraints, which define the dynamics of spin
foam models, imply, and are implied by, the first law of thermodynamics, when
the latter is applied to causal diamonds in the quantum spacetime. This result
reveals an intimate connection between the holographic nature of gravity, as
reflected by the Bekenstein entropy, and the fact that general relativity and
other gravitational theories can be understood as constrained topological field
theories.
To state and derive this correspondence we describe causal diamonds in the
causal structure of spin foam histories and generalize arguments given for the
near horizon region of black holes by Frodden, Gosh and Perez and Bianchi. This
allows us to apply a recent argument of Jacobson to show that if a spin foam
history has a semiclassical limit described in terms of a smooth metric
geometry, that geometry satisfies the Einstein equations.
These results suggest also a proposal for a quantum equivalence principle.
| [
{
"created": "Tue, 13 Oct 2015 20:12:48 GMT",
"version": "v1"
}
] | 2017-11-29 | [
[
"Smolin",
"Lee",
""
]
] | We show that the simplicity constraints, which define the dynamics of spin foam models, imply, and are implied by, the first law of thermodynamics, when the latter is applied to causal diamonds in the quantum spacetime. This result reveals an intimate connection between the holographic nature of gravity, as reflected by the Bekenstein entropy, and the fact that general relativity and other gravitational theories can be understood as constrained topological field theories. To state and derive this correspondence we describe causal diamonds in the causal structure of spin foam histories and generalize arguments given for the near horizon region of black holes by Frodden, Gosh and Perez and Bianchi. This allows us to apply a recent argument of Jacobson to show that if a spin foam history has a semiclassical limit described in terms of a smooth metric geometry, that geometry satisfies the Einstein equations. These results suggest also a proposal for a quantum equivalence principle. |
0906.1318 | Juhua Chen | Juhua Chen, Yongjiu Wang | Quasinormal Modes of Scalar Field in Five-dimensional Lovelock Black
Hole Spacetime | 12 pages, 6 figures, 2 tables | Chin.Phys.B19:060401,2010 | 10.1088/1674-1056/19/6/060401 | null | gr-qc | http://creativecommons.org/licenses/by/3.0/ | In this paper using the third-order WKB approximation, a numerical method
devised by Schutz, Will and Iyer, we investigate the quasinormal frequencies of
the scalar field in the background of five-dimensional Lovelock black hole. We
find that the ultraviolet correction to Einstein theory in the Lovelock theory
makes the scalar field decay more slowly and makes the scalar field oscillate
more quickly, and the cosmological constant makes the scalar field decay more
slowly and makes the scalar field oscillate more slowly in Lovelock black hole
backgroud. On the other hand we also find that quasinormal frequencies depend
very weakly on the angular quantum number $l$.
| [
{
"created": "Sun, 7 Jun 2009 01:32:36 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Jun 2009 02:28:38 GMT",
"version": "v2"
},
{
"created": "Mon, 22 Jun 2009 07:28:49 GMT",
"version": "v3"
}
] | 2011-03-28 | [
[
"Chen",
"Juhua",
""
],
[
"Wang",
"Yongjiu",
""
]
] | In this paper using the third-order WKB approximation, a numerical method devised by Schutz, Will and Iyer, we investigate the quasinormal frequencies of the scalar field in the background of five-dimensional Lovelock black hole. We find that the ultraviolet correction to Einstein theory in the Lovelock theory makes the scalar field decay more slowly and makes the scalar field oscillate more quickly, and the cosmological constant makes the scalar field decay more slowly and makes the scalar field oscillate more slowly in Lovelock black hole backgroud. On the other hand we also find that quasinormal frequencies depend very weakly on the angular quantum number $l$. |
gr-qc/0205049 | Ali Mostafazadeh | Ali Mostafazadeh | Probability Interpretation for Klein-Gordon Fields and the Hilbert Space
Problem in Quantum Cosmology | 11 pages, references added, slightly revised version | null | null | null | gr-qc hep-th math-ph math.MP quant-ph | null | We give an explicit construction of a positive-definite invariant
inner-product for the Klein-Gordon fields, thus solving the old problem of the
probability interpretation of Klein-Gordon fields without having to restrict to
the subspaces of the positive-frequency solutions. Our method has a much wider
domain of application and may be used to obtain the most general invariant
inner-product on the solution space of a broad class of Klein-Gordon type
evolution equations. We explore its consequences for the solutions of the
Wheeler-DeWitt equation associated with the FRW-massive-real-scalar-field
models.
| [
{
"created": "Mon, 13 May 2002 11:31:51 GMT",
"version": "v1"
},
{
"created": "Fri, 12 Jul 2002 13:58:37 GMT",
"version": "v2"
},
{
"created": "Wed, 4 Dec 2002 14:49:44 GMT",
"version": "v3"
},
{
"created": "Wed, 23 Jul 2003 08:15:15 GMT",
"version": "v4"
}
] | 2007-05-23 | [
[
"Mostafazadeh",
"Ali",
""
]
] | We give an explicit construction of a positive-definite invariant inner-product for the Klein-Gordon fields, thus solving the old problem of the probability interpretation of Klein-Gordon fields without having to restrict to the subspaces of the positive-frequency solutions. Our method has a much wider domain of application and may be used to obtain the most general invariant inner-product on the solution space of a broad class of Klein-Gordon type evolution equations. We explore its consequences for the solutions of the Wheeler-DeWitt equation associated with the FRW-massive-real-scalar-field models. |
gr-qc/9901058 | Dumitru Astefanesei | D. Astefanesei (McGill University), E. Radu (Freiburg University) | On the gravitational field of a point mass in Einstein Universe
background | 9 pages, 1 figure, major changes and much additional material since
original submission in 1999 | null | null | null | gr-qc | null | Some properties of an exact solution due to Vaidya, describing the
gravitational field produced by a point particle in the background of the
static Einstein universe are examined. The maximal analytic extension and the
nature of the singularities of the model are discussed. By using the Euclidean
approach, some quantum aspects are analysed and the thermodynamics of this
spacetime is also discussed.
| [
{
"created": "Thu, 21 Jan 1999 19:56:45 GMT",
"version": "v1"
},
{
"created": "Thu, 6 Dec 2001 22:13:05 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Astefanesei",
"D.",
"",
"McGill University"
],
[
"Radu",
"E.",
"",
"Freiburg University"
]
] | Some properties of an exact solution due to Vaidya, describing the gravitational field produced by a point particle in the background of the static Einstein universe are examined. The maximal analytic extension and the nature of the singularities of the model are discussed. By using the Euclidean approach, some quantum aspects are analysed and the thermodynamics of this spacetime is also discussed. |
gr-qc/9909070 | Sean Hayward | Sean A. Hayward | Gravitational waves, black holes and cosmic strings in cylindrical
symmetry | 10 pages, revtex. Published version with further details | Class.Quant.Grav. 17 (2000) 1749-1764 | 10.1088/0264-9381/17/8/302 | null | gr-qc | null | Gravitational waves in cylindrically symmetric Einstein gravity are described
by an effective energy tensor with the same form as that of a massless Klein-
Gordon field, in terms of a gravitational potential generalizing the Newtonian
potential. Energy-momentum vectors for the gravitational waves and matter are
defined with respect to a canonical flow of time. The combined energy-momentum
is covariantly conserved, the corresponding charge being the modified Thorne
energy. Energy conservation is formulated as the first law expressing the
gradient of the energy as work and energy-supply terms, including the energy
flux of the gravitational waves. Projecting this equation along a trapping
horizon yields a first law of black-hole dynamics containing the expected term
involving area and surface gravity, where the dynamic surface gravity is
defined with respect to the canonical flow of time. A first law for dynamic
cosmic strings also follows. The Einstein equation is written as three wave
equations plus the first law, each with sources determined by the combined
energy tensor of the matter and gravitational waves.
| [
{
"created": "Tue, 21 Sep 1999 18:23:12 GMT",
"version": "v1"
},
{
"created": "Thu, 13 Apr 2000 17:25:29 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Hayward",
"Sean A.",
""
]
] | Gravitational waves in cylindrically symmetric Einstein gravity are described by an effective energy tensor with the same form as that of a massless Klein- Gordon field, in terms of a gravitational potential generalizing the Newtonian potential. Energy-momentum vectors for the gravitational waves and matter are defined with respect to a canonical flow of time. The combined energy-momentum is covariantly conserved, the corresponding charge being the modified Thorne energy. Energy conservation is formulated as the first law expressing the gradient of the energy as work and energy-supply terms, including the energy flux of the gravitational waves. Projecting this equation along a trapping horizon yields a first law of black-hole dynamics containing the expected term involving area and surface gravity, where the dynamic surface gravity is defined with respect to the canonical flow of time. A first law for dynamic cosmic strings also follows. The Einstein equation is written as three wave equations plus the first law, each with sources determined by the combined energy tensor of the matter and gravitational waves. |
1112.2224 | Jennifer Driggers | Jennifer C. Driggers, Matthew Evans, Keenan Pepper, and Rana Adhikari | Active noise cancellation in a suspended interferometer | PACS numbers: 04.80.Nn, 95.55.Ym, 07.60.Ly, 42.62.Eh | null | 10.1063/1.3675891 | null | gr-qc astro-ph.IM physics.ins-det | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We demonstrate feed-forward vibration isolation on a suspended Fabry-Perot
interferometer using Wiener filtering and a variant of the common Least Mean
Square (LMS) adaptive filter algorithm. We compare the experimental results
with theoretical estimates of the cancellation efficiency. Using data from the
recent LIGO Science Run, we also estimate the impact of this technique on full
scale gravitational wave interferometers. In the future, we expect to use this
technique to also remove acoustic, magnetic, and gravitational noise
perturbations from the LIGO interferometers. This noise cancellation technique
is simple enough to implement in standard laboratory environments and can be
used to improve SNR for a variety of high precision experiments.
| [
{
"created": "Fri, 9 Dec 2011 22:26:57 GMT",
"version": "v1"
}
] | 2015-06-03 | [
[
"Driggers",
"Jennifer C.",
""
],
[
"Evans",
"Matthew",
""
],
[
"Pepper",
"Keenan",
""
],
[
"Adhikari",
"Rana",
""
]
] | We demonstrate feed-forward vibration isolation on a suspended Fabry-Perot interferometer using Wiener filtering and a variant of the common Least Mean Square (LMS) adaptive filter algorithm. We compare the experimental results with theoretical estimates of the cancellation efficiency. Using data from the recent LIGO Science Run, we also estimate the impact of this technique on full scale gravitational wave interferometers. In the future, we expect to use this technique to also remove acoustic, magnetic, and gravitational noise perturbations from the LIGO interferometers. This noise cancellation technique is simple enough to implement in standard laboratory environments and can be used to improve SNR for a variety of high precision experiments. |
2103.08430 | Iver Brevik | I. Brevik, A. V. Timoshkin and Tanmoy Paul | The effect of thermal radiation on singularities in the dark universe | 8 pages, to appear in Int. J. Geom. Meth. Mod. Phys | Int. J. Geom. Meth. Mod. Phys. 18, No 7, 2150113 (2021) | 10.1142/S0219887821501139 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Cosmological models with an inhomogeneous viscous dark fluid, coupled with
dark matter in the Friedmann- Robertson-Walker (FRW) flat universe, are
considered. The influence of thermal effects caused by Hawking radiation on the
visible horizon is studied, in connection with the classified type I and type
III singularities which are known to occur within a finite amount of time.
Allowance of thermal effects implies that a transition to a type II singularity
can take place, in a finite time. We take into account a bulk viscosity of the
dark fluid, observing the equation of state in the case of radiation, and find
that there is a qualitative change in the singular universe of type I: it may
pass into a singularity of type III, or it may avoid the singularity at all.
| [
{
"created": "Mon, 15 Mar 2021 14:58:35 GMT",
"version": "v1"
}
] | 2021-08-23 | [
[
"Brevik",
"I.",
""
],
[
"Timoshkin",
"A. V.",
""
],
[
"Paul",
"Tanmoy",
""
]
] | Cosmological models with an inhomogeneous viscous dark fluid, coupled with dark matter in the Friedmann- Robertson-Walker (FRW) flat universe, are considered. The influence of thermal effects caused by Hawking radiation on the visible horizon is studied, in connection with the classified type I and type III singularities which are known to occur within a finite amount of time. Allowance of thermal effects implies that a transition to a type II singularity can take place, in a finite time. We take into account a bulk viscosity of the dark fluid, observing the equation of state in the case of radiation, and find that there is a qualitative change in the singular universe of type I: it may pass into a singularity of type III, or it may avoid the singularity at all. |
2306.12064 | Andronikos Paliathanasis | Andronikos Paliathanasis | Reconstruction of $\Lambda$CDM Universe from Noether symmetries in
Chameleon gravity | 23 pages, 2 figures, to appear in Physics of the Dark Universe | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We apply the Noether symmetries to constrain the unknown functions of
chameleon gravity in the cosmological scenario of a spatially flat
Friedmann--Lema\^{\i}tre--Robertson--Walker space-time with an ideal gas. For
this gravitational model the field equations admit a point-like Lagrangian with
as unknown functions the scalar field potential and the coupling function which
is responsible for the chameleon mechanism. Noether's first theorem provides us
with four sets of closed-form functional forms for which variational symmetries
exist. We construct the corresponding conservation laws and we use them in
order to determine new analytic solutions in chameleon gravity. From the
analysis of the physical properties of the new solution it follows that in the
late universe they can reproduce the $\Lambda$CDM model without having to
assume the presence of a pressureless fluid in the cosmological fluid.
| [
{
"created": "Wed, 21 Jun 2023 07:21:01 GMT",
"version": "v1"
}
] | 2023-06-22 | [
[
"Paliathanasis",
"Andronikos",
""
]
] | We apply the Noether symmetries to constrain the unknown functions of chameleon gravity in the cosmological scenario of a spatially flat Friedmann--Lema\^{\i}tre--Robertson--Walker space-time with an ideal gas. For this gravitational model the field equations admit a point-like Lagrangian with as unknown functions the scalar field potential and the coupling function which is responsible for the chameleon mechanism. Noether's first theorem provides us with four sets of closed-form functional forms for which variational symmetries exist. We construct the corresponding conservation laws and we use them in order to determine new analytic solutions in chameleon gravity. From the analysis of the physical properties of the new solution it follows that in the late universe they can reproduce the $\Lambda$CDM model without having to assume the presence of a pressureless fluid in the cosmological fluid. |
2206.05645 | Yang Huang | Yang Huang and Hongsheng Zhang | True gravitational atom: Spherical cloud of dilatonic black holes | 7 pages, 5 figures, accepted for publication in PRD | null | 10.1103/PhysRevD.105.124056 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Black hole as elementary particle is a fairly glamorous idea. For ordinary
black holes, a surrounding particle inevitably penetrates into the interior of
the hole since the center of the hole is an infinite potential well. For the
first time we demonstrate that an extreme dilatonic black hole in spherical
symmetry perfectly behaves as an atom, in the sense that its surrounding cloud
of particles are completely stable. Thus we reach a spherical cloud of
dilatonic black hole. We find exact wave functions of the cloud for arbitrary
gravitational fine structure constant $\mu M$, and clear the underlying
physical nature of the stability. Through careful studies of the exact wave
function, we find the spectrum of this system. We discuss the physical meaning
of this discovery especially from considerations of entropy, and the resultant
possibility to explore quantization of gravitational waves from coming
observations.
| [
{
"created": "Sun, 12 Jun 2022 03:12:17 GMT",
"version": "v1"
}
] | 2022-07-13 | [
[
"Huang",
"Yang",
""
],
[
"Zhang",
"Hongsheng",
""
]
] | Black hole as elementary particle is a fairly glamorous idea. For ordinary black holes, a surrounding particle inevitably penetrates into the interior of the hole since the center of the hole is an infinite potential well. For the first time we demonstrate that an extreme dilatonic black hole in spherical symmetry perfectly behaves as an atom, in the sense that its surrounding cloud of particles are completely stable. Thus we reach a spherical cloud of dilatonic black hole. We find exact wave functions of the cloud for arbitrary gravitational fine structure constant $\mu M$, and clear the underlying physical nature of the stability. Through careful studies of the exact wave function, we find the spectrum of this system. We discuss the physical meaning of this discovery especially from considerations of entropy, and the resultant possibility to explore quantization of gravitational waves from coming observations. |
1708.02624 | Abhik Kumar Sanyal Dr. | Nayem Sk. and Abhik Kumar Sanyal | On the equivalence between different canonical forms of F(R) theory of
gravity | 10 pages, o figures | null | 10.1142/S0218271818500852 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Classical equivalence between Jordan's and Einstein's frame counterparts of
F(R) theory of gravity has recently been questioned, since the two produce
different Noether symmetries, which couldn't be translated back and forth using
transformation relations. Here we add the Hamiltonian constraint equation,
which is essentially the time-time component of Einstein's equation, through a
Lagrange multiplier to the existence condition for Noether symmetry to show
that all the three different canonical structures of F(R) theory of gravity,
including the one which follows from Lagrange multiplier technique, admit each
and every available symmetry independently. This establishes classical
equivalence amongst all the three.
| [
{
"created": "Sat, 5 Aug 2017 05:28:16 GMT",
"version": "v1"
}
] | 2018-06-27 | [
[
"Sk.",
"Nayem",
""
],
[
"Sanyal",
"Abhik Kumar",
""
]
] | Classical equivalence between Jordan's and Einstein's frame counterparts of F(R) theory of gravity has recently been questioned, since the two produce different Noether symmetries, which couldn't be translated back and forth using transformation relations. Here we add the Hamiltonian constraint equation, which is essentially the time-time component of Einstein's equation, through a Lagrange multiplier to the existence condition for Noether symmetry to show that all the three different canonical structures of F(R) theory of gravity, including the one which follows from Lagrange multiplier technique, admit each and every available symmetry independently. This establishes classical equivalence amongst all the three. |
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