id stringlengths 9 13 | submitter stringlengths 1 64 ⌀ | authors stringlengths 5 22.9k | title stringlengths 4 245 | comments stringlengths 1 548 ⌀ | journal-ref stringlengths 4 362 ⌀ | doi stringlengths 12 82 ⌀ | report-no stringlengths 2 281 ⌀ | categories stringclasses 793 values | license stringclasses 9 values | orig_abstract stringlengths 24 1.95k | versions listlengths 1 30 | update_date stringlengths 10 10 | authors_parsed listlengths 1 1.74k | abstract stringlengths 21 1.95k |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
gr-qc/9801054 | Jiri Podolsky | J. Podolsky, K. Vesely | New examples of sandwich gravitational waves and their impulsive limit | 9 pages, to be published in Czech. J. Phys | Czech.J.Phys. 48 (1998) 871-878 | 10.1023/A:1022869004605 | KTF MFF UK JP2 | gr-qc | null | Non-standard sandwich gravitational waves are constructed from the
homogeneous pp vacuum solution and the motions of free test particles in the
space-times are calculated explicitly. They demonstrate the caustic property of
sandwich waves. By performing limits to impulsive gravitational wave it is
demonstrated that the resulting particle motions are identical regardless of
the ''initial'' sandwich.
| [
{
"created": "Thu, 15 Jan 1998 15:22:27 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Podolsky",
"J.",
""
],
[
"Vesely",
"K.",
""
]
] | Non-standard sandwich gravitational waves are constructed from the homogeneous pp vacuum solution and the motions of free test particles in the space-times are calculated explicitly. They demonstrate the caustic property of sandwich waves. By performing limits to impulsive gravitational wave it is demonstrated that the resulting particle motions are identical regardless of the ''initial'' sandwich. |
1908.06220 | Jose Edgar Madriz Aguilar Dr. | Jos\'e Edgar Madriz Aguilar, J. Zamarripa, M. Montes, C. Romero | Higgs inflation in complex geometrical scalar-tensor theory of gravity | 7 pages, no figures | Physics of the Dark Universe 28 (2020) 100480 | 10.1016/j.dark.2020.100480 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive a Higgs inflationary model in the context of a complex geometrical
scalar-tensor theory of gravity. In this model the Higgs inflaton scalar field
has geometrical origin playing the role of the Weyl scalar field in the
original non-riemannian background geometry. The energy scale enough to
generate inflation from the Higgs energy scale is achieved due to the
compatibility of the theory with its background complex Weyl-integrable
geometry. We found that for a number of e-foldings $N=63$, a nearly scale
invariant spectrum for the inflaton is obtained with an spectral index
$n_s\simeq 0.9735$ and a scalar to tensor ratio $r\simeq 0.01$, which are in
agreement with Planck observational data.
| [
{
"created": "Sat, 17 Aug 2019 01:26:00 GMT",
"version": "v1"
}
] | 2020-07-14 | [
[
"Aguilar",
"José Edgar Madriz",
""
],
[
"Zamarripa",
"J.",
""
],
[
"Montes",
"M.",
""
],
[
"Romero",
"C.",
""
]
] | We derive a Higgs inflationary model in the context of a complex geometrical scalar-tensor theory of gravity. In this model the Higgs inflaton scalar field has geometrical origin playing the role of the Weyl scalar field in the original non-riemannian background geometry. The energy scale enough to generate inflation from the Higgs energy scale is achieved due to the compatibility of the theory with its background complex Weyl-integrable geometry. We found that for a number of e-foldings $N=63$, a nearly scale invariant spectrum for the inflaton is obtained with an spectral index $n_s\simeq 0.9735$ and a scalar to tensor ratio $r\simeq 0.01$, which are in agreement with Planck observational data. |
gr-qc/0702014 | Plamen Fiziev | Plamen P. Fiziev | Exact Solutions of Regge-Wheeler Equation | 13 pages, 8 figures, latex file. Talk given at XXIV Spanish
Relativity Meeting E.R.E. 2006, to appear in Journal of Physics, Conference
Series | J.Phys.Conf.Ser.66:012016,2007 | 10.1088/1742-6596/66/1/012016 | SU-TH0207 | gr-qc | null | The Regge-Wheeler equation describes the axial perturbations of Schwarzschild
metric in linear approximation. We present its exact solutions in terms of the
confluent Heun's functions, the basic properties of the general solution, novel
analytical approach and numerical techniques for study of different boundary
problems which correspond to quasi-normal modes of black holes and other simple
models of compact objects. We depict in more detail the exact solutions of
Regge-Wheeler equation in the Schwarzschild black hole interior and on
Kruscal-Szekeres manifold.
| [
{
"created": "Fri, 2 Feb 2007 18:49:37 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Fiziev",
"Plamen P.",
""
]
] | The Regge-Wheeler equation describes the axial perturbations of Schwarzschild metric in linear approximation. We present its exact solutions in terms of the confluent Heun's functions, the basic properties of the general solution, novel analytical approach and numerical techniques for study of different boundary problems which correspond to quasi-normal modes of black holes and other simple models of compact objects. We depict in more detail the exact solutions of Regge-Wheeler equation in the Schwarzschild black hole interior and on Kruscal-Szekeres manifold. |
1701.07132 | Hwa-Tung Nieh | H.T. Nieh | Torsion and Gauge Invariance in Maxwell-Dirac Electrodynamics | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It has been known for a long time that the presence of torsion is in conflict
with gauge invariance of the the electromagnetic field in curved Riemann-Cartan
space if the Maxwell field is minimally coupled to the curved gravitational
space through the covariant derivative. In search for a possible solution, we
consider in this note the system of Maxwell-Dirac electrodynamics in
Riemann-Cartan space. Through investigating consistency of the field equations,
and taking cue from the scale invariance properties of the system, we come up
with a solution that satisfies gauge invariance without having to dispense with
torsion in the coupled Maxwell-Dirac system. This is achieved by modifying the
connection that appears in the covariant derivative for the Maxwell field. The
modified connection turns out to be in the form of a Weyl connection, with the
torsion trace vector playing the effective role of a Weyl gauge field. With
this modified connection, which is symmetrical, the Lorentz-spin current of the
photon field is seen to vanish. In addition, except for the Dirac mass term,
the system exhibits local scale invariance. The same consideration applies to
all gauge theories, abelian or non-ableian, in the standard model of particle
physics.
| [
{
"created": "Wed, 25 Jan 2017 01:41:08 GMT",
"version": "v1"
},
{
"created": "Sat, 28 Jan 2017 05:58:18 GMT",
"version": "v2"
}
] | 2017-01-31 | [
[
"Nieh",
"H. T.",
""
]
] | It has been known for a long time that the presence of torsion is in conflict with gauge invariance of the the electromagnetic field in curved Riemann-Cartan space if the Maxwell field is minimally coupled to the curved gravitational space through the covariant derivative. In search for a possible solution, we consider in this note the system of Maxwell-Dirac electrodynamics in Riemann-Cartan space. Through investigating consistency of the field equations, and taking cue from the scale invariance properties of the system, we come up with a solution that satisfies gauge invariance without having to dispense with torsion in the coupled Maxwell-Dirac system. This is achieved by modifying the connection that appears in the covariant derivative for the Maxwell field. The modified connection turns out to be in the form of a Weyl connection, with the torsion trace vector playing the effective role of a Weyl gauge field. With this modified connection, which is symmetrical, the Lorentz-spin current of the photon field is seen to vanish. In addition, except for the Dirac mass term, the system exhibits local scale invariance. The same consideration applies to all gauge theories, abelian or non-ableian, in the standard model of particle physics. |
0711.4209 | Yakov Itin | Yakov Itin (Institute of Mathematics, Hebrew University of Jerusalem,
and Jerusalem College of Technology) | Coframe geometry and gravity | to be published in "Classical and Quantum Gravity Research Progress",
Nova Science Publishers, Inc | null | null | null | gr-qc | null | The possible extensions of GR for description of fermions on a curved space,
for supergravity and for loop quantum gravity require a richer set of 16
independent variables. These variables can be assembled in a coframe field,
i.e., a local set of four linearly independent 1-forms. In the ordinary
formulation, the coframe gravity does not have any connection to a specific
geometry even being constructed from the geometrical meaningful objects. A
geometrization of the coframe gravity is an aim of this paper. We construct a
complete class of the coframe connections which are linear in the first order
derivatives of the coframe field on an $n$ dimensional manifolds with and
without a metric. The subclasses of the torsion-free, metric-compatible and
flat connections are derived. We also study the behavior of the geometrical
structures under local transformations of the coframe. The remarkable fact is
an existence of a subclass of connections which are invariant when the
infinitesimal transformations satisfy the Maxwell-like system of equations. In
the framework of the coframe geometry construction, we propose a geometrical
action for the coframe gravity. It is similar to the Einstein-Hilbert action of
GR, but the scalar curvature is constructed from the general coframe
connection. We show that this geometric Lagrangian is equivalent to the coframe
Lagrangian up to a total derivative term. Moreover there is a family of coframe
connections which Lagrangian does not include the higher order terms at all. In
this case, the equivalence is complete.
| [
{
"created": "Tue, 27 Nov 2007 10:07:24 GMT",
"version": "v1"
}
] | 2019-08-12 | [
[
"Itin",
"Yakov",
"",
"Institute of Mathematics, Hebrew University of Jerusalem,\n and Jerusalem College of Technology"
]
] | The possible extensions of GR for description of fermions on a curved space, for supergravity and for loop quantum gravity require a richer set of 16 independent variables. These variables can be assembled in a coframe field, i.e., a local set of four linearly independent 1-forms. In the ordinary formulation, the coframe gravity does not have any connection to a specific geometry even being constructed from the geometrical meaningful objects. A geometrization of the coframe gravity is an aim of this paper. We construct a complete class of the coframe connections which are linear in the first order derivatives of the coframe field on an $n$ dimensional manifolds with and without a metric. The subclasses of the torsion-free, metric-compatible and flat connections are derived. We also study the behavior of the geometrical structures under local transformations of the coframe. The remarkable fact is an existence of a subclass of connections which are invariant when the infinitesimal transformations satisfy the Maxwell-like system of equations. In the framework of the coframe geometry construction, we propose a geometrical action for the coframe gravity. It is similar to the Einstein-Hilbert action of GR, but the scalar curvature is constructed from the general coframe connection. We show that this geometric Lagrangian is equivalent to the coframe Lagrangian up to a total derivative term. Moreover there is a family of coframe connections which Lagrangian does not include the higher order terms at all. In this case, the equivalence is complete. |
1601.08230 | Mikhail Volkov | Mikhail S. Volkov | Hairy black holes in the XX-th and XXI-st centuries | 20 pages, rapporteur article for the MG14 section on hairy black
holes | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This is a brief summary of the most important hairy black hole solutions in
3+1 spacetime dimensions discovered over the last 25 years. These were first of
all the Einstein-Yang-Mills black holes and their various generalizations
including the Higgs field, the dilaton and the curvature corrections, and also
the Skyrme black holes. More recently, these were black holes supporting a
scalar field violating the energy conditions or non-minimally coupled to
gravity, and also spinning black holes with massive complex scalar hair.
Finally, these were black holes with massive graviton hair.
| [
{
"created": "Fri, 29 Jan 2016 19:52:22 GMT",
"version": "v1"
}
] | 2016-02-01 | [
[
"Volkov",
"Mikhail S.",
""
]
] | This is a brief summary of the most important hairy black hole solutions in 3+1 spacetime dimensions discovered over the last 25 years. These were first of all the Einstein-Yang-Mills black holes and their various generalizations including the Higgs field, the dilaton and the curvature corrections, and also the Skyrme black holes. More recently, these were black holes supporting a scalar field violating the energy conditions or non-minimally coupled to gravity, and also spinning black holes with massive complex scalar hair. Finally, these were black holes with massive graviton hair. |
gr-qc/0403086 | Daniel M\"uller | Daniel Muller | Casimir Effect in Compact Universes | 16 pages, 8 figures, Invited talk at the Theoretical Cosmology
section of the Tenth Marcel Grossmann Meeting on General Relativity, Rio de
Janeiro, Brazil, 20-26 July, 2003 | null | 10.1142/9789812704030_0175 | null | gr-qc | null | The Casimir effect in compact hyperbolic Universes was numerically obtained
in previous publications. In this talk, I expose these results.
| [
{
"created": "Fri, 19 Mar 2004 23:43:41 GMT",
"version": "v1"
}
] | 2016-11-09 | [
[
"Muller",
"Daniel",
""
]
] | The Casimir effect in compact hyperbolic Universes was numerically obtained in previous publications. In this talk, I expose these results. |
1310.5333 | Alexei Zayats | Alexander B. Balakin, Ruslan K. Muharlyamov, Alexei E. Zayats | Electromagnetic waves in an axion-active relativistic plasma
non-minimally coupled to gravity | 19 pages, 9 figures, published version | Eur. Phys. J. C 73: 2647, 2013 | 10.1140/epjc/s10052-013-2647-8 | null | gr-qc astro-ph.CO hep-th physics.plasm-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider cosmological applications of a new self-consistent system of
equations, accounting for a nonminimal coupling of the gravitational,
electromagnetic and pseudoscalar (axion) fields in a relativistic plasma. We
focus on dispersion relations for electromagnetic perturbations in an initially
isotropic ultrarelativistic plasma coupled to the gravitational and axion
fields in the framework of isotropic homogeneous cosmological model of the de
Sitter type. We classify the longitudinal and transversal electromagnetic modes
in an axionically active plasma and distinguish between waves (damping,
instable or running), and nonharmonic perturbations (damping or instable). We
show that for the special choice of the guiding model parameters the
transversal electromagnetic waves in the axionically active plasma,
nonminimally coupled to gravity, can propagate with the phase velocity less
than speed of light in vacuum, thus displaying a possibility for a new type of
resonant particle-wave interactions.
| [
{
"created": "Sun, 20 Oct 2013 14:29:45 GMT",
"version": "v1"
},
{
"created": "Tue, 26 Nov 2013 15:37:55 GMT",
"version": "v2"
}
] | 2013-12-17 | [
[
"Balakin",
"Alexander B.",
""
],
[
"Muharlyamov",
"Ruslan K.",
""
],
[
"Zayats",
"Alexei E.",
""
]
] | We consider cosmological applications of a new self-consistent system of equations, accounting for a nonminimal coupling of the gravitational, electromagnetic and pseudoscalar (axion) fields in a relativistic plasma. We focus on dispersion relations for electromagnetic perturbations in an initially isotropic ultrarelativistic plasma coupled to the gravitational and axion fields in the framework of isotropic homogeneous cosmological model of the de Sitter type. We classify the longitudinal and transversal electromagnetic modes in an axionically active plasma and distinguish between waves (damping, instable or running), and nonharmonic perturbations (damping or instable). We show that for the special choice of the guiding model parameters the transversal electromagnetic waves in the axionically active plasma, nonminimally coupled to gravity, can propagate with the phase velocity less than speed of light in vacuum, thus displaying a possibility for a new type of resonant particle-wave interactions. |
1412.0010 | Ettore Minguzzi | E. Minguzzi | Special relativity as the limit of an Aristotelian universal friction
theory under Reye's assumption | 19 pages | null | null | null | gr-qc physics.class-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This work explores a classical mechanical theory under two further
assumptions: (a) there is a universal dry friction force (Aristotelian
mechanics), and (b) the variation of the mass of a body due to wear is
proportional to the work done by the friction force on the body (Reye's
hypothesis). It is shown that mass depends on velocity as in Special
Relativity, and that the velocity is constant for a particular characteristic
value. In the limit of vanishing friction the theory satisfies a relativity
principle as bodies do not decelerate and, therefore, the absolute frame
becomes unobservable. However, the limit theory is not Newtonian mechanics,
with its Galilei group symmetry, but rather Special Relativity. This result
suggests to regard Special Relativity as the limit of a theory presenting
universal friction and exchange of mass-energy with a reservoir (vacuum). Thus,
quite surprisingly, Special Relativity follows from the absolute space (ether)
concept and could have been discovered following studies of Aristotelian
mechanics and friction. We end the work confronting the full theory with
observations. It predicts the Hubble law through tired light, and hence it is
incompatible with supernova light curves unless both mechanisms of tired light
(locally) and universe expansion (non-locally) are at work. It also nicely
accounts for some challenging numerical coincidences involving phenomena under
low acceleration.
| [
{
"created": "Fri, 28 Nov 2014 12:01:43 GMT",
"version": "v1"
}
] | 2014-12-02 | [
[
"Minguzzi",
"E.",
""
]
] | This work explores a classical mechanical theory under two further assumptions: (a) there is a universal dry friction force (Aristotelian mechanics), and (b) the variation of the mass of a body due to wear is proportional to the work done by the friction force on the body (Reye's hypothesis). It is shown that mass depends on velocity as in Special Relativity, and that the velocity is constant for a particular characteristic value. In the limit of vanishing friction the theory satisfies a relativity principle as bodies do not decelerate and, therefore, the absolute frame becomes unobservable. However, the limit theory is not Newtonian mechanics, with its Galilei group symmetry, but rather Special Relativity. This result suggests to regard Special Relativity as the limit of a theory presenting universal friction and exchange of mass-energy with a reservoir (vacuum). Thus, quite surprisingly, Special Relativity follows from the absolute space (ether) concept and could have been discovered following studies of Aristotelian mechanics and friction. We end the work confronting the full theory with observations. It predicts the Hubble law through tired light, and hence it is incompatible with supernova light curves unless both mechanisms of tired light (locally) and universe expansion (non-locally) are at work. It also nicely accounts for some challenging numerical coincidences involving phenomena under low acceleration. |
1702.01110 | Andrea Maselli | Andrea Maselli, Kostas Kokkotas, Pablo Laguna | Observing binary black hole ringdowns by advanced gravitational wave
detectors | Third generation of detectors included in the analysis and Improved
discussion of the results. Accepted for publication on PRD | Phys. Rev. D 95, 104026 (2017) | 10.1103/PhysRevD.95.104026 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The direct discovery of gravitational waves from compact binary systems leads
for the first time to explore the possibility of black hole spectroscopy. Newly
formed black holes produced by coalescing events are copious emitters of
gravitational radiation, in the form of damped sinusoids, the quasi normal
modes. The latter provide a precious source of information on the nature of
gravity in the strong field regime, as they represent a powerful tool to
investigate the validity of the no-hair theorem. In this work we perform a
systematic study on the accuracy with which current and future interferometers
will measure the fundamental parameters of ringdown events, such as frequencies
and damping times. We analyze how these errors affect the estimate of the mass
and the angular momentum of the final black hole, constraining the parameter
space which will lead to the most precise measurements. We explore both single
and multimode events, showing how the uncertainties evolve when multiple
detectors are available. We also prove that, for second generation of
interferometers, a network of instruments is a crucial and necessary ingredient
to perform strong-gravity tests of the no-hair theorem. Finally, we analyze the
constraints that a third generation of detectors may be able to set on the
mode's parameters, comparing the projected bounds against those obtained for
current facilities.
| [
{
"created": "Fri, 3 Feb 2017 18:49:26 GMT",
"version": "v1"
},
{
"created": "Fri, 28 Apr 2017 07:37:52 GMT",
"version": "v2"
}
] | 2017-05-24 | [
[
"Maselli",
"Andrea",
""
],
[
"Kokkotas",
"Kostas",
""
],
[
"Laguna",
"Pablo",
""
]
] | The direct discovery of gravitational waves from compact binary systems leads for the first time to explore the possibility of black hole spectroscopy. Newly formed black holes produced by coalescing events are copious emitters of gravitational radiation, in the form of damped sinusoids, the quasi normal modes. The latter provide a precious source of information on the nature of gravity in the strong field regime, as they represent a powerful tool to investigate the validity of the no-hair theorem. In this work we perform a systematic study on the accuracy with which current and future interferometers will measure the fundamental parameters of ringdown events, such as frequencies and damping times. We analyze how these errors affect the estimate of the mass and the angular momentum of the final black hole, constraining the parameter space which will lead to the most precise measurements. We explore both single and multimode events, showing how the uncertainties evolve when multiple detectors are available. We also prove that, for second generation of interferometers, a network of instruments is a crucial and necessary ingredient to perform strong-gravity tests of the no-hair theorem. Finally, we analyze the constraints that a third generation of detectors may be able to set on the mode's parameters, comparing the projected bounds against those obtained for current facilities. |
1003.4584 | Alexei Zayats | Alexander B. Balakin, Jos\'e P. S. Lemos, Alexei E. Zayats | Nonminimal coupling for the gravitational and electromagnetic fields:
Traversable electric wormholes | 15 pages, 9 figures | Phys.Rev.D81:084015,2010 | 10.1103/PhysRevD.81.084015 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss new exact solutions of a three-parameter nonminimal
Einstein-Maxwell model. The solutions describe static spherically symmetric
objects with and without center, supported by an electric field nonminimally
coupled to gravity. We focus on a unique one-parameter model, which admits an
exact solution for a traversable electrically charged wormhole connecting two
universes, one asymptotically flat the other asymptotically de Sitter ones. The
relation between the asymptotic mass and charge of the wormhole and its throat
radius is analyzed. The wormhole solution found is thus a nonminimal
realization of the idea of Wheeler about charge without charge and shows that,
if the world is somehow nonminimal in the coupling of gravity to
electromagnetism, then wormhole appearance, or perhaps construction, is
possible.
| [
{
"created": "Wed, 24 Mar 2010 06:49:48 GMT",
"version": "v1"
},
{
"created": "Thu, 15 Apr 2010 19:53:26 GMT",
"version": "v2"
}
] | 2010-04-16 | [
[
"Balakin",
"Alexander B.",
""
],
[
"Lemos",
"José P. S.",
""
],
[
"Zayats",
"Alexei E.",
""
]
] | We discuss new exact solutions of a three-parameter nonminimal Einstein-Maxwell model. The solutions describe static spherically symmetric objects with and without center, supported by an electric field nonminimally coupled to gravity. We focus on a unique one-parameter model, which admits an exact solution for a traversable electrically charged wormhole connecting two universes, one asymptotically flat the other asymptotically de Sitter ones. The relation between the asymptotic mass and charge of the wormhole and its throat radius is analyzed. The wormhole solution found is thus a nonminimal realization of the idea of Wheeler about charge without charge and shows that, if the world is somehow nonminimal in the coupling of gravity to electromagnetism, then wormhole appearance, or perhaps construction, is possible. |
1309.7332 | Massimiliano Rinaldi | Massimiliano Rinaldi | The dark aftermath of Higgs inflation | Matches the version accepted by EPJ+ | Eur. Phys. J. Plus (2014) 129: 56 | 10.1140/epjp/i2014-14056-8 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this letter we study the dynamics of the late Universe when a nonminimally
coupled Higgs field is present. In general, the nonminimal coupling leads to a
nontrivial mixing between the gravitational degrees of freedom and the
Goldstone massless bosons. We know that this is irrelevant during the
inflationary phase. In contrast, in the late Universe the nonminimal coupling
affects the classical equations of motion, leading to an acceleration of the
expansion rate or to a collapse that forms Q-balls.
| [
{
"created": "Fri, 27 Sep 2013 18:55:32 GMT",
"version": "v1"
},
{
"created": "Tue, 8 Oct 2013 10:30:03 GMT",
"version": "v2"
},
{
"created": "Mon, 25 Nov 2013 14:26:46 GMT",
"version": "v3"
},
{
"created": "Mon, 13 Jan 2014 18:01:14 GMT",
"version": "v4"
},
{
"cr... | 2014-03-31 | [
[
"Rinaldi",
"Massimiliano",
""
]
] | In this letter we study the dynamics of the late Universe when a nonminimally coupled Higgs field is present. In general, the nonminimal coupling leads to a nontrivial mixing between the gravitational degrees of freedom and the Goldstone massless bosons. We know that this is irrelevant during the inflationary phase. In contrast, in the late Universe the nonminimal coupling affects the classical equations of motion, leading to an acceleration of the expansion rate or to a collapse that forms Q-balls. |
2005.13957 | Celia Escamilla-Rivera | Celia Escamilla-Rivera, A. Hern\'andez-Almada, Miguel A.
Garc\'ia-Aspeitia and V. Motta | Linear perturbations spectra for dynamical dark energy inspired by
modified gravity | 8 pages, 3 figures, 2 tables. Version accepted for publication in the
International Journal of Modern Physics D | International Journal of Modern Physics D 2021 | 10.1142/S0218271821500772 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we study a particular modified gravity Equation of State, the
so-called Jaime-Jaber-Escamilla, that emerges from the first gravity modified
action principle and can reproduce three cosmological viable $f(R)$ theories:
the Starobinsky, Hu-Sawicki, and Exponential models . This EoS is a suitable
candidate to reproduce the dynamical dark energy behaviour already
reconstructed by the current data sets. Based on the joint statistical
analysis, we found that our results are still in good agreement (within
$1\sigma$) with the $\Lambda$CDM, while at perturbative level we notice that
the matter power spectrum normalisation factor $\sigma_8$ shows an agreement
with SDSS and SNeIa+IRAS at 1-$\sigma$ for the Starobinsky model and with
SDSS-vec for the Hu \& Sawicki and Exponential models. Furthermore, we found
that for the $H_0$ values, Starobinsky and Hu \& Sawicki show the least tension
in comparison with PL18 TT. All these aspects cannot be observed
\textit{directly} from other alternatives theories, were a equation of state is
difficult to compute analytically.
| [
{
"created": "Tue, 26 May 2020 00:39:53 GMT",
"version": "v1"
},
{
"created": "Thu, 27 May 2021 16:05:18 GMT",
"version": "v2"
}
] | 2021-07-07 | [
[
"Escamilla-Rivera",
"Celia",
""
],
[
"Hernández-Almada",
"A.",
""
],
[
"García-Aspeitia",
"Miguel A.",
""
],
[
"Motta",
"V.",
""
]
] | In this paper, we study a particular modified gravity Equation of State, the so-called Jaime-Jaber-Escamilla, that emerges from the first gravity modified action principle and can reproduce three cosmological viable $f(R)$ theories: the Starobinsky, Hu-Sawicki, and Exponential models . This EoS is a suitable candidate to reproduce the dynamical dark energy behaviour already reconstructed by the current data sets. Based on the joint statistical analysis, we found that our results are still in good agreement (within $1\sigma$) with the $\Lambda$CDM, while at perturbative level we notice that the matter power spectrum normalisation factor $\sigma_8$ shows an agreement with SDSS and SNeIa+IRAS at 1-$\sigma$ for the Starobinsky model and with SDSS-vec for the Hu \& Sawicki and Exponential models. Furthermore, we found that for the $H_0$ values, Starobinsky and Hu \& Sawicki show the least tension in comparison with PL18 TT. All these aspects cannot be observed \textit{directly} from other alternatives theories, were a equation of state is difficult to compute analytically. |
gr-qc/9710045 | Georges Bressange | C. Barrab\`es, G.F Bressange and P.A. Hogan | Colliding Plane Waves in Einstein-Maxwell Theory | 3 pages, TeX, no figures, to appear in Lett. Math. Phys | Lett.Math.Phys. 43 (1998) 263-265 | null | null | gr-qc | null | Recently a simple solution of the vacuum Einstein-Maxwell field equations was
given describing a plane electromagnetic shock wave sharing its wave front with
a plane gravitational impulse wave. We present here an exact solution of the
vacuum Einstein-Maxwell field equations describing the head-on collision of
such a wave with a plane gravitational impulse wave. The solution has the
Penrose-Khan solution and a solution obtained by Griffiths as separate limiting
cases.
| [
{
"created": "Wed, 8 Oct 1997 09:20:48 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Barrabès",
"C.",
""
],
[
"Bressange",
"G. F",
""
],
[
"Hogan",
"P. A.",
""
]
] | Recently a simple solution of the vacuum Einstein-Maxwell field equations was given describing a plane electromagnetic shock wave sharing its wave front with a plane gravitational impulse wave. We present here an exact solution of the vacuum Einstein-Maxwell field equations describing the head-on collision of such a wave with a plane gravitational impulse wave. The solution has the Penrose-Khan solution and a solution obtained by Griffiths as separate limiting cases. |
gr-qc/0210070 | Jerzy Matyjasek | Jerzy Matyjasek | Quantized massive scalar fields in the spacetime of a charged dilatonic
black hole | 16 pages, 4 figures | Acta Phys.Polon. B34 (2003) 3921-3946 | null | null | gr-qc | null | Employing the approximate effective action constructed from the coincidence
limit of the Hadamard-Minakshisundaram-DeWitt (HaMiDeW) coefficient a_{3}, the
renormalized stress-energy tensor of the quantized massive scalar field in the
spacetime of a static and electrically charged dilatonic black hole is
calculated. Special attention is paid to the minimally and conformally coupled
fields propagating in geometries with a=1, and to the power expansion of the
general stress-energy tensor for small values of charge. A compact expression
for the trace of the stress-energy tensor is presented.
| [
{
"created": "Sun, 20 Oct 2002 19:20:56 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Matyjasek",
"Jerzy",
""
]
] | Employing the approximate effective action constructed from the coincidence limit of the Hadamard-Minakshisundaram-DeWitt (HaMiDeW) coefficient a_{3}, the renormalized stress-energy tensor of the quantized massive scalar field in the spacetime of a static and electrically charged dilatonic black hole is calculated. Special attention is paid to the minimally and conformally coupled fields propagating in geometries with a=1, and to the power expansion of the general stress-energy tensor for small values of charge. A compact expression for the trace of the stress-energy tensor is presented. |
1412.4250 | Oleg Zaslavskii | O. B. Zaslavskii | Ultra-high energy collisions in static space-times: single versus
multi-black hole cases | 18 pages. Essentially expanded, presentation improved. To appear in
GRG | Gen. Rel. and Gravitation 47 (2015) 50 | 10.1007/s10714-015-1894-4 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider collision of two particles near static electrically charged
extremal black holes and elucidate the conditions under which the energy in the
centre of mass frame E_{c.m.} grows unbounded. For a single black hole, we
generalize the results obtained earlier for the Reissner-Nordstr\"om metric, to
distorted black holes. In the multi-black hole space-time, qualitatively new
features appear. If the point of collision is close to at least two horizons
simultaneously, unbounded E_{c.m.} are possible (i) without fine-tuning of
particles' parameters, (ii) for an arbitrary mutual orientation of two
velocities. Such a combination of properties (i) and (ii) has no analogues in
the single black hole case and facilitates the condition of getting unbounded
E_{c.m.}. Collisions in the electro-vacuum Majumdar-Papapetrou metric (several
extremal black holes in equilibrium) is analyzed explicitly.
| [
{
"created": "Sat, 13 Dec 2014 16:14:28 GMT",
"version": "v1"
},
{
"created": "Wed, 25 Mar 2015 20:39:38 GMT",
"version": "v2"
}
] | 2015-04-10 | [
[
"Zaslavskii",
"O. B.",
""
]
] | We consider collision of two particles near static electrically charged extremal black holes and elucidate the conditions under which the energy in the centre of mass frame E_{c.m.} grows unbounded. For a single black hole, we generalize the results obtained earlier for the Reissner-Nordstr\"om metric, to distorted black holes. In the multi-black hole space-time, qualitatively new features appear. If the point of collision is close to at least two horizons simultaneously, unbounded E_{c.m.} are possible (i) without fine-tuning of particles' parameters, (ii) for an arbitrary mutual orientation of two velocities. Such a combination of properties (i) and (ii) has no analogues in the single black hole case and facilitates the condition of getting unbounded E_{c.m.}. Collisions in the electro-vacuum Majumdar-Papapetrou metric (several extremal black holes in equilibrium) is analyzed explicitly. |
2107.00702 | Alessandro Fabbri | Roberto Balbinot and Alessandro Fabbri | Quantum correlations across the horizon in acoustic and gravitational
Black Holes | 35 pages, 16 figures. Final version | Phys. Rev. D105, 045010 (2022) | 10.1103/PhysRevD.105.045010 | null | gr-qc cond-mat.quant-gas hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate, within the framework of Quantum Field Theory in curved space,
the correlations across the horizon of a black hole in order to highlight the
particle-partner pair creation mechanism at the origin of Hawking radiation.
The analysis concerns both acoustic black holes, formed by Bose-Einstein
condensates, and gravitational black holes. More precisely, we have considered
a typical acoustic black hole metric with two asymptotic homogeneous regions
and the Schwarzschild metric as describing a gravitational black hole. By
considering equal time correlation functions, we find a striking disagreement
between the two cases: the expected characteristic peak centered along the
trajectories of the Hawking particles and their partners seems to appear only
for the acoustic black hole and not for the gravitational Schwarzschild one.
The reason for that is the existence of a 'quantum atmosphere' displaced from
the horizon as the locus of origin of Hawking radiation together, and this is
the crucial aspect, with the presence of a central singularity in the
gravitational case swallowing everything is trapped inside the horizon.
Correlations however are not absent in the gravitational case: to see them one
has simply to consider correlation functions at unequal times which indeed
display the expected peak.
| [
{
"created": "Thu, 1 Jul 2021 19:02:34 GMT",
"version": "v1"
},
{
"created": "Wed, 16 Feb 2022 12:44:51 GMT",
"version": "v2"
}
] | 2022-02-17 | [
[
"Balbinot",
"Roberto",
""
],
[
"Fabbri",
"Alessandro",
""
]
] | We investigate, within the framework of Quantum Field Theory in curved space, the correlations across the horizon of a black hole in order to highlight the particle-partner pair creation mechanism at the origin of Hawking radiation. The analysis concerns both acoustic black holes, formed by Bose-Einstein condensates, and gravitational black holes. More precisely, we have considered a typical acoustic black hole metric with two asymptotic homogeneous regions and the Schwarzschild metric as describing a gravitational black hole. By considering equal time correlation functions, we find a striking disagreement between the two cases: the expected characteristic peak centered along the trajectories of the Hawking particles and their partners seems to appear only for the acoustic black hole and not for the gravitational Schwarzschild one. The reason for that is the existence of a 'quantum atmosphere' displaced from the horizon as the locus of origin of Hawking radiation together, and this is the crucial aspect, with the presence of a central singularity in the gravitational case swallowing everything is trapped inside the horizon. Correlations however are not absent in the gravitational case: to see them one has simply to consider correlation functions at unequal times which indeed display the expected peak. |
1908.09842 | Kyriakos Destounis | Kyriakos Destounis, Rodrigo D. B. Fontana, Filipe C. Mena, Eleftherios
Papantonopoulos | Strong Cosmic Censorship in Horndeski Theory | 21 pages, 5 figures, to appear in JHEP | JHEP10(2019)280 | 10.1007/JHEP10(2019)280 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The strong cosmic censorship hypothesis has recently regained a lot of
attention in charged and rotating black holes immersed in de Sitter space.
Although the picture seems to be clearly leaning towards the validity of the
hypothesis in Kerr-de Sitter geometries, Reissner-Nordstr\"{o}m-de Sitter black
holes appear to be serious counter-examples. Here, we perform another test to
the hypothesis by using a scalar field perturbation non-minimally coupled to
the Einstein tensor propagating on Reissner-Nordstr\"{o}m-de Sitter spacetimes.
Such non-minimal derivative coupling is characteristic of Horndeski
scalar-tensor theories. Although the introduction of higher-order derivative
couplings in the energy-momentum tensor increases the regularity requirements
for the existence of weak solutions beyond the Cauchy horizon, we are still
able to find a small finite region in the black hole's parameter space where
strong cosmic censorship is violated.
| [
{
"created": "Mon, 26 Aug 2019 18:00:03 GMT",
"version": "v1"
},
{
"created": "Thu, 29 Aug 2019 15:56:19 GMT",
"version": "v2"
},
{
"created": "Wed, 16 Oct 2019 16:24:06 GMT",
"version": "v3"
}
] | 2019-11-04 | [
[
"Destounis",
"Kyriakos",
""
],
[
"Fontana",
"Rodrigo D. B.",
""
],
[
"Mena",
"Filipe C.",
""
],
[
"Papantonopoulos",
"Eleftherios",
""
]
] | The strong cosmic censorship hypothesis has recently regained a lot of attention in charged and rotating black holes immersed in de Sitter space. Although the picture seems to be clearly leaning towards the validity of the hypothesis in Kerr-de Sitter geometries, Reissner-Nordstr\"{o}m-de Sitter black holes appear to be serious counter-examples. Here, we perform another test to the hypothesis by using a scalar field perturbation non-minimally coupled to the Einstein tensor propagating on Reissner-Nordstr\"{o}m-de Sitter spacetimes. Such non-minimal derivative coupling is characteristic of Horndeski scalar-tensor theories. Although the introduction of higher-order derivative couplings in the energy-momentum tensor increases the regularity requirements for the existence of weak solutions beyond the Cauchy horizon, we are still able to find a small finite region in the black hole's parameter space where strong cosmic censorship is violated. |
1807.07234 | Hideki Asada | Yuki Hagihara, Naoya Era, Daisuke Iikawa, Hideki Asada | Probing gravitational wave polarizations with Advanced LIGO, Advanced
Virgo and KAGRA | 14 pages, 4 figures, Figure 4 is replaced, added one paragraph about
why the specific sky positions are O(100), accepted by PRD | Phys. Rev. D 98, 064035 (2018) | 10.1103/PhysRevD.98.064035 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Assuming that, for a given source of gravitational waves (GWs), we know its
sky position, as is the case of GW events with an electromagnetic counterpart
such as GW170817, we discuss a null stream method to probe GW polarizations
including spin-0 (scalar) GW modes and spin-1 (vector) modes, especially with
an expected network of Advanced LIGO, Advanced Virgo and KAGRA. For two
independent null streams for four non-co-aligned GW detectors, we study a
location on the sky, exactly at which the spin-0 modes of GWs vanish in any
null stream for the GW detector network, though the strain output at a detector
may contain the spin-0 modes. Our numerical calculations show that there exist
seventy sky positions that satisfy this condition of killing the spin-0 modes
in the null streams. If a GW source with an electromagnetic counterpart is
found in one of the seventy sky positions, the spin-1 modes will be testable
separately from the spin-0 modes by the null stream method. In addition, we
study a superposition of the two null streams to show that any one of the three
modes (one combined spin-0 and two spin-1 modes) can be eliminated by suitably
adjusting a weighted superposition of the null streams and thereby a set of the
remaining polarization modes can be experimentally tested.
| [
{
"created": "Thu, 19 Jul 2018 04:11:43 GMT",
"version": "v1"
},
{
"created": "Mon, 10 Sep 2018 06:47:27 GMT",
"version": "v2"
}
] | 2018-09-26 | [
[
"Hagihara",
"Yuki",
""
],
[
"Era",
"Naoya",
""
],
[
"Iikawa",
"Daisuke",
""
],
[
"Asada",
"Hideki",
""
]
] | Assuming that, for a given source of gravitational waves (GWs), we know its sky position, as is the case of GW events with an electromagnetic counterpart such as GW170817, we discuss a null stream method to probe GW polarizations including spin-0 (scalar) GW modes and spin-1 (vector) modes, especially with an expected network of Advanced LIGO, Advanced Virgo and KAGRA. For two independent null streams for four non-co-aligned GW detectors, we study a location on the sky, exactly at which the spin-0 modes of GWs vanish in any null stream for the GW detector network, though the strain output at a detector may contain the spin-0 modes. Our numerical calculations show that there exist seventy sky positions that satisfy this condition of killing the spin-0 modes in the null streams. If a GW source with an electromagnetic counterpart is found in one of the seventy sky positions, the spin-1 modes will be testable separately from the spin-0 modes by the null stream method. In addition, we study a superposition of the two null streams to show that any one of the three modes (one combined spin-0 and two spin-1 modes) can be eliminated by suitably adjusting a weighted superposition of the null streams and thereby a set of the remaining polarization modes can be experimentally tested. |
1901.10851 | Juan Mena-Fern\'andez | Juan Mena-Fern\'andez and Luis Manuel Gonz\'alez-Romero | Reconstruction of the neutron star equation of state from
$w$-quasinormal modes spectra with a piecewise polytropic meshing and
refinement method | 20 pages, 18 figures | Phys. Rev. D 99, 104005 (2019) | 10.1103/PhysRevD.99.104005 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we present a new approach to the inverse problem for
relativistic stars using quasinormal modes and the piecewise polytropic
parametrization of the equation of state. The algorithm is a piecewise
polytropic meshing and refinement method that reconstructs the neutron star
equation of state from experimental data of the mass and the $wI$-quasinormal
modes. We present an algorithm able to numerically calculate axial quasinormal
modes of neutron stars in an efficient way. We use an initial mesh of $27440$
equations of state in a $4$-volume of piecewise polytropic parameters that
contains most of the candidate equations of state used today. The refinement
process drives us to the reconstruction of the equation of state with a certain
precision. Using the reconstructed equation of state, we calculate predictions
for tidal deformability and slow rotation parameters (moment of inertia and
quadrupole moment, for example).
In order to check the method with an explicit example, we use as input data a
few (five) configurations of a given equation of state. We reconstruct the
equation of state in a quite good approximation, and then we compare the curves
of physical parameters from the original equation of state and the
reconstructed one. We obtain a relative difference for all of the parameters
smaller than $2.5\%$ except for the tidal deformability, for which we obtain a
relative difference smaller than $6.5\%$. We also study constraints from
GW170817 event for the reconstructed equation of state.
| [
{
"created": "Wed, 30 Jan 2019 14:33:17 GMT",
"version": "v1"
},
{
"created": "Tue, 23 Apr 2019 11:58:00 GMT",
"version": "v2"
},
{
"created": "Thu, 9 May 2019 10:01:35 GMT",
"version": "v3"
}
] | 2019-05-10 | [
[
"Mena-Fernández",
"Juan",
""
],
[
"González-Romero",
"Luis Manuel",
""
]
] | In this paper we present a new approach to the inverse problem for relativistic stars using quasinormal modes and the piecewise polytropic parametrization of the equation of state. The algorithm is a piecewise polytropic meshing and refinement method that reconstructs the neutron star equation of state from experimental data of the mass and the $wI$-quasinormal modes. We present an algorithm able to numerically calculate axial quasinormal modes of neutron stars in an efficient way. We use an initial mesh of $27440$ equations of state in a $4$-volume of piecewise polytropic parameters that contains most of the candidate equations of state used today. The refinement process drives us to the reconstruction of the equation of state with a certain precision. Using the reconstructed equation of state, we calculate predictions for tidal deformability and slow rotation parameters (moment of inertia and quadrupole moment, for example). In order to check the method with an explicit example, we use as input data a few (five) configurations of a given equation of state. We reconstruct the equation of state in a quite good approximation, and then we compare the curves of physical parameters from the original equation of state and the reconstructed one. We obtain a relative difference for all of the parameters smaller than $2.5\%$ except for the tidal deformability, for which we obtain a relative difference smaller than $6.5\%$. We also study constraints from GW170817 event for the reconstructed equation of state. |
1008.1028 | Abd El Fady Morcos | M.I. Wanas, A.B. Morcos and S.I. El Gammal | Lense-Thirring Field and the Solar Limb Effect | 7 pages conference | First Middle East and Aerica IAU- Regional Meeting Proceeding
MEARIM No.1,2008 | 10.1017/977403330200102 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Solar-Limb Effect is an observational phenomena connected to the solar
gravitational red-shift. It shows a variation of the magnitude of the
gravitational red-shift from the center to the limb of the solar disc. In the
present work an attempt, for interpreting this phenomena using a general
relativistic red-shift formula, is given . This formula takes into account the
effect of the the Sun's gravitational field, the effect of the solar rotation,
the effect of inclination of the line of sight and the motion of the observer.
In this study the gravitational field of the Sun is assumed to be given by
Lense-Thirring field instead of the Schwarzschild one. The Earth is assumed to
move along an elliptic orbit. Comparison with a previous relativistic study and
with observation is given.
| [
{
"created": "Thu, 5 Aug 2010 17:35:57 GMT",
"version": "v1"
}
] | 2010-08-06 | [
[
"Wanas",
"M. I.",
""
],
[
"Morcos",
"A. B.",
""
],
[
"Gammal",
"S. I. El",
""
]
] | Solar-Limb Effect is an observational phenomena connected to the solar gravitational red-shift. It shows a variation of the magnitude of the gravitational red-shift from the center to the limb of the solar disc. In the present work an attempt, for interpreting this phenomena using a general relativistic red-shift formula, is given . This formula takes into account the effect of the the Sun's gravitational field, the effect of the solar rotation, the effect of inclination of the line of sight and the motion of the observer. In this study the gravitational field of the Sun is assumed to be given by Lense-Thirring field instead of the Schwarzschild one. The Earth is assumed to move along an elliptic orbit. Comparison with a previous relativistic study and with observation is given. |
1511.08281 | Liu Zhao | Xin Hao, Bin Wu and Liu Zhao | Fluids and vortex from constrained fluctuations around C-metric black
hole | 19 pages, LaTeX. v2: added a new reference. v3: major revision | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | By foliating the four-dimensional C-metric black hole spacetime, we consider
a kind of initial-value-like formulation of the vacuum Einstein's equation, the
holographic initial data is a double consisting of the induced metric and the
Brown-York energy momentum tensor on an arbitrary initial hypersurface. Then by
perturbing the initial data that generates the background spacetime, it is
shown that, in an appropriate limit, the fluctuation modes are governed by the
continuity equation and the compressible Navier-Stokes equation which describe
the momentum transport in non-relativistic viscous fluid on a flat Newtonian
space. It turns out that the flat space fluid behaves as a pure vortex and the
viscosity to entropy ratio is subjected to the black hole acceleration.
| [
{
"created": "Thu, 26 Nov 2015 03:33:27 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Dec 2015 01:36:24 GMT",
"version": "v2"
},
{
"created": "Thu, 6 Apr 2017 01:03:50 GMT",
"version": "v3"
}
] | 2017-04-07 | [
[
"Hao",
"Xin",
""
],
[
"Wu",
"Bin",
""
],
[
"Zhao",
"Liu",
""
]
] | By foliating the four-dimensional C-metric black hole spacetime, we consider a kind of initial-value-like formulation of the vacuum Einstein's equation, the holographic initial data is a double consisting of the induced metric and the Brown-York energy momentum tensor on an arbitrary initial hypersurface. Then by perturbing the initial data that generates the background spacetime, it is shown that, in an appropriate limit, the fluctuation modes are governed by the continuity equation and the compressible Navier-Stokes equation which describe the momentum transport in non-relativistic viscous fluid on a flat Newtonian space. It turns out that the flat space fluid behaves as a pure vortex and the viscosity to entropy ratio is subjected to the black hole acceleration. |
1310.8495 | Muhammad Zaeem Ul Haq Bhatti | M. Sharif and M. Zaeem Ul Haq Bhatti | Structure Scalars In Charged Plane Symmetry | 12 pages | Mod. Phys. Lett A 27(2012)1250141 | 10.1142/S0217732312501416 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider non-adiabatic flow of the fluid possessing dissipation in the
form of shearing viscosity in electromagnetic field. The scalar functions
(structure scalars) for charged plane symmetry are formulated and are related
with the physical variables of the fluid. We also develop a relationship
between the Weyl tensor and other physical variables by using Taub mass
formalism. The role of electric charge as well as its physical significance for
the evolution of the shear tensor and expansion scalar are also explored.
Finally, we discuss a special case for dust with cosmological constant.
| [
{
"created": "Wed, 30 Oct 2013 14:52:09 GMT",
"version": "v1"
}
] | 2013-11-01 | [
[
"Sharif",
"M.",
""
],
[
"Bhatti",
"M. Zaeem Ul Haq",
""
]
] | We consider non-adiabatic flow of the fluid possessing dissipation in the form of shearing viscosity in electromagnetic field. The scalar functions (structure scalars) for charged plane symmetry are formulated and are related with the physical variables of the fluid. We also develop a relationship between the Weyl tensor and other physical variables by using Taub mass formalism. The role of electric charge as well as its physical significance for the evolution of the shear tensor and expansion scalar are also explored. Finally, we discuss a special case for dust with cosmological constant. |
gr-qc/9411043 | Sathyaprakash | B. S. Sathyaprakash | Filtering post-Newtonian gravitational waves from coalescing binaries | 5 pages, revtex, 2 figures available upon request | Phys.Rev.D50:7111-7115,1994 | 10.1103/PhysRevD.50.R7111 | IUCAA-18/94 | gr-qc | null | Gravitational waves from inspiralling binaries are expected to be detected
using a data analysis technique known as {\it matched filtering.} This
technique is applicable whenever the form of the signal is known accurately.
Though we know the form of the signal precisely, we will not know {\it a
priori} its parameters. Hence it is essential to filter the raw output through
a host of search templates each corresponding to different values of the
parameters. The number of search templates needed in detecting the Newtonian
waveform characterized by three independent parameters is itself several
thousands. With the inclusion of post-Newtonian corrections the inspiral
waveform will have four independent parameters and this, it was thought, would
lead to an increase in the number of filters by several orders of
magnitude---an unfavorable feature since it would drastically slow down data
analysis. In this paper I show that by a judicious choice of signal parameters
we can work, even when the first post-Newtonian corrections are included, with
as many number of parameters as in the Newtonian case. In other words I
demonstrate that the effective dimensionality of the signal parameter space
does not change when first post-Newtonian corrections are taken into account.
| [
{
"created": "Tue, 15 Nov 1994 19:33:35 GMT",
"version": "v1"
}
] | 2010-01-06 | [
[
"Sathyaprakash",
"B. S.",
""
]
] | Gravitational waves from inspiralling binaries are expected to be detected using a data analysis technique known as {\it matched filtering.} This technique is applicable whenever the form of the signal is known accurately. Though we know the form of the signal precisely, we will not know {\it a priori} its parameters. Hence it is essential to filter the raw output through a host of search templates each corresponding to different values of the parameters. The number of search templates needed in detecting the Newtonian waveform characterized by three independent parameters is itself several thousands. With the inclusion of post-Newtonian corrections the inspiral waveform will have four independent parameters and this, it was thought, would lead to an increase in the number of filters by several orders of magnitude---an unfavorable feature since it would drastically slow down data analysis. In this paper I show that by a judicious choice of signal parameters we can work, even when the first post-Newtonian corrections are included, with as many number of parameters as in the Newtonian case. In other words I demonstrate that the effective dimensionality of the signal parameter space does not change when first post-Newtonian corrections are taken into account. |
gr-qc/0008055 | Burinskii A. Ya. | Alexander Burinskii (Russian Academy of Sciences, Moscow) and Giulio
Magli (Dipartimento di Matematica del Politecnico di Milano) | Twisting Lightlike Solutions of the Kerr-Schild Class | 4 pages, Latex, talk given at the session GT4 of the MG9 Meeting (
Rome, 2-9 July, 2000), submitted to the Proceedings of MG9 | null | null | null | gr-qc hep-ph | null | Using a complex representation of the Debney-Kerr-Schild (DKS) solutions and
the Kerr theorem we give a method to construct boosted Kerr geometries. In the
ultrarelativistic case this method yelds twisting solutions having, contrary to
the known pp-wave limiting solutions, a non-zero value of the total angular
momentum. The solutions show that twist plays a crucial role in removing
singularity and smoothing shock wave in the ultrarelativistic limit. Two
different physical situations are discussed.
| [
{
"created": "Tue, 22 Aug 2000 12:41:47 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Burinskii",
"Alexander",
"",
"Russian Academy of Sciences, Moscow"
],
[
"Magli",
"Giulio",
"",
"Dipartimento di Matematica del Politecnico di Milano"
]
] | Using a complex representation of the Debney-Kerr-Schild (DKS) solutions and the Kerr theorem we give a method to construct boosted Kerr geometries. In the ultrarelativistic case this method yelds twisting solutions having, contrary to the known pp-wave limiting solutions, a non-zero value of the total angular momentum. The solutions show that twist plays a crucial role in removing singularity and smoothing shock wave in the ultrarelativistic limit. Two different physical situations are discussed. |
1510.01183 | Otakar Svitek | T. Tahamtan and O. Svitek | Robinson--Trautman solution with nonlinear electrodynamics | 7 figures, to appear in EPJC | Eur. Phys. J. C 76 (2016) 335 | 10.1140/epjc/s10052-016-4175-9 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Explicit Robinson--Trautman solutions with electromagnetic field satisfying
nonlinear field equations are derived and analyzed. The solutions are generated
from the spherically symmetric ones. In all cases the electromagnetic field
singularity is removed while the gravitational one persists. The models
resolving curvature singularity were not possible to generalize to
Robinson--Trautman geometry indicating that the removal of singularity in
associated spherically symmetric case is just a consequence of high symmetry.
We show that the solutions are generally of algebraic type II but reduce to
type D in spherical symmetry. Asymptotically they tend to the spherically
symmetric case as well.
| [
{
"created": "Mon, 5 Oct 2015 15:16:05 GMT",
"version": "v1"
},
{
"created": "Fri, 20 May 2016 17:37:16 GMT",
"version": "v2"
},
{
"created": "Wed, 1 Jun 2016 17:28:10 GMT",
"version": "v3"
}
] | 2016-08-26 | [
[
"Tahamtan",
"T.",
""
],
[
"Svitek",
"O.",
""
]
] | Explicit Robinson--Trautman solutions with electromagnetic field satisfying nonlinear field equations are derived and analyzed. The solutions are generated from the spherically symmetric ones. In all cases the electromagnetic field singularity is removed while the gravitational one persists. The models resolving curvature singularity were not possible to generalize to Robinson--Trautman geometry indicating that the removal of singularity in associated spherically symmetric case is just a consequence of high symmetry. We show that the solutions are generally of algebraic type II but reduce to type D in spherical symmetry. Asymptotically they tend to the spherically symmetric case as well. |
1204.6709 | S. I. Kruglov | S. I. Kruglov | On exponential modified gravity | 20 pages, 9 figures, changed title, extended version, added a
section, figures and references, to be published in IJMPA | Int. J. Mod. Phys.A, Vol.28 (2013), 13501194 | 10.1142/S0217751X13501194 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A modified theory of gravity with the function $F(R) = R\exp(\alpha R)$
instead of Ricci scalar $R$ in the Einstein$-$Hilbert action is considered and
analyzed. The action of the model is converted into Einstein$-$Hilbert action
at small value of the parameter $\alpha$. From local tests we obtain a bound on
the parameter $\alpha\leq 10^{-6}$ cm$^2$. The Jordan and Einstein frames are
investigated and the potential of the scalar field in Einstein's frame is
found. The mass of a scalar degree of freedom as a function of curvature is
obtained. The static solutions of the model are found corresponding to the
Schwarzschild$-$de Sitter space. We show that the de Sitter space is unstable
but a solution with zero curvature is stable. The cosmological parameters of
the model are calculated. It was demonstrated that the model passes the matter
stability test.
| [
{
"created": "Fri, 27 Apr 2012 18:59:13 GMT",
"version": "v1"
},
{
"created": "Fri, 16 Aug 2013 15:23:39 GMT",
"version": "v2"
}
] | 2013-09-30 | [
[
"Kruglov",
"S. I.",
""
]
] | A modified theory of gravity with the function $F(R) = R\exp(\alpha R)$ instead of Ricci scalar $R$ in the Einstein$-$Hilbert action is considered and analyzed. The action of the model is converted into Einstein$-$Hilbert action at small value of the parameter $\alpha$. From local tests we obtain a bound on the parameter $\alpha\leq 10^{-6}$ cm$^2$. The Jordan and Einstein frames are investigated and the potential of the scalar field in Einstein's frame is found. The mass of a scalar degree of freedom as a function of curvature is obtained. The static solutions of the model are found corresponding to the Schwarzschild$-$de Sitter space. We show that the de Sitter space is unstable but a solution with zero curvature is stable. The cosmological parameters of the model are calculated. It was demonstrated that the model passes the matter stability test. |
1305.0308 | Alain Ulacia Rey | I. Delgado Gaspar, A. Perez Martinez, Roberto A. Sussman and A. Ulacia
Rey | Gravitational collapse of a magnetized fermion gas with finite
temperature | 9 pages, 7 figures. arXiv admin note: substantial text overlap with
arXiv:1211.5980 | European Journal of Physics C, 73, 2502, (2013) | 10.1140/epjc/s10052-013-2502-y | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We examine the dynamics of a self--gravitating magnetized electron gas at
finite temperature near the collapsing singularity of a Bianchi-I spacetime.
Considering a general and appropriate and physically motivated initial
conditions, we transform Einstein--Maxwell field equations into a complete and
self--consistent dynamical system amenable for numerical work. The resulting
numerical solutions reveal the gas collapsing into both, isotropic
("point-like") and anisotropic ("cigar-like") singularities, depending on the
initial intensity of the magnetic field. We provide a thorough study of the
near collapse behavior and interplay of all relevant state and kinematic
variables: temperature, expansion scalar, shear scalar, magnetic field,
magnetization and energy density. A significant qualitative difference in the
behavior of the gas emerges in the temperature range $\hbox{T}
sim10^{4}\hbox{K}$ and $\hbox{T}\sim 10^{7}\hbox{K}$.
| [
{
"created": "Wed, 1 May 2013 22:31:28 GMT",
"version": "v1"
}
] | 2015-06-15 | [
[
"Gaspar",
"I. Delgado",
""
],
[
"Martinez",
"A. Perez",
""
],
[
"Sussman",
"Roberto A.",
""
],
[
"Rey",
"A. Ulacia",
""
]
] | We examine the dynamics of a self--gravitating magnetized electron gas at finite temperature near the collapsing singularity of a Bianchi-I spacetime. Considering a general and appropriate and physically motivated initial conditions, we transform Einstein--Maxwell field equations into a complete and self--consistent dynamical system amenable for numerical work. The resulting numerical solutions reveal the gas collapsing into both, isotropic ("point-like") and anisotropic ("cigar-like") singularities, depending on the initial intensity of the magnetic field. We provide a thorough study of the near collapse behavior and interplay of all relevant state and kinematic variables: temperature, expansion scalar, shear scalar, magnetic field, magnetization and energy density. A significant qualitative difference in the behavior of the gas emerges in the temperature range $\hbox{T} sim10^{4}\hbox{K}$ and $\hbox{T}\sim 10^{7}\hbox{K}$. |
1311.6509 | Jan Steinhoff | Sayan Chakrabarti, T\'erence Delsate, Norman G\"urlebeck, Jan
Steinhoff | I-Q relation for rapidly rotating neutron stars | RevTeX, 6 pages, 5 figures, v2: overall improvement of presentation,
extended discussion of prospects for observations, v3: published version | Phys. Rev. Lett. 112, 201102 (2014) | 10.1103/PhysRevLett.112.201102 | null | gr-qc astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a universal relation between moment of inertia and quadrupole
moment of arbitrarily fast rotating neutron stars. Recent studies suggest that
this relation breaks down for fast rotation. We find that it is still universal
among various suggested equations of state for constant values of certain
dimensionless parameters characterizing the magnitude of rotation. One of these
parameters includes the neutron star radius, leading to a new universal
relation expressing the radius through the mass, frequency, and spin parameter.
This can become a powerful tool for radius measurements.
| [
{
"created": "Mon, 25 Nov 2013 22:47:43 GMT",
"version": "v1"
},
{
"created": "Fri, 14 Feb 2014 18:54:43 GMT",
"version": "v2"
},
{
"created": "Fri, 27 Jun 2014 09:31:55 GMT",
"version": "v3"
}
] | 2014-06-30 | [
[
"Chakrabarti",
"Sayan",
""
],
[
"Delsate",
"Térence",
""
],
[
"Gürlebeck",
"Norman",
""
],
[
"Steinhoff",
"Jan",
""
]
] | We consider a universal relation between moment of inertia and quadrupole moment of arbitrarily fast rotating neutron stars. Recent studies suggest that this relation breaks down for fast rotation. We find that it is still universal among various suggested equations of state for constant values of certain dimensionless parameters characterizing the magnitude of rotation. One of these parameters includes the neutron star radius, leading to a new universal relation expressing the radius through the mass, frequency, and spin parameter. This can become a powerful tool for radius measurements. |
1307.4448 | Barun Majumder | Barun Majumder | f(R) in Holographic and Agegraphic Dark Energy Models and the
Generalized Uncertainty Principle | To appear in Advances in High Energy Physics | Advances in High Energy Physics, Volume 2013 (2013), Article ID
143195, 11 pages | 10.1155/2013/143195 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We studied a unified approach with the holographic, new agegraphic and the
$f(R)$ dark energy model to construct the form of $f(R)$ which in general
responsible for the curvature driven explanation of the very early inflation
along with presently observed late time acceleration. We considered the
generalized uncertainty principle in our approach which incorporated the
corrections in the entropy area relation and thereby modified the energy
densities for the cosmological dark energy models considered. We found that
holographic and new agegraphic $f(R)$ gravity models can behave like phantom or
quintessence models in the spatially flat FRW universe. We also found a
distinct term in the form of $f(R)$ which goes as $R^{\frac{3}{2}}$ due to the
consideration of the GUP modified energy densities. Although the presence of
this term in the action can have its importance in explaining the early
inflationary scenario but Capozziello {\it et.al.} recently showed that $f(R)
\sim R^{\frac{3}{2}}$ leads to an accelerated expansion, {\it i.e.}, a negative
value for the deceleration parameter $q$ which fit well with SNeIa and WMAP
data.
| [
{
"created": "Tue, 16 Jul 2013 23:18:32 GMT",
"version": "v1"
}
] | 2013-11-05 | [
[
"Majumder",
"Barun",
""
]
] | We studied a unified approach with the holographic, new agegraphic and the $f(R)$ dark energy model to construct the form of $f(R)$ which in general responsible for the curvature driven explanation of the very early inflation along with presently observed late time acceleration. We considered the generalized uncertainty principle in our approach which incorporated the corrections in the entropy area relation and thereby modified the energy densities for the cosmological dark energy models considered. We found that holographic and new agegraphic $f(R)$ gravity models can behave like phantom or quintessence models in the spatially flat FRW universe. We also found a distinct term in the form of $f(R)$ which goes as $R^{\frac{3}{2}}$ due to the consideration of the GUP modified energy densities. Although the presence of this term in the action can have its importance in explaining the early inflationary scenario but Capozziello {\it et.al.} recently showed that $f(R) \sim R^{\frac{3}{2}}$ leads to an accelerated expansion, {\it i.e.}, a negative value for the deceleration parameter $q$ which fit well with SNeIa and WMAP data. |
1209.2695 | Plamen Fiziev | Plamen P. Fiziev | Withholding Potentials, Absence of Ghosts and Relationship between
Minimal Dilatonic Gravity and f(R) Theories | LaTeX file, 13 pages, 4 figures. Typos corrected. A slightly
shortened version: the examples of f(R) models which are not equivalent to
the MDG removed together with the corresponding figures (See version 2.).
Some remarks removed or replaced by new ones. To appear in Physical Review D | Physical Review D 87, 044053 (2013) | 10.1103/PhysRevD.87.044053 | SU TH-5-09-2012 | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the relation between Minimal Dilatonic Gravity (MDG) and f(R)
theories of gravity and establish strict conditions for their {\em global}
equivalence. Such equivalence takes place only for a certain class of
cosmological potentials, dubbed here {\em withholding potentials}, since they
prevent change of the sign of dilaton $\Phi$. The withholding property ensures
the attractive character of gravity, as well as absence of ghosts and a tachyon
in the gravi-dilaton sector and yields certain asymptotic of the admissible
functions $f(R)$. Large classes of withholding cosmological potentials and
functions $f(R)$ are found and described in detail. It is shown that the
popular choices of $f(R)$ functions are not withholding ones. The particle
content of the gravi-dilaton sector is found using perturbation theory around
de Sitter vacuum of MDG. The graviton remains massless, since it obeys
conformal invariant field equation in the de Sitter space-time. The $R/6$ term
in the conformal invariant wave operator introduces a very small mass scale
$m_{R} \approx 1.5 \times 10^{-38} m_e$, $m_e$ being the mass of the electron.
The mass of the dilaton is much larger: $m\gtrapprox 10^{29} m_{R}$. Two new
phenomena: scalaron waves and induction of gravitational waves by the scalaron
field are discussed using the derived wave equations for scalaron and graviton.
The MDG and f(R) theories are shown to predict physical deviations from GR.
Seemingly, the MDG and f(R) theories, when globally equivalent, offer a unified
description of dark energy and dark matter.
| [
{
"created": "Wed, 12 Sep 2012 19:23:59 GMT",
"version": "v1"
},
{
"created": "Sun, 7 Oct 2012 13:53:03 GMT",
"version": "v2"
},
{
"created": "Sat, 23 Feb 2013 16:46:43 GMT",
"version": "v3"
}
] | 2013-03-04 | [
[
"Fiziev",
"Plamen P.",
""
]
] | We study the relation between Minimal Dilatonic Gravity (MDG) and f(R) theories of gravity and establish strict conditions for their {\em global} equivalence. Such equivalence takes place only for a certain class of cosmological potentials, dubbed here {\em withholding potentials}, since they prevent change of the sign of dilaton $\Phi$. The withholding property ensures the attractive character of gravity, as well as absence of ghosts and a tachyon in the gravi-dilaton sector and yields certain asymptotic of the admissible functions $f(R)$. Large classes of withholding cosmological potentials and functions $f(R)$ are found and described in detail. It is shown that the popular choices of $f(R)$ functions are not withholding ones. The particle content of the gravi-dilaton sector is found using perturbation theory around de Sitter vacuum of MDG. The graviton remains massless, since it obeys conformal invariant field equation in the de Sitter space-time. The $R/6$ term in the conformal invariant wave operator introduces a very small mass scale $m_{R} \approx 1.5 \times 10^{-38} m_e$, $m_e$ being the mass of the electron. The mass of the dilaton is much larger: $m\gtrapprox 10^{29} m_{R}$. Two new phenomena: scalaron waves and induction of gravitational waves by the scalaron field are discussed using the derived wave equations for scalaron and graviton. The MDG and f(R) theories are shown to predict physical deviations from GR. Seemingly, the MDG and f(R) theories, when globally equivalent, offer a unified description of dark energy and dark matter. |
2107.01935 | Sai Wang | Sai Wang, Valeri Vardanyan, Kazunori Kohri | Probing primordial black holes with anisotropies in stochastic
gravitational-wave background | Version accepted for publication in PRD, 10 pages, 6 figures | Phys. Rev. D 106, 123511 (2022) | 10.1103/PhysRevD.106.123511 | KEK-TH-2410, KEK-Cosmo-0286, KEK-QUP-2022-0016 | gr-qc astro-ph.CO astro-ph.HE | http://creativecommons.org/licenses/by-nc-nd/4.0/ | Primordial black holes, if considered to constitute a significant fraction of
cold dark matter, trace the inhomogeneous large-scale structure of the
Universe. Consequently, the stochastic gravitational-wave background,
originating from incoherent superposition of unresolved signals emitted by
primordial black hole binaries, is expected to display anisotropies across the
sky. In this work, we investigate the angular correlations of such anisotropies
for the first time and demonstrate their difference from the analogous signal
produced by astrophysical black hole binaries. We carefully evaluate the
associated uncertainties due to shot-noise and cosmic variance, and demonstrate
that the studied signal in the low-frequency regime can be differentiated from
the signal of astrophysical origin. Our results are particularly promising in
the stellar mass-range, where the identification of the merger origin has been
particularly challenging.
| [
{
"created": "Mon, 5 Jul 2021 11:03:22 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Apr 2022 11:19:44 GMT",
"version": "v2"
},
{
"created": "Sun, 4 Dec 2022 01:33:00 GMT",
"version": "v3"
}
] | 2022-12-22 | [
[
"Wang",
"Sai",
""
],
[
"Vardanyan",
"Valeri",
""
],
[
"Kohri",
"Kazunori",
""
]
] | Primordial black holes, if considered to constitute a significant fraction of cold dark matter, trace the inhomogeneous large-scale structure of the Universe. Consequently, the stochastic gravitational-wave background, originating from incoherent superposition of unresolved signals emitted by primordial black hole binaries, is expected to display anisotropies across the sky. In this work, we investigate the angular correlations of such anisotropies for the first time and demonstrate their difference from the analogous signal produced by astrophysical black hole binaries. We carefully evaluate the associated uncertainties due to shot-noise and cosmic variance, and demonstrate that the studied signal in the low-frequency regime can be differentiated from the signal of astrophysical origin. Our results are particularly promising in the stellar mass-range, where the identification of the merger origin has been particularly challenging. |
1507.07367 | Jake Dunn | Jake Dunn and Claude Warnick | The Klein-Gordon equation on the toric adS-Schwarzschild black hole | 32 pages, 1 figure | null | 10.1088/0264-9381/33/12/125010 | null | gr-qc math-ph math.AP math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the Klein-Gordon equation on the exterior of the toric anti
de-Sitter Schwarzschild black hole with Dirichlet, Neumann and Robin boundary
conditions at $\mathcal{I}$. We define a non-degenerate energy for the equation
which controls the renormalised $H^1$ norm of the field. We then establish both
decay and integrated decay of this energy through vector field methods. Finally
we demonstrate the necessity of `losing a derivative' in the integrated energy
estimate through the construction of a Gaussian beam staying in the exterior of
the event horizon for arbitrary long co-ordinate time.
| [
{
"created": "Mon, 27 Jul 2015 11:20:08 GMT",
"version": "v1"
},
{
"created": "Thu, 12 Nov 2015 11:14:41 GMT",
"version": "v2"
}
] | 2016-05-25 | [
[
"Dunn",
"Jake",
""
],
[
"Warnick",
"Claude",
""
]
] | We consider the Klein-Gordon equation on the exterior of the toric anti de-Sitter Schwarzschild black hole with Dirichlet, Neumann and Robin boundary conditions at $\mathcal{I}$. We define a non-degenerate energy for the equation which controls the renormalised $H^1$ norm of the field. We then establish both decay and integrated decay of this energy through vector field methods. Finally we demonstrate the necessity of `losing a derivative' in the integrated energy estimate through the construction of a Gaussian beam staying in the exterior of the event horizon for arbitrary long co-ordinate time. |
1907.01751 | Maksat Temirkhan Sergey | Michael R. R. Good, Maksat Temirkhan, Thomas Oikonomou | Stationary Worldline Power Distributions | 27 pages, 68 figures, The MSc thesis arXiv:1904.12916 is based on
this work | International Journal of Theoretical Physics, (2019), 1-27 | 10.1007/s10773-019-04176-7 | null | gr-qc physics.class-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A worldline with a time-independent spectrum is called stationary. Such
worldlines are arguably the most simple motions in physics. Barring the
trivially static motion, the non-trivial worldlines are uniformly accelerated.
As such, a point charge moving along a stationary worldline will emit constant
radiative power. The angular distribution, maximum angle scaling and Thomas
precession of this power is found for all stationary worldlines including those
with torsion and hypertorsion.
| [
{
"created": "Wed, 3 Jul 2019 06:06:29 GMT",
"version": "v1"
}
] | 2019-07-04 | [
[
"Good",
"Michael R. R.",
""
],
[
"Temirkhan",
"Maksat",
""
],
[
"Oikonomou",
"Thomas",
""
]
] | A worldline with a time-independent spectrum is called stationary. Such worldlines are arguably the most simple motions in physics. Barring the trivially static motion, the non-trivial worldlines are uniformly accelerated. As such, a point charge moving along a stationary worldline will emit constant radiative power. The angular distribution, maximum angle scaling and Thomas precession of this power is found for all stationary worldlines including those with torsion and hypertorsion. |
gr-qc/9903025 | T. R. Mongan | T. R. Mongan | Quantum mechanics forbids an initial or final singularity in a closed
FRW universe | 2 pages | Gen.Rel.Grav. 31 (1999) 1429-1430 | 10.1023/A:1026797413078 | null | gr-qc | null | The existence of singularities in a closed FRW universe depends on the
assumption that general relativity is valid for distances less than the Planck
length. However, stationary state wave functions of the Schrodinger equation
for a closed radiation-dominated FRW universe derived by Elbaz et al (General
Relativity and Gravitation 29, 481, 1997) are zero at zero radius of curvature.
Thus, even if general relativity is assumed valid at distances less than the
Planck length, quantum mechanics seems to forbid singularities in a closed FRW
universe.
| [
{
"created": "Sun, 7 Mar 1999 20:36:34 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Mongan",
"T. R.",
""
]
] | The existence of singularities in a closed FRW universe depends on the assumption that general relativity is valid for distances less than the Planck length. However, stationary state wave functions of the Schrodinger equation for a closed radiation-dominated FRW universe derived by Elbaz et al (General Relativity and Gravitation 29, 481, 1997) are zero at zero radius of curvature. Thus, even if general relativity is assumed valid at distances less than the Planck length, quantum mechanics seems to forbid singularities in a closed FRW universe. |
gr-qc/0306045 | Cenalo Vaz | Cenalo Vaz (Univ. Algarve), Louis Witten (Univ. Cincinnati) and T.P.
Singh (TIFR) | Exact Quantum State of Collapse and Black Hole Radiation | 6 pages, no figures, RevTeX4. Portions have been rewritten to clarify
the contents. The results remain unchanged. Version to appear in Phys. Rev. D | Phys.Rev. D69 (2004) 104029 | 10.1103/PhysRevD.69.104029 | Ualg-03/03 | gr-qc hep-th | null | We construct an exact quantum gravitational state describing the collapse of
an inhomogeneous spherical dust cloud using a lattice regularization of the
Wheeler-DeWitt equation. In the semiclassical approximation around a black
hole, this state describes Hawking radiation. We show that the leading quantum
gravitational correction to Hawking radiation renders the spectrum non-thermal.
| [
{
"created": "Wed, 11 Jun 2003 11:52:49 GMT",
"version": "v1"
},
{
"created": "Wed, 4 Feb 2004 19:26:45 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Vaz",
"Cenalo",
"",
"Univ. Algarve"
],
[
"Witten",
"Louis",
"",
"Univ. Cincinnati"
],
[
"Singh",
"T. P.",
"",
"TIFR"
]
] | We construct an exact quantum gravitational state describing the collapse of an inhomogeneous spherical dust cloud using a lattice regularization of the Wheeler-DeWitt equation. In the semiclassical approximation around a black hole, this state describes Hawking radiation. We show that the leading quantum gravitational correction to Hawking radiation renders the spectrum non-thermal. |
1904.09509 | \.Izzet Sakall{\i} | Ali \"Ovg\"un, \.Izzet Sakall{\i}, and Halil Mutuk | Quasinormal modes of dS and AdS Black Holes: Feedforward neural network
method | Accepted for Publication in IJGMMP | Int.J.Geom.Meth.Mod.Phys. Vol. 18, No. 10, 2150154 (2021) | 10.1142/S0219887821501541 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we show how the quasinormal modes (QNMs) arise from the
perturbations of massive scalar fields propagating in the curved background by
using the artificial neural networks. To this end, we architect a special
algorithm for the feedforward neural network method (FNNM) to compute the QNMs
complying with the certain types of boundary conditions. To test the
reliability of the method, we consider two black hole spacetimes whose QNMs are
well-known: $4D$ pure de Sitter (dS) and five-dimensional Schwarzschild anti-de
Sitter (AdS) black holes. Using the FNNM, the QNMs of are computed numerically.
It is shown that the obtained QNMs via the FNNM are in good agreement with
their former QNM results resulting from the other methods. Therefore, our
method of finding the QNMs can be used for other curved spacetimes that obey
the same boundary conditions.
| [
{
"created": "Sat, 20 Apr 2019 22:32:28 GMT",
"version": "v1"
},
{
"created": "Sun, 16 May 2021 17:20:36 GMT",
"version": "v2"
}
] | 2022-03-22 | [
[
"Övgün",
"Ali",
""
],
[
"Sakallı",
"İzzet",
""
],
[
"Mutuk",
"Halil",
""
]
] | In this paper, we show how the quasinormal modes (QNMs) arise from the perturbations of massive scalar fields propagating in the curved background by using the artificial neural networks. To this end, we architect a special algorithm for the feedforward neural network method (FNNM) to compute the QNMs complying with the certain types of boundary conditions. To test the reliability of the method, we consider two black hole spacetimes whose QNMs are well-known: $4D$ pure de Sitter (dS) and five-dimensional Schwarzschild anti-de Sitter (AdS) black holes. Using the FNNM, the QNMs of are computed numerically. It is shown that the obtained QNMs via the FNNM are in good agreement with their former QNM results resulting from the other methods. Therefore, our method of finding the QNMs can be used for other curved spacetimes that obey the same boundary conditions. |
1707.07200 | Ouali Taoufik | Mariam Bouhmadi-L\'opez, Ahmed Errahmani, Taoufik Ouali and Yaser
Tavakoli | More on the holographic Ricci dark energy model: smoothing Rips through
interaction effects? | 10 pages, Shortened and improved version | Eur. Phys. J. C (2018) 78:330 | 10.1140/epjc/s10052-018-5773-5 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The background cosmological dynamics of the late Universe is analysed on the
framework of a dark energy model described by an holographic Ricci dark energy
component. Several kind of interactions between the dark energy and the dark
matter components are considered herein. We solve the background cosmological
dynamics for the different choices of interactions with the aim to analyse not
only the current evolution of the universe but also its asymptotic behaviour
and, in particular, possible future singularities removal. We show that in most
of the cases, the Big Rip singularity, a finger print of this model in absence
of an interaction between the dark sectors, is substituted by a de Sitter or a
Minkowski state. Most importantly, we found two new {\textit{ future}} bouncing
solutions leading to two possible asymptotic behaviours, we named Little Bang
and Little Sibling of the Big Bang. At a Little Bang, as the size of the
universe shrinks to zero in an infinite cosmic time, the Hubble rate and its
cosmic time derivative blow up. In addition, at a Little sibling of the Big
Bang, as the size of the universe shrinks to zero in an infinite cosmic time,
the Hubble rate blows up but its cosmic time derivative is finite. These two
abrupt events can happen as well in the past.
| [
{
"created": "Sat, 22 Jul 2017 18:01:58 GMT",
"version": "v1"
},
{
"created": "Mon, 2 Apr 2018 23:17:58 GMT",
"version": "v2"
},
{
"created": "Thu, 3 May 2018 09:45:09 GMT",
"version": "v3"
}
] | 2018-05-09 | [
[
"Bouhmadi-López",
"Mariam",
""
],
[
"Errahmani",
"Ahmed",
""
],
[
"Ouali",
"Taoufik",
""
],
[
"Tavakoli",
"Yaser",
""
]
] | The background cosmological dynamics of the late Universe is analysed on the framework of a dark energy model described by an holographic Ricci dark energy component. Several kind of interactions between the dark energy and the dark matter components are considered herein. We solve the background cosmological dynamics for the different choices of interactions with the aim to analyse not only the current evolution of the universe but also its asymptotic behaviour and, in particular, possible future singularities removal. We show that in most of the cases, the Big Rip singularity, a finger print of this model in absence of an interaction between the dark sectors, is substituted by a de Sitter or a Minkowski state. Most importantly, we found two new {\textit{ future}} bouncing solutions leading to two possible asymptotic behaviours, we named Little Bang and Little Sibling of the Big Bang. At a Little Bang, as the size of the universe shrinks to zero in an infinite cosmic time, the Hubble rate and its cosmic time derivative blow up. In addition, at a Little sibling of the Big Bang, as the size of the universe shrinks to zero in an infinite cosmic time, the Hubble rate blows up but its cosmic time derivative is finite. These two abrupt events can happen as well in the past. |
0710.4362 | Gregory Mendell | Gregory Mendell, Karl Wette | Using generalized PowerFlux methods to estimate the parameters of
periodic gravitational waves | 8 pages, presented at Amalid7, Sydney, Australia (July 2007), fixed
minor typos and clarified discussion to match published CQG version; updated
references | Class.Quant.Grav.25:114044,2008 | 10.1088/0264-9381/25/11/114044 | null | gr-qc | null | We investigate methods to estimate the parameters of the gravitational-wave
signal from a spinning neutron star using Fourier transformed segments of the
strain response from an interferometric detector. Estimating the parameters
from the power, we find generalizations of the PowerFlux method. Using
simulated elliptically polarized signals injected into Gaussian noise, we apply
the generalized methods to estimate the squared amplitudes of the plus and
cross polarizations (and, in the most general case, the polarization angle),
and test the relative detection efficiencies of the various methods.
| [
{
"created": "Tue, 23 Oct 2007 23:54:14 GMT",
"version": "v1"
},
{
"created": "Fri, 16 May 2008 00:06:49 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Mendell",
"Gregory",
""
],
[
"Wette",
"Karl",
""
]
] | We investigate methods to estimate the parameters of the gravitational-wave signal from a spinning neutron star using Fourier transformed segments of the strain response from an interferometric detector. Estimating the parameters from the power, we find generalizations of the PowerFlux method. Using simulated elliptically polarized signals injected into Gaussian noise, we apply the generalized methods to estimate the squared amplitudes of the plus and cross polarizations (and, in the most general case, the polarization angle), and test the relative detection efficiencies of the various methods. |
1710.02865 | Heling Deng | Heling Deng and Alexander Vilenkin | Primordial black hole formation by vacuum bubbles | 39 pages, 12 figures | null | 10.1088/1475-7516/2017/12/044 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Vacuum bubbles may nucleate during the inflationary epoch and expand,
reaching relativistic speeds. After inflation ends, the bubbles are quickly
slowed down, transferring their momentum to a shock wave that propagates
outwards in the radiation background. The ultimate fate of the bubble depends
on its size. Bubbles smaller than certain critical size collapse to ordinary
black holes, while in the supercritical case the bubble interior inflates,
forming a baby universe, which is connected to the exterior region by a
wormhole. The wormhole then closes up, turning into two black holes at its two
mouths. We use numerical simulations to find the masses of black holes formed
in this scenario, both in subcritical and supercritical regime. The resulting
mass spectrum is extremely broad, ranging over many orders of magnitude. For
some parameter values, these black holes can serve as seeds for supermassive
black holes and may account for LIGO observations.
| [
{
"created": "Sun, 8 Oct 2017 18:04:57 GMT",
"version": "v1"
},
{
"created": "Sat, 10 Mar 2018 05:12:50 GMT",
"version": "v2"
}
] | 2018-03-13 | [
[
"Deng",
"Heling",
""
],
[
"Vilenkin",
"Alexander",
""
]
] | Vacuum bubbles may nucleate during the inflationary epoch and expand, reaching relativistic speeds. After inflation ends, the bubbles are quickly slowed down, transferring their momentum to a shock wave that propagates outwards in the radiation background. The ultimate fate of the bubble depends on its size. Bubbles smaller than certain critical size collapse to ordinary black holes, while in the supercritical case the bubble interior inflates, forming a baby universe, which is connected to the exterior region by a wormhole. The wormhole then closes up, turning into two black holes at its two mouths. We use numerical simulations to find the masses of black holes formed in this scenario, both in subcritical and supercritical regime. The resulting mass spectrum is extremely broad, ranging over many orders of magnitude. For some parameter values, these black holes can serve as seeds for supermassive black holes and may account for LIGO observations. |
1305.5461 | Bayram Tekin | Ibrahim Gullu, Bayram Tekin | Spin-Spin Interactions in Massive Gravity and Higher Derivative Gravity
Theories | 7 pages, title has changed, derivations of the results incorporated
to the Appendix. Matches the published version in Physics Letters B | Physics Letters B Volume 728 (2014) 268 | 10.1016/j.physletb.2013.11.064 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that, in the weak field limit, at large separations, in sharp
contrast to General Relativity (GR), all massive gravity theories predict
distance-dependent spin alignments for spinning objects. For all separations GR
requires anti-parallel spin orientations with spins pointing along the line
joining the sources. Hence total spin is minimized in GR. On the other hand,
while massive gravity at small separations ($m_gr \le1.62$) gives the same
result as GR, for large separations ($m_gr>1.62$) the spins become parallel to
each other and perpendicular to the line joining the objects. Namely, the
potential energy is minimized when the total spin is maximized in massive
gravity for large separations. We also compute the spin-spin interactions in
quadratic gravity theories and find that while at large separations GR result
is intact, at small separations, spins become perpendicular to the line joining
sources and anti-parallel to each other.
| [
{
"created": "Thu, 23 May 2013 15:37:28 GMT",
"version": "v1"
},
{
"created": "Mon, 16 Sep 2013 15:11:09 GMT",
"version": "v2"
},
{
"created": "Tue, 5 Nov 2013 14:43:42 GMT",
"version": "v3"
},
{
"created": "Wed, 11 Dec 2013 13:12:23 GMT",
"version": "v4"
}
] | 2014-01-17 | [
[
"Gullu",
"Ibrahim",
""
],
[
"Tekin",
"Bayram",
""
]
] | We show that, in the weak field limit, at large separations, in sharp contrast to General Relativity (GR), all massive gravity theories predict distance-dependent spin alignments for spinning objects. For all separations GR requires anti-parallel spin orientations with spins pointing along the line joining the sources. Hence total spin is minimized in GR. On the other hand, while massive gravity at small separations ($m_gr \le1.62$) gives the same result as GR, for large separations ($m_gr>1.62$) the spins become parallel to each other and perpendicular to the line joining the objects. Namely, the potential energy is minimized when the total spin is maximized in massive gravity for large separations. We also compute the spin-spin interactions in quadratic gravity theories and find that while at large separations GR result is intact, at small separations, spins become perpendicular to the line joining sources and anti-parallel to each other. |
1205.0930 | Olivier Besida | Olivier Besida (SPP) | The road toward a general relativistic metric inside the Earth and its
effect on neutrino travel from CERN to GRAN-SASSO Laboratory | 26 pages | null | null | null | gr-qc hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In a first attempt to describe the effect on neutrino travel inside the Earth
caused by general relativity in the case of a dense Earth, we have neglected
the Earth's rotation, the Earth's ellipticity and also the surface terrain
variation, nevertheless we have focused our attention on the density
description of the Earth interior provided by geophysic's models such as PREM.
Assuming a non rotating Earth, the general relativistic effect on neutrino
travelling from CERN to GRAN-SASSO happened to produce a delay of $\delta
t=4.1863 \, picosecond$.
| [
{
"created": "Fri, 4 May 2012 12:15:22 GMT",
"version": "v1"
}
] | 2012-05-07 | [
[
"Besida",
"Olivier",
"",
"SPP"
]
] | In a first attempt to describe the effect on neutrino travel inside the Earth caused by general relativity in the case of a dense Earth, we have neglected the Earth's rotation, the Earth's ellipticity and also the surface terrain variation, nevertheless we have focused our attention on the density description of the Earth interior provided by geophysic's models such as PREM. Assuming a non rotating Earth, the general relativistic effect on neutrino travelling from CERN to GRAN-SASSO happened to produce a delay of $\delta t=4.1863 \, picosecond$. |
1902.08273 | Charles J. Horowitz | C. J. Horowitz, M. A. Papa, and S. Reddy | Gravitational waves from compact dark matter objects in the solar system | 5 pages, 3 figures, Phys. Lett. B in press | Phys. Lett. B 800, 135072 (2020) | 10.1016/j.physletb.2019.135072 | null | gr-qc astro-ph.HE astro-ph.IM hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Dark matter could be composed of compact dark objects (CDOs). A close binary
of CDOs orbiting in the interior of solar system bodies can be a loud source of
gravitational waves (GWs) for the LIGO and VIRGO detectors. We perform the
first search ever for this type of signal and rule out close binaries, with
separations of order 300 m, orbiting near the center of the Sun with GW
frequencies (twice the orbital frequency) between 50 and 550 Hz and CDO masses
above $\approx 10^{-9} M_\odot$. This mass limit is eight orders of magnitude
lower than the mass probed in a LIGO search at extra galactic distances.
| [
{
"created": "Thu, 21 Feb 2019 21:26:22 GMT",
"version": "v1"
},
{
"created": "Tue, 29 Oct 2019 14:33:50 GMT",
"version": "v2"
}
] | 2019-11-18 | [
[
"Horowitz",
"C. J.",
""
],
[
"Papa",
"M. A.",
""
],
[
"Reddy",
"S.",
""
]
] | Dark matter could be composed of compact dark objects (CDOs). A close binary of CDOs orbiting in the interior of solar system bodies can be a loud source of gravitational waves (GWs) for the LIGO and VIRGO detectors. We perform the first search ever for this type of signal and rule out close binaries, with separations of order 300 m, orbiting near the center of the Sun with GW frequencies (twice the orbital frequency) between 50 and 550 Hz and CDO masses above $\approx 10^{-9} M_\odot$. This mass limit is eight orders of magnitude lower than the mass probed in a LIGO search at extra galactic distances. |
2110.11997 | Fabrizio Di Giovanni | Fabrizio Di Giovanni, Nicolas Sanchis-Gual, Pablo Cerd\'a-Dur\'an,
Jos\'e Antonio Font | Can fermion-boson stars reconcile multi-messenger observations of
compact stars? | 9 pages, 7 figures | null | 10.1103/PhysRevD.105.063005 | null | gr-qc astro-ph.HE astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Mixed fermion-boson stars are stable, horizonless, everywhere regular
solutions of the coupled Einstein-(complex, massive) Klein-Gordon-Euler system.
While isolated neutron stars and boson stars are uniquely determined by their
central energy density, mixed configurations conform an extended parameter
space that depends on the combination of the number of fermions and
(ultra-light) bosons. The wider possibilities offered by fermion-boson stars
could help explain the tension in the measurements of neutron star masses and
radii reported in recent multi-messenger observations and nuclear-physics
experiments. In this work we construct equilibrium configurations of mixed
fermion-boson stars with realistic equations of state for the fermionic
component and different percentages of bosonic matter. We show that our
solutions are in excellent agreement with multi-messenger data, including
gravitational-wave events GW170817 and GW190814 and X-ray pulsars PSR
J0030+0451 and PSR J0740+6620, as well as with nuclear physics constraints from
the PREX-2 experiment.
| [
{
"created": "Fri, 22 Oct 2021 18:21:47 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Oct 2021 16:18:02 GMT",
"version": "v2"
}
] | 2022-03-14 | [
[
"Di Giovanni",
"Fabrizio",
""
],
[
"Sanchis-Gual",
"Nicolas",
""
],
[
"Cerdá-Durán",
"Pablo",
""
],
[
"Font",
"José Antonio",
""
]
] | Mixed fermion-boson stars are stable, horizonless, everywhere regular solutions of the coupled Einstein-(complex, massive) Klein-Gordon-Euler system. While isolated neutron stars and boson stars are uniquely determined by their central energy density, mixed configurations conform an extended parameter space that depends on the combination of the number of fermions and (ultra-light) bosons. The wider possibilities offered by fermion-boson stars could help explain the tension in the measurements of neutron star masses and radii reported in recent multi-messenger observations and nuclear-physics experiments. In this work we construct equilibrium configurations of mixed fermion-boson stars with realistic equations of state for the fermionic component and different percentages of bosonic matter. We show that our solutions are in excellent agreement with multi-messenger data, including gravitational-wave events GW170817 and GW190814 and X-ray pulsars PSR J0030+0451 and PSR J0740+6620, as well as with nuclear physics constraints from the PREX-2 experiment. |
2404.16909 | Naman Kumar | Naman Kumar | Relativistic Correction to Black Hole Entropy | null | Gen Relativ Gravit 56, 47 (2024) | 10.1007/s10714-024-03228-6 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we study the relativistic correction to Bekenstein-Hawking
entropy in the canonical ensemble and isothermal-isobaric ensemble and apply it
to the cases of non-rotating BTZ and AdS-Schwarzschild black holes. This is
realized by generalizing the equations obtained using Boltzmann-Gibbs(BG)
statistics with its relativistic generalization, Kaniadakis statistics, or
$\kappa$-statistics. The relativistic corrections are found to be logarithmic
in nature and it is observed that their effect becomes appreciable in the
high-temperature limit suggesting that the entropy corrections must include
these relativistically corrected terms while taking the aforementioned limit.
The non-relativistic corrections are recovered in the $\kappa\rightarrow 0$
limit.
| [
{
"created": "Thu, 25 Apr 2024 13:38:16 GMT",
"version": "v1"
}
] | 2024-04-29 | [
[
"Kumar",
"Naman",
""
]
] | In this paper, we study the relativistic correction to Bekenstein-Hawking entropy in the canonical ensemble and isothermal-isobaric ensemble and apply it to the cases of non-rotating BTZ and AdS-Schwarzschild black holes. This is realized by generalizing the equations obtained using Boltzmann-Gibbs(BG) statistics with its relativistic generalization, Kaniadakis statistics, or $\kappa$-statistics. The relativistic corrections are found to be logarithmic in nature and it is observed that their effect becomes appreciable in the high-temperature limit suggesting that the entropy corrections must include these relativistically corrected terms while taking the aforementioned limit. The non-relativistic corrections are recovered in the $\kappa\rightarrow 0$ limit. |
1405.5863 | Davood Momeni Dr | Davood Momeni, Ratbay Myrzakulov | Cosmological reconstruction of $f(T,\mathcal{T})$ Gravity | references added, Accepted for publication in "International Journal
of Geometric Methods in Modern Physics." | Int.J.Geom.Meth.Mod.Phys. 11 (2014) no.08, 1450077 | 10.1142/S0219887814500777 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Motivated by the newly proposal for gravity as the effect of the torsion
scalar $T$ and trace of the energy momentum tensor $\mathcal{T}$,we investigate
the cosmological reconstruction of different models of the Universe. Our aim
here is to show that how this modified gravity model, $f(T,\mathcal{T})$ is
able to reproduce different epoches of the cosmological history. We explicitly
show that $f(T,\mathcal{T})$ can be reconstructed for $\Lambda $CDM as the most
popular and consistent model. Also we study the mathematical reconstruction of
$f(T,\mathcal{T})$ for a flat cosmological background filled by two fluids
mixture. Such model describes phantom-non-phantom era as well as the purely
phantom cosmology. We extend our investigation to more cosmological models like
perfect fluid,Chaplygin gas and massless scalar field. In each case we obtain
some specific forms of $f(T,\mathcal{T})$. These families of $f(T,\mathcal{T})$
contain arbitrary function of torsion and trace of the energy momentum.
| [
{
"created": "Thu, 8 May 2014 16:02:13 GMT",
"version": "v1"
},
{
"created": "Thu, 29 May 2014 14:42:01 GMT",
"version": "v2"
}
] | 2018-10-09 | [
[
"Momeni",
"Davood",
""
],
[
"Myrzakulov",
"Ratbay",
""
]
] | Motivated by the newly proposal for gravity as the effect of the torsion scalar $T$ and trace of the energy momentum tensor $\mathcal{T}$,we investigate the cosmological reconstruction of different models of the Universe. Our aim here is to show that how this modified gravity model, $f(T,\mathcal{T})$ is able to reproduce different epoches of the cosmological history. We explicitly show that $f(T,\mathcal{T})$ can be reconstructed for $\Lambda $CDM as the most popular and consistent model. Also we study the mathematical reconstruction of $f(T,\mathcal{T})$ for a flat cosmological background filled by two fluids mixture. Such model describes phantom-non-phantom era as well as the purely phantom cosmology. We extend our investigation to more cosmological models like perfect fluid,Chaplygin gas and massless scalar field. In each case we obtain some specific forms of $f(T,\mathcal{T})$. These families of $f(T,\mathcal{T})$ contain arbitrary function of torsion and trace of the energy momentum. |
gr-qc/0110047 | Mark Miller | J. Font, T. Goodale, S. Iyer, M. Miller, L. Rezzolla, E. Seidel, N.
Stergioulas, W. Suen, M. Tobias | Three-dimensional general relativistic hydrodynamics II: long-term
dynamics of single relativistic stars | 19 pages, 17 figures | Phys.Rev. D65 (2002) 084024 | 10.1103/PhysRevD.65.084024 | null | gr-qc astro-ph | null | This is the second in a series of papers on the construction and validation
of a three-dimensional code for the solution of the coupled system of the
Einstein equations and of the general relativistic hydrodynamic equations, and
on the application of this code to problems in general relativistic
astrophysics. In particular, we report on the accuracy of our code in the
long-term dynamical evolution of relativistic stars and on some new physics
results obtained in the process of code testing. The tests involve single
non-rotating stars in stable equilibrium, non-rotating stars undergoing radial
and quadrupolar oscillations, non-rotating stars on the unstable branch of the
equilibrium configurations migrating to the stable branch, non-rotating stars
undergoing gravitational collapse to a black hole, and rapidly rotating stars
in stable equilibrium and undergoing quasi-radial oscillations. The numerical
evolutions have been carried out in full general relativity using different
types of polytropic equations of state using either the rest-mass density only,
or the rest-mass density and the internal energy as independent variables. New
variants of the spacetime evolution and new high resolution shock capturing
(HRSC) treatments based on Riemann solvers and slope limiters have been
implemented and the results compared with those obtained from previous methods.
Finally, we have obtained the first eigenfrequencies of rotating stars in full
general relativity and rapid rotation. A long standing problem, such
frequencies have not been obtained by other methods. Overall, and to the best
of our knowledge, the results presented in this paper represent the most
accurate long-term three-dimensional evolutions of relativistic stars available
to date.
| [
{
"created": "Tue, 9 Oct 2001 15:42:58 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Font",
"J.",
""
],
[
"Goodale",
"T.",
""
],
[
"Iyer",
"S.",
""
],
[
"Miller",
"M.",
""
],
[
"Rezzolla",
"L.",
""
],
[
"Seidel",
"E.",
""
],
[
"Stergioulas",
"N.",
""
],
[
"Suen",
"W.",
""
... | This is the second in a series of papers on the construction and validation of a three-dimensional code for the solution of the coupled system of the Einstein equations and of the general relativistic hydrodynamic equations, and on the application of this code to problems in general relativistic astrophysics. In particular, we report on the accuracy of our code in the long-term dynamical evolution of relativistic stars and on some new physics results obtained in the process of code testing. The tests involve single non-rotating stars in stable equilibrium, non-rotating stars undergoing radial and quadrupolar oscillations, non-rotating stars on the unstable branch of the equilibrium configurations migrating to the stable branch, non-rotating stars undergoing gravitational collapse to a black hole, and rapidly rotating stars in stable equilibrium and undergoing quasi-radial oscillations. The numerical evolutions have been carried out in full general relativity using different types of polytropic equations of state using either the rest-mass density only, or the rest-mass density and the internal energy as independent variables. New variants of the spacetime evolution and new high resolution shock capturing (HRSC) treatments based on Riemann solvers and slope limiters have been implemented and the results compared with those obtained from previous methods. Finally, we have obtained the first eigenfrequencies of rotating stars in full general relativity and rapid rotation. A long standing problem, such frequencies have not been obtained by other methods. Overall, and to the best of our knowledge, the results presented in this paper represent the most accurate long-term three-dimensional evolutions of relativistic stars available to date. |
1407.5058 | J. Navarro-Salas | Adrian del Rio, Jose Navarro-Salas and Francisco Torrenti | Renormalized stress-energy tensor for spin-1/2 fields in expanding
universes | Latex file, 26 pages | Phys Rev D 90 (2014) 084017 | 10.1103/PhysRevD.90.084017 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide an explicit expression for the renormalized expectation value of
the stress-energy tensor of a spin-$1/2$ field in a spatially flat FLRW
universe. Its computation is based on the extension of the adiabatic
regularization method to fermion fields introduced recently in the literature.
The tensor is given in terms of UV-finite integrals in momentum space, which
involve the mode functions that define the quantum state. As illustrative
examples of the method efficiency, we see how to compute the renormalized
energy density and pressure in two interesting cosmological scenarios: a de
Sitter spacetime and a radiation-dominated universe. In the second case, we
explicitly show that the late-time renormalized stress-energy tensor behaves as
that of classical cold matter. We also check that, if we obtain the adiabatic
expansion of the scalar field mode functions with a similar procedure to the
one used for fermions, we recover the well-known WKB-type expansion.
| [
{
"created": "Fri, 18 Jul 2014 17:00:43 GMT",
"version": "v1"
},
{
"created": "Tue, 30 Sep 2014 15:36:22 GMT",
"version": "v2"
}
] | 2021-09-17 | [
[
"del Rio",
"Adrian",
""
],
[
"Navarro-Salas",
"Jose",
""
],
[
"Torrenti",
"Francisco",
""
]
] | We provide an explicit expression for the renormalized expectation value of the stress-energy tensor of a spin-$1/2$ field in a spatially flat FLRW universe. Its computation is based on the extension of the adiabatic regularization method to fermion fields introduced recently in the literature. The tensor is given in terms of UV-finite integrals in momentum space, which involve the mode functions that define the quantum state. As illustrative examples of the method efficiency, we see how to compute the renormalized energy density and pressure in two interesting cosmological scenarios: a de Sitter spacetime and a radiation-dominated universe. In the second case, we explicitly show that the late-time renormalized stress-energy tensor behaves as that of classical cold matter. We also check that, if we obtain the adiabatic expansion of the scalar field mode functions with a similar procedure to the one used for fermions, we recover the well-known WKB-type expansion. |
2210.10690 | De-Jun Wu | De-Jun Wu | Relativistic star solutions in Mass-varying Massive Gravity with a
diagonal metric | 14 pages; V2:References added, minor changes | Phys. Rev D 107, 044065(2023) | 10.1103/PhysRevD.107.044065 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate relativistic star solutions in Mass-Varying Massive Gravity
(MVMG) with a diagonal metric. Contrary to the intuition that there is no
fundamental difference between diagonal metric and non-diagonal metric
solutions regarding relativistic stars, we find that with a diagonal metric,
well-behaved relativistic star solutions may not exist except for trivial ones
in which the graviton mass is a constant, whereas non-trivial relativistic star
solutions had been found in MVMG with a non-diagonal metric. The reason is that
with a diagonal metric, the field equations constitute a system of
differential-algebraic equations of differential index-2 with two extra
constraints that have a significant influence on the system, rendering the
relativistic star solution with a non-trivial graviton mass configuration
impossible in most cases.
| [
{
"created": "Wed, 19 Oct 2022 16:05:39 GMT",
"version": "v1"
},
{
"created": "Wed, 19 Apr 2023 16:03:24 GMT",
"version": "v2"
}
] | 2023-04-20 | [
[
"Wu",
"De-Jun",
""
]
] | We investigate relativistic star solutions in Mass-Varying Massive Gravity (MVMG) with a diagonal metric. Contrary to the intuition that there is no fundamental difference between diagonal metric and non-diagonal metric solutions regarding relativistic stars, we find that with a diagonal metric, well-behaved relativistic star solutions may not exist except for trivial ones in which the graviton mass is a constant, whereas non-trivial relativistic star solutions had been found in MVMG with a non-diagonal metric. The reason is that with a diagonal metric, the field equations constitute a system of differential-algebraic equations of differential index-2 with two extra constraints that have a significant influence on the system, rendering the relativistic star solution with a non-trivial graviton mass configuration impossible in most cases. |
gr-qc/0406073 | Orhan Donmez | Orhan Donmez | Code Development of Three-Dimensional General Relativistic Hydrodynamics
with AMR(Adaptive-Mesh Refinement) and Results From Special and General
Relativistic Hydrodynamic | 18 pages, 13 figures. Accepted for publication in Astrophysics and
Space Science | Astrophys.Space Sci. 293 (2004) 323-354 | 10.1023/B:ASTR.0000044610.53714.95 | null | gr-qc | null | In this paper, the general procedure to solve the General Relativistic
Hydrodynamical(GRH) equations with Adaptive-Mesh Refinement (AMR) is presented.
In order to achieve, the GRH equations are written in the conservation form to
exploit their hyperbolic character. The numerical solutions of general
relativistic hydrodynamic equations are done by High Resolution Shock Capturing
schemes (HRSC), specifically designed to solve non-linear hyperbolic systems of
conservation laws. These schemes depend on the characteristic information of
the system. The Marquina fluxes with MUSCL left and right states are used to
solve GRH equations. First, different test problems with uniform and AMR grids
on the special relativistic hydrodynamics equations are carried out to verify
the second order convergence of the code in 1D, 2D and 3D. Results from uniform
and AMR grid are compared. It is found that adaptive grid does a better job
when the number of resolution is increased. Second, the general relativistic
hydrodynamical equations are tested using two different test problems which are
Geodesic flow and Circular motion of particle In order to this, the flux part
of GRH equations is coupled with source part using Strang splitting. The
coupling of the GRH equations is carried out in a treatment which gives second
order accurate solutions in space and time.
| [
{
"created": "Fri, 18 Jun 2004 16:29:00 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Donmez",
"Orhan",
""
]
] | In this paper, the general procedure to solve the General Relativistic Hydrodynamical(GRH) equations with Adaptive-Mesh Refinement (AMR) is presented. In order to achieve, the GRH equations are written in the conservation form to exploit their hyperbolic character. The numerical solutions of general relativistic hydrodynamic equations are done by High Resolution Shock Capturing schemes (HRSC), specifically designed to solve non-linear hyperbolic systems of conservation laws. These schemes depend on the characteristic information of the system. The Marquina fluxes with MUSCL left and right states are used to solve GRH equations. First, different test problems with uniform and AMR grids on the special relativistic hydrodynamics equations are carried out to verify the second order convergence of the code in 1D, 2D and 3D. Results from uniform and AMR grid are compared. It is found that adaptive grid does a better job when the number of resolution is increased. Second, the general relativistic hydrodynamical equations are tested using two different test problems which are Geodesic flow and Circular motion of particle In order to this, the flux part of GRH equations is coupled with source part using Strang splitting. The coupling of the GRH equations is carried out in a treatment which gives second order accurate solutions in space and time. |
1609.06296 | Shahen Hacyan | Shahen Hacyan | Gravitational radiation from a rotating magnetic dipole | new version | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The gravitational radiation emitted by a rotating magnetic dipole is
calculated. Formulas for the polarization amplitudes and the radiated power are
obtained in closed forms. A comparison is made with other sources of
gravitational and electromagnetic radiation, particularly neutron stars with
extremely powerful magnetic fields.
| [
{
"created": "Tue, 20 Sep 2016 19:24:51 GMT",
"version": "v1"
},
{
"created": "Fri, 13 Jan 2017 18:29:01 GMT",
"version": "v2"
}
] | 2017-01-16 | [
[
"Hacyan",
"Shahen",
""
]
] | The gravitational radiation emitted by a rotating magnetic dipole is calculated. Formulas for the polarization amplitudes and the radiated power are obtained in closed forms. A comparison is made with other sources of gravitational and electromagnetic radiation, particularly neutron stars with extremely powerful magnetic fields. |
2006.16522 | Avijit Chowdhury | Avijit Chowdhury and Narayan Banerjee | Echoes from a singularity | Version published in PRD | Phys. Rev. D 102, 124051 (2020) | 10.1103/PhysRevD.102.124051 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Though the cosmic censorship conjecture states that spacetime singularities
must be hidden from an asymptotic observer by an event horizon, naked
singularities can form as the end product of a gravitational collapse under
suitable initial conditions, so the question of how to observationally
distinguish such naked singularities from standard black hole spacetimes
becomes important. In the present paper, we try to address this question by
studying the ringdown profile of the Janis-Newman-Winicour (JNW) naked
singularity under axial gravitational perturbation. The JNW spacetime has a
surfacelike naked singularity that is sourced by a massless scalar field and
reduces to the Schwarzschild solution in absence of the scalar field. We show
that for low strength of the scalar field, the ringdown profile is dominated by
echoes which mellows down as the strength of the field increases to yield
characteristic quasinormal mode frequency of the JNW spacetime.
| [
{
"created": "Tue, 30 Jun 2020 04:35:58 GMT",
"version": "v1"
},
{
"created": "Tue, 1 Dec 2020 04:37:25 GMT",
"version": "v2"
},
{
"created": "Wed, 23 Dec 2020 14:10:22 GMT",
"version": "v3"
}
] | 2020-12-24 | [
[
"Chowdhury",
"Avijit",
""
],
[
"Banerjee",
"Narayan",
""
]
] | Though the cosmic censorship conjecture states that spacetime singularities must be hidden from an asymptotic observer by an event horizon, naked singularities can form as the end product of a gravitational collapse under suitable initial conditions, so the question of how to observationally distinguish such naked singularities from standard black hole spacetimes becomes important. In the present paper, we try to address this question by studying the ringdown profile of the Janis-Newman-Winicour (JNW) naked singularity under axial gravitational perturbation. The JNW spacetime has a surfacelike naked singularity that is sourced by a massless scalar field and reduces to the Schwarzschild solution in absence of the scalar field. We show that for low strength of the scalar field, the ringdown profile is dominated by echoes which mellows down as the strength of the field increases to yield characteristic quasinormal mode frequency of the JNW spacetime. |
2108.11666 | Alireza Talebian Ashkezari | Seyed Ali Hosseini Mansoori, Alireza Talebian, Zahra Molaee, and
Hassan Firouzjahi | Multi-field Mimetic Gravity | 23 pages, 11 figures, matches published version | Phys. Rev. D 105, 023529 (2022) | 10.1103/PhysRevD.105.023529 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we extend the mimetic gravity to the multi-field setup with a
curved field space manifold. The multi-field mimetic scenario is realized via
the singular limit of the conformal transformation between the auxiliary and
the physical metrics. We look for the cosmological implications of the setup
where it is shown that at the background level the mimetic energy density
mimics the roles of dark matter. At the perturbation level, the scalar field
perturbations are decomposed into the tangential and normal components with
respect to the background field space trajectory. The adiabatic perturbation
tangential to the background trajectory is frozen while the entropy mode
perpendicular to the background trajectory propagates with the speed of unity.
Whether or not the entropy perturbation is healthy directly depends on the
signature of the field-space metric. We perform the full non-linear Hamiltonian
analysis of the system with the curved field space manifold and calculate the
physical degrees of freedom verifying that the system is free from the
Ostrogradsky-type ghost.
| [
{
"created": "Thu, 26 Aug 2021 09:25:51 GMT",
"version": "v1"
},
{
"created": "Tue, 5 Oct 2021 05:08:20 GMT",
"version": "v2"
},
{
"created": "Fri, 28 Jan 2022 07:08:35 GMT",
"version": "v3"
}
] | 2022-01-31 | [
[
"Mansoori",
"Seyed Ali Hosseini",
""
],
[
"Talebian",
"Alireza",
""
],
[
"Molaee",
"Zahra",
""
],
[
"Firouzjahi",
"Hassan",
""
]
] | In this paper, we extend the mimetic gravity to the multi-field setup with a curved field space manifold. The multi-field mimetic scenario is realized via the singular limit of the conformal transformation between the auxiliary and the physical metrics. We look for the cosmological implications of the setup where it is shown that at the background level the mimetic energy density mimics the roles of dark matter. At the perturbation level, the scalar field perturbations are decomposed into the tangential and normal components with respect to the background field space trajectory. The adiabatic perturbation tangential to the background trajectory is frozen while the entropy mode perpendicular to the background trajectory propagates with the speed of unity. Whether or not the entropy perturbation is healthy directly depends on the signature of the field-space metric. We perform the full non-linear Hamiltonian analysis of the system with the curved field space manifold and calculate the physical degrees of freedom verifying that the system is free from the Ostrogradsky-type ghost. |
0811.4667 | Valerio Faraoni | Valerio Faraoni, Changjun Gao, Xuelei Chen, and You-Gen Shen | What is the fate of a black hole embedded in an expanding universe? | 9 pages, LaTex, to appear in Phys. Lett. B | Phys.Lett.B671:7-9,2009 | 10.1016/j.physletb.2008.11.067 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Within a large class of exact solutions of the Einstein equations describing
a black hole embedded in a Friedmann universe it is shown that, under certain
assumptions, only those with comoving Hawking-Hayward quasi-local mass are
generic, in the sense that they are late-time attractors.
| [
{
"created": "Fri, 28 Nov 2008 08:32:06 GMT",
"version": "v1"
}
] | 2009-03-04 | [
[
"Faraoni",
"Valerio",
""
],
[
"Gao",
"Changjun",
""
],
[
"Chen",
"Xuelei",
""
],
[
"Shen",
"You-Gen",
""
]
] | Within a large class of exact solutions of the Einstein equations describing a black hole embedded in a Friedmann universe it is shown that, under certain assumptions, only those with comoving Hawking-Hayward quasi-local mass are generic, in the sense that they are late-time attractors. |
gr-qc/0305099 | Jean-Philippe Uzan | George F.R. Ellis, Jean-Philippe Uzan | `c' is the speed of light, isn't it? | 14 pages, Latex | Am.J.Phys. 73 (2005) 240-247 | 10.1119/1.1819929 | null | gr-qc astro-ph hep-th | null | Theories proposing a varying speed of light have recently been widely
promoted under the claim that they offer an alternative way of solving the
standard cosmological problems. Recent observational hints that the fine
structure constant may have varied during over cosmological scales also has
given impetus to these models. In theoretical physics the speed of light, $c$,
is hidden in almost all equations but with different facets that we try to
distinguish. Together with a reminder on scalar-tensor theories of gravity,
this sheds some light on these proposed varying speed of light theories.
| [
{
"created": "Tue, 27 May 2003 16:54:07 GMT",
"version": "v1"
},
{
"created": "Thu, 12 Jun 2003 09:47:05 GMT",
"version": "v2"
}
] | 2015-06-25 | [
[
"Ellis",
"George F. R.",
""
],
[
"Uzan",
"Jean-Philippe",
""
]
] | Theories proposing a varying speed of light have recently been widely promoted under the claim that they offer an alternative way of solving the standard cosmological problems. Recent observational hints that the fine structure constant may have varied during over cosmological scales also has given impetus to these models. In theoretical physics the speed of light, $c$, is hidden in almost all equations but with different facets that we try to distinguish. Together with a reminder on scalar-tensor theories of gravity, this sheds some light on these proposed varying speed of light theories. |
2201.09026 | Shao-Wen Wei | Ming-Da Li, Hui-Min Wang, Shao-Wen Wei | Triple points and novel phase transitions of dyonic AdS black holes with
quasitopological electromagnetism | 18 pages, 11 figures and 2 tables. Major revision | Phys. Rev. D 105, 104048 (2022) | 10.1103/PhysRevD.105.104048 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Quasitopological electromagnetism has an important influence on the strong
gravity of dyonic black hole. For example three photon spheres with one being
stable are found and we wish to test them with the observed black hole shadow.
We are primarily concerned with the thermodynamics and phase transition for a
dyonic anti-de Sitter (AdS) black hole when the quasitopological
electromagnetism is included.Unlike in a black hole solution without
quasitopological electromagnetism, we observe a triple point phase structure by
varying the coupling parameters. Of particular interest, for certain parameter
values, two separate coexistence curves are present, which is an additional
novel phase structure that is absent in a black hole solution without
quasitopological electromagnetism. The critical exponents share the same values
as mean field theory. These results uncover the intriguing properties of dyonic
AdS black holes with quasitopological electromagnetism from a thermodynamic
point of view.
| [
{
"created": "Sat, 22 Jan 2022 11:48:10 GMT",
"version": "v1"
},
{
"created": "Thu, 26 May 2022 06:23:00 GMT",
"version": "v2"
}
] | 2022-06-02 | [
[
"Li",
"Ming-Da",
""
],
[
"Wang",
"Hui-Min",
""
],
[
"Wei",
"Shao-Wen",
""
]
] | Quasitopological electromagnetism has an important influence on the strong gravity of dyonic black hole. For example three photon spheres with one being stable are found and we wish to test them with the observed black hole shadow. We are primarily concerned with the thermodynamics and phase transition for a dyonic anti-de Sitter (AdS) black hole when the quasitopological electromagnetism is included.Unlike in a black hole solution without quasitopological electromagnetism, we observe a triple point phase structure by varying the coupling parameters. Of particular interest, for certain parameter values, two separate coexistence curves are present, which is an additional novel phase structure that is absent in a black hole solution without quasitopological electromagnetism. The critical exponents share the same values as mean field theory. These results uncover the intriguing properties of dyonic AdS black holes with quasitopological electromagnetism from a thermodynamic point of view. |
2203.06016 | Valeriya Korol | Pau Amaro Seoane, Jeff Andrews, Manuel Arca Sedda, Abbas Askar,
Quentin Baghi, Razvan Balasov, Imre Bartos, Simone S. Bavera, Jillian
Bellovary, Christopher P. L. Berry, Emanuele Berti, Stefano Bianchi, Laura
Blecha, Ste\'phane Blondin, Tamara Bogdanovi\'c, Samuel Boissier, Matteo
Bonetti, Silvia Bonoli, Elisa Bortolas, Katelyn Breivik, Pedro R. Capelo,
Laurentiu Caramete, Federico Cattorini, Maria Charisi, Sylvain Chaty, Xian
Chen, Martyna Chru\'sli\'nska, Alvin J. K. Chua, Ross Church, Monica Colpi,
Daniel D'Orazio, Camilla Danielski, Melvyn B. Davies, Pratika Dayal,
Alessandra De Rosa, Andrea Derdzinski, Kyriakos Destounis, Massimo Dotti,
Ioana Du\c{t}an, Irina Dvorkin, Gaia Fabj, Thierry Foglizzo, Saavik Ford,
Jean-Baptiste Fouvry, Alessia Franchini, Tassos Fragos, Chris Fryer, Massimo
Gaspari, Davide Gerosa, Luca Graziani, Paul Groot, Melanie Habouzit, Daryl
Haggard, Zoltan Haiman, Wen-Biao Han, Alina Istrate, Peter H. Johansson,
Fazeel Mahmood Khan, Tomas Kimpson, Kostas Kokkotas, Albert Kong, Valeriya
Korol, Kyle Kremer, Thomas Kupfer, Astrid Lamberts, Shane Larson, Mike Lau,
Dongliang Liu, Nicole Lloyd-Ronning, Giuseppe Lodato, Alessandro Lupi,
Chung-Pei Ma, Tomas Maccarone, Ilya Mandel, Alberto Mangiagli, Michela
Mapelli, Ste\'ephane Mathis, Lucio Mayer, Sean McGee, Berry McKernan, M.
Coleman Miller, David F. Mota, Matthew Mumpower, Syeda S Nasim, Gijs
Nelemans, Scott Noble, Fabio Pacucci, Francesca Panessa, Vasileio
Paschalidis, Hugo Pfister, Delphine Porquet, John Quenby, Angelo Ricarte,
Friedrich K. R\"opke, John Regan, Stephan Rosswog, Ashley Ruiter, Milton
Ruiz, Jessie Runnoe, Raffaella Schneider, Jeremy Schnittman, Amy Secunda,
Alberto Sesana, Naoki Seto, Lijing Shao, Stuart Shapiro, Carlos Sopuerta,
Nicholas C. Stone, Arthur Suvorov, Nicola Tamanini, Tomas Tamfal, Thomas
Tauris, Karel Temmink, John Tomsick, Silvia Toonen, Alejandro Torres-Orjuela,
Martina Toscani, Antonios Tsokaros, Caner Unal, Ver\'onica V\'azquez-Aceves,
Rosa Valiante, Maurice van Putten, Jan van Roestel, Christian Vignali, Marta
Volonteri, Kinwah Wu, Ziri Younsi, Shenghua Yu, Silvia Zane, Lorenz Zwick,
Fabio Antonini, Vishal Baibhav, Enrico Barausse, Alexander Bonilla Rivera,
Marica Branchesi, Graziella Branduardi-Raymont, Kevin Burdge, Srija
Chakraborty, Jorge Cuadra, Kristen Dage, Benjamin Davis, Selma E. de Mink,
Roberto Decarli, Daniela Doneva, Stephanie Escoffier, Giacomo Fragione,
Poshak Gandhi, Francesco Haardt, Carlos O. Lousto, Samaya Nissanke, Jason
Nordhaus, Richard O'Shaughnessy, Simon Portegies Zwart, Adam Pound, Fabian
Schussler, Olga Sergijenko, Alessandro Spallicci, Daniele Vernieri, Alejandro
Vigna-G\'omez | Astrophysics with the Laser Interferometer Space Antenna | null | Living Reviews in Relativity, Volume 26, Article number: 2 (2023) | 10.1007/s41114-022-00041-y | null | gr-qc astro-ph.CO astro-ph.GA astro-ph.HE astro-ph.IM astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Laser Interferometer Space Antenna (LISA) will be a transformative
experiment for gravitational wave astronomy, and, as such, it will offer unique
opportunities to address many key astrophysical questions in a completely novel
way. The synergy with ground-based and space-born instruments in the
electromagnetic domain, by enabling multi-messenger observations, will add
further to the discovery potential of LISA. The next decade is crucial to
prepare the astrophysical community for LISA's first observations. This review
outlines the extensive landscape of astrophysical theory, numerical
simulations, and astronomical observations that are instrumental for modeling
and interpreting the upcoming LISA datastream. To this aim, the current
knowledge in three main source classes for LISA is reviewed; ultracompact
stellar-mass binaries, massive black hole binaries, and extreme or intermediate
mass ratio inspirals. The relevant astrophysical processes and the established
modeling techniques are summarized. Likewise, open issues and gaps in our
understanding of these sources are highlighted, along with an indication of how
LISA could help making progress in the different areas. New research avenues
that LISA itself, or its joint exploitation with upcoming studies in the
electromagnetic domain, will enable, are also illustrated. Improvements in
modeling and analysis approaches, such as the combination of numerical
simulations and modern data science techniques, are discussed. This review is
intended to be a starting point for using LISA as a new discovery tool for
understanding our Universe.
| [
{
"created": "Fri, 11 Mar 2022 15:38:06 GMT",
"version": "v1"
},
{
"created": "Thu, 25 May 2023 11:14:45 GMT",
"version": "v2"
}
] | 2023-05-26 | [
[
"Seoane",
"Pau Amaro",
""
],
[
"Andrews",
"Jeff",
""
],
[
"Sedda",
"Manuel Arca",
""
],
[
"Askar",
"Abbas",
""
],
[
"Baghi",
"Quentin",
""
],
[
"Balasov",
"Razvan",
""
],
[
"Bartos",
"Imre",
""
],
[
... | The Laser Interferometer Space Antenna (LISA) will be a transformative experiment for gravitational wave astronomy, and, as such, it will offer unique opportunities to address many key astrophysical questions in a completely novel way. The synergy with ground-based and space-born instruments in the electromagnetic domain, by enabling multi-messenger observations, will add further to the discovery potential of LISA. The next decade is crucial to prepare the astrophysical community for LISA's first observations. This review outlines the extensive landscape of astrophysical theory, numerical simulations, and astronomical observations that are instrumental for modeling and interpreting the upcoming LISA datastream. To this aim, the current knowledge in three main source classes for LISA is reviewed; ultracompact stellar-mass binaries, massive black hole binaries, and extreme or intermediate mass ratio inspirals. The relevant astrophysical processes and the established modeling techniques are summarized. Likewise, open issues and gaps in our understanding of these sources are highlighted, along with an indication of how LISA could help making progress in the different areas. New research avenues that LISA itself, or its joint exploitation with upcoming studies in the electromagnetic domain, will enable, are also illustrated. Improvements in modeling and analysis approaches, such as the combination of numerical simulations and modern data science techniques, are discussed. This review is intended to be a starting point for using LISA as a new discovery tool for understanding our Universe. |
gr-qc/9801019 | I. Kouletsis | I. Kouletsis | A classical history theory: Geometrodynamics and general field dynamics
regained | 23 pages, no figures, LaTeX | null | null | Imperial/TP/97-98/17 | gr-qc | null | Assuming that the Hamiltonian of a canonical field theory can be written in
the form N H + N^i H_i, and using as the only input the actual choice of the
canonical variables, we derive: (i) The algebra satisfied by H and H_i, (ii)
any constraints, and (iii) the most general canonical representation for H and
H_i. This completes previous work by Hojman, Kuchar and Teitelboim who had to
impose a set of additional postulates, among which were the form of the
canonical algebra and the requirement of path-independence of the dynamical
evolution. A prominent feature of the present approach is the replacement of
the equal-time Poisson bracket with one evaluated at general times. The
resulting formalism is therefore an example of a classical history theory -- an
interesting fact, especially in view of recent work by Isham et al.
| [
{
"created": "Thu, 8 Jan 1998 14:33:33 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Kouletsis",
"I.",
""
]
] | Assuming that the Hamiltonian of a canonical field theory can be written in the form N H + N^i H_i, and using as the only input the actual choice of the canonical variables, we derive: (i) The algebra satisfied by H and H_i, (ii) any constraints, and (iii) the most general canonical representation for H and H_i. This completes previous work by Hojman, Kuchar and Teitelboim who had to impose a set of additional postulates, among which were the form of the canonical algebra and the requirement of path-independence of the dynamical evolution. A prominent feature of the present approach is the replacement of the equal-time Poisson bracket with one evaluated at general times. The resulting formalism is therefore an example of a classical history theory -- an interesting fact, especially in view of recent work by Isham et al. |
1312.1144 | Chen Songbai | Hao Liao, Songbai Chen, Jiliang Jing | Absorption cross section and Hawking radiation of the electromagnetic
field with Weyl corrections | 10 pages, 8 figures. Accepted for publication in Physics Letters B | Phys. Lett. B 728 (2014) 457-461 | 10.1016/j.physletb.2013.12.018 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We have investigated the absorption cross section and the Hawking radiation
of electromagnetic field with Weyl correction in the background of a
four-dimensional Schwarzschild black hole spacetime. Our results show that the
properties of the absorption cross section and the Hawking radiation depend not
only on the Weyl correction parameter, but also on the parity of the
electromagnetic field, which is quite different from those of the usual
electromagnetic field without Weyl correction in the four-dimensional
spacetime. With increase of Weyl correction parameter, the absorption
probability, the absorption cross section, the power emission spectra and the
luminosity of Hawking radiation decreases with Weyl correction parameter for
the odd-parity electromagnetic field and increases with the event-parity
electromagnetic field.
| [
{
"created": "Wed, 4 Dec 2013 13:05:18 GMT",
"version": "v1"
},
{
"created": "Thu, 19 Dec 2013 00:53:15 GMT",
"version": "v2"
}
] | 2015-06-18 | [
[
"Liao",
"Hao",
""
],
[
"Chen",
"Songbai",
""
],
[
"Jing",
"Jiliang",
""
]
] | We have investigated the absorption cross section and the Hawking radiation of electromagnetic field with Weyl correction in the background of a four-dimensional Schwarzschild black hole spacetime. Our results show that the properties of the absorption cross section and the Hawking radiation depend not only on the Weyl correction parameter, but also on the parity of the electromagnetic field, which is quite different from those of the usual electromagnetic field without Weyl correction in the four-dimensional spacetime. With increase of Weyl correction parameter, the absorption probability, the absorption cross section, the power emission spectra and the luminosity of Hawking radiation decreases with Weyl correction parameter for the odd-parity electromagnetic field and increases with the event-parity electromagnetic field. |
gr-qc/0406015 | Yuri Obukhov | Yu.N. Obukhov, J.G. Pereira | Lessons of spin and torsion: Reply to ``Consistent coupling to Dirac
fields in teleparallelism" | Revtex, 4 pages, no figures | Phys.Rev. D69 (2004) 128502 | 10.1103/PhysRevD.69.128502 | null | gr-qc | null | In reply to the criticism made by Mielke in the pereceding Comment [Phys.
Rev. D69 (2004) 128501] on our recent paper, we once again explicitly
demonstrate the inconsistency of the coupling of a Dirac field to gravitation
in the teleparallel equivalent of general relativity. Moreover, we stress that
the mentioned inconsistency is generic for {\it all} sources with spin and is
by no means restricted to the Dirac field. In this sense the
$SL(4,R)$-covariant generalization of the spinor fields in the teleparallel
gravity theory is irrelevant to the inconsistency problem.
| [
{
"created": "Fri, 4 Jun 2004 13:26:37 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Obukhov",
"Yu. N.",
""
],
[
"Pereira",
"J. G.",
""
]
] | In reply to the criticism made by Mielke in the pereceding Comment [Phys. Rev. D69 (2004) 128501] on our recent paper, we once again explicitly demonstrate the inconsistency of the coupling of a Dirac field to gravitation in the teleparallel equivalent of general relativity. Moreover, we stress that the mentioned inconsistency is generic for {\it all} sources with spin and is by no means restricted to the Dirac field. In this sense the $SL(4,R)$-covariant generalization of the spinor fields in the teleparallel gravity theory is irrelevant to the inconsistency problem. |
2012.00847 | Ivan Stefanov | Ivan Zhivkov Stefanov | Mass-spin relation of black holes obtained by twin high-frequency
quasi-periodic oscillations | null | IJMPD, 29, No. 16, 2050110 (2020) | 10.1142/S0218271820501102 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The paper studies the uniqueness and the monotonicity of the mass-spin
relation of black holes the X-ray power density spectra of which contain twin
high-frequency quasi-periodic oscillations in 3:2 ratio. It is found that for
geodesic models the properties of the mass-spin relation are independent of the
observed frequencies, i.e. they are independent of the particular object. Some
results are valid for all geodesic models. For concreteness two of the most
commonly used models are studied here: the 3 : 1 nonlinear epicyclic resonance
model and its Keplerian version.
| [
{
"created": "Tue, 1 Dec 2020 21:34:45 GMT",
"version": "v1"
}
] | 2023-05-03 | [
[
"Stefanov",
"Ivan Zhivkov",
""
]
] | The paper studies the uniqueness and the monotonicity of the mass-spin relation of black holes the X-ray power density spectra of which contain twin high-frequency quasi-periodic oscillations in 3:2 ratio. It is found that for geodesic models the properties of the mass-spin relation are independent of the observed frequencies, i.e. they are independent of the particular object. Some results are valid for all geodesic models. For concreteness two of the most commonly used models are studied here: the 3 : 1 nonlinear epicyclic resonance model and its Keplerian version. |
1904.08521 | Volker Perlick | Wolfgang Hasse and Volker Perlick | Redshift in Finsler spacetimes | 12 pages, 3 figures; minor changes, five references added | Phys. Rev. D 100, 024033 (2019) | 10.1103/PhysRevD.100.024033 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive and discuss a general redshift formula in Finsler spacetimes. The
condition for the existence of a redshift potential is worked out. The results
are illustrated with two examples, one refering to a spherically symmetric and
static Finsler spacetime and the other to a cosmological Finsler spacetime.
| [
{
"created": "Wed, 17 Apr 2019 22:20:49 GMT",
"version": "v1"
},
{
"created": "Tue, 25 Jun 2019 22:09:10 GMT",
"version": "v2"
}
] | 2019-07-18 | [
[
"Hasse",
"Wolfgang",
""
],
[
"Perlick",
"Volker",
""
]
] | We derive and discuss a general redshift formula in Finsler spacetimes. The condition for the existence of a redshift potential is worked out. The results are illustrated with two examples, one refering to a spherically symmetric and static Finsler spacetime and the other to a cosmological Finsler spacetime. |
1712.02464 | Kian Ming | Kian Ming, Triyanta, J. S. Kosasih | Gravitoelectromagnetism in Teleparallel Equivalent of General
Relativity: A New Alternative | null | Kian Ming, Triyanta, dan Kosasih, J. S., (2017):
Gravitoelectromagnetism in Teleparallel Equivalent of General Relativity: A
New Alternative, International Journal of Modern Physics D, 26, 1750092 | 10.1142/S0218271817500924 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Spaniol and Andrade introduced grvitoelectromagnetism in TEGR by considering
superpotentials, times the determinant of tetrads, as the
gravitoelectromagnetic fields. However, since this defined
gravitoelectromagnetic field strength does not give rise to a complete set of
Maxwell-like equations, we propose an alternative definition of the
gravitoelectromagnetic field strength: instead of superpotentials, torsions are
taken as the gravitoelectromagnetic field strengths. Based on this new proposal
we are able to derive a complete set of Maxwell-like equations. We then apply
them to obtain explicit expressions of the gravitoelectromagnetic fields both
in Schwarzchilds spacetime and for gravitational waves.
| [
{
"created": "Thu, 7 Dec 2017 01:11:12 GMT",
"version": "v1"
}
] | 2017-12-13 | [
[
"Ming",
"Kian",
""
],
[
"Triyanta",
"",
""
],
[
"Kosasih",
"J. S.",
""
]
] | Spaniol and Andrade introduced grvitoelectromagnetism in TEGR by considering superpotentials, times the determinant of tetrads, as the gravitoelectromagnetic fields. However, since this defined gravitoelectromagnetic field strength does not give rise to a complete set of Maxwell-like equations, we propose an alternative definition of the gravitoelectromagnetic field strength: instead of superpotentials, torsions are taken as the gravitoelectromagnetic field strengths. Based on this new proposal we are able to derive a complete set of Maxwell-like equations. We then apply them to obtain explicit expressions of the gravitoelectromagnetic fields both in Schwarzchilds spacetime and for gravitational waves. |
gr-qc/0410025 | Bin Wang | Cheng-Gang Shao, Bin Wang, Elcio Abdalla and Ru-Keng Su | Quasinormal modes in time-dependent black hole background | revised version, 20 pages, accepted for publication in Phys. Rev. D | Phys.Rev. D71 (2005) 044003 | 10.1103/PhysRevD.71.044003 | null | gr-qc astro-ph hep-th | null | We have studied the evolution of the massless scalar field propagating in
time-dependent charged Vaidya black hole background. A generalized tortoise
coordinate transformation were used to study the evolution of the massless
scalar field. It is shown that, for the slowest damped quasinormal modes, the
approximate formulae in stationary Reissner-Nordstr\"{o}m black hole turn out
to be a reasonable prescription, showing that results from quasinormal mode
analysis are rather robust.
| [
{
"created": "Wed, 6 Oct 2004 08:00:07 GMT",
"version": "v1"
},
{
"created": "Tue, 25 Jan 2005 14:55:40 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Shao",
"Cheng-Gang",
""
],
[
"Wang",
"Bin",
""
],
[
"Abdalla",
"Elcio",
""
],
[
"Su",
"Ru-Keng",
""
]
] | We have studied the evolution of the massless scalar field propagating in time-dependent charged Vaidya black hole background. A generalized tortoise coordinate transformation were used to study the evolution of the massless scalar field. It is shown that, for the slowest damped quasinormal modes, the approximate formulae in stationary Reissner-Nordstr\"{o}m black hole turn out to be a reasonable prescription, showing that results from quasinormal mode analysis are rather robust. |
1204.0789 | Tapas Kumar Das | Shilpi Agarwal, Tapas K. Das, Rukmini Dey and Sankhasubhra Nag | An Analytical Study on the Multi-critical Behaviour and Related
Bifurcation Phenomena for Relativistic Black Hole Accretion | 19 pages, 2 eps figures, to appear in "General Relativity and
Gravitation" | null | 10.1007/s10714-012-1358-z | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We apply the theory of algebraic polynomials to analytically study the
transonic properties of general relativistic hydrodynamic axisymmetric
accretion onto non-rotating astrophysical black holes. For such accretion
phenomena, the conserved specific energy of the flow, which turns out to be one
of the two first integrals of motion in the system studied, can be expressed as
a 8$^{th}$ degree polynomial of the critical point of the flow configuration.
We then construct the corresponding Sturm's chain algorithm to calculate the
number of real roots lying within the astrophysically relevant domain of
$\mathbb{R}$. This allows, for the first time in literature, to {\it
analytically} find out the maximum number of physically acceptable solution an
accretion flow with certain geometric configuration, space-time metric, and
equation of state can have, and thus to investigate its multi-critical
properties {\it completely analytically}, for accretion flow in which the
location of the critical points can not be computed without taking recourse to
the numerical scheme. This work can further be generalized to analytically
calculate the maximal number of equilibrium points certain autonomous dynamical
system can have in general. We also demonstrate how the transition from a
mono-critical to multi-critical (or vice versa) flow configuration can be
realized through the saddle-centre bifurcation phenomena using certain
techniques of the catastrophe theory.
| [
{
"created": "Tue, 3 Apr 2012 20:00:04 GMT",
"version": "v1"
}
] | 2012-04-05 | [
[
"Agarwal",
"Shilpi",
""
],
[
"Das",
"Tapas K.",
""
],
[
"Dey",
"Rukmini",
""
],
[
"Nag",
"Sankhasubhra",
""
]
] | We apply the theory of algebraic polynomials to analytically study the transonic properties of general relativistic hydrodynamic axisymmetric accretion onto non-rotating astrophysical black holes. For such accretion phenomena, the conserved specific energy of the flow, which turns out to be one of the two first integrals of motion in the system studied, can be expressed as a 8$^{th}$ degree polynomial of the critical point of the flow configuration. We then construct the corresponding Sturm's chain algorithm to calculate the number of real roots lying within the astrophysically relevant domain of $\mathbb{R}$. This allows, for the first time in literature, to {\it analytically} find out the maximum number of physically acceptable solution an accretion flow with certain geometric configuration, space-time metric, and equation of state can have, and thus to investigate its multi-critical properties {\it completely analytically}, for accretion flow in which the location of the critical points can not be computed without taking recourse to the numerical scheme. This work can further be generalized to analytically calculate the maximal number of equilibrium points certain autonomous dynamical system can have in general. We also demonstrate how the transition from a mono-critical to multi-critical (or vice versa) flow configuration can be realized through the saddle-centre bifurcation phenomena using certain techniques of the catastrophe theory. |
1510.01353 | Irina Dymnikova | Irina Dymnikova and Evgeny Galaktionov | Regular rotating electrically charged black holes and solitons in
nonlinear electrodynamics minimally coupled to gravity | 17 pages, 3 figures. arXiv admin note: substantial text overlap with
arXiv:1510.01126 | Class. Quant. Grav. 32 (2015) 165015 | 10.1088/0264-9381/32/16/165015 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In nonlinear electrodynamics coupled to gravity, regular spherically
symmetric electrically charged solutions satisfy the weak energy condition and
have obligatory de Sitter centre. By the G\"urses-G\"ursey algorithm they are
transformed to spinning electrically charged solutions asymptotically
Kerr-Newman for a distant observer. Rotation transforms de Sitter center into
de Sitter vacuum surface which contains equatorial disk $r=0$ as a bridge. We
present general analysis of the horizons, ergoregions and de Sitter surfaces,
as well as the conditions of the existence of regular solutions to the field
equations. We find asymptotic solutions and show that de Sitter vacuum surfaces
have properties of a perfect conductor and ideal diamagnetic, violation of the
weak energy condition is prevented by the basic requirement of electrodynamics
of continued media, and the Kerr ring singularity is replaced with the
superconducting current.
| [
{
"created": "Fri, 2 Oct 2015 14:07:15 GMT",
"version": "v1"
}
] | 2015-10-07 | [
[
"Dymnikova",
"Irina",
""
],
[
"Galaktionov",
"Evgeny",
""
]
] | In nonlinear electrodynamics coupled to gravity, regular spherically symmetric electrically charged solutions satisfy the weak energy condition and have obligatory de Sitter centre. By the G\"urses-G\"ursey algorithm they are transformed to spinning electrically charged solutions asymptotically Kerr-Newman for a distant observer. Rotation transforms de Sitter center into de Sitter vacuum surface which contains equatorial disk $r=0$ as a bridge. We present general analysis of the horizons, ergoregions and de Sitter surfaces, as well as the conditions of the existence of regular solutions to the field equations. We find asymptotic solutions and show that de Sitter vacuum surfaces have properties of a perfect conductor and ideal diamagnetic, violation of the weak energy condition is prevented by the basic requirement of electrodynamics of continued media, and the Kerr ring singularity is replaced with the superconducting current. |
2007.08166 | \.Ibrahim Semiz | \.Ibrahim Semiz | The general static spherical perfect fluid solution with EoS parameter
w=-1/5 | Added tables and conformal diagrams. Close to published version,
which contains improved versions of some Penrose diagrams and an appendix on
the Buchdahl transformation | Class. Quantum Grav. 39 215002 (2022) | 10.1088/1361-6382/ac8cca | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The general analytical solution for the static spherically symmetric metric
supported by a perfect fluid with isothermal (proportional) equation-of-state
$p = w \rho$ is not known at the time of this writing, except for the trivial
cases $w=0$ and $w=-1$; and for $w=-1/3$. We show that if Buchdahl coordinates
are used, the problem becomes analytically solvable for $w=-1/5$; display and
discuss the solution(s), and exhibit the connection of this case to the $w=-1$
case.
| [
{
"created": "Thu, 16 Jul 2020 07:59:45 GMT",
"version": "v1"
},
{
"created": "Sat, 5 Sep 2020 00:24:01 GMT",
"version": "v2"
},
{
"created": "Wed, 6 Apr 2022 18:26:44 GMT",
"version": "v3"
},
{
"created": "Sat, 29 Oct 2022 14:25:29 GMT",
"version": "v4"
}
] | 2022-11-01 | [
[
"Semiz",
"İbrahim",
""
]
] | The general analytical solution for the static spherically symmetric metric supported by a perfect fluid with isothermal (proportional) equation-of-state $p = w \rho$ is not known at the time of this writing, except for the trivial cases $w=0$ and $w=-1$; and for $w=-1/3$. We show that if Buchdahl coordinates are used, the problem becomes analytically solvable for $w=-1/5$; display and discuss the solution(s), and exhibit the connection of this case to the $w=-1$ case. |
1203.2154 | Jeffrey Winicour | Jeffrey Winicour | Boundary Conditions for the Gravitational Field | Some clarification added and typos corrected. Final version to appear
in Classical and Quantum Gravity | Class. Quantum Grav. 29 (2012) 113001 | 10.1088/0264-9381/29/11/113001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A review of the treatment of boundaries in general relativity is presented
with the emphasis on application to the formulations of Einstein's equations
used in numerical relativity. At present, it is known how to treat boundaries
in the harmonic formulation of Einstein's equations and a tetrad formulation of
the Einstein-Bianchi system. However, a universal approach valid for other
formulations is not in hand. In particular, there is no satisfactory boundary
theory for the 3+1 formulations which have been highly successful in binary
black hole simulation. I discuss the underlying problems that make the
initial-boundary value problem much more complicated than the Cauchy problem. I
review the progress that has been made and the important open questions that
remain.
| [
{
"created": "Fri, 9 Mar 2012 18:01:20 GMT",
"version": "v1"
},
{
"created": "Tue, 24 Apr 2012 15:52:44 GMT",
"version": "v2"
}
] | 2015-06-04 | [
[
"Winicour",
"Jeffrey",
""
]
] | A review of the treatment of boundaries in general relativity is presented with the emphasis on application to the formulations of Einstein's equations used in numerical relativity. At present, it is known how to treat boundaries in the harmonic formulation of Einstein's equations and a tetrad formulation of the Einstein-Bianchi system. However, a universal approach valid for other formulations is not in hand. In particular, there is no satisfactory boundary theory for the 3+1 formulations which have been highly successful in binary black hole simulation. I discuss the underlying problems that make the initial-boundary value problem much more complicated than the Cauchy problem. I review the progress that has been made and the important open questions that remain. |
1806.11160 | Juan Calderon Bustillo | Juan Calder\'on Bustillo, James A. Clark, Pablo Laguna and Deirdre
Shoemaker | Tracking black hole kicks from gravitational wave observations | 6 pages, 5 figures | Phys. Rev. Lett. 121, 191102 (2018) | 10.1103/PhysRevLett.121.191102 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Coalescing binary black holes emit anisotropic gravitational radiation. This
causes a net emission of linear momentum that produces a gradual acceleration
of the source. As a result, the final remnant black hole acquires a
characteristic velocity known as recoil velocity or gravitational kick. The
symmetries of gravitational wave emission are reflected in the interactions of
the gravitational wave modes emitted by the binary. In this work we make use of
the rich information encoded in the higher-order modes of the gravitational
wave emission to infer the component of the kick along the line-of-sight (or
\textit{radial kick}). We do this by performing parameter inference on
simulated signals given by numerical relativity waveforms for non-spinning
binaries using numerical relativity templates of aligned-spin (non-precessing)
binary black holes. We find that for suitable sources, namely those with mass
ratio $q\geq 2$ and total mass $M \sim 100M_\odot$, and for modest radial kicks
of $120km/s$, the $90\%$ credible intervals of our posterior probability
distributions can exclude a zero kick at a signal-to-noise ratio of $15$; using
a single Advanced LIGO detector working at its early sensitivity. The
measurement of a non-zero radial kick component would provide the first
observational signature of net transport of linear momentum by gravitational
waves away from their source.
| [
{
"created": "Thu, 28 Jun 2018 19:52:19 GMT",
"version": "v1"
},
{
"created": "Fri, 12 Oct 2018 13:57:05 GMT",
"version": "v2"
}
] | 2018-11-14 | [
[
"Bustillo",
"Juan Calderón",
""
],
[
"Clark",
"James A.",
""
],
[
"Laguna",
"Pablo",
""
],
[
"Shoemaker",
"Deirdre",
""
]
] | Coalescing binary black holes emit anisotropic gravitational radiation. This causes a net emission of linear momentum that produces a gradual acceleration of the source. As a result, the final remnant black hole acquires a characteristic velocity known as recoil velocity or gravitational kick. The symmetries of gravitational wave emission are reflected in the interactions of the gravitational wave modes emitted by the binary. In this work we make use of the rich information encoded in the higher-order modes of the gravitational wave emission to infer the component of the kick along the line-of-sight (or \textit{radial kick}). We do this by performing parameter inference on simulated signals given by numerical relativity waveforms for non-spinning binaries using numerical relativity templates of aligned-spin (non-precessing) binary black holes. We find that for suitable sources, namely those with mass ratio $q\geq 2$ and total mass $M \sim 100M_\odot$, and for modest radial kicks of $120km/s$, the $90\%$ credible intervals of our posterior probability distributions can exclude a zero kick at a signal-to-noise ratio of $15$; using a single Advanced LIGO detector working at its early sensitivity. The measurement of a non-zero radial kick component would provide the first observational signature of net transport of linear momentum by gravitational waves away from their source. |
2007.10223 | Andr\'es Ace\~na | Andr\'es Ace\~na | CMC surfaces and area-charge inequality for a spheroidal ECD spacetime | 19 pages, 12 figures | Phys. Rev. D 102, 104046 (2020) | 10.1103/PhysRevD.102.104046 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the spacetime presented by Bonnor \cite{Bonnor98}, whose matter
content is a spheroid of electrically counterpoised dust, in the context of the
geometrical inequalities between area and charge. We determine numerically the
constant mean curvature surfaces that are candidates to be stable isoperimetric
surfaces and analyze the relation between area and charge for them, showing
that a previously proved inequality is far from being saturated. We also show
that the maximal initial data has a cylindrical limit where the minimum of the
area-charge relation is attained.
| [
{
"created": "Mon, 20 Jul 2020 16:09:17 GMT",
"version": "v1"
}
] | 2020-11-25 | [
[
"Aceña",
"Andrés",
""
]
] | We consider the spacetime presented by Bonnor \cite{Bonnor98}, whose matter content is a spheroid of electrically counterpoised dust, in the context of the geometrical inequalities between area and charge. We determine numerically the constant mean curvature surfaces that are candidates to be stable isoperimetric surfaces and analyze the relation between area and charge for them, showing that a previously proved inequality is far from being saturated. We also show that the maximal initial data has a cylindrical limit where the minimum of the area-charge relation is attained. |
1810.03816 | Jibitesh Dutta | Hmar Zonunmawia, Wompherdeiki Khyllep, Jibitesh Dutta and Laur J\"arv | Cosmological dynamics of brane gravity: A global dynamical system
perspective | 25 pages and 8 figures. Accepted in PRD | Physical Review D, 98, 2018 | 10.1103/PhysRevD.98.083532 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The braneworld model of gravity is well-known for several notable
cosmological features such as self-acceleration originating from a geometric
and not matter source, effective dark energy behavior with phantom
characteristics but not leading to a Big-Rip singularity, rough resemblance to
the $\Lambda$CDM evolution, etc. The dynamical system tools usually allow us to
obtain generic conclusions on the global dynamics of a system over a wide range
of initial conditions. With this motivation, in order to recover the important
features of the braneworld model from a more global perspective, here, we
investigate the global cosmological dynamics of the braneworld model using
dynamical system techniques. We first analyze the case where there is just a
normal matter on the brane and then extend the analysis to the case with an
extra scalar field also trapped on the brane. In the presence of a scalar
field, potentials belonging to different classes are considered. The stability
behavior of critical points is examined using linear stability analysis and
when necessary center manifold theory as well as numerical perturbation
techniques are also used. To understand the global dynamics of a dynamical
system, we utilized the Poincar\'e compactification method to capture the
properties of all possible critical points. Applying dynamical system analysis,
we found that brane gravity is consistent with observed actions of the
Universe. In particular, our analysis shows that important cosmological
behaviors like the long-lasting matter-dominated era, late time acceleration as
well as the avoidance of
Big-Rip singularity can be realized in brane gravity for a wide range of
initial conditions.
| [
{
"created": "Tue, 9 Oct 2018 04:57:18 GMT",
"version": "v1"
}
] | 2018-10-24 | [
[
"Zonunmawia",
"Hmar",
""
],
[
"Khyllep",
"Wompherdeiki",
""
],
[
"Dutta",
"Jibitesh",
""
],
[
"Järv",
"Laur",
""
]
] | The braneworld model of gravity is well-known for several notable cosmological features such as self-acceleration originating from a geometric and not matter source, effective dark energy behavior with phantom characteristics but not leading to a Big-Rip singularity, rough resemblance to the $\Lambda$CDM evolution, etc. The dynamical system tools usually allow us to obtain generic conclusions on the global dynamics of a system over a wide range of initial conditions. With this motivation, in order to recover the important features of the braneworld model from a more global perspective, here, we investigate the global cosmological dynamics of the braneworld model using dynamical system techniques. We first analyze the case where there is just a normal matter on the brane and then extend the analysis to the case with an extra scalar field also trapped on the brane. In the presence of a scalar field, potentials belonging to different classes are considered. The stability behavior of critical points is examined using linear stability analysis and when necessary center manifold theory as well as numerical perturbation techniques are also used. To understand the global dynamics of a dynamical system, we utilized the Poincar\'e compactification method to capture the properties of all possible critical points. Applying dynamical system analysis, we found that brane gravity is consistent with observed actions of the Universe. In particular, our analysis shows that important cosmological behaviors like the long-lasting matter-dominated era, late time acceleration as well as the avoidance of Big-Rip singularity can be realized in brane gravity for a wide range of initial conditions. |
1310.3120 | Mengyao Wang | Mengyao Wang, Haixing Miao, Andreas Freise, Yanbei Chen | Sensitivity of intracavity filtering schemes for detecting gravitational
waves | 10 pages, 10 figures | Phys. Rev. D 89, 062009 (2014) | 10.1103/PhysRevD.89.062009 | null | gr-qc physics.optics | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider enhancing the sensitivity of future gravitational-wave detectors
by adding optical filters inside the signal-recycling cavity -- an intracavity
filtering scheme, which coherently feeds the sideband signal back to the
interferometer with a proper frequency-dependent phase. We study three cases of
such a scheme with different motivations: (i) the case of backaction noise
evasion, trying to cancel radiation-pressure noise with only one filter cavity
for a signal-recycled interferometer; (ii) the speed-meter case, similar to the
speed-meter scheme proposed by Purdue and Chen [Phys. Rev. D 66, 122004 (2002)]
but without the resonant-sideband-extraction mirror, and also relieves the
optical requirement on the sloshing mirror; (iii) the broadband detection case
with squeezed-light input, numerically optimized for a broadband sensitivity.
| [
{
"created": "Fri, 11 Oct 2013 13:38:32 GMT",
"version": "v1"
},
{
"created": "Wed, 2 Apr 2014 13:06:49 GMT",
"version": "v2"
}
] | 2014-04-03 | [
[
"Wang",
"Mengyao",
""
],
[
"Miao",
"Haixing",
""
],
[
"Freise",
"Andreas",
""
],
[
"Chen",
"Yanbei",
""
]
] | We consider enhancing the sensitivity of future gravitational-wave detectors by adding optical filters inside the signal-recycling cavity -- an intracavity filtering scheme, which coherently feeds the sideband signal back to the interferometer with a proper frequency-dependent phase. We study three cases of such a scheme with different motivations: (i) the case of backaction noise evasion, trying to cancel radiation-pressure noise with only one filter cavity for a signal-recycled interferometer; (ii) the speed-meter case, similar to the speed-meter scheme proposed by Purdue and Chen [Phys. Rev. D 66, 122004 (2002)] but without the resonant-sideband-extraction mirror, and also relieves the optical requirement on the sloshing mirror; (iii) the broadband detection case with squeezed-light input, numerically optimized for a broadband sensitivity. |
2111.00106 | Hollis Williams | Hollis Williams | Recent Developments in the Penrose Conjecture | Corrected some errors and typos | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We survey recent developments towards a proof of the Penrose conjecture and
results on Penrose-type and other geometric inequalities for quasi-local masses
in general relativity.
| [
{
"created": "Fri, 29 Oct 2021 22:28:18 GMT",
"version": "v1"
},
{
"created": "Sat, 20 Nov 2021 15:18:03 GMT",
"version": "v2"
}
] | 2021-11-23 | [
[
"Williams",
"Hollis",
""
]
] | We survey recent developments towards a proof of the Penrose conjecture and results on Penrose-type and other geometric inequalities for quasi-local masses in general relativity. |
2205.08767 | Chunshan Lin | Robert Brandenberger, Paola C. M. Delgado, Alexander Ganz, Chunshan
Lin | Graviton to Photon Conversion via Parametric Resonance | 7 pages, 2 figures; v2 remarks added; v3 version accepted by Physics
of the Dark Universe | Physics of the Dark Universe, Volume 40, May 2023, 101202 | 10.1016/j.dark.2023.101202 | null | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | We study the parametric resonance excitation of the electromagnetic field by
a gravitational wave. We show that there is narrow band resonance. For an
electromagnetic field in the vacuum the resonance occurs only in the second
band, and its strength is thus suppressed by two powers of amplitude of the
gravitational wave. On the other hand, in the case of an electromagnetic field
in a medium with the speed of light smaller than 1 (in natural units), there is
a band of Fourier modes which undergo resonance in the first band.
| [
{
"created": "Wed, 18 May 2022 07:26:14 GMT",
"version": "v1"
},
{
"created": "Thu, 9 Jun 2022 09:44:10 GMT",
"version": "v2"
},
{
"created": "Tue, 28 Mar 2023 07:44:13 GMT",
"version": "v3"
}
] | 2023-03-29 | [
[
"Brandenberger",
"Robert",
""
],
[
"Delgado",
"Paola C. M.",
""
],
[
"Ganz",
"Alexander",
""
],
[
"Lin",
"Chunshan",
""
]
] | We study the parametric resonance excitation of the electromagnetic field by a gravitational wave. We show that there is narrow band resonance. For an electromagnetic field in the vacuum the resonance occurs only in the second band, and its strength is thus suppressed by two powers of amplitude of the gravitational wave. On the other hand, in the case of an electromagnetic field in a medium with the speed of light smaller than 1 (in natural units), there is a band of Fourier modes which undergo resonance in the first band. |
gr-qc/9712005 | Giuseppe Bimonte | G. Bimonte, S. Capozziello, V. Man'ko and G. Marmo | Cosmological waveguides for gravitational waves | 19 pages, compressed Latex file | Phys.Rev. D58 (1998) 104009 | 10.1103/PhysRevD.58.104009 | DSF-55/97, DSF-US11/97 | gr-qc hep-th | null | We study the linearized equations describing the propagation of gravitational
waves through dust. In the leading order of the WKB approximation, dust behaves
as a non-dispersive, non-dissipative medium. Taking advantage of these
features, we explore the possibility that a gravitational wave from a distant
source gets trapped by the gravitational field of a long filament of galaxies
of the kind seen in the large scale structure of the Universe. Such a
waveguiding effect may lead to a huge magnification of the radiation from
distant sources, thus lowering the sensitivity required for a successful
detection of gravitational waves by detectors like VIRGO, LIGO and LISA.
| [
{
"created": "Mon, 1 Dec 1997 10:21:22 GMT",
"version": "v1"
}
] | 2009-10-30 | [
[
"Bimonte",
"G.",
""
],
[
"Capozziello",
"S.",
""
],
[
"Man'ko",
"V.",
""
],
[
"Marmo",
"G.",
""
]
] | We study the linearized equations describing the propagation of gravitational waves through dust. In the leading order of the WKB approximation, dust behaves as a non-dispersive, non-dissipative medium. Taking advantage of these features, we explore the possibility that a gravitational wave from a distant source gets trapped by the gravitational field of a long filament of galaxies of the kind seen in the large scale structure of the Universe. Such a waveguiding effect may lead to a huge magnification of the radiation from distant sources, thus lowering the sensitivity required for a successful detection of gravitational waves by detectors like VIRGO, LIGO and LISA. |
gr-qc/0604030 | Muhammad Akbar Akbar | M. Akbar | symmetries of the Ricci tensor of static space times with maximal
symmetric transverse spaces | 11 pages | null | 10.1088/0253-6102/45/1/018 | null | gr-qc | null | Static space times with maximal symmetric transverse spaces are classified
according to their Ricci collineations. These are investigated for
non-degenerate Ricci tensor ($det.(R_{\alpha}) \neq 0$). It turns out that the
only collineations admitted by these spaces can be ten, seven, six or four.
Some new metrics admitting proper Ricci collineations are also investigated.
| [
{
"created": "Fri, 7 Apr 2006 04:10:23 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Akbar",
"M.",
""
]
] | Static space times with maximal symmetric transverse spaces are classified according to their Ricci collineations. These are investigated for non-degenerate Ricci tensor ($det.(R_{\alpha}) \neq 0$). It turns out that the only collineations admitted by these spaces can be ten, seven, six or four. Some new metrics admitting proper Ricci collineations are also investigated. |
1211.4365 | Maarten van de Meent | Maarten van de Meent | The Geometry of Massless Cosmic Strings | (13 pages, 4 figures) | Phys. Rev. D 87, 025020 (2013) | 10.1103/PhysRevD.87.025020 | ITP-UU-12/44 SPIN-12/41 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the geometry generated by a massless cosmic string. We find that
this is given by a Riemann flat spacetime with a conical singularity along the
worldsheet of the string. The geometry of such a spacetime is completely fixed
by the holonomy of a simple loop wrapping the conical singularity. In the case
of a massless cosmic string, this holonomy is a null-rotation/parabolic Lorentz
transformation with a parabolic angle given by the linear energy density of the
cosmic string. This description explicitly shows that there is no gravitational
shockwave accompanying the massless cosmic string as has been suggested in the
past. To illustrate the non-singular nature of the surrounding geometry, we
construct a metric for the massless cosmic string that is smooth everywhere
outside the conical singularity.
| [
{
"created": "Mon, 19 Nov 2012 11:27:16 GMT",
"version": "v1"
},
{
"created": "Tue, 29 Jan 2013 09:17:01 GMT",
"version": "v2"
}
] | 2013-01-30 | [
[
"van de Meent",
"Maarten",
""
]
] | We study the geometry generated by a massless cosmic string. We find that this is given by a Riemann flat spacetime with a conical singularity along the worldsheet of the string. The geometry of such a spacetime is completely fixed by the holonomy of a simple loop wrapping the conical singularity. In the case of a massless cosmic string, this holonomy is a null-rotation/parabolic Lorentz transformation with a parabolic angle given by the linear energy density of the cosmic string. This description explicitly shows that there is no gravitational shockwave accompanying the massless cosmic string as has been suggested in the past. To illustrate the non-singular nature of the surrounding geometry, we construct a metric for the massless cosmic string that is smooth everywhere outside the conical singularity. |
gr-qc/9703069 | Alejandro Jakubi | Luis P. Chimento and Alejandro S. Jakubi | Dissipative cosmological solutions | 17 pages, LaTeX 2.09, 1 figure. To be published in Classical and
Quantum Gravity | Class.Quant.Grav. 14 (1997) 1811-1820 | 10.1088/0264-9381/14/7/016 | null | gr-qc | null | The exact general solution to the Einstein equations in a homogeneous
Universe with a full causal viscous fluid source for the bulk viscosity index
$m=1/2$ is found. We have investigated the asymptotic stability of Friedmann
and de Sitter solutions, the former is stable for $m\ge 1/2$ and the latter for
$m\le 1/2$. The comparison with results of the truncated theory is made. For
$m=1/2$, it was found that families of solutions with extrema no longer remain
in the full case, and they are replaced by asymptotically Minkowski evolutions.
These solutions are monotonic.
| [
{
"created": "Tue, 25 Mar 1997 01:07:12 GMT",
"version": "v1"
}
] | 2009-10-30 | [
[
"Chimento",
"Luis P.",
""
],
[
"Jakubi",
"Alejandro S.",
""
]
] | The exact general solution to the Einstein equations in a homogeneous Universe with a full causal viscous fluid source for the bulk viscosity index $m=1/2$ is found. We have investigated the asymptotic stability of Friedmann and de Sitter solutions, the former is stable for $m\ge 1/2$ and the latter for $m\le 1/2$. The comparison with results of the truncated theory is made. For $m=1/2$, it was found that families of solutions with extrema no longer remain in the full case, and they are replaced by asymptotically Minkowski evolutions. These solutions are monotonic. |
1102.2663 | Roberto A. Sussman | Roberto A Sussman | Back-reaction and effective acceleration in generic LTB dust models | Final version accepted for publication in Classical and Quantum
Gravity. 47 pages in IOP LaTeX macros, 12 pdf figures | Classical and Quantum Gravity, vol 28, pp 235002 (2011) | 10.1088/0264-9381/28/23/235002 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide a thorough examination of the conditions for the existence of
back-reaction and an "effective" acceleration (in the context of Buchert's
averaging formalism) in regular generic spherically symmetric
Lemaitre-Tolman-Bondi (LTB) dust models. By considering arbitrary spherical
comoving domains, we verify rigorously the fulfillment of these conditions
expressed in terms of suitable scalar variables that are evaluated at the
boundary of every domain. Effective deceleration necessarily occurs in all
domains in: (a) the asymptotic radial range of models converging to a FLRW
background, (b) the asymptotic time range of non-vacuum hyperbolic models, (c)
LTB self-similar solutions and (d) near a simultaneous big bang. Accelerating
domains are proven to exist in the following scenarios: (i) central vacuum
regions, (ii) central (non-vacuum) density voids, (iii) the intermediate radial
range of models converging to a FLRW background, (iv) the asymptotic radial
range of models converging to a Minkowski vacuum and (v) domains near and/or
intersecting a non-simultaneous big bang. All these scenarios occur in
hyperbolic models with negative averaged and local spatial curvature, though
scenarios (iv) and (v) are also possible in low density regions of a class of
elliptic models in which local spatial curvature is negative but its average is
positive. Rough numerical estimates between -0.003 and -0.5 were found for the
effective deceleration parameter. While the existence of accelerating domains
cannot be ruled out in models converging to an Einstein de Sitter background
and in domains undergoing gravitational collapse, the conditions for this are
very restrictive. The results obtained may provide important theoretical clues
on the effects of back-reaction and averaging in more general non-spherical
models.
| [
{
"created": "Mon, 14 Feb 2011 02:31:08 GMT",
"version": "v1"
},
{
"created": "Thu, 13 Oct 2011 19:56:04 GMT",
"version": "v2"
}
] | 2015-05-27 | [
[
"Sussman",
"Roberto A",
""
]
] | We provide a thorough examination of the conditions for the existence of back-reaction and an "effective" acceleration (in the context of Buchert's averaging formalism) in regular generic spherically symmetric Lemaitre-Tolman-Bondi (LTB) dust models. By considering arbitrary spherical comoving domains, we verify rigorously the fulfillment of these conditions expressed in terms of suitable scalar variables that are evaluated at the boundary of every domain. Effective deceleration necessarily occurs in all domains in: (a) the asymptotic radial range of models converging to a FLRW background, (b) the asymptotic time range of non-vacuum hyperbolic models, (c) LTB self-similar solutions and (d) near a simultaneous big bang. Accelerating domains are proven to exist in the following scenarios: (i) central vacuum regions, (ii) central (non-vacuum) density voids, (iii) the intermediate radial range of models converging to a FLRW background, (iv) the asymptotic radial range of models converging to a Minkowski vacuum and (v) domains near and/or intersecting a non-simultaneous big bang. All these scenarios occur in hyperbolic models with negative averaged and local spatial curvature, though scenarios (iv) and (v) are also possible in low density regions of a class of elliptic models in which local spatial curvature is negative but its average is positive. Rough numerical estimates between -0.003 and -0.5 were found for the effective deceleration parameter. While the existence of accelerating domains cannot be ruled out in models converging to an Einstein de Sitter background and in domains undergoing gravitational collapse, the conditions for this are very restrictive. The results obtained may provide important theoretical clues on the effects of back-reaction and averaging in more general non-spherical models. |
gr-qc/9908076 | Hans-Juergen Schmidt | V. Dzhunushaliev, H.-J. Schmidt | 4D Wormhole with Signature Change in the Presence of Extra Dimensions | 8 pages, REVTeX, no figures | Grav.Cosmol. 5 (1999) 187-190 | null | Preprint UNIPO-MATH-99-Aug-31 | gr-qc | null | A regular vacuum solution in 5D gravity on the principal bundle with the U(1)
structural group is proposed as a 4D wormhole. This solution has two null
hypersurfaces where an interchange of the sign of some 5D metric components
happens. For a 4D observer living on the base of this principal bundle this is
a wormhole with two asymptotically flat Lorentzian (Euclidean) spacetimes
connected by a Euclidean (Lorentzian) throat. The 4D Lorentzian observer sees
these two null hypersurfaces as electric charges.
| [
{
"created": "Tue, 31 Aug 1999 07:15:40 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Dzhunushaliev",
"V.",
""
],
[
"Schmidt",
"H. -J.",
""
]
] | A regular vacuum solution in 5D gravity on the principal bundle with the U(1) structural group is proposed as a 4D wormhole. This solution has two null hypersurfaces where an interchange of the sign of some 5D metric components happens. For a 4D observer living on the base of this principal bundle this is a wormhole with two asymptotically flat Lorentzian (Euclidean) spacetimes connected by a Euclidean (Lorentzian) throat. The 4D Lorentzian observer sees these two null hypersurfaces as electric charges. |
2207.00846 | Deng Wang | Deng Wang | Testing the black hole area law with Event Horizon Telescope | 4 pages, 4 figs | null | 10.1209/0295-5075/acbe13 | null | gr-qc astro-ph.GA astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Hawking's black hole area theorem can be tested by monitoring the evolution
of a single black hole over time. Using current imaging observations of two
supermassive black holes M87* and Sgr A* from the Event Horizon Telescope
(EHT), we find their horizon area variation fractions are consistent with the
prediction of the black hole area law at the $1\,\sigma$ confidence level. We
point out that whether the black hole area law is valid or not could be
determined by future high precision EHT observations of Sgr A*.
| [
{
"created": "Sat, 2 Jul 2022 14:33:36 GMT",
"version": "v1"
}
] | 2023-03-15 | [
[
"Wang",
"Deng",
""
]
] | Hawking's black hole area theorem can be tested by monitoring the evolution of a single black hole over time. Using current imaging observations of two supermassive black holes M87* and Sgr A* from the Event Horizon Telescope (EHT), we find their horizon area variation fractions are consistent with the prediction of the black hole area law at the $1\,\sigma$ confidence level. We point out that whether the black hole area law is valid or not could be determined by future high precision EHT observations of Sgr A*. |
2306.10872 | Konstantinos Dialektopoulos F. | Konstantinos F. Dialektopoulos, Daniele Malafarina, Naresh Dadhich | Gravitational Collapse in pure Gauss-Bonnet gravity | 15 pages, 10 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the process of gravitational collapse in pure Gauss-Bonnet gravity.
In the homogeneous dust collapse, we show that the $D=7$ pure Gauss-Bonnet
theory has gravitational dynamics indistinguishable from Einstein's theory in
$D=4$, meaning that collapsing particle feel the same potential as in the
classical 4-dimensional general relativistic case. In $D<7$ pure Gauss-Bonnet
gravity becomes weaker, while in $D>7$ it becomes stronger, with respect to
General Relativity. In the inhomogeneous dust collapse we find the mass modes
in the expansion of the energy density in any dimensions that lead to either
naked singularities or black holes as final states of collapse.
| [
{
"created": "Mon, 19 Jun 2023 11:56:40 GMT",
"version": "v1"
}
] | 2023-06-21 | [
[
"Dialektopoulos",
"Konstantinos F.",
""
],
[
"Malafarina",
"Daniele",
""
],
[
"Dadhich",
"Naresh",
""
]
] | We study the process of gravitational collapse in pure Gauss-Bonnet gravity. In the homogeneous dust collapse, we show that the $D=7$ pure Gauss-Bonnet theory has gravitational dynamics indistinguishable from Einstein's theory in $D=4$, meaning that collapsing particle feel the same potential as in the classical 4-dimensional general relativistic case. In $D<7$ pure Gauss-Bonnet gravity becomes weaker, while in $D>7$ it becomes stronger, with respect to General Relativity. In the inhomogeneous dust collapse we find the mass modes in the expansion of the energy density in any dimensions that lead to either naked singularities or black holes as final states of collapse. |
1205.2166 | Philippe G. LeFloch | Ellery Ames, Florian Beyer, James Isenberg, and Philippe G. LeFloch | Quasi-linear symmetric hyperbolic Fuchsian systems in several space
dimensions | 21 pages | null | null | null | gr-qc math.AP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We establish existence and uniqueness results for the singular initial value
problem associated with a class of quasilinear, symmetric hyperbolic, partial
differential equations of Fuchsian type in several space dimensions. This is an
extension of earlier work by the authors for the same problem in one space
dimension.
| [
{
"created": "Thu, 10 May 2012 06:28:27 GMT",
"version": "v1"
},
{
"created": "Fri, 10 Aug 2012 16:46:57 GMT",
"version": "v2"
},
{
"created": "Wed, 5 Sep 2012 13:28:28 GMT",
"version": "v3"
}
] | 2012-09-06 | [
[
"Ames",
"Ellery",
""
],
[
"Beyer",
"Florian",
""
],
[
"Isenberg",
"James",
""
],
[
"LeFloch",
"Philippe G.",
""
]
] | We establish existence and uniqueness results for the singular initial value problem associated with a class of quasilinear, symmetric hyperbolic, partial differential equations of Fuchsian type in several space dimensions. This is an extension of earlier work by the authors for the same problem in one space dimension. |
gr-qc/0007047 | James Overduin | J. M. Overduin | Solar System Tests of the Equivalence Principle and Constraints on
Higher-Dimensional Gravity | 10 pages, 2 figs. LaTeX, uses PRD style files. To appear in PRD | Phys.Rev.D62:102001,2000 | 10.1103/PhysRevD.62.102001 | null | gr-qc | null | In most studies of equivalence principle violation by solar system bodies, it
is assumed that the ratio of gravitational to inertial mass for a given body
deviates from unity by a parameter Delta which is proportional to its
gravitational self-energy. Here we inquire what experimental constraints can be
set on Delta for various solar system objects when this assumption is relaxed.
Extending an analysis originally due to Nordtvedt, we obtain upper limits on
linearly independent combinations of Delta for two or more bodies from Kepler's
third law, the position of Lagrange libration points, and the phenomenon of
orbital polarization. Combining our results, we extract numerical upper bounds
on Delta for the Sun, Moon, Earth and Jupiter, using observational data on
their orbits as well as those of the Trojan asteroids. These are applied as a
test case to the theory of higher-dimensional (Kaluza-Klein) gravity. The
results are three to six orders of magnitude stronger than previous constraints
on the theory, confirming earlier suggestions that extra dimensions play a
negligible role in solar systemdynamics and reinforcing the value of
equivalence principle tests as a probe of nonstandard gravitational theories.
| [
{
"created": "Wed, 19 Jul 2000 18:46:18 GMT",
"version": "v1"
}
] | 2009-12-30 | [
[
"Overduin",
"J. M.",
""
]
] | In most studies of equivalence principle violation by solar system bodies, it is assumed that the ratio of gravitational to inertial mass for a given body deviates from unity by a parameter Delta which is proportional to its gravitational self-energy. Here we inquire what experimental constraints can be set on Delta for various solar system objects when this assumption is relaxed. Extending an analysis originally due to Nordtvedt, we obtain upper limits on linearly independent combinations of Delta for two or more bodies from Kepler's third law, the position of Lagrange libration points, and the phenomenon of orbital polarization. Combining our results, we extract numerical upper bounds on Delta for the Sun, Moon, Earth and Jupiter, using observational data on their orbits as well as those of the Trojan asteroids. These are applied as a test case to the theory of higher-dimensional (Kaluza-Klein) gravity. The results are three to six orders of magnitude stronger than previous constraints on the theory, confirming earlier suggestions that extra dimensions play a negligible role in solar systemdynamics and reinforcing the value of equivalence principle tests as a probe of nonstandard gravitational theories. |
gr-qc/0210104 | Vitorio A. De Lorenci | V. A. De Lorenci, R. Klippert, and Yu. N. Obukhov | On optical black holes in moving dielectrics | 5 pages, 2 figures, revtex4 | Phys.Rev. D68 (2003) 061502 | 10.1103/PhysRevD.68.061502 | null | gr-qc | null | We study the optical paths of the light rays propagating inside a nonlinear
moving dielectric media. For the rapidly moving dielectrics we show the
existence of a distinguished surface which resembles, as far as the light
propagation is concerned, the event horizon of a black hole. Our analysis
clarifies the physical conditions under which electromagnetic analogues of the
gravitational black holes can eventually be obtained in laboratory.
| [
{
"created": "Wed, 30 Oct 2002 15:04:57 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"De Lorenci",
"V. A.",
""
],
[
"Klippert",
"R.",
""
],
[
"Obukhov",
"Yu. N.",
""
]
] | We study the optical paths of the light rays propagating inside a nonlinear moving dielectric media. For the rapidly moving dielectrics we show the existence of a distinguished surface which resembles, as far as the light propagation is concerned, the event horizon of a black hole. Our analysis clarifies the physical conditions under which electromagnetic analogues of the gravitational black holes can eventually be obtained in laboratory. |
1904.00780 | Mauricio Bellini | Jes\'us Mart\'in Romero (IFIMAR, CONICET & UNMdP), Luis Santiago Ridao
(IFIMAR, CONICET & UNMdP), Mauricio Bellini (IFIMAR, CONICET & UNMdP) | Geometrization of gravito-electromagnetic interactions from boundary
conditions in the variational principle | improved version, 13 pages, no figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the conditions of integrability when the boundary terms are
considered in the variation of the geometric contribution of the
Einstein-Hilbert action. We explore the emergent physical dynamics that is
obtained when we make a displacement from a background Riemann manifold to an
extended one, on which the non-metricity is nonzero. Under these circumstances,
a classical description of electrodynamics and non-perturbative gravitational
waves are considered in the extended manifold, when we variate the action.
| [
{
"created": "Mon, 1 Apr 2019 12:42:57 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Jul 2019 21:27:00 GMT",
"version": "v2"
}
] | 2019-07-22 | [
[
"Romero",
"Jesús Martín",
"",
"IFIMAR, CONICET & UNMdP"
],
[
"Ridao",
"Luis Santiago",
"",
"IFIMAR, CONICET & UNMdP"
],
[
"Bellini",
"Mauricio",
"",
"IFIMAR, CONICET & UNMdP"
]
] | We study the conditions of integrability when the boundary terms are considered in the variation of the geometric contribution of the Einstein-Hilbert action. We explore the emergent physical dynamics that is obtained when we make a displacement from a background Riemann manifold to an extended one, on which the non-metricity is nonzero. Under these circumstances, a classical description of electrodynamics and non-perturbative gravitational waves are considered in the extended manifold, when we variate the action. |
2009.13587 | Leila Graef | L. N Barboza, L. L. Graef, Rudnei O. Ramos | Warm bounce in loop quantum cosmology and the prediction for the
duration of inflation | References added and some typos corrected with respect to the
published version | Phys. Rev. D 102, 103521 (2020) | 10.1103/PhysRevD.102.103521 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study and estimate probabilistic predictions for the duration of the
preinflationary and slow-roll phases after the bounce in loop quantum
cosmology, determining how the presence of radiation in the prebounce phase
affects these results. We present our analysis for different classes of
inflationary potentials that include the monomial power-law chaotic type of
potentials, namely, for the quadratic, quartic and sextic potentials and also
for a Higgs-like symmetry breaking potential, considering different values for
the vacuum expectation value in the latter case. We obtain the probability
density function for the number of inflationary e-folds and for other relevant
quantities for each model and produce probabilistic results drawn from these
distributions. This study allows us to discuss under which conditions each
model could eventually lead to observable signatures on the spectrum of the
cosmic microwave background, or, else, be also excluded for not predicting a
suffcient amount of accelerated expansion. The effect of radiation on the
predictions for each model is explicitly quantified. The obtained results
indicate that the number of inflationary e-folds in loop quantum cosmology is
not a priori an arbitrary number, but can in principle be a predictable
quantity, even though the results are dependent on the model and on the amount
of radiation in the Universe prior to the start of the inflationary regime.
| [
{
"created": "Mon, 28 Sep 2020 19:08:34 GMT",
"version": "v1"
},
{
"created": "Tue, 17 Nov 2020 19:14:22 GMT",
"version": "v2"
}
] | 2020-11-25 | [
[
"Barboza",
"L. N",
""
],
[
"Graef",
"L. L.",
""
],
[
"Ramos",
"Rudnei O.",
""
]
] | We study and estimate probabilistic predictions for the duration of the preinflationary and slow-roll phases after the bounce in loop quantum cosmology, determining how the presence of radiation in the prebounce phase affects these results. We present our analysis for different classes of inflationary potentials that include the monomial power-law chaotic type of potentials, namely, for the quadratic, quartic and sextic potentials and also for a Higgs-like symmetry breaking potential, considering different values for the vacuum expectation value in the latter case. We obtain the probability density function for the number of inflationary e-folds and for other relevant quantities for each model and produce probabilistic results drawn from these distributions. This study allows us to discuss under which conditions each model could eventually lead to observable signatures on the spectrum of the cosmic microwave background, or, else, be also excluded for not predicting a suffcient amount of accelerated expansion. The effect of radiation on the predictions for each model is explicitly quantified. The obtained results indicate that the number of inflationary e-folds in loop quantum cosmology is not a priori an arbitrary number, but can in principle be a predictable quantity, even though the results are dependent on the model and on the amount of radiation in the Universe prior to the start of the inflationary regime. |
2110.13140 | Andrey Nikitenko | A.A.Nikitenko | Some thermodynamic features in space-times with violation of causality | 2 pages, 1 figures | Gravitation and Cosmology. 27. 306-308 (2021) | 10.1134/S0202289321030105 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | General relativity does not prohibit the existence of space-times that
describe time travel. Consideration of such spaces gives rise to a lot of
questions and paradoxes, among which there are thermodynamic ones. This paper
considers two situations that describe time travel, and explains why their
existence does not mean that time machines are prohibited.
| [
{
"created": "Sun, 24 Oct 2021 13:13:37 GMT",
"version": "v1"
}
] | 2021-11-03 | [
[
"Nikitenko",
"A. A.",
""
]
] | General relativity does not prohibit the existence of space-times that describe time travel. Consideration of such spaces gives rise to a lot of questions and paradoxes, among which there are thermodynamic ones. This paper considers two situations that describe time travel, and explains why their existence does not mean that time machines are prohibited. |
2210.13481 | Pedro Luis Espino | Pedro Luis Espino, Gabriele Bozzola, Vasileios Paschalidis | Quantifying uncertainties in general relativistic magnetohydrodynamic
codes | null | null | 10.1103/PhysRevD.107.104059 | null | gr-qc astro-ph.HE astro-ph.SR hep-ph | http://creativecommons.org/licenses/by/4.0/ | In this paper, we show that similar open-source codes for general
relativistic magnetohydrodynamic (GRMHD) produce different results for key
features of binary neutron star mergers. First, we present a new open-source
version of the publicly available IllinoisGRMHD code that provides support for
realistic, finite temperature equations of state. After stringent tests of our
upgraded code, we perform a code comparison between GRHydro, IllinoisGRMHD,
Spritz, and WhiskyTHC, which implement the same physics, but slightly different
computational methods. The benefit of the comparison is that all codes are
embedded in the EinsteinToolkit suite, hence their only difference is
algorithmic. We find similar convergence properties, fluid dynamics, and
gravitational waves, but different merger times, remnant lifetimes, and
gravitational wave phases. Such differences must be resolved before the
post-merger dynamics modeled with such simulations can be reliably used to
infer the properties of nuclear matter especially in the era of precision
gravitational wave astronomy.
| [
{
"created": "Mon, 24 Oct 2022 18:00:01 GMT",
"version": "v1"
},
{
"created": "Wed, 26 Oct 2022 16:36:36 GMT",
"version": "v2"
}
] | 2023-06-14 | [
[
"Espino",
"Pedro Luis",
""
],
[
"Bozzola",
"Gabriele",
""
],
[
"Paschalidis",
"Vasileios",
""
]
] | In this paper, we show that similar open-source codes for general relativistic magnetohydrodynamic (GRMHD) produce different results for key features of binary neutron star mergers. First, we present a new open-source version of the publicly available IllinoisGRMHD code that provides support for realistic, finite temperature equations of state. After stringent tests of our upgraded code, we perform a code comparison between GRHydro, IllinoisGRMHD, Spritz, and WhiskyTHC, which implement the same physics, but slightly different computational methods. The benefit of the comparison is that all codes are embedded in the EinsteinToolkit suite, hence their only difference is algorithmic. We find similar convergence properties, fluid dynamics, and gravitational waves, but different merger times, remnant lifetimes, and gravitational wave phases. Such differences must be resolved before the post-merger dynamics modeled with such simulations can be reliably used to infer the properties of nuclear matter especially in the era of precision gravitational wave astronomy. |
gr-qc/0311031 | Fabio Postiglione | R. P. Croce (1), Th. Demma (1), V. Galdi (1), V. Pierro (1), I. M.
Pinto (1) and F. Postiglione (2) ((1) Univ. del Sannio at Benevento IT, (2)
D.I.I.I.E. Univ. di Salerno IT) | Rejection Properties of Stochastic-Resonance-Based Detectors of Weak
Harmonic Signals | 4 pages, 5 figures. Misprints corrected. PACS numbers added. RevTeX4 | Phys.Rev. E69 (2004) 062104 | 10.1103/PhysRevE.69.062104 | null | gr-qc | null | In (V. Galdi et al., Phys. Rev. E57, 6470, 1998) a thorough characterization
in terms of receiver operating characteristics (ROCs) of stochastic-resonance
(SR) detectors of weak harmonic signals of known frequency in additive gaussian
noise was given. It was shown that strobed sign-counting based strategies can
be used to achieve a nice trade-off between performance and cost, by comparison
with non-coherent correlators. Here we discuss the more realistic case where
besides the sought signal (whose frequency is assumed known) further unwanted
spectrally nearby signals with comparable amplitude are present. Rejection
properties are discussed in terms of suitably defined false-alarm and
false-dismissal probabilities for various values of interfering signal(s)
strength and spectral separation.
| [
{
"created": "Sat, 8 Nov 2003 22:50:07 GMT",
"version": "v1"
},
{
"created": "Wed, 16 Jun 2004 10:29:24 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Croce",
"R. P.",
""
],
[
"Demma",
"Th.",
""
],
[
"Galdi",
"V.",
""
],
[
"Pierro",
"V.",
""
],
[
"Pinto",
"I. M.",
""
],
[
"Postiglione",
"F.",
""
]
] | In (V. Galdi et al., Phys. Rev. E57, 6470, 1998) a thorough characterization in terms of receiver operating characteristics (ROCs) of stochastic-resonance (SR) detectors of weak harmonic signals of known frequency in additive gaussian noise was given. It was shown that strobed sign-counting based strategies can be used to achieve a nice trade-off between performance and cost, by comparison with non-coherent correlators. Here we discuss the more realistic case where besides the sought signal (whose frequency is assumed known) further unwanted spectrally nearby signals with comparable amplitude are present. Rejection properties are discussed in terms of suitably defined false-alarm and false-dismissal probabilities for various values of interfering signal(s) strength and spectral separation. |
1404.2850 | Gonzalo Olmo | Andrey N. Makarenko, Sergei D. Odintsov, Gonzalo J. Olmo | Little Rip, $\Lambda$CDM and singular dark energy cosmology from
Born-Infeld-$f(R)$ gravity | 7 pages, 5 figures. This version accepted in Phys. Lett. B | Phys.Lett. B734 (2014) 36-40 | 10.1016/j.physletb.2014.05.024 | IFIC/14-27 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study late-time cosmic accelerating dynamics from Born-Infeld-$f(R)$
gravity in a simplified conformal approach. We find that a variety of cosmic
efects such as Little Rip, $\Lambda$CDM universe and dark energy cosmology with
finite-time future singularities may occur. Unlike the convenient Born-Infeld
gravity where in the absence of matter only de Sitter expansion may emerge,
apparentlly any FRW cosmology maybe reconstructed from this conformal version
of the Born-Infeld-$f(R)$ theory. Despite the fact that the explicit form of
$f(R)$ is fixed by the conformal ansatz, the relation between the two metrics
in this approach may be changed so as to bring out any desired FRW cosmology.
| [
{
"created": "Thu, 10 Apr 2014 15:41:37 GMT",
"version": "v1"
},
{
"created": "Tue, 13 May 2014 19:31:54 GMT",
"version": "v2"
}
] | 2014-05-29 | [
[
"Makarenko",
"Andrey N.",
""
],
[
"Odintsov",
"Sergei D.",
""
],
[
"Olmo",
"Gonzalo J.",
""
]
] | We study late-time cosmic accelerating dynamics from Born-Infeld-$f(R)$ gravity in a simplified conformal approach. We find that a variety of cosmic efects such as Little Rip, $\Lambda$CDM universe and dark energy cosmology with finite-time future singularities may occur. Unlike the convenient Born-Infeld gravity where in the absence of matter only de Sitter expansion may emerge, apparentlly any FRW cosmology maybe reconstructed from this conformal version of the Born-Infeld-$f(R)$ theory. Despite the fact that the explicit form of $f(R)$ is fixed by the conformal ansatz, the relation between the two metrics in this approach may be changed so as to bring out any desired FRW cosmology. |
2111.08495 | Jay Solanki | Jay Solanki | Gravitational Collapse of Anisotropic Compact Stars in Modified $ f(R) $
Gravity | null | Eur. Phys. J. Plus 137, 557 (2022) | 10.1140/epjp/s13360-022-02784-7 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The physically realistic model of compact stars undergoing gravitational
collapse in $ f(R) $ gravity has been developed. We consider a more general
model $ R + f(R) = R + k R^m $ and describe the interior space-time of
gravitationally collapsing stars with separable-form of metric admitting
homothetic killing vector. We then investigate the junction conditions to match
the interior space-time with exterior space-time. Considering all junction
conditions, we find analytical solutions describing interior space-time metric,
energy density, pressures, and heat flux density of the compact stars
undergoing gravitational collapse. We impose the energy conditions to the model
for describing the realistic collapse of physically possible matter
distribution for particular models of $GR$, $ R+k R^2 $ and $ R+k R^4 $
gravity. The comprehensive graphical analysis of all energy conditions show
that the model is physically acceptable and realistic. We additionally
investigate the physical properties of collapsing stars which are useful to
decipher the inherent nature of such gravitationally collapsing stars.
| [
{
"created": "Mon, 15 Nov 2021 14:43:30 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Nov 2021 16:16:08 GMT",
"version": "v2"
}
] | 2022-05-17 | [
[
"Solanki",
"Jay",
""
]
] | The physically realistic model of compact stars undergoing gravitational collapse in $ f(R) $ gravity has been developed. We consider a more general model $ R + f(R) = R + k R^m $ and describe the interior space-time of gravitationally collapsing stars with separable-form of metric admitting homothetic killing vector. We then investigate the junction conditions to match the interior space-time with exterior space-time. Considering all junction conditions, we find analytical solutions describing interior space-time metric, energy density, pressures, and heat flux density of the compact stars undergoing gravitational collapse. We impose the energy conditions to the model for describing the realistic collapse of physically possible matter distribution for particular models of $GR$, $ R+k R^2 $ and $ R+k R^4 $ gravity. The comprehensive graphical analysis of all energy conditions show that the model is physically acceptable and realistic. We additionally investigate the physical properties of collapsing stars which are useful to decipher the inherent nature of such gravitationally collapsing stars. |
1611.00131 | Behnam Pourhassan | Behnam Pourhassan and Mir Faizal | Thermodynamics of a Sufficient Small Singly Spinning Kerr-AdS Black Hole | 21 pages, 11 figures. Accepted for publication in Nucl. Phys. B
(NUPHB 13899) | Nucl. Phys. B 913, 834 (2016) | 10.1016/j.nuclphysb.2016.10.013 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we will analyze the thermodynamics of a small singly spinning
Kerr-AdS black hole. As the black hole will be sufficient small, its
temperature will be large and so we can not neglect the effects of thermal
fluctuations. We will demonstrate that these thermal fluctuations correct the
entropy of singly spinning Kerr-AdS black hole by a logarithmic correction
term. We will analyze the implications of the logarithmic correction on other
thermodynamic properties of this black hole, and analyze the stability of such
a black hole. We will observe that this form of correction becomes important
when the size of the black hole is sufficient small. We will also analyze the
effect of these thermal fluctuations on the critical phenomena for such a black
hole.
| [
{
"created": "Tue, 1 Nov 2016 05:29:43 GMT",
"version": "v1"
}
] | 2016-11-14 | [
[
"Pourhassan",
"Behnam",
""
],
[
"Faizal",
"Mir",
""
]
] | In this paper, we will analyze the thermodynamics of a small singly spinning Kerr-AdS black hole. As the black hole will be sufficient small, its temperature will be large and so we can not neglect the effects of thermal fluctuations. We will demonstrate that these thermal fluctuations correct the entropy of singly spinning Kerr-AdS black hole by a logarithmic correction term. We will analyze the implications of the logarithmic correction on other thermodynamic properties of this black hole, and analyze the stability of such a black hole. We will observe that this form of correction becomes important when the size of the black hole is sufficient small. We will also analyze the effect of these thermal fluctuations on the critical phenomena for such a black hole. |
2408.07617 | Katy Clough Dr | Katy Clough | New Horizons for Psi: Studying fundamental fields with numerical
relativity | Comments welcome. 20 pages, 5 figures. See
https://github.com/GRTLCollaboration/engrenage/wiki/New-Horizons-for-Psi-workshop
for supporting material | null | null | null | gr-qc astro-ph.CO hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This set of notes was designed to accompany two hours of lectures and
practical exercises at the New Horizons for Psi workshop in Lisbon in July 2024
entitled "Studying fundamental fields with numerical relativity". Numerical
relativity is a tool used to help understand the behaviours of metric and
matter fields in dynamical, strong gravity situations. It has been used to
study a range of situations involving fundamental fields, including
superradiance, modified gravity, dynamical friction, dark matter accretion and
early universe cosmology. The purpose of this course is to provide some
background and hands-on experience in numerical relativity that will help
students to better understand the possibilities provided by this tool, as well
as its limitations.
| [
{
"created": "Wed, 14 Aug 2024 15:32:10 GMT",
"version": "v1"
}
] | 2024-08-15 | [
[
"Clough",
"Katy",
""
]
] | This set of notes was designed to accompany two hours of lectures and practical exercises at the New Horizons for Psi workshop in Lisbon in July 2024 entitled "Studying fundamental fields with numerical relativity". Numerical relativity is a tool used to help understand the behaviours of metric and matter fields in dynamical, strong gravity situations. It has been used to study a range of situations involving fundamental fields, including superradiance, modified gravity, dynamical friction, dark matter accretion and early universe cosmology. The purpose of this course is to provide some background and hands-on experience in numerical relativity that will help students to better understand the possibilities provided by this tool, as well as its limitations. |
gr-qc/9208011 | null | Jong H. Kung | Comparison of the Sachs-Wolfe Effect for Gaussian and Non-Gaussian
Fluctuations | 16 pages | Phys.Rev.D47:409-415,1993 | 10.1103/PhysRevD.47.409 | report # CfA 3435 | gr-qc astro-ph | null | A consequence of non-Gaussian perturbations on the Sachs-Wolfe effect is
studied. For a particular power spectrum, predicted Sachs-Wolfe effects are
calculated for two cases: Gaussian (random phase) configuration, and a specific
kind of non-Gaussian configuration. We obtain a result that the Sachs-Wolfe
effect for the latter case is smaller when each temperature fluctuation is
properly normalized with respect to the corresponding mass fluctuation ${\delta
M\over M}(R)$. The physical explanation and the generality of the result are
discussed.
| [
{
"created": "Fri, 28 Aug 1992 17:36:37 GMT",
"version": "v1"
}
] | 2009-12-30 | [
[
"Kung",
"Jong H.",
""
]
] | A consequence of non-Gaussian perturbations on the Sachs-Wolfe effect is studied. For a particular power spectrum, predicted Sachs-Wolfe effects are calculated for two cases: Gaussian (random phase) configuration, and a specific kind of non-Gaussian configuration. We obtain a result that the Sachs-Wolfe effect for the latter case is smaller when each temperature fluctuation is properly normalized with respect to the corresponding mass fluctuation ${\delta M\over M}(R)$. The physical explanation and the generality of the result are discussed. |
1908.10316 | Pierre-Henri Chavanis | Giuseppe Alberti and Pierre-Henri Chavanis | Caloric curves of classical self-gravitating systems in general
relativity | null | Phys. Rev. E 101, 052105 (2020) | 10.1103/PhysRevE.101.052105 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We determine the caloric curves of classical self-gravitating systems at
statistical equilibrium in general relativity. In the classical limit, the
caloric curves of a self-gravitating gas depend on a unique parameter
$\nu=GNm/Rc^2$, called the compactness parameter, where $N$ is the particle
number and $R$ the system's size. Typically, the caloric curves have the form
of a double spiral. The "cold spiral", corresponding to weakly relativistic
configurations, is a generalization of the caloric curve of nonrelativistic
classical self-gravitating systems. The "hot spiral'", corresponding to
strongly relativistic configurations, is similar (but not identical) to the
caloric curve of the ultrarelativistic self-gravitating black-body radiation.
We introduce two types of normalization of energy and temperature in order to
obtain asymptotic caloric curves describing respectively the cold and the hot
spirals in the limit $\nu\rightarrow 0$. As the number of particles increases,
the cold and the hot spirals approach each other, merge at $\nu'_S=0.128$, form
a loop above $\nu_S=0.1415$, reduce to a point at $\nu_{\rm max}=0.1764$, and
finally disappear. Therefore, the double spiral shrinks when the compactness
parameter $\nu$ increases, implying that general relativistic effects render
the system more unstable. We discuss the nature of the gravitational collapse
at low and high energies with respect to a dynamical (fast) or a
thermodynamical (slow) instability.
| [
{
"created": "Tue, 27 Aug 2019 16:44:40 GMT",
"version": "v1"
}
] | 2020-05-20 | [
[
"Alberti",
"Giuseppe",
""
],
[
"Chavanis",
"Pierre-Henri",
""
]
] | We determine the caloric curves of classical self-gravitating systems at statistical equilibrium in general relativity. In the classical limit, the caloric curves of a self-gravitating gas depend on a unique parameter $\nu=GNm/Rc^2$, called the compactness parameter, where $N$ is the particle number and $R$ the system's size. Typically, the caloric curves have the form of a double spiral. The "cold spiral", corresponding to weakly relativistic configurations, is a generalization of the caloric curve of nonrelativistic classical self-gravitating systems. The "hot spiral'", corresponding to strongly relativistic configurations, is similar (but not identical) to the caloric curve of the ultrarelativistic self-gravitating black-body radiation. We introduce two types of normalization of energy and temperature in order to obtain asymptotic caloric curves describing respectively the cold and the hot spirals in the limit $\nu\rightarrow 0$. As the number of particles increases, the cold and the hot spirals approach each other, merge at $\nu'_S=0.128$, form a loop above $\nu_S=0.1415$, reduce to a point at $\nu_{\rm max}=0.1764$, and finally disappear. Therefore, the double spiral shrinks when the compactness parameter $\nu$ increases, implying that general relativistic effects render the system more unstable. We discuss the nature of the gravitational collapse at low and high energies with respect to a dynamical (fast) or a thermodynamical (slow) instability. |
gr-qc/0312088 | Joseph Romano | LIGO Scientific Collaboration: B. Abbott, et al | Analysis of First LIGO Science Data for Stochastic Gravitational Waves | 26 pages, 17 figures | Phys.Rev.D69:122004,2004 | 10.1103/PhysRevD.69.122004 | null | gr-qc | null | We present the analysis of between 50 and 100 hrs of coincident
interferometric strain data used to search for and establish an upper limit on
a stochastic background of gravitational radiation. These data come from the
first LIGO science run, during which all three LIGO interferometers were
operated over a 2-week period spanning August and September of 2002. The method
of cross-correlating the outputs of two interferometers is used for analysis.
We describe in detail practical signal processing issues that arise when
working with real data, and we establish an observational upper limit on a
f^{-3} power spectrum of gravitational waves. Our 90% confidence limit is
Omega_0 h_{100}^2 < 23 in the frequency band 40 to 314 Hz, where h_{100} is the
Hubble constant in units of 100 km/sec/Mpc and Omega_0 is the gravitational
wave energy density per logarithmic frequency interval in units of the closure
density. This limit is approximately 10^4 times better than the previous,
broadband direct limit using interferometric detectors, and nearly 3 times
better than the best narrow-band bar detector limit. As LIGO and other
worldwide detectors improve in sensitivity and attain their design goals, the
analysis procedures described here should lead to stochastic background
sensitivity levels of astrophysical interest.
| [
{
"created": "Fri, 19 Dec 2003 18:00:01 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"LIGO Scientific Collaboration",
"",
""
],
[
"Abbott",
"B.",
""
]
] | We present the analysis of between 50 and 100 hrs of coincident interferometric strain data used to search for and establish an upper limit on a stochastic background of gravitational radiation. These data come from the first LIGO science run, during which all three LIGO interferometers were operated over a 2-week period spanning August and September of 2002. The method of cross-correlating the outputs of two interferometers is used for analysis. We describe in detail practical signal processing issues that arise when working with real data, and we establish an observational upper limit on a f^{-3} power spectrum of gravitational waves. Our 90% confidence limit is Omega_0 h_{100}^2 < 23 in the frequency band 40 to 314 Hz, where h_{100} is the Hubble constant in units of 100 km/sec/Mpc and Omega_0 is the gravitational wave energy density per logarithmic frequency interval in units of the closure density. This limit is approximately 10^4 times better than the previous, broadband direct limit using interferometric detectors, and nearly 3 times better than the best narrow-band bar detector limit. As LIGO and other worldwide detectors improve in sensitivity and attain their design goals, the analysis procedures described here should lead to stochastic background sensitivity levels of astrophysical interest. |
1311.4051 | Puxun Wu | Kaituo Zhang, Puxun Wu and Hongwei Yu | Emergent universe in spatially flat cosmological model | 16 pages, 8 figures | JCAP01(2014)048 | 10.1088/1475-7516/2014/01/048 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The scenario of an emergent universe provides a promising resolution to the
big bang singularity in universes with positive or negative spatial curvature.
It however remains unclear whether the scenario can be successfully implemented
in a spatially flat universe which seems to be favored by present cosmological
observations. In this paper, we study the stability of Einstein static state
solutions in a spatially flat Shtanov-Sahni braneworld scenario. With a
negative dark radiation term included and assuming a scalar field as the only
matter energy component, we find that the universe can stay at an Einstein
static state past eternally and then evolve to an inflation phase naturally as
the scalar field climbs up its potential slowly. In addition, we also propose a
concrete potential of the scalar field that realizes this scenario.
| [
{
"created": "Sat, 16 Nov 2013 12:28:45 GMT",
"version": "v1"
},
{
"created": "Tue, 11 Feb 2014 11:10:14 GMT",
"version": "v2"
}
] | 2015-06-17 | [
[
"Zhang",
"Kaituo",
""
],
[
"Wu",
"Puxun",
""
],
[
"Yu",
"Hongwei",
""
]
] | The scenario of an emergent universe provides a promising resolution to the big bang singularity in universes with positive or negative spatial curvature. It however remains unclear whether the scenario can be successfully implemented in a spatially flat universe which seems to be favored by present cosmological observations. In this paper, we study the stability of Einstein static state solutions in a spatially flat Shtanov-Sahni braneworld scenario. With a negative dark radiation term included and assuming a scalar field as the only matter energy component, we find that the universe can stay at an Einstein static state past eternally and then evolve to an inflation phase naturally as the scalar field climbs up its potential slowly. In addition, we also propose a concrete potential of the scalar field that realizes this scenario. |
0904.4368 | Harvey S. Reall | Mahdi Godazgar, Harvey S. Reall | Algebraically special axisymmetric solutions of the higher-dimensional
vacuum Einstein equation | 28 pages | Class.Quant.Grav.26:165009,2009 | 10.1088/0264-9381/26/16/165009 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A d-dimensional spacetime is "axisymmetric" if it possesses an SO(d-2)
isometry group whose orbits are (d-3)-spheres. In this paper, algebraically
special, axisymmetric solutions of the higher dimensional vacuum Einstein
equation (with cosmological constant) are investigated. Necessary and
sufficient conditions for static axisymmetric solutions to belong to different
algebraic classes are presented. Then general (possibly time-dependent)
axisymmetric solutions are discussed. All axisymmetric solutions of algebraic
types II, D, III and N are obtained.
| [
{
"created": "Tue, 28 Apr 2009 11:34:59 GMT",
"version": "v1"
}
] | 2009-11-19 | [
[
"Godazgar",
"Mahdi",
""
],
[
"Reall",
"Harvey S.",
""
]
] | A d-dimensional spacetime is "axisymmetric" if it possesses an SO(d-2) isometry group whose orbits are (d-3)-spheres. In this paper, algebraically special, axisymmetric solutions of the higher dimensional vacuum Einstein equation (with cosmological constant) are investigated. Necessary and sufficient conditions for static axisymmetric solutions to belong to different algebraic classes are presented. Then general (possibly time-dependent) axisymmetric solutions are discussed. All axisymmetric solutions of algebraic types II, D, III and N are obtained. |
1911.06183 | Ignazio Ciufolini | Ignazio Ciufolini, Erricos C. Pavlis, Giampiero Sindoni, John Ries,
Antonio Paolozzi, Rolf Koenig, Richard Matzner | A new laser-ranged satellite for General Relativity and Space Geodesy
II. Monte Carlo Simulations and covariance analyses of the LARES 2 Experiment | 15 pages and 6 figures. arXiv admin note: text overlap with
arXiv:1310.2601 | Eur. Phys. J. Plus (2017) 132: 337 | 10.1140/epjp/i2017-11636-0 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the previous paper we have introduced the LARES 2 space experiment. The
LARES 2 laser-ranged satellite is planned for a launch in 2019 with the new
VEGA C launch vehicle of the Italian Space Agency (ASI), ESA and ELV. The main
objectives of the LARES 2 experiment are accurate measurements of General
Relativity, gravitational and fundamental physics and accurate determinations
in space geodesy and geodynamics. In particular LARES 2 is aimed to achieve a
very accurate test of frame-dragging, an intriguing phenomenon predicted by
General Relativity. Here we report the results of Monte Carlo simulations and
covariance analyses fully confirming an error budget of a few parts in one
thousand in the measurement of frame-dragging with LARES 2 as calculated in our
previous paper.
| [
{
"created": "Tue, 12 Nov 2019 14:39:30 GMT",
"version": "v1"
}
] | 2019-11-15 | [
[
"Ciufolini",
"Ignazio",
""
],
[
"Pavlis",
"Erricos C.",
""
],
[
"Sindoni",
"Giampiero",
""
],
[
"Ries",
"John",
""
],
[
"Paolozzi",
"Antonio",
""
],
[
"Koenig",
"Rolf",
""
],
[
"Matzner",
"Richard",
""
]
... | In the previous paper we have introduced the LARES 2 space experiment. The LARES 2 laser-ranged satellite is planned for a launch in 2019 with the new VEGA C launch vehicle of the Italian Space Agency (ASI), ESA and ELV. The main objectives of the LARES 2 experiment are accurate measurements of General Relativity, gravitational and fundamental physics and accurate determinations in space geodesy and geodynamics. In particular LARES 2 is aimed to achieve a very accurate test of frame-dragging, an intriguing phenomenon predicted by General Relativity. Here we report the results of Monte Carlo simulations and covariance analyses fully confirming an error budget of a few parts in one thousand in the measurement of frame-dragging with LARES 2 as calculated in our previous paper. |
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