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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1005.3679 | Rolando Gaitan Deveras RGD | Rolando Gaitan Deveras | On unitarity of a Yang-Mills type formulation for massless and massive
gravity with propagating torsion | 28 p | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A perturbative regime based on contorsion as a dynamical variable and metric
as a (classical) fixed background, is performed in the context of a pure
Yang-Mills formulation based on $GL(3,R)$ gauge group. In the massless case we
show that the theory propagates three degrees of freedom and only one is a
non-unitary mode. Next, we introduce quadratical terms dependent on torsion,
which preserve parity and general covariance. The linearized version reproduces
an analogue Hilbert-Einstein-Fierz-Pauli unitary massive theory plus three
massless modes, two of them non-unitary ones. Finally we confirm the existence
of a family of unitary Yang-Mills-extended theories which are classically
consistent with Einstein's solutions coming from non massive and topologically
massive gravity.
| [
{
"created": "Thu, 20 May 2010 12:33:47 GMT",
"version": "v1"
}
] | 2010-05-21 | [
[
"Deveras",
"Rolando Gaitan",
""
]
] | A perturbative regime based on contorsion as a dynamical variable and metric as a (classical) fixed background, is performed in the context of a pure Yang-Mills formulation based on $GL(3,R)$ gauge group. In the massless case we show that the theory propagates three degrees of freedom and only one is a non-unitary mode. Next, we introduce quadratical terms dependent on torsion, which preserve parity and general covariance. The linearized version reproduces an analogue Hilbert-Einstein-Fierz-Pauli unitary massive theory plus three massless modes, two of them non-unitary ones. Finally we confirm the existence of a family of unitary Yang-Mills-extended theories which are classically consistent with Einstein's solutions coming from non massive and topologically massive gravity. |
1409.4431 | Michael Boyle | Michael Boyle, Lawrence E. Kidder, Serguei Ossokine, and Harald P.
Pfeiffer | Gravitational-wave modes from precessing black-hole binaries | Updated a few URLs to point to the code accompanying the paper | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational waves from precessing black-hole binaries exhibit features that
are absent in nonprecessing systems. The most prominent of these is a
parity-violating asymmetry that beams energy and linear momentum preferentially
along or opposite to the orbital angular momentum, leading to recoil of the
binary. The asymmetry will appear as amplitude and phase modulations at the
orbital frequency. For strongly precessing systems, it accounts for at least 3%
amplitude modulation for binaries in the sensitivity band of ground-based
gravitational-wave detectors, and can exceed 50% for massive systems. Such
asymmetric features are also clearly visible when the waves are decomposed into
modes of spin-weighted spherical harmonics, and are inherent in the waves
themselves---rather than resulting from residual eccentricity in numerical
simulations, or from mode-mixing due to precession. In particular, there is
generically no instantaneous frame for which the mode decomposition will have
any symmetry. We introduce a method to simplify the expressions for waveforms
given in analytical relativity, which can be used to combine existing
high-order waveforms for nonprecessing systems with expressions for the
precessing contributions, leading to improved accuracy and a unified treatment
of precessing and nonprecessing binaries. Using this method, it is possible to
clarify the nature and the origins of the asymmetries and show the effects of
asymmetry on recoils more clearly. We present post-Newtonian (PN) expressions
for the waveform modes that include these terms, complete to the relative 2PN
level in spin (proportional to $v^4/c^4$ times a certain combination of the
spins). Comparing the results of those expressions to numerical results, we
find good qualitative agreement. We also demonstrate how these expressions can
be used to efficiently calculate waveforms for gravitational-wave astronomy.
| [
{
"created": "Mon, 15 Sep 2014 20:03:36 GMT",
"version": "v1"
},
{
"created": "Mon, 22 Sep 2014 20:46:18 GMT",
"version": "v2"
}
] | 2014-09-24 | [
[
"Boyle",
"Michael",
""
],
[
"Kidder",
"Lawrence E.",
""
],
[
"Ossokine",
"Serguei",
""
],
[
"Pfeiffer",
"Harald P.",
""
]
] | Gravitational waves from precessing black-hole binaries exhibit features that are absent in nonprecessing systems. The most prominent of these is a parity-violating asymmetry that beams energy and linear momentum preferentially along or opposite to the orbital angular momentum, leading to recoil of the binary. The asymmetry will appear as amplitude and phase modulations at the orbital frequency. For strongly precessing systems, it accounts for at least 3% amplitude modulation for binaries in the sensitivity band of ground-based gravitational-wave detectors, and can exceed 50% for massive systems. Such asymmetric features are also clearly visible when the waves are decomposed into modes of spin-weighted spherical harmonics, and are inherent in the waves themselves---rather than resulting from residual eccentricity in numerical simulations, or from mode-mixing due to precession. In particular, there is generically no instantaneous frame for which the mode decomposition will have any symmetry. We introduce a method to simplify the expressions for waveforms given in analytical relativity, which can be used to combine existing high-order waveforms for nonprecessing systems with expressions for the precessing contributions, leading to improved accuracy and a unified treatment of precessing and nonprecessing binaries. Using this method, it is possible to clarify the nature and the origins of the asymmetries and show the effects of asymmetry on recoils more clearly. We present post-Newtonian (PN) expressions for the waveform modes that include these terms, complete to the relative 2PN level in spin (proportional to $v^4/c^4$ times a certain combination of the spins). Comparing the results of those expressions to numerical results, we find good qualitative agreement. We also demonstrate how these expressions can be used to efficiently calculate waveforms for gravitational-wave astronomy. |
1207.5241 | Shun-Pei Miao | S. P. Miao | Quantum Gravitational Effects on Massive Fermions during Inflation I | 81 pages, 3 figures, 42 tables, a modified version with several
references added. arXiv admin note: substantial text overlap with
arXiv:gr-qc/0511140 | Phys. Rev. D86 (2012) 104051 | 10.1103/PhysRevD.86.104051 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compute the one loop graviton contribution to the self-energy of a very
light fermion on a locally de Sitter background. This result can be used to
study the effect that a small mass has on the propagation of fermions through
the sea of infrared gravitons generated by inflation. We employ dimensional
regularization and obtain a fully renormalized result by absorbing all
divergences with BPHZ counterterms. An interesting technical aspect of this
computation is the need for two noninvariant counterterms owing to the breaking
of de Sitter invariance by our gauge condition.
| [
{
"created": "Sun, 22 Jul 2012 16:49:16 GMT",
"version": "v1"
},
{
"created": "Mon, 3 Dec 2012 23:05:39 GMT",
"version": "v2"
}
] | 2015-06-05 | [
[
"Miao",
"S. P.",
""
]
] | We compute the one loop graviton contribution to the self-energy of a very light fermion on a locally de Sitter background. This result can be used to study the effect that a small mass has on the propagation of fermions through the sea of infrared gravitons generated by inflation. We employ dimensional regularization and obtain a fully renormalized result by absorbing all divergences with BPHZ counterterms. An interesting technical aspect of this computation is the need for two noninvariant counterterms owing to the breaking of de Sitter invariance by our gauge condition. |
gr-qc/9603031 | Douglas A. Singleton | Douglas Singleton | Yang-Mills Inspired Solutions for General Relativity | 13 pages LaTeX | Phys.Lett. A223 (1996) 12-18 | 10.1016/S0375-9601(96)00700-1 | null | gr-qc | null | Several exact, cylindrically symmetric solutions to Einstein's vacuum
equations are given. These solutions were found using the connection between
Yang-Mills theory and general relativity. Taking known solutions of the
Yang-Mills equations (e.g. the topological BPS monopole solutions) it is
possible to construct exact solutions to the general relativistic field
equations. Although the general relativistic solutions were found starting from
known solutions of Yang-Mills theory they have different physical
characteristics.
| [
{
"created": "Thu, 21 Mar 1996 02:46:01 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Singleton",
"Douglas",
""
]
] | Several exact, cylindrically symmetric solutions to Einstein's vacuum equations are given. These solutions were found using the connection between Yang-Mills theory and general relativity. Taking known solutions of the Yang-Mills equations (e.g. the topological BPS monopole solutions) it is possible to construct exact solutions to the general relativistic field equations. Although the general relativistic solutions were found starting from known solutions of Yang-Mills theory they have different physical characteristics. |
2208.03629 | Xue Zheng Zhu | Xue-Zheng Zhu and Yang Yu and Xian Gao | Cosmological perturbations in the spatially covariant gravity with a
dynamical lapse function | null | Phys.Lett.B 833 (2022) 137356 | 10.1016/j.physletb.2022.137356 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the scalar perturbations in a class of spatially covariant
gravity theory with a dynamical lapse function.
Generally, there are two scalar degrees of freedom due to the presence of the
velocity of the lapse function.
We treat the scalar perturbations as analogues of those in a two-field
inflationary mode, in which one is light mode and the other is the heavy mode.
This is justified by the fact that the scalar mode due to the dynamical lapse
function becomes infinitely heavy in the limit when the lapse function reduces
to be an auxiliary variable.
The standard approaches of multiple filed perturbations can be applied to
deal with our model.
By integrating out the heavy mode and derive the effective theory for the
single light field, we find the solution to the single mode in the form of
plane waves.
Then we calculate the corrections to the power spectrum of the light mode
from the heavy mode, by making use of the standard perturbative method of field
theory.
At last, when the two fields are not weakly coupled, we find a power law mode
for the coupled system in large scales.
| [
{
"created": "Sun, 7 Aug 2022 03:45:25 GMT",
"version": "v1"
}
] | 2022-08-10 | [
[
"Zhu",
"Xue-Zheng",
""
],
[
"Yu",
"Yang",
""
],
[
"Gao",
"Xian",
""
]
] | We investigate the scalar perturbations in a class of spatially covariant gravity theory with a dynamical lapse function. Generally, there are two scalar degrees of freedom due to the presence of the velocity of the lapse function. We treat the scalar perturbations as analogues of those in a two-field inflationary mode, in which one is light mode and the other is the heavy mode. This is justified by the fact that the scalar mode due to the dynamical lapse function becomes infinitely heavy in the limit when the lapse function reduces to be an auxiliary variable. The standard approaches of multiple filed perturbations can be applied to deal with our model. By integrating out the heavy mode and derive the effective theory for the single light field, we find the solution to the single mode in the form of plane waves. Then we calculate the corrections to the power spectrum of the light mode from the heavy mode, by making use of the standard perturbative method of field theory. At last, when the two fields are not weakly coupled, we find a power law mode for the coupled system in large scales. |
2105.06223 | David McNutt | D. D. McNutt, A. A. Coley and R. J. van den Hoogen | Teleparallel geometries not characterized by their scalar polynomial
torsion invariants | 3o pages, 1 figure | Journal of Mathematical Physics, 62, 052501 (2021) | 10.1063/5.0051400 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A teleparallel geometry is an n-dimensional manifold equipped with a frame
basis and an independent spin connection. For such a geometry, the curvature
tensor vanishes and the torsion tensor is non-zero. A straightforward approach
to characterizing teleparallel geometries is to compute scalar polynomial
invariants constructed from the torsion tensor and its covariant derivatives.
An open question has been whether the set of all scalar polynomial torsion
invariants, $\mathcal{I}_T$ uniquely characterize a given teleparallel
geometry. In this paper we show that the answer is no and construct the most
general class of teleparallel geometries in four dimensions which cannot be
characterized by $\mathcal{I}_T$. As a corollary we determine all teleparallel
geometries which have vanishing scalar polynomial torsion invariants.
| [
{
"created": "Thu, 13 May 2021 12:22:59 GMT",
"version": "v1"
}
] | 2021-05-14 | [
[
"McNutt",
"D. D.",
""
],
[
"Coley",
"A. A.",
""
],
[
"Hoogen",
"R. J. van den",
""
]
] | A teleparallel geometry is an n-dimensional manifold equipped with a frame basis and an independent spin connection. For such a geometry, the curvature tensor vanishes and the torsion tensor is non-zero. A straightforward approach to characterizing teleparallel geometries is to compute scalar polynomial invariants constructed from the torsion tensor and its covariant derivatives. An open question has been whether the set of all scalar polynomial torsion invariants, $\mathcal{I}_T$ uniquely characterize a given teleparallel geometry. In this paper we show that the answer is no and construct the most general class of teleparallel geometries in four dimensions which cannot be characterized by $\mathcal{I}_T$. As a corollary we determine all teleparallel geometries which have vanishing scalar polynomial torsion invariants. |
gr-qc/0009069 | Tekin Dereli | H. Cebeci, T. Dereli (METU) | Conformal Black Hole Solutions of Axi-Dilaton Gravity in D-dimensions | 6 PAGES, Rev-tex file, no figures, to appear in Phys-Rev D | Phys.Rev. D65 (2002) 047501 | 10.1103/PhysRevD.65.047501 | null | gr-qc | null | Static, spherically symmetric solutions of axi-dilaton gravity in $D$
dimensions is given in the Brans-Dicke frame for arbitrary values of the
Brans-Dicke constant $\omega$ and an axion-dilaton coupling parameter $k$. The
mass and the dilaton and axion charges are determined and a BPS bound is
derived. There exists a one parameter family of black hole solutions in the
scale invariant limit.
| [
{
"created": "Tue, 19 Sep 2000 15:39:43 GMT",
"version": "v1"
},
{
"created": "Wed, 26 Sep 2001 19:11:13 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Cebeci",
"H.",
"",
"METU"
],
[
"Dereli",
"T.",
"",
"METU"
]
] | Static, spherically symmetric solutions of axi-dilaton gravity in $D$ dimensions is given in the Brans-Dicke frame for arbitrary values of the Brans-Dicke constant $\omega$ and an axion-dilaton coupling parameter $k$. The mass and the dilaton and axion charges are determined and a BPS bound is derived. There exists a one parameter family of black hole solutions in the scale invariant limit. |
gr-qc/0110031 | Dumitru Vulcanov | Dumitru N. Vulcanov, Miguel Alcubierre (Max-Planck-Institut fur
Gravitationsphysik, Albert-Einstein-Institut, Golm, Germany) | Testing the Cactus code on exact solutions of the Einstein field
equations | 18 pages, 18 figures, Latex | Int.J.Mod.Phys. C13 (2002) 805-822 | 10.1142/S0129183102003577 | null | gr-qc | null | The article presents a series of numerical simulations of exact solutions of
the Einstein equations performed using the Cactus code, a complete
3-dimensional machinery for numerical relativity. We describe an application
(``thorn'') for the Cactus code that can be used for evolving a variety of
exact solutions, with and without matter, including solutions used in modern
cosmology for modeling the early stages of the universe. Our main purpose has
been to test the Cactus code on these well-known examples, focusing mainly on
the stability and convergence of the code.
| [
{
"created": "Fri, 5 Oct 2001 11:19:09 GMT",
"version": "v1"
},
{
"created": "Mon, 4 Mar 2002 11:00:26 GMT",
"version": "v2"
}
] | 2009-11-07 | [
[
"Vulcanov",
"Dumitru N.",
"",
"Max-Planck-Institut fur\n Gravitationsphysik, Albert-Einstein-Institut, Golm, Germany"
],
[
"Alcubierre",
"Miguel",
"",
"Max-Planck-Institut fur\n Gravitationsphysik, Albert-Einstein-Institut, Golm, Germany"
]
] | The article presents a series of numerical simulations of exact solutions of the Einstein equations performed using the Cactus code, a complete 3-dimensional machinery for numerical relativity. We describe an application (``thorn'') for the Cactus code that can be used for evolving a variety of exact solutions, with and without matter, including solutions used in modern cosmology for modeling the early stages of the universe. Our main purpose has been to test the Cactus code on these well-known examples, focusing mainly on the stability and convergence of the code. |
2407.13798 | Swarnim Shashank | Swarnim Shashank, Cosimo Bambi, Rittick Roy | Testing the Kerr nature with binary black hole inspirals | 7 pages, 1 figure. Prepared for the proceeding of the seventh
international workshop on the TianQin science mission | null | null | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The theory of general relativity (GR) is the standard framework for the
description of gravitation and the geometric structure of spacetime. With the
recent advancement of observational instruments, it has become possible to
probe the strong field regime to test GR. We present the constraints obtained
from the binary black hole inspiral data of the LIGO-Virgo-Kagra (LVK)
gravitational wave (GW) observations on the deformations of some popular
parametrized non-Kerr metrics.
| [
{
"created": "Wed, 17 Jul 2024 07:14:44 GMT",
"version": "v1"
}
] | 2024-07-22 | [
[
"Shashank",
"Swarnim",
""
],
[
"Bambi",
"Cosimo",
""
],
[
"Roy",
"Rittick",
""
]
] | The theory of general relativity (GR) is the standard framework for the description of gravitation and the geometric structure of spacetime. With the recent advancement of observational instruments, it has become possible to probe the strong field regime to test GR. We present the constraints obtained from the binary black hole inspiral data of the LIGO-Virgo-Kagra (LVK) gravitational wave (GW) observations on the deformations of some popular parametrized non-Kerr metrics. |
1311.1402 | Santos Jos\'e N\'u\~nez Jare\~no | J.A.R. Cembranos, A.L. Maroto, S.J. N\'u\~nez Jare\~no | Isotropy theorem for arbitrary-spin cosmological fields | 4 pages, 0 figures. Published on JCAP | null | 10.1088/1475-7516/2014/03/042 | null | gr-qc astro-ph.CO hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that the energy-momentum tensor of homogeneous fields of arbitrary
spin in an expanding universe is always isotropic in average provided the
fields remain bounded and evolve rapidly compared to the rate of expansion. An
analytic expression for the average equation of state is obtained for
Lagrangians with generic power-law kinetic and potential terms. As an example
we consider the behavior of a spin-two field in the standard Fierz-Pauli theory
of massive gravity. The results can be extended to general space-time
geometries for locally inertial observers.
| [
{
"created": "Tue, 5 Nov 2013 15:03:00 GMT",
"version": "v1"
},
{
"created": "Fri, 6 Jun 2014 10:00:47 GMT",
"version": "v2"
}
] | 2015-06-17 | [
[
"Cembranos",
"J. A. R.",
""
],
[
"Maroto",
"A. L.",
""
],
[
"Jareño",
"S. J. Núñez",
""
]
] | We show that the energy-momentum tensor of homogeneous fields of arbitrary spin in an expanding universe is always isotropic in average provided the fields remain bounded and evolve rapidly compared to the rate of expansion. An analytic expression for the average equation of state is obtained for Lagrangians with generic power-law kinetic and potential terms. As an example we consider the behavior of a spin-two field in the standard Fierz-Pauli theory of massive gravity. The results can be extended to general space-time geometries for locally inertial observers. |
1802.06808 | Carlos A. S. Almeida | C A S Almeida, D F S Veras and D M Dantas | Corrections to Newton's law of gravitation - application to hybrid Bloch
brane | 7 pages, 3 figures, Proceedings of The XXVth International Conference
on Integrable Systems and Quantum symmetries (ISQS-25) | IOP Conf. Series: Journal of Physics: Conf. Series 965 (2018)
012002 | 10.1088/1742-6596/965/1/012002 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present in this work, the calculations of corrections in the Newton's law
of gravitation due to Kaluza-Klein gravitons in five-dimensional warped thick
braneworld scenarios. We consider here a recently proposed model, namely, the
hybrid Bloch brane. This model couples two scalar fields to gravity and is
engendered from a domain wall-like defect. Also, two other models the so-called
asymmetric hybrid brane and compact brane are considered. As a matter of fact,
these models are obtained from deformations of the phi4 and sine-Gordon
topological defects. Then, we constructed the branes upon such defects, and the
corresponding corrections in Newton's law of gravitation are computed. In order
to attain the mass spectrum and its corresponding eigenfunctions which are the
essential quantities for computing the correction to the Newtonian potential,
we develop a suitable numerical technique.
| [
{
"created": "Mon, 19 Feb 2018 19:03:37 GMT",
"version": "v1"
}
] | 2018-02-21 | [
[
"Almeida",
"C A S",
""
],
[
"Veras",
"D F S",
""
],
[
"Dantas",
"D M",
""
]
] | We present in this work, the calculations of corrections in the Newton's law of gravitation due to Kaluza-Klein gravitons in five-dimensional warped thick braneworld scenarios. We consider here a recently proposed model, namely, the hybrid Bloch brane. This model couples two scalar fields to gravity and is engendered from a domain wall-like defect. Also, two other models the so-called asymmetric hybrid brane and compact brane are considered. As a matter of fact, these models are obtained from deformations of the phi4 and sine-Gordon topological defects. Then, we constructed the branes upon such defects, and the corresponding corrections in Newton's law of gravitation are computed. In order to attain the mass spectrum and its corresponding eigenfunctions which are the essential quantities for computing the correction to the Newtonian potential, we develop a suitable numerical technique. |
2204.00982 | Guangzhou Guo | Guangzhou Guo, Peng Wang, Houwen Wu, and Haitang Yang | Echoes from Hairy Black Holes | 22 pages, 6 figures, 2 tables and references add | null | 10.1007/JHEP06(2022)073 | CTP-SCU/2022004 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the waveforms of time signals produced by scalar perturbations in
static hairy black holes, in which the perturbations can be governed by a
double-peak effective potential. The inner potential peak would give rise to
echoes, which provide a powerful tool to test the Kerr hypothesis. The
waveforms are constructed in the time and frequency domains, and we find that
the late-time waveforms are determined by the long-lived and sub-long-lived
quasinormal modes, which are trapped in the potential valley and near the
smaller peak, respectively. When the distance between the peaks is
significantly larger than the width of the peaks, a train of decaying echo
pulses is produced by the superposition of the long-lived and sub-long-lived
modes. In certain cases, the echoes can vanish and then reappear. When the
peaks are close enough, one detects far fewer echo signals and a following
sinusoid tail, which is controlled by the long-lived or sub-long-lived mode and
hence decays very slowly.
| [
{
"created": "Sun, 3 Apr 2022 04:00:59 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Apr 2022 15:39:30 GMT",
"version": "v2"
}
] | 2022-06-29 | [
[
"Guo",
"Guangzhou",
""
],
[
"Wang",
"Peng",
""
],
[
"Wu",
"Houwen",
""
],
[
"Yang",
"Haitang",
""
]
] | We study the waveforms of time signals produced by scalar perturbations in static hairy black holes, in which the perturbations can be governed by a double-peak effective potential. The inner potential peak would give rise to echoes, which provide a powerful tool to test the Kerr hypothesis. The waveforms are constructed in the time and frequency domains, and we find that the late-time waveforms are determined by the long-lived and sub-long-lived quasinormal modes, which are trapped in the potential valley and near the smaller peak, respectively. When the distance between the peaks is significantly larger than the width of the peaks, a train of decaying echo pulses is produced by the superposition of the long-lived and sub-long-lived modes. In certain cases, the echoes can vanish and then reappear. When the peaks are close enough, one detects far fewer echo signals and a following sinusoid tail, which is controlled by the long-lived or sub-long-lived mode and hence decays very slowly. |
2001.09687 | Andronikos Paliathanasis | Nikolaos Dimakis and Andronikos Paliathanasis | Crossing the phantom divide line as an effect of quantum transitions | 23 pages, 7 figures, version accepted for publication by Classical
and Quantum Gravity | null | 10.1088/1361-6382/abdaf6 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the Chiral cosmological model consisting of two scalar fields
minimally coupled to gravity. In the context of a
Friedmann--Lema\^{\i}tre--Robertson--Walker (FLRW) space-time, and for massless
fields in the presence of a cosmological constant, we present the general
solution of the field equations. The minisuperspace configuration that
possesses maximal symmetry leads to scenarios which - depending on the
admissible value of the parameters - correspond to a quintessence, quintom or
phantom case. The canonical quantization of the model retrieves this
distinction as different families of quantum states. The crossing of the
phantom line is related to the existence of free or bound states for the
Casimir operator of the symmetry algebra of the fields. The classical
singularity, which is present in the quintessence solution, is also resolved at
the quantum level.
| [
{
"created": "Mon, 27 Jan 2020 10:54:39 GMT",
"version": "v1"
},
{
"created": "Mon, 11 Jan 2021 16:25:41 GMT",
"version": "v2"
}
] | 2021-06-09 | [
[
"Dimakis",
"Nikolaos",
""
],
[
"Paliathanasis",
"Andronikos",
""
]
] | We consider the Chiral cosmological model consisting of two scalar fields minimally coupled to gravity. In the context of a Friedmann--Lema\^{\i}tre--Robertson--Walker (FLRW) space-time, and for massless fields in the presence of a cosmological constant, we present the general solution of the field equations. The minisuperspace configuration that possesses maximal symmetry leads to scenarios which - depending on the admissible value of the parameters - correspond to a quintessence, quintom or phantom case. The canonical quantization of the model retrieves this distinction as different families of quantum states. The crossing of the phantom line is related to the existence of free or bound states for the Casimir operator of the symmetry algebra of the fields. The classical singularity, which is present in the quintessence solution, is also resolved at the quantum level. |
1603.08087 | Sang Pyo Kim | Sang Pyo Kim, Won Kim (Kunsan Natl U.) | Will quantum cosmology resurrect chaotic inflation model? | LaTex 10 pages, 1 figure; CosPA 2015 (Cosmology and Particle
Astrophysics), IBS, Daejeon, Korea, Oct. 12-16, 2015; to be published in Int.
J. Mod. Phys.: Conf. Ser | null | 10.1142/S2010194516602052 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The single field chaotic inflation model with a monomial power greater than
one seems to be ruled out by the recent Planck and WMAP CMB data while
Starobinsky model with a higher curvature term seems to be a viable model.
Higher curvature terms being originated from quantum fluctuations, we revisit
the quantum cosmology of the Wheeler-DeWitt equation for the chaotic inflation
model. The semiclassical cosmology emerges from quantum cosmology with
fluctuations of spacetimes and matter when the wave function is peaked around
the semiclassical trajectory with quantum corrections a la the de Broglie-Bohm
pilot theory.
| [
{
"created": "Sat, 26 Mar 2016 08:41:05 GMT",
"version": "v1"
}
] | 2016-08-03 | [
[
"Kim",
"Sang Pyo",
"",
"Kunsan Natl U."
],
[
"Kim",
"Won",
"",
"Kunsan Natl U."
]
] | The single field chaotic inflation model with a monomial power greater than one seems to be ruled out by the recent Planck and WMAP CMB data while Starobinsky model with a higher curvature term seems to be a viable model. Higher curvature terms being originated from quantum fluctuations, we revisit the quantum cosmology of the Wheeler-DeWitt equation for the chaotic inflation model. The semiclassical cosmology emerges from quantum cosmology with fluctuations of spacetimes and matter when the wave function is peaked around the semiclassical trajectory with quantum corrections a la the de Broglie-Bohm pilot theory. |
gr-qc/0504106 | Alessandra Di Credico | Alessandra Di Credico (for the LIGO Scientific Collaboration) | Gravitational wave burst vetoes in the LIGO S2 and S3 data analyses | 9 pages, 4 figures, submitted to Classical and Quantum Gravity for
the special issue of the GWDAW9 Proceedings | Class.Quant.Grav. 22 (2005) S1051-S1058 | 10.1088/0264-9381/22/18/S19 | null | gr-qc | null | The LIGO detectors collected about 4 months of data in 2003-2004 during two
science runs, S2 and S3. Several environmental and auxiliary channels that
monitor the instruments' physical environment and overall interferometric
operation were analyzed in order to establish the quality of the data as well
as the presence of transients of non-astrophysical origin. This analysis
allowed better understanding of the noise character of the instruments and the
establishment of correlations between transients in these channels and the one
recording the gravitational wave strain. In this way vetoes for spurious burst
were identified. We present the methodology we followed in this analysis and
the results from the S2 and S3 veto analysis within the context of the search
for gravitational wave bursts.
| [
{
"created": "Thu, 21 Apr 2005 16:39:21 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Di Credico",
"Alessandra",
"",
"for the LIGO Scientific Collaboration"
]
] | The LIGO detectors collected about 4 months of data in 2003-2004 during two science runs, S2 and S3. Several environmental and auxiliary channels that monitor the instruments' physical environment and overall interferometric operation were analyzed in order to establish the quality of the data as well as the presence of transients of non-astrophysical origin. This analysis allowed better understanding of the noise character of the instruments and the establishment of correlations between transients in these channels and the one recording the gravitational wave strain. In this way vetoes for spurious burst were identified. We present the methodology we followed in this analysis and the results from the S2 and S3 veto analysis within the context of the search for gravitational wave bursts. |
gr-qc/9412008 | David Garfinkle | David Garfinkle | Choptuik scaling in null coordinates | latex (revtex), 6 figures included in the file | Phys.Rev.D51:5558-5561,1995 | 10.1103/PhysRevD.51.5558 | null | gr-qc | null | A numerical simulation is performed of the gravitational collapse of a
spherically symmetric scalar field. The algorithm uses the null initial value
formulation of the Einstein-scalar equations, but does {\it not} use adaptive
mesh refinement. A study is made of the critical phenomena found by Choptuik in
this system. In particular it is verified that the critical solution exhibits
periodic self-similarity. This work thus provides a simple algorithm that gives
verification of the Choptuik results.
| [
{
"created": "Fri, 2 Dec 1994 00:36:48 GMT",
"version": "v1"
}
] | 2010-11-01 | [
[
"Garfinkle",
"David",
""
]
] | A numerical simulation is performed of the gravitational collapse of a spherically symmetric scalar field. The algorithm uses the null initial value formulation of the Einstein-scalar equations, but does {\it not} use adaptive mesh refinement. A study is made of the critical phenomena found by Choptuik in this system. In particular it is verified that the critical solution exhibits periodic self-similarity. This work thus provides a simple algorithm that gives verification of the Choptuik results. |
gr-qc/0612165 | Pankaj S. Joshi | Pankaj S. Joshi | The structure of non-spacelike curves from a spacetime singularity | 4 pages, revtex | null | null | null | gr-qc | null | We investigate here the causal structure of spacetime in the vicinity of a
spacetime singularity. The particle and energy emission from such ultra-dense
regions forming in gravitational collapse of a massive matter cloud is governed
by the nature of non-spacelike paths near the same. These trajectories are
examined to show that if a null geodesic comes out from the singularity, then
there exist families of future-directed non-spacelike curves which also
necessarily escape from the naked singularity. The existence of such families
is crucial to the physical visibility of the singularity. We do not assume any
underlying symmetries for the spacetime, and earlier considerations on the
nature of causal trajectories emerging from a naked singularity are generalized
and clarified.
| [
{
"created": "Tue, 26 Dec 2006 06:39:52 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Joshi",
"Pankaj S.",
""
]
] | We investigate here the causal structure of spacetime in the vicinity of a spacetime singularity. The particle and energy emission from such ultra-dense regions forming in gravitational collapse of a massive matter cloud is governed by the nature of non-spacelike paths near the same. These trajectories are examined to show that if a null geodesic comes out from the singularity, then there exist families of future-directed non-spacelike curves which also necessarily escape from the naked singularity. The existence of such families is crucial to the physical visibility of the singularity. We do not assume any underlying symmetries for the spacetime, and earlier considerations on the nature of causal trajectories emerging from a naked singularity are generalized and clarified. |
1010.5132 | Mihalis Dafermos | Mihalis Dafermos and Igor Rodnianski | Decay for solutions of the wave equation on Kerr exterior spacetimes
I-II: The cases |a| << M or axisymmetry | 57 pages, 4 figures | null | null | null | gr-qc math.AP math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper contains the first two parts (I-II) of a three-part series
concerning the scalar wave equation \Box_g{\psi} = 0 on a fixed Kerr
background. We here restrict to two cases: (II1) |a| \ll M, general {\psi} or
(II2) |a| < M, {\psi} axisymmetric. In either case, we prove a version of
'integrated local energy decay', specifically, that the 4-integral of an
energy-type density (degenerating in a neighborhood of the Schwarzschild photon
sphere and at infinity), integrated over the domain of dependence of a
spacelike hypersurface {\Sigma} connecting the future event horizon with
spacelike infinity or a sphere on null infinity, is bounded by a natural
(non-degenerate) energy flux of {\psi} through {\Sigma}. (The case (II1) has in
fact been treated previously in our Clay Lecture notes: Lectures on black holes
and linear waves, arXiv:0811.0354.) In our forthcoming Part III, the
restriction to axisymmetry for the general |a| < M case is removed. The
complete proof is surveyed in our companion paper The black hole stability
problem for linear scalar perturbations, which includes the essential details
of our forthcoming Part III. Together with previous work (see our: A new
physical-space approach to decay for the wave equation with applications to
black hole spacetimes, in XVIth International Congress on Mathematical Physics,
Pavel Exner ed., Prague 2009 pp. 421-433, 2009, arxiv:0910.4957), this result
leads, under suitable assumptions on initial data of {\psi}, to polynomial
decay bounds for the energy flux of {\psi} through the foliation of the black
hole exterior defined by the time translates of a spacelike hypersurface
{\Sigma} terminating on null infinity, as well as to pointwise decay estimates,
of a definitive form useful for nonlinear applications.
| [
{
"created": "Mon, 25 Oct 2010 14:07:37 GMT",
"version": "v1"
}
] | 2010-10-26 | [
[
"Dafermos",
"Mihalis",
""
],
[
"Rodnianski",
"Igor",
""
]
] | This paper contains the first two parts (I-II) of a three-part series concerning the scalar wave equation \Box_g{\psi} = 0 on a fixed Kerr background. We here restrict to two cases: (II1) |a| \ll M, general {\psi} or (II2) |a| < M, {\psi} axisymmetric. In either case, we prove a version of 'integrated local energy decay', specifically, that the 4-integral of an energy-type density (degenerating in a neighborhood of the Schwarzschild photon sphere and at infinity), integrated over the domain of dependence of a spacelike hypersurface {\Sigma} connecting the future event horizon with spacelike infinity or a sphere on null infinity, is bounded by a natural (non-degenerate) energy flux of {\psi} through {\Sigma}. (The case (II1) has in fact been treated previously in our Clay Lecture notes: Lectures on black holes and linear waves, arXiv:0811.0354.) In our forthcoming Part III, the restriction to axisymmetry for the general |a| < M case is removed. The complete proof is surveyed in our companion paper The black hole stability problem for linear scalar perturbations, which includes the essential details of our forthcoming Part III. Together with previous work (see our: A new physical-space approach to decay for the wave equation with applications to black hole spacetimes, in XVIth International Congress on Mathematical Physics, Pavel Exner ed., Prague 2009 pp. 421-433, 2009, arxiv:0910.4957), this result leads, under suitable assumptions on initial data of {\psi}, to polynomial decay bounds for the energy flux of {\psi} through the foliation of the black hole exterior defined by the time translates of a spacelike hypersurface {\Sigma} terminating on null infinity, as well as to pointwise decay estimates, of a definitive form useful for nonlinear applications. |
2307.03164 | Hassan Firouzjahi | Hassan Firouzjahi, Alireza Talebian | Induced Gravitational Waves from Ultra Slow-Roll Inflation and Pulsar
Timing Arrays Observations | V3: References added, discussions improved, 16 pages, 5 figs. JCAP
published version | null | null | null | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by/4.0/ | The stochastic gravitational wave background (SGWB) detected recently by the
pulsar timing arrays (PTAs) observations may have cosmological origins. In this
work we consider a model of single field inflation containing an intermediate
phase of ultra slow-roll. Fixing the amplitude of the peak of curvature
perturbations by the PBHs bounds we calculate the gravitational waves (GWs)
induced from the curvature perturbations enhanced during USR. The spectrum of
the induced GWs depends on the sharpness of the transition from the USR phase
to the final attractor phase as well as to the duration of the USR period.
While the model can accommodate the current PTAs data but it has non-trivial
predictions for the induced GWs on higher frequency ranges which can be tested
by future observations.
| [
{
"created": "Thu, 6 Jul 2023 17:46:58 GMT",
"version": "v1"
},
{
"created": "Thu, 13 Jul 2023 16:01:59 GMT",
"version": "v2"
},
{
"created": "Sun, 8 Oct 2023 13:04:41 GMT",
"version": "v3"
}
] | 2023-10-10 | [
[
"Firouzjahi",
"Hassan",
""
],
[
"Talebian",
"Alireza",
""
]
] | The stochastic gravitational wave background (SGWB) detected recently by the pulsar timing arrays (PTAs) observations may have cosmological origins. In this work we consider a model of single field inflation containing an intermediate phase of ultra slow-roll. Fixing the amplitude of the peak of curvature perturbations by the PBHs bounds we calculate the gravitational waves (GWs) induced from the curvature perturbations enhanced during USR. The spectrum of the induced GWs depends on the sharpness of the transition from the USR phase to the final attractor phase as well as to the duration of the USR period. While the model can accommodate the current PTAs data but it has non-trivial predictions for the induced GWs on higher frequency ranges which can be tested by future observations. |
gr-qc/0307002 | Hirotaka Takahashi | Hirotaka Takahashi, Hideyuki Tagoshi, the TAMA Collaboration and the
LISM Collaboration | Coincidence analysis to search for inspiraling compact binaries | 14 pages, 3 figures,accepted for publication in Class. Quant. Grav.
as Special issue article (Proceedings of GWDAW December 17-19, 2002, Kyoto,
Japan) | Class.Quant.Grav. 20 (2003) S741-S751 | 10.1088/0264-9381/20/17/317 | null | gr-qc astro-ph | null | We discuss a method of coincidence analysis to search for gravitational waves
from inspiraling compact binaries using the data of two laser interferometer
gravitational wave detectors. We examine the allowed difference of the wave's
parameters estimated by each detector to obtain good detection efficiency. We
also discuss a method to set an upper limit to the event rate from the results
of the coincidence analysis. For the purpose to test above methods, we
performed a coincidence analysis by applying these methods to the real data of
TAMA300 and LISM detectors taken during 2001. We show that the fake event rate
is reduced significantly by the coincidence analysis without losing real events
very much. Results of the test analysis are also given.
| [
{
"created": "Tue, 1 Jul 2003 04:16:09 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Takahashi",
"Hirotaka",
""
],
[
"Tagoshi",
"Hideyuki",
""
],
[
"Collaboration",
"the TAMA",
""
],
[
"Collaboration",
"the LISM",
""
]
] | We discuss a method of coincidence analysis to search for gravitational waves from inspiraling compact binaries using the data of two laser interferometer gravitational wave detectors. We examine the allowed difference of the wave's parameters estimated by each detector to obtain good detection efficiency. We also discuss a method to set an upper limit to the event rate from the results of the coincidence analysis. For the purpose to test above methods, we performed a coincidence analysis by applying these methods to the real data of TAMA300 and LISM detectors taken during 2001. We show that the fake event rate is reduced significantly by the coincidence analysis without losing real events very much. Results of the test analysis are also given. |
1312.4641 | Sergey Kozyrev | Sergey Kozyrev | From Brans-Dicke theory to Newtonian gravity | 4 pages | null | null | null | gr-qc | http://creativecommons.org/licenses/publicdomain/ | We present the new interpretation of scalar field for the Brans-Dicke theory.
This interpretation is obtained by considering a fixed spacetime structure of
manifold.
| [
{
"created": "Tue, 17 Dec 2013 05:06:37 GMT",
"version": "v1"
},
{
"created": "Sun, 22 Dec 2013 05:37:46 GMT",
"version": "v2"
}
] | 2013-12-24 | [
[
"Kozyrev",
"Sergey",
""
]
] | We present the new interpretation of scalar field for the Brans-Dicke theory. This interpretation is obtained by considering a fixed spacetime structure of manifold. |
1602.07992 | Sam Dolan Dr | David Dempsey and Sam R Dolan | Waves and null congruences in a draining bathtub | 12 pages, 2 figures. Proceedings for III Amazonian Symposium on
Physics | Int.J.Mod.Phys.D 25 (2016) 1641004 | 10.1142/S0218271816410042 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study wave propagation in a draining bathtub: a fluid-mechanical black
hole analogue in which perturbations are governed by a Klein-Gordon equation on
an effective Lorentzian geometry. Like the Kerr spacetime, the draining bathtub
geometry possesses an (effective) horizon, an ergosphere and null circular
orbits. We propose that a `pulse' disturbance may be used to map out the
light-cone of the effective geometry. First, we apply the eikonal approximation
to elucidate the link between wavefronts, null geodesic congruences and the
Raychaudhuri equation. Next, we solve the wave equation numerically in the time
domain using the method of lines. Starting with Gaussian initial data, we
demonstrate that a pulse will propagate along a null congruence and thus trace
out the light-cone of the effective geometry. Our numerical results reveal
features, such as wavefront intersections, frame-dragging, winding and
interference effects, that are closely associated with the presence of null
circular orbits and the ergosphere.
| [
{
"created": "Thu, 25 Feb 2016 16:47:37 GMT",
"version": "v1"
}
] | 2016-05-11 | [
[
"Dempsey",
"David",
""
],
[
"Dolan",
"Sam R",
""
]
] | We study wave propagation in a draining bathtub: a fluid-mechanical black hole analogue in which perturbations are governed by a Klein-Gordon equation on an effective Lorentzian geometry. Like the Kerr spacetime, the draining bathtub geometry possesses an (effective) horizon, an ergosphere and null circular orbits. We propose that a `pulse' disturbance may be used to map out the light-cone of the effective geometry. First, we apply the eikonal approximation to elucidate the link between wavefronts, null geodesic congruences and the Raychaudhuri equation. Next, we solve the wave equation numerically in the time domain using the method of lines. Starting with Gaussian initial data, we demonstrate that a pulse will propagate along a null congruence and thus trace out the light-cone of the effective geometry. Our numerical results reveal features, such as wavefront intersections, frame-dragging, winding and interference effects, that are closely associated with the presence of null circular orbits and the ergosphere. |
2011.14633 | Olivier Minazzoli | Olivier Minazzoli | De Sitter space-times in Entangled Relativity | 9 pages, no figure | Class. Quantum Grav.38(2021) 137003 (7pp) | 10.1088/1361-6382/ac0589 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is argued that de Sitter space-times might be solutions of entangled
relativity once the quantum trace anomaly from matter fields in curved
space-times is taken into account. This hypothesis would be an elegant solution
to the acceleration of the expansion of the universe within the rigid framework
of entangled relativity.
| [
{
"created": "Mon, 30 Nov 2020 09:18:29 GMT",
"version": "v1"
},
{
"created": "Thu, 6 May 2021 08:05:05 GMT",
"version": "v2"
}
] | 2021-06-25 | [
[
"Minazzoli",
"Olivier",
""
]
] | It is argued that de Sitter space-times might be solutions of entangled relativity once the quantum trace anomaly from matter fields in curved space-times is taken into account. This hypothesis would be an elegant solution to the acceleration of the expansion of the universe within the rigid framework of entangled relativity. |
1402.4521 | Shohei Aoyama | Shohei Aoyama, Rina Tazai, Kiyotomo Ichiki | Upper limit on the amplitude of gravitational waves around 0.1Hz from
the Global Positioning System | 6 pages, 2figures, Accepted for the publication in Physical Review D | null | 10.1103/PhysRevD.89.067101 | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The global positioning system (GPS) is composed of thirty one satellites
having atomic clocks with $10^{-15}$ accuracy on board and enables one to
calibrate the primary standard for frequency on the ground. Using the fact that
oscillators on the ground have been successfully stabilized with high accuracy
by receiving radio waves emitted from the GPS satellites, we set a constraint
on the strain amplitude of the gravitational wave background $h_{\rm c}$. We
find that the GPS has already placed a meaningful constraint, and the
constraint on the continuous component of gravitational waves is given as
$h_{\rm c}<4.8\times 10^{-12}(1/ f)$ at $10^{-2}\lesssim f \lesssim 10^{0}$ Hz,
for stabilized oscillators with ${\Delta \nu}/{\nu}\simeq 10^{-12}$. Thanks to
the advantage of the Doppler tracking method, seismic oscillations do not
affect the current constraint. Constraints on $h_c$ in the same frequency range
from the velocity measurements by the lunar explorers in the Apollo mission are
also derived.
| [
{
"created": "Tue, 18 Feb 2014 22:50:29 GMT",
"version": "v1"
}
] | 2015-06-18 | [
[
"Aoyama",
"Shohei",
""
],
[
"Tazai",
"Rina",
""
],
[
"Ichiki",
"Kiyotomo",
""
]
] | The global positioning system (GPS) is composed of thirty one satellites having atomic clocks with $10^{-15}$ accuracy on board and enables one to calibrate the primary standard for frequency on the ground. Using the fact that oscillators on the ground have been successfully stabilized with high accuracy by receiving radio waves emitted from the GPS satellites, we set a constraint on the strain amplitude of the gravitational wave background $h_{\rm c}$. We find that the GPS has already placed a meaningful constraint, and the constraint on the continuous component of gravitational waves is given as $h_{\rm c}<4.8\times 10^{-12}(1/ f)$ at $10^{-2}\lesssim f \lesssim 10^{0}$ Hz, for stabilized oscillators with ${\Delta \nu}/{\nu}\simeq 10^{-12}$. Thanks to the advantage of the Doppler tracking method, seismic oscillations do not affect the current constraint. Constraints on $h_c$ in the same frequency range from the velocity measurements by the lunar explorers in the Apollo mission are also derived. |
2207.05594 | Arun Mangalam | Prerna Rana (1), A. Mangalam (2) ((1) Tata Institute of Fundamental
Research, (2) Indian Institute of Astrophysics) | Bound orbit domains in the phase space of the Kerr geometry | 7 pages, 2 figures, Conference: Proceedings of the MG15 Meeting on
General Relativity | null | 10.1142/9789811258251_0116 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive the conditions for a non-equatorial eccentric bound orbit to exist
around a Kerr black hole in two-parameter spaces: the energy, angular momentum
of the test particle, spin of the black hole, and Carter's constant space ($E$,
$L$, $a$, $Q$), and eccentricity, inverse-latus rectum space ($e$, $\mu$, $a$,
$Q$). These conditions distribute various kinds of bound orbits in different
regions of the ($E$, $L$) and ($e$, $\mu$) planes, depending on which pair of
roots of the effective potential forms a bound orbit. We provide a prescription
to select these parameters for bound orbits, which are useful inputs to study
bound trajectory evolution in various astrophysical applications like
simulations of gravitational wave emission from extreme-mass ratio inspirals,
relativistic precession around black holes, and the study of gyroscope
precession as a test of general relativity.
| [
{
"created": "Tue, 12 Jul 2022 15:12:42 GMT",
"version": "v1"
}
] | 2022-12-07 | [
[
"Rana",
"Prerna",
""
],
[
"Mangalam",
"A.",
""
]
] | We derive the conditions for a non-equatorial eccentric bound orbit to exist around a Kerr black hole in two-parameter spaces: the energy, angular momentum of the test particle, spin of the black hole, and Carter's constant space ($E$, $L$, $a$, $Q$), and eccentricity, inverse-latus rectum space ($e$, $\mu$, $a$, $Q$). These conditions distribute various kinds of bound orbits in different regions of the ($E$, $L$) and ($e$, $\mu$) planes, depending on which pair of roots of the effective potential forms a bound orbit. We provide a prescription to select these parameters for bound orbits, which are useful inputs to study bound trajectory evolution in various astrophysical applications like simulations of gravitational wave emission from extreme-mass ratio inspirals, relativistic precession around black holes, and the study of gyroscope precession as a test of general relativity. |
2205.05149 | Vitorio A. De Lorenci | V. A. De Lorenci and L. T. de Paula | Analog models for gravity in linear magnetoelectrics | 7 pages, 1 figure | null | null | null | gr-qc physics.optics | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Formal analogies between gravitational and optical phenomena have been
subject of study for over a century, leading to interesting scenarios for
testing kinematic aspects of general relativity in terrestrial laboratories.
Here, some aspects about analog models for gravity obtained from the analysis
of light propagation in linear magnetoeletric media are examined. In
particular, it is shown that this effect produces mixed time-space terms in the
effective metric that depend only on the antisymmetric part of the generally
non-symmetric magnetoelectric coefficient. Furthermore, it is shown that
solutions presenting analog event horizons can be proposed in this scenario,
provided that certain consistency conditions are satisfied. A short discussion
comparing different ways of constructing analog models is also presented.
| [
{
"created": "Tue, 10 May 2022 20:06:50 GMT",
"version": "v1"
}
] | 2022-05-12 | [
[
"De Lorenci",
"V. A.",
""
],
[
"de Paula",
"L. T.",
""
]
] | Formal analogies between gravitational and optical phenomena have been subject of study for over a century, leading to interesting scenarios for testing kinematic aspects of general relativity in terrestrial laboratories. Here, some aspects about analog models for gravity obtained from the analysis of light propagation in linear magnetoeletric media are examined. In particular, it is shown that this effect produces mixed time-space terms in the effective metric that depend only on the antisymmetric part of the generally non-symmetric magnetoelectric coefficient. Furthermore, it is shown that solutions presenting analog event horizons can be proposed in this scenario, provided that certain consistency conditions are satisfied. A short discussion comparing different ways of constructing analog models is also presented. |
0812.2843 | Joel Weller | Philippe Brax, Carsten van de Bruck, Lisa M. H. Hall and Joel M.
Weller | Slow-Roll Inflation in the Presence of a Dark Energy Coupling | 15 pages, 7 figures; added references and a more detailed treatment
of the perturbation equations (Sec. II.B and fig.1) | Phys.Rev.D79:103508,2009 | 10.1103/PhysRevD.79.103508 | null | gr-qc astro-ph hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In models of coupled dark energy, in which a dark energy scalar field couples
to other matter components, it is natural to expect a coupling to the inflaton
as well. We explore the consequences of such a coupling in the context of
single field slow-roll inflation. Assuming an exponential potential for the
quintessence field we show that the coupling to the inflaton causes the
quintessence field to be attracted towards the minimum of the effective
potential. If the coupling is large enough, the field is heavy and is located
at the minimum. We show how this affects the expansion rate and the slow-roll
of the inflaton field, and therefore the primordial perturbations generated
during inflation. We further show that the coupling has an important impact on
the processes of reheating and preheating.
| [
{
"created": "Mon, 15 Dec 2008 16:34:31 GMT",
"version": "v1"
},
{
"created": "Mon, 18 May 2009 15:28:06 GMT",
"version": "v2"
}
] | 2009-10-29 | [
[
"Brax",
"Philippe",
""
],
[
"van de Bruck",
"Carsten",
""
],
[
"Hall",
"Lisa M. H.",
""
],
[
"Weller",
"Joel M.",
""
]
] | In models of coupled dark energy, in which a dark energy scalar field couples to other matter components, it is natural to expect a coupling to the inflaton as well. We explore the consequences of such a coupling in the context of single field slow-roll inflation. Assuming an exponential potential for the quintessence field we show that the coupling to the inflaton causes the quintessence field to be attracted towards the minimum of the effective potential. If the coupling is large enough, the field is heavy and is located at the minimum. We show how this affects the expansion rate and the slow-roll of the inflaton field, and therefore the primordial perturbations generated during inflation. We further show that the coupling has an important impact on the processes of reheating and preheating. |
1003.4246 | Claus Gerhardt | Claus Gerhardt | Combining gravity with the forces of the standard model on a
cosmological scale | 53 pages, v6: some typos corrected | Class.Quant.Grav.27:155008,2010 | 10.1088/0264-9381/27/15/155008 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We prove the existence of a spectral resolution of the Wheeler-DeWitt
equation when the underlying spacetime is a Friedman universe with flat spatial
slices and where the matter fields are comprised of the strong interaction,
with $\SU(3)$ replaced by a general $\SU(n)$, $n\ge 2$, and the electro-weak
interaction. The wave functions are maps from $\R[4n+10]$ to a subspace of the
antisymmetric Fock space, and one noteworthy result is that, whenever the
electro-weak interaction is involved, the image of an eigenfunction is in
general not one dimensional, i.e., in general it makes no sense specifying a
fermion and looking for an eigenfunction the range of which is contained in the
one dimensional vector space spanned by the fermion.
| [
{
"created": "Mon, 22 Mar 2010 19:17:47 GMT",
"version": "v1"
},
{
"created": "Mon, 29 Mar 2010 12:01:15 GMT",
"version": "v2"
},
{
"created": "Tue, 6 Apr 2010 15:45:11 GMT",
"version": "v3"
},
{
"created": "Fri, 7 May 2010 18:44:24 GMT",
"version": "v4"
},
{
"cre... | 2010-07-27 | [
[
"Gerhardt",
"Claus",
""
]
] | We prove the existence of a spectral resolution of the Wheeler-DeWitt equation when the underlying spacetime is a Friedman universe with flat spatial slices and where the matter fields are comprised of the strong interaction, with $\SU(3)$ replaced by a general $\SU(n)$, $n\ge 2$, and the electro-weak interaction. The wave functions are maps from $\R[4n+10]$ to a subspace of the antisymmetric Fock space, and one noteworthy result is that, whenever the electro-weak interaction is involved, the image of an eigenfunction is in general not one dimensional, i.e., in general it makes no sense specifying a fermion and looking for an eigenfunction the range of which is contained in the one dimensional vector space spanned by the fermion. |
1309.5971 | Jose' P. S. Lemos | Jos\'e P. S. Lemos, Paulo Pani | Gravitational fields with sources, regular black holes, quasiblack
holes, and analogue black holes | Report of the Parallel Session AT3 at the Marcel Grossmann Meeting
13, Stockholm 2012, Proceedings of the Conference. 9 pages | null | null | null | gr-qc astro-ph.SR hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss recent developments in gravitational fields with sources, regular
black holes, quasiblack holes, and analogue black holes, related to the talks
presented at the corresponding Parallel Session AT3 of the 13th Marcel
Grossmann Meeting.
| [
{
"created": "Mon, 23 Sep 2013 20:21:53 GMT",
"version": "v1"
}
] | 2013-09-25 | [
[
"Lemos",
"José P. S.",
""
],
[
"Pani",
"Paulo",
""
]
] | We discuss recent developments in gravitational fields with sources, regular black holes, quasiblack holes, and analogue black holes, related to the talks presented at the corresponding Parallel Session AT3 of the 13th Marcel Grossmann Meeting. |
gr-qc/9412017 | Pietro Menotti | Pietro Menotti | Gravity in 2+1 dimensions | Two lectures given at the XI Italian Relativity Meeting, Trieste
26-30 September 1994 ; 30 pages plain TeX, no figures | null | null | IFUP-TH-70/94 | gr-qc hep-th | null | A review is given of some classical and quantum aspects of 2+1 dimensional
gravity.
| [
{
"created": "Tue, 6 Dec 1994 09:36:00 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Menotti",
"Pietro",
""
]
] | A review is given of some classical and quantum aspects of 2+1 dimensional gravity. |
1011.2726 | Razvan-Gheorghe Gurau | Razvan Gurau | The 1/N expansion of colored tensor models | typos corrected, references updated | Annales Henri Poincare 12:829-847,2011 | 10.1007/s00023-011-0101-8 | PI-QG-201 | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we perform the 1/N expansion of the colored three dimensional
Boulatov tensor model. As in matrix models, we obtain a systematic topological
expansion, with more and more complicated topologies suppressed by higher and
higher powers of N. We compute the first orders of the expansion and prove that
only graphs corresponding to three spheres S^3 contribute to the leading order
in the large N limit.
| [
{
"created": "Thu, 11 Nov 2010 18:07:42 GMT",
"version": "v1"
},
{
"created": "Wed, 17 Nov 2010 15:46:17 GMT",
"version": "v2"
}
] | 2011-05-18 | [
[
"Gurau",
"Razvan",
""
]
] | In this paper we perform the 1/N expansion of the colored three dimensional Boulatov tensor model. As in matrix models, we obtain a systematic topological expansion, with more and more complicated topologies suppressed by higher and higher powers of N. We compute the first orders of the expansion and prove that only graphs corresponding to three spheres S^3 contribute to the leading order in the large N limit. |
gr-qc/9801049 | Tomohiro Harada | Tomohiro Harada | Neutron stars in scalar-tensor theories of gravity and catastrophe
theory | 17 pages, 9 postscript figures. Accepted for publication in Physical
Review D | Phys.Rev. D57 (1998) 4802-4811 | 10.1103/PhysRevD.57.4802 | KUNS-1476 | gr-qc astro-ph | null | We investigate neutron stars in scalar-tensor theories. We examine their
secular stability against spherically symmetric perturbations by use of a
turning point method. For some choices of the coupling function contained in
the theories, the number of the stable equilibrium solutions changes and the
realized equilibrium may change discontinuously as the asymptotic value of the
scalar field or total baryon number is changed continuously. The behaviour of
the stable equilibrium solutions is explained by fold and cusp catastrophes.
Whether the cusp catastrophe appears or not depends on the choices of the
coupling function. These types of the catastrophes are structurally stable.
Recently discovered spontaneous scalarization, which is non-perturbative
strong-field phenomenon due to the presence of the gravitational scalar field,
is well described in terms of the cusp catastrophe.
| [
{
"created": "Wed, 14 Jan 1998 14:10:15 GMT",
"version": "v1"
},
{
"created": "Tue, 24 Feb 1998 02:04:04 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Harada",
"Tomohiro",
""
]
] | We investigate neutron stars in scalar-tensor theories. We examine their secular stability against spherically symmetric perturbations by use of a turning point method. For some choices of the coupling function contained in the theories, the number of the stable equilibrium solutions changes and the realized equilibrium may change discontinuously as the asymptotic value of the scalar field or total baryon number is changed continuously. The behaviour of the stable equilibrium solutions is explained by fold and cusp catastrophes. Whether the cusp catastrophe appears or not depends on the choices of the coupling function. These types of the catastrophes are structurally stable. Recently discovered spontaneous scalarization, which is non-perturbative strong-field phenomenon due to the presence of the gravitational scalar field, is well described in terms of the cusp catastrophe. |
2107.12164 | Bibhas Majhi Ranjan | Mousumi Maitra, Debaprasad Maity, Bibhas Ranjan Majhi | BMS Goldstone modes near the horizon of a Kerr black hole are thermal | Minor modifications, to appear Phys. Lett. B | null | 10.1016/j.physletb.2021.136825 | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Near horizon Bondi-Metzner-Sachs (BMS) like symmetry is spontaneously broken
by the black hole background itself and hence gives rise to Goldstone mode. The
associated Goldstone mode for the near horizon BMS like symmetry of a
Schwarzschild black hole was found to behave like inverted harmonic
oscillators, which has been further shown to lead to thermodynamic temperature
in the semi-classical regime. Here we investigate the generalization of this
previous findings for the Kerr black hole. The analysis is being performed for
two different situations. Firstly, we analyze Goldstone mode dynamics
considering {\it slowly rotating} Kerr. In other case the problem is solved in
the frame of {\it zero angular momentum observer} (ZAMO) with arbitrary value
of rotation. In both analysis the effective semi-classical temperature of
Goldstone modes turn out to be proportional to that of Hawking temperature. Due
to such similarity and generality we feel that these Goldstone modes may play
important role to understand the underlying microscopic description of horizon
thermalization.
| [
{
"created": "Mon, 26 Jul 2021 12:31:24 GMT",
"version": "v1"
},
{
"created": "Fri, 10 Dec 2021 06:31:50 GMT",
"version": "v2"
}
] | 2021-12-15 | [
[
"Maitra",
"Mousumi",
""
],
[
"Maity",
"Debaprasad",
""
],
[
"Majhi",
"Bibhas Ranjan",
""
]
] | Near horizon Bondi-Metzner-Sachs (BMS) like symmetry is spontaneously broken by the black hole background itself and hence gives rise to Goldstone mode. The associated Goldstone mode for the near horizon BMS like symmetry of a Schwarzschild black hole was found to behave like inverted harmonic oscillators, which has been further shown to lead to thermodynamic temperature in the semi-classical regime. Here we investigate the generalization of this previous findings for the Kerr black hole. The analysis is being performed for two different situations. Firstly, we analyze Goldstone mode dynamics considering {\it slowly rotating} Kerr. In other case the problem is solved in the frame of {\it zero angular momentum observer} (ZAMO) with arbitrary value of rotation. In both analysis the effective semi-classical temperature of Goldstone modes turn out to be proportional to that of Hawking temperature. Due to such similarity and generality we feel that these Goldstone modes may play important role to understand the underlying microscopic description of horizon thermalization. |
1704.04169 | Daiske Yoshida | Daiske Yoshida, Jiro Soda | Electromagnetic Memory Effect Induced by Axion Dark Matter | 11 pages, 2 figures | Phys. Rev. D 96, 064005 (2017) | 10.1103/PhysRevD.96.064005 | KOBE-COSMO-17-06 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Memory effects of gravitational waves from astronomical events or primordial
universe might have the information of new physics. It is intriguing to observe
that the memory effect exists in electrodynamics as a net momentum kick, while
the memory effect in gravity appears as a net relatively displacement. In
particular, Winicour has shown that the B-mode memory, which characterizes
parity odd global distribution of memory, does not exist. We study the memory
effect in axion electrodynamics and find that the B-mode memory effect can
exist provided the existence of coherently oscillating axion background field.
Moreover, we examine the detectability of the axion dark matter using this
effect. We also argue the existence of the B-mode gravitational memory effect
in the presence of the axion dark matter.
| [
{
"created": "Thu, 13 Apr 2017 15:14:17 GMT",
"version": "v1"
},
{
"created": "Fri, 8 Sep 2017 06:47:51 GMT",
"version": "v2"
}
] | 2017-09-13 | [
[
"Yoshida",
"Daiske",
""
],
[
"Soda",
"Jiro",
""
]
] | Memory effects of gravitational waves from astronomical events or primordial universe might have the information of new physics. It is intriguing to observe that the memory effect exists in electrodynamics as a net momentum kick, while the memory effect in gravity appears as a net relatively displacement. In particular, Winicour has shown that the B-mode memory, which characterizes parity odd global distribution of memory, does not exist. We study the memory effect in axion electrodynamics and find that the B-mode memory effect can exist provided the existence of coherently oscillating axion background field. Moreover, we examine the detectability of the axion dark matter using this effect. We also argue the existence of the B-mode gravitational memory effect in the presence of the axion dark matter. |
0901.1387 | Bijan Saha | Bijan Saha | Spinor model of a perfect fluid | 5 pages, some misprints are corrected, some new expressions are added | Central Eur.J.Phys.8 (2010) 920 - 923 | 10.2478/s11534-010-0019-7 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Different characteristic of matter influencing the evolution of the Universe
has been simulated by means of a nonlinear spinor field. We have considered two
cases where the spinor field nonlinearity occurs either as a result of
self-action or due to the interaction with a scalar field.
| [
{
"created": "Sat, 10 Jan 2009 16:44:53 GMT",
"version": "v1"
},
{
"created": "Thu, 29 Jan 2009 08:49:03 GMT",
"version": "v2"
}
] | 2015-05-01 | [
[
"Saha",
"Bijan",
""
]
] | Different characteristic of matter influencing the evolution of the Universe has been simulated by means of a nonlinear spinor field. We have considered two cases where the spinor field nonlinearity occurs either as a result of self-action or due to the interaction with a scalar field. |
2304.04198 | Yan Peng | Guohua Liu, Yan Peng | No long hair behaviors of ultra-compact objects | 7 pages | null | null | null | gr-qc hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate distributions of matter fields outside spherically symmetric
ultra-compact objects in the asymptotically flat background. Based on the
dominant energy condition and the non-negative trace condition, we analytically
find a no long hair behavior, which states that the effective radius of matter
field hairs cannot extend beyond the outermost null circular orbit.
| [
{
"created": "Sun, 9 Apr 2023 09:07:16 GMT",
"version": "v1"
}
] | 2023-04-11 | [
[
"Liu",
"Guohua",
""
],
[
"Peng",
"Yan",
""
]
] | We investigate distributions of matter fields outside spherically symmetric ultra-compact objects in the asymptotically flat background. Based on the dominant energy condition and the non-negative trace condition, we analytically find a no long hair behavior, which states that the effective radius of matter field hairs cannot extend beyond the outermost null circular orbit. |
2302.10155 | Miguel Cruz | V\'ictor H. C\'ardenas, Miguel Cruz and Samuel Lepe | Generalized second law of thermodynamics for the matter creation
scenario and emergence of phantom regime | 7 pages, no figures. Accepted for publication in EPJ Plus | Eur. Phys. J. Plus 139, 642 (2024) | 10.1140/epjp/s13360-024-05447-x | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This work is focused on the exploration of the thermodynamics foundations of
the matter creation scenario when a generalized form of the second law of
thermodynamics for this scheme is implemented. In this scenario we consider an
expanding cosmology in which the created matter is trapped by the apparent
horizon. The scheme leads to phantom evolution but at first glance it lacks of
physical consistency. However, the inclusion of chemical potential into the
description solves the thermodynamics issues of the model and determines the
behavior of the cosmic fluid, in other words, the cosmic fluid now can behave
as phantom dark energy or as quintessence one.
| [
{
"created": "Mon, 20 Feb 2023 18:40:55 GMT",
"version": "v1"
},
{
"created": "Wed, 9 Aug 2023 19:29:47 GMT",
"version": "v2"
},
{
"created": "Wed, 22 Nov 2023 22:46:32 GMT",
"version": "v3"
},
{
"created": "Sun, 21 Jul 2024 16:46:01 GMT",
"version": "v4"
}
] | 2024-07-23 | [
[
"Cárdenas",
"Víctor H.",
""
],
[
"Cruz",
"Miguel",
""
],
[
"Lepe",
"Samuel",
""
]
] | This work is focused on the exploration of the thermodynamics foundations of the matter creation scenario when a generalized form of the second law of thermodynamics for this scheme is implemented. In this scenario we consider an expanding cosmology in which the created matter is trapped by the apparent horizon. The scheme leads to phantom evolution but at first glance it lacks of physical consistency. However, the inclusion of chemical potential into the description solves the thermodynamics issues of the model and determines the behavior of the cosmic fluid, in other words, the cosmic fluid now can behave as phantom dark energy or as quintessence one. |
0708.2490 | Rickard Jonsson | Rickard Jonsson | Gyroscope precession in special and general relativity from basic
principles | 10 pages, 14 figures. Also includes an addendum, 1 page, 1 figure | Am.J.Phys.75:463-471,2007 | 10.1119/1.2719202 | null | gr-qc | null | In special relativity a gyroscope that is suspended in a torque-free manner
will precess as it is moved along a curved path relative to an inertial frame
S. We explain this effect, which is known as Thomas precession, by considering
a real grid that moves along with the gyroscope, and that by definition is not
rotating as observed from its own momentary inertial rest frame. From the basic
properties of the Lorentz transformation we deduce how the form and rotation of
the grid (and hence the gyroscope) will evolve relative to S. As an
intermediate step we consider how the grid would appear if it were not length
contracted along the direction of motion. We show that the uncontracted grid
obeys a simple law of rotation. This law simplifies the analysis of spin
precession compared to more traditional approaches based on Fermi transport. We
also consider gyroscope precession relative to an accelerated reference frame
and show that there are extra precession effects that can be explained in a way
analogous to the Thomas precession. Although fully relativistically correct,
the entire analysis is carried out using three-vectors. By using the
equivalence principle the formalism can also be applied to static spacetimes in
general relativity. As an example, we calculate the precession of a gyroscope
orbiting a static black hole. In an addendum the general reasoning is extended
to include also rotating reference frames.
| [
{
"created": "Sat, 18 Aug 2007 15:17:58 GMT",
"version": "v1"
}
] | 2010-11-11 | [
[
"Jonsson",
"Rickard",
""
]
] | In special relativity a gyroscope that is suspended in a torque-free manner will precess as it is moved along a curved path relative to an inertial frame S. We explain this effect, which is known as Thomas precession, by considering a real grid that moves along with the gyroscope, and that by definition is not rotating as observed from its own momentary inertial rest frame. From the basic properties of the Lorentz transformation we deduce how the form and rotation of the grid (and hence the gyroscope) will evolve relative to S. As an intermediate step we consider how the grid would appear if it were not length contracted along the direction of motion. We show that the uncontracted grid obeys a simple law of rotation. This law simplifies the analysis of spin precession compared to more traditional approaches based on Fermi transport. We also consider gyroscope precession relative to an accelerated reference frame and show that there are extra precession effects that can be explained in a way analogous to the Thomas precession. Although fully relativistically correct, the entire analysis is carried out using three-vectors. By using the equivalence principle the formalism can also be applied to static spacetimes in general relativity. As an example, we calculate the precession of a gyroscope orbiting a static black hole. In an addendum the general reasoning is extended to include also rotating reference frames. |
1508.01102 | Hristu Culetu | Hristu Culetu | Screening an extremal black hole with a thin shell of exotic matter | 7 pages, no figures, minor changes, published in Physics of the Dark
Universe 14 (2016) 1-3 | null | 10.1016/j.dark.2016.07.004 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the possibility of shielding a regular extremal black hole by means
of a matter thin-shell. While the surface energy density $\sigma$ on the static
shell is negative, the tangential pressures $p$ are positive, both of them
being finite when the shell approaches the black hole horizon. The
Darmois-Israel junction conditions are used to find $\sigma$ and $p$ in terms
of the radius $a$ of the shell. The surface gravitational energy $E_{S}$ is
computed, keeping track of the pressure contribution. The stability conditions
are briefly investigated.
| [
{
"created": "Wed, 5 Aug 2015 15:17:13 GMT",
"version": "v1"
},
{
"created": "Sun, 9 Aug 2015 10:29:32 GMT",
"version": "v2"
},
{
"created": "Thu, 8 Oct 2015 13:44:44 GMT",
"version": "v3"
},
{
"created": "Fri, 12 Aug 2016 15:42:59 GMT",
"version": "v4"
}
] | 2016-08-15 | [
[
"Culetu",
"Hristu",
""
]
] | We study the possibility of shielding a regular extremal black hole by means of a matter thin-shell. While the surface energy density $\sigma$ on the static shell is negative, the tangential pressures $p$ are positive, both of them being finite when the shell approaches the black hole horizon. The Darmois-Israel junction conditions are used to find $\sigma$ and $p$ in terms of the radius $a$ of the shell. The surface gravitational energy $E_{S}$ is computed, keeping track of the pressure contribution. The stability conditions are briefly investigated. |
0801.2213 | Matveev Alexei S. | V.E. Didenko, A.S. Matveev and M.A. Vasiliev | Unfolded Description of $AdS_4$ Kerr Black Hole | 18 pages | Phys.Lett.B665:284-293,2008 | 10.1016/j.physletb.2008.05.067 | null | gr-qc hep-th | null | It is shown that $AdS_4$ Kerr black hole is a solution of simple unfolded
differential equations that form a deformation of the zero-curvature
description of empty $AdS_4$ space-time. Our construction uses the Killing
symmetries of the Kerr solution. All known and some new algebraic properties of
the Kerr-Schild solution result from the obtained black hole unfolded system in
the coordinate-independent way. Kerr Schild type solutions of free equations in
$AdS_4$ for massless fields of any spin, associated to the proposed black hole
unfolded system, are found.
| [
{
"created": "Tue, 15 Jan 2008 05:01:34 GMT",
"version": "v1"
},
{
"created": "Wed, 16 Jan 2008 00:20:39 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Didenko",
"V. E.",
""
],
[
"Matveev",
"A. S.",
""
],
[
"Vasiliev",
"M. A.",
""
]
] | It is shown that $AdS_4$ Kerr black hole is a solution of simple unfolded differential equations that form a deformation of the zero-curvature description of empty $AdS_4$ space-time. Our construction uses the Killing symmetries of the Kerr solution. All known and some new algebraic properties of the Kerr-Schild solution result from the obtained black hole unfolded system in the coordinate-independent way. Kerr Schild type solutions of free equations in $AdS_4$ for massless fields of any spin, associated to the proposed black hole unfolded system, are found. |
gr-qc/0009048 | Semyon Pol'shin | Simeon Pol'shin | Quantization of massless fields over the static Robertson-Walker space
of constant negative curvature | 13 pages, LATEX, using ioplppt.sty and iopfts.sty. v.2: discussion
with a lot of references is added. To appear in CQG | Class.Quant.Grav. 18 (2001) 2905-2916 | 10.1088/0264-9381/18/15/306 | null | gr-qc | null | Taking the ${\Bbb R}^1 \times H^3$ space as an example, we develop the new
method of quantization of fields over symmetric spaces. We construct the
quantized massless fields of an arbitrary spin over the ${\Bbb R}^1 \times H^3$
space by the resolution over the systems of "plane waves" which are solutions
of the corresponding wave equations. The propagators of these fields are ${\Bbb
R}^1 \times SO(3,1)$-invariant and causal. For spin 0 and 1/2 fields the
propagators are obtained in the explicit form.
| [
{
"created": "Wed, 13 Sep 2000 23:01:39 GMT",
"version": "v1"
},
{
"created": "Thu, 21 Jun 2001 20:22:12 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Pol'shin",
"Simeon",
""
]
] | Taking the ${\Bbb R}^1 \times H^3$ space as an example, we develop the new method of quantization of fields over symmetric spaces. We construct the quantized massless fields of an arbitrary spin over the ${\Bbb R}^1 \times H^3$ space by the resolution over the systems of "plane waves" which are solutions of the corresponding wave equations. The propagators of these fields are ${\Bbb R}^1 \times SO(3,1)$-invariant and causal. For spin 0 and 1/2 fields the propagators are obtained in the explicit form. |
0805.3955 | Jarmo M\"akel\"a Dr. | J. Makela | A Simple Quantum-Mechanical Model of Spacetime II: Thermodynamics of
Spacetime | 37 pages. This is the second part in a series of two papers, where
the paper gr-qc/0701128 has been divided in two and largely rewritten. In
this version some typos have been corrected, and the paper has been partly
re-organized | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this second part of our series of two papers, where spacetime is modelled
by a graph, where Planck size quantum black holes lie on the vertices, we
consider the thermodynamics of spacetime. We formulate an equation which tells
in which way an accelerating, spacelike two-surface of spacetime interacts with
the thermal radiation flowing through that surface. In the low temperature
limit, where most quantum black holes constituting spacetime are assumed to lie
in the ground state, our equation implies, among other things, the Hawking and
the Unruh effects, as well as Einstein's field equation with a vanishing
cosmological constant for general matter fields. We also consider the high
temperature limit, where the microscopic black holes are assumed to lie in
highly excited states. In this limit our model implies, among other things,
that black hole entropy depends logarithmically on its area, instead of being
proportional to the area.
| [
{
"created": "Mon, 26 May 2008 13:19:57 GMT",
"version": "v1"
},
{
"created": "Sun, 6 Jul 2008 12:45:21 GMT",
"version": "v2"
},
{
"created": "Wed, 21 Oct 2009 11:07:53 GMT",
"version": "v3"
}
] | 2009-10-21 | [
[
"Makela",
"J.",
""
]
] | In this second part of our series of two papers, where spacetime is modelled by a graph, where Planck size quantum black holes lie on the vertices, we consider the thermodynamics of spacetime. We formulate an equation which tells in which way an accelerating, spacelike two-surface of spacetime interacts with the thermal radiation flowing through that surface. In the low temperature limit, where most quantum black holes constituting spacetime are assumed to lie in the ground state, our equation implies, among other things, the Hawking and the Unruh effects, as well as Einstein's field equation with a vanishing cosmological constant for general matter fields. We also consider the high temperature limit, where the microscopic black holes are assumed to lie in highly excited states. In this limit our model implies, among other things, that black hole entropy depends logarithmically on its area, instead of being proportional to the area. |
0811.2615 | Yi Ling | Yi Ling and Qingzhang Wu | The Big Bounce in Rainbow Universe | 8pages, 5figures. Final version published in PLB. | Phys.Lett.B687:103-109,2010 | 10.1016/j.physletb.2010.03.028 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The usual Einstein's equations is modified as a one parameter family of
equations in the framework of rainbow gravity. In this paper we derive the
modified Friedmann-Robertson-Walker (FRW) equations when the cosmological
evolution of radiation particles is taken into account. In particular, given
some specific dispersion relations, the big bounce solutions to the modified
FRW equations can be derived. Notably, to obtain a well defined rainbow metric
at the moment of the big bounce, we find it seems necessary to introduce a
cosmological constant which depends on the energy of probes as well, implying
that a universe with a positive cosmological constant more likely undergoes a
big bounce at least at this phenomenological level.
| [
{
"created": "Mon, 17 Nov 2008 02:53:08 GMT",
"version": "v1"
},
{
"created": "Thu, 1 Apr 2010 02:22:38 GMT",
"version": "v2"
}
] | 2010-04-15 | [
[
"Ling",
"Yi",
""
],
[
"Wu",
"Qingzhang",
""
]
] | The usual Einstein's equations is modified as a one parameter family of equations in the framework of rainbow gravity. In this paper we derive the modified Friedmann-Robertson-Walker (FRW) equations when the cosmological evolution of radiation particles is taken into account. In particular, given some specific dispersion relations, the big bounce solutions to the modified FRW equations can be derived. Notably, to obtain a well defined rainbow metric at the moment of the big bounce, we find it seems necessary to introduce a cosmological constant which depends on the energy of probes as well, implying that a universe with a positive cosmological constant more likely undergoes a big bounce at least at this phenomenological level. |
0905.2424 | Yi Xie | Yi Xie (Nanjing University, China; University of Missouri-Columbia,
USA), Sergei Kopeikin (University of Missouri-Columbia, USA) | Reference Frames, Gauge Transformations and Gravitomagnetism in the
Post-Newtonian Theory of the Lunar Motion | 5 pages, no figure, submitted to Proceedings IAU Symposium No. 261 | null | null | null | gr-qc | http://creativecommons.org/licenses/by-nc-sa/3.0/ | We construct a set of reference frames for description of the orbital and
rotational motion of the Moon. We use a scalar-tensor theory of gravity
depending on two parameters of the parametrized post-Newtonian (PPN) formalism
and utilize the concepts of the relativistic resolutions on reference frames
adopted by the International Astronomical Union in 2000. We assume that the
solar system is isolated and space-time is asymptotically flat. The primary
reference frame has the origin at the solar-system barycenter (SSB) and spatial
axes are going to infinity. The SSB frame is not rotating with respect to
distant quasars. The secondary reference frame has the origin at the Earth-Moon
barycenter (EMB). The EMB frame is local with its spatial axes spreading out to
the orbits of Venus and Mars and not rotating dynamically in the sense that
both the Coriolis and centripetal forces acting on a free-falling test
particle, moving with respect to the EMB frame, are excluded. Two other local
frames, the geocentric (GRF) and the selenocentric (SRF) frames, have the
origin at the center of mass of the Earth and Moon respectively. They are both
introduced in order to connect the coordinate description of the lunar motion,
observer on the Earth, and a retro-reflector on the Moon to the observable
quantities which are the proper time and the laser-ranging distance. We solve
the gravity field equations and find the metric tensor and the scalar field in
all frames. We also derive the post-Newtonian coordinate transformations
between the frames and analyze the residual gauge freedom of the solutions of
the field equations. We discuss the gravitomagnetic effects in the barycentric
equations of the motion of the Moon and argue that they are beyond the current
accuracy of lunar laser ranging (LLR) observations.
| [
{
"created": "Thu, 14 May 2009 20:46:23 GMT",
"version": "v1"
},
{
"created": "Thu, 17 Sep 2009 22:25:59 GMT",
"version": "v2"
},
{
"created": "Mon, 23 Nov 2009 21:51:24 GMT",
"version": "v3"
}
] | 2009-11-23 | [
[
"Xie",
"Yi",
"",
"Nanjing University, China; University of Missouri-Columbia,\n USA"
],
[
"Kopeikin",
"Sergei",
"",
"University of Missouri-Columbia, USA"
]
] | We construct a set of reference frames for description of the orbital and rotational motion of the Moon. We use a scalar-tensor theory of gravity depending on two parameters of the parametrized post-Newtonian (PPN) formalism and utilize the concepts of the relativistic resolutions on reference frames adopted by the International Astronomical Union in 2000. We assume that the solar system is isolated and space-time is asymptotically flat. The primary reference frame has the origin at the solar-system barycenter (SSB) and spatial axes are going to infinity. The SSB frame is not rotating with respect to distant quasars. The secondary reference frame has the origin at the Earth-Moon barycenter (EMB). The EMB frame is local with its spatial axes spreading out to the orbits of Venus and Mars and not rotating dynamically in the sense that both the Coriolis and centripetal forces acting on a free-falling test particle, moving with respect to the EMB frame, are excluded. Two other local frames, the geocentric (GRF) and the selenocentric (SRF) frames, have the origin at the center of mass of the Earth and Moon respectively. They are both introduced in order to connect the coordinate description of the lunar motion, observer on the Earth, and a retro-reflector on the Moon to the observable quantities which are the proper time and the laser-ranging distance. We solve the gravity field equations and find the metric tensor and the scalar field in all frames. We also derive the post-Newtonian coordinate transformations between the frames and analyze the residual gauge freedom of the solutions of the field equations. We discuss the gravitomagnetic effects in the barycentric equations of the motion of the Moon and argue that they are beyond the current accuracy of lunar laser ranging (LLR) observations. |
1506.01247 | Varun Sahni | Varun Sahni, Yuri Shtanov, Aleksey Toporensky | Arrow of time in dissipationless cosmology | 19 pages, 6 figures. Matches published version in Class. Quantum
Grav. 32 (2015) 182001 (Fast Track Communication) | Class. Quantum Grav. 32 (2015) 182001 | 10.1088/0264-9381/32/18/182001 | null | gr-qc astro-ph.CO hep-ph hep-th physics.pop-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is generally believed that a cosmological arrow of time must be associated
with entropy production. Indeed, in his seminal work on cyclic cosmology,
Tolman introduced a viscous fluid in order to make successive
expansion/contraction cycles larger than previous ones, thereby generating an
arrow of time. However, as we demonstrate in this letter, the production of
entropy is not the only means by which a cosmological arrow of time may emerge.
Remarkably, systems which are dissipationless may nevertheless demonstrate a
preferred direction of time provided they possess attractors. An example of a
system with well defined attractors is scalar-field driven cosmology. In this
case, for a wide class of potentials (especially those responsible for
inflation), the attractor equation of state during expansion can have the form
$p \simeq -\rho$, and during contraction $p \simeq \rho$. If the resulting
cosmology is cyclic, then the presence of cosmological hysteresis, $\oint p~dV
\neq 0$ during successive cycles, causes an arrow of time to emerge in a system
which is formally dissipationless. An important analogy is drawn between the
arrow of time in cyclic cosmology and an arrow of time in an $N$-body system of
gravitationally interacting particles. We find that, like the $N$-body system,
a cyclic universe can evolve from a single past into two futures with
oppositely directed arrows of time.
| [
{
"created": "Wed, 3 Jun 2015 14:02:21 GMT",
"version": "v1"
},
{
"created": "Tue, 11 Aug 2015 12:37:42 GMT",
"version": "v2"
},
{
"created": "Fri, 28 Aug 2015 08:50:35 GMT",
"version": "v3"
}
] | 2018-10-26 | [
[
"Sahni",
"Varun",
""
],
[
"Shtanov",
"Yuri",
""
],
[
"Toporensky",
"Aleksey",
""
]
] | It is generally believed that a cosmological arrow of time must be associated with entropy production. Indeed, in his seminal work on cyclic cosmology, Tolman introduced a viscous fluid in order to make successive expansion/contraction cycles larger than previous ones, thereby generating an arrow of time. However, as we demonstrate in this letter, the production of entropy is not the only means by which a cosmological arrow of time may emerge. Remarkably, systems which are dissipationless may nevertheless demonstrate a preferred direction of time provided they possess attractors. An example of a system with well defined attractors is scalar-field driven cosmology. In this case, for a wide class of potentials (especially those responsible for inflation), the attractor equation of state during expansion can have the form $p \simeq -\rho$, and during contraction $p \simeq \rho$. If the resulting cosmology is cyclic, then the presence of cosmological hysteresis, $\oint p~dV \neq 0$ during successive cycles, causes an arrow of time to emerge in a system which is formally dissipationless. An important analogy is drawn between the arrow of time in cyclic cosmology and an arrow of time in an $N$-body system of gravitationally interacting particles. We find that, like the $N$-body system, a cyclic universe can evolve from a single past into two futures with oppositely directed arrows of time. |
2112.04609 | Juan Manuel L\'opez-Vega | Pasquale Bosso and Juan Manuel L\'opez Vega | Minimal Length Phenomenology and the Black Body Radiation | 15 pages, 3 figures | null | 10.1088/1361-6382/ac821c | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The generalized uncertainty principle (GUP) modifies the uncertainty relation
between momentum and position giving room for a minimal length, as predicted by
candidates theories of quantum gravity. Inspired by GUP, Planck's distribution
is derived by considering a new quantization of the electromagnetic field. We
elaborate on the thermodynamics of the black body radiation obtaining Wien's
law and the Stefan-Boltzmann law. We show that such thermodynamics laws are
modified at Planck-scale.
| [
{
"created": "Wed, 8 Dec 2021 22:36:48 GMT",
"version": "v1"
}
] | 2022-08-24 | [
[
"Bosso",
"Pasquale",
""
],
[
"Vega",
"Juan Manuel López",
""
]
] | The generalized uncertainty principle (GUP) modifies the uncertainty relation between momentum and position giving room for a minimal length, as predicted by candidates theories of quantum gravity. Inspired by GUP, Planck's distribution is derived by considering a new quantization of the electromagnetic field. We elaborate on the thermodynamics of the black body radiation obtaining Wien's law and the Stefan-Boltzmann law. We show that such thermodynamics laws are modified at Planck-scale. |
1405.7846 | Hor\'acio Santana Vieira | H. S. Vieira, V. B. Bezerra and Andr\'e A. Costa | Scalar fields in the Lense-Thirring background with a cosmic string and
Hawking radiation | 6 pages | EPL 109 (2015) 60006 | 10.1209/0295-5075/109/60006 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyze the influence of the gravitational field produced by a slowly
rotating black hole with a cosmic string along the axis of symmetry on a
massive scalar field. Exact solutions of both angular and radial parts of the
Klein-Gordon equation in this spacetime are obtained, and are given in terms of
the confluent Heun functions. We emphasize the role of the presence of the
cosmic string in these solutions. We also investigate the solutions in regions
near and far from the event horizon. From the radial solution, we obtain the
exact wave solutions near the exterior horizon of the black hole, and discuss
the Hawking radiation of massive scalar particles.
| [
{
"created": "Fri, 30 May 2014 13:04:14 GMT",
"version": "v1"
},
{
"created": "Sat, 11 Apr 2015 11:12:43 GMT",
"version": "v2"
}
] | 2015-04-14 | [
[
"Vieira",
"H. S.",
""
],
[
"Bezerra",
"V. B.",
""
],
[
"Costa",
"André A.",
""
]
] | We analyze the influence of the gravitational field produced by a slowly rotating black hole with a cosmic string along the axis of symmetry on a massive scalar field. Exact solutions of both angular and radial parts of the Klein-Gordon equation in this spacetime are obtained, and are given in terms of the confluent Heun functions. We emphasize the role of the presence of the cosmic string in these solutions. We also investigate the solutions in regions near and far from the event horizon. From the radial solution, we obtain the exact wave solutions near the exterior horizon of the black hole, and discuss the Hawking radiation of massive scalar particles. |
0901.3881 | Hideo Kodama | Hideo Kodama | Repulsons in the 5D Myers-Perry Family | 4 pages, 2 figures. A talk given at JGRG18 (Hiroshima U, Japan, 18-21
Nov. 2008) | null | null | KEK-Cosmo-22 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this talk, we point out that curvature-regular asymptotically flat
solitons with negative mass are contained in the Myers-Perry family in five
dimensions. These solitons do not have horizon, but instead a conical NUT
singularity of quasi-regular nature surrounded by naked CTCs. We show that this
quasi-regular singularity can be made regular for a set of discrete values of
angular momentum by introducing some periodic identifications, at least in the
case in which two angular momentum parameters are equal. Although the spatial
infinity of the solitons is diffeomorphic to S^1xS^3/R_n (n>2), the
corresponding spacetime is simply connected and asymptotically flat.
| [
{
"created": "Sun, 25 Jan 2009 08:44:11 GMT",
"version": "v1"
}
] | 2009-01-27 | [
[
"Kodama",
"Hideo",
""
]
] | In this talk, we point out that curvature-regular asymptotically flat solitons with negative mass are contained in the Myers-Perry family in five dimensions. These solitons do not have horizon, but instead a conical NUT singularity of quasi-regular nature surrounded by naked CTCs. We show that this quasi-regular singularity can be made regular for a set of discrete values of angular momentum by introducing some periodic identifications, at least in the case in which two angular momentum parameters are equal. Although the spatial infinity of the solitons is diffeomorphic to S^1xS^3/R_n (n>2), the corresponding spacetime is simply connected and asymptotically flat. |
1805.11009 | Z. Yousaf | Wajiha Javed, Z. Yousaf, Zunaira Akhtar | Thermodynamics and Glassy Phase Transition of Regular Black Holes | 26 pages, 11 figures | Mod. Phys. Lett. A 33, 1850089 (2018) | 10.1142/S021773231850089X | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The present paper is aimed to study thermodynamical properties of phase
transition for regular charged black holes. In this context, we have considered
two different forms of black hole metrics supplemented with exponential and
logistic distribution functions and investigated the recent expansion of phase
transition through grand canonical ensemble. After exploring the corresponding
Ehrenfest's equation, we found the second order background of phase transition
at critical points. In order to check the critical behavior of regular black
holes, we have evaluated some corresponding explicit relations for the critical
temperature, pressure and volume and draw certain graphs with constant values
of Smarr's mass. We found that for the BH metric with exponential configuration
function, the phase transition curves are divergent near the critical points,
while glassy phase transition has been observed for the
Ay\'{o}n-Beato-Garc\'{i}a-Bronnikov BH in $n=5$ dimensions.
| [
{
"created": "Thu, 24 May 2018 09:03:28 GMT",
"version": "v1"
},
{
"created": "Tue, 29 May 2018 12:39:45 GMT",
"version": "v2"
}
] | 2018-05-30 | [
[
"Javed",
"Wajiha",
""
],
[
"Yousaf",
"Z.",
""
],
[
"Akhtar",
"Zunaira",
""
]
] | The present paper is aimed to study thermodynamical properties of phase transition for regular charged black holes. In this context, we have considered two different forms of black hole metrics supplemented with exponential and logistic distribution functions and investigated the recent expansion of phase transition through grand canonical ensemble. After exploring the corresponding Ehrenfest's equation, we found the second order background of phase transition at critical points. In order to check the critical behavior of regular black holes, we have evaluated some corresponding explicit relations for the critical temperature, pressure and volume and draw certain graphs with constant values of Smarr's mass. We found that for the BH metric with exponential configuration function, the phase transition curves are divergent near the critical points, while glassy phase transition has been observed for the Ay\'{o}n-Beato-Garc\'{i}a-Bronnikov BH in $n=5$ dimensions. |
2406.02109 | Bekir Can L\"utf\"uo\u{g}lu | B. Hamil and B. C. L\"utf\"uo\u{g}lu | Euler-Heisenberg black hole surrounded by quintessence in the background
of perfect fluid dark matter: Thermodynamics, Shadows and Quasinormal modes | 23 Figures, 8 Tables, and 25 Pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Current observations show that a significant fraction of the Universe is
composed of dark energy and dark matter. In this paper, we investigate the
simultaneous effects of these dark sectors on the Euler-Heisenberg black hole,
using the quintessence matter field and perfect fluid to model them. In
particular, we study the black hole's thermodynamics, shadows, and quasinormal
modes, and discuss in detail how these properties change with relatively large
or small dark sector components.
| [
{
"created": "Tue, 4 Jun 2024 08:36:21 GMT",
"version": "v1"
}
] | 2024-06-05 | [
[
"Hamil",
"B.",
""
],
[
"Lütfüoğlu",
"B. C.",
""
]
] | Current observations show that a significant fraction of the Universe is composed of dark energy and dark matter. In this paper, we investigate the simultaneous effects of these dark sectors on the Euler-Heisenberg black hole, using the quintessence matter field and perfect fluid to model them. In particular, we study the black hole's thermodynamics, shadows, and quasinormal modes, and discuss in detail how these properties change with relatively large or small dark sector components. |
1512.07152 | Saravanan Satish Kumar | S. Satish Kumar | Motion of a spinning particle in curved space-time | 6 pages, to be published in the Proceedings of the Fourteenth Marcel
Grossmann Meeting - MG14 (World Scientific) | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The motion of spinning test-masses in curved space-time is described with a
covariant hamiltonian formalism. A large class of hamiltonians can be used with
the model- independent Poisson-Dirac brackets, to obtain equations of motion.
Here we apply it to the minimal hamiltonian and also to a non-minimal
hamiltonian, describing the gravi- tational Stern-Gerlach force. And a note on
ISCO has been added.
| [
{
"created": "Tue, 22 Dec 2015 16:43:39 GMT",
"version": "v1"
}
] | 2015-12-23 | [
[
"Kumar",
"S. Satish",
""
]
] | The motion of spinning test-masses in curved space-time is described with a covariant hamiltonian formalism. A large class of hamiltonians can be used with the model- independent Poisson-Dirac brackets, to obtain equations of motion. Here we apply it to the minimal hamiltonian and also to a non-minimal hamiltonian, describing the gravi- tational Stern-Gerlach force. And a note on ISCO has been added. |
1204.5466 | Cenalo Vaz | Cenalo Vaz and Kinjalk Lochan | Tunneling during Quantum Collapse in AdS Spacetime | 14 pages. No figures. Title changed to published version | Phys. Rev. D 87, 024045 (2013) | 10.1103/PhysRevD.87.024045 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We extend previous results on the reflection and transmission of
self-gravitating dust shells across the apparent horizon during quantum dust
collapse to non-marginally-bound dust collapse in arbitrary dimensions with a
negative cosmological constant. We show that the Hawking temperature is
independent of the energy function and that the wave functional describing the
collapse is well behaved at the Hawking-Page transition point. Thermal
radiation from the apparent horizon appears as a generic result of non-marginal
collapse in AdS space-time owing to the singular structure of the Hamiltonian
constraint at the apparent horizon.
| [
{
"created": "Tue, 24 Apr 2012 19:33:04 GMT",
"version": "v1"
},
{
"created": "Wed, 30 Jan 2013 18:35:13 GMT",
"version": "v2"
}
] | 2013-01-31 | [
[
"Vaz",
"Cenalo",
""
],
[
"Lochan",
"Kinjalk",
""
]
] | We extend previous results on the reflection and transmission of self-gravitating dust shells across the apparent horizon during quantum dust collapse to non-marginally-bound dust collapse in arbitrary dimensions with a negative cosmological constant. We show that the Hawking temperature is independent of the energy function and that the wave functional describing the collapse is well behaved at the Hawking-Page transition point. Thermal radiation from the apparent horizon appears as a generic result of non-marginal collapse in AdS space-time owing to the singular structure of the Hamiltonian constraint at the apparent horizon. |
1703.02058 | Christian Pfeifer | Leonardo Barcaroli, Lukas K. Brunkhorst, Giulia Gubitosi, Niccol\'o
Loret, Christian Pfeifer | Curved spacetimes with local $\kappa$-Poincar\'e dispersion relation | 28 pages, updated to accepted journal version, appendix on
kappa-Poincare electrodynamics added | Phys. Rev. D 96, 084010 (2017) | 10.1103/PhysRevD.96.084010 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We use our previously developed identification of dispersion relations with
Hamilton functions on phase space to locally implement the $\kappa$-Poincar\'e
dispersion relation in the momentum spaces at each point of a generic curved
spacetime. We use this general construction to build the most general
Hamiltonian compatible with spherical symmetry and the Plank-scale-deformed one
such that in the local frame it reproduces the $\kappa$-Poincar\'e dispersion
relation. Specializing to Planck-scale-deformed Schwarzschild geometry, we find
that the photon sphere around a black hole becomes a thick shell since photons
of different energy will orbit the black hole on circular orbits at different
altitudes. We also compute the redshift of a photon between different observers
at rest, finding that there is a Planck-scale correction to the usual redshift
only if the observers detecting the photon have different masses.
| [
{
"created": "Mon, 6 Mar 2017 19:01:01 GMT",
"version": "v1"
},
{
"created": "Mon, 9 Oct 2017 05:50:11 GMT",
"version": "v2"
}
] | 2017-10-10 | [
[
"Barcaroli",
"Leonardo",
""
],
[
"Brunkhorst",
"Lukas K.",
""
],
[
"Gubitosi",
"Giulia",
""
],
[
"Loret",
"Niccoló",
""
],
[
"Pfeifer",
"Christian",
""
]
] | We use our previously developed identification of dispersion relations with Hamilton functions on phase space to locally implement the $\kappa$-Poincar\'e dispersion relation in the momentum spaces at each point of a generic curved spacetime. We use this general construction to build the most general Hamiltonian compatible with spherical symmetry and the Plank-scale-deformed one such that in the local frame it reproduces the $\kappa$-Poincar\'e dispersion relation. Specializing to Planck-scale-deformed Schwarzschild geometry, we find that the photon sphere around a black hole becomes a thick shell since photons of different energy will orbit the black hole on circular orbits at different altitudes. We also compute the redshift of a photon between different observers at rest, finding that there is a Planck-scale correction to the usual redshift only if the observers detecting the photon have different masses. |
2405.05011 | Xiangyu Wang | Xiangyu Wang, Xiaobao Wang, Hai-Qing Zhang, Minyong Guo | Is a photon ring invariably a closed structure? | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this study, we investigate the image of a rotating compact object (CO)
illuminated by a geometrically thin, optically thin disk on the equatorial
plane. As the radius of the CO's surface fluctuates, the CO may partially or
entirely obscure the photon region. We observe that the perceived photon ring
may exhibit discontinuities, deviating from a closed structure, and may even
disappear entirely. We find that the disruption and disappearance of the photon
ring are dependent on the observational angle$-$a novel phenomenon not
previously observed in black hole imaging studies. Our study reveals that while
the factors influencing this unique photon ring phenomenon are diverse and the
outcomes complex, we can provide a clear and comprehensive explanation of the
physical essence and variation trends of this phenomenon. We do this by
introducing and analyzing the properties and interrelationships of three
characteristic functions, $\tilde{\eta}$, $\eta_o$, and $\eta_s$ related to the
photon impact parameters. Additionally, our analysis of the intensity cuts and
inner shadows of the images uncovers patterns that differ significantly from
the shadow curve.
| [
{
"created": "Wed, 8 May 2024 12:25:53 GMT",
"version": "v1"
}
] | 2024-05-09 | [
[
"Wang",
"Xiangyu",
""
],
[
"Wang",
"Xiaobao",
""
],
[
"Zhang",
"Hai-Qing",
""
],
[
"Guo",
"Minyong",
""
]
] | In this study, we investigate the image of a rotating compact object (CO) illuminated by a geometrically thin, optically thin disk on the equatorial plane. As the radius of the CO's surface fluctuates, the CO may partially or entirely obscure the photon region. We observe that the perceived photon ring may exhibit discontinuities, deviating from a closed structure, and may even disappear entirely. We find that the disruption and disappearance of the photon ring are dependent on the observational angle$-$a novel phenomenon not previously observed in black hole imaging studies. Our study reveals that while the factors influencing this unique photon ring phenomenon are diverse and the outcomes complex, we can provide a clear and comprehensive explanation of the physical essence and variation trends of this phenomenon. We do this by introducing and analyzing the properties and interrelationships of three characteristic functions, $\tilde{\eta}$, $\eta_o$, and $\eta_s$ related to the photon impact parameters. Additionally, our analysis of the intensity cuts and inner shadows of the images uncovers patterns that differ significantly from the shadow curve. |
1702.07166 | Krishnakanta Bhattacharya | Krishnakanta Bhattacharya, Bibhas Ranjan Majhi | Fresh look at the scalar-tensor theory of gravity in Jordan and Einstein
frames from undiscussed standpoints | Typos corrected, published in Phys. Rev. D | Phys. Rev. D95 (2017) 064026 | 10.1103/PhysRevD.95.064026 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the scalar-tensor theory of gravity profoundly in the action level
as well as in the thermodynamic level. Contrary to the usual description in the
literature about the equivalence in the two conformally connected frames, this
paper addresses several incomplete inferences regarding it and mentions some
inequivalences which were not pointed out earlier. In the thermodynamic level,
our analysis shows the two frames are equivalent. In that process, we identify
the entropy, the energy and the temperature for the thermodynamic description,
and we find these quantities are conformally invariant even without any prior
assumption. The same conclusion is reached from the gravitational action as
well as from the Gibbons-Hawking-York boundary term, establishing the result in
a more convincing manner.
| [
{
"created": "Thu, 23 Feb 2017 10:49:06 GMT",
"version": "v1"
},
{
"created": "Fri, 17 Mar 2017 11:04:58 GMT",
"version": "v2"
}
] | 2017-05-19 | [
[
"Bhattacharya",
"Krishnakanta",
""
],
[
"Majhi",
"Bibhas Ranjan",
""
]
] | We study the scalar-tensor theory of gravity profoundly in the action level as well as in the thermodynamic level. Contrary to the usual description in the literature about the equivalence in the two conformally connected frames, this paper addresses several incomplete inferences regarding it and mentions some inequivalences which were not pointed out earlier. In the thermodynamic level, our analysis shows the two frames are equivalent. In that process, we identify the entropy, the energy and the temperature for the thermodynamic description, and we find these quantities are conformally invariant even without any prior assumption. The same conclusion is reached from the gravitational action as well as from the Gibbons-Hawking-York boundary term, establishing the result in a more convincing manner. |
2406.05851 | C\'edric Jockel | C\'edric Jockel and Leon Menger | The Effect of Torsion on Neutron Star Structure in Einstein-Cartan
Gravity | 19 pages, 4 figures | null | null | null | gr-qc astro-ph.HE hep-th | http://creativecommons.org/licenses/by-sa/4.0/ | Einstein--Cartan gravity is a close historical sibling of general relativity
that allows for spacetime torsion. As a result, angular momentum couples to
spacetime geometry in a similar way to energy. While consequences of this are
well studied on cosmological scales, their role in neutron star physics is
largely under-explored. We study the effects that torsion, sourced by either
microphysical spin or macroscopic angular momentum, has on neutron stars. For
this, we use a simplified polytropic model to quantify the microphysical
coupling to torsion. We also derive expressions to model rotation-induced
torsion effects and estimate the consequences for rotating neutron stars with
different rotation rates. We find that the presence of torsion in general leads
to neutron stars with smaller radii and masses, but higher central densities.
Realistic models for microphysical spin lead to torsion effects that have no
relevant influence on the neutron star structure. Rotation-induced torsion
effects however, can decrease the radius by up to $900\,m$, which is comparable
to the increase due to centrifugal forces. Depending on which effect dominates,
this leads to a torsion-induced spin-up or spin-down of the neutron star. We
conclude that torsion effects due to rotation can not be neglected and are
large enough to be tested using current or near-future technology.
| [
{
"created": "Sun, 9 Jun 2024 16:49:30 GMT",
"version": "v1"
}
] | 2024-06-11 | [
[
"Jockel",
"Cédric",
""
],
[
"Menger",
"Leon",
""
]
] | Einstein--Cartan gravity is a close historical sibling of general relativity that allows for spacetime torsion. As a result, angular momentum couples to spacetime geometry in a similar way to energy. While consequences of this are well studied on cosmological scales, their role in neutron star physics is largely under-explored. We study the effects that torsion, sourced by either microphysical spin or macroscopic angular momentum, has on neutron stars. For this, we use a simplified polytropic model to quantify the microphysical coupling to torsion. We also derive expressions to model rotation-induced torsion effects and estimate the consequences for rotating neutron stars with different rotation rates. We find that the presence of torsion in general leads to neutron stars with smaller radii and masses, but higher central densities. Realistic models for microphysical spin lead to torsion effects that have no relevant influence on the neutron star structure. Rotation-induced torsion effects however, can decrease the radius by up to $900\,m$, which is comparable to the increase due to centrifugal forces. Depending on which effect dominates, this leads to a torsion-induced spin-up or spin-down of the neutron star. We conclude that torsion effects due to rotation can not be neglected and are large enough to be tested using current or near-future technology. |
0901.4465 | Pac\^ome Delva Dr. | P. Delva and M.-C. Angonin | Extended Fermi coordinates | 16 pages, 1 figure | null | 10.1007/s10714-011-1272-9 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We extend the notion of Fermi coordinates to a generalized definition in
which the highest orders are described by arbitrary functions. From this
definition rises a formalism that naturally gives coordinate transformation
formulae. Some examples are developped in which the extended Fermi coordinates
simplify the metric components.
| [
{
"created": "Wed, 28 Jan 2009 14:11:57 GMT",
"version": "v1"
},
{
"created": "Mon, 12 Jul 2010 10:53:32 GMT",
"version": "v2"
}
] | 2015-05-13 | [
[
"Delva",
"P.",
""
],
[
"Angonin",
"M. -C.",
""
]
] | We extend the notion of Fermi coordinates to a generalized definition in which the highest orders are described by arbitrary functions. From this definition rises a formalism that naturally gives coordinate transformation formulae. Some examples are developped in which the extended Fermi coordinates simplify the metric components. |
2110.15951 | Raghvendra Singh | Raghvendra Singh and Dawood Kothawala | Covariant formulation of Generalised Uncertainty Principle | 6 pages, 3 figures, published as a Letter in Physical Review D | Phys. Rev. D 105, L101501 (2022) | 10.1103/PhysRevD.105.L101501 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We present a formulation of the generalised uncertainty principle based on
commutator $\left[ {\hat x}^i, {\hat p}_j \right]$ between position and
momentum operators defined in a covariant manner using normal coordinates. We
show how any such commutator can acquire corrections if the momentum space is
curved. The correction is completely determined by the extrinsic curvature of
the surface $p^2=$ constant in the momentum space, and results in
non-commutativity of normal position coordinates $\left[ {\hat x}^i, {\hat x}^j
\right] \neq 0$. We then provide a construction for the momentum space geometry
as a suitable four dimensional extension of a geometry conformal to the three
dimensional relativistic velocity space - the Lobachevsky space - whose
curvature is determined by the dispersion relation $F(p^2)=-m^2$, with $F(x)=x$
yielding the standard Heisenberg algebra.
| [
{
"created": "Fri, 29 Oct 2021 17:55:35 GMT",
"version": "v1"
},
{
"created": "Sun, 21 Nov 2021 13:10:09 GMT",
"version": "v2"
},
{
"created": "Wed, 18 May 2022 15:45:21 GMT",
"version": "v3"
}
] | 2022-05-19 | [
[
"Singh",
"Raghvendra",
""
],
[
"Kothawala",
"Dawood",
""
]
] | We present a formulation of the generalised uncertainty principle based on commutator $\left[ {\hat x}^i, {\hat p}_j \right]$ between position and momentum operators defined in a covariant manner using normal coordinates. We show how any such commutator can acquire corrections if the momentum space is curved. The correction is completely determined by the extrinsic curvature of the surface $p^2=$ constant in the momentum space, and results in non-commutativity of normal position coordinates $\left[ {\hat x}^i, {\hat x}^j \right] \neq 0$. We then provide a construction for the momentum space geometry as a suitable four dimensional extension of a geometry conformal to the three dimensional relativistic velocity space - the Lobachevsky space - whose curvature is determined by the dispersion relation $F(p^2)=-m^2$, with $F(x)=x$ yielding the standard Heisenberg algebra. |
2010.08181 | Raul Jimenez | Ali Rida Khalifeh, Raul Jimenez | Spinors and Scalars in curved spacetime: neutrino dark energy
(DE$_{\nu}$) | Matches version accepted by the Journal (Physics of the Dark
Universe) | Physics of the Dark Universe. 31, 100777, 2021 | null | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the interaction, in general curved spacetime, between a spinor and a
scalar field describing dark energy; the so-called DE$_{\nu}$ model in curved
space. The dominant term is the dimension 5 operator, which results in
different energy shifts for the neutrino states: an Aharonov-Bohm-like effect.
We study the phenomenology of this term and make observational predictions to
detect dark energy interactions in the laboratory due to its effect on neutrino
oscillation experiments, which opens up the possibility of designing
underground experiments to detect dark energy. This dimension 5 operator beyond
the Standard Model interaction is less suppressed than the widely discussed
dimension 6 operator, which corresponds to mass varying neutrinos; the
dimension 5 operator does not suffer from gravitational instabilities.
| [
{
"created": "Fri, 16 Oct 2020 06:03:06 GMT",
"version": "v1"
},
{
"created": "Mon, 25 Jan 2021 11:28:21 GMT",
"version": "v2"
}
] | 2022-01-24 | [
[
"Khalifeh",
"Ali Rida",
""
],
[
"Jimenez",
"Raul",
""
]
] | We study the interaction, in general curved spacetime, between a spinor and a scalar field describing dark energy; the so-called DE$_{\nu}$ model in curved space. The dominant term is the dimension 5 operator, which results in different energy shifts for the neutrino states: an Aharonov-Bohm-like effect. We study the phenomenology of this term and make observational predictions to detect dark energy interactions in the laboratory due to its effect on neutrino oscillation experiments, which opens up the possibility of designing underground experiments to detect dark energy. This dimension 5 operator beyond the Standard Model interaction is less suppressed than the widely discussed dimension 6 operator, which corresponds to mass varying neutrinos; the dimension 5 operator does not suffer from gravitational instabilities. |
1910.05630 | Elena Giorgi | Elena Giorgi | The linear stability of Reissner-Nordstr\"om spacetime: the full
subextremal range | 45 pages, 1 figure, version accepted for publication | Commun. Math. Phys. 380, 1313-1360 (2020) | 10.1007/s00220-020-03893-z | null | gr-qc math-ph math.AP math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We prove the linear stability of subextremal Reissner-Nordstr\"om spacetimes
as solutions to the Einstein-Maxwell equation. We make use of a novel
representation of gauge-invariant quantities which satisfy a symmetric system
of coupled wave equations. This system is composed of two of the three
equations separately derived in previous works, where the estimates required
arbitrary smallness of the charge. Here, the estimates are obtained by defining
a combined energy-momentum tensor for the system in terms of the symmetric
structure of the right hand sides of the equations. We obtain boundedness of
the energy, Morawetz estimates and decay for the full subextremal range |Q|<M,
completely in physical space. Such decay estimates, together with the estimates
for the gauge-dependent quantities of the perturbations previously obtained,
settle the problem of linear stability to gravitational and electromagnetic
perturbations of Reissner-Nordstr\"om solution in the full subextremal range
|Q|< M.
| [
{
"created": "Sat, 12 Oct 2019 19:09:02 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Nov 2021 17:04:19 GMT",
"version": "v2"
}
] | 2021-11-29 | [
[
"Giorgi",
"Elena",
""
]
] | We prove the linear stability of subextremal Reissner-Nordstr\"om spacetimes as solutions to the Einstein-Maxwell equation. We make use of a novel representation of gauge-invariant quantities which satisfy a symmetric system of coupled wave equations. This system is composed of two of the three equations separately derived in previous works, where the estimates required arbitrary smallness of the charge. Here, the estimates are obtained by defining a combined energy-momentum tensor for the system in terms of the symmetric structure of the right hand sides of the equations. We obtain boundedness of the energy, Morawetz estimates and decay for the full subextremal range |Q|<M, completely in physical space. Such decay estimates, together with the estimates for the gauge-dependent quantities of the perturbations previously obtained, settle the problem of linear stability to gravitational and electromagnetic perturbations of Reissner-Nordstr\"om solution in the full subextremal range |Q|< M. |
1408.5897 | Florian Kuhnel | Florian Kuhnel | Thoughts on the Vacuum Energy in the Quantum N-Portrait | 7 pages; revised version to match published version | Mod.Phys.Lett. A30 (2015) 36, 1550197 | 10.1142/S0217732315501977 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An application of the quantum N-portrait to the Universe is discussed,
wherein the space-time geometry is understood as a Bose-Einstein condensate of
N soft gravitons. If near or at the critical point of a quantum phase
transition, indications are found that the vacuum energy is partly suppressed
by 1/N, as being due to quanta not in the condensate state. Time evolution
decreases this suppression, which might have implications for cosmic expansion.
| [
{
"created": "Mon, 25 Aug 2014 20:00:03 GMT",
"version": "v1"
},
{
"created": "Mon, 31 Aug 2015 12:06:34 GMT",
"version": "v2"
},
{
"created": "Wed, 21 Oct 2015 06:47:02 GMT",
"version": "v3"
}
] | 2015-10-22 | [
[
"Kuhnel",
"Florian",
""
]
] | An application of the quantum N-portrait to the Universe is discussed, wherein the space-time geometry is understood as a Bose-Einstein condensate of N soft gravitons. If near or at the critical point of a quantum phase transition, indications are found that the vacuum energy is partly suppressed by 1/N, as being due to quanta not in the condensate state. Time evolution decreases this suppression, which might have implications for cosmic expansion. |
gr-qc/0307083 | Martin Bojowald | Martin Bojowald and Ghanashyam Date | Consistency Conditions for Fundamentally Discrete Theories | 33 pages | Class.Quant.Grav. 21 (2004) 121-143 | 10.1088/0264-9381/21/1/009 | IMSc/2003/07/17 | gr-qc hep-th | null | The dynamics of physical theories is usually described by differential
equations. Difference equations then appear mainly as an approximation which
can be used for a numerical analysis. As such, they have to fulfill certain
conditions to ensure that the numerical solutions can reliably be used as
approximations to solutions of the differential equation. There are, however,
also systems where a difference equation is deemed to be fundamental, mainly in
the context of quantum gravity. Since difference equations in general are
harder to solve analytically than differential equations, it can be helpful to
introduce an approximating differential equation as a continuum approximation.
In this paper implications of this change in view point are analyzed to derive
the conditions that the difference equation should satisfy. The difference
equation in such a situation cannot be chosen freely but must be derived from a
fundamental theory. Thus, the conditions for a discrete formulation can be
translated into conditions for acceptable quantizations. In the main example,
loop quantum cosmology, we show that the conditions are restrictive and serve
as a selection criterion among possible quantization choices.
| [
{
"created": "Thu, 17 Jul 2003 15:43:46 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Bojowald",
"Martin",
""
],
[
"Date",
"Ghanashyam",
""
]
] | The dynamics of physical theories is usually described by differential equations. Difference equations then appear mainly as an approximation which can be used for a numerical analysis. As such, they have to fulfill certain conditions to ensure that the numerical solutions can reliably be used as approximations to solutions of the differential equation. There are, however, also systems where a difference equation is deemed to be fundamental, mainly in the context of quantum gravity. Since difference equations in general are harder to solve analytically than differential equations, it can be helpful to introduce an approximating differential equation as a continuum approximation. In this paper implications of this change in view point are analyzed to derive the conditions that the difference equation should satisfy. The difference equation in such a situation cannot be chosen freely but must be derived from a fundamental theory. Thus, the conditions for a discrete formulation can be translated into conditions for acceptable quantizations. In the main example, loop quantum cosmology, we show that the conditions are restrictive and serve as a selection criterion among possible quantization choices. |
gr-qc/0608118 | Gregory J. Galloway | Gregory J. Galloway | Rigidity of marginally trapped surfaces and the topology of black holes | 11 pages, latex2e; v4: minor corrections, references updated in
preparation for publication; to appear in Commun. Anal. Geom | null | null | null | gr-qc hep-th math.DG | null | In a recent paper (gr-qc/0509107) the author and Rick Schoen obtained a
generalization to higher dimensions of a classical result of Hawking concerning
the topology of black holes. It was proved that, apart from certain exceptional
circumstances, cross sections of the event horizon, in the stationary case, and
'weakly outermost' marginally outer trapped surfaces, in the general case, in
black hole spacetimes obeying the dominant energy condition, are of positive
Yamabe type. This implies many well-known restrictions on the topology, and is
consistent with recent examples of five dimensional stationary black hole
spacetimes with horizon topology $S^2 \times S^1$. In the present paper, we
rule out for 'outermost' marginally outer trapped surfaces, in particular, for
cross sections of the event horizon in stationary black hole spacetimes, the
possibility of any such exceptional circumstances (which might have permitted,
e.g., toroidal cross sections). This follows from the main result, which is a
rigidity result for marginally outer trapped surfaces that are not of positive
Yamabe type.
| [
{
"created": "Mon, 28 Aug 2006 18:01:09 GMT",
"version": "v1"
},
{
"created": "Mon, 26 Mar 2007 12:27:55 GMT",
"version": "v2"
},
{
"created": "Sat, 15 Sep 2007 14:20:00 GMT",
"version": "v3"
},
{
"created": "Mon, 14 Jan 2008 16:05:34 GMT",
"version": "v4"
}
] | 2008-01-14 | [
[
"Galloway",
"Gregory J.",
""
]
] | In a recent paper (gr-qc/0509107) the author and Rick Schoen obtained a generalization to higher dimensions of a classical result of Hawking concerning the topology of black holes. It was proved that, apart from certain exceptional circumstances, cross sections of the event horizon, in the stationary case, and 'weakly outermost' marginally outer trapped surfaces, in the general case, in black hole spacetimes obeying the dominant energy condition, are of positive Yamabe type. This implies many well-known restrictions on the topology, and is consistent with recent examples of five dimensional stationary black hole spacetimes with horizon topology $S^2 \times S^1$. In the present paper, we rule out for 'outermost' marginally outer trapped surfaces, in particular, for cross sections of the event horizon in stationary black hole spacetimes, the possibility of any such exceptional circumstances (which might have permitted, e.g., toroidal cross sections). This follows from the main result, which is a rigidity result for marginally outer trapped surfaces that are not of positive Yamabe type. |
1601.05086 | Carlos O. Lousto | Carlos O. Lousto and James Healy | Unstable flip-flopping spinning binary black holes | 5 pages, 3 figures | Phys. Rev. D 93, 124074 (2016) | 10.1103/PhysRevD.93.124074 | null | gr-qc astro-ph.CO astro-ph.GA astro-ph.SR hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We give a unified description of the flip-flop effect in spinning binary
black holes and the anti-alignment instability in terms of real and imaginary
flip-flop frequencies. We find that this instability is only effective for mass
ratios $0.5<q<1$. We provide analytic expressions that determine the region of
parameter space for which the instability occurs in terms of maps of the mass
ratio and spin magnitudes $(q,\alpha_1,\alpha_2)$. This restricts the priors of
parameter estimation techniques for the observation of gravitational waves from
binary black holes and it is relevant for astrophysical modeling and final
recoil computations of such binary systems.
| [
{
"created": "Tue, 19 Jan 2016 21:00:00 GMT",
"version": "v1"
}
] | 2016-07-06 | [
[
"Lousto",
"Carlos O.",
""
],
[
"Healy",
"James",
""
]
] | We give a unified description of the flip-flop effect in spinning binary black holes and the anti-alignment instability in terms of real and imaginary flip-flop frequencies. We find that this instability is only effective for mass ratios $0.5<q<1$. We provide analytic expressions that determine the region of parameter space for which the instability occurs in terms of maps of the mass ratio and spin magnitudes $(q,\alpha_1,\alpha_2)$. This restricts the priors of parameter estimation techniques for the observation of gravitational waves from binary black holes and it is relevant for astrophysical modeling and final recoil computations of such binary systems. |
1503.03934 | Tomohiro Harada | Tomohiro Harada, Chul-Moon Yoo, Tomohiro Nakama and Yasutaka Koga | Cosmological long-wavelength solutions and primordial black hole
formation | 33 pages, 4 figures, accepted for publication in Physical Review D | Phys. Rev. D 91, 084057 (2015) | 10.1103/PhysRevD.91.084057 | RUP-15-5, RESCEU-4/15 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct cosmological long-wavelength solutions without symmetry in
general gauge conditions compatible with the long-wavelength scheme. We then
specify the relationship among the solutions in different time slicings.
Applying this general framework to spherical symmetry, we derive the
correspondence relation between long-wavelength solutions in the constant mean
curvature slicing with conformally flat spatial coordinates and asymptotic
quasihomogeneous solutions in the comoving gauge and compare the numerical
results of PBH formation in these two different approaches. To discuss the PBH
formation, it is convenient and conventional to use $\tilde{\delta}_{c}$, the
value which the averaged density perturbation at threshold in the comoving
slicing would take at horizon entry in the lowest-order long-wavelength
expansion. We numerically find that within compensated models, the sharper the
transition from the overdense region to the FRW universe is, the larger the
$\tilde{\delta}_{c}$ becomes. We suggest that, for the equation of state
$p=(\Gamma-1)\rho$, we can apply the analytic formulas for the minimum
$\tilde{\delta}_{c, {\rm min}}\simeq
[3\Gamma/(3\Gamma+2)]\sin^{2}\left[\pi\sqrt{\Gamma-1}/(3\Gamma-2)\right]$ and
the maximum $\tilde{\delta}_{c, {\rm max}}\simeq 3\Gamma/(3\Gamma+2)$. As for
the threshold peak value of the curvature variable $\psi_{0,c}$, we find that
the sharper the transition is, the smaller the $\psi_{0,c}$ becomes. We
analytically explain this feature. Using simplified models, we also
analytically deduce an environmental effect that $\psi_{0,c}$ can be
significantly larger (smaller) if the underlying density perturbation of much
longer wavelength is positive (negative).
| [
{
"created": "Fri, 13 Mar 2015 02:22:27 GMT",
"version": "v1"
},
{
"created": "Mon, 11 May 2015 12:24:13 GMT",
"version": "v2"
}
] | 2018-01-25 | [
[
"Harada",
"Tomohiro",
""
],
[
"Yoo",
"Chul-Moon",
""
],
[
"Nakama",
"Tomohiro",
""
],
[
"Koga",
"Yasutaka",
""
]
] | We construct cosmological long-wavelength solutions without symmetry in general gauge conditions compatible with the long-wavelength scheme. We then specify the relationship among the solutions in different time slicings. Applying this general framework to spherical symmetry, we derive the correspondence relation between long-wavelength solutions in the constant mean curvature slicing with conformally flat spatial coordinates and asymptotic quasihomogeneous solutions in the comoving gauge and compare the numerical results of PBH formation in these two different approaches. To discuss the PBH formation, it is convenient and conventional to use $\tilde{\delta}_{c}$, the value which the averaged density perturbation at threshold in the comoving slicing would take at horizon entry in the lowest-order long-wavelength expansion. We numerically find that within compensated models, the sharper the transition from the overdense region to the FRW universe is, the larger the $\tilde{\delta}_{c}$ becomes. We suggest that, for the equation of state $p=(\Gamma-1)\rho$, we can apply the analytic formulas for the minimum $\tilde{\delta}_{c, {\rm min}}\simeq [3\Gamma/(3\Gamma+2)]\sin^{2}\left[\pi\sqrt{\Gamma-1}/(3\Gamma-2)\right]$ and the maximum $\tilde{\delta}_{c, {\rm max}}\simeq 3\Gamma/(3\Gamma+2)$. As for the threshold peak value of the curvature variable $\psi_{0,c}$, we find that the sharper the transition is, the smaller the $\psi_{0,c}$ becomes. We analytically explain this feature. Using simplified models, we also analytically deduce an environmental effect that $\psi_{0,c}$ can be significantly larger (smaller) if the underlying density perturbation of much longer wavelength is positive (negative). |
2112.00296 | Ujjal Debnath | Ujjal Debnath | Roles of Modified Chaplygin-Jacobi and Chaplygin-Abel Gases in FRW
Universe | 20 pages, 17 figures, Accepted in Int. J. Mod. Phys. A | null | 10.1142/S0217751X21502456 | null | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by/4.0/ | We have considered flat Friedmann-Robertson-Walker (FRW) model of the
universe and reviewed the modified Chaplygin gas as the fluid source.
Associated with the scalar field model, we have determined the Hubble parameter
as a generating function in terms of the scalar field. Instead of hyperbolic
function, we have taken Jacobi elliptic function and Abel function in the
generating function and obtained modified Chaplygin-Jacobi gas (MCJG) and
modified Chaplygin-Abel gas (MCAG) equation of states, respectively. Next, we
have assumed that the universe filled in dark matter, radiation, and dark
energy. The sources of dark energy candidates are assumed as MCJG and MCAG. We
have constrained the model parameters by recent observational data analysis.
Using $\chi^{2}$ minimum test (maximum likelihood estimation), we have
determined the best fit values of the model parameters by OHD+CMB+BAO+SNIa
joint data analysis. To examine the viability of the MCJG and MCAG models, we
have determined the values of the deviations of information criteria like
$\triangle$AIC, $\triangle$BIC and $\triangle$DIC. The evolutions of
cosmological and cosmographical parameters (like equation of state,
deceleration, jerk, snap, lerk, statefinder, Om diagnostic) have been studied
for our best fit values of model parameters. To check the classical stability
of the models, we have examined the values of square speed of sound $v_{s}^{2}$
in the interval $(0,1)$ for expansion of the universe.
| [
{
"created": "Wed, 1 Dec 2021 06:12:04 GMT",
"version": "v1"
}
] | 2021-12-02 | [
[
"Debnath",
"Ujjal",
""
]
] | We have considered flat Friedmann-Robertson-Walker (FRW) model of the universe and reviewed the modified Chaplygin gas as the fluid source. Associated with the scalar field model, we have determined the Hubble parameter as a generating function in terms of the scalar field. Instead of hyperbolic function, we have taken Jacobi elliptic function and Abel function in the generating function and obtained modified Chaplygin-Jacobi gas (MCJG) and modified Chaplygin-Abel gas (MCAG) equation of states, respectively. Next, we have assumed that the universe filled in dark matter, radiation, and dark energy. The sources of dark energy candidates are assumed as MCJG and MCAG. We have constrained the model parameters by recent observational data analysis. Using $\chi^{2}$ minimum test (maximum likelihood estimation), we have determined the best fit values of the model parameters by OHD+CMB+BAO+SNIa joint data analysis. To examine the viability of the MCJG and MCAG models, we have determined the values of the deviations of information criteria like $\triangle$AIC, $\triangle$BIC and $\triangle$DIC. The evolutions of cosmological and cosmographical parameters (like equation of state, deceleration, jerk, snap, lerk, statefinder, Om diagnostic) have been studied for our best fit values of model parameters. To check the classical stability of the models, we have examined the values of square speed of sound $v_{s}^{2}$ in the interval $(0,1)$ for expansion of the universe. |
1004.0091 | Roland Triay | Roland Triay (CPT) | Dark Energy: fiction or reality? | 9 pages, Invited talk at Tenth International Symposium Frontiers of
Fundamental and Computational Physics (FFP10) Perth, Western Australia,
November 24-26, 2009 | AIP Conf.Proc.1246:105-113,2010 | 10.1063/1.3460185 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Is Dark Energy justified as an alternative to the cosmological constant
$\Lambda$ in order to explain the acceleration of the cosmic expansion ? It
turns out that a straightforward dimensional analysis of Einstein equation
provides us with clear evidences that the geometrical nature of $\Lambda$ is
the only viable source to this phenomenon, in addition of the application of
Ockham's razor principle. This contribution is primarily a review of the main
stream in the interpretation of $\Lambda$ because it is at the origin of such a
research program.
| [
{
"created": "Thu, 1 Apr 2010 09:23:36 GMT",
"version": "v1"
}
] | 2014-11-20 | [
[
"Triay",
"Roland",
"",
"CPT"
]
] | Is Dark Energy justified as an alternative to the cosmological constant $\Lambda$ in order to explain the acceleration of the cosmic expansion ? It turns out that a straightforward dimensional analysis of Einstein equation provides us with clear evidences that the geometrical nature of $\Lambda$ is the only viable source to this phenomenon, in addition of the application of Ockham's razor principle. This contribution is primarily a review of the main stream in the interpretation of $\Lambda$ because it is at the origin of such a research program. |
1410.3109 | Alessandro Fabbri | G. Clement and A. Fabbri | An alternative scenario for critical scalar field collapse in $AdS_3$ | 6 pages; Invited talk at ICHEP2014, Valencia July 2014, Parallel
Session `Formal Theory Developments' | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the context of gravitational collapse and black hole formation, we
reconsider the problem to describe analytically the critical collapse of a
massless and minimally coupled scalar field in $2+1$ gravity.
| [
{
"created": "Sun, 12 Oct 2014 16:04:26 GMT",
"version": "v1"
}
] | 2014-10-14 | [
[
"Clement",
"G.",
""
],
[
"Fabbri",
"A.",
""
]
] | In the context of gravitational collapse and black hole formation, we reconsider the problem to describe analytically the critical collapse of a massless and minimally coupled scalar field in $2+1$ gravity. |
0708.3563 | Hrvoje Nikolic | H. Nikolic | Renormalization of vacuum energy in linearized quantum gravity | 5 pages | null | null | null | gr-qc hep-th | null | In linearized quantum gravity, a shift of the average energy-momentum can be
compensated by a shift of the average gravitational field. This allows a
renormalization scheme that naturally removes the contribution of quantum
vacuum fluctuations to the cosmological constant, solving the old
cosmological-constant problem for weak gravitational fields.
| [
{
"created": "Mon, 27 Aug 2007 09:40:47 GMT",
"version": "v1"
}
] | 2007-08-28 | [
[
"Nikolic",
"H.",
""
]
] | In linearized quantum gravity, a shift of the average energy-momentum can be compensated by a shift of the average gravitational field. This allows a renormalization scheme that naturally removes the contribution of quantum vacuum fluctuations to the cosmological constant, solving the old cosmological-constant problem for weak gravitational fields. |
1903.05982 | Matteo Breschi | Matteo Breschi, Richard O'Shaughnessy, Jacob Lange and Ofek Birnholtz | Inspiral-Merger-Ringdown Consistency Tests with Higher Modes on
Gravitational Signals from the Second Observing Run of LIGO and Virgo | null | null | 10.1088/1361-6382/ab5629 | LIGO-P1800365 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Current tests of General Relativity are performed using approximations which
neglect a key feature of complete solution of Einstein's theory: higher-order
modes. Our analysis will reassess these tests, including these higher-order
mode effects. We have chosen to perform inspiral-merger-ringdown consistency
tests on the gravitational transients detected by LIGO and Virgo during the
observing run O2. We use an approximant which includes all higher modes with
$\ell \le 4$ (NRSur7dq2) and then, for the most interesting cases, we repeat
the tests involving fits on Numerical Relativity simulations.
| [
{
"created": "Thu, 14 Mar 2019 13:27:55 GMT",
"version": "v1"
}
] | 2020-01-08 | [
[
"Breschi",
"Matteo",
""
],
[
"O'Shaughnessy",
"Richard",
""
],
[
"Lange",
"Jacob",
""
],
[
"Birnholtz",
"Ofek",
""
]
] | Current tests of General Relativity are performed using approximations which neglect a key feature of complete solution of Einstein's theory: higher-order modes. Our analysis will reassess these tests, including these higher-order mode effects. We have chosen to perform inspiral-merger-ringdown consistency tests on the gravitational transients detected by LIGO and Virgo during the observing run O2. We use an approximant which includes all higher modes with $\ell \le 4$ (NRSur7dq2) and then, for the most interesting cases, we repeat the tests involving fits on Numerical Relativity simulations. |
2007.16186 | Tucker Manton | Damien A. Easson, Cynthia Keeler, Tucker Manton | The classical double copy of non-singular black holes | 42 pages, 15 figures. References added, matches version accepted for
publication in PRD | Phys. Rev. D 102, 086015 (2020) | 10.1103/PhysRevD.102.086015 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We apply the classical double copy procedure to a class of regular,
non-singular black hole solutions. We give several examples, paying particular
attention to a string-theory-corrected black hole solution emerging from
T-duality. Non-perturbative stringy corrections introduce an ultraviolet (UV)
zero-point length cutoff which results in non-singular black hole spacetimes.
Apart from the UV regulator, the solution is equivalent to the Bardeen black
hole spacetime. We extend this solution to include an asymptotic de Sitter
background. All Yang-Mills field theory quantities associated with the double
copy are well-behaved and finite for all values of parameters. We present a
thorough analysis of the black hole horizon structure, additionally uncovering
a simple yet new connection between horizons on the gravity side and electric
fields on the gauge theory side of the double copy.
| [
{
"created": "Fri, 31 Jul 2020 17:28:53 GMT",
"version": "v1"
},
{
"created": "Wed, 16 Sep 2020 16:22:35 GMT",
"version": "v2"
}
] | 2020-10-21 | [
[
"Easson",
"Damien A.",
""
],
[
"Keeler",
"Cynthia",
""
],
[
"Manton",
"Tucker",
""
]
] | We apply the classical double copy procedure to a class of regular, non-singular black hole solutions. We give several examples, paying particular attention to a string-theory-corrected black hole solution emerging from T-duality. Non-perturbative stringy corrections introduce an ultraviolet (UV) zero-point length cutoff which results in non-singular black hole spacetimes. Apart from the UV regulator, the solution is equivalent to the Bardeen black hole spacetime. We extend this solution to include an asymptotic de Sitter background. All Yang-Mills field theory quantities associated with the double copy are well-behaved and finite for all values of parameters. We present a thorough analysis of the black hole horizon structure, additionally uncovering a simple yet new connection between horizons on the gravity side and electric fields on the gauge theory side of the double copy. |
2003.13724 | Vasilis Oikonomou | S.D. Odintsov, V.K. Oikonomou, F.P. Fronimos | Rectifying Einstein-Gauss-Bonnet Inflation in View of GW170817 | NPB Accepted | null | null | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we introduce a new theoretical framework for
Einstein-Gauss-Bonnet theories of gravity, which results to particularly
elegant, functionally simple and transparent gravitational equations of motion,
slow-roll indices and the corresponding observational indices. The main
requirement is that the Einstein-Gauss-Bonnet theory has to be compatible with
the GW170817 event, so the gravitational wave speed $c_T^2$ is required to be
$c_T^2\simeq 1$ in natural units. This assumption was also made in a previous
work of ours, but in this work we express all the related quantities as
functions of the scalar field. The constraint $c_T^2\simeq 1$ restricts the
functional form of the scalar Gauss-Bonnet coupling function $\xi(\phi)$ and of
the scalar potential $V(\phi)$, which must satisfy a differential equation.
However, by also assuming that the slow-roll conditions hold true, the
resulting equations of motion and the slow-roll indices acquire particularly
simple forms, and also the relation that yields the $e$-foldings number is
$N=\int_{\phi_i}^{\phi_f}\xi''/\xi'd \phi$, a fact that enables us to perform
particularly simple calculations in order to study the inflationary
phenomenological implications of several models. As it proves, the models we
presented are compatible with the observational data, and also satisfy all the
assumptions made during the process of extracting the gravitational equations
of motion. More interestingly, we also investigated the phenomenological
implications of an additional condition $\xi'/\xi''\ll 1$, which is motivated
by the slow-roll conditions that are imposed on the scalar field evolution and
on the Hubble rate, in which case the study is easier. Our approach opens a new
window in viable Einstein-Gauss-Bonnet theories of gravity.
| [
{
"created": "Mon, 30 Mar 2020 18:20:42 GMT",
"version": "v1"
},
{
"created": "Sun, 26 Jul 2020 20:12:21 GMT",
"version": "v2"
}
] | 2020-07-28 | [
[
"Odintsov",
"S. D.",
""
],
[
"Oikonomou",
"V. K.",
""
],
[
"Fronimos",
"F. P.",
""
]
] | In this work we introduce a new theoretical framework for Einstein-Gauss-Bonnet theories of gravity, which results to particularly elegant, functionally simple and transparent gravitational equations of motion, slow-roll indices and the corresponding observational indices. The main requirement is that the Einstein-Gauss-Bonnet theory has to be compatible with the GW170817 event, so the gravitational wave speed $c_T^2$ is required to be $c_T^2\simeq 1$ in natural units. This assumption was also made in a previous work of ours, but in this work we express all the related quantities as functions of the scalar field. The constraint $c_T^2\simeq 1$ restricts the functional form of the scalar Gauss-Bonnet coupling function $\xi(\phi)$ and of the scalar potential $V(\phi)$, which must satisfy a differential equation. However, by also assuming that the slow-roll conditions hold true, the resulting equations of motion and the slow-roll indices acquire particularly simple forms, and also the relation that yields the $e$-foldings number is $N=\int_{\phi_i}^{\phi_f}\xi''/\xi'd \phi$, a fact that enables us to perform particularly simple calculations in order to study the inflationary phenomenological implications of several models. As it proves, the models we presented are compatible with the observational data, and also satisfy all the assumptions made during the process of extracting the gravitational equations of motion. More interestingly, we also investigated the phenomenological implications of an additional condition $\xi'/\xi''\ll 1$, which is motivated by the slow-roll conditions that are imposed on the scalar field evolution and on the Hubble rate, in which case the study is easier. Our approach opens a new window in viable Einstein-Gauss-Bonnet theories of gravity. |
2207.10339 | Riasat Ali | Riasat Ali, Rimsha Babar, Muhammad Asgher and Xia Tie-Cheng | Tunneling Analysis of Regular Black Holes with Cosmic Strings-Like
Solution in Newman-Janis Algorithm | 12 pages,7 figures, version accepted for publication in International
Journal of Modern Physics A | null | 10.1142/S0217751X22501081 | null | gr-qc math-ph math.MP | http://creativecommons.org/licenses/by/4.0/ | We consider the regular black holes solution with cosmic strings(RBHCS) in
the rotation parameter by assuming the Newman-Janis method. After this, we
study thermodynamical property (i.e., Hawking temperature $T_H$) for the RBHCS
in the presence of spin parameter. Moreover, we study the graphical
interpretation of Hawking temperature with event horizon to check the physical
and stable form of RBHCS under the effect of Newman-Janis algorithm. We
graphically show that the RBHCS in the context of Newman-Janis algorithm are
colder than the Schwarzschild black hole. Furthermore, we investigate the
quantum corrected temperature for RBHCS in Newman-Janis method by incorporating
generalized uncertainty principle. We have also analyzed the graphical
interpretation of corrected temperature $T'_{H}$ versus $r_{+}$ and study the
stable condition of RBHCS in Newman-Janis method in the presence of gravity
parameter effects. Finally, the corrected entropy for RBHCS with rotation
parameter is analyzed.
| [
{
"created": "Thu, 21 Jul 2022 07:28:45 GMT",
"version": "v1"
}
] | 2022-07-22 | [
[
"Ali",
"Riasat",
""
],
[
"Babar",
"Rimsha",
""
],
[
"Asgher",
"Muhammad",
""
],
[
"Tie-Cheng",
"Xia",
""
]
] | We consider the regular black holes solution with cosmic strings(RBHCS) in the rotation parameter by assuming the Newman-Janis method. After this, we study thermodynamical property (i.e., Hawking temperature $T_H$) for the RBHCS in the presence of spin parameter. Moreover, we study the graphical interpretation of Hawking temperature with event horizon to check the physical and stable form of RBHCS under the effect of Newman-Janis algorithm. We graphically show that the RBHCS in the context of Newman-Janis algorithm are colder than the Schwarzschild black hole. Furthermore, we investigate the quantum corrected temperature for RBHCS in Newman-Janis method by incorporating generalized uncertainty principle. We have also analyzed the graphical interpretation of corrected temperature $T'_{H}$ versus $r_{+}$ and study the stable condition of RBHCS in Newman-Janis method in the presence of gravity parameter effects. Finally, the corrected entropy for RBHCS with rotation parameter is analyzed. |
gr-qc/0201064 | Marcelo Salgado | Marcelo Salgado | Dynamics of spherically symmetric spacetimes: hydrodynamics and
radiation | submitted to Phys. Rev. D, 46 pages, RevTex file, no figures | Phys.Rev.D66:044013,2002 | 10.1103/PhysRevD.66.044013 | null | gr-qc astro-ph | null | Using the 3+1 formalism of general relativity we obtain the equations
governing the dynamics of spherically symmetric spacetimes with arbitrary
sources. We then specialize for the case of perfect fluids accompanied by a
flow of interacting massless or massive particles (e.g. neutrinos) which are
described in terms of relativistic transport theory. We focus in three types of
coordinates: 1) isotropic gauge and maximal slicing, 2) radial gauge and polar
slicing, and 3) isotropic gauge and polar slicing.
| [
{
"created": "Fri, 18 Jan 2002 22:54:52 GMT",
"version": "v1"
}
] | 2010-05-12 | [
[
"Salgado",
"Marcelo",
""
]
] | Using the 3+1 formalism of general relativity we obtain the equations governing the dynamics of spherically symmetric spacetimes with arbitrary sources. We then specialize for the case of perfect fluids accompanied by a flow of interacting massless or massive particles (e.g. neutrinos) which are described in terms of relativistic transport theory. We focus in three types of coordinates: 1) isotropic gauge and maximal slicing, 2) radial gauge and polar slicing, and 3) isotropic gauge and polar slicing. |
2101.03594 | Ozgur Delice | Hatice \"Ozer, \"Ozg\"ur Delice | Gravitational waves in Brans-Dicke Theory with a cosmological constant | V2: 30 pages, Revtex 4-1, References are added, discussion is
extended, section III-D is added, Published version | Eur. Phys. J. C (2021) 81: 326 | 10.1140/epjc/s10052-021-09123-7 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Weak field gravitational wave solutions are investigated in Brans-Dicke (BD)
theory in the presence of a cosmological constant. In this setting the
background geometry is not flat but asymptotically de-Sitter. We investigate
the linearised field equations, and their gravitational wave solutions in a
certain gauge choice. We will show that this theory leads to massless scalar
waves as in original BD theory and in contrast to massive BD theory. The
effects of these waves on free particles and their polarization properties are
studied extensively and effects of the cosmological constant is analyzed in
these phenomena in detail. The energy flux of these waves are also discussed in
this background. By analyzing this flux, we obtain a critical distance where
the waves cannot propagate further, which extends Cosmic no Hair Conjecture
(CNC) to BD theory with a cosmological constant.
| [
{
"created": "Sun, 10 Jan 2021 18:25:36 GMT",
"version": "v1"
},
{
"created": "Tue, 27 Apr 2021 17:57:30 GMT",
"version": "v2"
}
] | 2021-04-28 | [
[
"Özer",
"Hatice",
""
],
[
"Delice",
"Özgür",
""
]
] | Weak field gravitational wave solutions are investigated in Brans-Dicke (BD) theory in the presence of a cosmological constant. In this setting the background geometry is not flat but asymptotically de-Sitter. We investigate the linearised field equations, and their gravitational wave solutions in a certain gauge choice. We will show that this theory leads to massless scalar waves as in original BD theory and in contrast to massive BD theory. The effects of these waves on free particles and their polarization properties are studied extensively and effects of the cosmological constant is analyzed in these phenomena in detail. The energy flux of these waves are also discussed in this background. By analyzing this flux, we obtain a critical distance where the waves cannot propagate further, which extends Cosmic no Hair Conjecture (CNC) to BD theory with a cosmological constant. |
1707.04953 | Vladimir S. Manko | V. S. Manko, E. Ruiz | Simple metric for a magnetized, spinning, deformed mass | 13 pages, 1 figure; minor changes, one reference added | Phys. Rev. D 97, 104016 (2018) | 10.1103/PhysRevD.97.104016 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present and discuss a 4-parameter stationary axisymmetric solution of the
Einstein-Maxwell equations able to describe the exterior field of a rotating
magnetized deformed mass. The solution arises as a system of two overlapping
corotating magnetized non-equal black holes or hyperextreme disks and we write
it in a concise explicit form very suitable for concrete astrophysical
applications. An interesting peculiar feature of this solution is that its
first four electric multipole moments are zeros; it also has a non-trivial
extreme limit which we elaborate completely in terms of four polynomial
factors. We speculate that the formation of the binary configurations of this
type, which is accompanied by a drastic change of the system's total angular
momentum due to strong dragging effects, might be one of the mechanisms giving
birth to relativistic jets in the galactic nuclei.
| [
{
"created": "Sun, 16 Jul 2017 22:11:53 GMT",
"version": "v1"
},
{
"created": "Thu, 20 Jul 2017 06:50:47 GMT",
"version": "v2"
}
] | 2018-05-23 | [
[
"Manko",
"V. S.",
""
],
[
"Ruiz",
"E.",
""
]
] | We present and discuss a 4-parameter stationary axisymmetric solution of the Einstein-Maxwell equations able to describe the exterior field of a rotating magnetized deformed mass. The solution arises as a system of two overlapping corotating magnetized non-equal black holes or hyperextreme disks and we write it in a concise explicit form very suitable for concrete astrophysical applications. An interesting peculiar feature of this solution is that its first four electric multipole moments are zeros; it also has a non-trivial extreme limit which we elaborate completely in terms of four polynomial factors. We speculate that the formation of the binary configurations of this type, which is accompanied by a drastic change of the system's total angular momentum due to strong dragging effects, might be one of the mechanisms giving birth to relativistic jets in the galactic nuclei. |
1503.05405 | Michalis Agathos | Michalis Agathos, Jeroen Meidam, Walter Del Pozzo, Tjonnie G. F. Li,
Marco Tompitak, John Veitch, Salvatore Vitale, Chris Van Den Broeck | Constraining the neutron star equation of state with gravitational wave
signals from coalescing binary neutron stars | 18 pages, 12 figures, revised version accepted for publication in
Phys. Rev. D | Phys. Rev. D 92, 023012 (2015) | 10.1103/PhysRevD.92.023012 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently exploratory studies were performed on the possibility of
constraining the neutron star equation of state (EOS) using signals from
coalescing binary neutron stars, or neutron star-black hole systems, as they
will be seen in upcoming advanced gravitational wave detectors such as Advanced
LIGO and Advanced Virgo. In particular, it was estimated to what extent the
combined information from multiple detections would enable one to distinguish
between different equations of state through hypothesis ranking or parameter
estimation. Under the assumption of zero neutron star spins both in signals and
in template waveforms and considering tidal effects to 1 post-Newtonian (1PN)
order, it was found that O(20) sources would suffice to distinguish between a
hard, moderate, and soft equation of state. Here we revisit these results, this
time including neutron star tidal effects to the highest order currently known,
termination of gravitational waveforms at the contact frequency, neutron star
spins, and the resulting quadrupole-monopole interaction. We also take the
masses of neutron stars in simulated sources to be distributed according to a
relatively strongly peaked Gaussian, as hinted at by observations, but without
assuming that the data analyst will necessarily have accurate knowledge of this
distribution for use as a mass prior. We find that especially the effect of the
latter is dramatic, necessitating many more detections to distinguish between
different EOS and causing systematic biases in parameter estimation, on top of
biases due to imperfect understanding of the signal model pointed out in
earlier work. This would get mitigated if reliable prior information about the
mass distribution could be folded into the analyses.
| [
{
"created": "Wed, 18 Mar 2015 13:39:55 GMT",
"version": "v1"
},
{
"created": "Sun, 12 Jul 2015 14:53:38 GMT",
"version": "v2"
}
] | 2015-08-05 | [
[
"Agathos",
"Michalis",
""
],
[
"Meidam",
"Jeroen",
""
],
[
"Del Pozzo",
"Walter",
""
],
[
"Li",
"Tjonnie G. F.",
""
],
[
"Tompitak",
"Marco",
""
],
[
"Veitch",
"John",
""
],
[
"Vitale",
"Salvatore",
""
],... | Recently exploratory studies were performed on the possibility of constraining the neutron star equation of state (EOS) using signals from coalescing binary neutron stars, or neutron star-black hole systems, as they will be seen in upcoming advanced gravitational wave detectors such as Advanced LIGO and Advanced Virgo. In particular, it was estimated to what extent the combined information from multiple detections would enable one to distinguish between different equations of state through hypothesis ranking or parameter estimation. Under the assumption of zero neutron star spins both in signals and in template waveforms and considering tidal effects to 1 post-Newtonian (1PN) order, it was found that O(20) sources would suffice to distinguish between a hard, moderate, and soft equation of state. Here we revisit these results, this time including neutron star tidal effects to the highest order currently known, termination of gravitational waveforms at the contact frequency, neutron star spins, and the resulting quadrupole-monopole interaction. We also take the masses of neutron stars in simulated sources to be distributed according to a relatively strongly peaked Gaussian, as hinted at by observations, but without assuming that the data analyst will necessarily have accurate knowledge of this distribution for use as a mass prior. We find that especially the effect of the latter is dramatic, necessitating many more detections to distinguish between different EOS and causing systematic biases in parameter estimation, on top of biases due to imperfect understanding of the signal model pointed out in earlier work. This would get mitigated if reliable prior information about the mass distribution could be folded into the analyses. |
1706.07460 | Alexander Zhidenko | K. D. Kokkotas, R. A. Konoplya, A. Zhidenko | An analytical approximation for the Einstein-dilaton-Gauss-Bonnet black
hole metric | 8 pages, 3 figures, 1 ancillary Mathematica(R) notebook; the refereed
version, accepted for publication in Physical Review D | Phys. Rev. D 96, 064004 (2017) | 10.1103/PhysRevD.96.064004 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct an analytical approximation for the numerical black hole metric
of P. Kanti, et. al. [PRD54, 5049 (1996)] in the four-dimensional
Einstein-dilaton-Gauss-Bonnet (EdGB) theory. The continued fraction expansion
in terms of a compactified radial coordinate, used here, converges slowly when
the dilaton coupling approaches its extremal values, but for a black hole far
from the extremal state, the analytical formula has a maximal relative error of
a fraction of one percent already within the third order of the continued
fraction expansion. The suggested analytical representation of the numerical
black hole metric is relatively compact and good approximation in the whole
space outside the black hole event horizon. Therefore, it can serve in the same
way as an exact solution when analyzing particles' motion, perturbations,
quasinormal modes, Hawking radiation, accreting disks and many other problems
in the vicinity of a black hole. In addition, we construct the approximate
analytical expression for the dilaton field.
| [
{
"created": "Thu, 22 Jun 2017 19:00:07 GMT",
"version": "v1"
},
{
"created": "Tue, 8 Aug 2017 23:00:27 GMT",
"version": "v2"
}
] | 2017-09-06 | [
[
"Kokkotas",
"K. D.",
""
],
[
"Konoplya",
"R. A.",
""
],
[
"Zhidenko",
"A.",
""
]
] | We construct an analytical approximation for the numerical black hole metric of P. Kanti, et. al. [PRD54, 5049 (1996)] in the four-dimensional Einstein-dilaton-Gauss-Bonnet (EdGB) theory. The continued fraction expansion in terms of a compactified radial coordinate, used here, converges slowly when the dilaton coupling approaches its extremal values, but for a black hole far from the extremal state, the analytical formula has a maximal relative error of a fraction of one percent already within the third order of the continued fraction expansion. The suggested analytical representation of the numerical black hole metric is relatively compact and good approximation in the whole space outside the black hole event horizon. Therefore, it can serve in the same way as an exact solution when analyzing particles' motion, perturbations, quasinormal modes, Hawking radiation, accreting disks and many other problems in the vicinity of a black hole. In addition, we construct the approximate analytical expression for the dilaton field. |
gr-qc/0602031 | Sunil Maharaj | A. J. John and S. D. Maharaj | An exact isotropic solution | 7 pages, to appear in Il Nuovo Cimento B | Nuovo Cim. B121 (2006) 27-33 | 10.1393/ncb/i2005-10179-y | null | gr-qc | null | The condition for pressure isotropy is reduced to a recurrence equation with
variable, rational coefficients of order three. We prove that this difference
equation can be solved in general. Consequently we can find an exact solution
to the field equations corresponding to a static spherically symmetric
gravitational potential in terms of elementary functions. The metric functions,
the energy density and the pressure are continuous and well behaved which
implies that this solution could be used to model the interior of a
relativistic sphere. The model satisfies a barotropic equation of state in
general which approximates a polytrope close to the stellar centre.
| [
{
"created": "Wed, 8 Feb 2006 13:42:59 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"John",
"A. J.",
""
],
[
"Maharaj",
"S. D.",
""
]
] | The condition for pressure isotropy is reduced to a recurrence equation with variable, rational coefficients of order three. We prove that this difference equation can be solved in general. Consequently we can find an exact solution to the field equations corresponding to a static spherically symmetric gravitational potential in terms of elementary functions. The metric functions, the energy density and the pressure are continuous and well behaved which implies that this solution could be used to model the interior of a relativistic sphere. The model satisfies a barotropic equation of state in general which approximates a polytrope close to the stellar centre. |
gr-qc/0701089 | Chen Songbai | Songbai Chen, Bin Wang, Rukeng Su | Influence of Lorentz violation on Dirac quasinormal modes in the
Schwarzschild black hole spacetime | 10 pages, 4 figure | Class.Quant.Grav.23:7581-7590,2006 | 10.1088/0264-9381/23/24/026 | null | gr-qc | null | Using the third-order WKB approximation and monodromy methods, we investigate
the influence of Lorentz violating coefficient $b$ (associated with a special
axial-vector $b_{\mu}$ field) on Dirac quasinormal modes in the Schwarzschild
black hole spacetime. At fundamental overtone, the real part decreases linearly
as the parameter $b$ increases. But the variation of the imaginary part with
$b$ becomes more complex. For the larger multiple moment $k$, the magnitude of
imaginary part increases with the increase of $b$, which means that presence of
Lorentz violation makes Dirac field damps more rapidly. At high overtones, it
is found that the real part of high-damped quasinormal frequency does not tend
to zero, which is quite a different from the symptotic Dirac quasinormal modes
without Lorentz violation.
| [
{
"created": "Tue, 16 Jan 2007 01:36:27 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Chen",
"Songbai",
""
],
[
"Wang",
"Bin",
""
],
[
"Su",
"Rukeng",
""
]
] | Using the third-order WKB approximation and monodromy methods, we investigate the influence of Lorentz violating coefficient $b$ (associated with a special axial-vector $b_{\mu}$ field) on Dirac quasinormal modes in the Schwarzschild black hole spacetime. At fundamental overtone, the real part decreases linearly as the parameter $b$ increases. But the variation of the imaginary part with $b$ becomes more complex. For the larger multiple moment $k$, the magnitude of imaginary part increases with the increase of $b$, which means that presence of Lorentz violation makes Dirac field damps more rapidly. At high overtones, it is found that the real part of high-damped quasinormal frequency does not tend to zero, which is quite a different from the symptotic Dirac quasinormal modes without Lorentz violation. |
1703.07649 | Sourav Bhattacharya | Sourav Bhattacharya and Theodore N Tomaras | Cosmic structure sizes in generic dark energy models | v2, 19pp; added references and discussions, improved presentation;
accepted in EPJC | Eur. Phys. J. C (2017) 77: 526 | 10.1140/epjc/s10052-017-5102-4 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The maximum allowable size of a spherical cosmic structure as a function of
its mass is determined by the maximum turn around radius $R_{\rm TA,max}$, the
distance from its centre where the attraction on a radial test particle due to
the spherical mass is balanced with the repulsion due to the ambient dark
energy. In this work, we extend the existing results in several directions. (a)
We first show that for $w\neq -1$, the expression for $R_{\rm TA, max}$ found
earlier using the cosmological perturbation theory, can be derived using a
static geometry as well. (b) In the generic dark energy model with arbitrary
time dependent state parameter $w(t)$, taking into account the effect of
inhomogeneities upon the dark energy as well, where it is shown that the data
constrain $w(t={\rm today})>-2.3$, and (c) in the quintessence and the
generalized Chaplygin gas models, both of which are shown to predict structure
sizes consistent with observations.
| [
{
"created": "Tue, 21 Mar 2017 05:47:00 GMT",
"version": "v1"
},
{
"created": "Tue, 25 Jul 2017 04:17:28 GMT",
"version": "v2"
}
] | 2017-08-14 | [
[
"Bhattacharya",
"Sourav",
""
],
[
"Tomaras",
"Theodore N",
""
]
] | The maximum allowable size of a spherical cosmic structure as a function of its mass is determined by the maximum turn around radius $R_{\rm TA,max}$, the distance from its centre where the attraction on a radial test particle due to the spherical mass is balanced with the repulsion due to the ambient dark energy. In this work, we extend the existing results in several directions. (a) We first show that for $w\neq -1$, the expression for $R_{\rm TA, max}$ found earlier using the cosmological perturbation theory, can be derived using a static geometry as well. (b) In the generic dark energy model with arbitrary time dependent state parameter $w(t)$, taking into account the effect of inhomogeneities upon the dark energy as well, where it is shown that the data constrain $w(t={\rm today})>-2.3$, and (c) in the quintessence and the generalized Chaplygin gas models, both of which are shown to predict structure sizes consistent with observations. |
2009.11107 | Raj Patil | Raj Patil | EFT approach to general relativity: correction to EIH Lagrangian due to
electromagnetic charge | null | Gen Relativ Gravit 52, 95 (2020) | 10.1007/s10714-020-02748-1 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We extend the Non-Relativistic formulation of General Relativity (NRGR) given
in Goldberger et al. (Phys Rev D 73:104029, 2006) to incorporate the effects of
electromagnetic charge of the constituents of the binary. We incorporate the
photon field in NRGR by giving the field decomposition and power counting
rules. Using these, we develop the Feynman rules to describe photon and
graviton interactions with point particle worldline. We then find the
corrections to the Einstein-Infeld-Hoffmann Lagrangian (Einstein et al. in Ann
Math 39:65-100, 1938) due to the presence of the photon field and
electromagnetic charge of the constituents of the binary.
| [
{
"created": "Wed, 23 Sep 2020 12:35:56 GMT",
"version": "v1"
}
] | 2020-09-24 | [
[
"Patil",
"Raj",
""
]
] | We extend the Non-Relativistic formulation of General Relativity (NRGR) given in Goldberger et al. (Phys Rev D 73:104029, 2006) to incorporate the effects of electromagnetic charge of the constituents of the binary. We incorporate the photon field in NRGR by giving the field decomposition and power counting rules. Using these, we develop the Feynman rules to describe photon and graviton interactions with point particle worldline. We then find the corrections to the Einstein-Infeld-Hoffmann Lagrangian (Einstein et al. in Ann Math 39:65-100, 1938) due to the presence of the photon field and electromagnetic charge of the constituents of the binary. |
2405.17350 | Jose Socorro Garcia | J. Socorro, J. Juan Rosales and Leonel Toledo-Sesma | Non commutative classical and Quantum fractionary Cosmology: Anisotropic
Bianchi Type I case | 28 pages, 23 figures | null | null | null | gr-qc hep-th | http://creativecommons.org/publicdomain/zero/1.0/ | In this work, we will explore the effects of non-commutativity in fractional
classical and quantum schemes using the anisotropicc Bianchi Type I
cosmological model coupled to a scalar field in the K-essence formalism. We
introduce non-commutative variables considering that all minisuperspace
variables $q^i_{nc}$ do not commute, so the symplectic structure was modified,
resulting in some changes with respect to the traditional formalism. In the
quantum regime, the probability density presents a new structure in the scalar
field corresponding to the value of the non-commutative parameter.
| [
{
"created": "Mon, 27 May 2024 16:54:43 GMT",
"version": "v1"
}
] | 2024-05-28 | [
[
"Socorro",
"J.",
""
],
[
"Rosales",
"J. Juan",
""
],
[
"Toledo-Sesma",
"Leonel",
""
]
] | In this work, we will explore the effects of non-commutativity in fractional classical and quantum schemes using the anisotropicc Bianchi Type I cosmological model coupled to a scalar field in the K-essence formalism. We introduce non-commutative variables considering that all minisuperspace variables $q^i_{nc}$ do not commute, so the symplectic structure was modified, resulting in some changes with respect to the traditional formalism. In the quantum regime, the probability density presents a new structure in the scalar field corresponding to the value of the non-commutative parameter. |
1910.08544 | Diego Blas | Diego Blas, Diana L\'opez Nacir, Sergey Sibiryakov | Secular effects of Ultralight Dark Matter on Binary Pulsars | 24 pages, 3 figures, 3 tables; in v2 we introduced new
clarifications, updated fig. 3 to include current bounds and agrees with the
published version | Phys. Rev. D 101, 063016 (2020) | 10.1103/PhysRevD.101.063016 | CERN-TH-2019-165, INR-TH-2019-018, KCL-PH-TH/2019-77 | gr-qc astro-ph.HE hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Dark matter (DM) can consist of very light bosons behaving as a classical
scalar field that experiences coherent oscillations. The presence of this DM
field would perturb the dynamics of celestial bodies, either because the
(oscillating) DM stress tensor modifies the gravitational potentials of the
galaxy, or if DM is directly coupled to the constituents of the body. We study
secular variations of the orbital parameters of binary systems induced by such
perturbations. Two classes of effects are identified. Effects of the first
class appear if the frequency of DM oscillations is in resonance with the
orbital motion; these exist for general DM couplings including the case of
purely gravitational interaction. Effects of the second class arise if DM is
coupled quadratically to the masses of the binary system members and do not
require any resonant condition. The exquisite precision of binary pulsar timing
can be used to constrain these effects. Current observations are not sensitive
to oscillations in the galactic gravitational field, though a discovery of
pulsars in regions of high DM density may improve the situation. For DM with
direct coupling to ordinary matter, the current timing data are already
competitive with other existing constraints in the range of DM masses $\sim
10^{-22}-10^{-18}\,{\rm eV}$. Future observations are expected to increase the
sensitivity and probe new regions of parameters.
| [
{
"created": "Fri, 18 Oct 2019 10:02:54 GMT",
"version": "v1"
},
{
"created": "Wed, 26 Feb 2020 18:56:19 GMT",
"version": "v2"
}
] | 2020-03-18 | [
[
"Blas",
"Diego",
""
],
[
"Nacir",
"Diana López",
""
],
[
"Sibiryakov",
"Sergey",
""
]
] | Dark matter (DM) can consist of very light bosons behaving as a classical scalar field that experiences coherent oscillations. The presence of this DM field would perturb the dynamics of celestial bodies, either because the (oscillating) DM stress tensor modifies the gravitational potentials of the galaxy, or if DM is directly coupled to the constituents of the body. We study secular variations of the orbital parameters of binary systems induced by such perturbations. Two classes of effects are identified. Effects of the first class appear if the frequency of DM oscillations is in resonance with the orbital motion; these exist for general DM couplings including the case of purely gravitational interaction. Effects of the second class arise if DM is coupled quadratically to the masses of the binary system members and do not require any resonant condition. The exquisite precision of binary pulsar timing can be used to constrain these effects. Current observations are not sensitive to oscillations in the galactic gravitational field, though a discovery of pulsars in regions of high DM density may improve the situation. For DM with direct coupling to ordinary matter, the current timing data are already competitive with other existing constraints in the range of DM masses $\sim 10^{-22}-10^{-18}\,{\rm eV}$. Future observations are expected to increase the sensitivity and probe new regions of parameters. |
1711.00605 | Marcony Silva Cunha | V. B. Bezerra, H. R. Christiansen, M. S. Cunha, C. R. Muniz, M. O.
Tahim | Thermal Casimir effect in Kerr spacetime with quintessence and massive
gravitons | 15 pages, 4 figures | Eur.Phys.J. C77 (2017) no.11, 787 | 10.1140/epjc/s10052-017-5378-4 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Starting from an analytical expression for the Helmholtz free energy we
calculate the thermal corrections to the Casimir energy-density and entropy
within nearby ideal parallel plates in the vacuum of a massless scalar field.
Our framework is the Kerr spacetime in the presence of quintessence and massive
gravitons. The high and low temperature regimes are especially analysed in
order to distinguish the main contributions. For instance, in the high
temperature regime, we show that the force between the plates is repulsive and
grows with both the quintessence and the massive gravitons. Regarding the
Casimir entropy, our results are in agreement with the Nernst heat theorem and
therefore confirm the third law of thermodynamics in the present scenario.
| [
{
"created": "Thu, 2 Nov 2017 03:19:21 GMT",
"version": "v1"
}
] | 2017-11-23 | [
[
"Bezerra",
"V. B.",
""
],
[
"Christiansen",
"H. R.",
""
],
[
"Cunha",
"M. S.",
""
],
[
"Muniz",
"C. R.",
""
],
[
"Tahim",
"M. O.",
""
]
] | Starting from an analytical expression for the Helmholtz free energy we calculate the thermal corrections to the Casimir energy-density and entropy within nearby ideal parallel plates in the vacuum of a massless scalar field. Our framework is the Kerr spacetime in the presence of quintessence and massive gravitons. The high and low temperature regimes are especially analysed in order to distinguish the main contributions. For instance, in the high temperature regime, we show that the force between the plates is repulsive and grows with both the quintessence and the massive gravitons. Regarding the Casimir entropy, our results are in agreement with the Nernst heat theorem and therefore confirm the third law of thermodynamics in the present scenario. |
0711.3575 | Kenta Kiuchi | Kenta Kiuchi and Hisa-aki Shinkai | Numerical experiments of adjusted BSSN systems for controlling
constraint violations | to be published in PRD | Phys.Rev.D77:044010,2008 | 10.1103/PhysRevD.77.044010 | null | gr-qc astro-ph | null | We present our numerical comparisons between the BSSN formulation widely used
in numerical relativity today and its adjusted versions using constraints. We
performed three testbeds: gauge-wave, linear wave, and Gowdy-wave tests,
proposed by the Mexico workshop on the formulation problem of the Einstein
equations. We tried three kinds of adjustments, which were previously proposed
from the analysis of the constraint propagation equations, and investigated how
they improve the accuracy and stability of evolutions. We observed that the
signature of the proposed Lagrange multipliers are always right and the
adjustments improve the convergence and stability of the simulations. When the
original BSSN system already shows satisfactory good evolutions (e.g., linear
wave test), the adjusted versions also coincide with those evolutions; while in
some cases (e.g., gauge-wave or Gowdy-wave tests) the simulations using the
adjusted systems last 10 times as long as those using the original BSSN
equations. Our demonstrations imply a potential to construct a robust evolution
system against constraint violations even in highly dynamical situations.
| [
{
"created": "Thu, 22 Nov 2007 14:01:24 GMT",
"version": "v1"
},
{
"created": "Mon, 7 Jan 2008 11:01:02 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Kiuchi",
"Kenta",
""
],
[
"Shinkai",
"Hisa-aki",
""
]
] | We present our numerical comparisons between the BSSN formulation widely used in numerical relativity today and its adjusted versions using constraints. We performed three testbeds: gauge-wave, linear wave, and Gowdy-wave tests, proposed by the Mexico workshop on the formulation problem of the Einstein equations. We tried three kinds of adjustments, which were previously proposed from the analysis of the constraint propagation equations, and investigated how they improve the accuracy and stability of evolutions. We observed that the signature of the proposed Lagrange multipliers are always right and the adjustments improve the convergence and stability of the simulations. When the original BSSN system already shows satisfactory good evolutions (e.g., linear wave test), the adjusted versions also coincide with those evolutions; while in some cases (e.g., gauge-wave or Gowdy-wave tests) the simulations using the adjusted systems last 10 times as long as those using the original BSSN equations. Our demonstrations imply a potential to construct a robust evolution system against constraint violations even in highly dynamical situations. |
2201.03381 | Yu-Xiao Liu | Si-Jiang Yang, Yu-Peng Zhang, Shao-Wen Wei, Yu-Xiao Liu | Destroying the event horizon of a nonsingular rotating quantum-corrected
black hole | 19 pages, 1 figure, published version | JHEP 04 (2022) 066 | 10.1007/JHEP04(2022)066 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The destruction of the event horizon of a nonsingular black hole, which is
not prevented by the weak cosmic censorship conjecture, might provide us the
possibility to access quantum regime of gravity inside black hole. We
investigate the possibility of overspinning a nonsingular rotating
quantum-corrected black hole by a test particle and a scalar field in this
paper, and analyse the effect of the quantum parameter on the destruction of
the event horizon. For the test particle injection, both extremal and
near-extremal black holes cannot be overspun due to the existence of the
quantum parameter. And the larger the quantum parameter the harder the black
hole to be overspun. It seems that the quantum parameter acts as a protector to
prevent the black hole to be destroyed. However, for the test scalar field
scattering, both extremal and near-extremal black holes can be destroyed. Due
to the loop quantum gravity correction, the angular velocity of the extremal
black hole shifts from that of the extremal Kerr black hole. This provides a
small range of wave modes to destroy the event horizon of the quantum-corrected
black hole.
| [
{
"created": "Mon, 10 Jan 2022 15:03:08 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Apr 2022 12:39:33 GMT",
"version": "v2"
}
] | 2022-04-21 | [
[
"Yang",
"Si-Jiang",
""
],
[
"Zhang",
"Yu-Peng",
""
],
[
"Wei",
"Shao-Wen",
""
],
[
"Liu",
"Yu-Xiao",
""
]
] | The destruction of the event horizon of a nonsingular black hole, which is not prevented by the weak cosmic censorship conjecture, might provide us the possibility to access quantum regime of gravity inside black hole. We investigate the possibility of overspinning a nonsingular rotating quantum-corrected black hole by a test particle and a scalar field in this paper, and analyse the effect of the quantum parameter on the destruction of the event horizon. For the test particle injection, both extremal and near-extremal black holes cannot be overspun due to the existence of the quantum parameter. And the larger the quantum parameter the harder the black hole to be overspun. It seems that the quantum parameter acts as a protector to prevent the black hole to be destroyed. However, for the test scalar field scattering, both extremal and near-extremal black holes can be destroyed. Due to the loop quantum gravity correction, the angular velocity of the extremal black hole shifts from that of the extremal Kerr black hole. This provides a small range of wave modes to destroy the event horizon of the quantum-corrected black hole. |
2310.11072 | Karim Thebault | Nick Huggett and Karim P. Y. Th\'ebault | Finding Time for Wheeler-DeWitt Cosmology | null | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We conduct a case study analysis of a proposal for the emergence of time
based upon the approximate derivation of three grades of temporal structure
within an explicit quantum cosmological model which obeys a Wheeler-DeWitt type
equation without an extrinsic time parameter. Our main focus will be issues
regarding the consistency of the approximations and derivations in question.
Our conclusion is that the model provides a self-consistent account of the
emergence of chronordinal, chronometric and chronodirected structure. Residual
concerns relate to explanatory rather than consistency considerations.
| [
{
"created": "Tue, 17 Oct 2023 08:38:40 GMT",
"version": "v1"
}
] | 2023-10-18 | [
[
"Huggett",
"Nick",
""
],
[
"Thébault",
"Karim P. Y.",
""
]
] | We conduct a case study analysis of a proposal for the emergence of time based upon the approximate derivation of three grades of temporal structure within an explicit quantum cosmological model which obeys a Wheeler-DeWitt type equation without an extrinsic time parameter. Our main focus will be issues regarding the consistency of the approximations and derivations in question. Our conclusion is that the model provides a self-consistent account of the emergence of chronordinal, chronometric and chronodirected structure. Residual concerns relate to explanatory rather than consistency considerations. |
gr-qc/0610118 | Francisco Lobo | Francisco S. N. Lobo | Van der Waals quintessence stars | 8 pages, 1 figure, Revtex4. V2: clarifying comments and references
added, now 9 pages | Phys.Rev.D75:024023,2007 | 10.1103/PhysRevD.75.024023 | null | gr-qc astro-ph hep-th | null | The van der Waals quintessence equation of state is an interesting scenario
for describing the late universe, and seems to provide a solution to the puzzle
of dark energy, without the presence of exotic fluids or modifications of the
Friedmann equations. In this work, the construction of inhomogeneous compact
spheres supported by a van der Waals equation of state is explored. These
relativistic stellar configurations shall be denoted as {\it van der Waals
quintessence stars}. Despite of the fact that, in a cosmological context, the
van der Waals fluid is considered homogeneous, inhomogeneities may arise
through gravitational instabilities. Thus, these solutions may possibly
originate from density fluctuations in the cosmological background. Two
specific classes of solutions, namely, gravastars and traversable wormholes are
analyzed. Exact solutions are found, and their respective characteristics and
physical properties are further explored.
| [
{
"created": "Wed, 25 Oct 2006 13:28:53 GMT",
"version": "v1"
},
{
"created": "Fri, 19 Jan 2007 19:31:03 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Lobo",
"Francisco S. N.",
""
]
] | The van der Waals quintessence equation of state is an interesting scenario for describing the late universe, and seems to provide a solution to the puzzle of dark energy, without the presence of exotic fluids or modifications of the Friedmann equations. In this work, the construction of inhomogeneous compact spheres supported by a van der Waals equation of state is explored. These relativistic stellar configurations shall be denoted as {\it van der Waals quintessence stars}. Despite of the fact that, in a cosmological context, the van der Waals fluid is considered homogeneous, inhomogeneities may arise through gravitational instabilities. Thus, these solutions may possibly originate from density fluctuations in the cosmological background. Two specific classes of solutions, namely, gravastars and traversable wormholes are analyzed. Exact solutions are found, and their respective characteristics and physical properties are further explored. |
gr-qc/0609097 | Lorenzo Iorio | Lorenzo Iorio | A comment on the paper "On the orbit of the LARES satellite", by I.
Ciufolini | LaTex, 7 pages, no figures, 1 table. It refers to gr-qc/0609081 by I.
Ciufolini. Quotation from such paper added: in it Ciufolini explicitly claims
that his nearly polar LARES would be sufficient, without using LAGEOS and
LAGEOS II. Typos corrected. Reference added. Style improved. Clarifications
added. To appear in Planetary and Space Science | Planet.SpaceSci.55:1198-1200,2007 | 10.1016/j.pss.2007.03.005 | null | gr-qc astro-ph physics.geo-ph physics.space-ph | null | In this note we comment on a recent paper by I.Ciufolini about the
possibility of placing the proposed terrestrial satellite LARES in a
low-altitude, nearly polar orbit in order to measure the general relativistic
Lense-Thirring effect with its node. Ciufolini claims that, for a departure of
4 deg in the satellite's inclination $i$ from the ideal polar configuration
(i=90 deg), the impact of the errors in the even zonal harmonics of the
geopotential, modelled with EIGEN-GRACE02S, would be nearly zero allowing for a
few-percent measurement of the Lense-Thirring effect. Instead, we find that,
with the same Earth gravity model and for the same values of the inclination,
the upper bound of the systematic error due to the mismodelling in the even
zonals amounts to 64% of the relativistic effect investigated.
| [
{
"created": "Thu, 21 Sep 2006 23:35:34 GMT",
"version": "v1"
},
{
"created": "Mon, 20 Nov 2006 19:09:50 GMT",
"version": "v2"
},
{
"created": "Thu, 23 Nov 2006 18:09:09 GMT",
"version": "v3"
},
{
"created": "Thu, 22 Feb 2007 00:35:00 GMT",
"version": "v4"
},
{
"c... | 2008-11-26 | [
[
"Iorio",
"Lorenzo",
""
]
] | In this note we comment on a recent paper by I.Ciufolini about the possibility of placing the proposed terrestrial satellite LARES in a low-altitude, nearly polar orbit in order to measure the general relativistic Lense-Thirring effect with its node. Ciufolini claims that, for a departure of 4 deg in the satellite's inclination $i$ from the ideal polar configuration (i=90 deg), the impact of the errors in the even zonal harmonics of the geopotential, modelled with EIGEN-GRACE02S, would be nearly zero allowing for a few-percent measurement of the Lense-Thirring effect. Instead, we find that, with the same Earth gravity model and for the same values of the inclination, the upper bound of the systematic error due to the mismodelling in the even zonals amounts to 64% of the relativistic effect investigated. |
2008.05019 | Matthew Duez | Matthew D. Duez, Alexander Knight, Francois Foucart, Milad Haddadi,
Jerred Jesse, Francois Hebert, Lawrence E. Kidder, Harald P. Pfeiffer, and
Mark A. Scheel | A comparison of momentum transport models for numerical relativity | 15 pagers, 11 figures | Phys. Rev. D 102, 104050 (2020) | 10.1103/PhysRevD.102.104050 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The main problems of nonvacuum numerical relativity, compact binary mergers
and stellar collapse, involve hydromagnetic instabilities and turbulent flows,
so that kinetic energy at small scales have mean effects at large scale that
drive the secular evolution. Notable among these effects is momentum transport.
We investigate two models of this transport effect, a relativistic
Navier-Stokes system and a turbulent mean stress model, that are similar to all
of the prescriptions that have been attempted to date for treating subgrid
effects on binary neutron star mergers and their aftermath. Our investigation
involves both stability analysis and numerical experimentation on star and disk
systems. We also begin the investigation of the effects of particle and heat
transport on post-merger simulations. We find that correct handling of
turbulent heating can be important for avoiding unphysical instabilities. Given
such appropriate handling, the evolution of a differentially rotating star and
the accretion rate of a disk are reassuringly insensitive to the choice of
prescription. However, disk outflows can be sensitive to the choice of method,
even for the same effective viscous strength. We also consider the effects of
eddy diffusion in the evolution of an accretion disk and show that it can
interestingly affect the composition of outflows.
| [
{
"created": "Tue, 11 Aug 2020 22:23:25 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Dec 2020 18:56:19 GMT",
"version": "v2"
}
] | 2020-12-15 | [
[
"Duez",
"Matthew D.",
""
],
[
"Knight",
"Alexander",
""
],
[
"Foucart",
"Francois",
""
],
[
"Haddadi",
"Milad",
""
],
[
"Jesse",
"Jerred",
""
],
[
"Hebert",
"Francois",
""
],
[
"Kidder",
"Lawrence E.",
""
... | The main problems of nonvacuum numerical relativity, compact binary mergers and stellar collapse, involve hydromagnetic instabilities and turbulent flows, so that kinetic energy at small scales have mean effects at large scale that drive the secular evolution. Notable among these effects is momentum transport. We investigate two models of this transport effect, a relativistic Navier-Stokes system and a turbulent mean stress model, that are similar to all of the prescriptions that have been attempted to date for treating subgrid effects on binary neutron star mergers and their aftermath. Our investigation involves both stability analysis and numerical experimentation on star and disk systems. We also begin the investigation of the effects of particle and heat transport on post-merger simulations. We find that correct handling of turbulent heating can be important for avoiding unphysical instabilities. Given such appropriate handling, the evolution of a differentially rotating star and the accretion rate of a disk are reassuringly insensitive to the choice of prescription. However, disk outflows can be sensitive to the choice of method, even for the same effective viscous strength. We also consider the effects of eddy diffusion in the evolution of an accretion disk and show that it can interestingly affect the composition of outflows. |
1208.0025 | Davood Momeni Dr | Mubasher Jamil, D. Momeni, Ratbay Myrzakulov | Stability of a non-minimally conformally coupled scalar field in F(T)
cosmology | 12 pages, 9 figures, 1 table | Eur. Phys. J. C (2012) 72:2075 | 10.1140/epjc/s10052-012-2075-1 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we introduce a non-minimally conformally coupled scalar field
and dark matter in F(T) cosmology and study their dynamics. We investigate the
stability and phase space behavior of the parameters of the scalar field by
choosing an exponential potential and cosmologically viable form of F(T). We
found that the dynamical system of equations admits two unstable critical
points; thus no attractor solutions exist in this cosmology. Furthermore,
taking into account the scalar field mimicking quintessence and phantom energy,
we discuss the corresponding cosmic evolution for both small and large times.
We investigate the cosmological implications of the model via the equation of
state and deceleration parameters of our model and show that the late-time
Universe will be dominated by phantom energy and, moreover, phantom crossing is
possible. Our results do not lead to explicit predictions for inflation and the
early Universe era.
| [
{
"created": "Mon, 30 Jul 2012 03:57:15 GMT",
"version": "v1"
}
] | 2012-08-02 | [
[
"Jamil",
"Mubasher",
""
],
[
"Momeni",
"D.",
""
],
[
"Myrzakulov",
"Ratbay",
""
]
] | In this paper, we introduce a non-minimally conformally coupled scalar field and dark matter in F(T) cosmology and study their dynamics. We investigate the stability and phase space behavior of the parameters of the scalar field by choosing an exponential potential and cosmologically viable form of F(T). We found that the dynamical system of equations admits two unstable critical points; thus no attractor solutions exist in this cosmology. Furthermore, taking into account the scalar field mimicking quintessence and phantom energy, we discuss the corresponding cosmic evolution for both small and large times. We investigate the cosmological implications of the model via the equation of state and deceleration parameters of our model and show that the late-time Universe will be dominated by phantom energy and, moreover, phantom crossing is possible. Our results do not lead to explicit predictions for inflation and the early Universe era. |
2112.13855 | Yusuke Manita | Yusuke Manita and Rampei Kimura | Linear growth of structure in projected massive gravity | 16 pages, 5 figures. v2: typos corrected | null | 10.1103/PhysRevD.105.084038 | KUNS-2911 | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | In the present paper, we investigate the linear growth of matter fluctuations
based on a concrete model of the projected massive gravity, which is free of
the Boulware-Deser ghost and preserves the global Lorentz symmetry. We found
that at subhorizon scales, the modification to the linear growth is strongly
suppressed even without nonlinear screening of an additional force. In
addition, we obtain observational constraints from distance and redshift space
distortion measurements and find that there is a parameter region that is
consistent both observationally and theoretically.
| [
{
"created": "Mon, 27 Dec 2021 19:00:03 GMT",
"version": "v1"
},
{
"created": "Sun, 5 Jun 2022 10:14:02 GMT",
"version": "v2"
}
] | 2022-06-07 | [
[
"Manita",
"Yusuke",
""
],
[
"Kimura",
"Rampei",
""
]
] | In the present paper, we investigate the linear growth of matter fluctuations based on a concrete model of the projected massive gravity, which is free of the Boulware-Deser ghost and preserves the global Lorentz symmetry. We found that at subhorizon scales, the modification to the linear growth is strongly suppressed even without nonlinear screening of an additional force. In addition, we obtain observational constraints from distance and redshift space distortion measurements and find that there is a parameter region that is consistent both observationally and theoretically. |
1612.05999 | Zbigniew Haba | Z. Haba | Thermodynamics of diffusive DM/DE systems | 20 pages | Gen.Relativ.Gravit (2017) 49:58 | 10.1007/s10714-017-2224-9 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss the energy density,temperature and entropy of dark matter (DM) and
dark energy (DE) as functions of the scale factor $a$ in an expanding universe.
In a model of non-interacting dark components we repeat a derivation from
thermodynamics of the well-known relations between the energy density,entropy
and temperature. In particular, the entropy is constant as a consequence of the
energy conservation. We consider a model of the DM/DE interaction where DM
energy density increase is proportional to the particle density. In such a
model the dependence of the energy density and the temperature on the scale
factor $a$ is substantially modified. We discuss (as a realization of the
model) DM which consists of relativistic particles diffusing in an environment
of DE. The energy gained by the dark matter comes from a cosmological fluid
with a negative pressure. We define the entropy and free energy of such a
non-equilibrium system. We show that during the universe evolution the entropy
of DM is increasing whereas the entropy of DE is decreasing. The total entropy
can increase (in spite of the energy conservation) as DM and DE temperatures
are different. We discuss non-equilibrium thermodynamics on the basis of the
notion of relative entropy.
| [
{
"created": "Sun, 18 Dec 2016 21:49:54 GMT",
"version": "v1"
},
{
"created": "Thu, 23 Mar 2017 13:07:31 GMT",
"version": "v2"
}
] | 2017-03-27 | [
[
"Haba",
"Z.",
""
]
] | We discuss the energy density,temperature and entropy of dark matter (DM) and dark energy (DE) as functions of the scale factor $a$ in an expanding universe. In a model of non-interacting dark components we repeat a derivation from thermodynamics of the well-known relations between the energy density,entropy and temperature. In particular, the entropy is constant as a consequence of the energy conservation. We consider a model of the DM/DE interaction where DM energy density increase is proportional to the particle density. In such a model the dependence of the energy density and the temperature on the scale factor $a$ is substantially modified. We discuss (as a realization of the model) DM which consists of relativistic particles diffusing in an environment of DE. The energy gained by the dark matter comes from a cosmological fluid with a negative pressure. We define the entropy and free energy of such a non-equilibrium system. We show that during the universe evolution the entropy of DM is increasing whereas the entropy of DE is decreasing. The total entropy can increase (in spite of the energy conservation) as DM and DE temperatures are different. We discuss non-equilibrium thermodynamics on the basis of the notion of relative entropy. |
2111.13883 | Zhi-Chao Zhao | Zhi-Chao Zhao and Zhoujian Cao | Stochastic gravitational wave background due to gravitational wave
memory | 21 pages, 3 figures | null | 10.1007/s11433-022-1965-y | null | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | Gravitational wave memory is an important prediction of general relativity,
which has not been detected yet. Amounts of memory events can form a stochastic
gravitational wave memory background. Here we find that memory background can
be described as a Brownian motion in the condition that the observation time is
longer than the averaged time interval between two successive memory events. We
investigate, for the first time, the memory background of binary black hole
coalescences. We only consider the spectrum of the memory background for a
relatively low frequency range. So we can use the step function to approximate
the waveform for each memory event. Then we find that the spectrum is a power
law with index -2. And the amplitude of the power law spectrum depends on and
only on the merger rate of the binary black holes. Consequently, the memory
background not only provides a brand new means to detect gravitational wave
memory but also opens a new window to explore the event rate of binary black
hole mergers and the gravity theory. Space-based detectors are ideal to detect
the gravitational wave memory background which corresponds to supermassive
binary black holes. Since gravitational wave memory is only sensitive to the
merger stage of binary black hole coalescence, the memory background will be an
ideal probe of the famous final parsec problem.
| [
{
"created": "Sat, 27 Nov 2021 12:41:13 GMT",
"version": "v1"
},
{
"created": "Fri, 10 Dec 2021 13:33:37 GMT",
"version": "v2"
},
{
"created": "Fri, 9 Dec 2022 16:28:29 GMT",
"version": "v3"
}
] | 2022-12-12 | [
[
"Zhao",
"Zhi-Chao",
""
],
[
"Cao",
"Zhoujian",
""
]
] | Gravitational wave memory is an important prediction of general relativity, which has not been detected yet. Amounts of memory events can form a stochastic gravitational wave memory background. Here we find that memory background can be described as a Brownian motion in the condition that the observation time is longer than the averaged time interval between two successive memory events. We investigate, for the first time, the memory background of binary black hole coalescences. We only consider the spectrum of the memory background for a relatively low frequency range. So we can use the step function to approximate the waveform for each memory event. Then we find that the spectrum is a power law with index -2. And the amplitude of the power law spectrum depends on and only on the merger rate of the binary black holes. Consequently, the memory background not only provides a brand new means to detect gravitational wave memory but also opens a new window to explore the event rate of binary black hole mergers and the gravity theory. Space-based detectors are ideal to detect the gravitational wave memory background which corresponds to supermassive binary black holes. Since gravitational wave memory is only sensitive to the merger stage of binary black hole coalescence, the memory background will be an ideal probe of the famous final parsec problem. |
1305.5831 | Ehoud Pazy | Ehoud Pazy | Considerations for a cosmological extension of modified Newtonian
dynamics connections to conformal gravity and Rindler force theories | 23 pages, No figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Modified Newtonian dynamics (MOND) can be obtained by modifying the entropic
formulation of gravity, this is achieved by considering the quantum statistical
nature of the degrees of freedom on the holographic screen. Through this frame
work, we find some constraints on a cosmological extension for MOND, with no
additional auxiliary fields. The connections between MOND to conformal gravity
and Rindler force gravity are examined. These two alternative gravity theories
are subsequently considered as possible cosmological extensions of MOND.
| [
{
"created": "Fri, 24 May 2013 19:19:33 GMT",
"version": "v1"
}
] | 2013-05-27 | [
[
"Pazy",
"Ehoud",
""
]
] | Modified Newtonian dynamics (MOND) can be obtained by modifying the entropic formulation of gravity, this is achieved by considering the quantum statistical nature of the degrees of freedom on the holographic screen. Through this frame work, we find some constraints on a cosmological extension for MOND, with no additional auxiliary fields. The connections between MOND to conformal gravity and Rindler force gravity are examined. These two alternative gravity theories are subsequently considered as possible cosmological extensions of MOND. |
2209.11317 | Anthony Brady PhD | Anthony J. Brady, Ivan Agullo, Dimitrios Kranas | Symplectic circuits, entanglement, and stimulated Hawking radiation in
analog gravity | 25 + 10 pages and 21 figures. Comments welcome | null | 10.1103/PhysRevD.106.105021 | null | gr-qc cond-mat.stat-mech quant-ph | http://creativecommons.org/licenses/by/4.0/ | We introduce a convenient set of analytical tools (the Gaussian formalism)
and diagrams (symplectic circuits) to analyze multi-mode scattering events in
analog gravity, such as pair-creation a l\'a Hawking by black hole and white
hole analog event horizons. The diagrams prove to be valuable ansatzes for the
scattering dynamics, especially in settings where direct analytic results are
not straightforward and one must instead rely on numerical simulations. We use
these tools to investigate entanglement generation in single- and multi-horizon
scenarios, in particular when the Hawking process is stimulated with classical
(e.g., thermal noise) and non-classical (e.g., single-mode squeezed vacuum)
input states -- demonstrating, for instance, that initial squeezing can enhance
the production of entanglement and overcome the deleterious effects that
initial thermal fluctuations have on the output entanglement. To make further
contact with practical matters, we examine how attenuation degrades quantum
correlations between Hawking pairs. The techniques that we employ are generally
applicable to analog gravity setups of (Gaussian) bosonic quantum systems, such
as analog horizons produced in optical analogs and in Bose-Einstein
condensates, and should be of great utility in these domains. We show the
applicability of these techniques by putting them in action for an optical
system containing a pair white-black hole analog, extending our previous
analysis of [Phys. Rev. Lett. 128, 091301 (2022)].
| [
{
"created": "Thu, 22 Sep 2022 21:16:17 GMT",
"version": "v1"
}
] | 2022-12-14 | [
[
"Brady",
"Anthony J.",
""
],
[
"Agullo",
"Ivan",
""
],
[
"Kranas",
"Dimitrios",
""
]
] | We introduce a convenient set of analytical tools (the Gaussian formalism) and diagrams (symplectic circuits) to analyze multi-mode scattering events in analog gravity, such as pair-creation a l\'a Hawking by black hole and white hole analog event horizons. The diagrams prove to be valuable ansatzes for the scattering dynamics, especially in settings where direct analytic results are not straightforward and one must instead rely on numerical simulations. We use these tools to investigate entanglement generation in single- and multi-horizon scenarios, in particular when the Hawking process is stimulated with classical (e.g., thermal noise) and non-classical (e.g., single-mode squeezed vacuum) input states -- demonstrating, for instance, that initial squeezing can enhance the production of entanglement and overcome the deleterious effects that initial thermal fluctuations have on the output entanglement. To make further contact with practical matters, we examine how attenuation degrades quantum correlations between Hawking pairs. The techniques that we employ are generally applicable to analog gravity setups of (Gaussian) bosonic quantum systems, such as analog horizons produced in optical analogs and in Bose-Einstein condensates, and should be of great utility in these domains. We show the applicability of these techniques by putting them in action for an optical system containing a pair white-black hole analog, extending our previous analysis of [Phys. Rev. Lett. 128, 091301 (2022)]. |
1904.03129 | Shao-Wen Wei | Shao-Wen Wei, Jie Yang, Yu-Xiao Liu | Geodesics and periodic orbits in Kehagias-Sfetsos black holes in
deformed Ho\u{r}ava-Lifshitz gravity | 12 pages, 8 figures, and 2 tables, accepted by PRD | Phys. Rev. D 99, 104016 (2019) | 10.1103/PhysRevD.99.104016 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The motion of a massive test particle around a Kehagias-Sfetsos black hole in
deformed Ho\u{r}ava-Lifshitz gravity is studied. Employing the effective
potential, the marginally bound orbits and the innermost stable circular orbits
are analyzed. For the marginally bound orbits, their radius and angular
momentum decrease with the parameter $\omega$ of the gravity. For the innermost
stable circular orbits, the energy and angular momentum also decrease with
$\omega$. Based on these results, we investigate the periodic orbits in the
Kehagias-Sfetsos black holes. It is found that the apsidal angle parameter
increases with the particle energy, while decreases with the angular momentum.
Moreover, compared to the Schwarzschild black hole, the periodic orbits in
Kehagias-Sfetsos black holes always have lower energy. These results provide us
a possible way to distinguish the Kehagias-Sfetsos black hole in deformed
Ho\u{r}ava-Lifshitz gravity from the Schwarzschild black hole.
| [
{
"created": "Fri, 5 Apr 2019 15:47:14 GMT",
"version": "v1"
},
{
"created": "Wed, 29 May 2019 03:32:42 GMT",
"version": "v2"
}
] | 2019-05-30 | [
[
"Wei",
"Shao-Wen",
""
],
[
"Yang",
"Jie",
""
],
[
"Liu",
"Yu-Xiao",
""
]
] | The motion of a massive test particle around a Kehagias-Sfetsos black hole in deformed Ho\u{r}ava-Lifshitz gravity is studied. Employing the effective potential, the marginally bound orbits and the innermost stable circular orbits are analyzed. For the marginally bound orbits, their radius and angular momentum decrease with the parameter $\omega$ of the gravity. For the innermost stable circular orbits, the energy and angular momentum also decrease with $\omega$. Based on these results, we investigate the periodic orbits in the Kehagias-Sfetsos black holes. It is found that the apsidal angle parameter increases with the particle energy, while decreases with the angular momentum. Moreover, compared to the Schwarzschild black hole, the periodic orbits in Kehagias-Sfetsos black holes always have lower energy. These results provide us a possible way to distinguish the Kehagias-Sfetsos black hole in deformed Ho\u{r}ava-Lifshitz gravity from the Schwarzschild black hole. |
1111.6821 | Cenalo Vaz | Cenalo Vaz and Louis Witten | Canonical Quantization of Spherically Symmetric Dust Collapse | 19 pages no figures. Contribution to a festschrift in honor of Joshua
N. Goldberg | Gen.Rel.Grav.43:3429,2011 | 10.1007/s10714-011-1240-4 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Quantum gravity effects are likely to play a crucial role in determining the
outcome of gravitational collapse during its final stages. In this contribution
we will outline a canonical quantization of the LeMaitre-Tolman-Bondi models,
which describe the collapse of spherical, inhomogeneous, non-rotating dust.
Although there are many models of gravitational collapse, this particular class
of models stands out for its simplicity and the fact that both black holes and
naked singularity end states may be realized on the classical level, depending
on the initial conditions. We will obtain the appropriate Wheeler-DeWitt
equation and then solve it exactly, after regularization on a spatial lattice.
The solutions describe Hawking radiation and provide an elegant microcanonical
description of black hole entropy, but they raise other questions, most
importantly concerning the nature of gravity's fundamental degrees of freedom.
| [
{
"created": "Tue, 29 Nov 2011 14:26:43 GMT",
"version": "v1"
}
] | 2011-12-01 | [
[
"Vaz",
"Cenalo",
""
],
[
"Witten",
"Louis",
""
]
] | Quantum gravity effects are likely to play a crucial role in determining the outcome of gravitational collapse during its final stages. In this contribution we will outline a canonical quantization of the LeMaitre-Tolman-Bondi models, which describe the collapse of spherical, inhomogeneous, non-rotating dust. Although there are many models of gravitational collapse, this particular class of models stands out for its simplicity and the fact that both black holes and naked singularity end states may be realized on the classical level, depending on the initial conditions. We will obtain the appropriate Wheeler-DeWitt equation and then solve it exactly, after regularization on a spatial lattice. The solutions describe Hawking radiation and provide an elegant microcanonical description of black hole entropy, but they raise other questions, most importantly concerning the nature of gravity's fundamental degrees of freedom. |
gr-qc/9811007 | Roland Steinbauer | Michael Kunzinger, Roland Steinbauer | A note on the Penrose junction conditions | 9 pages, RevTeX, no figures, final version (typos corrected,
references updated) | Class.Quant.Grav. 16 (1999) 1255-1264 | 10.1088/0264-9381/16/4/013 | UWThPh-1998-57 | gr-qc math-ph math.MP | null | Impulsive pp-waves are commonly described either by a distributional
spacetime metric or, alternatively, by a continuous one. The transformation $T$
relating these forms clearly has to be discontinuous, which causes two basic
problems: First, it changes the manifold structure and second, the pullback of
the distributional form of the metric under $T$ is not well defined within
classical distribution theory. Nevertheless, from a physical point of view both
pictures are equivalent. In this work, after calculating $T$ als well as the
''Rosen''-form of the metric in the general case of a pp-wave with arbitrary
wave profile we give a precise meaning to the term ``physically equivalent'' by
interpreting $T$ as the distributional limit of a suitably regularized sequence
of diffeomorphisms. Moreover, it is shown that $T$ provides an example of a
generalized coordinate transformation in the sense of Colombeau's generalized
functions.
| [
{
"created": "Tue, 3 Nov 1998 08:59:53 GMT",
"version": "v1"
},
{
"created": "Mon, 19 Apr 1999 13:12:12 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Kunzinger",
"Michael",
""
],
[
"Steinbauer",
"Roland",
""
]
] | Impulsive pp-waves are commonly described either by a distributional spacetime metric or, alternatively, by a continuous one. The transformation $T$ relating these forms clearly has to be discontinuous, which causes two basic problems: First, it changes the manifold structure and second, the pullback of the distributional form of the metric under $T$ is not well defined within classical distribution theory. Nevertheless, from a physical point of view both pictures are equivalent. In this work, after calculating $T$ als well as the ''Rosen''-form of the metric in the general case of a pp-wave with arbitrary wave profile we give a precise meaning to the term ``physically equivalent'' by interpreting $T$ as the distributional limit of a suitably regularized sequence of diffeomorphisms. Moreover, it is shown that $T$ provides an example of a generalized coordinate transformation in the sense of Colombeau's generalized functions. |
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