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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1107.0694 | Eduardo Rodrigues | H. P. de Oliveira, E. L. Rodrigues and J. E. F. Skea | Numerical evolution of general Robinson-Trautman spacetimes: code tests,
wave forms and the efficiency of the gravitational wave extraction | 12 pages, 5 figures. To appear in Physical Review D | Phys.Rev.D84:044007,2011 | 10.1103/PhysRevD.84.044007 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present an efficient numerical code based on spectral methods to integrate
the field equations of general Robinson-Trautmann spacetimes. The most natural
basis functions for the spectral expansion of the metric functions are
spherical harmonics. Using the values of appropriate combinations of the metric
functions at the collocation points, we have managed to reduce expression swell
when the number of spherical harmonics increases. Our numerical code runs with
relatively little computational resources and the code tests have shown
excellent accuracy and convergence. The code has been applied to situations of
physical interest in the context of Robsinson-Trautmann geometries such as:
perturbation of the exterior gravitational field of a spheroid of matter;
perturbation of an initially boosted black hole; and the non-frontal collision
of two Schwarzschild black holes. In dealing with these processes we have
derived analytical lower and upper bounds on the velocity of the resulting
black hole and the efficiency of the gravitational wave extraction,
respectively. Numerical experiments were performed to determine the forms of
the gravitational waves and the efficiency in each situation of interest.
| [
{
"created": "Mon, 4 Jul 2011 18:11:53 GMT",
"version": "v1"
}
] | 2011-11-10 | [
[
"de Oliveira",
"H. P.",
""
],
[
"Rodrigues",
"E. L.",
""
],
[
"Skea",
"J. E. F.",
""
]
] | We present an efficient numerical code based on spectral methods to integrate the field equations of general Robinson-Trautmann spacetimes. The most natural basis functions for the spectral expansion of the metric functions are spherical harmonics. Using the values of appropriate combinations of the metric functions at the collocation points, we have managed to reduce expression swell when the number of spherical harmonics increases. Our numerical code runs with relatively little computational resources and the code tests have shown excellent accuracy and convergence. The code has been applied to situations of physical interest in the context of Robsinson-Trautmann geometries such as: perturbation of the exterior gravitational field of a spheroid of matter; perturbation of an initially boosted black hole; and the non-frontal collision of two Schwarzschild black holes. In dealing with these processes we have derived analytical lower and upper bounds on the velocity of the resulting black hole and the efficiency of the gravitational wave extraction, respectively. Numerical experiments were performed to determine the forms of the gravitational waves and the efficiency in each situation of interest. |
0809.3564 | Lorenzo Iorio | Lorenzo Iorio | On the impact of the atmospheric drag on the LARES mission | Latex2e, 19 pages, 2 tables, no figures. Final version to appear in
Acta Physica Polonica (AcPP). | Acta Phys. Polon.B41:753-765,2010 | null | null | gr-qc astro-ph astro-ph.EP physics.geo-ph physics.space-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The goal of the recently approved space-based LARES mission is to measure the
general relativistic Lense-Thirring effect in the gravitational field of the
spinning Earth at a repeatedly claimed 1% accuracy by combining its node Omega
with those of the existing LAGEOS and LAGEOS II laser-ranged satellites. In
this paper we show that, in view of the lower altitude of LARES (h=1450 km)
with respect to LAGEOS and LAGEOS II (h\approx 6000 km), the cross-coupling
between the effect of the atmospheric drag, both neutral and charged, on the
inclination of LARES and its classical node precession due to the Earth's
oblateness may induce a 3-9% year^-1 systematic bias on the total relativistic
precession. Since its extraction from the data will take about 5-10 years, such
a perturbing effect may degrade the total accuracy of the test, especially in
view of the large uncertainties in modeling the drag force.
| [
{
"created": "Sun, 21 Sep 2008 09:02:04 GMT",
"version": "v1"
},
{
"created": "Wed, 8 Oct 2008 13:55:20 GMT",
"version": "v2"
},
{
"created": "Tue, 6 Oct 2009 07:16:20 GMT",
"version": "v3"
},
{
"created": "Wed, 17 Mar 2010 16:35:54 GMT",
"version": "v4"
}
] | 2010-04-28 | [
[
"Iorio",
"Lorenzo",
""
]
] | The goal of the recently approved space-based LARES mission is to measure the general relativistic Lense-Thirring effect in the gravitational field of the spinning Earth at a repeatedly claimed 1% accuracy by combining its node Omega with those of the existing LAGEOS and LAGEOS II laser-ranged satellites. In this paper we show that, in view of the lower altitude of LARES (h=1450 km) with respect to LAGEOS and LAGEOS II (h\approx 6000 km), the cross-coupling between the effect of the atmospheric drag, both neutral and charged, on the inclination of LARES and its classical node precession due to the Earth's oblateness may induce a 3-9% year^-1 systematic bias on the total relativistic precession. Since its extraction from the data will take about 5-10 years, such a perturbing effect may degrade the total accuracy of the test, especially in view of the large uncertainties in modeling the drag force. |
0704.3764 | P Ajith | P. Ajith, S. Babak, Y. Chen, M. Hewitson, B. Krishnan, J. T. Whelan,
B. Bruegmann, P. Diener, J. Gonzalez, M. Hannam, S. Husa, M. Koppitz, D.
Pollney, L. Rezzolla, L. Santamaria, A. M. Sintes, U. Sperhake and J.
Thornburg | Phenomenological template family for black-hole coalescence waveforms | Minor changes, Submitted to Class. Quantum Grav. (Proc. GWDAW11) | Class.Quant.Grav.24:S689-S700,2007 | 10.1088/0264-9381/24/19/S31 | AEI-2007-029 | gr-qc astro-ph | null | Recent progress in numerical relativity has enabled us to model the
non-perturbative merger phase of the binary black-hole coalescence problem.
Based on these results, we propose a phenomenological family of waveforms which
can model the inspiral, merger, and ring-down stages of black hole coalescence.
We also construct a template bank using this family of waveforms and discuss
its implementation in the search for signatures of gravitational waves produced
by black-hole coalescences in the data of ground-based interferometers. This
template bank might enable us to extend the present inspiral searches to
higher-mass binary black-hole systems, i.e., systems with total mass greater
than about 80 solar masses, thereby increasing the reach of the current
generation of ground-based detectors.
| [
{
"created": "Mon, 30 Apr 2007 15:45:13 GMT",
"version": "v1"
},
{
"created": "Tue, 1 May 2007 08:52:02 GMT",
"version": "v2"
},
{
"created": "Wed, 11 Jul 2007 13:21:33 GMT",
"version": "v3"
}
] | 2008-11-26 | [
[
"Ajith",
"P.",
""
],
[
"Babak",
"S.",
""
],
[
"Chen",
"Y.",
""
],
[
"Hewitson",
"M.",
""
],
[
"Krishnan",
"B.",
""
],
[
"Whelan",
"J. T.",
""
],
[
"Bruegmann",
"B.",
""
],
[
"Diener",
"P.",
... | Recent progress in numerical relativity has enabled us to model the non-perturbative merger phase of the binary black-hole coalescence problem. Based on these results, we propose a phenomenological family of waveforms which can model the inspiral, merger, and ring-down stages of black hole coalescence. We also construct a template bank using this family of waveforms and discuss its implementation in the search for signatures of gravitational waves produced by black-hole coalescences in the data of ground-based interferometers. This template bank might enable us to extend the present inspiral searches to higher-mass binary black-hole systems, i.e., systems with total mass greater than about 80 solar masses, thereby increasing the reach of the current generation of ground-based detectors. |
gr-qc/9603040 | Yuri N. Obukhov | Yuri N. Obukhov and Sergey I. Tertychniy | Vacuum Einstein Equations in Terms of Curvature Forms | 30 pages, RevTex | Class.Quant.Grav. 13 (1996) 1623-1640 | 10.1088/0264-9381/13/6/025 | null | gr-qc | null | A closed explicit representation of the vacuum Einstein equations in terms of
components of curvature 2-forms is given. The discussion is restricted to the
case of non-vanishing cubic invariant of conformal curvature spinor. The
complete set of algebraic and differential identities connecting particular
equations is presented and their consistency conditions are analyzed.
| [
{
"created": "Sun, 24 Mar 1996 16:44:04 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Obukhov",
"Yuri N.",
""
],
[
"Tertychniy",
"Sergey I.",
""
]
] | A closed explicit representation of the vacuum Einstein equations in terms of components of curvature 2-forms is given. The discussion is restricted to the case of non-vanishing cubic invariant of conformal curvature spinor. The complete set of algebraic and differential identities connecting particular equations is presented and their consistency conditions are analyzed. |
1511.09135 | Yongwan Gim | Myungseok Eune, Yongwan Gim, and Wontae Kim | Effective Tolman temperature induced by trace anomaly | 11 pages, 1 figure, version to appear in EPJC | Eur. Phys. J. C77 (2017) 244 | 10.1140/epjc/s10052-017-4812-y | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Despite the finiteness of stress tensor for a scalar field on the
four-dimensional Schwarzschild black hole in the Israel-Hartle-Hawking vacuum,
the Tolman temperature in thermal equilibrium is certainly divergent on the
horizon due to the infinite blueshift of the Hawking temperature. The origin of
this conflict is due to the fact that the conventional Tolman temperature was
based on the assumption of a traceless stress tensor, which is, however,
incompatible with the presence of the trace anomaly responsible for the Hawking
radiation. Here, we present an effective Tolman temperature which is compatible
with the presence of the trace anomaly by using the modified Stefan-Boltzmann
law. Eventually, the effective Tolman temperature turns out to be finite
everywhere outside the horizon, and so there does not appear infinite blueshift
of the Hawking temperature at the event horizon any more. In particular, it is
vanishing on the horizon, so that the equivalence principle is exactly
recovered at the horizon.
| [
{
"created": "Mon, 30 Nov 2015 02:14:11 GMT",
"version": "v1"
},
{
"created": "Thu, 10 Dec 2015 05:26:53 GMT",
"version": "v2"
},
{
"created": "Thu, 28 Apr 2016 05:00:44 GMT",
"version": "v3"
},
{
"created": "Fri, 20 Jan 2017 09:21:38 GMT",
"version": "v4"
},
{
"c... | 2017-06-26 | [
[
"Eune",
"Myungseok",
""
],
[
"Gim",
"Yongwan",
""
],
[
"Kim",
"Wontae",
""
]
] | Despite the finiteness of stress tensor for a scalar field on the four-dimensional Schwarzschild black hole in the Israel-Hartle-Hawking vacuum, the Tolman temperature in thermal equilibrium is certainly divergent on the horizon due to the infinite blueshift of the Hawking temperature. The origin of this conflict is due to the fact that the conventional Tolman temperature was based on the assumption of a traceless stress tensor, which is, however, incompatible with the presence of the trace anomaly responsible for the Hawking radiation. Here, we present an effective Tolman temperature which is compatible with the presence of the trace anomaly by using the modified Stefan-Boltzmann law. Eventually, the effective Tolman temperature turns out to be finite everywhere outside the horizon, and so there does not appear infinite blueshift of the Hawking temperature at the event horizon any more. In particular, it is vanishing on the horizon, so that the equivalence principle is exactly recovered at the horizon. |
2112.03282 | Tiago V. Fernandes | Tiago V. Fernandes, David Hilditch, Jos\'e P. S. Lemos, Vitor Cardoso | Quasinormal modes of Proca fields in a Schwarzschild-AdS spacetime | 15 pages, 4 tables, 1 appendix with 2 figures | Phys. Rev. D 105, 044017 (2022) | 10.1103/PhysRevD.105.044017 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We present new results concerning the Proca massive vector field in a
Schwarzschild-AdS black hole geometry. We provide a first principles analysis
of Proca vector fields in this geometry using both the vector spherical
harmonic (VSH) separation method and the
Frolov-Krtou\v{s}-Kubiz\v{n}\'{a}k-Santos (FKKS) method that separates the
relevant equations in spinning geometries. The analysis in the VSH method
shows, on one hand, that it is arduous to separate the scalar-type from the
vector-type polarizations of the electric sector of the Proca field, and on the
other hand, it displays clearly the electric and the magnetic mode sectors. The
analysis in the FKKS method is performed by taking the nonrotating limit of the
Kerr-AdS spacetime, and shows that the ansatz decouples the polarizations in
the electric mode sector even in the nonrotating limit. On the other hand, it
captures only two of the three possible polarizations, the magnetic mode sector
is missing. The reason for the absence of this polarization is related to the
degeneracy of the principal tensor in static spherical symmetric spacetimes.
The degrees of freedom and quasinormal modes in both separation methods of the
Proca field are found. The frequencies of the quasinormal modes are also
computed. For the electric mode sector in the VSH method the frequencies are
found through an extension, which substitutes number coefficients by matrix
coefficients, of the Horowitz-Hubeny numerical procedure, whereas for the
magnetic mode sector in the VSH method and the electric sector of the FKKS
method it is shown that a direct use of the procedure can be made. The values
of the quasinormal mode frequencies obtained for each method are compared and
showed to be in good agreement with each other. This further supports the
analytical approaches presented here for the behavior of the Proca field in a
Schwarzschild-AdS black hole background.
| [
{
"created": "Mon, 6 Dec 2021 19:00:01 GMT",
"version": "v1"
},
{
"created": "Thu, 10 Feb 2022 17:42:44 GMT",
"version": "v2"
}
] | 2022-02-11 | [
[
"Fernandes",
"Tiago V.",
""
],
[
"Hilditch",
"David",
""
],
[
"Lemos",
"José P. S.",
""
],
[
"Cardoso",
"Vitor",
""
]
] | We present new results concerning the Proca massive vector field in a Schwarzschild-AdS black hole geometry. We provide a first principles analysis of Proca vector fields in this geometry using both the vector spherical harmonic (VSH) separation method and the Frolov-Krtou\v{s}-Kubiz\v{n}\'{a}k-Santos (FKKS) method that separates the relevant equations in spinning geometries. The analysis in the VSH method shows, on one hand, that it is arduous to separate the scalar-type from the vector-type polarizations of the electric sector of the Proca field, and on the other hand, it displays clearly the electric and the magnetic mode sectors. The analysis in the FKKS method is performed by taking the nonrotating limit of the Kerr-AdS spacetime, and shows that the ansatz decouples the polarizations in the electric mode sector even in the nonrotating limit. On the other hand, it captures only two of the three possible polarizations, the magnetic mode sector is missing. The reason for the absence of this polarization is related to the degeneracy of the principal tensor in static spherical symmetric spacetimes. The degrees of freedom and quasinormal modes in both separation methods of the Proca field are found. The frequencies of the quasinormal modes are also computed. For the electric mode sector in the VSH method the frequencies are found through an extension, which substitutes number coefficients by matrix coefficients, of the Horowitz-Hubeny numerical procedure, whereas for the magnetic mode sector in the VSH method and the electric sector of the FKKS method it is shown that a direct use of the procedure can be made. The values of the quasinormal mode frequencies obtained for each method are compared and showed to be in good agreement with each other. This further supports the analytical approaches presented here for the behavior of the Proca field in a Schwarzschild-AdS black hole background. |
2109.12336 | Javier Relancio | J.J. Relancio, S. Liberati | Black hole surface gravity in doubly special relativity geometries | 11 pages | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In a quantum gravity theory, spacetime at mesoscopic scales can acquire a
novel structure very different from the classical concept of general
relativity. A way to effectively characterize the quantum nature of spacetime
is through a momentum dependent space-time metric. There is a vast literature
showing that this geometry is related to deformed relativistic kinematics,
which is precisely a way to capture residual effects of a quantum gravity
theory. In this work, we study the notion of surface gravity in a momentum
dependent Schwarzschild black hole geometry. We show that using the two main
notions of surface gravity in general relativity we obtain a momentum
independent result. However, there are several definitions of surface gravity,
all of them equivalent in general relativity when there is a Killing horizon.
We show that in our scheme, despite the persistence of a Killing horizon, these
alternative notions only agree in a very particular momentum basis, obtained in
a previous work, so further supporting its physical relevance.
| [
{
"created": "Sat, 25 Sep 2021 10:53:49 GMT",
"version": "v1"
}
] | 2021-09-28 | [
[
"Relancio",
"J. J.",
""
],
[
"Liberati",
"S.",
""
]
] | In a quantum gravity theory, spacetime at mesoscopic scales can acquire a novel structure very different from the classical concept of general relativity. A way to effectively characterize the quantum nature of spacetime is through a momentum dependent space-time metric. There is a vast literature showing that this geometry is related to deformed relativistic kinematics, which is precisely a way to capture residual effects of a quantum gravity theory. In this work, we study the notion of surface gravity in a momentum dependent Schwarzschild black hole geometry. We show that using the two main notions of surface gravity in general relativity we obtain a momentum independent result. However, there are several definitions of surface gravity, all of them equivalent in general relativity when there is a Killing horizon. We show that in our scheme, despite the persistence of a Killing horizon, these alternative notions only agree in a very particular momentum basis, obtained in a previous work, so further supporting its physical relevance. |
1001.0031 | Foek Hioe | F.T. Hioe and David Kuebel | Characterizing Planetary Orbits and the Trajectories of Light | 49 pages total with 11 tables and 10 figures | Phys.Rev.D81:084017,2010 | 10.1103/PhysRevD.81.084017 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Exact analytic expressions for planetary orbits and light trajectories in the
Schwarzschild geometry are presented. A new parameter space is used to
characterize all possible planetary orbits. Different regions in this parameter
space can be associated with different characteristics of the orbits. The
boundaries for these regions are clearly defined. Observational data can be
directly associated with points in the regions. A possible extension of these
considerations with an additional parameter for the case of Kerr geometry is
briefly discussed.
| [
{
"created": "Wed, 30 Dec 2009 21:38:20 GMT",
"version": "v1"
}
] | 2010-04-30 | [
[
"Hioe",
"F. T.",
""
],
[
"Kuebel",
"David",
""
]
] | Exact analytic expressions for planetary orbits and light trajectories in the Schwarzschild geometry are presented. A new parameter space is used to characterize all possible planetary orbits. Different regions in this parameter space can be associated with different characteristics of the orbits. The boundaries for these regions are clearly defined. Observational data can be directly associated with points in the regions. A possible extension of these considerations with an additional parameter for the case of Kerr geometry is briefly discussed. |
0803.2348 | Achamveedu Gopakumar | Achamveedu Gopakumar and Gerhard Schaefer | Binary Black Hole Coalescence in Semi-Analytic Puncture Evolution | 16 pages, 5 figures | Phys.Rev.D77:104023,2008 | 10.1103/PhysRevD.77.104023 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Binary black-hole coalescence is treated semi-analytically by a novel
approach. Our prescription employs the conservative Skeleton Hamiltonian that
describes orbiting Brill-Lindquist wormholes (termed punctures in Numerical
Relativity) within a waveless truncation to the Einstein field equations [G.
Faye, P. Jaranowski and G. Sch\"afer, Phys. Rev. D {\bf 69}, 124029 (2004)]. We
incorporate, in a transparent Hamiltonian way and in Burke-Thorne gauge
structure, the effects of gravitational radiation reaction into the above
Skeleton dynamics with the help of 3.5PN accurate angular momentum flux for
compact binaries in quasi-circular orbits to obtain a Semi-Analytic Puncture
Evolution to model merging black-hole binaries. With the help of the TaylorT4
approximant at 3.5PN order, we perform a {\it first-order} comparison between
gravitational wave phase evolutions in Numerical Relativity and our approach
for equal-mass binary black holes. This comparison reveals that a modified
Skeletonian reactive dynamics that employs flexible parameters will be required
to prevent the dephasing between our scheme and Numerical Relativity, similar
to what is pursued in the Effective One Body approach. A rough estimate for the
gravitational waveform associated with the binary black-hole coalescence in our
approach is also provided.
| [
{
"created": "Sun, 16 Mar 2008 12:41:18 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Gopakumar",
"Achamveedu",
""
],
[
"Schaefer",
"Gerhard",
""
]
] | Binary black-hole coalescence is treated semi-analytically by a novel approach. Our prescription employs the conservative Skeleton Hamiltonian that describes orbiting Brill-Lindquist wormholes (termed punctures in Numerical Relativity) within a waveless truncation to the Einstein field equations [G. Faye, P. Jaranowski and G. Sch\"afer, Phys. Rev. D {\bf 69}, 124029 (2004)]. We incorporate, in a transparent Hamiltonian way and in Burke-Thorne gauge structure, the effects of gravitational radiation reaction into the above Skeleton dynamics with the help of 3.5PN accurate angular momentum flux for compact binaries in quasi-circular orbits to obtain a Semi-Analytic Puncture Evolution to model merging black-hole binaries. With the help of the TaylorT4 approximant at 3.5PN order, we perform a {\it first-order} comparison between gravitational wave phase evolutions in Numerical Relativity and our approach for equal-mass binary black holes. This comparison reveals that a modified Skeletonian reactive dynamics that employs flexible parameters will be required to prevent the dephasing between our scheme and Numerical Relativity, similar to what is pursued in the Effective One Body approach. A rough estimate for the gravitational waveform associated with the binary black-hole coalescence in our approach is also provided. |
1404.6316 | Yu Seon Jeong | Choong Sun Kim | Extended Uncertainty Relation and Rough Estimate of Cosmological
Constant | 6 pages | null | null | null | gr-qc hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | One brief idea on the extended uncertainty relation and the dynamical
quantization of space-time at the Planck scale is presented. The extended
uncertainty relation could be a guiding principle toward the renormalizable
quantum gravity. Cosmological constant in the Universe as a quantum effect is
also roughly estimated.
| [
{
"created": "Fri, 25 Apr 2014 04:37:39 GMT",
"version": "v1"
}
] | 2014-04-28 | [
[
"Kim",
"Choong Sun",
""
]
] | One brief idea on the extended uncertainty relation and the dynamical quantization of space-time at the Planck scale is presented. The extended uncertainty relation could be a guiding principle toward the renormalizable quantum gravity. Cosmological constant in the Universe as a quantum effect is also roughly estimated. |
1802.08000 | Luciano Gabbanelli | Luciano Gabbanelli, \'Angel Rinc\'on, Carlos Rubio | Gravitational decoupled anisotropies in compact stars | 21 pages, 5 figures | Eur. Phys. J. C (2018) 78: 370 | 10.1140/epjc/s10052-018-5865-2 | ICCUB-18-003 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Simple generic extensions of isotropic Durgapal--Fuloria stars to the
anisotropic domain are presented. These anisotropic solutions are obtained by
guided minimal deformations over a self gravitating isotropic system. When the
isotropic and the anisotropic sector interacts in a purely gravitational
manner, the conditions to decouple both sectors by means of the minimal
geometric deformation approach are satisfied. Hence the anisotropic field
equations are isolated resulting a more treatable set. The simplicity of the
equations allows one to manipulate the anisotropies that can be implemented in
a systematic way to obtain different realistic models for anisotropic
configurations. Later on, observational effects of such anisotropies when
measuring the redshift are discussed. To conclude, the application of the
method over anisotropic solutions is generalized. In this manner, different
anisotropic sectors can be isolated of each other and modeled in a simple and
systematic way. Besides, a generic property of the minimal geometric
deformation approach, its noncommutativity, is discussed. This property
duplicates the solutions obtained through this approach; anisotropies applied
in the reversed order give different physically acceptable configurations.
| [
{
"created": "Thu, 22 Feb 2018 11:59:08 GMT",
"version": "v1"
}
] | 2018-07-04 | [
[
"Gabbanelli",
"Luciano",
""
],
[
"Rincón",
"Ángel",
""
],
[
"Rubio",
"Carlos",
""
]
] | Simple generic extensions of isotropic Durgapal--Fuloria stars to the anisotropic domain are presented. These anisotropic solutions are obtained by guided minimal deformations over a self gravitating isotropic system. When the isotropic and the anisotropic sector interacts in a purely gravitational manner, the conditions to decouple both sectors by means of the minimal geometric deformation approach are satisfied. Hence the anisotropic field equations are isolated resulting a more treatable set. The simplicity of the equations allows one to manipulate the anisotropies that can be implemented in a systematic way to obtain different realistic models for anisotropic configurations. Later on, observational effects of such anisotropies when measuring the redshift are discussed. To conclude, the application of the method over anisotropic solutions is generalized. In this manner, different anisotropic sectors can be isolated of each other and modeled in a simple and systematic way. Besides, a generic property of the minimal geometric deformation approach, its noncommutativity, is discussed. This property duplicates the solutions obtained through this approach; anisotropies applied in the reversed order give different physically acceptable configurations. |
0709.4607 | Z. Ya. Turakulov | A.T. Muminov | Motion of Spin 1/2 Massive Particle in a Curved Spacetime | 9 pages | null | null | null | gr-qc | null | Quasi-classical picture of motion of spin 1/2 massive particle in a curved
spacetime is built on base of simple Lagrangian model. The one is constructed
due to analogy with Lagrangian of massive vector particle. Equations of motion
and spin propagation coincide with Papapetrou equations describing dynamic of
classical spinning particle in a curved spacetime.
| [
{
"created": "Fri, 28 Sep 2007 12:55:32 GMT",
"version": "v1"
}
] | 2007-10-01 | [
[
"Muminov",
"A. T.",
""
]
] | Quasi-classical picture of motion of spin 1/2 massive particle in a curved spacetime is built on base of simple Lagrangian model. The one is constructed due to analogy with Lagrangian of massive vector particle. Equations of motion and spin propagation coincide with Papapetrou equations describing dynamic of classical spinning particle in a curved spacetime. |
1310.8376 | Cosimo Bambi | Lingyao Kong, Daniele Malafarina, Cosimo Bambi | Can we observationally test the weak cosmic censorship conjecture? | 1+19 pages, 4 figures. v2: minor changes | Eur.Phys.J.C74:2983,2014 | 10.1140/epjc/s10052-014-2983-3 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In general relativity, gravitational collapse of matter fields ends with the
formation of a spacetime singularity, where the matter density becomes infinite
and standard physics breaks down. According to the weak cosmic censorship
conjecture, singularities produced in the gravitational collapse cannot be seen
by distant observers and must be hidden within black holes. The validity of
this conjecture is still controversial and at present we cannot exclude that
naked singularities can be created in our Universe from regular initial data.
In this paper, we study the radiation emitted by a collapsing cloud of dust and
check whether it is possible to distinguish the birth of a black hole from the
one of a naked singularity. In our simple dust model, we find that the
properties of the radiation emitted in the two scenarios is qualitatively
similar. That suggests that observational tests of the cosmic censorship
conjecture may be very difficult, even in principle.
| [
{
"created": "Thu, 31 Oct 2013 04:20:48 GMT",
"version": "v1"
},
{
"created": "Mon, 4 Aug 2014 14:00:13 GMT",
"version": "v2"
}
] | 2014-08-05 | [
[
"Kong",
"Lingyao",
""
],
[
"Malafarina",
"Daniele",
""
],
[
"Bambi",
"Cosimo",
""
]
] | In general relativity, gravitational collapse of matter fields ends with the formation of a spacetime singularity, where the matter density becomes infinite and standard physics breaks down. According to the weak cosmic censorship conjecture, singularities produced in the gravitational collapse cannot be seen by distant observers and must be hidden within black holes. The validity of this conjecture is still controversial and at present we cannot exclude that naked singularities can be created in our Universe from regular initial data. In this paper, we study the radiation emitted by a collapsing cloud of dust and check whether it is possible to distinguish the birth of a black hole from the one of a naked singularity. In our simple dust model, we find that the properties of the radiation emitted in the two scenarios is qualitatively similar. That suggests that observational tests of the cosmic censorship conjecture may be very difficult, even in principle. |
1010.5740 | Alexander Zhuk | Maxim Eingorn and Alexander Zhuk | Kaluza-Klein models: can we construct a viable example? | 11 pages, Revtex4, no figures, appendix and references added | Phys.Rev.D83:044005,2011 | 10.1103/PhysRevD.83.044005 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In Kaluza-Klein models, we investigate soliton solutions of Einstein
equation. We obtain the formulas for perihelion shift, deflection of light,
time delay of radar echoes and PPN parameters. We find that the solitonic
parameter k should be very big: |k|\geq 2.3\times10^4. We define a soliton
solution which corresponds to a point-like mass source. In this case the
soliton parameter k=2, which is clearly contrary to this restriction. Similar
problem with the observations takes place for static spherically symmetric
perfect fluid with the dust-like equation of state in all dimensions. The
common for both of these models is the same equations of state in our three
dimensions and in the extra dimensions. All dimensions are treated at equal
footing. To be in agreement with observations, it is necessary to break the
symmetry between the external/our and internal spaces. It takes place for black
strings which are particular examples of solitons with k\to \infty. For such k,
black strings are in concordance with the observations. Moreover, we show that
they are the only solitons which are at the same level of agreement with the
observations as in general relativity. Black strings can be treated as perfect
fluid with dust-like equation of state p_0=0 in the external/our space and very
specific equation of state p_1=-(1/2)\epsilon in the internal space. The latter
equation is due to negative tension in the extra dimension. We also demonstrate
that dimension 3 for the external space is a special one. Only in this case we
get the latter equation of state. We show that the black string equations of
state satisfy the necessary condition of the internal space stabilization.
Therefore, black strings are good candidates for a viable model of
astrophysical objects (e.g., Sun) if we can provide a satisfactory explanation
of negative tension for particles constituting these objects.
| [
{
"created": "Wed, 27 Oct 2010 16:49:28 GMT",
"version": "v1"
},
{
"created": "Tue, 7 Dec 2010 14:39:34 GMT",
"version": "v2"
}
] | 2011-02-15 | [
[
"Eingorn",
"Maxim",
""
],
[
"Zhuk",
"Alexander",
""
]
] | In Kaluza-Klein models, we investigate soliton solutions of Einstein equation. We obtain the formulas for perihelion shift, deflection of light, time delay of radar echoes and PPN parameters. We find that the solitonic parameter k should be very big: |k|\geq 2.3\times10^4. We define a soliton solution which corresponds to a point-like mass source. In this case the soliton parameter k=2, which is clearly contrary to this restriction. Similar problem with the observations takes place for static spherically symmetric perfect fluid with the dust-like equation of state in all dimensions. The common for both of these models is the same equations of state in our three dimensions and in the extra dimensions. All dimensions are treated at equal footing. To be in agreement with observations, it is necessary to break the symmetry between the external/our and internal spaces. It takes place for black strings which are particular examples of solitons with k\to \infty. For such k, black strings are in concordance with the observations. Moreover, we show that they are the only solitons which are at the same level of agreement with the observations as in general relativity. Black strings can be treated as perfect fluid with dust-like equation of state p_0=0 in the external/our space and very specific equation of state p_1=-(1/2)\epsilon in the internal space. The latter equation is due to negative tension in the extra dimension. We also demonstrate that dimension 3 for the external space is a special one. Only in this case we get the latter equation of state. We show that the black string equations of state satisfy the necessary condition of the internal space stabilization. Therefore, black strings are good candidates for a viable model of astrophysical objects (e.g., Sun) if we can provide a satisfactory explanation of negative tension for particles constituting these objects. |
2201.12956 | Puskar Mondal | Puskar Mondal, Shing-Tung Yau | Aspects of Quasi-local energy for gravity coupled to gauge fields | 22 pages | null | 10.1103/PhysRevD.105.104068 | null | gr-qc math-ph math.MP | http://creativecommons.org/licenses/by/4.0/ | We study the aspects of quasi-local energy associated with a $2-$surface
$\Sigma$ bounding a space-like domain $\Omega$ of a physical $3+1$ dimensional
spacetime in the regime of gravity coupled to a gauge field. The Wang-Yau
quasi-local energy together with an additional term arising due to the coupling
of gravity to a gauge field constitutes the total energy ($\mathcal{QLE}$)
contained within the membrane $\Sigma=\partial\Omega$. We specialize in the
Kerr-Newman family of spacetimes which contains a U(1) gauge field coupled to
gravity and an outer horizon. Through explicit calculations, we show that the
total energy satisfies a weaker version of a Bekenstein type inequality
$\mathcal{QLE}> \frac{Q^{2}}{2R}$ for large spherical membranes, $Q$ is the
charge and $R$ is the radius of the membrane. Turning off the angular momentum
(Reissner Nordstr\"om) yields $\mathcal{QLE}> \frac{Q^{2}}{2R}$ for all
constant radii membranes containing the horizon and in such case the charge
factor appearing in the right-hand side exactly equals to that of Bekenstein's
inequality. Moreover, we show that the total quasi-local energy monotonically
decays from $2M_{irr}+V_{Q}$ ($M_{irr}$ is the irreducible mass, $V_{Q}$ is the
electric potential energy) at the outer horizon to $M$ ($M$ is the ADM mass) at
the space-like infinity under the assumption of a small angular momentum of the
black hole.
| [
{
"created": "Mon, 31 Jan 2022 01:45:26 GMT",
"version": "v1"
},
{
"created": "Mon, 28 Feb 2022 01:12:21 GMT",
"version": "v2"
}
] | 2022-06-15 | [
[
"Mondal",
"Puskar",
""
],
[
"Yau",
"Shing-Tung",
""
]
] | We study the aspects of quasi-local energy associated with a $2-$surface $\Sigma$ bounding a space-like domain $\Omega$ of a physical $3+1$ dimensional spacetime in the regime of gravity coupled to a gauge field. The Wang-Yau quasi-local energy together with an additional term arising due to the coupling of gravity to a gauge field constitutes the total energy ($\mathcal{QLE}$) contained within the membrane $\Sigma=\partial\Omega$. We specialize in the Kerr-Newman family of spacetimes which contains a U(1) gauge field coupled to gravity and an outer horizon. Through explicit calculations, we show that the total energy satisfies a weaker version of a Bekenstein type inequality $\mathcal{QLE}> \frac{Q^{2}}{2R}$ for large spherical membranes, $Q$ is the charge and $R$ is the radius of the membrane. Turning off the angular momentum (Reissner Nordstr\"om) yields $\mathcal{QLE}> \frac{Q^{2}}{2R}$ for all constant radii membranes containing the horizon and in such case the charge factor appearing in the right-hand side exactly equals to that of Bekenstein's inequality. Moreover, we show that the total quasi-local energy monotonically decays from $2M_{irr}+V_{Q}$ ($M_{irr}$ is the irreducible mass, $V_{Q}$ is the electric potential energy) at the outer horizon to $M$ ($M$ is the ADM mass) at the space-like infinity under the assumption of a small angular momentum of the black hole. |
gr-qc/9307038 | Robert Manuel Wald | Robert M. Wald | Black Hole Entropy is Noether Charge | 16 pages, EFI 93-42 | Phys.Rev.D48:3427-3431,1993 | 10.1103/PhysRevD.48.R3427 | null | gr-qc | null | We consider a general, classical theory of gravity in $n$ dimensions, arising
from a diffeomorphism invariant Lagrangian. In any such theory, to each vector
field, $\xi^a$, on spacetime one can associate a local symmetry and, hence, a
Noether current $(n-1)$-form, ${\bf j}$, and (for solutions to the field
equations) a Noether charge $(n-2)$-form, ${\bf Q}$. Assuming only that the
theory admits stationary black hole solutions with a bifurcate Killing horizon,
and that the canonical mass and angular momentum of solutions are well defined
at infinity, we show that the first law of black hole mechanics always holds
for perturbations to nearby stationary black hole solutions. The quantity
playing the role of black hole entropy in this formula is simply $2 \pi$ times
the integral over $\Sigma$ of the Noether charge $(n-2)$-form associated with
the horizon Killing field, normalized so as to have unit surface gravity.
Furthermore, we show that this black hole entropy always is given by a local
geometrical expression on the horizon of the black hole. We thereby obtain a
natural candidate for the entropy of a dynamical black hole in a general theory
of gravity. Our results show that the validity of the ``second law" of black
hole mechanics in dynamical evolution from an initially stationary black hole
to a final stationary state is equivalent to the positivity of a total Noether
flux, and thus may be intimately related to the positive energy properties of
the theory. The relationship between the derivation of our formula for black
hole entropy and the derivation via ``Euclidean methods" also is explained.
| [
{
"created": "Thu, 29 Jul 1993 16:37:13 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Wald",
"Robert M.",
""
]
] | We consider a general, classical theory of gravity in $n$ dimensions, arising from a diffeomorphism invariant Lagrangian. In any such theory, to each vector field, $\xi^a$, on spacetime one can associate a local symmetry and, hence, a Noether current $(n-1)$-form, ${\bf j}$, and (for solutions to the field equations) a Noether charge $(n-2)$-form, ${\bf Q}$. Assuming only that the theory admits stationary black hole solutions with a bifurcate Killing horizon, and that the canonical mass and angular momentum of solutions are well defined at infinity, we show that the first law of black hole mechanics always holds for perturbations to nearby stationary black hole solutions. The quantity playing the role of black hole entropy in this formula is simply $2 \pi$ times the integral over $\Sigma$ of the Noether charge $(n-2)$-form associated with the horizon Killing field, normalized so as to have unit surface gravity. Furthermore, we show that this black hole entropy always is given by a local geometrical expression on the horizon of the black hole. We thereby obtain a natural candidate for the entropy of a dynamical black hole in a general theory of gravity. Our results show that the validity of the ``second law" of black hole mechanics in dynamical evolution from an initially stationary black hole to a final stationary state is equivalent to the positivity of a total Noether flux, and thus may be intimately related to the positive energy properties of the theory. The relationship between the derivation of our formula for black hole entropy and the derivation via ``Euclidean methods" also is explained. |
1903.05203 | Blake Moore | Blake Moore and Nicol\'as Yunes | A 3PN Fourier Domain Waveform for Non-Spinning Binaries with Moderate
Eccentricity | null | null | 10.1088/1361-6382/ab3778 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | While current gravitational wave observations with ground based detectors
have been consistent with compact binaries in quasi-circular orbits, eccentric
binaries may be detectable by ground-based and space-based instruments in the
near future. Eccentricity significantly complicates the gravitational wave
signal, and we currently lack fast and accurate models that are valid in the
moderate to large eccentricity range. In a previous paper, we built a Fourier
domain, eccentric waveform model at leading order in the post-Newtonian
approximation, i.e. as an expansion in small velocities and weak fields. Here
we extend this model to 3rd post-Newtonian order, incorporating the effects of
periastron precession and higher post-Newtonian order effects that
qualitatively change the waveform behavior. Our 3PN model combines the
stationary phase approximation, a truncated sum of harmonics of combinations of
two orbital frequencies (an azimuthal one and a radial one), and a bivariate
expansion in the orbital separation and the eccentricity. We validate the model
through comparisons with a fully-numerical, time domain post-Newtonian model,
and find good agreement (matches between $97\% - 99\%$) in much of the
parameter space. We estimate in what regions of parameter space eccentric
effects are important by exploring the signal to noise ratio of eccentric
corrections. We also examine the effects of higher post-Newtonian order terms
in the waveform amplitude, and the agreement between different PN-consistent,
numerical, time-domain models. In an effort to guide future improvements to the
model, we gauge the error in our 3PN model incurred by the different analytic
approximations used to construct it. This model is useful for preliminary data
analysis investigations and it could allow for a phenomenological hybrid that
incorporates eccentricity into an inspiral-merger-ringdown model.
| [
{
"created": "Tue, 12 Mar 2019 20:43:10 GMT",
"version": "v1"
}
] | 2019-09-04 | [
[
"Moore",
"Blake",
""
],
[
"Yunes",
"Nicolás",
""
]
] | While current gravitational wave observations with ground based detectors have been consistent with compact binaries in quasi-circular orbits, eccentric binaries may be detectable by ground-based and space-based instruments in the near future. Eccentricity significantly complicates the gravitational wave signal, and we currently lack fast and accurate models that are valid in the moderate to large eccentricity range. In a previous paper, we built a Fourier domain, eccentric waveform model at leading order in the post-Newtonian approximation, i.e. as an expansion in small velocities and weak fields. Here we extend this model to 3rd post-Newtonian order, incorporating the effects of periastron precession and higher post-Newtonian order effects that qualitatively change the waveform behavior. Our 3PN model combines the stationary phase approximation, a truncated sum of harmonics of combinations of two orbital frequencies (an azimuthal one and a radial one), and a bivariate expansion in the orbital separation and the eccentricity. We validate the model through comparisons with a fully-numerical, time domain post-Newtonian model, and find good agreement (matches between $97\% - 99\%$) in much of the parameter space. We estimate in what regions of parameter space eccentric effects are important by exploring the signal to noise ratio of eccentric corrections. We also examine the effects of higher post-Newtonian order terms in the waveform amplitude, and the agreement between different PN-consistent, numerical, time-domain models. In an effort to guide future improvements to the model, we gauge the error in our 3PN model incurred by the different analytic approximations used to construct it. This model is useful for preliminary data analysis investigations and it could allow for a phenomenological hybrid that incorporates eccentricity into an inspiral-merger-ringdown model. |
1408.3334 | Hristu Culetu | Hristu Culetu | On a regular charged black hole with a nonlinear electric source | 11 pages, four figures, footnote updated, Int. J. Theor. Phys.
(2015), 54: 2855 - 2863 | null | 10.1007/s10773-015-2521-6 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A modified version of the Reissner-Nordstrom metric is proposed on the
grounds of the nonlinear electrodynamics model. The source of curvature is an
anisotropic fluid with $p_{r} = -\rho$ which resembles the Maxwell stress
tensor at $r >> q^{2}/2m$, where $q$ and $m$ are the mass and charge of the
particle, respectively. We found the black hole horizon entropy obeys the
relation $S = |W|/2T = A_{H}/4$, with $W$ the Komar energy and $A_{H}$ the
horizon area. The electric field around the source depends not only on its
charge but also on its mass. The corresponding electrostatic potential
$\Phi(r)$ is finite everywhere, vanishes at the origin and at $r = q^{2}/6m$
and is nonzero asymptotically, with $\Phi_{\infty} = 3m/2q$.
| [
{
"created": "Thu, 14 Aug 2014 16:37:59 GMT",
"version": "v1"
},
{
"created": "Sat, 30 Aug 2014 11:10:26 GMT",
"version": "v2"
},
{
"created": "Thu, 23 Apr 2015 16:42:55 GMT",
"version": "v3"
},
{
"created": "Fri, 30 Oct 2015 13:47:58 GMT",
"version": "v4"
}
] | 2015-11-02 | [
[
"Culetu",
"Hristu",
""
]
] | A modified version of the Reissner-Nordstrom metric is proposed on the grounds of the nonlinear electrodynamics model. The source of curvature is an anisotropic fluid with $p_{r} = -\rho$ which resembles the Maxwell stress tensor at $r >> q^{2}/2m$, where $q$ and $m$ are the mass and charge of the particle, respectively. We found the black hole horizon entropy obeys the relation $S = |W|/2T = A_{H}/4$, with $W$ the Komar energy and $A_{H}$ the horizon area. The electric field around the source depends not only on its charge but also on its mass. The corresponding electrostatic potential $\Phi(r)$ is finite everywhere, vanishes at the origin and at $r = q^{2}/6m$ and is nonzero asymptotically, with $\Phi_{\infty} = 3m/2q$. |
1511.06516 | Jun-Jin Peng | Jun-Jin Peng | Off-shell Noether current and conserved charge in Horndeski theory | 19 pages, no figures, to appear in PLB | null | 10.1016/j.physletb.2015.11.041 | null | gr-qc | http://creativecommons.org/licenses/by-nc-sa/4.0/ | We derive the off-shell Noether current and potential in the context of
Horndeski theory, which is the most general scalar-tensor theory with a
Lagrangian containing derivatives up to second order while yielding at most to
second-order equations of motion in four dimensions. Then the formulation of
conserved charges is proposed on basis of the off-shell Noether potential and
the surface term got from the variation of the Lagrangian. As an application,
we calculate the conserved charges of black holes in a scalar-tensor theory
with non-minimal coupling between derivatives of the scalar field and the
Einstein tensor.
| [
{
"created": "Fri, 20 Nov 2015 08:16:30 GMT",
"version": "v1"
}
] | 2016-01-20 | [
[
"Peng",
"Jun-Jin",
""
]
] | We derive the off-shell Noether current and potential in the context of Horndeski theory, which is the most general scalar-tensor theory with a Lagrangian containing derivatives up to second order while yielding at most to second-order equations of motion in four dimensions. Then the formulation of conserved charges is proposed on basis of the off-shell Noether potential and the surface term got from the variation of the Lagrangian. As an application, we calculate the conserved charges of black holes in a scalar-tensor theory with non-minimal coupling between derivatives of the scalar field and the Einstein tensor. |
1304.7766 | Gerald Marsh | Gerald E. Marsh | Space-Time-Matter | 44 pages; 7 figures. arXiv admin note: text overlap with
arXiv:0912.5099, arXiv:0809.1877. Revised and expanded | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This essay examines our fundamental conceptions of time, spacetime, the
asymmetry of time, and the motion of a quantum mechanical particle. The concept
of time has multiple meanings and these are often confused in the literature
and must be distinguished if any light is to be thrown on this age-old issue.
The asymmetry of time also has different meanings that depend on
context-although the fundamental time asymmetry is associated with the
expansion of the universe. These and related issues are discussed in both
classical and quantum mechanical contexts.
| [
{
"created": "Sun, 28 Apr 2013 18:14:10 GMT",
"version": "v1"
},
{
"created": "Sat, 4 May 2013 17:50:29 GMT",
"version": "v2"
},
{
"created": "Thu, 14 Aug 2014 16:08:26 GMT",
"version": "v3"
}
] | 2014-08-15 | [
[
"Marsh",
"Gerald E.",
""
]
] | This essay examines our fundamental conceptions of time, spacetime, the asymmetry of time, and the motion of a quantum mechanical particle. The concept of time has multiple meanings and these are often confused in the literature and must be distinguished if any light is to be thrown on this age-old issue. The asymmetry of time also has different meanings that depend on context-although the fundamental time asymmetry is associated with the expansion of the universe. These and related issues are discussed in both classical and quantum mechanical contexts. |
1308.1686 | Helvi Witek | Helvi Witek | Lecture Notes: Numerical Relativity in higher dimensional spacetimes | Lecture notes from the NRHEP spring school held at IST-Lisbon, March
2013. Matches published version in Int.J.Mod.Phys. A28 (2013) 1340017 | Int.J.Mod.Phys. A28 (2013) 1340017 | 10.1142/S0217751X13400174 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Black holes are among the most exciting phenomena predicted by General
Relativity and play a key role in fundamental physics. Many interesting
phenomena involve dynamical black hole configurations in the high curvature
regime of gravity. In these lecture notes I will summarise the main numerical
relativity techniques to explore highly dynamical phenomena, such as black hole
collisions, in generic $D$-dimensional spacetimes.
| [
{
"created": "Wed, 7 Aug 2013 20:04:49 GMT",
"version": "v1"
},
{
"created": "Thu, 10 Oct 2013 08:51:47 GMT",
"version": "v2"
}
] | 2013-10-11 | [
[
"Witek",
"Helvi",
""
]
] | Black holes are among the most exciting phenomena predicted by General Relativity and play a key role in fundamental physics. Many interesting phenomena involve dynamical black hole configurations in the high curvature regime of gravity. In these lecture notes I will summarise the main numerical relativity techniques to explore highly dynamical phenomena, such as black hole collisions, in generic $D$-dimensional spacetimes. |
1604.03673 | Dawood Kothawala Dr. | Dawood Kothawala | Accelerated Observers, Thermal Entropy, and Spacetime Curvature | Contribution to the Festschrift in honor of Professor T. Padmanabhan
on the occassion of his 60th birthday | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Assuming that an accelerated observer with four-velocity ${\bf u}_{\rm R}$ in
a curved spacetime attributes the standard Bekenstein-Hawking entropy and Unruh
temperature to his "local Rindler horizon", we show that the $\rm \it change$
in horizon area under parametric displacements of the horizon has a very
specific thermodynamic structure. Specifically, it entails information about
the time-time component of the Einstein tensor: $\bf G({\bf u}_{\rm R}, {\bf
u}_{\rm R})$. Demanding that the result holds for all accelerated observers,
this actually becomes a statement about the full Einstein tensor, $\rm \bf G$.
We also present some perspectives on the free fall with four-velocity ${\bf
u}_{\rm ff}$ across the horizon that leads to such a loss of entropy for an
accelerated observer. Motivated by results for some simple quantum systems at
finite temperature $T$, we conjecture that at high temperatures, there exists a
universal, system-independent curvature correction to partition function and
thermal entropy of $\rm \it any$ freely falling system, characterised by the
dimensional quantity $\Delta = {\bf R({\bf u}_{\rm ff}, {\bf u}_{\rm ff})}
\left(\hbar c/kT \right)^2$.
| [
{
"created": "Wed, 13 Apr 2016 06:51:35 GMT",
"version": "v1"
},
{
"created": "Mon, 20 Jun 2016 05:36:11 GMT",
"version": "v2"
}
] | 2016-06-21 | [
[
"Kothawala",
"Dawood",
""
]
] | Assuming that an accelerated observer with four-velocity ${\bf u}_{\rm R}$ in a curved spacetime attributes the standard Bekenstein-Hawking entropy and Unruh temperature to his "local Rindler horizon", we show that the $\rm \it change$ in horizon area under parametric displacements of the horizon has a very specific thermodynamic structure. Specifically, it entails information about the time-time component of the Einstein tensor: $\bf G({\bf u}_{\rm R}, {\bf u}_{\rm R})$. Demanding that the result holds for all accelerated observers, this actually becomes a statement about the full Einstein tensor, $\rm \bf G$. We also present some perspectives on the free fall with four-velocity ${\bf u}_{\rm ff}$ across the horizon that leads to such a loss of entropy for an accelerated observer. Motivated by results for some simple quantum systems at finite temperature $T$, we conjecture that at high temperatures, there exists a universal, system-independent curvature correction to partition function and thermal entropy of $\rm \it any$ freely falling system, characterised by the dimensional quantity $\Delta = {\bf R({\bf u}_{\rm ff}, {\bf u}_{\rm ff})} \left(\hbar c/kT \right)^2$. |
1101.4490 | Hemwati Nandan | Nils M. Bezares-Roder, Hemwati Nandan, Umananda Dev Goswami | Primeval acceleration and bounce conditions within induced gravity | 23 pages, 3 figures, Dedicated to 75th birth anniversary of Heinz
Dehnen | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A model of induced gravity with Higgs potential is analysed for the FLRW
cosmology. Conditions of acceleration and signatures for the primeval universe
along with the inflation are discussed. It is shown that the scalar-field
excitations act quintessentially within effective pressure terms for a negative
deceleration parameter. The violation of energy conditions and primeval
acceleration appears naturally in the present model in view of the notions for
inflationary universe with the avoidance of the Big Bang singularity.
| [
{
"created": "Mon, 24 Jan 2011 10:38:25 GMT",
"version": "v1"
}
] | 2015-03-17 | [
[
"Bezares-Roder",
"Nils M.",
""
],
[
"Nandan",
"Hemwati",
""
],
[
"Goswami",
"Umananda Dev",
""
]
] | A model of induced gravity with Higgs potential is analysed for the FLRW cosmology. Conditions of acceleration and signatures for the primeval universe along with the inflation are discussed. It is shown that the scalar-field excitations act quintessentially within effective pressure terms for a negative deceleration parameter. The violation of energy conditions and primeval acceleration appears naturally in the present model in view of the notions for inflationary universe with the avoidance of the Big Bang singularity. |
gr-qc/0606103 | Mohammad Reza Setare | M. R. Setare and S. Shafei | The Holographic Model of Dark Energy and Thermodynamics of Non-Flat
Accelerated Expanding Universe | 12 pages, no figure, abstract and text extended, references added,
accepted for publication in JCAP | JCAP 0609 (2006) 011 | 10.1088/1475-7516/2006/09/011 | null | gr-qc | null | Motivated by recent results on non-vanishing spatial curvature \cite{curve}
we employ the holographic model of dark energy to investigate the validity of
first and second laws of thermodynamics in non-flat (closed) universe enclosed
by apparent horizon $R_A$ and the event horizon measured from the sphere of
horizon named $L$. We show that for the apparent horizon the first law is
roughly respected for different epochs while the second laws of thermodynamics
is respected while for $L$ as the system's IR cut-off first law is broken down
and second law is respected for special range of deceleration parameter. It is
also shown that at late-time universe $L$ is equal to $R_A$ and the
thermodynamic laws are hold, when the universe has non-vanishing curvature.
Defining the fluid temperature to be proportional to horizon temperature the
range for coefficient of proportionality is obtained provided that the
generalized second law of thermodynamics is hold.
| [
{
"created": "Fri, 23 Jun 2006 14:03:12 GMT",
"version": "v1"
},
{
"created": "Thu, 31 Aug 2006 11:15:58 GMT",
"version": "v2"
},
{
"created": "Sat, 14 Oct 2006 12:04:26 GMT",
"version": "v3"
}
] | 2009-11-11 | [
[
"Setare",
"M. R.",
""
],
[
"Shafei",
"S.",
""
]
] | Motivated by recent results on non-vanishing spatial curvature \cite{curve} we employ the holographic model of dark energy to investigate the validity of first and second laws of thermodynamics in non-flat (closed) universe enclosed by apparent horizon $R_A$ and the event horizon measured from the sphere of horizon named $L$. We show that for the apparent horizon the first law is roughly respected for different epochs while the second laws of thermodynamics is respected while for $L$ as the system's IR cut-off first law is broken down and second law is respected for special range of deceleration parameter. It is also shown that at late-time universe $L$ is equal to $R_A$ and the thermodynamic laws are hold, when the universe has non-vanishing curvature. Defining the fluid temperature to be proportional to horizon temperature the range for coefficient of proportionality is obtained provided that the generalized second law of thermodynamics is hold. |
0711.0714 | Arundhati Dasgupta | Arundhati Dasgupta | Semiclassical Horizons | 9pgs, Talk at Theory Canada III, to appear in CJP | null | 10.1139/P07-189 | null | gr-qc | null | The entropy of apparent horizons is derived using coherent states or
semiclassical states in quantum gravity. The leading term is proportional to
area for large horizons, and the correction terms differ according to the
details of the graph which is used to regularise the quantum gravity phase
space variables.
| [
{
"created": "Mon, 5 Nov 2007 18:28:30 GMT",
"version": "v1"
}
] | 2009-11-13 | [
[
"Dasgupta",
"Arundhati",
""
]
] | The entropy of apparent horizons is derived using coherent states or semiclassical states in quantum gravity. The leading term is proportional to area for large horizons, and the correction terms differ according to the details of the graph which is used to regularise the quantum gravity phase space variables. |
1810.01460 | Bobur Turimov | Bobur Turimov, Bobomurat Ahmedov, Martin Kolo\v{s}, Zden\v{e}k
Stuchl\'ik | Axially symmetric and static solutions of Einstein equations with
self-gravitating scalar field | 16 pages, 9 figures | published in Phys. Rev. D, (2018) | 10.1103/PhysRevD.98.084039 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The exact axisymmetric and static solution of the Einstein equations coupled
to axisymmetric and static gravitating scalar (or phantom) field is presented.
The spacetimes modified by the scalar field are explicitly given for the so
called $\gamma$-metric and Erez-Rosen metric with quadrupole moment $q$,
influence of the additional deformation parameters $\gamma_*$ and $q_*$
generated by the scalar field is studied. It is shown that the null energy
condition is satisfied for the phantom field, but it is not satisfied for the
standard scalar field. The test particle motion in the both modified
$\gamma$-metric and Erez-Rosen quadrupole metric is studied; the circular
geodesics are determined, and near-circular trajectories are explicitly
presented for characteristic values of the spacetime parameters. It is also
demonstrated that the parameters $\gamma_*$ and $q_*$ have no influence on the
test particle motion in the equatorial plane.
| [
{
"created": "Tue, 2 Oct 2018 19:15:57 GMT",
"version": "v1"
},
{
"created": "Thu, 8 Nov 2018 07:01:19 GMT",
"version": "v2"
}
] | 2018-11-09 | [
[
"Turimov",
"Bobur",
""
],
[
"Ahmedov",
"Bobomurat",
""
],
[
"Kološ",
"Martin",
""
],
[
"Stuchlík",
"Zdeněk",
""
]
] | The exact axisymmetric and static solution of the Einstein equations coupled to axisymmetric and static gravitating scalar (or phantom) field is presented. The spacetimes modified by the scalar field are explicitly given for the so called $\gamma$-metric and Erez-Rosen metric with quadrupole moment $q$, influence of the additional deformation parameters $\gamma_*$ and $q_*$ generated by the scalar field is studied. It is shown that the null energy condition is satisfied for the phantom field, but it is not satisfied for the standard scalar field. The test particle motion in the both modified $\gamma$-metric and Erez-Rosen quadrupole metric is studied; the circular geodesics are determined, and near-circular trajectories are explicitly presented for characteristic values of the spacetime parameters. It is also demonstrated that the parameters $\gamma_*$ and $q_*$ have no influence on the test particle motion in the equatorial plane. |
gr-qc/0404126 | Nathalie Deruelle | Nathalie Deruelle | Bouncing universes and their perturbations: remarks on a toy model | null | null | null | null | gr-qc astro-ph hep-th | null | Friedmann-Lemaitre universes driven by a scalar field, spatially closed and
bouncing, were recently studied by Martin and Peter in [1], with the conclusion
that the spectrum of their large scale matter perturbations was generically
modified when going through the bounce. In this Note we give the properties of
the scalar field potentials which underly such models.
| [
{
"created": "Fri, 30 Apr 2004 10:06:28 GMT",
"version": "v1"
},
{
"created": "Wed, 16 Jun 2004 15:22:33 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Deruelle",
"Nathalie",
""
]
] | Friedmann-Lemaitre universes driven by a scalar field, spatially closed and bouncing, were recently studied by Martin and Peter in [1], with the conclusion that the spectrum of their large scale matter perturbations was generically modified when going through the bounce. In this Note we give the properties of the scalar field potentials which underly such models. |
1606.06531 | Liu Zhao | Yuan Sun, Hao Xu and Liu Zhao | Thermodynamics and holographic entanglement entropy for spherical black
holes in 5D Gauss-Bonnet gravity | 17 pages, 4 PDF figures. Update: journal version | JHEP 09 (2016) 060 | 10.1007/JHEP09(2016)060 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The holographic entanglement entropy is studied numerically in
(4+1)-dimensional spherically symmetric Gauss-Bonnet AdS black hole spacetime
with compact boundary. On the bulk side the black hole spacetime undergoes a
van der Waals-like phase transition in the extended phase space, which is
reviewed with emphasis on the behavior on the temperature-entropy plane. On the
boundary, we calculated the regularized HEE of a disk region of different
sizes. We find strong numerical evidence for the failure of equal area law for
isobaric curves on the temperature-HEE plane and for the correctness of first
law of entanglement entropy, and briefly give an explanation for why the latter
may serve as a reason for the former, i.e. the failure of equal area law on the
temperature-HEE plane.
| [
{
"created": "Tue, 21 Jun 2016 12:17:43 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Sep 2016 04:53:23 GMT",
"version": "v2"
}
] | 2016-10-12 | [
[
"Sun",
"Yuan",
""
],
[
"Xu",
"Hao",
""
],
[
"Zhao",
"Liu",
""
]
] | The holographic entanglement entropy is studied numerically in (4+1)-dimensional spherically symmetric Gauss-Bonnet AdS black hole spacetime with compact boundary. On the bulk side the black hole spacetime undergoes a van der Waals-like phase transition in the extended phase space, which is reviewed with emphasis on the behavior on the temperature-entropy plane. On the boundary, we calculated the regularized HEE of a disk region of different sizes. We find strong numerical evidence for the failure of equal area law for isobaric curves on the temperature-HEE plane and for the correctness of first law of entanglement entropy, and briefly give an explanation for why the latter may serve as a reason for the former, i.e. the failure of equal area law on the temperature-HEE plane. |
1103.4078 | Geoffrey Comp\`ere | Geoffrey Comp\`ere, Fran\c{c}ois Dehouck and Amitabh Virmani | On Asymptotic Flatness and Lorentz Charges | 26 pages; no figures; v2: minor changes; v3: clarifications +
references + a new lemma added, results unaffected | null | 10.1088/0264-9381/28/14/145007 | ULB-TH/11-08 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we establish two results concerning four-dimensional
asymptotically flat spacetimes at spatial infinity. First, we show that the six
conserved Lorentz charges are encoded in two unique, distinct, but mutually
dual symmetric divergence free tensors that we construct from the equations of
motion. Second, we show that integrability of Einstein's equations in the
asymptotic expansion is sufficient to establish the equivalence between
counter-term charges defined from the variational principle and charges defined
by Ashtekar and Hansen. These results clarify earlier constructions of
conserved charges in the hyperboloid representation of spatial infinity. In
showing this, parity condition on the mass aspect is not needed. Along the way
in establishing these results, we prove two lemmae on tensor fields on three
dimensional de Sitter spacetime stated by Ashtekar-Hansen and Beig-Schmidt and
state and prove three additional lemmae.
| [
{
"created": "Mon, 21 Mar 2011 17:01:31 GMT",
"version": "v1"
},
{
"created": "Mon, 28 Mar 2011 18:23:38 GMT",
"version": "v2"
},
{
"created": "Thu, 14 Apr 2011 13:23:16 GMT",
"version": "v3"
}
] | 2015-05-27 | [
[
"Compère",
"Geoffrey",
""
],
[
"Dehouck",
"François",
""
],
[
"Virmani",
"Amitabh",
""
]
] | In this paper we establish two results concerning four-dimensional asymptotically flat spacetimes at spatial infinity. First, we show that the six conserved Lorentz charges are encoded in two unique, distinct, but mutually dual symmetric divergence free tensors that we construct from the equations of motion. Second, we show that integrability of Einstein's equations in the asymptotic expansion is sufficient to establish the equivalence between counter-term charges defined from the variational principle and charges defined by Ashtekar and Hansen. These results clarify earlier constructions of conserved charges in the hyperboloid representation of spatial infinity. In showing this, parity condition on the mass aspect is not needed. Along the way in establishing these results, we prove two lemmae on tensor fields on three dimensional de Sitter spacetime stated by Ashtekar-Hansen and Beig-Schmidt and state and prove three additional lemmae. |
1102.5759 | Razvan-Gheorghe Gurau | Razvan Gurau | The complete 1/N expansion of colored tensor models in arbitrary
dimension | null | null | 10.1007/s00023-011-0118-z | pi-qg-214 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we generalize the results of [1,2] and derive the full 1/N
expansion of colored tensor models in arbitrary dimensions. We detail the
expansion for the independent identically distributed model and the topological
Boulatov Ooguri model.
| [
{
"created": "Mon, 28 Feb 2011 20:09:46 GMT",
"version": "v1"
}
] | 2015-05-27 | [
[
"Gurau",
"Razvan",
""
]
] | In this paper we generalize the results of [1,2] and derive the full 1/N expansion of colored tensor models in arbitrary dimensions. We detail the expansion for the independent identically distributed model and the topological Boulatov Ooguri model. |
1604.03604 | Alexander Zhidenko | M. A. Cuyubamba, R. A. Konoplya, A. Zhidenko | Quasinormal modes and a new instability of Einstein-Gauss-Bonnet black
holes in the de Sitter world | 9 pages, 8 figures | Phys. Rev. D 93, 104053 (2016) | 10.1103/PhysRevD.93.104053 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Analysis of time-domain profiles for gravitational perturbations shows that
Gauss-Bonnet black holes in a de Sitter world possess a new kind of dynamical
instability which does not take place for asymptotically flat
Einstein-Gauss-Bonnet black holes. The new instability is in the gravitational
perturbations of the scalar type and is due to the nonvanishing cosmological
constant. Analysis of the quasinormal spectrum in the stability sector shows
that although the scalar type of gravitational perturbations alone does not
obey Hod's conjectural bound, connecting the damping rate and the Hawking
temperature, the vector and tensor types (and thereby the gravitational
spectrum as a whole) do obey it.
| [
{
"created": "Tue, 12 Apr 2016 22:11:38 GMT",
"version": "v1"
},
{
"created": "Fri, 20 May 2016 16:24:41 GMT",
"version": "v2"
}
] | 2016-05-30 | [
[
"Cuyubamba",
"M. A.",
""
],
[
"Konoplya",
"R. A.",
""
],
[
"Zhidenko",
"A.",
""
]
] | Analysis of time-domain profiles for gravitational perturbations shows that Gauss-Bonnet black holes in a de Sitter world possess a new kind of dynamical instability which does not take place for asymptotically flat Einstein-Gauss-Bonnet black holes. The new instability is in the gravitational perturbations of the scalar type and is due to the nonvanishing cosmological constant. Analysis of the quasinormal spectrum in the stability sector shows that although the scalar type of gravitational perturbations alone does not obey Hod's conjectural bound, connecting the damping rate and the Hawking temperature, the vector and tensor types (and thereby the gravitational spectrum as a whole) do obey it. |
2311.12645 | Yu-Min Hu | Yu-Min Hu, Yang Yu, Yi-Fu Cai, Xian Gao | The effective field theory approach to the strong coupling issue in
$f(T)$ gravity with a non-minimally coupled scalar field | null | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Hamiltonian analysis for $f(T)$ gravity implies the existence of at least
one scalar-type degree of freedom (DoF). However, this scalar DoF of $f(T)$
gravity does not manifest in linear perturbations around a cosmological
background, which indicates an underlying strong coupling problem. In this work
we expand the scope by introducing an extra scalar field non-minimally coupled
to $f(T)$ gravity, aiming to address or alleviate the aforementioned strong
coupling problem. Employing the effective field theory (EFT) approach, we
provide a class of torsional EFT forms up to second order operators, avoiding
the Ostrogradsky ghost. To illustrate this phenomenon, we study a simple model
and perform a detailed analysis of its linear scalar perturbations. The results
demonstrate that the coupling terms in this toy model are necessary to avoid
the initial degenerate situation. The complete avoidance of new constraints
requires more coupling terms. Once this vanishing scalar DoF starts propagating
in cosmological background at linear level, this phenomenon will demand a
revisit of the strong coupling issue that arises in $f(T)$ gravity,
particularly in the presence of matter coupling.
| [
{
"created": "Tue, 21 Nov 2023 14:45:39 GMT",
"version": "v1"
},
{
"created": "Wed, 31 Jan 2024 11:42:01 GMT",
"version": "v2"
}
] | 2024-02-01 | [
[
"Hu",
"Yu-Min",
""
],
[
"Yu",
"Yang",
""
],
[
"Cai",
"Yi-Fu",
""
],
[
"Gao",
"Xian",
""
]
] | The Hamiltonian analysis for $f(T)$ gravity implies the existence of at least one scalar-type degree of freedom (DoF). However, this scalar DoF of $f(T)$ gravity does not manifest in linear perturbations around a cosmological background, which indicates an underlying strong coupling problem. In this work we expand the scope by introducing an extra scalar field non-minimally coupled to $f(T)$ gravity, aiming to address or alleviate the aforementioned strong coupling problem. Employing the effective field theory (EFT) approach, we provide a class of torsional EFT forms up to second order operators, avoiding the Ostrogradsky ghost. To illustrate this phenomenon, we study a simple model and perform a detailed analysis of its linear scalar perturbations. The results demonstrate that the coupling terms in this toy model are necessary to avoid the initial degenerate situation. The complete avoidance of new constraints requires more coupling terms. Once this vanishing scalar DoF starts propagating in cosmological background at linear level, this phenomenon will demand a revisit of the strong coupling issue that arises in $f(T)$ gravity, particularly in the presence of matter coupling. |
1703.08454 | Astrid Eichhorn | Astrid Eichhorn, Sebastian Mizera and Sumati Surya | Echoes of Asymptotic Silence in Causal Set Quantum Gravity | 12 pages, 7 figures | null | 10.1088/1361-6382/aa7d1b | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We explore the idea of asymptotic silence in causal set theory and find that
causal sets approximated by continuum spacetimes exhibit behaviour akin to
asymptotic silence. We make use of an intrinsic definition of spatial distance
between causal set elements in the discrete analogue of a spatial hypersurface.
Using numerical simulations for causal sets approximated by D=2,3 and 4
dimensional Minkowski spacetime, we show that while the discrete distance
rapidly converges to the continuum distance at a scale roughly an order of
magnitude larger than the discreteness scale, it is significantly larger on
small scales. This allows us to define an effective dimension which exhibits
dimensional reduction in the ultraviolet, while monotonically increasing to the
continuum dimension with increasing continuum distance. We interpret these
findings as manifestations of asymptotic silence in causal set theory.
| [
{
"created": "Fri, 24 Mar 2017 15:12:31 GMT",
"version": "v1"
}
] | 2017-08-02 | [
[
"Eichhorn",
"Astrid",
""
],
[
"Mizera",
"Sebastian",
""
],
[
"Surya",
"Sumati",
""
]
] | We explore the idea of asymptotic silence in causal set theory and find that causal sets approximated by continuum spacetimes exhibit behaviour akin to asymptotic silence. We make use of an intrinsic definition of spatial distance between causal set elements in the discrete analogue of a spatial hypersurface. Using numerical simulations for causal sets approximated by D=2,3 and 4 dimensional Minkowski spacetime, we show that while the discrete distance rapidly converges to the continuum distance at a scale roughly an order of magnitude larger than the discreteness scale, it is significantly larger on small scales. This allows us to define an effective dimension which exhibits dimensional reduction in the ultraviolet, while monotonically increasing to the continuum dimension with increasing continuum distance. We interpret these findings as manifestations of asymptotic silence in causal set theory. |
gr-qc/0505071 | Bernd Schroers | C Meusburger, B J Schroers | Boundary conditions and symplectic structure in the Chern-Simons
formulation of (2+1)-dimensional gravity | 44 pages, 3 eps figures | Class.Quant.Grav. 22 (2005) 3689-3724 | 10.1088/0264-9381/22/17/021 | EMPG-05-08 | gr-qc | null | We propose a description of open universes in the Chern-Simons formulation of
(2+1)-dimensional gravity where spatial infinity is implemented as a puncture.
At this puncture, additional variables are introduced which lie in the
cotangent bundle of the Poincar\'e group, and coupled minimally to the
Chern-Simons gauge field. We apply this description of spatial infinity to open
universes of general genus and with an arbitrary number of massive spinning
particles. Using results of [9] we give a finite dimensional description of the
phase space and determine its symplectic structure. In the special case of a
genus zero universe with spinless particles, we compare our result to the
symplectic structure computed by Matschull in the metric formulation of
(2+1)-dimensional gravity. We comment on the quantisation of the phase space
and derive a quantisation condition for the total mass and spin of an open
universe.
| [
{
"created": "Mon, 16 May 2005 20:05:13 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Meusburger",
"C",
""
],
[
"Schroers",
"B J",
""
]
] | We propose a description of open universes in the Chern-Simons formulation of (2+1)-dimensional gravity where spatial infinity is implemented as a puncture. At this puncture, additional variables are introduced which lie in the cotangent bundle of the Poincar\'e group, and coupled minimally to the Chern-Simons gauge field. We apply this description of spatial infinity to open universes of general genus and with an arbitrary number of massive spinning particles. Using results of [9] we give a finite dimensional description of the phase space and determine its symplectic structure. In the special case of a genus zero universe with spinless particles, we compare our result to the symplectic structure computed by Matschull in the metric formulation of (2+1)-dimensional gravity. We comment on the quantisation of the phase space and derive a quantisation condition for the total mass and spin of an open universe. |
2002.09448 | Elizabeth Winstanley | Visakan Balakumar and Elizabeth Winstanley | Hadamard parametrix of the Feynman Green's function of a
five-dimensional charged scalar field | 27 pages, very minor changes, accepted for publication in the
Proceedings of the V Amazonian Symposium on Physics, 18-22 November 2019,
Belem, Brazil | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Hadamard parametrix is a representation of the short-distance singularity
structure of the Feynman Green's function for a quantum field on a curved
space-time background. Subtracting these divergent terms regularizes the
Feynman Green's function and enables the computation of renormalized
expectation values of observables. We study the Hadamard parametrix for a
charged, massive, complex scalar field in five space-time dimensions. Even in
Minkowski space-time, it is not possible to write the Feynman Green's function
for a charged scalar field exactly in closed form. We therefore present
covariant Taylor series expansions for the biscalars arising in the Hadamard
parametrix. On a general space-time background, we explicitly state the
expansion coefficients up to the order required for the computation of the
renormalized scalar field current. These coefficients become increasingly
lengthy as the order of the expansion increases, so we give the higher-order
terms required for the calculation of the renormalized stress-energy tensor in
Minkowski space-time only.
| [
{
"created": "Fri, 21 Feb 2020 18:04:40 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Jul 2020 18:00:31 GMT",
"version": "v2"
}
] | 2020-07-08 | [
[
"Balakumar",
"Visakan",
""
],
[
"Winstanley",
"Elizabeth",
""
]
] | The Hadamard parametrix is a representation of the short-distance singularity structure of the Feynman Green's function for a quantum field on a curved space-time background. Subtracting these divergent terms regularizes the Feynman Green's function and enables the computation of renormalized expectation values of observables. We study the Hadamard parametrix for a charged, massive, complex scalar field in five space-time dimensions. Even in Minkowski space-time, it is not possible to write the Feynman Green's function for a charged scalar field exactly in closed form. We therefore present covariant Taylor series expansions for the biscalars arising in the Hadamard parametrix. On a general space-time background, we explicitly state the expansion coefficients up to the order required for the computation of the renormalized scalar field current. These coefficients become increasingly lengthy as the order of the expansion increases, so we give the higher-order terms required for the calculation of the renormalized stress-energy tensor in Minkowski space-time only. |
1707.05192 | C. J. Pethick | Gordon Baym, Subodh P. Patil, and C. J. Pethick | Damping of gravitational waves by matter | 9 pages (10 pages in journal), published version | Physical Review D 96, 084033 (2017) | 10.1103/PhysRevD.96.084033 | NORDITA 2017-069 | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We develop a unified description, via the Boltzmann equation, of damping of
gravitational waves by matter, incorporating collisions. We identify two
physically distinct damping mechanisms -- collisional and Landau damping. We
first consider damping in flat spacetime, and then generalize the results to
allow for cosmological expansion. In the first regime, maximal collisional
damping of a gravitational wave, independent of the details of the collisions
in the matter is, as we show, significant only when its wavelength is
comparable to the size of the horizon. Thus damping by intergalactic or
interstellar matter for all but primordial gravitational radiation can be
neglected. Although collisions in matter lead to a shear viscosity, they also
act to erase anisotropic stresses, thus suppressing the damping of
gravitational waves. Damping of primordial gravitational waves remains
possible. We generalize Weinberg's calculation of gravitational wave damping,
now including collisions and particles of finite mass, and interpret the
collisionless limit in terms of Landau damping. While Landau damping of
gravitational waves cannot occur in flat spacetime, the expansion of the
universe allows such damping by spreading the frequency of a gravitational wave
of given wavevector.
| [
{
"created": "Fri, 14 Jul 2017 14:44:00 GMT",
"version": "v1"
},
{
"created": "Tue, 17 Oct 2017 12:50:28 GMT",
"version": "v2"
}
] | 2017-10-25 | [
[
"Baym",
"Gordon",
""
],
[
"Patil",
"Subodh P.",
""
],
[
"Pethick",
"C. J.",
""
]
] | We develop a unified description, via the Boltzmann equation, of damping of gravitational waves by matter, incorporating collisions. We identify two physically distinct damping mechanisms -- collisional and Landau damping. We first consider damping in flat spacetime, and then generalize the results to allow for cosmological expansion. In the first regime, maximal collisional damping of a gravitational wave, independent of the details of the collisions in the matter is, as we show, significant only when its wavelength is comparable to the size of the horizon. Thus damping by intergalactic or interstellar matter for all but primordial gravitational radiation can be neglected. Although collisions in matter lead to a shear viscosity, they also act to erase anisotropic stresses, thus suppressing the damping of gravitational waves. Damping of primordial gravitational waves remains possible. We generalize Weinberg's calculation of gravitational wave damping, now including collisions and particles of finite mass, and interpret the collisionless limit in terms of Landau damping. While Landau damping of gravitational waves cannot occur in flat spacetime, the expansion of the universe allows such damping by spreading the frequency of a gravitational wave of given wavevector. |
1401.0866 | Francisco Frutos-Alfaro Dr. rer. nat. | Francisco Frutos-Alfaro | Perturbation of the Kerr Metric | null | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A new Kerr-like metric with quadrupole moment is obtained by means of
perturbing the Kerr spacetime. By comparison with the exterior Hartle-Thorne
metric, it is showed that it could be matched to an interior solution. This
metric may represent the spacetime of an astrophysical object.
| [
{
"created": "Sun, 5 Jan 2014 04:11:24 GMT",
"version": "v1"
}
] | 2014-01-09 | [
[
"Frutos-Alfaro",
"Francisco",
""
]
] | A new Kerr-like metric with quadrupole moment is obtained by means of perturbing the Kerr spacetime. By comparison with the exterior Hartle-Thorne metric, it is showed that it could be matched to an interior solution. This metric may represent the spacetime of an astrophysical object. |
1312.1466 | Sarfraz Ali | M. Jamil Amir, Sarfraz Ali | Ricci Dark Energy of Amended FRW Universe in Chern-Simon Modified
Gravity | 11 pages,2 graphs. arXiv admin note: text overlap with
arXiv:0909.1267 by other authors without attribution | Int. J. Theor. Phys. (2015) | 10.1007/s10773-014-2334-z | 54:1362--1369 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The energy density of the universe is proportional to the Ricci scalar
curvature in the dynamical Chern-Simon (CS) modified gravity. In this paper, we
consider the Amended Friedman-Robertson-Walker (AFRW) universe and explore its
scale factor and the Ricci Dark Energy. THese turned out to be well-defined and
definite. We compare the scale factors of FRW \cite{[17]}, Generalized
Chaplygin gas (GCG) \cite{[18]} and AFRW models graphically. The combined graph
of these models show that the behavior of both FRW and AFRW models is similar
as these overlap each other for choosing particular values of the integration
constants. Also, we draw a combined graph of the Ricci dark energy densities of
FRW and AFRW models, in CS gravity, and the energy density of GCG. It shows
that the densities of former two models are increasing with time while the
energy density of GCG is decreasing.
| [
{
"created": "Thu, 5 Dec 2013 08:24:16 GMT",
"version": "v1"
}
] | 2015-09-21 | [
[
"Amir",
"M. Jamil",
""
],
[
"Ali",
"Sarfraz",
""
]
] | The energy density of the universe is proportional to the Ricci scalar curvature in the dynamical Chern-Simon (CS) modified gravity. In this paper, we consider the Amended Friedman-Robertson-Walker (AFRW) universe and explore its scale factor and the Ricci Dark Energy. THese turned out to be well-defined and definite. We compare the scale factors of FRW \cite{[17]}, Generalized Chaplygin gas (GCG) \cite{[18]} and AFRW models graphically. The combined graph of these models show that the behavior of both FRW and AFRW models is similar as these overlap each other for choosing particular values of the integration constants. Also, we draw a combined graph of the Ricci dark energy densities of FRW and AFRW models, in CS gravity, and the energy density of GCG. It shows that the densities of former two models are increasing with time while the energy density of GCG is decreasing. |
1108.5767 | Jan Hlad\'ik | Zdenek Stuchlik, Jan Hladik, Martin Urbanec | Neutrino trapping in braneworld extremely compact stars | null | null | 10.1007/s10714-011-1229-z | null | gr-qc astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Extremely Compact Stars (ECS) contain trapped null geodesics. When such
objects enter the evolution period admitting geodetical motion of neutrinos,
certain part of neutrinos produced in their interior will be trapped
influencing their neutrino luminosity and thermal evolution. We study neutrino
trapping in the braneworld ECS, assuming uniform distribution of neutrino
emissivity and massless neutrinos. We give the efficiency of the neutrino
trapping effects in the framework of the simple model of the internal spacetime
with uniform distribution of energy density, and external spacetime described
by the Reissner-Nordstr\"om geometry characterized by the braneworld "tidal"
parameter $b$. For $b < 0$ the external spacetime is of the black-hole type,
while for $b > 0$ the external spacetime can be of both black-hole and
naked-singularity type. Then the ECS surface radius $R$ can be located also
above the unstable (outer) photon circular orbit. Such basically new types of
the spacetimes strongly alter the trapping phenomena as compared to the
standard case of $b = 0$. It is shown that the neutrino trapping effects are
slightly lowered by the presence of physically more plausible case of $b < 0$,
as compared to the standard internal Schwarzschild spacetime, while they can be
magnified by positive tidal charges if $b < 1$ and lowered for $b > 1$.
However, potential astrophysical relevance of the trapping phenomena is
strongly enhanced for negative tidal charges enabling a significant enlargement
of the ECS surface radius to values coherent with recent observations.
| [
{
"created": "Mon, 29 Aug 2011 21:50:16 GMT",
"version": "v1"
}
] | 2011-08-31 | [
[
"Stuchlik",
"Zdenek",
""
],
[
"Hladik",
"Jan",
""
],
[
"Urbanec",
"Martin",
""
]
] | Extremely Compact Stars (ECS) contain trapped null geodesics. When such objects enter the evolution period admitting geodetical motion of neutrinos, certain part of neutrinos produced in their interior will be trapped influencing their neutrino luminosity and thermal evolution. We study neutrino trapping in the braneworld ECS, assuming uniform distribution of neutrino emissivity and massless neutrinos. We give the efficiency of the neutrino trapping effects in the framework of the simple model of the internal spacetime with uniform distribution of energy density, and external spacetime described by the Reissner-Nordstr\"om geometry characterized by the braneworld "tidal" parameter $b$. For $b < 0$ the external spacetime is of the black-hole type, while for $b > 0$ the external spacetime can be of both black-hole and naked-singularity type. Then the ECS surface radius $R$ can be located also above the unstable (outer) photon circular orbit. Such basically new types of the spacetimes strongly alter the trapping phenomena as compared to the standard case of $b = 0$. It is shown that the neutrino trapping effects are slightly lowered by the presence of physically more plausible case of $b < 0$, as compared to the standard internal Schwarzschild spacetime, while they can be magnified by positive tidal charges if $b < 1$ and lowered for $b > 1$. However, potential astrophysical relevance of the trapping phenomena is strongly enhanced for negative tidal charges enabling a significant enlargement of the ECS surface radius to values coherent with recent observations. |
2406.05177 | Fabian Gittins | Fabian Gittins, Nils Andersson | Neutron-star seismology with realistic, finite-temperature nuclear
matter | 14 pages, 6 figures, 1 table | null | null | null | gr-qc astro-ph.HE nucl-th | http://creativecommons.org/licenses/by/4.0/ | The oscillation spectrum of a neutron star is notably rich and intrinsically
dependent on the equation of state of nuclear matter. With recent advancements
in gravitational-wave and electromagnetic astronomy, we are nearing the
capability to perform neutron-star asteroseismology and probe the complex
physics of neutron stars. With this in mind, we explore the implementation of
three-parameter finite-temperature matter models in the computation of
neutron-star oscillations. We consider in detail the thermodynamics of nuclear
matter and show how this information enters the problem. Our realistic
treatment takes into account entropy and composition gradients that exist in
the nuclear matter, giving rise to buoyant g-mode oscillations. To illustrate
the implementation, we determine the oscillation spectrum of a low-temperature
neutron star. In addition to the expected compositional and thermal g-modes, we
find perturbations sourced by phase transitions in the equation of state. We
also examine the thermal evolution of the oscillation spectrum of a neutron
star with constant redshifted temperature.
| [
{
"created": "Fri, 7 Jun 2024 18:00:00 GMT",
"version": "v1"
}
] | 2024-06-11 | [
[
"Gittins",
"Fabian",
""
],
[
"Andersson",
"Nils",
""
]
] | The oscillation spectrum of a neutron star is notably rich and intrinsically dependent on the equation of state of nuclear matter. With recent advancements in gravitational-wave and electromagnetic astronomy, we are nearing the capability to perform neutron-star asteroseismology and probe the complex physics of neutron stars. With this in mind, we explore the implementation of three-parameter finite-temperature matter models in the computation of neutron-star oscillations. We consider in detail the thermodynamics of nuclear matter and show how this information enters the problem. Our realistic treatment takes into account entropy and composition gradients that exist in the nuclear matter, giving rise to buoyant g-mode oscillations. To illustrate the implementation, we determine the oscillation spectrum of a low-temperature neutron star. In addition to the expected compositional and thermal g-modes, we find perturbations sourced by phase transitions in the equation of state. We also examine the thermal evolution of the oscillation spectrum of a neutron star with constant redshifted temperature. |
1910.06791 | Joan Josep Ferrando | Joan Josep Ferrando and Juan Antonio S\'aez | Relativistic kinematic approach to the classical ideal gas | 22 pages, no figures | Class. Quantum Grav. 36 (2019) 215008 | 10.1088/1361-6382/ab4229 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | he necessary and sufficient conditions for a unit time-like vector field to
be the unit velocity of a classical ideal gas are obtained. In a recent paper
[Coll, Ferrando and S\'aez, Phys. Rev D {\bf 99} (2019)] we have offered a
purely hydrodynamic description of a classical ideal gas. Here we take one more
step in reducing the number of variables necessary to characterize these media
by showing that a plainly kinematic description can be obtained. We apply the
results to obtain test solutions to the hydrodynamic equation that model the
evolution in local thermal equilibrium of a classical ideal gas. \end{abstract}
| [
{
"created": "Tue, 15 Oct 2019 14:17:00 GMT",
"version": "v1"
}
] | 2019-10-16 | [
[
"Ferrando",
"Joan Josep",
""
],
[
"Sáez",
"Juan Antonio",
""
]
] | he necessary and sufficient conditions for a unit time-like vector field to be the unit velocity of a classical ideal gas are obtained. In a recent paper [Coll, Ferrando and S\'aez, Phys. Rev D {\bf 99} (2019)] we have offered a purely hydrodynamic description of a classical ideal gas. Here we take one more step in reducing the number of variables necessary to characterize these media by showing that a plainly kinematic description can be obtained. We apply the results to obtain test solutions to the hydrodynamic equation that model the evolution in local thermal equilibrium of a classical ideal gas. \end{abstract} |
2405.11101 | Tyler Grover | Owen Fiedorowicz, Tyler C. Grover, Vincent G. J. Rodgers, Hazal D.
Zenger | Diffeomorphism Radiative Degrees of Freedom of Thomas-Whitehead Gravity | 16 pages, 18 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The geometric action of the semi-direct product of the Kac-Moody and Virasoro
algebras contains the WZW action equipped with a background vector potential
$A$ associated to a coadjoint element of the Kac-Moody algebra as well as the
2D gravitational Polyakov action and an accompanying background field,
$\mathcal{D}$, called the diffeomorphism field. Just as the coadjoint element,
$A$, is related to a gauge fixed Yang-Mills vector potential $A_a$, the
diffeomorphism field, $\mathcal{D}$, is related to a component, $\mathcal{D}_{a
b}$ of the projectively invariant connection called the Thomas Operator. The
Yang-Mills action provides dynamics for the vector potential $A_a,$ while the
Thomas-Whitehead (TW) gravitational action, provides dynamics to
$\mathcal{D}_{ab}$. The TW action embeds the projectively invariant connection
into a gravitational theory that contains general relativity. In this work, the
diffeomorphism field $\mathcal{D}_{a b}$ is examined in Minkowski space where
salient features of this field can be explored. In particular, we study the
radiative degrees of freedom of this field while in a Minkowski space
background. We show that it can be decomposed into irreducible representations,
corresponding to tensor, vector, and scalar radiating solutions. Furthermore we
examine geodesic deviation in the context of TW gravity about a Minkowski space
background. We do this both at zeroth and first order in metric fluctuations
$h_{ab}$. We discuss that response of a gravitational wave antennae to the
geodesics deviations.
| [
{
"created": "Fri, 17 May 2024 21:38:51 GMT",
"version": "v1"
},
{
"created": "Sat, 20 Jul 2024 18:29:05 GMT",
"version": "v2"
}
] | 2024-07-23 | [
[
"Fiedorowicz",
"Owen",
""
],
[
"Grover",
"Tyler C.",
""
],
[
"Rodgers",
"Vincent G. J.",
""
],
[
"Zenger",
"Hazal D.",
""
]
] | The geometric action of the semi-direct product of the Kac-Moody and Virasoro algebras contains the WZW action equipped with a background vector potential $A$ associated to a coadjoint element of the Kac-Moody algebra as well as the 2D gravitational Polyakov action and an accompanying background field, $\mathcal{D}$, called the diffeomorphism field. Just as the coadjoint element, $A$, is related to a gauge fixed Yang-Mills vector potential $A_a$, the diffeomorphism field, $\mathcal{D}$, is related to a component, $\mathcal{D}_{a b}$ of the projectively invariant connection called the Thomas Operator. The Yang-Mills action provides dynamics for the vector potential $A_a,$ while the Thomas-Whitehead (TW) gravitational action, provides dynamics to $\mathcal{D}_{ab}$. The TW action embeds the projectively invariant connection into a gravitational theory that contains general relativity. In this work, the diffeomorphism field $\mathcal{D}_{a b}$ is examined in Minkowski space where salient features of this field can be explored. In particular, we study the radiative degrees of freedom of this field while in a Minkowski space background. We show that it can be decomposed into irreducible representations, corresponding to tensor, vector, and scalar radiating solutions. Furthermore we examine geodesic deviation in the context of TW gravity about a Minkowski space background. We do this both at zeroth and first order in metric fluctuations $h_{ab}$. We discuss that response of a gravitational wave antennae to the geodesics deviations. |
2407.14196 | Michele Lenzi | Jos\'e Luis Jaramillo, Michele Lenzi, Carlos F. Sopuerta | Integrability in Perturbed Black Holes: Background Hidden Structures | 23 pages, comments are welcome | null | null | null | gr-qc hep-th nlin.SI | http://creativecommons.org/licenses/by/4.0/ | In this work we investigate the presence of integrable hidden structures in
the dynamics of perturbed non-rotating black holes (BHs). This can also be
considered as a first step in a wider program of an effective identification of
``slow'' and ``fast'' degrees of freedom (DoFs) in the (binary) BH dynamics,
following a wave-mean flow perspective. The slow DoFs would be associated with
a nonlinear integrable dynamics, on which the fast ones propagate following an
effective linear dynamics. BH perturbation theory offers a natural ground to
test these properties. Indeed, the decoupling of Einstein equations into wave
master equations with a potential provides an instance of such splitting into
(frozen) slow DoFs (background potential) over which the linear dynamics of the
fast ones (perturbation master functions) evolve. It has been recently shown
that these wave equations possess an infinite number of symmetries that
correspond to the flow of the infinite hierarchy of Korteweg-de Vries (KdV)
equations. Starting from these results, we systematically investigate the
presence of integrable structures in BH perturbation theory. We first study
them in Cauchy slices and then extend the analysis to hyperboloidal foliations.
This second step introduces a splitting of the master equation into bulk and
boundary contributions, unveiling an underlying structural relation with the
slow and fast DoFs. This insight represents a first step to establish the
integrable structures associated to the slow DoFs as bulk symmetries of the
dynamics of perturbed BHs.
| [
{
"created": "Fri, 19 Jul 2024 10:48:22 GMT",
"version": "v1"
}
] | 2024-07-22 | [
[
"Jaramillo",
"José Luis",
""
],
[
"Lenzi",
"Michele",
""
],
[
"Sopuerta",
"Carlos F.",
""
]
] | In this work we investigate the presence of integrable hidden structures in the dynamics of perturbed non-rotating black holes (BHs). This can also be considered as a first step in a wider program of an effective identification of ``slow'' and ``fast'' degrees of freedom (DoFs) in the (binary) BH dynamics, following a wave-mean flow perspective. The slow DoFs would be associated with a nonlinear integrable dynamics, on which the fast ones propagate following an effective linear dynamics. BH perturbation theory offers a natural ground to test these properties. Indeed, the decoupling of Einstein equations into wave master equations with a potential provides an instance of such splitting into (frozen) slow DoFs (background potential) over which the linear dynamics of the fast ones (perturbation master functions) evolve. It has been recently shown that these wave equations possess an infinite number of symmetries that correspond to the flow of the infinite hierarchy of Korteweg-de Vries (KdV) equations. Starting from these results, we systematically investigate the presence of integrable structures in BH perturbation theory. We first study them in Cauchy slices and then extend the analysis to hyperboloidal foliations. This second step introduces a splitting of the master equation into bulk and boundary contributions, unveiling an underlying structural relation with the slow and fast DoFs. This insight represents a first step to establish the integrable structures associated to the slow DoFs as bulk symmetries of the dynamics of perturbed BHs. |
2305.02709 | Sachin Hatkar | S.P.Hatkar, S.P.Saraogi, S.D.Katore | Gravitational Wave from Domain Walls in $f(G)$ Theory | paper is communicated to journal | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we have studied Bianchi type I space-time in the presence of
domain walls in the context of $f(G)$ theory of gravitation. Field equations
are solved by using the special form of deceleration parameter. It is also
assumed that expansion is proportional to the shear scalar of the model. Some
physical parameters are discussed in detail.
| [
{
"created": "Thu, 4 May 2023 10:32:02 GMT",
"version": "v1"
}
] | 2023-05-05 | [
[
"Hatkar",
"S. P.",
""
],
[
"Saraogi",
"S. P.",
""
],
[
"Katore",
"S. D.",
""
]
] | In this paper, we have studied Bianchi type I space-time in the presence of domain walls in the context of $f(G)$ theory of gravitation. Field equations are solved by using the special form of deceleration parameter. It is also assumed that expansion is proportional to the shear scalar of the model. Some physical parameters are discussed in detail. |
gr-qc/9212013 | Malcolm MacCallum | M.A.H. MacCallum | Inhomogeneous and anisotropic cosmologies | 30pp | NATO Adv.Study Inst.Ser.C.Math.Phys.Sci.393:131-159,1993 | null | null | gr-qc | null | This is a review of cosmological models prepared for the Pont d'Oye workshop
on the origin of structure in the universe. The classes of models are discussed
in turn, and then some of their uses are considered.
| [
{
"created": "Mon, 21 Dec 1992 15:49:52 GMT",
"version": "v1"
}
] | 2011-03-28 | [
[
"MacCallum",
"M. A. H.",
""
]
] | This is a review of cosmological models prepared for the Pont d'Oye workshop on the origin of structure in the universe. The classes of models are discussed in turn, and then some of their uses are considered. |
2111.09068 | Leonardo Fernandez-Jambrina | L. Fern\'andez-Jambrina and R. Lazkoz | New futures for cosmological models | 2 tables, 11 pages, accepted for publication in Philosophical
Transactions of the Royal Society A | Phil. Trans. R. Soc. A 380: 20210333 (2022) | 10.1098/rsta.2021.0333 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The discovery of accelerated expansion of the universe opened the possibility
of new scenarios for the doom of our spacetime, besides aeternal expansion and
a final contraction. In this paper we review the chances which may await our
universe. In particular, there are new possible singular fates (sudden
singularities, big rip...), but there also other evolutions which cannot be
considered as singular. In addition to this, some of the singular fates are not
strong enough in the sense that the spacetime can be extended beyond the
singularity. For deriving our results we make use of generalised power and
asymptotic expansions of the scale factor of the universe.
| [
{
"created": "Wed, 17 Nov 2021 12:26:01 GMT",
"version": "v1"
}
] | 2022-03-01 | [
[
"Fernández-Jambrina",
"L.",
""
],
[
"Lazkoz",
"R.",
""
]
] | The discovery of accelerated expansion of the universe opened the possibility of new scenarios for the doom of our spacetime, besides aeternal expansion and a final contraction. In this paper we review the chances which may await our universe. In particular, there are new possible singular fates (sudden singularities, big rip...), but there also other evolutions which cannot be considered as singular. In addition to this, some of the singular fates are not strong enough in the sense that the spacetime can be extended beyond the singularity. For deriving our results we make use of generalised power and asymptotic expansions of the scale factor of the universe. |
2101.06372 | Hamidreza Saiedi | Hamidreza Saiedi | Thermodynamic Behavior of Time-Dependent Wormholes in Palatini $f(R)$
Gravity | null | Gen Relativ Gravit 53, 4 (2021) | 10.1007/s10714-020-02773-0 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the frame work of Palatini approach to modified $f(R)$ theories of
gravity, we attempt to investigate the thermodynamic behavior of time-dependent
wormhole geometries. By considering an evolving wormhole spacetime, we find the
field equations in Palatini $f(R)$ gravity. The energy density and pressure are
redefined in order to satisfy the continuity equation. To discuss the
thermodynamic behavior, an expression for the variation of total entropy is
obtained. Then, we extend our discussions to apparent and event horizons of
evolving wormholes. We employ the radius of apparent and event horizons to
determine the validity of generalized second law (GSL) of thermodynamics which
states that the variation of total entropy is non-negative.
| [
{
"created": "Sat, 16 Jan 2021 04:52:27 GMT",
"version": "v1"
}
] | 2021-01-19 | [
[
"Saiedi",
"Hamidreza",
""
]
] | In the frame work of Palatini approach to modified $f(R)$ theories of gravity, we attempt to investigate the thermodynamic behavior of time-dependent wormhole geometries. By considering an evolving wormhole spacetime, we find the field equations in Palatini $f(R)$ gravity. The energy density and pressure are redefined in order to satisfy the continuity equation. To discuss the thermodynamic behavior, an expression for the variation of total entropy is obtained. Then, we extend our discussions to apparent and event horizons of evolving wormholes. We employ the radius of apparent and event horizons to determine the validity of generalized second law (GSL) of thermodynamics which states that the variation of total entropy is non-negative. |
1906.00603 | Aurelien Barrau | Aur\'elien Barrau, Killian Martineau, Jeremy Martinon, Flora Moulin | Quasinormal modes of black holes in a toy-model for cumulative quantum
gravity | null | null | 10.1016/j.physletb.2019.06.033 | null | gr-qc astro-ph.CO hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The idea that quantum gravity effects might leak outside the horizon of a
black hole has recently been intensively considered. In this study, we
calculate the quasinormal modes as a function of the location and amplitude of
a generic metric perturbation distorting to the Schwarzschild spacetime. We
conclude on the possible observability of quantum metric corrections by current
and future gravitational wave experiments.
| [
{
"created": "Mon, 3 Jun 2019 07:08:54 GMT",
"version": "v1"
},
{
"created": "Tue, 18 Jun 2019 09:30:06 GMT",
"version": "v2"
},
{
"created": "Mon, 15 Aug 2022 17:11:10 GMT",
"version": "v3"
}
] | 2022-08-16 | [
[
"Barrau",
"Aurélien",
""
],
[
"Martineau",
"Killian",
""
],
[
"Martinon",
"Jeremy",
""
],
[
"Moulin",
"Flora",
""
]
] | The idea that quantum gravity effects might leak outside the horizon of a black hole has recently been intensively considered. In this study, we calculate the quasinormal modes as a function of the location and amplitude of a generic metric perturbation distorting to the Schwarzschild spacetime. We conclude on the possible observability of quantum metric corrections by current and future gravitational wave experiments. |
2107.13550 | Gamal G.L. Nashed | G.G.L. Nashed and Shin'ichi Nojiri | Mimetic Euler-Heisenberg theory, charged solutions and multi-horizon
black holes | 19 pages, 9 figures, accepted for publication in Phys. Rev. D | Phys. Rev. D 104, 044043, (2021) | 10.1103/PhysRevD.104.044043 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We construct several new classes of black hole (BH) solutions in the context
of the mimetic Euler-Heisenberg theory. We separately derive three differently
charged BH solutions and their relevant mimetic forms. We show that the
asymptotic form of all BH solutions behaves like a flat spacetime. These BHs,
either with/without cosmological constant, have the non constant Ricci scalar,
due to the contribution of the Euler-Heisenberg parameter, which means that
they are not solution to standard or mimetic $f(R)$ gravitational theory
without the Euler-Heisenberg non-linear electrodynamics and at the same time
they are not equivalent to the solutions of the Einstein gravity with a
massless scalar field. Moreover, we display that the effect of the
Euler-Heisenberg theory makes the singularity of BH solutions stronger compared
with that of BH solutions in general relativity. Furthermore, we show that the
null and strong energy conditions of those BH solutions are violated, which is
a general trend of mimetic gravitational theory. The thermodynamics of the BH
solutions are satisfactory although there appears a negative Hawking
temperature under some conditions. Additionally, these BHs obey the first law
of thermodynamics. We also study the stability, using the geodesic deviation,
and derive the stability condition analytically and graphically. Finally, for
the first time and under some conditions, we derived multi-horizon BH solutions
in the context of the mimetic Euler-Heisenberg theory and study their related
physics.
| [
{
"created": "Wed, 28 Jul 2021 12:13:05 GMT",
"version": "v1"
}
] | 2021-08-18 | [
[
"Nashed",
"G. G. L.",
""
],
[
"Nojiri",
"Shin'ichi",
""
]
] | We construct several new classes of black hole (BH) solutions in the context of the mimetic Euler-Heisenberg theory. We separately derive three differently charged BH solutions and their relevant mimetic forms. We show that the asymptotic form of all BH solutions behaves like a flat spacetime. These BHs, either with/without cosmological constant, have the non constant Ricci scalar, due to the contribution of the Euler-Heisenberg parameter, which means that they are not solution to standard or mimetic $f(R)$ gravitational theory without the Euler-Heisenberg non-linear electrodynamics and at the same time they are not equivalent to the solutions of the Einstein gravity with a massless scalar field. Moreover, we display that the effect of the Euler-Heisenberg theory makes the singularity of BH solutions stronger compared with that of BH solutions in general relativity. Furthermore, we show that the null and strong energy conditions of those BH solutions are violated, which is a general trend of mimetic gravitational theory. The thermodynamics of the BH solutions are satisfactory although there appears a negative Hawking temperature under some conditions. Additionally, these BHs obey the first law of thermodynamics. We also study the stability, using the geodesic deviation, and derive the stability condition analytically and graphically. Finally, for the first time and under some conditions, we derived multi-horizon BH solutions in the context of the mimetic Euler-Heisenberg theory and study their related physics. |
gr-qc/9706001 | Stephen A. Ramsey | S. A. Ramsey and B. L. Hu | O(N) Quantum fields in curved spacetime | 31 pages, 2 figures, uses RevTeX 3.1, LaTeX 2e, AMSfonts 2.2,
graphics 0.6; To appear in Phys. Rev. D (7/15/97) | Phys.Rev. D56 (1997) 661-677 | 10.1103/PhysRevD.56.661 | UMDPP#97-083 | gr-qc hep-ph | null | For the O(N) field theory with lambda Phi^4 self-coupling, we construct the
two-particle-irreducible (2PI), closed-time-path (CTP) effective action in a
general curved spacetime. From this we derive a set of coupled equations for
the mean field and the variance. They are useful for studying the
nonperturbative, nonequilibrium dynamics of a quantum field when full back
reactions of the quantum field on the curved spacetime, as well as the
fluctuations on the mean field, are required. Applications to phase transitions
in the early Universe such as the Planck scale or in the reheating phase of
chaotic inflation are under investigation.
| [
{
"created": "Mon, 2 Jun 1997 18:26:37 GMT",
"version": "v1"
}
] | 2009-10-30 | [
[
"Ramsey",
"S. A.",
""
],
[
"Hu",
"B. L.",
""
]
] | For the O(N) field theory with lambda Phi^4 self-coupling, we construct the two-particle-irreducible (2PI), closed-time-path (CTP) effective action in a general curved spacetime. From this we derive a set of coupled equations for the mean field and the variance. They are useful for studying the nonperturbative, nonequilibrium dynamics of a quantum field when full back reactions of the quantum field on the curved spacetime, as well as the fluctuations on the mean field, are required. Applications to phase transitions in the early Universe such as the Planck scale or in the reheating phase of chaotic inflation are under investigation. |
gr-qc/9607061 | Alicia Sintes | J. Carot and A.M. Sintes | Homothetic perfect fluid space-times | 27 pages, Latex file, Submitted to Class. Quantum Grav | Class.Quant.Grav. 14 (1997) 1183-1205 | 10.1088/0264-9381/14/5/021 | null | gr-qc | null | A brief summary of results on homotheties in General Relativity is given,
including general information about space-times admitting an r-parameter group
of homothetic transformations for r>2, as well as some specific results on
perfect fluids. Attention is then focussed on inhomogeneous models, in
particular on those with a homothetic group $H_4$ (acting multiply
transitively) and $H_3$. A classification of all possible Lie algebra
structures along with (local) coordinate expressions for the metric and
homothetic vectors is then provided (irrespectively of the matter content), and
some new perfect fluid solutions are given and briefly discussed.
| [
{
"created": "Wed, 24 Jul 1996 14:12:01 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Carot",
"J.",
""
],
[
"Sintes",
"A. M.",
""
]
] | A brief summary of results on homotheties in General Relativity is given, including general information about space-times admitting an r-parameter group of homothetic transformations for r>2, as well as some specific results on perfect fluids. Attention is then focussed on inhomogeneous models, in particular on those with a homothetic group $H_4$ (acting multiply transitively) and $H_3$. A classification of all possible Lie algebra structures along with (local) coordinate expressions for the metric and homothetic vectors is then provided (irrespectively of the matter content), and some new perfect fluid solutions are given and briefly discussed. |
1111.6908 | Niels Warburton | Niels Warburton, Sarp Akcay, Leor Barack, Jonathan R. Gair, Norichika
Sago | Evolution of inspiral orbits around a Schwarzschild black hole | 4 pages, 3 figures, Fast GSF calculator code available at:
http://www.nielswarburton.net/lib_Sch_GSF/ | Phys. Rev. D 85, 061501(R) (2012) | 10.1103/PhysRevD.85.061501 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present results from calculations of the orbital evolution in eccentric
binaries of nonrotating black holes with extreme mass-ratios. Our inspiral
model is based on the method of osculating geodesics, and is the first to
incorporate the full gravitational self-force (GSF) effect, including
conservative corrections. The GSF information is encapsulated in an analytic
interpolation formula based on numerical GSF data for over a thousand sample
geodesic orbits. We assess the importance of including conservative GSF
corrections in waveform models for gravitational-wave searches.
| [
{
"created": "Tue, 29 Nov 2011 17:19:11 GMT",
"version": "v1"
},
{
"created": "Mon, 5 Mar 2012 21:06:43 GMT",
"version": "v2"
},
{
"created": "Tue, 10 Dec 2013 12:36:51 GMT",
"version": "v3"
}
] | 2013-12-11 | [
[
"Warburton",
"Niels",
""
],
[
"Akcay",
"Sarp",
""
],
[
"Barack",
"Leor",
""
],
[
"Gair",
"Jonathan R.",
""
],
[
"Sago",
"Norichika",
""
]
] | We present results from calculations of the orbital evolution in eccentric binaries of nonrotating black holes with extreme mass-ratios. Our inspiral model is based on the method of osculating geodesics, and is the first to incorporate the full gravitational self-force (GSF) effect, including conservative corrections. The GSF information is encapsulated in an analytic interpolation formula based on numerical GSF data for over a thousand sample geodesic orbits. We assess the importance of including conservative GSF corrections in waveform models for gravitational-wave searches. |
2207.14217 | Arick Shao | Gustav Holzegel, Arick Shao | The bulk-boundary correspondence for the Einstein equations in
asymptotically Anti-de Sitter spacetimes | 60 pages, 1 figure. Version accepted at ARMA | null | 10.1007/s00205-023-01890-9 | null | gr-qc hep-th math.AP | http://creativecommons.org/licenses/by/4.0/ | In this paper, we consider vacuum asymptotically anti-de Sitter spacetimes $(
\mathscr{M}, g )$ with conformal boundary $( \mathscr{I}, \mathfrak{g} )$. We
establish a correspondence, near $\mathscr{I}$, between such spacetimes and
their conformal boundary data on $\mathscr{I}$. More specifically, given a
domain $\mathscr{D} \subset \mathscr{I}$, we prove that the coefficients
$\mathfrak{g}^{(0)} = \mathfrak{g}$ and $\mathfrak{g}^{(n)}$ (the undetermined
term or stress energy tensor) in a Fefferman-Graham expansion of the metric $g$
from the boundary uniquely determine $g$ near $\mathscr{D}$, provided
$\mathscr{D}$ satisfies a generalised null convexity condition (GNCC). The GNCC
is a conformally invariant criterion on $\mathscr{D}$, first identified by
Chatzikaleas and the second author, that ensures a foliation of pseudoconvex
hypersurfaces in $\mathscr{M}$ near $\mathscr{D}$, and with the pseudoconvexity
degenerating in the limit at $\mathscr{D}$. As a corollary of this result, we
deduce that conformal symmetries of $( \mathfrak{g}^{(0)}, \mathfrak{g}^{(n)}
)$ on domains $\mathscr{D} \subset \mathscr{I}$ satisfying the GNCC extend to
spacetimes symmetries near $\mathscr{D}$. The proof, which does not require any
analyticity assumptions, relies on three key ingredients: (1) a calculus of
vertical tensor-fields developed for this setting; (2) a novel system of
transport and wave equations for differences of metric and curvature
quantities; and (3) recently established Carleman estimates for tensorial wave
equations near the conformal boundary.
| [
{
"created": "Thu, 28 Jul 2022 16:34:59 GMT",
"version": "v1"
},
{
"created": "Sat, 22 Apr 2023 14:34:18 GMT",
"version": "v2"
}
] | 2023-06-14 | [
[
"Holzegel",
"Gustav",
""
],
[
"Shao",
"Arick",
""
]
] | In this paper, we consider vacuum asymptotically anti-de Sitter spacetimes $( \mathscr{M}, g )$ with conformal boundary $( \mathscr{I}, \mathfrak{g} )$. We establish a correspondence, near $\mathscr{I}$, between such spacetimes and their conformal boundary data on $\mathscr{I}$. More specifically, given a domain $\mathscr{D} \subset \mathscr{I}$, we prove that the coefficients $\mathfrak{g}^{(0)} = \mathfrak{g}$ and $\mathfrak{g}^{(n)}$ (the undetermined term or stress energy tensor) in a Fefferman-Graham expansion of the metric $g$ from the boundary uniquely determine $g$ near $\mathscr{D}$, provided $\mathscr{D}$ satisfies a generalised null convexity condition (GNCC). The GNCC is a conformally invariant criterion on $\mathscr{D}$, first identified by Chatzikaleas and the second author, that ensures a foliation of pseudoconvex hypersurfaces in $\mathscr{M}$ near $\mathscr{D}$, and with the pseudoconvexity degenerating in the limit at $\mathscr{D}$. As a corollary of this result, we deduce that conformal symmetries of $( \mathfrak{g}^{(0)}, \mathfrak{g}^{(n)} )$ on domains $\mathscr{D} \subset \mathscr{I}$ satisfying the GNCC extend to spacetimes symmetries near $\mathscr{D}$. The proof, which does not require any analyticity assumptions, relies on three key ingredients: (1) a calculus of vertical tensor-fields developed for this setting; (2) a novel system of transport and wave equations for differences of metric and curvature quantities; and (3) recently established Carleman estimates for tensorial wave equations near the conformal boundary. |
2407.00366 | Niels Warburton | Niels Warburton, Barry Wardell, David Trestini, Quentin Henry, Adam
Pound, Luc Blanchet, Leanne Durkan, Guillaume Faye, Jeremy Miller | Comparison of 4.5PN and 2SF gravitational energy fluxes from
quasicircular compact binaries | 15 pages, 4 figures, modes of PN flux provided in ancillary file | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The past three years have seen two significant advances in models of
gravitational waveforms emitted by quasicircular compact binaries in two
regimes: the weak-field, post-Newtonian regime, in which the gravitational wave
energy flux has now been calculated to fourth-and-a-half post-Newtonian order
(4.5PN) [Phys. Rev. Lett. 131, 121402 (2023)]; and the small-mass-ratio,
gravitational self-force regime, in which the flux has now been calculated to
second perturbative order in the mass ratio (2SF) [Phys. Rev. Lett. 127, 151102
(2021)]. We compare these results and find excellent agreement for the total
flux, showing consistency between the two calculations at all available PN and
SF orders. However, although the total fluxes agree, we find disagreements in
the fluxes due to individual spherical-harmonic modes of the waveform, strongly
suggesting the two waveforms might be in different asymptotic frames.
| [
{
"created": "Sat, 29 Jun 2024 08:31:38 GMT",
"version": "v1"
}
] | 2024-07-02 | [
[
"Warburton",
"Niels",
""
],
[
"Wardell",
"Barry",
""
],
[
"Trestini",
"David",
""
],
[
"Henry",
"Quentin",
""
],
[
"Pound",
"Adam",
""
],
[
"Blanchet",
"Luc",
""
],
[
"Durkan",
"Leanne",
""
],
[
"Fa... | The past three years have seen two significant advances in models of gravitational waveforms emitted by quasicircular compact binaries in two regimes: the weak-field, post-Newtonian regime, in which the gravitational wave energy flux has now been calculated to fourth-and-a-half post-Newtonian order (4.5PN) [Phys. Rev. Lett. 131, 121402 (2023)]; and the small-mass-ratio, gravitational self-force regime, in which the flux has now been calculated to second perturbative order in the mass ratio (2SF) [Phys. Rev. Lett. 127, 151102 (2021)]. We compare these results and find excellent agreement for the total flux, showing consistency between the two calculations at all available PN and SF orders. However, although the total fluxes agree, we find disagreements in the fluxes due to individual spherical-harmonic modes of the waveform, strongly suggesting the two waveforms might be in different asymptotic frames. |
2301.13610 | Pardyumn Kumar Sahoo | Z. Yousaf, M. Z. Bhatti, H. Aman, P.K. Sahoo | Non-Singular Bouncing Model in Energy Momentum Squared Gravity | Physica Scripta accepted version | Physica Scripta, 98 (2023) 035002 | 10.1088/1402-4896/acb6c3 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | This work is concerned to study the bouncing nature of the universe for an
isotropic configuration of fluid $\mathcal{T}_{\alpha\beta}$ and
Friedmann-Lema\^{i}tre-Robertson-Walker metric scheme. This work is carried out
under the novel $f(\mathcal{G},\mathcal{T}_{\alpha \beta} \mathcal{T}^{\alpha
\beta})$ gravitation by assuming a specific model i.e,
$f(\mathcal{G},\mathcal{T}^2)=\mathcal{G}+\alpha \mathcal{G}^2+2\lambda
\mathcal{T}^2$ with $\alpha$ and $\lambda$ are constants, serving as free
parameters. {The terms $\mathcal{G}$ and $\mathcal{T}^2$ served as an
Gauss-Bonnet invariant and square of the energy-momentum trace term as an
inclusion in the gravitational action respectively, and is proportional to
$\mathcal{T}^2=\mathcal{T}_{\alpha \beta} \mathcal{T}^{\alpha \beta}$.} A
specific functional form of the Hubble parameter is taken to provide the
evolution of cosmographic parameters. A well known equation of state parameter,
$\omega(t)=-\frac{k \log (t+\epsilon )}{t}-1$ is used to represent the
dynamical behavior of energy density, matter pressure and energy conditions. A
detailed graphical analysis is also provided to review the bounce. Furthermore,
all free parameters are set in a way, to make the supposed Hubble parameter act
as the bouncing solution and ensure the viability of energy conditions.
Conclusively, all necessary conditions for a bouncing model are checked.
| [
{
"created": "Mon, 30 Jan 2023 15:57:22 GMT",
"version": "v1"
}
] | 2023-02-08 | [
[
"Yousaf",
"Z.",
""
],
[
"Bhatti",
"M. Z.",
""
],
[
"Aman",
"H.",
""
],
[
"Sahoo",
"P. K.",
""
]
] | This work is concerned to study the bouncing nature of the universe for an isotropic configuration of fluid $\mathcal{T}_{\alpha\beta}$ and Friedmann-Lema\^{i}tre-Robertson-Walker metric scheme. This work is carried out under the novel $f(\mathcal{G},\mathcal{T}_{\alpha \beta} \mathcal{T}^{\alpha \beta})$ gravitation by assuming a specific model i.e, $f(\mathcal{G},\mathcal{T}^2)=\mathcal{G}+\alpha \mathcal{G}^2+2\lambda \mathcal{T}^2$ with $\alpha$ and $\lambda$ are constants, serving as free parameters. {The terms $\mathcal{G}$ and $\mathcal{T}^2$ served as an Gauss-Bonnet invariant and square of the energy-momentum trace term as an inclusion in the gravitational action respectively, and is proportional to $\mathcal{T}^2=\mathcal{T}_{\alpha \beta} \mathcal{T}^{\alpha \beta}$.} A specific functional form of the Hubble parameter is taken to provide the evolution of cosmographic parameters. A well known equation of state parameter, $\omega(t)=-\frac{k \log (t+\epsilon )}{t}-1$ is used to represent the dynamical behavior of energy density, matter pressure and energy conditions. A detailed graphical analysis is also provided to review the bounce. Furthermore, all free parameters are set in a way, to make the supposed Hubble parameter act as the bouncing solution and ensure the viability of energy conditions. Conclusively, all necessary conditions for a bouncing model are checked. |
1412.1527 | Ran Li | Ran Li, Junkun Zhao | Numerical study of superradiant instability for charged stringy black
hole-mirror system | 5 pages, 5 figures, accepted by PLB. arXiv admin note: text overlap
with arXiv:1403.7279 | Phys. Lett. B 740(2015)317-321 | 10.1016/j.physletb.2014.12.007 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We numerically study the superradiant instability of charged massless scalar
field in the background of charged stringy black hole with mirror-like boundary
condition. We compare the numerical result with the previous analytical result
and show the dependencies of this instability upon various parameters of black
hole charge $Q$, scalar field charge $q$, and mirror radius $r_m$. Especially,
we have observed that imaginary part of BQN frequencies grows with the scalar
field charge $q$ rapidly.
| [
{
"created": "Thu, 4 Dec 2014 00:55:44 GMT",
"version": "v1"
}
] | 2015-01-14 | [
[
"Li",
"Ran",
""
],
[
"Zhao",
"Junkun",
""
]
] | We numerically study the superradiant instability of charged massless scalar field in the background of charged stringy black hole with mirror-like boundary condition. We compare the numerical result with the previous analytical result and show the dependencies of this instability upon various parameters of black hole charge $Q$, scalar field charge $q$, and mirror radius $r_m$. Especially, we have observed that imaginary part of BQN frequencies grows with the scalar field charge $q$ rapidly. |
1109.3655 | S Habib Mazharimousavi | S. Habib Mazharimousavi, M. Halilsoy and T. Tahamtan | Constant curvature f(R) gravity minimally coupled with Yang-Mills field | 12 pages 2 figures, Some references and 2 figures are added with
minor changes. Final version for publication in European Physical Journal C | Eur. Phys. J. C (2012) 72:1958 | 10.1140/epjc/s10052-012-1958-5 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the particular class of f(R) gravities minimally coupled with
Yang - Mills (YM) field in which the Ricci scalar =R_{0}= constant in all
dimensions d\geq4. Even in this restricted class the spacetime has unlimited
scopes determined by an equation of state of the form P_{eff}={\omega}{\rho}.
Depending on the distance from the origin (or horizon of a black hole) the
state function {\omega}(r) takes different values. It is observed that
{\omega}\rightarrow(1/3) (the ultra relativistic case in 4 - dimensions) and
{\omega}\rightarrow-1 (the cosmological constant) are the limiting values of
our state function {\omega}(r) in a spacetime centered by a black hole. This
suggests that having a constant {\omega} throughout spacetime around a charged
black hole in f(R) gravity with constant scalar curvature is a myth.
| [
{
"created": "Fri, 16 Sep 2011 16:10:03 GMT",
"version": "v1"
},
{
"created": "Wed, 1 Feb 2012 15:42:51 GMT",
"version": "v2"
},
{
"created": "Sat, 3 Mar 2012 19:43:55 GMT",
"version": "v3"
},
{
"created": "Mon, 12 Mar 2012 20:44:41 GMT",
"version": "v4"
}
] | 2012-04-02 | [
[
"Mazharimousavi",
"S. Habib",
""
],
[
"Halilsoy",
"M.",
""
],
[
"Tahamtan",
"T.",
""
]
] | We consider the particular class of f(R) gravities minimally coupled with Yang - Mills (YM) field in which the Ricci scalar =R_{0}= constant in all dimensions d\geq4. Even in this restricted class the spacetime has unlimited scopes determined by an equation of state of the form P_{eff}={\omega}{\rho}. Depending on the distance from the origin (or horizon of a black hole) the state function {\omega}(r) takes different values. It is observed that {\omega}\rightarrow(1/3) (the ultra relativistic case in 4 - dimensions) and {\omega}\rightarrow-1 (the cosmological constant) are the limiting values of our state function {\omega}(r) in a spacetime centered by a black hole. This suggests that having a constant {\omega} throughout spacetime around a charged black hole in f(R) gravity with constant scalar curvature is a myth. |
gr-qc/9312021 | Bill Pezzaglia | William M. Pezzaglia Jr | Multivector Solutions to the Hyper-Holomorphic Massive Dirac Equation | 13 pages (Latex), Report# clf-alg/pezz9302 | null | null | null | gr-qc hep-th | null | Attention is given to the interface of mathematics and physics, specifically
noting that fundamental principles limit the usefulness of otherwise perfectly
good mathematical general integral solutions. A new set of multivector
solutions to the meta-monogenic (massive) Dirac equation is constructed which
form a Hilbert space. A new integral solution is proposed which involves
application of a kernel to the right side of the function, instead of to the
left as usual. This allows for the introduction of a multivector generalization
of the Feynman Path Integral formulation, which shows that particular
``geometric groupings'' of solutions evolve in the manner to which we ascribe
the term ``quantum particle''. Further, it is shown that the role of usual $i$
is subplanted by the unit time basis vector, applied on the right side of the
functions. Summary of talk, to appear in: Proceedings of the 17th Annual
Lecture Series in the Mathematical Sciences, April 8-10, 1993, University of
Arkansas, `Clifford Algebas in Analysis', J. Ryan, editor (CRC Press, expected
1994)
| [
{
"created": "Wed, 15 Dec 1993 13:35:27 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Pezzaglia",
"William M.",
"Jr"
]
] | Attention is given to the interface of mathematics and physics, specifically noting that fundamental principles limit the usefulness of otherwise perfectly good mathematical general integral solutions. A new set of multivector solutions to the meta-monogenic (massive) Dirac equation is constructed which form a Hilbert space. A new integral solution is proposed which involves application of a kernel to the right side of the function, instead of to the left as usual. This allows for the introduction of a multivector generalization of the Feynman Path Integral formulation, which shows that particular ``geometric groupings'' of solutions evolve in the manner to which we ascribe the term ``quantum particle''. Further, it is shown that the role of usual $i$ is subplanted by the unit time basis vector, applied on the right side of the functions. Summary of talk, to appear in: Proceedings of the 17th Annual Lecture Series in the Mathematical Sciences, April 8-10, 1993, University of Arkansas, `Clifford Algebas in Analysis', J. Ryan, editor (CRC Press, expected 1994) |
2101.01028 | Jan Smit | Jan Smit | Three models of non-perturbative quantum-gravitational binding | Improved presentation with additional references and special
attention to the dynamical triangulation (DT) part; extended and refined
analysis of the early DT results; 53 pages of which 20 in appendices and
references | null | null | null | gr-qc hep-lat hep-th | http://creativecommons.org/licenses/by/4.0/ | Known quantum and classical perturbative long-distance corrections to the
Newton potential are extended into the short-distance regime using evolution
equations for a `running' gravitational coupling, which is used to construct
examples non-perturbative potentials for the gravitational binding of two
particles. Model-I is based on the complete set of the relevant Feynman
diagrams. Its potential has a singularity at a distance below which it becomes
complex and the system gets black hole-like features. Model-II is based on a
reduced set of diagrams and its coupling approaches a non-Gaussian fixed point
as the distance is reduced. Energies and eigenfunctions are obtained and used
in a study of time-dependent collapse (model-I) and bouncing (both models) of a
spherical wave packet. The motivation for such non-perturbative `toy' models
stems from a desire to elucidate the mass dependence of binding energies found
25 years ago in an explorative numerical simulation within the dynamical
triangulation approach to quantum gravity. Models I \& II suggest indeed an
explanation of this mass dependence, in which the Schwarzschild scale plays a
role. An estimate of the renormalized Newton coupling is made by matching with
the small-mass region. Comparison of the dynamical triangulation results for
mass renormalization with `renormalized perturbation theory' in the continuum
leads to an independent estimate of this coupling, which is used in an improved
analysis of the binding energy data.
| [
{
"created": "Mon, 4 Jan 2021 15:26:37 GMT",
"version": "v1"
},
{
"created": "Sun, 17 Jan 2021 20:13:46 GMT",
"version": "v2"
},
{
"created": "Sun, 22 Aug 2021 13:57:38 GMT",
"version": "v3"
}
] | 2021-08-24 | [
[
"Smit",
"Jan",
""
]
] | Known quantum and classical perturbative long-distance corrections to the Newton potential are extended into the short-distance regime using evolution equations for a `running' gravitational coupling, which is used to construct examples non-perturbative potentials for the gravitational binding of two particles. Model-I is based on the complete set of the relevant Feynman diagrams. Its potential has a singularity at a distance below which it becomes complex and the system gets black hole-like features. Model-II is based on a reduced set of diagrams and its coupling approaches a non-Gaussian fixed point as the distance is reduced. Energies and eigenfunctions are obtained and used in a study of time-dependent collapse (model-I) and bouncing (both models) of a spherical wave packet. The motivation for such non-perturbative `toy' models stems from a desire to elucidate the mass dependence of binding energies found 25 years ago in an explorative numerical simulation within the dynamical triangulation approach to quantum gravity. Models I \& II suggest indeed an explanation of this mass dependence, in which the Schwarzschild scale plays a role. An estimate of the renormalized Newton coupling is made by matching with the small-mass region. Comparison of the dynamical triangulation results for mass renormalization with `renormalized perturbation theory' in the continuum leads to an independent estimate of this coupling, which is used in an improved analysis of the binding energy data. |
gr-qc/9304019 | Piotr T. Chrusciel | Lars Andersson, Piotr T. Chrusciel | On ``hyperboloidal'' Cauchy data for vacuum Einstein equations and
obstructions to smoothness of ``null infinity'' | 8 pages, revtex style | Phys.Rev.Lett. 70 (1993) 2829-2832 | 10.1103/PhysRevLett.70.2829 | null | gr-qc | null | Various works have suggested that the Bondi--Sachs--Penrose decay conditions
on the gravitational field at null infinity are not generally representative of
asymptotically flat space--times. We have made a detailed analysis of the
constraint equations for ``asymptotically hyperboloidal'' initial data and find
that log terms arise generically in asymptotic expansions. These terms are
absent in the corresponding Bondi--Sachs--Penrose expansions, and can be
related to explicit geometric quantities. We have nevertheless shown that there
exists a large class of ``non--generic'' solutions of the constraint equations,
the evolution of which leads to space--times satisfying the
Bondi--Sachs--Penrose smoothness conditions.
| [
{
"created": "Thu, 15 Apr 1993 20:19:54 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Andersson",
"Lars",
""
],
[
"Chrusciel",
"Piotr T.",
""
]
] | Various works have suggested that the Bondi--Sachs--Penrose decay conditions on the gravitational field at null infinity are not generally representative of asymptotically flat space--times. We have made a detailed analysis of the constraint equations for ``asymptotically hyperboloidal'' initial data and find that log terms arise generically in asymptotic expansions. These terms are absent in the corresponding Bondi--Sachs--Penrose expansions, and can be related to explicit geometric quantities. We have nevertheless shown that there exists a large class of ``non--generic'' solutions of the constraint equations, the evolution of which leads to space--times satisfying the Bondi--Sachs--Penrose smoothness conditions. |
2001.04494 | Tommi Markkanen | Tommi Markkanen and Arttu Rajantie | Scalar correlation functions for a double-well potential in de Sitter
space | 21 pages, 12 figures. v2: fixed typos, updated references. v3:
improved figures, to be published in JCAP | null | 10.1088/1475-7516/2020/03/049 | IMPERIAL-TP-2020-AR-1 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We use the spectral representation of the stochastic Starobinsky-Yokoyama
approach to compute correlation functions in de Sitter space for a scalar field
with a symmetric or asymmetric double-well potential. The terms in the spectral
expansion are determined by the eigenvalues and eigenfunctions of the
time-independent Fokker-Planck differential operator, and we solve them
numerically. The long-distance asymptotic behaviour is given by the lowest
state in the spectrum, but we demonstrate that the magnitude of the coeffients
of different terms can be very different, and the correlator can be dominated
by different terms at different distances. This can give rise to potentially
observable cosmological signatures. In many cases the dominant states in the
expansion do not correspond to small fluctuations around a minimum of the
potential and are therefore not visible in perturbation theory. We discuss the
physical interpretation these states, which can be present even when the
potential has only one minimum.
| [
{
"created": "Mon, 13 Jan 2020 19:04:14 GMT",
"version": "v1"
},
{
"created": "Fri, 31 Jan 2020 11:01:32 GMT",
"version": "v2"
},
{
"created": "Wed, 19 Feb 2020 13:12:28 GMT",
"version": "v3"
}
] | 2020-03-26 | [
[
"Markkanen",
"Tommi",
""
],
[
"Rajantie",
"Arttu",
""
]
] | We use the spectral representation of the stochastic Starobinsky-Yokoyama approach to compute correlation functions in de Sitter space for a scalar field with a symmetric or asymmetric double-well potential. The terms in the spectral expansion are determined by the eigenvalues and eigenfunctions of the time-independent Fokker-Planck differential operator, and we solve them numerically. The long-distance asymptotic behaviour is given by the lowest state in the spectrum, but we demonstrate that the magnitude of the coeffients of different terms can be very different, and the correlator can be dominated by different terms at different distances. This can give rise to potentially observable cosmological signatures. In many cases the dominant states in the expansion do not correspond to small fluctuations around a minimum of the potential and are therefore not visible in perturbation theory. We discuss the physical interpretation these states, which can be present even when the potential has only one minimum. |
2109.11138 | Vladimir Folomeev | Vladimir Dzhunushaliev and Vladimir Folomeev | Axially symmetric Proca-Higgs boson stars | 9 pages, 2 figures, minor corrections to content, version published
in PRD | Phys. Rev. D 104, 104024 (2021) | 10.1103/PhysRevD.104.104024 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We consider strongly gravitating configurations consisting of coupled real
Higgs scalar field and vector (Proca) field of mass $\mu_P$. For such a system,
we find static regular axially symmetric solutions describing asymptotically
flat configurations which may be referred to as Proca-Higgs miniboson stars,
since their total mass and spatial dimension are of order
$M_{\text{Pl}}^2/\mu_P$ and $\mu_P^{-1}$, respectively.The system possesses an
axially symmetric dipole field and may be regarded as a Proca dipole.
| [
{
"created": "Thu, 23 Sep 2021 04:40:39 GMT",
"version": "v1"
},
{
"created": "Wed, 10 Nov 2021 08:05:57 GMT",
"version": "v2"
}
] | 2021-11-11 | [
[
"Dzhunushaliev",
"Vladimir",
""
],
[
"Folomeev",
"Vladimir",
""
]
] | We consider strongly gravitating configurations consisting of coupled real Higgs scalar field and vector (Proca) field of mass $\mu_P$. For such a system, we find static regular axially symmetric solutions describing asymptotically flat configurations which may be referred to as Proca-Higgs miniboson stars, since their total mass and spatial dimension are of order $M_{\text{Pl}}^2/\mu_P$ and $\mu_P^{-1}$, respectively.The system possesses an axially symmetric dipole field and may be regarded as a Proca dipole. |
1608.03808 | Yuri Obukhov | Yuri N. Obukhov, Alexander J. Silenko, and Oleg V. Teryaev | Manifestations of the rotation and gravity of the Earth in high-energy
physics experiments | 13 pages, Revtex | Phys. Rev. D 94, 044019 (2016) | 10.1103/PhysRevD.94.044019 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The inertial (due to rotation) and gravitational fields of the Earth affect
the motion of an elementary particle and its spin dynamics. This influence is
not negligible and should be taken into account in high-energy physics
experiments. Earth's influence is manifest in perturbations in the particle
motion, in an additional precession of the spin, and in a change of the
constitutive tensor of the Maxwell electrodynamics. Bigger corrections are
oscillatory, and their contributions average to zero. Other corrections due to
the inhomogeneity of the inertial field are not oscillatory but they are very
small and may be important only for the storage ring electric dipole moment
experiments. Earth's gravity causes the Newton-like force, the reaction force
provided by a focusing system, and additional torques acting on the spin.
However, there are no observable indications of the electromagnetic effects due
to Earth's gravity.
| [
{
"created": "Thu, 11 Aug 2016 08:47:20 GMT",
"version": "v1"
}
] | 2016-08-15 | [
[
"Obukhov",
"Yuri N.",
""
],
[
"Silenko",
"Alexander J.",
""
],
[
"Teryaev",
"Oleg V.",
""
]
] | The inertial (due to rotation) and gravitational fields of the Earth affect the motion of an elementary particle and its spin dynamics. This influence is not negligible and should be taken into account in high-energy physics experiments. Earth's influence is manifest in perturbations in the particle motion, in an additional precession of the spin, and in a change of the constitutive tensor of the Maxwell electrodynamics. Bigger corrections are oscillatory, and their contributions average to zero. Other corrections due to the inhomogeneity of the inertial field are not oscillatory but they are very small and may be important only for the storage ring electric dipole moment experiments. Earth's gravity causes the Newton-like force, the reaction force provided by a focusing system, and additional torques acting on the spin. However, there are no observable indications of the electromagnetic effects due to Earth's gravity. |
gr-qc/0506129 | Parampreet Singh | Rituparno Goswami, Pankaj S. Joshi, Parampreet Singh | Quantum evaporation of a naked singularity | 4 pages, 2 figures. Minor changes to match published version in
Physical Review Letters | Phys.Rev.Lett. 96 (2006) 031302 | 10.1103/PhysRevLett.96.031302 | IGPG-05/6-8 | gr-qc astro-ph hep-th | null | We investigate here quantum effects in gravitational collapse of a scalar
field model which classically leads to a naked singularity. We show that
non-perturbative semi-classical modifications near the singularity, based on
loop quantum gravity, give rise to a strong outward flux of energy. This leads
to the dissolution of the collapsing cloud before the singularity can form.
Quantum gravitational effects thus censor naked singularities by avoiding their
formation. Further, quantum gravity induced mass flux has a distinct feature
which may lead to a novel observable signature in astrophysical bursts.
| [
{
"created": "Tue, 28 Jun 2005 22:27:28 GMT",
"version": "v1"
},
{
"created": "Sun, 22 Jan 2006 18:05:48 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Goswami",
"Rituparno",
""
],
[
"Joshi",
"Pankaj S.",
""
],
[
"Singh",
"Parampreet",
""
]
] | We investigate here quantum effects in gravitational collapse of a scalar field model which classically leads to a naked singularity. We show that non-perturbative semi-classical modifications near the singularity, based on loop quantum gravity, give rise to a strong outward flux of energy. This leads to the dissolution of the collapsing cloud before the singularity can form. Quantum gravitational effects thus censor naked singularities by avoiding their formation. Further, quantum gravity induced mass flux has a distinct feature which may lead to a novel observable signature in astrophysical bursts. |
1004.3569 | David Garfinkle | Ryo Saotome, Ratindranath Akhoury and David Garfinkle | Examining gravitational collapse with test scalar fields | 10 pages, 11 figures, references added | Class.Quant.Grav.27:165019,2010 | 10.1088/0264-9381/27/16/165019 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Numerical simulations are performed of a test scalar field in a spacetime
undergoing gravitational collapse. The behavior of the scalar field near the
singularity is examined and implications for generic singularities are
discussed. In particular, our example is the first confirmation of the BKL
conjecture for an asymptotically flat spacetime.
| [
{
"created": "Tue, 20 Apr 2010 20:40:33 GMT",
"version": "v1"
},
{
"created": "Wed, 5 May 2010 12:32:20 GMT",
"version": "v2"
}
] | 2011-09-12 | [
[
"Saotome",
"Ryo",
""
],
[
"Akhoury",
"Ratindranath",
""
],
[
"Garfinkle",
"David",
""
]
] | Numerical simulations are performed of a test scalar field in a spacetime undergoing gravitational collapse. The behavior of the scalar field near the singularity is examined and implications for generic singularities are discussed. In particular, our example is the first confirmation of the BKL conjecture for an asymptotically flat spacetime. |
0901.2358 | Gary Poon | Gary Poon | Relative Unitary Implementability of Perturbed Quantum Field Dynamics on
de-Sitter Space | PhD Thesis, 33 Pages | J.Math.Phys.51:042503,2010 | 10.1063/1.3387251 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this article, we study the quantum dynamics of a Klein-Gordon field on
de-Sitter space. We prove time evolution is not unitarily implementable. We
also consider a Klein-Gordon field perturbed by a local potential V. In this
case we prove that the deviation from the V=0 dynamics is unitarily
implementable.
| [
{
"created": "Thu, 15 Jan 2009 22:09:50 GMT",
"version": "v1"
},
{
"created": "Tue, 9 Jun 2009 18:57:27 GMT",
"version": "v2"
}
] | 2014-11-18 | [
[
"Poon",
"Gary",
""
]
] | In this article, we study the quantum dynamics of a Klein-Gordon field on de-Sitter space. We prove time evolution is not unitarily implementable. We also consider a Klein-Gordon field perturbed by a local potential V. In this case we prove that the deviation from the V=0 dynamics is unitarily implementable. |
1502.06539 | David Wallace | David Wallace | Fields as Bodies: a unified presentation of spacetime and internal gauge
symmetry | null | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using the parametrised representation of field theory (in which the location
in spacetime of a part of a field is itself represented by a map from the base
manifold to Minkowski spacetime) I demonstrate that in both local and global
cases, internal (Yang-Mills-type) and spacetime (Poincar\'{e}) symmetries can
be treated precisely on a par, so that gravitational theories may be regarded
as gauge theories in a completely standard sense.
| [
{
"created": "Mon, 23 Feb 2015 18:27:40 GMT",
"version": "v1"
}
] | 2015-02-24 | [
[
"Wallace",
"David",
""
]
] | Using the parametrised representation of field theory (in which the location in spacetime of a part of a field is itself represented by a map from the base manifold to Minkowski spacetime) I demonstrate that in both local and global cases, internal (Yang-Mills-type) and spacetime (Poincar\'{e}) symmetries can be treated precisely on a par, so that gravitational theories may be regarded as gauge theories in a completely standard sense. |
1302.6658 | Shahar Hod | Shahar Hod | Cosmic Censorship: Formation of a Shielding Horizon Around a Fragile
Horizon | 4 pages | Physical Review D 87, 024037 (2013) | 10.1103/PhysRevD.87.024037 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The weak cosmic censorship conjecture asserts that spacetime singularities
that arise in gravitational collapse are always hidden inside of black holes,
invisible to distant observers. This conjecture, put forward by Penrose more
than four decades ago, is widely believed to be one of the basic principles of
nature. However, a complete proof of this hypothesis is still lacking and the
validity of the conjecture has therefore remained one of the most important
open questions in general relativity. In this study we analyze a gedanken
experiment which is designed to challenge cosmic censorship by trying to
overcharge a Reissner-Nordstr\"om black hole: a charged shell is lowered {\it
adiabatically} into the charged black hole. The mass-energy delivered to the
black hole can be red-shifted by letting the dropping point of the shell
approach the black-hole horizon. On the other hand, the electric charge of the
shell is not red-shifted by the gravitational field of the black hole. It
therefore seems, at first sight, that the charged shell is not hindered from
entering the black hole, overcharging it and removing its horizon. However, in
the present study we prove that the exposure of a naked singularity to distant
observers is actually excluded due to the formation of a new (and {\it larger})
horizon around the original black hole. Moreover, we shall prove that this new
horizon is already formed {\it before} the charged shell crosses the original
black-hole horizon. This result, which seems to have been previously
overlooked, guarantees the validity of the weak cosmic censorship conjecture in
this type of gedanken experiments.
| [
{
"created": "Wed, 27 Feb 2013 03:51:27 GMT",
"version": "v1"
}
] | 2015-06-15 | [
[
"Hod",
"Shahar",
""
]
] | The weak cosmic censorship conjecture asserts that spacetime singularities that arise in gravitational collapse are always hidden inside of black holes, invisible to distant observers. This conjecture, put forward by Penrose more than four decades ago, is widely believed to be one of the basic principles of nature. However, a complete proof of this hypothesis is still lacking and the validity of the conjecture has therefore remained one of the most important open questions in general relativity. In this study we analyze a gedanken experiment which is designed to challenge cosmic censorship by trying to overcharge a Reissner-Nordstr\"om black hole: a charged shell is lowered {\it adiabatically} into the charged black hole. The mass-energy delivered to the black hole can be red-shifted by letting the dropping point of the shell approach the black-hole horizon. On the other hand, the electric charge of the shell is not red-shifted by the gravitational field of the black hole. It therefore seems, at first sight, that the charged shell is not hindered from entering the black hole, overcharging it and removing its horizon. However, in the present study we prove that the exposure of a naked singularity to distant observers is actually excluded due to the formation of a new (and {\it larger}) horizon around the original black hole. Moreover, we shall prove that this new horizon is already formed {\it before} the charged shell crosses the original black-hole horizon. This result, which seems to have been previously overlooked, guarantees the validity of the weak cosmic censorship conjecture in this type of gedanken experiments. |
1909.10372 | Lijing Shao | Rui Xu, Junjie Zhao, Lijing Shao | Neutron Star Structure in the Minimal Gravitational Standard-Model
Extension and the Implication to Continuous Gravitational Waves | 9 pages, 2 figures; accepted by Physics Letters B | Physics Letters B 803 (2020) 135283 | 10.1016/j.physletb.2020.135283 | null | gr-qc astro-ph.HE hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Tiny violation of Lorentz invariance has been the subject of theoretic study
and experimental test for a long time. We use the Standard-Model Extension
(SME) framework to investigate the effect of the minimal Lorentz violation on
the structure of a neutron star. A set of hydrostatic equations with
modifications from Lorentz violation are derived, and then the modifications
are isolated and added to the Tolman-Oppenheimer-Volkoff (TOV) equation as the
leading-order Lorentz-violation corrections in relativistic systems. A
perturbation solution to the leading-order modified TOV equations is found. The
quadrupole moments due to the anisotropy in the structure of neutron stars are
calculated and used to estimate the quadrupole radiation of a spinning neutron
star with the same deformation. The calculation puts forward a new test for
Lorentz invariance in the strong-field regime when continuous gravitational
waves are observed in the future.
| [
{
"created": "Mon, 23 Sep 2019 13:59:56 GMT",
"version": "v1"
},
{
"created": "Sat, 8 Feb 2020 04:54:38 GMT",
"version": "v2"
}
] | 2020-02-17 | [
[
"Xu",
"Rui",
""
],
[
"Zhao",
"Junjie",
""
],
[
"Shao",
"Lijing",
""
]
] | Tiny violation of Lorentz invariance has been the subject of theoretic study and experimental test for a long time. We use the Standard-Model Extension (SME) framework to investigate the effect of the minimal Lorentz violation on the structure of a neutron star. A set of hydrostatic equations with modifications from Lorentz violation are derived, and then the modifications are isolated and added to the Tolman-Oppenheimer-Volkoff (TOV) equation as the leading-order Lorentz-violation corrections in relativistic systems. A perturbation solution to the leading-order modified TOV equations is found. The quadrupole moments due to the anisotropy in the structure of neutron stars are calculated and used to estimate the quadrupole radiation of a spinning neutron star with the same deformation. The calculation puts forward a new test for Lorentz invariance in the strong-field regime when continuous gravitational waves are observed in the future. |
1511.00491 | Burin Gumjudpai | Burin Gumjudpai (IF Naresuan) and Phongsaphat Rangdee (IF Naresuan) | Non-minimal derivative coupling gravity in cosmology | 11 pages, 2 figures with additional references and corrections | General Relativity and Gravitation 47 (2015) 140 | 10.1007/s10714-015-1985-2 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We give a brief review of the non-minimal derivative coupling (NMDC) scalar
field theory in which there is non-minimal coupling between the scalar field
derivative term and the Einstein tensor. We assume that the expansion is of
power-law type or super-acceleration type for small redshift. The Lagrangian
includes the NMDC term, a free kinetic term, a cosmological constant term and a
barotropic matter term. For a value of the coupling constant that is compatible
with inflation, we use the combined WMAP9 (WMAP9+eCMB+BAO+ $H_0$) dataset, the
PLANCK+WP dataset, and the PLANCK $TT,TE,EE$+lowP+Lensing+ext datasets to find
the value of the cosmological constant in the model. Modeling the expansion
with power-law gives a negative cosmological constants while the phantom
power-law (super-acceleration) expansion gives positive cosmological constant
with large error bar. The value obtained is of the same order as in the
$\Lambda$CDM model, since at late times the NMDC effect is tiny due to small
curvature.
| [
{
"created": "Mon, 2 Nov 2015 13:28:18 GMT",
"version": "v1"
},
{
"created": "Tue, 3 May 2016 06:07:42 GMT",
"version": "v2"
},
{
"created": "Sun, 12 Jan 2020 14:35:55 GMT",
"version": "v3"
}
] | 2020-01-14 | [
[
"Gumjudpai",
"Burin",
"",
"IF Naresuan"
],
[
"Rangdee",
"Phongsaphat",
"",
"IF Naresuan"
]
] | We give a brief review of the non-minimal derivative coupling (NMDC) scalar field theory in which there is non-minimal coupling between the scalar field derivative term and the Einstein tensor. We assume that the expansion is of power-law type or super-acceleration type for small redshift. The Lagrangian includes the NMDC term, a free kinetic term, a cosmological constant term and a barotropic matter term. For a value of the coupling constant that is compatible with inflation, we use the combined WMAP9 (WMAP9+eCMB+BAO+ $H_0$) dataset, the PLANCK+WP dataset, and the PLANCK $TT,TE,EE$+lowP+Lensing+ext datasets to find the value of the cosmological constant in the model. Modeling the expansion with power-law gives a negative cosmological constants while the phantom power-law (super-acceleration) expansion gives positive cosmological constant with large error bar. The value obtained is of the same order as in the $\Lambda$CDM model, since at late times the NMDC effect is tiny due to small curvature. |
1311.0239 | Jean-Pierre Lasota | M.A. Abramowicz, W. Klu\'zniak, and J.-P. Lasota | Mass of a Black Hole Firewall | 6 pages, version published in Phys. Rev. Lett | Phys. Rev. Lett. 112, 091301 (2014) | 10.1103/PhysRevLett.112.091301 | NSF-KITP-14-017 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Quantum entanglement of Hawking radiation has been supposed to give rise to a
Planck density "firewall" near the event horizon of old black holes. We show
that Planck density firewalls are excluded by Einstein's equations for black
holes of mass exceeding the Planck mass. We find an upper limit of $1/(8\pi M)$
to the surface density of a firewall in a Schwarzschild black hole of mass $M$,
translating for astrophysical black holes into a firewall density smaller than
Planck density by more than 30 orders of magnitude. A strict upper limit on the
firewall density is given by the Planck density times the ratio $M_{\rm
Pl}/(8\pi M)$.
| [
{
"created": "Fri, 1 Nov 2013 18:00:44 GMT",
"version": "v1"
},
{
"created": "Wed, 12 Feb 2014 10:05:26 GMT",
"version": "v2"
},
{
"created": "Wed, 5 Mar 2014 15:24:56 GMT",
"version": "v3"
}
] | 2014-03-06 | [
[
"Abramowicz",
"M. A.",
""
],
[
"Kluźniak",
"W.",
""
],
[
"Lasota",
"J. -P.",
""
]
] | Quantum entanglement of Hawking radiation has been supposed to give rise to a Planck density "firewall" near the event horizon of old black holes. We show that Planck density firewalls are excluded by Einstein's equations for black holes of mass exceeding the Planck mass. We find an upper limit of $1/(8\pi M)$ to the surface density of a firewall in a Schwarzschild black hole of mass $M$, translating for astrophysical black holes into a firewall density smaller than Planck density by more than 30 orders of magnitude. A strict upper limit on the firewall density is given by the Planck density times the ratio $M_{\rm Pl}/(8\pi M)$. |
2403.14596 | Pedro Fernandes | Pedro G. S. Fernandes, Clare Burrage, Astrid Eichhorn, Thomas P.
Sotiriou | Shadows and Properties of Spin-Induced Scalarized Black Holes with and
without a Ricci Coupling | 8 pages, 6 figures | null | null | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we explore the properties and shadows of spin-induced
scalarized black holes, as well as investigate how a Ricci coupling influences
them. Our findings reveal significant deviations from the Kerr metric in terms
of the location and geodesic frequencies of the innermost stable circular orbit
and light ring, with the former exhibiting more pronounced disparities. The
shadows of scalarized black holes exhibit relatively minor deviations when
compared to those of Kerr black holes with the same mass and spin. Overall, the
presence of a Ricci coupling is observed to mitigate deviations from the Kerr
metric.
| [
{
"created": "Thu, 21 Mar 2024 17:49:53 GMT",
"version": "v1"
}
] | 2024-03-22 | [
[
"Fernandes",
"Pedro G. S.",
""
],
[
"Burrage",
"Clare",
""
],
[
"Eichhorn",
"Astrid",
""
],
[
"Sotiriou",
"Thomas P.",
""
]
] | In this work, we explore the properties and shadows of spin-induced scalarized black holes, as well as investigate how a Ricci coupling influences them. Our findings reveal significant deviations from the Kerr metric in terms of the location and geodesic frequencies of the innermost stable circular orbit and light ring, with the former exhibiting more pronounced disparities. The shadows of scalarized black holes exhibit relatively minor deviations when compared to those of Kerr black holes with the same mass and spin. Overall, the presence of a Ricci coupling is observed to mitigate deviations from the Kerr metric. |
1308.1521 | Nigel Bishop | Nigel T Bishop and Christian Reisswig | The gravitational wave strain in the characteristic formalism of
numerical relativity | 9 pages, 3 figures | General Relativity and Gravitation (2014) 46:1643 | 10.1007/s10714-013-1643-5 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The extraction of the gravitational wave signal, within the context of a
characteristic numerical evolution is revisited. A formula for the
gravitational wave strain is developed and tested, and is made publicly
available as part of the PITT code within the Einstein Toolkit. Using the new
strain formula, we show that artificial non-linear drifts inherent in time
integrated waveforms can be reduced for the case of a binary black hole merger
configuration. For the test case of a rapidly spinning stellar core collapse
model, however, we find that the drift must have different roots.
| [
{
"created": "Wed, 7 Aug 2013 09:45:53 GMT",
"version": "v1"
},
{
"created": "Tue, 17 Dec 2013 13:26:40 GMT",
"version": "v2"
}
] | 2013-12-18 | [
[
"Bishop",
"Nigel T",
""
],
[
"Reisswig",
"Christian",
""
]
] | The extraction of the gravitational wave signal, within the context of a characteristic numerical evolution is revisited. A formula for the gravitational wave strain is developed and tested, and is made publicly available as part of the PITT code within the Einstein Toolkit. Using the new strain formula, we show that artificial non-linear drifts inherent in time integrated waveforms can be reduced for the case of a binary black hole merger configuration. For the test case of a rapidly spinning stellar core collapse model, however, we find that the drift must have different roots. |
gr-qc/9507045 | Maria Bento | M.C. Bento and O. Bertolami | Constraints on Supergravity Chaotic Inflationary Models | Latex file, 10 pages; important changes and references added | Phys.Lett. B365 (1996) 59-63 | 10.1016/0370-2693(95)01169-2 | CERN-TH/95-199, DFTT 44/95 | gr-qc | null | We discuss, in the context of $N=1$ hidden sector non-minimal supergravity
chaotic inflationary models, constraints on the parameters of a polynomial
superpotential resulting from existing bounds on the reheating temperature and
on the amplitude of the primordial energy density fluctuations as inferred from
COBE. We present a specific two-parameter chaotic inflationary model which
satisfies these constraints and discuss a possible scenario for adequate baryon
asymmetry generation.
| [
{
"created": "Sat, 22 Jul 1995 13:55:57 GMT",
"version": "v1"
},
{
"created": "Wed, 25 Oct 1995 16:25:04 GMT",
"version": "v2"
}
] | 2009-10-28 | [
[
"Bento",
"M. C.",
""
],
[
"Bertolami",
"O.",
""
]
] | We discuss, in the context of $N=1$ hidden sector non-minimal supergravity chaotic inflationary models, constraints on the parameters of a polynomial superpotential resulting from existing bounds on the reheating temperature and on the amplitude of the primordial energy density fluctuations as inferred from COBE. We present a specific two-parameter chaotic inflationary model which satisfies these constraints and discuss a possible scenario for adequate baryon asymmetry generation. |
gr-qc/9708038 | Simon Hern | S. D. Hern and J. M. Stewart (DAMTP, Cambridge) | The Gowdy T3 Cosmologies revisited | 11 pages, LaTeX, 6 figures, results and conclusions revised and
(considerably) expanded | Class.Quant.Grav. 15 (1998) 1581-1593 | 10.1088/0264-9381/15/6/014 | R-97/41 | gr-qc | null | We have examined, repeated and extended earlier numerical calculations of
Berger and Moncrief for the evolution of unpolarized Gowdy T3 cosmological
models. Our results are consistent with theirs and we support their claim that
the models exhibit AVTD behaviour, even though spatial derivatives cannot be
neglected. The behaviour of the curvature invariants and the formation of
structure through evolution both backwards and forwards in time is discussed.
| [
{
"created": "Mon, 18 Aug 1997 17:18:36 GMT",
"version": "v1"
},
{
"created": "Tue, 5 May 1998 14:09:07 GMT",
"version": "v2"
}
] | 2009-10-30 | [
[
"Hern",
"S. D.",
"",
"DAMTP, Cambridge"
],
[
"Stewart",
"J. M.",
"",
"DAMTP, Cambridge"
]
] | We have examined, repeated and extended earlier numerical calculations of Berger and Moncrief for the evolution of unpolarized Gowdy T3 cosmological models. Our results are consistent with theirs and we support their claim that the models exhibit AVTD behaviour, even though spatial derivatives cannot be neglected. The behaviour of the curvature invariants and the formation of structure through evolution both backwards and forwards in time is discussed. |
1411.7402 | Anja Marunovic | Anja Marunovic and Tomislav Prokopec | Global monopoles can change Universe's topology | 5 pages, 1 figure; introduction changed; matches published version | null | 10.1016/j.physletb.2016.03.030 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | If the Universe undergoes a phase transition, at which global monopoles are
created or destroyed, topology of its spatial sections can change. More
specifically, by making use of Myers' theorem, we show that, after a transition
in which global monopoles form, spatial sections of a spatially flat Universe
become finite and closed. This implies that global monopoles can change
topology of Universe's spatial sections (from infinite and open to finite and
closed). We emphasize that global monopoles cannot alter topology of the
space-time manifold.
| [
{
"created": "Wed, 26 Nov 2014 21:29:11 GMT",
"version": "v1"
},
{
"created": "Mon, 8 Dec 2014 16:38:14 GMT",
"version": "v2"
},
{
"created": "Thu, 17 Mar 2016 17:04:24 GMT",
"version": "v3"
}
] | 2017-03-15 | [
[
"Marunovic",
"Anja",
""
],
[
"Prokopec",
"Tomislav",
""
]
] | If the Universe undergoes a phase transition, at which global monopoles are created or destroyed, topology of its spatial sections can change. More specifically, by making use of Myers' theorem, we show that, after a transition in which global monopoles form, spatial sections of a spatially flat Universe become finite and closed. This implies that global monopoles can change topology of Universe's spatial sections (from infinite and open to finite and closed). We emphasize that global monopoles cannot alter topology of the space-time manifold. |
0903.4395 | Leonid Grishchuk P | L P Grishchuk | Some Uncomfortable Thoughts on the Nature of Gravity, Cosmology, and the
Early Universe | 16 pages, including 4 figures and 2 photographs. Contribution to the
'Nature of Gravity' conference at the International Space Science Institute,
October 2008, Bern, Switzerland; v.2 takes into account the referee comments,
to be published in Space Science Reviews | Space Sci.Rev.148:315-328,2009 | 10.1007/s11214-009-9509-6 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A specific theoretical framework is important for designing and conducting an
experiment, and for interpretation of its results. The field of gravitational
physics is expanding, and more clarity is needed. It appears that some popular
notions, such as `inflation' and `gravity is geometry', have become more like
liabilities than assets. A critical analysis is presented and the ways out of
the difficulties are proposed.
| [
{
"created": "Wed, 25 Mar 2009 18:11:54 GMT",
"version": "v1"
},
{
"created": "Sun, 12 Apr 2009 17:34:15 GMT",
"version": "v2"
}
] | 2014-11-18 | [
[
"Grishchuk",
"L P",
""
]
] | A specific theoretical framework is important for designing and conducting an experiment, and for interpretation of its results. The field of gravitational physics is expanding, and more clarity is needed. It appears that some popular notions, such as `inflation' and `gravity is geometry', have become more like liabilities than assets. A critical analysis is presented and the ways out of the difficulties are proposed. |
0811.4178 | Rosales Garcia J.Juan | J.J. Rosales and V.I. Tkach | Supersymmetric Cosmology and Dark Energy | This article is a contribution to the anniversary volume "The
Problems of Modern Cosmology". On the occasion of the 50th birthday of Prof.
S.D. Odintsov. Editor Prof. P.M. Lavrov | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using the superfield approach we construct the n = 2 supersymmetric
lagrangian for the FRW Universe with perfect fluid as matter fields. The
obtained supersymmetric algebra allowed us to take the square root of the
Wheeler-DeWitt equation and solve the corresponding quantum constraint. This
model leads to the relation between the vacuum energy density and the energy
density of the dust matter.
| [
{
"created": "Tue, 25 Nov 2008 21:08:17 GMT",
"version": "v1"
}
] | 2008-11-27 | [
[
"Rosales",
"J. J.",
""
],
[
"Tkach",
"V. I.",
""
]
] | Using the superfield approach we construct the n = 2 supersymmetric lagrangian for the FRW Universe with perfect fluid as matter fields. The obtained supersymmetric algebra allowed us to take the square root of the Wheeler-DeWitt equation and solve the corresponding quantum constraint. This model leads to the relation between the vacuum energy density and the energy density of the dust matter. |
gr-qc/0603033 | Martin Tajmar | M. Tajmar, F. Plesescu, K. Marhold, C.J. de Matos | Experimental Detection of the Gravitomagnetic London Moment | Submitted to Physica C | null | null | null | gr-qc | null | It is well known that a rotating superconductor produces a magnetic field
proportional to its angular velocity. The authors conjectured earlier, that in
addition to this so-called London moment, also a large gravitomagnetic field
should appear to explain an apparent mass increase of Niobium Cooper-pairs.
This phenomenon was indeed observed and induced acceleration fields outside the
superconductor in the order of about 10^-4 g were found. The field appears to
be directly proportional to the applied angular acceleration of the
superconductor following our theoretical motivations. If confirmed, a
gravitomagnetic field of measurable magnitude was produced for the first time
in a laboratory environment. These results may open up a new experimental
window on testing general relativity and its consequences using coherent
matter.
| [
{
"created": "Thu, 9 Mar 2006 18:41:11 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Tajmar",
"M.",
""
],
[
"Plesescu",
"F.",
""
],
[
"Marhold",
"K.",
""
],
[
"de Matos",
"C. J.",
""
]
] | It is well known that a rotating superconductor produces a magnetic field proportional to its angular velocity. The authors conjectured earlier, that in addition to this so-called London moment, also a large gravitomagnetic field should appear to explain an apparent mass increase of Niobium Cooper-pairs. This phenomenon was indeed observed and induced acceleration fields outside the superconductor in the order of about 10^-4 g were found. The field appears to be directly proportional to the applied angular acceleration of the superconductor following our theoretical motivations. If confirmed, a gravitomagnetic field of measurable magnitude was produced for the first time in a laboratory environment. These results may open up a new experimental window on testing general relativity and its consequences using coherent matter. |
gr-qc/0105087 | Angelo Tartaglia | A. Tartaglia, M.L. Ruggiero | A comment on a proposal to use neutrons to reveal gravitomagnetic
effects on Earth | 1 page, Latex | null | null | null | gr-qc | null | Arguments are presented which show that the recent proposals of using
neutrons to test gravitomagnetic effects on Earth are impracticable.
| [
{
"created": "Thu, 24 May 2001 13:41:14 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Tartaglia",
"A.",
""
],
[
"Ruggiero",
"M. L.",
""
]
] | Arguments are presented which show that the recent proposals of using neutrons to test gravitomagnetic effects on Earth are impracticable. |
gr-qc/0601127 | James Mattingly | James Mattingly | Why Eppley and Hannah's Experiment Isn't | 10 pages | Phys.Rev. D73 (2006) 064025 | 10.1103/PhysRevD.73.064025 | null | gr-qc | null | It is shown that Eppley and Hannah's thought experiment establishing that
gravity must be quantized is fatally flawed. The device they propose, even if
built, cannot establish their claims, nor is it plausible that it can be built
with any materials compatible with the values of c, h, and G. Finally the
device, and any reasonable modification of it, would be so massive as to be
within its own Schwarzschild radius--a fatal flaw for any thought experiment.
| [
{
"created": "Sun, 29 Jan 2006 01:17:07 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Mattingly",
"James",
""
]
] | It is shown that Eppley and Hannah's thought experiment establishing that gravity must be quantized is fatally flawed. The device they propose, even if built, cannot establish their claims, nor is it plausible that it can be built with any materials compatible with the values of c, h, and G. Finally the device, and any reasonable modification of it, would be so massive as to be within its own Schwarzschild radius--a fatal flaw for any thought experiment. |
2211.10736 | Hermano Velten | Diego Santos de Jesus, Hermano Velten and Federico Piazza | Constraining the anomalous coupling of gravitational waves with double
pulsar | 5 pages, 2 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We revisit the decay of the orbital period in binary systems that occurs due
to the emission of gravitational waves in the context of modified gravity
models where the coupling $G_{gw}$ between matter and on-shell gravitons is
allowed to differ from the Newton constant $G_N$. Using the most precise
orbital parameters of binary pulsars, those of the Double Pulsar, we constrain
the ratio $G_{gw}/G_N$ to the level of $10^{-4}$, improving by two orders of
magnitude the present bound on this quantity.
| [
{
"created": "Sat, 19 Nov 2022 16:12:14 GMT",
"version": "v1"
}
] | 2022-11-22 | [
[
"de Jesus",
"Diego Santos",
""
],
[
"Velten",
"Hermano",
""
],
[
"Piazza",
"Federico",
""
]
] | We revisit the decay of the orbital period in binary systems that occurs due to the emission of gravitational waves in the context of modified gravity models where the coupling $G_{gw}$ between matter and on-shell gravitons is allowed to differ from the Newton constant $G_N$. Using the most precise orbital parameters of binary pulsars, those of the Double Pulsar, we constrain the ratio $G_{gw}/G_N$ to the level of $10^{-4}$, improving by two orders of magnitude the present bound on this quantity. |
2011.13586 | Lang Liu | Lang Liu, {\O}yvind Christiansen, Wen-Hong Ruan, Zong-Kuan Guo,
Rong-Gen Cai and Sang Pyo Kim | Gravitational and electromagnetic radiation from binary black holes with
electric and magnetic charges: Elliptical orbits on a cone | 10 pages, 2 figures, a new section added | Eur.Phys.J. C (2021) | 10.1140/epjc/s10052-021-09849-4 | null | gr-qc hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Extending the electromagnetic and gravitational radiations from binary black
holes with electric and magnetic charges in circular orbits in Phys. Rev. D
{\bf 102}, 103520 (2020), we calculate the total emission rates of energy and
angular momentum due to gravitational and electromagnetic radiations from
dyonic binary black holes in precessing elliptical orbits. It is shown that the
emission rates of energy and angular momentum due to gravitational and
electromagnetic radiations have the same dependence on the conic angle for
different orbits. Moreover, we obtain the evolutions of orbits and find that a
circular orbit remains circular while an elliptic orbit becomes quasi-circular
due to electromagnetic and gravitational radiations. Using the evolution of
orbits, we derive the waveform models for dyonic binary black hole inspirals
and show the amplitudes of the gravitational waves for dyonic binary black hole
inspirals differ from those for Schwarzschild binary black hole inspirals,
which can be used to test electric and magnetic charges of black holes.
| [
{
"created": "Fri, 27 Nov 2020 07:23:23 GMT",
"version": "v1"
},
{
"created": "Wed, 1 Dec 2021 03:37:57 GMT",
"version": "v2"
}
] | 2021-12-02 | [
[
"Liu",
"Lang",
""
],
[
"Christiansen",
"Øyvind",
""
],
[
"Ruan",
"Wen-Hong",
""
],
[
"Guo",
"Zong-Kuan",
""
],
[
"Cai",
"Rong-Gen",
""
],
[
"Kim",
"Sang Pyo",
""
]
] | Extending the electromagnetic and gravitational radiations from binary black holes with electric and magnetic charges in circular orbits in Phys. Rev. D {\bf 102}, 103520 (2020), we calculate the total emission rates of energy and angular momentum due to gravitational and electromagnetic radiations from dyonic binary black holes in precessing elliptical orbits. It is shown that the emission rates of energy and angular momentum due to gravitational and electromagnetic radiations have the same dependence on the conic angle for different orbits. Moreover, we obtain the evolutions of orbits and find that a circular orbit remains circular while an elliptic orbit becomes quasi-circular due to electromagnetic and gravitational radiations. Using the evolution of orbits, we derive the waveform models for dyonic binary black hole inspirals and show the amplitudes of the gravitational waves for dyonic binary black hole inspirals differ from those for Schwarzschild binary black hole inspirals, which can be used to test electric and magnetic charges of black holes. |
2201.03365 | Reggie Pantig | Reggie C. Pantig, Ali \"Ovg\"un | Dark matter effect on the weak deflection angle by black holes at the
center of Milky Way and M87 galaxies | 11 pages, 9 figures. Corrected some typos, added Einstein ring
discussion | Eur. Phys. J. C (2022) 82:391 | 10.1140/epjc/s10052-022-10319-8 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we investigated the effect of dark matter on the weak
deflection angle by black holes at the galactic center. We consider three known
dark matter density profiles such as the Cold Dark Matter (CDM), Scalar Field
Dark Matter (SFDM), and the Universal Rotation Curve (URC) from the Burkert
profile. To achieve this goal, we used how the positional angles are measured
by Ishihara et al. method based on Gauss-Bonnet theorem (GBT) on the optical
metric. With the help of the non-asymptotic form of the GBT, the longitudinal
angle difference is also calculated. First, we find the emergence of apparent
divergent terms on the said profiles, which indicates that the spacetime
describing the black hole-dark matter combination is non-asymptotic. We showed
that these apparent divergent terms vanish when the distance of the source and
receiver are astronomically distant from the black hole. Using the current
observational data in the Milky Way and M87 galaxies, we find interesting
behaviors of how the weak deflection angle varies with the impact parameter,
which gives us some hint on how dark matter interacts with the null particles
for each dark matter density profile. We conclude that since these deviations
are evident near the dark matter core radius, the weak deflection angle offers
a better alternative for dark matter detection than using the deviation from
the black hole shadow. With the DM profiles explored in this study, we find
that SFDM is the most difficult to detect, while the easiest is the URC
profile. With the dark matter profiles explored in this study, we find that the
variation of the values for weak deflection angle strongly depends on the dark
matter mass on a particular profile.
| [
{
"created": "Mon, 10 Jan 2022 14:30:38 GMT",
"version": "v1"
},
{
"created": "Sat, 5 Feb 2022 23:59:57 GMT",
"version": "v2"
},
{
"created": "Thu, 24 Feb 2022 08:05:37 GMT",
"version": "v3"
}
] | 2022-05-04 | [
[
"Pantig",
"Reggie C.",
""
],
[
"Övgün",
"Ali",
""
]
] | In this paper, we investigated the effect of dark matter on the weak deflection angle by black holes at the galactic center. We consider three known dark matter density profiles such as the Cold Dark Matter (CDM), Scalar Field Dark Matter (SFDM), and the Universal Rotation Curve (URC) from the Burkert profile. To achieve this goal, we used how the positional angles are measured by Ishihara et al. method based on Gauss-Bonnet theorem (GBT) on the optical metric. With the help of the non-asymptotic form of the GBT, the longitudinal angle difference is also calculated. First, we find the emergence of apparent divergent terms on the said profiles, which indicates that the spacetime describing the black hole-dark matter combination is non-asymptotic. We showed that these apparent divergent terms vanish when the distance of the source and receiver are astronomically distant from the black hole. Using the current observational data in the Milky Way and M87 galaxies, we find interesting behaviors of how the weak deflection angle varies with the impact parameter, which gives us some hint on how dark matter interacts with the null particles for each dark matter density profile. We conclude that since these deviations are evident near the dark matter core radius, the weak deflection angle offers a better alternative for dark matter detection than using the deviation from the black hole shadow. With the DM profiles explored in this study, we find that SFDM is the most difficult to detect, while the easiest is the URC profile. With the dark matter profiles explored in this study, we find that the variation of the values for weak deflection angle strongly depends on the dark matter mass on a particular profile. |
2206.00721 | Vasilis Oikonomou | V.K. Oikonomou, Eirini C. Lymperiadou | Effects of a Geometrically Realized Early Dark Energy Era on the
Spectrum of Primordial Gravitational Waves | Accepted in Symmetry, invited article | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we investigate the effects of a geometrically generated early
dark energy era on the energy spectrum of the primordial gravitational waves.
The early dark energy era, which we choose it to have a constant equation of
state parameter $w$, is synergistically generated by an appropriate $f(R)$
gravity in the presence of matter and radiation perfect fluids. As we
demonstrate, the predicted signal for the energy spectrum of the $f(R)$
primordial gravitational waves is amplified and can be detectable, for various
reheating temperatures, especially for large reheating temperatures. The signal
amplitude depends on the duration of the early dark energy era and on the value
of the dark energy equation of state parameter, with the most latter affecting
more crucially the amplification. Specifically the amplification occurs when
the equation of state parameter approaches the de Sitter value $w=-1$.
Regarding the duration of the early dark energy era, we find that the largest
amplification occurs when the early dark energy era commences at a temperature
$T=0.85\,$eV until $T=7.8\,$eV. Moreover we study a similar scenario in which
amplification occurs, where the early dark energy era commences at $T=0.29\,$eV
and lasts until the temperature is increased by $\Delta T\sim 1.7\,$eV.
| [
{
"created": "Wed, 1 Jun 2022 19:18:17 GMT",
"version": "v1"
}
] | 2022-06-03 | [
[
"Oikonomou",
"V. K.",
""
],
[
"Lymperiadou",
"Eirini C.",
""
]
] | In this work we investigate the effects of a geometrically generated early dark energy era on the energy spectrum of the primordial gravitational waves. The early dark energy era, which we choose it to have a constant equation of state parameter $w$, is synergistically generated by an appropriate $f(R)$ gravity in the presence of matter and radiation perfect fluids. As we demonstrate, the predicted signal for the energy spectrum of the $f(R)$ primordial gravitational waves is amplified and can be detectable, for various reheating temperatures, especially for large reheating temperatures. The signal amplitude depends on the duration of the early dark energy era and on the value of the dark energy equation of state parameter, with the most latter affecting more crucially the amplification. Specifically the amplification occurs when the equation of state parameter approaches the de Sitter value $w=-1$. Regarding the duration of the early dark energy era, we find that the largest amplification occurs when the early dark energy era commences at a temperature $T=0.85\,$eV until $T=7.8\,$eV. Moreover we study a similar scenario in which amplification occurs, where the early dark energy era commences at $T=0.29\,$eV and lasts until the temperature is increased by $\Delta T\sim 1.7\,$eV. |
1901.03746 | Naeem Ahmad Pundeer Pundeer | Musavvir Ali, Naeem Ahmad Pundeer and Zafar Ahsan | Semiconformal symmetry- A new symmetry of the spacetime manifold of the
general relativity | null | null | 10.22436/jmcs.020.03.07 | null | gr-qc | http://creativecommons.org/publicdomain/zero/1.0/ | In this paper we have introduced a new symmetry property of spacetime which
is named as semiconformal curvature collineation, and its relationship with
other known symmetry properties has been established. This new symmetry
property of the spacetime has also been studied for non-null and null
electromagnetic fields.
| [
{
"created": "Thu, 10 Jan 2019 07:34:36 GMT",
"version": "v1"
}
] | 2023-05-30 | [
[
"Ali",
"Musavvir",
""
],
[
"Pundeer",
"Naeem Ahmad",
""
],
[
"Ahsan",
"Zafar",
""
]
] | In this paper we have introduced a new symmetry property of spacetime which is named as semiconformal curvature collineation, and its relationship with other known symmetry properties has been established. This new symmetry property of the spacetime has also been studied for non-null and null electromagnetic fields. |
1807.08310 | Itzhak Bars | Itzhak Bars | Wavefunction for the Universe Circa the Beginning with Dynamically
Determined Unique Initial Conditions | 40 pages, 9 figures. Version 2 has a new subsection VIII-D, and also
contains some minor corrections and additions | Phys. Rev. D 98, 103510 (2018) | 10.1103/PhysRevD.98.103510 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper I will first outline an effective field theory for cosmology
(EFTC) that is based on the Standard Model coupled to General Relativity and
improved with Weyl symmetry. There are no new physical degrees of freedom in
this theory, but what is new is an enlargement of the domain of the existing
physical fields and of spacetime via the larger symmetry, thus curing the
geodesic incompleteness of the traditional theory. Invoking the softer behavior
of an underlying theory of quantum gravity, I further argue that it is
reasonable to ban higher curvature terms in the effective action, thus making
this EFTC mathematically well behaved at gravitational singularities, as well
as geodesically complete, thus able to make new physics predictions. Using this
EFTC, I show some predictions of surprising behavior of the universe at
singularities including a unique set of big-bang initial conditions that emerge
from a dynamical attractor mechanism. I will illustrate this behavior with
detailed formulas and plots of the classical solutions and the quantum
wavefunction that are continuous across singularities for a cosmology that
includes the past and future of the big bang. The solutions are given in the
geodesically complete global mini-superspace that is similar to the extended
spacetime of a black hole or extended Rindler spacetime. The analytic
continuation of the quantum wavefunction across the horizons describes the
passage through the singularities. This analytic continuation solves a
long-standing problem of the singular (-1/r^2) potential in quantum mechanics
that dates back to Von Neumann. The analytic properties of the wavefunction
also reveal an infinite stack of universes sewn together at the horizons of the
geodesically complete space. Finally a critique of recent controversial papers
using the path integral approach in cosmology is given.
| [
{
"created": "Sun, 22 Jul 2018 16:19:17 GMT",
"version": "v1"
},
{
"created": "Sat, 6 Oct 2018 09:49:27 GMT",
"version": "v2"
}
] | 2018-11-21 | [
[
"Bars",
"Itzhak",
""
]
] | In this paper I will first outline an effective field theory for cosmology (EFTC) that is based on the Standard Model coupled to General Relativity and improved with Weyl symmetry. There are no new physical degrees of freedom in this theory, but what is new is an enlargement of the domain of the existing physical fields and of spacetime via the larger symmetry, thus curing the geodesic incompleteness of the traditional theory. Invoking the softer behavior of an underlying theory of quantum gravity, I further argue that it is reasonable to ban higher curvature terms in the effective action, thus making this EFTC mathematically well behaved at gravitational singularities, as well as geodesically complete, thus able to make new physics predictions. Using this EFTC, I show some predictions of surprising behavior of the universe at singularities including a unique set of big-bang initial conditions that emerge from a dynamical attractor mechanism. I will illustrate this behavior with detailed formulas and plots of the classical solutions and the quantum wavefunction that are continuous across singularities for a cosmology that includes the past and future of the big bang. The solutions are given in the geodesically complete global mini-superspace that is similar to the extended spacetime of a black hole or extended Rindler spacetime. The analytic continuation of the quantum wavefunction across the horizons describes the passage through the singularities. This analytic continuation solves a long-standing problem of the singular (-1/r^2) potential in quantum mechanics that dates back to Von Neumann. The analytic properties of the wavefunction also reveal an infinite stack of universes sewn together at the horizons of the geodesically complete space. Finally a critique of recent controversial papers using the path integral approach in cosmology is given. |
1904.06503 | Hao Xu | Hao Xu, Man-Hong Yung | Black hole evaporation in Lovelock gravity with diverse dimensions | 6 pages + references, 3 figures;minor corrections, references added,
published version | Physics Letters B 794 (2019) 77-82 | 10.1016/j.physletb.2019.05.031 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the black hole evaporation process in Lovelock gravity with
diverse dimensions. By selecting the appropriate coefficients, the space-time
solutions can possess a unique AdS vacuum with a fixed cosmological constant
$\Lambda=-\frac{(d-1)(d-2)}{2\ell^{2}}$. The black hole solutions can be
divided into two cases: $d>2k+1$ and $d=2k+1$. In the case of $d>2k+1$, the
black hole is in an analogy with the Schwarzschild AdS black hole, and the life
time is bounded by a time of the order of $\ell^{d-2k+1}$, which reduces Page's
result on the Einstein gravity in $k=1$. In the case of $d=2k+1$, the black
hole resembles the three dimensional black hole. The black hole vacuum
corresponds to $T=0$, so the black hole will take infinite time to evaporate
away for any initial states, which obeys the third law of thermodynamics. In
the asymptotically flat limit $\ell\rightarrow \infty$, the system reduces to
the pure Lovelock gravity that only possesses the highest $k$-th order term.
For a initial mass $M_0$, the life time of the black hole is in the order of
$M_0^{\frac{d-2k+1}{d-2k-1}}$.
| [
{
"created": "Sat, 13 Apr 2019 08:14:54 GMT",
"version": "v1"
},
{
"created": "Thu, 30 May 2019 05:53:33 GMT",
"version": "v2"
}
] | 2019-05-31 | [
[
"Xu",
"Hao",
""
],
[
"Yung",
"Man-Hong",
""
]
] | We investigate the black hole evaporation process in Lovelock gravity with diverse dimensions. By selecting the appropriate coefficients, the space-time solutions can possess a unique AdS vacuum with a fixed cosmological constant $\Lambda=-\frac{(d-1)(d-2)}{2\ell^{2}}$. The black hole solutions can be divided into two cases: $d>2k+1$ and $d=2k+1$. In the case of $d>2k+1$, the black hole is in an analogy with the Schwarzschild AdS black hole, and the life time is bounded by a time of the order of $\ell^{d-2k+1}$, which reduces Page's result on the Einstein gravity in $k=1$. In the case of $d=2k+1$, the black hole resembles the three dimensional black hole. The black hole vacuum corresponds to $T=0$, so the black hole will take infinite time to evaporate away for any initial states, which obeys the third law of thermodynamics. In the asymptotically flat limit $\ell\rightarrow \infty$, the system reduces to the pure Lovelock gravity that only possesses the highest $k$-th order term. For a initial mass $M_0$, the life time of the black hole is in the order of $M_0^{\frac{d-2k+1}{d-2k-1}}$. |
gr-qc/0512042 | Piotr T. Chru\'sciel | Piotr T. Chrusciel, Daniel Maerten | Killing vectors in asymptotically flat space--times: II. Asymptotically
translational Killing vectors and the rigid positive energy theorem in higher
dimensions | null | J.Math.Phys. 47 (2006) 022502 | 10.1063/1.2167809 | Newton Institute preprint NI05062-GMR | gr-qc | null | We show that the borderline cases in the proof of the positive energy theorem
for initial data sets, on spin manifolds, in dimensions $n\ge 3$, are only
possible for initial data arising from embeddings in Minkowski space-time.
| [
{
"created": "Tue, 6 Dec 2005 20:20:38 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Chrusciel",
"Piotr T.",
""
],
[
"Maerten",
"Daniel",
""
]
] | We show that the borderline cases in the proof of the positive energy theorem for initial data sets, on spin manifolds, in dimensions $n\ge 3$, are only possible for initial data arising from embeddings in Minkowski space-time. |
gr-qc/0005047 | Robert Beig | Robert Beig, Bernd G. Schmidt | Time-Independent Gravitational Fields | 47 pages, LaTeX, uses Springer cl2emult style | Lect.Notes Phys.540:325-372,2000 | null | UWThPh1999-1 | gr-qc | null | This article reviews, from a global point of view, rigorous results on time
independent spacetimes. Throughout attention is confined to isolated bodies at
rest or in uniform rotation in an otherwise empty universe. The discussion
starts from first principles and is, as much as possible, self-contained.
| [
{
"created": "Sat, 13 May 2000 08:16:11 GMT",
"version": "v1"
}
] | 2011-08-11 | [
[
"Beig",
"Robert",
""
],
[
"Schmidt",
"Bernd G.",
""
]
] | This article reviews, from a global point of view, rigorous results on time independent spacetimes. Throughout attention is confined to isolated bodies at rest or in uniform rotation in an otherwise empty universe. The discussion starts from first principles and is, as much as possible, self-contained. |
gr-qc/9506066 | null | Giampiero Esposito, Alexander Yu. Kamenshchik, Igor V. Mishakov,
Giuseppe Pollifrone | Gravitons in One-Loop Quantum Cosmology: Correspondence Between
Covariant and Non-Covariant Formalisms | 29 pages, latex, recently appearing in Physical Review D, volume 50,
pages 6329-6337, November 1994. The authors apologize for the delay in
circulating the paper, due to technical problems now fixed | Phys.Rev. D50 (1994) 6329-6337 | 10.1103/PhysRevD.50.6329 | DSF 94/14 | gr-qc | null | The discrepancy between the results of covariant and non-covariant one-loop
calculations for higher-spin fields in quantum cosmology is analyzed. A
detailed mode-by-mode study of perturbative quantum gravity about a flat
Euclidean background bounded by two concentric 3-spheres, including
non-physical degrees of freedom and ghost modes, leads to one-loop amplitudes
in agreement with the covariant Schwinger-DeWitt method. This calculation
provides the generalization of a previous analysis of fermionic fields and
electromagnetic fields at one-loop about flat Euclidean backgrounds admitting a
well-defined 3+1 decomposition.
| [
{
"created": "Wed, 28 Jun 1995 06:47:27 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Esposito",
"Giampiero",
""
],
[
"Kamenshchik",
"Alexander Yu.",
""
],
[
"Mishakov",
"Igor V.",
""
],
[
"Pollifrone",
"Giuseppe",
""
]
] | The discrepancy between the results of covariant and non-covariant one-loop calculations for higher-spin fields in quantum cosmology is analyzed. A detailed mode-by-mode study of perturbative quantum gravity about a flat Euclidean background bounded by two concentric 3-spheres, including non-physical degrees of freedom and ghost modes, leads to one-loop amplitudes in agreement with the covariant Schwinger-DeWitt method. This calculation provides the generalization of a previous analysis of fermionic fields and electromagnetic fields at one-loop about flat Euclidean backgrounds admitting a well-defined 3+1 decomposition. |
gr-qc/9411001 | Erik A. Martinez | Valeri Frolov and Erik A. Martinez | Action and Hamiltonian for eternal black holes | 24 pages, Revtex, 5 figures (available upon request) | Class.Quant.Grav. 13 (1996) 481-496 | 10.1088/0264-9381/13/3/013 | Alberta-Thy-32-94 | gr-qc hep-th | null | We present the Hamiltonian, quasilocal energy, and angular momentum for a
spacetime region spatially bounded by two timelike surfaces. The results are
applied to the particular case of a spacetime representing an eternal black
hole. It is shown that in the case when the boundaries are located in two
different wedges of the Kruskal diagram, the Hamiltonian is of the form $H =
H_+ - H_-$, where $H_+$ and $H_-$ are the Hamiltonian functions for the right
and left wedges respectively. The application of the obtained results to the
thermofield dynamics description of quantum effects in black holes is briefly
discussed.
| [
{
"created": "Tue, 1 Nov 1994 15:30:17 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Frolov",
"Valeri",
""
],
[
"Martinez",
"Erik A.",
""
]
] | We present the Hamiltonian, quasilocal energy, and angular momentum for a spacetime region spatially bounded by two timelike surfaces. The results are applied to the particular case of a spacetime representing an eternal black hole. It is shown that in the case when the boundaries are located in two different wedges of the Kruskal diagram, the Hamiltonian is of the form $H = H_+ - H_-$, where $H_+$ and $H_-$ are the Hamiltonian functions for the right and left wedges respectively. The application of the obtained results to the thermofield dynamics description of quantum effects in black holes is briefly discussed. |
1509.09086 | Beatriz Elizaga Navascu\'es | Jer\'onimo Cortez, Beatriz Elizaga Navascu\'es, Mercedes
Mart\'in-Benito, Guillermo A. Mena Marug\'an, and Jos\'e M. Velhinho | Unitary evolution and uniqueness of the Fock representation of Dirac
fields in cosmological spacetimes | 24 pages | Phys. Rev. D 92, 105013 (2015) | 10.1103/PhysRevD.92.105013 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a privileged Fock quantization of a massive Dirac field in a
closed Friedmann-Robertson-Walker cosmology, partially selected by the criteria
of invariance of the vacuum under the symmetries of the field equations, and
unitary implementation of the dynamics. When quantizing free scalar fields in
homogeneous and isotropic spacetimes with compact spatial sections, these
criteria have been shown to pick out a unique Fock representation (up to
unitary equivalence). Here, we employ the same criteria for fermion fields and
explore whether that uniqueness result can be extended to the case of the Fock
quantization of fermions. For the massive Dirac field, we start by introducing
a specific choice of the complex structure that determines the Fock
representation. Such structure is invariant under the symmetries of the
equations of motion. We then prove that the corresponding representation of the
canonical anticommutation relations admits a unitary implementation of the
dynamics. Moreover, we construct a rather general class of representations that
satisfy the above criteria, and we demonstrate that they are all unitarily
equivalent to our previous choice. The complex structures in this class are
restricted only by certain conditions on their asymptotic behavior for modes in
the ultraviolet sector of the Dirac operator. We finally show that, if one
assumes that these asymptotic conditions are in fact trivial once our criteria
are fulfilled, then the time-dependent scaling in the definition of the
fermionic annihilation and creation-like variables is essentially unique.
| [
{
"created": "Wed, 30 Sep 2015 09:08:42 GMT",
"version": "v1"
}
] | 2015-11-11 | [
[
"Cortez",
"Jerónimo",
""
],
[
"Navascués",
"Beatriz Elizaga",
""
],
[
"Martín-Benito",
"Mercedes",
""
],
[
"Marugán",
"Guillermo A. Mena",
""
],
[
"Velhinho",
"José M.",
""
]
] | We present a privileged Fock quantization of a massive Dirac field in a closed Friedmann-Robertson-Walker cosmology, partially selected by the criteria of invariance of the vacuum under the symmetries of the field equations, and unitary implementation of the dynamics. When quantizing free scalar fields in homogeneous and isotropic spacetimes with compact spatial sections, these criteria have been shown to pick out a unique Fock representation (up to unitary equivalence). Here, we employ the same criteria for fermion fields and explore whether that uniqueness result can be extended to the case of the Fock quantization of fermions. For the massive Dirac field, we start by introducing a specific choice of the complex structure that determines the Fock representation. Such structure is invariant under the symmetries of the equations of motion. We then prove that the corresponding representation of the canonical anticommutation relations admits a unitary implementation of the dynamics. Moreover, we construct a rather general class of representations that satisfy the above criteria, and we demonstrate that they are all unitarily equivalent to our previous choice. The complex structures in this class are restricted only by certain conditions on their asymptotic behavior for modes in the ultraviolet sector of the Dirac operator. We finally show that, if one assumes that these asymptotic conditions are in fact trivial once our criteria are fulfilled, then the time-dependent scaling in the definition of the fermionic annihilation and creation-like variables is essentially unique. |
gr-qc/9612017 | Kristin Schleich | Donald Witt and Kristin Schleich | Toward a definition of chaos for general relativity | 5 pages. Amstex 2.1; also requires included fic.sty macro. Paper to
appear in Proceedings of the Sixth Canadian Conference on General Relativity
and Relativistic Astrophysics, The Fields Institute Communications Series | null | null | null | gr-qc | null | General relativity exhibits a unique feature not represented in standard
examples of chaotic systems; it is a spacetime diffeomorphism invariant theory.
Thus many characterizations of chaos do not work. It is therefore necessary to
develop a definition of chaos suitable for application to general relativity.
This presentation will present results towards this goal.
| [
{
"created": "Fri, 6 Dec 1996 18:46:09 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Witt",
"Donald",
""
],
[
"Schleich",
"Kristin",
""
]
] | General relativity exhibits a unique feature not represented in standard examples of chaotic systems; it is a spacetime diffeomorphism invariant theory. Thus many characterizations of chaos do not work. It is therefore necessary to develop a definition of chaos suitable for application to general relativity. This presentation will present results towards this goal. |
1205.0146 | Bibhas Majhi Ranjan | Bibhas Ranjan Majhi, Dibakar Roychowdhury | Phase transition and scaling behavior of topological charged black holes
in Horava-Lifshitz gravity | Minor corrections, refs. added, to appear in Class. Quant. Grav.
arXiv admin note: text overlap with arXiv:1111.0973 by other authors | Class. Quantum Grav. 29: 245012, 2012 | 10.1088/0264-9381/29/24/245012 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/3.0/ | Gravity can be thought as an emergent phenomenon and it has a nice
"thermodynamic" structure. In this context, it is then possible to study the
thermodynamics without knowing the details of the underlying microscopic
degrees of freedom. Here, based on the ordinary thermodynamics, we investigate
the phase transition of the static, spherically symmetric charged black hole
solution with arbitrary scalar curvature $2k$ in Ho\v{r}ava-Lifshitz gravity at
the Lifshitz point $z=3$. The analysis is done using the canonical ensemble
frame work; i.e. the charge is kept fixed. We find (a) for both $k=0$ and
$k=1$, there is no phase transition, (b) while $k=-1$ case exhibits the second
order phase transition within the {\it physical region} of the black hole. The
critical point of second order phase transition is obtained by the divergence
of the heat capacity at constant charge. Near the critical point, we find the
various critical exponents. It is also observed that they satisfy the usual
thermodynamic scaling laws.
| [
{
"created": "Tue, 1 May 2012 12:00:18 GMT",
"version": "v1"
},
{
"created": "Sun, 11 Nov 2012 10:30:48 GMT",
"version": "v2"
}
] | 2012-11-27 | [
[
"Majhi",
"Bibhas Ranjan",
""
],
[
"Roychowdhury",
"Dibakar",
""
]
] | Gravity can be thought as an emergent phenomenon and it has a nice "thermodynamic" structure. In this context, it is then possible to study the thermodynamics without knowing the details of the underlying microscopic degrees of freedom. Here, based on the ordinary thermodynamics, we investigate the phase transition of the static, spherically symmetric charged black hole solution with arbitrary scalar curvature $2k$ in Ho\v{r}ava-Lifshitz gravity at the Lifshitz point $z=3$. The analysis is done using the canonical ensemble frame work; i.e. the charge is kept fixed. We find (a) for both $k=0$ and $k=1$, there is no phase transition, (b) while $k=-1$ case exhibits the second order phase transition within the {\it physical region} of the black hole. The critical point of second order phase transition is obtained by the divergence of the heat capacity at constant charge. Near the critical point, we find the various critical exponents. It is also observed that they satisfy the usual thermodynamic scaling laws. |
2211.14507 | Yurii Ignat'ev | Yu.G. Ignat'ev | Single-Field Model of Gravitational-Scalar Instability. II. Black Hole
Formation | 8 pages, 9 figures, 10 references | Gravit. Cosmol. 28 (2022) 375-381 | 10.1134/S0202289322040107 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | On the basis of the previously formulated mathematical model of a statistical
system with scalar interaction of fermions and the theory of
gravitational-scalar instability of a cosmological model based on a
one-component statistical system of scalarly charged degenerate fermions (\MIO
models), the possibility of the formation of black holes in the early Universe
using the mechanism of gravitational-scalar instability, which ensures the
exponential growth of perturbations. The evolution of spherical masses in the
\MIO model, as well as the evolution of black holes with allowance for their
evaporation, is studied. The argumentation of the possibility of the formation
of black holes in the early Universe with the help of the proposed mechanism is
given, and a numerical model is constructed that confirms this argumentation.
The range of parameters of the \MIO model, which ensures the growth of black
hole masses in the early Universe up to $10^4\div10^6 M_\odot$, is identified.
| [
{
"created": "Sat, 26 Nov 2022 07:54:18 GMT",
"version": "v1"
}
] | 2022-11-29 | [
[
"Ignat'ev",
"Yu. G.",
""
]
] | On the basis of the previously formulated mathematical model of a statistical system with scalar interaction of fermions and the theory of gravitational-scalar instability of a cosmological model based on a one-component statistical system of scalarly charged degenerate fermions (\MIO models), the possibility of the formation of black holes in the early Universe using the mechanism of gravitational-scalar instability, which ensures the exponential growth of perturbations. The evolution of spherical masses in the \MIO model, as well as the evolution of black holes with allowance for their evaporation, is studied. The argumentation of the possibility of the formation of black holes in the early Universe with the help of the proposed mechanism is given, and a numerical model is constructed that confirms this argumentation. The range of parameters of the \MIO model, which ensures the growth of black hole masses in the early Universe up to $10^4\div10^6 M_\odot$, is identified. |
0904.0215 | Dawood Kothawala | Dawood Kothawala, T. Padmanabhan | Thermodynamic structure of Lanczos-Lovelock field equations from
near-horizon symmetries | RevTeX 4; 10 pages; no figures | Phys.Rev.D79:104020,2009 | 10.1103/PhysRevD.79.104020 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is well known that, for a wide class of spacetimes with horizons, Einstein
equations near the horizon can be written as a thermodynamic identity. It is
also known that the Einstein tensor acquires a highly symmetric form near
static, as well as stationary, horizons. We show that, for generic static
spacetimes, this highly symmetric form of the Einstein tensor leads quite
naturally and generically to the interpretation of the near-horizon field
equations as a thermodynamic identity. We further extend this result to generic
static spacetimes in Lanczos-Lovelock gravity, and show that the near-horizon
field equations again represent a thermodynamic identity in all these models.
These results confirm the conjecture that this thermodynamic perspective of
gravity extends far beyond Einstein's theory.
| [
{
"created": "Wed, 1 Apr 2009 16:46:18 GMT",
"version": "v1"
}
] | 2009-07-30 | [
[
"Kothawala",
"Dawood",
""
],
[
"Padmanabhan",
"T.",
""
]
] | It is well known that, for a wide class of spacetimes with horizons, Einstein equations near the horizon can be written as a thermodynamic identity. It is also known that the Einstein tensor acquires a highly symmetric form near static, as well as stationary, horizons. We show that, for generic static spacetimes, this highly symmetric form of the Einstein tensor leads quite naturally and generically to the interpretation of the near-horizon field equations as a thermodynamic identity. We further extend this result to generic static spacetimes in Lanczos-Lovelock gravity, and show that the near-horizon field equations again represent a thermodynamic identity in all these models. These results confirm the conjecture that this thermodynamic perspective of gravity extends far beyond Einstein's theory. |
gr-qc/0703093 | Christopher Eling | David Garfinkle, Christopher Eling, Ted Jacobson | Numerical simulations of gravitational collapse in Einstein-aether
theory | 9 pages, 7 figures; v2: corrected typos, added minor clarifying
remarks, improved discussion of results in conclusion | Phys.Rev.D76:024003,2007 | 10.1103/PhysRevD.76.024003 | null | gr-qc astro-ph hep-th | null | We study gravitational collapse of a spherically symmetric scalar field in
Einstein-aether theory (general relativity coupled to a dynamical unit timelike
vector field). The initial value formulation is developed, and numerical
simulations are performed. The collapse produces regular, stationary black
holes, as long as the aether coupling constants are not too large. For larger
couplings a finite area singularity occurs. These results are shown to be
consistent with the stationary solutions found previously.
| [
{
"created": "Sun, 18 Mar 2007 21:03:31 GMT",
"version": "v1"
},
{
"created": "Sun, 1 Jul 2007 18:45:07 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Garfinkle",
"David",
""
],
[
"Eling",
"Christopher",
""
],
[
"Jacobson",
"Ted",
""
]
] | We study gravitational collapse of a spherically symmetric scalar field in Einstein-aether theory (general relativity coupled to a dynamical unit timelike vector field). The initial value formulation is developed, and numerical simulations are performed. The collapse produces regular, stationary black holes, as long as the aether coupling constants are not too large. For larger couplings a finite area singularity occurs. These results are shown to be consistent with the stationary solutions found previously. |
1801.07906 | Mehrab Momennia | Seyed Hossein Hendi, Mehrab Momennia | Thermodynamic description and quasinormal modes of adS black holes in
Born-Infeld massive gravity with a non-abelian hair | 21 pages and 7 figures. Published version | JHEP 10 (2019) 207 | 10.1007/JHEP10(2019)207 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct a new class of asymptotically (a)dS black hole solutions of
Einstein-Yang-Mills massive gravity in the presence of Born-Infeld nonlinear
electrodynamics. The obtained solutions possess a Coulomb electric charge,
massive term and a non-abelian hair as well. We calculate the conserved and
thermodynamic quantities, and investigate the validity of the first law of
thermodynamics. Also, we investigate thermal stability conditions by using the
sign of heat capacity through canonical ensemble. Next, we consider the
cosmological constant as a thermodynamical pressure and study the van der Waals
like phase transition of black holes in the extended phase space
thermodynamics. Our results indicate the existence of a phase transition which
is affected by the parameters of theory. Finally, we consider a massless scalar
perturbation in the background of asymptotically adS solutions and calculate
the quasinormal modes by employing the pseudospectral method. The imaginary
part of quasinormal frequencies is the time scale of a thermal state (in the
conformal field theory) for the approach to thermal equilibrium.
| [
{
"created": "Wed, 24 Jan 2018 08:33:06 GMT",
"version": "v1"
},
{
"created": "Tue, 29 Jan 2019 09:15:02 GMT",
"version": "v2"
},
{
"created": "Thu, 24 Oct 2019 07:35:20 GMT",
"version": "v3"
}
] | 2022-08-09 | [
[
"Hendi",
"Seyed Hossein",
""
],
[
"Momennia",
"Mehrab",
""
]
] | We construct a new class of asymptotically (a)dS black hole solutions of Einstein-Yang-Mills massive gravity in the presence of Born-Infeld nonlinear electrodynamics. The obtained solutions possess a Coulomb electric charge, massive term and a non-abelian hair as well. We calculate the conserved and thermodynamic quantities, and investigate the validity of the first law of thermodynamics. Also, we investigate thermal stability conditions by using the sign of heat capacity through canonical ensemble. Next, we consider the cosmological constant as a thermodynamical pressure and study the van der Waals like phase transition of black holes in the extended phase space thermodynamics. Our results indicate the existence of a phase transition which is affected by the parameters of theory. Finally, we consider a massless scalar perturbation in the background of asymptotically adS solutions and calculate the quasinormal modes by employing the pseudospectral method. The imaginary part of quasinormal frequencies is the time scale of a thermal state (in the conformal field theory) for the approach to thermal equilibrium. |
2112.14133 | Guangzhou Guo | Guangzhou Guo, Peng Wang, Houwen Wu, and Haitang Yang | Quasinormal Modes of Black Holes with Multiple Photon Spheres | 25 pages, 4 figures, 1 table, references added | null | 10.1007/JHEP06(2022)060 | CTP-SCU/2021038 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | For a static and spherically symmetric black hole, a photon sphere is
composed of circular null geodesics of fixed radius, and plays an important
role in observing the black hole. Recently, in an Einstein-Maxwell-scalar model
with a non-minimal coupling between the scalar and electromagnetic fields, a
class of hairy black holes has been found to possess two unstable and one
stable circular null geodesics on the equatorial plane, corresponding to three
photon spheres outside the event horizon. In this paper, we study quasinormal
modes of the scalar field, which are associated with these circular null
geodesics, in the hairy black hole spacetime. In the eikonal regime with
$l\gg1$, the real part of the quasinormal modes is determined by the angular
velocity of the corresponding circular geodesics. The imaginary part of the
quasinormal modes associated with the unstable circular null geodesics encodes
the information about the Lyapunov exponent of the corresponding circular
geodesics. Interestingly, we find long-lived and sub-long-lived modes, which
are associated with the stable and one of the unstable circular null geodesics,
respectively. Due to tunneling through potential barriers, the damping times of
the long-lived and sub-long-lived modes can be exponentially and
logarithmically large in terms of $l$, respectively.
| [
{
"created": "Tue, 28 Dec 2021 13:22:20 GMT",
"version": "v1"
},
{
"created": "Thu, 6 Jan 2022 11:21:00 GMT",
"version": "v2"
}
] | 2022-06-29 | [
[
"Guo",
"Guangzhou",
""
],
[
"Wang",
"Peng",
""
],
[
"Wu",
"Houwen",
""
],
[
"Yang",
"Haitang",
""
]
] | For a static and spherically symmetric black hole, a photon sphere is composed of circular null geodesics of fixed radius, and plays an important role in observing the black hole. Recently, in an Einstein-Maxwell-scalar model with a non-minimal coupling between the scalar and electromagnetic fields, a class of hairy black holes has been found to possess two unstable and one stable circular null geodesics on the equatorial plane, corresponding to three photon spheres outside the event horizon. In this paper, we study quasinormal modes of the scalar field, which are associated with these circular null geodesics, in the hairy black hole spacetime. In the eikonal regime with $l\gg1$, the real part of the quasinormal modes is determined by the angular velocity of the corresponding circular geodesics. The imaginary part of the quasinormal modes associated with the unstable circular null geodesics encodes the information about the Lyapunov exponent of the corresponding circular geodesics. Interestingly, we find long-lived and sub-long-lived modes, which are associated with the stable and one of the unstable circular null geodesics, respectively. Due to tunneling through potential barriers, the damping times of the long-lived and sub-long-lived modes can be exponentially and logarithmically large in terms of $l$, respectively. |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.