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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0811.1008 | Savely G. Karshenboim | Savely G. Karshenboim (Max-Planck-Institut fuer Quantenoptik, Garching
and D.I. Mendeleev Institute for Metrology, St.Petersburg) | A constraint on antigravity of antimatter from precision spectroscopy of
simple atoms | null | null | 10.1134/S1063773709100028 | null | gr-qc physics.atom-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Consideration of antigravity for antiparticles is an attractive target for
various experimental projects. There are a number of theoretical arguments
against it but it is not quite clear what kind of experimental data and
theoretical suggestions are involved. In this paper we present straightforward
arguments against a possibility of antigravity based on a few simple
theoretical suggestions and some experimental data. The data are: astrophysical
data on rotation of the Solar System in respect to the center of our galaxy and
precision spectroscopy data on hydrogen and positronium. The theoretical
suggestions for the case of absence of the gravitational field are: equality of
electron and positron mass and equality of proton and positron charge. We also
assume that QED is correct at the level of accuracy where it is clearly
confirmed experimentally.
| [
{
"created": "Thu, 6 Nov 2008 18:13:57 GMT",
"version": "v1"
}
] | 2014-11-04 | [
[
"Karshenboim",
"Savely G.",
"",
"Max-Planck-Institut fuer Quantenoptik, Garching\n and D.I. Mendeleev Institute for Metrology, St.Petersburg"
]
] | Consideration of antigravity for antiparticles is an attractive target for various experimental projects. There are a number of theoretical arguments against it but it is not quite clear what kind of experimental data and theoretical suggestions are involved. In this paper we present straightforward arguments against a possibility of antigravity based on a few simple theoretical suggestions and some experimental data. The data are: astrophysical data on rotation of the Solar System in respect to the center of our galaxy and precision spectroscopy data on hydrogen and positronium. The theoretical suggestions for the case of absence of the gravitational field are: equality of electron and positron mass and equality of proton and positron charge. We also assume that QED is correct at the level of accuracy where it is clearly confirmed experimentally. |
1811.04743 | Sylvestre Lacour | S Lacour, F H Vincent, M Nowak, A Le Tiec, V Lapeyrere, L David, P
Bourget, A Kellerer, K Jani, J Martino, J-Y Vinet, O Godet O Straub and J
Woillez | SAGE: finding IMBH in the black hole desert | Accepted in Class. Quantum Grav | null | 10.1088/1361-6382/ab3583 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | SAGE (SagnAc interferometer for Gravitational wavE) is a project for a space
observatory based on multiple 12-U CubeSats in geosynchronous orbit. The
objective is a fast track mission which would fill the observational gap
between LISA and ground based observatories. With albeit a lower sensitivity,
it would allow early investigation of the nature and event rate of
intermediate-mass black hole (IMBH) mergers, constraining our understanding of
the universe formation by probing the building up of IMBH up to supermassive
black holes. Technically, the CubeSats would create a triangular Sagnac
interferometer with 140.000km roundtrip arm length, optimized to be sensitive
to gravitational waves at frequencies between 10mHz and 2Hz. The nature of the
Sagnac measurement makes it almost insensitive to position error, enabling the
use of spacecrafts in ballistic trajectories. The light source and
recombination units of the interferometer are based on compact fibered
technologies without bulk optics. A peak sensitivity of 23 pm/sqrt(Hz) is
expected at 1Hz assuming a 200mW internal laser source and 10-centimeter
diameter apertures. Because of the absence of a test mass, the main limitation
would come from the non-gravitational forces applied on the spacecrafts.
However, conditionally upon our ability to partially post-process the effect of
solar wind and solar pressure, SAGE would allow detection of gravitational
waves with strains as low as a few 1e-19 within the 0.1 to 1Hz range. Averaged
over the entire sky, and including the antenna gain of the Sagnac
interferometer, the SAGE observatory would sense equal mass black hole mergers
in the 1e4 to 1e6 solar masses range up to a luminosity distance of 800Mpc.
Additionally, coalescence of stellar black holes (10Msun) around SMBH (IMBH)
forming extreme (intermediate) mass ratio inspirals could be detected within a
sphere of radius 200Mpc.
| [
{
"created": "Mon, 12 Nov 2018 14:36:38 GMT",
"version": "v1"
},
{
"created": "Thu, 8 Aug 2019 09:45:47 GMT",
"version": "v2"
}
] | 2020-01-08 | [
[
"Lacour",
"S",
""
],
[
"Vincent",
"F H",
""
],
[
"Nowak",
"M",
""
],
[
"Tiec",
"A Le",
""
],
[
"Lapeyrere",
"V",
""
],
[
"David",
"L",
""
],
[
"Bourget",
"P",
""
],
[
"Kellerer",
"A",
""
]... | SAGE (SagnAc interferometer for Gravitational wavE) is a project for a space observatory based on multiple 12-U CubeSats in geosynchronous orbit. The objective is a fast track mission which would fill the observational gap between LISA and ground based observatories. With albeit a lower sensitivity, it would allow early investigation of the nature and event rate of intermediate-mass black hole (IMBH) mergers, constraining our understanding of the universe formation by probing the building up of IMBH up to supermassive black holes. Technically, the CubeSats would create a triangular Sagnac interferometer with 140.000km roundtrip arm length, optimized to be sensitive to gravitational waves at frequencies between 10mHz and 2Hz. The nature of the Sagnac measurement makes it almost insensitive to position error, enabling the use of spacecrafts in ballistic trajectories. The light source and recombination units of the interferometer are based on compact fibered technologies without bulk optics. A peak sensitivity of 23 pm/sqrt(Hz) is expected at 1Hz assuming a 200mW internal laser source and 10-centimeter diameter apertures. Because of the absence of a test mass, the main limitation would come from the non-gravitational forces applied on the spacecrafts. However, conditionally upon our ability to partially post-process the effect of solar wind and solar pressure, SAGE would allow detection of gravitational waves with strains as low as a few 1e-19 within the 0.1 to 1Hz range. Averaged over the entire sky, and including the antenna gain of the Sagnac interferometer, the SAGE observatory would sense equal mass black hole mergers in the 1e4 to 1e6 solar masses range up to a luminosity distance of 800Mpc. Additionally, coalescence of stellar black holes (10Msun) around SMBH (IMBH) forming extreme (intermediate) mass ratio inspirals could be detected within a sphere of radius 200Mpc. |
1808.00952 | Simone Speziale | Simone Speziale | Raychaudhuri and optical equations for null geodesic congruences with
torsion | v2: improved text, a few equations and a subsection added. v3: typo
in one equation corrected, improved conclusions and other minor amendments | Phys. Rev. D 98, 084029 (2018) | 10.1103/PhysRevD.98.084029 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study null geodesic congruences (NGCs) in the presence of spacetime
torsion, recovering and extending results in the literature. Only the highest
spin irreducible component of torsion gives a proper acceleration with respect
to metric NGCs, but at the same time obstructs abreastness of the geodesics.
This means that it is necessary to follow the evolution of the drift term in
the optical equations, and not just shear, twist and expansion. We show how the
optical equations depend on the non-Riemannian components of the curvature, and
how they reduce to the metric ones when the highest spin component of torsion
vanishes.
| [
{
"created": "Thu, 2 Aug 2018 17:56:57 GMT",
"version": "v1"
},
{
"created": "Mon, 10 Sep 2018 17:19:13 GMT",
"version": "v2"
},
{
"created": "Tue, 16 Oct 2018 16:56:05 GMT",
"version": "v3"
}
] | 2018-10-24 | [
[
"Speziale",
"Simone",
""
]
] | We study null geodesic congruences (NGCs) in the presence of spacetime torsion, recovering and extending results in the literature. Only the highest spin irreducible component of torsion gives a proper acceleration with respect to metric NGCs, but at the same time obstructs abreastness of the geodesics. This means that it is necessary to follow the evolution of the drift term in the optical equations, and not just shear, twist and expansion. We show how the optical equations depend on the non-Riemannian components of the curvature, and how they reduce to the metric ones when the highest spin component of torsion vanishes. |
0708.3999 | Ernst Nils Dorband | Luciano Rezzolla, Ernst Nils Dorband, Christian Reisswig, Peter
Diener, Denis Pollney, Erik Schnetter and Bela Szilagyi | Spin Diagrams for Equal-Mass Black-Hole Binaries with Aligned Spins | 4 pages, 3 figs; small changes matching published version | Astrophys.J. 679:1422-1426,2008 | 10.1086/587679 | null | gr-qc astro-ph | null | Binary black-hole systems with spins aligned with the orbital angular
momentum are of special interest as they may be the preferred end-state of the
inspiral of generic supermassive binary black-hole systems. In view of this, we
have computed the inspiral and merger of a large set of binary systems of
equal-mass black holes with spins aligned with the orbital angular momentum but
otherwise arbitrary. By least-square fitting the results of these simulations
we have constructed two "spin diagrams" which provide straightforward
information about the recoil velocity |v_kick| and the final black-hole spin
a_fin in terms of the dimensionless spins a_1 and a_2 of the two initial black
holes. Overall they suggest a maximum recoil velocity of |v_kick|=441.94 km/s,
and minimum and maximum final spins a_fin=0.3471 and a_fin=0.9591,
respectively.
| [
{
"created": "Wed, 29 Aug 2007 17:33:55 GMT",
"version": "v1"
},
{
"created": "Sat, 23 Feb 2008 17:53:07 GMT",
"version": "v2"
}
] | 2011-02-18 | [
[
"Rezzolla",
"Luciano",
""
],
[
"Dorband",
"Ernst Nils",
""
],
[
"Reisswig",
"Christian",
""
],
[
"Diener",
"Peter",
""
],
[
"Pollney",
"Denis",
""
],
[
"Schnetter",
"Erik",
""
],
[
"Szilagyi",
"Bela",
""
... | Binary black-hole systems with spins aligned with the orbital angular momentum are of special interest as they may be the preferred end-state of the inspiral of generic supermassive binary black-hole systems. In view of this, we have computed the inspiral and merger of a large set of binary systems of equal-mass black holes with spins aligned with the orbital angular momentum but otherwise arbitrary. By least-square fitting the results of these simulations we have constructed two "spin diagrams" which provide straightforward information about the recoil velocity |v_kick| and the final black-hole spin a_fin in terms of the dimensionless spins a_1 and a_2 of the two initial black holes. Overall they suggest a maximum recoil velocity of |v_kick|=441.94 km/s, and minimum and maximum final spins a_fin=0.3471 and a_fin=0.9591, respectively. |
1712.02978 | Nikolaos Kalogeropoulos | Nikolaos Kalogeropoulos | Embolic aspects of black hole entropy | 11 pages. No figures. LaTeX2e. Final form, to be published in the
Int. J. Geom. Methods Mod. Physics | Int. J. Geom. Methods Mod. Phys. 15, 1850175 (2018) | 10.1142/S021988781850175X | null | gr-qc cond-mat.stat-mech hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We attempt to provide a mesoscopic treatment of the origin of black hole
entropy in (3+1)-dimensional spacetimes. We treat the case of horizons having
space-like sections $\Sigma$ which are topological spheres, following Hawking's
and the Topological Censorship theorems. We use the injectivity radius of the
induced metric on $\Sigma$ to encode the linear dimensions of the elementary
cells giving rise to such entropy. We use the topological entropy of $\Sigma$
as the fundamental quantity expressing the complexity of $\Sigma$ on which its
entropy depends. We point out the significance, in this context, of the Berger
and Croke isoembolic inequalities.
| [
{
"created": "Fri, 8 Dec 2017 08:33:26 GMT",
"version": "v1"
},
{
"created": "Thu, 14 Jun 2018 12:24:43 GMT",
"version": "v2"
},
{
"created": "Thu, 5 Jul 2018 08:07:35 GMT",
"version": "v3"
}
] | 2018-11-14 | [
[
"Kalogeropoulos",
"Nikolaos",
""
]
] | We attempt to provide a mesoscopic treatment of the origin of black hole entropy in (3+1)-dimensional spacetimes. We treat the case of horizons having space-like sections $\Sigma$ which are topological spheres, following Hawking's and the Topological Censorship theorems. We use the injectivity radius of the induced metric on $\Sigma$ to encode the linear dimensions of the elementary cells giving rise to such entropy. We use the topological entropy of $\Sigma$ as the fundamental quantity expressing the complexity of $\Sigma$ on which its entropy depends. We point out the significance, in this context, of the Berger and Croke isoembolic inequalities. |
gr-qc/0702121 | Branislav Cvetkovi\'c | B. Cvetkovic and M. Blagojevic | Supersymmetric 3D gravity with torsion: asymptotic symmetries | LATEX, 21 pages, v2: minor corrections, improvements in the
presentation; v3: slightly improved form of the asymptotic supersymmetry
algebra | Class.Quant.Grav.24:3933-3950,2007 | 10.1088/0264-9381/24/15/011 | null | gr-qc hep-th | null | We study the structure of asymptotic symmetries in N=1+1 supersymmetric
extension of three-dimensional gravity with torsion. Using a natural
generalization of the bosonic anti-de Sitter asymptotic conditions, we show
that the asymptotic Poisson bracket algebra of the canonical generators has the
form of two independent super-Virasoro algebras with different central charges.
| [
{
"created": "Fri, 23 Feb 2007 11:22:34 GMT",
"version": "v1"
},
{
"created": "Mon, 5 Mar 2007 09:53:10 GMT",
"version": "v2"
},
{
"created": "Fri, 6 Jul 2007 08:19:01 GMT",
"version": "v3"
}
] | 2008-11-26 | [
[
"Cvetkovic",
"B.",
""
],
[
"Blagojevic",
"M.",
""
]
] | We study the structure of asymptotic symmetries in N=1+1 supersymmetric extension of three-dimensional gravity with torsion. Using a natural generalization of the bosonic anti-de Sitter asymptotic conditions, we show that the asymptotic Poisson bracket algebra of the canonical generators has the form of two independent super-Virasoro algebras with different central charges. |
0901.1561 | Marcello Ortaggio | Marcello Ortaggio, Vojtech Pravda, Alena Pravdova | On Kerr-Schild spacetimes in higher dimensions | 5 pages. Proceedings of the Spanish Relativity Meeting 2008,
Salamanca, September 15-19, 2008 (http://www.usal.es/ere2008/) | AIP Conf.Proc.1122:364-367,2009 | 10.1063/1.3141327 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We summarize main properties of vacuum Kerr-Schild spacetimes in higher
dimensions.
| [
{
"created": "Mon, 12 Jan 2009 13:16:09 GMT",
"version": "v1"
}
] | 2009-12-04 | [
[
"Ortaggio",
"Marcello",
""
],
[
"Pravda",
"Vojtech",
""
],
[
"Pravdova",
"Alena",
""
]
] | We summarize main properties of vacuum Kerr-Schild spacetimes in higher dimensions. |
gr-qc/9901077 | Grigori Volovik | G.E. Volovik | Simulation of Panleve-Gullstrand black hole in thin 3He-A film | 8 pages, 4 figures, extended version submitted to JETP Lett | Pisma Zh.Eksp.Teor.Fiz. 69 (1999) 662-668; JETP Lett. 69 (1999)
705-713 | 10.1134/1.568079 | null | gr-qc cond-mat hep-ph | null | The quasi-stationary superfluid state is constructed, which exhibits the
event horizon and Hawking radiation.
| [
{
"created": "Wed, 27 Jan 1999 09:40:16 GMT",
"version": "v1"
},
{
"created": "Wed, 31 Mar 1999 11:10:33 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Volovik",
"G. E.",
""
]
] | The quasi-stationary superfluid state is constructed, which exhibits the event horizon and Hawking radiation. |
0706.0375 | Sumati Surya | Graham Brightwell, Joe Henson, Sumati Surya | A 2D model of Causal Set Quantum Gravity: The emergence of the continuum | Corrections and clarifications. Conclusions unchanged | Class.Quant.Grav.25:105025,2008 | 10.1088/0264-9381/25/10/105025 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Non-perturbative theories of quantum gravity inevitably include
configurations that fail to resemble physically reasonable spacetimes at large
scales. Often, these configurations are entropically dominant and pose an
obstacle to obtaining the desired classical limit. We examine this "entropy
problem" in a model of causal set quantum gravity corresponding to a
discretisation of 2D spacetimes. Using results from the theory of partial
orders we show that, in the large volume or continuum limit, its partition
function is dominated by causal sets which approximate to a region of 2D
Minkowski space. This model of causal set quantum gravity thus overcomes the
entropy problem and predicts the emergence of a physically reasonable geometry.
| [
{
"created": "Mon, 4 Jun 2007 05:14:34 GMT",
"version": "v1"
},
{
"created": "Mon, 26 Nov 2007 06:47:55 GMT",
"version": "v2"
},
{
"created": "Wed, 17 Sep 2008 09:33:22 GMT",
"version": "v3"
}
] | 2008-11-26 | [
[
"Brightwell",
"Graham",
""
],
[
"Henson",
"Joe",
""
],
[
"Surya",
"Sumati",
""
]
] | Non-perturbative theories of quantum gravity inevitably include configurations that fail to resemble physically reasonable spacetimes at large scales. Often, these configurations are entropically dominant and pose an obstacle to obtaining the desired classical limit. We examine this "entropy problem" in a model of causal set quantum gravity corresponding to a discretisation of 2D spacetimes. Using results from the theory of partial orders we show that, in the large volume or continuum limit, its partition function is dominated by causal sets which approximate to a region of 2D Minkowski space. This model of causal set quantum gravity thus overcomes the entropy problem and predicts the emergence of a physically reasonable geometry. |
2302.06545 | Roberto Maluf | F. M. Belchior, A. R. P. Moreira, R. V. Maluf and C. A. S. Almeida | 5D Elko spinor field non-minimally coupled to nonmetricity in $f(Q)$
gravity | 18 pages, 5 figures, matches published version in PLB | Phys. Lett. B, (2023), 138029 | 10.1016/j.physletb.2023.138029 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | This paper aims to investigate the localization of the five-dimensional
spinor field known as Elko (dual-helicity eigenspinors of the charge
conjugation operator) by employing a Yukawa-like geometrical coupling in which
the Elko field is non-minimally coupled to nonmetricity scalar $Q$. We adopt
the braneworld scenarios in which the first-order formalism with sine-Gordon
and linear superpotentials is employed to obtain the warp factors. A linear
function supports the zero-mode trapping within the geometric coupling, leading
to the same effective potential as the scalar field. Moreover, an exotic term
must be added to obtain real-valued massive modes. Such modes are investigated
through the Schr\"{o}dinger-like approach.
| [
{
"created": "Mon, 13 Feb 2023 17:36:55 GMT",
"version": "v1"
},
{
"created": "Sun, 18 Jun 2023 07:19:34 GMT",
"version": "v2"
}
] | 2023-06-21 | [
[
"Belchior",
"F. M.",
""
],
[
"Moreira",
"A. R. P.",
""
],
[
"Maluf",
"R. V.",
""
],
[
"Almeida",
"C. A. S.",
""
]
] | This paper aims to investigate the localization of the five-dimensional spinor field known as Elko (dual-helicity eigenspinors of the charge conjugation operator) by employing a Yukawa-like geometrical coupling in which the Elko field is non-minimally coupled to nonmetricity scalar $Q$. We adopt the braneworld scenarios in which the first-order formalism with sine-Gordon and linear superpotentials is employed to obtain the warp factors. A linear function supports the zero-mode trapping within the geometric coupling, leading to the same effective potential as the scalar field. Moreover, an exotic term must be added to obtain real-valued massive modes. Such modes are investigated through the Schr\"{o}dinger-like approach. |
1611.02611 | Carlos Ernesto Laciana | Carlos E. Laciana | A causal viscous cosmology without singularities | 16 pages | Gen Relativ Gravit (2017) 49; 62 | 10.1007/s10714-017-2215-x | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An isotropic and homogeneous cosmological model with a source of dark energy
is studied. That source is simulated with a viscous relativistic fluid with
minimal causal correction. In this model the restrictions on the parameters
coming from the following conditions are analized: a) energy density without
singularities along time, b) scale factor increasing with time, c) universe
accelerated at present time, d) state equation for dark energy with "w" bounded
and close to -1. It is found that those conditions are satified for the
following two cases. i) When the transport coefficient ({\tau}_{{\Pi}}),
associated to the causal correction, is negative, with the aditional
restriction {\zeta}|{\tau}_{{\Pi}}|>2/3, where {\zeta} is the relativistic bulk
viscosity coefficient. The state equation is in the "phantom" energy sector.
ii) For {\tau}_{{\Pi}} positive, in the "k-essence" sector. It is performed an
exact calculation for the case where the equation of state is constant, finding
that option (ii) is favored in relation to (i), because in (ii) the entropy is
always increasing, while this does no happen in (i).
| [
{
"created": "Tue, 8 Nov 2016 17:12:01 GMT",
"version": "v1"
},
{
"created": "Wed, 1 Mar 2017 17:41:14 GMT",
"version": "v2"
},
{
"created": "Wed, 19 Apr 2017 17:20:16 GMT",
"version": "v3"
}
] | 2017-04-20 | [
[
"Laciana",
"Carlos E.",
""
]
] | An isotropic and homogeneous cosmological model with a source of dark energy is studied. That source is simulated with a viscous relativistic fluid with minimal causal correction. In this model the restrictions on the parameters coming from the following conditions are analized: a) energy density without singularities along time, b) scale factor increasing with time, c) universe accelerated at present time, d) state equation for dark energy with "w" bounded and close to -1. It is found that those conditions are satified for the following two cases. i) When the transport coefficient ({\tau}_{{\Pi}}), associated to the causal correction, is negative, with the aditional restriction {\zeta}|{\tau}_{{\Pi}}|>2/3, where {\zeta} is the relativistic bulk viscosity coefficient. The state equation is in the "phantom" energy sector. ii) For {\tau}_{{\Pi}} positive, in the "k-essence" sector. It is performed an exact calculation for the case where the equation of state is constant, finding that option (ii) is favored in relation to (i), because in (ii) the entropy is always increasing, while this does no happen in (i). |
gr-qc/0105110 | Giovanni Losurdo | G.Losurdo, G.Calamai, E.Cuoco, L.Fabbroni, G.Guidi, M.Mazzoni,
R.Stanga, F.Vetrano, L.Holloway, D.Passuello, G.Ballardin, S.Braccini,
C.Bradaschia, R.Cavalieri, R.Cecchi, G.Cella, V.Dattilo, A.Di Virgilio,
F.Fidecaro, F.Frasconi, A.Gennai, A.Giazotto, I.Ferrante, P.La Penna,
F.Lelli, T.Lomtadze, A.Marin, S.Mancini, F.Paoletti, A.Pasqualetti,
R.Passaquieti, R.Poggiani, R.Taddei, A.Vicere', Z.Zhang | Inertial control of the mirror suspensions of the VIRGO interferometer
for gravitational wave detection | 17 pages, 11 figures, accepted for publication on Review of
Scientific Instruments | Rev.Sci.Instrum. 72 (2001) 3653-3661 | 10.1063/1.1394189 | null | gr-qc | null | In order to achieve full detection sensitivity at low frequencies, the
mirrors of interferometric gravitational wave detectors must be isolated from
seismic noise. The VIRGO vibration isolator, called 'superattenuator', is fully
effective at frequencies above 4 Hz. Nevertheless, the residual motion of the
mirror at the mechanical resonant frequencies of the system are too large for
the interferometer locking system and must be damped. A multidimensional
feedback system, using inertial sensors and digital processing, has been
designed for this purpose. An experimental procedure for determining the
feedback control of the system has been defined. In this paper a full
description of the system is given and experimental results are presented.
| [
{
"created": "Mon, 28 May 2001 16:30:35 GMT",
"version": "v1"
},
{
"created": "Thu, 28 Jun 2001 10:26:01 GMT",
"version": "v2"
}
] | 2009-11-07 | [
[
"Losurdo",
"G.",
""
],
[
"Calamai",
"G.",
""
],
[
"Cuoco",
"E.",
""
],
[
"Fabbroni",
"L.",
""
],
[
"Guidi",
"G.",
""
],
[
"Mazzoni",
"M.",
""
],
[
"Stanga",
"R.",
""
],
[
"Vetrano",
"F.",
""... | In order to achieve full detection sensitivity at low frequencies, the mirrors of interferometric gravitational wave detectors must be isolated from seismic noise. The VIRGO vibration isolator, called 'superattenuator', is fully effective at frequencies above 4 Hz. Nevertheless, the residual motion of the mirror at the mechanical resonant frequencies of the system are too large for the interferometer locking system and must be damped. A multidimensional feedback system, using inertial sensors and digital processing, has been designed for this purpose. An experimental procedure for determining the feedback control of the system has been defined. In this paper a full description of the system is given and experimental results are presented. |
1905.08405 | Lijing Shao | Lijing Shao | Pulsar tests of the gravitational Lorentz violation | 4 pages; Presented at the Eighth Meeting on CPT and Lorentz Symmetry,
Bloomington, Indiana, May 12-16, 2019 | Proceedings of the Eighth Meeting on CPT and Lorentz Symmetry
(World Scientific, Singapore, 2020), p. 170 | 10.1142/9789811213984_0043 | null | gr-qc astro-ph.HE hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Pulsars are precision celestial clocks. When being put in a binary, the
ticking conveys the secret of underlying spacetime geometrodynamics. We use
pulsars to test if the gravitational interaction possesses a tiny deviation
from Einstein's General Relativity (GR). In the framework of Standard-Model
Extension (SME), we systematically search for Lorentz-violating operators
cataloged by (a) the minimal couplings of mass dimension 4, (b) the CPT
symmetry of mass dimension 5, and (c) the gravitational weak equivalence
principle (GWEP) of mass dimension 8. No deviation from GR was found yet.
| [
{
"created": "Tue, 21 May 2019 02:05:36 GMT",
"version": "v1"
}
] | 2020-05-01 | [
[
"Shao",
"Lijing",
""
]
] | Pulsars are precision celestial clocks. When being put in a binary, the ticking conveys the secret of underlying spacetime geometrodynamics. We use pulsars to test if the gravitational interaction possesses a tiny deviation from Einstein's General Relativity (GR). In the framework of Standard-Model Extension (SME), we systematically search for Lorentz-violating operators cataloged by (a) the minimal couplings of mass dimension 4, (b) the CPT symmetry of mass dimension 5, and (c) the gravitational weak equivalence principle (GWEP) of mass dimension 8. No deviation from GR was found yet. |
2308.11885 | Justin Feng | Justin C. Feng | Smooth metrics can hide thin shells | 2 pages, fixed typo | 2023 Class. Quantum Grav. 40 197002 | 10.1088/1361-6382/acf2de | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this note, I consider a class of metric tensors with smooth components
that naively appear to describe dynamical wormholes with vanishing spacetime
curvature. I point out that the smoothness of the metric tensor components is
deceptive, and that in general relativity, such metrics must be sourced by
exotic thin shells.
| [
{
"created": "Wed, 23 Aug 2023 03:04:38 GMT",
"version": "v1"
},
{
"created": "Sat, 2 Sep 2023 12:02:13 GMT",
"version": "v2"
}
] | 2023-09-07 | [
[
"Feng",
"Justin C.",
""
]
] | In this note, I consider a class of metric tensors with smooth components that naively appear to describe dynamical wormholes with vanishing spacetime curvature. I point out that the smoothness of the metric tensor components is deceptive, and that in general relativity, such metrics must be sourced by exotic thin shells. |
2301.06999 | Kwinten Fransen | Kwinten Fransen | Quasinormal Modes from Penrose Limits | 27 pages, 9 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We use Penrose limits to approximate quasinormal modes with large real
frequencies. The Penrose limit associates a plane wave to a region of spacetime
near a null geodesic. This plane wave can be argued to geometrically realize
the geometrical optics approximation. Therefore, when applied to the bound null
orbits around black holes, the Penrose limit can be used to study quasinormal
modes. For instance, this Penrose limit point of view makes manifest the
symmetry that emerges in the geometrical optics approximation of quasinormal
modes in terms of isometries of the resulting plane wave spacetime. We apply
the procedure to warped $\rm{AdS}_3$, Schwarzschild black holes and Kerr black
holes. In the former we show explicitly how the symmetry algebra contracts to
that of the limiting plane wave while in the latter we find the expected
agreement with numerically computed quasinormal modes for large (real)
frequencies.
| [
{
"created": "Tue, 17 Jan 2023 16:42:25 GMT",
"version": "v1"
}
] | 2023-01-18 | [
[
"Fransen",
"Kwinten",
""
]
] | We use Penrose limits to approximate quasinormal modes with large real frequencies. The Penrose limit associates a plane wave to a region of spacetime near a null geodesic. This plane wave can be argued to geometrically realize the geometrical optics approximation. Therefore, when applied to the bound null orbits around black holes, the Penrose limit can be used to study quasinormal modes. For instance, this Penrose limit point of view makes manifest the symmetry that emerges in the geometrical optics approximation of quasinormal modes in terms of isometries of the resulting plane wave spacetime. We apply the procedure to warped $\rm{AdS}_3$, Schwarzschild black holes and Kerr black holes. In the former we show explicitly how the symmetry algebra contracts to that of the limiting plane wave while in the latter we find the expected agreement with numerically computed quasinormal modes for large (real) frequencies. |
gr-qc/0505080 | Sean A. Hayward | Sean A. Hayward | Gravitational radiation from dynamical black holes | 5 revtex4 pages. Additional comments | Class.Quant.Grav. 23 (2006) L15 | 10.1088/0264-9381/23/3/L01 | null | gr-qc | null | An effective energy tensor for gravitational radiation is identified for
uniformly expanding flows of the Hawking mass-energy. It appears in an energy
conservation law expressing the change in mass due to the energy densities of
matter and gravitational radiation, with respect to a Killing-like vector
encoding a preferred flow of time outside a black hole. In a spin-coefficient
formulation, the components of the effective energy tensor can be understood as
the energy densities of ingoing and outgoing, transverse and longitudinal
gravitational radiation. By anchoring the flow to the trapping horizon of a
black hole in a given sequence of spatial hypersurfaces, there is a locally
unique flow and a measure of gravitational radiation in the strong-field
regime.
| [
{
"created": "Mon, 16 May 2005 17:18:26 GMT",
"version": "v1"
},
{
"created": "Mon, 26 Dec 2005 21:26:35 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Hayward",
"Sean A.",
""
]
] | An effective energy tensor for gravitational radiation is identified for uniformly expanding flows of the Hawking mass-energy. It appears in an energy conservation law expressing the change in mass due to the energy densities of matter and gravitational radiation, with respect to a Killing-like vector encoding a preferred flow of time outside a black hole. In a spin-coefficient formulation, the components of the effective energy tensor can be understood as the energy densities of ingoing and outgoing, transverse and longitudinal gravitational radiation. By anchoring the flow to the trapping horizon of a black hole in a given sequence of spatial hypersurfaces, there is a locally unique flow and a measure of gravitational radiation in the strong-field regime. |
2003.00477 | Tao Zhu | Cheng Liu, Tao Zhu, Qiang Wu, Kimet Jusufi, Mubasher Jamil, Mustapha
Azreg-A\"inou, and Anzhong Wang | Shadow and Quasinormal Modes of a Rotating Loop Quantum Black Hole | 21 pages, 12 figures; v2: several references added and version
published in Phys. Rev. D; some mistakes are corrected | Phys. Rev. D 101, 084001 (2020); Phys.Rev.D 103 (2021) 8, 089902
(erratum) | 10.1103/PhysRevD.101.084001 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we construct an effective rotating loop quantum black hole
(LQBH) solution, starting from the spherical symmetric LQBH by applying the
Newman-Janis algorithm modified by Azreg-A\"{i}nou's non-complexification
procedure, and study the effects of loop quantum gravity { (LQG) on its
shadow}. Given the rotating {LQBH}, we discuss its horizon, ergosurface, and
regularity {as} $r \to 0$. Depending on the values of the specific angular
momentum $a$ and the polymeric function $P$ arising from {LQG}, we {find} that
the rotating solution we obtained can represent a regular black hole, a regular
extreme black hole, or a regular spacetime {without horizon (a non-black-hole
solution)}. We also {study} the effects of {LQG} and rotation, and {show} that,
in addition to the specific angular momentum, the polymeric function {also}
causes deformations in the size and shape of the black hole shadow.
Interestingly, for a given value of $a$ and inclination angle $\theta_0$, the
apparent size of the shadow monotonically decreases, and the shadow gets more
distorted with increasing $P$. We also {consider the effects of $P$ on the
deviations from the circularity of the shadow, and find} that the deviation
from circularity increases with increasing $P$ for fixed values of $a$ and
$\theta_0$. Additionally, we explore the observational implications of $P$ in
comparison with the latest Event Horizon Telescope (EHT) observation of the
supermassive black hole, M$87$. The connection between the shadow radius and
quasinormal modes in the eikonal limit as well as {the} deflection of massive
particles are also considered.
| [
{
"created": "Sun, 1 Mar 2020 12:27:37 GMT",
"version": "v1"
},
{
"created": "Thu, 2 Apr 2020 03:07:34 GMT",
"version": "v2"
},
{
"created": "Mon, 10 May 2021 13:29:02 GMT",
"version": "v3"
}
] | 2021-05-11 | [
[
"Liu",
"Cheng",
""
],
[
"Zhu",
"Tao",
""
],
[
"Wu",
"Qiang",
""
],
[
"Jusufi",
"Kimet",
""
],
[
"Jamil",
"Mubasher",
""
],
[
"Azreg-Aïnou",
"Mustapha",
""
],
[
"Wang",
"Anzhong",
""
]
] | In this paper, we construct an effective rotating loop quantum black hole (LQBH) solution, starting from the spherical symmetric LQBH by applying the Newman-Janis algorithm modified by Azreg-A\"{i}nou's non-complexification procedure, and study the effects of loop quantum gravity { (LQG) on its shadow}. Given the rotating {LQBH}, we discuss its horizon, ergosurface, and regularity {as} $r \to 0$. Depending on the values of the specific angular momentum $a$ and the polymeric function $P$ arising from {LQG}, we {find} that the rotating solution we obtained can represent a regular black hole, a regular extreme black hole, or a regular spacetime {without horizon (a non-black-hole solution)}. We also {study} the effects of {LQG} and rotation, and {show} that, in addition to the specific angular momentum, the polymeric function {also} causes deformations in the size and shape of the black hole shadow. Interestingly, for a given value of $a$ and inclination angle $\theta_0$, the apparent size of the shadow monotonically decreases, and the shadow gets more distorted with increasing $P$. We also {consider the effects of $P$ on the deviations from the circularity of the shadow, and find} that the deviation from circularity increases with increasing $P$ for fixed values of $a$ and $\theta_0$. Additionally, we explore the observational implications of $P$ in comparison with the latest Event Horizon Telescope (EHT) observation of the supermassive black hole, M$87$. The connection between the shadow radius and quasinormal modes in the eikonal limit as well as {the} deflection of massive particles are also considered. |
gr-qc/9801010 | Beverly K. Berger | Beverly K. Berger | On the Nature of the Generic Big Bang | 7 pages, 5 figures, uses Revtex, epsf. Based on talk given at
Symposium on Frontiers of Fundamental Physics, Hyderabad, India, 11-12 Dec
1997 | null | null | null | gr-qc | null | Spatially homogeneous but possibly anisotropic cosmologies have two main
types of singularities: (1) asymptotically velocity term dominated (AVTD) -
(reversing the time direction) the universe evolves to the singularity with
fixed anisotropic collapse rates ; (2) Mixmaster-the anisotropic collapse rates
change in a deterministicaly chaotic way. Much less is known about spatially
inhomogeneous universes. It has been claimed that a generic universe would
evolve toward the singularity as a different Mixmaster universe at each spatial
point. I shall discuss how to predict whether a cosmology has an AVTD or
Mixmaster singularity and whether or not our numerical simulations agree with
these predictions.
| [
{
"created": "Tue, 6 Jan 1998 20:04:38 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Berger",
"Beverly K.",
""
]
] | Spatially homogeneous but possibly anisotropic cosmologies have two main types of singularities: (1) asymptotically velocity term dominated (AVTD) - (reversing the time direction) the universe evolves to the singularity with fixed anisotropic collapse rates ; (2) Mixmaster-the anisotropic collapse rates change in a deterministicaly chaotic way. Much less is known about spatially inhomogeneous universes. It has been claimed that a generic universe would evolve toward the singularity as a different Mixmaster universe at each spatial point. I shall discuss how to predict whether a cosmology has an AVTD or Mixmaster singularity and whether or not our numerical simulations agree with these predictions. |
gr-qc/9905047 | Felix Finster | Felix Finster, Niky Kamran, Joel Smoller, and Shing-Tung Yau | Non-Existence of Time-Periodic Solutions of the Dirac Equation in an
Axisymmetric Black Hole Geometry | 25 pages, 1 figure (published version), eigenvalues of angular
momentum in direction of symmetry axis corrected to be half odd integers | Commun.Pure Appl.Math. 53 (2000) 902-929, erratum Commun.Pure
Appl.Math. 53 (2000) 1201 | 10.1002/(SICI)1097-0312(200007)53:7<902::AID-CPA4>3.0.CO;2-4 | null | gr-qc math-ph math.DG math.MP | null | We prove that, in the non-extreme Kerr-Newman black hole geometry, the Dirac
equation has no normalizable, time-periodic solutions. A key tool is
Chandrasekhar's separation of the Dirac equation in this geometry. A similar
non-existence theorem is established in a more general class of stationary,
axisymmetric metrics in which the Dirac equation is known to be separable.
These results indicate that, in contrast with the classical situation of
massive particle orbits, a quantum mechanical Dirac particle must either
disappear into the black hole or escape to infinity.
| [
{
"created": "Fri, 14 May 1999 15:27:56 GMT",
"version": "v1"
},
{
"created": "Tue, 16 May 2000 09:28:57 GMT",
"version": "v2"
}
] | 2014-01-28 | [
[
"Finster",
"Felix",
""
],
[
"Kamran",
"Niky",
""
],
[
"Smoller",
"Joel",
""
],
[
"Yau",
"Shing-Tung",
""
]
] | We prove that, in the non-extreme Kerr-Newman black hole geometry, the Dirac equation has no normalizable, time-periodic solutions. A key tool is Chandrasekhar's separation of the Dirac equation in this geometry. A similar non-existence theorem is established in a more general class of stationary, axisymmetric metrics in which the Dirac equation is known to be separable. These results indicate that, in contrast with the classical situation of massive particle orbits, a quantum mechanical Dirac particle must either disappear into the black hole or escape to infinity. |
2403.09364 | Etera R. Livine | Etera R. Livine | Spinfoam Models for Quantum Gravity: Overview | 13 pages (entry prepared for the Encyclopedia of Mathematical Physics
2nd edition) | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | In the quest of a physical theory of quantum gravity, spin foam models, or in
short spinfoams, propose a well-defined path integral summing over quantized
discrete space-time geometries. At the crossroad of topological quantum field
theory, dynamical triangulations, Regge calculus, and loop quantum gravity,
this framework provides a non-perturbative and background independent
quantization of general relativity. It defines transition amplitudes between
quantum states of geometry, and gives a precise picture of the Planck scale
geometry with quantized areas and volumes. Gravity in three space-time
dimensions is exactly quantized in terms of the Ponzano-Regge state-sum and
Turaev-Viro topological invariants. In four space-time dimensions, gravity is
formulated as a topological theory, of the BF type, with extra constraints, and
hence quantized as a topological state-sum filled with defects. This leads to
the Engle-Pereira-Rovelli-Livine (EPRL) spinfoam model, that can be used for
explicit quantum gravity computations, for example for resolving the Big Bang
singularity by a bounce or in black-to-white hole transition probability
amplitudes.
| [
{
"created": "Thu, 14 Mar 2024 13:13:47 GMT",
"version": "v1"
}
] | 2024-03-15 | [
[
"Livine",
"Etera R.",
""
]
] | In the quest of a physical theory of quantum gravity, spin foam models, or in short spinfoams, propose a well-defined path integral summing over quantized discrete space-time geometries. At the crossroad of topological quantum field theory, dynamical triangulations, Regge calculus, and loop quantum gravity, this framework provides a non-perturbative and background independent quantization of general relativity. It defines transition amplitudes between quantum states of geometry, and gives a precise picture of the Planck scale geometry with quantized areas and volumes. Gravity in three space-time dimensions is exactly quantized in terms of the Ponzano-Regge state-sum and Turaev-Viro topological invariants. In four space-time dimensions, gravity is formulated as a topological theory, of the BF type, with extra constraints, and hence quantized as a topological state-sum filled with defects. This leads to the Engle-Pereira-Rovelli-Livine (EPRL) spinfoam model, that can be used for explicit quantum gravity computations, for example for resolving the Big Bang singularity by a bounce or in black-to-white hole transition probability amplitudes. |
gr-qc/0103004 | Ugo Moschella | A. Yu. Kamenshchik, U. Moschella, V. Pasquier | An alternative to quintessence | 8 pages, latex. References and a new section added | Phys.Lett. B511 (2001) 265-268 | 10.1016/S0370-2693(01)00571-8 | null | gr-qc | null | We consider a FRW cosmological model with an exotic fluid known as Chaplygin
gas. We show that the resulting evolution of the universe is not in
disagreement with the current observation of cosmic acceleration. The model
predict an increasing value for the effective cosmological constant.
| [
{
"created": "Thu, 1 Mar 2001 16:36:41 GMT",
"version": "v1"
},
{
"created": "Wed, 21 Mar 2001 16:30:06 GMT",
"version": "v2"
}
] | 2009-11-07 | [
[
"Kamenshchik",
"A. Yu.",
""
],
[
"Moschella",
"U.",
""
],
[
"Pasquier",
"V.",
""
]
] | We consider a FRW cosmological model with an exotic fluid known as Chaplygin gas. We show that the resulting evolution of the universe is not in disagreement with the current observation of cosmic acceleration. The model predict an increasing value for the effective cosmological constant. |
0707.3700 | Gianluca Mandanici | Gianluca Mandanici | Undeformed (additive) energy conservation law in Doubly Special
Relativity | 5 pages; A comparison with a previous analysis has been added | null | 10.1142/S0217732309030424 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | All the Doubly Special Relativity (DSR) models studied in literature so far
involve a deformation of the energy conservation rule that forces us to release
the hypothesis of the additivity of the energy for composite systems. In view
of the importance of the issue for a consistent formulation of a DSR
statistical mechanics and a DSR thermodynamics, we show that DSR models
preserving the usual (i.e. additive) energy conservation rule can be found.
These models allow the construction of a DSR-covariant extensive energy. The
implications of the analysis for the dynamics of DSR-covariant multiparticle
systems are also briefly discussed.
| [
{
"created": "Wed, 25 Jul 2007 10:08:43 GMT",
"version": "v1"
},
{
"created": "Tue, 11 Nov 2008 20:30:56 GMT",
"version": "v2"
}
] | 2015-05-13 | [
[
"Mandanici",
"Gianluca",
""
]
] | All the Doubly Special Relativity (DSR) models studied in literature so far involve a deformation of the energy conservation rule that forces us to release the hypothesis of the additivity of the energy for composite systems. In view of the importance of the issue for a consistent formulation of a DSR statistical mechanics and a DSR thermodynamics, we show that DSR models preserving the usual (i.e. additive) energy conservation rule can be found. These models allow the construction of a DSR-covariant extensive energy. The implications of the analysis for the dynamics of DSR-covariant multiparticle systems are also briefly discussed. |
2201.03274 | Jay Solanki | Jay Solanki and Volker Perlick | Photon sphere and shadow of a time-dependent black hole described by a
Vaidya metric | Some details corrected, one figure and several references added | Phys. Rev. D, 105:064056, Mar 2022 | 10.1103/PhysRevD.105.064056 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | In this paper we derive exact analytical formulas for the evolution of the
photon sphere and for the angular radius of the shadow in a special Vaidya
spacetime. The Vaidya metric describes a spherically symmetric object that
gains or loses mass, depending on a mass function $m(v)$ that can be freely
chosen. Here we consider the case that $m(v)$ is a linearly increasing or
decreasing function. The first case can serve as a simple model for an
accreting black hole, the second case for a (Hawking) radiating black hole.
With a linear mass function the Vaidya metric admits a conformal Killing vector
field which, together with the spherical symmetry, gives us enough constants of
motion for analytically calculating the light-like geodesics. Both in the
accreting and in the radiating case, we first calculate the light-like
geodesics, the photon sphere, the angular radius of the shadow, and the
red-shift of light in coordinates in which the metric is manifestly conformally
static, then we analyze the photon sphere and the shadow in the original
Eddington-Finkelstein-like Vaidya coordinates.
| [
{
"created": "Mon, 10 Jan 2022 10:43:16 GMT",
"version": "v1"
},
{
"created": "Wed, 9 Mar 2022 04:12:03 GMT",
"version": "v2"
}
] | 2022-04-01 | [
[
"Solanki",
"Jay",
""
],
[
"Perlick",
"Volker",
""
]
] | In this paper we derive exact analytical formulas for the evolution of the photon sphere and for the angular radius of the shadow in a special Vaidya spacetime. The Vaidya metric describes a spherically symmetric object that gains or loses mass, depending on a mass function $m(v)$ that can be freely chosen. Here we consider the case that $m(v)$ is a linearly increasing or decreasing function. The first case can serve as a simple model for an accreting black hole, the second case for a (Hawking) radiating black hole. With a linear mass function the Vaidya metric admits a conformal Killing vector field which, together with the spherical symmetry, gives us enough constants of motion for analytically calculating the light-like geodesics. Both in the accreting and in the radiating case, we first calculate the light-like geodesics, the photon sphere, the angular radius of the shadow, and the red-shift of light in coordinates in which the metric is manifestly conformally static, then we analyze the photon sphere and the shadow in the original Eddington-Finkelstein-like Vaidya coordinates. |
1510.08298 | Hor\'acio Santana Vieira | H. S. Vieira | Resonant frequencies of the hydrodynamic vortex | 9 pages, 1 figure | Int. J. Mod. Phys. D 26 (2017) 1750035 | 10.1142/S0218271817500353 | null | gr-qc cond-mat.other math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the sound perturbation of the hydrodynamic vortex geometry and
present an exact expression for the resonant frequencies (quasispectrum) of
this geometry. Exact solution for the radial part of the covariant Klein-Gordon
equation in this spacetime is obtained, and is given in terms of the double
confluent Heun functions. We found that the resonant frequencies are complex
number.
| [
{
"created": "Wed, 28 Oct 2015 13:17:49 GMT",
"version": "v1"
},
{
"created": "Sun, 25 Sep 2016 15:17:10 GMT",
"version": "v2"
}
] | 2016-09-27 | [
[
"Vieira",
"H. S.",
""
]
] | We study the sound perturbation of the hydrodynamic vortex geometry and present an exact expression for the resonant frequencies (quasispectrum) of this geometry. Exact solution for the radial part of the covariant Klein-Gordon equation in this spacetime is obtained, and is given in terms of the double confluent Heun functions. We found that the resonant frequencies are complex number. |
1101.3660 | J. Fernando Barbero G. | Ivan Agullo, J. Fernando Barbero G., Enrique F. Borja, Jacobo
Diaz-Polo, Eduardo J. S. Villase\~nor | Detailed black hole state counting in loop quantum gravity | null | Phys.Rev.D82:084029,2010 | 10.1103/PhysRevD.82.084029 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We give a complete and detailed description of the computation of black hole
entropy in loop quantum gravity by employing the most recently introduced
number-theoretic and combinatorial methods. The use of these techniques allows
us to perform a detailed analysis of the precise structure of the entropy
spectrum for small black holes, showing some relevant features that were not
discernible in previous computations. The ability to manipulate and understand
the spectrum up to the level of detail that we describe in the paper is a
crucial step towards obtaining the behavior of entropy in the asymptotic (large
horizon area) regime.
| [
{
"created": "Wed, 19 Jan 2011 10:48:02 GMT",
"version": "v1"
}
] | 2015-03-17 | [
[
"Agullo",
"Ivan",
""
],
[
"G.",
"J. Fernando Barbero",
""
],
[
"Borja",
"Enrique F.",
""
],
[
"Diaz-Polo",
"Jacobo",
""
],
[
"Villaseñor",
"Eduardo J. S.",
""
]
] | We give a complete and detailed description of the computation of black hole entropy in loop quantum gravity by employing the most recently introduced number-theoretic and combinatorial methods. The use of these techniques allows us to perform a detailed analysis of the precise structure of the entropy spectrum for small black holes, showing some relevant features that were not discernible in previous computations. The ability to manipulate and understand the spectrum up to the level of detail that we describe in the paper is a crucial step towards obtaining the behavior of entropy in the asymptotic (large horizon area) regime. |
gr-qc/9411036 | Vassilevich Dmitri | Dmitri V. Vassilevich | QED on Curved Background and on Manifolds with Boundaries: Unitarity
versus Covariance | 29 pages, LaTEX, no figures | Phys.Rev. D52 (1995) 999-1010 | 10.1103/PhysRevD.52.999 | ICTP preprint IC/94/359 | gr-qc hep-th | null | Some recent results show that the covariant path integral and the integral
over physical degrees of freedom give contradicting results on curved
background and on manifolds with boundaries. This looks like a conflict between
unitarity and covariance. We argue that this effect is due to the use of
non-covariant measure on the space of physical degrees of freedom. Starting
with the reduced phase space path integral and using covariant measure
throughout computations we recover standard path integral in the Lorentz gauge
and the Moss and Poletti BRST-invariant boundary conditions. We also
demonstrate by direct calculations that in the approach based on Gaussian path
integral on the space of physical degrees of freedom some basic symmetries are
broken.
| [
{
"created": "Mon, 14 Nov 1994 15:40:30 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Vassilevich",
"Dmitri V.",
""
]
] | Some recent results show that the covariant path integral and the integral over physical degrees of freedom give contradicting results on curved background and on manifolds with boundaries. This looks like a conflict between unitarity and covariance. We argue that this effect is due to the use of non-covariant measure on the space of physical degrees of freedom. Starting with the reduced phase space path integral and using covariant measure throughout computations we recover standard path integral in the Lorentz gauge and the Moss and Poletti BRST-invariant boundary conditions. We also demonstrate by direct calculations that in the approach based on Gaussian path integral on the space of physical degrees of freedom some basic symmetries are broken. |
1307.2637 | Lijing Shao | Lijing Shao, Norbert Wex | New limits on the violation of local position invariance of gravity | 13 pages, 4 figures; accepted by Classical and Quantum Gravity | Class. Quantum Grav. 30 (2013) 165020 | 10.1088/0264-9381/30/16/165020 | null | gr-qc astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Within the parameterized post-Newtonian (PPN) formalism, there could be an
anisotropy of local gravity induced by an external matter distribution, even
for a fully conservative metric theory of gravity. It reflects the breakdown of
the local position invariance of gravity and, within the PPN formalism, is
characterized by the Whitehead parameter $\xi$. We present three different
kinds of observation, from the Solar system and radio pulsars, to constrain it.
The most stringent limit comes from recent results on the extremely stable
pulse profiles of solitary millisecond pulsars, that gives $|\hat \xi| < 3.9
\times 10^{-9}$ (95% CL), where the hat denotes the strong-field generalization
of $\xi$. This limit is six orders of magnitude more constraining than the
current best limit from superconducting gravimeter experiments. It can be
converted into an upper limit of $\sim 4 \times 10^{-16}$ on the spatial
anisotropy of the gravitational constant.
| [
{
"created": "Wed, 10 Jul 2013 00:36:39 GMT",
"version": "v1"
}
] | 2013-08-02 | [
[
"Shao",
"Lijing",
""
],
[
"Wex",
"Norbert",
""
]
] | Within the parameterized post-Newtonian (PPN) formalism, there could be an anisotropy of local gravity induced by an external matter distribution, even for a fully conservative metric theory of gravity. It reflects the breakdown of the local position invariance of gravity and, within the PPN formalism, is characterized by the Whitehead parameter $\xi$. We present three different kinds of observation, from the Solar system and radio pulsars, to constrain it. The most stringent limit comes from recent results on the extremely stable pulse profiles of solitary millisecond pulsars, that gives $|\hat \xi| < 3.9 \times 10^{-9}$ (95% CL), where the hat denotes the strong-field generalization of $\xi$. This limit is six orders of magnitude more constraining than the current best limit from superconducting gravimeter experiments. It can be converted into an upper limit of $\sim 4 \times 10^{-16}$ on the spatial anisotropy of the gravitational constant. |
1307.0034 | Igor Tanatarov | I. V. Tanatarov and O. B. Zaslavskii | Ba\~{n}ados-Silk-West effect with nongeodesic particles: extremal
horizons | 36 pages. To be published in PRD. Presentation improved, matches
accepted version | Phys. Rev. D 88, 064036 (2013) | 10.1103/PhysRevD.88.064036 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Ba\~{n}ados-Silk-West (BSW) effect consists in the possibility to obtain
arbitrarily large energy $E_{c.m.}$ in the centre of mass frame of two
colliding particles near the black hole horizon. One of the common beliefs was
that the action of force on these particles (say, due to gravitational
radiation) should necessarily restrict the growth of $E_{c.m.}$. We consider
extremal horizons and develop a model-independent approach and analyze the
conditions for the force to preserve or kill the effect, using the frames
attached both to observers orbiting the black hole and to ones crossing the
horizon. We argue that the aforementioned expectations are not confirmed. Under
rather general assumptions, the BSW effect survives. For equatorial motion it
is only required that in the proper frame the radial component of the force be
finite, while the azimuthal one tend to zero not too slowly. If the latter
condition is violated, we evaluate $E_{c.m.}$, which becomes indeed restricted
but remains very large for small forces.
| [
{
"created": "Fri, 28 Jun 2013 21:47:34 GMT",
"version": "v1"
},
{
"created": "Sun, 8 Sep 2013 14:41:34 GMT",
"version": "v2"
}
] | 2013-09-19 | [
[
"Tanatarov",
"I. V.",
""
],
[
"Zaslavskii",
"O. B.",
""
]
] | The Ba\~{n}ados-Silk-West (BSW) effect consists in the possibility to obtain arbitrarily large energy $E_{c.m.}$ in the centre of mass frame of two colliding particles near the black hole horizon. One of the common beliefs was that the action of force on these particles (say, due to gravitational radiation) should necessarily restrict the growth of $E_{c.m.}$. We consider extremal horizons and develop a model-independent approach and analyze the conditions for the force to preserve or kill the effect, using the frames attached both to observers orbiting the black hole and to ones crossing the horizon. We argue that the aforementioned expectations are not confirmed. Under rather general assumptions, the BSW effect survives. For equatorial motion it is only required that in the proper frame the radial component of the force be finite, while the azimuthal one tend to zero not too slowly. If the latter condition is violated, we evaluate $E_{c.m.}$, which becomes indeed restricted but remains very large for small forces. |
1102.1688 | Frank Hellmann | Frank Hellmann | State Sums and Geometry | PhD Thesis, 106 pages | null | null | null | gr-qc math-ph math.MP | http://creativecommons.org/licenses/by-nc-sa/3.0/ | In this thesis I review the definition of topological quantum field theories
through state sums on triangulated manifolds. I describe the construction of
state sum invariants of 3-manifolds from a graphical calculus and show how to
evaluate the invariants as boundary amplitudes. I review how to define such a
graphical calculus through SU(2) representation theory. I then review various
geometricity results for the representation theory of SU(2), Spin(4) and
SL(2,C), and define coherent boundary manifolds for state sums based on these
representations. I derive the asymptotic geometry of the SU(2) based
Ponzano-Regge invariant in three dimensions, and the SU(2) based Ooguri models
amplitude in four dimensions. As a corollary to the latter results I derive the
asymptotic behaviour of various recently proposed spin foam models motivated
from the Plebanski formulation of general relativity. Finally the asymptotic
geometry of the SL(2,C) based model is derived.
| [
{
"created": "Tue, 8 Feb 2011 18:57:44 GMT",
"version": "v1"
}
] | 2015-03-18 | [
[
"Hellmann",
"Frank",
""
]
] | In this thesis I review the definition of topological quantum field theories through state sums on triangulated manifolds. I describe the construction of state sum invariants of 3-manifolds from a graphical calculus and show how to evaluate the invariants as boundary amplitudes. I review how to define such a graphical calculus through SU(2) representation theory. I then review various geometricity results for the representation theory of SU(2), Spin(4) and SL(2,C), and define coherent boundary manifolds for state sums based on these representations. I derive the asymptotic geometry of the SU(2) based Ponzano-Regge invariant in three dimensions, and the SU(2) based Ooguri models amplitude in four dimensions. As a corollary to the latter results I derive the asymptotic behaviour of various recently proposed spin foam models motivated from the Plebanski formulation of general relativity. Finally the asymptotic geometry of the SL(2,C) based model is derived. |
gr-qc/0501063 | Elliot Fischer | Elliot Fischer | Similarity Solutions of the Einstein-Maxwell equations with 1 Killing
Vector | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | New similarity variables are introduced for the Einstein - Maxwell equations
with one Killing vector that reduce the non-linear partial differential
equations in three independent variables to ordinary differential equations.
These similarity variables are the extensions of those previously found for the
Einstein-Maxwell equations with two Killing vectors. The resulting equations
are then solved, providing new solutions of the Einstein - Maxwell equations
with one Killing Vector.
| [
{
"created": "Thu, 20 Jan 2005 14:51:07 GMT",
"version": "v1"
},
{
"created": "Sun, 28 Feb 2016 17:03:25 GMT",
"version": "v2"
}
] | 2016-03-01 | [
[
"Fischer",
"Elliot",
""
]
] | New similarity variables are introduced for the Einstein - Maxwell equations with one Killing vector that reduce the non-linear partial differential equations in three independent variables to ordinary differential equations. These similarity variables are the extensions of those previously found for the Einstein-Maxwell equations with two Killing vectors. The resulting equations are then solved, providing new solutions of the Einstein - Maxwell equations with one Killing Vector. |
1910.04678 | Filipe Mena | Artur Alho, Vitor Bessa, Filipe C. Mena | Global dynamics of Yang-Mills field and perfect-fluid Robertson-Walker
cosmologies | 22 pages, 11 figures | J. Math. Phys. 61 (2020) 032502 | 10.1063/1.5139879 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We apply a new global dynamical systems formulation to flat Robertson-Walker
cosmologies with a massless and massive Yang-Mills field and a perfect-fluid
with linear equation of state as the matter sources. This allows us to give
proofs concerning the global dynamics of the models including asymptotic
source-dominance towards the past and future time directions. For the pure
massless Yang-Mills field, we also contextualize well-known explicit solutions
in a global (compact) state space picture.
| [
{
"created": "Thu, 10 Oct 2019 16:32:05 GMT",
"version": "v1"
},
{
"created": "Mon, 20 Apr 2020 15:53:19 GMT",
"version": "v2"
}
] | 2020-04-29 | [
[
"Alho",
"Artur",
""
],
[
"Bessa",
"Vitor",
""
],
[
"Mena",
"Filipe C.",
""
]
] | We apply a new global dynamical systems formulation to flat Robertson-Walker cosmologies with a massless and massive Yang-Mills field and a perfect-fluid with linear equation of state as the matter sources. This allows us to give proofs concerning the global dynamics of the models including asymptotic source-dominance towards the past and future time directions. For the pure massless Yang-Mills field, we also contextualize well-known explicit solutions in a global (compact) state space picture. |
gr-qc/0401112 | Miguel Sanchez | Antonio N. Bernal, Miguel S\'anchez | Smoothness of time functions and the metric splitting of globally
hyperbolic spacetimes | 9 pages, Latex, to appear in Commun. Math. Phys. Some comments on
time functions and stably causal spacetimes are incorporated, and referred to
gr-qc/0411143 for further details | Commun.Math.Phys. 257 (2005) 43-50 | 10.1007/s00220-005-1346-1 | null | gr-qc math.DG | null | The folk questions in Lorentzian Geometry, which concerns the smoothness of
time functions and slicings by Cauchy hypersurfaces, are solved by giving
simple proofs of: (a) any globally hyperbolic spacetime $(M,g)$ admits a smooth
time function $\tau$ whose levels are spacelike Cauchy hyperfurfaces and, thus,
also a smooth global splitting $M= \R \times {\cal S}$, $g= - \beta(\tau,x)
d\tau^2 + \bar g_\tau $, (b) if a spacetime $M$ admits a (continuous) time
function $t$ (i.e., it is stably causal) then it admits a smooth (time)
function $\tau$ with timelike gradient $\nabla \tau$ on all $M$.
| [
{
"created": "Wed, 28 Jan 2004 16:38:07 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Nov 2004 11:20:09 GMT",
"version": "v2"
},
{
"created": "Tue, 15 Feb 2005 18:45:19 GMT",
"version": "v3"
}
] | 2009-11-10 | [
[
"Bernal",
"Antonio N.",
""
],
[
"Sánchez",
"Miguel",
""
]
] | The folk questions in Lorentzian Geometry, which concerns the smoothness of time functions and slicings by Cauchy hypersurfaces, are solved by giving simple proofs of: (a) any globally hyperbolic spacetime $(M,g)$ admits a smooth time function $\tau$ whose levels are spacelike Cauchy hyperfurfaces and, thus, also a smooth global splitting $M= \R \times {\cal S}$, $g= - \beta(\tau,x) d\tau^2 + \bar g_\tau $, (b) if a spacetime $M$ admits a (continuous) time function $t$ (i.e., it is stably causal) then it admits a smooth (time) function $\tau$ with timelike gradient $\nabla \tau$ on all $M$. |
1802.05562 | Fatimah Shojai | S. Cheraghchi, F. Shojai | On the initial conditions of scalar and tensor fluctuations in
$f(R,\phi)$ gravity | 11 pages | Eur. Phys. J. C (2018) 78:384 | 10.1140/epjc/s10052-018-5878-x | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We have considered the perturbation equations governing the growth of
fluctuations in generalized scalar tensor theory during inflation. we have
found that the scalar metric perturbations at very early times are negligible
compared with the scalar field perturbation, just like general relativity. At
sufficiently early times, when $q/a\gg H$, we have obtained the metric and
scalar field perturbation in the form of WKB solutions up to an undetermined
coefficient. Then we have quantized the scalar fluctuations and expanded the
metric and the scalar field perturbations with the help of annihilation and
creation operators of the scalar field perturbation. The standard commutation
relations of annihilation and creation operators fix the unknown coefficient.
Going over to the gauge invariant quantities which are conserved beyond the
horizon, we have obtained the initial condition of the generalized
Mukhanov-Sasaki equation. And a similar procedure is performed for the case of
tensor metric perturbation.
| [
{
"created": "Thu, 15 Feb 2018 14:28:56 GMT",
"version": "v1"
}
] | 2018-05-23 | [
[
"Cheraghchi",
"S.",
""
],
[
"Shojai",
"F.",
""
]
] | We have considered the perturbation equations governing the growth of fluctuations in generalized scalar tensor theory during inflation. we have found that the scalar metric perturbations at very early times are negligible compared with the scalar field perturbation, just like general relativity. At sufficiently early times, when $q/a\gg H$, we have obtained the metric and scalar field perturbation in the form of WKB solutions up to an undetermined coefficient. Then we have quantized the scalar fluctuations and expanded the metric and the scalar field perturbations with the help of annihilation and creation operators of the scalar field perturbation. The standard commutation relations of annihilation and creation operators fix the unknown coefficient. Going over to the gauge invariant quantities which are conserved beyond the horizon, we have obtained the initial condition of the generalized Mukhanov-Sasaki equation. And a similar procedure is performed for the case of tensor metric perturbation. |
0904.3596 | J. Ponce de Leon | J. Ponce de Leon | Levi-Civita spacetimes in multidimensional theories | 7 pages. Accepted for publication in Mod. Phys. Lett. A (MPLA) | Mod.Phys.Lett.A24:1659-1667,2009 | 10.1142/S0217732309031004 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We obtain the most general static cylindrically symmetric vacuum solutions of
the Einstein field equations in $(4 + N)$ dimensions. Under the assumption of
separation of variables, we construct a family of Levi-Civita-Kasner vacuum
solutions in $(4 + N)$. We discuss the dimensional reduction of the static
solutions. Depending on the reduction procedure, they can be interpreted either
as a scalar-vacuum generalization of Levi-Civita spacetimes, or as the
effective 4D vacuum spacetime outside of an idealized string in braneworld
theory.
| [
{
"created": "Thu, 23 Apr 2009 04:02:35 GMT",
"version": "v1"
}
] | 2009-08-13 | [
[
"de Leon",
"J. Ponce",
""
]
] | We obtain the most general static cylindrically symmetric vacuum solutions of the Einstein field equations in $(4 + N)$ dimensions. Under the assumption of separation of variables, we construct a family of Levi-Civita-Kasner vacuum solutions in $(4 + N)$. We discuss the dimensional reduction of the static solutions. Depending on the reduction procedure, they can be interpreted either as a scalar-vacuum generalization of Levi-Civita spacetimes, or as the effective 4D vacuum spacetime outside of an idealized string in braneworld theory. |
1105.6194 | Ion I. Cotaescu | Ion I. Cotaescu | Discrete O(1,4) transformations and new scalar quantum modes on the de
Sitter spacetime | 6 pages no figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is shown that the isometry group of the de Sitter spacetime includes two
different three-dimensional Abelian subgroups which transform between
themselves through a discrete isometry corresponding to the time reversal in
the five-dimensional Minkowski spacetime embedding the de Sitter one. The
eigenfunctions of the generators of these Abelian subgroups form two different
sets of quantum modes correlated by the mentioned isometry.
| [
{
"created": "Tue, 31 May 2011 07:58:07 GMT",
"version": "v1"
}
] | 2011-06-01 | [
[
"Cotaescu",
"Ion I.",
""
]
] | It is shown that the isometry group of the de Sitter spacetime includes two different three-dimensional Abelian subgroups which transform between themselves through a discrete isometry corresponding to the time reversal in the five-dimensional Minkowski spacetime embedding the de Sitter one. The eigenfunctions of the generators of these Abelian subgroups form two different sets of quantum modes correlated by the mentioned isometry. |
gr-qc/0108027 | F. Siddhartha Guzman | T. Matos and F. S. Guzman | On the Space Time of a Galaxy | 8 pages REVTeX, 11 eps figures | Class.Quant.Grav. 18 (2001) 5055-5064 | 10.1088/0264-9381/18/23/303 | null | gr-qc astro-ph hep-th | null | We present an exact solution of the averaged Einstein's field equations in
the presence of two real scalar fields and a component of dust with spherical
symmetry. We suggest that the space-time found provides the characteristics
required by a galactic model that could explain the supermassive central object
and the dark matter halo at once, since one of the fields constitutes a central
oscillaton surrounded by the dust and the other scalar field distributes far
from the coordinate center and can be interpreted as a halo. We show the
behavior of the rotation curves all along the background. Thus, the solution
could be a first approximation of a ``long exposition photograph'' of a galaxy.
| [
{
"created": "Thu, 9 Aug 2001 02:26:46 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Matos",
"T.",
""
],
[
"Guzman",
"F. S.",
""
]
] | We present an exact solution of the averaged Einstein's field equations in the presence of two real scalar fields and a component of dust with spherical symmetry. We suggest that the space-time found provides the characteristics required by a galactic model that could explain the supermassive central object and the dark matter halo at once, since one of the fields constitutes a central oscillaton surrounded by the dust and the other scalar field distributes far from the coordinate center and can be interpreted as a halo. We show the behavior of the rotation curves all along the background. Thus, the solution could be a first approximation of a ``long exposition photograph'' of a galaxy. |
gr-qc/0005124 | Gaetano Lambiase | V. Bozza, A. Feoli, G. Papini, G. Scarpetta | Maximal Acceleration Effects in Reissner-Nordstrom Space | LaTex file, 5 figures, no tables, to appear in Phys. Lett. A | Phys.Lett. A271 (2000) 35-43 | 10.1016/S0375-9601(00)00351-0 | null | gr-qc | null | The dynamics of a relativistic particle in a Reissner-Nordstrom background is
studied using Caianiello model with maximal acceleration. The behaviour of the
particle, embedded in a new effective geometry, changes with respect to the
classical scenario because of the formation of repulsive potential barriers
near the horizon. Black hole formation by accretion of massive particles is not
therefore a viable process in the model. At the same time, the naked
singularity remains largely unaffected by maximal acceleration corrections.
| [
{
"created": "Mon, 29 May 2000 15:29:54 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Bozza",
"V.",
""
],
[
"Feoli",
"A.",
""
],
[
"Papini",
"G.",
""
],
[
"Scarpetta",
"G.",
""
]
] | The dynamics of a relativistic particle in a Reissner-Nordstrom background is studied using Caianiello model with maximal acceleration. The behaviour of the particle, embedded in a new effective geometry, changes with respect to the classical scenario because of the formation of repulsive potential barriers near the horizon. Black hole formation by accretion of massive particles is not therefore a viable process in the model. At the same time, the naked singularity remains largely unaffected by maximal acceleration corrections. |
1410.5463 | Fabio Dahia | F. Dahia and Alex de Albuquerque Silva | Classical tests of General Relativity in thick branes | null | null | 10.1140/epjc/s10052-015-3307-y | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Classical tests of General Relativity in braneworld scenarios have been
investigated recently with the purpose of posing observational constraints on
parameters of some models of infinitely thin brane. Here we consider the motion
of test particles in a thick brane scenario that corresponds to a regularized
version of the Garriga-Tanaka solution, which describes a black hole solution
in RSII model, in the weak field regime. By adapting a mechanism previously
formulated in order to describe the confinement of massive tests particles in a
domain wall (that simulates classically the trapping of the Dirac field in a
domain wall), we study the influence of the brane thickness on the
four-dimensional (4D) path of massless particles. Although the geometry is not
warped and, therefore, the bound motion in the transverse direction is not
decoupled from the movement in the 4D-world, we can find an explicit solution
for the light deflection and the time delay, if the motion in the fifth
direction is a high frequency oscillation. We verify that, owing to the
transverse motion, the light deflection and the time delay depend on the energy
of the light rays. This feature may lead to the phenomenon of gravitational
rainbow. We also consider the problem from a semi-classical perspective,
investigating the effects of the brane thickness on the motion of the zero-mode
in the 4D-world.
| [
{
"created": "Mon, 20 Oct 2014 21:02:04 GMT",
"version": "v1"
}
] | 2015-06-23 | [
[
"Dahia",
"F.",
""
],
[
"Silva",
"Alex de Albuquerque",
""
]
] | Classical tests of General Relativity in braneworld scenarios have been investigated recently with the purpose of posing observational constraints on parameters of some models of infinitely thin brane. Here we consider the motion of test particles in a thick brane scenario that corresponds to a regularized version of the Garriga-Tanaka solution, which describes a black hole solution in RSII model, in the weak field regime. By adapting a mechanism previously formulated in order to describe the confinement of massive tests particles in a domain wall (that simulates classically the trapping of the Dirac field in a domain wall), we study the influence of the brane thickness on the four-dimensional (4D) path of massless particles. Although the geometry is not warped and, therefore, the bound motion in the transverse direction is not decoupled from the movement in the 4D-world, we can find an explicit solution for the light deflection and the time delay, if the motion in the fifth direction is a high frequency oscillation. We verify that, owing to the transverse motion, the light deflection and the time delay depend on the energy of the light rays. This feature may lead to the phenomenon of gravitational rainbow. We also consider the problem from a semi-classical perspective, investigating the effects of the brane thickness on the motion of the zero-mode in the 4D-world. |
2106.04343 | Lloyd Kannenberg | L. Kannenberg | A Note on Rainich's Condition in the Null Case | 5 pages, no figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is shown that bivectors are not necessary to satisfy the Rainich
conditions in the null case.
| [
{
"created": "Mon, 7 Jun 2021 13:32:13 GMT",
"version": "v1"
}
] | 2021-06-09 | [
[
"Kannenberg",
"L.",
""
]
] | It is shown that bivectors are not necessary to satisfy the Rainich conditions in the null case. |
0708.3145 | Yong-Wan Kim | Yun Soo Myung, Yong-Wan Kim, Young-Jai Park | Thermodynamics of regular black hole | 20 pages, 6 figures, version to appear in GRG | null | 10.1007/s10714-008-0690-9 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate thermodynamics for a magnetically charged regular black hole
(MCRBH), which comes from the action of general relativity and nonlinear
electromagnetics, comparing with the Reissner-Norstr\"om (RN) black hole in
both four and two dimensions after dimensional reduction. We find that there is
no thermodynamic difference between the regular and RN black holes for a fixed
charge $Q$ in both dimensions. This means that the condition for either
singularity or regularity at the origin of coordinate does not affect the
thermodynamics of black hole. Furthermore, we describe the near-horizon AdS$_2$
thermodynamics of the MCRBH with the connection of the Jackiw-Teitelboim
theory. We also identify the near-horizon entropy as the statistical entropy by
using the AdS$_2$/CFT$_1$ correspondence.
| [
{
"created": "Thu, 23 Aug 2007 09:00:14 GMT",
"version": "v1"
},
{
"created": "Mon, 27 Aug 2007 08:22:18 GMT",
"version": "v2"
},
{
"created": "Fri, 28 Sep 2007 08:23:22 GMT",
"version": "v3"
},
{
"created": "Sun, 21 Sep 2008 15:27:05 GMT",
"version": "v4"
}
] | 2009-11-13 | [
[
"Myung",
"Yun Soo",
""
],
[
"Kim",
"Yong-Wan",
""
],
[
"Park",
"Young-Jai",
""
]
] | We investigate thermodynamics for a magnetically charged regular black hole (MCRBH), which comes from the action of general relativity and nonlinear electromagnetics, comparing with the Reissner-Norstr\"om (RN) black hole in both four and two dimensions after dimensional reduction. We find that there is no thermodynamic difference between the regular and RN black holes for a fixed charge $Q$ in both dimensions. This means that the condition for either singularity or regularity at the origin of coordinate does not affect the thermodynamics of black hole. Furthermore, we describe the near-horizon AdS$_2$ thermodynamics of the MCRBH with the connection of the Jackiw-Teitelboim theory. We also identify the near-horizon entropy as the statistical entropy by using the AdS$_2$/CFT$_1$ correspondence. |
gr-qc/0508032 | Edward Porter | Edward K. Porter | Detecting gravitational waves from test-mass bodies orbiting a Kerr
black hole with P-approximant templates | 11 Pages - 9 figures. Accepted for publication. Proceedings of GWDAW
9. Special edition of Classical and Quantum Gravity | Class.Quant.Grav. 22 (2005) S1211-S1222 | 10.1088/0264-9381/22/18/S35 | null | gr-qc | null | In this study we apply post-Newtonian (T-approximants) and resummed
post-Newtonian (P-approximants) to the case of a test-particle in equatorial
orbit around a Kerr black hole. We compare the two approximants by measuring
their effectualness (i.e. larger overlaps with the exact signal), and
faithfulness (i.e. smaller biases while measuring the parameters of the signal)
with the exact (numerical) waveforms. We find that in the case of prograde
orbits, T-approximant templates obtain an effectualness of ~0.99 for spins q <
0.75. For 0.75 < q < 0.95, the effectualness drops to about 0.82. The
P-approximants achieve effectualness of > 0.99 for all spins up to q = 0.95.
The bias in the estimation of parameters is much lower in the case of
P-approximants than T-approximants. We find that P-approximants are both
effectual and faithful and should be more effective than T-approximants as a
detection template family when q > 0. For q < 0 both T- and P-approximants
perform equally well so that either of them could be used as a detection
template family. However, for parameter estimation, the P-approximant templates
still outperforms the T-approximants.
| [
{
"created": "Tue, 9 Aug 2005 12:51:35 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Porter",
"Edward K.",
""
]
] | In this study we apply post-Newtonian (T-approximants) and resummed post-Newtonian (P-approximants) to the case of a test-particle in equatorial orbit around a Kerr black hole. We compare the two approximants by measuring their effectualness (i.e. larger overlaps with the exact signal), and faithfulness (i.e. smaller biases while measuring the parameters of the signal) with the exact (numerical) waveforms. We find that in the case of prograde orbits, T-approximant templates obtain an effectualness of ~0.99 for spins q < 0.75. For 0.75 < q < 0.95, the effectualness drops to about 0.82. The P-approximants achieve effectualness of > 0.99 for all spins up to q = 0.95. The bias in the estimation of parameters is much lower in the case of P-approximants than T-approximants. We find that P-approximants are both effectual and faithful and should be more effective than T-approximants as a detection template family when q > 0. For q < 0 both T- and P-approximants perform equally well so that either of them could be used as a detection template family. However, for parameter estimation, the P-approximant templates still outperforms the T-approximants. |
0907.2154 | Christian Corda | Lorenzo Iorio and Christian Corda | Gravitomagnetic effect in gravitational waves | To appear in Proceedings of the 7th International Conference of
Numerical Analysis and Applied Mathematics, Rethymno, Crete (near to Chania),
Greece, 18-22 September 2009 | AIP Conf. Proc. Volume 1168, pp. 1072-1076, September 9, 2009 | 10.1063/1.3241239 | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | After an introduction emphasizing the importance of the gravitomag- netic
effect in general relativity, with a resume of some space-based appli- cations,
we discuss the so-called magnetic components of gravitational waves (GWs),
which have to be taken into account in the context of the total response
functions of interferometers for GWs propagating from ar- bitrary directions.
| [
{
"created": "Mon, 13 Jul 2009 12:52:41 GMT",
"version": "v1"
}
] | 2010-01-22 | [
[
"Iorio",
"Lorenzo",
""
],
[
"Corda",
"Christian",
""
]
] | After an introduction emphasizing the importance of the gravitomag- netic effect in general relativity, with a resume of some space-based appli- cations, we discuss the so-called magnetic components of gravitational waves (GWs), which have to be taken into account in the context of the total response functions of interferometers for GWs propagating from ar- bitrary directions. |
0710.5552 | Christian L\"ubbe | Christian L\"ubbe and Paul Tod | An extension theorem for conformal gauge singularities | 43 pages, no figures, version as published in JMP, small changes,
updated references | J.Math.Phys.50:112501,2009 | 10.1063/1.3239509 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyse conformal gauge, or isotropic, singularities in cosmological
models in general relativity. Using the calculus of tractors, we find
conditions in terms of tractor curvature for a local extension of the conformal
structure through a cosmological singularity and prove a local extension
theorem.
| [
{
"created": "Mon, 29 Oct 2007 23:40:54 GMT",
"version": "v1"
},
{
"created": "Tue, 10 Jun 2008 16:11:09 GMT",
"version": "v2"
},
{
"created": "Thu, 19 Nov 2009 11:52:07 GMT",
"version": "v3"
}
] | 2010-01-07 | [
[
"Lübbe",
"Christian",
""
],
[
"Tod",
"Paul",
""
]
] | We analyse conformal gauge, or isotropic, singularities in cosmological models in general relativity. Using the calculus of tractors, we find conditions in terms of tractor curvature for a local extension of the conformal structure through a cosmological singularity and prove a local extension theorem. |
1911.00528 | Francisco Nogueira Lima | A. S. Ribeiro, G. Alencar, R. R. Landim, F. N. Lima | Mass spectrum of scalar and gauge fields in the cosmological multiply
warped brane-world | F. N. Lima left the work | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we compute the massive modes of scalar and gauge fields in a
multiply warped brane-world scenario in six-dimensional spacetime with a
Freedman-Robertson-Walker (FRW) metric. The massive Kaluza-Klein (KK) modes of
the fields are split in two mass towers due to the presence of the warped in
both dimensions. This does not occurs in the standard Randall-Sundrum (RS)
model. We investigate the dependence of the mass spectrum on Hubble constant.
Lighter massive modes of the fields are found, whereby it is possible to infer
that scalar and bosonic matter can directly influence in universe expansion.
| [
{
"created": "Fri, 1 Nov 2019 18:03:14 GMT",
"version": "v1"
},
{
"created": "Tue, 12 Nov 2019 01:22:28 GMT",
"version": "v2"
}
] | 2019-11-13 | [
[
"Ribeiro",
"A. S.",
""
],
[
"Alencar",
"G.",
""
],
[
"Landim",
"R. R.",
""
],
[
"Lima",
"F. N.",
""
]
] | In this paper, we compute the massive modes of scalar and gauge fields in a multiply warped brane-world scenario in six-dimensional spacetime with a Freedman-Robertson-Walker (FRW) metric. The massive Kaluza-Klein (KK) modes of the fields are split in two mass towers due to the presence of the warped in both dimensions. This does not occurs in the standard Randall-Sundrum (RS) model. We investigate the dependence of the mass spectrum on Hubble constant. Lighter massive modes of the fields are found, whereby it is possible to infer that scalar and bosonic matter can directly influence in universe expansion. |
1401.2057 | Giacomo Rosati | Francesco Cianfrani, Jerzy Kowalski-Glikman, Giacomo Rosati | Generally covariant formulation of Relative Locality in curved spacetime | null | Phys. Rev. D 89, 044039 (2014) | 10.1103/PhysRevD.89.044039 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct a theory of particles moving in curved both momentum space and
spacetime, being a generalization of Relative Locality. We find that in order
to construct such theory, with desired symmetries, including the general
coordinate invariance, we have to use non local position variables. It turns
out that free particles move on geodesics and momentum dependent translations
of Relative Locality are replaced with momentum dependent geodesic deviations.
| [
{
"created": "Thu, 9 Jan 2014 16:23:28 GMT",
"version": "v1"
}
] | 2014-03-05 | [
[
"Cianfrani",
"Francesco",
""
],
[
"Kowalski-Glikman",
"Jerzy",
""
],
[
"Rosati",
"Giacomo",
""
]
] | We construct a theory of particles moving in curved both momentum space and spacetime, being a generalization of Relative Locality. We find that in order to construct such theory, with desired symmetries, including the general coordinate invariance, we have to use non local position variables. It turns out that free particles move on geodesics and momentum dependent translations of Relative Locality are replaced with momentum dependent geodesic deviations. |
gr-qc/0010100 | Janna Levin | Janna Levin | The fate of chaotic binaries | New figures | Phys.Rev. D67 (2003) 044013 | 10.1103/PhysRevD.67.044013 | null | gr-qc astro-ph | null | A typical stellar mass black hole with a lighter companion is shown to
succumb to a chaotic precession of the orbital plane. As a result, the optimal
candidates for the direct detection of gravitational waves by Earth based
interferometers can show irregular modulation of the waveform during the last
orbits before plunge. The precession and the subsequent modulation of the
gravitational radiation depends on the mass ratio, eccentricity, and spins. The
smaller the mass of the companion, the more prominent the effect of the
precession. The most important parameters are the spin magnitudes and
misalignments. If the spins are small and nearly aligned with the orbital
angular momentum, then there will be no chaotic precession while increasing
both the spin magnitudes and misalignments increases the erratic precession. A
large eccentricity can be induced by large, misaligned spins but does not seem
to be required for chaos. An irregular precession of the orbital plane will
generate irregularities in the gravitational wave frequency but may have a
lesser effect on the total number of cycles observed.
| [
{
"created": "Thu, 26 Oct 2000 23:49:39 GMT",
"version": "v1"
},
{
"created": "Tue, 26 Mar 2002 18:41:52 GMT",
"version": "v2"
},
{
"created": "Tue, 26 Mar 2002 21:54:40 GMT",
"version": "v3"
}
] | 2009-10-31 | [
[
"Levin",
"Janna",
""
]
] | A typical stellar mass black hole with a lighter companion is shown to succumb to a chaotic precession of the orbital plane. As a result, the optimal candidates for the direct detection of gravitational waves by Earth based interferometers can show irregular modulation of the waveform during the last orbits before plunge. The precession and the subsequent modulation of the gravitational radiation depends on the mass ratio, eccentricity, and spins. The smaller the mass of the companion, the more prominent the effect of the precession. The most important parameters are the spin magnitudes and misalignments. If the spins are small and nearly aligned with the orbital angular momentum, then there will be no chaotic precession while increasing both the spin magnitudes and misalignments increases the erratic precession. A large eccentricity can be induced by large, misaligned spins but does not seem to be required for chaos. An irregular precession of the orbital plane will generate irregularities in the gravitational wave frequency but may have a lesser effect on the total number of cycles observed. |
gr-qc/0012022 | Hiroko Koyama | Hiroko Koyama and Akira Tomimatsu | Asymptotic power-law tails of massive scalar fields in
Reissner-Nordstr\"{o}m background | 18 pages, 1 figure, accepted for publication in Physical Review D | Phys.Rev. D63 (2001) 064032 | 10.1103/PhysRevD.63.064032 | DPNU-00-41 | gr-qc | null | We investigate dominant late-time tail behaviors of massive scalar fields in
nearly extreme Reissner-Nordstr\"{o}m background. It is shown that the
oscillatory tail of the scalar fields has the decay rate of $t^{-5/6}$ at
asymptotically late times. The physical mechanism by which the asymptotic
$t^{-5/6}$ tail yields and the relation between the field mass and the time
scale when the tail begins to dominate, are discussed in terms of resonance
backscattering due to spacetime curvature.
| [
{
"created": "Wed, 6 Dec 2000 04:22:40 GMT",
"version": "v1"
},
{
"created": "Fri, 22 Dec 2000 03:19:36 GMT",
"version": "v2"
}
] | 2007-10-02 | [
[
"Koyama",
"Hiroko",
""
],
[
"Tomimatsu",
"Akira",
""
]
] | We investigate dominant late-time tail behaviors of massive scalar fields in nearly extreme Reissner-Nordstr\"{o}m background. It is shown that the oscillatory tail of the scalar fields has the decay rate of $t^{-5/6}$ at asymptotically late times. The physical mechanism by which the asymptotic $t^{-5/6}$ tail yields and the relation between the field mass and the time scale when the tail begins to dominate, are discussed in terms of resonance backscattering due to spacetime curvature. |
1405.5745 | Mustapha Azreg-A\"inou | Mustapha Azreg-A\"inou, Glauber T. Marques, Manuel E. Rodrigues | Phantom black holes and critical phenomena | 13 pages, 9 figures. Minor revision. To appear in JCAP | JCAP07 (2014) 036 | 10.1088/1475-7516/2014/07/036 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the two classes cosh and sinh of normal and phantom black holes
of Einstein-Maxwell-dilaton theory. The thermodynamics of these holes is
characterized by heat capacities that may have both signs depending on the
parameters of the theory. Leaving aside the normal Reissner-Nordstr\"om black
hole, it is shown that only some phantom black holes of both classes exhibit
critical phenomena. The two classes share a nonextremality, but special,
critical point where the transition is continuous and the heat capacity, at
constant charge, changes sign with an infinite discontinuity. This point yields
a classification scheme for critical points. It is concluded that the two
unstable and stable phases coexist on one side of the criticality state and
disappear on the other side, that is, there is no configuration where only one
phase exists. The sinh class has an extremality critical point where the
entropy diverges. The transition from extremality to nonextremality with the
charge held constant is accompanied by a loss of mass and an increase in the
temperature. A special case of this transition is when the hole is isolated
(microcanonical ensemble), it will evolve by emission of energy, which results
in a decrease of its mass, to the final state of minimum mass and vanishing
heat capacity. The Ehrenfest scheme of classification is inaccurate in this
case but the generalized one due to Hilfer leads to conclude that the
transition is of order less than unity. Fluctuations near criticality are also
investigated.
| [
{
"created": "Thu, 22 May 2014 13:14:24 GMT",
"version": "v1"
},
{
"created": "Tue, 24 Jun 2014 11:03:56 GMT",
"version": "v2"
}
] | 2014-07-18 | [
[
"Azreg-Aïnou",
"Mustapha",
""
],
[
"Marques",
"Glauber T.",
""
],
[
"Rodrigues",
"Manuel E.",
""
]
] | We consider the two classes cosh and sinh of normal and phantom black holes of Einstein-Maxwell-dilaton theory. The thermodynamics of these holes is characterized by heat capacities that may have both signs depending on the parameters of the theory. Leaving aside the normal Reissner-Nordstr\"om black hole, it is shown that only some phantom black holes of both classes exhibit critical phenomena. The two classes share a nonextremality, but special, critical point where the transition is continuous and the heat capacity, at constant charge, changes sign with an infinite discontinuity. This point yields a classification scheme for critical points. It is concluded that the two unstable and stable phases coexist on one side of the criticality state and disappear on the other side, that is, there is no configuration where only one phase exists. The sinh class has an extremality critical point where the entropy diverges. The transition from extremality to nonextremality with the charge held constant is accompanied by a loss of mass and an increase in the temperature. A special case of this transition is when the hole is isolated (microcanonical ensemble), it will evolve by emission of energy, which results in a decrease of its mass, to the final state of minimum mass and vanishing heat capacity. The Ehrenfest scheme of classification is inaccurate in this case but the generalized one due to Hilfer leads to conclude that the transition is of order less than unity. Fluctuations near criticality are also investigated. |
1903.01998 | Hongyu Shen | Hongyu Shen, E. A. Huerta, Eamonn O'Shea, Prayush Kumar, Zhizhen Zhao | Statistically-informed deep learning for gravitational wave parameter
estimation | v4: 13 pages, 6 figures, First application of Neural Networks for
gravitational wave parameter posterior estimation across multiple events with
single training | Machine Learning: Science and Technology, Volume 3, Number 1, Year
2022 | 10.1088/2632-2153/ac3843 | null | gr-qc astro-ph.HE cs.AI cs.LG stat.ML | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We introduce deep learning models to estimate the masses of the binary
components of black hole mergers, $(m_1,m_2)$, and three astrophysical
properties of the post-merger compact remnant, namely, the final spin, $a_f$,
and the frequency and damping time of the ringdown oscillations of the
fundamental $\ell=m=2$ bar mode, $(\omega_R, \omega_I)$. Our neural networks
combine a modified $\texttt{WaveNet}$ architecture with contrastive learning
and normalizing flow. We validate these models against a Gaussian conjugate
prior family whose posterior distribution is described by a closed analytical
expression. Upon confirming that our models produce statistically consistent
results, we used them to estimate the astrophysical parameters $(m_1,m_2, a_f,
\omega_R, \omega_I)$ of five binary black holes: $\texttt{GW150914},
\texttt{GW170104}, \texttt{GW170814}, \texttt{GW190521}$ and
$\texttt{GW190630}$. We use $\texttt{PyCBC Inference}$ to directly compare
traditional Bayesian methodologies for parameter estimation with our
deep-learning-based posterior distributions. Our results show that our neural
network models predict posterior distributions that encode physical
correlations, and that our data-driven median results and 90$\%$ confidence
intervals are similar to those produced with gravitational wave Bayesian
analyses. This methodology requires a single V100 $\texttt{NVIDIA}$ GPU to
produce median values and posterior distributions within two milliseconds for
each event. This neural network, and a tutorial for its use, are available at
the $\texttt{Data and Learning Hub for Science}$.
| [
{
"created": "Tue, 5 Mar 2019 19:00:02 GMT",
"version": "v1"
},
{
"created": "Sun, 15 Sep 2019 17:39:55 GMT",
"version": "v2"
},
{
"created": "Wed, 10 Mar 2021 01:48:35 GMT",
"version": "v3"
},
{
"created": "Sun, 19 Dec 2021 06:45:22 GMT",
"version": "v4"
}
] | 2021-12-21 | [
[
"Shen",
"Hongyu",
""
],
[
"Huerta",
"E. A.",
""
],
[
"O'Shea",
"Eamonn",
""
],
[
"Kumar",
"Prayush",
""
],
[
"Zhao",
"Zhizhen",
""
]
] | We introduce deep learning models to estimate the masses of the binary components of black hole mergers, $(m_1,m_2)$, and three astrophysical properties of the post-merger compact remnant, namely, the final spin, $a_f$, and the frequency and damping time of the ringdown oscillations of the fundamental $\ell=m=2$ bar mode, $(\omega_R, \omega_I)$. Our neural networks combine a modified $\texttt{WaveNet}$ architecture with contrastive learning and normalizing flow. We validate these models against a Gaussian conjugate prior family whose posterior distribution is described by a closed analytical expression. Upon confirming that our models produce statistically consistent results, we used them to estimate the astrophysical parameters $(m_1,m_2, a_f, \omega_R, \omega_I)$ of five binary black holes: $\texttt{GW150914}, \texttt{GW170104}, \texttt{GW170814}, \texttt{GW190521}$ and $\texttt{GW190630}$. We use $\texttt{PyCBC Inference}$ to directly compare traditional Bayesian methodologies for parameter estimation with our deep-learning-based posterior distributions. Our results show that our neural network models predict posterior distributions that encode physical correlations, and that our data-driven median results and 90$\%$ confidence intervals are similar to those produced with gravitational wave Bayesian analyses. This methodology requires a single V100 $\texttt{NVIDIA}$ GPU to produce median values and posterior distributions within two milliseconds for each event. This neural network, and a tutorial for its use, are available at the $\texttt{Data and Learning Hub for Science}$. |
0809.5040 | Mamdouh Wanas | M. I. Wanas | Dark Energy: A Missing Physical Ingredient | 9 pages, LaTeX- file. Penary talk presented at the sixth conference
on "Nuclear and Particle Physics", held in Luxor, Egypt, 17-21 November 2007 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recent observation of supernovae type Ia show clearly that there is a large
scale repulsive force in the Universe. Neither of the four known fundamental
interactions can account for this repulsive force. Gravity is known to be the
interaction responsible for the large scale structure and evolution of the
Universe. The problem with gravity is that it gives rise to a force which is
attractive only. Gravity theories, including General Relativity, deals with
gravity as an attractive force. Although this is consistent with our experience
in the solar system and other similar astrophysical systems, gravity theories
fail to account for SN type Ia observation. So, we are in a real problem
concerning the interpretation of these observation. This problem is only ten
years old. In order to go out of this problematic situation, scientists have
suggested the existence of a type of energy in the Universe that is responsible
for the above mentioned repulsive force. They have given this type of energy
the exotic term {\it "Dark Energy"}. Although this type of energy forms more
than two thirds of the energetic contents of our Universe, its reasonable
nature is missing in all gravity theories.
The aim of the present work is to review the present status of the problem of
dark energy. Also, to suggest a new geometric solution for this problem.
| [
{
"created": "Mon, 29 Sep 2008 18:45:43 GMT",
"version": "v1"
}
] | 2008-09-30 | [
[
"Wanas",
"M. I.",
""
]
] | Recent observation of supernovae type Ia show clearly that there is a large scale repulsive force in the Universe. Neither of the four known fundamental interactions can account for this repulsive force. Gravity is known to be the interaction responsible for the large scale structure and evolution of the Universe. The problem with gravity is that it gives rise to a force which is attractive only. Gravity theories, including General Relativity, deals with gravity as an attractive force. Although this is consistent with our experience in the solar system and other similar astrophysical systems, gravity theories fail to account for SN type Ia observation. So, we are in a real problem concerning the interpretation of these observation. This problem is only ten years old. In order to go out of this problematic situation, scientists have suggested the existence of a type of energy in the Universe that is responsible for the above mentioned repulsive force. They have given this type of energy the exotic term {\it "Dark Energy"}. Although this type of energy forms more than two thirds of the energetic contents of our Universe, its reasonable nature is missing in all gravity theories. The aim of the present work is to review the present status of the problem of dark energy. Also, to suggest a new geometric solution for this problem. |
1009.5100 | Valentin Bonzom | Valentin Bonzom | G\'eom\'etrie quantique dans les mousses de spins : de la th\'eorie
topologique BF vers la relativit\'e g\'en\'erale | PhD. Thesis 2010, in French, Centre de Physique Th\'eorique | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Loop quantum gravity has provided us with a canonical framework especially
devised for background independent and diffeomorphism invariant gauge field
theories. In this quantization the fundamental excitations are called spin
network states, and in the context of general relativity, they give a meaning
to quantum geometry. Spin foams are a sort of path integral for spin network
states, supposed to enable the computations of transition amplitudes between
these states. The spin foam quantization has proved very efficient for
topological field theories, like 2d Yang-Mills, 3d gravity or BF theories.
Different models have also been proposed for 4-dimensional quantum gravity. In
this PhD manuscript, I discuss several methods to study spin foam models. In
particular, I present some recurrence relations on spin foam amplitudes, which
generically encode classical symmetries at the quantum level, and are likely to
help fill the gap with the Hamiltonian constraints. These relations can be
naturally interpreted in terms of elementary deformations of discrete geometric
structures, like simplicial geometries. Another interesting method consists in
exploring the way spin foam models can be written as path integrals for systems
of geometries on a lattice, taking inspiration from topological models and
Regge calculus. This leads to a very geometric view on spin foams, and gives
classical action principles which are studied in details.
| [
{
"created": "Sun, 26 Sep 2010 15:00:25 GMT",
"version": "v1"
}
] | 2010-09-28 | [
[
"Bonzom",
"Valentin",
""
]
] | Loop quantum gravity has provided us with a canonical framework especially devised for background independent and diffeomorphism invariant gauge field theories. In this quantization the fundamental excitations are called spin network states, and in the context of general relativity, they give a meaning to quantum geometry. Spin foams are a sort of path integral for spin network states, supposed to enable the computations of transition amplitudes between these states. The spin foam quantization has proved very efficient for topological field theories, like 2d Yang-Mills, 3d gravity or BF theories. Different models have also been proposed for 4-dimensional quantum gravity. In this PhD manuscript, I discuss several methods to study spin foam models. In particular, I present some recurrence relations on spin foam amplitudes, which generically encode classical symmetries at the quantum level, and are likely to help fill the gap with the Hamiltonian constraints. These relations can be naturally interpreted in terms of elementary deformations of discrete geometric structures, like simplicial geometries. Another interesting method consists in exploring the way spin foam models can be written as path integrals for systems of geometries on a lattice, taking inspiration from topological models and Regge calculus. This leads to a very geometric view on spin foams, and gives classical action principles which are studied in details. |
2005.01418 | Takahisa Igata | Takahisa Igata | Particle dynamics in the Newtonian potential sourced by a homogeneous
circular ring | 18 pages, 1 figure; v2: minor revision; v3: published version | Phys. Rev. D 101, 124064 (2020) | 10.1103/PhysRevD.101.124064 | KEK-Cosmo-253, KEK-TH-2213 | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Newtonian gravitational potential sourced by a homogeneous circular ring in
arbitrary dimensional Euclidean space takes a simple form if the spatial
dimension is even. In contrast, if the spatial dimension is odd, it is given in
a form that includes complete elliptic integrals. In this paper, we analyze the
dynamics of a freely falling massive particle in its Newtonian potential.
Focusing on circular orbits on the symmetric plane where the ring is placed, we
observe that they are unstable in 4D space and above, while they are stable in
3D space. The sequence of stable circular orbits disappears at $1.6095\cdots$
times the radius of the ring, which corresponds to the innermost stable
circular orbit (ISCO). On the axis of symmetry of the ring, there are no
circular orbits in 3D space but more than in 4D space. In particular, the
circular orbits are stable between the ISCO and infinity in 4D space and
between the ISCO and the outermost stable circular orbit in 5D space. There
exist no stable circular orbits in 6D space and above.
| [
{
"created": "Mon, 4 May 2020 12:17:29 GMT",
"version": "v1"
},
{
"created": "Tue, 16 Jun 2020 02:34:59 GMT",
"version": "v2"
},
{
"created": "Mon, 29 Jun 2020 15:08:36 GMT",
"version": "v3"
}
] | 2020-06-30 | [
[
"Igata",
"Takahisa",
""
]
] | Newtonian gravitational potential sourced by a homogeneous circular ring in arbitrary dimensional Euclidean space takes a simple form if the spatial dimension is even. In contrast, if the spatial dimension is odd, it is given in a form that includes complete elliptic integrals. In this paper, we analyze the dynamics of a freely falling massive particle in its Newtonian potential. Focusing on circular orbits on the symmetric plane where the ring is placed, we observe that they are unstable in 4D space and above, while they are stable in 3D space. The sequence of stable circular orbits disappears at $1.6095\cdots$ times the radius of the ring, which corresponds to the innermost stable circular orbit (ISCO). On the axis of symmetry of the ring, there are no circular orbits in 3D space but more than in 4D space. In particular, the circular orbits are stable between the ISCO and infinity in 4D space and between the ISCO and the outermost stable circular orbit in 5D space. There exist no stable circular orbits in 6D space and above. |
gr-qc/0611128 | Nicolas Yunes | Nicolas Yunes (Penn State) | Frankenstein's Glue: Transition functions for approximate solutions | 23 pages, 5 figures. Replaced with accepted version. Major
improvements to text, with added examples | Class.Quant.Grav.24:4313-4336,2007 | 10.1088/0264-9381/24/17/004 | IGPG-06/11-2 | gr-qc | null | Approximations are commonly employed to find approximate solutions to the
Einstein equations. These solutions, however, are usually only valid in some
specific spacetime region. A global solution can be constructed by gluing
approximate solutions together, but this procedure is difficult because
discontinuities can arise, leading to large violations of the Einstein
equations. In this paper, we provide an attempt to formalize this gluing scheme
by studying transition functions that join approximate solutions together. In
particular, we propose certain sufficient conditions on these functions and
proof that these conditions guarantee that the joined solution still satisfies
the Einstein equations to the same order as the approximate ones. An example is
also provided for a binary system of non-spinning black holes, where the
approximate solutions are taken to be given by a post-Newtonian expansion and a
perturbed Schwarzschild solution. For this specific case, we show that if the
transition functions satisfy the proposed conditions, the joined solution does
not contain any violations to the Einstein equations larger than those already
inherent in the approximations. We further show that if these functions violate
the proposed conditions, then the matter content of the spacetime is modified
by the introduction of a matter-shell, whose stress-energy tensor depends on
derivatives of these functions.
| [
{
"created": "Thu, 23 Nov 2006 20:56:59 GMT",
"version": "v1"
},
{
"created": "Fri, 17 Aug 2007 13:02:04 GMT",
"version": "v2"
}
] | 2010-05-12 | [
[
"Yunes",
"Nicolas",
"",
"Penn State"
]
] | Approximations are commonly employed to find approximate solutions to the Einstein equations. These solutions, however, are usually only valid in some specific spacetime region. A global solution can be constructed by gluing approximate solutions together, but this procedure is difficult because discontinuities can arise, leading to large violations of the Einstein equations. In this paper, we provide an attempt to formalize this gluing scheme by studying transition functions that join approximate solutions together. In particular, we propose certain sufficient conditions on these functions and proof that these conditions guarantee that the joined solution still satisfies the Einstein equations to the same order as the approximate ones. An example is also provided for a binary system of non-spinning black holes, where the approximate solutions are taken to be given by a post-Newtonian expansion and a perturbed Schwarzschild solution. For this specific case, we show that if the transition functions satisfy the proposed conditions, the joined solution does not contain any violations to the Einstein equations larger than those already inherent in the approximations. We further show that if these functions violate the proposed conditions, then the matter content of the spacetime is modified by the introduction of a matter-shell, whose stress-energy tensor depends on derivatives of these functions. |
gr-qc/9309015 | Wai Suen | Edward Seidel and Wai-Mo Suen | Formation of Solitonic Stars Through Gravitational Cooling | 14 pages, 93-5 | Phys.Rev.Lett.72:2516-2519,1994 | 10.1103/PhysRevLett.72.2516 | null | gr-qc | null | We studied the formation of compact bosonic objects through a dissipationless
cooling mechanism. Implications of the existence of this mechanism are
discussed, including the abundance of bosonic stars in the universe, and the
possibility of ruling out the axion as a dark matter candidate.
| [
{
"created": "Tue, 14 Sep 1993 23:45:25 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Seidel",
"Edward",
""
],
[
"Suen",
"Wai-Mo",
""
]
] | We studied the formation of compact bosonic objects through a dissipationless cooling mechanism. Implications of the existence of this mechanism are discussed, including the abundance of bosonic stars in the universe, and the possibility of ruling out the axion as a dark matter candidate. |
gr-qc/9904026 | David I. Santiago | Ronald J. Adler, David I. Santiago | On Gravity and the Uncertainty Principle | Gravity Research Foundation essay. 14 pages Minor typos were
corrected | Mod.Phys.Lett. A14 (1999) 1371 | 10.1142/S0217732399001462 | null | gr-qc hep-th quant-ph | null | Heisenberg showed in the early days of quantum theory that the uncertainty
principle follows as a direct consequence of the quantization of
electromagnetic radiation in the form of photons. As we show here the
gravitational interaction of the photon and the particle being observed
modifies the uncertainty principle with an additional term. From the modified
or gravitational uncertainty principle it follows that there is an absolute
minimum uncertainty in the position of any particle, of order of the Planck
length. A modified uncertainty relation of this form is a standard result of
superstring theory, but the derivation given here is based on simpler and
rather general considerations with either Newtonian gravitational theory or
general relativity theory.
| [
{
"created": "Mon, 12 Apr 1999 03:33:37 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Apr 1999 01:10:06 GMT",
"version": "v2"
}
] | 2016-08-31 | [
[
"Adler",
"Ronald J.",
""
],
[
"Santiago",
"David I.",
""
]
] | Heisenberg showed in the early days of quantum theory that the uncertainty principle follows as a direct consequence of the quantization of electromagnetic radiation in the form of photons. As we show here the gravitational interaction of the photon and the particle being observed modifies the uncertainty principle with an additional term. From the modified or gravitational uncertainty principle it follows that there is an absolute minimum uncertainty in the position of any particle, of order of the Planck length. A modified uncertainty relation of this form is a standard result of superstring theory, but the derivation given here is based on simpler and rather general considerations with either Newtonian gravitational theory or general relativity theory. |
gr-qc/0607094 | Richard Woodard | T. Prokopec (U. Utrecht), N. C. Tsamis (U. Crete) and R. P. Woodard
(U. Florida) | Two Loop Scalar Bilinears for Inflationary SQED | 43 pages, LaTeX 2epsilon, 5 figures (using axodraw.sty) Version 2 has
updated references and important corrections to Tables 3-5 and to eqns
(139-141), (145-146), (153-155), (158) and (160) | Class.Quant.Grav.24:201-230,2007 | 10.1088/0264-9381/24/1/011 | UFIFT-QG-06-07 | gr-qc astro-ph hep-ph | null | We evaluate the one and two loop contributions to the expectation values of
two coincident and gauge invariant scalar bilinears in the theory of massless,
minimally coupled scalar quantum electrodynamics on a locally de Sitter
background. One of these bilinears is the product of two covariantly
differentiated scalars, the other is the product of two undifferentiated
scalars. The computations are done using dimensional regularization and the
Schwinger-Keldysh formalism. Our results are in perfect agreement with the
stochastic predictions at this order.
| [
{
"created": "Sat, 22 Jul 2006 15:00:25 GMT",
"version": "v1"
},
{
"created": "Fri, 15 Feb 2008 23:56:05 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Prokopec",
"T.",
"",
"U. Utrecht"
],
[
"Tsamis",
"N. C.",
"",
"U. Crete"
],
[
"Woodard",
"R. P.",
"",
"U. Florida"
]
] | We evaluate the one and two loop contributions to the expectation values of two coincident and gauge invariant scalar bilinears in the theory of massless, minimally coupled scalar quantum electrodynamics on a locally de Sitter background. One of these bilinears is the product of two covariantly differentiated scalars, the other is the product of two undifferentiated scalars. The computations are done using dimensional regularization and the Schwinger-Keldysh formalism. Our results are in perfect agreement with the stochastic predictions at this order. |
1508.05010 | Anja Marunovic | Anja Marunovi\'c and Tomislav Prokopec | Topological inflation with graceful exit | 11 pages, 7 figures; matches published version | null | 10.1088/1475-7516/2016/04/052 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate a class of models of topological inflation in which a
super-Hubble-sized global monopole seeds inflation. These models are attractive
since inflation starts from rather generic initial conditions, but their not so
attractive feature is that, unless symmetry is again restored, inflation never
ends. In this work we show that, in presence of another nonminimally coupled
scalar field, that is both quadratically and quartically coupled to the Ricci
scalar, inflation naturally ends, representing an elegant solution to the
graceful exit problem of topological inflation. While the monopole core grows
during inflation, the growth stops after inflation, such that the monopole
eventually enters the Hubble radius, and shrinks to its Minkowski space size,
rendering it immaterial for the subsequent Universe's dynamics. Furthermore, we
find that our model can produce cosmological perturbations that source CMB
temperature fluctuations and seed large scale structure statistically
consistent (within one standard deviation) with all available data. In
particular, for small and (in our convention) negative nonminimal couplings,
the scalar spectral index can be as large as $n_s\simeq 0.955$, which is about
one standard deviation lower than the central value quoted by the most recent
Planck Collaboration.
| [
{
"created": "Thu, 20 Aug 2015 15:41:54 GMT",
"version": "v1"
},
{
"created": "Tue, 26 Apr 2016 09:43:57 GMT",
"version": "v2"
}
] | 2016-05-04 | [
[
"Marunović",
"Anja",
""
],
[
"Prokopec",
"Tomislav",
""
]
] | We investigate a class of models of topological inflation in which a super-Hubble-sized global monopole seeds inflation. These models are attractive since inflation starts from rather generic initial conditions, but their not so attractive feature is that, unless symmetry is again restored, inflation never ends. In this work we show that, in presence of another nonminimally coupled scalar field, that is both quadratically and quartically coupled to the Ricci scalar, inflation naturally ends, representing an elegant solution to the graceful exit problem of topological inflation. While the monopole core grows during inflation, the growth stops after inflation, such that the monopole eventually enters the Hubble radius, and shrinks to its Minkowski space size, rendering it immaterial for the subsequent Universe's dynamics. Furthermore, we find that our model can produce cosmological perturbations that source CMB temperature fluctuations and seed large scale structure statistically consistent (within one standard deviation) with all available data. In particular, for small and (in our convention) negative nonminimal couplings, the scalar spectral index can be as large as $n_s\simeq 0.955$, which is about one standard deviation lower than the central value quoted by the most recent Planck Collaboration. |
gr-qc/9708006 | Boris N. Frolov | O. V. Babourova, B. N. Frolov (Department of Mathematics, Moscow State
Pedagogical University) | The variational theory of the perfect dilaton-spin fluid in a
Weyl-Cartan space | 25 July 1997. - 10 p. The variational procedure is improved, the
results being unchanged | Mod.Phys.Lett. A12 (1997) 2943-2950 | 10.1142/S021773239700306X | null | gr-qc | null | The variational theory of the perfect fluid with intrinsic spin and dilatonic
charge (dilaton-spin fluid) is developed. The spin tensor obeys the classical
Frenkel condition. The Lagrangian density of such fluid is stated, and the
equations of motion of the fluid, the Weyssenhoff-type evolution equation of
the spin tensor and the conservation law of the dilatonic charge are derived.
The expressions of the matter currents of the fluid (the canonical
energy-momentum 3-form, the metric stress-energy 4-form and the dilaton-spin
momentum 3-form) are obtained.
| [
{
"created": "Mon, 4 Aug 1997 20:06:45 GMT",
"version": "v1"
},
{
"created": "Mon, 26 Jan 1998 23:56:41 GMT",
"version": "v2"
}
] | 2009-10-30 | [
[
"Babourova",
"O. V.",
"",
"Department of Mathematics, Moscow State\n Pedagogical University"
],
[
"Frolov",
"B. N.",
"",
"Department of Mathematics, Moscow State\n Pedagogical University"
]
] | The variational theory of the perfect fluid with intrinsic spin and dilatonic charge (dilaton-spin fluid) is developed. The spin tensor obeys the classical Frenkel condition. The Lagrangian density of such fluid is stated, and the equations of motion of the fluid, the Weyssenhoff-type evolution equation of the spin tensor and the conservation law of the dilatonic charge are derived. The expressions of the matter currents of the fluid (the canonical energy-momentum 3-form, the metric stress-energy 4-form and the dilaton-spin momentum 3-form) are obtained. |
1001.4697 | Priscilla Canizares | Priscilla Canizares and Carlos F. Sopuerta (ICE, CSIC-IEEC) | Modelling Extreme-Mass-Ratio Inspirals using Pseudospectral Methods | 3 pages. To appear in Proceedings of the Twelfth Marcel Grossmann
Meeting on General Relativity, edited by Thibault Damour, Robert T Jantzen
and Remo Ruffini, World Scientific, Singapore, 2010 | null | null | null | gr-qc astro-ph.GA astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We introduce a new time-domain method for computing the self-force acting on
a scalar particle in a Schwarzschild geometry. The principal feature of our
method consists in the division of the spatial domain into several subdomains
and locating the particle at the interface betweem two them. In this way, we
avoid the need of resolving a small length scale associated with the presence
of a particle in the computational domain and, at the same time, we avoid
numerical problems due to the low differentiability of solutions of equations
with point-like singular behaviour.
| [
{
"created": "Tue, 26 Jan 2010 14:18:33 GMT",
"version": "v1"
}
] | 2010-01-27 | [
[
"Canizares",
"Priscilla",
"",
"ICE, CSIC-IEEC"
],
[
"Sopuerta",
"Carlos F.",
"",
"ICE, CSIC-IEEC"
]
] | We introduce a new time-domain method for computing the self-force acting on a scalar particle in a Schwarzschild geometry. The principal feature of our method consists in the division of the spatial domain into several subdomains and locating the particle at the interface betweem two them. In this way, we avoid the need of resolving a small length scale associated with the presence of a particle in the computational domain and, at the same time, we avoid numerical problems due to the low differentiability of solutions of equations with point-like singular behaviour. |
gr-qc/0309096 | Stephane Fay | Stephane Fay | Isotropisation of Bianchi class A models with curvature for a minimally
coupled scalar tensor theory | 20 pages | Class.Quant.Grav.20:1363-1378,2003 | 10.1088/0264-9381/20/7/308 | null | gr-qc | null | We look for necessary isotropisation conditions of Bianchi class $A$ models
with curvature in presence of a massive and minimally coupled scalar field when
a function $\ell$ of the scalar field tends to a constant, diverges
monotonically or with sufficiently small oscillations. Isotropisation leads the
metric functions to tend to a power or exponential law of the proper time $t$
and the potential respectively to vanish as $t^{-2}$ or to a constant.
Moreover, isotropisation always requires late time accelerated expansion and
flatness of the Universe.
| [
{
"created": "Fri, 19 Sep 2003 12:29:40 GMT",
"version": "v1"
}
] | 2009-01-07 | [
[
"Fay",
"Stephane",
""
]
] | We look for necessary isotropisation conditions of Bianchi class $A$ models with curvature in presence of a massive and minimally coupled scalar field when a function $\ell$ of the scalar field tends to a constant, diverges monotonically or with sufficiently small oscillations. Isotropisation leads the metric functions to tend to a power or exponential law of the proper time $t$ and the potential respectively to vanish as $t^{-2}$ or to a constant. Moreover, isotropisation always requires late time accelerated expansion and flatness of the Universe. |
gr-qc/0601135 | Rod Aros Mr. | Rodrigo Aros and Mauricio Contreras | Torsion induces Gravity | 4 pages, RevTex | Phys.Rev. D73 (2006) 087501 | 10.1103/PhysRevD.73.087501 | GACG/02/2006 | gr-qc | null | In this work the Poincare-Chern Simons and Anti de Sitter Chern Simons
gravities are studied. For both a solution that can be casted as a black hole
with manifest torsion is found. Those solutions resemble Schwarzschild and
Schwarzschild-AdS solutions respectively.
| [
{
"created": "Mon, 30 Jan 2006 19:03:06 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Aros",
"Rodrigo",
""
],
[
"Contreras",
"Mauricio",
""
]
] | In this work the Poincare-Chern Simons and Anti de Sitter Chern Simons gravities are studied. For both a solution that can be casted as a black hole with manifest torsion is found. Those solutions resemble Schwarzschild and Schwarzschild-AdS solutions respectively. |
gr-qc/9701045 | Esposito Giampiero | Giampiero Esposito and Cosimo Stornaiolo | Multimomentum Maps on Null Hypersurfaces | 13 pages, plain Tex | Nuovo Cim. B112 (1997) 1395-1403 | null | DSF preprint 97/4 | gr-qc | null | This paper studies the application of multimomentum maps to the constraint
analysis of general relativity on null hypersurfaces. It is shown that, unlike
the case of spacelike hypersurfaces, some constraints which are second class in
the Hamiltonian formalism turn out to contribute to the multimomentum map. To
recover the whole set of secondary constraints found in the Hamiltonian
formalism, it is necessary to combine the multimomentum map with those
particular Euler-Lagrange equations which are not of evolutionary type. The
analysis is performed on the outgoing null cone only.
| [
{
"created": "Mon, 20 Jan 1997 18:10:03 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Esposito",
"Giampiero",
""
],
[
"Stornaiolo",
"Cosimo",
""
]
] | This paper studies the application of multimomentum maps to the constraint analysis of general relativity on null hypersurfaces. It is shown that, unlike the case of spacelike hypersurfaces, some constraints which are second class in the Hamiltonian formalism turn out to contribute to the multimomentum map. To recover the whole set of secondary constraints found in the Hamiltonian formalism, it is necessary to combine the multimomentum map with those particular Euler-Lagrange equations which are not of evolutionary type. The analysis is performed on the outgoing null cone only. |
gr-qc/0210106 | Robert D. Klauber | Robert D. Klauber | Analysis of the Anomalous Brillet and Hall Experimental Result | 19 pages, including 5 figures, 3 appendices, and references | Found.Phys.Lett. 17 (2004) 125-147 | null | null | gr-qc | null | The persistent, second order, anomalous signal found in the Brillet and Hall
experiment is derived by applying 4D differential geometry in the rotating
earth frame. By incorporating the off diagonal time-space components of the
rotating frame metric directly into the analysis, rather than arbitrarily
transforming them away, one finds a signal dependence on the surface speed of
the earth due to rotation about its axis. This leads to a Brillet-Hall signal
prediction in remarkably close agreement with experiment. No signal is
predicted from the speed of the earth in solar or galactic orbit, as the
associated metric for gravitational orbit has no off diagonal component. To
corroborate this result, a repetition by other experimentalists of the
Brillet-Hall experiment, in which the test apparatus turns with respect to the
earth surface, is urged.
| [
{
"created": "Wed, 30 Oct 2002 21:40:45 GMT",
"version": "v1"
},
{
"created": "Fri, 28 Nov 2003 21:45:00 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Klauber",
"Robert D.",
""
]
] | The persistent, second order, anomalous signal found in the Brillet and Hall experiment is derived by applying 4D differential geometry in the rotating earth frame. By incorporating the off diagonal time-space components of the rotating frame metric directly into the analysis, rather than arbitrarily transforming them away, one finds a signal dependence on the surface speed of the earth due to rotation about its axis. This leads to a Brillet-Hall signal prediction in remarkably close agreement with experiment. No signal is predicted from the speed of the earth in solar or galactic orbit, as the associated metric for gravitational orbit has no off diagonal component. To corroborate this result, a repetition by other experimentalists of the Brillet-Hall experiment, in which the test apparatus turns with respect to the earth surface, is urged. |
2307.00330 | Fengge Zhang | Fengge Zhang, Jia-Xi Feng, Xian Gao | Scalar induced gravitational waves in symmetric teleparallel gravity
with a parity-violating term | 32 pages,2 figures | Physical Review D,2023 | 10.1103/PhysRevD.108.063513 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational waves (GWs) are useful to test gravitational theories and to
probe the physics in the early universe. In this paper, we investigate the
scalar induced gravitational waves (SIGWs) in symmetric teleparallel gravity
with a parity-violating term. The presence of the parity-violating term leads
to the velocity birefringence effect of the SIGWs. However, after taking into
account the observational constraints on the speed of GWs, the contribution
from the parity-violating term to SIGWs is negligible. Nevertheless, the
contribution to SIGWs from the perturbations of the connection can be
significant, and results in a multipeak structure in the energy density of
SIGWs. This feature makes the symmetric teleparallel gravity distinguishable
from the general relativity.
| [
{
"created": "Sat, 1 Jul 2023 13:01:07 GMT",
"version": "v1"
},
{
"created": "Thu, 14 Sep 2023 02:50:17 GMT",
"version": "v2"
}
] | 2023-09-15 | [
[
"Zhang",
"Fengge",
""
],
[
"Feng",
"Jia-Xi",
""
],
[
"Gao",
"Xian",
""
]
] | Gravitational waves (GWs) are useful to test gravitational theories and to probe the physics in the early universe. In this paper, we investigate the scalar induced gravitational waves (SIGWs) in symmetric teleparallel gravity with a parity-violating term. The presence of the parity-violating term leads to the velocity birefringence effect of the SIGWs. However, after taking into account the observational constraints on the speed of GWs, the contribution from the parity-violating term to SIGWs is negligible. Nevertheless, the contribution to SIGWs from the perturbations of the connection can be significant, and results in a multipeak structure in the energy density of SIGWs. This feature makes the symmetric teleparallel gravity distinguishable from the general relativity. |
gr-qc/0410037 | Yoshiki Tsunesada | Yoshiki Tsunesada, Nobuyuki Kanda, Hiroyuki Nakano, Daisuke Tatsumi,
Masaki Ando, Misao Sasaki, Hideyuki Tagoshi, and Hirotaka Takahashi | On Detection of Black Hole Quasi-Normal Ringdowns: Detection Efficiency
and Waveform Parameter Determination in Matched Filtering | 10 pages, 10 figures | Phys.Rev.D71:103005,2005 | 10.1103/PhysRevD.71.103005 | OCU-PHYS-218, AP-GR-18 | gr-qc | null | Gravitational radiation from a slightly distorted black hole with ringdown
waveform is well understood in general relativity. It provides a probe for
direct observation of black holes and determination of their physical
parameters, masses and angular momenta (Kerr parameters). For ringdown searches
using data of gravitational wave detectors, matched filtering technique is
useful. In this paper, we describe studies on problems in matched filtering
analysis in realistic gravitational wave searches using observational data.
Above all, we focus on template constructions, matches or signal-to-noise
ratios (SNRs), detection probabilities for Galactic events, and accuracies in
evaluation of waveform parameters or black hole hairs. We have performed
matched filtering analysis for artificial ringdown signals which are generated
with Monte-Carlo technique and injected into the TAMA300 observational data. It
is shown that with TAMA300 sensitivity, the detection probability for Galactic
ringdown events is about 50% for black holes of masses greater than $20
M_{\odot}$ with SNR $> 10$. The accuracies in waveform parameter estimations
are found to be consistent with the template spacings, and resolutions for
black hole masses and the Kerr parameters are evaluated as a few % and $\sim 40
%$, respectively. They can be improved up to $< 0.9 %$ and $< 24 %$ for events
of ${\rm SNR} \ge 10$ by using fine-meshed template bank in the hierarchical
search strategy.
| [
{
"created": "Fri, 8 Oct 2004 06:09:49 GMT",
"version": "v1"
}
] | 2009-10-09 | [
[
"Tsunesada",
"Yoshiki",
""
],
[
"Kanda",
"Nobuyuki",
""
],
[
"Nakano",
"Hiroyuki",
""
],
[
"Tatsumi",
"Daisuke",
""
],
[
"Ando",
"Masaki",
""
],
[
"Sasaki",
"Misao",
""
],
[
"Tagoshi",
"Hideyuki",
""
],
... | Gravitational radiation from a slightly distorted black hole with ringdown waveform is well understood in general relativity. It provides a probe for direct observation of black holes and determination of their physical parameters, masses and angular momenta (Kerr parameters). For ringdown searches using data of gravitational wave detectors, matched filtering technique is useful. In this paper, we describe studies on problems in matched filtering analysis in realistic gravitational wave searches using observational data. Above all, we focus on template constructions, matches or signal-to-noise ratios (SNRs), detection probabilities for Galactic events, and accuracies in evaluation of waveform parameters or black hole hairs. We have performed matched filtering analysis for artificial ringdown signals which are generated with Monte-Carlo technique and injected into the TAMA300 observational data. It is shown that with TAMA300 sensitivity, the detection probability for Galactic ringdown events is about 50% for black holes of masses greater than $20 M_{\odot}$ with SNR $> 10$. The accuracies in waveform parameter estimations are found to be consistent with the template spacings, and resolutions for black hole masses and the Kerr parameters are evaluated as a few % and $\sim 40 %$, respectively. They can be improved up to $< 0.9 %$ and $< 24 %$ for events of ${\rm SNR} \ge 10$ by using fine-meshed template bank in the hierarchical search strategy. |
1402.6821 | Narayan Banerjee | Nandan Roy and Narayan Banerjee | Quintessence Scalar Field: A Dynamical Systems Study | 13 pages, 9 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The present work deals with a dynamical systems study of quintessence
potentials leading to the present accelerated expansion of the universe. The
principal interest is to check for late time attractors which give an
accelerated expansion for the universe. Two examples are worked out, namely the
exponential and the power-law potentials.
| [
{
"created": "Thu, 27 Feb 2014 08:28:46 GMT",
"version": "v1"
}
] | 2014-02-28 | [
[
"Roy",
"Nandan",
""
],
[
"Banerjee",
"Narayan",
""
]
] | The present work deals with a dynamical systems study of quintessence potentials leading to the present accelerated expansion of the universe. The principal interest is to check for late time attractors which give an accelerated expansion for the universe. Two examples are worked out, namely the exponential and the power-law potentials. |
0704.1173 | Xing-Hao Ye | Xing-Hao Ye, Qiang Lin | The Deviation of the Vacuum Refractive Index Induced by a Static
Gravitational Field | 5 pages, 6 figures | null | null | null | gr-qc | null | We analyzed the influence of static gravitational field on the vacuum and
proposed the concept of inhomogeneous vacuum. According to the observational
result of the light deflection in solar gravitational field as well as the
corresponding Fermat's principle in the general relativity, we derived an
analytical expression of the refractive index of vacuum in a static
gravitational field. We found that the deviation of the vacuum refractive index
is composed of two parts: one is caused by the time dilation effect, the other
is caused by the length contraction effect. As an application, we simulated the
effect of the gravitational lensing through computer programming and found that
the missing central imaging could be interpreted in a reasonable way.
| [
{
"created": "Tue, 10 Apr 2007 02:47:54 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Ye",
"Xing-Hao",
""
],
[
"Lin",
"Qiang",
""
]
] | We analyzed the influence of static gravitational field on the vacuum and proposed the concept of inhomogeneous vacuum. According to the observational result of the light deflection in solar gravitational field as well as the corresponding Fermat's principle in the general relativity, we derived an analytical expression of the refractive index of vacuum in a static gravitational field. We found that the deviation of the vacuum refractive index is composed of two parts: one is caused by the time dilation effect, the other is caused by the length contraction effect. As an application, we simulated the effect of the gravitational lensing through computer programming and found that the missing central imaging could be interpreted in a reasonable way. |
1904.11344 | Hamideh Nadi | Hamideh Nadi, Behrouz Mirza, Zeinab Sherkatghanad, Zahra Mirzaiyan | Holographic entanglement first law for d + 1 dimensional rotating
cylindrical black holes | 14 Pages, 7 figures | Nuclear Physics B 949 (2019) 114822 | 10.1016/j.nuclphysb.2019.114822 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We calculate the holographic entanglement entropy for the rotating
cylindrical black holes in $d+1$ dimensions as perturbations over $AdS_{d+1}$.
This is accomplished based on the first order variation of the area functional
in arbitrary dimensions. For these types of black holes, the angular momentum
appears at the first order of the perturbative expansion of the holographic
entanglement entropy for spacetime dimensions of d +1 $\geq$ 4. We obtain a
form of holographic entanglement first law in the presence of both energy and
angular momentum.
| [
{
"created": "Thu, 25 Apr 2019 13:58:17 GMT",
"version": "v1"
},
{
"created": "Thu, 12 Mar 2020 14:24:03 GMT",
"version": "v2"
}
] | 2020-03-13 | [
[
"Nadi",
"Hamideh",
""
],
[
"Mirza",
"Behrouz",
""
],
[
"Sherkatghanad",
"Zeinab",
""
],
[
"Mirzaiyan",
"Zahra",
""
]
] | We calculate the holographic entanglement entropy for the rotating cylindrical black holes in $d+1$ dimensions as perturbations over $AdS_{d+1}$. This is accomplished based on the first order variation of the area functional in arbitrary dimensions. For these types of black holes, the angular momentum appears at the first order of the perturbative expansion of the holographic entanglement entropy for spacetime dimensions of d +1 $\geq$ 4. We obtain a form of holographic entanglement first law in the presence of both energy and angular momentum. |
gr-qc/0103028 | Jozef Sima | Miroslav Sukenik and Jozef Sima | Information, Expansive Nondecelerative Universe, and Superstring Theory | 4 pages, LaTeX | null | null | SS-01-04 | gr-qc | null | Stemming from relationships between a number of information describing a
system and entropy content of the system it is possible to determine maximal
cosmological time. The contribution manifests a compatibility of the
superstring theory and the model of Expansive Nondecelerative Universe.
| [
{
"created": "Fri, 9 Mar 2001 10:51:42 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Sukenik",
"Miroslav",
""
],
[
"Sima",
"Jozef",
""
]
] | Stemming from relationships between a number of information describing a system and entropy content of the system it is possible to determine maximal cosmological time. The contribution manifests a compatibility of the superstring theory and the model of Expansive Nondecelerative Universe. |
2012.13020 | Roman Konoplya | R. A. Konoplya | Conformal Weyl gravity via two stages of quasinormal ringing and
late-time behavior | 7 pages, 4 figures, revtex, the version to match the published one | Phys. Rev. D 103, 044033 (2021) | 10.1103/PhysRevD.103.044033 | null | gr-qc astro-ph.HE hep-th | http://creativecommons.org/licenses/by/4.0/ | Black hole (BH) solution in the conformal Weyl gravity is a generalization of
the Schwarzschild spacetime which includes two additional constants appearing
when integrating the third order differential equations for gravitational
field. One constant looks like the effective cosmological constant providing
the de Sitter asymptotic of the solution. The other constant allows one to
describe flat rotation of galaxies without introducing of the dark matter. Here
we show that the effective "dark matter" term in the metric function
drastically changes the asymptotic behavior of the evolution of the wave
function of a scalar field: after the Schwarzschild-like ringing phase, the
ringing at another, non-Schwarzschildian, longer-lived frequency takes place
before the beginning of the exponential asymptotic tail. Thus the evolution of
the scalar field consists of the three qualitatively different stages: the
Schwarzschild-like ringing phase, the effective dark matter ringing phase and
the de Sitter phase characterized by exponential tails. The late time behavior
of the electromagnetic field is qualitatively different as well: the
exponential tails appear even in the absence of the effective de Sitter term.
| [
{
"created": "Wed, 23 Dec 2020 23:10:04 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Feb 2021 23:11:14 GMT",
"version": "v2"
}
] | 2021-02-24 | [
[
"Konoplya",
"R. A.",
""
]
] | Black hole (BH) solution in the conformal Weyl gravity is a generalization of the Schwarzschild spacetime which includes two additional constants appearing when integrating the third order differential equations for gravitational field. One constant looks like the effective cosmological constant providing the de Sitter asymptotic of the solution. The other constant allows one to describe flat rotation of galaxies without introducing of the dark matter. Here we show that the effective "dark matter" term in the metric function drastically changes the asymptotic behavior of the evolution of the wave function of a scalar field: after the Schwarzschild-like ringing phase, the ringing at another, non-Schwarzschildian, longer-lived frequency takes place before the beginning of the exponential asymptotic tail. Thus the evolution of the scalar field consists of the three qualitatively different stages: the Schwarzschild-like ringing phase, the effective dark matter ringing phase and the de Sitter phase characterized by exponential tails. The late time behavior of the electromagnetic field is qualitatively different as well: the exponential tails appear even in the absence of the effective de Sitter term. |
1806.01301 | Emmanuil Saridakis | Emmanuel N. Saridakis, Kazuharu Bamba, R. Myrzakulov, Fotios K.
Anagnostopoulos | Holographic dark energy through Tsallis entropy | 8 pages, 3 figures, version published in JCAP | JCAP 1812 (2018) no.12, 012 | 10.1088/1475-7516/2018/12/012 | FU-PCG-36 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In order to apply holography and entropy relations to the whole universe,
which is a gravitational and thus nonextensive system, for consistency one
should use the generalized definition for the universe horizon entropy, namely
Tsallis nonextensive entropy. We formulate Tsallis holographic dark energy,
which is a generalization of standard holographic dark energy quantified by a
new dimensionless parameter $\delta$, possessing the latter as a particular
sub-case. We provide a simple differential equation for the dark energy density
parameter, as well as an analytical expression for its equation-of-state
parameter. In this scenario the universe exhibits the usual thermal history,
namely the successive sequence of matter and dark-energy epochs, before
resulting in a complete dark energy domination in the far future. Additionally,
the dark energy equation-of-state parameter presents a rich behavior and,
according to the value of $\delta$, it can be quintessence-like, phantom-like,
or experience the phantom-divide crossing before or after the present time.
Finally, we confront the scenario with Supernovae type Ia and Hubble parameter
observational data, and we show that the agreement is very good, with $\delta$
preferring a value slightly larger than its standard value 1.
| [
{
"created": "Mon, 4 Jun 2018 18:07:21 GMT",
"version": "v1"
},
{
"created": "Tue, 11 Dec 2018 08:34:50 GMT",
"version": "v2"
}
] | 2018-12-12 | [
[
"Saridakis",
"Emmanuel N.",
""
],
[
"Bamba",
"Kazuharu",
""
],
[
"Myrzakulov",
"R.",
""
],
[
"Anagnostopoulos",
"Fotios K.",
""
]
] | In order to apply holography and entropy relations to the whole universe, which is a gravitational and thus nonextensive system, for consistency one should use the generalized definition for the universe horizon entropy, namely Tsallis nonextensive entropy. We formulate Tsallis holographic dark energy, which is a generalization of standard holographic dark energy quantified by a new dimensionless parameter $\delta$, possessing the latter as a particular sub-case. We provide a simple differential equation for the dark energy density parameter, as well as an analytical expression for its equation-of-state parameter. In this scenario the universe exhibits the usual thermal history, namely the successive sequence of matter and dark-energy epochs, before resulting in a complete dark energy domination in the far future. Additionally, the dark energy equation-of-state parameter presents a rich behavior and, according to the value of $\delta$, it can be quintessence-like, phantom-like, or experience the phantom-divide crossing before or after the present time. Finally, we confront the scenario with Supernovae type Ia and Hubble parameter observational data, and we show that the agreement is very good, with $\delta$ preferring a value slightly larger than its standard value 1. |
1701.00226 | Cosimo Bambi | Cosimo Bambi, Zheng Cao, Leonardo Modesto | Testing conformal gravity with astrophysical black holes | 5 pages, 2 figures. v2: refereed version | Phys. Rev. D 98, 024007 (2018) | 10.1103/PhysRevD.98.024007 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Weyl conformal symmetry can solve the problem the spacetime singularities
present in Einstein's gravity. In a recent paper, two of us have found a
singularity-free rotating black hole solution in conformal gravity. In addition
to the mass $M$ and the spin angular momentum $J$ of the black hole, the new
solution has a new parameter, $L$, which here we consider to be proportional to
the black hole mass. Since the solution is conformally equivalent to the Kerr
metric, photon trajectories are unchanged, while the structure of an accretion
disk around a black hole is affected by the value of the parameter $L$. In this
paper, we show that X-ray data of astrophysical black holes require $L/M <
1.2$.
| [
{
"created": "Sun, 1 Jan 2017 11:21:17 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Mar 2017 19:43:15 GMT",
"version": "v2"
}
] | 2018-07-11 | [
[
"Bambi",
"Cosimo",
""
],
[
"Cao",
"Zheng",
""
],
[
"Modesto",
"Leonardo",
""
]
] | Weyl conformal symmetry can solve the problem the spacetime singularities present in Einstein's gravity. In a recent paper, two of us have found a singularity-free rotating black hole solution in conformal gravity. In addition to the mass $M$ and the spin angular momentum $J$ of the black hole, the new solution has a new parameter, $L$, which here we consider to be proportional to the black hole mass. Since the solution is conformally equivalent to the Kerr metric, photon trajectories are unchanged, while the structure of an accretion disk around a black hole is affected by the value of the parameter $L$. In this paper, we show that X-ray data of astrophysical black holes require $L/M < 1.2$. |
1802.06486 | Vasilis Oikonomou | S.D. Odintsov, V.K. Oikonomou | Attractor Cosmology from non-minimally Coupled Gravity | PRD Accepted | null | 10.1103/PhysRevD.97.064005 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | By using a bottom-up reconstruction technique for non-minimally coupled
scalar-tensor theories, we realize the Einstein frame attractor cosmologies in
the $\Omega (\phi)$-Jordan frame. For our approach, what is needed for the
reconstruction method to work is the functional form of the non-minimal
coupling $\Omega(\phi)$ and of the scalar-to-tensor ratio, and also the
assumption of the slow-roll inflation in the $\Omega (\phi)$-Jordan frame. By
appropriately choosing the scalar-to-tensor ratio, we demonstrate that the
observational indices of the attractor cosmologies can be realized directly in
the $\Omega (\phi)$-Jordan frame. We investigate the special conditions that
are required to hold true in for this realization to occur, and we provide the
analytic form of the potential in the $\Omega (\phi)$-Jordan frame. Also, by
performing a conformal transformation, we find the corresponding Einstein frame
canonical scalar-tensor theory, and we calculate in detail the corresponding
observational indices. The result indicates that although the spectral index of
the primordial curvature perturbations is the same in the Jordan and Einstein
frames, at leading order in the $e$-foldings number, the scalar-to-tensor ratio
differs. We discuss the possible reasons behind this discrepancy, and we argue
that the difference is due to some approximation we performed to the functional
form of the potential in the Einstein frame, in order to obtain analytical
results, and also due to the difference in the definition of the $e$-foldings
number in the two frames, which is also pointed out in the related literature.
Finally, we find the $F(R)$ gravity corresponding to the Einstein frame
canonical scalar-tensor theory.
| [
{
"created": "Mon, 19 Feb 2018 01:53:35 GMT",
"version": "v1"
}
] | 2018-04-04 | [
[
"Odintsov",
"S. D.",
""
],
[
"Oikonomou",
"V. K.",
""
]
] | By using a bottom-up reconstruction technique for non-minimally coupled scalar-tensor theories, we realize the Einstein frame attractor cosmologies in the $\Omega (\phi)$-Jordan frame. For our approach, what is needed for the reconstruction method to work is the functional form of the non-minimal coupling $\Omega(\phi)$ and of the scalar-to-tensor ratio, and also the assumption of the slow-roll inflation in the $\Omega (\phi)$-Jordan frame. By appropriately choosing the scalar-to-tensor ratio, we demonstrate that the observational indices of the attractor cosmologies can be realized directly in the $\Omega (\phi)$-Jordan frame. We investigate the special conditions that are required to hold true in for this realization to occur, and we provide the analytic form of the potential in the $\Omega (\phi)$-Jordan frame. Also, by performing a conformal transformation, we find the corresponding Einstein frame canonical scalar-tensor theory, and we calculate in detail the corresponding observational indices. The result indicates that although the spectral index of the primordial curvature perturbations is the same in the Jordan and Einstein frames, at leading order in the $e$-foldings number, the scalar-to-tensor ratio differs. We discuss the possible reasons behind this discrepancy, and we argue that the difference is due to some approximation we performed to the functional form of the potential in the Einstein frame, in order to obtain analytical results, and also due to the difference in the definition of the $e$-foldings number in the two frames, which is also pointed out in the related literature. Finally, we find the $F(R)$ gravity corresponding to the Einstein frame canonical scalar-tensor theory. |
gr-qc/0607132 | Douglas Shaw | John D. Barrow and Douglas J. Shaw | Observable Effects of Scalar Fields and Varying Constants | Invited Festscrift Article | Gen.Rel.Grav.39:1235-1257,2007 | 10.1007/s10714-007-0453-z | null | gr-qc astro-ph | null | We show by using the method of matched asymptotic expansions that a
sufficient condition can be derived which determines when a local experiment
will detect the cosmological variation of a scalar field which is driving the
spacetime variation of a supposed constant of Nature. We extend our earlier
analyses of this problem by including the possibility that the local region is
undergoing collapse inside a virialised structure, like a galaxy or galaxy
cluster. We show by direct calculation that the sufficient condition is met to
high precision in our own local region and we can therefore legitimately use
local observations to place constraints upon the variation of "constants" of
Nature on cosmological scales.
| [
{
"created": "Fri, 28 Jul 2006 15:51:02 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Barrow",
"John D.",
""
],
[
"Shaw",
"Douglas J.",
""
]
] | We show by using the method of matched asymptotic expansions that a sufficient condition can be derived which determines when a local experiment will detect the cosmological variation of a scalar field which is driving the spacetime variation of a supposed constant of Nature. We extend our earlier analyses of this problem by including the possibility that the local region is undergoing collapse inside a virialised structure, like a galaxy or galaxy cluster. We show by direct calculation that the sufficient condition is met to high precision in our own local region and we can therefore legitimately use local observations to place constraints upon the variation of "constants" of Nature on cosmological scales. |
2402.13047 | Jo\~ao Lu\'is Rosa | Caio F. B. Macedo, Jo\~ao Lu\'is Rosa, Diego Rubiera-Garcia | Optical appearance of black holes surrounded by a dark matter halo | 21 pages, 17 figures | JCAP07(2024)046 | 10.1088/1475-7516/2024/07/046 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Black holes in General Relativity are described by space-time metrics that
are simpler in comparison to non-vacuum compact objects. However, given the
universality of the gravitational pull, it is expected that dark matter
accumulates around astrophysical black holes, which can have an impact in the
overall gravitational field, especially at galactic centers, and induce
non-negligible effects in their observational imprints. In this work we study
the optical appearance of a spherically symmetric black hole both when orbited
by isotropically emitting light sources and when surrounded by a (geometrically
and optically thin) accretion disk, while immersed in a dark matter halo. The
black hole geometry plus the dark matter halo come as a solution of Einstein's
field equations coupled to an anisotropic fluid whose density component follows
a Hermquist-type distribution. Even in situations in which the geodesic
description differs profoundly from the isolated black hole case, we find minor
modifications to the primary and secondary tracks of the isotropic orbiting
sources, and to the width, location, and relative luminosity of the
corresponding photon rings as compared to the Schwarzschild black hole at equal
black hole mass and emission models. This fact troubles distinguishing between
both geometries using present observations of very-long baseline
interferometry.
| [
{
"created": "Tue, 20 Feb 2024 14:35:54 GMT",
"version": "v1"
}
] | 2024-07-23 | [
[
"Macedo",
"Caio F. B.",
""
],
[
"Rosa",
"João Luís",
""
],
[
"Rubiera-Garcia",
"Diego",
""
]
] | Black holes in General Relativity are described by space-time metrics that are simpler in comparison to non-vacuum compact objects. However, given the universality of the gravitational pull, it is expected that dark matter accumulates around astrophysical black holes, which can have an impact in the overall gravitational field, especially at galactic centers, and induce non-negligible effects in their observational imprints. In this work we study the optical appearance of a spherically symmetric black hole both when orbited by isotropically emitting light sources and when surrounded by a (geometrically and optically thin) accretion disk, while immersed in a dark matter halo. The black hole geometry plus the dark matter halo come as a solution of Einstein's field equations coupled to an anisotropic fluid whose density component follows a Hermquist-type distribution. Even in situations in which the geodesic description differs profoundly from the isolated black hole case, we find minor modifications to the primary and secondary tracks of the isotropic orbiting sources, and to the width, location, and relative luminosity of the corresponding photon rings as compared to the Schwarzschild black hole at equal black hole mass and emission models. This fact troubles distinguishing between both geometries using present observations of very-long baseline interferometry. |
2009.03453 | Paul R. Anderson | Paul R. Anderson, Shohreh Gholizadeh Siahmazgi, Raymond D. Clark, and
Alessandro Fabbri | Method to compute the stress-energy tensor for a quantized scalar field
when a black hole forms from the collapse of a null shell | 40 pages, 4 figures | Phys. Rev. D 102, 125035 (2020) | 10.1103/PhysRevD.102.125035 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A method is given to compute the stress-energy tensor for a massless
minimally coupled scalar field in a spacetime where a black hole forms from the
collapse of a spherically symmetric null shell in four dimensions. Part of the
method involves matching the modes for the in vacuum state to a complete set of
modes in Schwarzschild spacetime. The other part involves subtracting from the
unrenormalized expression for the stress-energy tensor when the field is in the
in vacuum state, the corresponding expression when the field is in the Unruh
state and adding to this the renormalized stress-energy tensor for the field in
the Unruh state. The method is shown to work in the two-dimensional case where
the results are known.
| [
{
"created": "Mon, 7 Sep 2020 23:09:50 GMT",
"version": "v1"
}
] | 2021-01-04 | [
[
"Anderson",
"Paul R.",
""
],
[
"Siahmazgi",
"Shohreh Gholizadeh",
""
],
[
"Clark",
"Raymond D.",
""
],
[
"Fabbri",
"Alessandro",
""
]
] | A method is given to compute the stress-energy tensor for a massless minimally coupled scalar field in a spacetime where a black hole forms from the collapse of a spherically symmetric null shell in four dimensions. Part of the method involves matching the modes for the in vacuum state to a complete set of modes in Schwarzschild spacetime. The other part involves subtracting from the unrenormalized expression for the stress-energy tensor when the field is in the in vacuum state, the corresponding expression when the field is in the Unruh state and adding to this the renormalized stress-energy tensor for the field in the Unruh state. The method is shown to work in the two-dimensional case where the results are known. |
gr-qc/0512129 | Slava G. Turyshev | Slava G. Turyshev | The Science, Technology and Mission Design for the Laser Astrometric
Test of Relativity | 16 pages, 13 figures, 2 tables. To appear in proceedings of the "2006
IEEE Aerospace Conference," Big Sky, MT, March 4-11, 2006 | null | null | null | gr-qc | null | The Laser Astrometric Test of Relativity (LATOR) is a Michelson-Morley-type
experiment designed to test the Einstein's general theory of relativity in the
most intense gravitational environment available in the solar system -- the
close proximity to the Sun. By using independent time-series of highly accurate
measurements of the Shapiro time-delay (laser ranging accurate to 1 cm) and
interferometric astrometry (accurate to 0.1 picoradian), LATOR will measure
gravitational deflection of light by the solar gravity with accuracy of 1 part
in a billion, a factor ~30,000 better than currently available. LATOR will
perform series of highly-accurate tests of gravitation and cosmology in its
search for cosmological remnants of scalar field in the solar system. We
present science, technology and mission design for the LATOR mission.
| [
{
"created": "Thu, 22 Dec 2005 06:46:10 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Turyshev",
"Slava G.",
""
]
] | The Laser Astrometric Test of Relativity (LATOR) is a Michelson-Morley-type experiment designed to test the Einstein's general theory of relativity in the most intense gravitational environment available in the solar system -- the close proximity to the Sun. By using independent time-series of highly accurate measurements of the Shapiro time-delay (laser ranging accurate to 1 cm) and interferometric astrometry (accurate to 0.1 picoradian), LATOR will measure gravitational deflection of light by the solar gravity with accuracy of 1 part in a billion, a factor ~30,000 better than currently available. LATOR will perform series of highly-accurate tests of gravitation and cosmology in its search for cosmological remnants of scalar field in the solar system. We present science, technology and mission design for the LATOR mission. |
1508.00650 | Miguel Cruz | Miguel Cruz, Manuel Gonzalez-Espinoza, Joel Saavedra and Diego
Vargas-Arancibia | Scalar Perturbations of two-dimensional Horava-Lifshitz Black Holes | 18 pages, 1 figure. Accepted version in EPJC. arXiv admin note: text
overlap with arXiv:gr-qc/0701099 | Eur. Phys. J. C 76:75 (2016) | 10.1140/epjc/s10052-016-3927-x | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this article, we study the stability of black hole solutions found in the
context of dilatonic Horava-Lifshitz gravity in $1+1$ dimensions by means of
the quasinormal modes approach. In order to find the corresponding quasinormal
modes, we consider the perturbations of massive and massless scalar fields
minimally coupled to gravity. In both cases, we found that the quasinormal
modes have a discrete spectrum and are completely imaginary, which leads to
damping modes. For a massive scalar field and a non-vanishing cosmological
constant, our results suggest unstable behaviour for large values of the scalar
field mass.
| [
{
"created": "Tue, 4 Aug 2015 03:17:21 GMT",
"version": "v1"
},
{
"created": "Tue, 16 Feb 2016 04:23:43 GMT",
"version": "v2"
}
] | 2016-02-22 | [
[
"Cruz",
"Miguel",
""
],
[
"Gonzalez-Espinoza",
"Manuel",
""
],
[
"Saavedra",
"Joel",
""
],
[
"Vargas-Arancibia",
"Diego",
""
]
] | In this article, we study the stability of black hole solutions found in the context of dilatonic Horava-Lifshitz gravity in $1+1$ dimensions by means of the quasinormal modes approach. In order to find the corresponding quasinormal modes, we consider the perturbations of massive and massless scalar fields minimally coupled to gravity. In both cases, we found that the quasinormal modes have a discrete spectrum and are completely imaginary, which leads to damping modes. For a massive scalar field and a non-vanishing cosmological constant, our results suggest unstable behaviour for large values of the scalar field mass. |
0706.1109 | Roy Kerr | Roy P. Kerr | Discovering the Kerr and Kerr-Schild metrics | 34 pages, 2 figures, cupbook.cls. To appear in "The Kerr Spacetime",
Eds D.L. Wiltshire, M. Visser and S.M. Scott, Cambridge Univ. Press | null | null | null | gr-qc | null | An historical account of the reasoning that led to the discovery of the Kerr
and Kerr-Schild metrics in 1963-1964, and their physical interpretation as
rotating black holes, is presented.
| [
{
"created": "Fri, 8 Jun 2007 04:21:18 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Jan 2008 22:52:40 GMT",
"version": "v2"
}
] | 2008-01-15 | [
[
"Kerr",
"Roy P.",
""
]
] | An historical account of the reasoning that led to the discovery of the Kerr and Kerr-Schild metrics in 1963-1964, and their physical interpretation as rotating black holes, is presented. |
1910.10000 | Tays Miranda De Andrade | Tays Miranda, Emmanuel Frion and David Wands | Stochastic collapse | 1 figure, 3 tables. Version matching the one published in JCAP | JCAP 2001 (2020) no.01, 026 | 10.1088/1475-7516/2020/01/026 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate cosmological models described by a scalar field with an
exponential potential, and apply the stochastic formalism, which allows us to
study how quantum field fluctuations give rise to stochastic noise. This
modifies the classical dynamics of the scalar field at large scales, above a
coarse-graining scale. In particular we explore how quantum field fluctuations
perturb the equation of state on large scales which can lead to a quantum
instability of the classical collapse solution below the Planck scale in the
case of a pressureless collapse.
| [
{
"created": "Tue, 22 Oct 2019 14:17:15 GMT",
"version": "v1"
},
{
"created": "Thu, 23 Jan 2020 15:14:44 GMT",
"version": "v2"
}
] | 2020-01-24 | [
[
"Miranda",
"Tays",
""
],
[
"Frion",
"Emmanuel",
""
],
[
"Wands",
"David",
""
]
] | We investigate cosmological models described by a scalar field with an exponential potential, and apply the stochastic formalism, which allows us to study how quantum field fluctuations give rise to stochastic noise. This modifies the classical dynamics of the scalar field at large scales, above a coarse-graining scale. In particular we explore how quantum field fluctuations perturb the equation of state on large scales which can lead to a quantum instability of the classical collapse solution below the Planck scale in the case of a pressureless collapse. |
2112.06861 | LSC P&P Committee | The LIGO Scientific Collaboration, the Virgo Collaboration, and the
KAGRA Collaboration: R. Abbott, H. Abe, F. Acernese, K. Ackley, N. Adhikari,
R. X. Adhikari, V. K. Adkins, V. B. Adya, C. Affeldt, D. Agarwal, M. Agathos,
K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, T.
Akutsu, P. F. de Alarc\'on, S. Albanesi, R. A. Alfaidi, A. Allocca, P. A.
Altin, A. Amato, C. Anand, S. Anand, A. Ananyeva, S. B. Anderson, W. G.
Anderson, M. Ando, T. Andrade, N. Andres, M. Andr\'es-Carcasona, T. Andri\'c,
S. V. Angelova, S. Ansoldi, J. M. Antelis, S. Antier, T. Apostolatos, E. Z.
Appavuravther, S. Appert, S. K. Apple, K. Arai, A. Araya, M. C. Araya, J. S.
Areeda, M. Ar\`ene, N. Aritomi, N. Arnaud, M. Arogeti, S. M. Aronson, K. G.
Arun, H. Asada, Y. Asali, G. Ashton, Y. Aso, M. Assiduo, S. Assis de Souza
Melo, S. M. Aston, P. Astone, F. Aubin, K. AultONeal, C. Austin, S. Babak, F.
Badaracco, M. K. M. Bader, C. Badger, S. Bae, Y. Bae, A. M. Baer, S.
Bagnasco, Y. Bai, J. Baird, R. Bajpai, T. Baka, M. Ball, G. Ballardin, S. W.
Ballmer, A. Balsamo, G. Baltus, S. Banagiri, B. Banerjee, D. Bankar, J. C.
Barayoga, C. Barbieri, B. C. Barish, D. Barker, P. Barneo, F. Barone, B.
Barr, L. Barsotti, M. Barsuglia, D. Barta, J. Bartlett, M. A. Barton, I.
Bartos, S. Basak, R. Bassiri, A. Basti, M. Bawaj, J. C. Bayley, M. Bazzan, B.
R. Becher, B. B\'ecsy, V. M. Bedakihale, F. Beirnaert, M. Bejger, I.
Belahcene, V. Benedetto, D. Beniwal, M. G. Benjamin, T. F. Bennett, J. D.
Bentley, M. BenYaala, S. Bera, M. Berbel, F. Bergamin, B. K. Berger, S.
Bernuzzi, C. P. L. Berry, D. Bersanetti, A. Bertolini, J. Betzwieser, D.
Beveridge, R. Bhandare, A. V. Bhandari, U. Bhardwaj, R. Bhatt, D.
Bhattacharjee, S. Bhaumik, A. Bianchi, I. A. Bilenko, G. Billingsley, S.
Bini, R. Birney, O. Birnholtz, S. Biscans, M. Bischi, S. Biscoveanu, A.
Bisht, B. Biswas, M. Bitossi, M.-A. Bizouard, J. K. Blackburn, C. D. Blair,
D. G. Blair, R. M. Blair, F. Bobba, N. Bode, M. Bo\"er, G. Bogaert, M.
Boldrini, G. N. Bolingbroke, L. D. Bonavena, F. Bondu, E. Bonilla, R.
Bonnand, P. Booker, B. A. Boom, R. Bork, V. Boschi, N. Bose, S. Bose, V.
Bossilkov, V. Boudart, Y. Bouffanais, A. Bozzi, C. Bradaschia, P. R. Brady,
A. Bramley, A. Branch, M. Branchesi, J. E. Brau, M. Breschi, T. Briant, J. H.
Briggs, A. Brillet, M. Brinkmann, P. Brockill, A. F. Brooks, J. Brooks, D. D.
Brown, S. Brunett, G. Bruno, R. Bruntz, J. Bryant, F. Bucci, T. Bulik, H. J.
Bulten, A. Buonanno, K. Burtnyk, R. Buscicchio, D. Buskulic, C. Buy, R. L.
Byer, G. S. Cabourn Davies, G. Cabras, R. Cabrita, L. Cadonati, M. Caesar, G.
Cagnoli, C. Cahillane, J. Calder\'on Bustillo, J. D. Callaghan, T. A.
Callister, E. Calloni, J. Cameron, J. B. Camp, M. Canepa, S. Canevarolo, M.
Cannavacciuolo, K. C. Cannon, H. Cao, Z. Cao, E. Capocasa, E. Capote, G.
Carapella, F. Carbognani, M. Carlassara, J. B. Carlin, M. F. Carney, M.
Carpinelli, G. Carrillo, G. Carullo, T. L. Carver, J. Casanueva Diaz, C.
Casentini, G. Castaldi, S. Caudill, M. Cavagli\`a, F. Cavalier, R. Cavalieri,
G. Cella, P. Cerd\'a-Dur\'an, E. Cesarini, W. Chaibi, S. Chalathadka
Subrahmanya, E. Champion, C.-H. Chan, C. Chan, C. L. Chan, K. Chan, M. Chan,
K. Chandra, I. P. Chang, P. Chanial, S. Chao, C. Chapman-Bird, P. Charlton,
E. A. Chase, E. Chassande-Mottin, C. Chatterjee, Debarati Chatterjee, Deep
Chatterjee, M. Chaturvedi, S. Chaty, K. Chatziioannou, C. Chen, D. Chen, H.
Y. Chen, J. Chen, K. Chen, X. Chen, Y.-B. Chen, Y.-R. Chen, Z. Chen, H.
Cheng, C. K. Cheong, H. Y. Cheung, H. Y. Chia, F. Chiadini, C-Y. Chiang, G.
Chiarini, R. Chierici, A. Chincarini, M. L. Chiofalo, A. Chiummo, R. K.
Choudhary, S. Choudhary, N. Christensen, Q. Chu, Y-K. Chu, S. S. Y. Chua, K.
W. Chung, G. Ciani, P. Ciecielag, M. Cie\'slar, M. Cifaldi, A. A. Ciobanu, R.
Ciolfi, F. Cipriano, F. Clara, J. A. Clark, P. Clearwater, S. Clesse, F.
Cleva, E. Coccia, E. Codazzo, P.-F. Cohadon, D. E. Cohen, M. Colleoni, C. G.
Collette, A. Colombo, M. Colpi, C. M. Compton, M. Constancio Jr., L. Conti,
S. J. Cooper, P. Corban, T. R. Corbitt, I. Cordero-Carri\'on, S. Corezzi, K.
R. Corley, N. J. Cornish, D. Corre, A. Corsi, S. Cortese, C. A. Costa, R.
Cotesta, R. Cottingham, M. W. Coughlin, J.-P. Coulon, S. T. Countryman, B.
Cousins, P. Couvares, D. M. Coward, M. J. Cowart, D. C. Coyne, R. Coyne, J.
D. E. Creighton, T. D. Creighton, A. W. Criswell, M. Croquette, S. G.
Crowder, J. R. Cudell, T. J. Cullen, A. Cumming, R. Cummings, L. Cunningham,
E. Cuoco, M. Cury{\l}o, P. Dabadie, T. Dal Canton, S. Dall'Osso, G. D\'alya,
A. Dana, B. D'Angelo, S. Danilishin, S. D'Antonio, K. Danzmann, C.
Darsow-Fromm, A. Dasgupta, L. E. H. Datrier, Sayak Datta, Sayantani Datta, V.
Dattilo, I. Dave, M. Davier, D. Davis, M. C. Davis, E. J. Daw, R. Dean, D.
DeBra, M. Deenadayalan, J. Degallaix, M. De Laurentis, S. Del\'eglise, V. Del
Favero, F. De Lillo, N. De Lillo, D. Dell'Aquila, W. Del Pozzo, L. M.
DeMarchi, F. De Matteis, V. D'Emilio, N. Demos, T. Dent, A. Depasse, R. De
Pietri, R. De Rosa, C. De Rossi, R. DeSalvo, R. De Simone, S. Dhurandhar, M.
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Wong, M. Wright, C. Wu, D. S. Wu, H. Wu, D. M. Wysocki, L. Xiao, T. Yamada,
H. Yamamoto, K. Yamamoto, T. Yamamoto, K. Yamashita, R. Yamazaki, F. W. Yang,
K. Z. Yang, L. Yang, Y.-C. Yang, Y. Yang, Yang Yang, M. J. Yap, D. W. Yeeles,
S.-W. Yeh, A. B. Yelikar, M. Ying, J. Yokoyama, T. Yokozawa, J. Yoo, T.
Yoshioka, Hang Yu, Haocun Yu, H. Yuzurihara, A. Zadro\.zny, M. Zanolin, S.
Zeidler, T. Zelenova, J.-P. Zendri, M. Zevin, M. Zhan, H. Zhang, J. Zhang, L.
Zhang, R. Zhang, T. Zhang, Y. Zhang, C. Zhao, G. Zhao, Y. Zhao, Yue Zhao, R.
Zhou, Z. Zhou, X. J. Zhu, Z.-H. Zhu, A. B. Zimmerman, M. E. Zucker, J.
Zweizig | Tests of General Relativity with GWTC-3 | null | null | null | LIGO-P2100275 | gr-qc astro-ph.HE hep-th | http://creativecommons.org/licenses/by/4.0/ | The ever-increasing number of detections of gravitational waves (GWs) from
compact binaries by the Advanced LIGO and Advanced Virgo detectors allows us to
perform ever-more sensitive tests of general relativity (GR) in the dynamical
and strong-field regime of gravity. We perform a suite of tests of GR using the
compact binary signals observed during the second half of the third observing
run of those detectors. We restrict our analysis to the 15 confident signals
that have false alarm rates $\leq 10^{-3}\, {\rm yr}^{-1}$. In addition to
signals consistent with binary black hole (BH) mergers, the new events include
GW200115_042309, a signal consistent with a neutron star--BH merger. We find
the residual power, after subtracting the best fit waveform from the data for
each event, to be consistent with the detector noise. Additionally, we find all
the post-Newtonian deformation coefficients to be consistent with the
predictions from GR, with an improvement by a factor of ~2 in the -1PN
parameter. We also find that the spin-induced quadrupole moments of the binary
BH constituents are consistent with those of Kerr BHs in GR. We find no
evidence for dispersion of GWs, non-GR modes of polarization, or post-merger
echoes in the events that were analyzed. We update the bound on the mass of the
graviton, at 90% credibility, to $m_g \leq 1.27 \times 10^{-23}
\mathrm{eV}/c^2$. The final mass and final spin as inferred from the pre-merger
and post-merger parts of the waveform are consistent with each other. The
studies of the properties of the remnant BHs, including deviations of the
quasi-normal mode frequencies and damping times, show consistency with the
predictions of GR. In addition to considering signals individually, we also
combine results from the catalog of GW signals to calculate more precise
population constraints. We find no evidence in support of physics beyond GR.
| [
{
"created": "Mon, 13 Dec 2021 18:19:04 GMT",
"version": "v1"
}
] | 2021-12-14 | [
[
"The LIGO Scientific Collaboration",
"",
""
],
[
"the Virgo Collaboration",
"",
""
],
[
"the KAGRA Collaboration",
"",
""
],
[
"Abbott",
"R.",
""
],
[
"Abe",
"H.",
""
],
[
"Acernese",
"F.",
""
],
[
"Ackley",
"K... | The ever-increasing number of detections of gravitational waves (GWs) from compact binaries by the Advanced LIGO and Advanced Virgo detectors allows us to perform ever-more sensitive tests of general relativity (GR) in the dynamical and strong-field regime of gravity. We perform a suite of tests of GR using the compact binary signals observed during the second half of the third observing run of those detectors. We restrict our analysis to the 15 confident signals that have false alarm rates $\leq 10^{-3}\, {\rm yr}^{-1}$. In addition to signals consistent with binary black hole (BH) mergers, the new events include GW200115_042309, a signal consistent with a neutron star--BH merger. We find the residual power, after subtracting the best fit waveform from the data for each event, to be consistent with the detector noise. Additionally, we find all the post-Newtonian deformation coefficients to be consistent with the predictions from GR, with an improvement by a factor of ~2 in the -1PN parameter. We also find that the spin-induced quadrupole moments of the binary BH constituents are consistent with those of Kerr BHs in GR. We find no evidence for dispersion of GWs, non-GR modes of polarization, or post-merger echoes in the events that were analyzed. We update the bound on the mass of the graviton, at 90% credibility, to $m_g \leq 1.27 \times 10^{-23} \mathrm{eV}/c^2$. The final mass and final spin as inferred from the pre-merger and post-merger parts of the waveform are consistent with each other. The studies of the properties of the remnant BHs, including deviations of the quasi-normal mode frequencies and damping times, show consistency with the predictions of GR. In addition to considering signals individually, we also combine results from the catalog of GW signals to calculate more precise population constraints. We find no evidence in support of physics beyond GR. |
gr-qc/0501093 | Sergei Alexandrov | Sergei Alexandrov and Zoltan Kadar | Timelike surfaces in Lorentz covariant loop gravity and spin foam models | a wrong sign corrected in equation (65) | Class.Quant.Grav. 22 (2005) 3491-3510 | 10.1088/0264-9381/22/17/010 | SPIN-05/03, ITP-05/05 | gr-qc | null | We construct a canonical formulation of general relativity for the case of a
timelike foliation of spacetime. The formulation possesses explicit covariance
with respect to Lorentz transformations in the tangent space. Applying the loop
approach to quantize the theory we derive the spectrum of the area operator of
a two-dimensional surface. Its different branches are naturally associated to
spacelike and timelike surfaces. The results are compared with the predictions
of Lorentzian spin foam models. A restriction of the representations labeling
spin networks leads to perfect agreement between the states as well as the area
spectra in the two approaches.
| [
{
"created": "Fri, 28 Jan 2005 16:11:42 GMT",
"version": "v1"
},
{
"created": "Thu, 6 Oct 2005 14:54:42 GMT",
"version": "v2"
}
] | 2016-08-31 | [
[
"Alexandrov",
"Sergei",
""
],
[
"Kadar",
"Zoltan",
""
]
] | We construct a canonical formulation of general relativity for the case of a timelike foliation of spacetime. The formulation possesses explicit covariance with respect to Lorentz transformations in the tangent space. Applying the loop approach to quantize the theory we derive the spectrum of the area operator of a two-dimensional surface. Its different branches are naturally associated to spacelike and timelike surfaces. The results are compared with the predictions of Lorentzian spin foam models. A restriction of the representations labeling spin networks leads to perfect agreement between the states as well as the area spectra in the two approaches. |
1110.1321 | Julio Cesar Fabris | J. D. Barrow, A. B. Batista, G. Dito, J. C. Fabris, M. J. S. Houndjo | Sudden singularities survive massive quantum particle production | Latex file, 13 pages. New references, enlarged discussions in the
Introduction and in the Conclusions and some other minor modifications.
Accepted for publication in Physical Review D | Phys. Rev. D 84, 123518 (2011) | 10.1103/PhysRevD.84.123518 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We solve the Klein-Gordon equation for a massive, non-minimally coupled
scalar field, with a conformal coupling, undergoing cosmological evolution from
a radiation-dominated phase to a future sudden singularity. We show that, after
regularisation, the energy of the created particles is zero and the
back-reaction from quantum effects does not change the evolution of the
universe near the future singularity and cannot prevent the finite-time sudden
singularity.
| [
{
"created": "Thu, 6 Oct 2011 16:53:59 GMT",
"version": "v1"
},
{
"created": "Wed, 7 Dec 2011 11:31:33 GMT",
"version": "v2"
},
{
"created": "Thu, 28 Jun 2012 11:27:23 GMT",
"version": "v3"
}
] | 2013-05-29 | [
[
"Barrow",
"J. D.",
""
],
[
"Batista",
"A. B.",
""
],
[
"Dito",
"G.",
""
],
[
"Fabris",
"J. C.",
""
],
[
"Houndjo",
"M. J. S.",
""
]
] | We solve the Klein-Gordon equation for a massive, non-minimally coupled scalar field, with a conformal coupling, undergoing cosmological evolution from a radiation-dominated phase to a future sudden singularity. We show that, after regularisation, the energy of the created particles is zero and the back-reaction from quantum effects does not change the evolution of the universe near the future singularity and cannot prevent the finite-time sudden singularity. |
2005.00483 | Juliano Neves | Juliano C. S. Neves | Constraining the tidal charge of brane black holes using their shadows | 9 pages, 2 figures, 1 table. V2 with minor changes and new
references. Published in The European Physical Journal C | Eur. Phys. J. C 80, 717 (2020) | 10.1140/epjc/s10052-020-8321-z | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A constraint on the tidal charge generated within a brane world is shown.
Using the shadow of a rotating black hole in a brane context in order to
describe the M87* parameters recently announced by the Event Horizon Telescope
Collaboration, the deviation from circularity of the reported shadow produces
an upper bound on the bulk's nonlocal effect, which is conceived of as a tidal
charge in the four-dimensional brane induced by the five-dimensional bulk.
Therefore, a deviation from circularity $\lesssim 10\%$ leads to an upper bound
on the tidal charge $\lesssim 0.004M^2$.
| [
{
"created": "Fri, 1 May 2020 16:55:12 GMT",
"version": "v1"
},
{
"created": "Mon, 10 Aug 2020 14:09:28 GMT",
"version": "v2"
}
] | 2020-08-11 | [
[
"Neves",
"Juliano C. S.",
""
]
] | A constraint on the tidal charge generated within a brane world is shown. Using the shadow of a rotating black hole in a brane context in order to describe the M87* parameters recently announced by the Event Horizon Telescope Collaboration, the deviation from circularity of the reported shadow produces an upper bound on the bulk's nonlocal effect, which is conceived of as a tidal charge in the four-dimensional brane induced by the five-dimensional bulk. Therefore, a deviation from circularity $\lesssim 10\%$ leads to an upper bound on the tidal charge $\lesssim 0.004M^2$. |
gr-qc/0304045 | Ozgur Delice | Metin Arik and Ozgur Delice | Multiple Photonic Shells Around a Line Singularity | 6 pages | Gen.Rel.Grav. 35 (2003) 1285-1290 | 10.1023/A:1024458026755 | null | gr-qc | null | Line singularities including cosmic strings may be screened by photonic
shells until they appear as a planar wall.
| [
{
"created": "Thu, 10 Apr 2003 17:50:53 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Arik",
"Metin",
""
],
[
"Delice",
"Ozgur",
""
]
] | Line singularities including cosmic strings may be screened by photonic shells until they appear as a planar wall. |
1809.07992 | Roberto Peron Dr. | David Lucchesi, Luciano Anselmo, Massimo Bassan, Carmelo Magnafico,
Carmen Pardini, Roberto Peron, Giuseppe Pucacco, Ruggero Stanga, Massimo
Visco | Satellite Laser Ranging and General Relativity measurements in the field
of the Earth: state of the art and perspectives | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recent results of the LARASE research program in terms of models improvements
and relativistic measurements are presented. In particular, the results
regarding the development of new models for the non-gravitational perturbations
that affect the orbit of the LAGEOS and LARES satellites are described and
discussed. These are subtle and complex effects that need a deep knowledge of
the structure of the satellite and of its physical characteristics in order to
be correctly accounted for. In the field of gravitational measurements, we
introduce a new and precise measurement of the relativistic Lense-Thirring
precession. The role of the errors related to the knowledge of the
gravitational field of the Earth in this kind of measurements is also
discussed. Finally, the main results in relativistic measurements and
constraints obtained during the last few years by means of the laser tracking
of passive satellites are summarized. The key role of the Satellite Laser
Ranging technique in these activities is highlighted, together with the sinergy
it produces between space geodesy and fundamental physics measurements.
| [
{
"created": "Fri, 21 Sep 2018 09:09:10 GMT",
"version": "v1"
}
] | 2018-09-24 | [
[
"Lucchesi",
"David",
""
],
[
"Anselmo",
"Luciano",
""
],
[
"Bassan",
"Massimo",
""
],
[
"Magnafico",
"Carmelo",
""
],
[
"Pardini",
"Carmen",
""
],
[
"Peron",
"Roberto",
""
],
[
"Pucacco",
"Giuseppe",
""
]... | Recent results of the LARASE research program in terms of models improvements and relativistic measurements are presented. In particular, the results regarding the development of new models for the non-gravitational perturbations that affect the orbit of the LAGEOS and LARES satellites are described and discussed. These are subtle and complex effects that need a deep knowledge of the structure of the satellite and of its physical characteristics in order to be correctly accounted for. In the field of gravitational measurements, we introduce a new and precise measurement of the relativistic Lense-Thirring precession. The role of the errors related to the knowledge of the gravitational field of the Earth in this kind of measurements is also discussed. Finally, the main results in relativistic measurements and constraints obtained during the last few years by means of the laser tracking of passive satellites are summarized. The key role of the Satellite Laser Ranging technique in these activities is highlighted, together with the sinergy it produces between space geodesy and fundamental physics measurements. |
gr-qc/9307030 | Mourad | J.Madore and J. Mourad | A Noncommutative Extension of Gravity | 4 pages. Talk delivered at the 'journ\'ees Relativistes 93' | Int.J.Mod.Phys.D3:221-224,1994 | 10.1142/S0218271894000332 | null | gr-qc | null | The commutative algebra of functions on a manifold is extended to a
noncommutative algebra by considering its tensor product with the algebra of
nxn complex matrices. Noncommutative geometry is used to formulate an extension
of the Einstein-Hilbert action. The result is shown to be equivalent to the
usual Kaluza-Klein theory with the manifold SUn as an internal space, in a
truncated approximation.
| [
{
"created": "Thu, 22 Jul 1993 16:55:13 GMT",
"version": "v1"
}
] | 2011-04-20 | [
[
"Madore",
"J.",
""
],
[
"Mourad",
"J.",
""
]
] | The commutative algebra of functions on a manifold is extended to a noncommutative algebra by considering its tensor product with the algebra of nxn complex matrices. Noncommutative geometry is used to formulate an extension of the Einstein-Hilbert action. The result is shown to be equivalent to the usual Kaluza-Klein theory with the manifold SUn as an internal space, in a truncated approximation. |
gr-qc/0108002 | Volker Perlick | Wolfgang Hasse and Volker Perlick | Gravitational lensing in spherically symmetric static spacetimes with
centrifugal force reversal | 18 pages, 3 eps-figures | Gen.Rel.Grav.34:415-433,2002 | 10.1023/A:1015384604371 | AEI-2001-100 | gr-qc | null | In Schwarzschild spacetime the value $r=3m$ of the radius coordinate is
characterized by three different properties: (a) there is a ``light sphere'',
(b) there is ``centrifugal force reversal'', (c) it is the upper limiting
radius for a non-transparent Schwarschild source to act as a gravitational lens
that produces infinitely many images. In this paper we prove a theorem to the
effect that these three properties are intimately related in {\em any}
spherically symmetric static spacetime. We illustrate the general results with
some examples including black-hole spacetimes and Morris-Thorne wormholes.
| [
{
"created": "Wed, 1 Aug 2001 15:02:14 GMT",
"version": "v1"
}
] | 2010-11-19 | [
[
"Hasse",
"Wolfgang",
""
],
[
"Perlick",
"Volker",
""
]
] | In Schwarzschild spacetime the value $r=3m$ of the radius coordinate is characterized by three different properties: (a) there is a ``light sphere'', (b) there is ``centrifugal force reversal'', (c) it is the upper limiting radius for a non-transparent Schwarschild source to act as a gravitational lens that produces infinitely many images. In this paper we prove a theorem to the effect that these three properties are intimately related in {\em any} spherically symmetric static spacetime. We illustrate the general results with some examples including black-hole spacetimes and Morris-Thorne wormholes. |
2211.07002 | Hang Yu | Hang Yu and Nevin N. Weinberg and Phil Arras and James Kwon and
Tejaswi Venumadhav | Beyond the linear tide: impact of the non-linear tidal response of
neutron stars on gravitational waveforms from binary inspirals | 20 pages, 9 figures. Accepted for publication in MNRAS | null | 10.1093/mnras/stac3614 | null | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by-nc-sa/4.0/ | Tidal interactions in coalescing binary neutron stars modify the dynamics of
the inspiral and hence imprint a signature on their gravitational wave (GW)
signals in the form of an extra phase shift. We need accurate models for the
tidal phase shift in order to constrain the supranuclear equation of state from
observations. In previous studies, GW waveform models were typically
constructed by treating the tide as a linear response to a perturbing tidal
field. In this work, we incorporate non-linear corrections due to hydrodynamic
three- and four-mode interactions and show how they can improve the accuracy
and explanatory power of waveform models. We set up and numerically solve the
coupled differential equations for the orbit and the modes and analytically
derive solutions of the system's equilibrium configuration. Our analytical
solutions agree well with the numerical ones up to the merger and involve only
algebraic relations, allowing for fast phase shift and waveform evaluations for
different equations of state over a large parameter space. We find that, at
Newtonian order, non-linear fluid effects can enhance the tidal phase shift by
$\gtrsim 1\,{\rm radian}$ at a GW frequency of 1000 Hz, corresponding to a
$10-20\%$ correction to the linear theory. The scale of the additional phase
shift near the merger is consistent with the difference between numerical
relativity and theoretical predictions that account only for the linear tide.
Non-linear fluid effects are thus important when interpreting the results of
numerical relativity and in the construction of waveform models for current and
future GW detectors.
| [
{
"created": "Sun, 13 Nov 2022 19:43:44 GMT",
"version": "v1"
},
{
"created": "Fri, 6 Jan 2023 23:10:39 GMT",
"version": "v2"
}
] | 2023-01-10 | [
[
"Yu",
"Hang",
""
],
[
"Weinberg",
"Nevin N.",
""
],
[
"Arras",
"Phil",
""
],
[
"Kwon",
"James",
""
],
[
"Venumadhav",
"Tejaswi",
""
]
] | Tidal interactions in coalescing binary neutron stars modify the dynamics of the inspiral and hence imprint a signature on their gravitational wave (GW) signals in the form of an extra phase shift. We need accurate models for the tidal phase shift in order to constrain the supranuclear equation of state from observations. In previous studies, GW waveform models were typically constructed by treating the tide as a linear response to a perturbing tidal field. In this work, we incorporate non-linear corrections due to hydrodynamic three- and four-mode interactions and show how they can improve the accuracy and explanatory power of waveform models. We set up and numerically solve the coupled differential equations for the orbit and the modes and analytically derive solutions of the system's equilibrium configuration. Our analytical solutions agree well with the numerical ones up to the merger and involve only algebraic relations, allowing for fast phase shift and waveform evaluations for different equations of state over a large parameter space. We find that, at Newtonian order, non-linear fluid effects can enhance the tidal phase shift by $\gtrsim 1\,{\rm radian}$ at a GW frequency of 1000 Hz, corresponding to a $10-20\%$ correction to the linear theory. The scale of the additional phase shift near the merger is consistent with the difference between numerical relativity and theoretical predictions that account only for the linear tide. Non-linear fluid effects are thus important when interpreting the results of numerical relativity and in the construction of waveform models for current and future GW detectors. |
0711.2279 | Andrew DeBenedictis | A. DeBenedictis | Developments in Black Hole Research: Classical, Semi-classical, and
Quantum | 59 pages, 17 figures (some are quality reduced due to file size
restrictions). Version 2 has extra references and minor changes to match
version for publication. Invited chapter to appear in an edited collection
'Classical and Quantum Gravity Research', Nova Science Publishers | Classical and Quantum Gravity Research, 371-426, (2008), Nova Sci.
Pub. ISBN 978-1-60456-366-5 | null | null | gr-qc | null | The possible existence of black holes has fascinated scientists at least
since Michell and Laplace's proposal that a gravitating object could exist from
which light could not escape. In the 20th century, in light of the general
theory of relativity, it became apparent that, were such objects to exist,
their structure would be far richer than originally imagined. Today,
astronomical observations strongly suggest that either black holes, or objects
with similar properties, not only exist but may well be abundant in our
universe. In light of this, black hole research is now not only motivated by
the fascinating theoretical properties such objects must possess but also as an
attempt to better understand the universe around us. We review here some
selected developments in black hole research, from a review of its early
history to current topics in black hole physics research. Black holes have been
studied at all levels; classically, semi-classically, and more recently, as an
arena to test predictions of candidate theories of quantum gravity. We will
review here progress and current research at all these levels as well as
discuss some proposed alternatives to black holes.
| [
{
"created": "Wed, 14 Nov 2007 19:25:27 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Mar 2008 01:01:53 GMT",
"version": "v2"
}
] | 2008-11-15 | [
[
"DeBenedictis",
"A.",
""
]
] | The possible existence of black holes has fascinated scientists at least since Michell and Laplace's proposal that a gravitating object could exist from which light could not escape. In the 20th century, in light of the general theory of relativity, it became apparent that, were such objects to exist, their structure would be far richer than originally imagined. Today, astronomical observations strongly suggest that either black holes, or objects with similar properties, not only exist but may well be abundant in our universe. In light of this, black hole research is now not only motivated by the fascinating theoretical properties such objects must possess but also as an attempt to better understand the universe around us. We review here some selected developments in black hole research, from a review of its early history to current topics in black hole physics research. Black holes have been studied at all levels; classically, semi-classically, and more recently, as an arena to test predictions of candidate theories of quantum gravity. We will review here progress and current research at all these levels as well as discuss some proposed alternatives to black holes. |
2307.04196 | F Shojai | S. Cheraghchi, F. Shojai and M.H. Abbassi | Trans-Planckian Effect in $f(R)$ Cosmology | 21 pages, 5 figures, 1 table, | 2023 Phys. Scr. 98 085310 | 10.1088/1402-4896/ace706 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Apart from the assumption that the inflation started at an infinite time in
the past, the more realistic initial state of the quantum fluctuations is
described by a mixed quantum state imposed at a finite value of the initial
time. One of the most important non-trivial vacua is the $\alpha$-vacuum, which
is specified by a momentum cutoff $\Lambda$ \cite{Danielsson:2002kx}. As a
consequence, the initial condition is imposed at different initial times for
the different $k$-modes. This modifies the amplitude of the quantum
fluctuations, and thus the corresponding power spectra. In this paper, we
consider the imprint of the $\alpha$-vacuum state on the power spectrum of
scalar perturbations in a generic $f(R)$ gravity by assuming an ultraviolet
cutoff $\Lambda$. As a specific model, we consider the Starobinsky model and
find the trans-Planckian power spectrum. We find that the leading order
corrections to the scalar power spectra in $f(R)$ gravity have an oscillatory
behavior as in general relativity \cite{Lim}, and furthermore, the results are
in sufficient agreement with the $\Lambda$CDM model.
| [
{
"created": "Sun, 9 Jul 2023 15:05:26 GMT",
"version": "v1"
}
] | 2023-08-02 | [
[
"Cheraghchi",
"S.",
""
],
[
"Shojai",
"F.",
""
],
[
"Abbassi",
"M. H.",
""
]
] | Apart from the assumption that the inflation started at an infinite time in the past, the more realistic initial state of the quantum fluctuations is described by a mixed quantum state imposed at a finite value of the initial time. One of the most important non-trivial vacua is the $\alpha$-vacuum, which is specified by a momentum cutoff $\Lambda$ \cite{Danielsson:2002kx}. As a consequence, the initial condition is imposed at different initial times for the different $k$-modes. This modifies the amplitude of the quantum fluctuations, and thus the corresponding power spectra. In this paper, we consider the imprint of the $\alpha$-vacuum state on the power spectrum of scalar perturbations in a generic $f(R)$ gravity by assuming an ultraviolet cutoff $\Lambda$. As a specific model, we consider the Starobinsky model and find the trans-Planckian power spectrum. We find that the leading order corrections to the scalar power spectra in $f(R)$ gravity have an oscillatory behavior as in general relativity \cite{Lim}, and furthermore, the results are in sufficient agreement with the $\Lambda$CDM model. |
2012.03269 | Xuefeng Zhang | Bobing Ye, Xuefeng Zhang, Yanwei Ding, Yunhe Meng | Eclipse avoidance in TianQin orbit selection | 7 pages, 7 figures, to match the published version | Phys. Rev. D 103, 042007 (2021) | 10.1103/PhysRevD.103.042007 | null | gr-qc astro-ph.IM | http://creativecommons.org/licenses/by/4.0/ | In future geocentric space-based gravitational-wave observatory missions,
eclipses due to passing through the Moon's and Earth's shadows can negatively
impact the sciencecraft's thermal stability and steady power supply. The
occurrence should be reduced as much as possible in orbit design. In regard to
TianQin's circular high orbits, we tackle the combined challenges of avoiding
eclipses and stabilizing the nearly equilateral-triangle constellation. Two
strategies are proposed, including initial phase selection and orbit resizing
to 1:8 synodic resonance with the Moon, where the latter involves slightly
raising TianQin's preliminary orbital radius of $1\times 10^5$ km to $\sim
100900$ km. As the result, we have identified pure-gravity target orbits with a
permitted initial phase range of $\sim 15^\circ$, which can maintain
eclipse-free during the 3+3 month observation windows throughout a 5-year
mission started in 2034, and meanwhile fulfil the constellation stability
requirements. Thereby the eclipse issue for TianQin can be largely resolved.
| [
{
"created": "Sun, 6 Dec 2020 13:46:39 GMT",
"version": "v1"
},
{
"created": "Tue, 16 Feb 2021 02:15:58 GMT",
"version": "v2"
}
] | 2021-02-17 | [
[
"Ye",
"Bobing",
""
],
[
"Zhang",
"Xuefeng",
""
],
[
"Ding",
"Yanwei",
""
],
[
"Meng",
"Yunhe",
""
]
] | In future geocentric space-based gravitational-wave observatory missions, eclipses due to passing through the Moon's and Earth's shadows can negatively impact the sciencecraft's thermal stability and steady power supply. The occurrence should be reduced as much as possible in orbit design. In regard to TianQin's circular high orbits, we tackle the combined challenges of avoiding eclipses and stabilizing the nearly equilateral-triangle constellation. Two strategies are proposed, including initial phase selection and orbit resizing to 1:8 synodic resonance with the Moon, where the latter involves slightly raising TianQin's preliminary orbital radius of $1\times 10^5$ km to $\sim 100900$ km. As the result, we have identified pure-gravity target orbits with a permitted initial phase range of $\sim 15^\circ$, which can maintain eclipse-free during the 3+3 month observation windows throughout a 5-year mission started in 2034, and meanwhile fulfil the constellation stability requirements. Thereby the eclipse issue for TianQin can be largely resolved. |
1505.03157 | Raymond Ang\'elil | Raymond Ang\'elil, Prasenjit Saha | Geometrical vs wave optics under gravitational waves | Accepted for publication in Physical Review D, matches published
version | null | 10.1103/PhysRevD.91.124007 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present some new derivations of the effect of a plane gravitational wave
on a light ray. A simple interpretation of the results is that a gravitational
wave causes a phase modulation of electromagnetic waves. We arrive at this
picture from two contrasting directions, namely null geodesics and Maxwell's
equations, or, geometric and wave optics. Under geometric optics, we express
the geodesic equations in Hamiltonian form and solve perturbatively for the
effect of gravitational waves. We find that the well-known time-delay formula
for light generalizes trivially to massive particles. We also recover, by way
of a Hamilton-Jacobi equation, the phase modulation obtained under wave optics.
Turning then to wave optics - rather than solving Maxwell's equations directly
for the fields, as in most previous approaches - we derive a perturbed wave
equation (perturbed by the gravitational wave) for the electromagnetic
four-potential. From this wave equation it follows that the four-potential and
the electric and magnetic fields all experience the same phase modulation.
Applying such a phase modulation to a superposition of plane waves
corresponding to a Gaussian wave packet leads to time delays.
| [
{
"created": "Tue, 12 May 2015 20:01:53 GMT",
"version": "v1"
},
{
"created": "Wed, 20 May 2015 14:28:01 GMT",
"version": "v2"
}
] | 2015-06-17 | [
[
"Angélil",
"Raymond",
""
],
[
"Saha",
"Prasenjit",
""
]
] | We present some new derivations of the effect of a plane gravitational wave on a light ray. A simple interpretation of the results is that a gravitational wave causes a phase modulation of electromagnetic waves. We arrive at this picture from two contrasting directions, namely null geodesics and Maxwell's equations, or, geometric and wave optics. Under geometric optics, we express the geodesic equations in Hamiltonian form and solve perturbatively for the effect of gravitational waves. We find that the well-known time-delay formula for light generalizes trivially to massive particles. We also recover, by way of a Hamilton-Jacobi equation, the phase modulation obtained under wave optics. Turning then to wave optics - rather than solving Maxwell's equations directly for the fields, as in most previous approaches - we derive a perturbed wave equation (perturbed by the gravitational wave) for the electromagnetic four-potential. From this wave equation it follows that the four-potential and the electric and magnetic fields all experience the same phase modulation. Applying such a phase modulation to a superposition of plane waves corresponding to a Gaussian wave packet leads to time delays. |
2401.02493 | Miquel Miravet-Ten\'es | Miquel Miravet-Ten\'es, Davide Guerra, Milton Ruiz, Pablo
Cerd\'a-Dur\'an, Jos\'e A. Font | Identifying thermal effects in neutron star merger remnants with
model-agnostic waveform reconstructions and third-generation detectors | 15 pages, 8 figures, 3 tables | null | null | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We explore the prospects for identifying differences in simulated
gravitational-wave signals of binary neutron star (BNS) mergers associated with
the way thermal effects are incorporated in the numerical-relativity modelling.
We consider a hybrid approach in which the equation of state (EoS) comprises a
cold, zero temperature, piecewise-polytropic part and a thermal part described
by an ideal gas, and a tabulated approach based on self-consistent,
microphysical, finite-temperature EoS. We use time-domain waveforms
corresponding to BNS merger simulations with four different EoS. Those are
injected into Gaussian noise given by the sensitivity of the third-generation
detector Einstein Telescope and reconstructed using BayesWave, a Bayesian
data-analysis algorithm that recovers the signals through a model-agnostic
approach. The two representations of thermal effects result in frequency shifts
of the dominant peaks in the spectra of the post-merger signals, for both the
quadrupole fundamental mode and the late-time inertial modes. For some of the
EoS investigated those differences are large enough to be told apart,
especially in the early post-merger phase when the signal amplitude is the
loudest.
| [
{
"created": "Thu, 4 Jan 2024 19:06:34 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Jan 2024 08:45:40 GMT",
"version": "v2"
}
] | 2024-01-19 | [
[
"Miravet-Tenés",
"Miquel",
""
],
[
"Guerra",
"Davide",
""
],
[
"Ruiz",
"Milton",
""
],
[
"Cerdá-Durán",
"Pablo",
""
],
[
"Font",
"José A.",
""
]
] | We explore the prospects for identifying differences in simulated gravitational-wave signals of binary neutron star (BNS) mergers associated with the way thermal effects are incorporated in the numerical-relativity modelling. We consider a hybrid approach in which the equation of state (EoS) comprises a cold, zero temperature, piecewise-polytropic part and a thermal part described by an ideal gas, and a tabulated approach based on self-consistent, microphysical, finite-temperature EoS. We use time-domain waveforms corresponding to BNS merger simulations with four different EoS. Those are injected into Gaussian noise given by the sensitivity of the third-generation detector Einstein Telescope and reconstructed using BayesWave, a Bayesian data-analysis algorithm that recovers the signals through a model-agnostic approach. The two representations of thermal effects result in frequency shifts of the dominant peaks in the spectra of the post-merger signals, for both the quadrupole fundamental mode and the late-time inertial modes. For some of the EoS investigated those differences are large enough to be told apart, especially in the early post-merger phase when the signal amplitude is the loudest. |
1406.0841 | Vyacheslav Ivanovich Dokuchaev | E. O. Babichev, V. I. Dokuchaev and Yu. N. Eroshenko | Black holes in the presence of dark energy | 25 pages, 10 figures, review paper | Phys.-Usp. 56 (2013) 1155-1175; Uspekhi Fiz. Nauk 183 (2013)
1257-1280 | 10.3367/UFNe.0183.201312a.1257 | LPT-Orsay-14-33 | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The new, rapidly developing field of theoretical research --- studies of dark
energy interacting with black holes (and, in particular, accreting onto black
holes) --- is reviewed. The term `dark energy' is meant to cover a wide range
of field theory models, as well as perfect fluids with various equations of
state, including cosmological dark energy. Various accretion models are
analyzed in terms of the simplest test field approximation or by allowing back
reaction on the black-hole metric. The behavior of various types of dark energy
in the vicinity of Schwarzschild and electrically charged black holes is
examined. Nontrivial effects due to the presence of dark energy in the black
hole vicinity are discussed. In particular, a physical explanation is given of
why the black hole mass decreases when phantom energy is being accreted, a
process in which the basic energy conditions of the famous theorem of
nondecreasing horizon area in classical black holes are violated. The
theoretical possibility of a signal escaping from beneath the black hole event
horizon is discussed for a number of dark energy models. Finally, the violation
of the laws of thermodynamics by black holes in the presence of noncanonical
fields is considered.
| [
{
"created": "Tue, 3 Jun 2014 16:02:57 GMT",
"version": "v1"
}
] | 2014-06-11 | [
[
"Babichev",
"E. O.",
""
],
[
"Dokuchaev",
"V. I.",
""
],
[
"Eroshenko",
"Yu. N.",
""
]
] | The new, rapidly developing field of theoretical research --- studies of dark energy interacting with black holes (and, in particular, accreting onto black holes) --- is reviewed. The term `dark energy' is meant to cover a wide range of field theory models, as well as perfect fluids with various equations of state, including cosmological dark energy. Various accretion models are analyzed in terms of the simplest test field approximation or by allowing back reaction on the black-hole metric. The behavior of various types of dark energy in the vicinity of Schwarzschild and electrically charged black holes is examined. Nontrivial effects due to the presence of dark energy in the black hole vicinity are discussed. In particular, a physical explanation is given of why the black hole mass decreases when phantom energy is being accreted, a process in which the basic energy conditions of the famous theorem of nondecreasing horizon area in classical black holes are violated. The theoretical possibility of a signal escaping from beneath the black hole event horizon is discussed for a number of dark energy models. Finally, the violation of the laws of thermodynamics by black holes in the presence of noncanonical fields is considered. |
gr-qc/9905058 | Masaru shibata | Masaru Shibata (UIUC & Osaka U.) | Fully general relativistic simulation of merging binary clusters --
Spatial gauge condition -- | 22 pages + 17 pages of figures (ps file). To be published in Prog.
Theor. Phys. 101, June (1999) | Prog.Theor.Phys. 101 (1999) 1199-1233 | 10.1143/PTP.101.1199 | null | gr-qc | null | We have carried out simulations of the coalescence between two relativistic
clusters of collisionless particles using a 3D numerical relativity code. We
have adopted a new spatial gauge condition obtained by slightly modifying the
minimum distortion gauge condition proposed by Smarr and York and resulting in
a simpler equation for the shift vector. Using this gauge condition, we have
performed several simulations of the merger between two identical clusters in
which we have varied the compaction, the type of internal motion in the
clusters, and the magnitude of the orbital velocity. As a result of the
coalescence, either a new rotating cluster or a black hole is formed. In the
case in which a black hole is not formed, simulations could be carried out for
a time much longer than the dynamical time scale, and the resulting
gravitational waveforms were calculated fairly accurately: In these cases, the
amplitude of gravitational waves emitted can be $\sim
10^{-18}(M/10^6M_{\odot})$ at a distance 4000Mpc, and $\sim 0.5%$ of the rest
mass energy may be dissipated by the gravitational wave emission in the final
phase of the merger. These results confirm that the new spatial gauge condition
is promising in many problems at least up to the formation of black holes. In
the case in which a black hole is formed, on the other hand, the gauge
condition seems to be less adequate, but we suggest a strategy to improve it in
this case. All of the results obtained confirm the robustness of our
formulation and the ability of our code for stable evolution of strong
gravitational fields of compact binaries.
| [
{
"created": "Mon, 17 May 1999 18:29:42 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Shibata",
"Masaru",
"",
"UIUC & Osaka U."
]
] | We have carried out simulations of the coalescence between two relativistic clusters of collisionless particles using a 3D numerical relativity code. We have adopted a new spatial gauge condition obtained by slightly modifying the minimum distortion gauge condition proposed by Smarr and York and resulting in a simpler equation for the shift vector. Using this gauge condition, we have performed several simulations of the merger between two identical clusters in which we have varied the compaction, the type of internal motion in the clusters, and the magnitude of the orbital velocity. As a result of the coalescence, either a new rotating cluster or a black hole is formed. In the case in which a black hole is not formed, simulations could be carried out for a time much longer than the dynamical time scale, and the resulting gravitational waveforms were calculated fairly accurately: In these cases, the amplitude of gravitational waves emitted can be $\sim 10^{-18}(M/10^6M_{\odot})$ at a distance 4000Mpc, and $\sim 0.5%$ of the rest mass energy may be dissipated by the gravitational wave emission in the final phase of the merger. These results confirm that the new spatial gauge condition is promising in many problems at least up to the formation of black holes. In the case in which a black hole is formed, on the other hand, the gauge condition seems to be less adequate, but we suggest a strategy to improve it in this case. All of the results obtained confirm the robustness of our formulation and the ability of our code for stable evolution of strong gravitational fields of compact binaries. |
gr-qc/9304043 | Ranjeet S. Tate | Ranjeet S. Tate, (Ph.D. Dissertation, Syracuse University) | An algebraic approach to the quantization of cosntrained systems: finite
dimensional examples | 124 pages, LaTeX (run twice before printing), SU-GP-92/8-1. (Minor
corruption (extra blank line at line 2994) hopefully fixed.) | null | null | null | gr-qc | null | From the point of view of canonical quantum gravity, it has become imperative
to find a framework for quantization which provides a {\em general}
prescription to find the physical inner product, and is flexible enough to
accommodate non-canonical variables. In this dissertation I consider an
algebraic formulation of the Dirac approach to the quantization of constrained
systems, due to A. Ashtekar. The Dirac quantization program is augmented by a
general principle to find the inner product on physical states. Essentially,
the Hermiticity conditions on physical operators determine this inner product.
I also clarify the role in quantum theory of possible algebraic identities
between the elementary variables. I use this approach to quantize various
finite dimensional systems. Some of these models test the new aspects of the
algebraic framework. Others bear qualitative similarities to \gr, and may give
some insight into the pitfalls lurking in \qg. In (spatially compact) general
relativity, the Hamiltonian is constrained to vanish. I present various
approaches one can take to obtain an interpretation of the quantum theory of
such ``dynamically constrained'' systems. I apply some of these ideas to the
Bianchi I cosmology, and analyze the issue of the initial singularity in
quantum theory.
| [
{
"created": "Fri, 30 Apr 1993 00:41:14 GMT",
"version": "v1"
},
{
"created": "Fri, 30 Apr 1993 18:48:37 GMT",
"version": "v2"
}
] | 2016-08-31 | [
[
"Tate",
"Ranjeet S.",
""
]
] | From the point of view of canonical quantum gravity, it has become imperative to find a framework for quantization which provides a {\em general} prescription to find the physical inner product, and is flexible enough to accommodate non-canonical variables. In this dissertation I consider an algebraic formulation of the Dirac approach to the quantization of constrained systems, due to A. Ashtekar. The Dirac quantization program is augmented by a general principle to find the inner product on physical states. Essentially, the Hermiticity conditions on physical operators determine this inner product. I also clarify the role in quantum theory of possible algebraic identities between the elementary variables. I use this approach to quantize various finite dimensional systems. Some of these models test the new aspects of the algebraic framework. Others bear qualitative similarities to \gr, and may give some insight into the pitfalls lurking in \qg. In (spatially compact) general relativity, the Hamiltonian is constrained to vanish. I present various approaches one can take to obtain an interpretation of the quantum theory of such ``dynamically constrained'' systems. I apply some of these ideas to the Bianchi I cosmology, and analyze the issue of the initial singularity in quantum theory. |
2007.05509 | Suvankar Paul | Suvankar Paul | Strong gravitational lensing by a strongly naked null singularity | 18 pages, 6 figures, minor corrections, matches the published version
at PRD | Phys. Rev. D 102, 064045 (2020) | 10.1103/PhysRevD.102.064045 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study strong gravitational lensing in a static, spherically symmetric,
naked singularity spacetime, without a photon sphere. The nature of the
singularity is found to be lightlike. We discuss the characteristic lensing
features of this naked singularity in the strong deflection limit. In spite of
the absence of a photon sphere in this spacetime, the bending angle of light
diverges, as it approaches the singularity. However, unlike black holes, it is
found that the nature of this divergence is nonlogarithmic, and we derive an
analytic formula for the same. Moreover, the relativistic rings produced due to
strong lensing by the singularity are found to be well separated from each
other, making them easy to resolve and possibly detect. These features are
expected to be important in the study of strong lensing by ultracompact
objects, especially ones without event horizons.
| [
{
"created": "Fri, 10 Jul 2020 17:40:12 GMT",
"version": "v1"
},
{
"created": "Fri, 31 Jul 2020 05:32:25 GMT",
"version": "v2"
},
{
"created": "Thu, 24 Sep 2020 14:41:54 GMT",
"version": "v3"
}
] | 2020-09-25 | [
[
"Paul",
"Suvankar",
""
]
] | We study strong gravitational lensing in a static, spherically symmetric, naked singularity spacetime, without a photon sphere. The nature of the singularity is found to be lightlike. We discuss the characteristic lensing features of this naked singularity in the strong deflection limit. In spite of the absence of a photon sphere in this spacetime, the bending angle of light diverges, as it approaches the singularity. However, unlike black holes, it is found that the nature of this divergence is nonlogarithmic, and we derive an analytic formula for the same. Moreover, the relativistic rings produced due to strong lensing by the singularity are found to be well separated from each other, making them easy to resolve and possibly detect. These features are expected to be important in the study of strong lensing by ultracompact objects, especially ones without event horizons. |
1904.00419 | Eleni-Alexandra Kontou | P. J. Brown, C. J. Fewster and E.-A. Kontou | Classical and quantum strong energy inequalities and the Hawking
singularity theorem | 15th Marcel Grossmann conference proceedings, 6 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Hawking's singularity theorem concerns matter obeying the strong energy
condition (SEC), which means that all observers experience a non-negative
effective energy density (EED). The SEC ensures the timelike convergence
property. However, for both classical and quantum fields, violations of the SEC
can be observed even in the simplest of cases, like the Klein-Gordon field.
Therefore there is a need to develop theorems with weaker restrictions, namely
energy conditions averaged over an entire geodesic and weighted local averages
of energy densities such as quantum energy inequalities (QEIs). We present
lower bounds of the EED for both classical and quantum scalar fields allowing
nonzero mass and nonminimal coupling to the scalar curvature. In the quantum
case these bounds take the form of a set of state-dependent QEIs valid for the
class of Hadamard states. We also discuss how these lower bounds are applied to
prove Hawking-type singularity theorems asserting that, along with sufficient
initial contraction, the spacetime is future timelike geodesically incomplete.
| [
{
"created": "Sun, 31 Mar 2019 14:26:52 GMT",
"version": "v1"
}
] | 2019-04-02 | [
[
"Brown",
"P. J.",
""
],
[
"Fewster",
"C. J.",
""
],
[
"Kontou",
"E. -A.",
""
]
] | Hawking's singularity theorem concerns matter obeying the strong energy condition (SEC), which means that all observers experience a non-negative effective energy density (EED). The SEC ensures the timelike convergence property. However, for both classical and quantum fields, violations of the SEC can be observed even in the simplest of cases, like the Klein-Gordon field. Therefore there is a need to develop theorems with weaker restrictions, namely energy conditions averaged over an entire geodesic and weighted local averages of energy densities such as quantum energy inequalities (QEIs). We present lower bounds of the EED for both classical and quantum scalar fields allowing nonzero mass and nonminimal coupling to the scalar curvature. In the quantum case these bounds take the form of a set of state-dependent QEIs valid for the class of Hadamard states. We also discuss how these lower bounds are applied to prove Hawking-type singularity theorems asserting that, along with sufficient initial contraction, the spacetime is future timelike geodesically incomplete. |
2004.02446 | Zahra Safari | Z. Safari (1), B. Malekolkalami (2), H. Moshafi (3) ((1) Department of
Physics, University of Kurdistan, (2) Department of Physics, University of
Kurdistan, (3) Ibn-Sina Laboratory, Shahid Beheshti University) | Cosmological constraints on dark matter particle production rate | 16 pages, 7 figures, 1 table | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational particle production has been investigated by using Einstein's
gravitational field equations in the presence of a cosmological constant. To
study the mechanism of particle creation, the Universe has been considered as a
thermodynamics system and non-equilibrium thermodynamics has been employed. In
order to estimate the cosmological parameters with observational data,
including SNe Ia, BAO, Planck 2015 and HST, we have chosen a phenomenological
approach for the rate of particle creation. A non-zero particle production rate
was obtained implying that the possibility of the particle production is
consistent with recent cosmological observations. In the 1 sigma confidence
interval, the ratio of Gamma/3H0 was obtained to be 0.0835.
| [
{
"created": "Mon, 6 Apr 2020 07:42:50 GMT",
"version": "v1"
}
] | 2020-04-07 | [
[
"Safari",
"Z.",
""
],
[
"Malekolkalami",
"B.",
""
],
[
"Moshafi",
"H.",
""
]
] | Gravitational particle production has been investigated by using Einstein's gravitational field equations in the presence of a cosmological constant. To study the mechanism of particle creation, the Universe has been considered as a thermodynamics system and non-equilibrium thermodynamics has been employed. In order to estimate the cosmological parameters with observational data, including SNe Ia, BAO, Planck 2015 and HST, we have chosen a phenomenological approach for the rate of particle creation. A non-zero particle production rate was obtained implying that the possibility of the particle production is consistent with recent cosmological observations. In the 1 sigma confidence interval, the ratio of Gamma/3H0 was obtained to be 0.0835. |
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