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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0806.0402 | Sourav Sur | Saurya Das (Lethbridge U.), S. Shankaranarayanan (Portsmouth U., ICG),
Sourav Sur (Lethbridge U.) | Black hole entropy from entanglement: A review | Invited Review. To appear in the edited book: Classical and Quantum
Gravity Research Progress, Nova Publishers (2008).
https://www.novapublishers.com/catalog/product_info.php?products_id=9063 | Horizons in World Physics, Volume 268 (2009) Editors: Michael
Everett and Louis Pedroza | null | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We review aspects of the thermodynamics of black holes and in particular take
into account the fact that the quantum entanglement between the degrees of
freedom of a scalar field, traced inside the event horizon, can be the origin
of black hole entropy. The main reason behind such a plausibility is that the
well-known Bekenstein-Hawking entropy-area proportionality -- the so-called
`area law' of black hole physics -- holds for entanglement entropy as well,
provided the scalar field is in its ground state, or in other minimum
uncertainty states, such as a generic coherent state or squeezed state.
However, when the field is either in an excited state or in a state which is a
superposition of ground and excited states, a power-law correction to the area
law is shown to exist. Such a correction term falls off with increasing area,
so that eventually the area law is recovered for large enough horizon area. On
ascertaining the location of the microscopic degrees of freedom that lead to
the entanglement entropy of black holes, it is found that although the degrees
of freedom close to the horizon contribute most to the total entropy, the
contributions from those that are far from the horizon are more significant for
excited/superposed states than for the ground state. Thus, the deviations from
the area law for excited/superposed states may, in a way, be attributed to the
far-away degrees of freedom. Finally, taking the scalar field (which is traced
over) to be massive, we explore the changes on the area law due to the mass.
Although most of our computations are done in flat space-time with a
hypothetical spherical region, considered to be the analogue of the horizon, we
show that our results hold as well in curved space-times representing static
asymptotically flat spherical black holes with single horizon.
| [
{
"created": "Mon, 2 Jun 2008 22:48:05 GMT",
"version": "v1"
}
] | 2016-07-28 | [
[
"Das",
"Saurya",
"",
"Lethbridge U."
],
[
"Shankaranarayanan",
"S.",
"",
"Portsmouth U., ICG"
],
[
"Sur",
"Sourav",
"",
"Lethbridge U."
]
] | We review aspects of the thermodynamics of black holes and in particular take into account the fact that the quantum entanglement between the degrees of freedom of a scalar field, traced inside the event horizon, can be the origin of black hole entropy. The main reason behind such a plausibility is that the well-known Bekenstein-Hawking entropy-area proportionality -- the so-called `area law' of black hole physics -- holds for entanglement entropy as well, provided the scalar field is in its ground state, or in other minimum uncertainty states, such as a generic coherent state or squeezed state. However, when the field is either in an excited state or in a state which is a superposition of ground and excited states, a power-law correction to the area law is shown to exist. Such a correction term falls off with increasing area, so that eventually the area law is recovered for large enough horizon area. On ascertaining the location of the microscopic degrees of freedom that lead to the entanglement entropy of black holes, it is found that although the degrees of freedom close to the horizon contribute most to the total entropy, the contributions from those that are far from the horizon are more significant for excited/superposed states than for the ground state. Thus, the deviations from the area law for excited/superposed states may, in a way, be attributed to the far-away degrees of freedom. Finally, taking the scalar field (which is traced over) to be massive, we explore the changes on the area law due to the mass. Although most of our computations are done in flat space-time with a hypothetical spherical region, considered to be the analogue of the horizon, we show that our results hold as well in curved space-times representing static asymptotically flat spherical black holes with single horizon. |
2110.04867 | Giulia Gubitosi | Angel Ballesteros, Giulia Gubitosi, Flavio Mercati | Interplay between spacetime curvature, speed of light and quantum
deformations of relativistic symmetries | v2 matches the version accepted for publication. We added a few
references and comments, plus fixed some typos. v3 includes a few additional
references | Symmetry 2021, 13, 2099 | 10.3390/sym13112099 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recent work showed that $\kappa$-deformations can describe the quantum
deformation of several relativistic models that have been proposed in the
context of quantum gravity phenomenology. Starting from the Poincar\'e algebra
of special-relativistic symmetries, one can toggle the curvature parameter
$\Lambda$, the Planck scale quantum deformation parameter $\kappa$ and the
speed of light parameter $c$ to move to the well-studied $\kappa$-Poincar\'e
algebra, the (quantum) (A)dS algebra, the (quantum) Galilei and Carroll
algebras and their curved versions. In this review, we survey the properties
and relations of these algebras of relativistic symmetries and their associated
noncommutative spacetimes, emphasizing the nontrivial effects of interplay
between curvature, quantum deformation and speed of light parameters.
| [
{
"created": "Sun, 10 Oct 2021 17:57:57 GMT",
"version": "v1"
},
{
"created": "Mon, 1 Nov 2021 19:10:54 GMT",
"version": "v2"
},
{
"created": "Sun, 23 Jan 2022 19:12:12 GMT",
"version": "v3"
}
] | 2022-02-01 | [
[
"Ballesteros",
"Angel",
""
],
[
"Gubitosi",
"Giulia",
""
],
[
"Mercati",
"Flavio",
""
]
] | Recent work showed that $\kappa$-deformations can describe the quantum deformation of several relativistic models that have been proposed in the context of quantum gravity phenomenology. Starting from the Poincar\'e algebra of special-relativistic symmetries, one can toggle the curvature parameter $\Lambda$, the Planck scale quantum deformation parameter $\kappa$ and the speed of light parameter $c$ to move to the well-studied $\kappa$-Poincar\'e algebra, the (quantum) (A)dS algebra, the (quantum) Galilei and Carroll algebras and their curved versions. In this review, we survey the properties and relations of these algebras of relativistic symmetries and their associated noncommutative spacetimes, emphasizing the nontrivial effects of interplay between curvature, quantum deformation and speed of light parameters. |
1203.5212 | Alexander Gorbatsievich | Alexander Gorbatsievich and Ernst Schmutzer | Field Equations and Equations of Motion in Post-Newtonian Approximation
of the Projective Unified Field Theory | 17 pages | International Journal of Modern Physics E (IJMPE), Volume: 21,
Issue: 2(2012) 1250012 | 10.1142/S0218301312500127 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The equations of motion of $N$ gravitationally bound bodies are derived from
the field equations of Projective Unified Field Theory. The Newtonian and the
post-Newtonian approximations of the field equations and of the equations of
motion of this system of bodies are studied in detail. In analyzing some
experimental data we performed some numeric estimates of the ratio of the
inertial mass to the scalaric mass of matter.
| [
{
"created": "Fri, 23 Mar 2012 11:08:32 GMT",
"version": "v1"
},
{
"created": "Thu, 17 May 2012 10:29:55 GMT",
"version": "v2"
}
] | 2012-05-18 | [
[
"Gorbatsievich",
"Alexander",
""
],
[
"Schmutzer",
"Ernst",
""
]
] | The equations of motion of $N$ gravitationally bound bodies are derived from the field equations of Projective Unified Field Theory. The Newtonian and the post-Newtonian approximations of the field equations and of the equations of motion of this system of bodies are studied in detail. In analyzing some experimental data we performed some numeric estimates of the ratio of the inertial mass to the scalaric mass of matter. |
2105.13658 | Nikolaos Dimakis | Theodoros Pailas, N. Dimakis, Petros A. Terzis and Theodosios
Christodoulakis | Time-covariant Schr\"{o}dinger equation and invariant decay probability:
The $\Lambda$-Kantowski-Sachs universe | Latex2e source file, 21 pages, no figures, minor changes to match
published version | null | 10.1140/epjc/s10052-021-09866-3 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The system under study is the $\Lambda$-Kantowski-Sachs universe. Its
canonical quantization is provided based on a recently developed method: the
singular minisuperspace Lagrangian describing the system, is reduced to a
regular (by inserting into the dynamical equations the lapse dictated by the
quadratic constraint) possessing an explicit (though arbitrary) time
dependence; thus a time-covariant Schr\"{o}dinger equation arises.
Additionally, an invariant (under transformations $t=f(\tilde{t})$) decay
probability is defined and thus ``observers'' which correspond to different
gauge choices obtain, by default, the same results. The time of decay for a
Gaussian wave packet localized around the point $a=0$ (where $a$ the radial
scale factor) is calculated to be of the order $\sim
10^{-42}-10^{-41}\mathrm{s}$. The acquired value is near the end of the Planck
era (when comparing to a FLRW universe), during which the quantum effects are
most prominent. Some of the results are compared to those obtained by following
the well known canonical quantization of cosmological systems, i.e. the
solutions of the Wheeler-DeWitt equation.
| [
{
"created": "Fri, 28 May 2021 08:09:35 GMT",
"version": "v1"
},
{
"created": "Mon, 22 Nov 2021 02:51:02 GMT",
"version": "v2"
},
{
"created": "Wed, 1 Dec 2021 08:43:00 GMT",
"version": "v3"
}
] | 2021-12-22 | [
[
"Pailas",
"Theodoros",
""
],
[
"Dimakis",
"N.",
""
],
[
"Terzis",
"Petros A.",
""
],
[
"Christodoulakis",
"Theodosios",
""
]
] | The system under study is the $\Lambda$-Kantowski-Sachs universe. Its canonical quantization is provided based on a recently developed method: the singular minisuperspace Lagrangian describing the system, is reduced to a regular (by inserting into the dynamical equations the lapse dictated by the quadratic constraint) possessing an explicit (though arbitrary) time dependence; thus a time-covariant Schr\"{o}dinger equation arises. Additionally, an invariant (under transformations $t=f(\tilde{t})$) decay probability is defined and thus ``observers'' which correspond to different gauge choices obtain, by default, the same results. The time of decay for a Gaussian wave packet localized around the point $a=0$ (where $a$ the radial scale factor) is calculated to be of the order $\sim 10^{-42}-10^{-41}\mathrm{s}$. The acquired value is near the end of the Planck era (when comparing to a FLRW universe), during which the quantum effects are most prominent. Some of the results are compared to those obtained by following the well known canonical quantization of cosmological systems, i.e. the solutions of the Wheeler-DeWitt equation. |
1704.08794 | Jiliang Jing | Jiliang Jing, Songbai Chen, Qiyuan Pan, Jieci Wang | Detect black holes using photons for coupling model of electromagnetic
and gravitational fields | 15 pages | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | For a model of the electromagnetic field coupled to Weyl tensor, Maxwell
equations are modified and photons at low frequencies no longer propagate along
light cone. If we detect a black hole using these photons, some difficulties
appear because we can not determine the position of event horizon which is
defined by null surface. To overcome these difficulties, the simplest way may
be an effective description by introducing an effective spacetime in which the
photons propagate along the light cone. Then, we find, comparing the results
with those of the original spacetime, that the event horizon and temperature do
not change, but the area of the event horizon and Bekenstein-Hawking entropy
become different. We show that the total entropy for this system, which is
still the same as that of original spacetime, consists of two parts, one is the
Bekenstein-Hawking entropy and the other is the entropy arising from the
coupling of electromagnetic field and Weyl tensor. We also present the
effective descriptions for the Smarr relation and first law of thermodynamics.
| [
{
"created": "Fri, 28 Apr 2017 02:57:44 GMT",
"version": "v1"
}
] | 2017-05-01 | [
[
"Jing",
"Jiliang",
""
],
[
"Chen",
"Songbai",
""
],
[
"Pan",
"Qiyuan",
""
],
[
"Wang",
"Jieci",
""
]
] | For a model of the electromagnetic field coupled to Weyl tensor, Maxwell equations are modified and photons at low frequencies no longer propagate along light cone. If we detect a black hole using these photons, some difficulties appear because we can not determine the position of event horizon which is defined by null surface. To overcome these difficulties, the simplest way may be an effective description by introducing an effective spacetime in which the photons propagate along the light cone. Then, we find, comparing the results with those of the original spacetime, that the event horizon and temperature do not change, but the area of the event horizon and Bekenstein-Hawking entropy become different. We show that the total entropy for this system, which is still the same as that of original spacetime, consists of two parts, one is the Bekenstein-Hawking entropy and the other is the entropy arising from the coupling of electromagnetic field and Weyl tensor. We also present the effective descriptions for the Smarr relation and first law of thermodynamics. |
1205.3929 | Ran Li | Ran Li | Superradiant instability of charged massive scalar field in
Kerr-Newman-anti-de Sitter black hole | 13 pages, no figure, comments are welcome! Revised version accepted
by PLB | Phys. Lett. B 714 (2012) 337-341 | 10.1016/j.physletb.2012.07.015 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the superradiance instability of charged massive scalar field in the
background of Kerr-Newman-anti-de Sitter black hole. By employing the
asymptotic matching technique to solve Klein-Gordon equation analytically, the
complex parts of quasinormal frequencies are shown to be positive in the regime
of superradiance. Because the calculation is performed in the approximation of
small black hole, the result indicates that small Kerr-Newman-anti-de Sitter
black hole is unstable against the massive scalar field perturbation with small
charge.
| [
{
"created": "Thu, 17 May 2012 13:42:53 GMT",
"version": "v1"
},
{
"created": "Sat, 7 Jul 2012 01:00:26 GMT",
"version": "v2"
}
] | 2012-07-31 | [
[
"Li",
"Ran",
""
]
] | We study the superradiance instability of charged massive scalar field in the background of Kerr-Newman-anti-de Sitter black hole. By employing the asymptotic matching technique to solve Klein-Gordon equation analytically, the complex parts of quasinormal frequencies are shown to be positive in the regime of superradiance. Because the calculation is performed in the approximation of small black hole, the result indicates that small Kerr-Newman-anti-de Sitter black hole is unstable against the massive scalar field perturbation with small charge. |
2012.03416 | Daniel Flores | Daniel Flores-Alfonso, Rom\'an Linares, Marco Maceda | Nonlinear extensions of gravitating dyons: from NUT wormholes to
Taub-Bolt instantons | null | JHEP 09 (2021) 104 | 10.1007/JHEP09(2021)104 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | Recent work has shown the existence of a unique nonlinear extension of
electromagnetism which preserves conformal symmetry and allows for the freedom
of duality rotations. Moreover, black holes and gravitational waves have been
found to exist in this nonlinearly extended electrovacuum. We generalise these
dyonic black holes in two major ways: with the relaxation of their horizon
topology and with the inclusion of magnetic mass. Motivated by recent attention
to traversable wormholes, we use this new family of Taub-NUT spaces to
construct AdS wormholes. We explore some thermodynamic features by using a
semi-classical approach. Our results show that a phase transition between the
nut and bolt configurations arises in a similar way to the Maxwellian case.
| [
{
"created": "Mon, 7 Dec 2020 02:10:49 GMT",
"version": "v1"
},
{
"created": "Fri, 16 Jul 2021 00:35:00 GMT",
"version": "v2"
},
{
"created": "Sat, 18 Sep 2021 04:10:02 GMT",
"version": "v3"
}
] | 2021-09-21 | [
[
"Flores-Alfonso",
"Daniel",
""
],
[
"Linares",
"Román",
""
],
[
"Maceda",
"Marco",
""
]
] | Recent work has shown the existence of a unique nonlinear extension of electromagnetism which preserves conformal symmetry and allows for the freedom of duality rotations. Moreover, black holes and gravitational waves have been found to exist in this nonlinearly extended electrovacuum. We generalise these dyonic black holes in two major ways: with the relaxation of their horizon topology and with the inclusion of magnetic mass. Motivated by recent attention to traversable wormholes, we use this new family of Taub-NUT spaces to construct AdS wormholes. We explore some thermodynamic features by using a semi-classical approach. Our results show that a phase transition between the nut and bolt configurations arises in a similar way to the Maxwellian case. |
1911.05459 | Masoud Ghezelbash | M. F. A. R. Sakti, A. M. Ghezelbash, A. Suroso, F. P. Zen | Deformed conformal symmetry of Kerr-Newman-NUT-AdS black holes | 19 pages | Gen. Relativ. Gravit. (2019) 51:151 | 10.1007/s10714-019-2641-z | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We find generators of the conformal symmetry for the class of
Kerr-Newman-NUT-AdS black holes from the deformed scalar probe equation. We
find two classes of solutions for the generators (also known as conformal J and
Q pictures). The two classes of deformed generators are the extension of
similar generators for the regular conformal symmetry. Moreover, we find that
the two pictures can be generalized and extended into a general picture. In
each picture, the generators produce an extended local family of SL(2,R)_L
\times SL(2,R)_R hidden conformal symmetries for the Kerr-Newman-NUT-AdS black
holes which are parameterized by one deformation parameter. We find the
absorption cross-section of the scalar probes for the Kerr-Newman-NUT-AdS black
holes, which in turn, supports the existence of Kerr/CFT correspondence.
Moreover, our deformed conformal generators for the Kerr-Newman-NUT-AdS black
holes provide the deformed conformal generators for the non-rotating
Reissner-Nordstrom-NUT-AdS black holes.
| [
{
"created": "Wed, 13 Nov 2019 13:48:54 GMT",
"version": "v1"
}
] | 2020-01-06 | [
[
"Sakti",
"M. F. A. R.",
""
],
[
"Ghezelbash",
"A. M.",
""
],
[
"Suroso",
"A.",
""
],
[
"Zen",
"F. P.",
""
]
] | We find generators of the conformal symmetry for the class of Kerr-Newman-NUT-AdS black holes from the deformed scalar probe equation. We find two classes of solutions for the generators (also known as conformal J and Q pictures). The two classes of deformed generators are the extension of similar generators for the regular conformal symmetry. Moreover, we find that the two pictures can be generalized and extended into a general picture. In each picture, the generators produce an extended local family of SL(2,R)_L \times SL(2,R)_R hidden conformal symmetries for the Kerr-Newman-NUT-AdS black holes which are parameterized by one deformation parameter. We find the absorption cross-section of the scalar probes for the Kerr-Newman-NUT-AdS black holes, which in turn, supports the existence of Kerr/CFT correspondence. Moreover, our deformed conformal generators for the Kerr-Newman-NUT-AdS black holes provide the deformed conformal generators for the non-rotating Reissner-Nordstrom-NUT-AdS black holes. |
2401.04467 | Chao Zhang | Chao Zhang, Guoyang Fu and Ning Dai | Detecting dark matter with extreme mass-ratio inspirals | 17 pages, 5 figures, 2 tables; comments are welcome | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Extreme mass ratio inspirals (EMRIs), where a small compact object inspiralls
onto a supermassive black hole, are excellent sources for the space-based laser
interferometer gravitational wave (GW) detectors. The presence of dark matter
surrounding the supermassive black hole will influence the binary orbital
evolution and emitted gravitational waveform. By direct observation of GW
signals, we assess the detector's capability to detect whether an EMRI is
immersed in a dark matter halo and to measure its characteristic spatial scale
$a_0$ and mass $M_{\rm halo}$. Apart from the GW emission, the dynamical
friction and accretion caused by the dark matter halo can also affect the
dynamics of an EMRI, leaving detectable signatures in the emitted gravitational
signal. We perform a Fisher-matrix error analysis to estimate the errors of
parameters $a_0$ and $M_{\rm halo}$, as well as their correlation. The results
show that the highly correlated parameters $a_0$ and $M_{\rm halo}$ deteriorate
the detector's ability to measure dark matter even though the dephasing and
mismatch between signals with and without dark matter indicate much difference.
The effects of the dynamical friction and accretion can break possible
degeneracies between parameters $a_0$ and $M_{\rm halo}$, thus greatly
decreasing the uncertainty by about one order of magnitude.
| [
{
"created": "Tue, 9 Jan 2024 10:08:38 GMT",
"version": "v1"
}
] | 2024-01-10 | [
[
"Zhang",
"Chao",
""
],
[
"Fu",
"Guoyang",
""
],
[
"Dai",
"Ning",
""
]
] | Extreme mass ratio inspirals (EMRIs), where a small compact object inspiralls onto a supermassive black hole, are excellent sources for the space-based laser interferometer gravitational wave (GW) detectors. The presence of dark matter surrounding the supermassive black hole will influence the binary orbital evolution and emitted gravitational waveform. By direct observation of GW signals, we assess the detector's capability to detect whether an EMRI is immersed in a dark matter halo and to measure its characteristic spatial scale $a_0$ and mass $M_{\rm halo}$. Apart from the GW emission, the dynamical friction and accretion caused by the dark matter halo can also affect the dynamics of an EMRI, leaving detectable signatures in the emitted gravitational signal. We perform a Fisher-matrix error analysis to estimate the errors of parameters $a_0$ and $M_{\rm halo}$, as well as their correlation. The results show that the highly correlated parameters $a_0$ and $M_{\rm halo}$ deteriorate the detector's ability to measure dark matter even though the dephasing and mismatch between signals with and without dark matter indicate much difference. The effects of the dynamical friction and accretion can break possible degeneracies between parameters $a_0$ and $M_{\rm halo}$, thus greatly decreasing the uncertainty by about one order of magnitude. |
2010.01399 | David Garfinkle | David Garfinkle and Frans Pretorius | Spike behavior in the approach to spacetime singularities | null | Phys. Rev. D 102, 124067 (2020) | 10.1103/PhysRevD.102.124067 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We perform numerical simulations of the approach to spacetime singularities.
The simulations are done with sufficient resolution to resolve the small scale
features (known as spikes) that form in this process. We find an analytical
formula for the shape of the spikes and show that the spikes in the simulations
are well described by this formula.
| [
{
"created": "Sat, 3 Oct 2020 17:48:13 GMT",
"version": "v1"
}
] | 2021-01-04 | [
[
"Garfinkle",
"David",
""
],
[
"Pretorius",
"Frans",
""
]
] | We perform numerical simulations of the approach to spacetime singularities. The simulations are done with sufficient resolution to resolve the small scale features (known as spikes) that form in this process. We find an analytical formula for the shape of the spikes and show that the spikes in the simulations are well described by this formula. |
gr-qc/9505046 | Paula Bozzay | E. Calzetta and B. L. Hu | Quantum Fluctuations, Decoherence of the Mean Field, and Structure
Formation in the Early Universe | 35 pages, latex, 0 figures | Phys.Rev.D52:6770-6788,1995 | 10.1103/PhysRevD.52.6770 | IASSNS-HEP-95/38 | gr-qc | null | We examine from first principles one of the basic assumptions of modern
quantum theories of structure formation in the early universe, i.e., the
conditions upon which fluctuations of a quantum field may transmute into
classical stochastic perturbations, which grew into galaxies. Our earlier works
have discussed the quantum origin of noise in stochastic inflation and quantum
fluctuations as measured by particle creation in semiclassical gravity. Here we
focus on decoherence and the relation of quantum and classical fluctuations.
Instead of using the rather ad hoc splitting of a quantum field into long and
short wavelength parts, the latter providing the noise which decoheres the
former, we treat a nonlinear theory and examine the decoherence of a quantum
mean field by its own quantum fluctuations, or that of other fields it
interacts with. This is an example of `dynamical decoherence' where an
effective open quantum system decoheres through its own dynamics. The model we
use to discuss fluctuation generation has the inflation field coupled to the
graviton field. We show that when the quantum to classical transition is
properly treated, with due consideration of the relation of decoherence, noise,
fluctuation and dissipation, the amplitude of density contrast predicted falls
in the acceptable range without requiring a fine tuning of the coupling
constant of the inflation field ($\lambda$). The conventional treatment which
requires an unnaturally small $\lambda \approx 10^{-12}$ stems from a basic
flaw in naively identifying classical perturbations with quantum fluctuations.
| [
{
"created": "Wed, 24 May 1995 18:05:00 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Calzetta",
"E.",
""
],
[
"Hu",
"B. L.",
""
]
] | We examine from first principles one of the basic assumptions of modern quantum theories of structure formation in the early universe, i.e., the conditions upon which fluctuations of a quantum field may transmute into classical stochastic perturbations, which grew into galaxies. Our earlier works have discussed the quantum origin of noise in stochastic inflation and quantum fluctuations as measured by particle creation in semiclassical gravity. Here we focus on decoherence and the relation of quantum and classical fluctuations. Instead of using the rather ad hoc splitting of a quantum field into long and short wavelength parts, the latter providing the noise which decoheres the former, we treat a nonlinear theory and examine the decoherence of a quantum mean field by its own quantum fluctuations, or that of other fields it interacts with. This is an example of `dynamical decoherence' where an effective open quantum system decoheres through its own dynamics. The model we use to discuss fluctuation generation has the inflation field coupled to the graviton field. We show that when the quantum to classical transition is properly treated, with due consideration of the relation of decoherence, noise, fluctuation and dissipation, the amplitude of density contrast predicted falls in the acceptable range without requiring a fine tuning of the coupling constant of the inflation field ($\lambda$). The conventional treatment which requires an unnaturally small $\lambda \approx 10^{-12}$ stems from a basic flaw in naively identifying classical perturbations with quantum fluctuations. |
0903.3256 | Ricardo Monteiro | Ricardo Monteiro, Malcolm J. Perry, Jorge E. Santos | Thermodynamic instability of rotating black holes | 36 pages, 11 figures; v2: corrections to match published version | Phys.Rev.D80:024041,2009 | 10.1103/PhysRevD.80.024041 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that the quasi-Euclidean sections of various rotating black holes in
different dimensions possess at least one non-conformal negative mode when
thermodynamic instabilities are expected. The boundary conditions of fixed
induced metric correspond to the partition function of the grand-canonical
ensemble. Indeed, in the asymptotically flat cases, we find that a negative
mode persists even if the specific heat at constant angular momenta is
positive, since the stability in this ensemble also requires the positivity of
the isothermal momentum of inertia. We focus in particular on Kerr black holes,
on Myers-Perry black holes in five and six dimensions, and on the Emparan-Reall
black ring solution. We go on further to consider the richer case of the
asymptotically AdS Kerr black hole in four dimensions, where thermodynamic
stability is expected for a large enough cosmological constant. The results are
consistent with previous findings in the non-rotation limit and support the use
of quasi-Euclidean instantons to construct gravitational partition functions.
| [
{
"created": "Wed, 18 Mar 2009 23:39:53 GMT",
"version": "v1"
},
{
"created": "Thu, 30 Jul 2009 17:52:52 GMT",
"version": "v2"
}
] | 2010-04-14 | [
[
"Monteiro",
"Ricardo",
""
],
[
"Perry",
"Malcolm J.",
""
],
[
"Santos",
"Jorge E.",
""
]
] | We show that the quasi-Euclidean sections of various rotating black holes in different dimensions possess at least one non-conformal negative mode when thermodynamic instabilities are expected. The boundary conditions of fixed induced metric correspond to the partition function of the grand-canonical ensemble. Indeed, in the asymptotically flat cases, we find that a negative mode persists even if the specific heat at constant angular momenta is positive, since the stability in this ensemble also requires the positivity of the isothermal momentum of inertia. We focus in particular on Kerr black holes, on Myers-Perry black holes in five and six dimensions, and on the Emparan-Reall black ring solution. We go on further to consider the richer case of the asymptotically AdS Kerr black hole in four dimensions, where thermodynamic stability is expected for a large enough cosmological constant. The results are consistent with previous findings in the non-rotation limit and support the use of quasi-Euclidean instantons to construct gravitational partition functions. |
1901.07545 | Vladimir Dzhunushaliev | Vladimir Dzhunushaliev, Vladimir Folomeev, Burkhard Kleihaus and Jutta
Kunz | Thin-shell toroidal wormhole | 7 pages, 1 figure | Phys. Rev. D 99, 044031 (2019) | 10.1103/PhysRevD.99.044031 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a topologically nontrivial thin-shell wormhole with a throat in
the form of a $T^2$ torus. It is shown that: (i)~such a wormhole is stable with
respect to excitations of the throat; (ii)~not all energy conditions are
violated for such wormholes; (iii)~if any of the energy conditions is violated,
this violation occurs only partially in some region near the throat, and in
other regions the violation is absent. Also, we discuss the differences between
spherical $S^2$ wormholes and toroidal $T^2$ wormholes under investigation.
| [
{
"created": "Tue, 22 Jan 2019 05:58:28 GMT",
"version": "v1"
},
{
"created": "Mon, 28 Jan 2019 11:02:21 GMT",
"version": "v2"
}
] | 2019-02-27 | [
[
"Dzhunushaliev",
"Vladimir",
""
],
[
"Folomeev",
"Vladimir",
""
],
[
"Kleihaus",
"Burkhard",
""
],
[
"Kunz",
"Jutta",
""
]
] | We consider a topologically nontrivial thin-shell wormhole with a throat in the form of a $T^2$ torus. It is shown that: (i)~such a wormhole is stable with respect to excitations of the throat; (ii)~not all energy conditions are violated for such wormholes; (iii)~if any of the energy conditions is violated, this violation occurs only partially in some region near the throat, and in other regions the violation is absent. Also, we discuss the differences between spherical $S^2$ wormholes and toroidal $T^2$ wormholes under investigation. |
0906.3315 | Fernando P. Devecchi | L. L. Samojeden, G. M. Kremer and F. P. Devecchi | Accelerated expansion in bosonic and fermionic 2D cosmologies with
quantum effects | 6 pages, 5 figures, to appear in EPL | Europhys.Lett.87:10001,2009 | 10.1209/0295-5075/87/10001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we analyze the effects produced by bosonic and fermionic
constituents, including quantum corrections, in two-dimensional (2D)
cosmological models. We focus on a gravitational theory related to the
Callan-Giddings-Harvey-Strominger model, to simulate the dynamics of a young,
spatially-lineal, universe. The cosmic substratum is formed by an {\it
inflaton} field plus a matter component, sources of the 2D gravitational field;
the degrees of freedom also include the presence of a dilaton field. We show
that this combination permits, among other scenarios, the simulation of a
period of inflation, that would be followed by a (bosonic/fermionic) matter
dominated era. We also analyse how quantum effects contribute to the destiny of
the expansion, given the fact that in 2D we have a consistent (renormalizable)
quantum theory of gravity. The dynamical behavior of the system follows from
the solution of the gravitational field equations, the (Klein-Gordon and Dirac)
equations for the sources and the dilaton field equation. Consistent
(accelerated) regimes are present among the solutions of the 2D equations; the
results depend strongly on the initial conditions used for the dilaton field.
In the particular case where fermions are included as matter fields a
transition to a decelerated expansion is possible, something that does not
happen in the exclusively bosonic case.
| [
{
"created": "Wed, 17 Jun 2009 21:40:47 GMT",
"version": "v1"
}
] | 2009-08-07 | [
[
"Samojeden",
"L. L.",
""
],
[
"Kremer",
"G. M.",
""
],
[
"Devecchi",
"F. P.",
""
]
] | In this work we analyze the effects produced by bosonic and fermionic constituents, including quantum corrections, in two-dimensional (2D) cosmological models. We focus on a gravitational theory related to the Callan-Giddings-Harvey-Strominger model, to simulate the dynamics of a young, spatially-lineal, universe. The cosmic substratum is formed by an {\it inflaton} field plus a matter component, sources of the 2D gravitational field; the degrees of freedom also include the presence of a dilaton field. We show that this combination permits, among other scenarios, the simulation of a period of inflation, that would be followed by a (bosonic/fermionic) matter dominated era. We also analyse how quantum effects contribute to the destiny of the expansion, given the fact that in 2D we have a consistent (renormalizable) quantum theory of gravity. The dynamical behavior of the system follows from the solution of the gravitational field equations, the (Klein-Gordon and Dirac) equations for the sources and the dilaton field equation. Consistent (accelerated) regimes are present among the solutions of the 2D equations; the results depend strongly on the initial conditions used for the dilaton field. In the particular case where fermions are included as matter fields a transition to a decelerated expansion is possible, something that does not happen in the exclusively bosonic case. |
1711.06255 | Sergey Yu. Vernov | E.O. Pozdeeva and S.Yu. Vernov | Induced gravity models with exact bounce solutions | 6 pages | Phys. Part. Nuclei 49 (2018) 914 | 10.1134/S1063779618050337 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study dynamics of induced gravity cosmological models with the sixth
degree polynomial potentials, that have been constructed using the
superpotential method. We find conditions on the potential under which exact
bounce solutions exist and study the stability of these solutions.
| [
{
"created": "Thu, 16 Nov 2017 18:57:23 GMT",
"version": "v1"
}
] | 2018-10-22 | [
[
"Pozdeeva",
"E. O.",
""
],
[
"Vernov",
"S. Yu.",
""
]
] | We study dynamics of induced gravity cosmological models with the sixth degree polynomial potentials, that have been constructed using the superpotential method. We find conditions on the potential under which exact bounce solutions exist and study the stability of these solutions. |
1411.5486 | Christian Boehmer | Christian G. Boehmer, Matthew Wright | Slowly rotating perfect fluids with a cosmological constant | 19 pages, 2 figures | General Relativity and Gravitation 47 (2015) 143 | 10.1007/s10714-015-1982-5 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Hartle's slow rotation formalism is developed in the presence of a
cosmological constant. We find the generalisation of the Hartle-Thorne vacuum
metric, the Hartle-Thorne-(anti)-de Sitter metric, and find that it is always
asymptotically (anti)-de Sitter. Next we consider Wahlquist's rotating perfect
fluid interior solution in Hartle's formalism and discuss its matching to the
Hartle-Thorne-(anti)-de Sitter metric. It is known that the Wahlquist solution
cannot be matched to an asymptotically flat region and therefore does not
provide a model of an isolated rotating body in this context. However, in the
presence of a cosmological term, we find that it can be matched to an
asymptotic (anti)-de Sitter space and we are able to interpret the Wahlquist
solution as a model of an isolated rotating body, to second order in the
angular velocity.
| [
{
"created": "Thu, 20 Nov 2014 10:07:55 GMT",
"version": "v1"
}
] | 2015-11-12 | [
[
"Boehmer",
"Christian G.",
""
],
[
"Wright",
"Matthew",
""
]
] | Hartle's slow rotation formalism is developed in the presence of a cosmological constant. We find the generalisation of the Hartle-Thorne vacuum metric, the Hartle-Thorne-(anti)-de Sitter metric, and find that it is always asymptotically (anti)-de Sitter. Next we consider Wahlquist's rotating perfect fluid interior solution in Hartle's formalism and discuss its matching to the Hartle-Thorne-(anti)-de Sitter metric. It is known that the Wahlquist solution cannot be matched to an asymptotically flat region and therefore does not provide a model of an isolated rotating body in this context. However, in the presence of a cosmological term, we find that it can be matched to an asymptotic (anti)-de Sitter space and we are able to interpret the Wahlquist solution as a model of an isolated rotating body, to second order in the angular velocity. |
1805.06673 | Kaushik Bhattacharya | Pritha Bari, Kaushik Bhattacharya, Saikat Chakraborty | Early universe cosmological solutions in exponential gravity | 22 pages, 20 figures. Some new material on cosmological perturbation
is added and the introduction section has slightly been modified. Some new
figures are included. Accepted for publication in the special issue on
"Bounce Cosmology" in Universe-Open Access Journal of Theoretical Physics.
arXiv admin note: text overlap with arXiv:1610.00938 by other authors | null | null | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we present some cosmologically relevant solutions using the
spatially flat Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetime in metric
$f(R)$ gravity where the form of the gravitational Lagrangian is given by
$\frac{1}{\alpha}e^{\alpha R}$. In the low curvature limit this theory reduces
to ordinary Einstein-Hilbert Lagrangian together with a cosmological constant
term. Precisely because of this cosmological constant term this theory of
gravity is able to support nonsingular bouncing solutions in both matter and
vacuum background. Since for this theory of gravity $f^{\prime}$ and
$f^{\prime\prime}$ is always positive, this is free of both ghost instability
and tachyonic instability. Moreover, because of the existence of the
cosmological constant term, this gravity theory also admits a de-Sitter
solution. Lastly we hint towards the possibility of a new type of cosmological
solution that is possible only in higher derivative theories of gravity like
this one.
| [
{
"created": "Thu, 17 May 2018 09:49:48 GMT",
"version": "v1"
},
{
"created": "Thu, 11 Oct 2018 13:23:02 GMT",
"version": "v2"
}
] | 2018-10-17 | [
[
"Bari",
"Pritha",
""
],
[
"Bhattacharya",
"Kaushik",
""
],
[
"Chakraborty",
"Saikat",
""
]
] | In this work we present some cosmologically relevant solutions using the spatially flat Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetime in metric $f(R)$ gravity where the form of the gravitational Lagrangian is given by $\frac{1}{\alpha}e^{\alpha R}$. In the low curvature limit this theory reduces to ordinary Einstein-Hilbert Lagrangian together with a cosmological constant term. Precisely because of this cosmological constant term this theory of gravity is able to support nonsingular bouncing solutions in both matter and vacuum background. Since for this theory of gravity $f^{\prime}$ and $f^{\prime\prime}$ is always positive, this is free of both ghost instability and tachyonic instability. Moreover, because of the existence of the cosmological constant term, this gravity theory also admits a de-Sitter solution. Lastly we hint towards the possibility of a new type of cosmological solution that is possible only in higher derivative theories of gravity like this one. |
2107.06934 | Surajit Kalita | Surajit Kalita | Timescales for Detecting Magnetized White Dwarfs in Gravitational Wave
Astronomy | 6 pages with 4 figures; published in the proceedings of 1st
Electronic Conference on Universe, 22-28 February 2021 | Physical Sciences Forum (2021) 2(1), 12 | 10.3390/ECU2021-09310 | null | gr-qc astro-ph.HE astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Over the past couple of decades, researchers have predicted more than a dozen
super-Chandrasekhar white dwarfs from the detections of over-luminous type Ia
supernovae. It turns out that magnetic fields and rotation can explain such
massive white dwarfs. If these rotating magnetized white dwarfs follow specific
conditions, they can efficiently emit continuous gravitational waves and
various futuristic detectors, viz. LISA, BBO, DECIGO, and ALIA can detect such
gravitational waves with a significant signal-to-noise ratio. Moreover, we
discuss various timescales over which these white dwarfs can emit dipole and
quadrupole radiations and show that in the future, the gravitational wave
detectors can directly detect the super-Chandrasekhar white dwarfs depending on
the magnetic field geometry and its strength.
| [
{
"created": "Wed, 14 Jul 2021 18:37:45 GMT",
"version": "v1"
}
] | 2021-07-19 | [
[
"Kalita",
"Surajit",
""
]
] | Over the past couple of decades, researchers have predicted more than a dozen super-Chandrasekhar white dwarfs from the detections of over-luminous type Ia supernovae. It turns out that magnetic fields and rotation can explain such massive white dwarfs. If these rotating magnetized white dwarfs follow specific conditions, they can efficiently emit continuous gravitational waves and various futuristic detectors, viz. LISA, BBO, DECIGO, and ALIA can detect such gravitational waves with a significant signal-to-noise ratio. Moreover, we discuss various timescales over which these white dwarfs can emit dipole and quadrupole radiations and show that in the future, the gravitational wave detectors can directly detect the super-Chandrasekhar white dwarfs depending on the magnetic field geometry and its strength. |
0809.0304 | Juan Manuel Garcia-Islas | J.Manuel Garcia-Islas | Towards a spin foam model description of black hole entropy | 5 pages, 1 figure | Class.Quant.Grav.25:238001,2008 | 10.1088/0264-9381/25/23/238001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose a way to describe the origin of black hole entropy in the spin
foam models of quantum gravity. This stimulates a new way to study the relation
of spin foam models and loop quantum gravity.
| [
{
"created": "Mon, 1 Sep 2008 19:36:18 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Garcia-Islas",
"J. Manuel",
""
]
] | We propose a way to describe the origin of black hole entropy in the spin foam models of quantum gravity. This stimulates a new way to study the relation of spin foam models and loop quantum gravity. |
1901.04128 | Ming Zhang | Ming Zhang | Interior Volume of Banados-Teitelboim-Zanelli Black Hole | 6 pages | null | 10.1016/j.physletb.2019.01.032 | null | gr-qc hep-th | http://creativecommons.org/licenses/by-nc-sa/4.0/ | We calculate the interior volume for the three-dimensional
Banados-Teitelboim-Zanelli black hole in this paper. To that end, we obtain the
volume functional and numerically find a path to extremize it, before choosing
a spacelike hypersurface to get an asymptotic analytical expression for the
interior volume based on the characteristics of the path.
| [
{
"created": "Mon, 14 Jan 2019 04:55:42 GMT",
"version": "v1"
}
] | 2019-01-23 | [
[
"Zhang",
"Ming",
""
]
] | We calculate the interior volume for the three-dimensional Banados-Teitelboim-Zanelli black hole in this paper. To that end, we obtain the volume functional and numerically find a path to extremize it, before choosing a spacelike hypersurface to get an asymptotic analytical expression for the interior volume based on the characteristics of the path. |
2305.05793 | Daniel Oliver | Daniel J Oliver, Aaron D Johnson, Joel Berrier, Kostas Glampedakis,
Daniel Kennefick | Gravitational Wave Peeps from EMRIs and their Implication for LISA
Signal Confusion Noise | 18 pages, 13 figures | null | null | null | gr-qc astro-ph.GA | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Scattering events around a supermassive black hole will occasionally toss a
stellar-mass compact object into an orbit around the supermassive black hole,
beginning an extreme mass ratio inspiral. The early stages of such a highly
eccentric orbit will not produce detectable gravitational waves as the source
will only be in a suitable frequency band briefly when it is close to periapsis
during each long-period orbit. This burst of emission, firmly in the millihertz
band is the gravitational wave peep. While a single peep is not likely to be
detectable, if we consider an ensemble of such subthreshold sources, spread
across the universe, together they produce an unresolvable background noise
that may obscure sources otherwise detectable by the Laser Interferometer Space
Antenna, the proposed space-based gravitational wave detector. Previous studies
of the extreme mass ratio burst signal confusion background focused more on
parabolic orbits going very near the supermassive black hole and on events near
the galactic center. We seek to improve this characterization by implementing
numerical kludge waveforms that can calculate highly eccentric orbits with
relativistic effects focusing on orbits which are farther away from the
supermassive black hole and thus less likely to be detectable on their own, but
will otherwise contribute to the background signal confusion noise. Here we
present the waveforms and spectra of the gravitational wave peeps generated
from recent calculations of extreme mass ratio inspirals/bursts capture
parameters and discuss how these can be used to estimate the signal confusion
noise generated by such events.
| [
{
"created": "Tue, 9 May 2023 22:56:16 GMT",
"version": "v1"
},
{
"created": "Tue, 29 Aug 2023 18:29:55 GMT",
"version": "v2"
}
] | 2023-08-31 | [
[
"Oliver",
"Daniel J",
""
],
[
"Johnson",
"Aaron D",
""
],
[
"Berrier",
"Joel",
""
],
[
"Glampedakis",
"Kostas",
""
],
[
"Kennefick",
"Daniel",
""
]
] | Scattering events around a supermassive black hole will occasionally toss a stellar-mass compact object into an orbit around the supermassive black hole, beginning an extreme mass ratio inspiral. The early stages of such a highly eccentric orbit will not produce detectable gravitational waves as the source will only be in a suitable frequency band briefly when it is close to periapsis during each long-period orbit. This burst of emission, firmly in the millihertz band is the gravitational wave peep. While a single peep is not likely to be detectable, if we consider an ensemble of such subthreshold sources, spread across the universe, together they produce an unresolvable background noise that may obscure sources otherwise detectable by the Laser Interferometer Space Antenna, the proposed space-based gravitational wave detector. Previous studies of the extreme mass ratio burst signal confusion background focused more on parabolic orbits going very near the supermassive black hole and on events near the galactic center. We seek to improve this characterization by implementing numerical kludge waveforms that can calculate highly eccentric orbits with relativistic effects focusing on orbits which are farther away from the supermassive black hole and thus less likely to be detectable on their own, but will otherwise contribute to the background signal confusion noise. Here we present the waveforms and spectra of the gravitational wave peeps generated from recent calculations of extreme mass ratio inspirals/bursts capture parameters and discuss how these can be used to estimate the signal confusion noise generated by such events. |
gr-qc/9803057 | Kristen Menou | Kristen Menou, Eliot Quataert, Ramesh Narayan (Harvard-Smithsonian
Center for Astrophysics) | Astrophysical Evidence for Black Hole Event Horizons | LateX, 23 pages, 7 figures, uses crckapb.sty. To appear in the
Proceedings of the GR15 meeting, eds. N K Dadhich & J V Narlikar | null | null | EFI-94-11 | gr-qc | null | Astronomers have discovered many potential black holes in X-ray binaries and
galactic nuclei. These black holes are usually identified by the fact that they
are too massive to be neutron stars. Until recently, however, there was no
convincing evidence that the objects identified as black hole candidates
actually have event horizons. This has changed with extensive applications of a
class of accretion models for describing the flow of gas onto compact objects;
for these solutions, called advection-dominated accretion flows (ADAFs), the
black hole nature of the accreting star, specifically its event horizon, plays
an important role. We review the evidence that, at low luminosities, accreting
black holes in both X-ray binaries and galactic nuclei contain ADAFs rather
than the standard thin accretion disk.
| [
{
"created": "Mon, 16 Mar 1998 16:27:27 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Menou",
"Kristen",
"",
"Harvard-Smithsonian\n Center for Astrophysics"
],
[
"Quataert",
"Eliot",
"",
"Harvard-Smithsonian\n Center for Astrophysics"
],
[
"Narayan",
"Ramesh",
"",
"Harvard-Smithsonian\n Center for Astrophysics"
]
] | Astronomers have discovered many potential black holes in X-ray binaries and galactic nuclei. These black holes are usually identified by the fact that they are too massive to be neutron stars. Until recently, however, there was no convincing evidence that the objects identified as black hole candidates actually have event horizons. This has changed with extensive applications of a class of accretion models for describing the flow of gas onto compact objects; for these solutions, called advection-dominated accretion flows (ADAFs), the black hole nature of the accreting star, specifically its event horizon, plays an important role. We review the evidence that, at low luminosities, accreting black holes in both X-ray binaries and galactic nuclei contain ADAFs rather than the standard thin accretion disk. |
1905.12129 | Milko Estrada | Milko Estrada | A way of decoupling gravitational sources in pure Lovelock gravity | Accepted for publication in Eur.Phys.J.C | Eur. Phys. J. C (2019) 79: 918 | 10.1140/epjc/s10052-019-7444-6 | null | gr-qc | http://creativecommons.org/licenses/by-sa/4.0/ | We provide an algorithm that shows how to decouple gravitational sources in
Pure Lovelock gravity. This method allows to obtain several new and known
analytic solutions of physical interest in scenarios with extra dimensions and
with presence of higher curvature terms. Furthermore, using our method, it is
shown that applying the minimal geometric deformation to the Anti de Sitter
space time it is possible to obtain regular black hole solutions.
| [
{
"created": "Tue, 28 May 2019 23:13:04 GMT",
"version": "v1"
},
{
"created": "Fri, 31 May 2019 01:19:25 GMT",
"version": "v2"
},
{
"created": "Wed, 24 Jul 2019 17:58:24 GMT",
"version": "v3"
},
{
"created": "Wed, 30 Oct 2019 14:26:18 GMT",
"version": "v4"
}
] | 2019-11-13 | [
[
"Estrada",
"Milko",
""
]
] | We provide an algorithm that shows how to decouple gravitational sources in Pure Lovelock gravity. This method allows to obtain several new and known analytic solutions of physical interest in scenarios with extra dimensions and with presence of higher curvature terms. Furthermore, using our method, it is shown that applying the minimal geometric deformation to the Anti de Sitter space time it is possible to obtain regular black hole solutions. |
gr-qc/0112034 | Sanjay M. Wagh | S. M. Wagh, R. V. Saraykar, P. S. Muktibodh and K. S. Govinder | Spherical Gravitational Collapse with Heat Flux and Cosmic Censorship | Submitted to General Relativity and Gravitation | null | null | null | gr-qc | null | In this paper, we investigate the nature of the singularity in the
spherically symmetrical, shear-free, gravitational collapse of a star with heat
flux using a separable metric [cqg1]. For any non-singular, regular, radial
density profile for a star described by this metric, eq. (2.1), the singularity
of the gravitational collapse is not naked locally. Our results here
unequivocally support the Strong Cosmic Censorship Hypothesis.
| [
{
"created": "Sun, 16 Dec 2001 03:47:18 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Wagh",
"S. M.",
""
],
[
"Saraykar",
"R. V.",
""
],
[
"Muktibodh",
"P. S.",
""
],
[
"Govinder",
"K. S.",
""
]
] | In this paper, we investigate the nature of the singularity in the spherically symmetrical, shear-free, gravitational collapse of a star with heat flux using a separable metric [cqg1]. For any non-singular, regular, radial density profile for a star described by this metric, eq. (2.1), the singularity of the gravitational collapse is not naked locally. Our results here unequivocally support the Strong Cosmic Censorship Hypothesis. |
1201.4598 | Abhay Ashtekar | Abhay Ashtekar | Introduction to Loop Quantum Gravity | 30 pages, 2 figures. arXiv admin note: substantial text overlap with
arXiv:gr-qc/0410054 | null | 10.1007/978-3-642-33036-0_2 | IGC/12/1-5 | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This article is based on the opening lecture at the third quantum geometry
and quantum gravity school sponsored by the European Science Foundation and
held at Zakopane, Poland in March 2011. The goal of the lecture was to present
a broad perspective on loop quantum gravity for young researchers. The first
part is addressed to beginning students and the second to young researchers who
are already working in quantum gravity.
| [
{
"created": "Sun, 22 Jan 2012 20:46:13 GMT",
"version": "v1"
}
] | 2015-06-03 | [
[
"Ashtekar",
"Abhay",
""
]
] | This article is based on the opening lecture at the third quantum geometry and quantum gravity school sponsored by the European Science Foundation and held at Zakopane, Poland in March 2011. The goal of the lecture was to present a broad perspective on loop quantum gravity for young researchers. The first part is addressed to beginning students and the second to young researchers who are already working in quantum gravity. |
2009.01999 | Marcus Khuri | Marcus Khuri, Gilbert Weinstein, Sumio Yamada | 5-Dimensional Space-Periodic Solutions of the Static Vacuum Einstein
Equations | 16 pages | J. High Energy Phys. (2020), no. 12, Art. 2 | 10.1007/JHEP12(2020)002 | null | gr-qc hep-th math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An affirmative answer is given to a conjecture of Myers concerning the
existence of 5-dimensional regular static vacuum solutions that balance an
infinite number of black holes, which have Kasner asymptotics. A variety of
examples are constructed, having different combinations of ring $S^1\times S^2$
and sphere $S^3$ cross-sectional horizon topologies. Furthermore, we show the
existence of 5-dimensional vacuum solitons with Kasner asymptotics. These are
regular static space-periodic vacuum spacetimes devoid of black holes.
Consequently, we also obtain new examples of complete Riemannian manifolds of
nonnegative Ricci curvature in dimension 4, and zero Ricci curvature in
dimension 5, having arbitrarily large as well as infinite second Betti number.
| [
{
"created": "Fri, 4 Sep 2020 03:58:52 GMT",
"version": "v1"
},
{
"created": "Sun, 30 Jan 2022 19:23:51 GMT",
"version": "v2"
}
] | 2022-02-01 | [
[
"Khuri",
"Marcus",
""
],
[
"Weinstein",
"Gilbert",
""
],
[
"Yamada",
"Sumio",
""
]
] | An affirmative answer is given to a conjecture of Myers concerning the existence of 5-dimensional regular static vacuum solutions that balance an infinite number of black holes, which have Kasner asymptotics. A variety of examples are constructed, having different combinations of ring $S^1\times S^2$ and sphere $S^3$ cross-sectional horizon topologies. Furthermore, we show the existence of 5-dimensional vacuum solitons with Kasner asymptotics. These are regular static space-periodic vacuum spacetimes devoid of black holes. Consequently, we also obtain new examples of complete Riemannian manifolds of nonnegative Ricci curvature in dimension 4, and zero Ricci curvature in dimension 5, having arbitrarily large as well as infinite second Betti number. |
gr-qc/0004073 | Gennadii Varzugin | G. G. Varzugin | Equilibrium Configuration of Black Holes and the Inverse Scattering
Method | LaTeX, 14 pages, no figures | Theor.Math.Phys.111:667,1997; Teor.Mat.Fiz.111:345-355,1997 | 10.1007/BF02634055 | null | gr-qc | null | The inverse scattering method is applied to the investigation of the
equilibrium configuration of black holes. A study of the boundary problem
corresponding to this configuration shows that any axially symmetric,
stationary solution of the Einstein equations with disconnected event horizon
must belong to the class of Belinskii-Zakharov solutions. Relationships between
the angular momenta and angular velocities of black holes are derived.
| [
{
"created": "Mon, 24 Apr 2000 21:58:21 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Varzugin",
"G. G.",
""
]
] | The inverse scattering method is applied to the investigation of the equilibrium configuration of black holes. A study of the boundary problem corresponding to this configuration shows that any axially symmetric, stationary solution of the Einstein equations with disconnected event horizon must belong to the class of Belinskii-Zakharov solutions. Relationships between the angular momenta and angular velocities of black holes are derived. |
0708.1595 | Laurent Freidel | Laurent Freidel and Kirill Krasnov | A New Spin Foam Model for 4d Gravity | 40 pages; (v2) published version | Class.Quant.Grav.25:125018,2008 | 10.1088/0264-9381/25/12/125018 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Starting from Plebanski formulation of gravity as a constrained BF theory we
propose a new spin foam model for 4d Riemannian quantum gravity that
generalises the well-known Barrett-Crane model and resolves the inherent to it
ultra-locality problem. The BF formulation of 4d gravity possesses two sectors:
gravitational and topological ones. The model presented here is shown to give a
quantization of the gravitational sector, and is dual to the recently proposed
spin foam model of Engle et al. which, we show, corresponds to the topological
sector. Our methods allow us to introduce the Immirzi parameter into the
framework of spin foam quantisation. We generalize some of our considerations
to the Lorentzian setting and obtain a new spin foam model in that context as
well.
| [
{
"created": "Mon, 13 Aug 2007 14:05:22 GMT",
"version": "v1"
},
{
"created": "Sat, 7 Jun 2008 11:25:43 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Freidel",
"Laurent",
""
],
[
"Krasnov",
"Kirill",
""
]
] | Starting from Plebanski formulation of gravity as a constrained BF theory we propose a new spin foam model for 4d Riemannian quantum gravity that generalises the well-known Barrett-Crane model and resolves the inherent to it ultra-locality problem. The BF formulation of 4d gravity possesses two sectors: gravitational and topological ones. The model presented here is shown to give a quantization of the gravitational sector, and is dual to the recently proposed spin foam model of Engle et al. which, we show, corresponds to the topological sector. Our methods allow us to introduce the Immirzi parameter into the framework of spin foam quantisation. We generalize some of our considerations to the Lorentzian setting and obtain a new spin foam model in that context as well. |
gr-qc/0402049 | Johan Noldus | Luca Bombelli, Johan Noldus | The moduli space of isometry classes of globally hyperbolic spacetimes | 29 pages, 9 figures, submitted to Class. Quant. Grav | Class.Quant.Grav. 21 (2004) 4429-4454 | 10.1088/0264-9381/21/18/010 | null | gr-qc | null | This is the last article in a series of three initiated by the second author.
We elaborate on the concepts and theorems constructed in the previous articles.
In particular, we prove that the GH and the GGH uniformities previously
introduced on the moduli space of isometry classes of globally hyperbolic
spacetimes are different, but the Cauchy sequences which give rise to
well-defined limit spaces coincide. We then examine properties of the strong
metric introduced earlier on each spacetime, and answer some questions
concerning causality of limit spaces. Progress is made towards a general
definition of causality, and it is proven that the GGH limit of a Cauchy
sequence of $\mathcal{C}^{\pm}_{\alpha}$, path metric Lorentz spaces is again a
$\mathcal{C}^{\pm}_{\alpha}$, path metric Lorentz space. Finally, we give a
necessary and sufficient condition, similar to the one of Gromov for the
Riemannian case, for a class of Lorentz spaces to be precompact.
| [
{
"created": "Wed, 11 Feb 2004 10:06:40 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Bombelli",
"Luca",
""
],
[
"Noldus",
"Johan",
""
]
] | This is the last article in a series of three initiated by the second author. We elaborate on the concepts and theorems constructed in the previous articles. In particular, we prove that the GH and the GGH uniformities previously introduced on the moduli space of isometry classes of globally hyperbolic spacetimes are different, but the Cauchy sequences which give rise to well-defined limit spaces coincide. We then examine properties of the strong metric introduced earlier on each spacetime, and answer some questions concerning causality of limit spaces. Progress is made towards a general definition of causality, and it is proven that the GGH limit of a Cauchy sequence of $\mathcal{C}^{\pm}_{\alpha}$, path metric Lorentz spaces is again a $\mathcal{C}^{\pm}_{\alpha}$, path metric Lorentz space. Finally, we give a necessary and sufficient condition, similar to the one of Gromov for the Riemannian case, for a class of Lorentz spaces to be precompact. |
2003.08908 | Christof Wetterich | C. Wetterich | Primordial flat frame -- a new view on inflation | additional discussion of inhomogeneous cosmological solutions and big
bang singularity , 31 pages | null | 10.1103/PhysRevD.104.083525 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Models of inflationary cosmology admit a choice of the metric for which the
geometry of homogeneous isotropic solutions becomes flat Minkowski space in the
infinite past. In this primordial flat frame all mass scales vanish in the
infinite past and quantum scale symmetry is realized. The cosmological
evolution is dominantly described by the slow increase of a scalar field which
sets the scale of all masses. We construct the primordial flat frame for
standard models of inflation as Starobinsky inflation or chaotic inflation. In
particular, we discuss the evolution of inhomogeneous solutions in the
neighborhood of the homogeneous isotropic background solution and their
relation to the observable primordial fluctuation spectrum. If the propagators
for the graviton and scalar field remain regular, our observed inhomogeneous
Universe can be extrapolated back to the infinite past in physical time. In
this case there is no physical big-bang singularity -- the latter reflects only
a singular choice of ``field coordinates". Independently of the issue of
singularity the primordial flat frame offers a new view on the physical
properties of the inflationary universe, which can be characterized as a very
slowly evolving almost empty vacuum state with approximate scale symmetry.
| [
{
"created": "Thu, 19 Mar 2020 17:15:41 GMT",
"version": "v1"
},
{
"created": "Wed, 1 Jul 2020 12:24:28 GMT",
"version": "v2"
},
{
"created": "Mon, 18 Jan 2021 13:49:38 GMT",
"version": "v3"
},
{
"created": "Sun, 19 Sep 2021 17:17:32 GMT",
"version": "v4"
}
] | 2021-10-27 | [
[
"Wetterich",
"C.",
""
]
] | Models of inflationary cosmology admit a choice of the metric for which the geometry of homogeneous isotropic solutions becomes flat Minkowski space in the infinite past. In this primordial flat frame all mass scales vanish in the infinite past and quantum scale symmetry is realized. The cosmological evolution is dominantly described by the slow increase of a scalar field which sets the scale of all masses. We construct the primordial flat frame for standard models of inflation as Starobinsky inflation or chaotic inflation. In particular, we discuss the evolution of inhomogeneous solutions in the neighborhood of the homogeneous isotropic background solution and their relation to the observable primordial fluctuation spectrum. If the propagators for the graviton and scalar field remain regular, our observed inhomogeneous Universe can be extrapolated back to the infinite past in physical time. In this case there is no physical big-bang singularity -- the latter reflects only a singular choice of ``field coordinates". Independently of the issue of singularity the primordial flat frame offers a new view on the physical properties of the inflationary universe, which can be characterized as a very slowly evolving almost empty vacuum state with approximate scale symmetry. |
gr-qc/9303020 | Don N. Page | Don N. Page | Clock Time and Entropy | 14 pages, plain TeX, report Alberta-Thy-12-93, To be published in
{\it Physical Origins of Time Asymmetry,} Eds. J. J. Halliwell, J.
Perez-Mercader, and W. H. \.Zurek, Cambridge University Press, Cambridge
(1993) | null | null | null | gr-qc | null | Testable conditional probabilities appear to be restricted to single
hypersurfaces (marvelous moments) and depend only on stationary observables.
Observable evolution, such as a change of entropy, should be expressed as a
dependence upon clock time, not upon inaccessible coordinate time.
| [
{
"created": "Fri, 12 Mar 1993 22:09:05 GMT",
"version": "v1"
},
{
"created": "Fri, 12 Mar 1993 22:33:24 GMT",
"version": "v2"
}
] | 2008-02-03 | [
[
"Page",
"Don N.",
""
]
] | Testable conditional probabilities appear to be restricted to single hypersurfaces (marvelous moments) and depend only on stationary observables. Observable evolution, such as a change of entropy, should be expressed as a dependence upon clock time, not upon inaccessible coordinate time. |
1305.4193 | Yasusada Nambu | Yasusada Nambu | Entanglement Structure in Expanding Universes | 29 pages. arXiv admin note: text overlap with arXiv:1105.5212 | Entropy 2013, 15(3) 1847-1874 | 10.3390/e15051847 | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate entanglement of a quantum field in de Sitter spacetime using a
particle detector model. By considering the entanglement between two comoving
detectors interacting with a scalar field, it is possible to detect the
entanglement of the scalar field by swapping it to detectors. For the massless
minimal scalar field, we find that the entanglement between the detectors
cannot be detected when their physical separation exceeds the Hubble horizon
scale. This behavior supports the appearance of the classical nature of quantum
fluctuations generated during the inflationary era.
| [
{
"created": "Fri, 17 May 2013 21:15:02 GMT",
"version": "v1"
}
] | 2015-06-16 | [
[
"Nambu",
"Yasusada",
""
]
] | We investigate entanglement of a quantum field in de Sitter spacetime using a particle detector model. By considering the entanglement between two comoving detectors interacting with a scalar field, it is possible to detect the entanglement of the scalar field by swapping it to detectors. For the massless minimal scalar field, we find that the entanglement between the detectors cannot be detected when their physical separation exceeds the Hubble horizon scale. This behavior supports the appearance of the classical nature of quantum fluctuations generated during the inflationary era. |
gr-qc/0506010 | Anzhong Wang | Anzhong Wang and Yumei Wu | Kink Stability of Self-Similar Solutions of Scalar Field in 2+1 Gravity | latex, one figure | Gen.Rel.Grav.39:663-676,2007; Gen.Rel.Grav.39:677-684,2007 | 10.1007/s10714-007-0413-7 | null | gr-qc | null | The kink stability of self-similar solutions of a massless scalar field with
circular symmetry in 2+1 gravity is studied, and found that such solutions are
unstable against the kink perturbations along the sonic line (self-similar
horizon). However, when perturbations outside the sonic line are considered,
and taking the ones along the sonic line as their boundary conditions, we find
that non-trivial perturbations do not exist. In other words, the consideration
of perturbations outside the sonic line limits the unstable mode of the
perturbations found along the sonic line. As a result, the critical solution
for the scalar collapse remains critical even after the kink perturbations are
taken into account.
| [
{
"created": "Wed, 1 Jun 2005 20:05:18 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Wang",
"Anzhong",
""
],
[
"Wu",
"Yumei",
""
]
] | The kink stability of self-similar solutions of a massless scalar field with circular symmetry in 2+1 gravity is studied, and found that such solutions are unstable against the kink perturbations along the sonic line (self-similar horizon). However, when perturbations outside the sonic line are considered, and taking the ones along the sonic line as their boundary conditions, we find that non-trivial perturbations do not exist. In other words, the consideration of perturbations outside the sonic line limits the unstable mode of the perturbations found along the sonic line. As a result, the critical solution for the scalar collapse remains critical even after the kink perturbations are taken into account. |
gr-qc/9409051 | Dr. Scott C. Smith | Scott C. Smith, Joan M. Centrella, and Sean P. Clancy | A Three-Dimensional Hydrodynamics Code for Modeling Sources of
Gravitational Radiation | 51 pages, LaTeX with AASTEX macros, 12 figures available - send fax
number or surface address to scott@eagle.drexel.edu. ApJ Supp. (in press) | ApJS 94 (1994) 789 | 10.1086/192090 | null | gr-qc astro-ph | null | We have developed a 3-D Eulerian hydrodynamics code to model sources of
gravitational radiation. The code is written in cylindrical coordinates
$(\varpi,z,\varphi)$ and has moving grids in the $\varpi$ and $z$-directions.
We use Newtonian gravity and calculate the gravitational radiation in the
quadrupole approximation. This code has been tested on a variety of problems to
verify its accuracy and stability, and the results of these tests are reported
here.
| [
{
"created": "Fri, 23 Sep 1994 16:51:45 GMT",
"version": "v1"
},
{
"created": "Mon, 26 Sep 1994 14:53:17 GMT",
"version": "v2"
}
] | 2009-10-22 | [
[
"Smith",
"Scott C.",
""
],
[
"Centrella",
"Joan M.",
""
],
[
"Clancy",
"Sean P.",
""
]
] | We have developed a 3-D Eulerian hydrodynamics code to model sources of gravitational radiation. The code is written in cylindrical coordinates $(\varpi,z,\varphi)$ and has moving grids in the $\varpi$ and $z$-directions. We use Newtonian gravity and calculate the gravitational radiation in the quadrupole approximation. This code has been tested on a variety of problems to verify its accuracy and stability, and the results of these tests are reported here. |
1207.1488 | Steven Carlip | S. Carlip | Effective Conformal Descriptions of Black Hole Entropy: A Review | To appear in Proc. of the Sixth International School on Field Theory
and Gravity, Petropolis, Brazil, 2012 | null | 10.1063/1.4756962 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Black holes behave as thermodynamic objects, and it is natural to ask for an
underlying "statistical mechanical" explanation in terms of microscopic degrees
of freedom. I summarize attempts to describe these degrees of freedom in terms
of a dual two-dimensional conformal field theory, emphasizing the generality of
the Cardy formula and the consequent universal nature of the conformal
description.
| [
{
"created": "Thu, 5 Jul 2012 23:54:20 GMT",
"version": "v1"
}
] | 2015-06-05 | [
[
"Carlip",
"S.",
""
]
] | Black holes behave as thermodynamic objects, and it is natural to ask for an underlying "statistical mechanical" explanation in terms of microscopic degrees of freedom. I summarize attempts to describe these degrees of freedom in terms of a dual two-dimensional conformal field theory, emphasizing the generality of the Cardy formula and the consequent universal nature of the conformal description. |
1806.05674 | Tan Liu | Tan Liu, Xing Zhang, Wen Zhao, Kai Lin, Chao Zhang, Shaojun Zhang,
Xiang Zhao, Tao Zhu and Anzhong Wang | Waveforms of compact binary inspiral gravitational radiation in screened
modified gravity | 21 pages, to appear in PRD | Phys. Rev. D 98, 083023 (2018) | 10.1103/PhysRevD.98.083023 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Scalar-tensor gravity, with the screening mechanisms to avoid the severe
constraints of the fifth force in the Solar System, can be described with a
unified theoretical framework, the so-called screened modified gravity (SMG).
Within this framework, in this paper we calculate the waveforms of
gravitational-waves (GWs) emitted by inspiral compact binaries, which include
four polarization modes, the plus $h_{+}$, cross $h_{\times}$, breathing
$h_{b}$, and longitudinal $h_{L}$ modes. The scalar polarizations $h_b$ and
$h_L$ are both caused by the scalar field of SMG, and satisfy a simple linear
relation. With the stationary phase approximations, we obtain their Fourier
transforms, and derive the correction terms in the amplitude, phase, and
polarizations of GWs, relative to the corresponding results in general
relativity. The corresponding parametrized post-Einsteinian parameters in the
general SMG are also identified. Imposing the noise level of the ground-based
Einstein Telescope, we find that GW detections from inspiral compact binaries
composed of a neutron star and a black hole can place stringent constraints on
the sensitivities of neutron stars, and the bound is applicable to any SMG
theory. Finally, we apply these results to some specific theories of SMG,
including chameleon, symmetron, dilaton and $f(R)$.
| [
{
"created": "Thu, 14 Jun 2018 03:40:03 GMT",
"version": "v1"
},
{
"created": "Thu, 11 Oct 2018 11:53:29 GMT",
"version": "v2"
}
] | 2018-10-31 | [
[
"Liu",
"Tan",
""
],
[
"Zhang",
"Xing",
""
],
[
"Zhao",
"Wen",
""
],
[
"Lin",
"Kai",
""
],
[
"Zhang",
"Chao",
""
],
[
"Zhang",
"Shaojun",
""
],
[
"Zhao",
"Xiang",
""
],
[
"Zhu",
"Tao",
""
]... | Scalar-tensor gravity, with the screening mechanisms to avoid the severe constraints of the fifth force in the Solar System, can be described with a unified theoretical framework, the so-called screened modified gravity (SMG). Within this framework, in this paper we calculate the waveforms of gravitational-waves (GWs) emitted by inspiral compact binaries, which include four polarization modes, the plus $h_{+}$, cross $h_{\times}$, breathing $h_{b}$, and longitudinal $h_{L}$ modes. The scalar polarizations $h_b$ and $h_L$ are both caused by the scalar field of SMG, and satisfy a simple linear relation. With the stationary phase approximations, we obtain their Fourier transforms, and derive the correction terms in the amplitude, phase, and polarizations of GWs, relative to the corresponding results in general relativity. The corresponding parametrized post-Einsteinian parameters in the general SMG are also identified. Imposing the noise level of the ground-based Einstein Telescope, we find that GW detections from inspiral compact binaries composed of a neutron star and a black hole can place stringent constraints on the sensitivities of neutron stars, and the bound is applicable to any SMG theory. Finally, we apply these results to some specific theories of SMG, including chameleon, symmetron, dilaton and $f(R)$. |
gr-qc/0611136 | Hideaki Kudoh | Hideaki Kudoh | Doubly Spinning Black Rings | 20 pages, 6 figures | Phys.Rev.D75:064006,2007 | 10.1103/PhysRevD.75.064006 | UTAP-571 | gr-qc hep-th | null | We study a method to solve stationary axisymmetric vacuum Einstein equations
numerically. As an illustration, the five-dimensional doubly spinning black
rings that have two independent angular momenta are formulated in a way
suitable for fully nonlinear numerical method. Expanding for small second
angular velocity, the formulation is solved perturbatively upto second order
involving the backreaction from the second spin. The obtained solutions are
regular without conical singularity, and the physical properties are discussed
with the phase diagram of the reduced entropy vs the reduced angular momenta.
Possible extensions of the present approach to constructing the higher
dimensional version of black ring and the ring with the cosmological constant
are also discussed.
| [
{
"created": "Mon, 27 Nov 2006 12:19:55 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Kudoh",
"Hideaki",
""
]
] | We study a method to solve stationary axisymmetric vacuum Einstein equations numerically. As an illustration, the five-dimensional doubly spinning black rings that have two independent angular momenta are formulated in a way suitable for fully nonlinear numerical method. Expanding for small second angular velocity, the formulation is solved perturbatively upto second order involving the backreaction from the second spin. The obtained solutions are regular without conical singularity, and the physical properties are discussed with the phase diagram of the reduced entropy vs the reduced angular momenta. Possible extensions of the present approach to constructing the higher dimensional version of black ring and the ring with the cosmological constant are also discussed. |
2012.13429 | Muhammad Zahid Mughal | Muhammad Zahid Mughal, Iftikhar Ahmad | A multifield tachyon quintom model of dark energy and fate of the
universe | 10 pages, 3 figures, 10 sub figures, 2 tables | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We investigate a multi-field model of dark energy in this paper. We develop a
model of dark energy with two multiple scalar fields, one we consider, is a
multifield tachyon and the other is multi-field phantom tachyon scalars. We
make an analysis of the system in phase space by considering inverse square
potentials suitable for these models. Through the development of an autonomous
dynamical system, the critical points and their stability analysis is
performed. It has been observed that these stable critical points are satisfied
by power law solutions. Moving on towards the analysis we can predict the fate
of the universe. A special feature of this model is that it affects the
equation of state parameter w to alter from being it greater than negative one
to be less than it during the evolutionary phase of the universe. Thus, its all
about the phantom divide which turns out to be decisive in the evolution of the
cosmos in these models.
| [
{
"created": "Thu, 24 Dec 2020 19:24:25 GMT",
"version": "v1"
}
] | 2020-12-29 | [
[
"Mughal",
"Muhammad Zahid",
""
],
[
"Ahmad",
"Iftikhar",
""
]
] | We investigate a multi-field model of dark energy in this paper. We develop a model of dark energy with two multiple scalar fields, one we consider, is a multifield tachyon and the other is multi-field phantom tachyon scalars. We make an analysis of the system in phase space by considering inverse square potentials suitable for these models. Through the development of an autonomous dynamical system, the critical points and their stability analysis is performed. It has been observed that these stable critical points are satisfied by power law solutions. Moving on towards the analysis we can predict the fate of the universe. A special feature of this model is that it affects the equation of state parameter w to alter from being it greater than negative one to be less than it during the evolutionary phase of the universe. Thus, its all about the phantom divide which turns out to be decisive in the evolution of the cosmos in these models. |
1704.03040 | Farhad Darabi | F. Darabi, K. Atazadeh | Einstein static universe, GUP, and natural IR and UV cut-offs | 10 pages, Minor revision, Title change; To be published in "Int. J.
Geom. Methods Mod. Phys" | Int. J. Geometric Methods in Modern Physics 15, 5 (2018) 1850083 | 10.1142/S0219887818500834 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the Einstein static universe in the framework of Generalized
Uncertainty Principle constructed by the Snyder non-commutative space. It is
shown that the deformation parameter can induce an effective energy density
subject to GUP which obeys the holographic principle (HP) and plays the role of
a cosmological constant. Using the holographic feature of this effective energy
density, we introduce natural IR and UV cut-offs which depend on the GUP based
effective equation of state. Moreover, we propose a solution to the
cosmological constant problem. This solution is based on the result that the
Einstein equations just couple to the tiny holographic based surface energy
density (cosmological constant) induced by the deformation parameter, rather
than the large quantum gravitational based volume energy density (vacuum
energy) having contributions of order $M_P^4$.
| [
{
"created": "Mon, 10 Apr 2017 20:12:59 GMT",
"version": "v1"
},
{
"created": "Fri, 16 Feb 2018 15:02:04 GMT",
"version": "v2"
}
] | 2019-05-01 | [
[
"Darabi",
"F.",
""
],
[
"Atazadeh",
"K.",
""
]
] | We study the Einstein static universe in the framework of Generalized Uncertainty Principle constructed by the Snyder non-commutative space. It is shown that the deformation parameter can induce an effective energy density subject to GUP which obeys the holographic principle (HP) and plays the role of a cosmological constant. Using the holographic feature of this effective energy density, we introduce natural IR and UV cut-offs which depend on the GUP based effective equation of state. Moreover, we propose a solution to the cosmological constant problem. This solution is based on the result that the Einstein equations just couple to the tiny holographic based surface energy density (cosmological constant) induced by the deformation parameter, rather than the large quantum gravitational based volume energy density (vacuum energy) having contributions of order $M_P^4$. |
1503.04354 | Rainer Collier | Rainer Collier | Ideal Quantum Gases with Planck Scale Limitations | 48 pages, 13 figures | null | null | null | gr-qc cond-mat.quant-gas quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A thermodynamic system of non-interacting quantum particles changes its
statistical distribution formulas if there is a universal limitation for the
size of energetic quantum leaps (magnitude of quantum leaps smaller than Planck
energy). By means of a restriction of the a priori equiprobability postulate
one can reach a thermodynamic foundation of these corrected distribution
formulas. The number of microstates is determined by means of a suitable
counting method and combined with thermodynamics via the Boltzmann principle.
The result is that, for particle energies that come close to the Planck energy,
the thermodynamic difference between fermion and boson distribution vanishes.
Both distributions then approximate a Boltzmann distribution. The wave and
particle character of the quantum particles, too, can be influenced by choosing
the size of the temperature and particle energy parameters relative to the
Planck energy, as you can see from the associated fluctuation formulas. In the
case of non-relativistic degeneration, the critical parameters Fermi momentum
(fermions) and Einstein temperature (bosons) vanish as soon as the rest energy
of the quantum particles reaches the Planck energy. For the Bose-Einstein
condensation there exists, in the condensation range, a finite upper limit for
the number of particles in the ground state, which is determined by the ratio
of Planck mass to the rest mass of the quantum particles. In the relativistic
high-temperature range, the energy densities of photon and neutrino radiation
have finite limit values, which is of interest with regard to the start of
cosmic expansion.
| [
{
"created": "Sat, 14 Mar 2015 22:00:25 GMT",
"version": "v1"
}
] | 2015-03-17 | [
[
"Collier",
"Rainer",
""
]
] | A thermodynamic system of non-interacting quantum particles changes its statistical distribution formulas if there is a universal limitation for the size of energetic quantum leaps (magnitude of quantum leaps smaller than Planck energy). By means of a restriction of the a priori equiprobability postulate one can reach a thermodynamic foundation of these corrected distribution formulas. The number of microstates is determined by means of a suitable counting method and combined with thermodynamics via the Boltzmann principle. The result is that, for particle energies that come close to the Planck energy, the thermodynamic difference between fermion and boson distribution vanishes. Both distributions then approximate a Boltzmann distribution. The wave and particle character of the quantum particles, too, can be influenced by choosing the size of the temperature and particle energy parameters relative to the Planck energy, as you can see from the associated fluctuation formulas. In the case of non-relativistic degeneration, the critical parameters Fermi momentum (fermions) and Einstein temperature (bosons) vanish as soon as the rest energy of the quantum particles reaches the Planck energy. For the Bose-Einstein condensation there exists, in the condensation range, a finite upper limit for the number of particles in the ground state, which is determined by the ratio of Planck mass to the rest mass of the quantum particles. In the relativistic high-temperature range, the energy densities of photon and neutrino radiation have finite limit values, which is of interest with regard to the start of cosmic expansion. |
1306.4979 | Galina L. Klimchitskaya | G. L. Klimchitskaya, U. Mohideen, and V. M. Mostepanenko | Constraints on corrections to Newtonian gravity from two recent
measurements of the Casimir interaction between metallic surfaces | 18 pages, 5 figures; to appear in Phys. Rev. D | Phys. Rev. D, v.87, 125031 (2013) | 10.1103/PhysRevD.87.125031 | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We obtain constraints on parameters of the Yukawa-type corrections to
Newton's gravitational law from measurements of the gradient of the Casimir
force between surfaces coated with ferromagnetic metal Ni and from measurements
of the Casimir force between Au-coated sinusoidally corrugated surfaces at
various angles between corrugations. It is shown that constraints following
from the experiment with magnetic surfaces are slightly weaker than currently
available strongest constraints, but benefit from increased reliability and
independence of systematic effects.The constraints derived from the experiment
with corrugated surfaces within the interaction region from 11.6 to 29.2\,nm
are stronger up to a factor of 4 than the strongest constraints derived from
other experiments. The possibility of further strengthening of constraints on
non-Newtonian gravity by using the configurations with corrugated boundaries is
proposed.
| [
{
"created": "Thu, 20 Jun 2013 11:17:33 GMT",
"version": "v1"
}
] | 2013-07-17 | [
[
"Klimchitskaya",
"G. L.",
""
],
[
"Mohideen",
"U.",
""
],
[
"Mostepanenko",
"V. M.",
""
]
] | We obtain constraints on parameters of the Yukawa-type corrections to Newton's gravitational law from measurements of the gradient of the Casimir force between surfaces coated with ferromagnetic metal Ni and from measurements of the Casimir force between Au-coated sinusoidally corrugated surfaces at various angles between corrugations. It is shown that constraints following from the experiment with magnetic surfaces are slightly weaker than currently available strongest constraints, but benefit from increased reliability and independence of systematic effects.The constraints derived from the experiment with corrugated surfaces within the interaction region from 11.6 to 29.2\,nm are stronger up to a factor of 4 than the strongest constraints derived from other experiments. The possibility of further strengthening of constraints on non-Newtonian gravity by using the configurations with corrugated boundaries is proposed. |
gr-qc/0405089 | Sigbjorn Hervik | Alan A. Coley and Sigbjorn Hervik | Brane Waves | 9 pages v3:revised version, to appear in CQG | Class.Quant.Grav. 21 (2004) 5759-5766 | 10.1088/0264-9381/21/24/005 | null | gr-qc astro-ph hep-th | null | In brane-world cosmology gravitational waves can propagate in the higher
dimensions (i.e., in the `bulk'). In some appropriate regimes the bulk
gravitational waves may be approximated by plane waves. We systematically study
five-dimensional gravitational waves that are algebraically special and of type
N. In the most physically relevant case the projected non-local stress tensor
on the brane is formally equivalent to the energy-momentum tensor of a null
fluid. Some exact solutions are studied to illustrate the features of these
branes; in particular, we show explicity that any plane wave brane can be
embedded into a 5-dimensional Siklos spacetime. More importantly, it is
possible that in some appropriate regime the bulk can be approximated by
gravitational plane waves and thus may act as initial conditions for the
gravitational field in the bulk (thereby enabling the field equations to be
integrated on the brane).
| [
{
"created": "Mon, 17 May 2004 16:57:24 GMT",
"version": "v1"
},
{
"created": "Sun, 23 May 2004 16:00:47 GMT",
"version": "v2"
},
{
"created": "Thu, 21 Oct 2004 19:08:19 GMT",
"version": "v3"
}
] | 2009-11-10 | [
[
"Coley",
"Alan A.",
""
],
[
"Hervik",
"Sigbjorn",
""
]
] | In brane-world cosmology gravitational waves can propagate in the higher dimensions (i.e., in the `bulk'). In some appropriate regimes the bulk gravitational waves may be approximated by plane waves. We systematically study five-dimensional gravitational waves that are algebraically special and of type N. In the most physically relevant case the projected non-local stress tensor on the brane is formally equivalent to the energy-momentum tensor of a null fluid. Some exact solutions are studied to illustrate the features of these branes; in particular, we show explicity that any plane wave brane can be embedded into a 5-dimensional Siklos spacetime. More importantly, it is possible that in some appropriate regime the bulk can be approximated by gravitational plane waves and thus may act as initial conditions for the gravitational field in the bulk (thereby enabling the field equations to be integrated on the brane). |
2104.03766 | Yotam Sherf | Yotam Sherf | Tidal-heating/viscous dissipation correspondence in black holes and
viscous compact objects | Replaced to agree with the published version. Typo in Eq.10 was
corrected | null | 10.1103/PhysRevD.103.104003 | null | gr-qc astro-ph.HE hep-ph hep-th | http://creativecommons.org/publicdomain/zero/1.0/ | The effect of energy absorption during the binary evolution of
Exotic-compact-objects (ECOs) is extensively studied. We review the underlying
mechanism that provides the energy dissipation in material objects - tidal
friction. We show that unlike typical astrophysical objects, where absorption
due to viscosity is negligible, in ECOs, absorption could potentially mimic the
analogous effect of black-holes (BHs) - tidal heating. We stand for their
differences and similarities in the context of energy dissipation during the
inspiral. Inspired by the membrane paradigm and recent studies, we demonstrate
how viscosity is a defining feature that quantifies how close is the ECO
absorption to that of a classical BH absorption. We show that for ECOs,
viscosity can induce significant modifications to the GW waveform, which in
some favorable scenarios of super-massive binaries of equal mass and spin,
enables the measurement of the ECO absorption in the future precision
gravitational-wave (GW) observations. Finally, we discuss the implications on
the ECO reflection coefficient and the relation to the universal viscosity to
volume entropy bound.
| [
{
"created": "Thu, 8 Apr 2021 13:39:38 GMT",
"version": "v1"
},
{
"created": "Fri, 2 Jul 2021 13:17:34 GMT",
"version": "v2"
}
] | 2021-07-05 | [
[
"Sherf",
"Yotam",
""
]
] | The effect of energy absorption during the binary evolution of Exotic-compact-objects (ECOs) is extensively studied. We review the underlying mechanism that provides the energy dissipation in material objects - tidal friction. We show that unlike typical astrophysical objects, where absorption due to viscosity is negligible, in ECOs, absorption could potentially mimic the analogous effect of black-holes (BHs) - tidal heating. We stand for their differences and similarities in the context of energy dissipation during the inspiral. Inspired by the membrane paradigm and recent studies, we demonstrate how viscosity is a defining feature that quantifies how close is the ECO absorption to that of a classical BH absorption. We show that for ECOs, viscosity can induce significant modifications to the GW waveform, which in some favorable scenarios of super-massive binaries of equal mass and spin, enables the measurement of the ECO absorption in the future precision gravitational-wave (GW) observations. Finally, we discuss the implications on the ECO reflection coefficient and the relation to the universal viscosity to volume entropy bound. |
gr-qc/0701155 | Jun-Hong An | Shun-Jin Wang | On the super-fluid property of the relativistic physical vacuum medium
and the inertial motion of particles | 4 pages | null | null | null | gr-qc | null | The similarity between the energy spectra of relativistic particles and that
of quasi-particles in super-conductivity BCS theory makes us conjecture that
the relativistic physical vacuum medium as the ground state of the background
field is a super fluid medium, and the rest mass of a relativistic particle is
like the energy gap of a quasi-particle. This conjecture is strongly supported
by the results of our following investigation: a particle moving through the
vacuum medium at a speed less than the speed of light in vacuum, though
interacting with the vacuum medium, never feels friction force and thus
undergoes a frictionless and inertial motion. The profound and intrinsic
relationship between the super fluid property of the relativistic physical
vacuum medium and the energy-momentum conservation law as well as the
relativistic energy-momentum dispersion relation or the principle of
relativity, can be established.
| [
{
"created": "Mon, 29 Jan 2007 03:45:05 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Wang",
"Shun-Jin",
""
]
] | The similarity between the energy spectra of relativistic particles and that of quasi-particles in super-conductivity BCS theory makes us conjecture that the relativistic physical vacuum medium as the ground state of the background field is a super fluid medium, and the rest mass of a relativistic particle is like the energy gap of a quasi-particle. This conjecture is strongly supported by the results of our following investigation: a particle moving through the vacuum medium at a speed less than the speed of light in vacuum, though interacting with the vacuum medium, never feels friction force and thus undergoes a frictionless and inertial motion. The profound and intrinsic relationship between the super fluid property of the relativistic physical vacuum medium and the energy-momentum conservation law as well as the relativistic energy-momentum dispersion relation or the principle of relativity, can be established. |
2312.10754 | Jose Luis Bl\'azquez-Salcedo | Jose Luis Bl\'azquez-Salcedo, Fech Scen Khoo, Jutta Kunz, Luis Manuel
Gonz\'alez-Romero | Quasinormal modes of Kerr black holes using a spectral decomposition of
the metric perturbations | 18 pages, 5 figures. v2: Minor changes to match published version | Phys. Rev. D 109, 064028 (2024) | 10.1103/PhysRevD.109.064028 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We report a new method to calculate the quasinormal modes of rotating black
holes, using a spectral decomposition to solve the partial differential
equations that result from introducing linear metric perturbations to a
rotating background. Our approach allows us to calculate a large sector of the
quasinormal mode spectrum. In particular, we study the accuracy of the method
for the $(l=2)$-led and $(l=3)$-led modes for different values of the $M_z$
azimuthal number, considering the fundamental modes as well as the first two
excitations. We show that our method reproduces the Kerr fundamental modes with
an accuracy of $10^{-6}$ or better for $a/M<0.8$, while it stays below $0.1\%$
for $a/M<0.98$.
| [
{
"created": "Sun, 17 Dec 2023 16:04:02 GMT",
"version": "v1"
},
{
"created": "Fri, 15 Mar 2024 09:56:48 GMT",
"version": "v2"
}
] | 2024-03-18 | [
[
"Blázquez-Salcedo",
"Jose Luis",
""
],
[
"Khoo",
"Fech Scen",
""
],
[
"Kunz",
"Jutta",
""
],
[
"González-Romero",
"Luis Manuel",
""
]
] | We report a new method to calculate the quasinormal modes of rotating black holes, using a spectral decomposition to solve the partial differential equations that result from introducing linear metric perturbations to a rotating background. Our approach allows us to calculate a large sector of the quasinormal mode spectrum. In particular, we study the accuracy of the method for the $(l=2)$-led and $(l=3)$-led modes for different values of the $M_z$ azimuthal number, considering the fundamental modes as well as the first two excitations. We show that our method reproduces the Kerr fundamental modes with an accuracy of $10^{-6}$ or better for $a/M<0.8$, while it stays below $0.1\%$ for $a/M<0.98$. |
gr-qc/0411044 | Giovanni Montani | Giovanni Montani and Riccardo Benini | Frame-independence of the Inhomogeneous Mixmaster Chaos via
Misner-Chitre'-like variables | 8 pages,2 figures, to appear on Phys Rev D | Phys.Rev. D70 (2004) 103527 | 10.1103/PhysRevD.70.103527 | null | gr-qc | null | We outline the covariant nature,with respect to the choice of a reference
frame, of the chaos characterizing the generic cosmological solution near the
initial singularity, i.e. the so-called inhomogeneous Mixmaster model. Our
analysis is based on a "gauge" independent ADM-reduction of the dynamics to the
physical degrees of freedom. The out coming picture shows how the inhomogeneous
Mixmaster model is isomorphic point by point in space to a billiard on a
Lobachevsky plane. Indeed, the existence of an asymptotic (energy-like)
constant of the motion allows to construct the Jacobi metric associated to the
geodesic flow and to calculate a non-zero Lyapunov exponent in each space
point. The chaos covariance emerges from the independence of our scheme with
respect to the form of the lapse function and the shift vector; the origin of
this result relies on the dynamical decoupling of the space-points which takes
place near the singularity, due to the asymptotic approach of the potential
term to infinite walls. At the ground of the obtained dynamical scheme is the
choice of Misner-Chitre' like variables which allows to fix the billiard
potential walls.
| [
{
"created": "Tue, 9 Nov 2004 11:46:45 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Montani",
"Giovanni",
""
],
[
"Benini",
"Riccardo",
""
]
] | We outline the covariant nature,with respect to the choice of a reference frame, of the chaos characterizing the generic cosmological solution near the initial singularity, i.e. the so-called inhomogeneous Mixmaster model. Our analysis is based on a "gauge" independent ADM-reduction of the dynamics to the physical degrees of freedom. The out coming picture shows how the inhomogeneous Mixmaster model is isomorphic point by point in space to a billiard on a Lobachevsky plane. Indeed, the existence of an asymptotic (energy-like) constant of the motion allows to construct the Jacobi metric associated to the geodesic flow and to calculate a non-zero Lyapunov exponent in each space point. The chaos covariance emerges from the independence of our scheme with respect to the form of the lapse function and the shift vector; the origin of this result relies on the dynamical decoupling of the space-points which takes place near the singularity, due to the asymptotic approach of the potential term to infinite walls. At the ground of the obtained dynamical scheme is the choice of Misner-Chitre' like variables which allows to fix the billiard potential walls. |
gr-qc/9811071 | V. Suneeta | V.Suneeta, R.K.Kaul and T.R.Govindarajan | BTZ Black Hole Entropy from Ponzano-Regge Gravity | 11 pages LaTeX, 3 eps figures, some minor clarifications added,
result unchanged | Mod.Phys.Lett. A14 (1999) 349-358 | 10.1142/S0217732399000407 | IMSc-98/11/52, SU 4240-689 | gr-qc hep-th | null | The entropy of the BTZ black hole is computed in the Ponzano-Regge
formulation of three-dimensional lattice gravity. It is seen that the correct
semi-classical behaviour of entropy is reproduced by states that correspond to
all possible triangulations of the Euclidean black hole.
| [
{
"created": "Fri, 20 Nov 1998 05:53:21 GMT",
"version": "v1"
},
{
"created": "Mon, 11 Jan 1999 10:01:43 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Suneeta",
"V.",
""
],
[
"Kaul",
"R. K.",
""
],
[
"Govindarajan",
"T. R.",
""
]
] | The entropy of the BTZ black hole is computed in the Ponzano-Regge formulation of three-dimensional lattice gravity. It is seen that the correct semi-classical behaviour of entropy is reproduced by states that correspond to all possible triangulations of the Euclidean black hole. |
1301.7074 | Luis Lehner | Carlos Palenzuela, Luis Lehner, Marcelo Ponce, Steven L. Liebling,
Matthew Anderson, David Neilsen, Patrick Motl | Gravitational and electromagnetic outputs from binary neutron star
mergers | 6 pages, 3 figures. Updated version to appear in Phys.Rev.Letters | PhysRevLett 111.061105 (2013) | 10.1103/PhysRevLett.111.061105 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The late stage of an inspiraling neutron star binary gives rise to strong
gravitational wave emission due to its highly dynamic, strong gravity.
Moreover, interactions between the stellar magnetospheres can produce
considerable electromagnetic radiation. We study this scenario using fully
general relativistic, resistive magneto-hydrodynamics simulations. We show that
these interactions extract kinetic energy from the system, dissipate heat, and
power radiative Poynting flux, as well as develop current sheets. Our results
indicate that this power can: (i) outshine pulsars in binaries, (ii) display a
distinctive angular- and time-dependent pattern, and (iii) radiate within large
opening angles. These properties suggest that some binary neutron star mergers
are ideal candidates for multimessenger astronomy.
| [
{
"created": "Tue, 29 Jan 2013 21:03:27 GMT",
"version": "v1"
},
{
"created": "Wed, 24 Jul 2013 16:04:22 GMT",
"version": "v2"
}
] | 2013-08-27 | [
[
"Palenzuela",
"Carlos",
""
],
[
"Lehner",
"Luis",
""
],
[
"Ponce",
"Marcelo",
""
],
[
"Liebling",
"Steven L.",
""
],
[
"Anderson",
"Matthew",
""
],
[
"Neilsen",
"David",
""
],
[
"Motl",
"Patrick",
""
]
] | The late stage of an inspiraling neutron star binary gives rise to strong gravitational wave emission due to its highly dynamic, strong gravity. Moreover, interactions between the stellar magnetospheres can produce considerable electromagnetic radiation. We study this scenario using fully general relativistic, resistive magneto-hydrodynamics simulations. We show that these interactions extract kinetic energy from the system, dissipate heat, and power radiative Poynting flux, as well as develop current sheets. Our results indicate that this power can: (i) outshine pulsars in binaries, (ii) display a distinctive angular- and time-dependent pattern, and (iii) radiate within large opening angles. These properties suggest that some binary neutron star mergers are ideal candidates for multimessenger astronomy. |
2306.06677 | Siddheshwar Kadam | S. A. Kadam, Ninaad P. Thakkar, B. Mishra | Dynamical system analysis in teleparallel gravity with boundary term | 15 pages, 10 figures, 8 tables | Eur. Phys. J. C (2023) 83:809 | 10.1140/epjc/s10052-023-11937-6 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we perform the dynamical system analysis of the cosmological
models framed in the extended teleparallel gravity, the $f (T, B)$ gravity. We
use the mapping, $f(T, B)$ $\rightarrow$-$T$+$\tilde{f}(T, B)$, and define the
dynamical variables to form the autonomous dynamical system. The critical
points are obtained in two well-motivated forms of $f (T, B)$, one that
involves the logarithmic form of the boundary term B, and the other one is the
non-linear form of the boundary term. The position of critical points is shown
in the different evolutionary phases of the Universe such as radiation, matter,
and de-Sitter phase. The stability condition of each of the critical points of
both the models is derived and the behavior of each point has been obtained
mathematically and through the phase portrait. The evolution of standard
density parameters such as radiation ($\Omega_{r}$), matter ($\Omega_{m}$), and
dark energy ($\Omega_{DE}$) are also analyzed. Further to connect with the
present cosmological scenario, the behavior of deceleration and equation of
state parameter both in the dark energy phase ($\omega_{DE}$) and total
($\omega_{tot}$) are shown from the initial condition of the dynamical
variables. The accelerating behaviour has been obtained for both models.
| [
{
"created": "Sun, 11 Jun 2023 13:27:57 GMT",
"version": "v1"
},
{
"created": "Tue, 12 Sep 2023 04:18:42 GMT",
"version": "v2"
}
] | 2023-09-13 | [
[
"Kadam",
"S. A.",
""
],
[
"Thakkar",
"Ninaad P.",
""
],
[
"Mishra",
"B.",
""
]
] | In this paper, we perform the dynamical system analysis of the cosmological models framed in the extended teleparallel gravity, the $f (T, B)$ gravity. We use the mapping, $f(T, B)$ $\rightarrow$-$T$+$\tilde{f}(T, B)$, and define the dynamical variables to form the autonomous dynamical system. The critical points are obtained in two well-motivated forms of $f (T, B)$, one that involves the logarithmic form of the boundary term B, and the other one is the non-linear form of the boundary term. The position of critical points is shown in the different evolutionary phases of the Universe such as radiation, matter, and de-Sitter phase. The stability condition of each of the critical points of both the models is derived and the behavior of each point has been obtained mathematically and through the phase portrait. The evolution of standard density parameters such as radiation ($\Omega_{r}$), matter ($\Omega_{m}$), and dark energy ($\Omega_{DE}$) are also analyzed. Further to connect with the present cosmological scenario, the behavior of deceleration and equation of state parameter both in the dark energy phase ($\omega_{DE}$) and total ($\omega_{tot}$) are shown from the initial condition of the dynamical variables. The accelerating behaviour has been obtained for both models. |
1510.04423 | Mir Faizal | Remo Garattini, Mir Faizal | Cosmological Constant from a Deformation of the Wheeler-DeWitt Equation | 11 pages, 0 figures, Accepted in Nucl. Phys. B | Nucl. Phys. B905, 313 (2016) | 10.1016/j.nuclphysb.2016.02.023 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we consider the Wheeler-DeWitt equation modified by a
deformation of the second quantized canonical commutation relations. Such
modified commutation relations are induced by a Generalized Uncertainty
Principle. Since the Wheeler-DeWitt equation can be related to a
Sturm-Liouville problem where the associated eigenvalue can be interpreted as
the cosmological constant, it is possible to explicitly relate such an
eigenvalue to the deformation parameter of the corresponding Wheeler-DeWitt
equation. The analysis is performed in a Mini-Superspace approach where the
scale factor appears as the only degree of freedom. The deformation of the
Wheeler-DeWitt equation gives rise to a Cosmological Constant even in absence
of matter fields. As a Cosmological Constant cannot exists in absence of the
matter fields in the undeformed Mini-Superspace approach, so the existence of a
non-vanishing Cosmological Constant is a direct consequence of the deformation
by the Generalized Uncertainty Principle. In fact, we are able to demonstrate
that a non-vanishing Cosmological Constant exists even in the deformed flat
space. We also discuss the consequences of this deformation on the big bang
singularity.
| [
{
"created": "Thu, 15 Oct 2015 07:15:39 GMT",
"version": "v1"
},
{
"created": "Tue, 23 Feb 2016 06:28:06 GMT",
"version": "v2"
}
] | 2016-03-14 | [
[
"Garattini",
"Remo",
""
],
[
"Faizal",
"Mir",
""
]
] | In this paper, we consider the Wheeler-DeWitt equation modified by a deformation of the second quantized canonical commutation relations. Such modified commutation relations are induced by a Generalized Uncertainty Principle. Since the Wheeler-DeWitt equation can be related to a Sturm-Liouville problem where the associated eigenvalue can be interpreted as the cosmological constant, it is possible to explicitly relate such an eigenvalue to the deformation parameter of the corresponding Wheeler-DeWitt equation. The analysis is performed in a Mini-Superspace approach where the scale factor appears as the only degree of freedom. The deformation of the Wheeler-DeWitt equation gives rise to a Cosmological Constant even in absence of matter fields. As a Cosmological Constant cannot exists in absence of the matter fields in the undeformed Mini-Superspace approach, so the existence of a non-vanishing Cosmological Constant is a direct consequence of the deformation by the Generalized Uncertainty Principle. In fact, we are able to demonstrate that a non-vanishing Cosmological Constant exists even in the deformed flat space. We also discuss the consequences of this deformation on the big bang singularity. |
2404.09887 | David Kofro\v{n} | David Kofro\v{n} | Kerr black hole in the formalism of isolated horizons | null | Phys. Rev. D 109, 084029 (2024) | 10.1103/PhysRevD.109.084029 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We revise the work of Scholtz, Flandera and G\"urlebeck [Kerr-Newman black
hole in the formalism of isolated horizons, Phys. Rev. D 96, 064024 (2017)]. We
cast the Kerr metric explicitly in the form suitable for the framework of
isolated horizons. We proceed in a geometrical fashion and are capable to
provide the results in a compact closed manner, without any unevaluated
integrals. We also discuss the uniqueness and drawbacks of this construction.
We suggest a new vector field to generate the null geodesic foliation.
| [
{
"created": "Mon, 15 Apr 2024 15:54:34 GMT",
"version": "v1"
}
] | 2024-04-16 | [
[
"Kofroň",
"David",
""
]
] | We revise the work of Scholtz, Flandera and G\"urlebeck [Kerr-Newman black hole in the formalism of isolated horizons, Phys. Rev. D 96, 064024 (2017)]. We cast the Kerr metric explicitly in the form suitable for the framework of isolated horizons. We proceed in a geometrical fashion and are capable to provide the results in a compact closed manner, without any unevaluated integrals. We also discuss the uniqueness and drawbacks of this construction. We suggest a new vector field to generate the null geodesic foliation. |
2202.08655 | Sebastian V\"olkel | Sebastian H. V\"olkel, Nicola Franchini, Enrico Barausse | Theory-agnostic Reconstruction of Potential and Couplings from
Quasi-Normal Modes | 13 pages, 8 figures | Phys. Rev. D 105, 084046, 2022 | 10.1103/PhysRevD.105.084046 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we use a parametrized theory-agnostic approach that connects
the observation of black hole quasi-normal modes with the underlying
perturbation equations, with the goal of reconstructing the potential and the
coupling functions appearing in the latter. The fundamental quasi-normal mode
frequency and its first two overtones are modeled through a second order
expansion in the deviations from general relativity, which are assumed to be
small but otherwise generic. By using a principal component analysis, we
demonstrate that percent-level measurements of the fundamental mode and its
overtones can be used to constrain the effective potential of tensor
perturbations and the coupling functions between tensor modes and ones of
different helicity, without assuming an underlying theory. We also apply our
theory-agnostic reconstruction framework to analyze simulated quasi-normal mode
data produced within specific theories extending general relativity, such as
Chern-Simons gravity.
| [
{
"created": "Thu, 17 Feb 2022 13:37:30 GMT",
"version": "v1"
},
{
"created": "Tue, 26 Apr 2022 13:35:32 GMT",
"version": "v2"
}
] | 2022-04-27 | [
[
"Völkel",
"Sebastian H.",
""
],
[
"Franchini",
"Nicola",
""
],
[
"Barausse",
"Enrico",
""
]
] | In this work, we use a parametrized theory-agnostic approach that connects the observation of black hole quasi-normal modes with the underlying perturbation equations, with the goal of reconstructing the potential and the coupling functions appearing in the latter. The fundamental quasi-normal mode frequency and its first two overtones are modeled through a second order expansion in the deviations from general relativity, which are assumed to be small but otherwise generic. By using a principal component analysis, we demonstrate that percent-level measurements of the fundamental mode and its overtones can be used to constrain the effective potential of tensor perturbations and the coupling functions between tensor modes and ones of different helicity, without assuming an underlying theory. We also apply our theory-agnostic reconstruction framework to analyze simulated quasi-normal mode data produced within specific theories extending general relativity, such as Chern-Simons gravity. |
2010.12578 | Chandra Prakash | Chandra Prakash | Mathematical problems in the Theory of ECO | Shortened the paper by summarizing important results | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A critical overview of the concepts that govern the principles of the
Eternally Collapsing Object (ECO) is entailed in this article. The mathematical
analysis will be dealt to conclude the proof required for the ECO paradigm is
ad-hoc in nature at best. The first section details in rejecting black holes
always considers the possibility of formation of trapped surfaces, so we will
begin our work by looking into "non occurrence of trapped surfaces" then we
analyze Dr. Mitra's indirect claim regarding how $ R = 0$ (inside black hole)
could also be treated as another coordinate singularity. After this a detailed
analysis on the claim that the mass of the Schwarzschild black hole being zero
is in actuality a valid claim or not. The main aim of this article is address
the core issue of whether black holes indeed do exist or is it a consequence of
biases that circumvent common sense over the years. This article aims to bridge
the gap between ECOs and black holes and if at all black holes do exist, which
was vehemently denied by the person whose paper I am reviewing. The analysis
presented here will show us, why ECOs are baseless and can not really be the
solution to black hole problem.
| [
{
"created": "Thu, 22 Oct 2020 19:56:16 GMT",
"version": "v1"
},
{
"created": "Mon, 28 Dec 2020 15:39:31 GMT",
"version": "v2"
},
{
"created": "Sun, 10 Jul 2022 07:32:00 GMT",
"version": "v3"
}
] | 2022-07-12 | [
[
"Prakash",
"Chandra",
""
]
] | A critical overview of the concepts that govern the principles of the Eternally Collapsing Object (ECO) is entailed in this article. The mathematical analysis will be dealt to conclude the proof required for the ECO paradigm is ad-hoc in nature at best. The first section details in rejecting black holes always considers the possibility of formation of trapped surfaces, so we will begin our work by looking into "non occurrence of trapped surfaces" then we analyze Dr. Mitra's indirect claim regarding how $ R = 0$ (inside black hole) could also be treated as another coordinate singularity. After this a detailed analysis on the claim that the mass of the Schwarzschild black hole being zero is in actuality a valid claim or not. The main aim of this article is address the core issue of whether black holes indeed do exist or is it a consequence of biases that circumvent common sense over the years. This article aims to bridge the gap between ECOs and black holes and if at all black holes do exist, which was vehemently denied by the person whose paper I am reviewing. The analysis presented here will show us, why ECOs are baseless and can not really be the solution to black hole problem. |
1806.03691 | Yen Chin Ong | Yen Chin Ong | Zero Mass Remnant as an Asymptotic State of Hawking Evaporation | 5 pages, 4 figures | JHEP 10 (2018) 195 | 10.1007/JHEP10(2018)195 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that although generalized uncertainty principle with negative
parameter allows black holes to evaporate completely, this process takes an
infinite amount time to achieve, resulting in a metastable remnant.
| [
{
"created": "Sun, 10 Jun 2018 17:00:07 GMT",
"version": "v1"
}
] | 2018-11-06 | [
[
"Ong",
"Yen Chin",
""
]
] | We show that although generalized uncertainty principle with negative parameter allows black holes to evaporate completely, this process takes an infinite amount time to achieve, resulting in a metastable remnant. |
0812.4121 | Emilio Santos Corchero | Emilio Santos | Quantum vacuum fluctuations and dark energy | Changed content | Astrophysics and Space Science (2010) 363,7-10 | 10.1007/s10509-009-0204-6 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is shown that the curvature of space-time induced by vacuum fluctuations
of quantum fields should be proportional to the square of Newton's constant
$G$. This offers a possible explanation for the success of the approximation $G
m^6 c^2 h^{-4}$ for the dark energy density, with $m$ being a typical mass of
elementary particles.
| [
{
"created": "Mon, 22 Dec 2008 08:43:04 GMT",
"version": "v1"
},
{
"created": "Wed, 16 Dec 2009 09:09:00 GMT",
"version": "v2"
}
] | 2021-06-16 | [
[
"Santos",
"Emilio",
""
]
] | It is shown that the curvature of space-time induced by vacuum fluctuations of quantum fields should be proportional to the square of Newton's constant $G$. This offers a possible explanation for the success of the approximation $G m^6 c^2 h^{-4}$ for the dark energy density, with $m$ being a typical mass of elementary particles. |
2008.01213 | Vladimir S. Manko | H. Garc\'ia-Compe\'an, V. S. Manko, C. J. Ram\'irez-Valdez | Thermodynamics of two aligned Kerr-Newman black holes | 13 pages, 2 figures | Phys. Rev. D 103, 104001 (2021) | 10.1103/PhysRevD.103.104001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using the notion of thermodynamic length, the first law of thermodynamics is
consistently derived for two binary configurations of equal Kerr-Newman black
holes separated by a massless strut. Like in the electrostatic systems of two
Reissner-Nordstr\"om black holes and stationary vacuum systems of two Kerr
black holes considered earlier, the thermodynamic length $\ell$ turns out to be
defined by the same simple formula $\ell=L\exp(\gamma_0)$, $L$ being the
coordinate length of the strut and $\gamma_0$ the value of the metric function
$\gamma$ on the strut, which permits the elaboration of $\ell$ in a concise
analytic form. The expression of the free energy in the case of two generic
Kerr-Newman black holes is also proposed.
| [
{
"created": "Mon, 3 Aug 2020 21:47:25 GMT",
"version": "v1"
}
] | 2021-06-24 | [
[
"García-Compeán",
"H.",
""
],
[
"Manko",
"V. S.",
""
],
[
"Ramírez-Valdez",
"C. J.",
""
]
] | Using the notion of thermodynamic length, the first law of thermodynamics is consistently derived for two binary configurations of equal Kerr-Newman black holes separated by a massless strut. Like in the electrostatic systems of two Reissner-Nordstr\"om black holes and stationary vacuum systems of two Kerr black holes considered earlier, the thermodynamic length $\ell$ turns out to be defined by the same simple formula $\ell=L\exp(\gamma_0)$, $L$ being the coordinate length of the strut and $\gamma_0$ the value of the metric function $\gamma$ on the strut, which permits the elaboration of $\ell$ in a concise analytic form. The expression of the free energy in the case of two generic Kerr-Newman black holes is also proposed. |
1905.04588 | Alan Coley | A. A. Coley | Spatial Curvature in Cosmology Revisited | This short manuscript summarizes a recent talk and is based on
previously published work | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is necessary to make assumptions in order to derive models to be used for
cosmological predictions and comparison with observational data. In particular,
in standard cosmology the spatial curvature is assumed to be constant and zero
(or at least very small). But there is, as yet, no fully independent constraint
with an appropriate accuracy that gaurentees a value for the magnitude of the
effective normalized spatial curvature $\Omega_{k}$ of less than approximately
$0.01$. Moreover, a small non-zero measurement of $\Omega_{k}$ at such a level
perhaps indicates that the assumptions in the standard model are not satisfied.
It has also been increasingly emphasised that spatial curvature is, in general,
evolving in relativistic cosmological models. We review the current situation,
and conclude that the possibility of such a non-zero value of $\Omega_k$ should
be taken seriously.
| [
{
"created": "Sat, 11 May 2019 20:34:00 GMT",
"version": "v1"
}
] | 2019-05-14 | [
[
"Coley",
"A. A.",
""
]
] | It is necessary to make assumptions in order to derive models to be used for cosmological predictions and comparison with observational data. In particular, in standard cosmology the spatial curvature is assumed to be constant and zero (or at least very small). But there is, as yet, no fully independent constraint with an appropriate accuracy that gaurentees a value for the magnitude of the effective normalized spatial curvature $\Omega_{k}$ of less than approximately $0.01$. Moreover, a small non-zero measurement of $\Omega_{k}$ at such a level perhaps indicates that the assumptions in the standard model are not satisfied. It has also been increasingly emphasised that spatial curvature is, in general, evolving in relativistic cosmological models. We review the current situation, and conclude that the possibility of such a non-zero value of $\Omega_k$ should be taken seriously. |
gr-qc/0104017 | Cenalo Vaz | Cenalo Vaz (U. Algarve) and Louis Witten (U. Cincinnati) | Quantum Black Holes from Quantum Collapse | LaTeX file, 6 pages, 1 figure, Paper re-written into sections, some
references added, some elaborations, conclusions unchanged, to appear in
Physical Review D | Phys.Rev.D64:084005,2001 | 10.1103/PhysRevD.64.084005 | null | gr-qc hep-th | null | The Schwarzschild black hole can be viewed as the special case of the
marginally bound Lema\^\i tre-Tolman-Bondi models of dust collapse which
corresponds to a constant mass function. We have presented a midi-superspace
quantization of this model for an arbitrary mass-function in a separate
publication. In this communication we show that our solution leads both to
Bekenstein's area spectrum for black holes as well as to the black hole
entropy, which, in this context, is naturally interpreted as the loss of
information of the original matter distribution within the collapsing dust
cloud.
| [
{
"created": "Wed, 4 Apr 2001 18:26:08 GMT",
"version": "v1"
},
{
"created": "Wed, 11 Jul 2001 11:40:38 GMT",
"version": "v2"
}
] | 2011-07-19 | [
[
"Vaz",
"Cenalo",
"",
"U. Algarve"
],
[
"Witten",
"Louis",
"",
"U. Cincinnati"
]
] | The Schwarzschild black hole can be viewed as the special case of the marginally bound Lema\^\i tre-Tolman-Bondi models of dust collapse which corresponds to a constant mass function. We have presented a midi-superspace quantization of this model for an arbitrary mass-function in a separate publication. In this communication we show that our solution leads both to Bekenstein's area spectrum for black holes as well as to the black hole entropy, which, in this context, is naturally interpreted as the loss of information of the original matter distribution within the collapsing dust cloud. |
1609.00354 | T. Damour | Thibault Damour | Gravitational scattering, post-Minkowskian approximation and Effective
One-Body theory | 12 pages, 1 figure | Phys. Rev. D 94, 104015 (2016) | 10.1103/PhysRevD.94.104015 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A novel approach to the Effective One-Body description of gravitationally
interacting two-body systems is introduced. This approach is based on the
post-Minkowskian approximation scheme (perturbation theory in G, without
assuming small velocities), and employs a new dictionary focussing on the
functional dependence of the scattering angle on the total energy and the total
angular momentum of the system. Using this approach, we prove to all orders in
v/c two results that were previously known to hold only to a limited
post-Newtonian accuracy: (i) the relativistic gravitational dynamics of a
two-body system is equivalent, at first post-Minkowskian order, to the
relativistic dynamics of an effective test particle moving in a Schwarzschild
metric; and (ii) this equivalence requires the existence of an exactly
quadratic map between the real (relativistic) two-body energy and the
(relativistic) energy of the effective particle. The same energy map is also
shown to apply to the effective one-body description of two masses interacting
via tensor-scalar gravity.
| [
{
"created": "Thu, 1 Sep 2016 19:25:22 GMT",
"version": "v1"
}
] | 2016-11-15 | [
[
"Damour",
"Thibault",
""
]
] | A novel approach to the Effective One-Body description of gravitationally interacting two-body systems is introduced. This approach is based on the post-Minkowskian approximation scheme (perturbation theory in G, without assuming small velocities), and employs a new dictionary focussing on the functional dependence of the scattering angle on the total energy and the total angular momentum of the system. Using this approach, we prove to all orders in v/c two results that were previously known to hold only to a limited post-Newtonian accuracy: (i) the relativistic gravitational dynamics of a two-body system is equivalent, at first post-Minkowskian order, to the relativistic dynamics of an effective test particle moving in a Schwarzschild metric; and (ii) this equivalence requires the existence of an exactly quadratic map between the real (relativistic) two-body energy and the (relativistic) energy of the effective particle. The same energy map is also shown to apply to the effective one-body description of two masses interacting via tensor-scalar gravity. |
1511.05183 | Merav Hadad | Merav Hadad, Levy Rosenblum | The two canonical conjugate pairs at the horizon of a D1D5 black hole | null | Phys. Rev. D 92, 124025 (2015) | 10.1103/PhysRevD.92.124025 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Euclidian opening angle at the $r-t_E$ surface, $\Theta_{r-t_E}$ at the
horizon of a black hole is canonically conjugate to the black hole entropy. We
prove that for a $D1D5$ black hole there exists in addition to this pair,
another canonical pair: the opening angle at the $r-y$ surface, $\Theta_{r-y}$
and a Wald like term $S_{Wr-y}$. This leads to an uncertainty at $\Theta_{r-y}$
which suggests that the surface $r-y$ is actually a superposition of surfaces
with different conical singularities. This corresponds to the same type of
singularities obtained by string theory excitations of a $D1D5$ black hole.
| [
{
"created": "Mon, 16 Nov 2015 21:20:10 GMT",
"version": "v1"
}
] | 2015-12-16 | [
[
"Hadad",
"Merav",
""
],
[
"Rosenblum",
"Levy",
""
]
] | The Euclidian opening angle at the $r-t_E$ surface, $\Theta_{r-t_E}$ at the horizon of a black hole is canonically conjugate to the black hole entropy. We prove that for a $D1D5$ black hole there exists in addition to this pair, another canonical pair: the opening angle at the $r-y$ surface, $\Theta_{r-y}$ and a Wald like term $S_{Wr-y}$. This leads to an uncertainty at $\Theta_{r-y}$ which suggests that the surface $r-y$ is actually a superposition of surfaces with different conical singularities. This corresponds to the same type of singularities obtained by string theory excitations of a $D1D5$ black hole. |
2006.12137 | Sayantani Datta | Sayantani Datta, Anuradha Gupta, Shilpa Kastha, K. G. Arun, B. S.
Sathyaprakash | Tests of general relativity using multiband observations of intermediate
mass binary black hole mergers | 12 pages, 6 figures | Phys. Rev. D 103, 024036 (2021) | 10.1103/PhysRevD.103.024036 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Observation of gravitational waves (GWs) in two different frequency bands is
referred to as multiband GW astronomy. With the planned Laser Interferometric
Space Antenna (LISA) operating in the $10^{-4}-0.1$ Hz range, and third
generation (3G) ground-based detectors such as the Cosmic Explorer (CE) and
Einstein Telescope (ET), operating in the $1$-$10^4$ Hz range, multiband GW
astronomy could be a reality in about a decade. In this paper we present the
potential of multiband observations of intermediate mass binary black holes
(IMBBHs) of component masses ${\sim}10^2$-$10^3\,M_{\odot}$ to test general
relativity (GR). We show that mutiband observations of IMBBHs would permit
multiparameter tests of GR-tests where more than one post-Newtonian (PN)
coefficient is simultaneously measured yielding more rigorous constraints on
possible modifications to GR. We also find that the improvement due to
multibanding can often be much larger than the best of the bounds from either
of the two observatories. The origin of this result, as we shall demonstrate,
can be traced to the lifting of degeneracies among the various parameters when
the information from LISA and 3G are taken together. We obtain the best
multiband bounds for an IMBBH with a total redshifted mass of $200\,M_{\odot}$
and a mass ratio of 2. For single-parameter tests, this system at 1 Gpc would
allow us to constrain the deviations on all the PN coefficients to below $10\%$
and derive simultaneous bounds on the first seven PN coefficients to below
$50\%$ (with low spins).
| [
{
"created": "Mon, 22 Jun 2020 10:55:12 GMT",
"version": "v1"
},
{
"created": "Tue, 16 Mar 2021 07:10:50 GMT",
"version": "v2"
}
] | 2021-03-17 | [
[
"Datta",
"Sayantani",
""
],
[
"Gupta",
"Anuradha",
""
],
[
"Kastha",
"Shilpa",
""
],
[
"Arun",
"K. G.",
""
],
[
"Sathyaprakash",
"B. S.",
""
]
] | Observation of gravitational waves (GWs) in two different frequency bands is referred to as multiband GW astronomy. With the planned Laser Interferometric Space Antenna (LISA) operating in the $10^{-4}-0.1$ Hz range, and third generation (3G) ground-based detectors such as the Cosmic Explorer (CE) and Einstein Telescope (ET), operating in the $1$-$10^4$ Hz range, multiband GW astronomy could be a reality in about a decade. In this paper we present the potential of multiband observations of intermediate mass binary black holes (IMBBHs) of component masses ${\sim}10^2$-$10^3\,M_{\odot}$ to test general relativity (GR). We show that mutiband observations of IMBBHs would permit multiparameter tests of GR-tests where more than one post-Newtonian (PN) coefficient is simultaneously measured yielding more rigorous constraints on possible modifications to GR. We also find that the improvement due to multibanding can often be much larger than the best of the bounds from either of the two observatories. The origin of this result, as we shall demonstrate, can be traced to the lifting of degeneracies among the various parameters when the information from LISA and 3G are taken together. We obtain the best multiband bounds for an IMBBH with a total redshifted mass of $200\,M_{\odot}$ and a mass ratio of 2. For single-parameter tests, this system at 1 Gpc would allow us to constrain the deviations on all the PN coefficients to below $10\%$ and derive simultaneous bounds on the first seven PN coefficients to below $50\%$ (with low spins). |
1102.3781 | Evan Ochsner | The LIGO Scientific Collaboration, the Virgo Collaboration: J. Abadie,
B. P. Abbott, R. Abbott, M. Abernathy, T. Accadia, F. Acernese, C. Adams, R.
Adhikari, P. Ajith, B. Allen, G. S. Allen, E. Amador Ceron, R. S. Amin, S. B.
Anderson, W. G. Anderson, F. Antonucci, M. A. Arain, M. C. Araya, M.
Aronsson, Y. Aso, S. M. Aston, P. Astone, D. Atkinson, P. Aufmuth, C.
Aulbert, S. Babak, P. Baker, G. Ballardin, T. Ballinger, S. Ballmer, D.
Barker, S. Barnum, F. Barone, B. Barr, P. Barriga, L. Barsotti, M. Barsuglia,
M. A. Barton, I. Bartos, R. Bassiri, M. Bastarrika, J. Bauchrowitz, Th. S.
Bauer, B. Behnke, M.G. Beker, A. Belletoile, M. Benacquista, A. Bertolini, J.
Betzwieser, N. Beveridge, P. T. Beyersdorf, I. A. Bilenko, G. Billingsley, J.
Birch, S. Birindelli, R. Biswas, M. Bitossi, M. A. Bizouard, E. Black, J. K.
Blackburn, L. Blackburn, D. Blair, B. Bland, M. Blom, C. Boccara, O. Bock, T.
P. Bodiya, R. Bondarescu, F. Bondu, L. Bonelli, R. Bonnand, R. Bork, M. Born,
V. Boschi, S. Bose, L. Bosi, B. Bouhou, M. Boyle, S. Braccini, C. Bradaschia,
P. R. Brady, V. B. Braginsky, J. E. Brau, J. Breyer, D. O. Bridges, A.
Brillet, M. Brinkmann, V. Brisson, M. Britzger, A. F. Brooks, D. A. Brown, R.
Budzy\'nski, T. Bulik, H. J. Bulten, A. Buonanno, J. Burguet-Castell, O.
Burmeister, D. Buskulic, C. Buy, R. L. Byer, L. Cadonati, G. Cagnoli, J.
Cain, E. Calloni, J. B. Camp, E. Campagna, P. Campsie, J. Cannizzo, K.
Cannon, B. Canuel, J. Cao, C. Capano, F. Carbognani, S. Caride, S. Caudill,
M. Cavaglia`, F. Cavalier, R. Cavalieri, G. Cella, C. Cepeda, E. Cesarini, O.
Chaibi, T. Chalermsongsak, E. Chalkley, P. Charlton, E. Chassande-Mottin, S.
Chelkowski, Y. Chen, A. Chincarini, N. Christensen, S. S. Y. Chua, C. T. Y.
Chung, D. Clark, J. Clark, J. H. Clayton, F. Cleva, E. Coccia, C. N.
Colacino, J. Colas, A. Colla, M. Colombini, R. Conte, D. Cook, T. R. Corbitt,
N. Cornish, A. Corsi, C. A. Costa, J.-P. Coulon, D. M. Coward, D. C. Coyne,
J. D. E. Creighton, T. D. Creighton, A. M. Cruise, R. M. Culter, A. Cumming,
L. Cunningham, E. Cuoco, K. Dahl, S. L. Danilishin, R. Dannenberg, S.
D'Antonio, K. Danzmann, K. Das, V. Dattilo, B. Daudert, M. Davier, G. Davies,
A. Davis, E. J. Daw, R. Day, T. Dayanga, R. De Rosa, D. DeBra, G. Debreczeni,
J. Degallaix, M. del Prete, V. Dergachev, R. DeRosa, R. DeSalvo, P. Devanka,
S. Dhurandhar, L. Di Fiore, A. Di Lieto, I. Di Palma, M. Di Paolo Emilio, A.
Di Virgilio, M. D\'iaz, A. Dietz, F. Donovan, K. L. Dooley, E. E. Doomes, S.
Dorsher, E. S. D. Douglas, M. Drago, R. W. P. Drever, J. C. Driggers, J.
Dueck, J.-C. Dumas, T. Eberle, M. Edgar, M. Edwards, A. Effler, P. Ehrens, G.
Ely, R. Engel, T. Etzel, M. Evans, T. Evans, V. Fafone, S. Fairhurst, Y. Fan,
B. F. Farr, D. Fazi, H. Fehrmann, D. Feldbaum, I. Ferrante, F. Fidecaro, L.
S. Finn, I. Fiori, R. Flaminio, M. Flanigan, K. Flasch, S. Foley, C. Forrest,
E. Forsi, L. A. Forte, N. Fotopoulos, J.-D. Fournier, J. Franc, S. Frasca, F.
Frasconi, M. Frede, M. Frei, Z. Frei, A. Freise, R. Frey, T. T. Fricke, D.
Friedrich, P. Fritschel, V. V. Frolov, P. Fulda, M. Fyffe, M. Galimberti, L.
Gammaitoni, J. A. Garofoli, F. Garufi, M. E. G\'asp\'ar, G. Gemme, E. Genin,
A. Gennai, I. Gholami, S. Ghosh, J. A. Giaime, S. Giampanis, K. D. Giardina,
A. Giazotto, C. Gill, E. Goetz, L. M. Goggin, G. Gonz\'alez, M. L.
Gorodetsky, S. Go{\ss}ler, R. Gouaty, C. Graef, M. Granata, A. Grant, S.
Gras, C. Gray, R. J. S. Greenhalgh, A. M. Gretarsson, C. Greverie, R. Grosso,
H. Grote, S. Grunewald, G. M. Guidi, E. K. Gustafson, R. Gustafson, B. Hage,
P. Hall, J. M. Hallam, D. Hammer, G. Hammond, J. Hanks, C. Hanna, J. Hanson,
J. Harms, G. M. Harry, I. W. Harry, E. D. Harstad, K. Haughian, K. Hayama,
J.-F. Hayau, T. Hayler, J. Heefner, H. Heitmann, P. Hello, I. S. Heng, A. W.
Heptonstall, M. Hewitson, S. Hild, E. Hirose, D. Hoak, K. A. Hodge, K. Holt,
D. J. Hosken, J. Hough, E. J. Howell, D. Hoyland, D. Huet, B. Hughey, S.
Husa, S. H. Huttner, T. Huynh-Dinh, D. R. Ingram, R. Inta, T. Isogai, A.
Ivanov, P. Jaranowski, W. W. Johnson, D. I. Jones, G. Jones, R. Jones, L. Ju,
P. Kalmus, V. Kalogera, S. Kandhasamy, J. B. Kanner, E. Katsavounidis, K.
Kawabe, S. Kawamura, F. Kawazoe, W. Kells, D. G. Keppel, A. Khalaidovski, F.
Y. Khalili, E. A. Khazanov, H. Kim, P. J. King, D. L. Kinzel, J. S. Kissel,
S. Klimenko, V. Kondrashov, R. Kopparapu, S. Koranda, I. Kowalska, D. Kozak,
T. Krause, V. Kringel, S. Krishnamurthy, B. Krishnan, A. Kr\'olak, G. Kuehn,
J. Kullman, R. Kumar, P. Kwee, M. Landry, M. Lang, B. Lantz, N. Lastzka, A.
Lazzarini, P. Leaci, J. Leong, I. Leonor, N. Leroy, N. Letendre, J. Li, T. G.
F. Li, N. Liguori, H. Lin, P. E. Lindquist, N. A. Lockerbie, D. Lodhia, M.
Lorenzini, V. Loriette, M. Lormand, G. Losurdo, P. Lu, J. Luan, M. Lubinski,
A. Lucianetti, H. L\"uck, A. D. Lundgren, B. Machenschalk, M. MacInnis, M.
Mageswaran, K. Mailand, E. Majorana, C. Mak, I. Maksimovic, N. Man, I.
Mandel, V. Mandic, M. Mantovani, F. Marchesoni, F. Marion, S. M\'arka, Z.
M\'arka, E. Maros, J. Marque, F. Martelli, I. W. Martin, R. M. Martin, J. N.
Marx, K. Mason, A. Masserot, F. Matichard, L. Matone, R. A. Matzner, N.
Mavalvala, R. McCarthy, D. E. McClelland, S. C. McGuire, G. McIntyre, G.
McIvor, D. J. A. McKechan, G. Meadors, M. Mehmet, T. Meier, A. Melatos, A. C.
Melissinos, G. Mendell, D. F. Men\'endez, R. A. Mercer, L. Merill, S.
Meshkov, C. Messenger, M. S. Meyer, H. Miao, C. Michel, L. Milano, J. Miller,
Y. Minenkov, Y. Mino, S. Mitra, V. P. Mitrofanov, G. Mitselmakher, R.
Mittleman, B. Moe, M. Mohan, S. D. Mohanty, S. R. P. Mohapatra, D. Moraru, J.
Moreau, G. Moreno, N. Morgado, A. Morgia, T. Morioka, K. Mors, S. Mosca, V.
Moscatelli, K. Mossavi, B. Mours, C. M. Mow-Lowry, G. Mueller, S. Mukherjee,
A. Mullavey, H. M\"uller-Ebhardt, J. Munch, P. G. Murray, T. Nash, R.
Nawrodt, J. Nelson, I. Neri, G. Newton, A. Nishizawa, F. Nocera, D. Nolting,
E. Ochsner, J. O'Dell, G. H. Ogin, R. G. Oldenburg, B. O'Reilly, R.
O'Shaughnessy, C. Osthelder, D. J. Ottaway, R. S. Ottens, H. Overmier, B. J.
Owen, A. Page, G. Pagliaroli, L. Palladino, C. Palomba, Y. Pan, C. Pankow, F.
Paoletti, M. A. Papa, S. Pardi, M. Pareja, M. Parisi, A. Pasqualetti, R.
Passaquieti, D. Passuello, P. Patel, D. Pathak, M. Pedraza, L. Pekowsky, S.
Penn, C. Peralta, A. Perreca, G. Persichetti, M. Pichot, M. Pickenpack, F.
Piergiovanni, M. Pietka, L. Pinard, I. M. Pinto, M. Pitkin, H. J. Pletsch, M.
V. Plissi, R. Poggiani, F. Postiglione, M. Prato, V. Predoi, L. R. Price, M.
Prijatelj, M. Principe, R. Prix, G. A. Prodi, L. Prokhorov, O. Puncken, M.
Punturo, P. Puppo, V. Quetschke, F. J. Raab, D. S. Rabeling, I. R\'acz, T.
Radke, H. Radkins, P. Raffai, M. Rakhmanov, B. Rankins, P. Rapagnani, V.
Raymond, V. Re, C. M. Reed, T. Reed, T. Regimbau, S. Reid, D. H. Reitze, F.
Ricci, R. Riesen, K. Riles, P. Roberts, N. A. Robertson, F. Robinet, C.
Robinson, E. L. Robinson, A. Rocchi, S. Roddy, L. Rolland, J. Rollins, J. D.
Romano, R. Romano, J. H. Romie, D. Rosi\'nska, C. R\"over, S. Rowan, A.
R\"udiger, P. Ruggi, K. Ryan, S. Sakata, M. Sakosky, F. Salemi, L. Sammut, L.
Sancho de la Jordana, V. Sandberg, V. Sannibale, L. Santamar\'ia, G.
Santostasi, S. Saraf, B. Sassolas, B. S. Sathyaprakash, S. Sato, M.
Satterthwaite, P. R. Saulson, R. Savage, R. Schilling, R. Schnabel, R. M. S.
Schofield, B. Schulz, B. F. Schutz, P. Schwinberg, J. Scott, S. M. Scott, A.
C. Searle, F. Seifert, D. Sellers, A. S. Sengupta, D. Sentenac, A. Sergeev,
D. A. Shaddock, B. Shapiro, P. Shawhan, D. H. Shoemaker, A. Sibley, X.
Siemens, D. Sigg, A. Singer, A. M. Sintes, G. Skelton, B. J. J. Slagmolen, J.
Slutsky, J. R. Smith, M. R. Smith, N. D. Smith, K. Somiya, B. Sorazu, F. C.
Speirits, L. Sperandio, A. J. Stein, L. C. Stein, S. Steinlechner, S.
Steplewski, A. Stochino, R. Stone, K. A. Strain, S. Strigin, A. S. Stroeer,
R. Sturani, A. L. Stuver, T. Z. Summerscales, M. Sung, S. Susmithan, P. J.
Sutton, B. Swinkels, G. P. Szokoly, M. Tacca, D. Talukder, D. B. Tanner, S.
P. Tarabrin, J. R. Taylor, R. Taylor, P. Thomas, K. A. Thorne, K. S. Thorne,
E. Thrane, A. Th\"uring, C. Titsler, K. V. Tokmakov, A. Toncelli, M. Tonelli,
O. Torre, C. Torres, C. I. Torrie, E. Tournefier, F. Travasso, G. Traylor, M.
Trias, K. Tseng, L. Turner, D. Ugolini, K. Urbanek, H. Vahlbruch, B.
Vaishnav, G. Vajente, M. Vallisneri, J. F. J. van den Brand, C. Van Den
Broeck, S. van der Putten, M. V. van der Sluys, A. A. van Veggel, S. Vass, M.
Vasuth, R. Vaulin, M. Vavoulidis, A. Vecchio, G. Vedovato, J. Veitch, P. J.
Veitch, C. Veltkamp, D. Verkindt, F. Vetrano, A. Vicer\'e, A. E. Villar,
J.-Y. Vinet, H. Vocca, C. Vorvick, S. P. Vyachanin, S. J. Waldman, L.
Wallace, A. Wanner, R. L. Ward, M. Was, P. Wei, M. Weinert, A. J. Weinstein,
R. Weiss, L. Wen, S. Wen, P. Wessels, M. West, T. Westphal, K. Wette, J. T.
Whelan, S. E. Whitcomb, D. White, B. F. Whiting, C. Wilkinson, P. A. Willems,
L. Williams, B. Willke, L. Winkelmann, W. Winkler, C. C. Wipf, A. G. Wiseman,
G. Woan, R. Wooley, J. Worden, I. Yakushin, H. Yamamoto, K. Yamamoto, D.
Yeaton-Massey, S. Yoshida, P. Yu, M. Yvert, M. Zanolin, L. Zhang, Z. Zhang,
C. Zhao, N. Zotov, M. E. Zucker, and J. Zweizig | Search for gravitational waves from binary black hole inspiral, merger
and ringdown | 19 pages, 3 figures | Phys.Rev.D83:122005,2011 | 10.1103/PhysRevD.83.122005 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present the first modeled search for gravitational waves using the
complete binary black hole gravitational waveform from inspiral through the
merger and ringdown for binaries with negligible component spin. We searched
approximately 2 years of LIGO data taken between November 2005 and September
2007 for systems with component masses of 1-99 solar masses and total masses of
25-100 solar masses. We did not detect any plausible gravitational-wave signals
but we do place upper limits on the merger rate of binary black holes as a
function of the component masses in this range. We constrain the rate of
mergers for binary black hole systems with component masses between 19 and 28
solar masses and negligible spin to be no more than 2.0 per Mpc^3 per Myr at
90% confidence.
| [
{
"created": "Fri, 18 Feb 2011 08:39:48 GMT",
"version": "v1"
}
] | 2012-08-27 | [
[
"The LIGO Scientific Collaboration",
"",
""
],
[
"the Virgo Collaboration",
"",
""
],
[
"Abadie",
"J.",
""
],
[
"Abbott",
"B. P.",
""
],
[
"Abbott",
"R.",
""
],
[
"Abernathy",
"M.",
""
],
[
"Accadia",
"T.",
... | We present the first modeled search for gravitational waves using the complete binary black hole gravitational waveform from inspiral through the merger and ringdown for binaries with negligible component spin. We searched approximately 2 years of LIGO data taken between November 2005 and September 2007 for systems with component masses of 1-99 solar masses and total masses of 25-100 solar masses. We did not detect any plausible gravitational-wave signals but we do place upper limits on the merger rate of binary black holes as a function of the component masses in this range. We constrain the rate of mergers for binary black hole systems with component masses between 19 and 28 solar masses and negligible spin to be no more than 2.0 per Mpc^3 per Myr at 90% confidence. |
gr-qc/0203068 | Randall Guedes Teixeira | R. Casana, B. M. Pimentel (Sao Paulo, IFT), J. T. Lunardi (Ponta
Grossa State U.) and R. G. Teixeira (Sao Judas Tadeu U.) | Spin 1 fields in Riemann-Cartan space-times "via" Duffin-Kemmer-Petiau
theory | 8 pages, no figures, revtex. Dedicated to Professor Gerhard Wilhelm
Bund on the occasion of his 70th birthday. To appear in Gen. Rel. Grav.
Equations numbering corrected. References updated | Gen.Rel.Grav. 34 (2002) 1941-1951 | 10.1023/A:1020732611995 | null | gr-qc | null | We consider massive spin 1 fields, in Riemann-Cartan space-times, described
by Duffin-Kemmer-Petiau theory. We show that this approach induces a coupling
between the spin 1 field and the space-time torsion which breaks the usual
equivalence with the Proca theory, but that such equivalence is preserved in
the context of the Teleparallel Equivalent of General Relativity.
| [
{
"created": "Wed, 20 Mar 2002 20:48:49 GMT",
"version": "v1"
},
{
"created": "Mon, 23 Sep 2002 16:05:00 GMT",
"version": "v2"
}
] | 2020-05-19 | [
[
"Casana",
"R.",
"",
"Sao Paulo, IFT"
],
[
"Pimentel",
"B. M.",
"",
"Sao Paulo, IFT"
],
[
"Lunardi",
"J. T.",
"",
"Ponta\n Grossa State U."
],
[
"Teixeira",
"R. G.",
"",
"Sao Judas Tadeu U."
]
] | We consider massive spin 1 fields, in Riemann-Cartan space-times, described by Duffin-Kemmer-Petiau theory. We show that this approach induces a coupling between the spin 1 field and the space-time torsion which breaks the usual equivalence with the Proca theory, but that such equivalence is preserved in the context of the Teleparallel Equivalent of General Relativity. |
gr-qc/0410082 | Donato Bini | Donato Bini, Fernando de Felice, Andrea Geralico | Spinning test particles and clock effect in Schwarzschild spacetime | IOP macros, eps figures n. 2, to appear on Classical and Quantum
gravity, 2004 | Class.Quant.Grav.21:5427-5440,2004 | 10.1088/0264-9381/21/23/009 | null | gr-qc | null | We study the behaviour of spinning test particles in the Schwarzschild
spacetime. Using Mathisson-Papapetrou equations of motion we confine our
attention to spatially circular orbits and search for observable effects which
could eventually discriminate among the standard supplementary conditions
namely the Corinaldesi-Papapetrou, Pirani and Tulczyjew. We find that if the
world line chosen for the multipole reduction and whose unit tangent we denote
as $U$ is a circular orbit then also the generalized momentum $P$ of the
spinning test particle is tangent to a circular orbit even though $P$ and $U$
are not parallel four-vectors. These orbits are shown to exist because the spin
induced tidal forces provide the required acceleration no matter what
supplementary condition we select. Of course, in the limit of a small spin the
particle's orbit is close of being a circular geodesic and the (small)
deviation of the angular velocities from the geodesic values can be of an
arbitrary sign, corresponding to the possible spin-up and spin-down alignment
to the z-axis. When two spinning particles orbit around a gravitating source in
opposite directions, they make one loop with respect to a given static observer
with different arrival times. This difference is termed clock effect. We find
that a nonzero gravitomagnetic clock effect appears for oppositely orbiting
both spin-up or spin-down particles even in the Schwarzschild spacetime. This
allows us to establish a formal analogy with the case of (spin-less) geodesics
on the equatorial plane of the Kerr spacetime. This result can be verified
experimentally.
| [
{
"created": "Mon, 18 Oct 2004 13:44:42 GMT",
"version": "v1"
}
] | 2011-07-19 | [
[
"Bini",
"Donato",
""
],
[
"de Felice",
"Fernando",
""
],
[
"Geralico",
"Andrea",
""
]
] | We study the behaviour of spinning test particles in the Schwarzschild spacetime. Using Mathisson-Papapetrou equations of motion we confine our attention to spatially circular orbits and search for observable effects which could eventually discriminate among the standard supplementary conditions namely the Corinaldesi-Papapetrou, Pirani and Tulczyjew. We find that if the world line chosen for the multipole reduction and whose unit tangent we denote as $U$ is a circular orbit then also the generalized momentum $P$ of the spinning test particle is tangent to a circular orbit even though $P$ and $U$ are not parallel four-vectors. These orbits are shown to exist because the spin induced tidal forces provide the required acceleration no matter what supplementary condition we select. Of course, in the limit of a small spin the particle's orbit is close of being a circular geodesic and the (small) deviation of the angular velocities from the geodesic values can be of an arbitrary sign, corresponding to the possible spin-up and spin-down alignment to the z-axis. When two spinning particles orbit around a gravitating source in opposite directions, they make one loop with respect to a given static observer with different arrival times. This difference is termed clock effect. We find that a nonzero gravitomagnetic clock effect appears for oppositely orbiting both spin-up or spin-down particles even in the Schwarzschild spacetime. This allows us to establish a formal analogy with the case of (spin-less) geodesics on the equatorial plane of the Kerr spacetime. This result can be verified experimentally. |
2110.04846 | Mehdi Shokri | J. Sadeghi, M. Shokri, S. Noori Gashti, B. Pourhassan and P. Rudra | Traversable wormhole in logarithmic $f(R)$ gravity by various shape and
redshift functions | 16 pages, 4 figures, accepted version of paper | International Journal of Modern Physics D, 2022 | 10.1142/S0218271822500195 | Vol. 31, No. 03, 2250019 | gr-qc | http://creativecommons.org/publicdomain/zero/1.0/ | We study the traversable wormhole solutions for a logarithmic corrected
$f(R)$ model by considering two different statements of shape $b(r)$ and
redshift $\Phi(r)$ functions. We calculate the parameters of the model
including energy density $\rho$, tangential pressure $P_{t}$ and radial
pressure $P_{r}$ for the corresponding forms of the functions. Then, we
investigate different energy conditions such as null energy condition, weak
energy condition, dominant energy condition and strong energy condition for our
considered cases. Finally, we explain the satisfactory conditions of energy of
the models by related plots.
| [
{
"created": "Sun, 10 Oct 2021 16:26:45 GMT",
"version": "v1"
},
{
"created": "Tue, 9 Nov 2021 16:12:35 GMT",
"version": "v2"
},
{
"created": "Sat, 26 Mar 2022 08:29:22 GMT",
"version": "v3"
}
] | 2022-03-29 | [
[
"Sadeghi",
"J.",
""
],
[
"Shokri",
"M.",
""
],
[
"Gashti",
"S. Noori",
""
],
[
"Pourhassan",
"B.",
""
],
[
"Rudra",
"P.",
""
]
] | We study the traversable wormhole solutions for a logarithmic corrected $f(R)$ model by considering two different statements of shape $b(r)$ and redshift $\Phi(r)$ functions. We calculate the parameters of the model including energy density $\rho$, tangential pressure $P_{t}$ and radial pressure $P_{r}$ for the corresponding forms of the functions. Then, we investigate different energy conditions such as null energy condition, weak energy condition, dominant energy condition and strong energy condition for our considered cases. Finally, we explain the satisfactory conditions of energy of the models by related plots. |
gr-qc/0003047 | Sang Pyo Kim | Donsu Bak, Sang Pyo Kim, Sung Ku Kim, Kwang-Sup Soh, Jae Hyung Yee | Black Hole Decay and Quantum Instantons | RevTex, 7 pages, no figure; The wave functions of gr-qc/9912115 are
newly interpreted as quantum instantons describing a black hole decay.
Replaced by the version to be published in Phys. Rev. D, in which the
boundary condition on the apparent horizon is clarified | Phys.Rev.D62:047504,2000 | 10.1103/PhysRevD.62.047504 | null | gr-qc | null | We study the analytic structure of the S-matrix which is obtained from the
reduced Wheeler-DeWitt wave function describing spherically symmetric
gravitational collapse of massless scalar fields. The complex simple poles in
the S-matrix lead to the wave functions that satisfy the same boundary
condition as quasi-normal modes of a black hole, and correspond to the bounded
states of the Euclidean Wheeler-DeWitt equation. These wave function are
interpreted as quantum instantons.
| [
{
"created": "Mon, 13 Mar 2000 09:27:29 GMT",
"version": "v1"
},
{
"created": "Sat, 6 May 2000 01:10:16 GMT",
"version": "v2"
}
] | 2010-03-02 | [
[
"Bak",
"Donsu",
""
],
[
"Kim",
"Sang Pyo",
""
],
[
"Kim",
"Sung Ku",
""
],
[
"Soh",
"Kwang-Sup",
""
],
[
"Yee",
"Jae Hyung",
""
]
] | We study the analytic structure of the S-matrix which is obtained from the reduced Wheeler-DeWitt wave function describing spherically symmetric gravitational collapse of massless scalar fields. The complex simple poles in the S-matrix lead to the wave functions that satisfy the same boundary condition as quasi-normal modes of a black hole, and correspond to the bounded states of the Euclidean Wheeler-DeWitt equation. These wave function are interpreted as quantum instantons. |
1205.3542 | Khaled Saaidi | Khaled Saaidi | (Non-) geodesic motion in chameleon Brans Dicke model | 7 pages, no figures | Astrophys. Space Sci. 345 (2013) 431 | 10.1007/s10509-013-1407-4 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Based on \cite{16}, we assume there is a non-minimal coupling between the
scalar field and matter in Brans-Dicke model. We analyzes the motion of
different matter such as, massless scalar field, photon, massless perfect fluid
(dust), massive perfect fluid and point particle matter in this theory. We show
that the motion of massless scalar field and photon can satisfy null geodesic
motion only in high frequency limit. Also we find that the motion of the dust
and massive perfect fluid is geodesic for $L_m=-P$ and is non-geodesic for
$L_m=\R$. Finally, we study the motion of point particle and show that the
motion of this kind of matter is non-geodesic.
| [
{
"created": "Wed, 16 May 2012 02:21:00 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Jan 2014 12:29:24 GMT",
"version": "v2"
}
] | 2014-01-17 | [
[
"Saaidi",
"Khaled",
""
]
] | Based on \cite{16}, we assume there is a non-minimal coupling between the scalar field and matter in Brans-Dicke model. We analyzes the motion of different matter such as, massless scalar field, photon, massless perfect fluid (dust), massive perfect fluid and point particle matter in this theory. We show that the motion of massless scalar field and photon can satisfy null geodesic motion only in high frequency limit. Also we find that the motion of the dust and massive perfect fluid is geodesic for $L_m=-P$ and is non-geodesic for $L_m=\R$. Finally, we study the motion of point particle and show that the motion of this kind of matter is non-geodesic. |
1708.09670 | Herve Bergeron | Herv\'e Bergeron, Ewa Czuchry, Przemys{\l}aw Ma{\l}kiewicz | Coherent states quantization and affine symmetry in quantum models of
gravitational singularities | 27 pages, 10 figures, Contribution to the Proceedings of the
conference "Coherent States and their Applications: A Contemporary Panorama",
November 14-18th, 2016, Centre International de Rencontres Scientifiques,
Luminy, Marseille, France | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We employ the framework of affine covariant quantization and associated
semiclassical portrait to address two main issues in the domain of quantum
gravitational systems: (i) the fate of singularities and (ii) the lack of
external time. Our discussion is based on finite-dimensional, symmetry-reduced
cosmological models. We show that the affine quantization of the cosmological
dynamics removes the classical singularity and univocally establishes a unitary
evolution. The semiclassical portrait based on the affine coherent states
exhibits a big bounce replacing the big-bang singularity. As a particularly
interesting application, we derive and study a unitary quantum dynamics of the
spatially homogenous, closed model, the Mixmaster universe. At the classical
level it undergoes an infinite number of oscillations before collapsing into a
big-crunch singularity. At the quantum level the singularity is shown to be
replaced by adiabatic and nonadiabatic bounces. As another application, we
consider the problem of time. We derive semiclassical portraits of quantum
dynamics of the Friedman universe with respect to various internal degrees of
freedom. Next we compare them and discuss the nature of quantum evolution of
the gravitational field.
| [
{
"created": "Thu, 31 Aug 2017 11:21:39 GMT",
"version": "v1"
},
{
"created": "Mon, 18 Sep 2017 14:17:41 GMT",
"version": "v2"
}
] | 2017-09-19 | [
[
"Bergeron",
"Hervé",
""
],
[
"Czuchry",
"Ewa",
""
],
[
"Małkiewicz",
"Przemysław",
""
]
] | We employ the framework of affine covariant quantization and associated semiclassical portrait to address two main issues in the domain of quantum gravitational systems: (i) the fate of singularities and (ii) the lack of external time. Our discussion is based on finite-dimensional, symmetry-reduced cosmological models. We show that the affine quantization of the cosmological dynamics removes the classical singularity and univocally establishes a unitary evolution. The semiclassical portrait based on the affine coherent states exhibits a big bounce replacing the big-bang singularity. As a particularly interesting application, we derive and study a unitary quantum dynamics of the spatially homogenous, closed model, the Mixmaster universe. At the classical level it undergoes an infinite number of oscillations before collapsing into a big-crunch singularity. At the quantum level the singularity is shown to be replaced by adiabatic and nonadiabatic bounces. As another application, we consider the problem of time. We derive semiclassical portraits of quantum dynamics of the Friedman universe with respect to various internal degrees of freedom. Next we compare them and discuss the nature of quantum evolution of the gravitational field. |
2303.07380 | Matt Visser | Joshua Baines (Victoria University of Wellington) and Matt Visser
(Victoria University of Wellington) | Killing horizons and surface gravities for a well-behaved three-function
generalisation of the Kerr spacetime | V1: 24 pages, no figures. V2: Two references added, minor changes in
presentation. No changes in the physics. V3: Now 28 pages. Extra discussion
and references; no changes in the physics. This version closely resembles the
published version | Universe 9 # 5 (2023) 223 | 10.3390/universe9050223 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Thanks to the recent advent of the event horizon telescope (EHT), we now have
the opportunity to test the physical ramifications of the strong-field
near-horizon regime for astrophysical black holes. Herein, emphasizing the
trade-off between tractability and generality, the authors discuss a
particularly powerful three-function distortion of the Kerr spacetime,
depending on three arbitrary functions of the radial coordinate $r$, which on
the one hand can be fit to future observational data, and on the other hand is
sufficiently general so as to encompass an extremely wide class of theoretical
models. In all of these spacetimes, both the timelike Hamilton--Jacobi
(geodesic) and massive Klein--Gordon (wave) equations separate, and the
spacetime geometry is asymptotically Kerr; hence these spacetimes are
well-suited to modelling real astrophysical black holes. The authors then prove
the existence of Killing horizons for this entire class of spacetimes, and give
tractable expressions for the angular velocities, areas, and surface gravities
of these horizons. We emphasize the validity of rigidity results and zeroth
laws for these horizons.
| [
{
"created": "Mon, 13 Mar 2023 18:01:09 GMT",
"version": "v1"
},
{
"created": "Wed, 29 Mar 2023 06:39:04 GMT",
"version": "v2"
},
{
"created": "Mon, 15 May 2023 06:12:51 GMT",
"version": "v3"
}
] | 2023-05-16 | [
[
"Baines",
"Joshua",
"",
"Victoria University of Wellington"
],
[
"Visser",
"Matt",
"",
"Victoria University of Wellington"
]
] | Thanks to the recent advent of the event horizon telescope (EHT), we now have the opportunity to test the physical ramifications of the strong-field near-horizon regime for astrophysical black holes. Herein, emphasizing the trade-off between tractability and generality, the authors discuss a particularly powerful three-function distortion of the Kerr spacetime, depending on three arbitrary functions of the radial coordinate $r$, which on the one hand can be fit to future observational data, and on the other hand is sufficiently general so as to encompass an extremely wide class of theoretical models. In all of these spacetimes, both the timelike Hamilton--Jacobi (geodesic) and massive Klein--Gordon (wave) equations separate, and the spacetime geometry is asymptotically Kerr; hence these spacetimes are well-suited to modelling real astrophysical black holes. The authors then prove the existence of Killing horizons for this entire class of spacetimes, and give tractable expressions for the angular velocities, areas, and surface gravities of these horizons. We emphasize the validity of rigidity results and zeroth laws for these horizons. |
gr-qc/9402042 | Misao Sasaki | Misao Sasaki | Post-Newtonian Expansion of the Ingoing-Wave Regge-Wheeler Function | 31 pages, KUNS 1246 | Prog.Theor.Phys.92:17-36,1994 | 10.1143/PTP.92.17 | null | gr-qc | null | We present a method of post-Newtonian expansion to solve the homogeneous
Regge-Wheeler equation which describes gravitational waves on the Schwarzschild
spacetime. The advantage of our method is that it allows a systematic iterative
analysis of the solution. Then we obtain the Regge-Wheeler function which is
purely ingoing at the horizon in closed analytic form, with accuracy required
to determine the gravitational wave luminosity to (post)$^{4}$-Newtonian order
(i.e., order $v^8$ beyond Newtonian) from a particle orbiting around a
Schwarzschild black hole. Our result, valid in the small-mass limit of one
body, gives an important guideline for the study of coalescing compact
binaries. In particular, it provides basic formulas to analytically calculate
detailed waveforms and luminosity, including the tail terms to
(post)$^3$-Newtonian order, which should be reproduced in any other
post-Newtonian calculations.
| [
{
"created": "Thu, 24 Feb 1994 08:00:48 GMT",
"version": "v1"
}
] | 2009-10-09 | [
[
"Sasaki",
"Misao",
""
]
] | We present a method of post-Newtonian expansion to solve the homogeneous Regge-Wheeler equation which describes gravitational waves on the Schwarzschild spacetime. The advantage of our method is that it allows a systematic iterative analysis of the solution. Then we obtain the Regge-Wheeler function which is purely ingoing at the horizon in closed analytic form, with accuracy required to determine the gravitational wave luminosity to (post)$^{4}$-Newtonian order (i.e., order $v^8$ beyond Newtonian) from a particle orbiting around a Schwarzschild black hole. Our result, valid in the small-mass limit of one body, gives an important guideline for the study of coalescing compact binaries. In particular, it provides basic formulas to analytically calculate detailed waveforms and luminosity, including the tail terms to (post)$^3$-Newtonian order, which should be reproduced in any other post-Newtonian calculations. |
1005.4477 | Muhammad Sharif | M. Sharif and Umber Sheikh | Cold Plasma Wave Analysis in Magneto-Rotational Fluids | 22 pages, 18 figures, accepted for publication in Astrophys. Space
Sci | Astrophys.Space Sci.330:317-328,2010 | 10.1007/s10509-010-0407-x | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper is devoted to investigate the cold plasma wave properties. The
analysis has been restricted to the neighborhood of the pair production region
of the Kerr magnetosphere. The Fourier analyzed general relativistic
magnetohydrodynamical equations are dealt under special circumstances and
dispersion relations are obtained. We find the $x$-component of the complex
wave vector numerically. The corresponding components of the propagation
vector, attenuation vector, phase and group velocities are shown in graphs. The
direction and dispersion of waves are investigated.
| [
{
"created": "Tue, 25 May 2010 04:12:12 GMT",
"version": "v1"
}
] | 2010-11-03 | [
[
"Sharif",
"M.",
""
],
[
"Sheikh",
"Umber",
""
]
] | This paper is devoted to investigate the cold plasma wave properties. The analysis has been restricted to the neighborhood of the pair production region of the Kerr magnetosphere. The Fourier analyzed general relativistic magnetohydrodynamical equations are dealt under special circumstances and dispersion relations are obtained. We find the $x$-component of the complex wave vector numerically. The corresponding components of the propagation vector, attenuation vector, phase and group velocities are shown in graphs. The direction and dispersion of waves are investigated. |
1903.10530 | Shahar Hod | Shahar Hod | Upper bound on the gravitational masses of stable spatially regular
charged compact objects | 5 pages | Physical Review D 98, 064014 (2018) | 10.1103/PhysRevD.98.064014 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In a very interesting paper, Andr\'easson has recently proved that the
gravitational mass of a spherically symmetric compact object of radius $R$ and
electric charge $Q$ is bounded from above by the relation
$\sqrt{M}\leq{{\sqrt{R}}\over{3}}+\sqrt{{{R}\over{9}}+{{Q^2}\over{3R}}}$. In
the present paper we prove that, in the dimensionless regime
${{Q}/{M}}<\sqrt{{9/8}}$, a stronger upper bound can be derived on the masses
of physically realistic ({\it stable}) self-gravitating horizonless compact
objects: $M<{{R}\over{3}}+{{2Q^2}\over{3R}}$.
| [
{
"created": "Mon, 25 Mar 2019 18:01:40 GMT",
"version": "v1"
}
] | 2019-04-03 | [
[
"Hod",
"Shahar",
""
]
] | In a very interesting paper, Andr\'easson has recently proved that the gravitational mass of a spherically symmetric compact object of radius $R$ and electric charge $Q$ is bounded from above by the relation $\sqrt{M}\leq{{\sqrt{R}}\over{3}}+\sqrt{{{R}\over{9}}+{{Q^2}\over{3R}}}$. In the present paper we prove that, in the dimensionless regime ${{Q}/{M}}<\sqrt{{9/8}}$, a stronger upper bound can be derived on the masses of physically realistic ({\it stable}) self-gravitating horizonless compact objects: $M<{{R}\over{3}}+{{2Q^2}\over{3R}}$. |
1709.07261 | Vincenzo Vitagliano | Paulo Luz (Minho U. and Lisbon, CENTRA) and Vincenzo Vitagliano
(Lisbon, CENTRA) | Raychaudhuri equation in spacetimes with torsion | 8 pages | Phys.Rev. D96 (2017) no.2, 024021 | 10.1103/PhysRevD.96.024021 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Given a spacetime with nonvanishing torsion, we discuss the equation for the
evolution of the separation vector between infinitesimally close curves in a
congruence. We show that the presence of a torsion field leads, in general, to
tangent and orthogonal effects on the congruence; in particular, the presence
of a completely generic torsion field contributes to a relative acceleration
between test particles. We derive, for the first time in the literature, the
Raychaudhuri equation for a congruence of timelike and null curves in a
spacetime with the most generic torsion field.
| [
{
"created": "Thu, 21 Sep 2017 11:08:41 GMT",
"version": "v1"
}
] | 2017-09-22 | [
[
"Luz",
"Paulo",
"",
"Minho U. and Lisbon, CENTRA"
],
[
"Vitagliano",
"Vincenzo",
"",
"Lisbon, CENTRA"
]
] | Given a spacetime with nonvanishing torsion, we discuss the equation for the evolution of the separation vector between infinitesimally close curves in a congruence. We show that the presence of a torsion field leads, in general, to tangent and orthogonal effects on the congruence; in particular, the presence of a completely generic torsion field contributes to a relative acceleration between test particles. We derive, for the first time in the literature, the Raychaudhuri equation for a congruence of timelike and null curves in a spacetime with the most generic torsion field. |
1609.01735 | Richard Brito | Miguel Duarte, Richard Brito | Asymptotically anti-de Sitter Proca Stars | 8 pages, 6 figures. v2: references added, matches published version | Phys.Rev.D94, 064055 (2016) | 10.1103/PhysRevD.94.064055 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that complex, massive spin-1 fields minimally coupled to Einstein's
gravity with a negative cosmological constant, admit asymptotically anti-de
Sitter self-gravitating solutions. Focusing on 4-dimensional spacetimes, we
start by obtaining analytical solutions in the test-field limit, where the
Proca field equations can be solved in a fixed anti-de Sitter background, and
then find fully non-linear solutions numerically. These solutions are a natural
extension of the recently found asymptotically flat Proca stars and share
similar properties with scalar boson stars. In particular, we show that they
are stable against spherically symmetric linear perturbations for a range of
fundamental frequencies limited by their point of maximum mass. We finish with
an overview of the behavior of Proca stars in $5$ dimensions.
| [
{
"created": "Tue, 6 Sep 2016 20:03:27 GMT",
"version": "v1"
},
{
"created": "Fri, 23 Sep 2016 17:02:48 GMT",
"version": "v2"
}
] | 2016-09-26 | [
[
"Duarte",
"Miguel",
""
],
[
"Brito",
"Richard",
""
]
] | We show that complex, massive spin-1 fields minimally coupled to Einstein's gravity with a negative cosmological constant, admit asymptotically anti-de Sitter self-gravitating solutions. Focusing on 4-dimensional spacetimes, we start by obtaining analytical solutions in the test-field limit, where the Proca field equations can be solved in a fixed anti-de Sitter background, and then find fully non-linear solutions numerically. These solutions are a natural extension of the recently found asymptotically flat Proca stars and share similar properties with scalar boson stars. In particular, we show that they are stable against spherically symmetric linear perturbations for a range of fundamental frequencies limited by their point of maximum mass. We finish with an overview of the behavior of Proca stars in $5$ dimensions. |
gr-qc/0606059 | Leonardo Gualtieri | Valeria Ferrari, Leonardo Gualtieri, Luciano Rezzolla | A hybrid approach to black hole perturbations from extended matter
sources | 12 pages, 4 figures. Phys. Rev. D, in press | Phys.Rev. D73 (2006) 124028 | 10.1103/PhysRevD.73.124028 | null | gr-qc astro-ph | null | We present a new method for the calculation of black hole perturbations
induced by extended sources in which the solution of the nonlinear
hydrodynamics equations is coupled to a perturbative method based on
Regge-Wheeler/Zerilli and Bardeen-Press-Teukolsky equations when these are
solved in the frequency domain. In contrast to alternative methods in the time
domain which may be unstable for rotating black-hole spacetimes, this approach
is expected to be stable as long as an accurate evolution of the matter sources
is possible. Hence, it could be used under generic conditions and also with
sources coming from three-dimensional numerical relativity codes. As an
application of this method we compute the gravitational radiation from an
oscillating high-density torus orbiting around a Schwarzschild black hole and
show that our method is remarkably accurate, capturing both the basic
quadrupolar emission of the torus and the excited emission of the black hole.
| [
{
"created": "Tue, 13 Jun 2006 18:40:29 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Ferrari",
"Valeria",
""
],
[
"Gualtieri",
"Leonardo",
""
],
[
"Rezzolla",
"Luciano",
""
]
] | We present a new method for the calculation of black hole perturbations induced by extended sources in which the solution of the nonlinear hydrodynamics equations is coupled to a perturbative method based on Regge-Wheeler/Zerilli and Bardeen-Press-Teukolsky equations when these are solved in the frequency domain. In contrast to alternative methods in the time domain which may be unstable for rotating black-hole spacetimes, this approach is expected to be stable as long as an accurate evolution of the matter sources is possible. Hence, it could be used under generic conditions and also with sources coming from three-dimensional numerical relativity codes. As an application of this method we compute the gravitational radiation from an oscillating high-density torus orbiting around a Schwarzschild black hole and show that our method is remarkably accurate, capturing both the basic quadrupolar emission of the torus and the excited emission of the black hole. |
2008.12300 | Keisuke Inomata | Keisuke Inomata | Analytic solutions of scalar perturbations induced by scalar
perturbations | 37 pages, 7 figures, v2: version published in JCAP, paragraph
structure changed | null | 10.1088/1475-7516/2021/03/013 | RESCEU-19/20 | gr-qc astro-ph.CO hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study scalar perturbations induced by scalar perturbations through the
non-linear interaction appearing at second order in perturbations. We derive
analytic solutions of the induced scalar perturbations in a perfect fluid. In
particular, we consider the perturbations in a radiation-dominated era and a
matter-dominated era. With the analytic solutions, we also discuss the power
spectra of the induced perturbations.
| [
{
"created": "Thu, 27 Aug 2020 15:01:02 GMT",
"version": "v1"
},
{
"created": "Sun, 14 Mar 2021 14:42:07 GMT",
"version": "v2"
}
] | 2021-03-17 | [
[
"Inomata",
"Keisuke",
""
]
] | We study scalar perturbations induced by scalar perturbations through the non-linear interaction appearing at second order in perturbations. We derive analytic solutions of the induced scalar perturbations in a perfect fluid. In particular, we consider the perturbations in a radiation-dominated era and a matter-dominated era. With the analytic solutions, we also discuss the power spectra of the induced perturbations. |
gr-qc/0301001 | Seiberg | Hong Liu, Gregory Moore and Nathan Seiberg | The Challenging Cosmic Singularity | 11 pages | null | null | null | gr-qc | null | In this talk we discuss the cosmic singularity. We motivate the need to
correct general relativity in the study of singularities, and mention the kind
of corrections provided by string theory. We review how string theory resolves
time-like singularities with two examples. Then, a simple toy model with
lightlike singularities is presented, and studied in classical string theory.
It turns out that classical string theory cannot resolve these singularities,
and therefore better understanding of the full quantum theory is needed. The
implications of this result for the Ekpyrotic/Cyclic Model are discussed. We
end by mentioning the known suggestions for explaining the cosmological
singularity.
| [
{
"created": "Tue, 31 Dec 2002 21:23:49 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Liu",
"Hong",
""
],
[
"Moore",
"Gregory",
""
],
[
"Seiberg",
"Nathan",
""
]
] | In this talk we discuss the cosmic singularity. We motivate the need to correct general relativity in the study of singularities, and mention the kind of corrections provided by string theory. We review how string theory resolves time-like singularities with two examples. Then, a simple toy model with lightlike singularities is presented, and studied in classical string theory. It turns out that classical string theory cannot resolve these singularities, and therefore better understanding of the full quantum theory is needed. The implications of this result for the Ekpyrotic/Cyclic Model are discussed. We end by mentioning the known suggestions for explaining the cosmological singularity. |
gr-qc/0106018 | Roberto Casadio | R. Casadio and B. Harms | Black Hole Decay Rates in Large Extra Dimensions | LaTeX2e with Rinton style, 4 pages, 2 figure EPS files, to appear in
the Proceedings of PASCOS 2001 | null | null | null | gr-qc astro-ph hep-th | null | We study the evaporation of black holes in space-times with extra dimensions
of size L. We show that the luminosity is greatly damped when the horizon
becomes smaller than L and black holes born with an initial size smaller than L
are almost stable. This effect is due to the dependence of both the occupation
number density of Hawking quanta and the grey-body factor of a black hole on
the dimensionality of space.
| [
{
"created": "Wed, 6 Jun 2001 08:01:29 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Casadio",
"R.",
""
],
[
"Harms",
"B.",
""
]
] | We study the evaporation of black holes in space-times with extra dimensions of size L. We show that the luminosity is greatly damped when the horizon becomes smaller than L and black holes born with an initial size smaller than L are almost stable. This effect is due to the dependence of both the occupation number density of Hawking quanta and the grey-body factor of a black hole on the dimensionality of space. |
1812.07923 | Alessandro Nagar | Alessandro Nagar, Francesco Messina, Piero Rettegno, Donato Bini,
Thibault Damour, Andrea Geralico, Sarp Akcay, and Sebastiano Bernuzzi | Nonlinear-in-spin effects in effective-one-body waveform models of
spin-aligned, inspiralling, neutron star binaries | 22 pages, 4 figures, submitted to Phys. Rev. D | Phys. Rev. D 99, 044007 (2019) | 10.1103/PhysRevD.99.044007 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Spinning neutron stars acquire a quadrupole moment due to their own rotation.
This quadratic-in-spin, self-spin effect depends on the equation of state (EOS)
and affects the orbital motion and rate of inspiral of neutron star binaries.
We incorporate the EOS-dependent self-spin (or monopole-quadrupole) terms in
the spin-aligned effective-one-body (EOB) waveform model TEOBResumS at
next-to-next-to-leading (NNLO) order, together with other (bilinear, cubic and
quartic) nonlinear-in-spin effects (at leading order, LO). The structure of the
Hamiltonian of TEOBResumS is such that it already incorporates, in the binary
black hole case, the recently computed quartic-in-spin LO term. Using the
gauge-invariant characterization of the phasing provided by the function
$Q_\omega=\omega^2/\dot{\omega}$ of $\omega=2\pi f$ , where $f$ is the
gravitational wave frequency, we study the EOS dependence of the self-spin
effects and show that: (i) the next-to-leading order (NLO) and NNLO
monopole-quadrupole corrections yield increasingly phase-accelerating effects
compared to the corresponding LO contribution; (ii) the standard TaylorF2
post-Newtonian (PN) treatment of NLO (3PN) EOS-dependent self-spin effects
makes their action stronger than the corresponding EOB description; (iii) the
addition to the standard 3PN TaylorF2 post-Newtonian phasing description of
self-spin tail effects at LO allows one to reconcile the self-spin part of the
TaylorF2 PN phasing with the corresponding TEOBResumS one up to dimensionless
frequencies $M\omega\simeq 0.04-0.06$. By generating the inspiral dynamics
using the post-adiabatic approximation, incorporated in a new implementation of
TEOBResumS, one finds that the computational time needed to obtain a typical
waveform (including all multipoles up to $\ell=8$) from 10 Hz is of the order
of 0.4 sec.
| [
{
"created": "Wed, 19 Dec 2018 13:05:38 GMT",
"version": "v1"
}
] | 2019-02-13 | [
[
"Nagar",
"Alessandro",
""
],
[
"Messina",
"Francesco",
""
],
[
"Rettegno",
"Piero",
""
],
[
"Bini",
"Donato",
""
],
[
"Damour",
"Thibault",
""
],
[
"Geralico",
"Andrea",
""
],
[
"Akcay",
"Sarp",
""
],
[... | Spinning neutron stars acquire a quadrupole moment due to their own rotation. This quadratic-in-spin, self-spin effect depends on the equation of state (EOS) and affects the orbital motion and rate of inspiral of neutron star binaries. We incorporate the EOS-dependent self-spin (or monopole-quadrupole) terms in the spin-aligned effective-one-body (EOB) waveform model TEOBResumS at next-to-next-to-leading (NNLO) order, together with other (bilinear, cubic and quartic) nonlinear-in-spin effects (at leading order, LO). The structure of the Hamiltonian of TEOBResumS is such that it already incorporates, in the binary black hole case, the recently computed quartic-in-spin LO term. Using the gauge-invariant characterization of the phasing provided by the function $Q_\omega=\omega^2/\dot{\omega}$ of $\omega=2\pi f$ , where $f$ is the gravitational wave frequency, we study the EOS dependence of the self-spin effects and show that: (i) the next-to-leading order (NLO) and NNLO monopole-quadrupole corrections yield increasingly phase-accelerating effects compared to the corresponding LO contribution; (ii) the standard TaylorF2 post-Newtonian (PN) treatment of NLO (3PN) EOS-dependent self-spin effects makes their action stronger than the corresponding EOB description; (iii) the addition to the standard 3PN TaylorF2 post-Newtonian phasing description of self-spin tail effects at LO allows one to reconcile the self-spin part of the TaylorF2 PN phasing with the corresponding TEOBResumS one up to dimensionless frequencies $M\omega\simeq 0.04-0.06$. By generating the inspiral dynamics using the post-adiabatic approximation, incorporated in a new implementation of TEOBResumS, one finds that the computational time needed to obtain a typical waveform (including all multipoles up to $\ell=8$) from 10 Hz is of the order of 0.4 sec. |
2010.00281 | Simran Arora | Simran Arora and P.K. Sahoo | Energy conditions in $f(Q,T)$ gravity | Published version in Physica Scripta | Physica Scripta, 95(9) (2020) 095003 | 10.1088/1402-4896/abaddc | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The recently proposed $f(Q, T)$ gravity (Xu et al. Eur. Phys. J. C
\textbf{79} (2019) 708) is an extension of the symmetric teleparallel gravity.
The gravitational action $L$ is given by an arbitrary function $f$ of the
non-metricity $Q$ and the trace of the matter-energy momentum tensor $T$. In
this paper, we examined the essence of some well prompted forms of $f(Q,T)$
gravity models i.e. $f(Q,T)= mQ+bT$ and $f(Q,T)= m Q^{n+1}+b T$ where $m$, $b$,
and $n$ are model parameters. We have used the proposed deceleration parameter,
which predicts both decelerated and accelerated phases of the Universe, with
the transition redshift by recent observations and obtains energy density
($\rho$) and pressure ($p$) to study the various energy conditions for
cosmological models. The equation of state parameter ($\omega\simeq -1$) in the
present model also supports the accelerating behavior of the Universe. In both,
the models, the null, weak, and dominant energy conditions are obeyed with
violating strong energy conditions as per the present accelerated expansion.
| [
{
"created": "Thu, 1 Oct 2020 10:10:21 GMT",
"version": "v1"
}
] | 2020-10-02 | [
[
"Arora",
"Simran",
""
],
[
"Sahoo",
"P. K.",
""
]
] | The recently proposed $f(Q, T)$ gravity (Xu et al. Eur. Phys. J. C \textbf{79} (2019) 708) is an extension of the symmetric teleparallel gravity. The gravitational action $L$ is given by an arbitrary function $f$ of the non-metricity $Q$ and the trace of the matter-energy momentum tensor $T$. In this paper, we examined the essence of some well prompted forms of $f(Q,T)$ gravity models i.e. $f(Q,T)= mQ+bT$ and $f(Q,T)= m Q^{n+1}+b T$ where $m$, $b$, and $n$ are model parameters. We have used the proposed deceleration parameter, which predicts both decelerated and accelerated phases of the Universe, with the transition redshift by recent observations and obtains energy density ($\rho$) and pressure ($p$) to study the various energy conditions for cosmological models. The equation of state parameter ($\omega\simeq -1$) in the present model also supports the accelerating behavior of the Universe. In both, the models, the null, weak, and dominant energy conditions are obeyed with violating strong energy conditions as per the present accelerated expansion. |
gr-qc/0611152 | Jiri Kovar | Jiri Kovar, Zdenek Stuchlik | Forces in Kerr spacetimes with a repulsive cosmological constant | null | Int.J.Mod.Phys.A21:4869-4897,2006 | 10.1142/S0217751X06032435 | null | gr-qc | null | Forces defined in the framework of optical reference geometry are introduced
in the case of stationary and axially symmetric Kerr black-hole and
naked-singularity spacetimes with a repulsive cosmological constant. Properties
of the forces acting on test particles moving along circular orbits in the
equatorial plane are discussed, whereas it is shown where the gravitational
force vanishes and changes its orientation and where the centrifugal force
vanishes and changes its orientation independently of the velocity of test
particles related to the optical geometry; the Coriolis force does not vanish
for the velocity being non-zero. The spacetimes are classified according to the
number of circular orbits where the gravitational and centrifugal forces
vanish.
| [
{
"created": "Thu, 30 Nov 2006 01:07:43 GMT",
"version": "v1"
},
{
"created": "Thu, 30 Nov 2006 23:10:45 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Kovar",
"Jiri",
""
],
[
"Stuchlik",
"Zdenek",
""
]
] | Forces defined in the framework of optical reference geometry are introduced in the case of stationary and axially symmetric Kerr black-hole and naked-singularity spacetimes with a repulsive cosmological constant. Properties of the forces acting on test particles moving along circular orbits in the equatorial plane are discussed, whereas it is shown where the gravitational force vanishes and changes its orientation and where the centrifugal force vanishes and changes its orientation independently of the velocity of test particles related to the optical geometry; the Coriolis force does not vanish for the velocity being non-zero. The spacetimes are classified according to the number of circular orbits where the gravitational and centrifugal forces vanish. |
1106.5296 | Subenoy Chakraborty | Ritabrata Biswas, Nairwita Mazumder, Subenoy Chakraborty | Quantum Tunnelling of non-zero mass particle and evolution of the
horizon for a static black hole | modifications needed | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we study Hawking radiation from a general static black hole due
to tunnelling of particle having nonzero mass. Hawking temperature has been
calculated using both the tunnelling method and the Hamilton-Jacobi method and
the results do no depend on the mass of the particle. Due to complicated form
of the equations involved quantum corrections are evaluated only upto first
order and it is possible to interprete the correction term as loop corrections
of the back reaction effects in the space time. Finally, modified expressions
for entropy and surface gravity has been evaluated and it is found that the
leading order correction term to the entropy is not necessarily logarithmic in
nature.
| [
{
"created": "Mon, 27 Jun 2011 05:34:34 GMT",
"version": "v1"
},
{
"created": "Fri, 28 Sep 2012 17:21:55 GMT",
"version": "v2"
}
] | 2012-10-01 | [
[
"Biswas",
"Ritabrata",
""
],
[
"Mazumder",
"Nairwita",
""
],
[
"Chakraborty",
"Subenoy",
""
]
] | In this work, we study Hawking radiation from a general static black hole due to tunnelling of particle having nonzero mass. Hawking temperature has been calculated using both the tunnelling method and the Hamilton-Jacobi method and the results do no depend on the mass of the particle. Due to complicated form of the equations involved quantum corrections are evaluated only upto first order and it is possible to interprete the correction term as loop corrections of the back reaction effects in the space time. Finally, modified expressions for entropy and surface gravity has been evaluated and it is found that the leading order correction term to the entropy is not necessarily logarithmic in nature. |
1006.0921 | Jeanette E. Nelson | J. E. Nelson and R. F. Picken | Quantum geometry from 2+1 AdS quantum gravity on the torus | 19 pages, 11 figures, revised with more explanations, improved
figures and extra figures. To appear GERG | Gen.Rel.Grav.43:777-795,2011 | 10.1007/s10714-010-1095-0 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Wilson observables for 2+1 quantum gravity with negative cosmological
constant, when the spatial manifold is a torus, exhibit several novel features:
signed area phases relate the observables assigned to homotopic loops, and
their commutators describe loop intersections, with properties that are not yet
fully understood. We describe progress in our study of this bracket, which can
be interpreted as a q-deformed Goldman bracket, and provide a geometrical
interpretation in terms of a quantum version of Pick's formula for the area of
a polygon with integer vertices.
| [
{
"created": "Fri, 4 Jun 2010 15:33:49 GMT",
"version": "v1"
},
{
"created": "Fri, 17 Sep 2010 16:04:55 GMT",
"version": "v2"
}
] | 2011-02-23 | [
[
"Nelson",
"J. E.",
""
],
[
"Picken",
"R. F.",
""
]
] | Wilson observables for 2+1 quantum gravity with negative cosmological constant, when the spatial manifold is a torus, exhibit several novel features: signed area phases relate the observables assigned to homotopic loops, and their commutators describe loop intersections, with properties that are not yet fully understood. We describe progress in our study of this bracket, which can be interpreted as a q-deformed Goldman bracket, and provide a geometrical interpretation in terms of a quantum version of Pick's formula for the area of a polygon with integer vertices. |
gr-qc/0007050 | Teviet Creighton | Teviet Creighton | Tumbleweeds and airborne gravitational noise sources for LIGO | 15 pages, 10 PostScript figures, uses REVTeX4.cls and epsfig.sty | Class.Quant.Grav.25:125011,2008 | 10.1088/0264-9381/25/12/125011 | null | gr-qc | null | Gravitational-wave detectors are sensitive not only to astrophysical
gravitational waves, but also to the fluctuating Newtonian gravitational forces
of moving masses in the ground and air around the detector. This paper studies
the gravitational effects of density perturbations in the atmosphere, and from
massive airborne objects near the detector. These effects were previously
considered by Saulson; in this paper I revisit these phenomena, considering
transient atmospheric shocks, and the effects of sound waves or objects
colliding with the ground or buildings around the test masses. I also consider
temperature perturbations advected past the detector as a source of
gravitational noise. I find that the gravitational noise background is below
the expected noise floor even of advanced interferometric detectors, although
only by an order of magnitude for temperature perturbations carried along
turbulent streamlines. I also find that transient shockwaves in the atmosphere
could potentially produce large spurious signals, with signal-to-noise ratios
in the hundreds in an advanced interferometric detector. These signals could be
vetoed by means of acoustic sensors outside of the buildings. Massive
wind-borne objects such as tumbleweeds could also produce gravitational signals
with signal-to-noise ratios in the hundreds if they collide with the
interferometer buildings, so it may be necessary to build fences preventing
such objects from approaching within about 30m of the test masses.
| [
{
"created": "Wed, 19 Jul 2000 22:22:41 GMT",
"version": "v1"
},
{
"created": "Wed, 19 Jul 2000 23:54:16 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Creighton",
"Teviet",
""
]
] | Gravitational-wave detectors are sensitive not only to astrophysical gravitational waves, but also to the fluctuating Newtonian gravitational forces of moving masses in the ground and air around the detector. This paper studies the gravitational effects of density perturbations in the atmosphere, and from massive airborne objects near the detector. These effects were previously considered by Saulson; in this paper I revisit these phenomena, considering transient atmospheric shocks, and the effects of sound waves or objects colliding with the ground or buildings around the test masses. I also consider temperature perturbations advected past the detector as a source of gravitational noise. I find that the gravitational noise background is below the expected noise floor even of advanced interferometric detectors, although only by an order of magnitude for temperature perturbations carried along turbulent streamlines. I also find that transient shockwaves in the atmosphere could potentially produce large spurious signals, with signal-to-noise ratios in the hundreds in an advanced interferometric detector. These signals could be vetoed by means of acoustic sensors outside of the buildings. Massive wind-borne objects such as tumbleweeds could also produce gravitational signals with signal-to-noise ratios in the hundreds if they collide with the interferometer buildings, so it may be necessary to build fences preventing such objects from approaching within about 30m of the test masses. |
gr-qc/9901024 | Chris Isham | C.J.Isham and J. Butterfield | On the Emergence of Time in Quantum Gravity | To appear in ``The Arguments of Time'', ed. J. Butterfield, Oxford
University Press, 1999 | null | null | Imperial/TP/98--99/23 | gr-qc | null | We discuss from a philosophical perspective the way in which the normal
concept of time might be said to `emerge' in a quantum theory of gravity. After
an introduction, we briefly discuss the notion of emergence, without regard to
time (Section 2). We then introduce the search for a quantum theory of gravity
(Section 3); and review some general interpretative issues about space, time
and matter Section 4). We then discuss the emergence of time in simple quantum
geometrodynamics, and in the Euclidean approach (Section 5). Section 6
concludes.
| [
{
"created": "Fri, 8 Jan 1999 14:02:35 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Isham",
"C. J.",
""
],
[
"Butterfield",
"J.",
""
]
] | We discuss from a philosophical perspective the way in which the normal concept of time might be said to `emerge' in a quantum theory of gravity. After an introduction, we briefly discuss the notion of emergence, without regard to time (Section 2). We then introduce the search for a quantum theory of gravity (Section 3); and review some general interpretative issues about space, time and matter Section 4). We then discuss the emergence of time in simple quantum geometrodynamics, and in the Euclidean approach (Section 5). Section 6 concludes. |
1311.1235 | Hirotada Okawa | Hirotada Okawa, Vitor Cardoso, Paolo Pani | Collapse of self-interacting fields in asymptotically flat spacetimes:
do self-interactions render Minkowski spacetime unstable? | 6 pages, 4 figures. v2: Convergence results added and overall
improvements to the manuscript. Accepted for publication in Phys.Rev.D [Rapid
Communications] | Phys. Rev. D 89, 041502 (2014) | 10.1103/PhysRevD.89.041502 | null | gr-qc hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The nonlinear instability of anti-de Sitter spacetime has recently been
established with the striking result that generic initial data collapses to
form black holes. This outcome suggests that confined matter generically
collapses, and that collapse can only be halted -- at most -- by nonlinear
bound states. Here we provide evidence that such mechanism can operate even in
asymptotically flat spacetimes, by studying the evolution of the
Einstein-Klein-Gordon system for a self-interacting scalar field. We show that
(i) configurations which do not collapse promptly can do so after successive
reflections off the potential barrier, but (ii) that at intermediate amplitudes
and Compton wavelengths, collapse to black holes is replaced by the appearance
of oscillating soliton stars. Finally, (iii) for very small initial amplitudes,
the field disperses away in a manner consistent with power-law tails of massive
fields. Minkowski is stable against gravitational collapse. Our results provide
one further piece to the rich phenomenology of gravitational collapse and show
the important interplay between bound states, blueshift, dissipation and
confinement effects.
| [
{
"created": "Tue, 5 Nov 2013 22:06:32 GMT",
"version": "v1"
},
{
"created": "Fri, 31 Jan 2014 11:59:29 GMT",
"version": "v2"
}
] | 2014-03-05 | [
[
"Okawa",
"Hirotada",
""
],
[
"Cardoso",
"Vitor",
""
],
[
"Pani",
"Paolo",
""
]
] | The nonlinear instability of anti-de Sitter spacetime has recently been established with the striking result that generic initial data collapses to form black holes. This outcome suggests that confined matter generically collapses, and that collapse can only be halted -- at most -- by nonlinear bound states. Here we provide evidence that such mechanism can operate even in asymptotically flat spacetimes, by studying the evolution of the Einstein-Klein-Gordon system for a self-interacting scalar field. We show that (i) configurations which do not collapse promptly can do so after successive reflections off the potential barrier, but (ii) that at intermediate amplitudes and Compton wavelengths, collapse to black holes is replaced by the appearance of oscillating soliton stars. Finally, (iii) for very small initial amplitudes, the field disperses away in a manner consistent with power-law tails of massive fields. Minkowski is stable against gravitational collapse. Our results provide one further piece to the rich phenomenology of gravitational collapse and show the important interplay between bound states, blueshift, dissipation and confinement effects. |
1704.02888 | Jorge Alfaro | Jorge Alfaro and Pablo Gonz\'alez | $\tilde{\delta}$ Gravity, $\tilde{\delta}$ matter and the accelerated
expansion of the Universe | 24 pages,1 figure, latex. arXiv admin note: text overlap with
arXiv:1210.6107 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A gravitational field model based on two symmetric tensors, $g_{\mu \nu}$ and
$\tilde{g}_{\mu \nu}$, is presented. In this model, new matter fields are added
to the original matter fields, motivated by an additional symmetry
($\tilde{\delta}$ symmetry). We call them $\tilde{\delta}$ matter fields. We
find that massive particles do not follow geodesics, while trajectories of
massless particles are null geodesics of an effective metric. Then we study the
Cosmological case, where we get an accelerated expansion of the Universe
without dark energy.
| [
{
"created": "Fri, 7 Apr 2017 17:25:29 GMT",
"version": "v1"
},
{
"created": "Thu, 2 Nov 2017 16:16:22 GMT",
"version": "v2"
}
] | 2017-11-06 | [
[
"Alfaro",
"Jorge",
""
],
[
"González",
"Pablo",
""
]
] | A gravitational field model based on two symmetric tensors, $g_{\mu \nu}$ and $\tilde{g}_{\mu \nu}$, is presented. In this model, new matter fields are added to the original matter fields, motivated by an additional symmetry ($\tilde{\delta}$ symmetry). We call them $\tilde{\delta}$ matter fields. We find that massive particles do not follow geodesics, while trajectories of massless particles are null geodesics of an effective metric. Then we study the Cosmological case, where we get an accelerated expansion of the Universe without dark energy. |
2406.18979 | Joao Magueijo | Raymond Isichei and Joao Magueijo | Attractive voids | null | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We explore the well know mass deficit/surplus phenomenon in General
Relativity to suggest that it could play a part in the dark matter conundrum.
Specifically in collapses and condensations of matter associated with negative
intrinsic curvature of the foliation associated with the asymptotic boundary
conditions, the external (ADM) mass can vastly exceed the integrated local
energy over the internal volume. This can be phrased in terms of a deficit of
volume for a given surface area (with respect to zero curvature). We explore
the phenomenon in the context of generalizations of the Oppenheimer-Snyder
models and other "cut and paste" models, the Lemaitre-Bondi-Tolman metric and
several others. We produce constructions where the internal object is
contracting or expanding, has a life time different from the asymptotic
Universe, as well as a volume different than the escavated volume from the
Universe. These are purely relativistic constructions and they could play a
role in the puzzle of dark matter: attraction without visible or indeed any
matter.
| [
{
"created": "Thu, 27 Jun 2024 08:19:15 GMT",
"version": "v1"
}
] | 2024-06-28 | [
[
"Isichei",
"Raymond",
""
],
[
"Magueijo",
"Joao",
""
]
] | We explore the well know mass deficit/surplus phenomenon in General Relativity to suggest that it could play a part in the dark matter conundrum. Specifically in collapses and condensations of matter associated with negative intrinsic curvature of the foliation associated with the asymptotic boundary conditions, the external (ADM) mass can vastly exceed the integrated local energy over the internal volume. This can be phrased in terms of a deficit of volume for a given surface area (with respect to zero curvature). We explore the phenomenon in the context of generalizations of the Oppenheimer-Snyder models and other "cut and paste" models, the Lemaitre-Bondi-Tolman metric and several others. We produce constructions where the internal object is contracting or expanding, has a life time different from the asymptotic Universe, as well as a volume different than the escavated volume from the Universe. These are purely relativistic constructions and they could play a role in the puzzle of dark matter: attraction without visible or indeed any matter. |
gr-qc/0612102 | Walter Christensen Jr. | Walter J. Christensen Jr | Normal Coordinates Describing Coupled Oscillations in the Gravitational
Field | General Relativity and Gravitation Ref.: Ms. No. GERG-D-06-00077R1
accepted for publication October 06, 2006 | Gen.Rel.Grav.39:105-110,2007 | 10.1007/s10714-006-0360-8 | null | gr-qc | null | The motion of a local source inducing small oscillations in the gravitational
field is investigated and shown to exhibit pure rotational kinetic energy.
Should the net affect of these slow, revolving oscillations cause large-scale
rotations in spacetime it would certainly result in anomalous celestial
accelerations. When this angular rotational frequency of spacetime is applied
to the anomalous acceleration of the Pioneer 10/11 spacecrafts, the correlation
is promising.
| [
{
"created": "Sat, 16 Dec 2006 22:51:45 GMT",
"version": "v1"
},
{
"created": "Tue, 10 Jul 2007 00:54:15 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Christensen",
"Walter J.",
"Jr"
]
] | The motion of a local source inducing small oscillations in the gravitational field is investigated and shown to exhibit pure rotational kinetic energy. Should the net affect of these slow, revolving oscillations cause large-scale rotations in spacetime it would certainly result in anomalous celestial accelerations. When this angular rotational frequency of spacetime is applied to the anomalous acceleration of the Pioneer 10/11 spacecrafts, the correlation is promising. |
gr-qc/0505139 | Jonn Miritzis | John Miritzis | The recollapse problem of closed FRW models in higher-order gravity
theories | 15 pages, 3 figures, submitted to JMP | J.Math.Phys. 46 (2005) 082502 | 10.1063/1.2009648 | null | gr-qc | null | We study the closed universe recollapse conjecture for positively curved FRW
models with a perfect fluid matter source and a scalar field which arises in
the conformal frame of the $R+\alpha R^{2}$ theory. By including ordinary
matter, we extend the analysis of a previous work. We analyze the structure of
the resulted four-dimensional dynamical system with the methods of the center
manifold theory and the normal form theory. It is shown that an initially
expanding closed FRW universe, starting close to the Minkowski spacetime,
cannot avoid recollapse. We discuss the posibility that potentials with a
positive minimum may prevent the recollapse of closed universes.
| [
{
"created": "Fri, 27 May 2005 08:21:41 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Miritzis",
"John",
""
]
] | We study the closed universe recollapse conjecture for positively curved FRW models with a perfect fluid matter source and a scalar field which arises in the conformal frame of the $R+\alpha R^{2}$ theory. By including ordinary matter, we extend the analysis of a previous work. We analyze the structure of the resulted four-dimensional dynamical system with the methods of the center manifold theory and the normal form theory. It is shown that an initially expanding closed FRW universe, starting close to the Minkowski spacetime, cannot avoid recollapse. We discuss the posibility that potentials with a positive minimum may prevent the recollapse of closed universes. |
gr-qc/0505131 | Sebastian Ng | S. Ng | Production of scalar particles in expanding spacetime | 8 pages, 3 figures. (Corrected topographic errors.) | null | null | null | gr-qc | null | In this paper, we investigate cosmological particle production using quantum
field theory (QFT). We will consider how production of scalar particles can
occur in an expanding universe. By introducing a time-dependent energy
parameter representing the time evolution of the universe, the initial vacuum
state will be excited. Consequently, creation of particles is present. Here,
our focus is mainly creation of minimally coupled scalar particles in Minkowski
spacetime.
| [
{
"created": "Thu, 26 May 2005 17:59:18 GMT",
"version": "v1"
},
{
"created": "Tue, 7 Jun 2005 16:47:06 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Ng",
"S.",
""
]
] | In this paper, we investigate cosmological particle production using quantum field theory (QFT). We will consider how production of scalar particles can occur in an expanding universe. By introducing a time-dependent energy parameter representing the time evolution of the universe, the initial vacuum state will be excited. Consequently, creation of particles is present. Here, our focus is mainly creation of minimally coupled scalar particles in Minkowski spacetime. |
0811.3794 | Xiaoning Wu | Xiaoning Wu and Shan Bai | On Uniqueness of Kerr Space-time near null infinity | 15pages | Phys.Rev.D78:124009,2008 | 10.1103/PhysRevD.78.124009 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We re-express the Kerr metric in standard Bondi-Saches' coordinate near null
infinity ${\cal I}^+$. Using the uniqueness result of characteristic initial
value problem, we prove the Kerr metric is the only asymptotic flat,
stationary, axial symmetric, Type-D solution of vacuum Einstein equation. The
Taylor series of Kerr space-time is expressed in terms of B-S coordinates and
the N-P constants have been calculated.
| [
{
"created": "Mon, 24 Nov 2008 02:44:21 GMT",
"version": "v1"
}
] | 2008-12-30 | [
[
"Wu",
"Xiaoning",
""
],
[
"Bai",
"Shan",
""
]
] | We re-express the Kerr metric in standard Bondi-Saches' coordinate near null infinity ${\cal I}^+$. Using the uniqueness result of characteristic initial value problem, we prove the Kerr metric is the only asymptotic flat, stationary, axial symmetric, Type-D solution of vacuum Einstein equation. The Taylor series of Kerr space-time is expressed in terms of B-S coordinates and the N-P constants have been calculated. |
1409.5119 | Hossein Mohseni Sadjadi | H. Mohseni Sadjadi and Parviz Goodarzi | Temperature in warm inflation in non minimal kinetic coupling model | 18 pages, major revision, accepted by the European Physical Journal C | Eur. Phys. J. C (2015) 75: 513 | 10.1140/epjc/s10052-015-3745-6 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Warm inflation in the non minimal derivative coupling model with a general
dissipation coefficient is considered. We investigate conditions for the
existence of the slow roll approximation and study cosmological perturbations.
The spectral index, and the power spectrum are calculated and the temperature
of the universe at the end of the slow roll warm inflation is obtained.
| [
{
"created": "Wed, 17 Sep 2014 17:34:30 GMT",
"version": "v1"
},
{
"created": "Tue, 20 Oct 2015 15:47:03 GMT",
"version": "v2"
}
] | 2017-03-08 | [
[
"Sadjadi",
"H. Mohseni",
""
],
[
"Goodarzi",
"Parviz",
""
]
] | Warm inflation in the non minimal derivative coupling model with a general dissipation coefficient is considered. We investigate conditions for the existence of the slow roll approximation and study cosmological perturbations. The spectral index, and the power spectrum are calculated and the temperature of the universe at the end of the slow roll warm inflation is obtained. |
gr-qc/0209029 | Stefan Hollands | Stefan Hollands and Robert M. Wald | On the Renormalization Group in Curved Spacetime | Latex, 44pp, no figures | Commun.Math.Phys. 237 (2003) 123-160 | 10.1007/s00220-003-0837-1 | null | gr-qc hep-th math-ph math.MP | null | We define the renormalization group flow for a renormalizable interacting
quantum field in curved spacetime via its behavior under scaling of the
spacetime metric, $\g \to \lambda^2 \g$. We consider explicitly the case of a
scalar field, $\phi$, with a self-interaction of the form $\kappa \phi^4$,
although our results should generalize straightforwardly to other
renormalizable theories. We construct the interacting field--as well as its
Wick powers and their time-ordered-products--as formal power series in the
algebra generated by the Wick powers and time-ordered-products of the free
field, and we determine the changes in the interacting field observables
resulting from changes in the renormalization prescription. Our main result is
the proof that, for any fixed renormalization prescription, the interacting
field algebra for the spacetime $(M, \lambda^2 \g)$ with coupling parameters
$p$ is isomorphic to the interacting field algebra for the spacetime $(M, \g)$
but with different values, $p(\lambda)$, of the coupling parameters. The map $p
\to p(\lambda)$ yields the renormalization group flow. The notion of essential
and inessential coupling parameters is defined, and we define the notion of a
fixed point as a point, $p$, in the parameter space for which there is no
change in essential parameters under renormalization group flow.
| [
{
"created": "Mon, 9 Sep 2002 15:53:57 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Hollands",
"Stefan",
""
],
[
"Wald",
"Robert M.",
""
]
] | We define the renormalization group flow for a renormalizable interacting quantum field in curved spacetime via its behavior under scaling of the spacetime metric, $\g \to \lambda^2 \g$. We consider explicitly the case of a scalar field, $\phi$, with a self-interaction of the form $\kappa \phi^4$, although our results should generalize straightforwardly to other renormalizable theories. We construct the interacting field--as well as its Wick powers and their time-ordered-products--as formal power series in the algebra generated by the Wick powers and time-ordered-products of the free field, and we determine the changes in the interacting field observables resulting from changes in the renormalization prescription. Our main result is the proof that, for any fixed renormalization prescription, the interacting field algebra for the spacetime $(M, \lambda^2 \g)$ with coupling parameters $p$ is isomorphic to the interacting field algebra for the spacetime $(M, \g)$ but with different values, $p(\lambda)$, of the coupling parameters. The map $p \to p(\lambda)$ yields the renormalization group flow. The notion of essential and inessential coupling parameters is defined, and we define the notion of a fixed point as a point, $p$, in the parameter space for which there is no change in essential parameters under renormalization group flow. |
1802.09628 | Massimo Tinto | Massimo Tinto | Gravitational Wave Searches with Pulsar Timing Arrays. I: Cancellation
of Clock and Ephemeris Noises | Article submitted to Physical Review D. It is 26 pages long and
includes 2 figures | Phys. Rev. D 97, 084047 (2018) | 10.1103/PhysRevD.97.084047 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose a data processing technique to cancel monopole and dipole noise
sources (such as clock and ephemeris noises respectively) in pulsar timing
array searches for gravitational radiation. These noises are the dominant
sources of correlated timing fluctuations in the lower-part ($ \approx 10^{-9}
- 10^{-8}$ Hz) of the gravitational wave band accessible by pulsar timing
experiments. After deriving the expressions that reconstruct these noises from
the timing data, we estimate the gravitational wave sensitivity of our proposed
processing technique to single-source signals to be at least one order of
magnitude higher than that achievable by directly processing the timing data
from an equal-size array. Since arrays can generate pairs of clock and
ephemeris-free timing combinations that are no longer affected by correlated
noises, we implement with them the cross-correlation statistic to search for an
isotropic stochastic gravitational wave background. We find the resulting
optimal signal-to-noise ratio to be more than one order of magnitude larger
than that obtainable by correlating pairs of timing data from arrays of equal
size.
| [
{
"created": "Mon, 26 Feb 2018 22:11:33 GMT",
"version": "v1"
}
] | 2018-05-02 | [
[
"Tinto",
"Massimo",
""
]
] | We propose a data processing technique to cancel monopole and dipole noise sources (such as clock and ephemeris noises respectively) in pulsar timing array searches for gravitational radiation. These noises are the dominant sources of correlated timing fluctuations in the lower-part ($ \approx 10^{-9} - 10^{-8}$ Hz) of the gravitational wave band accessible by pulsar timing experiments. After deriving the expressions that reconstruct these noises from the timing data, we estimate the gravitational wave sensitivity of our proposed processing technique to single-source signals to be at least one order of magnitude higher than that achievable by directly processing the timing data from an equal-size array. Since arrays can generate pairs of clock and ephemeris-free timing combinations that are no longer affected by correlated noises, we implement with them the cross-correlation statistic to search for an isotropic stochastic gravitational wave background. We find the resulting optimal signal-to-noise ratio to be more than one order of magnitude larger than that obtainable by correlating pairs of timing data from arrays of equal size. |
gr-qc/9605060 | Jonathan Wilson | C J S Clarke, J A Vickers and J P Wilson (Department of Mathematics,
University of Southampton, Southampton, UK.) | Generalised Functions and Distributional Curvature of Cosmic Strings | 11 pages, plain TeX | Class.Quant.Grav. 13 (1996) 2485-2498 | 10.1088/0264-9381/13/9/013 | null | gr-qc | null | A new method is presented for assigning distributional curvature, in an
invariant manner, to a space-time of low differentiability, using the
techniques of Colombeau's `new generalised functions'. The method is applied to
show that curvature of a cone is equivalent to a delta function. The same is
true under small enough perturbations.
| [
{
"created": "Tue, 28 May 1996 12:58:46 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Clarke",
"C J S",
"",
"Department of Mathematics,\n University of Southampton, Southampton, UK."
],
[
"Vickers",
"J A",
"",
"Department of Mathematics,\n University of Southampton, Southampton, UK."
],
[
"Wilson",
"J P",
"",
"Department of Mathematics,\n ... | A new method is presented for assigning distributional curvature, in an invariant manner, to a space-time of low differentiability, using the techniques of Colombeau's `new generalised functions'. The method is applied to show that curvature of a cone is equivalent to a delta function. The same is true under small enough perturbations. |
1607.06389 | Diego S\'aez-G\'omez | Jose Beltran Jimenez, Diego Rubiera-Garcia, Diego Saez-Gomez and
Vincenzo Salzano | Cosmological future singularities in interacting dark energy models | 12 pages, 3 figures, title changed, analysis extended, to be
published in PRD | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The existence of interactions between dark matter and dark energy has been
widely studied, since they can fit well the observational data and may provide
new physics through such an interaction. In this work we analyze these models
and investigate their potential relation with future cosmological
singularities. We find that every future singularity found in the literature
can be mapped into a singularity of the interaction term, that we call
$Q$-singularity, where the energy flow between the dark components diverges.
Furthermore, this framework allows to identify a new type of future singularity
induced by the divergence of the first derivative of the dark energy equation
of state parameter.
| [
{
"created": "Thu, 21 Jul 2016 16:53:18 GMT",
"version": "v1"
},
{
"created": "Mon, 5 Dec 2016 10:18:42 GMT",
"version": "v2"
}
] | 2016-12-06 | [
[
"Jimenez",
"Jose Beltran",
""
],
[
"Rubiera-Garcia",
"Diego",
""
],
[
"Saez-Gomez",
"Diego",
""
],
[
"Salzano",
"Vincenzo",
""
]
] | The existence of interactions between dark matter and dark energy has been widely studied, since they can fit well the observational data and may provide new physics through such an interaction. In this work we analyze these models and investigate their potential relation with future cosmological singularities. We find that every future singularity found in the literature can be mapped into a singularity of the interaction term, that we call $Q$-singularity, where the energy flow between the dark components diverges. Furthermore, this framework allows to identify a new type of future singularity induced by the divergence of the first derivative of the dark energy equation of state parameter. |
gr-qc/0111025 | J. Alberto Lobo | J. Alberto Lobo | Hollow sphere, a flexible multimode Gravitational Wave antenna | 6 pages, 2 figures, LaTeX2e, requires CQG style files. To appear in
the Proceedings of the Amaldi-4 Conference, held at Perth (Australia) in july
2001 | Class.Quant.Grav. 19 (2002) 2029-2034 | 10.1088/0264-9381/19/7/409 | null | gr-qc | null | Hollow spheres have the same theoretical capabilities as the usual solid
ones, since they share identical symmetries. The hollow sphere is however more
flexible, as thickness is an additional parameter one can vary to approach
given specifications. I will briefly discuss the more relevant properties of
the hollow sphere as a GW detector (frequencies, cross sections), and suggest
some scenarios where it can generate significant astrophysical information.
| [
{
"created": "Thu, 8 Nov 2001 15:33:50 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Lobo",
"J. Alberto",
""
]
] | Hollow spheres have the same theoretical capabilities as the usual solid ones, since they share identical symmetries. The hollow sphere is however more flexible, as thickness is an additional parameter one can vary to approach given specifications. I will briefly discuss the more relevant properties of the hollow sphere as a GW detector (frequencies, cross sections), and suggest some scenarios where it can generate significant astrophysical information. |
1108.4367 | Richard Woodard | P. J. Mora (University of Florida), N. C. Tsamis (University of Crete)
and R. P. Woodard (University of Florida) | Generalizing the ADM Computation to Quantum Field Theory | 42 pages, 8 figures, 1 table, uses LaTeX2e | null | 10.1088/0264-9381/29/2/025001 | UFIFT-QG-11-07 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The absence of recognizable, low energy quantum gravitational effects
requires that some asymptotic series expansion be wonderfully accurate, but the
correct expansion might involve logarithms or fractional powers of Newton's
constant. That would explain why conventional perturbation theory shows
uncontrollable ultraviolet divergences. We explore this possibility in the
context of the mass of a charged, gravitating scalar. The classical limit of
this system was solved exactly in 1960 by Arnowitt, Deser and Misner, and their
solution does exhibit nonanalytic dependence on Newton's constant. We derive an
exact functional integral representation for the mass of the quantum field
theoretic system, and then develop an alternate expansion for it based on a
correct implementation of the method of stationary phase. The new expansion
entails adding an infinite class of new diagrams to each order and subtracting
them from higher orders. The zeroth order term of the new expansion has the
physical interpretation of a first quantized Klein-Gordon scalar which forms a
bound state in the gravitational and electromagnetic potentials sourced by its
own probability current. We show that such bound states exist and we obtain
numerical results for their masses.
| [
{
"created": "Mon, 22 Aug 2011 16:14:54 GMT",
"version": "v1"
}
] | 2015-05-30 | [
[
"Mora",
"P. J.",
"",
"University of Florida"
],
[
"Tsamis",
"N. C.",
"",
"University of Crete"
],
[
"Woodard",
"R. P.",
"",
"University of Florida"
]
] | The absence of recognizable, low energy quantum gravitational effects requires that some asymptotic series expansion be wonderfully accurate, but the correct expansion might involve logarithms or fractional powers of Newton's constant. That would explain why conventional perturbation theory shows uncontrollable ultraviolet divergences. We explore this possibility in the context of the mass of a charged, gravitating scalar. The classical limit of this system was solved exactly in 1960 by Arnowitt, Deser and Misner, and their solution does exhibit nonanalytic dependence on Newton's constant. We derive an exact functional integral representation for the mass of the quantum field theoretic system, and then develop an alternate expansion for it based on a correct implementation of the method of stationary phase. The new expansion entails adding an infinite class of new diagrams to each order and subtracting them from higher orders. The zeroth order term of the new expansion has the physical interpretation of a first quantized Klein-Gordon scalar which forms a bound state in the gravitational and electromagnetic potentials sourced by its own probability current. We show that such bound states exist and we obtain numerical results for their masses. |
2110.13070 | Bayram Tekin | Aydin Tavlayan and Bayram Tekin | Spherical timelike orbits around Kerr black holes | 13 pages, 21 figures | null | 10.1103/PhysRevD.104.124059 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the order ten polynomial equation satisfied by the radius of the
spherical timelike orbits for a massive particle with a generic energy around a
Kerr black hole. Even though the radii of the prograde and retrograde orbits at
the equatorial or polar plane for particles with zero or unit energy have a
monotonic dependence on the rotation parameter of the black hole, we show that
there is a critical inclination angle above which the retrograde orbits have a
nonmonotonic dependency on the rotation of the black hole. Thus the capture
cross-section of these retrograde orbits decrease with increasing black hole
spin. Hence their efficiency to reduce the black hole's spin is decreased. We
also provide an equation for the critical inclination angle that shows exactly
at which point the nonmonotonicity starts. In addition, we employ the
Lagrange-B\"{u}rmann method to find approximate analytic solutions from the
known exact solutions.
| [
{
"created": "Mon, 25 Oct 2021 16:07:25 GMT",
"version": "v1"
}
] | 2022-01-05 | [
[
"Tavlayan",
"Aydin",
""
],
[
"Tekin",
"Bayram",
""
]
] | We study the order ten polynomial equation satisfied by the radius of the spherical timelike orbits for a massive particle with a generic energy around a Kerr black hole. Even though the radii of the prograde and retrograde orbits at the equatorial or polar plane for particles with zero or unit energy have a monotonic dependence on the rotation parameter of the black hole, we show that there is a critical inclination angle above which the retrograde orbits have a nonmonotonic dependency on the rotation of the black hole. Thus the capture cross-section of these retrograde orbits decrease with increasing black hole spin. Hence their efficiency to reduce the black hole's spin is decreased. We also provide an equation for the critical inclination angle that shows exactly at which point the nonmonotonicity starts. In addition, we employ the Lagrange-B\"{u}rmann method to find approximate analytic solutions from the known exact solutions. |
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