id stringlengths 9 13 | submitter stringlengths 1 64 ⌀ | authors stringlengths 5 22.9k | title stringlengths 4 245 | comments stringlengths 1 548 ⌀ | journal-ref stringlengths 4 362 ⌀ | doi stringlengths 12 82 ⌀ | report-no stringlengths 2 281 ⌀ | categories stringclasses 793 values | license stringclasses 9 values | orig_abstract stringlengths 24 1.95k | versions listlengths 1 30 | update_date stringlengths 10 10 | authors_parsed listlengths 1 1.74k | abstract stringlengths 21 1.95k |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
2401.12054 | Pujian Mao | Pujian Mao and Weicheng Zhao | Twisting asymptotic symmetries and algebraically special vacuum
solutions | v3: more details and discussions on the twisting charge presented,
refs. added | JHEP 03 (2024) 166 | 10.1007/JHEP03(2024)166 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | In this paper, we study asymptotic symmetries and algebraically special exact
solutions in the Newman-Penrose formalism. Removing the hypersurface orthogonal
condition in the well studied Newman-Unti gauge, we obtain a generic asymptotic
solution space which includes all possible origins of propagating degree of
freedom. The asymptotic symmetry of the generalized system extends the Weyl-BMS
symmetry by two independent local Lorentz transformations with non-trivial
boundary charges, which reveals new boundary degrees of freedom. The
generalized Newman-Unti gauge includes algebraically special condition in its
most convenient form. Remarkably, the generic solutions satisfying the
algebraically special condition truncate in the inverse power of radial
expansions and the non-radial Newman-Penrose equations are explicitly solved at
any order. Hence, we provide the most general algebraically special solution
space and the derivation is self-contained in the Newman-Penrose formalism. The
asymptotic symmetry with respect to the algebraically special condition is the
standard Weyl-BMS symmetry and the symmetry parameters consist only the
integration constant order. We present the Kerr solution and Taub-NUT solution
in the generalized Newman-Unti gauge in a simple form.
| [
{
"created": "Mon, 22 Jan 2024 15:46:40 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Jan 2024 15:59:05 GMT",
"version": "v2"
},
{
"created": "Fri, 29 Mar 2024 13:36:31 GMT",
"version": "v3"
}
] | 2024-04-01 | [
[
"Mao",
"Pujian",
""
],
[
"Zhao",
"Weicheng",
""
]
] | In this paper, we study asymptotic symmetries and algebraically special exact solutions in the Newman-Penrose formalism. Removing the hypersurface orthogonal condition in the well studied Newman-Unti gauge, we obtain a generic asymptotic solution space which includes all possible origins of propagating degree of freedom. The asymptotic symmetry of the generalized system extends the Weyl-BMS symmetry by two independent local Lorentz transformations with non-trivial boundary charges, which reveals new boundary degrees of freedom. The generalized Newman-Unti gauge includes algebraically special condition in its most convenient form. Remarkably, the generic solutions satisfying the algebraically special condition truncate in the inverse power of radial expansions and the non-radial Newman-Penrose equations are explicitly solved at any order. Hence, we provide the most general algebraically special solution space and the derivation is self-contained in the Newman-Penrose formalism. The asymptotic symmetry with respect to the algebraically special condition is the standard Weyl-BMS symmetry and the symmetry parameters consist only the integration constant order. We present the Kerr solution and Taub-NUT solution in the generalized Newman-Unti gauge in a simple form. |
2311.04201 | Jose Beltr\'an Jim\'enez | D\'ebora Aguiar Gomes, Jose Beltr\'an Jim\'enez, Alejandro Jim\'enez
Cano and Tomi S. Koivisto | Pathological Character of Modifications to Coincident General
Relativity: Cosmological Strong Coupling and Ghosts in $f(\Q)$ Theories | 5 pages. V2: Some clarifications added. Version accepted for
publication | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The intrinsic presence of ghosts in the symmetric teleparallel framework is
elucidated. We illustrate our general arguments in $f(\mathbb{Q})$ theories by
studying perturbations in the three inequivalent spatially flat cosmologies.
Two of these branches exhibit reduced linear spectra, signalling they are
infinitely strongly coupled. For the remaining branch we unveil the presence of
seven gravitational degrees of freedom and show that at least one of them is a
ghost. Our results rule out $f(\mathbb{Q})$ cosmologies and clarify the number
of propagating degrees of freedom in these theories.
| [
{
"created": "Tue, 7 Nov 2023 18:40:47 GMT",
"version": "v1"
},
{
"created": "Wed, 13 Mar 2024 18:21:23 GMT",
"version": "v2"
}
] | 2024-03-15 | [
[
"Gomes",
"Débora Aguiar",
""
],
[
"Jiménez",
"Jose Beltrán",
""
],
[
"Cano",
"Alejandro Jiménez",
""
],
[
"Koivisto",
"Tomi S.",
""
]
] | The intrinsic presence of ghosts in the symmetric teleparallel framework is elucidated. We illustrate our general arguments in $f(\mathbb{Q})$ theories by studying perturbations in the three inequivalent spatially flat cosmologies. Two of these branches exhibit reduced linear spectra, signalling they are infinitely strongly coupled. For the remaining branch we unveil the presence of seven gravitational degrees of freedom and show that at least one of them is a ghost. Our results rule out $f(\mathbb{Q})$ cosmologies and clarify the number of propagating degrees of freedom in these theories. |
1310.3320 | Ryan Lang | Ryan N. Lang | Compact binary systems in scalar-tensor gravity. II. Tensor
gravitational waves to second post-Newtonian order | 44 pages | Phys. Rev. D 89, 084014 (2014) | 10.1103/PhysRevD.89.084014 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive the tensor gravitational waveform generated by a binary of
nonspinning compact objects (black holes or neutron stars) in a general class
of scalar-tensor theories of gravity. The waveform is accurate to second
post-Newtonian order beyond the leading order quadrupole approximation. We use
the direct integration of the relaxed Einstein equations formalism,
appropriately adapted to scalar-tensor theories, along with previous results
for the equations of motion in these theories. The self-gravity of the compact
objects is treated with an approach developed by Eardley. The scalar field
causes deviations from the general relativistic waveform that depend only on a
small number of parameters. Among the effects of the scalar field are new
hereditary terms which depend on the past history of the source. One of these,
a dipole-dipole coupling, produces a zero-frequency "gravitational-wave memory"
equivalent to the Christodoulou memory of general relativity. In the special
case of two black holes, the waveform reduces to the general relativistic
waveform. For a mixed (black hole-neutron star) system, the waveform is
identical to that of Einstein's theory to first post-Newtonian order, with
deviations at higher order depending only on a single parameter. The behavior
in these cases matches that found for the equations of motion.
| [
{
"created": "Sat, 12 Oct 2013 00:55:17 GMT",
"version": "v1"
},
{
"created": "Sat, 12 Apr 2014 01:19:19 GMT",
"version": "v2"
}
] | 2014-04-15 | [
[
"Lang",
"Ryan N.",
""
]
] | We derive the tensor gravitational waveform generated by a binary of nonspinning compact objects (black holes or neutron stars) in a general class of scalar-tensor theories of gravity. The waveform is accurate to second post-Newtonian order beyond the leading order quadrupole approximation. We use the direct integration of the relaxed Einstein equations formalism, appropriately adapted to scalar-tensor theories, along with previous results for the equations of motion in these theories. The self-gravity of the compact objects is treated with an approach developed by Eardley. The scalar field causes deviations from the general relativistic waveform that depend only on a small number of parameters. Among the effects of the scalar field are new hereditary terms which depend on the past history of the source. One of these, a dipole-dipole coupling, produces a zero-frequency "gravitational-wave memory" equivalent to the Christodoulou memory of general relativity. In the special case of two black holes, the waveform reduces to the general relativistic waveform. For a mixed (black hole-neutron star) system, the waveform is identical to that of Einstein's theory to first post-Newtonian order, with deviations at higher order depending only on a single parameter. The behavior in these cases matches that found for the equations of motion. |
1202.0394 | Mariafelicia De Laurentis Dr. | M. De Laurentis, S. Capozziello | Black holes and stellar structures in f(R)-gravity | 29 pages, 4 figures, 2 tables, to appear in the Volume: "Black Holes:
Evolution, Theory and Thermodynamics", Nova Publishers. 2012. arXiv admin
note: substantial text overlap with arXiv:0912.5286, arXiv:1101.0219, and
text overlap with arXiv:gr-qc/9703084 by other authors | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We review black hole solutions and self-gravitating structures in
f(R)-gravity.
| [
{
"created": "Thu, 2 Feb 2012 09:58:20 GMT",
"version": "v1"
},
{
"created": "Fri, 3 Feb 2012 10:13:14 GMT",
"version": "v2"
}
] | 2012-02-06 | [
[
"De Laurentis",
"M.",
""
],
[
"Capozziello",
"S.",
""
]
] | We review black hole solutions and self-gravitating structures in f(R)-gravity. |
2005.04659 | Naqing Xie | Xiaokai He and Naqing Xie | Quasi-local energy and Oppenheimer-Snyder collapse | 10 pages, 1 figure, references added, accepted for publication in
Classical and Quantum Gravity | Class. Quantum Grav. 37 (2020) 185016 | 10.1088/1361-6382/aba31c | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a scenario of the gravitational collapse of the
Oppenheimer-Snyder dust cloud with spatially constant matter density. Given a
closed two-surface within the star, three versions of the quasi-local energy
are investigated. We show that, during the collapse, (i) the Geroch energy of
the surface is nonpositive and increases to zero; (ii) the Hawking energy of
the surface is monotonically increasing and approaches to the Hayward energy of
the initial surface; and (iii) the Hayward energy of the surface is conserved
and remains positive. These results have no restrictions on the topology and
the symmetry of the surface.
| [
{
"created": "Sun, 10 May 2020 13:26:23 GMT",
"version": "v1"
},
{
"created": "Tue, 7 Jul 2020 10:26:27 GMT",
"version": "v2"
}
] | 2020-08-26 | [
[
"He",
"Xiaokai",
""
],
[
"Xie",
"Naqing",
""
]
] | We consider a scenario of the gravitational collapse of the Oppenheimer-Snyder dust cloud with spatially constant matter density. Given a closed two-surface within the star, three versions of the quasi-local energy are investigated. We show that, during the collapse, (i) the Geroch energy of the surface is nonpositive and increases to zero; (ii) the Hawking energy of the surface is monotonically increasing and approaches to the Hayward energy of the initial surface; and (iii) the Hayward energy of the surface is conserved and remains positive. These results have no restrictions on the topology and the symmetry of the surface. |
1802.02263 | Joseph Schindler | J C Schindler, A Aguirre | Algorithms for the explicit computation of Penrose diagrams | 54 pages, 19 figures | Class. Quantum Grav. 35, 105019 (2018) | 10.1088/1361-6382/aabce2 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An algorithm is given for explicitly computing Penrose diagrams for
spacetimes of the form $ds^2 = -f(r)\, dt^2 + f(r)^{-1} \, dr^2 + r^2 \,
d\Omega^2$. The resulting diagram coordinates are shown to extend the metric
continuously and nondegenerately across an arbitrary number of horizons. The
method is extended to include piecewise approximations to dynamically evolving
spacetimes using a standard hypersurface junction procedure. Examples generated
by an implementation of the algorithm are shown for standard and new cases. In
the appendix, this algorithm is compared to existing methods.
| [
{
"created": "Tue, 6 Feb 2018 23:36:12 GMT",
"version": "v1"
}
] | 2021-04-16 | [
[
"Schindler",
"J C",
""
],
[
"Aguirre",
"A",
""
]
] | An algorithm is given for explicitly computing Penrose diagrams for spacetimes of the form $ds^2 = -f(r)\, dt^2 + f(r)^{-1} \, dr^2 + r^2 \, d\Omega^2$. The resulting diagram coordinates are shown to extend the metric continuously and nondegenerately across an arbitrary number of horizons. The method is extended to include piecewise approximations to dynamically evolving spacetimes using a standard hypersurface junction procedure. Examples generated by an implementation of the algorithm are shown for standard and new cases. In the appendix, this algorithm is compared to existing methods. |
2012.07649 | Martin Bojowald | Kallan Berglund, Martin Bojowald, Manuel Diaz, Gianni Sims | Quasiclassical solutions for static quantum black holes | 31 pages, 1 figure; v2: additional discussions of consistency
conditions and asymptotic behavior | Phys. Rev. D 109 (2024) 024006 | 10.1103/PhysRevD.109.024006 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A new form of quasiclassical space-time dynamics for constrained systems
reveals how quantum effects can be derived systematically from canonical
quantization of gravitational systems. These quasiclassical methods lead to
additional fields, representing quantum fluctuations and higher moments, that
are coupled to the classical metric components. The new fields describe
non-adiabatic quantum dynamics and can be interpreted as implicit formulations
of non-local quantum corrections in a field theory. This field-theory aspect is
studied here for the first time, applied to a gravitational system for which a
tractable model is constructed. Static solutions for the relevant fields can be
obtained in almost closed form. They reveal new properties of potential
near-horizon and asymptotic effects in canonical quantum gravity and
demonstrate the overall consistency of the formalism.
| [
{
"created": "Mon, 14 Dec 2020 15:44:12 GMT",
"version": "v1"
},
{
"created": "Mon, 13 Nov 2023 19:18:15 GMT",
"version": "v2"
}
] | 2024-01-04 | [
[
"Berglund",
"Kallan",
""
],
[
"Bojowald",
"Martin",
""
],
[
"Diaz",
"Manuel",
""
],
[
"Sims",
"Gianni",
""
]
] | A new form of quasiclassical space-time dynamics for constrained systems reveals how quantum effects can be derived systematically from canonical quantization of gravitational systems. These quasiclassical methods lead to additional fields, representing quantum fluctuations and higher moments, that are coupled to the classical metric components. The new fields describe non-adiabatic quantum dynamics and can be interpreted as implicit formulations of non-local quantum corrections in a field theory. This field-theory aspect is studied here for the first time, applied to a gravitational system for which a tractable model is constructed. Static solutions for the relevant fields can be obtained in almost closed form. They reveal new properties of potential near-horizon and asymptotic effects in canonical quantum gravity and demonstrate the overall consistency of the formalism. |
1812.02659 | Thomas Schucker | Thomas Schucker | The gauge theoretical underpinnings of general relativity | 12 pages, 3 figures. Contribution to the Heraeus-Seminar "100 Years
of Gauge Theory" organized by Silvia De Bianchi and Claus Kiefer, 30 July - 3
August 2018, Physikzentrum Bad Honnef. To appear in the proceedings "100
Years of Gauge Theory. Past, present and future perspectives" in the series
`Fundamental Theories of Physics' (Springer) | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The gauge theoretical formulation of general relativity is presented. We are
only concerned with local intrinsic geometry, i.e. our space-time is an open
subset of a four-dimensional real vector space. Then the gauge group is the set
of differentiable maps from this open subset into the general linear group or
into the Lorentz group or into its spin cover.
| [
{
"created": "Thu, 6 Dec 2018 16:54:30 GMT",
"version": "v1"
}
] | 2018-12-07 | [
[
"Schucker",
"Thomas",
""
]
] | The gauge theoretical formulation of general relativity is presented. We are only concerned with local intrinsic geometry, i.e. our space-time is an open subset of a four-dimensional real vector space. Then the gauge group is the set of differentiable maps from this open subset into the general linear group or into the Lorentz group or into its spin cover. |
gr-qc/9306027 | Alan Rendall | J. Rauch and A. D. Rendall | Blow-Up of Test Fields Near Cauchy Horizons | 10 pages, Plain TeX, MPA-AR-92-1 | Lett.Math.Phys. 29 (1993) 241-248 | 10.1007/BF00750958 | null | gr-qc | null | The behaviour of test fields near a compact Cauchy horizon is investigated.
It is shown that solutions of nonlinear wave equations on Taub spacetime with
generic initial data cannot be continued smoothly to both extensions of the
spacetime through the Cauchy horizon. This is proved using an energy method.
Similar results are obtained for the spacetimes of Moncrief containing a
compact Cauchy horizon and for more general matter models.
| [
{
"created": "Wed, 23 Jun 1993 07:51:46 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Rauch",
"J.",
""
],
[
"Rendall",
"A. D.",
""
]
] | The behaviour of test fields near a compact Cauchy horizon is investigated. It is shown that solutions of nonlinear wave equations on Taub spacetime with generic initial data cannot be continued smoothly to both extensions of the spacetime through the Cauchy horizon. This is proved using an energy method. Similar results are obtained for the spacetimes of Moncrief containing a compact Cauchy horizon and for more general matter models. |
gr-qc/9707002 | Riccardo Giannitrapani | E.Fabri and R.Giannitrapani | Combinatorial Tools for Regge Calculus | 5 pages, LaTeX, no figures. To appear on the Proceedings of the 12th
Italian Conference on General Relativity and Gravitational Physics | null | null | null | gr-qc | null | In this short note we briefly review some recent mathematical results
relevant to the classical Regge Calculus evolution problem.
| [
{
"created": "Tue, 1 Jul 1997 14:33:47 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Fabri",
"E.",
""
],
[
"Giannitrapani",
"R.",
""
]
] | In this short note we briefly review some recent mathematical results relevant to the classical Regge Calculus evolution problem. |
1803.04306 | F Shojai | H. Khodabakhshi, F. Shojai and A. Shirzad | On the classification of consistent boundary conditions for $
\mathit{f}(\mathit{R})$-Gravity | 21 pages | Eur. Phys. J. C (2018) 78:1003 | 10.1140/epjc/s10052-018-6494-5 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using a completely covariant approach, we discuss the role of boundary
conditions (BCs) and the corresponding Gibbons--Hawking--York (GHY) terms in $
\mathit{f}(\mathit{R}) $-gravity in arbitrary dimensions. We show that $
f(\mathit{R}) $-gravity, as a higher derivative theory, is not described by a
degenerate Lagrangian, in its original form. Hence, without introducing
additional variables, one can not obtain consistent BCs, even by adding the GHY
terms (except for $f(\mathit{R})=R$).
However, following the Ostrogradsky approach, we can introduce a scalar field
in the framework of Brans-Dicke formalism to the system to have consistent BCs
by considering appropriate GHY terms. In addition to the Dirichlet BC, the GHY
terms for both Neumann and two types of mixed BCs are derived. We show the
remarkable result that the $f(\mathit{R})$-gravity is itself compatible with
one type of mixed BCs, in $D$ dimension, i.e. it doesn't require any GHY term.
For each BC, we rewrite the GHY term in terms of Arnowit-Deser-Misner (ADM)
variables.
| [
{
"created": "Mon, 12 Mar 2018 15:20:38 GMT",
"version": "v1"
},
{
"created": "Mon, 19 Mar 2018 07:00:33 GMT",
"version": "v2"
},
{
"created": "Tue, 2 Oct 2018 17:54:58 GMT",
"version": "v3"
}
] | 2019-01-01 | [
[
"Khodabakhshi",
"H.",
""
],
[
"Shojai",
"F.",
""
],
[
"Shirzad",
"A.",
""
]
] | Using a completely covariant approach, we discuss the role of boundary conditions (BCs) and the corresponding Gibbons--Hawking--York (GHY) terms in $ \mathit{f}(\mathit{R}) $-gravity in arbitrary dimensions. We show that $ f(\mathit{R}) $-gravity, as a higher derivative theory, is not described by a degenerate Lagrangian, in its original form. Hence, without introducing additional variables, one can not obtain consistent BCs, even by adding the GHY terms (except for $f(\mathit{R})=R$). However, following the Ostrogradsky approach, we can introduce a scalar field in the framework of Brans-Dicke formalism to the system to have consistent BCs by considering appropriate GHY terms. In addition to the Dirichlet BC, the GHY terms for both Neumann and two types of mixed BCs are derived. We show the remarkable result that the $f(\mathit{R})$-gravity is itself compatible with one type of mixed BCs, in $D$ dimension, i.e. it doesn't require any GHY term. For each BC, we rewrite the GHY term in terms of Arnowit-Deser-Misner (ADM) variables. |
2402.10406 | Yan-Gang Miao | Yang Guo, Hao Xie, Yan-Gang Miao | Signal of phase transition hidden in quasinormal modes of regular AdS
black holes | v1: 14 pages, 8 figures, 2 tables; v2: 15 pages, 9 figures,
clarifications and references added, final version to appear in Physics
Letters B | Phys. Lett. B 855 (2024) 138801 | 10.1016/j.physletb.2024.138801 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss the intrinsic relations between thermodynamic phase transitions
and quasinormal modes in regular AdS black holes, specifically in the Bardeen
and Hayward AdS classes. To this end, we calculate the quasinormal modes of
massless scalar field perturbations around small and large black holes via the
Horowitz-Hubeny method. By investigating the isobaric and isothermal phase
transitions for Bardeen and Hayward AdS black holes in detail, we observe that
a dramatic change of quasinormal modes appears near the phase transition point
of small and large black holes, and that it corresponds to the swallow tail
structure in the plane of Gibbs free energy with respect to pressure. Moreover,
by analyzing the evolution of black holes along the coexistence curve of small
and large black hole phases, we also observe the dramatic change in quasinormal
modes. Such a phenomenon confirms the signal of the phase transition in the
quasinormal mode spectrum, which can be understood as a thermodynamic signal
hidden in the dynamical spectrum.
| [
{
"created": "Fri, 16 Feb 2024 02:15:06 GMT",
"version": "v1"
},
{
"created": "Tue, 11 Jun 2024 07:12:39 GMT",
"version": "v2"
}
] | 2024-06-18 | [
[
"Guo",
"Yang",
""
],
[
"Xie",
"Hao",
""
],
[
"Miao",
"Yan-Gang",
""
]
] | We discuss the intrinsic relations between thermodynamic phase transitions and quasinormal modes in regular AdS black holes, specifically in the Bardeen and Hayward AdS classes. To this end, we calculate the quasinormal modes of massless scalar field perturbations around small and large black holes via the Horowitz-Hubeny method. By investigating the isobaric and isothermal phase transitions for Bardeen and Hayward AdS black holes in detail, we observe that a dramatic change of quasinormal modes appears near the phase transition point of small and large black holes, and that it corresponds to the swallow tail structure in the plane of Gibbs free energy with respect to pressure. Moreover, by analyzing the evolution of black holes along the coexistence curve of small and large black hole phases, we also observe the dramatic change in quasinormal modes. Such a phenomenon confirms the signal of the phase transition in the quasinormal mode spectrum, which can be understood as a thermodynamic signal hidden in the dynamical spectrum. |
2407.07792 | Hugo Roussille | Hugo Roussille, Fran\c{c}ois Larrouturou | Gravitational ringdown in the Minimal Theory of Massive Gravity | 17+10 pages, 2 figures | null | null | null | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by/4.0/ | This work focuses on gravitational perturbations of black holes in the
self-accelerating branch of the Minimal Theory of Massive Gravity (MTMG). This
theory is a healthy extension of GR which displays the feature of massive
tensor modes, without additional polarizations, strong-coupling issues nor
requiring screening mechanisms. We proceed by implementing a newly developed
technique that, instead of considering a second-order Schr\"odinger-like
reformulation of perturbation equations, relies on a first-order formulation
and solves it asymptotically, before numerically deriving the quasi-normal
modes. We find that the black holes of MTMG are stable, and that their
quasi-normal modes smoothly differ from the GR ones, for non-vanishing values
of the graviton mass. This work hence confirms the fact that GR is a smooth
limit of MTMG, and opens the exciting possibility of a clean test, performed
for instance by the LISA detector.
| [
{
"created": "Wed, 10 Jul 2024 16:09:37 GMT",
"version": "v1"
}
] | 2024-07-11 | [
[
"Roussille",
"Hugo",
""
],
[
"Larrouturou",
"François",
""
]
] | This work focuses on gravitational perturbations of black holes in the self-accelerating branch of the Minimal Theory of Massive Gravity (MTMG). This theory is a healthy extension of GR which displays the feature of massive tensor modes, without additional polarizations, strong-coupling issues nor requiring screening mechanisms. We proceed by implementing a newly developed technique that, instead of considering a second-order Schr\"odinger-like reformulation of perturbation equations, relies on a first-order formulation and solves it asymptotically, before numerically deriving the quasi-normal modes. We find that the black holes of MTMG are stable, and that their quasi-normal modes smoothly differ from the GR ones, for non-vanishing values of the graviton mass. This work hence confirms the fact that GR is a smooth limit of MTMG, and opens the exciting possibility of a clean test, performed for instance by the LISA detector. |
0809.4819 | Xin Han H.X | Huarun Li, Yi Ling, Xin Han | Modified (A)dS Schwarzschild black holes in Rainbow spacetime | 11 pages. The version to appear in CQG | Class.Quant.Grav.26:065004,2009 | 10.1088/0264-9381/26/6/065004 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A modified (Anti-)de Sitter Schwarzschild black hole solution is presented in
the framework of rainbow gravity with a cosmological constant. Its
thermodynamical properties are investigated. In general the temperature of
modified black holes is dependent on the energy of probes which take the
measurement. However, a notion of intrinsic temperature can be introduced by
identifying these probes with radiation particles emitted from black holes. It
is interesting to find that the Hawking temperature of this sort of black holes
can be reproduced by employing the extended uncertainty principle and modified
dispersion relations to the ordinary (A)dS Schwarzschild black holes.
| [
{
"created": "Sun, 28 Sep 2008 04:41:14 GMT",
"version": "v1"
},
{
"created": "Mon, 23 Feb 2009 02:45:58 GMT",
"version": "v2"
}
] | 2009-03-27 | [
[
"Li",
"Huarun",
""
],
[
"Ling",
"Yi",
""
],
[
"Han",
"Xin",
""
]
] | A modified (Anti-)de Sitter Schwarzschild black hole solution is presented in the framework of rainbow gravity with a cosmological constant. Its thermodynamical properties are investigated. In general the temperature of modified black holes is dependent on the energy of probes which take the measurement. However, a notion of intrinsic temperature can be introduced by identifying these probes with radiation particles emitted from black holes. It is interesting to find that the Hawking temperature of this sort of black holes can be reproduced by employing the extended uncertainty principle and modified dispersion relations to the ordinary (A)dS Schwarzschild black holes. |
gr-qc/9909025 | Luca Lusanna | Luca Lusanna (Firenze) and Roberto de Pietri (Marseille) | Tetrad Gravity: III) Asymptotic Poincare' Charges, the Physical
Hamiltonian and Void Spacetimes | 140 pages, revtex file | null | null | FI-TH/48/99 | gr-qc astro-ph hep-th | null | A discussion of asymptotic weak and strong Poincare' charges in metric
gravity is given to identify the proper Hamiltonian boundary conditions. The
asymptotic part of the lapse and shift functions is put equal to their
analogues on Minkowski hyperplanes. By adding Dirac's ten extra variables at
spatial infinity, metric gravity is extended to incorporate Dirac's ten extra
first class constraints (the new ten momenta equal to the weak Poincare'
charges) and this allows its deparametrization to parametrized Minkowski
theories restricted to spacelike hyperplanes. The absence of supertranslations
implies: i) boundary conditions identifying the family of
Christodoulou-Klainermann spacetimes; ii) the restriction of foliations to
those (Wigner-Sen-Witten hypersurfaces) corresponding to Wigner's hyperplanes
of Minkowski rest-frame instant form. These results are generalized to tetrad
gravity in the new formulation given in gr-qc/9807072, gr-qc/9807073. The
evolution in the parameter labelling the leaves of the foliation is generated
by the weak ADM energy. Some comments on the quantization in a completely fixed
special 3-orthogonal gauge are made.
| [
{
"created": "Tue, 7 Sep 1999 11:15:23 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Lusanna",
"Luca",
"",
"Firenze"
],
[
"de Pietri",
"Roberto",
"",
"Marseille"
]
] | A discussion of asymptotic weak and strong Poincare' charges in metric gravity is given to identify the proper Hamiltonian boundary conditions. The asymptotic part of the lapse and shift functions is put equal to their analogues on Minkowski hyperplanes. By adding Dirac's ten extra variables at spatial infinity, metric gravity is extended to incorporate Dirac's ten extra first class constraints (the new ten momenta equal to the weak Poincare' charges) and this allows its deparametrization to parametrized Minkowski theories restricted to spacelike hyperplanes. The absence of supertranslations implies: i) boundary conditions identifying the family of Christodoulou-Klainermann spacetimes; ii) the restriction of foliations to those (Wigner-Sen-Witten hypersurfaces) corresponding to Wigner's hyperplanes of Minkowski rest-frame instant form. These results are generalized to tetrad gravity in the new formulation given in gr-qc/9807072, gr-qc/9807073. The evolution in the parameter labelling the leaves of the foliation is generated by the weak ADM energy. Some comments on the quantization in a completely fixed special 3-orthogonal gauge are made. |
0710.2032 | James Lindesay | Beth A. Brown, James Lindesay | Construction of a Penrose Diagram for a Spatially Coherent Evaporating
Black Hole | 12 pages, 3 figures | Class.Quant.Grav.25:105026,2008 | 10.1088/0264-9381/25/10/105026 | null | gr-qc | null | A Penrose diagram is constructed for an example black hole that evaporates at
a steady rate as measured by a distant observer, until the mass vanishes,
yielding a final state Minkowski space-time. Coordinate dependencies of
significant features, such as the horizon and coordinate anomalies, are clearly
demonstrated on the diagram. The large-scale causal structure of the space-time
is briefly discussed.
| [
{
"created": "Wed, 10 Oct 2007 14:52:11 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Brown",
"Beth A.",
""
],
[
"Lindesay",
"James",
""
]
] | A Penrose diagram is constructed for an example black hole that evaporates at a steady rate as measured by a distant observer, until the mass vanishes, yielding a final state Minkowski space-time. Coordinate dependencies of significant features, such as the horizon and coordinate anomalies, are clearly demonstrated on the diagram. The large-scale causal structure of the space-time is briefly discussed. |
1306.1159 | Richard Price | Richard H. Price, Gaurav Khanna, Scott A. Hughes | Black hole binary inspiral and trajectory dominance | 15 pages, 12 figures | null | 10.1103/PhysRevD.88.104004 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational waves emitted during the inspiral, plunge and merger of a black
hole binary carry linear momentum. This results in an astrophysically important
recoil to the final merged black hole, a ``kick'' that can eject it from the
nucleus of a galaxy. In a previous paper we showed that the puzzling partial
cancellation of an early kick by a late antikick, and the dependence of the
cancellation on black hole spin, can be understood from the phenomenology of
the linear momentum waveforms. Here we connect that phenomenology to its
underlying cause, the spin-dependence of the inspiral trajectories. This
insight suggests that the details of plunge can be understood more broadly with
a focus on inspiral trajectories.
| [
{
"created": "Wed, 5 Jun 2013 16:12:13 GMT",
"version": "v1"
}
] | 2015-06-16 | [
[
"Price",
"Richard H.",
""
],
[
"Khanna",
"Gaurav",
""
],
[
"Hughes",
"Scott A.",
""
]
] | Gravitational waves emitted during the inspiral, plunge and merger of a black hole binary carry linear momentum. This results in an astrophysically important recoil to the final merged black hole, a ``kick'' that can eject it from the nucleus of a galaxy. In a previous paper we showed that the puzzling partial cancellation of an early kick by a late antikick, and the dependence of the cancellation on black hole spin, can be understood from the phenomenology of the linear momentum waveforms. Here we connect that phenomenology to its underlying cause, the spin-dependence of the inspiral trajectories. This insight suggests that the details of plunge can be understood more broadly with a focus on inspiral trajectories. |
1809.06740 | Arkady A. Popov | A. Popov, O. Aslan | Scalar self-force on static charge in a long throat | 11 pages, 1 figure. arXiv admin note: text overlap with
arXiv:1111.6286 | International Journal of Modern Physics A, Vol. 30, No. 22,
1550143 (2015) | 10.1142/S0217751X15501432 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compute the self-force on a scalar charge at rest in the spacetime of long
throat. We consider arbitrary values of the mass of the scalar field and the
constant of nonmnimal coupling of the scalar field to the curvature of
spacetime. We also show the coincidence of explicit calculations of self-force
in the limit of large mass of the field with known results.
| [
{
"created": "Mon, 17 Sep 2018 13:31:56 GMT",
"version": "v1"
}
] | 2018-09-19 | [
[
"Popov",
"A.",
""
],
[
"Aslan",
"O.",
""
]
] | We compute the self-force on a scalar charge at rest in the spacetime of long throat. We consider arbitrary values of the mass of the scalar field and the constant of nonmnimal coupling of the scalar field to the curvature of spacetime. We also show the coincidence of explicit calculations of self-force in the limit of large mass of the field with known results. |
gr-qc/9708008 | Petr Hajicek | P. Hajicek, Berne | Spherically symmetric gravitating shell as a reparametrization invariant
system | Some sign errors are corrected and a new result is added: Poisson
brackets between no two independent spacetime coordinates of the shell vanish
at any intersection of two horizons | null | 10.1103/PhysRevD.57.936 | null | gr-qc | null | The subject of this paper are spherically symmetric thin shells made of
barotropic ideal fluid and moving under the influence of their own
gravitational field as well as that of a central black hole; the cosmological
constant is assumed to be zero. The general super-Hamiltonian derived in a
previous paper is rewritten for this spherically symmetric special case. The
dependence of the resulting action on the gravitational variables is
trivialized by a transformation due to Kucha\v{r}. The resulting variational
principle depends only on shell variables, is reparametrization invariant, and
includes both first- and second-class constraints. Several equivalent forms of
the constrained system are written down. Exclusion of the second-class
constraints leads to a super-Hamiltonian which appears to overlap with that by
Ansoldi et al. in a quarter of the phase space. As Kucha\v{r}' variables are
singular at the horizons of both Schwarzschild spacetimes inside and outside
the shell, the dynamics is first well-defined only inside of 16 disjoint
sectors. The 16 sectors are, however, shown to be contained in a single,
connected symplectic manifold and the constraints are extended to this manifold
by continuity. Poisson bracket between no two independent spacetime coordinates
of the shell vanish at any intersection of two horizons.
| [
{
"created": "Tue, 5 Aug 1997 13:55:57 GMT",
"version": "v1"
},
{
"created": "Mon, 18 Aug 1997 13:37:24 GMT",
"version": "v2"
}
] | 2009-10-30 | [
[
"Hajicek",
"P.",
""
],
[
"Berne",
"",
""
]
] | The subject of this paper are spherically symmetric thin shells made of barotropic ideal fluid and moving under the influence of their own gravitational field as well as that of a central black hole; the cosmological constant is assumed to be zero. The general super-Hamiltonian derived in a previous paper is rewritten for this spherically symmetric special case. The dependence of the resulting action on the gravitational variables is trivialized by a transformation due to Kucha\v{r}. The resulting variational principle depends only on shell variables, is reparametrization invariant, and includes both first- and second-class constraints. Several equivalent forms of the constrained system are written down. Exclusion of the second-class constraints leads to a super-Hamiltonian which appears to overlap with that by Ansoldi et al. in a quarter of the phase space. As Kucha\v{r}' variables are singular at the horizons of both Schwarzschild spacetimes inside and outside the shell, the dynamics is first well-defined only inside of 16 disjoint sectors. The 16 sectors are, however, shown to be contained in a single, connected symplectic manifold and the constraints are extended to this manifold by continuity. Poisson bracket between no two independent spacetime coordinates of the shell vanish at any intersection of two horizons. |
1008.1158 | Vladim\'ir Balek | Vladim\'ir Balek and Branislav Novotn\'y | Evolution of a black hole-inhabited brane close to reconnection | 20 pages, 4 figures | Phys.Rev.D83:024013,2011 | 10.1103/PhysRevD.83.024013 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Last moments of a mini black hole escaping from a brane are studied. It is
argued that at the point of reconnection, where the piece of the brane attached
to the black hole separates from the rest, the worldsheet of the brane becomes
isotropic (light-like). The degenerate mode of evolution, with the worldsheet
isotropic everywhere, is investigated. In particular, it is shown that the
brane approaches the reconnection point from below if it reconnects within a
certain limit distance, and from above if it reconnects beyond that distance.
The rate of relaxation to the degenerate mode is established. If the dimension
of the brane is $p$, the nondegeneracy, measured by the determinant of the
relevant part of the induced metric tensor, falls down as (latitudinal
angle)$^{2(p - 1)}$.
| [
{
"created": "Fri, 6 Aug 2010 11:00:10 GMT",
"version": "v1"
},
{
"created": "Mon, 15 Nov 2010 16:38:50 GMT",
"version": "v2"
}
] | 2011-02-01 | [
[
"Balek",
"Vladimír",
""
],
[
"Novotný",
"Branislav",
""
]
] | Last moments of a mini black hole escaping from a brane are studied. It is argued that at the point of reconnection, where the piece of the brane attached to the black hole separates from the rest, the worldsheet of the brane becomes isotropic (light-like). The degenerate mode of evolution, with the worldsheet isotropic everywhere, is investigated. In particular, it is shown that the brane approaches the reconnection point from below if it reconnects within a certain limit distance, and from above if it reconnects beyond that distance. The rate of relaxation to the degenerate mode is established. If the dimension of the brane is $p$, the nondegeneracy, measured by the determinant of the relevant part of the induced metric tensor, falls down as (latitudinal angle)$^{2(p - 1)}$. |
2302.09137 | Ernesto Contreras | Eduardo L\'opez, Pedro Bargue\~no, Ernesto Contreras | GUP corrections to black hole thermodynamics in the extended phase space
approach | null | Int. J. Mod. Phys. D, Vol. 31, No. 16, 2250125 (2022) | 10.1142/S0218271822501255 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we study corrections to black hole temperature and entropy in
the context of the generalized uncertainty principle. In particular, we obtain
corrected asymptotically anti de-Sitter black hole solutions following the
extended phase space scheme in which the cosmological constant is considered as
a thermodynamic pressure satisfying certain equation of state. Among all the
possibilities, we consider that the cosmological pressure satisfies either a
Polytropic or a Chaplygin equation of state. The physical plausibility of the
solutions is studied based on the energy conditions and the associated heat
capacity.
| [
{
"created": "Fri, 17 Feb 2023 21:00:52 GMT",
"version": "v1"
}
] | 2023-02-21 | [
[
"López",
"Eduardo",
""
],
[
"Bargueño",
"Pedro",
""
],
[
"Contreras",
"Ernesto",
""
]
] | In this work, we study corrections to black hole temperature and entropy in the context of the generalized uncertainty principle. In particular, we obtain corrected asymptotically anti de-Sitter black hole solutions following the extended phase space scheme in which the cosmological constant is considered as a thermodynamic pressure satisfying certain equation of state. Among all the possibilities, we consider that the cosmological pressure satisfies either a Polytropic or a Chaplygin equation of state. The physical plausibility of the solutions is studied based on the energy conditions and the associated heat capacity. |
1504.00672 | Yuki Watanabe | Yuki Watanabe (Tokyo U., RESCEU & Gunma Coll. Tech.), Atsushi Naruko
(Tokyo Inst. Tech.), Misao Sasaki (Kyoto U., Yukawa Inst., Kyoto) | Multi-disformal invariance of nonlinear primordial perturbations | 8 pages | null | 10.1209/0295-5075/111/39002 | RESCEU-7-15, YITP-15-23 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study disformal transformations of the metric in the cosmological context.
We first consider the disformal transformation generated by a scalar field
$\phi$ and show that the curvature and tensor perturbations on the uniform
$\phi$ slicing, on which the scalar field is homogeneous, are non-linearly
invariant under the disformal transformation. Then we discuss the
transformation properties of the evolution equations for the curvature and
tensor perturbations at full non-linear order in the context of spatial
gradient expansion as well as at linear order. In particular, we show that the
transformation can be described in two typically different ways: one that
clearly shows the physical invariance and the other that shows an apparent
change of the causal structure. Finally we consider a new type of disformal
transformation in which a multi-component scalar field comes into play, which
we call a "multi-disformal transformation". We show that the curvature and
tensor perturbations are invariant at linear order, and also at non-linear
order provided that the system has reached the adiabatic limit.
| [
{
"created": "Thu, 2 Apr 2015 10:06:16 GMT",
"version": "v1"
}
] | 2015-09-02 | [
[
"Watanabe",
"Yuki",
"",
"Tokyo U., RESCEU & Gunma Coll. Tech."
],
[
"Naruko",
"Atsushi",
"",
"Tokyo Inst. Tech."
],
[
"Sasaki",
"Misao",
"",
"Kyoto U., Yukawa Inst., Kyoto"
]
] | We study disformal transformations of the metric in the cosmological context. We first consider the disformal transformation generated by a scalar field $\phi$ and show that the curvature and tensor perturbations on the uniform $\phi$ slicing, on which the scalar field is homogeneous, are non-linearly invariant under the disformal transformation. Then we discuss the transformation properties of the evolution equations for the curvature and tensor perturbations at full non-linear order in the context of spatial gradient expansion as well as at linear order. In particular, we show that the transformation can be described in two typically different ways: one that clearly shows the physical invariance and the other that shows an apparent change of the causal structure. Finally we consider a new type of disformal transformation in which a multi-component scalar field comes into play, which we call a "multi-disformal transformation". We show that the curvature and tensor perturbations are invariant at linear order, and also at non-linear order provided that the system has reached the adiabatic limit. |
gr-qc/0607004 | Clovis Jacinto de Matos | Clovis Jacinto de Matos | Gravitoelectromagnetism and Dark Energy in Superconductors | 10 pages. Poster presented at "From Quantum to Cosmos - Fundamental
Physics Research in Space" 22-24 May 2006, To Appear in Int. J. Mod. Phys. D | Int.J.Mod.Phys.D16:2599-2606,2008 | 10.1142/S0218271807011292 | null | gr-qc | null | A gravitomagnetic analogue of the London moment in superconductors can
explain the anomalous Cooper pair mass excess reported by Janet Tate.
Ultimately the gravitomagnetic London moment is attributed to the breaking of
the principle of general covariance in superconductors. This naturally implies
non-conservation of classical energy-momentum. Possible relation with the
manifestation of dark energy in superconductors is questioned.
| [
{
"created": "Mon, 3 Jul 2006 12:02:21 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"de Matos",
"Clovis Jacinto",
""
]
] | A gravitomagnetic analogue of the London moment in superconductors can explain the anomalous Cooper pair mass excess reported by Janet Tate. Ultimately the gravitomagnetic London moment is attributed to the breaking of the principle of general covariance in superconductors. This naturally implies non-conservation of classical energy-momentum. Possible relation with the manifestation of dark energy in superconductors is questioned. |
gr-qc/9404026 | null | F. Englert, S. Massar and R. Parentani | Source Vacuum Fluctuations of Black Hole Radiance | 33 pages, ULB-TH 03/94, 5 figures not included, available on request
from F.E. (problem with truncation of long lines) | Class.Quant.Grav.11:2919-2938,1994 | 10.1088/0264-9381/11/12/008 | null | gr-qc hep-th | null | The emergence of Hawking radiation from vacuum fluctuations is analyzed in
conventional field theories and their energy content is defined through the
Aharonov weak value concept. These fluctuations travel in flat space-time and
carry transplanckian energies sharply localized on cisplanckian distances. We
argue that these features cannot accommodate gravitational nonlinearities. We
suggest that the very emission of Hawking photons from tamed vacuum
fluctuations requires the existence of an exploding set of massive fields.
These considerations corroborate some conjectures of Susskind and may prove
relevant for the back-reaction problem and for the unitarity issue.
| [
{
"created": "Wed, 13 Apr 1994 15:02:18 GMT",
"version": "v1"
},
{
"created": "Thu, 14 Apr 1994 13:07:55 GMT",
"version": "v2"
}
] | 2010-04-06 | [
[
"Englert",
"F.",
""
],
[
"Massar",
"S.",
""
],
[
"Parentani",
"R.",
""
]
] | The emergence of Hawking radiation from vacuum fluctuations is analyzed in conventional field theories and their energy content is defined through the Aharonov weak value concept. These fluctuations travel in flat space-time and carry transplanckian energies sharply localized on cisplanckian distances. We argue that these features cannot accommodate gravitational nonlinearities. We suggest that the very emission of Hawking photons from tamed vacuum fluctuations requires the existence of an exploding set of massive fields. These considerations corroborate some conjectures of Susskind and may prove relevant for the back-reaction problem and for the unitarity issue. |
1402.4146 | Michael P\"urrer | Michael P\"urrer | Frequency domain reduced order models for gravitational waves from
aligned-spin compact binaries | 36 pages, 19 figures, version published in CQG | Class. Quantum Grav. 31 195010, 2014 | 10.1088/0264-9381/31/19/195010 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Black-hole binary coalescences are one of the most promising sources for the
first detection of gravitational waves. Fast and accurate theoretical models of
the gravitational radiation emitted from these coalescences are highly
important for the detection and extraction of physical parameters. Spinning
effective-one-body (EOB) models for binaries with aligned spins have been shown
to be highly faithful, but are slow to generate and thus have not yet been used
for parameter estimation studies. I provide a frequency-domain singular value
decomposition (SVD)-based surrogate reduced order model that is thousands of
times faster for typical system masses and has a faithfulness mismatch of
better than $\sim 0.1\%$ with the original SEOBNRv1 model for advanced LIGO
detectors. This model enables parameter estimation studies up to
signal-to-noise ratios (SNRs) of 20 and even up to SNR 50 for total masses
below $50 M_\odot$. This article discusses various choices for approximations
and interpolation over the parameter space that can be made for reduced order
models of spinning compact binaries, provides a detailed discussion of errors
arising in the construction and assesses the fidelity of such models.
| [
{
"created": "Mon, 17 Feb 2014 21:10:55 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Oct 2014 16:23:54 GMT",
"version": "v2"
}
] | 2014-10-17 | [
[
"Pürrer",
"Michael",
""
]
] | Black-hole binary coalescences are one of the most promising sources for the first detection of gravitational waves. Fast and accurate theoretical models of the gravitational radiation emitted from these coalescences are highly important for the detection and extraction of physical parameters. Spinning effective-one-body (EOB) models for binaries with aligned spins have been shown to be highly faithful, but are slow to generate and thus have not yet been used for parameter estimation studies. I provide a frequency-domain singular value decomposition (SVD)-based surrogate reduced order model that is thousands of times faster for typical system masses and has a faithfulness mismatch of better than $\sim 0.1\%$ with the original SEOBNRv1 model for advanced LIGO detectors. This model enables parameter estimation studies up to signal-to-noise ratios (SNRs) of 20 and even up to SNR 50 for total masses below $50 M_\odot$. This article discusses various choices for approximations and interpolation over the parameter space that can be made for reduced order models of spinning compact binaries, provides a detailed discussion of errors arising in the construction and assesses the fidelity of such models. |
2101.00176 | Vinod Bhardwaj Dr. | Anirudh Pradhan, Archana Dixit, Vinod Kumar Bhardwaj | Barrow HDE model for Statefinder diagnostic in FLRW Universe | 16 pages, 8 figures, Paper accepted in Int. J. Mod. Phys. A | Int. J. Mod. Phys. A, Vol. 36, Issue 04, 10 Feb (2021) 2150030 (13
pages) | 10.1142/S0217751X21500305 | null | gr-qc | http://creativecommons.org/licenses/by-nc-nd/4.0/ | We have analyzed the Barrow holographic dark energy (BHDE) in the framework
of the flat FLRW Universe by considering the various estimations of Barrow
exponent $\triangle$. Here we define BHDE, by applying the usual holographic
principle at a cosmological system, for utilizing the Barrow entropy rather
than the standard Bekenstein-Hawking. To understand the recent accelerated
expansion of the universe, considering the Hubble horizon as the IR cut-off.
The cosmological parameters, especially the density parameter ($\Omega_{_D}$),
the equation of the state parameter ($\omega_{_D}$), energy density
($\rho_{_{D}}$) and the deceleration parameter($q$) are studied in this
manuscript and found the satisfactory behaviors. Moreover, we additionally
focus on the two geometric diagnostics, the statefinder $(r,s)$ and $O_{m}(z)$
to discriminant BHDE model from the $\Lambda CDM$ model. Here we determined and
plotted the trajectories of evolution for statefinder $(r, s)$, $(r,q)$ and
$O_{m}(z)$ diagnostic plane to understand the geometrical behavior of the BHDE
model by utilizing Planck 2018 observational information. Finally, we have
explored the new Barrow exponent $\triangle$, which strongly affects the dark
energy equation of state that can lead it to lie in the quintessence regime,
phantom regime, and exhibits the phantom-divide line during the cosmological
evolution.
| [
{
"created": "Fri, 1 Jan 2021 06:09:17 GMT",
"version": "v1"
}
] | 2021-08-02 | [
[
"Pradhan",
"Anirudh",
""
],
[
"Dixit",
"Archana",
""
],
[
"Bhardwaj",
"Vinod Kumar",
""
]
] | We have analyzed the Barrow holographic dark energy (BHDE) in the framework of the flat FLRW Universe by considering the various estimations of Barrow exponent $\triangle$. Here we define BHDE, by applying the usual holographic principle at a cosmological system, for utilizing the Barrow entropy rather than the standard Bekenstein-Hawking. To understand the recent accelerated expansion of the universe, considering the Hubble horizon as the IR cut-off. The cosmological parameters, especially the density parameter ($\Omega_{_D}$), the equation of the state parameter ($\omega_{_D}$), energy density ($\rho_{_{D}}$) and the deceleration parameter($q$) are studied in this manuscript and found the satisfactory behaviors. Moreover, we additionally focus on the two geometric diagnostics, the statefinder $(r,s)$ and $O_{m}(z)$ to discriminant BHDE model from the $\Lambda CDM$ model. Here we determined and plotted the trajectories of evolution for statefinder $(r, s)$, $(r,q)$ and $O_{m}(z)$ diagnostic plane to understand the geometrical behavior of the BHDE model by utilizing Planck 2018 observational information. Finally, we have explored the new Barrow exponent $\triangle$, which strongly affects the dark energy equation of state that can lead it to lie in the quintessence regime, phantom regime, and exhibits the phantom-divide line during the cosmological evolution. |
2407.01359 | \'Angel Murcia | Bernardo Araneda and \'Angel J. Murcia | Generalized Siklos space-times | 14 pages. Two appendices | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Motivated by supersymmetry methods in general relativity, we study
four-dimensional Lorentzian space-times with a complex Dirac spinor field
satisfying a Killing-spinor-like equation where the Killing constant is
promoted to a complex function. We call the resulting geometry a generalized
Siklos space-time. After deriving a number of identities for complex spaces, we
specialize to Lorentz signature, where we show that the Killing function must
be real and that the corresponding Dirac spinor is Majorana (as long as the
space-time is not conformally flat), and we obtain the local form of the
metric. We show that the purely gravitational degrees of freedom correspond to
waves, whereas the matter sources generically correspond, via Einstein's field
equations, to a sum of pure radiation and a space-like perfect fluid.
Consequently, we conclude that the physically relevant case is obtained when
the Killing function is homogeneous on the wave surfaces.
| [
{
"created": "Mon, 1 Jul 2024 15:12:49 GMT",
"version": "v1"
}
] | 2024-07-02 | [
[
"Araneda",
"Bernardo",
""
],
[
"Murcia",
"Ángel J.",
""
]
] | Motivated by supersymmetry methods in general relativity, we study four-dimensional Lorentzian space-times with a complex Dirac spinor field satisfying a Killing-spinor-like equation where the Killing constant is promoted to a complex function. We call the resulting geometry a generalized Siklos space-time. After deriving a number of identities for complex spaces, we specialize to Lorentz signature, where we show that the Killing function must be real and that the corresponding Dirac spinor is Majorana (as long as the space-time is not conformally flat), and we obtain the local form of the metric. We show that the purely gravitational degrees of freedom correspond to waves, whereas the matter sources generically correspond, via Einstein's field equations, to a sum of pure radiation and a space-like perfect fluid. Consequently, we conclude that the physically relevant case is obtained when the Killing function is homogeneous on the wave surfaces. |
1405.2098 | Richard Brito | Richard Brito, Vitor Cardoso, Paolo Pani | Superradiant instability of black holes immersed in a magnetic field | 13 pages, 6 figures. v2: references added, matches published version | Phys.Rev.D89:104045,2014 | 10.1103/PhysRevD.89.104045 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Magnetic fields surrounding spinning black holes can confine radiation and
trigger superradiant instabilities. To investigate this effect, we perform the
first fully-consistent linear analysis of the Ernst spacetime, an exact
solution of the Einstein--Maxwell equations describing a black hole immersed in
a uniform magnetic field $B$. In the limit in which the black-hole mass
vanishes, the background reduces to the marginally stable Melvin spacetime. The
presence of an event horizon introduces a small dissipative term, resulting in
a set of long-lived -- or unstable -- modes. We provide a simple interpretation
of the mode spectrum in terms of a small perfect absorber immersed in a
confining box of size $\sim1/B$ and show that rotation triggers a superradiant
instability. By studying scalar perturbations of a magnetized Kerr--Newman
black hole, we are able to confirm and quantify the details of this
instability. The instability time scale can be orders of magnitude shorter than
that associated to massive bosonic fields. The instability extracts angular
momentum from the event horizon, competing against accretion. This implies that
strong magnetic fields set an upper bound on the black-hole spin. Conversely,
observations of highly-spinning massive black holes impose an intrinsic limit
to the strength of the surrounding magnetic field. We discuss the astrophysical
implications of our results and the limitations of the Ernst spacetime to
describe realistic astrophysical configurations.
| [
{
"created": "Thu, 8 May 2014 21:05:01 GMT",
"version": "v1"
},
{
"created": "Tue, 27 May 2014 20:40:02 GMT",
"version": "v2"
}
] | 2014-05-29 | [
[
"Brito",
"Richard",
""
],
[
"Cardoso",
"Vitor",
""
],
[
"Pani",
"Paolo",
""
]
] | Magnetic fields surrounding spinning black holes can confine radiation and trigger superradiant instabilities. To investigate this effect, we perform the first fully-consistent linear analysis of the Ernst spacetime, an exact solution of the Einstein--Maxwell equations describing a black hole immersed in a uniform magnetic field $B$. In the limit in which the black-hole mass vanishes, the background reduces to the marginally stable Melvin spacetime. The presence of an event horizon introduces a small dissipative term, resulting in a set of long-lived -- or unstable -- modes. We provide a simple interpretation of the mode spectrum in terms of a small perfect absorber immersed in a confining box of size $\sim1/B$ and show that rotation triggers a superradiant instability. By studying scalar perturbations of a magnetized Kerr--Newman black hole, we are able to confirm and quantify the details of this instability. The instability time scale can be orders of magnitude shorter than that associated to massive bosonic fields. The instability extracts angular momentum from the event horizon, competing against accretion. This implies that strong magnetic fields set an upper bound on the black-hole spin. Conversely, observations of highly-spinning massive black holes impose an intrinsic limit to the strength of the surrounding magnetic field. We discuss the astrophysical implications of our results and the limitations of the Ernst spacetime to describe realistic astrophysical configurations. |
2006.03939 | Badri Krishnan | Daniel Pook-Kolb, Ofek Birnholtz, Jose Luis Jaramillo, Badri Krishnan
and Erik Schnetter | Horizons in a binary black hole merger I: Geometry and area increase | 20 pages, 14 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recent advances in numerical relativity have revealed how marginally trapped
surfaces behave when black holes merge. It is now known that interesting
topological features emerge during the merger, and marginally trapped surfaces
can have self-intersections. This paper presents the most detailed study yet of
the physical and geometric aspects of this scenario. For the case of a head-on
collision of non-spinning black holes, we study in detail the world tube formed
by the evolution of marginally trapped surfaces. In the first of this two-part
study, we focus on geometrical properties of the dynamical horizons, i.e. the
world tube traced out by the time evolution of marginally outer trapped
surfaces. We show that even the simple case of a head-on collision of
non-spinning black holes contains a rich variety of geometric and topological
properties and is generally more complex than considered previously in the
literature. The dynamical horizons are shown to have mixed signature and are
not future marginally trapped everywhere. We analyze the area increase of the
marginal surfaces along a sequence which connects the two initially disjoint
horizons with the final common horizon. While the area does increase overall
along this sequence, it is not monotonic. We find short durations of anomalous
area change which, given the connection of area with entropy, might have
interesting physical consequences. We investigate the possible reasons for this
effect and show that it is consistent with existing proofs of the area increase
law.
| [
{
"created": "Sat, 6 Jun 2020 18:56:18 GMT",
"version": "v1"
}
] | 2020-06-09 | [
[
"Pook-Kolb",
"Daniel",
""
],
[
"Birnholtz",
"Ofek",
""
],
[
"Jaramillo",
"Jose Luis",
""
],
[
"Krishnan",
"Badri",
""
],
[
"Schnetter",
"Erik",
""
]
] | Recent advances in numerical relativity have revealed how marginally trapped surfaces behave when black holes merge. It is now known that interesting topological features emerge during the merger, and marginally trapped surfaces can have self-intersections. This paper presents the most detailed study yet of the physical and geometric aspects of this scenario. For the case of a head-on collision of non-spinning black holes, we study in detail the world tube formed by the evolution of marginally trapped surfaces. In the first of this two-part study, we focus on geometrical properties of the dynamical horizons, i.e. the world tube traced out by the time evolution of marginally outer trapped surfaces. We show that even the simple case of a head-on collision of non-spinning black holes contains a rich variety of geometric and topological properties and is generally more complex than considered previously in the literature. The dynamical horizons are shown to have mixed signature and are not future marginally trapped everywhere. We analyze the area increase of the marginal surfaces along a sequence which connects the two initially disjoint horizons with the final common horizon. While the area does increase overall along this sequence, it is not monotonic. We find short durations of anomalous area change which, given the connection of area with entropy, might have interesting physical consequences. We investigate the possible reasons for this effect and show that it is consistent with existing proofs of the area increase law. |
gr-qc/0309002 | Anzhong Wang | Yumei Wu, M.F.A. da Silva, N.O. Santos, and Anzhong Wang | Topological Charged Black Holes in High Dimensional Spacetimes and Their
Formation from Gravitational Collapse of a Type II Fluid | 14 figures, to appear in Phys. Rev. D | Phys.Rev.D68:084012,2003 | 10.1103/PhysRevD.68.084012 | null | gr-qc hep-th | null | Topological charged black holes coupled with a cosmological constant in
$R^{2}\times X^{D-2}$ spacetimes are studied, where $X^{D-2}$ is an Einstein
space of the form ${}^{(D-2)}R_{AB} = k(D-3) h_{AB}$. The global structure for
the four-dimensional spacetimes with $k = 0$ is investigated systematically.
The most general solutions that represent a Type $II$ fluid in such a high
dimensional spacetime are found, and showed that topological charged black
holes can be formed from the gravitational collapse of such a fluid. When the
spacetime is (asymptotically) self-similar, the collapse always forms black
holes for $k = 0, -1$, in contrast to the case $k = 1$, where it can form
either balck holes or naked singularities.
| [
{
"created": "Sat, 30 Aug 2003 20:03:18 GMT",
"version": "v1"
}
] | 2009-07-07 | [
[
"Wu",
"Yumei",
""
],
[
"da Silva",
"M. F. A.",
""
],
[
"Santos",
"N. O.",
""
],
[
"Wang",
"Anzhong",
""
]
] | Topological charged black holes coupled with a cosmological constant in $R^{2}\times X^{D-2}$ spacetimes are studied, where $X^{D-2}$ is an Einstein space of the form ${}^{(D-2)}R_{AB} = k(D-3) h_{AB}$. The global structure for the four-dimensional spacetimes with $k = 0$ is investigated systematically. The most general solutions that represent a Type $II$ fluid in such a high dimensional spacetime are found, and showed that topological charged black holes can be formed from the gravitational collapse of such a fluid. When the spacetime is (asymptotically) self-similar, the collapse always forms black holes for $k = 0, -1$, in contrast to the case $k = 1$, where it can form either balck holes or naked singularities. |
2312.16021 | Alexey Golovnev | Alexey Golovnev, A. N. Semenova, V.P. Vandeev | Conformal Transformations and Cosmological Perturbations in New General
Relativity | 17 pages; the final version | Journal of Cosmology and Astroparticle Physics, JCAP04(2024)064 | 10.1088/1475-7516/2024/04/064 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study conformal transformations in the most general parity-preserving
models of the New General Relativity type. Then we apply them to analysis of
cosmological perturbations in the (simplest) spatially flat cosmologies. Strong
coupling issues around Minkowski spacetime are seen for many special cases of
these models. At the same time, the behaviour of the most general
three-parameter case seems to be very robust, presumably always with only the
eight first-class constraints coming from diffeomorphisms. Also the case of the
so-called 1-parameter New GR doesn't show any discontinuity between Minkowski
and the cosmology, though without showing any deviations from GR which would be
observable at this level either.
| [
{
"created": "Tue, 26 Dec 2023 12:21:01 GMT",
"version": "v1"
},
{
"created": "Mon, 15 Jan 2024 16:32:11 GMT",
"version": "v2"
},
{
"created": "Sun, 24 Mar 2024 07:21:50 GMT",
"version": "v3"
}
] | 2024-04-24 | [
[
"Golovnev",
"Alexey",
""
],
[
"Semenova",
"A. N.",
""
],
[
"Vandeev",
"V. P.",
""
]
] | We study conformal transformations in the most general parity-preserving models of the New General Relativity type. Then we apply them to analysis of cosmological perturbations in the (simplest) spatially flat cosmologies. Strong coupling issues around Minkowski spacetime are seen for many special cases of these models. At the same time, the behaviour of the most general three-parameter case seems to be very robust, presumably always with only the eight first-class constraints coming from diffeomorphisms. Also the case of the so-called 1-parameter New GR doesn't show any discontinuity between Minkowski and the cosmology, though without showing any deviations from GR which would be observable at this level either. |
gr-qc/0411048 | Vitor Cardoso | Vitor Cardoso | A note on the resonant frequencies of rapidly rotating black holes | 5 pages, ReVTeX 4 | Phys.Rev. D70 (2004) 127502 | 10.1103/PhysRevD.70.127502 | null | gr-qc astro-ph hep-th | null | I discuss the range of validity of Detweiler's formula for the resonant
frequencies of rapidly rotating Kerr black holes. While his formula is correct
for extremal black holes, it has also been commonly accepted that it describes
very well the resonant frequencies of near extremal black holes, and that
therefore there is a large number of modes clustering on the real axis as the
black hole becomes extremal. I will show that this last statement is not only
incorrect, but that it also does not follow from Detweiler's formula, provided
it is handled with due care. It turns out that only the first n <<
-log{(r_+-r_-)/r_+} modes are well described by that formula, which translates,
for any astrophysical black hole, into one or two modes only. All existing
numerical data gives further support to this claim. I also discuss some
implications of this result for recent investigations on the late-time dynamics
of rapidly rotating black holes.
| [
{
"created": "Tue, 9 Nov 2004 14:31:25 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Cardoso",
"Vitor",
""
]
] | I discuss the range of validity of Detweiler's formula for the resonant frequencies of rapidly rotating Kerr black holes. While his formula is correct for extremal black holes, it has also been commonly accepted that it describes very well the resonant frequencies of near extremal black holes, and that therefore there is a large number of modes clustering on the real axis as the black hole becomes extremal. I will show that this last statement is not only incorrect, but that it also does not follow from Detweiler's formula, provided it is handled with due care. It turns out that only the first n << -log{(r_+-r_-)/r_+} modes are well described by that formula, which translates, for any astrophysical black hole, into one or two modes only. All existing numerical data gives further support to this claim. I also discuss some implications of this result for recent investigations on the late-time dynamics of rapidly rotating black holes. |
gr-qc/0612167 | Sabine Hossenfelder | S. Hossenfelder | Deformed Special Relativity in Position Space | replaced with published version. due to page limits this version is
significantly shorter than the 1st | Phys.Lett.B649:310-316,2007 | 10.1016/j.physletb.2007.04.019 | null | gr-qc hep-th | null | We investigate how deformations of special relativity in momentum space can
be extended to position space in a consistent way, such that the dimensionless
contraction between wave-vector and coordinate-vector remains invariant. By
using a parametrization in terms of an energy dependent speed of light, and an
energy dependent Planck's constant, we are able to formulate simple
requirements that completely determine the active transformations in position
space. These deviate from the standard transformations for large velocities of
the observed object. Some examples are discussed, and it is shown how the
relativistic mass gain of a massive particle is affected. We finally study the
construction of passive Lorentz-transformations.
| [
{
"created": "Tue, 26 Dec 2006 11:47:23 GMT",
"version": "v1"
},
{
"created": "Fri, 25 May 2007 02:28:15 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Hossenfelder",
"S.",
""
]
] | We investigate how deformations of special relativity in momentum space can be extended to position space in a consistent way, such that the dimensionless contraction between wave-vector and coordinate-vector remains invariant. By using a parametrization in terms of an energy dependent speed of light, and an energy dependent Planck's constant, we are able to formulate simple requirements that completely determine the active transformations in position space. These deviate from the standard transformations for large velocities of the observed object. Some examples are discussed, and it is shown how the relativistic mass gain of a massive particle is affected. We finally study the construction of passive Lorentz-transformations. |
1509.08587 | Jung-Jeng Huang | Jung-Jeng Huang | Evaluation of the cosmological constant in inflation with a massive
non-minimal scalar field | null | Advances in High Energy Physics, volume 2015 (2015), Article ID
569789, 7 pages | 10.1155/2015/569789 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In Schroedinger picture we study the possible effects of trans-Planckian
physics on the quantum evolution of massive non-minimally coupled scalar field
in de Sitter space. For the nonlinear Corley-Jacobson type dispersion relations
with quartic or sextic correction, we obtain the time evolution of the vacuum
state wave functional during slow-roll inflation, and calculate explicitly the
corresponding expectation value of vacuum energy density. We find that the
vacuum energy density is finite. For the usual dispersion parameter choice, the
vacuum energy density for quartic correction to the dispersion relation is
larger than for sextic correction, while for some other parameter choices, the
vacuum energy density for quartic correction is smaller than for sextic
correction. We also use the backreaction to constrain the magnitude of
parameters in nonlinear dispersion relation, and show how the cosmological
constant depends on the parameters and the energy scale during the inflation at
the grand unification phase transition.
| [
{
"created": "Tue, 29 Sep 2015 04:50:40 GMT",
"version": "v1"
}
] | 2015-09-30 | [
[
"Huang",
"Jung-Jeng",
""
]
] | In Schroedinger picture we study the possible effects of trans-Planckian physics on the quantum evolution of massive non-minimally coupled scalar field in de Sitter space. For the nonlinear Corley-Jacobson type dispersion relations with quartic or sextic correction, we obtain the time evolution of the vacuum state wave functional during slow-roll inflation, and calculate explicitly the corresponding expectation value of vacuum energy density. We find that the vacuum energy density is finite. For the usual dispersion parameter choice, the vacuum energy density for quartic correction to the dispersion relation is larger than for sextic correction, while for some other parameter choices, the vacuum energy density for quartic correction is smaller than for sextic correction. We also use the backreaction to constrain the magnitude of parameters in nonlinear dispersion relation, and show how the cosmological constant depends on the parameters and the energy scale during the inflation at the grand unification phase transition. |
0710.5067 | Michele Castellana | M. Castellana, G. Montani | Physical state condition in Quantum General Relativity as a consequence
of BRST symmetry | 8 pages | Classical and Quantum Gravity 25(10), 105018 (2008); Classical and
Quantum Gravity 25(14): 149802 (2008) | 10.1088/0264-9381/25/10/105018; 10.1088/0264-9381/25/14/149802 | null | gr-qc | null | Quantization of systems with constraints can be carried on with several
methods. In the Dirac formulation the classical generators of gauge
transformations are required to annihilate physical quantum states to ensure
their gauge invariance. Carrying on BRST symmetry it is possible to get a
condition on physical states which, differently from the Dirac method, requires
them to be invariant under the BRST transformation. Employing this method for
the action of general relativity expressed in terms of the spin connection and
tetrad fields with path integral methods, we construct the generator of BRST
transformation associated with the underlying local Lorentz symmetry of the
theory and write a physical state condition consequence of BRST invariance. We
observe that this condition differs form the one obtained within Ashtekar's
canonical formulation, showing how we recover the latter only by a suitable
choice of the gauge fixing functionals. We finally discuss how it should be
possible to obtain all the requested physical state conditions associated with
all the underlying gauge symmetries of the classical theory using our approach.
| [
{
"created": "Fri, 26 Oct 2007 12:11:57 GMT",
"version": "v1"
},
{
"created": "Fri, 26 Oct 2007 20:20:22 GMT",
"version": "v2"
},
{
"created": "Fri, 2 Nov 2007 12:54:15 GMT",
"version": "v3"
},
{
"created": "Wed, 5 Mar 2008 21:12:44 GMT",
"version": "v4"
},
{
"created": "Thu, 13 Mar 2008 12:32:57 GMT",
"version": "v5"
},
{
"created": "Fri, 25 Apr 2008 19:29:08 GMT",
"version": "v6"
}
] | 2014-09-09 | [
[
"Castellana",
"M.",
""
],
[
"Montani",
"G.",
""
]
] | Quantization of systems with constraints can be carried on with several methods. In the Dirac formulation the classical generators of gauge transformations are required to annihilate physical quantum states to ensure their gauge invariance. Carrying on BRST symmetry it is possible to get a condition on physical states which, differently from the Dirac method, requires them to be invariant under the BRST transformation. Employing this method for the action of general relativity expressed in terms of the spin connection and tetrad fields with path integral methods, we construct the generator of BRST transformation associated with the underlying local Lorentz symmetry of the theory and write a physical state condition consequence of BRST invariance. We observe that this condition differs form the one obtained within Ashtekar's canonical formulation, showing how we recover the latter only by a suitable choice of the gauge fixing functionals. We finally discuss how it should be possible to obtain all the requested physical state conditions associated with all the underlying gauge symmetries of the classical theory using our approach. |
1504.01271 | Yungui Gong | Yumei Huang, Yungui Gong, Dicong Liang and Zhu Yi | Thermodynamics of scalar-tensor theory with non-minimally derivative
coupling | 12 pages, no figure, minor corrections | Eur. Phys. J. C 75 (2015) 351 | 10.1140/epjc/s10052-015-3574-7 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | With the usual definitions for the entropy and the temperature associated
with the apparent horizon, we show that the unified first law on the apparent
horizon is equivalent to the Friedmann equation for the scalar--tensor theory
with non-minimally derivative coupling. The second law of thermodynamics on the
apparent horizon is also satisfied. The results support a deep and fundamental
connection between gravitation, thermodynamics, and quantum theory.
| [
{
"created": "Mon, 6 Apr 2015 11:58:25 GMT",
"version": "v1"
},
{
"created": "Tue, 28 Jul 2015 09:25:15 GMT",
"version": "v2"
}
] | 2015-07-31 | [
[
"Huang",
"Yumei",
""
],
[
"Gong",
"Yungui",
""
],
[
"Liang",
"Dicong",
""
],
[
"Yi",
"Zhu",
""
]
] | With the usual definitions for the entropy and the temperature associated with the apparent horizon, we show that the unified first law on the apparent horizon is equivalent to the Friedmann equation for the scalar--tensor theory with non-minimally derivative coupling. The second law of thermodynamics on the apparent horizon is also satisfied. The results support a deep and fundamental connection between gravitation, thermodynamics, and quantum theory. |
2406.09339 | Ulf Leonhardt | Ziv Landau and Ulf Leonhardt | Wigner function method for the Gibbons-Hawking and the Unruh effect | null | null | null | null | gr-qc quant-ph | http://creativecommons.org/licenses/by/4.0/ | An observer at rest with the expanding universe experiences some extra noise
in the quantum vacuum, and so does an accelerated observer in a vacuum at rest
(in Minkowski space). The literature mainly focuses on the ideal cases of
exponential expansion (de-Sitter space) or uniform acceleration (Rindler
trajectories) or both, but the real cosmic expansion is non-exponential and
real accelerations are non-uniform. Here we use the frequency-time Wigner
function of vacuum correlations to define time-dependent spectra. We found
excellent Planck spectra for a class of realistic cosmological models, but also
strongly non-Planckian, negative Wigner functions for a standard scenario
testable with laboratory analogues.
| [
{
"created": "Thu, 13 Jun 2024 17:20:24 GMT",
"version": "v1"
}
] | 2024-06-14 | [
[
"Landau",
"Ziv",
""
],
[
"Leonhardt",
"Ulf",
""
]
] | An observer at rest with the expanding universe experiences some extra noise in the quantum vacuum, and so does an accelerated observer in a vacuum at rest (in Minkowski space). The literature mainly focuses on the ideal cases of exponential expansion (de-Sitter space) or uniform acceleration (Rindler trajectories) or both, but the real cosmic expansion is non-exponential and real accelerations are non-uniform. Here we use the frequency-time Wigner function of vacuum correlations to define time-dependent spectra. We found excellent Planck spectra for a class of realistic cosmological models, but also strongly non-Planckian, negative Wigner functions for a standard scenario testable with laboratory analogues. |
1706.03430 | Yoni BenTov | Yoni BenTov and Joe Swearngin | Gravitational shockwaves on rotating black holes | v4: Substantially shortened (45 pages). Major casualties:
Point-particle limit of field theory and over 100 footnotes. Minor
casualties: Detailed exposition of background material. Corrections: Formal
redefinition of Ricci and energy scalars from traceless tensors, note about
extrinsic curvature, a stray prime, some numerical factors. No results were
harmed. v5: Minor edits. v6: Published | Gen Relativ Gravit (2019) 51: 25 | 10.1007/s10714-019-2512-7 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present an exact solution of Einstein's equation that describes the
gravitational shockwave of a massless particle on the horizon of a Kerr-Newman
black hole. The backreacted metric is of the generalized Kerr-Schild form and
is Type II in the Petrov classification. We show that if the background frame
is aligned with shear-free null geodesics, and if the background Ricci tensor
satisfies a simple condition, then all nonlinearities in the perturbation will
drop out of the curvature scalars. We make heavy use of the method of spin
coefficients (the Newman-Penrose formalism) in its compacted form (the
Geroch-Held-Penrose formalism).
| [
{
"created": "Mon, 12 Jun 2017 01:12:35 GMT",
"version": "v1"
},
{
"created": "Sun, 15 Oct 2017 17:40:58 GMT",
"version": "v2"
},
{
"created": "Tue, 20 Feb 2018 22:15:33 GMT",
"version": "v3"
},
{
"created": "Sat, 2 Jun 2018 22:44:33 GMT",
"version": "v4"
},
{
"created": "Fri, 2 Nov 2018 23:27:30 GMT",
"version": "v5"
},
{
"created": "Tue, 5 Feb 2019 17:19:40 GMT",
"version": "v6"
}
] | 2019-02-06 | [
[
"BenTov",
"Yoni",
""
],
[
"Swearngin",
"Joe",
""
]
] | We present an exact solution of Einstein's equation that describes the gravitational shockwave of a massless particle on the horizon of a Kerr-Newman black hole. The backreacted metric is of the generalized Kerr-Schild form and is Type II in the Petrov classification. We show that if the background frame is aligned with shear-free null geodesics, and if the background Ricci tensor satisfies a simple condition, then all nonlinearities in the perturbation will drop out of the curvature scalars. We make heavy use of the method of spin coefficients (the Newman-Penrose formalism) in its compacted form (the Geroch-Held-Penrose formalism). |
2401.00048 | Maxime Van de Moortel | Yakov Shlapentokh-Rothman and Maxime Van de Moortel | Polynomial time decay for solutions of the Klein--Gordon equation on a
subextremal Reissner--Nordstr\"{o}m black hole | 76 pages, 2 figures | null | null | null | gr-qc math-ph math.AP math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the massive scalar field equation $\Box_{g_{RN}} \phi = m^2 \phi$
on any subextremal Reissner--Nordstr\"{o}m exterior metric $g_{RN}$. We prove
that solutions with localized initial data decay pointwise-in-time at the
polynomial rate $t^{-\frac{5}{6}+\delta}$ in any spatially compact region
(including the event horizon), for some small $ \delta\leq \frac{1}{23} $.
Moreover, assuming the validity of the Exponent Pair Conjecture on exponential
sums in Number Theory, our result implies that decay upper bounds hold at the
rate $t^{-\frac{5}{6}+\epsilon}$, for any arbitrarily small $\epsilon>0$.
In our previous work, we proved that each fixed angular mode decays at the
exact rate $t^{-\frac{5}{6}}$, thus the upper bound $t^{-\frac{5}{6}+\epsilon}$
is sharp, up to a $t^{\epsilon}$ loss. Without the restriction to a fixed
angular mode, the solution turns out to have an unbounded Fourier transform due
to discrete frequencies associated to quasimodes, and caused by the occurrence
of stable timelike trapping. Our analysis nonetheless shows that
inverse-polynomial asymptotics in $t$ still hold after summing over all angular
modes.
| [
{
"created": "Fri, 29 Dec 2023 19:00:09 GMT",
"version": "v1"
}
] | 2024-01-02 | [
[
"Shlapentokh-Rothman",
"Yakov",
""
],
[
"Van de Moortel",
"Maxime",
""
]
] | We consider the massive scalar field equation $\Box_{g_{RN}} \phi = m^2 \phi$ on any subextremal Reissner--Nordstr\"{o}m exterior metric $g_{RN}$. We prove that solutions with localized initial data decay pointwise-in-time at the polynomial rate $t^{-\frac{5}{6}+\delta}$ in any spatially compact region (including the event horizon), for some small $ \delta\leq \frac{1}{23} $. Moreover, assuming the validity of the Exponent Pair Conjecture on exponential sums in Number Theory, our result implies that decay upper bounds hold at the rate $t^{-\frac{5}{6}+\epsilon}$, for any arbitrarily small $\epsilon>0$. In our previous work, we proved that each fixed angular mode decays at the exact rate $t^{-\frac{5}{6}}$, thus the upper bound $t^{-\frac{5}{6}+\epsilon}$ is sharp, up to a $t^{\epsilon}$ loss. Without the restriction to a fixed angular mode, the solution turns out to have an unbounded Fourier transform due to discrete frequencies associated to quasimodes, and caused by the occurrence of stable timelike trapping. Our analysis nonetheless shows that inverse-polynomial asymptotics in $t$ still hold after summing over all angular modes. |
gr-qc/9712097 | Hans-Juergen Schmidt | H.-J. Schmidt | Conformal relations and Hamiltonian formulation of fourth-order gravity | 19 pages, LaTeX, no figures, Grav. and Cosmol. to appear February
1998 | Grav.Cosmol. 3 (1997) 266-274 | null | Preprint UNIPO-MATH-97-December-29 | gr-qc | null | The conformal equivalence of fourth-order gravity following from a non-linear
Lagrangian L(R) to theories of other types is widely known, here we report on a
new conformal equivalence of these theories to theories of the same type but
with different Lagrangian.
For a quantization of fourth-order theories one needs a Hamiltonian
formulation of them. One of the possibilities to do so goes back to
Ostrogradski in 1850. Here we present another possibility: A Hamiltonian H
different from Ostrogradski's one is discussed for the Lagrangian L depending
on first and second order drivatives of the position variable q. We add a
suitable divergence to L. Contrary to other approaches no constraint is needed.
One of the canonical equations becomes equivalent to the fourth-order
Euler-Lagrange equation of L.
Finally, we discuss the stability properties of cosmological models within
fourth-order gravity.
| [
{
"created": "Mon, 29 Dec 1997 09:43:21 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Schmidt",
"H. -J.",
""
]
] | The conformal equivalence of fourth-order gravity following from a non-linear Lagrangian L(R) to theories of other types is widely known, here we report on a new conformal equivalence of these theories to theories of the same type but with different Lagrangian. For a quantization of fourth-order theories one needs a Hamiltonian formulation of them. One of the possibilities to do so goes back to Ostrogradski in 1850. Here we present another possibility: A Hamiltonian H different from Ostrogradski's one is discussed for the Lagrangian L depending on first and second order drivatives of the position variable q. We add a suitable divergence to L. Contrary to other approaches no constraint is needed. One of the canonical equations becomes equivalent to the fourth-order Euler-Lagrange equation of L. Finally, we discuss the stability properties of cosmological models within fourth-order gravity. |
1206.1131 | Li Qin | Li Qin, Guo Deng, Yongge Ma | Path Integrals and Alternative Effective Dynamics in Loop Quantum
Cosmology | 8 pages. arXiv admin note: substantial text overlap with
arXiv:1102.4755 | Commun. Theor. Phys. 57 (2012) 326-332 | 10.1088/0253-6102/57/2/28 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The alternative dynamics of loop quantum cosmology is examined by the path
integral formulation. We consider the spatially flat FRW models with a massless
scalar field, where the alternative quantization inherit more features from
full loop quantum gravity. The path integrals can be formulated in both
timeless and deparameterized frameworks. It turns out that the effective
Hamiltonians derived from the two different viewpoints are equivalent to each
other. Moreover, the first-order modified Friedmann equations are derived and
predict quantum bounces for contracting universe, which coincide with those
obtained in canonical theory.
| [
{
"created": "Wed, 6 Jun 2012 06:52:00 GMT",
"version": "v1"
}
] | 2015-06-05 | [
[
"Qin",
"Li",
""
],
[
"Deng",
"Guo",
""
],
[
"Ma",
"Yongge",
""
]
] | The alternative dynamics of loop quantum cosmology is examined by the path integral formulation. We consider the spatially flat FRW models with a massless scalar field, where the alternative quantization inherit more features from full loop quantum gravity. The path integrals can be formulated in both timeless and deparameterized frameworks. It turns out that the effective Hamiltonians derived from the two different viewpoints are equivalent to each other. Moreover, the first-order modified Friedmann equations are derived and predict quantum bounces for contracting universe, which coincide with those obtained in canonical theory. |
1608.06889 | Joseph Romano | Joseph D. Romano, Neil J. Cornish | Detection methods for stochastic gravitational-wave backgrounds: a
unified treatment | 240 pages, 88 figures | Living Rev Relativ (2017) 20:2 | 10.1007/s41114-017-0004-1 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We review detection methods that are currently in use or have been proposed
to search for a stochastic background of gravitational radiation. We consider
both Bayesian and frequentist searches using ground-based and space-based laser
interferometers, spacecraft Doppler tracking, and pulsar timing arrays; and we
allow for anisotropy, non-Gaussianity, and non-standard polarization states.
Our focus is on relevant data analysis issues, and not on the particular
astrophysical or early Universe sources that might give rise to such
backgrounds. We provide a unified treatment of these searches at the level of
detector response functions, detection sensitivity curves, and, more generally,
at the level of the likelihood function, since the choice of signal and noise
models and prior probability distributions are actually what define the search.
Pedagogical examples are given whenever possible to compare and contrast
different approaches. We have tried to make the article as self-contained and
comprehensive as possible, targeting graduate students and new researchers
looking to enter this field.
| [
{
"created": "Wed, 24 Aug 2016 16:28:38 GMT",
"version": "v1"
},
{
"created": "Fri, 7 Apr 2017 16:55:28 GMT",
"version": "v2"
}
] | 2017-04-11 | [
[
"Romano",
"Joseph D.",
""
],
[
"Cornish",
"Neil J.",
""
]
] | We review detection methods that are currently in use or have been proposed to search for a stochastic background of gravitational radiation. We consider both Bayesian and frequentist searches using ground-based and space-based laser interferometers, spacecraft Doppler tracking, and pulsar timing arrays; and we allow for anisotropy, non-Gaussianity, and non-standard polarization states. Our focus is on relevant data analysis issues, and not on the particular astrophysical or early Universe sources that might give rise to such backgrounds. We provide a unified treatment of these searches at the level of detector response functions, detection sensitivity curves, and, more generally, at the level of the likelihood function, since the choice of signal and noise models and prior probability distributions are actually what define the search. Pedagogical examples are given whenever possible to compare and contrast different approaches. We have tried to make the article as self-contained and comprehensive as possible, targeting graduate students and new researchers looking to enter this field. |
1304.6458 | Georgios Doulis | Florian Beyer, Georgios Doulis, J\"org Frauendiener, Ben Whale | The Spin-2 Equation on Minkowski Background | Contribution to the Proceedings of the Spanish Relativity Meeting ERE
2012, 4 pages | Springer Proc.Math.Stat. 60 (2014) 465-468 | 10.1007/978-3-642-40157-2_71 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The linearised general conformal field equations in their first and second
order form are used to study the behaviour of the spin-2 zero-rest-mass
equation on Minkowski background in the vicinity of space-like infinity.
| [
{
"created": "Wed, 24 Apr 2013 01:13:42 GMT",
"version": "v1"
}
] | 2014-05-20 | [
[
"Beyer",
"Florian",
""
],
[
"Doulis",
"Georgios",
""
],
[
"Frauendiener",
"Jörg",
""
],
[
"Whale",
"Ben",
""
]
] | The linearised general conformal field equations in their first and second order form are used to study the behaviour of the spin-2 zero-rest-mass equation on Minkowski background in the vicinity of space-like infinity. |
1212.6737 | Spiros Cotsakis | Spiros Cotsakis | Structure of infinity in cosmology | v2: 23 pages, various improvements, v3: 21 pages, material on the
Poincar\'e projection in 1D removed as this is now part of arXiv:1301.4778,
v4: matches published version | Int. J. Mod. Phys. D22 (2013) 1330003 | 10.1142/S0218271813300036 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss recent developments related to certain blow up methods suitable
for the analysis of cosmological singularities and asymptotics. We review
results obtained in a variety of currently popular themes and describe ongoing
research about universes with various kinds of extreme states, higher order
gravity, and certain models of braneworlds.
| [
{
"created": "Sun, 30 Dec 2012 15:59:26 GMT",
"version": "v1"
},
{
"created": "Mon, 7 Jan 2013 17:24:44 GMT",
"version": "v2"
},
{
"created": "Tue, 22 Jan 2013 06:58:07 GMT",
"version": "v3"
},
{
"created": "Sat, 9 Feb 2013 13:26:01 GMT",
"version": "v4"
}
] | 2013-10-11 | [
[
"Cotsakis",
"Spiros",
""
]
] | We discuss recent developments related to certain blow up methods suitable for the analysis of cosmological singularities and asymptotics. We review results obtained in a variety of currently popular themes and describe ongoing research about universes with various kinds of extreme states, higher order gravity, and certain models of braneworlds. |
1602.01832 | Shahram Panahiyan | S. H. Hendi, B. Eslam Panah and S. Panahiyan | Topological charged black holes in massive gravity's rainbow and their
thermodynamical analysis through various approaches | 13 pages, 3 figure and 1 table. Matches published version | Phys. Lett. B 769, 191 (2017) | 10.1016/j.physletb.2017.03.051 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Violation of Lorentz invariancy in the high energy quantum gravity motivates
one to consider an energy dependent spacetime with massive deformation of
standard general relativity. In this paper, we take into account an energy
dependent metric in the context of a massive gravity model to obtain exact
solutions. We investigate the geometry of black hole solutions and also
calculate the conserved and thermodynamic quantities, which are fully
reproduced by the analysis performed with the standard techniques. After
examining the validity of the first law of thermodynamics, we conduct a study
regarding the effects of different parameters on thermal stability of the
solutions. In addition, we employ the relation between cosmological constant
and thermodynamical pressure to study the possibility of phase transition.
Interestingly, we will show that for the specific configuration considered in
this paper, van der Waals like behavior is observed for different topology. In
other words, for flat and hyperbolic horizons, similar to spherical horizon, a
second order phase transition and van der Waals like behavior are observed.
Furthermore, we use geometrical method to construct phase space and study phase
transition and bound points for these black holes. Finally, we obtain critical
values in extended phase space through the use of a new method.
| [
{
"created": "Thu, 4 Feb 2016 08:37:24 GMT",
"version": "v1"
},
{
"created": "Wed, 5 Apr 2017 18:53:58 GMT",
"version": "v2"
}
] | 2017-04-07 | [
[
"Hendi",
"S. H.",
""
],
[
"Panah",
"B. Eslam",
""
],
[
"Panahiyan",
"S.",
""
]
] | Violation of Lorentz invariancy in the high energy quantum gravity motivates one to consider an energy dependent spacetime with massive deformation of standard general relativity. In this paper, we take into account an energy dependent metric in the context of a massive gravity model to obtain exact solutions. We investigate the geometry of black hole solutions and also calculate the conserved and thermodynamic quantities, which are fully reproduced by the analysis performed with the standard techniques. After examining the validity of the first law of thermodynamics, we conduct a study regarding the effects of different parameters on thermal stability of the solutions. In addition, we employ the relation between cosmological constant and thermodynamical pressure to study the possibility of phase transition. Interestingly, we will show that for the specific configuration considered in this paper, van der Waals like behavior is observed for different topology. In other words, for flat and hyperbolic horizons, similar to spherical horizon, a second order phase transition and van der Waals like behavior are observed. Furthermore, we use geometrical method to construct phase space and study phase transition and bound points for these black holes. Finally, we obtain critical values in extended phase space through the use of a new method. |
1501.03057 | Alejandra Kandus Dr. | Esteban Calzetta and Alejandra Kandus | Non-conformal evolution of magnetic fields during reheating | 33 pages, no figures. Improvements in the text. Some calculations
sent to appendices. Accepted for publication in JCAP | null | 10.1088/1475-7516/2015/03/045 | null | gr-qc astro-ph.CO hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the evolution of electromagnetic fields coupled to conduction
currents during the reheating era after inflation, and prior to the
establishing of the proton-electron plasma. We assume that the currents may be
described by second order causal hydrodynamics. The resulting theory is not
conformally invariant. The expansion of the Universe produces temperature
gradients which couple to the current and generally oppose Ohmic dissipation.
Although the effect is not strong, it suggests that the unfolding of
hydrodynamic instabilities in these models may follow a different pattern than
in first order theories, and even than in second order theories on non
expanding backgrounds.
| [
{
"created": "Tue, 13 Jan 2015 16:02:02 GMT",
"version": "v1"
},
{
"created": "Mon, 2 Mar 2015 13:14:14 GMT",
"version": "v2"
}
] | 2015-06-23 | [
[
"Calzetta",
"Esteban",
""
],
[
"Kandus",
"Alejandra",
""
]
] | We consider the evolution of electromagnetic fields coupled to conduction currents during the reheating era after inflation, and prior to the establishing of the proton-electron plasma. We assume that the currents may be described by second order causal hydrodynamics. The resulting theory is not conformally invariant. The expansion of the Universe produces temperature gradients which couple to the current and generally oppose Ohmic dissipation. Although the effect is not strong, it suggests that the unfolding of hydrodynamic instabilities in these models may follow a different pattern than in first order theories, and even than in second order theories on non expanding backgrounds. |
2109.06456 | P Ajith | S. Basak, A. Ganguly, K. Haris, S. Kapadia, A. K. Mehta, P. Ajith | Constraints on compact dark matter from gravitational wave microlensing | 9 pages, 12 figures, published version | ApJ Lett. 926 L28 (2022) | 10.3847/2041-8213/ac4dfa | LIGO-P2100321 | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by-nc-nd/4.0/ | If a significant fraction of dark matter is in the form of compact objects,
they will cause microlensing effects in the gravitational wave (GW) signals
observable by LIGO and Virgo. From the non-observation of microlensing
signatures in the binary black hole events from the first two observing runs
and the first half of the third observing run, we constrain the fraction of
compact dark matter in the mass range $10^2-10^5~{M_\odot}$ to be less than
$\simeq 50-80\%$ (details depend on the assumed source population properties
and the Bayesian priors). These modest constraints will be significantly
improved in the next few years with the expected detection of thousands of
binary black hole events, providing a new avenue to probe the nature of dark
matter.
| [
{
"created": "Tue, 14 Sep 2021 05:52:55 GMT",
"version": "v1"
},
{
"created": "Wed, 23 Feb 2022 04:17:52 GMT",
"version": "v2"
}
] | 2022-02-24 | [
[
"Basak",
"S.",
""
],
[
"Ganguly",
"A.",
""
],
[
"Haris",
"K.",
""
],
[
"Kapadia",
"S.",
""
],
[
"Mehta",
"A. K.",
""
],
[
"Ajith",
"P.",
""
]
] | If a significant fraction of dark matter is in the form of compact objects, they will cause microlensing effects in the gravitational wave (GW) signals observable by LIGO and Virgo. From the non-observation of microlensing signatures in the binary black hole events from the first two observing runs and the first half of the third observing run, we constrain the fraction of compact dark matter in the mass range $10^2-10^5~{M_\odot}$ to be less than $\simeq 50-80\%$ (details depend on the assumed source population properties and the Bayesian priors). These modest constraints will be significantly improved in the next few years with the expected detection of thousands of binary black hole events, providing a new avenue to probe the nature of dark matter. |
1707.00955 | Donato Bini | Donato Bini, Andrea Geralico, Robert T. Jantzen | Position determination and strong field parallax effects for photon
emitters in the Schwarzschild spacetime | 21 pages, 5 figures, GRG macros | null | 10.1007/s10714-017-2318-4 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Position determination of photon emitters and associated strong field
parallax effects are investigated using relativistic optics when the photon
orbits are confined to the equatorial plane of the Schwarzschild spacetime. We
assume the emitter is at a fixed space position and the receiver moves along a
circular geodesic orbit. This study requires solving the inverse problem of
determining the (spatial) intersection point of two null geodesic initial data
problems, serving as a simplified model for applications in relativistic
astrometry as well as in radar and satellite communications.
| [
{
"created": "Tue, 4 Jul 2017 13:03:38 GMT",
"version": "v1"
}
] | 2017-11-29 | [
[
"Bini",
"Donato",
""
],
[
"Geralico",
"Andrea",
""
],
[
"Jantzen",
"Robert T.",
""
]
] | Position determination of photon emitters and associated strong field parallax effects are investigated using relativistic optics when the photon orbits are confined to the equatorial plane of the Schwarzschild spacetime. We assume the emitter is at a fixed space position and the receiver moves along a circular geodesic orbit. This study requires solving the inverse problem of determining the (spatial) intersection point of two null geodesic initial data problems, serving as a simplified model for applications in relativistic astrometry as well as in radar and satellite communications. |
2005.07554 | Cosimo Bambi | Carlos A. Benavides-Gallego, Ahmadjon Abdujabbarov, Daniele
Malafarina, Cosimo Bambi | Quasi-harmonic oscillations of charged particles in static axially
symmetric space-times immersed in a uniform magnetic field | 19 pages, 10 figures. v2: fixed some typos | Phys. Rev. D 101, 124024 (2020) | 10.1103/PhysRevD.101.124024 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In continuation of our previous study [Phys. Rev. D 99 (2019) 4, 044012], we
investigate the motion of charged particles in the $\gamma$-metric. We provide
some examples of curled trajectories in the equatorial plane and escape
trajectories outside the equatorial plane. Finally, we consider harmonic
oscillations due to small displacements from stable circular orbits on the
equatorial plane and compute the epicyclic frequencies for different values of
deformation parameter and magnetic field.
| [
{
"created": "Fri, 15 May 2020 14:07:05 GMT",
"version": "v1"
},
{
"created": "Fri, 12 Jun 2020 17:55:17 GMT",
"version": "v2"
}
] | 2020-06-15 | [
[
"Benavides-Gallego",
"Carlos A.",
""
],
[
"Abdujabbarov",
"Ahmadjon",
""
],
[
"Malafarina",
"Daniele",
""
],
[
"Bambi",
"Cosimo",
""
]
] | In continuation of our previous study [Phys. Rev. D 99 (2019) 4, 044012], we investigate the motion of charged particles in the $\gamma$-metric. We provide some examples of curled trajectories in the equatorial plane and escape trajectories outside the equatorial plane. Finally, we consider harmonic oscillations due to small displacements from stable circular orbits on the equatorial plane and compute the epicyclic frequencies for different values of deformation parameter and magnetic field. |
2302.07001 | Tatevik Vardanyan | Tatevik Vardanyan, Claus Kiefer | Quantum-gravitational corrections to the power spectrum for a closed
universe | 7 pages, 1 figure. Contribution to the Proceedings of the DICE2022
meeting, Castiglioncello, September 2022 | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We study the quantum-gravitational corrections to the power spectrum of a
gauge-invariant inflationary scalar perturbations in a closed model of a
universe. We consider canonical quantum gravity as an approach to quantizing
gravity. This leads to the Wheeler-DeWitt equation, which has been studied by
applying a semiclassical Born-Oppenheimer type of approximation. At the
corresponding orders of approximation, we recover both the uncorrected and
quantum-gravitationally corrected Schroedinger equations for the perturbation
modes from which we calculate the quantum-gravitational corrections to the
power spectrum in the slow-roll regime. The results are compared to the power
spectra for the flat model of the universe.
| [
{
"created": "Tue, 14 Feb 2023 12:15:08 GMT",
"version": "v1"
}
] | 2023-02-15 | [
[
"Vardanyan",
"Tatevik",
""
],
[
"Kiefer",
"Claus",
""
]
] | We study the quantum-gravitational corrections to the power spectrum of a gauge-invariant inflationary scalar perturbations in a closed model of a universe. We consider canonical quantum gravity as an approach to quantizing gravity. This leads to the Wheeler-DeWitt equation, which has been studied by applying a semiclassical Born-Oppenheimer type of approximation. At the corresponding orders of approximation, we recover both the uncorrected and quantum-gravitationally corrected Schroedinger equations for the perturbation modes from which we calculate the quantum-gravitational corrections to the power spectrum in the slow-roll regime. The results are compared to the power spectra for the flat model of the universe. |
gr-qc/9802039 | Nese Ozdemir | Y. Enginer, M. Hortacsu and N. Ozdemir | Quantum Fluctuations for Gravitational Impulsive Waves | Submitted to Int. J. Mod. Phys. A | Int.J.Mod.Phys.A13:1201-1212,1998 | 10.1142/S0217751X9800055X | null | gr-qc | null | Quantum fluctuations for a massless scalar field in the background metric of
spherical impulsive gravitational waves through Minkowski and de Sitter spaces
are investigated. It is shown that there exist finite fluctuations for de
Sitter space.
| [
{
"created": "Tue, 17 Feb 1998 07:44:55 GMT",
"version": "v1"
}
] | 2010-11-19 | [
[
"Enginer",
"Y.",
""
],
[
"Hortacsu",
"M.",
""
],
[
"Ozdemir",
"N.",
""
]
] | Quantum fluctuations for a massless scalar field in the background metric of spherical impulsive gravitational waves through Minkowski and de Sitter spaces are investigated. It is shown that there exist finite fluctuations for de Sitter space. |
2307.10801 | Dmitriy Ovchinnikov | R. A. Konoplya, D. Ovchinnikov, B. Ahmedov | Bardeen spacetime as a quantum corrected Schwarzschild black hole:
Quasinormal modes and Hawking radiation | 12 pages, 9 figures | null | null | null | gr-qc astro-ph.HE hep-th | http://creativecommons.org/licenses/by/4.0/ | The Bardeen black hole holds historical significance as the first model of a
regular black hole. Recently, there have been proposed interpretations of the
Bardeen spacetime as quantum corrections to the Schwarzschild solution. Our
study focuses on investigating the quasinormal modes and Hawking radiation of
the Bardeen black hole. We have observed that previous studies on the
quasinormal modes for the Bardeen black hole suffer from inaccuracies that
cannot be neglected. Therefore, we propose accurate calculations of the
quasinormal modes for scalar, electromagnetic, and neutrino fields in the
Bardeen spacetime. Additionally, we have computed the grey-body factors and
analyzed the emission rates of Hawking radiation. Even when the quantum
correction is small and the fundamental mode only slightly differs from its
Schwarzschild value, the first several overtones deviate at an increasingly
stronger rate. This deviation leads to the appearance of overtones with very
small real oscillation frequencies. This outburst of overtones is closely
linked to the fact that the quantum-corrected black hole differs from its
classical limit primarily near the event horizon. Moreover, the intensity of
the Hawking radiation is significantly suppressed (up to three orders of
magnitude) by the quantum correction.
| [
{
"created": "Thu, 20 Jul 2023 12:09:19 GMT",
"version": "v1"
}
] | 2023-07-21 | [
[
"Konoplya",
"R. A.",
""
],
[
"Ovchinnikov",
"D.",
""
],
[
"Ahmedov",
"B.",
""
]
] | The Bardeen black hole holds historical significance as the first model of a regular black hole. Recently, there have been proposed interpretations of the Bardeen spacetime as quantum corrections to the Schwarzschild solution. Our study focuses on investigating the quasinormal modes and Hawking radiation of the Bardeen black hole. We have observed that previous studies on the quasinormal modes for the Bardeen black hole suffer from inaccuracies that cannot be neglected. Therefore, we propose accurate calculations of the quasinormal modes for scalar, electromagnetic, and neutrino fields in the Bardeen spacetime. Additionally, we have computed the grey-body factors and analyzed the emission rates of Hawking radiation. Even when the quantum correction is small and the fundamental mode only slightly differs from its Schwarzschild value, the first several overtones deviate at an increasingly stronger rate. This deviation leads to the appearance of overtones with very small real oscillation frequencies. This outburst of overtones is closely linked to the fact that the quantum-corrected black hole differs from its classical limit primarily near the event horizon. Moreover, the intensity of the Hawking radiation is significantly suppressed (up to three orders of magnitude) by the quantum correction. |
2208.02084 | Oleg Tsupko | Oleg Yu. Tsupko | Shape of higher-order images of equatorial emission rings around a
Schwarzschild black hole: Analytical description with polar curves | See also our previous paper arXiv:2201.01716 | Phys. Rev. D 106, 064033 (2022) | 10.1103/PhysRevD.106.064033 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Higher-order photon rings can be expected to be detected in a more detailed
image of the black hole found in future observations. These rings are lensed
images of the luminous matter surrounding the black hole and are formed by
photons that loop around it. In this paper we have succeeded to derive an
analytical expression for the shape of the higher-order rings in the form that
is most convenient for application: the explicit equation of the curve in polar
coordinates. The formula describes the apparent shape of the higher-order image
of the circular ring with the given radius around Schwarzschild black hole as
viewed by distant observer with an arbitrary inclination. For the derivation,
the strong deflection limit of the gravitational deflection is used. Our
formula is a simple and efficient alternative to the numerical calculation of
ray trajectories, with the main application to studying the shape of $n=2$ and
$n=3$ photon rings.
| [
{
"created": "Wed, 3 Aug 2022 14:09:06 GMT",
"version": "v1"
},
{
"created": "Mon, 19 Sep 2022 00:32:15 GMT",
"version": "v2"
}
] | 2022-09-20 | [
[
"Tsupko",
"Oleg Yu.",
""
]
] | Higher-order photon rings can be expected to be detected in a more detailed image of the black hole found in future observations. These rings are lensed images of the luminous matter surrounding the black hole and are formed by photons that loop around it. In this paper we have succeeded to derive an analytical expression for the shape of the higher-order rings in the form that is most convenient for application: the explicit equation of the curve in polar coordinates. The formula describes the apparent shape of the higher-order image of the circular ring with the given radius around Schwarzschild black hole as viewed by distant observer with an arbitrary inclination. For the derivation, the strong deflection limit of the gravitational deflection is used. Our formula is a simple and efficient alternative to the numerical calculation of ray trajectories, with the main application to studying the shape of $n=2$ and $n=3$ photon rings. |
gr-qc/9603033 | G. Rein | Gerhard Rein (Dept. of Mathematics, Univ. of Munich) | Nonlinear stability of homogeneous models in Newtonian cosmology | 19 pages, latex | Arch.Ration.Mech.Anal. 140 (1997) 335-351 | 10.1007/s002050050070 | null | gr-qc math-ph math.MP | null | We consider the Vlasov-Poisson system in a cosmological setting and prove
nonlinear stability of homogeneous solutions against small, spatially periodic
perturbations in the sup-norm of the spatial mass density. This result is
connected with the question of how large scale structures such as galaxies have
evolved out of the homogeneous state of the early universe.
| [
{
"created": "Thu, 21 Mar 1996 13:49:48 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Rein",
"Gerhard",
"",
"Dept. of Mathematics, Univ. of Munich"
]
] | We consider the Vlasov-Poisson system in a cosmological setting and prove nonlinear stability of homogeneous solutions against small, spatially periodic perturbations in the sup-norm of the spatial mass density. This result is connected with the question of how large scale structures such as galaxies have evolved out of the homogeneous state of the early universe. |
gr-qc/0701045 | Farrukh Fattoyev Jabborovich | B.J. Ahmedov | General relativistic galvano-gravitomagnetic effect in current carrying
conductors | 10 pages | Physics Letters A 256 (1999) 9-14 | 10.1016/S0375-9601(99)00182-6 | null | gr-qc astro-ph | null | The analogy between general relativity and electromagnetism suggests that
there is a galvano-gravitomagnetic effect, which is the gravitational analog of
the Hall effect. This new effect takes place when a current carrying conductor
is placed in a gravitomagnetic field and the conduction electrons moving inside
the conductor are deflected transversally with respect to the current flow. In
connection with this galvano-gravitomagnetic effect, we explore the possibility
of using current carrying conductors for detecting the gravitomagnetic field of
the Earth.
| [
{
"created": "Sun, 7 Jan 2007 11:30:13 GMT",
"version": "v1"
}
] | 2009-11-13 | [
[
"Ahmedov",
"B. J.",
""
]
] | The analogy between general relativity and electromagnetism suggests that there is a galvano-gravitomagnetic effect, which is the gravitational analog of the Hall effect. This new effect takes place when a current carrying conductor is placed in a gravitomagnetic field and the conduction electrons moving inside the conductor are deflected transversally with respect to the current flow. In connection with this galvano-gravitomagnetic effect, we explore the possibility of using current carrying conductors for detecting the gravitomagnetic field of the Earth. |
1710.10845 | Alessia Platania | Alfio Bonanno and Benjamin Koch and Alessia Platania | Gravitational collapse in Quantum Einstein Gravity | 13 pages, 5 figures | null | 10.1007/s10701-018-0195-7 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The existence of spacetime singularities is one of the biggest problems of
nowadays physics. According to Penrose, each physical singularity should be
covered by a "cosmic censor" which prevents any external observer from
perceiving their existence. However, classical models describing the
gravitational collapse usually results in strong curvature singularities, which
can also remain "naked" for a finite amount of advanced time. This proceedings
studies the modifications induced by Asymptotically Safe Gravity on the
gravitational collapse of generic Vaidya spacetimes. It will be shown that, for
any possible choice of the mass function, Quantum Gravity makes the internal
singularity gravitationally weak, thus allowing a continuous extension of the
spacetime beyond the singularity.
| [
{
"created": "Mon, 30 Oct 2017 10:14:54 GMT",
"version": "v1"
}
] | 2018-08-15 | [
[
"Bonanno",
"Alfio",
""
],
[
"Koch",
"Benjamin",
""
],
[
"Platania",
"Alessia",
""
]
] | The existence of spacetime singularities is one of the biggest problems of nowadays physics. According to Penrose, each physical singularity should be covered by a "cosmic censor" which prevents any external observer from perceiving their existence. However, classical models describing the gravitational collapse usually results in strong curvature singularities, which can also remain "naked" for a finite amount of advanced time. This proceedings studies the modifications induced by Asymptotically Safe Gravity on the gravitational collapse of generic Vaidya spacetimes. It will be shown that, for any possible choice of the mass function, Quantum Gravity makes the internal singularity gravitationally weak, thus allowing a continuous extension of the spacetime beyond the singularity. |
1910.04758 | Gianmassimo Tasinato | Cari Powell, Gianmassimo Tasinato | Probing a stationary non-Gaussian background of stochastic gravitational
waves with pulsar timing arrays | 25 pages,13 figures | null | 10.1088/1475-7516/2020/01/017 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We introduce the concept of stationary graviton non-Gaussianity (nG), an
observable that can be probed in terms of 3-point correlation functions of a
stochastic gravitational wave (GW) background. When evaluated in momentum
space, stationary nG corresponds to folded bispectra of graviton nG. We
determine 3-point overlap functions for testing stationary nG with pulsar
timing array GW experiments, and we obtain the corresponding optimal
signal-to-noise ratio. For the first time, we consider 3-point overlap
functions including scalar graviton polarizations (which can be motivated in
theories of modified gravity); moreover, we also calculate 3-point overlap
functions for correlating pulsar timing array with ground based GW detectors.
The value of the optimal signal-to-noise ratio depends on the number and
position of monitored pulsars. We build geometrical quantities characterizing
how such ratio depends on the pulsar system under consideration, and we
evaluate these geometrical parameters using data from the IPTA collaboration.
We quantitatively show how monitoring a large number of pulsars can increase
the signal-to-noise ratio associated with measurements of stationary graviton
nG.
| [
{
"created": "Thu, 10 Oct 2019 12:27:30 GMT",
"version": "v1"
}
] | 2020-01-15 | [
[
"Powell",
"Cari",
""
],
[
"Tasinato",
"Gianmassimo",
""
]
] | We introduce the concept of stationary graviton non-Gaussianity (nG), an observable that can be probed in terms of 3-point correlation functions of a stochastic gravitational wave (GW) background. When evaluated in momentum space, stationary nG corresponds to folded bispectra of graviton nG. We determine 3-point overlap functions for testing stationary nG with pulsar timing array GW experiments, and we obtain the corresponding optimal signal-to-noise ratio. For the first time, we consider 3-point overlap functions including scalar graviton polarizations (which can be motivated in theories of modified gravity); moreover, we also calculate 3-point overlap functions for correlating pulsar timing array with ground based GW detectors. The value of the optimal signal-to-noise ratio depends on the number and position of monitored pulsars. We build geometrical quantities characterizing how such ratio depends on the pulsar system under consideration, and we evaluate these geometrical parameters using data from the IPTA collaboration. We quantitatively show how monitoring a large number of pulsars can increase the signal-to-noise ratio associated with measurements of stationary graviton nG. |
2212.07975 | Oscar Castillo Felisola Dr. | Jos\'e Perdiguero and Oscar Castillo-Felisola | Polynomial affine gravity in 3+1 dimensions | Submitted to the memoirs of the XXIII Chilean Physics Symposium, held
in Valparaiso - Chile, 22-24 novembre 2022. 3 pages | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by-sa/4.0/ | The polynomial affine gravity is an alternative model of gravity whose
fundamental field is the affine connection, and it is invariant under the
complete group of diffeomorphisms. In 3+1 dimensions the field equations
generalise those of Einstein--Hilbert, the coupling constants are
dimensionless, the action has a finite numbers of term, and although the action
does not involve a (fundamental) metric, some metric tensor fields might
\emph{emerge} from the connection. Provided a cosmological ansatz, the
properties of diverse cosmological models are discussed.
| [
{
"created": "Thu, 15 Dec 2022 17:15:17 GMT",
"version": "v1"
}
] | 2022-12-16 | [
[
"Perdiguero",
"José",
""
],
[
"Castillo-Felisola",
"Oscar",
""
]
] | The polynomial affine gravity is an alternative model of gravity whose fundamental field is the affine connection, and it is invariant under the complete group of diffeomorphisms. In 3+1 dimensions the field equations generalise those of Einstein--Hilbert, the coupling constants are dimensionless, the action has a finite numbers of term, and although the action does not involve a (fundamental) metric, some metric tensor fields might \emph{emerge} from the connection. Provided a cosmological ansatz, the properties of diverse cosmological models are discussed. |
gr-qc/9805041 | Brien C. Nolan | Brien C. Nolan | A point mass in an isotropic universe. Existence, uniqueness and basic
properties | 20 pages, to appear in Phys. Rev. D | Phys.Rev. D58 (1998) 064006 | 10.1103/PhysRevD.58.064006 | null | gr-qc | null | Criteria which a space-time must satisfy to represent a point mass embedded
in an open Robertson--Walker (RW) universe are given. It is shown that
McVittie's solution in the case $k=0$ satisfies these criteria, but does not in
the case $k=-1$. Existence of a solution for the case $k=-1$ is proven and its
representation in terms of an elliptic integral is given. The following
properties of this and McVittie's $k=0$ solution are studied; uniqueness,
behaviour at future null infinity, recovery of the RW and Schwarzschild limits,
compliance with energy conditions and the occurence of singularities. Existence
of solutions representing more general spherical objects embedded in a RW
universe is also proven.
| [
{
"created": "Tue, 12 May 1998 08:04:35 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Nolan",
"Brien C.",
""
]
] | Criteria which a space-time must satisfy to represent a point mass embedded in an open Robertson--Walker (RW) universe are given. It is shown that McVittie's solution in the case $k=0$ satisfies these criteria, but does not in the case $k=-1$. Existence of a solution for the case $k=-1$ is proven and its representation in terms of an elliptic integral is given. The following properties of this and McVittie's $k=0$ solution are studied; uniqueness, behaviour at future null infinity, recovery of the RW and Schwarzschild limits, compliance with energy conditions and the occurence of singularities. Existence of solutions representing more general spherical objects embedded in a RW universe is also proven. |
gr-qc/0405106 | Tsutomu Tashiro | Michiyoshi Saito, Hujio Noda, Tsutomu Tashiro | Structure of Extended Loop Wave Function in Quantum Gravity and Operator
Formalism | 20 pages including 2 tables | Int.J.Mod.Phys. A20 (2005) 907-922 | 10.1142/S0217751X05019993 | null | gr-qc | null | The structure of extended loop wave function is investigated in terms of the
operator formalism. It is found that the extended loop wave function is
characterized by the family number and classified by the partition of the
family number. It is pointed out that the constraints to the extended loop
function in quantum gravity exhibit a hierarchy structure.
| [
{
"created": "Wed, 19 May 2004 11:52:49 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Saito",
"Michiyoshi",
""
],
[
"Noda",
"Hujio",
""
],
[
"Tashiro",
"Tsutomu",
""
]
] | The structure of extended loop wave function is investigated in terms of the operator formalism. It is found that the extended loop wave function is characterized by the family number and classified by the partition of the family number. It is pointed out that the constraints to the extended loop function in quantum gravity exhibit a hierarchy structure. |
2408.01476 | Gamal G.L. Nashed | G.G.L. Nashed | Charged solution with equal metric ansatz in Gauss-Bonnet theory coupled
to scalar field | 18 pages, 4 figures | Phys.Dark Univ. 41 (2023) 101260 | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | In the course of this research, we employ the Gauss-Bonnet equation of motion
alongside the scalar field and potential to acquire a fresh solution for a
spherically symmetrical charged black hole. Specifically, we derive this black
hole solution by employing a metric potential where the components are equal,
that is, $g_{tt}=g_{rr}$. In our research, we achieve several accomplishments,
including fixing the characteristics of the scalar field, and the Gauss-Bonnet
term. We thoroughly examine the physical properties associated with such black
hole and show that we have supplementary terms when compared to the
Reissner-Nordstr\"om black hole solution. These additional terms are of the
order $O(\frac{1}{r^6})$ and $O(\frac{1}{r^9})$. The presence of these
supplementary terms can be attributed to the impact of the scalar function
denoted as $\xi$. Such expressions play a crucial role in generating the
multi-horizon black hole solution. The presence of these extra terms
facilitates the derivation of a modified first law of thermodynamics and the
corresponding Smarr relation.
| [
{
"created": "Fri, 2 Aug 2024 08:59:31 GMT",
"version": "v1"
}
] | 2024-08-06 | [
[
"Nashed",
"G. G. L.",
""
]
] | In the course of this research, we employ the Gauss-Bonnet equation of motion alongside the scalar field and potential to acquire a fresh solution for a spherically symmetrical charged black hole. Specifically, we derive this black hole solution by employing a metric potential where the components are equal, that is, $g_{tt}=g_{rr}$. In our research, we achieve several accomplishments, including fixing the characteristics of the scalar field, and the Gauss-Bonnet term. We thoroughly examine the physical properties associated with such black hole and show that we have supplementary terms when compared to the Reissner-Nordstr\"om black hole solution. These additional terms are of the order $O(\frac{1}{r^6})$ and $O(\frac{1}{r^9})$. The presence of these supplementary terms can be attributed to the impact of the scalar function denoted as $\xi$. Such expressions play a crucial role in generating the multi-horizon black hole solution. The presence of these extra terms facilitates the derivation of a modified first law of thermodynamics and the corresponding Smarr relation. |
2303.17630 | Shahar Hod | Shahar Hod | What can a detected photon with a given gravitational redshift tell us
about the maximum density of a compact star? | 5 pages | Physical Review D 107, 064063 (2023) | 10.1103/PhysRevD.107.064063 | null | gr-qc astro-ph.HE hep-th | http://creativecommons.org/licenses/by/4.0/ | Far away observers can in principle bound from below the dimensionless
maximum-density parameter $\Lambda\equiv4\pi R^2\rho_{\text{max}}$ of a compact
star by measuring the gravitational redshift factor
$z\equiv\nu_{\text{e}}/\nu_{\infty}-1$ of photons that were emitted from the
{\it surface} of the star: $\Lambda\geq{3\over2}[1-(1+z)^{-2}]$ [here $R$ is
the radius of the star and $\{\nu_{\text{e}},\nu_{\infty}\}$ are respectively
the frequency of the emitted light as measured at the location of the emission
and by asymptotic observers]. However, if photons that were created somewhere
{\it inside} the star can make their way out and reach the asymptotic
observers, then the measured redshift parameter $z$ may not determine uniquely
the surface properties of the star, thus making the above bound unreliable. In
the present compact paper we prove that in these cases, in which the creation
depth of a detected photon is not known to the far away observers, the
empirically measured redshift parameter can still be used to set a (weaker)
lower bound on the dimensionless density parameter of the observed star:
$\Lambda\geq{3\over2}[1-(1+z)^{-2/3}]$.
| [
{
"created": "Thu, 30 Mar 2023 18:00:02 GMT",
"version": "v1"
}
] | 2023-04-05 | [
[
"Hod",
"Shahar",
""
]
] | Far away observers can in principle bound from below the dimensionless maximum-density parameter $\Lambda\equiv4\pi R^2\rho_{\text{max}}$ of a compact star by measuring the gravitational redshift factor $z\equiv\nu_{\text{e}}/\nu_{\infty}-1$ of photons that were emitted from the {\it surface} of the star: $\Lambda\geq{3\over2}[1-(1+z)^{-2}]$ [here $R$ is the radius of the star and $\{\nu_{\text{e}},\nu_{\infty}\}$ are respectively the frequency of the emitted light as measured at the location of the emission and by asymptotic observers]. However, if photons that were created somewhere {\it inside} the star can make their way out and reach the asymptotic observers, then the measured redshift parameter $z$ may not determine uniquely the surface properties of the star, thus making the above bound unreliable. In the present compact paper we prove that in these cases, in which the creation depth of a detected photon is not known to the far away observers, the empirically measured redshift parameter can still be used to set a (weaker) lower bound on the dimensionless density parameter of the observed star: $\Lambda\geq{3\over2}[1-(1+z)^{-2/3}]$. |
1406.4898 | Igor Pe\~na | Sujoy K. Modak, Leonardo Ort\'iz, Igor Pe\~na, Daniel Sudarsky | Black Holes: Information Loss But No Paradox | 39 pages, 6 figures. Matches accepted version in General Relativity
and Gravitation | Gen Relativ Gravit (2015) 47:120 | 10.1007/s10714-015-1960-y | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The process of black hole evaporation resulting from the Hawking effect has
generated an intense controversy regarding its potential conflict with quantum
mechanics' unitary evolution. In a recent couple of works of a collaboration
involving one of us, we have revised the controversy with the aims of, on the
one hand, clarifying some conceptual issues surrounding it, and, at the same
time, arguing that collapse theories have the potential to offer a satisfactory
resolution of the so-called paradox. Here we show an explicit calculation
supporting this claim using a simplified model of black hole creation and
evaporation, known as the CGHS model, together with a dynamical reduction
theory, known as CSL, and some speculative, but seemingly natural ideas about
the role of quantum gravity in connection with the would-be singularity. This
work represents a specific realization of general ideas first discussed in [1].
| [
{
"created": "Wed, 18 Jun 2014 21:47:52 GMT",
"version": "v1"
},
{
"created": "Mon, 18 Aug 2014 20:50:00 GMT",
"version": "v2"
},
{
"created": "Wed, 30 Sep 2015 04:16:09 GMT",
"version": "v3"
}
] | 2015-10-01 | [
[
"Modak",
"Sujoy K.",
""
],
[
"Ortíz",
"Leonardo",
""
],
[
"Peña",
"Igor",
""
],
[
"Sudarsky",
"Daniel",
""
]
] | The process of black hole evaporation resulting from the Hawking effect has generated an intense controversy regarding its potential conflict with quantum mechanics' unitary evolution. In a recent couple of works of a collaboration involving one of us, we have revised the controversy with the aims of, on the one hand, clarifying some conceptual issues surrounding it, and, at the same time, arguing that collapse theories have the potential to offer a satisfactory resolution of the so-called paradox. Here we show an explicit calculation supporting this claim using a simplified model of black hole creation and evaporation, known as the CGHS model, together with a dynamical reduction theory, known as CSL, and some speculative, but seemingly natural ideas about the role of quantum gravity in connection with the would-be singularity. This work represents a specific realization of general ideas first discussed in [1]. |
0912.4074 | Roberto A. Sussman | Roberto A. Sussman | Quasi-local variables and scalar averaging in LTB dust models | Submitted contribution for the proceedings of the "Invisible Universe
Internationale Confernce", Palais de L'UNESCO, Paris, France, June 29-July 3,
2009. Jean-Michel ALIMI, editor. 10 pages, 2 figures. AIP macros: layoutstyle
8x11single | AIP Conf.Proc.1241:1146-1155,2010 | 10.1063/1.3462612 | null | gr-qc astro-ph.CO math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We introduce quasi--local (QL) scalar variables in spherically symmetric LTB
models. If the QL scalars are defined as functionals, they become weighed
averages that generalize the standard proper volume averages on space slices
orthogonal to the 4-velocity. We examine the connection between QL functions
and functionals and the "back-reaction" term $Q$ in the context of Buchert's
scalar averaging formalism. With the help of the QL scalars we provide rigorous
proof that back--reaction is positive for (i) all LTB models with negative and
asymptotically negative spatial curvature, and (ii) models with positive
curvature decaying to zero asymptotically in the radial direction. We show by
means of qualitative, but robust, arguments that generic LTB models exist,
either with clump or void profiles, for which an "effective" acceleration
associated with Buchert's formalism can mimic the effects of dark energy.
| [
{
"created": "Mon, 21 Dec 2009 03:39:21 GMT",
"version": "v1"
}
] | 2011-01-28 | [
[
"Sussman",
"Roberto A.",
""
]
] | We introduce quasi--local (QL) scalar variables in spherically symmetric LTB models. If the QL scalars are defined as functionals, they become weighed averages that generalize the standard proper volume averages on space slices orthogonal to the 4-velocity. We examine the connection between QL functions and functionals and the "back-reaction" term $Q$ in the context of Buchert's scalar averaging formalism. With the help of the QL scalars we provide rigorous proof that back--reaction is positive for (i) all LTB models with negative and asymptotically negative spatial curvature, and (ii) models with positive curvature decaying to zero asymptotically in the radial direction. We show by means of qualitative, but robust, arguments that generic LTB models exist, either with clump or void profiles, for which an "effective" acceleration associated with Buchert's formalism can mimic the effects of dark energy. |
0808.1223 | Brendan Foster | Julian Barbour, Brendan Z. Foster | Constraints and gauge transformations: Dirac's theorem is not always
valid | 14 pages | null | null | ITP-UU-08/46, SPIN-08/36 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A standard tenet of canonical quantum gravity is that evolution generated by
a Hamiltonian constraint is just a gauge transformation on the phase space and
therefore does not change the physical state. The basis for this belief is a
theorem of Dirac that identifies primary first-class constraints as generators
of physically irrelevant motions. We point out that certain assumptions on
which Dirac based his argument do not hold for reparametrization invariant
systems, and show that the primary Hamiltonian constraint of these systems does
generate physical motion. We show explicitly how the argument fails for systems
described by Jacobi's principle, which has a structure closely resembling that
of general relativity. We defer discussion of general relativity and the
implications for quantum gravity to a later paper.
| [
{
"created": "Fri, 8 Aug 2008 14:33:00 GMT",
"version": "v1"
}
] | 2008-08-12 | [
[
"Barbour",
"Julian",
""
],
[
"Foster",
"Brendan Z.",
""
]
] | A standard tenet of canonical quantum gravity is that evolution generated by a Hamiltonian constraint is just a gauge transformation on the phase space and therefore does not change the physical state. The basis for this belief is a theorem of Dirac that identifies primary first-class constraints as generators of physically irrelevant motions. We point out that certain assumptions on which Dirac based his argument do not hold for reparametrization invariant systems, and show that the primary Hamiltonian constraint of these systems does generate physical motion. We show explicitly how the argument fails for systems described by Jacobi's principle, which has a structure closely resembling that of general relativity. We defer discussion of general relativity and the implications for quantum gravity to a later paper. |
1912.09461 | Barry Wardell | Sarp Akcay, Sam R. Dolan, Chris Kavanagh, Jordan Moxon, Niels
Warburton, Barry Wardell | Dissipation in extreme-mass ratio binaries with a spinning secondary | Minor typos corrected | Phys. Rev. D 102, 064013 (2020) | 10.1103/PhysRevD.102.064013 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present the gravitational-wave flux balance law in an extreme mass-ratio
binary with a spinning secondary. This law relates the flux of energy (angular
momentum) radiated to null infinity and through the event horizon to the local
change in the secondary's orbital energy (angular momentum) for generic
(non-resonant) bound orbits in Kerr spacetime. As an explicit example we
compute these quantities for a spin-aligned body moving on a circular orbit
around a Schwarzschild black hole. We perform this calculation both
analytically, via a high-order post-Newtonian expansion, and numerically in two
different gauges. Using these results we demonstrate explicitly that our new
balance law holds.
| [
{
"created": "Thu, 19 Dec 2019 18:47:11 GMT",
"version": "v1"
},
{
"created": "Tue, 25 Feb 2020 22:46:53 GMT",
"version": "v2"
}
] | 2020-09-16 | [
[
"Akcay",
"Sarp",
""
],
[
"Dolan",
"Sam R.",
""
],
[
"Kavanagh",
"Chris",
""
],
[
"Moxon",
"Jordan",
""
],
[
"Warburton",
"Niels",
""
],
[
"Wardell",
"Barry",
""
]
] | We present the gravitational-wave flux balance law in an extreme mass-ratio binary with a spinning secondary. This law relates the flux of energy (angular momentum) radiated to null infinity and through the event horizon to the local change in the secondary's orbital energy (angular momentum) for generic (non-resonant) bound orbits in Kerr spacetime. As an explicit example we compute these quantities for a spin-aligned body moving on a circular orbit around a Schwarzschild black hole. We perform this calculation both analytically, via a high-order post-Newtonian expansion, and numerically in two different gauges. Using these results we demonstrate explicitly that our new balance law holds. |
gr-qc/0011057 | Doc. Ing. Jozef Sima DRSc. | Jozef Sima and Miroslav Sukenik | Localization of gravitational energy and its potential to evaluation of
hydrogen atom properties | 8 pages, Latex | null | null | SS-00-06 | gr-qc | null | Vaidya metric as an integral part of the Expansive Nondecelerative Universe
(ENU) model enables to localize the energy of gravitational field and,
subsequently, to find a deep interrelationship between quantum mechanics and
the general theory of relativity. In the present paper, stemming from the ENU
model, ionisation energy and energy of hyperfine splitting of the hydrogen
atom, energy of the elementary quantum of action, as well as the proton and
electron mass are independently expressed through the mass of the planckton, Z
and W bosons and fundamental constants.
| [
{
"created": "Thu, 16 Nov 2000 12:53:50 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Sima",
"Jozef",
""
],
[
"Sukenik",
"Miroslav",
""
]
] | Vaidya metric as an integral part of the Expansive Nondecelerative Universe (ENU) model enables to localize the energy of gravitational field and, subsequently, to find a deep interrelationship between quantum mechanics and the general theory of relativity. In the present paper, stemming from the ENU model, ionisation energy and energy of hyperfine splitting of the hydrogen atom, energy of the elementary quantum of action, as well as the proton and electron mass are independently expressed through the mass of the planckton, Z and W bosons and fundamental constants. |
1702.06823 | Ali \"Ovg\"un Dr. | Ali \"Ovg\"un and Ines G. Salako | Thin-Shell Wormholes in Neo-Newtonian Theory | 12 pages, 4 figures. accepted for publication in Mod.Phys.Lett. A | Modern Physics Letters A, Vol. 32 (2017) 1750119 | 10.1142/S021773231750119X | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we constructed an acoustic thin-shell wormhole (ATW) under
neo-Newtonian theory using the Darmois-Israel junction conditions. To determine
the stability of the ATW by applying the cut-and-paste method, we found the
surface density and surface pressure of the ATW under neo-Newtonian
hydrodynamics just after obtaining an analog acoustic neo-Newtonian solution.
We focused on the effects of the neo-Newtonian parameters by performing
stability analyses using different types of fluids, such as a linear barotropic
fluid (LBF), a Chaplygin fluid (CF), a logarithmic fluid (LogF), and a
polytropic fluid (PF). We showed that a fluid with negative energy is required
at the throat to keep the wormhole stable. The ATW can be stable if suitable
values of the neo-Newtonian parameters $\varsigma$, $A$, and $B$ are chosen.
| [
{
"created": "Mon, 20 Feb 2017 09:53:03 GMT",
"version": "v1"
},
{
"created": "Mon, 5 Jun 2017 03:18:38 GMT",
"version": "v2"
}
] | 2017-07-04 | [
[
"Övgün",
"Ali",
""
],
[
"Salako",
"Ines G.",
""
]
] | In this paper, we constructed an acoustic thin-shell wormhole (ATW) under neo-Newtonian theory using the Darmois-Israel junction conditions. To determine the stability of the ATW by applying the cut-and-paste method, we found the surface density and surface pressure of the ATW under neo-Newtonian hydrodynamics just after obtaining an analog acoustic neo-Newtonian solution. We focused on the effects of the neo-Newtonian parameters by performing stability analyses using different types of fluids, such as a linear barotropic fluid (LBF), a Chaplygin fluid (CF), a logarithmic fluid (LogF), and a polytropic fluid (PF). We showed that a fluid with negative energy is required at the throat to keep the wormhole stable. The ATW can be stable if suitable values of the neo-Newtonian parameters $\varsigma$, $A$, and $B$ are chosen. |
1810.03290 | Parthapratim Pradhan | Parthapratim Pradhan | Study of energy extraction and epicyclic frequencies in
Kerr-MOG~(Modified Gravity) black hole | Accepted in EPJC | Eur. Phys. J. C (2019) 79: 401 | 10.1140/epjc/s10052-019-6907-0 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the energy extraction by the Penrose process in Kerr-MOG black
hole~(BH). We derive the gain in energy for Kerr-MOG as \begin{eqnarray} \Delta
{\cal E} \leq
\frac{1}{2}\left(\sqrt{\frac{2}{1+\sqrt{\frac{1}{1+\alpha}-\left(\frac{a}{{\cal
M}}\right)^2}} -\frac{\alpha}{1+\alpha}
\frac{1}{\left(1+\sqrt{\frac{1}{1+\alpha}-\left(\frac{a}{{\cal M}}\right)^2}
\right)^2}}-1\right) \nonumber \end{eqnarray}
Where $a$ is spin parameter, $\alpha$ is MOG parameter and ${\cal M}$ is the
Arnowitt-Deser-Misner(ADM) mass parameter. When $\alpha=0$, we obtain the gain
in energy for Kerr BH. For extremal Kerr-MOG BH, we determine the maximum gain
in energy is $\Delta {\cal E} \leq \frac{1}{2}
\left(\sqrt{\frac{\alpha+2}{1+\alpha}}-1 \right)$. We observe that the MOG
parameter has a crucial role in the energy extraction process and it is in fact
diminishes the value of $\Delta {\cal E}$ in contrast with extremal Kerr BH.
Moreover, we derive the \emph{Wald inequality and the Bardeen-Press-Teukolsky
inequality} for Kerr-MOG BH in contrast with Kerr BH. Furthermore, we describe
the geodesic motion in terms of three fundamental frequencies: the Keplerian
angular frequency, the radial epicyclic frequency and the vertical epicyclic
frequency. These frequencies could be used as a probe of strong gravity near
the black holes.
| [
{
"created": "Mon, 8 Oct 2018 07:24:04 GMT",
"version": "v1"
},
{
"created": "Fri, 17 May 2019 17:32:07 GMT",
"version": "v2"
}
] | 2019-05-20 | [
[
"Pradhan",
"Parthapratim",
""
]
] | We investigate the energy extraction by the Penrose process in Kerr-MOG black hole~(BH). We derive the gain in energy for Kerr-MOG as \begin{eqnarray} \Delta {\cal E} \leq \frac{1}{2}\left(\sqrt{\frac{2}{1+\sqrt{\frac{1}{1+\alpha}-\left(\frac{a}{{\cal M}}\right)^2}} -\frac{\alpha}{1+\alpha} \frac{1}{\left(1+\sqrt{\frac{1}{1+\alpha}-\left(\frac{a}{{\cal M}}\right)^2} \right)^2}}-1\right) \nonumber \end{eqnarray} Where $a$ is spin parameter, $\alpha$ is MOG parameter and ${\cal M}$ is the Arnowitt-Deser-Misner(ADM) mass parameter. When $\alpha=0$, we obtain the gain in energy for Kerr BH. For extremal Kerr-MOG BH, we determine the maximum gain in energy is $\Delta {\cal E} \leq \frac{1}{2} \left(\sqrt{\frac{\alpha+2}{1+\alpha}}-1 \right)$. We observe that the MOG parameter has a crucial role in the energy extraction process and it is in fact diminishes the value of $\Delta {\cal E}$ in contrast with extremal Kerr BH. Moreover, we derive the \emph{Wald inequality and the Bardeen-Press-Teukolsky inequality} for Kerr-MOG BH in contrast with Kerr BH. Furthermore, we describe the geodesic motion in terms of three fundamental frequencies: the Keplerian angular frequency, the radial epicyclic frequency and the vertical epicyclic frequency. These frequencies could be used as a probe of strong gravity near the black holes. |
1406.3232 | Jiri Podolsky | Jiri Podolsky, Robert Svarc | Algebraic structure of Robinson-Trautman and Kundt geometries in
arbitrary dimension | 25 pages, no figures | Class.Quant.Grav.32:015001,2015 | 10.1088/0264-9381/32/1/015001 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the Weyl tensor algebraic structure of a fully general family
of D-dimensional geometries that admit a non-twisting and shear-free null
vector field k. From the coordinate components of the curvature tensor we
explicitly derive all Weyl scalars of various boost weights. This enables us to
give a complete algebraic classification of the metrics in the case when the
optically privileged null direction k is a (multiple) Weyl aligned null
direction (WAND). No field equations are applied, so that the results are valid
not only in Einstein's gravity, including its extension to higher dimensions,
but also in any metric gravitation theory that admits non-twisting and
shear-free spacetimes.
We prove that all such geometries are of type I(b), or more special, and we
derive surprisingly simple necessary and sufficient conditions under which k is
a double, triple or quadruple WAND. All possible algebraically special types,
including the refinement to subtypes, are thus identified, namely II(a), II(b),
II(c), II(d), III(a), III(b), N, O, IIi, IIIi, D, D(a), D(b), D(c), D(d), and
their combinations. Some conditions are identically satisfied in four
dimensions.
We discuss both important subclasses, namely the Kundt family of geometries
with the vanishing expansion (Theta=0) and the Robinson-Trautman family
(Theta\not=0, and in particular Theta=1/r). Finally, we apply Einstein's field
equations and obtain a classification of all Robinson-Trautman vacuum
spacetimes. This reveals fundamental algebraic differences in the D>4 and D=4
cases, namely that in higher dimensions there only exist such spacetimes of
types D(a)=D(abd), D(c)=D(bcd) and O.
| [
{
"created": "Thu, 12 Jun 2014 13:22:25 GMT",
"version": "v1"
}
] | 2015-01-05 | [
[
"Podolsky",
"Jiri",
""
],
[
"Svarc",
"Robert",
""
]
] | We investigate the Weyl tensor algebraic structure of a fully general family of D-dimensional geometries that admit a non-twisting and shear-free null vector field k. From the coordinate components of the curvature tensor we explicitly derive all Weyl scalars of various boost weights. This enables us to give a complete algebraic classification of the metrics in the case when the optically privileged null direction k is a (multiple) Weyl aligned null direction (WAND). No field equations are applied, so that the results are valid not only in Einstein's gravity, including its extension to higher dimensions, but also in any metric gravitation theory that admits non-twisting and shear-free spacetimes. We prove that all such geometries are of type I(b), or more special, and we derive surprisingly simple necessary and sufficient conditions under which k is a double, triple or quadruple WAND. All possible algebraically special types, including the refinement to subtypes, are thus identified, namely II(a), II(b), II(c), II(d), III(a), III(b), N, O, IIi, IIIi, D, D(a), D(b), D(c), D(d), and their combinations. Some conditions are identically satisfied in four dimensions. We discuss both important subclasses, namely the Kundt family of geometries with the vanishing expansion (Theta=0) and the Robinson-Trautman family (Theta\not=0, and in particular Theta=1/r). Finally, we apply Einstein's field equations and obtain a classification of all Robinson-Trautman vacuum spacetimes. This reveals fundamental algebraic differences in the D>4 and D=4 cases, namely that in higher dimensions there only exist such spacetimes of types D(a)=D(abd), D(c)=D(bcd) and O. |
2401.03594 | Gustavo Alejandro Sanchez Herrera | H\'ector Hugo Hern\'andez Hern\'andez and Gustavo Alejandro S\'anchez
Herrera | Singularity removal in a quantum effective evolution of the Mixmaster
cosmological model | 14 pages, 10 figures | null | null | null | gr-qc | http://creativecommons.org/publicdomain/zero/1.0/ | In this work we analyze the evolution of the quantum Mixmaster cosmological
model within an effective approach. In particular, we study the behaviour of
the scale factor and anisotropies of the theory, and determine how it deviates
from its classical counterpart due to quantum back-reaction. Remarkably, we
determine that the effective evolution avoids the initial singularity. The
semiclassical dynamic of the system is obtained from a Hamiltonian in an
extended phase space, whose classical position and momentum variables are the
expectation values of the corresponding quantum operators, as well as of
quantum dispersions and correlations of the system, and is in this framework
that we obtain semiclassical one-particle trajectories.
| [
{
"created": "Sun, 7 Jan 2024 22:27:09 GMT",
"version": "v1"
}
] | 2024-01-09 | [
[
"Hernández",
"Héctor Hugo Hernández",
""
],
[
"Herrera",
"Gustavo Alejandro Sánchez",
""
]
] | In this work we analyze the evolution of the quantum Mixmaster cosmological model within an effective approach. In particular, we study the behaviour of the scale factor and anisotropies of the theory, and determine how it deviates from its classical counterpart due to quantum back-reaction. Remarkably, we determine that the effective evolution avoids the initial singularity. The semiclassical dynamic of the system is obtained from a Hamiltonian in an extended phase space, whose classical position and momentum variables are the expectation values of the corresponding quantum operators, as well as of quantum dispersions and correlations of the system, and is in this framework that we obtain semiclassical one-particle trajectories. |
2308.07098 | Alvaro P. Raposo | Juan J. Morales-Ruiz and \'Alvaro P. Raposo | A note on the geodesic deviation equation for null geodesics in the
Schwarzschild black-hole | 12 pages | null | null | null | gr-qc math-ph math.MP | http://creativecommons.org/licenses/by-nc-sa/4.0/ | We use the Hamiltonian formulation of the geodesic equation in the
Schwarzschild space-time so as to get the variational equation as the
counterpart of the Jacobi equation in this approach. In this context we are
able to apply the Morales-Ramis theorem to link the integrability of the
geodesic equation to the integrability, in the sense of differential Galois
theory, of the variational equation. This link is strong enough to hold even on
geodesics for which the usual conserved quantities fail to be independent, as
is the case of circular geodesics. We show explicitly the particular cases of
some null geodesics and their variational equations.
| [
{
"created": "Mon, 14 Aug 2023 12:20:03 GMT",
"version": "v1"
}
] | 2023-08-15 | [
[
"Morales-Ruiz",
"Juan J.",
""
],
[
"Raposo",
"Álvaro P.",
""
]
] | We use the Hamiltonian formulation of the geodesic equation in the Schwarzschild space-time so as to get the variational equation as the counterpart of the Jacobi equation in this approach. In this context we are able to apply the Morales-Ramis theorem to link the integrability of the geodesic equation to the integrability, in the sense of differential Galois theory, of the variational equation. This link is strong enough to hold even on geodesics for which the usual conserved quantities fail to be independent, as is the case of circular geodesics. We show explicitly the particular cases of some null geodesics and their variational equations. |
gr-qc/0101091 | Tomas Ledvinka | Jiri Bicak | Black Holes under External Influence | based on the plenary talk given at ICGC 2000, Kharagpur, India, 16
pages, 4 figures | Pramana 55:481-496,2000 | 10.1007/s12043-000-0161-7 | null | gr-qc | null | The work on black holes immersed in external fields is reviewed in both
test-field approximation and within exact solutions. In particular we pay
attention to the effect of the expulsion of the flux of external fields across
charged and rotating black holes which are approaching extremal states.
Recently this effect has been shown to occur for black hole solutions in string
theory. We also discuss black holes surrounded by rings and disks and rotating
black holes accelerated by strings.
| [
{
"created": "Tue, 23 Jan 2001 19:55:30 GMT",
"version": "v1"
}
] | 2010-11-19 | [
[
"Bicak",
"Jiri",
""
]
] | The work on black holes immersed in external fields is reviewed in both test-field approximation and within exact solutions. In particular we pay attention to the effect of the expulsion of the flux of external fields across charged and rotating black holes which are approaching extremal states. Recently this effect has been shown to occur for black hole solutions in string theory. We also discuss black holes surrounded by rings and disks and rotating black holes accelerated by strings. |
1706.03767 | Bivudutta Mishra Dr. | B.Mishra, Sankarsan Tarai, S.K. Tripathy | Dynamical features of an anisotropic cosmological model | 11 pages, 7 figures | Indian Journal of Physics, 92(9):1199, 2018 | 10.1007/s12648-018-1194-4 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The dynamical features of Bianchi type $VI_h$ $(BVI_h)$ universe are
investigated in $f(R,T)$ theory of gravity. The field equations and the
physical properties of the model are derived considering a power law expansion
of the universe. The effect of anisotropy on the dynamics of the universe as
well on the energy conditions are studied. The assumed anisotropy of the model
is found to have substantial effects on the energy condition and dynamical
parameters.
| [
{
"created": "Sat, 10 Jun 2017 06:27:31 GMT",
"version": "v1"
},
{
"created": "Mon, 8 Jan 2018 14:32:30 GMT",
"version": "v2"
}
] | 2018-08-09 | [
[
"Mishra",
"B.",
""
],
[
"Tarai",
"Sankarsan",
""
],
[
"Tripathy",
"S. K.",
""
]
] | The dynamical features of Bianchi type $VI_h$ $(BVI_h)$ universe are investigated in $f(R,T)$ theory of gravity. The field equations and the physical properties of the model are derived considering a power law expansion of the universe. The effect of anisotropy on the dynamics of the universe as well on the energy conditions are studied. The assumed anisotropy of the model is found to have substantial effects on the energy condition and dynamical parameters. |
gr-qc/9412042 | null | A. Carlini, D.H. Coule and D.M. Solomons | Quantum versions of Carlini-Miji\'c wormholes | wrong NORDITA preprint reference number changed | null | null | NORDITA-94/75 A | gr-qc hep-th | null | We consider the quantum analogues of wormholes obtained by Carlini and
Miji\'c (CM), who analytically continued closed universe models. To obtain
wormholes when the strong energy condition ($\gamma>2/3$) is satisfied, we are
able to simplify the Wheeler-DeWitt (WDW) equation by using an equivalent
scalar potential which is a function of the scale factor. Such wormholes are
found to be consistent with the Hawking-Page (HP) conjecture for quantum
wormholes as solutions of the WDW equation. In addition to the CM type
wormholes, for a scalar field realization of the potential in the WDW equation
we also obtain quantum wormholes when the strong energy condition is violated.
This violation can be up to an arbitrary large distance from the wormhole
throat, before the violation eventually has to be relaxed in order to have a
flat Euclidean space time. These results give support to the claim of HP that
wormhole solutions are a fairly general property of the WDW equation. However,
by allowing such solutions one might be precluding other more important
properties such as a Lorentzian behaviour and a possible inflationary earlier
stage of our universe.
| [
{
"created": "Thu, 15 Dec 1994 15:55:57 GMT",
"version": "v1"
},
{
"created": "Fri, 16 Dec 1994 08:28:56 GMT",
"version": "v2"
},
{
"created": "Thu, 12 Jan 1995 14:27:33 GMT",
"version": "v3"
}
] | 2009-09-25 | [
[
"Carlini",
"A.",
""
],
[
"Coule",
"D. H.",
""
],
[
"Solomons",
"D. M.",
""
]
] | We consider the quantum analogues of wormholes obtained by Carlini and Miji\'c (CM), who analytically continued closed universe models. To obtain wormholes when the strong energy condition ($\gamma>2/3$) is satisfied, we are able to simplify the Wheeler-DeWitt (WDW) equation by using an equivalent scalar potential which is a function of the scale factor. Such wormholes are found to be consistent with the Hawking-Page (HP) conjecture for quantum wormholes as solutions of the WDW equation. In addition to the CM type wormholes, for a scalar field realization of the potential in the WDW equation we also obtain quantum wormholes when the strong energy condition is violated. This violation can be up to an arbitrary large distance from the wormhole throat, before the violation eventually has to be relaxed in order to have a flat Euclidean space time. These results give support to the claim of HP that wormhole solutions are a fairly general property of the WDW equation. However, by allowing such solutions one might be precluding other more important properties such as a Lorentzian behaviour and a possible inflationary earlier stage of our universe. |
2309.00431 | Erik Amorim | \'Erik Amorim, H{\aa}kan Andr\'easson, Markus Kunze | Proof of the Einstein quadrupole formula for solutions of the
Einstein-Vlasov system close to Minkowski spacetime | null | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We rigorously derive the quadrupole formula within the context of the
Einstein-Vlasov system. The main contribution of this work is an estimate of
the remainder terms, derived from well-defined assumptions, with explicitly
stated error terms that depend on the solution's boundedness and decay
properties, and the distance to the source. The assumptions are linked to
established properties of global solutions of the Einstein-Vlasov system as in
\cite{LT}. Prior derivations of the quadrupole formula have relied on
post-Newtonian analysis and lacked comparisons with global solution properties.
The importance of the no-incoming-radiation condition is emphasized
underscoring the need for solutions satisfying this condition. This work thus
addresses the limitations of existing results and provides motivation for
further research on global solution properties of the Einstein-Vlasov system.
| [
{
"created": "Fri, 1 Sep 2023 12:52:20 GMT",
"version": "v1"
}
] | 2023-09-04 | [
[
"Amorim",
"Érik",
""
],
[
"Andréasson",
"Håkan",
""
],
[
"Kunze",
"Markus",
""
]
] | We rigorously derive the quadrupole formula within the context of the Einstein-Vlasov system. The main contribution of this work is an estimate of the remainder terms, derived from well-defined assumptions, with explicitly stated error terms that depend on the solution's boundedness and decay properties, and the distance to the source. The assumptions are linked to established properties of global solutions of the Einstein-Vlasov system as in \cite{LT}. Prior derivations of the quadrupole formula have relied on post-Newtonian analysis and lacked comparisons with global solution properties. The importance of the no-incoming-radiation condition is emphasized underscoring the need for solutions satisfying this condition. This work thus addresses the limitations of existing results and provides motivation for further research on global solution properties of the Einstein-Vlasov system. |
0708.3852 | Eduardo V. Correa Silva | G. Oliveira Neto, E.V. Correa Silva, N.A. Lemos, G.A. Monerat | Probing singularities in quantum cosmology with curvature scalars | 9 pages, 6 figures | Phys.Lett.A373:2012-2016,2009 | 10.1016/j.physleta.2009.04.002 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide further evidence that the canonical quantization of cosmological
models eliminates the classical Big Bang singularity, using the {\it
DeBroglie-Bohm} interpretation of quantum mechanics. The usual criterion for
absence of the Big Bang singularity in Friedmann-Robertson-Walker quantum
cosmological models is the non-vanishing of the expectation value of the scale
factor. We compute the `local expectation value' of the Ricci and Kretschmann
scalars, for some quantum FRW models. We show that they are finite for all
time. Since these scalars are elements of general scalar polynomials in the
metric and the Riemann tensor, this result indicates that, for the quantum
models treated here, the `local expectation value' of these general scalar
polynomials should be finite everywhere. Therefore, we have further evidence
that the quantization of the models treated here eliminates the classical Big
Bang singularity. PACS: 04.40.Nr, 04.60.Ds, 98.80.Qc.
| [
{
"created": "Tue, 28 Aug 2007 20:13:48 GMT",
"version": "v1"
},
{
"created": "Wed, 10 Mar 2010 01:54:21 GMT",
"version": "v2"
}
] | 2014-11-18 | [
[
"Neto",
"G. Oliveira",
""
],
[
"Silva",
"E. V. Correa",
""
],
[
"Lemos",
"N. A.",
""
],
[
"Monerat",
"G. A.",
""
]
] | We provide further evidence that the canonical quantization of cosmological models eliminates the classical Big Bang singularity, using the {\it DeBroglie-Bohm} interpretation of quantum mechanics. The usual criterion for absence of the Big Bang singularity in Friedmann-Robertson-Walker quantum cosmological models is the non-vanishing of the expectation value of the scale factor. We compute the `local expectation value' of the Ricci and Kretschmann scalars, for some quantum FRW models. We show that they are finite for all time. Since these scalars are elements of general scalar polynomials in the metric and the Riemann tensor, this result indicates that, for the quantum models treated here, the `local expectation value' of these general scalar polynomials should be finite everywhere. Therefore, we have further evidence that the quantization of the models treated here eliminates the classical Big Bang singularity. PACS: 04.40.Nr, 04.60.Ds, 98.80.Qc. |
1510.06012 | P. A. Gonzalez | Ramon Becar, P. A. Gonzalez and Yerko Vasquez | Quasinormal modes of Four Dimensional Topological Nonlinear Charged
Lifshitz Black Holes | 13 pages, 2 figures and 6 Tables. arXiv admin note: text overlap with
arXiv:1404.3172, arXiv:1510.04605 | null | 10.1140/epjc/s10052-016-3937-8 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study scalar perturbations of four dimensional topological nonlinear
charged Lifshitz black holes with spherical and plane transverse sections, and
we find numerically the quasinormal modes for scalar fields. Then, we study the
stability of these black holes under massive and massless scalar field
perturbations. We focus our study on the dependence of the dynamical exponent,
the nonlinear exponent, the angular momentum and the mass of the scalar field
in the modes. It is found that the modes are overdamped depending strongly on
the dynamical exponent and the angular momentum of the scalar field for a
spherical transverse section. In constrast, for plane transverse sections the
modes are always overdamped.
| [
{
"created": "Tue, 20 Oct 2015 19:15:35 GMT",
"version": "v1"
}
] | 2016-03-23 | [
[
"Becar",
"Ramon",
""
],
[
"Gonzalez",
"P. A.",
""
],
[
"Vasquez",
"Yerko",
""
]
] | We study scalar perturbations of four dimensional topological nonlinear charged Lifshitz black holes with spherical and plane transverse sections, and we find numerically the quasinormal modes for scalar fields. Then, we study the stability of these black holes under massive and massless scalar field perturbations. We focus our study on the dependence of the dynamical exponent, the nonlinear exponent, the angular momentum and the mass of the scalar field in the modes. It is found that the modes are overdamped depending strongly on the dynamical exponent and the angular momentum of the scalar field for a spherical transverse section. In constrast, for plane transverse sections the modes are always overdamped. |
gr-qc/0504025 | Emil M. Prodanov | Rossen I. Ivanov and Emil M. Prodanov | Pseudo-Newtonian Potential for Charged Particle in Kerr-Newman Geometry | 8 pages | Phys.Lett. B611 (2005) 34-38 | 10.1016/j.physletb.2005.02.047 | null | gr-qc | null | We consider the equatorial circular motion of a test particle of specific
charge q/m << 1 in the Kerr-Newman geometry of a rotating charged black hole.
We find the particle's conserved energy and conserved projection of the angular
momentum on the black hole's axis of rotation as corrections, in leading order
of q/m, to the corresponding energy and angular momentum of a neutral particle.
We determine the centripetal force acting on the test particle and,
consequently, we find a classical pseudo-Newtonian potential with which one can
mimic this general relativistic problem.
| [
{
"created": "Wed, 6 Apr 2005 22:07:31 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Ivanov",
"Rossen I.",
""
],
[
"Prodanov",
"Emil M.",
""
]
] | We consider the equatorial circular motion of a test particle of specific charge q/m << 1 in the Kerr-Newman geometry of a rotating charged black hole. We find the particle's conserved energy and conserved projection of the angular momentum on the black hole's axis of rotation as corrections, in leading order of q/m, to the corresponding energy and angular momentum of a neutral particle. We determine the centripetal force acting on the test particle and, consequently, we find a classical pseudo-Newtonian potential with which one can mimic this general relativistic problem. |
gr-qc/0403042 | Piotr T. Chru\'sciel | R. Beig, P.T. Chrusciel, R. Schoen | KIDs are non-generic | latex2e, 38 pages in A4 now, minor corrections throughout | Annales Henri Poincare 6 (2005) 155-194 | 10.1007/s00023-005-0202-3 | ESI preprint 1464 | gr-qc | null | We prove that generic solutions of the vacuum constraint Einstein equations
do not possess any global or local space-time Killing vectors, on an
asymptotically flat Cauchy surface, or on a compact Cauchy surface with mean
curvature close to a constant, or for CMC asymptotically hyperbolic initial
data sets. More generally, we show that non-existence of global symmetries
implies, generically, non-existence of local ones. As part of the argument, we
prove that generic metrics do not possess any local or global conformal Killing
vectors.
| [
{
"created": "Wed, 10 Mar 2004 20:51:18 GMT",
"version": "v1"
},
{
"created": "Wed, 6 Oct 2004 07:25:20 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Beig",
"R.",
""
],
[
"Chrusciel",
"P. T.",
""
],
[
"Schoen",
"R.",
""
]
] | We prove that generic solutions of the vacuum constraint Einstein equations do not possess any global or local space-time Killing vectors, on an asymptotically flat Cauchy surface, or on a compact Cauchy surface with mean curvature close to a constant, or for CMC asymptotically hyperbolic initial data sets. More generally, we show that non-existence of global symmetries implies, generically, non-existence of local ones. As part of the argument, we prove that generic metrics do not possess any local or global conformal Killing vectors. |
gr-qc/9602036 | Donald Marolf | Donald Marolf | Interpolating Between Topologies: Casimir Energies | 7 pages Revtex, Note and reference added | Phys.Lett. B392 (1997) 287-290 | 10.1016/S0370-2693(96)01577-8 | UCSBTH-96-03 | gr-qc hep-th | null | A set of models is considered which, in a certain sense, interpolates between
1+1 free quantum field theories on topologically distinct backgrounds. The
intermediate models may be termed free quantum field theories, though they are
certainly not local. Their ground state energies are computed and shown to be
finite. The possible relevance to changing spacetime topologies is discussed.
| [
{
"created": "Sun, 18 Feb 1996 01:09:41 GMT",
"version": "v1"
},
{
"created": "Thu, 22 Feb 1996 01:58:33 GMT",
"version": "v2"
},
{
"created": "Tue, 4 Mar 1997 02:05:47 GMT",
"version": "v3"
}
] | 2009-10-28 | [
[
"Marolf",
"Donald",
""
]
] | A set of models is considered which, in a certain sense, interpolates between 1+1 free quantum field theories on topologically distinct backgrounds. The intermediate models may be termed free quantum field theories, though they are certainly not local. Their ground state energies are computed and shown to be finite. The possible relevance to changing spacetime topologies is discussed. |
gr-qc/0605152 | Vh Satheeshkumar | V. H. Satheeshkumar and P. K. Suresh | Understanding Gravity: Some Extra Dimensional Perspectives | 21 pages | ISRN Astronomy and Astrophysics, Volume 2011 (2011), Article ID
131473 | 10.5402/2011/131473 | null | gr-qc | http://creativecommons.org/licenses/by/3.0/ | Gravity is one of the most inexplicable forces of nature, controlling
everything, from the expansion of the Universe to the ebb and flow of ocean
tides. The search for the laws of motion and gravitation began more than two
thousand years ago but still we do not have the complete picture of it. In this
article, we have outlined how our understanding of gravity is changing
drastically with time and how the previous explanations have shaped the most
recent developments in the field like superstrings and braneworlds.
| [
{
"created": "Wed, 31 May 2006 18:19:15 GMT",
"version": "v1"
},
{
"created": "Wed, 25 Jan 2012 02:15:26 GMT",
"version": "v2"
}
] | 2012-01-26 | [
[
"Satheeshkumar",
"V. H.",
""
],
[
"Suresh",
"P. K.",
""
]
] | Gravity is one of the most inexplicable forces of nature, controlling everything, from the expansion of the Universe to the ebb and flow of ocean tides. The search for the laws of motion and gravitation began more than two thousand years ago but still we do not have the complete picture of it. In this article, we have outlined how our understanding of gravity is changing drastically with time and how the previous explanations have shaped the most recent developments in the field like superstrings and braneworlds. |
gr-qc/9403045 | null | G. Wanders | Fermion emission in a two-dimensional black hole space-time | 34 pages in LaTeX with fleqn, math and texdraw, 1 Fig. available on
request, UNIL-TP-1/94 | Phys.Rev. D50 (1994) 2731-2743 | 10.1103/PhysRevD.50.2731 | null | gr-qc hep-th | null | We investigate massless fermion production by a two-dimensional dilatonic
black hole. Our analysis is based on the Bogoliubov transformation relating the
outgoing fermion field observed outside the black hole horizon to the incoming
field present before the black hole creation. It takes full account of the fact
that the transformation is neither invertible nor unitarily implementable. The
particle content of the outgoing radiation is specified by means of inclusive
probabilities for the detection of sets of outgoing fermions and antifermions
in given states. For states localized near the horizon these probabilities
characterize a thermal equilibrium state. The way the probabilities become
thermal as one approaches the horizon is discussed in detail.
| [
{
"created": "Tue, 22 Mar 1994 13:29:53 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Wanders",
"G.",
""
]
] | We investigate massless fermion production by a two-dimensional dilatonic black hole. Our analysis is based on the Bogoliubov transformation relating the outgoing fermion field observed outside the black hole horizon to the incoming field present before the black hole creation. It takes full account of the fact that the transformation is neither invertible nor unitarily implementable. The particle content of the outgoing radiation is specified by means of inclusive probabilities for the detection of sets of outgoing fermions and antifermions in given states. For states localized near the horizon these probabilities characterize a thermal equilibrium state. The way the probabilities become thermal as one approaches the horizon is discussed in detail. |
gr-qc/0403036 | Yuichirou Sekiguchi | Yu-ichirou Sekiguchi and Masaru Shibata | New criterion for direct black hole formation in rapidly rotating
stellar collapse | submitted to PRD | Phys.Rev. D70 (2004) 084005 | 10.1103/PhysRevD.70.084005 | null | gr-qc astro-ph | null | We study gravitational collapse of rapidly rotating relativistic polytropes
of the adiabatic index $\Gamma = 1.5$ and 2, in which the spin parameter $q
\equiv J/M^{2} > 1$ where $J$ and $M$ are total angular momentum and
gravitational mass, in full general relativity.
First, analyzing initial distributions of the mass and the spin parameter
inside stars, we predict the final outcome after the collapse. Then, we perform
fully general relativistic simulations on assumption of axial and equatorial
symmetries and confirm our predictions. As a result of simulations, we find
that in contrast with the previous belief, even for stars with $q > 1$, the
collapse proceeds to form a seed black hole at central region, and the seed
black hole subsequently grows as the ambient fluids accrete onto it. We also
find that growth of angular momentum and mass of the seed black hole can be
approximately determined from the initial profiles of the density and the
specific angular momentum. We define an effective spin parameter at the central
region of the stars, $q_{c}$, and propose a new criterion for black hole
formation as $q_{c} \alt 1$. Plausible reasons for the discrepancy between our
and previous results are clarified.
| [
{
"created": "Tue, 9 Mar 2004 03:59:22 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Sekiguchi",
"Yu-ichirou",
""
],
[
"Shibata",
"Masaru",
""
]
] | We study gravitational collapse of rapidly rotating relativistic polytropes of the adiabatic index $\Gamma = 1.5$ and 2, in which the spin parameter $q \equiv J/M^{2} > 1$ where $J$ and $M$ are total angular momentum and gravitational mass, in full general relativity. First, analyzing initial distributions of the mass and the spin parameter inside stars, we predict the final outcome after the collapse. Then, we perform fully general relativistic simulations on assumption of axial and equatorial symmetries and confirm our predictions. As a result of simulations, we find that in contrast with the previous belief, even for stars with $q > 1$, the collapse proceeds to form a seed black hole at central region, and the seed black hole subsequently grows as the ambient fluids accrete onto it. We also find that growth of angular momentum and mass of the seed black hole can be approximately determined from the initial profiles of the density and the specific angular momentum. We define an effective spin parameter at the central region of the stars, $q_{c}$, and propose a new criterion for black hole formation as $q_{c} \alt 1$. Plausible reasons for the discrepancy between our and previous results are clarified. |
1506.02123 | Titus K Mathew | Titus K. Mathew, Chinthak Murali and Shejeelammal J | Evolution of entropic dark energy and its phantom nature | 14 pages, 8 figures | null | 10.1142/S0217732316500711 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Assuming the form of the entropic dark energy as arises form the surface term
in the Einstein-Hilbert's action, it's evolution were analyzed in an expanding
flat universe. The model parameters were evaluated by constraining model using
the Union data on Type Ia supernovae. We found that the model predicts an early
decelerated phase and a later accelerated phase at the background level. The
evolution of the Hubble parameter, dark energy density, equation of state
parameter and deceleration parameter were obtained. The model is diagnosed with
$Om$ parameter. The model is hardly seems to be supporting the linear
perturbation growth for the structure formation. We also found that the
entropic dark energy shows phantom nature for redshifts $z<0.257.$ During the
phantom epoch, the model predicts big-rip effect at which both the scale factor
of expansion and the dark energy density become infinitely large and the big
rip time is found to be around 36 Giga Years from now.
| [
{
"created": "Sat, 6 Jun 2015 06:55:23 GMT",
"version": "v1"
},
{
"created": "Tue, 23 Jun 2015 07:18:50 GMT",
"version": "v2"
},
{
"created": "Thu, 10 Dec 2015 06:43:49 GMT",
"version": "v3"
}
] | 2016-04-27 | [
[
"Mathew",
"Titus K.",
""
],
[
"Murali",
"Chinthak",
""
],
[
"J",
"Shejeelammal",
""
]
] | Assuming the form of the entropic dark energy as arises form the surface term in the Einstein-Hilbert's action, it's evolution were analyzed in an expanding flat universe. The model parameters were evaluated by constraining model using the Union data on Type Ia supernovae. We found that the model predicts an early decelerated phase and a later accelerated phase at the background level. The evolution of the Hubble parameter, dark energy density, equation of state parameter and deceleration parameter were obtained. The model is diagnosed with $Om$ parameter. The model is hardly seems to be supporting the linear perturbation growth for the structure formation. We also found that the entropic dark energy shows phantom nature for redshifts $z<0.257.$ During the phantom epoch, the model predicts big-rip effect at which both the scale factor of expansion and the dark energy density become infinitely large and the big rip time is found to be around 36 Giga Years from now. |
gr-qc/0412027 | J. Ponce de Leon | J. Ponce de Leon | Testing Dark Energy and Cardassian Expansion for Causality | null | null | null | null | gr-qc | null | Causality principle is a powerful criterion that allows us to discriminate
between what is possible or not. In this paper we study the transition from
decelerated to accelerated expansion in the context of Cardassian and dark
energy models. We distinguish two important events during the transition. The
first one is the end of the matter-dominated phase, which occurs at some time
$t_{eq}$. The second one is the actual crossover from deceleration to
acceleration, which occurs at some $t_{T}$. Causality requires $t_{T} \geq
t_{eq}$. We demonstrate that dark energy models, with constant $w$, and
Cardassian expansion, are compatible with causality only if $(\Omega_{M} -
\bar{q}) \leq 1/2$. However, observational data indicate that the most probable
option is $(\Omega_{M} - \bar{q}) > 1/2$. Consequently, the transition from
deceleration to acceleration in dark energy and Cardassian models occurs before
the matter-dominated epoch comes to an end, i.e., $t_{eq} > t_{T}$. Which
contradicts causality principle.
| [
{
"created": "Tue, 7 Dec 2004 03:20:32 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"de Leon",
"J. Ponce",
""
]
] | Causality principle is a powerful criterion that allows us to discriminate between what is possible or not. In this paper we study the transition from decelerated to accelerated expansion in the context of Cardassian and dark energy models. We distinguish two important events during the transition. The first one is the end of the matter-dominated phase, which occurs at some time $t_{eq}$. The second one is the actual crossover from deceleration to acceleration, which occurs at some $t_{T}$. Causality requires $t_{T} \geq t_{eq}$. We demonstrate that dark energy models, with constant $w$, and Cardassian expansion, are compatible with causality only if $(\Omega_{M} - \bar{q}) \leq 1/2$. However, observational data indicate that the most probable option is $(\Omega_{M} - \bar{q}) > 1/2$. Consequently, the transition from deceleration to acceleration in dark energy and Cardassian models occurs before the matter-dominated epoch comes to an end, i.e., $t_{eq} > t_{T}$. Which contradicts causality principle. |
1505.07255 | Luis Acedo Rodr\'iguez | L. Acedo and M. M. Tung | Electromagnetic Waves in a Uniform Gravitational Field and Planck's
Postulate | 16 pages, 2 figures | Eur. J. Phys. 33 1073 (2012) | 10.1088/0143-0807/33/5/1073 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The gravitational redshift forms the central part of the majority of the
classical tests for the general theory of relativity. It could be successfully
checked even in laboratory experiments on the earth's surface. The standard
derivation of this effect is based on the distortion of the local structure of
spacetime induced by large masses. The resulting gravitational time-dilation
near these masses gives rise to a frequency change of any periodic process,
including electromagnetic oscillations as the wave propagates across the
gravitational field. This phenomenon can be tackled with classical
electrodynamics assuming a curved spacetime background and Maxwell's equations
in a generally covariant form. In the present paper, we show that in a
classical field-theoretical context the gravitational redshift can be
interpreted as the propagation of electromagnetic waves in a medium with
corresponding conductivity $\sigma=g/(\mu_0 c^3)$, where $g$ is the
gravitational acceleration and $\mu_0$ is the vacuum magnetic permeability.
Moreover, the energy density of the wave remains proportional to its frequency
in agreement with Planck's postulate.
| [
{
"created": "Wed, 27 May 2015 10:22:31 GMT",
"version": "v1"
}
] | 2015-05-28 | [
[
"Acedo",
"L.",
""
],
[
"Tung",
"M. M.",
""
]
] | The gravitational redshift forms the central part of the majority of the classical tests for the general theory of relativity. It could be successfully checked even in laboratory experiments on the earth's surface. The standard derivation of this effect is based on the distortion of the local structure of spacetime induced by large masses. The resulting gravitational time-dilation near these masses gives rise to a frequency change of any periodic process, including electromagnetic oscillations as the wave propagates across the gravitational field. This phenomenon can be tackled with classical electrodynamics assuming a curved spacetime background and Maxwell's equations in a generally covariant form. In the present paper, we show that in a classical field-theoretical context the gravitational redshift can be interpreted as the propagation of electromagnetic waves in a medium with corresponding conductivity $\sigma=g/(\mu_0 c^3)$, where $g$ is the gravitational acceleration and $\mu_0$ is the vacuum magnetic permeability. Moreover, the energy density of the wave remains proportional to its frequency in agreement with Planck's postulate. |
2207.09967 | Pasquale Bosso | Pasquale Bosso, Mitja Fridman, Giuseppe Gaetano Luciano | Dark Matter as an effect of a minimal length | 8 pages, 1 figure | null | null | null | gr-qc hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we consider the implications of a phenomenological model of
quantum gravitational effects related to a minimal length, implemented via the
Generalized Uncertainty Principle. Such effects are applied to the
Bekenstein-Hawking entropy to derive a modified law of gravity through
Verlinde's conjecture. Implications on galactic scales, and in particular on
the shape of rotational curves, are investigated, exploring the possibility to
mimic dark matter-like effects via a minimal length.
| [
{
"created": "Wed, 20 Jul 2022 15:19:49 GMT",
"version": "v1"
}
] | 2022-07-21 | [
[
"Bosso",
"Pasquale",
""
],
[
"Fridman",
"Mitja",
""
],
[
"Luciano",
"Giuseppe Gaetano",
""
]
] | In this work, we consider the implications of a phenomenological model of quantum gravitational effects related to a minimal length, implemented via the Generalized Uncertainty Principle. Such effects are applied to the Bekenstein-Hawking entropy to derive a modified law of gravity through Verlinde's conjecture. Implications on galactic scales, and in particular on the shape of rotational curves, are investigated, exploring the possibility to mimic dark matter-like effects via a minimal length. |
1003.1860 | Niels Warburton | Niels Warburton and Leor Barack | Self force on a scalar charge in Kerr spacetime: circular equatorial
orbits | 22 pages, 10 eps figures, correct horizon boundary condition | Phys.Rev.D81:084039,2010 | 10.1103/PhysRevD.81.084039 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a calculation of the scalar field self-force (SSF) acting on a
scalar-charge particle in a strong-field orbit around a Kerr black hole. Our
calculation specializes to circular and equatorial geodesic orbits. The
analysis is an implementation of the standard mode-sum regularization scheme:
We first calculate the multipole modes of the scalar-field perturbation using
numerical integration in the frequency domain, and then apply a certain
regularization procedure to each of the modes. The dissipative piece of the SSF
is found to be consistent with the flux of energy and angular momentum carried
by the scalar waves through the event horizon and out to infinity. The
conservative (radial) component of the SSF is found to be attractive (inward
pointing) for $r_0>r_{\rm c}(a)$ and repulsive (outward pointing) for
$r_0<r_{\rm c}(a)$, where $a$ is the Kerr spin parameter, $r_0$ is the
Boyer-Lindquist orbital radius, and $r_{\rm c}$ is a critical $a$-dependent
radius at which the conservative SSF vanishes. When the motion is retrograde
the conservative SSF is repulsive for all $r_0$ (as in the Schwarzschild case).
The dominant conservative effect of the SSF in Schwarzschild spacetime is known
to be of 3rd post-Newtonian (PN) order (with a logarithmic running). Our
numerical results suggest that the leading-order PN correction due to the black
hole's spin arises from spin-orbit coupling at 3PN, which dominates the overall
SSF effect at large $r_0$. In PN language, the change-of-sign of the radial SSF
is attributed to an interplay between the spin-orbit term ($\propto
-ar_0^{-4.5}$) and the "Schwarzschild" term ($\propto r_0^{-5}\log r_0$).
| [
{
"created": "Tue, 9 Mar 2010 12:34:43 GMT",
"version": "v1"
},
{
"created": "Wed, 21 Apr 2010 13:00:46 GMT",
"version": "v2"
},
{
"created": "Mon, 29 Jun 2015 07:51:24 GMT",
"version": "v3"
}
] | 2015-06-30 | [
[
"Warburton",
"Niels",
""
],
[
"Barack",
"Leor",
""
]
] | We present a calculation of the scalar field self-force (SSF) acting on a scalar-charge particle in a strong-field orbit around a Kerr black hole. Our calculation specializes to circular and equatorial geodesic orbits. The analysis is an implementation of the standard mode-sum regularization scheme: We first calculate the multipole modes of the scalar-field perturbation using numerical integration in the frequency domain, and then apply a certain regularization procedure to each of the modes. The dissipative piece of the SSF is found to be consistent with the flux of energy and angular momentum carried by the scalar waves through the event horizon and out to infinity. The conservative (radial) component of the SSF is found to be attractive (inward pointing) for $r_0>r_{\rm c}(a)$ and repulsive (outward pointing) for $r_0<r_{\rm c}(a)$, where $a$ is the Kerr spin parameter, $r_0$ is the Boyer-Lindquist orbital radius, and $r_{\rm c}$ is a critical $a$-dependent radius at which the conservative SSF vanishes. When the motion is retrograde the conservative SSF is repulsive for all $r_0$ (as in the Schwarzschild case). The dominant conservative effect of the SSF in Schwarzschild spacetime is known to be of 3rd post-Newtonian (PN) order (with a logarithmic running). Our numerical results suggest that the leading-order PN correction due to the black hole's spin arises from spin-orbit coupling at 3PN, which dominates the overall SSF effect at large $r_0$. In PN language, the change-of-sign of the radial SSF is attributed to an interplay between the spin-orbit term ($\propto -ar_0^{-4.5}$) and the "Schwarzschild" term ($\propto r_0^{-5}\log r_0$). |
gr-qc/9605054 | Daniel Finley | J. D. Finley, III (Univ. of New Mexico), J. F. Pleba\'nski (CINVESTAV
del IPN, Mexico, D. F.), Maciej Przanowski (Technical University, \L\'od\'z,
Poland) | An Iterative Approach to Twisting and Diverging, Type N, Vacuum Einstein
Equations: A (Third-Order) Resolution of Stephani's `Paradox' | 11 pages, a plain TeX file, submitted to ``Classical and Quantum
Gravity'' | Class.Quant.Grav. 14 (1997) 489-498 | 10.1088/0264-9381/14/2/021 | null | gr-qc | null | In 1993, a proof was published, within ``Classical and Quantum Gravity,''
that there are no regular solutions to the {\it linearized} version of the
twisting, type-N, vacuum solutions of the Einstein field equations. While this
proof is certainly correct, we show that the conclusions drawn from that fact
were unwarranted, namely that this irregularity caused such solutions not to be
able to truly describe pure gravitational waves. In this article, we resolve
the paradox---since such first-order solutions must always have singular lines
in space for all sufficiently large values of $r$---by showing that if we
perturbatively iterate the solution up to the third order in small quantities,
there are acceptable regular solutions. That these solutions become flat before
they become non-twisting tells us something interesting concerning the general
behavior of solutions describing gravitational radiation from a bounded source.
| [
{
"created": "Fri, 24 May 1996 23:30:33 GMT",
"version": "v1"
}
] | 2012-08-27 | [
[
"Finley",
"J. D.",
"",
"Univ. of New Mexico"
],
[
"III",
"",
"",
"Univ. of New Mexico"
],
[
"Plebański",
"J. F.",
"",
"CINVESTAV\n del IPN, Mexico, D. F."
],
[
"Przanowski",
"Maciej",
"",
"Technical University, Łódź,\n Poland"
]
] | In 1993, a proof was published, within ``Classical and Quantum Gravity,'' that there are no regular solutions to the {\it linearized} version of the twisting, type-N, vacuum solutions of the Einstein field equations. While this proof is certainly correct, we show that the conclusions drawn from that fact were unwarranted, namely that this irregularity caused such solutions not to be able to truly describe pure gravitational waves. In this article, we resolve the paradox---since such first-order solutions must always have singular lines in space for all sufficiently large values of $r$---by showing that if we perturbatively iterate the solution up to the third order in small quantities, there are acceptable regular solutions. That these solutions become flat before they become non-twisting tells us something interesting concerning the general behavior of solutions describing gravitational radiation from a bounded source. |
1508.02852 | Jun-Qi Guo | Jun-Qi Guo, Pankaj S. Joshi, and Jose T. Galvez Ghersi | Mass inflation and curvature divergence near the central singularity in
spherical collapse | 7 pages, 3 figures. Minor change. Related paper. arXiv:1507.01806 | Phys. Rev. D 92, 104044 (2015) | 10.1103/PhysRevD.92.104044 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study spherical scalar collapse toward a black hole formation and examine
the asymptotic dynamics near the central singularity of the formed black hole.
It is found that, in the vicinity of the singularity, due to the strong
backreaction of a scalar field on the geometry, the mass function inflates and
the Kretschmann scalar grows faster than in the Schwarzschild geometry. In
collapse, the Misner-Sharp mass is a locally conserved quantity, not providing
information on the black hole mass that is measured at asymptotically flat
regions.
| [
{
"created": "Wed, 12 Aug 2015 08:52:22 GMT",
"version": "v1"
},
{
"created": "Sat, 10 Oct 2015 23:49:18 GMT",
"version": "v2"
},
{
"created": "Thu, 26 Nov 2015 07:03:00 GMT",
"version": "v3"
}
] | 2015-11-30 | [
[
"Guo",
"Jun-Qi",
""
],
[
"Joshi",
"Pankaj S.",
""
],
[
"Ghersi",
"Jose T. Galvez",
""
]
] | We study spherical scalar collapse toward a black hole formation and examine the asymptotic dynamics near the central singularity of the formed black hole. It is found that, in the vicinity of the singularity, due to the strong backreaction of a scalar field on the geometry, the mass function inflates and the Kretschmann scalar grows faster than in the Schwarzschild geometry. In collapse, the Misner-Sharp mass is a locally conserved quantity, not providing information on the black hole mass that is measured at asymptotically flat regions. |
gr-qc/9903086 | Kristin Schleich | Kristin Schleich and Donald Witt | Exotic Spaces in Quantum Gravity I: Euclidean Quantum Gravity in Seven
Dimensions | AmsTex, 23 pages 5 eps figures; replaced figures with ones which are
hopefully viewable in pdf format | Class.Quant.Grav. 16 (1999) 2447-2469 | 10.1088/0264-9381/16/7/319 | null | gr-qc | null | It is well known that in four or more dimensions, there exist exotic
manifolds; manifolds that are homeomorphic but not diffeomorphic to each other.
More precisely, exotic manifolds are the same topological manifold but have
inequivalent differentiable structures. This situation is in contrast to the
uniqueness of the differentiable structure on topological manifolds in one, two
and three dimensions. As exotic manifolds are not diffeomorphic, one can argue
that quantum amplitudes for gravity formulated as functional integrals should
include a sum over not only physically distinct geometries and topologies but
also inequivalent differentiable structures. But can the inclusion of exotic
manifolds in such sums make a significant contribution to these quantum
amplitudes? This paper will demonstrate that it will. Simply connected exotic
Einstein manifolds with positive curvature exist in seven dimensions. Their
metrics are found numerically; they are shown to have volumes of the same order
of magnitude. Their contribution to the semiclassical evaluation of the
partition function for Euclidean quantum gravity in seven dimensions is
evaluated and found to be nontrivial. Consequently, inequivalent differentiable
structures should be included in the formulation of sums over histories for
quantum gravity.
| [
{
"created": "Tue, 23 Mar 1999 00:04:47 GMT",
"version": "v1"
},
{
"created": "Fri, 26 Mar 1999 10:23:05 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Schleich",
"Kristin",
""
],
[
"Witt",
"Donald",
""
]
] | It is well known that in four or more dimensions, there exist exotic manifolds; manifolds that are homeomorphic but not diffeomorphic to each other. More precisely, exotic manifolds are the same topological manifold but have inequivalent differentiable structures. This situation is in contrast to the uniqueness of the differentiable structure on topological manifolds in one, two and three dimensions. As exotic manifolds are not diffeomorphic, one can argue that quantum amplitudes for gravity formulated as functional integrals should include a sum over not only physically distinct geometries and topologies but also inequivalent differentiable structures. But can the inclusion of exotic manifolds in such sums make a significant contribution to these quantum amplitudes? This paper will demonstrate that it will. Simply connected exotic Einstein manifolds with positive curvature exist in seven dimensions. Their metrics are found numerically; they are shown to have volumes of the same order of magnitude. Their contribution to the semiclassical evaluation of the partition function for Euclidean quantum gravity in seven dimensions is evaluated and found to be nontrivial. Consequently, inequivalent differentiable structures should be included in the formulation of sums over histories for quantum gravity. |
gr-qc/0505086 | Robert T. Jantzen | Robert T. Jantzen | The densitized lapse ("Taub function") and the Taub time gauge in
cosmology | 22 pages, Latex article style, no figures | Nuovo Cim. B119 (2004) 697-715 | 10.1393/ncb/i2004-10177-7 | null | gr-qc | null | The role of the Taub time gauge in cosmology is linked to the use of the
densitized lapse function instead of the lapse function in the variational
principle approach to the Einstein equations. The spatial metric variational
equations then become the Ricci evolution equations, which are then
supplemented by the Einstein constraints which result from the variation with
respect to the densitized lapse and the usual shift vector field. In those
spatially homogeneous cases where the least disconnect occurs between the
general theory and the restricted symmetry scenario, the recent adjustment of
the conformal approach to solving the initial value problem resulting from
densitized lapse considerations is seen to be inherent in the use of
symmetry-adapted metric variables. The minimal distortion shift vector field is
a natural vector potential for the new York thin sandwich initial data approach
to the constraints, which in this case corresponds to the diagonal spatial
metric gauge. For generic spacetimes, the new approach suggests defining a new
minimal distortion shift gauge which agrees with the old gauge in the Taub time
gauge, but which also makes its defining differential equation agree with the
vector potential equation for solving the supermomentum constraint in any time
gauge.
| [
{
"created": "Wed, 18 May 2005 18:46:50 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Jantzen",
"Robert T.",
""
]
] | The role of the Taub time gauge in cosmology is linked to the use of the densitized lapse function instead of the lapse function in the variational principle approach to the Einstein equations. The spatial metric variational equations then become the Ricci evolution equations, which are then supplemented by the Einstein constraints which result from the variation with respect to the densitized lapse and the usual shift vector field. In those spatially homogeneous cases where the least disconnect occurs between the general theory and the restricted symmetry scenario, the recent adjustment of the conformal approach to solving the initial value problem resulting from densitized lapse considerations is seen to be inherent in the use of symmetry-adapted metric variables. The minimal distortion shift vector field is a natural vector potential for the new York thin sandwich initial data approach to the constraints, which in this case corresponds to the diagonal spatial metric gauge. For generic spacetimes, the new approach suggests defining a new minimal distortion shift gauge which agrees with the old gauge in the Taub time gauge, but which also makes its defining differential equation agree with the vector potential equation for solving the supermomentum constraint in any time gauge. |
gr-qc/0603040 | Guihua Tian | Tian Gui-hua, Shi-kun Wang, Shuquan Zhong | Klein-Gordon equation and the stable problem in the Rindler space-time | 5pages, no figuer | null | null | null | gr-qc | null | The Klein-Gordon equation in the Rindler space-time is studied carefully. It
is shown that the stable properties depend on using what time coordinate to
define the initial time. If we use the Rindler time, the scalar field is
stable. Alternatively, if we use the Minkowski time, the scalar field may be
regarded unstable to some extent. Furthermore, the complete extension of the
Rindler space time is the Minkowski space time, we could also study the stable
problem of the Rindler space time by the Klein-Gordon equation completely in
the Minkowski coordinates system. The results support that the Rindler space
time is really unstable. This in turn might cast some lights on the stable
problem of the Schwarzschild black-hole, which not only in many aspects shares
the similar geometrical properties with the Rindler space time but also has the
very same situation in stable study as that in Rindler space time. So, it is
not unreasonable to infer that the Schwarzschild black hole might really be
unstable in comparison with the case in Rindler space time. Of course, one must
go further to get the conclusion definitely.
| [
{
"created": "Sun, 12 Mar 2006 02:56:34 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Gui-hua",
"Tian",
""
],
[
"Wang",
"Shi-kun",
""
],
[
"Zhong",
"Shuquan",
""
]
] | The Klein-Gordon equation in the Rindler space-time is studied carefully. It is shown that the stable properties depend on using what time coordinate to define the initial time. If we use the Rindler time, the scalar field is stable. Alternatively, if we use the Minkowski time, the scalar field may be regarded unstable to some extent. Furthermore, the complete extension of the Rindler space time is the Minkowski space time, we could also study the stable problem of the Rindler space time by the Klein-Gordon equation completely in the Minkowski coordinates system. The results support that the Rindler space time is really unstable. This in turn might cast some lights on the stable problem of the Schwarzschild black-hole, which not only in many aspects shares the similar geometrical properties with the Rindler space time but also has the very same situation in stable study as that in Rindler space time. So, it is not unreasonable to infer that the Schwarzschild black hole might really be unstable in comparison with the case in Rindler space time. Of course, one must go further to get the conclusion definitely. |
1211.5535 | Ryuichi Fujita | Ryuichi Fujita | Gravitational Waves from a Particle in Circular Orbits around a
Schwarzschild Black Hole to the 22nd Post-Newtonian Order | 22 pages, additional datafiles are available at <a
href="http://www2.yukawa.kyoto-u.ac.jp/~misao/BHPC/calcs.html">this http
URL</a> | Prog. Theor. Phys. 128 (2012) pp. 971-992 | 10.1143/PTP.128.971 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We extend our previous results of the 14th post-Newtonian (PN) order
expansion of gravitational waves for a test particle in circular orbits around
a Schwarzschild black hole to the 22PN order, i.e. $v^{44}$ beyond the leading
Newtonian approximation where $v$ is the orbital velocity of a test particle.
Comparing our 22PN formula for the energy flux with high precision numerical
results, we find that the relative error of the 22PN flux at the innermost
stable circular orbit is about $10^{-5}$. We also estimate the phase difference
between the 22PN waveforms and numerical waveforms after a two-year inspiral.
We find that the dephase is about $10^{-9}$ for $\mu/M=10^{-4}$ and $10^{-2}$
for $\mu/M=10^{-5}$ where $\mu$ is the mass of the compact object and $M$ the
mass of the central supermassive black hole. Finally, we construct a hybrid
formula of the energy flux by supplementing the 4PN formula of the energy flux
for circular and equatorial orbits around a Kerr black hole with all the
present 22PN terms for the case of a Schwarzschild black hole. Comparing the
hybrid formula with the the full numerical results, we examine the performance
of the hybrid formula for the case of Kerr black hole.
| [
{
"created": "Fri, 23 Nov 2012 16:04:44 GMT",
"version": "v1"
}
] | 2012-11-26 | [
[
"Fujita",
"Ryuichi",
""
]
] | We extend our previous results of the 14th post-Newtonian (PN) order expansion of gravitational waves for a test particle in circular orbits around a Schwarzschild black hole to the 22PN order, i.e. $v^{44}$ beyond the leading Newtonian approximation where $v$ is the orbital velocity of a test particle. Comparing our 22PN formula for the energy flux with high precision numerical results, we find that the relative error of the 22PN flux at the innermost stable circular orbit is about $10^{-5}$. We also estimate the phase difference between the 22PN waveforms and numerical waveforms after a two-year inspiral. We find that the dephase is about $10^{-9}$ for $\mu/M=10^{-4}$ and $10^{-2}$ for $\mu/M=10^{-5}$ where $\mu$ is the mass of the compact object and $M$ the mass of the central supermassive black hole. Finally, we construct a hybrid formula of the energy flux by supplementing the 4PN formula of the energy flux for circular and equatorial orbits around a Kerr black hole with all the present 22PN terms for the case of a Schwarzschild black hole. Comparing the hybrid formula with the the full numerical results, we examine the performance of the hybrid formula for the case of Kerr black hole. |
1403.3879 | Tomasz Pawlowski | Tomasz Paw{\l}owski | Geometric time in quantum cosmology | 3 pages, To appear in Proceedings of the 13th Marcel Grossmann
Meeting (MG13), Stockholm, Sweden, 1-7 July 2012 | null | 10.1142/9789814623995_0416 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Various choices of the geometry degrees of freedom as the emergent time are
tested on the model of an isotropic universe with a scalar field of $\phi^2$
potential. Potential problems with each choices as well as possible
applications in loop quantization are discussed.
| [
{
"created": "Sun, 16 Mar 2014 03:50:51 GMT",
"version": "v1"
}
] | 2015-06-19 | [
[
"Pawłowski",
"Tomasz",
""
]
] | Various choices of the geometry degrees of freedom as the emergent time are tested on the model of an isotropic universe with a scalar field of $\phi^2$ potential. Potential problems with each choices as well as possible applications in loop quantization are discussed. |
1711.07597 | Jeremie Szeftel | Sergiu Klainerman, Jeremie Szeftel | Global Nonlinear Stability of Schwarzschild Spacetime under Polarized
Perturbations | 907 pages. The previous version was intended to be the first in a
sequence of three papers. This new version provides a full, comprehensive,
proof of the stability of Schwarzschild. It also revamps considerably the
material presented in the first version and provides a stronger result | null | null | null | gr-qc math-ph math.AP math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We prove the nonlinear stability of the Schwarzschild spacetime under axially
symmetric polarized perturbations, i.e. solutions of the Einstein vacuum
equations for asymptotically flat $1+3$ dimensional Lorentzian metrics which
admit a hypersurface orthogonal spacelike Killing vectorfield with closed
orbits. While building on the remarkable advances made in last 15 years on
establishing quantitative linear stability, the paper introduces a series of
new ideas among which we emphasize the general covariant modulation (GCM)
procedure which allows us to construct, dynamically, the center of mass frame
of the final state. The mass of the final state itself is tracked using the
well known Hawking mass relative to a well adapted foliation itself connected
to the center of mass frame. Our work here is the first to prove the nonlinear
stability of Schwarzschild in a restricted class of nontrivial perturbations.
To a large extent, the restriction to this class of perturbations is only
needed to ensure that the final state of evolution is another Schwarzschild
space. We are thus confident that our procedure may apply in a more general
setting.
| [
{
"created": "Tue, 21 Nov 2017 01:23:42 GMT",
"version": "v1"
},
{
"created": "Thu, 20 Dec 2018 22:41:31 GMT",
"version": "v2"
}
] | 2018-12-24 | [
[
"Klainerman",
"Sergiu",
""
],
[
"Szeftel",
"Jeremie",
""
]
] | We prove the nonlinear stability of the Schwarzschild spacetime under axially symmetric polarized perturbations, i.e. solutions of the Einstein vacuum equations for asymptotically flat $1+3$ dimensional Lorentzian metrics which admit a hypersurface orthogonal spacelike Killing vectorfield with closed orbits. While building on the remarkable advances made in last 15 years on establishing quantitative linear stability, the paper introduces a series of new ideas among which we emphasize the general covariant modulation (GCM) procedure which allows us to construct, dynamically, the center of mass frame of the final state. The mass of the final state itself is tracked using the well known Hawking mass relative to a well adapted foliation itself connected to the center of mass frame. Our work here is the first to prove the nonlinear stability of Schwarzschild in a restricted class of nontrivial perturbations. To a large extent, the restriction to this class of perturbations is only needed to ensure that the final state of evolution is another Schwarzschild space. We are thus confident that our procedure may apply in a more general setting. |
gr-qc/0510040 | Peter D'Eath | A.N.St.J.Farley and P.D.D'Eath | Vaidya Space-Time in Black-Hole Evaporation | null | Gen.Rel.Grav. 38 (2006) 425-443 | 10.1007/s10714-006-0231-3 | null | gr-qc | null | Recently we have studied, using a boundary-value approach, quantum amplitudes
resulting from gravitational collapse to a black hole. Suitable boundary data
for all fields present are posed on initial and final space-like asymptotically
flat hypersurfaces $\Sigma_{I,F}$. The Lorentzian proper-time separation
between the surfaces, as measured at spatial infinity, is denoted by $T$.
Following Feynman's $+i\epsilon$ approach, we rotate $T$ into the complex:
$T\to {\mid}T{\mid} \exp(-i\theta)$, where $0<\theta\leq\pi/2$. The
corresponding {\it classical} complex boundary-value problem is expected to be
well-posed for $\theta > 0$. The Lorentzian amplitude is found by taking the
limit $\theta \to 0_+$ of the quantum amplitude, itself closely approximated by
the semi-classical expression $\exp(iS_{\rm class})$, where $S_{\rm class}$ is
the classical action. For given weak anisotropic spin-0 and spin-2 boundary
data on $\Sigma_F$, one can compute an effective classical energy-momentum
tensor in the interior, which has been averaged over several wave-lengths of
the radiation. This averaged extra contribution will be spherically symmetric,
equivalent to a null fluid, and describing the radial outward streaming of the
radiation (of quantum origin). The corresponding space-time metric, in this
region containing radially-outgoing radiation, is of the Vaidya form. This, in
turn, justifies the treatment of the adiabatic radial mode equations, for spins
$s=0$ and $s=2$, which is used throughout this larger project.
| [
{
"created": "Sat, 8 Oct 2005 16:22:56 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Farley",
"A. N. St. J.",
""
],
[
"D'Eath",
"P. D.",
""
]
] | Recently we have studied, using a boundary-value approach, quantum amplitudes resulting from gravitational collapse to a black hole. Suitable boundary data for all fields present are posed on initial and final space-like asymptotically flat hypersurfaces $\Sigma_{I,F}$. The Lorentzian proper-time separation between the surfaces, as measured at spatial infinity, is denoted by $T$. Following Feynman's $+i\epsilon$ approach, we rotate $T$ into the complex: $T\to {\mid}T{\mid} \exp(-i\theta)$, where $0<\theta\leq\pi/2$. The corresponding {\it classical} complex boundary-value problem is expected to be well-posed for $\theta > 0$. The Lorentzian amplitude is found by taking the limit $\theta \to 0_+$ of the quantum amplitude, itself closely approximated by the semi-classical expression $\exp(iS_{\rm class})$, where $S_{\rm class}$ is the classical action. For given weak anisotropic spin-0 and spin-2 boundary data on $\Sigma_F$, one can compute an effective classical energy-momentum tensor in the interior, which has been averaged over several wave-lengths of the radiation. This averaged extra contribution will be spherically symmetric, equivalent to a null fluid, and describing the radial outward streaming of the radiation (of quantum origin). The corresponding space-time metric, in this region containing radially-outgoing radiation, is of the Vaidya form. This, in turn, justifies the treatment of the adiabatic radial mode equations, for spins $s=0$ and $s=2$, which is used throughout this larger project. |
2010.13310 | Mikhail Shneider | Mikhail N. Shneider, Mikhail Pekker | Cavitation model of the initial stage of Big Bang | null | Physics of Fluids 33, 017116 (2021) | 10.1063/5.0035458 | null | gr-qc physics.flu-dyn | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we propose a model for the initial stage of the development of
the Universe, analogous to cavitation in a liquid in a negative pressure field.
It is assumed that at the stage of inflation, multiple breaks of the metric
occur with the formation of areas of physical vacuum in which the generation of
matter occurs. The proposed model explains the large-scale isotropy of the
Universe without ultrafast inflationary expansion and the emergence of a
large-scale cellular (cluster) structure, as a result of the development of
cavitation ruptures of a false vacuum. It is shown that the cavitation model
can be considered on par with (or as an alternative to) the generally accepted
inflationary multiverse model of the Big Bang.
| [
{
"created": "Mon, 26 Oct 2020 03:36:24 GMT",
"version": "v1"
},
{
"created": "Mon, 2 Nov 2020 23:39:51 GMT",
"version": "v2"
}
] | 2021-02-04 | [
[
"Shneider",
"Mikhail N.",
""
],
[
"Pekker",
"Mikhail",
""
]
] | In this paper, we propose a model for the initial stage of the development of the Universe, analogous to cavitation in a liquid in a negative pressure field. It is assumed that at the stage of inflation, multiple breaks of the metric occur with the formation of areas of physical vacuum in which the generation of matter occurs. The proposed model explains the large-scale isotropy of the Universe without ultrafast inflationary expansion and the emergence of a large-scale cellular (cluster) structure, as a result of the development of cavitation ruptures of a false vacuum. It is shown that the cavitation model can be considered on par with (or as an alternative to) the generally accepted inflationary multiverse model of the Big Bang. |
gr-qc/0110093 | Kechkin O. V. | Oleg V. Kechkin | Generation of heterotic string theory solutions from the stationary
Einstein-Maxwell fields | 16 pages in LATEX | Phys.Lett. B522 (2001) 166-176 | 10.1016/S0370-2693(01)01249-7 | null | gr-qc | null | A new formalism for construction of the stationary solutions is developed for
the four-dimensional gravity coupled to the dilaton, Kalb-Ramond and two
Maxwell fields in a low-energy heterotic string theory form. The result of
generation is automatically invariant in respect to subgroup of the stationary
charging symmetry transformations; the generation can be started from the
stationary Einstein-Maxwell fields. The formalism is given both in real and new
compact complex form, the result of maximal symmetry extension of the
stationary Einstein-Maxwell theory to discussing string gravity model is
explicitly written down.
| [
{
"created": "Tue, 23 Oct 2001 00:58:16 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Kechkin",
"Oleg V.",
""
]
] | A new formalism for construction of the stationary solutions is developed for the four-dimensional gravity coupled to the dilaton, Kalb-Ramond and two Maxwell fields in a low-energy heterotic string theory form. The result of generation is automatically invariant in respect to subgroup of the stationary charging symmetry transformations; the generation can be started from the stationary Einstein-Maxwell fields. The formalism is given both in real and new compact complex form, the result of maximal symmetry extension of the stationary Einstein-Maxwell theory to discussing string gravity model is explicitly written down. |
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