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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1405.4038 | Leandro A. Oliveira | Leandro A. Oliveira, Vitor Cardoso, Lu\'is C. B. Crispino | Ergoregion instability: The hydrodynamic vortex | 10 pages, 8 figures, 2 tables | Phys. Rev. D 89, 124008 (2014) | 10.1103/PhysRevD.89.124008 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Four-dimensional, asymptotically flat spacetimes with an ergoregion but no
horizon have been shown to be linearly unstable against a
superradiant-triggered mechanism. This result has wide implications in the
search for astrophysically viable alternatives to black holes, but also in the
understanding of black holes and Hawking evaporation. Here we investigate this
instability in detail for a particular setup which can be realized in the
laboratory: the {\it hydrodynamic vortex}, an effective geometry for sound
waves, with ergoregion and without an event horizon.
| [
{
"created": "Fri, 16 May 2014 00:24:16 GMT",
"version": "v1"
}
] | 2014-06-10 | [
[
"Oliveira",
"Leandro A.",
""
],
[
"Cardoso",
"Vitor",
""
],
[
"Crispino",
"Luís C. B.",
""
]
] | Four-dimensional, asymptotically flat spacetimes with an ergoregion but no horizon have been shown to be linearly unstable against a superradiant-triggered mechanism. This result has wide implications in the search for astrophysically viable alternatives to black holes, but also in the understanding of black holes and Hawking evaporation. Here we investigate this instability in detail for a particular setup which can be realized in the laboratory: the {\it hydrodynamic vortex}, an effective geometry for sound waves, with ergoregion and without an event horizon. |
1101.1030 | Dinesh Singh | Dinesh Singh, Nader Mobed | Local Space-Time Curvature Effects on Quantum Orbital Angular Momentum | 21 pages, 1 figure; references added; accepted for publication in
Classical and Quantum Gravity | Class.Quant.Grav.28:105024,2011 | 10.1088/0264-9381/28/10/105024 | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper claims that local space-time curvature can non-trivially
contribute to the properties of orbital angular momentum in quantum mechanics.
Of key importance is the demonstration that an extended orbital angular
momentum operator due to gravitation can identify the existence of orbital
states with half-integer projection quantum numbers "m" along the axis of
quantization, while still preserving integer-valued orbital quantum numbers "l"
for a simply connected topology. The consequences of this possibility are
explored in depth, noting that the half-integer "m" states vanish as required
when the locally curved space-time reduces to flat space-time, fully recovering
all established properties of orbital angular momentum in this limit. In
particular, it is shown that a minimum orbital number of "l = 2" is necessary
for the gravitational interaction to appear within this context, in perfect
correspondence with the spin-2 nature of linearized general relativity.
| [
{
"created": "Wed, 5 Jan 2011 17:12:30 GMT",
"version": "v1"
},
{
"created": "Fri, 1 Apr 2011 16:32:30 GMT",
"version": "v2"
}
] | 2011-04-28 | [
[
"Singh",
"Dinesh",
""
],
[
"Mobed",
"Nader",
""
]
] | This paper claims that local space-time curvature can non-trivially contribute to the properties of orbital angular momentum in quantum mechanics. Of key importance is the demonstration that an extended orbital angular momentum operator due to gravitation can identify the existence of orbital states with half-integer projection quantum numbers "m" along the axis of quantization, while still preserving integer-valued orbital quantum numbers "l" for a simply connected topology. The consequences of this possibility are explored in depth, noting that the half-integer "m" states vanish as required when the locally curved space-time reduces to flat space-time, fully recovering all established properties of orbital angular momentum in this limit. In particular, it is shown that a minimum orbital number of "l = 2" is necessary for the gravitational interaction to appear within this context, in perfect correspondence with the spin-2 nature of linearized general relativity. |
1809.01781 | Hyerim Noh | Jai-chan Hwang, Hyerim Noh, Chan-Gyung Park, Da-Hee Lee | Perturbation initial conditions for a couple of dark energy scalar field
potentials | 7 pages, 5 figures | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present perturbation initial conditions for two types of scalar field
potential often used in the dark energy study: one inverse power-law and the
other exponential. The solutions are presented in the presence of the $w =$
constant fluid ($w = 1/3$ for radiation fluid), a minimally coupled scalar
field and a sub-dominating zero-pressure fluid (cold dark matter and baryon
dust). We consider two gauge conditions, the $w$-fluid comoving gauge and the
cold-dark-matter comoving gauge; solutions in the latter gauge are derived by
the gauge transformation and this method can be applied to derive solutions in
any other gauge condition.
| [
{
"created": "Thu, 6 Sep 2018 01:23:13 GMT",
"version": "v1"
}
] | 2018-09-07 | [
[
"Hwang",
"Jai-chan",
""
],
[
"Noh",
"Hyerim",
""
],
[
"Park",
"Chan-Gyung",
""
],
[
"Lee",
"Da-Hee",
""
]
] | We present perturbation initial conditions for two types of scalar field potential often used in the dark energy study: one inverse power-law and the other exponential. The solutions are presented in the presence of the $w =$ constant fluid ($w = 1/3$ for radiation fluid), a minimally coupled scalar field and a sub-dominating zero-pressure fluid (cold dark matter and baryon dust). We consider two gauge conditions, the $w$-fluid comoving gauge and the cold-dark-matter comoving gauge; solutions in the latter gauge are derived by the gauge transformation and this method can be applied to derive solutions in any other gauge condition. |
0812.2811 | J\"org Hennig | J\"org Hennig, Carla Cederbaum, and Marcus Ansorg | A universal inequality for axisymmetric and stationary black holes with
surrounding matter in the Einstein-Maxwell theory | 20 pages | Commun.Math.Phys.293:449-467,2010 | 10.1007/s00220-009-0889-y | null | gr-qc astro-ph math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We prove that in Einstein-Maxwell theory the inequality $(8\pi J)^2+(4\pi
Q^2)^2 < A^2$ holds for any sub-extremal axisymmetric and stationary black hole
with arbitrary surrounding matter. Here $J, Q$, and $A$ are angular momentum,
electric charge, and horizon area of the black hole, respectively.
| [
{
"created": "Mon, 15 Dec 2008 14:17:43 GMT",
"version": "v1"
}
] | 2009-12-04 | [
[
"Hennig",
"Jörg",
""
],
[
"Cederbaum",
"Carla",
""
],
[
"Ansorg",
"Marcus",
""
]
] | We prove that in Einstein-Maxwell theory the inequality $(8\pi J)^2+(4\pi Q^2)^2 < A^2$ holds for any sub-extremal axisymmetric and stationary black hole with arbitrary surrounding matter. Here $J, Q$, and $A$ are angular momentum, electric charge, and horizon area of the black hole, respectively. |
2111.03870 | Mateja Bo\v{s}kovi\'c | Mateja Bo\v{s}kovi\'c, Enrico Barausse | Soliton boson stars, Q-balls and the causal Buchdahl bound | 19+5 pages, 17 figures; v2: minor edits + few references added to
match the published version | JCAP02(2022)032 | 10.1088/1475-7516/2022/02/032 | null | gr-qc astro-ph.CO hep-ph hep-th | http://creativecommons.org/licenses/by/4.0/ | Self-gravitating non-topological solitons whose potential admits multiple
vacua are promising candidates for exotic compact objects. Such objects can
arise in several extensions of the Standard Model and could be produced in the
early Universe. In this work, we focus on objects made from complex scalars
(gravitating Q-balls/soliton boson stars), deriving analytic solutions in
spherical symmetry and comparing them with fully numerical ones. In the
high-compactness limit we find that these objects present an effectively linear
equation of state, thus saturating the Buchdahl limit with the causality
constraint. Far from that limit, these objects behave either as flat space-time
Q-balls or (in the low-compactness limit) as mini boson stars stabilized by
quantum pressure. We establish the robustness of this picture by analyzing a
variety of potentials (including cosine, quartic and sextic ones).
| [
{
"created": "Sat, 6 Nov 2021 12:33:37 GMT",
"version": "v1"
},
{
"created": "Mon, 21 Feb 2022 12:14:52 GMT",
"version": "v2"
}
] | 2022-02-22 | [
[
"Bošković",
"Mateja",
""
],
[
"Barausse",
"Enrico",
""
]
] | Self-gravitating non-topological solitons whose potential admits multiple vacua are promising candidates for exotic compact objects. Such objects can arise in several extensions of the Standard Model and could be produced in the early Universe. In this work, we focus on objects made from complex scalars (gravitating Q-balls/soliton boson stars), deriving analytic solutions in spherical symmetry and comparing them with fully numerical ones. In the high-compactness limit we find that these objects present an effectively linear equation of state, thus saturating the Buchdahl limit with the causality constraint. Far from that limit, these objects behave either as flat space-time Q-balls or (in the low-compactness limit) as mini boson stars stabilized by quantum pressure. We establish the robustness of this picture by analyzing a variety of potentials (including cosine, quartic and sextic ones). |
2404.19216 | Jieci Wang | Qianqian Liu, Tonghua Liu, Cuihong Wen, Jieci Wang | Optimal quantum strategy for locating Unruh channels | 15 pages, 6 figures | null | null | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | From the perspective of quantum information theory, the effect of Unruh
radiation on a two-level accelerated detector can be modeled as a quantum
channel. In this work, we employ the tools of channel-position finding to
locate Unruh channels. The signal-idler and idler-free protocols are explored
to determine the position of the target Unruh channel within a sequence of
background channels. We derive the fidelity-based bounds for the ultimate error
probability of each strategy and obtain the conditions where the signal-idler
protocol is superior to the protocol involving idler-free states. It is found
that the lower bound of the error probability for the signal-idler scheme
exhibits clear advantages in all cases, while the idler-free scheme can only be
implemented when the temperature of the two channels is very close and the
number of initial states is insufficient. Interestingly, it is shown that the
optimal detection protocol relies on the residual correlations shared between
the emitted probe state and the retained idler modes.
| [
{
"created": "Tue, 30 Apr 2024 02:33:37 GMT",
"version": "v1"
}
] | 2024-05-01 | [
[
"Liu",
"Qianqian",
""
],
[
"Liu",
"Tonghua",
""
],
[
"Wen",
"Cuihong",
""
],
[
"Wang",
"Jieci",
""
]
] | From the perspective of quantum information theory, the effect of Unruh radiation on a two-level accelerated detector can be modeled as a quantum channel. In this work, we employ the tools of channel-position finding to locate Unruh channels. The signal-idler and idler-free protocols are explored to determine the position of the target Unruh channel within a sequence of background channels. We derive the fidelity-based bounds for the ultimate error probability of each strategy and obtain the conditions where the signal-idler protocol is superior to the protocol involving idler-free states. It is found that the lower bound of the error probability for the signal-idler scheme exhibits clear advantages in all cases, while the idler-free scheme can only be implemented when the temperature of the two channels is very close and the number of initial states is insufficient. Interestingly, it is shown that the optimal detection protocol relies on the residual correlations shared between the emitted probe state and the retained idler modes. |
1905.00900 | Josu\'e Motoa-Manzano | Juan P. Beltr\'an Almeida, Josu\'e Motoa-Manzano and C\'esar A.
Valenzuela-Toledo | Correlation functions of sourced gravitational waves in inflationary
scalar vector models. A symmetry based approach | Typos corrected, some clarifying comments added and references added.
Matches the published version | JHEP09(2019)118 | 10.1007/JHEP09(2019)118 | PI/UAN-2019-648FT | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We use conformal symmetry to constrain the shape of inflationary correlators
in the presence of long-lived vector field perturbations. Applying conformal
Ward identities, we derive general expressions, up to amplitudes and
normalization factors, for the two and three point correlators in the presence
of vector fields mediated by the interaction $f(\phi)\left(F_{\mu \nu}F^{\mu
\nu}+\alpha\tilde{F}_{\mu \nu}F^{\mu \nu}\right)$, where $f(\phi)$ is a
suitable coupling function between the scalar and the vector field. The
previous interaction allows for isotropy and parity symmetry breaking and is
consistent with super horizon conformal symmetry. As an application of the
conformal field theory techniques followed here, we evaluate the mixed
tensor-scalar $\langle \gamma \zeta \rangle$ and tensor-scalar-scalar $\langle
\gamma \zeta \zeta \rangle$ correlators which are interesting to look for
parity violating effects related with chiral gravitational waves. Finally, we
derive consistency relations for the three point correlators obtained.
| [
{
"created": "Thu, 2 May 2019 16:24:11 GMT",
"version": "v1"
},
{
"created": "Tue, 17 Sep 2019 17:29:29 GMT",
"version": "v2"
}
] | 2019-09-24 | [
[
"Almeida",
"Juan P. Beltrán",
""
],
[
"Motoa-Manzano",
"Josué",
""
],
[
"Valenzuela-Toledo",
"César A.",
""
]
] | We use conformal symmetry to constrain the shape of inflationary correlators in the presence of long-lived vector field perturbations. Applying conformal Ward identities, we derive general expressions, up to amplitudes and normalization factors, for the two and three point correlators in the presence of vector fields mediated by the interaction $f(\phi)\left(F_{\mu \nu}F^{\mu \nu}+\alpha\tilde{F}_{\mu \nu}F^{\mu \nu}\right)$, where $f(\phi)$ is a suitable coupling function between the scalar and the vector field. The previous interaction allows for isotropy and parity symmetry breaking and is consistent with super horizon conformal symmetry. As an application of the conformal field theory techniques followed here, we evaluate the mixed tensor-scalar $\langle \gamma \zeta \rangle$ and tensor-scalar-scalar $\langle \gamma \zeta \zeta \rangle$ correlators which are interesting to look for parity violating effects related with chiral gravitational waves. Finally, we derive consistency relations for the three point correlators obtained. |
gr-qc/9211027 | null | E. Calzetta and C. El Hasi | Chaotic Friedmann-Robertson-Walker Cosmology | 28 pages, 11 figures | Class.Quant.Grav.10:1825-1842,1993 | 10.1088/0264-9381/10/9/022 | GTCRG 92-10 | gr-qc | null | We show that the dynamics of a spatially closed Friedmann - Robertson -
Walker Universe conformally coupled to a real, free, massive scalar field, is
chaotic, for large enough field amplitudes. We do so by proving that this
system is integrable under the adiabatic approximation, but that the
corresponding KAM tori break up when non adiabatic terms are considered. This
finding is confirmed by numerical evaluation of the Lyapunov exponents
associated with the system, among other criteria. Chaos sets strong limitations
to our ability to predict the value of the field at the Big Crunch, from its
given value at the Big Bang. (Figures available on request)
| [
{
"created": "Mon, 23 Nov 1992 18:25:53 GMT",
"version": "v1"
}
] | 2010-04-06 | [
[
"Calzetta",
"E.",
""
],
[
"Hasi",
"C. El",
""
]
] | We show that the dynamics of a spatially closed Friedmann - Robertson - Walker Universe conformally coupled to a real, free, massive scalar field, is chaotic, for large enough field amplitudes. We do so by proving that this system is integrable under the adiabatic approximation, but that the corresponding KAM tori break up when non adiabatic terms are considered. This finding is confirmed by numerical evaluation of the Lyapunov exponents associated with the system, among other criteria. Chaos sets strong limitations to our ability to predict the value of the field at the Big Crunch, from its given value at the Big Bang. (Figures available on request) |
gr-qc/0604012 | Yosef Zlochower | M. Campanelli, C. O. Lousto, Y. Zlochower | Spinning-black-hole binaries: The orbital hang up | 5 pages, 5 figures, revtex4. New version accepted for publication in
Physical Review D Rapid Communications | Phys.Rev.D74:041501,2006 | 10.1103/PhysRevD.74.041501 | null | gr-qc astro-ph | null | We present the first fully-nonlinear numerical study of the dynamics of
highly spinning black-hole binaries. We evolve binaries from quasicircular
orbits (as inferred from Post-Newtonian theory), and find that the last stages
of the orbital motion of black-hole binaries are profoundly affected by their
individual spins. In order to cleanly display its effects, we consider two
equal mass holes with individual spin parameters S/m^2=0.757, both aligned and
anti-aligned with the orbital angular momentum (and compare with the spinless
case), and with an initial orbital period of 125M. We find that the aligned
case completes three orbits and merges significantly after the anti-aligned
case, which completes less than one orbit. The total energy radiated for the
former case is ~7% while for the latter it is only ~2%. The final Kerr hole
remnants have rotation parameters a/M=0.89 and a/M=0.44 respectively, showing
the unlikeliness of creating a maximally rotating black hole out of the merger
of two spinning holes.
| [
{
"created": "Tue, 4 Apr 2006 18:19:20 GMT",
"version": "v1"
},
{
"created": "Fri, 28 Jul 2006 20:11:23 GMT",
"version": "v2"
}
] | 2010-04-06 | [
[
"Campanelli",
"M.",
""
],
[
"Lousto",
"C. O.",
""
],
[
"Zlochower",
"Y.",
""
]
] | We present the first fully-nonlinear numerical study of the dynamics of highly spinning black-hole binaries. We evolve binaries from quasicircular orbits (as inferred from Post-Newtonian theory), and find that the last stages of the orbital motion of black-hole binaries are profoundly affected by their individual spins. In order to cleanly display its effects, we consider two equal mass holes with individual spin parameters S/m^2=0.757, both aligned and anti-aligned with the orbital angular momentum (and compare with the spinless case), and with an initial orbital period of 125M. We find that the aligned case completes three orbits and merges significantly after the anti-aligned case, which completes less than one orbit. The total energy radiated for the former case is ~7% while for the latter it is only ~2%. The final Kerr hole remnants have rotation parameters a/M=0.89 and a/M=0.44 respectively, showing the unlikeliness of creating a maximally rotating black hole out of the merger of two spinning holes. |
1707.06101 | Neil J. Cornish | Neil Cornish, Diego Blas and Germano Nardini | Bounding the speed of gravity with gravitational wave observations | Version published in PRL. 5 pages, 3 figures | Phys. Rev. Lett. 119, 161102 (2017) | 10.1103/PhysRevLett.119.161102 | CERN-TH-2017-140 | gr-qc hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The time delay between gravitational wave signals arriving at widely
separated detectors can be used to place upper and lower bounds on the speed of
gravitational wave propagation. Using a Bayesian approach that combines the
first three gravitational wave detections reported by the LIGO collaboration we
constrain the gravitational waves propagation speed c_gw to the 90% credible
interval 0.55 c < c_gw < 1.42 c, where c is the speed of light in vacuum. These
bounds will improve as more detections are made and as more detectors join the
worldwide network. Of order twenty detections by the two LIGO detectors will
constrain the speed of gravity to within 20% of the speed of light, while just
five detections by the LIGO-Virgo-Kagra network will constrain the speed of
gravity to within 1% of the speed of light.
| [
{
"created": "Wed, 19 Jul 2017 14:01:37 GMT",
"version": "v1"
},
{
"created": "Thu, 5 Oct 2017 17:45:30 GMT",
"version": "v2"
}
] | 2017-10-25 | [
[
"Cornish",
"Neil",
""
],
[
"Blas",
"Diego",
""
],
[
"Nardini",
"Germano",
""
]
] | The time delay between gravitational wave signals arriving at widely separated detectors can be used to place upper and lower bounds on the speed of gravitational wave propagation. Using a Bayesian approach that combines the first three gravitational wave detections reported by the LIGO collaboration we constrain the gravitational waves propagation speed c_gw to the 90% credible interval 0.55 c < c_gw < 1.42 c, where c is the speed of light in vacuum. These bounds will improve as more detections are made and as more detectors join the worldwide network. Of order twenty detections by the two LIGO detectors will constrain the speed of gravity to within 20% of the speed of light, while just five detections by the LIGO-Virgo-Kagra network will constrain the speed of gravity to within 1% of the speed of light. |
1709.06450 | Allan Alinea | Allan L. Alinea, Takahiro Kubota | Adiabatic regularization of power spectrum in nonminimally coupled
general single-field inflation | version 3.0, edited Section I on emergence of adiabatic
regularization of power spectrum and Section III on scale invariance,
corrected minor errors in some equations | Phys. Rev. D 97, 063513 (2018) | 10.1103/PhysRevD.97.063513 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We perform adiabatic regularization of power spectrum in nonminimally coupled
general single-field inflation with varying speed of sound. The subtraction is
performed within the framework of earlier study by Urakawa and Starobinsky
dealing with the canonical inflation. Inspired by Fakir and Unruh's model on
nonminimally coupled chaotic inflation, we find upon imposing near
scale-invariant condition, that the subtraction term exponentially decays with
the number of $ e $-folds. As in the result for the canonical inflation, the
regularized power spectrum tends to the "bare" power spectrum as the Universe
expands during (and even after) inflation. This work justifies the use of the
"bare" power spectrum in standard calculation in the most general context of
slow-roll single-field inflation involving non-minimal coupling and varying
speed of sound.
| [
{
"created": "Mon, 18 Sep 2017 12:39:08 GMT",
"version": "v1"
},
{
"created": "Mon, 25 Sep 2017 15:13:44 GMT",
"version": "v2"
},
{
"created": "Tue, 26 Dec 2017 07:23:55 GMT",
"version": "v3"
}
] | 2018-03-15 | [
[
"Alinea",
"Allan L.",
""
],
[
"Kubota",
"Takahiro",
""
]
] | We perform adiabatic regularization of power spectrum in nonminimally coupled general single-field inflation with varying speed of sound. The subtraction is performed within the framework of earlier study by Urakawa and Starobinsky dealing with the canonical inflation. Inspired by Fakir and Unruh's model on nonminimally coupled chaotic inflation, we find upon imposing near scale-invariant condition, that the subtraction term exponentially decays with the number of $ e $-folds. As in the result for the canonical inflation, the regularized power spectrum tends to the "bare" power spectrum as the Universe expands during (and even after) inflation. This work justifies the use of the "bare" power spectrum in standard calculation in the most general context of slow-roll single-field inflation involving non-minimal coupling and varying speed of sound. |
2005.10991 | Angel Rincon | Angel Rincon, Ernesto Contreras, Francisco Tello-Ortiz, Pedro
Bargue\~no and Gabriel Abell\'an | Anisotropic 2+1 dimensional black holes by gravitational decoupling | 8 pages, 3 figures, accepted for publication in EPJ C | null | 10.1140/epjc/s10052-020-8071-y | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the present paper, we analyze the well-known 2+1 dimensional black holes
(assuming a non-vanishing cosmological constant) in light of the gravitational
decoupling by the minimal geometric deformation approach. To illustrate our
results, we consider the BTZ geometry as the seed solution to generate new
anisotropic ones. To complement the study, the curvature scalars and the energy
conditions are analyzed.
| [
{
"created": "Fri, 22 May 2020 03:57:15 GMT",
"version": "v1"
}
] | 2020-06-24 | [
[
"Rincon",
"Angel",
""
],
[
"Contreras",
"Ernesto",
""
],
[
"Tello-Ortiz",
"Francisco",
""
],
[
"Bargueño",
"Pedro",
""
],
[
"Abellán",
"Gabriel",
""
]
] | In the present paper, we analyze the well-known 2+1 dimensional black holes (assuming a non-vanishing cosmological constant) in light of the gravitational decoupling by the minimal geometric deformation approach. To illustrate our results, we consider the BTZ geometry as the seed solution to generate new anisotropic ones. To complement the study, the curvature scalars and the energy conditions are analyzed. |
1008.2679 | Muhammad Sharif | M. Sharif and Sundas Fatima | Charged Cylindrical Collapse of Anisotropic Fluid | 19 pages, accepted for publication in Gen. Relativ. Grav | Gen.Rel.Grav.43:127-142,2011 | 10.1007/s10714-010-1076-3 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Following the scheme developed by Misner and Sharp, we discuss the dynamics
of gravitational collapse. For this purpose, an interior cylindrically
symmetric spacetime is matched to an exterior charged static cylindrically
symmetric spacetime using the Darmois matching conditions. Dynamical equations
are obtained with matter dissipating in the form of shear viscosity. The effect
of charge and dissipative quantities over the cylindrical collapse are studied.
Finally, we show that homogeneity in energy density and conformal flatness of
spacetime are necessary and sufficient for each other.
| [
{
"created": "Fri, 13 Aug 2010 04:22:58 GMT",
"version": "v1"
}
] | 2011-02-11 | [
[
"Sharif",
"M.",
""
],
[
"Fatima",
"Sundas",
""
]
] | Following the scheme developed by Misner and Sharp, we discuss the dynamics of gravitational collapse. For this purpose, an interior cylindrically symmetric spacetime is matched to an exterior charged static cylindrically symmetric spacetime using the Darmois matching conditions. Dynamical equations are obtained with matter dissipating in the form of shear viscosity. The effect of charge and dissipative quantities over the cylindrical collapse are studied. Finally, we show that homogeneity in energy density and conformal flatness of spacetime are necessary and sufficient for each other. |
gr-qc/9809030 | Roh Suan Tung | R. S. Tung (Lancaster University) and J. M. Nester (National Central
University) | The quadratic spinor Lagrangian is equivalent to the teleparallel theory | 10 pages, RevTeX | Phys.Rev.D60:021501,1999 | 10.1103/PhysRevD.60.021501 | null | gr-qc | null | The quadratic spinor Lagrangian is shown to be equivalent to the teleparallel
/ tetrad representation of Einstein's theory. An important consequence is that
the energy-momentum density obtained from this quadratic spinor Lagrangian is
essentially the same as the ``tensor'' proposed by Moller in 1961.
| [
{
"created": "Mon, 7 Sep 1998 20:43:40 GMT",
"version": "v1"
},
{
"created": "Wed, 24 Mar 1999 19:50:30 GMT",
"version": "v2"
}
] | 2009-12-30 | [
[
"Tung",
"R. S.",
"",
"Lancaster University"
],
[
"Nester",
"J. M.",
"",
"National Central\n University"
]
] | The quadratic spinor Lagrangian is shown to be equivalent to the teleparallel / tetrad representation of Einstein's theory. An important consequence is that the energy-momentum density obtained from this quadratic spinor Lagrangian is essentially the same as the ``tensor'' proposed by Moller in 1961. |
gr-qc/0201043 | Pavel Klepac | P. Klepac | On spacetimes with 3-parameter isometry group in string-inspired theory
of gravity | 9 pages, LaTeX 2e | null | null | null | gr-qc | null | Cylindrically symmetric stationary spacetimes are examined in the framework
of string-inpired generalized theory of gravity. In four dimensions this theory
contains a dilatonic scalar field in addition to gravity. A charged perfect
fluid representing fermionic matter is also considered. Explicit solution is
given and a discussion of the geometrical properties of the solutions found is
carried out.
| [
{
"created": "Sun, 13 Jan 2002 11:56:24 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Klepac",
"P.",
""
]
] | Cylindrically symmetric stationary spacetimes are examined in the framework of string-inpired generalized theory of gravity. In four dimensions this theory contains a dilatonic scalar field in addition to gravity. A charged perfect fluid representing fermionic matter is also considered. Explicit solution is given and a discussion of the geometrical properties of the solutions found is carried out. |
gr-qc/0011036 | Robert Beig | R. Beig, M. Karadi | On unbounded bodies with finite mass: asymptotic behaviour | 6 pages | Class.Quant.Grav. 18 (2001) 671-676 | 10.1088/0264-9381/18/4/307 | UWThPh-2000-35 | gr-qc | null | There is introduced a class of barotropic equations of state (EOS) which
become polytropic of index $n = 5$ at low pressure. One then studies
asymptotically flat solutions of the static Einstein equations coupled to
perfect fluids having such an EOS. It is shown that such solutions, in the same
manner as the vacuum ones, are conformally smooth or analytic at infinity, when
the EOS is smooth or analytic, respectively.
| [
{
"created": "Fri, 10 Nov 2000 15:12:26 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Beig",
"R.",
""
],
[
"Karadi",
"M.",
""
]
] | There is introduced a class of barotropic equations of state (EOS) which become polytropic of index $n = 5$ at low pressure. One then studies asymptotically flat solutions of the static Einstein equations coupled to perfect fluids having such an EOS. It is shown that such solutions, in the same manner as the vacuum ones, are conformally smooth or analytic at infinity, when the EOS is smooth or analytic, respectively. |
0901.0302 | Drew Keppel | LIGO Scientific Collaboration: B. Abbott, et al | Search for Gravitational Waves from Low Mass Binary Coalescences in the
First Year of LIGO's S5 Data | 15 pages, 5 figures, 2 tables; changes associated with referee
comments, inclusion of recent LIGO calibration data, fixing small error in
upper limit calculation | Phys.Rev.D79:122001,2009 | 10.1103/PhysRevD.79.122001 | LIGO-P080095-v4 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We have searched for gravitational waves from coalescing low mass compact
binary systems with a total mass between 2 and 35 Msun and a minimum component
mass of 1 Msun using data from the first year of the fifth science run (S5) of
the three LIGO detectors, operating at design sensitivity. Depending on mass,
we are sensitive to coalescences as far as 150 Mpc from the Earth. No
gravitational wave signals were observed above the expected background.
Assuming a compact binary objects population with a Gaussian mass distribution
representing binary neutron star systems, black hole-neutron star binary
systems, and binary black hole systems, we calculate the 90%-confidence upper
limit on the rate of coalescences to be 3.9 \times 10^{-2} yr^{-1} L_{10}^{-1},
1.1 \times 10^{-2} yr^{-1} L_{10}^{-1}, and 2.5 \times 10^{-3} yr^{-1}
L_{10}^{-1} respectively, where $L_{10}$ is $10^{10}$ times the blue solar
luminosity. We also set improved upper limits on the rate of compact binary
coalescences per unit blue-light luminosity, as a function of mass.
| [
{
"created": "Mon, 5 Jan 2009 14:11:38 GMT",
"version": "v1"
},
{
"created": "Thu, 12 Feb 2009 19:57:20 GMT",
"version": "v2"
},
{
"created": "Sun, 15 Mar 2009 21:29:01 GMT",
"version": "v3"
},
{
"created": "Wed, 6 May 2009 23:10:02 GMT",
"version": "v4"
}
] | 2009-06-30 | [
[
"LIGO Scientific Collaboration",
"",
""
],
[
"Abbott",
"B.",
""
]
] | We have searched for gravitational waves from coalescing low mass compact binary systems with a total mass between 2 and 35 Msun and a minimum component mass of 1 Msun using data from the first year of the fifth science run (S5) of the three LIGO detectors, operating at design sensitivity. Depending on mass, we are sensitive to coalescences as far as 150 Mpc from the Earth. No gravitational wave signals were observed above the expected background. Assuming a compact binary objects population with a Gaussian mass distribution representing binary neutron star systems, black hole-neutron star binary systems, and binary black hole systems, we calculate the 90%-confidence upper limit on the rate of coalescences to be 3.9 \times 10^{-2} yr^{-1} L_{10}^{-1}, 1.1 \times 10^{-2} yr^{-1} L_{10}^{-1}, and 2.5 \times 10^{-3} yr^{-1} L_{10}^{-1} respectively, where $L_{10}$ is $10^{10}$ times the blue solar luminosity. We also set improved upper limits on the rate of compact binary coalescences per unit blue-light luminosity, as a function of mass. |
gr-qc/0607045 | Barry Holstein | Barry R. Holstein | Graviton Physics | 25 page latex file, to be publshed in the American Journal of Physics | Am.J.Phys. 74 (2006) 1002-1011 | 10.1119/1.2338547 | null | gr-qc hep-ph | null | The interactions of gravitons with matter are calculated in parallel with the
familiar photon case. It is shown that graviton scattering amplitudes can be
factorized into a product of familiar electromagnetic forms, and cross sections
for various reactions are straightforwardly evaluated using helicity methods.
| [
{
"created": "Tue, 11 Jul 2006 15:40:23 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Holstein",
"Barry R.",
""
]
] | The interactions of gravitons with matter are calculated in parallel with the familiar photon case. It is shown that graviton scattering amplitudes can be factorized into a product of familiar electromagnetic forms, and cross sections for various reactions are straightforwardly evaluated using helicity methods. |
2203.10628 | Douglas A. Singleton | Michael Bishop, Joey Contreras, and Douglas Singleton | A Subtle Aspect of Minimal Lengths in the Generalized Uncertainty
Principle | 14 pages, 3 figures. Published in Universe | Universe 2022, 8(3), 192 | 10.3390/universe8030192 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we point out an overlooked and subtle feature of the
generalized uncertainty principle (GUP) approach to quantizing gravity: namely
that different pairs of modified operators with the same modified commutator,
$[\hat{X},\hat{P}] = i \hbar (1+\beta p^2)$, may have different physical
consequences such as having no minimal length at all. These differences depend
on how the position and/or momentum operators are modified rather than only on
the resulting modified commutator. This provides guidance when constructing GUP
models since it distinguishes those GUPs that have a minimal length scale, as
suggested by some broad arguments about quantum gravity, versus GUPs without a
minimal length scale.
| [
{
"created": "Sun, 20 Mar 2022 19:02:02 GMT",
"version": "v1"
}
] | 2022-03-22 | [
[
"Bishop",
"Michael",
""
],
[
"Contreras",
"Joey",
""
],
[
"Singleton",
"Douglas",
""
]
] | In this work, we point out an overlooked and subtle feature of the generalized uncertainty principle (GUP) approach to quantizing gravity: namely that different pairs of modified operators with the same modified commutator, $[\hat{X},\hat{P}] = i \hbar (1+\beta p^2)$, may have different physical consequences such as having no minimal length at all. These differences depend on how the position and/or momentum operators are modified rather than only on the resulting modified commutator. This provides guidance when constructing GUP models since it distinguishes those GUPs that have a minimal length scale, as suggested by some broad arguments about quantum gravity, versus GUPs without a minimal length scale. |
1602.01266 | Elena Kopteva | Pavlina Jaluvkova, Elena Kopteva, Zdenek Stuchlik | The model of the black hole enclosed in dust. The flat space case | 9 pages, 4 figures | General Relativity and Gravitation, Volume 49, Issue 6, article
id.80, 9 pp. 2017 | 10.1007/s10714-017-2243-6 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work the model is constructed to describe the black hole enclosed in
the dust cosmological background in case of zero spatial curvature. This model
is based on our exact solution of the class of LTB inhomogeneous solutions. We
considered the properties of the model and built the R-T-structure of the
resulting space-time. It was shown that central region includes the
Schwarzchild-like black hole. We derived the equations of motion of the test
particle from the point of view of the observer comoving with cosmological
expansion. We found analytical expressions for observable orbital and radial
velocities of the particle and plotted the surface profile of the total
velocity in this case. In comoving coordinate frame it is impossible to study
the questions concerning the black hole horizon but one can observe the local
motion of the particles influenced by the cosmological expansion.
| [
{
"created": "Wed, 3 Feb 2016 11:07:35 GMT",
"version": "v1"
},
{
"created": "Fri, 19 Feb 2016 18:16:54 GMT",
"version": "v2"
},
{
"created": "Tue, 14 Jun 2016 14:13:41 GMT",
"version": "v3"
},
{
"created": "Wed, 27 Jul 2016 10:11:08 GMT",
"version": "v4"
},
{
"cr... | 2017-11-29 | [
[
"Jaluvkova",
"Pavlina",
""
],
[
"Kopteva",
"Elena",
""
],
[
"Stuchlik",
"Zdenek",
""
]
] | In this work the model is constructed to describe the black hole enclosed in the dust cosmological background in case of zero spatial curvature. This model is based on our exact solution of the class of LTB inhomogeneous solutions. We considered the properties of the model and built the R-T-structure of the resulting space-time. It was shown that central region includes the Schwarzchild-like black hole. We derived the equations of motion of the test particle from the point of view of the observer comoving with cosmological expansion. We found analytical expressions for observable orbital and radial velocities of the particle and plotted the surface profile of the total velocity in this case. In comoving coordinate frame it is impossible to study the questions concerning the black hole horizon but one can observe the local motion of the particles influenced by the cosmological expansion. |
2007.12471 | Kazuharu Bamba | Riasat Ali, Kazuharu Bamba, Muhammad Asgher, M.F. Malik and Syed Asif
Ali Shah | Stability Analysis of Charged Rotating Black Ring | 7 pages, 2 figures, version accepted for publication in Symmetry | Symmetry 12 (2020), 1165 | 10.3390/sym12071165 | FU-PCG-79 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the electromagnetic field equation along with the WKB approximation.
The boson tunneling phenomenon from charged rotating black ring(CRBR) is
analyzed. It is examined that reserve radiation consistent with CRBR can be
computed in general by neglecting back reaction and self-gravitational of the
radiated boson particle. The calculated temperature depends upon quantum
gravity and CRBR geometry. We also examine the corrected tunneling
rate/probability of boson particles by assuming charge as well as energy
conservation laws and the quantum gravity. Furthermore, we study the graphical
behavior of the temperature and check the stability and instability of CRBR.
| [
{
"created": "Wed, 22 Jul 2020 13:19:51 GMT",
"version": "v1"
}
] | 2020-07-27 | [
[
"Ali",
"Riasat",
""
],
[
"Bamba",
"Kazuharu",
""
],
[
"Asgher",
"Muhammad",
""
],
[
"Malik",
"M. F.",
""
],
[
"Shah",
"Syed Asif Ali",
""
]
] | We study the electromagnetic field equation along with the WKB approximation. The boson tunneling phenomenon from charged rotating black ring(CRBR) is analyzed. It is examined that reserve radiation consistent with CRBR can be computed in general by neglecting back reaction and self-gravitational of the radiated boson particle. The calculated temperature depends upon quantum gravity and CRBR geometry. We also examine the corrected tunneling rate/probability of boson particles by assuming charge as well as energy conservation laws and the quantum gravity. Furthermore, we study the graphical behavior of the temperature and check the stability and instability of CRBR. |
1108.5886 | Heeseung Zoe | Sungwook E. Hong, Young Jae Lee and Heeseung Zoe | The Possibility of Inflation in Asymptotically Safe Gravity | 14 pages, 4 figures | Int. J. Mod. Phys. D 21, 1250062 (2012) | 10.1142/S0218271812500629 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We examine the inflationary modes in the cubic curvature theories in the
context of asymptotically safe gravity. On the phase space of the Hubble
parameter, there exists a critical point which corresponds to the slow-roll
inflation in Einstein frame. Most of the e-foldings are attained around the
critical point for each inflationary trajectories. If the coupling constants
$g_i$ have the parametric relations generated as the power of the relative
energy scale of inflation $H_0$ to the ultraviolet cutoff $\Lambda$, a
successful inflation with more than 60 e-foldings occurs near the critical
point.
| [
{
"created": "Tue, 30 Aug 2011 09:16:09 GMT",
"version": "v1"
},
{
"created": "Wed, 15 Feb 2012 14:01:04 GMT",
"version": "v2"
},
{
"created": "Wed, 13 Jun 2012 03:29:14 GMT",
"version": "v3"
}
] | 2012-08-09 | [
[
"Hong",
"Sungwook E.",
""
],
[
"Lee",
"Young Jae",
""
],
[
"Zoe",
"Heeseung",
""
]
] | We examine the inflationary modes in the cubic curvature theories in the context of asymptotically safe gravity. On the phase space of the Hubble parameter, there exists a critical point which corresponds to the slow-roll inflation in Einstein frame. Most of the e-foldings are attained around the critical point for each inflationary trajectories. If the coupling constants $g_i$ have the parametric relations generated as the power of the relative energy scale of inflation $H_0$ to the ultraviolet cutoff $\Lambda$, a successful inflation with more than 60 e-foldings occurs near the critical point. |
0802.3263 | Mustapha Azreg-A\"inou | Mustapha Azreg-A\"inou | Quadratic superconducting cosmic strings revisited | 6 pages | Europhys.Lett.81:60003,2008 | 10.1209/0295-5075/81/60003 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It has been shown that 5-dimensional general relativity action extended by
appropriate quadratic terms admits a singular superconducting cosmic string
solution. We search for cosmic strings endowed with similar and extended
physical properties by directly integrating the non-linear matrix field
equations thus avoiding the perturbative approach by which we constructed the
above-mentioned \textsl{exact} solution. The most general superconducting
cosmic string, subject to some constraints, will be derived and shown to be
mathematically \textsl{unique} up to linear coordinate transformations mixing
its Killing vectors. The most general solution, however, is not globally
equivalent to the old one due to the existence of Killing vectors with closed
orbits.
| [
{
"created": "Fri, 22 Feb 2008 07:20:53 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Azreg-Aïnou",
"Mustapha",
""
]
] | It has been shown that 5-dimensional general relativity action extended by appropriate quadratic terms admits a singular superconducting cosmic string solution. We search for cosmic strings endowed with similar and extended physical properties by directly integrating the non-linear matrix field equations thus avoiding the perturbative approach by which we constructed the above-mentioned \textsl{exact} solution. The most general superconducting cosmic string, subject to some constraints, will be derived and shown to be mathematically \textsl{unique} up to linear coordinate transformations mixing its Killing vectors. The most general solution, however, is not globally equivalent to the old one due to the existence of Killing vectors with closed orbits. |
gr-qc/9406025 | Jerzy Lewandowski | Jerzy Lewandowski | Topological Measure and Graph-Differential Geometry on the Quotient
Space of Connections | 3 pp., Proceedings of ``Journees Relativistes 1993'' | Int.J.Mod.Phys.D3:207-210,1994 | 10.1142/S0218271894000307 | null | gr-qc | null | (This is a report for the Proceedings of ``Journees Relativistes 1993''
written in September 1993. Containes a short description of the results
published elsewhere in the joint paper with A. Ashtekar) Integral calculus on
the space of gauge equivalent connections is developed. By carring out a
non-linear generalization of the theory of cylindrical measures on topological
vector spaces, a faithfull, diffeomorphism invariant measure is introduced on a
suitable completion of the quotient space. The strip (i.e. momentum) operators
are densely-defined in the resulting Hilbert space and interact with the
measure correctly, to become essentially self adjoint operators.
| [
{
"created": "Thu, 16 Jun 1994 13:47:17 GMT",
"version": "v1"
}
] | 2011-04-15 | [
[
"Lewandowski",
"Jerzy",
""
]
] | (This is a report for the Proceedings of ``Journees Relativistes 1993'' written in September 1993. Containes a short description of the results published elsewhere in the joint paper with A. Ashtekar) Integral calculus on the space of gauge equivalent connections is developed. By carring out a non-linear generalization of the theory of cylindrical measures on topological vector spaces, a faithfull, diffeomorphism invariant measure is introduced on a suitable completion of the quotient space. The strip (i.e. momentum) operators are densely-defined in the resulting Hilbert space and interact with the measure correctly, to become essentially self adjoint operators. |
1008.2001 | Carlos O. Lousto | Gabriela Jaramillo and Carlos O. Lousto | Study of multi black hole and ring singularity apparent horizons | 31 pages, 21 figures | null | 10.1103/PhysRevD.84.104011 | null | gr-qc astro-ph.CO astro-ph.GA astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study critical black hole separations for the formation of a common
apparent horizon in systems of $N$ - black holes in a time symmetric
configuration. We study in detail the aligned equal mass cases for $N=2,3,4,5$,
and relate them to the unequal mass binary black hole case. We then study the
apparent horizon of the time symmetric initial geometry of a ring singularity
of different radii. The apparent horizon is used as indicative of the location
of the event horizon in an effort to predict a critical ring radius that would
generate an event horizon of toroidal topology. We found that a good estimate
for this ring critical radius is $20/(3\pi) M$. We briefly discuss the
connection of this two cases through a discrete black hole 'necklace'
configuration.
| [
{
"created": "Wed, 11 Aug 2010 20:31:58 GMT",
"version": "v1"
}
] | 2015-05-19 | [
[
"Jaramillo",
"Gabriela",
""
],
[
"Lousto",
"Carlos O.",
""
]
] | We study critical black hole separations for the formation of a common apparent horizon in systems of $N$ - black holes in a time symmetric configuration. We study in detail the aligned equal mass cases for $N=2,3,4,5$, and relate them to the unequal mass binary black hole case. We then study the apparent horizon of the time symmetric initial geometry of a ring singularity of different radii. The apparent horizon is used as indicative of the location of the event horizon in an effort to predict a critical ring radius that would generate an event horizon of toroidal topology. We found that a good estimate for this ring critical radius is $20/(3\pi) M$. We briefly discuss the connection of this two cases through a discrete black hole 'necklace' configuration. |
2212.06883 | Bivudutta Mishra Dr. | Francisco Tello-Ortiz, B.Mishra, A. Alvarez, Ksh. Newton Singh | Minimally deformed wormholes inspired by noncommutative geometry | 20 pages, 6 figures. Accepted Version Fortschritte der physik | Fortschr. Phys.,71, 2200108, 2023 | 10.1002/prop.202200108 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this article, new wormhole solutions in the framework of General
Relativity are presented. Taking advantage of gravitational decoupling by means
of minimal geometric deformation approach and, the so-called noncommutative
geometry Gaussian and Lorentzian density profiles, the seminal Morris-Thorne
space-time is minimally deformed providing new asymptotically wormhole
solutions. Constraining the signature of some parameters, the dimensionless
constant $\alpha$ is bounded using the flare-out and energy conditions. In both
cases, this results in an energy-momentum tensor that violates energy
conditions, thus the space-time is threading by exotic matter. However, it is
possible to obtain a positive defined density at the wormhole throat and its
neighborhood. To further support the study a thoroughly graphical analysis has
been performed.
| [
{
"created": "Wed, 7 Dec 2022 09:50:12 GMT",
"version": "v1"
}
] | 2023-06-02 | [
[
"Tello-Ortiz",
"Francisco",
""
],
[
"Mishra",
"B.",
""
],
[
"Alvarez",
"A.",
""
],
[
"Singh",
"Ksh. Newton",
""
]
] | In this article, new wormhole solutions in the framework of General Relativity are presented. Taking advantage of gravitational decoupling by means of minimal geometric deformation approach and, the so-called noncommutative geometry Gaussian and Lorentzian density profiles, the seminal Morris-Thorne space-time is minimally deformed providing new asymptotically wormhole solutions. Constraining the signature of some parameters, the dimensionless constant $\alpha$ is bounded using the flare-out and energy conditions. In both cases, this results in an energy-momentum tensor that violates energy conditions, thus the space-time is threading by exotic matter. However, it is possible to obtain a positive defined density at the wormhole throat and its neighborhood. To further support the study a thoroughly graphical analysis has been performed. |
gr-qc/9603037 | Julio Cesar Fabris | Kirill A. Bronnikov and Julio C. Fabris (Universidade Federal do
Espirito Santo - Vitoria - Espirito Santo - Brazil) | Ring Wormholes in D-Dimensional Einstein and Dilaton Gravity | Latex file, 15 pages | null | 10.1088/0264-9381/14/4/003 | DF-UFES/96 | gr-qc | null | On the basis of exact solutions to the Einstein-Abelian gauge-dilaton
equations in $D$-dimensional gravity, the properties of static axial
configurations are discussed. Solutions free of curvature singularities are
selected; they can be attributed to traversible wormholes with cosmic
string-like singularities at their necks. In the presence of an electromagnetic
field some of these wormholes are globally regular, the string-like singularity
being replaced by a set of twofold branching points. Consequences of wormhole
regularity and symmetry conditions are discussed. In particular, it is shown
that (i) regular, symmetric wormholes have necessarily positive masses as
viewed from both asymptotics and (ii) their characteristic length scale in the
big charge limit ($GM^2 \ll Q^2$) is of the order of the ``classical radius"
$Q^2/M$.
| [
{
"created": "Fri, 22 Mar 1996 19:25:01 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Bronnikov",
"Kirill A.",
"",
"Universidade Federal do\n Espirito Santo - Vitoria - Espirito Santo - Brazil"
],
[
"Fabris",
"Julio C.",
"",
"Universidade Federal do\n Espirito Santo - Vitoria - Espirito Santo - Brazil"
]
] | On the basis of exact solutions to the Einstein-Abelian gauge-dilaton equations in $D$-dimensional gravity, the properties of static axial configurations are discussed. Solutions free of curvature singularities are selected; they can be attributed to traversible wormholes with cosmic string-like singularities at their necks. In the presence of an electromagnetic field some of these wormholes are globally regular, the string-like singularity being replaced by a set of twofold branching points. Consequences of wormhole regularity and symmetry conditions are discussed. In particular, it is shown that (i) regular, symmetric wormholes have necessarily positive masses as viewed from both asymptotics and (ii) their characteristic length scale in the big charge limit ($GM^2 \ll Q^2$) is of the order of the ``classical radius" $Q^2/M$. |
2405.19122 | Thomas M\"adler | Thomas M\"adler, Olaf Baake, Hamideh Hosseini, Jeffrey Winicour | Apparent horizon tracking in supercritical solutions of the
Einstein-scalar field equations in spherical symmetry in affine-null
coordinates | 14 pages, 13 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Choptuik's critical phenomena in general relativity is revisited in the
affine-null metric formulation of Einstein's equations for a massless scalar
field in spherical symmetry. Numerical solutions are obtained by evolution of
initial data using pseudo-spectral methods. The underlying system consists of
differential equations along the outgoing null rays which can be solved in
sequential form. A new two-parameter family of initial data is presented for
which these equations can be integrated analytically. Specific choices of the
initial data parameters correspond to either an asymptotically flat null cone,
a black hole event horizon or the singular interior of a black hole. Our main
focus is on the interior features of a black hole, for which the affine-null
system is especially well adapted. We present both analytic and numerical
results describing the geometric properties of the apparent horizon and final
singularity. Using a re-gridding technique for the affine parameter, numerical
evolution of initially asymptotically flat supercritical data can be continued
inside the event horizon and track the apparent horizon up to the formation of
the final singularity.
| [
{
"created": "Wed, 29 May 2024 14:28:17 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Jul 2024 03:16:43 GMT",
"version": "v2"
}
] | 2024-07-26 | [
[
"Mädler",
"Thomas",
""
],
[
"Baake",
"Olaf",
""
],
[
"Hosseini",
"Hamideh",
""
],
[
"Winicour",
"Jeffrey",
""
]
] | Choptuik's critical phenomena in general relativity is revisited in the affine-null metric formulation of Einstein's equations for a massless scalar field in spherical symmetry. Numerical solutions are obtained by evolution of initial data using pseudo-spectral methods. The underlying system consists of differential equations along the outgoing null rays which can be solved in sequential form. A new two-parameter family of initial data is presented for which these equations can be integrated analytically. Specific choices of the initial data parameters correspond to either an asymptotically flat null cone, a black hole event horizon or the singular interior of a black hole. Our main focus is on the interior features of a black hole, for which the affine-null system is especially well adapted. We present both analytic and numerical results describing the geometric properties of the apparent horizon and final singularity. Using a re-gridding technique for the affine parameter, numerical evolution of initially asymptotically flat supercritical data can be continued inside the event horizon and track the apparent horizon up to the formation of the final singularity. |
1903.02370 | Andronikos Paliathanasis | Andronikos Paliathanasis, Supriya Pan and Weiqiang Yang | Dynamics of nonlinear interacting dark energy models | 15 pages, 10 figures | International Journal of Modern Physics D Vol. 28, No. 12, 1950161
(2019) | 10.1142/S021827181950161X | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the cosmological dynamics of interacting dark energy models in
which the interaction function is a nonlinear in terms of the energy densities.
Considering explicitly the interaction between a pressureless dark matter and a
scalar field, minimally coupled to Einstein gravity, we explore the dynamics of
the spatially flat FLRW universe for the exponential potential of the scalar
field.. We perform the stability analysis for the three nonlinear interaction
models of our consideration through the analysis of critical points and we
investigate the cosmological parameters and we discuss the physical behaviour
at the critical points. From the analysis of the critical points we find a
number of possibilities that include the stable late time accelerated solution,
$w$CDM-like solution, radiation-like solution and moreover the unstable
inflationary solution as well.
| [
{
"created": "Wed, 6 Mar 2019 13:38:45 GMT",
"version": "v1"
}
] | 2020-01-17 | [
[
"Paliathanasis",
"Andronikos",
""
],
[
"Pan",
"Supriya",
""
],
[
"Yang",
"Weiqiang",
""
]
] | We investigate the cosmological dynamics of interacting dark energy models in which the interaction function is a nonlinear in terms of the energy densities. Considering explicitly the interaction between a pressureless dark matter and a scalar field, minimally coupled to Einstein gravity, we explore the dynamics of the spatially flat FLRW universe for the exponential potential of the scalar field.. We perform the stability analysis for the three nonlinear interaction models of our consideration through the analysis of critical points and we investigate the cosmological parameters and we discuss the physical behaviour at the critical points. From the analysis of the critical points we find a number of possibilities that include the stable late time accelerated solution, $w$CDM-like solution, radiation-like solution and moreover the unstable inflationary solution as well. |
2107.10550 | Soma Heydari | Soma Heydari and Kayoomars Karami | Primordial black holes in nonminimal derivative coupling inflation with
quartic potential and reheating consideration | 32 pages, 6 figures | Eur. Phys. J. C 82, 83 (2022) | 10.1140/epjc/s10052-022-10036-2 | null | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by-nc-sa/4.0/ | We investigate the generation of Primordial Black Holes (PBHs) with the aid
of gravitationally increased friction mechanism originated from the NonMinimal
field Derivative Coupling (NMDC) to gravity framework, with the quartic
potential. Applying the coupling parameter as a two-parted function of inflaton
field and fine-tuning of five parameter assortments we can acquire ultra
slow-roll phase to slow down the inflaton field due to high friction. This
enables us to achieve enough enhancement in the amplitude of curvature
perturbations power spectra to generate PBHs with different masses. The
reheating stage is considered to obtain criteria for PBHs generation during
radiation dominated era. We demonstrate that three cases of asteroid mass PBHs
($10^{-12}M_{\odot}$, $10^{-13}M_{\odot}$, and $10^{-15}M_{\odot})$ can be very
interesting candidates for comprising $100\%$ , $98.3\%$ and $99.1\%$ of the
total Dark Matter (DM) content of the universe. Moreover, we analyse the
production of induced Gravitational Waves (GWs), and illustrate that their
spectra of current density parameter $(\Omega_{\rm GW_0})$ for all parameter
Cases foretold by our model have climaxes which cut the sensitivity curves of
GWs detectors, ergo the veracity of our outcomes can be tested in light of
these detectors. At last, our numerical results exhibit that the spectra of
$\Omega_{\rm GW_0}$ behave as a power-law function with respect to frequency,
$\Omega_{\rm GW_0} (f) \sim (f/f_c)^{n} $, in the vicinity of climaxes. Also,
in the infrared regime $f\ll f_{c}$, the power index satisfies the relation
$n=3-2/\ln(f_c/f)$.
| [
{
"created": "Thu, 22 Jul 2021 10:07:27 GMT",
"version": "v1"
},
{
"created": "Tue, 1 Feb 2022 07:45:13 GMT",
"version": "v2"
}
] | 2022-02-02 | [
[
"Heydari",
"Soma",
""
],
[
"Karami",
"Kayoomars",
""
]
] | We investigate the generation of Primordial Black Holes (PBHs) with the aid of gravitationally increased friction mechanism originated from the NonMinimal field Derivative Coupling (NMDC) to gravity framework, with the quartic potential. Applying the coupling parameter as a two-parted function of inflaton field and fine-tuning of five parameter assortments we can acquire ultra slow-roll phase to slow down the inflaton field due to high friction. This enables us to achieve enough enhancement in the amplitude of curvature perturbations power spectra to generate PBHs with different masses. The reheating stage is considered to obtain criteria for PBHs generation during radiation dominated era. We demonstrate that three cases of asteroid mass PBHs ($10^{-12}M_{\odot}$, $10^{-13}M_{\odot}$, and $10^{-15}M_{\odot})$ can be very interesting candidates for comprising $100\%$ , $98.3\%$ and $99.1\%$ of the total Dark Matter (DM) content of the universe. Moreover, we analyse the production of induced Gravitational Waves (GWs), and illustrate that their spectra of current density parameter $(\Omega_{\rm GW_0})$ for all parameter Cases foretold by our model have climaxes which cut the sensitivity curves of GWs detectors, ergo the veracity of our outcomes can be tested in light of these detectors. At last, our numerical results exhibit that the spectra of $\Omega_{\rm GW_0}$ behave as a power-law function with respect to frequency, $\Omega_{\rm GW_0} (f) \sim (f/f_c)^{n} $, in the vicinity of climaxes. Also, in the infrared regime $f\ll f_{c}$, the power index satisfies the relation $n=3-2/\ln(f_c/f)$. |
2209.12589 | Krinio Marouda | Vitor Cardoso, David Hilditch, Krinio Marouda, Jos\'e Nat\'ario,
Ulrich Sperhake | Curvature and dynamical spacetimes: can we peer into the quantum regime? | 8 pages, 5 figures | null | 10.1088/1361-6382/acb9cd | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Stationary compact astrophysical objects such as black holes and neutron
stars behave as classical systems from the gravitational point of view. Their
(observable) curvature is everywhere "small". Here we investigate whether
mergers of such objects, or other strongly dynamical spacetimes such as
collapsing configurations, may probe the strong-curvature regime of General
Relativity. Our results indicate that dynamical black hole spacetimes always
result in a modest increase $\sim 3$ in the Kretschmann scalar, relative to the
stationary state. Our results show that the Kretschmann scalar can dynamically
increase by orders of magnitude, during the gravitational collapse of scalar
fields, and that the (normalized) peak curvature does not correspond to that of
the critical solution. Nevertheless, without fine tuning of initial data, this
increase lies far below that needed to render quantum-gravity corrections
important.
| [
{
"created": "Mon, 26 Sep 2022 11:18:14 GMT",
"version": "v1"
}
] | 2023-03-08 | [
[
"Cardoso",
"Vitor",
""
],
[
"Hilditch",
"David",
""
],
[
"Marouda",
"Krinio",
""
],
[
"Natário",
"José",
""
],
[
"Sperhake",
"Ulrich",
""
]
] | Stationary compact astrophysical objects such as black holes and neutron stars behave as classical systems from the gravitational point of view. Their (observable) curvature is everywhere "small". Here we investigate whether mergers of such objects, or other strongly dynamical spacetimes such as collapsing configurations, may probe the strong-curvature regime of General Relativity. Our results indicate that dynamical black hole spacetimes always result in a modest increase $\sim 3$ in the Kretschmann scalar, relative to the stationary state. Our results show that the Kretschmann scalar can dynamically increase by orders of magnitude, during the gravitational collapse of scalar fields, and that the (normalized) peak curvature does not correspond to that of the critical solution. Nevertheless, without fine tuning of initial data, this increase lies far below that needed to render quantum-gravity corrections important. |
1004.5162 | Zhao Ren | Zhao Ren Zhao, Huai Fan Li, Li-Chun Zhang, Yue-qin Wu | Hawking radiation and entropy in de Sitter spacetime | 12 pages,Accepted for publication in Astrophysics & Space Science | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using the analytic extension method, we study Hawking radiation of an $(n +
4)$-dimensional Schwarzschild-de Sitter black hole. Under the condition that
the total energy is conserved, taking the reaction of the radiation of
particles to the spacetime into consideration and considering the relation
between the black hole event horizon and cosmological horizon, we obtain the
radiation spectrum of de Sitter spacetime. This radiation spectrum is no longer
a strictly pure thermal spectrum. It is related to the change of the
Bekenstein-Hawking(B-H) entropy corresponding the black hole event horizon and
cosmological horizon. The result satisfies the unitary principle. At the same
time, we also testify that the entropy of de Sitter spacetime is the sum of the
entropy of black hole event horizon and the one of cosmological horizon.
| [
{
"created": "Wed, 28 Apr 2010 23:16:59 GMT",
"version": "v1"
}
] | 2015-03-17 | [
[
"Zhao",
"Zhao Ren",
""
],
[
"Li",
"Huai Fan",
""
],
[
"Zhang",
"Li-Chun",
""
],
[
"Wu",
"Yue-qin",
""
]
] | Using the analytic extension method, we study Hawking radiation of an $(n + 4)$-dimensional Schwarzschild-de Sitter black hole. Under the condition that the total energy is conserved, taking the reaction of the radiation of particles to the spacetime into consideration and considering the relation between the black hole event horizon and cosmological horizon, we obtain the radiation spectrum of de Sitter spacetime. This radiation spectrum is no longer a strictly pure thermal spectrum. It is related to the change of the Bekenstein-Hawking(B-H) entropy corresponding the black hole event horizon and cosmological horizon. The result satisfies the unitary principle. At the same time, we also testify that the entropy of de Sitter spacetime is the sum of the entropy of black hole event horizon and the one of cosmological horizon. |
0707.4625 | Dr. Bikash Chandra Paul | B. C. Paul, P. Thakur and A. Saha | Holographic Dark Energy Model with Modified Generalized Chaplygin Gas | 15 Pages, 1 figure | null | null | null | gr-qc | null | We present a holographic dark energy model of the universe considering
modified generalized Chaplygin gas (GCG). The modified GCG behaves as an
ordinary barotropic fluid in the early epoch when the universe was tiny but
behaves subsequently as a $\Lambda$CDM model at late epoch. An equivalent model
with scalar field is obtained here by constructing the corresponding potential.
The holographic dark energy is identified with the modified GCG and we
determine the corresponding holographic dark energy field and its potential.
The stability of the holographic dark energy in this case is also discussed.
| [
{
"created": "Tue, 31 Jul 2007 14:21:37 GMT",
"version": "v1"
},
{
"created": "Wed, 21 Nov 2007 09:09:47 GMT",
"version": "v2"
}
] | 2007-11-21 | [
[
"Paul",
"B. C.",
""
],
[
"Thakur",
"P.",
""
],
[
"Saha",
"A.",
""
]
] | We present a holographic dark energy model of the universe considering modified generalized Chaplygin gas (GCG). The modified GCG behaves as an ordinary barotropic fluid in the early epoch when the universe was tiny but behaves subsequently as a $\Lambda$CDM model at late epoch. An equivalent model with scalar field is obtained here by constructing the corresponding potential. The holographic dark energy is identified with the modified GCG and we determine the corresponding holographic dark energy field and its potential. The stability of the holographic dark energy in this case is also discussed. |
2001.00556 | Shahram Jalalzadeh | S. Jalalzadeh, M. Rashki and S. Abarghouei Nejad | Classical Universe Arising from Quantum Cosmology | 11 pages, 3 figure, to appear in Physics of the Dark Universe | Phys. Dark Universe, 30, 100741 (2020) | 10.1016/j.dark.2020.100741 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we study the classical limit and unitary evolution of quantum
cosmology by applying the Weyl--Wigner--Groenewold--Moyal formalism of
deformation quantization to quantum cosmology of a homogeneous and isotropic
universe with positive spatial curvature and conformally coupled scalar field.
The corresponding quantum cosmology (similar to the Schr\"{o}dinger
interpretation in canonical quantization scheme of quantum cosmology) is
described by the Moyal--Wheeler--DeWitt equation which has an exact solution in
Moyal phase space, resulting in Wigner quasiprobability distribution function,
peaking over the classical solutions. We show that for a large value of the
quantum number $n$, the emerged classical universe is filled with radiation
with quantum mechanical origin. Also, we introduce a canonical transformation
on the scalar field sector of the model such that the conjugate momenta of the
new canonical variable appear linearly in the transformed total Hamiltonian.
Using this canonical transformation, we show that, it may lead to disentangle
the time from the true dynamical variables. We obtain the time-dependent Wigner
function for a coherent as well as for squeezed states. We show that the peak
of these Wigner functions follows the classical trajectory in the phase space.
| [
{
"created": "Thu, 2 Jan 2020 18:40:20 GMT",
"version": "v1"
},
{
"created": "Fri, 3 Jan 2020 02:53:43 GMT",
"version": "v2"
},
{
"created": "Sat, 31 Oct 2020 12:45:46 GMT",
"version": "v3"
}
] | 2020-11-06 | [
[
"Jalalzadeh",
"S.",
""
],
[
"Rashki",
"M.",
""
],
[
"Nejad",
"S. Abarghouei",
""
]
] | In this paper, we study the classical limit and unitary evolution of quantum cosmology by applying the Weyl--Wigner--Groenewold--Moyal formalism of deformation quantization to quantum cosmology of a homogeneous and isotropic universe with positive spatial curvature and conformally coupled scalar field. The corresponding quantum cosmology (similar to the Schr\"{o}dinger interpretation in canonical quantization scheme of quantum cosmology) is described by the Moyal--Wheeler--DeWitt equation which has an exact solution in Moyal phase space, resulting in Wigner quasiprobability distribution function, peaking over the classical solutions. We show that for a large value of the quantum number $n$, the emerged classical universe is filled with radiation with quantum mechanical origin. Also, we introduce a canonical transformation on the scalar field sector of the model such that the conjugate momenta of the new canonical variable appear linearly in the transformed total Hamiltonian. Using this canonical transformation, we show that, it may lead to disentangle the time from the true dynamical variables. We obtain the time-dependent Wigner function for a coherent as well as for squeezed states. We show that the peak of these Wigner functions follows the classical trajectory in the phase space. |
1810.01283 | Dr. Sudhaker Upadhyay | Sudhaker Upadhyay | Leading-order corrections to charged rotating AdS black holes
thermodynamics | 10 pages, 14 captioned figures, published in General Relativity and
Gravitation | General Relativity and Gravitation (2018) 50:128 | 10.1007/s10714-018-2459-0 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we consider a charged rotating AdS black holes in four
dimensions and study the effects of leading-order thermal corrections on the
thermodynamics of such system explicitly. The first-order corrected
thermodynamical quantities also satisfy the first-law of thermodynamics of the
black holes. The holographic duality between the charged rotating AdS black
holes and Van der Waals fluid is also emphasized through the $P-v$ diagram.
Finally, we study the effects of the leading-order thermal corrections on the
stability of the charged rotating black holes.
| [
{
"created": "Mon, 1 Oct 2018 06:48:40 GMT",
"version": "v1"
}
] | 2018-10-03 | [
[
"Upadhyay",
"Sudhaker",
""
]
] | In this paper, we consider a charged rotating AdS black holes in four dimensions and study the effects of leading-order thermal corrections on the thermodynamics of such system explicitly. The first-order corrected thermodynamical quantities also satisfy the first-law of thermodynamics of the black holes. The holographic duality between the charged rotating AdS black holes and Van der Waals fluid is also emphasized through the $P-v$ diagram. Finally, we study the effects of the leading-order thermal corrections on the stability of the charged rotating black holes. |
2208.13320 | Artyom Astashenok V | Artyom V. Astashenok, Alexander S. Tepliakov | Tsallis holographic dark energy model with event horizon cutoff in
modified gravity | 20 pp., 7 figures; to appear in Int. J. Geom. Meth. Mod. Phys | null | 10.1142/S0219887822502346 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We considered the Tsallis holographic dark energy model in frames of
Nojiri-Odintsov gravity with $f(R)=R+\lambda R^2-\sigma{\mu}/{R}$. For IR
cutoff event horizon is taken. The cosmological evolution of such universe is
investigated for various initial conditions and values of parameters. The
dependence of the Hubble parameter $H$ from time in the future has an
oscillations. It is shown that for $\mu \neq 0$ appearance of singularities are
typical and the time up to these singularities can be relatively small from
cosmological viewpoint. The singularity is associated with the zero of second
deribative of $f(R)$ on $R$. It is interesting to note that these models can
describe observational data from Ia supernovae astrophysics and dependence of
the Hubble parameter from redshift $z$ at least not worse than canonical
$\Lambda$CDM model.
| [
{
"created": "Mon, 29 Aug 2022 00:52:35 GMT",
"version": "v1"
}
] | 2023-01-11 | [
[
"Astashenok",
"Artyom V.",
""
],
[
"Tepliakov",
"Alexander S.",
""
]
] | We considered the Tsallis holographic dark energy model in frames of Nojiri-Odintsov gravity with $f(R)=R+\lambda R^2-\sigma{\mu}/{R}$. For IR cutoff event horizon is taken. The cosmological evolution of such universe is investigated for various initial conditions and values of parameters. The dependence of the Hubble parameter $H$ from time in the future has an oscillations. It is shown that for $\mu \neq 0$ appearance of singularities are typical and the time up to these singularities can be relatively small from cosmological viewpoint. The singularity is associated with the zero of second deribative of $f(R)$ on $R$. It is interesting to note that these models can describe observational data from Ia supernovae astrophysics and dependence of the Hubble parameter from redshift $z$ at least not worse than canonical $\Lambda$CDM model. |
gr-qc/0311077 | Adam Szereszewski | Adam Szereszewski, Jacek Tafel | Perfect Fluid Spacetimes With Two Symmetries | 7 pages, no figures, LaTeX2e, to be published in Class. Quant. Grav | Class.Quant.Grav. 21 (2004) 1755-1760 | 10.1088/0264-9381/21/7/003 | null | gr-qc | null | A method of solving perfect fluid Einstein equations with two commuting
spacelike Killing vectors is presented. Given a spacelike 2-dimensional surface
in the 3-dimensional nonphysical Minkowski space the field equations reduce to
a single nonlinear differential equation. An example is discussed.
| [
{
"created": "Mon, 24 Nov 2003 12:19:29 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Szereszewski",
"Adam",
""
],
[
"Tafel",
"Jacek",
""
]
] | A method of solving perfect fluid Einstein equations with two commuting spacelike Killing vectors is presented. Given a spacelike 2-dimensional surface in the 3-dimensional nonphysical Minkowski space the field equations reduce to a single nonlinear differential equation. An example is discussed. |
gr-qc/0007038 | Cristian Martinez | Norman Cruz and Cristian Martinez | Cosmological scaling solutions of minimally coupled scalar fields in
three dimensions | LaTeX2e, 11 pages, 4 figures. To be published in Classical and
Quantum Gravity | Class.Quant.Grav. 17 (2000) 2867-2874 | 10.1088/0264-9381/17/15/302 | CECS-PHY-00/02 | gr-qc | null | We examine Friedmann-Robertson-Walker models in three spacetime dimensions.
The matter content of the models is composed of a perfect fluid, with a
$\gamma$-law equation of state, and a homogeneous scalar field minimally
coupled to gravity with a self-interacting potential whose energy density
red-shifts as $a^{-2 \nu}$, where a denotes the scale factor. Cosmological
solutions are presented for different range of values of $\gamma$ and $\nu$.
The potential required to agree with the above red-shift for the scalar field
energy density is also calculated.
| [
{
"created": "Mon, 17 Jul 2000 23:10:10 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Cruz",
"Norman",
""
],
[
"Martinez",
"Cristian",
""
]
] | We examine Friedmann-Robertson-Walker models in three spacetime dimensions. The matter content of the models is composed of a perfect fluid, with a $\gamma$-law equation of state, and a homogeneous scalar field minimally coupled to gravity with a self-interacting potential whose energy density red-shifts as $a^{-2 \nu}$, where a denotes the scale factor. Cosmological solutions are presented for different range of values of $\gamma$ and $\nu$. The potential required to agree with the above red-shift for the scalar field energy density is also calculated. |
gr-qc/0006028 | Daniel Sforza | Mario A. Castagnino, Fabian H. Gaioli, and Daniel M. Sforza | Entropy generation in cosmological particle creation | 14 pages (Latex manuscript) | Gen.Rel.Grav. 28 (1996) 1129 | 10.1007/BF02113163 | null | gr-qc | null | A very simplified model of the Universe is considered in order to propose an
alternative approach to the irreversible evolution of the Universe at very
early times. The entropy generation at the quantum stage can be thought as a
consequence of an instability of the system. Then particle creation arises from
this instability.
| [
{
"created": "Wed, 7 Jun 2000 20:41:33 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Castagnino",
"Mario A.",
""
],
[
"Gaioli",
"Fabian H.",
""
],
[
"Sforza",
"Daniel M.",
""
]
] | A very simplified model of the Universe is considered in order to propose an alternative approach to the irreversible evolution of the Universe at very early times. The entropy generation at the quantum stage can be thought as a consequence of an instability of the system. Then particle creation arises from this instability. |
gr-qc/9910006 | Zbigniew Haba | Z. Haba | Decoherence and quantum mechanics in a gravitational field | 11 pages, LaTex file | null | null | IFT UWr 925/1999 | gr-qc | null | Quantum mechanical interference of wave functions leads to some difficulties
if a probability density is considered as a source of gravity. We show that an
introduction of a quantum energy-momentum tensor as a source term in Einstein
equations can be consistent with general relativity if the gravitational waves
are quantized.
| [
{
"created": "Mon, 4 Oct 1999 08:35:56 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Haba",
"Z.",
""
]
] | Quantum mechanical interference of wave functions leads to some difficulties if a probability density is considered as a source of gravity. We show that an introduction of a quantum energy-momentum tensor as a source term in Einstein equations can be consistent with general relativity if the gravitational waves are quantized. |
0706.1979 | Jacobo Diaz Polo | Jacobo Diaz-Polo and Enrique Fernandez-Borja | Black hole radiation spectrum in LQG: Isolated Horizon framework | 6 pages, 2 figures; version to appear in Classical and Quantum
Gravity | Class.Quant.Grav.25:105007,2008 | 10.1088/0264-9381/25/10/105007 | null | gr-qc | null | Recent detailed analysis within the Loop Quantum Gravity calculation of black
hole entropy shows a stair-like structure in the behavior of entropy as a
function of horizon area. The non-trivial distribution of the degeneracy of the
black hole horizon area eigenstates is at the origin of this behavior. This
degeneracy distribution is analyzed and a phenomenological model is put forward
to study the implications of this distribution in the black hole radiation
spectrum. Some qualitative quantum effects are obtained within the isolated
horizon framework. This result provides us with a possible observational test
of this model for quantum black holes.
| [
{
"created": "Thu, 14 Jun 2007 18:30:06 GMT",
"version": "v1"
},
{
"created": "Fri, 18 Apr 2008 11:41:02 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Diaz-Polo",
"Jacobo",
""
],
[
"Fernandez-Borja",
"Enrique",
""
]
] | Recent detailed analysis within the Loop Quantum Gravity calculation of black hole entropy shows a stair-like structure in the behavior of entropy as a function of horizon area. The non-trivial distribution of the degeneracy of the black hole horizon area eigenstates is at the origin of this behavior. This degeneracy distribution is analyzed and a phenomenological model is put forward to study the implications of this distribution in the black hole radiation spectrum. Some qualitative quantum effects are obtained within the isolated horizon framework. This result provides us with a possible observational test of this model for quantum black holes. |
1906.06372 | Eugen Radu | Burkhard Kleihaus, Jutta Kunz and Eugen Radu | Balancing a static black ring with a phantom scalar field | 12 pages, 5 figures | null | 10.1016/j.physletb.2019.134892 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | All known five dimensional, asymptotically flat, static black rings possess
conical singularities. However, there is no fundamental obstruction forbidding
the existence of balanced configurations, and we show that the
Einstein--Klein-Gordon equations admit (numerical) solutions describing static
asymptotically flat black rings, which are regular on and outside the event
horizon. The scalar field is 'phantom', which creates the self-repulsion
necessary to balance the black rings. Similar solutions are likely to exist in
other spacetime dimensions, the basic properties of a line element describing a
four dimensional, asymptotically flat black ring geometry being discussed.
| [
{
"created": "Fri, 14 Jun 2019 19:13:05 GMT",
"version": "v1"
}
] | 2019-09-04 | [
[
"Kleihaus",
"Burkhard",
""
],
[
"Kunz",
"Jutta",
""
],
[
"Radu",
"Eugen",
""
]
] | All known five dimensional, asymptotically flat, static black rings possess conical singularities. However, there is no fundamental obstruction forbidding the existence of balanced configurations, and we show that the Einstein--Klein-Gordon equations admit (numerical) solutions describing static asymptotically flat black rings, which are regular on and outside the event horizon. The scalar field is 'phantom', which creates the self-repulsion necessary to balance the black rings. Similar solutions are likely to exist in other spacetime dimensions, the basic properties of a line element describing a four dimensional, asymptotically flat black ring geometry being discussed. |
0710.0416 | Dah-Wei Chiou | Dah-Wei Chiou | Effective Dynamics, Big Bounces and Scaling Symmetry in Bianchi Type I
Loop Quantum Cosmology | 19 pages, 6 figures, 1 table; one reference added; version to appear
in PRD | Phys.Rev.D76:124037,2007 | 10.1103/PhysRevD.76.124037 | IGC-07/9-4 | gr-qc | null | The detailed formulation for loop quantum cosmology (LQC) in the Bianchi I
model with a scalar massless field has been constructed. In this paper, its
effective dynamics is studied in two improved strategies for implementing the
LQC discreteness corrections. Both schemes show that the big bang is replaced
by the big bounces, which take place up to three times, once in each diagonal
direction, when the area or volume scale factor approaches the critical values
in the Planck regime measured by the reference of the scalar field momentum.
These two strategies give different evolutions: In one scheme, the effective
dynamics is independent of the choice of the finite sized cell prescribed to
make Hamiltonian finite; in the other, the effective dynamics reacts to the
macroscopic scales introduced by the boundary conditions. Both schemes reveal
interesting symmetries of scaling, which are reminiscent of the relational
interpretation of quantum mechanics and also suggest that the fundamental
spatial scale (area gap) may give rise to a temporal scale.
| [
{
"created": "Tue, 2 Oct 2007 00:32:18 GMT",
"version": "v1"
},
{
"created": "Mon, 17 Dec 2007 23:20:54 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Chiou",
"Dah-Wei",
""
]
] | The detailed formulation for loop quantum cosmology (LQC) in the Bianchi I model with a scalar massless field has been constructed. In this paper, its effective dynamics is studied in two improved strategies for implementing the LQC discreteness corrections. Both schemes show that the big bang is replaced by the big bounces, which take place up to three times, once in each diagonal direction, when the area or volume scale factor approaches the critical values in the Planck regime measured by the reference of the scalar field momentum. These two strategies give different evolutions: In one scheme, the effective dynamics is independent of the choice of the finite sized cell prescribed to make Hamiltonian finite; in the other, the effective dynamics reacts to the macroscopic scales introduced by the boundary conditions. Both schemes reveal interesting symmetries of scaling, which are reminiscent of the relational interpretation of quantum mechanics and also suggest that the fundamental spatial scale (area gap) may give rise to a temporal scale. |
1301.7688 | Tim Koslowski A | Henrique Gomes, Tim Koslowski | Shape Dynamics and Gauge-Gravity Duality | 4 pages, LaTeX, contribution to the 13th Marcel Grossmann Meeting | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The dynamics of gravity can be described by two different systems. The first
is the familiar spacetime picture of General Relativity, the other is the
conformal picture of Shape Dynamics. We argue that the bulk equivalence of
General Relativity and Shape Dynamics is a natural setting to discuss familiar
bulk/boundary dualities. We discuss consequences of the Shape Dynamics
description of gravity as well as the issue why the bulk equivalence is not
explicitly seen in the General Relativity description of gravity.
| [
{
"created": "Thu, 31 Jan 2013 17:09:47 GMT",
"version": "v1"
}
] | 2013-02-01 | [
[
"Gomes",
"Henrique",
""
],
[
"Koslowski",
"Tim",
""
]
] | The dynamics of gravity can be described by two different systems. The first is the familiar spacetime picture of General Relativity, the other is the conformal picture of Shape Dynamics. We argue that the bulk equivalence of General Relativity and Shape Dynamics is a natural setting to discuss familiar bulk/boundary dualities. We discuss consequences of the Shape Dynamics description of gravity as well as the issue why the bulk equivalence is not explicitly seen in the General Relativity description of gravity. |
1805.12246 | James B. Hartle | James B. Hartle (UCSB) | The Quantum Mechanics of Cosmology | 92 pages, 14 figures, presented at 7th Jerusalem Winter School 1990
on Quantum Cosmology and Baby Universes, posted here because the school
proceedings are out of print | null | null | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Notes from the lectures by the author at the 7th Jerusalem Winter School 1990
on Quantum Cosmology and Baby Universes. The lectures covered quantum mechanics
for closed systems like the universe, generalized quantum mechanics, time in
quantum mechanics, the quantum mechanics spacetime, and practical quantum
cosmology. References have not been updated.
| [
{
"created": "Wed, 30 May 2018 22:18:06 GMT",
"version": "v1"
}
] | 2018-06-01 | [
[
"Hartle",
"James B.",
"",
"UCSB"
]
] | Notes from the lectures by the author at the 7th Jerusalem Winter School 1990 on Quantum Cosmology and Baby Universes. The lectures covered quantum mechanics for closed systems like the universe, generalized quantum mechanics, time in quantum mechanics, the quantum mechanics spacetime, and practical quantum cosmology. References have not been updated. |
1503.04734 | Mariano Cadoni | Mariano Cadoni and Edgardo Franzin | Asymptotically flat black holes sourced by a massless scalar field | 12 pages, no figures. Refs. [27-33] added. Some remarks about
previous derivation and stability of solution (5.4) added | Phys. Rev. D 91, 104011 (2015) | 10.1103/PhysRevD.91.104011 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive exact, asymptotically flat black hole solutions of Einstein-scalar
gravity sourced by a non trivial scalar field with $1/r$ asymptotic behaviour.
They are determined using an ansatz for the scalar field profile and working
out, together with the metric functions, the corresponding form of the scalar
self-interaction potential. Near to the singularity the black hole behaves as
the Janis-Newmann-Winicour-Wyman solution. We also work out a consistent
thermodynamical description of our black hole solutions. For large mass our
hairy black holes have the same thermodynamical behaviour of the Schwarzschild
black hole, whereas for small masses they differ substantially from the latter.
| [
{
"created": "Mon, 16 Mar 2015 17:15:07 GMT",
"version": "v1"
},
{
"created": "Mon, 23 Mar 2015 12:55:36 GMT",
"version": "v2"
}
] | 2015-05-20 | [
[
"Cadoni",
"Mariano",
""
],
[
"Franzin",
"Edgardo",
""
]
] | We derive exact, asymptotically flat black hole solutions of Einstein-scalar gravity sourced by a non trivial scalar field with $1/r$ asymptotic behaviour. They are determined using an ansatz for the scalar field profile and working out, together with the metric functions, the corresponding form of the scalar self-interaction potential. Near to the singularity the black hole behaves as the Janis-Newmann-Winicour-Wyman solution. We also work out a consistent thermodynamical description of our black hole solutions. For large mass our hairy black holes have the same thermodynamical behaviour of the Schwarzschild black hole, whereas for small masses they differ substantially from the latter. |
2301.01938 | Haximjan Abdusattar | Haximjan Abdusattar, Shi-Bei Kong, Hongsheng Zhang, Ya-Peng Hu | Phase Transitions and Critical Phenomena for the FRW Universe in an
Effective Scalar-Tensor Theory | 12 pages, 1 figures | null | null | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We find phase transitions and critical phenomena of the FRW
(Friedmann-Robertson-Walker) universe in the framework of an effective
scalar-tensor theory that belongs to the Horndeski class. We identify the
thermodynamic pressure (generalized force) $P$ of the FRW universe in this
theory with the work density $W$ of the perfect fluid, which is a natural
definition directly read out from the first law of thermodynamics. We derive
the thermodynamic equation of state $P=P(V, T)$ for the FRW universe in this
theory and make a thorough discussion of its $P$-$V$ phase transitions and
critical phenomena. We calculate the critical exponents, and show that they are
the same with the mean field theory, and thus obey the scaling laws.
| [
{
"created": "Thu, 5 Jan 2023 07:20:46 GMT",
"version": "v1"
}
] | 2023-01-06 | [
[
"Abdusattar",
"Haximjan",
""
],
[
"Kong",
"Shi-Bei",
""
],
[
"Zhang",
"Hongsheng",
""
],
[
"Hu",
"Ya-Peng",
""
]
] | We find phase transitions and critical phenomena of the FRW (Friedmann-Robertson-Walker) universe in the framework of an effective scalar-tensor theory that belongs to the Horndeski class. We identify the thermodynamic pressure (generalized force) $P$ of the FRW universe in this theory with the work density $W$ of the perfect fluid, which is a natural definition directly read out from the first law of thermodynamics. We derive the thermodynamic equation of state $P=P(V, T)$ for the FRW universe in this theory and make a thorough discussion of its $P$-$V$ phase transitions and critical phenomena. We calculate the critical exponents, and show that they are the same with the mean field theory, and thus obey the scaling laws. |
gr-qc/9603063 | Carlo Rovelli | Carlo Rovelli | Black Hole Entropy from Loop Quantum Gravity | 5 pages, latex-revtex, no figures | Phys.Rev.Lett.77:3288-3291,1996 | 10.1103/PhysRevLett.77.3288 | null | gr-qc | null | We argue that the statistical entropy relevant for the thermal interactions
of a black hole with its surroundings is (the logarithm of) the number of
quantum microstates of the hole which are distinguishable from the hole's
exterior, and which correspond to a given hole's macroscopic configuration. We
compute this number explicitly from first principles, for a Schwarzschild black
hole, using nonperturbative quantum gravity in the loop representation. We
obtain a black hole entropy proportional to the area, as in the
Bekenstein-Hawking formula.
| [
{
"created": "Sat, 30 Mar 1996 19:45:20 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Rovelli",
"Carlo",
""
]
] | We argue that the statistical entropy relevant for the thermal interactions of a black hole with its surroundings is (the logarithm of) the number of quantum microstates of the hole which are distinguishable from the hole's exterior, and which correspond to a given hole's macroscopic configuration. We compute this number explicitly from first principles, for a Schwarzschild black hole, using nonperturbative quantum gravity in the loop representation. We obtain a black hole entropy proportional to the area, as in the Bekenstein-Hawking formula. |
gr-qc/0207098 | Keisuke Taniguchi | Keisuke Taniguchi and Eric Gourgoulhon | Quasiequilibrium sequences of synchronized and irrotational binary
neutron stars in general relativity. III. Identical and different mass stars
with gamma=2 | 17 pages, revtex file with 14 figures and 4 tables, accepted for
publication in Phys. Rev. D | Phys.Rev. D66 (2002) 104019 | 10.1103/PhysRevD.66.104019 | null | gr-qc astro-ph | null | We present the first computations of quasiequilibrium binary neutron stars
with different mass components in general relativity, within the
Isenberg-Wilson-Mathews approximation. We consider both cases of synchronized
rotation and irrotational motion. A polytropic equation of state is used with
the adiabatic index gamma=2. The computations have been performed for the
following combinations of stars: (M/R)_{star 1} vs. (M/R)_{star 2} = 0.12 vs.
(0.12, 0.13, 0.14), 0.14 vs. (0.14, 0.15, 0.16), 0.16 vs. (0.16, 0.17, 0.18),
and 0.18 vs. 0.18, where (M/R) denotes the compactness parameter of infinitely
separated stars of the same baryon number. It is found that for identical mass
binary systems there is no turning point of the binding energy (ADM mass)
before the end point of the sequence (mass shedding point) in the irrotational
case, while there is one before the end point of the sequence (contact point)
in the synchronized case. On the other hand, in the different mass case, the
sequence ends by the tidal disruption of the less massive star (mass shedding
point). It is then more difficult to find a turning point in the ADM mass.
Furthermore, we find that the deformation of each star depends mainly on the
orbital separation and the mass ratio and very weakly on its compactness. On
the other side, the decrease of the central energy density depends on the
compactness of the star and not on that of the companion.
| [
{
"created": "Thu, 25 Jul 2002 03:27:11 GMT",
"version": "v1"
},
{
"created": "Tue, 1 Oct 2002 05:57:07 GMT",
"version": "v2"
}
] | 2009-11-07 | [
[
"Taniguchi",
"Keisuke",
""
],
[
"Gourgoulhon",
"Eric",
""
]
] | We present the first computations of quasiequilibrium binary neutron stars with different mass components in general relativity, within the Isenberg-Wilson-Mathews approximation. We consider both cases of synchronized rotation and irrotational motion. A polytropic equation of state is used with the adiabatic index gamma=2. The computations have been performed for the following combinations of stars: (M/R)_{star 1} vs. (M/R)_{star 2} = 0.12 vs. (0.12, 0.13, 0.14), 0.14 vs. (0.14, 0.15, 0.16), 0.16 vs. (0.16, 0.17, 0.18), and 0.18 vs. 0.18, where (M/R) denotes the compactness parameter of infinitely separated stars of the same baryon number. It is found that for identical mass binary systems there is no turning point of the binding energy (ADM mass) before the end point of the sequence (mass shedding point) in the irrotational case, while there is one before the end point of the sequence (contact point) in the synchronized case. On the other hand, in the different mass case, the sequence ends by the tidal disruption of the less massive star (mass shedding point). It is then more difficult to find a turning point in the ADM mass. Furthermore, we find that the deformation of each star depends mainly on the orbital separation and the mass ratio and very weakly on its compactness. On the other side, the decrease of the central energy density depends on the compactness of the star and not on that of the companion. |
1401.1838 | Miguel Sabido | J. C. L\'opez-Dom\'inguez, J. E. Rosales-Quintero and M. Sabido | Comments On Torsion and MacDowell-Mansouri gravity | 14 pages, no figures, matches published version | Int.J.Mod.Phys.D 27 (2017) 03, 1850018 | 10.1142/S0218271818500189 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Starting with the MacDowell-Mansouri formulation of gravity with a $SO(4,1)$
gauge group, we introduce new parameters into the action to include the
non-dynamical Holst term, and the topological Nieh-Yan and Pontryagin classes.
Then, we consider the new parameters as fields and analyze the solutions coming
from their equations of motion. The new fields introduce torsional
contributions to the theory that modify Einstein's equations.
| [
{
"created": "Wed, 8 Jan 2014 21:33:30 GMT",
"version": "v1"
},
{
"created": "Sat, 15 May 2021 03:19:22 GMT",
"version": "v2"
}
] | 2021-05-18 | [
[
"López-Domínguez",
"J. C.",
""
],
[
"Rosales-Quintero",
"J. E.",
""
],
[
"Sabido",
"M.",
""
]
] | Starting with the MacDowell-Mansouri formulation of gravity with a $SO(4,1)$ gauge group, we introduce new parameters into the action to include the non-dynamical Holst term, and the topological Nieh-Yan and Pontryagin classes. Then, we consider the new parameters as fields and analyze the solutions coming from their equations of motion. The new fields introduce torsional contributions to the theory that modify Einstein's equations. |
gr-qc/9212014 | Malcolm MacCallum | M.A.H. MacCallum | Anisotropic and inhomogeneous cosmologies | 21 pp | The Renaissance of General Relativity and Cosmology (A survey to
celebrate the 65th birthday of Dennis Sciama), ed. G. Ellis, A. Lanza and
J.C. Miller, Cambridge University Press (1993), pp. 213-233 | null | null | gr-qc | null | This review was given at the 65th birthday meeting of D.W. Sciama, The
Renaissance of General Relativity and Cosmology, to be published by Cambridge
University Press. It presents progress in the understanding of non-standard
relativistic cosmologies during Sciama's career, organized by the areas of
application rather than the mathematical types of the models.
| [
{
"created": "Mon, 21 Dec 1992 15:59:48 GMT",
"version": "v1"
}
] | 2008-02-12 | [
[
"MacCallum",
"M. A. H.",
""
]
] | This review was given at the 65th birthday meeting of D.W. Sciama, The Renaissance of General Relativity and Cosmology, to be published by Cambridge University Press. It presents progress in the understanding of non-standard relativistic cosmologies during Sciama's career, organized by the areas of application rather than the mathematical types of the models. |
2004.11843 | Jaume Haro | Jaume Haro and Llibert Arest\'e Sal\'o | The spectrum of Gravitational Waves, their overproduction in
quintessential inflation and its influence in the reheating temperature | 51 pages, 4 figures, 1 table, new material and references added.
Version accepted for publication in Universe | null | 10.3390/universe6060087 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | One of the most important issues in an inflationary theory as standard or
quintessential inflation is the mechanism to reheat the universe after the end
of the inflationary period in order to match with the Hot Big Bang universe. In
quintessential inflation two mechanisms are frequently used, namely the
reheating via gravitational particle production which is, as we will see, very
efficient when the phase transition from the end of inflation to a kinetic
regime (all the energy of the inflaton field is kinetic) is very abrupt, and
the so-called instant preheating which is used for a very smooth phase
transition because in that case the gravitational particle production is very
inefficient.
In the present work, a detailed study of these mechanisms is done, obtaining
bounds for the reheating temperature and the range of the parameters involved
in each reheating mechanism in order that the Gravitational Waves (GWs)
produced at the beginning of kination do not disturb the Big Bang
Nucleosynthesis (BBN) success.
| [
{
"created": "Fri, 24 Apr 2020 16:29:45 GMT",
"version": "v1"
},
{
"created": "Mon, 4 May 2020 10:49:36 GMT",
"version": "v2"
},
{
"created": "Mon, 22 Jun 2020 09:16:39 GMT",
"version": "v3"
}
] | 2023-01-03 | [
[
"Haro",
"Jaume",
""
],
[
"Saló",
"Llibert Aresté",
""
]
] | One of the most important issues in an inflationary theory as standard or quintessential inflation is the mechanism to reheat the universe after the end of the inflationary period in order to match with the Hot Big Bang universe. In quintessential inflation two mechanisms are frequently used, namely the reheating via gravitational particle production which is, as we will see, very efficient when the phase transition from the end of inflation to a kinetic regime (all the energy of the inflaton field is kinetic) is very abrupt, and the so-called instant preheating which is used for a very smooth phase transition because in that case the gravitational particle production is very inefficient. In the present work, a detailed study of these mechanisms is done, obtaining bounds for the reheating temperature and the range of the parameters involved in each reheating mechanism in order that the Gravitational Waves (GWs) produced at the beginning of kination do not disturb the Big Bang Nucleosynthesis (BBN) success. |
1107.4294 | Johannes Hartung | Johannes Hartung and Jan Steinhoff | Next-to-next-to-leading order post-Newtonian spin(1)-spin(2) Hamiltonian
for self-gravitating binaries | 7 pages, v2: published version | Ann. Phys. (Berlin) 523:919 (2011) | 10.1002/andp.201100163 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present the next-to-next-to-leading order post-Newtonian (PN)
spin(1)-spin(2) Hamiltonian for two self-gravitating spinning compact objects.
If both objects are rapidly rotating, then the corresponding interaction is
comparable in strength to a 4PN effect. The Hamiltonian is checked via the
global Poincare algebra with the center-of-mass vector uniquely determined by
an ansatz.
| [
{
"created": "Thu, 21 Jul 2011 15:08:05 GMT",
"version": "v1"
},
{
"created": "Tue, 4 Oct 2011 10:25:09 GMT",
"version": "v2"
}
] | 2011-10-05 | [
[
"Hartung",
"Johannes",
""
],
[
"Steinhoff",
"Jan",
""
]
] | We present the next-to-next-to-leading order post-Newtonian (PN) spin(1)-spin(2) Hamiltonian for two self-gravitating spinning compact objects. If both objects are rapidly rotating, then the corresponding interaction is comparable in strength to a 4PN effect. The Hamiltonian is checked via the global Poincare algebra with the center-of-mass vector uniquely determined by an ansatz. |
1302.1880 | Christopher Burton | C. D. Burton | Finite temperature R-squared quantum gravity | 14 pages | null | null | MIFPA-13-05 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The quantum gravity path integral's measure can be written as the product of
classical backgrounds and quantum fluctuations about each background. After
proving that fluctuations about the background do not diffuse in Hilbert space
and obey the laws of many-body statistics, their probability distributions,
entropy, and expected background are determined. This background obeys
expectation-valued Einstein equations and features an entropy-based positive
cosmological constant. From the fluctuation probability distributions, a finite
temperature, R-squared, quantum gravity path integral is constructed whose
action presents an interaction picture of quantum gravity that `moves with' the
expected background in Hilbert space. Within this interaction picture of
quantum fluctuations about an expected background, the fields required to
describe quantum gravity have been transformed into `ordinary' quantum fields
propagating on this `rigid' or `fixed' expected background. Back-reaction has
been fully accounted for, and the quantum formulation is manifestly background
independent.
| [
{
"created": "Thu, 7 Feb 2013 21:10:24 GMT",
"version": "v1"
}
] | 2013-02-11 | [
[
"Burton",
"C. D.",
""
]
] | The quantum gravity path integral's measure can be written as the product of classical backgrounds and quantum fluctuations about each background. After proving that fluctuations about the background do not diffuse in Hilbert space and obey the laws of many-body statistics, their probability distributions, entropy, and expected background are determined. This background obeys expectation-valued Einstein equations and features an entropy-based positive cosmological constant. From the fluctuation probability distributions, a finite temperature, R-squared, quantum gravity path integral is constructed whose action presents an interaction picture of quantum gravity that `moves with' the expected background in Hilbert space. Within this interaction picture of quantum fluctuations about an expected background, the fields required to describe quantum gravity have been transformed into `ordinary' quantum fields propagating on this `rigid' or `fixed' expected background. Back-reaction has been fully accounted for, and the quantum formulation is manifestly background independent. |
2207.00955 | Damien A. Easson | J. E. Lesnefsky, D. A. Easson and P. C. W. Davies | On the past-completeness of inflationary spacetimes | 14 pages, 4 figures, significant revisions, matches version to appear
in PRD | null | 10.1103/PhysRevD.107.044024 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We discuss the question of whether or not inflationary spacetimes can be
geodesically complete in the infinite past. Geodesic completeness is a
necessary condition for averting an initial singularity during eternal
inflation. It is frequently argued that cosmological models which are expanding
sufficiently fast (having average Hubble expansion rate $H_{avg}>0$) must be
incomplete in null and timelike past directions. This well-known conjecture
relies on specific bounds on the integral of the Hubble parameter over a
past-directed timelike or null geodesic. As stated, we show this claim is an
open issue. We show that the calculation of $H_{avg}$ yields a continuum of
results for a given spacetime predicated upon the underlying topological
assumptions. We present an improved definition for $H_{avg}$ and introduce an
uncountably infinite cohort of cosmological solutions which are geodesically
complete despite having $H_{avg}>0$. We discuss a standardized definition for
inflationary spacetimes as well as quantum (semi-classical) cosmological
concerns over physically reasonable scale factors.
| [
{
"created": "Sun, 3 Jul 2022 04:58:37 GMT",
"version": "v1"
},
{
"created": "Wed, 25 Jan 2023 00:35:49 GMT",
"version": "v2"
}
] | 2023-02-22 | [
[
"Lesnefsky",
"J. E.",
""
],
[
"Easson",
"D. A.",
""
],
[
"Davies",
"P. C. W.",
""
]
] | We discuss the question of whether or not inflationary spacetimes can be geodesically complete in the infinite past. Geodesic completeness is a necessary condition for averting an initial singularity during eternal inflation. It is frequently argued that cosmological models which are expanding sufficiently fast (having average Hubble expansion rate $H_{avg}>0$) must be incomplete in null and timelike past directions. This well-known conjecture relies on specific bounds on the integral of the Hubble parameter over a past-directed timelike or null geodesic. As stated, we show this claim is an open issue. We show that the calculation of $H_{avg}$ yields a continuum of results for a given spacetime predicated upon the underlying topological assumptions. We present an improved definition for $H_{avg}$ and introduce an uncountably infinite cohort of cosmological solutions which are geodesically complete despite having $H_{avg}>0$. We discuss a standardized definition for inflationary spacetimes as well as quantum (semi-classical) cosmological concerns over physically reasonable scale factors. |
gr-qc/0601042 | Alfredo Sandoval-Villalbazo | A. Sandoval-Villalbazo, A. L. Garcia-Perciante and L. S. Garcia-Colin | Hyperbolic heat equation in Kaluza's magnetohydrodynamics | 14 pages, no figures | Gen.Rel.Grav.39:1287-1296,2007 | 10.1007/s10714-007-0460-0 | null | gr-qc astro-ph | null | This paper shows that a hyperbolic equation for heat conduction can be
obtained directly using the tenets of linear irreversible thermodynamics in the
context of the five dimensional space-time metric originally proposed by T.
Kaluza back in 1922. The associated speed of propagation is slightly lower than
the speed of light by a factor inversely proportional to the specific charge of
the fluid element. Moreover, consistency with the second law of thermodynamics
is achieved. Possible implications in the context of physics of clusters of
galaxies of this result are briefly discussed.
| [
{
"created": "Wed, 11 Jan 2006 19:06:15 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Sandoval-Villalbazo",
"A.",
""
],
[
"Garcia-Perciante",
"A. L.",
""
],
[
"Garcia-Colin",
"L. S.",
""
]
] | This paper shows that a hyperbolic equation for heat conduction can be obtained directly using the tenets of linear irreversible thermodynamics in the context of the five dimensional space-time metric originally proposed by T. Kaluza back in 1922. The associated speed of propagation is slightly lower than the speed of light by a factor inversely proportional to the specific charge of the fluid element. Moreover, consistency with the second law of thermodynamics is achieved. Possible implications in the context of physics of clusters of galaxies of this result are briefly discussed. |
1208.4871 | Eanna E. Flanagan | Sergei Dyda, Eanna E. Flanagan and Marc Kamionkowski | Vacuum Instability in Chern-Simons Gravity | 8 pages, 2 figures; final published version | null | 10.1103/PhysRevD.86.124031 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We explore perturbations about a Friedmann-Robertson-Walker background in
Chern-Simons gravity. At large momenta one of the two circularly polarized
tensor modes becomes ghostlike. We argue that nevertheless the theory does not
exhibit classical runaway solutions, except possibly in the relativistic
nonlinear regime. However, the ghost modes cause the vacuum state to be quantum
mechanically unstable, with a decay rate that is naively infinite. The decay
rate can be made finite only if one interprets the theory as an effective
quantum field theory valid up to some momentum cutoff, which violates Lorentz
invariance. By demanding that the energy density in photons created by vacuum
decay over the lifetime of the Universe not violate observational bounds, we
derive strong constraints on the two dimensional parameter space of the theory,
consisting of the cutoff and the Chern-Simons mass.
| [
{
"created": "Thu, 23 Aug 2012 21:59:07 GMT",
"version": "v1"
},
{
"created": "Wed, 28 Nov 2012 13:58:37 GMT",
"version": "v2"
}
] | 2013-05-30 | [
[
"Dyda",
"Sergei",
""
],
[
"Flanagan",
"Eanna E.",
""
],
[
"Kamionkowski",
"Marc",
""
]
] | We explore perturbations about a Friedmann-Robertson-Walker background in Chern-Simons gravity. At large momenta one of the two circularly polarized tensor modes becomes ghostlike. We argue that nevertheless the theory does not exhibit classical runaway solutions, except possibly in the relativistic nonlinear regime. However, the ghost modes cause the vacuum state to be quantum mechanically unstable, with a decay rate that is naively infinite. The decay rate can be made finite only if one interprets the theory as an effective quantum field theory valid up to some momentum cutoff, which violates Lorentz invariance. By demanding that the energy density in photons created by vacuum decay over the lifetime of the Universe not violate observational bounds, we derive strong constraints on the two dimensional parameter space of the theory, consisting of the cutoff and the Chern-Simons mass. |
gr-qc/9502025 | Carlos Kozameh | Simonetta Frittelli, Carlos Kozameh, Ted Newman | Lorentzian Metrics from Characteristic Surfaces | 14 pages, tarred, compressed and uuencode RTF file | J.Math.Phys. 36 (1995) 4975-4983 | 10.1063/1.531209 | null | gr-qc | null | The following issue is raised and discussed; when do families of foliations
by hypersurfaces on a given four dimensional manifold become the null surfaces
of some unknown, but to be determined, metric $g_{ab}(x)$? It follows from
these results that one can use these surfaces as fundamental variables for GR.
| [
{
"created": "Fri, 10 Feb 1995 07:57:37 GMT",
"version": "v1"
},
{
"created": "Sat, 11 Feb 1995 11:19:06 GMT",
"version": "v2"
}
] | 2009-10-28 | [
[
"Frittelli",
"Simonetta",
""
],
[
"Kozameh",
"Carlos",
""
],
[
"Newman",
"Ted",
""
]
] | The following issue is raised and discussed; when do families of foliations by hypersurfaces on a given four dimensional manifold become the null surfaces of some unknown, but to be determined, metric $g_{ab}(x)$? It follows from these results that one can use these surfaces as fundamental variables for GR. |
1909.09752 | Luis Granda | L. N. Granda, G. D. Rojas | Modified Gravity in the framework of holographic dark energy | 24 pages, 5 figures, accepted in MPLA | null | 10.1142/S021773232050025X | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The modified gravity is considered in the framework of the holographic dark
energy. An analysis of the autonomous system, the critical points and their
stability is presented. Unlike the dark energy models based on $f(R)$, it is
found that working in the holographic frame enriches the possibility of
accelerated and matter type points for different cosmological scenarios, making
viable trajectories of successful $f(R)$ models that are not allowed without
the consideration of the holographic framework. The implications for the
Hu-Sawicki model are analyzed.
| [
{
"created": "Sat, 21 Sep 2019 00:51:15 GMT",
"version": "v1"
}
] | 2020-03-18 | [
[
"Granda",
"L. N.",
""
],
[
"Rojas",
"G. D.",
""
]
] | The modified gravity is considered in the framework of the holographic dark energy. An analysis of the autonomous system, the critical points and their stability is presented. Unlike the dark energy models based on $f(R)$, it is found that working in the holographic frame enriches the possibility of accelerated and matter type points for different cosmological scenarios, making viable trajectories of successful $f(R)$ models that are not allowed without the consideration of the holographic framework. The implications for the Hu-Sawicki model are analyzed. |
gr-qc/0101123 | Jose' P. S. Lemos | Alexander B. Balakin, Jose' P. S. Lemos | Singular Behaviour of electric and magnetic fields in dielectric media
in a non-linear gravitational wave background | 16 pages, Latex | Class.Quant.Grav. 18 (2001) 941 | 10.1088/0264-9381/18/5/311 | null | gr-qc | null | Evolution of electric and magnetic fields in dielectric media, driven by the
influence of a strong gravitational wave, is considered for four exactly
integrable models. It is shown that the gravitational wave field gives rise to
new effects and to singular behaviour in the electromagnetic field.
| [
{
"created": "Tue, 30 Jan 2001 20:29:07 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Balakin",
"Alexander B.",
""
],
[
"Lemos",
"Jose' P. S.",
""
]
] | Evolution of electric and magnetic fields in dielectric media, driven by the influence of a strong gravitational wave, is considered for four exactly integrable models. It is shown that the gravitational wave field gives rise to new effects and to singular behaviour in the electromagnetic field. |
gr-qc/0512014 | Rajesh Nayak K | Soumya D. Mohanty and Rajesh K. Nayak | Tomographic approach to resolving the distribution of LISA Galactic
binaries | 13 Pages and 9 figures high resolution figures can be obtains from
http://www.phys.utb.edu/~rajesh/lisa_tomography.pdf | Phys.Rev. D73 (2006) 083006 | 10.1103/PhysRevD.73.083006 | null | gr-qc | null | The space based gravitational wave detector LISA is expected to observe a
large population of Galactic white dwarf binaries whose collective signal is
likely to dominate instrumental noise at observational frequencies in the range
10^{-4} to 10^{-3} Hz. The motion of LISA modulates the signal of each binary
in both frequency and amplitude, the exact modulation depending on the source
direction and frequency. Starting with the observed response of one LISA
interferometer and assuming only doppler modulation due to the orbital motion
of LISA, we show how the distribution of the entire binary population in
frequency and sky position can be reconstructed using a tomographic approach.
The method is linear and the reconstruction of a delta function distribution,
corresponding to an isolated binary, yields a point spread function (psf). An
arbitrary distribution and its reconstruction are related via smoothing with
this psf. Exploratory results are reported demonstrating the recovery of binary
sources, in the presence of white Gaussian noise.
| [
{
"created": "Fri, 2 Dec 2005 17:19:57 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Mohanty",
"Soumya D.",
""
],
[
"Nayak",
"Rajesh K.",
""
]
] | The space based gravitational wave detector LISA is expected to observe a large population of Galactic white dwarf binaries whose collective signal is likely to dominate instrumental noise at observational frequencies in the range 10^{-4} to 10^{-3} Hz. The motion of LISA modulates the signal of each binary in both frequency and amplitude, the exact modulation depending on the source direction and frequency. Starting with the observed response of one LISA interferometer and assuming only doppler modulation due to the orbital motion of LISA, we show how the distribution of the entire binary population in frequency and sky position can be reconstructed using a tomographic approach. The method is linear and the reconstruction of a delta function distribution, corresponding to an isolated binary, yields a point spread function (psf). An arbitrary distribution and its reconstruction are related via smoothing with this psf. Exploratory results are reported demonstrating the recovery of binary sources, in the presence of white Gaussian noise. |
1601.00156 | Diego Rubiera-Garcia | Gonzalo J. Olmo and Diego Rubiera-Garcia | Geons as wormholes of modified gravity | 6 pages; Contribution to the proceedings of "The Fourtheenth Marcel
Grossmann Meeting on General Relativity", University of Rome "La Sapienza",
Rome, July 12-18, 2015, based on an invited talk delivered at the AT3
parallel session | null | null | IFIC/16-57 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Wormholes may arise as solutions of extensions of General Relativity without
violation of the energy conditions. Working in a Palatini approach we consider
classical geometries supporting such wormholes. It is shown that the resulting
space-times represent explicit realizations of the concept of geon introduced
by Wheeler, interpreted as self-consistent bodies generated by an
electromagnetic field without sources.
| [
{
"created": "Sat, 2 Jan 2016 09:46:29 GMT",
"version": "v1"
}
] | 2016-07-25 | [
[
"Olmo",
"Gonzalo J.",
""
],
[
"Rubiera-Garcia",
"Diego",
""
]
] | Wormholes may arise as solutions of extensions of General Relativity without violation of the energy conditions. Working in a Palatini approach we consider classical geometries supporting such wormholes. It is shown that the resulting space-times represent explicit realizations of the concept of geon introduced by Wheeler, interpreted as self-consistent bodies generated by an electromagnetic field without sources. |
2003.04568 | Sudan Hansraj | Sudan Hansraj, Megandhren Govender, Lushen Moodly and Ksh. Newton
Singh | Strange stars in the framework of higher curvature gravity | 20 Pages, 15 figures, 1 table | null | null | null | gr-qc astro-ph.IM hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the influence of higher curvature effects on stellar structure and
conclude that the properties of stars are greatly impacted when such terms are
dynamic. In particular the surface gravitational redshift which is connected to
the equation of state and also the mass-radius ratio differs greatly from the
corresponding values in general relativity as evidenced through our empirical
comparisons. A model of a superdense star with strange star equation of state
is constructed within the framework of the Einstein--Gauss--Bonnet theory.
Under these assumptions large classes of solutions are admitted by the field
equations. We isolate a particular class with the ansatz of the Vaidya--Tikekar
superdense star spatial gravitational potential. The model is found to satisfy
elementary requirements for physical applicability and stability. The parameter
values chosen are consistent with observed star models. A significant effect of
the higher curvature terms is to reduce the speed of sound and to drastically
reduce the values of the surface gravitational redshift compared to the
Einstein counterpart. These latter results have implications for
interpretations of observations in relativistic astrophysics which are often
made against the background of the standard general theory of relativity.
| [
{
"created": "Tue, 10 Mar 2020 08:25:02 GMT",
"version": "v1"
},
{
"created": "Mon, 20 Apr 2020 13:40:19 GMT",
"version": "v2"
},
{
"created": "Fri, 3 Jul 2020 08:12:03 GMT",
"version": "v3"
},
{
"created": "Mon, 6 Jul 2020 11:19:11 GMT",
"version": "v4"
},
{
"cre... | 2021-08-17 | [
[
"Hansraj",
"Sudan",
""
],
[
"Govender",
"Megandhren",
""
],
[
"Moodly",
"Lushen",
""
],
[
"Singh",
"Ksh. Newton",
""
]
] | We study the influence of higher curvature effects on stellar structure and conclude that the properties of stars are greatly impacted when such terms are dynamic. In particular the surface gravitational redshift which is connected to the equation of state and also the mass-radius ratio differs greatly from the corresponding values in general relativity as evidenced through our empirical comparisons. A model of a superdense star with strange star equation of state is constructed within the framework of the Einstein--Gauss--Bonnet theory. Under these assumptions large classes of solutions are admitted by the field equations. We isolate a particular class with the ansatz of the Vaidya--Tikekar superdense star spatial gravitational potential. The model is found to satisfy elementary requirements for physical applicability and stability. The parameter values chosen are consistent with observed star models. A significant effect of the higher curvature terms is to reduce the speed of sound and to drastically reduce the values of the surface gravitational redshift compared to the Einstein counterpart. These latter results have implications for interpretations of observations in relativistic astrophysics which are often made against the background of the standard general theory of relativity. |
1002.5001 | Jonathan McDonald | Jonathan R. McDonald and Warner A. Miller | Coupling Non-Gravitational Fields with Simplicial Spacetimes | 10 pages, no figures, Latex, fixed typos and minor corrections. | Class. Quantum Grav.27:095011,2010 | 10.1088/0264-9381/27/9/095011 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The inclusion of source terms in discrete gravity is a long-standing problem.
Providing a consistent coupling of source to the lattice in Regge Calculus (RC)
yields a robust unstructured spacetime mesh applicable to both numerical
relativity and quantum gravity. RC provides a particularly insightful approach
to this problem with its purely geometric representation of spacetime. The
simplicial building blocks of RC enable us to represent all matter and fields
in a coordinate-free manner. We provide an interpretation of RC as a discrete
exterior calculus framework into which non-gravitational fields naturally
couple with the simplicial lattice. Using this approach we obtain a consistent
mapping of the continuum action for non-gravitational fields to the Regge
lattice. In this paper we apply this framework to scalar, vector and tensor
fields. In particular we reconstruct the lattice action for (1) the scalar
field, (2) Maxwell field tensor and (3) Dirac particles. The straightforward
application of our discretization techniques to these three fields demonstrates
a universal implementation of coupling source to the lattice in Regge calculus.
| [
{
"created": "Fri, 26 Feb 2010 14:47:28 GMT",
"version": "v1"
},
{
"created": "Wed, 7 Apr 2010 10:37:53 GMT",
"version": "v2"
}
] | 2015-03-13 | [
[
"McDonald",
"Jonathan R.",
""
],
[
"Miller",
"Warner A.",
""
]
] | The inclusion of source terms in discrete gravity is a long-standing problem. Providing a consistent coupling of source to the lattice in Regge Calculus (RC) yields a robust unstructured spacetime mesh applicable to both numerical relativity and quantum gravity. RC provides a particularly insightful approach to this problem with its purely geometric representation of spacetime. The simplicial building blocks of RC enable us to represent all matter and fields in a coordinate-free manner. We provide an interpretation of RC as a discrete exterior calculus framework into which non-gravitational fields naturally couple with the simplicial lattice. Using this approach we obtain a consistent mapping of the continuum action for non-gravitational fields to the Regge lattice. In this paper we apply this framework to scalar, vector and tensor fields. In particular we reconstruct the lattice action for (1) the scalar field, (2) Maxwell field tensor and (3) Dirac particles. The straightforward application of our discretization techniques to these three fields demonstrates a universal implementation of coupling source to the lattice in Regge calculus. |
2006.16810 | Angelo E. S. Hartmann | M. Novello and A. E. S. Hartmann | From weak interaction to gravity | 18 pages, extended version that includes arXiv:2007.01140 | Int. J. Mod. Phys. A 36, 7 (2021) 21500051 | 10.1142/S0217751X21500512 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We follow an old suggestion made by Stueckelberg that there exists an
intimate connection between weak interaction and gravity, symbolized by the
relationship between the Fermi and Newton\rq s constants. We analyze the
hypothesis that the effect of matter upon the metric that represents
gravitational interaction in General Relativity is an effective one. This leads
us to consider gravitation to be the result of the interaction of two neutral
spinorial fields (G-neutrinos) $ \Psi_{g}$ and $ \Omega_{g}$ with all kinds of
matter and energy. We present three examples with only one G-neutrino: two
static and spherically symmetric configurations and a cosmological framework
for an isotropic dynamical universe. Without self-interaction, the associated
effective geometry is precisely the Schwarzschild metric. On the other hand, a
self-interacting G-neutrino generates a new gravitational black-hole.
| [
{
"created": "Mon, 29 Jun 2020 06:25:14 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Jul 2020 20:32:03 GMT",
"version": "v2"
},
{
"created": "Wed, 21 Apr 2021 15:58:28 GMT",
"version": "v3"
}
] | 2021-12-20 | [
[
"Novello",
"M.",
""
],
[
"Hartmann",
"A. E. S.",
""
]
] | We follow an old suggestion made by Stueckelberg that there exists an intimate connection between weak interaction and gravity, symbolized by the relationship between the Fermi and Newton\rq s constants. We analyze the hypothesis that the effect of matter upon the metric that represents gravitational interaction in General Relativity is an effective one. This leads us to consider gravitation to be the result of the interaction of two neutral spinorial fields (G-neutrinos) $ \Psi_{g}$ and $ \Omega_{g}$ with all kinds of matter and energy. We present three examples with only one G-neutrino: two static and spherically symmetric configurations and a cosmological framework for an isotropic dynamical universe. Without self-interaction, the associated effective geometry is precisely the Schwarzschild metric. On the other hand, a self-interacting G-neutrino generates a new gravitational black-hole. |
gr-qc/9905078 | Francisco Turrubiates | Maciej Przanowski, Sebastian Formanski and Francisco J.Turrubiates | Nonlinear Graviton as a Limit of sl(N;C) Chiral Fields as N--> infty | 9 pages, LaTeX file, no figures, version published in Mod. Phys.
Lett. A | Mod.Phys.Lett. A13 (1998) 3193-3200 | 10.1142/S0217732398003405 | CINVESTAV-FIS-31/98 | gr-qc | null | An example of a sequence of the sl(N;C) chiral fields, for N$\geq 2$, tending
to the complex heavenly metric (nonlinear graviton) of the type [4]x[-] when N
--> infinity is given.
| [
{
"created": "Thu, 20 May 1999 15:29:31 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Przanowski",
"Maciej",
""
],
[
"Formanski",
"Sebastian",
""
],
[
"Turrubiates",
"Francisco J.",
""
]
] | An example of a sequence of the sl(N;C) chiral fields, for N$\geq 2$, tending to the complex heavenly metric (nonlinear graviton) of the type [4]x[-] when N --> infinity is given. |
0908.3885 | Timir Datta | Timir Datta and Ming Yin | Do Quantum Systems Break The Equivalence Principle? | 14 PDF pages including 5 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational response of real objects is a fascinating topic. Einstein
formalized the Galileo-Newton ideas of equality of free falls into complete
physical equivalence or the Principle of Equivalence [Albert Einstein, The
meaning of Relativity, 5 ed. Princeton, (1921)]. However, in this article we
point out that in a gravitational field, g, the bulk response of an
electrically neutral but atomistic test mass is model dependant. Depending on
the particular quantum approximation scheme, opposing results for the gravity
induced (electric) polarization P have been reported. For instance, P is small
and oriented anti-parallel to g, if the deformations of the positive background
lattice is neglected But, it is about ~ 100,1000 times larger and opposite in
direction in the elastic lattice approximation. Hence, the elastic model
contradicts reports of polarization in accelerated metals [Richard C. Tolman &
T.Dale Stewart, Phys Rev 28, 794 (1926); G. F. Moorhead & G. I. Opat, Class.
Quant. Grav, 13, 3129 (1996)]. Surprisingly, the rigid system is consistent
with EP but the elastic system breaks EP. Here the historical literature is
surveyed and some implications are outlined.
| [
{
"created": "Wed, 26 Aug 2009 19:29:02 GMT",
"version": "v1"
}
] | 2009-08-27 | [
[
"Datta",
"Timir",
""
],
[
"Yin",
"Ming",
""
]
] | Gravitational response of real objects is a fascinating topic. Einstein formalized the Galileo-Newton ideas of equality of free falls into complete physical equivalence or the Principle of Equivalence [Albert Einstein, The meaning of Relativity, 5 ed. Princeton, (1921)]. However, in this article we point out that in a gravitational field, g, the bulk response of an electrically neutral but atomistic test mass is model dependant. Depending on the particular quantum approximation scheme, opposing results for the gravity induced (electric) polarization P have been reported. For instance, P is small and oriented anti-parallel to g, if the deformations of the positive background lattice is neglected But, it is about ~ 100,1000 times larger and opposite in direction in the elastic lattice approximation. Hence, the elastic model contradicts reports of polarization in accelerated metals [Richard C. Tolman & T.Dale Stewart, Phys Rev 28, 794 (1926); G. F. Moorhead & G. I. Opat, Class. Quant. Grav, 13, 3129 (1996)]. Surprisingly, the rigid system is consistent with EP but the elastic system breaks EP. Here the historical literature is surveyed and some implications are outlined. |
2204.03993 | Irene Fiori | Nicolas Arnaud, Rosario De Rosa, Francesco Di Renzo, Irene Fiori,
Carlo Giunchi, Kamiel Janssens, Alessandro Longo, Marco Olivieri, Federico
Paoletti, Paolo Ruggi, Maria Concetta Tringali | External environmental noise influences on Virgo during O3 | contribution to the 2021 Gravitation session of the 55th Rencontres
de Moriond | null | null | null | gr-qc physics.ins-det | http://creativecommons.org/licenses/by/4.0/ | Sources of geophysical noise, such as wind, sea waves and earthquakes, can
have an impact on gravitational wave interferometers causing sensitivity
worsening and gaps in data taking. During the 1-year long O3 run (April 1st
2019 to March 27th 2020), the Virgo Collaboration collected a statistically
significant dataset to study the response of the detector to a variety of
environmental conditions. We used these data to correlate environmental
parameters to global detector performance, such as observation range, duty
cycle and control losses. Where possible, we identified weaknesses in the
detector and we elaborated strategies to improve Virgo robustness against
external disturbances for the next run O4, planned to start in summer 2022. In
this article we present preliminary results of this study.
| [
{
"created": "Fri, 8 Apr 2022 10:54:52 GMT",
"version": "v1"
}
] | 2022-04-11 | [
[
"Arnaud",
"Nicolas",
""
],
[
"De Rosa",
"Rosario",
""
],
[
"Di Renzo",
"Francesco",
""
],
[
"Fiori",
"Irene",
""
],
[
"Giunchi",
"Carlo",
""
],
[
"Janssens",
"Kamiel",
""
],
[
"Longo",
"Alessandro",
""
],... | Sources of geophysical noise, such as wind, sea waves and earthquakes, can have an impact on gravitational wave interferometers causing sensitivity worsening and gaps in data taking. During the 1-year long O3 run (April 1st 2019 to March 27th 2020), the Virgo Collaboration collected a statistically significant dataset to study the response of the detector to a variety of environmental conditions. We used these data to correlate environmental parameters to global detector performance, such as observation range, duty cycle and control losses. Where possible, we identified weaknesses in the detector and we elaborated strategies to improve Virgo robustness against external disturbances for the next run O4, planned to start in summer 2022. In this article we present preliminary results of this study. |
1012.4039 | Thomas Sotiriou | Thomas P. Sotiriou, Baojiu Li, John D. Barrow | Generalizations of teleparallel gravity and local Lorentz symmetry | 6 pages; v2: minor edits to match published version | Phys.Rev.D83:104030,2011 | 10.1103/PhysRevD.83.104030 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyze the relation between teleparallelism and local Lorentz invariance.
We show that generic modifications of the teleparallel equivalent to general
relativity will not respect local Lorentz symmetry. We clarify the reasons for
this and explain why the situation is different in general relativity. We give
a prescription for constructing teleparallel equivalents for known theories. We
also explicitly consider a recently proposed class of generalized teleparallel
theories, called f(T) theories of gravity, and show why restoring local Lorentz
symmetry in such theories cannot lead to sensible dynamics, even if one gives
up teleparallelism.
| [
{
"created": "Sat, 18 Dec 2010 00:05:00 GMT",
"version": "v1"
},
{
"created": "Thu, 19 May 2011 07:59:57 GMT",
"version": "v2"
}
] | 2011-05-25 | [
[
"Sotiriou",
"Thomas P.",
""
],
[
"Li",
"Baojiu",
""
],
[
"Barrow",
"John D.",
""
]
] | We analyze the relation between teleparallelism and local Lorentz invariance. We show that generic modifications of the teleparallel equivalent to general relativity will not respect local Lorentz symmetry. We clarify the reasons for this and explain why the situation is different in general relativity. We give a prescription for constructing teleparallel equivalents for known theories. We also explicitly consider a recently proposed class of generalized teleparallel theories, called f(T) theories of gravity, and show why restoring local Lorentz symmetry in such theories cannot lead to sensible dynamics, even if one gives up teleparallelism. |
gr-qc/0412064 | Kjell Rosquist | Kjell Rosquist | Gravitationally induced electromagnetism at the Compton scale | 11 pages, 3 figures: revised version published in Class. Quantum
Grav. 23 (2006) 3111-3122; Conclusions unchanged | Class.Quant.Grav.23:3111-3122,2006 | 10.1088/0264-9381/23/9/021 | null | gr-qc astro-ph hep-ph hep-th nucl-th | null | It is shown that Einstein gravity tends to modify the electric and magnetic
fields appreciably at distances of the order of the Compton wavelength. At that
distance the gravitational field becomes spin dominated rather than mass
dominated. The gravitational field couples to the electromagnetic field via the
Einstein-Maxwell equations which in the simplest model causes the electrostatic
field of charged spinning particles to acquire an oblate structure relative to
the spin direction. For electrons and protons, a pure Coulomb field is
therefore likely to be incompatible with general relativity at the Compton
scale. In the simplest model, the magnetic dipole corresponds to the Dirac
g-factor, g=2. Also, it follows from the form of the electric field that the
electric dipole moment vanishes, in agreement with current experimental limits
for the electron. Quantitatively, the classical Einstein-Maxwell theory
predicts the magnetic and electric dipoles of the electron to an accuracy of
about one part in 10^{-3} or better. Going to the next multipole order, one
finds that the first non-vanishing higher multipole is the electric quadrupole
moment which is predicted to be -124 barn for the electron. Any non-zero value
of the electric quadrupole moment for the electron or the proton would be a
clear sign of curvature due to the implied violation of rotation invariance.
There is also a possible spherical modification of the Coulomb force
proportional to r^{-4}. However, the size of this effect is well below current
experimental limits. The corrections to the hydrogen spectrum are expected to
be small but possibly detectable.
| [
{
"created": "Tue, 14 Dec 2004 13:32:04 GMT",
"version": "v1"
},
{
"created": "Mon, 20 Dec 2004 08:06:58 GMT",
"version": "v2"
},
{
"created": "Mon, 10 Apr 2006 13:32:52 GMT",
"version": "v3"
}
] | 2014-11-17 | [
[
"Rosquist",
"Kjell",
""
]
] | It is shown that Einstein gravity tends to modify the electric and magnetic fields appreciably at distances of the order of the Compton wavelength. At that distance the gravitational field becomes spin dominated rather than mass dominated. The gravitational field couples to the electromagnetic field via the Einstein-Maxwell equations which in the simplest model causes the electrostatic field of charged spinning particles to acquire an oblate structure relative to the spin direction. For electrons and protons, a pure Coulomb field is therefore likely to be incompatible with general relativity at the Compton scale. In the simplest model, the magnetic dipole corresponds to the Dirac g-factor, g=2. Also, it follows from the form of the electric field that the electric dipole moment vanishes, in agreement with current experimental limits for the electron. Quantitatively, the classical Einstein-Maxwell theory predicts the magnetic and electric dipoles of the electron to an accuracy of about one part in 10^{-3} or better. Going to the next multipole order, one finds that the first non-vanishing higher multipole is the electric quadrupole moment which is predicted to be -124 barn for the electron. Any non-zero value of the electric quadrupole moment for the electron or the proton would be a clear sign of curvature due to the implied violation of rotation invariance. There is also a possible spherical modification of the Coulomb force proportional to r^{-4}. However, the size of this effect is well below current experimental limits. The corrections to the hydrogen spectrum are expected to be small but possibly detectable. |
1212.3698 | Shan Bai | Shan Bai, Niall \'O Murchadha | Scaling up the extrinsic curvature in gravitational initial data | 9 pages, 8 figures | Physical Review D85, 044028 (2012) | 10.1103/PhysRevD.85.044028 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Vacuum solutions to the Einstein equations can be viewed as the interplay
between the geometry and the gravitational wave energy content. The constraints
on initial data reflect this interaction. We assume we are looking at
cosmological solutions to the Einstein equations so we assume that the 3-space
is compact, without boundary. In this article we investigate, using both
analytic and numerical techniques, what happens when the extrinsic curvature is
increased while the background geometry is held fixed. This is equivalent to
trying to magnify the local gravitational wave kinetic energy on an unchanged
background. We find that the physical intrinsic curvature does not blow up.
Rather the local volume of space expands to accommodate this attempt to
increase the kinetic energy.
| [
{
"created": "Sat, 15 Dec 2012 16:05:44 GMT",
"version": "v1"
}
] | 2015-06-12 | [
[
"Bai",
"Shan",
""
],
[
"Murchadha",
"Niall Ó",
""
]
] | Vacuum solutions to the Einstein equations can be viewed as the interplay between the geometry and the gravitational wave energy content. The constraints on initial data reflect this interaction. We assume we are looking at cosmological solutions to the Einstein equations so we assume that the 3-space is compact, without boundary. In this article we investigate, using both analytic and numerical techniques, what happens when the extrinsic curvature is increased while the background geometry is held fixed. This is equivalent to trying to magnify the local gravitational wave kinetic energy on an unchanged background. We find that the physical intrinsic curvature does not blow up. Rather the local volume of space expands to accommodate this attempt to increase the kinetic energy. |
gr-qc/9806087 | Edward Seidel | Edward Seidel | The Synergy between Numerical and Perturbative Approaches to Black Holes | 18 pages, 7 figures, To appear in "On the Black Hole Trail" eds. Bala
Iyer and Biplab Bhawal (Kluwer) | null | null | AEI-066 | gr-qc | null | I describe approaches to the study of black hole spacetimes via numerical
relativity. After a brief review of the basic formalisms and techniques used in
numerical black hole simulations, I discuss a series of calculations from
axisymmetry to full 3D that can be seen as stepping stones to simulations of
the full 3D coalescence of two black holes. In particular, I emphasize the
interplay between perturbation theory and numerical simulation that build both
confidence in present results and tools to aid and to interpret results of
future simulations of black hole coalescence.
| [
{
"created": "Tue, 23 Jun 1998 08:55:55 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Seidel",
"Edward",
""
]
] | I describe approaches to the study of black hole spacetimes via numerical relativity. After a brief review of the basic formalisms and techniques used in numerical black hole simulations, I discuss a series of calculations from axisymmetry to full 3D that can be seen as stepping stones to simulations of the full 3D coalescence of two black holes. In particular, I emphasize the interplay between perturbation theory and numerical simulation that build both confidence in present results and tools to aid and to interpret results of future simulations of black hole coalescence. |
1202.5972 | Carlos Kozameh | Carlos N. Kozameh, Gonzalo Quiroga | Spin and Center of Mass in Axially Symmetric Einstein-Maxwell Spacetimes | 20 pages | null | 10.1088/0264-9381/29/23/235006 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We give a definition and derive the equations of motion for the center of
mass and angular momentum of an axially symmetric, isolated system that emits
gravitational and electromagnetic radiation. A central feature of this
formulation is the use of Newman-Unti cuts at null infinity that are generated
by worldlines of the spacetime. We analyze some consequences of the results and
comment on the generalization of this work to general asymptotically flat
spacetimes.
| [
{
"created": "Mon, 27 Feb 2012 15:31:58 GMT",
"version": "v1"
}
] | 2015-06-04 | [
[
"Kozameh",
"Carlos N.",
""
],
[
"Quiroga",
"Gonzalo",
""
]
] | We give a definition and derive the equations of motion for the center of mass and angular momentum of an axially symmetric, isolated system that emits gravitational and electromagnetic radiation. A central feature of this formulation is the use of Newman-Unti cuts at null infinity that are generated by worldlines of the spacetime. We analyze some consequences of the results and comment on the generalization of this work to general asymptotically flat spacetimes. |
gr-qc/0003028 | Esposito Giampiero | Giampiero Esposito and Cosimo Stornaiolo | On the ADM Equations for General Relativity | 10 pages, plain Tex. The final version contains new original
calculations | Found.Phys.Lett. 13 (2000) 279-288 | null | DSF preprint 2000/8 | gr-qc | null | The Arnowitt-Deser-Misner (ADM) evolution equations for the induced metric
and the extrinsic-curvature tensor of the spacelike surfaces which foliate the
space-time manifold in canonical general relativity are a first-order system of
quasi-linear partial differential equations, supplemented by the constraint
equations. Such equations are here mapped into another first-order system. In
particular, an evolution equation for the trace of the extrinsic-curvature
tensor K is obtained whose solution is related to a discrete spectral
resolution of a three-dimensional elliptic operator P of Laplace type.
Interestingly, all nonlinearities of the original equations give rise to the
potential term in P. An example of this construction is given in the case of a
closed Friedmann-Lemaitre-Robertson-Walker universe. Eventually, the ADM
equations are re-expressed as a coupled first-order system for the induced
metric and the trace-free part of K. Such a system is written in a form which
clarifies how a set of first-order differential operators and their inverses,
jointly with spectral resolutions of operators of Laplace type, contribute to
solving, at least in principle, the original ADM system.
| [
{
"created": "Wed, 8 Mar 2000 09:37:19 GMT",
"version": "v1"
},
{
"created": "Wed, 5 Apr 2000 06:25:37 GMT",
"version": "v2"
},
{
"created": "Tue, 2 May 2000 07:14:14 GMT",
"version": "v3"
}
] | 2007-05-23 | [
[
"Esposito",
"Giampiero",
""
],
[
"Stornaiolo",
"Cosimo",
""
]
] | The Arnowitt-Deser-Misner (ADM) evolution equations for the induced metric and the extrinsic-curvature tensor of the spacelike surfaces which foliate the space-time manifold in canonical general relativity are a first-order system of quasi-linear partial differential equations, supplemented by the constraint equations. Such equations are here mapped into another first-order system. In particular, an evolution equation for the trace of the extrinsic-curvature tensor K is obtained whose solution is related to a discrete spectral resolution of a three-dimensional elliptic operator P of Laplace type. Interestingly, all nonlinearities of the original equations give rise to the potential term in P. An example of this construction is given in the case of a closed Friedmann-Lemaitre-Robertson-Walker universe. Eventually, the ADM equations are re-expressed as a coupled first-order system for the induced metric and the trace-free part of K. Such a system is written in a form which clarifies how a set of first-order differential operators and their inverses, jointly with spectral resolutions of operators of Laplace type, contribute to solving, at least in principle, the original ADM system. |
gr-qc/9807075 | David Wiltshire | N. Kontoleon and D.L. Wiltshire | Operator ordering and consistency of the wavefunction of the Universe | 9 pages, epsf, revTeX-3.1, 1 figure. In revised version (v2) a new
section etc with additional arguments increases the length of paper by 3
pages of Physical Review; several references added. v3: small typos fixed | Phys.Rev. D59 (1999) 063513 | 10.1103/PhysRevD.59.063513 | ADP-98-43/M71 | gr-qc astro-ph hep-th | null | We demonstrate in the context of the minisuperspace model consisting of a
closed Friedmann-Robertson-Walker universe coupled to a scalar field that
Vilenkin's tunneling wavefunction can only be consistently defined for
particular choices of operator ordering in the Wheeler-DeWitt equation. The
requirement of regularity of the wavefunction has the particular consequence
that the probability amplitude, which has been used previously in the
literature in discussions of issues such as the prediction of inflation, is
likewise ill-defined for certain choices of operator ordering with Vilenkin's
boundary condition. By contrast, the Hartle-Hawking no-boundary wavefunction
can be consistently defined within these models, independently of operator
ordering. The significance of this result is discussed within the context of
the debate about the predictions of semiclassical quantum cosmology. In
particular, it is argued that inflation cannot be confidently regarded as a
"prediction" of the tunneling wavefunction, for reasons similar to those
previously invoked in the case of the no-boundary wavefunction. A synthesis of
the no-boundary and tunneling approaches is argued for.
| [
{
"created": "Tue, 28 Jul 1998 17:22:29 GMT",
"version": "v1"
},
{
"created": "Thu, 24 Dec 1998 06:43:44 GMT",
"version": "v2"
},
{
"created": "Mon, 1 Mar 1999 02:21:37 GMT",
"version": "v3"
}
] | 2009-10-31 | [
[
"Kontoleon",
"N.",
""
],
[
"Wiltshire",
"D. L.",
""
]
] | We demonstrate in the context of the minisuperspace model consisting of a closed Friedmann-Robertson-Walker universe coupled to a scalar field that Vilenkin's tunneling wavefunction can only be consistently defined for particular choices of operator ordering in the Wheeler-DeWitt equation. The requirement of regularity of the wavefunction has the particular consequence that the probability amplitude, which has been used previously in the literature in discussions of issues such as the prediction of inflation, is likewise ill-defined for certain choices of operator ordering with Vilenkin's boundary condition. By contrast, the Hartle-Hawking no-boundary wavefunction can be consistently defined within these models, independently of operator ordering. The significance of this result is discussed within the context of the debate about the predictions of semiclassical quantum cosmology. In particular, it is argued that inflation cannot be confidently regarded as a "prediction" of the tunneling wavefunction, for reasons similar to those previously invoked in the case of the no-boundary wavefunction. A synthesis of the no-boundary and tunneling approaches is argued for. |
1805.03069 | Kazem Rezazadeh | K. Fahimi, K. Karami, S. Asadzadeh, K. Rezazadeh | Structure formation in clustering DBI dark energy model with constant
sound speed | 13 pages, 9 figures | MNRAS 481, 2393 (2018) | 10.1093/mnras/sty2416 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Within the framework of DBI non-canonical scalar field model of dark energy,
we study the growth of dark matter perturbations in the both linear and
non-linear regimes. In our DBI model, we consider the anti-de Sitter warp
factor $f(\phi)=f_0\, \phi^{-4}$ with constant $f_0>0$ and assume the DBI dark
energy to be clustered and its sound speed $c_s$ to be constant. For a
spatially flat FRW universe filled with pressureless dark matter and DBI dark
energy, we first obtain the evolutionary behaviors of the background
quantities. Our results show that in our DBI model, the universe starts from a
matter dominated epoch and approaches to the de Sitter universe at late times,
as expected. Also the DBI potential behaves like the power law one
$V(\phi)\propto \phi^n$.
In addition, we use the Pseudo-Newtonian formalism to obtain the growth
factor of dark matter perturbations in the linear regime. We conclude that for
smaller $c_s$ (or $f_0$), the growth factor of dark matter is smaller for
clustering DBI model compared to the homogeneous one. In the following, in the
non-linear regime based on the spherical collapse model, we obtain the linear
overdensity $\delta_c(z_c)$, the virial overdensity $\Delta_{\rm vir}(z_c)$,
overdensity at the turn around $\zeta(z_c)$ and the rate of expansion of
collapsed region $h_{\rm ta}(z)$. We point out that for the smaller $c_s$ (or
$\tilde{f}_0$), the values of $\delta_c(z_c)$, $\Delta_{\rm vir}(z_c)$,
$\zeta(z_c)$ and $h_{\rm ta}(z)$ in non-clustering DBI models deviate more than
the $\Lambda$CDM compared to the clustering DBI. Finally, with the help of
spherical collapse parameters we calculated the relative number density of halo
objects above a given mass and conclude that the differences between clustering
and homogeneous DBI models are more pronounced for higher-mass halos at high
redshift.
| [
{
"created": "Sun, 6 May 2018 11:47:08 GMT",
"version": "v1"
},
{
"created": "Mon, 29 Oct 2018 13:14:38 GMT",
"version": "v2"
}
] | 2018-10-30 | [
[
"Fahimi",
"K.",
""
],
[
"Karami",
"K.",
""
],
[
"Asadzadeh",
"S.",
""
],
[
"Rezazadeh",
"K.",
""
]
] | Within the framework of DBI non-canonical scalar field model of dark energy, we study the growth of dark matter perturbations in the both linear and non-linear regimes. In our DBI model, we consider the anti-de Sitter warp factor $f(\phi)=f_0\, \phi^{-4}$ with constant $f_0>0$ and assume the DBI dark energy to be clustered and its sound speed $c_s$ to be constant. For a spatially flat FRW universe filled with pressureless dark matter and DBI dark energy, we first obtain the evolutionary behaviors of the background quantities. Our results show that in our DBI model, the universe starts from a matter dominated epoch and approaches to the de Sitter universe at late times, as expected. Also the DBI potential behaves like the power law one $V(\phi)\propto \phi^n$. In addition, we use the Pseudo-Newtonian formalism to obtain the growth factor of dark matter perturbations in the linear regime. We conclude that for smaller $c_s$ (or $f_0$), the growth factor of dark matter is smaller for clustering DBI model compared to the homogeneous one. In the following, in the non-linear regime based on the spherical collapse model, we obtain the linear overdensity $\delta_c(z_c)$, the virial overdensity $\Delta_{\rm vir}(z_c)$, overdensity at the turn around $\zeta(z_c)$ and the rate of expansion of collapsed region $h_{\rm ta}(z)$. We point out that for the smaller $c_s$ (or $\tilde{f}_0$), the values of $\delta_c(z_c)$, $\Delta_{\rm vir}(z_c)$, $\zeta(z_c)$ and $h_{\rm ta}(z)$ in non-clustering DBI models deviate more than the $\Lambda$CDM compared to the clustering DBI. Finally, with the help of spherical collapse parameters we calculated the relative number density of halo objects above a given mass and conclude that the differences between clustering and homogeneous DBI models are more pronounced for higher-mass halos at high redshift. |
0912.4862 | Kirill Bronnikov | K.A. Bronnikov, S.G. Rubin, I.V. Svadkovsky | Multidimensional world, inflation and modern acceleration | 7 two-column revtex pages, 2 figures | Phys.Rev.D81:084010,2010 | 10.1103/PhysRevD.81.084010 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Starting from pure multidimensional gravity with curvature-nonlinear terms
but no matter fields in the initial action, we obtain a cosmological model with
two effective scalar fields related to the size of two extra factor spaces. The
model includes both an early inflationary stage and that of modern accelerated
expansion and satisfies the observational data. There are no small parameters;
the effective inflaton mass depends on the initial conditions which explain its
small value as compared to the Planck mass. At the modern stage, the size of
extra dimensions slowly increases, therefore this model predicts drastic
changes in the physical laws of our Universe in the remote future.
| [
{
"created": "Thu, 24 Dec 2009 13:52:15 GMT",
"version": "v1"
}
] | 2010-04-21 | [
[
"Bronnikov",
"K. A.",
""
],
[
"Rubin",
"S. G.",
""
],
[
"Svadkovsky",
"I. V.",
""
]
] | Starting from pure multidimensional gravity with curvature-nonlinear terms but no matter fields in the initial action, we obtain a cosmological model with two effective scalar fields related to the size of two extra factor spaces. The model includes both an early inflationary stage and that of modern accelerated expansion and satisfies the observational data. There are no small parameters; the effective inflaton mass depends on the initial conditions which explain its small value as compared to the Planck mass. At the modern stage, the size of extra dimensions slowly increases, therefore this model predicts drastic changes in the physical laws of our Universe in the remote future. |
gr-qc/0701125 | Hernando Quevedo | Francisco J. Hernandez and Hernando Quevedo | Entropy and anisotropy | To be published in Gen.Rel.Grav. (Obregon's Festschrift) | Gen.Rel.Grav.39:1297-1309,2007 | 10.1007/s10714-007-0456-9 | null | gr-qc | null | We address the problem of defining the concept of entropy for anisotropic
cosmological models. In particular, we analyze for the Bianchi I and V models
the entropy which follows from postulating the validity of the laws of standard
thermodynamics in cosmology. Moreover, we analyze the Cardy-Verlinde
construction of entropy and show that it cannot be associated with the one
following from relativistic thermodynamics.
| [
{
"created": "Tue, 23 Jan 2007 01:00:26 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Hernandez",
"Francisco J.",
""
],
[
"Quevedo",
"Hernando",
""
]
] | We address the problem of defining the concept of entropy for anisotropic cosmological models. In particular, we analyze for the Bianchi I and V models the entropy which follows from postulating the validity of the laws of standard thermodynamics in cosmology. Moreover, we analyze the Cardy-Verlinde construction of entropy and show that it cannot be associated with the one following from relativistic thermodynamics. |
gr-qc/0401041 | Gamal Nashed | Gamal G.L. Nashed | Reissner Nordstr$\ddot{o}$m solutions and Energy in teleparallel theory | 12 pages tex file | Mod.Phys.Lett.A21:2241-2250,2006 | 10.1142/S0217732306020445 | null | gr-qc | null | We give three different spherically symmetric spacetimes for the coupled
gravitational and electromagnetic fields with charged source in the tetrad
theory of gravitation. One of these, contains an arbitrary function and
generates the others. These spacetimes give the Reissner Nordstr$\ddot{o}$m
metric black hole. We then, calculated the energy associated with these
spacetimes using the superpotential method. We find that unless the time-space
components of the tetrad field go to zero faster than ${1/\sqrt{r}}$ at
infinity, one gets different results for the energy.
| [
{
"created": "Sun, 11 Jan 2004 06:00:23 GMT",
"version": "v1"
},
{
"created": "Thu, 5 Jan 2006 08:37:25 GMT",
"version": "v2"
}
] | 2010-11-05 | [
[
"Nashed",
"Gamal G. L.",
""
]
] | We give three different spherically symmetric spacetimes for the coupled gravitational and electromagnetic fields with charged source in the tetrad theory of gravitation. One of these, contains an arbitrary function and generates the others. These spacetimes give the Reissner Nordstr$\ddot{o}$m metric black hole. We then, calculated the energy associated with these spacetimes using the superpotential method. We find that unless the time-space components of the tetrad field go to zero faster than ${1/\sqrt{r}}$ at infinity, one gets different results for the energy. |
1307.7685 | Francois Foucart | Francois Foucart, Luisa Buchman, Matthew D. Duez, Michael Grudich,
Lawrence E. Kidder, Ilana MacDonald, Abdul Mroue, Harald P. Pfeiffer, Mark A.
Scheel and Bela Szilagyi | First direct comparison of non-disrupting neutron star-black hole and
binary black hole merger simulations | 13 pages, 9 figures | null | 10.1103/PhysRevD.88.064017 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present the first direct comparison of numerical simulations of neutron
star-black hole and black hole-black hole mergers in full general relativity.
We focus on a configuration with non spinning objects and within the most
likely range of mass ratio for neutron star-black hole systems (q=6). In this
region of the parameter space, the neutron star is not tidally disrupted prior
to merger, and we show that the two types of mergers appear remarkably similar.
The effect of the presence of a neutron star on the gravitational wave signal
is not only undetectable by the next generation of gravitational wave
detectors, but also too small to be measured in the numerical simulations: even
the plunge, merger and ringdown signals appear in perfect agreement for both
types of binaries. The characteristics of the post-merger remnants are equally
similar, with the masses of the final black holes agreeing within dM< 5
10^{-4}M_BH and their spins within da< 10^{-3}M_BH. The rate of periastron
advance in the mixed binary agrees with previously published binary black hole
results, and we use the inspiral waveforms to place constraints on the accuracy
of our numerical simulations independent of algorithmic choices made for each
type of binary. Overall, our results indicate that non-disrupting neutron
star-black hole mergers are exceptionally well modeled by black hole-black hole
mergers, and that given the absence of mass ejection, accretion disk formation,
or differences in the gravitational wave signals, only electromagnetic
precursors could prove the presence of a neutron star in low-spin systems of
total mass ~10Msun, at least until the advent of gravitational wave detectors
with a sensitivity comparable to that of the proposed Einstein Telescope.
| [
{
"created": "Mon, 29 Jul 2013 19:11:34 GMT",
"version": "v1"
}
] | 2013-09-18 | [
[
"Foucart",
"Francois",
""
],
[
"Buchman",
"Luisa",
""
],
[
"Duez",
"Matthew D.",
""
],
[
"Grudich",
"Michael",
""
],
[
"Kidder",
"Lawrence E.",
""
],
[
"MacDonald",
"Ilana",
""
],
[
"Mroue",
"Abdul",
""
]... | We present the first direct comparison of numerical simulations of neutron star-black hole and black hole-black hole mergers in full general relativity. We focus on a configuration with non spinning objects and within the most likely range of mass ratio for neutron star-black hole systems (q=6). In this region of the parameter space, the neutron star is not tidally disrupted prior to merger, and we show that the two types of mergers appear remarkably similar. The effect of the presence of a neutron star on the gravitational wave signal is not only undetectable by the next generation of gravitational wave detectors, but also too small to be measured in the numerical simulations: even the plunge, merger and ringdown signals appear in perfect agreement for both types of binaries. The characteristics of the post-merger remnants are equally similar, with the masses of the final black holes agreeing within dM< 5 10^{-4}M_BH and their spins within da< 10^{-3}M_BH. The rate of periastron advance in the mixed binary agrees with previously published binary black hole results, and we use the inspiral waveforms to place constraints on the accuracy of our numerical simulations independent of algorithmic choices made for each type of binary. Overall, our results indicate that non-disrupting neutron star-black hole mergers are exceptionally well modeled by black hole-black hole mergers, and that given the absence of mass ejection, accretion disk formation, or differences in the gravitational wave signals, only electromagnetic precursors could prove the presence of a neutron star in low-spin systems of total mass ~10Msun, at least until the advent of gravitational wave detectors with a sensitivity comparable to that of the proposed Einstein Telescope. |
1612.04002 | Miguel Sabido | Javier Chagoya and M. Sabido | Self-Dual Gravity and the Immirzi parameter | 7 pages, no figures, RevTex | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Working in the first order formalism of gravity, we propose an action that
combines the self and anti-self-dual parts of the curvature and comprises all
the diffeomorphism invariant Lagrangians that one can consider in this
formalism. The action that we propose is motivated by (A)dS gauge theories of
gravity. We use this action to derive the (2+1)-dimensional version of the
Immirzi parameter. Our derivation relates explicitly the Immirzi parameter to
the existence of two classically equivalent actions for the description of
gravity in (2+1) dimensions, namely the standard and exotic actions introduced
by Witten in the description of (2+1) gravity as a gauge theory. This relation
had been conjectured previously in the literature, but not derived.
| [
{
"created": "Tue, 13 Dec 2016 02:58:35 GMT",
"version": "v1"
}
] | 2016-12-14 | [
[
"Chagoya",
"Javier",
""
],
[
"Sabido",
"M.",
""
]
] | Working in the first order formalism of gravity, we propose an action that combines the self and anti-self-dual parts of the curvature and comprises all the diffeomorphism invariant Lagrangians that one can consider in this formalism. The action that we propose is motivated by (A)dS gauge theories of gravity. We use this action to derive the (2+1)-dimensional version of the Immirzi parameter. Our derivation relates explicitly the Immirzi parameter to the existence of two classically equivalent actions for the description of gravity in (2+1) dimensions, namely the standard and exotic actions introduced by Witten in the description of (2+1) gravity as a gauge theory. This relation had been conjectured previously in the literature, but not derived. |
gr-qc/0406098 | Vakif Onemli K | V. K. Onemli and R. P. Woodard | Quantum effects can render w<-1 on cosmological scales | 9 pages, references added | Phys.Rev. D70 (2004) 107301 | 10.1103/PhysRevD.70.107301 | LPT-ORSAY 04-47, UFIFT-QG-04-1 | gr-qc astro-ph hep-ph | null | We report on a revision of our previous computation of the renormalized
expectation value of the stress-energy tensor of a massless, minimally coupled
scalar with a quartic self-interaction on a locally de Sitter background. This
model is important because it demonstrates that quantum effects can lead to
violations of the weak energy condition on cosmological scales - on average,
not just in fluctuations - although the effect in this particular model is far
too small to be observed. The revision consists of modifying the propagator so
that dimensional regularization can be used when the dimension of the
renormalized theory is not four. Although the finite part of the stress-energy
tensor does not change (in D=4) from our previous result, the counterterms do.
We also speculate that a certain, finite and separately conserved part of the
stress tensor can be subsumed into a natural correction of the initial state
from free Bunch-Davies vacuum.
| [
{
"created": "Thu, 24 Jun 2004 11:45:55 GMT",
"version": "v1"
},
{
"created": "Fri, 2 Jul 2004 14:44:06 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Onemli",
"V. K.",
""
],
[
"Woodard",
"R. P.",
""
]
] | We report on a revision of our previous computation of the renormalized expectation value of the stress-energy tensor of a massless, minimally coupled scalar with a quartic self-interaction on a locally de Sitter background. This model is important because it demonstrates that quantum effects can lead to violations of the weak energy condition on cosmological scales - on average, not just in fluctuations - although the effect in this particular model is far too small to be observed. The revision consists of modifying the propagator so that dimensional regularization can be used when the dimension of the renormalized theory is not four. Although the finite part of the stress-energy tensor does not change (in D=4) from our previous result, the counterterms do. We also speculate that a certain, finite and separately conserved part of the stress tensor can be subsumed into a natural correction of the initial state from free Bunch-Davies vacuum. |
1212.5053 | Enrico Barausse | Enrico Barausse, Carlos Palenzuela, Marcelo Ponce and Luis Lehner | Neutron-star mergers in scalar-tensor theories of gravity | 5 pages, 4 figures. One simulation highlighting a new physical effect
has been added (cf. Fig 4) and the text has been modified, to match the
version accepted for publication in PRD Rapid Communications | Phys. Rev. D 87, 081506(R) (2013) | 10.1103/PhysRevD.87.081506 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Scalar-tensor theories of gravity are natural phenomenological alternatives
to General Relativity, where the gravitational interaction is mediated by a
scalar degree of freedom, besides the usual tensor gravitons. In regions of the
parameter space of these theories where constraints from both solar system
experiments and binary-pulsar observations are satisfied, we show that binaries
of neutron stars present marked differences from General Relativity in both the
late-inspiral and merger phases. In particular, phenomena related to the
spontaneous scalarization of isolated neutron stars take place in the late
stages of the evolution of binary systems, with important effects in the
ensuing dynamics. We comment on the relevance of our results for the upcoming
Advanced LIGO/Virgo detectors.
| [
{
"created": "Thu, 20 Dec 2012 14:30:05 GMT",
"version": "v1"
},
{
"created": "Wed, 24 Apr 2013 14:39:42 GMT",
"version": "v2"
}
] | 2013-04-29 | [
[
"Barausse",
"Enrico",
""
],
[
"Palenzuela",
"Carlos",
""
],
[
"Ponce",
"Marcelo",
""
],
[
"Lehner",
"Luis",
""
]
] | Scalar-tensor theories of gravity are natural phenomenological alternatives to General Relativity, where the gravitational interaction is mediated by a scalar degree of freedom, besides the usual tensor gravitons. In regions of the parameter space of these theories where constraints from both solar system experiments and binary-pulsar observations are satisfied, we show that binaries of neutron stars present marked differences from General Relativity in both the late-inspiral and merger phases. In particular, phenomena related to the spontaneous scalarization of isolated neutron stars take place in the late stages of the evolution of binary systems, with important effects in the ensuing dynamics. We comment on the relevance of our results for the upcoming Advanced LIGO/Virgo detectors. |
2212.07463 | Philippe G. LeFloch | Philippe G. LeFloch and Yue Ma | Nonlinear stability of self-gravitating massive fields. A
wave-Klein-Gordon model | 36 pages. arXiv admin note: text overlap with arXiv:1712.10045 | null | 10.1088/1361-6382/acde31 | null | gr-qc math.AP | http://creativecommons.org/licenses/by/4.0/ | Significant advances were made in recent years on the global evolution
problem for self-gravitating massive matter in the small-perturbative regime
close to Minkowski spacetime. To study the coupling between a Klein-Gordon
equation and Einstein's field equations, we introduced the
``Euclidean-hyperboloidal foliation method'', which is based on the
construction of a spacetime foliation adapted to the derivation of sharp decay
estimates for wave and Klein-Gordon equations in a curved spacetime. We give
here an outline of this method, together with a full proof for a
wave-Klein-Gordon model which retains some main challenges arising with the
Einstein-matter system.
| [
{
"created": "Wed, 14 Dec 2022 19:14:43 GMT",
"version": "v1"
}
] | 2023-07-12 | [
[
"LeFloch",
"Philippe G.",
""
],
[
"Ma",
"Yue",
""
]
] | Significant advances were made in recent years on the global evolution problem for self-gravitating massive matter in the small-perturbative regime close to Minkowski spacetime. To study the coupling between a Klein-Gordon equation and Einstein's field equations, we introduced the ``Euclidean-hyperboloidal foliation method'', which is based on the construction of a spacetime foliation adapted to the derivation of sharp decay estimates for wave and Klein-Gordon equations in a curved spacetime. We give here an outline of this method, together with a full proof for a wave-Klein-Gordon model which retains some main challenges arising with the Einstein-matter system. |
1502.04507 | Amin Salehi | Amin Salehi and S. Aftabi | Searching for a Cosmological Preferred Axis in complicated class of
cosmological models:Case study $f(R,T)$ model | 40 page 25 fig. arXiv admin note: text overlap with arXiv:1303.0961,
arXiv:1302.1866, arXiv:1411.1466, arXiv:1107.5807, arXiv:1306.3164 by other
authors | JHEP 1609(2016)140 | 10.1007/JHEP09(2016)140 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recent astronomical observations show that the universe may be anisotropic on
large scales. The Union2 SnIa data hint that the universe has a preferred
direction. If such a cosmological privileged axis indeed exists, one has to
consider an anisotropic expanding Universe instead of the isotropic
cosmological model. In this paper, we present a detailed analysis of the dark
energy dipole in $f(R,T)=f_{1}(R)+f_{2}(T)$ Cosmological Model using three
types of dipole fit (DF) method which are (I)dipole + monopole fitting for
distance modulus(DMFDM), (II)dipole + monopole fitting for luminosity
distance(DMFLD) and (III) general dipole fitting for luminosity
distance(GDFLD). We have found the maximum anisotropic deviation direction for
(DMFDM) method as $(l, b)=(315^{+25}_{-25},-23^{+14}_{-15})$, for (DMFLD) as
$(l, b)=(l, b)=(315^{+35}_{-37},-23^{+18}_{-18})$, and for (GDFLD) method as
$(l, b)=(317^{+32}_{-32},-23^{+18}_{-18})$ which are located very close to each
other. We compare our model with the $CPL$, $\Lambda CDM$ and $\omega CDM$
models. Constraints on $(l, b)$ in $f(R, T)$ model are not much different from
the cases of the $CPL$, $\Lambda CDM$ and $\omega CDM$ models. Moreover, the
results are consistent with other studies.
| [
{
"created": "Mon, 16 Feb 2015 12:17:40 GMT",
"version": "v1"
},
{
"created": "Fri, 20 Feb 2015 05:25:10 GMT",
"version": "v2"
},
{
"created": "Mon, 7 Mar 2016 14:04:23 GMT",
"version": "v3"
},
{
"created": "Sun, 17 Jul 2016 20:49:25 GMT",
"version": "v4"
}
] | 2019-07-03 | [
[
"Salehi",
"Amin",
""
],
[
"Aftabi",
"S.",
""
]
] | Recent astronomical observations show that the universe may be anisotropic on large scales. The Union2 SnIa data hint that the universe has a preferred direction. If such a cosmological privileged axis indeed exists, one has to consider an anisotropic expanding Universe instead of the isotropic cosmological model. In this paper, we present a detailed analysis of the dark energy dipole in $f(R,T)=f_{1}(R)+f_{2}(T)$ Cosmological Model using three types of dipole fit (DF) method which are (I)dipole + monopole fitting for distance modulus(DMFDM), (II)dipole + monopole fitting for luminosity distance(DMFLD) and (III) general dipole fitting for luminosity distance(GDFLD). We have found the maximum anisotropic deviation direction for (DMFDM) method as $(l, b)=(315^{+25}_{-25},-23^{+14}_{-15})$, for (DMFLD) as $(l, b)=(l, b)=(315^{+35}_{-37},-23^{+18}_{-18})$, and for (GDFLD) method as $(l, b)=(317^{+32}_{-32},-23^{+18}_{-18})$ which are located very close to each other. We compare our model with the $CPL$, $\Lambda CDM$ and $\omega CDM$ models. Constraints on $(l, b)$ in $f(R, T)$ model are not much different from the cases of the $CPL$, $\Lambda CDM$ and $\omega CDM$ models. Moreover, the results are consistent with other studies. |
1904.07191 | Grigoris Panotopoulos | Il\'idio Lopes and Grigoris Panotopoulos | Radial oscillations of boson stars made of ultralight repulsive dark
matter | References added | Nucl. Phys. B961 (2020) 115266 | 10.1016/j.nuclphysb.2020.115266 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compute the lowest frequency radial oscillation modes of boson stars. It
is assumed that the object is made of pseudo-Goldstone bosons subjected to a
scalar potential that leads to a repulsive self-interaction force, and which is
characterized by two unknown mass scales $m$ (mass of the particle) and $F$
(decay constant). First we integrate the Tolman-Oppenheimer-Volkoff equations
for the hydrostatic equilibrium of the star, and then we solve the
Sturm-Liouville boundary value problem for the perturbations using the shooting
method. The effective potential that enters into the Schr{\"o}dinger-like
equation as well as several associated eigenfunctions are shown as well.
Moreover, we found that the large frequency separation, i.e. the difference
between consecutive modes, is proportional to the square root of the mass of
the star and the cube of the mass scale defined by $\Lambda \equiv \sqrt{m F}$.
| [
{
"created": "Mon, 15 Apr 2019 17:05:44 GMT",
"version": "v1"
},
{
"created": "Mon, 22 Apr 2019 16:21:15 GMT",
"version": "v2"
}
] | 2020-12-15 | [
[
"Lopes",
"Ilídio",
""
],
[
"Panotopoulos",
"Grigoris",
""
]
] | We compute the lowest frequency radial oscillation modes of boson stars. It is assumed that the object is made of pseudo-Goldstone bosons subjected to a scalar potential that leads to a repulsive self-interaction force, and which is characterized by two unknown mass scales $m$ (mass of the particle) and $F$ (decay constant). First we integrate the Tolman-Oppenheimer-Volkoff equations for the hydrostatic equilibrium of the star, and then we solve the Sturm-Liouville boundary value problem for the perturbations using the shooting method. The effective potential that enters into the Schr{\"o}dinger-like equation as well as several associated eigenfunctions are shown as well. Moreover, we found that the large frequency separation, i.e. the difference between consecutive modes, is proportional to the square root of the mass of the star and the cube of the mass scale defined by $\Lambda \equiv \sqrt{m F}$. |
0712.3188 | Alexander E. Shalyt-Margolin | A. E. Shalyt-Margolin | Vacuum Energy Problem, Fundamental Length and Deformed Quantum Field
Theory | 12 pages | null | null | null | gr-qc | null | The cosmological constant (vacuum energy) problem is analyzed within the
scope of quantum theories with UV-cut-off or fundamental length. Various cases
associated with the appearance of the latter are considered both using the
Generalized Uncertainty Relations and the deformed density matrix,previously
introduced in the author's works. The use of the deformed density matrix is
examined in detail. It is demonstrated that, provided the Fischler-Susskind
cosmic holographic conjecture is valid, the Vacuum Energy Density takes a value
close to the experimental one. The arguments supporting the validity of this
conjecture are given on the basis of the recently obtained results on
Gravitational Holography.
| [
{
"created": "Wed, 19 Dec 2007 13:53:03 GMT",
"version": "v1"
}
] | 2007-12-20 | [
[
"Shalyt-Margolin",
"A. E.",
""
]
] | The cosmological constant (vacuum energy) problem is analyzed within the scope of quantum theories with UV-cut-off or fundamental length. Various cases associated with the appearance of the latter are considered both using the Generalized Uncertainty Relations and the deformed density matrix,previously introduced in the author's works. The use of the deformed density matrix is examined in detail. It is demonstrated that, provided the Fischler-Susskind cosmic holographic conjecture is valid, the Vacuum Energy Density takes a value close to the experimental one. The arguments supporting the validity of this conjecture are given on the basis of the recently obtained results on Gravitational Holography. |
2406.10644 | Ivan Arraut Dr. | Ivan Arraut | The solution to the Black Hole information paradox | 5 pages | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The information paradox suggests that the black hole loses information when
it emits radiation. In this way, the spectrum of radiation corresponds to a
mixed (non-pure) quantum state even if the internal state generating the
black-hole is expected to be pure in essence. In this paper we propose an
argument solving this paradox by understanding the process of spontaneous
symmetry breaking when the black-hole selects one among the many possible
ground states, emitting then radiation as a consequence of it. Here the
particle operator number is the order parameter. This mechanism explains the
connection between the density matrix corresponding to the pure state
describing the black-hole state and the density matrix describing the spectrum
of radiation (mixed quantum state). From this perspective, we can recover the
black-hole information from the superposition principle applied to the
different possible order parameters (particle number operators).
| [
{
"created": "Sat, 15 Jun 2024 14:20:06 GMT",
"version": "v1"
}
] | 2024-06-18 | [
[
"Arraut",
"Ivan",
""
]
] | The information paradox suggests that the black hole loses information when it emits radiation. In this way, the spectrum of radiation corresponds to a mixed (non-pure) quantum state even if the internal state generating the black-hole is expected to be pure in essence. In this paper we propose an argument solving this paradox by understanding the process of spontaneous symmetry breaking when the black-hole selects one among the many possible ground states, emitting then radiation as a consequence of it. Here the particle operator number is the order parameter. This mechanism explains the connection between the density matrix corresponding to the pure state describing the black-hole state and the density matrix describing the spectrum of radiation (mixed quantum state). From this perspective, we can recover the black-hole information from the superposition principle applied to the different possible order parameters (particle number operators). |
2307.12758 | Bayram Tekin | Bayram Tekin | A Tribute to S. Deser: Conserved Quantities in Generic Gravity Theories | 1 figure, 38 pages, includes a brief reminiscence of the author about
S.Deser, a reference added in v2 | null | null | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | I describe parts of my joint work with S. Deser [March 19, 1931 - April 21,
2023] which started when I was working as a post-doc at Brandeis University in
2001. Our work was mostly, but not exclusively, on conserved charges of higher
curvature theories of gravity. I also describe some recent developments, such
as expressing the conserved charges in terms of the linearized Riemann tensor;
I expound upon the computations. I also reminisce about our interaction for
over two decades that went beyond our scientific collaboration. The physics
part of this review is intended for graduate students and researchers
interested in extended theories of gravity, especially about the conserved
quantities and perturbative techniques in these theories.
| [
{
"created": "Mon, 24 Jul 2023 13:03:09 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Aug 2023 10:17:40 GMT",
"version": "v2"
}
] | 2023-08-16 | [
[
"Tekin",
"Bayram",
""
]
] | I describe parts of my joint work with S. Deser [March 19, 1931 - April 21, 2023] which started when I was working as a post-doc at Brandeis University in 2001. Our work was mostly, but not exclusively, on conserved charges of higher curvature theories of gravity. I also describe some recent developments, such as expressing the conserved charges in terms of the linearized Riemann tensor; I expound upon the computations. I also reminisce about our interaction for over two decades that went beyond our scientific collaboration. The physics part of this review is intended for graduate students and researchers interested in extended theories of gravity, especially about the conserved quantities and perturbative techniques in these theories. |
1910.08708 | Swetha Bhagwat | Swetha Bhagwat, Xisco Jimenez Forteza, Paolo Pani, Valeria Ferrari | Ringdown overtones, black hole spectroscopy, and no-hair theorem tests | 19 pages, 18 figures (updated to the version in PRD) | Phys. Rev. D 101, 044033 (2020) | 10.1103/PhysRevD.101.044033 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Validating the black-hole no-hair theorem with gravitational-wave
observations of compact binary coalescences provides a compelling argument that
the remnant object is indeed a black hole as described by the general theory of
relativity. This requires performing a spectroscopic analysis of the
post-merger signal and resolving the frequencies of either different angular
modes or overtones (of the same angular mode). For a nearly-equal mass binary
black-hole system, only the dominant angular mode ($l=m=2$) is sufficiently
excited and the overtones are instrumental to perform this test. Here we
investigate the robustness of modelling the post-merger signal of a binary
black hole coalescence as a superposition of overtones. Further, we study the
bias expected in the recovered frequencies as a function of the start time of a
spectroscopic analysis and provide a computationally cheap procedure to choose
it based on the interplay between the expected statistical error due to the
detector noise and the systematic errors due to waveform modelling. Moreover,
since the overtone frequencies are closely spaced, we find that resolving the
overtones is particularly challenging and requires a loud ringdown signal.
Rayleigh's resolvability criterion suggests that in an optimistic scenario a
ringdown signal-to-noise ratio larger than $\sim 30$ (achievable possibly with
LIGO at design sensitivity and routinely with future interferometers such as
Einstein Telescope, Cosmic Explorer, and LISA) is necessary to resolve the
overtone frequencies. We then conclude by discussing some conceptual issues
associated with black-hole spectroscopy with overtones.
| [
{
"created": "Sat, 19 Oct 2019 06:01:56 GMT",
"version": "v1"
},
{
"created": "Tue, 14 Jan 2020 14:34:54 GMT",
"version": "v2"
}
] | 2020-02-19 | [
[
"Bhagwat",
"Swetha",
""
],
[
"Forteza",
"Xisco Jimenez",
""
],
[
"Pani",
"Paolo",
""
],
[
"Ferrari",
"Valeria",
""
]
] | Validating the black-hole no-hair theorem with gravitational-wave observations of compact binary coalescences provides a compelling argument that the remnant object is indeed a black hole as described by the general theory of relativity. This requires performing a spectroscopic analysis of the post-merger signal and resolving the frequencies of either different angular modes or overtones (of the same angular mode). For a nearly-equal mass binary black-hole system, only the dominant angular mode ($l=m=2$) is sufficiently excited and the overtones are instrumental to perform this test. Here we investigate the robustness of modelling the post-merger signal of a binary black hole coalescence as a superposition of overtones. Further, we study the bias expected in the recovered frequencies as a function of the start time of a spectroscopic analysis and provide a computationally cheap procedure to choose it based on the interplay between the expected statistical error due to the detector noise and the systematic errors due to waveform modelling. Moreover, since the overtone frequencies are closely spaced, we find that resolving the overtones is particularly challenging and requires a loud ringdown signal. Rayleigh's resolvability criterion suggests that in an optimistic scenario a ringdown signal-to-noise ratio larger than $\sim 30$ (achievable possibly with LIGO at design sensitivity and routinely with future interferometers such as Einstein Telescope, Cosmic Explorer, and LISA) is necessary to resolve the overtone frequencies. We then conclude by discussing some conceptual issues associated with black-hole spectroscopy with overtones. |
2201.13146 | Stavros Venikoudis | S.A. Venikoudis (Aristotle U., Thessaloniki), K.V. Fasoulakos
(Aristotle U., Thessaloniki), F.P. Fronimos (Aristotle U., Thessaloniki) | Late-time Cosmology of scalar field assisted $f(\mathcal{G})$ gravity | IJMPD Accepted | null | 10.1142/S0218271822500389 | null | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by/4.0/ | In this work we present the late-time behaviour of the Universe in the
context of Einstein-Gauss-Bonnet gravitational theory. The theory involves a
scalar field, which represents low-effective quantum corrections, assisted by a
function $f(\mathcal{G})$ solely depending from the Gauss-Bonnet topological
invariant $\mathcal{G}$. It is considered that the dark energy serves as the
impact of all geometric terms, which are included in the gravitational action
and the density of dark energy acts as a time dependent cosmological constant
evolving with an infinitesimal rate and driving the Universe into an
accelerating expansion. We examine two cosmological models of interest. The
first involves a canonical scalar field in the presence of a scalar potential
while the second, involves a scalar field which belongs to a generalized class
of theories $f(\phi,X)$ namely the k-essence scalar field in the absence of
scalar potential. As it is proved, the aforementioned models are in consistency
with the latest Planck data and in relatively good agreement with the
$\Lambda$CDM standard cosmological model. The absence of dark energy
oscillations at the early stages of matter dominated era, which appear in
alternative scenarios of cosmological dynamics in the context of modified
$f(R)$ gravitational theories, indicates an advantage of the theory for the
interpretation of late-time phenomenology.
| [
{
"created": "Mon, 31 Jan 2022 11:45:23 GMT",
"version": "v1"
}
] | 2022-04-19 | [
[
"Venikoudis",
"S. A.",
"",
"Aristotle U., Thessaloniki"
],
[
"Fasoulakos",
"K. V.",
"",
"Aristotle U., Thessaloniki"
],
[
"Fronimos",
"F. P.",
"",
"Aristotle U., Thessaloniki"
]
] | In this work we present the late-time behaviour of the Universe in the context of Einstein-Gauss-Bonnet gravitational theory. The theory involves a scalar field, which represents low-effective quantum corrections, assisted by a function $f(\mathcal{G})$ solely depending from the Gauss-Bonnet topological invariant $\mathcal{G}$. It is considered that the dark energy serves as the impact of all geometric terms, which are included in the gravitational action and the density of dark energy acts as a time dependent cosmological constant evolving with an infinitesimal rate and driving the Universe into an accelerating expansion. We examine two cosmological models of interest. The first involves a canonical scalar field in the presence of a scalar potential while the second, involves a scalar field which belongs to a generalized class of theories $f(\phi,X)$ namely the k-essence scalar field in the absence of scalar potential. As it is proved, the aforementioned models are in consistency with the latest Planck data and in relatively good agreement with the $\Lambda$CDM standard cosmological model. The absence of dark energy oscillations at the early stages of matter dominated era, which appear in alternative scenarios of cosmological dynamics in the context of modified $f(R)$ gravitational theories, indicates an advantage of the theory for the interpretation of late-time phenomenology. |
2305.02196 | Benrong Mu | Yiqian He, Benrong Mu | Thermodynamic instabilities of Kerr-Newman Ads black holes | 10 pages, 2 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In~\cite{Johnson:2019mdp}, Clifford put forward that the specific heat at
constant volume $C_{V}$ is always negetive for the super-entropy black hole.
Later in~\cite{Cong:2019bud}, Robert et al. found $C_{V}>0$ in certain region
for the generalized exotic BTZ black holes. Futhermore, they proposed a new
conjecture that as the $C_{V}>0$, the specific heat at constant pressure
$C_{P}$ always satisfies $C_{P}<0$ in super-entropy black hole. In this paper,
we examine the both conjectures with regard to the thermodynamic instability of
super-entropy black hole. By means of a super-entropy black hole, the
Kerr-Newman-AdS black hole in a coordinate system that rotates at infinity, we
detailedly analyze its character and notice there exists the region where
$C_{V}>0$ and meanwhile $C_{P}>0$. Hence, we find a counterexample to the two
conjectures.
| [
{
"created": "Tue, 2 May 2023 14:48:53 GMT",
"version": "v1"
}
] | 2023-05-04 | [
[
"He",
"Yiqian",
""
],
[
"Mu",
"Benrong",
""
]
] | In~\cite{Johnson:2019mdp}, Clifford put forward that the specific heat at constant volume $C_{V}$ is always negetive for the super-entropy black hole. Later in~\cite{Cong:2019bud}, Robert et al. found $C_{V}>0$ in certain region for the generalized exotic BTZ black holes. Futhermore, they proposed a new conjecture that as the $C_{V}>0$, the specific heat at constant pressure $C_{P}$ always satisfies $C_{P}<0$ in super-entropy black hole. In this paper, we examine the both conjectures with regard to the thermodynamic instability of super-entropy black hole. By means of a super-entropy black hole, the Kerr-Newman-AdS black hole in a coordinate system that rotates at infinity, we detailedly analyze its character and notice there exists the region where $C_{V}>0$ and meanwhile $C_{P}>0$. Hence, we find a counterexample to the two conjectures. |
2302.14183 | Zhaoyi Xu | Zhaoyi Xu | Semi-classical rotating black hole in loop quantum gravity | 5 pages | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the research paper [1], the analytical solution of semi-classical rotating
black holes (BH) in loop quantum gravity theory (LQG) is obtained, but an
unknown function $H$ is still preserved. In this note, we obtain an expression
for the unknown function $H$, which makes the space-time line element of the
semi-classical rotating BH in the LQG theory sufficiently well-expressed and
thus provides a basis for the study of such rotating BHs.
| [
{
"created": "Mon, 27 Feb 2023 22:47:58 GMT",
"version": "v1"
}
] | 2023-03-01 | [
[
"Xu",
"Zhaoyi",
""
]
] | In the research paper [1], the analytical solution of semi-classical rotating black holes (BH) in loop quantum gravity theory (LQG) is obtained, but an unknown function $H$ is still preserved. In this note, we obtain an expression for the unknown function $H$, which makes the space-time line element of the semi-classical rotating BH in the LQG theory sufficiently well-expressed and thus provides a basis for the study of such rotating BHs. |
2211.05956 | Rui-Yun Guo | Tian-Ying Yao, Rui-Yun Guo, Xin-Yue Zhao | Constraining neutrino mass in dynamical dark energy cosmologies with the
logarithm parametrization and the oscillating parametrization | 11 pages,4 figures | Journal of High Energy Physics, Gravitation and Cosmology, 2023 | 10.4236/jhepgc.2023.94076 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We constrain two dynamical dark energy models that are parametrized by the
logarithm form of $w(z)=w_{0}+w_{1}\left(\frac{\ln (2+z)}{1+z}-\ln 2\right)$
and the oscillating form of
$w(z)=w_{0}+w_{1}\left(\frac{\sin(1+z)}{1+z}-\sin(1)\right)$. Comparing with
the Chevallier-Polarski-Linder (CPL) model, the two parametrizations for dark
energy can explore the whole evolution history of the universe properly. Using
the current mainstream observational data including the cosmic microwave
background data and the baryon acoustic oscillation data as well as the type Ia
supernovae data, we perform the $\chi^2$ statistic analysis to global fit these
models, finding that the logarithm parametrization and the oscillating
parametrization are almost as well as the CPL scenario in fitting these data.
We make a comparison for the impacts of the dynamical dark energy on the
cosmological constraints on the total mass of active neutrinos. We find that
the dark energy properties could significantly change the fitting results of
neutrino mass. Looser constraints on $\sum m_{\nu}$ are obtained in the
logarithm and oscillating models than those derived in the CPL model.
Consideration of the possible mass ordering of neutrinos reveals that the most
stringent constraint on $\sum m_{\nu}$ appears in the degenerate hierarchy
case.
| [
{
"created": "Fri, 11 Nov 2022 02:07:19 GMT",
"version": "v1"
},
{
"created": "Thu, 30 Mar 2023 04:39:29 GMT",
"version": "v2"
},
{
"created": "Fri, 22 Sep 2023 07:20:41 GMT",
"version": "v3"
},
{
"created": "Mon, 27 Nov 2023 07:07:33 GMT",
"version": "v4"
}
] | 2023-11-28 | [
[
"Yao",
"Tian-Ying",
""
],
[
"Guo",
"Rui-Yun",
""
],
[
"Zhao",
"Xin-Yue",
""
]
] | We constrain two dynamical dark energy models that are parametrized by the logarithm form of $w(z)=w_{0}+w_{1}\left(\frac{\ln (2+z)}{1+z}-\ln 2\right)$ and the oscillating form of $w(z)=w_{0}+w_{1}\left(\frac{\sin(1+z)}{1+z}-\sin(1)\right)$. Comparing with the Chevallier-Polarski-Linder (CPL) model, the two parametrizations for dark energy can explore the whole evolution history of the universe properly. Using the current mainstream observational data including the cosmic microwave background data and the baryon acoustic oscillation data as well as the type Ia supernovae data, we perform the $\chi^2$ statistic analysis to global fit these models, finding that the logarithm parametrization and the oscillating parametrization are almost as well as the CPL scenario in fitting these data. We make a comparison for the impacts of the dynamical dark energy on the cosmological constraints on the total mass of active neutrinos. We find that the dark energy properties could significantly change the fitting results of neutrino mass. Looser constraints on $\sum m_{\nu}$ are obtained in the logarithm and oscillating models than those derived in the CPL model. Consideration of the possible mass ordering of neutrinos reveals that the most stringent constraint on $\sum m_{\nu}$ appears in the degenerate hierarchy case. |
1901.04307 | L\'eo Bernus | L. Bernus, O. Minazzoli, A. Fienga, M. Gastineau, J. Laskar, P. Deram | Constraining the mass of the graviton with the planetary ephemeris INPOP | New version. Technical details moved into Supplemental Materials.
Author Pierre Deram added. Interpretation in terms of fifth force added.
Minor corrections. 8 pages. 4 figures. 2 tables | Phys. Rev. Lett. 123, 161103 (2019) | 10.1103/PhysRevLett.123.161103 | null | gr-qc astro-ph.EP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We use the planetary ephemeris INPOP17b to constrain the mass of the graviton
in the Newtonian limit. We also give an interpretation of this result for a
specific case of fifth force framework. We find that the residuals for the
Cassini spacecraft significantly (90\% C.L.) degrade for Compton wavelengths of
the graviton smaller than $1.83\times 10^{13}$ km, corresponding to a graviton
mass bigger than $6.76\times 10^{-23} eV/c^2$. This limit is comparable in
magnitude to the one obtained by the LIGO-Virgo collaboration in the radiative
regime. We also use this specific example to illustrate why constraints on
alternative theories of gravity obtained from postfit residuals are generically
overestimated.
| [
{
"created": "Wed, 9 Jan 2019 15:22:19 GMT",
"version": "v1"
},
{
"created": "Thu, 1 Aug 2019 11:51:59 GMT",
"version": "v2"
}
] | 2019-10-23 | [
[
"Bernus",
"L.",
""
],
[
"Minazzoli",
"O.",
""
],
[
"Fienga",
"A.",
""
],
[
"Gastineau",
"M.",
""
],
[
"Laskar",
"J.",
""
],
[
"Deram",
"P.",
""
]
] | We use the planetary ephemeris INPOP17b to constrain the mass of the graviton in the Newtonian limit. We also give an interpretation of this result for a specific case of fifth force framework. We find that the residuals for the Cassini spacecraft significantly (90\% C.L.) degrade for Compton wavelengths of the graviton smaller than $1.83\times 10^{13}$ km, corresponding to a graviton mass bigger than $6.76\times 10^{-23} eV/c^2$. This limit is comparable in magnitude to the one obtained by the LIGO-Virgo collaboration in the radiative regime. We also use this specific example to illustrate why constraints on alternative theories of gravity obtained from postfit residuals are generically overestimated. |
0807.2186 | S. Mignemi | S. Mignemi | Triply special relativity from six dimensions | 7 pages, plain TeX | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that the generalization of Doubly Special Relativity to a curved de
Sitter background can be obtained starting from a six-dimensional spacetime on
which quadratic constraints on position and momentum coordinates are imposed.
| [
{
"created": "Mon, 14 Jul 2008 15:50:06 GMT",
"version": "v1"
}
] | 2008-07-15 | [
[
"Mignemi",
"S.",
""
]
] | We show that the generalization of Doubly Special Relativity to a curved de Sitter background can be obtained starting from a six-dimensional spacetime on which quadratic constraints on position and momentum coordinates are imposed. |
0906.4380 | Alexis Larranaga | Andres Castillo, Alexis Larranaga | Entropy for Black Holes in the Deformed Horava-Lifshitz Gravity | 7 pages, 4 figures | Electron.J.Theor.Phys.8:1-10,2011 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the entropy of black holes in the deformed Horava-Lifshitz gravity
with coupling constant lambda. For lambda=1, the black hole resembles the
Reissner-Norstrom black hole with a geometric parameter acting like the
electric charge. Therefore, we obtain some differences in the entropy when
comparing with the Schwarzschild black hole. Finally, we study the heat
capacity and the thermodynamical stability of this solution.
| [
{
"created": "Wed, 24 Jun 2009 00:03:01 GMT",
"version": "v1"
},
{
"created": "Fri, 26 Jun 2009 14:18:18 GMT",
"version": "v2"
}
] | 2011-05-05 | [
[
"Castillo",
"Andres",
""
],
[
"Larranaga",
"Alexis",
""
]
] | We study the entropy of black holes in the deformed Horava-Lifshitz gravity with coupling constant lambda. For lambda=1, the black hole resembles the Reissner-Norstrom black hole with a geometric parameter acting like the electric charge. Therefore, we obtain some differences in the entropy when comparing with the Schwarzschild black hole. Finally, we study the heat capacity and the thermodynamical stability of this solution. |
1111.0924 | Joel Saavedra | Norman Cruz, Marco Olivares, Joel Saavedra and J.R. Villanueva | Null geodesics in the Reissner-Nordstr\"om Anti-de Sitter black holes | 13 pages, 10 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we address the study of null geodesics in the background of
Reissner-Nordstr\"om Anti de Sitter black holes. We compute the exact
trajectories in terms of elliptic functions of Weierstrass, obtaining a
detailed description of the orbits in terms of charge, mass and the
cosmological constant. The trajectories of the photon are classified using the
impact parameter.
| [
{
"created": "Thu, 3 Nov 2011 17:34:24 GMT",
"version": "v1"
}
] | 2011-11-04 | [
[
"Cruz",
"Norman",
""
],
[
"Olivares",
"Marco",
""
],
[
"Saavedra",
"Joel",
""
],
[
"Villanueva",
"J. R.",
""
]
] | In this work we address the study of null geodesics in the background of Reissner-Nordstr\"om Anti de Sitter black holes. We compute the exact trajectories in terms of elliptic functions of Weierstrass, obtaining a detailed description of the orbits in terms of charge, mass and the cosmological constant. The trajectories of the photon are classified using the impact parameter. |
2110.09503 | Michael Toomey | Stephon Alexander, Steven J. Clark, Gabriel Herczeg, and Michael W.
Toomey | Black hole and cosmological analysis of BF sequestered gravity | 11 pages, 3 figures | null | 10.1103/PhysRevD.105.044001 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study a minimal extension of a recently proposed modification of general
relativity that draws on concepts from topological field theory to resolve
aspects of the cosmological constant problem. In the original model, the field
content of general relativity was augmented to include a gauge field and an
adjoint-valued two-form without modifying the classical gravitational dynamics.
Here we include a kinetic term for the gauge field which sources fluctuations
of the cosmological constant. We then study spherically symmetric black holes
and a simple homogeneous, isotropic cosmological model predicted by the
extended theory. For the black hole case, we observe deviations near the event
horizon as well as a ``charge"-like behavior induced by the gauge field. In the
cosmological case, $\dot{H}$ is always positive and some solutions asymptote to
a constant $H$.
| [
{
"created": "Mon, 18 Oct 2021 17:51:15 GMT",
"version": "v1"
}
] | 2022-02-16 | [
[
"Alexander",
"Stephon",
""
],
[
"Clark",
"Steven J.",
""
],
[
"Herczeg",
"Gabriel",
""
],
[
"Toomey",
"Michael W.",
""
]
] | We study a minimal extension of a recently proposed modification of general relativity that draws on concepts from topological field theory to resolve aspects of the cosmological constant problem. In the original model, the field content of general relativity was augmented to include a gauge field and an adjoint-valued two-form without modifying the classical gravitational dynamics. Here we include a kinetic term for the gauge field which sources fluctuations of the cosmological constant. We then study spherically symmetric black holes and a simple homogeneous, isotropic cosmological model predicted by the extended theory. For the black hole case, we observe deviations near the event horizon as well as a ``charge"-like behavior induced by the gauge field. In the cosmological case, $\dot{H}$ is always positive and some solutions asymptote to a constant $H$. |
2107.11193 | Grigory Volovik | G.E. Volovik | Effect of the inner horizon on the black hole thermodynamics:
Reissner-Nordstr\"om black hole and Kerr black hole | 7 pages, no figures, accepted in Mod. Phys. Lett. A | null | null | null | gr-qc cond-mat.other hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | For the Schwarzschild black hole the Bekenstein-Hawking entropy is
proportional to the area of the event horizon. For the black holes with two
horizons the thermodynamics is not very clear, since the role of the inner
horizons is not well established. Here we calculate the entropy of the
Reissner-Nordstr\"om black hole and of the Kerr black hole, which have two
horizons. For the spherically symmetric Reissner-Nordstr\"om black hole we used
several different approaches. All of them give the same result for the entropy
and for the corresponding temperature of the thermal Hawking radiation. The
entropy is not determined by the area of the outer horizon, and it is not equal
to the sum of the entropies of two horizons. It is determined by the
correlations between the two horizons, due to which the total entropy of the
black hole and the temperature of Hawking radiation depend only on mass $M$ of
the black hole and do not depend on the black hole charge $Q$. For the Kerr and
Kerr-Newman black holes it is shown that their entropy has the similar
property: it depends only on mass $M$ of the black hole and does not depend on
the angular momentum $J$ and charge $Q$.
| [
{
"created": "Wed, 21 Jul 2021 08:07:41 GMT",
"version": "v1"
}
] | 2021-07-26 | [
[
"Volovik",
"G. E.",
""
]
] | For the Schwarzschild black hole the Bekenstein-Hawking entropy is proportional to the area of the event horizon. For the black holes with two horizons the thermodynamics is not very clear, since the role of the inner horizons is not well established. Here we calculate the entropy of the Reissner-Nordstr\"om black hole and of the Kerr black hole, which have two horizons. For the spherically symmetric Reissner-Nordstr\"om black hole we used several different approaches. All of them give the same result for the entropy and for the corresponding temperature of the thermal Hawking radiation. The entropy is not determined by the area of the outer horizon, and it is not equal to the sum of the entropies of two horizons. It is determined by the correlations between the two horizons, due to which the total entropy of the black hole and the temperature of Hawking radiation depend only on mass $M$ of the black hole and do not depend on the black hole charge $Q$. For the Kerr and Kerr-Newman black holes it is shown that their entropy has the similar property: it depends only on mass $M$ of the black hole and does not depend on the angular momentum $J$ and charge $Q$. |
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