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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
2309.01595 | Leihua Liu | Tao Li, Lei-Hua Liu | Cosmological complexity of the modified dispersion relation | matching the published version | Phys.Lett.B 854 (2024) 138728 | 10.1016/j.physletb.2024.138728 | null | gr-qc astro-ph.CO hep-ph hep-th quant-ph | http://creativecommons.org/licenses/by/4.0/ | Complexity will be more and more essential in high-energy physics. It is
naturally extended into the very early universe. Considering the universe as a
quantum chaotic system, the curvature perturbation of the scalar field is
identified with the two-mode squeezed state. By solving the
Schr$\ddot{o}$dinger equation, one can obtain the numerical solutions of the
angle parameter and squeezing parameter. The solution of the squeezing
parameter mainly determines the evolution of complexity. Our numeric indicates
that the complexity of the modified dispersion relation will have a non-linear
pattern after the horizon exits. Meanwhile, its corresponding Lyapunov index is
also larger compared with the standard case. During the inflationary period,
the complexity will irregularly oscillate and its scrambling time is also
shorter compared with the standard case. Since the modified dispersion relation
can be dubbed as the consequences of various frameworks of quantum gravity, it
could be applicable to these frameworks. Finally, one can expect the framework
of quantum gravity will lead to the fruitful evolution of complexity, which
guides us in distinguishing various inflationary models.
| [
{
"created": "Mon, 4 Sep 2023 13:26:20 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Sep 2023 13:44:52 GMT",
"version": "v2"
},
{
"created": "Thu, 23 May 2024 07:51:09 GMT",
"version": "v3"
}
] | 2024-05-24 | [
[
"Li",
"Tao",
""
],
[
"Liu",
"Lei-Hua",
""
]
] | Complexity will be more and more essential in high-energy physics. It is naturally extended into the very early universe. Considering the universe as a quantum chaotic system, the curvature perturbation of the scalar field is identified with the two-mode squeezed state. By solving the Schr$\ddot{o}$dinger equation, one can obtain the numerical solutions of the angle parameter and squeezing parameter. The solution of the squeezing parameter mainly determines the evolution of complexity. Our numeric indicates that the complexity of the modified dispersion relation will have a non-linear pattern after the horizon exits. Meanwhile, its corresponding Lyapunov index is also larger compared with the standard case. During the inflationary period, the complexity will irregularly oscillate and its scrambling time is also shorter compared with the standard case. Since the modified dispersion relation can be dubbed as the consequences of various frameworks of quantum gravity, it could be applicable to these frameworks. Finally, one can expect the framework of quantum gravity will lead to the fruitful evolution of complexity, which guides us in distinguishing various inflationary models. |
1210.4541 | Andrew J. S. Hamilton | Andrew J. S. Hamilton | Illusory horizons, thermodynamics, and holography inside black holes | 13 pages, 7 figures. To appear in the Proceedings of the conference
"Relativity and Gravitation, 100 Years after Einstein in Prague", Prague,
Czech Republic, June 25-29, 2012 | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | There is persistent and endemic confusion between the true (future) horizon
and the illusory (past) horizon of a black hole. The illusory horizon is the
redshifting surface of matter that fell into the black hole long ago. A person
who free-falls through the horizon of a black hole falls through the true
horizon, not the illusory horizon. The infaller continues to see the illusory
horizon ahead of them, all the way down to the classical singularity. The
illusory horizon is the source of Hawking radiation, for both outsiders and
infallers. The entropy of a black hole is 1/4 of the area of the illusory
horizon, for both outsiders and infallers. The illusory horizon holographically
encodes states hidden behind it, for both outsiders and infallers. The endpoint
of an infaller approaching the classical singularity is to merge their states
with the illusory horizon. The holographic boundary of the black hole is then
the union of the illusory horizon and the classical spacelike singularity. When
an infaller reaches the classical singularity, any entanglement of the infaller
with outsiders or other infallers is transferred to entanglement with the
states of the black hole, encoded on the illusory horizon. Locality holds
between an infaller and a spacelike-separated outsider or other infaller as
long as their future lightcones intersect before the singularity, but breaks
down when the future lightcones no longer intersect.
| [
{
"created": "Tue, 16 Oct 2012 19:55:27 GMT",
"version": "v1"
}
] | 2012-10-17 | [
[
"Hamilton",
"Andrew J. S.",
""
]
] | There is persistent and endemic confusion between the true (future) horizon and the illusory (past) horizon of a black hole. The illusory horizon is the redshifting surface of matter that fell into the black hole long ago. A person who free-falls through the horizon of a black hole falls through the true horizon, not the illusory horizon. The infaller continues to see the illusory horizon ahead of them, all the way down to the classical singularity. The illusory horizon is the source of Hawking radiation, for both outsiders and infallers. The entropy of a black hole is 1/4 of the area of the illusory horizon, for both outsiders and infallers. The illusory horizon holographically encodes states hidden behind it, for both outsiders and infallers. The endpoint of an infaller approaching the classical singularity is to merge their states with the illusory horizon. The holographic boundary of the black hole is then the union of the illusory horizon and the classical spacelike singularity. When an infaller reaches the classical singularity, any entanglement of the infaller with outsiders or other infallers is transferred to entanglement with the states of the black hole, encoded on the illusory horizon. Locality holds between an infaller and a spacelike-separated outsider or other infaller as long as their future lightcones intersect before the singularity, but breaks down when the future lightcones no longer intersect. |
0908.4102 | David Garfinkle | David Garfinkle | The motion of galaxy clusters in inhomogeneous cosmologies | 7 pages, 2 figures | Class.Quant.Grav.27:065002,2010 | 10.1088/0264-9381/27/6/065002 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Lemaitre-Tolman-Bondi inhomogeneous spacetimes can be used as a cosmological
model to account for the type Ia supernova data. However, such models also give
rise to large velocities of galaxy clusters with respect to the cosmic
microwave background. Those velocities can be measured using the kinematic
Sunyaev-Zeldovich effect. This paper presents a calculation of galaxy cluster
velocities as a function of redshift for such a model.
| [
{
"created": "Thu, 27 Aug 2009 21:32:11 GMT",
"version": "v1"
}
] | 2010-02-23 | [
[
"Garfinkle",
"David",
""
]
] | Lemaitre-Tolman-Bondi inhomogeneous spacetimes can be used as a cosmological model to account for the type Ia supernova data. However, such models also give rise to large velocities of galaxy clusters with respect to the cosmic microwave background. Those velocities can be measured using the kinematic Sunyaev-Zeldovich effect. This paper presents a calculation of galaxy cluster velocities as a function of redshift for such a model. |
2012.00027 | Rossella Gamba | Rossella Gamba, Sebastiano Bernuzzi, Alessandro Nagar | Fast, faithful, frequency-domain effective-one-body waveforms for
compact binary coalescences | null | null | 10.1103/PhysRevD.104.084058 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The inference of binary neutron star properties from gravitational-wave
observations requires the generation of millions of waveforms, each one
spanning about three order of magnitudes in frequency range. Thus, waveform
models must be efficiently generated and, at the same time, be faithful from
the post-Newtonian quasi-adiabatic inspiral up to the merger regime. A simple
solution to this problem is to combine effective-one-body waveforms with the
stationary phase approximation to obtain frequency-domain multipolar
approximants valid from any low frequency to merger. We demonstrate that
effective-one-body frequency-domain waveforms generated in post-adiabatic
approximation are computationally competitive with current phenomenological and
surrogate models, (virtually) arbitrarily long, and faithful up to merger for
any binary parameter. The same method can also be used to efficiently generate
intermediate mass binary black hole inspiral waveforms detectable by
space-based interferometers.
| [
{
"created": "Mon, 30 Nov 2020 19:00:06 GMT",
"version": "v1"
}
] | 2021-10-27 | [
[
"Gamba",
"Rossella",
""
],
[
"Bernuzzi",
"Sebastiano",
""
],
[
"Nagar",
"Alessandro",
""
]
] | The inference of binary neutron star properties from gravitational-wave observations requires the generation of millions of waveforms, each one spanning about three order of magnitudes in frequency range. Thus, waveform models must be efficiently generated and, at the same time, be faithful from the post-Newtonian quasi-adiabatic inspiral up to the merger regime. A simple solution to this problem is to combine effective-one-body waveforms with the stationary phase approximation to obtain frequency-domain multipolar approximants valid from any low frequency to merger. We demonstrate that effective-one-body frequency-domain waveforms generated in post-adiabatic approximation are computationally competitive with current phenomenological and surrogate models, (virtually) arbitrarily long, and faithful up to merger for any binary parameter. The same method can also be used to efficiently generate intermediate mass binary black hole inspiral waveforms detectable by space-based interferometers. |
2105.02161 | JiaMao Lin | Jia-Mao Lin, Ming-Jian Luo, Zi-Han Zheng, Lei Yin, Jia-Hui Huang | Extremal rotating black holes, scalar perturbation and superradiant
stability | 7 pages,4 figures,references added | null | 10.1016/j.physletb.2021.136392 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A (charged) rotating black hole may be unstable against a (charged) massive
scalar field perturbation due to the existence of superradiance modes. The
stability property depends on the parameters of the system. In this paper, the
superradiant stable parameter space is studied for the four-dimensional
extremal Kerr and Kerr-Newman black holes under massive and charged massive
scalar perturbation. For the extremal Kerr case, it is found that when the
angular frequency and proper mass of the scalar perturbation satisfy the
inequality $\omega<\mu/\sqrt{3}$, the extremal Kerr black hole and scalar
perturbation system is superradiantly stable. For the Kerr-Newman black hole
case, when the angular frequency of the scalar perturbation satisfies
$\omega<qQ/M$ and the product of the mass-to-charge ratios of the black hole
and scalar perturbation satisfies $\frac{\mu}{q}\frac{M}{Q} > \frac{\sqrt{3
k^2+2} }{ \sqrt{k^2+2} },~k=\frac{a}{M}$, the extremal Kerr-Newman black hole
is superradiantly stable under charged massive scalar perturbation.
| [
{
"created": "Wed, 5 May 2021 16:16:29 GMT",
"version": "v1"
}
] | 2021-06-02 | [
[
"Lin",
"Jia-Mao",
""
],
[
"Luo",
"Ming-Jian",
""
],
[
"Zheng",
"Zi-Han",
""
],
[
"Yin",
"Lei",
""
],
[
"Huang",
"Jia-Hui",
""
]
] | A (charged) rotating black hole may be unstable against a (charged) massive scalar field perturbation due to the existence of superradiance modes. The stability property depends on the parameters of the system. In this paper, the superradiant stable parameter space is studied for the four-dimensional extremal Kerr and Kerr-Newman black holes under massive and charged massive scalar perturbation. For the extremal Kerr case, it is found that when the angular frequency and proper mass of the scalar perturbation satisfy the inequality $\omega<\mu/\sqrt{3}$, the extremal Kerr black hole and scalar perturbation system is superradiantly stable. For the Kerr-Newman black hole case, when the angular frequency of the scalar perturbation satisfies $\omega<qQ/M$ and the product of the mass-to-charge ratios of the black hole and scalar perturbation satisfies $\frac{\mu}{q}\frac{M}{Q} > \frac{\sqrt{3 k^2+2} }{ \sqrt{k^2+2} },~k=\frac{a}{M}$, the extremal Kerr-Newman black hole is superradiantly stable under charged massive scalar perturbation. |
1204.1699 | XiaoXiong Zeng | Xiao-Xiong Zeng, Wen-Biao Liu | Spectroscopy of a Reissner-Nordstr\"{o}m black hole via an action
variable | 6 pages, 0 figures | Eur. Phys. J. C (2012) 72:1987 | 10.1140/epjc/s10052-012-1987-0 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | With the help of the Bohr--Sommerfeld quantization rule, the area spectrum of
a charged, spherically symmetric spacetime is obtained by studying an adiabatic
invariant action variable. The period of the Einstein-Maxwell system, which is
related to the surface gravity of a given spacetime, is determined by the
Kruskal--like coordinates.
It is shown that the area spectrum of the Reissner-Nordstr\"{o}m black hole
is evenly spaced and the spacing is the same as that of a Schwarzschild black
hole, which indicates that the area spectrum of a black hole is independent of
its parameters. In contrast to the quasi-normal mode analysis, we do not impose
the small charge limit as the general area gap $8\pi $ is obtained.
| [
{
"created": "Sun, 8 Apr 2012 02:27:26 GMT",
"version": "v1"
},
{
"created": "Fri, 20 Apr 2012 09:09:44 GMT",
"version": "v2"
}
] | 2012-04-23 | [
[
"Zeng",
"Xiao-Xiong",
""
],
[
"Liu",
"Wen-Biao",
""
]
] | With the help of the Bohr--Sommerfeld quantization rule, the area spectrum of a charged, spherically symmetric spacetime is obtained by studying an adiabatic invariant action variable. The period of the Einstein-Maxwell system, which is related to the surface gravity of a given spacetime, is determined by the Kruskal--like coordinates. It is shown that the area spectrum of the Reissner-Nordstr\"{o}m black hole is evenly spaced and the spacing is the same as that of a Schwarzschild black hole, which indicates that the area spectrum of a black hole is independent of its parameters. In contrast to the quasi-normal mode analysis, we do not impose the small charge limit as the general area gap $8\pi $ is obtained. |
1905.00356 | Theo Torres | Theo Torres, Sam Patrick, Maur\'icio Richartz and Silke Weinfurtner | Analogue Black Hole Spectroscopy; or, how to listen to dumb holes | 17 pages, 4 figures | Class. Quantum Grav. 36 194002 (2019) | 10.1088/1361-6382/ab3d48 | null | gr-qc physics.flu-dyn | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Spectroscopy is a fundamental tool in science which consists in studying the
response of a system as a function of frequency. Among its many applications in
Physics, Biology, Chemistry and other fields, the possibility of identifying
objects and structures through their emission spectra is remarkable and
incredibly useful. In this paper we apply the spectroscopy idea to a
numerically simulated hydrodynamical flow, with the goal of developing a new,
non-invasive flow measurement technique. Our focus lies on an irrotational
draining vortex, which can be seen, under specific conditions, as the analogue
of a rotating black hole (historically named a dumb hole). This paper is a
development of a recent experiment that suggests that irrotational vortices and
rotating black holes share a common relaxation process, known as the ringdown
phase. We apply techniques borrowed from black hole physics to identify vortex
flows from their characteristic spectrum emitted during this ringdown phase. We
believe that this technique is a new facet of the fluid-gravity analogy and
constitutes a promising way to investigate experimentally vortex flows in
fluids and superfluids alike.
| [
{
"created": "Wed, 1 May 2019 16:11:16 GMT",
"version": "v1"
}
] | 2019-10-07 | [
[
"Torres",
"Theo",
""
],
[
"Patrick",
"Sam",
""
],
[
"Richartz",
"Maurício",
""
],
[
"Weinfurtner",
"Silke",
""
]
] | Spectroscopy is a fundamental tool in science which consists in studying the response of a system as a function of frequency. Among its many applications in Physics, Biology, Chemistry and other fields, the possibility of identifying objects and structures through their emission spectra is remarkable and incredibly useful. In this paper we apply the spectroscopy idea to a numerically simulated hydrodynamical flow, with the goal of developing a new, non-invasive flow measurement technique. Our focus lies on an irrotational draining vortex, which can be seen, under specific conditions, as the analogue of a rotating black hole (historically named a dumb hole). This paper is a development of a recent experiment that suggests that irrotational vortices and rotating black holes share a common relaxation process, known as the ringdown phase. We apply techniques borrowed from black hole physics to identify vortex flows from their characteristic spectrum emitted during this ringdown phase. We believe that this technique is a new facet of the fluid-gravity analogy and constitutes a promising way to investigate experimentally vortex flows in fluids and superfluids alike. |
1805.04327 | Jie-Xiong Mo | Jie-Xiong Mo and Gu-Qiang Li | Effects of Lovelock gravity on the Joule-Thomson expansion | 14pages,5figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Effects of Lovelock gravity on the Joule-Thomson expansion are probed from
various perspectives. The well-known Joule-Thomson coefficient is derived with
both the explicit expression and intuitive image presented. Moreover, the
inversion curves showing the relation between the inversion temperature and the
inversion pressure are studied. It is shown that for given inversion pressure,
the inversion temperature of the case $\alpha\neq0$ ($\alpha$ is the Lovelock
parameter) is much lower than that of the case $\alpha=0$. And the inversion
temperature tends to decrease with $\alpha$, in contrast to the effect of the
electric charge. It is also shown that the ratio between the minimum inversion
temperature and the critical temperature decreases with $\alpha$ for
$\alpha\neq0$. Furthermore, the isenthalpic curves are investigated with rich
physics revealed. The intersection point between the isenthalpic curve and the
inversion curve is exactly the inversion point discriminating the heating
process from cooling process. It is shown that both the inversion temperature
and the inversion pressure for $\alpha\neq0$ are much lower for the same given
mass of the black hole, showing the effect of Lovelock gravity. Last but not
the least, we discuss the case of uncharged Lovelock AdS black holes with
interesting feature found. It is shown that the Joule-Thomson coefficient is
always positive, suggesting the expansion is always in the regime of cooling
process. And no inversion temperature exists, in contrast to the case $Q\neq0$.
Isenthalpic curves are also quite different since the temperature increases
monotonically with the pressure when the mass is specified.
| [
{
"created": "Fri, 11 May 2018 11:24:46 GMT",
"version": "v1"
}
] | 2018-05-14 | [
[
"Mo",
"Jie-Xiong",
""
],
[
"Li",
"Gu-Qiang",
""
]
] | Effects of Lovelock gravity on the Joule-Thomson expansion are probed from various perspectives. The well-known Joule-Thomson coefficient is derived with both the explicit expression and intuitive image presented. Moreover, the inversion curves showing the relation between the inversion temperature and the inversion pressure are studied. It is shown that for given inversion pressure, the inversion temperature of the case $\alpha\neq0$ ($\alpha$ is the Lovelock parameter) is much lower than that of the case $\alpha=0$. And the inversion temperature tends to decrease with $\alpha$, in contrast to the effect of the electric charge. It is also shown that the ratio between the minimum inversion temperature and the critical temperature decreases with $\alpha$ for $\alpha\neq0$. Furthermore, the isenthalpic curves are investigated with rich physics revealed. The intersection point between the isenthalpic curve and the inversion curve is exactly the inversion point discriminating the heating process from cooling process. It is shown that both the inversion temperature and the inversion pressure for $\alpha\neq0$ are much lower for the same given mass of the black hole, showing the effect of Lovelock gravity. Last but not the least, we discuss the case of uncharged Lovelock AdS black holes with interesting feature found. It is shown that the Joule-Thomson coefficient is always positive, suggesting the expansion is always in the regime of cooling process. And no inversion temperature exists, in contrast to the case $Q\neq0$. Isenthalpic curves are also quite different since the temperature increases monotonically with the pressure when the mass is specified. |
2011.10179 | Chen Zhang | Bob Holdom, Robert B. Mann, Chen Zhang | Unruh-DeWitt Detector Differentiation of Black Holes and Exotic Compact
Objects | 18 pages, 22 figures | Phys. Rev. D 103, 124046 (2021) | 10.1103/PhysRevD.103.124046 | null | gr-qc astro-ph.HE quant-ph | http://creativecommons.org/licenses/by/4.0/ | We study the response of a static Unruh-DeWitt detector outside an exotic
compact object (ECO) with a general reflective boundary condition in 3+1
dimensions. The horizonless ECO, whose boundary is extremely close to the
would-be event horizon, acts as a black hole mimicker. We find that the
response rate is notably distinct from the black hole case, even when the ECO
boundary is perfectly absorbing. For a (partially) reflective ECO boundary, we
find resonance structures in the response rate that depend on the different
locations of the ECO boundary and those of the detector. We provide a detailed
analysis in connection with the ECO's vacuum mode structure and transfer
function.
| [
{
"created": "Fri, 20 Nov 2020 02:33:04 GMT",
"version": "v1"
}
] | 2021-06-30 | [
[
"Holdom",
"Bob",
""
],
[
"Mann",
"Robert B.",
""
],
[
"Zhang",
"Chen",
""
]
] | We study the response of a static Unruh-DeWitt detector outside an exotic compact object (ECO) with a general reflective boundary condition in 3+1 dimensions. The horizonless ECO, whose boundary is extremely close to the would-be event horizon, acts as a black hole mimicker. We find that the response rate is notably distinct from the black hole case, even when the ECO boundary is perfectly absorbing. For a (partially) reflective ECO boundary, we find resonance structures in the response rate that depend on the different locations of the ECO boundary and those of the detector. We provide a detailed analysis in connection with the ECO's vacuum mode structure and transfer function. |
0901.1079 | Steven Willison | E. Gravanis and S. Willison | Singular sources in gravity and homotopy in the space of connections | 21 pages, 9 figures, RevTeX | J.Math.Phys.50:122505,2009 | 10.1063/1.3250196 | CECS-PHY-09/01 | gr-qc hep-th math.AT | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Suppose a Lagrangian is constructed from its fields and their derivatives.
When the field configuration is a distribution, it is unambiguously defined as
the limit of a sequence of smooth fields. The Lagrangian may or may not be a
distribution, depending on whether there is some undefined product of
distributions. Supposing that the Lagrangian is a distribution, it is
unambiguously defined as the limit of a sequence of Lagrangians. But there
still remains the question: Is the distributional Lagrangian uniquely defined
by the limiting process for the fields themselves? In this paper a general
geometrical construction is advanced to address this question. We describe
certain types of singularities, not by distribution valued tensors, but by
showing that the action functional for the singular fields is (formally)
equivalent to another action built out of \emph{smooth} fields. Thus we manage
to make the problem of the lack of a derivative disappear from a system which
gives differential equations. Certain ideas from homotopy and homology theory
turn out to be of central importance in analyzing the problem and clarifying
finer aspects of it.
The method is applied to general relativity in first order formalism, which
gives some interesting insights into distributional geometries in that theory.
Then more general gravitational Lagrangians in first order formalism are
considered such as Lovelock terms (for which the action principle admits
space-times more singular than other higher curvature theories).
| [
{
"created": "Thu, 8 Jan 2009 16:47:10 GMT",
"version": "v1"
}
] | 2010-01-15 | [
[
"Gravanis",
"E.",
""
],
[
"Willison",
"S.",
""
]
] | Suppose a Lagrangian is constructed from its fields and their derivatives. When the field configuration is a distribution, it is unambiguously defined as the limit of a sequence of smooth fields. The Lagrangian may or may not be a distribution, depending on whether there is some undefined product of distributions. Supposing that the Lagrangian is a distribution, it is unambiguously defined as the limit of a sequence of Lagrangians. But there still remains the question: Is the distributional Lagrangian uniquely defined by the limiting process for the fields themselves? In this paper a general geometrical construction is advanced to address this question. We describe certain types of singularities, not by distribution valued tensors, but by showing that the action functional for the singular fields is (formally) equivalent to another action built out of \emph{smooth} fields. Thus we manage to make the problem of the lack of a derivative disappear from a system which gives differential equations. Certain ideas from homotopy and homology theory turn out to be of central importance in analyzing the problem and clarifying finer aspects of it. The method is applied to general relativity in first order formalism, which gives some interesting insights into distributional geometries in that theory. Then more general gravitational Lagrangians in first order formalism are considered such as Lovelock terms (for which the action principle admits space-times more singular than other higher curvature theories). |
0812.1590 | Neil J. Cornish | Joey Shapiro Key and Neil J. Cornish | Characterizing the Gravitational Wave Signature from Cosmic String Cusps | 10 pages, 10 figures | Phys.Rev.D79:043014,2009 | 10.1103/PhysRevD.79.043014 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Cosmic strings are predicted to form kinks and cusps that travel along the
string at close to the speed of light. These disturbances are radiated away as
highly beamed gravitational waves that produce a burst like pulse as the cone
of emission sweeps past an observer. Gravitational wave detectors such as the
Laser Interferometer Space Antenna (LISA) and the Laser Interferometer
Gravitational wave Observatory (LIGO) will be capable of detecting these bursts
for a wide class of string models. Such a detection would illuminate the fields
of string theory, cosmology, and relativity. Here we develop template based
Markov Chain Monte Carlo (MCMC) techniques that can efficiently detect and
characterize the signals from cosmic string cusps. We estimate how well the
signal parameters can be recovered by the advanced LIGO-Virgo network and the
LISA detector using a combination of MCMC and Fisher matrix techniques. We also
consider joint detections by the ground and space based instruments. We show
that a parallel tempered MCMC approach can detect and characterize the signals
from cosmic string cusps, and we demonstrate the utility of this approach on
simulated data from the third round of Mock LISA Data Challenges (MLDCs).
| [
{
"created": "Mon, 8 Dec 2008 23:15:20 GMT",
"version": "v1"
}
] | 2010-04-30 | [
[
"Key",
"Joey Shapiro",
""
],
[
"Cornish",
"Neil J.",
""
]
] | Cosmic strings are predicted to form kinks and cusps that travel along the string at close to the speed of light. These disturbances are radiated away as highly beamed gravitational waves that produce a burst like pulse as the cone of emission sweeps past an observer. Gravitational wave detectors such as the Laser Interferometer Space Antenna (LISA) and the Laser Interferometer Gravitational wave Observatory (LIGO) will be capable of detecting these bursts for a wide class of string models. Such a detection would illuminate the fields of string theory, cosmology, and relativity. Here we develop template based Markov Chain Monte Carlo (MCMC) techniques that can efficiently detect and characterize the signals from cosmic string cusps. We estimate how well the signal parameters can be recovered by the advanced LIGO-Virgo network and the LISA detector using a combination of MCMC and Fisher matrix techniques. We also consider joint detections by the ground and space based instruments. We show that a parallel tempered MCMC approach can detect and characterize the signals from cosmic string cusps, and we demonstrate the utility of this approach on simulated data from the third round of Mock LISA Data Challenges (MLDCs). |
1307.0377 | Spiros Cotsakis | Spiros Cotsakis, Georgia Kittou | Flat limits of curved interacting cosmic fluids | v2: 26 pages, new mathematical appendix, improved readability,
version to appear in Phys. Rev. D | Phys. Rev. D 88, 083514 (2013) | 10.1103/PhysRevD.88.083514 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study curved isotropic cosmologies filled with two interacting fluids near
their time singularities. We find that a number of these universes asymptote to
flat limits in the sense that their asymptotic properties become
indistinguishable from those of flat Friedmann-Robertson-Walker models on
approach to the singularity along any asymptotic direction. In particular,
there are no essential singularities in these models. We discuss connections of
this result with possible extensions of the cosmic no hair theorem to the case
of two interacting fluids, and also provide links to a quantum cosmological
treatment of real and complex Euclidean such solutions.
| [
{
"created": "Mon, 1 Jul 2013 14:26:03 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Oct 2013 07:50:19 GMT",
"version": "v2"
}
] | 2013-10-30 | [
[
"Cotsakis",
"Spiros",
""
],
[
"Kittou",
"Georgia",
""
]
] | We study curved isotropic cosmologies filled with two interacting fluids near their time singularities. We find that a number of these universes asymptote to flat limits in the sense that their asymptotic properties become indistinguishable from those of flat Friedmann-Robertson-Walker models on approach to the singularity along any asymptotic direction. In particular, there are no essential singularities in these models. We discuss connections of this result with possible extensions of the cosmic no hair theorem to the case of two interacting fluids, and also provide links to a quantum cosmological treatment of real and complex Euclidean such solutions. |
2210.17387 | Francisco Lobo | Marzieh Peyravi, Samira Nazifkar, Francisco S. N. Lobo, Kurosh Javidan | Thick branes via higher order field theory models with exponential and
power-law tails | 23 pages, 10 figures. V2: 25 pages; 12 figures; matches published
version. arXiv admin note: text overlap with arXiv:1504.04603 | Eur. Phys. J. C 83, 832 (2023) | 10.1140/epjc/s10052-023-11992-z | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we obtain exact thick brane models in $4+1$ dimensions
generated by higher order field theory kinks, inspired by specific potentials
for $\phi^{10}$ and $\phi^{18}$ models. We verify that the geodesic equation
along the fifth dimension confirms the confining effects of the scalar field on
the brane for all of these models. These models provide new solutions with
exponential and power-law tails which live in different topological sectors. We
show that the resulting branes of specific exponential law models do not
possess $Z_2$-symmetry. Furthermore, we examine the stability of the thick
branes, by determining the sign of the $w^2$ term in the expansion of the
potential for the resulting Schr\"{o}dinger-like equation. It turns out that
two of the three models of the $\phi^{10}$ brane are stable, while another
contains unstable modes for certain ranges of the model parameters. We also
show that the brane solution from the specific $\phi^{18}$ models are stable,
while the others involve neutral equilibrium. The asymptotic behaviour of the
brane solutions are also discussed.
| [
{
"created": "Mon, 31 Oct 2022 15:13:42 GMT",
"version": "v1"
},
{
"created": "Thu, 21 Sep 2023 17:08:09 GMT",
"version": "v2"
}
] | 2023-09-22 | [
[
"Peyravi",
"Marzieh",
""
],
[
"Nazifkar",
"Samira",
""
],
[
"Lobo",
"Francisco S. N.",
""
],
[
"Javidan",
"Kurosh",
""
]
] | In this work, we obtain exact thick brane models in $4+1$ dimensions generated by higher order field theory kinks, inspired by specific potentials for $\phi^{10}$ and $\phi^{18}$ models. We verify that the geodesic equation along the fifth dimension confirms the confining effects of the scalar field on the brane for all of these models. These models provide new solutions with exponential and power-law tails which live in different topological sectors. We show that the resulting branes of specific exponential law models do not possess $Z_2$-symmetry. Furthermore, we examine the stability of the thick branes, by determining the sign of the $w^2$ term in the expansion of the potential for the resulting Schr\"{o}dinger-like equation. It turns out that two of the three models of the $\phi^{10}$ brane are stable, while another contains unstable modes for certain ranges of the model parameters. We also show that the brane solution from the specific $\phi^{18}$ models are stable, while the others involve neutral equilibrium. The asymptotic behaviour of the brane solutions are also discussed. |
gr-qc/9708055 | Hitoshi Kitada | Hitoshi Kitada (Univ. of Tokyo & Univ. of Virginia) and Lancelot R.
Fletcher (The Free Lance Academy) | Comments on the Problem of Time | 6 pages, LaTeX, the arguments are strengthened with a mathematical
theorem | null | null | KIMS-1997-08-22 | gr-qc | null | The problem of time, considered as a problem in the usual physical context,
is reflected in relation with the paper by Kauffman and Smolin (gr-qc/9703026).
It is shown that the problem is a misposed problem in the sense that it was
raised with a lack of the recognition of mathematically known facts.
| [
{
"created": "Fri, 22 Aug 1997 17:25:09 GMT",
"version": "v1"
},
{
"created": "Sat, 23 Aug 1997 03:59:53 GMT",
"version": "v2"
},
{
"created": "Wed, 3 Sep 1997 18:34:15 GMT",
"version": "v3"
},
{
"created": "Sat, 1 Nov 1997 09:33:51 GMT",
"version": "v4"
}
] | 2008-02-03 | [
[
"Kitada",
"Hitoshi",
"",
"Univ. of Tokyo & Univ. of Virginia"
],
[
"Fletcher",
"Lancelot R.",
"",
"The Free Lance Academy"
]
] | The problem of time, considered as a problem in the usual physical context, is reflected in relation with the paper by Kauffman and Smolin (gr-qc/9703026). It is shown that the problem is a misposed problem in the sense that it was raised with a lack of the recognition of mathematically known facts. |
gr-qc/9509031 | Piljin Yi | Piljin Yi | Quenched Hawking Radiation and the Black Hole Pair-Creation Rate | LaTeX, 18 pages, 5 .eps figures (to appear in the proceedings of the
Sixth Moscow Quantum Gravity Seminar, June 12-19, 1995) | null | null | CU-TP-702 | gr-qc hep-th | null | The main topic of this talk is the Hawking effect when the black holes in
question are undergoing a uniform acceleration. The semiclassical effect of the
acceleration is most striking when the Hawking temperature equals the
acceleration temperature. Within the usual late-time approximation, the natural
black hole vacuum is then equivalent to the asymptotically empty Minkowskian
vacuum, and the accelerated black hole becomes semiclassically stable against
the familiar thermal evaporation. An important application of this phenomenon
is found in the problem of charged black hole pair-creation.
| [
{
"created": "Tue, 19 Sep 1995 11:18:50 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Yi",
"Piljin",
""
]
] | The main topic of this talk is the Hawking effect when the black holes in question are undergoing a uniform acceleration. The semiclassical effect of the acceleration is most striking when the Hawking temperature equals the acceleration temperature. Within the usual late-time approximation, the natural black hole vacuum is then equivalent to the asymptotically empty Minkowskian vacuum, and the accelerated black hole becomes semiclassically stable against the familiar thermal evaporation. An important application of this phenomenon is found in the problem of charged black hole pair-creation. |
gr-qc/9902073 | Shahar Hod | Shahar Hod | Mode-coupling in rotating gravitational collapse: Gravitational and
electromagnetic perturbations | 16 pages | Phys. Rev. D 61, 064018 (2000) | 10.1103/PhysRevD.61.064018 | null | gr-qc | null | We consider the late-time evolution of {\it gravitational} and
electromagnetic perturbations in realistic {\it rotating} Kerr spacetimes. We
give a detailed analysis of the mode-coupling phenomena in rotating
gravitational collapse. A consequence of this phenomena is that the late-time
tail is dominated by modes which, in general, may have an angular distribution
different from the original one. In addition, we show that different types of
fields have {\it different} decaying rates. This result turns over the
traditional belief (which has been widely accepted during the last three
decades) that the late-time tail of gravitational collapse is universal.
| [
{
"created": "Tue, 23 Feb 1999 14:07:42 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Mar 2000 07:49:30 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Hod",
"Shahar",
""
]
] | We consider the late-time evolution of {\it gravitational} and electromagnetic perturbations in realistic {\it rotating} Kerr spacetimes. We give a detailed analysis of the mode-coupling phenomena in rotating gravitational collapse. A consequence of this phenomena is that the late-time tail is dominated by modes which, in general, may have an angular distribution different from the original one. In addition, we show that different types of fields have {\it different} decaying rates. This result turns over the traditional belief (which has been widely accepted during the last three decades) that the late-time tail of gravitational collapse is universal. |
0809.3218 | David Garfinkle | Jim Isenberg (University of Oregon), Lyman Page (Princeton
University), Maria Alessandra Papa (Albert Einstein Institute), Edward K.
Porter (Albert Einstein Institute) | Matters of Gravity, The Newsletter of the Topical Group in Gravitation
of the American Physical Society, Volume 32, Fall 2008 | 19 pages, 3 figures, latex; Edited by David Garfinkle and Greg Comer | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | GGR News:
- Remembering Wheeler, by Jim Isenberg;
Research Briefs:
- A Brief Summary of the WMAP5 Results, by Lyman Page;
- Science with LIGO, by Maria Alessandra Papa;
Conference Reports:
- 7th LISA Symposium, by Edward K. Porter;
- The Fourth Gulf Coast Gravity Conference, by Lior Burko
| [
{
"created": "Thu, 18 Sep 2008 18:09:23 GMT",
"version": "v1"
}
] | 2008-12-01 | [
[
"Isenberg",
"Jim",
"",
"University of Oregon"
],
[
"Page",
"Lyman",
"",
"Princeton\n University"
],
[
"Papa",
"Maria Alessandra",
"",
"Albert Einstein Institute"
],
[
"Porter",
"Edward K.",
"",
"Albert Einstein Institute"
]
] | GGR News: - Remembering Wheeler, by Jim Isenberg; Research Briefs: - A Brief Summary of the WMAP5 Results, by Lyman Page; - Science with LIGO, by Maria Alessandra Papa; Conference Reports: - 7th LISA Symposium, by Edward K. Porter; - The Fourth Gulf Coast Gravity Conference, by Lior Burko |
1710.10961 | Rong-Jia Yang | Rong-Jia Yang | Gravitational waves in conformal gravity | 8 pages, no figures, some errors are corrected | Phys. Lett. B 784 (2018) 212-216 | 10.1016/j.physletb.2018.08.002 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the gravitational radiation in conformal gravity theory. We
perturb the metric from flat Mikowski space and obtain the wave equation after
introducing the appropriate transformation for perturbation. We derive the
effective energy-momentum tensor for the gravitational radiation, which can be
used to determine the energy carried by gravitational waves.
| [
{
"created": "Mon, 30 Oct 2017 14:16:47 GMT",
"version": "v1"
},
{
"created": "Tue, 24 Apr 2018 12:55:47 GMT",
"version": "v2"
},
{
"created": "Sat, 25 Aug 2018 14:20:48 GMT",
"version": "v3"
}
] | 2018-08-28 | [
[
"Yang",
"Rong-Jia",
""
]
] | We consider the gravitational radiation in conformal gravity theory. We perturb the metric from flat Mikowski space and obtain the wave equation after introducing the appropriate transformation for perturbation. We derive the effective energy-momentum tensor for the gravitational radiation, which can be used to determine the energy carried by gravitational waves. |
1901.05648 | Sebastian Schuster | Sebastian Schuster (Victoria University of Wellington) | Black Hole Evaporation: Sparsity in Analogue and General Relativistic
Space-Times | PhD Thesis (Victoria University of Wellington), xiv+226 pages, 13
figures, 5 tables, parts already published in arXiv:1808.07987,
arXiv:1802.09807, arXiv:1801.05549, arXiv:1706.06280, arXiv:1610.06135,
arXiv:1506.03975 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Our understanding of black holes changed drastically, when Stephen Hawking
discovered their evaporation due to quantum mechanical processes. One core
feature of this effect is both its similarity and simultaneous dissimilarity to
classical black body radiation: A black hole's spectrum certainly looks like
that of a black/grey body, yet the number of emitted particles per unit time
differs greatly. However it is precisely this emission rate that determines
whether the resulting radiation field behaves classically or non-classically.
It has been known nearly since the effect's discovery that a black hole's
radiation is in this sense non-classical. However, this has been an utterly
underappreciated property. In order to give a more readily quantifiable picture
of this, we introduced the easily evaluated and interpreted notion of
"sparsity". Sadly, and much to relativists' chagrin, astrophysical black holes
(and their evaporation) tend to be observationally elusive entities. Luckily,
Hawking's derivation lends itself to reformulations that survive outside its
astrophysical origin - only three things are needed: a universal speed limit, a
notion of a horizon, and lastly a sprinkle of quantum dynamics on top. With
these ingredients at hand, the last thirty-odd years have seen a lot of work to
transfer Hawking radiation into the laboratory, using a range of physical
models. A large part of this thesis is aimed at providing electromagnetic
analogues to prepare an analysis of our notion of sparsity in these analogues.
For this, we developed extensively a purely algebraic/kinematical analogy based
on covariant meta-material electrodynamics, but also an analytic/dynamical
analogy based on stratified refractive indices. After introducing these
analogue space-time models, we explain why the notion of sparsity is much more
subtle and difficult to come by than in the original, astrophysical setting.
| [
{
"created": "Thu, 17 Jan 2019 07:06:22 GMT",
"version": "v1"
}
] | 2019-01-18 | [
[
"Schuster",
"Sebastian",
"",
"Victoria University of Wellington"
]
] | Our understanding of black holes changed drastically, when Stephen Hawking discovered their evaporation due to quantum mechanical processes. One core feature of this effect is both its similarity and simultaneous dissimilarity to classical black body radiation: A black hole's spectrum certainly looks like that of a black/grey body, yet the number of emitted particles per unit time differs greatly. However it is precisely this emission rate that determines whether the resulting radiation field behaves classically or non-classically. It has been known nearly since the effect's discovery that a black hole's radiation is in this sense non-classical. However, this has been an utterly underappreciated property. In order to give a more readily quantifiable picture of this, we introduced the easily evaluated and interpreted notion of "sparsity". Sadly, and much to relativists' chagrin, astrophysical black holes (and their evaporation) tend to be observationally elusive entities. Luckily, Hawking's derivation lends itself to reformulations that survive outside its astrophysical origin - only three things are needed: a universal speed limit, a notion of a horizon, and lastly a sprinkle of quantum dynamics on top. With these ingredients at hand, the last thirty-odd years have seen a lot of work to transfer Hawking radiation into the laboratory, using a range of physical models. A large part of this thesis is aimed at providing electromagnetic analogues to prepare an analysis of our notion of sparsity in these analogues. For this, we developed extensively a purely algebraic/kinematical analogy based on covariant meta-material electrodynamics, but also an analytic/dynamical analogy based on stratified refractive indices. After introducing these analogue space-time models, we explain why the notion of sparsity is much more subtle and difficult to come by than in the original, astrophysical setting. |
2105.11380 | Adri\'an Del R\'io Vega | Ivan Agullo, Vitor Cardoso, Adri\'an del Rio, Michele Maggiore, Jorge
Pullin | Absorption spectroscopy of quantum black holes with gravitational waves | Received honorable mention at the GRF essay competition of 2021 | null | 10.1142/S021827182142013X | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The observation of electromagnetic radiation emitted or absorbed by matter
was instrumental in revealing the quantum properties of atoms and molecules in
the early XX century, and constituted a turning-point in the development of the
quantum theory. Quantum mechanics changes dramatically the way radiation and
matter interact, making the probability of emission and absorption of light
strongly frequency dependent, as clearly manifested in atomic spectra. In this
essay, we advocate that gravitational radiation can play, for the quantum
aspects of black holes, a similar role as electromagnetic radiation did for
atoms, and that the advent of gravitational-wave astronomy can bring this
fascinating possibility to the realm of observations.
| [
{
"created": "Mon, 24 May 2021 16:18:01 GMT",
"version": "v1"
}
] | 2022-01-26 | [
[
"Agullo",
"Ivan",
""
],
[
"Cardoso",
"Vitor",
""
],
[
"del Rio",
"Adrián",
""
],
[
"Maggiore",
"Michele",
""
],
[
"Pullin",
"Jorge",
""
]
] | The observation of electromagnetic radiation emitted or absorbed by matter was instrumental in revealing the quantum properties of atoms and molecules in the early XX century, and constituted a turning-point in the development of the quantum theory. Quantum mechanics changes dramatically the way radiation and matter interact, making the probability of emission and absorption of light strongly frequency dependent, as clearly manifested in atomic spectra. In this essay, we advocate that gravitational radiation can play, for the quantum aspects of black holes, a similar role as electromagnetic radiation did for atoms, and that the advent of gravitational-wave astronomy can bring this fascinating possibility to the realm of observations. |
2110.06469 | Kiyoshi Shiraishi | Nahomi Kan, Takuma Aoyama, Taiga Hasegawa, Kiyoshi Shiraishi | Third quantization for scalar and spinor wave functions of the Universe
in an extended minisuperspace | 19 pages, 2 figures. revised version 2 | Class. Quant. Grav. 39 (2022) 165010 | 10.1088/1361-6382/ac8095 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We consider the third quantization in quantum cosmology of a minisuperspace
extended by the Eisenhart-Duval lift. We study the third quantization based on
both Klein-Gordon type and Dirac-type equations in the extended minisuperspace.
Spontaneous creation of "universes" is investigated upon the quantization of a
simple model. We find that the quantization of the Dirac-type wave function
reveals that the number density of universes is expressed by the Fermi-Dirac
distribution. We also calculate the entanglement entropy of the multi-universe
system.
| [
{
"created": "Wed, 13 Oct 2021 03:12:15 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Oct 2021 00:27:17 GMT",
"version": "v2"
},
{
"created": "Wed, 23 Feb 2022 00:34:48 GMT",
"version": "v3"
},
{
"created": "Fri, 13 May 2022 00:24:49 GMT",
"version": "v4"
},
{
"created": "Sun, 3 Jul 2022 06:00:16 GMT",
"version": "v5"
}
] | 2022-08-23 | [
[
"Kan",
"Nahomi",
""
],
[
"Aoyama",
"Takuma",
""
],
[
"Hasegawa",
"Taiga",
""
],
[
"Shiraishi",
"Kiyoshi",
""
]
] | We consider the third quantization in quantum cosmology of a minisuperspace extended by the Eisenhart-Duval lift. We study the third quantization based on both Klein-Gordon type and Dirac-type equations in the extended minisuperspace. Spontaneous creation of "universes" is investigated upon the quantization of a simple model. We find that the quantization of the Dirac-type wave function reveals that the number density of universes is expressed by the Fermi-Dirac distribution. We also calculate the entanglement entropy of the multi-universe system. |
1409.1782 | Roland Steinbauer | Jiri Podolsky, Clemens S\"amann, Roland Steinbauer, Robert Svarc | The global existence, uniqueness and C^1-regularity of geodesics in
nonexpanding impulsive gravitational waves | 20 pages, 1 figure, minor revisions, final version | Class.Quant.Grav.32:025003,2015 | 10.1088/0264-9381/32/2/025003 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study geodesics in the complete family of nonexpanding impulsive
gravitational waves propagating in spaces of constant curvature, that is
Minkowski, de Sitter and anti-de Sitter universes. Employing the continuous
form of the metric we prove existence and uniqueness of continuously
differentiable geodesics (in the sense of Filippov) and use a C^1-matching
procedure to explicitly derive their form.
| [
{
"created": "Fri, 5 Sep 2014 13:12:02 GMT",
"version": "v1"
},
{
"created": "Thu, 29 Jan 2015 10:55:25 GMT",
"version": "v2"
}
] | 2015-01-30 | [
[
"Podolsky",
"Jiri",
""
],
[
"Sämann",
"Clemens",
""
],
[
"Steinbauer",
"Roland",
""
],
[
"Svarc",
"Robert",
""
]
] | We study geodesics in the complete family of nonexpanding impulsive gravitational waves propagating in spaces of constant curvature, that is Minkowski, de Sitter and anti-de Sitter universes. Employing the continuous form of the metric we prove existence and uniqueness of continuously differentiable geodesics (in the sense of Filippov) and use a C^1-matching procedure to explicitly derive their form. |
2403.13662 | Xiaoning Wu | Qin Liu, Xiaoning Wu and Xiao Zhang | Phase transition of modified thermodynamics of the Kerr-AdS black hole | 17 pages, 4 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We investigate the critical phenomena of Kerr-AdS black holes in the modified
first law of thermodynamics. It is demonstrated that the modified black hole
thermodynamics exhibits a van derWaals-like phase structure, with different
free energy.
| [
{
"created": "Wed, 20 Mar 2024 15:13:09 GMT",
"version": "v1"
}
] | 2024-03-21 | [
[
"Liu",
"Qin",
""
],
[
"Wu",
"Xiaoning",
""
],
[
"Zhang",
"Xiao",
""
]
] | We investigate the critical phenomena of Kerr-AdS black holes in the modified first law of thermodynamics. It is demonstrated that the modified black hole thermodynamics exhibits a van derWaals-like phase structure, with different free energy. |
gr-qc/9308009 | Dalia Goldwirth | Dalia S. Goldwirth, Malcolm J. Perry, Tsvi Piran and Kip S. Thorne | The Quantum Propagator for a Nonrelativistic Particle in the Vicinity of
a Time Machine | null | Phys.Rev. D49 (1994) 3951-3957 | 10.1103/PhysRevD.49.3951 | null | gr-qc astro-ph hep-th | null | We study the propagator of a non-relativistic, non-interacting particle in
any non-relativistic ``time-machine'' spacetime of the type shown in Fig.~1: an
external, flat spacetime in which two spatial regions, $V_-$ at time $t_-$ and
$V_+$ at time $t_+$, are connected by two temporal wormholes, one leading from
the past side of $V_-$ to t the future side of $V_+$ and the other from the
past side of $V_+$ to the future side of $V_-$. We express the propagator
explicitly in terms of those for ordinary, flat spacetime and for the two
wormholes; and from that expression we show that the propagator satisfies
completeness and unitarity in the initial and final ``chronal regions''
(regions without closed timelike curves) and its propagation from the initial
region to the final region is unitary. However, within the time machine it
satisfies neither completeness nor unitarity. We also give an alternative proof
of initial-region-to-final-region unitarity based on a conserved current and
Gauss's theorem. This proof can be carried over without change to most any
non-relativistic time-machine spacetime; it is the non-relativistic version of
a theorem by Friedman, Papastamatiou and Simon, which says that for a free
scalar field, quantum mechanical unitarity follows from the fact that the
classical evolution preserves the Klein-Gordon inner product.
| [
{
"created": "Tue, 10 Aug 1993 16:29:23 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Goldwirth",
"Dalia S.",
""
],
[
"Perry",
"Malcolm J.",
""
],
[
"Piran",
"Tsvi",
""
],
[
"Thorne",
"Kip S.",
""
]
] | We study the propagator of a non-relativistic, non-interacting particle in any non-relativistic ``time-machine'' spacetime of the type shown in Fig.~1: an external, flat spacetime in which two spatial regions, $V_-$ at time $t_-$ and $V_+$ at time $t_+$, are connected by two temporal wormholes, one leading from the past side of $V_-$ to t the future side of $V_+$ and the other from the past side of $V_+$ to the future side of $V_-$. We express the propagator explicitly in terms of those for ordinary, flat spacetime and for the two wormholes; and from that expression we show that the propagator satisfies completeness and unitarity in the initial and final ``chronal regions'' (regions without closed timelike curves) and its propagation from the initial region to the final region is unitary. However, within the time machine it satisfies neither completeness nor unitarity. We also give an alternative proof of initial-region-to-final-region unitarity based on a conserved current and Gauss's theorem. This proof can be carried over without change to most any non-relativistic time-machine spacetime; it is the non-relativistic version of a theorem by Friedman, Papastamatiou and Simon, which says that for a free scalar field, quantum mechanical unitarity follows from the fact that the classical evolution preserves the Klein-Gordon inner product. |
0908.3573 | Tomasz Konopka | Tomasz Konopka | Static Isotropic Spacetimes with Radially Imperfect Fluids | 15 pages, 4 figures. Accepted in IJMPD | null | 10.1142/S0218271809015345 | SPIN 09/26, ITP-UU 09/30 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | When solving the equations of General Relativity in a symmetric sector, it is
natural to consider the same symmetry for the geometry and stress-energy. This
implies that for static and isotropic spacetimes, the most general natural
stress-energy tensor is a sum of a perfect fluid and a radial imperfect fluid
component. In the special situations where the perfect fluid component vanishes
or is a spacetime constant, the solutions to Einstein's equations can be
thought of as modified Schwarzschild and Schwarzschild-de Sitter spaces. Exact
solutions of this type are derived and it is shown that whereas deviations from
the unmodified solutions can be made small, among the manifestations of the
imperfect fluid component is a shift in angular momentum scaling for orbiting
test-bodies at large radius. Based on this effect, the question of whether the
imperfect fluid component can feasibly describe dark matter phenomenology is
addressed.
| [
{
"created": "Tue, 25 Aug 2009 09:09:57 GMT",
"version": "v1"
}
] | 2015-05-14 | [
[
"Konopka",
"Tomasz",
""
]
] | When solving the equations of General Relativity in a symmetric sector, it is natural to consider the same symmetry for the geometry and stress-energy. This implies that for static and isotropic spacetimes, the most general natural stress-energy tensor is a sum of a perfect fluid and a radial imperfect fluid component. In the special situations where the perfect fluid component vanishes or is a spacetime constant, the solutions to Einstein's equations can be thought of as modified Schwarzschild and Schwarzschild-de Sitter spaces. Exact solutions of this type are derived and it is shown that whereas deviations from the unmodified solutions can be made small, among the manifestations of the imperfect fluid component is a shift in angular momentum scaling for orbiting test-bodies at large radius. Based on this effect, the question of whether the imperfect fluid component can feasibly describe dark matter phenomenology is addressed. |
1301.3291 | Giovanni Acquaviva | Giovanni Acquaviva | Quantum fields in gravity | 4 pages, no figures, contribution to the proceedings of the
conference "Relativity and Gravitation - 100 years after Einstein in Prague" | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We give a brief description of some compelling connections between general
relativity and thermodynamics through i) the semi-classical tunnelling
method(s) and ii) the field-theoretical modelling of Unruh-DeWitt detectors. In
both approaches it is possible to interpret some quantities in a
thermodynamical frame.
| [
{
"created": "Tue, 15 Jan 2013 10:22:07 GMT",
"version": "v1"
}
] | 2013-01-16 | [
[
"Acquaviva",
"Giovanni",
""
]
] | We give a brief description of some compelling connections between general relativity and thermodynamics through i) the semi-classical tunnelling method(s) and ii) the field-theoretical modelling of Unruh-DeWitt detectors. In both approaches it is possible to interpret some quantities in a thermodynamical frame. |
gr-qc/0202048 | Carlos Palenzuela | C.Bona and C.Palenzuela | Explicit Gravitational Radiation in Hyperbolic Systems for Numerical
Relativity | 9 pages, no figures | null | null | null | gr-qc | null | A method for studying the causal structure of space-time evolution systems is
presented. This method, based on a generalization of the well known Riemann
problem, provides intrinsic results which can be interpreted from the
geometrical point of view. A one-parameter family of hyperbolic evolution
systems is presented and the physical relevance of their characteristic speeds
and eigenfields is discussed. The two degrees of freedom corresponding to
gravitational radiation are identified in an intrinsic way, independent of the
space coordinate system. A covariant interpretation of these degrees of freedom
is provided in terms of the geometry of the wave fronts. The requirement of a
consistent geometrical interpretation of the gravitational radiation degrees of
freedom is used to solve the ordering ambiguity that arises when obtaining
first order evolution systems from the second order field equations. This
achievement provides a benchmark which can be used to check both the existing
and future first order hyperbolic formalisms for Numerical Relativity.
| [
{
"created": "Thu, 14 Feb 2002 12:20:02 GMT",
"version": "v1"
},
{
"created": "Thu, 28 Feb 2002 15:18:13 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Bona",
"C.",
""
],
[
"Palenzuela",
"C.",
""
]
] | A method for studying the causal structure of space-time evolution systems is presented. This method, based on a generalization of the well known Riemann problem, provides intrinsic results which can be interpreted from the geometrical point of view. A one-parameter family of hyperbolic evolution systems is presented and the physical relevance of their characteristic speeds and eigenfields is discussed. The two degrees of freedom corresponding to gravitational radiation are identified in an intrinsic way, independent of the space coordinate system. A covariant interpretation of these degrees of freedom is provided in terms of the geometry of the wave fronts. The requirement of a consistent geometrical interpretation of the gravitational radiation degrees of freedom is used to solve the ordering ambiguity that arises when obtaining first order evolution systems from the second order field equations. This achievement provides a benchmark which can be used to check both the existing and future first order hyperbolic formalisms for Numerical Relativity. |
1310.5537 | Ko Sanders | Ko Sanders | On the construction of Hartle-Hawking-Israel states across a static
bifurcate Killing horizon | 50 pages, 2 figures, presented at GR20/Amaldi10 (Warsaw, 2013); v2:
filled technical gap in Sec.5, various small corrections; v3: typos
corrected, comparable to version accepted for publication, up to proofs left
to reader, style and punctuation | Lett Math Phys 105, no. 4 (2015), 575-640 | 10.1007/s11005-015-0745-2 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a linear scalar quantum field propagating in a space-time with a
static bifurcate Killing horizon and a wedge reflection. We prove the existence
of a Hadamard state which is pure, quasi-free, invariant under the Killing flow
and which restricts to a double KMS state at the inverse Hawking temperature on
the union of the exterior wedge regions. The existence of such a state was
first conjectured by Hartle and Hawking (1976) and Israel (1976) for stationary
black hole space times. Our result complements a uniqueness result of Kay and
Wald (1991), who considered a general bifurcate Killing horizon and proved that
a certain (large) subalgebra of the free field algebra admits at most one
Hadamard state which is invariant under the Killing flow. In the presence of a
wedge reflection this state reduces to a pure, quasi-free KMS state on the
smaller subalgebra associated to one of the exterior wedge regions. Our result
establishes the existence of such a state on the full algebra in the static
case. Our proof follows the arguments of Sewell (1982) and Jacobson (1994),
exploiting a Wick rotation in the Killing time coordinate to construct a
corresponding Euclidean theory. Because the Killing time coordinate is
ill-defined on the bifurcation surface we systematically replace it by a
Gaussian normal coordinate. A crucial part of our proof is to establish that
the Euclidean ground state satisfies the necessary analogs of analyticity and
reflection positivity with respect to this coordinate.
| [
{
"created": "Mon, 21 Oct 2013 13:19:34 GMT",
"version": "v1"
},
{
"created": "Thu, 11 Sep 2014 15:09:57 GMT",
"version": "v2"
},
{
"created": "Thu, 29 Jan 2015 19:41:50 GMT",
"version": "v3"
}
] | 2015-03-24 | [
[
"Sanders",
"Ko",
""
]
] | We consider a linear scalar quantum field propagating in a space-time with a static bifurcate Killing horizon and a wedge reflection. We prove the existence of a Hadamard state which is pure, quasi-free, invariant under the Killing flow and which restricts to a double KMS state at the inverse Hawking temperature on the union of the exterior wedge regions. The existence of such a state was first conjectured by Hartle and Hawking (1976) and Israel (1976) for stationary black hole space times. Our result complements a uniqueness result of Kay and Wald (1991), who considered a general bifurcate Killing horizon and proved that a certain (large) subalgebra of the free field algebra admits at most one Hadamard state which is invariant under the Killing flow. In the presence of a wedge reflection this state reduces to a pure, quasi-free KMS state on the smaller subalgebra associated to one of the exterior wedge regions. Our result establishes the existence of such a state on the full algebra in the static case. Our proof follows the arguments of Sewell (1982) and Jacobson (1994), exploiting a Wick rotation in the Killing time coordinate to construct a corresponding Euclidean theory. Because the Killing time coordinate is ill-defined on the bifurcation surface we systematically replace it by a Gaussian normal coordinate. A crucial part of our proof is to establish that the Euclidean ground state satisfies the necessary analogs of analyticity and reflection positivity with respect to this coordinate. |
1101.0364 | Yurii Ignatyev | Yurii G. Ignatyev | The Kinetics Of Nonequilibrium Universe. I. The Condition Of Local
Thermodynamical Equilibrium | 26 pages, 4 figures, 43 references | Grav.Cosmol.13:1-14,2007 | null | null | gr-qc hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In terms of fundamental principles of quantum theory of interacting particles
and relativistic kinetic theory there was carried out an analysis of the main
principle of standard cosmological scenario - the initial existence of local
thermodynamical equilibrium. It has been shown, that condition of the existence
of local thermodynamical equilibrium in Universe is determined essentially by
means of function of total cross-section of particles' interaction from the
kinematic invariant and in case of scaling's recovery in range of superhigh
energies it is initially broken.
| [
{
"created": "Sat, 1 Jan 2011 19:30:14 GMT",
"version": "v1"
}
] | 2011-06-21 | [
[
"Ignatyev",
"Yurii G.",
""
]
] | In terms of fundamental principles of quantum theory of interacting particles and relativistic kinetic theory there was carried out an analysis of the main principle of standard cosmological scenario - the initial existence of local thermodynamical equilibrium. It has been shown, that condition of the existence of local thermodynamical equilibrium in Universe is determined essentially by means of function of total cross-section of particles' interaction from the kinematic invariant and in case of scaling's recovery in range of superhigh energies it is initially broken. |
2007.09058 | Adil Belhaj | A. Belhaj, M. Benali, A. El Balali, W. El Hadri, H. El Moumni | Shadows of Charged and Rotating Black Holes with a Cosmological Constant | Latex, 17 pages, 8 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Motivated by recent astrophysical observations, we investigate the shadow
behaviors of four dimensional charged rotating black holes with a cosmological
constant. This study is made in terms of a reduced moduli space parameterized
by the charge and the rotation parameters. For a negative cosmological
constant, we analyse in some details two models dealing with Kerr-Newman and
Kerr-Sen black holes. In certain parameter regions, we find cardioid-like
(heart-shaped) shadows. For Anti de Sitter backgrounds, a comparative
discussion is provided by computing the geometrical observables and the energy
emission rate. Inspecting the effect of the cosmological constant, we obtain
conditions favoring cardioid-like shadows for (Anti) de Sitter spaces.
| [
{
"created": "Fri, 17 Jul 2020 15:34:22 GMT",
"version": "v1"
}
] | 2020-07-20 | [
[
"Belhaj",
"A.",
""
],
[
"Benali",
"M.",
""
],
[
"Balali",
"A. El",
""
],
[
"Hadri",
"W. El",
""
],
[
"Moumni",
"H. El",
""
]
] | Motivated by recent astrophysical observations, we investigate the shadow behaviors of four dimensional charged rotating black holes with a cosmological constant. This study is made in terms of a reduced moduli space parameterized by the charge and the rotation parameters. For a negative cosmological constant, we analyse in some details two models dealing with Kerr-Newman and Kerr-Sen black holes. In certain parameter regions, we find cardioid-like (heart-shaped) shadows. For Anti de Sitter backgrounds, a comparative discussion is provided by computing the geometrical observables and the energy emission rate. Inspecting the effect of the cosmological constant, we obtain conditions favoring cardioid-like shadows for (Anti) de Sitter spaces. |
gr-qc/0605020 | Kartheek Solipuram | Kartheek R Solipuram | Waves in the Griffiths-Podolsky Metric | 4 pages | null | null | null | gr-qc | null | Perturbations form an important section of black hole analyses. This paper
deals with the effect of perturbations as in the delineation of waves that
occur. It makes use of the spin coefficients from [3] to represent the general
equations of waves in an accelerating black hole proposed in [2].
| [
{
"created": "Tue, 2 May 2006 18:05:45 GMT",
"version": "v1"
},
{
"created": "Mon, 23 Oct 2006 19:02:34 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Solipuram",
"Kartheek R",
""
]
] | Perturbations form an important section of black hole analyses. This paper deals with the effect of perturbations as in the delineation of waves that occur. It makes use of the spin coefficients from [3] to represent the general equations of waves in an accelerating black hole proposed in [2]. |
1602.01825 | Lin-Qing Chen | Lin-Qing Chen | Bulk amplitude and degree of divergence in 4d spin foams | 25+7 pages, 10 figures | Phys. Rev. D 94, 104025 (2016) | 10.1103/PhysRevD.94.104025 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the 4-d holomorphic Spin Foam amplitude on arbitrary connected
2-complexes and degrees of divergence. With recently developed tools and
truncation scheme, we derive a formula for a certain class of graphs, which
allows us to write down the value of bulk amplitudes simply based on graph
properties. We then generalize the result to arbitrary connected 2-complexes
and extract a simple expression for the degree of divergence only in terms of
combinatorial properties and topological invariants. The distinct behaviors of
the model in different regions of parameter space signal phase transitions. In
the regime which is of physical interest for recovering diffeomorphsim symmetry
in the continuum limit, the most divergent configurations are melonic graphs.
We end with a discussion of physical implications.
| [
{
"created": "Thu, 4 Feb 2016 20:50:34 GMT",
"version": "v1"
}
] | 2016-11-15 | [
[
"Chen",
"Lin-Qing",
""
]
] | We study the 4-d holomorphic Spin Foam amplitude on arbitrary connected 2-complexes and degrees of divergence. With recently developed tools and truncation scheme, we derive a formula for a certain class of graphs, which allows us to write down the value of bulk amplitudes simply based on graph properties. We then generalize the result to arbitrary connected 2-complexes and extract a simple expression for the degree of divergence only in terms of combinatorial properties and topological invariants. The distinct behaviors of the model in different regions of parameter space signal phase transitions. In the regime which is of physical interest for recovering diffeomorphsim symmetry in the continuum limit, the most divergent configurations are melonic graphs. We end with a discussion of physical implications. |
0905.3686 | Mayeul Arminjon | Mayeul Arminjon and Frank Reifler | A non-uniqueness problem of the Dirac theory in a curved spacetime | 35 pages (standard article format). v4: Version accepted for
publication in Annalen der Physik: Redactional improvements and precisions
added in Section 2. Footnote added in the Conclusion, with new references.
v3: Introduction and Conclusion reinforced. References added. v2: subsection
2.3 added: the Lagrangian and the spin group. Also, added explanations on
admissible coefficient changes | Annalen Phys.523:531-551,2011 | 10.1002/andp.201100060 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Dirac equation in a curved spacetime depends on a field of coefficients
(essentially the Dirac matrices), for which a continuum of different choices
are possible. We study the conditions under which a change of the coefficient
fields leads to an equivalent Hamiltonian operator H, or to an equivalent
energy operator E. We do that for the standard version of the gravitational
Dirac equation, and for two alternative equations based on the tensor
representation of the Dirac fields. The latter equations may be defined when
the spacetime is four-dimensional, noncompact, and admits a spinor structure.
We find that, for each among the three versions of the equation, the vast
majority of the possible coefficient changes do not lead to an equivalent
operator H, nor to an equivalent operator E, whence a lack of uniqueness. In
particular, we prove that the Dirac energy spectrum is not unique. This
non-uniqueness of the energy spectrum comes from an effect of the choice of
coefficients, and applies in any given coordinates.
| [
{
"created": "Fri, 22 May 2009 13:58:43 GMT",
"version": "v1"
},
{
"created": "Thu, 10 Dec 2009 16:56:02 GMT",
"version": "v2"
},
{
"created": "Mon, 1 Mar 2010 14:32:41 GMT",
"version": "v3"
},
{
"created": "Fri, 27 May 2011 15:54:59 GMT",
"version": "v4"
}
] | 2011-07-14 | [
[
"Arminjon",
"Mayeul",
""
],
[
"Reifler",
"Frank",
""
]
] | The Dirac equation in a curved spacetime depends on a field of coefficients (essentially the Dirac matrices), for which a continuum of different choices are possible. We study the conditions under which a change of the coefficient fields leads to an equivalent Hamiltonian operator H, or to an equivalent energy operator E. We do that for the standard version of the gravitational Dirac equation, and for two alternative equations based on the tensor representation of the Dirac fields. The latter equations may be defined when the spacetime is four-dimensional, noncompact, and admits a spinor structure. We find that, for each among the three versions of the equation, the vast majority of the possible coefficient changes do not lead to an equivalent operator H, nor to an equivalent operator E, whence a lack of uniqueness. In particular, we prove that the Dirac energy spectrum is not unique. This non-uniqueness of the energy spectrum comes from an effect of the choice of coefficients, and applies in any given coordinates. |
0901.2746 | Jerzy Matyjasek | Jerzy Matyjasek and Dariusz Tryniecki | Next-to-leading term of the renormalized stress-energy tensor of the
quantized massive scalar field in Schwarzschild spacetime. The back reaction | null | Phys.Rev.D79:084017,2009 | 10.1103/PhysRevD.79.084017 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The next-to-leading term of the renormalized stress-energy tensor of the
quantized massive field with an arbitrary curvature coupling in the spacetime
of the Schwarzschild black hole is constructed. It is achieved by functional
differentiation of the DeWitt-Schwinger effective action involving coincidence
limit of the Hadamard-Minakshisundaram-DeWitt-Seely coefficients $a_{3}$ and
$a_{4}.$ The back reaction of the quantized field upon the Schwarzschild black
hole is briefly discussed.
| [
{
"created": "Sun, 18 Jan 2009 23:22:20 GMT",
"version": "v1"
}
] | 2009-11-06 | [
[
"Matyjasek",
"Jerzy",
""
],
[
"Tryniecki",
"Dariusz",
""
]
] | The next-to-leading term of the renormalized stress-energy tensor of the quantized massive field with an arbitrary curvature coupling in the spacetime of the Schwarzschild black hole is constructed. It is achieved by functional differentiation of the DeWitt-Schwinger effective action involving coincidence limit of the Hadamard-Minakshisundaram-DeWitt-Seely coefficients $a_{3}$ and $a_{4}.$ The back reaction of the quantized field upon the Schwarzschild black hole is briefly discussed. |
0710.1219 | Daniele Pranzetti | Giovanni Amelino-Camelia, Giulia Gubitosi, Antonino Marciano, Pierre
Martinetti, Flavio Mercati, Daniele Pranzetti, Ruggero Altair Tacchi | First results of the Noether theorem for Hopf-algebra spacetime
symmetries | 14 pages, Based in part on the lecture given by G.A.-C. at the 21st
Nishinomiya-Yukawa Memorial Symposium "Noncommutative geometry and quantum
spacetime in physics", but updated with the results of our recent papers
arXiv:0707.1863 arXiv:0709.2063 arXiv:0709.4600 | Prog.Theor.Phys.Suppl.171:65-78,2007 | 10.1143/PTPS.171.65 | null | gr-qc | null | We summarize here the first results obtained using a technique we recently
developed for the Noether analysis of Hopf-algebra spacetime symmetries,
including the derivation of conserved charges for field theories in
noncommutative spacetimes of canonical or kappa-Minkowski type.
| [
{
"created": "Fri, 5 Oct 2007 13:54:40 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Amelino-Camelia",
"Giovanni",
""
],
[
"Gubitosi",
"Giulia",
""
],
[
"Marciano",
"Antonino",
""
],
[
"Martinetti",
"Pierre",
""
],
[
"Mercati",
"Flavio",
""
],
[
"Pranzetti",
"Daniele",
""
],
[
"Tacchi",
"Ruggero Altair",
""
]
] | We summarize here the first results obtained using a technique we recently developed for the Noether analysis of Hopf-algebra spacetime symmetries, including the derivation of conserved charges for field theories in noncommutative spacetimes of canonical or kappa-Minkowski type. |
1106.2314 | Bibekananda Nayak jr | B. Nayak and L. P. Singh | Phantom energy accretion and primordial black holes evolution in
Brans-Dicke theory | 9 pages | Eur. Phys. J. C 71, 1837 (2011) | 10.1140/epjc/s10052-011-1837-5 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we study the evolution of primordial black holes within the
context of Brans-Dicke theory by considering the presence of a dark energy
component with a super-negative equation of state called phantom energy as a
background. Besides Hawking evaporation, here we consider two type of
accretions - radiation accretion and phantom energy accretion. We found that
radiation accretion increases the lifetime of primordial black holes whereas
phantom accretion decreases the lifespan of primordial black holes.
Investigating the competition between the radiation accretion and phantom
accretion, we got that there is an instant during the matter-dominated era
beyond which phantom accretion dominates radiation accretion. So the primordial
black holes which are formed in the later part of radiation dominated era and
in matter dominated era are evaporated at a quicker rate than the Hawking
evaporation. But for presently evaporating primordial black holes, radiation
accretion and Hawking evaporation terms are dominant over phantom accretion
term and hence presently evaporating primordial black holes are not much
affected by phantom accretion.
| [
{
"created": "Sun, 12 Jun 2011 14:46:49 GMT",
"version": "v1"
}
] | 2015-05-28 | [
[
"Nayak",
"B.",
""
],
[
"Singh",
"L. P.",
""
]
] | In this work, we study the evolution of primordial black holes within the context of Brans-Dicke theory by considering the presence of a dark energy component with a super-negative equation of state called phantom energy as a background. Besides Hawking evaporation, here we consider two type of accretions - radiation accretion and phantom energy accretion. We found that radiation accretion increases the lifetime of primordial black holes whereas phantom accretion decreases the lifespan of primordial black holes. Investigating the competition between the radiation accretion and phantom accretion, we got that there is an instant during the matter-dominated era beyond which phantom accretion dominates radiation accretion. So the primordial black holes which are formed in the later part of radiation dominated era and in matter dominated era are evaporated at a quicker rate than the Hawking evaporation. But for presently evaporating primordial black holes, radiation accretion and Hawking evaporation terms are dominant over phantom accretion term and hence presently evaporating primordial black holes are not much affected by phantom accretion. |
1807.03278 | Grigoris Panotopoulos | Grigoris Panotopoulos | Electromagnetic quasinormal modes of the nearly-extremal
higher-dimensional Schwarzschild-de Sitter black hole | Reference added | null | 10.1142/S0217732318501304 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We obtain an analytical expression for the electromagnetic quasinormal
spectrum of the higher-dimensional nearly-extremal Schwarzschild-de Sitter
black hole. The WKB method is used to verify the results, and a comparison with
known results from previous works is briefly made as well.
| [
{
"created": "Mon, 9 Jul 2018 17:21:24 GMT",
"version": "v1"
},
{
"created": "Fri, 24 Aug 2018 16:00:02 GMT",
"version": "v2"
}
] | 2018-08-27 | [
[
"Panotopoulos",
"Grigoris",
""
]
] | We obtain an analytical expression for the electromagnetic quasinormal spectrum of the higher-dimensional nearly-extremal Schwarzschild-de Sitter black hole. The WKB method is used to verify the results, and a comparison with known results from previous works is briefly made as well. |
gr-qc/9609069 | Hartmut Frommert | Hartmut Frommert, Holger Schoor, Heinz Dehnen | The cosmological background in the Higgs scalar-tensor theory without
Higgs particles | 15 pages, no figures, LaTeX 2.09 file. Submitted to Nuclear Physics B | Int.J.Theor.Phys. 38 (1999) 725-735 | null | null | gr-qc hep-th | null | The scalar background field and its consequences are discussed for the
Friedmann type cosmological solutions of the scalar-tensor theory of gravity
with the Higgs field of the Standard Model as the scalar gravitational field.
| [
{
"created": "Mon, 30 Sep 1996 11:40:47 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Frommert",
"Hartmut",
""
],
[
"Schoor",
"Holger",
""
],
[
"Dehnen",
"Heinz",
""
]
] | The scalar background field and its consequences are discussed for the Friedmann type cosmological solutions of the scalar-tensor theory of gravity with the Higgs field of the Standard Model as the scalar gravitational field. |
0706.2511 | Izzet Sakalli | I.Sakalli and M.Halilsoy | Chaos in Kundt type III Spacetimes | 4 Figures | Chin.Phys.Lett.28:070402,2011 | 10.1088/0256-307X/28/7/070402 | null | gr-qc | null | We consider geodesics motion in a particular Kundt type III spacetime in
which Einstein-Yang-Mills equations admit solutions. On a particular surface as
constraint we project the geodesics into the (x,y) plane and treat the problem
as a 2-dimensional one. Our numerical study shows that chaotic behavior emerges
under reasonable conditions.
| [
{
"created": "Sun, 17 Jun 2007 22:39:02 GMT",
"version": "v1"
}
] | 2011-07-28 | [
[
"Sakalli",
"I.",
""
],
[
"Halilsoy",
"M.",
""
]
] | We consider geodesics motion in a particular Kundt type III spacetime in which Einstein-Yang-Mills equations admit solutions. On a particular surface as constraint we project the geodesics into the (x,y) plane and treat the problem as a 2-dimensional one. Our numerical study shows that chaotic behavior emerges under reasonable conditions. |
1907.08312 | Preston Jones | Preston Jones, Douglas Singleton | Production of electromagnetic and sound radiation from gravitational
waves in core-collapse supernovae | Updated paper to include phonon production by gravitational waves.
Submitted to IJMPD | null | null | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper presents the scenario that gravitational waves, generated in
core-collapse of a pre-supernova star, can produce both electromagnetic
radiation and sound radiation as the gravitational wave propagates outward from
the collapsing core. While the energy of this co-produced electromagnetic
and/or sound radiation is orders of magnitude smaller than the initiating
gravitational radiation, the electromagnetic/sonic power may be sufficient to
re-ignite fusion outside the collapsing core. The non-equilibrium re-ignition
of fusion, in roughly the same time frame as the strongest neutrino emissions,
would change the configuration of the pre-supernova star. Although the
co-produced electromagnetic/sonic radiation is not powerful enough to
contribute directly to the supernova, the associated non-equilibrium
re-ignition of fusion could alter the state outside the core. The aim of this
paper is to argue that the effect of this hypothesized co-produced
electromagnetic/sonic radiation should be included in computational models of
core collapse supernovae.
| [
{
"created": "Thu, 18 Jul 2019 22:21:43 GMT",
"version": "v1"
},
{
"created": "Sat, 19 Aug 2023 20:38:42 GMT",
"version": "v2"
}
] | 2023-08-22 | [
[
"Jones",
"Preston",
""
],
[
"Singleton",
"Douglas",
""
]
] | This paper presents the scenario that gravitational waves, generated in core-collapse of a pre-supernova star, can produce both electromagnetic radiation and sound radiation as the gravitational wave propagates outward from the collapsing core. While the energy of this co-produced electromagnetic and/or sound radiation is orders of magnitude smaller than the initiating gravitational radiation, the electromagnetic/sonic power may be sufficient to re-ignite fusion outside the collapsing core. The non-equilibrium re-ignition of fusion, in roughly the same time frame as the strongest neutrino emissions, would change the configuration of the pre-supernova star. Although the co-produced electromagnetic/sonic radiation is not powerful enough to contribute directly to the supernova, the associated non-equilibrium re-ignition of fusion could alter the state outside the core. The aim of this paper is to argue that the effect of this hypothesized co-produced electromagnetic/sonic radiation should be included in computational models of core collapse supernovae. |
gr-qc/0012006 | Tomas Ledvinka | Jiri Bicak and Tomas Ledvinka | Electromagnetic fields around black holes and Meissner effect | 12 pages, 3 figures | Nuovo Cim.B115:739-749,2000 | null | null | gr-qc | null | The work on black holes immersed in external stationary magnetic fields is
reviewed in both test-field approximation and within exact solutions. In
particular we pay attention to the effect of the expulsion of the flux of
external fields across charged and rotating black holes which are approaching
extremal states. Recently this effect has been shown to occur for black hole
solutions in string theory and Kaluza-Klein theory.
| [
{
"created": "Fri, 1 Dec 2000 19:03:44 GMT",
"version": "v1"
}
] | 2010-11-19 | [
[
"Bicak",
"Jiri",
""
],
[
"Ledvinka",
"Tomas",
""
]
] | The work on black holes immersed in external stationary magnetic fields is reviewed in both test-field approximation and within exact solutions. In particular we pay attention to the effect of the expulsion of the flux of external fields across charged and rotating black holes which are approaching extremal states. Recently this effect has been shown to occur for black hole solutions in string theory and Kaluza-Klein theory. |
gr-qc/0404082 | Gilberto Medeiros Kremer | Gilberto M. Kremer, Daniele S. M. Alves | Palatini approach to 1/R gravity and its implications to the late
Universe | 5 pages and 2 figures. Accepted in PRD | Phys.Rev. D70 (2004) 023503 | 10.1103/PhysRevD.70.023503 | null | gr-qc | null | By applying the Palatini approach to the 1/R-gravity model it is possible to
explain the present accelerated expansion of the Universe. Investigation of the
late Universe limiting case shows that: (i) due to the curvature effects the
energy-momentum tensor of the matter field is not covariantly conserved; (ii)
however, it is possible to reinterpret the curvature corrections as sources of
the gravitational field, by defining a modified energy-momentum tensor; (iii)
with the adoption of this modified energy-momentum tensor the Einstein's field
equations are recovered with two main modifications: the first one is the
weakening of the gravitational effects of matter whereas the second is the
emergence of an effective varying "cosmological constant"; (iv) there is a
transition in the evolution of the cosmic scale factor from a power-law scaling
$a\propto t^{11/18}$ to an asymptotically exponential scaling $a\propto
\exp(t)$; (v) the energy density of the matter field scales as $\rho_m\propto
(1/a)^{36/11}$; (vi) the present age of the Universe and the
decelerated-accelerated transition redshift are smaller than the corresponding
ones in the $\Lambda$CDM model.
| [
{
"created": "Mon, 19 Apr 2004 18:54:21 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Kremer",
"Gilberto M.",
""
],
[
"Alves",
"Daniele S. M.",
""
]
] | By applying the Palatini approach to the 1/R-gravity model it is possible to explain the present accelerated expansion of the Universe. Investigation of the late Universe limiting case shows that: (i) due to the curvature effects the energy-momentum tensor of the matter field is not covariantly conserved; (ii) however, it is possible to reinterpret the curvature corrections as sources of the gravitational field, by defining a modified energy-momentum tensor; (iii) with the adoption of this modified energy-momentum tensor the Einstein's field equations are recovered with two main modifications: the first one is the weakening of the gravitational effects of matter whereas the second is the emergence of an effective varying "cosmological constant"; (iv) there is a transition in the evolution of the cosmic scale factor from a power-law scaling $a\propto t^{11/18}$ to an asymptotically exponential scaling $a\propto \exp(t)$; (v) the energy density of the matter field scales as $\rho_m\propto (1/a)^{36/11}$; (vi) the present age of the Universe and the decelerated-accelerated transition redshift are smaller than the corresponding ones in the $\Lambda$CDM model. |
1504.01138 | Antonio C. Guti\'errez-Pi\~neres | Antonio C. Guti\'errez-Pi\~neres and Abra\~ao J. S. Capistrano | Exact Relativistic Magnetized halos around Rotating Disks | New improved version | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The exact relativistic treatment of a rotating disk surrounded by a
magnetized material halo is presented. The features of the halo and disk are
described by the distributional energy-momentum tensor of a general fluid in
canonical form. All the relevant quantities and the metric and electromagnetic
potentials are exactly determined by an arbitrary harmonic function only. For
instance, the generalized Kuzmin-disk potential is used. The particular class
of solutions obtained is asymptotically flat and satisfies all the energy
conditions. Moreover, the motion of a charged particle on the halo is
described. As far as we know, this is the first relativistic model describing
analytically the magnetized halo of a rotating disk.
| [
{
"created": "Sun, 5 Apr 2015 16:58:25 GMT",
"version": "v1"
},
{
"created": "Fri, 15 May 2015 02:03:00 GMT",
"version": "v2"
}
] | 2015-05-18 | [
[
"Gutiérrez-Piñeres",
"Antonio C.",
""
],
[
"Capistrano",
"Abraão J. S.",
""
]
] | The exact relativistic treatment of a rotating disk surrounded by a magnetized material halo is presented. The features of the halo and disk are described by the distributional energy-momentum tensor of a general fluid in canonical form. All the relevant quantities and the metric and electromagnetic potentials are exactly determined by an arbitrary harmonic function only. For instance, the generalized Kuzmin-disk potential is used. The particular class of solutions obtained is asymptotically flat and satisfies all the energy conditions. Moreover, the motion of a charged particle on the halo is described. As far as we know, this is the first relativistic model describing analytically the magnetized halo of a rotating disk. |
1611.00332 | Xisco Jimenez-Forteza | Xisco Jim\'enez-Forteza, David Keitel, Sascha Husa, Mark Hannam,
Sebastian Khan, Michael P\"urrer | Hierarchical data-driven approach to fitting numerical relativity data
for nonprecessing binary black holes with an application to final spin and
radiated energy | 23 pages, 31 figures, 15 tables; data and example implementations as
supplementary material. Updated to match PRD version | Phys. Rev. D 95, 064024 (2017) | 10.1103/PhysRevD.95.064024 | LIGO-P1600270 | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Numerical relativity is an essential tool in studying the coalescence of
binary black holes (BBHs). It is still computationally prohibitive to cover the
BBH parameter space exhaustively, making phenomenological fitting formulas for
BBH waveforms and final-state properties important for practical applications.
We describe a general hierarchical bottom-up fitting methodology to design and
calibrate fits to numerical relativity simulations for the three-dimensional
parameter space of quasicircular nonprecessing merging BBHs, spanned by mass
ratio and by the individual spin components orthogonal to the orbital plane.
Particular attention is paid to incorporating the extreme-mass-ratio limit and
to the subdominant unequal-spin effects. As an illustration of the method, we
provide two applications, to the final spin and final mass (or equivalently:
radiated energy) of the remnant black hole. Fitting to 427 numerical relativity
simulations, we obtain results broadly consistent with previously published
fits, but improving in overall accuracy and particularly in the approach to
extremal limits and for unequal-spin configurations. We also discuss the
importance of data quality studies when combining simulations from diverse
sources, how detailed error budgets will be necessary for further improvements
of these already highly accurate fits, and how this first detailed study of
unequal-spin effects helps in choosing the most informative parameters for
future numerical relativity runs.
| [
{
"created": "Tue, 1 Nov 2016 18:53:02 GMT",
"version": "v1"
},
{
"created": "Mon, 27 Mar 2017 16:01:06 GMT",
"version": "v2"
}
] | 2017-03-28 | [
[
"Jiménez-Forteza",
"Xisco",
""
],
[
"Keitel",
"David",
""
],
[
"Husa",
"Sascha",
""
],
[
"Hannam",
"Mark",
""
],
[
"Khan",
"Sebastian",
""
],
[
"Pürrer",
"Michael",
""
]
] | Numerical relativity is an essential tool in studying the coalescence of binary black holes (BBHs). It is still computationally prohibitive to cover the BBH parameter space exhaustively, making phenomenological fitting formulas for BBH waveforms and final-state properties important for practical applications. We describe a general hierarchical bottom-up fitting methodology to design and calibrate fits to numerical relativity simulations for the three-dimensional parameter space of quasicircular nonprecessing merging BBHs, spanned by mass ratio and by the individual spin components orthogonal to the orbital plane. Particular attention is paid to incorporating the extreme-mass-ratio limit and to the subdominant unequal-spin effects. As an illustration of the method, we provide two applications, to the final spin and final mass (or equivalently: radiated energy) of the remnant black hole. Fitting to 427 numerical relativity simulations, we obtain results broadly consistent with previously published fits, but improving in overall accuracy and particularly in the approach to extremal limits and for unequal-spin configurations. We also discuss the importance of data quality studies when combining simulations from diverse sources, how detailed error budgets will be necessary for further improvements of these already highly accurate fits, and how this first detailed study of unequal-spin effects helps in choosing the most informative parameters for future numerical relativity runs. |
1509.07954 | Xuefeng Zhang | Xuefeng Zhang and Xinliang An | Naked singularity and black hole formation in self-similar
Einstein-scalar fields with exponential potentials | 24 pages, 6 figures; minor changes, more references added | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Motivated by cosmic censorship in general relativity and string theory, we
extend Christodoulou's celebrated examples of naked singularity formation in
the Einstein-massless scalar field system to include a positive or negative
scalar potential of exponential forms, i.e., $V(\phi)=\pm\exp(2\phi/\kappa)$
with a parameter $\kappa$. Under spherical symmetry and a self-similar ansatz
depending on $\kappa$, we derive a 3-dimensional autonomous system of
first-order ordinary differential equations, which incorporates the equations
for massless scalar fields as a special case. Local behavior of the phase space
is studied analytically with global solutions constructed numerically. Within
the 3-dimensional solution manifold, we observe, for the negative potentials,
naked singularity formation from nonsingular initial data for $\kappa^2<1$.
Meanwhile, transitions between solutions containing naked singularities and
black holes are also identified. However, when the potential is taken positive,
numerical evolutions result in formation of black holes, but not naked
singularities.
| [
{
"created": "Sat, 26 Sep 2015 09:23:28 GMT",
"version": "v1"
},
{
"created": "Thu, 22 Oct 2015 07:00:11 GMT",
"version": "v2"
}
] | 2018-02-06 | [
[
"Zhang",
"Xuefeng",
""
],
[
"An",
"Xinliang",
""
]
] | Motivated by cosmic censorship in general relativity and string theory, we extend Christodoulou's celebrated examples of naked singularity formation in the Einstein-massless scalar field system to include a positive or negative scalar potential of exponential forms, i.e., $V(\phi)=\pm\exp(2\phi/\kappa)$ with a parameter $\kappa$. Under spherical symmetry and a self-similar ansatz depending on $\kappa$, we derive a 3-dimensional autonomous system of first-order ordinary differential equations, which incorporates the equations for massless scalar fields as a special case. Local behavior of the phase space is studied analytically with global solutions constructed numerically. Within the 3-dimensional solution manifold, we observe, for the negative potentials, naked singularity formation from nonsingular initial data for $\kappa^2<1$. Meanwhile, transitions between solutions containing naked singularities and black holes are also identified. However, when the potential is taken positive, numerical evolutions result in formation of black holes, but not naked singularities. |
2304.11843 | Bibhas Majhi Ranjan | Bibhas Ranjan Majhi | Laws of thermodynamic equilibrium through relativistic thermodynamics | Generalisation of the results shown, typos corrected, references
added | null | null | null | gr-qc hep-th physics.flu-dyn | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using Israel-Stewart formalism for the description of thermodynamics of an
arbitrary relativistic fluid we propose generalization of Tolman-Ehrenfest
relation and Klein's law on a general background spacetime. The first relation
is a consequence of thermal equilibrium only of a non-viscous fluid, while the
latter one is reflection of only no-diffusion condition with or without
viscosity. Interestingly, both the relations are obtained independently through
the imposition of respective equilibrium conditions and also can be valid in
presence of particular dissipative processes in the fluid. For a spacetime with
a global timelike Killing vector, these two general relations boil down to
standard forms.
| [
{
"created": "Mon, 24 Apr 2023 06:22:11 GMT",
"version": "v1"
},
{
"created": "Fri, 28 Apr 2023 05:19:39 GMT",
"version": "v2"
}
] | 2023-05-01 | [
[
"Majhi",
"Bibhas Ranjan",
""
]
] | Using Israel-Stewart formalism for the description of thermodynamics of an arbitrary relativistic fluid we propose generalization of Tolman-Ehrenfest relation and Klein's law on a general background spacetime. The first relation is a consequence of thermal equilibrium only of a non-viscous fluid, while the latter one is reflection of only no-diffusion condition with or without viscosity. Interestingly, both the relations are obtained independently through the imposition of respective equilibrium conditions and also can be valid in presence of particular dissipative processes in the fluid. For a spacetime with a global timelike Killing vector, these two general relations boil down to standard forms. |
2211.05817 | Ra\'ul Carballo-Rubio | Ra\'ul Carballo-Rubio, Francesco Di Filippo, Stefano Liberati and Matt
Visser | A connection between regular black holes and horizonless ultracompact
stars | 29 pages with references, 6 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We illustrate that regular black holes and horizonless stars, typically
considered as quite distinct families of black hole mimickers, are intimately
intertwined. We show that any spherically symmetric regular black hole can be
continuously deformed into a horizonless star under the mild conditions of
non-negativity of gravitational energy (Misner--Sharp quasi-local mass), and an
assumed linear relation between the latter and the Arnowitt--Deser--Misner
(ADM) mass. We illustrate this general result by considering the family of
geometries proposed by Hayward as the description of regular black holes, and
we also describe the properties of the corresponding horizonless stars. The
form of the associated effective stress-energy tensor shows that these
horizonless stars can be identified as anisotropic gravastars with a soft
surface and inner/outer light rings. We also construct dynamical geometries
that could describe the evolution of regular black holes towards horizonless
stars, and show that semiclassical physics contains the necessary ingredients
to trigger the early stages of such dynamical evolution.
| [
{
"created": "Thu, 10 Nov 2022 19:20:23 GMT",
"version": "v1"
}
] | 2022-11-14 | [
[
"Carballo-Rubio",
"Raúl",
""
],
[
"Di Filippo",
"Francesco",
""
],
[
"Liberati",
"Stefano",
""
],
[
"Visser",
"Matt",
""
]
] | We illustrate that regular black holes and horizonless stars, typically considered as quite distinct families of black hole mimickers, are intimately intertwined. We show that any spherically symmetric regular black hole can be continuously deformed into a horizonless star under the mild conditions of non-negativity of gravitational energy (Misner--Sharp quasi-local mass), and an assumed linear relation between the latter and the Arnowitt--Deser--Misner (ADM) mass. We illustrate this general result by considering the family of geometries proposed by Hayward as the description of regular black holes, and we also describe the properties of the corresponding horizonless stars. The form of the associated effective stress-energy tensor shows that these horizonless stars can be identified as anisotropic gravastars with a soft surface and inner/outer light rings. We also construct dynamical geometries that could describe the evolution of regular black holes towards horizonless stars, and show that semiclassical physics contains the necessary ingredients to trigger the early stages of such dynamical evolution. |
1810.05513 | Antonino Marciano | Andrea Addazi and Antonino Marciano | Quantum Ekpyrotic mechanism in Fermi-bounce curvaton cosmology | 7 pages, 2 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Within the context of the Fermi-bounce curvaton mechanism, we analyze the
one-loop radiative corrections to the four fermion interaction, generated by
the non-dynamical torsion field in the Einstein-Cartan-Holst-Sciama-Kibble
theory. We show that contributions that arise from the one-loop radiative
corrections modify the energy-momentum tensor, {\it mimicking} an effective
Ekpyrotic fluid contribution. For these reasons, we call this effect {\it
quantum Ekpyrotic} mechanism. This leads to the dynamical washing out of
anisotropic contributions to the energy-momentum tensor, without introducing
any new extra Ekpyrotic fluid. We discuss the stability of the bouncing
mechanism and derive the renormalization group flow of the dimensional coupling
constant $\xi$, checking that any change of its sign takes place towards the
bounce. This enforces the theoretical motivations in favor of the torsion
curvaton bounce cosmology as an alternative candidate to the inflation
paradigm.
| [
{
"created": "Fri, 12 Oct 2018 13:51:05 GMT",
"version": "v1"
}
] | 2018-10-15 | [
[
"Addazi",
"Andrea",
""
],
[
"Marciano",
"Antonino",
""
]
] | Within the context of the Fermi-bounce curvaton mechanism, we analyze the one-loop radiative corrections to the four fermion interaction, generated by the non-dynamical torsion field in the Einstein-Cartan-Holst-Sciama-Kibble theory. We show that contributions that arise from the one-loop radiative corrections modify the energy-momentum tensor, {\it mimicking} an effective Ekpyrotic fluid contribution. For these reasons, we call this effect {\it quantum Ekpyrotic} mechanism. This leads to the dynamical washing out of anisotropic contributions to the energy-momentum tensor, without introducing any new extra Ekpyrotic fluid. We discuss the stability of the bouncing mechanism and derive the renormalization group flow of the dimensional coupling constant $\xi$, checking that any change of its sign takes place towards the bounce. This enforces the theoretical motivations in favor of the torsion curvaton bounce cosmology as an alternative candidate to the inflation paradigm. |
2303.01413 | Vitalii Vertogradov | Vitalii Vertogradov, Dmitriy Kudryavcev | On the temperature of hairy black holes | 14 pages, 4 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The gravitational decoupling method represents an extremely useful tool to
obtain new solutions of the Einstein equations through minimal geometrical
deformations. In this paper, we consider the hairy charged black hole obtained
by the gravitational decoupling and calculate their Hawking temperature in
order to compare it with the case when the hairs are ignored. We have found out
that the hairs, under some conditions of black hole parameters, affect the
Hawking temperature and can increase it. We have also found out that the black
hole temperature, in hairy case, doesn't depend on the electric charge.
| [
{
"created": "Thu, 2 Mar 2023 17:03:07 GMT",
"version": "v1"
}
] | 2023-03-03 | [
[
"Vertogradov",
"Vitalii",
""
],
[
"Kudryavcev",
"Dmitriy",
""
]
] | The gravitational decoupling method represents an extremely useful tool to obtain new solutions of the Einstein equations through minimal geometrical deformations. In this paper, we consider the hairy charged black hole obtained by the gravitational decoupling and calculate their Hawking temperature in order to compare it with the case when the hairs are ignored. We have found out that the hairs, under some conditions of black hole parameters, affect the Hawking temperature and can increase it. We have also found out that the black hole temperature, in hairy case, doesn't depend on the electric charge. |
gr-qc/0509039 | Alejandro Corichi | Alejandro Corichi and Alberto Hauser | Bibliography of Publications related to Classical Self-dual variables
and Loop Quantum Gravity | 46 pages | null | null | null | gr-qc | null | This bibliography attempts to give a comprehensive overview of all the
literature related to what is known as the Ashtekar-Sen connection and the
Rovelli-Smolin loop variables, from which the program currently known as Loop
Quantum Gravity emerged. The original version was compiled by Peter Huebner in
1989, and it has been subsequently updated by Gabriela Gonzalez, Bernd
Bruegmann, Monica Pierri, Troy Schilling, Christopher Beetle, Alejandro Corichi
and Alberto Hauser. The criteria for inclusion in this list are the following:
A paper in the classical theory is included if it deals with connection
variables for gravity. If the paper is in the quantum domain, it is included
when it is related directly with gravity using connection/loop variables, with
mathematical aspects of connections, or when it introduces techniques that
might be useful for the construction of the (loop) quantum theory of gravity.
Information about additional literature, new preprints, and especially
corrections are always welcome.
| [
{
"created": "Mon, 12 Sep 2005 18:49:12 GMT",
"version": "v1"
},
{
"created": "Wed, 21 Sep 2005 15:56:59 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Corichi",
"Alejandro",
""
],
[
"Hauser",
"Alberto",
""
]
] | This bibliography attempts to give a comprehensive overview of all the literature related to what is known as the Ashtekar-Sen connection and the Rovelli-Smolin loop variables, from which the program currently known as Loop Quantum Gravity emerged. The original version was compiled by Peter Huebner in 1989, and it has been subsequently updated by Gabriela Gonzalez, Bernd Bruegmann, Monica Pierri, Troy Schilling, Christopher Beetle, Alejandro Corichi and Alberto Hauser. The criteria for inclusion in this list are the following: A paper in the classical theory is included if it deals with connection variables for gravity. If the paper is in the quantum domain, it is included when it is related directly with gravity using connection/loop variables, with mathematical aspects of connections, or when it introduces techniques that might be useful for the construction of the (loop) quantum theory of gravity. Information about additional literature, new preprints, and especially corrections are always welcome. |
2007.06553 | Umananda Dev Goswami | Jyatsnasree Bora and Umananda Dev Goswami | Radial oscillations and gravitational wave echoes of strange stars for
various equations of state | 15 pages, 13 figures, published version in MNRAS | Monthly Notices of the Royal Astronomical Society 502, 1557-1568
(2021) | 10.1093/mnras/stab050 | null | gr-qc astro-ph.HE astro-ph.SR | http://creativecommons.org/licenses/by/4.0/ | We study the radial oscillations of non-rotating strange stars and their
characteristic echo frequencies for three Equations of state (EoSs), viz., MIT
Bag model EoS, linear EoS and polytropic EoS. The frequencies of radial
oscillations of these compact stars are computed for these EoSs. 22 lowest
radial frequencies for each of these three EoSs have been computed. First, for
each EoS, we have integrated Tolman-Oppenheimer-Volkoff (TOV) equations
numerically to calculate the radial and pressure perturbations of strange
stars. Next, the mass-radius relationships for these stars are obtained using
these three EoSs. Then the radial frequencies of oscillations for these EoSs
are calculated. Further, the characteristic gravitational wave echo frequencies
and the repetition of echo frequencies of strange stars are computed for these
EoSs. Our numerical results show that the radial frequencies and also echo
frequencies vastly depend on the model and on the value of the model parameter.
Our results also show that, the radial frequencies of strange stars are maximum
for polytropic EoS in comparison to MIT Bag model EoS and linear EoS. Moreover,
strange stars with MIT Bag model EoS and linear EoS are found to emit
gravitational wave echoes. Whereas, strange stars with polytropic EoS are not
emitting gravitational wave echoes.
| [
{
"created": "Fri, 10 Jul 2020 11:40:00 GMT",
"version": "v1"
},
{
"created": "Thu, 21 Jan 2021 06:49:21 GMT",
"version": "v2"
},
{
"created": "Tue, 9 Feb 2021 09:58:41 GMT",
"version": "v3"
}
] | 2021-02-10 | [
[
"Bora",
"Jyatsnasree",
""
],
[
"Goswami",
"Umananda Dev",
""
]
] | We study the radial oscillations of non-rotating strange stars and their characteristic echo frequencies for three Equations of state (EoSs), viz., MIT Bag model EoS, linear EoS and polytropic EoS. The frequencies of radial oscillations of these compact stars are computed for these EoSs. 22 lowest radial frequencies for each of these three EoSs have been computed. First, for each EoS, we have integrated Tolman-Oppenheimer-Volkoff (TOV) equations numerically to calculate the radial and pressure perturbations of strange stars. Next, the mass-radius relationships for these stars are obtained using these three EoSs. Then the radial frequencies of oscillations for these EoSs are calculated. Further, the characteristic gravitational wave echo frequencies and the repetition of echo frequencies of strange stars are computed for these EoSs. Our numerical results show that the radial frequencies and also echo frequencies vastly depend on the model and on the value of the model parameter. Our results also show that, the radial frequencies of strange stars are maximum for polytropic EoS in comparison to MIT Bag model EoS and linear EoS. Moreover, strange stars with MIT Bag model EoS and linear EoS are found to emit gravitational wave echoes. Whereas, strange stars with polytropic EoS are not emitting gravitational wave echoes. |
gr-qc/0605063 | Marcelo S. Berman | Marcelo Samuel Berman | On the Zero-energy Universe | 14 pages, to be published by International Journal of Theoretical
Physics | Int.J.Theor. Phys.48:3278,2009 | 10.1007/s10773-009-0125-8 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the energy of the Universe, from the pseudo-tensor point of
view(Berman,1981). We find zero values, when the calculations are well-done.The
doubts concerning this subject are clarified, with the novel idea that the
justification for the calculation lies in the association of the equivalence
principle, with the nature of co-motional observers, as demanded in Cosmology.
In Section 4, we give a novel calculation for the zero-total energy result.
| [
{
"created": "Thu, 11 May 2006 03:14:37 GMT",
"version": "v1"
},
{
"created": "Sun, 25 Jun 2006 00:36:10 GMT",
"version": "v2"
},
{
"created": "Sun, 16 Aug 2009 13:39:51 GMT",
"version": "v3"
}
] | 2010-12-20 | [
[
"Berman",
"Marcelo Samuel",
""
]
] | We consider the energy of the Universe, from the pseudo-tensor point of view(Berman,1981). We find zero values, when the calculations are well-done.The doubts concerning this subject are clarified, with the novel idea that the justification for the calculation lies in the association of the equivalence principle, with the nature of co-motional observers, as demanded in Cosmology. In Section 4, we give a novel calculation for the zero-total energy result. |
gr-qc/0401056 | Alexander E. Shalyt-Margolin | A.E.Shalyt-Margolin | Some Implications of the Density Matrix Deformation in Statistical
Mechanics of the Early Universe | 11 pages, no figures | null | null | null | gr-qc | null | This work is an extension of the study into statistical mechanics of the
early Universe that has been the subject in prior works of the author, the
principal approach being the density matrix deformation. In the work it is
demonstrated that the previously derived exponential ansatz may be successfully
applied to the derivation of the free and average energy deformation as well as
entropy deformation. Based on the exponential ansatz, the derivation of a
statistical-mechanical Liouville equation as a deformation of the
quantum-mechanical counterpart is presented. It is shown that deformed
Liouville equation will possess nontrivial components as compared to the normal
equation in two cases: for the original singularity (i.e. early Universe) and
for black hole, that is in complete agreement with the results obtained by the
author with coworkers in earlier works devoted to the deformation in quantum
mechanics at Planck scale. In conclusion some possible applications of the
proposed methods are given, specifically for investigation into thermodynamics
of black holes.
| [
{
"created": "Tue, 13 Jan 2004 14:45:33 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Shalyt-Margolin",
"A. E.",
""
]
] | This work is an extension of the study into statistical mechanics of the early Universe that has been the subject in prior works of the author, the principal approach being the density matrix deformation. In the work it is demonstrated that the previously derived exponential ansatz may be successfully applied to the derivation of the free and average energy deformation as well as entropy deformation. Based on the exponential ansatz, the derivation of a statistical-mechanical Liouville equation as a deformation of the quantum-mechanical counterpart is presented. It is shown that deformed Liouville equation will possess nontrivial components as compared to the normal equation in two cases: for the original singularity (i.e. early Universe) and for black hole, that is in complete agreement with the results obtained by the author with coworkers in earlier works devoted to the deformation in quantum mechanics at Planck scale. In conclusion some possible applications of the proposed methods are given, specifically for investigation into thermodynamics of black holes. |
0708.1747 | Valeria Kagramanova | Valeria Kagramanova, Jutta Kunz and Claus Laemmerzahl | Orbits in the Field of a Gravitating Magnetic Monopole | 24 pages, 15 figures. Accepted for publication in GRG | Gen.Rel.Grav.40:1249-1278,2008 | 10.1007/s10714-007-0602-4 | null | gr-qc | null | Orbits of test particles and light rays are an important tool to study the
properties of space-time metrics. Here we systematically study the properties
of the gravitational field of a globally regular magnetic monopole in terms of
the geodesics of test particles and light. The gravitational field depends on
two dimensionless parameters, defined as ratios of the characteristic mass
scales present. For critical values of these parameters the resulting metric
coefficients develop a singular behavior, which has profound influence on the
properties of the resulting space-time and which is clearly reflected in the
orbits of the test particles and light rays.
| [
{
"created": "Mon, 13 Aug 2007 19:38:45 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Kagramanova",
"Valeria",
""
],
[
"Kunz",
"Jutta",
""
],
[
"Laemmerzahl",
"Claus",
""
]
] | Orbits of test particles and light rays are an important tool to study the properties of space-time metrics. Here we systematically study the properties of the gravitational field of a globally regular magnetic monopole in terms of the geodesics of test particles and light. The gravitational field depends on two dimensionless parameters, defined as ratios of the characteristic mass scales present. For critical values of these parameters the resulting metric coefficients develop a singular behavior, which has profound influence on the properties of the resulting space-time and which is clearly reflected in the orbits of the test particles and light rays. |
1109.4688 | Hanno Sahlmann | Tim Koslowski and Hanno Sahlmann | Loop Quantum Gravity Vacuum with Nondegenerate Geometry | null | SIGMA 8 (2012), 026, 15 pages | 10.3842/SIGMA.2012.026 | APCTP Pre2011-012 | gr-qc math-ph math.MP | http://creativecommons.org/licenses/by-nc-sa/3.0/ | In loop quantum gravity, states of the gravitational field turn out to be
excitations over a vacuum state that is sharply peaked on a degenerate spatial
geometry. While this vacuum is singled out as fundamental due to its invariance
properties, it is also important to consider states that describe
non-degenerate geometries. Such states have features of Bose condensate ground
states. We discuss their construction for the Lie algebra as well as the Weyl
algebra setting, and point out possible applications in effective field theory,
Loop Quantum Cosmology, as well as further generalizations.
| [
{
"created": "Thu, 22 Sep 2011 02:08:29 GMT",
"version": "v1"
},
{
"created": "Sat, 12 May 2012 06:12:12 GMT",
"version": "v2"
}
] | 2012-05-15 | [
[
"Koslowski",
"Tim",
""
],
[
"Sahlmann",
"Hanno",
""
]
] | In loop quantum gravity, states of the gravitational field turn out to be excitations over a vacuum state that is sharply peaked on a degenerate spatial geometry. While this vacuum is singled out as fundamental due to its invariance properties, it is also important to consider states that describe non-degenerate geometries. Such states have features of Bose condensate ground states. We discuss their construction for the Lie algebra as well as the Weyl algebra setting, and point out possible applications in effective field theory, Loop Quantum Cosmology, as well as further generalizations. |
gr-qc/0103098 | Anjan Ananda Sen | A.A.Sen and S.Sen | Cosmology in scalar tensor theory and asymptotically de-Sitter Universe | 7 pages, Revtex Style, 6 Postscript figures | Mod.Phys.Lett.A16:1303-1314,2001 | 10.1142/S021773230100442X | MRI-P-010303 | gr-qc | null | We have investigated the cosmological scenarios with a four dimensional
effective action which is connected with multidimensional, supergravity and
string theories. The solution for the scale factor is such that initially
universe undergoes a decelerated expansion but in late times it enters into the
accelerated expansion phase. Infact, it asymptotically becomes a de-Sitter
universe. The dilaton field in our model is a decreasing function of time and
it becomes a constant in late time resulting the exit from the scalar tensor
theory to the standard Einstein's gravity. Also the dilaton field results the
existence of a positive cosmological constant in late times.
| [
{
"created": "Tue, 27 Mar 2001 17:09:39 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"Sen",
"A. A.",
""
],
[
"Sen",
"S.",
""
]
] | We have investigated the cosmological scenarios with a four dimensional effective action which is connected with multidimensional, supergravity and string theories. The solution for the scale factor is such that initially universe undergoes a decelerated expansion but in late times it enters into the accelerated expansion phase. Infact, it asymptotically becomes a de-Sitter universe. The dilaton field in our model is a decreasing function of time and it becomes a constant in late time resulting the exit from the scalar tensor theory to the standard Einstein's gravity. Also the dilaton field results the existence of a positive cosmological constant in late times. |
1903.00918 | Shabbir Ghulam | Ghulam Shabbir, Fiaz Hussain, A. H. Kara, Muhammad Ramzan | A note on some perfect fluid Kantowski-Sachs and Bianchi type III
space-times and their conformal vector fields in f(R) theory of gravity | 12 pages | Modern Physics Letters A in 2019 | 10.1142/S0217732319500792 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The purpose of this paper is to find conformal vector fields of some perfect
fluid Kantowski-Sachs and Bianchi type III space-times in the f(R) theory of
gravity using direct integration technique. In this study there exists only
eight cases. Studying each case in detail, we found that in two cases proper
conformal vector fields exist while in the rest of six cases conformal vector
fields become Killing vector fields. The dimension of conformal vector fields
is either 4 or 6.
| [
{
"created": "Sun, 3 Mar 2019 14:34:24 GMT",
"version": "v1"
}
] | 2019-04-17 | [
[
"Shabbir",
"Ghulam",
""
],
[
"Hussain",
"Fiaz",
""
],
[
"Kara",
"A. H.",
""
],
[
"Ramzan",
"Muhammad",
""
]
] | The purpose of this paper is to find conformal vector fields of some perfect fluid Kantowski-Sachs and Bianchi type III space-times in the f(R) theory of gravity using direct integration technique. In this study there exists only eight cases. Studying each case in detail, we found that in two cases proper conformal vector fields exist while in the rest of six cases conformal vector fields become Killing vector fields. The dimension of conformal vector fields is either 4 or 6. |
2202.09833 | Leonardo Garc\'ia-Heveling | Leonardo Garc\'ia-Heveling | Topology change with Morse functions: progress on the Borde-Sorkin
conjecture | Small changes in v3: typos fixed, added reference to Yodzis in
introduction. To appear in Adv. Theor. Math. Phys. 23 pages, 8 figures | Advances in Theoretical and Mathematical Physics, Vol. 27, No. 4
(2023), pp. 1159-1190 | 10.4310/ATMP.2023.v27.n4.a4 | null | gr-qc hep-th math-ph math.DG math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Topology change is considered to be a necessary feature of quantum gravity by
some authors, and impossible by others. One of the main arguments against it is
that spacetimes with changing spatial topology have bad causal properties.
Borde and Sorkin proposed a way to avoid this dilemma by considering topology
changing spacetimes constructed from Morse functions, where the metric is
allowed to vanish at isolated points. They conjectured that these Morse
spacetimes are causally continuous (hence quite well behaved), as long as the
index of the Morse points is different from $1$ and $n-1$. In this paper, we
prove a special case of this conjecture. We also argue, heuristically, that the
original conjecture is actually false, and formulate a refined version of it.
| [
{
"created": "Sun, 20 Feb 2022 15:19:36 GMT",
"version": "v1"
},
{
"created": "Mon, 16 May 2022 11:55:10 GMT",
"version": "v2"
},
{
"created": "Tue, 20 Dec 2022 14:31:32 GMT",
"version": "v3"
},
{
"created": "Tue, 13 Feb 2024 08:26:10 GMT",
"version": "v4"
}
] | 2024-06-13 | [
[
"García-Heveling",
"Leonardo",
""
]
] | Topology change is considered to be a necessary feature of quantum gravity by some authors, and impossible by others. One of the main arguments against it is that spacetimes with changing spatial topology have bad causal properties. Borde and Sorkin proposed a way to avoid this dilemma by considering topology changing spacetimes constructed from Morse functions, where the metric is allowed to vanish at isolated points. They conjectured that these Morse spacetimes are causally continuous (hence quite well behaved), as long as the index of the Morse points is different from $1$ and $n-1$. In this paper, we prove a special case of this conjecture. We also argue, heuristically, that the original conjecture is actually false, and formulate a refined version of it. |
gr-qc/0601047 | Z. Y. Turakulov | Z. Ya. Turakulov, A. T. Muminov | Electromagnetic field with constraints and Papapetrou equation | 11 pages, PDF file | null | 10.1515/zna-2006-3-407 | null | gr-qc | null | It is shown that geometric optical description of electromagnetic wave with
account of its polarization in curved space-time can be obtained
straightforwardly from the classical variational principle for electromagnetic
field. For this end the entire functional space of electromagnetic fields must
be reduced to its subspace of locally plane monochromatic waves. We have
formulated the constraints under which the entire functional space of
electromagnetic fields reduces to its subspace of locally plane monochromatic
waves. These constraints introduce variables of another kind which specify a
field of local frames associated to the wave and contain some congruence of
null-curves. The Lagrangian for constrained electromagnetic field contains
variables of two kinds, namely, a congruence of null-curves and the field
itself. This yields two kinds of Euler-Lagrange equations. Equations of first
kind are trivial due to the constraints imposed. Variation of the curves yields
the Papapetrou equations for a classical massless particle with helicity 1.
| [
{
"created": "Thu, 12 Jan 2006 04:45:51 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Turakulov",
"Z. Ya.",
""
],
[
"Muminov",
"A. T.",
""
]
] | It is shown that geometric optical description of electromagnetic wave with account of its polarization in curved space-time can be obtained straightforwardly from the classical variational principle for electromagnetic field. For this end the entire functional space of electromagnetic fields must be reduced to its subspace of locally plane monochromatic waves. We have formulated the constraints under which the entire functional space of electromagnetic fields reduces to its subspace of locally plane monochromatic waves. These constraints introduce variables of another kind which specify a field of local frames associated to the wave and contain some congruence of null-curves. The Lagrangian for constrained electromagnetic field contains variables of two kinds, namely, a congruence of null-curves and the field itself. This yields two kinds of Euler-Lagrange equations. Equations of first kind are trivial due to the constraints imposed. Variation of the curves yields the Papapetrou equations for a classical massless particle with helicity 1. |
1703.09131 | Henrique de Oliveira | P. C. M. Clemente and H. P. de Oliveira | Puncture black hole initial data: a single domain Galerkin-Collocation
method for trumpet and wormhole data sets | 9 figures | Phys. Rev. D 96, 024035 (2017) | 10.1103/PhysRevD.96.024035 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a single domain Galerkin-Collocation method to calculate puncture
initial data sets for single and binary, either in the trumpet or wormhole
geometries. The combination of aspects belonging to the Galerkin and the
Collocation methods together with the adoption of spherical coordinates in all
cases show to be very effective. We have proposed a unified expression for the
conformal factor to describe trumpet and spinning black holes. In particular,
for the spinning trumpet black holes, we have exhibited the deformation of the
limit surface due to the spin from a sphere to an oblate spheroid. We have also
revisited the energy content in the trumpet and wormhole puncture data sets.
The algorithm can be extended to describe binary black holes.
| [
{
"created": "Mon, 27 Mar 2017 15:03:48 GMT",
"version": "v1"
}
] | 2017-08-02 | [
[
"Clemente",
"P. C. M.",
""
],
[
"de Oliveira",
"H. P.",
""
]
] | We present a single domain Galerkin-Collocation method to calculate puncture initial data sets for single and binary, either in the trumpet or wormhole geometries. The combination of aspects belonging to the Galerkin and the Collocation methods together with the adoption of spherical coordinates in all cases show to be very effective. We have proposed a unified expression for the conformal factor to describe trumpet and spinning black holes. In particular, for the spinning trumpet black holes, we have exhibited the deformation of the limit surface due to the spin from a sphere to an oblate spheroid. We have also revisited the energy content in the trumpet and wormhole puncture data sets. The algorithm can be extended to describe binary black holes. |
1604.08247 | Elena Kopteva | Maria Korkina, Elena Kopteva | The mass function method for obtaining exact solutions of Einstein
equations | null | Space, Time and Fundamental Interactions. 2012. V. 1, p. 38 - 47 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that the mass function method makes it much easier to obtain the
exact solutions of Einstein equations. The known solutions for empty space and
for the universe filled with dust-like matter are considered from the point of
view of the method and new exact solutions are obtained. Generalized solutions
for the Schwarzschild type black holes are considered. It is shown that such
black holes always contain non-baryonic matter. New exact solution for the
black hole embedded into dust matter cosmological background is obtained.
| [
{
"created": "Wed, 27 Apr 2016 21:12:00 GMT",
"version": "v1"
},
{
"created": "Fri, 29 Apr 2016 09:16:10 GMT",
"version": "v2"
}
] | 2016-05-02 | [
[
"Korkina",
"Maria",
""
],
[
"Kopteva",
"Elena",
""
]
] | We show that the mass function method makes it much easier to obtain the exact solutions of Einstein equations. The known solutions for empty space and for the universe filled with dust-like matter are considered from the point of view of the method and new exact solutions are obtained. Generalized solutions for the Schwarzschild type black holes are considered. It is shown that such black holes always contain non-baryonic matter. New exact solution for the black hole embedded into dust matter cosmological background is obtained. |
2309.13140 | Emilio Rub\'in de Celis | E. Rub\'in de Celis and C. Simeone | Tides across thin-shells: differences between spacetimes with one and
two asymptotic regions | 13 pages. No figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Traversability across thin shells is investigated, with special attention
devoted to the difference in tides related with different global properties of
the geometries. While we have recently associated curvature jumps across
infinitely thin shells to troublesome tides and consequent very restrictive
conditions for a safe travel across a throat satisfying the flare-out condition
in spacetimes with two asymptotic regions, now we find that analogous problems
can be significantly reduced or even cancelled across shells joining an inner
with an outer submanifold of spacetimes with one asymptotic region. We also
show that, within this framework, cylindrical shells present an advantage over
spherical shells.
| [
{
"created": "Fri, 22 Sep 2023 18:50:20 GMT",
"version": "v1"
}
] | 2023-09-26 | [
[
"de Celis",
"E. Rubín",
""
],
[
"Simeone",
"C.",
""
]
] | Traversability across thin shells is investigated, with special attention devoted to the difference in tides related with different global properties of the geometries. While we have recently associated curvature jumps across infinitely thin shells to troublesome tides and consequent very restrictive conditions for a safe travel across a throat satisfying the flare-out condition in spacetimes with two asymptotic regions, now we find that analogous problems can be significantly reduced or even cancelled across shells joining an inner with an outer submanifold of spacetimes with one asymptotic region. We also show that, within this framework, cylindrical shells present an advantage over spherical shells. |
2301.02847 | Haomin Rao | Mingzhe Li and Haomin Rao | Irregular universe in the Nieh-Yan modified teleparallel gravity | 20 pages, 1 figures, irregular universe, teleparallel gravity | null | 10.1016/j.physletb.2023.137929 | USTC-ICTS/PCFT-22-27 | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by/4.0/ | The Nieh-Yan modified teleparallel gravity is a model which modifies the
general relativity equivalent teleparallel gravity by a coupling between the
Nieh-Yan density and an axion-like field. This model predicts parity violations
in the gravitational waves if the axion-like field has a non-trivial
background, and more importantly it is ghost free and avoids the pathologies
presented in other parity-violating gravity models. The cosmological dynamics
and perturbations of the Nieh-Yan modified teleparallel gravity have been
investigated in detail, but all these previous investigations rely on the
symmetry requirement that in the background universe both the metric and affine
connection are homogeneous and isotropic. In this paper we relax the symmetry
constraint on the connection and leave it arbitrary at the beginning, after all
the cosmological principle only needs the metric of the background spacetime to
meet the symmetry requirement. We find a new flat universe solution for the
Nieh-Yan modified teleparallel gravity, for which the background dynamics
itself is unchanged but the perturbations around it present a new feature that
the scalar and tensor perturbations are coupled together at the linear level.
The implications of this peculiar feature in primordial perturbations from
inflation are also discussed.
| [
{
"created": "Sat, 7 Jan 2023 13:20:56 GMT",
"version": "v1"
},
{
"created": "Thu, 20 Apr 2023 01:49:40 GMT",
"version": "v2"
}
] | 2023-05-17 | [
[
"Li",
"Mingzhe",
""
],
[
"Rao",
"Haomin",
""
]
] | The Nieh-Yan modified teleparallel gravity is a model which modifies the general relativity equivalent teleparallel gravity by a coupling between the Nieh-Yan density and an axion-like field. This model predicts parity violations in the gravitational waves if the axion-like field has a non-trivial background, and more importantly it is ghost free and avoids the pathologies presented in other parity-violating gravity models. The cosmological dynamics and perturbations of the Nieh-Yan modified teleparallel gravity have been investigated in detail, but all these previous investigations rely on the symmetry requirement that in the background universe both the metric and affine connection are homogeneous and isotropic. In this paper we relax the symmetry constraint on the connection and leave it arbitrary at the beginning, after all the cosmological principle only needs the metric of the background spacetime to meet the symmetry requirement. We find a new flat universe solution for the Nieh-Yan modified teleparallel gravity, for which the background dynamics itself is unchanged but the perturbations around it present a new feature that the scalar and tensor perturbations are coupled together at the linear level. The implications of this peculiar feature in primordial perturbations from inflation are also discussed. |
1210.1402 | Harvey S. Reall | Harvey S. Reall | Higher dimensional black holes | Contribution to the proceedings of "Relativity and Gravitation - 100
years after Einstein in Prague" (Prague, June 2012) and the 13th Marcel
Grossmann Meeting (Stockholm, July 2012). v2: references added | null | 10.1142/S0218271812300017 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This article reviews black hole solutions of higher-dimensional General
Relativity. The focus is on stationary vacuum solutions and recent work on
instabilities of such solutions.
| [
{
"created": "Thu, 4 Oct 2012 12:03:48 GMT",
"version": "v1"
},
{
"created": "Fri, 12 Oct 2012 08:52:00 GMT",
"version": "v2"
}
] | 2015-06-11 | [
[
"Reall",
"Harvey S.",
""
]
] | This article reviews black hole solutions of higher-dimensional General Relativity. The focus is on stationary vacuum solutions and recent work on instabilities of such solutions. |
gr-qc/9312013 | Joakim Hallin | J. Hallin | Representations of the $SU(N)$ $T$-algebra and the loop representation
in $1+1$-dimensions | 15 pages, LaTeX, 1 postscript figure included, uses epsf.sty,
G\"oteborg ITP 93-39 | Class.Quant.Grav.11:1615-1630,1994 | 10.1088/0264-9381/11/7/005 | null | gr-qc | null | We consider the phase-space of Yang-Mills on a cylindrical space-time ($S^1
\times {\bf R}$) and the associated algebra of gauge-invariant functions, the
$T$-variables. We solve the Mandelstam identities both classically and
quantum-mechanically by considering the $T$-variables as functions of the
eigenvalues of the holonomy and their associated momenta. It is shown that
there are two inequivalent representations of the quantum $T$-algebra. Then we
compare this reduced phase space approach to Dirac quantization and find it to
give essentially equivalent results. We proceed to define a loop representation
in each of these two cases. One of these loop representations (for $N=2$) is
more or less equivalent to the usual loop representation.
| [
{
"created": "Tue, 7 Dec 1993 14:50:59 GMT",
"version": "v1"
}
] | 2010-04-06 | [
[
"Hallin",
"J.",
""
]
] | We consider the phase-space of Yang-Mills on a cylindrical space-time ($S^1 \times {\bf R}$) and the associated algebra of gauge-invariant functions, the $T$-variables. We solve the Mandelstam identities both classically and quantum-mechanically by considering the $T$-variables as functions of the eigenvalues of the holonomy and their associated momenta. It is shown that there are two inequivalent representations of the quantum $T$-algebra. Then we compare this reduced phase space approach to Dirac quantization and find it to give essentially equivalent results. We proceed to define a loop representation in each of these two cases. One of these loop representations (for $N=2$) is more or less equivalent to the usual loop representation. |
1005.4480 | Muhammad Sharif | M. Sharif and M. Zubair | Dynamics of Bianchi I Universe with Magnetized Anisotropic Dark Energy | 16 pages, 2 figures, accepted for publication in Astrophys. Space Sci | Astrophys.Space Sci.330:399-405,2010 | 10.1007/s10509-010-0414-y | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study Bianchi type $I$ cosmological model in the presence of magnetized
anisotropic dark energy. The energy-momentum tensor consists of anisotropic
fluid with anisotropic EoS $p=\omega{\rho}$ and a uniform magnetic field of
energy density $\rho_B$. We obtain exact solutions to the field equations using
the condition that expansion is proportional to the shear scalar. The physical
behavior of the model is discussed with and without magnetic field. We conclude
that universe model as well as anisotropic fluid do not approach isotropy
through the evolution of the universe.
| [
{
"created": "Tue, 25 May 2010 04:28:12 GMT",
"version": "v1"
}
] | 2010-11-03 | [
[
"Sharif",
"M.",
""
],
[
"Zubair",
"M.",
""
]
] | We study Bianchi type $I$ cosmological model in the presence of magnetized anisotropic dark energy. The energy-momentum tensor consists of anisotropic fluid with anisotropic EoS $p=\omega{\rho}$ and a uniform magnetic field of energy density $\rho_B$. We obtain exact solutions to the field equations using the condition that expansion is proportional to the shear scalar. The physical behavior of the model is discussed with and without magnetic field. We conclude that universe model as well as anisotropic fluid do not approach isotropy through the evolution of the universe. |
gr-qc/0201070 | Jonathan Halliwell | J.J.Halliwell and J.Thorwart | Life in an Energy Eigenstate: Decoherent Histories Analysis of a Model
Timeless Universe | 57 pages, plain Tex, 1 figure | Phys.Rev. D65 (2002) 104009 | 10.1103/PhysRevD.65.104009 | IC/TP/1-02/13 | gr-qc | null | Inspired by quantum cosmology, in which the wave function of the universe is
annihilated by the total Hamiltonian, we consider the internal dynamics of a
simple particle system in an energy eigenstate. Such a system does not possess
a uniquely defined time parameter and all physical questions about it must be
posed without reference to time. We consider in particular the question, what
is the probability that the system's trajectory passes through a set of regions
of configuration space without reference to time? We first consider the
classical case, where the answer has a variety of forms in terms of a phase
space probability distribution function. We then consider the quantum case, and
we analyze this question using the decoherent histories approach to quantum
theory, adapted to questions which do not involve time. When the histories are
decoherent, the probabilities approximately coincide with the classical case,
with the phase space probability distribution replaced by the Wigner function
of the quantum state. For some initial states, decoherence requires an
environment, and we compute the required influence functional and examine some
of its properties. Special attention is given to the inner product used in the
construction (the induced or Rieffel inner product), the construction of class
operators describing the histories, and the extent to which reparametrization
invariance is respected. Our results indicate that simple systems without an
explicit time parameter may be quantized using the decoherent histories
approach, and the expected classical limit extracted. The results support, for
simple models, the usual heuristic proposals for the probability distribution
function associated with a semiclassical wave function satisfying the
Wheeler-DeWitt equation.
| [
{
"created": "Mon, 21 Jan 2002 18:02:12 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Halliwell",
"J. J.",
""
],
[
"Thorwart",
"J.",
""
]
] | Inspired by quantum cosmology, in which the wave function of the universe is annihilated by the total Hamiltonian, we consider the internal dynamics of a simple particle system in an energy eigenstate. Such a system does not possess a uniquely defined time parameter and all physical questions about it must be posed without reference to time. We consider in particular the question, what is the probability that the system's trajectory passes through a set of regions of configuration space without reference to time? We first consider the classical case, where the answer has a variety of forms in terms of a phase space probability distribution function. We then consider the quantum case, and we analyze this question using the decoherent histories approach to quantum theory, adapted to questions which do not involve time. When the histories are decoherent, the probabilities approximately coincide with the classical case, with the phase space probability distribution replaced by the Wigner function of the quantum state. For some initial states, decoherence requires an environment, and we compute the required influence functional and examine some of its properties. Special attention is given to the inner product used in the construction (the induced or Rieffel inner product), the construction of class operators describing the histories, and the extent to which reparametrization invariance is respected. Our results indicate that simple systems without an explicit time parameter may be quantized using the decoherent histories approach, and the expected classical limit extracted. The results support, for simple models, the usual heuristic proposals for the probability distribution function associated with a semiclassical wave function satisfying the Wheeler-DeWitt equation. |
1711.00855 | Peter Zimmerman | Samuel E. Gralla and Peter Zimmerman | Critical Exponents of Extremal Kerr Perturbations | 21 pages. v2 updated to match published version | Classical and Quantum Gravity, Volume 35 (2018), Number 9 | 10.1088/1361-6382/aab140 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that scalar, electromagnetic, and gravitational perturbations of
extremal Kerr black holes are asymptotically self-similar under the
near-horizon, late-time scaling symmetry of the background metric. This
accounts for the Aretakis instability (growth of transverse derivatives) as a
critical phenomenon associated with the emergent symmetry. We compute the
critical exponent of each mode, which is equivalent to its decay rate. It
follows from symmetry arguments that, despite the growth of transverse
derivatives, all generally covariant scalar quantities decay to zero.
| [
{
"created": "Thu, 2 Nov 2017 18:00:00 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Nov 2017 20:45:21 GMT",
"version": "v2"
},
{
"created": "Mon, 2 Apr 2018 00:05:51 GMT",
"version": "v3"
}
] | 2018-04-03 | [
[
"Gralla",
"Samuel E.",
""
],
[
"Zimmerman",
"Peter",
""
]
] | We show that scalar, electromagnetic, and gravitational perturbations of extremal Kerr black holes are asymptotically self-similar under the near-horizon, late-time scaling symmetry of the background metric. This accounts for the Aretakis instability (growth of transverse derivatives) as a critical phenomenon associated with the emergent symmetry. We compute the critical exponent of each mode, which is equivalent to its decay rate. It follows from symmetry arguments that, despite the growth of transverse derivatives, all generally covariant scalar quantities decay to zero. |
gr-qc/0310024 | Felix Finster | Felix Finster, Niky Kamran, Joel Smoller, and Shing-Tung Yau | An Integral Spectral Representation of the Propagator for the Wave
Equation in the Kerr Geometry | 41 pages, 4 figures, minor corrections | Commun.Math.Phys. 260 (2005) 257-298 | 10.1007/s00220-005-1390-x | null | gr-qc astro-ph math-ph math.MP | null | We consider the scalar wave equation in the Kerr geometry for Cauchy data
which is smooth and compactly supported outside the event horizon. We derive an
integral representation which expresses the solution as a superposition of
solutions of the radial and angular ODEs which arise in the separation of
variables. In particular, we prove completeness of the solutions of the
separated ODEs.
This integral representation is a suitable starting point for a detailed
analysis of the long-time dynamics of scalar waves in the Kerr geometry.
| [
{
"created": "Sat, 4 Oct 2003 22:52:51 GMT",
"version": "v1"
},
{
"created": "Fri, 23 Jul 2004 09:44:11 GMT",
"version": "v2"
},
{
"created": "Tue, 12 Apr 2005 17:53:12 GMT",
"version": "v3"
},
{
"created": "Wed, 6 Jul 2005 16:21:51 GMT",
"version": "v4"
},
{
"created": "Thu, 6 Mar 2008 20:20:13 GMT",
"version": "v5"
}
] | 2009-11-10 | [
[
"Finster",
"Felix",
""
],
[
"Kamran",
"Niky",
""
],
[
"Smoller",
"Joel",
""
],
[
"Yau",
"Shing-Tung",
""
]
] | We consider the scalar wave equation in the Kerr geometry for Cauchy data which is smooth and compactly supported outside the event horizon. We derive an integral representation which expresses the solution as a superposition of solutions of the radial and angular ODEs which arise in the separation of variables. In particular, we prove completeness of the solutions of the separated ODEs. This integral representation is a suitable starting point for a detailed analysis of the long-time dynamics of scalar waves in the Kerr geometry. |
gr-qc/0404096 | Innocenzo M. Pinto | R. P. Croce, Th. Demma, M. Longo, S. Marano, V. Matta, V. Pierro, and
I. M. Pinto | How Many Templates for GW Chirp Detection? The Minimal-Match Issue
Revisited | submitted to Class. Quantum Grav. Typing error in eq. (4.8) fixed;
figure replaced in version 2 | Class.Quant.Grav. 21 (2004) 4955-4962 | 10.1088/0264-9381/21/21/013 | null | gr-qc | null | In a recent paper dealing with maximum likelihood detection of gravitational
wave chirps from coalescing binaries with unknown parameters we introduced an
accurate representation of the no-signal cumulative distribution of the
supremum of the whole correlator bank. This result can be used to derive a
refined estimate of the number of templates yielding the best tradeoff between
detector's performance (in terms of lost signals among those potentially
detectable) and computational burden.
| [
{
"created": "Wed, 21 Apr 2004 18:59:32 GMT",
"version": "v1"
},
{
"created": "Sat, 24 Apr 2004 18:51:48 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Croce",
"R. P.",
""
],
[
"Demma",
"Th.",
""
],
[
"Longo",
"M.",
""
],
[
"Marano",
"S.",
""
],
[
"Matta",
"V.",
""
],
[
"Pierro",
"V.",
""
],
[
"Pinto",
"I. M.",
""
]
] | In a recent paper dealing with maximum likelihood detection of gravitational wave chirps from coalescing binaries with unknown parameters we introduced an accurate representation of the no-signal cumulative distribution of the supremum of the whole correlator bank. This result can be used to derive a refined estimate of the number of templates yielding the best tradeoff between detector's performance (in terms of lost signals among those potentially detectable) and computational burden. |
1409.2101 | Gary Osborn | Gary Osborn | A low order extension the Lienard-Wiechert retardation equations to
include the Thomas precession | Equation 21 was extended to the third derivative in this version | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In a calculation that directly parallels the derivation of the Thomas
precession, the first time derivative of the retarded potentials is derived.
The solutions have to be integrated in time to obtain the potential solution.
The Thomas precession vanishes when the acceleration and velocity vectors are
parallel, causing the solution for the dipole antenna to be the same as for the
Lienard-Wiechert solution, and those solutions are in turn always solutions to
the Maxwell equations. The solution for the current loop antenna is not a
solution to the Maxwell equations. Field equations are obtained by
restructuring the Proca equations that are commensurate with the low order
retardation solutions. The solutions are not in the Lorentz gauge and they are
not solutions to the unmodified Proca equations. The high order terms are not
solutions to the equations. In representing angular relationships, an argument
is developed that derivatives beyond the first will be required for more
complete solutions. The calculations are not in tensor form, but the tensors
represent angular relationships, and the inference is based on the tensor
irreducibility theorem. In being linear equations expressing angular
relationships, the theorem implies that exact retardation equations do not
exist unless the contravariant tensor of rank n+1 is reducible.
| [
{
"created": "Sun, 7 Sep 2014 09:59:51 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Sep 2014 05:05:02 GMT",
"version": "v2"
}
] | 2014-09-19 | [
[
"Osborn",
"Gary",
""
]
] | In a calculation that directly parallels the derivation of the Thomas precession, the first time derivative of the retarded potentials is derived. The solutions have to be integrated in time to obtain the potential solution. The Thomas precession vanishes when the acceleration and velocity vectors are parallel, causing the solution for the dipole antenna to be the same as for the Lienard-Wiechert solution, and those solutions are in turn always solutions to the Maxwell equations. The solution for the current loop antenna is not a solution to the Maxwell equations. Field equations are obtained by restructuring the Proca equations that are commensurate with the low order retardation solutions. The solutions are not in the Lorentz gauge and they are not solutions to the unmodified Proca equations. The high order terms are not solutions to the equations. In representing angular relationships, an argument is developed that derivatives beyond the first will be required for more complete solutions. The calculations are not in tensor form, but the tensors represent angular relationships, and the inference is based on the tensor irreducibility theorem. In being linear equations expressing angular relationships, the theorem implies that exact retardation equations do not exist unless the contravariant tensor of rank n+1 is reducible. |
1804.03003 | Yun Soo Myung | Yun Soo Myung, De-cheng Zou | Correlated stability conjecture for AdS black holes in higher
dimensional Ricci cubic gravity | 25 pages, 4 figures, version to appear in GRG | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the correlated stability conjecture for AdS black holes
obtained from the higher dimensional Ricci cubic gravity. It shows that the
Ricci tensor perturbations exhibit unstable modes for small AdS black holes
when solving Lichnerowicz equation, leading to Gregory-Laflamme instability. On
the other hand, we find that a small black hole is thermodynamically unstable
by showing the negative heat capacity. This suggests that the correlated
stability conjecture holds for AdS black holes in Ricci cubic gravity.
Furthermore, we find a newly non-AdS black hole by solving static Lichnerowicz
equations, confirming the threshold mass for Gregory-Laflamme instability.
| [
{
"created": "Fri, 6 Apr 2018 04:59:10 GMT",
"version": "v1"
},
{
"created": "Mon, 26 Jun 2023 22:54:45 GMT",
"version": "v2"
}
] | 2023-06-28 | [
[
"Myung",
"Yun Soo",
""
],
[
"Zou",
"De-cheng",
""
]
] | We investigate the correlated stability conjecture for AdS black holes obtained from the higher dimensional Ricci cubic gravity. It shows that the Ricci tensor perturbations exhibit unstable modes for small AdS black holes when solving Lichnerowicz equation, leading to Gregory-Laflamme instability. On the other hand, we find that a small black hole is thermodynamically unstable by showing the negative heat capacity. This suggests that the correlated stability conjecture holds for AdS black holes in Ricci cubic gravity. Furthermore, we find a newly non-AdS black hole by solving static Lichnerowicz equations, confirming the threshold mass for Gregory-Laflamme instability. |
gr-qc/9407006 | Christoph Schweigert | K. Peeters, C. Schweigert and J.W. van Holten | Extended Geometry of Black Holes | 9pp. (A4) LaTeX, epsf.sty, 1 figure, appended as a compressed and
uuencoded postscript file, NIKHEF-H/94-03 | Class.Quant.Grav.12:173-180,1995 | 10.1088/0264-9381/12/1/015 | null | gr-qc hep-th | null | We reconsider space-time singularities in classical Einsteinian general
relativity: with the help of several new co-ordinate systems we show that the
Schwarzschild solution can be extended beyond the curvature singularity at r=0.
The extension appears as an infinite covering of standard Kruskal space-time.
While the two-dimensional reduction of this infinite sequence of
Kruskal-Szekeres domains obtained by suppressing the angular degrees of freedom
is still a topological manifold - albeit one for which the metric structure is
singular on one-dimensional submanifolds - we obtain for the full
four-dimensional geometry the more general structure of a stratified variety.
| [
{
"created": "Fri, 8 Jul 1994 10:54:27 GMT",
"version": "v1"
}
] | 2010-04-06 | [
[
"Peeters",
"K.",
""
],
[
"Schweigert",
"C.",
""
],
[
"van Holten",
"J. W.",
""
]
] | We reconsider space-time singularities in classical Einsteinian general relativity: with the help of several new co-ordinate systems we show that the Schwarzschild solution can be extended beyond the curvature singularity at r=0. The extension appears as an infinite covering of standard Kruskal space-time. While the two-dimensional reduction of this infinite sequence of Kruskal-Szekeres domains obtained by suppressing the angular degrees of freedom is still a topological manifold - albeit one for which the metric structure is singular on one-dimensional submanifolds - we obtain for the full four-dimensional geometry the more general structure of a stratified variety. |
1002.2178 | Navin Sivanandam | Navin Sivanandam | A Computational Anthropic Principle: Where is the Hardest Problem in the
Multiverse? | 4th Place in FQXi essay contest: "What is Ultimately Possible in
Physics?" | null | null | UTTG-14-09 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The anthropic principle is an inevitable constraint on the space of possible
theories. As such it is central to determining the limits of physics. In
particular, we contend that what is ultimately possible in physics is
determined by restrictions on the computational capacity of the universe, and
that observers are more likely to be found where more complicated calculations
are possible.
Our discussion covers the inevitability of theoretical bias and how
anthropics and computation can be an aid to imposing these biases on the theory
landscape in a systematic way. Further, we argue for (as far as possible)
top-down rather than bottom-up anthropic measures, contending that that the
latter can often be misleading.
We begin the construction of an explicit computational measure by examining
the effect of the cosmological constant on computational bounds in a given
universe, drawing from previous work on using entropy production as a proxy for
observers by Bousso, Harnik, Kribs and Perez. In addition, we highlight a few
of the additional computational considerations that may be used to extend such
a measure.
| [
{
"created": "Wed, 10 Feb 2010 19:06:58 GMT",
"version": "v1"
}
] | 2010-02-11 | [
[
"Sivanandam",
"Navin",
""
]
] | The anthropic principle is an inevitable constraint on the space of possible theories. As such it is central to determining the limits of physics. In particular, we contend that what is ultimately possible in physics is determined by restrictions on the computational capacity of the universe, and that observers are more likely to be found where more complicated calculations are possible. Our discussion covers the inevitability of theoretical bias and how anthropics and computation can be an aid to imposing these biases on the theory landscape in a systematic way. Further, we argue for (as far as possible) top-down rather than bottom-up anthropic measures, contending that that the latter can often be misleading. We begin the construction of an explicit computational measure by examining the effect of the cosmological constant on computational bounds in a given universe, drawing from previous work on using entropy production as a proxy for observers by Bousso, Harnik, Kribs and Perez. In addition, we highlight a few of the additional computational considerations that may be used to extend such a measure. |
gr-qc/0501061 | James M. Overduin | R. J. Adler and J. M. Overduin | The nearly flat universe | 14 pages, 5 figures | Gen.Rel.Grav.37:1491-1503,2005 | 10.1007/s10714-005-0189-6 | null | gr-qc | null | We study here what it means for the Universe to be nearly flat, as opposed to
exactly flat. We give three definitions of nearly flat, based on density,
geometry and dynamics; all three definitions are equivalent and depend on a
single constant flatness parameter epsilon that quantifies the notion of nearly
flat. Observations can only place an upper limit on epsilon, and always allow
the possibility that the Universe is infinite with k=-1 or finite with k=1. We
use current observational data to obtain a numerical upper limit on the
flatness parameter and discuss its implications, in particular the
"naturalness" of the nearly flat Universe.
| [
{
"created": "Thu, 20 Jan 2005 01:29:22 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Adler",
"R. J.",
""
],
[
"Overduin",
"J. M.",
""
]
] | We study here what it means for the Universe to be nearly flat, as opposed to exactly flat. We give three definitions of nearly flat, based on density, geometry and dynamics; all three definitions are equivalent and depend on a single constant flatness parameter epsilon that quantifies the notion of nearly flat. Observations can only place an upper limit on epsilon, and always allow the possibility that the Universe is infinite with k=-1 or finite with k=1. We use current observational data to obtain a numerical upper limit on the flatness parameter and discuss its implications, in particular the "naturalness" of the nearly flat Universe. |
1311.4888 | Gabor Kunstatter | Gabor Kunstatter and Hideki Maeda | Throat quantization of the Schwarzschild-Tangherlini(-AdS) Black Hole | 39 pages, 3 figures, 2014 Class. Quantum Grav. 31 115009 | Class. Quant. Grav. 31 (2014) 115009 | 10.1088/0264-9381/31/11/115009 | RUP-13-15, CECS-PHY-13/09 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Adopting the throat quantization pioneered by Louko and M\"akel\"a, we derive
the mass and area spectra for the Schwarzschild-Tangherlini black hole and its
anti-de~Sitter (AdS) generalization in arbitrary dimensions. We obtain exact
spectra in three special cases: the three-dimensional BTZ black hole, toroidal
black holes in any dimension, and five-dimensional
Schwarzshild-Tangherlini(-AdS) black holes. For the remaining cases the spectra
are obtained for large mass using the WKB approximation. For asymptotically
flat black holes, the area/entropy has an equally spaced spectrum, as expected
from previous work. In the asymptotically AdS case on the other hand, it is the
mass spectrum that is equally spaced. Our exact results for the BTZ black hole
with Dirichlet and Neumann boundary conditions are consistent with the spacing
of the spectra of the corresponding operators in the dual CFT.
| [
{
"created": "Tue, 19 Nov 2013 21:00:10 GMT",
"version": "v1"
},
{
"created": "Sun, 1 Jun 2014 22:33:40 GMT",
"version": "v2"
}
] | 2017-06-13 | [
[
"Kunstatter",
"Gabor",
""
],
[
"Maeda",
"Hideki",
""
]
] | Adopting the throat quantization pioneered by Louko and M\"akel\"a, we derive the mass and area spectra for the Schwarzschild-Tangherlini black hole and its anti-de~Sitter (AdS) generalization in arbitrary dimensions. We obtain exact spectra in three special cases: the three-dimensional BTZ black hole, toroidal black holes in any dimension, and five-dimensional Schwarzshild-Tangherlini(-AdS) black holes. For the remaining cases the spectra are obtained for large mass using the WKB approximation. For asymptotically flat black holes, the area/entropy has an equally spaced spectrum, as expected from previous work. In the asymptotically AdS case on the other hand, it is the mass spectrum that is equally spaced. Our exact results for the BTZ black hole with Dirichlet and Neumann boundary conditions are consistent with the spacing of the spectra of the corresponding operators in the dual CFT. |
1004.2572 | Ozay Gurtug | O. Unver and O. Gurtug | Quantum singularities in (2+1) dimensional matter coupled black hole
spacetimes | 13 pages, 1 figure. Final version, to appear in PRD | Phys.Rev.D82:084016,2010 | 10.1103/PhysRevD.82.084016 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Quantum singularities considered in the 3D BTZ spacetime by Pitelli and
Letelier (Phys. Rev. D77: 124030, 2008) is extended to charged BTZ and 3D
Einstein-Maxwell-dilaton gravity spacetimes. The occurence of naked
singularities in the Einstein-Maxwell extension of the BTZ spacetime both in
linear and non-linear electrodynamics as well as in the
Einstein-Maxwell-dilaton gravity spacetimes are analysed with the quantum test
fields obeying the Klein-Gordon and Dirac equations. We show that with the
inclusion of the matter fields; the conical geometry near r=0 is removed and
restricted classes of solutions are admitted for the Klein-Gordon and Dirac
equations. Hence, the classical central singularity at r=0 turns out to be
quantum mechanically singular for quantum particles obeying Klein-Gordon
equation but nonsingular for fermions obeying Dirac equation. Explicit
calculations reveal that the occurrence of the timelike naked singularities in
the considered spacetimes do not violate the cosmic censorship hypothesis as
far as the Dirac fields are concerned. The role of horizons that clothes the
singularity in the black hole cases is replaced by repulsive potential barrier
against the propagation of Dirac fields.
| [
{
"created": "Thu, 15 Apr 2010 08:02:49 GMT",
"version": "v1"
},
{
"created": "Wed, 11 Aug 2010 08:01:01 GMT",
"version": "v2"
},
{
"created": "Thu, 16 Sep 2010 12:52:10 GMT",
"version": "v3"
}
] | 2014-11-20 | [
[
"Unver",
"O.",
""
],
[
"Gurtug",
"O.",
""
]
] | Quantum singularities considered in the 3D BTZ spacetime by Pitelli and Letelier (Phys. Rev. D77: 124030, 2008) is extended to charged BTZ and 3D Einstein-Maxwell-dilaton gravity spacetimes. The occurence of naked singularities in the Einstein-Maxwell extension of the BTZ spacetime both in linear and non-linear electrodynamics as well as in the Einstein-Maxwell-dilaton gravity spacetimes are analysed with the quantum test fields obeying the Klein-Gordon and Dirac equations. We show that with the inclusion of the matter fields; the conical geometry near r=0 is removed and restricted classes of solutions are admitted for the Klein-Gordon and Dirac equations. Hence, the classical central singularity at r=0 turns out to be quantum mechanically singular for quantum particles obeying Klein-Gordon equation but nonsingular for fermions obeying Dirac equation. Explicit calculations reveal that the occurrence of the timelike naked singularities in the considered spacetimes do not violate the cosmic censorship hypothesis as far as the Dirac fields are concerned. The role of horizons that clothes the singularity in the black hole cases is replaced by repulsive potential barrier against the propagation of Dirac fields. |
2407.12732 | Sergey Yu. Vernov | Vsevolod R. Ivanov and Sergey Yu. Vernov | New Integrable Chiral Cosmological Models with Two Scalar Fields | 18 pages | null | null | null | gr-qc astro-ph.CO math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct integrable chiral cosmological models with two scalar fields and
potentials represented in terms of hyperbolic functions. Using the conformal
transformation of the metric and the corresponding models with induced gravity
terms, we obtain the general solutions in the spatially flat, open and closed
Friedmann universes and the corresponding integrals of motion. The obtained
general solutions can be written in terms of the Jacobi elliptic functions of
the conformal time.
| [
{
"created": "Wed, 17 Jul 2024 16:51:10 GMT",
"version": "v1"
}
] | 2024-07-18 | [
[
"Ivanov",
"Vsevolod R.",
""
],
[
"Vernov",
"Sergey Yu.",
""
]
] | We construct integrable chiral cosmological models with two scalar fields and potentials represented in terms of hyperbolic functions. Using the conformal transformation of the metric and the corresponding models with induced gravity terms, we obtain the general solutions in the spatially flat, open and closed Friedmann universes and the corresponding integrals of motion. The obtained general solutions can be written in terms of the Jacobi elliptic functions of the conformal time. |
1904.05084 | Juho Lankinen | Juho Lankinen, Joonas Malmi, Iiro Vilja | Fermionic decay of a massive scalar in the early Universe | 9 pages, 2 figures. Corrected some minor misprints | null | 10.1140/epjc/s10052-020-8074-8 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive a curved space generalization of a scalar to fermion decay rate
with a Yukawa coupling in expanding Friedmann-Robertson-Walker universes. This
is done using the full theory of quantum fields in curved spacetime and the
added-up transition probability method. It is found that in an expanding
universe the usual Minkowskian decay rates are considerably modified for early
times. For conformally coupled scalars the decay rate is modified by a positive
additive term proportional to the inverse of mass and related to the expansion
rate of the Universe. We compare and contrast our results with previous studies
on scalar to scalar decay and find that in general the decay channel into
fermions is the dominant channel of decay in the very early Universe.
| [
{
"created": "Wed, 10 Apr 2019 09:29:43 GMT",
"version": "v1"
},
{
"created": "Tue, 23 Apr 2019 09:34:57 GMT",
"version": "v2"
}
] | 2020-06-09 | [
[
"Lankinen",
"Juho",
""
],
[
"Malmi",
"Joonas",
""
],
[
"Vilja",
"Iiro",
""
]
] | We derive a curved space generalization of a scalar to fermion decay rate with a Yukawa coupling in expanding Friedmann-Robertson-Walker universes. This is done using the full theory of quantum fields in curved spacetime and the added-up transition probability method. It is found that in an expanding universe the usual Minkowskian decay rates are considerably modified for early times. For conformally coupled scalars the decay rate is modified by a positive additive term proportional to the inverse of mass and related to the expansion rate of the Universe. We compare and contrast our results with previous studies on scalar to scalar decay and find that in general the decay channel into fermions is the dominant channel of decay in the very early Universe. |
2308.01615 | Nigel Bishop | Vishnu Kakkat and Nigel T. Bishop and Amos S. Kubeka | Gravitational Wave Heating | null | Physical Review D, 109, 024013 (2024) | 10.1103/PhysRevD.109.024013 | null | gr-qc | http://creativecommons.org/licenses/by-nc-nd/4.0/ | It was shown in previous work that when a gravitational wave (GW) passes
through a viscous shell of matter the magnitude of the GW will be damped and
there are astrohysical circumstances in which the damping is almost complete.
The energy transfer from the GWs to the fluid will increase its temperature. We
construct a model for this process and obtain an expression for the temperature
distribution inside the shell in terms of spherical harmonics. Further, it is
shown that this effect is astrophysically significant: a model problem is
constructed for which the temperature increase is of order $10^6{}^\circ$K.
| [
{
"created": "Thu, 3 Aug 2023 08:42:48 GMT",
"version": "v1"
},
{
"created": "Thu, 11 Jan 2024 13:24:28 GMT",
"version": "v2"
}
] | 2024-01-12 | [
[
"Kakkat",
"Vishnu",
""
],
[
"Bishop",
"Nigel T.",
""
],
[
"Kubeka",
"Amos S.",
""
]
] | It was shown in previous work that when a gravitational wave (GW) passes through a viscous shell of matter the magnitude of the GW will be damped and there are astrohysical circumstances in which the damping is almost complete. The energy transfer from the GWs to the fluid will increase its temperature. We construct a model for this process and obtain an expression for the temperature distribution inside the shell in terms of spherical harmonics. Further, it is shown that this effect is astrophysically significant: a model problem is constructed for which the temperature increase is of order $10^6{}^\circ$K. |
gr-qc/0302011 | Izzet Sakalli | M.Halilsoy and I.Sakalli | Scalar Field Solutions in Colliding Einstein-Maxwell Waves | Letter/5 pages | null | null | null | gr-qc | null | A simple method is presented which enables us to construct scalar field
solutions from any given Einstein-Maxwell solution in colliding plane waves. As
an application we give scalar field extensions of the solution found by Hogan,
Barrabes and Bressange.
| [
{
"created": "Tue, 4 Feb 2003 10:41:32 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Halilsoy",
"M.",
""
],
[
"Sakalli",
"I.",
""
]
] | A simple method is presented which enables us to construct scalar field solutions from any given Einstein-Maxwell solution in colliding plane waves. As an application we give scalar field extensions of the solution found by Hogan, Barrabes and Bressange. |
1110.2775 | Jos\'e Antonio Belinch\'on | Jos\'e Antonio Belinch\'on | (An)Isotropic models in scalar and scalar-tensor cosmologies | null | Astrophys Space Sci (2012) 338:381-400 | 10.1007/s10509-011-0954-9 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study how the constants $G$ and $\Lambda$ may vary in different
theoretical models (general relativity with a perfect fluid, scalar
cosmological models (\textquotedblleft quintessence\textquotedblright) with and
without interacting scalar and matter fields and a scalar-tensor model with a
dynamical $\Lambda$) in order to explain some observational results. We apply
the program outlined in section II to study three different geometries which
generalize the FRW ones, which are Bianchi \textrm{V}, \textrm{VII}$_{0}$ and
\textrm{IX}, under the self-similarity hypothesis. We put special emphasis on
calculating exact power-law solutions which allow us to compare the different
models. In all the studied cases we arrive to the conclusion that the solutions
are isotropic and noninflationary while the cosmological constant behaves as a
positive decreasing time function (in agreement with the current observations)
and the gravitational constant behaves as a growing time function.
| [
{
"created": "Wed, 12 Oct 2011 15:22:26 GMT",
"version": "v1"
}
] | 2012-04-06 | [
[
"Belinchón",
"José Antonio",
""
]
] | We study how the constants $G$ and $\Lambda$ may vary in different theoretical models (general relativity with a perfect fluid, scalar cosmological models (\textquotedblleft quintessence\textquotedblright) with and without interacting scalar and matter fields and a scalar-tensor model with a dynamical $\Lambda$) in order to explain some observational results. We apply the program outlined in section II to study three different geometries which generalize the FRW ones, which are Bianchi \textrm{V}, \textrm{VII}$_{0}$ and \textrm{IX}, under the self-similarity hypothesis. We put special emphasis on calculating exact power-law solutions which allow us to compare the different models. In all the studied cases we arrive to the conclusion that the solutions are isotropic and noninflationary while the cosmological constant behaves as a positive decreasing time function (in agreement with the current observations) and the gravitational constant behaves as a growing time function. |
2212.05822 | Nobuyoshi Komatsu | Nobuyoshi Komatsu | Horizon thermodynamics and cosmological equations: A holographic-like
connection between thermostatistical quantities on a cosmological horizon and
in the bulk | Final version accepted for publication in EPJC. Several paragraphs
and references are added. [10 pages] | Eur. Phys. J. C 83, 690 (2023) | 10.1140/epjc/s10052-023-11855-7 | null | gr-qc astro-ph.CO hep-ph | http://creativecommons.org/licenses/by-nc-nd/4.0/ | Horizon thermodynamics is expected to be related to the effective energy
based on the energy density calculated from the Friedmann equation for a
Friedmann--Robertson--Walker (FRW) universe. In the present study, the
effective energy and thermostatistical quantities on a cosmological horizon are
examined to clarify the holographic-like connection between them, with a focus
on a de Sitter universe. To this end, the Helmholtz free energy on the horizon
is derived from horizon thermodynamics. The free energy is found to be
equivalent to the effective energy calculated from the Friedmann equation. This
consistency is interpreted as a kind of holographic-like connection. To examine
this connection, Padmanabhan's holographic equipartition law, which is related
to the origin of spacetime dynamics, is applied to a de Sitter universe. It is
found that the law should lead to a holographic-like connection. The
holographic-like connection is considered to be a bridge between
thermostatistical quantities on the horizon and in the bulk. For example,
cosmological equations for a flat FRW universe can be derived from horizon
thermodynamics by accepting the connection as a viable scenario. In addition, a
thermal entropy equivalent to the Bekenstein--Hawking entropy is obtained from
the Friedmann equation using the concept of a canonical ensemble in statistical
physics. The present study provides new insight into the discussion of horizon
thermodynamics and cosmological equations.
| [
{
"created": "Mon, 12 Dec 2022 10:42:10 GMT",
"version": "v1"
},
{
"created": "Sun, 23 Jul 2023 23:26:38 GMT",
"version": "v2"
}
] | 2023-08-07 | [
[
"Komatsu",
"Nobuyoshi",
""
]
] | Horizon thermodynamics is expected to be related to the effective energy based on the energy density calculated from the Friedmann equation for a Friedmann--Robertson--Walker (FRW) universe. In the present study, the effective energy and thermostatistical quantities on a cosmological horizon are examined to clarify the holographic-like connection between them, with a focus on a de Sitter universe. To this end, the Helmholtz free energy on the horizon is derived from horizon thermodynamics. The free energy is found to be equivalent to the effective energy calculated from the Friedmann equation. This consistency is interpreted as a kind of holographic-like connection. To examine this connection, Padmanabhan's holographic equipartition law, which is related to the origin of spacetime dynamics, is applied to a de Sitter universe. It is found that the law should lead to a holographic-like connection. The holographic-like connection is considered to be a bridge between thermostatistical quantities on the horizon and in the bulk. For example, cosmological equations for a flat FRW universe can be derived from horizon thermodynamics by accepting the connection as a viable scenario. In addition, a thermal entropy equivalent to the Bekenstein--Hawking entropy is obtained from the Friedmann equation using the concept of a canonical ensemble in statistical physics. The present study provides new insight into the discussion of horizon thermodynamics and cosmological equations. |
gr-qc/9711064 | Marcelo Jose Reboucas | J.E. Aman, J.B. Fonseca-Neto, M.A.H. MacCallum and M.J. Reboucas | Riemann-Cartan Space-times of G\"odel Type | 24 pages, LaTeX file | Class.Quant.Grav.15:1089-1101,1998 | 10.1088/0264-9381/15/4/026 | CBPF-NF-047/97 | gr-qc astro-ph | null | A class of Riemann-Cartan G\"odel-type space-times are examined in the light
of the equivalence problem techniques. The conditions for local space-time
homogeneity are derived, generalizing previous works on Riemannian G\"odel-type
space-times. The equivalence of Riemann-Cartan G\"odel-type space-times of this
class is studied. It is shown that they admit a five-dimensional group of
affine-isometries and are characterized by three essential parameters $\ell,
m^2, \omega$: identical triads ($\ell, m^2, \omega$) correspond to locally
equivalent manifolds. The algebraic types of the irreducible parts of the
curvature and torsion tensors are also presented.
| [
{
"created": "Thu, 20 Nov 1997 20:51:31 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Aman",
"J. E.",
""
],
[
"Fonseca-Neto",
"J. B.",
""
],
[
"MacCallum",
"M. A. H.",
""
],
[
"Reboucas",
"M. J.",
""
]
] | A class of Riemann-Cartan G\"odel-type space-times are examined in the light of the equivalence problem techniques. The conditions for local space-time homogeneity are derived, generalizing previous works on Riemannian G\"odel-type space-times. The equivalence of Riemann-Cartan G\"odel-type space-times of this class is studied. It is shown that they admit a five-dimensional group of affine-isometries and are characterized by three essential parameters $\ell, m^2, \omega$: identical triads ($\ell, m^2, \omega$) correspond to locally equivalent manifolds. The algebraic types of the irreducible parts of the curvature and torsion tensors are also presented. |
1610.02810 | Andrew Finch | Andrew Finch and Jackson Levi Said | Gravitomagnetic effects in quadratic gravity with a scalar field | 7 pages | Phys. Rev. D 94, 084010 (2016) | 10.1103/PhysRevD.94.084010 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The two gravitomagnetic effects which influence bodies orbiting around a
gravitational source are the geodetic effect and the Lense-Thirring effect. The
former describes the precession angle of the axis of a spinning gyroscope while
in orbit around a nonrotating gravitational source whereas the latter provides
a correction for this angle in the case of a spinning source. In this paper we
derive the relevant equations in quadratic gravity and relate them to their
equivalents in general relativity. Starting with an investigation into Kepler's
third law in quadratic gravity with a scalar field, the effects of an
axisymmetric and rotating gravitational source on an orbiting body in a
circular, equatorial orbit are introduced.
| [
{
"created": "Mon, 10 Oct 2016 08:59:37 GMT",
"version": "v1"
}
] | 2016-10-11 | [
[
"Finch",
"Andrew",
""
],
[
"Said",
"Jackson Levi",
""
]
] | The two gravitomagnetic effects which influence bodies orbiting around a gravitational source are the geodetic effect and the Lense-Thirring effect. The former describes the precession angle of the axis of a spinning gyroscope while in orbit around a nonrotating gravitational source whereas the latter provides a correction for this angle in the case of a spinning source. In this paper we derive the relevant equations in quadratic gravity and relate them to their equivalents in general relativity. Starting with an investigation into Kepler's third law in quadratic gravity with a scalar field, the effects of an axisymmetric and rotating gravitational source on an orbiting body in a circular, equatorial orbit are introduced. |
1609.01632 | Simone Speziale | Simone Speziale | Boosting Wigner's nj-symbols | 35 pages, many figures. v2: many improvements, in particular
clarifications on different options for the phases of the CG coefficients | null | 10.1063/1.4977752 | null | gr-qc hep-th math-ph math.GR math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the SL(2,C) Clebsch-Gordan coefficients appearing in the lorentzian
EPRL spin foam amplitudes for loop quantum gravity. We show how the amplitudes
decompose into SU(2) nj-symbols at the vertices and integrals over boosts at
the edges. The integrals define edge amplitudes that can be evaluated
analytically using and adapting results in the literature, leading to a pure
state sum model formulation. This procedure introduces virtual representations
which, in a manner reminiscent to virtual momenta in Feynman amplitudes, are
off-shell of the simplicity constraints present in the theory, but with the
integrands that peak at the on-shell values. We point out some properties of
the edge amplitudes which are helpful for numerical and analytical evaluations
of spin foam amplitudes, and suggest among other things a simpler model useful
for calculations of certain lowest order amplitudes. As an application, we
estimate the large spin scaling behaviour of the simpler model, on a closed
foam with all 4-valent edges and Euler characteristic X, to be N^(X - 5E +
V/2). The paper contains a review and an extension of results on SL(2,C)
Clebsch-Gordan coefficients among unitary representations of the principal
series that can be useful beyond their application to quantum gravity
considered here.
| [
{
"created": "Tue, 6 Sep 2016 16:06:49 GMT",
"version": "v1"
},
{
"created": "Thu, 8 Dec 2016 11:10:42 GMT",
"version": "v2"
}
] | 2017-04-05 | [
[
"Speziale",
"Simone",
""
]
] | We study the SL(2,C) Clebsch-Gordan coefficients appearing in the lorentzian EPRL spin foam amplitudes for loop quantum gravity. We show how the amplitudes decompose into SU(2) nj-symbols at the vertices and integrals over boosts at the edges. The integrals define edge amplitudes that can be evaluated analytically using and adapting results in the literature, leading to a pure state sum model formulation. This procedure introduces virtual representations which, in a manner reminiscent to virtual momenta in Feynman amplitudes, are off-shell of the simplicity constraints present in the theory, but with the integrands that peak at the on-shell values. We point out some properties of the edge amplitudes which are helpful for numerical and analytical evaluations of spin foam amplitudes, and suggest among other things a simpler model useful for calculations of certain lowest order amplitudes. As an application, we estimate the large spin scaling behaviour of the simpler model, on a closed foam with all 4-valent edges and Euler characteristic X, to be N^(X - 5E + V/2). The paper contains a review and an extension of results on SL(2,C) Clebsch-Gordan coefficients among unitary representations of the principal series that can be useful beyond their application to quantum gravity considered here. |
1708.07001 | Justin Feng | Justin C. Feng, Richard A. Matzner | From path integrals to the Wheeler-DeWitt equation: Time evolution in
spacetimes with a spatial boundary | Revised to match published version in Phys. Rev. D | Phys. Rev. D 96, 106005 (2017) | 10.1103/PhysRevD.96.106005 | UTTG-08-17 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We reexamine the relationship between the path integral and canonical
formulation of quantum general relativity. In particular, we present a formal
derivation of the Wheeler-DeWitt equation from the path integral for quantum
general relativity by way of boundary variations. One feature of this approach
is that it does not require an explicit 3+1 splitting of spacetime in the bulk.
For spacetimes with a spatial boundary, we show that the dependence of the
transition amplitudes on spatial boundary conditions is determined by a
Wheeler-DeWitt equation for the spatial boundary surface. We find that
variations in the induced metric at the spatial boundary can be used to
describe time evolution---time evolution in quantum general relativity is
therefore governed by boundary conditions on the gravitational field at the
spatial boundary. We then briefly describe a formalism for computing the
dependence of transition amplitudes on spatial boundary conditions. Finally, we
argue that for nonsmooth boundaries, meaningful transition amplitudes must
depend on boundary conditions at the joint surfaces.
| [
{
"created": "Mon, 21 Aug 2017 20:48:31 GMT",
"version": "v1"
},
{
"created": "Wed, 6 Sep 2017 20:06:37 GMT",
"version": "v2"
},
{
"created": "Thu, 12 Oct 2017 15:54:44 GMT",
"version": "v3"
},
{
"created": "Mon, 13 Nov 2017 02:09:36 GMT",
"version": "v4"
}
] | 2017-11-15 | [
[
"Feng",
"Justin C.",
""
],
[
"Matzner",
"Richard A.",
""
]
] | We reexamine the relationship between the path integral and canonical formulation of quantum general relativity. In particular, we present a formal derivation of the Wheeler-DeWitt equation from the path integral for quantum general relativity by way of boundary variations. One feature of this approach is that it does not require an explicit 3+1 splitting of spacetime in the bulk. For spacetimes with a spatial boundary, we show that the dependence of the transition amplitudes on spatial boundary conditions is determined by a Wheeler-DeWitt equation for the spatial boundary surface. We find that variations in the induced metric at the spatial boundary can be used to describe time evolution---time evolution in quantum general relativity is therefore governed by boundary conditions on the gravitational field at the spatial boundary. We then briefly describe a formalism for computing the dependence of transition amplitudes on spatial boundary conditions. Finally, we argue that for nonsmooth boundaries, meaningful transition amplitudes must depend on boundary conditions at the joint surfaces. |
2003.10127 | Shantanu Desai | Aditi Krishak, Shantanu Desai | Model Comparison tests of modified gravity from the E\"ot-Wash
experiment | 13 pages, 1 figure. Link to analysis code available at
https://github.com/aditikrishak/EotWash_analysis | JCAP 07 (2020) 006 | 10.1088/1475-7516/2020/07/006 | null | gr-qc astro-ph.CO astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Perivolaropoulos et al (arXiv:1904.09462) (P19) have argued that the residual
torque data in the E\"ot-Wash experiment is consistent with an oscillating
signal. This could either be a signature of non-local modified gravity theories
or some other systematic error in the data. We independently assess the
viability of such an oscillating signal in the same data using Bayesian and
information theoretical criterion, to complement the frequentist analysis in
P19. We fit this data to three different parametrizations (an offset Newtonian,
Yukawa, and an oscillating model), and assess the significance of the
oscillating model using AIC, BIC, WAIC, and Bayes factor. All these techniques
provide decisive evidence for the oscillating model compared to the Newtonian
model, provided the phase is fixed to the same value as in P19. If the phase is
allowed to vary, then significance from BIC, WAIC, and Bayes based tests
reduces to strong evidence, whereas only AIC still shows decisive evidence. Our
analysis codes have been made publicly available.
| [
{
"created": "Mon, 23 Mar 2020 08:25:06 GMT",
"version": "v1"
},
{
"created": "Tue, 24 Mar 2020 13:06:35 GMT",
"version": "v2"
},
{
"created": "Sun, 7 Jun 2020 15:09:50 GMT",
"version": "v3"
}
] | 2020-07-03 | [
[
"Krishak",
"Aditi",
""
],
[
"Desai",
"Shantanu",
""
]
] | Perivolaropoulos et al (arXiv:1904.09462) (P19) have argued that the residual torque data in the E\"ot-Wash experiment is consistent with an oscillating signal. This could either be a signature of non-local modified gravity theories or some other systematic error in the data. We independently assess the viability of such an oscillating signal in the same data using Bayesian and information theoretical criterion, to complement the frequentist analysis in P19. We fit this data to three different parametrizations (an offset Newtonian, Yukawa, and an oscillating model), and assess the significance of the oscillating model using AIC, BIC, WAIC, and Bayes factor. All these techniques provide decisive evidence for the oscillating model compared to the Newtonian model, provided the phase is fixed to the same value as in P19. If the phase is allowed to vary, then significance from BIC, WAIC, and Bayes based tests reduces to strong evidence, whereas only AIC still shows decisive evidence. Our analysis codes have been made publicly available. |
1305.6712 | Jia-An Lu | Jia-An Lu, Chao-Guang Huang | Weak field approximation in a model of de Sitter gravity:
Schwarzschild-de Sitter solutions | 15 pages. arXiv admin note: text overlap with arXiv:1301.5796 | Int. J. Mod. Phys. D 2013 22 (7) 1350048 | 10.1142/S021827181350048X | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The weak field approximation in a model of de Sitter gravity is investigated
in the static and spherically symmetric case, under the assumption that the
vacuum spacetime without perturbations from matter fields is a torsion-free de
Sitter spacetime. It is shown on one hand that any solution should be singular
at the center of the matter field, if the exterior is described by a
Schwarzschild-de Sitter spacetime and is smoothly connected to the interior. On
the other, all the regular solutions are obtained, which might be used to
explain the galactic rotation curves without involving dark matter.
| [
{
"created": "Wed, 29 May 2013 07:55:26 GMT",
"version": "v1"
}
] | 2013-06-12 | [
[
"Lu",
"Jia-An",
""
],
[
"Huang",
"Chao-Guang",
""
]
] | The weak field approximation in a model of de Sitter gravity is investigated in the static and spherically symmetric case, under the assumption that the vacuum spacetime without perturbations from matter fields is a torsion-free de Sitter spacetime. It is shown on one hand that any solution should be singular at the center of the matter field, if the exterior is described by a Schwarzschild-de Sitter spacetime and is smoothly connected to the interior. On the other, all the regular solutions are obtained, which might be used to explain the galactic rotation curves without involving dark matter. |
gr-qc/9709055 | Takashi Tamaki | Takashi Tamaki, Takashi Torii and Kei-ichi Maeda | Non-Abelian Black Holes in Brans-Dicke Theory | 31 pages, revtex, 21 figures | Phys.Rev.D57:4870-4884,1998 | 10.1103/PhysRevD.57.4870 | WU-AP/66/97 | gr-qc hep-th | null | We find a black hole solution with non-Abelian field in Brans-Dicke theory.
It is an extension of non-Abelian black hole in general relativity. We discuss
two non-Abelian fields: "SU(2)" Yang-Mills field with a mass (Proca field) and
the SU(2)$\times$SU(2) Skyrme field. In both cases, as in general relativity,
there are two branches of solutions, i.e., two black hole solutions with the
same horizon radius. Masses of both black holes are always smaller than those
in general relativity. A cusp structure in the mass-horizon radius
($M_{g}$-$r_{h}$) diagram, which is a typical symptom of stability change in
catastrophe theory, does not appear in the Brans-Dicke frame but is found in
the Einstein conformal frame. This suggests that catastrophe theory may be
simply applied for a stability analysis as it is if we use the variables in the
Einstein frame. We also discuss the effects of the Brans-Dicke scalar field on
black hole structure.
| [
{
"created": "Mon, 22 Sep 1997 08:08:13 GMT",
"version": "v1"
}
] | 2011-07-19 | [
[
"Tamaki",
"Takashi",
""
],
[
"Torii",
"Takashi",
""
],
[
"Maeda",
"Kei-ichi",
""
]
] | We find a black hole solution with non-Abelian field in Brans-Dicke theory. It is an extension of non-Abelian black hole in general relativity. We discuss two non-Abelian fields: "SU(2)" Yang-Mills field with a mass (Proca field) and the SU(2)$\times$SU(2) Skyrme field. In both cases, as in general relativity, there are two branches of solutions, i.e., two black hole solutions with the same horizon radius. Masses of both black holes are always smaller than those in general relativity. A cusp structure in the mass-horizon radius ($M_{g}$-$r_{h}$) diagram, which is a typical symptom of stability change in catastrophe theory, does not appear in the Brans-Dicke frame but is found in the Einstein conformal frame. This suggests that catastrophe theory may be simply applied for a stability analysis as it is if we use the variables in the Einstein frame. We also discuss the effects of the Brans-Dicke scalar field on black hole structure. |
1006.1762 | Kensuke Homma | Yasunori Fujii and Kensuke Homma | An approach toward the laboratory search for the scalar field as a
candidate of Dark Energy | 20 pages, 6 figure. Accepted by Progress of Theoretical Physics | Prog. Theor. Phys. 126 (2011), 531-553 | 10.1143/PTP.126.531 | null | gr-qc hep-ph quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The observed accelerating universe indicates the presence of Dark Energy
which is probably interpreted in terms of an extremely light gravitational
scalar field. We suggest a way to probe this scalar field which contributes to
optical light-by-light scattering through the resonance in the quasi-parallel
collision geometry. As we find, the frequency-shifted photons with the
specifically chosen polarization state can be a distinct signature of the
scalar-field-exchange process in spite of the extremely narrow width due to the
gravitationally weak coupling to photons. Main emphasis will be placed in
formulating a prototype theoretical approach, then showing how the weak signals
from the gravitational coupling are enhanced by other non-gravitational effects
at work in laser experiments.
| [
{
"created": "Wed, 9 Jun 2010 10:36:32 GMT",
"version": "v1"
},
{
"created": "Wed, 9 Mar 2011 16:39:12 GMT",
"version": "v2"
},
{
"created": "Sat, 20 Aug 2011 21:46:56 GMT",
"version": "v3"
}
] | 2011-11-03 | [
[
"Fujii",
"Yasunori",
""
],
[
"Homma",
"Kensuke",
""
]
] | The observed accelerating universe indicates the presence of Dark Energy which is probably interpreted in terms of an extremely light gravitational scalar field. We suggest a way to probe this scalar field which contributes to optical light-by-light scattering through the resonance in the quasi-parallel collision geometry. As we find, the frequency-shifted photons with the specifically chosen polarization state can be a distinct signature of the scalar-field-exchange process in spite of the extremely narrow width due to the gravitationally weak coupling to photons. Main emphasis will be placed in formulating a prototype theoretical approach, then showing how the weak signals from the gravitational coupling are enhanced by other non-gravitational effects at work in laser experiments. |
gr-qc/0012076 | Hod Shahar | Shahar Hod | Discrete Black-Hole Radiation and the Information Loss Paradox | 12 pages | Phys.Lett. A299 (2002) 144-148 | 10.1016/S0375-9601(02)00013-0 | null | gr-qc hep-th quant-ph | null | Hawking's black hole information puzzle highlights the incompatibility
between our present understanding of gravity and quantum physics. However,
Hawking's prediction of black-hole evaporation is at a semiclassical level. One
therefore suspects some modifications of the character of the radiation when
quantum properties of the {\it black hole itself} are properly taken into
account. In fact, during the last three decades evidence has been mounting
that, in a quantum theory of gravity black holes may have a discrete mass
spectrum, with concomitant {\it discrete} line emission. A direct consequence
of this intriguing prediction is that, compared with blackbody radiation,
black-hole radiance is {\it less} entropic, and may therefore carry a
significant amount of {\it information}. Using standard ideas from quantum
information theory, we calculate the rate at which information can be recovered
from the black-hole spectral lines. We conclude that the information that was
suspected to be lost may gradually leak back, encoded into the black-hole
spectral lines.
| [
{
"created": "Wed, 20 Dec 2000 08:52:55 GMT",
"version": "v1"
},
{
"created": "Mon, 24 Jun 2002 08:07:50 GMT",
"version": "v2"
},
{
"created": "Tue, 25 Jun 2002 08:04:21 GMT",
"version": "v3"
}
] | 2015-06-25 | [
[
"Hod",
"Shahar",
""
]
] | Hawking's black hole information puzzle highlights the incompatibility between our present understanding of gravity and quantum physics. However, Hawking's prediction of black-hole evaporation is at a semiclassical level. One therefore suspects some modifications of the character of the radiation when quantum properties of the {\it black hole itself} are properly taken into account. In fact, during the last three decades evidence has been mounting that, in a quantum theory of gravity black holes may have a discrete mass spectrum, with concomitant {\it discrete} line emission. A direct consequence of this intriguing prediction is that, compared with blackbody radiation, black-hole radiance is {\it less} entropic, and may therefore carry a significant amount of {\it information}. Using standard ideas from quantum information theory, we calculate the rate at which information can be recovered from the black-hole spectral lines. We conclude that the information that was suspected to be lost may gradually leak back, encoded into the black-hole spectral lines. |
1006.2226 | Ujjal Debnath | Surajit Chattopadhyay and Ujjal Debnath | Interaction between DBI-essence and other Dark Energies | 13 pages, 18 figures | Int.J.Theor.Phys.49:1465-1480,2010 | 10.1007/s10773-010-0328-z | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The present work considers interaction between DBI-essence and other
candidates of dark energies like modified Chaplygin gas, hessence, tachyonic
field, and new agegraphic dark energy. The potentials of the fields have been
reconstructed under interaction and their evolutions have been viewed against
cosmic time $t$ and scalar field $\phi$. Equation of state parameters have also
been obtained. The nature of potentials and the equation of state parameters of
the dark energies have been found graphically in presence of interaction (both
small and large interaction).
| [
{
"created": "Fri, 11 Jun 2010 08:15:04 GMT",
"version": "v1"
}
] | 2014-11-21 | [
[
"Chattopadhyay",
"Surajit",
""
],
[
"Debnath",
"Ujjal",
""
]
] | The present work considers interaction between DBI-essence and other candidates of dark energies like modified Chaplygin gas, hessence, tachyonic field, and new agegraphic dark energy. The potentials of the fields have been reconstructed under interaction and their evolutions have been viewed against cosmic time $t$ and scalar field $\phi$. Equation of state parameters have also been obtained. The nature of potentials and the equation of state parameters of the dark energies have been found graphically in presence of interaction (both small and large interaction). |
0903.3505 | Peter Breitenlohner | Peter Breitenlohner and D. H. Tchrakian | Gravitating BPS Monopoles in all d=4p Spacetime Dimensions | 31 pages, 9 figures | Class.Quant.Grav.26:145008,2009 | 10.1088/0264-9381/26/14/145008 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We have constructed, numerically, both regular and black hole static
solutions to the simplest possible gravitating Yang-Mills--Higgs (YMH) in $4p$
spacetime dimensions. The YMH systems consist of $2p-$th power curvature fields
without a Higgs potential. The gravitational systems consist of the `Ricci
scalar' of the $p-$th power of the Riemann curvature. In 4 spacetime dimensions
this is the usual Einstein-YMH (EYMH) studied in \cite{Breitenlohner:1991aa,
Breitenlohner:1994di}, whose qualitative results we emulate exactly.
| [
{
"created": "Fri, 20 Mar 2009 12:46:27 GMT",
"version": "v1"
}
] | 2014-11-18 | [
[
"Breitenlohner",
"Peter",
""
],
[
"Tchrakian",
"D. H.",
""
]
] | We have constructed, numerically, both regular and black hole static solutions to the simplest possible gravitating Yang-Mills--Higgs (YMH) in $4p$ spacetime dimensions. The YMH systems consist of $2p-$th power curvature fields without a Higgs potential. The gravitational systems consist of the `Ricci scalar' of the $p-$th power of the Riemann curvature. In 4 spacetime dimensions this is the usual Einstein-YMH (EYMH) studied in \cite{Breitenlohner:1991aa, Breitenlohner:1994di}, whose qualitative results we emulate exactly. |
1309.0544 | Tanja Hinderer | Tanja Hinderer, Alessandra Buonanno, Abdul H. Mrou\'e, Daniel A.
Hemberger, Geoffrey Lovelace, Harald P. Pfeiffer, Lawrence E. Kidder, Mark A.
Scheel, Bela Szilagyi, Nicholas W. Taylor, and Saul A. Teukolsky | Periastron advance in spinning black hole binaries: comparing
effective-one-body and Numerical Relativity | minor changes to match published version | null | 10.1103/PhysRevD.88.084005 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compute the periastron advance using the effective-one-body formalism for
binary black holes moving on quasi-circular orbits and having spins collinear
with the orbital angular momentum. We compare the predictions with the
periastron advance recently computed in accurate numerical-relativity
simulations and find remarkable agreement for a wide range of spins and mass
ratios. These results do not use any numerical-relativity calibration of the
effective-one-body model, and stem from two key ingredients in the
effective-one-body Hamiltonian: (i) the mapping of the two-body dynamics of
spinning particles onto the dynamics of an effective spinning particle in a
(deformed) Kerr spacetime, fully symmetrized with respect to the two-body
masses and spins, and (ii) the resummation, in the test-particle limit, of all
post-Newtonian (PN) corrections linear in the spin of the particle. In fact,
even when only the leading spin PN corrections are included in the
effective-one-body spinning Hamiltonian but all the test-particle corrections
linear in the spin of the particle are resummed we find very good agreement
with the numerical results (within the numerical error for equal-mass binaries
and discrepancies of at most 1% for larger mass ratios). Furthermore, we
specialize to the extreme mass-ratio limit and derive, using the equations of
motion in the gravitational skeleton approach, analytical expressions for the
periastron advance, the meridional Lense-Thirring precession and spin
precession frequency in the case of a spinning particle on a nearly circular
equatorial orbit in Kerr spacetime, including also terms quadratic in the spin.
| [
{
"created": "Mon, 2 Sep 2013 21:03:17 GMT",
"version": "v1"
},
{
"created": "Tue, 1 Oct 2013 21:27:14 GMT",
"version": "v2"
},
{
"created": "Sat, 16 Nov 2013 21:14:44 GMT",
"version": "v3"
}
] | 2015-06-17 | [
[
"Hinderer",
"Tanja",
""
],
[
"Buonanno",
"Alessandra",
""
],
[
"Mroué",
"Abdul H.",
""
],
[
"Hemberger",
"Daniel A.",
""
],
[
"Lovelace",
"Geoffrey",
""
],
[
"Pfeiffer",
"Harald P.",
""
],
[
"Kidder",
"Lawrence E.",
""
],
[
"Scheel",
"Mark A.",
""
],
[
"Szilagyi",
"Bela",
""
],
[
"Taylor",
"Nicholas W.",
""
],
[
"Teukolsky",
"Saul A.",
""
]
] | We compute the periastron advance using the effective-one-body formalism for binary black holes moving on quasi-circular orbits and having spins collinear with the orbital angular momentum. We compare the predictions with the periastron advance recently computed in accurate numerical-relativity simulations and find remarkable agreement for a wide range of spins and mass ratios. These results do not use any numerical-relativity calibration of the effective-one-body model, and stem from two key ingredients in the effective-one-body Hamiltonian: (i) the mapping of the two-body dynamics of spinning particles onto the dynamics of an effective spinning particle in a (deformed) Kerr spacetime, fully symmetrized with respect to the two-body masses and spins, and (ii) the resummation, in the test-particle limit, of all post-Newtonian (PN) corrections linear in the spin of the particle. In fact, even when only the leading spin PN corrections are included in the effective-one-body spinning Hamiltonian but all the test-particle corrections linear in the spin of the particle are resummed we find very good agreement with the numerical results (within the numerical error for equal-mass binaries and discrepancies of at most 1% for larger mass ratios). Furthermore, we specialize to the extreme mass-ratio limit and derive, using the equations of motion in the gravitational skeleton approach, analytical expressions for the periastron advance, the meridional Lense-Thirring precession and spin precession frequency in the case of a spinning particle on a nearly circular equatorial orbit in Kerr spacetime, including also terms quadratic in the spin. |
0710.5572 | Christian Schubert | F. Bastianelli, U. Nucamendi, C. Schubert, V.M. Villanueva | One loop photon-graviton mixing in an electromagnetic field: Part 2 | 31 pages, 3 figures | JHEP0711:099,2007 | 10.1088/1126-6708/2007/11/099 | AEI-2005-137 | gr-qc hep-th | null | In part 1 of this series compact integral representations had been obtained
for the one-loop photon-graviton amplitude involving a charged spin 0 or spin
1/2 particle in the loop and an arbitrary constant electromagnetic field. In
this sequel, we study the structure and magnitude of the various polarization
components of this amplitude on-shell. Explicit expressions are obtained for a
number of limiting cases.
| [
{
"created": "Tue, 30 Oct 2007 05:19:14 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Bastianelli",
"F.",
""
],
[
"Nucamendi",
"U.",
""
],
[
"Schubert",
"C.",
""
],
[
"Villanueva",
"V. M.",
""
]
] | In part 1 of this series compact integral representations had been obtained for the one-loop photon-graviton amplitude involving a charged spin 0 or spin 1/2 particle in the loop and an arbitrary constant electromagnetic field. In this sequel, we study the structure and magnitude of the various polarization components of this amplitude on-shell. Explicit expressions are obtained for a number of limiting cases. |
1107.6023 | Michael Koehn | Michael Koehn | Relativistic Wavepackets in Classically Chaotic Quantum Cosmological
Billiards | 18 pages, 10 figures | Phys Rev D 85, 063501 (2012) | 10.1103/PhysRevD.85.063501 | AEI-2011-050 | gr-qc hep-th nlin.CD quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Close to a spacelike singularity, pure gravity and supergravity in four to
eleven spacetime dimensions admit a cosmological billiard description based on
hyperbolic Kac-Moody groups. We investigate the quantum cosmological billiards
of relativistic wavepackets towards the singularity, employing flat and
hyperbolic space descriptions for the quantum billiards. We find that the
strongly chaotic classical billiard motion of four-dimensional pure gravity
corresponds to a spreading wavepacket subject to successive redshifts and
tending to zero as the singularity is approached. We discuss the possible
implications of these results in the context of singularity resolution and
compare them with those of known semiclassical approaches. As an aside, we
obtain exact solutions for the one-dimensional relativistic quantum billiards
with moving walls.
| [
{
"created": "Fri, 29 Jul 2011 17:06:23 GMT",
"version": "v1"
},
{
"created": "Fri, 2 Mar 2012 16:53:04 GMT",
"version": "v2"
}
] | 2012-03-05 | [
[
"Koehn",
"Michael",
""
]
] | Close to a spacelike singularity, pure gravity and supergravity in four to eleven spacetime dimensions admit a cosmological billiard description based on hyperbolic Kac-Moody groups. We investigate the quantum cosmological billiards of relativistic wavepackets towards the singularity, employing flat and hyperbolic space descriptions for the quantum billiards. We find that the strongly chaotic classical billiard motion of four-dimensional pure gravity corresponds to a spreading wavepacket subject to successive redshifts and tending to zero as the singularity is approached. We discuss the possible implications of these results in the context of singularity resolution and compare them with those of known semiclassical approaches. As an aside, we obtain exact solutions for the one-dimensional relativistic quantum billiards with moving walls. |
2008.00649 | Eric De Giuli | Eric De Giuli and A. Zee | Glassy gravity | 5 pages + 4 pages SI | null | 10.1209/0295-5075/133/20008 | null | gr-qc cond-mat.dis-nn hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Euclidean quantum gravity is reconsidered, in the conformal mode
approximation. Applying techniques from glass theory, we argue that the
Euclidean partition function hides metastable states, which can be counted.
This may reconcile conflicting results on the uniqueness of the de Sitter
vacuum, and may be relevant to the cosmological constant problem.
| [
{
"created": "Mon, 3 Aug 2020 05:16:46 GMT",
"version": "v1"
},
{
"created": "Sun, 3 Jan 2021 16:31:09 GMT",
"version": "v2"
}
] | 2021-05-26 | [
[
"De Giuli",
"Eric",
""
],
[
"Zee",
"A.",
""
]
] | Euclidean quantum gravity is reconsidered, in the conformal mode approximation. Applying techniques from glass theory, we argue that the Euclidean partition function hides metastable states, which can be counted. This may reconcile conflicting results on the uniqueness of the de Sitter vacuum, and may be relevant to the cosmological constant problem. |
gr-qc/0010038 | Sergey S. Kokarev | Sergey Kokarev | Space-time as strongly bent plate | 20 pages, LaTEX 2e | Nuovo Cim.B114:903-921,1999 | null | null | gr-qc | null | Futher development is made of a consept of space-time as multidimensional
elastic plate, proposed earlier in [20,21]. General equilibrium equations,
including 4-dimensional tangent stress tensor - energy-momentum tensor of
matter - are derived. Comparative analysis of multidimensional elasticity
theory (MET) and GR is given. Variational principle, boundary conditions,
energy-momentum tensor, matter and space-time signature are reviewed within the
context of MET.
| [
{
"created": "Tue, 10 Oct 2000 14:30:11 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"Kokarev",
"Sergey",
""
]
] | Futher development is made of a consept of space-time as multidimensional elastic plate, proposed earlier in [20,21]. General equilibrium equations, including 4-dimensional tangent stress tensor - energy-momentum tensor of matter - are derived. Comparative analysis of multidimensional elasticity theory (MET) and GR is given. Variational principle, boundary conditions, energy-momentum tensor, matter and space-time signature are reviewed within the context of MET. |
gr-qc/0306084 | Pieter Kok | Pieter Kok and Ulvi Yurtsever | Gravitational decoherence | 13 pages, 4 figures REVTeX | Phys.Rev. D68 (2003) 085006 | 10.1103/PhysRevD.68.085006 | null | gr-qc quant-ph | null | We investigate the effect of quantum metric fluctuations on qubits that are
gravitationally coupled to a background spacetime. In our first example, we
study the propagation of a qubit in flat spacetime whose metric is subject to
flat quantum fluctuations with a Gaussian spectrum. We find that these
fluctuations cause two changes in the state of the qubit: they lead to a phase
drift, as well as the expected exponential suppression (decoherence) of the
off-diagonal terms in the density matrix. Secondly, we calculate the
decoherence of a qubit in a circular orbit around a Schwarzschild black hole.
The no-hair theorems suggest a quantum state for the metric in which the black
hole's mass fluctuates with a thermal spectrum at the Hawking temperature.
Again, we find that the orbiting qubit undergoes decoherence and a phase drift
that both depend on the temperature of the black hole. Thirdly, we study the
interaction of coherent and squeezed gravitational waves with a qubit in
uniform motion. Finally, we investigate the decoherence of an accelerating
qubit in Minkowski spacetime due to the Unruh effect. In this case decoherence
is not due to fluctuations in the metric, but instead is caused by coupling
(which we model with a standard Hamiltonian) between the qubit and the thermal
cloud of Unruh particles bathing it. When the accelerating qubit is entangled
with a stationary partner, the decoherence should induce a corresponding loss
in teleportation fidelity.
| [
{
"created": "Wed, 18 Jun 2003 15:51:46 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Kok",
"Pieter",
""
],
[
"Yurtsever",
"Ulvi",
""
]
] | We investigate the effect of quantum metric fluctuations on qubits that are gravitationally coupled to a background spacetime. In our first example, we study the propagation of a qubit in flat spacetime whose metric is subject to flat quantum fluctuations with a Gaussian spectrum. We find that these fluctuations cause two changes in the state of the qubit: they lead to a phase drift, as well as the expected exponential suppression (decoherence) of the off-diagonal terms in the density matrix. Secondly, we calculate the decoherence of a qubit in a circular orbit around a Schwarzschild black hole. The no-hair theorems suggest a quantum state for the metric in which the black hole's mass fluctuates with a thermal spectrum at the Hawking temperature. Again, we find that the orbiting qubit undergoes decoherence and a phase drift that both depend on the temperature of the black hole. Thirdly, we study the interaction of coherent and squeezed gravitational waves with a qubit in uniform motion. Finally, we investigate the decoherence of an accelerating qubit in Minkowski spacetime due to the Unruh effect. In this case decoherence is not due to fluctuations in the metric, but instead is caused by coupling (which we model with a standard Hamiltonian) between the qubit and the thermal cloud of Unruh particles bathing it. When the accelerating qubit is entangled with a stationary partner, the decoherence should induce a corresponding loss in teleportation fidelity. |
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