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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1707.01333 | Bibhas Majhi Ranjan | Ananya Adhikari, Krishnakanta Bhattacharya, Chandramouli Chowdhury,
Bibhas Ranjan Majhi | Fluctuation-dissipation in accelerated frames | The para above Eq. (6) has been modified, to appear in Phys. Rev. D | Phys. Rev. D 97, 045003 (2018) | 10.1103/PhysRevD.97.045003 | null | gr-qc cond-mat.stat-mech hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An uniformly accelerated (Rindler) observer will detect particles in the
Minkowski vacuum, known as Unruh effect. The spectrum is thermal and the
temperature is given by that of the Killing horizon, which is proportional to
the acceleration. Considering these particles are kept in a thermal bath with
this temperature, we find that the correlation function of the random force due
to radiation acting on the particles as measured by the accelerated frame,
shows the fluctuation-dissipation relation. It is observed that the
correlations, in both ($1+1$) spacetime and ($1+3$) dimensional spacetimes, are
of Brownian type. We discuss the implications of this new observation at the
end.
| [
{
"created": "Wed, 5 Jul 2017 11:48:00 GMT",
"version": "v1"
},
{
"created": "Mon, 10 Jul 2017 09:29:48 GMT",
"version": "v2"
},
{
"created": "Tue, 2 Jan 2018 06:52:18 GMT",
"version": "v3"
},
{
"created": "Fri, 19 Jan 2018 03:41:30 GMT",
"version": "v4"
}
] | 2018-02-07 | [
[
"Adhikari",
"Ananya",
""
],
[
"Bhattacharya",
"Krishnakanta",
""
],
[
"Chowdhury",
"Chandramouli",
""
],
[
"Majhi",
"Bibhas Ranjan",
""
]
] | An uniformly accelerated (Rindler) observer will detect particles in the Minkowski vacuum, known as Unruh effect. The spectrum is thermal and the temperature is given by that of the Killing horizon, which is proportional to the acceleration. Considering these particles are kept in a thermal bath with this temperature, we find that the correlation function of the random force due to radiation acting on the particles as measured by the accelerated frame, shows the fluctuation-dissipation relation. It is observed that the correlations, in both ($1+1$) spacetime and ($1+3$) dimensional spacetimes, are of Brownian type. We discuss the implications of this new observation at the end. |
1909.05588 | Tatyana P. Shestakova | T. P. Shestakova | On the meaning of the wave function of the Universe | 15 pages, 1 figure, to be published in Int. J. Mod. Phys. D | Int. J. Mod. Phys. D28 (2019) 1941009 | 10.1142/S0218271819410098 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The meaning of the wave function of the Universe was actively discussed in
1980s. In most works on quantum cosmology it is accepted that the wave function
is a probability amplitude for the Universe to have some space geometry, or to
be found in some point of the Wheeler superspace. It seems that the wave
function gives maximally objective description compatible with quantum theory.
However, the probability distribution does not depend on time and does not take
into account the existing of our macroscopic evolving Universe. What we wish to
know is how quantum processes in the Early Universe determined the state of the
present Universe in which we are able to observe macroscopic consequences of
these quantum processes. As an alternative to the Wheeler - DeWitt quantum
geometrodynamics we consider the picture that can be obtained in the extended
phase space approach to quantization of gravity. The wave function in this
approach describes different states of the Universe which correspond to
different stages of its evolution.
| [
{
"created": "Thu, 12 Sep 2019 12:05:25 GMT",
"version": "v1"
}
] | 2019-12-20 | [
[
"Shestakova",
"T. P.",
""
]
] | The meaning of the wave function of the Universe was actively discussed in 1980s. In most works on quantum cosmology it is accepted that the wave function is a probability amplitude for the Universe to have some space geometry, or to be found in some point of the Wheeler superspace. It seems that the wave function gives maximally objective description compatible with quantum theory. However, the probability distribution does not depend on time and does not take into account the existing of our macroscopic evolving Universe. What we wish to know is how quantum processes in the Early Universe determined the state of the present Universe in which we are able to observe macroscopic consequences of these quantum processes. As an alternative to the Wheeler - DeWitt quantum geometrodynamics we consider the picture that can be obtained in the extended phase space approach to quantization of gravity. The wave function in this approach describes different states of the Universe which correspond to different stages of its evolution. |
2111.14016 | Matt Visser | Matt Visser (Victoria University of Wellington) | Feynman's i-epsilon prescription, almost real spacetimes, and acceptable
complex spacetimes | V1: 22 pages; 50 references; V2: Now 27 pages; 54 references.
Significant improvement (and restructuring) in presentation; now includes a
tetrad analysis. V3: Now 33 pages; 55 references. Significant pedagogical
improvements, sign conventions more carefully explained and standardized.
This version accepted for publication in JHEP | null | 10.1007/JHEP08(2022)129 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Feynman's i-epsilon prescription for quantum field theoretic propagators has
a quite natural reinterpretation in terms of a slight complex deformation of
the Minkowski spacetime metric. Though originally a strictly flat-space result,
once reinterpreted in this way, these ideas can be naturally extended first to
semi-classical curved-spacetime QFT on a fixed background geometry and then,
(with more work), to fluctuating spacetime geometries. There are intimate
connections with variants of the weak energy condition. We shall take the
Lorentzian signature metric as primary, but note that allowing the complex
deformation to become large leads to a variant of Wick rotation, and more
importantly leads to physically motivated constraints on the configuration
space of acceptable off-shell geometries to include in Feynman's functional
integral when attempting to quantize gravity. Ultimately this observation
allows one to connect the discussion back to recent ideas on "acceptable"
complex metrics, in the Louko-Sorkin and Kontsevich-Segal-Witten sense, with
Lorentzian signature spacetimes occurring exactly on the boundary of the set of
"acceptable" complex metrics. By adopting the tetrad formalism we explicitly
construct the most general set of acceptable complex metrics satisfying the
0-form, 1-form, and 2-form acceptability conditions.
| [
{
"created": "Sun, 28 Nov 2021 01:22:31 GMT",
"version": "v1"
},
{
"created": "Sun, 5 Dec 2021 08:21:01 GMT",
"version": "v2"
},
{
"created": "Wed, 13 Jul 2022 10:03:31 GMT",
"version": "v3"
}
] | 2022-09-07 | [
[
"Visser",
"Matt",
"",
"Victoria University of Wellington"
]
] | Feynman's i-epsilon prescription for quantum field theoretic propagators has a quite natural reinterpretation in terms of a slight complex deformation of the Minkowski spacetime metric. Though originally a strictly flat-space result, once reinterpreted in this way, these ideas can be naturally extended first to semi-classical curved-spacetime QFT on a fixed background geometry and then, (with more work), to fluctuating spacetime geometries. There are intimate connections with variants of the weak energy condition. We shall take the Lorentzian signature metric as primary, but note that allowing the complex deformation to become large leads to a variant of Wick rotation, and more importantly leads to physically motivated constraints on the configuration space of acceptable off-shell geometries to include in Feynman's functional integral when attempting to quantize gravity. Ultimately this observation allows one to connect the discussion back to recent ideas on "acceptable" complex metrics, in the Louko-Sorkin and Kontsevich-Segal-Witten sense, with Lorentzian signature spacetimes occurring exactly on the boundary of the set of "acceptable" complex metrics. By adopting the tetrad formalism we explicitly construct the most general set of acceptable complex metrics satisfying the 0-form, 1-form, and 2-form acceptability conditions. |
2201.13163 | Parth Bambhaniya | Siddharth Madan, Parth Bambhaniya | Tidal force effects and periodic orbits in null naked singularity
spacetime | 9 pages, 10 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Naked singularities form during the gravitational collapse of inhomogeneous
matter clouds. The final nature of the singularity depends on the initial
conditions of the matter properties and types of matter profiles. These naked
singularities can also be divided into two types: null-like and timelike
singularities. The spacelike singularity of the Schwarzschild black hole can be
distinguished from the null and timelike naked singularity spacetimes. In light
of this, we investigate the precession of timelike bound orbits in the null
naked singularity spacetime, as well as tidal force effects and geodesic
deviation features. As a result, we find that the orbital precession of the
timelike bound orbits in null naked singularity spacetime could be
distinguished from the Schwarzschild precession case. The radial component of
the tidal force has an intriguing profile, whereas the angular component has a
profile which is comparable to that of a Schwarzschild black hole scenario. The
geodesic deviation equation is then solved numerically, yielding results that
resemble a Schwarzschild black hole. These characteristic features can then be
used to discern amongst these singularities.
| [
{
"created": "Mon, 31 Jan 2022 12:18:20 GMT",
"version": "v1"
},
{
"created": "Tue, 31 May 2022 09:17:44 GMT",
"version": "v2"
}
] | 2022-06-01 | [
[
"Madan",
"Siddharth",
""
],
[
"Bambhaniya",
"Parth",
""
]
] | Naked singularities form during the gravitational collapse of inhomogeneous matter clouds. The final nature of the singularity depends on the initial conditions of the matter properties and types of matter profiles. These naked singularities can also be divided into two types: null-like and timelike singularities. The spacelike singularity of the Schwarzschild black hole can be distinguished from the null and timelike naked singularity spacetimes. In light of this, we investigate the precession of timelike bound orbits in the null naked singularity spacetime, as well as tidal force effects and geodesic deviation features. As a result, we find that the orbital precession of the timelike bound orbits in null naked singularity spacetime could be distinguished from the Schwarzschild precession case. The radial component of the tidal force has an intriguing profile, whereas the angular component has a profile which is comparable to that of a Schwarzschild black hole scenario. The geodesic deviation equation is then solved numerically, yielding results that resemble a Schwarzschild black hole. These characteristic features can then be used to discern amongst these singularities. |
0907.1452 | Tigran Tchrakian | Eugen Radu, D. H. Tchrakian | Gravitating Yang--Mills fields in all dimensions | Presented to Heraeus School, Bremen, September 2008 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A classification of gravitating Yang--Mills systems in all dimensions is
presented. These systems are set up so that they support finite energy
solutions. Both regular and black hole solutions are considered, the former
being the limit of the latter for vanishing event horizon radius. Special
attention is paid to systems necessarily involving higher order Yang--Mills
curvature terms, along with the option of incorporating higher order terms in
the Riemann curvature. The scope here is restricted to Einstein systems, with
or without cosmological constant, and the Yang--Mills(--Higgs) systems.
| [
{
"created": "Thu, 9 Jul 2009 15:16:55 GMT",
"version": "v1"
}
] | 2009-07-10 | [
[
"Radu",
"Eugen",
""
],
[
"Tchrakian",
"D. H.",
""
]
] | A classification of gravitating Yang--Mills systems in all dimensions is presented. These systems are set up so that they support finite energy solutions. Both regular and black hole solutions are considered, the former being the limit of the latter for vanishing event horizon radius. Special attention is paid to systems necessarily involving higher order Yang--Mills curvature terms, along with the option of incorporating higher order terms in the Riemann curvature. The scope here is restricted to Einstein systems, with or without cosmological constant, and the Yang--Mills(--Higgs) systems. |
2310.00857 | P. A. Gonzalez | Ram\'on B\'ecar, P. A. Gonz\'alez, Eleftherios Papantonopoulos, Yerko
V\'asquez | Massive Scalar Field Perturbations of Black Holes Surrounded by Dark
Matter | Version accepted for publication in EPJC | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider scalar field perturbations in the background of black holes
immersed in perfect fluid dark matter (PFDM). We find, by using the sixth order
Wentzel-Kramers-Brillouin (WKB) approximation, that the longest-lived modes are
the ones with higher angular number, for a scalar field mass smaller than a
critical value, known as anomalous decay rate of the quasinormal modes, while
that beyond this critical value the behaviour is inverted. Moreover, we show
that it is possible to recover the real part of the quasinormal frequencies
(QNFs), the imaginary part of the QNFs, and the critical scalar field mass, of
the Schwarzschild background for different values of the PFDM intensity
parameter $k$, respectively. For values of $k$ smaller than these values, the
mentioned quantities are greater than the Schwarzschild background. However,
beyond of these values of $k$, these quantities are smaller than the
Schwarzschild background.
| [
{
"created": "Mon, 2 Oct 2023 02:39:31 GMT",
"version": "v1"
},
{
"created": "Mon, 4 Mar 2024 12:55:41 GMT",
"version": "v2"
}
] | 2024-03-05 | [
[
"Bécar",
"Ramón",
""
],
[
"González",
"P. A.",
""
],
[
"Papantonopoulos",
"Eleftherios",
""
],
[
"Vásquez",
"Yerko",
""
]
] | We consider scalar field perturbations in the background of black holes immersed in perfect fluid dark matter (PFDM). We find, by using the sixth order Wentzel-Kramers-Brillouin (WKB) approximation, that the longest-lived modes are the ones with higher angular number, for a scalar field mass smaller than a critical value, known as anomalous decay rate of the quasinormal modes, while that beyond this critical value the behaviour is inverted. Moreover, we show that it is possible to recover the real part of the quasinormal frequencies (QNFs), the imaginary part of the QNFs, and the critical scalar field mass, of the Schwarzschild background for different values of the PFDM intensity parameter $k$, respectively. For values of $k$ smaller than these values, the mentioned quantities are greater than the Schwarzschild background. However, beyond of these values of $k$, these quantities are smaller than the Schwarzschild background. |
1209.6088 | Peter Taylor | Peter Taylor | Self-force on an arbitrarily coupled static scalar particle in a
wormhole space-time | 6 pages, 1 figure, Significant changes/corrections made to previous
version | null | 10.1103/PhysRevD.87.024046 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we consider the problem of computing the self-force and
self-energy for a static scalar charge in a wormhole space-time with throat
profile $r(\rho)=\sqrt{\rho^{2}+a^{2}}$ for arbitrary coupling of the field to
the curvature. This calculation has previously been considered numerically by
Bezerra and Khusnutdinov, while analytic results have been obtained in the
special cases of minimal ($\xi=0$) coupling and conformal coupling ($\xi=1/8$
in three dimensions). We present here a closed form expression for the static
Green's function for arbitrary coupling and hence we obtain an analytic
expression for the self-force. The self-force depends crucially on the coupling
of the field to the curvature of the space-time and hence it is useful to
determine the dependence explicitly. The numerical computation can identify
some qualitative aspects of this dependence such as the change in the sign of
the force as it passes through the conformally coupled value, as well as the
fact that the self-force diverges for $\xi=1/2$. From the closed form
expression, it is straight-forward to see that there is an infinite set of
values of the coupling constant for which the self-force diverges, but we also
see that there is an infinite set of values for which the self-force vanishes.
| [
{
"created": "Wed, 26 Sep 2012 22:08:41 GMT",
"version": "v1"
},
{
"created": "Sat, 20 Oct 2012 22:51:36 GMT",
"version": "v2"
}
] | 2013-05-30 | [
[
"Taylor",
"Peter",
""
]
] | In this paper, we consider the problem of computing the self-force and self-energy for a static scalar charge in a wormhole space-time with throat profile $r(\rho)=\sqrt{\rho^{2}+a^{2}}$ for arbitrary coupling of the field to the curvature. This calculation has previously been considered numerically by Bezerra and Khusnutdinov, while analytic results have been obtained in the special cases of minimal ($\xi=0$) coupling and conformal coupling ($\xi=1/8$ in three dimensions). We present here a closed form expression for the static Green's function for arbitrary coupling and hence we obtain an analytic expression for the self-force. The self-force depends crucially on the coupling of the field to the curvature of the space-time and hence it is useful to determine the dependence explicitly. The numerical computation can identify some qualitative aspects of this dependence such as the change in the sign of the force as it passes through the conformally coupled value, as well as the fact that the self-force diverges for $\xi=1/2$. From the closed form expression, it is straight-forward to see that there is an infinite set of values of the coupling constant for which the self-force diverges, but we also see that there is an infinite set of values for which the self-force vanishes. |
1305.5896 | Giovanni Otalora | G. Otalora | Cosmological dynamics of tachyonic teleparallel dark energy | 14 pages, 1 figure. arXiv admin note: text overlap with
arXiv:1305.0474 | Phys. Rev. D 88, (2013) 063505 | 10.1103/PhysRevD.88.063505 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A detailed dynamical analysis of the tachyonic teleparallel dark energy
model, in which a non-canonical scalar field (tachyon field) is non-minimally
coupled to gravitation, is performed. It is found that, when the non-minimal
coupling is ruled by a dynamically changing coefficient $\alpha\equiv
f_{,\phi}/\sqrt{f}$, with $f(\phi)$ an arbitrary function of the scalar field
$\phi$, the universe may experience a field-matter-dominated era "$\phi$MDE",
in which it has some portions of the energy density of $\phi$ in the matter
dominated era. This is the most significant difference in relation to the
so-called teleparallel dark energy scenario, in which a canonical scalar field
(quintessence) is non-minimally coupled to gravitation.
| [
{
"created": "Sat, 25 May 2013 07:28:27 GMT",
"version": "v1"
},
{
"created": "Sat, 31 Aug 2013 00:57:10 GMT",
"version": "v2"
}
] | 2013-09-06 | [
[
"Otalora",
"G.",
""
]
] | A detailed dynamical analysis of the tachyonic teleparallel dark energy model, in which a non-canonical scalar field (tachyon field) is non-minimally coupled to gravitation, is performed. It is found that, when the non-minimal coupling is ruled by a dynamically changing coefficient $\alpha\equiv f_{,\phi}/\sqrt{f}$, with $f(\phi)$ an arbitrary function of the scalar field $\phi$, the universe may experience a field-matter-dominated era "$\phi$MDE", in which it has some portions of the energy density of $\phi$ in the matter dominated era. This is the most significant difference in relation to the so-called teleparallel dark energy scenario, in which a canonical scalar field (quintessence) is non-minimally coupled to gravitation. |
2304.12148 | Justin Janquart | Justin Janquart, K. Haris, Otto A. Hannuksela, Chris Van Den Broeck | The Return of GOLUM: Improving Distributed Joint Parameter Estimation
for Strongly-Lensed Gravitational Waves | 11 pages, 9 figures | null | 10.1093/mnras/stad2838 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Owing to the forecasted improved sensitivity of ground-based
gravitational-wave detectors, new research avenues will become accessible. This
is the case for gravitational-wave strong lensing, predicted with a
non-negligible observation rate in the coming years. However, because one needs
to investigate all the event pairs in the data, searches for strongly-lensed
gravitational waves are often computationally heavy, and one faces high
false-alarm rates. In this paper, we present upgrades made to the \GOLUM
software, making it more reliable while increasing its speed by re-casting the
look-up table, imposing a sample control, and implementing symmetric runs on
the two lensed images. We show how the recovered posteriors have improved
coverage of the parameter space and how we increase the pipeline's stability.
Finally, we show the results obtained by performing a joint analysis of all the
events reported until the GWTC-3 catalog, finding similar conclusions to the
ones presented in the literature.
| [
{
"created": "Mon, 24 Apr 2023 14:58:10 GMT",
"version": "v1"
}
] | 2023-10-18 | [
[
"Janquart",
"Justin",
""
],
[
"Haris",
"K.",
""
],
[
"Hannuksela",
"Otto A.",
""
],
[
"Broeck",
"Chris Van Den",
""
]
] | Owing to the forecasted improved sensitivity of ground-based gravitational-wave detectors, new research avenues will become accessible. This is the case for gravitational-wave strong lensing, predicted with a non-negligible observation rate in the coming years. However, because one needs to investigate all the event pairs in the data, searches for strongly-lensed gravitational waves are often computationally heavy, and one faces high false-alarm rates. In this paper, we present upgrades made to the \GOLUM software, making it more reliable while increasing its speed by re-casting the look-up table, imposing a sample control, and implementing symmetric runs on the two lensed images. We show how the recovered posteriors have improved coverage of the parameter space and how we increase the pipeline's stability. Finally, we show the results obtained by performing a joint analysis of all the events reported until the GWTC-3 catalog, finding similar conclusions to the ones presented in the literature. |
2002.12590 | Adrien Kuntz | Philippe Brax, Lavinia Heisenberg, Adrien Kuntz | Unveiling the Galileon in a three-body system : scalar and gravitational
wave production | 29 pages, 1 figure. Version accepted for publication in JCAP | null | 10.1088/1475-7516/2020/05/012 | null | gr-qc astro-ph.CO hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the prospect of detecting cubic Galileons through their imprint
on gravitational wave signals from a triple system. Namely, we consider a
massive Black Hole (BH) surrounded by a binary system of two smaller BHs. We
assume that the three BHs acquire a conformal coupling to the scalar field
whose origin could be due to cosmology or to the galactic environment. In this
case, the massive BH has a Vainshtein radius which englobes the smaller ones
and suppresses the scalar effects on the motion of the binary system. On the
other hand the two binaries can be outside each other's redressed Vainshtein
radius calculated in the background of the central BH, allowing for a
perturbative treatment of their dynamics. Despite the strong Vainshtein
suppression, we find that the scalar effects on the binary system are slightly
enhanced with respect to the static case and a significant amount of power can
be emitted in the form of the Galileon scalar field, hence actively
participating in the inspiralling phase. We compute the modification to the GW
phase and show that it can lead to a detectable signal for large enough
effective scalar coupling.
| [
{
"created": "Fri, 28 Feb 2020 08:13:49 GMT",
"version": "v1"
},
{
"created": "Fri, 1 May 2020 09:51:59 GMT",
"version": "v2"
}
] | 2020-05-07 | [
[
"Brax",
"Philippe",
""
],
[
"Heisenberg",
"Lavinia",
""
],
[
"Kuntz",
"Adrien",
""
]
] | We consider the prospect of detecting cubic Galileons through their imprint on gravitational wave signals from a triple system. Namely, we consider a massive Black Hole (BH) surrounded by a binary system of two smaller BHs. We assume that the three BHs acquire a conformal coupling to the scalar field whose origin could be due to cosmology or to the galactic environment. In this case, the massive BH has a Vainshtein radius which englobes the smaller ones and suppresses the scalar effects on the motion of the binary system. On the other hand the two binaries can be outside each other's redressed Vainshtein radius calculated in the background of the central BH, allowing for a perturbative treatment of their dynamics. Despite the strong Vainshtein suppression, we find that the scalar effects on the binary system are slightly enhanced with respect to the static case and a significant amount of power can be emitted in the form of the Galileon scalar field, hence actively participating in the inspiralling phase. We compute the modification to the GW phase and show that it can lead to a detectable signal for large enough effective scalar coupling. |
2407.11270 | Andrea Di Pinto | Andrea Di Pinto | Charged and Rotating Black Holes in a Melvin-swirling Universe | Master's thesis (Defended 09/07/2024, University of Milan -
Universit\`a degli Studi di Milano) | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | In this thesis, we present new exact solutions of Einstein-Maxwell's field
equations, with the most general case being the dyonic Kerr-Newman black hole
in a Melvin-swirling universe, obtained analytically using the Ehlers-Harrison
transformations of the Ernst formalism. Subsequently, for each possible
sub-case, we analyze the presence of singularities and study some physical
properties. Finally, we examine their supersymmetry in the context of $N=2$,
$d=4$ Supergravity.
| [
{
"created": "Mon, 15 Jul 2024 22:30:41 GMT",
"version": "v1"
}
] | 2024-07-17 | [
[
"Di Pinto",
"Andrea",
""
]
] | In this thesis, we present new exact solutions of Einstein-Maxwell's field equations, with the most general case being the dyonic Kerr-Newman black hole in a Melvin-swirling universe, obtained analytically using the Ehlers-Harrison transformations of the Ernst formalism. Subsequently, for each possible sub-case, we analyze the presence of singularities and study some physical properties. Finally, we examine their supersymmetry in the context of $N=2$, $d=4$ Supergravity. |
2009.03428 | Houri Ziaeepour | Houri Ziaeepour | Making a Quantum Universe: Symmetry and Gravity | 30 pages; No figure; v3: published version | Universe 2020, 6(11), 194 | 10.3390/universe6110194 | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | So far, none of attempts to quantize gravity has led to a satisfactory model
that not only describe gravity in the realm of a quantum world, but also its
relation to elementary particles and other fundamental forces. Here, we outline
the preliminary results for a model of quantum universe, in which gravity is
fundamentally and by construction quantic. The model is based on three well
motivated assumptions with compelling observational and theoretical evidence:
quantum mechanics is valid at all scales; quantum systems are described by
their symmetries; universe has infinite independent degrees of freedom. The
last assumption means that the Hilbert space of the Universe has
$SU(N\rightarrow \infty) \cong \text{area preserving Diff.} (S_2)$ symmetry,
which is parameterized by two angular variables. We show that, in the absence
of a background spacetime, this Universe is trivial and static. Nonetheless,
quantum fluctuations break the symmetry and divide the Universe to subsystems.
When a subsystem is singled out as reference -- observer -- and another as
clock, two more continuous parameters arise, which can be interpreted as
distance and time. We identify the classical spacetime with parameter space of
the Hilbert space of the Universe. Therefore, its quantization is meaningless.
In this view, the Einstein equation presents the projection of quantum dynamics
in the Hilbert space into its parameter space. Finite dimensional symmetries of
elementary particles emerge as a consequence of symmetry breaking when the
Universe is divided to subsystems/particles, without having any implication for
the infinite dimensional symmetry and its associated interaction - perceived as
gravity. This explains why gravity is a universal force.
| [
{
"created": "Mon, 7 Sep 2020 21:15:45 GMT",
"version": "v1"
},
{
"created": "Mon, 12 Oct 2020 19:38:04 GMT",
"version": "v2"
},
{
"created": "Thu, 25 Nov 2021 11:09:23 GMT",
"version": "v3"
}
] | 2021-11-29 | [
[
"Ziaeepour",
"Houri",
""
]
] | So far, none of attempts to quantize gravity has led to a satisfactory model that not only describe gravity in the realm of a quantum world, but also its relation to elementary particles and other fundamental forces. Here, we outline the preliminary results for a model of quantum universe, in which gravity is fundamentally and by construction quantic. The model is based on three well motivated assumptions with compelling observational and theoretical evidence: quantum mechanics is valid at all scales; quantum systems are described by their symmetries; universe has infinite independent degrees of freedom. The last assumption means that the Hilbert space of the Universe has $SU(N\rightarrow \infty) \cong \text{area preserving Diff.} (S_2)$ symmetry, which is parameterized by two angular variables. We show that, in the absence of a background spacetime, this Universe is trivial and static. Nonetheless, quantum fluctuations break the symmetry and divide the Universe to subsystems. When a subsystem is singled out as reference -- observer -- and another as clock, two more continuous parameters arise, which can be interpreted as distance and time. We identify the classical spacetime with parameter space of the Hilbert space of the Universe. Therefore, its quantization is meaningless. In this view, the Einstein equation presents the projection of quantum dynamics in the Hilbert space into its parameter space. Finite dimensional symmetries of elementary particles emerge as a consequence of symmetry breaking when the Universe is divided to subsystems/particles, without having any implication for the infinite dimensional symmetry and its associated interaction - perceived as gravity. This explains why gravity is a universal force. |
1610.06822 | David Delphenich | D. H. Delphenich | Line geometry and electromagnetism IV: electromagnetic fields as
infinitesimal Lorentz transformations | 33 pages, continuation of a series | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is first shown that the scalar product on any orthogonal space (V, g)
allows one to define linear isomorphisms of the vector spaces of bivectors and
2-forms on V with the underlying vector spaces of the Lie algebra so(p, q) and
its dual, respectively. When those isomorphisms are applied to the
electromagnetic excitation bivector and field strength 2-form, resp., one can
associate various algebraic constructions that pertain to them as bivector
fields and 2-forms with corresponding constructions in terms of so(1, 3) and
its dual. The subsequent association with corresponding things in line geometry
will then become straightforward. In particular, the fields can be represented
by motors, such as screws and wrenches, while the Cartan-Killing form on so(1,
3) is isometric to the scalar product on bivectors that gives the Klein
quadric. When the space of bivectors (and therefore the space of 2-forms) is
given an almost-complex structure (and therefore, a complex structure), one can
also represent most of the constructions on the former and its dual in terms of
so(3; C) and its dual.
| [
{
"created": "Fri, 21 Oct 2016 15:18:24 GMT",
"version": "v1"
}
] | 2016-10-24 | [
[
"Delphenich",
"D. H.",
""
]
] | It is first shown that the scalar product on any orthogonal space (V, g) allows one to define linear isomorphisms of the vector spaces of bivectors and 2-forms on V with the underlying vector spaces of the Lie algebra so(p, q) and its dual, respectively. When those isomorphisms are applied to the electromagnetic excitation bivector and field strength 2-form, resp., one can associate various algebraic constructions that pertain to them as bivector fields and 2-forms with corresponding constructions in terms of so(1, 3) and its dual. The subsequent association with corresponding things in line geometry will then become straightforward. In particular, the fields can be represented by motors, such as screws and wrenches, while the Cartan-Killing form on so(1, 3) is isometric to the scalar product on bivectors that gives the Klein quadric. When the space of bivectors (and therefore the space of 2-forms) is given an almost-complex structure (and therefore, a complex structure), one can also represent most of the constructions on the former and its dual in terms of so(3; C) and its dual. |
0812.2038 | Hideki Maeda | Hideki Maeda, Mokhtar Hassaine, and Cristian Martinez | Lovelock black holes with a nonlinear Maxwell field | 9 pages, no figure; v2, references added, published version in
Physical Review D | PhysRev.D79.044012,2009 | 10.1103/PhysRevD.79.044012 | CECS-PHY-08/20 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive electrically charged black hole solutions of the
Einstein-Gauss-Bonnet equations with a nonlinear electrodynamics source in $n
(\ge 5)$ dimensions. The spacetimes are given as a warped product $M^2 \times
K^{n-2}$, where $K^{n-2}$ is a $(n-2)$-dimensional constant curvature space. We
establish a generalized Birkhoff's theorem by showing that it is the unique
electrically charged solution with this isometry and for which the orbit of the
warp factor on $K^{n-2}$ is non-null. An extension of the analysis for full
Lovelock gravity is also achieved with a particular attention to the
Chern-Simons case.
| [
{
"created": "Wed, 10 Dec 2008 21:54:25 GMT",
"version": "v1"
},
{
"created": "Sat, 21 Feb 2009 23:52:56 GMT",
"version": "v2"
}
] | 2009-08-03 | [
[
"Maeda",
"Hideki",
""
],
[
"Hassaine",
"Mokhtar",
""
],
[
"Martinez",
"Cristian",
""
]
] | We derive electrically charged black hole solutions of the Einstein-Gauss-Bonnet equations with a nonlinear electrodynamics source in $n (\ge 5)$ dimensions. The spacetimes are given as a warped product $M^2 \times K^{n-2}$, where $K^{n-2}$ is a $(n-2)$-dimensional constant curvature space. We establish a generalized Birkhoff's theorem by showing that it is the unique electrically charged solution with this isometry and for which the orbit of the warp factor on $K^{n-2}$ is non-null. An extension of the analysis for full Lovelock gravity is also achieved with a particular attention to the Chern-Simons case. |
1808.07829 | Yen Chin Ong | B. Eslam Panah, S. H. Hendi, Y. C. Ong | Black Hole Remnant in Massive Gravity | version accepted for publication | Physics of the Dark Universe 27 (2020) 100452 | 10.1016/j.dark.2019.100452 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The possibility of a nonzero graviton mass has been widely pursued in the
literature. In this work we investigate a black hole solution in massive
gravity with a degenerate fiducial metric often used in the literature. We find
that the end state of Hawking evaporation leads to black hole remnant, which
could help to ameliorate the information paradox. We prove that these remnants
only exist in anti-de Sitter spacetime. Nevertheless, we speculate on their
possible relevance to our Universe as dark matter candidate, in view of the
possibility that our Universe could be inherently anti-de Sitter-like, with a
transient accelerated expansion phase.
| [
{
"created": "Thu, 23 Aug 2018 16:37:18 GMT",
"version": "v1"
},
{
"created": "Fri, 7 Dec 2018 16:10:54 GMT",
"version": "v2"
},
{
"created": "Mon, 6 Jan 2020 16:26:49 GMT",
"version": "v3"
}
] | 2020-01-07 | [
[
"Panah",
"B. Eslam",
""
],
[
"Hendi",
"S. H.",
""
],
[
"Ong",
"Y. C.",
""
]
] | The possibility of a nonzero graviton mass has been widely pursued in the literature. In this work we investigate a black hole solution in massive gravity with a degenerate fiducial metric often used in the literature. We find that the end state of Hawking evaporation leads to black hole remnant, which could help to ameliorate the information paradox. We prove that these remnants only exist in anti-de Sitter spacetime. Nevertheless, we speculate on their possible relevance to our Universe as dark matter candidate, in view of the possibility that our Universe could be inherently anti-de Sitter-like, with a transient accelerated expansion phase. |
gr-qc/0106023 | Naresh Dadhich | Naresh Dadhich | Nariai metric is the first example of the singularity free model | LaTeX, 3 pages | null | null | IUCAA-29/2001 | gr-qc astro-ph hep-th | null | This is just to point out that the Nariai metric is the first example of the
singularity free expanding perfect fluid cosmological model satisfying the weak
energy condition, $\rho>0, \rho+p=0$. It is a conformally non-flat Einstein
space.
| [
{
"created": "Thu, 7 Jun 2001 05:19:14 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Dadhich",
"Naresh",
""
]
] | This is just to point out that the Nariai metric is the first example of the singularity free expanding perfect fluid cosmological model satisfying the weak energy condition, $\rho>0, \rho+p=0$. It is a conformally non-flat Einstein space. |
1910.01699 | Rhiannon Cuttell | Rhiannon Cuttell | Deformed general relativity | Ph.D. thesis, King's College London. Submission date: Nov 2018. Award
date: Apr 2019. EThOS ID: uk.bl.ethos.784497. 128 pages, 10 figures. Text
overlap with arxiv:1409.1902, arxiv:1806.06791, arXiv:1812.07530, and
arxiv:1901.07383 | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this thesis, I investigate how to construct a self-consistent model of
deformed general relativity using canonical methods and metric variables. The
specific deformation of general covariance is predicted by some studies into
loop quantum cosmology. I firstly find the minimally-deformed model for a
scalar-tensor theory, thereby establishing a classical reference point, and
investigate the cosmological effects of a non-minimal coupled scalar field. By
treating the deformation perturbatively, I derive the deformed gravitational
action which includes the nearest order of curvature corrections. Then working
more generally, I derive the deformed scalar-tensor constraint to all orders
and I find that the momenta and spatial derivatives from gravity and matter
must combine in a very specific form. It suggests that the deformation should
be equally affected by matter field derivatives as it is by gravitational
curvature. Finally, I derive the deformed gravitational action to all orders,
and find how intrinsic and extrinsic curvatures differently affect the
deformation. The deformation seems to be required to satisfy a non-linear
equation usually found in fluid mechanics.
| [
{
"created": "Thu, 3 Oct 2019 19:35:20 GMT",
"version": "v1"
}
] | 2019-10-07 | [
[
"Cuttell",
"Rhiannon",
""
]
] | In this thesis, I investigate how to construct a self-consistent model of deformed general relativity using canonical methods and metric variables. The specific deformation of general covariance is predicted by some studies into loop quantum cosmology. I firstly find the minimally-deformed model for a scalar-tensor theory, thereby establishing a classical reference point, and investigate the cosmological effects of a non-minimal coupled scalar field. By treating the deformation perturbatively, I derive the deformed gravitational action which includes the nearest order of curvature corrections. Then working more generally, I derive the deformed scalar-tensor constraint to all orders and I find that the momenta and spatial derivatives from gravity and matter must combine in a very specific form. It suggests that the deformation should be equally affected by matter field derivatives as it is by gravitational curvature. Finally, I derive the deformed gravitational action to all orders, and find how intrinsic and extrinsic curvatures differently affect the deformation. The deformation seems to be required to satisfy a non-linear equation usually found in fluid mechanics. |
0811.4570 | Roberto Giambo' | Roberto Giamb\`o | Gravitational collapse of homogeneous perfect fluid in HOG theories | LaTeX2e, 13 pages, 10 figures, to appear on J. Math. Phys | J. Math. Phys. 50:012501,2009 | 10.1063/1.3032755 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper investigates the evolution of collapsing FRW models with a scalar
field having the potential which arises in the conformal frame of high order
gravity theories, coupled to matter described by a perfect fluid with energy
density $\rho$ and pressure $p$, obeying a barotropic equation of state. The
solutions are shown to evolve generically to a singular state in a finite time
and they are used as sources for radiating objects undergoing complete
gravitational collapse. Although these singularities may be naked in some
special case, it is shown that generically a black hole forms.
| [
{
"created": "Thu, 27 Nov 2008 15:50:06 GMT",
"version": "v1"
}
] | 2010-03-24 | [
[
"Giambò",
"Roberto",
""
]
] | This paper investigates the evolution of collapsing FRW models with a scalar field having the potential which arises in the conformal frame of high order gravity theories, coupled to matter described by a perfect fluid with energy density $\rho$ and pressure $p$, obeying a barotropic equation of state. The solutions are shown to evolve generically to a singular state in a finite time and they are used as sources for radiating objects undergoing complete gravitational collapse. Although these singularities may be naked in some special case, it is shown that generically a black hole forms. |
gr-qc/9404058 | null | Bj{\o}rn Jensen | Aspects of the Thermo-Dynamics of a Black Hole with a Topological Defect | 13, Oslo-TP-5-94, misprints corrected, to appear in Phys.Lett.B | Phys.Lett.B334:309-314,1994 | 10.1016/0370-2693(94)90694-7 | null | gr-qc | null | Aspects of the thermo-dynamics of a black hole which is either pierced by a
cosmic gauge string or contains a global monopole are investigated. We also
make some comments on the physical significance of the fact that the
gravitational mass carried by a global monopole is negative. We note in
particular that the negative monopole mass implies a gravitational
super-radiance effect.
| [
{
"created": "Thu, 28 Apr 1994 16:14:38 GMT",
"version": "v1"
},
{
"created": "Tue, 21 Jun 1994 13:43:06 GMT",
"version": "v2"
}
] | 2010-11-01 | [
[
"Jensen",
"Bjørn",
""
]
] | Aspects of the thermo-dynamics of a black hole which is either pierced by a cosmic gauge string or contains a global monopole are investigated. We also make some comments on the physical significance of the fact that the gravitational mass carried by a global monopole is negative. We note in particular that the negative monopole mass implies a gravitational super-radiance effect. |
gr-qc/9501035 | Ralf Hecht | Ralf. D Hecht | Mass and Spin of Poincare Gauge Theory | 16 pages, plain-tex; to be published in Gen. Rel. Grav | Gen.Rel.Grav. 27 (1995) 537-554 | 10.1007/BF02105078 | null | gr-qc | null | We discuss two expressions for the conserved quantities (energy momentum and
angular momentum) of the Poincar\'e Gauge Theory. We show, that the variations
of the Hamiltonians, of which the expressions are the respective boundary
terms, are well defined, if we choose an appropriate phase space for asymptotic
flat gravitating systems. Furthermore, we compare the expressions with others,
known from the literature.
| [
{
"created": "Thu, 26 Jan 1995 17:55:09 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Hecht",
"Ralf. D",
""
]
] | We discuss two expressions for the conserved quantities (energy momentum and angular momentum) of the Poincar\'e Gauge Theory. We show, that the variations of the Hamiltonians, of which the expressions are the respective boundary terms, are well defined, if we choose an appropriate phase space for asymptotic flat gravitating systems. Furthermore, we compare the expressions with others, known from the literature. |
1910.12660 | Maria Churilova | M. S. Churilova and Z. Stuchlik | Quasinormal modes of black holes in 5D Gauss-Bonnet gravity combined
with non-linear electrodynamics | 10 pages, 9 figures, revtex4-1 | Annals of Physics 418 (2020) 168181 | 10.1016/j.aop.2020.168181 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Quasinormal modes of black holes were previously calculated in a non-linear
electrodynamics and in the Gauss-Bonnet gravity theory. Here we take into
consideration both of the above factors and find quasinormal modes of a
(massive) scalar field in the background of a black hole in the
five-dimensional Einstein-Gauss-Bonnet gravity coupled to a non-linear
electrodynamics having Maxwellian weak-field limit. For the non-linear
electrodynamics we considered the high frequency (eikonal) regime of
oscillations analytically, while for the lower multipoles the higher order WKB
analysis with the help of Pad\'{e} approximants and the time domain integration
were used. We found that perturbations of a test scalar field violate the
inequality between the damping rate of the least damped mode and the Hawking
temperature, known as the Hod's proposal. This does not exclude the situation
in which gravitational spectrum may restore the Hod's inequality, so that only
the analysis of the full spectrum, including gravitational perturbations, will
show if the quasinormal modes we found here for the scalar field can be a
counterexample to the Hod's conjecture or not. We also revealed that in such a
system, which includes the higher curvature corrections and non-linear
electrodynamics, for perturbations of a massive scalar field there exists the
phenomenon of the arbitrary long lived quasinormal modes - quasiresonances.
| [
{
"created": "Mon, 28 Oct 2019 13:24:59 GMT",
"version": "v1"
},
{
"created": "Mon, 23 Dec 2019 09:33:47 GMT",
"version": "v2"
},
{
"created": "Fri, 1 May 2020 12:51:41 GMT",
"version": "v3"
}
] | 2020-05-04 | [
[
"Churilova",
"M. S.",
""
],
[
"Stuchlik",
"Z.",
""
]
] | Quasinormal modes of black holes were previously calculated in a non-linear electrodynamics and in the Gauss-Bonnet gravity theory. Here we take into consideration both of the above factors and find quasinormal modes of a (massive) scalar field in the background of a black hole in the five-dimensional Einstein-Gauss-Bonnet gravity coupled to a non-linear electrodynamics having Maxwellian weak-field limit. For the non-linear electrodynamics we considered the high frequency (eikonal) regime of oscillations analytically, while for the lower multipoles the higher order WKB analysis with the help of Pad\'{e} approximants and the time domain integration were used. We found that perturbations of a test scalar field violate the inequality between the damping rate of the least damped mode and the Hawking temperature, known as the Hod's proposal. This does not exclude the situation in which gravitational spectrum may restore the Hod's inequality, so that only the analysis of the full spectrum, including gravitational perturbations, will show if the quasinormal modes we found here for the scalar field can be a counterexample to the Hod's conjecture or not. We also revealed that in such a system, which includes the higher curvature corrections and non-linear electrodynamics, for perturbations of a massive scalar field there exists the phenomenon of the arbitrary long lived quasinormal modes - quasiresonances. |
gr-qc/9304002 | null | Nguyen Hong Chuong, and Nguyen Van Hoang | Bianchi Cosmological Models in the Minimum Quadratic Poincare Gauge
Theory of Gravity | REVTEX, 17 pages, Syracuse University preprint SU-GP-93/3-4 | null | null | null | gr-qc astro-ph | null | Within the framework of the minimum quadratic Poincare gauge theory of
gravity in the Riemann-Cartan spacetime the dynamics of homogeneous anisotropic
Bianchi types I-IX spinning-fluid cosmological models is investigated. A basic
equation set for these models is obtained and analyzed. In particular, exact
solutions for the Bianchi type-I spinning-fluid and Bianchi type-V
perfect-fluid models are found in analytic form.
| [
{
"created": "Thu, 1 Apr 1993 19:14:00 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Chuong",
"Nguyen Hong",
""
],
[
"Van Hoang",
"Nguyen",
""
]
] | Within the framework of the minimum quadratic Poincare gauge theory of gravity in the Riemann-Cartan spacetime the dynamics of homogeneous anisotropic Bianchi types I-IX spinning-fluid cosmological models is investigated. A basic equation set for these models is obtained and analyzed. In particular, exact solutions for the Bianchi type-I spinning-fluid and Bianchi type-V perfect-fluid models are found in analytic form. |
gr-qc/9412025 | Takahiro Tanaka | Misao Sasaki, Takahiro Tanaka and Kazuhiro Yamamoto | Euclidian Vacuum Mode Functions for a Scalar Field on Open De Sitter
Spacetime | 18 pages, revtex file, 3 uuencoded compressed postscript figures
appended at the end | Phys.Rev.D51:2979-2995,1995 | 10.1103/PhysRevD.51.2979 | KUNS 1308 | gr-qc | null | Motivated by recent studies of the one-bubble inflationary universe scenario
that predicts a low density, negative curvature universe, we investigate the
Euclidean vacuum mode functions of a scalar field in a spatially open chart of
de Sitter space which is foliated by hyperbolic time slices. When we consider
the possibility of an open inflationary universe, we are faced with the problem
of the initial condition for the quantum fluctuations of the inflaton field,
because the inflationary era should not last too long to lose every information
of the initial condition. In the one-bubble scenario in which an open universe
is created in an exponentially expanding false vacuum universe triggered by
quantum decay of false vacuum, it seems natural that the initial state is the
de Sitter-invariant Euclidean vacuum. Here we present explicit expressions for
the Euclidean vacuum mode functions in the open chart for a scalar field with
arbitrary mass and curvature coupling.
| [
{
"created": "Thu, 8 Dec 1994 15:36:29 GMT",
"version": "v1"
}
] | 2009-10-09 | [
[
"Sasaki",
"Misao",
""
],
[
"Tanaka",
"Takahiro",
""
],
[
"Yamamoto",
"Kazuhiro",
""
]
] | Motivated by recent studies of the one-bubble inflationary universe scenario that predicts a low density, negative curvature universe, we investigate the Euclidean vacuum mode functions of a scalar field in a spatially open chart of de Sitter space which is foliated by hyperbolic time slices. When we consider the possibility of an open inflationary universe, we are faced with the problem of the initial condition for the quantum fluctuations of the inflaton field, because the inflationary era should not last too long to lose every information of the initial condition. In the one-bubble scenario in which an open universe is created in an exponentially expanding false vacuum universe triggered by quantum decay of false vacuum, it seems natural that the initial state is the de Sitter-invariant Euclidean vacuum. Here we present explicit expressions for the Euclidean vacuum mode functions in the open chart for a scalar field with arbitrary mass and curvature coupling. |
0803.0905 | Woei Chet Lim | A. A. Coley, W. C. Lim, G. Leon | Spherically symmetric cosmology: resource paper | 14 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We use the 1+3 frame formalism to write down the evolution equations for
spherically symmetric models as a well-posed system of first order PDEs in two
variables, suitable for numerical and qualitative analysis.
| [
{
"created": "Thu, 6 Mar 2008 16:39:49 GMT",
"version": "v1"
}
] | 2008-03-07 | [
[
"Coley",
"A. A.",
""
],
[
"Lim",
"W. C.",
""
],
[
"Leon",
"G.",
""
]
] | We use the 1+3 frame formalism to write down the evolution equations for spherically symmetric models as a well-posed system of first order PDEs in two variables, suitable for numerical and qualitative analysis. |
2009.01932 | Jesus Buitrago | J. Buitrago | Unified Picture of Electromagnetic and Gravitational Forces in
Two-Spinor Language | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The well known Geodesic Equation of General Relativity is newly formulated in
Weyl two-spinor language in a convenient way susceptible of being combined with
a set of two-spinor equations, equivalent to the Lorentz Force of
Electrodynamics, obtained in previous studies. General spinor equations of
motion for a test charged spin 1/2 particle in arbitrary electromagnetic and
gravitational fields fields are obtained describing not only spacetime
trajectories but also spin precession. For the case of the Schwarzschild metric
and radial trajectories, spinor equations unifying gravitational and electric
forces are obtained and solved for a weak gravitational field (or long distance
from the source).
| [
{
"created": "Thu, 3 Sep 2020 21:25:31 GMT",
"version": "v1"
}
] | 2020-09-07 | [
[
"Buitrago",
"J.",
""
]
] | The well known Geodesic Equation of General Relativity is newly formulated in Weyl two-spinor language in a convenient way susceptible of being combined with a set of two-spinor equations, equivalent to the Lorentz Force of Electrodynamics, obtained in previous studies. General spinor equations of motion for a test charged spin 1/2 particle in arbitrary electromagnetic and gravitational fields fields are obtained describing not only spacetime trajectories but also spin precession. For the case of the Schwarzschild metric and radial trajectories, spinor equations unifying gravitational and electric forces are obtained and solved for a weak gravitational field (or long distance from the source). |
gr-qc/9701015 | Serge Massar | S. Massar and R. Parentani | Gravitational Instanton for Black Hole Radiation | 10 pages, latex | Phys.Rev.Lett. 78 (1997) 3810-3813 | 10.1103/PhysRevLett.78.3810 | TAUP2403-97 | gr-qc | null | Hawking radiation is derived from the existence of a euclidean instanton
which lives in the euclidean black hole geometry. Upon taking into account the
gravitational field of the instanton itself, its action is exactly equal to one
quarter the change in the horizon area. This result also applies to the
Schwinger process, the Unruh process, and particle creation in deSitter space.
The implications for horizon thermodynamics are discussed.
| [
{
"created": "Fri, 10 Jan 1997 08:01:22 GMT",
"version": "v1"
}
] | 2009-10-30 | [
[
"Massar",
"S.",
""
],
[
"Parentani",
"R.",
""
]
] | Hawking radiation is derived from the existence of a euclidean instanton which lives in the euclidean black hole geometry. Upon taking into account the gravitational field of the instanton itself, its action is exactly equal to one quarter the change in the horizon area. This result also applies to the Schwinger process, the Unruh process, and particle creation in deSitter space. The implications for horizon thermodynamics are discussed. |
1208.0168 | Stephen Casey Mr | Stephen Casey | Optical 2-metrics of Schwarzschild-Tangherlini Spacetimes and the
Bohlin-Arnold Duality | 10 pages | null | 10.1088/0264-9381/29/23/237001 | DAMTP-2012-55 | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the projection of null geodesics of the Schwarzschild-Tangherlini
metric in n+1 dimensions to the space of orbits of the static Killing vector
where the motion of a given light ray is seen to lie in a plane. The projected
curves coincide with the unparametrised geodesics of optical 2-metrics and can
be equally understood as describing the motion of a non-relativistic particle
in a central force. We consider a duality between the projected null curves for
pairs of values of n and interpret its mathematical meaning in terms of the
optical 2-metrics. The metrics are not projectively equivalent but the
correspondence can be exposed in terms of a third order differential equation.
We also explore the extension of this notion of duality to the
Reissner-Nordstrom case.
| [
{
"created": "Wed, 1 Aug 2012 10:39:19 GMT",
"version": "v1"
}
] | 2015-06-11 | [
[
"Casey",
"Stephen",
""
]
] | We consider the projection of null geodesics of the Schwarzschild-Tangherlini metric in n+1 dimensions to the space of orbits of the static Killing vector where the motion of a given light ray is seen to lie in a plane. The projected curves coincide with the unparametrised geodesics of optical 2-metrics and can be equally understood as describing the motion of a non-relativistic particle in a central force. We consider a duality between the projected null curves for pairs of values of n and interpret its mathematical meaning in terms of the optical 2-metrics. The metrics are not projectively equivalent but the correspondence can be exposed in terms of a third order differential equation. We also explore the extension of this notion of duality to the Reissner-Nordstrom case. |
1003.0239 | Bruno Coutinho Mundim | Bruno C. Mundim | A Numerical Study of Boson Star Binaries | 184 pages, 47 figures, PhD thesis (University of British Columbia) | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This thesis describes a numerical study of binary boson stars within the
context of an approximation to general relativity. The approximation we adopt
places certain restrictions on the dynamical variables of general relativity
(conformal flatness of the 3-metric), and on the time-slicing of the spacetime
(maximal slicing). The resulting modeling problem requires the solution of a
coupled nonlinear system of 4 hyperbolic, and 5 elliptic partial differential
equations (PDEs) in three space dimensions and time. We approximately solve
this system as an initial-boundary value problem, using finite difference
techniques and well known, computationally efficient numerical algorithms such
as the multigrid method in the case of the elliptic equations. Careful
attention is paid to the issue of code validation, and a key part of the thesis
is the demonstration that, as the basic scale of finite difference
discretization is reduced, our numerical code generates results that converge
to a solution of the continuum system of PDEs as desired. The thesis concludes
with a discussion of results from some initial explorations of the orbital
dynamics of boson star binaries. In particular, we describe calculations in
which motion of such a binary is followed for more than two orbital periods,
which is a significant advance over previous studies. We also present results
from computations in which the boson stars merge, and where there is evidence
for black hole formation.
| [
{
"created": "Mon, 1 Mar 2010 03:02:26 GMT",
"version": "v1"
}
] | 2010-03-02 | [
[
"Mundim",
"Bruno C.",
""
]
] | This thesis describes a numerical study of binary boson stars within the context of an approximation to general relativity. The approximation we adopt places certain restrictions on the dynamical variables of general relativity (conformal flatness of the 3-metric), and on the time-slicing of the spacetime (maximal slicing). The resulting modeling problem requires the solution of a coupled nonlinear system of 4 hyperbolic, and 5 elliptic partial differential equations (PDEs) in three space dimensions and time. We approximately solve this system as an initial-boundary value problem, using finite difference techniques and well known, computationally efficient numerical algorithms such as the multigrid method in the case of the elliptic equations. Careful attention is paid to the issue of code validation, and a key part of the thesis is the demonstration that, as the basic scale of finite difference discretization is reduced, our numerical code generates results that converge to a solution of the continuum system of PDEs as desired. The thesis concludes with a discussion of results from some initial explorations of the orbital dynamics of boson star binaries. In particular, we describe calculations in which motion of such a binary is followed for more than two orbital periods, which is a significant advance over previous studies. We also present results from computations in which the boson stars merge, and where there is evidence for black hole formation. |
2202.05092 | Rui Niu | Rui Niu, Tao Zhu, Wen Zhao | Testing Lorentz Invariance of Gravity in the Standard Model Extension
with GWTC-3 | 29 pages, 6 figures | null | 10.1088/1475-7516/2022/12/011 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Successful detection of gravitational waves has presented a new avenue to
explore the nature of gravity. With the cumulative catalog of detected events,
we can perform tests on General Relativity from various aspects with increasing
precision. In this work, we focus on Lorentz symmetry during propagation of
gravitational waves. Considering the dispersion relation in the gauge-invariant
linearized gravity sector of the Standard-Model Extension, the anisotropy,
birefringence, and dispersion effects will be induced during propagation of
gravitational waves because of the Lorentz violating modification, and cause
dephasings in waveform received by detectors. With the distorted waveform, we
perform full Bayesian inference with confident events in the last gravitational
wave catalog. We consider two cases associated with the lowest mass dimension
$d=5,6$ which are supposed to have the most significant effects, and place the
constraints on the expansion coefficients characterizing the Lorentz violating
behavior which have 16 independent components for $d=5$ and 18 components for
$d=6$. We do not find any evidence for Lorentz violation in the gravitational
wave data, the constraints on the coefficients are on the order of
$10^{-15}{\rm m}$ for $d=5$ and $10^{-10}{\rm m^2}$ for $d=6$ respectively.
| [
{
"created": "Thu, 10 Feb 2022 15:30:03 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Mar 2023 15:10:20 GMT",
"version": "v2"
}
] | 2023-03-07 | [
[
"Niu",
"Rui",
""
],
[
"Zhu",
"Tao",
""
],
[
"Zhao",
"Wen",
""
]
] | Successful detection of gravitational waves has presented a new avenue to explore the nature of gravity. With the cumulative catalog of detected events, we can perform tests on General Relativity from various aspects with increasing precision. In this work, we focus on Lorentz symmetry during propagation of gravitational waves. Considering the dispersion relation in the gauge-invariant linearized gravity sector of the Standard-Model Extension, the anisotropy, birefringence, and dispersion effects will be induced during propagation of gravitational waves because of the Lorentz violating modification, and cause dephasings in waveform received by detectors. With the distorted waveform, we perform full Bayesian inference with confident events in the last gravitational wave catalog. We consider two cases associated with the lowest mass dimension $d=5,6$ which are supposed to have the most significant effects, and place the constraints on the expansion coefficients characterizing the Lorentz violating behavior which have 16 independent components for $d=5$ and 18 components for $d=6$. We do not find any evidence for Lorentz violation in the gravitational wave data, the constraints on the coefficients are on the order of $10^{-15}{\rm m}$ for $d=5$ and $10^{-10}{\rm m^2}$ for $d=6$ respectively. |
gr-qc/0409007 | Serguei Krasnikov | S. Krasnikov | Counter example to a quantum inequality | Sec. II is completely rewritten: the gulf is discussed between the
proven QIs and those used in ruling out exotic spacetimes | Grav.Cosmol. 46 (2006) 195 | null | null | gr-qc | null | A `quantum inequality' (a conjectured relation between the energy density of
a free quantum field and the time during which this density is observed) has
recently been used to rule out some of the macroscopic wormholes and warp
drives. I discuss the possibility of generalizing that result to other similar
spacetimes and first show that the problem amounts to verification of a
slightly different inequality. This new inequality \emph{can} replace the
original one, if an additional assumption (concerning homogeneity of the
`exotic matter' distribution) is made, and \emph{must} replace it if the
assumption is relaxed. Then by an explicit example I show that the `new'
inequality breaks down even in a simplest case (a free field in a simply
connected two dimensional space). Which suggests that there is no grounds today
to consider such spacetimes `unphysical'.
| [
{
"created": "Wed, 1 Sep 2004 16:27:59 GMT",
"version": "v1"
},
{
"created": "Tue, 12 Oct 2004 11:22:58 GMT",
"version": "v2"
},
{
"created": "Wed, 25 May 2005 20:35:51 GMT",
"version": "v3"
}
] | 2007-05-23 | [
[
"Krasnikov",
"S.",
""
]
] | A `quantum inequality' (a conjectured relation between the energy density of a free quantum field and the time during which this density is observed) has recently been used to rule out some of the macroscopic wormholes and warp drives. I discuss the possibility of generalizing that result to other similar spacetimes and first show that the problem amounts to verification of a slightly different inequality. This new inequality \emph{can} replace the original one, if an additional assumption (concerning homogeneity of the `exotic matter' distribution) is made, and \emph{must} replace it if the assumption is relaxed. Then by an explicit example I show that the `new' inequality breaks down even in a simplest case (a free field in a simply connected two dimensional space). Which suggests that there is no grounds today to consider such spacetimes `unphysical'. |
gr-qc/0108074 | Jose Antonio Belinchon | J. A. Belinchon, T. Harko, M. K. Mak | Renormalization Group Approach to Causal Viscous Cosmological Models | 19 pages. RevTeX4. Revised version. Accepted in Classical and Quantum
Gravity | Class.Quant.Grav.19:3003-3015,2002 | 10.1088/0264-9381/19/11/316 | null | gr-qc | null | The renormalization group method is applied to the study of homogeneous and
flat Friedmann-Robertson-Walker type Universes, filled with a causal bulk
viscous cosmological fluid. The starting point of the study is the
consideration of the scaling properties of the gravitational field equations,
of the causal evolution equation of the bulk viscous pressure and of the
equations of state. The requirement of scale invariance imposes strong
constraints on the temporal evolution of the bulk viscosity coefficient,
temperature and relaxation time, thus leading to the possibility of obtaining
the bulk viscosity coefficient-energy density dependence. For a cosmological
model with bulk viscosity coefficient proportional to the Hubble parameter, we
perform the analysis of the renormalization group flow around the scale
invariant fixed point, therefore obtaining the long time behavior of the scale
factor.
| [
{
"created": "Wed, 29 Aug 2001 09:26:12 GMT",
"version": "v1"
},
{
"created": "Wed, 24 Apr 2002 05:28:28 GMT",
"version": "v2"
}
] | 2009-09-25 | [
[
"Belinchon",
"J. A.",
""
],
[
"Harko",
"T.",
""
],
[
"Mak",
"M. K.",
""
]
] | The renormalization group method is applied to the study of homogeneous and flat Friedmann-Robertson-Walker type Universes, filled with a causal bulk viscous cosmological fluid. The starting point of the study is the consideration of the scaling properties of the gravitational field equations, of the causal evolution equation of the bulk viscous pressure and of the equations of state. The requirement of scale invariance imposes strong constraints on the temporal evolution of the bulk viscosity coefficient, temperature and relaxation time, thus leading to the possibility of obtaining the bulk viscosity coefficient-energy density dependence. For a cosmological model with bulk viscosity coefficient proportional to the Hubble parameter, we perform the analysis of the renormalization group flow around the scale invariant fixed point, therefore obtaining the long time behavior of the scale factor. |
0803.2899 | Maximiliano Ujevic | Jose D. Polanco, Patricio S. Letelier and Maximiliano Ujevic | Static charged fluid around a massive magnetic dipole | 7 pages, 1 figure, revtex. A discussion on frame dragging added.
Accepted in PRD | Phys.Rev.D78:024026,2008 | 10.1103/PhysRevD.78.024026 | null | gr-qc astro-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An analytical solution of Einstein-Maxwell equations with a static fluid as a
source is presented. The spacetime is represented by the axially symmetric Weyl
metric and the energy-momentum tensor describes a coupling of a fluid with an
electromagnetic field. When appropriate limits are performed we recover the
well-known solutions of Gutsunaev-Manko and Schwarzschild. Also, using Eckart's
thermodynamics, we calculated the temperature, the mechanical pressure, the
charge density and the energy density of the system. The analysis of
thermodynamic quantities suggests that the solution can be used to represent a
magnetized compact stellar object surrounded by a charged fluid.
| [
{
"created": "Wed, 19 Mar 2008 21:35:13 GMT",
"version": "v1"
},
{
"created": "Tue, 20 May 2008 02:08:27 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Polanco",
"Jose D.",
""
],
[
"Letelier",
"Patricio S.",
""
],
[
"Ujevic",
"Maximiliano",
""
]
] | An analytical solution of Einstein-Maxwell equations with a static fluid as a source is presented. The spacetime is represented by the axially symmetric Weyl metric and the energy-momentum tensor describes a coupling of a fluid with an electromagnetic field. When appropriate limits are performed we recover the well-known solutions of Gutsunaev-Manko and Schwarzschild. Also, using Eckart's thermodynamics, we calculated the temperature, the mechanical pressure, the charge density and the energy density of the system. The analysis of thermodynamic quantities suggests that the solution can be used to represent a magnetized compact stellar object surrounded by a charged fluid. |
2304.10015 | Xi-Jing Wang | Xi-Jing Wang, Xiao-Mei Kuang, Yuan Meng, Bin Wang, Jian-Pin Wu | Rings and images of Horndeski hairy black hole illuminated by various
thin accretions | 21 pages, 13 figures, matching the version published in PRD | Phys. Rev. D 107, 124052 (2023) | 10.1103/PhysRevD.107.124052 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We analyze the light rays around a static hairy black hole in Horndeski
gravity with the use of ray-tracing procedure. We find that a stronger
Horndeski hairy parameter corresponds to larger photon sphere as well as
critical impact parameter, and wider ranges of photon ring and lensed ring
emissions. These influences can be robustly interpreted from the shape of the
effective potential of the photon's radial motion. Based on the distribution of
the light rays, we then investigate the optical appearances of the Horndeski
hairy black hole surrounded by various thin accretions. Firstly, we consider
that the Horndeski hairy black hole is illuminated by the optically and
geometrically thin accretion disk. We carefully clarify the contributions from
the direct, lensed ring and photon ring intensities to the total observed
intensity via the transfer function, which is rarely discussed in this
scenario. We find that the Horndeski hair has significant influences on both
shadow size and distributions of direct, lensed ring and photon ring brightness
in three standard emission profiles. As a result, the rings and images of
Horndeski hairy black hole and the origination of their brightness
differentiate from those of Schwarzschild black hole (SBH). Then, when the
Horndeski hairy black hole is illuminated by thin spherical accretions, the
hairy black hole's shadow surrounded by a bright ring is larger than that of
SBH, but the brightness of ring is fainter. Similar to that of SBH, the size of
hairy black hole shadow does not change as the radial moving of the spherical
accretion, and the brightness for the infalling accretion is fainter than that
for the static accretion due to the Doppler effect. Therefore, we argue that
the black hole image consisting of the shadow and accretion construction could,
in theory, reflect the observational differences between the Horndeski hairy
black hole and SBH.
| [
{
"created": "Wed, 19 Apr 2023 23:57:49 GMT",
"version": "v1"
},
{
"created": "Mon, 19 Jun 2023 09:04:04 GMT",
"version": "v2"
},
{
"created": "Thu, 29 Jun 2023 13:22:57 GMT",
"version": "v3"
}
] | 2023-06-30 | [
[
"Wang",
"Xi-Jing",
""
],
[
"Kuang",
"Xiao-Mei",
""
],
[
"Meng",
"Yuan",
""
],
[
"Wang",
"Bin",
""
],
[
"Wu",
"Jian-Pin",
""
]
] | We analyze the light rays around a static hairy black hole in Horndeski gravity with the use of ray-tracing procedure. We find that a stronger Horndeski hairy parameter corresponds to larger photon sphere as well as critical impact parameter, and wider ranges of photon ring and lensed ring emissions. These influences can be robustly interpreted from the shape of the effective potential of the photon's radial motion. Based on the distribution of the light rays, we then investigate the optical appearances of the Horndeski hairy black hole surrounded by various thin accretions. Firstly, we consider that the Horndeski hairy black hole is illuminated by the optically and geometrically thin accretion disk. We carefully clarify the contributions from the direct, lensed ring and photon ring intensities to the total observed intensity via the transfer function, which is rarely discussed in this scenario. We find that the Horndeski hair has significant influences on both shadow size and distributions of direct, lensed ring and photon ring brightness in three standard emission profiles. As a result, the rings and images of Horndeski hairy black hole and the origination of their brightness differentiate from those of Schwarzschild black hole (SBH). Then, when the Horndeski hairy black hole is illuminated by thin spherical accretions, the hairy black hole's shadow surrounded by a bright ring is larger than that of SBH, but the brightness of ring is fainter. Similar to that of SBH, the size of hairy black hole shadow does not change as the radial moving of the spherical accretion, and the brightness for the infalling accretion is fainter than that for the static accretion due to the Doppler effect. Therefore, we argue that the black hole image consisting of the shadow and accretion construction could, in theory, reflect the observational differences between the Horndeski hairy black hole and SBH. |
2405.13552 | Alexey Dubinsky | Alexey Dubinsky | Quantum gravitational corrections to the Schwarzschild spacetime and
quasinormal frequencies | arXiv admin note: text overlap with arXiv:2405.06390 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Quantum gravitational corrections to the entropy of the Schwarzschild black
hole, derived using the Wald entropy formula within an effective field theory
framework, were presented in [X. Calmet, F. Kuipers Phys.Rev.D 104 (2021) 6,
066012]. These corrections result in a Schwarzschild spacetime that is deformed
by the quantum correction. However, it is observed that the proposed
quantum-corrected metric describes not a black hole but a wormhole.
Nevertheless, further expansion of the metric function in terms of the quantum
correction parameter yields a well-defined black hole metric whose geometry
closely resembles that of a wormhole. We also explore methods for
distinguishing between these quantum-corrected spacetimes based on the
quasinormal frequencies they emit.
| [
{
"created": "Wed, 22 May 2024 11:40:05 GMT",
"version": "v1"
}
] | 2024-05-24 | [
[
"Dubinsky",
"Alexey",
""
]
] | Quantum gravitational corrections to the entropy of the Schwarzschild black hole, derived using the Wald entropy formula within an effective field theory framework, were presented in [X. Calmet, F. Kuipers Phys.Rev.D 104 (2021) 6, 066012]. These corrections result in a Schwarzschild spacetime that is deformed by the quantum correction. However, it is observed that the proposed quantum-corrected metric describes not a black hole but a wormhole. Nevertheless, further expansion of the metric function in terms of the quantum correction parameter yields a well-defined black hole metric whose geometry closely resembles that of a wormhole. We also explore methods for distinguishing between these quantum-corrected spacetimes based on the quasinormal frequencies they emit. |
1611.01614 | Deng Wang | Deng Wang | Wormholes in a viscous universe | 14 pages, 3 figs, accepted in Physics of the Dark Universe | Phys.Dark Univ. 35 (2022) 100944 | 10.1016/j.dark.2021.100944 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the static and spherically symmetric wormhole spacetime
configurations at present time in a viscous universe. Considering three classes
of viscous models, i.e., bulk viscosity as a function of Hubble constant $H_0$,
present cosmic temperature $T_0$ and dark energy density $\rho_0$,
respectively, we obtain several wormhole solutions. Through the analysis for
the anisotropic solutions, we conclude that, to some extent, these three
classes of viscous models have very high degeneracy with each other, and
deviate slightly from the ideal fluid consequence. Subsequently, without the
loss of generality, to investigate the traversabilities, energy conditions and
stability for the wormhole solution, we study the wormhole solution of the
constant redshift function of the viscous $\omega$CDM model with a constant
bulk viscosity coefficient. We obtain the following conclusions: the value of
traversal velocity decreases for decreasing bulk viscosity, and the traversal
velocity for a traveler depends on not only the wormhole geometry but also the
effects of cosmological background evolution; the null energy condition will be
violated more clearly when the bulk viscosity or the cosmic expansion velocity
decreases; for the case of a positive surface energy density, the range of the
junction radius decreases and the values of the parameter $\lambda$ are further
restricted when the throat radius of the wormhole $r_0/M$ increases, bulk
viscosity coefficient $\zeta_0$ decreases and present-day Hubble parameter
$H_0$ decreases, respectively; for the case of a negative surface energy
density, by increasing $r_0/M$, decreasing $\zeta_0$ and increasing $H_0$, the
values of the parameter $\lambda$ are less restricted, one may conclude that
the total stability region increases, and the range of the junction radius
increases, increases and decreases, respectively. \end{abstract}
| [
{
"created": "Sat, 5 Nov 2016 08:29:59 GMT",
"version": "v1"
},
{
"created": "Thu, 23 Dec 2021 10:45:59 GMT",
"version": "v2"
},
{
"created": "Fri, 7 Jan 2022 17:16:54 GMT",
"version": "v3"
}
] | 2022-01-10 | [
[
"Wang",
"Deng",
""
]
] | We study the static and spherically symmetric wormhole spacetime configurations at present time in a viscous universe. Considering three classes of viscous models, i.e., bulk viscosity as a function of Hubble constant $H_0$, present cosmic temperature $T_0$ and dark energy density $\rho_0$, respectively, we obtain several wormhole solutions. Through the analysis for the anisotropic solutions, we conclude that, to some extent, these three classes of viscous models have very high degeneracy with each other, and deviate slightly from the ideal fluid consequence. Subsequently, without the loss of generality, to investigate the traversabilities, energy conditions and stability for the wormhole solution, we study the wormhole solution of the constant redshift function of the viscous $\omega$CDM model with a constant bulk viscosity coefficient. We obtain the following conclusions: the value of traversal velocity decreases for decreasing bulk viscosity, and the traversal velocity for a traveler depends on not only the wormhole geometry but also the effects of cosmological background evolution; the null energy condition will be violated more clearly when the bulk viscosity or the cosmic expansion velocity decreases; for the case of a positive surface energy density, the range of the junction radius decreases and the values of the parameter $\lambda$ are further restricted when the throat radius of the wormhole $r_0/M$ increases, bulk viscosity coefficient $\zeta_0$ decreases and present-day Hubble parameter $H_0$ decreases, respectively; for the case of a negative surface energy density, by increasing $r_0/M$, decreasing $\zeta_0$ and increasing $H_0$, the values of the parameter $\lambda$ are less restricted, one may conclude that the total stability region increases, and the range of the junction radius increases, increases and decreases, respectively. \end{abstract} |
2311.00348 | Sung-Won Kim | Sung-Won Kim | Wormhole Effective Mass and Gravitational Waves by Binary Systems
Containing Wormhole | 9 pages, 7 figures | null | null | null | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by-nc-sa/4.0/ | We considered the generation of gravitational waves by the binary system
associated with a wormhole. In the Newtonian limit, the gravitational potential
of a wormhole requires the effective mass of the wormhole taking into account
radial tension effects. This definition allows us to derive gravitational wave
production in homogeneous and heterogeneous binary systems. Therefore, we
studied gravitational waves generation by orbiting wormhole-wormhole and
wormhole-black hole binary systems before coalescence. Cases involving negative
mass require more careful handling. We also calculated the energy loss to
gravitational radiation by a particle orbiting around the wormhole and by a
particle moving straight through the wormhole mouth, respectively.
| [
{
"created": "Wed, 1 Nov 2023 07:43:49 GMT",
"version": "v1"
},
{
"created": "Tue, 7 Nov 2023 07:11:18 GMT",
"version": "v2"
}
] | 2023-11-08 | [
[
"Kim",
"Sung-Won",
""
]
] | We considered the generation of gravitational waves by the binary system associated with a wormhole. In the Newtonian limit, the gravitational potential of a wormhole requires the effective mass of the wormhole taking into account radial tension effects. This definition allows us to derive gravitational wave production in homogeneous and heterogeneous binary systems. Therefore, we studied gravitational waves generation by orbiting wormhole-wormhole and wormhole-black hole binary systems before coalescence. Cases involving negative mass require more careful handling. We also calculated the energy loss to gravitational radiation by a particle orbiting around the wormhole and by a particle moving straight through the wormhole mouth, respectively. |
2103.05039 | Ernesto Contreras | A. Ramos, C. Arias, E. Fuenmayor and E. Contreras | Class I polytropes for anisotropic matter | null | Eur. Phys. J. C 81, 203 (2021) | 10.1140/epjc/s10052-021-09002-1 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we study class I interior solutions supported by anisotropic
polytropes. The generalized Lane--Emden equation compatible with the embedding
condition is obtained and solved for a different set of parameters in both the
isothermal and non--isothermal regimes. For completeness, the Tolman mass is
computed and analysed to some extend. As a complementary study we consider the
impact of the Karmarkar condition on the mass and the Tolman mass functions
respectively. Comparison with other results in literature are discussed.
| [
{
"created": "Mon, 8 Mar 2021 19:50:51 GMT",
"version": "v1"
}
] | 2021-03-10 | [
[
"Ramos",
"A.",
""
],
[
"Arias",
"C.",
""
],
[
"Fuenmayor",
"E.",
""
],
[
"Contreras",
"E.",
""
]
] | In this work we study class I interior solutions supported by anisotropic polytropes. The generalized Lane--Emden equation compatible with the embedding condition is obtained and solved for a different set of parameters in both the isothermal and non--isothermal regimes. For completeness, the Tolman mass is computed and analysed to some extend. As a complementary study we consider the impact of the Karmarkar condition on the mass and the Tolman mass functions respectively. Comparison with other results in literature are discussed. |
1607.03839 | David Delphenich | D. H. Delphenich | On the local integrability of almost-product structures defined by
space-time metrics | 30 pages, 1 figure, 1 table | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The splitting of the tangent bundle of space-time into temporal and spatial
sub-bundles defines an almost-product structure. In particular, any space-time
metric can be locally expressed in time-orthogonal form, in such a way that
whether or not that almost-product structure is locally generated by a
coordinate chart is a matter of the integrability of the Pfaff equation that
the temporal 1-form of that expression for the metric defines. When one applies
that analysis to the known exact solutions to the Einstein field equations, one
finds that many of the common ones are completely-integrable, although some of
the physically-interesting ones are not.
| [
{
"created": "Wed, 13 Jul 2016 17:54:00 GMT",
"version": "v1"
}
] | 2016-07-14 | [
[
"Delphenich",
"D. H.",
""
]
] | The splitting of the tangent bundle of space-time into temporal and spatial sub-bundles defines an almost-product structure. In particular, any space-time metric can be locally expressed in time-orthogonal form, in such a way that whether or not that almost-product structure is locally generated by a coordinate chart is a matter of the integrability of the Pfaff equation that the temporal 1-form of that expression for the metric defines. When one applies that analysis to the known exact solutions to the Einstein field equations, one finds that many of the common ones are completely-integrable, although some of the physically-interesting ones are not. |
gr-qc/9901049 | Boisseau | B. Boisseau | Dynamics of a relativistic Rankine vortex for a two-constituent
superfluid in a weak perturbation of cylindrical symmetry | latex, 16 pages, 0 figure | null | null | null | gr-qc | null | From a recent study of a stationary cylindrical solution for a relativistic
two-constituent superfluid at low temperature limit, we propose to specify this
solution under the form of a relativistic generalisation of a Rankine vortex
(Potential vortex whose the core has a solid body rotation).Then we establish
the dynamics of the central line of this vortex by supposing that the deviation
from the cylindrical configuration is weak in the neighbourhood of the core of
the vortex. In "stiff" material the Nambu-Goto equations are obtained.
| [
{
"created": "Mon, 18 Jan 1999 14:34:21 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Boisseau",
"B.",
""
]
] | From a recent study of a stationary cylindrical solution for a relativistic two-constituent superfluid at low temperature limit, we propose to specify this solution under the form of a relativistic generalisation of a Rankine vortex (Potential vortex whose the core has a solid body rotation).Then we establish the dynamics of the central line of this vortex by supposing that the deviation from the cylindrical configuration is weak in the neighbourhood of the core of the vortex. In "stiff" material the Nambu-Goto equations are obtained. |
1903.08921 | Juan Mena-Fern\'andez | Juan Mena-Fern\'andez and Luis Manuel Gonz\'alez-Romero | Piecewise polytropic meshing and refinement method for the
reconstruction of the neutron star equation of state using tidal
deformabilities and constraints in the piecewise polytropic parameters given
by the GW170817 event | 12 pages, 8 figures. arXiv admin note: substantial text overlap with
arXiv:1901.10851 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we present a new approach to the inverse problem for
relativistic stars using the piecewise polytropic parametrization of the
equation of state. The algorithm is a piecewise polytropic meshing and
refinement method that reconstructs the neutron star equation of state from
experimental data of the mass and the tidal Love parameter. We use an initial
mesh of 65536 equations of state in a 4-volume of piecewise polytropic
parameters that contains most of the candidate equations of state used today.
The refinement process drives us to the reconstruction of the equation of state
with a certain precision. Using the reconstructed equation of state, we
calculate predictions for quasinormal modes and slow rotation parameters.
In order to check the meshing and refinement method, we use as input data a
few (6) configurations of a given equation of state. We reconstruct the
equation of state in a quite good approximation, and then we compare the curves
of physical parameters from the original equation of state and the
reconstructed one. We obtain a relative difference for all the parameters
smaller than 7.5%.
We also study the constraints that impose the GW170817 event on the piecewise
polytropic parameters $\{{\log_{10}p_1},{\Gamma_1},{\Gamma_2},{\Gamma_3}\}$. We
use the waveform model TaylorF2 for the low-spin scenario, and see that the
EOSs that lie outside the 90% credible region when
${\bar{\lambda}^{tid}_1}={\bar{\lambda}^{tid}_2}$ define a zone of polytropic
parameters that does not depend on ${\Gamma_3}$.
| [
{
"created": "Thu, 21 Mar 2019 10:55:47 GMT",
"version": "v1"
}
] | 2019-03-22 | [
[
"Mena-Fernández",
"Juan",
""
],
[
"González-Romero",
"Luis Manuel",
""
]
] | In this paper we present a new approach to the inverse problem for relativistic stars using the piecewise polytropic parametrization of the equation of state. The algorithm is a piecewise polytropic meshing and refinement method that reconstructs the neutron star equation of state from experimental data of the mass and the tidal Love parameter. We use an initial mesh of 65536 equations of state in a 4-volume of piecewise polytropic parameters that contains most of the candidate equations of state used today. The refinement process drives us to the reconstruction of the equation of state with a certain precision. Using the reconstructed equation of state, we calculate predictions for quasinormal modes and slow rotation parameters. In order to check the meshing and refinement method, we use as input data a few (6) configurations of a given equation of state. We reconstruct the equation of state in a quite good approximation, and then we compare the curves of physical parameters from the original equation of state and the reconstructed one. We obtain a relative difference for all the parameters smaller than 7.5%. We also study the constraints that impose the GW170817 event on the piecewise polytropic parameters $\{{\log_{10}p_1},{\Gamma_1},{\Gamma_2},{\Gamma_3}\}$. We use the waveform model TaylorF2 for the low-spin scenario, and see that the EOSs that lie outside the 90% credible region when ${\bar{\lambda}^{tid}_1}={\bar{\lambda}^{tid}_2}$ define a zone of polytropic parameters that does not depend on ${\Gamma_3}$. |
gr-qc/0103071 | Valeri Frolov | V. Frolov and D. Singh | Quantum Radiation of Uniformly Accelerated Spherical Mirrors | 17 pages, no figures, new references added | Class.Quant.Grav.18:3025-3038,2001 | 10.1088/0264-9381/18/15/316 | null | gr-qc | null | We study quantum radiation generated by a uniformly accelerated motion of
small spherical mirrors. To obtain Green's function for a scalar massless field
we use Wick's rotation. In the Euclidean domain the problem is reduced to
finding an electric potential in 4D flat space in the presence of a metallic
toroidal boundary. The latter problem is solved by a separation of variables.
After performing an inverse Wick's rotation we obtain the Hadamard function in
the wave-zone regime and use it to calculate the vacuum fluctuations and the
vacuum expectation for the energy density flux in the wave zone.
| [
{
"created": "Tue, 20 Mar 2001 08:47:35 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Jun 2001 20:39:56 GMT",
"version": "v2"
}
] | 2014-11-17 | [
[
"Frolov",
"V.",
""
],
[
"Singh",
"D.",
""
]
] | We study quantum radiation generated by a uniformly accelerated motion of small spherical mirrors. To obtain Green's function for a scalar massless field we use Wick's rotation. In the Euclidean domain the problem is reduced to finding an electric potential in 4D flat space in the presence of a metallic toroidal boundary. The latter problem is solved by a separation of variables. After performing an inverse Wick's rotation we obtain the Hadamard function in the wave-zone regime and use it to calculate the vacuum fluctuations and the vacuum expectation for the energy density flux in the wave zone. |
gr-qc/0703091 | Jungjai Lee | Jungjai Lee and Hyeong-Chan Kim | Black string and velocity frame dragging | 8 pages, no figure, some corrections | Mod.Phys.Lett.A23:305-313,2008 | 10.1142/S0217732308026418 | null | gr-qc hep-th | null | We investigate velocity frame dragging with the boosted Schwarzschild black
string solution and the boosted Kaluza-Klein bubble solution, in which a
translational symmetry along the boosted $z$-coordinate is implemented. The
velocity frame dragging effect can be nullified by the motion of an observer
using the boost symmetry along the $z-$coordinate if it is not compact.
However, in spacetime with the compact $z-$coordinate, we show that the effect
cannot be removed since the compactification breaks the global Lorentz boost
symmetry. As a result, the comoving velocity is dependent on $r$ and the
momentum parameter along the $z-$coordinate becomes an observer independent
characteristic quantity of the black string and bubble solutions. The dragging
induces a spherical ergo-region around the black string.
| [
{
"created": "Sat, 17 Mar 2007 15:22:02 GMT",
"version": "v1"
},
{
"created": "Thu, 22 Mar 2007 08:06:08 GMT",
"version": "v2"
},
{
"created": "Wed, 25 Apr 2007 03:54:23 GMT",
"version": "v3"
},
{
"created": "Sat, 15 Sep 2007 12:59:16 GMT",
"version": "v4"
},
{
"created": "Sun, 13 Jan 2008 11:14:01 GMT",
"version": "v5"
},
{
"created": "Wed, 27 Feb 2008 06:36:59 GMT",
"version": "v6"
}
] | 2008-11-26 | [
[
"Lee",
"Jungjai",
""
],
[
"Kim",
"Hyeong-Chan",
""
]
] | We investigate velocity frame dragging with the boosted Schwarzschild black string solution and the boosted Kaluza-Klein bubble solution, in which a translational symmetry along the boosted $z$-coordinate is implemented. The velocity frame dragging effect can be nullified by the motion of an observer using the boost symmetry along the $z-$coordinate if it is not compact. However, in spacetime with the compact $z-$coordinate, we show that the effect cannot be removed since the compactification breaks the global Lorentz boost symmetry. As a result, the comoving velocity is dependent on $r$ and the momentum parameter along the $z-$coordinate becomes an observer independent characteristic quantity of the black string and bubble solutions. The dragging induces a spherical ergo-region around the black string. |
2210.00007 | Oscar Castillo Felisola Dr. | Oscar Castillo-Felisola and Dominic T. Price and Mattia Scomparin | Cadabra and Python algorithms in General Relativity and Cosmology II:
Gravitational Waves | 32 pages, 3 figures, cadabra code blocks. For associated files, see
https://gitlab.com/cdbgr/cadabra-gravity-II | null | 10.1016/j.cpc.2023.108748 | null | gr-qc cs.MS physics.class-ph physics.comp-ph | http://creativecommons.org/licenses/by/4.0/ | Computer Algebra Systems (CASs) like Cadabra Software play a prominent role
in a wide range of research activities in physics and related fields. We show
how Cadabra language is easily implemented in the well established Python
programming framework, gaining excellent flexibility and customization to
address the issue of tensor perturbations in General Relativity. We obtain a
performing algorithm to decompose tensorial quantities up to any perturbative
order of the metric. The features of our code are tested by discussing some
concrete computational issues in research activities related to
first/higher-order gravitational waves.
| [
{
"created": "Fri, 30 Sep 2022 16:58:21 GMT",
"version": "v1"
}
] | 2023-05-17 | [
[
"Castillo-Felisola",
"Oscar",
""
],
[
"Price",
"Dominic T.",
""
],
[
"Scomparin",
"Mattia",
""
]
] | Computer Algebra Systems (CASs) like Cadabra Software play a prominent role in a wide range of research activities in physics and related fields. We show how Cadabra language is easily implemented in the well established Python programming framework, gaining excellent flexibility and customization to address the issue of tensor perturbations in General Relativity. We obtain a performing algorithm to decompose tensorial quantities up to any perturbative order of the metric. The features of our code are tested by discussing some concrete computational issues in research activities related to first/higher-order gravitational waves. |
1504.03636 | Yuri Bonder | Yuri Bonder | Lorentz violation in the gravity sector: The t puzzle | null | Phys. Rev. D 91, 125002 (2015) | 10.1103/PhysRevD.91.125002 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Lorentz violation is a candidate quantum-gravity signal, and the
Standard-Model Extension (SME) is a widely used parametrization of such a
violation. In the gravitational SME sector, there is an elusive coefficient for
which no effects have been found. This is known as the $t$ puzzle and, to date,
it has no compelling explanation. This paper analyzes whether there is a
fundamental explanation for the $t$ puzzle. To tackle this question, several
approaches are followed. Mainly, redefinitions of the dynamical fields are
studied, showing that other SME coefficients can be moved to nongravitational
sectors. It is also found that the gravity SME sector can be consistently
treated \textit{\`a la} Palatini, and that, in the presence of spacetime
boundaries, it is possible to correct its action to get the desired equations
of motion. Moreover, through a reformulation as a Lanczos-type tensor, some
problematic features of the $t$ term, which should arise at the
phenomenological level, are revealed. The most important conclusion of the
paper is that there is no evidence of a fundamental explanation for the $t$
puzzle, suggesting that it may be linked to the approximations taken at the
phenomenological level.
| [
{
"created": "Tue, 14 Apr 2015 17:43:30 GMT",
"version": "v1"
},
{
"created": "Mon, 25 May 2015 23:17:29 GMT",
"version": "v2"
}
] | 2015-06-03 | [
[
"Bonder",
"Yuri",
""
]
] | Lorentz violation is a candidate quantum-gravity signal, and the Standard-Model Extension (SME) is a widely used parametrization of such a violation. In the gravitational SME sector, there is an elusive coefficient for which no effects have been found. This is known as the $t$ puzzle and, to date, it has no compelling explanation. This paper analyzes whether there is a fundamental explanation for the $t$ puzzle. To tackle this question, several approaches are followed. Mainly, redefinitions of the dynamical fields are studied, showing that other SME coefficients can be moved to nongravitational sectors. It is also found that the gravity SME sector can be consistently treated \textit{\`a la} Palatini, and that, in the presence of spacetime boundaries, it is possible to correct its action to get the desired equations of motion. Moreover, through a reformulation as a Lanczos-type tensor, some problematic features of the $t$ term, which should arise at the phenomenological level, are revealed. The most important conclusion of the paper is that there is no evidence of a fundamental explanation for the $t$ puzzle, suggesting that it may be linked to the approximations taken at the phenomenological level. |
1605.09121 | Jie-Xiong Mo | Gu-Qiang Li, Jie-Xiong Mo | Phase transition and thermodynamic geometry of $f(R)$ AdS black holes in
the grand canonical ensemble | null | Phys. Rev. D 93, 124021 (2016) | 10.1103/PhysRevD.93.124021 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The phase transition of four-dimensional charged AdS black hole solution in
the $R+f(R)$ gravity with constant curvature is investigated in the grand
canonical ensemble, where we find novel characteristics quite different from
that in canonical ensemble. There exists no critical point for $T-S$ curve
while in former research critical point was found for both the $T-S$ curve and
$T-r_+$ curve when the electric charge of $f(R)$ black holes is kept fixed.
Moreover, we derive the explicit expression for the specific heat, the analog
of volume expansion coefficient and isothermal compressibility coefficient when
the electric potential of $f(R)$ AdS black hole is fixed. The specific heat
$C_\Phi$ encounters a divergence when $0<\Phi<b$ while there is no divergence
for the case $\Phi>b$. This finding also differs from the result in the
canonical ensemble, where there may be two, one or no divergence points for the
specific heat $C_Q$. To examine the phase structure newly found in the grand
canonical ensemble, we appeal to the well-known thermodynamic geometry tools
and derive the analytic expressions for both the Weinhold scalar curvature and
Ruppeiner scalar curvature. It is shown that they diverge exactly where the
specific heat $C_\Phi$ diverges.
| [
{
"created": "Mon, 30 May 2016 07:13:10 GMT",
"version": "v1"
},
{
"created": "Sat, 11 Jun 2016 23:55:49 GMT",
"version": "v2"
}
] | 2016-06-22 | [
[
"Li",
"Gu-Qiang",
""
],
[
"Mo",
"Jie-Xiong",
""
]
] | The phase transition of four-dimensional charged AdS black hole solution in the $R+f(R)$ gravity with constant curvature is investigated in the grand canonical ensemble, where we find novel characteristics quite different from that in canonical ensemble. There exists no critical point for $T-S$ curve while in former research critical point was found for both the $T-S$ curve and $T-r_+$ curve when the electric charge of $f(R)$ black holes is kept fixed. Moreover, we derive the explicit expression for the specific heat, the analog of volume expansion coefficient and isothermal compressibility coefficient when the electric potential of $f(R)$ AdS black hole is fixed. The specific heat $C_\Phi$ encounters a divergence when $0<\Phi<b$ while there is no divergence for the case $\Phi>b$. This finding also differs from the result in the canonical ensemble, where there may be two, one or no divergence points for the specific heat $C_Q$. To examine the phase structure newly found in the grand canonical ensemble, we appeal to the well-known thermodynamic geometry tools and derive the analytic expressions for both the Weinhold scalar curvature and Ruppeiner scalar curvature. It is shown that they diverge exactly where the specific heat $C_\Phi$ diverges. |
2211.02948 | Umananda Dev Goswami | Gayatri Mohan and Umananda Dev Goswami | Galactic rotation curves of spiral galaxies and dark matter in f(R,T)
gravity theory | 14 pages, 3 figures; published version | null | 10.1142/S0219887824500828 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Galactic rotation curve is a powerful indicator of the state of the
gravitational field within a galaxy. The flatness of these curves indicates the
presence of dark matter in galaxies and their clusters. In this paper, we focus
on the possibility of explaining the rotation curves of spiral galaxies without
postulating the existence of dark matter in the framework of $f(\mathcal{R},T)$
gravity, where the gravitational Lagrangian is written by an arbitrary function
of $\mathcal{R}$, the Ricci scalar and of $T$, the trace of energy-momentum
tensor $T_{\mu\nu}$. We derive the gravitational field equations in this
gravity theory for the static spherically symmetric spacetime and solve the
equations for metric coefficients using a specific model that has minimal
coupling between matter and geometry. The orbital motion of a massive test
particle moving in a stable circular orbit is considered and the behavior of
its tangential velocity with the help of the considered model is studied. We
compare the theoretical result predicted by the model with observations of a
sample of nineteen galaxies by generating and fitting rotation curves for the
test particle to check the viability of the model. It is observed that the
model could almost successfully explain the galactic dynamics of these galaxies
without the need of dark matter at large distances from the galactic center.
| [
{
"created": "Sat, 5 Nov 2022 17:25:39 GMT",
"version": "v1"
},
{
"created": "Sat, 25 Nov 2023 10:16:39 GMT",
"version": "v2"
}
] | 2023-11-28 | [
[
"Mohan",
"Gayatri",
""
],
[
"Goswami",
"Umananda Dev",
""
]
] | Galactic rotation curve is a powerful indicator of the state of the gravitational field within a galaxy. The flatness of these curves indicates the presence of dark matter in galaxies and their clusters. In this paper, we focus on the possibility of explaining the rotation curves of spiral galaxies without postulating the existence of dark matter in the framework of $f(\mathcal{R},T)$ gravity, where the gravitational Lagrangian is written by an arbitrary function of $\mathcal{R}$, the Ricci scalar and of $T$, the trace of energy-momentum tensor $T_{\mu\nu}$. We derive the gravitational field equations in this gravity theory for the static spherically symmetric spacetime and solve the equations for metric coefficients using a specific model that has minimal coupling between matter and geometry. The orbital motion of a massive test particle moving in a stable circular orbit is considered and the behavior of its tangential velocity with the help of the considered model is studied. We compare the theoretical result predicted by the model with observations of a sample of nineteen galaxies by generating and fitting rotation curves for the test particle to check the viability of the model. It is observed that the model could almost successfully explain the galactic dynamics of these galaxies without the need of dark matter at large distances from the galactic center. |
1709.02818 | Sante Carloni Dr | Sante Carloni, Daniele Vernieri | The covariant Tolman-Oppenheimer-Volkoff equations I: The isotropic case | 12 pages, 2 figures | Phys. Rev. D 97, 124056 (2018) | 10.1103/PhysRevD.97.124056 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct a covariant version of the Tolman-Oppenheimer-Volkoff equations
in the case of isotropic sources. The new equations make evident the
mathematical problems in the determination of interior solutions of
relativistic stellar objects. Using a reconstruction algorithm we find two
physically interesting generalisations of previously known stellar interior
solutions. The variables that we use also allow an easier formulation of known
generating theorems for solutions associated to relativistic stellar objects.
| [
{
"created": "Fri, 8 Sep 2017 18:01:02 GMT",
"version": "v1"
}
] | 2018-06-27 | [
[
"Carloni",
"Sante",
""
],
[
"Vernieri",
"Daniele",
""
]
] | We construct a covariant version of the Tolman-Oppenheimer-Volkoff equations in the case of isotropic sources. The new equations make evident the mathematical problems in the determination of interior solutions of relativistic stellar objects. Using a reconstruction algorithm we find two physically interesting generalisations of previously known stellar interior solutions. The variables that we use also allow an easier formulation of known generating theorems for solutions associated to relativistic stellar objects. |
1905.00971 | Geoffrey Comp\`ere | Geoffrey Comp\`ere, Adrien Fiorucci and Romain Ruzziconi | The $\Lambda$-BMS$_4$ group of dS$_4$ and new boundary conditions for
AdS$_4$ | 42 pages, 1 figure, attached Mathematica notebook, corrigendum
version | null | 10.1088/1361-6382/ab3d4b | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using the dictionary between Bondi and Fefferman-Graham gauges, we identify
the analogues of the Bondi news, Bondi mass and Bondi angular momentum aspects
at the boundary of generic asymptotically locally (A)dS$_4$ spacetimes. We
introduce the $\Lambda$-BMS$_4$ group as the residual symmetry group of the
metric in Bondi gauge after boundary gauge fixing. This group consists of
infinite-dimensional non-abelian supertranslations and superrotations and it
reduces in the asymptotically flat limit to the extended BMS$_4$ group.
Furthermore, we present new boundary conditions for asymptotically locally
AdS$_4$ spacetimes which admit $\mathbb R$ times the group of area-preserving
diffeomorphisms as the asymptotic symmetry group. The boundary conditions
amount to fix 2 components of the holographic stress-tensor while allowing 2
components of the boundary metric to fluctuate. They correspond to a
deformation of a holographic CFT$_3$ which is coupled to a fluctuating spatial
metric of fixed area.
| [
{
"created": "Thu, 2 May 2019 21:33:37 GMT",
"version": "v1"
},
{
"created": "Wed, 4 Sep 2019 12:15:09 GMT",
"version": "v2"
},
{
"created": "Fri, 10 Feb 2023 13:20:51 GMT",
"version": "v3"
}
] | 2023-02-13 | [
[
"Compère",
"Geoffrey",
""
],
[
"Fiorucci",
"Adrien",
""
],
[
"Ruzziconi",
"Romain",
""
]
] | Using the dictionary between Bondi and Fefferman-Graham gauges, we identify the analogues of the Bondi news, Bondi mass and Bondi angular momentum aspects at the boundary of generic asymptotically locally (A)dS$_4$ spacetimes. We introduce the $\Lambda$-BMS$_4$ group as the residual symmetry group of the metric in Bondi gauge after boundary gauge fixing. This group consists of infinite-dimensional non-abelian supertranslations and superrotations and it reduces in the asymptotically flat limit to the extended BMS$_4$ group. Furthermore, we present new boundary conditions for asymptotically locally AdS$_4$ spacetimes which admit $\mathbb R$ times the group of area-preserving diffeomorphisms as the asymptotic symmetry group. The boundary conditions amount to fix 2 components of the holographic stress-tensor while allowing 2 components of the boundary metric to fluctuate. They correspond to a deformation of a holographic CFT$_3$ which is coupled to a fluctuating spatial metric of fixed area. |
2211.10723 | Gerard Hooft 't | Gerard t Hooft | How studying black hole theory may help us to quantise gravity | 14 pages, 3 figures, presented at the Conference on "Eternity between
and Space and Time", Padova, May 19-21, 2022 | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Black holes are more than just odd-looking curiosities in gravity theory.
They uniquely intertwine the basic principles of General Relativity with those
of Quantum Theory. Just by demanding that they nevertheless obey acceptable
laws of dynamics, just like stars and planets, we hit upon strange structures
that must play key roles in the quantum effects that we expect in the
gravitational force at ultrashort distance scales. It is explained why, in our
approach to address the problem of information conservation, the usual
expression for the temperature of Hawking's radiation is off by a factor 2.
| [
{
"created": "Sat, 19 Nov 2022 15:37:16 GMT",
"version": "v1"
},
{
"created": "Thu, 24 Nov 2022 21:21:40 GMT",
"version": "v2"
}
] | 2022-11-28 | [
[
"Hooft",
"Gerard t",
""
]
] | Black holes are more than just odd-looking curiosities in gravity theory. They uniquely intertwine the basic principles of General Relativity with those of Quantum Theory. Just by demanding that they nevertheless obey acceptable laws of dynamics, just like stars and planets, we hit upon strange structures that must play key roles in the quantum effects that we expect in the gravitational force at ultrashort distance scales. It is explained why, in our approach to address the problem of information conservation, the usual expression for the temperature of Hawking's radiation is off by a factor 2. |
1410.5983 | Hugo Ferreira | Hugo R. C. Ferreira, Jorma Louko | Renormalized vacuum polarization on rotating warped AdS3 black holes | 25 pages, 2 figures. v2: minor typos corrections, published version | Phys.Rev.D91 (2015), 024038 | 10.1103/PhysRevD.91.024038 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compute the renormalized vacuum polarization of a massive scalar field in
the Hartle-Hawking state on (2+1)-dimensional rotating, spacelike stretched
black hole solutions to Topologically Massive Gravity, surrounded by a
Dirichlet mirror that makes the state well defined. The Feynman propagator is
written as a mode sum on the complex Riemannian section of the spacetime, and a
Hadamard renormalization procedure is implemented by matching to a mode sum on
the complex Riemannian section of a rotating Minkowski spacetime. No analytic
continuation in the angular momentum parameter is invoked. Selected numerical
results are given, demonstrating the numerical efficacy of the method. We
anticipate that this method can be extended to wider classes of rotating black
hole spacetimes, in particular to the Kerr spacetime in four dimensions.
| [
{
"created": "Wed, 22 Oct 2014 10:38:12 GMT",
"version": "v1"
},
{
"created": "Wed, 28 Jan 2015 14:21:25 GMT",
"version": "v2"
}
] | 2015-01-29 | [
[
"Ferreira",
"Hugo R. C.",
""
],
[
"Louko",
"Jorma",
""
]
] | We compute the renormalized vacuum polarization of a massive scalar field in the Hartle-Hawking state on (2+1)-dimensional rotating, spacelike stretched black hole solutions to Topologically Massive Gravity, surrounded by a Dirichlet mirror that makes the state well defined. The Feynman propagator is written as a mode sum on the complex Riemannian section of the spacetime, and a Hadamard renormalization procedure is implemented by matching to a mode sum on the complex Riemannian section of a rotating Minkowski spacetime. No analytic continuation in the angular momentum parameter is invoked. Selected numerical results are given, demonstrating the numerical efficacy of the method. We anticipate that this method can be extended to wider classes of rotating black hole spacetimes, in particular to the Kerr spacetime in four dimensions. |
2105.12632 | Daphne O. Klemme | Vincent Moncrief (1) and Nishanth Gudapati (2) ((1) Yale University,
(2) Harvard University) | A Positive-Definite Energy Functional for the Axisymmetric Perturbations
of Kerr-Newman Black Holes | 131 pages, 0 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by-nc-nd/4.0/ | We consider the axisymmetric, linear perturbations of Kerr-Newman black
holes, allowing for arbitrarily large (but subextremal) angular momentum and
electric charge. By exploiting the famous Carter-Robinson identities, developed
previously for the proofs of (stationary) black hole uniqueness results, we
construct a positive-definite energy functional for these perturbations and
establish its conservation for a class of (coupled, gravitational and
electromagnetic) solutions to the linearized field equations. Our analysis
utilizes the familiar (Hamiltonian) reduction of the field equations (for
axisymmetric geometries) to a system of wave map fields coupled to a
2+1-dimensional Lorentzian metric on the relevant quotient 3-manifold. The
propagating `dynamical degrees of freedom' of this system are entirely captured
by the wave map fields, which take their values in a four dimensional,
negatively curved (complex hyperbolic) Riemannian target space whereas the
base-space Lorentzian metric is entirely determined, in our setup, by elliptic
constraints and gauge conditions.
| [
{
"created": "Wed, 26 May 2021 15:46:52 GMT",
"version": "v1"
}
] | 2021-05-27 | [
[
"Moncrief",
"Vincent",
""
],
[
"Gudapati",
"Nishanth",
""
]
] | We consider the axisymmetric, linear perturbations of Kerr-Newman black holes, allowing for arbitrarily large (but subextremal) angular momentum and electric charge. By exploiting the famous Carter-Robinson identities, developed previously for the proofs of (stationary) black hole uniqueness results, we construct a positive-definite energy functional for these perturbations and establish its conservation for a class of (coupled, gravitational and electromagnetic) solutions to the linearized field equations. Our analysis utilizes the familiar (Hamiltonian) reduction of the field equations (for axisymmetric geometries) to a system of wave map fields coupled to a 2+1-dimensional Lorentzian metric on the relevant quotient 3-manifold. The propagating `dynamical degrees of freedom' of this system are entirely captured by the wave map fields, which take their values in a four dimensional, negatively curved (complex hyperbolic) Riemannian target space whereas the base-space Lorentzian metric is entirely determined, in our setup, by elliptic constraints and gauge conditions. |
gr-qc/9304029 | Piotr T. Chrusciel | Piotr T. Chrusciel | On completeness of orbits of Killing vector fields | 16 pages, Latex, preprint NSF-ITP-93-44 | Class.Quant.Grav.10:2091-2102,1993 | 10.1088/0264-9381/10/10/016 | null | gr-qc | null | A Theorem is proved which reduces the problem of completeness of orbits of
Killing vector fields in maximal globally hyperbolic, say vacuum, space--times
to some properties of the orbits near the Cauchy surface. In particular it is
shown that all Killing orbits are complete in maximal developements of
asymptotically flat Cauchy data, or of Cauchy data prescribed on a compact
manifold. This result gives a significant strengthening of the uniqueness
theorems for black holes.
| [
{
"created": "Wed, 21 Apr 1993 04:38:23 GMT",
"version": "v1"
}
] | 2010-04-06 | [
[
"Chrusciel",
"Piotr T.",
""
]
] | A Theorem is proved which reduces the problem of completeness of orbits of Killing vector fields in maximal globally hyperbolic, say vacuum, space--times to some properties of the orbits near the Cauchy surface. In particular it is shown that all Killing orbits are complete in maximal developements of asymptotically flat Cauchy data, or of Cauchy data prescribed on a compact manifold. This result gives a significant strengthening of the uniqueness theorems for black holes. |
2209.13829 | Alexander Grant | Alexander M. Grant and Jordan Moxon | Flux-balance laws in scalar self-force theory | 15+3 pages, 1 figure; v2: corrected typos and added appendix and
figure, "matches" published version | Phys. Rev. D 108, 104029 (2023) | 10.1103/PhysRevD.108.104029 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The motion of a radiating point particle can be represented by a series of
geodesics whose "constants" of motion evolve slowly with time. The evolution of
these constants of motion can be determined directly from the self-force
equations of motion. In the presence of spacetime symmetries, the situation
simplifies: there exist not only constants of motion conjugate to these
symmetries, but also conserved currents whose fluxes can be used to determine
their evolution. Such a relationship between point-particle motion and fluxes
of conserved currents is a flux-balance law. However, there exist constants of
motion that are not related to spacetime symmetries, the most notable example
of which is the Carter constant in the Kerr spacetime. In this paper, we first
present a new approach to flux-balance laws for spacetime symmetries, using the
techniques of symplectic currents and symmetry operators, which can also
generate more general conserved currents. We then derive flux-balance laws for
all constants of motion in the Kerr spacetime, using the fact that the
background, geodesic motion is integrable. For simplicity, we restrict
derivations in this paper to the scalar self-force problem. While generalizing
the discussion in this paper to the gravitational case will be straightforward,
there will be additional complications in turning these results into a
practical flux-balance law in this case.
| [
{
"created": "Wed, 28 Sep 2022 04:28:55 GMT",
"version": "v1"
},
{
"created": "Tue, 14 Nov 2023 22:46:52 GMT",
"version": "v2"
}
] | 2023-11-16 | [
[
"Grant",
"Alexander M.",
""
],
[
"Moxon",
"Jordan",
""
]
] | The motion of a radiating point particle can be represented by a series of geodesics whose "constants" of motion evolve slowly with time. The evolution of these constants of motion can be determined directly from the self-force equations of motion. In the presence of spacetime symmetries, the situation simplifies: there exist not only constants of motion conjugate to these symmetries, but also conserved currents whose fluxes can be used to determine their evolution. Such a relationship between point-particle motion and fluxes of conserved currents is a flux-balance law. However, there exist constants of motion that are not related to spacetime symmetries, the most notable example of which is the Carter constant in the Kerr spacetime. In this paper, we first present a new approach to flux-balance laws for spacetime symmetries, using the techniques of symplectic currents and symmetry operators, which can also generate more general conserved currents. We then derive flux-balance laws for all constants of motion in the Kerr spacetime, using the fact that the background, geodesic motion is integrable. For simplicity, we restrict derivations in this paper to the scalar self-force problem. While generalizing the discussion in this paper to the gravitational case will be straightforward, there will be additional complications in turning these results into a practical flux-balance law in this case. |
1910.09280 | M. D. Maia | Ivan S. Ferreira, C. Frajuca, Nadja S. Magalhaes, M. D. Maia, Claudio
M. G. Sousa | The Laser Gravitational Compass | Latex, four pages, no figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Using the observational properties of Einstein's gravitational field it is
shown that a minimum of four non-coplanar mass probes are necessary for the
Michelson and Morley interferometer to detect gravitational waves within the
context of General Relativity. With fewer probes, some alternative theories of
gravitation can also explain the observations. The conversion of the existing
gravitational wave detectors to four probes is also suggested.
| [
{
"created": "Mon, 21 Oct 2019 12:03:37 GMT",
"version": "v1"
}
] | 2019-10-22 | [
[
"Ferreira",
"Ivan S.",
""
],
[
"Frajuca",
"C.",
""
],
[
"Magalhaes",
"Nadja S.",
""
],
[
"Maia",
"M. D.",
""
],
[
"Sousa",
"Claudio M. G.",
""
]
] | Using the observational properties of Einstein's gravitational field it is shown that a minimum of four non-coplanar mass probes are necessary for the Michelson and Morley interferometer to detect gravitational waves within the context of General Relativity. With fewer probes, some alternative theories of gravitation can also explain the observations. The conversion of the existing gravitational wave detectors to four probes is also suggested. |
gr-qc/9703016 | null | Roustam M. Zalaletdinov (Queen Mary and Westfield College, London and
Department of Theoretical Physics, Institute of Nuclear Physics, Tashkent) | Averaging Problem in General Relativity, Macroscopic Gravity and Using
Einstein's Equations in Cosmology | 16 pages, RevTeX, submitted to Phys. Rev. D | Bull.Astron.Soc.India 25 (1997) 401-416 | null | QMW-AU-96018 (March 1996) | gr-qc astro-ph | null | The averaging problem in general relativity is briefly discussed. A new
setting of the problem as that of macroscopic description of gravitation is
proposed. A covariant space-time averaging procedure is described. The
structure of the geometry of macroscopic space-time, which follows from
averaging Cartan's structure equations, is described and the correlation
tensors present in the theory are discussed. The macroscopic field equations
(averaged Einstein's equations) derived in the framework of the approach are
presented and their structure is analysed. The correspondence principle for
macroscopic gravity is formulated and a definition of the stress-energy tensor
for the macroscopic gravitational field is proposed. It is shown that the
physical meaning of using Einstein's equations with a hydrodynamic
stress-energy tensor in looking for cosmological models means neglecting all
gravitational field correlations. The system of macroscopic gravity equations
to be solved when the correlations are taken into consideration is given and
described.
| [
{
"created": "Thu, 6 Mar 1997 19:01:49 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Zalaletdinov",
"Roustam M.",
"",
"Queen Mary and Westfield College, London and\n Department of Theoretical Physics, Institute of Nuclear Physics, Tashkent"
]
] | The averaging problem in general relativity is briefly discussed. A new setting of the problem as that of macroscopic description of gravitation is proposed. A covariant space-time averaging procedure is described. The structure of the geometry of macroscopic space-time, which follows from averaging Cartan's structure equations, is described and the correlation tensors present in the theory are discussed. The macroscopic field equations (averaged Einstein's equations) derived in the framework of the approach are presented and their structure is analysed. The correspondence principle for macroscopic gravity is formulated and a definition of the stress-energy tensor for the macroscopic gravitational field is proposed. It is shown that the physical meaning of using Einstein's equations with a hydrodynamic stress-energy tensor in looking for cosmological models means neglecting all gravitational field correlations. The system of macroscopic gravity equations to be solved when the correlations are taken into consideration is given and described. |
gr-qc/0003115 | Robin W. Tucker | Simon J. Clark, Robin W. Tucker | Gauge Symmetry and Gravito-Electromagnetism | 29 pages no-figs | Class.Quant.Grav.17:4125-4158,2000 | 10.1088/0264-9381/17/19/311 | null | gr-qc astro-ph | null | A tensor description of perturbative Einsteinian gravity about an arbitrary
background spacetime is developed. By analogy with the covariant laws of
electromagnetism in spacetime, gravito-electromagnetic potentials and fields
are defined to emulate electromagnetic gauge transformations under
substitutions belonging to the gauge symmetry group of perturbative
gravitation. These definitions have the advantage that on a flat background,
with the aid of a covariantly constant timelike vector field, a subset of the
linearised gravitational field equations can be written in a form that is fully
analogous to Maxwell's equations (without awkward factors of 4 and extraneous
tensor fields). It is shown how the remaining equations in the perturbed
gravitational system restrict the time dependence of solutions to these
equations and thereby prohibit the existence of propagating vector fields. The
induced gravito-electromagnetic Lorentz force on a test particle is evaluated
in terms of these fields together with the torque on a small gyroscope. It is
concluded that the analogy of perturbative gravity to Maxwell's description of
electromagnetism can be valuable for (quasi-)stationary gravitational phenomena
but that the analogy has its limitations.
| [
{
"created": "Fri, 31 Mar 2000 17:18:07 GMT",
"version": "v1"
},
{
"created": "Fri, 22 Sep 2000 15:35:58 GMT",
"version": "v2"
}
] | 2014-11-17 | [
[
"Clark",
"Simon J.",
""
],
[
"Tucker",
"Robin W.",
""
]
] | A tensor description of perturbative Einsteinian gravity about an arbitrary background spacetime is developed. By analogy with the covariant laws of electromagnetism in spacetime, gravito-electromagnetic potentials and fields are defined to emulate electromagnetic gauge transformations under substitutions belonging to the gauge symmetry group of perturbative gravitation. These definitions have the advantage that on a flat background, with the aid of a covariantly constant timelike vector field, a subset of the linearised gravitational field equations can be written in a form that is fully analogous to Maxwell's equations (without awkward factors of 4 and extraneous tensor fields). It is shown how the remaining equations in the perturbed gravitational system restrict the time dependence of solutions to these equations and thereby prohibit the existence of propagating vector fields. The induced gravito-electromagnetic Lorentz force on a test particle is evaluated in terms of these fields together with the torque on a small gyroscope. It is concluded that the analogy of perturbative gravity to Maxwell's description of electromagnetism can be valuable for (quasi-)stationary gravitational phenomena but that the analogy has its limitations. |
1306.4400 | Alberto Diez-Tejedor | Alberto Diez-Tejedor and Alma X. Gonzalez-Morales | No-go theorem for static scalar field dark matter halos with no Noether
charges | 6 pages, no figures. The Appendix A does not appear in the printed
version | Phys. Rev. D 88, 067302 (2013) | 10.1103/PhysRevD.88.067302 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Classical scalar fields have been considered as a possible effective
description of dark matter. We show that, for any metric theory of gravity, no
static, spherically symmetric, regular, spatially localized, attractive, stable
spacetime configuration can be sourced by the coherent excitation of a scalar
field with positive definite energy density and no Noether charges. In the
weak-field regime the result also applies for configurations with a repulsive
gravitational potential. This extends Derrick's theorem to the case of a
general (non-canonical) scalar field, including the self-gravitational effects.
Some possible ways out are briefly discussed.
| [
{
"created": "Wed, 19 Jun 2013 00:48:03 GMT",
"version": "v1"
},
{
"created": "Thu, 26 Sep 2013 13:50:16 GMT",
"version": "v2"
}
] | 2013-09-27 | [
[
"Diez-Tejedor",
"Alberto",
""
],
[
"Gonzalez-Morales",
"Alma X.",
""
]
] | Classical scalar fields have been considered as a possible effective description of dark matter. We show that, for any metric theory of gravity, no static, spherically symmetric, regular, spatially localized, attractive, stable spacetime configuration can be sourced by the coherent excitation of a scalar field with positive definite energy density and no Noether charges. In the weak-field regime the result also applies for configurations with a repulsive gravitational potential. This extends Derrick's theorem to the case of a general (non-canonical) scalar field, including the self-gravitational effects. Some possible ways out are briefly discussed. |
2401.17106 | Roman Konoplya | R. A. Konoplya | Two Regimes of Asymptotic Fall-off of a Massive Scalar Field in the
Schwarzschild-de Sitter Spacetime | 12 pages, 10 figures, revtex, new material and references added, the
version accepted for publication in Phys. Rev. D | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The decay behavior of a massless scalar field in the Schwarzschild-de Sitter
spacetime is well-known to follow an exponential law at asymptotically late
times $t \rightarrow \infty$. In contrast, a massive scalar field in the
asymptotically flat Schwarzschild background exhibits a decay with oscillatory
(sinusoidal) tails enveloped by a power law. We demonstrate that the asymptotic
decay of a massive scalar field in the Schwarzschild-de Sitter spacetime is
exponential. Specifically, if $\mu M \gg 1$, where $\mu$ and $M$ represent the
mass of the field and the black hole, respectively, the exponential decay is
also oscillatory. Conversely, in the regime of small $\mu M$, the decay is
purely exponential without oscillations. This distinction in decay regimes
underscores the fact that, for asymptotically de Sitter spacetimes, a
particular branch of quasinormal modes, instead of a "tail", governs the decay
at asymptotically late times. There are two branches of quasinormal modes for
the Schwarzschild-de Sitter spacetime: the modes of an asymptotically flat
black hole corrected by a non-zero $\Lambda$-term, and the modes of an empty de
Sitter spacetime corrected by the presence of a black hole. We show that the
latter branch is responsible for the asymptotic decay. When $\mu M$ is small,
the modes of pure de Sitter spacetime are purely imaginary (non-oscillatory),
while at intermediate and large $\mu M$ they have both real and imaginary
parts, what produces the two pictures of the asymptotic decay. In addition, we
show that the asymptotic decay of charged and higher dimensional black hole is
also exponential.
| [
{
"created": "Tue, 30 Jan 2024 15:42:17 GMT",
"version": "v1"
},
{
"created": "Sun, 4 Feb 2024 15:33:09 GMT",
"version": "v2"
},
{
"created": "Wed, 7 Feb 2024 10:52:12 GMT",
"version": "v3"
},
{
"created": "Mon, 15 Apr 2024 15:02:15 GMT",
"version": "v4"
}
] | 2024-04-16 | [
[
"Konoplya",
"R. A.",
""
]
] | The decay behavior of a massless scalar field in the Schwarzschild-de Sitter spacetime is well-known to follow an exponential law at asymptotically late times $t \rightarrow \infty$. In contrast, a massive scalar field in the asymptotically flat Schwarzschild background exhibits a decay with oscillatory (sinusoidal) tails enveloped by a power law. We demonstrate that the asymptotic decay of a massive scalar field in the Schwarzschild-de Sitter spacetime is exponential. Specifically, if $\mu M \gg 1$, where $\mu$ and $M$ represent the mass of the field and the black hole, respectively, the exponential decay is also oscillatory. Conversely, in the regime of small $\mu M$, the decay is purely exponential without oscillations. This distinction in decay regimes underscores the fact that, for asymptotically de Sitter spacetimes, a particular branch of quasinormal modes, instead of a "tail", governs the decay at asymptotically late times. There are two branches of quasinormal modes for the Schwarzschild-de Sitter spacetime: the modes of an asymptotically flat black hole corrected by a non-zero $\Lambda$-term, and the modes of an empty de Sitter spacetime corrected by the presence of a black hole. We show that the latter branch is responsible for the asymptotic decay. When $\mu M$ is small, the modes of pure de Sitter spacetime are purely imaginary (non-oscillatory), while at intermediate and large $\mu M$ they have both real and imaginary parts, what produces the two pictures of the asymptotic decay. In addition, we show that the asymptotic decay of charged and higher dimensional black hole is also exponential. |
2212.13561 | Alexander Ganz | Alexander Ganz, Paul Martens, Shinji Mukohyama, Ryo Namba | Bouncing Cosmology in VCDM | 15 pages, 8 figures; accepted version | null | 10.1088/1475-7516/2023/04/060 | RIKEN-iTHEMS-Report-22 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct an asymmetric bouncing scenario within the VCDM model - also
known as type-II minimally modified gravity -, a modified gravity theory with
two local physical degrees of freedom. The scenario is exempt of any ghost or
gradient instability, ad-hoc matching conditions or anisotropic stress issue
(BKL instability). It moreover succeeds in generating the cosmological
perturbations compatible with the observations. The scalar spectral index can
be adapted by the choice of the equation of state of the matter sector and the
form of the VCDM potential leading to an almost scale-invariant power spectrum.
Satisfying the CMB bounds on the tensor-to-scalar ratio leads to a blue tensor
spectrum.
| [
{
"created": "Tue, 27 Dec 2022 17:30:55 GMT",
"version": "v1"
},
{
"created": "Thu, 27 Apr 2023 12:39:29 GMT",
"version": "v2"
}
] | 2023-04-28 | [
[
"Ganz",
"Alexander",
""
],
[
"Martens",
"Paul",
""
],
[
"Mukohyama",
"Shinji",
""
],
[
"Namba",
"Ryo",
""
]
] | We construct an asymmetric bouncing scenario within the VCDM model - also known as type-II minimally modified gravity -, a modified gravity theory with two local physical degrees of freedom. The scenario is exempt of any ghost or gradient instability, ad-hoc matching conditions or anisotropic stress issue (BKL instability). It moreover succeeds in generating the cosmological perturbations compatible with the observations. The scalar spectral index can be adapted by the choice of the equation of state of the matter sector and the form of the VCDM potential leading to an almost scale-invariant power spectrum. Satisfying the CMB bounds on the tensor-to-scalar ratio leads to a blue tensor spectrum. |
1508.01429 | Asoke Sen Dr. | Saswati Roy and A. K. Sen | Deflection of light ray due to a charged body using Material Medium
Approach | 15 pages, 7 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The gravitational deflection of light ray is an important prediction of
General Theory of Relativity. In this paper we develop analytical expression of
the deflection of light ray without any weak field approximation due to a
charged gravitational body represented by Reissner_Nordstr\"om (RN) and
Janis-Newman-Winicour (JNW) space time geometry, using material medium
approach. It is concluded that although both the geometries represent the
charged, non-rotating, spherically symmetric gravitating body, but the effect
of charge on the gravitational deflection is just opposite to each other. The
gravitational deflection decreases with charge in the RN geometry and increases
with charge in the JNW geometry. The calculations obtained here are compared
with other methods done by different authors. The formalism is applied to an
arbitrary selected pulsar PSRB1937+21 as a gravitating body, as a test case.
| [
{
"created": "Thu, 6 Aug 2015 15:14:31 GMT",
"version": "v1"
},
{
"created": "Fri, 8 Apr 2016 10:02:41 GMT",
"version": "v2"
},
{
"created": "Thu, 1 Jun 2017 18:18:48 GMT",
"version": "v3"
}
] | 2017-06-05 | [
[
"Roy",
"Saswati",
""
],
[
"Sen",
"A. K.",
""
]
] | The gravitational deflection of light ray is an important prediction of General Theory of Relativity. In this paper we develop analytical expression of the deflection of light ray without any weak field approximation due to a charged gravitational body represented by Reissner_Nordstr\"om (RN) and Janis-Newman-Winicour (JNW) space time geometry, using material medium approach. It is concluded that although both the geometries represent the charged, non-rotating, spherically symmetric gravitating body, but the effect of charge on the gravitational deflection is just opposite to each other. The gravitational deflection decreases with charge in the RN geometry and increases with charge in the JNW geometry. The calculations obtained here are compared with other methods done by different authors. The formalism is applied to an arbitrary selected pulsar PSRB1937+21 as a gravitating body, as a test case. |
gr-qc/9712018 | Shin'ji Mukouyama | Shinji Mukohyama, Masafumi Seriu and Hideo Kodama | Thermodynamics of entanglement in Schwarzschild spacetime | 27 pages, Latex file, 7 figures; revised to clarify our choice of the
state and to add references. Accepted for publication in Physical Review D | Phys.Rev. D58 (1998) 064001 | 10.1103/PhysRevD.58.064001 | YITP-97-63 | gr-qc | null | Extending the analysis in our previous paper, we construct the entanglement
thermodynamics for a massless scalar field on the Schwarzschild spacetime.
Contrary to the flat case, the entanglement energy $E_{ent}$ turns out to be
proportional to area radius of the boundary if it is near the horizon. This
peculiar behavior of $E_{ent}$ can be understood by the red-shift effect caused
by the curved background. Combined with the behavior of the entanglement
entropy, this result yields, quite surprisingly, the entanglement
thermodynamics of the same structure as the black hole thermodynamics. On the
basis of these results, we discuss the relevance of the concept of entanglement
as the microscopic origin of the black hole thermodynamics.
| [
{
"created": "Wed, 3 Dec 1997 02:25:01 GMT",
"version": "v1"
},
{
"created": "Fri, 5 Dec 1997 07:27:20 GMT",
"version": "v2"
},
{
"created": "Mon, 8 Dec 1997 02:54:06 GMT",
"version": "v3"
},
{
"created": "Wed, 10 Dec 1997 03:52:12 GMT",
"version": "v4"
},
{
"created": "Wed, 13 May 1998 10:18:16 GMT",
"version": "v5"
}
] | 2009-10-30 | [
[
"Mukohyama",
"Shinji",
""
],
[
"Seriu",
"Masafumi",
""
],
[
"Kodama",
"Hideo",
""
]
] | Extending the analysis in our previous paper, we construct the entanglement thermodynamics for a massless scalar field on the Schwarzschild spacetime. Contrary to the flat case, the entanglement energy $E_{ent}$ turns out to be proportional to area radius of the boundary if it is near the horizon. This peculiar behavior of $E_{ent}$ can be understood by the red-shift effect caused by the curved background. Combined with the behavior of the entanglement entropy, this result yields, quite surprisingly, the entanglement thermodynamics of the same structure as the black hole thermodynamics. On the basis of these results, we discuss the relevance of the concept of entanglement as the microscopic origin of the black hole thermodynamics. |
1802.03739 | Wen-Biao Han | Xiao-Jun Yue, Wen-Biao Han, Xian Chen | Dark matter: an efficient catalyst for intermediate-mass-ratio-inspiral
events | 17 pages, 10 figures | ApJ, 874: 34, 2019 | 10.3847/1538-4357/ab06f6 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational waves (GWs) can be produced if a stellar compact object, such
as a black hole (BH) or neutron star, inspirals into an intermediate-massive
black hole (IMBH) of $(10^3 \sim 10^5)\,M_\odot$. Such a system may be produced
in the center of a globular cluster (GC) or a nuclear star cluster (NSC), and
is known as an intermediate- or extreme-mass-ratio inspiral (IMRI or EMRI).
Motivated by the recent suggestions that dark matter minispikes could form
around IMBHs, we study the effect of dynamical friction against DM on the
merger rate of IMRIs/EMRIs. We find that the merger timescale of IMBHs with BHs
and NSs would be shortened by two to three orders of magnitude. As a result,
the event rate of IMRIs/EMRIs are enhanced by orders of magnitude relative to
that in the case of no DM minispikes. In the most extreme case where IMBHs are
small and the DM minispikes have a steep density profile, all the BH in GCs and
NSCs might be exhausted so that the mergers with NSs would dominate the current
IMRIs/EMRIs. Our results suggest that the mass function of the IMBHs below
$10^4 \,M_\odot$ would bear imprints of the distribution of DM minispikes
because these low-mass IMBHs can grow efficiently in the presence of DM
minispikes by merging with BHs and NSs. Future space-based GW detectors, like
LISA, Taiji, and Tianqin, can measure the IMRI/EMRI rate and hence constrain
the distribution of DM around IMBHs.
| [
{
"created": "Sun, 11 Feb 2018 13:48:29 GMT",
"version": "v1"
},
{
"created": "Mon, 1 Apr 2019 14:40:08 GMT",
"version": "v2"
}
] | 2019-04-02 | [
[
"Yue",
"Xiao-Jun",
""
],
[
"Han",
"Wen-Biao",
""
],
[
"Chen",
"Xian",
""
]
] | Gravitational waves (GWs) can be produced if a stellar compact object, such as a black hole (BH) or neutron star, inspirals into an intermediate-massive black hole (IMBH) of $(10^3 \sim 10^5)\,M_\odot$. Such a system may be produced in the center of a globular cluster (GC) or a nuclear star cluster (NSC), and is known as an intermediate- or extreme-mass-ratio inspiral (IMRI or EMRI). Motivated by the recent suggestions that dark matter minispikes could form around IMBHs, we study the effect of dynamical friction against DM on the merger rate of IMRIs/EMRIs. We find that the merger timescale of IMBHs with BHs and NSs would be shortened by two to three orders of magnitude. As a result, the event rate of IMRIs/EMRIs are enhanced by orders of magnitude relative to that in the case of no DM minispikes. In the most extreme case where IMBHs are small and the DM minispikes have a steep density profile, all the BH in GCs and NSCs might be exhausted so that the mergers with NSs would dominate the current IMRIs/EMRIs. Our results suggest that the mass function of the IMBHs below $10^4 \,M_\odot$ would bear imprints of the distribution of DM minispikes because these low-mass IMBHs can grow efficiently in the presence of DM minispikes by merging with BHs and NSs. Future space-based GW detectors, like LISA, Taiji, and Tianqin, can measure the IMRI/EMRI rate and hence constrain the distribution of DM around IMBHs. |
1506.09164 | Jedrzej \'Swie\.zewski | Norbert Bodendorfer, Jerzy Lewandowski, Jedrzej \'Swie\.zewski | General relativity in the radial gauge: Reduced phase space and
canonical structure | 23 pages, 1 figure; matches published version | Phys. Rev. D 92, 084041 (2015) | 10.1103/PhysRevD.92.084041 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Firstly, we present a reformulation of the standard canonical approach to
spherically symmetric systems in which the radial gauge is imposed. This is
done via the gauge unfixing technique, which serves as the exposition in the
context of the radial gauge. Secondly, we apply the same techniques to the full
theory, without assuming spherical symmetry, resulting in a reduced phase space
description of general relativity. The canonical structure of the theory is
analyzed.
| [
{
"created": "Tue, 30 Jun 2015 17:22:52 GMT",
"version": "v1"
},
{
"created": "Thu, 19 Nov 2015 10:18:00 GMT",
"version": "v2"
}
] | 2015-11-20 | [
[
"Bodendorfer",
"Norbert",
""
],
[
"Lewandowski",
"Jerzy",
""
],
[
"Świeżewski",
"Jedrzej",
""
]
] | Firstly, we present a reformulation of the standard canonical approach to spherically symmetric systems in which the radial gauge is imposed. This is done via the gauge unfixing technique, which serves as the exposition in the context of the radial gauge. Secondly, we apply the same techniques to the full theory, without assuming spherical symmetry, resulting in a reduced phase space description of general relativity. The canonical structure of the theory is analyzed. |
gr-qc/0202080 | T. Padmanabhan | T.Padmanabhan | Entropy and energy of a class of spacetimes with horizon: a general
derivation | revtex4; 3 pages | null | null | IUCAA preprint 06/2002 | gr-qc hep-th | null | Euclidean continuation of several Lorentzian spacetimes with horizons
requires treating the Euclidean time coordinate to be periodic with some period
$\beta$.
Such spacetimes (Schwarzschild, deSitter,Rindler .....) allow a temperature
$T=\beta^{-1}$ to be associated with the horizon. I construct a canonical
ensemble of a subclass of such spacetimes with a fixed value for $\beta$ and
evaluate the partition function $Z(\beta)$. For spherically symmetric
spacetimes with a horizon at r=a, the partition function has the generic form
$Z\propto \exp[S-\beta E]$, where $S= (1/4) 4\pi a^2$ and $|E|=(a/2)$. Both S
and E are determined entirely by the properties of the metric near the horizon.
This analysis reproduces the conventional result for the blackhole spacetimes
and provides a simple and consistent interpretation of entropy and energy for
deSitter spacetime. For the Rindler spacetime the entropy per unit transverse
area turns out to be (1/4) while the energy is zero. The implications are
discussed.
| [
{
"created": "Thu, 21 Feb 2002 16:36:40 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Padmanabhan",
"T.",
""
]
] | Euclidean continuation of several Lorentzian spacetimes with horizons requires treating the Euclidean time coordinate to be periodic with some period $\beta$. Such spacetimes (Schwarzschild, deSitter,Rindler .....) allow a temperature $T=\beta^{-1}$ to be associated with the horizon. I construct a canonical ensemble of a subclass of such spacetimes with a fixed value for $\beta$ and evaluate the partition function $Z(\beta)$. For spherically symmetric spacetimes with a horizon at r=a, the partition function has the generic form $Z\propto \exp[S-\beta E]$, where $S= (1/4) 4\pi a^2$ and $|E|=(a/2)$. Both S and E are determined entirely by the properties of the metric near the horizon. This analysis reproduces the conventional result for the blackhole spacetimes and provides a simple and consistent interpretation of entropy and energy for deSitter spacetime. For the Rindler spacetime the entropy per unit transverse area turns out to be (1/4) while the energy is zero. The implications are discussed. |
1708.08797 | Constantinos Skordis | Constantinos Skordis | Conditions for equivalence of static spherically symmetric spacetimes to
almost Friedman-Robertson-Walker | 12 pages | null | null | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We determine the conditions under which a static spherically symmetric
spacetime metric is equivalent to a perturbed Friedman-Robertson-Walker metric.
We construct the correspondence between the two metrics and discuss a simple
application.
| [
{
"created": "Tue, 29 Aug 2017 14:48:06 GMT",
"version": "v1"
}
] | 2017-08-30 | [
[
"Skordis",
"Constantinos",
""
]
] | We determine the conditions under which a static spherically symmetric spacetime metric is equivalent to a perturbed Friedman-Robertson-Walker metric. We construct the correspondence between the two metrics and discuss a simple application. |
1012.0908 | Stefan Hild | S. Hild, M. Abernathy, F. Acernese, P. Amaro-Seoane, N. Andersson, K.
Arun, F. Barone, B. Barr, M. Barsuglia, M. Beker, N. Beveridge, S.
Birindelli, S. Bose, L. Bosi, S. Braccini, C. Bradaschia, T. Bulik, E.
Calloni, G. Cella, E. Chassande Mottin, S. Chelkowski, A. Chincarini, J.
Clark, E. Coccia, C. Colacino, J. Colas, A. Cumming, L. Cunningham, E. Cuoco,
S. Danilishin, K. Danzmann, R. De Salvo, T. Dent, R. De Rosa, L. Di Fiore, A.
Di Virgilio, M. Doets, V. Fafone, P. Falferi, R. Flaminio, J. Franc, F.
Frasconi, A. Freise, D. Friedrich, P. Fulda, J. Gair, G. Gemme, E. Genin, A.
Gennai, A. Giazotto, K. Glampedakis, C. Gr\"af, M. Granata, H. Grote, G.
Guidi, A. Gurkovsky, G. Hammond, M. Hannam, J. Harms, D. Heinert, M. Hendry,
I. Heng, E. Hennes, J. Hough, S. Husa, S. Huttner, G. Jones, F. Khalili, K.
Kokeyama, K. Kokkotas, B. Krishnan, T.G.F. Li, M. Lorenzini, H. L\"uck, E.
Majorana, I. Mandel, V. Mandic, M. Mantovani, I. Martin, C. Michel, Y.
Minenkov, N. Morgado, S. Mosca, B Mours, H. M\"uller-Ebhardt, P. Murray, R.
Nawrodt, J. Nelson, R. Oshaughnessy, C. D. Ott, C. Palomba, A. Paoli, G.
Parguez, A. Pasqualetti, R. Passaquieti, D. Passuello, L. Pinard, W.
Plastino, R. Poggiani1, P. Popolizio, M. Prato, M. Punturo, P. Puppo, D.
Rabeling, P. Rapagnani, J. Read, T. Regimbau, H. Rehbein, S. Reid, F. Ricci,
F. Richard, A. Rocchi, S. Rowan, A. R\"udiger, L. Santamar\'ia, B. Sassolas,
B. Sathyaprakash, R. Schnabel, C. Schwarz, P. Seidel, A. Sintes, K. Somiya,
F. Speirits, K. Strain, S Strigin, P. Sutton, S. Tarabrin, A. Th\"uring, J.
van den Brand, M. van Veggel, C. van den Broeck, A. Vecchio, J. Veitch, F.
Vetrano, A. Vicere, S. Vyatchanin, B. Willke, G. Woan, K. Yamamoto | Sensitivity Studies for Third-Generation Gravitational Wave
Observatories | 13 pages, 7 pictures | null | 10.1088/0264-9381/28/9/094013 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Advanced gravitational wave detectors, currently under construction, are
expected to directly observe gravitational wave signals of astrophysical
origin. The Einstein Telescope, a third-generation gravitational wave detector,
has been proposed in order to fully open up the emerging field of gravitational
wave astronomy. In this article we describe sensitivity models for the Einstein
Telescope and investigate potential limits imposed by fundamental noise
sources. A special focus is set on evaluating the frequency band below 10Hz
where a complex mixture of seismic, gravity gradient, suspension thermal and
radiation pressure noise dominates. We develop the most accurate sensitivity
model, referred to as ET-D, for a third-generation detector so far, including
the most relevant fundamental noise contributions.
| [
{
"created": "Sat, 4 Dec 2010 12:17:06 GMT",
"version": "v1"
}
] | 2015-05-20 | [
[
"Hild",
"S.",
""
],
[
"Abernathy",
"M.",
""
],
[
"Acernese",
"F.",
""
],
[
"Amaro-Seoane",
"P.",
""
],
[
"Andersson",
"N.",
""
],
[
"Arun",
"K.",
""
],
[
"Barone",
"F.",
""
],
[
"Barr",
"B.",
""
],
[
"Barsuglia",
"M.",
""
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[
"Beker",
"M.",
""
],
[
"Beveridge",
"N.",
""
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[
"Birindelli",
"S.",
""
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[
"Bose",
"S.",
""
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[
"Bosi",
"L.",
""
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[
"Braccini",
"S.",
""
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[
"Bradaschia",
"C.",
""
],
[
"Bulik",
"T.",
""
],
[
"Calloni",
"E.",
""
],
[
"Cella",
"G.",
""
],
[
"Mottin",
"E. Chassande",
""
],
[
"Chelkowski",
"S.",
""
],
[
"Chincarini",
"A.",
""
],
[
"Clark",
"J.",
""
],
[
"Coccia",
"E.",
""
],
[
"Colacino",
"C.",
""
],
[
"Colas",
"J.",
""
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[
"Cumming",
"A.",
""
],
[
"Cunningham",
"L.",
""
],
[
"Cuoco",
"E.",
""
],
[
"Danilishin",
"S.",
""
],
[
"Danzmann",
"K.",
""
],
[
"De Salvo",
"R.",
""
],
[
"Dent",
"T.",
""
],
[
"De Rosa",
"R.",
""
],
[
"Di Fiore",
"L.",
""
],
[
"Di Virgilio",
"A.",
""
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[
"Doets",
"M.",
""
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[
"Fafone",
"V.",
""
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[
"Falferi",
"P.",
""
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[
"Flaminio",
"R.",
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[
"Franc",
"J.",
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[
"Frasconi",
"F.",
""
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[
"Freise",
"A.",
""
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[
"Friedrich",
"D.",
""
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[
"Fulda",
"P.",
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[
"Gair",
"J.",
""
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[
"Gemme",
"G.",
""
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[
"Genin",
"E.",
""
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[
"Gennai",
"A.",
""
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[
"Giazotto",
"A.",
""
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[
"Glampedakis",
"K.",
""
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[
"Gräf",
"C.",
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[
"Granata",
"M.",
""
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[
"Grote",
"H.",
""
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[
"Guidi",
"G.",
""
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[
"Gurkovsky",
"A.",
""
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[
"Hammond",
"G.",
""
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[
"Hannam",
"M.",
""
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[
"Harms",
"J.",
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[
"Heinert",
"D.",
""
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[
"Hendry",
"M.",
""
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[
"Heng",
"I.",
""
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[
"Hennes",
"E.",
""
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[
"Hough",
"J.",
""
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[
"Husa",
"S.",
""
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[
"Huttner",
"S.",
""
],
[
"Jones",
"G.",
""
],
[
"Khalili",
"F.",
""
],
[
"Kokeyama",
"K.",
""
],
[
"Kokkotas",
"K.",
""
],
[
"Krishnan",
"B.",
""
],
[
"Li",
"T. G. F.",
""
],
[
"Lorenzini",
"M.",
""
],
[
"Lück",
"H.",
""
],
[
"Majorana",
"E.",
""
],
[
"Mandel",
"I.",
""
],
[
"Mandic",
"V.",
""
],
[
"Mantovani",
"M.",
""
],
[
"Martin",
"I.",
""
],
[
"Michel",
"C.",
""
],
[
"Minenkov",
"Y.",
""
],
[
"Morgado",
"N.",
""
],
[
"Mosca",
"S.",
""
],
[
"Mours",
"B",
""
],
[
"Müller-Ebhardt",
"H.",
""
],
[
"Murray",
"P.",
""
],
[
"Nawrodt",
"R.",
""
],
[
"Nelson",
"J.",
""
],
[
"Oshaughnessy",
"R.",
""
],
[
"Ott",
"C. D.",
""
],
[
"Palomba",
"C.",
""
],
[
"Paoli",
"A.",
""
],
[
"Parguez",
"G.",
""
],
[
"Pasqualetti",
"A.",
""
],
[
"Passaquieti",
"R.",
""
],
[
"Passuello",
"D.",
""
],
[
"Pinard",
"L.",
""
],
[
"Plastino",
"W.",
""
],
[
"Poggiani1",
"R.",
""
],
[
"Popolizio",
"P.",
""
],
[
"Prato",
"M.",
""
],
[
"Punturo",
"M.",
""
],
[
"Puppo",
"P.",
""
],
[
"Rabeling",
"D.",
""
],
[
"Rapagnani",
"P.",
""
],
[
"Read",
"J.",
""
],
[
"Regimbau",
"T.",
""
],
[
"Rehbein",
"H.",
""
],
[
"Reid",
"S.",
""
],
[
"Ricci",
"F.",
""
],
[
"Richard",
"F.",
""
],
[
"Rocchi",
"A.",
""
],
[
"Rowan",
"S.",
""
],
[
"Rüdiger",
"A.",
""
],
[
"Santamaría",
"L.",
""
],
[
"Sassolas",
"B.",
""
],
[
"Sathyaprakash",
"B.",
""
],
[
"Schnabel",
"R.",
""
],
[
"Schwarz",
"C.",
""
],
[
"Seidel",
"P.",
""
],
[
"Sintes",
"A.",
""
],
[
"Somiya",
"K.",
""
],
[
"Speirits",
"F.",
""
],
[
"Strain",
"K.",
""
],
[
"Strigin",
"S",
""
],
[
"Sutton",
"P.",
""
],
[
"Tarabrin",
"S.",
""
],
[
"Thüring",
"A.",
""
],
[
"Brand",
"J. van den",
""
],
[
"van Veggel",
"M.",
""
],
[
"Broeck",
"C. van den",
""
],
[
"Vecchio",
"A.",
""
],
[
"Veitch",
"J.",
""
],
[
"Vetrano",
"F.",
""
],
[
"Vicere",
"A.",
""
],
[
"Vyatchanin",
"S.",
""
],
[
"Willke",
"B.",
""
],
[
"Woan",
"G.",
""
],
[
"Yamamoto",
"K.",
""
]
] | Advanced gravitational wave detectors, currently under construction, are expected to directly observe gravitational wave signals of astrophysical origin. The Einstein Telescope, a third-generation gravitational wave detector, has been proposed in order to fully open up the emerging field of gravitational wave astronomy. In this article we describe sensitivity models for the Einstein Telescope and investigate potential limits imposed by fundamental noise sources. A special focus is set on evaluating the frequency band below 10Hz where a complex mixture of seismic, gravity gradient, suspension thermal and radiation pressure noise dominates. We develop the most accurate sensitivity model, referred to as ET-D, for a third-generation detector so far, including the most relevant fundamental noise contributions. |
gr-qc/0305097 | Carl E. Dolby | Carl E. Dolby | Simultaneity and the Concept of `Particle' | Submitted to World Scientific. To appear in proceedings of the Venice
Conference on Time and Matter, August 2002 | null | null | null | gr-qc hep-th | null | The history of the particle concept is briefly reviewed, with particular
emphasis on the `foliation dependence' of many particle creation models, and
the possible connection between our notion of particle and our notion of
simultaneity. It is argued that the concept of `radar time' (originally
introduced by Sir Hermann Bondi in his work on k-calculus) provides a
satisfactory concept of `simultaneity' for observers in curved spacetimes. This
is used to propose an observer-dependent particle interpretation, applicable to
an arbitrary observer, depending solely on that observers motion and not on a
choice of coordinates or gauge. This definition is illustrated with application
to non-inertial observers and simple cosmologies, demonstrating its generality
and its consistency with known cases.
| [
{
"created": "Tue, 27 May 2003 11:36:46 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Dolby",
"Carl E.",
""
]
] | The history of the particle concept is briefly reviewed, with particular emphasis on the `foliation dependence' of many particle creation models, and the possible connection between our notion of particle and our notion of simultaneity. It is argued that the concept of `radar time' (originally introduced by Sir Hermann Bondi in his work on k-calculus) provides a satisfactory concept of `simultaneity' for observers in curved spacetimes. This is used to propose an observer-dependent particle interpretation, applicable to an arbitrary observer, depending solely on that observers motion and not on a choice of coordinates or gauge. This definition is illustrated with application to non-inertial observers and simple cosmologies, demonstrating its generality and its consistency with known cases. |
2205.00298 | Adri\'an Del R\'io Vega | Abhay Ashtekar, Adri\'an del R\'io, Marc Schneider | Space-like Singularities of General Relativity: A Phantom menace? | Invited article under "Introduction to Current Research", GRG (at
press). Special issue in memory of Prof. T. Padmanabhan | Gen. Relativ.Grav. (2022) 54:45 | 10.1007/s10714-022-02932-5 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The big bang and the Schwarzschild singularities are space-like. They are
generally regarded as the "final frontiers" at which space-time ends and
general relativity breaks down. We review the status of such space-like
singularities from three increasingly more general perspectives. They are
provided by (i) A reformulation of classical general relativity motivated by
the Belinskii, Khalatnikov, Lifshitz conjecture on the behavior of the
gravitational field near space-like singularities; (ii) The use of test quantum
fields to probe the nature of these singularities; and, (iii) An analysis of
the fate of these singularities in loop quantum gravity due to quantum geometry
effects. At all three levels singularities turn out to be less menacing than
one might a priori expect from classical general relativity. Our goal is to
present an overview of the emerging conceptual picture and suggest lines for
further work. In line with the \emph{Introduction to Current Research} theme,
we have made an attempt to make it easily accessible to all researchers in
gravitational physics.
| [
{
"created": "Sat, 30 Apr 2022 16:00:27 GMT",
"version": "v1"
}
] | 2022-05-24 | [
[
"Ashtekar",
"Abhay",
""
],
[
"del Río",
"Adrián",
""
],
[
"Schneider",
"Marc",
""
]
] | The big bang and the Schwarzschild singularities are space-like. They are generally regarded as the "final frontiers" at which space-time ends and general relativity breaks down. We review the status of such space-like singularities from three increasingly more general perspectives. They are provided by (i) A reformulation of classical general relativity motivated by the Belinskii, Khalatnikov, Lifshitz conjecture on the behavior of the gravitational field near space-like singularities; (ii) The use of test quantum fields to probe the nature of these singularities; and, (iii) An analysis of the fate of these singularities in loop quantum gravity due to quantum geometry effects. At all three levels singularities turn out to be less menacing than one might a priori expect from classical general relativity. Our goal is to present an overview of the emerging conceptual picture and suggest lines for further work. In line with the \emph{Introduction to Current Research} theme, we have made an attempt to make it easily accessible to all researchers in gravitational physics. |
2207.12438 | Sean Li | Sean E. Li, Thomas W. Baumgarte, Kenneth A. Dennison, and H. P. de
Oliveira | Bona-Mass\'o slices of Reissner-Nordstr\"om spacetimes | 9 pages, 10 figures | Phys. Rev. D 106, 104059 (2022) | 10.1103/PhysRevD.106.104059 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Motivated by recent numerical relativity simulations of charged black holes
and their interactions, we explore the properties of common slicing conditions
in Reissner-Nordstr\"om spacetimes. Specifically, we consider different choices
for the so-called Bona-Mass\'o function, and construct static and spherically
symmetric slices of the Reissner-Nordstr\"om spacetime satisfying the
corresponding slicing conditions. For some of these functions the construction
is entirely analytical, while for others we use numerical root-finding to solve
quartic equations. Our solutions are parameterized by the charge-to-mass ratio
$\lambda = Q/M$ and approach a unique slice, independent of the Bona-Mass\'o
functions considered here, in the extremal limit $\lambda \to 1$.
| [
{
"created": "Mon, 25 Jul 2022 18:00:26 GMT",
"version": "v1"
},
{
"created": "Wed, 11 Jan 2023 15:30:06 GMT",
"version": "v2"
}
] | 2023-01-12 | [
[
"Li",
"Sean E.",
""
],
[
"Baumgarte",
"Thomas W.",
""
],
[
"Dennison",
"Kenneth A.",
""
],
[
"de Oliveira",
"H. P.",
""
]
] | Motivated by recent numerical relativity simulations of charged black holes and their interactions, we explore the properties of common slicing conditions in Reissner-Nordstr\"om spacetimes. Specifically, we consider different choices for the so-called Bona-Mass\'o function, and construct static and spherically symmetric slices of the Reissner-Nordstr\"om spacetime satisfying the corresponding slicing conditions. For some of these functions the construction is entirely analytical, while for others we use numerical root-finding to solve quartic equations. Our solutions are parameterized by the charge-to-mass ratio $\lambda = Q/M$ and approach a unique slice, independent of the Bona-Mass\'o functions considered here, in the extremal limit $\lambda \to 1$. |
gr-qc/0307118 | Carlo Rovelli | Florian Conrady, Luisa Doplicher, Robert Oeckl, Carlo Rovelli, Massimo
Testa | Minkowski vacuum in background independent quantum gravity | 8 pages, no figures | Phys.Rev. D69 (2004) 064019 | 10.1103/PhysRevD.69.064019 | ROMA1-2003-1539, AEI-2003-063 | gr-qc | null | We consider a local formalism in quantum field theory, in which no reference
is made to infinitely extended spacial surfaces, infinite past or infinite
future. This can be obtained in terms of a functional W[f,S] of the field f on
a closed 3d surface S that bounds a finite region R of Minkowski spacetime. The
dependence of W on S is governed by a local covariant generalization of the
Schroedinger equation. Particles' scattering amplitudes that describe
experiments conducted in the finite region R --the lab during a finite time--
can be expressed in terms of W. The dependence of W on the geometry of S
expresses the dependence of the transition amplitudes on the relative location
of the particle detectors. In a gravitational theory, background independence
implies that W is independent from S. However, the detectors' relative location
is still coded in the argument of W, because the geometry of the boundary
surface is determined by the boundary value f of the gravitational field. This
observation clarifies the physical meaning of the functional W defined by non
perturbative formulations of quantum gravity, such as the spinfoam formalism.
In particular, it suggests a way to derive particles' scattering amplitudes
from a spinfoam model. In particular, we discuss the notion of vacuum in a
generally covariant context. We distinguish the nonperturbative vacuum |0_S>,
which codes the dynamics, from the Minkowski vacuum |0_M>, which is the state
with no particles and is recovered by taking appropriate large values of the
boundary metric. We derive a relation between the two vacuum states. We propose
an explicit expression for computing the Minkowski vacuum from a spinfoam
model.
| [
{
"created": "Wed, 30 Jul 2003 12:32:14 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Conrady",
"Florian",
""
],
[
"Doplicher",
"Luisa",
""
],
[
"Oeckl",
"Robert",
""
],
[
"Rovelli",
"Carlo",
""
],
[
"Testa",
"Massimo",
""
]
] | We consider a local formalism in quantum field theory, in which no reference is made to infinitely extended spacial surfaces, infinite past or infinite future. This can be obtained in terms of a functional W[f,S] of the field f on a closed 3d surface S that bounds a finite region R of Minkowski spacetime. The dependence of W on S is governed by a local covariant generalization of the Schroedinger equation. Particles' scattering amplitudes that describe experiments conducted in the finite region R --the lab during a finite time-- can be expressed in terms of W. The dependence of W on the geometry of S expresses the dependence of the transition amplitudes on the relative location of the particle detectors. In a gravitational theory, background independence implies that W is independent from S. However, the detectors' relative location is still coded in the argument of W, because the geometry of the boundary surface is determined by the boundary value f of the gravitational field. This observation clarifies the physical meaning of the functional W defined by non perturbative formulations of quantum gravity, such as the spinfoam formalism. In particular, it suggests a way to derive particles' scattering amplitudes from a spinfoam model. In particular, we discuss the notion of vacuum in a generally covariant context. We distinguish the nonperturbative vacuum |0_S>, which codes the dynamics, from the Minkowski vacuum |0_M>, which is the state with no particles and is recovered by taking appropriate large values of the boundary metric. We derive a relation between the two vacuum states. We propose an explicit expression for computing the Minkowski vacuum from a spinfoam model. |
1211.3289 | \"Ozg\"ur Acik | \"Umit Ertem, \"Ozg\"ur A\c{c}{\i}k | Couplings of gravitational currents with Chern-Simons gravities | 8 pages, a new discussion with two paragraphs and some references
added, published version | Phys. Rev. D 87, 044052 (2013) | 10.1103/PhysRevD.87.044052 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The coupling of conserved p-brane currents with non-Abelian gaugetheories is
done consistently by using Chern-Simons forms. Conserved currents localized on
p-branes that have a gravitational origin can be constructed from Killing-Yano
forms of the underlying spacetime. We propose a generalization of the coupling
procedure with Chern-Simons gravities to the case of gravitational conserved
currents. In odd dimensions, the field equations of coupled Chern-Simons
gravities that describe the local curvature on p-branes are obtained. In
special cases of three and five dimensions, the field equations are
investigated in detail.
| [
{
"created": "Wed, 14 Nov 2012 12:27:52 GMT",
"version": "v1"
},
{
"created": "Thu, 28 Feb 2013 19:05:45 GMT",
"version": "v2"
}
] | 2015-06-12 | [
[
"Ertem",
"Ümit",
""
],
[
"Açık",
"Özgür",
""
]
] | The coupling of conserved p-brane currents with non-Abelian gaugetheories is done consistently by using Chern-Simons forms. Conserved currents localized on p-branes that have a gravitational origin can be constructed from Killing-Yano forms of the underlying spacetime. We propose a generalization of the coupling procedure with Chern-Simons gravities to the case of gravitational conserved currents. In odd dimensions, the field equations of coupled Chern-Simons gravities that describe the local curvature on p-branes are obtained. In special cases of three and five dimensions, the field equations are investigated in detail. |
1406.2397 | Hongwei Yu | Qinglin Li, Hongwei Yu, Wenting Zhou | Response of a uniformly accelerated detector to massless
Rarita-Schwinger fields in vacuum | 12 pages, no figures | Annals of Physics 348 (2014) 144 | 10.1016/j.aop.2014.05.016 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the response of a uniformly accelerated detector modeled by a
two-level atom nonlinearly coupled to vacuum massless Rarita-Schwinger fields.
We first generalize the formalism developed by Dalibard, Dupont-Roc, and
Cohen-Tannoudji in the linear coupling case, and we then calculate the mean
rate of change of the atomic energy of the accelerated atom. Our result shows
that a uniformly accelerated atom in its ground state interacting with vacuum
Rarita-Schwinger field fluctuations would spontaneously transition to an
excited state and the unique feature in contrast to the case of the atom
coupled to the scalar, electromagnetic and Dirac fields is the appearance of
terms in the excitation rate which are proportional to the sixth and eighth
powers of acceleration.
| [
{
"created": "Tue, 10 Jun 2014 01:00:16 GMT",
"version": "v1"
}
] | 2015-06-19 | [
[
"Li",
"Qinglin",
""
],
[
"Yu",
"Hongwei",
""
],
[
"Zhou",
"Wenting",
""
]
] | We study the response of a uniformly accelerated detector modeled by a two-level atom nonlinearly coupled to vacuum massless Rarita-Schwinger fields. We first generalize the formalism developed by Dalibard, Dupont-Roc, and Cohen-Tannoudji in the linear coupling case, and we then calculate the mean rate of change of the atomic energy of the accelerated atom. Our result shows that a uniformly accelerated atom in its ground state interacting with vacuum Rarita-Schwinger field fluctuations would spontaneously transition to an excited state and the unique feature in contrast to the case of the atom coupled to the scalar, electromagnetic and Dirac fields is the appearance of terms in the excitation rate which are proportional to the sixth and eighth powers of acceleration. |
2011.01326 | Sarah Kahlen | Jose Luis Bl\'azquez-Salcedo, Sarah Kahlen, Jutta Kunz | Critical solutions of scalarized black holes | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider charged black holes with scalar hair obtained in a class of
Einstein-Maxwell-scalar models, where the scalar field is coupled to the
Maxwell invariant with a quartic coupling function. Besides the
Reissner-Nordstr\"om black holes, these models allow for black holes with
scalar hair. Scrutinizing the domain of existence of these hairy black holes,
we observe a critical behavior: A limiting configuration is encountered at a
critical value of the charge, where spacetime splits into two parts: an inner
spacetime with a finite scalar field and an outer extremal Reissner-Nordstr\"om
spacetime. Such a pattern was first observed in the context of gravitating
non-Abelian magnetic monopoles and their hairy black holes.
| [
{
"created": "Mon, 2 Nov 2020 21:14:22 GMT",
"version": "v1"
}
] | 2020-11-04 | [
[
"Blázquez-Salcedo",
"Jose Luis",
""
],
[
"Kahlen",
"Sarah",
""
],
[
"Kunz",
"Jutta",
""
]
] | We consider charged black holes with scalar hair obtained in a class of Einstein-Maxwell-scalar models, where the scalar field is coupled to the Maxwell invariant with a quartic coupling function. Besides the Reissner-Nordstr\"om black holes, these models allow for black holes with scalar hair. Scrutinizing the domain of existence of these hairy black holes, we observe a critical behavior: A limiting configuration is encountered at a critical value of the charge, where spacetime splits into two parts: an inner spacetime with a finite scalar field and an outer extremal Reissner-Nordstr\"om spacetime. Such a pattern was first observed in the context of gravitating non-Abelian magnetic monopoles and their hairy black holes. |
1307.4158 | Drew Keppel | Drew Keppel | Metrics for multi-detector template placement in searches for
short-duration nonprecessing inspiral gravitational-wave signals | 10 pages, 5 figures | null | null | LIGO-P1300084 | gr-qc astro-ph.IM physics.data-an | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using the family of multi-detector F-statistic metrics for short duration,
nonprecessing inspiral signals, we derive a marginalized metric that is
directly applicable to the problem of generating template banks for coincident
and coherent multi-detector searches for gravitational-waves. This metric is
compared to other average metrics, such as that proposed for the case of
searches associated with continuous signals from rotating neutron stars. We
show how the four-dimensional metric can be separated into two two-dimensional
metrics associated with the sky and mass parameter subspaces, allowing the
creation of separate template banks for these subspaces. Finally, we present an
algorithm for computing the mass space metric associated with both coincident
and coherent multi-detector targeted or all-sky searches for short duration,
nonprecessing inspiral gravitational-wave signals.
| [
{
"created": "Tue, 16 Jul 2013 04:09:48 GMT",
"version": "v1"
}
] | 2013-07-17 | [
[
"Keppel",
"Drew",
""
]
] | Using the family of multi-detector F-statistic metrics for short duration, nonprecessing inspiral signals, we derive a marginalized metric that is directly applicable to the problem of generating template banks for coincident and coherent multi-detector searches for gravitational-waves. This metric is compared to other average metrics, such as that proposed for the case of searches associated with continuous signals from rotating neutron stars. We show how the four-dimensional metric can be separated into two two-dimensional metrics associated with the sky and mass parameter subspaces, allowing the creation of separate template banks for these subspaces. Finally, we present an algorithm for computing the mass space metric associated with both coincident and coherent multi-detector targeted or all-sky searches for short duration, nonprecessing inspiral gravitational-wave signals. |
1902.08037 | Pritikana Bhandari | Subhayan Maity, Pritikana Bhandari, Subenoy Chakraborty | Universe consisting of diffusive dark fluids: thermodynamics and
stability analysis | null | European Physical Journal C79(2019) no.1,82 | 10.1140/epjc/s10052-019-6603-0 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The present work deals with homogeneous and isotropic FLRW model of the
Universe having a system of non-interacting diffusive cosmic fluids with
barotropic equation of state (constant or variable equation of state
parameter). Due to diffusive nature of the cosmic fluids, the divergence of the
energy momentum tensor is chosen to be proportional to the diffusive current.
The thermodynamic stability analysis of individual fluids is done and the
stability conditions are expressed as restrictions on the equation of state
parameter.
| [
{
"created": "Tue, 19 Feb 2019 05:45:43 GMT",
"version": "v1"
}
] | 2019-02-22 | [
[
"Maity",
"Subhayan",
""
],
[
"Bhandari",
"Pritikana",
""
],
[
"Chakraborty",
"Subenoy",
""
]
] | The present work deals with homogeneous and isotropic FLRW model of the Universe having a system of non-interacting diffusive cosmic fluids with barotropic equation of state (constant or variable equation of state parameter). Due to diffusive nature of the cosmic fluids, the divergence of the energy momentum tensor is chosen to be proportional to the diffusive current. The thermodynamic stability analysis of individual fluids is done and the stability conditions are expressed as restrictions on the equation of state parameter. |
2403.16229 | Dawood Kothawala Dr. | Dawood Kothawala | Non-Inertial Rigid Frames and the Principle of Equivalence | 7 pages, 2 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | One version of the principle of equivalence, as originally formulated by
Einstein, states that ``gravity" can be mimicked locally by going to an
``accelerated frame of reference". As highlighted by Synge, the physical
content of this principle remains obscure in so far as it does not refer to the
Riemann tensor $R_{abcd}$, which encodes the true effects of gravity. We here
give the acceleration profile of a $Born$ rigid, Rindler$esque$, frame that can
mimic a gravitational field corresponding to a given $R_{abcd}$. The
generalised deviation equation that yields this result also has Centrifugal and
Coriolis terms appearing in a purely relational context, yielding a similar
connection between angular velocity of rotating, rigid inertial frames and the
Riemann tensor. We comment briefly on implications for Mach principle.
| [
{
"created": "Sun, 24 Mar 2024 16:47:54 GMT",
"version": "v1"
}
] | 2024-03-26 | [
[
"Kothawala",
"Dawood",
""
]
] | One version of the principle of equivalence, as originally formulated by Einstein, states that ``gravity" can be mimicked locally by going to an ``accelerated frame of reference". As highlighted by Synge, the physical content of this principle remains obscure in so far as it does not refer to the Riemann tensor $R_{abcd}$, which encodes the true effects of gravity. We here give the acceleration profile of a $Born$ rigid, Rindler$esque$, frame that can mimic a gravitational field corresponding to a given $R_{abcd}$. The generalised deviation equation that yields this result also has Centrifugal and Coriolis terms appearing in a purely relational context, yielding a similar connection between angular velocity of rotating, rigid inertial frames and the Riemann tensor. We comment briefly on implications for Mach principle. |
0710.1763 | Chih-Hung Wang | Chih-Hung Wang | Linearized Torsion Waves in a Tensor-Tensor Theory of Gravity | 13 pages | Annales de la Fondation Louis de Broglie, Volume 32 no 2-3, 267,
2007 | null | null | gr-qc | null | We investigate a linearized tensor-tensor theory of gravity with torsion and
a perturbed torsion wave solution is discovered in background Minkowski
spacetime with zero torsion. Furthermore, gauge transformations of any
perturbed tensor field are derived in general background non-Riemannian
geometries. By calculating autoparallel deviations, both longitudinal and
transverse polarizations of the torsion wave are discovered.
| [
{
"created": "Tue, 9 Oct 2007 13:22:53 GMT",
"version": "v1"
},
{
"created": "Wed, 12 Dec 2007 05:30:39 GMT",
"version": "v2"
}
] | 2008-07-02 | [
[
"Wang",
"Chih-Hung",
""
]
] | We investigate a linearized tensor-tensor theory of gravity with torsion and a perturbed torsion wave solution is discovered in background Minkowski spacetime with zero torsion. Furthermore, gauge transformations of any perturbed tensor field are derived in general background non-Riemannian geometries. By calculating autoparallel deviations, both longitudinal and transverse polarizations of the torsion wave are discovered. |
2307.16305 | Deng Wang | Deng Wang | Testing the first law of black hole mechanics with GW150914 | 3 pgs, 2 figs. This study gives a possible evidence of 1st law of BH
mechanics | null | null | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Whether the first law of black hole mechanics is correct is an important
question in black holes physics. Subjected to current limited gravitational
wave events, we propose its weaker version that permits a relatively large
perturbation to a black hole system and implement a simple test with the first
event GW150914. Confronting the strain data with the theory, we obtain the
constraint on the deviation parameter $\alpha=0.07\pm0.11$, which indicates
that this weaker version is valid at the 68\% confidence level. This result
implies that the first law of black hole mechanics may be correct.
| [
{
"created": "Sun, 30 Jul 2023 19:24:41 GMT",
"version": "v1"
},
{
"created": "Tue, 1 Aug 2023 12:24:59 GMT",
"version": "v2"
}
] | 2023-08-02 | [
[
"Wang",
"Deng",
""
]
] | Whether the first law of black hole mechanics is correct is an important question in black holes physics. Subjected to current limited gravitational wave events, we propose its weaker version that permits a relatively large perturbation to a black hole system and implement a simple test with the first event GW150914. Confronting the strain data with the theory, we obtain the constraint on the deviation parameter $\alpha=0.07\pm0.11$, which indicates that this weaker version is valid at the 68\% confidence level. This result implies that the first law of black hole mechanics may be correct. |
1110.1659 | Christian Corda cordac | Lawrence B. Crowell and Christian Corda | f(R) Gravity, relic coherent gravitons and optical chaos | 32 pages, 1 figure, invited paper to appear in "Beyond Standard
Gravity and Cosmology", special issue of "Galaxies" edited by Antonaldo
Diaferio | Galaxies 2014, 2(1), 160-188 | 10.3390/galaxies2010160 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss the production of massive relic coherent gravitons in a particular
class of f(R) gravity which arises from string theory and their possible
imprint in Cosmic Microwave Background. In fact, in the very early universe
these relic gravitons could have acted as slow gravity waves. They may have
then acted to focus the geodesics of radiation and matter. Therefore, their
imprint on the later evolution of the universe could appear as filaments and
domain wall in the Universe today. In that case, the effect on Cosmic Microwave
Background should be analogous to the effect of water waves, which, in focusing
light, create optical caustics which are commonly seen on the bottom of
swimming pools. We analyze this important issue by showing how relic massive
GWs perturb the trajectories of Cosmic Microwave Background photons
(gravitational lensing by relic GWs). The consequence of the type of physics
discussed is outlined by illustrating an amplification of what might be called
optical chaos.
| [
{
"created": "Sat, 8 Oct 2011 18:41:19 GMT",
"version": "v1"
},
{
"created": "Thu, 17 Nov 2011 06:29:22 GMT",
"version": "v2"
},
{
"created": "Wed, 19 Feb 2014 09:32:05 GMT",
"version": "v3"
}
] | 2015-03-19 | [
[
"Crowell",
"Lawrence B.",
""
],
[
"Corda",
"Christian",
""
]
] | We discuss the production of massive relic coherent gravitons in a particular class of f(R) gravity which arises from string theory and their possible imprint in Cosmic Microwave Background. In fact, in the very early universe these relic gravitons could have acted as slow gravity waves. They may have then acted to focus the geodesics of radiation and matter. Therefore, their imprint on the later evolution of the universe could appear as filaments and domain wall in the Universe today. In that case, the effect on Cosmic Microwave Background should be analogous to the effect of water waves, which, in focusing light, create optical caustics which are commonly seen on the bottom of swimming pools. We analyze this important issue by showing how relic massive GWs perturb the trajectories of Cosmic Microwave Background photons (gravitational lensing by relic GWs). The consequence of the type of physics discussed is outlined by illustrating an amplification of what might be called optical chaos. |
1106.3031 | Felipe Poulis | F. P. Poulis and J. M. Salim | Weyl Geometry as Characterization of Space-Time | 12 pages | Int. J. Mod. Phys.: Conf. Series, V. 3, 87-97 (2011) | 10.1142/S2010194511001176 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Motivated by an axiomatic approach to characterize space-time it is
investigated a reformulation of Einstein's gravity where the pseudo-riemannian
geometry is substituted by a Weyl one. It is presented the main properties of
the Weyl geometry and it is shown that it gives extra contributions to the
trajectories of test particles, serving as one more motivation to study general
relativity in Weyl geometry. It is introduced its variational formalism and it
is established the coupling with other physical fields in such a way that the
theory acquires a gauge symmetry for the geometrical fields. It is shown that
this symmetry is still present for the red-shift and it is concluded that for
cosmological models it opens the possibility that observations can be fully
described by the new geometrical scalar field. It is concluded then that this
reformulation, although representing a theoretical advance, still needs a
complete description of their objects.
| [
{
"created": "Wed, 15 Jun 2011 17:30:30 GMT",
"version": "v1"
},
{
"created": "Thu, 15 Dec 2011 21:26:32 GMT",
"version": "v2"
}
] | 2011-12-19 | [
[
"Poulis",
"F. P.",
""
],
[
"Salim",
"J. M.",
""
]
] | Motivated by an axiomatic approach to characterize space-time it is investigated a reformulation of Einstein's gravity where the pseudo-riemannian geometry is substituted by a Weyl one. It is presented the main properties of the Weyl geometry and it is shown that it gives extra contributions to the trajectories of test particles, serving as one more motivation to study general relativity in Weyl geometry. It is introduced its variational formalism and it is established the coupling with other physical fields in such a way that the theory acquires a gauge symmetry for the geometrical fields. It is shown that this symmetry is still present for the red-shift and it is concluded that for cosmological models it opens the possibility that observations can be fully described by the new geometrical scalar field. It is concluded then that this reformulation, although representing a theoretical advance, still needs a complete description of their objects. |
2010.02023 | Luigi Pilo | Marco Celoria, Denis Comelli, Luigi Pilo, Rocco Rollo | Boosting GWs in Supersolid Inflation | 32 pages, 8 figures. Few typos corrected and comments added | null | 10.1007/JHEP01(2021)185 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Inflation driven by a generic self-gravitating medium is an interesting
alternative to study the impact of spontaneous spacetime symmetry breaking
during a quasi de-Sitter phase, in particular the 4-dimensional diffeomorphism
invariance of GR is spontaneously broken down to $ISO(3)$. The effective
description is based on four scalar fields that describe the excitations of a
supersolid. There are two phonon-like propagating scalar degrees of freedom
that mix non-trivially both at early and late times and, after exiting the
horizon, give rise to non-trivial correlations among the different scalar power
spectra. The non-linear structure of the theory allows a secondary
gravitational waves production during inflation, efficient enough to saturate
the present experimental bound and with a blue-tilted spectral index.
| [
{
"created": "Fri, 2 Oct 2020 10:54:56 GMT",
"version": "v1"
},
{
"created": "Thu, 10 Dec 2020 13:27:47 GMT",
"version": "v2"
}
] | 2021-02-24 | [
[
"Celoria",
"Marco",
""
],
[
"Comelli",
"Denis",
""
],
[
"Pilo",
"Luigi",
""
],
[
"Rollo",
"Rocco",
""
]
] | Inflation driven by a generic self-gravitating medium is an interesting alternative to study the impact of spontaneous spacetime symmetry breaking during a quasi de-Sitter phase, in particular the 4-dimensional diffeomorphism invariance of GR is spontaneously broken down to $ISO(3)$. The effective description is based on four scalar fields that describe the excitations of a supersolid. There are two phonon-like propagating scalar degrees of freedom that mix non-trivially both at early and late times and, after exiting the horizon, give rise to non-trivial correlations among the different scalar power spectra. The non-linear structure of the theory allows a secondary gravitational waves production during inflation, efficient enough to saturate the present experimental bound and with a blue-tilted spectral index. |
gr-qc/0303072 | Martin Bojowald | Martin Bojowald and Kevin Vandersloot | Loop Quantum Cosmology, Boundary Proposals, and Inflation | 20 pages, 6 figures | Phys.Rev. D67 (2003) 124023 | 10.1103/PhysRevD.67.124023 | CGPG-03/3-4 | gr-qc astro-ph hep-th | null | Loop quantum cosmology of the closed isotropic model is studied with a
special emphasis on a comparison with traditional results obtained in the
Wheeler-DeWitt approach. This includes the relation of the dynamical initial
conditions with boundary conditions such as the no-boundary or the tunneling
proposal and a discussion of inflation from quantum cosmology.
| [
{
"created": "Wed, 19 Mar 2003 18:52:19 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Bojowald",
"Martin",
""
],
[
"Vandersloot",
"Kevin",
""
]
] | Loop quantum cosmology of the closed isotropic model is studied with a special emphasis on a comparison with traditional results obtained in the Wheeler-DeWitt approach. This includes the relation of the dynamical initial conditions with boundary conditions such as the no-boundary or the tunneling proposal and a discussion of inflation from quantum cosmology. |
0907.5197 | Adam Pound | Adam Pound | The self-consistent gravitational self-force | 44 pages, 4 figures | Phys.Rev.D81:024023,2010 | 10.1103/PhysRevD.81.024023 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | I review the problem of motion for small bodies in General Relativity, with
an emphasis on developing a self-consistent treatment of the gravitational
self-force. An analysis of the various derivations extant in the literature
leads me to formulate an asymptotic expansion in which the metric is expanded
while a representative worldline is held fixed; I discuss the utility of this
expansion for both exact point particles and asymptotically small bodies,
contrasting it with a regular expansion in which both the metric and the
worldline are expanded. Based on these preliminary analyses, I present a
general method of deriving self-consistent equations of motion for arbitrarily
structured (sufficiently compact) small bodies. My method utilizes two
expansions: an inner expansion that keeps the size of the body fixed, and an
outer expansion that lets the body shrink while holding its worldline fixed. By
imposing the Lorenz gauge, I express the global solution to the Einstein
equation in the outer expansion in terms of an integral over a worldtube of
small radius surrounding the body. Appropriate boundary data on the tube are
determined from a local-in-space expansion in a buffer region where both the
inner and outer expansions are valid. This buffer-region expansion also results
in an expression for the self-force in terms of irreducible pieces of the
metric perturbation on the worldline. Based on the global solution, these
pieces of the perturbation can be written in terms of a tail integral over the
body's past history. This approach can be applied at any order to obtain a
self-consistent approximation that is valid on long timescales, both near and
far from the small body. I conclude by discussing possible extensions of my
method and comparing it to alternative approaches.
| [
{
"created": "Wed, 29 Jul 2009 19:51:52 GMT",
"version": "v1"
},
{
"created": "Wed, 21 Oct 2009 16:13:10 GMT",
"version": "v2"
}
] | 2010-04-06 | [
[
"Pound",
"Adam",
""
]
] | I review the problem of motion for small bodies in General Relativity, with an emphasis on developing a self-consistent treatment of the gravitational self-force. An analysis of the various derivations extant in the literature leads me to formulate an asymptotic expansion in which the metric is expanded while a representative worldline is held fixed; I discuss the utility of this expansion for both exact point particles and asymptotically small bodies, contrasting it with a regular expansion in which both the metric and the worldline are expanded. Based on these preliminary analyses, I present a general method of deriving self-consistent equations of motion for arbitrarily structured (sufficiently compact) small bodies. My method utilizes two expansions: an inner expansion that keeps the size of the body fixed, and an outer expansion that lets the body shrink while holding its worldline fixed. By imposing the Lorenz gauge, I express the global solution to the Einstein equation in the outer expansion in terms of an integral over a worldtube of small radius surrounding the body. Appropriate boundary data on the tube are determined from a local-in-space expansion in a buffer region where both the inner and outer expansions are valid. This buffer-region expansion also results in an expression for the self-force in terms of irreducible pieces of the metric perturbation on the worldline. Based on the global solution, these pieces of the perturbation can be written in terms of a tail integral over the body's past history. This approach can be applied at any order to obtain a self-consistent approximation that is valid on long timescales, both near and far from the small body. I conclude by discussing possible extensions of my method and comparing it to alternative approaches. |
0805.3175 | Isabeau Pr\'emont-Schwarz | Fotini Markopoulou, Isabeau Pr\'emont-Schwarz | Conserved Topological Defects in Non-Embedded Graphs in Quantum Gravity | 42 pages, 34 figures | Class.Quant.Grav.25:205015,2008 | 10.1088/0264-9381/25/20/205015 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We follow up on previous work which found that commonly used graph evolution
moves lead to conserved quantities that can be expressed in terms of the
braiding of the graph in its embedding space. We study non-embedded graphs
under three distinct sets of dynamical rules and find non-trivial conserved
quantities that can be expressed in terms of topological defects in the dual
geometry. For graphs dual to 2-dimensional simplicial complexes we identify all
the conserved quantities of the evolution. We also indicate expected results
for graphs dual to 3-dimensional simplicial complexes.
| [
{
"created": "Tue, 20 May 2008 20:46:32 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Nov 2008 02:12:48 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Markopoulou",
"Fotini",
""
],
[
"Prémont-Schwarz",
"Isabeau",
""
]
] | We follow up on previous work which found that commonly used graph evolution moves lead to conserved quantities that can be expressed in terms of the braiding of the graph in its embedding space. We study non-embedded graphs under three distinct sets of dynamical rules and find non-trivial conserved quantities that can be expressed in terms of topological defects in the dual geometry. For graphs dual to 2-dimensional simplicial complexes we identify all the conserved quantities of the evolution. We also indicate expected results for graphs dual to 3-dimensional simplicial complexes. |
2112.02364 | Xun Xue | Jing Li, Yongxiang Zhou and Xun Xue | Spatial Curvature and Large Scale Lorentz Violation | 17 pages, 16 figures | null | 10.1088/1674-1137/ac5319 | null | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | The tension between the Hubble constant obtained from the local measurements
and from cosmic microwave background (CMB) measurements motivated us to
consider the cosmological model beyond $\Lambda$CDM one. We investigate the
cosmology in the large scale Lorentz violation model with non-vanishing spatial
curvature. The degeneracy among spatial curvature, cosmological constant and
cosmological contortion distribution makes the model viable in describing the
known observation date. We get some constraints on the spatial curvature by the
comparison of the relation between measured distance modulus and red-shift with
the predicted one, the evolution of matter density over time and the evolution
of effective cosmological constant. The performance of large scale Lorentz
violation model with non-vanishing spatial curvature under these constrains is
discussed.
| [
{
"created": "Sat, 4 Dec 2021 15:47:47 GMT",
"version": "v1"
}
] | 2022-06-15 | [
[
"Li",
"Jing",
""
],
[
"Zhou",
"Yongxiang",
""
],
[
"Xue",
"Xun",
""
]
] | The tension between the Hubble constant obtained from the local measurements and from cosmic microwave background (CMB) measurements motivated us to consider the cosmological model beyond $\Lambda$CDM one. We investigate the cosmology in the large scale Lorentz violation model with non-vanishing spatial curvature. The degeneracy among spatial curvature, cosmological constant and cosmological contortion distribution makes the model viable in describing the known observation date. We get some constraints on the spatial curvature by the comparison of the relation between measured distance modulus and red-shift with the predicted one, the evolution of matter density over time and the evolution of effective cosmological constant. The performance of large scale Lorentz violation model with non-vanishing spatial curvature under these constrains is discussed. |
1807.10281 | Alexander Vikman | Eugeny Babichev, Sabir Ramazanov, Alexander Vikman | Recovering P(X) from a canonical complex field | 16 pages+appendices, references added, matches the published version | JCAP11(2018)023 | 10.1088/1475-7516/2018/11/023 | LPT-Orsay-18-89 | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the correspondence between models of a self-interacting canonical
complex scalar field and P(X)-theories/shift-symmetric k-essence. Both describe
the same background cosmological dynamics, provided that the amplitude of the
complex scalar is frozen modulo the Hubble drag. We compare perturbations in
these two theories on top of a fixed cosmological background. The dispersion
relation for the complex scalar has two branches. In the small momentum limit,
one of these branches coincides with the dispersion relation of the
P(X)-theory. Hence, the low momentum phase velocity agrees with the sound speed
in the corresponding P(X)-theory. The behavior of high frequency modes
associated with the second branch of the dispersion relation depends on the
value of the sound speed. In the subluminal case, the second branch has a mass
gap. On the contrary, in the superluminal case, this branch is vulnerable to a
tachyonic instability. We also discuss the special case of the P(X)-theories
with an imaginary sound speed leading to the catastrophic gradient instability.
The complex field models provide with a cutoff on the momenta involved in the
instability.
| [
{
"created": "Thu, 26 Jul 2018 16:53:14 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Aug 2018 13:49:07 GMT",
"version": "v2"
},
{
"created": "Tue, 20 Nov 2018 09:24:33 GMT",
"version": "v3"
}
] | 2018-11-21 | [
[
"Babichev",
"Eugeny",
""
],
[
"Ramazanov",
"Sabir",
""
],
[
"Vikman",
"Alexander",
""
]
] | We study the correspondence between models of a self-interacting canonical complex scalar field and P(X)-theories/shift-symmetric k-essence. Both describe the same background cosmological dynamics, provided that the amplitude of the complex scalar is frozen modulo the Hubble drag. We compare perturbations in these two theories on top of a fixed cosmological background. The dispersion relation for the complex scalar has two branches. In the small momentum limit, one of these branches coincides with the dispersion relation of the P(X)-theory. Hence, the low momentum phase velocity agrees with the sound speed in the corresponding P(X)-theory. The behavior of high frequency modes associated with the second branch of the dispersion relation depends on the value of the sound speed. In the subluminal case, the second branch has a mass gap. On the contrary, in the superluminal case, this branch is vulnerable to a tachyonic instability. We also discuss the special case of the P(X)-theories with an imaginary sound speed leading to the catastrophic gradient instability. The complex field models provide with a cutoff on the momenta involved in the instability. |
1801.02250 | Stephan Reimers | Kevin Eickhoff, Stephan Reimers | Dynamics of test particles in the five-dimensional G\"{o}del spacetime | null | Phys. Rev. D 98, 044050 (2018) | 10.1103/PhysRevD.98.044050 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive the complete set of geodesic equations for massive and massless,
charged test particles of a five-dimensional, rotating and charged solution of
the Einstein-Maxwell-Chern-Simons field equations in five-dimensional minimal
gauged supergravity and present their analytical solutions. We study the polar
and radial motion, depending on the spacetime and test particle parameters, and
characterize the test particle motion qualitatively by the means of parametric
plots and effective potentials. We use the analytical solutions in order to
visualize the test particle motion by three-dimensional plots.
| [
{
"created": "Sun, 7 Jan 2018 20:58:40 GMT",
"version": "v1"
}
] | 2018-09-12 | [
[
"Eickhoff",
"Kevin",
""
],
[
"Reimers",
"Stephan",
""
]
] | We derive the complete set of geodesic equations for massive and massless, charged test particles of a five-dimensional, rotating and charged solution of the Einstein-Maxwell-Chern-Simons field equations in five-dimensional minimal gauged supergravity and present their analytical solutions. We study the polar and radial motion, depending on the spacetime and test particle parameters, and characterize the test particle motion qualitatively by the means of parametric plots and effective potentials. We use the analytical solutions in order to visualize the test particle motion by three-dimensional plots. |
0910.1170 | Marek Lipert | Marek Lipert | Nonlinear stability of the Taub-NUT soliton in 6+1 dimensions | 19 pages, 5 figures | Class.Quant.Grav.27:145002,2010 | 10.1088/0264-9381/27/14/145002 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using mixed numerical and analytical methods we give evidence that the 6+1
dimensional Taub-NUT soliton is asymptotically nonlinearly stable against small
perturbations preserving biaxial Bianchi IX symmetry. We also show that for
sufficiently strong perturbations the soliton collapses to a warped black hole.
Since this black hole solution is not known in closed form, for completeness of
the exposition we prove its existence and determine its properties. In
particular, the mass of the black hole is computed.
| [
{
"created": "Wed, 7 Oct 2009 07:13:13 GMT",
"version": "v1"
},
{
"created": "Tue, 31 Aug 2010 16:06:55 GMT",
"version": "v2"
}
] | 2010-09-01 | [
[
"Lipert",
"Marek",
""
]
] | Using mixed numerical and analytical methods we give evidence that the 6+1 dimensional Taub-NUT soliton is asymptotically nonlinearly stable against small perturbations preserving biaxial Bianchi IX symmetry. We also show that for sufficiently strong perturbations the soliton collapses to a warped black hole. Since this black hole solution is not known in closed form, for completeness of the exposition we prove its existence and determine its properties. In particular, the mass of the black hole is computed. |
1911.05415 | Colin MacLaurin | Colin MacLaurin | Expanding space, redshifts, and rigidity: Conceptual issues in cosmology | 60 pages, 16 figures. Master's thesis at the University of Queensland | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | I examine the interpretation of photon redshifts in curved spacetime, as
being gravitational or Doppler in origin. In
Friedmann-Lema\^itre-Robertson-Walker spacetime, redshifts between comoving
observers are often attributed to "expanding space", whereas in Schwarzschild
spacetime, redshifts between static observers are attributed to "gravitational"
causes. Yet various authors have suggested a freely falling observer congruence
would interpret any redshift as Doppler, whereas a rigid congruence must
interpret it as gravitational since there is no relative motion. I realise this
proposal by explicitly constructing coordinate systems for rigid motion in the
above spacetimes. This includes an extensive analysis of observer-dependent
distance measurement in curved spacetime. I also introduce Rindler
acceleration, the Milne model, and Newtonian cosmology.
| [
{
"created": "Wed, 13 Nov 2019 12:01:54 GMT",
"version": "v1"
}
] | 2019-11-14 | [
[
"MacLaurin",
"Colin",
""
]
] | I examine the interpretation of photon redshifts in curved spacetime, as being gravitational or Doppler in origin. In Friedmann-Lema\^itre-Robertson-Walker spacetime, redshifts between comoving observers are often attributed to "expanding space", whereas in Schwarzschild spacetime, redshifts between static observers are attributed to "gravitational" causes. Yet various authors have suggested a freely falling observer congruence would interpret any redshift as Doppler, whereas a rigid congruence must interpret it as gravitational since there is no relative motion. I realise this proposal by explicitly constructing coordinate systems for rigid motion in the above spacetimes. This includes an extensive analysis of observer-dependent distance measurement in curved spacetime. I also introduce Rindler acceleration, the Milne model, and Newtonian cosmology. |
1502.04399 | Hee-Suk Cho | Hee-Suk Cho | Parameter estimation using a complete signal and inspiral templates for
low mass binary black holes with Advanced LIGO sensitivity | 24 pages, 16 figures, major revision from version 1, matched to the
published version in CQG | Class. Quantum Grav. 32 (2015) 235007 | 10.1088/0264-9381/32/23/235007 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the validity of inspiral templates in gravitational wave data
analysis with Advanced LIGO sensitivity for low mass binary black holes with
total masses of $M \leq 30 Msun$. We mainly focus on the nonspinning system. As
our complete inspiral-merger-ringdown waveform model ($IMR$), we assume the
phenomenological model, "PhenomA", and define our inspiral template model
($Imerg$) by taking the inspiral part into account from $IMR$ up to the merger
frequency (fmerg). We first calculate the {\it true} statistical uncertainties
using $IMR$ signals and $IMR$ templates. Next, using $IMR$ signals and $Imerg$
templates, we calculate fitting factors and systematic biases, and compare the
biases with the {\it true} statistical uncertainties. We find that the valid
criteria of the bank of $Imerg$ templates are obtained as $Mcrit \sim 24 Msun$
for detection (if $M>Mcrit$, the fitting factor is smaller than $0.97$), and
$Mcrit \sim 26 Msun$ for parameter estimation (if $M>Mcrit$, the systematic
bias is larger than the {\it true} statistical uncertainty where the signal to
noise ratio is $20$), respectively. In order to see the dependence on the
cutoff frequency of the inspiral waveforms, we define another inspiral model
$Iisco$ which is terminated at the innermost-stable-circular-orbit frequency
($fisco<fmerg$). We find that the valid criteria of the bank of $Iisco$
templates are obtained as $Mcrit \sim 15 Msun$ and $\sim 17 Msun$ for detection
and parameter estimation, respectively. We investigate the statistical
uncertainties for the inspiral template models considering various signal to
noise ratios, and compare those to the {\it true} statistical uncertainties. We
also consider the aligned-spinning system with fixed mass ratio ($m_1/m_2=3$)
and spin ($\chi=0.5$) by employing the recent phenomenological model,
"PhenomC".
| [
{
"created": "Mon, 16 Feb 2015 01:17:44 GMT",
"version": "v1"
},
{
"created": "Mon, 12 Oct 2015 05:49:34 GMT",
"version": "v2"
}
] | 2015-11-10 | [
[
"Cho",
"Hee-Suk",
""
]
] | We study the validity of inspiral templates in gravitational wave data analysis with Advanced LIGO sensitivity for low mass binary black holes with total masses of $M \leq 30 Msun$. We mainly focus on the nonspinning system. As our complete inspiral-merger-ringdown waveform model ($IMR$), we assume the phenomenological model, "PhenomA", and define our inspiral template model ($Imerg$) by taking the inspiral part into account from $IMR$ up to the merger frequency (fmerg). We first calculate the {\it true} statistical uncertainties using $IMR$ signals and $IMR$ templates. Next, using $IMR$ signals and $Imerg$ templates, we calculate fitting factors and systematic biases, and compare the biases with the {\it true} statistical uncertainties. We find that the valid criteria of the bank of $Imerg$ templates are obtained as $Mcrit \sim 24 Msun$ for detection (if $M>Mcrit$, the fitting factor is smaller than $0.97$), and $Mcrit \sim 26 Msun$ for parameter estimation (if $M>Mcrit$, the systematic bias is larger than the {\it true} statistical uncertainty where the signal to noise ratio is $20$), respectively. In order to see the dependence on the cutoff frequency of the inspiral waveforms, we define another inspiral model $Iisco$ which is terminated at the innermost-stable-circular-orbit frequency ($fisco<fmerg$). We find that the valid criteria of the bank of $Iisco$ templates are obtained as $Mcrit \sim 15 Msun$ and $\sim 17 Msun$ for detection and parameter estimation, respectively. We investigate the statistical uncertainties for the inspiral template models considering various signal to noise ratios, and compare those to the {\it true} statistical uncertainties. We also consider the aligned-spinning system with fixed mass ratio ($m_1/m_2=3$) and spin ($\chi=0.5$) by employing the recent phenomenological model, "PhenomC". |
gr-qc/0411082 | Slava G. Turyshev | Slava G. Turyshev, James G. Williams, Michael Shao, John D. Anderson,
Kenneth L. Nordtvedt Jr, and Thomas W. Murphy Jr | Laser Ranging to the Moon, Mars and Beyond | 37 pages, 9 figures, 1 table. Invited talk given at ``The 2004
NASA/JPL Workshop on Physics for Planetary Exploration.'' April 20-22, 2004,
Solvang, CA | null | null | null | gr-qc | null | Current and future optical technologies will aid exploration of the Moon and
Mars while advancing fundamental physics research in the solar system.
Technologies and possible improvements in the laser-enabled tests of various
physical phenomena are considered along with a space architecture that could be
the cornerstone for robotic and human exploration of the solar system. In
particular, accurate ranging to the Moon and Mars would not only lead to
construction of a new space communication infrastructure enabling an improved
navigational accuracy, but will also provide a significant improvement in
several tests of gravitational theory: the equivalence principle, geodetic
precession, PPN parameters $\beta$ and $\gamma$, and possible variation of the
gravitational constant $G$. Other tests would become possible with an optical
architecture that would allow proceeding from meter to centimeter to millimeter
range accuracies on interplanetary distances. This paper discusses the current
state and the future improvements in the tests of relativistic gravity with
Lunar Laser Ranging (LLR). We also consider precision gravitational tests with
the future laser ranging to Mars and discuss optical design of the proposed
Laser Astrometric Test of Relativity (LATOR) mission. We emphasize that already
existing capabilities can offer significant improvements not only in the tests
of fundamental physics, but may also establish the infrastructure for space
exploration in the near future. Looking to future exploration, what
characteristics are desired for the next generation of ranging devices, what is
the optimal architecture that would benefit both space exploration and
fundamental physics, and what fundamental questions can be investigated? We try
to answer these questions.
| [
{
"created": "Tue, 16 Nov 2004 19:40:50 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Turyshev",
"Slava G.",
""
],
[
"Williams",
"James G.",
""
],
[
"Shao",
"Michael",
""
],
[
"Anderson",
"John D.",
""
],
[
"Nordtvedt",
"Kenneth L.",
"Jr"
],
[
"Murphy",
"Thomas W.",
"Jr"
]
] | Current and future optical technologies will aid exploration of the Moon and Mars while advancing fundamental physics research in the solar system. Technologies and possible improvements in the laser-enabled tests of various physical phenomena are considered along with a space architecture that could be the cornerstone for robotic and human exploration of the solar system. In particular, accurate ranging to the Moon and Mars would not only lead to construction of a new space communication infrastructure enabling an improved navigational accuracy, but will also provide a significant improvement in several tests of gravitational theory: the equivalence principle, geodetic precession, PPN parameters $\beta$ and $\gamma$, and possible variation of the gravitational constant $G$. Other tests would become possible with an optical architecture that would allow proceeding from meter to centimeter to millimeter range accuracies on interplanetary distances. This paper discusses the current state and the future improvements in the tests of relativistic gravity with Lunar Laser Ranging (LLR). We also consider precision gravitational tests with the future laser ranging to Mars and discuss optical design of the proposed Laser Astrometric Test of Relativity (LATOR) mission. We emphasize that already existing capabilities can offer significant improvements not only in the tests of fundamental physics, but may also establish the infrastructure for space exploration in the near future. Looking to future exploration, what characteristics are desired for the next generation of ranging devices, what is the optimal architecture that would benefit both space exploration and fundamental physics, and what fundamental questions can be investigated? We try to answer these questions. |
2112.10813 | Subenoy Chakraborty | Akash Bose, Subenoy Chakraborty | Is warm inflation quasi-stable? | 11 Pages | Phys.Dark Univ. 35 (2022) 100938 | 10.1016/j.dark.2021.100938 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The present work deals with a non-equilibrium thermodynamics that is
associated with the scenario of warm inflation. The premise is that an
adiabatic radiation production process holds exactly i.e. the radiation
dilution is exactly counterbalanced by a dissipation term. Under this
hypothesis, it is found that radiation particle number, temperature, radiation
energy density and pressure are all conserved -- a contradiction to the very
nature of the warm inflation dynamics. However, such exact adiabatic radiation
production process never happens in any realistic analysis of warm inflation.
In the slow roll approximation this holds at best at the zeroth order. Finally
it is shown that a variable cosmological constant may accommodate the
quasi-stable process in warm inflation with non-equilibrium thermodynamic
description.
| [
{
"created": "Fri, 17 Dec 2021 05:25:19 GMT",
"version": "v1"
}
] | 2021-12-22 | [
[
"Bose",
"Akash",
""
],
[
"Chakraborty",
"Subenoy",
""
]
] | The present work deals with a non-equilibrium thermodynamics that is associated with the scenario of warm inflation. The premise is that an adiabatic radiation production process holds exactly i.e. the radiation dilution is exactly counterbalanced by a dissipation term. Under this hypothesis, it is found that radiation particle number, temperature, radiation energy density and pressure are all conserved -- a contradiction to the very nature of the warm inflation dynamics. However, such exact adiabatic radiation production process never happens in any realistic analysis of warm inflation. In the slow roll approximation this holds at best at the zeroth order. Finally it is shown that a variable cosmological constant may accommodate the quasi-stable process in warm inflation with non-equilibrium thermodynamic description. |
1603.07267 | Burkhard Kleihaus | Burkhard Kleihaus and Jutta Kunz | Black Holes in Higher Dimensions (Black Strings and Black Rings) | Report on the session Black Holes in Higher Dimensions of the MG14
meeting; references added | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The last three years have again seen new exciting developments in the area of
higher dimensional black objects. For black objects with noncompact higher
dimensions, the solution space was exlored further within the blackfold
approach and with numerical schemes, yielding a large variety of new families
of solutions, while limiting procedures created so-called super-entropic black
holes. Concerning compact extra dimensions, the sequences of static nonuniform
black strings in five and six dimensions were extended to impressively large
values of the nonuniformity parameter with extreme numerical precision, showing
that an oscillating pattern arises for the mass, the area or the temperature,
while approaching the conjectured double-cone merger solution. Besides the
presentation of interesting new types of higherdimensional solutions, also
their physical properties were addressed in this session. While the main focus
was on Einstein gravity, a significant number of talks also covered Lovelock
theories.
| [
{
"created": "Wed, 23 Mar 2016 16:56:01 GMT",
"version": "v1"
},
{
"created": "Fri, 1 Apr 2016 11:31:38 GMT",
"version": "v2"
}
] | 2016-04-04 | [
[
"Kleihaus",
"Burkhard",
""
],
[
"Kunz",
"Jutta",
""
]
] | The last three years have again seen new exciting developments in the area of higher dimensional black objects. For black objects with noncompact higher dimensions, the solution space was exlored further within the blackfold approach and with numerical schemes, yielding a large variety of new families of solutions, while limiting procedures created so-called super-entropic black holes. Concerning compact extra dimensions, the sequences of static nonuniform black strings in five and six dimensions were extended to impressively large values of the nonuniformity parameter with extreme numerical precision, showing that an oscillating pattern arises for the mass, the area or the temperature, while approaching the conjectured double-cone merger solution. Besides the presentation of interesting new types of higherdimensional solutions, also their physical properties were addressed in this session. While the main focus was on Einstein gravity, a significant number of talks also covered Lovelock theories. |
2307.12824 | Bogeun Gwak | Kihong Kwon, Juli\'an Barrag\'an Amado, Bogeun Gwak | Absorption cross section in gravity's rainbow from confluent Heun
equation | 19 pages | Class.Quant.Grav. 41 (2024) 035005 | 10.1088/1361-6382/ad1b92 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the scattering of a massless scalar field by a charged
non-rotating black hole in the presence of gravity's rainbow. Using the
connection coefficients of the confluent Heun equation expressed in terms of
the semi-classical confluent conformal blocks and the instanton part of the
Nekrasov-Shatashvili (NS) free energy, we obtain an asymptotic expansion for
the low-energy absorption cross section.
| [
{
"created": "Mon, 24 Jul 2023 14:22:25 GMT",
"version": "v1"
}
] | 2024-01-19 | [
[
"Kwon",
"Kihong",
""
],
[
"Amado",
"Julián Barragán",
""
],
[
"Gwak",
"Bogeun",
""
]
] | We investigate the scattering of a massless scalar field by a charged non-rotating black hole in the presence of gravity's rainbow. Using the connection coefficients of the confluent Heun equation expressed in terms of the semi-classical confluent conformal blocks and the instanton part of the Nekrasov-Shatashvili (NS) free energy, we obtain an asymptotic expansion for the low-energy absorption cross section. |
0808.1602 | Sachie Shiomi | Sachie Shiomi | Proposal for a geophysical search for dilatonic waves | null | Phys.Rev.D78:042001,2008 | 10.1103/PhysRevD.78.042001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose a new method of searching for the composition-dependent dilatonic
waves, predicted by unified theories of strings. In this method, Earth's
surface-gravity changes due to translational motions of its inner core, excited
by dilatonic waves, are searched for by using superconducting gravimeters. This
method has its best sensitivity at the frequency of $\sim$ 7 $\times$ 10$^{-5}$
Hz, which is lower than the sensitive frequencies of previous proposals using
gravitational-wave detectors: $\sim$ 10 to 1000 Hz. Using available results of
surface-gravity measurements with superconducting gravimeters and assuming a
simple Earth model, we present preliminary upper limits on the energy density
of a stochastic background of massless dilatons at the low frequency. Though
the results are currently limited by the uncertainty in the Earth model, this
method has a potential of detecting dilatonic waves in a new window.
| [
{
"created": "Tue, 12 Aug 2008 02:03:45 GMT",
"version": "v1"
}
] | 2010-04-15 | [
[
"Shiomi",
"Sachie",
""
]
] | We propose a new method of searching for the composition-dependent dilatonic waves, predicted by unified theories of strings. In this method, Earth's surface-gravity changes due to translational motions of its inner core, excited by dilatonic waves, are searched for by using superconducting gravimeters. This method has its best sensitivity at the frequency of $\sim$ 7 $\times$ 10$^{-5}$ Hz, which is lower than the sensitive frequencies of previous proposals using gravitational-wave detectors: $\sim$ 10 to 1000 Hz. Using available results of surface-gravity measurements with superconducting gravimeters and assuming a simple Earth model, we present preliminary upper limits on the energy density of a stochastic background of massless dilatons at the low frequency. Though the results are currently limited by the uncertainty in the Earth model, this method has a potential of detecting dilatonic waves in a new window. |
1606.04481 | Celio Muniz | M. S. Cunha, C. R. Muniz, H. R. Christiansen, and V. B. Bezerra | Relativistic Landau Levels in the Rotating Cosmic String Spacetime | Writing and grammar revised. References added. 14 pages, no figures.
To appear in European Phys. J. C | null | 10.1140/epjc/s10052-016-4357-5 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the spacetime induced by a rotating cosmic string we compute the energy
levels of a massive spinless particle coupled covariantly to a homogeneous
magnetic field parallel to the string. Afterwards, we consider the addition of
a scalar potential with a Coulomb-type and a linear confining term and
completely solve the Klein-Gordon equations for each configuration. Finally,
assuming rigid-wall boundary conditions, we find the Landau levels when the
linear defect is itself magnetized. Remarkably, our analysis reveals that the
Landau quantization occurs even in the absence of gauge fields provided the
string is endowed with spin.
| [
{
"created": "Tue, 14 Jun 2016 18:05:45 GMT",
"version": "v1"
},
{
"created": "Wed, 15 Jun 2016 14:56:41 GMT",
"version": "v2"
},
{
"created": "Wed, 7 Sep 2016 16:55:54 GMT",
"version": "v3"
}
] | 2016-10-12 | [
[
"Cunha",
"M. S.",
""
],
[
"Muniz",
"C. R.",
""
],
[
"Christiansen",
"H. R.",
""
],
[
"Bezerra",
"V. B.",
""
]
] | In the spacetime induced by a rotating cosmic string we compute the energy levels of a massive spinless particle coupled covariantly to a homogeneous magnetic field parallel to the string. Afterwards, we consider the addition of a scalar potential with a Coulomb-type and a linear confining term and completely solve the Klein-Gordon equations for each configuration. Finally, assuming rigid-wall boundary conditions, we find the Landau levels when the linear defect is itself magnetized. Remarkably, our analysis reveals that the Landau quantization occurs even in the absence of gauge fields provided the string is endowed with spin. |
2111.00212 | Mohammad Atazadeh | K. Atazadeh | Maximum force conjecture in Kiselev, $4$D-EGB and Barrow
corrected-entropy black holes | 7 pages, 2 figures | Phys. Lett. B 820 (2021) 136590 | 10.1016/j.physletb.2021.136590 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The classical maximum force bound in the general relativity (GR) is defined
between two black holes with touching horizons. We consider the maximum force
conjecture for Kiselev solution that the black holes surrounded by
quintessential matter, $w=-2/3$. We show that the maximum force bound is
independent of black hole masses in this solution and we also indicate that
when two black holes surrounded by static quintessence, the maximum force
between them can approach to zero. In continue, we also study the maximum force
bound for $4$D Einstein-Gauss-Bonnet ($4$D-EGB) black holes and we obtain that
in this theory the maximum force bound exists and the force is bigger than the
maximum force in GR. Finally, we consider the Barrow entropy in the framework
of the entropic force theories and find that the maximum force only holds when
the exponent of the corrected-entropy, namely $\Delta$, goes to zero and for
other ranges of $\Delta$ it does not hold in which the mass dependence in the
maximum force bound may cause the formation of naked singularities.
| [
{
"created": "Sat, 30 Oct 2021 09:18:58 GMT",
"version": "v1"
}
] | 2021-11-02 | [
[
"Atazadeh",
"K.",
""
]
] | The classical maximum force bound in the general relativity (GR) is defined between two black holes with touching horizons. We consider the maximum force conjecture for Kiselev solution that the black holes surrounded by quintessential matter, $w=-2/3$. We show that the maximum force bound is independent of black hole masses in this solution and we also indicate that when two black holes surrounded by static quintessence, the maximum force between them can approach to zero. In continue, we also study the maximum force bound for $4$D Einstein-Gauss-Bonnet ($4$D-EGB) black holes and we obtain that in this theory the maximum force bound exists and the force is bigger than the maximum force in GR. Finally, we consider the Barrow entropy in the framework of the entropic force theories and find that the maximum force only holds when the exponent of the corrected-entropy, namely $\Delta$, goes to zero and for other ranges of $\Delta$ it does not hold in which the mass dependence in the maximum force bound may cause the formation of naked singularities. |
gr-qc/0005115 | Samuli Hemming | Samuli Hemming and Esko Keski-Vakkuri | Hawking Radiation from AdS Black Holes | 13 pages, latex2e, v2: some clarifications and references added | Phys.Rev.D64:044006,2001 | 10.1103/PhysRevD.64.044006 | HIP-2000-25/TH | gr-qc | null | We investigate Hawking radiation from black holes in (d+1)-dimensional
anti-de Sitter space. We focus on s-waves, make use of the geometrical optics
approximation, and follow three approaches to analyze the radiation. First, we
compute a Bogoliubov transformation between Kruskal and asymptotic coordinates
and compare the different vacua. Second, following a method due to Kraus,
Parikh, and Wilczek, we view Hawking radiation as a tunneling process across
the horizon and compute the tunneling probablility. This approach uses an
anti-de Sitter version of a metric originally introduced by Painleve for
Schwarzschild black holes. From the tunneling probability one also finds a
leading correction to the semi-classical emission rate arising from the
backreaction to the background geometry. Finally, we consider a spherically
symmetric collapse geometry and the Bogoliubov transformation between the
initial vacuum state and the vacuum of an asymptotic observer.
| [
{
"created": "Thu, 25 May 2000 08:41:55 GMT",
"version": "v1"
},
{
"created": "Mon, 3 Jul 2000 14:08:13 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Hemming",
"Samuli",
""
],
[
"Keski-Vakkuri",
"Esko",
""
]
] | We investigate Hawking radiation from black holes in (d+1)-dimensional anti-de Sitter space. We focus on s-waves, make use of the geometrical optics approximation, and follow three approaches to analyze the radiation. First, we compute a Bogoliubov transformation between Kruskal and asymptotic coordinates and compare the different vacua. Second, following a method due to Kraus, Parikh, and Wilczek, we view Hawking radiation as a tunneling process across the horizon and compute the tunneling probablility. This approach uses an anti-de Sitter version of a metric originally introduced by Painleve for Schwarzschild black holes. From the tunneling probability one also finds a leading correction to the semi-classical emission rate arising from the backreaction to the background geometry. Finally, we consider a spherically symmetric collapse geometry and the Bogoliubov transformation between the initial vacuum state and the vacuum of an asymptotic observer. |
gr-qc/9405075 | Gil Lewis | Gilbert N. Lewis (Michigan Technological University, Houghton,
Michigan and Richard N. Lewis) | The Behavior of a Spherical Hole in an Infinite Uniform Universe | 32 pages, LaTex, 3 postscript figures, MTU-MA-94-001 | null | null | null | gr-qc | null | In this paper, the behavior of a spherical hole in an otherwise infinite and
uniform universe is investigated. First, the Newtonian theory is developed. The
concept of negative gravity, an outward gravitational force acting away from
the center of the spherical hole, is presented, and the resulting expansion of
the hole is investigated. Then, the same result is derived using the techniques
of Einstein's theory of general relativity. The field equations are solved for
an infinite uniform universe and then for an infinite universe in which matter
is uniformly distributed except for a spherical hole. Negative pressure caused
by negative gravity is utilized. The physical significance of the cosmological
constant is explained, and a new physical concept, that of the gravitational
potential of a hole, is discussed. The relationship between the Newtonian
potential for a hole and the Schwarzschild solution of the field equations is
explored. Finally, the geodesic equations are considered. It is shown that
photons and particles are deflected away from the hole. An application of this
idea is pursued, in which a new cosmology based upon expanding holes in a
uniform universe is developed. The microwave background radiation and Hubble's
Law, among others, are explained. Finally, current astronomical data are used
to compute a remarkably accurate value of Hubble's constant, as well as
estimates of the average mass density of the universe and the cosmological
constant.
| [
{
"created": "Tue, 31 May 1994 19:33:00 GMT",
"version": "v1"
}
] | 2009-09-25 | [
[
"Lewis",
"Gilbert N.",
"",
"Michigan Technological University, Houghton,\n Michigan and Richard N. Lewis"
]
] | In this paper, the behavior of a spherical hole in an otherwise infinite and uniform universe is investigated. First, the Newtonian theory is developed. The concept of negative gravity, an outward gravitational force acting away from the center of the spherical hole, is presented, and the resulting expansion of the hole is investigated. Then, the same result is derived using the techniques of Einstein's theory of general relativity. The field equations are solved for an infinite uniform universe and then for an infinite universe in which matter is uniformly distributed except for a spherical hole. Negative pressure caused by negative gravity is utilized. The physical significance of the cosmological constant is explained, and a new physical concept, that of the gravitational potential of a hole, is discussed. The relationship between the Newtonian potential for a hole and the Schwarzschild solution of the field equations is explored. Finally, the geodesic equations are considered. It is shown that photons and particles are deflected away from the hole. An application of this idea is pursued, in which a new cosmology based upon expanding holes in a uniform universe is developed. The microwave background radiation and Hubble's Law, among others, are explained. Finally, current astronomical data are used to compute a remarkably accurate value of Hubble's constant, as well as estimates of the average mass density of the universe and the cosmological constant. |
1208.2228 | Hal Haggard | Eugenio Bianchi and Hal M. Haggard | Bohr-Sommerfeld Quantization of Space | 32 pages, 10 figures | Phys.Rev. D86 (2012) 124010 | 10.1103/PhysRevD.86.124010 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We introduce semiclassical methods into the study of the volume spectrum in
loop gravity. The classical system behind a 4-valent spinnetwork node is a
Euclidean tetrahedron. We investigate the tetrahedral volume dynamics on phase
space and apply Bohr-Sommerfeld quantization to find the volume spectrum. The
analysis shows a remarkable quantitative agreement with the volume spectrum
computed in loop gravity. Moreover, it provides new geometrical insights into
the degeneracy of this spectrum and the maximum and minimum eigenvalues of the
volume on intertwiner space.
| [
{
"created": "Fri, 10 Aug 2012 17:40:46 GMT",
"version": "v1"
}
] | 2014-02-19 | [
[
"Bianchi",
"Eugenio",
""
],
[
"Haggard",
"Hal M.",
""
]
] | We introduce semiclassical methods into the study of the volume spectrum in loop gravity. The classical system behind a 4-valent spinnetwork node is a Euclidean tetrahedron. We investigate the tetrahedral volume dynamics on phase space and apply Bohr-Sommerfeld quantization to find the volume spectrum. The analysis shows a remarkable quantitative agreement with the volume spectrum computed in loop gravity. Moreover, it provides new geometrical insights into the degeneracy of this spectrum and the maximum and minimum eigenvalues of the volume on intertwiner space. |
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