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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1503.09080 | Otakar Svitek | T. Tahamtan, O. Svitek | Robinson-Trautman solution with scalar hair | to appear in PRD | Phys. Rev. D 91: 104032, 2015 | 10.1103/PhysRevD.91.104032 | null | gr-qc | http://creativecommons.org/licenses/by/3.0/ | Explicit Robinson-Trautman solution with minimally coupled free scalar field
is derived and analyzed. It is shown that this solution contains curvature
singularity which is initially naked but later the horizon envelopes it. We use
quasilocal horizon definition and prove its existence in later retarded times
using sub- and supersolution method combined with growth estimates. We show
that the solution is generally of algebraic type II but reduces to type D in
spherical symmetry.
| [
{
"created": "Tue, 31 Mar 2015 15:13:53 GMT",
"version": "v1"
},
{
"created": "Thu, 7 May 2015 08:35:12 GMT",
"version": "v2"
}
] | 2015-07-31 | [
[
"Tahamtan",
"T.",
""
],
[
"Svitek",
"O.",
""
]
] | Explicit Robinson-Trautman solution with minimally coupled free scalar field is derived and analyzed. It is shown that this solution contains curvature singularity which is initially naked but later the horizon envelopes it. We use quasilocal horizon definition and prove its existence in later retarded times using sub- and supersolution method combined with growth estimates. We show that the solution is generally of algebraic type II but reduces to type D in spherical symmetry. |
2404.07659 | Jonathan Luk | C\'ecile Huneau and Jonathan Luk | High-frequency solutions to the Einstein equations | 34 pages, review article | null | null | null | gr-qc math.AP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We review recent mathematical results concerning the high-frequency solutions
to the Einstein vacuum equations and the limits of these solutions. In
particular, we focus on two conjectures of Burnett, which attempt to give an
exact characterization of high-frequency limits of vacuum spacetimes as
solutions to the Einstein-massless Vlasov system. Some open problems and future
directions are discussed.
| [
{
"created": "Thu, 11 Apr 2024 11:47:24 GMT",
"version": "v1"
}
] | 2024-04-12 | [
[
"Huneau",
"Cécile",
""
],
[
"Luk",
"Jonathan",
""
]
] | We review recent mathematical results concerning the high-frequency solutions to the Einstein vacuum equations and the limits of these solutions. In particular, we focus on two conjectures of Burnett, which attempt to give an exact characterization of high-frequency limits of vacuum spacetimes as solutions to the Einstein-massless Vlasov system. Some open problems and future directions are discussed. |
2009.06407 | Michael Hobson | Michael Hobson, Anthony Lasenby | Weyl gauge theories of gravity do not predict a second clock effect | 11 pages, no figures, submitted to PRD. arXiv admin note: text
overlap with arXiv:1510.06699 | Phys. Rev. D 102, 084040 (2020) | 10.1103/PhysRevD.102.084040 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider Weyl gauge theories of gravity (WGTs), which are invariant both
under local Poincar\'e transformations and local changes of scale. Such
theories may be interpreted as gauge theories in Minkowski spacetime, but their
gravitational interactions are most often reinterpreted geometrically in terms
of a Weyl--Cartan spacetime, in which any matter fields then reside. Such a
spacetime is a straightforward generalisation of Weyl spacetime to include
torsion. As first suggested by Einstein, Weyl spacetime is believed to exhibit
a so-called second clock effect, which prevents the existence of experimentally
observed sharp spectral lines, since the rates of (atomic) clocks depend on
their past history. The prevailing view in the literature is that this rules
out WGTs as unphysical. Contrary to this viewpoint, we show that if one adopts
the natural covariant derivative identified in the geometric interpretation of
WGTs, properly takes into account the scaling dimension of physical quantities,
and recognises that Einstein's original objection requires the presence of
massive matter fields to represent atoms, observers and clocks, then WGTs do
not predict a second clock effect.
| [
{
"created": "Fri, 11 Sep 2020 16:56:22 GMT",
"version": "v1"
}
] | 2021-03-25 | [
[
"Hobson",
"Michael",
""
],
[
"Lasenby",
"Anthony",
""
]
] | We consider Weyl gauge theories of gravity (WGTs), which are invariant both under local Poincar\'e transformations and local changes of scale. Such theories may be interpreted as gauge theories in Minkowski spacetime, but their gravitational interactions are most often reinterpreted geometrically in terms of a Weyl--Cartan spacetime, in which any matter fields then reside. Such a spacetime is a straightforward generalisation of Weyl spacetime to include torsion. As first suggested by Einstein, Weyl spacetime is believed to exhibit a so-called second clock effect, which prevents the existence of experimentally observed sharp spectral lines, since the rates of (atomic) clocks depend on their past history. The prevailing view in the literature is that this rules out WGTs as unphysical. Contrary to this viewpoint, we show that if one adopts the natural covariant derivative identified in the geometric interpretation of WGTs, properly takes into account the scaling dimension of physical quantities, and recognises that Einstein's original objection requires the presence of massive matter fields to represent atoms, observers and clocks, then WGTs do not predict a second clock effect. |
2007.08118 | Guansheng He | Guansheng He and Wenbin Lin | Gravitational frequency shift of light in equatorial plane of a radially
moving Schwarzschild black hole | null | Mon. Not. R. Astron. Soc. 470, 3877 (2017) | 10.1093/mnras/stx1539 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The kinematical effect induced by the transversal motion of a gravitational
lens on the frequency shift of light has been investigated in detail, while the
effect of the radial motion is thought to be much smaller than the transversal
one and thus has usually been neglected. In this work, we find that the radial
velocity effect on the frequency shift has the same order of magnitude as that
of the transversal velocity effect, when the light emitter (or the receiver) is
close to the gravitational lens with the distance between them being an impact
parameter scale. The significant velocity effect is usually transient due to
the motion of the gravitational lens relative to the light emitter or the
receiver.
| [
{
"created": "Thu, 16 Jul 2020 05:10:02 GMT",
"version": "v1"
}
] | 2020-07-17 | [
[
"He",
"Guansheng",
""
],
[
"Lin",
"Wenbin",
""
]
] | The kinematical effect induced by the transversal motion of a gravitational lens on the frequency shift of light has been investigated in detail, while the effect of the radial motion is thought to be much smaller than the transversal one and thus has usually been neglected. In this work, we find that the radial velocity effect on the frequency shift has the same order of magnitude as that of the transversal velocity effect, when the light emitter (or the receiver) is close to the gravitational lens with the distance between them being an impact parameter scale. The significant velocity effect is usually transient due to the motion of the gravitational lens relative to the light emitter or the receiver. |
gr-qc/0106063 | Roberto Colistete Junior | N. Pinto-Neto, R. Colistete Jr | Graceful exit from inflation using quantum cosmology | 8 pages, RevTeX, 4 Postscript figures, uses graficx.sty. Added more
text and references | Phys.Lett.A290:219-226,2001 | 10.1016/S0375-9601(01)00674-0 | null | gr-qc | null | A massless scalar field without self interaction and string coupled to
gravity is quantized in the framework of quantum cosmology using the Bohm-de
Broglie interpretation. Gaussian superpositions of the quantum solutions of the
corresponding Wheeler-DeWitt equation in minisuperspace are constructed. The
bohmian trajectories obtained exhibit a graceful exit from the inflationary
Pre-Big Bang epoch to the decelerated expansion phase.
| [
{
"created": "Wed, 20 Jun 2001 21:33:59 GMT",
"version": "v1"
},
{
"created": "Fri, 7 Dec 2001 21:12:51 GMT",
"version": "v2"
}
] | 2009-09-25 | [
[
"Pinto-Neto",
"N.",
""
],
[
"Colistete",
"R.",
"Jr"
]
] | A massless scalar field without self interaction and string coupled to gravity is quantized in the framework of quantum cosmology using the Bohm-de Broglie interpretation. Gaussian superpositions of the quantum solutions of the corresponding Wheeler-DeWitt equation in minisuperspace are constructed. The bohmian trajectories obtained exhibit a graceful exit from the inflationary Pre-Big Bang epoch to the decelerated expansion phase. |
gr-qc/9508017 | Eric Poisson | Eric Poisson | Gravitational waves from coalescing compact binaries | LaTeX, 18 pages, two figures coming separately in .uu format (just
follow the instructions at the beginning of the file). To appear in the
Proceedings of the Sixth Canadian Conference on General Relativity and
Relativistic Astrophysics | null | null | null | gr-qc | null | This article is intended to provide a pedagogical account of issues related
to, and recent work on, gravitational waves from coalescing compact binaries
(composed of neutron stars and/or black holes). These waves are the most
promising for kilometer-size interferometric detectors such as LIGO and VIRGO.
Topics discussed include: interferometric detectors and their noise; coalescing
compact binaries and their gravitational waveforms; the technique of matched
filtering for signal detection and measurement; waveform calculations in
post-Newtonian theory and in the black-hole perturbation approach; and the
accuracy of the post-Newtonian expansion.
| [
{
"created": "Mon, 7 Aug 1995 22:38:14 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Poisson",
"Eric",
""
]
] | This article is intended to provide a pedagogical account of issues related to, and recent work on, gravitational waves from coalescing compact binaries (composed of neutron stars and/or black holes). These waves are the most promising for kilometer-size interferometric detectors such as LIGO and VIRGO. Topics discussed include: interferometric detectors and their noise; coalescing compact binaries and their gravitational waveforms; the technique of matched filtering for signal detection and measurement; waveform calculations in post-Newtonian theory and in the black-hole perturbation approach; and the accuracy of the post-Newtonian expansion. |
gr-qc/0201055 | Ezra T. Newman | Ezra T. Newman | On a Classical, Geometric Origin of Magnetic Moments, Spin-Angular
Momentum and the Dirac Gyromagnetic Ratio | 17 pages | Phys.Rev. D65 (2002) 104005 | 10.1103/PhysRevD.65.104005 | null | gr-qc | null | By treating the real Maxwell Field and real linearized Einstein equations as
being imbedded in complex Minkowski space, one can interpret magnetic moments
and spin-angular momentum as arising from a charge and mass monopole source
moving along a complex world line in the complex Minkowski space. In the
circumstances where the complex center of mass world-line coincides with the
complex center of charge world-line, the gyromagnetic ratio is that of the
Dirac electron.
| [
{
"created": "Wed, 16 Jan 2002 20:42:13 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Newman",
"Ezra T.",
""
]
] | By treating the real Maxwell Field and real linearized Einstein equations as being imbedded in complex Minkowski space, one can interpret magnetic moments and spin-angular momentum as arising from a charge and mass monopole source moving along a complex world line in the complex Minkowski space. In the circumstances where the complex center of mass world-line coincides with the complex center of charge world-line, the gyromagnetic ratio is that of the Dirac electron. |
0710.3540 | Etera R. Livine | Etera R. Livine, James P. Ryan | N=2 supersymmetric spin foams in three dimensions | 12 pages | Class.Quant.Grav.25:175014,2008 | 10.1088/0264-9381/25/17/175014 | null | gr-qc hep-th | null | We construct the spin foam model for N=2 supergravity in three dimensions.
Classically, it is a BF theory with gauge algebra osp(2|2). This algebra has
representations which are not completely reducible. This complicates the
procedure when building a state sum. Fortunately, one can and should excise
these representations. We show that the restricted subset of representations
form a subcategory closed under tensor product. The resulting state-sum is once
again a topological invariant. Furthermore, within this framework one can
identify positively and negatively charged fermions propagating on the spin
foam. These results on osp(2|2) representations and intertwiners apply more
generally to spin network states for N=2 loop quantum supergravity (in 3+1
dimensions) where it allows to define a notion of BPS states.
| [
{
"created": "Thu, 18 Oct 2007 15:40:45 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Livine",
"Etera R.",
""
],
[
"Ryan",
"James P.",
""
]
] | We construct the spin foam model for N=2 supergravity in three dimensions. Classically, it is a BF theory with gauge algebra osp(2|2). This algebra has representations which are not completely reducible. This complicates the procedure when building a state sum. Fortunately, one can and should excise these representations. We show that the restricted subset of representations form a subcategory closed under tensor product. The resulting state-sum is once again a topological invariant. Furthermore, within this framework one can identify positively and negatively charged fermions propagating on the spin foam. These results on osp(2|2) representations and intertwiners apply more generally to spin network states for N=2 loop quantum supergravity (in 3+1 dimensions) where it allows to define a notion of BPS states. |
1201.2562 | Boris E. Meierovich | Boris E. Meierovich | To the theory of the Universe evolution | 25 pages, 9figures | Physical Review D 85, 123544 (2012) | 10.1103/PhysRevD.85.123544 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Self-consistent account of the most simple non-gauge vector fields leads to a
broad spectrum of regular scenarios of temporal evolution of the Universe
completely within the frames of the Einstein's General relativity. The
longitudinal non-gauge vector field is "the missing link in the chain",
displaying the repulsive elasticity and allowing the macroscopic description of
the main features of the Universe evolution. The singular Big Bang turns into a
regular inflation-like state of maximum compression with the further
accelerated expansion at late times. The parametric freedom of the theory
allows to forget the troubles of fine tuning. In the most interesting cases the
analytical solutions of the Einstein's equations are found.
| [
{
"created": "Thu, 12 Jan 2012 13:43:32 GMT",
"version": "v1"
}
] | 2015-06-03 | [
[
"Meierovich",
"Boris E.",
""
]
] | Self-consistent account of the most simple non-gauge vector fields leads to a broad spectrum of regular scenarios of temporal evolution of the Universe completely within the frames of the Einstein's General relativity. The longitudinal non-gauge vector field is "the missing link in the chain", displaying the repulsive elasticity and allowing the macroscopic description of the main features of the Universe evolution. The singular Big Bang turns into a regular inflation-like state of maximum compression with the further accelerated expansion at late times. The parametric freedom of the theory allows to forget the troubles of fine tuning. In the most interesting cases the analytical solutions of the Einstein's equations are found. |
1907.05233 | Kazuharu Bamba | Z. Yousaf, Kazuharu Bamba, M. Z. Bhatti and U. Ghafoor | Charged Gravastars in Modified Gravity | 23 pages, 6 figures, final version to appear in Physical Review D | Phys. Rev. D 100, 024062 (2019) | 10.1103/PhysRevD.100.024062 | FU-PCG-63 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we investigate the effects of electromagnetic field on the
isotropic spherical gravastar models in metric $f(R,T)$ gravity. For this
purpose, we have explored singularity-free exact models of relativistic spheres
with a specific equation of state. After considering Reissner Nordstr\"{o}m
spacetime as an exterior region, the interior charged manifold is matched at
the junction interface. Several viable realistic characteristics of the
spherical gravastar model are studied in the presence of electromagnetic field
through graphical representations. It is concluded that the electric charge has
a substantial role in the modeling of proper length, energy contents, entropy
and equation of state parameter of the stellar system. We have also explored
the stable regions of the charged gravastar structures.
| [
{
"created": "Tue, 9 Jul 2019 14:01:58 GMT",
"version": "v1"
},
{
"created": "Fri, 26 Jul 2019 17:21:29 GMT",
"version": "v2"
}
] | 2020-03-03 | [
[
"Yousaf",
"Z.",
""
],
[
"Bamba",
"Kazuharu",
""
],
[
"Bhatti",
"M. Z.",
""
],
[
"Ghafoor",
"U.",
""
]
] | In this paper, we investigate the effects of electromagnetic field on the isotropic spherical gravastar models in metric $f(R,T)$ gravity. For this purpose, we have explored singularity-free exact models of relativistic spheres with a specific equation of state. After considering Reissner Nordstr\"{o}m spacetime as an exterior region, the interior charged manifold is matched at the junction interface. Several viable realistic characteristics of the spherical gravastar model are studied in the presence of electromagnetic field through graphical representations. It is concluded that the electric charge has a substantial role in the modeling of proper length, energy contents, entropy and equation of state parameter of the stellar system. We have also explored the stable regions of the charged gravastar structures. |
1607.06636 | Tim Dietrich | Tim Dietrich, Maximiliano Ujevic, Wolfgang Tichy, Sebastiano Bernuzzi,
Bernd Bruegmann | Gravitational waves and mass ejecta from binary neutron star mergers:
Effect of the mass-ratio | null | Phys. Rev. D 95, 024029 (2017) | 10.1103/PhysRevD.95.024029 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present new (3+1)D numerical relativity simulations of the binary neutron
star (BNS) merger and postmerger phase. We focus on a previously inaccessible
region of the binary parameter space spanning the binary's mass-ratio
$q\sim1.00-1.75$ for different total masses and equations of state, and up to
$q\sim2$ for a stiff BNS system. We study the mass-ratio effect on the
gravitational waves (GWs) and on the possible electromagnetic emission
associated to dynamical mass ejecta. We compute waveforms, spectra, and
spectrograms of the GW strain including all the multipoles up to $l=4$. The
mass-ratio has a specific imprint on the GW multipoles in the
late-inspiral-merger signal, and it affects qualitatively the spectra of the
merger remnant. The multipole effect is also studied by considering the
dependency of the GW spectrograms on the source's sky location. Unequal mass
BNSs produce more ejecta than equal mass systems with ejecta masses and kinetic
energies depending almost linearly on $q$. We estimate luminosity peaks and
light curves of macronovae events associated to the mergers using a simple
approach. For $q\sim2$ the luminosity peak is delayed for several days and can
be up to four times larger than for the $q=1$ cases. The macronova emission
associated with the $q\sim2$ BNS is more persistent in time and could be
observed for weeks instead of few days ($q=1$) in the near infrared. Finally,
we estimate the flux of possible radio flares produced by the interaction of
relativistic outflows with the surrounding medium. Also in this case a large
$q$ can significantly enhance the emission and delay the peak luminosity.
Overall, our results indicate that BNS merger with large mass ratio have EM
signatures distinct from the equal mass case and more similar to black hole -
neutron star binaries.
| [
{
"created": "Fri, 22 Jul 2016 11:26:39 GMT",
"version": "v1"
}
] | 2017-02-01 | [
[
"Dietrich",
"Tim",
""
],
[
"Ujevic",
"Maximiliano",
""
],
[
"Tichy",
"Wolfgang",
""
],
[
"Bernuzzi",
"Sebastiano",
""
],
[
"Bruegmann",
"Bernd",
""
]
] | We present new (3+1)D numerical relativity simulations of the binary neutron star (BNS) merger and postmerger phase. We focus on a previously inaccessible region of the binary parameter space spanning the binary's mass-ratio $q\sim1.00-1.75$ for different total masses and equations of state, and up to $q\sim2$ for a stiff BNS system. We study the mass-ratio effect on the gravitational waves (GWs) and on the possible electromagnetic emission associated to dynamical mass ejecta. We compute waveforms, spectra, and spectrograms of the GW strain including all the multipoles up to $l=4$. The mass-ratio has a specific imprint on the GW multipoles in the late-inspiral-merger signal, and it affects qualitatively the spectra of the merger remnant. The multipole effect is also studied by considering the dependency of the GW spectrograms on the source's sky location. Unequal mass BNSs produce more ejecta than equal mass systems with ejecta masses and kinetic energies depending almost linearly on $q$. We estimate luminosity peaks and light curves of macronovae events associated to the mergers using a simple approach. For $q\sim2$ the luminosity peak is delayed for several days and can be up to four times larger than for the $q=1$ cases. The macronova emission associated with the $q\sim2$ BNS is more persistent in time and could be observed for weeks instead of few days ($q=1$) in the near infrared. Finally, we estimate the flux of possible radio flares produced by the interaction of relativistic outflows with the surrounding medium. Also in this case a large $q$ can significantly enhance the emission and delay the peak luminosity. Overall, our results indicate that BNS merger with large mass ratio have EM signatures distinct from the equal mass case and more similar to black hole - neutron star binaries. |
1812.09135 | Raihaneh Moti | R. Moti and A. Shojai | On the cutoff identification and the quantum improvement in
asymptotically safe gravity | null | null | 10.1016/j.physletb.2019.04.062 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Applying the exact renormalization group method to search the nonGaussian
fixed points of gravitational coupling, is frequently followed by two steps:
cutoff identification and improvement. Although there are various models for
identifying the cutoff momentum by some physical length, saving the general
covariance should be considered as an important property in the procedure. In
this paper, use of an arbitrary function of curvature invariants for cutoff
identification is suggested. It is shown that the field equations for this
approach differs from the ones obtained from the conventional cutoff
identification and improvement, even for nonvacuum solutions of the improved
Einstein equations. Indeed, it is concluded that these two steps are correlated
to each other.
| [
{
"created": "Fri, 21 Dec 2018 14:16:34 GMT",
"version": "v1"
},
{
"created": "Fri, 26 Apr 2019 09:36:24 GMT",
"version": "v2"
},
{
"created": "Thu, 9 May 2019 17:50:08 GMT",
"version": "v3"
}
] | 2019-05-10 | [
[
"Moti",
"R.",
""
],
[
"Shojai",
"A.",
""
]
] | Applying the exact renormalization group method to search the nonGaussian fixed points of gravitational coupling, is frequently followed by two steps: cutoff identification and improvement. Although there are various models for identifying the cutoff momentum by some physical length, saving the general covariance should be considered as an important property in the procedure. In this paper, use of an arbitrary function of curvature invariants for cutoff identification is suggested. It is shown that the field equations for this approach differs from the ones obtained from the conventional cutoff identification and improvement, even for nonvacuum solutions of the improved Einstein equations. Indeed, it is concluded that these two steps are correlated to each other. |
gr-qc/9912043 | Luis Herrera | L. Herrera, A. Di Prisco and D. Pavon | Measuring the strength of dissipative inflation | 8 pages, Latex. To appear in Gen.Rel.Grav | Gen.Rel.Grav. 32 (2000) 2091-2097 | 10.1023/A:1001990217528 | null | gr-qc astro-ph | null | We comment on recently proposed dissipative inflationary models. It is shown
that the strength of the inflationary expansion is related to a specific
combination of thermodynamic variables which is known to measure the
instability of self-gravitating dissipative systems.
| [
{
"created": "Fri, 10 Dec 1999 16:41:00 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Herrera",
"L.",
""
],
[
"Di Prisco",
"A.",
""
],
[
"Pavon",
"D.",
""
]
] | We comment on recently proposed dissipative inflationary models. It is shown that the strength of the inflationary expansion is related to a specific combination of thermodynamic variables which is known to measure the instability of self-gravitating dissipative systems. |
gr-qc/0010109 | Jerry B. Griffiths | J. Podolsky and J. B. Griffiths | Uniformly accelerating black holes in a de Sitter universe | 6 pages REVTeX, 3 figures, to appear in Phys. Rev. D. Figure 2
corrected | Phys.Rev. D63 (2001) 024006 | 10.1103/PhysRevD.63.024006 | null | gr-qc | null | A class of exact solutions of Einstein's equations is analysed which
describes uniformly accelerating charged black holes in an asymptotically de
Sitter universe. This is a generalisation of the C-metric which includes a
cosmological constant. The physical interpretation of the solutions is
facilitated by the introduction of a new coordinate system for de Sitter space
which is adapted to accelerating observers in this background. The solutions
considered reduce to this form of the de Sitter metric when the mass and charge
of the black holes vanish.
| [
{
"created": "Mon, 30 Oct 2000 17:01:03 GMT",
"version": "v1"
},
{
"created": "Tue, 31 Oct 2000 13:02:22 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Podolsky",
"J.",
""
],
[
"Griffiths",
"J. B.",
""
]
] | A class of exact solutions of Einstein's equations is analysed which describes uniformly accelerating charged black holes in an asymptotically de Sitter universe. This is a generalisation of the C-metric which includes a cosmological constant. The physical interpretation of the solutions is facilitated by the introduction of a new coordinate system for de Sitter space which is adapted to accelerating observers in this background. The solutions considered reduce to this form of the de Sitter metric when the mass and charge of the black holes vanish. |
0908.4234 | Plamen Fiziev | Plamen P. Fiziev | Classes of Exact Solutions to the Teukolsky Master Equation | 27 pages, LaTeX file, no figures. Final version | Class. Quant. Grav.27:135001, 2010 | 10.1088/0264-9381/27/13/135001 | SU-TH-01-08-2009 | gr-qc astro-ph.HE hep-th math-ph math.MP | http://creativecommons.org/licenses/publicdomain/ | The Teukolsky Master Equation is the basic tool for study of perturbations of
the Kerr metric in linear approximation. It admits separation of variables,
thus yielding the Teukolsky Radial Equation and the Teukolsky Angular Equation.
We present here a unified description of all classes of exact solutions to
these equations in terms of the confluent Heun functions. Large classes of new
exact solutions are found and classified with respect to their characteristic
properties. Special attention is paid to the polynomial solutions which are
singular ones and introduce collimated one-way-running waves. It is shown that
a proper linear combination of such solutions can present bounded
one-way-running waves. This type of waves may be suitable as models of the
observed astrophysical jets.
| [
{
"created": "Fri, 28 Aug 2009 16:16:47 GMT",
"version": "v1"
},
{
"created": "Wed, 2 Sep 2009 11:06:56 GMT",
"version": "v2"
},
{
"created": "Tue, 27 Oct 2009 19:31:55 GMT",
"version": "v3"
},
{
"created": "Wed, 12 May 2010 05:38:32 GMT",
"version": "v4"
}
] | 2010-05-25 | [
[
"Fiziev",
"Plamen P.",
""
]
] | The Teukolsky Master Equation is the basic tool for study of perturbations of the Kerr metric in linear approximation. It admits separation of variables, thus yielding the Teukolsky Radial Equation and the Teukolsky Angular Equation. We present here a unified description of all classes of exact solutions to these equations in terms of the confluent Heun functions. Large classes of new exact solutions are found and classified with respect to their characteristic properties. Special attention is paid to the polynomial solutions which are singular ones and introduce collimated one-way-running waves. It is shown that a proper linear combination of such solutions can present bounded one-way-running waves. This type of waves may be suitable as models of the observed astrophysical jets. |
gr-qc/0010044 | B. S. Sathyaprakash | B.S. Sathyaprakash | Mother templates for gravitational wave chirps | 7 pages, CQG style file (iopart.cls) | Class.Quant.Grav.17:L157-162,2000 | 10.1088/0264-9381/17/23/101 | null | gr-qc | null | Templates used in a search for binary black holes and neutron stars in
gravitational wave interferometer data will have to be computed on-line since
the computational storage and retrieval costs for the template bank are too
expensive. The conventional dimensionless variable $T=(c^3/Gm)t,$ where $m$ is
the total mass of a binary, in the time-domain and a not-so-conventional
velocity-like variable $v=(\pi Gm f)^{1/3}$ in the Fourier-domain, render the
phasing of the waves independent of the total mass of the system enabling the
construction of {\it mother templates} that depend only on the mass ratio of a
black hole binary. Use of such mother templates in a template bank will bring
about a reduction in computational costs up to a factor of 10 and a saving on
storage by a factor of 100.
| [
{
"created": "Wed, 11 Oct 2000 21:42:29 GMT",
"version": "v1"
}
] | 2010-04-06 | [
[
"Sathyaprakash",
"B. S.",
""
]
] | Templates used in a search for binary black holes and neutron stars in gravitational wave interferometer data will have to be computed on-line since the computational storage and retrieval costs for the template bank are too expensive. The conventional dimensionless variable $T=(c^3/Gm)t,$ where $m$ is the total mass of a binary, in the time-domain and a not-so-conventional velocity-like variable $v=(\pi Gm f)^{1/3}$ in the Fourier-domain, render the phasing of the waves independent of the total mass of the system enabling the construction of {\it mother templates} that depend only on the mass ratio of a black hole binary. Use of such mother templates in a template bank will bring about a reduction in computational costs up to a factor of 10 and a saving on storage by a factor of 100. |
1301.2788 | Behnam Pourhassan | Behnam Pourhassan | Viscous Modified Cosmic Chaplygin Gas Cosmology | null | International Journal of Modern Physics D Vol. 22, No. 9 (2013)
1350061 | 10.1142/S0218271813500612 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we construct modified cosmic Chaplygin gas which has viscosity.
We use exponential function method to solve non-linear equation and obtain
time-dependent dark energy density. Then discuss Hubble expansion parameter and
scale factor and fix them by using observational data. We also investigate
stability of this theory.
| [
{
"created": "Sun, 13 Jan 2013 16:26:17 GMT",
"version": "v1"
}
] | 2013-06-05 | [
[
"Pourhassan",
"Behnam",
""
]
] | In this paper we construct modified cosmic Chaplygin gas which has viscosity. We use exponential function method to solve non-linear equation and obtain time-dependent dark energy density. Then discuss Hubble expansion parameter and scale factor and fix them by using observational data. We also investigate stability of this theory. |
2202.11327 | Hwajin Eom | Hwajin Eom, Wontae Kim | Analytic approach to the formation of a three-dimensional black string
from a dust cloud | 18 pages, 1 figure, comments and references added | JCAP 11 (2022) 004 | 10.1088/1475-7516/2022/11/004 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In three-dimensional low-energy string theory, we study the formation of a
black string from a dust cloud. We analytically obtain two distinct classes of
exact solutions with arbitrary functions responsible for mass distributions of
the dust cloud. The first and second kinds of solutions may describe collapsing
dusts but the first kind is only for inhomogeneous dust distribution while the
second kind has a homogeneous limit. The finite collapse time and the Israel
junction conditions tell us that the first kind solution describes a desired
collapsing phenomenon, whereas the scale factor in the inner spacetime for the
second kind turns out to be trivial. In the first kind solution, specific
collapsing models can be realized by choosing an appropriate inhomogeneous dust
distribution consistent with the Israel junction conditions. Consequently, the
inhomogeneous dust cloud eventually collapses to the black string although the
homogeneous dust cloud does not guarantee the formation of the black string in
our setting. The space-like curvature singularities occur at the finite
collapse time and they can be cloaked by the horizon of the black string.
| [
{
"created": "Wed, 23 Feb 2022 06:51:55 GMT",
"version": "v1"
},
{
"created": "Mon, 7 Nov 2022 02:32:11 GMT",
"version": "v2"
}
] | 2022-11-08 | [
[
"Eom",
"Hwajin",
""
],
[
"Kim",
"Wontae",
""
]
] | In three-dimensional low-energy string theory, we study the formation of a black string from a dust cloud. We analytically obtain two distinct classes of exact solutions with arbitrary functions responsible for mass distributions of the dust cloud. The first and second kinds of solutions may describe collapsing dusts but the first kind is only for inhomogeneous dust distribution while the second kind has a homogeneous limit. The finite collapse time and the Israel junction conditions tell us that the first kind solution describes a desired collapsing phenomenon, whereas the scale factor in the inner spacetime for the second kind turns out to be trivial. In the first kind solution, specific collapsing models can be realized by choosing an appropriate inhomogeneous dust distribution consistent with the Israel junction conditions. Consequently, the inhomogeneous dust cloud eventually collapses to the black string although the homogeneous dust cloud does not guarantee the formation of the black string in our setting. The space-like curvature singularities occur at the finite collapse time and they can be cloaked by the horizon of the black string. |
1811.11137 | Daniel Blixt | Daniel Blixt, Manuel Hohmann, Christian Pfeifer | Hamiltonian and primary constraints of new general relativity | 13 pages, 1 figure, journal version | Phys. Rev. D 99, 084025 (2019) | 10.1103/PhysRevD.99.084025 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive the kinematic Hamiltonian for the so-called "new general
relativity" class of teleparallel gravity theories, which is the most general
class of theories whose Lagrangian is quadratic in the torsion tensor and does
not contain parity violating terms. Our approach makes use of an explicit
expression for the flat, in general, nonvanishing spin connection, which avoids
the use of Lagrange multipliers, while keeping the theory invariant under local
Lorentz transformations. We clarify the relation between the dynamics of the
spin connection degrees of freedom and the tetrads. The terms constituting the
Hamiltonian of the theory can be decomposed into irreducible parts under the
rotation group. Using this, we demonstrate that there are nine different
classes of theories, which are distinguished by the occurrence or
non-occurrence of certain primary constraints. We visualize these different
classes and show that the decomposition into irreducible parts allows us to
write the Hamiltonian in a common form for all nine classes, which reproduces
the specific Hamiltonians of more restricted classes in which particular
primary constraints appear.
| [
{
"created": "Tue, 27 Nov 2018 17:54:44 GMT",
"version": "v1"
},
{
"created": "Fri, 3 May 2019 11:10:26 GMT",
"version": "v2"
}
] | 2019-05-06 | [
[
"Blixt",
"Daniel",
""
],
[
"Hohmann",
"Manuel",
""
],
[
"Pfeifer",
"Christian",
""
]
] | We derive the kinematic Hamiltonian for the so-called "new general relativity" class of teleparallel gravity theories, which is the most general class of theories whose Lagrangian is quadratic in the torsion tensor and does not contain parity violating terms. Our approach makes use of an explicit expression for the flat, in general, nonvanishing spin connection, which avoids the use of Lagrange multipliers, while keeping the theory invariant under local Lorentz transformations. We clarify the relation between the dynamics of the spin connection degrees of freedom and the tetrads. The terms constituting the Hamiltonian of the theory can be decomposed into irreducible parts under the rotation group. Using this, we demonstrate that there are nine different classes of theories, which are distinguished by the occurrence or non-occurrence of certain primary constraints. We visualize these different classes and show that the decomposition into irreducible parts allows us to write the Hamiltonian in a common form for all nine classes, which reproduces the specific Hamiltonians of more restricted classes in which particular primary constraints appear. |
2011.01865 | Gabriele Franciolini | Kaze W. K. Wong, Gabriele Franciolini, Valerio De Luca, Vishal
Baibhav, Emanuele Berti, Paolo Pani and Antonio Riotto | Constraining the primordial black hole scenario with Bayesian inference
and machine learning: the GWTC-2 gravitational wave catalog | 14 pages, 5 figures. v2: matching published version | Phys. Rev. D 103, 023026 (2021) | 10.1103/PhysRevD.103.023026 | null | gr-qc astro-ph.CO hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Primordial black holes (PBHs) might be formed in the early Universe and could
comprise at least a fraction of the dark matter. Using the recently released
GWTC-2 dataset from the third observing run of the LIGO-Virgo Collaboration, we
investigate whether current observations are compatible with the hypothesis
that all black hole mergers detected so far are of primordial origin. We
constrain PBH formation models within a hierarchical Bayesian inference
framework based on deep learning techniques, finding best-fit values for
distinctive features of these models, including the PBH initial mass function,
the fraction of PBHs in dark matter, and the accretion efficiency. The presence
of several spinning binaries in the GWTC-2 dataset favors a scenario in which
PBHs accrete and spin up. Our results indicate that PBHs may comprise only a
fraction smaller than $0.3 \%$ of the total dark matter, and that the predicted
PBH abundance is still compatible with other constraints.
| [
{
"created": "Tue, 3 Nov 2020 17:37:56 GMT",
"version": "v1"
},
{
"created": "Mon, 11 Jan 2021 14:23:41 GMT",
"version": "v2"
}
] | 2021-02-03 | [
[
"Wong",
"Kaze W. K.",
""
],
[
"Franciolini",
"Gabriele",
""
],
[
"De Luca",
"Valerio",
""
],
[
"Baibhav",
"Vishal",
""
],
[
"Berti",
"Emanuele",
""
],
[
"Pani",
"Paolo",
""
],
[
"Riotto",
"Antonio",
""
]
... | Primordial black holes (PBHs) might be formed in the early Universe and could comprise at least a fraction of the dark matter. Using the recently released GWTC-2 dataset from the third observing run of the LIGO-Virgo Collaboration, we investigate whether current observations are compatible with the hypothesis that all black hole mergers detected so far are of primordial origin. We constrain PBH formation models within a hierarchical Bayesian inference framework based on deep learning techniques, finding best-fit values for distinctive features of these models, including the PBH initial mass function, the fraction of PBHs in dark matter, and the accretion efficiency. The presence of several spinning binaries in the GWTC-2 dataset favors a scenario in which PBHs accrete and spin up. Our results indicate that PBHs may comprise only a fraction smaller than $0.3 \%$ of the total dark matter, and that the predicted PBH abundance is still compatible with other constraints. |
1903.03974 | Igor Fomin | Igor V. Fomin and Sergey V. Chervon | Reconstruction of GR cosmological solutions in modified gravity theories | 4 figures | Phys. Rev. D 100, 023511 (2019) | 10.1103/PhysRevD.100.023511 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the special class of the exact solutions in cosmological models
based on the Generalized Scalar-Tensor Gravity with non-minimal coupling of a
scalar field to the Ricci scalar and to the Gauss-Bonnet scalar in 4D Friedmann
universe corresponding to similar ones in GR. The parameters of cosmological
perturbations in such models correspond to the case of Einstein gravity with a
high precision. As the example of proposed approach, we obtain the exact
solutions for the power-law and exponential power-law inflation.
| [
{
"created": "Sun, 10 Mar 2019 11:52:06 GMT",
"version": "v1"
}
] | 2019-07-17 | [
[
"Fomin",
"Igor V.",
""
],
[
"Chervon",
"Sergey V.",
""
]
] | We study the special class of the exact solutions in cosmological models based on the Generalized Scalar-Tensor Gravity with non-minimal coupling of a scalar field to the Ricci scalar and to the Gauss-Bonnet scalar in 4D Friedmann universe corresponding to similar ones in GR. The parameters of cosmological perturbations in such models correspond to the case of Einstein gravity with a high precision. As the example of proposed approach, we obtain the exact solutions for the power-law and exponential power-law inflation. |
2306.08856 | N S Kavya | N. S. Kavya, G. Mustafa, V. Venkatesha, P.K. Sahoo | Exploring wormhole solutions in curvature-matter coupling gravity
supported by noncommutative geometry and conformal symmetry | Accepted version in Chinese Journal of Physics | null | 10.1016/j.cjph.2024.01.004 | null | gr-qc | http://creativecommons.org/licenses/by-nc-nd/4.0/ | This article explores new physically viable wormhole solutions within the
framework of f(R,Lm) gravity theory, incorporating noncommutative backgrounds
and conformal symmetries. The study investigates the impact of model parameters
on the existence and properties of wormholes. The derived shape function is
found to obey all the required criteria. Specific attention is given to
traceless wormholes with Gaussian and Lorentzian distributions, investigating
the behavior of the shape functions and energy conditions. In both cases, the
presence of exotic fluid is confirmed.
| [
{
"created": "Thu, 15 Jun 2023 04:51:57 GMT",
"version": "v1"
},
{
"created": "Sun, 7 Jan 2024 16:06:42 GMT",
"version": "v2"
}
] | 2024-01-09 | [
[
"Kavya",
"N. S.",
""
],
[
"Mustafa",
"G.",
""
],
[
"Venkatesha",
"V.",
""
],
[
"Sahoo",
"P. K.",
""
]
] | This article explores new physically viable wormhole solutions within the framework of f(R,Lm) gravity theory, incorporating noncommutative backgrounds and conformal symmetries. The study investigates the impact of model parameters on the existence and properties of wormholes. The derived shape function is found to obey all the required criteria. Specific attention is given to traceless wormholes with Gaussian and Lorentzian distributions, investigating the behavior of the shape functions and energy conditions. In both cases, the presence of exotic fluid is confirmed. |
gr-qc/0205125 | Giovanni Amelino-Camelia | Giovanni Amelino-Camelia | On the fate of Lorentz symmetry in loop quantum gravity and
noncommutative spacetimes | 59 pages, LaTex | null | null | null | gr-qc | null | I analyze the deformation of Lorentz symmetry that holds in certain
noncommutative spacetimes and the way in which Lorentz symmetry is broken in
other noncommutative spacetimes. I also observe that discretization of areas
does not necessarily require departures from Lorentz symmetry. This is due to
the fact that Lorentz symmetry has no implications for exclusive measurement of
the area of a surface, but it governs the combined measurements of the area and
the velocity of a surface. In a quantum-gravity theory Lorentz symmetry can be
consistent with area discretization, but only when the observables ``area of
the surface" and "velocity of the surface" enjoy certain special properties. I
argue that the status of Lorentz symmetry in the loop-quantum-gravity approach
requires careful scrutiny, since areas are discretized within a formalism that,
at least presently, does not include an observable "velocity of the surface".
In general it may prove to be very difficult to reconcile Lorentz symmetry with
area discretization in theories of canonical quantization of gravity, because a
proper description of Lorentz symmetry appears to require that the
fundamental/primary role be played by the surface's world-sheet, whose
"projection" along the space directions of a given observer describes the
observable area, whereas the canonical formalism only allows the introduction
as primary entities of observables defined at a fixed (common) time, and the
observers that can be considered must share that time variable.
| [
{
"created": "Wed, 29 May 2002 19:45:26 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Amelino-Camelia",
"Giovanni",
""
]
] | I analyze the deformation of Lorentz symmetry that holds in certain noncommutative spacetimes and the way in which Lorentz symmetry is broken in other noncommutative spacetimes. I also observe that discretization of areas does not necessarily require departures from Lorentz symmetry. This is due to the fact that Lorentz symmetry has no implications for exclusive measurement of the area of a surface, but it governs the combined measurements of the area and the velocity of a surface. In a quantum-gravity theory Lorentz symmetry can be consistent with area discretization, but only when the observables ``area of the surface" and "velocity of the surface" enjoy certain special properties. I argue that the status of Lorentz symmetry in the loop-quantum-gravity approach requires careful scrutiny, since areas are discretized within a formalism that, at least presently, does not include an observable "velocity of the surface". In general it may prove to be very difficult to reconcile Lorentz symmetry with area discretization in theories of canonical quantization of gravity, because a proper description of Lorentz symmetry appears to require that the fundamental/primary role be played by the surface's world-sheet, whose "projection" along the space directions of a given observer describes the observable area, whereas the canonical formalism only allows the introduction as primary entities of observables defined at a fixed (common) time, and the observers that can be considered must share that time variable. |
1612.04669 | Piyali Bhar | Piyali Bhar, Farook Rahaman, Tuhina Manna and Ayan Banerjee | Wormhole supported by dark energy admitting conformal motion | 9 pages, 2 tables and 4 figures, Accepted for Publication in European
Physical Journal C | null | 10.1140/epjc/s10052-016-4547-1 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this article, we study the possibility of sustaining a static and
spherically symmetric traversable wormhole geometries admitting conformal
motion in Einstein gravity, which presents a more systematic approach to search
a relation between matter and geometry. In wormhole physics, the presence of
exotic matter is a fundamental ingredient and we show that this exotic source
can be dark energy type which support the existence of wormhole spacetimes. In
this work we model a wormhole supported by dark energy which admits conformal
motion. We also discuss the possibility of detection of wormholes in the outer
regions of galactic halos by means of gravitational lensing. The studies of the
total gravitational energy for the exotic matter inside a static wormhole
configuration are also done.
| [
{
"created": "Tue, 13 Dec 2016 06:03:26 GMT",
"version": "v1"
}
] | 2017-02-01 | [
[
"Bhar",
"Piyali",
""
],
[
"Rahaman",
"Farook",
""
],
[
"Manna",
"Tuhina",
""
],
[
"Banerjee",
"Ayan",
""
]
] | In this article, we study the possibility of sustaining a static and spherically symmetric traversable wormhole geometries admitting conformal motion in Einstein gravity, which presents a more systematic approach to search a relation between matter and geometry. In wormhole physics, the presence of exotic matter is a fundamental ingredient and we show that this exotic source can be dark energy type which support the existence of wormhole spacetimes. In this work we model a wormhole supported by dark energy which admits conformal motion. We also discuss the possibility of detection of wormholes in the outer regions of galactic halos by means of gravitational lensing. The studies of the total gravitational energy for the exotic matter inside a static wormhole configuration are also done. |
0906.1120 | Keiko Kokeyama | K. Kokeyama (1), S. Sato (2), A. Nishizawa (3), S. Kawamura (4), Y.
Chen (5) and A. Sugamoto (1) ((1) Ochanomizu University, (2) Hosei
University, (3) Kyoto University, (4) National Astronomical Observatory of
Japan, (5) California Institute of Technology) | Development of displacement- and frequency-noise-free interferometer in
3-D configuration for gravitational wave detection | null | Phys.Rev.Lett.103:171101,2009 | 10.1103/PhysRevLett.103.171101 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The displacement- and frequency-noise-free interferometer (DFI) is a multiple
laser interferometer array for gravitational wave detection free from both the
displacement noise of optics and laser frequency noise. So far, partial
experimental demonstrations of DFI have been done in 2-D table top experiments.
In this paper, we report the complete demonstration of a 3-D DFI. The DFI
consists of four Mach-Zehnder interferometers with four mirrors and two
beamsplitters. The displacement noises both of mirrors and beamsplitters were
suppressed by up to 40 dB. The non-vanishing DFI response to a gravitational
wave was successfully confirmed using multiple electro-optic modulators and
computing methods.
| [
{
"created": "Fri, 5 Jun 2009 13:18:10 GMT",
"version": "v1"
}
] | 2009-10-29 | [
[
"Kokeyama",
"K.",
""
],
[
"Sato",
"S.",
""
],
[
"Nishizawa",
"A.",
""
],
[
"Kawamura",
"S.",
""
],
[
"Chen",
"Y.",
""
],
[
"Sugamoto",
"A.",
""
]
] | The displacement- and frequency-noise-free interferometer (DFI) is a multiple laser interferometer array for gravitational wave detection free from both the displacement noise of optics and laser frequency noise. So far, partial experimental demonstrations of DFI have been done in 2-D table top experiments. In this paper, we report the complete demonstration of a 3-D DFI. The DFI consists of four Mach-Zehnder interferometers with four mirrors and two beamsplitters. The displacement noises both of mirrors and beamsplitters were suppressed by up to 40 dB. The non-vanishing DFI response to a gravitational wave was successfully confirmed using multiple electro-optic modulators and computing methods. |
2307.01264 | Luca Reali | Luca Reali, Andrea Maselli, Emanuele Berti | The impact of compact binary confusion noise on tests of fundamental
physics with next-generation gravitational-wave detectors | 11 pages, 5 figures | null | null | ET-0228A-23 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Next-generation ground-based gravitational-wave observatories such as the
Einstein Telescope and Cosmic Explorer will detect $O(10^{5}-10^{6})$ signals
from compact binary coalescences every year, the exact number depending on
uncertainties in the binary merger rate. Several overlapping signals will be
present in band at any given time, generating a confusion noise background. We
study how this confusion noise affects constraints on possible deviations from
general relativity induced by modified gravity and environmental effects.
Confusion noise impacts only the signals that last longer in band. Even for a
"golden" GW170817-like signal, the constraints broaden by a factor in the range
$[10\%,40\%]$ $([70\%,110\%])$ for the fiducial (highest) value of the local
binary neutron star merger rate. Our ability to test general relativity or
constrain environmental effects will be limited by systematic errors, and not
by confusion noise.
| [
{
"created": "Mon, 3 Jul 2023 18:00:06 GMT",
"version": "v1"
}
] | 2023-07-06 | [
[
"Reali",
"Luca",
""
],
[
"Maselli",
"Andrea",
""
],
[
"Berti",
"Emanuele",
""
]
] | Next-generation ground-based gravitational-wave observatories such as the Einstein Telescope and Cosmic Explorer will detect $O(10^{5}-10^{6})$ signals from compact binary coalescences every year, the exact number depending on uncertainties in the binary merger rate. Several overlapping signals will be present in band at any given time, generating a confusion noise background. We study how this confusion noise affects constraints on possible deviations from general relativity induced by modified gravity and environmental effects. Confusion noise impacts only the signals that last longer in band. Even for a "golden" GW170817-like signal, the constraints broaden by a factor in the range $[10\%,40\%]$ $([70\%,110\%])$ for the fiducial (highest) value of the local binary neutron star merger rate. Our ability to test general relativity or constrain environmental effects will be limited by systematic errors, and not by confusion noise. |
gr-qc/9603046 | Yuri Levin | F.Ya. Khalili (Moscow State University), Yu. Levin (Caltech) | Speed Meter As a Quantum Nondemolition Measuring Device for Force | 7 pages of RevTex, 1 postscript figure | Phys.Rev. D54 (1996) 4735-4737 | 10.1103/PhysRevD.54.4735 | null | gr-qc quant-ph | null | Quantum noise is an important issue for advanced LIGO. Although it is in
principle possible to beat the Standard Quantum Limit (SQL), no practical
recipe has been found yet. This paper dicusses quantum noise in the context of
speedmeter-a devise monitoring the speed of the testmass. The scheme proposed
to overcome SQL in this case might be more practical than the methods based on
monitoring position of the testmass.
| [
{
"created": "Tue, 26 Mar 1996 01:16:03 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Khalili",
"F. Ya.",
"",
"Moscow State University"
],
[
"Levin",
"Yu.",
"",
"Caltech"
]
] | Quantum noise is an important issue for advanced LIGO. Although it is in principle possible to beat the Standard Quantum Limit (SQL), no practical recipe has been found yet. This paper dicusses quantum noise in the context of speedmeter-a devise monitoring the speed of the testmass. The scheme proposed to overcome SQL in this case might be more practical than the methods based on monitoring position of the testmass. |
1207.5502 | Ernesto F. Eiroa | Ernesto F. Eiroa, Carlos M. Sendra | Gravitational lensing by massless braneworld black holes | 12 pages, 4 figures; v3: typos corrected; 1 reference updated | Phys.Rev.D86:083009,2012 | 10.1103/PhysRevD.86.083009 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we study massless braneworld black holes as gravitational
lenses. We find the weak and the strong deflection limits for the deflection
angle, from which we calculate the positions and magnifications of the images.
We compare the results obtained here with those corresponding to Schwarzschild
and Reissner-Nordstrom spacetimes, and also with those found in previous works
for some other braneworld black holes.
| [
{
"created": "Mon, 23 Jul 2012 19:58:14 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Sep 2012 19:12:44 GMT",
"version": "v2"
},
{
"created": "Wed, 24 Oct 2012 17:55:08 GMT",
"version": "v3"
}
] | 2012-10-25 | [
[
"Eiroa",
"Ernesto F.",
""
],
[
"Sendra",
"Carlos M.",
""
]
] | In this paper, we study massless braneworld black holes as gravitational lenses. We find the weak and the strong deflection limits for the deflection angle, from which we calculate the positions and magnifications of the images. We compare the results obtained here with those corresponding to Schwarzschild and Reissner-Nordstrom spacetimes, and also with those found in previous works for some other braneworld black holes. |
1904.12365 | Peng Wang | Peng Wang, Houwen Wu, Haitang Yang | Thermodynamics and Weak Cosmic Censorship Conjecture in Nonlinear
Electrodynamics Black Holes via Charged Particle Absorption | 27 pages, typos corrected, references added | null | null | CTP-SCU/2019006 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We first obtain the $D$-dimensional asymptotically AdS charged black hole
solution in general nonlinear electrodynamics (NLED). We then use the
Hamilton-Jacobi method to describe the motion in curved spacetime of a scalar
particle and a fermion, which, as we show, satisfy the same Hamilton-Jacobi
equation. With absorbing a charged particle, the variation of the generic
charged NLED black hole is calculated in the normal and extended phase spaces.
In the normal phase space, where the cosmological constant and dimensionful
parameters in NLED are fixed, the first and second laws of thermodynamics are
satisfied. In the extended phase space, where the cosmological constant and
dimensionful parameters in NLED are treated as thermodynamic variables, the
first law of thermodynamics is also satisfied. However, the black hole entropy
can either increase or decrease depending on the changes in the dimensionful
parameters. Furthermore, we find that the weak cosmic censorship conjecture is
valid for the extremal and near-extremal black holes in the both phase spaces.
| [
{
"created": "Sun, 28 Apr 2019 18:45:04 GMT",
"version": "v1"
},
{
"created": "Wed, 8 May 2019 06:16:47 GMT",
"version": "v2"
}
] | 2019-05-09 | [
[
"Wang",
"Peng",
""
],
[
"Wu",
"Houwen",
""
],
[
"Yang",
"Haitang",
""
]
] | We first obtain the $D$-dimensional asymptotically AdS charged black hole solution in general nonlinear electrodynamics (NLED). We then use the Hamilton-Jacobi method to describe the motion in curved spacetime of a scalar particle and a fermion, which, as we show, satisfy the same Hamilton-Jacobi equation. With absorbing a charged particle, the variation of the generic charged NLED black hole is calculated in the normal and extended phase spaces. In the normal phase space, where the cosmological constant and dimensionful parameters in NLED are fixed, the first and second laws of thermodynamics are satisfied. In the extended phase space, where the cosmological constant and dimensionful parameters in NLED are treated as thermodynamic variables, the first law of thermodynamics is also satisfied. However, the black hole entropy can either increase or decrease depending on the changes in the dimensionful parameters. Furthermore, we find that the weak cosmic censorship conjecture is valid for the extremal and near-extremal black holes in the both phase spaces. |
2312.10678 | Farruh Atamurotov | Husanboy Hoshimov, Odil Yunusov, Farruh Atamurotov, Mubasher Jamil,
Ahmadjon Abdujabbarov | Weak gravitational lensing and shadow of a GUP-modified Schwarzschild
black hole in the presence of plasma | 22 pages, 13 figures, 2 tables. To appear in Physics of the Dark
Universe | Physics of the Dark Universe, 43 (2024) 101392 | 10.1016/j.dark.2023.101392 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we have studied weak gravitational lensing effect around black
hole and determine shadow radius in GUP-corrected-Schwarzschild spacetime
(S-GUP) in presence of plasma environment. We started with orbits of photons
around black hole in S-GUP. In addition, we have studied shadow and
gravitational weak lensing around such black hole. By using observational data
of EHT project for the M87* and Sgr A*, we have got constrains parameter
$\epsilon$ in S-GUP gravity. Further to make a connection with observations, we
investigate magnification and position of images formed as a result of lensing,
and finally weak deflection angle and magnification for sources near M87* and
Sgr A*.
| [
{
"created": "Sun, 17 Dec 2023 10:45:34 GMT",
"version": "v1"
}
] | 2023-12-29 | [
[
"Hoshimov",
"Husanboy",
""
],
[
"Yunusov",
"Odil",
""
],
[
"Atamurotov",
"Farruh",
""
],
[
"Jamil",
"Mubasher",
""
],
[
"Abdujabbarov",
"Ahmadjon",
""
]
] | In this work, we have studied weak gravitational lensing effect around black hole and determine shadow radius in GUP-corrected-Schwarzschild spacetime (S-GUP) in presence of plasma environment. We started with orbits of photons around black hole in S-GUP. In addition, we have studied shadow and gravitational weak lensing around such black hole. By using observational data of EHT project for the M87* and Sgr A*, we have got constrains parameter $\epsilon$ in S-GUP gravity. Further to make a connection with observations, we investigate magnification and position of images formed as a result of lensing, and finally weak deflection angle and magnification for sources near M87* and Sgr A*. |
1511.01360 | Hyerim Noh | Jai-chan Hwang, Hyerim Noh, Chan-Gyung Park | Fully nonlinear cosmological perturbations of multi-component fluid and
field systems | 18 pages | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present fully nonlinear and exact cosmological perturbation equations in
the presence of multiple components of fluids and minimally coupled scalar
fields. We ignore the tensor-type perturbation. The equations are presented
without taking the temporal gauge condition in the Friedmann background with
general curvature and the cosmological constant. For each fluid component we
ignore the anisotropic stress. The multiple component nature, however,
introduces the anisotropic stress in the collective fluid quantities. We prove
the Newtonian limit of multiple fluids in the zero-shear gauge and the
uniform-expansion gauge conditions, present the Newtonian hydrodynamic
equations in the presence of general relativistic pressure in the zero-shear
gauge, and present the fully nonlinear equations and the third-order
perturbation equations of the nonrelativistic pressure fluids in the
CDM-comoving gauge.
| [
{
"created": "Tue, 3 Nov 2015 05:27:50 GMT",
"version": "v1"
}
] | 2015-11-05 | [
[
"Hwang",
"Jai-chan",
""
],
[
"Noh",
"Hyerim",
""
],
[
"Park",
"Chan-Gyung",
""
]
] | We present fully nonlinear and exact cosmological perturbation equations in the presence of multiple components of fluids and minimally coupled scalar fields. We ignore the tensor-type perturbation. The equations are presented without taking the temporal gauge condition in the Friedmann background with general curvature and the cosmological constant. For each fluid component we ignore the anisotropic stress. The multiple component nature, however, introduces the anisotropic stress in the collective fluid quantities. We prove the Newtonian limit of multiple fluids in the zero-shear gauge and the uniform-expansion gauge conditions, present the Newtonian hydrodynamic equations in the presence of general relativistic pressure in the zero-shear gauge, and present the fully nonlinear equations and the third-order perturbation equations of the nonrelativistic pressure fluids in the CDM-comoving gauge. |
1811.01374 | Thomas Buchert | Asta Heinesen, Pierre Mourier, Thomas Buchert | On the covariance of scalar averaging and backreaction in relativistic
inhomogeneous cosmology | 22 pages; matches published version in CQG | Class. Quantum Grav. 36 (2019) 075001 | 10.1088/1361-6382/ab0618 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We introduce a generalization of the 4-dimensional averaging window function
of Gasperini, Marozzi and Veneziano (2010) that may prove useful for a number
of applications. The covariant nature of spatial scalar averaging schemes to
address the averaging problem in relativistic cosmology is an important
property that is implied by construction, but usually remains implicit. We
employ here the approach of Gasperini et al. for two reasons. First, the
formalism and its generalization presented here are manifestly covariant.
Second, the formalism is convenient for disentangling the dependencies on
foliation, volume measure, and boundaries in the averaged expressions entering
in scalar averaging schemes. These properties will prove handy for simplifying
expressions, but also for investigating extremal foliations and for comparing
averaged properties of different foliations directly. The proposed
generalization of the window function allows for choosing the most appropriate
averaging scheme for the physical problem at hand, and for distinguishing
between the role of the foliation itself and the role of the volume measure in
averaged dynamic equations. We also show that one particular window function
obtained from this generalized class results in an averaging scheme
corresponding to that of a recent investigation by Buchert, Mourier and Roy
(2018) and, as a byproduct, we explicitly show that the general equations for
backreaction derived therein are covariant.
| [
{
"created": "Sun, 4 Nov 2018 14:14:18 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Feb 2019 16:30:24 GMT",
"version": "v2"
}
] | 2019-02-28 | [
[
"Heinesen",
"Asta",
""
],
[
"Mourier",
"Pierre",
""
],
[
"Buchert",
"Thomas",
""
]
] | We introduce a generalization of the 4-dimensional averaging window function of Gasperini, Marozzi and Veneziano (2010) that may prove useful for a number of applications. The covariant nature of spatial scalar averaging schemes to address the averaging problem in relativistic cosmology is an important property that is implied by construction, but usually remains implicit. We employ here the approach of Gasperini et al. for two reasons. First, the formalism and its generalization presented here are manifestly covariant. Second, the formalism is convenient for disentangling the dependencies on foliation, volume measure, and boundaries in the averaged expressions entering in scalar averaging schemes. These properties will prove handy for simplifying expressions, but also for investigating extremal foliations and for comparing averaged properties of different foliations directly. The proposed generalization of the window function allows for choosing the most appropriate averaging scheme for the physical problem at hand, and for distinguishing between the role of the foliation itself and the role of the volume measure in averaged dynamic equations. We also show that one particular window function obtained from this generalized class results in an averaging scheme corresponding to that of a recent investigation by Buchert, Mourier and Roy (2018) and, as a byproduct, we explicitly show that the general equations for backreaction derived therein are covariant. |
1511.03702 | Pierre Fleury | Pierre Fleury | Light propagation in inhomogeneous and anisotropic cosmologies | PhD thesis, 344 pages, contains preprint versions of the articles
arXiv:1302.5308, arXiv:1304.7791, arXiv:1402.3123, arXiv:1406.6254,
arXiv:1410.8473, and arXiv:1508.07903. v2: minor mistake corrected in Sec.
5.2.1 | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The standard model of cosmology is based on the hypothesis that the Universe
is spatially homogeneous and isotropic. When interpreting most observations,
this cosmological principle is applied stricto sensu: the light emitted by
distant sources is assumed to propagate through a Friedmann-Lema\^itre
spacetime. The main goal of the present thesis was to evaluate how reliable
this assumption is, especially when small scales are at stake. After having
reviewed the laws of geometric optics in curved spacetime, and the standard
interpretation of cosmological observables, the dissertation reports a
comprehensive analysis of light propagation in Swiss-cheese models, designed to
capture the clumpy character of the Universe. The resulting impact on the
interpretation of the Hubble diagram is quantified, and shown to be relatively
small, thanks to the cosmological constant. When applied to current supernova
data, the associated corrections tend however to improve the agreement between
the cosmological parameters inferred from the Hubble diagram and from the
cosmic microwave background. This is a hint that the effect of small-scale
structures on light propagation may become non-negligible in the era of
precision cosmology. This motivated the development of a new theoretical
framework, based on stochastic processes, which aims at describing small-scale
gravitational lensing with a better accuracy. Regarding the isotropy side of
the cosmological principle, this dissertation addresses, on the one hand, the
potential effect of a large-scale anisotropy on light propagation, by solving
all the equations of geometric optics in the Bianchi I spacetime. On the other
hand, possible sources of such an anisotropy, namely scalar-vector models for
inflation or dark energy, are analysed. Most of them turn out to be excluded as
physically viable theories.
| [
{
"created": "Tue, 10 Nov 2015 15:14:02 GMT",
"version": "v1"
},
{
"created": "Fri, 12 Jan 2024 12:46:45 GMT",
"version": "v2"
}
] | 2024-01-15 | [
[
"Fleury",
"Pierre",
""
]
] | The standard model of cosmology is based on the hypothesis that the Universe is spatially homogeneous and isotropic. When interpreting most observations, this cosmological principle is applied stricto sensu: the light emitted by distant sources is assumed to propagate through a Friedmann-Lema\^itre spacetime. The main goal of the present thesis was to evaluate how reliable this assumption is, especially when small scales are at stake. After having reviewed the laws of geometric optics in curved spacetime, and the standard interpretation of cosmological observables, the dissertation reports a comprehensive analysis of light propagation in Swiss-cheese models, designed to capture the clumpy character of the Universe. The resulting impact on the interpretation of the Hubble diagram is quantified, and shown to be relatively small, thanks to the cosmological constant. When applied to current supernova data, the associated corrections tend however to improve the agreement between the cosmological parameters inferred from the Hubble diagram and from the cosmic microwave background. This is a hint that the effect of small-scale structures on light propagation may become non-negligible in the era of precision cosmology. This motivated the development of a new theoretical framework, based on stochastic processes, which aims at describing small-scale gravitational lensing with a better accuracy. Regarding the isotropy side of the cosmological principle, this dissertation addresses, on the one hand, the potential effect of a large-scale anisotropy on light propagation, by solving all the equations of geometric optics in the Bianchi I spacetime. On the other hand, possible sources of such an anisotropy, namely scalar-vector models for inflation or dark energy, are analysed. Most of them turn out to be excluded as physically viable theories. |
2012.12189 | Nicolas Herman | Nicolas Herman, Andr\'e F\"uzfa, L\'eonard Lehoucq, S\'ebastien Clesse | Detecting Planetary-mass Primordial Black Holes with Resonant
Electromagnetic Gravitational Wave Detectors | 16 pages, 7 figures | Phys. Rev. D 104, 023524 (2021) | 10.1103/PhysRevD.104.023524 | null | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by/4.0/ | The possibility to detect gravitational waves (GW) from planetary-mass
primordial black hole (PBH) binaries with electromagnetic (EM) detectors of
high-frequency GWs is investigated. We consider two patented experimental
designs, based on the inverse Gertsenshtein effect, in which incoming GWs
passing through a static magnetic field induce EM excitations inside either a
TM cavity or a TEM waveguide. The frequency response of the detectors is
computed for post-newtonian GW waveforms. We find that such EM detectors based
on current technology may achieve a strain sensitivity down to $h \sim
10^{-30}$, which generates an EM power variation of $10^{-10}$ W. This allows
the detection of PBH binary mergers of mass around $10^{-5} M_\odot$ if they
constitute more than $0.01$ percent of the dark matter, as suggested by recent
microlensing observations. We envision that this class of detectors could also
be used to detect cosmological GW backgrounds and probe sources in the early
Universe at energies up to the GUT scale.
| [
{
"created": "Tue, 22 Dec 2020 17:31:15 GMT",
"version": "v1"
},
{
"created": "Mon, 21 Jun 2021 14:26:48 GMT",
"version": "v2"
}
] | 2021-07-20 | [
[
"Herman",
"Nicolas",
""
],
[
"Füzfa",
"André",
""
],
[
"Lehoucq",
"Léonard",
""
],
[
"Clesse",
"Sébastien",
""
]
] | The possibility to detect gravitational waves (GW) from planetary-mass primordial black hole (PBH) binaries with electromagnetic (EM) detectors of high-frequency GWs is investigated. We consider two patented experimental designs, based on the inverse Gertsenshtein effect, in which incoming GWs passing through a static magnetic field induce EM excitations inside either a TM cavity or a TEM waveguide. The frequency response of the detectors is computed for post-newtonian GW waveforms. We find that such EM detectors based on current technology may achieve a strain sensitivity down to $h \sim 10^{-30}$, which generates an EM power variation of $10^{-10}$ W. This allows the detection of PBH binary mergers of mass around $10^{-5} M_\odot$ if they constitute more than $0.01$ percent of the dark matter, as suggested by recent microlensing observations. We envision that this class of detectors could also be used to detect cosmological GW backgrounds and probe sources in the early Universe at energies up to the GUT scale. |
2403.08530 | Ioannis Gialamas | Ioannis D. Gialamas, Theodoros Katsoulas, Kyriakos Tamvakis | Inflation and reheating in quadratic metric-affine gravity with
derivative couplings | 21 pages, 9 figures, matches published version | null | null | null | gr-qc astro-ph.CO hep-ph | http://creativecommons.org/licenses/by/4.0/ | Within the framework of metric-affine theories of gravity, where both the
metric and connection are treated as independent variables, we consider actions
quadratic in the Ricci scalar curvature coupled non-minimally to a scalar field
through derivative couplings. Our analysis delves into the inflationary
predictions, revealing their consistency with the latest observational
constraints across a wide range of parameters. This compatibility permits
adjustments such as an increase in the spectral index and a reduction in the
tensor-to-scalar ratio. While we do not propose a specific reheating mechanism,
our analysis demonstrates that within the quadratic model of inflation, the
maximum reheating temperature can reach $\sim 3\times10^{15}\, {\rm GeV}$.
| [
{
"created": "Wed, 13 Mar 2024 13:40:31 GMT",
"version": "v1"
},
{
"created": "Thu, 6 Jun 2024 09:03:39 GMT",
"version": "v2"
}
] | 2024-06-07 | [
[
"Gialamas",
"Ioannis D.",
""
],
[
"Katsoulas",
"Theodoros",
""
],
[
"Tamvakis",
"Kyriakos",
""
]
] | Within the framework of metric-affine theories of gravity, where both the metric and connection are treated as independent variables, we consider actions quadratic in the Ricci scalar curvature coupled non-minimally to a scalar field through derivative couplings. Our analysis delves into the inflationary predictions, revealing their consistency with the latest observational constraints across a wide range of parameters. This compatibility permits adjustments such as an increase in the spectral index and a reduction in the tensor-to-scalar ratio. While we do not propose a specific reheating mechanism, our analysis demonstrates that within the quadratic model of inflation, the maximum reheating temperature can reach $\sim 3\times10^{15}\, {\rm GeV}$. |
1709.04252 | Zhu Yi | Zhu Yi and Yungui Gong | Inflationary attractors from nonminimal coupling | 5 pages, 1 figures, prepared for the proceedings of the International
Conference on Gravitation : Joint Conference of ICGAC-XIII and IK15 | null | 10.1051/epjconf/201816806003 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show explicitly how the E model attractor is obtained from the general
scalar-tensor theory of gravity with arbitrary conformal factors in the strong
coupling limit. By using conformal transformations, any attractor with the
observables $n_s$ and $r$ can be obtained. The existence of attractors imposes
a challenge to distinguish different models.
| [
{
"created": "Wed, 13 Sep 2017 11:07:31 GMT",
"version": "v1"
}
] | 2018-01-24 | [
[
"Yi",
"Zhu",
""
],
[
"Gong",
"Yungui",
""
]
] | We show explicitly how the E model attractor is obtained from the general scalar-tensor theory of gravity with arbitrary conformal factors in the strong coupling limit. By using conformal transformations, any attractor with the observables $n_s$ and $r$ can be obtained. The existence of attractors imposes a challenge to distinguish different models. |
gr-qc/0612182 | Ettore Minguzzi | E. Minguzzi | On the causal properties of warped product spacetimes | 22 pages, 2 figures, uses the package psfrag | Class.Quant.Grav.24:4457-4474,2007 | 10.1088/0264-9381/24/17/012 | null | gr-qc | null | It is shown that the warped product spacetime P=M *_f H, where H is a
complete Riemannian manifold, and the original spacetime M share necessarily
the same causality properties, the only exceptions being the properties of
causal continuity and causal simplicity which present some subtleties. For
instance, it is shown that if diamH=+\infty, the direct product spacetime P=M*H
is causally simple if and only if (M,g) is causally simple, the Lorentzian
distance on M is continuous and any two causally related events at finite
distance are connected by a maximizing geodesic. Similar conditions are found
for the causal continuity property. Some new results concerning the behavior of
the Lorentzian distance on distinguishing, causally continuous, and causally
simple spacetimes are obtained. Finally, a formula which gives the Lorentzian
distance on the direct product in terms of the distances on the two factors
(M,g) and (H,h) is obtained.
| [
{
"created": "Thu, 28 Dec 2006 17:13:29 GMT",
"version": "v1"
},
{
"created": "Wed, 1 Aug 2007 11:45:50 GMT",
"version": "v2"
}
] | 2011-06-24 | [
[
"Minguzzi",
"E.",
""
]
] | It is shown that the warped product spacetime P=M *_f H, where H is a complete Riemannian manifold, and the original spacetime M share necessarily the same causality properties, the only exceptions being the properties of causal continuity and causal simplicity which present some subtleties. For instance, it is shown that if diamH=+\infty, the direct product spacetime P=M*H is causally simple if and only if (M,g) is causally simple, the Lorentzian distance on M is continuous and any two causally related events at finite distance are connected by a maximizing geodesic. Similar conditions are found for the causal continuity property. Some new results concerning the behavior of the Lorentzian distance on distinguishing, causally continuous, and causally simple spacetimes are obtained. Finally, a formula which gives the Lorentzian distance on the direct product in terms of the distances on the two factors (M,g) and (H,h) is obtained. |
2001.10897 | Cecilio Garc\'ia Quir\'os | Cecilio Garc\'ia-Quir\'os and Sascha Husa and Maite Mateu-Lucena and
Angela Borchers | Accelerating the evaluation of inspiral-merger-ringdown waveforms with
adapted grids | null | null | 10.1088/1361-6382/abc36e | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper presents an algorithm to accelerate the evaluation of
inspiral-merger-ringdown waveform models for gravitational wave data analysis.
While the idea can also be applied in the time domain, here we focus on the
frequency domain, which is most typically used to reduced computational cost in
gravitational wave data analysis. Our work extends the idea of multibanding,
which has been developed to accelerate frequency domain waveforms, to include
the merger and ringdown and spherical harmonics beyond the dominant quadrupole
spherical harmonic. The original method is based on a heuristic algorithm based
on the inspiral to de-refine the equi-spaced frequency grid used for data
analysis where a coarser grid is sufficient for accurate evaluation of a
waveform model. Here we use a different criterion, based on the local
interpolation error, which is more flexible and can easily be adapted to
general waveforms, if their phenomenology is understood. We discuss our
implementation in the LIGO Algorithm Library for the PhenomXHM frequency domain
model, and report the acceleration in different parts of the parameter space of
compact binary systems.
| [
{
"created": "Wed, 29 Jan 2020 15:30:11 GMT",
"version": "v1"
}
] | 2021-02-03 | [
[
"García-Quirós",
"Cecilio",
""
],
[
"Husa",
"Sascha",
""
],
[
"Mateu-Lucena",
"Maite",
""
],
[
"Borchers",
"Angela",
""
]
] | This paper presents an algorithm to accelerate the evaluation of inspiral-merger-ringdown waveform models for gravitational wave data analysis. While the idea can also be applied in the time domain, here we focus on the frequency domain, which is most typically used to reduced computational cost in gravitational wave data analysis. Our work extends the idea of multibanding, which has been developed to accelerate frequency domain waveforms, to include the merger and ringdown and spherical harmonics beyond the dominant quadrupole spherical harmonic. The original method is based on a heuristic algorithm based on the inspiral to de-refine the equi-spaced frequency grid used for data analysis where a coarser grid is sufficient for accurate evaluation of a waveform model. Here we use a different criterion, based on the local interpolation error, which is more flexible and can easily be adapted to general waveforms, if their phenomenology is understood. We discuss our implementation in the LIGO Algorithm Library for the PhenomXHM frequency domain model, and report the acceleration in different parts of the parameter space of compact binary systems. |
1403.7754 | Sean McWilliams | Kai Sheng Tai, Sean T. McWilliams, and Frans Pretorius | Detecting gravitational waves from highly eccentric compact binaries | 17 pages, 20 figures | Phys. Rev. D 90, 103001 (2014) | 10.1103/PhysRevD.90.103001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In dense stellar regions, highly eccentric binaries of black holes and
neutron stars can form through various n-body interactions. Such a binary could
emit a significant fraction of its binding energy in a sequence of largely
isolated gravitational wave bursts prior to merger. Given expected black hole
and neutron star masses, many such systems will emit these repeated bursts at
frequencies within the sensitive band of contemporary ground-based
gravitational wave detectors. Unfortunately, existing gravitational wave
searches are ill-suited to detect these signals. In this work, we adapt a
"power stacking" method to the detection of gravitational wave signals from
highly eccentric binaries. We implement this method as an extension of the
Q-transform, a projection onto a multiresolution basis of windowed complex
exponentials that has previously been used to analyze data from the network of
LIGO/Virgo detectors. Our method searches for excess power over an ensemble of
time-frequency tiles. We characterize the performance of our method using Monte
Carlo experiments with signals injected in simulated detector noise. Our
results indicate that the power stacking method achieves substantially better
sensitivity to eccentric binary signals than existing localized burst searches.
| [
{
"created": "Sun, 30 Mar 2014 13:22:28 GMT",
"version": "v1"
}
] | 2014-11-19 | [
[
"Tai",
"Kai Sheng",
""
],
[
"McWilliams",
"Sean T.",
""
],
[
"Pretorius",
"Frans",
""
]
] | In dense stellar regions, highly eccentric binaries of black holes and neutron stars can form through various n-body interactions. Such a binary could emit a significant fraction of its binding energy in a sequence of largely isolated gravitational wave bursts prior to merger. Given expected black hole and neutron star masses, many such systems will emit these repeated bursts at frequencies within the sensitive band of contemporary ground-based gravitational wave detectors. Unfortunately, existing gravitational wave searches are ill-suited to detect these signals. In this work, we adapt a "power stacking" method to the detection of gravitational wave signals from highly eccentric binaries. We implement this method as an extension of the Q-transform, a projection onto a multiresolution basis of windowed complex exponentials that has previously been used to analyze data from the network of LIGO/Virgo detectors. Our method searches for excess power over an ensemble of time-frequency tiles. We characterize the performance of our method using Monte Carlo experiments with signals injected in simulated detector noise. Our results indicate that the power stacking method achieves substantially better sensitivity to eccentric binary signals than existing localized burst searches. |
2110.10147 | Muhammed Saleem C | Muhammed Saleem, Sayantani Datta, K. G. Arun, and B. S. Sathyaprakash | Parametrized tests of post-Newtonian theory using principal component
analysis | 10 pages, 4 figures, 2 tables | null | 10.1103/PhysRevD.105.084062 | null | gr-qc astro-ph.HE | http://creativecommons.org/publicdomain/zero/1.0/ | Searching for departures from general relativity (GR) in more than one
post-Newtonian (PN) phasing coefficients, called a \emph{multi-parameter test},
is known to be ineffective given the sensitivity of the present generation of
gravitational-wave (GW) detectors. Strong degeneracies in the parameter space
make the outcome of the test uninformative. We argue that Principal Component
Analysis (PCA) can remedy this problem by constructing certain linear
combinations of the original PN parameters that are better constrained by
gravitational-wave observations. By analyzing binary black hole events detected
during the first and second observing runs (O1 and O2) of LIGO/Virgo, we show
that the two dominant principal components can capture the essence of a
multi-parameter test. Combining five binary black hole mergers during O1/O2, we
find that the dominant linear combination of the PN coefficients obtained from
PCA is consistent with GR within the 0.38 standard deviation of the posterior
distribution. Furthermore, using a set of simulated \emph{non-GR} signals in
the three-detector LIGO-Virgo network with designed sensitivities, we find that
the method is capable of excluding GR with high confidence as well as
recovering the injected values of the non-GR parameters with good precision.
| [
{
"created": "Tue, 19 Oct 2021 17:58:48 GMT",
"version": "v1"
}
] | 2022-05-11 | [
[
"Saleem",
"Muhammed",
""
],
[
"Datta",
"Sayantani",
""
],
[
"Arun",
"K. G.",
""
],
[
"Sathyaprakash",
"B. S.",
""
]
] | Searching for departures from general relativity (GR) in more than one post-Newtonian (PN) phasing coefficients, called a \emph{multi-parameter test}, is known to be ineffective given the sensitivity of the present generation of gravitational-wave (GW) detectors. Strong degeneracies in the parameter space make the outcome of the test uninformative. We argue that Principal Component Analysis (PCA) can remedy this problem by constructing certain linear combinations of the original PN parameters that are better constrained by gravitational-wave observations. By analyzing binary black hole events detected during the first and second observing runs (O1 and O2) of LIGO/Virgo, we show that the two dominant principal components can capture the essence of a multi-parameter test. Combining five binary black hole mergers during O1/O2, we find that the dominant linear combination of the PN coefficients obtained from PCA is consistent with GR within the 0.38 standard deviation of the posterior distribution. Furthermore, using a set of simulated \emph{non-GR} signals in the three-detector LIGO-Virgo network with designed sensitivities, we find that the method is capable of excluding GR with high confidence as well as recovering the injected values of the non-GR parameters with good precision. |
2103.02365 | Antonio Figura | A. Figura, F. Li, J.-J. Lu, G.F. Burgio, Z.H. Li, H.-J. Schulze | Binary neutron star merger simulations with hot microscopic equations of
state | Version submitted to PRD | Phys. Rev. D 103, 083012 (2021) | 10.1103/PhysRevD.103.083012 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We perform binary neutron star merger simulations using a newly derived set
of finite-temperature equations of state in the Brueckner-Hartree-Fock
approach. We point out the important and opposite roles of finite temperature
and rotation for stellar stability and systematically investigate the
gravitational-wave properties, matter distribution, and ejecta properties in
the postmerger phase for the different cases. The validity of several universal
relations is also examined and the most suitable EOSs are identified.
| [
{
"created": "Wed, 3 Mar 2021 12:38:07 GMT",
"version": "v1"
}
] | 2021-04-21 | [
[
"Figura",
"A.",
""
],
[
"Li",
"F.",
""
],
[
"Lu",
"J. -J.",
""
],
[
"Burgio",
"G. F.",
""
],
[
"Li",
"Z. H.",
""
],
[
"Schulze",
"H. -J.",
""
]
] | We perform binary neutron star merger simulations using a newly derived set of finite-temperature equations of state in the Brueckner-Hartree-Fock approach. We point out the important and opposite roles of finite temperature and rotation for stellar stability and systematically investigate the gravitational-wave properties, matter distribution, and ejecta properties in the postmerger phase for the different cases. The validity of several universal relations is also examined and the most suitable EOSs are identified. |
0906.2120 | Michal Was | Michal Was (LAL), Marie-Anne Bizouard (LAL), Violette Brisson (LAL),
Fabien Cavalier (LAL), Michel Davier (LAL), Patrice Hello (LAL), Nicolas
Leroy (LAL), Florent Robinet (LAL), Vavoulidis Miltiadis (LAL) | On the background estimation by time slides in a network of
gravitational wave detectors | accepted for publication in CQG | Class.Quant.Grav.27:015005,2010 | 10.1088/0264-9381/27/1/015005 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Time shifting the outputs of Gravitational Wave detectors operating in
coincidence is a convenient way to estimate the background in a search for
short duration signals. However this procedure is limited as increasing
indefinitely the number of time shifts does not provide better estimates. We
show that the false alarm rate estimation error saturates with the number of
time shifts. In particular, for detectors with very different trigger rates
this error saturates at a large value. Explicit computations are done for 2
detectors, and for 3 detectors where the detection statistic relies on the
logical ``OR'' of the coincidences of the 3 couples in the network.
| [
{
"created": "Thu, 11 Jun 2009 14:31:18 GMT",
"version": "v1"
},
{
"created": "Wed, 25 Nov 2009 15:16:37 GMT",
"version": "v2"
}
] | 2010-01-06 | [
[
"Was",
"Michal",
"",
"LAL"
],
[
"Bizouard",
"Marie-Anne",
"",
"LAL"
],
[
"Brisson",
"Violette",
"",
"LAL"
],
[
"Cavalier",
"Fabien",
"",
"LAL"
],
[
"Davier",
"Michel",
"",
"LAL"
],
[
"Hello",
"Patrice",
... | Time shifting the outputs of Gravitational Wave detectors operating in coincidence is a convenient way to estimate the background in a search for short duration signals. However this procedure is limited as increasing indefinitely the number of time shifts does not provide better estimates. We show that the false alarm rate estimation error saturates with the number of time shifts. In particular, for detectors with very different trigger rates this error saturates at a large value. Explicit computations are done for 2 detectors, and for 3 detectors where the detection statistic relies on the logical ``OR'' of the coincidences of the 3 couples in the network. |
gr-qc/0405039 | Alan D. Rendall | David Tegankong, Norbert Noutchegueme and Alan D. Rendall | Local existence and continuation criteria for solutions of the
Einstein-Vlasov-scalar field system with surface symmetry | 33 pages, typos corrected, second conclusion of theorem 4.5 and
remark 4.6 removed | J.Hyperbol.Diff.Equat. 1 (2004) 691-724 | null | AEI-2004-037 | gr-qc | null | We prove in the cases of spherical, plane and hyperbolic symmetry a local in
time existence theorem and continuation criteria for cosmological solutions of
the Einstein-Vlasov-scalar field system, with the sources generated by a
distribution function and a scalar field, subject to the Vlasov and wave
equations respectively. This system describes the evolution of self-gravitating
collisionless matter and scalar waves within the context of general relativity.
In the case where the only source is a scalar field it is shown that a global
existence result can be deduced from the general theorem.
| [
{
"created": "Fri, 7 May 2004 10:56:29 GMT",
"version": "v1"
},
{
"created": "Tue, 26 Oct 2004 12:34:54 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Tegankong",
"David",
""
],
[
"Noutchegueme",
"Norbert",
""
],
[
"Rendall",
"Alan D.",
""
]
] | We prove in the cases of spherical, plane and hyperbolic symmetry a local in time existence theorem and continuation criteria for cosmological solutions of the Einstein-Vlasov-scalar field system, with the sources generated by a distribution function and a scalar field, subject to the Vlasov and wave equations respectively. This system describes the evolution of self-gravitating collisionless matter and scalar waves within the context of general relativity. In the case where the only source is a scalar field it is shown that a global existence result can be deduced from the general theorem. |
gr-qc/0005052 | Antonio Teixeira | A.F.F. Teixeira (Centro Brasileiro de Pesquisas Fisicas) | Cosmic crystallography in a circle | 13 pages, 16 figures, corrected commands for graphics | null | null | CBPF-NF-032/00 | gr-qc astro-ph | null | In a circle (an S^1) with circumference 1 assume m objects distributed
pseudo-randomly. In the universal covering R^1 assume the objects replicated
accordingly, and take an interval L>1. In this interval, make the normalized
histogram of the pair separations which are not an integer. The theoretical
(expected) such histogram is obtained in this report, as well as its difference
to a similar histogram for non-replicated objects. The whole study is of
interest for the cosmic crystallography.
| [
{
"created": "Mon, 15 May 2000 13:43:33 GMT",
"version": "v1"
},
{
"created": "Tue, 11 Jul 2000 23:43:48 GMT",
"version": "v2"
},
{
"created": "Tue, 18 Jul 2000 23:09:39 GMT",
"version": "v3"
},
{
"created": "Thu, 5 Oct 2000 03:07:08 GMT",
"version": "v4"
}
] | 2007-05-23 | [
[
"Teixeira",
"A. F. F.",
"",
"Centro Brasileiro de Pesquisas Fisicas"
]
] | In a circle (an S^1) with circumference 1 assume m objects distributed pseudo-randomly. In the universal covering R^1 assume the objects replicated accordingly, and take an interval L>1. In this interval, make the normalized histogram of the pair separations which are not an integer. The theoretical (expected) such histogram is obtained in this report, as well as its difference to a similar histogram for non-replicated objects. The whole study is of interest for the cosmic crystallography. |
2210.10571 | Nicholas Loutrel | Nicholas Loutrel, Paolo Pani, Nicol\'as Yunes | Parameterized Post-Einsteinian Framework for Precessing Binaries | 24 pages, 5 figures, published version | Phys. Rev. D 107, 044046 (2023) | 10.1103/PhysRevD.107.044046 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In general relativity, isolated black holes obey the no hair theorems, which
fix the multipolar structure of their exterior spacetime. However, in modified
gravity, or when the compact objects are not black holes, the exterior
spacetime may have a different multipolar structure. When two black holes are
in a binary, this multipolar structure determines the morphology of the
dynamics of orbital and spin precession. In turn, the precession dynamics
imprint onto the gravitational waves emitted by an inspiraling compact binary
through specific amplitude and phase modulations. The detection and
characterization of these amplitude and phase modulations can therefore lead to
improved constraints on fundamental physics with gravitational waves. Recently,
analytic precessing waveforms were calculated in two scenarios: (i) dynamical
Chern-Simons gravity, where the no-hair theorems are violated, and (ii)
deformed compact objects with generic mass quadrupole moments. In this work, we
use these two examples to propose an extension of the parameterized
post-Einsteinian~(ppE) framework to include precession effects. The new
framework contains $2n$ ppE parameters $(\mathscr{b}^{\rm ppE}_{(m',n)}, b^{\rm
ppE}_{(m',n)})$ for the waveform phase, and $2n$ ppE parameters
$(\mathscr{a}^{\rm ppE}_{(m',n)}, a^{\rm ppE}_{(m',n)})$ for the waveform
amplitudes. The number of ppE corrections $n$ corresponds to the minimum number
of harmonics necessary to achieve a given likelihood threshold when comparing
the truncated ppE waveform with the exact one, and $(m',n)$ corresponds to the
harmonic numbers of the harmonics containing ppE parameters. We show explicitly
how these ppE parameters map to the specific example waveforms discussed above.
The proposed ppE framework can serve as a basis for future tests of general
relativity with gravitational waves from precessing binaries.
| [
{
"created": "Wed, 19 Oct 2022 14:11:45 GMT",
"version": "v1"
},
{
"created": "Wed, 22 Feb 2023 09:16:05 GMT",
"version": "v2"
}
] | 2023-02-23 | [
[
"Loutrel",
"Nicholas",
""
],
[
"Pani",
"Paolo",
""
],
[
"Yunes",
"Nicolás",
""
]
] | In general relativity, isolated black holes obey the no hair theorems, which fix the multipolar structure of their exterior spacetime. However, in modified gravity, or when the compact objects are not black holes, the exterior spacetime may have a different multipolar structure. When two black holes are in a binary, this multipolar structure determines the morphology of the dynamics of orbital and spin precession. In turn, the precession dynamics imprint onto the gravitational waves emitted by an inspiraling compact binary through specific amplitude and phase modulations. The detection and characterization of these amplitude and phase modulations can therefore lead to improved constraints on fundamental physics with gravitational waves. Recently, analytic precessing waveforms were calculated in two scenarios: (i) dynamical Chern-Simons gravity, where the no-hair theorems are violated, and (ii) deformed compact objects with generic mass quadrupole moments. In this work, we use these two examples to propose an extension of the parameterized post-Einsteinian~(ppE) framework to include precession effects. The new framework contains $2n$ ppE parameters $(\mathscr{b}^{\rm ppE}_{(m',n)}, b^{\rm ppE}_{(m',n)})$ for the waveform phase, and $2n$ ppE parameters $(\mathscr{a}^{\rm ppE}_{(m',n)}, a^{\rm ppE}_{(m',n)})$ for the waveform amplitudes. The number of ppE corrections $n$ corresponds to the minimum number of harmonics necessary to achieve a given likelihood threshold when comparing the truncated ppE waveform with the exact one, and $(m',n)$ corresponds to the harmonic numbers of the harmonics containing ppE parameters. We show explicitly how these ppE parameters map to the specific example waveforms discussed above. The proposed ppE framework can serve as a basis for future tests of general relativity with gravitational waves from precessing binaries. |
1010.1302 | Massimo Tinto | Massimo Tinto and M\'arcio Eduardo da Silva Alves | LISA Sensitivities to Gravitational Waves from Relativistic Metric
Theories of Gravity | Paper submitted to Physical Review D. It is 20 pages long and
contains 14 figures | Phys.Rev.D82:122003,2010 | 10.1103/PhysRevD.82.122003 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The direct observation of gravitational waves will provide a unique tool for
probing the dynamical properties of highly compact astrophysical objects,
mapping ultra-relativistic regions of space-time, and testing Einstein's
general theory of relativity. LISA (Laser Interferometer Space Antenna), a
joint NASA-ESA mission to be launched in the next decade, will perform these
scientific tasks by detecting and studying low-frequency cosmic gravitational
waves through their influence on the phases of six modulated laser beams
exchanged between three remote spacecraft. By directly measuring the
polarization components of the waves LISA will detect, we will be able to test
Einstein's theory of relativity with good sensitivity. Since a gravitational
wave signal predicted by the most general relativistic metric theory of gravity
accounts for {\it six} polarization modes (the usual two Einstein's tensor
polarizations as well as two vector and two scalar wave components), we have
derived the LISA Time-Delay Interferometric responses and estimated their
sensitivities to vector- and scalar-type waves. We find that (i) at frequencies
larger than roughly the inverse of the one-way light time ($\approx 6 \times
10^{-2} $ Hz.) LISA is more than ten times sensitive to scalar-longitudinal and
vector signals than to tensor and scalar-transverse waves, and (ii) in the low
part of its frequency band is equally sensitive to tensor and vector waves and
somewhat less sensitive to scalar signals.
| [
{
"created": "Wed, 6 Oct 2010 23:33:59 GMT",
"version": "v1"
}
] | 2011-01-17 | [
[
"Tinto",
"Massimo",
""
],
[
"Alves",
"Márcio Eduardo da Silva",
""
]
] | The direct observation of gravitational waves will provide a unique tool for probing the dynamical properties of highly compact astrophysical objects, mapping ultra-relativistic regions of space-time, and testing Einstein's general theory of relativity. LISA (Laser Interferometer Space Antenna), a joint NASA-ESA mission to be launched in the next decade, will perform these scientific tasks by detecting and studying low-frequency cosmic gravitational waves through their influence on the phases of six modulated laser beams exchanged between three remote spacecraft. By directly measuring the polarization components of the waves LISA will detect, we will be able to test Einstein's theory of relativity with good sensitivity. Since a gravitational wave signal predicted by the most general relativistic metric theory of gravity accounts for {\it six} polarization modes (the usual two Einstein's tensor polarizations as well as two vector and two scalar wave components), we have derived the LISA Time-Delay Interferometric responses and estimated their sensitivities to vector- and scalar-type waves. We find that (i) at frequencies larger than roughly the inverse of the one-way light time ($\approx 6 \times 10^{-2} $ Hz.) LISA is more than ten times sensitive to scalar-longitudinal and vector signals than to tensor and scalar-transverse waves, and (ii) in the low part of its frequency band is equally sensitive to tensor and vector waves and somewhat less sensitive to scalar signals. |
1607.07791 | Kirill Bronnikov | K.A. Bronnikov, A.M. Galiakhmetov | Wormholes and black universes without phantom fields in Einstein-Cartan
theory | 10 pages, 6 figures | Phys. Rev. D 94, 124006 (2016) | 10.1103/PhysRevD.94.124006 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We obtain a family of regular static, spherically symmetric solutions in
Einstein--Cartan theory with an electromagnetic field and a nonminimally
coupled scalar field with the correct sign of kinetic energy density. At
different values of its parameters, the solution, being asemptotically flat at
large values of the radial coordinate, describes (i) twice asemptotically flat
symmetric wormholes, (ii) asymmetric wormholes with an AdS asymptotic at the
"far end", (iii) regular black holes with an extremal horizon or two simple
horizons, and (iv) black universes with a de Sitter asymptotic at the "far
end". As in other black universe models, it is a black hole as seen by a
distant observer, but beyond its horizon there is a nonsingular expanding
universe. In all these cases, both the metric and the torsion are regular in
the whole space.
| [
{
"created": "Tue, 26 Jul 2016 16:39:46 GMT",
"version": "v1"
}
] | 2016-12-07 | [
[
"Bronnikov",
"K. A.",
""
],
[
"Galiakhmetov",
"A. M.",
""
]
] | We obtain a family of regular static, spherically symmetric solutions in Einstein--Cartan theory with an electromagnetic field and a nonminimally coupled scalar field with the correct sign of kinetic energy density. At different values of its parameters, the solution, being asemptotically flat at large values of the radial coordinate, describes (i) twice asemptotically flat symmetric wormholes, (ii) asymmetric wormholes with an AdS asymptotic at the "far end", (iii) regular black holes with an extremal horizon or two simple horizons, and (iv) black universes with a de Sitter asymptotic at the "far end". As in other black universe models, it is a black hole as seen by a distant observer, but beyond its horizon there is a nonsingular expanding universe. In all these cases, both the metric and the torsion are regular in the whole space. |
1607.04473 | Kai Lin | Kai Lin, Wei-Liang Qian, A. B. Pavan and E. Abdalla | (Anti-) de Sitter Electrically Charged Black Hole Solutions in
Higher-Derivative Gravity | null | Europhysics Letters, 114, 60006 (2016) | 10.1209/0295-5075/114/60006 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, static electrically charged black hole solutions with
cosmological constant are investigated in an Einstein-Hilbert theory of gravity
with additional quadratic curvature terms. Beside the analytic Schwarzschild
(Anti-) de Sitter solutions, non-Schwarzschild (Anti-) de Sitter solutions are
also obtained numerically by employing the shooting method. The results show
that there exist two groups of asymptotically (Anti-) de Sitter spacetimes for
both charged and uncharged black holes. In particular, it was found that for
uncharged black holes the first group can be reduced to the Schwarzschild
(Anti-) de Sitter solution, while the second group is intrinsically different
from a Schwarzschild (Anti-) de Sitter solution even when the charge and the
cosmological constant become zero.
| [
{
"created": "Fri, 15 Jul 2016 11:56:27 GMT",
"version": "v1"
}
] | 2016-07-18 | [
[
"Lin",
"Kai",
""
],
[
"Qian",
"Wei-Liang",
""
],
[
"Pavan",
"A. B.",
""
],
[
"Abdalla",
"E.",
""
]
] | In this paper, static electrically charged black hole solutions with cosmological constant are investigated in an Einstein-Hilbert theory of gravity with additional quadratic curvature terms. Beside the analytic Schwarzschild (Anti-) de Sitter solutions, non-Schwarzschild (Anti-) de Sitter solutions are also obtained numerically by employing the shooting method. The results show that there exist two groups of asymptotically (Anti-) de Sitter spacetimes for both charged and uncharged black holes. In particular, it was found that for uncharged black holes the first group can be reduced to the Schwarzschild (Anti-) de Sitter solution, while the second group is intrinsically different from a Schwarzschild (Anti-) de Sitter solution even when the charge and the cosmological constant become zero. |
1901.08391 | David Brizuela | David Brizuela, Unai Muniain | A moment approach to compute quantum-gravity effects in the primordial
universe | 22 pages, 2 figures | JCAP 04 (2019) 016 | 10.1088/1475-7516/2019/04/016 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An approach to compute quantum-gravity corrections to the scalar and
tensorial power spectra of the inflationary perturbations is presented. The
analysis of the Wheeler-DeWitt equation is performed by a decomposition of the
wave function into its infinite set of moments, which must obey certain system
of (first-class) constraints. Considering a semiclassical approximation, the
system is truncated at second order in moments and an appropriate gauge-fixing
condition is introduced, which allows us to interpret the scale factor of the
universe as an internal time. The evolution of the different fluctuations and
correlations is then explicitly considered for a de Sitter universe. An
approximate analytical solution is obtained for the corrections of the power
spectra, which produces an enhancement of power for large scales. Remarkably,
the result is in agreement with previous studies in the literature that made
use of very different semiclassical approximations. Finally, the numerical
implementation of the system is also considered to verify the validity of the
analytical solution.
| [
{
"created": "Thu, 24 Jan 2019 13:13:08 GMT",
"version": "v1"
},
{
"created": "Tue, 9 Apr 2019 15:37:41 GMT",
"version": "v2"
}
] | 2019-04-10 | [
[
"Brizuela",
"David",
""
],
[
"Muniain",
"Unai",
""
]
] | An approach to compute quantum-gravity corrections to the scalar and tensorial power spectra of the inflationary perturbations is presented. The analysis of the Wheeler-DeWitt equation is performed by a decomposition of the wave function into its infinite set of moments, which must obey certain system of (first-class) constraints. Considering a semiclassical approximation, the system is truncated at second order in moments and an appropriate gauge-fixing condition is introduced, which allows us to interpret the scale factor of the universe as an internal time. The evolution of the different fluctuations and correlations is then explicitly considered for a de Sitter universe. An approximate analytical solution is obtained for the corrections of the power spectra, which produces an enhancement of power for large scales. Remarkably, the result is in agreement with previous studies in the literature that made use of very different semiclassical approximations. Finally, the numerical implementation of the system is also considered to verify the validity of the analytical solution. |
1811.11694 | Jonas Pedro Pereira | Jonas P. Pereira, Germ\'an Lugones | General relativistic surface degrees of freedom in perturbed hybrid
stars | 8 pages. Accepted for publication in ApJ | null | 10.3847/1538-4357/aaf4ba | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study how the nature of a hybrid system (perfect fluid, solid or a mixture
of them) could be related to the induction of general relativistic surface
degrees of freedom on phase-splitting surfaces upon perturbation of its phases.
We work in the scope of phase conversions in the vicinity of sharp phase
transition surfaces whose timescales are either much smaller (rapid
conversions) or larger (slow conversions) than the ones of the perturbations
($\omega^{-1}$, where $\omega$ is a characteristic frequency of oscillation of
the star). In this first approach, perturbations are assumed to be purely
radial. We show that surface degrees of freedom could emerge when either the
core or the crust of a hybrid star is solid and phase conversions close to a
phase-splitting surface are rapid. We also show how this would change the usual
stability rule for solid hybrid stars, namely $\partial M_0/\partial \rho_c\geq
0$, where $M_0$ is the total mass to the background hybrid star and $\rho_c$
its central density. Further consequences of our analysis for asteroseismology
are also briefly discussed.
| [
{
"created": "Wed, 28 Nov 2018 17:25:35 GMT",
"version": "v1"
}
] | 2019-01-30 | [
[
"Pereira",
"Jonas P.",
""
],
[
"Lugones",
"Germán",
""
]
] | We study how the nature of a hybrid system (perfect fluid, solid or a mixture of them) could be related to the induction of general relativistic surface degrees of freedom on phase-splitting surfaces upon perturbation of its phases. We work in the scope of phase conversions in the vicinity of sharp phase transition surfaces whose timescales are either much smaller (rapid conversions) or larger (slow conversions) than the ones of the perturbations ($\omega^{-1}$, where $\omega$ is a characteristic frequency of oscillation of the star). In this first approach, perturbations are assumed to be purely radial. We show that surface degrees of freedom could emerge when either the core or the crust of a hybrid star is solid and phase conversions close to a phase-splitting surface are rapid. We also show how this would change the usual stability rule for solid hybrid stars, namely $\partial M_0/\partial \rho_c\geq 0$, where $M_0$ is the total mass to the background hybrid star and $\rho_c$ its central density. Further consequences of our analysis for asteroseismology are also briefly discussed. |
1305.5203 | Tomasz Pawlowski | Viqar Husain, Tomasz Pawlowski | A computable framework for Loop Quantum Gravity | 3 pages. To appear in Proceedings of the 13th Marcel Grossmann
Meeting (MG13), Stockholm, Sweden, 1-7 July 2012 | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a non-perturbative quantization of general relativity coupled to
dust and other matter fields. The dust provides a natural time variable,
leading to a physical Hamiltonian with spatial diffeomorphism symmetry. The
methods of loop quantum gravity applied to this model lead to a physical
Hilbert space and Hamiltonian. This provides a framework for physical
calculations in the theory.
| [
{
"created": "Wed, 22 May 2013 17:17:23 GMT",
"version": "v1"
}
] | 2013-05-23 | [
[
"Husain",
"Viqar",
""
],
[
"Pawlowski",
"Tomasz",
""
]
] | We present a non-perturbative quantization of general relativity coupled to dust and other matter fields. The dust provides a natural time variable, leading to a physical Hamiltonian with spatial diffeomorphism symmetry. The methods of loop quantum gravity applied to this model lead to a physical Hilbert space and Hamiltonian. This provides a framework for physical calculations in the theory. |
2205.01919 | Igor Bogush M.Sc. | Igor Bogush, Dmitri Gal'tsov, Galin Gyulchev, Kirill Kobialko, Petya
Nedkova, Tsvetan Vetsov | Photon surfaces, shadows and accretion disks in gravity with minimally
coupled scalar field | 62 pages, revtex4, 33 figures | null | 10.1103/PhysRevD.106.024034 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this article, we conduct a sequential study of possible observable images
of black hole simulators described by two recently obtained rotating geometries
in Einstein gravity, minimally coupled to a scalar field. One of them,
"Kerr-like" (KL), can be seen as a legitimate alternative to the rotating
Fisher-Janis-Newman-Winicour (FJNW) solution, and the other (TSL) is a scalar
generalization of the Tomimatsu-Sato solution. Unlike the previous version of
the rotating FJNW, these solutions do indeed satisfy the system's equations of
motion. Our study includes both analytical and numerical calculations of
equatorial circular orbits, photon regions, gravitational shadows, and
radiation from thin accretion disks for various values of the object's angular
momentum and scalar charge. The TSL solution was found to simulate Kerr for all
valid parameter values with high accuracy. The maximum difference between the
deviations of shadows from a circle for the Kerr and TSL cases does not exceed
1% and fits into the experimental observational data M87*. However,
near-extreme objects show two times smaller peak values of the observed outflow
luminosity of the accretion disk than for the Kerr black hole. The KL solution
cannot be ruled out by the experimental data for small values of the scalar
charge either. As the scalar charge increases, the optical properties change
dramatically. The shadow can become multiply connected, strongly oblate, and
the photon region does not hide the singularity, so it should be classified as
a strong singularity.
| [
{
"created": "Wed, 4 May 2022 07:12:51 GMT",
"version": "v1"
}
] | 2022-08-31 | [
[
"Bogush",
"Igor",
""
],
[
"Gal'tsov",
"Dmitri",
""
],
[
"Gyulchev",
"Galin",
""
],
[
"Kobialko",
"Kirill",
""
],
[
"Nedkova",
"Petya",
""
],
[
"Vetsov",
"Tsvetan",
""
]
] | In this article, we conduct a sequential study of possible observable images of black hole simulators described by two recently obtained rotating geometries in Einstein gravity, minimally coupled to a scalar field. One of them, "Kerr-like" (KL), can be seen as a legitimate alternative to the rotating Fisher-Janis-Newman-Winicour (FJNW) solution, and the other (TSL) is a scalar generalization of the Tomimatsu-Sato solution. Unlike the previous version of the rotating FJNW, these solutions do indeed satisfy the system's equations of motion. Our study includes both analytical and numerical calculations of equatorial circular orbits, photon regions, gravitational shadows, and radiation from thin accretion disks for various values of the object's angular momentum and scalar charge. The TSL solution was found to simulate Kerr for all valid parameter values with high accuracy. The maximum difference between the deviations of shadows from a circle for the Kerr and TSL cases does not exceed 1% and fits into the experimental observational data M87*. However, near-extreme objects show two times smaller peak values of the observed outflow luminosity of the accretion disk than for the Kerr black hole. The KL solution cannot be ruled out by the experimental data for small values of the scalar charge either. As the scalar charge increases, the optical properties change dramatically. The shadow can become multiply connected, strongly oblate, and the photon region does not hide the singularity, so it should be classified as a strong singularity. |
1602.05197 | Geoffrey Comp\`ere | Geoffrey Comp\`ere and Jiang Long | Classical static final state of collapse with supertranslation memory | 35 pages, 7 figures, published version (only refs updated with
respect to v2) | null | 10.1088/0264-9381/33/19/195001 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Kerr metric models the final classical black hole state after
gravitational collapse of matter and radiation. Any stationary metric which is
close to the Kerr metric has been proven to be diffeomorphic to it. Now, finite
supertranslation diffeomorphisms are symmetries which map solutions to
inequivalent solutions as such diffeomorphisms generate conserved superrotation
charges. The final state of gravitational collapse is therefore parameterized
by its mass, angular momentum and supertranslation field, signaled by its
conserved superrotation charges.
In this paper, we first derive the angle-dependent energy conservation law
relating the asymptotic value of the supertranslation field of the final state
to the details of the collapse and subsequent evolution of the system. We then
generate the static solution with an asymptotic supertranslation field and we
study some of its properties. Up to a caveat, the deviation from the
Schwarzschild metric could therefore be predicted on a case-by-case basis from
accurate modeling of the angular dependence of the ingoing and outgoing energy
fluxes leading to the final state.
| [
{
"created": "Tue, 16 Feb 2016 21:00:04 GMT",
"version": "v1"
},
{
"created": "Wed, 3 Aug 2016 13:28:37 GMT",
"version": "v2"
},
{
"created": "Mon, 5 Sep 2016 19:31:54 GMT",
"version": "v3"
}
] | 2016-09-21 | [
[
"Compère",
"Geoffrey",
""
],
[
"Long",
"Jiang",
""
]
] | The Kerr metric models the final classical black hole state after gravitational collapse of matter and radiation. Any stationary metric which is close to the Kerr metric has been proven to be diffeomorphic to it. Now, finite supertranslation diffeomorphisms are symmetries which map solutions to inequivalent solutions as such diffeomorphisms generate conserved superrotation charges. The final state of gravitational collapse is therefore parameterized by its mass, angular momentum and supertranslation field, signaled by its conserved superrotation charges. In this paper, we first derive the angle-dependent energy conservation law relating the asymptotic value of the supertranslation field of the final state to the details of the collapse and subsequent evolution of the system. We then generate the static solution with an asymptotic supertranslation field and we study some of its properties. Up to a caveat, the deviation from the Schwarzschild metric could therefore be predicted on a case-by-case basis from accurate modeling of the angular dependence of the ingoing and outgoing energy fluxes leading to the final state. |
0910.4821 | Haitang Yang | De-You Chen, Haitang Yang and Xiao-Tao Zu | Hawking radiation of black holes in the $z = 4$ Horava-Lifshitz gravity | V2: references added, typo corrected, 16pages | Phys.Lett.B681:463-468,2009 | 10.1016/j.physletb.2009.10.065 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the Hawking radiation of 3+1 and 4+1 dimensional black holes
in the $z = 4$ Horava-Lifshitz gravity with fermion tunnelling. It turns out
that the Hawking temperatures are recovered and are in consistence with those
obtained by calculating surface gravity of the black holes. For the 3+1
dimensional black holes, the Hawking temperatures are related to the
fundamental parameters of Horava-Lifshitz gravity.
| [
{
"created": "Mon, 26 Oct 2009 07:49:18 GMT",
"version": "v1"
},
{
"created": "Mon, 9 Nov 2009 06:53:50 GMT",
"version": "v2"
}
] | 2010-02-11 | [
[
"Chen",
"De-You",
""
],
[
"Yang",
"Haitang",
""
],
[
"Zu",
"Xiao-Tao",
""
]
] | We investigate the Hawking radiation of 3+1 and 4+1 dimensional black holes in the $z = 4$ Horava-Lifshitz gravity with fermion tunnelling. It turns out that the Hawking temperatures are recovered and are in consistence with those obtained by calculating surface gravity of the black holes. For the 3+1 dimensional black holes, the Hawking temperatures are related to the fundamental parameters of Horava-Lifshitz gravity. |
2306.10383 | C Fairoos | T. K. Safir, A. Naveena Kumara, Shreyas Punacha, Deepak Vaid, C. L.
Ahmed Rizwan, and C. Fairoos | Dynamic Phase Transition of Black Holes in Massive Gravity | 23 pages, 18 figures. Revised thoroughly after peer review. Accepted
for publication in Annals of Physics | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The dynamical properties of small-large black hole phase transition in dRGT
non-linear massive gravity theory are studied based on the underlying free
energy landscape. The free energy landscape is constructed by specifying the
Gibbs free energy to every state, and the free energy profile is used to study
the different black hole phases. The small-large black hole states are
characterized by probability distribution functions and the kinetics of phase
transition are described by the Fokker-Planck equation. Further, a detailed
study of the first passage process is presented which describes the dynamics of
phase transitions. Finally, we have investigated the effect of mass and
topology on the dynamical properties of phase transitions of black holes in
dRGT non-linear massive gravity theory.
| [
{
"created": "Sat, 17 Jun 2023 15:54:48 GMT",
"version": "v1"
},
{
"created": "Sun, 17 Sep 2023 14:40:35 GMT",
"version": "v2"
}
] | 2023-09-19 | [
[
"Safir",
"T. K.",
""
],
[
"Kumara",
"A. Naveena",
""
],
[
"Punacha",
"Shreyas",
""
],
[
"Vaid",
"Deepak",
""
],
[
"Rizwan",
"C. L. Ahmed",
""
],
[
"Fairoos",
"C.",
""
]
] | The dynamical properties of small-large black hole phase transition in dRGT non-linear massive gravity theory are studied based on the underlying free energy landscape. The free energy landscape is constructed by specifying the Gibbs free energy to every state, and the free energy profile is used to study the different black hole phases. The small-large black hole states are characterized by probability distribution functions and the kinetics of phase transition are described by the Fokker-Planck equation. Further, a detailed study of the first passage process is presented which describes the dynamics of phase transitions. Finally, we have investigated the effect of mass and topology on the dynamical properties of phase transitions of black holes in dRGT non-linear massive gravity theory. |
0908.3205 | Kristin Schleich | Donald M. Witt | Topological Obstructions To Maximal Slices | 19 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A necessary condition for a globally hyperbolic spacetime ${\mathbb R}\times
\Sigma$ to admit a maximal slice is that the Cauchy slice $\Sigma$ admit a
metric with nonnegative scalar curvature, $R\ge 0$. In this paper, the two
cases considered are the closed spatial manifold and the asymptotically flat
spatial manifold. Although most results here will apply in four or more
spacetime dimensions, this work will mainly consider 4-dimensional spacetimes.
For $\Sigma$ closed or asymptotically flat, all topologies are allowed by the
field equations. Since all $\Sigma$ occur as Cauchy slices of solutions to the
Einstein equations and most $\Sigma$ do not admit metrics with $R\ge 0$, it
follows that most globally hyperbolic spacetimes never admit a maximal slice,
i.e. a slice with zero mean extrinsic curvature. In particular, asymptotically
flat globally hyperbolic spacetimes which admit maximal slices are the
exception rather than the rule. The reason for this is due to topological
obstructions to constructing such slices. In the asymptotically flat case, this
will be shown by smooth compactification of the manifold in order to use the
results for spatially closed manifolds.
| [
{
"created": "Fri, 21 Aug 2009 20:58:46 GMT",
"version": "v1"
}
] | 2009-08-25 | [
[
"Witt",
"Donald M.",
""
]
] | A necessary condition for a globally hyperbolic spacetime ${\mathbb R}\times \Sigma$ to admit a maximal slice is that the Cauchy slice $\Sigma$ admit a metric with nonnegative scalar curvature, $R\ge 0$. In this paper, the two cases considered are the closed spatial manifold and the asymptotically flat spatial manifold. Although most results here will apply in four or more spacetime dimensions, this work will mainly consider 4-dimensional spacetimes. For $\Sigma$ closed or asymptotically flat, all topologies are allowed by the field equations. Since all $\Sigma$ occur as Cauchy slices of solutions to the Einstein equations and most $\Sigma$ do not admit metrics with $R\ge 0$, it follows that most globally hyperbolic spacetimes never admit a maximal slice, i.e. a slice with zero mean extrinsic curvature. In particular, asymptotically flat globally hyperbolic spacetimes which admit maximal slices are the exception rather than the rule. The reason for this is due to topological obstructions to constructing such slices. In the asymptotically flat case, this will be shown by smooth compactification of the manifold in order to use the results for spatially closed manifolds. |
2407.14305 | Hidetomo Hoshino Mr. | Hidetomo Hoshino, Takuya Tsuchiya, Gen Yoneda | Stability analysis and improvement of the covariant BSSN formulation
against the FLRW spacetime background | 16 pages, 3 figures | null | null | null | gr-qc cs.NA math.NA | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this study, we investigate the numerical stability of the covariant
Baumgarte--Shapiro--Shibata--Nakamura (cBSSN) formulation against the
Friedmann--Lema\^itre--Robertson--Walker spacetime. To evaluate the numerical
stability, we calculate the constraint amplification factor by the eigenvalue
analysis of the evolution of the constraint. We propose a modification to the
time evolution equations of the cBSSN formulation for a higher numerical
stability. Furthermore, we perform numerical simulations using the modified
formulation to confirm its improved stability.
| [
{
"created": "Fri, 19 Jul 2024 13:35:52 GMT",
"version": "v1"
}
] | 2024-07-22 | [
[
"Hoshino",
"Hidetomo",
""
],
[
"Tsuchiya",
"Takuya",
""
],
[
"Yoneda",
"Gen",
""
]
] | In this study, we investigate the numerical stability of the covariant Baumgarte--Shapiro--Shibata--Nakamura (cBSSN) formulation against the Friedmann--Lema\^itre--Robertson--Walker spacetime. To evaluate the numerical stability, we calculate the constraint amplification factor by the eigenvalue analysis of the evolution of the constraint. We propose a modification to the time evolution equations of the cBSSN formulation for a higher numerical stability. Furthermore, we perform numerical simulations using the modified formulation to confirm its improved stability. |
1710.06607 | Michal Bejger | Michal Bejger | Status of the continuous gravitational wave searches in the Advanced
Detector Era | 8 pages, 3 figures (summary talk at the Rencontres de Moriond 2017
Gravitation session) | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Periodic (almost monochromatic) gravitational waves emitted by rotating,
asymmetric neutron stars are intriguing potential signals in the sensitivity
band of Advanced LIGO and Advanced Virgo detectors. These signals are related
to elastic and magnetic stresses in the neutron-star interior, as well as to
various possible instabilities, and thus are interesting from the point of view
of the largely-unknown neutron star structure. I will describe the main
challenges related to these searches, the current state of the data-analysis
methods and plans for the future.
| [
{
"created": "Wed, 18 Oct 2017 07:48:29 GMT",
"version": "v1"
}
] | 2017-10-19 | [
[
"Bejger",
"Michal",
""
]
] | Periodic (almost monochromatic) gravitational waves emitted by rotating, asymmetric neutron stars are intriguing potential signals in the sensitivity band of Advanced LIGO and Advanced Virgo detectors. These signals are related to elastic and magnetic stresses in the neutron-star interior, as well as to various possible instabilities, and thus are interesting from the point of view of the largely-unknown neutron star structure. I will describe the main challenges related to these searches, the current state of the data-analysis methods and plans for the future. |
2109.05027 | Jo\~ao M. Oliveira | Carlos A. R. Herdeiro, Jo\~ao M. S. Oliveira, Alexandre M. Pombo,
Eugen Radu | Virial identities in relativistic gravity: 1D effective actions and the
role of boundary terms | 27 pages, 1 figure | null | 10.1103/PhysRevD.104.104051 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Virial (aka scaling) identities are integral identities that are useful for a
variety of purposes in non-linear field theories, including establishing no-go
theorems for solitonic and black hole solutions, as well as for checking the
accuracy of numerical solutions. In this paper, we provide a pedagogical
rationale for the derivation of such integral identities, starting from the
standard variational treatment of particle mechanics. In the framework of
one-dimensional (1D) effective actions, the treatment presented here yields a
set of useful formulas for computing virial identities in any field theory.
Then, we propose that a complete treatment of virial identities in relativistic
gravity must take into account the appropriate boundary term. For General
Relativity this is the Gibbons-Hawking-York boundary term. We test and confirm
this proposal with concrete examples. Our analysis here is restricted to
spherically symmetric configurations, which yield 1D effective actions (leaving
higher-D effective actions and in particular the axially symmetric case to a
companion paper). In this case, we show that there is a particular "gauge"
choice, $i.e.$ a choice of coordinates and parameterizing metric functions,
that simplifies the computation of virial identities in General Relativity,
making both the Einstein-Hilbert action and the Gibbons-Hawking-York boundary
term non-contributing. Under this choice, the virial identity results
exclusively from the matter action. For generic "gauge" choices, however, this
is not the case.
| [
{
"created": "Fri, 10 Sep 2021 18:00:01 GMT",
"version": "v1"
}
] | 2021-12-01 | [
[
"Herdeiro",
"Carlos A. R.",
""
],
[
"Oliveira",
"João M. S.",
""
],
[
"Pombo",
"Alexandre M.",
""
],
[
"Radu",
"Eugen",
""
]
] | Virial (aka scaling) identities are integral identities that are useful for a variety of purposes in non-linear field theories, including establishing no-go theorems for solitonic and black hole solutions, as well as for checking the accuracy of numerical solutions. In this paper, we provide a pedagogical rationale for the derivation of such integral identities, starting from the standard variational treatment of particle mechanics. In the framework of one-dimensional (1D) effective actions, the treatment presented here yields a set of useful formulas for computing virial identities in any field theory. Then, we propose that a complete treatment of virial identities in relativistic gravity must take into account the appropriate boundary term. For General Relativity this is the Gibbons-Hawking-York boundary term. We test and confirm this proposal with concrete examples. Our analysis here is restricted to spherically symmetric configurations, which yield 1D effective actions (leaving higher-D effective actions and in particular the axially symmetric case to a companion paper). In this case, we show that there is a particular "gauge" choice, $i.e.$ a choice of coordinates and parameterizing metric functions, that simplifies the computation of virial identities in General Relativity, making both the Einstein-Hilbert action and the Gibbons-Hawking-York boundary term non-contributing. Under this choice, the virial identity results exclusively from the matter action. For generic "gauge" choices, however, this is not the case. |
2006.10991 | Christiane Klein | Stefan Hollands, Christiane Klein and Jochen Zahn | Quantum stress tensor at the Cauchy horizon of
Reissner-Nordstr\"om-deSitter spacetime | Correction to eq. 28; version as published in Phys.Rev.D | Phys.Rev.D 102 (2020) 085004 | 10.1103/PhysRevD.102.085004 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The strong cosmic censorship conjecture proposes that starting from generic
initial data on some Cauchy surface, the solutions of the Einstein equation
should not be extendable across the boundary of the domain of dependence of
that surface. For the case of the Reissner-Nordstr\"om-de Sitter spacetime this
means that any perturbation should blow up sufficiently badly when approaching
this boundary, called the Cauchy horizon. However, recent results indicate that
for highly charged black holes classical scalar perturbations allow for a
violation of strong cosmic censorship. In a recent paper arXiv:1912.06047, two
of us have argued that quantum effects will restore censorship for generic
values of the black hole parameters. But, due to practical limitations, the
precise form of the divergence was only calculated for a small number of
parameters. Here we perform a thorough parameter scan using an alternative,
more efficient semi-analytic method. Our analysis confirms arXiv:1912.06047 in
the sense that the quantum stress tensor is found to diverge badly generically.
However, the sign of the divergence can be changed by changing the mass of the
field or the spacetime parameters, leading to a drastically different type of
singularity on the Cauchy horizon.
| [
{
"created": "Fri, 19 Jun 2020 07:38:45 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Oct 2020 11:13:02 GMT",
"version": "v2"
}
] | 2020-10-15 | [
[
"Hollands",
"Stefan",
""
],
[
"Klein",
"Christiane",
""
],
[
"Zahn",
"Jochen",
""
]
] | The strong cosmic censorship conjecture proposes that starting from generic initial data on some Cauchy surface, the solutions of the Einstein equation should not be extendable across the boundary of the domain of dependence of that surface. For the case of the Reissner-Nordstr\"om-de Sitter spacetime this means that any perturbation should blow up sufficiently badly when approaching this boundary, called the Cauchy horizon. However, recent results indicate that for highly charged black holes classical scalar perturbations allow for a violation of strong cosmic censorship. In a recent paper arXiv:1912.06047, two of us have argued that quantum effects will restore censorship for generic values of the black hole parameters. But, due to practical limitations, the precise form of the divergence was only calculated for a small number of parameters. Here we perform a thorough parameter scan using an alternative, more efficient semi-analytic method. Our analysis confirms arXiv:1912.06047 in the sense that the quantum stress tensor is found to diverge badly generically. However, the sign of the divergence can be changed by changing the mass of the field or the spacetime parameters, leading to a drastically different type of singularity on the Cauchy horizon. |
2004.10505 | Jose Natario | Carolina Figueiredo and Jos\'e Nat\'ario | Riemannian manifolds dual to static spacetimes | 18 pages, 9 figures; v2: minor changes, references added, matches
final published version | Gen. Rel. Grav. 52 (2020) 84 | 10.1007/s10714-020-02736-5 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We establish a one-to-one correspondence between static spacetimes and
Riemannian manifolds that maps causal geodesics to geodesics, as suggested by
L. C. Epstein. We then explore constant curvature spacetimes - such as the de
Sitter and the anti-de Sitter universes - and find that they map to constant
curvature Riemannian manifolds, namely the Euclidean space, the sphere and the
hyperbolic space. By imposing the conditions required to map to the sphere, we
obtain the spherically symmetric metrics for which there is radial oscillatory
motion with a period independent of the amplitude. We then consider the case of
a perfect fluid and an Einstein cluster and determine the pressure and density
profiles required to find this type of motion. Finally, we give examples of
surfaces corresponding to certain types of motion for metrics that do not
exhibit constant curvature, such as the Schwarzschild, Schwarzschild de Sitter
and Schwarzschild anti-de Sitter solutions, and even for a simplified model of
a wormhole.
| [
{
"created": "Wed, 22 Apr 2020 11:37:41 GMT",
"version": "v1"
},
{
"created": "Mon, 7 Sep 2020 08:11:03 GMT",
"version": "v2"
}
] | 2020-09-22 | [
[
"Figueiredo",
"Carolina",
""
],
[
"Natário",
"José",
""
]
] | We establish a one-to-one correspondence between static spacetimes and Riemannian manifolds that maps causal geodesics to geodesics, as suggested by L. C. Epstein. We then explore constant curvature spacetimes - such as the de Sitter and the anti-de Sitter universes - and find that they map to constant curvature Riemannian manifolds, namely the Euclidean space, the sphere and the hyperbolic space. By imposing the conditions required to map to the sphere, we obtain the spherically symmetric metrics for which there is radial oscillatory motion with a period independent of the amplitude. We then consider the case of a perfect fluid and an Einstein cluster and determine the pressure and density profiles required to find this type of motion. Finally, we give examples of surfaces corresponding to certain types of motion for metrics that do not exhibit constant curvature, such as the Schwarzschild, Schwarzschild de Sitter and Schwarzschild anti-de Sitter solutions, and even for a simplified model of a wormhole. |
1206.4003 | Edward Anderson | Edward Anderson | Kerr-Newman Black Hole Thermodynamical State Space: Blockwise
Coordinates | 4 pages incl 2 figs. Accepted by Gen. Rel. Grav. Replaced with
Accepted version (minor corrections) | null | 10.1007/s10714-013-1603-0 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A coordinate system that blockwise-simplifies the Kerr-Newman black hole's
thermodynamical state space Ruppeiner metric geometry is constructed, with
discussion of the limiting cases corresponding to simpler black holes. It is
deduced that one of the three conformal Killing vectors of the
Reissner-Nordstrom and Kerr cases (whose thermodynamical state space metrics
are 2 by 2 and conformally flat) survives generalization to the Kerr-Newman
case's 3 by 3 thermodynamical state space metric.
| [
{
"created": "Mon, 18 Jun 2012 17:46:19 GMT",
"version": "v1"
},
{
"created": "Wed, 3 Apr 2013 20:13:38 GMT",
"version": "v2"
},
{
"created": "Wed, 7 Aug 2013 14:21:29 GMT",
"version": "v3"
},
{
"created": "Fri, 11 Oct 2013 17:00:57 GMT",
"version": "v4"
},
{
"cre... | 2015-06-05 | [
[
"Anderson",
"Edward",
""
]
] | A coordinate system that blockwise-simplifies the Kerr-Newman black hole's thermodynamical state space Ruppeiner metric geometry is constructed, with discussion of the limiting cases corresponding to simpler black holes. It is deduced that one of the three conformal Killing vectors of the Reissner-Nordstrom and Kerr cases (whose thermodynamical state space metrics are 2 by 2 and conformally flat) survives generalization to the Kerr-Newman case's 3 by 3 thermodynamical state space metric. |
gr-qc/9610013 | Lars Andersson | Lars Andersson, Vincent Moncrief, Anthony J. Tromba | On the global evolution problem in 2+1 gravity | 14 pages, amsart | null | 10.1016/S0393-0440(97)87804-7 | null | gr-qc | null | Existence of global CMC foliations of constant curvature 3-dimensional
maximal globally hyperbolic Lorentzian manifolds, containing a constant mean
curvature hypersurface with $\genus(\Sigma) > 1$ is proved. Constant curvature
3-dimensional Lorentzian manifolds can be viewed as solutions to the 2+1 vacuum
Einstein equations with a cosmological constant. The proof is based on the
reduction of the corresponding Hamiltonian system in constant mean curvature
gauge to a time dependent Hamiltonian system on the cotangent bundle of
Teichm\"uller space. Estimates of the Dirichlet energy of the induced metric
play an essential role in the proof.
| [
{
"created": "Thu, 10 Oct 1996 02:30:03 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Andersson",
"Lars",
""
],
[
"Moncrief",
"Vincent",
""
],
[
"Tromba",
"Anthony J.",
""
]
] | Existence of global CMC foliations of constant curvature 3-dimensional maximal globally hyperbolic Lorentzian manifolds, containing a constant mean curvature hypersurface with $\genus(\Sigma) > 1$ is proved. Constant curvature 3-dimensional Lorentzian manifolds can be viewed as solutions to the 2+1 vacuum Einstein equations with a cosmological constant. The proof is based on the reduction of the corresponding Hamiltonian system in constant mean curvature gauge to a time dependent Hamiltonian system on the cotangent bundle of Teichm\"uller space. Estimates of the Dirichlet energy of the induced metric play an essential role in the proof. |
1405.1865 | Arijit Bhattacharyay | Supratik Sarkar and A. Bhattacharyay | Quantum potential induced emergence of massive scalar fields in the
analogue gravity model of a Bose-Einstein condensate | 5 pages, no figures | null | null | null | gr-qc cond-mat.other | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show here a general approach to include the quantum potential term in the
emergent gravity model of Bose-Einstein condensate by using multiple scales.
Our main result shows the emergence of a massive scalar modulating field at
larger length scales as a result of Lorentz symmetry breaking at the length
scales comparable to the healing length. We also propose that, the nonlocal
interactions induced tuning of healing length can be exploited experimentally
to observe the systematics of small and large scale coupling as emerges in our
present analysis.
| [
{
"created": "Thu, 8 May 2014 10:10:35 GMT",
"version": "v1"
},
{
"created": "Tue, 3 Jun 2014 07:20:30 GMT",
"version": "v2"
},
{
"created": "Mon, 9 Jun 2014 12:13:33 GMT",
"version": "v3"
},
{
"created": "Fri, 5 Sep 2014 05:06:18 GMT",
"version": "v4"
}
] | 2014-09-08 | [
[
"Sarkar",
"Supratik",
""
],
[
"Bhattacharyay",
"A.",
""
]
] | We show here a general approach to include the quantum potential term in the emergent gravity model of Bose-Einstein condensate by using multiple scales. Our main result shows the emergence of a massive scalar modulating field at larger length scales as a result of Lorentz symmetry breaking at the length scales comparable to the healing length. We also propose that, the nonlocal interactions induced tuning of healing length can be exploited experimentally to observe the systematics of small and large scale coupling as emerges in our present analysis. |
1908.10602 | Shayesteh Ghaffari | S. Ghaffari, E. Sadri and A. H. Ziaie | Tsallis holographic dark energy in Fractal Universe | 9 pages, 6 figures | null | 10.1142/S0217732320501072 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the cosmological consequences of interacting Tsallis holographic
dark energy model in the framework of the fractal universe, in which, the
Hubble radius is considered as the IR cut-off. We drive the equation of state
(EoS) parameter, deceleration parameter and the evolution equation for the
Tsallis holographic dark energy density parameter. Our study shows that this
model can describe the current accelerating Universe in both noninteracting and
interacting scenarios, and also a transition occurs from the deceleration phase
to the accelerated phase, at the late time. Finally, we check the compatibility
of free parameters of the model with the latest observational results by using
the Pantheon supernovae data, eBOSS, 6df, BOSS DR12, CMB Planck 2015, Gamma-Ray
Burst.
| [
{
"created": "Wed, 28 Aug 2019 09:08:21 GMT",
"version": "v1"
}
] | 2020-06-24 | [
[
"Ghaffari",
"S.",
""
],
[
"Sadri",
"E.",
""
],
[
"Ziaie",
"A. H.",
""
]
] | We study the cosmological consequences of interacting Tsallis holographic dark energy model in the framework of the fractal universe, in which, the Hubble radius is considered as the IR cut-off. We drive the equation of state (EoS) parameter, deceleration parameter and the evolution equation for the Tsallis holographic dark energy density parameter. Our study shows that this model can describe the current accelerating Universe in both noninteracting and interacting scenarios, and also a transition occurs from the deceleration phase to the accelerated phase, at the late time. Finally, we check the compatibility of free parameters of the model with the latest observational results by using the Pantheon supernovae data, eBOSS, 6df, BOSS DR12, CMB Planck 2015, Gamma-Ray Burst. |
1503.05061 | Koray D\"uzta\c{s} | Koray D\"uzta\c{s} | Is there a mode stability paradox for neutrino perturbations of Kerr
black holes? | Major changes, published version | Phys. Rev. D, Vol. 94, 044025, (2016) | 10.1103/PhysRevD.94.044025 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Adopting the notation of Teukolsky and Press, we derive the connection
relation for asymptotic solutions of the massless Dirac equation on a Kerr
background. We show that, unlike bosonic fields, the connection relation for
massless Dirac fields (neutrino) provides a rigorous proof of mode stability.
The same relation also implies that every incoming mode can be absorbed by the
black hole or there is no superradiance. Recent works on overspinning black
holes have shown that this can lead to the formation of naked singularities. We
argue that the fact that both the mode stability of the black hole under
neutrino perturbations and the instability of the event horizon (therefore the
instability of the black hole) can be derived from the same connection relation
leads to a paradox. In other words mode, stability implies event horizon
instability as far as neutrino perturbations are concerned.
| [
{
"created": "Tue, 17 Mar 2015 14:14:10 GMT",
"version": "v1"
},
{
"created": "Thu, 14 May 2015 12:10:56 GMT",
"version": "v2"
},
{
"created": "Mon, 15 Aug 2016 14:45:55 GMT",
"version": "v3"
}
] | 2016-08-16 | [
[
"Düztaş",
"Koray",
""
]
] | Adopting the notation of Teukolsky and Press, we derive the connection relation for asymptotic solutions of the massless Dirac equation on a Kerr background. We show that, unlike bosonic fields, the connection relation for massless Dirac fields (neutrino) provides a rigorous proof of mode stability. The same relation also implies that every incoming mode can be absorbed by the black hole or there is no superradiance. Recent works on overspinning black holes have shown that this can lead to the formation of naked singularities. We argue that the fact that both the mode stability of the black hole under neutrino perturbations and the instability of the event horizon (therefore the instability of the black hole) can be derived from the same connection relation leads to a paradox. In other words mode, stability implies event horizon instability as far as neutrino perturbations are concerned. |
2102.00496 | Daniel Su\'arez-Urango | D. Su\'arez-Urango (1), L. A. N\'u\~nez (1 and 2), H. Hern\'andez (1
and 2) ((1) Universidad Industrial de Santander, (2) Universidad de los
Andes) | Relativistic Anisotropic Polytropic Spheres: Physical Acceptability | 6 pages, 2 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we evaluate the physical acceptability of relativistic
anisotropic spheres modeled by two polytropic equations of state -- with the
same newtonian limit -- commonly used to describe compact objects in General
Relativity. We integrate numerically the corresponding Lane-Emden equation in
order to get density, mass and pressure profiles. An ansatz is used for the
anisotropic pressure allowing us to have material configurations slightly
deviated from isotropic condition. Numerical models are classified in a
parameter space according to the number of physical acceptability conditions
that they fulfil. We found that the polytropes considering total energy density
are more stable than the second type of polytropic EoS.
| [
{
"created": "Sun, 31 Jan 2021 17:30:55 GMT",
"version": "v1"
}
] | 2021-02-02 | [
[
"Suárez-Urango",
"D.",
"",
"1 and 2"
],
[
"Núñez",
"L. A.",
"",
"1 and 2"
],
[
"Hernández",
"H.",
"",
"1\n and 2"
]
] | In this work we evaluate the physical acceptability of relativistic anisotropic spheres modeled by two polytropic equations of state -- with the same newtonian limit -- commonly used to describe compact objects in General Relativity. We integrate numerically the corresponding Lane-Emden equation in order to get density, mass and pressure profiles. An ansatz is used for the anisotropic pressure allowing us to have material configurations slightly deviated from isotropic condition. Numerical models are classified in a parameter space according to the number of physical acceptability conditions that they fulfil. We found that the polytropes considering total energy density are more stable than the second type of polytropic EoS. |
2103.07675 | Nigel Bishop | Nigel T. Bishop | Introduction to gravitational wave astronomy | To be published in "Handbook of Gravitational Wave Astronomy" | null | 10.1007/978-981-15-4702-7_1-1 | null | gr-qc | http://creativecommons.org/licenses/by-nc-nd/4.0/ | This chapter provides an overview of gravitational wave (GW) astronomy,
providing background material that underpins the other, more specialized
chapters in this handbook. It starts with a brief historical review of the
development of GW astronomy, from Einstein's prediction of GWs in 1916 to the
first direct detection in 2015. It presents the theory of linearized
perturbations about Minkowski spacetime of Einstein's equations, and shows how
gauge transformations reduce the problem to the standard wave equation with two
degrees of freedom, or polarizations, $h_+,h_\times$. We derive the quadrupole
formula, which relates the motion of matter in a source region to the far GW
field. It is shown that GWs carry energy, as well as linear and angular
momentum, away from a source. The GW field of an orbiting circular binary is
found; and properties of the evolution of the binary including rate of inspiral
and time to coalescence, are calculated. A brief review is given of existing
and proposed GW detectors, and of how to estimate source parameters in LIGO or
Virgo data of a GW event. The contributions that GW observations have already
made to physics, astrophysics and cosmology are discussed.
| [
{
"created": "Sat, 13 Mar 2021 10:31:21 GMT",
"version": "v1"
}
] | 2022-07-20 | [
[
"Bishop",
"Nigel T.",
""
]
] | This chapter provides an overview of gravitational wave (GW) astronomy, providing background material that underpins the other, more specialized chapters in this handbook. It starts with a brief historical review of the development of GW astronomy, from Einstein's prediction of GWs in 1916 to the first direct detection in 2015. It presents the theory of linearized perturbations about Minkowski spacetime of Einstein's equations, and shows how gauge transformations reduce the problem to the standard wave equation with two degrees of freedom, or polarizations, $h_+,h_\times$. We derive the quadrupole formula, which relates the motion of matter in a source region to the far GW field. It is shown that GWs carry energy, as well as linear and angular momentum, away from a source. The GW field of an orbiting circular binary is found; and properties of the evolution of the binary including rate of inspiral and time to coalescence, are calculated. A brief review is given of existing and proposed GW detectors, and of how to estimate source parameters in LIGO or Virgo data of a GW event. The contributions that GW observations have already made to physics, astrophysics and cosmology are discussed. |
gr-qc/0511049 | Edward Glass | Selcuk Bayin, E.N. Glass, Jean P. Krisch | Fractional Boundaries for Fluid Spheres | to appear in J. Math. Phys | J.Math.Phys.47:012501,2006 | 10.1063/1.2158436 | null | gr-qc | null | A single Israel layer can be created when two metrics adjoin with no
continuous metric derivative across the boundary. The properties of the layer
depend only on the two metrics it separates. By using a fractional derivative
match, a family of Israel layers can be created between the same two metrics.
The family is indexed by the order of the fractional derivative. The method is
applied to Tolman IV and V interiors and a Schwarzschild vacuum exterior. The
method creates new ranges of modeling parameters for fluid spheres. A thin
shell analysis clarifies pressure/tension in the family of boundary layers.
| [
{
"created": "Wed, 9 Nov 2005 20:32:39 GMT",
"version": "v1"
},
{
"created": "Fri, 11 Nov 2005 04:13:42 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Bayin",
"Selcuk",
""
],
[
"Glass",
"E. N.",
""
],
[
"Krisch",
"Jean P.",
""
]
] | A single Israel layer can be created when two metrics adjoin with no continuous metric derivative across the boundary. The properties of the layer depend only on the two metrics it separates. By using a fractional derivative match, a family of Israel layers can be created between the same two metrics. The family is indexed by the order of the fractional derivative. The method is applied to Tolman IV and V interiors and a Schwarzschild vacuum exterior. The method creates new ranges of modeling parameters for fluid spheres. A thin shell analysis clarifies pressure/tension in the family of boundary layers. |
1603.04115 | Cosimo Bambi | Alejandro Cardenas-Avendano, Jiachen Jiang, Cosimo Bambi | A study for testing the Kerr metric with AGN iron line eclipses | 1+15 pages, 8 figures. v2: refereed version | JCAP 1604:054,2016 | 10.1088/1475-7516/2016/04/054 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, two of us have studied iron line reverberation mapping to test
black hole candidates, showing that the time information in reverberation
mapping can better constrain the Kerr metric than the time-integrated approach.
Motivated by this finding, here we explore the constraining power of another
time-dependent measurement: an AGN iron line eclipse. An obscuring cloud passes
between the AGN and the distant observer, covering different parts of the
accretion disk at different times. Similar to the reverberation measurement, an
eclipse might help to better identify the relativistic effects affecting the
X-ray photons. However, this is not what we find. In our study, we employ the
Johannsen-Psaltis parametrisation, but we argue that our conclusions hold in a
large class of non-Kerr metrics. We explain our results pointing out an
important difference between reverberation and eclipse measurements.
| [
{
"created": "Mon, 14 Mar 2016 03:02:42 GMT",
"version": "v1"
},
{
"created": "Thu, 21 Apr 2016 06:36:50 GMT",
"version": "v2"
}
] | 2016-04-29 | [
[
"Cardenas-Avendano",
"Alejandro",
""
],
[
"Jiang",
"Jiachen",
""
],
[
"Bambi",
"Cosimo",
""
]
] | Recently, two of us have studied iron line reverberation mapping to test black hole candidates, showing that the time information in reverberation mapping can better constrain the Kerr metric than the time-integrated approach. Motivated by this finding, here we explore the constraining power of another time-dependent measurement: an AGN iron line eclipse. An obscuring cloud passes between the AGN and the distant observer, covering different parts of the accretion disk at different times. Similar to the reverberation measurement, an eclipse might help to better identify the relativistic effects affecting the X-ray photons. However, this is not what we find. In our study, we employ the Johannsen-Psaltis parametrisation, but we argue that our conclusions hold in a large class of non-Kerr metrics. We explain our results pointing out an important difference between reverberation and eclipse measurements. |
2405.04921 | Xiao Yan Chew | Xiao Yan Chew, Yun Soo Myung | The simplest model of a scalarized black hole in the
Einstein-Klein-Gordon theory | 18 pages with 8 figures (To match with the published version) | null | 10.1103/PhysRevD.110.044011 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We investigate scalarized black holes in the Einstein-minimally coupled
scalar theory with a negative potential $V(\phi)=-\alpha^2\phi^6$. The
tachyonic instability is absent from analyzing the linearized scalar equation,
which could not allow for spontaneous scalarization. However, we obtain the
black hole solutions with scalar hair by solving three full equations because
this scalar potential violates the weak energy condition. This shows clearly
that scalarized black holes can be obtained without introducing a non-minimal
scalar coupling term. We perform the stability analysis for scalarized black
holes by adopting radial perturbations, implying that all scalarized black
holes belonging to a single branch are unstable.
| [
{
"created": "Wed, 8 May 2024 09:42:44 GMT",
"version": "v1"
},
{
"created": "Mon, 20 May 2024 03:52:04 GMT",
"version": "v2"
},
{
"created": "Mon, 12 Aug 2024 07:39:56 GMT",
"version": "v3"
}
] | 2024-08-13 | [
[
"Chew",
"Xiao Yan",
""
],
[
"Myung",
"Yun Soo",
""
]
] | We investigate scalarized black holes in the Einstein-minimally coupled scalar theory with a negative potential $V(\phi)=-\alpha^2\phi^6$. The tachyonic instability is absent from analyzing the linearized scalar equation, which could not allow for spontaneous scalarization. However, we obtain the black hole solutions with scalar hair by solving three full equations because this scalar potential violates the weak energy condition. This shows clearly that scalarized black holes can be obtained without introducing a non-minimal scalar coupling term. We perform the stability analysis for scalarized black holes by adopting radial perturbations, implying that all scalarized black holes belonging to a single branch are unstable. |
1812.11862 | Shanzhong Han | Shan-Zhong Han, Jie Jiang, Ming Zhang, Wen-Biao Liu | Photon sphere and phase transition of $d$-dimensional ($d\ge5$) charged
Gauss-Bonnet AdS black holes | 8 pages, 15 figures | null | 10.1088/1572-9494/aba259 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Motivated by recent work, nonmonotonic behaviours of photon sphere radius can
be used to reflect black hole phase transition for
Reissner-Nordstr$\ddot{o}$m-AdS (RN-AdS) black holes, we study the case of
five-dimensional charged Gauss-Bonnet-AdS (GB-AdS) black holes in the reduced
parameter space. We find that the nonmonotonic behaviours of photon sphere
radius still exist. Using the coexistence line calculated from $P-V$ plane, we
capture the photon sphere radius of saturated small and large black holes (the
boundary of the coexistence phase), then illustrate the reduced coexistence
region. The results show that, reduced coexistence region decreases with charge
$Q$ but increases with Gauss-Bonnet coefficient $\alpha$. When the charge
vanishes, reduced coexistence region doesn't vary with Gauss-Bonnet coefficient
$\alpha$ any more. In this case, the Gauss-Bonnet coefficient $\alpha$ plays
the same role as the charge of five-dimensional RN-AdS black holes. Also, the
situation of higher dimension is studied in the end.
| [
{
"created": "Thu, 27 Dec 2018 18:33:20 GMT",
"version": "v1"
},
{
"created": "Tue, 1 Jan 2019 20:16:09 GMT",
"version": "v2"
},
{
"created": "Mon, 5 Oct 2020 20:43:23 GMT",
"version": "v3"
},
{
"created": "Wed, 7 Oct 2020 08:42:36 GMT",
"version": "v4"
}
] | 2020-10-08 | [
[
"Han",
"Shan-Zhong",
""
],
[
"Jiang",
"Jie",
""
],
[
"Zhang",
"Ming",
""
],
[
"Liu",
"Wen-Biao",
""
]
] | Motivated by recent work, nonmonotonic behaviours of photon sphere radius can be used to reflect black hole phase transition for Reissner-Nordstr$\ddot{o}$m-AdS (RN-AdS) black holes, we study the case of five-dimensional charged Gauss-Bonnet-AdS (GB-AdS) black holes in the reduced parameter space. We find that the nonmonotonic behaviours of photon sphere radius still exist. Using the coexistence line calculated from $P-V$ plane, we capture the photon sphere radius of saturated small and large black holes (the boundary of the coexistence phase), then illustrate the reduced coexistence region. The results show that, reduced coexistence region decreases with charge $Q$ but increases with Gauss-Bonnet coefficient $\alpha$. When the charge vanishes, reduced coexistence region doesn't vary with Gauss-Bonnet coefficient $\alpha$ any more. In this case, the Gauss-Bonnet coefficient $\alpha$ plays the same role as the charge of five-dimensional RN-AdS black holes. Also, the situation of higher dimension is studied in the end. |
1308.1233 | Iftikhar Ahmad | Iftikhar Ahmad, Maqsoom Fatima and Najam-ul-Basat | Static Solutions of Einstein's Equations with Spherical Symmetry | 10 pages,3 figures. arXiv admin note: substantial text overlap with
arXiv:1101.4668 by other authors | J. Theor. Phys. 2 (2013)39-48 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Schwarzschild solution is a complete solution of Einstein's field
equations for a static spherically symmetric field. The Einstein's field
equations solutions appear in the literature, but in different ways
corresponding to different definitions of the radial coordinate. We attempt to
compare them to the solutions with nonvanishing energy density and pressure. We
also calculate some special cases with changes in spherical symmetry.
| [
{
"created": "Tue, 6 Aug 2013 10:56:06 GMT",
"version": "v1"
},
{
"created": "Fri, 2 May 2014 06:58:32 GMT",
"version": "v2"
}
] | 2014-05-05 | [
[
"Ahmad",
"Iftikhar",
""
],
[
"Fatima",
"Maqsoom",
""
],
[
"Najam-ul-Basat",
"",
""
]
] | The Schwarzschild solution is a complete solution of Einstein's field equations for a static spherically symmetric field. The Einstein's field equations solutions appear in the literature, but in different ways corresponding to different definitions of the radial coordinate. We attempt to compare them to the solutions with nonvanishing energy density and pressure. We also calculate some special cases with changes in spherical symmetry. |
1304.4237 | Shohreh Abdolrahimi | Shohreh Abdolrahimi | Velocity Effects on an Accelerated Unruh-DeWitt Detector | (7 pages) | Class. Quantum Grav. 31 135009 (2014) | 10.1088/0264-9381/31/13/135009 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyze the response of an Unruh-DeWitt detector moving along an unbounded
spatial trajectory in a two-dimensional spatial plane with constant independent
magnitudes of both the four-acceleration and of a timelike proper time
derivative of the four-accelration. In a Fermi-Walker frame moving with the
detector, the direction of the acceleration rotates at a constant rate around a
great circle. This is the motion of a charge in a uniform electric field when
in the frame of the charge there is both an electric and a magnetic field. We
compare the response of this detector to a detector moving with constant
velocity in a thermal bath of the corresponding temperature for
non-relativistic velocities, and in two regimes: ultraviolet and infrared. In
infrared regime, the detector in the Minkowski space-time moving along the
spatially two-dimensional trajectory should move with a higher speed to keep up
with the same excitation rate of the inertial detector in a thermal bath. In
ultraviolet regime, the dominant modification in the response of this detector
compared to the black body spectrum of Unruh radiation is the same as the
dominant modification perceived by a detector moving with constant velocity in
a thermal bath.
| [
{
"created": "Mon, 15 Apr 2013 20:00:11 GMT",
"version": "v1"
}
] | 2014-06-17 | [
[
"Abdolrahimi",
"Shohreh",
""
]
] | We analyze the response of an Unruh-DeWitt detector moving along an unbounded spatial trajectory in a two-dimensional spatial plane with constant independent magnitudes of both the four-acceleration and of a timelike proper time derivative of the four-accelration. In a Fermi-Walker frame moving with the detector, the direction of the acceleration rotates at a constant rate around a great circle. This is the motion of a charge in a uniform electric field when in the frame of the charge there is both an electric and a magnetic field. We compare the response of this detector to a detector moving with constant velocity in a thermal bath of the corresponding temperature for non-relativistic velocities, and in two regimes: ultraviolet and infrared. In infrared regime, the detector in the Minkowski space-time moving along the spatially two-dimensional trajectory should move with a higher speed to keep up with the same excitation rate of the inertial detector in a thermal bath. In ultraviolet regime, the dominant modification in the response of this detector compared to the black body spectrum of Unruh radiation is the same as the dominant modification perceived by a detector moving with constant velocity in a thermal bath. |
gr-qc/9912029 | Peter Robert Williams | P. R. Williams, B. F. Schutz | An efficient Matched Filtering Algorithm for the Detection of Continuous
Gravitational Wave Signals | 4 pages, text only, accepted for publication in the proceedings of
the 3rd Amaldi conference on gravitational waves | null | 10.1063/1.1291918 | null | gr-qc | null | We describe an efficient method of matched filtering over long (greater than
1 day) time baselines starting from Fourier transforms of short durations
(roughly 30 minutes) of the data stream. This method plays a crucial role in
the search algorithm developed by Schutz and Papa for the detection of
continuous gravitational waves from pulsars. Also, we discuss the computational
cost--saving approximations used in this method, and the resultant performance
of the search algorithm.
| [
{
"created": "Wed, 8 Dec 1999 14:11:31 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Williams",
"P. R.",
""
],
[
"Schutz",
"B. F.",
""
]
] | We describe an efficient method of matched filtering over long (greater than 1 day) time baselines starting from Fourier transforms of short durations (roughly 30 minutes) of the data stream. This method plays a crucial role in the search algorithm developed by Schutz and Papa for the detection of continuous gravitational waves from pulsars. Also, we discuss the computational cost--saving approximations used in this method, and the resultant performance of the search algorithm. |
gr-qc/9403037 | null | P.F. Gonzalez-Diaz | Radiation Field on Superspace | 13, IMAFF-RC-01-94# | null | null | null | gr-qc | null | We study the dynamics of multiwormhole configurations within the framework of
the Euclidean Polyakov approach to string theory, incorporating a modification
to the Hamiltonian which makes it impossible to interpret the Coleman Alpha
parameters of the effective interactions as a quantum field on superspace,
reducible to an infinite tower of fields on space-time. We obtain a Planckian
probability measure for the Alphas that allows $\frac{1}{2}\alpha^{2}$ to be
interpreted as the energy of the quanta of a radiation field on superspace
whose values may still fix the coupling constants.
| [
{
"created": "Fri, 18 Mar 1994 17:11:05 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Gonzalez-Diaz",
"P. F.",
""
]
] | We study the dynamics of multiwormhole configurations within the framework of the Euclidean Polyakov approach to string theory, incorporating a modification to the Hamiltonian which makes it impossible to interpret the Coleman Alpha parameters of the effective interactions as a quantum field on superspace, reducible to an infinite tower of fields on space-time. We obtain a Planckian probability measure for the Alphas that allows $\frac{1}{2}\alpha^{2}$ to be interpreted as the energy of the quanta of a radiation field on superspace whose values may still fix the coupling constants. |
1105.0765 | Laszlo Arpad Gergely | Zsolt Horv\'ath, L\'aszl\'o \'A. Gergely, Zolt\'an Keresztes, Tiberiu
Harko, Francisco S. N. Lobo | Constraining Ho\v{r}ava-Lifshitz gravity by weak and strong
gravitational lensing | 11 pages, 6 figures, introductory part and reference list changed on
referee request, results expanded. Published version | Phys.Rev.D84:083006,2011 | 10.1103/PhysRevD.84.083006 | null | gr-qc astro-ph.GA hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss gravitational lensing in the Kehagias-Sfetsos space-time emerging
in the framework of Ho\v{r}ava-Lifshitz gravity. In weak lensing we show that
there are three regimes, depending on the value of $\bar {\lambda}=1/\omega
d^{2}$, where $\omega $ is the Ho\v{r}ava-Lifshitz parameter and $d$
characterizes the lensing geometry. When $\bar {\lambda}$ is close to zero,
light deflection typically produces two images, as in Schwarzschild lensing.
For very large $\bar {\lambda}$ the space-time approaches flatness, therefore
there is only one undeflected image. In the intermediate range of $\bar
{\lambda}$ only the upper focused image is produced due to the existence of a
maximal deflection angle $\delta_{max}$, a feature inexistent in the
Schwarzschild weak lensing. We also discuss the location of Einstein rings, and
determine the range of the Ho\v{r}ava-Lifshitz parameter compatible with
present day lensing observations. Finally, we analyze in the strong lensing
regime the first two relativistic Einstein rings and determine the constraints
on the parameter range to be imposed by forthcoming experiments.
| [
{
"created": "Wed, 4 May 2011 08:47:48 GMT",
"version": "v1"
},
{
"created": "Thu, 12 May 2011 08:10:27 GMT",
"version": "v2"
},
{
"created": "Thu, 13 Oct 2011 11:57:50 GMT",
"version": "v3"
}
] | 2011-10-14 | [
[
"Horváth",
"Zsolt",
""
],
[
"Gergely",
"László Á.",
""
],
[
"Keresztes",
"Zoltán",
""
],
[
"Harko",
"Tiberiu",
""
],
[
"Lobo",
"Francisco S. N.",
""
]
] | We discuss gravitational lensing in the Kehagias-Sfetsos space-time emerging in the framework of Ho\v{r}ava-Lifshitz gravity. In weak lensing we show that there are three regimes, depending on the value of $\bar {\lambda}=1/\omega d^{2}$, where $\omega $ is the Ho\v{r}ava-Lifshitz parameter and $d$ characterizes the lensing geometry. When $\bar {\lambda}$ is close to zero, light deflection typically produces two images, as in Schwarzschild lensing. For very large $\bar {\lambda}$ the space-time approaches flatness, therefore there is only one undeflected image. In the intermediate range of $\bar {\lambda}$ only the upper focused image is produced due to the existence of a maximal deflection angle $\delta_{max}$, a feature inexistent in the Schwarzschild weak lensing. We also discuss the location of Einstein rings, and determine the range of the Ho\v{r}ava-Lifshitz parameter compatible with present day lensing observations. Finally, we analyze in the strong lensing regime the first two relativistic Einstein rings and determine the constraints on the parameter range to be imposed by forthcoming experiments. |
2305.17411 | Yiqian Chen | Yiqian Chen, Peng Wang, Houwen Wu, Haitang Yang | Gravitational Lensing by Born-Infeld Naked Singularities | 7 figures, 2 tables | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We examine the gravitational lensing phenomenon caused by photon spheres in
the Born-Infeld naked singularity spacetime, where gravity is coupled with
Born-Infeld electrodynamics. Specifically, our focus lies on relativistic
images originating from a point-like light source generated by strong
gravitational lensing near photon spheres, as well as images of a luminous
celestial sphere. It shows that Born-Infeld naked singularities consistently
exhibit one or two photon spheres, which project onto one or two critical
curves on the image plane. Interestingly, we discover that the nonlinearity
nature of the Born-Infeld electrodynamics enables photons to traverse the
singularity, leading to the emergence of new relativistic images within the
innermost critical curve. Furthermore, the presence of two photon spheres
doubles the number of relativistic images compared to the scenario with only a
single photon sphere. Additionally, the transparency inherent to Born-Infeld
naked singularities results in the absence of a central shadow in the images of
celestial spheres.
| [
{
"created": "Sat, 27 May 2023 08:34:00 GMT",
"version": "v1"
}
] | 2023-05-30 | [
[
"Chen",
"Yiqian",
""
],
[
"Wang",
"Peng",
""
],
[
"Wu",
"Houwen",
""
],
[
"Yang",
"Haitang",
""
]
] | We examine the gravitational lensing phenomenon caused by photon spheres in the Born-Infeld naked singularity spacetime, where gravity is coupled with Born-Infeld electrodynamics. Specifically, our focus lies on relativistic images originating from a point-like light source generated by strong gravitational lensing near photon spheres, as well as images of a luminous celestial sphere. It shows that Born-Infeld naked singularities consistently exhibit one or two photon spheres, which project onto one or two critical curves on the image plane. Interestingly, we discover that the nonlinearity nature of the Born-Infeld electrodynamics enables photons to traverse the singularity, leading to the emergence of new relativistic images within the innermost critical curve. Furthermore, the presence of two photon spheres doubles the number of relativistic images compared to the scenario with only a single photon sphere. Additionally, the transparency inherent to Born-Infeld naked singularities results in the absence of a central shadow in the images of celestial spheres. |
1504.03545 | Luca Fabbri | Luca Fabbri, Stefano Vignolo | A torsional completion of gravity for Dirac matter fields and its
applications to neutrino oscillations | 4 pages | Mod.Phys.Lett.A31:1650014(2016) | 10.1142/S0217732316500140 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we consider the torsional completion of gravitation for an
underlying background filled with Dirac fields, applying it to the problem of
neutrino oscillations: we discuss the effects of the induced torsional
interactions as corrections to the neutrino oscillation mechanism.
| [
{
"created": "Tue, 14 Apr 2015 13:51:10 GMT",
"version": "v1"
},
{
"created": "Sat, 9 Jan 2016 03:27:47 GMT",
"version": "v2"
}
] | 2016-01-26 | [
[
"Fabbri",
"Luca",
""
],
[
"Vignolo",
"Stefano",
""
]
] | In this paper, we consider the torsional completion of gravitation for an underlying background filled with Dirac fields, applying it to the problem of neutrino oscillations: we discuss the effects of the induced torsional interactions as corrections to the neutrino oscillation mechanism. |
2102.10816 | Margaret Millhouse | Yi Shuen C. Lee, Margaret Millhouse, Andrew Melatos | Enhancing gravitational-wave burst detection confidence in expanded
detector networks with the BayesWave pipeline | 13 pages, 7 figures, accepted for publication in Physical Review D | null | 10.1103/PhysRevD.103.062002 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The global gravitational-wave detector network achieves higher detection
rates, better parameter estimates, and more accurate sky localisation, as the
number of detectors, $\mathcal{I}$ increases. This paper quantifies network
performance as a function of $\mathcal{I}$ for BayesWave, a source-agnostic,
wavelet-based, Bayesian algorithm which distinguishes between true
astrophysical signals and instrumental glitches. Detection confidence is
quantified using the signal-to-glitch Bayes factor,
$\mathcal{B}_{\mathcal{S},\mathcal{G}}$. An analytic scaling is derived for
$\mathcal{B}_{\mathcal{S},\mathcal{G}}$ versus $\mathcal{I}$, the number of
wavelets, and the network signal-to-noise ratio, SNR$_\text{net}$, which is
confirmed empirically via injections into detector noise of the
Hanford-Livingston (HL), Hanford-Livingston-Virgo (HLV), and
Hanford-Livingston-KAGRA-Virgo (HLKV) networks at projected sensitivities for
the fourth observing run (O4). The empirical and analytic scalings are
consistent; $\mathcal{B}_{\mathcal{S},\mathcal{G}}$ increases with
$\mathcal{I}$. The accuracy of waveform reconstruction is quantified using the
overlap between injected and recovered waveform, $\mathcal{O}_\text{net}$. The
HLV and HLKV network recovers $87\%$ and $86\%$ of the injected waveforms with
$\mathcal{O}_\text{net}>0.8$ respectively, compared to $81\%$ with the HL
network. The accuracy of BayesWave sky localisation is $\approx 10$ times
better for the HLV network than the HL network, as measured by the search area,
$\mathcal{A}$, and the sky areas contained within $50\%$ and $90\%$ confidence
intervals. Marginal improvement in sky localisation is also observed with the
addition of KAGRA.
| [
{
"created": "Mon, 22 Feb 2021 08:07:39 GMT",
"version": "v1"
}
] | 2021-03-31 | [
[
"Lee",
"Yi Shuen C.",
""
],
[
"Millhouse",
"Margaret",
""
],
[
"Melatos",
"Andrew",
""
]
] | The global gravitational-wave detector network achieves higher detection rates, better parameter estimates, and more accurate sky localisation, as the number of detectors, $\mathcal{I}$ increases. This paper quantifies network performance as a function of $\mathcal{I}$ for BayesWave, a source-agnostic, wavelet-based, Bayesian algorithm which distinguishes between true astrophysical signals and instrumental glitches. Detection confidence is quantified using the signal-to-glitch Bayes factor, $\mathcal{B}_{\mathcal{S},\mathcal{G}}$. An analytic scaling is derived for $\mathcal{B}_{\mathcal{S},\mathcal{G}}$ versus $\mathcal{I}$, the number of wavelets, and the network signal-to-noise ratio, SNR$_\text{net}$, which is confirmed empirically via injections into detector noise of the Hanford-Livingston (HL), Hanford-Livingston-Virgo (HLV), and Hanford-Livingston-KAGRA-Virgo (HLKV) networks at projected sensitivities for the fourth observing run (O4). The empirical and analytic scalings are consistent; $\mathcal{B}_{\mathcal{S},\mathcal{G}}$ increases with $\mathcal{I}$. The accuracy of waveform reconstruction is quantified using the overlap between injected and recovered waveform, $\mathcal{O}_\text{net}$. The HLV and HLKV network recovers $87\%$ and $86\%$ of the injected waveforms with $\mathcal{O}_\text{net}>0.8$ respectively, compared to $81\%$ with the HL network. The accuracy of BayesWave sky localisation is $\approx 10$ times better for the HLV network than the HL network, as measured by the search area, $\mathcal{A}$, and the sky areas contained within $50\%$ and $90\%$ confidence intervals. Marginal improvement in sky localisation is also observed with the addition of KAGRA. |
2207.14726 | Haida Li | Haida Li, Shengzhi Li, Yongge Ma | Connection Dynamics of Reduced 5-dimensional Kaluza-Klein Theory and Its
Deparametrization | null | null | 10.1103/PhysRevD.107.024047 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | The connection dynamics of the 5-dimensional Kaluza-Klein theory reduced on
4-dimensional spacetime is obtained by performing the Hamiltonian analysis and
canonical transformations. Deparametrization is achieved in the spherically
symmetric model of the theory without introducing additional matter fields
beyond the 5-dimensional gravity. Thus the physical time evolution and the
physical spatial coordinate can be provided by the geometrical degrees of
freedom in the higher dimensional spacetime.
| [
{
"created": "Fri, 29 Jul 2022 14:59:57 GMT",
"version": "v1"
}
] | 2023-02-15 | [
[
"Li",
"Haida",
""
],
[
"Li",
"Shengzhi",
""
],
[
"Ma",
"Yongge",
""
]
] | The connection dynamics of the 5-dimensional Kaluza-Klein theory reduced on 4-dimensional spacetime is obtained by performing the Hamiltonian analysis and canonical transformations. Deparametrization is achieved in the spherically symmetric model of the theory without introducing additional matter fields beyond the 5-dimensional gravity. Thus the physical time evolution and the physical spatial coordinate can be provided by the geometrical degrees of freedom in the higher dimensional spacetime. |
1512.08029 | Emil Nissimov | Eduardo Guendelman, Emil Nissimov, Svetlana Pacheva and Michail
Stoilov | Kruskal-Penrose Formalism for Lightlike Thin-Shell Wormholes | 14 pages, few typos corrected, version to be appear in "Springer
Proceedings in Mathematics and Statistics", vol.191, ed. V. Dobrev, Springer
(2016) | Springer Proceedings in Mathematics and Statistics, vol.191 (2016)
245-259 | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The original formulation of the "Einstein-Rosen bridge" in the classic paper
of Einstein and Rosen (1935) is historically the first example of a static
spherically-symmetric wormhole solution. It is not equivalent to the concept of
the dynamical and non-traversable Schwarzschild wormhole, also called
"Einstein-Rosen bridge" in modern textbooks on general relativity. In previous
papers of ours we have provided a mathematically correct treatment of the
original "Einstein-Rosen bridge" as a traversable wormhole by showing that it
requires the presence of a special kind of "exotic matter" located on the
wormhole throat - a lightlike brane (the latter was overlooked in the original
1935 paper). In the present note we continue our thorough study of the original
"Einstein-Rosen bridge" as a simplest example of a lightlike thin-shell
wormhole by explicitly deriving its description in terms of the Kruskal-Penrose
formalism for maximal analytic extension of the underlying wormhole spacetime
manifold. Further, we generalize the Kruskal-Penrose description to the case of
more complicated lightlike thin-shell wormholes with two throats exhibiting a
remarkable property of QCD-like charge confinement.
| [
{
"created": "Fri, 25 Dec 2015 19:08:53 GMT",
"version": "v1"
},
{
"created": "Sat, 22 Oct 2016 16:44:02 GMT",
"version": "v2"
}
] | 2017-08-01 | [
[
"Guendelman",
"Eduardo",
""
],
[
"Nissimov",
"Emil",
""
],
[
"Pacheva",
"Svetlana",
""
],
[
"Stoilov",
"Michail",
""
]
] | The original formulation of the "Einstein-Rosen bridge" in the classic paper of Einstein and Rosen (1935) is historically the first example of a static spherically-symmetric wormhole solution. It is not equivalent to the concept of the dynamical and non-traversable Schwarzschild wormhole, also called "Einstein-Rosen bridge" in modern textbooks on general relativity. In previous papers of ours we have provided a mathematically correct treatment of the original "Einstein-Rosen bridge" as a traversable wormhole by showing that it requires the presence of a special kind of "exotic matter" located on the wormhole throat - a lightlike brane (the latter was overlooked in the original 1935 paper). In the present note we continue our thorough study of the original "Einstein-Rosen bridge" as a simplest example of a lightlike thin-shell wormhole by explicitly deriving its description in terms of the Kruskal-Penrose formalism for maximal analytic extension of the underlying wormhole spacetime manifold. Further, we generalize the Kruskal-Penrose description to the case of more complicated lightlike thin-shell wormholes with two throats exhibiting a remarkable property of QCD-like charge confinement. |
1805.02504 | Alexandre Gavrilik | A.M. Gavrilik, I.I. Kachurik, M.V. Khelashvili, A.V. Nazarenko | Condensate of $\mu$-Bose gas as a model of dark matter | 17 pages, 2 figures; two refs. corrected, published in Physica A.
arXiv admin note: substantial text overlap with arXiv:1709.05931 | Physica A 506, pp. 835-843 (2018) | 10.1016/j.physa.2018.05.001 | null | gr-qc astro-ph.GA cond-mat.quant-gas hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Though very popular, Bose-Einstein condensate models of dark matter have some
difficulties. Here we propose the so-called $\mu$-Bose gas model ($\mu$-BGM) as
a model of dark matter, able to treat weak points. Within $\mu$-BGM, the
$\mu$-dependence of thermodynamics arises through the respective $\mu$-calculus
(it generalizes usual differential calculus) and enters the partition function,
total number of particles, internal energy, etc. We study thermodynamic
geometry of the $\mu$-BGM and find singular behavior of (scalar) curvature,
confirming Bose-like condensation. The critical temperature of condensation
$T^{(\mu)}_c$ for $\mu\neq 0$ is higher than the boson $T_c$. We find other
important virtues of $\mu$-thermodynamics versus usual bosons and conclude: the
condensate of $\mu$-Bose gas can serve as (an effective) model of
galactic-halos dark matter.
| [
{
"created": "Thu, 3 May 2018 20:01:26 GMT",
"version": "v1"
},
{
"created": "Thu, 31 May 2018 12:31:34 GMT",
"version": "v2"
}
] | 2018-06-04 | [
[
"Gavrilik",
"A. M.",
""
],
[
"Kachurik",
"I. I.",
""
],
[
"Khelashvili",
"M. V.",
""
],
[
"Nazarenko",
"A. V.",
""
]
] | Though very popular, Bose-Einstein condensate models of dark matter have some difficulties. Here we propose the so-called $\mu$-Bose gas model ($\mu$-BGM) as a model of dark matter, able to treat weak points. Within $\mu$-BGM, the $\mu$-dependence of thermodynamics arises through the respective $\mu$-calculus (it generalizes usual differential calculus) and enters the partition function, total number of particles, internal energy, etc. We study thermodynamic geometry of the $\mu$-BGM and find singular behavior of (scalar) curvature, confirming Bose-like condensation. The critical temperature of condensation $T^{(\mu)}_c$ for $\mu\neq 0$ is higher than the boson $T_c$. We find other important virtues of $\mu$-thermodynamics versus usual bosons and conclude: the condensate of $\mu$-Bose gas can serve as (an effective) model of galactic-halos dark matter. |
0805.1998 | Florian Kuhnel | Florian Kuhnel and Dominik J. Schwarz | Stochastic Inflation and Dimensional Reduction | 4 pages, 1 figure; v2: minor changes; v3: revised and extended | Phys.Rev.D78:103501,2008 | 10.1103/PhysRevD.78.103501 | BI-TP 2008/10 | gr-qc astro-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a replica field-theoretic approach to stochastic inflation in
which a manifestation of dimensional reduction is found. The scale above which
the latter dominates grows exponentially fast with time and thus affects
largest super-horizon scales. We find inevitable modifications of the spectral
index on those scales. An explicit relation between the noise correlator and
the non-gaussianity parameter f_NL is found.
| [
{
"created": "Wed, 14 May 2008 13:09:38 GMT",
"version": "v1"
},
{
"created": "Thu, 15 May 2008 19:00:58 GMT",
"version": "v2"
},
{
"created": "Fri, 31 Oct 2008 15:18:02 GMT",
"version": "v3"
}
] | 2008-11-26 | [
[
"Kuhnel",
"Florian",
""
],
[
"Schwarz",
"Dominik J.",
""
]
] | We present a replica field-theoretic approach to stochastic inflation in which a manifestation of dimensional reduction is found. The scale above which the latter dominates grows exponentially fast with time and thus affects largest super-horizon scales. We find inevitable modifications of the spectral index on those scales. An explicit relation between the noise correlator and the non-gaussianity parameter f_NL is found. |
2205.12036 | Joseph Ntahompagaze | Joseph Ntahompagaze and Amare Abebe and Manasse R. Mbonye | Large-scale structure power spectrum from scalar-tensor gravity | Accepted for publication in International Journal of Modern Physics D | null | 10.1142/S0218271822500717 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | This work deals with the computation of the power spectrum of large-scale
structure using the dynamical system approach for a multi-fluid universe in
scalar-tensor theory of gravity. We use the $1+3$ covariant approach to obtain
evolution equations and study the behavior of the matter power spectrum of
perturbation equations. The study is based on the equivalence between $f(R)$
theory of gravity and scalar-tensor theory of gravity. We find that, for
power-law $(R^{n})$ models, with $1<n<1.3$, we have the power spectrum evolving
above general relativistic scale-invariant line. For $n\geq 1.3$, the power
spectrum starts with constant amplitude then it experiences oscillations and
eventually saturates at finite amplitude. Such behavior is consistent with
other observations in the literature. The result supports the ongoing
investigations of the equivalence between $f(R)$ and scalar-tensor theory at
linear order.
| [
{
"created": "Tue, 24 May 2022 12:43:26 GMT",
"version": "v1"
}
] | 2022-08-31 | [
[
"Ntahompagaze",
"Joseph",
""
],
[
"Abebe",
"Amare",
""
],
[
"Mbonye",
"Manasse R.",
""
]
] | This work deals with the computation of the power spectrum of large-scale structure using the dynamical system approach for a multi-fluid universe in scalar-tensor theory of gravity. We use the $1+3$ covariant approach to obtain evolution equations and study the behavior of the matter power spectrum of perturbation equations. The study is based on the equivalence between $f(R)$ theory of gravity and scalar-tensor theory of gravity. We find that, for power-law $(R^{n})$ models, with $1<n<1.3$, we have the power spectrum evolving above general relativistic scale-invariant line. For $n\geq 1.3$, the power spectrum starts with constant amplitude then it experiences oscillations and eventually saturates at finite amplitude. Such behavior is consistent with other observations in the literature. The result supports the ongoing investigations of the equivalence between $f(R)$ and scalar-tensor theory at linear order. |
0912.0802 | Yungui Gong | Jie Liu, Yungui Gong, Ximing Chen | The dynamical behavior of the Extended Holographic Dark Energy with
Hubble Horizon | 12 pages, 7 figures; minor corrections, PRD in press | Phys.Rev.D81:083536,2010 | 10.1103/PhysRevD.81.083536 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The extended holographic dark energy model with the Hubble horizon as the
infrared cutoff avoids the problem of the circular reasoning of the holographic
dark energy model. Unfortunately, it is hit with the no-go theorem. In this
paper, we consider the extended holographic dark energy model with a potential,
$V(\phi)$, for the Brans-Dicke scalar field. With the addition of a potential
for the Brans-Dicke scalar field, the extended holographic dark energy model
using the Hubble horizon as the infrared cutoff is a viable dark energy model,
and the model has the dark energy dominated attractor solution.
| [
{
"created": "Fri, 4 Dec 2009 09:46:07 GMT",
"version": "v1"
},
{
"created": "Tue, 20 Apr 2010 15:12:56 GMT",
"version": "v2"
}
] | 2010-05-12 | [
[
"Liu",
"Jie",
""
],
[
"Gong",
"Yungui",
""
],
[
"Chen",
"Ximing",
""
]
] | The extended holographic dark energy model with the Hubble horizon as the infrared cutoff avoids the problem of the circular reasoning of the holographic dark energy model. Unfortunately, it is hit with the no-go theorem. In this paper, we consider the extended holographic dark energy model with a potential, $V(\phi)$, for the Brans-Dicke scalar field. With the addition of a potential for the Brans-Dicke scalar field, the extended holographic dark energy model using the Hubble horizon as the infrared cutoff is a viable dark energy model, and the model has the dark energy dominated attractor solution. |
gr-qc/0602094 | Mir Faizal | Mir Faizal | Some Aspects of Virtual Black Holes | 11 pages, 0 figures, accepted for publication in JETP | JETP. 114: 400, 2012 | 10.1134/S1063776112020045 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we shall consistently third quantize modified gravity. Then we
shall analyse certain aspects of virtual black holes in this third quantized
modified gravity. We will see how a statistical mechanical origin for the
Bekenstein-Hawking entropy naturally arises in this model. Furthermore, in this
model the area and thus the entropy of a real macroscopic black hole is
quantized. Virtual black holes cause loss of quantum coherence and this gives
an intrinsic entropy to all physical systems which can be used to define a
direction of time and hence provide a solution to the problem of time.
| [
{
"created": "Thu, 23 Feb 2006 14:08:26 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Nov 2011 13:33:53 GMT",
"version": "v2"
}
] | 2015-06-25 | [
[
"Faizal",
"Mir",
""
]
] | In this paper we shall consistently third quantize modified gravity. Then we shall analyse certain aspects of virtual black holes in this third quantized modified gravity. We will see how a statistical mechanical origin for the Bekenstein-Hawking entropy naturally arises in this model. Furthermore, in this model the area and thus the entropy of a real macroscopic black hole is quantized. Virtual black holes cause loss of quantum coherence and this gives an intrinsic entropy to all physical systems which can be used to define a direction of time and hence provide a solution to the problem of time. |
2404.18548 | Yue Wang | Yue Wang, Qing Gao, Shengqing Gao, Yungui Gong | On the duality in constant-roll inflation | 15 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | There is a duality in the observables $n_s$, $r$ and the inflaton potential
between large and small $\eta_H$ for the constant-roll inflation if the
slow-roll parameter $\epsilon_H$ is negligible. In general, the duality between
$\eta_H$ and $\bar{\eta}_H$ does not hold for the background evolution of the
inflation. For some particular solutions for the constant-roll inflation with
$\eta_H$ being a constant, we find that in the small field approximation, the
potential takes the quadratic form and it remains the same when the parameter
$\eta_H$ changes to $\bar{\eta}_H=3-\eta_H$. If the scalar field is small and
the contribution of $\epsilon_H$ is negligible, we find that there exists the
logarithmic duality and the duality between large and small $\eta_H$ for the
primordial curvature perturbation in inflationary models with the quadratic
potential.
| [
{
"created": "Mon, 29 Apr 2024 09:40:40 GMT",
"version": "v1"
}
] | 2024-04-30 | [
[
"Wang",
"Yue",
""
],
[
"Gao",
"Qing",
""
],
[
"Gao",
"Shengqing",
""
],
[
"Gong",
"Yungui",
""
]
] | There is a duality in the observables $n_s$, $r$ and the inflaton potential between large and small $\eta_H$ for the constant-roll inflation if the slow-roll parameter $\epsilon_H$ is negligible. In general, the duality between $\eta_H$ and $\bar{\eta}_H$ does not hold for the background evolution of the inflation. For some particular solutions for the constant-roll inflation with $\eta_H$ being a constant, we find that in the small field approximation, the potential takes the quadratic form and it remains the same when the parameter $\eta_H$ changes to $\bar{\eta}_H=3-\eta_H$. If the scalar field is small and the contribution of $\epsilon_H$ is negligible, we find that there exists the logarithmic duality and the duality between large and small $\eta_H$ for the primordial curvature perturbation in inflationary models with the quadratic potential. |
2006.05045 | Pankaj Sheoran | Eva Hackmann, Hemwati Nandan, and Pankaj Sheoran | Particle collisions near static spherically symmetric black holes | References and extra discussion added | null | 10.1016/j.physletb.2020.135850 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It has been shown by Ba\~{n}ados, Silk and West (BSW) that the center of mass
energy (E_cm) of test particles starting from rest at infinity and colliding
near the horizon of a Schwarzschild black hole is always finite. In this
communication, we extent the BSW scenario and study two particles with
different energies colliding near the horizon of a static spherically symmetric
black hole. Surprisingly, we find that even for the static spherically
symmetric (i.e., Schwarzschild like) black holes it is possible to obtain an
arbitrarily high E cm from the two test particles colliding near the horizon of
a black hole, if one fine-tunes the parameters of geodesic motion.
| [
{
"created": "Tue, 9 Jun 2020 04:45:30 GMT",
"version": "v1"
},
{
"created": "Thu, 9 Jul 2020 06:27:07 GMT",
"version": "v2"
}
] | 2020-10-28 | [
[
"Hackmann",
"Eva",
""
],
[
"Nandan",
"Hemwati",
""
],
[
"Sheoran",
"Pankaj",
""
]
] | It has been shown by Ba\~{n}ados, Silk and West (BSW) that the center of mass energy (E_cm) of test particles starting from rest at infinity and colliding near the horizon of a Schwarzschild black hole is always finite. In this communication, we extent the BSW scenario and study two particles with different energies colliding near the horizon of a static spherically symmetric black hole. Surprisingly, we find that even for the static spherically symmetric (i.e., Schwarzschild like) black holes it is possible to obtain an arbitrarily high E cm from the two test particles colliding near the horizon of a black hole, if one fine-tunes the parameters of geodesic motion. |
0801.0240 | Luca Bombelli | Roman Sverdlov and Luca Bombelli | Gravity and Matter in Causal Set Theory | 13 pages, no figures; In version 2, friendlier results than in
version 1 are obtained following much shorter derivations | Class.Quant.Grav.26:075011,2009 | 10.1088/0264-9381/26/7/075011 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The goal of this paper is to propose an approach to the formulation of
dynamics for causal sets and coupled matter fields. We start from the continuum
version of the action for a Klein-Gordon field coupled to gravity, and rewrite
it first using quantities that have a direct correspondent in the case of a
causal set, namely volumes, causal relations, and timelike lengths, as
variables to describe the geometry. In this step, the local Lagrangian density
$L(f;x)$ for a set of fields $f$ is recast into a quasilocal expression
$L_0(f;p,q)$ that depends on pairs of causally related points $p \prec q$ and
is a function of the values of $f$ in the Alexandrov set defined by those
points, and whose limit as $p$ and $q$ approach a common point $x$ is $L(f;x)$.
We then describe how to discretize $L_0(f;p,q)$, and use it to define a
discrete action.
| [
{
"created": "Mon, 31 Dec 2007 20:52:14 GMT",
"version": "v1"
},
{
"created": "Sun, 13 Jul 2008 20:57:58 GMT",
"version": "v2"
}
] | 2009-03-24 | [
[
"Sverdlov",
"Roman",
""
],
[
"Bombelli",
"Luca",
""
]
] | The goal of this paper is to propose an approach to the formulation of dynamics for causal sets and coupled matter fields. We start from the continuum version of the action for a Klein-Gordon field coupled to gravity, and rewrite it first using quantities that have a direct correspondent in the case of a causal set, namely volumes, causal relations, and timelike lengths, as variables to describe the geometry. In this step, the local Lagrangian density $L(f;x)$ for a set of fields $f$ is recast into a quasilocal expression $L_0(f;p,q)$ that depends on pairs of causally related points $p \prec q$ and is a function of the values of $f$ in the Alexandrov set defined by those points, and whose limit as $p$ and $q$ approach a common point $x$ is $L(f;x)$. We then describe how to discretize $L_0(f;p,q)$, and use it to define a discrete action. |
2005.14241 | Oleg Zaslavskii | O. B. Zaslavskii | Super-Penrose process for extremal rotating neutral white holes | 13 pages. Presentation expanded and improved. To appear in GRG | Gen. Relat. Grav. 52 (2020) 104 | 10.1007/s10714-020-02761-4 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider collision of two particles 1 and 2 near the horizon of the
extremal rotating axially symmetric neutral generic black hole producing
particles 3 and 4. We discuss the scenario in which both particles 3 and 4 fall
into a black hole and move in a white hole region. If particle 1 is fine-tuned,
the energy $E_{c.m.}$ in the centre of mass grows unbounded (the
Ba\~{n}ados-Silk-West effect). Then, particle 3 \ can, in principle, reach a
flat infinity in another universe. If not only $E_{c.m.}$ but also the
corresponding Killing energy $E$ is unbounded, this gives a so-called
super-Penrose process (SPP). We show that the SPP\ is indeed possible. Thus
white holes turn out to be potential sources of high energy fluxes that
transfers from one universe to another. This generalizes recent observaitons
made by Patil and Harada for the Kerr metric. We analyze two different regimes
of the process on different scales.
| [
{
"created": "Thu, 28 May 2020 19:03:49 GMT",
"version": "v1"
},
{
"created": "Mon, 19 Oct 2020 10:38:51 GMT",
"version": "v2"
}
] | 2020-11-11 | [
[
"Zaslavskii",
"O. B.",
""
]
] | We consider collision of two particles 1 and 2 near the horizon of the extremal rotating axially symmetric neutral generic black hole producing particles 3 and 4. We discuss the scenario in which both particles 3 and 4 fall into a black hole and move in a white hole region. If particle 1 is fine-tuned, the energy $E_{c.m.}$ in the centre of mass grows unbounded (the Ba\~{n}ados-Silk-West effect). Then, particle 3 \ can, in principle, reach a flat infinity in another universe. If not only $E_{c.m.}$ but also the corresponding Killing energy $E$ is unbounded, this gives a so-called super-Penrose process (SPP). We show that the SPP\ is indeed possible. Thus white holes turn out to be potential sources of high energy fluxes that transfers from one universe to another. This generalizes recent observaitons made by Patil and Harada for the Kerr metric. We analyze two different regimes of the process on different scales. |
0901.4955 | Bruno Giacomazzo | Luca Baiotti, Bruno Giacomazzo, Luciano Rezzolla | Accurate evolutions of inspiralling neutron-star binaries: assessment of
the truncation error | 13 pages, 5 figures. Minor changes to match published version. Added
figure 5 right panel | Class.Quant.Grav.26:114005,2009 | 10.1088/0264-9381/26/11/114005 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We have recently presented an investigation in full general relativity of the
dynamics and gravitational-wave emission from binary neutron stars which
inspiral and merge, producing a black hole surrounded by a torus (see
arXiv:0804.0594). We here discuss in more detail the convergence properties of
the results presented in arXiv:0804.0594 and, in particular, the deterioration
of the convergence rate at the merger and during the survival of the merged
object, when strong shocks are formed and turbulence develops. We also show
that physically reasonable and numerically convergent results obtained at
low-resolution suffer however from large truncation errors and hence are of
little physical use. We summarize our findings in an "error budget", which
includes the different sources of possible inaccuracies we have investigated
and provides a first quantitative assessment of the precision in the modelling
of compact fluid binaries.
| [
{
"created": "Fri, 30 Jan 2009 19:01:54 GMT",
"version": "v1"
},
{
"created": "Thu, 21 May 2009 10:44:42 GMT",
"version": "v2"
}
] | 2009-06-10 | [
[
"Baiotti",
"Luca",
""
],
[
"Giacomazzo",
"Bruno",
""
],
[
"Rezzolla",
"Luciano",
""
]
] | We have recently presented an investigation in full general relativity of the dynamics and gravitational-wave emission from binary neutron stars which inspiral and merge, producing a black hole surrounded by a torus (see arXiv:0804.0594). We here discuss in more detail the convergence properties of the results presented in arXiv:0804.0594 and, in particular, the deterioration of the convergence rate at the merger and during the survival of the merged object, when strong shocks are formed and turbulence develops. We also show that physically reasonable and numerically convergent results obtained at low-resolution suffer however from large truncation errors and hence are of little physical use. We summarize our findings in an "error budget", which includes the different sources of possible inaccuracies we have investigated and provides a first quantitative assessment of the precision in the modelling of compact fluid binaries. |
1602.08949 | Bayram Tekin | Bayram Tekin | Inflation in pure gravity with only massless spin-2 fields | 5 pages,1 figure, reference added, typos corrected | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that without introducing additional fields or extra degrees of
freedom, a specific higher derivative extension of Einstein's gravity that has
only a massless spin-2 excitation in its perturbative spectrum, has an
inflationary period, a quasi-de Sitter phase with enough number of e-foldings
required to solve the horizon and related problems. The crucial ingredient in
the construction is the curvature dependence of the effective Newton's
constant.
| [
{
"created": "Mon, 29 Feb 2016 13:19:59 GMT",
"version": "v1"
},
{
"created": "Wed, 2 Mar 2016 13:48:13 GMT",
"version": "v2"
}
] | 2016-03-03 | [
[
"Tekin",
"Bayram",
""
]
] | We show that without introducing additional fields or extra degrees of freedom, a specific higher derivative extension of Einstein's gravity that has only a massless spin-2 excitation in its perturbative spectrum, has an inflationary period, a quasi-de Sitter phase with enough number of e-foldings required to solve the horizon and related problems. The crucial ingredient in the construction is the curvature dependence of the effective Newton's constant. |
0907.0824 | Samad Khakshournia | S. Khakshournia | On matching LTB and Vaidya spacetimes through a null hypersurface | 5 pages, to appear in GRG | Gen.Rel.Grav.42:381-385,2010 | 10.1007/s10714-009-0858-y | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work the matching of a LTB interior solution representing dust matter
to the Vaidya exterior solution describing null fluid through a null
hypersurface is studied. Different cases in which one is able to smoothly match
these two solutions to Einstein equations along a null hypesurface are
discussed.
| [
{
"created": "Sun, 5 Jul 2009 05:20:29 GMT",
"version": "v1"
}
] | 2014-11-20 | [
[
"Khakshournia",
"S.",
""
]
] | In this work the matching of a LTB interior solution representing dust matter to the Vaidya exterior solution describing null fluid through a null hypersurface is studied. Different cases in which one is able to smoothly match these two solutions to Einstein equations along a null hypesurface are discussed. |
2204.07983 | Deyou Chen | Chuanhong Gao, Deyou Chen, Chengye Yu, Peng Wang | Chaos bound and its violation in charged Kiselev black hole | 17 pages | Physics Letters B 833 (2022) 137343 | 10.1016/j.physletb.2022.137343 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | The chaos bound in the near-horizon regions has been studied through the
expansions of the metric functions on the horizon. In this paper, we
investigate the chaos bound in the the near-horizon region and at a certain
distance from the horizon of a charged Kiselev black hole. The value of the
Lyapunov exponent is accurately calculated by a Jacobian matrix. The angular
momentum of a charged particle around the black hole affects not only the
exponent, but also the position of the equilibrium orbit. This position
gradually moves away from the horizon with the increase of the angular
momentum. We find that the the bound is violated at a certain distance from the
horizon and there is no violation in the near-horizon region when the charge
mass ratio of the particle is fixed. The small value of the normalization
factor is more likely to cause the violation.
| [
{
"created": "Sun, 17 Apr 2022 11:38:05 GMT",
"version": "v1"
},
{
"created": "Thu, 28 Apr 2022 13:57:50 GMT",
"version": "v2"
}
] | 2022-09-14 | [
[
"Gao",
"Chuanhong",
""
],
[
"Chen",
"Deyou",
""
],
[
"Yu",
"Chengye",
""
],
[
"Wang",
"Peng",
""
]
] | The chaos bound in the near-horizon regions has been studied through the expansions of the metric functions on the horizon. In this paper, we investigate the chaos bound in the the near-horizon region and at a certain distance from the horizon of a charged Kiselev black hole. The value of the Lyapunov exponent is accurately calculated by a Jacobian matrix. The angular momentum of a charged particle around the black hole affects not only the exponent, but also the position of the equilibrium orbit. This position gradually moves away from the horizon with the increase of the angular momentum. We find that the the bound is violated at a certain distance from the horizon and there is no violation in the near-horizon region when the charge mass ratio of the particle is fixed. The small value of the normalization factor is more likely to cause the violation. |
0709.1892 | Edward Anderson | Edward Anderson | Records Theory | 29 pages and 1 figure. References updated and Journal Reference added | Int.J.Mod.Phys.D18:635-667,2009 | 10.1142/S0218271809014686 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In quantum gravity, one seeks to combine quantum mechanics and general
relativity. In such attempts, one comes across the `problem of time' impasse:
the notion of time is conceptually different in each of these theories. In this
paper, I consider the timeless records approach toward resolving this. Records
are localized, information-containing subconfigurations of a single instant.
Records theory is the study of these and of how science (or history) is to be
abstracted from correlations between them. I critically evaluate motivations
for this approach that have previously appeared in the literature. I provide a
ground-level structure for records theory and discuss what kind of further
tools are needed, illustrated with some toy models: ordinary mechanics,
relatonal particle dynamics, detector models and inhomogeneous perturbations
about homogeneous cosmology.
| [
{
"created": "Wed, 12 Sep 2007 14:51:16 GMT",
"version": "v1"
},
{
"created": "Wed, 10 Oct 2007 17:17:58 GMT",
"version": "v2"
},
{
"created": "Fri, 2 Nov 2007 11:43:15 GMT",
"version": "v3"
},
{
"created": "Tue, 20 Nov 2007 18:15:49 GMT",
"version": "v4"
},
{
"cr... | 2009-09-24 | [
[
"Anderson",
"Edward",
""
]
] | In quantum gravity, one seeks to combine quantum mechanics and general relativity. In such attempts, one comes across the `problem of time' impasse: the notion of time is conceptually different in each of these theories. In this paper, I consider the timeless records approach toward resolving this. Records are localized, information-containing subconfigurations of a single instant. Records theory is the study of these and of how science (or history) is to be abstracted from correlations between them. I critically evaluate motivations for this approach that have previously appeared in the literature. I provide a ground-level structure for records theory and discuss what kind of further tools are needed, illustrated with some toy models: ordinary mechanics, relatonal particle dynamics, detector models and inhomogeneous perturbations about homogeneous cosmology. |
1307.5885 | Antonia Zipfel | Thomas Thiemann and Antonia Zipfel | Linking covariant and canonical LQG II: Spin foam projector | 62 pages, 14 figures Abstract changed, slightly reorganized, minor
errors corrected | null | 10.1088/0264-9381/31/12/125008 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In a seminal paper, Kaminski, Kisielowski an Lewandowski for the first time
extended the definition of spin foam models to arbitrary boundary graphs. This
is a prerequisite in order to make contact to the canonical formulation of Loop
Quantum Gravity (LQG) whose Hilbert space contains all these graphs. This makes
it finally possible to investigate the question whether any of the presently
considered spin foam models yields a rigging map for any of the presently
defined Hamiltonian constraint operators.
In the analysis of this would-be spin foam rigging map we are able to
identify an elementary spin foam transfer matrix that allows to generate any
finite foam as a finite power of the transfer matrix. However, it transpires
that the resulting object, as written, does not define a projector on the
physical Hilbert space. This statement is independent of the concrete spin foam
model and Hamiltonian constraint. Nevertehless, the transfer matrix potentially
contains the necessary ingredient in order to construct a proper rigging map in
terms of a modified transfer matrix.
| [
{
"created": "Mon, 22 Jul 2013 20:56:17 GMT",
"version": "v1"
},
{
"created": "Tue, 26 Nov 2013 11:24:38 GMT",
"version": "v2"
}
] | 2015-06-16 | [
[
"Thiemann",
"Thomas",
""
],
[
"Zipfel",
"Antonia",
""
]
] | In a seminal paper, Kaminski, Kisielowski an Lewandowski for the first time extended the definition of spin foam models to arbitrary boundary graphs. This is a prerequisite in order to make contact to the canonical formulation of Loop Quantum Gravity (LQG) whose Hilbert space contains all these graphs. This makes it finally possible to investigate the question whether any of the presently considered spin foam models yields a rigging map for any of the presently defined Hamiltonian constraint operators. In the analysis of this would-be spin foam rigging map we are able to identify an elementary spin foam transfer matrix that allows to generate any finite foam as a finite power of the transfer matrix. However, it transpires that the resulting object, as written, does not define a projector on the physical Hilbert space. This statement is independent of the concrete spin foam model and Hamiltonian constraint. Nevertehless, the transfer matrix potentially contains the necessary ingredient in order to construct a proper rigging map in terms of a modified transfer matrix. |
gr-qc/0604040 | Joseph Henson | Joe Henson | Macroscopic observables and Lorentz violation in discrete quantum
gravity | 15 pages, 1 figure, laTeX | null | null | null | gr-qc | null | This article concerns the fate of local Lorentz invariance in quantum
gravity, particularly for approaches in which a discrete structure replaces
continuum spacetime. Some features of standard quantum mechanics, presented in
a sum-over-histories formulation, are reviewed, and their consequences for such
theories are discussed. It is argued that, if the individual histories of a
theory give bad approximations to macroscopic continuum properties in some
frames, then it is inevitable that the theory violates Lorentz symmetry.
| [
{
"created": "Mon, 10 Apr 2006 10:27:03 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Henson",
"Joe",
""
]
] | This article concerns the fate of local Lorentz invariance in quantum gravity, particularly for approaches in which a discrete structure replaces continuum spacetime. Some features of standard quantum mechanics, presented in a sum-over-histories formulation, are reviewed, and their consequences for such theories are discussed. It is argued that, if the individual histories of a theory give bad approximations to macroscopic continuum properties in some frames, then it is inevitable that the theory violates Lorentz symmetry. |
2207.03995 | Rogerio Teixeira Cavalcanti | Rogerio T. Cavalcanti, Kelvin dos S. Alves and Julio M. Hoff da Silva | Near horizon thermodynamics of hairy black holes from gravitational
decoupling | 11 pages, 8 figures | Universe 8 (2022) 7, 363 | 10.3390/universe8070363 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | The horizon structure and thermodynamics of hairy spherically symmetric black
holes generated by the gravitational decoupling method are carefully
investigated. The temperature and heat capacity of the black hole is
determined, as well as how the hairy parameters affect the thermodynamics. It
allows the analysis of the thermal stability and the possible existence of a
remanent black hole. We also calculate the Hawking radiation corrected by the
generalized uncertainty principle. For such we consider the emission of
fermions and apply the tunneling method to the generalized Dirac equation. It
shows that, despite the horizon location being the same of the Schwarzschild
one for a suitable choice of parameters, the physical phenomena happening near
the horizon of both black holes are qualitatively different.
| [
{
"created": "Thu, 7 Jul 2022 02:53:48 GMT",
"version": "v1"
}
] | 2022-07-11 | [
[
"Cavalcanti",
"Rogerio T.",
""
],
[
"Alves",
"Kelvin dos S.",
""
],
[
"da Silva",
"Julio M. Hoff",
""
]
] | The horizon structure and thermodynamics of hairy spherically symmetric black holes generated by the gravitational decoupling method are carefully investigated. The temperature and heat capacity of the black hole is determined, as well as how the hairy parameters affect the thermodynamics. It allows the analysis of the thermal stability and the possible existence of a remanent black hole. We also calculate the Hawking radiation corrected by the generalized uncertainty principle. For such we consider the emission of fermions and apply the tunneling method to the generalized Dirac equation. It shows that, despite the horizon location being the same of the Schwarzschild one for a suitable choice of parameters, the physical phenomena happening near the horizon of both black holes are qualitatively different. |
0911.3094 | Salvatore Capozziello | Charalampos Bogdanos, Salvatore Capozziello, Mariafelicia De
Laurentis, Savvas Nesseris | Massive, massless and ghost modes of gravitational waves from
higher-order gravity | 11 pages, 3 figures | Astropart.Phys.34:236-244,2010 | 10.1016/j.astropartphys.2010.08.001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We linearize the field equations for higher order theories that contain
scalar invariants other than the Ricci scalar. We find that besides a massless
spin-2 field (the standard graviton), the theory contains also spin-0 and
spin-2 massive modes with the latter being, in general, ghost modes. Then, we
investigate the possible detectability of such additional polarization modes of
a stochastic gravitational wave by ground-based and space interferometric
detectors. Finally, we extend the formalism of the cross-correlation analysis,
including the additional polarization modes, and calculate the detectable
energy density of the spectrum for a stochastic background of the relic gravity
waves that corresponds to our model. For the situation considered here, we find
that these massive modes are certainly of interest for direct detection by the
LISA experiment.
| [
{
"created": "Mon, 16 Nov 2009 17:39:36 GMT",
"version": "v1"
},
{
"created": "Wed, 25 Nov 2009 14:53:37 GMT",
"version": "v2"
},
{
"created": "Tue, 26 Jan 2010 13:42:24 GMT",
"version": "v3"
}
] | 2014-11-20 | [
[
"Bogdanos",
"Charalampos",
""
],
[
"Capozziello",
"Salvatore",
""
],
[
"De Laurentis",
"Mariafelicia",
""
],
[
"Nesseris",
"Savvas",
""
]
] | We linearize the field equations for higher order theories that contain scalar invariants other than the Ricci scalar. We find that besides a massless spin-2 field (the standard graviton), the theory contains also spin-0 and spin-2 massive modes with the latter being, in general, ghost modes. Then, we investigate the possible detectability of such additional polarization modes of a stochastic gravitational wave by ground-based and space interferometric detectors. Finally, we extend the formalism of the cross-correlation analysis, including the additional polarization modes, and calculate the detectable energy density of the spectrum for a stochastic background of the relic gravity waves that corresponds to our model. For the situation considered here, we find that these massive modes are certainly of interest for direct detection by the LISA experiment. |
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