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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
2212.12427 | Jose Beltr\'an Jim\'enez | Katsuki Aoki, Jose Beltr\'an Jim\'enez, David Figueruelo | Some disquisitions on cosmological 2-form dualities | 52 pages. V2 matches published version with improved discussions and
additional appendix | null | 10.1088/1475-7516/2023/04/059 | YITP-22-158 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we study different aspect of self-interacting 2-form fields with
special emphasis in their cosmological applications. We provide the explicit
construction of how massless 2-forms are compatible with the cosmological
principle without resorting to the dual scalar field formulation. In terms of
the 2-form, the residual Euclidean group is non-trivially realised by means of
a combination of external spatial translations and internal gauge
transformations. After presenting the general discussion of the dualities in
cosmological scenarios, we analyse particular examples for some singular models
and discuss in some detail the dual descriptions of the DBI, the cuscuton and
the ghost condensate as well as the role of the duality in the effective field
theories of cosmological perturbations. We then proceed to analysing scenarios
with several self-interacting massless 2-forms and we show that they naturally
provide the dual description of a solid. We then show how the perfect fluid and
superfluids can be obtained by taking the appropriate limits in the dual
formulations. We finally consider the case of massive 2-forms and their duals
and briefly discuss their potential signatures in gravitational waves
astronomy.
| [
{
"created": "Thu, 22 Dec 2022 15:41:51 GMT",
"version": "v1"
},
{
"created": "Mon, 20 Nov 2023 17:39:31 GMT",
"version": "v2"
}
] | 2023-11-21 | [
[
"Aoki",
"Katsuki",
""
],
[
"Jiménez",
"Jose Beltrán",
""
],
[
"Figueruelo",
"David",
""
]
] | In this work we study different aspect of self-interacting 2-form fields with special emphasis in their cosmological applications. We provide the explicit construction of how massless 2-forms are compatible with the cosmological principle without resorting to the dual scalar field formulation. In terms of the 2-form, the residual Euclidean group is non-trivially realised by means of a combination of external spatial translations and internal gauge transformations. After presenting the general discussion of the dualities in cosmological scenarios, we analyse particular examples for some singular models and discuss in some detail the dual descriptions of the DBI, the cuscuton and the ghost condensate as well as the role of the duality in the effective field theories of cosmological perturbations. We then proceed to analysing scenarios with several self-interacting massless 2-forms and we show that they naturally provide the dual description of a solid. We then show how the perfect fluid and superfluids can be obtained by taking the appropriate limits in the dual formulations. We finally consider the case of massive 2-forms and their duals and briefly discuss their potential signatures in gravitational waves astronomy. |
1606.07000 | Lionel Philippoz | H. Rizwana Kausar, Lionel Philippoz, Philippe Jetzer | Gravitational Wave Polarization Modes in $f(R)$ Theories | 7 pages; accepted for publication in Phys. Rev. D | Phys. Rev. D 93, 124071 (2016) | 10.1103/PhysRevD.93.124071 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Many studies have been carried out in the literature to evaluate the number
of polarization modes of gravitational waves in modified theories, in
particular in $f(R)$ theories. In the latter ones, besides the usual two
transverse-traceless tensor modes present in general relativity, there are two
additional scalar ones: a massive longitudinal mode and a massless transverse
mode (the so-called breathing mode). This last mode has often been overlooked
in the literature, due to the assumption that the application of the Lorenz
gauge implies transverse-traceless wave solutions. We however show that this is
in general not possible and, in particular, that the traceless condition cannot
be imposed due to the fact that we no longer have a Minkowski background
metric. Our findings are in agreement with the results found using the
Newman-Penrose formalism, and thus clarify the inconsistencies found so far in
the literature.
| [
{
"created": "Wed, 22 Jun 2016 16:07:12 GMT",
"version": "v1"
}
] | 2018-07-26 | [
[
"Kausar",
"H. Rizwana",
""
],
[
"Philippoz",
"Lionel",
""
],
[
"Jetzer",
"Philippe",
""
]
] | Many studies have been carried out in the literature to evaluate the number of polarization modes of gravitational waves in modified theories, in particular in $f(R)$ theories. In the latter ones, besides the usual two transverse-traceless tensor modes present in general relativity, there are two additional scalar ones: a massive longitudinal mode and a massless transverse mode (the so-called breathing mode). This last mode has often been overlooked in the literature, due to the assumption that the application of the Lorenz gauge implies transverse-traceless wave solutions. We however show that this is in general not possible and, in particular, that the traceless condition cannot be imposed due to the fact that we no longer have a Minkowski background metric. Our findings are in agreement with the results found using the Newman-Penrose formalism, and thus clarify the inconsistencies found so far in the literature. |
gr-qc/0506004 | Eloy Ay\'on-Beato | Eloy Ay\'on-Beato, Cuauhtemoc Campuzano, and Alberto Garc\'ia | Conformally Flat Noncircular Spacetimes | 7 pages | Phys.Rev. D74 (2006) 024014 | 10.1103/PhysRevD.74.024014 | CECS-PHY-05-09 | gr-qc hep-th | null | The general metric for conformally flat stationary cyclic symmetric
noncircular spacetimes is explicitly given. In spite of the complexity
introduced by the inclusion of noncircular contributions, the related metric is
derived via the full integration of the conformal flatness constraints. It is
also shown that the conditions for the existence of a rotation axis
(axisymmetry) are the same ones which restrict the above class of spacetimes to
be static. As a consequence, a known theorem by Collinson is just part of a
more general result: any conformally flat stationary cyclic symmetric
spacetime, even a noncircular one, is additionally axisymmetric if and only if
it is also static. Since recent astrophysical motivations point in the
direction of considering noncircular configurations to describe magnetized
neutron stars, the above results seem to be relevant in this context.
| [
{
"created": "Wed, 1 Jun 2005 04:59:20 GMT",
"version": "v1"
}
] | 2016-08-16 | [
[
"Ayón-Beato",
"Eloy",
""
],
[
"Campuzano",
"Cuauhtemoc",
""
],
[
"García",
"Alberto",
""
]
] | The general metric for conformally flat stationary cyclic symmetric noncircular spacetimes is explicitly given. In spite of the complexity introduced by the inclusion of noncircular contributions, the related metric is derived via the full integration of the conformal flatness constraints. It is also shown that the conditions for the existence of a rotation axis (axisymmetry) are the same ones which restrict the above class of spacetimes to be static. As a consequence, a known theorem by Collinson is just part of a more general result: any conformally flat stationary cyclic symmetric spacetime, even a noncircular one, is additionally axisymmetric if and only if it is also static. Since recent astrophysical motivations point in the direction of considering noncircular configurations to describe magnetized neutron stars, the above results seem to be relevant in this context. |
1607.05661 | Andrea Taracchini | Stanislav Babak, Andrea Taracchini, Alessandra Buonanno | Validating the effective-one-body model of spinning, precessing binary
black holes against numerical relativity | 16 pages, 8 figures | Phys. Rev. D 95, 024010 (2017) | 10.1103/PhysRevD.95.024010 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In Ref. [1], the properties of the first gravitational wave detected by LIGO,
GW150914, were measured by employing an effective-one-body (EOB) model of
precessing binary black holes whose underlying dynamics and waveforms were
calibrated to numerical-relativity (NR) simulations. Here, we perform the first
extensive comparison of such EOBNR model to 70 precessing NR waveforms that
span mass ratios from 1 to 5, dimensionless spin magnitudes up to 0.5, generic
spin orientations, and length of about 20 orbits. We work in the observer's
inertial frame and include all $\ell=2$ modes in the gravitational-wave
polarizations. We introduce new prescriptions for the EOB ringdown signal
concerning its spectrum and time of onset. For total masses between 10Msun and
200Msun, we find that precessing EOBNR waveforms have unfaithfulness within
about 3% to NR waveforms when considering the Advanced-LIGO design noise curve.
This result is obtained without recalibration of the inspiral-plunge of the
underlying nonprecessing EOBNR model. The unfaithfulness is computed with
maximization over time and phase of arrival, sky location and polarization of
the EOBNR waveform and it is averaged over sky location and polarization of the
NR signal. We also present comparisons between NR and EOBNR waveforms in a
frame that tracks the orbital precession.
| [
{
"created": "Tue, 19 Jul 2016 17:08:11 GMT",
"version": "v1"
}
] | 2017-01-11 | [
[
"Babak",
"Stanislav",
""
],
[
"Taracchini",
"Andrea",
""
],
[
"Buonanno",
"Alessandra",
""
]
] | In Ref. [1], the properties of the first gravitational wave detected by LIGO, GW150914, were measured by employing an effective-one-body (EOB) model of precessing binary black holes whose underlying dynamics and waveforms were calibrated to numerical-relativity (NR) simulations. Here, we perform the first extensive comparison of such EOBNR model to 70 precessing NR waveforms that span mass ratios from 1 to 5, dimensionless spin magnitudes up to 0.5, generic spin orientations, and length of about 20 orbits. We work in the observer's inertial frame and include all $\ell=2$ modes in the gravitational-wave polarizations. We introduce new prescriptions for the EOB ringdown signal concerning its spectrum and time of onset. For total masses between 10Msun and 200Msun, we find that precessing EOBNR waveforms have unfaithfulness within about 3% to NR waveforms when considering the Advanced-LIGO design noise curve. This result is obtained without recalibration of the inspiral-plunge of the underlying nonprecessing EOBNR model. The unfaithfulness is computed with maximization over time and phase of arrival, sky location and polarization of the EOBNR waveform and it is averaged over sky location and polarization of the NR signal. We also present comparisons between NR and EOBNR waveforms in a frame that tracks the orbital precession. |
0809.2839 | J. E. Horvath | J.E. Horvath | Dark matter, dark energy and modern cosmology: the case for a Kuhnian
paradigm shift | 16 pp. 2 .ps figures | Cosmos Hist.5:287,2009 | null | null | gr-qc astro-ph physics.hist-ph physics.pop-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Several works in the last few years devoted to measure fundamental probes of
contemporary cosmology have suggested the existence of a delocalized dominant
component (the "dark energy"), in addition to the several-decade-old evidence
for "dark matter" other than ordinary baryons, both assuming the description of
gravity to be correct. Either we are faced to accept the ignorance of at least
95 % of the content of the universe or consider a deep change of the conceptual
framework to understand the data. Thus, the situation seems to be completely
favorable for a Kuhnian paradigm shift in either particle physics or cosmology.
We attempt to offer here a brief discussion of these issues from this
particular perspective, arguing that the situation qualifies as a textbook
Kuhnian anomaly, and offer a tentative identification of some of the actual
elements typically associated with the paradigm shift process "in the works" in
contemporary science.
| [
{
"created": "Wed, 17 Sep 2008 14:12:39 GMT",
"version": "v1"
}
] | 2014-11-18 | [
[
"Horvath",
"J. E.",
""
]
] | Several works in the last few years devoted to measure fundamental probes of contemporary cosmology have suggested the existence of a delocalized dominant component (the "dark energy"), in addition to the several-decade-old evidence for "dark matter" other than ordinary baryons, both assuming the description of gravity to be correct. Either we are faced to accept the ignorance of at least 95 % of the content of the universe or consider a deep change of the conceptual framework to understand the data. Thus, the situation seems to be completely favorable for a Kuhnian paradigm shift in either particle physics or cosmology. We attempt to offer here a brief discussion of these issues from this particular perspective, arguing that the situation qualifies as a textbook Kuhnian anomaly, and offer a tentative identification of some of the actual elements typically associated with the paradigm shift process "in the works" in contemporary science. |
2307.04041 | Tomas Ort\'in | Carmen G\'omez-Fayr\'en, Patrick Meessen and Tom\'as Ort\'in | Covariant generalized conserved charges of General Relativity | References added and some typos corrected. Version to be published in
JHEP | null | null | IFT-UAM/CSIC-23-076 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Motivated by the current research of generalized symmetries and the
construction of conserved charges in pure Einstein gravity linearized over
Minkowski spacetime in Cartesian coordinates, we investigate, from a purely
classical point of view, the construction of these charges in a coordinate- and
frame-independent language in order to generalize them further. We show that
all the charges constructed in that context are associated to the conformal
Killing-Yano 2-forms of Minkowski spacetime. Furthermore, we prove that those
associated to closed conformal Killing-Yano 2-forms are identical to the
charges constructed by Kastor and Traschen for their dual Killing-Yano
(d-2)-forms. We discuss the number of independent and non-trivial gravitational
charges that can be constructed in this way.
| [
{
"created": "Sat, 8 Jul 2023 20:21:44 GMT",
"version": "v1"
},
{
"created": "Fri, 4 Aug 2023 14:29:49 GMT",
"version": "v2"
},
{
"created": "Fri, 15 Sep 2023 09:14:20 GMT",
"version": "v3"
}
] | 2023-09-18 | [
[
"Gómez-Fayrén",
"Carmen",
""
],
[
"Meessen",
"Patrick",
""
],
[
"Ortín",
"Tomás",
""
]
] | Motivated by the current research of generalized symmetries and the construction of conserved charges in pure Einstein gravity linearized over Minkowski spacetime in Cartesian coordinates, we investigate, from a purely classical point of view, the construction of these charges in a coordinate- and frame-independent language in order to generalize them further. We show that all the charges constructed in that context are associated to the conformal Killing-Yano 2-forms of Minkowski spacetime. Furthermore, we prove that those associated to closed conformal Killing-Yano 2-forms are identical to the charges constructed by Kastor and Traschen for their dual Killing-Yano (d-2)-forms. We discuss the number of independent and non-trivial gravitational charges that can be constructed in this way. |
2108.03573 | Sourabh Nampalliwar | Sourabh Nampalliwar | Strong field tests of gravity with electromagnetic and gravitational
waves | Contribution to the 2021 Gravitation session of the 55th Rencontres
de Moriond | null | null | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | For nearly a century, Einstein's theory of gravity has been the standard
theory for describing gravitational phenomena in our universe. Along with its
successes, limitations of the theory from theoretical (e.g., singularities) and
observational (e.g., dark matter/energy) perspectives have appeared. This has
led to proposals that modify or supersede Einstein's theory, and testing these
theories against data, especially in the strong-field regime, has emerged as a
new paradigm in physics in recent years. Along with the completely new avenue
of gravitational waves, new and improved techniques based on electromagnetic
waves are being used to test general relativity (GR) ever more stringently. As
the realm beyond GR is unknown, a popular approach is to look for
theory-agnostic deviations from GR/predictions of GR. Here I describe how I
have used gravitational waves, X-rays, and black hole shadows to put
constraints on some of these theory-agnostic deviations.
| [
{
"created": "Sun, 8 Aug 2021 06:02:44 GMT",
"version": "v1"
}
] | 2021-08-10 | [
[
"Nampalliwar",
"Sourabh",
""
]
] | For nearly a century, Einstein's theory of gravity has been the standard theory for describing gravitational phenomena in our universe. Along with its successes, limitations of the theory from theoretical (e.g., singularities) and observational (e.g., dark matter/energy) perspectives have appeared. This has led to proposals that modify or supersede Einstein's theory, and testing these theories against data, especially in the strong-field regime, has emerged as a new paradigm in physics in recent years. Along with the completely new avenue of gravitational waves, new and improved techniques based on electromagnetic waves are being used to test general relativity (GR) ever more stringently. As the realm beyond GR is unknown, a popular approach is to look for theory-agnostic deviations from GR/predictions of GR. Here I describe how I have used gravitational waves, X-rays, and black hole shadows to put constraints on some of these theory-agnostic deviations. |
0908.3439 | Antonio De Felice | Antonio De Felice, Jean-Marc Gerard, and Teruaki Suyama | Cosmological perturbations of a perfect fluid and noncommutative
variables | 4 pages, uses RevTeX. Title modified, references and comments added. | Phys.Rev.D81:063527,2010 | 10.1103/PhysRevD.81.063527 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We describe the linear cosmological perturbations of a perfect fluid at the
level of an action, providing thus an alternative to the standard approach
based only on the equations of motion. This action is suited not only to
perfect fluids with a barotropic equation of state, but also to those for which
the pressure depends on two thermodynamical variables. By quantizing the system
we find that (1) some perturbation fields exhibit a noncommutativity quite
analogous to the one observed for a charged particle moving in a strong
magnetic field, (2) local curvature and pressure perturbations cannot be
measured simultaneously, (3) ghosts appear if the null energy condition is
violated.
| [
{
"created": "Mon, 24 Aug 2009 15:21:28 GMT",
"version": "v1"
},
{
"created": "Tue, 30 Mar 2010 03:07:03 GMT",
"version": "v2"
}
] | 2010-04-29 | [
[
"De Felice",
"Antonio",
""
],
[
"Gerard",
"Jean-Marc",
""
],
[
"Suyama",
"Teruaki",
""
]
] | We describe the linear cosmological perturbations of a perfect fluid at the level of an action, providing thus an alternative to the standard approach based only on the equations of motion. This action is suited not only to perfect fluids with a barotropic equation of state, but also to those for which the pressure depends on two thermodynamical variables. By quantizing the system we find that (1) some perturbation fields exhibit a noncommutativity quite analogous to the one observed for a charged particle moving in a strong magnetic field, (2) local curvature and pressure perturbations cannot be measured simultaneously, (3) ghosts appear if the null energy condition is violated. |
1708.00204 | Alexander B. Balakin | Alexander B. Balakin | The extended Einstein-Maxwell-aether-axion model: Exact solutions for
axionically controlled pp-wave aether modes | 8 pages, 0 figures. Replaced by the revised version published in
Modern Physics Letters A; Introduction is extended, Remark, additional
explanations and references are added | Modern Physics Letters A, 33 (2018), 1850050 | 10.1142/S0217732318500505 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The extended Einstein-Maxwell-aether-axion model describes internal
interactions inside the system, which contains gravitational, electromagnetic
fields, the dynamic unit vector field describing the velocity of an aether, and
the pseudoscalar field associated with the axionic dark matter. The specific
feature of this model is that the axion field controls the dynamics of the
aether through the guiding functions incorporated into the Jacobson's
constitutive tensor. Depending on the state of the axion field these guiding
functions can control and switch on or switch off the influence of
acceleration, shear, vorticity and expansion of the aether flow on the state of
physical system as a whole. We obtain new exact solutions, which possess the
pp-wave symmetry, and indicate them by the term pp-wave aether modes in
contrast to the pure pp-waves, which can not propagate in this field
conglomerate. These exact solutions describe a specific dynamic state of the
pseudoscalar field, which corresponds to one of the minima of the axion
potential, and switches off the influence of shear and expansion of the aether
flow; the model does not impose restrictions on the Jacobson's coupling
constants and on the axion mass. Properties of these new exact solutions are
discussed.
| [
{
"created": "Tue, 1 Aug 2017 08:47:33 GMT",
"version": "v1"
},
{
"created": "Sat, 17 Mar 2018 11:49:23 GMT",
"version": "v2"
}
] | 2018-03-20 | [
[
"Balakin",
"Alexander B.",
""
]
] | The extended Einstein-Maxwell-aether-axion model describes internal interactions inside the system, which contains gravitational, electromagnetic fields, the dynamic unit vector field describing the velocity of an aether, and the pseudoscalar field associated with the axionic dark matter. The specific feature of this model is that the axion field controls the dynamics of the aether through the guiding functions incorporated into the Jacobson's constitutive tensor. Depending on the state of the axion field these guiding functions can control and switch on or switch off the influence of acceleration, shear, vorticity and expansion of the aether flow on the state of physical system as a whole. We obtain new exact solutions, which possess the pp-wave symmetry, and indicate them by the term pp-wave aether modes in contrast to the pure pp-waves, which can not propagate in this field conglomerate. These exact solutions describe a specific dynamic state of the pseudoscalar field, which corresponds to one of the minima of the axion potential, and switches off the influence of shear and expansion of the aether flow; the model does not impose restrictions on the Jacobson's coupling constants and on the axion mass. Properties of these new exact solutions are discussed. |
gr-qc/9609024 | Hideki Asada | Hideki Asada and Masaru Shibata | Formulation for nonaxisymmetric uniformly rotating equilibrium
configurations in the second post-Newtonian approximation of general
relativity | 25 pages including 3 tables, REVTeX, 1 postscript figure included; to
appear in Physical Review D | Phys.Rev. D54 (1996) 4944-4954 | 10.1103/PhysRevD.54.4944 | null | gr-qc astro-ph | null | We present a formalism to obtain equilibrium configurations of uniformly
rotating fluid in the second post-Newtonian approximation of general
relativity. In our formalism, we need to solve 29 Poisson equations, but their
source terms decrease rapidly enough at the external region of the matter(i.e.,
at worst $O(r^{-4})$). Hence these Poisson equations can be solved accurately
as the boundary value problem using standard numerical methods.This formalism
will be useful to obtain nonaxisymmetric uniformly rotating equilibrium
configurations such as synchronized binary neutron stars just before merging
and the Jacobi ellipsoid.
| [
{
"created": "Tue, 10 Sep 1996 08:14:42 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Asada",
"Hideki",
""
],
[
"Shibata",
"Masaru",
""
]
] | We present a formalism to obtain equilibrium configurations of uniformly rotating fluid in the second post-Newtonian approximation of general relativity. In our formalism, we need to solve 29 Poisson equations, but their source terms decrease rapidly enough at the external region of the matter(i.e., at worst $O(r^{-4})$). Hence these Poisson equations can be solved accurately as the boundary value problem using standard numerical methods.This formalism will be useful to obtain nonaxisymmetric uniformly rotating equilibrium configurations such as synchronized binary neutron stars just before merging and the Jacobi ellipsoid. |
1505.03539 | Hans Arnold Winther | Hans A. Winther and Pedro G. Ferreira | The Vainshtein mechanism beyond the quasi-static approximation | 20 pages, 14 figures | Phys. Rev. D 92, 064005 (2015) | 10.1103/PhysRevD.92.064005 | null | gr-qc astro-ph.CO hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Theories of modified gravity, in both the linear and fully non-linear regime,
are often studied under the assumption that the evolution of the new (often
scalar) degree of freedom present in the theory is quasi-static. This
approximation significantly simplifies the study of the theory, and one often
has good reason to believe that it should hold. Nevertheless it is a crucial
assumption that should be explicitly checked whenever possible. In this paper
we do so for the Vainshtein mechanism. By solving for the full spatial and time
evolution of the Dvali-Gabadadze-Porrati and the Cubic Galileon model, in a
spherical symmetric spacetime, we are able to demonstrate that the Vainshtein
solution is a stable attractor and forms no matter what initial conditions we
take for the scalar field. Furthermore,the quasi-static approximation is also
found to be a very good approximation whenever it exists. For the best-fit
Cubic Galileon model, however, we find that for deep voids at late times, the
numerical solution blows up at the same time as the quasi-static solution
ceases to exist. We argue that this phenomenon is a true instability of the
model.
| [
{
"created": "Wed, 13 May 2015 20:04:40 GMT",
"version": "v1"
}
] | 2015-09-09 | [
[
"Winther",
"Hans A.",
""
],
[
"Ferreira",
"Pedro G.",
""
]
] | Theories of modified gravity, in both the linear and fully non-linear regime, are often studied under the assumption that the evolution of the new (often scalar) degree of freedom present in the theory is quasi-static. This approximation significantly simplifies the study of the theory, and one often has good reason to believe that it should hold. Nevertheless it is a crucial assumption that should be explicitly checked whenever possible. In this paper we do so for the Vainshtein mechanism. By solving for the full spatial and time evolution of the Dvali-Gabadadze-Porrati and the Cubic Galileon model, in a spherical symmetric spacetime, we are able to demonstrate that the Vainshtein solution is a stable attractor and forms no matter what initial conditions we take for the scalar field. Furthermore,the quasi-static approximation is also found to be a very good approximation whenever it exists. For the best-fit Cubic Galileon model, however, we find that for deep voids at late times, the numerical solution blows up at the same time as the quasi-static solution ceases to exist. We argue that this phenomenon is a true instability of the model. |
1605.03632 | Gabriel R. Bengochea | Gabriel Leon, Gabriel R. Bengochea, Susana J. Landau | Quasi-matter bounce and inflation in the light of the CSL model | 27 pages, including 6 figures, 2 tables and one Appendix. Final
version. Accepted in EPJC | Eur. Phys. J. C 76 (2016) 407 | 10.1140/epjc/s10052-016-4245-z | null | gr-qc astro-ph.CO quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Continuous Spontaneous Localization (CSL) model has been proposed as a
possible solution to the quantum measurement problem by modifying the
Schr\"{o}dinger equation. In this work, we apply the CSL model to two
cosmological models of the early Universe: the matter bounce scenario and slow
roll inflation. In particular, we focus on the generation of the classical
primordial inhomogeneities and anisotropies that arise from the dynamical
evolution, provided by the CSL mechanism, of the quantum state associated to
the quantum fields. In each case, we obtained a prediction for the shape and
the parameters characterizing the primordial spectra (scalar and tensor), i.e.
the amplitude, the spectral index and the tensor-to-scalar ratio. We found that
there exist CSL parameter values, allowed by other non-cosmological
experiments, for which our predictions for the angular power spectrum of the
CMB temperature anisotropy are consistent with the best fit canonical model to
the latest data released by the Planck Collaboration.
| [
{
"created": "Wed, 11 May 2016 22:41:31 GMT",
"version": "v1"
},
{
"created": "Tue, 19 Jul 2016 23:41:50 GMT",
"version": "v2"
}
] | 2016-07-21 | [
[
"Leon",
"Gabriel",
""
],
[
"Bengochea",
"Gabriel R.",
""
],
[
"Landau",
"Susana J.",
""
]
] | The Continuous Spontaneous Localization (CSL) model has been proposed as a possible solution to the quantum measurement problem by modifying the Schr\"{o}dinger equation. In this work, we apply the CSL model to two cosmological models of the early Universe: the matter bounce scenario and slow roll inflation. In particular, we focus on the generation of the classical primordial inhomogeneities and anisotropies that arise from the dynamical evolution, provided by the CSL mechanism, of the quantum state associated to the quantum fields. In each case, we obtained a prediction for the shape and the parameters characterizing the primordial spectra (scalar and tensor), i.e. the amplitude, the spectral index and the tensor-to-scalar ratio. We found that there exist CSL parameter values, allowed by other non-cosmological experiments, for which our predictions for the angular power spectrum of the CMB temperature anisotropy are consistent with the best fit canonical model to the latest data released by the Planck Collaboration. |
1003.3328 | Carles Bona | C. Bona and C. Bona-Casas | Constraint-preserving boundary conditions in the 3+1 first-order
approach | Revised version, with conclusive numerical evidence. 23 pages, 12
figures | Phys.Rev.D82:064008,2010 | 10.1103/PhysRevD.82.064008 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A set of energy-momentum constraint-preserving boundary conditions is
proposed for the first-order Z4 case. The stability of a simple numerical
implementation is tested in the linear regime (robust stability test), both
with the standard corner and vertex treatment and with a modified
finite-differences stencil for boundary points which avoids corners and
vertices even in cartesian-like grids. Moreover, the proposed boundary
conditions are tested in a strong field scenario, the Gowdy waves metric,
showing the expected rate of convergence. The accumulated amount of
energy-momentum constraint violations is similar or even smaller than the one
generated by either periodic or reflection conditions, which are exact in the
Gowdy waves case. As a side theoretical result, a new symmetrizer is explicitly
given, which extends the parametric domain of symmetric hyperbolicity for the
Z4 formalism. The application of these results to first-order BSSN-like
formalisms is also considered.
| [
{
"created": "Wed, 17 Mar 2010 09:07:12 GMT",
"version": "v1"
},
{
"created": "Fri, 6 Aug 2010 10:08:30 GMT",
"version": "v2"
}
] | 2014-11-20 | [
[
"Bona",
"C.",
""
],
[
"Bona-Casas",
"C.",
""
]
] | A set of energy-momentum constraint-preserving boundary conditions is proposed for the first-order Z4 case. The stability of a simple numerical implementation is tested in the linear regime (robust stability test), both with the standard corner and vertex treatment and with a modified finite-differences stencil for boundary points which avoids corners and vertices even in cartesian-like grids. Moreover, the proposed boundary conditions are tested in a strong field scenario, the Gowdy waves metric, showing the expected rate of convergence. The accumulated amount of energy-momentum constraint violations is similar or even smaller than the one generated by either periodic or reflection conditions, which are exact in the Gowdy waves case. As a side theoretical result, a new symmetrizer is explicitly given, which extends the parametric domain of symmetric hyperbolicity for the Z4 formalism. The application of these results to first-order BSSN-like formalisms is also considered. |
1302.5884 | Salvatore Capozziello | S. Capozziello, O. Luongo, S. Mancini | Cosmological dark energy effects from entanglement | 5 pages, to be published in Phys. Lett. A | Physics Letters A 377 (2013) 1061-1064 | 10.1016/j.physleta.2013.02.038 | null | gr-qc astro-ph.CO hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The thorny issue of relating information theory to cosmology is here
addressed by assuming a possible connection between quantum entanglement
measures and observable universe. In particular, we propose a cosmological toy
model, where the equation of state of the cosmological fluid, which drives the
today observed cosmic acceleration, can be inferred from quantum entanglement
between different cosmological epochs. In such a way the dynamical dark energy
results as byproduct of quantum entanglement.
| [
{
"created": "Sun, 24 Feb 2013 08:50:52 GMT",
"version": "v1"
}
] | 2013-04-08 | [
[
"Capozziello",
"S.",
""
],
[
"Luongo",
"O.",
""
],
[
"Mancini",
"S.",
""
]
] | The thorny issue of relating information theory to cosmology is here addressed by assuming a possible connection between quantum entanglement measures and observable universe. In particular, we propose a cosmological toy model, where the equation of state of the cosmological fluid, which drives the today observed cosmic acceleration, can be inferred from quantum entanglement between different cosmological epochs. In such a way the dynamical dark energy results as byproduct of quantum entanglement. |
1411.7248 | Victor Fleurov | Y. Vinish and V. Fleurov | Finite width of the sonic event horizon and grey body Hawking radiation | 13 pages, 2 figures | International Journal of Modern Physics B Vol. 30, No. 27 (2016)
1650197 (25 pages) | 10.1142/S0217979216501976 | null | gr-qc physics.optics quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Finite width of the analog event horizon is determined by the nonlinearity
length in the Kerr nonlinear optical system, which is discussed here, or by the
healing length in Bose-Einstein condensates. The various eigen modes of
fluctuations are found in the immediate vicinity of the event horizon and the
scattering matrix due to the finite width horizon is calculated to within the
leading order correction in the nonlinearity length. The Hawking radiation is
found to be that of a grey body with the emissivity larger than one. A
procedure of paraxial quantization of the fluctuation field is discussed and
its connection to the conventional quantization of the electromagnetic field is
demonstrated.
| [
{
"created": "Mon, 24 Nov 2014 13:44:53 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Dec 2014 09:43:24 GMT",
"version": "v2"
},
{
"created": "Fri, 6 Mar 2015 21:46:12 GMT",
"version": "v3"
}
] | 2016-10-20 | [
[
"Vinish",
"Y.",
""
],
[
"Fleurov",
"V.",
""
]
] | Finite width of the analog event horizon is determined by the nonlinearity length in the Kerr nonlinear optical system, which is discussed here, or by the healing length in Bose-Einstein condensates. The various eigen modes of fluctuations are found in the immediate vicinity of the event horizon and the scattering matrix due to the finite width horizon is calculated to within the leading order correction in the nonlinearity length. The Hawking radiation is found to be that of a grey body with the emissivity larger than one. A procedure of paraxial quantization of the fluctuation field is discussed and its connection to the conventional quantization of the electromagnetic field is demonstrated. |
1807.06857 | Swami Vivekanandji Chaurasia | Swami Vivekanandji Chaurasia, Tim Dietrich, Nathan K.
Johnson-McDaniel, Maximiliano Ujevic, Wolfgang Tichy, and Bernd Br\"ugmann | Gravitational waves and mass ejecta from binary neutron star mergers:
Effect of large eccentricities | (26 pages, 17 figures), "CoRe webpage, see
http://www.computational-relativity.org/" | Phys. Rev. D 98, 104005 (2018) | 10.1103/PhysRevD.98.104005 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | As current gravitational wave (GW) detectors increase in sensitivity, and
particularly as new instruments are being planned, there is the possibility
that ground-based GW detectors will observe GWs from highly eccentric neutron
star binaries. We present the first detailed study of highly eccentric BNS
systems with full (3+1)D numerical relativity simulations using consistent
initial conditions, i.e., setups which are in agreement with the Einstein
equations and with the equations of general relativistic hydrodynamics in
equilibrium. Overall, our simulations cover two different equations of state
(EOSs), two different spin configurations, and three to four different initial
eccentricities for each pairing of EOS and spin. We extract from the simulated
waveforms the frequency of the f-mode oscillations induced during close
encounters before the merger of the two stars. The extracted frequency is in
good agreement with f-mode oscillations of individual stars for the
irrotational cases, which allows an independent measure of the supranuclear
equation of state not accessible for binaries on quasi-circular orbits. The
energy stored in these f-mode oscillations can be as large as $10^{-3}M_\odot
\sim 10^{51}$ erg, even with a soft EOS. In order to estimate the stored
energy, we also examine the effects of mode mixing due to the stars' offset
from the origin on the f-mode contribution to the GW signal. While in general
(eccentric) neutron star mergers produce bright electromagnetic counterparts,
we find that the luminosity decreases when the eccentricity becomes too large,
due to a decrease of the ejecta mass. Finally, the use of consistent initial
configurations also allows us to produce high-quality waveforms for different
eccentricities which can be used as a testbed for waveform model development of
highly eccentric binary neutron star systems.
| [
{
"created": "Wed, 18 Jul 2018 10:49:29 GMT",
"version": "v1"
},
{
"created": "Mon, 12 Nov 2018 10:19:58 GMT",
"version": "v2"
}
] | 2018-11-14 | [
[
"Chaurasia",
"Swami Vivekanandji",
""
],
[
"Dietrich",
"Tim",
""
],
[
"Johnson-McDaniel",
"Nathan K.",
""
],
[
"Ujevic",
"Maximiliano",
""
],
[
"Tichy",
"Wolfgang",
""
],
[
"Brügmann",
"Bernd",
""
]
] | As current gravitational wave (GW) detectors increase in sensitivity, and particularly as new instruments are being planned, there is the possibility that ground-based GW detectors will observe GWs from highly eccentric neutron star binaries. We present the first detailed study of highly eccentric BNS systems with full (3+1)D numerical relativity simulations using consistent initial conditions, i.e., setups which are in agreement with the Einstein equations and with the equations of general relativistic hydrodynamics in equilibrium. Overall, our simulations cover two different equations of state (EOSs), two different spin configurations, and three to four different initial eccentricities for each pairing of EOS and spin. We extract from the simulated waveforms the frequency of the f-mode oscillations induced during close encounters before the merger of the two stars. The extracted frequency is in good agreement with f-mode oscillations of individual stars for the irrotational cases, which allows an independent measure of the supranuclear equation of state not accessible for binaries on quasi-circular orbits. The energy stored in these f-mode oscillations can be as large as $10^{-3}M_\odot \sim 10^{51}$ erg, even with a soft EOS. In order to estimate the stored energy, we also examine the effects of mode mixing due to the stars' offset from the origin on the f-mode contribution to the GW signal. While in general (eccentric) neutron star mergers produce bright electromagnetic counterparts, we find that the luminosity decreases when the eccentricity becomes too large, due to a decrease of the ejecta mass. Finally, the use of consistent initial configurations also allows us to produce high-quality waveforms for different eccentricities which can be used as a testbed for waveform model development of highly eccentric binary neutron star systems. |
1610.00922 | Sudan Hansraj | Sudan Hansraj | Generalised spheroidal spacetimes in 5-D
Einstein--Maxwell--Gauss--Bonnet gravity | 6 figures | null | 10.1140/epjc/s10052-017-5124-y | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The field equations for static EGBM gravity are obtained and transformed to
an equivalent form through a coordinate redefinition. A form for one of the
metric potentials that generalises the spheroidal ansatz of Vaidya--Tikekar
superdense stars and additionally prescribing the electric field intensity
yields viable solutions. Some special cases of the general solution are
considered and analogous classes in the Einstein framework are studied. In
particular the Finch--Skea ansatz is examined in detail and found to satisfy
the elementary physical requirements. These include positivity of pressure and
density, the existence of a pressure free hypersurface marking the boundary,
continuity with the exterior metric, a subluminal sound speed as well as the
energy conditions. Moreover, the solution possesses no coordinate
singularities. It is found that the impact of the Gauss--Bonnet term is to
correct undesirable features in the pressure profile and sound speed index when
compared to the equivalent Einstein gravity model. Furthermore graphical
analyses suggest that higher densities are achievable for the same radial
values when compared to the 5--dimensional Einstein case. The case of a
constant gravitational potential, isothermal distribution as well as an
incompressible fluid are studied. All exact solutions derived exhibit an
equation of state explicitly.
| [
{
"created": "Tue, 4 Oct 2016 10:29:45 GMT",
"version": "v1"
},
{
"created": "Mon, 8 May 2017 15:33:31 GMT",
"version": "v2"
},
{
"created": "Tue, 6 Jun 2017 15:06:14 GMT",
"version": "v3"
}
] | 2017-09-13 | [
[
"Hansraj",
"Sudan",
""
]
] | The field equations for static EGBM gravity are obtained and transformed to an equivalent form through a coordinate redefinition. A form for one of the metric potentials that generalises the spheroidal ansatz of Vaidya--Tikekar superdense stars and additionally prescribing the electric field intensity yields viable solutions. Some special cases of the general solution are considered and analogous classes in the Einstein framework are studied. In particular the Finch--Skea ansatz is examined in detail and found to satisfy the elementary physical requirements. These include positivity of pressure and density, the existence of a pressure free hypersurface marking the boundary, continuity with the exterior metric, a subluminal sound speed as well as the energy conditions. Moreover, the solution possesses no coordinate singularities. It is found that the impact of the Gauss--Bonnet term is to correct undesirable features in the pressure profile and sound speed index when compared to the equivalent Einstein gravity model. Furthermore graphical analyses suggest that higher densities are achievable for the same radial values when compared to the 5--dimensional Einstein case. The case of a constant gravitational potential, isothermal distribution as well as an incompressible fluid are studied. All exact solutions derived exhibit an equation of state explicitly. |
1903.04382 | Haopeng Yan | Haopeng Yan | Influence of a plasma on the observational signature of a high-spin Kerr
black hole | 16 pages, 3 figures. Revised in response to referee's comments,
references added. Accepted for publication in PRD | Phys. Rev. D 99, 084050 (2019) | 10.1103/PhysRevD.99.084050 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | To approach a more reliable observational signature of a high-spin Kerr black
hole, one should take into account the effects of its surroundings. To this end
we study in this paper the influence of a surrounding plasma. We consider its
refractive and dispersive effects on photon trajectories and ignore the
gravitational effects of plasma particles as well as the absorption or
scattering processes of photons. With two specific plasma models, we obtain
analytical formulae for the black hole shadow and for the observational
quantities of an orbiting "hot spot" seen by an observer located far away from
the black hole. We find that the plasma has a frequency-dependent dispersive
effect on the size and shape of the black hole shadow and on the image position
and redshift of the hot spot. These results may be tested by the Event Horizon
Telescope in the future.
| [
{
"created": "Mon, 11 Mar 2019 15:45:21 GMT",
"version": "v1"
},
{
"created": "Wed, 10 Apr 2019 15:01:26 GMT",
"version": "v2"
}
] | 2019-05-08 | [
[
"Yan",
"Haopeng",
""
]
] | To approach a more reliable observational signature of a high-spin Kerr black hole, one should take into account the effects of its surroundings. To this end we study in this paper the influence of a surrounding plasma. We consider its refractive and dispersive effects on photon trajectories and ignore the gravitational effects of plasma particles as well as the absorption or scattering processes of photons. With two specific plasma models, we obtain analytical formulae for the black hole shadow and for the observational quantities of an orbiting "hot spot" seen by an observer located far away from the black hole. We find that the plasma has a frequency-dependent dispersive effect on the size and shape of the black hole shadow and on the image position and redshift of the hot spot. These results may be tested by the Event Horizon Telescope in the future. |
0902.4810 | Aurelien Barrau | S. Alexeyev, A. Barrau, K.A. Rannu | Internal structure of a Maxwell-Gauss-Bonnet black hole | 5 pages, 5 figures, published version with minor changes | Phys.Rev.D79:067503,2009 | 10.1103/PhysRevD.79.067503 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The influence of the Maxwell field on a static, asymptotically flat and
spherically-symmetric Gauss-Bonnet black hole is considered. Numerical
computations suggest that if the charge increases beyond a critical value, the
inner determinant singularity is replaced by an inner singular horizon.
| [
{
"created": "Fri, 27 Feb 2009 11:58:40 GMT",
"version": "v1"
},
{
"created": "Mon, 30 Mar 2009 08:38:12 GMT",
"version": "v2"
}
] | 2009-11-13 | [
[
"Alexeyev",
"S.",
""
],
[
"Barrau",
"A.",
""
],
[
"Rannu",
"K. A.",
""
]
] | The influence of the Maxwell field on a static, asymptotically flat and spherically-symmetric Gauss-Bonnet black hole is considered. Numerical computations suggest that if the charge increases beyond a critical value, the inner determinant singularity is replaced by an inner singular horizon. |
2010.06387 | Scott Todd | Scott L. Todd, Giacomo Pantaleoni, Valentina Baccetti, Nicolas C.
Menicucci | Particle scattering in a sonic analogue of special relativity | 23 pages, 7 figures; updated manuscript to reflect published version
(changed title, corrected typos, updated references) | Phys. Rev. D 104, 064035 (2021) | 10.1103/PhysRevD.104.064035 | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate a simple toy model of particle scattering in the flat
spacetime limit of an analogue-gravity model. The analogue-gravity medium is
treated as a scalar field of phonons that obeys the Klein-Gordon equation and
thus admits a Lorentz symmetry with respect to $c_\mathrm{s}$, the speed of
sound in the medium. The particle from which the phonons are scattered is
external to the system and does not obey the sonic Lorentz symmetry that the
phonon field obeys. In-universe observers who use the exchange of sound to
operationally measure distance and duration find that the external particle
appears to be a sonically Lorentz-violating particle. By performing a sonic
analogue to Compton scattering, in-universe observers can determine if they are
in motion with respect to their medium. If in-universe observers were then to
correctly postulate the dispersion relation of the external particle, their
velocity with respect to the medium could be found.
| [
{
"created": "Tue, 13 Oct 2020 13:39:14 GMT",
"version": "v1"
},
{
"created": "Fri, 11 Feb 2022 04:23:15 GMT",
"version": "v2"
}
] | 2022-02-14 | [
[
"Todd",
"Scott L.",
""
],
[
"Pantaleoni",
"Giacomo",
""
],
[
"Baccetti",
"Valentina",
""
],
[
"Menicucci",
"Nicolas C.",
""
]
] | We investigate a simple toy model of particle scattering in the flat spacetime limit of an analogue-gravity model. The analogue-gravity medium is treated as a scalar field of phonons that obeys the Klein-Gordon equation and thus admits a Lorentz symmetry with respect to $c_\mathrm{s}$, the speed of sound in the medium. The particle from which the phonons are scattered is external to the system and does not obey the sonic Lorentz symmetry that the phonon field obeys. In-universe observers who use the exchange of sound to operationally measure distance and duration find that the external particle appears to be a sonically Lorentz-violating particle. By performing a sonic analogue to Compton scattering, in-universe observers can determine if they are in motion with respect to their medium. If in-universe observers were then to correctly postulate the dispersion relation of the external particle, their velocity with respect to the medium could be found. |
2401.01815 | Alex Kirillov | A.A. Kirillov, E.P. Savelova | On properties of the distribution of virtual wormholes in a vacuum | 19 pages, no figures | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | A model of space-time foam in the form of an arbitrary distribution of
spherical Euclidean wormholes is considered. A method for constructing the
exact solution of Einstein's Euclidean equations for the metric corresponding
to this model is proposed. In the framework of our model we obtain the
expression for the Euclidean action and its dependence on the parameters of
wormholes in the explicit form. It is shown how the solutions obtained make it
possible to determine all possible correlation functions associated with the
parameters of virtual wormholes in the vacuum state.
| [
{
"created": "Wed, 3 Jan 2024 16:18:53 GMT",
"version": "v1"
}
] | 2024-01-04 | [
[
"Kirillov",
"A. A.",
""
],
[
"Savelova",
"E. P.",
""
]
] | A model of space-time foam in the form of an arbitrary distribution of spherical Euclidean wormholes is considered. A method for constructing the exact solution of Einstein's Euclidean equations for the metric corresponding to this model is proposed. In the framework of our model we obtain the expression for the Euclidean action and its dependence on the parameters of wormholes in the explicit form. It is shown how the solutions obtained make it possible to determine all possible correlation functions associated with the parameters of virtual wormholes in the vacuum state. |
1001.4195 | Jorma Louko | George T. Kottanattu, Jorma Louko | Topological geon black holes in Einstein-Yang-Mills theory | 27 pages. v3: Presentation expanded. Minor corrections and additions | Commun. Math. Phys. 303 (2011) 127-148 | 10.1007/s00220-011-1195-z | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct topological geon quotients of two families of
Einstein-Yang-Mills black holes. For Kuenzle's static, spherically symmetric
SU(n) black holes with n>2, a geon quotient exists but generically requires
promoting charge conjugation into a gauge symmetry. For Kleihaus and Kunz's
static, axially symmetric SU(2) black holes a geon quotient exists without
gauging charge conjugation, and the parity of the gauge field winding number
determines whether the geon gauge bundle is trivial. The geon's gauge bundle
structure is expected to have an imprint in the Hawking-Unruh effect for
quantum fields that couple to the background gauge field.
| [
{
"created": "Sat, 23 Jan 2010 19:26:03 GMT",
"version": "v1"
},
{
"created": "Sat, 20 Mar 2010 19:55:39 GMT",
"version": "v2"
},
{
"created": "Tue, 15 Mar 2011 15:55:52 GMT",
"version": "v3"
}
] | 2011-03-16 | [
[
"Kottanattu",
"George T.",
""
],
[
"Louko",
"Jorma",
""
]
] | We construct topological geon quotients of two families of Einstein-Yang-Mills black holes. For Kuenzle's static, spherically symmetric SU(n) black holes with n>2, a geon quotient exists but generically requires promoting charge conjugation into a gauge symmetry. For Kleihaus and Kunz's static, axially symmetric SU(2) black holes a geon quotient exists without gauging charge conjugation, and the parity of the gauge field winding number determines whether the geon gauge bundle is trivial. The geon's gauge bundle structure is expected to have an imprint in the Hawking-Unruh effect for quantum fields that couple to the background gauge field. |
gr-qc/0009058 | Raphael Dias Martins De Paola | R.D.M. De Paola and N.F. Svaiter | A Rotating Vacuum and the Quantum Mach's Principle | 18 pages, notations for the Green's functions are corrected only.
ubmitted to Classical and Quantum Gravity | null | null | CBPF-NF-063/00 | gr-qc hep-th | null | In this work we consider a quantum analog of Newton's bucket experiment in a
flat spacetime: we take an Unruh-DeWitt detector in interaction with a real
massless scalar field. We calculate the detector's excitation rate when it is
uniformly rotating around some fixed point and the field is prepared in the
Minkowski vacuum and also when the detector is inertial and the field is in the
Trocheries-Takeno vacuum state. These results are compared and the relations
with a quantum analog of Mach's principle are discussed.
| [
{
"created": "Fri, 15 Sep 2000 18:27:48 GMT",
"version": "v1"
},
{
"created": "Mon, 18 Sep 2000 18:05:28 GMT",
"version": "v2"
},
{
"created": "Thu, 19 Oct 2000 21:19:35 GMT",
"version": "v3"
}
] | 2007-05-23 | [
[
"De Paola",
"R. D. M.",
""
],
[
"Svaiter",
"N. F.",
""
]
] | In this work we consider a quantum analog of Newton's bucket experiment in a flat spacetime: we take an Unruh-DeWitt detector in interaction with a real massless scalar field. We calculate the detector's excitation rate when it is uniformly rotating around some fixed point and the field is prepared in the Minkowski vacuum and also when the detector is inertial and the field is in the Trocheries-Takeno vacuum state. These results are compared and the relations with a quantum analog of Mach's principle are discussed. |
1602.06966 | Maria Laura Pucheu | M. L. Pucheu and F. A. P. Alves-Junior and A. B. Barreto and C. Romero | Cosmological models in Weyl geometrical scalar-tensor theory | 16 pages, 19 figures | Phys. Rev. D 94, 064010 (2016) | 10.1103/PhysRevD.94.064010 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate cosmological models in a recently proposed geometrical theory
of gravity, in which the scalar field appears as part of the space-time
geometry. We extend the previous theory to include a scalar potential in the
action. We solve the vacuum field equations for different choices of the scalar
potential and give a detailed analysis of the solutions. We show that in some
cases a cosmological scenario is found that seems to suggest the appearance of
a geometric phase transition. We build a toy model, in which the accelerated
expansion of the early universe is driven by pure geometry.
| [
{
"created": "Mon, 22 Feb 2016 21:15:25 GMT",
"version": "v1"
},
{
"created": "Tue, 5 Jul 2016 19:23:30 GMT",
"version": "v2"
}
] | 2016-09-14 | [
[
"Pucheu",
"M. L.",
""
],
[
"Alves-Junior",
"F. A. P.",
""
],
[
"Barreto",
"A. B.",
""
],
[
"Romero",
"C.",
""
]
] | We investigate cosmological models in a recently proposed geometrical theory of gravity, in which the scalar field appears as part of the space-time geometry. We extend the previous theory to include a scalar potential in the action. We solve the vacuum field equations for different choices of the scalar potential and give a detailed analysis of the solutions. We show that in some cases a cosmological scenario is found that seems to suggest the appearance of a geometric phase transition. We build a toy model, in which the accelerated expansion of the early universe is driven by pure geometry. |
2107.07777 | Marcello Miranda | Marcello Miranda, Daniele Vernieri, Salvatore Capozziello, Francisco
S. N. Lobo | Effective Actions for Loop Quantum Cosmology in Fourth-Order Gravity | v1: 15 pages; v2: 16 pages. Matches published version in EPJC | Eur. Phys. J. C 81, 975 (2021) | 10.1140/epjc/s10052-021-09767-5 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Loop Quantum Cosmology (LQC) is a theory which renders the Big Bang initial
singularity into a quantum bounce, by means of short range repulsive quantum
effects at the Planck scale. In this work, we are interested in reproducing the
effective Friedmann equation of LQC, by considering a generic $f(R,P,Q)$ theory
of gravity, where $R=g^{\mu\nu}R_{\mu\nu}$ is the Ricci scalar,
$P=R_{\mu\nu}R^{\mu\nu}$, and $Q=R_{\alpha\beta\mu\nu}R^{\alpha\beta\mu\nu}$ is
the Kretschmann scalar. An order reduction technique allows us to work in
$f(R,P,Q)$ theories which are perturbatively close to General Relativity, and
to deduce a modified Friedmann equation in the reduced theory. Requiring that
the modified Friedmann equation mimics the effective Friedmann equation of LQC,
we are able to derive several functional forms of $f(R,P,Q)$. We discuss the
necessary conditions to obtain viable bouncing cosmologies for the proposed
effective actions of $f(R,P,Q)$ theory of gravity.
| [
{
"created": "Fri, 16 Jul 2021 09:05:09 GMT",
"version": "v1"
},
{
"created": "Tue, 23 Nov 2021 16:38:12 GMT",
"version": "v2"
}
] | 2021-11-25 | [
[
"Miranda",
"Marcello",
""
],
[
"Vernieri",
"Daniele",
""
],
[
"Capozziello",
"Salvatore",
""
],
[
"Lobo",
"Francisco S. N.",
""
]
] | Loop Quantum Cosmology (LQC) is a theory which renders the Big Bang initial singularity into a quantum bounce, by means of short range repulsive quantum effects at the Planck scale. In this work, we are interested in reproducing the effective Friedmann equation of LQC, by considering a generic $f(R,P,Q)$ theory of gravity, where $R=g^{\mu\nu}R_{\mu\nu}$ is the Ricci scalar, $P=R_{\mu\nu}R^{\mu\nu}$, and $Q=R_{\alpha\beta\mu\nu}R^{\alpha\beta\mu\nu}$ is the Kretschmann scalar. An order reduction technique allows us to work in $f(R,P,Q)$ theories which are perturbatively close to General Relativity, and to deduce a modified Friedmann equation in the reduced theory. Requiring that the modified Friedmann equation mimics the effective Friedmann equation of LQC, we are able to derive several functional forms of $f(R,P,Q)$. We discuss the necessary conditions to obtain viable bouncing cosmologies for the proposed effective actions of $f(R,P,Q)$ theory of gravity. |
gr-qc/0106037 | Hans-Juergen Schmidt | H.-J. Schmidt | The Newtonian limit of fourth-order gravity | 5 pages, LaTeX | Astron.Nachr. 307 (1986) 339 | null | Report UNIPO-MATH-01-Jun-07 | gr-qc | null | The weak-field slow-motion limit of fourth-order gravity will be discussed.
| [
{
"created": "Mon, 11 Jun 2001 14:35:13 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Schmidt",
"H. -J.",
""
]
] | The weak-field slow-motion limit of fourth-order gravity will be discussed. |
0910.3784 | Valentin Kuzmichev | V. E. Kuzmichev, V. V. Kuzmichev (Bogolyubov Institute for Theoretical
Physics) | Universe on Extremely Small Spacetime Scales: Quantum Geometrodynamical
Approach | 18 pages, 4 EPS figure | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The semi-classical approach to the quantum geometrodynamical model is used
for the description of the properties of the universe on extremely small
spacetime scales. Quantum theory for a homogeneous, isotropic and closed
universe is constructed on the basis of a Hamiltonian formalism with the use of
material reference system as a dynamical system defined by macroscopic
relativistic matter. The equations of the model are reduced to the form of the
Einstein-type equations in which the matter energy density has two components
of quantum nature, which behave as antigravitating fluids. The first component
does not vanish in the limit h -> 0 and can be associated with dark energy. The
second component is described by extremely rigid equation of state and goes to
zero after the transition to large spacetime scales. On small spacetime scales
this quantum correction determines the geometry of the universe. This geometry
is conformal to a unit four-sphere embedded in a five-dimensional Euclidean
flat space. When reaching the post-Planck era, the geometry of the universe
changes into the geometry conformal to a unit four-hyperboloid in a
five-dimensional Lorentz-signatured flat space. Near the boundary between two
regions the universe undergoes almost an exponential expansion which passes
smoothly into the expansion under the action of radiation dominating over
matter which is described by the standard cosmological model.
| [
{
"created": "Tue, 20 Oct 2009 09:34:04 GMT",
"version": "v1"
}
] | 2009-10-21 | [
[
"Kuzmichev",
"V. E.",
"",
"Bogolyubov Institute for Theoretical\n Physics"
],
[
"Kuzmichev",
"V. V.",
"",
"Bogolyubov Institute for Theoretical\n Physics"
]
] | The semi-classical approach to the quantum geometrodynamical model is used for the description of the properties of the universe on extremely small spacetime scales. Quantum theory for a homogeneous, isotropic and closed universe is constructed on the basis of a Hamiltonian formalism with the use of material reference system as a dynamical system defined by macroscopic relativistic matter. The equations of the model are reduced to the form of the Einstein-type equations in which the matter energy density has two components of quantum nature, which behave as antigravitating fluids. The first component does not vanish in the limit h -> 0 and can be associated with dark energy. The second component is described by extremely rigid equation of state and goes to zero after the transition to large spacetime scales. On small spacetime scales this quantum correction determines the geometry of the universe. This geometry is conformal to a unit four-sphere embedded in a five-dimensional Euclidean flat space. When reaching the post-Planck era, the geometry of the universe changes into the geometry conformal to a unit four-hyperboloid in a five-dimensional Lorentz-signatured flat space. Near the boundary between two regions the universe undergoes almost an exponential expansion which passes smoothly into the expansion under the action of radiation dominating over matter which is described by the standard cosmological model. |
gr-qc/9910033 | Bernard F. Schutz | Bernard F Schutz | Getting Ready for GEO600 Data | 17 pages, 7 figures, proceedings of Yukawa International Seminar 1999 | Prog.Theor.Phys.Suppl.136:168-182,1999 | 10.1143/PTPS.136.168 | AEI-1999-26 | gr-qc | null | Data of good quality is expected from a number of gravitational wave
detectors within the next two years. One of these, GEO600, has special
capabilities, such as narrow-band operation. I describe here the preparations
that are currently being made for the analysis of GEO600 data.
| [
{
"created": "Sun, 10 Oct 1999 17:33:51 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Schutz",
"Bernard F",
""
]
] | Data of good quality is expected from a number of gravitational wave detectors within the next two years. One of these, GEO600, has special capabilities, such as narrow-band operation. I describe here the preparations that are currently being made for the analysis of GEO600 data. |
0808.3729 | Arunava Bhadra Dr. | A. Bhadra and K. K. Nandi | Gravitational time advancement and its possible detection | 5 pages, 4 figures, a part of the work has been changed in the
revised version | Gen. Rel, Grav. 42 (2010) 293- 302 | 10.1007/s10714-009-0842-6 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The gravitational time advancement is a natural but a consequence of curve
space-time geometry. In the present work the expressions of gravitational time
advancement have been obtained for geodesic motions. The situation when the
distance of signal travel is small in comparison to the distance of closest
approach has also been considered. The possibility of experimental detection of
time advancement effect has been explored.
| [
{
"created": "Wed, 27 Aug 2008 16:00:53 GMT",
"version": "v1"
},
{
"created": "Fri, 5 Dec 2008 15:18:52 GMT",
"version": "v2"
}
] | 2010-02-03 | [
[
"Bhadra",
"A.",
""
],
[
"Nandi",
"K. K.",
""
]
] | The gravitational time advancement is a natural but a consequence of curve space-time geometry. In the present work the expressions of gravitational time advancement have been obtained for geodesic motions. The situation when the distance of signal travel is small in comparison to the distance of closest approach has also been considered. The possibility of experimental detection of time advancement effect has been explored. |
2302.00254 | Chen-Hsu Chien | Chen-Hsu Chien, Gansukh Tumurtushaa, and Dong-han Yeom | Wheeler-DeWitt equation beyond the cosmological horizon: Annihilation to
nothing, infinity avoidance, and loss of quantum coherence | 10 pages, 7 figures, and comments welcome | null | 10.1103/PhysRevD.108.023530 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the Schwarzschild-(anti) de Sitter spacetime with the
anisotropic metric ansatz. The Wheeler-DeWitt equation for such a metric is
solved numerically. In the presence of the cosmological constant $\Lambda$, we
show that two classical wave packets can be annihilated inside the black hole
horizon, i.e., the annihilation-to-nothing scenario. It is interesting that the
Wheeler-DeWitt equation can be extended to the asymptotic de Sitter spacetime
outside the cosmological horizon. Surprisingly, the only bounded nontrivial
wave function beyond the cosmological horizon satisfies the DeWitt boundary
condition, i.e., the wave function must vanish at a certain finite radius. This
might be an alternative explanation to the classicalization of quantum
fluctuations in the de Sitter space, where this topic is also related to
decoherence.
| [
{
"created": "Wed, 1 Feb 2023 05:30:55 GMT",
"version": "v1"
},
{
"created": "Tue, 1 Aug 2023 11:11:04 GMT",
"version": "v2"
}
] | 2023-08-09 | [
[
"Chien",
"Chen-Hsu",
""
],
[
"Tumurtushaa",
"Gansukh",
""
],
[
"Yeom",
"Dong-han",
""
]
] | We investigate the Schwarzschild-(anti) de Sitter spacetime with the anisotropic metric ansatz. The Wheeler-DeWitt equation for such a metric is solved numerically. In the presence of the cosmological constant $\Lambda$, we show that two classical wave packets can be annihilated inside the black hole horizon, i.e., the annihilation-to-nothing scenario. It is interesting that the Wheeler-DeWitt equation can be extended to the asymptotic de Sitter spacetime outside the cosmological horizon. Surprisingly, the only bounded nontrivial wave function beyond the cosmological horizon satisfies the DeWitt boundary condition, i.e., the wave function must vanish at a certain finite radius. This might be an alternative explanation to the classicalization of quantum fluctuations in the de Sitter space, where this topic is also related to decoherence. |
2003.08778 | Naveena Kumara A | Kartheek Hegde, A. Naveena Kumara, C.L. Ahmed Rizwan, Ajith K.M., Md
Sabir Ali | Thermodynamics, Phase Transition and Joule Thomson Expansion of novel
4-D Gauss Bonnet AdS Black Hole | 11 pages, 9 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the thermodynamic behaviour of the four dimension Gauss Bonnet
black hole, proposed in [Phys. Rev. Lett. 124, 081301 (2020)], in the AdS
background . We study the thermodynamics in extended phase space, where the
cosmological constant is taken as the thermodynamic pressure. The black hole
exhibits a phase transition similar to that of van der Waals system. The phase
transition is investigated via isotherms in $P-V$ diagram, Gibbs free energy
and specific heat plots. The charged and neutral cases are considered
separately to observe the effect of charge on critical behaviour. In both cases
the van der Waals like behaviour is exhibited. We also study the throttling
process of the black hole analytically using isenthalpic and inversion curves.
| [
{
"created": "Thu, 19 Mar 2020 13:43:46 GMT",
"version": "v1"
}
] | 2020-03-20 | [
[
"Hegde",
"Kartheek",
""
],
[
"Kumara",
"A. Naveena",
""
],
[
"Rizwan",
"C. L. Ahmed",
""
],
[
"M.",
"Ajith K.",
""
],
[
"Ali",
"Md Sabir",
""
]
] | We investigate the thermodynamic behaviour of the four dimension Gauss Bonnet black hole, proposed in [Phys. Rev. Lett. 124, 081301 (2020)], in the AdS background . We study the thermodynamics in extended phase space, where the cosmological constant is taken as the thermodynamic pressure. The black hole exhibits a phase transition similar to that of van der Waals system. The phase transition is investigated via isotherms in $P-V$ diagram, Gibbs free energy and specific heat plots. The charged and neutral cases are considered separately to observe the effect of charge on critical behaviour. In both cases the van der Waals like behaviour is exhibited. We also study the throttling process of the black hole analytically using isenthalpic and inversion curves. |
2111.02178 | Adam Bauer | Adam Bauer and Alejandro C\'ardenas-Avenda\~no and Charles F. Gammie
and Nicol\'as Yunes | Spherical accretion in alternative theories of gravity | 15 pages, 7 figures | The Astrophysical Journal, 925:119, 2022 | 10.3847/1538-4357/ac3a03 | null | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | The groundbreaking image of the black hole at the center of the M87 galaxy
has raised questions at the intersection of observational astronomy and black
hole physics. How well can the radius of a black hole shadow can be measured,
and can this measurement be used to distinguish general relativity from other
theories of gravity? We explore these questions using a simple spherical flow
model in general relativity, scalar Gauss--Bonnet gravity, and the Rezzolla and
Zhidenko parameterized metric. We assume an optically thin plasma with
power-law emissivity in radius. Along the way we present a generalized Bondi
flow as well as a piecewise-analytic model for the brightness profile of a cold
inflow. We use the second moment of a synthetic image as a proxy for EHT
observables and compute the ratio of the second moment to the radius of the
black hole shadow. We show that corrections to this ratio from modifications to
general relativity are subdominant compared to corrections to the critical
impact parameter, and argue that this is generally true. We find that
astrophysical model parameters are the dominant source of uncertainty in this
calculation, emphasizing the importance of understanding the astrophysical
model. Given a sufficiently accurate astrophysical model, however, it is
possible using measurements of the black hole shadow to distinguish between
general relativity and other theories of gravity.
| [
{
"created": "Wed, 3 Nov 2021 12:38:53 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Nov 2021 12:45:04 GMT",
"version": "v2"
},
{
"created": "Mon, 15 Nov 2021 23:07:28 GMT",
"version": "v3"
}
] | 2022-02-02 | [
[
"Bauer",
"Adam",
""
],
[
"Cárdenas-Avendaño",
"Alejandro",
""
],
[
"Gammie",
"Charles F.",
""
],
[
"Yunes",
"Nicolás",
""
]
] | The groundbreaking image of the black hole at the center of the M87 galaxy has raised questions at the intersection of observational astronomy and black hole physics. How well can the radius of a black hole shadow can be measured, and can this measurement be used to distinguish general relativity from other theories of gravity? We explore these questions using a simple spherical flow model in general relativity, scalar Gauss--Bonnet gravity, and the Rezzolla and Zhidenko parameterized metric. We assume an optically thin plasma with power-law emissivity in radius. Along the way we present a generalized Bondi flow as well as a piecewise-analytic model for the brightness profile of a cold inflow. We use the second moment of a synthetic image as a proxy for EHT observables and compute the ratio of the second moment to the radius of the black hole shadow. We show that corrections to this ratio from modifications to general relativity are subdominant compared to corrections to the critical impact parameter, and argue that this is generally true. We find that astrophysical model parameters are the dominant source of uncertainty in this calculation, emphasizing the importance of understanding the astrophysical model. Given a sufficiently accurate astrophysical model, however, it is possible using measurements of the black hole shadow to distinguish between general relativity and other theories of gravity. |
2010.11823 | Samoil Bilenky M. | S. M. Bilenky | Basics of General Theory of Relativity for Beginners | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a basics of the Einstein General Theory of Relativity. In the
first part of this review we derive relations of Riemann geometry which are
used in the General Relativity. In the second part we discuss Einstein
Equations and some of its consequences (The Schwarzschild solution,
gravitational waves, Friedman Equations etc). In the Appendix we briefly
discuss a history of the discovery of the Einstein Equations.
| [
{
"created": "Thu, 15 Oct 2020 19:54:06 GMT",
"version": "v1"
}
] | 2020-10-23 | [
[
"Bilenky",
"S. M.",
""
]
] | We present a basics of the Einstein General Theory of Relativity. In the first part of this review we derive relations of Riemann geometry which are used in the General Relativity. In the second part we discuss Einstein Equations and some of its consequences (The Schwarzschild solution, gravitational waves, Friedman Equations etc). In the Appendix we briefly discuss a history of the discovery of the Einstein Equations. |
1809.05108 | Laura Bernard | Lorenzo Annulli, Laura Bernard, Diego Blas and Vitor Cardoso | Scattering of scalar, electromagnetic and gravitational waves from
binary systems | 19 pages, 3 figures, to appear in PRD | null | 10.1103/PhysRevD.98.084001 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The direct detection of gravitational waves crowns decades of efforts in the
modelling of sources and of increasing detectors' sensitivity. With future
third-generation Earth-based detectors or space-based observatories,
gravitational-wave astronomy will be at its full bloom. Previously
brushed-aside questions on environmental or other systematic effects in the
generation and propagation of gravitational waves are now begging for a
systematic treatment. Here, we study how electromagnetic and gravitational
radiation is scattered by a binary system. Scattering cross-sections,
resonances and the effect of an impinging wave on a gravitational-bound binary
are worked out for the first time. The ratio between the scattered-wave
amplitude and the incident wave can be of order $10^{-5}$ for known pulsars,
bringing this into the realm of future gravitational-wave observatories. For
currently realistic distribution of compact-object binaries, the interaction
cross-section is too small to be of relevance.
| [
{
"created": "Thu, 13 Sep 2018 18:00:12 GMT",
"version": "v1"
}
] | 2018-10-17 | [
[
"Annulli",
"Lorenzo",
""
],
[
"Bernard",
"Laura",
""
],
[
"Blas",
"Diego",
""
],
[
"Cardoso",
"Vitor",
""
]
] | The direct detection of gravitational waves crowns decades of efforts in the modelling of sources and of increasing detectors' sensitivity. With future third-generation Earth-based detectors or space-based observatories, gravitational-wave astronomy will be at its full bloom. Previously brushed-aside questions on environmental or other systematic effects in the generation and propagation of gravitational waves are now begging for a systematic treatment. Here, we study how electromagnetic and gravitational radiation is scattered by a binary system. Scattering cross-sections, resonances and the effect of an impinging wave on a gravitational-bound binary are worked out for the first time. The ratio between the scattered-wave amplitude and the incident wave can be of order $10^{-5}$ for known pulsars, bringing this into the realm of future gravitational-wave observatories. For currently realistic distribution of compact-object binaries, the interaction cross-section is too small to be of relevance. |
1904.01455 | Upala Mukhopadhyay | Upala Mukhopadhyay, Debasish Majumdar | Swampland Criteria in the Slotheon Field Dark Energy | 15 pages LaTeX, 5 figures | Phys. Rev. D 100, 024006 (2019) | 10.1103/PhysRevD.100.024006 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We explore in this work whether Slotheon model of Dark Energy obeys the
Swampland criteria of string theory. Since de Sitter vacuum is very difficult
to construct in string theory the cosmological constant as an explanation of
Dark Energy is almost ruled out in string theory since it involves a scalar
potential $V$ with positive local minimum that ends up to a stable (or meta
stable) de Sitter (ds) vacuum. In quintessence model however if the derivative
of the scalar potential $V$ ($\nabla V$) is small and $\frac{|\nabla V|}{V}
\sim {\cal {O}}(1)$ then in this situation the potential $V$ can be positive
but the scalar field may not be at the minimum. For a consistent quantum theory
of gravity the theory should not have any ds or meta stable ds vacua. In this
regard the Swampland criterion is proposed which any low energy theory should
obey to be consistent with quantum theory of gravity. This criterion is written
as $|\nabla V|/V > c \sim {\cal {O}}(1)$. In this work we consider a scalar
field model for Dark Energy namely the Slotheon Dark Energy model inspired by
the theories of extra dimensions and show that this Dark Energy model agrees
better with the Swampland criteria than the quintessence Dark Energy model.
| [
{
"created": "Tue, 2 Apr 2019 14:22:04 GMT",
"version": "v1"
},
{
"created": "Fri, 2 Aug 2019 10:41:50 GMT",
"version": "v2"
}
] | 2019-08-05 | [
[
"Mukhopadhyay",
"Upala",
""
],
[
"Majumdar",
"Debasish",
""
]
] | We explore in this work whether Slotheon model of Dark Energy obeys the Swampland criteria of string theory. Since de Sitter vacuum is very difficult to construct in string theory the cosmological constant as an explanation of Dark Energy is almost ruled out in string theory since it involves a scalar potential $V$ with positive local minimum that ends up to a stable (or meta stable) de Sitter (ds) vacuum. In quintessence model however if the derivative of the scalar potential $V$ ($\nabla V$) is small and $\frac{|\nabla V|}{V} \sim {\cal {O}}(1)$ then in this situation the potential $V$ can be positive but the scalar field may not be at the minimum. For a consistent quantum theory of gravity the theory should not have any ds or meta stable ds vacua. In this regard the Swampland criterion is proposed which any low energy theory should obey to be consistent with quantum theory of gravity. This criterion is written as $|\nabla V|/V > c \sim {\cal {O}}(1)$. In this work we consider a scalar field model for Dark Energy namely the Slotheon Dark Energy model inspired by the theories of extra dimensions and show that this Dark Energy model agrees better with the Swampland criteria than the quintessence Dark Energy model. |
2004.03233 | Yuri Pavlov | A. A. Grib, Yu. V. Pavlov | Particles with negative energies in nonrelativistic and relativistic
cases | 10 pages | Symmetry 12 (2020) 528 | 10.3390/sym12040528 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | States of particles with negative energies are considered for the
nonrelativistic and relativistic cases. In nonrelativistic case it is shown
that the decays close to the attracting center can lead to the situation
similar to the Penrose effect for rotating black hole when the energy of one of
the fragments is larger than the energy of the initial body. This is known as
the Oberth effect in the theory of the rocket movement. The realizations of the
Penrose effect in the non-relativistic case in collisions near the attracting
body and in the evaporation of stars from star clusters are indicated. In
relativistic case similar to the well known Penrose process in the ergosphere
of the rotating black hole it is shown that the same situation as in ergosphere
of the black hole occurs in rotating coordinate system in Minkowski space-time
out of the static limit due to existence of negative energies. In relativistic
cases differently from the nonrelativistic ones the mass of the fragment can be
larger than the mass of the decaying body. Negative energies for particles are
possible in relativistic case in cosmology of the expanding space when the
coordinate system is used with nondiagonal term in metrical tensor of the
space-time. Friedmann metrics for three cases: open, close and quasieuclidian,
are analyzed. The De Sitter space-time is shortly discussed.
| [
{
"created": "Tue, 7 Apr 2020 09:56:15 GMT",
"version": "v1"
}
] | 2020-04-08 | [
[
"Grib",
"A. A.",
""
],
[
"Pavlov",
"Yu. V.",
""
]
] | States of particles with negative energies are considered for the nonrelativistic and relativistic cases. In nonrelativistic case it is shown that the decays close to the attracting center can lead to the situation similar to the Penrose effect for rotating black hole when the energy of one of the fragments is larger than the energy of the initial body. This is known as the Oberth effect in the theory of the rocket movement. The realizations of the Penrose effect in the non-relativistic case in collisions near the attracting body and in the evaporation of stars from star clusters are indicated. In relativistic case similar to the well known Penrose process in the ergosphere of the rotating black hole it is shown that the same situation as in ergosphere of the black hole occurs in rotating coordinate system in Minkowski space-time out of the static limit due to existence of negative energies. In relativistic cases differently from the nonrelativistic ones the mass of the fragment can be larger than the mass of the decaying body. Negative energies for particles are possible in relativistic case in cosmology of the expanding space when the coordinate system is used with nondiagonal term in metrical tensor of the space-time. Friedmann metrics for three cases: open, close and quasieuclidian, are analyzed. The De Sitter space-time is shortly discussed. |
1501.05394 | Fan Zhang | Fan Zhang and Sean T. McWilliams and Harald P. Pfeiffer | Stability of exact force-free electrodynamic solutions and scattering
from spacetime curvature | 33 pages, 21 figures; V2 updated to match published version | Phys. Rev. D 92, 024049 (2015) | 10.1103/PhysRevD.92.024049 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, a family of exact force-free electrodynamic (FFE) solutions was
given by Brennan, Gralla and Jacobson, which generalizes earlier solutions by
Michel, Menon and Dermer, and other authors. These solutions have been proposed
as useful models for describing the outer magnetosphere of conducting stars. As
with any exact analytical solution that aspires to describe actual physical
systems, it is vitally important that the solution possess the necessary
stability. In this paper, we show via fully nonlinear numerical simulations
that the aforementioned FFE solutions, despite being highly special in their
properties, are nonetheless stable under small perturbations. Through this
study, we also introduce a three-dimensional pseudospectral relativistic FFE
code that achieves exponential convergence for smooth test cases, as well as
two additional well-posed FFE evolution systems in the appendix that have
desirable mathematical properties. Furthermore, we provide an explicit analysis
that demonstrates how propagation along degenerate principal null directions of
the spacetime curvature tensor simplifies scattering, thereby providing an
intuitive understanding of why these exact solutions are tractable, i.e. why
they are not backscattered by spacetime curvature.
| [
{
"created": "Thu, 22 Jan 2015 05:10:19 GMT",
"version": "v1"
},
{
"created": "Fri, 31 Jul 2015 04:21:32 GMT",
"version": "v2"
}
] | 2015-08-03 | [
[
"Zhang",
"Fan",
""
],
[
"McWilliams",
"Sean T.",
""
],
[
"Pfeiffer",
"Harald P.",
""
]
] | Recently, a family of exact force-free electrodynamic (FFE) solutions was given by Brennan, Gralla and Jacobson, which generalizes earlier solutions by Michel, Menon and Dermer, and other authors. These solutions have been proposed as useful models for describing the outer magnetosphere of conducting stars. As with any exact analytical solution that aspires to describe actual physical systems, it is vitally important that the solution possess the necessary stability. In this paper, we show via fully nonlinear numerical simulations that the aforementioned FFE solutions, despite being highly special in their properties, are nonetheless stable under small perturbations. Through this study, we also introduce a three-dimensional pseudospectral relativistic FFE code that achieves exponential convergence for smooth test cases, as well as two additional well-posed FFE evolution systems in the appendix that have desirable mathematical properties. Furthermore, we provide an explicit analysis that demonstrates how propagation along degenerate principal null directions of the spacetime curvature tensor simplifies scattering, thereby providing an intuitive understanding of why these exact solutions are tractable, i.e. why they are not backscattered by spacetime curvature. |
1504.07657 | Vladimir Ivashchuk | M.E. Abishev, K.A. Boshkayev, V.D. Dzhunushaliev and V.D. Ivashchuk | Dilatonic dyon black hole solutions | 20 pages, 2 figures, 2 tables, Latex. Revised version: 6 refs., 3
remarks, a paragraph in Conclusion and several sentences or phrases are
added; in Sect. 5 numerics are replaced to the end | null | null | IGC-PFUR-15-04-03r | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Dilatonic black hole dyon solutions with arbitrary dilatonic coupling
constant $\lambda \neq 0$ and canonical sign $\varepsilon = +1$ for scalar
field kynetic term are considered. These solutions are defined up to solutions
of two master equations for moduli funtions. For $\lambda^2 \neq 1/2$ the
solutions are extended to $\varepsilon = \pm 1$, where $\varepsilon = -1$
corresponds to ghost (phantom) scalar field. Some physical parameters of the
solutions: gravitational mass, scalar charge, Hawking temperature, black hole
area entropy and parametrized post-Newtonian (PPN) parameters $\beta$ and
$\gamma$ are obtained. It is shown that PPN parameters do not depend on scalar
field coupling $\lambda$ and $\varepsilon$. Two group of bounds on
gravitational mass and scalar charge (for fixed and arbitrary extremality
parameter $\mu >0$) are found by using a certain conjecture on parameters of
solutions when $1 +2 \lambda^2 \varepsilon > 0$. These bounds are verified
numerically for certain examples. By product we are led to well-known lower
bound on mass which was obtained earlier by Gibbons, Kastor, London, Townsend
and Traschen by using spinor techniques.
| [
{
"created": "Tue, 28 Apr 2015 20:58:39 GMT",
"version": "v1"
},
{
"created": "Fri, 12 Jun 2015 19:53:54 GMT",
"version": "v2"
}
] | 2015-06-15 | [
[
"Abishev",
"M. E.",
""
],
[
"Boshkayev",
"K. A.",
""
],
[
"Dzhunushaliev",
"V. D.",
""
],
[
"Ivashchuk",
"V. D.",
""
]
] | Dilatonic black hole dyon solutions with arbitrary dilatonic coupling constant $\lambda \neq 0$ and canonical sign $\varepsilon = +1$ for scalar field kynetic term are considered. These solutions are defined up to solutions of two master equations for moduli funtions. For $\lambda^2 \neq 1/2$ the solutions are extended to $\varepsilon = \pm 1$, where $\varepsilon = -1$ corresponds to ghost (phantom) scalar field. Some physical parameters of the solutions: gravitational mass, scalar charge, Hawking temperature, black hole area entropy and parametrized post-Newtonian (PPN) parameters $\beta$ and $\gamma$ are obtained. It is shown that PPN parameters do not depend on scalar field coupling $\lambda$ and $\varepsilon$. Two group of bounds on gravitational mass and scalar charge (for fixed and arbitrary extremality parameter $\mu >0$) are found by using a certain conjecture on parameters of solutions when $1 +2 \lambda^2 \varepsilon > 0$. These bounds are verified numerically for certain examples. By product we are led to well-known lower bound on mass which was obtained earlier by Gibbons, Kastor, London, Townsend and Traschen by using spinor techniques. |
2011.03036 | Rebecca Ewing | Becca Ewing, Surabhi Sachdev, Ssohrab Borhanian, B.S. Sathyaprakash | Archival searches for stellar-mass binary black holes in LISA | 12 pages, 7 figures | Phys. Rev. D 103, 023025 (2021) | 10.1103/PhysRevD.103.023025 | null | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | Stellar-mass binary black holes will sweep through the frequency band of the
Laser Interferometer Space Antenna (LISA) for months to years before appearing
in the audio-band of ground-based gravitational-wave detectors. One can expect
several tens of these events up to a distance of $500 \,\mathrm{Mpc}$ each
year. The LISA signal-to-noise ratio for such sources even at these close
distances will be too small for a blind search to confidently detect them.
However, next generation ground-based gravitational-wave detectors, expected to
be operational at the time of LISA, will observe them with signal-to-noise
ratios of several thousands and measure their parameters very accurately. We
show that such high fidelity observations of these sources by ground-based
detectors help in archival searches to dig tens of signals out of LISA data
each year.
| [
{
"created": "Thu, 5 Nov 2020 18:49:57 GMT",
"version": "v1"
}
] | 2021-02-03 | [
[
"Ewing",
"Becca",
""
],
[
"Sachdev",
"Surabhi",
""
],
[
"Borhanian",
"Ssohrab",
""
],
[
"Sathyaprakash",
"B. S.",
""
]
] | Stellar-mass binary black holes will sweep through the frequency band of the Laser Interferometer Space Antenna (LISA) for months to years before appearing in the audio-band of ground-based gravitational-wave detectors. One can expect several tens of these events up to a distance of $500 \,\mathrm{Mpc}$ each year. The LISA signal-to-noise ratio for such sources even at these close distances will be too small for a blind search to confidently detect them. However, next generation ground-based gravitational-wave detectors, expected to be operational at the time of LISA, will observe them with signal-to-noise ratios of several thousands and measure their parameters very accurately. We show that such high fidelity observations of these sources by ground-based detectors help in archival searches to dig tens of signals out of LISA data each year. |
2006.01642 | Z. Yousaf | Z. Yousaf | Definition of Complexity Factor for Self-Gravitating Systems in Palatini
$f(R)$ Gravity | 20 pages, 0 figures, version published in Physica Scripta | Phys. Scr. 95, 075307 (2020) | 10.1088/1402-4896/ab9479 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The aim of this paper is to explore the complexity factor (CF) for those
self-gravitating relativistic spheres whose evolution proceeds non-dynamically.
We are adopting the definition of CF mentioned in \cite{PhysRevD.97.044010},
modifying it to the static spherically symmetric case, within the framework of
a modified gravity theory (the Palatini $f(R)$ theory). In this respect, we
have considered radial dependent anisotropic matter content coupled with
spherical geometry and determined the complexity factor involved in the
patterns of radial evolution. We shall explore the field and a well-known
Tolman-Oppenheimer-Volkoff equations. After introducing structure scalars from
the orthogonal decomposition of the Riemann tensor, we shall calculate
complexity factor. An exact analytical model is presented by considering
firstly ansatz provided by Gokhroo and Mehra. The role of matter variables and
$f(R)$ terms are analyzed in the structure formation as well as their evolution
through a complexity factor.
| [
{
"created": "Sat, 30 May 2020 13:32:59 GMT",
"version": "v1"
}
] | 2020-06-03 | [
[
"Yousaf",
"Z.",
""
]
] | The aim of this paper is to explore the complexity factor (CF) for those self-gravitating relativistic spheres whose evolution proceeds non-dynamically. We are adopting the definition of CF mentioned in \cite{PhysRevD.97.044010}, modifying it to the static spherically symmetric case, within the framework of a modified gravity theory (the Palatini $f(R)$ theory). In this respect, we have considered radial dependent anisotropic matter content coupled with spherical geometry and determined the complexity factor involved in the patterns of radial evolution. We shall explore the field and a well-known Tolman-Oppenheimer-Volkoff equations. After introducing structure scalars from the orthogonal decomposition of the Riemann tensor, we shall calculate complexity factor. An exact analytical model is presented by considering firstly ansatz provided by Gokhroo and Mehra. The role of matter variables and $f(R)$ terms are analyzed in the structure formation as well as their evolution through a complexity factor. |
gr-qc/9901026 | Rong Gen Cai | Rong-Gen Cai | Critical behavior in black hole thermodynamics | Revtex, 5 pages, talk given at 5th Italian-Korean Symposium on
Relativistic Astrophysics, Seoul and Suanbo, Korea, 1-7 Sept.1997 | J.Korean Phys.Soc.33:s477-S482,1998 | null | null | gr-qc | null | In this talk I introduce the critical behavior occurring at the extremal
limit of black holes. The extremal limit of black holes is a critical point and
a phase transition takes place from the extremal black holes to their
nonextremal counterparts. Some critical exponents satisfying the scaling laws
are obtained. From the scaling laws we introduce the concept of the effective
dimension of black holes and discuss the relationship between the critical
behavior and the statistical interpretation of black hole entropy.
| [
{
"created": "Sat, 9 Jan 1999 06:44:08 GMT",
"version": "v1"
}
] | 2011-07-19 | [
[
"Cai",
"Rong-Gen",
""
]
] | In this talk I introduce the critical behavior occurring at the extremal limit of black holes. The extremal limit of black holes is a critical point and a phase transition takes place from the extremal black holes to their nonextremal counterparts. Some critical exponents satisfying the scaling laws are obtained. From the scaling laws we introduce the concept of the effective dimension of black holes and discuss the relationship between the critical behavior and the statistical interpretation of black hole entropy. |
2303.15094 | Garrett Gould | Garrett Gould | Higher Order Corrections to Antisymmetric Spherical Solutions in $f(R)$
gravity | 12 pages, 4 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The static, spherical solutions that exhibit an antisymmetry between the
temporal and radial coordinates in $f(R)$ gravity theories are presented. I
present the constraint for this antisymmetry and show that pure $R^2$ models
produce these solutions. An asymptotic expansion approach is taken to find the
solutions, presenting first and second order corrections to the Schwarzschild
metric. The null geodesics and photon sphere are determined for these
corrections. Furthermore, I show that electromagnetic fields produce this
antisymmetry as well. The metric solutions are analyzed in the context of black
holes, bringing forward potentially a new class of black holes in modified
gravity theories.
| [
{
"created": "Mon, 27 Mar 2023 11:01:47 GMT",
"version": "v1"
}
] | 2023-03-28 | [
[
"Gould",
"Garrett",
""
]
] | The static, spherical solutions that exhibit an antisymmetry between the temporal and radial coordinates in $f(R)$ gravity theories are presented. I present the constraint for this antisymmetry and show that pure $R^2$ models produce these solutions. An asymptotic expansion approach is taken to find the solutions, presenting first and second order corrections to the Schwarzschild metric. The null geodesics and photon sphere are determined for these corrections. Furthermore, I show that electromagnetic fields produce this antisymmetry as well. The metric solutions are analyzed in the context of black holes, bringing forward potentially a new class of black holes in modified gravity theories. |
1902.05130 | Enrico Barausse | Olivier Sarbach, Enrico Barausse and Jorge A. Preciado-L\'opez | Well-posed Cauchy formulation for Einstein-\ae ther theory | 20 pages, no figures. Minor changes to match version accepted for
publication in CQG | Class. Quantum Grav. 36 165007 (2019) | 10.1088/1361-6382/ab2e13 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the well-posedness of the initial value (Cauchy) problem of vacuum
Einstein-aether theory. The latter is a Lorentz-violating gravitational theory
consisting of General Relativity with a dynamical timelike 'aether' vector
field, which selects a 'preferred time' direction at each spacetime event. The
Einstein-aether action is quadratic in the aether, and thus yields second order
field equations for the metric and the aether. However, the well-posedness of
the Cauchy problem is not easy to prove away from the simple case of
perturbations over flat space. This is particularly problematic because
well-posedness is a necessary requirement to ensure stability of numerical
evolutions of the initial value problem. Here, we employ a first-order
formulation of Einstein-aether theory in terms of projections on a tetrad
frame. We show that under suitable conditions on the coupling constants of the
theory, the resulting evolution equations can be cast into strongly or even
symmetric hyperbolic form, and therefore they define a well-posed Cauchy
problem.
| [
{
"created": "Wed, 13 Feb 2019 21:03:46 GMT",
"version": "v1"
},
{
"created": "Thu, 27 Jun 2019 07:46:01 GMT",
"version": "v2"
}
] | 2019-08-08 | [
[
"Sarbach",
"Olivier",
""
],
[
"Barausse",
"Enrico",
""
],
[
"Preciado-López",
"Jorge A.",
""
]
] | We study the well-posedness of the initial value (Cauchy) problem of vacuum Einstein-aether theory. The latter is a Lorentz-violating gravitational theory consisting of General Relativity with a dynamical timelike 'aether' vector field, which selects a 'preferred time' direction at each spacetime event. The Einstein-aether action is quadratic in the aether, and thus yields second order field equations for the metric and the aether. However, the well-posedness of the Cauchy problem is not easy to prove away from the simple case of perturbations over flat space. This is particularly problematic because well-posedness is a necessary requirement to ensure stability of numerical evolutions of the initial value problem. Here, we employ a first-order formulation of Einstein-aether theory in terms of projections on a tetrad frame. We show that under suitable conditions on the coupling constants of the theory, the resulting evolution equations can be cast into strongly or even symmetric hyperbolic form, and therefore they define a well-posed Cauchy problem. |
0812.4020 | Jorge Rocha | Jorge V. Rocha | Analytic Approaches to the Study of Small Scale Structure on Cosmic
String Networks | 119 pages, 14 figures, Ph.D. thesis (advisor: Joseph G. Polchinski) | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present an analytic model specifically designed to address the long
standing issue of small scale structure on cosmic string networks. The model is
derived from the microscopic string equations, together with a few motivated
assumptions. The resulting form of the correlation between two points on a
string is exploited to study smoothing by gravitational radiation, loop
formation and lensing by cosmic strings. In addition, the properties of the
small loop population and the possibility of detecting gravitational waves
generated by their lowest harmonics are investigated. Whenever possible, we
compare the predictions of the model to the most recent numerical simulations
of cosmic string networks.
| [
{
"created": "Sat, 20 Dec 2008 01:23:59 GMT",
"version": "v1"
}
] | 2008-12-23 | [
[
"Rocha",
"Jorge V.",
""
]
] | We present an analytic model specifically designed to address the long standing issue of small scale structure on cosmic string networks. The model is derived from the microscopic string equations, together with a few motivated assumptions. The resulting form of the correlation between two points on a string is exploited to study smoothing by gravitational radiation, loop formation and lensing by cosmic strings. In addition, the properties of the small loop population and the possibility of detecting gravitational waves generated by their lowest harmonics are investigated. Whenever possible, we compare the predictions of the model to the most recent numerical simulations of cosmic string networks. |
gr-qc/9610017 | Herbert Balasin | H.Balasin | Colombeau's Generalized Functions on Arbitrary Manifolds | 10 pages, latex2e, amstex macros, no figures | null | null | Alberta-Thy-35-96, TUW96-20 | gr-qc | null | We extend the Colombeau algebra of generalized functions to arbitrary
(infinitely differentiable, paracompact) n-dimensional manifolds M. Embedding
of continuous functions and distributions is achieved with the help of a family
of n-forms defined on the tangent bundle TM, which form a partition of unity
upon integration over the fibres.
| [
{
"created": "Thu, 10 Oct 1996 21:48:25 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Balasin",
"H.",
""
]
] | We extend the Colombeau algebra of generalized functions to arbitrary (infinitely differentiable, paracompact) n-dimensional manifolds M. Embedding of continuous functions and distributions is achieved with the help of a family of n-forms defined on the tangent bundle TM, which form a partition of unity upon integration over the fibres. |
1305.7075 | Fabrizio De Marchi | Massimo Bassan, Fabrizio De Marchi, Lorenzo Marconi, Giuseppe Pucacco,
Ruggero Stanga, Massimo Visco | Torsion pendulum revisited | 17 pages, 4 figures | Physics Letters A Volume 377 (25) Elsevier 2013 | 10.1016/j.physleta.2013.04.017 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present an analysis of the motion of a simple torsion pendulum and we
describe how, with straightforward extensions to the usual basic dynamical
model, we succeed in explaining some unexpected features we found in our data,
like the modulation of the torsion mode at a higher frequency and the frequency
splitting of the swinging motion. Comparison with observed values yields
estimates for the misalignment angles and other parameters of the model.
| [
{
"created": "Thu, 30 May 2013 12:25:24 GMT",
"version": "v1"
}
] | 2013-05-31 | [
[
"Bassan",
"Massimo",
""
],
[
"De Marchi",
"Fabrizio",
""
],
[
"Marconi",
"Lorenzo",
""
],
[
"Pucacco",
"Giuseppe",
""
],
[
"Stanga",
"Ruggero",
""
],
[
"Visco",
"Massimo",
""
]
] | We present an analysis of the motion of a simple torsion pendulum and we describe how, with straightforward extensions to the usual basic dynamical model, we succeed in explaining some unexpected features we found in our data, like the modulation of the torsion mode at a higher frequency and the frequency splitting of the swinging motion. Comparison with observed values yields estimates for the misalignment angles and other parameters of the model. |
2104.11913 | Malcolm MacCallum | M. A. H. MacCallum | Spacetimes with continuous linear isotropies II: boosts | Title amended. This is the 'author's accepted manuscript'. To appear
in General Relativity and Gravitation. In press. Paper I also in press. Paper
III will follow | null | 10.1007/s10714-021-02827-x | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Conditions are found which ensure that local boost invariance (LBI),
invariance under a linear boost isotropy, implies local boost symmetry (LBS),
i.e. the existence of a local group of motions such that for every point $P$ in
a neighbourhood there is a boost leaving $P$ fixed. It is shown that for Petrov
type D spacetimes this requires LBI of the Riemann tensor and its first
derivative. That is also true for most conformally flat spacetimes, but those
with Ricci tensors of Segre type [1(11,1)] may require LBI of the first three
derivatives of curvature to ensure LBS.
| [
{
"created": "Sat, 24 Apr 2021 09:05:41 GMT",
"version": "v1"
},
{
"created": "Tue, 1 Jun 2021 20:44:16 GMT",
"version": "v2"
}
] | 2021-07-21 | [
[
"MacCallum",
"M. A. H.",
""
]
] | Conditions are found which ensure that local boost invariance (LBI), invariance under a linear boost isotropy, implies local boost symmetry (LBS), i.e. the existence of a local group of motions such that for every point $P$ in a neighbourhood there is a boost leaving $P$ fixed. It is shown that for Petrov type D spacetimes this requires LBI of the Riemann tensor and its first derivative. That is also true for most conformally flat spacetimes, but those with Ricci tensors of Segre type [1(11,1)] may require LBI of the first three derivatives of curvature to ensure LBS. |
gr-qc/9305013 | null | Klaus Kirsten and Jaume Garriga | Massless Minimally Coupled Fields in De Sitter Space: O(4)-Symmetric
States Versus De Sitter Invariant Vacuum | TUTP-92-1, to appear in Phys. Rev. D | Phys.Rev. D48 (1993) 567-577 | 10.1103/PhysRevD.48.567 | null | gr-qc hep-th | null | The issue of de Sitter invariance for a massless minimally coupled scalar
field is revisited. Formally, it is possible to construct a de Sitter invariant
state for this case provided that the zero mode of the field is quantized
properly. Here we take the point of view that this state is physically
acceptable, in the sense that physical observables can be computed and have a
reasonable interpretation. In particular, we use this vacuum to derive a new
result: that the squared difference between the field at two points along a
geodesic observer's space-time path grows linearly with the observer's proper
time for a quantum state that does not break de Sitter invariance. Also, we use
the Hadamard formalism to compute the renormalized expectation value of the
energy momentum tensor, both in the O(4) invariant states introduced by Allen
and Follaci, and in the de Sitter invariant vacuum. We find that the vacuum
energy density in the O(4) invariant case is larger than in the de Sitter
invariant case.
| [
{
"created": "Sun, 16 May 1993 17:22:00 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Kirsten",
"Klaus",
""
],
[
"Garriga",
"Jaume",
""
]
] | The issue of de Sitter invariance for a massless minimally coupled scalar field is revisited. Formally, it is possible to construct a de Sitter invariant state for this case provided that the zero mode of the field is quantized properly. Here we take the point of view that this state is physically acceptable, in the sense that physical observables can be computed and have a reasonable interpretation. In particular, we use this vacuum to derive a new result: that the squared difference between the field at two points along a geodesic observer's space-time path grows linearly with the observer's proper time for a quantum state that does not break de Sitter invariance. Also, we use the Hadamard formalism to compute the renormalized expectation value of the energy momentum tensor, both in the O(4) invariant states introduced by Allen and Follaci, and in the de Sitter invariant vacuum. We find that the vacuum energy density in the O(4) invariant case is larger than in the de Sitter invariant case. |
2101.02713 | Davide Poletti | Davide Poletti | Measuring the primordial gravitational wave background in the presence
of other stochastic signals | 23 pages, 8 figures. Accepted on JCAP | null | 10.1088/1475-7516/2021/05/052 | null | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | Standard methodologies for the extraction of the stochastic gravitational
wave background (SGWB) from auto- or cross-correlation of interferometric
signals often involve the use of a filter function. The standard optimal filter
maximizes the signal-to-noise ratio (SNR) between the total SGWB and the noise.
We derive expressions for the optimal filter and SNR in the presence of a
target SGWB plus other unwanted components. We also generalize the methodology
to the case of template-free reconstruction. The formalism allows to easily
perform analyses and forecasts that marginalize over foreground signals, such
as the typical $\Omega_{\rm GW} \propto f^{2/3}$ background arising from binary
coalescence. We demonstrate the methodology with the LISA mission and discuss
possible extensions and domains of application.
| [
{
"created": "Thu, 7 Jan 2021 19:00:02 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Jun 2021 16:35:01 GMT",
"version": "v2"
}
] | 2021-06-16 | [
[
"Poletti",
"Davide",
""
]
] | Standard methodologies for the extraction of the stochastic gravitational wave background (SGWB) from auto- or cross-correlation of interferometric signals often involve the use of a filter function. The standard optimal filter maximizes the signal-to-noise ratio (SNR) between the total SGWB and the noise. We derive expressions for the optimal filter and SNR in the presence of a target SGWB plus other unwanted components. We also generalize the methodology to the case of template-free reconstruction. The formalism allows to easily perform analyses and forecasts that marginalize over foreground signals, such as the typical $\Omega_{\rm GW} \propto f^{2/3}$ background arising from binary coalescence. We demonstrate the methodology with the LISA mission and discuss possible extensions and domains of application. |
2405.09968 | Morgan Le Delliou | Alan Maciel, Morgan Le Delliou, Jos\'e P. Mimoso | New insights on null and timelike warped symmetric spacetime splittings | 27pp | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We explore in detail the 2+2 and 1+1+2 formalism in spherically symmetric
spacetimes, spanning from deducing the dynamical equations to relating them to
the well-known generalised Painlev\'e-Gullstrand (GPG) coordinate system. The
evolution equations are the Raychaudhuri equations for null rays, including
those also known as cross-focusing equations whose derivation, to the best of
our knowledge, we present for the first time. We physically interpret the
scalars that arise in this scenario, namely the flow 2-expansion $\Theta_{n}$,
the flow acceleration $\mathcal{A}$, and the radial extrinsic curvature
$\mathcal{B}$. We derive a coordinate independent formula for the redshift
which shows that $\mathcal{B}$ is the sole source for the redshift in
spherically symmetric spacetimes. We also establish the correspondence between
the 1+1+2 scalars and the 1+3 splitting scalars, expansion and shear. We
further make a comparison with the Newman-Penrose formalism, in order to
clarify the context where each formalism is more useful, and finally, we extend
our results to planar and hyperbolic symmetric warped spacetimes as well, in
particular, the relationship between $\mathcal{B}$ and the redshift.
| [
{
"created": "Thu, 16 May 2024 10:30:18 GMT",
"version": "v1"
}
] | 2024-05-17 | [
[
"Maciel",
"Alan",
""
],
[
"Delliou",
"Morgan Le",
""
],
[
"Mimoso",
"José P.",
""
]
] | We explore in detail the 2+2 and 1+1+2 formalism in spherically symmetric spacetimes, spanning from deducing the dynamical equations to relating them to the well-known generalised Painlev\'e-Gullstrand (GPG) coordinate system. The evolution equations are the Raychaudhuri equations for null rays, including those also known as cross-focusing equations whose derivation, to the best of our knowledge, we present for the first time. We physically interpret the scalars that arise in this scenario, namely the flow 2-expansion $\Theta_{n}$, the flow acceleration $\mathcal{A}$, and the radial extrinsic curvature $\mathcal{B}$. We derive a coordinate independent formula for the redshift which shows that $\mathcal{B}$ is the sole source for the redshift in spherically symmetric spacetimes. We also establish the correspondence between the 1+1+2 scalars and the 1+3 splitting scalars, expansion and shear. We further make a comparison with the Newman-Penrose formalism, in order to clarify the context where each formalism is more useful, and finally, we extend our results to planar and hyperbolic symmetric warped spacetimes as well, in particular, the relationship between $\mathcal{B}$ and the redshift. |
1606.04932 | Parampreet Singh | Sahil Saini, Parampreet Singh | Geodesic completeness and the lack of strong singularities in effective
loop quantum Kantowski-Sachs spacetime | Revised version. Discussion in the proof on absence of strong
singularities expanded. References added. To appear in CQG | Class. Quantum Grav. 33 245019 (2016) | 10.1088/0264-9381/33/24/245019 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Resolution of singularities in the Kantowski-Sachs model due to
non-perturbative quantum gravity effects is investigated. Using the effective
spacetime description for the improved dynamics version of loop quantum
Kantowski-Sachs spacetimes, we show that even though expansion and shear
scalars are universally bounded, there can exist events where curvature
invariants can diverge. However, such events can occur only for very exotic
equations of state when pressure or derivatives of energy density with respect
to triads become infinite at a finite energy density. In all other cases
curvature invariants are proved to remain finite for any evolution in finite
proper time. We find the novel result that all strong singularities are
resolved for arbitrary matter. Weak singularities pertaining to above potential
curvature divergence events can exist. The effective spacetime is found to be
geodesically complete for particle and null geodesics in finite time evolution.
Our results add to a growing evidence for generic resolution of strong
singularities using effective dynamics in loop quantum cosmology by
generalizing earlier results on isotropic and Bianchi-I spacetimes.
| [
{
"created": "Wed, 15 Jun 2016 19:40:32 GMT",
"version": "v1"
},
{
"created": "Thu, 27 Oct 2016 16:57:18 GMT",
"version": "v2"
}
] | 2017-04-14 | [
[
"Saini",
"Sahil",
""
],
[
"Singh",
"Parampreet",
""
]
] | Resolution of singularities in the Kantowski-Sachs model due to non-perturbative quantum gravity effects is investigated. Using the effective spacetime description for the improved dynamics version of loop quantum Kantowski-Sachs spacetimes, we show that even though expansion and shear scalars are universally bounded, there can exist events where curvature invariants can diverge. However, such events can occur only for very exotic equations of state when pressure or derivatives of energy density with respect to triads become infinite at a finite energy density. In all other cases curvature invariants are proved to remain finite for any evolution in finite proper time. We find the novel result that all strong singularities are resolved for arbitrary matter. Weak singularities pertaining to above potential curvature divergence events can exist. The effective spacetime is found to be geodesically complete for particle and null geodesics in finite time evolution. Our results add to a growing evidence for generic resolution of strong singularities using effective dynamics in loop quantum cosmology by generalizing earlier results on isotropic and Bianchi-I spacetimes. |
1402.4045 | Wei Fang | Wei Fang, Hong Tu, Jiasheng Huang, Chenggang Shu | Dynamical System of Scalar Field from 2-Dimension to 3-D and its
Cosmological Implication | 20 pages, 8 figures,some references added. Minor changes according to
the suggestions from referees | Eur. Phys. J. C (2016) 76:492 | 10.1140/epjc/s10052-016-4340-1 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We give the three-dimensional dynamical autonomous systems for most of the
popular scalar field dark energy models including (phantom) quintessence,
(phantom) tachyon, k-essence and general non-canonical scalar field models,
change the dynamical variables from variables $(x, y, \lambda)$ to observable
related variables $(w_{\phi}, \Omega_{\phi}, \lambda)$, and show the intimate
relationships between those scalar fields that the three-dimensional system of
k-essence can reduce to (phantom) tachyon, general non-canonical scalar field
can reduce to (phantom) quintessence and k-essence can also reduce to (phantom)
quintessence for some special cases. For the applications of the
three-dimensional dynamical systems, we investigate several special cases and
give the exactly dynamical solutions in detail. In the end of this paper, we
argue that, it is more convenient and also has more physical meaning to express
the differential equations of dynamical systems in $(w_{\phi}, \Omega_{\phi},
\lambda)$ instead of variables $(x, y, \lambda)$ and to investigate the
dynamical system in 3-Dimension instead of 2-Dimension. We also raise a
question about the possibility of the chaotic behavior in the spatially flat
single scalar field FRW cosmological models in the presence of ordinary matter.
| [
{
"created": "Mon, 17 Feb 2014 16:11:53 GMT",
"version": "v1"
},
{
"created": "Thu, 17 Apr 2014 03:01:59 GMT",
"version": "v2"
},
{
"created": "Mon, 12 Sep 2016 11:37:29 GMT",
"version": "v3"
}
] | 2016-09-13 | [
[
"Fang",
"Wei",
""
],
[
"Tu",
"Hong",
""
],
[
"Huang",
"Jiasheng",
""
],
[
"Shu",
"Chenggang",
""
]
] | We give the three-dimensional dynamical autonomous systems for most of the popular scalar field dark energy models including (phantom) quintessence, (phantom) tachyon, k-essence and general non-canonical scalar field models, change the dynamical variables from variables $(x, y, \lambda)$ to observable related variables $(w_{\phi}, \Omega_{\phi}, \lambda)$, and show the intimate relationships between those scalar fields that the three-dimensional system of k-essence can reduce to (phantom) tachyon, general non-canonical scalar field can reduce to (phantom) quintessence and k-essence can also reduce to (phantom) quintessence for some special cases. For the applications of the three-dimensional dynamical systems, we investigate several special cases and give the exactly dynamical solutions in detail. In the end of this paper, we argue that, it is more convenient and also has more physical meaning to express the differential equations of dynamical systems in $(w_{\phi}, \Omega_{\phi}, \lambda)$ instead of variables $(x, y, \lambda)$ and to investigate the dynamical system in 3-Dimension instead of 2-Dimension. We also raise a question about the possibility of the chaotic behavior in the spatially flat single scalar field FRW cosmological models in the presence of ordinary matter. |
gr-qc/0011115 | Gilles Esposito-Farese | G. Esposito-Farese | A phenomenological approach to quintessence in scalar-tensor gravity | 2 pages, "mprocl.sty" with LaTeX 2.09; contribution to the 9th Marcel
Grossmann Meeting (MG9), Rome, July 2000 | Proceedings World Scientific (2002) p. 1749 | null | null | gr-qc astro-ph | null | This talk is based on my work in collaboration with B. Boisseau, D. Polarski,
and A.A. Starobinsky. The most natural and best-motivated alternatives to
general relativity are the so-called "scalar-tensor" theories, in which the
gravitational interaction is mediated not only by a (spin-2) graviton, but also
by a (spin-0) scalar field. We study quintessence in this general framework,
and show that the microscopic Lagrangian of the theory can be unambiguously
reconstructed from two observable cosmological functions of the redshift: the
luminosity distance and the linear density perturbation of dustlike matter. We
also analyze the constraints imposed on the theory by the knowledge of only the
first of these functions, as it will probably be available sooner with a good
accuracy. [The main interest of this very short paper is to give the equations
in the "Brans-Dicke" parametrization.]
| [
{
"created": "Thu, 30 Nov 2000 18:24:01 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Esposito-Farese",
"G.",
""
]
] | This talk is based on my work in collaboration with B. Boisseau, D. Polarski, and A.A. Starobinsky. The most natural and best-motivated alternatives to general relativity are the so-called "scalar-tensor" theories, in which the gravitational interaction is mediated not only by a (spin-2) graviton, but also by a (spin-0) scalar field. We study quintessence in this general framework, and show that the microscopic Lagrangian of the theory can be unambiguously reconstructed from two observable cosmological functions of the redshift: the luminosity distance and the linear density perturbation of dustlike matter. We also analyze the constraints imposed on the theory by the knowledge of only the first of these functions, as it will probably be available sooner with a good accuracy. [The main interest of this very short paper is to give the equations in the "Brans-Dicke" parametrization.] |
1304.3683 | Pierre Teyssandier | Bernard Linet and Pierre Teyssandier | New method for determining the light travel time in static, spherically
symmetric spacetimes. Calculation of the terms of order $G^3$ | 24 pages; Eq. (114) corrected; published in Classical and Quantum
Gravity with a Corrigendum | Class. Quantum Grav. 30 (2013) 175008; Corrigendum-Class. Quantum
Grav. 31 (2014) 079502 | 10.1088/0264-9381/30/17/175008 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A new iterative method for calculating the travel time of a photon as a
function of the spatial positions of the emitter and the receiver in the field
of a static, spherically symmetric body is presented. The components of the
metric are assumed to be expressible in power series in $m/r$, with $m$ being
half the Schwarzschild radius of the central body and $r$ a radial coordinate.
The procedure exclusively works for a light ray which may be described as a
perturbation in powers of $G$ of a Minkowskian null geodesic, with $G$ being
the Newtonian gravitational constant. It is shown that the expansion of the
travel time of a photon along such a ray only involves elementary integrals
whatever the order of approximation. An expansion of the impact parameter in
power series of $G$ is also obtained. The method is applied to explicitly
calculate the perturbation expansions of the light travel time and the impact
parameter up to the third order. The full expressions yielding the terms of
order $G^3$ are new. The expression of the travel time confirms the existence
of a third-order enhanced term when the emitter and the receiver are in
conjunction relative to the central body. This term is shown to be necessary
for determining the post-Newtonian parameter $\gamma$ at a level of accuracy of
$10^{-8}$ with light rays grazing the Sun.
| [
{
"created": "Fri, 12 Apr 2013 17:04:40 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Jul 2013 13:08:25 GMT",
"version": "v2"
},
{
"created": "Wed, 9 Apr 2014 14:38:15 GMT",
"version": "v3"
}
] | 2015-06-15 | [
[
"Linet",
"Bernard",
""
],
[
"Teyssandier",
"Pierre",
""
]
] | A new iterative method for calculating the travel time of a photon as a function of the spatial positions of the emitter and the receiver in the field of a static, spherically symmetric body is presented. The components of the metric are assumed to be expressible in power series in $m/r$, with $m$ being half the Schwarzschild radius of the central body and $r$ a radial coordinate. The procedure exclusively works for a light ray which may be described as a perturbation in powers of $G$ of a Minkowskian null geodesic, with $G$ being the Newtonian gravitational constant. It is shown that the expansion of the travel time of a photon along such a ray only involves elementary integrals whatever the order of approximation. An expansion of the impact parameter in power series of $G$ is also obtained. The method is applied to explicitly calculate the perturbation expansions of the light travel time and the impact parameter up to the third order. The full expressions yielding the terms of order $G^3$ are new. The expression of the travel time confirms the existence of a third-order enhanced term when the emitter and the receiver are in conjunction relative to the central body. This term is shown to be necessary for determining the post-Newtonian parameter $\gamma$ at a level of accuracy of $10^{-8}$ with light rays grazing the Sun. |
0806.4452 | Yong-Wan Kim | Yun Soo Myung, Yong-Wan Kim, Young-Jai Park | Thermodynamics of Gauss-Bonnet black holes revisited | 22 pages, 8 figures, version to appear in EPJC | Eur.Phys.J.C58:337-346,2008 | 10.1140/epjc/s10052-008-0745-9 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the Gauss-Bonnet black hole in five dimensional anti-de Sitter
spacetimes (GBAdS). We analyze all thermodynamic quantities of the GBAdS, which
is characterized by the Gauss-Bonnet coupling $c$ and mass $M$, comparing with
those of the Born-Infeld-AdS (BIAdS), Reissner-Norstr\"om-AdS black holes
(RNAdS), Schwarzschild-AdS (SAdS), and BTZ black holes. For $c<0$ we cannot
obtain the black hole with positively definite thermodynamic quantities of
mass, temperature, and entropy because the entropy does not satisfy the
area-law. On the other hand, for $c>0$, we find the BIAdS-like black hole,
showing that the coupling $c$ plays the role of pseudo-charge. Importantly, we
could not obtain the SAdS in the limits of $c\to 0$, which means that the GBAdS
is basically different from the SAdS. In addition, we clarify the connections
between thermodynamic and dynamical stability. Finally, we also conjecture that
if a black hole is big and thus globally stable, its quasinormal modes may take
analytic expressions.
| [
{
"created": "Fri, 27 Jun 2008 08:30:55 GMT",
"version": "v1"
},
{
"created": "Wed, 2 Jul 2008 07:23:11 GMT",
"version": "v2"
},
{
"created": "Sat, 27 Sep 2008 15:24:49 GMT",
"version": "v3"
}
] | 2008-12-18 | [
[
"Myung",
"Yun Soo",
""
],
[
"Kim",
"Yong-Wan",
""
],
[
"Park",
"Young-Jai",
""
]
] | We investigate the Gauss-Bonnet black hole in five dimensional anti-de Sitter spacetimes (GBAdS). We analyze all thermodynamic quantities of the GBAdS, which is characterized by the Gauss-Bonnet coupling $c$ and mass $M$, comparing with those of the Born-Infeld-AdS (BIAdS), Reissner-Norstr\"om-AdS black holes (RNAdS), Schwarzschild-AdS (SAdS), and BTZ black holes. For $c<0$ we cannot obtain the black hole with positively definite thermodynamic quantities of mass, temperature, and entropy because the entropy does not satisfy the area-law. On the other hand, for $c>0$, we find the BIAdS-like black hole, showing that the coupling $c$ plays the role of pseudo-charge. Importantly, we could not obtain the SAdS in the limits of $c\to 0$, which means that the GBAdS is basically different from the SAdS. In addition, we clarify the connections between thermodynamic and dynamical stability. Finally, we also conjecture that if a black hole is big and thus globally stable, its quasinormal modes may take analytic expressions. |
2208.06731 | Stanley Deser | S.Deser | All identically conserved gravitational tensors are metric variations of
an action | Published version | Annals of Physics 448,169162(2023) | null | BRX-TH-6709; Caltech 2022-028 | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | I prove an old unsolved conjecture, the hard part of its obvious sufficiency,
namely that all identically conserved symmetric two-tensors are necessarily
metric variations of invariant actions, thus sparing the world more alternative
gravity theories. The proof is reasonably simple, if perhaps a physicist's.
| [
{
"created": "Sat, 13 Aug 2022 21:06:31 GMT",
"version": "v1"
},
{
"created": "Tue, 16 Aug 2022 02:46:48 GMT",
"version": "v2"
},
{
"created": "Fri, 16 Dec 2022 00:16:23 GMT",
"version": "v3"
}
] | 2022-12-20 | [
[
"Deser",
"S.",
""
]
] | I prove an old unsolved conjecture, the hard part of its obvious sufficiency, namely that all identically conserved symmetric two-tensors are necessarily metric variations of invariant actions, thus sparing the world more alternative gravity theories. The proof is reasonably simple, if perhaps a physicist's. |
2005.13999 | Shahn Majid | J. N. Argota-Quiroz and S. Majid | Quantum gravity on polygons and $\Bbb R\times \Bbb Z_n$ FLRW model | 40 pages latex, 3 pdf figures. Version 1.6 added Sec 3.2 on the n->
infinity limit of Z_n as a classical circle. This Version 1.7 has only
typo-level corrections relative to that | null | 10.1088/1361-6382/abbaa8 | null | gr-qc math.QA | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We fully solve the quantum geometry of $\Bbb Z_n$ as a polygon graph with
arbitrary metric lengths on the edges, finding a $*$-preserving quantum
Levi-Civita connection which is unique for $n\ne 4$. As a first application, we
numerically compute correlation functions for Euclideanised quantum gravity on
$\Bbb Z_n$ for small $n$. We then study an FLRW model on $\Bbb R\times\Bbb
Z_n$, finding the same expansion rate as for the classical flat FLRW model in
1+2 dimensions. We also look at particle creation on $\Bbb R\times \Bbb Z_n$
and find an additional $m=0$ adiabatic no particle creation expansion as well
as the particle creation spectrum for a smoothed step expansion.
| [
{
"created": "Tue, 26 May 2020 13:31:02 GMT",
"version": "v1"
},
{
"created": "Sat, 26 Sep 2020 10:51:47 GMT",
"version": "v2"
},
{
"created": "Wed, 7 Oct 2020 09:02:36 GMT",
"version": "v3"
}
] | 2020-12-30 | [
[
"Argota-Quiroz",
"J. N.",
""
],
[
"Majid",
"S.",
""
]
] | We fully solve the quantum geometry of $\Bbb Z_n$ as a polygon graph with arbitrary metric lengths on the edges, finding a $*$-preserving quantum Levi-Civita connection which is unique for $n\ne 4$. As a first application, we numerically compute correlation functions for Euclideanised quantum gravity on $\Bbb Z_n$ for small $n$. We then study an FLRW model on $\Bbb R\times\Bbb Z_n$, finding the same expansion rate as for the classical flat FLRW model in 1+2 dimensions. We also look at particle creation on $\Bbb R\times \Bbb Z_n$ and find an additional $m=0$ adiabatic no particle creation expansion as well as the particle creation spectrum for a smoothed step expansion. |
1504.00524 | Ivan Kolar | Ivan Kolar, Pavel Krtous | Weak electromagnetic field admitting integrability in Kerr-NUT-(A)dS
spacetimes | 12 pages, 0 figures | Phys. Rev. D 91, 124045, 2015 | 10.1103/PhysRevD.91.124045 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate properties of higher-dimensional generally rotating black-hole
spacetimes, so called Kerr-NUT-(A)dS spacetimes, as well as a family of related
spaces which share the same explicit and hidden symmetries. In these spaces, we
study a particle motion in the presence of a weak electromagnetic field and
compare it with its operator analogies. First, we find general commutativity
conditions for classical observables and for their operator counterparts, then
we investigate a fulfillment of these conditions in the Kerr-NUT-(A)dS and
related spaces. We find the most general form of the weak electromagnetic field
compatible with the complete integrability of the particle motion and the
comutativity of the field operators. For such a field we solve the charged
Hamilton-Jacobi and Klein-Gordon equations by separation of variables.
| [
{
"created": "Thu, 2 Apr 2015 12:32:16 GMT",
"version": "v1"
},
{
"created": "Wed, 17 Jun 2015 12:04:43 GMT",
"version": "v2"
}
] | 2015-06-18 | [
[
"Kolar",
"Ivan",
""
],
[
"Krtous",
"Pavel",
""
]
] | We investigate properties of higher-dimensional generally rotating black-hole spacetimes, so called Kerr-NUT-(A)dS spacetimes, as well as a family of related spaces which share the same explicit and hidden symmetries. In these spaces, we study a particle motion in the presence of a weak electromagnetic field and compare it with its operator analogies. First, we find general commutativity conditions for classical observables and for their operator counterparts, then we investigate a fulfillment of these conditions in the Kerr-NUT-(A)dS and related spaces. We find the most general form of the weak electromagnetic field compatible with the complete integrability of the particle motion and the comutativity of the field operators. For such a field we solve the charged Hamilton-Jacobi and Klein-Gordon equations by separation of variables. |
gr-qc/9704035 | null | S. Mignemi | Spherically symmetric solutions in four-dimensional Poincar\'e gravity
with non-trivial torsion | 12 pages, plain TeX | Class.Quant.Grav.15:299-307,1998 | 10.1088/0264-9381/15/2/005 | INFNCA-TH9704 | gr-qc | null | We study a four-dimensional gauge theory of the Poincar\'e group with
topological action which generalizes some well-known two-dimensional gravity
models. We classify the spherically symmetric solutions and discuss the
perturbative propagation of excitations around flat spacetime.
| [
{
"created": "Mon, 14 Apr 1997 11:51:05 GMT",
"version": "v1"
}
] | 2010-11-19 | [
[
"Mignemi",
"S.",
""
]
] | We study a four-dimensional gauge theory of the Poincar\'e group with topological action which generalizes some well-known two-dimensional gravity models. We classify the spherically symmetric solutions and discuss the perturbative propagation of excitations around flat spacetime. |
2004.06810 | Astrid Eichhorn | Alfio Bonanno, Astrid Eichhorn, Holger Gies, Jan M. Pawlowski, Roberto
Percacci, Martin Reuter, Frank Saueressig, Gian Paolo Vacca | Critical reflections on asymptotically safe gravity | 23 pages plus references | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Asymptotic safety is a theoretical proposal for the ultraviolet completion of
quantum field theories, in particular for quantum gravity. Significant progress
on this program has led to a first characterization of the Reuter fixed point.
Further advancement in our understanding of the nature of quantum spacetime
requires addressing a number of open questions and challenges. Here, we aim at
providing a critical reflection on the state of the art in the asymptotic
safety program, specifying and elaborating on open questions of both technical
and conceptual nature. We also point out systematic pathways, in various stages
of practical implementation, towards answering them. Finally, we also take the
opportunity to clarify some common misunderstandings regarding the program.
| [
{
"created": "Tue, 14 Apr 2020 21:28:42 GMT",
"version": "v1"
}
] | 2020-04-16 | [
[
"Bonanno",
"Alfio",
""
],
[
"Eichhorn",
"Astrid",
""
],
[
"Gies",
"Holger",
""
],
[
"Pawlowski",
"Jan M.",
""
],
[
"Percacci",
"Roberto",
""
],
[
"Reuter",
"Martin",
""
],
[
"Saueressig",
"Frank",
""
],
... | Asymptotic safety is a theoretical proposal for the ultraviolet completion of quantum field theories, in particular for quantum gravity. Significant progress on this program has led to a first characterization of the Reuter fixed point. Further advancement in our understanding of the nature of quantum spacetime requires addressing a number of open questions and challenges. Here, we aim at providing a critical reflection on the state of the art in the asymptotic safety program, specifying and elaborating on open questions of both technical and conceptual nature. We also point out systematic pathways, in various stages of practical implementation, towards answering them. Finally, we also take the opportunity to clarify some common misunderstandings regarding the program. |
gr-qc/0109068 | Ariel Caticha | Ariel Caticha | Entropic Dynamics | Presented at MaxEnt 2001, the 21th International Workshop on Bayesian
Inference and Maximum Entropy Methods (August 4-9, 2001, Baltimore, MD, USA) | AIP Conf.Proc. 617 (2002) 302 | 10.1063/1.1477054 | null | gr-qc cond-mat.stat-mech physics.class-ph | null | I explore the possibility that the laws of physics might be laws of inference
rather than laws of nature. What sort of dynamics can one derive from
well-established rules of inference? Specifically, I ask: Given relevant
information codified in the initial and the final states, what trajectory is
the system expected to follow? The answer follows from a principle of
inference, the principle of maximum entropy, and not from a principle of
physics. The entropic dynamics derived this way exhibits some remarkable formal
similarities with other generally covariant theories such as general
relativity.
| [
{
"created": "Wed, 19 Sep 2001 13:36:39 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Caticha",
"Ariel",
""
]
] | I explore the possibility that the laws of physics might be laws of inference rather than laws of nature. What sort of dynamics can one derive from well-established rules of inference? Specifically, I ask: Given relevant information codified in the initial and the final states, what trajectory is the system expected to follow? The answer follows from a principle of inference, the principle of maximum entropy, and not from a principle of physics. The entropic dynamics derived this way exhibits some remarkable formal similarities with other generally covariant theories such as general relativity. |
2306.04145 | Yang Huang | Yang Huang, Zhoujian Cao, Zhenyan Lu | Generalized Gibbons-Werner method for stationary spacetimes | null | Journal of Cosmology and Astroparticle Physics, 01 (2024) 013 | 10.1088/1475-7516/2024/01/013 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Gibbons-Werner (GW) method is a powerful approach in studying the
gravitational deflection of particles moving in curved spacetimes. The
application of the Gauss-Bonnet theorem (GBT) to integral regions constructed
in a two-dimensional manifold enables the deflection angle to be expressed and
calculated from the perspective of geometry. However, different techniques are
required for different scenarios in the practical implementation which leads to
different GW methods. For the GW method for stationary axially symmetric (SAS)
spacetimes, we identify two problems: (a) the integral region is generally
infinite, which is ill-defined for some asymptotically nonflat spacetimes whose
metric possesses singular behavior, and (b) the intricate double and single
integrals bring about complicated calculation, especially for highly accurate
results and complex spacetimes. To address these issues, a generalized GW
method is proposed in which the infinite region is replaced by a flexible
region to avoid the singularity, and a simplified formula involving only a
single integral of a simple integrand is derived by discovering a significant
relationship between the integrals in conventional methods. Our method provides
a comprehensive framework for describing the GW method for various scenarios.
Additionally, the generalized GW method and simplified calculation formula are
applied to three different kinds of spacetimes--Kerr spacetime, Kerr-like black
hole in bumblebee gravity, and rotating solution in conformal Weyl gravity. The
first two cases have been previously computed by other researchers, affirming
the effectiveness and superiority of our approach. Remarkably, the third case
is newly examined, yielding an innovative result for the first time.
| [
{
"created": "Wed, 7 Jun 2023 04:44:29 GMT",
"version": "v1"
},
{
"created": "Wed, 25 Oct 2023 09:52:16 GMT",
"version": "v2"
},
{
"created": "Fri, 24 Nov 2023 16:29:30 GMT",
"version": "v3"
},
{
"created": "Wed, 10 Jan 2024 14:29:55 GMT",
"version": "v4"
}
] | 2024-01-11 | [
[
"Huang",
"Yang",
""
],
[
"Cao",
"Zhoujian",
""
],
[
"Lu",
"Zhenyan",
""
]
] | The Gibbons-Werner (GW) method is a powerful approach in studying the gravitational deflection of particles moving in curved spacetimes. The application of the Gauss-Bonnet theorem (GBT) to integral regions constructed in a two-dimensional manifold enables the deflection angle to be expressed and calculated from the perspective of geometry. However, different techniques are required for different scenarios in the practical implementation which leads to different GW methods. For the GW method for stationary axially symmetric (SAS) spacetimes, we identify two problems: (a) the integral region is generally infinite, which is ill-defined for some asymptotically nonflat spacetimes whose metric possesses singular behavior, and (b) the intricate double and single integrals bring about complicated calculation, especially for highly accurate results and complex spacetimes. To address these issues, a generalized GW method is proposed in which the infinite region is replaced by a flexible region to avoid the singularity, and a simplified formula involving only a single integral of a simple integrand is derived by discovering a significant relationship between the integrals in conventional methods. Our method provides a comprehensive framework for describing the GW method for various scenarios. Additionally, the generalized GW method and simplified calculation formula are applied to three different kinds of spacetimes--Kerr spacetime, Kerr-like black hole in bumblebee gravity, and rotating solution in conformal Weyl gravity. The first two cases have been previously computed by other researchers, affirming the effectiveness and superiority of our approach. Remarkably, the third case is newly examined, yielding an innovative result for the first time. |
2101.05530 | K\'aroly Zolt\'an Csuk\'as | K\'aroly Zolt\'an Csuk\'as and Istv\'an R\'acz | Numerical investigation of the dynamics of linear spin $s$ fields on a
Kerr background II: Superradiant scattering | 45 pages, 26 figures | Phys. Rev. D 103, 084035 (2021) | 10.1103/PhysRevD.103.084035 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Superradiant scattering of linear spin $s=0,\pm 1,\pm 2$ fields on Kerr black
hole background is investigated in the time domain by integrating numerically
the homogeneous Teukolsky master equation. The applied numerical setup has
already been used in studying long time evolution and tail behavior of
electromagnetic and metric perturbations on rotating black hole background
[arXiv:1905.09082v3]. To have a clear setup the initial data is chosen to be of
the compact support, while to optimize superradiance the frequency of the
initial data is fine tuned. Our most important finding is that the rate of
superradiance strongly depends on the relative position of the (compact)
support of the initial data and the ergoregion. When they are well-separated
then only a modest -- in case of $s=0$ scalar fields negligible --
superradiance occurs, whereas it can get to be amplified significantly whenever
the support of the initial data and the ergoregion overlap.
| [
{
"created": "Thu, 14 Jan 2021 10:04:57 GMT",
"version": "v1"
},
{
"created": "Fri, 23 Apr 2021 10:48:20 GMT",
"version": "v2"
}
] | 2021-04-26 | [
[
"Csukás",
"Károly Zoltán",
""
],
[
"Rácz",
"István",
""
]
] | Superradiant scattering of linear spin $s=0,\pm 1,\pm 2$ fields on Kerr black hole background is investigated in the time domain by integrating numerically the homogeneous Teukolsky master equation. The applied numerical setup has already been used in studying long time evolution and tail behavior of electromagnetic and metric perturbations on rotating black hole background [arXiv:1905.09082v3]. To have a clear setup the initial data is chosen to be of the compact support, while to optimize superradiance the frequency of the initial data is fine tuned. Our most important finding is that the rate of superradiance strongly depends on the relative position of the (compact) support of the initial data and the ergoregion. When they are well-separated then only a modest -- in case of $s=0$ scalar fields negligible -- superradiance occurs, whereas it can get to be amplified significantly whenever the support of the initial data and the ergoregion overlap. |
2006.08652 | John Barrow | John D. Barrow | Multifractality in the general cosmological solution of Einstein's
equations | 5 pages, no figures, extra text and refs, accepted version | Phys. Rev. D 102, 041501 (2020) | 10.1103/PhysRevD.102.041501 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We demonstrate the scale invariance of the vacuum Bianchi type IX equations
and use this to argue for the possibility of multifractal turbulence as a
realisation of the suggestion by Belinski that there will be a fragmentation of
local regions of inhomogeneous Mixmaster chaos on approach to an initial
inhomogeneous cosmological singularity. Differences between the gravitational
and hydrodynamical situations are outlined. Various potential obstacles to this
picture of gravitational turbulence are discussed.
| [
{
"created": "Mon, 15 Jun 2020 18:03:27 GMT",
"version": "v1"
},
{
"created": "Tue, 21 Jul 2020 15:19:46 GMT",
"version": "v2"
}
] | 2020-08-12 | [
[
"Barrow",
"John D.",
""
]
] | We demonstrate the scale invariance of the vacuum Bianchi type IX equations and use this to argue for the possibility of multifractal turbulence as a realisation of the suggestion by Belinski that there will be a fragmentation of local regions of inhomogeneous Mixmaster chaos on approach to an initial inhomogeneous cosmological singularity. Differences between the gravitational and hydrodynamical situations are outlined. Various potential obstacles to this picture of gravitational turbulence are discussed. |
1805.08070 | Remya Nair | Remya Nair and Takahiro Tanaka | Synergy between ground and space based gravitational wave detectors II:
Localisation | one modified figure, results unchanged | null | 10.1088/1475-7516/2018/08/033 | KUNS-2722, YITP-18-53 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the advantage of combining measurements from future ground and space
based gravitational wave detectors in estimating the parameters of a black-hole
binary coalescence. This is an extension of our previous work (PTEP 053E01
(2016)) where we used pattern averaged waveform to study non-spinning binaries.
In this work we study the localisation and binary plane orientation, including
the (non-precessing) spin of binaries. We focus on the third generation
terrestrial detector `Einstein telescope' and a proposed space based detector
`Deci-Hertz Interferometer Gravitational wave Observatory' (DECIGO). We
consider two possible orbits for DECIGO, a heliocentric orbit and a
Sun-synchronous geocentric orbit. We demonstrate that one can obtain order of
magnitude improvement in the localisation from the space-ground combined
measurements, even with a precursor-DECIGO mission (B-DECIGO). This is
especially important for the future of gravitational wave astronomy as
improving the localisation accuracy further improves our chances of identifying
the host galaxies of these binary systems.
| [
{
"created": "Fri, 18 May 2018 03:48:54 GMT",
"version": "v1"
},
{
"created": "Fri, 27 Jul 2018 08:14:19 GMT",
"version": "v2"
},
{
"created": "Wed, 14 Nov 2018 21:26:38 GMT",
"version": "v3"
}
] | 2018-11-16 | [
[
"Nair",
"Remya",
""
],
[
"Tanaka",
"Takahiro",
""
]
] | We study the advantage of combining measurements from future ground and space based gravitational wave detectors in estimating the parameters of a black-hole binary coalescence. This is an extension of our previous work (PTEP 053E01 (2016)) where we used pattern averaged waveform to study non-spinning binaries. In this work we study the localisation and binary plane orientation, including the (non-precessing) spin of binaries. We focus on the third generation terrestrial detector `Einstein telescope' and a proposed space based detector `Deci-Hertz Interferometer Gravitational wave Observatory' (DECIGO). We consider two possible orbits for DECIGO, a heliocentric orbit and a Sun-synchronous geocentric orbit. We demonstrate that one can obtain order of magnitude improvement in the localisation from the space-ground combined measurements, even with a precursor-DECIGO mission (B-DECIGO). This is especially important for the future of gravitational wave astronomy as improving the localisation accuracy further improves our chances of identifying the host galaxies of these binary systems. |
2111.01362 | Jiong Lin | Jiong Lin, Shengqing Gao, Yungui Gong, Yizhou Lu, Zhongkai Wang,
Fengge Zhang | Primordial black holes and scalar induced gravitational waves from Higgs
inflation with non-canonical kinetic term | null | null | null | null | gr-qc astro-ph.CO hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We resolve the potential-restriction problem in K/G inflation by introducing
nonminimal coupling. In this context, Higgs field successfully drives inflation
satisfying CMB observations while enhancing curvature perturbations at small
scales, which in turn accounts for primordial black holes (PBHs) and scalar
induced gravitational waves (SIGWs). We then uncover the effect of the
non-canonical kinetic coupling function in more detail and study its the
observational constraint. Besides, we also give the gauge invariant expression
for the integral kernel of SIGWs, which is related to terms propagating with
the speed of light. Finally, the non-Gaussian effect on PBH abundance and SIGWs
is studied. We find that non-Gaussianity makes PBHs form more easily, but its
effect on the energy density of SIGWs is negligible.
| [
{
"created": "Tue, 2 Nov 2021 04:15:17 GMT",
"version": "v1"
},
{
"created": "Wed, 3 Nov 2021 09:56:05 GMT",
"version": "v2"
},
{
"created": "Wed, 1 Feb 2023 15:00:35 GMT",
"version": "v3"
}
] | 2023-02-02 | [
[
"Lin",
"Jiong",
""
],
[
"Gao",
"Shengqing",
""
],
[
"Gong",
"Yungui",
""
],
[
"Lu",
"Yizhou",
""
],
[
"Wang",
"Zhongkai",
""
],
[
"Zhang",
"Fengge",
""
]
] | We resolve the potential-restriction problem in K/G inflation by introducing nonminimal coupling. In this context, Higgs field successfully drives inflation satisfying CMB observations while enhancing curvature perturbations at small scales, which in turn accounts for primordial black holes (PBHs) and scalar induced gravitational waves (SIGWs). We then uncover the effect of the non-canonical kinetic coupling function in more detail and study its the observational constraint. Besides, we also give the gauge invariant expression for the integral kernel of SIGWs, which is related to terms propagating with the speed of light. Finally, the non-Gaussian effect on PBH abundance and SIGWs is studied. We find that non-Gaussianity makes PBHs form more easily, but its effect on the energy density of SIGWs is negligible. |
1706.09383 | Pierre Fleury | Pierre Fleury, Julien Larena, Jean-Philippe Uzan | Weak gravitational lensing of finite beams | 6 pages, 2 figures, v2: matches published version, some typos
corrected | Phys. Rev. Lett. 119, 191101 (2017) | 10.1103/PhysRevLett.119.191101 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The standard theory of weak gravitational lensing relies on the infinitesimal
light beam approximation. In this context, images are distorted by convergence
and shear, the respective sources of which unphysically depend on the
resolution of the distribution of matter---the so-called Ricci-Weyl problem. In
this letter, we propose a strong-lensing-inspired formalism to describe the
lensing of finite beams. We address the Ricci-Weyl problem by showing
explicitly that convergence is caused by the matter enclosed by the beam,
regardless of its distribution. Furthermore, shear turns out to be
systematically enhanced by the finiteness of the beam. This implies, in
particular, that the Kaiser-Squires relation between shear and convergence is
violated, which could have profound consequences on the interpretation of weak
lensing surveys.
| [
{
"created": "Wed, 28 Jun 2017 17:50:32 GMT",
"version": "v1"
},
{
"created": "Tue, 7 Nov 2017 10:38:08 GMT",
"version": "v2"
}
] | 2017-11-08 | [
[
"Fleury",
"Pierre",
""
],
[
"Larena",
"Julien",
""
],
[
"Uzan",
"Jean-Philippe",
""
]
] | The standard theory of weak gravitational lensing relies on the infinitesimal light beam approximation. In this context, images are distorted by convergence and shear, the respective sources of which unphysically depend on the resolution of the distribution of matter---the so-called Ricci-Weyl problem. In this letter, we propose a strong-lensing-inspired formalism to describe the lensing of finite beams. We address the Ricci-Weyl problem by showing explicitly that convergence is caused by the matter enclosed by the beam, regardless of its distribution. Furthermore, shear turns out to be systematically enhanced by the finiteness of the beam. This implies, in particular, that the Kaiser-Squires relation between shear and convergence is violated, which could have profound consequences on the interpretation of weak lensing surveys. |
2109.02143 | Francisco Jos\'e Maldonado Torralba | Ivan Kol\'a\v{r}, Francisco Jos\'e Maldonado Torralba, Anupam Mazumdar | New non-singular cosmological solution of non-local gravity | 12 pages | Phys. Rev. D 105, 044045 (2022) | 10.1103/PhysRevD.105.044045 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a new bouncing cosmological solution of the non-local theory known
as infinite derivative gravity, which goes beyond the recursive ansatz, ${\Box
R = r_1 R +r_2}$. The non-local field equations are evaluated using the
spectral decomposition with respect to the eigenfunctions of the wave operator.
The energy-momentum tensor computed for this geometry turns out to be much more
sensitive to the choice of the non-local form-factor, since it depends on the
value of the function on a continuous infinite interval. We show that this
stronger dependence on the form-factor allows us to source the geometry by the
perfect fluid with the non-negative energy density satisfying the strong energy
condition. We show that this bouncing behaviour is not possible in the local
theories of gravity such as in general relativity or $R+R^2$ gravity sourced by
a fluid which meets the non-negative energy and strong energy conditions.
| [
{
"created": "Sun, 5 Sep 2021 18:37:59 GMT",
"version": "v1"
}
] | 2022-02-24 | [
[
"Kolář",
"Ivan",
""
],
[
"Torralba",
"Francisco José Maldonado",
""
],
[
"Mazumdar",
"Anupam",
""
]
] | We present a new bouncing cosmological solution of the non-local theory known as infinite derivative gravity, which goes beyond the recursive ansatz, ${\Box R = r_1 R +r_2}$. The non-local field equations are evaluated using the spectral decomposition with respect to the eigenfunctions of the wave operator. The energy-momentum tensor computed for this geometry turns out to be much more sensitive to the choice of the non-local form-factor, since it depends on the value of the function on a continuous infinite interval. We show that this stronger dependence on the form-factor allows us to source the geometry by the perfect fluid with the non-negative energy density satisfying the strong energy condition. We show that this bouncing behaviour is not possible in the local theories of gravity such as in general relativity or $R+R^2$ gravity sourced by a fluid which meets the non-negative energy and strong energy conditions. |
gr-qc/9608065 | O. Yu. Shvedov | V.A.Rubakov and O.Yu.Shvedov | Instability of Space-Time due to Euclidean Wormholes | 9 pages in LaTeX, 3 figures in PostScript, to appear in Proceedings
of the 9th International Seminar "QUARKS-96" | null | null | null | gr-qc | null | The problem of topology change transitions in quantum gravity is discussed.
We argue that the contribution of the Giddings-Strominger wormhole to the
Euclidean path integral is pure imaginary. This is checked by two techniques:
by the functional integral approach and by the analysis of the Wheeler-De Witt
equation. We present also a simple quantum mechanical model which shares many
features of the system consisting of parent and baby universes. In this simple
model, we show that quantum coherence is completely lost and obtain the
equation for the effective density matrix of the ''parent universe''.
| [
{
"created": "Wed, 28 Aug 1996 10:47:14 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Rubakov",
"V. A.",
""
],
[
"Shvedov",
"O. Yu.",
""
]
] | The problem of topology change transitions in quantum gravity is discussed. We argue that the contribution of the Giddings-Strominger wormhole to the Euclidean path integral is pure imaginary. This is checked by two techniques: by the functional integral approach and by the analysis of the Wheeler-De Witt equation. We present also a simple quantum mechanical model which shares many features of the system consisting of parent and baby universes. In this simple model, we show that quantum coherence is completely lost and obtain the equation for the effective density matrix of the ''parent universe''. |
2006.15496 | Masashi Kimura | Yasuyuki Hatsuda and Masashi Kimura | Semi-analytic expressions for quasinormal modes of slowly rotating Kerr
black holes | 19 pages, 22 figures, v2: minor revisions, v3: minor revisions,
accepted for publication in Phys. Rev. D | Phys. Rev. D 102, 044032 (2020) | 10.1103/PhysRevD.102.044032 | RUP-20-23 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide semi-analytic expressions for quasinormal mode frequencies of
slowly rotating Kerr black holes to the quadratic order in the rotation
parameter. We apply the parametrized black hole quasinormal mode ringdown
formalism to the Chandrasekhar-Detweiler equation and the Sasaki-Nakamura
equation instead of the Teukolsky equation, and compare our result with the
previous numerical calculations.
| [
{
"created": "Sun, 28 Jun 2020 03:43:21 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Jul 2020 04:01:24 GMT",
"version": "v2"
},
{
"created": "Wed, 5 Aug 2020 15:04:48 GMT",
"version": "v3"
}
] | 2020-08-26 | [
[
"Hatsuda",
"Yasuyuki",
""
],
[
"Kimura",
"Masashi",
""
]
] | We provide semi-analytic expressions for quasinormal mode frequencies of slowly rotating Kerr black holes to the quadratic order in the rotation parameter. We apply the parametrized black hole quasinormal mode ringdown formalism to the Chandrasekhar-Detweiler equation and the Sasaki-Nakamura equation instead of the Teukolsky equation, and compare our result with the previous numerical calculations. |
1911.07998 | Atul Divakarla | Atul K. Divakarla, Eric Thrane, Paul D. Lasky, Bernard F. Whiting | Memory Effect or Cosmic String? Classifying Gravitational-Wave Bursts
with Bayesian Inference | 7 pages, 4 figures | Phys. Rev. D 102, 023010 (2020) | 10.1103/PhysRevD.102.023010 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A variety of gravitational-wave transient sources can be modeled in the
Fourier domain using a power law. This simple power-law model provides a
reasonable approximation for gravitational-wave bursts from cosmic string
cusps, cosmic string kinks, and the memory effect. Each of these sources is
described using a different spectral index. In this work, we simulate
interferometer strain data with injections of power-law and memory bursts to
demonstrate parameter estimation, signal detection, and model selection. We
show how Bayesian inference can be used to measure the power-law spectral
index, thereby distinguishing between different astrophysical scenarios.
| [
{
"created": "Mon, 18 Nov 2019 23:06:16 GMT",
"version": "v1"
},
{
"created": "Sun, 28 Jun 2020 15:58:13 GMT",
"version": "v2"
}
] | 2020-07-15 | [
[
"Divakarla",
"Atul K.",
""
],
[
"Thrane",
"Eric",
""
],
[
"Lasky",
"Paul D.",
""
],
[
"Whiting",
"Bernard F.",
""
]
] | A variety of gravitational-wave transient sources can be modeled in the Fourier domain using a power law. This simple power-law model provides a reasonable approximation for gravitational-wave bursts from cosmic string cusps, cosmic string kinks, and the memory effect. Each of these sources is described using a different spectral index. In this work, we simulate interferometer strain data with injections of power-law and memory bursts to demonstrate parameter estimation, signal detection, and model selection. We show how Bayesian inference can be used to measure the power-law spectral index, thereby distinguishing between different astrophysical scenarios. |
2108.04210 | Jeremy Peters | Alan Coley, Jeremy M Peters and Erik Schnetter | Geometric horizons in binary black hole mergers | Paper published as Letter in Class. Quant. Grav vol38, 17LT01 (2021).
arXiv admin note: text overlap with arXiv:2101.09615 | Class. Quantum Grav. 38 17LT01 (2021) | 10.1088/1361-6382/ac10ed | null | gr-qc | http://creativecommons.org/licenses/by-sa/4.0/ | We numerically study the algebraic properties of the Weyl tensor through the
merger of two non-spinning black holes (BHs). We are particularly interested in
the conjecture that for such a vacuum spacetime, which is zeroth-order
algebraically general, a geometric horizon (GH), on which the spacetime is
algebraically special and which is identified by the vanishing of a complex
scalar invariant (${\mathcal{D}}$), characterizes a smooth foliation
independent surface (horizon) associated with the BH. In the first simulation
we investigate the level-$0$ sets of $\text{Re}({\mathcal{D}})$ (since
$\text{Im}({\mathcal{D}})= 0$) in the head-on collision of two unequal mass
BHs. In the second simulation we shall investigate the level-$\varepsilon$ sets
of $|{\mathcal{D}}|$ through a quasi-circular merger of two non-spinning, equal
mass BHs. The numerical results, as displayed in the figures presented, provide
evidence that a (unique) smooth GH can be identified throughout all stages of
the binary BH merger.
| [
{
"created": "Mon, 9 Aug 2021 17:52:30 GMT",
"version": "v1"
}
] | 2021-09-01 | [
[
"Coley",
"Alan",
""
],
[
"Peters",
"Jeremy M",
""
],
[
"Schnetter",
"Erik",
""
]
] | We numerically study the algebraic properties of the Weyl tensor through the merger of two non-spinning black holes (BHs). We are particularly interested in the conjecture that for such a vacuum spacetime, which is zeroth-order algebraically general, a geometric horizon (GH), on which the spacetime is algebraically special and which is identified by the vanishing of a complex scalar invariant (${\mathcal{D}}$), characterizes a smooth foliation independent surface (horizon) associated with the BH. In the first simulation we investigate the level-$0$ sets of $\text{Re}({\mathcal{D}})$ (since $\text{Im}({\mathcal{D}})= 0$) in the head-on collision of two unequal mass BHs. In the second simulation we shall investigate the level-$\varepsilon$ sets of $|{\mathcal{D}}|$ through a quasi-circular merger of two non-spinning, equal mass BHs. The numerical results, as displayed in the figures presented, provide evidence that a (unique) smooth GH can be identified throughout all stages of the binary BH merger. |
1011.5329 | Clovis Jacinto de Matos | Clovis Jacinto de Matos | Coincident-Frequency Entangled Photons in a Homogenous Gravitational
Field - A Thought Experiment | principle of equivalence, entangled photons, gravitational redshift | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Assuming that the Principle of energy conservation holds for
coincident-frequency entangled photons propagating in a homogeneous
gravitational field. It is argued that in this physical context, either Quantum
entanglement or the weak equivalence principle are broken by the photons.
| [
{
"created": "Wed, 24 Nov 2010 09:53:49 GMT",
"version": "v1"
}
] | 2010-11-25 | [
[
"de Matos",
"Clovis Jacinto",
""
]
] | Assuming that the Principle of energy conservation holds for coincident-frequency entangled photons propagating in a homogeneous gravitational field. It is argued that in this physical context, either Quantum entanglement or the weak equivalence principle are broken by the photons. |
0807.0734 | Ronny Richter | Ronny Richter, Christian Lubich | Free and constrained symplectic integrators for numerical general
relativity | 25 pages, 7 figures; This version contains minor clarifications and
corrections | Class.Quant.Grav.25:225018,2008 | 10.1088/0264-9381/25/22/225018 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider symplectic time integrators in numerical General Relativity and
discuss both free and constrained evolution schemes. For free evolution of
ADM-like equations we propose the use of the Stoermer-Verlet method, a standard
symplectic integrator which here is explicit in the computationally expensive
curvature terms. For the constrained evolution we give a formulation of the
evolution equations that enforces the momentum constraints in a holonomically
constrained Hamiltonian system and turns the Hamilton constraint function from
a weak to a strong invariant of the system. This formulation permits the use of
the constraint-preserving symplectic RATTLE integrator, a constrained version
of the Stoermer-Verlet method.
The behavior of the methods is illustrated on two effectively 1+1-dimensional
versions of Einstein's equations, that allow to investigate a perturbed
Minkowski problem and the Schwarzschild space-time. We compare symplectic and
non-symplectic integrators for free evolution, showing very different numerical
behavior for nearly-conserved quantities in the perturbed Minkowski problem.
Further we compare free and constrained evolution, demonstrating in our
examples that enforcing the momentum constraints can turn an unstable free
evolution into a stable constrained evolution. This is demonstrated in the
stabilization of a perturbed Minkowski problem with Dirac gauge, and in the
suppression of the propagation of boundary instabilities into the interior of
the domain in Schwarzschild space-time.
| [
{
"created": "Mon, 7 Jul 2008 06:08:42 GMT",
"version": "v1"
},
{
"created": "Tue, 4 Nov 2008 08:03:14 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Richter",
"Ronny",
""
],
[
"Lubich",
"Christian",
""
]
] | We consider symplectic time integrators in numerical General Relativity and discuss both free and constrained evolution schemes. For free evolution of ADM-like equations we propose the use of the Stoermer-Verlet method, a standard symplectic integrator which here is explicit in the computationally expensive curvature terms. For the constrained evolution we give a formulation of the evolution equations that enforces the momentum constraints in a holonomically constrained Hamiltonian system and turns the Hamilton constraint function from a weak to a strong invariant of the system. This formulation permits the use of the constraint-preserving symplectic RATTLE integrator, a constrained version of the Stoermer-Verlet method. The behavior of the methods is illustrated on two effectively 1+1-dimensional versions of Einstein's equations, that allow to investigate a perturbed Minkowski problem and the Schwarzschild space-time. We compare symplectic and non-symplectic integrators for free evolution, showing very different numerical behavior for nearly-conserved quantities in the perturbed Minkowski problem. Further we compare free and constrained evolution, demonstrating in our examples that enforcing the momentum constraints can turn an unstable free evolution into a stable constrained evolution. This is demonstrated in the stabilization of a perturbed Minkowski problem with Dirac gauge, and in the suppression of the propagation of boundary instabilities into the interior of the domain in Schwarzschild space-time. |
gr-qc/0109032 | Hwei-Jang Yo | H.J. Yo, T.W. Baumgarte and S.L. Shapiro | A numerical testbed for singularity excision in moving black hole
spacetimes | 13 pages, 6 figures, to be published in PRD | Phys.Rev. D64 (2001) 124011 | 10.1103/PhysRevD.64.124011 | null | gr-qc astro-ph | null | We evolve a scalar field in a fixed Kerr-Schild background geometry to test
simple $(3+1)$-dimensional algorithms for singularity excision. We compare both
centered and upwind schemes for handling the shift (advection) terms, as well
as different approaches for implementing the excision boundary conditions, for
both static and boosted black holes. By first determining the scalar field
evolution in a static frame with a $(1+1)$-dimensional code, we obtain the
solution to very high precision. This solution then provides a useful testbed
for simulations in full $(3+1)$ dimensions. We show that some algorithms which
are stable for non-boosted black holes become unstable when the boost velocity
becomes high.
| [
{
"created": "Mon, 10 Sep 2001 20:18:55 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Yo",
"H. J.",
""
],
[
"Baumgarte",
"T. W.",
""
],
[
"Shapiro",
"S. L.",
""
]
] | We evolve a scalar field in a fixed Kerr-Schild background geometry to test simple $(3+1)$-dimensional algorithms for singularity excision. We compare both centered and upwind schemes for handling the shift (advection) terms, as well as different approaches for implementing the excision boundary conditions, for both static and boosted black holes. By first determining the scalar field evolution in a static frame with a $(1+1)$-dimensional code, we obtain the solution to very high precision. This solution then provides a useful testbed for simulations in full $(3+1)$ dimensions. We show that some algorithms which are stable for non-boosted black holes become unstable when the boost velocity becomes high. |
2401.16297 | Leonardo Garc\'ia-Heveling | Leonardo Garc\'ia-Heveling | Radial Gravitational Collapse Causes Timelike Incompleteness | Slightly updated exposition, 5 pages | Phys. Rev. D 109 (2024) 8, 084034 | 10.1103/PhysRevD.109.084034 | null | gr-qc math-ph math.DG math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that a globally hyperbolic spacetime containing a trapped surface and
satisfying the strong energy condition and a condition on certain radial tidal
forces must be timelike geodesically incomplete. This constitutes a "timelike"
version of Penrose's celebrated singularity theorem. Recall that the latter
concludes that certain spacetimes are null incomplete, providing the first
theoretical evidence that black holes actually exist in our Universe. By
concluding timelike instead of null incompleteness, we obtain, at the expense
of stronger assumptions, a clearer physical interpretation and the existence of
an event horizon.
| [
{
"created": "Mon, 29 Jan 2024 16:57:48 GMT",
"version": "v1"
},
{
"created": "Mon, 6 May 2024 14:45:08 GMT",
"version": "v2"
}
] | 2024-05-07 | [
[
"García-Heveling",
"Leonardo",
""
]
] | We show that a globally hyperbolic spacetime containing a trapped surface and satisfying the strong energy condition and a condition on certain radial tidal forces must be timelike geodesically incomplete. This constitutes a "timelike" version of Penrose's celebrated singularity theorem. Recall that the latter concludes that certain spacetimes are null incomplete, providing the first theoretical evidence that black holes actually exist in our Universe. By concluding timelike instead of null incompleteness, we obtain, at the expense of stronger assumptions, a clearer physical interpretation and the existence of an event horizon. |
gr-qc/0512093 | Lee Lindblom | Lee Lindblom, Mark A. Scheel, Lawrence E. Kidder, Robert Owen, and
Oliver Rinne | A New Generalized Harmonic Evolution System | Updated to agree with published version | Class.Quant.Grav.23:S447-S462,2006 | 10.1088/0264-9381/23/16/S09 | null | gr-qc | null | A new representation of the Einstein evolution equations is presented that is
first order, linearly degenerate, and symmetric hyperbolic. This new system
uses the generalized harmonic method to specify the coordinates, and
exponentially suppresses all small short-wavelength constraint violations.
Physical and constraint-preserving boundary conditions are derived for this
system, and numerical tests that demonstrate the effectiveness of the
constraint suppression properties and the constraint-preserving boundary
conditions are presented.
| [
{
"created": "Thu, 15 Dec 2005 18:09:47 GMT",
"version": "v1"
},
{
"created": "Fri, 6 Jan 2006 23:34:10 GMT",
"version": "v2"
},
{
"created": "Tue, 4 Dec 2007 16:50:44 GMT",
"version": "v3"
}
] | 2011-04-21 | [
[
"Lindblom",
"Lee",
""
],
[
"Scheel",
"Mark A.",
""
],
[
"Kidder",
"Lawrence E.",
""
],
[
"Owen",
"Robert",
""
],
[
"Rinne",
"Oliver",
""
]
] | A new representation of the Einstein evolution equations is presented that is first order, linearly degenerate, and symmetric hyperbolic. This new system uses the generalized harmonic method to specify the coordinates, and exponentially suppresses all small short-wavelength constraint violations. Physical and constraint-preserving boundary conditions are derived for this system, and numerical tests that demonstrate the effectiveness of the constraint suppression properties and the constraint-preserving boundary conditions are presented. |
1706.01630 | Jing-Bo Wang | Jingbo Wang | Black hole as topological insulator (II): the boundary modes | 6 pages, adding canonical mass dimension analysis | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the previous paper Ref.[1], it was claimed that the black hole can be
considered as a kind of topological insulator. For BTZ black hole in three
dimensional $AdS_3$ spacetime two evidences were given to support this claim:
the first evidence comes from the black hole "membrane paradigm", and the
second evidence comes from the fact that the horizon of BTZ black hole can
support two chiral massless scalar field with opposite chirality. Those are two
key properties of 2D topological insulator. For higher dimensional black hole
the first evidence is still valid but the second fails. In this paper, starting
from the boundary BF theory, which can be used to describe the boundary degrees
of freedom of black hole in arbitrary dimension, we shown that the isolated
horizon of $3+1-$D black hole can support massless scalar field and vector
field. Those two fields can be used to construct a massless Dirac field through
the $2+1-$dimensional bosonization, which also appears on the boundary of
$3+1-$D topological insulators.
| [
{
"created": "Tue, 6 Jun 2017 07:12:11 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Dec 2017 01:52:33 GMT",
"version": "v2"
}
] | 2017-12-21 | [
[
"Wang",
"Jingbo",
""
]
] | In the previous paper Ref.[1], it was claimed that the black hole can be considered as a kind of topological insulator. For BTZ black hole in three dimensional $AdS_3$ spacetime two evidences were given to support this claim: the first evidence comes from the black hole "membrane paradigm", and the second evidence comes from the fact that the horizon of BTZ black hole can support two chiral massless scalar field with opposite chirality. Those are two key properties of 2D topological insulator. For higher dimensional black hole the first evidence is still valid but the second fails. In this paper, starting from the boundary BF theory, which can be used to describe the boundary degrees of freedom of black hole in arbitrary dimension, we shown that the isolated horizon of $3+1-$D black hole can support massless scalar field and vector field. Those two fields can be used to construct a massless Dirac field through the $2+1-$dimensional bosonization, which also appears on the boundary of $3+1-$D topological insulators. |
gr-qc/0603132 | Robert Steven Millward | R. Steven Millward | A five-dimensional Schwarzschild-like solution | RevTex, 5 pages, no figures | null | null | null | gr-qc hep-th | null | In recent years, interest in extra dimensions has experienced a dramatic
increase. A common practice has been to look for higher-dimensional
generalizations of four-dimensional solutions to the Einstein equations. In
this vein, we have found a static, spherically symmetric solution to the 5-d
Einstein equations. Certain aspects of this solution are very different from
the 4-d Schwarzschild solution. However, in observationally accessible regions,
the geodesics of the two solutions are essentially the same.
| [
{
"created": "Fri, 31 Mar 2006 18:48:16 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Millward",
"R. Steven",
""
]
] | In recent years, interest in extra dimensions has experienced a dramatic increase. A common practice has been to look for higher-dimensional generalizations of four-dimensional solutions to the Einstein equations. In this vein, we have found a static, spherically symmetric solution to the 5-d Einstein equations. Certain aspects of this solution are very different from the 4-d Schwarzschild solution. However, in observationally accessible regions, the geodesics of the two solutions are essentially the same. |
2303.03159 | Gamal G.L. Nashed | G. G. L. Nashed and S. Capozziello | Spinning (A)dS Black Holes with Slow-Rotation Approximation in Dynamical
Chern-Simons Modified Gravity | 15 pages 3 figures, will appear in Phys. Rev D | null | 10.1103/PhysRevD.107.063008 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | One of the most crucial areas of gravity research, after the direct
observation of gravitational waves, is the possible modification of General
Relativity at ultraviolet and infrared scales. In particular, the possibility
of parity violation should be considered in strong field regime. The
Chern-Simons gravity takes into account parity violation in strong gravity
regime. For all conformally flat spacetimes and spacetimes with a maximally
symmetric two-dimensional subspace, Chern-Simons gravity is identical to
General Relativity. Specifically, the Anti-de Sitter (A)dS-Kerr/Kerr black hole
is not a solution for Chern-Simons gravity. The slow-rotating BH and the
quadratic order in spin solutions are some of the known solutions to quadratic
order in spin and they are rotating solutions in the frame of dynamical
Chern-Simons gravity.
In the present study, for the (A)dS slow-rotating situation (correct to the
first order in spin), we derive the linear perturbation equations controlling
the metric and the dynamical Chern-Simons field equation corrected to the
linear order in spin and to the second order in the Chern-Simons coupling
parameter. We show that the black hole of the (A)dS-Kerr solution is stronger
(i.e. more compact and energetic) than the Kerr black hole solution and the
reason for this feature comes form contributions at Planck scales. Moreover, we
calculate the thermodynamical quantities related to this black hole. Finally,
we calculate the geodesic equation and derive the effective potential of the
black hole.
| [
{
"created": "Thu, 2 Mar 2023 07:47:00 GMT",
"version": "v1"
}
] | 2023-03-29 | [
[
"Nashed",
"G. G. L.",
""
],
[
"Capozziello",
"S.",
""
]
] | One of the most crucial areas of gravity research, after the direct observation of gravitational waves, is the possible modification of General Relativity at ultraviolet and infrared scales. In particular, the possibility of parity violation should be considered in strong field regime. The Chern-Simons gravity takes into account parity violation in strong gravity regime. For all conformally flat spacetimes and spacetimes with a maximally symmetric two-dimensional subspace, Chern-Simons gravity is identical to General Relativity. Specifically, the Anti-de Sitter (A)dS-Kerr/Kerr black hole is not a solution for Chern-Simons gravity. The slow-rotating BH and the quadratic order in spin solutions are some of the known solutions to quadratic order in spin and they are rotating solutions in the frame of dynamical Chern-Simons gravity. In the present study, for the (A)dS slow-rotating situation (correct to the first order in spin), we derive the linear perturbation equations controlling the metric and the dynamical Chern-Simons field equation corrected to the linear order in spin and to the second order in the Chern-Simons coupling parameter. We show that the black hole of the (A)dS-Kerr solution is stronger (i.e. more compact and energetic) than the Kerr black hole solution and the reason for this feature comes form contributions at Planck scales. Moreover, we calculate the thermodynamical quantities related to this black hole. Finally, we calculate the geodesic equation and derive the effective potential of the black hole. |
0712.4064 | Piotr T. Chru\'sciel | Piotr T. Chru\'sciel, Yanyan Li and Gilbert Weinstein | Mass and angular-momentum inequalities for axi-symmetric initial data
sets. II. Angular-momentum | added Appendix C on uniqueness | AnnalsPhys.323:2591-2613,2008 | 10.1016/j.aop.2007.12.011 | null | gr-qc | null | We extend the validity of Dain's angular-momentum inequality to maximal,
asymptotically flat, initial data sets on a simply connected manifold with
several asymptotically flat ends which are invariant under a U(1) action and
which admit a twist potential.
| [
{
"created": "Wed, 26 Dec 2007 16:29:32 GMT",
"version": "v1"
},
{
"created": "Fri, 30 May 2008 19:53:50 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Chruściel",
"Piotr T.",
""
],
[
"Li",
"Yanyan",
""
],
[
"Weinstein",
"Gilbert",
""
]
] | We extend the validity of Dain's angular-momentum inequality to maximal, asymptotically flat, initial data sets on a simply connected manifold with several asymptotically flat ends which are invariant under a U(1) action and which admit a twist potential. |
gr-qc/0411037 | Robin W. Tucker | David A. Burton, Adam Noble, Robin W. Tucker, David L. Wiltshire | Twisted Electromagnetic Modes and Sagnac Ring-Lasers | LaTeX 31 pages, 3 Figures | Class.Quant.Grav. 22 (2005) 909-931 | 10.1088/0264-9381/22/6/001 | Lancaster 8-11-2004 | gr-qc | null | A new approximation scheme, designed to solve the covariant Maxwell equations
inside a rotating hollow slender conducting cavity (modelling a ring-laser), is
constructed. It is shown that for well-defined conditions there exist TE and TM
modes with respect to the longitudinal axis of the cavity. A twisted mode
spectrum is found to depend on the integrated Frenet torsion of the cavity and
this in turn may affect the Sagnac beat frequency induced by a non-zero
rotation of the cavity. The analysis is motivated by attempts to use
ring-lasers to measure terrestrial gravito-magnetism or the Lense-Thirring
effect produced by the rotation of the Earth.
| [
{
"created": "Mon, 8 Nov 2004 16:55:25 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Burton",
"David A.",
""
],
[
"Noble",
"Adam",
""
],
[
"Tucker",
"Robin W.",
""
],
[
"Wiltshire",
"David L.",
""
]
] | A new approximation scheme, designed to solve the covariant Maxwell equations inside a rotating hollow slender conducting cavity (modelling a ring-laser), is constructed. It is shown that for well-defined conditions there exist TE and TM modes with respect to the longitudinal axis of the cavity. A twisted mode spectrum is found to depend on the integrated Frenet torsion of the cavity and this in turn may affect the Sagnac beat frequency induced by a non-zero rotation of the cavity. The analysis is motivated by attempts to use ring-lasers to measure terrestrial gravito-magnetism or the Lense-Thirring effect produced by the rotation of the Earth. |
gr-qc/0005021 | Georges F. Bressange | Georges F. Bressange | On the extension of the concept of Thin Shells to The Einstein-Cartan
Theory | Latex, 21 pages, 1 combined Latex/Postscript figure; Accepted for
publication in Classical and Quantum Gravity | Class.Quant.Grav. 17 (2000) 2509-2524 | 10.1088/0264-9381/17/13/304 | null | gr-qc | null | This paper develops a theory of thin shells within the context of the
Einstein-Cartan theory by extending the known formalism of general relativity.
In order to perform such an extension, we require the general non symmetric
stress-energy tensor to be conserved leading, as Cartan pointed out himself, to
a strong constraint relating curvature and torsion of spacetime. When we
restrict ourselves to the class of space-times satisfying this constraint, we
are able to properly describe thin shells and derive the general expression of
surface stress-energy tensor both in its four-dimensional and in its
three-dimensional intrinsic form. We finally derive a general family of static
solutions of the Einstein-Cartan theory exhibiting a natural family of null
hypersurfaces and use it to apply our formalism to the construction of a null
shell of matter.
| [
{
"created": "Mon, 8 May 2000 11:32:59 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Bressange",
"Georges F.",
""
]
] | This paper develops a theory of thin shells within the context of the Einstein-Cartan theory by extending the known formalism of general relativity. In order to perform such an extension, we require the general non symmetric stress-energy tensor to be conserved leading, as Cartan pointed out himself, to a strong constraint relating curvature and torsion of spacetime. When we restrict ourselves to the class of space-times satisfying this constraint, we are able to properly describe thin shells and derive the general expression of surface stress-energy tensor both in its four-dimensional and in its three-dimensional intrinsic form. We finally derive a general family of static solutions of the Einstein-Cartan theory exhibiting a natural family of null hypersurfaces and use it to apply our formalism to the construction of a null shell of matter. |
1110.3297 | Vladimir Dergachev Ph.D. | Vladimir Dergachev | Loosely coherent searches for sets of well-modeled signals | null | null | 10.1103/PhysRevD.85.062003 | LIGO-P1100104-v6 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We introduce a high-performance implementation of a loosely coherent
statistic sensitive to signals spanning a finite-dimensional manifold in
parameter space. Results from full scale simulations on Gaussian noise are
discussed, as well as implications for future searches for continuous
gravitational waves. We demonstrate an improvement of more than an order of
magnitude in analysis speed over previously available algorithms. As searches
for continuous gravitational waves are computationally limited, the large
speedup results in gain in sensitivity.
| [
{
"created": "Fri, 14 Oct 2011 18:50:06 GMT",
"version": "v1"
}
] | 2013-05-30 | [
[
"Dergachev",
"Vladimir",
""
]
] | We introduce a high-performance implementation of a loosely coherent statistic sensitive to signals spanning a finite-dimensional manifold in parameter space. Results from full scale simulations on Gaussian noise are discussed, as well as implications for future searches for continuous gravitational waves. We demonstrate an improvement of more than an order of magnitude in analysis speed over previously available algorithms. As searches for continuous gravitational waves are computationally limited, the large speedup results in gain in sensitivity. |
1804.02650 | Jie-Xiong Mo | Jie-Xiong Mo, Gu-Qiang Li, Shan-Quan Lan and Xiao-Bao Xu | Joule-Thomson expansion of $d$-dimensional charged AdS black holes | Comments welcome. 11pages, 5figures | Phys. Rev. D 98, 124032 (2018) | 10.1103/PhysRevD.98.124032 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Effects of the dimensionality on the Joule-Thomson expansion are discussed in
detail by considering the case of $d$-dimensional charged AdS black holes.
Specifically, we investigate three important aspects characteristic of the
Joule-Thomson expansion. Namely, the Joule-Thomson coefficient, the inversion
curves and the isenthalpic curves. We utilize two different approaches to
derive the explicit expression of the Joule-Thomson coefficient and show that
both approaches are consistent with each other. The divergent point and the
zero point of the Joule-Thomson coefficient are discussed. The former is shown
to reveal the information of Hawking temperature while the latter is depicted
through the so-called inversion curves. Fine structures of the inversion curves
are disclosed in the cases $d>4$. At low pressure, the inversion temperature
increases with the dimensionality $d$ while at high pressure it decreases with
$d$. The ratio between minimum inversion temperature $T_{min}$ and the critical
temperature $T_c$ is discussed with its explicit expression obtained for $d>4$.
Surprisingly, it is shown that the ratio is not always equal to $1/2$ but
decreases with the dimensionality $d$. Moreover, isenthalpic curves of $d>4$
are shown to expand toward higher pressure when the dimensionality $d$
increases.
| [
{
"created": "Sun, 8 Apr 2018 08:38:00 GMT",
"version": "v1"
}
] | 2018-12-26 | [
[
"Mo",
"Jie-Xiong",
""
],
[
"Li",
"Gu-Qiang",
""
],
[
"Lan",
"Shan-Quan",
""
],
[
"Xu",
"Xiao-Bao",
""
]
] | Effects of the dimensionality on the Joule-Thomson expansion are discussed in detail by considering the case of $d$-dimensional charged AdS black holes. Specifically, we investigate three important aspects characteristic of the Joule-Thomson expansion. Namely, the Joule-Thomson coefficient, the inversion curves and the isenthalpic curves. We utilize two different approaches to derive the explicit expression of the Joule-Thomson coefficient and show that both approaches are consistent with each other. The divergent point and the zero point of the Joule-Thomson coefficient are discussed. The former is shown to reveal the information of Hawking temperature while the latter is depicted through the so-called inversion curves. Fine structures of the inversion curves are disclosed in the cases $d>4$. At low pressure, the inversion temperature increases with the dimensionality $d$ while at high pressure it decreases with $d$. The ratio between minimum inversion temperature $T_{min}$ and the critical temperature $T_c$ is discussed with its explicit expression obtained for $d>4$. Surprisingly, it is shown that the ratio is not always equal to $1/2$ but decreases with the dimensionality $d$. Moreover, isenthalpic curves of $d>4$ are shown to expand toward higher pressure when the dimensionality $d$ increases. |
gr-qc/9407001 | Peter Goetsch Phy103 | Peter Goetsch, Robert Graham, Fritz Haake | Cat States and Single Runs for the Damped Harmonic Oscillator | 18, Revtex | null | 10.1103/PhysRevA.51.136 | null | gr-qc | null | We discuss the fate of initial states of the cat type for the damped harmonic
oscillator, mostly employing a linear version of the stochastic Schr\"odinger
equation. We also comment on how such cat states might be prepared and on the
relation of single realizations of the noise to single runs of experiments.
| [
{
"created": "Mon, 4 Jul 1994 11:04:58 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Goetsch",
"Peter",
""
],
[
"Graham",
"Robert",
""
],
[
"Haake",
"Fritz",
""
]
] | We discuss the fate of initial states of the cat type for the damped harmonic oscillator, mostly employing a linear version of the stochastic Schr\"odinger equation. We also comment on how such cat states might be prepared and on the relation of single realizations of the noise to single runs of experiments. |
gr-qc/0605052 | Stephen P. Boughn | Stephen Boughn, Tony Rothman | Aspects of Graviton Detection: Graviton Emission and Absorption by
Atomic Hydrogen | 19 pages, no figures | Class.Quant.Grav. 23 (2006) 5839-5852 | 10.1088/0264-9381/23/20/006 | null | gr-qc astro-ph quant-ph | null | Graviton absorption cross sections and emission rates for hydrogen are
calculated by both semi-classical and field theoretic methods. We point out
several mistakes in the literature concerning spontaneous emission of gravitons
and related phenomena, some of which are due to a subtle issue concerning gauge
invariance of the linearized interaction Hamiltonian.
| [
{
"created": "Tue, 9 May 2006 18:02:24 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Sep 2006 12:24:03 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Boughn",
"Stephen",
""
],
[
"Rothman",
"Tony",
""
]
] | Graviton absorption cross sections and emission rates for hydrogen are calculated by both semi-classical and field theoretic methods. We point out several mistakes in the literature concerning spontaneous emission of gravitons and related phenomena, some of which are due to a subtle issue concerning gauge invariance of the linearized interaction Hamiltonian. |
1407.6727 | Helvi Witek | T\'erence Delsate, David Hilditch and Helvi Witek | The Initial Value Formulation of Dynamical Chern-Simons Gravity | 16 pages; matches published version | Phys. Rev. D 91, 024027, 2015 | 10.1103/PhysRevD.91.024027 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive an initial value formulation for dynamical Chern-Simons gravity, a
modification of general relativity involving parity-violating higher derivative
terms. We investigate the structure of the resulting system of partial
differential equations thinking about linearization around arbitrary
backgrounds. This type of consideration is necessary if we are to establish
well-posedness of the Cauchy problem. Treating the field equations as an
effective field theory we find that weak necessary conditions for hyperbolicity
are satisfied. For the full field equations we find that there are states from
which subsequent evolution is not determined. Generically the evolution system
closes, but the full field equations are in no sense hyperbolic. In a cursory
mode analysis we find that the equations of motion contain terms that may cause
ill-posedness of the initial value problem.
| [
{
"created": "Thu, 24 Jul 2014 20:22:27 GMT",
"version": "v1"
},
{
"created": "Thu, 22 Jan 2015 19:19:02 GMT",
"version": "v2"
}
] | 2015-06-22 | [
[
"Delsate",
"Térence",
""
],
[
"Hilditch",
"David",
""
],
[
"Witek",
"Helvi",
""
]
] | We derive an initial value formulation for dynamical Chern-Simons gravity, a modification of general relativity involving parity-violating higher derivative terms. We investigate the structure of the resulting system of partial differential equations thinking about linearization around arbitrary backgrounds. This type of consideration is necessary if we are to establish well-posedness of the Cauchy problem. Treating the field equations as an effective field theory we find that weak necessary conditions for hyperbolicity are satisfied. For the full field equations we find that there are states from which subsequent evolution is not determined. Generically the evolution system closes, but the full field equations are in no sense hyperbolic. In a cursory mode analysis we find that the equations of motion contain terms that may cause ill-posedness of the initial value problem. |
gr-qc/0010046 | Julio Cesar Fabris | J.C. Fabris and S.V.B. Goncalves (Universidade Federal do Espirito
Santo, Brazil) | Evolution of perturbations in a domain wall cosmology | Latex file, 8 pages | Braz.J.Phys. 33 (2003) 834-839 | null | null | gr-qc astro-ph | null | A fluid of domain walls has an effective equation of state $p_w = -
{2/3}\rho_w$. This equation of state is qualitativelly in agreement with the
supernova type Ia observations. We exploit a cosmological model where the
matter content is given by a dust fluid and a domain wall fluid. The process of
formation of galaxies is essentially preserved. On the other hand, the
behaviour of the density contrast in the ordinary fluid is highly altered when
domain walls begin to dominate the matter content of the Universe. This domain
wall phase occurs at relative recent era, and its possible consequences are
discussed, specially concerning the Sachs-Wolfe effect.
| [
{
"created": "Wed, 11 Oct 2000 20:53:01 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Fabris",
"J. C.",
"",
"Universidade Federal do Espirito\n Santo, Brazil"
],
[
"Goncalves",
"S. V. B.",
"",
"Universidade Federal do Espirito\n Santo, Brazil"
]
] | A fluid of domain walls has an effective equation of state $p_w = - {2/3}\rho_w$. This equation of state is qualitativelly in agreement with the supernova type Ia observations. We exploit a cosmological model where the matter content is given by a dust fluid and a domain wall fluid. The process of formation of galaxies is essentially preserved. On the other hand, the behaviour of the density contrast in the ordinary fluid is highly altered when domain walls begin to dominate the matter content of the Universe. This domain wall phase occurs at relative recent era, and its possible consequences are discussed, specially concerning the Sachs-Wolfe effect. |
gr-qc/9801084 | Yasuo Ezawa | Yasuo Ezawa, Masahiko Kiminami, Masahiro Kajihara(Ehine University),
Jiro Soda(Kyoto University) and Tadasi Yano(Ehime University) | On the Canonical Formalism for a Higher-Curvature Gravity | 11 pages, no figures, Latex file | Class.Quant.Grav. 16 (1999) 1127-1135 | 10.1088/0264-9381/16/4/003 | null | gr-qc | null | Following the method of Buchbinder and Lyahovich, we carry out a canonical
formalism for a higher-curvature gravity in which the Lagrangian density ${\cal
L}$ is given in terms of a function of the salar curvature $R$ as ${\cal
L}=\sqrt{-\det g_{\mu\nu}}f(R)$. The local Hamiltonian is obtained by a
canonical transformation which interchanges a pair of the generalized
coordinate and its canonical momentum coming from the higher derivative of the
metric.
| [
{
"created": "Mon, 26 Jan 1998 06:55:41 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Ezawa",
"Yasuo",
"",
"Ehine University"
],
[
"Kiminami",
"Masahiko",
"",
"Ehine University"
],
[
"Kajihara",
"Masahiro",
"",
"Ehine University"
],
[
"Soda",
"Jiro",
"",
"Kyoto University"
],
[
"Yano",
"Tadasi",
"",
"E... | Following the method of Buchbinder and Lyahovich, we carry out a canonical formalism for a higher-curvature gravity in which the Lagrangian density ${\cal L}$ is given in terms of a function of the salar curvature $R$ as ${\cal L}=\sqrt{-\det g_{\mu\nu}}f(R)$. The local Hamiltonian is obtained by a canonical transformation which interchanges a pair of the generalized coordinate and its canonical momentum coming from the higher derivative of the metric. |
gr-qc/9909064 | N. K. Dadhich | Naresh Dadhich, L.K. Patel and R. Tikekar | Global monopole as dual-vacuum solution in Kaluza-Klein spacetime | 8 pages, LaTEX version | Mod.Phys.Lett. A14 (1999) 2721-2726 | 10.1142/S0217732399002868 | IUCAA-34/99 | gr-qc | null | By application of the duality transformation, which implies interchange of
active and passive electric parts of the Riemann curvature (equivalent to
interchange of Ricci and Einstein tensors) it is shown that the global monopole
solution in the Kaluza-Klein spacetime is dual to the corresponding vacuum
solution. Further we also obtain solution dual to flat space which would in
general describe a massive global monopole in 4-dimensional Euclidean space and
would have massless limit analogus to the 4-dimensional dual-flat solution.
| [
{
"created": "Tue, 21 Sep 1999 12:04:51 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Dadhich",
"Naresh",
""
],
[
"Patel",
"L. K.",
""
],
[
"Tikekar",
"R.",
""
]
] | By application of the duality transformation, which implies interchange of active and passive electric parts of the Riemann curvature (equivalent to interchange of Ricci and Einstein tensors) it is shown that the global monopole solution in the Kaluza-Klein spacetime is dual to the corresponding vacuum solution. Further we also obtain solution dual to flat space which would in general describe a massive global monopole in 4-dimensional Euclidean space and would have massless limit analogus to the 4-dimensional dual-flat solution. |
0805.2480 | Francesco Cianfrani dr | F. Cianfrani, G. Montani | Curvature-spin coupling from the semi-classical limit of the Dirac
equation | 4 pages, Proceedings of the II Stueckelberg workshop | Int.J.Mod.Phys.A23:1274-1277,2008 | 10.1142/S0217751X08040214 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The notion of a classical particle is inferred from Dirac quantum fields on a
curved space-time, by an eikonal approximation and a localization hypothesis
for amplitudes. This procedure allows to define a semi-classical version of the
spin-tensor from internal quantum degrees of freedom, which has a
Papapetrou-like coupling with the curvature.
| [
{
"created": "Fri, 16 May 2008 09:08:52 GMT",
"version": "v1"
}
] | 2014-11-18 | [
[
"Cianfrani",
"F.",
""
],
[
"Montani",
"G.",
""
]
] | The notion of a classical particle is inferred from Dirac quantum fields on a curved space-time, by an eikonal approximation and a localization hypothesis for amplitudes. This procedure allows to define a semi-classical version of the spin-tensor from internal quantum degrees of freedom, which has a Papapetrou-like coupling with the curvature. |
2306.03148 | Jooheon Yoo | Jooheon Yoo, Keefe Mitman, Vijay Varma, Michael Boyle, Scott E. Field,
Nils Deppe, Fran\c{c}ois H\'ebert, Lawrence E. Kidder, Jordan Moxon, Harald
P. Pfeiffer, Mark A. Scheel, Leo C. Stein, Saul A. Teukolsky, William Throwe,
and Nils L. Vu | Numerical relativity surrogate model with memory effects and
post-Newtonian hybridization | 14 pages, 11 figures. Accepted for publication in PRD | Phys. Rev. D 108, 064027 (2023) | 10.1103/PhysRevD.108.064027 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Numerical relativity simulations provide the most precise templates for the
gravitational waves produced by binary black hole mergers. However, many of
these simulations use an incomplete waveform extraction technique --
extrapolation -- that fails to capture important physics, such as gravitational
memory effects. Cauchy-characteristic evolution (CCE), by contrast, is a much
more physically accurate extraction procedure that fully evolves Einstein's
equations to future null infinity and accurately captures the expected physics.
In this work, we present a new surrogate model, NRHybSur3dq8$\_$CCE, built from
CCE waveforms that have been mapped to the post-Newtonian (PN) BMS frame and
then hybridized with PN and effective one-body (EOB) waveforms. This model is
trained on 102 waveforms with mass ratios $q\leq8$ and aligned spins
$\chi_{1z}, \, \chi_{2z} \in \left[-0.8, 0.8\right]$. The model spans the
entire LIGO-Virgo-KAGRA (LVK) frequency band (with
$f_{\text{low}}=20\text{Hz}$) for total masses $M\gtrsim2.25M_{\odot}$ and
includes the $\ell\leq4$ and $(\ell,m)=(5,5)$ spin-weight $-2$ spherical
harmonic modes, but not the $(3,1)$, $(4,2)$ or $(4,1)$ modes. We find that
NRHybSur3dq8$\_$CCE can accurately reproduce the training waveforms with
mismatches $\lesssim2\times10^{-4}$ for total masses $2.25M_{\odot}\leq
M\leq300M_{\odot}$ and can, for a modest degree of extrapolation, capably model
outside of its training region. Most importantly, unlike previous waveform
models, the new surrogate model successfully captures memory effects.
| [
{
"created": "Mon, 5 Jun 2023 18:01:55 GMT",
"version": "v1"
},
{
"created": "Thu, 14 Sep 2023 15:17:32 GMT",
"version": "v2"
}
] | 2024-01-02 | [
[
"Yoo",
"Jooheon",
""
],
[
"Mitman",
"Keefe",
""
],
[
"Varma",
"Vijay",
""
],
[
"Boyle",
"Michael",
""
],
[
"Field",
"Scott E.",
""
],
[
"Deppe",
"Nils",
""
],
[
"Hébert",
"François",
""
],
[
"Kidder... | Numerical relativity simulations provide the most precise templates for the gravitational waves produced by binary black hole mergers. However, many of these simulations use an incomplete waveform extraction technique -- extrapolation -- that fails to capture important physics, such as gravitational memory effects. Cauchy-characteristic evolution (CCE), by contrast, is a much more physically accurate extraction procedure that fully evolves Einstein's equations to future null infinity and accurately captures the expected physics. In this work, we present a new surrogate model, NRHybSur3dq8$\_$CCE, built from CCE waveforms that have been mapped to the post-Newtonian (PN) BMS frame and then hybridized with PN and effective one-body (EOB) waveforms. This model is trained on 102 waveforms with mass ratios $q\leq8$ and aligned spins $\chi_{1z}, \, \chi_{2z} \in \left[-0.8, 0.8\right]$. The model spans the entire LIGO-Virgo-KAGRA (LVK) frequency band (with $f_{\text{low}}=20\text{Hz}$) for total masses $M\gtrsim2.25M_{\odot}$ and includes the $\ell\leq4$ and $(\ell,m)=(5,5)$ spin-weight $-2$ spherical harmonic modes, but not the $(3,1)$, $(4,2)$ or $(4,1)$ modes. We find that NRHybSur3dq8$\_$CCE can accurately reproduce the training waveforms with mismatches $\lesssim2\times10^{-4}$ for total masses $2.25M_{\odot}\leq M\leq300M_{\odot}$ and can, for a modest degree of extrapolation, capably model outside of its training region. Most importantly, unlike previous waveform models, the new surrogate model successfully captures memory effects. |
1906.02879 | Daniele Gregoris | Daniele Gregoris, Yen Chin Ong, and Bin Wang | Holographic Principle and the Second Law in Stephani Cosmology Revisited | 14 pages, 3 figures. This manuscript revisits arXiv:1712.02297.
Matches pulished version | Eur. Phys. J. Plus 135, 246 (2020) | 10.1140/epjp/s13360-020-00249-3 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show in a model-independent way that the inhomogeneous cosmological class
II Stephani model fulfills both the the cosmological holographic principle, and
that the entropy is increasing with time. By this we mean the result does not
depend on any assumption on the time evolution of the scale factor, or on the
matter content of the Universe, we also do not need to use the numerical values
of the cosmological parameters, which are inferred in the framework of the
usual homogeneous Friedmann model. Therefore our analysis is not affected by
the tension of the current estimates of the Hubble parameter, and does not rely
on any model-dependent assumption of the entropy amount at the present epoch.
Our analysis allows us to set an upper limit for the inhomogeneity parameter of
the model, an upper bound for the size that this type of universe can reach
during the time evolution, a lower bound for the entropy abundance, and an
estimate of the present day value of the deceleration parameter.
| [
{
"created": "Fri, 7 Jun 2019 03:14:54 GMT",
"version": "v1"
},
{
"created": "Mon, 24 Feb 2020 14:19:00 GMT",
"version": "v2"
}
] | 2020-02-25 | [
[
"Gregoris",
"Daniele",
""
],
[
"Ong",
"Yen Chin",
""
],
[
"Wang",
"Bin",
""
]
] | We show in a model-independent way that the inhomogeneous cosmological class II Stephani model fulfills both the the cosmological holographic principle, and that the entropy is increasing with time. By this we mean the result does not depend on any assumption on the time evolution of the scale factor, or on the matter content of the Universe, we also do not need to use the numerical values of the cosmological parameters, which are inferred in the framework of the usual homogeneous Friedmann model. Therefore our analysis is not affected by the tension of the current estimates of the Hubble parameter, and does not rely on any model-dependent assumption of the entropy amount at the present epoch. Our analysis allows us to set an upper limit for the inhomogeneity parameter of the model, an upper bound for the size that this type of universe can reach during the time evolution, a lower bound for the entropy abundance, and an estimate of the present day value of the deceleration parameter. |
2308.14875 | Leonardo Balart | Leonardo Balart, Sharmanthie Fernando | Thermodynamics and the Joule-Thomson expansion of dilaton black holes in
2+1 dimensions | 31 pages, 24 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | In this paper, we study thermodynamics and its applications to the static
charged dilaton black hole in 2+1 dimensions. We chose the extended phase space
where the pressure $P = -\frac{\Lambda}{ 8 \pi}$. There is a number $N$ for the
black hole solutions which leads to a class of black holes where $ \frac{2}{3}
\leq N < 2$. We noticed that thermodynamic behavior falls into two broad
categories: For $\frac{2}{3} \leq N < 1$, the black hole is locally stable for
all values of the horizon radius and does not go through phase transitions. For
$ 1 \leq N < 2$, small black holes are locally stable and large black holes are
not: there is a first order phase transition between small black holes and the
thermal AdS space similar to Hawking-Page phase transition. In order to
demonstrate the two broad categories, we have focused on $N =1, \frac{2}{3}$
and $N = \frac{6}{7}$ black holes in detail. We computed the first law and the
Smarr relations for the black hole and introduced two new thermodynamical
parameters in order to satisfy the first law. We computed specific heat
capacities, internal energy and free energy for black holes and studied local
and global stability of the black hole. We have also studied the Joule-Thomson
expansion for the black hole. It is also noted that unlike the charged BTZ
black hole, the charged dilaton black hole does not violate the Reverse
Isoperimetric Inequality for certain values of parameters of the theory.
| [
{
"created": "Mon, 28 Aug 2023 19:59:32 GMT",
"version": "v1"
},
{
"created": "Thu, 8 Aug 2024 02:11:00 GMT",
"version": "v2"
}
] | 2024-08-09 | [
[
"Balart",
"Leonardo",
""
],
[
"Fernando",
"Sharmanthie",
""
]
] | In this paper, we study thermodynamics and its applications to the static charged dilaton black hole in 2+1 dimensions. We chose the extended phase space where the pressure $P = -\frac{\Lambda}{ 8 \pi}$. There is a number $N$ for the black hole solutions which leads to a class of black holes where $ \frac{2}{3} \leq N < 2$. We noticed that thermodynamic behavior falls into two broad categories: For $\frac{2}{3} \leq N < 1$, the black hole is locally stable for all values of the horizon radius and does not go through phase transitions. For $ 1 \leq N < 2$, small black holes are locally stable and large black holes are not: there is a first order phase transition between small black holes and the thermal AdS space similar to Hawking-Page phase transition. In order to demonstrate the two broad categories, we have focused on $N =1, \frac{2}{3}$ and $N = \frac{6}{7}$ black holes in detail. We computed the first law and the Smarr relations for the black hole and introduced two new thermodynamical parameters in order to satisfy the first law. We computed specific heat capacities, internal energy and free energy for black holes and studied local and global stability of the black hole. We have also studied the Joule-Thomson expansion for the black hole. It is also noted that unlike the charged BTZ black hole, the charged dilaton black hole does not violate the Reverse Isoperimetric Inequality for certain values of parameters of the theory. |
2405.16673 | Nikodem Poplawski | Nikodem Pop{\l}awski | Black holes in the expanding Universe | 6 pages, 1 figure | null | null | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | If the Universe is closed, there must exist a constant and positive energy
density of vacuum (cosmological constant). By analyzing the McVittie metric, we
show that in the expanding Universe: the Hubble parameters at the event
horizons of all centrally symmetric black holes are equal and related to the
cosmological constant, black holes do not grow with the expansion of the
Universe, and different regions of the Universe expand at different rates
(Hubble tension).
| [
{
"created": "Sun, 26 May 2024 19:32:24 GMT",
"version": "v1"
}
] | 2024-06-04 | [
[
"Popławski",
"Nikodem",
""
]
] | If the Universe is closed, there must exist a constant and positive energy density of vacuum (cosmological constant). By analyzing the McVittie metric, we show that in the expanding Universe: the Hubble parameters at the event horizons of all centrally symmetric black holes are equal and related to the cosmological constant, black holes do not grow with the expansion of the Universe, and different regions of the Universe expand at different rates (Hubble tension). |
2105.11817 | Demetrios Kotopoloulis | Demetrios Kotopoulis and Charis Anastopoulos | Thermodynamics and phase transitions of black holes in contact with a
gravitating heat bath | 31 pages, 12 figures | null | 10.1088/1361-6382/ac2137 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We study the thermodynamics of a shell of self-gravitating radiation, bounded
by two spherical surfaces. This system provides a consistent model for a
gravitating thermal reservoir for different solutions to vacuum Einstein
equations in the shell's interior. The latter include black holes and flat
space, hence, this model allows for the study of black hole phase transitions.
Following the analysis of arXiv:1103.3898 , we show that the inclusion of
appropriate entropy terms to the spacetime boundaries (including the
Bekenstein-Hawking entropy for black hole horizons) leads to a consistent
thermodynamic description. The system is characterized by four phases, two
black hole phases distinguished by the size of the horizon, a flat space phase
and one phase that describes naked singularities. We undertake a detailed
analysis of black-hole phase transitions, the non-concave entropy function, the
properties of temperature at infinity, and system's heat capacity.
| [
{
"created": "Tue, 25 May 2021 10:36:08 GMT",
"version": "v1"
}
] | 2021-09-22 | [
[
"Kotopoulis",
"Demetrios",
""
],
[
"Anastopoulos",
"Charis",
""
]
] | We study the thermodynamics of a shell of self-gravitating radiation, bounded by two spherical surfaces. This system provides a consistent model for a gravitating thermal reservoir for different solutions to vacuum Einstein equations in the shell's interior. The latter include black holes and flat space, hence, this model allows for the study of black hole phase transitions. Following the analysis of arXiv:1103.3898 , we show that the inclusion of appropriate entropy terms to the spacetime boundaries (including the Bekenstein-Hawking entropy for black hole horizons) leads to a consistent thermodynamic description. The system is characterized by four phases, two black hole phases distinguished by the size of the horizon, a flat space phase and one phase that describes naked singularities. We undertake a detailed analysis of black-hole phase transitions, the non-concave entropy function, the properties of temperature at infinity, and system's heat capacity. |
gr-qc/9507054 | Carsten Gundlach | Carsten Gundlach | The Choptuik spacetime as an eigenvalue problem | Review section rewritten; sign error in equation (4), error
concerning non-minimally coupled scalar field, one typo in table corrected,
references added. To be published in Phys. Rev. Lett | Phys.Rev.Lett. 75 (1995) 3214-3217 | 10.1103/PhysRevLett.75.3214 | LAEFF-95/09 | gr-qc | null | By fine-tuning generic Cauchy data, critical phenomena have recently been
discovered in the black hole/no black hole "phase transition" of various
gravitating systems. For the spherisymmetric real scalar field system, we find
the "critical" spacetime separating the two phases by demanding discrete
scale-invariance, analyticity, and an additional reflection-type symmetry. The
resulting nonlinear hyperbolic boundary value problem, with the rescaling
factor Delta as the eigenvalue, is solved numerically by relaxation. We find
Delta = 3.4439 +/- 0.0004.
| [
{
"created": "Thu, 27 Jul 1995 14:50:33 GMT",
"version": "v1"
},
{
"created": "Wed, 13 Sep 1995 10:19:46 GMT",
"version": "v2"
}
] | 2009-10-28 | [
[
"Gundlach",
"Carsten",
""
]
] | By fine-tuning generic Cauchy data, critical phenomena have recently been discovered in the black hole/no black hole "phase transition" of various gravitating systems. For the spherisymmetric real scalar field system, we find the "critical" spacetime separating the two phases by demanding discrete scale-invariance, analyticity, and an additional reflection-type symmetry. The resulting nonlinear hyperbolic boundary value problem, with the rescaling factor Delta as the eigenvalue, is solved numerically by relaxation. We find Delta = 3.4439 +/- 0.0004. |
1405.6121 | Vladimir Dzhunushaliev | Vladimir Dzhunushaliev and Vladimir Folomeev | Propagation of gravitational waves in the nonperturbative spinor vacuum | some changes | null | 10.1140/epjc/s10052-014-3057-2 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The propagation of gravitational waves on the background of a nonperturbative
vacuum of a spinor field is considered. It is shown that there are several
distinctive features in comparison with the propagation of plane gravitational
waves through empty space: there exists the fixed phase difference between the
$h_{yy,zz}$ and $h_{yz}$ components of the wave; the phase and group velocities
of gravitational waves are not equal to the velocity of light; the group
velocity is always less than the velocity of light; under some conditions the
gravitational waves are either damped or absent; for given frequency, there
exist two waves with different wave vectors. We also discuss the possibility of
experimental verification of the obtained effects as a tool to investigate
nonperurbative quantum field theories.
| [
{
"created": "Fri, 23 May 2014 16:53:08 GMT",
"version": "v1"
},
{
"created": "Thu, 24 Jul 2014 08:19:18 GMT",
"version": "v2"
},
{
"created": "Tue, 2 Sep 2014 02:39:16 GMT",
"version": "v3"
}
] | 2015-06-19 | [
[
"Dzhunushaliev",
"Vladimir",
""
],
[
"Folomeev",
"Vladimir",
""
]
] | The propagation of gravitational waves on the background of a nonperturbative vacuum of a spinor field is considered. It is shown that there are several distinctive features in comparison with the propagation of plane gravitational waves through empty space: there exists the fixed phase difference between the $h_{yy,zz}$ and $h_{yz}$ components of the wave; the phase and group velocities of gravitational waves are not equal to the velocity of light; the group velocity is always less than the velocity of light; under some conditions the gravitational waves are either damped or absent; for given frequency, there exist two waves with different wave vectors. We also discuss the possibility of experimental verification of the obtained effects as a tool to investigate nonperurbative quantum field theories. |
1909.02143 | Nicholas Loutrel | Nicholas Loutrel | Analytic Waveforms for Eccentric Gravitational Wave Bursts | 22 pages, 9 figures, updating to reflect the published version | Classical & Quantum Gravity 37 (2020), no. 7, 075008 | 10.1088/1361-6382/ab745f | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We here present the first analytic effective fly-by (EFB) waveforms designed
to accurately capture the burst of gravitational radiation from the closest
approach of highly eccentric compact binaries. The waveforms are constructed by
performing a re-summation procedure on the well-known Fourier series
representation of the two-body problem at leading post-Newtonian order. This
procedure results in two models: one in the time-domain, and one in the Fourier
domain, which makes use of the stationary phase approximation. We discuss the
computational efficiency of these models, and find that the time-domain model
is roughly twice as fast as a numerical quadrupole waveform. We compare the
time-domain model to both numerical, leading post-Newtonian order, quadrupole
waveforms and numerical relativity fly-by waveforms using the match statistic.
While the match is typically $>0.97$ when compared to the quadrupole waveforms,
it is much lower when comparing to the numerical relativity fly-by waveforms,
due to neglecting relativistic effects within the model. We further show how to
use these individual waveforms to detect a repeated burst source.
| [
{
"created": "Wed, 4 Sep 2019 22:37:15 GMT",
"version": "v1"
},
{
"created": "Mon, 30 Mar 2020 18:02:59 GMT",
"version": "v2"
}
] | 2020-04-01 | [
[
"Loutrel",
"Nicholas",
""
]
] | We here present the first analytic effective fly-by (EFB) waveforms designed to accurately capture the burst of gravitational radiation from the closest approach of highly eccentric compact binaries. The waveforms are constructed by performing a re-summation procedure on the well-known Fourier series representation of the two-body problem at leading post-Newtonian order. This procedure results in two models: one in the time-domain, and one in the Fourier domain, which makes use of the stationary phase approximation. We discuss the computational efficiency of these models, and find that the time-domain model is roughly twice as fast as a numerical quadrupole waveform. We compare the time-domain model to both numerical, leading post-Newtonian order, quadrupole waveforms and numerical relativity fly-by waveforms using the match statistic. While the match is typically $>0.97$ when compared to the quadrupole waveforms, it is much lower when comparing to the numerical relativity fly-by waveforms, due to neglecting relativistic effects within the model. We further show how to use these individual waveforms to detect a repeated burst source. |
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