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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
gr-qc/9901072
|
Kostas Kokkotas
|
K. D. Kokkotas, T. A. Apostolatos and N. Andersson
|
The inverse problem for pulsating neutron stars: A ``fingerprint
analysis'' for the supranuclear equation of state
|
9 pages, 3 figures
|
Mon.Not.Roy.Astron.Soc. 320 (2001) 307-315
|
10.1046/j.1365-8711.2001.03945.x
| null |
gr-qc astro-ph
| null |
We study the problem of detecting, and infering astrophysical information
from, gravitational waves from a pulsating neutron star. We show that the fluid
f and p-modes, as well as the gravitational-wave w-modes may be detectable from
sources in our own galaxy, and investigate how accurately the frequencies and
damping rates of these modes can be infered from a noisy gravitational-wave
data stream. Based on the conclusions of this discussion we propose a strategy
for revealing the supranuclear equation of state using the neutron star
fingerprints: the observed frequencies of an f and a p-mode. We also discuss
how well the source can be located in the sky using observations with several
detectors.
|
[
{
"created": "Mon, 25 Jan 1999 19:41:46 GMT",
"version": "v1"
}
] |
2009-10-31
|
[
[
"Kokkotas",
"K. D.",
""
],
[
"Apostolatos",
"T. A.",
""
],
[
"Andersson",
"N.",
""
]
] |
We study the problem of detecting, and infering astrophysical information from, gravitational waves from a pulsating neutron star. We show that the fluid f and p-modes, as well as the gravitational-wave w-modes may be detectable from sources in our own galaxy, and investigate how accurately the frequencies and damping rates of these modes can be infered from a noisy gravitational-wave data stream. Based on the conclusions of this discussion we propose a strategy for revealing the supranuclear equation of state using the neutron star fingerprints: the observed frequencies of an f and a p-mode. We also discuss how well the source can be located in the sky using observations with several detectors.
|
0912.2384
|
Christian Schubert
|
Jose Manuel Davila and Christian Schubert
|
Effective action for Einstein-Maxwell theory at order RF**4
|
13 pages, no figures
|
Class.Quant.Grav.27:075007,2010
|
10.1088/0264-9381/27/7/075007
|
Preprint AEI-2009-081
|
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We use a recently derived integral representation of the one-loop effective
action in Einstein-Maxwell theory for an explicit calculation of the part of
the effective action containing the information on the low energy limit of the
five-point amplitudes involving one graviton, four photons and either a scalar
or spinor loop. All available identities are used to get the result into a
relatively compact form.
|
[
{
"created": "Sat, 12 Dec 2009 00:57:43 GMT",
"version": "v1"
}
] |
2010-04-21
|
[
[
"Davila",
"Jose Manuel",
""
],
[
"Schubert",
"Christian",
""
]
] |
We use a recently derived integral representation of the one-loop effective action in Einstein-Maxwell theory for an explicit calculation of the part of the effective action containing the information on the low energy limit of the five-point amplitudes involving one graviton, four photons and either a scalar or spinor loop. All available identities are used to get the result into a relatively compact form.
|
1109.6848
|
Alexandre Le Tiec
|
Alexandre Le Tiec
|
Perturbative, Post-Newtonian, and General Relativistic Dynamics of Black
Hole Binaries
|
4 pages, 2 figures; to appear in the Proceedings of the "46th
Rencontres de Moriond & GPhyS Colloquium on Gravitational Waves and
Experimental Gravity", La Thuile (Italy), March 2011
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The orbital motion of inspiralling and coalescing black hole binaries can be
investigated using a variety of approximation schemes and numerical methods
within general relativity: post-Newtonian expansions, black hole perturbation
theory, numerical relativity, and the effective-one-body formalism. We review
two recent comparisons of the predictions from these various techniques. Both
comparisons rely on the calculation of a coordinate invariant relation, in the
case of non-spinning binary black holes on quasi-circular orbits. All methods
are shown to agree very well in their common domain of validity.
|
[
{
"created": "Fri, 30 Sep 2011 15:13:47 GMT",
"version": "v1"
}
] |
2011-10-03
|
[
[
"Tiec",
"Alexandre Le",
""
]
] |
The orbital motion of inspiralling and coalescing black hole binaries can be investigated using a variety of approximation schemes and numerical methods within general relativity: post-Newtonian expansions, black hole perturbation theory, numerical relativity, and the effective-one-body formalism. We review two recent comparisons of the predictions from these various techniques. Both comparisons rely on the calculation of a coordinate invariant relation, in the case of non-spinning binary black holes on quasi-circular orbits. All methods are shown to agree very well in their common domain of validity.
|
2404.02019
|
Abra\~ao Mendes
|
Gregory J. Galloway and Abra\~ao Mendes
|
Aspects of the geometry and topology of expanding horizons
|
10 pages, 1 figure. Comments welcome
| null | null | null |
gr-qc math.DG
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The aim of this paper is to extend some basic results about marginally outer
trapped surfaces to the context of surfaces having general null expansion.
Motivated in part by recent work of Chai-Wan, we introduce the notion of
$\mathfrak{g}$-stability for a general closed hypersurface $\Sigma$ in an
ambient initial data set and prove that, under natural energy conditions,
$\Sigma$ has positive Yamabe type, that is, $\Sigma$ admits a metric of
positive scalar curvature, provided $\Sigma$ is $\mathfrak{g}$-stable. Similar
results are obtained when $\Sigma$ is embedded in a spacelike, or null,
hypersurface of a spacetime satisfying the dominant energy condition.
Conditions implying $\mathfrak{g}$-stability are also discussed. Finally, we
obtain a spacetime positive mass theorem for initial data sets with compact
boundary $\Sigma$ of positive null expansion, assuming that the dominant energy
condition is sufficiently strict near $\Sigma$. This extends recent results of
Galloway-Lee and Lee-Lesourd-Unger.
|
[
{
"created": "Tue, 2 Apr 2024 15:09:22 GMT",
"version": "v1"
}
] |
2024-04-03
|
[
[
"Galloway",
"Gregory J.",
""
],
[
"Mendes",
"Abraão",
""
]
] |
The aim of this paper is to extend some basic results about marginally outer trapped surfaces to the context of surfaces having general null expansion. Motivated in part by recent work of Chai-Wan, we introduce the notion of $\mathfrak{g}$-stability for a general closed hypersurface $\Sigma$ in an ambient initial data set and prove that, under natural energy conditions, $\Sigma$ has positive Yamabe type, that is, $\Sigma$ admits a metric of positive scalar curvature, provided $\Sigma$ is $\mathfrak{g}$-stable. Similar results are obtained when $\Sigma$ is embedded in a spacelike, or null, hypersurface of a spacetime satisfying the dominant energy condition. Conditions implying $\mathfrak{g}$-stability are also discussed. Finally, we obtain a spacetime positive mass theorem for initial data sets with compact boundary $\Sigma$ of positive null expansion, assuming that the dominant energy condition is sufficiently strict near $\Sigma$. This extends recent results of Galloway-Lee and Lee-Lesourd-Unger.
|
1606.03952
|
Alessandro Nagar
|
Walter Del Pozzo and Alessandro Nagar
|
An analytic family of post-merger template waveforms
|
14 pages, 7 figures, submitted to Phys. Rev. D. Revised and more
detailed version. Results unchanged
|
Phys. Rev. D 95, 124034 (2017)
|
10.1103/PhysRevD.95.124034
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Building on the analytical description of the post-merger (ringdown) waveform
of coalescing, non-precessing, spinning, (BBHs) introduced in Phys. Rev. D 90,
024054 (2014), we propose an analytic, closed form, time-domain, representation
of the $\ell=m=2$ gravitational radiation mode emitted after merger. This
expression is given as a function of the component masses and dimensionless
spins $(m_{1,2},\chi_{1,2})$ of the two inspiralling objects, as well as of the
mass $M_{\rm BH}$ and (complex) frequency $\sigma_{1}$ of the fundamental
quasi-normal mode of the remnant black hole. Our proposed template is obtained
by fitting the post-merger waveform part of several publicly available
numerical relativity simulations from the Simulating eXtreme Spacetimes (SXS)
catalog and then suitably interpolating over (symmetric) mass ratio and spins.
We show that this analytic expression accurately reproduces ($\sim$~0.01 rad)
the phasing of the post-merger data of other datasets not used in its
construction. This is notably the case of the spin-aligned run SXS:BBH:0305,
whose intrinsic parameters are consistent with the 90\% credible intervals
reported by the parameter-estimation followup of GW150914 in Phys. Rev. Lett.
116 (2016) no.24, 241102. Using SXS waveforms as "experimental" data, we
further show that our template could be used on the actual GW150914 data to
perform a new measure the complex frequency of the fundamental quasi-normal
mode so to exploit the complete (high signal-to-noise-ratio) post-merger
waveform.
|
[
{
"created": "Mon, 13 Jun 2016 13:58:06 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Nov 2016 10:05:23 GMT",
"version": "v2"
},
{
"created": "Wed, 11 Jan 2017 12:07:52 GMT",
"version": "v3"
},
{
"created": "Thu, 12 Jan 2017 13:44:59 GMT",
"version": "v4"
}
] |
2017-06-28
|
[
[
"Del Pozzo",
"Walter",
""
],
[
"Nagar",
"Alessandro",
""
]
] |
Building on the analytical description of the post-merger (ringdown) waveform of coalescing, non-precessing, spinning, (BBHs) introduced in Phys. Rev. D 90, 024054 (2014), we propose an analytic, closed form, time-domain, representation of the $\ell=m=2$ gravitational radiation mode emitted after merger. This expression is given as a function of the component masses and dimensionless spins $(m_{1,2},\chi_{1,2})$ of the two inspiralling objects, as well as of the mass $M_{\rm BH}$ and (complex) frequency $\sigma_{1}$ of the fundamental quasi-normal mode of the remnant black hole. Our proposed template is obtained by fitting the post-merger waveform part of several publicly available numerical relativity simulations from the Simulating eXtreme Spacetimes (SXS) catalog and then suitably interpolating over (symmetric) mass ratio and spins. We show that this analytic expression accurately reproduces ($\sim$~0.01 rad) the phasing of the post-merger data of other datasets not used in its construction. This is notably the case of the spin-aligned run SXS:BBH:0305, whose intrinsic parameters are consistent with the 90\% credible intervals reported by the parameter-estimation followup of GW150914 in Phys. Rev. Lett. 116 (2016) no.24, 241102. Using SXS waveforms as "experimental" data, we further show that our template could be used on the actual GW150914 data to perform a new measure the complex frequency of the fundamental quasi-normal mode so to exploit the complete (high signal-to-noise-ratio) post-merger waveform.
|
1111.6342
|
Changjun Gao
|
Changjun Gao
|
Introduction of the generalized Lorenz gauge condition into the
vector-tensor theory
|
7 pages, 1 figure
|
Phys. Rev. D 85, 023533(2012)
|
10.1103/PhysRevD.85.023533
| null |
gr-qc astro-ph.CO hep-ph hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We introduce the generalized Lorentz gauge condition in the theory of quantum
electrodynamics into the general vector-tensor theories of gravity. Then we
explore the cosmic evolution and the static, spherically symmetric solution of
the four dimensional vector field with the generalized Lorenz gauge. We find
that, if the vector field is minimally coupled to the gravitation, it behaves
as the cosmological constant. On the other hand, if it is nonminimally coupled
to the gravitation, the vector field could behave as vast matters in the
background of spatially flat Friedmann-Robertson-Walker Universe. But it may be
not the case. The weak, strong and dominant energy conditions, the stability
analysis of classical and quantum aspects would put constraints on the
parameters and so the equation of state of matters would be greatly
constrained.
|
[
{
"created": "Mon, 28 Nov 2011 04:34:59 GMT",
"version": "v1"
},
{
"created": "Sat, 14 Jan 2012 06:21:38 GMT",
"version": "v2"
},
{
"created": "Mon, 30 Jan 2012 07:03:11 GMT",
"version": "v3"
}
] |
2013-05-30
|
[
[
"Gao",
"Changjun",
""
]
] |
We introduce the generalized Lorentz gauge condition in the theory of quantum electrodynamics into the general vector-tensor theories of gravity. Then we explore the cosmic evolution and the static, spherically symmetric solution of the four dimensional vector field with the generalized Lorenz gauge. We find that, if the vector field is minimally coupled to the gravitation, it behaves as the cosmological constant. On the other hand, if it is nonminimally coupled to the gravitation, the vector field could behave as vast matters in the background of spatially flat Friedmann-Robertson-Walker Universe. But it may be not the case. The weak, strong and dominant energy conditions, the stability analysis of classical and quantum aspects would put constraints on the parameters and so the equation of state of matters would be greatly constrained.
|
2304.13137
|
Himanshu Chaudhary
|
Amine Bouali, Himanshu Chaudhary, Ujjal Debnath, Alok Sardar,
G.Mustafa
|
Data Analysis of three parameter models of deceleration parameter in FRW
Universe
| null | null |
10.1140/epjp/s13360-023-04442-y
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Constraining the dark energy deceleration parameter is one of the fascinating
topics in the recent cosmological paradigm. This work aims to reconstruct the
dark energy using parametrization of the deceleration parameter in a flat FRW
universe filled with radiation, dark energy, and pressure-less dark matter.
Thus, we have considered four well-motivated parameterizations of q(z), which
can provide the evolution scenario from the deceleration to acceleration phase
of the Universe. We have evaluated the expression of the corresponding Hubble
parameter of each parametrization by imposing it into the Friedmann equation.
We have constrained the model parameter through H(z), Pantheon, and baryons
acoustic oscillation (BOA) data. Next, we have estimated the best-fit values of
the model parameters by using Monte Carlo Markov Chain (MCMC) technique and
implementing H(z)+ BAO+SNe-Ia dataset. Then we analyzed the cosmographic
parameter, such as deceleration, jerk, and snap parameters, graphically by
employing the best-fit values of the model parameter. Moreover, we have
analyzed statefinder and Om diagnostics parameters for each scenario to
discriminate various dark energy models. Using the information criteria, the
viability of the models have examined. In the end, we have analogized our
outcomes with the standard {\Lambda}CDM model to examine the viability of our
models
|
[
{
"created": "Tue, 25 Apr 2023 20:27:06 GMT",
"version": "v1"
},
{
"created": "Fri, 22 Sep 2023 22:13:52 GMT",
"version": "v2"
}
] |
2023-09-26
|
[
[
"Bouali",
"Amine",
""
],
[
"Chaudhary",
"Himanshu",
""
],
[
"Debnath",
"Ujjal",
""
],
[
"Sardar",
"Alok",
""
],
[
"Mustafa",
"G.",
""
]
] |
Constraining the dark energy deceleration parameter is one of the fascinating topics in the recent cosmological paradigm. This work aims to reconstruct the dark energy using parametrization of the deceleration parameter in a flat FRW universe filled with radiation, dark energy, and pressure-less dark matter. Thus, we have considered four well-motivated parameterizations of q(z), which can provide the evolution scenario from the deceleration to acceleration phase of the Universe. We have evaluated the expression of the corresponding Hubble parameter of each parametrization by imposing it into the Friedmann equation. We have constrained the model parameter through H(z), Pantheon, and baryons acoustic oscillation (BOA) data. Next, we have estimated the best-fit values of the model parameters by using Monte Carlo Markov Chain (MCMC) technique and implementing H(z)+ BAO+SNe-Ia dataset. Then we analyzed the cosmographic parameter, such as deceleration, jerk, and snap parameters, graphically by employing the best-fit values of the model parameter. Moreover, we have analyzed statefinder and Om diagnostics parameters for each scenario to discriminate various dark energy models. Using the information criteria, the viability of the models have examined. In the end, we have analogized our outcomes with the standard {\Lambda}CDM model to examine the viability of our models
|
1210.2299
|
Carlos Palenzuela
|
Susana Valdez-Alvarado, Carlos Palenzuela, Daniela Alic, L. Arturo
Ure\~na-L\'opez
|
Dynamical evolution of fermion-boson stars
|
13 pages, 9 figures. Replaced with the journal final version
|
Phys. Rev. D 87, 084040 (2013)
|
10.1103/PhysRevD.87.084040
| null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Compact objects, like neutron stars and white dwarfs, may accrete dark
matter, and then be sensitive probes of its presence. These compact stars with
a dark matter component can be modeled by a perfect fluid minimally coupled to
a complex scalar field (representing a bosonic dark matter component),
resulting in objects known as fermion-boson stars. We have performed the
dynamical evolution of these stars in order to analyze their stability, and to
study their spectrum of normal modes, which may reveal the amount of dark
matter in the system. Their stability analysis shows a structure similar to
that of an isolated (fermion or boson) star, with equilibrium configurations
either laying on the stable or on the unstable branch. The analysis of the
spectrum of normal modes indicates the presence of new oscillation modes in the
fermionic part of the star, which result from the coupling to the bosonic
component through the gravity.
|
[
{
"created": "Mon, 8 Oct 2012 14:52:40 GMT",
"version": "v1"
},
{
"created": "Sun, 1 Nov 2015 11:15:52 GMT",
"version": "v2"
}
] |
2015-11-03
|
[
[
"Valdez-Alvarado",
"Susana",
""
],
[
"Palenzuela",
"Carlos",
""
],
[
"Alic",
"Daniela",
""
],
[
"Ureña-López",
"L. Arturo",
""
]
] |
Compact objects, like neutron stars and white dwarfs, may accrete dark matter, and then be sensitive probes of its presence. These compact stars with a dark matter component can be modeled by a perfect fluid minimally coupled to a complex scalar field (representing a bosonic dark matter component), resulting in objects known as fermion-boson stars. We have performed the dynamical evolution of these stars in order to analyze their stability, and to study their spectrum of normal modes, which may reveal the amount of dark matter in the system. Their stability analysis shows a structure similar to that of an isolated (fermion or boson) star, with equilibrium configurations either laying on the stable or on the unstable branch. The analysis of the spectrum of normal modes indicates the presence of new oscillation modes in the fermionic part of the star, which result from the coupling to the bosonic component through the gravity.
|
0706.3018
|
Salvatore Capozziello
|
S. Capozziello, V.I. Man'ko, G. Marmo, C. Stornaiolo
|
Tomographic Representation of Minisuperspace Quantum Cosmology and
Noether Symmetries
|
15 pages
|
Gen.Rel.Grav.40:2627-2647,2008
|
10.1007/s10714-008-0643-3
| null |
gr-qc hep-th
| null |
The probability representation, in which cosmological quantum states are
described by a standard positive probability distribution, is constructed for
minisuperspace models selected by Noether symmetries. In such a case, the
tomographic probability distribution provides the classical evolution for the
models and can be considered an approach to select "observable" universes. Some
specific examples, derived from Extended Theories of Gravity, are worked out.
We discuss also how to connect tomograms, symmetries and cosmological
parameters.
|
[
{
"created": "Wed, 20 Jun 2007 16:08:21 GMT",
"version": "v1"
},
{
"created": "Wed, 22 Aug 2007 14:10:58 GMT",
"version": "v2"
},
{
"created": "Wed, 2 Apr 2008 12:22:57 GMT",
"version": "v3"
}
] |
2008-12-18
|
[
[
"Capozziello",
"S.",
""
],
[
"Man'ko",
"V. I.",
""
],
[
"Marmo",
"G.",
""
],
[
"Stornaiolo",
"C.",
""
]
] |
The probability representation, in which cosmological quantum states are described by a standard positive probability distribution, is constructed for minisuperspace models selected by Noether symmetries. In such a case, the tomographic probability distribution provides the classical evolution for the models and can be considered an approach to select "observable" universes. Some specific examples, derived from Extended Theories of Gravity, are worked out. We discuss also how to connect tomograms, symmetries and cosmological parameters.
|
gr-qc/9507039
|
Arlen Anderson
|
Arlen Anderson
|
Clocks and Time
|
LaTeX, 19 pp
| null | null |
IFP-UNC-95-512
|
gr-qc
| null |
A general definition of a clock is proposed, and the role of clocks in
establishing temporal pre-conditions in quantum mechanical questions is
critically discussed. The different status of clocks as used by theorists
external to a system and as used by participant-observers within a system is
emphasized. It is shown that the foliation of spacetime into instants of time
is necessary to correctly interpret the readings of clocks and that clocks are
thus insufficient to reconstruct time in the absence of such a foliation.
|
[
{
"created": "Tue, 18 Jul 1995 03:25:53 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Anderson",
"Arlen",
""
]
] |
A general definition of a clock is proposed, and the role of clocks in establishing temporal pre-conditions in quantum mechanical questions is critically discussed. The different status of clocks as used by theorists external to a system and as used by participant-observers within a system is emphasized. It is shown that the foliation of spacetime into instants of time is necessary to correctly interpret the readings of clocks and that clocks are thus insufficient to reconstruct time in the absence of such a foliation.
|
2006.09910
|
Cyril Renevey
|
Cyril Renevey, Joe Kennedy, Lucas Lombriser
|
Parameterised post-Newtonian formalism for the effective field theory of
dark energy via screened reconstructed Horndeski theories
|
40 pages, 1 figure, 2 tables
|
JCAP12(2020)032
|
10.1088/1475-7516/2020/12/032
| null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We bring together two popular formalisms which generically parameterise
deviations from General Relativity on astrophysical and cosmological scales,
namely the parameterised post-Newtonian (PPN) formalism and the effective field
theory (EFT) of dark energy and modified gravity. These separate formalisms are
successfully applied to independently perform tests of gravity in their
respective regimes of applicability on vastly different length scales.
Nonlinear screening mechanisms indeed make it imperative to probe General
Relativity across a wide range of scales. For a comprehensive interpretation of
the complementary measurements it is important to connect them to effectively
constrain the vast gravitational model space. We establish such a connection
within the framework of Horndeski scalar-tensor theories restricted to a
luminal propagation speed of gravitational waves. This is possible via the
reconstruction of the family of linearly degenerate covariant Horndeski actions
from the set of EFT functions and the subsequent derivation of the PPN
parameters from the reconstructed theory. We outline the required conditions
which ensure a reconstructed Horndeski model possesses a screening mechanism
that enables significant modifications on cosmological scales while respecting
stringent astrophysical bounds. Employing a scaling method, we then perform the
general post-Newtonian expansion of the reconstructed models to derive their
PPN parameters $\gamma$ and $\beta$ in their screened regimes.
|
[
{
"created": "Wed, 17 Jun 2020 14:43:57 GMT",
"version": "v1"
},
{
"created": "Thu, 28 Jan 2021 11:10:43 GMT",
"version": "v2"
}
] |
2021-01-29
|
[
[
"Renevey",
"Cyril",
""
],
[
"Kennedy",
"Joe",
""
],
[
"Lombriser",
"Lucas",
""
]
] |
We bring together two popular formalisms which generically parameterise deviations from General Relativity on astrophysical and cosmological scales, namely the parameterised post-Newtonian (PPN) formalism and the effective field theory (EFT) of dark energy and modified gravity. These separate formalisms are successfully applied to independently perform tests of gravity in their respective regimes of applicability on vastly different length scales. Nonlinear screening mechanisms indeed make it imperative to probe General Relativity across a wide range of scales. For a comprehensive interpretation of the complementary measurements it is important to connect them to effectively constrain the vast gravitational model space. We establish such a connection within the framework of Horndeski scalar-tensor theories restricted to a luminal propagation speed of gravitational waves. This is possible via the reconstruction of the family of linearly degenerate covariant Horndeski actions from the set of EFT functions and the subsequent derivation of the PPN parameters from the reconstructed theory. We outline the required conditions which ensure a reconstructed Horndeski model possesses a screening mechanism that enables significant modifications on cosmological scales while respecting stringent astrophysical bounds. Employing a scaling method, we then perform the general post-Newtonian expansion of the reconstructed models to derive their PPN parameters $\gamma$ and $\beta$ in their screened regimes.
|
2307.01598
|
Kenneth Chen
|
Kenneth Chen and Lap-Ming Lin
|
Fully general relativistic simulations of rapidly rotating quark stars:
Oscillation modes and universal relations
|
22 pages, 20 figures
|
Phys. Rev. D 108, 064007 (2023)
|
10.1103/PhysRevD.108.064007
| null |
gr-qc astro-ph.HE physics.comp-ph
|
http://creativecommons.org/licenses/by/4.0/
|
(Abridged) Numerical simulation of strange quark stars (QSs) is challenging
due to the strong density discontinuity at the stellar surface. In this paper,
we report successful simulations of rapidly rotating QSs and study their
oscillation modes in full general relativity. Building on top of the numerical
relativity code \texttt{Einstein Toolkit}, we implement a positivity-preserving
Riemann solver and a dust-like atmosphere to handle the density discontinuity
at the surface. We demonstrate the robustness of our numerical method by
performing stable evolutions of rotating QSs close to the Keplerian limit and
extracting their oscillation modes. We focus on the quadrupolar $l=|m|=2$
$f$-mode and study whether they can still satisfy the universal relations
recently proposed for rotating neutron stars (NSs). We find that two of the
three proposed relations can still be satisfied by rotating QSs. For the
remaining broken relation, we propose a new relation to unify the NS and QS
data by invoking the dimensionless spin parameter $j$. The onsets of secular
instabilities for rotating QSs are also studied by analyzing the $f$-mode
frequencies. Same as the result found previously for NSs, we find that QSs
become unstable to the Chandrasekhar-Friedman-Schutz instability when the
angular velocity of the star $\Omega \approx 3.4 \sigma_0$ for sequences of
constant central energy density, where $\sigma_0$ is the mode frequency of the
corresponding nonrotating configurations. For the viscosity-driven instability,
we find that QSs become unstable when $j\approx 0.881$ for both sequences of
constant central energy density and constant baryon mass. Such a high value of
$j$ cannot be achieved by realistic rotating NSs before reaching the Keplerian
limit.
|
[
{
"created": "Tue, 4 Jul 2023 09:38:49 GMT",
"version": "v1"
},
{
"created": "Fri, 1 Sep 2023 16:57:34 GMT",
"version": "v2"
}
] |
2023-09-08
|
[
[
"Chen",
"Kenneth",
""
],
[
"Lin",
"Lap-Ming",
""
]
] |
(Abridged) Numerical simulation of strange quark stars (QSs) is challenging due to the strong density discontinuity at the stellar surface. In this paper, we report successful simulations of rapidly rotating QSs and study their oscillation modes in full general relativity. Building on top of the numerical relativity code \texttt{Einstein Toolkit}, we implement a positivity-preserving Riemann solver and a dust-like atmosphere to handle the density discontinuity at the surface. We demonstrate the robustness of our numerical method by performing stable evolutions of rotating QSs close to the Keplerian limit and extracting their oscillation modes. We focus on the quadrupolar $l=|m|=2$ $f$-mode and study whether they can still satisfy the universal relations recently proposed for rotating neutron stars (NSs). We find that two of the three proposed relations can still be satisfied by rotating QSs. For the remaining broken relation, we propose a new relation to unify the NS and QS data by invoking the dimensionless spin parameter $j$. The onsets of secular instabilities for rotating QSs are also studied by analyzing the $f$-mode frequencies. Same as the result found previously for NSs, we find that QSs become unstable to the Chandrasekhar-Friedman-Schutz instability when the angular velocity of the star $\Omega \approx 3.4 \sigma_0$ for sequences of constant central energy density, where $\sigma_0$ is the mode frequency of the corresponding nonrotating configurations. For the viscosity-driven instability, we find that QSs become unstable when $j\approx 0.881$ for both sequences of constant central energy density and constant baryon mass. Such a high value of $j$ cannot be achieved by realistic rotating NSs before reaching the Keplerian limit.
|
1309.0915
|
Hwa-Tung Nieh
|
H.T Nieh
|
A Torsional Topological Invariant
|
10 pages
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Curvature and torsion are the two tensors characterizing a general Riemannian
spacetime. In Einstein's general theory of gravitation, with torsion postulated
to vanish and the affine connection identified to the Christoffel symbol, only
the curvature tensor plays the central role. For such a purely metric geometry,
two well-known topological invariants, namely the Euler class and the
Pontryagin class, are useful in characterizing the topological properties of
the spacetime. From a gauge theory point of view, and especially in the
presence of spin, torsion naturally comes into play, and the underlying
spacetime is no longer purely metric. We describe a torsional topological
invariant, discovered in 1982, that has now found increasing usefulness in
recent developments.
|
[
{
"created": "Wed, 4 Sep 2013 05:18:23 GMT",
"version": "v1"
}
] |
2013-09-05
|
[
[
"Nieh",
"H. T",
""
]
] |
Curvature and torsion are the two tensors characterizing a general Riemannian spacetime. In Einstein's general theory of gravitation, with torsion postulated to vanish and the affine connection identified to the Christoffel symbol, only the curvature tensor plays the central role. For such a purely metric geometry, two well-known topological invariants, namely the Euler class and the Pontryagin class, are useful in characterizing the topological properties of the spacetime. From a gauge theory point of view, and especially in the presence of spin, torsion naturally comes into play, and the underlying spacetime is no longer purely metric. We describe a torsional topological invariant, discovered in 1982, that has now found increasing usefulness in recent developments.
|
gr-qc/9303015
|
B. Bruegmann
|
Bernd Bruegmann
|
Bibliography of Publications related to Classical and Quantum Gravity in
terms of the Ashtekar Variables
|
15 pages (LaTeX), MPI-Ph/93-68 (Sept. 93)
| null | null | null |
gr-qc hep-th
| null |
This bibliography attempts to give a comprehensive overview of all the
literature related to the Ashtekar variables. The original version was compiled
by Peter Huebner in 1989, and it has been subsequently updated by Gabriela
Gonzalez and Bernd Bruegmann. Information about additional literature, new
preprints, and especially corrections are always welcome.
|
[
{
"created": "Wed, 10 Mar 1993 19:52:13 GMT",
"version": "v1"
},
{
"created": "Sat, 11 Sep 1993 20:57:47 GMT",
"version": "v2"
},
{
"created": "Fri, 24 Sep 1993 15:24:03 GMT",
"version": "v3"
}
] |
2008-02-03
|
[
[
"Bruegmann",
"Bernd",
""
]
] |
This bibliography attempts to give a comprehensive overview of all the literature related to the Ashtekar variables. The original version was compiled by Peter Huebner in 1989, and it has been subsequently updated by Gabriela Gonzalez and Bernd Bruegmann. Information about additional literature, new preprints, and especially corrections are always welcome.
|
0911.0802
|
Alfonso Garc\'ia-Parrado G\'omez-Lobo Dr.
|
Piotr T. Chru\'sciel, Julien Cortier and Alfonso Garc\'ia-Parrado
G\'omez-Lobo
|
On the global structure of the Pomeransky-Senkov black holes
|
84 pages, 25 figures. Extension through the Killing horizon in the
degenerate case included, section 2 re-written and references added.
Submitted to Advances in Theoretical and Mathematical Physics
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We construct analytic extensions of the Pomeransky-Senkov metrics with
multiple Killing horizons and asymptotic regions. We show that, in our
extensions, the singularities associated to an obstruction to differentiability
of the metric lie beyond event horizons. We analyze the topology of the
non-empty singular set, which turns out to be parameter-dependent. We present
numerical evidence for stable causality of the domain of outer communications.
The resulting global structure is somewhat reminiscent of that of Kerr
space-time.
|
[
{
"created": "Wed, 4 Nov 2009 17:13:30 GMT",
"version": "v1"
},
{
"created": "Sun, 10 Oct 2010 22:26:21 GMT",
"version": "v2"
}
] |
2010-10-12
|
[
[
"Chruściel",
"Piotr T.",
""
],
[
"Cortier",
"Julien",
""
],
[
"Gómez-Lobo",
"Alfonso García-Parrado",
""
]
] |
We construct analytic extensions of the Pomeransky-Senkov metrics with multiple Killing horizons and asymptotic regions. We show that, in our extensions, the singularities associated to an obstruction to differentiability of the metric lie beyond event horizons. We analyze the topology of the non-empty singular set, which turns out to be parameter-dependent. We present numerical evidence for stable causality of the domain of outer communications. The resulting global structure is somewhat reminiscent of that of Kerr space-time.
|
1802.08682
|
Nils Deppe
|
Nils Deppe, Lawrence E. Kidder, Mark A. Scheel, and Saul A. Teukolsky
|
Critical behavior in 3-d gravitational collapse of massless scalar
fields
|
9 pages, 5 figures, data and scripts for making figs in anc data
|
Phys. Rev. D 99, 024018 (2019)
|
10.1103/PhysRevD.99.024018
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present results from the first study of critical behavior in 3-d
gravitational collapse. The source of the gravitational field is a massless
scalar field. This is a well-studied case for spherically symmetric
gravitational collapse, allowing us to understand the reliability and accuracy
of the simulations. We study both supercritical and subcritical evolutions to
see if one provides more accurate results than the other. We find that even for
non-spherical initial data with 35 percent of the power in the $\ell=2$
spherical harmonic, the critical solution is the same as in spherical symmetry.
|
[
{
"created": "Fri, 23 Feb 2018 18:59:30 GMT",
"version": "v1"
},
{
"created": "Wed, 19 Dec 2018 04:32:42 GMT",
"version": "v2"
}
] |
2019-01-16
|
[
[
"Deppe",
"Nils",
""
],
[
"Kidder",
"Lawrence E.",
""
],
[
"Scheel",
"Mark A.",
""
],
[
"Teukolsky",
"Saul A.",
""
]
] |
We present results from the first study of critical behavior in 3-d gravitational collapse. The source of the gravitational field is a massless scalar field. This is a well-studied case for spherically symmetric gravitational collapse, allowing us to understand the reliability and accuracy of the simulations. We study both supercritical and subcritical evolutions to see if one provides more accurate results than the other. We find that even for non-spherical initial data with 35 percent of the power in the $\ell=2$ spherical harmonic, the critical solution is the same as in spherical symmetry.
|
1307.7372
|
Steven L. Liebling
|
Carlos Palenzuela, Luis Lehner, Steven L. Liebling, Marcelo Ponce,
Matthew Anderson, David Neilsen, Patrick Motl
|
Linking electromagnetic and gravitational radiation in coalescing binary
neutron stars
|
15 pages, 15 figures; Updated with spelling/grammar corrections,
updated references, and better printing figures
|
Phys. Rev. D 88, 043011 (2013)
|
10.1103/PhysRevD.88.043011
| null |
gr-qc astro-ph.HE
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We expand on our study of the gravitational and electromagnetic emissions
from the late stage of an inspiraling neutron star binary as presented in Ref.
\cite{Palenzuela:2013hu}. Interactions between the stellar magnetospheres,
driven by the extreme dynamics of the merger, can yield considerable outflows.
We study the gravitational and electromagnetic waves produced during the
inspiral and merger of a binary neutron star system using a full relativistic,
resistive MHD evolution code. We show that the interaction between the stellar
magnetospheres extracts kinetic energy from the system and powers radiative
Poynting flux and heat dissipation. These features depend strongly on the
configuration of the initial stellar magnetic moments. Our results indicate
that this power can strongly outshine pulsars in binaries and have a
distinctive angular and time-dependent pattern. Our discussion provides more
detail than Ref. \cite{Palenzuela:2013hu}, showing clear evidence of the
different effects taking place during the inspiral. Our simulations include a
few milliseconds after the actual merger and study the dynamics of the magnetic
fields during the formation of the hypermassive neutron star. We also briefly
discuss the possibility of observing such emissions.
|
[
{
"created": "Sun, 28 Jul 2013 14:58:52 GMT",
"version": "v1"
},
{
"created": "Mon, 19 Aug 2013 21:16:51 GMT",
"version": "v2"
}
] |
2013-09-13
|
[
[
"Palenzuela",
"Carlos",
""
],
[
"Lehner",
"Luis",
""
],
[
"Liebling",
"Steven L.",
""
],
[
"Ponce",
"Marcelo",
""
],
[
"Anderson",
"Matthew",
""
],
[
"Neilsen",
"David",
""
],
[
"Motl",
"Patrick",
""
]
] |
We expand on our study of the gravitational and electromagnetic emissions from the late stage of an inspiraling neutron star binary as presented in Ref. \cite{Palenzuela:2013hu}. Interactions between the stellar magnetospheres, driven by the extreme dynamics of the merger, can yield considerable outflows. We study the gravitational and electromagnetic waves produced during the inspiral and merger of a binary neutron star system using a full relativistic, resistive MHD evolution code. We show that the interaction between the stellar magnetospheres extracts kinetic energy from the system and powers radiative Poynting flux and heat dissipation. These features depend strongly on the configuration of the initial stellar magnetic moments. Our results indicate that this power can strongly outshine pulsars in binaries and have a distinctive angular and time-dependent pattern. Our discussion provides more detail than Ref. \cite{Palenzuela:2013hu}, showing clear evidence of the different effects taking place during the inspiral. Our simulations include a few milliseconds after the actual merger and study the dynamics of the magnetic fields during the formation of the hypermassive neutron star. We also briefly discuss the possibility of observing such emissions.
|
1701.06913
|
Behrooz Malekolkalami
|
Ali. Mahmoodzadeh, B. Malakolkalami
|
Geodesics around oscillatons made of exponential scalar field potential
|
12 pages, 12 figures
| null |
10.1007/s10509-018-3389-8
| null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Oscillatons are spherically symmetric solutions to the Einstein Klein Gordon
(EKG) equations for soliton stars made of real time dependent scalar fields.
These equations are non singular and satisfy flatness conditions asymptotically
with periodic time dependency. In this paper, we investigate the geodesic
motion of particles moving around an oscillaton related to a time dependent
scalar field. Bound orbital is found for these particles under the condition of
particular values of angular momentum L and initial radial position. We discuss
this topic for an exponential scalar field potential which could be of the
exponential form with a scalar field and investigate whether the radial
coordinates of such particles oscillate in time or not and thereby we could
predict the corresponding oscillating period as well as amplitude. It is
necessary to recall, in general relativity, a geodesic generalizes the notion
of a straight line to curved space time. Importantly, the world line of a
particle free from all external, non gravitational forces, is a particular type
of geodesic. In other words, a freely moving or falling particle always moves
along a geodesic. In general relativity, gravity can be regarded as not a force
but a consequence of a curved space time geometry where the source of curvature
is the stress energy tensor (representing matter, for instance). Thus, for
example, the path of a planet orbiting around a star is the projection of a
geodesic of the curved 4D space time geometry around the star onto 3D space.
|
[
{
"created": "Sun, 22 Jan 2017 07:23:31 GMT",
"version": "v1"
}
] |
2018-08-08
|
[
[
"Mahmoodzadeh",
"Ali.",
""
],
[
"Malakolkalami",
"B.",
""
]
] |
Oscillatons are spherically symmetric solutions to the Einstein Klein Gordon (EKG) equations for soliton stars made of real time dependent scalar fields. These equations are non singular and satisfy flatness conditions asymptotically with periodic time dependency. In this paper, we investigate the geodesic motion of particles moving around an oscillaton related to a time dependent scalar field. Bound orbital is found for these particles under the condition of particular values of angular momentum L and initial radial position. We discuss this topic for an exponential scalar field potential which could be of the exponential form with a scalar field and investigate whether the radial coordinates of such particles oscillate in time or not and thereby we could predict the corresponding oscillating period as well as amplitude. It is necessary to recall, in general relativity, a geodesic generalizes the notion of a straight line to curved space time. Importantly, the world line of a particle free from all external, non gravitational forces, is a particular type of geodesic. In other words, a freely moving or falling particle always moves along a geodesic. In general relativity, gravity can be regarded as not a force but a consequence of a curved space time geometry where the source of curvature is the stress energy tensor (representing matter, for instance). Thus, for example, the path of a planet orbiting around a star is the projection of a geodesic of the curved 4D space time geometry around the star onto 3D space.
|
gr-qc/9407028
|
Melnikov Vitaly Nikolaevich
|
V. D. Ivashchuk and V. N. Melnikov
|
Billiard Representation for Multidimensional Cosmology with
Multicomponent Perfect Fluid near the Singularity
|
16 pages, LaTex. 4 figures are available upon request (hard copy)
|
Class.Quant.Grav.12:809-826,1995
|
10.1088/0264-9381/12/3/017
|
RGA-CSVR-011/94
|
gr-qc
| null |
The multidimensional cosmological model describing the evolution of $n$
Einstein spaces in the presence of multicomponent perfect fluid is considered.
When certain restrictions on the parameters of the model are imposed, the
dynamics of the model near the singularity is reduced to a billiard on the
$(n-1)$-dimensional Lobachevsky space $H^{n-1}$. The geometrical criterion for
the finiteness of the billiard volume and its compactness is suggested. This
criterion reduces the problem to the problem of illumination of
$(n-2)$-dimensional sphere $S^{n-2}$ by point-like sources. Some generalization
of the considered scheme (including scalar field and quantum generalizations)
are considered.
|
[
{
"created": "Tue, 19 Jul 1994 19:05:20 GMT",
"version": "v1"
},
{
"created": "Thu, 21 Jul 1994 08:55:30 GMT",
"version": "v2"
}
] |
2010-04-06
|
[
[
"Ivashchuk",
"V. D.",
""
],
[
"Melnikov",
"V. N.",
""
]
] |
The multidimensional cosmological model describing the evolution of $n$ Einstein spaces in the presence of multicomponent perfect fluid is considered. When certain restrictions on the parameters of the model are imposed, the dynamics of the model near the singularity is reduced to a billiard on the $(n-1)$-dimensional Lobachevsky space $H^{n-1}$. The geometrical criterion for the finiteness of the billiard volume and its compactness is suggested. This criterion reduces the problem to the problem of illumination of $(n-2)$-dimensional sphere $S^{n-2}$ by point-like sources. Some generalization of the considered scheme (including scalar field and quantum generalizations) are considered.
|
1910.04532
|
Alessandro Fabbri
|
Roberto Balbinot, Alessandro Fabbri, Richard A. Dudley and Paul R.
Anderson
|
Particle Production in the Interiors of Acoustic Black Holes
|
28 pages, 17 figures
|
Phys. Rev. D 100, 105021 (2019)
|
10.1103/PhysRevD.100.105021
| null |
gr-qc cond-mat.quant-gas hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Phonon creation inside the horizons of acoustic black holes is investigated
using two simple toy models. It is shown that, unlike what occurs in the
exterior regions, the spectrum is not thermal. This non-thermality is due to
the anomalous scattering that occurs in the interior regions.
|
[
{
"created": "Thu, 10 Oct 2019 13:02:29 GMT",
"version": "v1"
}
] |
2019-12-03
|
[
[
"Balbinot",
"Roberto",
""
],
[
"Fabbri",
"Alessandro",
""
],
[
"Dudley",
"Richard A.",
""
],
[
"Anderson",
"Paul R.",
""
]
] |
Phonon creation inside the horizons of acoustic black holes is investigated using two simple toy models. It is shown that, unlike what occurs in the exterior regions, the spectrum is not thermal. This non-thermality is due to the anomalous scattering that occurs in the interior regions.
|
gr-qc/0607063
|
Christodoulakis Theodosios
|
T. Christodoulakis and Petros A. Terzis
|
The General Solution of Bianchi Type III Vacuum Cosmology
|
Latex2e, 18 pages, accepted in CQG
|
Class.Quant.Grav. 24 (2007) 875-887
|
10.1088/0264-9381/24/4/008
| null |
gr-qc
| null |
The second order Ordinary Differential Equation which describes the unknown
part of the solution space of some vacuum Bianchi Cosmologies is completely
integrated for Type III, thus obtaining the general solution to Einstein's
Field Equations for this case, with the aid of the sixth Painlev\'{e}
transcendent $P_{VI}$. For particular representations of $P_{VI}$ we obtain the
known Kinnersley two-parameter space-time and a solution of Euclidean
signature. The imposition of the space-time generalization of a "hidden"
symmetry of the generic Type III spatial slice, enables us to retrieve the
two-parameter subfamily without considering the Painlev\'{e} transcendent.
|
[
{
"created": "Mon, 17 Jul 2006 14:19:45 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Dec 2006 14:34:22 GMT",
"version": "v2"
}
] |
2007-05-23
|
[
[
"Christodoulakis",
"T.",
""
],
[
"Terzis",
"Petros A.",
""
]
] |
The second order Ordinary Differential Equation which describes the unknown part of the solution space of some vacuum Bianchi Cosmologies is completely integrated for Type III, thus obtaining the general solution to Einstein's Field Equations for this case, with the aid of the sixth Painlev\'{e} transcendent $P_{VI}$. For particular representations of $P_{VI}$ we obtain the known Kinnersley two-parameter space-time and a solution of Euclidean signature. The imposition of the space-time generalization of a "hidden" symmetry of the generic Type III spatial slice, enables us to retrieve the two-parameter subfamily without considering the Painlev\'{e} transcendent.
|
gr-qc/0005122
|
Yurii V. Dumin
|
Yurii V. Dumin (IZMIRAN, Russ. Acad. Sci.)
|
On the Influence of Einstein-Podolsky-Rosen (EPR) Effect on the
Probability of Domain-Wall Formation during a Cosmological Phase Transition
|
5 pages, LaTex2e, no figures. Report at JENAM-2000
| null | null |
S01-P6
|
gr-qc astro-ph hep-ph quant-ph
| null |
Evading formation of the domain walls in cosmological phase transitions is
one of the key problems to be solved for getting agreement with the observed
large-scale homogeneity of the Universe. The previous attempts to get around
this obstacle led to imposing severe observational constraints on the
parameters of the fields involved. Our aim is to show that yet another way to
overcome the above problem is accounting for EPR effect. Namely, if the scalar
(Higgs) field was presented by a single quantum state at the initial instant of
time, then its reduction during a phase transition at some later instant should
be correlated even at distances exceeding the local cosmological horizon. By
considering a simplest 1D model with Z_2 Higgs field, we demonstrate that EPR
effect really can substantially reduce the probability of spontaneous creation
of the domain walls.
|
[
{
"created": "Mon, 29 May 2000 03:34:39 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Dumin",
"Yurii V.",
"",
"IZMIRAN, Russ. Acad. Sci."
]
] |
Evading formation of the domain walls in cosmological phase transitions is one of the key problems to be solved for getting agreement with the observed large-scale homogeneity of the Universe. The previous attempts to get around this obstacle led to imposing severe observational constraints on the parameters of the fields involved. Our aim is to show that yet another way to overcome the above problem is accounting for EPR effect. Namely, if the scalar (Higgs) field was presented by a single quantum state at the initial instant of time, then its reduction during a phase transition at some later instant should be correlated even at distances exceeding the local cosmological horizon. By considering a simplest 1D model with Z_2 Higgs field, we demonstrate that EPR effect really can substantially reduce the probability of spontaneous creation of the domain walls.
|
2307.15735
|
Rodrigo Panosso Macedo
|
Rodrigo Panosso Macedo
|
Hyperboloidal approach for static spherically symmetric spacetimes: a
didactical introduction and applications in black-hole physics
|
41 pages, 6 figures. Published to Philosophical Transactions A issue:
"At the interface of asymptotics, conformal methods and analysis in general
relativity" --- updated version to include referees suggestions and extend
literature
|
Phil. Trans. R. Soc. A. 382 20230046 (2024)
|
10.1098/rsta.2023.0046
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
This work offers a didactical introduction to the calculations and
geometrical properties of a static, spherically symmetric spacetime foliated by
hyperboloidal time surfaces. We discuss the various degrees of freedom
involved, namely the height function, responsible for introducing the
hyperboloidal time coordinate, and a radial compactification function. A
central outcome is the expression of the Trautman-Bondi mass in terms of the
hyperboloidal metric functions. Moreover, we apply this formalism to a class of
wave equations commonly used in black-hole perturbation theory. Additionally,
we provide a comprehensive derivation of the hyperboloidal minimal gauge,
introducing two alternative approaches within this conceptual framework: the
in-out and out-in strategies. Specifically, we demonstrate that the height
function in the in-out strategy follows from the well-known tortoise coordinate
by changing the sign of the terms that become singular at future null infinity.
Similarly, for the out-in strategy, a sign change also occurs in the tortoise
coordinate's regular terms. We apply the methodology to the following
spacetimes: Singularity-approaching slices in Schwarzschild, higher-dimensional
black holes, black hole with matter halo, and Reissner- Nordstr\"om-de Sitter.
From this heuristic study, we conjecture that the out-in strategy is best
adapted for black hole geometries that account for environmental or effective
quantum effects.
|
[
{
"created": "Fri, 28 Jul 2023 18:00:01 GMT",
"version": "v1"
},
{
"created": "Mon, 15 Jan 2024 10:13:48 GMT",
"version": "v2"
}
] |
2024-01-17
|
[
[
"Macedo",
"Rodrigo Panosso",
""
]
] |
This work offers a didactical introduction to the calculations and geometrical properties of a static, spherically symmetric spacetime foliated by hyperboloidal time surfaces. We discuss the various degrees of freedom involved, namely the height function, responsible for introducing the hyperboloidal time coordinate, and a radial compactification function. A central outcome is the expression of the Trautman-Bondi mass in terms of the hyperboloidal metric functions. Moreover, we apply this formalism to a class of wave equations commonly used in black-hole perturbation theory. Additionally, we provide a comprehensive derivation of the hyperboloidal minimal gauge, introducing two alternative approaches within this conceptual framework: the in-out and out-in strategies. Specifically, we demonstrate that the height function in the in-out strategy follows from the well-known tortoise coordinate by changing the sign of the terms that become singular at future null infinity. Similarly, for the out-in strategy, a sign change also occurs in the tortoise coordinate's regular terms. We apply the methodology to the following spacetimes: Singularity-approaching slices in Schwarzschild, higher-dimensional black holes, black hole with matter halo, and Reissner- Nordstr\"om-de Sitter. From this heuristic study, we conjecture that the out-in strategy is best adapted for black hole geometries that account for environmental or effective quantum effects.
|
1909.08351
|
Ayan Chatterjee
|
Ayan Chatterjee and Amit Ghosh
|
Effective Quantum Theory of Black Hole Horizons
|
15 pages 1 figure
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, we develop an effective quantum theory of black hole horizons
using only the local horizon geometry. On the covariant phase space of the
Holst action admitting Weak Isolated Horizon as an inner boundary, we construct
Hamiltonian charges corresponding to Lorentz symmetries. We show that horizon
area is the Hamiltonian charge corresponding to Lorentz boosts as well as that
for Lorentz rotation which acts on $2$-sphere cross-sections of the horizon.
Using this expression of area as a generator of Lorentz rotation, and the fact
that quantum states residing on the horizon cross-sections carry a
representation of $ISO(2)$, we derive the spectrum of area operator on the
horizon. The eigenstates of this area operator are shown to be labelled by
integers or half integers. The entropy is obtained completely in terms of these
\emph{area quanta} residing on the horizon, and is shown to have exponentially
suppressing corrections to the area law. The formalism is also extended to
non-minimally coupled scalar fields, where the area operator gets modified due
to the value of the scalar field on the horizon.
|
[
{
"created": "Wed, 18 Sep 2019 11:06:46 GMT",
"version": "v1"
}
] |
2019-09-19
|
[
[
"Chatterjee",
"Ayan",
""
],
[
"Ghosh",
"Amit",
""
]
] |
In this paper, we develop an effective quantum theory of black hole horizons using only the local horizon geometry. On the covariant phase space of the Holst action admitting Weak Isolated Horizon as an inner boundary, we construct Hamiltonian charges corresponding to Lorentz symmetries. We show that horizon area is the Hamiltonian charge corresponding to Lorentz boosts as well as that for Lorentz rotation which acts on $2$-sphere cross-sections of the horizon. Using this expression of area as a generator of Lorentz rotation, and the fact that quantum states residing on the horizon cross-sections carry a representation of $ISO(2)$, we derive the spectrum of area operator on the horizon. The eigenstates of this area operator are shown to be labelled by integers or half integers. The entropy is obtained completely in terms of these \emph{area quanta} residing on the horizon, and is shown to have exponentially suppressing corrections to the area law. The formalism is also extended to non-minimally coupled scalar fields, where the area operator gets modified due to the value of the scalar field on the horizon.
|
gr-qc/0202073
|
M. M. Akbar
|
M. M. Akbar, P. D. D'Eath
|
Classical Boundary-value Problem in Riemannian Quantum Gravity and
Self-dual Taub-NUT-(anti)de Sitter Geometries
|
20 pages, 11 figures; Latex; Revised version with important new
results on real infilling solutions and corrections. To appear in Nuclear
Physics B, issue 648 (1,2), pp. 397-416
|
Nucl.Phys. B648 (2003) 397-416
|
10.1016/S0550-3213(02)00971-9
|
DAMTP-2002-26
|
gr-qc hep-th
| null |
The classical boundary-value problem of the Einstein field equations is
studied with an arbitrary cosmological constant, in the case of a compact
($S^{3}$) boundary given a biaxial Bianchi-IX positive-definite three-metric,
specified by two radii $(a,b).$ For the simplest, four-ball, topology of the
manifold with this boundary, the regular classical solutions are found within
the family of Taub-NUT-(anti)de Sitter metrics with self-dual Weyl curvature.
For arbitrary choice of positive radii $(a,b),$ we find that there are three
solutions for the infilling geometry of this type. We obtain exact solutions
for them and for their Euclidean actions. The case of negative cosmological
constant is investigated further. For reasonable squashing of the three-sphere,
all three infilling solutions have real-valued actions which possess a ``cusp
catastrophe'' structure with a non-self-intersecting ``catastrophe manifold''
implying that the dominant contribution comes from the unique real
positive-definite solution on the ball. The positive-definite solution exists
even for larger deformations of the three-sphere, as long as a certain
inequality between $a$ and $b$ holds. The action of this solution is
proportional to $-a^{3}$ for large $a (\sim b)$ and hence larger radii are
favoured. The same boundary-value problem with more complicated interior
topology containing a ``bolt'' is investigated in a forthcoming paper.
|
[
{
"created": "Thu, 21 Feb 2002 20:54:01 GMT",
"version": "v1"
},
{
"created": "Tue, 3 Dec 2002 19:29:00 GMT",
"version": "v2"
}
] |
2009-11-07
|
[
[
"Akbar",
"M. M.",
""
],
[
"D'Eath",
"P. D.",
""
]
] |
The classical boundary-value problem of the Einstein field equations is studied with an arbitrary cosmological constant, in the case of a compact ($S^{3}$) boundary given a biaxial Bianchi-IX positive-definite three-metric, specified by two radii $(a,b).$ For the simplest, four-ball, topology of the manifold with this boundary, the regular classical solutions are found within the family of Taub-NUT-(anti)de Sitter metrics with self-dual Weyl curvature. For arbitrary choice of positive radii $(a,b),$ we find that there are three solutions for the infilling geometry of this type. We obtain exact solutions for them and for their Euclidean actions. The case of negative cosmological constant is investigated further. For reasonable squashing of the three-sphere, all three infilling solutions have real-valued actions which possess a ``cusp catastrophe'' structure with a non-self-intersecting ``catastrophe manifold'' implying that the dominant contribution comes from the unique real positive-definite solution on the ball. The positive-definite solution exists even for larger deformations of the three-sphere, as long as a certain inequality between $a$ and $b$ holds. The action of this solution is proportional to $-a^{3}$ for large $a (\sim b)$ and hence larger radii are favoured. The same boundary-value problem with more complicated interior topology containing a ``bolt'' is investigated in a forthcoming paper.
|
2104.14221
|
Qing-Hua Zhu
|
Zhe Chang and Qing-Hua Zhu
|
The observer-dependent shadow of the Kerr black hole
|
v2: 28 pages, 19 figures, 2 tables, minor revisions
|
JCAP09(2021)003
|
10.1088/1475-7516/2021/09/003
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Motivated by inclination of the Earth's orbit that is not located at galactic
plane for observing the shadow of Sgr A*, we consider the black hole shadow for
arbitrary inclinations and different velocities of observers. A surprising
finding of the study is that rotation axis of a black hole might not be
extracted from its shadow, since the ways of the shadow getting distorted
depend not only on the spin of the black hole, but also velocities of
observers. Namely, appearance of the shadow could be rotated by an angle in
observers' celestial sphere due to the observer in motion. In order to further
confirm this result, a formalism is presented for calculating the shadow in
terms of the velocity perturbations. Besides, we also consider the Earth's
orbit for the shadow of Sgr A* by making use of this formalism.
|
[
{
"created": "Thu, 29 Apr 2021 09:20:16 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Sep 2021 17:18:15 GMT",
"version": "v2"
}
] |
2021-09-07
|
[
[
"Chang",
"Zhe",
""
],
[
"Zhu",
"Qing-Hua",
""
]
] |
Motivated by inclination of the Earth's orbit that is not located at galactic plane for observing the shadow of Sgr A*, we consider the black hole shadow for arbitrary inclinations and different velocities of observers. A surprising finding of the study is that rotation axis of a black hole might not be extracted from its shadow, since the ways of the shadow getting distorted depend not only on the spin of the black hole, but also velocities of observers. Namely, appearance of the shadow could be rotated by an angle in observers' celestial sphere due to the observer in motion. In order to further confirm this result, a formalism is presented for calculating the shadow in terms of the velocity perturbations. Besides, we also consider the Earth's orbit for the shadow of Sgr A* by making use of this formalism.
|
1503.04711
|
Kalin Staykov
|
Kalin V. Staykov, Daniela D. Doneva, Stoytcho S. Yazadjiev, and Kostas
D. Kokkotas
|
Gravitational wave asteroseismology of neutron and strange stars in
$R^2$ gravity
|
10 pages, 4 figures
| null |
10.1103/PhysRevD.92.043009
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study the oscillations of neutron and strange stars in $R^2$ gravity. More
precisely the nonradial $f$-modes are examined and the differences with pure
general relativity are investigated. Using these results we build several
gravitational wave asteroseismology relations. Our goal is to determine up to
what extend these relations are equation of state independent and whether they
deviate enough from general relativity in order to produce an observable
effect. The results show that the differences coming from $R^2$ gravity are up
to 10\% and that will be difficult to be observed in the near future. On the
other hand the small deviations in some of the asteroseismology relations show
that they are not only equation of state independent, but they are also quite
insensitive to the gravitational theory. That is why solving the inverse
problem can give us quite robust estimates of the neutron star parameters.
|
[
{
"created": "Mon, 16 Mar 2015 16:16:19 GMT",
"version": "v1"
}
] |
2015-09-23
|
[
[
"Staykov",
"Kalin V.",
""
],
[
"Doneva",
"Daniela D.",
""
],
[
"Yazadjiev",
"Stoytcho S.",
""
],
[
"Kokkotas",
"Kostas D.",
""
]
] |
We study the oscillations of neutron and strange stars in $R^2$ gravity. More precisely the nonradial $f$-modes are examined and the differences with pure general relativity are investigated. Using these results we build several gravitational wave asteroseismology relations. Our goal is to determine up to what extend these relations are equation of state independent and whether they deviate enough from general relativity in order to produce an observable effect. The results show that the differences coming from $R^2$ gravity are up to 10\% and that will be difficult to be observed in the near future. On the other hand the small deviations in some of the asteroseismology relations show that they are not only equation of state independent, but they are also quite insensitive to the gravitational theory. That is why solving the inverse problem can give us quite robust estimates of the neutron star parameters.
|
2305.19318
|
Subhajit Dandapat Mr.
|
Subhajit Dandapat, Michael Ebersold, Abhimanyu Susobhanan, Prerna
Rana, Achamveedu Gopakumar, Shubhanshu Tiwari, Maria Haney, Hyung Mok Lee,
Neel Kolhe
|
Gravitational Waves from Black-Hole Encounters: Prospects for Ground-
and Galaxy-Based Observatories
|
19 pages, 11 figures, accepted for publication in Phys. Rev. D
| null |
10.1103/PhysRevD.108.024013
| null |
gr-qc astro-ph.GA
|
http://creativecommons.org/licenses/by/4.0/
|
Close hyperbolic encounters of black holes (BHs) generate certain Burst With
Memory (BWM) events in the frequency windows of the operational, planned, and
proposed gravitational wave (GW) observatories. We present detailed
explorations of the detectable parameter space of such events that are relevant
for the LIGO-Virgo-KAGRA and the International Pulsar Timing Array (IPTA)
consortia. The underlying temporally evolving GW polarization states are
adapted from Cho et al. [Phys. Rev. D 98, 024039 (2018)] and therefore
incorporate general relativistic effects up to the third post-Newtonian order.
Further, we provide a prescription to ensure the validity of our waveform
family while describing close encounters. Preliminary investigations reveal
that optimally placed BWM events should be visible to megaparsec distances for
the existing ground-based observatories. In contrast, maturing IPTA datasets
should be able to provide constraints on the occurrences of such hyperbolic
encounters of supermassive BHs to gigaparsec distances.
|
[
{
"created": "Tue, 30 May 2023 18:00:03 GMT",
"version": "v1"
}
] |
2023-07-19
|
[
[
"Dandapat",
"Subhajit",
""
],
[
"Ebersold",
"Michael",
""
],
[
"Susobhanan",
"Abhimanyu",
""
],
[
"Rana",
"Prerna",
""
],
[
"Gopakumar",
"Achamveedu",
""
],
[
"Tiwari",
"Shubhanshu",
""
],
[
"Haney",
"Maria",
""
],
[
"Lee",
"Hyung Mok",
""
],
[
"Kolhe",
"Neel",
""
]
] |
Close hyperbolic encounters of black holes (BHs) generate certain Burst With Memory (BWM) events in the frequency windows of the operational, planned, and proposed gravitational wave (GW) observatories. We present detailed explorations of the detectable parameter space of such events that are relevant for the LIGO-Virgo-KAGRA and the International Pulsar Timing Array (IPTA) consortia. The underlying temporally evolving GW polarization states are adapted from Cho et al. [Phys. Rev. D 98, 024039 (2018)] and therefore incorporate general relativistic effects up to the third post-Newtonian order. Further, we provide a prescription to ensure the validity of our waveform family while describing close encounters. Preliminary investigations reveal that optimally placed BWM events should be visible to megaparsec distances for the existing ground-based observatories. In contrast, maturing IPTA datasets should be able to provide constraints on the occurrences of such hyperbolic encounters of supermassive BHs to gigaparsec distances.
|
2206.04970
|
Alfredo Bautista
|
A. Bautista, A. Ibort, J. Lafuente
|
The sky invariant: A new conformal invariant for Schwarzschild spacetime
|
20 pages, 2 figures, accepted for publication in International
Journal of Geometric Methods in Modern Physics
| null |
10.1142/S0219887822501687
| null |
gr-qc math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A new class of conformal invariants for a given spacetime $M$ is introduced
exploiting the conformal geometry of any light ray $\Gamma$. Each congruence of
light rays passing through a given point $p$ defines the sky $S(p)$ of such
point. The new conformal invariants are defined on the bundle of skies of the
spacetime $M$, being called sky invariants accordingly. The natural conformal
covariant derivative defined on a light ray and its associated covariant
calculus allows us show the existence of a natural conformal invariant
differential of arc that, together with the restriction of the curvature of the
conformal covariant derivative, can be used to construct a sky invariant that
will be called the sky curvature. An algorithm, that can be implemented on any
symbolic manipulation software system, to compute the sky curvature will be
discussed and the main ideas and the explicit computation of the sky curvature
are illustrated in Schwarzschild spacetime.
|
[
{
"created": "Fri, 10 Jun 2022 09:59:47 GMT",
"version": "v1"
}
] |
2022-10-05
|
[
[
"Bautista",
"A.",
""
],
[
"Ibort",
"A.",
""
],
[
"Lafuente",
"J.",
""
]
] |
A new class of conformal invariants for a given spacetime $M$ is introduced exploiting the conformal geometry of any light ray $\Gamma$. Each congruence of light rays passing through a given point $p$ defines the sky $S(p)$ of such point. The new conformal invariants are defined on the bundle of skies of the spacetime $M$, being called sky invariants accordingly. The natural conformal covariant derivative defined on a light ray and its associated covariant calculus allows us show the existence of a natural conformal invariant differential of arc that, together with the restriction of the curvature of the conformal covariant derivative, can be used to construct a sky invariant that will be called the sky curvature. An algorithm, that can be implemented on any symbolic manipulation software system, to compute the sky curvature will be discussed and the main ideas and the explicit computation of the sky curvature are illustrated in Schwarzschild spacetime.
|
gr-qc/0006084
|
Harald P. Pfeiffer
|
Harald P. Pfeiffer, Saul A. Teukolsky, Gregory B. Cook
|
Quasi-circular Orbits for Spinning Binary Black Holes
|
13 pages, 10 figures, submitted to PRD
|
Phys.Rev.D62:104018,2000
|
10.1103/PhysRevD.62.104018
| null |
gr-qc
| null |
Using an effective potential method we examine binary black holes where the
individual holes carry spin. We trace out sequences of quasi-circular orbits
and locate the innermost stable circular orbit as a function of spin. At large
separations, the sequences of quasi-circular orbits match well with
post-Newtonian expansions, although a clear signature of the simplifying
assumption of conformal flatness is seen. The position of the ISCO is found to
be strongly dependent on the magnitude of the spin on each black hole. At close
separations of the holes, the effective potential method breaks down. In all
cases where an ISCO could be determined, we found that an apparent horizon
encompassing both holes forms for separations well inside the ISCO.
Nevertheless, we argue that the formation of a common horizon is still
associated with the breakdown of the effective potential method.
|
[
{
"created": "Thu, 22 Jun 2000 19:37:02 GMT",
"version": "v1"
}
] |
2008-11-26
|
[
[
"Pfeiffer",
"Harald P.",
""
],
[
"Teukolsky",
"Saul A.",
""
],
[
"Cook",
"Gregory B.",
""
]
] |
Using an effective potential method we examine binary black holes where the individual holes carry spin. We trace out sequences of quasi-circular orbits and locate the innermost stable circular orbit as a function of spin. At large separations, the sequences of quasi-circular orbits match well with post-Newtonian expansions, although a clear signature of the simplifying assumption of conformal flatness is seen. The position of the ISCO is found to be strongly dependent on the magnitude of the spin on each black hole. At close separations of the holes, the effective potential method breaks down. In all cases where an ISCO could be determined, we found that an apparent horizon encompassing both holes forms for separations well inside the ISCO. Nevertheless, we argue that the formation of a common horizon is still associated with the breakdown of the effective potential method.
|
2005.08784
|
Celia Escamilla-Rivera
|
Celia Escamilla-Rivera and Hernando Quevedo
|
Quantum signatures from Horava-Lifshitz cosmography
|
15 pages, 2 figures, 3 cables. Version accepted in CQG
|
Class. Quantum Grav. 38 115009 2021
|
10.1088/1361-6382/abf66c
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper we propose an alternative cosmography by considering
Horava-Lifshitz gravity as a model of quantum gravity to search for quantum
effects at the cosmological level. For our analyses we consider current late
universe surveys and a Gravitational Waves forecast from Einstein Telescope. We
found naturally a non-flat scenario with $\Omega_k =-0.021^{+0.023}_{-0.029}$
with $H_0 = 71.904^{+1.406}_{-1.347}$, without showing the standard reported
$3.4$-$\sigma$ inconsistency. Furthermore, we obtained a specific value for the
Ho\v rava parameter $\omega \approx -3.8\times 10^{-14}$, which can be
interpreted as a measure of a quantum effect and could be used to further test
this quantum gravity model. We conclude that classically, according to the
$\Lambda$CDM model, our universe seems to be spatially flat, but in fact, it is
curved from a quantum point of view.
|
[
{
"created": "Fri, 15 May 2020 03:35:50 GMT",
"version": "v1"
},
{
"created": "Wed, 7 Apr 2021 15:44:02 GMT",
"version": "v2"
}
] |
2021-05-07
|
[
[
"Escamilla-Rivera",
"Celia",
""
],
[
"Quevedo",
"Hernando",
""
]
] |
In this paper we propose an alternative cosmography by considering Horava-Lifshitz gravity as a model of quantum gravity to search for quantum effects at the cosmological level. For our analyses we consider current late universe surveys and a Gravitational Waves forecast from Einstein Telescope. We found naturally a non-flat scenario with $\Omega_k =-0.021^{+0.023}_{-0.029}$ with $H_0 = 71.904^{+1.406}_{-1.347}$, without showing the standard reported $3.4$-$\sigma$ inconsistency. Furthermore, we obtained a specific value for the Ho\v rava parameter $\omega \approx -3.8\times 10^{-14}$, which can be interpreted as a measure of a quantum effect and could be used to further test this quantum gravity model. We conclude that classically, according to the $\Lambda$CDM model, our universe seems to be spatially flat, but in fact, it is curved from a quantum point of view.
|
1808.10040
|
Cristian Martinez
|
Luis Avil\'es, Hideki Maeda and Cristian Martinez
|
Exact black-hole formation with a conformally coupled scalar field in
three dimensions
|
47 pages, 6 figures, 7 tables
| null |
10.1088/1361-6382/aaea9f
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present exact dynamical and inhomogeneous solutions in three-dimensional
AdS gravity with a conformally coupled scalar field. They contain stealth
configurations of the scalar field overflying the BTZ spacetime and also
solutions with a non-vanishing energy-momentum tensor. The latter non-stealth
class consists of the solution obtained by Xu and its analytic extension. It is
shown that this proper extension represents: (i) an eternally shrinking
dynamical black hole, (ii) a curious spacetime which admits an event horizon
without any trapped surface, or (iii) gravitational collapse of a scalar field
in an asymptotically AdS spacetime. In the last case, by attaching the solution
regularly to the past massless BTZ spacetime with a vanishing scalar field, the
whole spacetime represents the black-hole formation from regular initial data
in an asymptotically AdS spacetime. Depending on the parameters, the formed
black hole can be asymptotically static in far future.
|
[
{
"created": "Wed, 29 Aug 2018 21:01:19 GMT",
"version": "v1"
}
] |
2018-12-05
|
[
[
"Avilés",
"Luis",
""
],
[
"Maeda",
"Hideki",
""
],
[
"Martinez",
"Cristian",
""
]
] |
We present exact dynamical and inhomogeneous solutions in three-dimensional AdS gravity with a conformally coupled scalar field. They contain stealth configurations of the scalar field overflying the BTZ spacetime and also solutions with a non-vanishing energy-momentum tensor. The latter non-stealth class consists of the solution obtained by Xu and its analytic extension. It is shown that this proper extension represents: (i) an eternally shrinking dynamical black hole, (ii) a curious spacetime which admits an event horizon without any trapped surface, or (iii) gravitational collapse of a scalar field in an asymptotically AdS spacetime. In the last case, by attaching the solution regularly to the past massless BTZ spacetime with a vanishing scalar field, the whole spacetime represents the black-hole formation from regular initial data in an asymptotically AdS spacetime. Depending on the parameters, the formed black hole can be asymptotically static in far future.
|
gr-qc/0608093
|
Juan Guillermo Diaz Ochoa Dr.
|
Juan G. Diaz Ochoa
|
General Relativity at an interface
|
4 Pages
| null | null | null |
gr-qc
| null |
In this work a simple toy model for a free interface between bulk phases in
space and time is presented, derived from the balance equations for extensive
thermodynamic variables of Meinhold-Heerlein. In this case the free interface
represents geodesics in the space-time, allowing the derivation of the
Einstein's equations for gravitational fields. The effect of the balance
equation is examined and a simple expression for cold dark matter is derived.
The thermodynamically meaning of this model is also discussed.
|
[
{
"created": "Sat, 19 Aug 2006 10:05:28 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Ochoa",
"Juan G. Diaz",
""
]
] |
In this work a simple toy model for a free interface between bulk phases in space and time is presented, derived from the balance equations for extensive thermodynamic variables of Meinhold-Heerlein. In this case the free interface represents geodesics in the space-time, allowing the derivation of the Einstein's equations for gravitational fields. The effect of the balance equation is examined and a simple expression for cold dark matter is derived. The thermodynamically meaning of this model is also discussed.
|
1812.11589
|
Markus P\"ossel
|
Markus P\"ossel
|
Relatively complicated? Using models to teach general relativity at
different levels
|
97 pages, 46 figures. Based on an invited talk at the session of the
section Gravitation and Relativity at the Spring Meeting 2017 of the German
Physical Society (DPG) in Bremen, 16 March 2017
| null | null | null |
gr-qc astro-ph.CO physics.ed-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
This review presents an overview of various kinds of models -- physical,
abstract, mathematical, visual -- that can be used to present the concepts and
applications of Einstein's general theory of relativity at the level of
undergraduate and even high-school teaching. After a general introduction
dealing with various kinds of models and their properties, specific areas of
general relativity are addressed: the elastic sheet model and other models for
the fundamental geometric properties of gravity, models for black holes
including the river model, cosmological models for an expanding universe, and
models for gravitational waves as well as for interferometric gravitational
wave detectors.
|
[
{
"created": "Sun, 30 Dec 2018 18:58:17 GMT",
"version": "v1"
}
] |
2019-01-01
|
[
[
"Pössel",
"Markus",
""
]
] |
This review presents an overview of various kinds of models -- physical, abstract, mathematical, visual -- that can be used to present the concepts and applications of Einstein's general theory of relativity at the level of undergraduate and even high-school teaching. After a general introduction dealing with various kinds of models and their properties, specific areas of general relativity are addressed: the elastic sheet model and other models for the fundamental geometric properties of gravity, models for black holes including the river model, cosmological models for an expanding universe, and models for gravitational waves as well as for interferometric gravitational wave detectors.
|
1705.02062
|
Molin Liu
|
Molin Liu, Yingying Shi, Zonghua Zhao and Yu Han
|
New asymptotic Anti-de Sitter solution with a timelike extra dimension
in 5D relativity
|
17 pages, 1 figure, accepted for publication in Annals of Physics
| null |
10.1016/j.aop.2017.05.002
| null |
gr-qc hep-ph hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In 5D relativity, the usual 4D cosmological constant is determined by the
extra dimension. If the extra dimension is spacelike, one can get a positive
cosmological constant $\Lambda$ and a 4D de Sitter (dS) space. In this paper we
present that, if the extra dimension is timelike oppositely, the negative
$\Lambda$ will be emerged and the induced 4D space will be an asymptotic
Anti-de Sitter (AdS). Under the minimum assumption, we solve the Kaluza-Klein
equation $R_{AB} = 0$ in a canonical system and obtain the AdS solution in a
general case. The result shows that an AdS space is induced naturally from a
Kaluza-Klein manifold on a hypersurface (brane). The Lagrangian of test
particle indicates the equation of motion can be geodesics if the 4D metric is
independent of extra dimension. The causality is well respected because it is
appropriately defined by a null higher dimensional interval. In this 5D
relativity, the holographic principle can be used safely because the brane is
asymptotic Euclidean AdS in the bulk. We also explore some possible holographic
duality implications about the field/operator correspondence and the two-points
correlation functions.
|
[
{
"created": "Fri, 5 May 2017 01:54:47 GMT",
"version": "v1"
}
] |
2017-06-07
|
[
[
"Liu",
"Molin",
""
],
[
"Shi",
"Yingying",
""
],
[
"Zhao",
"Zonghua",
""
],
[
"Han",
"Yu",
""
]
] |
In 5D relativity, the usual 4D cosmological constant is determined by the extra dimension. If the extra dimension is spacelike, one can get a positive cosmological constant $\Lambda$ and a 4D de Sitter (dS) space. In this paper we present that, if the extra dimension is timelike oppositely, the negative $\Lambda$ will be emerged and the induced 4D space will be an asymptotic Anti-de Sitter (AdS). Under the minimum assumption, we solve the Kaluza-Klein equation $R_{AB} = 0$ in a canonical system and obtain the AdS solution in a general case. The result shows that an AdS space is induced naturally from a Kaluza-Klein manifold on a hypersurface (brane). The Lagrangian of test particle indicates the equation of motion can be geodesics if the 4D metric is independent of extra dimension. The causality is well respected because it is appropriately defined by a null higher dimensional interval. In this 5D relativity, the holographic principle can be used safely because the brane is asymptotic Euclidean AdS in the bulk. We also explore some possible holographic duality implications about the field/operator correspondence and the two-points correlation functions.
|
2405.00170
|
Leanne Durkan
|
Lorenzo K\"uchler, Geoffrey Comp\`ere, Leanne Durkan, Adam Pound
|
Self-force framework for transition-to-plunge waveforms
|
87 pages, 13 figures
| null | null | null |
gr-qc
|
http://creativecommons.org/licenses/by-nc-sa/4.0/
|
Compact binaries with asymmetric mass ratios are key expected sources for
next-generation gravitational wave detectors. Gravitational self-force theory
has been successful in producing post-adiabatic waveforms that describe the
quasi-circular inspiral around a non-spinning black hole with sub-radian
accuracy, in remarkable agreement with numerical relativity simulations.
Current inspiral models, however, break down at the innermost stable circular
orbit, missing part of the waveform as the secondary body transitions to a
plunge into the black hole. In this work we derive the transition-to-plunge
expansion within a multiscale framework and asymptotically match its early-time
behaviour with the late inspiral. Our multiscale formulation facilitates rapid
generation of waveforms: we build second post-leading transition-to-plunge
waveforms, named 2PLT waveforms. Although our numerical results are limited to
low perturbative orders, our framework contains the analytic tools for building
higher-order waveforms consistent with post-adiabatic inspirals, once all the
necessary numerical self-force data becomes available. We validate our
framework by comparing against numerical relativity simulations, surrogate
models and the effective one-body approach.
|
[
{
"created": "Tue, 30 Apr 2024 19:41:55 GMT",
"version": "v1"
}
] |
2024-05-02
|
[
[
"Küchler",
"Lorenzo",
""
],
[
"Compère",
"Geoffrey",
""
],
[
"Durkan",
"Leanne",
""
],
[
"Pound",
"Adam",
""
]
] |
Compact binaries with asymmetric mass ratios are key expected sources for next-generation gravitational wave detectors. Gravitational self-force theory has been successful in producing post-adiabatic waveforms that describe the quasi-circular inspiral around a non-spinning black hole with sub-radian accuracy, in remarkable agreement with numerical relativity simulations. Current inspiral models, however, break down at the innermost stable circular orbit, missing part of the waveform as the secondary body transitions to a plunge into the black hole. In this work we derive the transition-to-plunge expansion within a multiscale framework and asymptotically match its early-time behaviour with the late inspiral. Our multiscale formulation facilitates rapid generation of waveforms: we build second post-leading transition-to-plunge waveforms, named 2PLT waveforms. Although our numerical results are limited to low perturbative orders, our framework contains the analytic tools for building higher-order waveforms consistent with post-adiabatic inspirals, once all the necessary numerical self-force data becomes available. We validate our framework by comparing against numerical relativity simulations, surrogate models and the effective one-body approach.
|
2005.00831
|
Ion I. Cotaescu
|
Ion I. Cotaescu
|
Time evolution of the free Dirac field in spatially flat FLRW
space-times
|
46 pages no figures
|
Int. J. of Mod. Phys. A Vol. 35, No. 32 (2020) 2030019 (39 pages)
|
10.1142/S0217751X20300197
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The framework of the relativistic quantum mechanics on spatially flat FLRW
space-times is considered for deriving the analytical solutions of the Dirac
equation in different local charts of these manifolds. Systems of commuting
conserved operators are used for determining the fundamental solutions as
common eigenspinors giving thus physical meaning to the integration constants
related to the eigenvalues of these operators. Since these systems, in general,
are incomplete on the FLRW space-times there are integration constants that
must be fixed by setting the vacuum either as the traditional adiabatic one or
as the rest frame vacuum we proposed recently. All the known solutions of the
Dirac equation on these manifolds are discussed in all details and a new type
of spherical waves of given energy in the de Sitter expanding universe is
reported here for the first time.
|
[
{
"created": "Sat, 2 May 2020 13:36:43 GMT",
"version": "v1"
},
{
"created": "Wed, 7 Oct 2020 12:54:16 GMT",
"version": "v2"
},
{
"created": "Thu, 26 Nov 2020 19:42:00 GMT",
"version": "v3"
}
] |
2020-11-30
|
[
[
"Cotaescu",
"Ion I.",
""
]
] |
The framework of the relativistic quantum mechanics on spatially flat FLRW space-times is considered for deriving the analytical solutions of the Dirac equation in different local charts of these manifolds. Systems of commuting conserved operators are used for determining the fundamental solutions as common eigenspinors giving thus physical meaning to the integration constants related to the eigenvalues of these operators. Since these systems, in general, are incomplete on the FLRW space-times there are integration constants that must be fixed by setting the vacuum either as the traditional adiabatic one or as the rest frame vacuum we proposed recently. All the known solutions of the Dirac equation on these manifolds are discussed in all details and a new type of spherical waves of given energy in the de Sitter expanding universe is reported here for the first time.
|
2302.13304
|
Shuxun Tian
|
Shuxun Tian and Shaoqi Hou and Shuo Cao and Zong-Hong Zhu
|
Time evolution of the local gravitational parameters and gravitational
wave polarizations in a relativistic MOND theory
|
9 pages, 3 figures, published in Phys. Rev. D. This version corrects
the footnote citation numbers [48,49,63] in the main text. The PRD published
version also misquotes the relevant citation numbers
|
Phys. Rev. D 107, 044062 (2023)
|
10.1103/PhysRevD.107.044062
| null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
The recently proposed Skordis-Z\l{}o\'{s}nik theory is the first relativistic
MOND theory that can recover the success of the standard $\Lambda$CDM model at
matching observations of the cosmic microwave background. This paper aims to
revisit the Newtonian and MOND approximations and the gravitational wave
analysis of the theory. For the local gravitational parameters, we show that
one could obtain both time-varying effective Newtonian gravitational
\textit{constant} $G_\textrm{N}$ and time-varying characteristic MOND
acceleration scale $a_\textrm{MOND}$, by relaxing the static assumption
extensively adopted in the literature. Specially, we successfully demonstrate
how to reproduce the redshift dependence of $a_\textrm{MOND}$ observed in the
\textit{Magneticum} cold dark matter simulations. For the gravitational waves,
we show that there are only two tensor polarizations, and reconfirm that its
speed is equal to the speed of light.
|
[
{
"created": "Sun, 26 Feb 2023 12:23:41 GMT",
"version": "v1"
},
{
"created": "Wed, 15 Mar 2023 09:31:16 GMT",
"version": "v2"
}
] |
2023-03-16
|
[
[
"Tian",
"Shuxun",
""
],
[
"Hou",
"Shaoqi",
""
],
[
"Cao",
"Shuo",
""
],
[
"Zhu",
"Zong-Hong",
""
]
] |
The recently proposed Skordis-Z\l{}o\'{s}nik theory is the first relativistic MOND theory that can recover the success of the standard $\Lambda$CDM model at matching observations of the cosmic microwave background. This paper aims to revisit the Newtonian and MOND approximations and the gravitational wave analysis of the theory. For the local gravitational parameters, we show that one could obtain both time-varying effective Newtonian gravitational \textit{constant} $G_\textrm{N}$ and time-varying characteristic MOND acceleration scale $a_\textrm{MOND}$, by relaxing the static assumption extensively adopted in the literature. Specially, we successfully demonstrate how to reproduce the redshift dependence of $a_\textrm{MOND}$ observed in the \textit{Magneticum} cold dark matter simulations. For the gravitational waves, we show that there are only two tensor polarizations, and reconfirm that its speed is equal to the speed of light.
|
1401.1506
|
Chad Galley
|
Barry Wardell, Chad R. Galley, Anil Zenginoglu, Marc Casals, Sam R.
Dolan, Adrian C. Ottewill
|
Self-force via Green functions and worldline integration
|
18 pages, 9 figures
|
Phys. Rev. D 89, 084021 (2014)
|
10.1103/PhysRevD.89.084021
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A compact object moving in curved spacetime interacts with its own
gravitational field. This leads to both dissipative and conservative
corrections to the motion, which can be interpreted as a self-force acting on
the object. The original formalism describing this self-force relied heavily on
the Green function of the linear differential operator that governs
gravitational perturbations. However, because the global calculation of Green
functions in non-trivial black hole spacetimes has been an open problem until
recently, alternative methods were established to calculate self-force effects
using sophisticated regularization techniques that avoid the computation of the
global Green function. We present a method for calculating the self-force that
employs the global Green function and is therefore closely modeled after the
original self-force expressions. Our quantitative method involves two stages:
(i) numerical approximation of the retarded Green function in the background
spacetime; (ii) evaluation of convolution integrals along the worldline of the
object. This novel approach can be used along arbitrary worldlines, including
those currently inaccessible to more established computational techniques.
Furthermore, it yields geometrical insight into the contributions to
self-interaction from curved geometry (back-scattering) and trapping of null
geodesics. We demonstrate the method on the motion of a scalar charge in
Schwarzschild spacetime. This toy model retains the physical history-dependence
of the self-force but avoids gauge issues and allows us to focus on basic
principles. We compute the self-field and self-force for many worldlines
including accelerated circular orbits, eccentric orbits at the separatrix, and
radial infall. This method, closely modeled after the original formalism,
provides a promising complementary approach to the self-force problem.
|
[
{
"created": "Tue, 7 Jan 2014 21:00:46 GMT",
"version": "v1"
}
] |
2014-04-23
|
[
[
"Wardell",
"Barry",
""
],
[
"Galley",
"Chad R.",
""
],
[
"Zenginoglu",
"Anil",
""
],
[
"Casals",
"Marc",
""
],
[
"Dolan",
"Sam R.",
""
],
[
"Ottewill",
"Adrian C.",
""
]
] |
A compact object moving in curved spacetime interacts with its own gravitational field. This leads to both dissipative and conservative corrections to the motion, which can be interpreted as a self-force acting on the object. The original formalism describing this self-force relied heavily on the Green function of the linear differential operator that governs gravitational perturbations. However, because the global calculation of Green functions in non-trivial black hole spacetimes has been an open problem until recently, alternative methods were established to calculate self-force effects using sophisticated regularization techniques that avoid the computation of the global Green function. We present a method for calculating the self-force that employs the global Green function and is therefore closely modeled after the original self-force expressions. Our quantitative method involves two stages: (i) numerical approximation of the retarded Green function in the background spacetime; (ii) evaluation of convolution integrals along the worldline of the object. This novel approach can be used along arbitrary worldlines, including those currently inaccessible to more established computational techniques. Furthermore, it yields geometrical insight into the contributions to self-interaction from curved geometry (back-scattering) and trapping of null geodesics. We demonstrate the method on the motion of a scalar charge in Schwarzschild spacetime. This toy model retains the physical history-dependence of the self-force but avoids gauge issues and allows us to focus on basic principles. We compute the self-field and self-force for many worldlines including accelerated circular orbits, eccentric orbits at the separatrix, and radial infall. This method, closely modeled after the original formalism, provides a promising complementary approach to the self-force problem.
|
1512.01934
|
Liu Zhao
|
Xin Hao and Liu Zhao
|
Ricci polynomial gravity
|
12 pages. v5: final version approved for publication in PRD
|
Phys. Rev. D 96, 124034 (2017)
|
10.1103/PhysRevD.96.124034
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study a novel class of higher curvature gravity models in $n$ spacetime
dimensions which we call Ricci polynomial gravity. The action is consisted
purely of a polynomial in Ricci curvature of order $N$. In the absence of the
second order terms in the action, the models are ghost free around the
Minkowski vacuum. By appropriately choosing the coupling coefficients in front
of each terms in the action, it is shown that the models can have multiple
vacua with different effective cosmological constants, and can be made free of
ghost and scalar degrees of freedom around at least one of the maximally
symmetric vacua for any $n>2$ and any $N\geq 4$. We also discuss some of the
physical implications of the existence of multiple vacua in the contexts of
black hole physics and cosmology.
|
[
{
"created": "Mon, 7 Dec 2015 07:39:43 GMT",
"version": "v1"
},
{
"created": "Wed, 9 Dec 2015 07:13:25 GMT",
"version": "v2"
},
{
"created": "Thu, 16 Nov 2017 07:52:09 GMT",
"version": "v3"
},
{
"created": "Mon, 20 Nov 2017 01:19:34 GMT",
"version": "v4"
},
{
"created": "Fri, 8 Dec 2017 08:29:30 GMT",
"version": "v5"
}
] |
2018-01-03
|
[
[
"Hao",
"Xin",
""
],
[
"Zhao",
"Liu",
""
]
] |
We study a novel class of higher curvature gravity models in $n$ spacetime dimensions which we call Ricci polynomial gravity. The action is consisted purely of a polynomial in Ricci curvature of order $N$. In the absence of the second order terms in the action, the models are ghost free around the Minkowski vacuum. By appropriately choosing the coupling coefficients in front of each terms in the action, it is shown that the models can have multiple vacua with different effective cosmological constants, and can be made free of ghost and scalar degrees of freedom around at least one of the maximally symmetric vacua for any $n>2$ and any $N\geq 4$. We also discuss some of the physical implications of the existence of multiple vacua in the contexts of black hole physics and cosmology.
|
2308.09114
|
Omar Valdivia O. Valdivia
|
Luis Avil\'es, Diego Hidalgo and Omar Valdivia
|
Thermodynamics of the three-dimensional black hole with torsion
|
19 pages, comments welcome
| null | null | null |
gr-qc hep-th
|
http://creativecommons.org/licenses/by/4.0/
|
The stationary black hole solution of a Chern-Simons model based on the
semi-simple extension of the Poincar\'e gauge group is studied. The solution
resembles the metric properties of the BTZ geometry but contains, in addition,
non-vanishing torsion. The global structure of spacetime is characterized by
three conserved charges: two associated with the mass and angular momentum and
one extra constant triggered by spacetime torsion. Consequently, we show that
the entropy deviates from the standard Bekenstein-Hawking value and discuss the
implications of torsional charges in the context of black hole thermodynamics.
|
[
{
"created": "Thu, 17 Aug 2023 17:45:01 GMT",
"version": "v1"
}
] |
2023-08-21
|
[
[
"Avilés",
"Luis",
""
],
[
"Hidalgo",
"Diego",
""
],
[
"Valdivia",
"Omar",
""
]
] |
The stationary black hole solution of a Chern-Simons model based on the semi-simple extension of the Poincar\'e gauge group is studied. The solution resembles the metric properties of the BTZ geometry but contains, in addition, non-vanishing torsion. The global structure of spacetime is characterized by three conserved charges: two associated with the mass and angular momentum and one extra constant triggered by spacetime torsion. Consequently, we show that the entropy deviates from the standard Bekenstein-Hawking value and discuss the implications of torsional charges in the context of black hole thermodynamics.
|
1905.09713
|
Mariusz Dabrowski P.
|
Mariusz P. Dabrowski and Fabian Wagner
|
Extended Uncertainty Principle for Rindler and cosmological horizons
|
7 pages, 6 figures, REVTEX 4.1, minor changes, refs updated
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We find exact formulas for the Extended Uncertainty Principle (EUP) for the
Rindler and Friedmann horizons and show that they can be expanded to obtain
asymptotic forms known from the previous literature. We calculate the
corrections to Hawking temperature and Bekenstein entropy of a black hole in
the universe due to Rindler and Friedmann horizons. The effect of the EUP is
similar to the canonical corrections of thermal fluctuations and so it rises
the entropy signalling further loss of information.
|
[
{
"created": "Thu, 23 May 2019 15:18:15 GMT",
"version": "v1"
},
{
"created": "Tue, 28 May 2019 16:00:44 GMT",
"version": "v2"
}
] |
2019-05-29
|
[
[
"Dabrowski",
"Mariusz P.",
""
],
[
"Wagner",
"Fabian",
""
]
] |
We find exact formulas for the Extended Uncertainty Principle (EUP) for the Rindler and Friedmann horizons and show that they can be expanded to obtain asymptotic forms known from the previous literature. We calculate the corrections to Hawking temperature and Bekenstein entropy of a black hole in the universe due to Rindler and Friedmann horizons. The effect of the EUP is similar to the canonical corrections of thermal fluctuations and so it rises the entropy signalling further loss of information.
|
gr-qc/9407002
|
Don N. Page
|
Tomas Kopf, Pavel Krtous, and Don N. Page
|
Too Soon for Doom Gloom?
|
12 pages, LaTeX, Alberta-Thy-17-94
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The observation that we are among the first 10^{11} or so humans reduces the
prior probability that we find ourselves in a species whose total lifetime
number of individuals is much higher, according to arguments of Carter, Leslie,
Nielsen, and Gott. However, if we instead start with a prior probability that a
history has a total lifetime number which is very large, without assuming that
we are in such a history, this more basic probability is not reduced by the
observation of how early in history we exist.
|
[
{
"created": "Mon, 4 Jul 1994 20:28:10 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Dec 2012 19:38:27 GMT",
"version": "v2"
}
] |
2012-12-24
|
[
[
"Kopf",
"Tomas",
""
],
[
"Krtous",
"Pavel",
""
],
[
"Page",
"Don N.",
""
]
] |
The observation that we are among the first 10^{11} or so humans reduces the prior probability that we find ourselves in a species whose total lifetime number of individuals is much higher, according to arguments of Carter, Leslie, Nielsen, and Gott. However, if we instead start with a prior probability that a history has a total lifetime number which is very large, without assuming that we are in such a history, this more basic probability is not reduced by the observation of how early in history we exist.
|
gr-qc/0607036
|
Muhammad Sharif
|
M. Sharif and Tariq Ismaeel
|
Symmetries of the Energy-Momentum Tensor: Some Basic Facts
|
17 pages, accepted for publication in "Communications in Theoretical
Physics"
|
Commun.Theor.Phys.47:829-834,2007
|
10.1088/0253-6102/47/5/013
| null |
gr-qc
| null |
It has been pointed by Hall et al. [1] that matter collinations can be
defined by using three different methods. But there arises the question of
whether one studies matter collineations by using the ${\cal L}_\xi T_{ab}=0$,
or ${\cal L}_\xi T^{ab}=0$ or ${\cal L}_\xi T_a^b=0$. These alternative
conditions are, of course, not generally equivalent. This problem has been
explored by applying these three definitions to general static spherically
symmetric spacetimes. We compare the results with each definition.
|
[
{
"created": "Mon, 10 Jul 2006 10:38:02 GMT",
"version": "v1"
}
] |
2009-03-19
|
[
[
"Sharif",
"M.",
""
],
[
"Ismaeel",
"Tariq",
""
]
] |
It has been pointed by Hall et al. [1] that matter collinations can be defined by using three different methods. But there arises the question of whether one studies matter collineations by using the ${\cal L}_\xi T_{ab}=0$, or ${\cal L}_\xi T^{ab}=0$ or ${\cal L}_\xi T_a^b=0$. These alternative conditions are, of course, not generally equivalent. This problem has been explored by applying these three definitions to general static spherically symmetric spacetimes. We compare the results with each definition.
|
gr-qc/0605143
|
Masoud Alimohammadi
|
H. Mohseni Sadjadi and M. Alimohammadi
|
Transition from quintessence to phantom phase in quintom model
|
LaTeX, 19 pages, four figures, some minor changes in Introduction,
two figures added and the references updated, accepted for publication in
Phys. Rev. D
|
Phys.Rev. D74 (2006) 043506
|
10.1103/PhysRevD.74.043506
| null |
gr-qc astro-ph hep-th
| null |
Assuming the Hubble parameter is a continuous and differentiable function of
comoving time, we investigate necessary conditions for quintessence to phantom
phase transition in quintom model. For power-law and exponential potential
examples, we study the behavior of dynamical dark energy fields and Hubble
parameter near the transition time, and show that the phantom-divide-line w=-1
is crossed in these models.
|
[
{
"created": "Mon, 29 May 2006 08:04:21 GMT",
"version": "v1"
},
{
"created": "Tue, 1 Aug 2006 11:40:39 GMT",
"version": "v2"
}
] |
2009-11-11
|
[
[
"Sadjadi",
"H. Mohseni",
""
],
[
"Alimohammadi",
"M.",
""
]
] |
Assuming the Hubble parameter is a continuous and differentiable function of comoving time, we investigate necessary conditions for quintessence to phantom phase transition in quintom model. For power-law and exponential potential examples, we study the behavior of dynamical dark energy fields and Hubble parameter near the transition time, and show that the phantom-divide-line w=-1 is crossed in these models.
|
0911.3899
|
Barak Kol
|
Shahar Hadar and Barak Kol
|
Post-ISCO Ringdown Amplitudes in Extreme Mass Ratio Inspiral
|
21 pages, 5 figures. v4: added section with numerical evaluation of
the ringdown amplitudes
|
Phys.Rev.D84:044019,2011
|
10.1103/PhysRevD.84.044019
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
An extreme mass ratio inspiral consists of two parts: adiabatic inspiral and
plunge. The plunge trajectory from the innermost stable circular orbit (ISCO)
is special (somewhat independent of initial conditions). We write an expression
for its solution in closed-form and for the emitted waveform. In particular we
extract an expression for the associated black-hole ringdown amplitudes, and
evaluate them numerically.
|
[
{
"created": "Fri, 20 Nov 2009 13:49:32 GMT",
"version": "v1"
},
{
"created": "Sun, 22 Nov 2009 19:20:34 GMT",
"version": "v2"
},
{
"created": "Mon, 7 Dec 2009 12:19:04 GMT",
"version": "v3"
},
{
"created": "Wed, 6 Apr 2011 17:35:39 GMT",
"version": "v4"
}
] |
2015-03-13
|
[
[
"Hadar",
"Shahar",
""
],
[
"Kol",
"Barak",
""
]
] |
An extreme mass ratio inspiral consists of two parts: adiabatic inspiral and plunge. The plunge trajectory from the innermost stable circular orbit (ISCO) is special (somewhat independent of initial conditions). We write an expression for its solution in closed-form and for the emitted waveform. In particular we extract an expression for the associated black-hole ringdown amplitudes, and evaluate them numerically.
|
1903.03430
|
Ritabrata Biswas
|
Amritendu Haldar and Ritabrata Biswas
|
Thermodynamic Studies of Different Black Holes with Modifications of
Entropy
|
15 figures
|
Astrophysics and Space Science 363 (2018)27
|
10.1007/s10509-017-3238-1
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In recent years, the thermodynamic properties of black holes are topics of
interests. We investigate the thermodynamic properties like surface gravity and
Hawking temperature on event horizon of regular black holes viz. {\it Hayward
Class} and {\it asymptotically AdS (Anti-de Sitter)} black holes. We also
analyze the {\it thermodynamic volume} and {\it naive geometric volume} of
asymptotically AdS black holes and show that the entropy of these black holes
is simply the ratio of the naive geometric volume to thermodynamic volume. We
plot the different graphs and interpret them physically. We derive the {\it
`cosmic-Censorship-Inequality'} for both type of black holes. Moreover, we
calculate {\it the thermal heat capacity} of aforesaid black holes and study
their stability in different regimes. Finally, we compute the logarithmic
correction to the entropy for both the black holes considering the quantum
fluctuations around the thermal equilibrium and study the corresponding
thermodynamics.
|
[
{
"created": "Sun, 3 Mar 2019 03:17:34 GMT",
"version": "v1"
}
] |
2019-03-11
|
[
[
"Haldar",
"Amritendu",
""
],
[
"Biswas",
"Ritabrata",
""
]
] |
In recent years, the thermodynamic properties of black holes are topics of interests. We investigate the thermodynamic properties like surface gravity and Hawking temperature on event horizon of regular black holes viz. {\it Hayward Class} and {\it asymptotically AdS (Anti-de Sitter)} black holes. We also analyze the {\it thermodynamic volume} and {\it naive geometric volume} of asymptotically AdS black holes and show that the entropy of these black holes is simply the ratio of the naive geometric volume to thermodynamic volume. We plot the different graphs and interpret them physically. We derive the {\it `cosmic-Censorship-Inequality'} for both type of black holes. Moreover, we calculate {\it the thermal heat capacity} of aforesaid black holes and study their stability in different regimes. Finally, we compute the logarithmic correction to the entropy for both the black holes considering the quantum fluctuations around the thermal equilibrium and study the corresponding thermodynamics.
|
1510.02079
|
Andr\'es Ace\~na
|
Andr\'es Ace\~na and Mar\'ia E. Gabach Cl\'ement
|
Extremal black hole initial data deformations
|
21 pages, no figures, final version
|
Class. Quant. Grav., 33(11):115017, 2016
|
10.1088/0264-9381/33/11/115017
| null |
gr-qc math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study deformations of axially symmetric initial data for Einstein-Maxwell
equations satisfying the time-rotation ($t$-$\phi$) symmetry and containing one
asymptotically cylindrical end and one asymptotically flat end. We find that
the $t$-$\phi$ symmetry implies the existence of a family of deformed data
having the same horizon structure. This result allows us to measure how close
solutions to Lichnerowicz equation are when arising from nearby free data.
|
[
{
"created": "Wed, 7 Oct 2015 19:52:00 GMT",
"version": "v1"
},
{
"created": "Mon, 23 May 2016 20:52:42 GMT",
"version": "v2"
}
] |
2016-05-25
|
[
[
"Aceña",
"Andrés",
""
],
[
"Clément",
"María E. Gabach",
""
]
] |
We study deformations of axially symmetric initial data for Einstein-Maxwell equations satisfying the time-rotation ($t$-$\phi$) symmetry and containing one asymptotically cylindrical end and one asymptotically flat end. We find that the $t$-$\phi$ symmetry implies the existence of a family of deformed data having the same horizon structure. This result allows us to measure how close solutions to Lichnerowicz equation are when arising from nearby free data.
|
2212.10052
|
Wan Cong Ms
|
Piotr T. Chru\'sciel and Wan Cong
|
Characteristic Gluing with $\Lambda$ 1. Linearised Einstein equations on
four-dimensional spacetimes
|
v3: Minor rewordings. Reformatting to match journal version
|
Beijing J. of Pure and Appl. Math., Volume 1, Number 2, 689-796,
2024
| null | null |
gr-qc math-ph math.AP math.DG math.MP
|
http://creativecommons.org/licenses/by/4.0/
|
We establish a gluing theorem for linearised vacuum gravitational fields in
Bondi gauge on a class of characteristic surfaces in static vacuum
four-dimensional backgrounds with cosmological constant $\Lambda \in
\mathbb{R}$ and arbitrary topology of the compact cross-sections of the null
hypersurface. This generalises and complements, in the linearised case, the
pioneering analysis of Aretakis, Czimek and Rodnianski, carried-out on
light-cones in Minkowski spacetime.
|
[
{
"created": "Tue, 20 Dec 2022 07:56:05 GMT",
"version": "v1"
},
{
"created": "Mon, 8 Jan 2024 11:15:09 GMT",
"version": "v2"
},
{
"created": "Fri, 19 Jul 2024 06:39:53 GMT",
"version": "v3"
}
] |
2024-07-22
|
[
[
"Chruściel",
"Piotr T.",
""
],
[
"Cong",
"Wan",
""
]
] |
We establish a gluing theorem for linearised vacuum gravitational fields in Bondi gauge on a class of characteristic surfaces in static vacuum four-dimensional backgrounds with cosmological constant $\Lambda \in \mathbb{R}$ and arbitrary topology of the compact cross-sections of the null hypersurface. This generalises and complements, in the linearised case, the pioneering analysis of Aretakis, Czimek and Rodnianski, carried-out on light-cones in Minkowski spacetime.
|
2205.02431
|
Jie Jiang
|
Ming Zhang and Jie Jiang
|
Generalized Covariant Entropy Bound in Lanczos-Lovelock Gravity
|
7 pages
| null |
10.1103/PhysRevD.106.064002
| null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
In this paper, we investigate the generalized covariant entropy bound in the
theory where the Einstein gravity is perturbed by the higher-order Lovelock
terms. After replacing the Bekenstein-Hawking entropy with the Jacobson-Myers
entropy and introducing two reasonable physical assumptions, we showed that the
corresponding generalized covariant entropy bound is satisfied under a
higher-order approximation of the perturbation from the higher-order Lovelock
terms. Our result implies that the Jacobson-Myers entropy strictly obeys the
entropy bound under the perturbation level, and the generalized second law of
Lanczos-Lovelock gravity is also satisfied when the Einstein gravity is
perturbed by the higher-order Lovelock terms.
|
[
{
"created": "Thu, 5 May 2022 04:19:46 GMT",
"version": "v1"
}
] |
2022-09-14
|
[
[
"Zhang",
"Ming",
""
],
[
"Jiang",
"Jie",
""
]
] |
In this paper, we investigate the generalized covariant entropy bound in the theory where the Einstein gravity is perturbed by the higher-order Lovelock terms. After replacing the Bekenstein-Hawking entropy with the Jacobson-Myers entropy and introducing two reasonable physical assumptions, we showed that the corresponding generalized covariant entropy bound is satisfied under a higher-order approximation of the perturbation from the higher-order Lovelock terms. Our result implies that the Jacobson-Myers entropy strictly obeys the entropy bound under the perturbation level, and the generalized second law of Lanczos-Lovelock gravity is also satisfied when the Einstein gravity is perturbed by the higher-order Lovelock terms.
|
1301.5362
|
Guillermo Chac\'on-Acosta
|
E. Castellanos, G. Chacon-Acosta
|
Polymer Bose--Einstein Condensates
| null | null |
10.1016/j.physletb.2013.04.009
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this work we analyze a non--interacting one dimensional polymer
Bose--Einstein condensate in an harmonic trap within the semiclassical
approximation. We use an effective Hamiltonian coming from the polymer
quantization that arises in loop quantum gravity. We calculate the number of
particles in order to obtain the critical temperature. The Bose--Einstein
functions are replaced by series, whose high order terms are related to powers
of the polymer length. It is shown that the condensation temperature presents a
shift respect to the standard case, for small values of the polymer scale. In
typical experimental conditions, it is possible to establish a bound for
$\lambda^{2}$ up to $ \lesssim 10 ^{-16}$m$^2$. To improve this bound we should
decrease the frequency of the trap and also decrease the number of particles.
|
[
{
"created": "Tue, 22 Jan 2013 23:56:12 GMT",
"version": "v1"
}
] |
2015-06-12
|
[
[
"Castellanos",
"E.",
""
],
[
"Chacon-Acosta",
"G.",
""
]
] |
In this work we analyze a non--interacting one dimensional polymer Bose--Einstein condensate in an harmonic trap within the semiclassical approximation. We use an effective Hamiltonian coming from the polymer quantization that arises in loop quantum gravity. We calculate the number of particles in order to obtain the critical temperature. The Bose--Einstein functions are replaced by series, whose high order terms are related to powers of the polymer length. It is shown that the condensation temperature presents a shift respect to the standard case, for small values of the polymer scale. In typical experimental conditions, it is possible to establish a bound for $\lambda^{2}$ up to $ \lesssim 10 ^{-16}$m$^2$. To improve this bound we should decrease the frequency of the trap and also decrease the number of particles.
|
1203.5030
|
Victor Shchigolev Konstantinovich
|
V. K. Shchigolev, M. P. Rotova
|
Cosmological Model of Interacting Tachyon Field
|
9 pages, 2 figures
|
Mod. Phys. Lett. A, Vol. 27, No. 17 (2012) 1250086
|
10.1142/S0217732312500861
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper we investigate a tachyon field model in cosmology, provided its
interaction with the quintessence or phantom fields.The model takes into
account this interaction beyond the usual approach, in which the interaction is
phenomenologically described by the energy flow between the matter components.
In our model, the interaction of tachyon field with a canonical scalar field is
taken into account through the interaction potential in the total Lagrangian of
the system, like in the case of two or more canonical scalar fields. We obtain
the different types of exact solution for the model by employing the so-called
"first order formalism" procedures.
|
[
{
"created": "Thu, 22 Mar 2012 16:20:44 GMT",
"version": "v1"
}
] |
2012-05-25
|
[
[
"Shchigolev",
"V. K.",
""
],
[
"Rotova",
"M. P.",
""
]
] |
In this paper we investigate a tachyon field model in cosmology, provided its interaction with the quintessence or phantom fields.The model takes into account this interaction beyond the usual approach, in which the interaction is phenomenologically described by the energy flow between the matter components. In our model, the interaction of tachyon field with a canonical scalar field is taken into account through the interaction potential in the total Lagrangian of the system, like in the case of two or more canonical scalar fields. We obtain the different types of exact solution for the model by employing the so-called "first order formalism" procedures.
|
2207.02138
|
Martina Muratore
|
Martina Muratore, Olaf Hartwig, Daniele Vetrugno, Stefano Vitale,
William Joseph Weber
|
On the effectiveness of null TDI channels as instrument noise monitors
in LISA
| null | null | null | null |
gr-qc astro-ph.IM
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present a study of the use and limits of the Time-Delay Interferometry
null channels for in flight estimation of the Laser Interferometer Space
Antenna instrumental noise. The paper considers how the two main limiting noise
sources, test-mass acceleration noise and interferometric phase measurement
noise, propagate through different Time-Delay Interferometry channels: the
Michelson combination X that is the most sensitive to gravitational waves, then
the less-sensitive combinations $\alpha$, and finally the null channel $\zeta$.
We note that the null channel $\zeta$, which is known to be equivalent to any
null channel, not only has a reduced sensitivity to the gravitational waves,
but also feature a larger degree of cancellation of the test mass acceleration
noise relative to the interferometry noise. This severely limits its use in
quantifying the low frequency instrumental noise in the Michelson X
combination, which is expected to be dominated by acceleration noise. However,
we show that one can still use in-flight noise estimations from $\zeta$ to put
an upper bound on the considered noises entering in the X channel, which allows
to distinguish them from a strong stochastic gravitational wave background.
|
[
{
"created": "Tue, 5 Jul 2022 16:02:50 GMT",
"version": "v1"
},
{
"created": "Tue, 2 Aug 2022 14:35:09 GMT",
"version": "v2"
},
{
"created": "Thu, 2 Mar 2023 09:30:14 GMT",
"version": "v3"
}
] |
2023-03-03
|
[
[
"Muratore",
"Martina",
""
],
[
"Hartwig",
"Olaf",
""
],
[
"Vetrugno",
"Daniele",
""
],
[
"Vitale",
"Stefano",
""
],
[
"Weber",
"William Joseph",
""
]
] |
We present a study of the use and limits of the Time-Delay Interferometry null channels for in flight estimation of the Laser Interferometer Space Antenna instrumental noise. The paper considers how the two main limiting noise sources, test-mass acceleration noise and interferometric phase measurement noise, propagate through different Time-Delay Interferometry channels: the Michelson combination X that is the most sensitive to gravitational waves, then the less-sensitive combinations $\alpha$, and finally the null channel $\zeta$. We note that the null channel $\zeta$, which is known to be equivalent to any null channel, not only has a reduced sensitivity to the gravitational waves, but also feature a larger degree of cancellation of the test mass acceleration noise relative to the interferometry noise. This severely limits its use in quantifying the low frequency instrumental noise in the Michelson X combination, which is expected to be dominated by acceleration noise. However, we show that one can still use in-flight noise estimations from $\zeta$ to put an upper bound on the considered noises entering in the X channel, which allows to distinguish them from a strong stochastic gravitational wave background.
|
2311.00131
|
Alexey Golovnev
|
Alexey Golovnev
|
More on the fact that Rastall = GR
|
6 pages; minor additions
|
Annals of Physics 461 (2024) 169580
|
10.1016/j.aop.2023.169580
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Rastall gravity is the same as General Relativity, with a simple algebraic
redefinition of what is called the energy-momentum tensor. Despite it having
been very clearly explained by M. Visser several years go, there are still many
papers claiming big differences between the two formulations of gravitational
equations and trying to use them for problems of physics. When going this way,
the totally ignored task is to explain why the conserved energy-momentum
quantities and the quantities used for other purposes are different from each
other. Moreover, when researchers are using the non-conserved energy density
and pressure for determining the sound speed, it is just inconsistent with the
Rastall gravity. I carefully explain all this, and also show how one could
construct a variational principle for producing equations in the Rastall form.
|
[
{
"created": "Tue, 31 Oct 2023 20:10:01 GMT",
"version": "v1"
},
{
"created": "Thu, 2 Nov 2023 14:17:50 GMT",
"version": "v2"
},
{
"created": "Mon, 18 Dec 2023 08:28:10 GMT",
"version": "v3"
}
] |
2024-07-11
|
[
[
"Golovnev",
"Alexey",
""
]
] |
Rastall gravity is the same as General Relativity, with a simple algebraic redefinition of what is called the energy-momentum tensor. Despite it having been very clearly explained by M. Visser several years go, there are still many papers claiming big differences between the two formulations of gravitational equations and trying to use them for problems of physics. When going this way, the totally ignored task is to explain why the conserved energy-momentum quantities and the quantities used for other purposes are different from each other. Moreover, when researchers are using the non-conserved energy density and pressure for determining the sound speed, it is just inconsistent with the Rastall gravity. I carefully explain all this, and also show how one could construct a variational principle for producing equations in the Rastall form.
|
2201.02016
|
Hassan Firouzjahi
|
Hassan Firouzjahi
|
Cosmological constant problem on the horizon
|
v3: discussions improved, new references added, matches the PRD
version
| null | null | null |
gr-qc astro-ph.CO hep-ph hep-th
|
http://creativecommons.org/licenses/by/4.0/
|
We revisit the quantum cosmological constant problem and highlight the
important roles played by the dS horizon of zero point energy. We argue that
fields which are light enough to have dS horizon of zero point energy
comparable to the FLRW Hubble radius are the main contributors to dark energy.
On the other hand, the zero point energy of heavy fields develop nonlinearities
on sub-Hubble scales and can not contribute to dark energy. We speculate that
our proposal may provide a resolution for both the old and new cosmological
constant problems by noting that there exists a field, the (lightest) neutrino,
which happens to have a mass comparable to the present background photon
temperature. The proposal predicts multiple transient periods of dark energy in
early and late expansion history of the universe yielding to a higher value of
the current Hubble expansion rate which can resolve the $H_0$ tension problem.
|
[
{
"created": "Thu, 6 Jan 2022 11:29:11 GMT",
"version": "v1"
},
{
"created": "Fri, 3 Jun 2022 04:47:34 GMT",
"version": "v2"
},
{
"created": "Thu, 29 Sep 2022 06:41:00 GMT",
"version": "v3"
}
] |
2022-09-30
|
[
[
"Firouzjahi",
"Hassan",
""
]
] |
We revisit the quantum cosmological constant problem and highlight the important roles played by the dS horizon of zero point energy. We argue that fields which are light enough to have dS horizon of zero point energy comparable to the FLRW Hubble radius are the main contributors to dark energy. On the other hand, the zero point energy of heavy fields develop nonlinearities on sub-Hubble scales and can not contribute to dark energy. We speculate that our proposal may provide a resolution for both the old and new cosmological constant problems by noting that there exists a field, the (lightest) neutrino, which happens to have a mass comparable to the present background photon temperature. The proposal predicts multiple transient periods of dark energy in early and late expansion history of the universe yielding to a higher value of the current Hubble expansion rate which can resolve the $H_0$ tension problem.
|
1001.2726
|
Josep M. Pons
|
J. M. Pons, D. C. Salisbury, K. A. Sundermeyer
|
Observables in classical canonical gravity: folklore demystified
|
15 pages, To appear in Proceedings of 1st Mediterranean Conference on
Classical and Quantum Gravity. Corrected minor typos
| null |
10.1088/1742-6596/222/1/012018
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We give an overview of some conceptual difficulties, sometimes called
paradoxes, that have puzzled for years the physical interpetation of classical
canonical gravity and, by extension, the canonical formulation of generally
covariant theories. We identify these difficulties as stemming form some
terminological misunderstandings as to what is meant by "gauge invariance", or
what is understood classically by a "physical state". We make a thorough
analysis of the issue and show that all purported paradoxes disappear when the
right terminology is in place. Since this issue is connected with the search of
observables - gauge invariant quantities - for these theories, we formally show
that time evolving observables can be constructed for every observer. This
construction relies on the fixation of the gauge freedom of diffeomorphism
invariance by means of a scalar coordinatization. We stress the condition that
the coordinatization must be made with scalars. As an example of our method for
obtaining observables we discuss the case of the massive particle in AdS
spacetime.
|
[
{
"created": "Fri, 15 Jan 2010 16:21:25 GMT",
"version": "v1"
},
{
"created": "Wed, 12 May 2010 10:43:14 GMT",
"version": "v2"
}
] |
2015-05-18
|
[
[
"Pons",
"J. M.",
""
],
[
"Salisbury",
"D. C.",
""
],
[
"Sundermeyer",
"K. A.",
""
]
] |
We give an overview of some conceptual difficulties, sometimes called paradoxes, that have puzzled for years the physical interpetation of classical canonical gravity and, by extension, the canonical formulation of generally covariant theories. We identify these difficulties as stemming form some terminological misunderstandings as to what is meant by "gauge invariance", or what is understood classically by a "physical state". We make a thorough analysis of the issue and show that all purported paradoxes disappear when the right terminology is in place. Since this issue is connected with the search of observables - gauge invariant quantities - for these theories, we formally show that time evolving observables can be constructed for every observer. This construction relies on the fixation of the gauge freedom of diffeomorphism invariance by means of a scalar coordinatization. We stress the condition that the coordinatization must be made with scalars. As an example of our method for obtaining observables we discuss the case of the massive particle in AdS spacetime.
|
gr-qc/9303033
| null |
Joseph D. Romano
|
Scalar and Spinor Fields in Signature Changing Spacetimes
|
13 pages (Latex file), UMDGR-93-28
|
Phys.Rev. D47 (1993) 4328-4333
|
10.1103/PhysRevD.47.4328
| null |
gr-qc
| null |
The propagation of scalar and spinor fields in a spacetime whose metric
changes signature is analyzed. Recent work of Dray et al. on particle
production from signature change for a (massless) scalar field is reviewed, and
an attempt is made to extend their analysis to the case of a (massless)
spin-half field. In contrast to their results for a scalar field, it is shown
here---for $SL(2,C)$ spinors---that although there are inequivalent forms of
the Dirac equation that can be used to propagate a spinor in a signature
changing spacetime, none of these forms gives rise to a conserved inner product
on the space of solutions to the field equations.
|
[
{
"created": "Fri, 26 Mar 1993 22:45:00 GMT",
"version": "v1"
}
] |
2009-10-22
|
[
[
"Romano",
"Joseph D.",
""
]
] |
The propagation of scalar and spinor fields in a spacetime whose metric changes signature is analyzed. Recent work of Dray et al. on particle production from signature change for a (massless) scalar field is reviewed, and an attempt is made to extend their analysis to the case of a (massless) spin-half field. In contrast to their results for a scalar field, it is shown here---for $SL(2,C)$ spinors---that although there are inequivalent forms of the Dirac equation that can be used to propagate a spinor in a signature changing spacetime, none of these forms gives rise to a conserved inner product on the space of solutions to the field equations.
|
gr-qc/9408031
| null |
E. I. Guendelman and A. B. Kaganovich
|
Kaluza -- Klein Quantum Cosmology with Primordial Negative Cosmological
Constant
|
5 pages, Latex, BGU-94/17/August-PH
|
Grav.Cosmol. 1 (1995) 103-105
| null | null |
gr-qc
| null |
In many interesting models, including superstring theories, a negative vacuum
energy is predicted. Although this effect is usually regarded as undesirable
from a cosmological point of view, we show that this can be the basis for a new
approach to the cosmology of the early Universe. In the framework of quantum
cosmology (in higher dimensions) when we consider a negative cosmological
constant and matter that could be dust or, alternatively, coherent excitations
of a scalar field, the role of cosmic time can be understood. Then we can
predict the existence of a ``quantum inflationary phase'' for some dimensions
and a simultaneous ``quantum deflationary phase'' for the remaining dimensions.
We discuss how it may be possible to exit from this inflation-compactification
era to a phase with zero cosmological constant which allows a classical
description at late times.
|
[
{
"created": "Thu, 25 Aug 1994 19:52:00 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Guendelman",
"E. I.",
""
],
[
"Kaganovich",
"A. B.",
""
]
] |
In many interesting models, including superstring theories, a negative vacuum energy is predicted. Although this effect is usually regarded as undesirable from a cosmological point of view, we show that this can be the basis for a new approach to the cosmology of the early Universe. In the framework of quantum cosmology (in higher dimensions) when we consider a negative cosmological constant and matter that could be dust or, alternatively, coherent excitations of a scalar field, the role of cosmic time can be understood. Then we can predict the existence of a ``quantum inflationary phase'' for some dimensions and a simultaneous ``quantum deflationary phase'' for the remaining dimensions. We discuss how it may be possible to exit from this inflation-compactification era to a phase with zero cosmological constant which allows a classical description at late times.
|
2402.07951
|
Parth Shah Dr.
|
Pooja Vishwakarma and Parth Shah
|
Qualitative behaviour of higher-curvature gravity with boundary terms
i.e the f(Q) gravity models by dynamical system analysis
|
15 pages, 4 figures (accepted for publication in EPJC)
|
Eur. Phys. J. C 84, 159 (2024)
|
10.1140/epjc/s10052-024-12523-0
| null |
gr-qc hep-th
|
http://creativecommons.org/licenses/by/4.0/
|
The higher-curvature gravity with boundary terms i.e the $f(Q)$ theories,
grounded on non-metricity as a fundamental geometric quantity, exhibit
remarkable efficacy in portraying late-time universe phenomena. The aim is to
delineate constraints on two prevalent models within this framework, namely the
Log-square-root model and the Hyperbolic tangent-power model, by employing the
framework of Big Bang Nucleosynthesis (BBN). The approach involves elucidating
deviations induced by higher-curvature gravity with boundary terms in the
freeze-out temperature ($T_{f}$) concerning its departure from the standard
$\Lambda$CDM evolution. Subsequently, constraints on pertinent model parameters
are established by imposing limitations on $\vert \frac{\delta
T_{f}}{T_{f}}\vert$ derived from observational bounds. This investigation
employs dynamical system analysis, scrutinizing both background and perturbed
equations. The study systematically explores the phase space of the models,
identifying equilibrium points, evaluating their stability, and comprehending
the system's trajectory around each critical point. The principal findings of
this analysis reveal the presence of a matter-dominated saddle point
characterized by the appropriate matter perturbation growth rate. Subsequently,
this phase transitions into a stable phase of a dark-energy-dominated,
accelerating universe, marked by consistent matter perturbations. Overall, the
study substantiates observational confrontations, affirming the potential of
higher-curvature gravity with boundary terms as a promising alternative to the
$\Lambda$CDM concordance model. The methodological approach underscores the
significance of dynamical systems as an independent means to validate and
comprehend the cosmological implications of these theories.
|
[
{
"created": "Sat, 10 Feb 2024 07:15:59 GMT",
"version": "v1"
}
] |
2024-02-20
|
[
[
"Vishwakarma",
"Pooja",
""
],
[
"Shah",
"Parth",
""
]
] |
The higher-curvature gravity with boundary terms i.e the $f(Q)$ theories, grounded on non-metricity as a fundamental geometric quantity, exhibit remarkable efficacy in portraying late-time universe phenomena. The aim is to delineate constraints on two prevalent models within this framework, namely the Log-square-root model and the Hyperbolic tangent-power model, by employing the framework of Big Bang Nucleosynthesis (BBN). The approach involves elucidating deviations induced by higher-curvature gravity with boundary terms in the freeze-out temperature ($T_{f}$) concerning its departure from the standard $\Lambda$CDM evolution. Subsequently, constraints on pertinent model parameters are established by imposing limitations on $\vert \frac{\delta T_{f}}{T_{f}}\vert$ derived from observational bounds. This investigation employs dynamical system analysis, scrutinizing both background and perturbed equations. The study systematically explores the phase space of the models, identifying equilibrium points, evaluating their stability, and comprehending the system's trajectory around each critical point. The principal findings of this analysis reveal the presence of a matter-dominated saddle point characterized by the appropriate matter perturbation growth rate. Subsequently, this phase transitions into a stable phase of a dark-energy-dominated, accelerating universe, marked by consistent matter perturbations. Overall, the study substantiates observational confrontations, affirming the potential of higher-curvature gravity with boundary terms as a promising alternative to the $\Lambda$CDM concordance model. The methodological approach underscores the significance of dynamical systems as an independent means to validate and comprehend the cosmological implications of these theories.
|
gr-qc/0009104
|
A. Heidmann
|
M. Cerdonio, L. Conti, A. Heidmann and M. Pinard
|
Thermoelastic effects at low temperatures and quantum limits in
displacement measurements
|
9 pages, 2 figures
|
Phys.Rev. D63 (2001) 082003
|
10.1103/PhysRevD.63.082003
| null |
gr-qc quant-ph
| null |
The displacement fluctuations of mirrors in optomechanical devices, induced
via thermal expansion by temperature fluctuations due either to thermodynamic
fluctuations or to fluctuations in the photon absorption, can be made smaller
than quantum fluctuations, at the low temperatures, high reflectivities and
high light powers needed to readout displacements at the standard quantum
limit. The result is relevant for the design of quantum limited
gravitational-wave detectors, both "interferometers" and "bars", and for
experiments to study directly mechanical motion in the quantum regime.
|
[
{
"created": "Fri, 29 Sep 2000 17:02:49 GMT",
"version": "v1"
},
{
"created": "Wed, 10 Jan 2001 17:40:08 GMT",
"version": "v2"
}
] |
2009-10-31
|
[
[
"Cerdonio",
"M.",
""
],
[
"Conti",
"L.",
""
],
[
"Heidmann",
"A.",
""
],
[
"Pinard",
"M.",
""
]
] |
The displacement fluctuations of mirrors in optomechanical devices, induced via thermal expansion by temperature fluctuations due either to thermodynamic fluctuations or to fluctuations in the photon absorption, can be made smaller than quantum fluctuations, at the low temperatures, high reflectivities and high light powers needed to readout displacements at the standard quantum limit. The result is relevant for the design of quantum limited gravitational-wave detectors, both "interferometers" and "bars", and for experiments to study directly mechanical motion in the quantum regime.
|
0710.5722
|
Martin Bojowald
|
Martin Bojowald and Rupam Das
|
Canonical Gravity with Fermions
|
17 pages; v2: new discussion of parity, more general non-minimal
coupling, less details of constraint analysis
|
Phys.Rev.D78:064009,2008
|
10.1103/PhysRevD.78.064009
|
IGC-07/10-4, ESI-1957
|
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Canonical gravity in real Ashtekar-Barbero variables is generalized to allow
for fermionic matter. The resulting torsion changes several expressions in
Holst's original vacuum analysis, which are summarized here. This in turn
requires adaptations to the known loop quantization of gravity coupled to
fermions, which is discussed on the basis of the classical analysis. As a
result, parity invariance is not manifestly realized in loop quantum gravity.
|
[
{
"created": "Tue, 30 Oct 2007 18:53:28 GMT",
"version": "v1"
},
{
"created": "Tue, 17 Jun 2008 14:10:24 GMT",
"version": "v2"
}
] |
2008-11-07
|
[
[
"Bojowald",
"Martin",
""
],
[
"Das",
"Rupam",
""
]
] |
Canonical gravity in real Ashtekar-Barbero variables is generalized to allow for fermionic matter. The resulting torsion changes several expressions in Holst's original vacuum analysis, which are summarized here. This in turn requires adaptations to the known loop quantization of gravity coupled to fermions, which is discussed on the basis of the classical analysis. As a result, parity invariance is not manifestly realized in loop quantum gravity.
|
2405.08050
|
Tamal Mukhopadhyay
|
Tamal Mukhopadhyay, Banadipa Chakraborty, Anamika Kotal and Ujjal
Debnath
|
Reconstructions of $f(\mathcal{P})$ and $f(\mathcal{Q})$ gravity models
from $(m,n)$-type Barrow Holographic Dark Energy
| null | null | null | null |
gr-qc astro-ph.CO
|
http://creativecommons.org/licenses/by/4.0/
|
In this work, we have reconstructed the extended $f(\mathcal{P})$ cubic
gravity and symmetric $f(\mathcal{Q})$ teleparallel gravity from $(m,n)$-type
Barrow Holographic Dark Energy (BHDE) and find the unknown functions
$f(\mathcal{P})$ and $f(\mathcal{Q})$ in terms of $\mathcal{P}$ and
$\mathcal{Q}$ by taking the universe to be flat, homogeneous and isotropic. We
then analyzed the behavior and stability of each model for the entire stages of
the evolution of the universe by studying several important parameters such as
the deceleration parameter, equation of state (EoS) parameter $\omega_{DE}$,
square of the speed of sound $v_s^2$. Apart from this, we have studied the
cosmographic behavior by plotting the jerk parameter, snap parameter, and lerk
parameter against the redshift. We have also examined the
$\omega'_{DE}-\omega_{DE}$ phase plane and $(r,s^*)$, $(r,q)$ statefinder
parameters that provide valuable insights into the dynamics of the universe and
the distinctive features of the dark energy. All these analyses pointed out
that our model can produce a universe going through an accelerated expansion
with the quintessence type dark energy.
|
[
{
"created": "Mon, 13 May 2024 16:17:03 GMT",
"version": "v1"
}
] |
2024-05-15
|
[
[
"Mukhopadhyay",
"Tamal",
""
],
[
"Chakraborty",
"Banadipa",
""
],
[
"Kotal",
"Anamika",
""
],
[
"Debnath",
"Ujjal",
""
]
] |
In this work, we have reconstructed the extended $f(\mathcal{P})$ cubic gravity and symmetric $f(\mathcal{Q})$ teleparallel gravity from $(m,n)$-type Barrow Holographic Dark Energy (BHDE) and find the unknown functions $f(\mathcal{P})$ and $f(\mathcal{Q})$ in terms of $\mathcal{P}$ and $\mathcal{Q}$ by taking the universe to be flat, homogeneous and isotropic. We then analyzed the behavior and stability of each model for the entire stages of the evolution of the universe by studying several important parameters such as the deceleration parameter, equation of state (EoS) parameter $\omega_{DE}$, square of the speed of sound $v_s^2$. Apart from this, we have studied the cosmographic behavior by plotting the jerk parameter, snap parameter, and lerk parameter against the redshift. We have also examined the $\omega'_{DE}-\omega_{DE}$ phase plane and $(r,s^*)$, $(r,q)$ statefinder parameters that provide valuable insights into the dynamics of the universe and the distinctive features of the dark energy. All these analyses pointed out that our model can produce a universe going through an accelerated expansion with the quintessence type dark energy.
|
2107.09143
|
Pablo Andr\'es Lizardo Romo
|
Andr\'es Lizardo, Javier Chagoya, C. Ortiz
|
On phenomenological parametrizations for the luminosity distance of
gravitational waves
|
19 pages, 3 figures
| null |
10.1142/S0218271822501097
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The propagation of gravitational waves offers new possibilities for testing
the theory of gravity. Amongst these possibilities there is the luminosity
distance of gravitational waves, $d_{gw}$. It has been proposed to study this
property by means of phenomenological parametrizations, which in this work we
confront to the actual predictions of Einstein-scalar-Gauss-Bonnet gravity,
finding that the simplest parametrization performs better. We propose a novel
parametrization that covers a wider range of models, in particular, within
degenerate higher order scalar-tensor theories of gravity. Also, regarding
model selection from best-fit parameters, we find that even quantities derived
from $d_{gw}$ can lead to inconsistent model selection if they are treated
independently. This highlights that it is essential to perform simultaneous
analysis and include other types of data. We expect our findings to be relevant
for future constraints on modified gravity based on the properties of standard
sirens.
|
[
{
"created": "Mon, 19 Jul 2021 20:34:35 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Oct 2021 18:56:30 GMT",
"version": "v2"
},
{
"created": "Wed, 15 Mar 2023 19:47:13 GMT",
"version": "v3"
}
] |
2023-03-17
|
[
[
"Lizardo",
"Andrés",
""
],
[
"Chagoya",
"Javier",
""
],
[
"Ortiz",
"C.",
""
]
] |
The propagation of gravitational waves offers new possibilities for testing the theory of gravity. Amongst these possibilities there is the luminosity distance of gravitational waves, $d_{gw}$. It has been proposed to study this property by means of phenomenological parametrizations, which in this work we confront to the actual predictions of Einstein-scalar-Gauss-Bonnet gravity, finding that the simplest parametrization performs better. We propose a novel parametrization that covers a wider range of models, in particular, within degenerate higher order scalar-tensor theories of gravity. Also, regarding model selection from best-fit parameters, we find that even quantities derived from $d_{gw}$ can lead to inconsistent model selection if they are treated independently. This highlights that it is essential to perform simultaneous analysis and include other types of data. We expect our findings to be relevant for future constraints on modified gravity based on the properties of standard sirens.
|
1804.03113
|
Marek Szydlowski
|
Aleksander Stachowski, Marek Szydlowski, Krzysztof Urbanowski
|
From quantum unstable systems to the decaying dark energy: Cosmological
implications
|
RevTeX 4-1, 18 pages, 5 figures
|
Advances in High Energy Physics 2018, 7080232 (2018)
|
10.1155/2018/7080232
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We consider a cosmology with decaying metastable dark energy and assume that
a decay process of this metastable dark energy is a quantum decay process. Such
an assumption implies among others that the evolution of the Universe is
irreversible and violates the time reversal symmetry. We show that if to
replace the cosmological time $t$ appearing in the equation describing the
evolution of the Universe by the Hubble cosmological scale time, then we obtain
time dependent $\Lambda (t)$ in the form of the series of even powers of the
Hubble parameter $H$: $\Lambda (t) = \Lambda (H)$. Out special attention is
focused on radioactive like exponential form of the decay process of the dark
energy and on the consequences of this type decay.
|
[
{
"created": "Mon, 9 Apr 2018 17:22:00 GMT",
"version": "v1"
}
] |
2019-09-27
|
[
[
"Stachowski",
"Aleksander",
""
],
[
"Szydlowski",
"Marek",
""
],
[
"Urbanowski",
"Krzysztof",
""
]
] |
We consider a cosmology with decaying metastable dark energy and assume that a decay process of this metastable dark energy is a quantum decay process. Such an assumption implies among others that the evolution of the Universe is irreversible and violates the time reversal symmetry. We show that if to replace the cosmological time $t$ appearing in the equation describing the evolution of the Universe by the Hubble cosmological scale time, then we obtain time dependent $\Lambda (t)$ in the form of the series of even powers of the Hubble parameter $H$: $\Lambda (t) = \Lambda (H)$. Out special attention is focused on radioactive like exponential form of the decay process of the dark energy and on the consequences of this type decay.
|
2006.00761
|
Diego Rubiera-Garcia
|
Merce Guerrero, Gerardo Mora-P\'erez, Gonzalo J. Olmo, Emanuele Orazi,
Diego Rubiera-Garcia
|
Rotating black holes in Eddington-inspired Born-Infeld gravity: an exact
solution
|
17 double column pages, 7 figures, revtex4-1 style
|
JCAP 07 (2020) 058
|
10.1088/1475-7516/2020/07/058
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We find an exact, rotating charged black hole solution within
Eddington-inspired Born-Infeld gravity. To this end we employ a recently
developed correspondence or {\it mapping} between modified gravity models built
as scalars out of contractions of the metric with the Ricci tensor, and
formulated in metric-affine spaces (Ricci-Based Gravity theories) and General
Relativity. This way, starting from the Kerr-Newman solution, we show that this
mapping bring us the axisymmetric solutions of Eddington-inspired Born-Infeld
gravity coupled to a certain model of non-linear electrodynamics. We discuss
the most relevant physical features of the solutions obtained this way, both in
the spherically symmetric limit and in the fully rotating regime. Moreover, we
further elaborate on the potential impact of this important technical progress
for bringing closer the predictions of modified gravity with the astrophysical
observations of compact objects and gravitational wave astronomy.
|
[
{
"created": "Mon, 1 Jun 2020 07:28:24 GMT",
"version": "v1"
}
] |
2021-02-02
|
[
[
"Guerrero",
"Merce",
""
],
[
"Mora-Pérez",
"Gerardo",
""
],
[
"Olmo",
"Gonzalo J.",
""
],
[
"Orazi",
"Emanuele",
""
],
[
"Rubiera-Garcia",
"Diego",
""
]
] |
We find an exact, rotating charged black hole solution within Eddington-inspired Born-Infeld gravity. To this end we employ a recently developed correspondence or {\it mapping} between modified gravity models built as scalars out of contractions of the metric with the Ricci tensor, and formulated in metric-affine spaces (Ricci-Based Gravity theories) and General Relativity. This way, starting from the Kerr-Newman solution, we show that this mapping bring us the axisymmetric solutions of Eddington-inspired Born-Infeld gravity coupled to a certain model of non-linear electrodynamics. We discuss the most relevant physical features of the solutions obtained this way, both in the spherically symmetric limit and in the fully rotating regime. Moreover, we further elaborate on the potential impact of this important technical progress for bringing closer the predictions of modified gravity with the astrophysical observations of compact objects and gravitational wave astronomy.
|
2311.02145
|
Pardyumn Kumar Sahoo
|
Oleksii Sokoliuk, Sneha Pradhan, Alexander Baransky and P.K. Sahoo
|
AdS black hole thermodynamics and microstructures from $f(Q)$
gravitation
|
Fortschr. Phys. published version
|
Fortschr. Phys. 72 (2024), 2300043
|
10.1002/prop.202300043
| null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
The significant properties and phase transition of charged Anti-de Sitter
(AdS) black holes have been extensively studied in a variety of modified
theories of gravity in the presence of numerous matter fields. The goal of our
current research is to investigate the AdS black hole's thermodynamics under
the impact of $f(Q)$ gravity. Additionally, this paper explores the black
hole's local stability and phase structure under the relevant gravity. Besides,
we use Ruppeiner geometry to look into the AdS black hole's microscopic
structure. We have numerically computed the Ricci curvature scalar $R$ to
explain the interactions between the AdS black hole's microscopic particles
under the influence of $f(Q)$ gravity.
|
[
{
"created": "Fri, 3 Nov 2023 17:29:32 GMT",
"version": "v1"
}
] |
2024-01-10
|
[
[
"Sokoliuk",
"Oleksii",
""
],
[
"Pradhan",
"Sneha",
""
],
[
"Baransky",
"Alexander",
""
],
[
"Sahoo",
"P. K.",
""
]
] |
The significant properties and phase transition of charged Anti-de Sitter (AdS) black holes have been extensively studied in a variety of modified theories of gravity in the presence of numerous matter fields. The goal of our current research is to investigate the AdS black hole's thermodynamics under the impact of $f(Q)$ gravity. Additionally, this paper explores the black hole's local stability and phase structure under the relevant gravity. Besides, we use Ruppeiner geometry to look into the AdS black hole's microscopic structure. We have numerically computed the Ricci curvature scalar $R$ to explain the interactions between the AdS black hole's microscopic particles under the influence of $f(Q)$ gravity.
|
0909.2411
|
Hajime Sotani
|
Hajime Sotani
|
Probing Tensor-Vector-Scalar Theory with Gravitational Wave
Asteroseismology
|
Accepted for publication in PRD
|
Phys.Rev.D80:064035,2009
|
10.1103/PhysRevD.80.064035
| null |
gr-qc astro-ph.HE
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In order to examine the gravitational waves emitted from the neutron stars in
the tensor-vector-scalar (TeVeS) theory, we derive the perturbation equations
for relativistic stars, where for simplicity we omit the perturbations of
vector field. That is, we consider the perturbations of scalar and tensor
fields. With this assumption, we find that the axial gravitational waves, which
are corresponding to the oscillations of spacetime ($w$ modes), are independent
from the perturbations of scalar field and the effects of scalar field can be
mounted only via the background properties. Using two different equations of
state, we calculate the complex eigenfrequencies of axial $w$ modes and find
that the dependences of frequencies on the stellar compactness are almost
independent from the adopted equation of state and the parameter in TeVeS.
Additionally, these dependences of frequencies of axial $w$ modes in TeVeS is
obviously different from those expected in the general relativity. Thus the
direct observations of gravitational waves could reveal the gravitational
theory in the strong-field regime.
|
[
{
"created": "Sun, 13 Sep 2009 10:35:03 GMT",
"version": "v1"
}
] |
2010-04-30
|
[
[
"Sotani",
"Hajime",
""
]
] |
In order to examine the gravitational waves emitted from the neutron stars in the tensor-vector-scalar (TeVeS) theory, we derive the perturbation equations for relativistic stars, where for simplicity we omit the perturbations of vector field. That is, we consider the perturbations of scalar and tensor fields. With this assumption, we find that the axial gravitational waves, which are corresponding to the oscillations of spacetime ($w$ modes), are independent from the perturbations of scalar field and the effects of scalar field can be mounted only via the background properties. Using two different equations of state, we calculate the complex eigenfrequencies of axial $w$ modes and find that the dependences of frequencies on the stellar compactness are almost independent from the adopted equation of state and the parameter in TeVeS. Additionally, these dependences of frequencies of axial $w$ modes in TeVeS is obviously different from those expected in the general relativity. Thus the direct observations of gravitational waves could reveal the gravitational theory in the strong-field regime.
|
2004.10620
|
Cheng-Yong Zhang
|
Peng Liu, Chao Niu, Cheng-Yong Zhang
|
Instability of regularized 4D charged Einstein-Gauss-Bonnet de-Sitter
black holes
|
22 pages, 10 figures
|
Chin.Phys.C 45 (2021) 2, 025104
|
10.1088/1674-1137/abcd2d
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We studied the instability of the regularized 4D charged
Einstein-Gauss-Bonnet de-Sitter black holes under charged scalar perturbations.
The unstable modes satisfy the superradiant condition, but not all modes
satisfying the superradiant condition are unstable. The instability occurs when
the cosmological constant is small and the black hole charge is not too large.
The Gauss-Bonnet coupling constant makes the unstable black hole more unstable
when both the black hole charge and cosmological constant are small, and makes
the stable black hole more stable when the black hole charge is large.
|
[
{
"created": "Wed, 22 Apr 2020 15:03:23 GMT",
"version": "v1"
},
{
"created": "Fri, 16 Apr 2021 07:10:48 GMT",
"version": "v2"
},
{
"created": "Fri, 1 Oct 2021 03:05:01 GMT",
"version": "v3"
}
] |
2022-07-27
|
[
[
"Liu",
"Peng",
""
],
[
"Niu",
"Chao",
""
],
[
"Zhang",
"Cheng-Yong",
""
]
] |
We studied the instability of the regularized 4D charged Einstein-Gauss-Bonnet de-Sitter black holes under charged scalar perturbations. The unstable modes satisfy the superradiant condition, but not all modes satisfying the superradiant condition are unstable. The instability occurs when the cosmological constant is small and the black hole charge is not too large. The Gauss-Bonnet coupling constant makes the unstable black hole more unstable when both the black hole charge and cosmological constant are small, and makes the stable black hole more stable when the black hole charge is large.
|
gr-qc/0402112
|
Alejandro Perez
|
Karim Noui and Alejandro Perez
|
Dynamics of loop quantum gravity and spin foam models in three
dimensions
|
To appear in the procedings of the Third International Symposium on
Quantum Theory and Symmetries (QTS3), September 2003
| null |
10.1142/9789812702340_0077
| null |
gr-qc
| null |
We present a rigorous regularization of Rovellis's generalized projection
operator in canonical 2+1 gravity. This work establishes a clear-cut connection
between loop quantum gravity and the spin foam approach in this simplified
setting. The point of view adopted here provides a new perspective to tackle
the problem of dynamics in the physically relevant
3+1 case.
|
[
{
"created": "Wed, 25 Feb 2004 03:42:52 GMT",
"version": "v1"
},
{
"created": "Fri, 19 Mar 2004 21:10:13 GMT",
"version": "v2"
}
] |
2017-08-23
|
[
[
"Noui",
"Karim",
""
],
[
"Perez",
"Alejandro",
""
]
] |
We present a rigorous regularization of Rovellis's generalized projection operator in canonical 2+1 gravity. This work establishes a clear-cut connection between loop quantum gravity and the spin foam approach in this simplified setting. The point of view adopted here provides a new perspective to tackle the problem of dynamics in the physically relevant 3+1 case.
|
1008.4193
|
Tiberiu Harko
|
Tiberiu Harko, Francisco S. N. Lobo
|
f(R,L_m) gravity
|
6 pages, no figures; minor modifications, references added; accepted
for publication in EPJ C
|
Eur.Phys.J.C70:373-379,2010
|
10.1140/epjc/s10052-010-1467-3
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We generalize the $f(R)$ type gravity models by assuming that the
gravitational Lagrangian is given by an arbitrary function of the Ricci scalar
$R$ and of the matter Lagrangian $L_m$. We obtain the gravitational field
equations in the metric formalism, as well as the equations of motion for test
particles, which follow from the covariant divergence of the energy-momentum
tensor. The equations of motion for test particles can also be derived from a
variational principle in the particular case in which the Lagrangian density of
the matter is an arbitrary function of the energy-density of the matter only.
Generally, the motion is non-geodesic, and takes place in the presence of an
extra force orthogonal to the four-velocity. The Newtonian limit of the
equation of motion is also considered, and a procedure for obtaining the
energy-momentum tensor of the matter is presented. The gravitational field
equations and the equations of motion for a particular model in which the
action of the gravitational field has an exponential dependence on the standard
general relativistic Hilbert--Einstein Lagrange density are also derived.
|
[
{
"created": "Wed, 25 Aug 2010 02:59:52 GMT",
"version": "v1"
},
{
"created": "Mon, 4 Oct 2010 05:03:05 GMT",
"version": "v2"
}
] |
2011-02-09
|
[
[
"Harko",
"Tiberiu",
""
],
[
"Lobo",
"Francisco S. N.",
""
]
] |
We generalize the $f(R)$ type gravity models by assuming that the gravitational Lagrangian is given by an arbitrary function of the Ricci scalar $R$ and of the matter Lagrangian $L_m$. We obtain the gravitational field equations in the metric formalism, as well as the equations of motion for test particles, which follow from the covariant divergence of the energy-momentum tensor. The equations of motion for test particles can also be derived from a variational principle in the particular case in which the Lagrangian density of the matter is an arbitrary function of the energy-density of the matter only. Generally, the motion is non-geodesic, and takes place in the presence of an extra force orthogonal to the four-velocity. The Newtonian limit of the equation of motion is also considered, and a procedure for obtaining the energy-momentum tensor of the matter is presented. The gravitational field equations and the equations of motion for a particular model in which the action of the gravitational field has an exponential dependence on the standard general relativistic Hilbert--Einstein Lagrange density are also derived.
|
2306.14966
|
Llibert Arest\'e Sal\'o
|
Llibert Arest\'e Sal\'o, Katy Clough and Pau Figueras
|
Puncture gauge formulation for Einstein-Gauss-Bonnet gravity and
four-derivative scalar-tensor theories in $d+1$ spacetime dimensions
|
Version accepted for publication in PRD
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We develop a modified CCZ4 formulation of the Einstein equations in $d+1$
spacetime dimensions for general relativity plus a Gauss-Bonnet term, as well
as for the most general parity-invariant scalar-tensor theory of gravity up to
four derivatives. We demonstrate well-posedness for both theories and provide
full expressions for their implementation in numerical relativity codes. As a
proof of concept, we study the so-called ``stealth-scalarisation'' induced by
the spin of the remnant black hole after merger. As in previous studies using
alternative gauges we find that the scalarisation occurs too late after merger
to impact on the tensor waveform, unless the parameters are finely tuned.
Naively increasing the coupling to accelerate the growth of the scalar field
risks a breakdown of the effective field theory, and therefore well-posedness,
as the evolution is pushed into the strongly coupled regime. Observation of
such an effect would therefore rely on the detection of the scalar radiation
that is produced during scalarisation. This work provides a basis on which
further studies can be undertaken using codes that employ a moving-punctures
approach to managing singularities in the numerical domain. It is therefore an
important step forward in our ability to analyse modifications of general
relativity in gravitational wave observations.
|
[
{
"created": "Mon, 26 Jun 2023 18:00:14 GMT",
"version": "v1"
},
{
"created": "Tue, 12 Sep 2023 14:55:23 GMT",
"version": "v2"
}
] |
2023-09-13
|
[
[
"Saló",
"Llibert Aresté",
""
],
[
"Clough",
"Katy",
""
],
[
"Figueras",
"Pau",
""
]
] |
We develop a modified CCZ4 formulation of the Einstein equations in $d+1$ spacetime dimensions for general relativity plus a Gauss-Bonnet term, as well as for the most general parity-invariant scalar-tensor theory of gravity up to four derivatives. We demonstrate well-posedness for both theories and provide full expressions for their implementation in numerical relativity codes. As a proof of concept, we study the so-called ``stealth-scalarisation'' induced by the spin of the remnant black hole after merger. As in previous studies using alternative gauges we find that the scalarisation occurs too late after merger to impact on the tensor waveform, unless the parameters are finely tuned. Naively increasing the coupling to accelerate the growth of the scalar field risks a breakdown of the effective field theory, and therefore well-posedness, as the evolution is pushed into the strongly coupled regime. Observation of such an effect would therefore rely on the detection of the scalar radiation that is produced during scalarisation. This work provides a basis on which further studies can be undertaken using codes that employ a moving-punctures approach to managing singularities in the numerical domain. It is therefore an important step forward in our ability to analyse modifications of general relativity in gravitational wave observations.
|
1103.5918
|
Ratbay Myrzakulov
|
P. Tsyba, K. Yerzhanov, K. Esmakhanova, I. Kulnazarov, G. Nugmanova,
R. Myrzakulov
|
Reconstruction of f-essence and fermionic Chaplygin gas models of dark
energy
|
10 pages, typos corrected, new section 4 added, refs added, main
results unchanged
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Recently, it was proposed a new fermionic model of dark energy, the so-called
f-essence. In this work, we explicitly reconstruct the different f-essence
models. In particular, these models include the fermionic Chaplygin gas and the
fermionic generalized Chaplygin gas models of dark energy. We also derive the
equation of state parameter of the selected f-essence models.
|
[
{
"created": "Wed, 30 Mar 2011 13:17:01 GMT",
"version": "v1"
},
{
"created": "Tue, 5 Apr 2011 12:58:05 GMT",
"version": "v2"
}
] |
2011-04-06
|
[
[
"Tsyba",
"P.",
""
],
[
"Yerzhanov",
"K.",
""
],
[
"Esmakhanova",
"K.",
""
],
[
"Kulnazarov",
"I.",
""
],
[
"Nugmanova",
"G.",
""
],
[
"Myrzakulov",
"R.",
""
]
] |
Recently, it was proposed a new fermionic model of dark energy, the so-called f-essence. In this work, we explicitly reconstruct the different f-essence models. In particular, these models include the fermionic Chaplygin gas and the fermionic generalized Chaplygin gas models of dark energy. We also derive the equation of state parameter of the selected f-essence models.
|
gr-qc/0502107
|
Noriko Shiiki
|
Noriko Shiiki, Nobuyuki Sawado
|
Black Hole Skyrmions with Negative Cosmological Constant
|
9 pages, 8 figures. Comments, one figure and two references added, to
appear in Phys. Rev. D
|
Phys.Rev. D71 (2005) 104031
|
10.1103/PhysRevD.71.104031
| null |
gr-qc
| null |
We study spherically symmetric black hole solutions with Skyrme hair in the
Einstein-Skyrme theory with a negative cosmological constant. The dependence of
the skyrmion field configuration on the cosmological constant is examined. The
stability is investigated in detail by solving the linearly perturbed equation
numerically. It is shown that there exist linearly stable solutions in the
branch which represents unstable configuration in the asymptotically flat
spacetime.
|
[
{
"created": "Fri, 25 Feb 2005 07:27:29 GMT",
"version": "v1"
},
{
"created": "Sun, 8 May 2005 06:32:21 GMT",
"version": "v2"
}
] |
2009-11-11
|
[
[
"Shiiki",
"Noriko",
""
],
[
"Sawado",
"Nobuyuki",
""
]
] |
We study spherically symmetric black hole solutions with Skyrme hair in the Einstein-Skyrme theory with a negative cosmological constant. The dependence of the skyrmion field configuration on the cosmological constant is examined. The stability is investigated in detail by solving the linearly perturbed equation numerically. It is shown that there exist linearly stable solutions in the branch which represents unstable configuration in the asymptotically flat spacetime.
|
gr-qc/0610052
|
Joseph Katz
|
Joseph Katz, Donald Lynden-Bell and Jiri Bicak
|
Gravitational energy in stationary spacetimes
|
Accepted for publication in Class. Quantum Grav
|
Class.Quant.Grav. 23 (2006) 7111-7128
|
10.1088/0264-9381/23/23/030
| null |
gr-qc
| null |
Static observers remain on Killing-vector world lines and measure the
rest-mass+kinetic energies of particles moving past them, and the flux of that
mechanical energy through space and time. The total mechanical energy is the
total flux through a spacelike cut at one time. The difference between the
total mass-energy and the total mechanical energy is the total gravitational
energy, which we prove to be negative for certain classes of systems. For
spherical systems, Misner, Thorne and Wheeler define the total gravitational
energy this way.
To obtain the gravitational energy density analogous to that of
electromagnetism we first use Einstein's equations with integrations by parts
to remove second order derivatives. Next we apply a conformal transformation to
reexpress the scalar 3-curvature of the 3-space. The resulting density is
non-local.
We repeat the argument for mechanical energies as measured by stationary
observers moving orthogonally to constant time slices like the "zero angular
momentum" observers of Bardeen who exist even within ergospheres.
|
[
{
"created": "Wed, 11 Oct 2006 10:01:16 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Katz",
"Joseph",
""
],
[
"Lynden-Bell",
"Donald",
""
],
[
"Bicak",
"Jiri",
""
]
] |
Static observers remain on Killing-vector world lines and measure the rest-mass+kinetic energies of particles moving past them, and the flux of that mechanical energy through space and time. The total mechanical energy is the total flux through a spacelike cut at one time. The difference between the total mass-energy and the total mechanical energy is the total gravitational energy, which we prove to be negative for certain classes of systems. For spherical systems, Misner, Thorne and Wheeler define the total gravitational energy this way. To obtain the gravitational energy density analogous to that of electromagnetism we first use Einstein's equations with integrations by parts to remove second order derivatives. Next we apply a conformal transformation to reexpress the scalar 3-curvature of the 3-space. The resulting density is non-local. We repeat the argument for mechanical energies as measured by stationary observers moving orthogonally to constant time slices like the "zero angular momentum" observers of Bardeen who exist even within ergospheres.
|
gr-qc/9707030
|
Ioan Vancea
|
Ion V. Vancea
|
Observables of the Euclidean Supergravity
|
Revised version, some misprints in the ecuations (11), (13) and (17)
corrected. The errors in the published version will appear cortected in a
future erratum
|
Phys.Rev.Lett. 79 (1997) 3121-3124; Erratum-ibid. 80 (1998) 1355
|
10.1103/PhysRevLett.79.3121
|
Phys. Rev. Lett. 79, 3121 (1997)
|
gr-qc hep-th
| null |
The set of constraints under which the eigenvalues of the Dirac operator can
play the role of the dynamical variables for Euclidean supergravity is derived.
These constraints arise when the gauge invariance of the eigenvalues of the
Dirac operator is imposed. They impose conditions which restrict the
eigenspinors of the Dirac operator.
|
[
{
"created": "Mon, 14 Jul 1997 13:44:18 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Jul 1997 16:43:07 GMT",
"version": "v2"
},
{
"created": "Tue, 9 Sep 1997 19:49:03 GMT",
"version": "v3"
},
{
"created": "Fri, 24 Oct 1997 11:02:23 GMT",
"version": "v4"
},
{
"created": "Sat, 13 Dec 1997 14:05:23 GMT",
"version": "v5"
}
] |
2009-10-30
|
[
[
"Vancea",
"Ion V.",
""
]
] |
The set of constraints under which the eigenvalues of the Dirac operator can play the role of the dynamical variables for Euclidean supergravity is derived. These constraints arise when the gauge invariance of the eigenvalues of the Dirac operator is imposed. They impose conditions which restrict the eigenspinors of the Dirac operator.
|
1210.7354
|
Mehran Kamarpour
|
Mehran Kamarpour
|
Non-gaussianity in axion N-flation models Quadratic and $\lambda\phi^4$
plus axion potentials
|
28 pages,2 tables
| null | null | null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper we investigate large non-gaussianity in axion N-flation models,
taking account while dynamically a large number of axions begin away from the
hilltop region(come down from the hill) and so serve only to be the source of
the Hubble rate. Therefore the single field stays closest to the hilltop
sources the non-Gaussianity. In this case most of axions can be replaced by a
single effective field with a quadratic potential. So our potential will
contain two fields. The full cosine is responsible for the axion closest to
hilltop and quadratic term which is a source for Hubble rate [4]. We obtain
power spectrum, spectral index and non-gaussianity parameter, then we impose
conditions from WMAP for power spectrum and spectral index and see how large on
non-gaussianity parameter it is possible to achieve with such conditions.
Finally we swap quadratic term to {\lambda}{\phi}^4 and see whether this makes
it harder or easier to achieve large non-gaussianity.We find large
non-gaussianity is achievable by imposing data from WMAP conditional on axion
decay constant f has reasonable value in connection with Planck mass and by
requiring number of e-folds must be bounded between 40-60.When we swap to
{\lambda}{\phi}^4 we find that it is harder to achieve non-Gaussianity, because
we are imposed to investigate only {\lambda}{\phi}^4 domination in consistency
with WMAP data for spectral index. Although, in this case we find that large
non-gaussianity is still achievable. Finally we verify imposing the condition
for spectral index to be nearly one and find acceptable and detectable value
for non-gaussianity typically of order of 10 and 100 depending on value of
decay constant f.Swapping to {\lambda}{\phi}^4 in this case does not give us
any significant relation. In this paper we consider models which can generate
large non-gaussianity. We restrict ourselves to axion N-flation models.
|
[
{
"created": "Sat, 27 Oct 2012 18:20:03 GMT",
"version": "v1"
}
] |
2012-10-30
|
[
[
"Kamarpour",
"Mehran",
""
]
] |
In this paper we investigate large non-gaussianity in axion N-flation models, taking account while dynamically a large number of axions begin away from the hilltop region(come down from the hill) and so serve only to be the source of the Hubble rate. Therefore the single field stays closest to the hilltop sources the non-Gaussianity. In this case most of axions can be replaced by a single effective field with a quadratic potential. So our potential will contain two fields. The full cosine is responsible for the axion closest to hilltop and quadratic term which is a source for Hubble rate [4]. We obtain power spectrum, spectral index and non-gaussianity parameter, then we impose conditions from WMAP for power spectrum and spectral index and see how large on non-gaussianity parameter it is possible to achieve with such conditions. Finally we swap quadratic term to {\lambda}{\phi}^4 and see whether this makes it harder or easier to achieve large non-gaussianity.We find large non-gaussianity is achievable by imposing data from WMAP conditional on axion decay constant f has reasonable value in connection with Planck mass and by requiring number of e-folds must be bounded between 40-60.When we swap to {\lambda}{\phi}^4 we find that it is harder to achieve non-Gaussianity, because we are imposed to investigate only {\lambda}{\phi}^4 domination in consistency with WMAP data for spectral index. Although, in this case we find that large non-gaussianity is still achievable. Finally we verify imposing the condition for spectral index to be nearly one and find acceptable and detectable value for non-gaussianity typically of order of 10 and 100 depending on value of decay constant f.Swapping to {\lambda}{\phi}^4 in this case does not give us any significant relation. In this paper we consider models which can generate large non-gaussianity. We restrict ourselves to axion N-flation models.
|
gr-qc/0504030
|
Rajeev Bhalerao
|
Budh Ram, Arun Ram, Nilam Ram
|
The quantum black hole
|
13 pages, no figs. v2: minor typos corrected. conclusions unchanged
| null | null | null |
gr-qc astro-ph quant-ph
| null |
The quantum nature of a black hole is revealed using the simplest terms that
one learns in undergraduate and beginning graduate courses. The exposition
demonstrates -- vividly -- the importance and power of the quantum oscillator
in contemporary research in theoretical physics.
|
[
{
"created": "Thu, 7 Apr 2005 14:17:53 GMT",
"version": "v1"
},
{
"created": "Wed, 28 Dec 2005 08:58:26 GMT",
"version": "v2"
}
] |
2007-05-23
|
[
[
"Ram",
"Budh",
""
],
[
"Ram",
"Arun",
""
],
[
"Ram",
"Nilam",
""
]
] |
The quantum nature of a black hole is revealed using the simplest terms that one learns in undergraduate and beginning graduate courses. The exposition demonstrates -- vividly -- the importance and power of the quantum oscillator in contemporary research in theoretical physics.
|
1607.08533
|
Antonio Enea Romano
|
Antonio Enea Romano
|
General background conditions for K-bounce and adiabaticity
|
17 pages, 11 figures, version accepted for publication
|
Eur.Phys.J. C77 (2017) no.3, 147
|
10.1140/epjc/s10052-017-4698-8
| null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study the background conditions for a bounce uniquely driven by a single
scalar field model with a generalized kinetic term $K(X)$, without any
additional matter field. At the background level we impose the existence of two
turning points where the derivative of the Hubble parameter $H$ changes sign
and of a bounce point where the Hubble parameter vanishes. We find the
conditions for $K(X)$ and the potential which ensure the above requirements. We
then give the examples of two models constructed according to these conditions.
One is based on a quadratic $K(X)$, and the other a $K(X)$ which is avoiding
divergences of the second time derivative of the scalar field, which may
otherwise occur. An appropriate choice of the initial conditions can lead to a
sequence of consecutive bounces, or oscillations of $H$. In the region where
these models have a constant potential they are adiabatic on any scale and
because of this they may not conserve curvature perturbations on super-horizon
scales. While at the perturbation level one class of models is free from ghosts
and singularities of the classical equations of motion, in general gradient
instabilities are present around the bounce time, because the sign of the
squared speed of sound is opposite to the sign of the time derivative of $H$.
We discuss how this kind of instabilities could be avoided by modifying the
Lagrangian by introducing Galileion terms in order to prevent a negative
squared speed of sound around the bounce.
|
[
{
"created": "Thu, 28 Jul 2016 16:54:39 GMT",
"version": "v1"
},
{
"created": "Fri, 9 Dec 2016 18:26:29 GMT",
"version": "v2"
},
{
"created": "Wed, 15 Mar 2017 02:06:07 GMT",
"version": "v3"
}
] |
2017-03-16
|
[
[
"Romano",
"Antonio Enea",
""
]
] |
We study the background conditions for a bounce uniquely driven by a single scalar field model with a generalized kinetic term $K(X)$, without any additional matter field. At the background level we impose the existence of two turning points where the derivative of the Hubble parameter $H$ changes sign and of a bounce point where the Hubble parameter vanishes. We find the conditions for $K(X)$ and the potential which ensure the above requirements. We then give the examples of two models constructed according to these conditions. One is based on a quadratic $K(X)$, and the other a $K(X)$ which is avoiding divergences of the second time derivative of the scalar field, which may otherwise occur. An appropriate choice of the initial conditions can lead to a sequence of consecutive bounces, or oscillations of $H$. In the region where these models have a constant potential they are adiabatic on any scale and because of this they may not conserve curvature perturbations on super-horizon scales. While at the perturbation level one class of models is free from ghosts and singularities of the classical equations of motion, in general gradient instabilities are present around the bounce time, because the sign of the squared speed of sound is opposite to the sign of the time derivative of $H$. We discuss how this kind of instabilities could be avoided by modifying the Lagrangian by introducing Galileion terms in order to prevent a negative squared speed of sound around the bounce.
|
0709.2041
|
Shahar Hod
|
Shahar Hod
|
A note on the quantization of a multi-horizon black hole
|
6 pages
|
Class.Quant.Grav.24:4871-4874,2007
|
10.1088/0264-9381/24/18/N01
| null |
gr-qc astro-ph hep-th
| null |
We consider the quasinormal spectrum of a charged scalar field in the
(charged) Reissner-Nordstrom spacetime, which has two horizons. The spectrum is
characterized by two distinct families of asymptotic resonances. We suggest and
demonstrate the according to Bohr's correspondence principle and in agreement
with the Bekenstein-Mukhanov quantization scheme, one of these resonances
corresponds to a fundamental change of Delta A=4hbar ln2 in the surface area of
the black-hole outer horizon. The second asymptotic resonance is associated
with a fundamental change of Delta Atot=4hbar ln3 in the total area of the
black hole (in the sum of the surface areas of the inner and outer horizons),
in accordance with a suggestion of Makela and Repo.
|
[
{
"created": "Thu, 13 Sep 2007 10:59:58 GMT",
"version": "v1"
}
] |
2010-10-27
|
[
[
"Hod",
"Shahar",
""
]
] |
We consider the quasinormal spectrum of a charged scalar field in the (charged) Reissner-Nordstrom spacetime, which has two horizons. The spectrum is characterized by two distinct families of asymptotic resonances. We suggest and demonstrate the according to Bohr's correspondence principle and in agreement with the Bekenstein-Mukhanov quantization scheme, one of these resonances corresponds to a fundamental change of Delta A=4hbar ln2 in the surface area of the black-hole outer horizon. The second asymptotic resonance is associated with a fundamental change of Delta Atot=4hbar ln3 in the total area of the black hole (in the sum of the surface areas of the inner and outer horizons), in accordance with a suggestion of Makela and Repo.
|
1701.02381
|
Sebasti\'an Bahamonde
|
Sebastian Bahamonde, Sergei D. Odintsov, V.K. Oikonomou, Petr
V.Tretyakov
|
Deceleration versus Acceleration Universe in Different Frames of $F(R)$
Gravity
|
To appear in Physics Letters B. Some corrections added
| null |
10.1016/j.physletb.2017.01.012
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper we study the occurrence of accelerating universe versus
decelerating universe between the F(R) gravity frame (Jordan frame) and
non-minimally coupled scalar field theory frame, and the minimally coupled
scalar field theory frame (Einstein frame) for various models. As we show, if
acceleration is imposed in one frame, it will not necessarily correspond to an
accelerating metric when transformed in another frame. As we will demonstrate,
this issue is model and frame-dependent but it seems there is no general scheme
which permits to classify such cases.
|
[
{
"created": "Mon, 9 Jan 2017 22:43:34 GMT",
"version": "v1"
},
{
"created": "Sun, 15 Jan 2017 13:37:29 GMT",
"version": "v2"
}
] |
2017-01-17
|
[
[
"Bahamonde",
"Sebastian",
""
],
[
"Odintsov",
"Sergei D.",
""
],
[
"Oikonomou",
"V. K.",
""
],
[
"Tretyakov",
"Petr V.",
""
]
] |
In this paper we study the occurrence of accelerating universe versus decelerating universe between the F(R) gravity frame (Jordan frame) and non-minimally coupled scalar field theory frame, and the minimally coupled scalar field theory frame (Einstein frame) for various models. As we show, if acceleration is imposed in one frame, it will not necessarily correspond to an accelerating metric when transformed in another frame. As we will demonstrate, this issue is model and frame-dependent but it seems there is no general scheme which permits to classify such cases.
|
0805.1160
|
Thomas Sotiriou
|
Thomas P. Sotiriou
|
The viability of theories with matter coupled to the Ricci scalar
|
typos corrected, published version
|
Phys.Lett.B664:225-228,2008
|
10.1016/j.physletb.2008.05.050
| null |
gr-qc astro-ph hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Recently there has been a proposal for modified gravitational f(R) actions
which include a direct coupling between the matter action and the Ricci scalar,
R. Of particular interest is the specific case where both the action and the
coupling are linear in R. It is shown that such an action leads to a theory of
gravity which includes higher order derivatives of the matter fields without
introducing more dynamics in the gravity sector and, therefore, cannot be a
viable theory for gravitation.
|
[
{
"created": "Thu, 8 May 2008 19:53:33 GMT",
"version": "v1"
},
{
"created": "Wed, 11 Jun 2008 16:58:31 GMT",
"version": "v2"
}
] |
2008-11-26
|
[
[
"Sotiriou",
"Thomas P.",
""
]
] |
Recently there has been a proposal for modified gravitational f(R) actions which include a direct coupling between the matter action and the Ricci scalar, R. Of particular interest is the specific case where both the action and the coupling are linear in R. It is shown that such an action leads to a theory of gravity which includes higher order derivatives of the matter fields without introducing more dynamics in the gravity sector and, therefore, cannot be a viable theory for gravitation.
|
1803.04632
|
Hyeong-Chan Kim
|
Hyeong-Chan Kim
|
Growth of a Black Hole on a Self-Gravitating Radiation
|
title changed, 6 pages, no figures
| null |
10.1140/epjc/s10052-018-6487-4
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We feed a black hole on a self-gravitating radiation and observe what happens
during the process. Considering a spherical shell of radiation, we show that
the contribution of self-gravity makes the thermodynamic interaction through
the bottom of the shell be distinguished from thermodynamic interaction through
its top. The growth of a black hole horizon appears to be a sudden jump rather
than a sequential increase. We additionally show that much of the entropy will
be absorbed into the black hole only at the last moment of the collapse.
|
[
{
"created": "Tue, 13 Mar 2018 05:50:49 GMT",
"version": "v1"
},
{
"created": "Wed, 2 May 2018 00:26:51 GMT",
"version": "v2"
}
] |
2018-12-26
|
[
[
"Kim",
"Hyeong-Chan",
""
]
] |
We feed a black hole on a self-gravitating radiation and observe what happens during the process. Considering a spherical shell of radiation, we show that the contribution of self-gravity makes the thermodynamic interaction through the bottom of the shell be distinguished from thermodynamic interaction through its top. The growth of a black hole horizon appears to be a sudden jump rather than a sequential increase. We additionally show that much of the entropy will be absorbed into the black hole only at the last moment of the collapse.
|
gr-qc/9210007
|
Arley Anderson
|
Arlen Anderson
|
Unitary Equivalence of the Metric and Holonomy Formulations of 2+1
Dimensional Quantum Gravity on the Torus
|
31 pages LaTeX [Important Revision: a section is added constructing
the inner product/Hilbert space for the Witten-Carlip holonomy formulation;
the proof of unitary equivalence of the metric and holonomy formulations is
then completed. Other additions include discussion of relation of canonical
and unitary transformations. Title/abstract change.]
| null |
10.1103/PhysRevD.47.4458
|
Imperial/TP/92-93/02
|
gr-qc hep-th
| null |
Recent work on canonical transformations in quantum mechanics is applied to
transform between the Moncrief metric formulation and the Witten-Carlip
holonomy formulation of 2+1-dimensional quantum gravity on the torus. A
non-polynomial factor ordering of the classical canonical transformation
between the metric and holonomy variables is constructed which preserves their
classical modular transformation properties. An extension of the definition of
a unitary transformation is briefly discussed and is used to find the inner
product in the holonomy variables which makes the canonical transformation
unitary. This defines the Hilbert space in the Witten-Carlip formulation which
is unitarily equivalent to the natural Hilbert space in the Moncrief
formulation. In addition, gravitational theta-states arising from ``large''
diffeomorphisms are found in the theory.
|
[
{
"created": "Tue, 13 Oct 1992 08:01:41 GMT",
"version": "v1"
},
{
"created": "Thu, 31 Dec 1992 16:53:09 GMT",
"version": "v2"
}
] |
2009-10-22
|
[
[
"Anderson",
"Arlen",
""
]
] |
Recent work on canonical transformations in quantum mechanics is applied to transform between the Moncrief metric formulation and the Witten-Carlip holonomy formulation of 2+1-dimensional quantum gravity on the torus. A non-polynomial factor ordering of the classical canonical transformation between the metric and holonomy variables is constructed which preserves their classical modular transformation properties. An extension of the definition of a unitary transformation is briefly discussed and is used to find the inner product in the holonomy variables which makes the canonical transformation unitary. This defines the Hilbert space in the Witten-Carlip formulation which is unitarily equivalent to the natural Hilbert space in the Moncrief formulation. In addition, gravitational theta-states arising from ``large'' diffeomorphisms are found in the theory.
|
1803.05443
|
Shahar Hod
|
Shahar Hod
|
Quasinormal modes and strong cosmic censorship in near-extremal
Kerr-Newman-de Sitter black-hole spacetimes
|
9 pages
|
Physics Letters B 780, 221 (2018)
|
10.1016/j.physletb.2018.03.020
| null |
gr-qc astro-ph.HE hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The quasinormal resonant modes of massless neutral fields in near-extremal
Kerr-Newman-de Sitter black-hole spacetimes are calculated in the eikonal
regime. It is explicitly proved that, in the angular momentum regime ${\bar a}>
\sqrt{{{1-2{\bar\Lambda}}\over{4+{\bar\Lambda}/3}}}$, the black-hole spacetimes
are characterized by slowly decaying resonant modes which are described by the
compact formula $\Im\omega(n)=\kappa_+\cdot(n+{1\over2})$ [here the physical
parameters $\{{\bar a},\kappa_+,{\bar\Lambda},n\}$ are respectively the
dimensionless angular momentum of the black hole, its characteristic surface
gravity, the dimensionless cosmological constant of the spacetime, and the
integer resonance parameter]. Our results support the validity of the Penrose
strong cosmic censorship conjecture in these black-hole spacetimes.
|
[
{
"created": "Wed, 14 Mar 2018 18:00:05 GMT",
"version": "v1"
}
] |
2018-04-04
|
[
[
"Hod",
"Shahar",
""
]
] |
The quasinormal resonant modes of massless neutral fields in near-extremal Kerr-Newman-de Sitter black-hole spacetimes are calculated in the eikonal regime. It is explicitly proved that, in the angular momentum regime ${\bar a}> \sqrt{{{1-2{\bar\Lambda}}\over{4+{\bar\Lambda}/3}}}$, the black-hole spacetimes are characterized by slowly decaying resonant modes which are described by the compact formula $\Im\omega(n)=\kappa_+\cdot(n+{1\over2})$ [here the physical parameters $\{{\bar a},\kappa_+,{\bar\Lambda},n\}$ are respectively the dimensionless angular momentum of the black hole, its characteristic surface gravity, the dimensionless cosmological constant of the spacetime, and the integer resonance parameter]. Our results support the validity of the Penrose strong cosmic censorship conjecture in these black-hole spacetimes.
|
2202.09010
|
Matt Visser
|
Joshua Baines, Thomas Berry, Alex Simpson, and Matt Visser (Victoria
University of Wellington)
|
Constant-$r$ geodesics in the Painleve-Gullstrand form of Lense-Thirring
spacetime
|
Note change in article title! V1: 24 pages, 0 figures. V2: added 1
reference; no physics changes; V3: now 26 pages; 4 figures; 2 more
references; terminology and presentation improved; some bug fixes, but
physics conclusions unchanged. This version accepted for publication in
General Relativity and Gravitation
| null |
10.1007/s10714-022-02963-y
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Herein we explore the non-equatorial constant-$r$ ("quasi-circular")
geodesics (both timelike and null) in the Painleve-Gullstrand variant of the
Lense-Thirring spacetime recently introduced by the current authors. Even
though the spacetime is not spherically symmetric, shells of constant-$r$
geodesics still exist. Whereas the radial motion is (by construction) utterly
trivial, determining the allowed locations of these constant-$r$ geodesics is
decidedly non-trivial, and the stability analysis is equally tricky. Regarding
the angular motion, these constant-$r$ orbits will be seen to exhibit both
precession and nutation -- typically with incommensurate frequencies. Thus this
constant-$r$ geodesic motion, though integrable in the precise technical sense,
is generically surface-filling, with the orbits completely covering a symmetric
equatorial band which is a segment of a spherical surface, (a so-called
"spherical zone"), and whose latitudinal extent is governed by delicate
interplay between the orbital angular momentum and the Carter constant. The
situation is qualitatively similar to that for the (exact) Kerr spacetime --
but we now see that any physical model having the same slow-rotation weak-field
limit as general relativity will still possess non-equatorial constant-$r$
geodesics.
|
[
{
"created": "Fri, 18 Feb 2022 03:41:47 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Mar 2022 03:55:31 GMT",
"version": "v2"
},
{
"created": "Tue, 19 Jul 2022 05:06:11 GMT",
"version": "v3"
}
] |
2022-08-17
|
[
[
"Baines",
"Joshua",
"",
"Victoria\n University of Wellington"
],
[
"Berry",
"Thomas",
"",
"Victoria\n University of Wellington"
],
[
"Simpson",
"Alex",
"",
"Victoria\n University of Wellington"
],
[
"Visser",
"Matt",
"",
"Victoria\n University of Wellington"
]
] |
Herein we explore the non-equatorial constant-$r$ ("quasi-circular") geodesics (both timelike and null) in the Painleve-Gullstrand variant of the Lense-Thirring spacetime recently introduced by the current authors. Even though the spacetime is not spherically symmetric, shells of constant-$r$ geodesics still exist. Whereas the radial motion is (by construction) utterly trivial, determining the allowed locations of these constant-$r$ geodesics is decidedly non-trivial, and the stability analysis is equally tricky. Regarding the angular motion, these constant-$r$ orbits will be seen to exhibit both precession and nutation -- typically with incommensurate frequencies. Thus this constant-$r$ geodesic motion, though integrable in the precise technical sense, is generically surface-filling, with the orbits completely covering a symmetric equatorial band which is a segment of a spherical surface, (a so-called "spherical zone"), and whose latitudinal extent is governed by delicate interplay between the orbital angular momentum and the Carter constant. The situation is qualitatively similar to that for the (exact) Kerr spacetime -- but we now see that any physical model having the same slow-rotation weak-field limit as general relativity will still possess non-equatorial constant-$r$ geodesics.
|
gr-qc/0302096
|
Abel Camacho
|
Abel Camacho (Dept. of Physics, Universidad Autonoma
Metropolitana-Iztapalapa)
|
Time Evolution of a Quantum Particle and a Generalized Uncertainty
Principle
|
Accepted in Gravitation, Relativity, Cosmology
|
Rel.Grav.Cosmol. 1 (2004) 89-95
| null | null |
gr-qc quant-ph
| null |
Some of the possible consequences of a generalized uncertainty principle
(which emerges in the context of string theory and quantum gravity models as a
consequence of fluctuations of the background metric) are analyzed considering
the case of a quantum particle immersed in a homogeneous gravitational field.
It will be shown that the expectation value of the momentum operator depends in
a novel way on the mass of the involved particle. This kind of physical
characteristics could be, in principle, detected. In other words, one way of
confronting against the experiment some of the models around quantum gravity is
given by the detection of the dependence upon the mass parameter of the
expectation value of the momentum operator.
|
[
{
"created": "Mon, 24 Feb 2003 17:32:25 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Camacho",
"Abel",
"",
"Dept. of Physics, Universidad Autonoma\n Metropolitana-Iztapalapa"
]
] |
Some of the possible consequences of a generalized uncertainty principle (which emerges in the context of string theory and quantum gravity models as a consequence of fluctuations of the background metric) are analyzed considering the case of a quantum particle immersed in a homogeneous gravitational field. It will be shown that the expectation value of the momentum operator depends in a novel way on the mass of the involved particle. This kind of physical characteristics could be, in principle, detected. In other words, one way of confronting against the experiment some of the models around quantum gravity is given by the detection of the dependence upon the mass parameter of the expectation value of the momentum operator.
|
1101.5235
|
Hongwei Yu
|
Hongwei Yu
|
Open quantum system approach to Gibbons-Hawking effect of de Sitter
space-time
|
8 pages, no figures, a few typos corrected, version published in PRL
|
Phys.Rev.Lett.106:061101,2011
|
10.1103/PhysRevLett.106.061101
| null |
gr-qc hep-th quant-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We analyze, in the paradigm of open quantum systems, the reduced dynamics of
a freely-falling two-level detector in de Sitter space-time in weak interaction
with a reservoir of fluctuating quantized conformal scalar fields in the de
Sitter invariant vacuum. We find that the detector is asymptotically driven to
a thermal state at the Gibbons-Hawking temperature, regardless of its initial
state. Our discussion therefore shows that the Gibbons-Hawking effect of de
Sitter space-time can be understood as a manifestation of thermalization
phenomena that involves decoherence and dissipation in open quantum systems.
|
[
{
"created": "Thu, 27 Jan 2011 09:46:13 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Feb 2011 01:06:14 GMT",
"version": "v2"
}
] |
2011-02-23
|
[
[
"Yu",
"Hongwei",
""
]
] |
We analyze, in the paradigm of open quantum systems, the reduced dynamics of a freely-falling two-level detector in de Sitter space-time in weak interaction with a reservoir of fluctuating quantized conformal scalar fields in the de Sitter invariant vacuum. We find that the detector is asymptotically driven to a thermal state at the Gibbons-Hawking temperature, regardless of its initial state. Our discussion therefore shows that the Gibbons-Hawking effect of de Sitter space-time can be understood as a manifestation of thermalization phenomena that involves decoherence and dissipation in open quantum systems.
|
0901.0904
|
Ettore Minguzzi
|
E. Minguzzi
|
On the global existence of time
|
11 pages, 3 figures. Third juried prize at the FQXi contest "The
nature of time". In this version some misprints have been fixed, and some
references have been updated
|
Int.J.Mod.Phys.D18:2135-2144,2009
|
10.1142/S021827180901617X
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The existence of a global time is often taken for granted but should instead
be considered as a matter of investigation. By using the tools of global
Lorentzian geometry I show that, under physically reasonable conditions, the
impossibility of finding a global time implies the singularity of spacetime.
|
[
{
"created": "Wed, 7 Jan 2009 20:37:39 GMT",
"version": "v1"
},
{
"created": "Tue, 22 Sep 2009 12:17:57 GMT",
"version": "v2"
}
] |
2010-02-17
|
[
[
"Minguzzi",
"E.",
""
]
] |
The existence of a global time is often taken for granted but should instead be considered as a matter of investigation. By using the tools of global Lorentzian geometry I show that, under physically reasonable conditions, the impossibility of finding a global time implies the singularity of spacetime.
|
1608.04262
|
Yu-Xiao Liu
|
Shao-Wen Wei, Bao-Min Gu, Yong-Qiang Wang, Yu-Xiao Liu
|
Photon emission of extremal Kerr-Newman black holes
|
v3: 7 pages, 1 figure, improved version
|
Eur. Phys. J. C 77 (2017) 128
|
10.1140/epjc/s10052-017-4699-7
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, we deal with the null geodesics extending from the
near-horizon region out to a distant observatory in an extremal Kerr-Newman
black hole background. In particular, using the matched asymptotic expansion
method, we analytically solve the null geodesics near the superradiant bound in
the form of algebraic equations. For the case that the photon trajectories are
limited in the equatorial plane, the shifts in the azimuthal angle and time are
obtained.
|
[
{
"created": "Mon, 15 Aug 2016 13:21:15 GMT",
"version": "v1"
},
{
"created": "Sat, 27 Aug 2016 10:29:24 GMT",
"version": "v2"
},
{
"created": "Sun, 29 Jan 2017 08:27:19 GMT",
"version": "v3"
}
] |
2017-03-02
|
[
[
"Wei",
"Shao-Wen",
""
],
[
"Gu",
"Bao-Min",
""
],
[
"Wang",
"Yong-Qiang",
""
],
[
"Liu",
"Yu-Xiao",
""
]
] |
In this paper, we deal with the null geodesics extending from the near-horizon region out to a distant observatory in an extremal Kerr-Newman black hole background. In particular, using the matched asymptotic expansion method, we analytically solve the null geodesics near the superradiant bound in the form of algebraic equations. For the case that the photon trajectories are limited in the equatorial plane, the shifts in the azimuthal angle and time are obtained.
|
2311.07612
|
Hamed Hadi
|
H. Hadi, Amin Rezaei Akbarieh
|
Dynamical non-locality in the near-horizon region of a black hole with
quantum time
| null | null | null | null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
The formalization of the modular energy operator within the curved spacetime
is achieved through the timeless approach proposed by Page and Wootters. The
investigation is motivated by the peculiar behavior of the near horizon region
of a black hole and its quantum effects, leading to a restriction of the study
to the immediate vicinity. The focus lies on the perspective of a static
observer positioned close to the horizon. This paper highlights the alteration
of the modular energy's behavior in this region compared to flat spacetime.
Furthermore, it is observed that the geometry of the spacetime influences the
non-local properties of the modular energy. Moreover, within the event horizon
of the black hole, the modular energy exhibits a completely distinct behavior,
rendering its modular behavior imperceptible in this specific region.
|
[
{
"created": "Sat, 11 Nov 2023 20:04:17 GMT",
"version": "v1"
}
] |
2023-11-15
|
[
[
"Hadi",
"H.",
""
],
[
"Akbarieh",
"Amin Rezaei",
""
]
] |
The formalization of the modular energy operator within the curved spacetime is achieved through the timeless approach proposed by Page and Wootters. The investigation is motivated by the peculiar behavior of the near horizon region of a black hole and its quantum effects, leading to a restriction of the study to the immediate vicinity. The focus lies on the perspective of a static observer positioned close to the horizon. This paper highlights the alteration of the modular energy's behavior in this region compared to flat spacetime. Furthermore, it is observed that the geometry of the spacetime influences the non-local properties of the modular energy. Moreover, within the event horizon of the black hole, the modular energy exhibits a completely distinct behavior, rendering its modular behavior imperceptible in this specific region.
|
1301.3686
|
Zacharias Roupas
|
Zacharias Roupas
|
Thermodynamical instabilities of perfect fluid spheres in General
Relativity
|
21 pages, 2 figures; section 5 added; one paragraph in conclusions
added
|
Class. Quantum Grav. 30 115018 (2013)
|
10.1088/0264-9381/30/11/115018
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
For a static, perfect fluid sphere with a general equation of state, we
obtain the relativistic equation of hydrostatic equilibrium, namely the
Tolman-Oppenheimer-Volkov equation, as the thermodynamical equilibrium in the
microcanonical, as well as the canonical, ensemble. We find that the stability
condition determined by the second variation of entropy coincides with the
dynamical stability condition derived by variations to first order in the
dynamical Einstein's equations. Thus, we show the equivalence of microcanonical
thermodynamical stability with linear dynamical stability for a static,
spherically symmetric field in General Relativity. We calculate the Newtonian
limit and find the interesting property, that the microcanonical ensemble in
General Relativity transforms to the canonical ensemble for non-relativistic
dust particles. Finally, for specific kinds of systems, we study the effect of
the cosmological constant to the microcanonical thermodynamical stability of
fluid spheres.
|
[
{
"created": "Wed, 16 Jan 2013 13:07:40 GMT",
"version": "v1"
},
{
"created": "Tue, 22 Jan 2013 11:11:33 GMT",
"version": "v2"
},
{
"created": "Mon, 13 May 2013 14:45:47 GMT",
"version": "v3"
}
] |
2013-05-14
|
[
[
"Roupas",
"Zacharias",
""
]
] |
For a static, perfect fluid sphere with a general equation of state, we obtain the relativistic equation of hydrostatic equilibrium, namely the Tolman-Oppenheimer-Volkov equation, as the thermodynamical equilibrium in the microcanonical, as well as the canonical, ensemble. We find that the stability condition determined by the second variation of entropy coincides with the dynamical stability condition derived by variations to first order in the dynamical Einstein's equations. Thus, we show the equivalence of microcanonical thermodynamical stability with linear dynamical stability for a static, spherically symmetric field in General Relativity. We calculate the Newtonian limit and find the interesting property, that the microcanonical ensemble in General Relativity transforms to the canonical ensemble for non-relativistic dust particles. Finally, for specific kinds of systems, we study the effect of the cosmological constant to the microcanonical thermodynamical stability of fluid spheres.
|
1705.03063
|
Ivan Booth
|
Ivan Booth, Hari K. Kunduri, Anna O'Grady
|
Unstable marginally outer trapped surfaces in static spherically
symmetric spacetimes
|
11 pages, 9 figures; V2: title changed to match published version
|
Phys. Rev. D 96, 024059 (2017)
|
10.1103/PhysRevD.96.024059
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We examine potential deformations of inner black hole and cosmological
horizons in Reissner-Nordstr\"om de-Sitter spacetimes. While the rigidity of
the outer black hole horizon is guaranteed by theorem, that theorem applies to
neither the inner black hole nor past cosmological horizon. Further for pure
deSitter spacetime it is clear that the cosmological horizon can be deformed
(by translation). For specific parameter choices, it is shown that both inner
black hole and cosmological horizons can be infinitesimally deformed. However
these do not extend to finite deformations. The corresponding results for
general spherically symmetric spacetimes are considered.
|
[
{
"created": "Mon, 8 May 2017 19:54:08 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Aug 2017 17:35:45 GMT",
"version": "v2"
}
] |
2017-08-16
|
[
[
"Booth",
"Ivan",
""
],
[
"Kunduri",
"Hari K.",
""
],
[
"O'Grady",
"Anna",
""
]
] |
We examine potential deformations of inner black hole and cosmological horizons in Reissner-Nordstr\"om de-Sitter spacetimes. While the rigidity of the outer black hole horizon is guaranteed by theorem, that theorem applies to neither the inner black hole nor past cosmological horizon. Further for pure deSitter spacetime it is clear that the cosmological horizon can be deformed (by translation). For specific parameter choices, it is shown that both inner black hole and cosmological horizons can be infinitesimally deformed. However these do not extend to finite deformations. The corresponding results for general spherically symmetric spacetimes are considered.
|
1305.6001
|
Liu Zhao
|
Liu Zhao, Wei Xu and Bin Zhu
|
Novel rotating hairy black hole in (2+1)-dimensions
|
15 pages. v2: New references and minor corrections
|
Commun. Theor. Phys. 61 (2014) 475-481
|
10.1088/0253-6102/61/4/12
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present some novel rotating hairy black hole metric in $(2+1)$ dimensions,
which is an exact solution to the field equations of the Einstein-scalar-AdS
theory with a non-minimal coupling. The scalar potential is determined by the
metric ansatz and consistency of the field equations and cannot be prescribed
arbitrarily. In the simplified, critical case, the scalar potential contains
two independent constant parameters, which are respectively related to the mass
and angular momentum of the black hole in a particular way. As long as the
angular momentum does not vanish, the metric can have zero, one or two
horizons. The case with no horizon is physically uninteresting because of the
curvature singularity lying at the origin. We identified the necessary
conditions for at least one horizon to be present in the solution, which
imposes some bound on the mass-angular momentum ratio. For some particular
choice of parameters our solution degenerates into some previously known black
hole solutions.
|
[
{
"created": "Sun, 26 May 2013 08:00:12 GMT",
"version": "v1"
},
{
"created": "Mon, 3 Jun 2013 02:17:21 GMT",
"version": "v2"
}
] |
2015-06-16
|
[
[
"Zhao",
"Liu",
""
],
[
"Xu",
"Wei",
""
],
[
"Zhu",
"Bin",
""
]
] |
We present some novel rotating hairy black hole metric in $(2+1)$ dimensions, which is an exact solution to the field equations of the Einstein-scalar-AdS theory with a non-minimal coupling. The scalar potential is determined by the metric ansatz and consistency of the field equations and cannot be prescribed arbitrarily. In the simplified, critical case, the scalar potential contains two independent constant parameters, which are respectively related to the mass and angular momentum of the black hole in a particular way. As long as the angular momentum does not vanish, the metric can have zero, one or two horizons. The case with no horizon is physically uninteresting because of the curvature singularity lying at the origin. We identified the necessary conditions for at least one horizon to be present in the solution, which imposes some bound on the mass-angular momentum ratio. For some particular choice of parameters our solution degenerates into some previously known black hole solutions.
|
2011.10354
|
Claudio Meringolo
|
Claudio Meringolo, Sergio Servidio and Pierluigi Veltri
|
A spectral method algorithm for numerical simulations of gravitational
fields
|
38 pages, 14 figures
| null |
10.1088/1361-6382/abdd0b
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A numerical study of the Einstein field equations, based on the 3+1 foliation
of the spacetime, is presented. A pseudo-spectral technique has been employed
for simulations in vacuum, within two different formalisms, namely the
Arnowitt-Deser-Misner (ADM) and the conformal
Baumgarte-Shapiro-Shibata-Nakamura (BSSN) approach. The numerical code is based
on the Fourier decomposition, accompanied by different filtering techniques.
The role of the dealiasing, as well as the influence of the filter type, has
been investigated. The algorithms have been stabilized via a novel procedure
that controls self-consistently the regularity of the solutions. The accuracy
of the model has been validated through standard testbeds, revealing that the
filtered pseudo-spectral technique is among the most accurate approaches.
Finally, the procedure has been stressed via black hole dynamics and a new
strategy, based on hyperviscous dissipation that suppresses spurious boundary
problems, has been proposed. The model represents a valid tool of
investigation, particularly suitable for the inspection of small scale
nonlinear phenomena in gravitational dynamics.
|
[
{
"created": "Fri, 20 Nov 2020 11:36:50 GMT",
"version": "v1"
}
] |
2021-06-09
|
[
[
"Meringolo",
"Claudio",
""
],
[
"Servidio",
"Sergio",
""
],
[
"Veltri",
"Pierluigi",
""
]
] |
A numerical study of the Einstein field equations, based on the 3+1 foliation of the spacetime, is presented. A pseudo-spectral technique has been employed for simulations in vacuum, within two different formalisms, namely the Arnowitt-Deser-Misner (ADM) and the conformal Baumgarte-Shapiro-Shibata-Nakamura (BSSN) approach. The numerical code is based on the Fourier decomposition, accompanied by different filtering techniques. The role of the dealiasing, as well as the influence of the filter type, has been investigated. The algorithms have been stabilized via a novel procedure that controls self-consistently the regularity of the solutions. The accuracy of the model has been validated through standard testbeds, revealing that the filtered pseudo-spectral technique is among the most accurate approaches. Finally, the procedure has been stressed via black hole dynamics and a new strategy, based on hyperviscous dissipation that suppresses spurious boundary problems, has been proposed. The model represents a valid tool of investigation, particularly suitable for the inspection of small scale nonlinear phenomena in gravitational dynamics.
|
2304.05426
|
Parampreet Singh
|
Bao-Fei Li, Parampreet Singh
|
Loop Quantum Cosmology: Physics of Singularity Resolution and its
Implications
|
48 pages, 3 figures. Invited chapter to appear in the "Handbook of
Quantum Gravity", edited by Cosimo Bambi, Leonardo Modesto and Ilya Shapiro,
Springer (2023)
| null | null | null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The occurrence of singularities where spacetime curvature becomes infinite
and geodesic evolution breaks down are inevitable events in classical general
relativity (GR) unless one chooses an exotic matter violating weak energy
condition. These singularities show up in various physical processes, such as
the gravitational collapse, the birth of the universe in the standard cosmology
as well as the classical solutions of the black hole spacetimes. In the last
two decades, a rigorous understanding of the dynamics of quantum spacetime and
the way it resolves singularities has been achieved in loop quantum cosmology
(LQC) which applies the concepts and techniques of loop quantum gravity to the
symmetry reduced cosmological spacetimes. Due to the fundamental discreteness
of quantum geometry derived from the quantum theory, the big bang singularity
has been robustly shown to be replaced by a big bounce. Strong curvature
singularities intrinsic in the classical cosmology are generically resolved for
a variety of cosmological spacetimes including anisotropic models and polarized
Gowdy models. Using effective spacetime description the LQC universe also
provides an ultra-violet complete description of the classical inflationary
scenario as well as its alternatives such as the ekpyrotic and matter bounce
scenarios. In this chapter we provide a summary of singularity resolution and
its physical implications for various isotropic and anisotropic cosmological
spacetimes in LQC and analyze robustness of results through variant models
originating from different quantization prescriptions.
|
[
{
"created": "Tue, 11 Apr 2023 18:01:05 GMT",
"version": "v1"
}
] |
2023-04-13
|
[
[
"Li",
"Bao-Fei",
""
],
[
"Singh",
"Parampreet",
""
]
] |
The occurrence of singularities where spacetime curvature becomes infinite and geodesic evolution breaks down are inevitable events in classical general relativity (GR) unless one chooses an exotic matter violating weak energy condition. These singularities show up in various physical processes, such as the gravitational collapse, the birth of the universe in the standard cosmology as well as the classical solutions of the black hole spacetimes. In the last two decades, a rigorous understanding of the dynamics of quantum spacetime and the way it resolves singularities has been achieved in loop quantum cosmology (LQC) which applies the concepts and techniques of loop quantum gravity to the symmetry reduced cosmological spacetimes. Due to the fundamental discreteness of quantum geometry derived from the quantum theory, the big bang singularity has been robustly shown to be replaced by a big bounce. Strong curvature singularities intrinsic in the classical cosmology are generically resolved for a variety of cosmological spacetimes including anisotropic models and polarized Gowdy models. Using effective spacetime description the LQC universe also provides an ultra-violet complete description of the classical inflationary scenario as well as its alternatives such as the ekpyrotic and matter bounce scenarios. In this chapter we provide a summary of singularity resolution and its physical implications for various isotropic and anisotropic cosmological spacetimes in LQC and analyze robustness of results through variant models originating from different quantization prescriptions.
|
2203.11122
|
Olivier Minazzoli
|
Olivier Minazzoli
|
Black-holes and neutron stars in entangled relativity
|
Contribution to the 2022 Gravitation session of the 56th Rencontres
de Moriond
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
I present two results that show that, despite its unusual non-linear form,
the phenomenology of entangled relativity remains close to the one of general
relativity -- without having any free parameter that can be fine tuned in order
to facilitate this. In particular, I present the analytical solutions for
spherically charged black-holes, and both the analytical and numerical
solutions for neutron stars.
|
[
{
"created": "Mon, 21 Mar 2022 16:48:50 GMT",
"version": "v1"
}
] |
2022-03-22
|
[
[
"Minazzoli",
"Olivier",
""
]
] |
I present two results that show that, despite its unusual non-linear form, the phenomenology of entangled relativity remains close to the one of general relativity -- without having any free parameter that can be fine tuned in order to facilitate this. In particular, I present the analytical solutions for spherically charged black-holes, and both the analytical and numerical solutions for neutron stars.
|
gr-qc/0702147
|
Farook Rahaman
|
F.Rahaman, M.Kalam, R.Mukherjee, S.Das and T.Roy
|
Vacuum less global monopole in Brans-Dicke theory
|
6 pages, submitted to Theo. Math. Comp. Phys
| null | null | null |
gr-qc
| null |
In the present work, the gravitational field of a vacuum less global monopole
has been investigated in Brans-Dicke theory under weak field assumption of the
field equations. It has been shown that the vacuum less global monopole exerts
attractive gravitational effects on a test particle. It is dissimilar to the
case studied in general relativity.
|
[
{
"created": "Wed, 28 Feb 2007 08:56:22 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Rahaman",
"F.",
""
],
[
"Kalam",
"M.",
""
],
[
"Mukherjee",
"R.",
""
],
[
"Das",
"S.",
""
],
[
"Roy",
"T.",
""
]
] |
In the present work, the gravitational field of a vacuum less global monopole has been investigated in Brans-Dicke theory under weak field assumption of the field equations. It has been shown that the vacuum less global monopole exerts attractive gravitational effects on a test particle. It is dissimilar to the case studied in general relativity.
|
1805.07650
|
Yuri Pavlov
|
Yu. V. Pavlov, O. B. Zaslavskii
|
Regular frames and particle's rotation near a black hole
|
11 pages, 1 figure. Misprints in eq. (27) corrected. Matches
published version
|
Gen. Relativ. Gravit. (2019) 51: 60
|
10.1007/s10714-019-2544-z
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We consider a particle moving towards a rotating black hole. We are
interested in the number of its revolution $n$ around a black hole. In our
previous work (Pavlov and Zaslavskii in Gen Relativ Gravit 50: 14, 2018.
arXiv:1707.02860) we considered this issue in the Boyer-Lindquist type of
coordinates with a subsequent procedure of subtraction. Now, we reconsider this
issue using from the very beginning the frames regular on the horizon. For a
nonextremal black hole, regularity of a coordinate frame leads to the
finiteness of a number of revolutions around a black hole without a subtraction
procedure. Meanwhile, for extremal black holes comparison of $n$ calculated in
the regular frame with some subtraction procedures used by us earlier shows
that the results can be different.
|
[
{
"created": "Sat, 19 May 2018 20:23:27 GMT",
"version": "v1"
},
{
"created": "Tue, 14 May 2019 18:32:04 GMT",
"version": "v2"
}
] |
2019-05-16
|
[
[
"Pavlov",
"Yu. V.",
""
],
[
"Zaslavskii",
"O. B.",
""
]
] |
We consider a particle moving towards a rotating black hole. We are interested in the number of its revolution $n$ around a black hole. In our previous work (Pavlov and Zaslavskii in Gen Relativ Gravit 50: 14, 2018. arXiv:1707.02860) we considered this issue in the Boyer-Lindquist type of coordinates with a subsequent procedure of subtraction. Now, we reconsider this issue using from the very beginning the frames regular on the horizon. For a nonextremal black hole, regularity of a coordinate frame leads to the finiteness of a number of revolutions around a black hole without a subtraction procedure. Meanwhile, for extremal black holes comparison of $n$ calculated in the regular frame with some subtraction procedures used by us earlier shows that the results can be different.
|
gr-qc/0205118
|
Edward Anderson
|
Edward Anderson
|
Strong-coupled Relativity without Relativity
|
To appear in Gen. Rel. Grav. 2 typos corrected and one reference
updated
|
Gen.Rel.Grav. 36 (2004) 255-276
|
10.1023/B:GERG.0000010474.63835.2c
| null |
gr-qc
| null |
GR can be interpreted as a theory of evolving 3-geometries. A recent such
formulation, the 3-space approach of Barbour, Foster and \'{O} Murchadha, also
permits the construction of a limited number of other theories of evolving
3-geometries, including conformal gravity and strong gravity. In this paper, we
use the 3-space approach to construct a 1-parameter family of theories which
generalize strong gravity. The usual strong gravity is the strong-coupled limit
of GR, which is appropriate near singularities and is one of very few regimes
of GR which is amenable to quantization. Our new strong gravity theories are
similar limits of scalar-tensor theories such as Brans--Dicke theory, and are
likewise appropriate near singularities. They represent an extension of the
regime amenable to quantization, which furthermore spans two qualitatively
different types of inner product.
We find that strong gravity theories permit coupling only to ultralocal
matter fields and that they prevent gauge theory. Thus in the classical
picture, gauge theory breaks down (rather than undergoing unification) as one
approaches the GR initial singularity.
|
[
{
"created": "Tue, 28 May 2002 17:25:37 GMT",
"version": "v1"
},
{
"created": "Fri, 4 Oct 2002 14:35:50 GMT",
"version": "v2"
},
{
"created": "Mon, 7 Apr 2003 16:31:07 GMT",
"version": "v3"
},
{
"created": "Mon, 3 Nov 2003 21:30:37 GMT",
"version": "v4"
}
] |
2009-11-07
|
[
[
"Anderson",
"Edward",
""
]
] |
GR can be interpreted as a theory of evolving 3-geometries. A recent such formulation, the 3-space approach of Barbour, Foster and \'{O} Murchadha, also permits the construction of a limited number of other theories of evolving 3-geometries, including conformal gravity and strong gravity. In this paper, we use the 3-space approach to construct a 1-parameter family of theories which generalize strong gravity. The usual strong gravity is the strong-coupled limit of GR, which is appropriate near singularities and is one of very few regimes of GR which is amenable to quantization. Our new strong gravity theories are similar limits of scalar-tensor theories such as Brans--Dicke theory, and are likewise appropriate near singularities. They represent an extension of the regime amenable to quantization, which furthermore spans two qualitatively different types of inner product. We find that strong gravity theories permit coupling only to ultralocal matter fields and that they prevent gauge theory. Thus in the classical picture, gauge theory breaks down (rather than undergoing unification) as one approaches the GR initial singularity.
|
2311.18421
|
Trevor Scheopner
|
Trevor Scheopner, Justin Vines
|
Dynamical Implications of the Kerr Multipole Moments for Spinning Black
Holes
|
v2: revised count of operators, corrected typos
| null | null | null |
gr-qc hep-th
|
http://creativecommons.org/licenses/by/4.0/
|
Previously the linearized stress tensor of a stationary Kerr black hole has
been used to determine some of the values of gravitational couplings for a
spinning black hole to linear order in the Riemann tensor in the action
(worldline or quantum field theory). In particular, the couplings on operators
containing derivative structures of the form $(S\cdot\nabla)^n$ acting on the
Riemann tensor were fixed, with $S^\mu$ the spin vector of the black hole. In
this paper we find that the Kerr solution determines all of the multipole
moments in the sense of Dixon of a stationary spinning black hole and that
these multipole moments determine all linear in $R$ couplings. For example,
additional couplings beyond the previously mentioned are fixed on operators
containing derivative structures of the form $S^{2n}(p\cdot\nabla)^{2n}$ acting
on the Riemann tensor with $p^\mu$ the momentum vector of the black hole. These
additional operators do not contribute to the three-point amplitude, and so do
no contribute to the linearized stress tensor for a stationary black hole.
However, we find that they do contribute to the Compton amplitude.
Additionally, we derive formal expressions for the electromagnetic and
gravitational Compton amplitudes of generic spinning bodies to all orders in
spin in the worldline formalism and evaluated expressions for these amplitudes
to order $S^3$ in electromagnetism and order $S^5$ in gravity.
|
[
{
"created": "Thu, 30 Nov 2023 10:16:30 GMT",
"version": "v1"
},
{
"created": "Wed, 13 Dec 2023 18:46:58 GMT",
"version": "v2"
}
] |
2023-12-14
|
[
[
"Scheopner",
"Trevor",
""
],
[
"Vines",
"Justin",
""
]
] |
Previously the linearized stress tensor of a stationary Kerr black hole has been used to determine some of the values of gravitational couplings for a spinning black hole to linear order in the Riemann tensor in the action (worldline or quantum field theory). In particular, the couplings on operators containing derivative structures of the form $(S\cdot\nabla)^n$ acting on the Riemann tensor were fixed, with $S^\mu$ the spin vector of the black hole. In this paper we find that the Kerr solution determines all of the multipole moments in the sense of Dixon of a stationary spinning black hole and that these multipole moments determine all linear in $R$ couplings. For example, additional couplings beyond the previously mentioned are fixed on operators containing derivative structures of the form $S^{2n}(p\cdot\nabla)^{2n}$ acting on the Riemann tensor with $p^\mu$ the momentum vector of the black hole. These additional operators do not contribute to the three-point amplitude, and so do no contribute to the linearized stress tensor for a stationary black hole. However, we find that they do contribute to the Compton amplitude. Additionally, we derive formal expressions for the electromagnetic and gravitational Compton amplitudes of generic spinning bodies to all orders in spin in the worldline formalism and evaluated expressions for these amplitudes to order $S^3$ in electromagnetism and order $S^5$ in gravity.
|
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