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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1504.02767
|
Jonathan R. Gair
|
Jonathan R. Gair, Christopher J. Moore
|
Quantifying and mitigating bias in inference on gravitational wave
source populations
|
11 pages, 1 figure, to appear in Phys. Rev. D; v2 includes minor
changes for consistency with accepted version
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
When using incorrect or inaccurate signal models to perform parameter
estimation on a gravitational wave signal, biased parameter estimates will in
general be obtained. For a single event this bias may be consistent with the
posterior, but when considering a population of events this bias becomes
evident as a sag below the expected diagonal line of the P-P plot showing the
fraction of signals found within a certain significance level versus that
significance level. It would be hoped that recently proposed techniques for
accounting for model uncertainties in parameter estimation would, to some
extent, alleviate this problem. Here we demonstrate that this is indeed the
case. We derive an analytic approximation to the P-P plot obtained when using
an incorrect signal model to perform parameter estimation. This approximation
is valid in the limit of high signal-to-noise ratio and nearly correct waveform
models. We show how the P-P plot changes if a Gaussian process likelihood that
allows for model errors is used to analyse the data. We demonstrate
analytically and using numerical simulations that the bias is always reduced in
this way. These results provide a way to quantify bias in inference on
populations and demonstrate the importance of utilising methods to mitigate
this bias.
|
[
{
"created": "Fri, 10 Apr 2015 19:32:52 GMT",
"version": "v1"
},
{
"created": "Fri, 29 May 2015 09:16:10 GMT",
"version": "v2"
}
] |
2015-06-01
|
[
[
"Gair",
"Jonathan R.",
""
],
[
"Moore",
"Christopher J.",
""
]
] |
When using incorrect or inaccurate signal models to perform parameter estimation on a gravitational wave signal, biased parameter estimates will in general be obtained. For a single event this bias may be consistent with the posterior, but when considering a population of events this bias becomes evident as a sag below the expected diagonal line of the P-P plot showing the fraction of signals found within a certain significance level versus that significance level. It would be hoped that recently proposed techniques for accounting for model uncertainties in parameter estimation would, to some extent, alleviate this problem. Here we demonstrate that this is indeed the case. We derive an analytic approximation to the P-P plot obtained when using an incorrect signal model to perform parameter estimation. This approximation is valid in the limit of high signal-to-noise ratio and nearly correct waveform models. We show how the P-P plot changes if a Gaussian process likelihood that allows for model errors is used to analyse the data. We demonstrate analytically and using numerical simulations that the bias is always reduced in this way. These results provide a way to quantify bias in inference on populations and demonstrate the importance of utilising methods to mitigate this bias.
|
2112.11431
|
Michael A. Fedderke
|
Michael A. Fedderke, Peter W. Graham, and Surjeet Rajendran
|
Asteroids for $\mu$Hz gravitational-wave detection
|
50 pages, 9 figures. Published version
|
Phys. Rev. D 105, 103018 (2022)
|
10.1103/PhysRevD.105.103018
| null |
gr-qc astro-ph.CO astro-ph.IM hep-ph physics.atom-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A major challenge for gravitational-wave (GW) detection in the $\mu$Hz band
is engineering a test mass (TM) with sufficiently low acceleration noise. We
propose a GW detection concept using asteroids located in the inner Solar
System as TMs. Our main purpose is to evaluate the acceleration noise of
asteroids in the $\mu$Hz band. We show that a wide variety of environmental
perturbations are small enough to enable an appropriate class of $\sim 10$
km-diameter asteroids to be employed as TMs. This would allow a sensitive GW
detector in the band $\text{(few)} \times 10^{-7} \text{Hz} \lesssim
f_{\text{GW}} \lesssim \text{(few)} \times 10^{-5} \text{Hz}$, reaching strain
$h_c \sim 10^{-19}$ around $f_{\text{GW}} \sim 10 \mu$Hz, sufficient to detect
a wide variety of sources. To exploit these asteroid TMs, human-engineered base
stations could be deployed on multiple asteroids, each equipped with an
electromagnetic transmitter/receiver to permit measurement of variations in the
distance between them. We discuss a potential conceptual design with two base
stations, each with a space-qualified optical atomic clock measuring the
round-trip electromagnetic pulse travel time via laser ranging. Tradespace
exists to optimize multiple aspects of this mission: for example, using a
radio-ranging or interferometric link system instead of laser ranging. This
motivates future dedicated technical design study. This mission concept holds
exceptional promise for accessing this GW frequency band.
|
[
{
"created": "Tue, 21 Dec 2021 18:48:52 GMT",
"version": "v1"
},
{
"created": "Wed, 18 May 2022 09:48:48 GMT",
"version": "v2"
}
] |
2022-05-19
|
[
[
"Fedderke",
"Michael A.",
""
],
[
"Graham",
"Peter W.",
""
],
[
"Rajendran",
"Surjeet",
""
]
] |
A major challenge for gravitational-wave (GW) detection in the $\mu$Hz band is engineering a test mass (TM) with sufficiently low acceleration noise. We propose a GW detection concept using asteroids located in the inner Solar System as TMs. Our main purpose is to evaluate the acceleration noise of asteroids in the $\mu$Hz band. We show that a wide variety of environmental perturbations are small enough to enable an appropriate class of $\sim 10$ km-diameter asteroids to be employed as TMs. This would allow a sensitive GW detector in the band $\text{(few)} \times 10^{-7} \text{Hz} \lesssim f_{\text{GW}} \lesssim \text{(few)} \times 10^{-5} \text{Hz}$, reaching strain $h_c \sim 10^{-19}$ around $f_{\text{GW}} \sim 10 \mu$Hz, sufficient to detect a wide variety of sources. To exploit these asteroid TMs, human-engineered base stations could be deployed on multiple asteroids, each equipped with an electromagnetic transmitter/receiver to permit measurement of variations in the distance between them. We discuss a potential conceptual design with two base stations, each with a space-qualified optical atomic clock measuring the round-trip electromagnetic pulse travel time via laser ranging. Tradespace exists to optimize multiple aspects of this mission: for example, using a radio-ranging or interferometric link system instead of laser ranging. This motivates future dedicated technical design study. This mission concept holds exceptional promise for accessing this GW frequency band.
|
1610.08791
|
Cosimo Bambi
|
M. Ghasemi-Nodehi, Cosimo Bambi
|
Constraining the Kerr parameters via X-ray reflection spectroscopy
|
8 pages, 5 figures. v2: refereed version
|
Phys. Rev. D 94, 104062 (2016)
|
10.1103/PhysRevD.94.104062
| null |
gr-qc astro-ph.HE
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In a recent paper [Ghasemi-Nodehi & Bambi, EPJC 76 (2016) 290], we have
proposed a new parametrization for testing the Kerr nature of astrophysical
black hole candidates. In the present work, we study the possibility of
constraining the "Kerr parameters" of our proposal using X-ray reflection
spectroscopy, the so-called iron line method. We simulate observations with the
LAD instrument on board of the future eXTP mission assuming an exposure time of
200~ks. We fit the simulated data to see if the Kerr parameters can be
constrained. If we have the correct astrophysical model, 200~ks observations
with LAD/eXTP can constrain all the Kerr parameters with the exception of
$b_{11}$, whose impact on the iron line profile is extremely weak and its
measurement looks very challenging.
|
[
{
"created": "Thu, 27 Oct 2016 14:13:49 GMT",
"version": "v1"
},
{
"created": "Tue, 29 Nov 2016 20:19:26 GMT",
"version": "v2"
}
] |
2016-11-30
|
[
[
"Ghasemi-Nodehi",
"M.",
""
],
[
"Bambi",
"Cosimo",
""
]
] |
In a recent paper [Ghasemi-Nodehi & Bambi, EPJC 76 (2016) 290], we have proposed a new parametrization for testing the Kerr nature of astrophysical black hole candidates. In the present work, we study the possibility of constraining the "Kerr parameters" of our proposal using X-ray reflection spectroscopy, the so-called iron line method. We simulate observations with the LAD instrument on board of the future eXTP mission assuming an exposure time of 200~ks. We fit the simulated data to see if the Kerr parameters can be constrained. If we have the correct astrophysical model, 200~ks observations with LAD/eXTP can constrain all the Kerr parameters with the exception of $b_{11}$, whose impact on the iron line profile is extremely weak and its measurement looks very challenging.
|
gr-qc/0309132
|
Michael T. Anderson
|
Michael T. Anderson
|
Asymptotic behavior of future-complete cosmological space-times
|
16pp, to appear in the Classical and Quantum Gravity issue in Honor
of Vince Moncrief. Updated, changes made to Prop. 4.5
|
Class.Quant.Grav. 21 (2004) S11-S28
| null | null |
gr-qc
| null |
This work discusses the apriori possible asymptotic behavior to the future,
for (vacuum) space-times which are geodesically complete to the future and
which admit a foliation by compact constant mean curvature Cauchy surfaces.
|
[
{
"created": "Sat, 27 Sep 2003 15:20:25 GMT",
"version": "v1"
},
{
"created": "Thu, 1 Jan 2004 15:24:23 GMT",
"version": "v2"
}
] |
2007-05-23
|
[
[
"Anderson",
"Michael T.",
""
]
] |
This work discusses the apriori possible asymptotic behavior to the future, for (vacuum) space-times which are geodesically complete to the future and which admit a foliation by compact constant mean curvature Cauchy surfaces.
|
2208.09028
|
Ernesto Contreras
|
E. Contreras, Z. Stuchlik
|
A simple protocol to construct solutions with vanishing complexity by
Gravitational Decoupling
|
A clarifying point not appearing in the published version regarding
the mimic constraint for the mass function, has been introduced in on page 5
|
Eur. Phys. J. C 82, 706 (2022)
|
10.1140/epjc/s10052-022-10684-4
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this work we develop a simple protocol to construct interior solutions
through Gravitational Decoupling by the Minimal Geometric Deformation extended
satisfying the vanishing complexity condition. The method is illustrated by
using Tolman VII and Tolman IV solutions as isotropic seeds.
|
[
{
"created": "Thu, 18 Aug 2022 19:01:51 GMT",
"version": "v1"
}
] |
2022-09-07
|
[
[
"Contreras",
"E.",
""
],
[
"Stuchlik",
"Z.",
""
]
] |
In this work we develop a simple protocol to construct interior solutions through Gravitational Decoupling by the Minimal Geometric Deformation extended satisfying the vanishing complexity condition. The method is illustrated by using Tolman VII and Tolman IV solutions as isotropic seeds.
|
gr-qc/9510070
|
Robert Mann
|
C. Alvarez and R.B. Mann
|
The Equivalence Principle and g-2 Experiments
|
4 pages, latex, epsf, 1 figure
|
Phys.Lett. B409 (1997) 83-87
|
10.1016/S0370-2693(97)00801-0
|
WATPHYS-TH95/06
|
gr-qc hep-ph
| null |
We consider the possibility of using measurements of anomalous magnetic
moments of elementary particles as a possible test of the Einstein Equivalence
Principle (EEP). For the class non-metric theories of gravity described by the
\tmu formalism we find several novel mechanisms for breaking the EEP, and
discuss the possibilities of setting new empirical constraints on such effects.
|
[
{
"created": "Tue, 31 Oct 1995 18:11:49 GMT",
"version": "v1"
}
] |
2009-10-28
|
[
[
"Alvarez",
"C.",
""
],
[
"Mann",
"R. B.",
""
]
] |
We consider the possibility of using measurements of anomalous magnetic moments of elementary particles as a possible test of the Einstein Equivalence Principle (EEP). For the class non-metric theories of gravity described by the \tmu formalism we find several novel mechanisms for breaking the EEP, and discuss the possibilities of setting new empirical constraints on such effects.
|
2211.07946
|
S. Shankaranarayanan
|
Swastik Bhattacharya (BITS-Hyderabad) and S. Shankaranarayanan (IIT
Bombay)
|
Effective field theory description of horizon-fluid determines the
scrambling time
|
Version to appear in Universe (Open Questions in Black Hole Physics)
|
Universe 8(11), 603 (2022)
|
10.3390/universe8110603
| null |
gr-qc hep-th physics.flu-dyn
|
http://creativecommons.org/licenses/by/4.0/
|
Black hole horizons interact with external fields when matter-energy falls
through them. Such non-stationary black hole horizons can be described using
viscous fluid equations. This work attempts to describe this process using
effective field theory methods. Such a description can provide important
insights beyond classical black hole physics. In this work, we construct a
low-energy effective field theory description for the horizon fluid of a
4-dimensional, asymptotically flat, Einstein black hole. The effective field
theory of the dynamical horizon has two ingredients: degrees of freedom
involved in the interaction with external fields and symmetry. The dual
requirements of incorporating near-horizon symmetries (${\cal S}1$
diffeomorphism) and possessing length scales due to external perturbations is
naturally satisfied if the theory on the non-stationary black hole horizon is a
deformed Conformal Field Theory (CFT). For the homogeneous external
perturbations, at the lowest order, this leads to $(2 + 1)-$dimensional massive
scalar field where the mass is related to the extent of the deformation of the
CFT. We determine the mass by obtaining the correlation function corresponding
to the effective field and relating it to the bulk viscosity of the horizon
fluid. Additionally, we show that the coefficient of bulk viscosity of the
horizon fluid determines the time required for black holes to scramble.
Furthermore, we argue that matter-field modes with energy less than $m_{\rm
eff}$ falling into the horizon thermalize more slowly. Finally, we construct a
microscopic toy model for the horizon fluid that reduces to the effective field
theory with a single scalar degree of freedom. We then discuss the usefulness
of the effective field model in understanding how information escapes from a
black hole at late times.
|
[
{
"created": "Tue, 15 Nov 2022 07:13:34 GMT",
"version": "v1"
}
] |
2022-11-18
|
[
[
"Bhattacharya",
"Swastik",
"",
"BITS-Hyderabad"
],
[
"Shankaranarayanan",
"S.",
"",
"IIT\n Bombay"
]
] |
Black hole horizons interact with external fields when matter-energy falls through them. Such non-stationary black hole horizons can be described using viscous fluid equations. This work attempts to describe this process using effective field theory methods. Such a description can provide important insights beyond classical black hole physics. In this work, we construct a low-energy effective field theory description for the horizon fluid of a 4-dimensional, asymptotically flat, Einstein black hole. The effective field theory of the dynamical horizon has two ingredients: degrees of freedom involved in the interaction with external fields and symmetry. The dual requirements of incorporating near-horizon symmetries (${\cal S}1$ diffeomorphism) and possessing length scales due to external perturbations is naturally satisfied if the theory on the non-stationary black hole horizon is a deformed Conformal Field Theory (CFT). For the homogeneous external perturbations, at the lowest order, this leads to $(2 + 1)-$dimensional massive scalar field where the mass is related to the extent of the deformation of the CFT. We determine the mass by obtaining the correlation function corresponding to the effective field and relating it to the bulk viscosity of the horizon fluid. Additionally, we show that the coefficient of bulk viscosity of the horizon fluid determines the time required for black holes to scramble. Furthermore, we argue that matter-field modes with energy less than $m_{\rm eff}$ falling into the horizon thermalize more slowly. Finally, we construct a microscopic toy model for the horizon fluid that reduces to the effective field theory with a single scalar degree of freedom. We then discuss the usefulness of the effective field model in understanding how information escapes from a black hole at late times.
|
2406.03568
|
Elise S\"anger
|
Elise M. S\"anger, Soumen Roy, Michalis Agathos, Ofek Birnholtz,
Alessandra Buonanno, Tim Dietrich, Maria Haney, F\'elix-Louis Juli\'e,
Geraint Pratten, Jan Steinhoff, Chris Van Den Broeck, Sylvia Biscoveanu,
Prasanta Char, Anna Heffernan, Prathamesh Joshi, Atul Kedia, R. M. S.
Schofield, M. Trevor, and Michael Zevin
|
Tests of General Relativity with GW230529: a neutron star merging with a
lower mass-gap compact object
|
19 pages, 9 figures
| null | null |
LIGO-P2400200
|
gr-qc astro-ph.HE
|
http://creativecommons.org/licenses/by/4.0/
|
On 29 May 2023, the LIGO Livingston observatory detected the
gravitational-wave signal GW230529_181500 from the merger of a neutron star
with a lower mass-gap compact object. Its long inspiral signal provides a
unique opportunity to test General Relativity (GR) in a parameter space
previously unexplored by strong-field tests. In this work, we performed
parameterized inspiral tests of GR with GW230529_181500. Specifically, we
search for deviations in the frequency-domain GW phase by allowing for agnostic
corrections to the post-Newtonian coefficients. We performed tests with the
Flexible Theory Independent (FTI) and Test Infrastructure for General
Relativity (TIGER) frameworks using several quasi-circular waveform models that
capture different physical effects (higher modes, spins, tides). We find that
the signal is consistent with GR for all deviation parameters. Assuming the
primary object is a black hole, we obtain particularly tight constraints on the
dipole radiation at $-1$PN order of $|\delta\hat{\varphi}_{-2}| \lesssim 8
\times 10^{-5}$, which is a factor $\sim17$ times more stringent than previous
bounds from the neutron star--black hole merger GW200115_042309, as well as on
the 0.5PN and 1PN deviation parameters. We discuss some challenges that arise
when analyzing this signal, namely biases due to correlations with tidal
effects and the degeneracy between the 0PN deviation parameter and the chirp
mass. To illustrate the importance of GW230529_181500 for tests of GR, we
mapped the agnostic $-1$PN results to a class of Einstein-scalar-Gauss-Bonnet
(ESGB) theories of gravity. We also conducted an analysis probing the specific
phase deviation expected in ESGB theory and obtain an upper bound on the
Gauss-Bonnet coupling of $\ell_{\rm GB} \lesssim 0.51~\rm{M}_\odot$
($\sqrt{\alpha_{\rm GB}} \lesssim 0.28$ km), which is better than any
previously reported constraint.
|
[
{
"created": "Wed, 5 Jun 2024 18:30:33 GMT",
"version": "v1"
}
] |
2024-06-07
|
[
[
"Sänger",
"Elise M.",
""
],
[
"Roy",
"Soumen",
""
],
[
"Agathos",
"Michalis",
""
],
[
"Birnholtz",
"Ofek",
""
],
[
"Buonanno",
"Alessandra",
""
],
[
"Dietrich",
"Tim",
""
],
[
"Haney",
"Maria",
""
],
[
"Julié",
"Félix-Louis",
""
],
[
"Pratten",
"Geraint",
""
],
[
"Steinhoff",
"Jan",
""
],
[
"Broeck",
"Chris Van Den",
""
],
[
"Biscoveanu",
"Sylvia",
""
],
[
"Char",
"Prasanta",
""
],
[
"Heffernan",
"Anna",
""
],
[
"Joshi",
"Prathamesh",
""
],
[
"Kedia",
"Atul",
""
],
[
"Schofield",
"R. M. S.",
""
],
[
"Trevor",
"M.",
""
],
[
"Zevin",
"Michael",
""
]
] |
On 29 May 2023, the LIGO Livingston observatory detected the gravitational-wave signal GW230529_181500 from the merger of a neutron star with a lower mass-gap compact object. Its long inspiral signal provides a unique opportunity to test General Relativity (GR) in a parameter space previously unexplored by strong-field tests. In this work, we performed parameterized inspiral tests of GR with GW230529_181500. Specifically, we search for deviations in the frequency-domain GW phase by allowing for agnostic corrections to the post-Newtonian coefficients. We performed tests with the Flexible Theory Independent (FTI) and Test Infrastructure for General Relativity (TIGER) frameworks using several quasi-circular waveform models that capture different physical effects (higher modes, spins, tides). We find that the signal is consistent with GR for all deviation parameters. Assuming the primary object is a black hole, we obtain particularly tight constraints on the dipole radiation at $-1$PN order of $|\delta\hat{\varphi}_{-2}| \lesssim 8 \times 10^{-5}$, which is a factor $\sim17$ times more stringent than previous bounds from the neutron star--black hole merger GW200115_042309, as well as on the 0.5PN and 1PN deviation parameters. We discuss some challenges that arise when analyzing this signal, namely biases due to correlations with tidal effects and the degeneracy between the 0PN deviation parameter and the chirp mass. To illustrate the importance of GW230529_181500 for tests of GR, we mapped the agnostic $-1$PN results to a class of Einstein-scalar-Gauss-Bonnet (ESGB) theories of gravity. We also conducted an analysis probing the specific phase deviation expected in ESGB theory and obtain an upper bound on the Gauss-Bonnet coupling of $\ell_{\rm GB} \lesssim 0.51~\rm{M}_\odot$ ($\sqrt{\alpha_{\rm GB}} \lesssim 0.28$ km), which is better than any previously reported constraint.
|
1412.6270
|
Xavier Calmet
|
Xavier Calmet
|
Virtual Black Holes, Remnants and the Information Paradox
|
8 pages
|
Class. Quantum Grav. 32 (2015) 045007
|
10.1088/0264-9381/32/4/045007
| null |
gr-qc hep-ph hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We revisit the question of the contributions of Planckian quantum black holes
in general and of remnants in particular to low energy physics observables. As
long as quantum gravity preserves the symmetries of the low energy effective
field theory, we find that the bounds on the number of quantum black holes or
remnants are very weak. Typically we rule out using data on the anomalous
magnetic moment of the muon that there are more than $10^{32}$ quantum black
holes coupled to the standard model particles gravitationally. Remnants thus
remain a viable option as a solution to the information paradox of black holes.
|
[
{
"created": "Fri, 19 Dec 2014 10:10:31 GMT",
"version": "v1"
}
] |
2015-06-23
|
[
[
"Calmet",
"Xavier",
""
]
] |
We revisit the question of the contributions of Planckian quantum black holes in general and of remnants in particular to low energy physics observables. As long as quantum gravity preserves the symmetries of the low energy effective field theory, we find that the bounds on the number of quantum black holes or remnants are very weak. Typically we rule out using data on the anomalous magnetic moment of the muon that there are more than $10^{32}$ quantum black holes coupled to the standard model particles gravitationally. Remnants thus remain a viable option as a solution to the information paradox of black holes.
|
0806.3504
|
Farook Rahaman
|
F. Rahaman and P. Ghosh
|
Gravitational field of domain wall in Lyra geometry
|
11 pages, 6 figures; Submitted in Astrophysics and Space Science
after minor revision
|
Astrophys.SpaceSci.317:127-132,2008
|
10.1007/s10509-008-9866-8
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, we study the domain wall with time dependent displacement
vectors based on Lyra geometry in normal gauge i.e. displacement vector $f^*_i
= [ \beta (t), 0,0,0]$. The field theoretic energy momentum tensor is
considered with zero pressure perpendicular to the wall. We find an exact
solutions of Einstein equation for a scalar field $\phi$ with a potential
$V(\phi)$ describing the gravitational field of a plane symmetric domain wall.
We have seen that the hyper surfaces parallel to the wall ($ z = constant $)
are three dimensional de-sitter spaces. It is also shown that the gravitational
field experienced by test particle is attractive.
|
[
{
"created": "Sat, 21 Jun 2008 09:29:37 GMT",
"version": "v1"
}
] |
2008-11-26
|
[
[
"Rahaman",
"F.",
""
],
[
"Ghosh",
"P.",
""
]
] |
In this paper, we study the domain wall with time dependent displacement vectors based on Lyra geometry in normal gauge i.e. displacement vector $f^*_i = [ \beta (t), 0,0,0]$. The field theoretic energy momentum tensor is considered with zero pressure perpendicular to the wall. We find an exact solutions of Einstein equation for a scalar field $\phi$ with a potential $V(\phi)$ describing the gravitational field of a plane symmetric domain wall. We have seen that the hyper surfaces parallel to the wall ($ z = constant $) are three dimensional de-sitter spaces. It is also shown that the gravitational field experienced by test particle is attractive.
|
2407.05646
|
Koray D\"uzta\c{s}
|
Koray D\"uzta\c{s}
|
Can the induced increase in the angular velocity prevent the
overspinning of BTZ black holes?
|
Accepted to appear in European Physical Journal C
|
Eur. Phys. J. C (2024) 84:669
|
10.1140/epjc/s10052-024-13062-4
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Previously we showed that nearly extremal Ba\~{n}ados-Teitelboim-Zanelli
(BTZ) black holes can be overspun by test bodies and fields, following the work
of Rocha and Cardoso for the extremal case. The naked singularities in AdS
space-times correspond to states rotating faster than light in the Ads/CFT
correspondence. Therefore, overspinning turns out to be a drastic problem in a
(2+1) dimensional AdS space-time, where one cannot invoke backreaction effects.
Here, we consider the induced increase in the angular velocity of the event
horizon which modifies the condition to allow the absorption of the
perturbations satisfying the null energy condition. We show that its magnitude
is sufficiently large to prevent the absorption of the challenging modes both
for test bodies and scalar fields. We bring a solution to the notorious
overspinning problem which does not involve any reference to self-energy or
gravitational radiation.
|
[
{
"created": "Mon, 8 Jul 2024 06:16:18 GMT",
"version": "v1"
}
] |
2024-07-09
|
[
[
"Düztaş",
"Koray",
""
]
] |
Previously we showed that nearly extremal Ba\~{n}ados-Teitelboim-Zanelli (BTZ) black holes can be overspun by test bodies and fields, following the work of Rocha and Cardoso for the extremal case. The naked singularities in AdS space-times correspond to states rotating faster than light in the Ads/CFT correspondence. Therefore, overspinning turns out to be a drastic problem in a (2+1) dimensional AdS space-time, where one cannot invoke backreaction effects. Here, we consider the induced increase in the angular velocity of the event horizon which modifies the condition to allow the absorption of the perturbations satisfying the null energy condition. We show that its magnitude is sufficiently large to prevent the absorption of the challenging modes both for test bodies and scalar fields. We bring a solution to the notorious overspinning problem which does not involve any reference to self-energy or gravitational radiation.
|
0911.1636
|
Brian Dolan
|
Brian P. Dolan
|
Chiral fermions and torsion in the early Universe
|
5 pages revtex4; error in v1 corrected.
|
Class.Quant.Grav.27:095010,2010; Erratum-ibid.27:249801,2010
|
10.1088/0264-9381/27/9/095010 10.1088/0264-9381/27/24/249801
|
DIAS-STP-10-01
|
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Torsion arising from fermionic matter in the Einstein-Cartan formulation of
general relativity is considered in the context of Robertson-Walker geometries
and the early Universe. An ambiguity in the way torsion arising from hot
fermionic matter in chiral models should be implemented is highlighted and
discussed. In one interpretation, chemical potentials in chiral models can
contribute to the Friedmann equation and give a negative contribution to the
energy density.
|
[
{
"created": "Mon, 9 Nov 2009 11:15:33 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Dec 2009 09:26:21 GMT",
"version": "v2"
},
{
"created": "Fri, 23 Apr 2010 08:18:21 GMT",
"version": "v3"
}
] |
2010-12-06
|
[
[
"Dolan",
"Brian P.",
""
]
] |
Torsion arising from fermionic matter in the Einstein-Cartan formulation of general relativity is considered in the context of Robertson-Walker geometries and the early Universe. An ambiguity in the way torsion arising from hot fermionic matter in chiral models should be implemented is highlighted and discussed. In one interpretation, chemical potentials in chiral models can contribute to the Friedmann equation and give a negative contribution to the energy density.
|
0912.0834
|
Jo\~ao Lopes Costa
|
Jo\~ao Lopes Costa
|
On the classification of stationary electro-vacuum black holes
| null |
Class.Quant.Grav. 27 (2010) 035010
|
10.1088/0264-9381/27/3/035010
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We obtain a classification of stationary, $I^+$--regular, non-degenerate and
analytic electro-vacuum space-times in terms of Weinstein solutions. In
particular, for connected horizons, we prove uniqueness of the Kerr-Newman
black holes.
|
[
{
"created": "Fri, 4 Dec 2009 12:23:03 GMT",
"version": "v1"
}
] |
2012-06-21
|
[
[
"Costa",
"João Lopes",
""
]
] |
We obtain a classification of stationary, $I^+$--regular, non-degenerate and analytic electro-vacuum space-times in terms of Weinstein solutions. In particular, for connected horizons, we prove uniqueness of the Kerr-Newman black holes.
|
1603.02554
|
Luca Fabbri
|
Luca Fabbri
|
A generally-relativistic gauge classification of the Dirac fields
|
7 pages
|
Int.J.Geom.Meth.Mod.Phys.:13,1650078(2016)
|
10.1142/S021988781650078X
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We consider generally-relativistic gauge transformations for the spinorial
fields finding two mutually exclusive but together exhaustive classes in which
fermions are placed adding supplementary information to the results obtained by
Lounesto, and identifying quantities analogous to the momentum vector and the
Pauli-Lubanski axial vector we discuss how our results are similar to those
obtained by Wigner; by taking into account the system of Dirac field equations
we will investigate the consequences for the dynamics: and in particular we
shall address the problem of getting the non-relativistic approximation in a
consistent way. We are going to comment on extensions.
|
[
{
"created": "Tue, 8 Mar 2016 15:36:35 GMT",
"version": "v1"
},
{
"created": "Tue, 19 Apr 2016 13:04:59 GMT",
"version": "v2"
},
{
"created": "Sat, 14 Jan 2017 01:33:49 GMT",
"version": "v3"
},
{
"created": "Mon, 22 May 2017 15:21:20 GMT",
"version": "v4"
}
] |
2017-05-23
|
[
[
"Fabbri",
"Luca",
""
]
] |
We consider generally-relativistic gauge transformations for the spinorial fields finding two mutually exclusive but together exhaustive classes in which fermions are placed adding supplementary information to the results obtained by Lounesto, and identifying quantities analogous to the momentum vector and the Pauli-Lubanski axial vector we discuss how our results are similar to those obtained by Wigner; by taking into account the system of Dirac field equations we will investigate the consequences for the dynamics: and in particular we shall address the problem of getting the non-relativistic approximation in a consistent way. We are going to comment on extensions.
|
2312.07127
|
Yong Xiao
|
Yong Xiao and Yue-Ying Liu
|
First order corrections to black hole thermodynamics: a simple approach
enhanced
|
6 pages, no figures
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Perturbation theory plays an essential role in the realm of physics,
especially when it is difficult or impossible to obtain exact solutions.
Incorporating higher derivative terms into the gravitational action leads to an
important perturbation problem. In this paper, we demonstrate that the first
order corrections to black hole thermodynamics, caused by any higher derivative
terms, can be achieved without explicitly solving the modified metric. This
enhances a simple approach discovered two decades ago and resolves the
controversy surrounding it. Astonishingly, we observe that the perturbation
theory of quantum mechanics also exhibits a similar behavior, which reveals the
existence of a universal theoretical structure underlying the perturbation
theories of black hole thermodynamics, quantum mechanics and even other
disciplines.
|
[
{
"created": "Tue, 12 Dec 2023 10:00:08 GMT",
"version": "v1"
},
{
"created": "Fri, 16 Feb 2024 10:00:51 GMT",
"version": "v2"
}
] |
2024-02-19
|
[
[
"Xiao",
"Yong",
""
],
[
"Liu",
"Yue-Ying",
""
]
] |
Perturbation theory plays an essential role in the realm of physics, especially when it is difficult or impossible to obtain exact solutions. Incorporating higher derivative terms into the gravitational action leads to an important perturbation problem. In this paper, we demonstrate that the first order corrections to black hole thermodynamics, caused by any higher derivative terms, can be achieved without explicitly solving the modified metric. This enhances a simple approach discovered two decades ago and resolves the controversy surrounding it. Astonishingly, we observe that the perturbation theory of quantum mechanics also exhibits a similar behavior, which reveals the existence of a universal theoretical structure underlying the perturbation theories of black hole thermodynamics, quantum mechanics and even other disciplines.
|
1005.3306
|
Lucia Santamaria
|
L. Santamaria, F. Ohme, P. Ajith, B. Bruegmann, N. Dorband, M. Hannam,
S. Husa, P. Moesta, D. Pollney, C. Reisswig, E. L. Robinson, J. Seiler and B.
Krishnan
|
Matching post-Newtonian and numerical relativity waveforms: systematic
errors and a new phenomenological model for non-precessing black hole
binaries
|
22 pages, 11 figures
|
Phys.Rev.D82:064016,2010
|
10.1103/PhysRevD.82.064016
|
LIGO-P1000048, AEI-2010-122
|
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present a new phenomenological gravitational waveform model for the
inspiral and coalescence of non-precessing spinning black hole binaries. Our
approach is based on a frequency domain matching of post-Newtonian inspiral
waveforms with numerical relativity based binary black hole coalescence
waveforms. We quantify the various possible sources of systematic errors that
arise in matching post-Newtonian and numerical relativity waveforms, and we use
a matching criteria based on minimizing these errors; we find that the dominant
source of errors are those in the post-Newtonian waveforms near the merger. An
analytical formula for the dominant mode of the gravitational radiation of
non-precessing black hole binaries is presented that captures the phenomenology
of the hybrid waveforms. Its implementation in the current searches for
gravitational waves should allow cross-checks of other inspiral-merger-ringdown
waveform families and improve the reach of gravitational wave searches.
|
[
{
"created": "Tue, 18 May 2010 20:00:07 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Jun 2010 12:11:03 GMT",
"version": "v2"
},
{
"created": "Tue, 3 Aug 2010 11:41:08 GMT",
"version": "v3"
}
] |
2015-03-17
|
[
[
"Santamaria",
"L.",
""
],
[
"Ohme",
"F.",
""
],
[
"Ajith",
"P.",
""
],
[
"Bruegmann",
"B.",
""
],
[
"Dorband",
"N.",
""
],
[
"Hannam",
"M.",
""
],
[
"Husa",
"S.",
""
],
[
"Moesta",
"P.",
""
],
[
"Pollney",
"D.",
""
],
[
"Reisswig",
"C.",
""
],
[
"Robinson",
"E. L.",
""
],
[
"Seiler",
"J.",
""
],
[
"Krishnan",
"B.",
""
]
] |
We present a new phenomenological gravitational waveform model for the inspiral and coalescence of non-precessing spinning black hole binaries. Our approach is based on a frequency domain matching of post-Newtonian inspiral waveforms with numerical relativity based binary black hole coalescence waveforms. We quantify the various possible sources of systematic errors that arise in matching post-Newtonian and numerical relativity waveforms, and we use a matching criteria based on minimizing these errors; we find that the dominant source of errors are those in the post-Newtonian waveforms near the merger. An analytical formula for the dominant mode of the gravitational radiation of non-precessing black hole binaries is presented that captures the phenomenology of the hybrid waveforms. Its implementation in the current searches for gravitational waves should allow cross-checks of other inspiral-merger-ringdown waveform families and improve the reach of gravitational wave searches.
|
1501.03524
|
Hideki Maeda
|
Hideki Maeda
|
The Roberts-(A)dS spacetime
|
8 pages, 7 figures, 1 table; v2, revised version, higher-dimensional
solution with k=0 given in appendix; v3, final version to appear in Classical
and Quantum Gravity
|
Class. Quant. Grav. 32, 135025 (2015)
|
10.1088/0264-9381/32/13/135025
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Global structure of the (anti-)de~Sitter ((A)dS) generalization of the
Roberts solution in general relativity with a massless scalar field and its
topological generalization is clarified. In the case with a negative
cosmological constant, the spacetime is asymptotically locally AdS and it
contains a black-hole event horizon depending on the parameters. The spacetime
may be attached to the exact AdS spacetime in a regular manner on a null
hypersurface and the resulting spacetime represents gravitational collapse from
a regular initial datum. The higher-dimensional counterpart of this
Roberts-(A)dS solution with flat base manifold is also given.
|
[
{
"created": "Wed, 14 Jan 2015 21:51:10 GMT",
"version": "v1"
},
{
"created": "Wed, 21 Jan 2015 08:37:57 GMT",
"version": "v2"
},
{
"created": "Mon, 1 Jun 2015 08:47:42 GMT",
"version": "v3"
}
] |
2021-11-02
|
[
[
"Maeda",
"Hideki",
""
]
] |
Global structure of the (anti-)de~Sitter ((A)dS) generalization of the Roberts solution in general relativity with a massless scalar field and its topological generalization is clarified. In the case with a negative cosmological constant, the spacetime is asymptotically locally AdS and it contains a black-hole event horizon depending on the parameters. The spacetime may be attached to the exact AdS spacetime in a regular manner on a null hypersurface and the resulting spacetime represents gravitational collapse from a regular initial datum. The higher-dimensional counterpart of this Roberts-(A)dS solution with flat base manifold is also given.
|
1307.3291
|
Valeri Frolov P
|
Valeri P. Frolov
|
Generalized Fermat's principle and action for light rays in a curved
spacetime
|
7 pages 1 figure
| null |
10.1103/PhysRevD.88.064039
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We start with formulation of the generalized Fermat's principle for light
propagation in a curved spacetime. We apply Pontryagin's minimum principle of
the optimal control theory and obtain an effective Hamiltonian for null
geodesics in a curved spacetime. We explicitly demonstrate that dynamical
equations for this Hamiltonian correctly reproduce null geodesic equations.
Other forms of the action for light rays in a curved spacetime are also
discussed.
|
[
{
"created": "Thu, 11 Jul 2013 23:05:28 GMT",
"version": "v1"
}
] |
2015-06-16
|
[
[
"Frolov",
"Valeri P.",
""
]
] |
We start with formulation of the generalized Fermat's principle for light propagation in a curved spacetime. We apply Pontryagin's minimum principle of the optimal control theory and obtain an effective Hamiltonian for null geodesics in a curved spacetime. We explicitly demonstrate that dynamical equations for this Hamiltonian correctly reproduce null geodesic equations. Other forms of the action for light rays in a curved spacetime are also discussed.
|
2001.01806
|
Albert Huber
|
Albert Huber
|
Distributional Metrics and the Action Principle of Einstein-Hilbert
Gravity
|
22 Pages, no figures
|
Class. Quantum Grav. 2020
|
10.1088/1361-6382/ab7614
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this work, a subclass of the generalized Kerr-Schild class of spacetimes
is specified, with respect to which the Ricci tensor (regardless of the
position of indices) proves to be linear in the so-called profile function of
the geometry. Considering Colombeau's nonlinear theory of generalized
functions, this result is extended to apply to an associated class of
distributional Kerr-Schild geometries, and then used to formulate a variational
principle for these singular spacetimes. More specifically, it is shown in this
regard that a variation of a suitably regularized Einstein-Hilbert action can
be performed even if the metric of one of the corresponding generalized
Kerr-Schild representatives contains a generalized delta function that
converges in a suitable limit to a delta distribution.
|
[
{
"created": "Mon, 6 Jan 2020 22:49:36 GMT",
"version": "v1"
}
] |
2020-02-17
|
[
[
"Huber",
"Albert",
""
]
] |
In this work, a subclass of the generalized Kerr-Schild class of spacetimes is specified, with respect to which the Ricci tensor (regardless of the position of indices) proves to be linear in the so-called profile function of the geometry. Considering Colombeau's nonlinear theory of generalized functions, this result is extended to apply to an associated class of distributional Kerr-Schild geometries, and then used to formulate a variational principle for these singular spacetimes. More specifically, it is shown in this regard that a variation of a suitably regularized Einstein-Hilbert action can be performed even if the metric of one of the corresponding generalized Kerr-Schild representatives contains a generalized delta function that converges in a suitable limit to a delta distribution.
|
gr-qc/0406094
|
Burkhard Kleihaus
|
B. Kleihaus, J. Kunz and F. Navarro-Lerida
|
Rotating Black Holes with Monopole Hair
|
13 pages, 8 figures
|
Phys.Lett. B599 (2004) 294-300
|
10.1016/j.physletb.2004.08.046
| null |
gr-qc
| null |
We study rotating black holes in Einstein-Yang-Mills-Higgs theory. These
black holes emerge from static black holes with monopole hair when a finite
horizon angular velocity is imposed. At critical values of the horizon angular
velocity and the horizon radius, they bifurcate with embedded Kerr-Newman black
holes. The non-Abelian black holes possess an electric dipole moment, but no
electric charge is induced by the rotation. We deduce that gravitating regular
monopoles possess a gyroelectric ratio g_el=2.
|
[
{
"created": "Wed, 23 Jun 2004 16:03:05 GMT",
"version": "v1"
}
] |
2009-11-10
|
[
[
"Kleihaus",
"B.",
""
],
[
"Kunz",
"J.",
""
],
[
"Navarro-Lerida",
"F.",
""
]
] |
We study rotating black holes in Einstein-Yang-Mills-Higgs theory. These black holes emerge from static black holes with monopole hair when a finite horizon angular velocity is imposed. At critical values of the horizon angular velocity and the horizon radius, they bifurcate with embedded Kerr-Newman black holes. The non-Abelian black holes possess an electric dipole moment, but no electric charge is induced by the rotation. We deduce that gravitating regular monopoles possess a gyroelectric ratio g_el=2.
|
1306.6521
|
Vladimir Ivashchuk
|
V. D. Ivashchuk and V. N. Melnikov
|
Quantum billiards in multidimensional models with fields of forms
|
14 pages, LaTex, no figures, several typos are eliminated
|
Gravitation and Cosmology 19, No 3, 171-177 (2013)
|
10.1134/S0202289313030055
|
IGC-PFUR-13/07-01/10-02corr
|
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Bianchi type I cosmological model in (n+1)-dimensional gravity with several
forms is considered. When the electric non-composite brane ansatz is adopted,
the Wheeler-DeWitt (WDW) equation for the model, written in a conformally
covariant form, is analyzed. Under certain restrictions, asymptotic solutions
to the WDW equation near the singularity are found, which reduce the problem to
the so-called quantum billiard on the (n-1)-dimensional Lobachevsky space
H^{n-1}. Two examples of quantum billiards are considered: a 2-dimensional
quantum billiard for a 4D model with three 2-forms and a 9D quantum billiard
for an 11D model with 120 4-forms which mimics SM2-brane sector of D=11
supergravity. For certain solutions, vanishing of the wave function at the
singularity is proved.
|
[
{
"created": "Thu, 27 Jun 2013 14:44:17 GMT",
"version": "v1"
},
{
"created": "Sat, 13 Jul 2013 11:15:04 GMT",
"version": "v2"
},
{
"created": "Fri, 18 Oct 2013 21:51:50 GMT",
"version": "v3"
},
{
"created": "Wed, 10 Sep 2014 15:16:38 GMT",
"version": "v4"
}
] |
2015-06-16
|
[
[
"Ivashchuk",
"V. D.",
""
],
[
"Melnikov",
"V. N.",
""
]
] |
Bianchi type I cosmological model in (n+1)-dimensional gravity with several forms is considered. When the electric non-composite brane ansatz is adopted, the Wheeler-DeWitt (WDW) equation for the model, written in a conformally covariant form, is analyzed. Under certain restrictions, asymptotic solutions to the WDW equation near the singularity are found, which reduce the problem to the so-called quantum billiard on the (n-1)-dimensional Lobachevsky space H^{n-1}. Two examples of quantum billiards are considered: a 2-dimensional quantum billiard for a 4D model with three 2-forms and a 9D quantum billiard for an 11D model with 120 4-forms which mimics SM2-brane sector of D=11 supergravity. For certain solutions, vanishing of the wave function at the singularity is proved.
|
1505.07760
|
Francesco Becattini
|
F. Becattini, E. Grossi (University of Florence, Italy)
|
Quantum corrections to the stress-energy tensor in thermodynamic
equilibrium with acceleration
|
18 pages, 1 figure. Minor changes, to appear in PRD
|
Phys. Rev. D 92, 045037 (2015)
|
10.1103/PhysRevD.92.045037
| null |
gr-qc hep-th nucl-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We show that the stress-energy tensor has additional terms with respect to
the ideal form in states of global thermodynamic equilibrium in flat spacetime
with non-vanishing acceleration and vorticity. These corrections are of quantum
origin and their leading terms are second order in the gradients of the
thermodynamic fields. Their relevant coefficients can be expressed in terms of
correlators of the stress-energy tensor operator and the generators of the
Lorentz group. With respect to previous assessments, we find that there are
more second order coefficients and that all thermodynamic functions including
energy density receive acceleration and vorticity dependent corrections.
Notably, also the relation between \rho and p, that is the equation of state,
is affected by acceleration and vorticity. We have calculated the corrections
for a free real scalar field -- both massive and massless -- and we have found
that they increase, particularly for a massive field, at very high acceleration
and vorticity and very low temperature. Finally, these non-ideal terms depend
on the explicit form of the stress-energy operator, implying that different
stress-energy tensor of the scalar field -- canonical or improved -- are
thermodynamically inequivalent.
|
[
{
"created": "Thu, 28 May 2015 17:14:22 GMT",
"version": "v1"
},
{
"created": "Tue, 18 Aug 2015 12:05:38 GMT",
"version": "v2"
}
] |
2015-09-02
|
[
[
"Becattini",
"F.",
"",
"University of Florence, Italy"
],
[
"Grossi",
"E.",
"",
"University of Florence, Italy"
]
] |
We show that the stress-energy tensor has additional terms with respect to the ideal form in states of global thermodynamic equilibrium in flat spacetime with non-vanishing acceleration and vorticity. These corrections are of quantum origin and their leading terms are second order in the gradients of the thermodynamic fields. Their relevant coefficients can be expressed in terms of correlators of the stress-energy tensor operator and the generators of the Lorentz group. With respect to previous assessments, we find that there are more second order coefficients and that all thermodynamic functions including energy density receive acceleration and vorticity dependent corrections. Notably, also the relation between \rho and p, that is the equation of state, is affected by acceleration and vorticity. We have calculated the corrections for a free real scalar field -- both massive and massless -- and we have found that they increase, particularly for a massive field, at very high acceleration and vorticity and very low temperature. Finally, these non-ideal terms depend on the explicit form of the stress-energy operator, implying that different stress-energy tensor of the scalar field -- canonical or improved -- are thermodynamically inequivalent.
|
1412.7323
|
Maksym Tsizh
|
M. Tsizh, B. Novosyadlyj and Yu. Kulinich
|
Distribution of dark energy in the vicinity of compact objects
|
5 pages, 2 figures; WDS'14 Proceedings of Contributed Papers
|
WDS'14 Proceedings of Contributed Papers - Physics, 21-25, 2014
| null | null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The distribution of dark energy density in the vicinity of compact static
objects is analyzed. Dark energy is assumed to be in the form of a scalar field
with three parameters: the background density, the equation of state parameter
and the effective sound speed. Compact object is assumed to be a homogeneous
spherical object of constant radius. We use the solutions of the hydrodynamical
equations for dark energy in the gravitational fields of such objects for cases
of static distribution of dark energy in the vicinity of star and stationary
accretion onto black hole in order to analyze the possibility of constraining
of the parameters of dark energy from astrophysical data. We show that
dependence of density of dark energy in the vicinity of such object on the
effective sound speed, background density and equation of state parameter of
dark energy makes it possible to try such tests. Here we exploit the accuracy
of determination of masses of Sun and black hole in the center of Milky Way to
obtain the lower limit on the effective sound speed of dark energy.
|
[
{
"created": "Tue, 23 Dec 2014 11:20:07 GMT",
"version": "v1"
}
] |
2020-08-04
|
[
[
"Tsizh",
"M.",
""
],
[
"Novosyadlyj",
"B.",
""
],
[
"Kulinich",
"Yu.",
""
]
] |
The distribution of dark energy density in the vicinity of compact static objects is analyzed. Dark energy is assumed to be in the form of a scalar field with three parameters: the background density, the equation of state parameter and the effective sound speed. Compact object is assumed to be a homogeneous spherical object of constant radius. We use the solutions of the hydrodynamical equations for dark energy in the gravitational fields of such objects for cases of static distribution of dark energy in the vicinity of star and stationary accretion onto black hole in order to analyze the possibility of constraining of the parameters of dark energy from astrophysical data. We show that dependence of density of dark energy in the vicinity of such object on the effective sound speed, background density and equation of state parameter of dark energy makes it possible to try such tests. Here we exploit the accuracy of determination of masses of Sun and black hole in the center of Milky Way to obtain the lower limit on the effective sound speed of dark energy.
|
1310.5038
|
Rodrigo Maier
|
Rodrigo Maier, Francesco Pace and Ivano Dami\~ao Soares
|
Bounded Scalar Perturbations in Bouncing Brane World Cosmologies
|
15 pages, 29 figures. Accepted for publication in Physical Review D
|
Phys. Rev. D 88, 106003 (2013)
|
10.1103/PhysRevD.88.106003
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We examine the dynamics of scalar perturbations in closed
Friedmann-Lema\^itre-Robertson- Walker (FLRW) universes in the framework of
Brane World theory with a timelike extra dimension. In this scenario, the
unperturbed Friedmann equations contain additional terms arising from the
bulk-brane interaction that implement non-singular bounces in the models with a
cosmological constant and non-interacting perfect fluids. The structure of the
phase-space of the models allows for two basic configurations, namely, one
bounce solutions or eternal universes. Assuming that the matter content of the
model is given by dust and radiation, we derive the dynamical field equations
for scalar hydrodynamical perturbations considering either a conformally flat
(de Sitter) bulk or a perturbed bulk. We perform a numerical analysis which can
shed some light on the study of cosmological scalar perturbations in bouncing
brane world models. From a mathematical point of view we show that although the
bounce enhances the amplitudes of scalar perturbations for one bounce models in
the case of a de Sitter bulk, the amplitudes of the perturbations remain
sufficiently small and bounded relative to the background values up to a
certain scale. For one bounce models in the case of a perturbed bulk the
amplitudes of all perturbations (apart from the Weyl fluid energy density)
remain sufficiently small and bounded relative to the background values for any
scale of the perturbations. We also discuss and compare the stability and
bounded behaviour of the perturbations in the late accelerated phase of one
bounce solutions. For eternal universes we argue that some of these features
are maintained only for early times (typically of the order of the first
bounce). In this sense we show that eternal solutions are highly unstable
configurations considering the background model of this paper.
|
[
{
"created": "Fri, 18 Oct 2013 14:38:39 GMT",
"version": "v1"
}
] |
2014-12-16
|
[
[
"Maier",
"Rodrigo",
""
],
[
"Pace",
"Francesco",
""
],
[
"Soares",
"Ivano Damião",
""
]
] |
We examine the dynamics of scalar perturbations in closed Friedmann-Lema\^itre-Robertson- Walker (FLRW) universes in the framework of Brane World theory with a timelike extra dimension. In this scenario, the unperturbed Friedmann equations contain additional terms arising from the bulk-brane interaction that implement non-singular bounces in the models with a cosmological constant and non-interacting perfect fluids. The structure of the phase-space of the models allows for two basic configurations, namely, one bounce solutions or eternal universes. Assuming that the matter content of the model is given by dust and radiation, we derive the dynamical field equations for scalar hydrodynamical perturbations considering either a conformally flat (de Sitter) bulk or a perturbed bulk. We perform a numerical analysis which can shed some light on the study of cosmological scalar perturbations in bouncing brane world models. From a mathematical point of view we show that although the bounce enhances the amplitudes of scalar perturbations for one bounce models in the case of a de Sitter bulk, the amplitudes of the perturbations remain sufficiently small and bounded relative to the background values up to a certain scale. For one bounce models in the case of a perturbed bulk the amplitudes of all perturbations (apart from the Weyl fluid energy density) remain sufficiently small and bounded relative to the background values for any scale of the perturbations. We also discuss and compare the stability and bounded behaviour of the perturbations in the late accelerated phase of one bounce solutions. For eternal universes we argue that some of these features are maintained only for early times (typically of the order of the first bounce). In this sense we show that eternal solutions are highly unstable configurations considering the background model of this paper.
|
2107.13893
|
Kirill Bronnikov
|
Kirill A. Bronnikov, Sergey G. Rubin
|
Local regions with expanding extra dimensions
|
8 pages, 2 figures
| null | null | null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study possible spatial domains containing expanding extra dimensions. We
show that they are predicted in the framework of $f(R)$ gravity and could
appear due to quantum fluctuations during inflation. Their interior is
characterized by the multidimensional curvature ultimately tending to zero and
a slowly growing size of the extra dimensions.
|
[
{
"created": "Thu, 29 Jul 2021 10:56:17 GMT",
"version": "v1"
}
] |
2021-07-30
|
[
[
"Bronnikov",
"Kirill A.",
""
],
[
"Rubin",
"Sergey G.",
""
]
] |
We study possible spatial domains containing expanding extra dimensions. We show that they are predicted in the framework of $f(R)$ gravity and could appear due to quantum fluctuations during inflation. Their interior is characterized by the multidimensional curvature ultimately tending to zero and a slowly growing size of the extra dimensions.
|
gr-qc/0109026
|
Masaru Shibata
|
Masaru Shibata and Koji Uryu
|
Computation of gravitational waves from inspiraling binary neutron stars
in quasiequilibrium circular orbits : Formulation and calibration
|
26 pages, to be published in PRD
|
Phys.Rev. D64 (2001) 104017
|
10.1103/PhysRevD.64.104017
| null |
gr-qc
| null |
Gravitational waves from binary neutron stars in quasiequilibrium circular
orbits are computed using an approximate method which we propose in this paper.
In the first step of this method, we prepare general relativistic irrotational
binary neutron stars in a quasiequilibrium circular orbit, neglecting
gravitational waves. We adopt the so-called conformal flatness approximation
for a three-metric to obtain the quasiequilibrium states in this paper. In the
second step, we compute gravitational waves, solving linear perturbation
equations in the background spacetime of the quasiequilibrium states. Comparing
numerical results with post Newtonian waveforms and luminosity of gravitational
waves from two point masses in circular orbits, we demonstrate that this method
can produce accurate waveforms and luminosity of gravitational waves. It is
shown that the effects of tidal deformation of neutron stars and strong general
relativistic gravity modify the post Newtonian results for compact binary
neutron stars in close orbits. We indicate that the magnitude of a systematic
error in quasiequilibrium states associated with the conformal flatness
approximation is fairly large for close and compact binary neutron stars.
Several formulations for improving the accuracy of quasiequilibrium states are
proposed.
|
[
{
"created": "Fri, 7 Sep 2001 09:27:46 GMT",
"version": "v1"
}
] |
2009-11-07
|
[
[
"Shibata",
"Masaru",
""
],
[
"Uryu",
"Koji",
""
]
] |
Gravitational waves from binary neutron stars in quasiequilibrium circular orbits are computed using an approximate method which we propose in this paper. In the first step of this method, we prepare general relativistic irrotational binary neutron stars in a quasiequilibrium circular orbit, neglecting gravitational waves. We adopt the so-called conformal flatness approximation for a three-metric to obtain the quasiequilibrium states in this paper. In the second step, we compute gravitational waves, solving linear perturbation equations in the background spacetime of the quasiequilibrium states. Comparing numerical results with post Newtonian waveforms and luminosity of gravitational waves from two point masses in circular orbits, we demonstrate that this method can produce accurate waveforms and luminosity of gravitational waves. It is shown that the effects of tidal deformation of neutron stars and strong general relativistic gravity modify the post Newtonian results for compact binary neutron stars in close orbits. We indicate that the magnitude of a systematic error in quasiequilibrium states associated with the conformal flatness approximation is fairly large for close and compact binary neutron stars. Several formulations for improving the accuracy of quasiequilibrium states are proposed.
|
gr-qc/0008069
|
Francesco Fucito
|
F. Fucito
|
Deviations from Einstein's Gravity at Large and Short Distances
|
15 pages, 1 figure, talk delivered at the congress: Gravitational
Waves: A Challenge to Theoretical Astrophysics, Trieste June 2000 Addition of
a reference
| null | null | null |
gr-qc hep-th
| null |
In this talk I will describe some recent results on the sensitivity of
resonant mass detectors shaped as a hollow sphere to scalar gravitational
radiation. Detection of this type of gravitational radiation will signal
deviations from Einstein's gravity at large distances. I will then discuss a
class of experiments aiming at finding deviations from Einstein's gravity at
distances below 1 cm. I will review the main experimental difficulties in
performing such experiments and evaluate the effects to be taken in account.
|
[
{
"created": "Tue, 29 Aug 2000 11:48:03 GMT",
"version": "v1"
},
{
"created": "Thu, 31 Aug 2000 08:21:45 GMT",
"version": "v2"
}
] |
2007-05-23
|
[
[
"Fucito",
"F.",
""
]
] |
In this talk I will describe some recent results on the sensitivity of resonant mass detectors shaped as a hollow sphere to scalar gravitational radiation. Detection of this type of gravitational radiation will signal deviations from Einstein's gravity at large distances. I will then discuss a class of experiments aiming at finding deviations from Einstein's gravity at distances below 1 cm. I will review the main experimental difficulties in performing such experiments and evaluate the effects to be taken in account.
|
1010.2585
|
Dong-il Hwang
|
Dong-il Hwang and Dong-han Yeom
|
Internal structure of charged black holes
|
32 pages, 23 figures
|
Phys. Rev. D 84, 064020 (2011)
|
10.1103/PhysRevD.84.064020
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We investigate the internal structure of charged black holes with a
spherically symmetric model in the double-null coordinate system. Hawking
radiation is considered using the S-wave approximation of semiclassical
back-reaction and discharge is simulated by supplying an oppositely charged
matter to the black hole. In the stage of formation, the internal structure is
determined by the mass and charge of collapsing matter. When the charge-mass
ratio is small, a wormhole-like internal structure is observed. The structure
becomes analogous to the static limit as the ratio reaches unity. After the
formation, mass inflation induces large curvature in the internal structure,
which makes the structure insensitive to the late-time perturbations. The
internal structure determined from the formation seems to be maintained during
a substantial mass reduction. The discharge and neutralization of charged black
holes is also investigated for both non-evaporating and evaporating cases.
Finally, we discuss the implications of the wormhole-like structure inside of
charged black holes.
|
[
{
"created": "Wed, 13 Oct 2010 07:23:32 GMT",
"version": "v1"
},
{
"created": "Fri, 14 Oct 2011 20:00:38 GMT",
"version": "v2"
}
] |
2011-10-18
|
[
[
"Hwang",
"Dong-il",
""
],
[
"Yeom",
"Dong-han",
""
]
] |
We investigate the internal structure of charged black holes with a spherically symmetric model in the double-null coordinate system. Hawking radiation is considered using the S-wave approximation of semiclassical back-reaction and discharge is simulated by supplying an oppositely charged matter to the black hole. In the stage of formation, the internal structure is determined by the mass and charge of collapsing matter. When the charge-mass ratio is small, a wormhole-like internal structure is observed. The structure becomes analogous to the static limit as the ratio reaches unity. After the formation, mass inflation induces large curvature in the internal structure, which makes the structure insensitive to the late-time perturbations. The internal structure determined from the formation seems to be maintained during a substantial mass reduction. The discharge and neutralization of charged black holes is also investigated for both non-evaporating and evaporating cases. Finally, we discuss the implications of the wormhole-like structure inside of charged black holes.
|
2003.14016
|
Arun Kumar
|
Arun Kumar, Dharm Veer Singh, and Sushant G. Ghosh
|
Hayward black holes in Einstein-Gauss-Bonnet gravity
| null |
Annals of Physics 2020
|
10.1016/j.aop.2020.168214
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The Hayward metric is a spherically symmetric charged regular black holes, a
modification of the Reisnner-Nordstr$\ddot{o}$m black holes of Einstein's
equations coupled to nonlinear electrodynamics. We consider
Einstein-Gauss-Bonnet gravity (EGB) coupled to nonlinear electrodynamics to
present an exact five dimension ($5D$) Hayward black holes with a regular
center, having inner (Cauchy) and outer (event) horizons which go over to
Boulware-Desser black holes when the charge is switched off ($e=0$). The
presence of charge $e$ leads the modification in thermodynamical quantities,
and it has also been shown that the Hawking-Page like phase transition can be
achieved. The specific heat shows divergence at the horizon radius $r=r_C$
(critical radius), where the temperature has a maximum. Our result in the
limit, $e\to0$, reduces vis-a-vis to the $5D$ Boulware-Desser solutions.
|
[
{
"created": "Tue, 31 Mar 2020 08:16:19 GMT",
"version": "v1"
},
{
"created": "Wed, 1 Apr 2020 04:06:39 GMT",
"version": "v2"
}
] |
2020-06-03
|
[
[
"Kumar",
"Arun",
""
],
[
"Singh",
"Dharm Veer",
""
],
[
"Ghosh",
"Sushant G.",
""
]
] |
The Hayward metric is a spherically symmetric charged regular black holes, a modification of the Reisnner-Nordstr$\ddot{o}$m black holes of Einstein's equations coupled to nonlinear electrodynamics. We consider Einstein-Gauss-Bonnet gravity (EGB) coupled to nonlinear electrodynamics to present an exact five dimension ($5D$) Hayward black holes with a regular center, having inner (Cauchy) and outer (event) horizons which go over to Boulware-Desser black holes when the charge is switched off ($e=0$). The presence of charge $e$ leads the modification in thermodynamical quantities, and it has also been shown that the Hawking-Page like phase transition can be achieved. The specific heat shows divergence at the horizon radius $r=r_C$ (critical radius), where the temperature has a maximum. Our result in the limit, $e\to0$, reduces vis-a-vis to the $5D$ Boulware-Desser solutions.
|
2407.00484
|
Yen Chin Ong
|
Hengxin Lu, Sofia Di Gennaro, Yen Chin Ong
|
Generalized Entropy Implies Varying-G: Horizon Area Dependent Field
Equations and Black Hole-Cosmology Coupling
|
Minor changes; also added/fixed some references
| null | null | null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
When the Bekenstein-Hawking entropy is modified, ambiguity often arises
concerning whether the Hawking temperature or the thermodynamic mass should be
modified. The common practice, however, is to keep the black hole solution the
same as that in general relativity. On the other hand, if Jacobson's method of
deriving Einstein equations from thermodynamic is valid in the general
settings, then given a generalized entropy one should first derive the
corresponding modified gravity, and then look for the compatible black hole
solution before investigating its thermodynamics. We comment on some properties
and subtleties in this approach. In particular, we point out that generically
generalized entropy would lead to a varying effective gravitational "constant"
theory, where $G_\text{eff}$ depends on the horizon area. We discuss in what
ways such theories are discernible from general relativity despite its
seemingly jarring differences, and how to make sense of area-dependent field
equations. As a consequence we show that in the Jacobson's approach, the
standard quantum gravitational logarithmic correction to Bekenstein-Hawking
entropy is equivalent to a running gravitational "constant". A horizon area
dependent $G_\text{eff}$ could also lead to a coupling between black hole
masses and cosmological expansion, a scenario that has been studied recently in
the literature, but so far lacks strong theoretical motivation. In the Tsallis
case, we show that the thermodynamic mass for a Schwarzschild black hole is
just a constant multiple of its ADM mass, which is considerably simpler than
the approach not utilizing the Jacobson's method.
|
[
{
"created": "Sat, 29 Jun 2024 16:15:55 GMT",
"version": "v1"
},
{
"created": "Mon, 15 Jul 2024 03:53:40 GMT",
"version": "v2"
}
] |
2024-07-16
|
[
[
"Lu",
"Hengxin",
""
],
[
"Di Gennaro",
"Sofia",
""
],
[
"Ong",
"Yen Chin",
""
]
] |
When the Bekenstein-Hawking entropy is modified, ambiguity often arises concerning whether the Hawking temperature or the thermodynamic mass should be modified. The common practice, however, is to keep the black hole solution the same as that in general relativity. On the other hand, if Jacobson's method of deriving Einstein equations from thermodynamic is valid in the general settings, then given a generalized entropy one should first derive the corresponding modified gravity, and then look for the compatible black hole solution before investigating its thermodynamics. We comment on some properties and subtleties in this approach. In particular, we point out that generically generalized entropy would lead to a varying effective gravitational "constant" theory, where $G_\text{eff}$ depends on the horizon area. We discuss in what ways such theories are discernible from general relativity despite its seemingly jarring differences, and how to make sense of area-dependent field equations. As a consequence we show that in the Jacobson's approach, the standard quantum gravitational logarithmic correction to Bekenstein-Hawking entropy is equivalent to a running gravitational "constant". A horizon area dependent $G_\text{eff}$ could also lead to a coupling between black hole masses and cosmological expansion, a scenario that has been studied recently in the literature, but so far lacks strong theoretical motivation. In the Tsallis case, we show that the thermodynamic mass for a Schwarzschild black hole is just a constant multiple of its ADM mass, which is considerably simpler than the approach not utilizing the Jacobson's method.
|
gr-qc/0602001
|
Theodore A. Jacobson
|
Christopher Eling, Raf Guedens, Ted Jacobson
|
Non-equilibrium Thermodynamics of Spacetime
|
4 pages. Dedicated to Rafael Sorkin on the occasion of his 60th
birthday
|
Phys.Rev.Lett.96:121301,2006
|
10.1103/PhysRevLett.96.121301
| null |
gr-qc cond-mat.stat-mech hep-th quant-ph
| null |
It has previously been shown that the Einstein equation can be derived from
the requirement that the Clausius relation dS = dQ/T hold for all local
acceleration horizons through each spacetime point, where dS is one quarter the
horizon area change in Planck units, and dQ and T are the energy flux across
the horizon and Unruh temperature seen by an accelerating observer just inside
the horizon. Here we show that a curvature correction to the entropy that is
polynomial in the Ricci scalar requires a non-equilibrium treatment. The
corresponding field equation is derived from the entropy balance relation dS
=dQ/T+dS_i, where dS_i is a bulk viscosity entropy production term that we
determine by imposing energy-momentum conservation. Entropy production can also
be included in pure Einstein theory by allowing for shear viscosity of the
horizon.
|
[
{
"created": "Wed, 1 Feb 2006 06:30:50 GMT",
"version": "v1"
}
] |
2011-05-05
|
[
[
"Eling",
"Christopher",
""
],
[
"Guedens",
"Raf",
""
],
[
"Jacobson",
"Ted",
""
]
] |
It has previously been shown that the Einstein equation can be derived from the requirement that the Clausius relation dS = dQ/T hold for all local acceleration horizons through each spacetime point, where dS is one quarter the horizon area change in Planck units, and dQ and T are the energy flux across the horizon and Unruh temperature seen by an accelerating observer just inside the horizon. Here we show that a curvature correction to the entropy that is polynomial in the Ricci scalar requires a non-equilibrium treatment. The corresponding field equation is derived from the entropy balance relation dS =dQ/T+dS_i, where dS_i is a bulk viscosity entropy production term that we determine by imposing energy-momentum conservation. Entropy production can also be included in pure Einstein theory by allowing for shear viscosity of the horizon.
|
gr-qc/9903085
|
Modanese Giovanni
|
G. Modanese
|
Effect of a scale-dependent cosmological term on the motion of small
test particles in a Schwarzschild background
|
LaTeX, 13 pages
|
Nucl.Phys. B556 (1999) 397-408
|
10.1016/S0550-3213(99)00355-7
|
ECT*-99-2
|
gr-qc
| null |
It was recently suggested that the gravitational action could contain a
scale-dependent cosmological term, depending on the length or momentum scale
characteristic of the processes under consideration. In this work we explore a
simple possible consequence of this assumption. We compute the field generated
in empty space by a static spherical source (the Schwarzschild metric), using
the modified action. The resulting static potential turns out to contain a tiny
non-Newtonian component which depends on the size of the test particles. The
possible relevance of this small correction for the analysis of the recent
Pioneers data [J.D. Anderson et al., Phys. Rev. Lett. 81 (1998) 2858] is
briefly discussed.
|
[
{
"created": "Mon, 22 Mar 1999 19:13:56 GMT",
"version": "v1"
}
] |
2009-10-31
|
[
[
"Modanese",
"G.",
""
]
] |
It was recently suggested that the gravitational action could contain a scale-dependent cosmological term, depending on the length or momentum scale characteristic of the processes under consideration. In this work we explore a simple possible consequence of this assumption. We compute the field generated in empty space by a static spherical source (the Schwarzschild metric), using the modified action. The resulting static potential turns out to contain a tiny non-Newtonian component which depends on the size of the test particles. The possible relevance of this small correction for the analysis of the recent Pioneers data [J.D. Anderson et al., Phys. Rev. Lett. 81 (1998) 2858] is briefly discussed.
|
1904.12411
|
Sijie Gao
|
Xiaobao Wang, Xiaoning Wu, Sijie Gao
|
Critical phenomena in gravitational collapse of Husain-Martinez-Nunez
scalar field
|
14 pages, 6 figures
|
Eur.Phys.J.C (2019)79:823
|
10.1140/epjc/s10052-019-7340-0
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We construct analytical models to study the critical phenomena in
gravitational collapse of the Husain-Martinez-Nunez massless scalar field. We
first use the cut-and-paste technique to match the conformally flat solution
($c=0$ ) onto an outgoing Vaidya solution. To guarantee the continuity of the
metric and the extrinsic curvature, we prove that the two solutions must be
joined at a null hypersurface and the metric function in Vaidya spacetime must
satisfy some constraints. We find that the mass of the black hole in the
resulting spacetime takes the form $M\propto (p-p^*)^\gamma$, where the
critical exponent $\gamma$ is equal to $0.5$. For the case $c\neq 0$, we show
that the scalar field must be joined onto two pieces of Vaidya spacetimes to
avoid a naked singularity. We also derive the power-law mass formula with
$\gamma=0.5$. Compared with previous analytical models constructed from a
different scalar field with continuous self-similarity, we obtain the same
value of $\gamma$. However, we show that the solution with $c\neq 0$ is not
self-similar. Therefore, we provide a rare example that a scalar field without
self-similarity also possesses the features of critical collapse.
|
[
{
"created": "Mon, 29 Apr 2019 01:00:46 GMT",
"version": "v1"
}
] |
2019-10-28
|
[
[
"Wang",
"Xiaobao",
""
],
[
"Wu",
"Xiaoning",
""
],
[
"Gao",
"Sijie",
""
]
] |
We construct analytical models to study the critical phenomena in gravitational collapse of the Husain-Martinez-Nunez massless scalar field. We first use the cut-and-paste technique to match the conformally flat solution ($c=0$ ) onto an outgoing Vaidya solution. To guarantee the continuity of the metric and the extrinsic curvature, we prove that the two solutions must be joined at a null hypersurface and the metric function in Vaidya spacetime must satisfy some constraints. We find that the mass of the black hole in the resulting spacetime takes the form $M\propto (p-p^*)^\gamma$, where the critical exponent $\gamma$ is equal to $0.5$. For the case $c\neq 0$, we show that the scalar field must be joined onto two pieces of Vaidya spacetimes to avoid a naked singularity. We also derive the power-law mass formula with $\gamma=0.5$. Compared with previous analytical models constructed from a different scalar field with continuous self-similarity, we obtain the same value of $\gamma$. However, we show that the solution with $c\neq 0$ is not self-similar. Therefore, we provide a rare example that a scalar field without self-similarity also possesses the features of critical collapse.
|
2402.17320
|
Kamiel Janssens
|
Kamiel Janssens, Guillaume Boileau, Nelson Christensen, Nick van
Remortel, Francesca Badaracco, Benjamin Canuel, Alessandro Cardini, Andrea
Contu, Michael W. Coughlin, Jean-Baptiste Decitre, Rosario De Rosa, Matteo Di
Giovanni, Domenico D'Urso, St\'ephane Gaffet, Carlo Giunchi, Jan Harms,
Soumen Koley, Valentina Mangano, Luca Naticchioni, Marco Olivieri, Federico
Paoletti, Davide Rozza, Dylan O. Sabulsky, Shahar Shani-Kadmiel, Lucia Trozzo
|
Correlated 0.01Hz-40Hz seismic and Newtonian noise and its impact on
future gravitational-wave detectors
| null | null | null | null |
gr-qc astro-ph.IM physics.ins-det
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We report correlations in underground seismic measurements with horizontal
separations of several hundreds of meters to a few kilometers in the frequency
range 0.01Hz to 40Hz. These seismic correlations could threaten science goals
of planned interferometric gravitational-wave detectors such as the Einstein
Telescope as well as atom interferometers such as MIGA and ELGAR. We use
seismic measurements from four different sites, i.e. the former Homestake mine
(USA) as well as two candidate sites for the Einstein Telescope, Sos Enattos
(IT) and Euregio Maas-Rhein (NL-BE-DE) and the site housing the MIGA detector,
LSBB (FR). At all sites, we observe significant coherence for at least 50% of
the time in the majority of the frequency region of interest. Based on the
observed correlations in the seismic fields, we predict levels of correlated
Newtonian noise from body waves. We project the effect of correlated Newtonian
noise from body waves on the capabilities of the triangular design of the
Einstein Telescope's to observe an isotropic gravitational-wave background
(GWB) and find that, even in case of the most quiet site, its sensitivity will
be affected up to $\sim$20Hz. The resolvable amplitude of a GWB signal with a
negatively sloped power-law behaviour would be reduced by several orders of
magnitude. However, the resolvability of a power-law signal with a slope of
e.g. $\alpha=0$ ($\alpha=2/3$) would be more moderately affected by a factor
$\sim$ 6-9 ($\sim$3-4) in case of a low noise environment. Furthermore, we
bolster confidence in our results by showing that transient noise features have
a limited impact on the presented results.
|
[
{
"created": "Tue, 27 Feb 2024 08:52:32 GMT",
"version": "v1"
}
] |
2024-03-03
|
[
[
"Janssens",
"Kamiel",
""
],
[
"Boileau",
"Guillaume",
""
],
[
"Christensen",
"Nelson",
""
],
[
"van Remortel",
"Nick",
""
],
[
"Badaracco",
"Francesca",
""
],
[
"Canuel",
"Benjamin",
""
],
[
"Cardini",
"Alessandro",
""
],
[
"Contu",
"Andrea",
""
],
[
"Coughlin",
"Michael W.",
""
],
[
"Decitre",
"Jean-Baptiste",
""
],
[
"De Rosa",
"Rosario",
""
],
[
"Di Giovanni",
"Matteo",
""
],
[
"D'Urso",
"Domenico",
""
],
[
"Gaffet",
"Stéphane",
""
],
[
"Giunchi",
"Carlo",
""
],
[
"Harms",
"Jan",
""
],
[
"Koley",
"Soumen",
""
],
[
"Mangano",
"Valentina",
""
],
[
"Naticchioni",
"Luca",
""
],
[
"Olivieri",
"Marco",
""
],
[
"Paoletti",
"Federico",
""
],
[
"Rozza",
"Davide",
""
],
[
"Sabulsky",
"Dylan O.",
""
],
[
"Shani-Kadmiel",
"Shahar",
""
],
[
"Trozzo",
"Lucia",
""
]
] |
We report correlations in underground seismic measurements with horizontal separations of several hundreds of meters to a few kilometers in the frequency range 0.01Hz to 40Hz. These seismic correlations could threaten science goals of planned interferometric gravitational-wave detectors such as the Einstein Telescope as well as atom interferometers such as MIGA and ELGAR. We use seismic measurements from four different sites, i.e. the former Homestake mine (USA) as well as two candidate sites for the Einstein Telescope, Sos Enattos (IT) and Euregio Maas-Rhein (NL-BE-DE) and the site housing the MIGA detector, LSBB (FR). At all sites, we observe significant coherence for at least 50% of the time in the majority of the frequency region of interest. Based on the observed correlations in the seismic fields, we predict levels of correlated Newtonian noise from body waves. We project the effect of correlated Newtonian noise from body waves on the capabilities of the triangular design of the Einstein Telescope's to observe an isotropic gravitational-wave background (GWB) and find that, even in case of the most quiet site, its sensitivity will be affected up to $\sim$20Hz. The resolvable amplitude of a GWB signal with a negatively sloped power-law behaviour would be reduced by several orders of magnitude. However, the resolvability of a power-law signal with a slope of e.g. $\alpha=0$ ($\alpha=2/3$) would be more moderately affected by a factor $\sim$ 6-9 ($\sim$3-4) in case of a low noise environment. Furthermore, we bolster confidence in our results by showing that transient noise features have a limited impact on the presented results.
|
gr-qc/0612137
|
Joao Faria Martins
|
Jo\~ao Faria Martins, Aleksandar Mikovic
|
Invariants of Spin Networks Embedded in Three-Manifolds
|
29 pages, 9 figures; v2 small changes in the abstract
|
Commun.Math.Phys.279:381-399,2008
|
10.1007/s00220-008-0422-8
| null |
gr-qc hep-th math-ph math.MP math.QA
| null |
We study the invariants of spin networks embedded in a three-dimensional
manifold which are based on the path integral for SU(2) BF-Theory. These
invariants appear naturally in Loop Quantum Gravity, and have been defined as
spin-foam state sums. By using the Chain-Mail technique, we give a more general
definition of these invariants, and show that the state-sum definition is a
special case. This provides a rigorous proof that the state-sum invariants of
spin networks are topological invariants. We derive various results about the
BF-Theory spin network invariants, and we find a relation with the
corresponding invariants defined from Chern-Simons Theory, i.e. the
Witten-Reshetikhin-Turaev invariants. We also prove that the BF-Theory spin
network invariants coincide with V. Turaev's definition of invariants of
coloured graphs embedded in 3-manifolds and thick surfaces, constructed by
using shadow-world evaluations. Our framework therefore provides a unified view
of these invariants.
|
[
{
"created": "Thu, 21 Dec 2006 17:51:02 GMT",
"version": "v1"
},
{
"created": "Sat, 23 Dec 2006 13:45:35 GMT",
"version": "v2"
}
] |
2017-05-23
|
[
[
"Martins",
"João Faria",
""
],
[
"Mikovic",
"Aleksandar",
""
]
] |
We study the invariants of spin networks embedded in a three-dimensional manifold which are based on the path integral for SU(2) BF-Theory. These invariants appear naturally in Loop Quantum Gravity, and have been defined as spin-foam state sums. By using the Chain-Mail technique, we give a more general definition of these invariants, and show that the state-sum definition is a special case. This provides a rigorous proof that the state-sum invariants of spin networks are topological invariants. We derive various results about the BF-Theory spin network invariants, and we find a relation with the corresponding invariants defined from Chern-Simons Theory, i.e. the Witten-Reshetikhin-Turaev invariants. We also prove that the BF-Theory spin network invariants coincide with V. Turaev's definition of invariants of coloured graphs embedded in 3-manifolds and thick surfaces, constructed by using shadow-world evaluations. Our framework therefore provides a unified view of these invariants.
|
gr-qc/0104086
|
Giovanni Amelino-Camelia
|
Giovanni Amelino-Camelia
|
A phenomenological description of quantum-gravity-induced space-time
noise
|
10 pages, LaTex, 1 figure. Short paper, omitting most technical
details. More detailed analysis was reported in gr-qc/0104005
|
Nature 410:1065-1069,2001
|
10.1038/35074035
| null |
gr-qc
| null |
I propose a phenomenological description of space-time foam and discuss the
experimental limits that are within reach of forthcoming experiments.
|
[
{
"created": "Wed, 25 Apr 2001 20:29:10 GMT",
"version": "v1"
}
] |
2014-11-17
|
[
[
"Amelino-Camelia",
"Giovanni",
""
]
] |
I propose a phenomenological description of space-time foam and discuss the experimental limits that are within reach of forthcoming experiments.
|
1811.10639
|
Steffen Gielen
|
Steffen Gielen
|
Inhomogeneous universe from group field theory condensate
|
25 pages, 2 figures, revtex; v2: added a few comments and references,
version accepted in JCAP
|
JCAP 1902 (2019) 013
|
10.1088/1475-7516/2019/02/013
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
One of the fundamental challenges for quantum cosmology is to explain the
emergence of our macroscopic Universe from physics at the Planck scale. In the
group field theory (GFT) approach to quantum gravity, such a macroscopic
universe results from the formation of a "condensate" of fundamentally discrete
degrees of freedom. It has been shown that the effective dynamics of such GFT
condensates follows the classical Friedmann dynamics at late times, while
avoiding the classical singularity by a bounce akin to the one of loop quantum
cosmology (LQC). It was also shown how quantum fluctuations in a GFT condensate
provide an initial power spectrum of volume fluctuations around exact
homogeneity. Here we connect the results for quantum fluctuations in GFT to the
usual formalism for cosmological perturbations within quantum field theory in
curved spacetime. We consider a bouncing universe filled with a massless scalar
field, in which perturbations are generated by vacuum fluctuations in the
contracting phase. Matching conditions at the bounce are provided by working
within LQC. We then compare the results to the GFT condensate scenario for
quantum gravity with massless scalar matter. Here, instead, an initial quantum
phase described by a GFT condensate generates initial scalar perturbations
through quantum fluctuations. We show general agreement in the predictions of
both approaches, suggesting that GFT condensates can provide a physical
mechanism for the emergence of a slightly inhomogeneous universe from full
quantum gravity.
|
[
{
"created": "Mon, 26 Nov 2018 19:00:18 GMT",
"version": "v1"
},
{
"created": "Thu, 31 Jan 2019 11:41:28 GMT",
"version": "v2"
}
] |
2019-02-12
|
[
[
"Gielen",
"Steffen",
""
]
] |
One of the fundamental challenges for quantum cosmology is to explain the emergence of our macroscopic Universe from physics at the Planck scale. In the group field theory (GFT) approach to quantum gravity, such a macroscopic universe results from the formation of a "condensate" of fundamentally discrete degrees of freedom. It has been shown that the effective dynamics of such GFT condensates follows the classical Friedmann dynamics at late times, while avoiding the classical singularity by a bounce akin to the one of loop quantum cosmology (LQC). It was also shown how quantum fluctuations in a GFT condensate provide an initial power spectrum of volume fluctuations around exact homogeneity. Here we connect the results for quantum fluctuations in GFT to the usual formalism for cosmological perturbations within quantum field theory in curved spacetime. We consider a bouncing universe filled with a massless scalar field, in which perturbations are generated by vacuum fluctuations in the contracting phase. Matching conditions at the bounce are provided by working within LQC. We then compare the results to the GFT condensate scenario for quantum gravity with massless scalar matter. Here, instead, an initial quantum phase described by a GFT condensate generates initial scalar perturbations through quantum fluctuations. We show general agreement in the predictions of both approaches, suggesting that GFT condensates can provide a physical mechanism for the emergence of a slightly inhomogeneous universe from full quantum gravity.
|
1701.04330
|
Yong Cai
|
Yong Cai, Hai-Guang Li, Taotao Qiu, Yun-Song Piao
|
The Effective Field Theory of nonsingular cosmology: II
|
20 pages, 1 table, 9 figures; published in EPJC
|
Eur.Phys.J. C77 (2017) no.6, 369
|
10.1140/epjc/s10052-017-4938-y
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Based on the Effective Field Theory (EFT) of cosmological perturbations, we
explicitly clarify the pathology in nonsingular cubic Galileon models and show
how to cure it in EFT with new insights into this issue. With the least set of
EFT operators that are capable to avoid instabilities in nonsingular
cosmologies, we construct a nonsingular model dubbed the Genesis-inflation
model, in which a slowly expanding phase (namely, Genesis) with increasing
energy density is followed by slow-roll inflation. The spectrum of the
primordial perturbation may be simulated numerically, which shows itself a
large-scale cutoff, as the large-scale anomalies in CMB might be a hint for.
|
[
{
"created": "Mon, 16 Jan 2017 15:33:43 GMT",
"version": "v1"
},
{
"created": "Sat, 10 Jun 2017 15:18:58 GMT",
"version": "v2"
}
] |
2017-06-13
|
[
[
"Cai",
"Yong",
""
],
[
"Li",
"Hai-Guang",
""
],
[
"Qiu",
"Taotao",
""
],
[
"Piao",
"Yun-Song",
""
]
] |
Based on the Effective Field Theory (EFT) of cosmological perturbations, we explicitly clarify the pathology in nonsingular cubic Galileon models and show how to cure it in EFT with new insights into this issue. With the least set of EFT operators that are capable to avoid instabilities in nonsingular cosmologies, we construct a nonsingular model dubbed the Genesis-inflation model, in which a slowly expanding phase (namely, Genesis) with increasing energy density is followed by slow-roll inflation. The spectrum of the primordial perturbation may be simulated numerically, which shows itself a large-scale cutoff, as the large-scale anomalies in CMB might be a hint for.
|
gr-qc/0612157
|
Panayiotis Stavrinos
|
P.C.Stavrinos, A.P.Kouretsis, M.Stathakopoulos
|
Friedmann Robertson-Walker model in generalised metric space-time with
weak anisotropy
|
21 pages- to appear in GRG
|
Gen.Rel.Grav.40:1403-1425,2008
|
10.1007/s10714-007-0540-1
| null |
gr-qc
| null |
A generalized model of space-time is given, taking into consideration the
anisotropic structure of fields which are depended on the position and the
direction (velocity).In this framework a generalized FRW-metric the
Raychaudhouri and Friedmann equations are studied.A long range vector field of
cosmological origin is considered in relation to the physical geometry of
space-time in which Cartan connection has a fundamental role.The generalised
Friedmann equations are produced including anisotropic terms.The variation of
anisotropy $z_t$ is expressed in terms of the Cartan torsion tensor of the
Finslerian space-time.A possible estimation of the anisotropic parameter $z_t$
can be achieved with the aid of the de-Sitter model of the empty flat universe
with weak anisotropy. Finally a physical generalisation for the model of
inflation is also studied.
|
[
{
"created": "Sun, 24 Dec 2006 21:52:18 GMT",
"version": "v1"
},
{
"created": "Mon, 5 Feb 2007 13:58:04 GMT",
"version": "v2"
},
{
"created": "Mon, 16 Apr 2007 14:36:14 GMT",
"version": "v3"
},
{
"created": "Mon, 22 Oct 2007 18:18:27 GMT",
"version": "v4"
}
] |
2008-11-26
|
[
[
"Stavrinos",
"P. C.",
""
],
[
"Kouretsis",
"A. P.",
""
],
[
"Stathakopoulos",
"M.",
""
]
] |
A generalized model of space-time is given, taking into consideration the anisotropic structure of fields which are depended on the position and the direction (velocity).In this framework a generalized FRW-metric the Raychaudhouri and Friedmann equations are studied.A long range vector field of cosmological origin is considered in relation to the physical geometry of space-time in which Cartan connection has a fundamental role.The generalised Friedmann equations are produced including anisotropic terms.The variation of anisotropy $z_t$ is expressed in terms of the Cartan torsion tensor of the Finslerian space-time.A possible estimation of the anisotropic parameter $z_t$ can be achieved with the aid of the de-Sitter model of the empty flat universe with weak anisotropy. Finally a physical generalisation for the model of inflation is also studied.
|
0704.1567
|
Ragab Gad
|
Ragab M. Gad and A. Fouad
|
Energy and Momentum Distributions of Kantowski and Sachs Space-time
|
12 pages
|
Astrophys.SpaceSci.310:135-140,2007
|
10.1007/s10509-007-9488-6
| null |
gr-qc
| null |
We use the Einstein, Bergmann-Thomson, Landau-Lifshitz and Papapetrou
energy-momentum complexes to calculate the energy and momentum distributions of
Kantowski and Sachs space-time. We show that the Einstein and Bergmann-Thomson
definitions furnish a consistent result for the energy distribution, but the
definition of Landau-Lifshitz do not agree with them. We show that a signature
switch should affect about everything including energy distribution in the case
of Einstein and Papapetrou prescriptions but not in Bergmann-Thomson and
Landau-Lifshitz prescriptions.
|
[
{
"created": "Thu, 12 Apr 2007 11:53:55 GMT",
"version": "v1"
},
{
"created": "Sun, 15 Apr 2007 10:42:58 GMT",
"version": "v2"
}
] |
2008-11-26
|
[
[
"Gad",
"Ragab M.",
""
],
[
"Fouad",
"A.",
""
]
] |
We use the Einstein, Bergmann-Thomson, Landau-Lifshitz and Papapetrou energy-momentum complexes to calculate the energy and momentum distributions of Kantowski and Sachs space-time. We show that the Einstein and Bergmann-Thomson definitions furnish a consistent result for the energy distribution, but the definition of Landau-Lifshitz do not agree with them. We show that a signature switch should affect about everything including energy distribution in the case of Einstein and Papapetrou prescriptions but not in Bergmann-Thomson and Landau-Lifshitz prescriptions.
|
2407.21442
|
Francesco Iacovelli
|
Francesco Iacovelli and Michele Maggiore
|
Gravitational-wave observations and primordial black holes
|
To appear in the book "Primordial Black Holes", ed. Chris Byrnes,
Gabriele Franciolini, Tomohiro Harada, Paolo Pani, Misao Sasaki; Springer
(2024)
| null | null | null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Gravitational-wave observations have the potential of allowing the
identification of a population of merging primordial black-hole binaries. We
provide an overview of the capabilities of present and future GW detectors,
with a special emphasis on the perspective for observing quantities that are
signatures of a primordial origin.
|
[
{
"created": "Wed, 31 Jul 2024 08:45:29 GMT",
"version": "v1"
}
] |
2024-08-01
|
[
[
"Iacovelli",
"Francesco",
""
],
[
"Maggiore",
"Michele",
""
]
] |
Gravitational-wave observations have the potential of allowing the identification of a population of merging primordial black-hole binaries. We provide an overview of the capabilities of present and future GW detectors, with a special emphasis on the perspective for observing quantities that are signatures of a primordial origin.
|
0903.2021
|
Andrew Hamilton
|
Andrew J. S. Hamilton (JILA)
|
The interior structure of slowly rotating black holes
|
2 figures
|
Class.Quant.Grav.26:165006,2009
|
10.1088/0264-9381/26/16/165006
| null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The internal structure of a slowly rotating, charged black hole that is
undergoing mass inflation at its inner horizon is derived. The equations
governing the angular behavior decouple from the radial behavior, so all
conclusions regarding inflation in a spherical charged black hole carry through
unchanged for a slowly-rotating black hole. Quantities inflate only in the
radial direction, not in the angular direction. Exact self-similar solutions
are obtained. For sufficiently small accretion rates, the instantaneous angular
motion of the accretion flow has negligible effect on the angular spacetime
structure of the black hole, even if the instantaneous angular momentum of the
accretion flow is large and arbitrarily oriented.
|
[
{
"created": "Wed, 11 Mar 2009 18:02:52 GMT",
"version": "v1"
}
] |
2010-05-12
|
[
[
"Hamilton",
"Andrew J. S.",
"",
"JILA"
]
] |
The internal structure of a slowly rotating, charged black hole that is undergoing mass inflation at its inner horizon is derived. The equations governing the angular behavior decouple from the radial behavior, so all conclusions regarding inflation in a spherical charged black hole carry through unchanged for a slowly-rotating black hole. Quantities inflate only in the radial direction, not in the angular direction. Exact self-similar solutions are obtained. For sufficiently small accretion rates, the instantaneous angular motion of the accretion flow has negligible effect on the angular spacetime structure of the black hole, even if the instantaneous angular momentum of the accretion flow is large and arbitrarily oriented.
|
2001.01462
|
Cosmin Stachie
|
C. Stachie, T. Dal Canton, E. Burns, N. Christensen, R. Hamburg, M.
Briggs, J. Broida, A. Goldstein, F. Hayes, T. Littenberg, P. Shawhan, J.
Veitch, P. Veres, C. A. Wilson-Hodge
|
Search for Advanced LIGO Single Interferometer Compact Binary
Coalescence Signals in Coincidence with Gamma-Ray Events in Fermi-GBM
| null |
Class. Quantum Grav. 37 175001 (2020)
|
10.1088/1361-6382/aba28a
| null |
gr-qc astro-ph.HE
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Presented is the description of a new and general method used to search for
$\gamma$-ray counterparts to gravitational-wave (GW) triggers. This method is
specifically applied to single GW detector triggers. Advanced LIGO data from
observing runs O1 and O2 were analyzed, thus each GW trigger comes from either
the LIGO-Livingston or the LIGO-Hanford interferometer. For each GW trigger,
Fermi Gamma-ray Burst Monitor data is searched and the most significant
subthreshold signal counterpart is selected. Then, a methodology is defined in
order to establish which of GW-$\gamma$-ray pairs are likely to have a common
origin. For that purpose an association ranking statistic is calculated from
which a false alarm rate is derived. The events with the highest ranking
statistics are selected for further analysis consisting of LIGO detector
characterization and parameter estimation. The $\gamma$-ray signal
characteristics are also evaluated. We find no significant candidates from the
search.
|
[
{
"created": "Mon, 6 Jan 2020 10:09:38 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Jul 2020 13:18:58 GMT",
"version": "v2"
}
] |
2020-08-18
|
[
[
"Stachie",
"C.",
""
],
[
"Canton",
"T. Dal",
""
],
[
"Burns",
"E.",
""
],
[
"Christensen",
"N.",
""
],
[
"Hamburg",
"R.",
""
],
[
"Briggs",
"M.",
""
],
[
"Broida",
"J.",
""
],
[
"Goldstein",
"A.",
""
],
[
"Hayes",
"F.",
""
],
[
"Littenberg",
"T.",
""
],
[
"Shawhan",
"P.",
""
],
[
"Veitch",
"J.",
""
],
[
"Veres",
"P.",
""
],
[
"Wilson-Hodge",
"C. A.",
""
]
] |
Presented is the description of a new and general method used to search for $\gamma$-ray counterparts to gravitational-wave (GW) triggers. This method is specifically applied to single GW detector triggers. Advanced LIGO data from observing runs O1 and O2 were analyzed, thus each GW trigger comes from either the LIGO-Livingston or the LIGO-Hanford interferometer. For each GW trigger, Fermi Gamma-ray Burst Monitor data is searched and the most significant subthreshold signal counterpart is selected. Then, a methodology is defined in order to establish which of GW-$\gamma$-ray pairs are likely to have a common origin. For that purpose an association ranking statistic is calculated from which a false alarm rate is derived. The events with the highest ranking statistics are selected for further analysis consisting of LIGO detector characterization and parameter estimation. The $\gamma$-ray signal characteristics are also evaluated. We find no significant candidates from the search.
|
gr-qc/9704059
|
Bruce Bassett
|
Roy Maartens and Bruce A. Bassett
|
Gravito-electromagnetism
|
14 pages. Version to appear in Class. Quant. Grav
|
Class.Quant.Grav.15:705,1998
|
10.1088/0264-9381/15/3/018
| null |
gr-qc astro-ph hep-th
| null |
We develop and apply a fully covariant 1+3 electromagnetic analogy for
gravity. The free gravitational field is covariantly characterized by the Weyl
gravito-electric and gravito-magnetic spatial tensor fields, whose dynamical
equations are the Bianchi identities. Using a covariant generalization of
spatial vector algebra and calculus to spatial tensor fields, we exhibit the
covariant analogy between the tensor Bianchi equations and the vector Maxwell
equations. We identify gravitational source terms, couplings and potentials
with and without electromagnetic analogues. The nonlinear vacuum Bianchi
equations are shown to be invariant under covariant spatial duality rotation of
the gravito-electric and gravito-magnetic tensor fields. We construct the
super-energy density and super-Poynting vector of the gravitational field as
natural U(1) group invariants, and derive their super-energy conservation
equation. A covariant approach to gravito-electric/magnetic monopoles is also
presented.
|
[
{
"created": "Tue, 22 Apr 1997 19:03:41 GMT",
"version": "v1"
},
{
"created": "Tue, 2 Sep 1997 15:42:44 GMT",
"version": "v2"
},
{
"created": "Wed, 28 Jan 1998 01:19:06 GMT",
"version": "v3"
}
] |
2008-11-26
|
[
[
"Maartens",
"Roy",
""
],
[
"Bassett",
"Bruce A.",
""
]
] |
We develop and apply a fully covariant 1+3 electromagnetic analogy for gravity. The free gravitational field is covariantly characterized by the Weyl gravito-electric and gravito-magnetic spatial tensor fields, whose dynamical equations are the Bianchi identities. Using a covariant generalization of spatial vector algebra and calculus to spatial tensor fields, we exhibit the covariant analogy between the tensor Bianchi equations and the vector Maxwell equations. We identify gravitational source terms, couplings and potentials with and without electromagnetic analogues. The nonlinear vacuum Bianchi equations are shown to be invariant under covariant spatial duality rotation of the gravito-electric and gravito-magnetic tensor fields. We construct the super-energy density and super-Poynting vector of the gravitational field as natural U(1) group invariants, and derive their super-energy conservation equation. A covariant approach to gravito-electric/magnetic monopoles is also presented.
|
gr-qc/9910012
|
Thomas Thiemann
|
T. Thiemann
|
Canonical quantization of a minisuperspace model for gravity using
self-dual variables
|
4p, LATEX
|
Proceedings of the Cornelius Lanczos International Centenary
Conference, Raleigh, North Carolina, Dec. 12-17, 1993; J. D. Brown, M. T.
Chu, D. C. Ellison, R. J. Plemmons (Eds.), SIAM, Philadelphia, 1994
| null | null |
gr-qc
| null |
The present article summarizes the work of the papers \cite{1} dealing with
the quantization of pure gravity and gravity coupled to a Maxwell field and a
cosmological constant in presence of spherical symmetry. The class of models
presented is intended as an interesting testing ground for the quantization of
full 3+1 gravity. We are working in Ashtekar's self-dual representation.
|
[
{
"created": "Mon, 4 Oct 1999 17:54:24 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Thiemann",
"T.",
""
]
] |
The present article summarizes the work of the papers \cite{1} dealing with the quantization of pure gravity and gravity coupled to a Maxwell field and a cosmological constant in presence of spherical symmetry. The class of models presented is intended as an interesting testing ground for the quantization of full 3+1 gravity. We are working in Ashtekar's self-dual representation.
|
1010.3431
|
Yury F. Pirogov
|
Yu.F.Pirogov and I.Yu.Polev
|
Dark halos built of scalar gravitons: numerical study
|
11 pages. Report presented at The 16th Intern. Seminar on High Energy
Physics "Quarks-2010", Kolomna, Russia, 6 - 12 June, 2010
| null | null | null |
gr-qc hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In a previous article due to one of the present authors (YFP), an extension
to General Relativity, violating general covariance to the residual unimodular
one, was proposed. As a manifestation of such a violation, there appears the
(massive) scalar graviton in addition to the massless tensor one. The former
was proposed as a candidate on the dark matter in the Universe. In a subsequent
article (Yu. F. Pirogov, MPLA 24, 3239, 2009;arXiv:0909.3311 [gr-qc]), an
application of the extension was developed. Particularly, a regular solution to
the static spherically symmetric equations in empty space was studied by means
of analytical methods. This solution was proposed as a prototype model for the
galaxy soft-core dark halos, with the coherent scalar-graviton field as dark
matter. The present report is a supplement to the aforementioned article. The
statements of the latter are verified and visualized by means of numerical
analysis and symbolic calculations. The nice validity of analytical results is
found.
|
[
{
"created": "Sun, 17 Oct 2010 17:45:25 GMT",
"version": "v1"
}
] |
2010-10-19
|
[
[
"Pirogov",
"Yu. F.",
""
],
[
"Polev",
"I. Yu.",
""
]
] |
In a previous article due to one of the present authors (YFP), an extension to General Relativity, violating general covariance to the residual unimodular one, was proposed. As a manifestation of such a violation, there appears the (massive) scalar graviton in addition to the massless tensor one. The former was proposed as a candidate on the dark matter in the Universe. In a subsequent article (Yu. F. Pirogov, MPLA 24, 3239, 2009;arXiv:0909.3311 [gr-qc]), an application of the extension was developed. Particularly, a regular solution to the static spherically symmetric equations in empty space was studied by means of analytical methods. This solution was proposed as a prototype model for the galaxy soft-core dark halos, with the coherent scalar-graviton field as dark matter. The present report is a supplement to the aforementioned article. The statements of the latter are verified and visualized by means of numerical analysis and symbolic calculations. The nice validity of analytical results is found.
|
2407.07864
|
Boran Yesilyurt
|
S. P. Miao (NCKU), N. C. Tsamis (U. of Crete), R. P. Woodard (U. of
Florida), B. Yesilyurt (U. of Florida)
|
The Third Structure Function
|
17 pages, 5 Tables , uses LaTeX2e
| null | null |
CCTP-2024-8, UFIFT-QG-24-05
|
gr-qc hep-th
|
http://creativecommons.org/licenses/by/4.0/
|
We re-consider the graviton self-energy induced by a loop of massless,
minimally coupled scalars on de Sitter background. On flat space background it
can be represented as a sum of two tensor differential operators acting on
scalar structure functions. On a general background these tensor differential
operators can be constructed from the linearized Ricci scalar and the
linearized Weyl tensor. However, in cosmology one requires a third contribution
which we derive here.
|
[
{
"created": "Wed, 10 Jul 2024 17:26:21 GMT",
"version": "v1"
}
] |
2024-07-11
|
[
[
"Miao",
"S. P.",
"",
"NCKU"
],
[
"Tsamis",
"N. C.",
"",
"U. of Crete"
],
[
"Woodard",
"R. P.",
"",
"U. of\n Florida"
],
[
"Yesilyurt",
"B.",
"",
"U. of Florida"
]
] |
We re-consider the graviton self-energy induced by a loop of massless, minimally coupled scalars on de Sitter background. On flat space background it can be represented as a sum of two tensor differential operators acting on scalar structure functions. On a general background these tensor differential operators can be constructed from the linearized Ricci scalar and the linearized Weyl tensor. However, in cosmology one requires a third contribution which we derive here.
|
2010.04571
|
Jinsong Yang
|
Jinsong Yang, Cong Zhang, Yongge Ma
|
Loop quantum cosmology from an alternative Hamiltonian. II. Including
the Lorentzian term
|
12 pages, 5 figures
|
Phys. Rev. D 102, 084018 (2020)
|
10.1103/PhysRevD.102.084018
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The scheme of using the Chern-Simons action to regularize the gravitational
Hamiltonian constraint is extended to including the Lorentzian term in the
$k=0$ cosmological model. The Euclidean term and the Lorenzian term are thus
regularized separately mimicking the treatment of full loop quantum gravity.
The new quantum dynamics for the spatially flat Friedmann-Robertson-Walker
model with a massless scalar field as an emergent time is studied. By
semiclassical analysis, the effective Hamiltonian constraint is obtained, which
indicates that the new quantum dynamics has the correct classical limit. The
classical big-bang singularity is again replaced by a quantum bounce. Similar
to the case of quantizing only the Euclidean term, the backward evolution of
the cosmological model determined by the new effective Hamiltonian will be
bounced to an asymptotic de Sitter universe coupled to a massless scalar field,
while the problem of negative energy density of matter in the former case is
resolved.
|
[
{
"created": "Fri, 9 Oct 2020 13:36:38 GMT",
"version": "v1"
}
] |
2020-10-12
|
[
[
"Yang",
"Jinsong",
""
],
[
"Zhang",
"Cong",
""
],
[
"Ma",
"Yongge",
""
]
] |
The scheme of using the Chern-Simons action to regularize the gravitational Hamiltonian constraint is extended to including the Lorentzian term in the $k=0$ cosmological model. The Euclidean term and the Lorenzian term are thus regularized separately mimicking the treatment of full loop quantum gravity. The new quantum dynamics for the spatially flat Friedmann-Robertson-Walker model with a massless scalar field as an emergent time is studied. By semiclassical analysis, the effective Hamiltonian constraint is obtained, which indicates that the new quantum dynamics has the correct classical limit. The classical big-bang singularity is again replaced by a quantum bounce. Similar to the case of quantizing only the Euclidean term, the backward evolution of the cosmological model determined by the new effective Hamiltonian will be bounced to an asymptotic de Sitter universe coupled to a massless scalar field, while the problem of negative energy density of matter in the former case is resolved.
|
gr-qc/0608086
|
David Finkelstein
|
David Ritz Finkelstein
|
Homotopy approach to quantum gravity
|
For International Journal of Theoretical Physics, Oberwolfach 2006
issue
|
Int.J.Theor.Phys.47:534-552,2008
|
10.1007/s10773-007-9479-y
| null |
gr-qc
| null |
I construct a finite-dimensional quantum theory from general relativity by a
homotopy method. Its quantum history is made up of at least two levels of
fermionic elements. Its unitary group has the diffeomorphism group as singular
limit. Its gravitational metrical form is the algebraic square. Its spinors are
multivectors.
|
[
{
"created": "Fri, 18 Aug 2006 18:43:37 GMT",
"version": "v1"
}
] |
2008-11-26
|
[
[
"Finkelstein",
"David Ritz",
""
]
] |
I construct a finite-dimensional quantum theory from general relativity by a homotopy method. Its quantum history is made up of at least two levels of fermionic elements. Its unitary group has the diffeomorphism group as singular limit. Its gravitational metrical form is the algebraic square. Its spinors are multivectors.
|
0904.0999
|
Sam Dolan Dr
|
Luis C. B. Crispino, Sam R. Dolan and Ednilton S. Oliveira
|
Scattering of massless scalar waves by Reissner-Nordstr\"om black holes
|
9 pages, 10 figures
|
Phys.Rev.D79:064022,2009
|
10.1103/PhysRevD.79.064022
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present a study of scattering of massless planar scalar waves by a charged
non-rotating black hole. Partial wave methods are applied to compute scattering
and absorption cross sections, for a range of incident wavelengths. We compare
our numerical results with semi-classical approximations from a geodesic
analysis, and find excellent agreement. The glory in the backward direction is
studied, and its properties are shown to be related to the properties of the
photon orbit. The effects of black hole charge upon scattering and absorption
are examined in detail. As the charge of the black hole is increased, we find
that the absorption cross section decreases, and the angular width of the
interference fringes of the scattering cross section at large angles increases.
In particular, the glory spot in the backward direction becomes wider. We
interpret these effects under the light of our geodesic analysis.
|
[
{
"created": "Mon, 6 Apr 2009 20:02:58 GMT",
"version": "v1"
}
] |
2015-05-13
|
[
[
"Crispino",
"Luis C. B.",
""
],
[
"Dolan",
"Sam R.",
""
],
[
"Oliveira",
"Ednilton S.",
""
]
] |
We present a study of scattering of massless planar scalar waves by a charged non-rotating black hole. Partial wave methods are applied to compute scattering and absorption cross sections, for a range of incident wavelengths. We compare our numerical results with semi-classical approximations from a geodesic analysis, and find excellent agreement. The glory in the backward direction is studied, and its properties are shown to be related to the properties of the photon orbit. The effects of black hole charge upon scattering and absorption are examined in detail. As the charge of the black hole is increased, we find that the absorption cross section decreases, and the angular width of the interference fringes of the scattering cross section at large angles increases. In particular, the glory spot in the backward direction becomes wider. We interpret these effects under the light of our geodesic analysis.
|
gr-qc/9601023
|
Aharon Davidson
|
Aharon Davidson and Uzi Paz
|
Extensible Black Hole Embeddings for Apparently Forbidden Periodicities
|
11 pages, RevTex file, 1 postcript figure
|
Foundations of Physics 30, 5 (2000)
|
10.1023/A:1003793128801
| null |
gr-qc hep-th
| null |
Imposing extendibility on Kasner-Fronsdal black hole local isometric
embedding is equivalent to removing conic singularities in Kruskal
representation. Allowing for globally non-trivial (living in $M_{5}\times
S_{1}$) embeddings, parameterized by $k$, extendibility can be achieved for
apparently forbidden frequencies $\omega_{1}(k)\le\omega (k)\le \omega_{2}(k)$.
The Hawking-Gibbons limit, say $\displaystyle{\omega_{1,2}(0)= {1\over{4M}}}$
for Schwarzschild geometry, is respected. The corresponding Kruskal sheets are
viewed as slices in some Kaluza-Klein background. Euclidean $k$ discreteness,
dictated by imaginary time periodicity, is correlated with twistor flux
quantization.
|
[
{
"created": "Tue, 16 Jan 1996 12:12:25 GMT",
"version": "v1"
}
] |
2019-11-04
|
[
[
"Davidson",
"Aharon",
""
],
[
"Paz",
"Uzi",
""
]
] |
Imposing extendibility on Kasner-Fronsdal black hole local isometric embedding is equivalent to removing conic singularities in Kruskal representation. Allowing for globally non-trivial (living in $M_{5}\times S_{1}$) embeddings, parameterized by $k$, extendibility can be achieved for apparently forbidden frequencies $\omega_{1}(k)\le\omega (k)\le \omega_{2}(k)$. The Hawking-Gibbons limit, say $\displaystyle{\omega_{1,2}(0)= {1\over{4M}}}$ for Schwarzschild geometry, is respected. The corresponding Kruskal sheets are viewed as slices in some Kaluza-Klein background. Euclidean $k$ discreteness, dictated by imaginary time periodicity, is correlated with twistor flux quantization.
|
1303.6157
|
Yaser Tavakoli
|
Yaser Tavakoli, Joao Marto and Andrea Dapor
|
Semiclassical dynamics of horizons in spherically symmetric collapse
|
Version accepted in IJMPD
|
Int. J. Mod. Phys. D 23 (2014) 1450061
|
10.1142/S0218271814500618
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this work, we consider a semiclassical description of the spherically
symmetric gravitational collapse with a massless scalar field. In particular,
we employ an effective scenario provided by holonomy corrections from loop
quantum gravity, to the homogeneous interior spacetime. The singularity that
would arise at the final stage of the corresponding classical collapse, is
resolved in this context and is replaced by a bounce. Our main purpose is to
investigate the evolution of trapped surfaces during this semiclassical
collapse. Within this setting, we obtain a threshold radius for the collapsing
shells in order to have horizons formation. In addition, we study the final
state of the collapse by employing a suitable matching at the boundary shell
from which quantum gravity effects are carried to the exterior geometry.
|
[
{
"created": "Mon, 25 Mar 2013 15:12:42 GMT",
"version": "v1"
},
{
"created": "Fri, 20 Sep 2013 21:48:15 GMT",
"version": "v2"
},
{
"created": "Wed, 30 Apr 2014 13:25:51 GMT",
"version": "v3"
}
] |
2014-05-21
|
[
[
"Tavakoli",
"Yaser",
""
],
[
"Marto",
"Joao",
""
],
[
"Dapor",
"Andrea",
""
]
] |
In this work, we consider a semiclassical description of the spherically symmetric gravitational collapse with a massless scalar field. In particular, we employ an effective scenario provided by holonomy corrections from loop quantum gravity, to the homogeneous interior spacetime. The singularity that would arise at the final stage of the corresponding classical collapse, is resolved in this context and is replaced by a bounce. Our main purpose is to investigate the evolution of trapped surfaces during this semiclassical collapse. Within this setting, we obtain a threshold radius for the collapsing shells in order to have horizons formation. In addition, we study the final state of the collapse by employing a suitable matching at the boundary shell from which quantum gravity effects are carried to the exterior geometry.
|
gr-qc/0401093
|
Juan Manuel Garcia-Islas
|
J.Manuel Garcia-Islas
|
Observables in 3-dimensional quantum gravity and topological invariants
|
24 pages, 47 figures
|
Class.Quant.Grav. 21 (2004) 3933-3952
|
10.1088/0264-9381/21/16/008
| null |
gr-qc hep-th
| null |
In this paper we report some results on the expectation values of a set of
observables introduced for 3-dimensional Riemannian quantum gravity with
positive cosmological constant, that is, observables in the Turaev-Viro model.
Instead of giving a formal description of the observables, we just formulate
the paper by examples. This means that we just show how an idea works with
particular cases and give a way to compute 'expectation values' in general by a
topological procedure.
|
[
{
"created": "Wed, 21 Jan 2004 22:46:50 GMT",
"version": "v1"
}
] |
2009-11-10
|
[
[
"Garcia-Islas",
"J. Manuel",
""
]
] |
In this paper we report some results on the expectation values of a set of observables introduced for 3-dimensional Riemannian quantum gravity with positive cosmological constant, that is, observables in the Turaev-Viro model. Instead of giving a formal description of the observables, we just formulate the paper by examples. This means that we just show how an idea works with particular cases and give a way to compute 'expectation values' in general by a topological procedure.
|
gr-qc/0511104
|
Yun Soo Myung
|
Yun Soo Myung
|
Entanglement system, Casimir energy and black hole
|
11 pages, no figure, version to appear in PLB
|
Phys.Lett. B636 (2006) 324-329
|
10.1016/j.physletb.2006.03.070
|
INJE-TP-05-08
|
gr-qc hep-th
| null |
We investigate the connection between the entanglement system in Minkowski
spacetime and the black hole using the scaling analysis. Here we show that the
entanglement system satisfies the Bekenstein entropy bound. Even though the
entropies of two systems are the same form, the entanglement energy is
different from the black hole energy. Introducing the Casimir energy of the
vacuum energy fluctuations rather than the entanglement energy, it shows a
feature of the black hole energy. Hence the Casimir energy is more close to the
black hole than the entanglement energy. Finally, we find that the entanglement
system behaves like the black hole if the gravitational effects are included
properly.
|
[
{
"created": "Thu, 17 Nov 2005 19:06:55 GMT",
"version": "v1"
},
{
"created": "Tue, 4 Apr 2006 15:14:26 GMT",
"version": "v2"
}
] |
2010-04-05
|
[
[
"Myung",
"Yun Soo",
""
]
] |
We investigate the connection between the entanglement system in Minkowski spacetime and the black hole using the scaling analysis. Here we show that the entanglement system satisfies the Bekenstein entropy bound. Even though the entropies of two systems are the same form, the entanglement energy is different from the black hole energy. Introducing the Casimir energy of the vacuum energy fluctuations rather than the entanglement energy, it shows a feature of the black hole energy. Hence the Casimir energy is more close to the black hole than the entanglement energy. Finally, we find that the entanglement system behaves like the black hole if the gravitational effects are included properly.
|
gr-qc/0012015
|
Sawa Manoff
|
S. Manoff
|
Deviation equations of Synge and Schild over spaces with affine
connections and metrics
|
15 pages, LaTeX. To appear in Intern. J. Mod. Phys. A
|
Int.J.Mod.Phys. A16 (2001) 1109-1122
|
10.1142/S0217751X01003068
| null |
gr-qc
| null |
Deviation equation of Synge and Schild has been investigated over spaces with
affine connections and metrics. It is shown that the condition for the
vanishing of the Lie derivative of a vector field along a given non-null
(non-isotropic) vector field u for obtaining this equation is only a sufficient
(but not necessary) condition. By means of the vector field u and the
projective metric (orthogonal to it) projected deviation equations of Synge and
Schild have been obtained for a vector field, orthogonal to the given vector
field u, as well as for the square of its length. For a given non-isotropic,
auto-parallel and normalized vector field u this equation could have some
simple solutions.
PACS numbers: 02.90; 04.50+h; 04.90.+e: 04.30.+x
|
[
{
"created": "Tue, 5 Dec 2000 07:31:44 GMT",
"version": "v1"
}
] |
2015-06-25
|
[
[
"Manoff",
"S.",
""
]
] |
Deviation equation of Synge and Schild has been investigated over spaces with affine connections and metrics. It is shown that the condition for the vanishing of the Lie derivative of a vector field along a given non-null (non-isotropic) vector field u for obtaining this equation is only a sufficient (but not necessary) condition. By means of the vector field u and the projective metric (orthogonal to it) projected deviation equations of Synge and Schild have been obtained for a vector field, orthogonal to the given vector field u, as well as for the square of its length. For a given non-isotropic, auto-parallel and normalized vector field u this equation could have some simple solutions. PACS numbers: 02.90; 04.50+h; 04.90.+e: 04.30.+x
|
1901.09870
|
Christy Kelly
|
Christy Kelly, Carlo A Trugenberger and Fabio Biancalana
|
Self-Assembly of Geometric Space from Random Graphs
|
26 pages, 9 figures, 2 appendices
|
Classical and Quantum Gravity, 2019
|
10.1088/1361-6382/ab1c7d
| null |
gr-qc cond-mat.stat-mech hep-th math.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present a Euclidean quantum gravity model in which random graphs
dynamically self-assemble into discrete manifold structures. Concretely, we
consider a statistical model driven by a discretisation of the Euclidean
Einstein-Hilbert action; contrary to previous approaches based on simplicial
complexes and Regge calculus our discretisation is based on the Ollivier
curvature, a coarse analogue of the manifold Ricci curvature defined for
generic graphs. The Ollivier curvature is generally difficult to evaluate due
to its definition in terms of optimal transport theory, but we present a new
exact expression for the Ollivier curvature in a wide class of relevant graphs
purely in terms of the numbers of short cycles at an edge. This result should
be of independent intrinsic interest to network theorists. Action minimising
configurations prove to be cubic complexes up to defects; there are indications
that such defects are dynamically suppressed in the macroscopic limit. Closer
examination of a defect free model shows that certain classical configurations
have a geometric interpretation and discretely approximate vacuum solutions to
the Euclidean Einstein-Hilbert action. Working in a configuration space where
the geometric configurations are stable vacua of the theory, we obtain direct
numerical evidence for the existence of a continuous phase transition; this
makes the model a UV completion of Euclidean Einstein gravity. Notably, this
phase transition implies an area-law for the entropy of emerging geometric
space. Certain vacua of the theory can be interpreted as baby universes; we
find that these configurations appear as stable vacua in a mean field
approximation of our model, but are excluded dynamically whenever the action is
exact indicating the dynamical stability of geometric space. The model is
intended as a setting for subsequent studies of emergent time mechanisms.
|
[
{
"created": "Mon, 28 Jan 2019 18:24:44 GMT",
"version": "v1"
},
{
"created": "Tue, 30 Apr 2019 13:56:38 GMT",
"version": "v2"
}
] |
2019-05-01
|
[
[
"Kelly",
"Christy",
""
],
[
"Trugenberger",
"Carlo A",
""
],
[
"Biancalana",
"Fabio",
""
]
] |
We present a Euclidean quantum gravity model in which random graphs dynamically self-assemble into discrete manifold structures. Concretely, we consider a statistical model driven by a discretisation of the Euclidean Einstein-Hilbert action; contrary to previous approaches based on simplicial complexes and Regge calculus our discretisation is based on the Ollivier curvature, a coarse analogue of the manifold Ricci curvature defined for generic graphs. The Ollivier curvature is generally difficult to evaluate due to its definition in terms of optimal transport theory, but we present a new exact expression for the Ollivier curvature in a wide class of relevant graphs purely in terms of the numbers of short cycles at an edge. This result should be of independent intrinsic interest to network theorists. Action minimising configurations prove to be cubic complexes up to defects; there are indications that such defects are dynamically suppressed in the macroscopic limit. Closer examination of a defect free model shows that certain classical configurations have a geometric interpretation and discretely approximate vacuum solutions to the Euclidean Einstein-Hilbert action. Working in a configuration space where the geometric configurations are stable vacua of the theory, we obtain direct numerical evidence for the existence of a continuous phase transition; this makes the model a UV completion of Euclidean Einstein gravity. Notably, this phase transition implies an area-law for the entropy of emerging geometric space. Certain vacua of the theory can be interpreted as baby universes; we find that these configurations appear as stable vacua in a mean field approximation of our model, but are excluded dynamically whenever the action is exact indicating the dynamical stability of geometric space. The model is intended as a setting for subsequent studies of emergent time mechanisms.
|
2404.16981
|
Giulio Neri
|
Giulio Neri and Stefano Liberati
|
Covariant phase space analysis of Lanczos-Lovelock gravity with
boundaries
|
38 pages, 2 figures; references added, minor rephrasing
| null | null | null |
gr-qc hep-th
|
http://creativecommons.org/publicdomain/zero/1.0/
|
This work introduces a novel prescription for the expression of the
thermodynamic potentials associated with the couplings of a Lanczos-Lovelock
theory. These potentials emerge in theories with multiple couplings, where the
ratio between them provide intrinsic length scales that break scale invariance.
Our prescription, derived from the covariant phase space formalism, differs
from previous approaches by enabling the construction of finite potentials
without reference to any background. To do so, we consistently work with
finite-size systems with Dirichlet boundary conditions and rigorously take into
account boundary and corner terms: including these terms is found to be crucial
for relaxing the integrability conditions for phase space quantities that were
required in previous works. We apply this prescription to the first law of
(extended) thermodynamics for stationary black holes, and derive a version of
the Smarr formula that holds for static black holes with arbitrary asymptotic
behaviour.
|
[
{
"created": "Thu, 25 Apr 2024 19:13:55 GMT",
"version": "v1"
},
{
"created": "Tue, 14 May 2024 14:34:24 GMT",
"version": "v2"
}
] |
2024-05-15
|
[
[
"Neri",
"Giulio",
""
],
[
"Liberati",
"Stefano",
""
]
] |
This work introduces a novel prescription for the expression of the thermodynamic potentials associated with the couplings of a Lanczos-Lovelock theory. These potentials emerge in theories with multiple couplings, where the ratio between them provide intrinsic length scales that break scale invariance. Our prescription, derived from the covariant phase space formalism, differs from previous approaches by enabling the construction of finite potentials without reference to any background. To do so, we consistently work with finite-size systems with Dirichlet boundary conditions and rigorously take into account boundary and corner terms: including these terms is found to be crucial for relaxing the integrability conditions for phase space quantities that were required in previous works. We apply this prescription to the first law of (extended) thermodynamics for stationary black holes, and derive a version of the Smarr formula that holds for static black holes with arbitrary asymptotic behaviour.
|
0808.1687
|
Mark D. Roberts
|
Mark D. Roberts
|
The Lanczos potential and Chern-Simons theory
|
15 pages
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A new tensor $D$ is introduced which is constructed from the Lanczos
potential and is of the same form as that of the Weyl tensor $C$ expressed in
terms of the Lanczos potential except that covariant differentiation is
replaced by transvection with a vector $v$. The new tensor has associated
invariants $C\cdot D$ and $D^2$, the first of these can be interpreted as a
Chern-Simons term for Weyl $C^2$ gravity. Both invariants allow various tensors
to be constructed and some of the properties of these are investigated by using
exact examples.
|
[
{
"created": "Tue, 12 Aug 2008 15:48:33 GMT",
"version": "v1"
}
] |
2008-08-13
|
[
[
"Roberts",
"Mark D.",
""
]
] |
A new tensor $D$ is introduced which is constructed from the Lanczos potential and is of the same form as that of the Weyl tensor $C$ expressed in terms of the Lanczos potential except that covariant differentiation is replaced by transvection with a vector $v$. The new tensor has associated invariants $C\cdot D$ and $D^2$, the first of these can be interpreted as a Chern-Simons term for Weyl $C^2$ gravity. Both invariants allow various tensors to be constructed and some of the properties of these are investigated by using exact examples.
|
1104.2218
|
Cosimo Bambi
|
Cosimo Bambi
|
Compact objects with spin parameter $a_* > 1$
|
4 pages, 1 figure. Talk given at "46th Rencontres de Moriond:
Gravitational Waves and Experimental Gravity", 20 - 27 March 2011, La Thuile,
Aosta, Italy. To appear in the conference proceedings
| null | null |
IPMU11-0055
|
gr-qc astro-ph.HE
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In 4-dimensional General Relativity, black holes are described by the Kerr
solution and are completely specified by their mass $M$ and by their spin
angular momentum $J$. A fundamental limit for a black hole in General
Relativity is the Kerr bound $|a_*| \le 1$, where $a_* = J/M^2$ is the spin
parameter. Future experiments will be able to probe the geometry around these
objects and test the Kerr black hole hypothesis. Interestingly, if these
objects are not black holes, the accretion process may spin them up to $a_* >
1$.
|
[
{
"created": "Tue, 12 Apr 2011 14:11:25 GMT",
"version": "v1"
}
] |
2011-04-13
|
[
[
"Bambi",
"Cosimo",
""
]
] |
In 4-dimensional General Relativity, black holes are described by the Kerr solution and are completely specified by their mass $M$ and by their spin angular momentum $J$. A fundamental limit for a black hole in General Relativity is the Kerr bound $|a_*| \le 1$, where $a_* = J/M^2$ is the spin parameter. Future experiments will be able to probe the geometry around these objects and test the Kerr black hole hypothesis. Interestingly, if these objects are not black holes, the accretion process may spin them up to $a_* > 1$.
|
1008.5219
|
Wen-Biao Han
|
Wen-Biao Han
|
Comment on "Is a Circular Orbit Possible According to General
Relativity?" (arXiv:1008.3553v1)
|
4 pages, 3 figures
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
This is a comment on `` Is a Circular Orbit Possible According to General
Relativity?" by F. T. Hioe and D. Kuebel.
|
[
{
"created": "Tue, 31 Aug 2010 05:19:19 GMT",
"version": "v1"
}
] |
2010-09-01
|
[
[
"Han",
"Wen-Biao",
""
]
] |
This is a comment on `` Is a Circular Orbit Possible According to General Relativity?" by F. T. Hioe and D. Kuebel.
|
0809.2469
|
Jakub Mielczarek
|
Jakub Mielczarek
|
Multi-fluid potential in the loop cosmology
|
6 pages, 6 figures, new section on perturbations added. Version to
appear in PLB
|
Phys.Lett.B675:273-278,2009
|
10.1016/j.physletb.2009.04.034
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The scalar field can behave like a fluid with equation of state
$p_{\phi}=w\rho_{\phi}$, where $w \in [-1,1]$. In this Letter we derive a class
of the scalar field potentials for which $w=$ const. Scalar field with such a
potential can mimic ordinary matter, radiation, cosmic strings, etc. We perform
our calculations in the framework of the loop cosmology with holonomy
corrections. We solve the model analytically for the whole parameter space.
Subsequently, we perform similar consideration for the model with a phantom
field ($w<-1$). We show that scalar field is monotonic function in both cases.
This indicates that it can be treated as a well-defined internal time for these
models. Moreover we perform preliminary studies of the scalar field
perturbations with this potential. We indicate that non-Gaussian features are
present admitting for the possible observational constraints of the model.
|
[
{
"created": "Mon, 15 Sep 2008 09:45:41 GMT",
"version": "v1"
},
{
"created": "Sun, 12 Oct 2008 21:10:29 GMT",
"version": "v2"
},
{
"created": "Thu, 30 Apr 2009 01:50:22 GMT",
"version": "v3"
}
] |
2011-03-28
|
[
[
"Mielczarek",
"Jakub",
""
]
] |
The scalar field can behave like a fluid with equation of state $p_{\phi}=w\rho_{\phi}$, where $w \in [-1,1]$. In this Letter we derive a class of the scalar field potentials for which $w=$ const. Scalar field with such a potential can mimic ordinary matter, radiation, cosmic strings, etc. We perform our calculations in the framework of the loop cosmology with holonomy corrections. We solve the model analytically for the whole parameter space. Subsequently, we perform similar consideration for the model with a phantom field ($w<-1$). We show that scalar field is monotonic function in both cases. This indicates that it can be treated as a well-defined internal time for these models. Moreover we perform preliminary studies of the scalar field perturbations with this potential. We indicate that non-Gaussian features are present admitting for the possible observational constraints of the model.
|
gr-qc/0103084
|
Hans-Jurgen Matschull
|
Hans-Juergen Matschull
|
The Phase Space Structure of Multi Particle Models in 2+1 Gravity
|
72 pages, LeTeX2e, 10 eps figures
|
Class.Quant.Grav.18:3497-3560,2001
|
10.1088/0264-9381/18/17/309
|
MZ-TH/00-44
|
gr-qc
| null |
What can we learn about quantum gravity from a simple toy model, without
actually quantizing it? The toy model consists of a finite number of point
particles, coupled to three dimensional Einstein gravity. It has finitely many
physical degrees of freedom. These are basically the relative positions of the
particles in spacetime and the conjugate momenta. The resulting reduced phase
space is derived from Einstein gravity as a topological field theory. The
crucial point is thereby that we do not make any a priori assumptions about
this phase space, except that the dynamics of the gravitational field is
defined by the Einstein Hilbert action. This already leads to some interesting
features of the reduced phase space, such as a non-commutative structure of
spacetime when the model is quantized.
|
[
{
"created": "Fri, 23 Mar 2001 02:49:41 GMT",
"version": "v1"
}
] |
2014-11-17
|
[
[
"Matschull",
"Hans-Juergen",
""
]
] |
What can we learn about quantum gravity from a simple toy model, without actually quantizing it? The toy model consists of a finite number of point particles, coupled to three dimensional Einstein gravity. It has finitely many physical degrees of freedom. These are basically the relative positions of the particles in spacetime and the conjugate momenta. The resulting reduced phase space is derived from Einstein gravity as a topological field theory. The crucial point is thereby that we do not make any a priori assumptions about this phase space, except that the dynamics of the gravitational field is defined by the Einstein Hilbert action. This already leads to some interesting features of the reduced phase space, such as a non-commutative structure of spacetime when the model is quantized.
|
2103.03119
|
Benrong Mu
|
Jing Liang, Wei Lin and Benrong Mu
|
Joule-Thomson expansion of the torus-like black hole
|
14 pages, 15 figures
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, we study Joule-Thomson effects for the torus-like black hole.
The Joule-Thomson coefficients, the inversion curves and the isenthalpic curves
are studied. Furthermore, we investigate similarities and differences between
the Van der Waals fluid, the torus-like black hole and the charged AdS black
holes for the expansion. The isenthalpic curves in the $T-P$ plane are
obtained. Moreover, we determine the cooling-heating regions.
|
[
{
"created": "Thu, 4 Mar 2021 15:45:56 GMT",
"version": "v1"
}
] |
2021-03-05
|
[
[
"Liang",
"Jing",
""
],
[
"Lin",
"Wei",
""
],
[
"Mu",
"Benrong",
""
]
] |
In this paper, we study Joule-Thomson effects for the torus-like black hole. The Joule-Thomson coefficients, the inversion curves and the isenthalpic curves are studied. Furthermore, we investigate similarities and differences between the Van der Waals fluid, the torus-like black hole and the charged AdS black holes for the expansion. The isenthalpic curves in the $T-P$ plane are obtained. Moreover, we determine the cooling-heating regions.
|
1701.01983
|
Sharmanthie Fernando
|
Sharmanthie Fernando and Amanda Manning
|
Electromagnetic perturbations of a de Sitter black hole in massive
gravity
|
25 pages, and 19 figures. Submitted to International Journal of
Modern Physics D
|
International Journal of Modern Physics D 26, no:10, 1750100
(2017)
|
10.1142/S0218271817501000
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The main purpose of this paper is to study quasinormal modes (QNM) of a black
hole in massive gravity with a positive cosmological constant due to
electromagnetic perturbations. A detailed study of the QNM frequencies for the
electromagnetic field is done by varying the parameters of the theory such as
the mass, scalar charge, cosmological constant, and the spherical harmonic
index. We have employed the sixth order WKB approximation to calculate the QNM
frequencies. The electromagnetic potential for the near extreme massive gravity
de Sitter black hole is approximated with the P$\ddot{o}$schl-Teller potential
to obtain exact frequencies. Our results show that the black hole is stable
under electromagnetic perturbations. The null geodesics of the black hole in
massive gravity is employed to describe the absorption cross sections at
high-frequency limit.
|
[
{
"created": "Sun, 8 Jan 2017 16:56:50 GMT",
"version": "v1"
},
{
"created": "Mon, 30 Jan 2017 16:38:40 GMT",
"version": "v2"
}
] |
2018-07-31
|
[
[
"Fernando",
"Sharmanthie",
""
],
[
"Manning",
"Amanda",
""
]
] |
The main purpose of this paper is to study quasinormal modes (QNM) of a black hole in massive gravity with a positive cosmological constant due to electromagnetic perturbations. A detailed study of the QNM frequencies for the electromagnetic field is done by varying the parameters of the theory such as the mass, scalar charge, cosmological constant, and the spherical harmonic index. We have employed the sixth order WKB approximation to calculate the QNM frequencies. The electromagnetic potential for the near extreme massive gravity de Sitter black hole is approximated with the P$\ddot{o}$schl-Teller potential to obtain exact frequencies. Our results show that the black hole is stable under electromagnetic perturbations. The null geodesics of the black hole in massive gravity is employed to describe the absorption cross sections at high-frequency limit.
|
0806.4183
|
Eyo Ita III
|
Eyo Eyo Ita III
|
Instanton representation of Plebanski gravity XXII. Minisuperspace
quantization of gravity coupled to spin 1/2 fermionic fields
|
21 pages
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper we carry out a quantization of gravity coupled to massless spin
1/2 fermions through the instanton representation of Plebanski gravity. We have
constructed a Hilbert space of states for this model, and we have computed the
Hamilton's equations of motion. The classical equations appear, at a
superficial level, to be consistent with the quantum dynamics of the theory.
|
[
{
"created": "Wed, 25 Jun 2008 19:55:08 GMT",
"version": "v1"
},
{
"created": "Thu, 26 Jun 2008 11:39:35 GMT",
"version": "v2"
},
{
"created": "Tue, 1 Dec 2009 16:20:37 GMT",
"version": "v3"
},
{
"created": "Mon, 12 Jul 2010 10:16:49 GMT",
"version": "v4"
}
] |
2010-07-13
|
[
[
"Ita",
"Eyo Eyo",
"III"
]
] |
In this paper we carry out a quantization of gravity coupled to massless spin 1/2 fermions through the instanton representation of Plebanski gravity. We have constructed a Hilbert space of states for this model, and we have computed the Hamilton's equations of motion. The classical equations appear, at a superficial level, to be consistent with the quantum dynamics of the theory.
|
2003.07092
|
Karim Mosani
|
Karim Mosani, Dipanjan Dey, Pankaj S. Joshi
|
Global visibility of a strong curvature singularity in nonmarginally
bound dust collapse
| null |
Phys. Rev. D 102, 044037 (2020)
|
10.1103/PhysRevD.102.044037
| null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
We investigate here the local versus global visibility of a space-time
singularity formed due to the gravitational collapse of a spherically symmetric
dust cloud having a non-zero velocity function. The conditions are investigated
that ensure the global visibility of the singularity, in the sense that the
outgoing null geodesics leave the boundary of the matter cloud in the future,
whereas, in the past, these terminate at the singularity. Explicit examples of
this effect are constructed. We require that this must be a strong curvature
singularity in the sense of Tipler, to ensure the physical significance of the
scenario considered. This may act as a counterexample to the weak cosmic
censorship hypothesis.
|
[
{
"created": "Mon, 16 Mar 2020 10:07:22 GMT",
"version": "v1"
},
{
"created": "Sat, 22 Aug 2020 12:06:32 GMT",
"version": "v2"
}
] |
2020-08-26
|
[
[
"Mosani",
"Karim",
""
],
[
"Dey",
"Dipanjan",
""
],
[
"Joshi",
"Pankaj S.",
""
]
] |
We investigate here the local versus global visibility of a space-time singularity formed due to the gravitational collapse of a spherically symmetric dust cloud having a non-zero velocity function. The conditions are investigated that ensure the global visibility of the singularity, in the sense that the outgoing null geodesics leave the boundary of the matter cloud in the future, whereas, in the past, these terminate at the singularity. Explicit examples of this effect are constructed. We require that this must be a strong curvature singularity in the sense of Tipler, to ensure the physical significance of the scenario considered. This may act as a counterexample to the weak cosmic censorship hypothesis.
|
gr-qc/9406022
|
P. Suntharothok-Priesmeyer
|
Clifford M. Will
|
Testing Scalar-Tensor Gravity with Gravitational-Wave Observations of
Inspiralling Compact Binaries
|
10 pages, (3 figures upon request), WUGRAV-94-6
|
Phys.Rev. D50 (1994) 6058-6067
|
10.1103/PhysRevD.50.6058
| null |
gr-qc
| null |
Observations of gravitational waves from inspiralling compact binaries using
laser-interferometric detectors can provide accurate measures of parameters of
the source. They can also constrain alternative gravitation theories. We
analyse inspiralling compact %binaries in the context of the scalar-tensor
theory of Jordan, Fierz, Brans and Dicke, focussing on the effect on the
inspiral of energy lost to dipole gravitational radiation, whose source is the
gravitational self-binding energy of the inspiralling bodies. Using a
matched-filter analysis we obtain a bound on the coupling constant $\omega_{\rm
BD}$ of Brans-Dicke theory. For a neutron-star/black-hole binary, we find that
the bound could exceed the current bound of $\omega_{\rm BD}>500$ from
solar-system experiments, for sufficiently low-mass systems. For a $0.7
M_\odot$ neutron star and a $3 M_\odot$ black hole we find that a bound
$\omega_{\rm BD} \approx 2000$ is achievable. The bound decreases with
increasing black-hole mass. For binaries consisting of two neutron stars, the
bound is less than 500 unless the stars' masses differ by more than about $0.5
M_\odot$. For two black holes, the behavior of the inspiralling binary is
observationally indistinguishable from its behavior in general relativity.
These bounds assume reasonable neutron-star equations of state and a detector
signal-to-noise ratio of 10.
|
[
{
"created": "Wed, 15 Jun 1994 12:43:49 GMT",
"version": "v1"
}
] |
2009-10-22
|
[
[
"Will",
"Clifford M.",
""
]
] |
Observations of gravitational waves from inspiralling compact binaries using laser-interferometric detectors can provide accurate measures of parameters of the source. They can also constrain alternative gravitation theories. We analyse inspiralling compact %binaries in the context of the scalar-tensor theory of Jordan, Fierz, Brans and Dicke, focussing on the effect on the inspiral of energy lost to dipole gravitational radiation, whose source is the gravitational self-binding energy of the inspiralling bodies. Using a matched-filter analysis we obtain a bound on the coupling constant $\omega_{\rm BD}$ of Brans-Dicke theory. For a neutron-star/black-hole binary, we find that the bound could exceed the current bound of $\omega_{\rm BD}>500$ from solar-system experiments, for sufficiently low-mass systems. For a $0.7 M_\odot$ neutron star and a $3 M_\odot$ black hole we find that a bound $\omega_{\rm BD} \approx 2000$ is achievable. The bound decreases with increasing black-hole mass. For binaries consisting of two neutron stars, the bound is less than 500 unless the stars' masses differ by more than about $0.5 M_\odot$. For two black holes, the behavior of the inspiralling binary is observationally indistinguishable from its behavior in general relativity. These bounds assume reasonable neutron-star equations of state and a detector signal-to-noise ratio of 10.
|
2203.12124
|
Yen-Kheng Lim PhD
|
Ziou Yang and Yen-Kheng Lim
|
Structure of test magnetic fields and charged particle motion around the
Hayward spacetime
|
32 pages, 12 figures. Sec. 2 expanded, typos corrected
|
Phys. Rev. D 105, 124045 (2022)
|
10.1103/PhysRevD.105.124045
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A configuration of a test magnetic field in Hayward spacetime is obtained by
solving Maxwell's equation with the Hayward metric as the background. The
magnetic field lines show a dipole loop-like configuration in the regular
Hayward interior, and tends to an asymptotically uniform structure away from
the cylindrical axis. The motion of charged particles is then studied in this
spacetime. The parameters and stability of circular orbits on the equatorial
plane are studied. Aspects of non-equatorial motion are also studied.
|
[
{
"created": "Wed, 23 Mar 2022 01:35:41 GMT",
"version": "v1"
},
{
"created": "Thu, 23 Jun 2022 01:26:53 GMT",
"version": "v2"
}
] |
2022-06-24
|
[
[
"Yang",
"Ziou",
""
],
[
"Lim",
"Yen-Kheng",
""
]
] |
A configuration of a test magnetic field in Hayward spacetime is obtained by solving Maxwell's equation with the Hayward metric as the background. The magnetic field lines show a dipole loop-like configuration in the regular Hayward interior, and tends to an asymptotically uniform structure away from the cylindrical axis. The motion of charged particles is then studied in this spacetime. The parameters and stability of circular orbits on the equatorial plane are studied. Aspects of non-equatorial motion are also studied.
|
2205.08320
|
Pisin Chen
|
Pisin Chen, Misao Sasaki, Dong-han Yeom, Junggi Yoon
|
Resolving information loss paradox with Euclidean path integral
|
12 pages, 3 figures
| null |
10.1142/S0218271822420019
| null |
gr-qc hep-th
|
http://creativecommons.org/licenses/by/4.0/
|
The information loss paradox remains unresolved ever since Hawking's seminal
discovery of black hole evaporation. In this essay, we revisit the entanglement
entropy via Euclidean path integral (EPI) and allow for the branching of
semi-classical histories during the Lorentzian evolution. We posit that there
exist two histories that contribute to EPI, where one is information-losing
that dominates at early times, while the other is information-preserving that
dominates at late times. By so doing we recover the Page curve and preserve the
unitarity, albeit with the Page time shifted significantly towards the late
time. One implication is that the entropy bound may thus be violated. We
compare our approach with string-based islands and replica wormholes concepts.
|
[
{
"created": "Tue, 17 May 2022 13:15:37 GMT",
"version": "v1"
}
] |
2022-09-16
|
[
[
"Chen",
"Pisin",
""
],
[
"Sasaki",
"Misao",
""
],
[
"Yeom",
"Dong-han",
""
],
[
"Yoon",
"Junggi",
""
]
] |
The information loss paradox remains unresolved ever since Hawking's seminal discovery of black hole evaporation. In this essay, we revisit the entanglement entropy via Euclidean path integral (EPI) and allow for the branching of semi-classical histories during the Lorentzian evolution. We posit that there exist two histories that contribute to EPI, where one is information-losing that dominates at early times, while the other is information-preserving that dominates at late times. By so doing we recover the Page curve and preserve the unitarity, albeit with the Page time shifted significantly towards the late time. One implication is that the entropy bound may thus be violated. We compare our approach with string-based islands and replica wormholes concepts.
|
2301.00156
|
Spiros Cotsakis
|
Spiros Cotsakis and John Miritzis
|
Trans-Planckian censorship and spacetime singularities
|
v2: 11 pages, minor corrections, added references, matches published
version
|
Mathematics 11 (2023) 633
| null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study the effects of trans-planckian censorship conjecture (TCC) bounds on
geodesic completeness of spacetime and the associated existence for an infinite
proper time. Using Gronwall's lemma, TCC bounds can be derived directly,
leading to a result about the absence of blowup solutions. We show that the TCC
provides part of the required criteria for geodesic completeness, and we then
provide the remaining ones - the norm of the extrinsic curvature being bounded
away from zero. We also discuss the importance of these results for the
classical evolution of Friedmann universes under the assumptions of global and
regular hyperbolicity.
|
[
{
"created": "Sat, 31 Dec 2022 08:52:47 GMT",
"version": "v1"
},
{
"created": "Wed, 25 Jan 2023 10:19:55 GMT",
"version": "v2"
}
] |
2023-06-13
|
[
[
"Cotsakis",
"Spiros",
""
],
[
"Miritzis",
"John",
""
]
] |
We study the effects of trans-planckian censorship conjecture (TCC) bounds on geodesic completeness of spacetime and the associated existence for an infinite proper time. Using Gronwall's lemma, TCC bounds can be derived directly, leading to a result about the absence of blowup solutions. We show that the TCC provides part of the required criteria for geodesic completeness, and we then provide the remaining ones - the norm of the extrinsic curvature being bounded away from zero. We also discuss the importance of these results for the classical evolution of Friedmann universes under the assumptions of global and regular hyperbolicity.
|
gr-qc/0611063
|
Tao Mei
|
T. Mei
|
A New Variable in General Relativity and Its Applications for Classic
and Quantum Gravity
|
28 pages, no figure
| null | null | null |
gr-qc
| null |
A new variable in the Riemannian geometry is introduced by the tetrad and the
Ricci's coefficients of rotation, the characters of curve of the Riemannian
geometry are determined completely by the new variable; for general relativity,
all the Einstein-Hilbert action, the Einstein equation in general relativity
and the Dirac equation in curved spacetime can be expressed by the new
variable, and, further, as well the action of the theory on the interaction of
gravitational, electromagnetic and spinor field (TGESF). All the characters of
transformations of the new variable, the Einstein-Hilbert action and the action
of TGESF under the general coordinate transformations and the local Lorentz
transformations are discussed, respectively. After presenting the method of
introduction of gravitational field in terms of the principle of gauge
invariance based on the Dirac equation, and the ten constraint conditions for
the tetrad are given, the vacuum-vacuum transition amplitude with the
Faddeev-Popov ghost and the terms of external sources of the pure gravitational
field is presented; finally, as well that of TGESF.
|
[
{
"created": "Sat, 11 Nov 2006 19:35:11 GMT",
"version": "v1"
},
{
"created": "Tue, 14 Nov 2006 09:17:26 GMT",
"version": "v2"
},
{
"created": "Tue, 21 Nov 2006 09:16:01 GMT",
"version": "v3"
},
{
"created": "Thu, 7 Dec 2006 06:16:38 GMT",
"version": "v4"
}
] |
2007-05-23
|
[
[
"Mei",
"T.",
""
]
] |
A new variable in the Riemannian geometry is introduced by the tetrad and the Ricci's coefficients of rotation, the characters of curve of the Riemannian geometry are determined completely by the new variable; for general relativity, all the Einstein-Hilbert action, the Einstein equation in general relativity and the Dirac equation in curved spacetime can be expressed by the new variable, and, further, as well the action of the theory on the interaction of gravitational, electromagnetic and spinor field (TGESF). All the characters of transformations of the new variable, the Einstein-Hilbert action and the action of TGESF under the general coordinate transformations and the local Lorentz transformations are discussed, respectively. After presenting the method of introduction of gravitational field in terms of the principle of gauge invariance based on the Dirac equation, and the ten constraint conditions for the tetrad are given, the vacuum-vacuum transition amplitude with the Faddeev-Popov ghost and the terms of external sources of the pure gravitational field is presented; finally, as well that of TGESF.
|
0705.2478
|
Yong-Wan Kim
|
Yun Soo Myung, Yong-Wan Kim, and Young-Jai Park
|
Entropy of an extremal regular black hole
|
17 Pages, 4 figures, version to appear in Phys. Lett. B
|
Phys.Lett.B659:832-838,2008
|
10.1016/j.physletb.2007.12.007
| null |
gr-qc hep-th
| null |
We introduce a magnetically charged extremal regular black hole in the
coupled system of Einstein gravity and nonlinear electrodynamics. Its near
horizon geometry is given by $AdS_2\times S^2$. It turns out that the entropy
function approach does not automatically lead to a correct entropy of the
Bekenstein-Hawking entropy. This contrasts to the case of the extremal
Reissner-Norstr\"om black hole in the Einstein-Maxwell theory. We conclude that
the entropy function approach does not work for a magnetically charged extremal
regular black hole without singularity, because of the nonlinearity of the
entropy function.
|
[
{
"created": "Thu, 17 May 2007 05:38:08 GMT",
"version": "v1"
},
{
"created": "Mon, 10 Dec 2007 03:13:11 GMT",
"version": "v2"
}
] |
2008-11-26
|
[
[
"Myung",
"Yun Soo",
""
],
[
"Kim",
"Yong-Wan",
""
],
[
"Park",
"Young-Jai",
""
]
] |
We introduce a magnetically charged extremal regular black hole in the coupled system of Einstein gravity and nonlinear electrodynamics. Its near horizon geometry is given by $AdS_2\times S^2$. It turns out that the entropy function approach does not automatically lead to a correct entropy of the Bekenstein-Hawking entropy. This contrasts to the case of the extremal Reissner-Norstr\"om black hole in the Einstein-Maxwell theory. We conclude that the entropy function approach does not work for a magnetically charged extremal regular black hole without singularity, because of the nonlinearity of the entropy function.
|
gr-qc/0202001
|
Juan A. Valiente-Kroon
|
Juan A. Valiente Kroon
|
Polyhomogeneous expansions close to null and spatial infinity
|
24 pages, 5 figures. To appear in: The Conformal Structure of
Spacetimes. Geometry, Analysis, Numerics. J. Frauendiner and H. Friedrich
eds. Springer
|
Lect.Notes Phys. 604 (2002) 135-160
| null | null |
gr-qc
| null |
A study of the linearised gravitational field (spin 2 zero-rest-mass field)
on a Minkowski background close to spatial infinity is done. To this purpose, a
certain representation of spatial infinity in which it is depicted as a
cylinder is used. A first analysis shows that the solutions generically develop
a particular type of logarithmic divergence at the sets where spatial infinity
touches null infinity. A regularity condition on the initial data can be
deduced from the analysis of some transport equations on the cylinder at
spatial infinity. It is given in terms of the linearised version of the Cotton
tensor and symmetrised higher order derivatives, and it ensures that the
solutions of the transport equations extend analytically to the sets where
spatial infinity touches null infinity. It is later shown that this regularity
condition together with the requirement of some particular degree of tangential
smoothness ensures logarithm-free expansions of the time development of the
linearised gravitational field close to spatial and null infinities.
|
[
{
"created": "Fri, 1 Feb 2002 09:53:30 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Kroon",
"Juan A. Valiente",
""
]
] |
A study of the linearised gravitational field (spin 2 zero-rest-mass field) on a Minkowski background close to spatial infinity is done. To this purpose, a certain representation of spatial infinity in which it is depicted as a cylinder is used. A first analysis shows that the solutions generically develop a particular type of logarithmic divergence at the sets where spatial infinity touches null infinity. A regularity condition on the initial data can be deduced from the analysis of some transport equations on the cylinder at spatial infinity. It is given in terms of the linearised version of the Cotton tensor and symmetrised higher order derivatives, and it ensures that the solutions of the transport equations extend analytically to the sets where spatial infinity touches null infinity. It is later shown that this regularity condition together with the requirement of some particular degree of tangential smoothness ensures logarithm-free expansions of the time development of the linearised gravitational field close to spatial and null infinities.
|
1802.00860
|
H\'ector Ra\'ul Olivares S\'anchez
|
Hector Olivares, Oliver Porth, Yosuke Mizuno
|
The Black Hole Accretion Code: adaptive mesh refinement and constrained
transport
|
10 pages, 5 figures, submitted to the Proceedings of the 12th
International Conference on Numerical Modeling of Space Plasma Flows
(ASTRONUM-2017)
| null |
10.1088/1742-6596/1031/1/012008
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
With the forthcoming VLBI images of Sgr A* and M87, simulations of accretion
flows onto black holes acquire a special importance to aid with the
interpretation of the observations and to test the predictions of different
accretion scenarios, including those coming from alternative theories of
gravity. The Black Hole Accretion Code (BHAC) is a new multidimensional
general-relativistic magnetohydrondynamics (GRMHD) module for the MPI-AMRVAC
framework. It exploits its adaptive mesh refinement techniques (AMR) to solve
the equations of ideal magnetohydrodynamics in arbitrary curved spacetimes with
a significant speedup and saving in computational cost. In a previous work,
this was shown using a Generalized Lagrange Multiplier (GLM) to enforce the
solenoidal constraint of the magnetic field. While GLM is fully compatible with
MPI-AMRVAC's AMR infrastructure, we found that simulations were sensible to the
divergence control technique employed, resulting in an improved behavior for
those using Constrained Transport (CT). However, cell-centered CT is
incompatible with AMR, and several modifications were required to make AMR
compatible with staggered CT. We present here preliminary results of these new
additions, which achieved machine precision fulfillment of the solenoidal
constraint and a significant speedup in a problem close to the intended
scientific application.
|
[
{
"created": "Fri, 2 Feb 2018 21:44:15 GMT",
"version": "v1"
}
] |
2019-10-09
|
[
[
"Olivares",
"Hector",
""
],
[
"Porth",
"Oliver",
""
],
[
"Mizuno",
"Yosuke",
""
]
] |
With the forthcoming VLBI images of Sgr A* and M87, simulations of accretion flows onto black holes acquire a special importance to aid with the interpretation of the observations and to test the predictions of different accretion scenarios, including those coming from alternative theories of gravity. The Black Hole Accretion Code (BHAC) is a new multidimensional general-relativistic magnetohydrondynamics (GRMHD) module for the MPI-AMRVAC framework. It exploits its adaptive mesh refinement techniques (AMR) to solve the equations of ideal magnetohydrodynamics in arbitrary curved spacetimes with a significant speedup and saving in computational cost. In a previous work, this was shown using a Generalized Lagrange Multiplier (GLM) to enforce the solenoidal constraint of the magnetic field. While GLM is fully compatible with MPI-AMRVAC's AMR infrastructure, we found that simulations were sensible to the divergence control technique employed, resulting in an improved behavior for those using Constrained Transport (CT). However, cell-centered CT is incompatible with AMR, and several modifications were required to make AMR compatible with staggered CT. We present here preliminary results of these new additions, which achieved machine precision fulfillment of the solenoidal constraint and a significant speedup in a problem close to the intended scientific application.
|
1901.03387
|
Salvador Robles-Perez
|
Salvador J. Robles-Perez
|
Time reversal symmetry in cosmology and the creation of a
universe-antiuniverse pair
|
9 pages, 3 figures. Minor changes and typos corrected, some
references added and Fig. 2 has been improved
|
Universe 2019, 5(6), 150
|
10.3390/universe5060150
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The classical evolution of the universe can be seen as a parametrised
worldline of the minisuperspace, with the time variable $t$ the parameter that
parametrises the worldline. The time reversal symmetry of the field equations
implies that for any positive oriented solution there can be a symmetric
negative oriented one that, in terms of the same time variable, represent an
expanding and a contracting universe, respectively. However, the choice of the
time variable induced by the correct value of the Schr\"odinger equation in the
two universes makes that their physical time variables could be reversely
related. In that case, the two universes would be both expanding universes from
the point of view of their internal inhabitants, who identify matter with the
particles that move in their spacetimes and antimatter with the particles that
move in the time reversely symmetric universe. If the assumptions considered
are consistent with a realistic scenario of our universe, the creation of a
universe-antiuniverse pair might explain two main and related problems in
cosmology: the time asymmetry and the primordial matter-antimatter asymmetry of
our universe.
|
[
{
"created": "Thu, 3 Jan 2019 07:14:53 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Oct 2019 10:44:38 GMT",
"version": "v2"
},
{
"created": "Wed, 16 Oct 2019 07:27:00 GMT",
"version": "v3"
}
] |
2019-10-17
|
[
[
"Robles-Perez",
"Salvador J.",
""
]
] |
The classical evolution of the universe can be seen as a parametrised worldline of the minisuperspace, with the time variable $t$ the parameter that parametrises the worldline. The time reversal symmetry of the field equations implies that for any positive oriented solution there can be a symmetric negative oriented one that, in terms of the same time variable, represent an expanding and a contracting universe, respectively. However, the choice of the time variable induced by the correct value of the Schr\"odinger equation in the two universes makes that their physical time variables could be reversely related. In that case, the two universes would be both expanding universes from the point of view of their internal inhabitants, who identify matter with the particles that move in their spacetimes and antimatter with the particles that move in the time reversely symmetric universe. If the assumptions considered are consistent with a realistic scenario of our universe, the creation of a universe-antiuniverse pair might explain two main and related problems in cosmology: the time asymmetry and the primordial matter-antimatter asymmetry of our universe.
|
2108.06523
|
Haryanto Siahaan
|
Haryanto M. Siahaan and Paulus C. Tjiang
|
Destroying Kaluza-Klein and Kerr-Newman black holes
|
17 pages, 9 figures
| null | null | null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
We investigate the destroying of charged and rotating black holes in
Einstein-Maxwell-(dilaton) theory. We show that a test particle with some
appropriate properties in the black hole background can turn the black hole
into a naked singularity. In this work, we neglect the self-force, self-energy,
and radiative effects as considered by some others in literature. As the
result, we are able to show that the Kerr-Newman and Kaluza-Klein black holes
can be destroyed by the test particle. Furthermore, for Kaluza-Klein black
hole, we consider the overspinning of the black hole by a neutral test scalar
field.
|
[
{
"created": "Sat, 14 Aug 2021 12:23:11 GMT",
"version": "v1"
}
] |
2021-08-17
|
[
[
"Siahaan",
"Haryanto M.",
""
],
[
"Tjiang",
"Paulus C.",
""
]
] |
We investigate the destroying of charged and rotating black holes in Einstein-Maxwell-(dilaton) theory. We show that a test particle with some appropriate properties in the black hole background can turn the black hole into a naked singularity. In this work, we neglect the self-force, self-energy, and radiative effects as considered by some others in literature. As the result, we are able to show that the Kerr-Newman and Kaluza-Klein black holes can be destroyed by the test particle. Furthermore, for Kaluza-Klein black hole, we consider the overspinning of the black hole by a neutral test scalar field.
|
0711.4620
|
Jose M. Martin-Garcia
|
Carsten Gundlach, Jose M. Martin-Garcia
|
Critical phenomena in gravitational collapse
|
51 pages, 5 figures. Major update of Living Rev. Rel. 2 (1999) 4
|
LivingRev.Rel.10:5,2007
|
10.12942/lrr-2007-5
| null |
gr-qc
| null |
As first discovered by Choptuik, the black hole threshold in the space of
initial data for general relativity shows both surprising structure and
surprising simplicity. Universality, power-law scaling of the black hole mass,
and scale echoing have given rise to the term "critical phenomena". They are
explained by the existence of exact solutions which are attractors within the
black hole threshold, that is, attractors of codimension one in phase space,
and which are typically self-similar. Critical phenomena give a natural route
from smooth initial data to arbitrarily large curvatures visible from infinity,
and are therefore likely to be relevant for cosmic censorship, quantum gravity,
astrophysics, and our general understanding of the dynamics of general
relativity.
|
[
{
"created": "Wed, 28 Nov 2007 23:27:15 GMT",
"version": "v1"
}
] |
2015-05-13
|
[
[
"Gundlach",
"Carsten",
""
],
[
"Martin-Garcia",
"Jose M.",
""
]
] |
As first discovered by Choptuik, the black hole threshold in the space of initial data for general relativity shows both surprising structure and surprising simplicity. Universality, power-law scaling of the black hole mass, and scale echoing have given rise to the term "critical phenomena". They are explained by the existence of exact solutions which are attractors within the black hole threshold, that is, attractors of codimension one in phase space, and which are typically self-similar. Critical phenomena give a natural route from smooth initial data to arbitrarily large curvatures visible from infinity, and are therefore likely to be relevant for cosmic censorship, quantum gravity, astrophysics, and our general understanding of the dynamics of general relativity.
|
1603.08600
|
Baocheng Zhang
|
Baocheng Zhang
|
The mass formula for an exotic BTZ black hole
| null |
Annals of Physics 367 (2016) 280-287
|
10.1016/j.aop.2016.01.021
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
An exotic Banados-Teitelboim-Zanelli (BTZ) black hole has an angular momentum
larger than its mass in three dimension (3D), which suggests the possibility
that cosmic censorship could be violated if angular momentum is extracted by
the Penrose process. In this paper, we propose a mass formula for the exotic
BTZ black hole and show no violation of weak cosmic censorship in the gedanken
process above by understanding properly its mass formula. Unlike the other
black holes, the total energy of the exotic BTZ black hole is represented by
the angular momentum instead of the mass, which supports a basic point of view
that the same geometry should be determined by the same energy in 3D general
relativity whose equation of motion can be given either by normal 3D Einstein
gravity or by exotic 3D Einstein gravity. However, only the mass of the exotic
black hole is related to the thermodynamics and other forms of energy are
"dumb", which is consistent with the earlier thermodynamic analysis about
exotic black holes.
|
[
{
"created": "Tue, 29 Mar 2016 00:51:07 GMT",
"version": "v1"
}
] |
2016-03-30
|
[
[
"Zhang",
"Baocheng",
""
]
] |
An exotic Banados-Teitelboim-Zanelli (BTZ) black hole has an angular momentum larger than its mass in three dimension (3D), which suggests the possibility that cosmic censorship could be violated if angular momentum is extracted by the Penrose process. In this paper, we propose a mass formula for the exotic BTZ black hole and show no violation of weak cosmic censorship in the gedanken process above by understanding properly its mass formula. Unlike the other black holes, the total energy of the exotic BTZ black hole is represented by the angular momentum instead of the mass, which supports a basic point of view that the same geometry should be determined by the same energy in 3D general relativity whose equation of motion can be given either by normal 3D Einstein gravity or by exotic 3D Einstein gravity. However, only the mass of the exotic black hole is related to the thermodynamics and other forms of energy are "dumb", which is consistent with the earlier thermodynamic analysis about exotic black holes.
|
1105.3607
|
Mariusz Dabrowski P.
|
Mariusz P. Dabrowski
|
Spacetime averaging of exotic singularity universes
|
5 pages, no figures, REVTEX4-1, minor improvements
|
Phys.Lett.B702:320-323,2011
|
10.1016/j.physletb.2011.07.043
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Taking a spacetime average as a measure of the strength of singularities we
show that big-rips (type I) are stronger than big-bangs. The former have
infinite spacetime averages while the latter have them equal to zero. The
sudden future singularities (type II) and $w-$singularities (type V) have
finite spacetime averages. The finite scale factor (type III) singularities for
some values of the parameters may have an infinite average and in that sense
they may be considered stronger than big-bangs.
|
[
{
"created": "Wed, 18 May 2011 12:38:43 GMT",
"version": "v1"
},
{
"created": "Fri, 27 May 2011 05:52:59 GMT",
"version": "v2"
}
] |
2011-09-28
|
[
[
"Dabrowski",
"Mariusz P.",
""
]
] |
Taking a spacetime average as a measure of the strength of singularities we show that big-rips (type I) are stronger than big-bangs. The former have infinite spacetime averages while the latter have them equal to zero. The sudden future singularities (type II) and $w-$singularities (type V) have finite spacetime averages. The finite scale factor (type III) singularities for some values of the parameters may have an infinite average and in that sense they may be considered stronger than big-bangs.
|
1203.6084
|
Mahouton J. Stephane Houndjo Dr
|
M. J. S. Houndjo, C. E. M. Batista, J. P. Campos, O. F. Piattella
|
Finite-time singularities in f(R, T) gravity and the effect of conformal
anomaly
|
18 pages; Accepted for publication in Canadian Journal of Physics
(CJP)
|
Can. J. Phys. 91(7), 548-553 (2013)
|
10.1139/cjp-2013-0023
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We investigate $f(R,T)$ gravity models ($R$ is the curvature scalar and $T$
is the trace of the stress-energy tensor of ordinary matter) that are able to
reproduce the four known types of future finite-time singularities. We choose a
suitable expression for the Hubble parameter in order to realise the cosmic
acceleration and we introduce two parameters, $\alpha$ and $H_s$, which
characterise each type of singularity. We address conformal anomaly and we
observe that it cannot remove the sudden singularity or the type IV one, but,
for some values of $\alpha$, the big rip and the type III singularity may be
avoided. We also find that, even without taking into account conformal anomaly,
the big rip and the type III singularity may be removed thanks to the presence
of the $T$ contribution of the $f(R,T)$ theory.
|
[
{
"created": "Tue, 27 Mar 2012 20:33:01 GMT",
"version": "v1"
},
{
"created": "Sun, 24 Mar 2013 11:35:23 GMT",
"version": "v2"
}
] |
2013-08-06
|
[
[
"Houndjo",
"M. J. S.",
""
],
[
"Batista",
"C. E. M.",
""
],
[
"Campos",
"J. P.",
""
],
[
"Piattella",
"O. F.",
""
]
] |
We investigate $f(R,T)$ gravity models ($R$ is the curvature scalar and $T$ is the trace of the stress-energy tensor of ordinary matter) that are able to reproduce the four known types of future finite-time singularities. We choose a suitable expression for the Hubble parameter in order to realise the cosmic acceleration and we introduce two parameters, $\alpha$ and $H_s$, which characterise each type of singularity. We address conformal anomaly and we observe that it cannot remove the sudden singularity or the type IV one, but, for some values of $\alpha$, the big rip and the type III singularity may be avoided. We also find that, even without taking into account conformal anomaly, the big rip and the type III singularity may be removed thanks to the presence of the $T$ contribution of the $f(R,T)$ theory.
|
1812.02758
|
Giuseppe Ficarra
|
Giuseppe Ficarra, Paolo Pani and Helvi Witek
|
Impact of multiple modes on the black-hole superradiant instability
|
21 pages, 12 figures; matches version accepted in PRD
|
Phys. Rev. D 99, 104019 (2019)
|
10.1103/PhysRevD.99.104019
| null |
gr-qc astro-ph.HE hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Ultralight bosonic fields in the mass range $\sim (10^{-20}-10^{-11})\,{\rm
eV}$ can trigger a superradiant instability that extracts energy and angular
momentum from an astrophysical black hole with mass $M\sim(5,10^{10})M_\odot$,
forming a nonspherical, rotating condensate around it. So far, most studies of
the evolution and end-state of the instability have been limited to initial
data containing only the fastest growing superradiant mode. By studying the
evolution of multimode data in a quasi-adiabatic approximation, we show that
the dynamics is much richer and depend strongly on the energy of the seed, on
the relative amplitude between modes, and on the gravitational coupling. If the
seed energy is a few percent of the black-hole mass, a black hole surrounded by
a mixture of superradiant and nonsuperradiant modes with comparable amplitudes
might not undergo a superradiant unstable phase, depending on the value of the
boson mass. If the seed energy is smaller, as in the case of an instability
triggered by quantum fluctuations, the effect of nonsuperradiant modes is
negligible. We discuss the implications of these findings for current
constraints on ultralight fields with electromagnetic and gravitational-wave
observations.
|
[
{
"created": "Thu, 6 Dec 2018 19:01:49 GMT",
"version": "v1"
},
{
"created": "Thu, 19 Sep 2019 21:42:16 GMT",
"version": "v2"
}
] |
2019-09-23
|
[
[
"Ficarra",
"Giuseppe",
""
],
[
"Pani",
"Paolo",
""
],
[
"Witek",
"Helvi",
""
]
] |
Ultralight bosonic fields in the mass range $\sim (10^{-20}-10^{-11})\,{\rm eV}$ can trigger a superradiant instability that extracts energy and angular momentum from an astrophysical black hole with mass $M\sim(5,10^{10})M_\odot$, forming a nonspherical, rotating condensate around it. So far, most studies of the evolution and end-state of the instability have been limited to initial data containing only the fastest growing superradiant mode. By studying the evolution of multimode data in a quasi-adiabatic approximation, we show that the dynamics is much richer and depend strongly on the energy of the seed, on the relative amplitude between modes, and on the gravitational coupling. If the seed energy is a few percent of the black-hole mass, a black hole surrounded by a mixture of superradiant and nonsuperradiant modes with comparable amplitudes might not undergo a superradiant unstable phase, depending on the value of the boson mass. If the seed energy is smaller, as in the case of an instability triggered by quantum fluctuations, the effect of nonsuperradiant modes is negligible. We discuss the implications of these findings for current constraints on ultralight fields with electromagnetic and gravitational-wave observations.
|
2105.04687
|
Pedro Fernandes
|
Pedro G. S. Fernandes
|
Gravity with a generalized conformal scalar field: Theory and solutions
|
7 pages, 1 ancillary file. V2: References added and typo corrected.
Published in Physical Review D
|
Phys. Rev. D 103, 104065 (2021)
|
10.1103/PhysRevD.103.104065
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We naturally extend the theory of gravity with a conformally coupled scalar
field by only requiring conformal invariance of the scalar field equation of
motion and not of the action. The classically extended theory incorporates a
scalar-Gauss-Bonnet sector and has second-order equations of motion, belonging
to the Horndeski class. Remarkably, the theory features a purely geometrical
field equation that allows for closed-form black hole solutions and cosmologies
to be easily found. These solutions permit investigations of in-vogue
scalar-Gauss-Bonnet corrections to the gravitational action without the need of
resorting to approximations or numerical methods. We discuss on the connection
to the recently formulated 4D Einstein-Gauss-Bonnet theory of gravity.
|
[
{
"created": "Mon, 10 May 2021 22:01:32 GMT",
"version": "v1"
},
{
"created": "Fri, 4 Jun 2021 14:25:54 GMT",
"version": "v2"
}
] |
2021-06-07
|
[
[
"Fernandes",
"Pedro G. S.",
""
]
] |
We naturally extend the theory of gravity with a conformally coupled scalar field by only requiring conformal invariance of the scalar field equation of motion and not of the action. The classically extended theory incorporates a scalar-Gauss-Bonnet sector and has second-order equations of motion, belonging to the Horndeski class. Remarkably, the theory features a purely geometrical field equation that allows for closed-form black hole solutions and cosmologies to be easily found. These solutions permit investigations of in-vogue scalar-Gauss-Bonnet corrections to the gravitational action without the need of resorting to approximations or numerical methods. We discuss on the connection to the recently formulated 4D Einstein-Gauss-Bonnet theory of gravity.
|
1609.06817
|
Wen-Biao Han
|
Wen-Biao Han
|
Fast Evolution and Waveform Generator for Extreme-Mass-Ratio Inspirals
in Equatorial-Circular Orbits
|
19 pages, 18 figures, 4 tables
|
Class. Quantum Grav. 33 (2016) 065009
|
10.1088/0264-9381/33/6/065009
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper we discuss the development of a fast and accurate waveform
model for the quasi-circular orbital evolution of extreme-mass-ratio-inspirals
(EMRIs). This model simply employs the data of a few numerical Teukoulsky-based
energy fluxes and waveforms to fit out a set of polynomials for the entire
fluxes and waveforms. These obtained polynomials are accurate enough in the
entire evolution domain, and much more accurate than the resummation
post-Newtonian (PN) energy fluxes and waveforms, especially when the spin of a
black hole becomes large. The dynamical equation we adopted for orbital
revolution is the effective-one-body (EOB) formalism. Because of the simplified
expressions, the efficiency of calculating the orbital evolution with our
polynomials is also better than the traditional method which uses the resummed
PN analytical fluxes. Our model should be useful in calculation of waveform
templates of EMRIs for the gravitational wave detectors such as the evolved
Laser Interferometer Space Antenna (eLISA).
|
[
{
"created": "Thu, 22 Sep 2016 04:28:36 GMT",
"version": "v1"
}
] |
2016-09-23
|
[
[
"Han",
"Wen-Biao",
""
]
] |
In this paper we discuss the development of a fast and accurate waveform model for the quasi-circular orbital evolution of extreme-mass-ratio-inspirals (EMRIs). This model simply employs the data of a few numerical Teukoulsky-based energy fluxes and waveforms to fit out a set of polynomials for the entire fluxes and waveforms. These obtained polynomials are accurate enough in the entire evolution domain, and much more accurate than the resummation post-Newtonian (PN) energy fluxes and waveforms, especially when the spin of a black hole becomes large. The dynamical equation we adopted for orbital revolution is the effective-one-body (EOB) formalism. Because of the simplified expressions, the efficiency of calculating the orbital evolution with our polynomials is also better than the traditional method which uses the resummed PN analytical fluxes. Our model should be useful in calculation of waveform templates of EMRIs for the gravitational wave detectors such as the evolved Laser Interferometer Space Antenna (eLISA).
|
2306.02423
|
Marko Stojanovic
|
Marko Stojanovic, Neven Bilic, Dragoljub D. Dimitrijevic, Goran S.
Djordjevic, Milan Milosevic
|
Tachyon constant-roll inflation in Randall-Sundrum II cosmology
| null |
IJMPA 38, 2343003 (2023)
|
10.1142/S0217751X23430030
| null |
gr-qc
|
http://creativecommons.org/licenses/by-nc-sa/4.0/
|
We study inflation in a model with constant second slow-roll parameter
$\eta$. In this case, the Hubble expansion rate equation has analytical
solutions describing four possible, nontrivial inflation scenarios. The
evolution of the inflaton governed by a tachyon field is studied in the
framework of the standard and Randall-Sundrum II cosmology. The attractor
behavior of the solution is briefly demonstrated. Finally, the calculated
values of the parameters $n_{\rm s}$ and $r$ are compared with observational
data.
|
[
{
"created": "Sun, 4 Jun 2023 17:55:05 GMT",
"version": "v1"
},
{
"created": "Thu, 22 Jun 2023 12:22:53 GMT",
"version": "v2"
}
] |
2024-07-03
|
[
[
"Stojanovic",
"Marko",
""
],
[
"Bilic",
"Neven",
""
],
[
"Dimitrijevic",
"Dragoljub D.",
""
],
[
"Djordjevic",
"Goran S.",
""
],
[
"Milosevic",
"Milan",
""
]
] |
We study inflation in a model with constant second slow-roll parameter $\eta$. In this case, the Hubble expansion rate equation has analytical solutions describing four possible, nontrivial inflation scenarios. The evolution of the inflaton governed by a tachyon field is studied in the framework of the standard and Randall-Sundrum II cosmology. The attractor behavior of the solution is briefly demonstrated. Finally, the calculated values of the parameters $n_{\rm s}$ and $r$ are compared with observational data.
|
1607.01934
|
Clemens S\"amann
|
Clemens S\"amann, Roland Steinbauer, Robert \v{S}varc
|
Completeness of general pp-wave spacetimes and their impulsive limit
|
26 pages, 3 figures
|
2016 Class. Quantum Grav. 33 215006
|
10.1088/0264-9381/33/21/215006
| null |
gr-qc math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We investigate geodesic completeness in the full family of pp-wave or
Brinkmann spacetimes in their extended as well as in their impulsive form. This
class of geometries contains the recently studied gyratonic pp-waves, modelling
the exterior field of a spinning beam of null particles, as well as NPWs, which
generalise classical pp-waves by allowing for a general wave surface. The
problem of geodesic completeness reduces to the question of completeness of
trajectories on a Riemannian manifold under an external force field. Building
upon respective recent results we derive completeness criteria in terms of the
spatial asymptotics of the profile function in the extended case. In the
impulsive case we use a fixed point argument to show that irrespective of the
behaviour of the profile function all geometries in the class are complete.
|
[
{
"created": "Thu, 7 Jul 2016 09:31:59 GMT",
"version": "v1"
},
{
"created": "Fri, 8 Jul 2016 07:24:27 GMT",
"version": "v2"
},
{
"created": "Sun, 16 Oct 2016 17:07:38 GMT",
"version": "v3"
}
] |
2016-10-18
|
[
[
"Sämann",
"Clemens",
""
],
[
"Steinbauer",
"Roland",
""
],
[
"Švarc",
"Robert",
""
]
] |
We investigate geodesic completeness in the full family of pp-wave or Brinkmann spacetimes in their extended as well as in their impulsive form. This class of geometries contains the recently studied gyratonic pp-waves, modelling the exterior field of a spinning beam of null particles, as well as NPWs, which generalise classical pp-waves by allowing for a general wave surface. The problem of geodesic completeness reduces to the question of completeness of trajectories on a Riemannian manifold under an external force field. Building upon respective recent results we derive completeness criteria in terms of the spatial asymptotics of the profile function in the extended case. In the impulsive case we use a fixed point argument to show that irrespective of the behaviour of the profile function all geometries in the class are complete.
|
gr-qc/0404058
|
Tomislav Prokopec
|
Bjorn Garbrecht, Tomislav Prokopec (Heidelberg University)
|
Unruh response functions for scalar fields in de Sitter space
|
16 pages, 1 figure, accepted for publication by Classical and Quantum
Gravity
|
Class.Quant.Grav. 21 (2004) 4993-5004
|
10.1088/0264-9381/21/21/016
|
HD-THEP-04-11
|
gr-qc astro-ph hep-th
| null |
We calculate the response functions of a freely falling Unruh detector in de
Sitter space coupled to scalar fields of different coupling to the curvature,
including the minimally coupled massless case. Although the responses differ
strongly in the infrared as a consequence of the amplification of superhorizon
modes, the energy levels of the detector are thermally populated.
|
[
{
"created": "Tue, 13 Apr 2004 11:14:48 GMT",
"version": "v1"
},
{
"created": "Sat, 9 Oct 2004 15:01:58 GMT",
"version": "v2"
}
] |
2009-11-10
|
[
[
"Garbrecht",
"Bjorn",
"",
"Heidelberg University"
],
[
"Prokopec",
"Tomislav",
"",
"Heidelberg University"
]
] |
We calculate the response functions of a freely falling Unruh detector in de Sitter space coupled to scalar fields of different coupling to the curvature, including the minimally coupled massless case. Although the responses differ strongly in the infrared as a consequence of the amplification of superhorizon modes, the energy levels of the detector are thermally populated.
|
0810.0078
|
Yun Soo Myung
|
Yun Soo Myung, Myungseok Yoon
|
Regular black hole in three dimensions
|
15 pages, 16 figures, 3D noncommutative black hole included as Sec 4,
a version to appear in EPJC
|
Eur.Phys.J.C62:405-411,2009
|
10.1140/epjc/s10052-009-1036-9
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We find a new black hole in three dimensional anti-de Sitter space by
introducing an anisotropic perfect fluid inspired by the noncommutative black
hole. This is a regular black hole with two horizons. We compare thermodynamics
of this black hole with that of non-rotating BTZ black hole. The first-law of
thermodynamics is not compatible with the Bekenstein-Hawking entropy.
|
[
{
"created": "Wed, 1 Oct 2008 06:13:42 GMT",
"version": "v1"
},
{
"created": "Thu, 9 Apr 2009 02:06:13 GMT",
"version": "v2"
}
] |
2009-07-24
|
[
[
"Myung",
"Yun Soo",
""
],
[
"Yoon",
"Myungseok",
""
]
] |
We find a new black hole in three dimensional anti-de Sitter space by introducing an anisotropic perfect fluid inspired by the noncommutative black hole. This is a regular black hole with two horizons. We compare thermodynamics of this black hole with that of non-rotating BTZ black hole. The first-law of thermodynamics is not compatible with the Bekenstein-Hawking entropy.
|
0906.2520
|
Slava G. Turyshev
|
Slava G. Turyshev
|
Testing Relativistic Gravity from Space
|
5 pages, 3 figures, invited talk at the IAU Symposium 261 "Relativity
in Fundamental Astronomy: Dynamics, Reference Frames, and Data Analysis", 27
April - 1 May 2009, Virginia Beach, VA, USA
|
in ``Relativity in Fundamental Astronomy: Dynamics, Reference
Frames, and Data Analysis'', eds. S.A. Klioner, P.K. Seidelmann, M.H.
Soffel., pp. 204-208 (Cambridge University Press, 2010)
|
10.1017/S1743921309990408
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Recent experiments have successfully tested Einstein's general theory of
relativity to remarkable precision. We discuss recent progress in the tests of
relativistic gravity in the solar system and present motivations for the new
generation of high-accuracy gravitational experiments. We especially focus on
the concepts aiming to probe parametrized-post-Newtonian parameter $\gamma$ and
evaluate the discovery potential of the recently proposed experiments.
|
[
{
"created": "Sun, 14 Jun 2009 08:37:52 GMT",
"version": "v1"
},
{
"created": "Wed, 29 Jul 2009 19:59:23 GMT",
"version": "v2"
}
] |
2015-05-13
|
[
[
"Turyshev",
"Slava G.",
""
]
] |
Recent experiments have successfully tested Einstein's general theory of relativity to remarkable precision. We discuss recent progress in the tests of relativistic gravity in the solar system and present motivations for the new generation of high-accuracy gravitational experiments. We especially focus on the concepts aiming to probe parametrized-post-Newtonian parameter $\gamma$ and evaluate the discovery potential of the recently proposed experiments.
|
1611.04545
|
Nihan Kat{\i}rc{\i}
|
Ozgur Akarsu, Metin Arik, Nihan Katirci
|
Inflation and late time acceleration designed by Stueckelberg massive
photon
|
Invited review; matches the version to appear in Foundations of
Physics; 25 pages, 1 figure
|
Found. Phys. 47 (2017) 769-796
|
10.1007/s10701-016-0059-y
| null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present a mini review of the Stueckelberg mechanism, which was proposed to
make the abelian gauge theories massive as an alternative to Higgs mechanism,
within the framework of Minkowski as well as curved spacetimes. The higher the
scale the tighter the bounds on the photon mass, which might be gained via the
Stueckelberg mechanism, may be signalling that even an extremely small mass of
the photon which cannot be measured directly could have far reaching effects in
cosmology. We present a cosmological model where Stueckelberg fields, which
consist of both scalar and vector fields, are non-minimally coupled to gravity
and the universe could go through a decelerating expansion phase sandwiched by
two different accelerated expansion phases. We discuss also the possible
anisotropic extensions of the model.
|
[
{
"created": "Mon, 14 Nov 2016 20:06:31 GMT",
"version": "v1"
},
{
"created": "Thu, 12 Jan 2017 14:07:35 GMT",
"version": "v2"
}
] |
2018-09-28
|
[
[
"Akarsu",
"Ozgur",
""
],
[
"Arik",
"Metin",
""
],
[
"Katirci",
"Nihan",
""
]
] |
We present a mini review of the Stueckelberg mechanism, which was proposed to make the abelian gauge theories massive as an alternative to Higgs mechanism, within the framework of Minkowski as well as curved spacetimes. The higher the scale the tighter the bounds on the photon mass, which might be gained via the Stueckelberg mechanism, may be signalling that even an extremely small mass of the photon which cannot be measured directly could have far reaching effects in cosmology. We present a cosmological model where Stueckelberg fields, which consist of both scalar and vector fields, are non-minimally coupled to gravity and the universe could go through a decelerating expansion phase sandwiched by two different accelerated expansion phases. We discuss also the possible anisotropic extensions of the model.
|
1501.03806
|
Emil Mottola
|
Pawel O. Mazur and Emil Mottola
|
Surface Tension and Negative Pressure Interior of a Non-Singular `Black
Hole'
|
45 pages, 10 figures, Dedicated to Professor Andrzej Staruszkiewicz
on the occasion of his 75th birthday
| null |
10.1088/0264-9381/32/21/215024
|
LA-UR-15-20030
|
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The constant density interior Schwarzschild solution for a static,
spherically symmetric collapsed star has a divergent pressure when its radius
$R\le\frac{9}{8}R_s=\frac{9}{4}GM$. We show that this divergence is integrable,
and induces a non-isotropic transverse stress with a finite redshifted surface
tension on a spherical surface of radius
$R_0=3R\sqrt{1-\frac{8}{9}\frac{R}{R_s}}$. For $r < R_0$ the interior
Schwarzschild solution exhibits negative pressure. When $R=R_s$, the surface is
localized at the Schwarzschild radius itself, $R_0=R_s$, and the solution has
constant negative pressure $p =-\bar\rho$ everywhere in the interior $r<R_s$,
thereby describing a gravitational condensate star, a fully collapsed
non-singular state already inherent in and predicted by classical General
Relativity. The redshifted surface tension of the condensate star surface is
given by $\tau_s=\Delta\kappa/8\pi G$, where
$\Delta\kappa=\kappa_+-\kappa_-=2\kappa_+=1/R_s$ is the difference of equal and
opposite surface gravities between the exterior and interior Schwarzschild
solutions. The First Law, $dM=dE_v+\tau_s dA$ is recognized as a purely
mechanical classical relation at zero temperature and zero entropy, describing
the volume energy and surface energy change respectively. Since there is no
event horizon, the Schwarzschild time t of such a non-singular gravitational
condensate star is a global time, fully consistent with unitary time evolution
in quantum theory. The $p=-\bar\rho$ interior acts as a defocusing lens for
light passing through the condensate, leading to imaging characteristics
distinguishable from a classical black hole. A further observational test of
gravitational condensate stars with a physical surface vs. black holes is the
discrete surface modes of oscillation which should be detectable by their
gravitational wave signatures.
|
[
{
"created": "Thu, 15 Jan 2015 20:47:02 GMT",
"version": "v1"
}
] |
2015-10-21
|
[
[
"Mazur",
"Pawel O.",
""
],
[
"Mottola",
"Emil",
""
]
] |
The constant density interior Schwarzschild solution for a static, spherically symmetric collapsed star has a divergent pressure when its radius $R\le\frac{9}{8}R_s=\frac{9}{4}GM$. We show that this divergence is integrable, and induces a non-isotropic transverse stress with a finite redshifted surface tension on a spherical surface of radius $R_0=3R\sqrt{1-\frac{8}{9}\frac{R}{R_s}}$. For $r < R_0$ the interior Schwarzschild solution exhibits negative pressure. When $R=R_s$, the surface is localized at the Schwarzschild radius itself, $R_0=R_s$, and the solution has constant negative pressure $p =-\bar\rho$ everywhere in the interior $r<R_s$, thereby describing a gravitational condensate star, a fully collapsed non-singular state already inherent in and predicted by classical General Relativity. The redshifted surface tension of the condensate star surface is given by $\tau_s=\Delta\kappa/8\pi G$, where $\Delta\kappa=\kappa_+-\kappa_-=2\kappa_+=1/R_s$ is the difference of equal and opposite surface gravities between the exterior and interior Schwarzschild solutions. The First Law, $dM=dE_v+\tau_s dA$ is recognized as a purely mechanical classical relation at zero temperature and zero entropy, describing the volume energy and surface energy change respectively. Since there is no event horizon, the Schwarzschild time t of such a non-singular gravitational condensate star is a global time, fully consistent with unitary time evolution in quantum theory. The $p=-\bar\rho$ interior acts as a defocusing lens for light passing through the condensate, leading to imaging characteristics distinguishable from a classical black hole. A further observational test of gravitational condensate stars with a physical surface vs. black holes is the discrete surface modes of oscillation which should be detectable by their gravitational wave signatures.
|
2105.07813
|
Sarmistha Banik
|
K Nobleson, Tuhin Malik and Sarmistha Banik
|
Tidal deformability of neutron stars with exotic particles within a
density dependent relativistic mean field model in R-squared gravity
|
4 figures. arXiv admin note: text overlap with arXiv:1803.09534 by
other authors
|
JCAP08(2021)012
|
10.1088/1475-7516/2021/08/012
| null |
gr-qc astro-ph.HE
|
http://creativecommons.org/licenses/by/4.0/
|
There is a growing interest in investigating modified theories of gravity,
primarily, with the aim of explaining the universe's accelerated expansion,
which has been confirmed by several independent observations. Compact objects,
like neutron stars, exhibit strong gravity effects and therefore are used to
study modified gravity theories. We use the $f(R)=R+aR^2$ model, where R is the
Ricci scalar and $a$ is a free parameter. This model has been studied both
perturbatively and non-perturbatively. However, it was found that perturbative
methods results in nonphysical solutions for the neutron stars. In this paper,
we examine neutron star properties, such as mass, radius, tidal deformability
in non-perturbative $f(R)$ gravity model with density dependant relativistic
equation of state with different particle compositions. The strange particles
in the core of NS in the form of ${\bf \Lambda}$ hyperons, $K^-$ condensate,
and quarks are considered. We have observed that while the mass-radius relation
allows for a wide range of parameter $a$, when tidal deformability is
considered, the parameter $a$ is constrained down by one order.
|
[
{
"created": "Thu, 13 May 2021 21:06:35 GMT",
"version": "v1"
},
{
"created": "Tue, 25 May 2021 08:04:34 GMT",
"version": "v2"
},
{
"created": "Tue, 6 Jul 2021 16:23:12 GMT",
"version": "v3"
}
] |
2021-08-16
|
[
[
"Nobleson",
"K",
""
],
[
"Malik",
"Tuhin",
""
],
[
"Banik",
"Sarmistha",
""
]
] |
There is a growing interest in investigating modified theories of gravity, primarily, with the aim of explaining the universe's accelerated expansion, which has been confirmed by several independent observations. Compact objects, like neutron stars, exhibit strong gravity effects and therefore are used to study modified gravity theories. We use the $f(R)=R+aR^2$ model, where R is the Ricci scalar and $a$ is a free parameter. This model has been studied both perturbatively and non-perturbatively. However, it was found that perturbative methods results in nonphysical solutions for the neutron stars. In this paper, we examine neutron star properties, such as mass, radius, tidal deformability in non-perturbative $f(R)$ gravity model with density dependant relativistic equation of state with different particle compositions. The strange particles in the core of NS in the form of ${\bf \Lambda}$ hyperons, $K^-$ condensate, and quarks are considered. We have observed that while the mass-radius relation allows for a wide range of parameter $a$, when tidal deformability is considered, the parameter $a$ is constrained down by one order.
|
gr-qc/0406056
|
C. S. Unnikrishnan
|
C. S. Unnikrishnan (Tata Institute, Mumbai)
|
Casimir Energy Density at Planck Time: Cosmic Coincidence or Double
Solution to the Cosmological Dark Energy Problem?
|
LaTex, 12 pt. 5 pages
| null | null | null |
gr-qc astro-ph
| null |
The Casimir energy density calculated for a spherical shell of radius equal
to the size of the Universe projected back to the Planck time is almost equal
to the present day critical density. Is it just a coincidence, or is it a
solution to the `cosmic dark energy' and the `cosmic coincidence' problems? The
correspondence is too close to be ignored as a coincidence, especially since
this solution fits the conceptual and numerical ideas about the dark energy,
and also answers why this energy is starting to dominate at the present era in
the evolution of the Universe.
|
[
{
"created": "Sun, 13 Jun 2004 17:48:09 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Unnikrishnan",
"C. S.",
"",
"Tata Institute, Mumbai"
]
] |
The Casimir energy density calculated for a spherical shell of radius equal to the size of the Universe projected back to the Planck time is almost equal to the present day critical density. Is it just a coincidence, or is it a solution to the `cosmic dark energy' and the `cosmic coincidence' problems? The correspondence is too close to be ignored as a coincidence, especially since this solution fits the conceptual and numerical ideas about the dark energy, and also answers why this energy is starting to dominate at the present era in the evolution of the Universe.
|
2212.00675
|
Quentin Vigneron
|
Quentin Vigneron, Vivian Poulin
|
Is expansion blind to the spatial curvature?
|
22+4 pages, 2 figures, 2 tables. Accepted for publication in Physical
Review D
| null | null | null |
gr-qc astro-ph.CO
|
http://creativecommons.org/licenses/by/4.0/
|
In [arXiv:2204.13980], we proposed and motivated a modification of the
Einstein equation as a function of the topology of the Universe in the form of
a bi-connection theory. The new equation features an additional "topological
term" related to a second non-dynamical reference connection and chosen as a
function of the spacetime topology. In the present paper, we analyse the
consequences for cosmology of this modification. First, we show that expansion
becomes blind to the spatial curvature in this new theory, i.e. the expansion
laws do not feature the spatial curvature parameter anymore (i.e.
$\Omega_{\not= K} = 1, \ \forall \, \Omega_K$), while this curvature is still
present in the evaluation of distances. Second, we derive the first order
perturbations of this homogeneous solution. Two additional gauge invariant
variables coming from the reference connection are present compared with
general relativity: a scalar and a vector mode, both sourced by the shear of
the cosmic fluid. Finally, we confront this model with observations. The
differences with the $\Lambda$CDM model are negligible, in particular, the
Hubble and curvature tensions are still present. Nevertheless, since the main
difference between the two models is the influence of the background spatial
curvature on the dynamics, an increased precision on the measure of that
parameter might allow us to observationally distinguish them.
|
[
{
"created": "Thu, 1 Dec 2022 17:30:57 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Sep 2023 19:22:38 GMT",
"version": "v2"
},
{
"created": "Tue, 31 Oct 2023 14:55:20 GMT",
"version": "v3"
}
] |
2023-11-01
|
[
[
"Vigneron",
"Quentin",
""
],
[
"Poulin",
"Vivian",
""
]
] |
In [arXiv:2204.13980], we proposed and motivated a modification of the Einstein equation as a function of the topology of the Universe in the form of a bi-connection theory. The new equation features an additional "topological term" related to a second non-dynamical reference connection and chosen as a function of the spacetime topology. In the present paper, we analyse the consequences for cosmology of this modification. First, we show that expansion becomes blind to the spatial curvature in this new theory, i.e. the expansion laws do not feature the spatial curvature parameter anymore (i.e. $\Omega_{\not= K} = 1, \ \forall \, \Omega_K$), while this curvature is still present in the evaluation of distances. Second, we derive the first order perturbations of this homogeneous solution. Two additional gauge invariant variables coming from the reference connection are present compared with general relativity: a scalar and a vector mode, both sourced by the shear of the cosmic fluid. Finally, we confront this model with observations. The differences with the $\Lambda$CDM model are negligible, in particular, the Hubble and curvature tensions are still present. Nevertheless, since the main difference between the two models is the influence of the background spatial curvature on the dynamics, an increased precision on the measure of that parameter might allow us to observationally distinguish them.
|
1104.4062
|
Jorge A. Rueda
|
Jorge A. Rueda, R. Ruffini, S.-S. Xue
|
The Klein first integrals in an equilibrium system with electromagnetic,
weak, strong and gravitational interactions
|
To be published by Nuclear Physics A
|
Nuclear Physics A, Volume 872, Issue 1, 286-295 (2011)
|
10.1016/j.nuclphysa.2011.09.005
| null |
gr-qc astro-ph.SR nucl-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The isothermal Tolman condition and the constancy of the Klein potentials
originally expressed for the sole gravitational interaction in a single fluid
are here generalized to the case of a three quantum fermion fluid duly taking
into account the strong, electromagnetic, weak and gravitational interactions.
The set of constitutive equations including the Einstein-Maxwell-Thomas-Fermi
equations as well as the ones corresponding to the strong interaction
description are here presented in the most general relativistic isothermal
case. This treatment represents an essential step to correctly formulate a
self-consistent relativistic field theoretical approach of neutron stars.
|
[
{
"created": "Wed, 20 Apr 2011 15:45:27 GMT",
"version": "v1"
},
{
"created": "Tue, 10 May 2011 16:50:20 GMT",
"version": "v2"
},
{
"created": "Fri, 24 Jun 2011 08:32:16 GMT",
"version": "v3"
},
{
"created": "Thu, 11 Aug 2011 17:58:06 GMT",
"version": "v4"
},
{
"created": "Tue, 13 Sep 2011 13:37:30 GMT",
"version": "v5"
}
] |
2012-06-01
|
[
[
"Rueda",
"Jorge A.",
""
],
[
"Ruffini",
"R.",
""
],
[
"Xue",
"S. -S.",
""
]
] |
The isothermal Tolman condition and the constancy of the Klein potentials originally expressed for the sole gravitational interaction in a single fluid are here generalized to the case of a three quantum fermion fluid duly taking into account the strong, electromagnetic, weak and gravitational interactions. The set of constitutive equations including the Einstein-Maxwell-Thomas-Fermi equations as well as the ones corresponding to the strong interaction description are here presented in the most general relativistic isothermal case. This treatment represents an essential step to correctly formulate a self-consistent relativistic field theoretical approach of neutron stars.
|
2210.04425
|
Vladimir Folomeev
|
Vladimir Dzhunushaliev, Vladimir Folomeev, Burkhard Kleihaus, and
Jutta Kunz
|
Mixed neutron-star-plus-wormhole systems: Rotating configurations
|
10 pages, 1 figure, minor corrections to content, version published
in PRD
|
Phys. Rev. D 107, 044060 (2023)
|
10.1103/PhysRevD.107.044060
| null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
We present rapidly rotating neutron stars featuring wormholes in their
centers. They arise in general relativity in the presence of a ghost scalar
field. The nuclear matter is described by a polytropic equation of state,
yielding realistic masses and radii for the neutron stars. The wormholes
possess small circumferential radii of size up to 3 km. With increasing
wormhole size, the masses and radii of the stars decrease, while the domain of
existence of these rotating mixed neutron-star-plus-wormhole systems retains
the characteristic properties of a rotating neutron star domain. The question
of stability of the mixed configurations under consideration is briefly
discussed.
|
[
{
"created": "Mon, 10 Oct 2022 04:02:43 GMT",
"version": "v1"
},
{
"created": "Sat, 25 Feb 2023 10:43:57 GMT",
"version": "v2"
}
] |
2023-02-28
|
[
[
"Dzhunushaliev",
"Vladimir",
""
],
[
"Folomeev",
"Vladimir",
""
],
[
"Kleihaus",
"Burkhard",
""
],
[
"Kunz",
"Jutta",
""
]
] |
We present rapidly rotating neutron stars featuring wormholes in their centers. They arise in general relativity in the presence of a ghost scalar field. The nuclear matter is described by a polytropic equation of state, yielding realistic masses and radii for the neutron stars. The wormholes possess small circumferential radii of size up to 3 km. With increasing wormhole size, the masses and radii of the stars decrease, while the domain of existence of these rotating mixed neutron-star-plus-wormhole systems retains the characteristic properties of a rotating neutron star domain. The question of stability of the mixed configurations under consideration is briefly discussed.
|
gr-qc/9904041
|
Wai-Mo Suen
|
Mark Miller, Wai-Mo Suen and Malcolm Tobias
|
The Shapiro Conjecture: Prompt or Delayed Collapse in the head-on
collision of neutron stars?
|
4 pages, 7 figures
|
Phys.Rev.D63:121501,2001
|
10.1103/PhysRevD.63.121501
| null |
gr-qc astro-ph
| null |
We study the question of prompt vs. delayed collapse in the head-on collision
of two neutron stars. We show that the prompt formation of a black hole is
possible, contrary to a conjecture of Shapiro which claims that collapse is
delayed until after neutrino cooling. We discuss the insight provided by
Shapiro's conjecture and its limitation. An understanding of the limitation of
the conjecture is provided in terms of the many time scales involved in the
problem. General relativistic simulations in the Einstein theory with the full
set of Einstein equations coupled to the general relativistic hydrodynamic
equations are carried out in our study.
|
[
{
"created": "Mon, 19 Apr 1999 22:43:36 GMT",
"version": "v1"
}
] |
2009-12-31
|
[
[
"Miller",
"Mark",
""
],
[
"Suen",
"Wai-Mo",
""
],
[
"Tobias",
"Malcolm",
""
]
] |
We study the question of prompt vs. delayed collapse in the head-on collision of two neutron stars. We show that the prompt formation of a black hole is possible, contrary to a conjecture of Shapiro which claims that collapse is delayed until after neutrino cooling. We discuss the insight provided by Shapiro's conjecture and its limitation. An understanding of the limitation of the conjecture is provided in terms of the many time scales involved in the problem. General relativistic simulations in the Einstein theory with the full set of Einstein equations coupled to the general relativistic hydrodynamic equations are carried out in our study.
|
1601.03106
|
J\"org Hennig
|
J\"org Hennig
|
New Gowdy-symmetric vacuum and electrovacuum solutions
|
25 pages, 2 figures
|
Class. Quantum Grav. 33, 135005 (2016)
|
10.1088/0264-9381/33/13/135005
| null |
gr-qc math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We construct a 4-parameter family of inhomogeneous cosmological models, which
contains two recently derived 3-parameter families as special cases. The
corresponding exact vacuum solution to Einstein's field equations is obtained
with methods from soliton theory. We also study properties of these models and
find that they combine all interesting features of both earlier solution
families: general regularity within the maximal globally hyperbolic region,
particular singular cases in which a curvature singularity with a directional
behaviour forms, a highly non-trivial causal structure, and Cauchy horizons
whose null generators can have both closed or non-closed orbits. In the second
part of the paper, we discuss the generalization from vacuum to electrovacuum.
Moreover, we also present a family of exact solutions for that case and study
its properties.
|
[
{
"created": "Wed, 13 Jan 2016 00:49:40 GMT",
"version": "v1"
},
{
"created": "Thu, 2 Jun 2016 00:54:45 GMT",
"version": "v2"
}
] |
2016-06-03
|
[
[
"Hennig",
"Jörg",
""
]
] |
We construct a 4-parameter family of inhomogeneous cosmological models, which contains two recently derived 3-parameter families as special cases. The corresponding exact vacuum solution to Einstein's field equations is obtained with methods from soliton theory. We also study properties of these models and find that they combine all interesting features of both earlier solution families: general regularity within the maximal globally hyperbolic region, particular singular cases in which a curvature singularity with a directional behaviour forms, a highly non-trivial causal structure, and Cauchy horizons whose null generators can have both closed or non-closed orbits. In the second part of the paper, we discuss the generalization from vacuum to electrovacuum. Moreover, we also present a family of exact solutions for that case and study its properties.
|
0806.0241
|
Tomilchik Lev
|
L. M. Tomilchik
|
Hubble law, Accelerating Universe and Pioneer Anomaly as effects of the
space-time conformal geometry
|
Reported on International Seminar "Modern Problems of the Particle
Physics" dedicated to Prof. I. L. Solovtsov momory, 17 January 2008, JINR,
Dubna, Russia
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The description of the cosmological expansion and its possible local
manifestations via treating the proper conformal transformations as a
coordinate transformation from a comoving Lorentz reference frame to an
uniformly accelerated one is given. The explicit form of the conformal time
inhomogeneity is established. The expression defining the location cosmological
distance in the form of simple function on the red shift is obtained. By
coupling it with the relativistic formula for the longitudinal Doppler effect,
the explicit expression for the Hubble law is obtained, which gives rise to the
connection between acceleration and the Hubble constant. The expression
generalizing the conventional Hubble law reproduces kinematically the
experimentally observed phenomenon treated conventionally as a Dark Energy
manifestation. The conformal time deformation in the small time limit leads to
the quadratic time nonlinearity. Being applied to describe the location-type
experiments, this predicts the existence of the universal uniformly changing
blue-shifted frequency drift. The obtained formulae reproduce the Pioneer
Anomaly experimental data.
|
[
{
"created": "Mon, 2 Jun 2008 09:59:53 GMT",
"version": "v1"
}
] |
2008-06-03
|
[
[
"Tomilchik",
"L. M.",
""
]
] |
The description of the cosmological expansion and its possible local manifestations via treating the proper conformal transformations as a coordinate transformation from a comoving Lorentz reference frame to an uniformly accelerated one is given. The explicit form of the conformal time inhomogeneity is established. The expression defining the location cosmological distance in the form of simple function on the red shift is obtained. By coupling it with the relativistic formula for the longitudinal Doppler effect, the explicit expression for the Hubble law is obtained, which gives rise to the connection between acceleration and the Hubble constant. The expression generalizing the conventional Hubble law reproduces kinematically the experimentally observed phenomenon treated conventionally as a Dark Energy manifestation. The conformal time deformation in the small time limit leads to the quadratic time nonlinearity. Being applied to describe the location-type experiments, this predicts the existence of the universal uniformly changing blue-shifted frequency drift. The obtained formulae reproduce the Pioneer Anomaly experimental data.
|
1212.2689
|
Carlos A. Batista da S. Filho
|
Carlos Batista and Bruno Carneiro da Cunha
|
Spinors and the Weyl Tensor Classification in Six Dimensions
|
23 pages; This version matches the published one
|
J. Math. Phys. 54 (2013), 052502
|
10.1063/1.4804991
| null |
gr-qc hep-th math.DG
|
http://creativecommons.org/licenses/by/3.0/
|
A spinorial approach to 6-dimensional differential geometry is constructed
and used to analyze tensor fields of low rank, with special attention to the
Weyl tensor. We perform a study similar to the 4-dimensional case, making full
use of the SO(6) symmetry to uncover results not easily seen in the tensorial
approach. Using spinors, we propose a classification of the Weyl tensor by
reinterpreting it as a map from 3-vectors to 3-vectors. This classification is
shown to be intimately related to the integrability of maximally isotropic
subspaces, establishing a natural framework to generalize the Goldberg-Sachs
theorem. We work in complexified spaces, showing that the results for any
signature can be obtained by taking the desired real slice.
|
[
{
"created": "Wed, 12 Dec 2012 02:12:44 GMT",
"version": "v1"
},
{
"created": "Wed, 5 Jun 2013 19:27:14 GMT",
"version": "v2"
}
] |
2013-06-06
|
[
[
"Batista",
"Carlos",
""
],
[
"da Cunha",
"Bruno Carneiro",
""
]
] |
A spinorial approach to 6-dimensional differential geometry is constructed and used to analyze tensor fields of low rank, with special attention to the Weyl tensor. We perform a study similar to the 4-dimensional case, making full use of the SO(6) symmetry to uncover results not easily seen in the tensorial approach. Using spinors, we propose a classification of the Weyl tensor by reinterpreting it as a map from 3-vectors to 3-vectors. This classification is shown to be intimately related to the integrability of maximally isotropic subspaces, establishing a natural framework to generalize the Goldberg-Sachs theorem. We work in complexified spaces, showing that the results for any signature can be obtained by taking the desired real slice.
|
2304.07383
|
Alexander Simpson
|
Alex Simpson
|
Excising Curvature Singularities from General Relativity
|
PhD Thesis; 276 pages; 42 figures; 429 references. v1
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
This thesis operates within the framework of general relativity without
curvature singularities. The motivation for this framework is explored, and
several conclusions are drawn with a look towards future research. There are
many ways to excise curvature singularities from general relativity; a full
list of desirable constraints on candidate geometries is presented. Several
specific candidate spacetimes in both spherical symmetry and axisymmetry are
rigorously analysed, typically modelling (charged or uncharged) regular black
holes or traversable wormholes. Broadly, these are members of the family of
black-bounce spacetimes, and the family of black holes with asymptotically
Minkowski cores. Related thin-shell traversable wormhole constructions are also
explored, as well as a brief look at the viability of thin-shell Dyson
mega-spheres. The eye of the storm geometry is analysed, and discovered to be
very close to an idealised candidate geometry within this framework. It is
found to contain highly desirable features, and is not precluded by currently
available measurements. For all spacetimes discussed, particular focus is
placed on the extraction of (potential) astrophysical observables in principle
falsifiable/verifiable by the observational and experimental communities. A
cogent effort is made to streamline the discourse between theory and
experiment, and to begin filling the epistemological gap, which will enable the
various communities involved to optimise the advancement of physics via the
newly available observational technologies (such as LIGO/Virgo, and the
upcoming LISA). Furthermore, three somewhat general theorems are presented, and
two new geometries are introduced for the first time to the literature.
|
[
{
"created": "Fri, 14 Apr 2023 20:32:36 GMT",
"version": "v1"
}
] |
2023-04-18
|
[
[
"Simpson",
"Alex",
""
]
] |
This thesis operates within the framework of general relativity without curvature singularities. The motivation for this framework is explored, and several conclusions are drawn with a look towards future research. There are many ways to excise curvature singularities from general relativity; a full list of desirable constraints on candidate geometries is presented. Several specific candidate spacetimes in both spherical symmetry and axisymmetry are rigorously analysed, typically modelling (charged or uncharged) regular black holes or traversable wormholes. Broadly, these are members of the family of black-bounce spacetimes, and the family of black holes with asymptotically Minkowski cores. Related thin-shell traversable wormhole constructions are also explored, as well as a brief look at the viability of thin-shell Dyson mega-spheres. The eye of the storm geometry is analysed, and discovered to be very close to an idealised candidate geometry within this framework. It is found to contain highly desirable features, and is not precluded by currently available measurements. For all spacetimes discussed, particular focus is placed on the extraction of (potential) astrophysical observables in principle falsifiable/verifiable by the observational and experimental communities. A cogent effort is made to streamline the discourse between theory and experiment, and to begin filling the epistemological gap, which will enable the various communities involved to optimise the advancement of physics via the newly available observational technologies (such as LIGO/Virgo, and the upcoming LISA). Furthermore, three somewhat general theorems are presented, and two new geometries are introduced for the first time to the literature.
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