id stringlengths 9 13 | submitter stringlengths 1 64 ⌀ | authors stringlengths 5 22.9k | title stringlengths 4 245 | comments stringlengths 1 548 ⌀ | journal-ref stringlengths 4 362 ⌀ | doi stringlengths 12 82 ⌀ | report-no stringlengths 2 281 ⌀ | categories stringclasses 793 values | license stringclasses 9 values | orig_abstract stringlengths 24 1.95k | versions listlengths 1 30 | update_date stringlengths 10 10 | authors_parsed listlengths 1 1.74k | abstract stringlengths 21 1.95k |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
2406.13654 | Lorenzo Pompili | F\'elix-Louis Juli\'e, Lorenzo Pompili, Alessandra Buonanno | Inspiral-merger-ringdown waveforms in Einstein-scalar-Gauss-Bonnet
gravity within the effective-one-body formalism | 33 pages, 11 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Gravitational waves (GWs) provide a unique opportunity to test General
Relativity (GR) in the highly dynamical, strong-field regime. So far, the
majority of the tests of GR with GW signals have been carried out following
parametrized, theory-independent approaches. An alternative avenue consists in
developing inspiral-merger-ringdown (IMR) waveform models in specific beyond-GR
theories of gravity, by combining analytical and numerical-relativity results.
In this work, we provide the first example of a full IMR waveform model in a
beyond-GR theory, focusing on Einstein-scalar-Gauss-Bonnet (ESGB) gravity. This
theory has attracted particular attention due to its rich phenomenology for
binary black-hole (BH) mergers, thanks to the presence of non-trivial scalar
fields. Starting from the state-of-the art, effective-one-body (EOB) multipolar
waveform model for spin-precessing binary BHs SEOBNRv5PHM, we include
theory-specific corrections to the EOB Hamiltonian, the metric and scalar
energy fluxes, the GW modes, the quasi-normal-mode (QNM) spectrum and the mass
and spin of the remnant BH. We also propose a way to marginalize over the
uncertainty in the merger morphology with additional nuisance parameters.
Interestingly, we observe that changes in the frequency of the ringdown
waveform due to the final mass and spin corrections are significantly larger
than those due to ESGB corrections to the QNM spectrum. By performing Bayesian
parameter estimation for the GW events GW190412, GW190814 and GW230529_181500,
we place constraints on the fundamental coupling of the theory
($\sqrt{\alpha_{\mathrm{GB}}} \lesssim 0.31~\mathrm{km}$ at 90% confidence).
The bound could be improved by one order of magnitude by observing a single
"golden" binary system with next-generation ground-based GW detectors.
| [
{
"created": "Wed, 19 Jun 2024 15:57:58 GMT",
"version": "v1"
}
] | 2024-06-21 | [
[
"Julié",
"Félix-Louis",
""
],
[
"Pompili",
"Lorenzo",
""
],
[
"Buonanno",
"Alessandra",
""
]
] | Gravitational waves (GWs) provide a unique opportunity to test General Relativity (GR) in the highly dynamical, strong-field regime. So far, the majority of the tests of GR with GW signals have been carried out following parametrized, theory-independent approaches. An alternative avenue consists in developing inspiral-merger-ringdown (IMR) waveform models in specific beyond-GR theories of gravity, by combining analytical and numerical-relativity results. In this work, we provide the first example of a full IMR waveform model in a beyond-GR theory, focusing on Einstein-scalar-Gauss-Bonnet (ESGB) gravity. This theory has attracted particular attention due to its rich phenomenology for binary black-hole (BH) mergers, thanks to the presence of non-trivial scalar fields. Starting from the state-of-the art, effective-one-body (EOB) multipolar waveform model for spin-precessing binary BHs SEOBNRv5PHM, we include theory-specific corrections to the EOB Hamiltonian, the metric and scalar energy fluxes, the GW modes, the quasi-normal-mode (QNM) spectrum and the mass and spin of the remnant BH. We also propose a way to marginalize over the uncertainty in the merger morphology with additional nuisance parameters. Interestingly, we observe that changes in the frequency of the ringdown waveform due to the final mass and spin corrections are significantly larger than those due to ESGB corrections to the QNM spectrum. By performing Bayesian parameter estimation for the GW events GW190412, GW190814 and GW230529_181500, we place constraints on the fundamental coupling of the theory ($\sqrt{\alpha_{\mathrm{GB}}} \lesssim 0.31~\mathrm{km}$ at 90% confidence). The bound could be improved by one order of magnitude by observing a single "golden" binary system with next-generation ground-based GW detectors. |
2003.10908 | Shambel Sahlu Akalu | Shambel Sahlu, Joseph Ntahompagaze, Amare Abebe and David F.Mota | Accelerating universe in modified teleparallel gravity theory | Conference proceeding: Nuclear Activity in Galaxies Across Cosmic
Time" (Ethiopia) accepted for publishing under the Cambridge University
Press, eds. M. Povic, P. Marziani, J. Masegosa, H. Netzer, S. H. Negu, and S.
B. Tessema | Proc. IAU 15 (2019) 397-399 | 10.1017/S1743921320003567 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper studies the cosmology of accelerating expansion of the universe in
modified teleparallel gravity theory. We discuss the cosmology of $f(T,B)$
gravity theory and its implication to the new general form of the equation of
state parameter $w_{TB}$ for explaining the late-time accelerating expansion of
the universe without the need for the cosmological constant scenario. We
examine the numerical value of $w_{TB}$ in different paradigmatic $f(T,B)$
gravity models. In those models, the numerical result of $w_{TB}$ is favored
with observations in the presence of the torsion scalar T associated with a
boundary term B and shows the accelerating expansion of the universe.
| [
{
"created": "Mon, 23 Mar 2020 12:59:23 GMT",
"version": "v1"
}
] | 2021-02-03 | [
[
"Sahlu",
"Shambel",
""
],
[
"Ntahompagaze",
"Joseph",
""
],
[
"Abebe",
"Amare",
""
],
[
"Mota",
"David F.",
""
]
] | This paper studies the cosmology of accelerating expansion of the universe in modified teleparallel gravity theory. We discuss the cosmology of $f(T,B)$ gravity theory and its implication to the new general form of the equation of state parameter $w_{TB}$ for explaining the late-time accelerating expansion of the universe without the need for the cosmological constant scenario. We examine the numerical value of $w_{TB}$ in different paradigmatic $f(T,B)$ gravity models. In those models, the numerical result of $w_{TB}$ is favored with observations in the presence of the torsion scalar T associated with a boundary term B and shows the accelerating expansion of the universe. |
1808.04423 | Saulo Carneiro | S. Carneiro and J. C. Fabris | Scalar field black holes | 8 pages, no figures | Eur. Phys. J. C (2018) 78: 676 | 10.1140/epjc/s10052-018-6161-x | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | With a suitable decomposition of its energy-momentum tensor into pressureless
matter and a vacuum type term, we investigate the spherical gravitational
collapse of a minimally coupled, self-interacting scalar field, showing that it
collapses to a singularity. The formed blackhole has a mass $M \sim 1/m$ (in
Planck units), where $m$ is the mass of the scalar field. If the latter has the
axion mass, $m \sim 10^{-5}$ eV, the former has a mass $M \sim 10^{-5}
M_{\odot}$.
| [
{
"created": "Mon, 13 Aug 2018 19:54:18 GMT",
"version": "v1"
}
] | 2018-08-27 | [
[
"Carneiro",
"S.",
""
],
[
"Fabris",
"J. C.",
""
]
] | With a suitable decomposition of its energy-momentum tensor into pressureless matter and a vacuum type term, we investigate the spherical gravitational collapse of a minimally coupled, self-interacting scalar field, showing that it collapses to a singularity. The formed blackhole has a mass $M \sim 1/m$ (in Planck units), where $m$ is the mass of the scalar field. If the latter has the axion mass, $m \sim 10^{-5}$ eV, the former has a mass $M \sim 10^{-5} M_{\odot}$. |
1702.04094 | Fabrizio Tamburini | Fabrizio Tamburini, Mariafelicia De Laurentis, Ignazio Licata, Bo
Thid\'e | Twisted soft photon hair implants on Black Holes | 6 pages 2 figures | null | 10.3390/e19090458 | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Hawking-Perry-Strominger (HPS) work [1] states a new controversial idea
about the black hole (BH) information paradox [2-5] where BHs maximally
entropize and encode information in their event horizon area [6,7], with no
"hair" were thought to reveal information outside but angular momentum, mass
and electric charge only [8,9] in a unique quantum gravity (QG) vacuum state.
This new idea invokes new conservation laws involving gravitation and
electromagnetism [10,11], to generate different QG vacua and preserve more
information in hair implants. In the context of black holes and the HPS
proposal we find that BH photon hair implants can be spatially shaped ad hoc
and encode structured and densely organized information on the event horizon
involving novel aspect in the discussion a particular aspect of EM fields,
namely the spatial information of the field associated to its orbital angular
momentum. BHs can have "curly", twisted, soft-hair implants with vorticity
where structured information is holographically encoded in the event horizon in
an organized way.
| [
{
"created": "Tue, 14 Feb 2017 07:00:21 GMT",
"version": "v1"
},
{
"created": "Thu, 11 May 2017 03:18:59 GMT",
"version": "v2"
}
] | 2017-10-11 | [
[
"Tamburini",
"Fabrizio",
""
],
[
"De Laurentis",
"Mariafelicia",
""
],
[
"Licata",
"Ignazio",
""
],
[
"Thidé",
"Bo",
""
]
] | The Hawking-Perry-Strominger (HPS) work [1] states a new controversial idea about the black hole (BH) information paradox [2-5] where BHs maximally entropize and encode information in their event horizon area [6,7], with no "hair" were thought to reveal information outside but angular momentum, mass and electric charge only [8,9] in a unique quantum gravity (QG) vacuum state. This new idea invokes new conservation laws involving gravitation and electromagnetism [10,11], to generate different QG vacua and preserve more information in hair implants. In the context of black holes and the HPS proposal we find that BH photon hair implants can be spatially shaped ad hoc and encode structured and densely organized information on the event horizon involving novel aspect in the discussion a particular aspect of EM fields, namely the spatial information of the field associated to its orbital angular momentum. BHs can have "curly", twisted, soft-hair implants with vorticity where structured information is holographically encoded in the event horizon in an organized way. |
2203.03633 | Dennis Obster | Dennis Obster | Tensors and Algebras: An Algebraic Spacetime Interpretation for Tensor
Models | null | SIGMA 19 (2023), 076, 43 pages | 10.3842/SIGMA.2023.076 | YITP-22-23 | gr-qc hep-th math-ph math.MP | http://creativecommons.org/licenses/by-sa/4.0/ | The quest for a consistent theory for quantum gravity is one of the most
challenging problems in theoretical high-energy physics. An often-used approach
is to describe the gravitational degrees of freedom by the metric tensor or
related variables, and finding a way to quantise this. In the canonical tensor
model, the gravitational degrees of freedom are encoded in a tensorial quantity
$P_{abc}$, and this quantity is subsequently quantised. This makes the
quantisation much more straightforward mathematically, but the interpretation
of this tensor as a spacetime is less evident. In this work we take a first
step towards fully understanding the relationship to spacetime. By considering
$P_{abc}$ as the generator of an algebra of functions, we first describe how we
can recover the topology and the measure of a compact Riemannian manifold.
Using the tensor rank decomposition, we then generalise this principle in order
to have a well-defined notion of the topology and geometry for a large class of
tensors $P_{abc}$. We provide some examples of the emergence of a topology and
measure of both exact and perturbed Riemannian manifolds, and of a purely
algebraically-defined space called the semi-local circle.
| [
{
"created": "Mon, 7 Mar 2022 06:54:57 GMT",
"version": "v1"
},
{
"created": "Wed, 18 Oct 2023 07:52:07 GMT",
"version": "v2"
}
] | 2023-10-19 | [
[
"Obster",
"Dennis",
""
]
] | The quest for a consistent theory for quantum gravity is one of the most challenging problems in theoretical high-energy physics. An often-used approach is to describe the gravitational degrees of freedom by the metric tensor or related variables, and finding a way to quantise this. In the canonical tensor model, the gravitational degrees of freedom are encoded in a tensorial quantity $P_{abc}$, and this quantity is subsequently quantised. This makes the quantisation much more straightforward mathematically, but the interpretation of this tensor as a spacetime is less evident. In this work we take a first step towards fully understanding the relationship to spacetime. By considering $P_{abc}$ as the generator of an algebra of functions, we first describe how we can recover the topology and the measure of a compact Riemannian manifold. Using the tensor rank decomposition, we then generalise this principle in order to have a well-defined notion of the topology and geometry for a large class of tensors $P_{abc}$. We provide some examples of the emergence of a topology and measure of both exact and perturbed Riemannian manifolds, and of a purely algebraically-defined space called the semi-local circle. |
1304.1325 | Matej Pavsic | Matej Pav\v{s}i\v{c} | Pais-Uhlenbeck Oscillator with a Benign Friction Force | 6 pages, 1 figure; reference added; typos corrected | Physical Review D 87, 107502 (2013) | 10.1103/PhysRevD.87.107502 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is shown that the Pais-Uhlenbeck oscillator with damping, considered by
Nesterenko, is a special case of a more general oscillator that has not only a
first order, but also a third order friction term. If the corresponding damping
constants, \alpha\ and \beta, are both positive and below certain critical
values, then the system is stable. In particular, if \alpha = - \beta, then we
have the unstable Nesterenko's oscillator
| [
{
"created": "Thu, 4 Apr 2013 11:17:06 GMT",
"version": "v1"
},
{
"created": "Thu, 23 May 2013 11:58:14 GMT",
"version": "v2"
}
] | 2013-05-24 | [
[
"Pavšič",
"Matej",
""
]
] | It is shown that the Pais-Uhlenbeck oscillator with damping, considered by Nesterenko, is a special case of a more general oscillator that has not only a first order, but also a third order friction term. If the corresponding damping constants, \alpha\ and \beta, are both positive and below certain critical values, then the system is stable. In particular, if \alpha = - \beta, then we have the unstable Nesterenko's oscillator |
gr-qc/0308081 | Charles Wang | Charles Wang | Action principle for nonlinear parametric quantization of gravity | 3 pages | null | null | null | gr-qc | null | The derivation of the recently proposed nonlinear quantum evolution of
gravity from an action principle is considered in this brief note. It is shown
to be possible if a set of consistency conditions are satisfied that are
analogous to the Dirac relations for the super-Hamiltonian and momenta in
classical canonical gravity.
| [
{
"created": "Mon, 25 Aug 2003 14:05:11 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Aug 2003 20:25:31 GMT",
"version": "v2"
},
{
"created": "Sun, 9 Nov 2003 11:44:28 GMT",
"version": "v3"
}
] | 2007-05-23 | [
[
"Wang",
"Charles",
""
]
] | The derivation of the recently proposed nonlinear quantum evolution of gravity from an action principle is considered in this brief note. It is shown to be possible if a set of consistency conditions are satisfied that are analogous to the Dirac relations for the super-Hamiltonian and momenta in classical canonical gravity. |
2407.09579 | Sanasam Surendra Singh | Meghanil Sinha, S. Surendra Singh | Gravastar model in the structure of $f(R,L_{m}, T)$ modified theory of
gravity | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Gravastar ( or the Gravitational Vacuum Star ) is a very serious
alternatives proposed to the principle of the Black Hole, the model of which
was originally developed by Mazur and Mottola. A Gravastar is an astronomically
hypothetically condensed object which is a gravitationally dark vacuum star or
a gravitational vacuum condensate star, which is singularity free, spherically
symmetric and also super compact. The current study concerns about the model of
the Gravastar in the modified $f(R,L_{m}, T)$ gravity considering the form
$f(R,L_{m},T) = R + {\alpha}TL_{m} $. From Mazur-Mottola
\cite{Mazur}-\cite{Mottola}, we get to know that a Gravastar model has three
distinct regions having various Equations of State (EoS). We have inquired into
the interior portion with the space-time considering $ \rho = - p $, for the
dark sector of the interior region, here the negative matter-energy density
exerting a repulsive force on the immediate thin shell with the EoS $ \rho = p
$ where it is considered as an ultra-relativistic fluid. We have studied the
properties such as energy density, proper length, total energy and entropy.
Next comes the vacuum exterior region of the Gravastar which is being described
by the Schwarzschild-de-Sitter solution. And also from Darmois-Israel
formalism, we have probed the junction connecting the inner and the outer
surfaces of the Gravastar.
| [
{
"created": "Fri, 12 Jul 2024 03:04:14 GMT",
"version": "v1"
}
] | 2024-07-16 | [
[
"Sinha",
"Meghanil",
""
],
[
"Singh",
"S. Surendra",
""
]
] | The Gravastar ( or the Gravitational Vacuum Star ) is a very serious alternatives proposed to the principle of the Black Hole, the model of which was originally developed by Mazur and Mottola. A Gravastar is an astronomically hypothetically condensed object which is a gravitationally dark vacuum star or a gravitational vacuum condensate star, which is singularity free, spherically symmetric and also super compact. The current study concerns about the model of the Gravastar in the modified $f(R,L_{m}, T)$ gravity considering the form $f(R,L_{m},T) = R + {\alpha}TL_{m} $. From Mazur-Mottola \cite{Mazur}-\cite{Mottola}, we get to know that a Gravastar model has three distinct regions having various Equations of State (EoS). We have inquired into the interior portion with the space-time considering $ \rho = - p $, for the dark sector of the interior region, here the negative matter-energy density exerting a repulsive force on the immediate thin shell with the EoS $ \rho = p $ where it is considered as an ultra-relativistic fluid. We have studied the properties such as energy density, proper length, total energy and entropy. Next comes the vacuum exterior region of the Gravastar which is being described by the Schwarzschild-de-Sitter solution. And also from Darmois-Israel formalism, we have probed the junction connecting the inner and the outer surfaces of the Gravastar. |
gr-qc/0104028 | Mauricio Cataldo | Mauricio Cataldo, Norman Cruz, Sergio del Campo and Samuel Lepe | Holographic principle and the dominant energy condition for Kasner type
metrics | 4 pages, Latex, accepted in Phys. Lett. B | Phys.Lett.B509:138-142,2001 | 10.1016/S0370-2693(01)00490-7 | null | gr-qc | null | In this letter we study adiabatic anisotropic matter filled Bianchi type I
models of the Kasner form together with the cosmological holographic bound. We
find that the dominant energy condition and the holographic bound give
precisely the same constraint on the scale factor parameters that appear in the
metric.
| [
{
"created": "Tue, 10 Apr 2001 21:53:19 GMT",
"version": "v1"
},
{
"created": "Thu, 12 Apr 2001 13:37:47 GMT",
"version": "v2"
}
] | 2009-02-05 | [
[
"Cataldo",
"Mauricio",
""
],
[
"Cruz",
"Norman",
""
],
[
"del Campo",
"Sergio",
""
],
[
"Lepe",
"Samuel",
""
]
] | In this letter we study adiabatic anisotropic matter filled Bianchi type I models of the Kasner form together with the cosmological holographic bound. We find that the dominant energy condition and the holographic bound give precisely the same constraint on the scale factor parameters that appear in the metric. |
1407.1483 | Roldao da Rocha | Roldao da Rocha, A. M. Kuerten | Classical Tests of General Relativity: Probing Topologically Charged
Black Holes on Brane Worlds in f(R) Bulk | 14 pages, 2 figures, to appear in Gen. Relat. Grav | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The perihelion precession, the deflection of light, and the radar echo delay
are classical tests of General Relativity here used to probe brane world
topologically charged black holes in a f(R) bulk and to constrain the parameter
that arises from the Shiromizu-Maeda-Sasaki procedure applied to a f(R) bulk as
well. The existing Solar system observational data constrain the possible
values of the tidal charge parameter and the effective cosmological constant
including f(R) brane world effects. We show that the observational/experimental
data for both perihelion precession and radar echo delay make the black hole
space of parameters to be more strict than the ones for the Dadhich, Maartens,
Papadopoulos and Rezania (DMPR) black hole geometry. Furthermore, the
deflection of light constrains the tidal charge parameter similarly as the DMPR
black holes due to a peculiarity in the equation of motion.
| [
{
"created": "Sun, 6 Jul 2014 11:20:58 GMT",
"version": "v1"
},
{
"created": "Tue, 8 Jul 2014 12:26:24 GMT",
"version": "v2"
},
{
"created": "Sat, 4 Jun 2016 22:41:26 GMT",
"version": "v3"
}
] | 2016-06-07 | [
[
"da Rocha",
"Roldao",
""
],
[
"Kuerten",
"A. M.",
""
]
] | The perihelion precession, the deflection of light, and the radar echo delay are classical tests of General Relativity here used to probe brane world topologically charged black holes in a f(R) bulk and to constrain the parameter that arises from the Shiromizu-Maeda-Sasaki procedure applied to a f(R) bulk as well. The existing Solar system observational data constrain the possible values of the tidal charge parameter and the effective cosmological constant including f(R) brane world effects. We show that the observational/experimental data for both perihelion precession and radar echo delay make the black hole space of parameters to be more strict than the ones for the Dadhich, Maartens, Papadopoulos and Rezania (DMPR) black hole geometry. Furthermore, the deflection of light constrains the tidal charge parameter similarly as the DMPR black holes due to a peculiarity in the equation of motion. |
1004.1016 | Piotr T. Chru\'sciel | Piotr T. Chru\'sciel and Gregory J. Galloway and Daniel Pollack | Mathematical general relativity: a sampler | Some updates. A shortened version, to appear in the Bulletin of the
AMS, is available online at
http://www.ams.org/journals/bull/0000-000-00/S0273-0979-2010-01304-5 | null | null | null | gr-qc math.AP math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide an introduction to selected recent advances in the mathematical
understanding of Einstein's theory of gravitation.
| [
{
"created": "Wed, 7 Apr 2010 07:01:21 GMT",
"version": "v1"
},
{
"created": "Tue, 3 Aug 2010 14:36:29 GMT",
"version": "v2"
}
] | 2015-03-14 | [
[
"Chruściel",
"Piotr T.",
""
],
[
"Galloway",
"Gregory J.",
""
],
[
"Pollack",
"Daniel",
""
]
] | We provide an introduction to selected recent advances in the mathematical understanding of Einstein's theory of gravitation. |
gr-qc/9905099 | Siming Liu | Fernando de Felice, Liu Siming and Yu Yunqiang | Relativistic Charged Spheres II: Regularity and Stability | revtex, 13 pages. five EPS figures. Accepted by CQG | Class.Quant.Grav. 16 (1999) 2669-2680 | 10.1088/0264-9381/16/8/307 | null | gr-qc | null | We present new results concerning the existence of static, electrically
charged, perfect fluid spheres that have a regular interior and are arbitrarily
close to a maximally charged black-hole state. These configurations are
described by exact solutions of Einstein's field equations. A family of these
solutions had already be found (de Felice et al., 1995) but here we generalize
that result to cases with different charge distribution within the spheres and
show, in an appropriate parameter space, that the set of such physically
reasonable solutions has a non zero measure. We also perform a perturbation
analysis and identify the solutions which are stable against adiabatic radial
perturbations. We then suggest that the stable configurations can be considered
as classic models of charged particles. Finally our results are used to show
that a conjecture of Kristiansson et al. (1998) is incorrect.
| [
{
"created": "Thu, 27 May 1999 14:44:02 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"de Felice",
"Fernando",
""
],
[
"Siming",
"Liu",
""
],
[
"Yunqiang",
"Yu",
""
]
] | We present new results concerning the existence of static, electrically charged, perfect fluid spheres that have a regular interior and are arbitrarily close to a maximally charged black-hole state. These configurations are described by exact solutions of Einstein's field equations. A family of these solutions had already be found (de Felice et al., 1995) but here we generalize that result to cases with different charge distribution within the spheres and show, in an appropriate parameter space, that the set of such physically reasonable solutions has a non zero measure. We also perform a perturbation analysis and identify the solutions which are stable against adiabatic radial perturbations. We then suggest that the stable configurations can be considered as classic models of charged particles. Finally our results are used to show that a conjecture of Kristiansson et al. (1998) is incorrect. |
gr-qc/9708003 | R. Balasubramanian | R. Balasubramanian, S.V. Dhurandhar | Estimation of parameters of gravitational waves from coalescing binaries | Revtex file with figures included(18) | Phys.Rev. D57 (1998) 3408-3422 | 10.1103/PhysRevD.57.3408 | IUCAA-97/xx | gr-qc | null | The paper deals with the estimation of parameters of gravitational waves from
coalescing binaries. It explains the discrepancy between the Monte carlo
simulations and the covariance matrix. We include the post-Newtonian as well as
the Newtonian case.
| [
{
"created": "Sun, 3 Aug 1997 04:18:33 GMT",
"version": "v1"
}
] | 2019-08-17 | [
[
"Balasubramanian",
"R.",
""
],
[
"Dhurandhar",
"S. V.",
""
]
] | The paper deals with the estimation of parameters of gravitational waves from coalescing binaries. It explains the discrepancy between the Monte carlo simulations and the covariance matrix. We include the post-Newtonian as well as the Newtonian case. |
1212.6821 | Theodore A. Jacobson | Ted Jacobson | Black holes and Hawking radiation in spacetime and its analogues | 31 pages, 9 figures; to appear in the proceedings of the IX SIGRAV
School on 'Analogue Gravity', Como (Italy), May 2011, eds. D. Faccio et. al.
(Springer) | null | 10.1007/978-3-319-00266-8_1 | null | gr-qc cond-mat.quant-gas hep-th physics.flu-dyn | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | These notes introduce the fundamentals of black hole geometry, the thermality
of the vacuum, and the Hawking effect, in spacetime and its analogues.
Stimulated emission of Hawking radiation, the trans-Planckian question, short
wavelength dispersion, and white hole radiation in the setting of analogue
models are also discussed. No prior knowledge of differential geometry, general
relativity, or quantum field theory in curved spacetime is assumed.
| [
{
"created": "Mon, 31 Dec 2012 05:12:38 GMT",
"version": "v1"
}
] | 2015-06-12 | [
[
"Jacobson",
"Ted",
""
]
] | These notes introduce the fundamentals of black hole geometry, the thermality of the vacuum, and the Hawking effect, in spacetime and its analogues. Stimulated emission of Hawking radiation, the trans-Planckian question, short wavelength dispersion, and white hole radiation in the setting of analogue models are also discussed. No prior knowledge of differential geometry, general relativity, or quantum field theory in curved spacetime is assumed. |
2305.07939 | Julio Arrechea | Julio Arrechea, Carlos Barcel\'o | Stellar equilibrium on a physical vacuum soil | 14 pages, 2 figures. Essay received Honorable Mention at the Gravity
Research Foundation 2023 Awards for Essays on Gravitation | null | 10.1142/S0218271823420063 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that the repulsive effects associated to the zero-point energies of
quantum fields are capable of supporting ultracompact stars that overcome the
compactness limits present in general relativity for any object in hydrostatic
equilibrium. These objects are exact self-consistent solutions in semiclassical
gravity that incorporate the backreaction of the renormalized stress-energy
tensor (RSET) of quantum fields in vacuum. We arrive at stars of striking
qualitative agreement through two independent modelings of the RSET, evidencing
the generality and robustness of this result. The main physical properties of
these novel black hole mimickers are reviewed.
| [
{
"created": "Sat, 13 May 2023 15:05:29 GMT",
"version": "v1"
}
] | 2023-09-26 | [
[
"Arrechea",
"Julio",
""
],
[
"Barceló",
"Carlos",
""
]
] | We show that the repulsive effects associated to the zero-point energies of quantum fields are capable of supporting ultracompact stars that overcome the compactness limits present in general relativity for any object in hydrostatic equilibrium. These objects are exact self-consistent solutions in semiclassical gravity that incorporate the backreaction of the renormalized stress-energy tensor (RSET) of quantum fields in vacuum. We arrive at stars of striking qualitative agreement through two independent modelings of the RSET, evidencing the generality and robustness of this result. The main physical properties of these novel black hole mimickers are reviewed. |
1009.5112 | Friedrich W. Hehl | Peter Baekler (Duesseldorf), Friedrich W. Hehl (Cologne and Columbia,
MO), James M. Nester (Chungli) | Poincare gauge theory of gravity: Friedman cosmology with even and odd
parity modes. Analytic part | Latex computerscript, 25 pages; mistakes corrected, references added,
notation and title slightly changed; accepted by Phys. Rev. D | Phys.Rev.D83:024001,2011 | 10.1103/PhysRevD.83.024001 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose a cosmological model in the framework of the Poincar\'e gauge
theory of gravity (PG). The gravitational Lagrangian is quadratic in curvature
and torsion. In our specific model, the Lagrangian contains (i) the curvature
scalar $R$ and the curvature pseudo-scalar $X$ linearly and quadratically
(including an $RX$ term) and (ii) pieces quadratic in the torsion {\it vector}
$\cal V$ and the torsion {\it axial} vector $\cal A$ (including a ${\cal
V}{\cal A}$ term). We show generally that in quadratic PG models we have nearly
the same number of parity conserving terms (`world') and of parity violating
terms (`shadow world'). This offers new perspectives in cosmology for the
coupling of gravity to matter and antimatter. Our specific model generalizes
the fairly realistic `torsion cosmologies' of Shie-Nester-Yo (2008) and Chen et
al.\ (2009). With a Friedman type ansatz for an orthonormal coframe and a
Lorentz connection, we derive the two field equations of PG in an explicit form
and discuss their general structure in detail. In particular, the second field
equation can be reduced to first order ordinary differential equations for the
curvature pieces $R(t)$ and $X(t)$. Including these along with certain
relations obtained from the first field equation and curvature definitions, we
present a first order system of equations suitable for numerical evaluation.
This is deferred to the second, numerical part of this paper.
| [
{
"created": "Sun, 26 Sep 2010 18:02:05 GMT",
"version": "v1"
},
{
"created": "Fri, 5 Nov 2010 23:52:14 GMT",
"version": "v2"
}
] | 2011-02-25 | [
[
"Baekler",
"Peter",
"",
"Duesseldorf"
],
[
"Hehl",
"Friedrich W.",
"",
"Cologne and Columbia,\n MO"
],
[
"Nester",
"James M.",
"",
"Chungli"
]
] | We propose a cosmological model in the framework of the Poincar\'e gauge theory of gravity (PG). The gravitational Lagrangian is quadratic in curvature and torsion. In our specific model, the Lagrangian contains (i) the curvature scalar $R$ and the curvature pseudo-scalar $X$ linearly and quadratically (including an $RX$ term) and (ii) pieces quadratic in the torsion {\it vector} $\cal V$ and the torsion {\it axial} vector $\cal A$ (including a ${\cal V}{\cal A}$ term). We show generally that in quadratic PG models we have nearly the same number of parity conserving terms (`world') and of parity violating terms (`shadow world'). This offers new perspectives in cosmology for the coupling of gravity to matter and antimatter. Our specific model generalizes the fairly realistic `torsion cosmologies' of Shie-Nester-Yo (2008) and Chen et al.\ (2009). With a Friedman type ansatz for an orthonormal coframe and a Lorentz connection, we derive the two field equations of PG in an explicit form and discuss their general structure in detail. In particular, the second field equation can be reduced to first order ordinary differential equations for the curvature pieces $R(t)$ and $X(t)$. Including these along with certain relations obtained from the first field equation and curvature definitions, we present a first order system of equations suitable for numerical evaluation. This is deferred to the second, numerical part of this paper. |
2108.06470 | Yan-Gang Miao | Yang Li and Yan-Gang Miao | Absorption cross section of regular black holes in scalar-tensor
conformal gravity | v1: 27 pages, 3 figures, 2 appendixes; v2: 28 pages, clarifications
added, final version to appear in Physical Review D | Phys. Rev. D 105 (2022) 044031 | 10.1103/PhysRevD.105.044031 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In terms of the complex angular momentum method, we compute the absorption
cross section by analyzing a massless test scalar field around conformally
related black holes. At first, we investigate circular null geodesics and
thereby prove a precondition for calculating the absorption cross section in
the context of conformally related black holes. Then we use the WKB
approximation method to derive the analytic expression of Regge frequency and
the oscillation part of absorption cross sections. We find that this
oscillation part depends on the scale factor of conformal transformations. By
taking the conformally related Schwarzschild-Tangherlini black hole as an
example, we show that this regular black hole has substantially distinctive
absorption behavior compared with singular black holes. Our result provides a
new approach to distinguish a regular black hole from a singular one.
| [
{
"created": "Sat, 14 Aug 2021 05:35:08 GMT",
"version": "v1"
},
{
"created": "Mon, 31 Jan 2022 08:41:04 GMT",
"version": "v2"
}
] | 2022-02-22 | [
[
"Li",
"Yang",
""
],
[
"Miao",
"Yan-Gang",
""
]
] | In terms of the complex angular momentum method, we compute the absorption cross section by analyzing a massless test scalar field around conformally related black holes. At first, we investigate circular null geodesics and thereby prove a precondition for calculating the absorption cross section in the context of conformally related black holes. Then we use the WKB approximation method to derive the analytic expression of Regge frequency and the oscillation part of absorption cross sections. We find that this oscillation part depends on the scale factor of conformal transformations. By taking the conformally related Schwarzschild-Tangherlini black hole as an example, we show that this regular black hole has substantially distinctive absorption behavior compared with singular black holes. Our result provides a new approach to distinguish a regular black hole from a singular one. |
1206.2580 | Oleg Zaslavskii | I. V. Tanatarov and O. B. Zaslavskii | Dirty rotating black holes: regularity conditions on stationary horizons | 31 pages. Misprints corrected | Phys. Rev. D 86 (2012) 044019 | 10.1103/PhysRevD.86.044019 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider generic, or "dirty" (surrounded by matter), stationary rotating
black holes with axial symmetry. The restrictions are found on the asymptotic
form of metric in the vicinity of non-extremal, extremal and ultra-extremal
horizons, imposed by the conditions of regularity of increasing strength:
boundedness on the horizon of the Ricci scalar, of scalar quadratic curvature
invariants, and of the components of the curvature tensor in the tetrad
attached to a falling observer. We show, in particular, that boundedness of the
Ricci scalar implies the "rigidity" of the horizon's rotation in all cases,
while the finiteness of quadratic invariants leads to the constancy of the
surface gravity. We discuss the role of quasiglobal coordinate r that is
emphasized by the conditions of regularity. Further restrictions on the metric
are formulated in terms of subsequent coefficients of expansion of metric
functions by r. The boundedness of the tetrad components of curvature tensor
for an observer crossing the horizon is shown to lead in the horizon limit to
diagonalization of Einstein tensor in the frame of zero angular momentum
observer on a circular orbit (ZAMO frame) for horizons of all degrees of
extremality.
| [
{
"created": "Tue, 12 Jun 2012 16:30:02 GMT",
"version": "v1"
},
{
"created": "Fri, 15 Jun 2012 20:54:04 GMT",
"version": "v2"
}
] | 2015-06-05 | [
[
"Tanatarov",
"I. V.",
""
],
[
"Zaslavskii",
"O. B.",
""
]
] | We consider generic, or "dirty" (surrounded by matter), stationary rotating black holes with axial symmetry. The restrictions are found on the asymptotic form of metric in the vicinity of non-extremal, extremal and ultra-extremal horizons, imposed by the conditions of regularity of increasing strength: boundedness on the horizon of the Ricci scalar, of scalar quadratic curvature invariants, and of the components of the curvature tensor in the tetrad attached to a falling observer. We show, in particular, that boundedness of the Ricci scalar implies the "rigidity" of the horizon's rotation in all cases, while the finiteness of quadratic invariants leads to the constancy of the surface gravity. We discuss the role of quasiglobal coordinate r that is emphasized by the conditions of regularity. Further restrictions on the metric are formulated in terms of subsequent coefficients of expansion of metric functions by r. The boundedness of the tetrad components of curvature tensor for an observer crossing the horizon is shown to lead in the horizon limit to diagonalization of Einstein tensor in the frame of zero angular momentum observer on a circular orbit (ZAMO frame) for horizons of all degrees of extremality. |
gr-qc/0110057 | Soon-Tae Hong | Soon-Tae Hong, Won Tae Kim, John J. Oh and Young-Jai Park | Global Embeddings of Two-dimensional Dilatonic Black Holes | 12 pages, no figures | J.Korean Phys.Soc.42:23-28,2003 | null | SOGANG-HEP 285/01 | gr-qc hep-th | null | We obtain minimal (2+1) and (2+2) dimensional global flat embeddings of
uncharged and charged dilatonic black holes in (1+1) dimensions, respectively.
Moreover, we obtain the Hawking temperatures and the black hole ones of these
dilatonic black holes. However, even though the minimal flat embedding
structures are mathematically meaningful, through this minimal embeddings the
proper entropies are shown to be unattainable, contrast to the cases of other
black holes in (2+1) or much higher dimensions.
| [
{
"created": "Thu, 11 Oct 2001 08:44:54 GMT",
"version": "v1"
},
{
"created": "Tue, 11 Feb 2003 05:40:28 GMT",
"version": "v2"
}
] | 2009-06-11 | [
[
"Hong",
"Soon-Tae",
""
],
[
"Kim",
"Won Tae",
""
],
[
"Oh",
"John J.",
""
],
[
"Park",
"Young-Jai",
""
]
] | We obtain minimal (2+1) and (2+2) dimensional global flat embeddings of uncharged and charged dilatonic black holes in (1+1) dimensions, respectively. Moreover, we obtain the Hawking temperatures and the black hole ones of these dilatonic black holes. However, even though the minimal flat embedding structures are mathematically meaningful, through this minimal embeddings the proper entropies are shown to be unattainable, contrast to the cases of other black holes in (2+1) or much higher dimensions. |
0907.2174 | Chris Clarkson | Sanjeev S. Seahra and Chris Clarkson | Gravitational waves in the black string braneworld | 16 pages, 8 figures | Class.Quant.Grav.26:245004,2009 | 10.1088/0264-9381/26/24/245004 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study gravitational waves in the black string Randall-Sundrum braneworld.
We present a reasonably self-contained and complete derivation of the equations
governing the evolution of gravitational perturbations in the presence of a
brane localized source, and then specialize to the case of spherical radiation
from a pointlike body in orbit around the black string. We solve for the
resulting gravitational waveform numerically for a number of different orbital
parameters.
| [
{
"created": "Mon, 13 Jul 2009 18:29:55 GMT",
"version": "v1"
}
] | 2009-11-19 | [
[
"Seahra",
"Sanjeev S.",
""
],
[
"Clarkson",
"Chris",
""
]
] | We study gravitational waves in the black string Randall-Sundrum braneworld. We present a reasonably self-contained and complete derivation of the equations governing the evolution of gravitational perturbations in the presence of a brane localized source, and then specialize to the case of spherical radiation from a pointlike body in orbit around the black string. We solve for the resulting gravitational waveform numerically for a number of different orbital parameters. |
1504.06583 | Jeff Steinhauer | Jeff Steinhauer | Measuring the entanglement of analogue Hawking radiation by the
density-density correlation function | The second version has a few additional explanatory sentences. The
third version has an improved introduction including additional citations | Phys. Rev. D 92, 024043 (2015) | 10.1103/PhysRevD.92.024043 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We theoretically study the entanglement of Hawking radiation pairs emitted by
an analogue black hole. We find that this entanglement can be measured by the
experimentally accessible density-density correlation function, vastly
simplifying the measurement. We find that while the Hawking radiation exiting
the black hole might be Planck-distributed, the correlations between the
Hawking radiation and the partner particles has a distribution which is weaker
but broader than Planckian. Thus, the high energy tail of the distribution of
Hawking radiation should be entangled, whereas the low energy part should not
be. This confirms a previous numerical study. The full Peres-Horodecki
criterion is considered, as well as a simpler criterion in the stationary,
homogeneous case. Our method applies to systems which are sufficiently cold
that the thermal phonons can be neglected.
| [
{
"created": "Fri, 24 Apr 2015 17:57:02 GMT",
"version": "v1"
},
{
"created": "Tue, 28 Apr 2015 13:30:17 GMT",
"version": "v2"
},
{
"created": "Wed, 20 May 2015 14:03:29 GMT",
"version": "v3"
}
] | 2015-08-04 | [
[
"Steinhauer",
"Jeff",
""
]
] | We theoretically study the entanglement of Hawking radiation pairs emitted by an analogue black hole. We find that this entanglement can be measured by the experimentally accessible density-density correlation function, vastly simplifying the measurement. We find that while the Hawking radiation exiting the black hole might be Planck-distributed, the correlations between the Hawking radiation and the partner particles has a distribution which is weaker but broader than Planckian. Thus, the high energy tail of the distribution of Hawking radiation should be entangled, whereas the low energy part should not be. This confirms a previous numerical study. The full Peres-Horodecki criterion is considered, as well as a simpler criterion in the stationary, homogeneous case. Our method applies to systems which are sufficiently cold that the thermal phonons can be neglected. |
gr-qc/0608094 | A. Latif Choudhury | A. M. Harunar Rashid, Arshad Momen, and A. L. Choudhury | Accelerating Universe Around A Blackhole | 9 pages | null | null | null | gr-qc | null | We have assumed that in a physical universe a blackhole is created some
where. We conjecture that this blackhole will then separate itself from the
physical universe and will build up an extra dimensional entity associated with
the physical universe. The extra dimensional entity we suppose to be orthogonal
to the physical universe. We further conjecture that this blackhole is a
Schwartzschild blackhole. We assume that this physical universe and the
blackhole span a seven dimensional space with a common time coordinate. We then
generate the Einstein equation. Using the time-blackhole and the time-time
component of the equation we show that the Hubble parameter is positive and
time dependent if we conjecture that both scale factor and the radius of the
blackhole reduces exponetially. Under the same assumption we have also
calculated the deacceleration parameter and shown that under certain constrain
the universe accelerates.
| [
{
"created": "Sun, 20 Aug 2006 02:48:51 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Rashid",
"A. M. Harunar",
""
],
[
"Momen",
"Arshad",
""
],
[
"Choudhury",
"A. L.",
""
]
] | We have assumed that in a physical universe a blackhole is created some where. We conjecture that this blackhole will then separate itself from the physical universe and will build up an extra dimensional entity associated with the physical universe. The extra dimensional entity we suppose to be orthogonal to the physical universe. We further conjecture that this blackhole is a Schwartzschild blackhole. We assume that this physical universe and the blackhole span a seven dimensional space with a common time coordinate. We then generate the Einstein equation. Using the time-blackhole and the time-time component of the equation we show that the Hubble parameter is positive and time dependent if we conjecture that both scale factor and the radius of the blackhole reduces exponetially. Under the same assumption we have also calculated the deacceleration parameter and shown that under certain constrain the universe accelerates. |
1706.07656 | Ali \"Ovg\"un Dr. | Ali \"Ovg\"un and Kimet Jusufi | Stability of Effective Thin-shell Wormholes Under Lorentz Symmetry
Breaking Supported by Dark Matter and Dark Energy | 13 pages, 9 figures, accepted for publication in Eur. Phys. J. Plus | Eur. Phys. J. Plus (2017) 132: 543 | 10.1140/epjp/i2017-11829-5 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we construct generic, spherically symmetric thin-shell
wormholes and check their stabilities using the unified dark sector, including
dark energy and dark matter. We give a master equation, from which one can
recover, as a special case, other stability solutions for generic spherically
symmetric thin-shell wormholes. In this context, we consider a particular
solution; namely we construct an effective thin-shell wormhole under Lorentz
symmetry breaking. We explore stability analyses using different models of the
modified Chaplygin gas with constraints from cosmological observations such as
seventh-year full Wilkinson microwave anisotropy probe data points, type Ia
supernovae, and baryon acoustic oscillation. In all these models we find stable
solutions by choosing suitable values for the parameters of the Lorentz
symmetry breaking effect.
| [
{
"created": "Thu, 22 Jun 2017 15:46:20 GMT",
"version": "v1"
},
{
"created": "Wed, 6 Dec 2017 13:42:17 GMT",
"version": "v2"
}
] | 2017-12-22 | [
[
"Övgün",
"Ali",
""
],
[
"Jusufi",
"Kimet",
""
]
] | In this paper, we construct generic, spherically symmetric thin-shell wormholes and check their stabilities using the unified dark sector, including dark energy and dark matter. We give a master equation, from which one can recover, as a special case, other stability solutions for generic spherically symmetric thin-shell wormholes. In this context, we consider a particular solution; namely we construct an effective thin-shell wormhole under Lorentz symmetry breaking. We explore stability analyses using different models of the modified Chaplygin gas with constraints from cosmological observations such as seventh-year full Wilkinson microwave anisotropy probe data points, type Ia supernovae, and baryon acoustic oscillation. In all these models we find stable solutions by choosing suitable values for the parameters of the Lorentz symmetry breaking effect. |
1708.09736 | Roberto Casadio | Roberto Casadio, Andrea Giugno, Andrea Giusti | Corpuscular slow-roll inflation | 6 pages, 1 figure, minor typos corrected | Phys. Rev. D 97, 024041 (2018) | 10.1103/PhysRevD.97.024041 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that a corpuscular description of gravity can lead to an inflationary
scenario similar to Starobinsky's model without requiring the introduction of
the inflaton field. All relevant properties are determined by the number of
gravitons in the cosmological condensate or, equivalently, by their Compton
length. In particular, the relation between the Hubble parameter $H$ and its
time derivative $\dot H$ required by CMB observations at the end of inflation,
as well as the (minimum) initial value of the slow-roll parameter, are
naturally obtained from the Compton size of the condensate.
| [
{
"created": "Thu, 31 Aug 2017 14:21:48 GMT",
"version": "v1"
},
{
"created": "Wed, 17 Jan 2018 08:38:29 GMT",
"version": "v2"
},
{
"created": "Mon, 29 Oct 2018 10:20:50 GMT",
"version": "v3"
}
] | 2018-10-30 | [
[
"Casadio",
"Roberto",
""
],
[
"Giugno",
"Andrea",
""
],
[
"Giusti",
"Andrea",
""
]
] | We show that a corpuscular description of gravity can lead to an inflationary scenario similar to Starobinsky's model without requiring the introduction of the inflaton field. All relevant properties are determined by the number of gravitons in the cosmological condensate or, equivalently, by their Compton length. In particular, the relation between the Hubble parameter $H$ and its time derivative $\dot H$ required by CMB observations at the end of inflation, as well as the (minimum) initial value of the slow-roll parameter, are naturally obtained from the Compton size of the condensate. |
2110.07278 | Foad Parsaei | Foad Parsaei and Sara Rastgoo | Wormhole in f(R) gravity revisited | 9 pages, 7 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, exact wormhole solutions in the context of $f(R)$ theory of
gravity are investigated. Since the Einstein field equations are modified in
3+1 dimensions in the $f(R)$ theory of gravity, we have studied some possible
solutions with different forms of shape function and $f(R)$ function. We show
that choosing $f(R)$ or metric functions arbitrarily may lead to a conflict for
wormhole solutions. Some previous solutions are discussed which verify the
contradiction throughout the equations. We conclude that wormhole solutions in
the context of $f(R)$ gravity should be revisited.
| [
{
"created": "Thu, 14 Oct 2021 11:30:27 GMT",
"version": "v1"
}
] | 2021-10-15 | [
[
"Parsaei",
"Foad",
""
],
[
"Rastgoo",
"Sara",
""
]
] | In this paper, exact wormhole solutions in the context of $f(R)$ theory of gravity are investigated. Since the Einstein field equations are modified in 3+1 dimensions in the $f(R)$ theory of gravity, we have studied some possible solutions with different forms of shape function and $f(R)$ function. We show that choosing $f(R)$ or metric functions arbitrarily may lead to a conflict for wormhole solutions. Some previous solutions are discussed which verify the contradiction throughout the equations. We conclude that wormhole solutions in the context of $f(R)$ gravity should be revisited. |
0904.0278 | Quentin G. Bailey | Quentin G. Bailey | Time-delay and Doppler tests of the Lorentz symmetry of gravity | 13 pages, 4 figures, references added, matches PRD version | Phys.Rev.D80:044004,2009 | 10.1103/PhysRevD.80.044004 | null | gr-qc astro-ph.EP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Modifications to the classic time-delay effect and Doppler shift in General
Relativity (GR) are studied in the context of the Lorentz-violating
Standard-Model Extension (SME). We derive the leading Lorentz-violating
corrections to the time-delay and Doppler shift signals, for a light ray
passing near a massive body. It is demonstrated that anisotropic coefficients
for Lorentz violation control a time-dependent behavior of these signals that
is qualitatively different from the conventional case in GR. Estimates of
sensitivities to gravity-sector coefficients in the SME are given for current
and future experiments, including the recent Cassini solar conjunction
experiment.
| [
{
"created": "Thu, 2 Apr 2009 00:14:31 GMT",
"version": "v1"
},
{
"created": "Wed, 12 Aug 2009 20:43:36 GMT",
"version": "v2"
}
] | 2009-10-29 | [
[
"Bailey",
"Quentin G.",
""
]
] | Modifications to the classic time-delay effect and Doppler shift in General Relativity (GR) are studied in the context of the Lorentz-violating Standard-Model Extension (SME). We derive the leading Lorentz-violating corrections to the time-delay and Doppler shift signals, for a light ray passing near a massive body. It is demonstrated that anisotropic coefficients for Lorentz violation control a time-dependent behavior of these signals that is qualitatively different from the conventional case in GR. Estimates of sensitivities to gravity-sector coefficients in the SME are given for current and future experiments, including the recent Cassini solar conjunction experiment. |
1601.06528 | Salvatore Capozziello | A. Paliathanasis, L. Karpathopoulos, A. Wojnar, and S. Capozziello | Wheeler-DeWitt equation and Lie symmetries in Bianchi scalar-field
cosmology | 17 pages | null | 10.1140/epjc/s10052-016-4087-8 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Lie symmetries are discussed for the Wheeler-De Witt equation in Bianchi
Class A cosmologies. In particular, we consider General Relativity, minimally
coupled scalar field gravity and Hybrid Gravity as paradigmatic examples of the
approach. Several invariant solutions are determined and classified according
to the form of the scalar field potential. The approach gives rise to a
suitable method to select classical solutions and it is based on the first
principle of the existence of symmetries.
| [
{
"created": "Mon, 25 Jan 2016 09:42:00 GMT",
"version": "v1"
}
] | 2016-05-25 | [
[
"Paliathanasis",
"A.",
""
],
[
"Karpathopoulos",
"L.",
""
],
[
"Wojnar",
"A.",
""
],
[
"Capozziello",
"S.",
""
]
] | Lie symmetries are discussed for the Wheeler-De Witt equation in Bianchi Class A cosmologies. In particular, we consider General Relativity, minimally coupled scalar field gravity and Hybrid Gravity as paradigmatic examples of the approach. Several invariant solutions are determined and classified according to the form of the scalar field potential. The approach gives rise to a suitable method to select classical solutions and it is based on the first principle of the existence of symmetries. |
1108.1826 | C\'edric Huwyler | C\'edric Huwyler, Antoine Klein, Philippe Jetzer | Testing General Relativity with LISA including Spin Precession and
Higher Harmonics in the Waveform | 33 pages, 37 figures | null | 10.1103/PhysRevD.86.084028 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compute the accuracy at which a LISA-like space-based gravitational wave
detector will be able to observe deviations from General Relativity in the low
frequency approximation. To do so, we introduce six correction parameters that
account for modified gravity in the second post-Newtonian gravitational wave
phase for inspiralling supermassive black hole binaries with spin precession on
quasi-circular orbits. Our implementation can be regarded as a subset of the
ppE formalism developed by Yunes and Pretorius, being able to investigate also
next-to-leading order effects. In order to find error distributions for the
alternative theory parameters, we use the Fisher information formalism and
carry out Monte Carlo simulations for 17 different binary black hole mass
configurations in the range 10^5 Msun < M < 10^8 Msun with 10^3 randomly
distributed points in the parameter space each, comparing the full (FWF) and
restricted (RWF) version of the gravitational waveform. We find that the
binaries can roughly be separated into two groups: one with low (< ~10^7 Msun)
and one with high total masses (> ~10^7 Msun). The RWF errors on the
alternative theory parameters are two orders of magnitude higher than the FWF
errors for high-mass binaries while almost comparable for low-mass binaries.
Due to dilution of the available information, the accuracy of the binary
parameters is reduced by factors of a few, except for the luminosity distance
which is affected more seriously in the high-mass regime. As an application and
to compare our research with previous work, we compute an optimal lower bound
on the graviton Compton wavelength which is increased by a factor of ~1.6 when
using the FWF.
| [
{
"created": "Mon, 8 Aug 2011 23:07:48 GMT",
"version": "v1"
},
{
"created": "Wed, 22 Aug 2012 09:39:22 GMT",
"version": "v2"
}
] | 2015-05-30 | [
[
"Huwyler",
"Cédric",
""
],
[
"Klein",
"Antoine",
""
],
[
"Jetzer",
"Philippe",
""
]
] | We compute the accuracy at which a LISA-like space-based gravitational wave detector will be able to observe deviations from General Relativity in the low frequency approximation. To do so, we introduce six correction parameters that account for modified gravity in the second post-Newtonian gravitational wave phase for inspiralling supermassive black hole binaries with spin precession on quasi-circular orbits. Our implementation can be regarded as a subset of the ppE formalism developed by Yunes and Pretorius, being able to investigate also next-to-leading order effects. In order to find error distributions for the alternative theory parameters, we use the Fisher information formalism and carry out Monte Carlo simulations for 17 different binary black hole mass configurations in the range 10^5 Msun < M < 10^8 Msun with 10^3 randomly distributed points in the parameter space each, comparing the full (FWF) and restricted (RWF) version of the gravitational waveform. We find that the binaries can roughly be separated into two groups: one with low (< ~10^7 Msun) and one with high total masses (> ~10^7 Msun). The RWF errors on the alternative theory parameters are two orders of magnitude higher than the FWF errors for high-mass binaries while almost comparable for low-mass binaries. Due to dilution of the available information, the accuracy of the binary parameters is reduced by factors of a few, except for the luminosity distance which is affected more seriously in the high-mass regime. As an application and to compare our research with previous work, we compute an optimal lower bound on the graviton Compton wavelength which is increased by a factor of ~1.6 when using the FWF. |
1105.5843 | Nelson Christensen | N.L. Christensen (for the LIGO Scientific Collaboration and the Virgo
Collaboration) | Multimessenger Astronomy | For the proceedings for the 46th Rencontres de Moriond and GPhyS
Colloquium on Gravitational Waves and Experimental Gravity | null | null | LIGO Document Number P-1100053 | gr-qc astro-ph.HE astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Multimessenger astronomy incorporating gravitational radiation is a new and
exciting field that will potentially provide significant results and exciting
challenges in the near future. With advanced interferometric gravitational wave
detectors (LCGT, LIGO, Virgo) we will have the opportunity to investigate
sources of gravitational waves that are also expected to be observable through
other messengers, such as electromagnetic (gamma-rays, x-rays, optical, radio)
and/or neutrino emission. The LIGO-Virgo interferometer network has already
been used for multimessenger searches for gravitational radiation that have
produced insights on cosmic events. The simultaneous observation of
electromagnetic and/or neutrino emission could be important evidence in the
first direct detection of gravitational radiation. Knowledge of event time,
source sky location, and the expected frequency range of the signal enhances
our ability to search for the gravitational radiation signatures with an
amplitude closer to the noise floor of the detector. Presented here is a
summary of the status of LIGO-Virgo multimessenger detection efforts, along
with a discussion of questions that might be resolved using the data from
advanced or third generation gravitational wave detector networks.
| [
{
"created": "Mon, 30 May 2011 00:42:09 GMT",
"version": "v1"
}
] | 2019-08-13 | [
[
"Christensen",
"N. L.",
"",
"for the LIGO Scientific Collaboration and the Virgo\n Collaboration"
]
] | Multimessenger astronomy incorporating gravitational radiation is a new and exciting field that will potentially provide significant results and exciting challenges in the near future. With advanced interferometric gravitational wave detectors (LCGT, LIGO, Virgo) we will have the opportunity to investigate sources of gravitational waves that are also expected to be observable through other messengers, such as electromagnetic (gamma-rays, x-rays, optical, radio) and/or neutrino emission. The LIGO-Virgo interferometer network has already been used for multimessenger searches for gravitational radiation that have produced insights on cosmic events. The simultaneous observation of electromagnetic and/or neutrino emission could be important evidence in the first direct detection of gravitational radiation. Knowledge of event time, source sky location, and the expected frequency range of the signal enhances our ability to search for the gravitational radiation signatures with an amplitude closer to the noise floor of the detector. Presented here is a summary of the status of LIGO-Virgo multimessenger detection efforts, along with a discussion of questions that might be resolved using the data from advanced or third generation gravitational wave detector networks. |
1504.02499 | John Poirier | J. Poirier and G. J. Mathews | Role of the gravitomagnetic field in accelerating accretion disk matter
to polar jets | 7 pages, 4 figures, typos corrected | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that the motion of the neutral masses in an accretion disk orbiting a
black hole creates a general-relativistic magnetic-like (gravitomagnetic) field
that vertically accelerates neutral particles near the accretion disk upward
and then inward toward the axis of the accretion disk. Even though this
gravitomagnetic field alone does not achieve collimated jets, it is a novel
means to identify one general relativistic effect from a much more complicated
problem. In addition, as the accelerated material above or below the accretion
disk nears the axis with a nearly vertical direction, a frame-dragging effect
twists the trajectories around the axis thus contributing to the formation of
collimated bipolar jets.
| [
{
"created": "Thu, 9 Apr 2015 21:11:39 GMT",
"version": "v1"
},
{
"created": "Fri, 17 Apr 2015 19:54:37 GMT",
"version": "v2"
}
] | 2015-04-20 | [
[
"Poirier",
"J.",
""
],
[
"Mathews",
"G. J.",
""
]
] | We show that the motion of the neutral masses in an accretion disk orbiting a black hole creates a general-relativistic magnetic-like (gravitomagnetic) field that vertically accelerates neutral particles near the accretion disk upward and then inward toward the axis of the accretion disk. Even though this gravitomagnetic field alone does not achieve collimated jets, it is a novel means to identify one general relativistic effect from a much more complicated problem. In addition, as the accelerated material above or below the accretion disk nears the axis with a nearly vertical direction, a frame-dragging effect twists the trajectories around the axis thus contributing to the formation of collimated bipolar jets. |
0805.3146 | Kenta Hioki | Kenta Hioki (Waseda Univ.), Umpei Miyamoto (Hebrew Univ.) | Hidden symmetries, null geodesics, and photon capture in the Sen black
hole | 19 pages, 6 figures, 1 table; v2: references added, typos corrected | Phys.Rev.D78:044007,2008 | 10.1103/PhysRevD.78.044007 | WU-AP/286/08 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Important classes of null geodesics and hidden symmetries in the Sen black
hole are investigated. First, we obtain the principal null geodesics and
circular photon orbits. Then, an irreducible rank-two Killing tensor and a
conformal Killing tensor are derived, which represent the hidden symmetries.
Analyzing the properties of Killing tensors, we clarify why the Hamilton-Jacobi
and wave equations are separable in this spacetime. We also investigate the
gravitational capture of photons by the Sen black hole and compare the result
with those by the various charged/rotating black holes and naked singularities
in the Kerr-Newman family. For these black holes and naked singularities, we
show the capture regions in a two dimensional impact parameter space (or
equivalently the ``shadows'' observed at infinity) to form a variety of shapes
such as the disk, circle, dot, arc, and their combinations.
| [
{
"created": "Tue, 20 May 2008 19:56:39 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Aug 2008 09:36:54 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Hioki",
"Kenta",
"",
"Waseda Univ."
],
[
"Miyamoto",
"Umpei",
"",
"Hebrew Univ."
]
] | Important classes of null geodesics and hidden symmetries in the Sen black hole are investigated. First, we obtain the principal null geodesics and circular photon orbits. Then, an irreducible rank-two Killing tensor and a conformal Killing tensor are derived, which represent the hidden symmetries. Analyzing the properties of Killing tensors, we clarify why the Hamilton-Jacobi and wave equations are separable in this spacetime. We also investigate the gravitational capture of photons by the Sen black hole and compare the result with those by the various charged/rotating black holes and naked singularities in the Kerr-Newman family. For these black holes and naked singularities, we show the capture regions in a two dimensional impact parameter space (or equivalently the ``shadows'' observed at infinity) to form a variety of shapes such as the disk, circle, dot, arc, and their combinations. |
0710.4131 | Ruxandra Bondarescu | Jayashree Balakrishna, Ruxandra Bondarescu, Gregory Daues, Mihai
Bondarescu | Numerical Simulations of Oscillating Soliton Stars: Excited States in
Spherical Symmetry and Ground State Evolutions in 3D | 12 pages, 11 figures, typos corrected, includes referee input,
references corrected, published version | Phys.Rev.D77:024028,2008 | 10.1103/PhysRevD.77.024028 | null | gr-qc | null | Excited state soliton stars are studied numerically for the first time. The
stability of spherically symmetric S-branch excited state oscillatons under
radial perturbations is investigated using a 1D code. We find that these stars
are inherently unstable either migrating to the ground state or collapsing to
black holes. Higher excited state configurations are observed to cascade
through intermediate excited states during their migration to the ground state.
This is similar to excited state boson stars. Ground state oscillatons are then
studied in full 3D numerical relativity. Finding the appropriate gauge
condition for the dynamic oscillatons is much more challenging than in the case
of boson stars. Different slicing conditions are explored, and a customized
gauge condition that approximates polar slicing in spherical symmetry is
implemented. Comparisons with 1D results and convergence tests are performed.
The behavior of these stars under small axisymmetric perturbations is studied
and gravitational waveforms are extracted. We find that the gravitational waves
damp out on a short timescale, enabling us to obtain the complete waveform.
This work is a starting point for the evolution of real scalar field systems
with arbitrary symmetries.
| [
{
"created": "Mon, 22 Oct 2007 19:58:44 GMT",
"version": "v1"
},
{
"created": "Mon, 22 Oct 2007 20:36:46 GMT",
"version": "v2"
},
{
"created": "Fri, 30 Nov 2007 17:02:10 GMT",
"version": "v3"
},
{
"created": "Wed, 5 Dec 2007 05:26:44 GMT",
"version": "v4"
},
{
"created": "Fri, 18 Jan 2008 17:48:00 GMT",
"version": "v5"
}
] | 2008-11-26 | [
[
"Balakrishna",
"Jayashree",
""
],
[
"Bondarescu",
"Ruxandra",
""
],
[
"Daues",
"Gregory",
""
],
[
"Bondarescu",
"Mihai",
""
]
] | Excited state soliton stars are studied numerically for the first time. The stability of spherically symmetric S-branch excited state oscillatons under radial perturbations is investigated using a 1D code. We find that these stars are inherently unstable either migrating to the ground state or collapsing to black holes. Higher excited state configurations are observed to cascade through intermediate excited states during their migration to the ground state. This is similar to excited state boson stars. Ground state oscillatons are then studied in full 3D numerical relativity. Finding the appropriate gauge condition for the dynamic oscillatons is much more challenging than in the case of boson stars. Different slicing conditions are explored, and a customized gauge condition that approximates polar slicing in spherical symmetry is implemented. Comparisons with 1D results and convergence tests are performed. The behavior of these stars under small axisymmetric perturbations is studied and gravitational waveforms are extracted. We find that the gravitational waves damp out on a short timescale, enabling us to obtain the complete waveform. This work is a starting point for the evolution of real scalar field systems with arbitrary symmetries. |
gr-qc/0503090 | Frans Klinkhamer | F.R. Klinkhamer, G.E. Volovik | Coexisting vacua and effective gravity | 10 pages with elsart.cls; v3: published version in Einstein issue of
PLA | Phys.Lett. A347 (2005) 8-13 | 10.1016/j.physleta.2005.05.056 | KA-TP-04-2005 | gr-qc cond-mat.stat-mech hep-ph | null | Our Universe may be a domain separated by physical phase boundaries from
other domain-Universes with different vacuum energy density and matter content.
The coexistence of different quantum vacua is perhaps regulated by the exchange
of global fermionic charges or by fermion zero modes on the phase boundary. An
example would be a static de-Sitter Universe embedded in an asymptotically flat
spacetime.
| [
{
"created": "Mon, 21 Mar 2005 16:08:35 GMT",
"version": "v1"
},
{
"created": "Tue, 19 Apr 2005 12:24:53 GMT",
"version": "v2"
},
{
"created": "Sat, 19 Nov 2005 10:56:49 GMT",
"version": "v3"
}
] | 2009-11-11 | [
[
"Klinkhamer",
"F. R.",
""
],
[
"Volovik",
"G. E.",
""
]
] | Our Universe may be a domain separated by physical phase boundaries from other domain-Universes with different vacuum energy density and matter content. The coexistence of different quantum vacua is perhaps regulated by the exchange of global fermionic charges or by fermion zero modes on the phase boundary. An example would be a static de-Sitter Universe embedded in an asymptotically flat spacetime. |
gr-qc/9611055 | Franz Embacher | Franz Embacher | Mode decomposition and unitarity in quantum cosmology, Talk given at the
Second Meeting on Constrained Dynamics and Quantum gravity, Santa Margherita
Ligure, September 17-21, 1996 | 5 pages, LaTeX (no figures) | Nucl.Phys.Proc.Suppl. 57 (1997) 291-294 | 10.1016/S0920-5632(97)00406-4 | UWThPh-1996-67 | gr-qc | null | Contrary to common belief, there are perspectives for generalizing the notion
of positive and negative frequency in minisuperspace quantum cosmology, even
when the wave equation does not admit symmetries. We outline a strategy in
doing so when the potential is positive. Also, an underlying unitarity
structure shows up. Starting in the framework of the Klein-Gordon type
quantization, I am led to a result that relies on global features on the model,
and that is possibly related to structures encountered in the refined algebraic
quantization scheme.
| [
{
"created": "Sat, 23 Nov 1996 01:46:12 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Embacher",
"Franz",
""
]
] | Contrary to common belief, there are perspectives for generalizing the notion of positive and negative frequency in minisuperspace quantum cosmology, even when the wave equation does not admit symmetries. We outline a strategy in doing so when the potential is positive. Also, an underlying unitarity structure shows up. Starting in the framework of the Klein-Gordon type quantization, I am led to a result that relies on global features on the model, and that is possibly related to structures encountered in the refined algebraic quantization scheme. |
0909.0426 | Kentarou Tanabe | Kentaro Tanabe, Norihiro Tanahashi, Tetsuya Shiromizu | On asymptotic structure at null infinity in five dimensions | 12 pages. Published version in J.Math.Phys | J.Math.Phys.51:062502,2010 | 10.1063/1.3429580 | null | gr-qc hep-th | http://creativecommons.org/licenses/publicdomain/ | We discuss the asymptotic structure of null infinity in five dimensional
space-time. Since it is known that the conformal infinity is not useful for odd
higher dimensions, we shall employ the coordinate based method like the Bondi
coordinate firstly introduced in four dimensions. Then we define the null
infinity and identify the asymptotic symmetry. We also derive the Bondi mass
expression and show its conservation law.
| [
{
"created": "Wed, 2 Sep 2009 13:38:17 GMT",
"version": "v1"
},
{
"created": "Thu, 17 Jun 2010 05:46:08 GMT",
"version": "v2"
}
] | 2010-06-18 | [
[
"Tanabe",
"Kentaro",
""
],
[
"Tanahashi",
"Norihiro",
""
],
[
"Shiromizu",
"Tetsuya",
""
]
] | We discuss the asymptotic structure of null infinity in five dimensional space-time. Since it is known that the conformal infinity is not useful for odd higher dimensions, we shall employ the coordinate based method like the Bondi coordinate firstly introduced in four dimensions. Then we define the null infinity and identify the asymptotic symmetry. We also derive the Bondi mass expression and show its conservation law. |
1005.3226 | George Gillies | Alvin J. Sanders, George T. Gillies and Ernst Schmutzer | Implications upon theory discrimination of an accurate measurement of
the time rate of change of the gravitational parameter and other cosmological
parameters | 17 pages, 3 figures Version 2 is revised as per editorial/referee
comments | Annalen Phys.522:861-873,2010 | 10.1002/andp.201010460 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A substantial improvement in the accuracy of G-dot tests (The dot denotes the
time derivative.) would make it realistic to speak in terms of a measurement of
G-dot, rather than merely a smaller upper bound on |G-dot|. We show that the
accuracy delta|G-dot/G| \approx 10^-14 yr^-1 may be sufficient, given the
accuracy of other cosmological parameters, to observe effects predicted by
higher dimensions theories and, hence, to discriminate among different models.
The \.G design goal for the SEE (Satellite Energy Exchange) mission is
delta(G-dot/G) \approx 10^-14 yr^-1.
| [
{
"created": "Tue, 18 May 2010 15:15:53 GMT",
"version": "v1"
},
{
"created": "Mon, 7 Jun 2010 18:39:07 GMT",
"version": "v2"
}
] | 2010-11-29 | [
[
"Sanders",
"Alvin J.",
""
],
[
"Gillies",
"George T.",
""
],
[
"Schmutzer",
"Ernst",
""
]
] | A substantial improvement in the accuracy of G-dot tests (The dot denotes the time derivative.) would make it realistic to speak in terms of a measurement of G-dot, rather than merely a smaller upper bound on |G-dot|. We show that the accuracy delta|G-dot/G| \approx 10^-14 yr^-1 may be sufficient, given the accuracy of other cosmological parameters, to observe effects predicted by higher dimensions theories and, hence, to discriminate among different models. The \.G design goal for the SEE (Satellite Energy Exchange) mission is delta(G-dot/G) \approx 10^-14 yr^-1. |
2406.13032 | Marcos Leopoldo Wayhs Basso | Marcos L. W. Basso and Vilson T. Zanchin | Compact regular objects from an electrified Tolman-like density: A new
interior region for the Kerr-Newman spacetime | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Charged static and rotating objects as solutions of the Einstein-Maxwell
field equations are obtained and studied in the present work. The full
spacetime geometry is obtained by matching two spacetime regions, an interior
region containing electrified matter and an exterior electrovacuum region. In
the static case, the interior region contains a spherically symmetric
distribution of matter constituted by a de Sitter-type perfect fluid with
electric charge, whose energy density profile is given by a Tolman-like
relation. The interior solution is smoothly matched with the exterior
Reissner-Nordstr\"om electrovacuum solution, thus producing different kinds of
objects, such as charged regular black holes and overcharged tension stars,
that we analyze in detail. We also investigate the connection between the
present static solution and the regular black holes with a de Sitter core
presented in the work by Lemos and Zanchin [Phys. Rev. D 83, 124005 (2011)]. We
then employ the G\"urses-G\"ursey metric and apply the Newman-Janis algorithm
to construct a charged rotating interior geometry from the static interior
solution. The resulting interior metric and the electromagnetic field are
smoothly matched to the exterior Kerr-Newman electrovacuum solution, thus
producing a regular interior for the exterior Kerr-Newman geometry. The main
properties of the complete rotating solution are analyzed in detail, showing
that different kinds of rotating objects, such as charged rotating black holes
and other charged rotating objects, also emerge in this solution.
| [
{
"created": "Tue, 18 Jun 2024 19:52:53 GMT",
"version": "v1"
}
] | 2024-06-21 | [
[
"Basso",
"Marcos L. W.",
""
],
[
"Zanchin",
"Vilson T.",
""
]
] | Charged static and rotating objects as solutions of the Einstein-Maxwell field equations are obtained and studied in the present work. The full spacetime geometry is obtained by matching two spacetime regions, an interior region containing electrified matter and an exterior electrovacuum region. In the static case, the interior region contains a spherically symmetric distribution of matter constituted by a de Sitter-type perfect fluid with electric charge, whose energy density profile is given by a Tolman-like relation. The interior solution is smoothly matched with the exterior Reissner-Nordstr\"om electrovacuum solution, thus producing different kinds of objects, such as charged regular black holes and overcharged tension stars, that we analyze in detail. We also investigate the connection between the present static solution and the regular black holes with a de Sitter core presented in the work by Lemos and Zanchin [Phys. Rev. D 83, 124005 (2011)]. We then employ the G\"urses-G\"ursey metric and apply the Newman-Janis algorithm to construct a charged rotating interior geometry from the static interior solution. The resulting interior metric and the electromagnetic field are smoothly matched to the exterior Kerr-Newman electrovacuum solution, thus producing a regular interior for the exterior Kerr-Newman geometry. The main properties of the complete rotating solution are analyzed in detail, showing that different kinds of rotating objects, such as charged rotating black holes and other charged rotating objects, also emerge in this solution. |
1306.5694 | Elena Arbuzova V. | E.V. Arbuzova, A.D. Dolgov, L. Reverberi | Spherically Symmetric Solutions in F(R) Gravity and Gravitational
Repulsion | 6 pages. References are added | Astropart.Phys. 54 (2014) 44-47 | 10.1016/j.astropartphys.2013.11.008 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Spherically symmetric solutions in F(R) theories in astronomical systems with
rising energy density are studied. The range of parameters is established for
which the flat space-time approximation for the background metric is valid. For
the solutions in which the curvature scalar oscillates with large amplitude and
high frequency, found in our previous papers, it is shown that the analysis of
the Jeans instability is strongly modified. It is discovered that for large
astronomical objects modified gravity can be repulsive, so such objects shrink
forming relatively thin shells instead of quasi uniform bodies. This may
explain the formation of cosmic voids.
| [
{
"created": "Mon, 24 Jun 2013 18:02:32 GMT",
"version": "v1"
},
{
"created": "Fri, 28 Jun 2013 11:59:22 GMT",
"version": "v2"
}
] | 2015-06-16 | [
[
"Arbuzova",
"E. V.",
""
],
[
"Dolgov",
"A. D.",
""
],
[
"Reverberi",
"L.",
""
]
] | Spherically symmetric solutions in F(R) theories in astronomical systems with rising energy density are studied. The range of parameters is established for which the flat space-time approximation for the background metric is valid. For the solutions in which the curvature scalar oscillates with large amplitude and high frequency, found in our previous papers, it is shown that the analysis of the Jeans instability is strongly modified. It is discovered that for large astronomical objects modified gravity can be repulsive, so such objects shrink forming relatively thin shells instead of quasi uniform bodies. This may explain the formation of cosmic voids. |
1404.4266 | Olivier Minazzoli | Olivier Minazzoli and Aur\'elien Hees | Late-time cosmology of scalar-tensor theories with universal
multiplicative coupling between the scalar field and the matter Lagrangian | 17 pages - accepted Phys. Rev. D | Phys. Rev. D 90, 023017, 2014 | 10.1103/PhysRevD.90.023017 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the late-time cosmological behaviour of scalar-tensor theories
with a universal multiplicative coupling between the scalar field and the
matter Lagrangian in the matter era. This class of theory encompasses the case
of the massless string dilaton (see Damour and Polyakov, General Relativity and
Gravitation, 26, 1171) as well as a theory with an intrinsic decoupling
mechanism in the solar system (see Minazzoli and Hees, Phys. Rev. D 88,
041504). The cosmological evolution is studied in the General Relativity limit
justified by solar system constraints on the gravitation theory. The behaviour
of these cosmological evolutions are then compared to two types of
observations: the constraints on temporal variations of the constants of Nature
and the distance-luminosity measurements. In particular, the non-minimal
coupling implies that the distance-luminosity relation is modified compared to
General Relativity. Theories producing a cosmological behaviour in agreement
with these observations are identified.
| [
{
"created": "Wed, 16 Apr 2014 14:33:48 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Jul 2014 08:17:30 GMT",
"version": "v2"
}
] | 2014-07-24 | [
[
"Minazzoli",
"Olivier",
""
],
[
"Hees",
"Aurélien",
""
]
] | We investigate the late-time cosmological behaviour of scalar-tensor theories with a universal multiplicative coupling between the scalar field and the matter Lagrangian in the matter era. This class of theory encompasses the case of the massless string dilaton (see Damour and Polyakov, General Relativity and Gravitation, 26, 1171) as well as a theory with an intrinsic decoupling mechanism in the solar system (see Minazzoli and Hees, Phys. Rev. D 88, 041504). The cosmological evolution is studied in the General Relativity limit justified by solar system constraints on the gravitation theory. The behaviour of these cosmological evolutions are then compared to two types of observations: the constraints on temporal variations of the constants of Nature and the distance-luminosity measurements. In particular, the non-minimal coupling implies that the distance-luminosity relation is modified compared to General Relativity. Theories producing a cosmological behaviour in agreement with these observations are identified. |
gr-qc/0105101 | Jonathan Oppenheim | Jonathan Oppenheim | Area scaling entropies for gravitating systems | 12 pages, revtex | Phys.Rev.D65:024020,2002 | 10.1103/PhysRevD.65.024020 | null | gr-qc astro-ph cond-mat.stat-mech hep-th | null | The entropy of a spherically symmetric distribution of matter in
self-equilibrium is calculated. When gravitational effects are neglected, the
entropy of the system is proportional to its volume. As effects due to
gravitational self-interactions become more important, the entropy acquires a
correction term and is no longer purely volume scaling. In the limit that the
boundary of the system approaches its event horizon, the total entropy of the
system is proportional to its area. The scaling laws of the system's
thermodynamical quantities are identical to those of a black hole, even though
the system does not possess an event horizon.
| [
{
"created": "Mon, 28 May 2001 00:57:09 GMT",
"version": "v1"
}
] | 2010-05-12 | [
[
"Oppenheim",
"Jonathan",
""
]
] | The entropy of a spherically symmetric distribution of matter in self-equilibrium is calculated. When gravitational effects are neglected, the entropy of the system is proportional to its volume. As effects due to gravitational self-interactions become more important, the entropy acquires a correction term and is no longer purely volume scaling. In the limit that the boundary of the system approaches its event horizon, the total entropy of the system is proportional to its area. The scaling laws of the system's thermodynamical quantities are identical to those of a black hole, even though the system does not possess an event horizon. |
gr-qc/0104082 | Abel Camacho Quintana | Abel Camacho (Astrophysikalisches Institut Potsdam) and Abel
Camacho-Galvan (UNAM) | Quantum nondemolition measurements of a particle in electric and
gravitational fields | Accepted in International Journal of Modern Physics D, 14 pages | Int.J.Mod.Phys. D10 (2001) 859-868 | 10.1142/S0218271801001281 | null | gr-qc quant-ph | null | In this work we obtain a nondemolition variable for the case in which a
charged particle moves in the electric and gravitational fields of a spherical
body. Afterwards we consider the continuous monitoring of this nondemolition
parameter, and calculate along the ideas of the so called restricted path
integral formalism, the corresponding propagator. Using these results the
probabilities associated with the possible measurement outputs are evaluated.
The limit of our results, as the resolution of the measuring device goes to
zero, is analyzed, and the dependence of the corresponding propagator upon the
strength of the electric and gravitational fields are commented. The role that
mass plays in the corresponding results, and its possible connection with the
equivalence principle at quantum level, are studied.
| [
{
"created": "Wed, 25 Apr 2001 17:41:40 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Camacho",
"Abel",
"",
"Astrophysikalisches Institut Potsdam"
],
[
"Camacho-Galvan",
"Abel",
"",
"UNAM"
]
] | In this work we obtain a nondemolition variable for the case in which a charged particle moves in the electric and gravitational fields of a spherical body. Afterwards we consider the continuous monitoring of this nondemolition parameter, and calculate along the ideas of the so called restricted path integral formalism, the corresponding propagator. Using these results the probabilities associated with the possible measurement outputs are evaluated. The limit of our results, as the resolution of the measuring device goes to zero, is analyzed, and the dependence of the corresponding propagator upon the strength of the electric and gravitational fields are commented. The role that mass plays in the corresponding results, and its possible connection with the equivalence principle at quantum level, are studied. |
1103.2089 | Alex Nielsen | Valerio Faraoni and Alex B. Nielsen | The horizon-entropy increase law for causal and quasi-local horizons and
conformal field redefinitions | 23 pages | null | 10.1088/0264-9381/28/17/175008 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We explicitly prove the horizon-entropy increase law for both causal and
quasi-locally defined horizons in scalar-tensor and $f(R)$ gravity theories.
Contrary to causal event horizons, future outer trapping horizons are not
conformally invariant and we provide a modification of trapping horizons to
complete the proof, using the idea of generalised entropy. This modification
means they are no longer foliated by marginally outer trapped surfaces but
fixes the location of the horizon under a conformal transformation. We also
discuss the behaviour of horizons in "veiled" general relativity and show,
using this new definition, how to locate cosmological horizons in flat
Minkowski space with varying units, which is physically identified with a
spatially flat FLRW spacetime.
| [
{
"created": "Thu, 10 Mar 2011 17:46:19 GMT",
"version": "v1"
}
] | 2015-05-27 | [
[
"Faraoni",
"Valerio",
""
],
[
"Nielsen",
"Alex B.",
""
]
] | We explicitly prove the horizon-entropy increase law for both causal and quasi-locally defined horizons in scalar-tensor and $f(R)$ gravity theories. Contrary to causal event horizons, future outer trapping horizons are not conformally invariant and we provide a modification of trapping horizons to complete the proof, using the idea of generalised entropy. This modification means they are no longer foliated by marginally outer trapped surfaces but fixes the location of the horizon under a conformal transformation. We also discuss the behaviour of horizons in "veiled" general relativity and show, using this new definition, how to locate cosmological horizons in flat Minkowski space with varying units, which is physically identified with a spatially flat FLRW spacetime. |
1503.02162 | Anton Galajinsky | Marco Cariglia and Anton Galajinsky | Ricci-flat spacetimes admitting higher rank Killing tensors | 12 pages | null | 10.1016/j.physletb.2015.04.001 | null | gr-qc hep-th math-ph math.MP nlin.SI | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Ricci-flat spacetimes of signature (2,q) with q=2,3,4 are constructed which
admit irreducible Killing tensors of rank-3 or rank-4. The construction relies
upon the Eisenhart lift applied to Drach's two-dimensional integrable systems
which is followed by the oxidation with respect to free parameters. In four
dimensions, some of our solutions are anti-self-dual.
| [
{
"created": "Sat, 7 Mar 2015 11:46:59 GMT",
"version": "v1"
}
] | 2015-05-20 | [
[
"Cariglia",
"Marco",
""
],
[
"Galajinsky",
"Anton",
""
]
] | Ricci-flat spacetimes of signature (2,q) with q=2,3,4 are constructed which admit irreducible Killing tensors of rank-3 or rank-4. The construction relies upon the Eisenhart lift applied to Drach's two-dimensional integrable systems which is followed by the oxidation with respect to free parameters. In four dimensions, some of our solutions are anti-self-dual. |
gr-qc/9812040 | Ken D. Olum | Ken D. Olum and J. J. Blanco-Pillado | Field theory simulation of Abelian-Higgs cosmic string cusps | 9 pages, RevTeX, 13 figures with epsf | Phys.Rev. D60 (1999) 023503 | 10.1103/PhysRevD.60.023503 | null | gr-qc astro-ph hep-ph | null | We have performed a lattice field theory simulation of cusps in Abelian-Higgs
cosmic strings. The results are in accord with the theory that the portion of
the strings which overlaps near the cusp is released as radiation. The radius
of the string cores which must touch to produce the evaporation is
approximately $r = 1$ in natural units. In general, the modifications to the
string shape due to the cusp may produce many cusps later in the evolution of a
string loop, but these later cusps will be much smaller in magnitude and more
closely resemble kinks.
| [
{
"created": "Fri, 11 Dec 1998 22:46:28 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Olum",
"Ken D.",
""
],
[
"Blanco-Pillado",
"J. J.",
""
]
] | We have performed a lattice field theory simulation of cusps in Abelian-Higgs cosmic strings. The results are in accord with the theory that the portion of the strings which overlaps near the cusp is released as radiation. The radius of the string cores which must touch to produce the evaporation is approximately $r = 1$ in natural units. In general, the modifications to the string shape due to the cusp may produce many cusps later in the evolution of a string loop, but these later cusps will be much smaller in magnitude and more closely resemble kinks. |
2304.03067 | Celia Escamilla-Rivera | Geovanny A. Rave-Franco, Celia Escamilla-Rivera and Jackson Levi Said | Production of Primordial Gravitational Waves in Teleparallel Gravity | 21 pages. Version accepted in Physics of the Dark Universe | Physics of the Dark Universe 2023 | 10.1016/j.dark.2023.101316 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We study the production of primordial gravitational waves in the context of
extended teleparallel gravity models and compare them with those of general
relativity. Teleparallel gravity has been widely studied in the context of the
late universe but not much in the early universe. Two sources of primordial
gravitational waves are considered, vacuum fluctuations and tensor anisotropies
within two inflation-compatible backgrounds: a perfect de Sitter and a quasi de
Sitter background. We find that in the vacuum case with a perfect de Sitter
background, the gravitational waves propagation equation is the same as that of
general relativity, however, if the background is promoted to a quasi de Sitter
background, the propagation equations are different resulting in an important
difference on the tensor spectral index. When tensor anisotropies are included,
we compute the most general solution for gravitational waves in terms of a
retarded Green's function and analyze the contributions to the power spectrum
from these anisotropies. Finally, we investigate the energy density of these
gravitational waves.
| [
{
"created": "Thu, 6 Apr 2023 13:32:19 GMT",
"version": "v1"
},
{
"created": "Wed, 16 Aug 2023 20:35:16 GMT",
"version": "v2"
}
] | 2023-08-29 | [
[
"Rave-Franco",
"Geovanny A.",
""
],
[
"Escamilla-Rivera",
"Celia",
""
],
[
"Said",
"Jackson Levi",
""
]
] | We study the production of primordial gravitational waves in the context of extended teleparallel gravity models and compare them with those of general relativity. Teleparallel gravity has been widely studied in the context of the late universe but not much in the early universe. Two sources of primordial gravitational waves are considered, vacuum fluctuations and tensor anisotropies within two inflation-compatible backgrounds: a perfect de Sitter and a quasi de Sitter background. We find that in the vacuum case with a perfect de Sitter background, the gravitational waves propagation equation is the same as that of general relativity, however, if the background is promoted to a quasi de Sitter background, the propagation equations are different resulting in an important difference on the tensor spectral index. When tensor anisotropies are included, we compute the most general solution for gravitational waves in terms of a retarded Green's function and analyze the contributions to the power spectrum from these anisotropies. Finally, we investigate the energy density of these gravitational waves. |
2308.10605 | Anshuman Baruah | Parangam Goswami, Anshuman Baruah, Atri Deshamukhya | Traversable wormholes in $f(R)$ gravity sourced by a cloud of strings | null | East European Journal of Physics 1. 112-126 (2024) | 10.26565/2312-4334-2024-1-09 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Wormhole solutions in General Relativity (GR) require \textit{exotic} matter
sources that violate the null energy condition (NEC), and it is well known that
higher-order modifications of GR and some alternative matter sources can
support wormholes. In this study, we explore the possibility of formulating
traversable wormholes in $f(R)$ modified gravity, which is perhaps the most
widely discussed modification of GR, with two approaches. First, to investigate
the effects of geometrical constraints on the global characteristics, we gauge
the $rr$-component of the metric tensor, and employ Pad\`{e} approximation to
check whether a well-constrained \textit{shape function} can be formulated in
this manner. We then derive the field equations with a background of string
cloud, and numerically analyse the energy conditions, stability, and amount of
exotic matter in this space-time. Next, as an alternative source in a simple
$f(R)$ gravity model, we use the background cloud of strings to estimate the
wormhole shape function, and analyse the relevant properties of the space-time.
These results are then compared with those of wormholes threaded by normal
matter in the simple $f(R)$ gravity model considered. The results demonstrate
that wormholes with NEC violations are feasible; however, the wormhole
space-times in the simple $f(R)$ gravity model are unstable.
| [
{
"created": "Mon, 21 Aug 2023 10:02:31 GMT",
"version": "v1"
}
] | 2024-03-06 | [
[
"Goswami",
"Parangam",
""
],
[
"Baruah",
"Anshuman",
""
],
[
"Deshamukhya",
"Atri",
""
]
] | Wormhole solutions in General Relativity (GR) require \textit{exotic} matter sources that violate the null energy condition (NEC), and it is well known that higher-order modifications of GR and some alternative matter sources can support wormholes. In this study, we explore the possibility of formulating traversable wormholes in $f(R)$ modified gravity, which is perhaps the most widely discussed modification of GR, with two approaches. First, to investigate the effects of geometrical constraints on the global characteristics, we gauge the $rr$-component of the metric tensor, and employ Pad\`{e} approximation to check whether a well-constrained \textit{shape function} can be formulated in this manner. We then derive the field equations with a background of string cloud, and numerically analyse the energy conditions, stability, and amount of exotic matter in this space-time. Next, as an alternative source in a simple $f(R)$ gravity model, we use the background cloud of strings to estimate the wormhole shape function, and analyse the relevant properties of the space-time. These results are then compared with those of wormholes threaded by normal matter in the simple $f(R)$ gravity model considered. The results demonstrate that wormholes with NEC violations are feasible; however, the wormhole space-times in the simple $f(R)$ gravity model are unstable. |
1810.02178 | Vojtech Pravda | Martin Kuchynka, Tom\'a\v{s} M\'alek, Vojt\v{e}ch Pravda, Alena
Pravdov\'a | Almost universal spacetimes in higher-order gravity theories | 17 pages, final version, to appear in Phys. Rev. D | Phys. Rev. D 99, 024043 (2019) | 10.1103/PhysRevD.99.024043 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study almost universal spacetimes - spacetimes for which the field
equations of any generalized gravity with the Lagrangian constructed from the
metric, the Riemann tensor and its covariant derivatives of arbitrary order
reduce to one single differential equation and one algebraic condition for the
Ricci scalar. We prove that all d-dimensional Kundt spacetimes of Weyl type III
and traceless Ricci type N are almost universal. Explicit examples of Weyl type
II almost universal Kundt metrics are also given. The considerable
simplification of the field equations of higher-order gravity theories for
almost universal spacetimes is then employed to study new Weyl type II, III,
and N vacuum solutions to quadratic gravity in arbitrary dimension and
six-dimensional conformal gravity. Necessary conditions for almost universal
metrics are also studied.
| [
{
"created": "Thu, 4 Oct 2018 12:51:55 GMT",
"version": "v1"
},
{
"created": "Wed, 2 Jan 2019 11:13:37 GMT",
"version": "v2"
}
] | 2019-02-05 | [
[
"Kuchynka",
"Martin",
""
],
[
"Málek",
"Tomáš",
""
],
[
"Pravda",
"Vojtěch",
""
],
[
"Pravdová",
"Alena",
""
]
] | We study almost universal spacetimes - spacetimes for which the field equations of any generalized gravity with the Lagrangian constructed from the metric, the Riemann tensor and its covariant derivatives of arbitrary order reduce to one single differential equation and one algebraic condition for the Ricci scalar. We prove that all d-dimensional Kundt spacetimes of Weyl type III and traceless Ricci type N are almost universal. Explicit examples of Weyl type II almost universal Kundt metrics are also given. The considerable simplification of the field equations of higher-order gravity theories for almost universal spacetimes is then employed to study new Weyl type II, III, and N vacuum solutions to quadratic gravity in arbitrary dimension and six-dimensional conformal gravity. Necessary conditions for almost universal metrics are also studied. |
1310.4795 | Brajesh Gupt | Peter Diener, Brajesh Gupt, Parampreet Singh | Chimera: A hybrid approach to numerical loop quantum cosmology | Minor revision to match published version. To appear in CQG | Class.Quant.Grav. 31 (2014) 025013 | 10.1088/0264-9381/31/2/025013 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The existence of a quantum bounce in isotropic spacetimes is a key result in
loop quantum cosmology (LQC), which has been demonstrated to arise in all the
models studied so far. In most of the models, the bounce has been studied using
numerical simulations involving states which are sharply peaked and which
bounce at volumes much larger than the Planck volume. An important issue is to
confirm the existence of the bounce for states which have a wide spread, or
which bounce closer to the Planck volume. Numerical simulations with such
states demand large computational domains, making them very expensive and
practically infeasible with the techniques which have been implemented so far.
To overcome these difficulties, we present an efficient hybrid numerical scheme
using the property that at the small spacetime curvature, the quantum
Hamiltonian constraint in LQC, which is a difference equation with uniform
discretization in volume, can be approximated by a Wheeler-DeWitt differential
equation. By carefully choosing a hybrid spatial grid allowing the use of
partial differential equations at large volumes, and with a simple change of
geometrical coordinate, we obtain a surprising reduction in the computational
cost. This scheme enables us to explore regimes which were so far unachievable
for the isotropic model in LQC. Our approach also promises to significantly
reduce the computational cost for numerical simulations in anisotropic LQC
using high performance computing.
| [
{
"created": "Thu, 17 Oct 2013 18:46:20 GMT",
"version": "v1"
},
{
"created": "Tue, 12 Nov 2013 18:51:40 GMT",
"version": "v2"
}
] | 2017-06-20 | [
[
"Diener",
"Peter",
""
],
[
"Gupt",
"Brajesh",
""
],
[
"Singh",
"Parampreet",
""
]
] | The existence of a quantum bounce in isotropic spacetimes is a key result in loop quantum cosmology (LQC), which has been demonstrated to arise in all the models studied so far. In most of the models, the bounce has been studied using numerical simulations involving states which are sharply peaked and which bounce at volumes much larger than the Planck volume. An important issue is to confirm the existence of the bounce for states which have a wide spread, or which bounce closer to the Planck volume. Numerical simulations with such states demand large computational domains, making them very expensive and practically infeasible with the techniques which have been implemented so far. To overcome these difficulties, we present an efficient hybrid numerical scheme using the property that at the small spacetime curvature, the quantum Hamiltonian constraint in LQC, which is a difference equation with uniform discretization in volume, can be approximated by a Wheeler-DeWitt differential equation. By carefully choosing a hybrid spatial grid allowing the use of partial differential equations at large volumes, and with a simple change of geometrical coordinate, we obtain a surprising reduction in the computational cost. This scheme enables us to explore regimes which were so far unachievable for the isotropic model in LQC. Our approach also promises to significantly reduce the computational cost for numerical simulations in anisotropic LQC using high performance computing. |
1906.06644 | Hamed Pejhan | Hamed Pejhan, Mohammad Enayati, Jean-Pierre Gazeau, and Anzhong Wang | Gupta-Bleuler quantization for linearized gravity in de Sitter spacetime | 19 pages, no figure, version accepted for publication in Physical
Review D | Phys. Rev. D 100, 066012 (2019) | 10.1103/PhysRevD.100.066012 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In a recent Letter, we have pointed out that the linearized Einstein gravity
in de Sitter (dS) spacetime besides the spacetime symmetries generated by the
Killing vectors and the evident gauge symmetry also possesses a hitherto
`hidden' local (gauge-like) symmetry which becomes anomalous on the quantum
level. This gauge-like anomaly makes the theory inconsistent and must be
canceled at all costs. In this companion paper, we first review our argument
and discuss it in more detail. We argue that the cancelation of this anomaly
makes it impossible to preserve dS symmetry in linearized quantum gravity
through the usual canonical quantization in a consistent manner. Then,
demanding that all the classical symmetries to survive in the quantized theory,
we set up a coordinate-independent formalism \`{a} \emph{la} Gupta-Bleuler
which allows for preserving the (manifest) dS covariance in the presence of the
gauge and the gauge-like invariance of the theory. On this basis, considering a
new representation of the canonical commutation relations, we present a
graviton quantum field on dS space, transforming correctly under isometries,
gauge transformations, and gauge-like transformations, which acts on a state
space containing a vacuum invariant under all of them. Despite the appearance
of negative norm states in this quantization scheme, the energy operator is
positive in all physical states, and vanishes in the vacuum.
| [
{
"created": "Sun, 16 Jun 2019 04:00:39 GMT",
"version": "v1"
},
{
"created": "Tue, 20 Aug 2019 01:29:19 GMT",
"version": "v2"
}
] | 2019-09-12 | [
[
"Pejhan",
"Hamed",
""
],
[
"Enayati",
"Mohammad",
""
],
[
"Gazeau",
"Jean-Pierre",
""
],
[
"Wang",
"Anzhong",
""
]
] | In a recent Letter, we have pointed out that the linearized Einstein gravity in de Sitter (dS) spacetime besides the spacetime symmetries generated by the Killing vectors and the evident gauge symmetry also possesses a hitherto `hidden' local (gauge-like) symmetry which becomes anomalous on the quantum level. This gauge-like anomaly makes the theory inconsistent and must be canceled at all costs. In this companion paper, we first review our argument and discuss it in more detail. We argue that the cancelation of this anomaly makes it impossible to preserve dS symmetry in linearized quantum gravity through the usual canonical quantization in a consistent manner. Then, demanding that all the classical symmetries to survive in the quantized theory, we set up a coordinate-independent formalism \`{a} \emph{la} Gupta-Bleuler which allows for preserving the (manifest) dS covariance in the presence of the gauge and the gauge-like invariance of the theory. On this basis, considering a new representation of the canonical commutation relations, we present a graviton quantum field on dS space, transforming correctly under isometries, gauge transformations, and gauge-like transformations, which acts on a state space containing a vacuum invariant under all of them. Despite the appearance of negative norm states in this quantization scheme, the energy operator is positive in all physical states, and vanishes in the vacuum. |
1306.4487 | Miquel Nofrarias | M Nofrarias, F Antonucci, M Armano, H Audley, G Auger, M Benedetti, P
Binetruy, J Bogenstahl, D Bortoluzzi, N Brandt, M Caleno, A Cavalleri, G
Congedo, M Cruise, K Danzmann, F De Marchi, M Diaz-Aguilo, I Diepholz, G
Dixon, R Dolesi, N Dunbar, J Fauste, L Ferraioli, V Ferroni W Fichter, E
Fitzsimons, M Freschi, C Garc\'ia Marirrodriga, R Gerndt, L Gesa, F Gibert, D
Giardini, C Grimani, A Grynagier, F Guzm\'an, I Harrison, G Heinzel, M
Hewitson, D Hollington, D Hoyland, M Hueller, J Huesler, O Jennrich, P
Jetzer, B Johlander, N Karnesis, N Korsakova, C Killow, X Llamas, I Lloro, A
Lobo, R Maarschalkerweerd, S Madden, D Mance, I Mateos, P W McNamara, J
Mendes, E Mitchell, D Nicolini, D Nicolodi, M Perreur-Lloyd, E Plagnol, P
Prat, J Ramos-Castro, J Reiche, J A Romera Perez, D Robertson, H Rozemeijer,
G Russano, A Schleicher, D Shaul, CF Sopuerta, T J Sumner, A Taylor, D
Texier, C Trenkel, H-B Tu, S Vitale, G Wanner, H Ward, S Waschke, P Wass, D
Wealthy, S Wen, W J Weber, T Ziegler, P Zweifel | State space modelling and data analysis exercises in LISA Pathfinder | Plenary talk presented at the 9th International LISA Symposium, 21-25
May 2012, Paris | 2013ASPC..467..161N | null | null | gr-qc astro-ph.IM physics.data-an physics.ins-det | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | LISA Pathfinder is a mission planned by the European Space Agency to test the
key technologies that will allow the detection of gravitational waves in space.
The instrument on-board, the LISA Technology package, will undergo an
exhaustive campaign of calibrations and noise characterisation campaigns in
order to fully describe the noise model. Data analysis plays an important role
in the mission and for that reason the data analysis team has been developing a
toolbox which contains all the functionalities required during operations. In
this contribution we give an overview of recent activities, focusing on the
improvements in the modelling of the instrument and in the data analysis
campaigns performed both with real and simulated data.
| [
{
"created": "Wed, 19 Jun 2013 10:56:24 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Jun 2013 10:02:32 GMT",
"version": "v2"
}
] | 2013-06-24 | [
[
"Nofrarias",
"M",
""
],
[
"Antonucci",
"F",
""
],
[
"Armano",
"M",
""
],
[
"Audley",
"H",
""
],
[
"Auger",
"G",
""
],
[
"Benedetti",
"M",
""
],
[
"Binetruy",
"P",
""
],
[
"Bogenstahl",
"J",
""
],
[
"Bortoluzzi",
"D",
""
],
[
"Brandt",
"N",
""
],
[
"Caleno",
"M",
""
],
[
"Cavalleri",
"A",
""
],
[
"Congedo",
"G",
""
],
[
"Cruise",
"M",
""
],
[
"Danzmann",
"K",
""
],
[
"De Marchi",
"F",
""
],
[
"Diaz-Aguilo",
"M",
""
],
[
"Diepholz",
"I",
""
],
[
"Dixon",
"G",
""
],
[
"Dolesi",
"R",
""
],
[
"Dunbar",
"N",
""
],
[
"Fauste",
"J",
""
],
[
"Ferraioli",
"L",
""
],
[
"Fichter",
"V Ferroni W",
""
],
[
"Fitzsimons",
"E",
""
],
[
"Freschi",
"M",
""
],
[
"Marirrodriga",
"C García",
""
],
[
"Gerndt",
"R",
""
],
[
"Gesa",
"L",
""
],
[
"Gibert",
"F",
""
],
[
"Giardini",
"D",
""
],
[
"Grimani",
"C",
""
],
[
"Grynagier",
"A",
""
],
[
"Guzmán",
"F",
""
],
[
"Harrison",
"I",
""
],
[
"Heinzel",
"G",
""
],
[
"Hewitson",
"M",
""
],
[
"Hollington",
"D",
""
],
[
"Hoyland",
"D",
""
],
[
"Hueller",
"M",
""
],
[
"Huesler",
"J",
""
],
[
"Jennrich",
"O",
""
],
[
"Jetzer",
"P",
""
],
[
"Johlander",
"B",
""
],
[
"Karnesis",
"N",
""
],
[
"Korsakova",
"N",
""
],
[
"Killow",
"C",
""
],
[
"Llamas",
"X",
""
],
[
"Lloro",
"I",
""
],
[
"Lobo",
"A",
""
],
[
"Maarschalkerweerd",
"R",
""
],
[
"Madden",
"S",
""
],
[
"Mance",
"D",
""
],
[
"Mateos",
"I",
""
],
[
"McNamara",
"P W",
""
],
[
"Mendes",
"J",
""
],
[
"Mitchell",
"E",
""
],
[
"Nicolini",
"D",
""
],
[
"Nicolodi",
"D",
""
],
[
"Perreur-Lloyd",
"M",
""
],
[
"Plagnol",
"E",
""
],
[
"Prat",
"P",
""
],
[
"Ramos-Castro",
"J",
""
],
[
"Reiche",
"J",
""
],
[
"Perez",
"J A Romera",
""
],
[
"Robertson",
"D",
""
],
[
"Rozemeijer",
"H",
""
],
[
"Russano",
"G",
""
],
[
"Schleicher",
"A",
""
],
[
"Shaul",
"D",
""
],
[
"Sopuerta",
"CF",
""
],
[
"Sumner",
"T J",
""
],
[
"Taylor",
"A",
""
],
[
"Texier",
"D",
""
],
[
"Trenkel",
"C",
""
],
[
"Tu",
"H-B",
""
],
[
"Vitale",
"S",
""
],
[
"Wanner",
"G",
""
],
[
"Ward",
"H",
""
],
[
"Waschke",
"S",
""
],
[
"Wass",
"P",
""
],
[
"Wealthy",
"D",
""
],
[
"Wen",
"S",
""
],
[
"Weber",
"W J",
""
],
[
"Ziegler",
"T",
""
],
[
"Zweifel",
"P",
""
]
] | LISA Pathfinder is a mission planned by the European Space Agency to test the key technologies that will allow the detection of gravitational waves in space. The instrument on-board, the LISA Technology package, will undergo an exhaustive campaign of calibrations and noise characterisation campaigns in order to fully describe the noise model. Data analysis plays an important role in the mission and for that reason the data analysis team has been developing a toolbox which contains all the functionalities required during operations. In this contribution we give an overview of recent activities, focusing on the improvements in the modelling of the instrument and in the data analysis campaigns performed both with real and simulated data. |
1606.00147 | Kazuharu Bamba | Z. Yousaf, Kazuharu Bamba and M. Zaeem ul Haq Bhatti | Causes of Irregular Energy Density in $f(R,T)$ Gravity | 25 pages, no figure, version accepted for publication in Physical
Review D | Phys. Rev. D 93, 124048 (2016) | 10.1103/PhysRevD.93.124048 | FU-PCG-12 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate irregularity factors for a self-gravitating spherical star
evolving in the presence of imperfect fluid. We explore the gravitational field
equations and the dynamical equations with the systematic construction in
$f(R,T)$ gravity, where $T$ is the trace of the energy-momentum tensor.
Furthermore, we analyze two well-known differential equations (which occupy
principal importance in the exploration of causes of energy density
inhomogeneities) with the help of the Weyl tensor and the conservation laws.
The irregularity factors for a spherical star are examined for particular cases
of dust, isotropic and anisotropic fluids in dissipative and non-dissipative
regimes in the framework of $f(R,T)$ gravity. It is found that as the
complexity in the matter with the anisotropic stresses increases, the
inhomogeneity factor has more correspondences to one of the structure scalars.
| [
{
"created": "Wed, 1 Jun 2016 07:37:05 GMT",
"version": "v1"
}
] | 2016-06-29 | [
[
"Yousaf",
"Z.",
""
],
[
"Bamba",
"Kazuharu",
""
],
[
"Bhatti",
"M. Zaeem ul Haq",
""
]
] | We investigate irregularity factors for a self-gravitating spherical star evolving in the presence of imperfect fluid. We explore the gravitational field equations and the dynamical equations with the systematic construction in $f(R,T)$ gravity, where $T$ is the trace of the energy-momentum tensor. Furthermore, we analyze two well-known differential equations (which occupy principal importance in the exploration of causes of energy density inhomogeneities) with the help of the Weyl tensor and the conservation laws. The irregularity factors for a spherical star are examined for particular cases of dust, isotropic and anisotropic fluids in dissipative and non-dissipative regimes in the framework of $f(R,T)$ gravity. It is found that as the complexity in the matter with the anisotropic stresses increases, the inhomogeneity factor has more correspondences to one of the structure scalars. |
1411.7850 | T\'erence Delsate | Terence Delsate and Robert Mann | Van Der Waals Black Holes in $d$ dimensions | 14 p., 4 figures | null | 10.1007/JHEP02(2015)070 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We generalize the recent solution proposed by Rajagopal et al. to arbitrary
number of dimensions and horizon topologies. We comment on the regime of
validity of these solution. Among our main results, we argue that the Van Der
Waals (VDW) black hole (BH) metric is to be interpreted as a near horizon
metric. This is supported by inspecting the energy conditions. We analyze the
limiting cases of a perfect fluid, interacting points and non interacting balls
gas equation of state and map them to known black holes. Finally, we provide a
case study by comparing the Reissner-Nordstr\"om and VDW BH close to the
horizon and show that they are qualitatively similar for some range of the
horizon radius.
| [
{
"created": "Fri, 28 Nov 2014 13:12:46 GMT",
"version": "v1"
}
] | 2015-06-23 | [
[
"Delsate",
"Terence",
""
],
[
"Mann",
"Robert",
""
]
] | We generalize the recent solution proposed by Rajagopal et al. to arbitrary number of dimensions and horizon topologies. We comment on the regime of validity of these solution. Among our main results, we argue that the Van Der Waals (VDW) black hole (BH) metric is to be interpreted as a near horizon metric. This is supported by inspecting the energy conditions. We analyze the limiting cases of a perfect fluid, interacting points and non interacting balls gas equation of state and map them to known black holes. Finally, we provide a case study by comparing the Reissner-Nordstr\"om and VDW BH close to the horizon and show that they are qualitatively similar for some range of the horizon radius. |
1802.00687 | Nicola Rendell | Nicola Rendell | Large-distance behaviour of the massless vector two-point function in de
Sitter spacetime | 14 pages, no figures, to appear in a Special Issue of the IJMPD on
Selected Papers of the III Amazonian Symposium on Physics | null | 10.1142/S0218271818430058 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the long-distance behaviour of the massless vector propagator in
(n)-dimensional de Sitter spacetime, where $n \geq 4$. Specifically, we
consider the massless limit of the vector propagator in the Stueckelberg
theory, which is an extension of Proca theory, with an additional gauge-fixing
term. We work to leading order in the de Sitter-invariant distance $Z$ to show
that, in the large $Z$ limit, this propagator tends to a gauge dependent
constant, where the gauge worked in is described by the Stueckelberg parameter
$\xi$. In the Landau gauge, where $\xi=0$, this constant is found to be 0. This
result is in agreement with the 4 dimensional case discussed by Youssef.
| [
{
"created": "Fri, 2 Feb 2018 14:07:04 GMT",
"version": "v1"
},
{
"created": "Thu, 3 May 2018 11:18:05 GMT",
"version": "v2"
}
] | 2018-05-04 | [
[
"Rendell",
"Nicola",
""
]
] | We study the long-distance behaviour of the massless vector propagator in (n)-dimensional de Sitter spacetime, where $n \geq 4$. Specifically, we consider the massless limit of the vector propagator in the Stueckelberg theory, which is an extension of Proca theory, with an additional gauge-fixing term. We work to leading order in the de Sitter-invariant distance $Z$ to show that, in the large $Z$ limit, this propagator tends to a gauge dependent constant, where the gauge worked in is described by the Stueckelberg parameter $\xi$. In the Landau gauge, where $\xi=0$, this constant is found to be 0. This result is in agreement with the 4 dimensional case discussed by Youssef. |
2304.09777 | Grigoris Panotopoulos | L. Balart, S. Belmar-Herrera, G. Panotopoulos, \'A. Rinc\'on | Novel charged black hole solutions of Born-Infeld type: General
properties, Smarr formula and Quasinormal frequencies | 18 pages, 7 figures, 3 tables, to be published in Annals of Physics | null | 10.1016/j.aop.2023.169329 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate two novel models of charged black holes in the framework of
non-linear electrodynamics of Born-Infeld type. In particular, starting from
two concrete Lagrangian densities, the corresponding metric potentials, the
electric field, the Smarr formula and finally, the (scalar) quasinormal modes
are computed for each model. Our findings show that although the models look
very similar, their quasinormal spectra are characterized by certain
differences.
| [
{
"created": "Wed, 19 Apr 2023 16:00:35 GMT",
"version": "v1"
}
] | 2023-05-31 | [
[
"Balart",
"L.",
""
],
[
"Belmar-Herrera",
"S.",
""
],
[
"Panotopoulos",
"G.",
""
],
[
"Rincón",
"Á.",
""
]
] | We investigate two novel models of charged black holes in the framework of non-linear electrodynamics of Born-Infeld type. In particular, starting from two concrete Lagrangian densities, the corresponding metric potentials, the electric field, the Smarr formula and finally, the (scalar) quasinormal modes are computed for each model. Our findings show that although the models look very similar, their quasinormal spectra are characterized by certain differences. |
0810.5119 | Martin Bojowald | Martin Bojowald and Juan D. Reyes | Dilaton Gravity, Poisson Sigma Models and Loop Quantum Gravity | 31 pages | Class.Quant.Grav.26:035018,2009 | 10.1088/0264-9381/26/3/035018 | IGC-08/10-2 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Spherically symmetric gravity in Ashtekar variables coupled to Yang-Mills
theory in two dimensions and its relation to dilaton gravity and Poisson sigma
models are discussed. After introducing its loop quantization, quantum
corrections for inverse triad components are shown to provide a consistent
deformation without anomalies. The relation to Poisson sigma models provides a
covariant action principle of the quantum corrected theory with effective
couplings. Results are also used to provide loop quantizations of spherically
symmetric models in arbitrary D space-time dimensions.
| [
{
"created": "Tue, 28 Oct 2008 19:46:20 GMT",
"version": "v1"
}
] | 2009-02-06 | [
[
"Bojowald",
"Martin",
""
],
[
"Reyes",
"Juan D.",
""
]
] | Spherically symmetric gravity in Ashtekar variables coupled to Yang-Mills theory in two dimensions and its relation to dilaton gravity and Poisson sigma models are discussed. After introducing its loop quantization, quantum corrections for inverse triad components are shown to provide a consistent deformation without anomalies. The relation to Poisson sigma models provides a covariant action principle of the quantum corrected theory with effective couplings. Results are also used to provide loop quantizations of spherically symmetric models in arbitrary D space-time dimensions. |
2203.12002 | Barun Kumar Pal | Barun Kumar Pal | An Inflationary Equation of State | null | IJMPD, 2023 | 10.1142/S0218271823500190 | Volume No. 32, Issue No. 04, Article No. 2350019, Year 2023 | gr-qc hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We have studied inflationary paradigm through an inflationary equation of
state. With a single parameter equation of state as a function of the scalar
field responsible for accelerated expansion, we find an observationally viable
model satisfying all the constraints as laid down by the recent observations.
The resulting model can efficiently cover a wide range of tensor-to-scalar
ratio ranging from $r\sim\mathcal{O}(10^{-1})$ to $\mathcal{O}(10^{-6})$, other
inflationary observables being consistent with the latest data. Nowadays
ultimate eliminator between inflationary models is the tensor-to-scalar ratio,
the model presented here is capable of keeping up with the future probes of
tensor-to-scalar ratio at the same time having good agreement with other
inflationary observables.
| [
{
"created": "Tue, 22 Mar 2022 19:11:48 GMT",
"version": "v1"
}
] | 2023-05-10 | [
[
"Pal",
"Barun Kumar",
""
]
] | We have studied inflationary paradigm through an inflationary equation of state. With a single parameter equation of state as a function of the scalar field responsible for accelerated expansion, we find an observationally viable model satisfying all the constraints as laid down by the recent observations. The resulting model can efficiently cover a wide range of tensor-to-scalar ratio ranging from $r\sim\mathcal{O}(10^{-1})$ to $\mathcal{O}(10^{-6})$, other inflationary observables being consistent with the latest data. Nowadays ultimate eliminator between inflationary models is the tensor-to-scalar ratio, the model presented here is capable of keeping up with the future probes of tensor-to-scalar ratio at the same time having good agreement with other inflationary observables. |
gr-qc/0306080 | Claudio Benedito Silva Furtado | A. M. de M. Carvalho, Fernando Moraes, Claudio Furtado | Loop variables in the geometry of a rotating black string | 14 pages, iopart style | Class.Quant.Grav. 20 (2003) 2063-2074 | 10.1088/0264-9381/20/11/308 | null | gr-qc | null | In this paper we analyze in the Wilson loop context the parallel transport of
vectors and spinors around a closed loop in the background space-time of a
rotating black string in order to classify its global properties. We also
examine particular closed orbits in this space-time and verify the Mandelstam
relations.
| [
{
"created": "Tue, 17 Jun 2003 20:04:48 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Carvalho",
"A. M. de M.",
""
],
[
"Moraes",
"Fernando",
""
],
[
"Furtado",
"Claudio",
""
]
] | In this paper we analyze in the Wilson loop context the parallel transport of vectors and spinors around a closed loop in the background space-time of a rotating black string in order to classify its global properties. We also examine particular closed orbits in this space-time and verify the Mandelstam relations. |
gr-qc/0609070 | Shabbir Ghulam | Ghulam Shabbir, Shaukat Iqbal | Proper Conformal Vector fields in Bianchi Type I Space-Times | 5 pages | null | null | null | gr-qc | null | Direct integration technique is used to study the proper conformal vector
fields in non conformally flat Bianchi type-1 space-times. Using the above
mentioned technique we have shown that a very special class of the above
space-time admits proper conformal vector fields.
| [
{
"created": "Tue, 19 Sep 2006 04:08:13 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Shabbir",
"Ghulam",
""
],
[
"Iqbal",
"Shaukat",
""
]
] | Direct integration technique is used to study the proper conformal vector fields in non conformally flat Bianchi type-1 space-times. Using the above mentioned technique we have shown that a very special class of the above space-time admits proper conformal vector fields. |
1103.3553 | Hossein Farajollahi | H. Farajollahi and F. Milani | Stability analysis in Modified Non-Local Gravity | 12 pages, 4 figures, will be published in Int. J. Theor. Phys | Int. J. Theor. Phys. 50, 6, 1953-1961, 2011 | 10.1007/s10773-011-0710-5 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we consider FRW cosmology in modified non-local gravity. The
stability analysis shows that there is only one stable critical point for the
model and the universe undergoes a quintessence dominated era.
| [
{
"created": "Fri, 18 Mar 2011 04:54:50 GMT",
"version": "v1"
}
] | 2011-06-09 | [
[
"Farajollahi",
"H.",
""
],
[
"Milani",
"F.",
""
]
] | In this paper we consider FRW cosmology in modified non-local gravity. The stability analysis shows that there is only one stable critical point for the model and the universe undergoes a quintessence dominated era. |
gr-qc/0703095 | Jorge Ovalle | J Ovalle | Searching Exact Solutions for Compact Stars in Braneworld: a conjecture | 24 pages; a new section with a regular solution; to appear in Modern
Phys. Lett. A | Mod.Phys.Lett.A23:3247-3263,2008 | 10.1142/S0217732308027011 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the context of the braneworld, a method to find consistent solutions to
Einstein's field equations in the interior of a spherically symmetric, static
and non uniform stellar distribution with Weyl stresses is developed. This
method, based in the fact that any braneworld stellar solution must have the
general relativity solution as a limit, produces a constraint which reduces the
degrees of freedom on the brane. Hence the non locality and non closure of the
braneworld equations can be overcome. The constraint found is physically
interpreted as a necessary condition to regain general relativity, and a
particular solution for it is used to find an exact and physically acceptable
analytical internal solution to no-uniform stellar distributions on the brane.
It is shown that such an exact solution is possible due to the fact that bulk
corrections to pressure, density and a metric component are a null source of
anisotropic effects on the brane. A conjecture is proposed about the
possibility of finding physically relevant exact solutions to non-uniform
stellar distributions on the brane.
| [
{
"created": "Mon, 19 Mar 2007 14:23:08 GMT",
"version": "v1"
},
{
"created": "Wed, 2 May 2007 18:32:26 GMT",
"version": "v2"
},
{
"created": "Tue, 8 Jul 2008 22:11:45 GMT",
"version": "v3"
}
] | 2009-02-11 | [
[
"Ovalle",
"J",
""
]
] | In the context of the braneworld, a method to find consistent solutions to Einstein's field equations in the interior of a spherically symmetric, static and non uniform stellar distribution with Weyl stresses is developed. This method, based in the fact that any braneworld stellar solution must have the general relativity solution as a limit, produces a constraint which reduces the degrees of freedom on the brane. Hence the non locality and non closure of the braneworld equations can be overcome. The constraint found is physically interpreted as a necessary condition to regain general relativity, and a particular solution for it is used to find an exact and physically acceptable analytical internal solution to no-uniform stellar distributions on the brane. It is shown that such an exact solution is possible due to the fact that bulk corrections to pressure, density and a metric component are a null source of anisotropic effects on the brane. A conjecture is proposed about the possibility of finding physically relevant exact solutions to non-uniform stellar distributions on the brane. |
gr-qc/9809089 | Samuel Rocha Oliveira | Patricio S. Letelier and Samuel R. Oliveira | On Accelerated Black Holes | Substantial revision after referee's comments. 21 pages, 3 figures, 2
tables. (amsmath and graphicx packages). Accepted to Phys. Rev. D | Phys.Rev. D64 (2001) 064005 | 10.1103/PhysRevD.64.064005 | null | gr-qc | null | The static and stationary C-metric are revisited in a generic framework and
their interpretations studied in some detail. Specially those with two event
horizons, one for the black hole and another for the acceleration. We found
that: i) The spacetime of an accelerated static black hole is plagued by either
conical singularities or lack of smoothness and compactness of the black hole
horizon; ii) By using standard black hole thermodynamics we show that
accelerated black holes have higher Hawking temperature than Unruh temperature
of the accelerated frame; iii) The usual upper bound on the product of the mass
and acceleration parameters <1/sqrt(27) is just a coordinate artifact. The main
results are extended to accelerated rotating black holes with no significant
changes.
| [
{
"created": "Wed, 30 Sep 1998 21:02:19 GMT",
"version": "v1"
},
{
"created": "Fri, 23 Jul 1999 22:51:22 GMT",
"version": "v2"
},
{
"created": "Tue, 12 Jun 2001 19:01:41 GMT",
"version": "v3"
}
] | 2009-10-31 | [
[
"Letelier",
"Patricio S.",
""
],
[
"Oliveira",
"Samuel R.",
""
]
] | The static and stationary C-metric are revisited in a generic framework and their interpretations studied in some detail. Specially those with two event horizons, one for the black hole and another for the acceleration. We found that: i) The spacetime of an accelerated static black hole is plagued by either conical singularities or lack of smoothness and compactness of the black hole horizon; ii) By using standard black hole thermodynamics we show that accelerated black holes have higher Hawking temperature than Unruh temperature of the accelerated frame; iii) The usual upper bound on the product of the mass and acceleration parameters <1/sqrt(27) is just a coordinate artifact. The main results are extended to accelerated rotating black holes with no significant changes. |
1507.04810 | Stanley P. Gudder | Stanley Gudder | Curvature and Quantum Mechanics on Covariant Causal Sets | 19 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This article begins by reviewing the causal set approach in discrete quantum
gravity. In our version of this approach a special role is played by covariant
causal sets which we call $c$-causets. The importance of $c$-causets is that
they support the concepts of a natural distance function, geodesics and
curvature in a discrete setting. We then discuss curvature in more detail. By
considering $c$-causets with a maximum and minimum number of paths, we are able
to find $c$-causets with large and small average curvature. We then briefly
discuss our previous work on the inflationary period when the curvature was
essentially zero. Quantum mechanics on $c$-causets is considered next. We first
introduce a free wave equation for $c$-causets. We then show how the state of a
particle with a specified mass (or energy) can be derived from the wave
equation. It is demonstrated for small examples that quantum mechanics predicts
that particles tend to move toward vertices with larger curvature.
| [
{
"created": "Fri, 17 Jul 2015 00:59:46 GMT",
"version": "v1"
}
] | 2015-07-20 | [
[
"Gudder",
"Stanley",
""
]
] | This article begins by reviewing the causal set approach in discrete quantum gravity. In our version of this approach a special role is played by covariant causal sets which we call $c$-causets. The importance of $c$-causets is that they support the concepts of a natural distance function, geodesics and curvature in a discrete setting. We then discuss curvature in more detail. By considering $c$-causets with a maximum and minimum number of paths, we are able to find $c$-causets with large and small average curvature. We then briefly discuss our previous work on the inflationary period when the curvature was essentially zero. Quantum mechanics on $c$-causets is considered next. We first introduce a free wave equation for $c$-causets. We then show how the state of a particle with a specified mass (or energy) can be derived from the wave equation. It is demonstrated for small examples that quantum mechanics predicts that particles tend to move toward vertices with larger curvature. |
1810.06541 | Krzysztof Andrzejewski | K. Andrzejewski, S. Prencel | Niederer's transformation, time-dependent oscillators and polarized
gravitational waves | 26 pages, Substantially revised according to the suggestions of the
referees (the role of the integrals of motion, associated with the conformal
generators, is clarified by means of Ermakov-Lewis invariants). Accepted for
publication in CQG | null | 10.1088/1361-6382/ab2394 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is noted that the Niederer transformation can be used to find the explicit
relation between time-dependent linear oscillators, including the most
interesting case when one of them is harmonic. A geometric interpretation of
this correspondence is provided by certain subclasses of pp-waves; in
particular the ones strictly related to the proper conformal transformations.
This observation allows us to show that the pulses of plane gravitational wave
exhibiting the maximal conformal symmetry are analytically solvable.
Particularly interesting is the circularly polarized family for which some
aspects (such as the classical cross section, velocity memory effect and
impulsive limit) are discussed in more detail. The role of the additional
integrals of motion, associated with the conformal generators, is clarified by
means of Ermakov-Lewis invariants. Possible applications to the description of
interaction of electromagnetic beams with matter are also indicated.
| [
{
"created": "Mon, 15 Oct 2018 17:44:30 GMT",
"version": "v1"
},
{
"created": "Mon, 29 Oct 2018 07:56:45 GMT",
"version": "v2"
},
{
"created": "Thu, 23 May 2019 17:29:58 GMT",
"version": "v3"
}
] | 2019-09-04 | [
[
"Andrzejewski",
"K.",
""
],
[
"Prencel",
"S.",
""
]
] | It is noted that the Niederer transformation can be used to find the explicit relation between time-dependent linear oscillators, including the most interesting case when one of them is harmonic. A geometric interpretation of this correspondence is provided by certain subclasses of pp-waves; in particular the ones strictly related to the proper conformal transformations. This observation allows us to show that the pulses of plane gravitational wave exhibiting the maximal conformal symmetry are analytically solvable. Particularly interesting is the circularly polarized family for which some aspects (such as the classical cross section, velocity memory effect and impulsive limit) are discussed in more detail. The role of the additional integrals of motion, associated with the conformal generators, is clarified by means of Ermakov-Lewis invariants. Possible applications to the description of interaction of electromagnetic beams with matter are also indicated. |
2212.04885 | Bal\'azs Kacskovics | Bal\'azs Kacskovics and D\'aniel Barta and M\'aty\'as Zsolt Vas\'uth | Rapidly rotating neutron stars with realistic nuclear matter equation of
state | 7 pages, 4 figures, conference proceeding | null | 10.1002/asna.20220109 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We performed a comparison of three different numerical codes for constructing
equilibrium models; (I) a code for static equilibrium configurations, (II) an
implementation of the Hartle--Thorne slow-rotation approximation, (III) a
numerical solution of the full Einstein equations by \texttt{LORENE}. We aimed
to construct sequences of uniformly rotating configurations at various rotation
frequencies up to the Keplerian frequency for a hybrid hadronic--quark matter
EOS where a smooth transition is provided between two separate phases. We
investigated the difference of between the results computed by the
implementation of Hartle--Thorne slow-rotation approximation and by
\texttt{LORENE/nrotstar}, respectively. We have conclude that the codes can the
difference between the slow rotating and the fast-rotating approach increase
exponentially, reaching 6.67% for the maximal mass configuration rotating at
the Keplerian frequency.
| [
{
"created": "Fri, 9 Dec 2022 14:39:19 GMT",
"version": "v1"
}
] | 2023-04-05 | [
[
"Kacskovics",
"Balázs",
""
],
[
"Barta",
"Dániel",
""
],
[
"Vasúth",
"Mátyás Zsolt",
""
]
] | We performed a comparison of three different numerical codes for constructing equilibrium models; (I) a code for static equilibrium configurations, (II) an implementation of the Hartle--Thorne slow-rotation approximation, (III) a numerical solution of the full Einstein equations by \texttt{LORENE}. We aimed to construct sequences of uniformly rotating configurations at various rotation frequencies up to the Keplerian frequency for a hybrid hadronic--quark matter EOS where a smooth transition is provided between two separate phases. We investigated the difference of between the results computed by the implementation of Hartle--Thorne slow-rotation approximation and by \texttt{LORENE/nrotstar}, respectively. We have conclude that the codes can the difference between the slow rotating and the fast-rotating approach increase exponentially, reaching 6.67% for the maximal mass configuration rotating at the Keplerian frequency. |
1608.05025 | Afshin Montakhab | Hamid Reza Salahi, Ahmad Sheykhi, and Afshin Montakhab | Effects of Backreaction on Power-Maxwell Holographic Superconductors in
Gauss-Bonnet Gravity | 19 pages, 1 figure | Eur. Phys. J. C 76 (2016) 575 | 10.1140/epjc/s10052-016-4441-x | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analytically and numerically investigate the properties of s-wave
holographic superconductors by considering the effects of scalar and gauge
fields on the background geometry in five dimensional Einstein-Gauss-Bonnet
gravity. We assume the gauge field to be in the form of the Power-Maxwell
nonlinear electrodynamics. We employ the Sturm-Liouville eigenvalue problem for
analytical calculation of the critical temperature and the shooting method for
the numerical investigation. Our numerical and analytical results indicate that
higher curvature corrections affect condensation of the holographic
superconductors with backreaction. We observe that the backreaction can
decrease the critical temperature of the holographic superconductors, while the
Power-Maxwell electrodynamics and Gauss-Bonnet coefficient term may increase
the critical temperature of the holographic superconductors. We find that the
critical exponent has the mean-field value $\beta=1/2$, regardless of the
values of Gauss-Bonnet coefficient, backreaction and Power-Maxwell parameters.
| [
{
"created": "Wed, 17 Aug 2016 17:25:37 GMT",
"version": "v1"
}
] | 2017-03-21 | [
[
"Salahi",
"Hamid Reza",
""
],
[
"Sheykhi",
"Ahmad",
""
],
[
"Montakhab",
"Afshin",
""
]
] | We analytically and numerically investigate the properties of s-wave holographic superconductors by considering the effects of scalar and gauge fields on the background geometry in five dimensional Einstein-Gauss-Bonnet gravity. We assume the gauge field to be in the form of the Power-Maxwell nonlinear electrodynamics. We employ the Sturm-Liouville eigenvalue problem for analytical calculation of the critical temperature and the shooting method for the numerical investigation. Our numerical and analytical results indicate that higher curvature corrections affect condensation of the holographic superconductors with backreaction. We observe that the backreaction can decrease the critical temperature of the holographic superconductors, while the Power-Maxwell electrodynamics and Gauss-Bonnet coefficient term may increase the critical temperature of the holographic superconductors. We find that the critical exponent has the mean-field value $\beta=1/2$, regardless of the values of Gauss-Bonnet coefficient, backreaction and Power-Maxwell parameters. |
1211.0128 | Himanshu Kumar | Himanshu kumar, Sharf Alam, Suhail Ahmad (Jamia Millia Isamia, New
Delhi) | Surface tension with Normal Curvature in Curved Space-Time | 9 pages, RevTex, 1 figure (accepted in Gen. Relativ. Gravit.) | Gen. Relativ. Gravit. (2013) 45:125-142 | 10.1007/s10714-012-1464-y | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | With an aim to include the contribution of surface tension in the action of
the boundary, we define the tangential pressure in terms of surface tension and
Normal curvature in a more naturally geometric way. First, we show that the
negative tangential pressure is independent of the four-velocity of a very thin
hyper-surface. Second, we relate the 3-pressure of a surface layer to the
normal curvature and the surface tension. Third, we relate the surface tension
to the energy of the surface layer. Four, we show that the delta like energy
flows across the hyper-surface will be zero for such a representation of
intrinsic 3-pressure. Five, for the weak field approximation and for static
spherically symmetric configuration, we deduce the classical Kelvin's relation.
Six, we write a modified action for the boundary having contributions both from
surface tension and normal curvature of the surface layer. Also we propose a
method to find the physical action assuming a reference background, where the
background is not flat.
| [
{
"created": "Thu, 1 Nov 2012 09:01:24 GMT",
"version": "v1"
}
] | 2013-01-21 | [
[
"kumar",
"Himanshu",
"",
"Jamia Millia Isamia, New\n Delhi"
],
[
"Alam",
"Sharf",
"",
"Jamia Millia Isamia, New\n Delhi"
],
[
"Ahmad",
"Suhail",
"",
"Jamia Millia Isamia, New\n Delhi"
]
] | With an aim to include the contribution of surface tension in the action of the boundary, we define the tangential pressure in terms of surface tension and Normal curvature in a more naturally geometric way. First, we show that the negative tangential pressure is independent of the four-velocity of a very thin hyper-surface. Second, we relate the 3-pressure of a surface layer to the normal curvature and the surface tension. Third, we relate the surface tension to the energy of the surface layer. Four, we show that the delta like energy flows across the hyper-surface will be zero for such a representation of intrinsic 3-pressure. Five, for the weak field approximation and for static spherically symmetric configuration, we deduce the classical Kelvin's relation. Six, we write a modified action for the boundary having contributions both from surface tension and normal curvature of the surface layer. Also we propose a method to find the physical action assuming a reference background, where the background is not flat. |
gr-qc/0703023 | Davide Batic | D. Batic and H. Schmid | The Dirac propagator in the extreme Kerr metric | 9 pages, one more reference added | J.Phys.A40:13443-13452,2007 | 10.1088/1751-8113/40/44/021 | null | gr-qc | null | Starting with the Dirac equation in the extreme Kerr metric we derive an
integral representation for the propagator of solutions of the Cauchy problem
with initial data in the class of smooth compactly supported functions.
| [
{
"created": "Mon, 5 Mar 2007 08:19:02 GMT",
"version": "v1"
},
{
"created": "Mon, 12 Mar 2007 13:24:24 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Batic",
"D.",
""
],
[
"Schmid",
"H.",
""
]
] | Starting with the Dirac equation in the extreme Kerr metric we derive an integral representation for the propagator of solutions of the Cauchy problem with initial data in the class of smooth compactly supported functions. |
gr-qc/9806065 | Dominic Clancy | Dominic Clancy, James E. Lidsey and Reza Tavakol | Initial Conditions in String Cosmology | 10 pages standard Latex format, no figures. Submitted to Phys. Rev. D | Phys.Rev. D59 (1999) 063511 | 10.1103/PhysRevD.59.063511 | null | gr-qc | null | We take a critical look at a recent conjecture concerning the past attractor
in the pre-big-bang scenario. We argue that the Milne universe is unlikely to
be a general past attractor for such models and support this with a number of
examples.
| [
{
"created": "Mon, 15 Jun 1998 19:56:44 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Clancy",
"Dominic",
""
],
[
"Lidsey",
"James E.",
""
],
[
"Tavakol",
"Reza",
""
]
] | We take a critical look at a recent conjecture concerning the past attractor in the pre-big-bang scenario. We argue that the Milne universe is unlikely to be a general past attractor for such models and support this with a number of examples. |
gr-qc/9910028 | Pantelis S. Apostolopoulos | Michael Tsamparlis and Pantelis S. Apostolopoulos | Comment on Ricci Collineations for type B warped space-times | LaTex, 3 pages, Eq. (9) and reference added, typos corrected; Gen.
Rel. Grav (to appear) | Gen.Rel.Grav. 32 (2000) 281 | 10.1023/A:1001931409928 | null | gr-qc | null | We present two counterexamples to the paper by Carot et al. in Gen. Rel.
Grav. 1997, 29, 1223 and show that the results obtained are correct but not
general.
| [
{
"created": "Fri, 8 Oct 1999 05:51:25 GMT",
"version": "v1"
},
{
"created": "Wed, 2 Feb 2000 12:46:36 GMT",
"version": "v2"
}
] | 2015-06-25 | [
[
"Tsamparlis",
"Michael",
""
],
[
"Apostolopoulos",
"Pantelis S.",
""
]
] | We present two counterexamples to the paper by Carot et al. in Gen. Rel. Grav. 1997, 29, 1223 and show that the results obtained are correct but not general. |
1610.04452 | Robert Beig | Robert Beig, Bernd G. Schmidt | Celestial mechanics of elastic bodies II | 17 pages, second author has chosen to withdraw, small corrections,
version identical to the published one | Class. Quantum Grav. 34 (2017) 085001 | 10.1088/1361-6382/aa6350 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct time independent configurations describing a small elastic body
moving in a circular orbit in the Schwarzschild spacetime. These configurations
are relativistic versions of Newtonian solutions constructed previously by us.
In the process we simplify and sharpen previous results of ours concerning
elastic bodies in rigid rotation.
| [
{
"created": "Fri, 14 Oct 2016 13:28:01 GMT",
"version": "v1"
},
{
"created": "Sat, 25 Mar 2017 17:40:57 GMT",
"version": "v2"
}
] | 2017-03-28 | [
[
"Beig",
"Robert",
""
],
[
"Schmidt",
"Bernd G.",
""
]
] | We construct time independent configurations describing a small elastic body moving in a circular orbit in the Schwarzschild spacetime. These configurations are relativistic versions of Newtonian solutions constructed previously by us. In the process we simplify and sharpen previous results of ours concerning elastic bodies in rigid rotation. |
0803.3327 | \"Ozg\"ur Acik | O. Acik, U. Ertem, M. Onder and A. Vercin | Killing-Yano Forms of a Class of Spherically Symmetric Space-Times I: A
Unified Generation of Killing Vector Fields | 27 pages | null | null | null | gr-qc hep-th math-ph math.MP | http://creativecommons.org/licenses/by/3.0/ | Killing-Yano one forms (duals of Killing vector fields) of a class of
spherically symmetric space-times characterized by four functions are derived
in a unified and exhaustive way. For well-known space-times such as those of
Minkowski, Schwarzschild, Reissner-Nordstrom, Robertson-Walker and several
forms of de Sitter, these forms arise as special cases in a natural way.
Besides its two well-known forms, four more forms of de Sitter space-time are
also established with ten independent Killing vector fields for which four
different time evolution regimes can explicitly be specified by the symmetry
requirement. A family of space-times in which metric characterizing functions
are of the general form and admitting six or seven independent Killing vector
fields is presented.
| [
{
"created": "Sun, 23 Mar 2008 15:48:28 GMT",
"version": "v1"
}
] | 2008-03-27 | [
[
"Acik",
"O.",
""
],
[
"Ertem",
"U.",
""
],
[
"Onder",
"M.",
""
],
[
"Vercin",
"A.",
""
]
] | Killing-Yano one forms (duals of Killing vector fields) of a class of spherically symmetric space-times characterized by four functions are derived in a unified and exhaustive way. For well-known space-times such as those of Minkowski, Schwarzschild, Reissner-Nordstrom, Robertson-Walker and several forms of de Sitter, these forms arise as special cases in a natural way. Besides its two well-known forms, four more forms of de Sitter space-time are also established with ten independent Killing vector fields for which four different time evolution regimes can explicitly be specified by the symmetry requirement. A family of space-times in which metric characterizing functions are of the general form and admitting six or seven independent Killing vector fields is presented. |
2306.07628 | Antonio Ferreiro | Antonio Ferreiro, Jose Navarro-Salas and Silvia Pla | Comment on "Gravitational Pair Production and Black Hole Evaporation" | null | null | null | null | gr-qc hep-ph hep-th | http://creativecommons.org/licenses/by/4.0/ | We scrutinize the recent Letter "Gravitational pair production and black hole
evaporation" by M.F. Wondrak, W.D. van Suijlekom and H. Falcke [Phys. Rev.
Lett. 130, 221502 (2023); arXiv:2305.18521]. We show that some consequences
based on the proposed imaginary part of the lowest order effective action are
in sharp tension with exact results on pair creation in electrodynamics and
cosmology. This casts serious doubt on their claims for particle production in
a Schwarzschild spacetime.
| [
{
"created": "Tue, 13 Jun 2023 08:55:32 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Sep 2023 10:54:48 GMT",
"version": "v2"
}
] | 2023-09-28 | [
[
"Ferreiro",
"Antonio",
""
],
[
"Navarro-Salas",
"Jose",
""
],
[
"Pla",
"Silvia",
""
]
] | We scrutinize the recent Letter "Gravitational pair production and black hole evaporation" by M.F. Wondrak, W.D. van Suijlekom and H. Falcke [Phys. Rev. Lett. 130, 221502 (2023); arXiv:2305.18521]. We show that some consequences based on the proposed imaginary part of the lowest order effective action are in sharp tension with exact results on pair creation in electrodynamics and cosmology. This casts serious doubt on their claims for particle production in a Schwarzschild spacetime. |
1309.6157 | Hossein Ghaffarnejad | Hossein Ghaffarnejad | Spherically symmetric Jordan-Brans-Dicke quantum gravity with de Broglie
Bohm pilot wave perspective | 9 pages | International Journal of Theoretical Physics 2014, online
published 20 March | 10.1007/s10773-014-2059-z | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We obtain two dimensional analogue of the Jordan-Brans-Dicke (JBD) gravity
action described in four dimensional spherically symmetric curved space time
metric. There will be two scalar fields, namely, the Brans Dicke (BD) $\phi$
and scale factor of 2-sphere part of the space time $\psi.$ We obtained
suitable duality transformations between $(\psi,\phi)$ and $(\rho,S)$ where
$\rho$ and $S$ is respectively amplitude and phase part of the corresponding de
Broglie pilot wave function $\Psi(\rho,S)=\sqrt{\rho}e^{iS}.$ Covariant
conservation of mass-energy current density of particles ensemble
$J_a=\rho\partial_aS,$ is established by applying a particular dynamical
conformal frame described by $(\rho,S).$
| [
{
"created": "Mon, 23 Sep 2013 14:35:24 GMT",
"version": "v1"
},
{
"created": "Fri, 24 Jan 2014 20:10:41 GMT",
"version": "v2"
}
] | 2014-03-25 | [
[
"Ghaffarnejad",
"Hossein",
""
]
] | We obtain two dimensional analogue of the Jordan-Brans-Dicke (JBD) gravity action described in four dimensional spherically symmetric curved space time metric. There will be two scalar fields, namely, the Brans Dicke (BD) $\phi$ and scale factor of 2-sphere part of the space time $\psi.$ We obtained suitable duality transformations between $(\psi,\phi)$ and $(\rho,S)$ where $\rho$ and $S$ is respectively amplitude and phase part of the corresponding de Broglie pilot wave function $\Psi(\rho,S)=\sqrt{\rho}e^{iS}.$ Covariant conservation of mass-energy current density of particles ensemble $J_a=\rho\partial_aS,$ is established by applying a particular dynamical conformal frame described by $(\rho,S).$ |
1709.07749 | Tiberiu Harko | Christian G. Boehmer, Piyabut Burikham, Tiberiu Harko, Matthew J. Lake | Does space-time torsion determine the minimum mass of gravitating
particles? | 21 pages, 3 figures; references added; minor revisions, accepted for
publication in EPJC | Eur. Phys. J. C78 (2018) no.3, 253 | 10.1140/epjc/s10052-018-5719-y | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive upper and lower limits for the mass-radius ratio of spin-fluid
spheres in Einstein-Cartan theory, with matter satisfying a linear barotropic
equation of state, and in the presence of a cosmological constant. Adopting a
spherically symmetric interior geometry, we obtain the generalized continuity
and Tolman-Oppenheimer-Volkoff equations for a Weyssenhoff spin-fluid in
hydrostatic equilibrium, expressed in terms of the effective mass, density and
pressure, all of which contain additional contributions from the spin. The
generalized Buchdahl inequality, which remains valid at any point in the
interior, is obtained, and general theoretical limits for the maximum and
minimum mass-radius ratios are derived. As an application of our results we
obtain gravitational red shift bounds for compact spin-fluid objects, which may
(in principle) be used for observational tests of Einstein-Cartan theory in an
astrophysical context. We also briefly consider applications of the
torsion-induced minimum mass to the spin-generalized strong gravity model for
baryons/mesons, and show that the existence of quantum spin imposes a lower
bound for spinning particles, which almost exactly reproduces the electron
mass.
| [
{
"created": "Fri, 22 Sep 2017 13:52:27 GMT",
"version": "v1"
},
{
"created": "Sat, 7 Oct 2017 10:26:17 GMT",
"version": "v2"
},
{
"created": "Thu, 8 Mar 2018 12:37:35 GMT",
"version": "v3"
}
] | 2018-06-25 | [
[
"Boehmer",
"Christian G.",
""
],
[
"Burikham",
"Piyabut",
""
],
[
"Harko",
"Tiberiu",
""
],
[
"Lake",
"Matthew J.",
""
]
] | We derive upper and lower limits for the mass-radius ratio of spin-fluid spheres in Einstein-Cartan theory, with matter satisfying a linear barotropic equation of state, and in the presence of a cosmological constant. Adopting a spherically symmetric interior geometry, we obtain the generalized continuity and Tolman-Oppenheimer-Volkoff equations for a Weyssenhoff spin-fluid in hydrostatic equilibrium, expressed in terms of the effective mass, density and pressure, all of which contain additional contributions from the spin. The generalized Buchdahl inequality, which remains valid at any point in the interior, is obtained, and general theoretical limits for the maximum and minimum mass-radius ratios are derived. As an application of our results we obtain gravitational red shift bounds for compact spin-fluid objects, which may (in principle) be used for observational tests of Einstein-Cartan theory in an astrophysical context. We also briefly consider applications of the torsion-induced minimum mass to the spin-generalized strong gravity model for baryons/mesons, and show that the existence of quantum spin imposes a lower bound for spinning particles, which almost exactly reproduces the electron mass. |
gr-qc/0605118 | Vitor Cardoso | Emanuele Berti, Vitor Cardoso | Quasinormal ringing of Kerr black holes: The excitation factors | 33 pages, 9 figures, 7 tables, RevTeX4. v2: Two new figures and minor
changes in the presentation. Matches version in press in Phys. Rev. D | Phys.Rev. D74 (2006) 104020 | 10.1103/PhysRevD.74.104020 | null | gr-qc astro-ph hep-ph physics.space-ph | null | Distorted black holes radiate gravitational waves. In the so-called ringdown
phase radiation is emitted in a discrete set of complex quasinormal
frequencies, whose values depend only on the black hole's mass and angular
momentum. Ringdown radiation could be detectable with large signal-to-noise
ratio by the Laser Interferometer Space Antenna LISA. If more than one mode is
detected, tests of the black hole nature of the source become possible. The
detectability of different modes depends on their relative excitation, which in
turn depends on the cause of the perturbation (i.e. on the initial data). A
``universal'', initial data-independent measure of the relative mode excitation
is encoded in the poles of the Green's function that propagates small
perturbations of the geometry (``excitation factors''). We compute for the
first time the excitation factors for general-spin perturbations of Kerr black
holes. We find that for corotating modes with $l=m$ the excitation factors tend
to zero in the extremal limit, and that the contribution of the overtones
should be more significant when the black hole is fast rotating. We also
present the first analytical calculation of the large-damping asymptotics of
the excitation factors for static black holes, including the Schwarzschild and
Reissner-Nordstrom metrics. This is an important step to determine the
convergence properties of the quasinormal mode expansion.
| [
{
"created": "Sun, 21 May 2006 20:38:38 GMT",
"version": "v1"
},
{
"created": "Fri, 10 Nov 2006 18:04:19 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Berti",
"Emanuele",
""
],
[
"Cardoso",
"Vitor",
""
]
] | Distorted black holes radiate gravitational waves. In the so-called ringdown phase radiation is emitted in a discrete set of complex quasinormal frequencies, whose values depend only on the black hole's mass and angular momentum. Ringdown radiation could be detectable with large signal-to-noise ratio by the Laser Interferometer Space Antenna LISA. If more than one mode is detected, tests of the black hole nature of the source become possible. The detectability of different modes depends on their relative excitation, which in turn depends on the cause of the perturbation (i.e. on the initial data). A ``universal'', initial data-independent measure of the relative mode excitation is encoded in the poles of the Green's function that propagates small perturbations of the geometry (``excitation factors''). We compute for the first time the excitation factors for general-spin perturbations of Kerr black holes. We find that for corotating modes with $l=m$ the excitation factors tend to zero in the extremal limit, and that the contribution of the overtones should be more significant when the black hole is fast rotating. We also present the first analytical calculation of the large-damping asymptotics of the excitation factors for static black holes, including the Schwarzschild and Reissner-Nordstrom metrics. This is an important step to determine the convergence properties of the quasinormal mode expansion. |
gr-qc/9607021 | Tsvi Piran | Tsvi Piran | Relativity at Action or Gamma-Ray Bursts | 7 pages, 4th prize in this years gravity essay competition to appear
in General Relativity and Gravitation. Complete PS file is available at
ftp://shemesh.fiz.huji.ac.il or at
http://shemesh.fiz.huji.ac.il/papers/essay96.uu | null | 10.1007/BF02113771 | null | gr-qc astro-ph | null | Gamma ray Bursts (GRBs) - short bursts of few hundred keV $\gamma$-rays -
have fascinated astronomers since their accidental discovery in the sixties.
GRBs were ignored by most relativists who did not expect that they are
associated with any relativistic phenomenon. The recent observations of the
BATSE detector on the Compton GRO satellite have revolutionized our ideas on
these bursts and the picture that emerges shows that GRBs are the most
relativistic objects discovered so far.
| [
{
"created": "Mon, 8 Jul 1996 09:03:00 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Piran",
"Tsvi",
""
]
] | Gamma ray Bursts (GRBs) - short bursts of few hundred keV $\gamma$-rays - have fascinated astronomers since their accidental discovery in the sixties. GRBs were ignored by most relativists who did not expect that they are associated with any relativistic phenomenon. The recent observations of the BATSE detector on the Compton GRO satellite have revolutionized our ideas on these bursts and the picture that emerges shows that GRBs are the most relativistic objects discovered so far. |
1106.1751 | Ritabrata Biswas | Sudeshna Mukerji, Nairwita Mazumder, Ritabrata Biswas, Subenoy
Chakraborty | Scalar tensor theory : validity of Cosmic no hair conjecture | 5 pages | null | 10.1139/p11-074 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The paper deals with cosmic no hair conjecture in scalar tensor theory of
gravity. Here we have considered both Jordan frame and Einstein frame to
examine the conjecture. In Jordan frame, one should restrict both the coupling
function of the scalar field and the coupling parameter in addition to the
ususal energy conditions for the the matter field for the validity of CNHC
while in Einstein frame the restrictions are purely on the energy conditions.
| [
{
"created": "Thu, 9 Jun 2011 09:09:39 GMT",
"version": "v1"
}
] | 2015-05-28 | [
[
"Mukerji",
"Sudeshna",
""
],
[
"Mazumder",
"Nairwita",
""
],
[
"Biswas",
"Ritabrata",
""
],
[
"Chakraborty",
"Subenoy",
""
]
] | The paper deals with cosmic no hair conjecture in scalar tensor theory of gravity. Here we have considered both Jordan frame and Einstein frame to examine the conjecture. In Jordan frame, one should restrict both the coupling function of the scalar field and the coupling parameter in addition to the ususal energy conditions for the the matter field for the validity of CNHC while in Einstein frame the restrictions are purely on the energy conditions. |
1407.4037 | Brian Dolan | Brian P. Dolan | Vacuum energy and the latent heat of AdS-Kerr black holes | 15 pages; 4 figures | Phys. Rev. D 90, 084002 (2014) | 10.1103/PhysRevD.90.084002 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Phase transitions for rotating asymptotically anti-de Sitter black holes in
four dimensions are described in the $P-T$ plane, in terms of the Hawking
temperature and the pressure provided by the cosmological constant. The
difference between constant angular momentum and constant angular velocity is
highlighted, the former has a second order phase transition while the latter
does not. If the angular momentum is fixed there a line of first order phase
transitions terminating at a critical point with a second order phase
transition and vanishing latent heat, while if the angular velocity is fixed
there is a line of first order phase transitions terminating at a critical
point with infinite latent heat. For constant angular velocity the analytic
form of the phase boundary is determined, latent heats derived and the
Clapeyron equation verified.
| [
{
"created": "Tue, 15 Jul 2014 16:02:53 GMT",
"version": "v1"
}
] | 2014-10-08 | [
[
"Dolan",
"Brian P.",
""
]
] | Phase transitions for rotating asymptotically anti-de Sitter black holes in four dimensions are described in the $P-T$ plane, in terms of the Hawking temperature and the pressure provided by the cosmological constant. The difference between constant angular momentum and constant angular velocity is highlighted, the former has a second order phase transition while the latter does not. If the angular momentum is fixed there a line of first order phase transitions terminating at a critical point with a second order phase transition and vanishing latent heat, while if the angular velocity is fixed there is a line of first order phase transitions terminating at a critical point with infinite latent heat. For constant angular velocity the analytic form of the phase boundary is determined, latent heats derived and the Clapeyron equation verified. |
2212.06063 | Wei-Can Syu | Wei-Can Syu and Da-Shin Lee | Analogous Hawking radiation from gapped excitations in a transonic flow
of binary Bose-Einstein condensates | Accepted version for publication in Physical Review D: the title
changed; the spatially dependent sound speed and flow velocity profiles
considered; the approximate solution of the gapped mode equations found. 13
pages, 6 figures | null | 10.1103/PhysRevD.107.084049 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We have studied analytically the approximate solutions to the gapped mode
equations in the hydrodynamic regime for a class of binary Bose-Einstein
condensate acoustic black holes. The horizon from the transonic flow is formed
by manipulating the phonon sound speed and the flow velocity with the
experimentally accessible parameters. The asymptotic modes of various
scattering processes are constructed from which to obtain scattering
coefficients and then to further decompose the field operator in terms of the
asymptotic states. Also, the Unruh state is introduced to be the appropriate
state for the description of gravitational collapse of the black hole. The
particle densities of the outgoing modes are computed. The effective energy gap
term in the dispersion relation of the gapped excitations introduces the
threshold frequency $\omega_r$ in the subsonic regime, below which the
propagating modes do not exist. Thus, the particle spectrum of the analogous
Hawking modes in the exterior of the horizon of the subsonic region
significantly deviates from that of the gapless cases near the threshold
frequency due to the modified graybody factor, which vanishes as the mode
frequency is below $\omega_r$.
However, in the interior region of the horizon of the supersonic region, the
spectrum of the particle production of the Hawking partner has the nonthermal
feature. The correlators between the analog Hawking mode and its partner of
relevance to the experimental observations are also investigated and show some
peaks near the threshold frequency $\omega_r$ resulting from the gap energy
term to be seen in future experiments.
| [
{
"created": "Mon, 12 Dec 2022 17:30:56 GMT",
"version": "v1"
},
{
"created": "Thu, 13 Apr 2023 03:55:13 GMT",
"version": "v2"
}
] | 2023-05-10 | [
[
"Syu",
"Wei-Can",
""
],
[
"Lee",
"Da-Shin",
""
]
] | We have studied analytically the approximate solutions to the gapped mode equations in the hydrodynamic regime for a class of binary Bose-Einstein condensate acoustic black holes. The horizon from the transonic flow is formed by manipulating the phonon sound speed and the flow velocity with the experimentally accessible parameters. The asymptotic modes of various scattering processes are constructed from which to obtain scattering coefficients and then to further decompose the field operator in terms of the asymptotic states. Also, the Unruh state is introduced to be the appropriate state for the description of gravitational collapse of the black hole. The particle densities of the outgoing modes are computed. The effective energy gap term in the dispersion relation of the gapped excitations introduces the threshold frequency $\omega_r$ in the subsonic regime, below which the propagating modes do not exist. Thus, the particle spectrum of the analogous Hawking modes in the exterior of the horizon of the subsonic region significantly deviates from that of the gapless cases near the threshold frequency due to the modified graybody factor, which vanishes as the mode frequency is below $\omega_r$. However, in the interior region of the horizon of the supersonic region, the spectrum of the particle production of the Hawking partner has the nonthermal feature. The correlators between the analog Hawking mode and its partner of relevance to the experimental observations are also investigated and show some peaks near the threshold frequency $\omega_r$ resulting from the gap energy term to be seen in future experiments. |
2312.11103 | Stefano Bagnasco | Stefano Bagnasco, Antonella Bozzi, Tassos Fragos, Alba Gonzalvez,
Steffen Hahn, Gary Hemming, Lia Lavezzi, Paul Laycock, Gonzalo Merino, Silvio
Pardi, Steven Schramm, Achim Stahl, Andres Tanasijczuk, Nadia Tonello, Sara
Vallero, John Veitch and Patrice Verdier | Computing Challenges for the Einstein Telescope project | Submitted for the proceedings of CHEP2023 | null | null | null | gr-qc astro-ph.IM | http://creativecommons.org/licenses/by/4.0/ | The discovery of gravitational waves, first observed in September 2015
following the merger of a binary black hole system, has already revolutionised
our understanding of the Universe. This was further enhanced in August 2017,
when the coalescence of a binary neutron star system was observed both with
gravitational waves and a variety of electromagnetic counterparts; this joint
observation marked the beginning of gravitational multimessenger astronomy. The
Einstein Telescope, a proposed next-generation ground-based gravitational-wave
observatory, will dramatically increase the sensitivity to sources: the number
of observations of gravitational waves is expected to increase from roughly 100
per year to roughly 100'000 per year, and signals may be visible for hours at a
time, given the low frequency cutoff of the planned instrument. This increase
in the number of observed events, and the duration with which they are
observed, is hugely beneficial to the scientific goals of the community but
poses a number of significant computing challenges. Moreover, the currently
used computing algorithms do not scale to this new environment, both in terms
of the amount of resources required and the speed with which each signal must
be characterised. This contribution will discuss the Einstein Telescope's
computing challenges, and the activities that are underway to prepare for them.
Available computing resources and technologies will greatly evolve in the years
ahead, and those working to develop the Einstein Telescope data analysis
algorithms will need to take this into account. It will also be important to
factor into the initial development of the experiment's computing model the
availability of huge parallel HPC systems and ubiquitous Cloud computing; the
design of the model will also, for the first time, include the environmental
impact as one of the optimisation metrics.
| [
{
"created": "Mon, 18 Dec 2023 11:03:09 GMT",
"version": "v1"
}
] | 2023-12-19 | [
[
"Bagnasco",
"Stefano",
""
],
[
"Bozzi",
"Antonella",
""
],
[
"Fragos",
"Tassos",
""
],
[
"Gonzalvez",
"Alba",
""
],
[
"Hahn",
"Steffen",
""
],
[
"Hemming",
"Gary",
""
],
[
"Lavezzi",
"Lia",
""
],
[
"Laycock",
"Paul",
""
],
[
"Merino",
"Gonzalo",
""
],
[
"Pardi",
"Silvio",
""
],
[
"Schramm",
"Steven",
""
],
[
"Stahl",
"Achim",
""
],
[
"Tanasijczuk",
"Andres",
""
],
[
"Tonello",
"Nadia",
""
],
[
"Vallero",
"Sara",
""
],
[
"Veitch",
"John",
""
],
[
"Verdier",
"Patrice",
""
]
] | The discovery of gravitational waves, first observed in September 2015 following the merger of a binary black hole system, has already revolutionised our understanding of the Universe. This was further enhanced in August 2017, when the coalescence of a binary neutron star system was observed both with gravitational waves and a variety of electromagnetic counterparts; this joint observation marked the beginning of gravitational multimessenger astronomy. The Einstein Telescope, a proposed next-generation ground-based gravitational-wave observatory, will dramatically increase the sensitivity to sources: the number of observations of gravitational waves is expected to increase from roughly 100 per year to roughly 100'000 per year, and signals may be visible for hours at a time, given the low frequency cutoff of the planned instrument. This increase in the number of observed events, and the duration with which they are observed, is hugely beneficial to the scientific goals of the community but poses a number of significant computing challenges. Moreover, the currently used computing algorithms do not scale to this new environment, both in terms of the amount of resources required and the speed with which each signal must be characterised. This contribution will discuss the Einstein Telescope's computing challenges, and the activities that are underway to prepare for them. Available computing resources and technologies will greatly evolve in the years ahead, and those working to develop the Einstein Telescope data analysis algorithms will need to take this into account. It will also be important to factor into the initial development of the experiment's computing model the availability of huge parallel HPC systems and ubiquitous Cloud computing; the design of the model will also, for the first time, include the environmental impact as one of the optimisation metrics. |
2111.03359 | De-Chang Dai | De-Chang Dai, Djordje Minic and Dejan Stojkovic | Bulk entropy is crucial to validate the second law of the extended black
hole thermodynamics | 9 figures, 7 pages | null | 10.1007/JHEP12(2021)126 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | The extended black hole thermodynamics in which the cosmological constant
plays the role of pressure significantly enriches the phase structure of the
theory. In order to understand the extended black hole thermodynamics more
precisely, we let the value of the cosmological constant vary dynamically via
tunneling from one vacuum to another in a black hole induced vacuum decay. In
this process, entropy of the matter/energy released by a black hole is crucial
to validate the second law of thermodynamics. In other words, without taking
this bulk entropy into account, entropy associated with the black hole and
cosmological horizons may not always increase. Since the bulk entropy is not
represented by the black hole and the cosmological horizons, this result calls
for a more careful interpretation of the holographic principle in which
environmental effects are taken into account.
| [
{
"created": "Fri, 5 Nov 2021 10:01:29 GMT",
"version": "v1"
}
] | 2022-01-05 | [
[
"Dai",
"De-Chang",
""
],
[
"Minic",
"Djordje",
""
],
[
"Stojkovic",
"Dejan",
""
]
] | The extended black hole thermodynamics in which the cosmological constant plays the role of pressure significantly enriches the phase structure of the theory. In order to understand the extended black hole thermodynamics more precisely, we let the value of the cosmological constant vary dynamically via tunneling from one vacuum to another in a black hole induced vacuum decay. In this process, entropy of the matter/energy released by a black hole is crucial to validate the second law of thermodynamics. In other words, without taking this bulk entropy into account, entropy associated with the black hole and cosmological horizons may not always increase. Since the bulk entropy is not represented by the black hole and the cosmological horizons, this result calls for a more careful interpretation of the holographic principle in which environmental effects are taken into account. |
gr-qc/9901080 | T. P. Singh | Sukratu Barve, T. P. Singh and Louis Witten | Spherical gravitational collapse: tangential pressure and related
equations of state | Latex, 26 pages | Gen.Rel.Grav.32:697-717,2000 | 10.1023/A:1001919219247 | null | gr-qc | null | We derive an equation for the acceleration of a fluid element in the
spherical gravitational collapse of a bounded compact object made up of an
imperfect fluid. We show that non-singular as well as singular solutions arise
in the collapse of a fluid initially at rest and having only a tangential
pressure. We obtain an exact solution of Einstein equations, in the form of an
infinite series, for collapse under tangential pressure with a linear equation
of state. We show that if a singularity forms in the tangential pressure model,
the conditions for the singularity to be naked are exactly the same as in the
model of dust collapse.
| [
{
"created": "Thu, 28 Jan 1999 07:04:07 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"Barve",
"Sukratu",
""
],
[
"Singh",
"T. P.",
""
],
[
"Witten",
"Louis",
""
]
] | We derive an equation for the acceleration of a fluid element in the spherical gravitational collapse of a bounded compact object made up of an imperfect fluid. We show that non-singular as well as singular solutions arise in the collapse of a fluid initially at rest and having only a tangential pressure. We obtain an exact solution of Einstein equations, in the form of an infinite series, for collapse under tangential pressure with a linear equation of state. We show that if a singularity forms in the tangential pressure model, the conditions for the singularity to be naked are exactly the same as in the model of dust collapse. |
0705.0513 | Thomas Murphy Jr. | T. W. Murphy Jr., K. Nordtvedt, S. G. Turyshev | Murphy et al. Reply to the Comment by Kopeikin on "Gravitomagnetic
Influence on Gyroscopes and on the Lunar Orbit" | 1 page; accepted for publication in Physcal Review Letters; refers to
gr-qc/0702028 | Phys.Rev.Lett.98:229002,2007 | 10.1103/PhysRevLett.98.229002 | null | gr-qc | null | Lunar laser ranging analysis, as regularly performed in the solar system
barycentric frame, requires the presence of the gravitomagnetic term in the
equation of motion at the strength predicted by general relativity. The same
term is responsible for the Lense Thirring effect. Any attempt to modify the
strength of the gravitomagnetic interaction would have to do so in a way that
does not destroy the fit to lunar ranging data and other observations.
| [
{
"created": "Thu, 3 May 2007 18:34:53 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Murphy",
"T. W.",
"Jr."
],
[
"Nordtvedt",
"K.",
""
],
[
"Turyshev",
"S. G.",
""
]
] | Lunar laser ranging analysis, as regularly performed in the solar system barycentric frame, requires the presence of the gravitomagnetic term in the equation of motion at the strength predicted by general relativity. The same term is responsible for the Lense Thirring effect. Any attempt to modify the strength of the gravitomagnetic interaction would have to do so in a way that does not destroy the fit to lunar ranging data and other observations. |
2304.01252 | Vitor Cardoso | Vitor Cardoso, Francisco Duque, Andrea Maselli, David Pere\~niguez | Constraints on massive gravity from dipolar mode excitations | 5 pages plus Supplemental Material | null | null | null | gr-qc astro-ph.HE hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study extreme-mass-ratio systems in theories admitting the Schwarzschild
solution and propagating a massive graviton. We show that, in addition to small
corrections to the quadrupolar and higher-order modes, a dipolar mode is
excited in these theories and we quantify its excitation. While
LIGO-Virgo-KAGRA observations are not expected to impose meaningful constraints
in the dipolar sector, future observations by the Einstein Telescope or by
LISA, together with bounds from dispersion relations, can rule out theories of
massive gravity admitting vacuum General Relativistic backgrounds. For the
bound to be circumvented, one needs to move away from Ricci-flat solutions, and
enter a territory where constraints based on wave propagation and dispersion
relations are not reliable.
| [
{
"created": "Mon, 3 Apr 2023 18:00:02 GMT",
"version": "v1"
},
{
"created": "Mon, 20 Nov 2023 05:26:39 GMT",
"version": "v2"
}
] | 2023-11-21 | [
[
"Cardoso",
"Vitor",
""
],
[
"Duque",
"Francisco",
""
],
[
"Maselli",
"Andrea",
""
],
[
"Pereñiguez",
"David",
""
]
] | We study extreme-mass-ratio systems in theories admitting the Schwarzschild solution and propagating a massive graviton. We show that, in addition to small corrections to the quadrupolar and higher-order modes, a dipolar mode is excited in these theories and we quantify its excitation. While LIGO-Virgo-KAGRA observations are not expected to impose meaningful constraints in the dipolar sector, future observations by the Einstein Telescope or by LISA, together with bounds from dispersion relations, can rule out theories of massive gravity admitting vacuum General Relativistic backgrounds. For the bound to be circumvented, one needs to move away from Ricci-flat solutions, and enter a territory where constraints based on wave propagation and dispersion relations are not reliable. |
gr-qc/0702026 | Orchidea Maria Lecian | Orchidea Maria Lecian, Giovanni Montani | Electro-weak Model within the framework of Lorentz gauge theory:
Ashtekar variables? | 5 pages, to appear in the Proceedings of the 1st Stueckelberg
Workshop | Nuovo Cim.B122:207-212,2007 | 10.1393/ncb/i2007-10357-y | null | gr-qc | null | The Electroweak (EW) model is geometrized in the framework of a 5D gauge
theory of the Lorentz group, after the implementation of the Kaluza-Klein (KK)
paradigm. The possibility of introducing Ashtekar variables on a 5D KK manifold
is considered on the ground of its geometrical structure.
| [
{
"created": "Mon, 5 Feb 2007 17:30:16 GMT",
"version": "v1"
}
] | 2010-11-11 | [
[
"Lecian",
"Orchidea Maria",
""
],
[
"Montani",
"Giovanni",
""
]
] | The Electroweak (EW) model is geometrized in the framework of a 5D gauge theory of the Lorentz group, after the implementation of the Kaluza-Klein (KK) paradigm. The possibility of introducing Ashtekar variables on a 5D KK manifold is considered on the ground of its geometrical structure. |
0705.3304 | Pinaki Roy | T. Jana and P. Roy | Higher order intertwining approach to quasinormal modes | null | null | 10.1088/1751-8113/40/22/007 | null | gr-qc | null | Using higher order intertwining operators we obtain new exactly solvable
potentials admitting quasinormal mode (QNMs) solutions of the Klein-Gordon
equation. It is also shown that different potentials exhibiting QNMs can be
related through nonlinear supersymmetry.
| [
{
"created": "Wed, 23 May 2007 08:33:36 GMT",
"version": "v1"
}
] | 2009-11-13 | [
[
"Jana",
"T.",
""
],
[
"Roy",
"P.",
""
]
] | Using higher order intertwining operators we obtain new exactly solvable potentials admitting quasinormal mode (QNMs) solutions of the Klein-Gordon equation. It is also shown that different potentials exhibiting QNMs can be related through nonlinear supersymmetry. |
2001.00935 | John W. Moffat | J. W. Moffat | Gravitational Theory of Cosmology, Galaxies and Galaxy Clusters | 9 pages, 2 figures. arXiv admin note: substantial text overlap with
arXiv:1409.0853, arXiv:1510.07037 | The European Physical Journal C (2020) 80:906 | 10.1140/epjc/s10052-020-08482-x | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A modified gravitational theory explains early universe and late time
cosmology, galaxy and galaxy cluster dynamics. The modified gravity (MOG)
theory extends general relativity (GR) by three extra degrees of freedom: a
scalar field $G$, enhancing the strength of the Newtonian gravitational
constant $G_N$, a gravitational, spin 1 vector graviton field $\phi_\mu$, and
the effective mass $\mu$ of the ultralight spin 1 graviton. For $t < t_{\rm
rec}$, where $t_{\rm rec}$ denotes the time of recombination and re-ionization,
the density of the vector graviton $\rho_\phi > \rho_b$, where $\rho_b$ is the
density of baryons, while for $t > t_{\rm rec}$ we have $\rho_b > \rho_\phi$.
The matter density is parameterized by $\Omega_M=\Omega_b+\Omega_\phi+\Omega_r$
where $\Omega_r=\Omega_\gamma+\Omega_\nu$. For the cosmological parameter
values obtained by the Planck Collaboration, the CMB acoustical oscillation
power spectrum, polarization and lensing data can be fitted as in the
$\Lambda$CDM model. When the baryon density $\rho_b$ dominates the late time
universe, MOG explains galaxy rotation curves, the dynamics of galaxy clusters,
galaxy lensing and the galaxy clusters matter power spectrum without dominant
dark matter.
| [
{
"created": "Thu, 2 Jan 2020 22:25:48 GMT",
"version": "v1"
}
] | 2020-10-30 | [
[
"Moffat",
"J. W.",
""
]
] | A modified gravitational theory explains early universe and late time cosmology, galaxy and galaxy cluster dynamics. The modified gravity (MOG) theory extends general relativity (GR) by three extra degrees of freedom: a scalar field $G$, enhancing the strength of the Newtonian gravitational constant $G_N$, a gravitational, spin 1 vector graviton field $\phi_\mu$, and the effective mass $\mu$ of the ultralight spin 1 graviton. For $t < t_{\rm rec}$, where $t_{\rm rec}$ denotes the time of recombination and re-ionization, the density of the vector graviton $\rho_\phi > \rho_b$, where $\rho_b$ is the density of baryons, while for $t > t_{\rm rec}$ we have $\rho_b > \rho_\phi$. The matter density is parameterized by $\Omega_M=\Omega_b+\Omega_\phi+\Omega_r$ where $\Omega_r=\Omega_\gamma+\Omega_\nu$. For the cosmological parameter values obtained by the Planck Collaboration, the CMB acoustical oscillation power spectrum, polarization and lensing data can be fitted as in the $\Lambda$CDM model. When the baryon density $\rho_b$ dominates the late time universe, MOG explains galaxy rotation curves, the dynamics of galaxy clusters, galaxy lensing and the galaxy clusters matter power spectrum without dominant dark matter. |
1203.2016 | Di Liu | Di Liu, Puxun Wu, Hongwei Yu | G\"odel-type universes in f(T) gravity | 18 pages, introduction revised, reference added | Int. J. Mod. Phys. D, 21, 09 (2012) 1250074 | 10.1142/S0218271812500745 | null | gr-qc | http://creativecommons.org/licenses/by/3.0/ | The issue of causality in $f(T)$ gravity is investigated by examining the
possibility of existence of the closed timelike curves in the G\"{o}del-type
metric. By assuming a perfect fluid as the matter source, we find that the
fluid must have an equation of state parameter greater than minus one in order
to allow the G\"{o}del solutions to exist, and furthermore the critical radius
$r_c$, beyond which the causality is broken down, is finite and it depends on
both matter and gravity. Remarkably, for certain $f(T)$ models, the perfect
fluid that allows the G\"{o}del-type solutions can even be normal matter, such
as pressureless matter or radiation. However, if the matter source is a special
scalar field rather than a perfect fluid, then $r_c\rightarrow\infty$ and the
causality violation is thus avoided.
| [
{
"created": "Fri, 9 Mar 2012 08:38:59 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Sep 2012 12:07:51 GMT",
"version": "v2"
},
{
"created": "Mon, 8 Oct 2012 11:39:45 GMT",
"version": "v3"
},
{
"created": "Fri, 12 Oct 2012 13:48:28 GMT",
"version": "v4"
}
] | 2012-10-15 | [
[
"Liu",
"Di",
""
],
[
"Wu",
"Puxun",
""
],
[
"Yu",
"Hongwei",
""
]
] | The issue of causality in $f(T)$ gravity is investigated by examining the possibility of existence of the closed timelike curves in the G\"{o}del-type metric. By assuming a perfect fluid as the matter source, we find that the fluid must have an equation of state parameter greater than minus one in order to allow the G\"{o}del solutions to exist, and furthermore the critical radius $r_c$, beyond which the causality is broken down, is finite and it depends on both matter and gravity. Remarkably, for certain $f(T)$ models, the perfect fluid that allows the G\"{o}del-type solutions can even be normal matter, such as pressureless matter or radiation. However, if the matter source is a special scalar field rather than a perfect fluid, then $r_c\rightarrow\infty$ and the causality violation is thus avoided. |
2301.01186 | Olivier Minazzoli | L. Bernus, O. Minazzoli, A. Fienga, A. Hees, M. Gastineau, J. Laskar,
P. Deram, A. Di Ruscio | Constraining massless dilaton theory at Solar system scales with the
planetary ephemeris INPOP | 29 pages, 6 figures, 5 tables. Might have minor differences with
published version | Physical Review D, Volume 105, Issue 4, article id.044057,
February 2022 | 10.1103/PhysRevD.105.044057 | null | gr-qc astro-ph.EP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We expose the phenomenology of the massless dilaton theory in the Solar
system for a non universal quadratic coupling between the scalar field which
represents the dilaton, and the matter. Modified post-Newtonian equations of
motion of an $N$-body system and the light time travel are derived from the
action of the theory. We use the physical properties of the main planets of the
Solar system to reduce the number of parameters to be tested to 3 in the linear
coupling case. In the linear case, we have an universal coupling constant
$\alpha_0$ and two coupling constants $\alpha_T$ and $\alpha_G$ related
respectively to the telluric bodies and to the gaseous bodies. We then use the
planetary ephemeris, INPOP19a, in order to constrain these constants. We
succeeded to constrain the linear coupling scenario and the constraints read
$\alpha_0=(1.01\pm23.7)\times 10^{-5}$, $\alpha_T=(0.00\pm24.5)\times 10^{-6}$,
$\alpha_G=(-1.46\pm12.0)\times 10^{-5}$, at the 99.5 \% C.L.
| [
{
"created": "Tue, 3 Jan 2023 16:34:01 GMT",
"version": "v1"
}
] | 2023-01-04 | [
[
"Bernus",
"L.",
""
],
[
"Minazzoli",
"O.",
""
],
[
"Fienga",
"A.",
""
],
[
"Hees",
"A.",
""
],
[
"Gastineau",
"M.",
""
],
[
"Laskar",
"J.",
""
],
[
"Deram",
"P.",
""
],
[
"Di Ruscio",
"A.",
""
]
] | We expose the phenomenology of the massless dilaton theory in the Solar system for a non universal quadratic coupling between the scalar field which represents the dilaton, and the matter. Modified post-Newtonian equations of motion of an $N$-body system and the light time travel are derived from the action of the theory. We use the physical properties of the main planets of the Solar system to reduce the number of parameters to be tested to 3 in the linear coupling case. In the linear case, we have an universal coupling constant $\alpha_0$ and two coupling constants $\alpha_T$ and $\alpha_G$ related respectively to the telluric bodies and to the gaseous bodies. We then use the planetary ephemeris, INPOP19a, in order to constrain these constants. We succeeded to constrain the linear coupling scenario and the constraints read $\alpha_0=(1.01\pm23.7)\times 10^{-5}$, $\alpha_T=(0.00\pm24.5)\times 10^{-6}$, $\alpha_G=(-1.46\pm12.0)\times 10^{-5}$, at the 99.5 \% C.L. |
gr-qc/0407090 | Christoph Adami | Christoph Adami and Greg Ver Steeg | Classical information transmission capacity of quantum black holes | 18 pages, 2 figures. Uses iopart.cls | Class. Quantum Grav. 31 (2014) 075015 | null | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The fate of classical information incident on a quantum black hole has been
the subject of an ongoing controversy in theoretical physics, because a
calculation within the framework of semi-classical curved-space quantum field
theory appears to show that the incident information is irretrievably lost, in
contradiction to time-honored principles such as time-reversibility and
unitarity. Here, we show within this framework embedded in quantum
communication theory that signaling from past to future infinity in the
presence of a Schwarzschild black hole can occur with arbitrary accuracy, and
thus that classical information is not lost in black hole dynamics. The
calculation relies on a treatment that is manifestly unitary from the outset,
where probability conservation is guaranteed because black holes stimulate the
emission of radiation in response to infalling matter. This stimulated
radiation is non-thermal, and contains all of the information about the
infalling matter, while Hawking radiation contains none of it.
| [
{
"created": "Fri, 23 Jul 2004 19:33:44 GMT",
"version": "v1"
},
{
"created": "Sat, 14 Aug 2004 00:39:51 GMT",
"version": "v2"
},
{
"created": "Tue, 11 Jan 2005 03:43:39 GMT",
"version": "v3"
},
{
"created": "Wed, 11 Jan 2006 00:58:42 GMT",
"version": "v4"
},
{
"created": "Tue, 18 Sep 2012 17:50:55 GMT",
"version": "v5"
},
{
"created": "Wed, 20 Mar 2013 21:14:57 GMT",
"version": "v6"
},
{
"created": "Thu, 5 Dec 2013 15:30:32 GMT",
"version": "v7"
},
{
"created": "Fri, 14 Mar 2014 17:58:23 GMT",
"version": "v8"
}
] | 2014-03-17 | [
[
"Adami",
"Christoph",
""
],
[
"Steeg",
"Greg Ver",
""
]
] | The fate of classical information incident on a quantum black hole has been the subject of an ongoing controversy in theoretical physics, because a calculation within the framework of semi-classical curved-space quantum field theory appears to show that the incident information is irretrievably lost, in contradiction to time-honored principles such as time-reversibility and unitarity. Here, we show within this framework embedded in quantum communication theory that signaling from past to future infinity in the presence of a Schwarzschild black hole can occur with arbitrary accuracy, and thus that classical information is not lost in black hole dynamics. The calculation relies on a treatment that is manifestly unitary from the outset, where probability conservation is guaranteed because black holes stimulate the emission of radiation in response to infalling matter. This stimulated radiation is non-thermal, and contains all of the information about the infalling matter, while Hawking radiation contains none of it. |
1012.0226 | Lorenzo Iorio | Lorenzo Iorio | Solar system constraints on a Rindler-type extra-acceleration from
modified gravity at large distances | LaTex2e, 22 pages, 6 figures, 2 tables, 32 references. To appear in
Journal of Cosmology and Astroparticle Physics (JCAP) | JCAP05(2011)019 | 10.1088/1475-7516/2011/05/019 | null | gr-qc astro-ph.EP physics.geo-ph physics.space-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analytically work out the orbital effects caused by a Rindlertype
extra-acceleration ARin which naturally arises in some recent models of
modified gravity at large distances. In particular, we focus on the
perturbations induced by it on the two-body range {\rho} and range-rate
{\rho}\cdot which are commonly used in satellite and planetary investigations
as primary observable quantities. The constraints obtained for ARin by
comparing our calculations with the currently available range and range-rate
residuals for some of the major bodies of the solar system, obtained without
explicitly modeling ARin, are 1 - 2 \times 10-13 m s-2 (Mercury and Venus), 1
\times 10-14 m s-2 (Saturn), 1 \times 10-15 m s-2 (Mars), while for a
terrestrial Rindler acceleration we have 5 \times 10-16 m s-2 (Moon). Another
approach which could be followed consists of taking into account ARin in
re-processing all the available data sets with accordingly modified dynamical
models, and estimating a dedicated solve-for parameter explicitly accounting
for it. Anyway, such a method is time-consuming. A preliminary analysis likely
performed in such a way by a different author yields A <= 8\times10-14 m s-2 at
Mars' distance and A < = 1\times10-14 m s-2 at Saturn's distance. The method
adopted here can be easily and straightforwardly extended to other long-range
modified models of gravity as well.
| [
{
"created": "Wed, 1 Dec 2010 15:41:20 GMT",
"version": "v1"
},
{
"created": "Fri, 4 Mar 2011 14:55:35 GMT",
"version": "v2"
},
{
"created": "Tue, 10 May 2011 16:05:47 GMT",
"version": "v3"
}
] | 2011-05-24 | [
[
"Iorio",
"Lorenzo",
""
]
] | We analytically work out the orbital effects caused by a Rindlertype extra-acceleration ARin which naturally arises in some recent models of modified gravity at large distances. In particular, we focus on the perturbations induced by it on the two-body range {\rho} and range-rate {\rho}\cdot which are commonly used in satellite and planetary investigations as primary observable quantities. The constraints obtained for ARin by comparing our calculations with the currently available range and range-rate residuals for some of the major bodies of the solar system, obtained without explicitly modeling ARin, are 1 - 2 \times 10-13 m s-2 (Mercury and Venus), 1 \times 10-14 m s-2 (Saturn), 1 \times 10-15 m s-2 (Mars), while for a terrestrial Rindler acceleration we have 5 \times 10-16 m s-2 (Moon). Another approach which could be followed consists of taking into account ARin in re-processing all the available data sets with accordingly modified dynamical models, and estimating a dedicated solve-for parameter explicitly accounting for it. Anyway, such a method is time-consuming. A preliminary analysis likely performed in such a way by a different author yields A <= 8\times10-14 m s-2 at Mars' distance and A < = 1\times10-14 m s-2 at Saturn's distance. The method adopted here can be easily and straightforwardly extended to other long-range modified models of gravity as well. |
1606.09139 | Andrei Galiautdinov | Andrei Galiautdinov and Sergei M. Kopeikin | Post-Newtonian celestial mechanics in scalar-tensor cosmology | 7 pages, no figures; supplemental materials added: "Derivation of the
wave equations for perturbations", 27 pages, no figures | Phys. Rev. D 94, 044015 (2016) | 10.1103/PhysRevD.94.044015 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Applying the recently developed dynamical perturbation formalism on
cosmological background to scalar-tensor theory, we provide a solid theoretical
basis and a rigorous justification for phenomenological models of orbital
dynamics that are currently used to interpret experimental measurements of the
time-dependent gravitational constant. We derive the field equations for the
scalar-tensor perturbations and study their gauge freedom associated with the
cosmological expansion. We find a new gauge eliminating a prohibitive number of
gauge modes in the field equations and significantly simplifying post-Newtonian
equations of motion for localized astronomical systems in the universe with
time-dependent gravitational constant. We identify several new post-Newtonian
terms and calculate their effect on secular cosmological evolution of the
osculating orbital elements.
| [
{
"created": "Wed, 29 Jun 2016 14:58:07 GMT",
"version": "v1"
},
{
"created": "Tue, 9 Aug 2016 19:10:33 GMT",
"version": "v2"
},
{
"created": "Wed, 12 Jul 2017 17:15:23 GMT",
"version": "v3"
}
] | 2017-07-13 | [
[
"Galiautdinov",
"Andrei",
""
],
[
"Kopeikin",
"Sergei M.",
""
]
] | Applying the recently developed dynamical perturbation formalism on cosmological background to scalar-tensor theory, we provide a solid theoretical basis and a rigorous justification for phenomenological models of orbital dynamics that are currently used to interpret experimental measurements of the time-dependent gravitational constant. We derive the field equations for the scalar-tensor perturbations and study their gauge freedom associated with the cosmological expansion. We find a new gauge eliminating a prohibitive number of gauge modes in the field equations and significantly simplifying post-Newtonian equations of motion for localized astronomical systems in the universe with time-dependent gravitational constant. We identify several new post-Newtonian terms and calculate their effect on secular cosmological evolution of the osculating orbital elements. |
2301.12172 | Titus K Mathew | Rosemin John, Sarath N. and Titus K. Mathew | Thermal evolution and stability analysis of phenomenologically emergent
dark energy model | 14 pages, 10 figures | null | null | null | gr-qc | http://creativecommons.org/publicdomain/zero/1.0/ | The phenomenologically emergent dark energy (PEDE) model is a varying dark
energy model with no extra degrees of freedom proposed by Li and
Shafieloo\citep{Li_2019} to alleviate the Hubble tension. The statistical
consistency of the model has been discussed by many authors. Since the model
depicts a phantom dark energy that increases with redshift, its cosmic
evolution, particularly during the late phase, must be examined. We discover
that the model's Hubble and deceleration parameters display unusual behaviour
in the future, which differs from $\Lambda$CDM cosmology. We find the model
also follows a distinct evolution in the statefinder plane. The phantom nature
of the model leads to the violation of the null energy condition and a decrease
in horizon entropy. The asymptotic future epoch also seems to be unstable based
on our dynamical system analysis as well as the stability analysis based on
dark energy sound speed.
| [
{
"created": "Sat, 28 Jan 2023 12:00:09 GMT",
"version": "v1"
},
{
"created": "Mon, 13 Feb 2023 10:22:07 GMT",
"version": "v2"
},
{
"created": "Tue, 8 Aug 2023 05:14:21 GMT",
"version": "v3"
}
] | 2023-08-09 | [
[
"John",
"Rosemin",
""
],
[
"N.",
"Sarath",
""
],
[
"Mathew",
"Titus K.",
""
]
] | The phenomenologically emergent dark energy (PEDE) model is a varying dark energy model with no extra degrees of freedom proposed by Li and Shafieloo\citep{Li_2019} to alleviate the Hubble tension. The statistical consistency of the model has been discussed by many authors. Since the model depicts a phantom dark energy that increases with redshift, its cosmic evolution, particularly during the late phase, must be examined. We discover that the model's Hubble and deceleration parameters display unusual behaviour in the future, which differs from $\Lambda$CDM cosmology. We find the model also follows a distinct evolution in the statefinder plane. The phantom nature of the model leads to the violation of the null energy condition and a decrease in horizon entropy. The asymptotic future epoch also seems to be unstable based on our dynamical system analysis as well as the stability analysis based on dark energy sound speed. |
1907.11597 | Jan Steinhoff | Andrea Antonelli, Maarten van de Meent, Alessandra Buonanno, Jan
Steinhoff, Justin Vines | Quasi-circular inspirals and plunges from non-spinning
effective-one-body Hamiltonians with gravitational self-force information | 16 pages, 5 figures | Phys. Rev. D 101, 024024 (2020) | 10.1103/PhysRevD.101.024024 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The self-force program aims at accurately modeling relativistic two-body
systems with a small mass ratio (SMR). In the context of the effective-one-body
(EOB) framework, current results from this program can be used to determine the
effective metric components at linear order in the mass ratio, resumming
post-Newtonian (PN) dynamics around the test-particle limit in the process. It
was shown in [Akcay et al., Phys. Rev. D 86 (2012)] that, in the original
(standard) EOB gauge, the SMR contribution to the metric component
$g^\text{eff}_{tt}$ exhibits a coordinate singularity at the light-ring (LR)
radius. In this paper, we adopt a different gauge for the EOB dynamics and
obtain a Hamiltonian that is free of poles at the LR, with complete
circular-orbit information at linear order in the mass ratio and
non-circular-orbit and higher-order-in-mass-ratio terms up to 3PN order. We
confirm the absence of the LR-divergence in such an EOB Hamiltonian via
plunging trajectories through the LR radius. Moreover, we compare the binding
energies and inspiral waveforms of EOB models with SMR, PN and mixed SMR-3PN
information on a quasi-circular inspiral against numerical-relativity
predictions. We find good agreement between NR simulations and EOB models with
SMR-3PN information for both equal and unequal mass ratios. In particular, when
compared to EOB inspiral waveforms with only 3PN information, EOB Hamiltonians
with SMR-3PN information improves the modeling of binary systems with small
mass ratios $q \lesssim 1/3$, with a dephasing accumulated in $\sim$30
gravitational-wave (GW) cycles being of the order of few hundredths of a radian
up to 4 GW cycles before merger.
| [
{
"created": "Fri, 26 Jul 2019 14:39:33 GMT",
"version": "v1"
}
] | 2020-01-15 | [
[
"Antonelli",
"Andrea",
""
],
[
"van de Meent",
"Maarten",
""
],
[
"Buonanno",
"Alessandra",
""
],
[
"Steinhoff",
"Jan",
""
],
[
"Vines",
"Justin",
""
]
] | The self-force program aims at accurately modeling relativistic two-body systems with a small mass ratio (SMR). In the context of the effective-one-body (EOB) framework, current results from this program can be used to determine the effective metric components at linear order in the mass ratio, resumming post-Newtonian (PN) dynamics around the test-particle limit in the process. It was shown in [Akcay et al., Phys. Rev. D 86 (2012)] that, in the original (standard) EOB gauge, the SMR contribution to the metric component $g^\text{eff}_{tt}$ exhibits a coordinate singularity at the light-ring (LR) radius. In this paper, we adopt a different gauge for the EOB dynamics and obtain a Hamiltonian that is free of poles at the LR, with complete circular-orbit information at linear order in the mass ratio and non-circular-orbit and higher-order-in-mass-ratio terms up to 3PN order. We confirm the absence of the LR-divergence in such an EOB Hamiltonian via plunging trajectories through the LR radius. Moreover, we compare the binding energies and inspiral waveforms of EOB models with SMR, PN and mixed SMR-3PN information on a quasi-circular inspiral against numerical-relativity predictions. We find good agreement between NR simulations and EOB models with SMR-3PN information for both equal and unequal mass ratios. In particular, when compared to EOB inspiral waveforms with only 3PN information, EOB Hamiltonians with SMR-3PN information improves the modeling of binary systems with small mass ratios $q \lesssim 1/3$, with a dephasing accumulated in $\sim$30 gravitational-wave (GW) cycles being of the order of few hundredths of a radian up to 4 GW cycles before merger. |
1811.01563 | Dmitri Fursaev | Dmitri V. Fursaev | Massless Cosmic Strings in Expanding Universe | 17 pages, 4 figures | Phys. Rev. D 98, 123531 (2018) | 10.1103/PhysRevD.98.123531 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Circular massless cosmic strings which move with the speed of light in the de
Sitter universe are described. Construction of the background geometry is based
on parabolic isometries of the de Sitter spacetime. Microscopic circular cosmic
strings may appear at the Planck epoch and then grow up to the Hubble size. We
analyze: images of the strings, influence of strings on trajectories of matter,
formation of overdensities, and shifts of energies of photons. These effects
allow one to discriminate massless strings from their massive cousins. The
present work extends our results on straight massless cosmic strings in
Minkowsky spacetime to curved backgrounds.
| [
{
"created": "Mon, 5 Nov 2018 09:19:42 GMT",
"version": "v1"
}
] | 2019-01-02 | [
[
"Fursaev",
"Dmitri V.",
""
]
] | Circular massless cosmic strings which move with the speed of light in the de Sitter universe are described. Construction of the background geometry is based on parabolic isometries of the de Sitter spacetime. Microscopic circular cosmic strings may appear at the Planck epoch and then grow up to the Hubble size. We analyze: images of the strings, influence of strings on trajectories of matter, formation of overdensities, and shifts of energies of photons. These effects allow one to discriminate massless strings from their massive cousins. The present work extends our results on straight massless cosmic strings in Minkowsky spacetime to curved backgrounds. |
1002.4037 | Richard Woodard | S. P. Miao (CECS), N. C. Tsamis (U. of Crete) and R. P. Woodard (U. of
Florida) | De Sitter Breaking through Infrared Divergences | 27 pages, no figures, uses LaTeX 2epsilon | J.Math.Phys.51:072503,2010 | 10.1063/1.3448926 | UFIFT-QG-10-01 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Just because the propagator of some field obeys a de Sitter invariant
equation does not mean it possesses a de Sitter invariant solution. The classic
example is the propagator of a massless, minimally coupled scalar. We show that
the same thing happens for massive scalars with $M_S^2 < 0$, and for massive
transverse vectors with $M_V^2 \leq -2 (D-1) H^2$, where $D$ is the dimension
of spacetime and $H$ is the Hubble parameter. Although all masses in these
ranges give infrared divergent mode sums, using dimensional regularization (or
any other analytic continuation technique) to define the mode sums leads to the
incorrect conclusion that de Sitter invariant solutions exist except at
discrete values of the masses.
| [
{
"created": "Mon, 22 Feb 2010 02:03:34 GMT",
"version": "v1"
}
] | 2011-12-30 | [
[
"Miao",
"S. P.",
"",
"CECS"
],
[
"Tsamis",
"N. C.",
"",
"U. of Crete"
],
[
"Woodard",
"R. P.",
"",
"U. of\n Florida"
]
] | Just because the propagator of some field obeys a de Sitter invariant equation does not mean it possesses a de Sitter invariant solution. The classic example is the propagator of a massless, minimally coupled scalar. We show that the same thing happens for massive scalars with $M_S^2 < 0$, and for massive transverse vectors with $M_V^2 \leq -2 (D-1) H^2$, where $D$ is the dimension of spacetime and $H$ is the Hubble parameter. Although all masses in these ranges give infrared divergent mode sums, using dimensional regularization (or any other analytic continuation technique) to define the mode sums leads to the incorrect conclusion that de Sitter invariant solutions exist except at discrete values of the masses. |
1507.05048 | Michael Good | Michael R.R. Good, Paul R. Anderson and Charles R. Evans | Black Hole - Moving Mirror II: Particle Creation | Contribution to MG14 Proceedings, 5 pages, 4 figures | null | 10.1142/9789813226609_0172 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | There is an exact correspondence between the simplest solution to Einstein's
equations describing the formation of a black hole and a particular moving
mirror trajectory. In both cases the Bogolubov coefficients in 1+1 dimensions
are identical and can be computed analytically. Particle creation is
investigated by using wave packets. The entire particle creation history is
computed, incorporating the early-time non-thermal emission due to the
formation of the black hole (or the early-time acceleration of the moving
mirror) and the evolution to a Planckian spectrum.
| [
{
"created": "Mon, 13 Jul 2015 17:30:31 GMT",
"version": "v1"
},
{
"created": "Wed, 6 Jan 2016 10:52:39 GMT",
"version": "v2"
}
] | 2018-07-27 | [
[
"Good",
"Michael R. R.",
""
],
[
"Anderson",
"Paul R.",
""
],
[
"Evans",
"Charles R.",
""
]
] | There is an exact correspondence between the simplest solution to Einstein's equations describing the formation of a black hole and a particular moving mirror trajectory. In both cases the Bogolubov coefficients in 1+1 dimensions are identical and can be computed analytically. Particle creation is investigated by using wave packets. The entire particle creation history is computed, incorporating the early-time non-thermal emission due to the formation of the black hole (or the early-time acceleration of the moving mirror) and the evolution to a Planckian spectrum. |
1507.02754 | Woei Chet Lim | Woei Chet Lim | Non-orthogonally transitive $G_2$ spike solution | 9 pages, 1 figure | Class. Quantum Grav. 32 (2015) 162001 | 10.1088/0264-9381/32/16/162001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We generalize the orthogonally transitive (OT) $G_2$ spike solution to the
non-OT $G_2$ case. This is achieved by applying Geroch's transformation on a
Kasner seed. The new solution contains two more parameters than the OT $G_2$
spike solution. Unlike the OT $G_2$ spike solution, the new solution always
resolves its spike.
| [
{
"created": "Fri, 10 Jul 2015 00:39:24 GMT",
"version": "v1"
}
] | 2015-07-27 | [
[
"Lim",
"Woei Chet",
""
]
] | We generalize the orthogonally transitive (OT) $G_2$ spike solution to the non-OT $G_2$ case. This is achieved by applying Geroch's transformation on a Kasner seed. The new solution contains two more parameters than the OT $G_2$ spike solution. Unlike the OT $G_2$ spike solution, the new solution always resolves its spike. |
gr-qc/9604005 | Stefan ]minneborg | Stefan Aminneborg, Ingemar Bengtsson, Soren Holst, Peter Peldan
(Fysikum, Stockholm University) | Making Anti-de Sitter Black Holes | LaTeX, 10 pages, 6 postscript figures, uses epsf.tex | Class.Quant.Grav. 13 (1996) 2707-2714 | 10.1088/0264-9381/13/10/010 | USITP 96-4 | gr-qc | null | It is known from the work of Banados et al. that a space-time with event
horizons (much like the Schwarzschild black hole) can be obtained from 2+1
dimensional anti-de Sitter space through a suitable identification of points.
We point out that this can be done in 3+1 dimensions as well. In this way we
obtain black holes with event horizons that are tori or Riemann surfaces of
genus higher than one. They can have either one or two asymptotic regions.
Locally, the space-time is isometric to anti-de Sitter space.
| [
{
"created": "Tue, 2 Apr 1996 18:30:41 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Aminneborg",
"Stefan",
"",
"Fysikum, Stockholm University"
],
[
"Bengtsson",
"Ingemar",
"",
"Fysikum, Stockholm University"
],
[
"Holst",
"Soren",
"",
"Fysikum, Stockholm University"
],
[
"Peldan",
"Peter",
"",
"Fysikum, Stockholm University"
]
] | It is known from the work of Banados et al. that a space-time with event horizons (much like the Schwarzschild black hole) can be obtained from 2+1 dimensional anti-de Sitter space through a suitable identification of points. We point out that this can be done in 3+1 dimensions as well. In this way we obtain black holes with event horizons that are tori or Riemann surfaces of genus higher than one. They can have either one or two asymptotic regions. Locally, the space-time is isometric to anti-de Sitter space. |
1811.02742 | Tiberiu Harko | Bogdan Danila, Tiberiu Harko, Francisco S. N. Lobo, Man Kwong Mak | Spherically symmetric static vacuum solutions in hybrid metric-Palatini
gravity | 22 pages, 11 figures, accepted for publication in PRD | Phys. Rev. D 99, 064028 (2019) | 10.1103/PhysRevD.99.064028 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider vacuum static spherically symmetric solutions in the hybrid
metric-Palatini gravity theory, which is a combination of the metric and
Palatini $f(R)$ formalisms unifying local constraints at the Solar System level
and the late-time cosmic acceleration. We adopt the scalar-tensor
representation of the hybrid metric-Palatini theory, in which the scalar-tensor
definition of the potential can be represented as a Clairaut differential
equation. Due to their mathematical complexity, it is difficult to find exact
solutions of the vacuum field equations, and therefore we adopt a numerical
approach in studying the behavior of the metric functions and of the scalar
field. After reformulating the field equations in a dimensionless form, and by
introducing a suitable independent radial coordinate, the field equations are
solved numerically. We detect the formation of a black hole from the presence
of a singularity in the metric tensor components. Several models, corresponding
to different functional forms of the scalar field potential are considered. The
thermodynamic properties of these black hole solutions (horizon temperature,
specific heat, entropy and evaporation time due to Hawking luminosity) are also
investigated in detail.
| [
{
"created": "Wed, 7 Nov 2018 02:59:44 GMT",
"version": "v1"
},
{
"created": "Sat, 2 Mar 2019 06:52:11 GMT",
"version": "v2"
}
] | 2019-04-03 | [
[
"Danila",
"Bogdan",
""
],
[
"Harko",
"Tiberiu",
""
],
[
"Lobo",
"Francisco S. N.",
""
],
[
"Mak",
"Man Kwong",
""
]
] | We consider vacuum static spherically symmetric solutions in the hybrid metric-Palatini gravity theory, which is a combination of the metric and Palatini $f(R)$ formalisms unifying local constraints at the Solar System level and the late-time cosmic acceleration. We adopt the scalar-tensor representation of the hybrid metric-Palatini theory, in which the scalar-tensor definition of the potential can be represented as a Clairaut differential equation. Due to their mathematical complexity, it is difficult to find exact solutions of the vacuum field equations, and therefore we adopt a numerical approach in studying the behavior of the metric functions and of the scalar field. After reformulating the field equations in a dimensionless form, and by introducing a suitable independent radial coordinate, the field equations are solved numerically. We detect the formation of a black hole from the presence of a singularity in the metric tensor components. Several models, corresponding to different functional forms of the scalar field potential are considered. The thermodynamic properties of these black hole solutions (horizon temperature, specific heat, entropy and evaporation time due to Hawking luminosity) are also investigated in detail. |
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