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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1009.0292 | Carlos O. Lousto | Carlos O. Lousto and Yosef Zlochower | Orbital Evolution of Extreme-Mass-Ratio Black-Hole Binaries with
Numerical Relativity | 4 pages, 4 figures, 3 tables. Matching published version | Phys.Rev.Lett.106:041101,2011 | 10.1103/PhysRevLett.106.041101 | null | gr-qc astro-ph.CO astro-ph.GA astro-ph.HE astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We perform the first fully nonlinear numerical simulations of black-hole
binaries with mass ratios 100:1. Our technique for evolving such extreme mass
ratios is based on the moving puncture approach with a new gauge condition and
an optimal choice of the mesh refinement (plus large computational resources).
We achieve a convergent set of results for simulations starting with a small
nonspinning black hole just outside the ISCO that then performs over two orbits
before plunging into the 100 times more massive black hole. We compute the
gravitational energy and momenta radiated as well as the final remnant
parameters and compare these quantities with the corresponding perturbative
estimates. The results show a close agreement. We briefly discuss the relevance
of this simulations for Advanced LIGO, third-generation ground based detectors,
and LISA observations, and self-force computations.
| [
{
"created": "Wed, 1 Sep 2010 22:04:59 GMT",
"version": "v1"
},
{
"created": "Fri, 1 Jul 2011 17:00:35 GMT",
"version": "v2"
}
] | 2011-07-04 | [
[
"Lousto",
"Carlos O.",
""
],
[
"Zlochower",
"Yosef",
""
]
] | We perform the first fully nonlinear numerical simulations of black-hole binaries with mass ratios 100:1. Our technique for evolving such extreme mass ratios is based on the moving puncture approach with a new gauge condition and an optimal choice of the mesh refinement (plus large computational resources). We achieve a convergent set of results for simulations starting with a small nonspinning black hole just outside the ISCO that then performs over two orbits before plunging into the 100 times more massive black hole. We compute the gravitational energy and momenta radiated as well as the final remnant parameters and compare these quantities with the corresponding perturbative estimates. The results show a close agreement. We briefly discuss the relevance of this simulations for Advanced LIGO, third-generation ground based detectors, and LISA observations, and self-force computations. |
2206.02610 | Mauro Oi | Davide Brundu, Mariano Cadoni, Mauro Oi, Piero Olla, Andrea
Pierfrancesco Sanna | Atmospheric Newtonian noise modeling for third-generation gravitational
wave detectors | 17 pages, 8 figures | null | 10.1103/PhysRevD.106.064040 | null | gr-qc physics.ao-ph physics.flu-dyn | http://creativecommons.org/licenses/by/4.0/ | The sensitivity and the frequency bandwidth of third-generation
gravitational-wave (GW) detectors are such that the Newtonian noise (NN)
signals produced by atmospheric turbulence could become relevant. We build
models for atmospheric NN that take into account finite correlation times and
inhomogeneity along the vertical direction, and are therefore accurate enough
to represent a reliable reference tool for evaluating this kind of noise. We
compute the NN spectral density from our models and compare it with the
expected sensitivity curve of the Einstein Telescope (ET) with the xylophone
design. The noise signal decays exponentially for small values of the frequency
and the detector's depth, followed by a power-law for large values of the
parameters. We find that, when the detector is built at the earth's surface,
the NN contribution in the low-frequency band is above the ET sensitivity curve
for strong wind. Building the detector underground is sufficient to push the
noise signal under the ET sensitivity curve, but the decrement is close to
marginal for strong wind. In light of the slow decay with depth of the NN,
building the detector underground could be only partially effective as passive
noise mitigation.
| [
{
"created": "Mon, 6 Jun 2022 13:29:20 GMT",
"version": "v1"
}
] | 2022-10-05 | [
[
"Brundu",
"Davide",
""
],
[
"Cadoni",
"Mariano",
""
],
[
"Oi",
"Mauro",
""
],
[
"Olla",
"Piero",
""
],
[
"Sanna",
"Andrea Pierfrancesco",
""
]
] | The sensitivity and the frequency bandwidth of third-generation gravitational-wave (GW) detectors are such that the Newtonian noise (NN) signals produced by atmospheric turbulence could become relevant. We build models for atmospheric NN that take into account finite correlation times and inhomogeneity along the vertical direction, and are therefore accurate enough to represent a reliable reference tool for evaluating this kind of noise. We compute the NN spectral density from our models and compare it with the expected sensitivity curve of the Einstein Telescope (ET) with the xylophone design. The noise signal decays exponentially for small values of the frequency and the detector's depth, followed by a power-law for large values of the parameters. We find that, when the detector is built at the earth's surface, the NN contribution in the low-frequency band is above the ET sensitivity curve for strong wind. Building the detector underground is sufficient to push the noise signal under the ET sensitivity curve, but the decrement is close to marginal for strong wind. In light of the slow decay with depth of the NN, building the detector underground could be only partially effective as passive noise mitigation. |
2001.08577 | Thiago R.P. Caram\^es | Thiago R. P. Caram\^es and J. M. Hoff da Silva | Global monopole as a generator of a bulk-brane structure in Brans-Dicke
bulk gravity | 10 pages, 1 figure. Improved version with more discussion added to
the Introduction, section II and conclusion. A new plot was added as well as
new references. Matches version accepted in EPJC | null | 10.1140/epjc/s10052-020-08646-9 | null | gr-qc hep-th | http://creativecommons.org/publicdomain/zero/1.0/ | We investigate a braneworld model generated by a global monopole in the
context of Brans-Dicke gravity. After solving the dynamical equations we found
a model capable to alleviate the so-called hierarchy problem. The obtained
framework is described by a hybrid compactification scheme endowed with a
seven-dimensional spacetime, in which the brane has four non-compact dimensions
and two curled extra dimensions. The relevant aspects of the resulting model
are studied and the requirements to avoid the well known seesaw-like behavior
are discussed. We show that under certain conditions it is possible to
circumvent such a pathological behavior that characterizes most of the models
that exhibit hybrid compactification. Lastly, we deepen our analysis by
considering possible extensions of this model to a setup with multiple branes
and orbifold-like extra dimension. For this, we compute the consistency
conditions to be obeyed by this more general configuration as predicted by the
braneworld sum rules formalism. This study indicates the possibility of
exclusively positive brane tensions in the model.
| [
{
"created": "Thu, 23 Jan 2020 15:05:17 GMT",
"version": "v1"
},
{
"created": "Tue, 17 Nov 2020 14:23:56 GMT",
"version": "v2"
}
] | 2020-11-18 | [
[
"Caramês",
"Thiago R. P.",
""
],
[
"da Silva",
"J. M. Hoff",
""
]
] | We investigate a braneworld model generated by a global monopole in the context of Brans-Dicke gravity. After solving the dynamical equations we found a model capable to alleviate the so-called hierarchy problem. The obtained framework is described by a hybrid compactification scheme endowed with a seven-dimensional spacetime, in which the brane has four non-compact dimensions and two curled extra dimensions. The relevant aspects of the resulting model are studied and the requirements to avoid the well known seesaw-like behavior are discussed. We show that under certain conditions it is possible to circumvent such a pathological behavior that characterizes most of the models that exhibit hybrid compactification. Lastly, we deepen our analysis by considering possible extensions of this model to a setup with multiple branes and orbifold-like extra dimension. For this, we compute the consistency conditions to be obeyed by this more general configuration as predicted by the braneworld sum rules formalism. This study indicates the possibility of exclusively positive brane tensions in the model. |
1708.00507 | S\'ergio Mittmann dos Santos | S. Mittmann dos Santos, J. M. Hoff da Silva and J. L. Cindra | Straight spinning cosmic strings in Brans-Dicke gravity | 13 pages, 1 figure | Mod. Phys. Lett. A 33, 1850051 (2018) | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is presented an exact solution of straight spinning cosmic strings in
Brans-Dicke theory of gravitation. The possibility of the existence of closed
timelike curves around these cosmic strings is analyzed. Furthermore, the
stability about the formation of the topological defect discussed here is
checked. It is shown the existence of a suitable choice for the integration
constants in which closed timelike curves are not allowed. We also verify if it
is possible that the obtained spacetime can be the source that describes the
observed rotational curves in some galaxies.
| [
{
"created": "Tue, 1 Aug 2017 20:50:46 GMT",
"version": "v1"
},
{
"created": "Fri, 18 Aug 2017 22:17:39 GMT",
"version": "v2"
},
{
"created": "Thu, 30 Nov 2017 16:58:16 GMT",
"version": "v3"
}
] | 2022-08-30 | [
[
"Santos",
"S. Mittmann dos",
""
],
[
"da Silva",
"J. M. Hoff",
""
],
[
"Cindra",
"J. L.",
""
]
] | It is presented an exact solution of straight spinning cosmic strings in Brans-Dicke theory of gravitation. The possibility of the existence of closed timelike curves around these cosmic strings is analyzed. Furthermore, the stability about the formation of the topological defect discussed here is checked. It is shown the existence of a suitable choice for the integration constants in which closed timelike curves are not allowed. We also verify if it is possible that the obtained spacetime can be the source that describes the observed rotational curves in some galaxies. |
gr-qc/9601029 | Anders Hoglund | S. Brian Edgar, A. H\"oglund | The Lanczos potential for the Weyl curvature tensor: existence, wave
equation and algorithms | 34 pages, plain TeX | null | null | null | gr-qc | null | In the last few years renewed interest in the 3-tensor potential $L_{abc} $
proposed by Lanczos for the Weyl curvature tensor has not only clarified and
corrected Lanczos's original work, but generalised the concept in a number of
ways. In this paper we carefully summarise and extend some aspects of these
results, and clarify some misunderstandings in the literature. We also clarify
some comments in a recent paper by Dolan and Kim; in addition, we correct some
internal inconsistencies in their paper and extend their results.
The following new results are also presented. The (computer checked)
complicated second order partial differential equation for the 3-potential, in
arbitrary gauge, for Weyl candidates satisfying Bianchi-type equations is given
-- in those $n $-dimensional spaces (with arbitrary signature) for which the
potential exists; this is easily specialised to Lanczos potentials for the Weyl
curvature tensor. It is found that it is {\it only} in 4-dimensional spaces
(with arbitrary signature and gauge), that the non-linear terms disappear and
that the awkward second order derivative terms cancel; for 4-dimensional
spacetimes (with Lorentz signature), this remarkably simple form was originally
found by Illge, using spinor methods. It is also shown that, for most
4-dimensional vacuum spacetimes, any 3-potential in the Lanczos gauges which
satisfies a simple homogeneous wave equation must be a Lanczos potential for
the Weyl curvature tensor of the background vacuum spacetime. This result is
used to prove that the form of a {\it possible} Lanczos potential proposed by
Dolan and Kim for a class of vacuum spacetimes is in fact a genuine Lanczos
potential for these spacetimes.
| [
{
"created": "Fri, 19 Jan 1996 13:44:46 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Edgar",
"S. Brian",
""
],
[
"Höglund",
"A.",
""
]
] | In the last few years renewed interest in the 3-tensor potential $L_{abc} $ proposed by Lanczos for the Weyl curvature tensor has not only clarified and corrected Lanczos's original work, but generalised the concept in a number of ways. In this paper we carefully summarise and extend some aspects of these results, and clarify some misunderstandings in the literature. We also clarify some comments in a recent paper by Dolan and Kim; in addition, we correct some internal inconsistencies in their paper and extend their results. The following new results are also presented. The (computer checked) complicated second order partial differential equation for the 3-potential, in arbitrary gauge, for Weyl candidates satisfying Bianchi-type equations is given -- in those $n $-dimensional spaces (with arbitrary signature) for which the potential exists; this is easily specialised to Lanczos potentials for the Weyl curvature tensor. It is found that it is {\it only} in 4-dimensional spaces (with arbitrary signature and gauge), that the non-linear terms disappear and that the awkward second order derivative terms cancel; for 4-dimensional spacetimes (with Lorentz signature), this remarkably simple form was originally found by Illge, using spinor methods. It is also shown that, for most 4-dimensional vacuum spacetimes, any 3-potential in the Lanczos gauges which satisfies a simple homogeneous wave equation must be a Lanczos potential for the Weyl curvature tensor of the background vacuum spacetime. This result is used to prove that the form of a {\it possible} Lanczos potential proposed by Dolan and Kim for a class of vacuum spacetimes is in fact a genuine Lanczos potential for these spacetimes. |
2004.07487 | Johannes M\"unch | Johannes M\"unch, J\"urgen Struckmeier, David Vasak | Vanishing torsion coupling of the Maxwell field in canonical gauge
theory of gravity | 5 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Maxwell field can be viewed as a $U(1)$-gauge theory, therefore,
generalizing it to form-invariance in dynamical spacetime backgrounds should
take this symmetry into account. This is of essential importance when
generalizations of general relativity to theories with non-vanishing torsion
are considered. Despite the many statements in literature that a $U(1)$-gauge
field cannot couple to torsion, this issue was recently revived. In this letter
we contribute to the discussion by demonstrating via a canonical transformation
within the framework of the DeDonder-Weyl Hamiltonian formalism that a
$U(1)$-gauge field does not couple to torsion.
| [
{
"created": "Thu, 16 Apr 2020 07:10:57 GMT",
"version": "v1"
}
] | 2020-04-17 | [
[
"Münch",
"Johannes",
""
],
[
"Struckmeier",
"Jürgen",
""
],
[
"Vasak",
"David",
""
]
] | The Maxwell field can be viewed as a $U(1)$-gauge theory, therefore, generalizing it to form-invariance in dynamical spacetime backgrounds should take this symmetry into account. This is of essential importance when generalizations of general relativity to theories with non-vanishing torsion are considered. Despite the many statements in literature that a $U(1)$-gauge field cannot couple to torsion, this issue was recently revived. In this letter we contribute to the discussion by demonstrating via a canonical transformation within the framework of the DeDonder-Weyl Hamiltonian formalism that a $U(1)$-gauge field does not couple to torsion. |
2210.13750 | Muhammad Zubair | M. Zubair, Muhammad Ali Raza and Ghulam Abbas | Optical Features of Rotating Black Hole with Nonlinear Electrodynamics | 18 pages, 7 figures, Accepted for Publication in European Physical
Journal C | null | 10.1140/epjc/s10052-022-10925-6 | null | gr-qc | http://creativecommons.org/licenses/by-sa/4.0/ | In this article, we considered the strong field approximation of nonlinear
electrodynamics black hole and constructed its rotating counterpart by applying
the modified Newman-Janis algorithm. The corresponding metric function in the
strong field limit of the static black hole is identified in order to study the
radius of photon sphere. However, the metric function for the rotating
counterpart in the strong field limit is considered in order to study the
horizon radius w.r.t spin parameter. We considered the Hamilton-Jacobi method
to derive the geodesic equations for photon and constructed an orthonormal
tetrad for deriving the equations for celestial coordinates in the observer's
sky. Shadows, distortions and energy emission rates are investigated and the
results are compared for different values of nonlinear electrodynamics
parameter, charge and spin. It is found that the presence of the nonlinear
electrodynamics parameter affects the shape and size of the shadows and thus
the distortion in the case of rotation. It is also found that the nonlinearity
of electrodynamics diminishes the flatness in the shadow due to the effect of
spin and other parameters.
| [
{
"created": "Fri, 21 Oct 2022 13:50:20 GMT",
"version": "v1"
}
] | 2022-11-23 | [
[
"Zubair",
"M.",
""
],
[
"Raza",
"Muhammad Ali",
""
],
[
"Abbas",
"Ghulam",
""
]
] | In this article, we considered the strong field approximation of nonlinear electrodynamics black hole and constructed its rotating counterpart by applying the modified Newman-Janis algorithm. The corresponding metric function in the strong field limit of the static black hole is identified in order to study the radius of photon sphere. However, the metric function for the rotating counterpart in the strong field limit is considered in order to study the horizon radius w.r.t spin parameter. We considered the Hamilton-Jacobi method to derive the geodesic equations for photon and constructed an orthonormal tetrad for deriving the equations for celestial coordinates in the observer's sky. Shadows, distortions and energy emission rates are investigated and the results are compared for different values of nonlinear electrodynamics parameter, charge and spin. It is found that the presence of the nonlinear electrodynamics parameter affects the shape and size of the shadows and thus the distortion in the case of rotation. It is also found that the nonlinearity of electrodynamics diminishes the flatness in the shadow due to the effect of spin and other parameters. |
gr-qc/0703084 | Spiros Cotsakis | Spiros Cotsakis | Talking About Singularities | 29 pages, latex, rapporteur contribution to the Parallel Session on
Cosmological Singularities, MG11, Berlin 2006 | null | 10.1142/9789812834300_0035 | null | gr-qc | null | We discuss some aspects of recent research as well as more general issues
about motivation, useful methods and open problems in the field of cosmological
singularities. In particular, we review some of the approaches to the general
area and include discussions of the method of asymptotic splittings,
singularity and completeness theorems and the use of the Bel-Robinson energy to
prove completeness theorems and classify cosmological singularities.
| [
{
"created": "Thu, 15 Mar 2007 12:11:23 GMT",
"version": "v1"
}
] | 2016-11-15 | [
[
"Cotsakis",
"Spiros",
""
]
] | We discuss some aspects of recent research as well as more general issues about motivation, useful methods and open problems in the field of cosmological singularities. In particular, we review some of the approaches to the general area and include discussions of the method of asymptotic splittings, singularity and completeness theorems and the use of the Bel-Robinson energy to prove completeness theorems and classify cosmological singularities. |
1203.5032 | Guido Cognola | Guido Cognola and Sergio Zerbini | One-loop F(R,P,Q) gravity in de Sitter universe | Latex, 10 pages, to appear in J. Phys. A: Math. Theor. (special issue
in honor of Prof. S. Dowker) | null | 10.1088/1751-8113/45/37/374014 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Motivated by the dark energy issue, the one-loop quantization approach for a
class of relativistic higher order theories is discussed in some detail. A
specific F(R,P,Q) gravity model at the one-loop level in a de Sitter universe
is investigated, extending the similar program developed for the case of $F(R)$
gravity. The stability conditions under arbitrary perturbations are derived.
| [
{
"created": "Thu, 22 Mar 2012 16:25:55 GMT",
"version": "v1"
}
] | 2015-06-04 | [
[
"Cognola",
"Guido",
""
],
[
"Zerbini",
"Sergio",
""
]
] | Motivated by the dark energy issue, the one-loop quantization approach for a class of relativistic higher order theories is discussed in some detail. A specific F(R,P,Q) gravity model at the one-loop level in a de Sitter universe is investigated, extending the similar program developed for the case of $F(R)$ gravity. The stability conditions under arbitrary perturbations are derived. |
1502.03935 | Yuichiro Takushima | Yuichiro Takushima, Ayumu Terukina, Kazuhiro Yamamoto | Third order solutions of the cosmological density perturbations in the
Horndeski's most general scalar-tensor theory with the Vainshtein mechanism | 26 pages, 2 figures | Phys. Rev. D 92, 104033 (2015) | 10.1103/PhysRevD.92.104033 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the third order solutions of the cosmological density perturbations
in the Horndeski's most general scalar-tensor theory under the condition that
the Vainshtein mechanism is at work. In this work, we thoroughly investigate
the independence property of the functions describing the nonlinear
mode-couplings, which is also useful for models within the general relativity.
Then, we find that the solutions of the density contrast and the velocity
divergence up to the third order ones are characterized by 6 parameters.
Furthermore, the 1-loop order power spectra obtained with the third order
solutions are described by 4 parameters. We exemplify the behavior of the
1-loop order power spectra assuming the kinetic gravity braiding model, which
demonstrates that the effect of the modified gravity appears more significantly
in the power spectrum of the velocity divergence than the density contrast.
| [
{
"created": "Fri, 13 Feb 2015 10:36:02 GMT",
"version": "v1"
}
] | 2015-11-25 | [
[
"Takushima",
"Yuichiro",
""
],
[
"Terukina",
"Ayumu",
""
],
[
"Yamamoto",
"Kazuhiro",
""
]
] | We study the third order solutions of the cosmological density perturbations in the Horndeski's most general scalar-tensor theory under the condition that the Vainshtein mechanism is at work. In this work, we thoroughly investigate the independence property of the functions describing the nonlinear mode-couplings, which is also useful for models within the general relativity. Then, we find that the solutions of the density contrast and the velocity divergence up to the third order ones are characterized by 6 parameters. Furthermore, the 1-loop order power spectra obtained with the third order solutions are described by 4 parameters. We exemplify the behavior of the 1-loop order power spectra assuming the kinetic gravity braiding model, which demonstrates that the effect of the modified gravity appears more significantly in the power spectrum of the velocity divergence than the density contrast. |
2108.11995 | Ulrich Sperhake | Thomas Helfer, Ulrich Sperhake, Robin Croft, Miren Radia, Bo-Xuan Ge,
Eugene A. Lim | Malaise and remedy of binary boson-star initial data | 28 pages, 9 figures, submitted to Classical Quantum Gravity | null | 10.1088/1361-6382/ac53b7 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Through numerical simulations of boson-star head-on collisions, we explore
the quality of binary initial data obtained from the superposition of
single-star spacetimes. Our results demonstrate that evolutions starting from a
plain superposition of individual boosted boson-star spacetimes are vulnerable
to significant unphysical artefacts. These difficulties can be overcome with a
simple modification of the initial data suggested in [PRD 99 (2018) 044046] for
collisions of oscillatons. While we specifically consider massive complex
scalar field boson star models up to a 6th-order-polynomial potential, we argue
that this vulnerability is universal and present in other kinds of exotic
compact systems and hence needs to be addressed.
| [
{
"created": "Thu, 26 Aug 2021 18:47:46 GMT",
"version": "v1"
}
] | 2022-04-13 | [
[
"Helfer",
"Thomas",
""
],
[
"Sperhake",
"Ulrich",
""
],
[
"Croft",
"Robin",
""
],
[
"Radia",
"Miren",
""
],
[
"Ge",
"Bo-Xuan",
""
],
[
"Lim",
"Eugene A.",
""
]
] | Through numerical simulations of boson-star head-on collisions, we explore the quality of binary initial data obtained from the superposition of single-star spacetimes. Our results demonstrate that evolutions starting from a plain superposition of individual boosted boson-star spacetimes are vulnerable to significant unphysical artefacts. These difficulties can be overcome with a simple modification of the initial data suggested in [PRD 99 (2018) 044046] for collisions of oscillatons. While we specifically consider massive complex scalar field boson star models up to a 6th-order-polynomial potential, we argue that this vulnerability is universal and present in other kinds of exotic compact systems and hence needs to be addressed. |
1106.2852 | Sijie Gao | Sijie Gao, Changchun Zhong | Non-extremal Kerr black holes as particle accelerators | 11 pages, 5 figures. A few minor changes | Phys.Rev.D84:044006,2011 | 10.1103/PhysRevD.84.044006 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It has been shown that extremal Kerr black holes can be used as particle
accelerators and arbitrarily high energy may be obtained near the event
horizon. We study particle collisions near the event horizon (outer horizon)
and Cauchy horizon (inner horizon) of a non-extremal Kerr black hole. Firstly,
we provide a general proof showing that particles cannot collide with
arbitrarily high energies at the outter horizon. Secondly, we show that
ultraenergetic collisions can occur near the inner horizon of a Kerr black hole
with any spin parameter $a$.
| [
{
"created": "Wed, 15 Jun 2011 01:10:05 GMT",
"version": "v1"
},
{
"created": "Wed, 3 Aug 2011 14:35:02 GMT",
"version": "v2"
}
] | 2011-08-12 | [
[
"Gao",
"Sijie",
""
],
[
"Zhong",
"Changchun",
""
]
] | It has been shown that extremal Kerr black holes can be used as particle accelerators and arbitrarily high energy may be obtained near the event horizon. We study particle collisions near the event horizon (outer horizon) and Cauchy horizon (inner horizon) of a non-extremal Kerr black hole. Firstly, we provide a general proof showing that particles cannot collide with arbitrarily high energies at the outter horizon. Secondly, we show that ultraenergetic collisions can occur near the inner horizon of a Kerr black hole with any spin parameter $a$. |
1602.08878 | Somenath Chakrabarty | Soma Mitra, Sanchari De and Somenath Chakrabarty | Some Theoretical Aspects of Quantum Mechanical Equations in Rindler
Space | 40 pages LATEX file, 3 .eps figures (included) | European Physical Journal PLUS, 132, 114, (2017) | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this article we have investigated some of the theoretical aspects of the
solutions of quantum mechanical equations in Rindler space. We have developed
the formalism for exact analytical solutions for Schr$\ddot{\rm{o}}$dinger
equation and Klein-Gordon equation. Along with the approximate form of
solutions for these two quantum mechanical equations. We have discussed the
physical significance of our findings. The Hamiltonian operator in Rindler
space is found to be non-Hermitian in nature. But the energy eigen values or
the energy eigen spectra are observed to be real. We have noticed that the sole
reason behind such real behavior is the PT symmetric form of the Hamiltonian
operator.
| [
{
"created": "Mon, 29 Feb 2016 09:31:29 GMT",
"version": "v1"
}
] | 2017-03-28 | [
[
"Mitra",
"Soma",
""
],
[
"De",
"Sanchari",
""
],
[
"Chakrabarty",
"Somenath",
""
]
] | In this article we have investigated some of the theoretical aspects of the solutions of quantum mechanical equations in Rindler space. We have developed the formalism for exact analytical solutions for Schr$\ddot{\rm{o}}$dinger equation and Klein-Gordon equation. Along with the approximate form of solutions for these two quantum mechanical equations. We have discussed the physical significance of our findings. The Hamiltonian operator in Rindler space is found to be non-Hermitian in nature. But the energy eigen values or the energy eigen spectra are observed to be real. We have noticed that the sole reason behind such real behavior is the PT symmetric form of the Hamiltonian operator. |
1706.06826 | Cl\'audio Gomes | Orfeu Bertolami, Cl\'audio Gomes and Francisco S.N. Lobo | Gravitational waves in theories with a non-minimal curvature-matter
coupling | 9 pages. Version published at Eur. Phys. J. C | Eur. Phys. J. C (2018) 78:303 | 10.1140/epjc/s10052-018-5781-5 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational waves in the presence of a non-minimal curvature-matter
coupling are analysed, both in the Newman-Penrose and perturbation theory
formalisms. Considering a cosmological constant as a source, the non-minimally
coupled matter-curvature model reduces to $f(R)$ theories. This is in good
agreement with the most recent data. Furthermore, a dark energy-like fluid is
briefly considered, where the propagation equation for the tensor modes differs
from the previous scenario, in that the scalar mode equation has an extra term,
which can be interpreted as the longitudinal mode being the result of the
mixture of two fundamental excitations $\delta R$ and $\delta \rho$.
| [
{
"created": "Wed, 21 Jun 2017 11:15:01 GMT",
"version": "v1"
},
{
"created": "Mon, 15 Jan 2018 23:22:28 GMT",
"version": "v2"
},
{
"created": "Wed, 2 May 2018 16:48:31 GMT",
"version": "v3"
}
] | 2018-05-03 | [
[
"Bertolami",
"Orfeu",
""
],
[
"Gomes",
"Cláudio",
""
],
[
"Lobo",
"Francisco S. N.",
""
]
] | Gravitational waves in the presence of a non-minimal curvature-matter coupling are analysed, both in the Newman-Penrose and perturbation theory formalisms. Considering a cosmological constant as a source, the non-minimally coupled matter-curvature model reduces to $f(R)$ theories. This is in good agreement with the most recent data. Furthermore, a dark energy-like fluid is briefly considered, where the propagation equation for the tensor modes differs from the previous scenario, in that the scalar mode equation has an extra term, which can be interpreted as the longitudinal mode being the result of the mixture of two fundamental excitations $\delta R$ and $\delta \rho$. |
gr-qc/9906018 | G. Dautcourt | G. Dautcourt | Classical back reaction of low-frequency cosmic gravitational radiation | 13 double column pages, no figs, submitted to Phys.Rev.D | Phys.Rev. D60 (1999) 044008 | 10.1103/PhysRevD.60.044008 | null | gr-qc | null | We study in a Brill-Hartle type of approximation the back reaction of a
superposition of linear gravitational waves on the mean gravitational field up
to second order in the wave amplitudes. The background field is taken as an
Einstein-deSitter geometry. In order to follow inflationary scenarios, the
wavelengths are allowed to exceed the temporary Hubble distance. As in optical
coherence theory, the wave amplitudes are considered as random variables, which
form a homogeneous and isotropic stochastic process, sharing the symmetries of
the background metric. The effective stress-energy tensor for the random waves
is calculated in terms of correlation functions and covers subhorizon as well
as superhorizon modes, the latter give in many cases negative contributions to
energy density and pressure. We discuss solutions of the second-order equations
including pure gravitational radiation universes.
| [
{
"created": "Fri, 4 Jun 1999 21:43:45 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Dautcourt",
"G.",
""
]
] | We study in a Brill-Hartle type of approximation the back reaction of a superposition of linear gravitational waves on the mean gravitational field up to second order in the wave amplitudes. The background field is taken as an Einstein-deSitter geometry. In order to follow inflationary scenarios, the wavelengths are allowed to exceed the temporary Hubble distance. As in optical coherence theory, the wave amplitudes are considered as random variables, which form a homogeneous and isotropic stochastic process, sharing the symmetries of the background metric. The effective stress-energy tensor for the random waves is calculated in terms of correlation functions and covers subhorizon as well as superhorizon modes, the latter give in many cases negative contributions to energy density and pressure. We discuss solutions of the second-order equations including pure gravitational radiation universes. |
1511.05545 | Manuel Kraemer | David Brizuela, Claus Kiefer, Manuel Kraemer | Quantum-gravitational effects on gauge-invariant scalar and tensor
perturbations during inflation: The de Sitter case | 21 pages, 5 figures, clarifications and references added, version
accepted for publication in Physical Review D | Phys. Rev. D 93, 104035 (2016) | 10.1103/PhysRevD.93.104035 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present detailed calculations for quantum-gravitational corrections to the
power spectra of gauge-invariant scalar and tensor perturbations during
inflation. This is done by performing a semiclassical Born-Oppenheimer type of
approximation to the Wheeler-DeWitt equation, from which we obtain a
Schroedinger equation with quantum-gravitational correction terms. As a first
step, we perform our calculation for a de Sitter universe and find that the
correction terms lead to an enhancement of power on the largest scales.
| [
{
"created": "Tue, 17 Nov 2015 20:51:36 GMT",
"version": "v1"
},
{
"created": "Thu, 21 Apr 2016 18:57:34 GMT",
"version": "v2"
}
] | 2016-05-19 | [
[
"Brizuela",
"David",
""
],
[
"Kiefer",
"Claus",
""
],
[
"Kraemer",
"Manuel",
""
]
] | We present detailed calculations for quantum-gravitational corrections to the power spectra of gauge-invariant scalar and tensor perturbations during inflation. This is done by performing a semiclassical Born-Oppenheimer type of approximation to the Wheeler-DeWitt equation, from which we obtain a Schroedinger equation with quantum-gravitational correction terms. As a first step, we perform our calculation for a de Sitter universe and find that the correction terms lead to an enhancement of power on the largest scales. |
gr-qc/9305002 | Ng Ka Lok | K. L. Ng | Gravitational form factors of the neutrino | TEX, need PHYZZX.TEX, 16 pages, NTU-TH-03 | Phys.Rev. D47 (1993) 5187-5190 | 10.1103/PhysRevD.47.5187 | null | gr-qc | null | The gravitational properties of the neutrino is studied in the weak field
approximation. By imposing the hermiticity condition, CPT and CP invariance on
the \em tensor matrix element, we shown that the allowed gravitational form
factors for Dirac and Majorana neutrinos are very different. In a CPT and CP
invariant theory, the \em tensor for a Dirac neutrino of the same specie is
characterized by four gravitational form factors. As a result of CPT
invariance, the \em tensor for a Majorana neutrino of the same specie has five
form factors. In a CP invariant theory, if the initial and final Majorana
neutrinos have the same (opposite) CP parity, then only tensor (pseudo-tensor)
type transition are allowed.
| [
{
"created": "Mon, 3 May 1993 23:24:45 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Ng",
"K. L.",
""
]
] | The gravitational properties of the neutrino is studied in the weak field approximation. By imposing the hermiticity condition, CPT and CP invariance on the \em tensor matrix element, we shown that the allowed gravitational form factors for Dirac and Majorana neutrinos are very different. In a CPT and CP invariant theory, the \em tensor for a Dirac neutrino of the same specie is characterized by four gravitational form factors. As a result of CPT invariance, the \em tensor for a Majorana neutrino of the same specie has five form factors. In a CP invariant theory, if the initial and final Majorana neutrinos have the same (opposite) CP parity, then only tensor (pseudo-tensor) type transition are allowed. |
1404.0687 | Sam Dolan Dr | Carolina L. Benone, Ednilton S. de Oliveira, Sam R. Dolan and Lu\'is
C. B. Crispino | Absorption of a massive scalar field by a charged black hole | 12 pages, 12 figures. To match published version | Phys.Rev.D 89, 104053 (2014) | 10.1103/PhysRevD.89.104053 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We calculate the absorption cross section of a massive neutral scalar field
impinging upon a Reissner-Nordstr\"om black hole. First, we derive key
approximations in the high- and low-frequency regimes. Next, we develop a
numerical method to compute the cross section at intermediate frequencies, and
present a selection of results. Finally, we draw together our complementary
approaches to give a quantitative full-spectrum description of absorption.
| [
{
"created": "Wed, 2 Apr 2014 20:05:26 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Jul 2014 08:22:51 GMT",
"version": "v2"
}
] | 2014-07-16 | [
[
"Benone",
"Carolina L.",
""
],
[
"de Oliveira",
"Ednilton S.",
""
],
[
"Dolan",
"Sam R.",
""
],
[
"Crispino",
"Luís C. B.",
""
]
] | We calculate the absorption cross section of a massive neutral scalar field impinging upon a Reissner-Nordstr\"om black hole. First, we derive key approximations in the high- and low-frequency regimes. Next, we develop a numerical method to compute the cross section at intermediate frequencies, and present a selection of results. Finally, we draw together our complementary approaches to give a quantitative full-spectrum description of absorption. |
1211.6983 | S Habib Mazharimousavi | M. Halilsoy and S. Habib Mazharimousavi | Unified Bertotti-Robinson and Melvin Spacetimes | 8 pages 3 figures, major revision | Phys. Rev. D 88, 064021 (2013) [8 pages] | 10.1103/PhysRevD.88.064021 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a solution for the Einstein-Maxwell (EM) equations which unifies
both the magnetic Bertotti-Robinson (BR) and Melvin (ML) solutions as a single
metric in the axially symmetric coordinates ${t,\rho,z,\varphi} $. Depending on
the strength of magnetic field the spacetime manifold, unlike the cases of
separate BR and ML spacetime, develops singularity on the symmetry axis ($\rho
=0$). Our analysis shows, beside other things that there are regions
inaccessible to all null geodesics.
| [
{
"created": "Sat, 24 Nov 2012 10:30:37 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Aug 2013 08:23:53 GMT",
"version": "v2"
}
] | 2013-09-17 | [
[
"Halilsoy",
"M.",
""
],
[
"Mazharimousavi",
"S. Habib",
""
]
] | We present a solution for the Einstein-Maxwell (EM) equations which unifies both the magnetic Bertotti-Robinson (BR) and Melvin (ML) solutions as a single metric in the axially symmetric coordinates ${t,\rho,z,\varphi} $. Depending on the strength of magnetic field the spacetime manifold, unlike the cases of separate BR and ML spacetime, develops singularity on the symmetry axis ($\rho =0$). Our analysis shows, beside other things that there are regions inaccessible to all null geodesics. |
2212.13590 | Horacio Santana Vieira | H. S. Vieira | Quasibound states of analytic black-hole configurations in three and
four dimensions | 15 pages, 6 figures, 2 tables. Matches published version in PRD | Phys. Rev. D 107, 104011 (2023) | 10.1103/PhysRevD.107.104011 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we analyze the sound perturbation of Unruh's acoustic effective
geometry in both (2+1) and (3+1) spacetime dimensions and present an exact
analytical expression for the quasibound states of these idealized black-hole
configurations by using a new approach recently developed, which uses the
polynomial conditions of the hypergeometric functions. Our main goal is to
discuss the effects of having an event horizon in such effective metrics. We
also discuss the stability of the systems and present the radial eigenfunctions
related to these quasibound state frequencies. These metrics assume just the
form it has for a Schwarzschild black hole near the event horizon, and
therefore may, in principle, shed some light into the underlying classical and
quantum physics of astrophysical black holes through analog acoustic probes.
| [
{
"created": "Tue, 27 Dec 2022 19:26:21 GMT",
"version": "v1"
},
{
"created": "Mon, 22 May 2023 14:23:25 GMT",
"version": "v2"
}
] | 2023-05-23 | [
[
"Vieira",
"H. S.",
""
]
] | In this work we analyze the sound perturbation of Unruh's acoustic effective geometry in both (2+1) and (3+1) spacetime dimensions and present an exact analytical expression for the quasibound states of these idealized black-hole configurations by using a new approach recently developed, which uses the polynomial conditions of the hypergeometric functions. Our main goal is to discuss the effects of having an event horizon in such effective metrics. We also discuss the stability of the systems and present the radial eigenfunctions related to these quasibound state frequencies. These metrics assume just the form it has for a Schwarzschild black hole near the event horizon, and therefore may, in principle, shed some light into the underlying classical and quantum physics of astrophysical black holes through analog acoustic probes. |
0801.3429 | Nickolas Fotopoulos | Nickolas V Fotopoulos (for the LIGO Scientific Collaboration) | Searching for stochastic gravitational-wave background with the
co-located LIGO interferometers | Proceedings paper from the 7th Edoardo Amaldi Conference on
Gravitational Waves, held in Sydney, Australia from 8-14 July 2007. Accepted
to J. Phys.: Conf. Ser | J.Phys.Conf.Ser.122:012032,2008 | 10.1088/1742-6596/122/1/012032 | null | gr-qc | null | This paper presents techniques developed by the LIGO Scientific Collaboration
to search for the stochastic gravitational-wave background using the co-located
pair of LIGO interferometers at Hanford, WA. We use correlations between
interferometers and environment monitoring instruments, as well as time-shifts
between two interferometers (described here for the first time) to identify
correlated noise from non-gravitational sources. We veto particularly noisy
frequency bands and assess the level of residual non-gravitational coupling
that exists in the surviving data.
| [
{
"created": "Tue, 22 Jan 2008 17:55:47 GMT",
"version": "v1"
}
] | 2019-08-13 | [
[
"Fotopoulos",
"Nickolas V",
"",
"for the LIGO Scientific Collaboration"
]
] | This paper presents techniques developed by the LIGO Scientific Collaboration to search for the stochastic gravitational-wave background using the co-located pair of LIGO interferometers at Hanford, WA. We use correlations between interferometers and environment monitoring instruments, as well as time-shifts between two interferometers (described here for the first time) to identify correlated noise from non-gravitational sources. We veto particularly noisy frequency bands and assess the level of residual non-gravitational coupling that exists in the surviving data. |
1609.04332 | Andrei Dubikovsky | K.V. Antipin, A.I. Dubikovsky, P.K. Silaev | Properties of collapse dynamics in relativistic theory of gravitation in
the case of smooth initial matter distributions | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We use both numerical and analytical approaches to study the dynamics of the
gravitational collapse in the framework of the relativistic theory of
gravitation (RTG). We use various equations of state for the collapsing matter
and relatively realistic initial conditions with smooth matter distribution,
which corresponds to static solution for the given equation of state. We also
obtain results concerning the influence of the graviton mass on the properties
of static solutions. We specify several characteristics of the process of the
collapse, in particular, we determine the dependence of the turning point time
(when contraction is replaced by inflation) on the graviton mass. We also study
the influence of non-zero pressure on the dynamics of the collapse.
| [
{
"created": "Wed, 14 Sep 2016 16:18:06 GMT",
"version": "v1"
}
] | 2016-09-15 | [
[
"Antipin",
"K. V.",
""
],
[
"Dubikovsky",
"A. I.",
""
],
[
"Silaev",
"P. K.",
""
]
] | We use both numerical and analytical approaches to study the dynamics of the gravitational collapse in the framework of the relativistic theory of gravitation (RTG). We use various equations of state for the collapsing matter and relatively realistic initial conditions with smooth matter distribution, which corresponds to static solution for the given equation of state. We also obtain results concerning the influence of the graviton mass on the properties of static solutions. We specify several characteristics of the process of the collapse, in particular, we determine the dependence of the turning point time (when contraction is replaced by inflation) on the graviton mass. We also study the influence of non-zero pressure on the dynamics of the collapse. |
1801.00133 | Yu-Ping Wang | Yu-Ping Wang | A Model of the Collapse and Evaporation of Charged Black Holes | 23 pages, 3 figures; fixed typo | null | 10.1088/1361-6382/aae256 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, a natural generalization of KMY model is proposed for the
evaporation of charged black holes. Within the proposed model, the back
reaction of Hawking radiation is considered. More specifically, we consider the
equation $G_{\mu\nu} = 8\pi \langle T_{\mu\nu}\rangle$, in which the matter
content $\langle T_{\mu\nu}\rangle$ is assumed spherically symmetric. With this
equation of motion, the asymptotic behavior of the model is analyzed. Two kinds
of matter contents are taken into consideration in this paper. In the first
case (the thin-shell model), the infalling matter is simulated by a null-like
charged sphere collapsing into its center. In the second case, we consider a
continuous distribution of spherical symmetric infalling null-like charged
matter. It is simulated by taking the continuous limit of many co-centric
spheres collapsing into the center. We find that in the thin-shell case, an
event horizon forms and the shell passes through the horizon before becoming
extremal, provided that it is not initially near-extremal. In the case of
continuous matter distribution, we consider explicitly an extremal center
covered by neutral infalling matter and find that the event horizon also forms.
The black hole itself will become near-extremal eventually, leaving possibly a
non-electromagnetic energy residue less than the order of
$\ell_{p}^{4}/e_{0}^{3}$. The details of the behavior of these models are
explicitly worked out in this paper.
| [
{
"created": "Sat, 30 Dec 2017 13:32:16 GMT",
"version": "v1"
},
{
"created": "Thu, 1 Mar 2018 12:47:22 GMT",
"version": "v2"
}
] | 2018-10-24 | [
[
"Wang",
"Yu-Ping",
""
]
] | In this paper, a natural generalization of KMY model is proposed for the evaporation of charged black holes. Within the proposed model, the back reaction of Hawking radiation is considered. More specifically, we consider the equation $G_{\mu\nu} = 8\pi \langle T_{\mu\nu}\rangle$, in which the matter content $\langle T_{\mu\nu}\rangle$ is assumed spherically symmetric. With this equation of motion, the asymptotic behavior of the model is analyzed. Two kinds of matter contents are taken into consideration in this paper. In the first case (the thin-shell model), the infalling matter is simulated by a null-like charged sphere collapsing into its center. In the second case, we consider a continuous distribution of spherical symmetric infalling null-like charged matter. It is simulated by taking the continuous limit of many co-centric spheres collapsing into the center. We find that in the thin-shell case, an event horizon forms and the shell passes through the horizon before becoming extremal, provided that it is not initially near-extremal. In the case of continuous matter distribution, we consider explicitly an extremal center covered by neutral infalling matter and find that the event horizon also forms. The black hole itself will become near-extremal eventually, leaving possibly a non-electromagnetic energy residue less than the order of $\ell_{p}^{4}/e_{0}^{3}$. The details of the behavior of these models are explicitly worked out in this paper. |
1107.5185 | Jacek Puchta M.Sc. | Marcin Kisielowski, Jerzy Lewandowski, Jacek Puchta | Feynman diagrammatic approach to spin foams | 36 pages, 23 figures | null | 10.1088/0264-9381/29/1/015009 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | "The Spin Foams for People Without the 3d/4d Imagination" could be an
alternative title of our work. We derive spin foams from operator spin network
diagrams} we introduce. Our diagrams are the spin network analogy of the
Feynman diagrams. Their framework is compatible with the framework of Loop
Quantum Gravity. For every operator spin network diagram we construct a
corresponding operator spin foam. Admitting all the spin networks of LQG and
all possible diagrams leads to a clearly defined large class of operator spin
foams. In this way our framework provides a proposal for a class of 2-cell
complexes that should be used in the spin foam theories of LQG. Within this
class, our diagrams are just equivalent to the spin foams. The advantage,
however, in the diagram framework is, that it is self contained, all the
amplitudes can be calculated directly from the diagrams without explicit
visualization of the corresponding spin foams. The spin network diagram
operators and amplitudes are consistently defined on their own. Each diagram
encodes all the combinatorial information. We illustrate applications of our
diagrams: we introduce a diagram definition of Rovelli's surface amplitudes as
well as of the canonical transition amplitudes. Importantly, our operator spin
network diagrams are defined in a sufficiently general way to accommodate all
the versions of the EPRL or the FK model, as well as other possible models. The
diagrams are also compatible with the structure of the LQG Hamiltonian
operators, what is an additional advantage. Finally, a scheme for a complete
definition of a spin foam theory by declaring a set of interaction vertices
emerges from the examples presented at the end of the paper.
| [
{
"created": "Tue, 26 Jul 2011 11:59:05 GMT",
"version": "v1"
}
] | 2015-05-28 | [
[
"Kisielowski",
"Marcin",
""
],
[
"Lewandowski",
"Jerzy",
""
],
[
"Puchta",
"Jacek",
""
]
] | "The Spin Foams for People Without the 3d/4d Imagination" could be an alternative title of our work. We derive spin foams from operator spin network diagrams} we introduce. Our diagrams are the spin network analogy of the Feynman diagrams. Their framework is compatible with the framework of Loop Quantum Gravity. For every operator spin network diagram we construct a corresponding operator spin foam. Admitting all the spin networks of LQG and all possible diagrams leads to a clearly defined large class of operator spin foams. In this way our framework provides a proposal for a class of 2-cell complexes that should be used in the spin foam theories of LQG. Within this class, our diagrams are just equivalent to the spin foams. The advantage, however, in the diagram framework is, that it is self contained, all the amplitudes can be calculated directly from the diagrams without explicit visualization of the corresponding spin foams. The spin network diagram operators and amplitudes are consistently defined on their own. Each diagram encodes all the combinatorial information. We illustrate applications of our diagrams: we introduce a diagram definition of Rovelli's surface amplitudes as well as of the canonical transition amplitudes. Importantly, our operator spin network diagrams are defined in a sufficiently general way to accommodate all the versions of the EPRL or the FK model, as well as other possible models. The diagrams are also compatible with the structure of the LQG Hamiltonian operators, what is an additional advantage. Finally, a scheme for a complete definition of a spin foam theory by declaring a set of interaction vertices emerges from the examples presented at the end of the paper. |
gr-qc/0608087 | Peter Hogan | C. Barrabes and P. A. Hogan | The Bell-Szekeres Solution and Related Solutions of the Einstein-Maxwell
Equations | 18 pages, Latex file | Class.Quant.Grav. 23 (2006) 5265-5278 | 10.1088/0264-9381/23/17/010 | null | gr-qc | null | A novel technique for solving some head-on collisions of plane homogeneous
light-like signals in Einstein-Maxwell theory is described. The technique is a
by-product of a re-examination of the fundamental Bell-Szekeres solution in
this field of study. Extensions of the Bell-Szekeres collision problem to
include light-like shells and gravitational waves are described and a family of
solutions having geometrical and topological properties in common with the
Bell-Szekeres solution is derived.
| [
{
"created": "Fri, 18 Aug 2006 08:57:28 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Barrabes",
"C.",
""
],
[
"Hogan",
"P. A.",
""
]
] | A novel technique for solving some head-on collisions of plane homogeneous light-like signals in Einstein-Maxwell theory is described. The technique is a by-product of a re-examination of the fundamental Bell-Szekeres solution in this field of study. Extensions of the Bell-Szekeres collision problem to include light-like shells and gravitational waves are described and a family of solutions having geometrical and topological properties in common with the Bell-Szekeres solution is derived. |
gr-qc/9412065 | Justin D. Hayward | J. D. Hayward | Entropy in the RST Model | 10 pages, minor revisions, published version in Latex | Phys.Rev. D52 (1995) 2239-2244 | 10.1103/PhysRevD.52.2239 | DAMTP-R94/61 | gr-qc hep-th | null | The RST Model is given boundary term and Z-field so that it is well-posed and
local. The Euclidean method is described for general theory and used to
calculate the RST intrinsic entropy. The evolution of this entropy for the
shockwave solutions is found and obeys a second law.
| [
{
"created": "Wed, 21 Dec 1994 12:12:00 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Aug 1995 15:51:59 GMT",
"version": "v2"
}
] | 2009-10-22 | [
[
"Hayward",
"J. D.",
""
]
] | The RST Model is given boundary term and Z-field so that it is well-posed and local. The Euclidean method is described for general theory and used to calculate the RST intrinsic entropy. The evolution of this entropy for the shockwave solutions is found and obeys a second law. |
gr-qc/0502096 | Pavel Krtous | Pavel Krtous, Jiri Podolsky | Asymptotic directional structure of radiation for fields of algebraic
type D | 20 pages, 6 figures | Czech.J.Phys. 55 (2005) 119-138 | 10.1007/BF03031996 | null | gr-qc | null | The directional behavior of dominant components of algebraically special
spin-s fields near a spacelike, timelike or null conformal infinity is studied.
By extending our previous general investigations we concentrate on fields which
admit a pair of equivalent algebraically special null directions, such as the
Petrov type D gravitational fields or algebraically general electromagnetic
fields. We introduce and discuss a canonical choice of the reference tetrad
near infinity in all possible situations, and we present the corresponding
asymptotic directional structures using the most natural parametrizations.
| [
{
"created": "Tue, 22 Feb 2005 17:21:53 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Krtous",
"Pavel",
""
],
[
"Podolsky",
"Jiri",
""
]
] | The directional behavior of dominant components of algebraically special spin-s fields near a spacelike, timelike or null conformal infinity is studied. By extending our previous general investigations we concentrate on fields which admit a pair of equivalent algebraically special null directions, such as the Petrov type D gravitational fields or algebraically general electromagnetic fields. We introduce and discuss a canonical choice of the reference tetrad near infinity in all possible situations, and we present the corresponding asymptotic directional structures using the most natural parametrizations. |
1402.0205 | Jian-Yang Zhu | Xiao-Min Zhang and Jian-Yang Zhu | Extension of warm inflation to noncanonical scalar fields | 7 pages, 0 figures, accepted by Physical Review D | Phys. Rev. D 90, 123519 (2014) | 10.1103/PhysRevD.90.123519 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We extend the warm inflationary scenario to the case of the noncanonical
scalar fields. The equation of motion and the other basic equations of this new
scenario are obtained. The Hubble damped term is enhanced in noncanonical
inflation. A linear stability analysis is performed to give the proper
slow-roll conditions in warm noncanonical inflation. We study the density
fluctuations in the new picture and obtain an approximate analytic expression
of the power spectrum. The energy scale at the horizon crossing is depressed by
both noncanonical effect and thermal effect, and so is the tensor-to-scalar
ratio. Besides the synergy, the noncanonical effect and the thermal effect are
competing in the case of the warm noncanonical inflation.
| [
{
"created": "Sun, 2 Feb 2014 15:35:38 GMT",
"version": "v1"
},
{
"created": "Sun, 14 Dec 2014 14:34:25 GMT",
"version": "v2"
}
] | 2014-12-24 | [
[
"Zhang",
"Xiao-Min",
""
],
[
"Zhu",
"Jian-Yang",
""
]
] | We extend the warm inflationary scenario to the case of the noncanonical scalar fields. The equation of motion and the other basic equations of this new scenario are obtained. The Hubble damped term is enhanced in noncanonical inflation. A linear stability analysis is performed to give the proper slow-roll conditions in warm noncanonical inflation. We study the density fluctuations in the new picture and obtain an approximate analytic expression of the power spectrum. The energy scale at the horizon crossing is depressed by both noncanonical effect and thermal effect, and so is the tensor-to-scalar ratio. Besides the synergy, the noncanonical effect and the thermal effect are competing in the case of the warm noncanonical inflation. |
2101.07790 | Koray D\"uzta\c{s} | Koray D\"uzta\c{s} | The variational method, backreactions, and the absorption probability in
Wald type problems | Accepted to appear in European Physical Journal C | null | 10.1140/epjc/s10052-021-08879-2 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We argue that the variational method in Wald type thought experiments,
involves order of magnitude problems when one imposes the fact that $\delta M$
is inherently a first order quantity itself. One observes that the contribution
of the second order perturbations is actually of the fourth order. Therefore
backreactions have to be explicitly calculated. Here, we re-consider the
overspinning problem for Kerr-Newman black holes interacting with test fields.
We calculate the backreaction effects due to the induced increase in the
angular velocity of the event horizon, which brings a partial solution to the
overspinning problem. To bring an ultimate solution, we argue that the
absorption probability should be taken into account in Wald type problems where
black holes interact with test fields. This fundamentally alters the course of
the analysis of the thought experiments. Due to the fact that a small fraction
of the challenging modes is absorbed by the black holes, overspinning is
prevented for both nearly extremal and extremal cases. Some extreme cases are
easily fixed by backreaction effects. The arguments do not apply to the generic
overspinning by fermionic fields for which the absorption probability is
positive definite.
| [
{
"created": "Mon, 18 Jan 2021 22:06:02 GMT",
"version": "v1"
}
] | 2021-01-21 | [
[
"Düztaş",
"Koray",
""
]
] | We argue that the variational method in Wald type thought experiments, involves order of magnitude problems when one imposes the fact that $\delta M$ is inherently a first order quantity itself. One observes that the contribution of the second order perturbations is actually of the fourth order. Therefore backreactions have to be explicitly calculated. Here, we re-consider the overspinning problem for Kerr-Newman black holes interacting with test fields. We calculate the backreaction effects due to the induced increase in the angular velocity of the event horizon, which brings a partial solution to the overspinning problem. To bring an ultimate solution, we argue that the absorption probability should be taken into account in Wald type problems where black holes interact with test fields. This fundamentally alters the course of the analysis of the thought experiments. Due to the fact that a small fraction of the challenging modes is absorbed by the black holes, overspinning is prevented for both nearly extremal and extremal cases. Some extreme cases are easily fixed by backreaction effects. The arguments do not apply to the generic overspinning by fermionic fields for which the absorption probability is positive definite. |
2111.14773 | Paolo Meda | Paolo Meda | Trace anomaly and evaporation of spherical black holes | 14 pages, 3 figure. Contribution to the Proceedings of the Sixteenth
Marcel Grossmann Meeting (MG16), July 5-10 (2021). Minor corrections added
with respect to the submitted proceeding | null | null | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The evaporation of four-dimensional spherically symmetric black holes is
presented in the framework of quantum field theory in curved spacetimes and
semiclassical gravity. It is discussed how the evaporation process can be
sourced by the presence of the trace anomaly of a massless, conformally coupled
scalar field outside the apparent horizon of the black hole.
| [
{
"created": "Mon, 29 Nov 2021 18:32:52 GMT",
"version": "v1"
}
] | 2021-11-30 | [
[
"Meda",
"Paolo",
""
]
] | The evaporation of four-dimensional spherically symmetric black holes is presented in the framework of quantum field theory in curved spacetimes and semiclassical gravity. It is discussed how the evaporation process can be sourced by the presence of the trace anomaly of a massless, conformally coupled scalar field outside the apparent horizon of the black hole. |
1002.0648 | Jun Ren | Jun Ren and Cheng-Min Zhang | Neutrino oscillations in Kerr-Newman space-time | 20 pages, no figures | Class. Quantum Grav. 27: 065011,2010 | 10.1088/0264-9381/27/6/065011 | null | gr-qc | http://creativecommons.org/licenses/by/3.0/ | The mass neutrino oscillation in Kerr-Newman(K-N) space-time is studied in
the plane $\theta=\theta_{0}$, and the general equations of oscillation phases
are given. The effect of the rotation and electric charge on the phase is
presented. Then, we consider three special cases: (1) The neutrinos travel
along the geodesics with the angular momentum $L=aE$ in the equatorial plane.
(2) The neutrinos travel along the geodesics with L=0 in the equatorial plane.
(3) The neutrinos travel along the radial geodesics at the direction
$\theta=0$. At last, we calculate the proper oscillation length in the K-N
space time. The effect of the gravitational field on the oscillation length is
embodied in the gravitational red shift factor. When the neutrino travels out
of the gravitational field, the blue shift of the oscillation length takes
place. We discussed the variation of the oscillation length influenced by the
gravitational field strength, the rotation $a^{2}$ and charge $Q$.
| [
{
"created": "Wed, 3 Feb 2010 05:35:22 GMT",
"version": "v1"
}
] | 2010-03-03 | [
[
"Ren",
"Jun",
""
],
[
"Zhang",
"Cheng-Min",
""
]
] | The mass neutrino oscillation in Kerr-Newman(K-N) space-time is studied in the plane $\theta=\theta_{0}$, and the general equations of oscillation phases are given. The effect of the rotation and electric charge on the phase is presented. Then, we consider three special cases: (1) The neutrinos travel along the geodesics with the angular momentum $L=aE$ in the equatorial plane. (2) The neutrinos travel along the geodesics with L=0 in the equatorial plane. (3) The neutrinos travel along the radial geodesics at the direction $\theta=0$. At last, we calculate the proper oscillation length in the K-N space time. The effect of the gravitational field on the oscillation length is embodied in the gravitational red shift factor. When the neutrino travels out of the gravitational field, the blue shift of the oscillation length takes place. We discussed the variation of the oscillation length influenced by the gravitational field strength, the rotation $a^{2}$ and charge $Q$. |
gr-qc/9812015 | Patrice Hello | N. Arnaud, M. Davier, F. Cavalier and P.Hello | Detection of gravitational wave bursts by interferometric detectors | 15 pages, 8 figures | Phys.Rev.D59:082002,1999 | 10.1103/PhysRevD.59.082002 | null | gr-qc | null | We study in this paper some filters for the detection of burst-like signals
in the data of interferometric gravitational-wave detectors. We present first
two general (non-linear) filters with no {\it a priori} assumption on the
waveforms to detect. A third filter, a peak correlator, is also introduced and
permits to estimate the gain, when some prior information is known about the
waveforms. We use the catalogue of supernova gravitational-wave signals built
by Zwerger and M\"uller in order to have a benchmark of the performance of each
filter and to compare to the performance of the optimal filter. The three
filters could be a part of an on-line triggering in interferometric
gravitational-wave detectors, specialised in the selection of burst events.
| [
{
"created": "Fri, 4 Dec 1998 16:21:36 GMT",
"version": "v1"
}
] | 2009-12-30 | [
[
"Arnaud",
"N.",
""
],
[
"Davier",
"M.",
""
],
[
"Cavalier",
"F.",
""
],
[
"Hello",
"P.",
""
]
] | We study in this paper some filters for the detection of burst-like signals in the data of interferometric gravitational-wave detectors. We present first two general (non-linear) filters with no {\it a priori} assumption on the waveforms to detect. A third filter, a peak correlator, is also introduced and permits to estimate the gain, when some prior information is known about the waveforms. We use the catalogue of supernova gravitational-wave signals built by Zwerger and M\"uller in order to have a benchmark of the performance of each filter and to compare to the performance of the optimal filter. The three filters could be a part of an on-line triggering in interferometric gravitational-wave detectors, specialised in the selection of burst events. |
gr-qc/9405033 | Erik A. Martinez | Erik A. Martinez | Quasilocal Energy for a Kerr black hole | 22 pages, Revtex, Alberta-Thy-18-94. (the approximations in Section
IV have been improved. To appear in Phys. Rev. D ) | Phys.Rev. D50 (1994) 4920-4928 | 10.1103/PhysRevD.50.4920 | null | gr-qc | null | The quasilocal energy associated with a constant stationary time slice of the
Kerr spacetime is presented. The calculations are based on a recent proposal
\cite{by} in which quasilocal energy is derived from the Hamiltonian of
spatially bounded gravitational systems. Three different classes of boundary
surfaces for the Kerr slice are considered (constant radius surfaces, round
spheres, and the ergosurface). Their embeddings in both the Kerr slice and flat
three-dimensional space (required as a normalization of the energy) are
analyzed. The energy contained within each surface is explicitly calculated in
the slow rotation regime and its properties discussed in detail. The energy is
a positive, monotonically decreasing function of the boundary surface radius.
It approaches the Arnowitt-Deser-Misner (ADM) mass at spatial infinity and
reduces to (twice) the irreducible mass at the horizon of the Kerr black hole.
The expressions possess the correct static limit and include negative
contributions due to gravitational binding. The energy at the ergosurface is
compared with the energies at other surfaces. Finally, the difficulties
involved in an estimation of the energy in the fast rotation regime are
discussed.
| [
{
"created": "Fri, 13 May 1994 14:45:31 GMT",
"version": "v1"
},
{
"created": "Fri, 16 Sep 1994 19:36:14 GMT",
"version": "v2"
}
] | 2009-10-22 | [
[
"Martinez",
"Erik A.",
""
]
] | The quasilocal energy associated with a constant stationary time slice of the Kerr spacetime is presented. The calculations are based on a recent proposal \cite{by} in which quasilocal energy is derived from the Hamiltonian of spatially bounded gravitational systems. Three different classes of boundary surfaces for the Kerr slice are considered (constant radius surfaces, round spheres, and the ergosurface). Their embeddings in both the Kerr slice and flat three-dimensional space (required as a normalization of the energy) are analyzed. The energy contained within each surface is explicitly calculated in the slow rotation regime and its properties discussed in detail. The energy is a positive, monotonically decreasing function of the boundary surface radius. It approaches the Arnowitt-Deser-Misner (ADM) mass at spatial infinity and reduces to (twice) the irreducible mass at the horizon of the Kerr black hole. The expressions possess the correct static limit and include negative contributions due to gravitational binding. The energy at the ergosurface is compared with the energies at other surfaces. Finally, the difficulties involved in an estimation of the energy in the fast rotation regime are discussed. |
gr-qc/9809079 | Jose Acacio de Barros | J. Acacio de Barros, N. Pinto-Neto, I. L. Shapiro | Quantum gravity correction, evolution of scalar field and inflation | 11 pages, 3 figures | Class.Quant.Grav. 16 (1999) 1773-1782 | 10.1088/0264-9381/16/6/311 | null | gr-qc hep-th | null | We take the first nontrivial coefficient of the Schwinger-DeWitt expansion as
a leading correction to the action of the second-derivative metric-dilaton
gravity. To fix the ambiguities related with an arbitrary choice of the gauge
fixing condition and the parametrization for the quantum field, one has to use
the classical equations of motion. As a result, the only corrections are the
ones to the potential of the scalar field. It turns out that the parameters of
the initial classical action may be chosen in such a way that the potential
satisfies most of the conditions for successful inflation.
| [
{
"created": "Mon, 28 Sep 1998 21:24:25 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"de Barros",
"J. Acacio",
""
],
[
"Pinto-Neto",
"N.",
""
],
[
"Shapiro",
"I. L.",
""
]
] | We take the first nontrivial coefficient of the Schwinger-DeWitt expansion as a leading correction to the action of the second-derivative metric-dilaton gravity. To fix the ambiguities related with an arbitrary choice of the gauge fixing condition and the parametrization for the quantum field, one has to use the classical equations of motion. As a result, the only corrections are the ones to the potential of the scalar field. It turns out that the parameters of the initial classical action may be chosen in such a way that the potential satisfies most of the conditions for successful inflation. |
2209.04584 | Miguel Cruz | Miguel Cruz, Samuel Lepe and Germ\'an E. Soto | Phantom cosmologies from QCD ghost dark energy | 16 pages, 1 figure. Accepted for publication in PRD | Phys. Rev. D 106, 103508 (2022) | 10.1103/PhysRevD.106.103508 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We review a dynamical dark energy model scarcely studied in the literature
and we introduce two possible generalizations. We discuss separately the
behavior of the original model and a minimal extension of it by exploring some
early and late times limits, we find that the cosmic components are related by
their parameters state. In order to have access to the phantom regime we
present two dark energy densities inspired from the holographic approach and
from the emergent entropic forces model in the early universe. For the first
case we obtain a Type III singularity and in the second proposal we have a
transition from decelerated to accelerated cosmic expansion that starts as
phantom type. However, the final stage of the universe is a de Sitter state.
| [
{
"created": "Sat, 10 Sep 2022 03:36:38 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Nov 2022 12:33:35 GMT",
"version": "v2"
}
] | 2022-11-16 | [
[
"Cruz",
"Miguel",
""
],
[
"Lepe",
"Samuel",
""
],
[
"Soto",
"Germán E.",
""
]
] | We review a dynamical dark energy model scarcely studied in the literature and we introduce two possible generalizations. We discuss separately the behavior of the original model and a minimal extension of it by exploring some early and late times limits, we find that the cosmic components are related by their parameters state. In order to have access to the phantom regime we present two dark energy densities inspired from the holographic approach and from the emergent entropic forces model in the early universe. For the first case we obtain a Type III singularity and in the second proposal we have a transition from decelerated to accelerated cosmic expansion that starts as phantom type. However, the final stage of the universe is a de Sitter state. |
gr-qc/9511048 | Evan Reidell | R. Jackiw (MIT) | Two lectures on Two-Dimensional Gravity | 23 pages in REVTeX. Talk presented at LASSF II, Caracas, Venezuela,
October 1995 | null | null | MIT-CTP-2486 | gr-qc hep-th | null | (from the talk:) I shall here speak on gravity in (1+1)-dimensional
space-time --- lineal gravity. The purpose of studying lower dimensional
theories, and specifically lower dimensional gravity, is to gain insight into
difficult conceptional issues, which are present and even more opaque in the
physical (3+1)-dimensional world. Perhaps lessons learned in the
lower-dimensional setting can be used to explicate physical problems. Moreover,
if we are lucky, the lower-dimensional theories can have a direct physical
relevance to modelling phenomena that is actually dynamically confined to the
lower dimensionality. This is what happened with (2+1)-dimensional gravity:
gravitational physics in the presence of cosmic strings (infinitely long,
perpendicular to a plane) is adequately described planar gravity. Indeed the
recently discussed causality puzzles raised by ``Gott time machines'' were
resolved with the help of the lower-dimensional model...
| [
{
"created": "Thu, 16 Nov 1995 21:47:35 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Jackiw",
"R.",
"",
"MIT"
]
] | (from the talk:) I shall here speak on gravity in (1+1)-dimensional space-time --- lineal gravity. The purpose of studying lower dimensional theories, and specifically lower dimensional gravity, is to gain insight into difficult conceptional issues, which are present and even more opaque in the physical (3+1)-dimensional world. Perhaps lessons learned in the lower-dimensional setting can be used to explicate physical problems. Moreover, if we are lucky, the lower-dimensional theories can have a direct physical relevance to modelling phenomena that is actually dynamically confined to the lower dimensionality. This is what happened with (2+1)-dimensional gravity: gravitational physics in the presence of cosmic strings (infinitely long, perpendicular to a plane) is adequately described planar gravity. Indeed the recently discussed causality puzzles raised by ``Gott time machines'' were resolved with the help of the lower-dimensional model... |
0809.3156 | Riccardo Sturani | Hillary Sanctuary and Riccardo Sturani | Effective field theory analysis of the self-interacting chameleon | 15 pages, 2 figures. Final version accepted for publication on
General Relativity and Gravitation | Gen.Rel.Grav.42:1953-1967,2010 | 10.1007/s10714-010-0974-8 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyse the phenomenology of a self-interacting scalar field in the
context of the chameleon scenario originally proposed by Khoury and Weltman. In
the absence of self-interactions, this type of scalar field can mediate long
range interactions and simultaneously evade constraints from violation of the
weak equivalence principle. By applying to such a scalar field the effective
field theory method proposed for Einstein gravity by Goldberger and Rothstein,
we give a thorough perturbative evaluation of the importance of non-derivative
self-interactions in determining the strength of the chameleon mediated force
in the case of orbital motion. The self-interactions are potentially dangerous
as they can change the long range behaviour of the field. Nevertheless, we show
that they do not lead to any dramatic phenomenological consequence with respect
to the linear case and solar system constraints are fulfilled.
| [
{
"created": "Thu, 18 Sep 2008 13:27:43 GMT",
"version": "v1"
},
{
"created": "Mon, 12 Apr 2010 11:19:01 GMT",
"version": "v2"
}
] | 2014-11-18 | [
[
"Sanctuary",
"Hillary",
""
],
[
"Sturani",
"Riccardo",
""
]
] | We analyse the phenomenology of a self-interacting scalar field in the context of the chameleon scenario originally proposed by Khoury and Weltman. In the absence of self-interactions, this type of scalar field can mediate long range interactions and simultaneously evade constraints from violation of the weak equivalence principle. By applying to such a scalar field the effective field theory method proposed for Einstein gravity by Goldberger and Rothstein, we give a thorough perturbative evaluation of the importance of non-derivative self-interactions in determining the strength of the chameleon mediated force in the case of orbital motion. The self-interactions are potentially dangerous as they can change the long range behaviour of the field. Nevertheless, we show that they do not lead to any dramatic phenomenological consequence with respect to the linear case and solar system constraints are fulfilled. |
1711.02973 | Giulia Gubitosi | Giulia Gubitosi, Joao Magueijo | Squeezing of scalar and tensor primordial perturbations generated by
modified dispersion relations | null | Phys. Rev. D 97, 063502 (2018) | 10.1103/PhysRevD.97.063502 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In recent work we analyzed the evolution of primordial perturbations
satisfying Planck-scale-modified dispersion relations and showed that there is
no cosmological "squeezing" in the critical model that produces perturbations
with a scale invariant spectrum. Nevertheless, the perturbations reenter the
horizon as standing waves with the correct temporal phase because of the
late-time decay of the momentum mode. Here we shed light on the absence of
primordial squeezing by re-examining the problem in the dual rainbow frame,
where $c$ is set to 1, shifting the varying $c$ effects elsewhere. In this
frame gravity switches off at sub-Planckian wavelengths, so that the
fluctuations behave as if they were in Minkowski spacetime. This is ultimately
why they are not squeezed. However, away from the critical model squeezing does
occur if the fluctuations spectrum is red, as is the case for scalar
perturbations. Should the primordial gravity waves have a blue spectrum, we
predict that they might not reenter the horizon as standing waves, because the
momentum mode would be enhanced in the primordial phase.
| [
{
"created": "Wed, 8 Nov 2017 14:41:54 GMT",
"version": "v1"
}
] | 2018-03-07 | [
[
"Gubitosi",
"Giulia",
""
],
[
"Magueijo",
"Joao",
""
]
] | In recent work we analyzed the evolution of primordial perturbations satisfying Planck-scale-modified dispersion relations and showed that there is no cosmological "squeezing" in the critical model that produces perturbations with a scale invariant spectrum. Nevertheless, the perturbations reenter the horizon as standing waves with the correct temporal phase because of the late-time decay of the momentum mode. Here we shed light on the absence of primordial squeezing by re-examining the problem in the dual rainbow frame, where $c$ is set to 1, shifting the varying $c$ effects elsewhere. In this frame gravity switches off at sub-Planckian wavelengths, so that the fluctuations behave as if they were in Minkowski spacetime. This is ultimately why they are not squeezed. However, away from the critical model squeezing does occur if the fluctuations spectrum is red, as is the case for scalar perturbations. Should the primordial gravity waves have a blue spectrum, we predict that they might not reenter the horizon as standing waves, because the momentum mode would be enhanced in the primordial phase. |
1102.2857 | Jonathan Thornburg | Jonathan Thornburg | The Capra Research Program for Modelling Extreme Mass Ratio Inspirals | 29 pages, 4 figures, invited review to appear in GW Notes
(http://brownbag.lisascience.org/lisa-gw-notes/) | null | null | null | gr-qc astro-ph.CO astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Suppose a small compact object (black hole or neutron star) of mass $m$
orbits a large black hole of mass $M \gg m$. This system emits gravitational
waves (GWs) that have a radiation-reaction effect on the particle's motion.
EMRIs (extreme--mass-ratio inspirals) of this type will be important GW sources
for LISA; LISA's data analysis will require highly accurate EMRI GW templates.
In this article I outline the "Capra" research program to try to model EMRIs
and calculate their GWs \textit{ab initio}, assuming only that $m \ll M$ and
that the Einstein equations hold. Here we treat the EMRI spacetime as a
perturbation of the large black hole's "background" (Schwarzschild or Kerr)
spacetime and use the methods of black-hole perturbation theory, expanding in
the small parameter $m/M$. The small body's motion can be described either as
the result of a radiation-reaction "self-force" acting in the background
spacetime or as geodesic motion in a perturbed spacetime. Several different
lines of reasoning lead to the (same) basic $\O(m/M)$ "MiSaTaQuWa" equations of
motion for the particle. Surprisingly, for a nonlinear field theory such as
general relativity, modelling the small body as a point particle works well.
The particle's own field is singular along the particle worldline so it's
difficult to formulate a meaningful "perturbation" theory or equations of
motion there. I discuss "mode-sum" and "puncture-function" regularization
schemes that resolve this difficulty and allow practical self-force
calculations, and I outline an important recent calculation of this type.
Most Capra research to date has used 1st order perturbation theory. To obtain
the very high accuracies needed to fully exploit LISA's observations of the
strongest EMRIs, 2nd order perturbation theory will probably be needed.
| [
{
"created": "Mon, 14 Feb 2011 19:06:38 GMT",
"version": "v1"
}
] | 2011-02-15 | [
[
"Thornburg",
"Jonathan",
""
]
] | Suppose a small compact object (black hole or neutron star) of mass $m$ orbits a large black hole of mass $M \gg m$. This system emits gravitational waves (GWs) that have a radiation-reaction effect on the particle's motion. EMRIs (extreme--mass-ratio inspirals) of this type will be important GW sources for LISA; LISA's data analysis will require highly accurate EMRI GW templates. In this article I outline the "Capra" research program to try to model EMRIs and calculate their GWs \textit{ab initio}, assuming only that $m \ll M$ and that the Einstein equations hold. Here we treat the EMRI spacetime as a perturbation of the large black hole's "background" (Schwarzschild or Kerr) spacetime and use the methods of black-hole perturbation theory, expanding in the small parameter $m/M$. The small body's motion can be described either as the result of a radiation-reaction "self-force" acting in the background spacetime or as geodesic motion in a perturbed spacetime. Several different lines of reasoning lead to the (same) basic $\O(m/M)$ "MiSaTaQuWa" equations of motion for the particle. Surprisingly, for a nonlinear field theory such as general relativity, modelling the small body as a point particle works well. The particle's own field is singular along the particle worldline so it's difficult to formulate a meaningful "perturbation" theory or equations of motion there. I discuss "mode-sum" and "puncture-function" regularization schemes that resolve this difficulty and allow practical self-force calculations, and I outline an important recent calculation of this type. Most Capra research to date has used 1st order perturbation theory. To obtain the very high accuracies needed to fully exploit LISA's observations of the strongest EMRIs, 2nd order perturbation theory will probably be needed. |
2002.02501 | Nathaniel Strauss | Nathaniel A. Strauss, Bernard F. Whiting, and Anne T. Franzen | Classical Tools for Antipodal Identification in Reissner-Nordstr\"om
Spacetime | 35 pages, 17 figures | Class. Quant. Grav. 37 (2020) 18, 185006 | 10.1088/1361-6382/ab9a9d | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We extend the discussion of the antipodal identification of black holes to
the Reissner-Nordstr\"om (RN) spacetime by developing the classical tools
necessary to define the corresponding quantum field theory (QFT). We solve the
massless Klein-Gordon equation in the RN background in terms of scattering
coefficients and provide a procedure for constructing a solution for an
arbitrary analytic extension of RN. The behavior of the maximally extended
solution is highly dependent upon the coefficients of scattering between the
inner and outer horizons, so we present the low-frequency behavior of, and
numerical solutions for, these quantities. We find that, for low enough
frequency, field amplitudes of solutions with purely positive or negative
frequency at each horizon will acquire only a phase after passing both the
inner and outer horizons, while at higher frequencies the amplitudes will tend
to grow exponentially either to the future or to the past, and decay
exponentially in the other direction. Regardless, we can always construct a
basis of globally antipodal symmetric and antisymmetric solutions for any
finite analytic extension of RN. We have characterized this basis in terms of
positive and negative frequency solutions for future use in constructing the
corresponding QFT.
| [
{
"created": "Thu, 6 Feb 2020 20:20:37 GMT",
"version": "v1"
},
{
"created": "Sat, 22 Feb 2020 00:36:23 GMT",
"version": "v2"
},
{
"created": "Sun, 20 Sep 2020 19:58:33 GMT",
"version": "v3"
}
] | 2020-09-22 | [
[
"Strauss",
"Nathaniel A.",
""
],
[
"Whiting",
"Bernard F.",
""
],
[
"Franzen",
"Anne T.",
""
]
] | We extend the discussion of the antipodal identification of black holes to the Reissner-Nordstr\"om (RN) spacetime by developing the classical tools necessary to define the corresponding quantum field theory (QFT). We solve the massless Klein-Gordon equation in the RN background in terms of scattering coefficients and provide a procedure for constructing a solution for an arbitrary analytic extension of RN. The behavior of the maximally extended solution is highly dependent upon the coefficients of scattering between the inner and outer horizons, so we present the low-frequency behavior of, and numerical solutions for, these quantities. We find that, for low enough frequency, field amplitudes of solutions with purely positive or negative frequency at each horizon will acquire only a phase after passing both the inner and outer horizons, while at higher frequencies the amplitudes will tend to grow exponentially either to the future or to the past, and decay exponentially in the other direction. Regardless, we can always construct a basis of globally antipodal symmetric and antisymmetric solutions for any finite analytic extension of RN. We have characterized this basis in terms of positive and negative frequency solutions for future use in constructing the corresponding QFT. |
gr-qc/9702060 | null | H.Balasin | Distributional energy momentum tensor of the extended Kerr geometry | 12 pages, latex2e, amslatex and epsf macros | Class.Quant.Grav. 14 (1997) 3353-3362 | 10.1088/0264-9381/14/12/018 | TUW97-03 | gr-qc | null | We generalize previous work on the energy-momentum tensor-distribution of the
Kerr geometry by extending the manifold structure into the negative mass
region. Since the extension of the flat part of the Kerr-Schild decomposition
from one sheet to the double cover develops a singularity at the branch surface
we have to take its non-smoothness into account. It is however possible to find
a geometry within the generalized Kerr-Schild class that is in the
Colombeau-sense associated to the maximally analytic Kerr-metric.
| [
{
"created": "Thu, 27 Feb 1997 23:01:32 GMT",
"version": "v1"
}
] | 2009-10-30 | [
[
"Balasin",
"H.",
""
]
] | We generalize previous work on the energy-momentum tensor-distribution of the Kerr geometry by extending the manifold structure into the negative mass region. Since the extension of the flat part of the Kerr-Schild decomposition from one sheet to the double cover develops a singularity at the branch surface we have to take its non-smoothness into account. It is however possible to find a geometry within the generalized Kerr-Schild class that is in the Colombeau-sense associated to the maximally analytic Kerr-metric. |
2107.04848 | Yu-Xiao Liu | Yu-Peng Zhang, Yan-Bo Zeng, Yong-Qiang Wang, Shao-Wen Wei, and Yu-Xiao
Liu | Motion of test particle in rotating boson star | 17 pages, 16 figures | Phys. Rev. D 105 (2022) 044021 | 10.1103/PhysRevD.105.044021 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Motion of a test particle plays an important role in understanding the
properties of a spacetime. As a new type of the strong gravity system, boson
stars could mimic black holes located at the center of galaxies. Studying the
motion of a test particle in the spacetime of a rotating boson star will
provide the astrophysical observable effects if a boson star is located at the
center of a galaxy. In this paper, we investigate the timelike geodesic of a
test particle in the background of a rotating boson star with angular number
$m=(1, 2, 3)$. With the change of angular number and frequency, a rotating
boson star will transform from the low rotating state to the highly
relativistic rapidly rotating state, the corresponding Lense-Thirring effects
will be more and more significant and it should be studied in detail. By
solving the four-velocity of a test particle and integrating the geodesics, we
investigate the bound orbits with a zero and nonzero angular momentum. We find
that a test particle can stay more longer time in the central region of a boson
star when the boson star becomes from low rotating state to highly relativistic
rotating state. Comparing the periapse values of the orbits obtained in
rotating boson stars and the corresponding orbits of the observed stars
orbiting Sagittarius $A^*$, we discuss the possible observable effects of the
astrophysical boson star in the Galactic center.
| [
{
"created": "Sat, 10 Jul 2021 14:34:27 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Apr 2022 16:13:19 GMT",
"version": "v2"
}
] | 2024-02-26 | [
[
"Zhang",
"Yu-Peng",
""
],
[
"Zeng",
"Yan-Bo",
""
],
[
"Wang",
"Yong-Qiang",
""
],
[
"Wei",
"Shao-Wen",
""
],
[
"Liu",
"Yu-Xiao",
""
]
] | Motion of a test particle plays an important role in understanding the properties of a spacetime. As a new type of the strong gravity system, boson stars could mimic black holes located at the center of galaxies. Studying the motion of a test particle in the spacetime of a rotating boson star will provide the astrophysical observable effects if a boson star is located at the center of a galaxy. In this paper, we investigate the timelike geodesic of a test particle in the background of a rotating boson star with angular number $m=(1, 2, 3)$. With the change of angular number and frequency, a rotating boson star will transform from the low rotating state to the highly relativistic rapidly rotating state, the corresponding Lense-Thirring effects will be more and more significant and it should be studied in detail. By solving the four-velocity of a test particle and integrating the geodesics, we investigate the bound orbits with a zero and nonzero angular momentum. We find that a test particle can stay more longer time in the central region of a boson star when the boson star becomes from low rotating state to highly relativistic rotating state. Comparing the periapse values of the orbits obtained in rotating boson stars and the corresponding orbits of the observed stars orbiting Sagittarius $A^*$, we discuss the possible observable effects of the astrophysical boson star in the Galactic center. |
1306.5784 | Alcides Garat | Alcides Garat | The Monopole and the Coulomb field as duals within the unifying
Reissner-Nordstrom geometry | 10 pages. arXiv admin note: substantial text overlap with
arXiv:1306.0602, arXiv:1306.4005, arXiv:1306.2174 | Commun.Theor.Phys. 61 (2014) 699-702 | 10.1088/0253-6102/61/6/07 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We are going to prove that the Monopole and the Coulomb fields are duals
within the unifying structure provided by the Reissner-Nordstrom spacetime.
This is accomplished when noticing that in order to produce the tetrad that
locally and covariantly diagonalizes the stress-energy tensor, both the
Monopole and the Coulomb fields are necessary in the construction. Without any
of them it would be impossible to express the tetrad vectors that locally and
covariantly diagonalize the stress-energy tensor. Then, both electromagnetic
fields are an integral part of the same structure, the Reissner-Nordstrom
geometry.
| [
{
"created": "Mon, 24 Jun 2013 21:07:25 GMT",
"version": "v1"
}
] | 2024-07-16 | [
[
"Garat",
"Alcides",
""
]
] | We are going to prove that the Monopole and the Coulomb fields are duals within the unifying structure provided by the Reissner-Nordstrom spacetime. This is accomplished when noticing that in order to produce the tetrad that locally and covariantly diagonalizes the stress-energy tensor, both the Monopole and the Coulomb fields are necessary in the construction. Without any of them it would be impossible to express the tetrad vectors that locally and covariantly diagonalize the stress-energy tensor. Then, both electromagnetic fields are an integral part of the same structure, the Reissner-Nordstrom geometry. |
gr-qc/0301073 | Piotr Chrusciel | Piotr T. Chrusciel, Erwann Delay | On mapping properties of the general relativistic constraints operator
in weighted function spaces, with applications | latex2e, now 87 pages, several style files; various typos corrected,
treatment of weighted Hoelder spaces improved, to appear in Memoires de la
Societe Mathematique de France | Mem.Soc.Math.France 94 (2003) 1-103 | null | null | gr-qc | null | Generalising an analysis of Corvino and Schoen, we study surjectivity
properties of the constraint map in general relativity in a large class of
weighted Sobolev spaces. As a corollary we prove several perturbation, gluing,
and extension results: we show existence of non-trivial, singularity-free,
vacuum space-times which are stationary in a neighborhood of $i^0$; for small
perturbations of parity-covariant initial data sufficiently close to those for
Minkowski space-time this leads to space-times with a smooth global Scri; we
prove existence of initial data for many black holes which are exactly Kerr --
or exactly Schwarzschild -- both near infinity and near each of the connected
components of the apparent horizon; under appropriate conditions we obtain
existence of vacuum extensions of vacuum initial data across compact
boundaries; we show that for generic metrics the deformations in the
Isenberg-Mazzeo-Pollack gluings can be localised, so that the initial data on
the connected sum manifold coincide with the original ones except for a small
neighborhood of the gluing region; we prove existence of asymptotically flat
solutions which are static or stationary up to $r^{-m}$ terms, for any fixed
$m$, and with multipole moments freely prescribable within certain ranges.
| [
{
"created": "Tue, 21 Jan 2003 07:44:14 GMT",
"version": "v1"
},
{
"created": "Fri, 11 Jul 2003 08:26:03 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Chrusciel",
"Piotr T.",
""
],
[
"Delay",
"Erwann",
""
]
] | Generalising an analysis of Corvino and Schoen, we study surjectivity properties of the constraint map in general relativity in a large class of weighted Sobolev spaces. As a corollary we prove several perturbation, gluing, and extension results: we show existence of non-trivial, singularity-free, vacuum space-times which are stationary in a neighborhood of $i^0$; for small perturbations of parity-covariant initial data sufficiently close to those for Minkowski space-time this leads to space-times with a smooth global Scri; we prove existence of initial data for many black holes which are exactly Kerr -- or exactly Schwarzschild -- both near infinity and near each of the connected components of the apparent horizon; under appropriate conditions we obtain existence of vacuum extensions of vacuum initial data across compact boundaries; we show that for generic metrics the deformations in the Isenberg-Mazzeo-Pollack gluings can be localised, so that the initial data on the connected sum manifold coincide with the original ones except for a small neighborhood of the gluing region; we prove existence of asymptotically flat solutions which are static or stationary up to $r^{-m}$ terms, for any fixed $m$, and with multipole moments freely prescribable within certain ranges. |
1301.3918 | Niels Warburton | Niels Warburton, Leor Barack, Norichika Sago | Isofrequency pairing of geodesic orbits in Kerr geometry | 11 pages, 8 figures. Updated to reflect published version | Phys. Rev. D 87, 084012 (2013) | 10.1103/PhysRevD.87.084012 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Bound geodesic orbits around a Kerr black hole can be parametrized by three
constants of the motion: the (specific) orbital energy, angular momentum and
Carter constant. Generically, each orbit also has associated with it three
frequencies, related to the radial, longitudinal and (mean) azimuthal motions.
Here we note the curious fact that these two ways of characterizing bound
geodesics are not in a one-to-one correspondence. While the former uniquely
specifies an orbit up to initial conditions, the latter does not: there is a
(strong-field) region of the parameter space in which pairs of physically
distinct orbits can have the same three frequencies. In each such isofrequency
pair the two orbits exhibit the same rate of periastron precession and the same
rate of Lense-Thirring precession of the orbital plane, and (in a certain
sense) they remain "synchronized" in phase.
| [
{
"created": "Wed, 16 Jan 2013 21:04:16 GMT",
"version": "v1"
},
{
"created": "Fri, 5 Apr 2013 18:55:24 GMT",
"version": "v2"
}
] | 2013-05-29 | [
[
"Warburton",
"Niels",
""
],
[
"Barack",
"Leor",
""
],
[
"Sago",
"Norichika",
""
]
] | Bound geodesic orbits around a Kerr black hole can be parametrized by three constants of the motion: the (specific) orbital energy, angular momentum and Carter constant. Generically, each orbit also has associated with it three frequencies, related to the radial, longitudinal and (mean) azimuthal motions. Here we note the curious fact that these two ways of characterizing bound geodesics are not in a one-to-one correspondence. While the former uniquely specifies an orbit up to initial conditions, the latter does not: there is a (strong-field) region of the parameter space in which pairs of physically distinct orbits can have the same three frequencies. In each such isofrequency pair the two orbits exhibit the same rate of periastron precession and the same rate of Lense-Thirring precession of the orbital plane, and (in a certain sense) they remain "synchronized" in phase. |
0705.3098 | Jiri Podolsky | Jiri Podolsky, David Kofron | Chaotic motion in Kundt spacetimes | 15 pages, 9 figures. To appear in Classical and Quantum Gravity | Class.Quant.Grav.24:3413-3424,2007 | 10.1088/0264-9381/24/13/016 | null | gr-qc | null | We demonstrate that geodesics in exact vacuum Kundt gravitational waves may
exhibit a highly complicated behaviour. In fact, as in the previously studied
case of non-homogeneous pp-waves, for specific choices of the structural
function the motion appears to be genuinely chaotic. This fact is demonstrated
by the fractal method.
| [
{
"created": "Tue, 22 May 2007 07:04:19 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Podolsky",
"Jiri",
""
],
[
"Kofron",
"David",
""
]
] | We demonstrate that geodesics in exact vacuum Kundt gravitational waves may exhibit a highly complicated behaviour. In fact, as in the previously studied case of non-homogeneous pp-waves, for specific choices of the structural function the motion appears to be genuinely chaotic. This fact is demonstrated by the fractal method. |
gr-qc/0203092 | Esposito Giampiero | Giampiero Esposito and Cosimo Stornaiolo | On the Riemann Function and Irregular Singular Points for Axisymmetric
Black Hole Collisions at the Speed of Light | 13 pages, plain Tex | null | null | DSF preprint 2002/7 | gr-qc | null | The news function providing some relevant information about angular
distribution of gravitational radiation in axisymmetric black hole collisions
at the speed of light had been evaluated in the literature by perturbation
methods, after inverting second-order hyperbolic operators with variable
coefficients in two independent variables. More recent work has related the
appropriate Green function to the Riemann function for such a class of
hyperbolic operators in two variables. The present paper obtains an improvement
in the evaluation of the coefficients occurring in the second-order equation
obeyed by the Riemann function, which might prove useful for numerical
purposes. Eventually, we find under which conditions the original
Green-function calculation reduces to finding solutions of an inhomogeneous
second-order ordinary differential equation with a non-regular singular point.
| [
{
"created": "Tue, 26 Mar 2002 13:05:14 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Esposito",
"Giampiero",
""
],
[
"Stornaiolo",
"Cosimo",
""
]
] | The news function providing some relevant information about angular distribution of gravitational radiation in axisymmetric black hole collisions at the speed of light had been evaluated in the literature by perturbation methods, after inverting second-order hyperbolic operators with variable coefficients in two independent variables. More recent work has related the appropriate Green function to the Riemann function for such a class of hyperbolic operators in two variables. The present paper obtains an improvement in the evaluation of the coefficients occurring in the second-order equation obeyed by the Riemann function, which might prove useful for numerical purposes. Eventually, we find under which conditions the original Green-function calculation reduces to finding solutions of an inhomogeneous second-order ordinary differential equation with a non-regular singular point. |
1503.05164 | Alexander Grant | Alexander Grant, Eanna E. Flanagan | Non-conservation of Carter in black hole spacetimes | 5 pages, 1 figure, (v2) typos corrected, some clarifications and
appendix B added | null | 10.1088/0264-9381/32/15/157001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Freely falling point particles in the vicinity of Kerr black holes are
subject to a conservation law, that of their Carter constant. We consider the
conjecture that this conservation law is a special case of a more general
conservation law, valid for arbitrary processes obeying local energy momentum
conservation. Under some fairly general assumptions we prove that the
conjecture is false: there is no conservation law for conserved stress-energy
tensors on the Kerr background that reduces to conservation of Carter for a
single point particle.
| [
{
"created": "Tue, 17 Mar 2015 18:55:28 GMT",
"version": "v1"
},
{
"created": "Tue, 16 Jun 2015 19:42:24 GMT",
"version": "v2"
}
] | 2015-08-06 | [
[
"Grant",
"Alexander",
""
],
[
"Flanagan",
"Eanna E.",
""
]
] | Freely falling point particles in the vicinity of Kerr black holes are subject to a conservation law, that of their Carter constant. We consider the conjecture that this conservation law is a special case of a more general conservation law, valid for arbitrary processes obeying local energy momentum conservation. Under some fairly general assumptions we prove that the conjecture is false: there is no conservation law for conserved stress-energy tensors on the Kerr background that reduces to conservation of Carter for a single point particle. |
gr-qc/0702086 | Francisco Navarro-Lerida | Jutta Kunz, Francisco Navarro-Lerida, and Eugen Radu | Higher dimensional rotating black holes in Einstein-Maxwell theory with
negative cosmological constant | 11 pages, 8 figures | Phys.Lett.B649:463-471,2007 | 10.1016/j.physletb.2007.04.030 | null | gr-qc hep-th | null | We present arguments for the existence of charged, rotating black holes with
equal-magnitude angular momenta in an odd number of dimensions $D\geq 5$. These
solutions posses a regular horizon of spherical topology and approach
asymptotically the Anti-de Sitter spacetime background. We analyze their global
charges, their gyromagnetic ratio and their horizon properties.
| [
{
"created": "Thu, 15 Feb 2007 10:11:51 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Kunz",
"Jutta",
""
],
[
"Navarro-Lerida",
"Francisco",
""
],
[
"Radu",
"Eugen",
""
]
] | We present arguments for the existence of charged, rotating black holes with equal-magnitude angular momenta in an odd number of dimensions $D\geq 5$. These solutions posses a regular horizon of spherical topology and approach asymptotically the Anti-de Sitter spacetime background. We analyze their global charges, their gyromagnetic ratio and their horizon properties. |
0902.0790 | Harald P. Pfeiffer | Alessandra Buonanno, Yi Pan, Harald P. Pfeiffer, Mark A. Scheel, Luisa
T. Buchman, Lawrence E. Kidder | Effective-one-body waveforms calibrated to numerical relativity
simulations: coalescence of non-spinning, equal-mass black holes | 19 pages, 19 figures. Two improvements to our analytical model:
non-quasi-circular correction based on post-Newtonian theory and hybrid comb
matching to attach ring-down modes. No substantial modification to any
results. Figures and numbers are slightly changed, accordingly. Corrected a
few typos and added a few references | Phys.Rev.D79:124028,2009 | 10.1103/PhysRevD.79.124028 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We calibrate the effective-one-body (EOB) model to an accurate numerical
simulation of an equal-mass, non-spinning binary black-hole coalescence
produced by the Caltech-Cornell collaboration. Aligning the EOB and numerical
waveforms at low frequency over a time interval of ~1000M, and taking into
account the uncertainties in the numerical simulation, we investigate the
significance and degeneracy of the EOB adjustable parameters during inspiral,
plunge and merger, and determine the minimum number of EOB adjustable
parameters that achieves phase and amplitude agreements on the order of the
numerical error. We find that phase and fractional amplitude differences
between the numerical and EOB values of the dominant gravitational wave mode
h_{22} can be reduced to 0.02 radians and 2%, respectively, until a time 26 M
before merger, and to 0.1 radians and 10%, at a time 16M after merger (during
ringdown), respectively. Using LIGO, Enhanced LIGO and Advanced LIGO noise
curves, we find that the overlap between the EOB and the numerical h_{22},
maximized only over the initial phase and time of arrival, is larger than 0.999
for equal-mass binary black holes with total mass 30-150 Msun. In addition to
the leading gravitational mode (2,2), we compare the dominant subleading modes
(4,4) and (3,2) and find phase and amplitude differences on the order of the
numerical error. We also determine the mass-ratio dependence of one of the EOB
adjustable parameters by fitting to numerical {\it inspiral} waveforms for
black-hole binaries with mass ratios 2:1 and 3:1. These results improve and
extend recent successful attempts aimed at providing gravitational-wave data
analysts the best analytical EOB model capable of interpolating accurate
numerical simulations.
| [
{
"created": "Wed, 4 Feb 2009 20:51:32 GMT",
"version": "v1"
},
{
"created": "Tue, 12 May 2009 02:37:09 GMT",
"version": "v2"
}
] | 2009-08-03 | [
[
"Buonanno",
"Alessandra",
""
],
[
"Pan",
"Yi",
""
],
[
"Pfeiffer",
"Harald P.",
""
],
[
"Scheel",
"Mark A.",
""
],
[
"Buchman",
"Luisa T.",
""
],
[
"Kidder",
"Lawrence E.",
""
]
] | We calibrate the effective-one-body (EOB) model to an accurate numerical simulation of an equal-mass, non-spinning binary black-hole coalescence produced by the Caltech-Cornell collaboration. Aligning the EOB and numerical waveforms at low frequency over a time interval of ~1000M, and taking into account the uncertainties in the numerical simulation, we investigate the significance and degeneracy of the EOB adjustable parameters during inspiral, plunge and merger, and determine the minimum number of EOB adjustable parameters that achieves phase and amplitude agreements on the order of the numerical error. We find that phase and fractional amplitude differences between the numerical and EOB values of the dominant gravitational wave mode h_{22} can be reduced to 0.02 radians and 2%, respectively, until a time 26 M before merger, and to 0.1 radians and 10%, at a time 16M after merger (during ringdown), respectively. Using LIGO, Enhanced LIGO and Advanced LIGO noise curves, we find that the overlap between the EOB and the numerical h_{22}, maximized only over the initial phase and time of arrival, is larger than 0.999 for equal-mass binary black holes with total mass 30-150 Msun. In addition to the leading gravitational mode (2,2), we compare the dominant subleading modes (4,4) and (3,2) and find phase and amplitude differences on the order of the numerical error. We also determine the mass-ratio dependence of one of the EOB adjustable parameters by fitting to numerical {\it inspiral} waveforms for black-hole binaries with mass ratios 2:1 and 3:1. These results improve and extend recent successful attempts aimed at providing gravitational-wave data analysts the best analytical EOB model capable of interpolating accurate numerical simulations. |
0803.0390 | Donato Bini | Donato Bini, Christian Cherubini, Carmen Chicone, Bahram Mashhoon | Gravitational induction | Slightly expanded version | Class.Quant.Grav.25:225014,2008 | 10.1088/0264-9381/25/22/225014 | null | gr-qc astro-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the linear post-Newtonian approximation to general relativity known
as gravitoelectromagnetism (GEM); in particular, we examine the similarities
and differences between GEM and electrodynamics. Notwithstanding some
significant differences between them, we find that a special nonstationary
metric in GEM can be employed to show {\it explicitly} that it is possible to
introduce gravitational induction within GEM in close analogy with Faraday's
law of induction and Lenz's law in electrodynamics. Some of the physical
implications of gravitational induction are briefly discussed.
| [
{
"created": "Tue, 4 Mar 2008 09:00:21 GMT",
"version": "v1"
},
{
"created": "Mon, 3 Nov 2008 09:09:15 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Bini",
"Donato",
""
],
[
"Cherubini",
"Christian",
""
],
[
"Chicone",
"Carmen",
""
],
[
"Mashhoon",
"Bahram",
""
]
] | We study the linear post-Newtonian approximation to general relativity known as gravitoelectromagnetism (GEM); in particular, we examine the similarities and differences between GEM and electrodynamics. Notwithstanding some significant differences between them, we find that a special nonstationary metric in GEM can be employed to show {\it explicitly} that it is possible to introduce gravitational induction within GEM in close analogy with Faraday's law of induction and Lenz's law in electrodynamics. Some of the physical implications of gravitational induction are briefly discussed. |
gr-qc/0502053 | Eugen Radu | Yves Brihaye and Eugen Radu | Nutty dyons | 12 pages, 4 figures, discussion extended, typos corrected | Phys.Lett. B615 (2005) 1-13 | 10.1016/j.physletb.2005.04.016 | null | gr-qc hep-th | null | We argue that the Einstein-Yang-Mills-Higgs theory presents nontrivial
solutions with a NUT charge. These solutions approach asymptotically the
Taub-NUT spacetime and generalize the known dyon black hole configurations. The
main properties of the solutions and the differences with respect to the
asymptotically flat case are discussed. We find that a nonabelian magnetic
monopole placed in the field of gravitational dyon necessarily acquires an
electric field, while the magnetic charge may take arbitrary values.
| [
{
"created": "Fri, 11 Feb 2005 12:11:07 GMT",
"version": "v1"
},
{
"created": "Wed, 6 Apr 2005 09:09:24 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Brihaye",
"Yves",
""
],
[
"Radu",
"Eugen",
""
]
] | We argue that the Einstein-Yang-Mills-Higgs theory presents nontrivial solutions with a NUT charge. These solutions approach asymptotically the Taub-NUT spacetime and generalize the known dyon black hole configurations. The main properties of the solutions and the differences with respect to the asymptotically flat case are discussed. We find that a nonabelian magnetic monopole placed in the field of gravitational dyon necessarily acquires an electric field, while the magnetic charge may take arbitrary values. |
gr-qc/9311004 | Hugh Luckock | R. Graham and H. Luckock | The Hartle-Hawking state for the Bianchi IX model in supergravity | 9 pages, University of Sydney Mathematics Report 93-50 | Phys.Rev.D49:4981-4984,1994 | 10.1103/PhysRevD.49.R4981 | null | gr-qc | null | We solve the quantum constraints for homogeneous N=1 supergravity on
3-geometries with a Bianchi IX metric. Because these geometries admit Killing
vectors with the same commutation relations as the angular momentum generators,
there are two distinct definitions of homogeneity. The first of these is
well-known and has been shown by D'Eath to give the wormhole state. We show
that the alternative definition of homogeneity leads to the Hartle-Hawking ``no
boundary" state.
| [
{
"created": "Thu, 4 Nov 1993 00:23:32 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Nov 1993 23:17:35 GMT",
"version": "v2"
}
] | 2010-01-06 | [
[
"Graham",
"R.",
""
],
[
"Luckock",
"H.",
""
]
] | We solve the quantum constraints for homogeneous N=1 supergravity on 3-geometries with a Bianchi IX metric. Because these geometries admit Killing vectors with the same commutation relations as the angular momentum generators, there are two distinct definitions of homogeneity. The first of these is well-known and has been shown by D'Eath to give the wormhole state. We show that the alternative definition of homogeneity leads to the Hartle-Hawking ``no boundary" state. |
2203.11459 | Chandrachur Chakraborty | Chandrachur Chakraborty (IISc / MCNS-MAHE), Banibrata Mukhopadhyay
(IISc) | Spin precession in the gravity wave analogue black hole spacetime | 12 pages including 4 figures; Version published in Universe | Universe 8, 193 (2022) | 10.3390/universe8030193 | null | gr-qc astro-ph.HE cond-mat.other physics.flu-dyn | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It was predicted that the spin precession frequency of a stationary gyroscope
shows various anomalies in the strong gravity regime if its orbit shrinks, and
eventually its precession frequency becomes arbitrarily high very close to the
horizon of a rotating black hole. Considering the gravity waves of a flowing
fluid with vortex in a shallow basin, that acts as a rotating analogue black
hole, one can observe the predicted strong gravity effect on the spin
precession in the laboratory. Attaching a thread with the buoyant particles and
anchored it to the bottom of the fluid container with a short length of
miniature chain, one can construct a simple local test gyroscope to measure the
spin precession frequency in the vicinity of the gravity wave analogue black
hole. The thread acts as the axis of the gyroscope. By regulating the orbital
frequency of the test gyroscope, one can also be able to measure the strong
gravity Lense-Thirring effect and geodetic/de-Sitter effect with this
experimental set-up, as the special cases. For example, to measure the
Lense-Thirring effect, the length of the miniature chain can be set to zero, so
that the gyroscope becomes static. One can also measure the geodetic precession
with this system by orbiting the test gyroscope in the so-called Keplerian
frequency around the non-rotating analogue black hole that can be constructed
by making the rotation of the fluid/vortex negligible compared to its radial
velocity.
| [
{
"created": "Tue, 22 Mar 2022 04:50:17 GMT",
"version": "v1"
}
] | 2022-03-24 | [
[
"Chakraborty",
"Chandrachur",
"",
"IISc / MCNS-MAHE"
],
[
"Mukhopadhyay",
"Banibrata",
"",
"IISc"
]
] | It was predicted that the spin precession frequency of a stationary gyroscope shows various anomalies in the strong gravity regime if its orbit shrinks, and eventually its precession frequency becomes arbitrarily high very close to the horizon of a rotating black hole. Considering the gravity waves of a flowing fluid with vortex in a shallow basin, that acts as a rotating analogue black hole, one can observe the predicted strong gravity effect on the spin precession in the laboratory. Attaching a thread with the buoyant particles and anchored it to the bottom of the fluid container with a short length of miniature chain, one can construct a simple local test gyroscope to measure the spin precession frequency in the vicinity of the gravity wave analogue black hole. The thread acts as the axis of the gyroscope. By regulating the orbital frequency of the test gyroscope, one can also be able to measure the strong gravity Lense-Thirring effect and geodetic/de-Sitter effect with this experimental set-up, as the special cases. For example, to measure the Lense-Thirring effect, the length of the miniature chain can be set to zero, so that the gyroscope becomes static. One can also measure the geodetic precession with this system by orbiting the test gyroscope in the so-called Keplerian frequency around the non-rotating analogue black hole that can be constructed by making the rotation of the fluid/vortex negligible compared to its radial velocity. |
gr-qc/0205047 | Patrizia Vitale | F. Canfora, G. Vilasi and P. Vitale | Nonlinear gravitational waves and their polarization | 9 pages. LateX. Minor corrections | Phys.Lett. B545 (2002) 373-378 | 10.1016/S0370-2693(02)02622-9 | null | gr-qc | null | Vacuum gravitational fields invariant for a non Abelian Lie algebra generated
by two Killing fields whose commutator is light-like are analyzed. It is shown
that they represent nonlinear gravitational waves obeying to two nonlinear
superposition laws. The energy and the polarization of this family of waves are
explicitely evaluated.
| [
{
"created": "Sun, 12 May 2002 14:33:49 GMT",
"version": "v1"
},
{
"created": "Mon, 27 May 2002 10:44:07 GMT",
"version": "v2"
}
] | 2009-11-07 | [
[
"Canfora",
"F.",
""
],
[
"Vilasi",
"G.",
""
],
[
"Vitale",
"P.",
""
]
] | Vacuum gravitational fields invariant for a non Abelian Lie algebra generated by two Killing fields whose commutator is light-like are analyzed. It is shown that they represent nonlinear gravitational waves obeying to two nonlinear superposition laws. The energy and the polarization of this family of waves are explicitely evaluated. |
gr-qc/0411128 | Joachim Moortgat | Joachim Moortgat, Jan Kuijpers | Gravitational wave interactions with magnetized plasmas | 4 pages. Proceedings of the NATO Advanced Study Institute on the
Electromagnetic Spectrum of Neutron Stars, Marmaris, Turkey, June 2004 | null | null | null | gr-qc astro-ph | null | Gravitational waves (GWs) propagating through a uniformly magnetized plasma
interact directly with the magnetic field and excite magnetohydrodynamic (MHD)
waves with both electromagnetic and matter components. We study this process
for arbitrary geometry in the MHD approximation and find that all three
fundamental MHD modes -- slow and fast magnetosonic, and Alfven -- are excited
depending on both the polarization of the GW and the orientation of the ambient
magnetic field. The latter two modes can interact coherently with the GW
resulting in damping of the GW and linear growth of the plasma waves.
| [
{
"created": "Fri, 26 Nov 2004 22:39:52 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Moortgat",
"Joachim",
""
],
[
"Kuijpers",
"Jan",
""
]
] | Gravitational waves (GWs) propagating through a uniformly magnetized plasma interact directly with the magnetic field and excite magnetohydrodynamic (MHD) waves with both electromagnetic and matter components. We study this process for arbitrary geometry in the MHD approximation and find that all three fundamental MHD modes -- slow and fast magnetosonic, and Alfven -- are excited depending on both the polarization of the GW and the orientation of the ambient magnetic field. The latter two modes can interact coherently with the GW resulting in damping of the GW and linear growth of the plasma waves. |
1211.2110 | Anthony Walters | Anthony Walters and Charles Hellaby | Constructing Realistic Szekeres Models from Initial and Final Data | 40 pages; 18 figures; To be published in JCAP | null | 10.1088/1475-7516/2012/12/001 | uct-cosmology-2012-11-09-14:10 | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Szekeres family of inhomogeneous solutions, which are defined by six
arbitrary metric functions, offers a wide range of possibilities for modelling
cosmic structure. Here we present a model construction procedure for the
quasispherical case using given data at initial and final times. Of the six
arbitrary metric functions, the three which are common to both Szekeres and
Lema\^itre-Tolman models are determined by the model construction procedure of
Krasinski & Hellaby. For the remaining three functions, which are unique to
Szekeres models, we derive exact analytic expressions in terms of more
physically intuitive quantities - density profiles and dipole orientation
angles. Using MATLAB, we implement the model construction procedure and
simulate the time evolution.
| [
{
"created": "Fri, 9 Nov 2012 12:13:37 GMT",
"version": "v1"
}
] | 2015-06-12 | [
[
"Walters",
"Anthony",
""
],
[
"Hellaby",
"Charles",
""
]
] | The Szekeres family of inhomogeneous solutions, which are defined by six arbitrary metric functions, offers a wide range of possibilities for modelling cosmic structure. Here we present a model construction procedure for the quasispherical case using given data at initial and final times. Of the six arbitrary metric functions, the three which are common to both Szekeres and Lema\^itre-Tolman models are determined by the model construction procedure of Krasinski & Hellaby. For the remaining three functions, which are unique to Szekeres models, we derive exact analytic expressions in terms of more physically intuitive quantities - density profiles and dipole orientation angles. Using MATLAB, we implement the model construction procedure and simulate the time evolution. |
gr-qc/9807068 | Jonathan Wilson | J. A. Vickers, J. P. Wilson | A nonlinear theory of tensor distributions | 16 pages, AMS-TeX | null | null | null | gr-qc | null | The coordinate invariant theory of generalised functions of Colombeau and
Meril is reviewed and extended to enable the construction of multi-index
generalised tensor functions whose transformation laws coincide with their
counterparts in classical distribution theory.
| [
{
"created": "Fri, 24 Jul 1998 09:42:31 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Vickers",
"J. A.",
""
],
[
"Wilson",
"J. P.",
""
]
] | The coordinate invariant theory of generalised functions of Colombeau and Meril is reviewed and extended to enable the construction of multi-index generalised tensor functions whose transformation laws coincide with their counterparts in classical distribution theory. |
gr-qc/9406001 | Haret Rosu | Haret Rosu and Marco Reyes | Shannon-Wehrl entropy for cosmological and black hole squeezing | 4 pages, 2 Figures available from the author(s), LaTex, IFUG-11/94 r,
contribution to Harmonic Oscillators 2, Cocoyoc, March 23-25/1994, To be
published in NASA Conference Series (1994/1995) | Int.J.Mod.Phys. D4 (1995) 327-332 | 10.1142/S0218271895000247 | null | gr-qc | null | We discuss the Shannon-Wehrl entropy within the squeezing vocabulary for the
cosmological and black hole particle production.
| [
{
"created": "Wed, 1 Jun 1994 23:14:00 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Rosu",
"Haret",
""
],
[
"Reyes",
"Marco",
""
]
] | We discuss the Shannon-Wehrl entropy within the squeezing vocabulary for the cosmological and black hole particle production. |
2402.07649 | Samad Khakshournia | S. Khakshournia and R. Mansouri | Revisiting effective Einstein equations on a 3-brane in the presence of
torsion | 12 pages | Gravitation and Cosmology, 2023, Vol. 29, No. 3, pp. 220-226 | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The effective Einstein equations on a 3-brane embedded in a 5-dimensional
Riemann-Cartan bulk spacetime are revisited. Addressing the shortcomings in the
hitherto published junction conditions on the brane in the presence of torsion,
we have elaborated on our general form of the junction conditions recently
published. Applying our general junction conditions, we have formulated the
effective Einstein equations on a Z2 symmetric brane in a standard form
highlighting the difference to those published so far.
| [
{
"created": "Mon, 12 Feb 2024 13:46:12 GMT",
"version": "v1"
}
] | 2024-02-13 | [
[
"Khakshournia",
"S.",
""
],
[
"Mansouri",
"R.",
""
]
] | The effective Einstein equations on a 3-brane embedded in a 5-dimensional Riemann-Cartan bulk spacetime are revisited. Addressing the shortcomings in the hitherto published junction conditions on the brane in the presence of torsion, we have elaborated on our general form of the junction conditions recently published. Applying our general junction conditions, we have formulated the effective Einstein equations on a Z2 symmetric brane in a standard form highlighting the difference to those published so far. |
gr-qc/0601051 | Valerii Dryuma sem | Valerii Dryuma | Four-dimensional Einstein spaces on Six-dimensional Ricci-flat base
space | 9 pages | null | null | null | gr-qc nlin.SI | null | The examples of ten-dimensional vacuum Einstein spaces composed of
four-dimensional Einstein spaces and six-dimensional Ricci-flat base space
defined by the solutions of the Korteveg de-Vries equation are constructed.
| [
{
"created": "Thu, 12 Jan 2006 17:38:23 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Dryuma",
"Valerii",
""
]
] | The examples of ten-dimensional vacuum Einstein spaces composed of four-dimensional Einstein spaces and six-dimensional Ricci-flat base space defined by the solutions of the Korteveg de-Vries equation are constructed. |
2112.07600 | Celia Escamilla-Rivera | Carlos Ar\'aoz Alvarado and Celia Escamilla-Rivera | Modified Yang-Lee theory for nonlocal gravitational potential and their
phase transition | Version accepted in International Journal of Geometric Methods in
Modern Physics | International Journal of Geometric Methods in Modern Physics
(2022) 2250053 | 10.1142/S0219887822500530 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | In this paper, we describe the extension to study the thermodynamics of the
structure formation in the large scale Universe in the nonlocal gravity
formalism using standard statistical mechanics. From the derivation of the
grand partition function in a modified version of the Yang-Lee theory, we
obtained the corresponding thermodynamics properties that can be in consistency
with a Bose-Einstein dark matter framework and derive its gravitational phase
transition.
| [
{
"created": "Tue, 14 Dec 2021 17:51:50 GMT",
"version": "v1"
}
] | 2022-01-14 | [
[
"Alvarado",
"Carlos Aráoz",
""
],
[
"Escamilla-Rivera",
"Celia",
""
]
] | In this paper, we describe the extension to study the thermodynamics of the structure formation in the large scale Universe in the nonlocal gravity formalism using standard statistical mechanics. From the derivation of the grand partition function in a modified version of the Yang-Lee theory, we obtained the corresponding thermodynamics properties that can be in consistency with a Bose-Einstein dark matter framework and derive its gravitational phase transition. |
1904.08124 | Tekin Dereli | Tekin Dereli, Cem Yeti\c{s}mi\c{s}o\u{g}lu | Weyl Covariant Theories of Gravity in Riemann-Cartan-Weyl Space-times I.
Topologically Massive Gravity | null | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss locally Weyl (scale) covariant generalisations of gravitational
theories using Riemann-Cartan-Weyl space-times in arbitrary dimensions. We
demonstrate the procedure of Weyl gauging on two examples in particular:
General relativity, and topologically massive gravity in three dimensions.
| [
{
"created": "Wed, 17 Apr 2019 08:20:36 GMT",
"version": "v1"
}
] | 2019-04-18 | [
[
"Dereli",
"Tekin",
""
],
[
"Yetişmişoğlu",
"Cem",
""
]
] | We discuss locally Weyl (scale) covariant generalisations of gravitational theories using Riemann-Cartan-Weyl space-times in arbitrary dimensions. We demonstrate the procedure of Weyl gauging on two examples in particular: General relativity, and topologically massive gravity in three dimensions. |
1908.08247 | Katarina Martinovic | Katarina Martinovic, Mairi Sakellariadou | Constraints on Quasi-dilaton Massive Gravity | 8 pages | Phys. Rev. D 100, 124016 (2019) | 10.1103/PhysRevD.100.124016 | null | gr-qc astro-ph.GA | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The last decade has seen great advancements in the field of modified gravity,
motivated by the dark energy problem, or by the search for a fundamental
quantum gravity theory. With a phenomenologically-driven approach, we consider
dRGT theory and its extension, quasi-dilaton massive gravity (QDMG). When
looking for ways to constrain the theory, a promising direction appeared to be
astrophysical tests. The scalar gravitational degree of freedom and
quasi-dilaton degree of freedom alter the evolution of Bardeen potentials,
which in turn affects the galaxy rotation curves. We find an upper bound on
graviton mass in QDMG to be $m \leq 10^{-31} {\rm eV}$. This result agrees with
bounds from LIGO and numerous Solar System tests. However, the extremely small
mass of the graviton remains a detection out of reach, with LISA's sensitivity
exploring the parameter space up to $m \leq 10^{-25} {\rm eV}$.
| [
{
"created": "Thu, 22 Aug 2019 08:15:27 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Jan 2020 16:14:44 GMT",
"version": "v2"
}
] | 2020-01-17 | [
[
"Martinovic",
"Katarina",
""
],
[
"Sakellariadou",
"Mairi",
""
]
] | The last decade has seen great advancements in the field of modified gravity, motivated by the dark energy problem, or by the search for a fundamental quantum gravity theory. With a phenomenologically-driven approach, we consider dRGT theory and its extension, quasi-dilaton massive gravity (QDMG). When looking for ways to constrain the theory, a promising direction appeared to be astrophysical tests. The scalar gravitational degree of freedom and quasi-dilaton degree of freedom alter the evolution of Bardeen potentials, which in turn affects the galaxy rotation curves. We find an upper bound on graviton mass in QDMG to be $m \leq 10^{-31} {\rm eV}$. This result agrees with bounds from LIGO and numerous Solar System tests. However, the extremely small mass of the graviton remains a detection out of reach, with LISA's sensitivity exploring the parameter space up to $m \leq 10^{-25} {\rm eV}$. |
1611.00667 | Andronikos Paliathanasis | G. Papagiannopoulos, John D. Barrow, S. Basilakos, A. Giacomini and A.
Paliathanasis | Dynamical symmetries in Brans-Dicke cosmology | 15 pages; 2 figures; accepted for publication by Phys. Rev. D | Phys. Rev. D 95, 024021 (2017) | 10.1103/PhysRevD.95.024021 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the context of generalised Brans-Dicke cosmology we use the Killing
tensors of the minisuperspace in order to determine the unspecified potential
of a scalar-tensor gravity theory. Specifically, based on the existence of
contact symmetries of the field equations, we find four types of potentials
which provide exactly integrable dynamical systems. We investigate the
dynamical properties of these potentials by using a critical point analysis and
we find solutions which lead to cosmic acceleration and under specific
conditions we can have de-Sitter points as stable late-time attractors.
| [
{
"created": "Wed, 2 Nov 2016 16:21:55 GMT",
"version": "v1"
},
{
"created": "Tue, 20 Dec 2016 18:20:53 GMT",
"version": "v2"
}
] | 2017-01-24 | [
[
"Papagiannopoulos",
"G.",
""
],
[
"Barrow",
"John D.",
""
],
[
"Basilakos",
"S.",
""
],
[
"Giacomini",
"A.",
""
],
[
"Paliathanasis",
"A.",
""
]
] | In the context of generalised Brans-Dicke cosmology we use the Killing tensors of the minisuperspace in order to determine the unspecified potential of a scalar-tensor gravity theory. Specifically, based on the existence of contact symmetries of the field equations, we find four types of potentials which provide exactly integrable dynamical systems. We investigate the dynamical properties of these potentials by using a critical point analysis and we find solutions which lead to cosmic acceleration and under specific conditions we can have de-Sitter points as stable late-time attractors. |
1603.02233 | Hor\'acio Santana Vieira | H. S. Vieira, V. B. Bezerra | Confluent Heun functions and the physics of black holes: resonant
frequencies, Hawking radiation and scattering of scalar waves | 18 pages. This paper was unified and published with arXiv:1603.02240 | Annals of Physics 373 (2016) 28-42 | 10.1016/j.aop.2016.06.016 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We apply the confluent Heun functions to study the resonant frequencies
(quasispectrum), the Hawking radiation and the scattering process of scalar
waves, in a class of spacetimes, namely, the ones generated by a
Kerr-Newman-Kasuya spacetime (dyon black hole) and a Reissner-Nordstr\"{o}m
black hole surrounded by a magnetic field (Ernst spacetime). In both
spacetimes, the solutions for the angular and radial parts of the corresponding
Klein-Gordon equations are obtained exactly, for massive and massless fields,
respectively. The special cases of Kerr and Schwarzschild black holes are
analyzed and the solutions obtained, as well as in the case of a Schwarzschild
black hole surrounded by a magnetic field. In all these special situations, the
resonant frequencies, Hawking radiation and scattering are studied.
| [
{
"created": "Mon, 7 Mar 2016 20:03:35 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Jul 2016 01:31:41 GMT",
"version": "v2"
}
] | 2016-07-28 | [
[
"Vieira",
"H. S.",
""
],
[
"Bezerra",
"V. B.",
""
]
] | We apply the confluent Heun functions to study the resonant frequencies (quasispectrum), the Hawking radiation and the scattering process of scalar waves, in a class of spacetimes, namely, the ones generated by a Kerr-Newman-Kasuya spacetime (dyon black hole) and a Reissner-Nordstr\"{o}m black hole surrounded by a magnetic field (Ernst spacetime). In both spacetimes, the solutions for the angular and radial parts of the corresponding Klein-Gordon equations are obtained exactly, for massive and massless fields, respectively. The special cases of Kerr and Schwarzschild black holes are analyzed and the solutions obtained, as well as in the case of a Schwarzschild black hole surrounded by a magnetic field. In all these special situations, the resonant frequencies, Hawking radiation and scattering are studied. |
0706.3757 | Yun Soo Myung | Yun Soo Myung | Instability of holographic dark energy models | 11 pages, 4 eps figures, to appear in PLB | Phys.Lett.B652:223-227,2007 | 10.1016/j.physletb.2007.07.033 | INJE-TP-07-05 | gr-qc astro-ph hep-th | null | We investigate the difference between holographic dark energy, Chaplygin gas,
and tachyon model with constant potential. For this purpose, we examine their
squared speeds of sound which are evaluated to zeroth order in perturbation
theory and hence depends only on time. We find that the squared speed for
holographic dark energy is always negative when choosing the future event
horizon as the IR cutoff, while those for Chaplygin gas and tachyon are
non-negative. This means that the perfect fluid for holographic dark energy is
classically unstable. Hence the holographic interpretation for Chaplygin gas
and tachyon is problematic.
| [
{
"created": "Tue, 26 Jun 2007 05:09:59 GMT",
"version": "v1"
},
{
"created": "Fri, 20 Jul 2007 04:49:54 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Myung",
"Yun Soo",
""
]
] | We investigate the difference between holographic dark energy, Chaplygin gas, and tachyon model with constant potential. For this purpose, we examine their squared speeds of sound which are evaluated to zeroth order in perturbation theory and hence depends only on time. We find that the squared speed for holographic dark energy is always negative when choosing the future event horizon as the IR cutoff, while those for Chaplygin gas and tachyon are non-negative. This means that the perfect fluid for holographic dark energy is classically unstable. Hence the holographic interpretation for Chaplygin gas and tachyon is problematic. |
1811.01093 | Tyson Littenberg | Tyson B. Littenberg and Nicolas Yunes | Binary White Dwarfs as Laboratories for Extreme Gravity with LISA | 18 pages, 10 figures, submitted to CQG | null | 10.1088/1361-6382/ab0a3d | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The observation of low-frequency gravitational waves with the Laser
Interferometer Space Antenna will allow the study of new sources of
gravitational radiation that are not accessible by ground-based instruments.
Gravitational wave sources provide invaluable information both about their
astrophysics, as well as the nature of the gravitational interaction in their
neighborhoods. One low frequency source that has not received much attention
regarding the latter are galactic binaries composed of two white dwarves or a
white dwarf and a neutron star. We here show that, contrary to the common lore,
such gravitational wave sources can indeed be used to constrain an important
feature of the gravitational interaction: the absence of pre-Newtonian, dipolar
dissipation. We propose a model-independent framework to carry out a null test
for the presence of this feature in the data that is very much analogous to
tests of General Relativity with radio-observations of binary pulsars. We then
go one step further and specialize this test to scalar-tensor theories to
derive projected constraints on spontaneous scalarization. We find that these
constraints can be comparable to current bounds with binary pulsars, and in
some optimistic cases, they can be even stronger.
| [
{
"created": "Fri, 2 Nov 2018 21:17:34 GMT",
"version": "v1"
}
] | 2019-05-22 | [
[
"Littenberg",
"Tyson B.",
""
],
[
"Yunes",
"Nicolas",
""
]
] | The observation of low-frequency gravitational waves with the Laser Interferometer Space Antenna will allow the study of new sources of gravitational radiation that are not accessible by ground-based instruments. Gravitational wave sources provide invaluable information both about their astrophysics, as well as the nature of the gravitational interaction in their neighborhoods. One low frequency source that has not received much attention regarding the latter are galactic binaries composed of two white dwarves or a white dwarf and a neutron star. We here show that, contrary to the common lore, such gravitational wave sources can indeed be used to constrain an important feature of the gravitational interaction: the absence of pre-Newtonian, dipolar dissipation. We propose a model-independent framework to carry out a null test for the presence of this feature in the data that is very much analogous to tests of General Relativity with radio-observations of binary pulsars. We then go one step further and specialize this test to scalar-tensor theories to derive projected constraints on spontaneous scalarization. We find that these constraints can be comparable to current bounds with binary pulsars, and in some optimistic cases, they can be even stronger. |
gr-qc/0701110 | Keisuke Taniguchi | Keisuke Taniguchi, Thomas W. Baumgarte, Joshua A. Faber, and Stuart L.
Shapiro | Quasiequilibrium black hole-neutron star binaries in general relativity | 17 pages, 15 figures, published in Phys. Rev. D | Phys.Rev.D75:084005,2007 | 10.1103/PhysRevD.75.084005 | null | gr-qc astro-ph | null | We construct quasiequilibrium sequences of black hole-neutron star binaries
in general relativity. We solve Einstein's constraint equations in the
conformal thin-sandwich formalism, subject to black hole boundary conditions
imposed on the surface of an excised sphere, together with the relativistic
equations of hydrostatic equilibrium. In contrast to our previous calculations
we adopt a flat spatial background geometry and do not assume extreme mass
ratios. We adopt a Gamma=2 polytropic equation of state and focus on
irrotational neutron star configurations as well as approximately nonspinning
black holes. We present numerical results for ratios of the black hole's
irreducible mass to the neutron star's ADM mass in isolation of
M_{irr}^{BH}/M_{ADM,0}^{NS} = 1, 2, 3, 5, and 10. We consider neutron stars of
baryon rest mass M_B^{NS}/M_B^{max} = 83% and 56%, where M_B^{max} is the
maximum allowed rest mass of a spherical star in isolation for our equation of
state. For these sequences, we locate the onset of tidal disruption and, in
cases with sufficiently large mass ratios and neutron star compactions, the
innermost stable circular orbit. We compare with previous results for black
hole-neutron star binaries and find excellent agreement with third-order
post-Newtonian results, especially for large binary separations. We also use
our results to estimate the energy spectrum of the outgoing gravitational
radiation emitted during the inspiral phase for these binaries.
| [
{
"created": "Fri, 19 Jan 2007 21:00:06 GMT",
"version": "v1"
},
{
"created": "Wed, 24 Oct 2007 19:58:58 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Taniguchi",
"Keisuke",
""
],
[
"Baumgarte",
"Thomas W.",
""
],
[
"Faber",
"Joshua A.",
""
],
[
"Shapiro",
"Stuart L.",
""
]
] | We construct quasiequilibrium sequences of black hole-neutron star binaries in general relativity. We solve Einstein's constraint equations in the conformal thin-sandwich formalism, subject to black hole boundary conditions imposed on the surface of an excised sphere, together with the relativistic equations of hydrostatic equilibrium. In contrast to our previous calculations we adopt a flat spatial background geometry and do not assume extreme mass ratios. We adopt a Gamma=2 polytropic equation of state and focus on irrotational neutron star configurations as well as approximately nonspinning black holes. We present numerical results for ratios of the black hole's irreducible mass to the neutron star's ADM mass in isolation of M_{irr}^{BH}/M_{ADM,0}^{NS} = 1, 2, 3, 5, and 10. We consider neutron stars of baryon rest mass M_B^{NS}/M_B^{max} = 83% and 56%, where M_B^{max} is the maximum allowed rest mass of a spherical star in isolation for our equation of state. For these sequences, we locate the onset of tidal disruption and, in cases with sufficiently large mass ratios and neutron star compactions, the innermost stable circular orbit. We compare with previous results for black hole-neutron star binaries and find excellent agreement with third-order post-Newtonian results, especially for large binary separations. We also use our results to estimate the energy spectrum of the outgoing gravitational radiation emitted during the inspiral phase for these binaries. |
1407.0032 | Marina Cort\^es | Marina Cort\^es and Lee Smolin | Spin foam models as energetic causal sets | 16 pages, 4 figures. v2 typo corrected, references added | Phys. Rev. D 93, 084039 (2016) | 10.1103/PhysRevD.93.084039 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Energetic causal sets are causal sets endowed by a flow of energy-momentum
between causally related events. These incorporate a novel mechanism for the
emergence of space-time from causal relations. Here we construct a spin foam
model which is also an energetic causal set model. This model is closely
related to the model introduced in parallel by Wolfgang Wieland in
arXiv:1407.0025, and this construction makes use of results used there. What
makes a spin foam model also an energetic causal set is Wieland's
identification of new momenta, conserved at events (or four-simplices), whose
norms are not mass, but the volume of tetrahedra. This realizes the torsion
constraints, which are missing in previous spin foam models, and are needed to
relate the connection dynamics to those of the metric, as in general
relativity. This identification makes it possible to apply the new mechanism
for the emergence of space-time to a spin foam model.
| [
{
"created": "Mon, 30 Jun 2014 20:01:01 GMT",
"version": "v1"
},
{
"created": "Mon, 28 Jul 2014 20:03:36 GMT",
"version": "v2"
}
] | 2016-04-27 | [
[
"Cortês",
"Marina",
""
],
[
"Smolin",
"Lee",
""
]
] | Energetic causal sets are causal sets endowed by a flow of energy-momentum between causally related events. These incorporate a novel mechanism for the emergence of space-time from causal relations. Here we construct a spin foam model which is also an energetic causal set model. This model is closely related to the model introduced in parallel by Wolfgang Wieland in arXiv:1407.0025, and this construction makes use of results used there. What makes a spin foam model also an energetic causal set is Wieland's identification of new momenta, conserved at events (or four-simplices), whose norms are not mass, but the volume of tetrahedra. This realizes the torsion constraints, which are missing in previous spin foam models, and are needed to relate the connection dynamics to those of the metric, as in general relativity. This identification makes it possible to apply the new mechanism for the emergence of space-time to a spin foam model. |
gr-qc/9302017 | Don N. Page | Valery P. Frolov and Don N. Page | Proof of the Generalized Second Law for Quasistationary Semiclassical
Black Holes | 12 pages, LaTeX, report Alberta-Thy-10-93 (revision of paper in
response to Phys. Rev. Lett. referees' comments, which suffered a series of
long delays) | Phys.Rev.Lett.71:3902-3905,1993 | 10.1103/PhysRevLett.71.3902 | null | gr-qc | null | A simple direct explicit proof of the generalized second law of black hole
thermodynamics is given for a quasistationary semiclassical black hole.
| [
{
"created": "Mon, 15 Feb 1993 22:25:17 GMT",
"version": "v1"
},
{
"created": "Tue, 16 Feb 1993 17:58:54 GMT",
"version": "v2"
},
{
"created": "Wed, 17 Feb 1993 19:03:57 GMT",
"version": "v3"
},
{
"created": "Tue, 17 Aug 1993 23:17:35 GMT",
"version": "v4"
}
] | 2010-11-01 | [
[
"Frolov",
"Valery P.",
""
],
[
"Page",
"Don N.",
""
]
] | A simple direct explicit proof of the generalized second law of black hole thermodynamics is given for a quasistationary semiclassical black hole. |
1811.05435 | Nicol\'as Lorenzo Gonz\'alez Albornoz | N.L. Gonz\'alez Albornoz, Dieter Lust, S. Salgado, Angnis Schmidt-May | 4D spin-2 fields from 5D Chern-Simons theory | 31 pages, no figures, added references | J. High Energ. Phys. (2018) 2018: 26 | 10.1007/JHEP12(2018)026 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a 5-dimensional Chern-Simons gauge theory for the isometry group
of Anti-de-Sitter spacetime,
$\operatorname{AdS}_{4+1}\simeq\operatorname{SO}(4,2)$, and invoke different
dimensional reduction schemes in order to relate it to 4-dimensional spin-2
theories. The AdS gauge algebra is isomorphic to a parametrized 4-dimensional
conformal algebra, and the gauge fields corresponding to the generators of
non-Abelian translations and special conformal transformations reduce to two
vierbein fields in $D=4$. Besides these two vierbeine, our reduction schemes
leave only the Lorentz spin connection as an additional dynamical field in the
4-dimensional theories. We identify the corresponding actions as particular
generalizations of Einstein-Cartan theory, conformal gravity and ghost-free
bimetric gravity in first-order form.
| [
{
"created": "Tue, 13 Nov 2018 17:54:16 GMT",
"version": "v1"
},
{
"created": "Sun, 16 Dec 2018 13:32:27 GMT",
"version": "v2"
}
] | 2018-12-18 | [
[
"Albornoz",
"N. L. González",
""
],
[
"Lust",
"Dieter",
""
],
[
"Salgado",
"S.",
""
],
[
"Schmidt-May",
"Angnis",
""
]
] | We consider a 5-dimensional Chern-Simons gauge theory for the isometry group of Anti-de-Sitter spacetime, $\operatorname{AdS}_{4+1}\simeq\operatorname{SO}(4,2)$, and invoke different dimensional reduction schemes in order to relate it to 4-dimensional spin-2 theories. The AdS gauge algebra is isomorphic to a parametrized 4-dimensional conformal algebra, and the gauge fields corresponding to the generators of non-Abelian translations and special conformal transformations reduce to two vierbein fields in $D=4$. Besides these two vierbeine, our reduction schemes leave only the Lorentz spin connection as an additional dynamical field in the 4-dimensional theories. We identify the corresponding actions as particular generalizations of Einstein-Cartan theory, conformal gravity and ghost-free bimetric gravity in first-order form. |
1601.04343 | Yorgo Senikoglu | Metin Arik and Yorgo Senikoglu | Cosmological isotropic matter-energy generalizations of Schwarzschild
and Kerr metrics | 12 pages, accepted version for publication in Int.J.Mod.Phys.D | Int. J. Mod. Phys. D 25, No 10 (2016) 1650088 | 10.1142/S0218271816500887 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a time dependent isotropic fluid solution around a Schwarzschild
black hole. We offer the solutions and discuss the effects on the field
equations and the horizon. We derive the energy density, pressure and the
equation of state parameter. In the second part, we generalize the rotating
black hole solution to an expanding universe. We derive from the proposed
metric the special solutions of the field equations for the dust approximation
and the dark energy solution. We show that the presence of a rotating black
hole does not modify the scale factor $b(t)=t^{2/3}$ law for dust, nor
$b(t)=e^{\lambda\hspace{1mm}t}$ and $p=-\rho$ for dark energy.
| [
{
"created": "Sun, 17 Jan 2016 20:45:20 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Apr 2016 14:42:59 GMT",
"version": "v2"
}
] | 2018-07-26 | [
[
"Arik",
"Metin",
""
],
[
"Senikoglu",
"Yorgo",
""
]
] | We present a time dependent isotropic fluid solution around a Schwarzschild black hole. We offer the solutions and discuss the effects on the field equations and the horizon. We derive the energy density, pressure and the equation of state parameter. In the second part, we generalize the rotating black hole solution to an expanding universe. We derive from the proposed metric the special solutions of the field equations for the dust approximation and the dark energy solution. We show that the presence of a rotating black hole does not modify the scale factor $b(t)=t^{2/3}$ law for dust, nor $b(t)=e^{\lambda\hspace{1mm}t}$ and $p=-\rho$ for dark energy. |
2103.04676 | Zhan-Feng Mai | Jia-Hui Huang, Mu-Zi Zhang, Tian-Tian Cao, Yi-Feng Zou and Zhan-Feng
Mai | Superradiantly stability analysis on dyonic stringly black hole | 9 pages, 3 figures. arXiv admin note: text overlap with
arXiv:1809.07345 | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The black hole superradiance phenomena state that when a scalar wave
perturbation is properly scattering off a charged or rotating black hole, the
energy of the reflected scalar wave may be amplified. If this amplification
process can occur back and forth through certain confining mechanisms, it will
lead to strong instability of the black hole, which is so-called "black hole
bomb". In this paper, the superradiant stability is investigated for dyonic
black holes in string theory. Although the electric charged black hole in
string theory has been proved superrdiantly stable, it is found that the dyonic
black hole is more unstable than an RN black hole due to the magnetic charge.
Furthermore, by our analysis of the effective potential outside the event
horizon, we give the region of the parameter associated with the superradiance
stability on dyonic stringly black hole.
| [
{
"created": "Mon, 8 Mar 2021 11:34:49 GMT",
"version": "v1"
}
] | 2021-03-09 | [
[
"Huang",
"Jia-Hui",
""
],
[
"Zhang",
"Mu-Zi",
""
],
[
"Cao",
"Tian-Tian",
""
],
[
"Zou",
"Yi-Feng",
""
],
[
"Mai",
"Zhan-Feng",
""
]
] | The black hole superradiance phenomena state that when a scalar wave perturbation is properly scattering off a charged or rotating black hole, the energy of the reflected scalar wave may be amplified. If this amplification process can occur back and forth through certain confining mechanisms, it will lead to strong instability of the black hole, which is so-called "black hole bomb". In this paper, the superradiant stability is investigated for dyonic black holes in string theory. Although the electric charged black hole in string theory has been proved superrdiantly stable, it is found that the dyonic black hole is more unstable than an RN black hole due to the magnetic charge. Furthermore, by our analysis of the effective potential outside the event horizon, we give the region of the parameter associated with the superradiance stability on dyonic stringly black hole. |
1405.0265 | Panagiota Kanti | Athanasios Bakopoulos and Panagiota Kanti | From GEM to Electromagnetism | 18 pages, Latex2e file, typos corrected, comments and references
added, accepted for publication in General Relativity and Gravitation | null | 10.1007/s10714-014-1742-y | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the first part of the present work, we focus on the theory of
gravitoelectromagnetism (GEM), and we derive the full set of equations and
constraints that the GEM scalar and vector potentials ought to satisfy. We
discuss important aspects of the theory, such as the presence of additional
constraints resulting from the field equations and gauge condition, the
requirement of the time-independence of the vector potential and the emergence
of additional terms in the expression of the Lorentz force. We also propose an
alternative ansatz for the metric perturbations that is found to be compatible
only with a vacuum configuration but evades several of the aforementioned
obstacles. In the second part of this work, we pose the question of whether a
tensorial theory using the formalism of General Relativity could re-produce the
theory of Electromagnetism. We demonstrate that the full set of Maxwell's
equations can be exactly re-produced for a large class of models, but the
framework has several weak points common with those found in GEM.
| [
{
"created": "Thu, 1 May 2014 19:35:27 GMT",
"version": "v1"
},
{
"created": "Sun, 18 May 2014 16:21:10 GMT",
"version": "v2"
}
] | 2015-06-19 | [
[
"Bakopoulos",
"Athanasios",
""
],
[
"Kanti",
"Panagiota",
""
]
] | In the first part of the present work, we focus on the theory of gravitoelectromagnetism (GEM), and we derive the full set of equations and constraints that the GEM scalar and vector potentials ought to satisfy. We discuss important aspects of the theory, such as the presence of additional constraints resulting from the field equations and gauge condition, the requirement of the time-independence of the vector potential and the emergence of additional terms in the expression of the Lorentz force. We also propose an alternative ansatz for the metric perturbations that is found to be compatible only with a vacuum configuration but evades several of the aforementioned obstacles. In the second part of this work, we pose the question of whether a tensorial theory using the formalism of General Relativity could re-produce the theory of Electromagnetism. We demonstrate that the full set of Maxwell's equations can be exactly re-produced for a large class of models, but the framework has several weak points common with those found in GEM. |
gr-qc/0406050 | Vladimir Khatsymovsky | V.M. Khatsymovsky | Modification of quantum measure in area tensor Regge calculus and
positivity | 10 pages, plain LaTeX | Phys.Lett. B601 (2004) 229-235 | 10.1016/j.physletb.2004.09.039 | null | gr-qc | null | A comparative analysis of the versions of quantum measure in the area tensor
Regge calculus is performed on the simplest configurations of the system. The
quantum measure is constructed in such the way that it reduces to the Feynman
path integral describing canonical quantisation if the continuous limit along
any of the coordinates is taken. As we have found earlier, it is possible to
implement also the correspondence principle (proportionality of the Lorentzian
(Euclidean) measure to $e^{iS}$ ($e^{-S}$), $S$ being the action). For that a
certain kind of the connection representation of the Regge action should be
used, namely, as a sum of independent contributions of selfdual and
antiselfdual sectors (that is, effectively 3-dimensional ones). There are two
such representations, the (anti)selfdual connections being SU(2) or SO(3)
rotation matrices according to the two ways of decomposing full SO(4) group, as
SU(2) $\times$ SU(2) or SO(3) $\times$ SO(3). The measure from SU(2) rotations
although positive on physical surface violates positivity outside this surface
in the general configuration space of arbitrary independent area tensors. The
measure based on SO(3) rotations is expected to be positive in this general
configuration space on condition that the scale of area tensors considered as
parameters is bounded from above by the value of the order of Plank unit.
| [
{
"created": "Fri, 11 Jun 2004 15:39:27 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Khatsymovsky",
"V. M.",
""
]
] | A comparative analysis of the versions of quantum measure in the area tensor Regge calculus is performed on the simplest configurations of the system. The quantum measure is constructed in such the way that it reduces to the Feynman path integral describing canonical quantisation if the continuous limit along any of the coordinates is taken. As we have found earlier, it is possible to implement also the correspondence principle (proportionality of the Lorentzian (Euclidean) measure to $e^{iS}$ ($e^{-S}$), $S$ being the action). For that a certain kind of the connection representation of the Regge action should be used, namely, as a sum of independent contributions of selfdual and antiselfdual sectors (that is, effectively 3-dimensional ones). There are two such representations, the (anti)selfdual connections being SU(2) or SO(3) rotation matrices according to the two ways of decomposing full SO(4) group, as SU(2) $\times$ SU(2) or SO(3) $\times$ SO(3). The measure from SU(2) rotations although positive on physical surface violates positivity outside this surface in the general configuration space of arbitrary independent area tensors. The measure based on SO(3) rotations is expected to be positive in this general configuration space on condition that the scale of area tensors considered as parameters is bounded from above by the value of the order of Plank unit. |
0803.4309 | Takashi Tamaki | Takashi Tamaki | Post-Newtonian parameters in the tensor-vector-scalar theory | 8 pages, no figures, to be published in PRD | Phys.Rev.D77:124020,2008 | 10.1103/PhysRevD.77.124020 | null | gr-qc astro-ph hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate post-Newtonian parameters in the tensor-vector-scalar (TeVeS)
theory in a general setting while previous researches have been restricted to
spherically symmetric cases. Based on the assumption that both the physical and
Einstein metrics have Minkowski metric at the zeroth order, we show $\gamma =1$
as in the previous researches. We find two remarkable things for other
parameters. The first is the value $\beta =1$ while it has been reported that
$\beta\neq 1$ for the case when the vector field is not purely timelike. This
discrepancy occurs from the above assumption which is natural as a starting
point. The second is the result that the Newtonian potential must be static to
be consistent with the vector equation. As a result, we cannot determine
$\alpha_{1}$ and $\alpha_{2}$. We consider that it is related to the
instability against linear perturbation and occurrence of caustic singularities
for various initial perturbations which have been reported recently.
| [
{
"created": "Sun, 30 Mar 2008 09:16:24 GMT",
"version": "v1"
},
{
"created": "Sun, 18 May 2008 02:48:31 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Tamaki",
"Takashi",
""
]
] | We investigate post-Newtonian parameters in the tensor-vector-scalar (TeVeS) theory in a general setting while previous researches have been restricted to spherically symmetric cases. Based on the assumption that both the physical and Einstein metrics have Minkowski metric at the zeroth order, we show $\gamma =1$ as in the previous researches. We find two remarkable things for other parameters. The first is the value $\beta =1$ while it has been reported that $\beta\neq 1$ for the case when the vector field is not purely timelike. This discrepancy occurs from the above assumption which is natural as a starting point. The second is the result that the Newtonian potential must be static to be consistent with the vector equation. As a result, we cannot determine $\alpha_{1}$ and $\alpha_{2}$. We consider that it is related to the instability against linear perturbation and occurrence of caustic singularities for various initial perturbations which have been reported recently. |
gr-qc/0604016 | Aristide Baratin | Aristide Baratin, Laurent Freidel | Hidden Quantum Gravity in 3d Feynman diagrams | 35 pages, 4 figures, some comments added | Class.Quant.Grav.24:1993-2026,2007 | 10.1088/0264-9381/24/8/006 | null | gr-qc hep-th | null | In this work we show that 3d Feynman amplitudes of standard QFT in flat and
homogeneous space can be naturally expressed as expectation values of a
specific topological spin foam model. The main interest of the paper is to set
up a framework which gives a background independent perspective on usual field
theories and can also be applied in higher dimensions. We also show that this
Feynman graph spin foam model, which encodes the geometry of flat space-time,
can be purely expressed in terms of algebraic data associated with the Poincare
group. This spin foam model turns out to be the spin foam quantization of a BF
theory based on the Poincare group, and as such is related to a quantization of
3d gravity in the limit where the Newton constant G_N goes to 0. We investigate
the 4d case in a companion paper where the strategy proposed here leads to
similar results.
| [
{
"created": "Tue, 4 Apr 2006 20:48:34 GMT",
"version": "v1"
},
{
"created": "Wed, 28 Mar 2007 20:24:20 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Baratin",
"Aristide",
""
],
[
"Freidel",
"Laurent",
""
]
] | In this work we show that 3d Feynman amplitudes of standard QFT in flat and homogeneous space can be naturally expressed as expectation values of a specific topological spin foam model. The main interest of the paper is to set up a framework which gives a background independent perspective on usual field theories and can also be applied in higher dimensions. We also show that this Feynman graph spin foam model, which encodes the geometry of flat space-time, can be purely expressed in terms of algebraic data associated with the Poincare group. This spin foam model turns out to be the spin foam quantization of a BF theory based on the Poincare group, and as such is related to a quantization of 3d gravity in the limit where the Newton constant G_N goes to 0. We investigate the 4d case in a companion paper where the strategy proposed here leads to similar results. |
1807.08049 | Nicolas Yunes | Alexander Saffer and Nicolas Yunes | Angular Momentum Loss for a Binary System in Einstein-{\AE}ther Theory | 9 pages, 2 figures, submitted to PRD | Phys. Rev. D 98, 124015 (2018) | 10.1103/PhysRevD.98.124015 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The recent gravitational wave observations provide insight into the extreme
gravity regime of coalescing binaries, where gravity is strong, dynamical and
non-linear. The interpretation of these observations relies on the comparison
of the data to a gravitational wave model, which in turn depends on the orbital
evolution of the binary, and in particular on its orbital energy and angular
momentum decay. In this paper, we calculate the latter in the inspiral of a
non-spinning compact binary system within Einstein-\AE{}ther theory. From the
theory's gravitational wave stress energy tensor and a balance law, we compute
the angular momentum decay both as a function of the fields in the theory and
as a function of the multipole moments of the binary. We then specialize to a
Keplerian parameterization of the orbit to express the angular momentum decay
as a function of the binary's orbital elements. We conclude by combining this
with the orbital energy decay to find expressions for the decay of the
semi-major axis and the orbital eccentricity of the binary. We find that these
rates of decay are typically faster in Einstein-\AE{}ther theory than in
General Relativity due to the presence of dipole radiation. Such modifications
will imprint onto the chirp rate of gravitational waves, leaving a signature of
Einstein-\AE{}ther theory that if absent in the data could be used to
stringently constrain it.
| [
{
"created": "Fri, 20 Jul 2018 22:57:26 GMT",
"version": "v1"
}
] | 2018-12-19 | [
[
"Saffer",
"Alexander",
""
],
[
"Yunes",
"Nicolas",
""
]
] | The recent gravitational wave observations provide insight into the extreme gravity regime of coalescing binaries, where gravity is strong, dynamical and non-linear. The interpretation of these observations relies on the comparison of the data to a gravitational wave model, which in turn depends on the orbital evolution of the binary, and in particular on its orbital energy and angular momentum decay. In this paper, we calculate the latter in the inspiral of a non-spinning compact binary system within Einstein-\AE{}ther theory. From the theory's gravitational wave stress energy tensor and a balance law, we compute the angular momentum decay both as a function of the fields in the theory and as a function of the multipole moments of the binary. We then specialize to a Keplerian parameterization of the orbit to express the angular momentum decay as a function of the binary's orbital elements. We conclude by combining this with the orbital energy decay to find expressions for the decay of the semi-major axis and the orbital eccentricity of the binary. We find that these rates of decay are typically faster in Einstein-\AE{}ther theory than in General Relativity due to the presence of dipole radiation. Such modifications will imprint onto the chirp rate of gravitational waves, leaving a signature of Einstein-\AE{}ther theory that if absent in the data could be used to stringently constrain it. |
1408.0840 | Michael Coughlin | Michael Coughlin, Eric Thrane, Nelson Christensen | Detecting compact binary coalescences with seedless clustering | null | null | 10.1103/PhysRevD.90.083005 | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Compact binary coalescences are a promising source of gravitational waves for
second-generation interferometric gravitational-wave detectors. Although
matched filtering is the optimal search method for well-modeled systems,
alternative detection strategies can be used to guard against theoretical
errors (e.g., involving new physics and/or assumptions about spin/eccentricity)
while providing a measure of redundancy. In previous work, we showed how
"seedless clustering" can be used to detect long-lived gravitational-wave
transients in both targeted and all-sky searches. In this paper, we apply
seedless clustering to the problem of low-mass ($M_\text{total}\leq10M_\odot$)
compact binary coalescences for both spinning and eccentric systems. We show
that seedless clustering provides a robust and computationally efficient method
for detecting low-mass compact binaries.
| [
{
"created": "Tue, 5 Aug 2014 00:01:10 GMT",
"version": "v1"
}
] | 2015-06-22 | [
[
"Coughlin",
"Michael",
""
],
[
"Thrane",
"Eric",
""
],
[
"Christensen",
"Nelson",
""
]
] | Compact binary coalescences are a promising source of gravitational waves for second-generation interferometric gravitational-wave detectors. Although matched filtering is the optimal search method for well-modeled systems, alternative detection strategies can be used to guard against theoretical errors (e.g., involving new physics and/or assumptions about spin/eccentricity) while providing a measure of redundancy. In previous work, we showed how "seedless clustering" can be used to detect long-lived gravitational-wave transients in both targeted and all-sky searches. In this paper, we apply seedless clustering to the problem of low-mass ($M_\text{total}\leq10M_\odot$) compact binary coalescences for both spinning and eccentric systems. We show that seedless clustering provides a robust and computationally efficient method for detecting low-mass compact binaries. |
gr-qc/0302097 | Friedrich W. Hehl | Alberto A. Garcia, Friedrich W. Hehl, Christian Heinicke, Alfredo
Macias | Exact vacuum solution of a (1+2)-dimensional Poincare gauge theory: BTZ
solution with torsion | 16 pages latex, 1 figure, paper corrected and shortened | Phys.Rev. D67 (2003) 124016 | 10.1103/PhysRevD.67.124016 | null | gr-qc hep-th | null | In (1+2)-dimensional Poincar\'e gauge gravity, we start from a Lagrangian
depending on torsion and curvature which includes additionally {\em
translational} and {\em Lorentzian} Chern-Simons terms. Limiting ourselves to
to a specific subcase, the Mielke-Baekler (MB) model, we derive the
corresponding field equations (of Einstein-Cartan-Chern-Simons type) and find
the general vacuum solution. We determine the properties of this solution, in
particular its mass and its angular momentum. For vanishing torsion, we recover
the BTZ-solution. We also derive the general conformally flat vacuum solution
with torsion. In this framework, we discuss {\em Cartan's} (3-dimensional) {\em
spiral staircase} and find that it is not only a special case of our new vacuum
solution, but can alternatively be understood as a solution of the
3-dimensional Einstein-Cartan theory with matter of constant pressure and
constant torque.
| [
{
"created": "Mon, 24 Feb 2003 16:37:02 GMT",
"version": "v1"
},
{
"created": "Fri, 20 Jun 2003 22:52:43 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Garcia",
"Alberto A.",
""
],
[
"Hehl",
"Friedrich W.",
""
],
[
"Heinicke",
"Christian",
""
],
[
"Macias",
"Alfredo",
""
]
] | In (1+2)-dimensional Poincar\'e gauge gravity, we start from a Lagrangian depending on torsion and curvature which includes additionally {\em translational} and {\em Lorentzian} Chern-Simons terms. Limiting ourselves to to a specific subcase, the Mielke-Baekler (MB) model, we derive the corresponding field equations (of Einstein-Cartan-Chern-Simons type) and find the general vacuum solution. We determine the properties of this solution, in particular its mass and its angular momentum. For vanishing torsion, we recover the BTZ-solution. We also derive the general conformally flat vacuum solution with torsion. In this framework, we discuss {\em Cartan's} (3-dimensional) {\em spiral staircase} and find that it is not only a special case of our new vacuum solution, but can alternatively be understood as a solution of the 3-dimensional Einstein-Cartan theory with matter of constant pressure and constant torque. |
2110.01091 | Hongguang Liu | Muxin Han, Wojciech Kaminski, Hongguang Liu | Finiteness of spinfoam vertex amplitude with timelike polyhedra, and the
full amplitude | 29 pages | null | 10.1103/PhysRevD.105.084034 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This work focuses on Conrady-Hnybida's 4-dimensional extended spinfoam model
with timelike polyhedra, while we restrict all faces to be spacelike. Firstly,
we prove the absolute convergence of the vertex amplitude with timelike
polyhedra, when SU(1,1) boundary states are coherent states or the canonical
basis, or their finite linear combinations. Secondly, based on the finite
vertex amplitude and a proper prescription of the SU(1,1) intertwiner space, we
construct the extended spinfoam amplitude on arbitrary cellular complex, taking
into account the sum over SU(1,1) intertwiners of internal timelike polyhedra.
We observe that the sum over SU(1,1) intertwiners is infinite for the internal
timelike polyhedron that has at least 2 future-pointing and 2 past-pointing
face-normals. In order to regularize the possible divergence from summing over
SU(1,1) intertwiners, we develop a quantum cut-off scheme based on the
eigenvalue of the ``shadow operator''. The spinfoam amplitude with timelike
internal polyhedra (and spacelike faces) is finite, when 2 types of cut-offs
are imposed: one is imposed on $j$ the eigenvalue of area operator, the other
is imposed on the eigenvalue of shadow operator for every internal timelike
polyhedron that has at least 2 future-pointing and 2 past-pointing
face-normals.
| [
{
"created": "Sun, 3 Oct 2021 20:17:00 GMT",
"version": "v1"
}
] | 2022-05-04 | [
[
"Han",
"Muxin",
""
],
[
"Kaminski",
"Wojciech",
""
],
[
"Liu",
"Hongguang",
""
]
] | This work focuses on Conrady-Hnybida's 4-dimensional extended spinfoam model with timelike polyhedra, while we restrict all faces to be spacelike. Firstly, we prove the absolute convergence of the vertex amplitude with timelike polyhedra, when SU(1,1) boundary states are coherent states or the canonical basis, or their finite linear combinations. Secondly, based on the finite vertex amplitude and a proper prescription of the SU(1,1) intertwiner space, we construct the extended spinfoam amplitude on arbitrary cellular complex, taking into account the sum over SU(1,1) intertwiners of internal timelike polyhedra. We observe that the sum over SU(1,1) intertwiners is infinite for the internal timelike polyhedron that has at least 2 future-pointing and 2 past-pointing face-normals. In order to regularize the possible divergence from summing over SU(1,1) intertwiners, we develop a quantum cut-off scheme based on the eigenvalue of the ``shadow operator''. The spinfoam amplitude with timelike internal polyhedra (and spacelike faces) is finite, when 2 types of cut-offs are imposed: one is imposed on $j$ the eigenvalue of area operator, the other is imposed on the eigenvalue of shadow operator for every internal timelike polyhedron that has at least 2 future-pointing and 2 past-pointing face-normals. |
1610.00244 | Antoine Folacci | Andrei Belokogne, Antoine Folacci and Julien Queva | Stueckelberg massive electromagnetism in de Sitter and anti-de Sitter
spacetimes: Two-point functions and renormalized stress-energy tensors | v2:Typos corrected. Minor changes to match the published version | Phys. Rev. D 94, 105028 (2016) | 10.1103/PhysRevD.94.105028 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | By considering Hadamard vacuum states, we first construct the two-point
functions associated with Stueckelberg massive electromagnetism in de Sitter
and anti-de Sitter spacetimes. Then, from the general formalism developed in
[A. Belokogne and A. Folacci, Phys. Rev. D \textbf{93}, 044063 (2016)], we
obtain an exact analytical expression for the vacuum expectation value of the
renormalized stress-energy tensor of the massive vector field propagating in
these maximally symmetric spacetimes.
| [
{
"created": "Sun, 2 Oct 2016 08:45:46 GMT",
"version": "v1"
},
{
"created": "Wed, 23 Nov 2016 15:06:48 GMT",
"version": "v2"
}
] | 2016-12-07 | [
[
"Belokogne",
"Andrei",
""
],
[
"Folacci",
"Antoine",
""
],
[
"Queva",
"Julien",
""
]
] | By considering Hadamard vacuum states, we first construct the two-point functions associated with Stueckelberg massive electromagnetism in de Sitter and anti-de Sitter spacetimes. Then, from the general formalism developed in [A. Belokogne and A. Folacci, Phys. Rev. D \textbf{93}, 044063 (2016)], we obtain an exact analytical expression for the vacuum expectation value of the renormalized stress-energy tensor of the massive vector field propagating in these maximally symmetric spacetimes. |
gr-qc/9607077 | Dominik Schwarz | Dominik J. Schwarz (ETH-Zuerich) | Cosmological Perturbations of Ultrarelativistic Plasmas | talk given at Journees Relativistes '96 (Ascona, Switzerland), 4
pages, LaTeX, two Postscript figures | Helv.Phys.Acta 69:194-197,1996 | null | ETH-TH/96-24 | gr-qc astro-ph | null | Scalar cosmological perturbations of a weakly self-interacting plasma mixed
with a perfect radiation fluid are investigated. Effects of this plasma are
considered through order $\lambda^{3/2}$ of perturbative thermal-field-theory
in the radiation dominated universe. The breakdown of thermal perturbation
theory at vastly subhorizon scales is circumvented by a Pad\'e approximant
solution. Compared to collisionless plasmas the phase speed and subhorizon
damping of the plasma density perturbations are changed. An example for a
self-interacting thermal field is provided by the neutrinos with effective
4-fermion interactions.
| [
{
"created": "Wed, 31 Jul 1996 14:42:14 GMT",
"version": "v1"
}
] | 2011-04-15 | [
[
"Schwarz",
"Dominik J.",
"",
"ETH-Zuerich"
]
] | Scalar cosmological perturbations of a weakly self-interacting plasma mixed with a perfect radiation fluid are investigated. Effects of this plasma are considered through order $\lambda^{3/2}$ of perturbative thermal-field-theory in the radiation dominated universe. The breakdown of thermal perturbation theory at vastly subhorizon scales is circumvented by a Pad\'e approximant solution. Compared to collisionless plasmas the phase speed and subhorizon damping of the plasma density perturbations are changed. An example for a self-interacting thermal field is provided by the neutrinos with effective 4-fermion interactions. |
2203.07780 | Noa Zilberman | Noa Zilberman, Marc Casals, Amos Ori and Adrian C. Ottewill | Two-point function of a quantum scalar field in the interior region of a
Kerr black hole | null | null | 10.1103/PhysRevD.106.125011 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | Quantum field effects on a classical background spacetime may be obtained
from the semiclassical equations of General Relativity with the expectation
value of the stress-energy tensor of the quantum field as a source. This
expectation value can be calculated from Hadamard's elementary two-point
function, which in practice is given in terms of sums of products of field
modes evaluated at two spacetime points. We derive expressions for the
two-point function for a massless scalar field in the Unruh state on a Kerr
black hole spacetime. Our main result in this paper is a novel expression valid
when the two points lie inside the black hole; we also (re-)derive, using a new
method, the known expression valid when the two points lie outside the black
hole. We achieve these expressions by finding relationships between Unruh
modes, defined in terms of the retarded Kruskal coordinate, and Eddington
modes, defined in terms of the Eddington coordinates. While our starting
expression for the two-point function is written in terms of the Unruh modes,
we give our final expression in terms of the Eddington modes, which have the
computational advantage that they decompose into factors that obey ordinary
differential equations. In an appendix we also derive expressions for the bare
mode contributions to the flux components of the stress-energy tensor for a
minimally-coupled massless scalar field inside the black hole. Our results thus
lay the groundwork for future calculations of quantum effects inside a Kerr
black hole.
| [
{
"created": "Tue, 15 Mar 2022 11:01:49 GMT",
"version": "v1"
}
] | 2023-01-04 | [
[
"Zilberman",
"Noa",
""
],
[
"Casals",
"Marc",
""
],
[
"Ori",
"Amos",
""
],
[
"Ottewill",
"Adrian C.",
""
]
] | Quantum field effects on a classical background spacetime may be obtained from the semiclassical equations of General Relativity with the expectation value of the stress-energy tensor of the quantum field as a source. This expectation value can be calculated from Hadamard's elementary two-point function, which in practice is given in terms of sums of products of field modes evaluated at two spacetime points. We derive expressions for the two-point function for a massless scalar field in the Unruh state on a Kerr black hole spacetime. Our main result in this paper is a novel expression valid when the two points lie inside the black hole; we also (re-)derive, using a new method, the known expression valid when the two points lie outside the black hole. We achieve these expressions by finding relationships between Unruh modes, defined in terms of the retarded Kruskal coordinate, and Eddington modes, defined in terms of the Eddington coordinates. While our starting expression for the two-point function is written in terms of the Unruh modes, we give our final expression in terms of the Eddington modes, which have the computational advantage that they decompose into factors that obey ordinary differential equations. In an appendix we also derive expressions for the bare mode contributions to the flux components of the stress-energy tensor for a minimally-coupled massless scalar field inside the black hole. Our results thus lay the groundwork for future calculations of quantum effects inside a Kerr black hole. |
2102.06824 | Alexey Bobrick | Alexey Bobrick, Gianni Martire | Introducing Physical Warp Drives | Accepted in CQG, comments welcome | null | 10.1088/1361-6382/abdf6e | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Alcubierre warp drive is an exotic solution in general relativity. It
allows for superluminal travel at the cost of enormous amounts of matter with
negative mass density. For this reason, the Alcubierre warp drive has been
widely considered unphysical. In this study, we develop a model of a general
warp drive spacetime in classical relativity that encloses all existing warp
drive definitions and allows for new metrics without the most serious issues
present in the Alcubierre solution. We present the first general model for
subluminal positive-energy, spherically symmetric warp drives; construct
superluminal warp-drive solutions which satisfy quantum inequalities; provide
optimizations for the Alcubierre metric that decrease the negative energy
requirements by two orders of magnitude; and introduce a warp drive spacetime
in which space capacity and the rate of time can be chosen in a controlled
manner. Conceptually, we demonstrate that any warp drive, including the
Alcubierre drive, is a shell of regular or exotic material moving inertially
with a certain velocity. Therefore, any warp drive requires propulsion. We show
that a class of subluminal, spherically symmetric warp drive spacetimes, at
least in principle, can be constructed based on the physical principles known
to humanity today.
| [
{
"created": "Fri, 12 Feb 2021 23:58:39 GMT",
"version": "v1"
},
{
"created": "Wed, 17 Feb 2021 13:48:39 GMT",
"version": "v2"
}
] | 2021-02-18 | [
[
"Bobrick",
"Alexey",
""
],
[
"Martire",
"Gianni",
""
]
] | The Alcubierre warp drive is an exotic solution in general relativity. It allows for superluminal travel at the cost of enormous amounts of matter with negative mass density. For this reason, the Alcubierre warp drive has been widely considered unphysical. In this study, we develop a model of a general warp drive spacetime in classical relativity that encloses all existing warp drive definitions and allows for new metrics without the most serious issues present in the Alcubierre solution. We present the first general model for subluminal positive-energy, spherically symmetric warp drives; construct superluminal warp-drive solutions which satisfy quantum inequalities; provide optimizations for the Alcubierre metric that decrease the negative energy requirements by two orders of magnitude; and introduce a warp drive spacetime in which space capacity and the rate of time can be chosen in a controlled manner. Conceptually, we demonstrate that any warp drive, including the Alcubierre drive, is a shell of regular or exotic material moving inertially with a certain velocity. Therefore, any warp drive requires propulsion. We show that a class of subluminal, spherically symmetric warp drive spacetimes, at least in principle, can be constructed based on the physical principles known to humanity today. |
1802.01543 | Ilya Vilensky | Jonathan Engle, Ilya Vilensky | Deriving loop quantum cosmology dynamics from diffeomorphism invariance | 34 pages, improved presentation by imposing covariance under
non-canonical diffeomorphisms | Phys. Rev. D 98, 023505 (2018) | 10.1103/PhysRevD.98.023505 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We use the requirement of diffeomorphism invariance in the Bianchi I context
to derive the form of the quantum Hamiltonian constraint. After imposing the
correct classical behavior and making a certain minimality assumption, together
with a certain restriction to "planar loops", we then obtain a unique
expression for the quantum Hamiltonian operator for Bianchi I to both leading
and subleading orders in $\hbar$. Specifically, this expression is found to
exactly match the form proposed by Ashtekar and Wilson-Ewing in the loop
quantum cosmology (LQC) literature. Furthermore, by using the projection map
from the quantum states of the Bianchi I model to the states of the isotropic
model, we constrain the dynamics also in the homogeneous isotropic case, and
obtain, again to both leading and subleading order in $\hbar$, a quantum
constraint which exactly matches the standard `improved dynamics' of Ashtekar,
Pawlowski and Singh. This result in the isotropic case does not require a
restriction to planar loops, but only the minimality assumption. Our results
strengthen confidence in LQC dynamics and its observational predictions as
consequences of more basic fundamental principles. Of the assumptions made in
the isotropic case, the only one not rigidly determined by physical principle
is the minimality principle, our work also shows the exact freedom allowed when
this assumption is relaxed.
| [
{
"created": "Mon, 5 Feb 2018 18:10:22 GMT",
"version": "v1"
},
{
"created": "Sat, 26 May 2018 01:50:37 GMT",
"version": "v2"
}
] | 2018-07-11 | [
[
"Engle",
"Jonathan",
""
],
[
"Vilensky",
"Ilya",
""
]
] | We use the requirement of diffeomorphism invariance in the Bianchi I context to derive the form of the quantum Hamiltonian constraint. After imposing the correct classical behavior and making a certain minimality assumption, together with a certain restriction to "planar loops", we then obtain a unique expression for the quantum Hamiltonian operator for Bianchi I to both leading and subleading orders in $\hbar$. Specifically, this expression is found to exactly match the form proposed by Ashtekar and Wilson-Ewing in the loop quantum cosmology (LQC) literature. Furthermore, by using the projection map from the quantum states of the Bianchi I model to the states of the isotropic model, we constrain the dynamics also in the homogeneous isotropic case, and obtain, again to both leading and subleading order in $\hbar$, a quantum constraint which exactly matches the standard `improved dynamics' of Ashtekar, Pawlowski and Singh. This result in the isotropic case does not require a restriction to planar loops, but only the minimality assumption. Our results strengthen confidence in LQC dynamics and its observational predictions as consequences of more basic fundamental principles. Of the assumptions made in the isotropic case, the only one not rigidly determined by physical principle is the minimality principle, our work also shows the exact freedom allowed when this assumption is relaxed. |
2012.11959 | Viktor Gakis | Gianbattista-Piero Nicosia, Jackson Levi Said and Viktor Gakis | Generalised Proca Theories in Teleparallel Gravity | 19 pages | The European Physical Journal Plus volume 136 (2021) | 10.1140/epjp/s13360-021-01133-4 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | Generalised Proca theories of gravity represent an interesting class of
vector-tensor theories where only three propagating degrees of freedom are
present. In this work, we propose a new teleparallel gravity analog to Proca
theories where the generalised Proca framework is extended due to the lower
order nature of torsion based gravity. We develop a new action contribution and
explore the example of the Friedmann equations in this regime. We find that
teleparallel Proca theories offer the possibility of a much larger class of
models in which do have an impact on background cosmology.
| [
{
"created": "Tue, 22 Dec 2020 12:24:47 GMT",
"version": "v1"
},
{
"created": "Thu, 24 Mar 2022 15:38:08 GMT",
"version": "v2"
}
] | 2022-03-25 | [
[
"Nicosia",
"Gianbattista-Piero",
""
],
[
"Said",
"Jackson Levi",
""
],
[
"Gakis",
"Viktor",
""
]
] | Generalised Proca theories of gravity represent an interesting class of vector-tensor theories where only three propagating degrees of freedom are present. In this work, we propose a new teleparallel gravity analog to Proca theories where the generalised Proca framework is extended due to the lower order nature of torsion based gravity. We develop a new action contribution and explore the example of the Friedmann equations in this regime. We find that teleparallel Proca theories offer the possibility of a much larger class of models in which do have an impact on background cosmology. |
2306.11926 | Israel Quiros | Israel Quiros | Comment on "Dark matter as a Weyl geometric effect" | 3 pages without figures. Improved and shortened version, focused
exclusively in the demonstration that the solution found by the authors of
the PRD paper is wrong | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this note we comment on a recent attempt by P. Burikham, T. Harko, K.
Pimsamarn and S. Shahidi [Phys. Rev. D {\bf 107}, 064008 (2023)] to explain the
galactic rotation curves as the result of the motion of time-like test
particles in the Weyl geometric theory of gravity. We show that the static,
spherically symmetric solution found by the authors, which could be the basis
of an alternative explanation of the galactic rotation curves, is wrong.
| [
{
"created": "Tue, 20 Jun 2023 22:23:43 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Aug 2023 07:28:51 GMT",
"version": "v2"
},
{
"created": "Tue, 15 Aug 2023 15:52:36 GMT",
"version": "v3"
}
] | 2023-08-16 | [
[
"Quiros",
"Israel",
""
]
] | In this note we comment on a recent attempt by P. Burikham, T. Harko, K. Pimsamarn and S. Shahidi [Phys. Rev. D {\bf 107}, 064008 (2023)] to explain the galactic rotation curves as the result of the motion of time-like test particles in the Weyl geometric theory of gravity. We show that the static, spherically symmetric solution found by the authors, which could be the basis of an alternative explanation of the galactic rotation curves, is wrong. |
gr-qc/0604084 | James Vickers | R. A. d'Inverno, P. Lambert, J. A. Vickers | Hamiltonian analysis of the double null 2+2 decomposition of General
Relativity expressed in terms of self-dual bivectors | 12 pages, LaTeX, uses iopart.cls, submitted to Class. Quantum Grav | Class.Quant.Grav. 23 (2006) 4511-4522 | 10.1088/0264-9381/23/13/014 | null | gr-qc | null | In this paper we obtain a 2+2 double null Hamiltonian description of General
Relativity using only the (complex) SO(3) connection and the components of the
complex densitised self-dual bivectors. We carry out the general canonical
analysis of this system and obtain the first class constraint algebra entirely
in terms of the self-dual variables. The first class algebra forms a Lie
algebra and all the first class constraints have a simple geometrical
interpretation.
| [
{
"created": "Thu, 20 Apr 2006 08:33:23 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"d'Inverno",
"R. A.",
""
],
[
"Lambert",
"P.",
""
],
[
"Vickers",
"J. A.",
""
]
] | In this paper we obtain a 2+2 double null Hamiltonian description of General Relativity using only the (complex) SO(3) connection and the components of the complex densitised self-dual bivectors. We carry out the general canonical analysis of this system and obtain the first class constraint algebra entirely in terms of the self-dual variables. The first class algebra forms a Lie algebra and all the first class constraints have a simple geometrical interpretation. |
1211.6022 | Jose M. M. Senovilla | Jos\'e M. M. Senovilla | Remarks on the stability operator for MOTS | 4 pages, no figures, contribution to the Proceedings of the Spanish
Relativity Meeting in Portugal ERE2012, held in Guimar\~aes, 3--7 Septmber
2012 | null | null | null | gr-qc math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Small deformations of marginally outer trapped surfaces (MOTS) are studied by
using the stability operator introduced by Andersson-Mars-Simon. Novel formulae
for the principal eigenvalue are presented. A characterization of the many
marginally outer trapped tubes (MOTT) passing through a given MOTS is given,
and the possibility of selecting a privileged MOTT is discussed. This is
related to the concept of `core' of a black hole: a minimal region that one
should remove from the spacetime in order to get rid of all possible closed
trapped surfaces. In spherical symmetry one can prove that the spherical MOTT
is the boundary of a core. I argue how similar results may hold in general
spacetimes.
| [
{
"created": "Mon, 26 Nov 2012 16:52:09 GMT",
"version": "v1"
}
] | 2012-11-27 | [
[
"Senovilla",
"José M. M.",
""
]
] | Small deformations of marginally outer trapped surfaces (MOTS) are studied by using the stability operator introduced by Andersson-Mars-Simon. Novel formulae for the principal eigenvalue are presented. A characterization of the many marginally outer trapped tubes (MOTT) passing through a given MOTS is given, and the possibility of selecting a privileged MOTT is discussed. This is related to the concept of `core' of a black hole: a minimal region that one should remove from the spacetime in order to get rid of all possible closed trapped surfaces. In spherical symmetry one can prove that the spherical MOTT is the boundary of a core. I argue how similar results may hold in general spacetimes. |
1803.01624 | Jorma Louko | Robert Benkel, Jishnu Bhattacharyya, Jorma Louko, David Mattingly,
Thomas P. Sotiriou | Dynamical obstruction to perpetual motion from Lorentz-violating black
holes | 10 pages. v2: minor additions to discussion, version accepted in PRD | Phys. Rev. D 98, 024034 (2018) | 10.1103/PhysRevD.98.024034 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Black holes in Lorentz-violating theories have been claimed to violate the
second law of thermodynamics by perpetual motion energy extraction. We revisit
this question for a Penrose splitting process in a spherically symmetric
setting with two species of particles that move on radial geodesics that extend
to infinity. We show that energy extraction by this process cannot happen in
any theory in which gravity is attractive, in the sense of a geometric
inequality that we describe. This inequality is satisfied by all known
Einstein-\ae{}ther and Ho\v{r}ava black hole solutions.
| [
{
"created": "Mon, 5 Mar 2018 12:18:00 GMT",
"version": "v1"
},
{
"created": "Tue, 24 Jul 2018 17:26:25 GMT",
"version": "v2"
}
] | 2018-07-25 | [
[
"Benkel",
"Robert",
""
],
[
"Bhattacharyya",
"Jishnu",
""
],
[
"Louko",
"Jorma",
""
],
[
"Mattingly",
"David",
""
],
[
"Sotiriou",
"Thomas P.",
""
]
] | Black holes in Lorentz-violating theories have been claimed to violate the second law of thermodynamics by perpetual motion energy extraction. We revisit this question for a Penrose splitting process in a spherically symmetric setting with two species of particles that move on radial geodesics that extend to infinity. We show that energy extraction by this process cannot happen in any theory in which gravity is attractive, in the sense of a geometric inequality that we describe. This inequality is satisfied by all known Einstein-\ae{}ther and Ho\v{r}ava black hole solutions. |
2404.15408 | Rossella Gamba | Rossella Gamba, Danilo Chiaramello and Sayan Neogi | Towards efficient Effective One Body models for generic, non-planar
orbits | 17 pages, 13 figures; version accepted for publication | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Complete waveform models able to account for arbitrary non-planar orbits
represent a holy grail in current gravitational-wave astronomy. Here, we take a
step towards this direction and present a simple yet efficient prescription to
obtain the evolution of the spin vectors and of the orbital angular momentum
along non-circularized orbits, that can be applied to any eccentric
aligned-spins waveform model. The scheme employed is motivated by insights
gained from the post-Newtonian (PN) regime. We investigate the phenomenology of
the Euler angles characterizing the time-dependent rotation that connects the
co-precessing frame to the inertial one, gauging the importance of non-circular
terms in the evolution of the spins of a precessing binary. We demonstrate that
such terms are largely negligible, irrespectively of the details of the orbit.
Such insights are confirmed by studying the radiation-frame of a few eccentric,
precessing numerical relativity (NR) simulations. Our investigations confirm
that the usual "twisting" technique employed for quasi-spherical systems can be
safely applied to non-circularized binaries. By then augmenting a
state-of-the-art Effective-One-Body (EOB) model for non-circular planar orbits
with the prescription discussed, we obtain an inspiral-merger-ringdown (IMR)
model for eccentric, precessing binary black holes (BBHs). We validate the
model in the quasi-spherical limit via mismatches and present one phasing
comparison against a precessing, eccentric simulation from the RIT catalog.
| [
{
"created": "Tue, 23 Apr 2024 18:00:22 GMT",
"version": "v1"
},
{
"created": "Wed, 26 Jun 2024 10:50:55 GMT",
"version": "v2"
}
] | 2024-06-27 | [
[
"Gamba",
"Rossella",
""
],
[
"Chiaramello",
"Danilo",
""
],
[
"Neogi",
"Sayan",
""
]
] | Complete waveform models able to account for arbitrary non-planar orbits represent a holy grail in current gravitational-wave astronomy. Here, we take a step towards this direction and present a simple yet efficient prescription to obtain the evolution of the spin vectors and of the orbital angular momentum along non-circularized orbits, that can be applied to any eccentric aligned-spins waveform model. The scheme employed is motivated by insights gained from the post-Newtonian (PN) regime. We investigate the phenomenology of the Euler angles characterizing the time-dependent rotation that connects the co-precessing frame to the inertial one, gauging the importance of non-circular terms in the evolution of the spins of a precessing binary. We demonstrate that such terms are largely negligible, irrespectively of the details of the orbit. Such insights are confirmed by studying the radiation-frame of a few eccentric, precessing numerical relativity (NR) simulations. Our investigations confirm that the usual "twisting" technique employed for quasi-spherical systems can be safely applied to non-circularized binaries. By then augmenting a state-of-the-art Effective-One-Body (EOB) model for non-circular planar orbits with the prescription discussed, we obtain an inspiral-merger-ringdown (IMR) model for eccentric, precessing binary black holes (BBHs). We validate the model in the quasi-spherical limit via mismatches and present one phasing comparison against a precessing, eccentric simulation from the RIT catalog. |
2206.01389 | Erik Jim\'enez-V\'azquez | Erik Jimenez-Vazquez, Miguel Alcubierre | Critical gravitational collapse of a massive complex scalar field | null | null | 10.1103/PhysRevD.106.044071 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the critical collapse of a massive complex scalar field coupled
minimally to gravity. Taking as initial data a simple gaussian pulse with a
shape similar to the harmonic ansatz for boson stars, we obtain critical
collapse of type type I and II when varying the gaussian width $\sigma$. For
$\sigma \leq 0.5$ we find collapse of type II with a critical exponent
$\gamma=0.38\pm0.01$ and an echoing period $\Delta=3.4\pm0.1$. These values are
very similar to the known results for a real massless scalar field. On the
other hand, for $\sigma \geq 2.5$ we obtain collapse of type I. In this case we
find that the critical solutions turn out to be an unstable boson stars in the
ground state: all the data obtained from our simulations can be contrasted with
the characteristic values for unstable boson stars and their corresponding
Lyapunov exponents.
| [
{
"created": "Fri, 3 Jun 2022 04:26:57 GMT",
"version": "v1"
},
{
"created": "Wed, 17 Aug 2022 18:34:56 GMT",
"version": "v2"
}
] | 2022-09-07 | [
[
"Jimenez-Vazquez",
"Erik",
""
],
[
"Alcubierre",
"Miguel",
""
]
] | We study the critical collapse of a massive complex scalar field coupled minimally to gravity. Taking as initial data a simple gaussian pulse with a shape similar to the harmonic ansatz for boson stars, we obtain critical collapse of type type I and II when varying the gaussian width $\sigma$. For $\sigma \leq 0.5$ we find collapse of type II with a critical exponent $\gamma=0.38\pm0.01$ and an echoing period $\Delta=3.4\pm0.1$. These values are very similar to the known results for a real massless scalar field. On the other hand, for $\sigma \geq 2.5$ we obtain collapse of type I. In this case we find that the critical solutions turn out to be an unstable boson stars in the ground state: all the data obtained from our simulations can be contrasted with the characteristic values for unstable boson stars and their corresponding Lyapunov exponents. |
2308.10184 | Xiangdong Zhang | Xiangdong Zhang | Loop quantum black hole | A mini review, 15 pages | Universe 2023, 9(7), 313 | 10.3390/universe9070313 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | In the last decades, progress on the quantization of black holes using
techniques developed in loop quantum cosmology has received increasing
attention. Due to the quantum geometry effect, the resulting quantum corrected
black hole is free of singularity. The quantization scheme can be roughly
divided into four types, that is 1. $\mu_0$-scheme, 2. $\bar{\mu}$-scheme, 3.
generalized $\mu_0$-scheme, 4. quantum collapsing model. This paper provides an
introduction of the loop quantum black hole models and a summary of the
progress made in this field, as well as the quantum effective dynamics and
physical applications of these models.
| [
{
"created": "Sun, 20 Aug 2023 07:24:15 GMT",
"version": "v1"
}
] | 2023-08-22 | [
[
"Zhang",
"Xiangdong",
""
]
] | In the last decades, progress on the quantization of black holes using techniques developed in loop quantum cosmology has received increasing attention. Due to the quantum geometry effect, the resulting quantum corrected black hole is free of singularity. The quantization scheme can be roughly divided into four types, that is 1. $\mu_0$-scheme, 2. $\bar{\mu}$-scheme, 3. generalized $\mu_0$-scheme, 4. quantum collapsing model. This paper provides an introduction of the loop quantum black hole models and a summary of the progress made in this field, as well as the quantum effective dynamics and physical applications of these models. |
gr-qc/9404059 | Jorge Pullin | Rodolfo Gambini, Alcides Garat and Jorge Pullin | The constraint algebra of quantum gravity in the loop representation | 18 pages, Revtex, no figures, CGPG-94/4-3 | Int.J.Mod.Phys. D4 (1995) 589-616 | 10.1142/S0218271895000417 | null | gr-qc | null | We study the algebra of constraints of quantum gravity in the loop
representation based on Ashtekar's new variables. We show by direct computation
that the quantum commutator algebra reproduces the classical Poisson bracket
one, in the limit in which regulators are removed. The calculation illustrates
the use of several computational techniques for the loop representation.
| [
{
"created": "Thu, 28 Apr 1994 16:05:58 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Gambini",
"Rodolfo",
""
],
[
"Garat",
"Alcides",
""
],
[
"Pullin",
"Jorge",
""
]
] | We study the algebra of constraints of quantum gravity in the loop representation based on Ashtekar's new variables. We show by direct computation that the quantum commutator algebra reproduces the classical Poisson bracket one, in the limit in which regulators are removed. The calculation illustrates the use of several computational techniques for the loop representation. |
gr-qc/0308031 | Patricio S. Letelier | Daniel Vogt and Patricio S. Letelier | Exact General Relativistic Perfect Fluid Disks with Halos | 22 pages, 25 eps.figs, RevTex. Phys. Rev. D to appear | Phys.Rev. D68 (2003) 084010 | 10.1103/PhysRevD.68.084010 | null | gr-qc astro-ph | null | Using the well-known ``displace, cut and reflect'' method used to generate
disks from given solutions of Einstein field equations, we construct static
disks made of perfect fluid based on vacuum Schwarzschild's solution in
isotropic coordinates. The same method is applied to different exactsolutions
to the Einstein'sequations that represent static spheres of perfect fluids. We
construct several models of disks with axially symmetric perfect fluid halos.
All disks have some common features: surface energy density and pressures
decrease monotonically and rapidly with radius. As the ``cut'' parameter $a$
decreases, the disks become more relativistic, with surface energy density and
pressure more concentrated near the center. Also regions of unstable circular
orbits are more likely to appear for high relativistic disks. Parameters can be
chosen so that the sound velocity in the fluid and the tangential velocity of
test particles in circular motion are less then the velocity of light. This
tangential velocity first increases with radius and reaches a maximum.
| [
{
"created": "Mon, 11 Aug 2003 14:21:37 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Vogt",
"Daniel",
""
],
[
"Letelier",
"Patricio S.",
""
]
] | Using the well-known ``displace, cut and reflect'' method used to generate disks from given solutions of Einstein field equations, we construct static disks made of perfect fluid based on vacuum Schwarzschild's solution in isotropic coordinates. The same method is applied to different exactsolutions to the Einstein'sequations that represent static spheres of perfect fluids. We construct several models of disks with axially symmetric perfect fluid halos. All disks have some common features: surface energy density and pressures decrease monotonically and rapidly with radius. As the ``cut'' parameter $a$ decreases, the disks become more relativistic, with surface energy density and pressure more concentrated near the center. Also regions of unstable circular orbits are more likely to appear for high relativistic disks. Parameters can be chosen so that the sound velocity in the fluid and the tangential velocity of test particles in circular motion are less then the velocity of light. This tangential velocity first increases with radius and reaches a maximum. |
gr-qc/0609071 | Yun-Song Piao | Yun-Song Piao | Seeding of Primordial Perturbations During a Decelerated Expansion | 5 pages, 3 figures, more details and clarifications added, refs.
added, new version with 6 pages has been splitted into various sections, to
be published in PRD, v3, matched to published version | Phys.Rev.D75:063517,2007 | 10.1103/PhysRevD.75.063517 | null | gr-qc | null | A scalar field with a modified dispersion relation may seed, under certain
conditions, the primordial perturbations during a decelerated expansion. In
this note we examine whether and how these perturbations can be responsible for
the structure formation of observable universe. We discuss relevant
difficulties and possible solutions.
| [
{
"created": "Tue, 19 Sep 2006 10:38:44 GMT",
"version": "v1"
},
{
"created": "Tue, 6 Mar 2007 05:11:46 GMT",
"version": "v2"
},
{
"created": "Wed, 9 May 2007 06:35:59 GMT",
"version": "v3"
}
] | 2008-11-26 | [
[
"Piao",
"Yun-Song",
""
]
] | A scalar field with a modified dispersion relation may seed, under certain conditions, the primordial perturbations during a decelerated expansion. In this note we examine whether and how these perturbations can be responsible for the structure formation of observable universe. We discuss relevant difficulties and possible solutions. |
1710.01357 | Sk Jahanur Hoque | Sk Jahanur Hoque and Ankit Aggarwal | Quadrupolar power radiation by a binary system in de Sitter Background | Version accepted for publication in IJMPD. Angular momentum loss and
evolution of orbital parameters are added. 24 pages, 2 figures | International Journal of Modern Physics D Vol. 28 (2019) 1950025 | 10.1142/S0218271819500251 | IMSc/2017/10/08 | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Cosmological observations over past couple of decades favor our universe with
a tiny positive cosmological constant. Presence of cosmological constant not
only imposes theoretical challenges in gravitational wave physics, it has also
observational relevance. Inclusion of cosmological constant in linearized
theory of gravitational waves modifies the power radiated quadrupole formula.
There are two types of observations which can be impacted by the modified
quadrupole formula. One is the orbital decay of an inspiraling binary and other
is the modification of the waveform at the detector. Modelling a compact binary
system in an elliptic orbit on de Sitter background we obtain energy and
angular momentum radiation due to emission of gravitational waves. We also
investigate evolution of orbital parameters under back reaction and its impact
on orbital decay rate. In the limit to circular orbit our result matches to
that obtained in ref. [26].
| [
{
"created": "Tue, 3 Oct 2017 19:33:19 GMT",
"version": "v1"
},
{
"created": "Tue, 23 Oct 2018 16:52:09 GMT",
"version": "v2"
}
] | 2018-10-24 | [
[
"Hoque",
"Sk Jahanur",
""
],
[
"Aggarwal",
"Ankit",
""
]
] | Cosmological observations over past couple of decades favor our universe with a tiny positive cosmological constant. Presence of cosmological constant not only imposes theoretical challenges in gravitational wave physics, it has also observational relevance. Inclusion of cosmological constant in linearized theory of gravitational waves modifies the power radiated quadrupole formula. There are two types of observations which can be impacted by the modified quadrupole formula. One is the orbital decay of an inspiraling binary and other is the modification of the waveform at the detector. Modelling a compact binary system in an elliptic orbit on de Sitter background we obtain energy and angular momentum radiation due to emission of gravitational waves. We also investigate evolution of orbital parameters under back reaction and its impact on orbital decay rate. In the limit to circular orbit our result matches to that obtained in ref. [26]. |
gr-qc/9809066 | Jerzy Kowalczynski | J.K. Kowalczynski (Instute of Physics, Polish Academy of Sciences) | An Unexpected Electrovac Solution with the Negative Cosmological
Constant | 8 pages, LaTeX 2e, no figures. The present (second) version is
derived from the first one by adding two references (here Refs. [15,16]) and
comments on the Bertotti solution and on its special cases. I made no
submission for publication when it appeared that the solution in question is
a special case of the Bertotti solution | null | null | null | gr-qc | null | An exact solution of the current-free Einstein-Maxwell equations with the
cosmological constant is presented. The solution is of Petrov type D, includes
the negative cosmological constant, and could be a ``background addition'' to
the present-day models of the universe. It has a surprising property such that
its electromagnetic field and cosmological constant are interdependent (this
constant is proportional to the energy density of this field), which may
suggest a new way of measuring the constant in question. The solution describes
a constant electromagnetic background with a preferred direction in the
universe, and defines the entire lifetime of the universe as a simple function
of the negative cosmological constant. According to our solution the absolute
value of this constant should be considerably lower than that recently
estimated, when astrophysical data are taken into account. Our solution is a
special case of that published by Bertotti in 1959. His solution (in terms of
which the cosmological constant and the background electromagnetic field are
independent) and its two other special cases, i.e. the conformally flat
Robinson solution (1959) and the one which is the counterpart of our solution
with the positive cosmological constant, are briefly discussed.
| [
{
"created": "Wed, 23 Sep 1998 16:08:04 GMT",
"version": "v1"
},
{
"created": "Mon, 13 Nov 2000 14:30:29 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Kowalczynski",
"J. K.",
"",
"Instute of Physics, Polish Academy of Sciences"
]
] | An exact solution of the current-free Einstein-Maxwell equations with the cosmological constant is presented. The solution is of Petrov type D, includes the negative cosmological constant, and could be a ``background addition'' to the present-day models of the universe. It has a surprising property such that its electromagnetic field and cosmological constant are interdependent (this constant is proportional to the energy density of this field), which may suggest a new way of measuring the constant in question. The solution describes a constant electromagnetic background with a preferred direction in the universe, and defines the entire lifetime of the universe as a simple function of the negative cosmological constant. According to our solution the absolute value of this constant should be considerably lower than that recently estimated, when astrophysical data are taken into account. Our solution is a special case of that published by Bertotti in 1959. His solution (in terms of which the cosmological constant and the background electromagnetic field are independent) and its two other special cases, i.e. the conformally flat Robinson solution (1959) and the one which is the counterpart of our solution with the positive cosmological constant, are briefly discussed. |
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