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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
gr-qc/0510066 | Vilson T. Zanchin | Alex S. Miranda and Vilson T. Zanchin | Quasinormal modes of plane-symmetric anti-de Sitter black holes: a
complete analysis of the gravitational perturbations | Added new material on the asymptotic behavior of QNMs | Phys.Rev. D73 (2006) 064034 | 10.1103/PhysRevD.73.064034 | null | gr-qc hep-th | null | We study in detail the quasinormal modes of linear gravitational
perturbations of plane-symmetric anti-de Sitter black holes. The wave equations
are obtained by means of the Newman-Penrose formalism and the Chandrasekhar
transformation theory. We show that oscillatory modes decay exponentially with
time such that these black holes are stable against gravitational
perturbations. Our numerical results show that in the large (small) black hole
regime the frequencies of the ordinary quasinormal modes are proportional to
the horizon radius $r_{+}$ (wave number $k$). The frequency of the purely
damped mode is very close to the algebraically special frequency in the small
horizon limit, and goes as $ik^{2}/3r_{+}$ in the opposite limit. This result
is confirmed by an analytical method based on the power series expansion of the
frequency in terms of the horizon radius. The same procedure applied to the
Schwarzschild anti-de Sitter spacetime proves that the purely damped frequency
goes as $i(l-1)(l+2)/3r_{+}$, where $l$ is the quantum number characterizing
the angular distribution. Finally, we study the limit of high overtones and
find that the frequencies become evenly spaced in this regime. The spacing of
the frequency per unit horizon radius seems to be a universal quantity, in the
sense that it is independent of the wave number, perturbation parity and black
hole size.
| [
{
"created": "Thu, 13 Oct 2005 23:21:19 GMT",
"version": "v1"
},
{
"created": "Sun, 16 Oct 2005 09:39:18 GMT",
"version": "v2"
},
{
"created": "Thu, 30 Mar 2006 19:54:31 GMT",
"version": "v3"
}
] | 2016-03-25 | [
[
"Miranda",
"Alex S.",
""
],
[
"Zanchin",
"Vilson T.",
""
]
] | We study in detail the quasinormal modes of linear gravitational perturbations of plane-symmetric anti-de Sitter black holes. The wave equations are obtained by means of the Newman-Penrose formalism and the Chandrasekhar transformation theory. We show that oscillatory modes decay exponentially with time such that these black holes are stable against gravitational perturbations. Our numerical results show that in the large (small) black hole regime the frequencies of the ordinary quasinormal modes are proportional to the horizon radius $r_{+}$ (wave number $k$). The frequency of the purely damped mode is very close to the algebraically special frequency in the small horizon limit, and goes as $ik^{2}/3r_{+}$ in the opposite limit. This result is confirmed by an analytical method based on the power series expansion of the frequency in terms of the horizon radius. The same procedure applied to the Schwarzschild anti-de Sitter spacetime proves that the purely damped frequency goes as $i(l-1)(l+2)/3r_{+}$, where $l$ is the quantum number characterizing the angular distribution. Finally, we study the limit of high overtones and find that the frequencies become evenly spaced in this regime. The spacing of the frequency per unit horizon radius seems to be a universal quantity, in the sense that it is independent of the wave number, perturbation parity and black hole size. |
1907.13354 | Vittorio De Falco Dr | Vittorio De Falco, Emmanuele Battista | Analytical Rayleigh potential for the general relativistic
Poynting-Robertson effect | 4,6 pages, 0 figures, 0 tables. Accepted in Europhysics Letters in
date 31 July 2019 | null | 10.1209/0295-5075/127/30006 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We determine the analytic expression of the Rayleigh potential associated to
the general relativistic Poynting-Robertson effect. This constitutes the first
example of a physical dissipative system treated analytically in General
Relativity. The employed approach and further implications are discussed.
| [
{
"created": "Wed, 31 Jul 2019 07:49:45 GMT",
"version": "v1"
}
] | 2019-09-12 | [
[
"De Falco",
"Vittorio",
""
],
[
"Battista",
"Emmanuele",
""
]
] | We determine the analytic expression of the Rayleigh potential associated to the general relativistic Poynting-Robertson effect. This constitutes the first example of a physical dissipative system treated analytically in General Relativity. The employed approach and further implications are discussed. |
gr-qc/0211030 | Miguel S\'anchez | Antonio N. Bernal, Miguel S\'anchez (Univ. Granada) | Leibnizian, Galilean and Newtonian structures of spacetime | Minor errata corrected, to appear in J. Math. Phys.; 22 pages
including a table, Latex | J.Math.Phys. 44 (2003) 1129-1149 | 10.1063/1.1541120 | null | gr-qc math.DG | null | The following three geometrical structures on a manifold are studied in
detail: (1) Leibnizian: a non-vanishing 1-form $\Omega$ plus a Riemannian
metric $\h$ on its annhilator vector bundle. In particular, the possible
dimensions of the automorphism group of a Leibnizian G-structure are
characterized. (2) Galilean: Leibnizian structure endowed with an affine
connection $\nabla$ (gauge field) which parallelizes $\Omega$ and $\h$. Fixed
any vector field of observers Z ($\Omega (Z) = 1$), an explicit Koszul--type
formula which reconstruct bijectively all the possible $\nabla$'s from the
gravitational ${\cal G} = \nabla_Z Z$ and vorticity $\omega = rot Z/2$ fields
(plus eventually the torsion) is provided. (3) Newtonian: Galilean structure
with $\h$ flat and a field of observers Z which is inertial (its flow preserves
the Leibnizian structure and $\omega = 0$). Classical concepts in Newtonian
theory are revisited and discussed.
| [
{
"created": "Fri, 8 Nov 2002 23:14:59 GMT",
"version": "v1"
},
{
"created": "Fri, 6 Dec 2002 18:53:39 GMT",
"version": "v2"
}
] | 2015-06-25 | [
[
"Bernal",
"Antonio N.",
"",
"Univ. Granada"
],
[
"Sánchez",
"Miguel",
"",
"Univ. Granada"
]
] | The following three geometrical structures on a manifold are studied in detail: (1) Leibnizian: a non-vanishing 1-form $\Omega$ plus a Riemannian metric $\h$ on its annhilator vector bundle. In particular, the possible dimensions of the automorphism group of a Leibnizian G-structure are characterized. (2) Galilean: Leibnizian structure endowed with an affine connection $\nabla$ (gauge field) which parallelizes $\Omega$ and $\h$. Fixed any vector field of observers Z ($\Omega (Z) = 1$), an explicit Koszul--type formula which reconstruct bijectively all the possible $\nabla$'s from the gravitational ${\cal G} = \nabla_Z Z$ and vorticity $\omega = rot Z/2$ fields (plus eventually the torsion) is provided. (3) Newtonian: Galilean structure with $\h$ flat and a field of observers Z which is inertial (its flow preserves the Leibnizian structure and $\omega = 0$). Classical concepts in Newtonian theory are revisited and discussed. |
1502.02861 | Arne Grenzebach | Arne Grenzebach | Aberrational Effects for Shadows of Black Holes | 12 pages, 3 figures; Proceedings of the 524. WE-Heraeus-Seminar held
at the Physikzentrum, Bad Honnef, Germany, 17.--23.2.2013 | null | 10.1007/978-3-319-18335-0_25 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we discuss how the shadow of a Kerr black hole depends on the
motion of the observer. In particular, we derive an analytical formula for the
boundary curve of the shadow for an observer moving with given four-velocity at
given Boyer--Lindquist coordinates. We visualize the shadow for various values
of parameters.
| [
{
"created": "Tue, 10 Feb 2015 11:09:49 GMT",
"version": "v1"
}
] | 2021-04-07 | [
[
"Grenzebach",
"Arne",
""
]
] | In this paper, we discuss how the shadow of a Kerr black hole depends on the motion of the observer. In particular, we derive an analytical formula for the boundary curve of the shadow for an observer moving with given four-velocity at given Boyer--Lindquist coordinates. We visualize the shadow for various values of parameters. |
gr-qc/0702040 | Leonardo Gualtieri | L. Gualtieri, J.A. Pons, J.A. Miralles and V. Ferrari | Relativistic r-modes and shear viscosity | 8 pages, 7 figures, to appear in the Proceedings of the Albert
Einstein Century International Conference, Paris, France, July 2005 | AIP Conf.Proc.861:638-645,2006 | 10.1063/1.2399636 | null | gr-qc astro-ph | null | We derive the relativistic equations for stellar perturbations, including in
a consistent way shear viscosity in the stress-energy tensor, and we
numerically integrate our equations in the case of large viscosity. We consider
the slow rotation approximation, and we neglect the coupling between polar and
axial perturbations. In our approach, the frequency and damping time of the
emitted gravitational radiation are directly obtained. We find that,
approaching the inviscid limit from the finite viscosity case, the continuous
spectrum is regularized. Constant density stars, polytropic stars, and stars
with realistic equations of state are considered. In the case of constant
density stars and polytropic stars, our results for the viscous damping times
agree, within a factor two, with the usual estimates obtained by using the
eigenfunctions of the inviscid limit. For realistic neutron stars, our
numerical results give viscous damping times with the same dependence on mass
and radius as previously estimated, but systematically larger of about 60%.
| [
{
"created": "Wed, 7 Feb 2007 11:07:10 GMT",
"version": "v1"
}
] | 2010-11-11 | [
[
"Gualtieri",
"L.",
""
],
[
"Pons",
"J. A.",
""
],
[
"Miralles",
"J. A.",
""
],
[
"Ferrari",
"V.",
""
]
] | We derive the relativistic equations for stellar perturbations, including in a consistent way shear viscosity in the stress-energy tensor, and we numerically integrate our equations in the case of large viscosity. We consider the slow rotation approximation, and we neglect the coupling between polar and axial perturbations. In our approach, the frequency and damping time of the emitted gravitational radiation are directly obtained. We find that, approaching the inviscid limit from the finite viscosity case, the continuous spectrum is regularized. Constant density stars, polytropic stars, and stars with realistic equations of state are considered. In the case of constant density stars and polytropic stars, our results for the viscous damping times agree, within a factor two, with the usual estimates obtained by using the eigenfunctions of the inviscid limit. For realistic neutron stars, our numerical results give viscous damping times with the same dependence on mass and radius as previously estimated, but systematically larger of about 60%. |
2208.03623 | Hirotaka Takahashi | Yusuke Sakai, Yousuke Itoh, Piljong Jung, Keiko Kokeyama, Chihiro
Kozakai, Katsuko T. Nakahira, Shoichi Oshino, Yutaka Shikano, Hirotaka
Takahashi, Takashi Uchiyama, Gen Ueshima, Tatsuki Washimi, Takahiro Yamamoto,
Takaaki Yokozawa | Training Process of Unsupervised Learning Architecture for Gravity Spy
Dataset | 17 pages, 10 figures, Matches version published in Annalen der Physik | Annalen der Physik, issue 2200140 (2022) | 10.1002/andp.202200140 | JGW-P2213998 | gr-qc stat.ML | http://creativecommons.org/licenses/by/4.0/ | Transient noise appearing in the data from gravitational-wave detectors
frequently causes problems, such as instability of the detectors and
overlapping or mimicking gravitational-wave signals. Because transient noise is
considered to be associated with the environment and instrument, its
classification would help to understand its origin and improve the detector's
performance. In a previous study, an architecture for classifying transient
noise using a time-frequency 2D image (spectrogram) is proposed, which uses
unsupervised deep learning combined with variational autoencoder and invariant
information clustering. The proposed unsupervised-learning architecture is
applied to the Gravity Spy dataset, which consists of Advanced Laser
Interferometer Gravitational-Wave Observatory (Advanced LIGO) transient noises
with their associated metadata to discuss the potential for online or offline
data analysis. In this study, focused on the Gravity Spy dataset, the training
process of unsupervised-learning architecture of the previous study is examined
and reported.
| [
{
"created": "Sun, 7 Aug 2022 02:51:36 GMT",
"version": "v1"
}
] | 2022-08-11 | [
[
"Sakai",
"Yusuke",
""
],
[
"Itoh",
"Yousuke",
""
],
[
"Jung",
"Piljong",
""
],
[
"Kokeyama",
"Keiko",
""
],
[
"Kozakai",
"Chihiro",
""
],
[
"Nakahira",
"Katsuko T.",
""
],
[
"Oshino",
"Shoichi",
""
],
[
"Shikano",
"Yutaka",
""
],
[
"Takahashi",
"Hirotaka",
""
],
[
"Uchiyama",
"Takashi",
""
],
[
"Ueshima",
"Gen",
""
],
[
"Washimi",
"Tatsuki",
""
],
[
"Yamamoto",
"Takahiro",
""
],
[
"Yokozawa",
"Takaaki",
""
]
] | Transient noise appearing in the data from gravitational-wave detectors frequently causes problems, such as instability of the detectors and overlapping or mimicking gravitational-wave signals. Because transient noise is considered to be associated with the environment and instrument, its classification would help to understand its origin and improve the detector's performance. In a previous study, an architecture for classifying transient noise using a time-frequency 2D image (spectrogram) is proposed, which uses unsupervised deep learning combined with variational autoencoder and invariant information clustering. The proposed unsupervised-learning architecture is applied to the Gravity Spy dataset, which consists of Advanced Laser Interferometer Gravitational-Wave Observatory (Advanced LIGO) transient noises with their associated metadata to discuss the potential for online or offline data analysis. In this study, focused on the Gravity Spy dataset, the training process of unsupervised-learning architecture of the previous study is examined and reported. |
0907.1967 | Jan Steinhoff | Jan Steinhoff and Gerhard Sch\"afer | Canonical formulation of self-gravitating spinning-object systems | 6 pages. v2: extended version; identical to the published one. v3:
corrected misprints in (24) and (39); improved notation; added note regarding
a further reference. | Europhys.Lett.87:50004,2009 | 10.1209/0295-5075/87/50004 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Based on the Arnowitt-Deser-Misner (ADM) canonical formulation of general
relativity, a canonical formulation of gravitationally interacting classical
spinning-object systems is given to linear order in spin. The constructed
position, linear momentum and spin variables fulfill standard Poisson bracket
relations. A spatially symmetric time gauge for the tetrad field is introduced.
The achieved formulation is of fully reduced form without unresolved
constraints, supplementary, gauge, or coordinate conditions. The canonical
field momentum is not related to the extrinsic curvature of spacelike
hypersurfaces in standard ADM form. A new reduction of the tetrad degrees of
freedom to the Einstein form of the metric field is suggested.
| [
{
"created": "Sat, 11 Jul 2009 23:33:37 GMT",
"version": "v1"
},
{
"created": "Wed, 7 Oct 2009 14:41:19 GMT",
"version": "v2"
},
{
"created": "Mon, 19 Apr 2010 12:41:47 GMT",
"version": "v3"
}
] | 2010-04-21 | [
[
"Steinhoff",
"Jan",
""
],
[
"Schäfer",
"Gerhard",
""
]
] | Based on the Arnowitt-Deser-Misner (ADM) canonical formulation of general relativity, a canonical formulation of gravitationally interacting classical spinning-object systems is given to linear order in spin. The constructed position, linear momentum and spin variables fulfill standard Poisson bracket relations. A spatially symmetric time gauge for the tetrad field is introduced. The achieved formulation is of fully reduced form without unresolved constraints, supplementary, gauge, or coordinate conditions. The canonical field momentum is not related to the extrinsic curvature of spacelike hypersurfaces in standard ADM form. A new reduction of the tetrad degrees of freedom to the Einstein form of the metric field is suggested. |
0708.4139 | Sushil Srivastava | S. K. Srivastava and J. Dutta | Non-linear Equation of State, COSMIC Acceleration and Deceleration
During Phantom-Dominance | 23 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Here, RS-II model of brane-gravity is considerd for phantom universe using
non-linear equation of stste. Phantom fluid is known to violate the weak energy
condition. In this paper, it is found that this characteristic of phantom
energy is affected drastically by the negative brane-tension $\lambda$ of the
RS-II model. It is interesting to see that upto a certain value of energy
density $\rho$ satisfying $\rho/\lambda < 1$, weak energy condition is violated
and universe super-accelerates. But as $\rho$ increases more, only strong
energy condition is violated and universe accelerates. When $1 < \rho/\lambda
<2$, even strong energy condition is not violated and universe decelerates.
Expansion of the universe stops, when $\rho = 2 \lambda$. This is contrary to
earlier results of phantom universe exhibiting acceleration only.
| [
{
"created": "Thu, 30 Aug 2007 12:22:45 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Jul 2008 12:08:40 GMT",
"version": "v2"
}
] | 2008-07-14 | [
[
"Srivastava",
"S. K.",
""
],
[
"Dutta",
"J.",
""
]
] | Here, RS-II model of brane-gravity is considerd for phantom universe using non-linear equation of stste. Phantom fluid is known to violate the weak energy condition. In this paper, it is found that this characteristic of phantom energy is affected drastically by the negative brane-tension $\lambda$ of the RS-II model. It is interesting to see that upto a certain value of energy density $\rho$ satisfying $\rho/\lambda < 1$, weak energy condition is violated and universe super-accelerates. But as $\rho$ increases more, only strong energy condition is violated and universe accelerates. When $1 < \rho/\lambda <2$, even strong energy condition is not violated and universe decelerates. Expansion of the universe stops, when $\rho = 2 \lambda$. This is contrary to earlier results of phantom universe exhibiting acceleration only. |
0711.2573 | David Burton | D.A. Burton, R.W. Tucker, C.H. Wang | Spinning particles in scalar-tensor gravity | 8 pages Corrected typo in address footnote | Phys.Lett.A372:3141-3144,2008 | 10.1016/j.physleta.2008.01.048 | null | gr-qc | null | We develop a new model of a spinning particle in Brans-Dicke spacetime using
a metric-compatible connection with torsion. The particle's spin vector is
shown to be Fermi-parallel (by the Levi-Civita connection) along its worldline
(an autoparallel of the metric-compatible connection) when neglecting
spin-curvature coupling.
| [
{
"created": "Fri, 16 Nov 2007 09:58:59 GMT",
"version": "v1"
},
{
"created": "Tue, 20 Nov 2007 15:40:53 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Burton",
"D. A.",
""
],
[
"Tucker",
"R. W.",
""
],
[
"Wang",
"C. H.",
""
]
] | We develop a new model of a spinning particle in Brans-Dicke spacetime using a metric-compatible connection with torsion. The particle's spin vector is shown to be Fermi-parallel (by the Levi-Civita connection) along its worldline (an autoparallel of the metric-compatible connection) when neglecting spin-curvature coupling. |
1601.07037 | Keith Andrew | Keith Andrew, Eric Steinfelds, Nick Zolman | The Mattig Expression for a d-dimensional Gauss Bonnet FRWL Cosmology | 15 pages | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Here we study the form of the Mattig equation applied in a cosmological
setting for spacetime metric gravity models described by the Gauss-Bonnet
action. We start with expressing the Mattig relation for cosmological
magnitudes in terms of standard metric functions and redshift values. Then we
present the Gauss-Bonnet field equations and the associated limits for special
solutions in an arbitrary number of dimensions. These solutions are used to
rewrite the Mattig relation with correction terms from the Gauss-Bonnet
contributions for the case where the Gauss-Bonnet scale factor can be directly
used to find the distance modulus and for the case where the Gauss-Bonnet field
equations can be expressed as a small high z perturbation on the standard
Einstein field equations. As a result we can express the perturbative distance
modulus, which includes the apparent magnitude, as an additive correction to
the standard distance modulus. This results in a small shift in the apparent
magnitude of a high z object which gives a contribution depending on the
Gauss-Bonnet coupling, spacetime dimension and the cosmological constant.
| [
{
"created": "Sat, 23 Jan 2016 02:04:24 GMT",
"version": "v1"
}
] | 2016-01-27 | [
[
"Andrew",
"Keith",
""
],
[
"Steinfelds",
"Eric",
""
],
[
"Zolman",
"Nick",
""
]
] | Here we study the form of the Mattig equation applied in a cosmological setting for spacetime metric gravity models described by the Gauss-Bonnet action. We start with expressing the Mattig relation for cosmological magnitudes in terms of standard metric functions and redshift values. Then we present the Gauss-Bonnet field equations and the associated limits for special solutions in an arbitrary number of dimensions. These solutions are used to rewrite the Mattig relation with correction terms from the Gauss-Bonnet contributions for the case where the Gauss-Bonnet scale factor can be directly used to find the distance modulus and for the case where the Gauss-Bonnet field equations can be expressed as a small high z perturbation on the standard Einstein field equations. As a result we can express the perturbative distance modulus, which includes the apparent magnitude, as an additive correction to the standard distance modulus. This results in a small shift in the apparent magnitude of a high z object which gives a contribution depending on the Gauss-Bonnet coupling, spacetime dimension and the cosmological constant. |
gr-qc/0609026 | Tarun Souradeep | Tarun Souradeep (IUCAA) | Spectroscopy of Cosmic topology | 8 pages, 3 figures; Invited contribution to a special issue of IJP in
memory of Prof. A.K. Raychaudhuri | Indian J.Phys. 80 (2006) 1063-1069 | null | IUCAA-43/06 | gr-qc astro-ph hep-th | null | Einstein's theory of gravitation that governs the geometry of space-time,
coupled with spectacular advance in cosmological observations, promises to
deliver a `standard model' of cosmology in the near future. However, local
geometry of space constrains, but does not dictate the topology of the cosmos.
hence, Cosmic topology has remained an enigmatic aspect of the `standard model'
of cosmology. Recent advance in the quantity and quality of observations has
brought this issue within the realm of observational query. The breakdown of
statistical homogeneity and isotropy of cosmic perturbations is a generic
consequence of non trivial cosmic topology arising from to the imposed
`crystallographic' periodicity on the eigenstates of the Laplacian. The sky
maps of Cosmic Microwave Background (CMB) anisotropy and polarization most
promising observations that would carry signatures of a violation of
statistical isotropy and homogeneity. Hence, a measurable spectroscopy of
cosmic topology is made possible using the Bipolar power spectrum (BiPS) of the
temperature and polarization that quantifies violation of statistical isotropy.
| [
{
"created": "Thu, 7 Sep 2006 12:23:45 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Souradeep",
"Tarun",
"",
"IUCAA"
]
] | Einstein's theory of gravitation that governs the geometry of space-time, coupled with spectacular advance in cosmological observations, promises to deliver a `standard model' of cosmology in the near future. However, local geometry of space constrains, but does not dictate the topology of the cosmos. hence, Cosmic topology has remained an enigmatic aspect of the `standard model' of cosmology. Recent advance in the quantity and quality of observations has brought this issue within the realm of observational query. The breakdown of statistical homogeneity and isotropy of cosmic perturbations is a generic consequence of non trivial cosmic topology arising from to the imposed `crystallographic' periodicity on the eigenstates of the Laplacian. The sky maps of Cosmic Microwave Background (CMB) anisotropy and polarization most promising observations that would carry signatures of a violation of statistical isotropy and homogeneity. Hence, a measurable spectroscopy of cosmic topology is made possible using the Bipolar power spectrum (BiPS) of the temperature and polarization that quantifies violation of statistical isotropy. |
gr-qc/0606086 | M Blagojevic | M. Blagojevic and B. Cvetkovic | Black hole entropy from the boundary conformal structure in 3D gravity
with torsion | LaTeX, 12 pages; v2: one appendix added, typos corrected, minor
changes of the text | JHEP 0610 (2006) 005 | 10.1088/1126-6708/2006/10/005 | null | gr-qc hep-th | null | Asymptotic symmetry of the Euclidean 3D gravity with torsion is described by
two independent Virasoro algebras with different central charges. Elements of
this boundary conformal structure are combined with Cardy's formula to
calculate the black hole entropy.
| [
{
"created": "Tue, 20 Jun 2006 15:39:14 GMT",
"version": "v1"
},
{
"created": "Fri, 29 Sep 2006 09:25:57 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Blagojevic",
"M.",
""
],
[
"Cvetkovic",
"B.",
""
]
] | Asymptotic symmetry of the Euclidean 3D gravity with torsion is described by two independent Virasoro algebras with different central charges. Elements of this boundary conformal structure are combined with Cardy's formula to calculate the black hole entropy. |
2112.04647 | Alexander Simpson | Alex Simpson and Matt Visser | Astrophysically viable Kerr-like spacetime -- into the eye of the storm | V1: 5 pages, 18 references | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyse a rotating regular black hole with asymptotically Minkowski core.
This Kerr-like geometry possesses the full "Killing tower" of nontrivial
Killing tensor, Killing-Yano tensor, and principal tensor. The Hamilton-Jacobi
equation, the Klein-Gordon equation, and Maxwell's equations are separable.
Energy-condition-violating physics is pushed into an arbitrarily small region
in the deep core. The geometry has a very high level of mathematical
tractability; extraction of astrophysical observables falsifiable/verifiable by
the observational community is straightforward.
| [
{
"created": "Thu, 9 Dec 2021 01:31:45 GMT",
"version": "v1"
}
] | 2021-12-10 | [
[
"Simpson",
"Alex",
""
],
[
"Visser",
"Matt",
""
]
] | We analyse a rotating regular black hole with asymptotically Minkowski core. This Kerr-like geometry possesses the full "Killing tower" of nontrivial Killing tensor, Killing-Yano tensor, and principal tensor. The Hamilton-Jacobi equation, the Klein-Gordon equation, and Maxwell's equations are separable. Energy-condition-violating physics is pushed into an arbitrarily small region in the deep core. The geometry has a very high level of mathematical tractability; extraction of astrophysical observables falsifiable/verifiable by the observational community is straightforward. |
1805.04447 | Julia Tchemarina | P V Kratovitch, I M Potashov, Ju V Tchemarina and A N Tsirulev | Topological geons with self-gravitating phantom scalar field | 5 pages, presented at the 3rd International Conference on Particle
Physics and Astrophysics (ICPPA 2017) | IOP Conf. Series: Journal of Physics: Conf. Series 934 (2017)
012047 | 10.1088/1742-6596/934/1/012047 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A topological geon is the quotient manifold $M/Z_2$ where $M$ is a static
spherically symmetric wormhole having the reflection symmetry with respect to
its throat. We distinguish such asymptotically flat solutions of the Einstein
equations according to the form of the time-time metric function by using the
quadrature formulas of the so-called inverse problem for self-gravitating
spherically symmetric scalar fields. We distinguish three types of geon
spacetimes and illustrate them by simple examples. We also study possible
observational effects associated with bounded geodesic motion near topological
geons.
| [
{
"created": "Fri, 11 May 2018 15:27:16 GMT",
"version": "v1"
}
] | 2018-05-14 | [
[
"Kratovitch",
"P V",
""
],
[
"Potashov",
"I M",
""
],
[
"Tchemarina",
"Ju V",
""
],
[
"Tsirulev",
"A N",
""
]
] | A topological geon is the quotient manifold $M/Z_2$ where $M$ is a static spherically symmetric wormhole having the reflection symmetry with respect to its throat. We distinguish such asymptotically flat solutions of the Einstein equations according to the form of the time-time metric function by using the quadrature formulas of the so-called inverse problem for self-gravitating spherically symmetric scalar fields. We distinguish three types of geon spacetimes and illustrate them by simple examples. We also study possible observational effects associated with bounded geodesic motion near topological geons. |
1002.3588 | Mubasher Jamil | H. Mohseni Sadjadi and Mubasher Jamil | Generalized second law of thermodynamics for FRW cosmology with
logarithmic correction | 14 pages, accepted for publication in Europhysics Letters | EPL, 92 (2010) 69001 | 10.1209/0295-5075/92/69001 | arXiv:1002.3588v2 [gr-qc] | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the previous analyses in the literature about the generalized second law
(GSL) in an accelerated expanding universe the usual area relation for the
entropy, i.e. $S={A\over 4G}$, was used for the cosmological horizon entropy.
But this entropy relation may be modified due to thermal and quantum
fluctuations or corrections motivated by loop quantum gravity giving rise to
S={A\over 4}+\pi\alpha \ln({A\over 4})+\gamma, where $\alpha$ and $\gamma$ are
some constants whose the values are still in debate in the literature. Our aim
is to study the constraints that GSL puts on these parameters. Besides, we
investigate the conditions that the presence of such modified terms in the
entropy puts on other physical parameters the system such as the temperature of
dark energy via requiring the validity of GSL. In our study we consider a
spatially flat Friedman-Robertson-Walker and assume that the universe is
composed of several interacting components (including dark energy). The model
is investigated in the context of thermal equilibrium and non-equilibrium
situations. We show that in a (super) accelerated universe GSL is valid
whenever $\alpha (<)>0$ leading to a (negative) positive contribution from
logarithmic correction to the entropy. In the case of super acceleration the
temperature of the dark energy is obtained to be less or equal to the Hawking
temperature.
| [
{
"created": "Thu, 18 Feb 2010 18:12:26 GMT",
"version": "v1"
},
{
"created": "Wed, 1 Dec 2010 04:18:34 GMT",
"version": "v2"
}
] | 2011-01-14 | [
[
"Sadjadi",
"H. Mohseni",
""
],
[
"Jamil",
"Mubasher",
""
]
] | In the previous analyses in the literature about the generalized second law (GSL) in an accelerated expanding universe the usual area relation for the entropy, i.e. $S={A\over 4G}$, was used for the cosmological horizon entropy. But this entropy relation may be modified due to thermal and quantum fluctuations or corrections motivated by loop quantum gravity giving rise to S={A\over 4}+\pi\alpha \ln({A\over 4})+\gamma, where $\alpha$ and $\gamma$ are some constants whose the values are still in debate in the literature. Our aim is to study the constraints that GSL puts on these parameters. Besides, we investigate the conditions that the presence of such modified terms in the entropy puts on other physical parameters the system such as the temperature of dark energy via requiring the validity of GSL. In our study we consider a spatially flat Friedman-Robertson-Walker and assume that the universe is composed of several interacting components (including dark energy). The model is investigated in the context of thermal equilibrium and non-equilibrium situations. We show that in a (super) accelerated universe GSL is valid whenever $\alpha (<)>0$ leading to a (negative) positive contribution from logarithmic correction to the entropy. In the case of super acceleration the temperature of the dark energy is obtained to be less or equal to the Hawking temperature. |
gr-qc/0312028 | Monica Varvella | M. Arnaud-Varvella, M.-C. Angonin, Ph. Tourrenc | Increase of the Number of Detectable Gravitational Waves Signals due to
Gravitational Lensing | Accepted for publication in General Relativity and Gravitation | Gen.Rel.Grav. 36 (2004) 983-999 | 10.1023/B:GERG.0000018085.46454.ff | null | gr-qc astro-ph | null | This article deals with the gravitational lensing (GL) of gravitational waves
(GW). We compute the increase in the number of detected GW events due to GL.
First, we check that geometrical optics is valid for the GW frequency range on
which Earth-based detectors are sensitive, and that this is also partially true
for what concerns the future space-based interferometer LISA. To infer this
result, both the diffraction parameter and a cut-off frequency are computed.
Then, the variation in the number of GW signals is estimated in the general
case, and applied to some lens models: point mass lens and singular isothermal
sphere (SIS profile). An estimation of the magnification factor has also been
done for the softened isothermal sphere and for the King profile. The results
appear to be strongly model-dependent, but in all cases the increase in the
number of detected GW signals is negligible. The use of time delays among
images is also investigated.
| [
{
"created": "Thu, 4 Dec 2003 12:38:15 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Arnaud-Varvella",
"M.",
""
],
[
"Angonin",
"M. -C.",
""
],
[
"Tourrenc",
"Ph.",
""
]
] | This article deals with the gravitational lensing (GL) of gravitational waves (GW). We compute the increase in the number of detected GW events due to GL. First, we check that geometrical optics is valid for the GW frequency range on which Earth-based detectors are sensitive, and that this is also partially true for what concerns the future space-based interferometer LISA. To infer this result, both the diffraction parameter and a cut-off frequency are computed. Then, the variation in the number of GW signals is estimated in the general case, and applied to some lens models: point mass lens and singular isothermal sphere (SIS profile). An estimation of the magnification factor has also been done for the softened isothermal sphere and for the King profile. The results appear to be strongly model-dependent, but in all cases the increase in the number of detected GW signals is negligible. The use of time delays among images is also investigated. |
1112.2785 | Li-Fang Li | Li-Fang Li, Rong-Gen Cai, Zong-Kuan Guo, and Bin Hu | Non-Gaussian features from the inverse volume corrections in loop
quantum cosmology | matched to the published version. 30 pages, 4 figures | Phys. Rev. D 86, 044020 (2012) | 10.1103/PhysRevD.86.044020 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we study the non-Gaussian features of the primordial
fluctuations in loop quantum cosmology with the inverse volume corrections. The
detailed analysis is performed in the single field slow-roll inflationary
models. However, our results reflect the universal characteristics of
bispectrum in loop quantum cosmology. The main corrections to the scalar
bispectrum come from two aspects: one is the modifications to the standard
Bunch-Davies vacuum, the other is the corrections to the background dependent
variables, such as slow-roll parameters. Our calculations show that the loop
quantum corrections make $f_{{\rm NL}}$ of the inflationary models increase
0.1%. Moreover, we find that two new shapes arise, namely $\mathcal F_{1}$ and
$\mathcal F_{2}$. The former gives a unique loop quantum feature which is less
correlated with the local, equilateral and single types, while the latter is
highly correlated with the local one.
| [
{
"created": "Tue, 13 Dec 2011 03:36:15 GMT",
"version": "v1"
},
{
"created": "Sun, 23 Sep 2012 11:08:45 GMT",
"version": "v2"
}
] | 2012-09-25 | [
[
"Li",
"Li-Fang",
""
],
[
"Cai",
"Rong-Gen",
""
],
[
"Guo",
"Zong-Kuan",
""
],
[
"Hu",
"Bin",
""
]
] | In this paper we study the non-Gaussian features of the primordial fluctuations in loop quantum cosmology with the inverse volume corrections. The detailed analysis is performed in the single field slow-roll inflationary models. However, our results reflect the universal characteristics of bispectrum in loop quantum cosmology. The main corrections to the scalar bispectrum come from two aspects: one is the modifications to the standard Bunch-Davies vacuum, the other is the corrections to the background dependent variables, such as slow-roll parameters. Our calculations show that the loop quantum corrections make $f_{{\rm NL}}$ of the inflationary models increase 0.1%. Moreover, we find that two new shapes arise, namely $\mathcal F_{1}$ and $\mathcal F_{2}$. The former gives a unique loop quantum feature which is less correlated with the local, equilateral and single types, while the latter is highly correlated with the local one. |
0901.0978 | T. P. Singh | T. P. Singh | Quantum theory, noncommutative gravity, and the cosmological constant
problem | 10 pages. One paragraph each added at the end of Section 4 and
Section 7. Version matches published version | Advances in Astronomy 2009 (2009) 632064 | 10.1155/2009/632064 | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The cosmological constant problem is principally concerned with trying to
understand how the zero-point energy of quantum fields contributes to gravity.
Here we take the approach that by addressing a fundamental unresolved issue in
quantum theory we can gain a better understanding of the problem. Our starting
point is the observation that the notion of classical time is external to
quantum mechanics. Hence there must exist an equivalent reformulation of
quantum mechanics which does not refer to an external classical time. Such a
reformulation is a limiting case of a more general quantum theory which becomes
nonlinear on the Planck mass/energy scale. The nonlinearity gives rise to a
quantum-classical duality which maps a `strongly quantum, weakly gravitational'
dynamics to a `weakly quantum, strongly gravitational' dynamics. This duality
predicts the existence of a tiny nonzero cosmological constant of the order of
the square of the Hubble constant, which could be a possible source for the
observed cosmic acceleration. Such a nonlinearity could also be responsible for
the collapse of the wave-function during a quantum measurement. We conclude by
suggesting that the idea for the origin of dark energy proposed in this paper
can be tested indirectly in the laboratory by a detailed examination of the
process of quantum measurement.
| [
{
"created": "Thu, 8 Jan 2009 06:28:52 GMT",
"version": "v1"
},
{
"created": "Mon, 30 Nov 2009 16:30:18 GMT",
"version": "v2"
}
] | 2009-11-30 | [
[
"Singh",
"T. P.",
""
]
] | The cosmological constant problem is principally concerned with trying to understand how the zero-point energy of quantum fields contributes to gravity. Here we take the approach that by addressing a fundamental unresolved issue in quantum theory we can gain a better understanding of the problem. Our starting point is the observation that the notion of classical time is external to quantum mechanics. Hence there must exist an equivalent reformulation of quantum mechanics which does not refer to an external classical time. Such a reformulation is a limiting case of a more general quantum theory which becomes nonlinear on the Planck mass/energy scale. The nonlinearity gives rise to a quantum-classical duality which maps a `strongly quantum, weakly gravitational' dynamics to a `weakly quantum, strongly gravitational' dynamics. This duality predicts the existence of a tiny nonzero cosmological constant of the order of the square of the Hubble constant, which could be a possible source for the observed cosmic acceleration. Such a nonlinearity could also be responsible for the collapse of the wave-function during a quantum measurement. We conclude by suggesting that the idea for the origin of dark energy proposed in this paper can be tested indirectly in the laboratory by a detailed examination of the process of quantum measurement. |
1708.04003 | Ken-Ichi Nakao | Ken-ichi Nakao, Hirotada Okawa and Kei-ichi Maeda | Non-linear collisional Penrose process: How large energy can a black
hole release? | 24 pages, 3 figures | null | null | OCU-PHYS-469, AP-GR-141 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Energy extraction from a rotating or charged black hole is one of fascinating
issues in general relativity. The collisional Penrose process is one of such
extraction mechanisms and has been reconsidered intensively since Banados, Silk
and West pointed out the physical importance of very high energy collisions
around a maximally rotating black hole. In order to get results analytically,
the test particle approximation has been adopted so far. Successive works based
on this approximation scheme have not yet revealed the upper bound on the
efficiency of the energy extraction because of lack of the back reaction. In
the Reissner-Nordstrom spacetime, by fully taking into account the self-gravity
of the shells, we find that there is an upper bound on the extracted energy,
which is consistent with the area law of a black hole. We also show one
particular scenario in which the almost maximum energy extraction is achieved
even without the Banados-Silk-West collision.
| [
{
"created": "Mon, 14 Aug 2017 04:13:44 GMT",
"version": "v1"
}
] | 2017-08-15 | [
[
"Nakao",
"Ken-ichi",
""
],
[
"Okawa",
"Hirotada",
""
],
[
"Maeda",
"Kei-ichi",
""
]
] | Energy extraction from a rotating or charged black hole is one of fascinating issues in general relativity. The collisional Penrose process is one of such extraction mechanisms and has been reconsidered intensively since Banados, Silk and West pointed out the physical importance of very high energy collisions around a maximally rotating black hole. In order to get results analytically, the test particle approximation has been adopted so far. Successive works based on this approximation scheme have not yet revealed the upper bound on the efficiency of the energy extraction because of lack of the back reaction. In the Reissner-Nordstrom spacetime, by fully taking into account the self-gravity of the shells, we find that there is an upper bound on the extracted energy, which is consistent with the area law of a black hole. We also show one particular scenario in which the almost maximum energy extraction is achieved even without the Banados-Silk-West collision. |
2110.01814 | Matt Visser | Joshua Baines, Thomas Berry, Alex Simpson, and Matt Visser | Killing tensor and Carter constant for Painleve-Gullstrand form of
Lense-Thirring spacetime | V1: 17 pages, no figures; V2: some added comments/clarifications, 1
added reference, no physics changes | Universe 7 (2021) 473 | 10.3390/universe7120473 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, the authors have formulated and explored a novel
Painleve-Gullstrand variant of the Lense-Thirring spacetime, which has some
particularly elegant features -- including unit-lapse, intrinsically flat
spatial 3-slices, and some particularly simple geodesics, the "rain" geodesics.
At linear level in the rotation parameter this spacetime is indistinguishable
from the usual slow-rotation expansion of Kerr. Herein, we shall show that this
spacetime possesses a nontrivial Killing tensor, implying separability of the
Hamilton-Jacobi equation. Furthermore, we shall show that the Klein-Gordon
equation is also separable on this spacetime. However, while the Killing tensor
has a 2-form square root, we shall see that this 2-form square root of the
Killing tensor is not a Killing-Yano tensor. Finally, the
Killing-tensor-induced Carter constant is easily extracted, and now, with a
fourth constant of motion, the geodesics become (in principle) explicitly
integrable.
| [
{
"created": "Tue, 5 Oct 2021 04:23:14 GMT",
"version": "v1"
},
{
"created": "Mon, 18 Oct 2021 05:41:36 GMT",
"version": "v2"
}
] | 2022-01-05 | [
[
"Baines",
"Joshua",
""
],
[
"Berry",
"Thomas",
""
],
[
"Simpson",
"Alex",
""
],
[
"Visser",
"Matt",
""
]
] | Recently, the authors have formulated and explored a novel Painleve-Gullstrand variant of the Lense-Thirring spacetime, which has some particularly elegant features -- including unit-lapse, intrinsically flat spatial 3-slices, and some particularly simple geodesics, the "rain" geodesics. At linear level in the rotation parameter this spacetime is indistinguishable from the usual slow-rotation expansion of Kerr. Herein, we shall show that this spacetime possesses a nontrivial Killing tensor, implying separability of the Hamilton-Jacobi equation. Furthermore, we shall show that the Klein-Gordon equation is also separable on this spacetime. However, while the Killing tensor has a 2-form square root, we shall see that this 2-form square root of the Killing tensor is not a Killing-Yano tensor. Finally, the Killing-tensor-induced Carter constant is easily extracted, and now, with a fourth constant of motion, the geodesics become (in principle) explicitly integrable. |
gr-qc/9909041 | Janna Levin | Janna Levin and John D. Barrow | Fractals and Scars on a Compact Octagon | 6 pages, 3 figs, LaTeX file | Class.Quant.Grav.17:L61-L68,2000 | 10.1088/0264-9381/17/6/101 | null | gr-qc astro-ph chao-dyn nlin.CD | null | A finite universe naturally supports chaotic classical motion. An ordered
fractal emerges from the chaotic dynamics which we characterize in full for a
compact 2-dimensional octagon. In the classical to quantum transition, the
underlying fractal can persist in the form of scars, ridges of enhanced
amplitude in the semiclassical wave function. Although the scarring is weak on
the octagon, we suggest possible subtle implications of fractals and scars in a
finite universe.
| [
{
"created": "Tue, 14 Sep 1999 12:30:57 GMT",
"version": "v1"
}
] | 2010-04-06 | [
[
"Levin",
"Janna",
""
],
[
"Barrow",
"John D.",
""
]
] | A finite universe naturally supports chaotic classical motion. An ordered fractal emerges from the chaotic dynamics which we characterize in full for a compact 2-dimensional octagon. In the classical to quantum transition, the underlying fractal can persist in the form of scars, ridges of enhanced amplitude in the semiclassical wave function. Although the scarring is weak on the octagon, we suggest possible subtle implications of fractals and scars in a finite universe. |
0908.0444 | Mubasher Jamil | Mubasher Jamil and Asghar Qadir | Primordial Black Holes in Phantom Cosmology | 17 pages, 10 figures, accepted for publication in Gen. Relativ.
Gravit | Gen.Rel.Grav.43:1069-1082,2011 | 10.1007/s10714-010-0928-1 | arXiv:0908.0444v3 [gr-qc] | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the effects of accretion of phantom energy onto primordial
black holes. Since Hawking radiation and phantom energy accretion contribute to
a {\it decrease} of the mass of the black hole, the primordial black hole that
would be expected to decay now due to the Hawking process would decay {\it
earlier} due to the inclusion of the phantom energy. Equivalently, to have the
primordial black hole decay now it would have to be more massive initially. We
find that the effect of the phantom energy is substantial and the black holes
decaying now would be {\it much} more massive -- over 10 orders of magnitude!
This effect will be relevant for determining the time of production and hence
the number of evaporating black holes expected in a universe accelerating due
to phantom energy.
| [
{
"created": "Tue, 4 Aug 2009 13:39:21 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Aug 2009 18:09:09 GMT",
"version": "v2"
},
{
"created": "Thu, 17 Dec 2009 05:03:21 GMT",
"version": "v3"
}
] | 2011-03-28 | [
[
"Jamil",
"Mubasher",
""
],
[
"Qadir",
"Asghar",
""
]
] | We investigate the effects of accretion of phantom energy onto primordial black holes. Since Hawking radiation and phantom energy accretion contribute to a {\it decrease} of the mass of the black hole, the primordial black hole that would be expected to decay now due to the Hawking process would decay {\it earlier} due to the inclusion of the phantom energy. Equivalently, to have the primordial black hole decay now it would have to be more massive initially. We find that the effect of the phantom energy is substantial and the black holes decaying now would be {\it much} more massive -- over 10 orders of magnitude! This effect will be relevant for determining the time of production and hence the number of evaporating black holes expected in a universe accelerating due to phantom energy. |
2401.13374 | Vittorio De Falco Dr | Vittorio De Falco, Emmanuele Battista, Davide Usseglio, Salvatore
Capozziello | Radiative losses and radiation-reaction effects at the first
post-Newtonian order in Einstein-Cartan theory | 19 pages, 3 figures, 1 table; accepted for publication on EPJ C | null | 10.1140/epjc/s10052-024-12476-4 | null | gr-qc astro-ph.HE hep-th math-ph math.MP | http://creativecommons.org/licenses/by/4.0/ | Gravitational radiation-reaction phenomena occurring in the dynamics of
inspiralling compact binary systems are investigated at the first
post-Newtonian order beyond the quadrupole approximation in the context of
Einstein-Cartan theory, where quantum spin effects are modeled via the
Weyssenhoff fluid. We exploit balance equations for the energy and angular
momentum to determine the binary orbital decay until the two bodies collide.
Our framework deals with both quasi-elliptic and quasi-circular trajectories,
which are then smoothly connected. Key observables like the laws of variation
of the orbital phase and frequency characterizing the quasi-circular motion are
derived analytically. We conclude our analysis with an estimation of the spin
contributions at the merger, which are examined both in the time domain and the
Fourier frequency space through the stationary wave approximation.
| [
{
"created": "Wed, 24 Jan 2024 11:08:01 GMT",
"version": "v1"
}
] | 2024-02-09 | [
[
"De Falco",
"Vittorio",
""
],
[
"Battista",
"Emmanuele",
""
],
[
"Usseglio",
"Davide",
""
],
[
"Capozziello",
"Salvatore",
""
]
] | Gravitational radiation-reaction phenomena occurring in the dynamics of inspiralling compact binary systems are investigated at the first post-Newtonian order beyond the quadrupole approximation in the context of Einstein-Cartan theory, where quantum spin effects are modeled via the Weyssenhoff fluid. We exploit balance equations for the energy and angular momentum to determine the binary orbital decay until the two bodies collide. Our framework deals with both quasi-elliptic and quasi-circular trajectories, which are then smoothly connected. Key observables like the laws of variation of the orbital phase and frequency characterizing the quasi-circular motion are derived analytically. We conclude our analysis with an estimation of the spin contributions at the merger, which are examined both in the time domain and the Fourier frequency space through the stationary wave approximation. |
2004.07613 | Ivan Kolar | Ivan Kolar, Anupam Mazumdar | NUT charge in linearized infinite derivative gravity | 10 pages, 4 figures | Phys. Rev. D 101, 124005 (2020) | 10.1103/PhysRevD.101.124005 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the gravitational field of the NUT-like source in the linearized
(ghost-free) infinite derivative gravity. Such a source is equivalent to the
spinning semi-infinite cosmic string with no tension. In general relativity,
the linearized (massless) Taub-NUT solution has a curvature singularity as well
as a topological defect corresponding to distributional curvature on one half
of the symmetry axis called the Misner string. We find the NUT-charged
spacetime in the linearized infinite derivative gravity. We show that it is
free from curvature singularities as well as Misner strings. We also discuss an
asymptotic limit along the symmetry axis that leads to the spacetime of a
spinning cosmic string of infinite length.
| [
{
"created": "Thu, 16 Apr 2020 11:50:02 GMT",
"version": "v1"
},
{
"created": "Wed, 22 Apr 2020 15:35:37 GMT",
"version": "v2"
},
{
"created": "Fri, 29 May 2020 08:37:53 GMT",
"version": "v3"
}
] | 2020-06-04 | [
[
"Kolar",
"Ivan",
""
],
[
"Mazumdar",
"Anupam",
""
]
] | We study the gravitational field of the NUT-like source in the linearized (ghost-free) infinite derivative gravity. Such a source is equivalent to the spinning semi-infinite cosmic string with no tension. In general relativity, the linearized (massless) Taub-NUT solution has a curvature singularity as well as a topological defect corresponding to distributional curvature on one half of the symmetry axis called the Misner string. We find the NUT-charged spacetime in the linearized infinite derivative gravity. We show that it is free from curvature singularities as well as Misner strings. We also discuss an asymptotic limit along the symmetry axis that leads to the spacetime of a spinning cosmic string of infinite length. |
1509.07021 | Lorenzo Sebastiani | Shynaray Myrzakul, Ratbay Myrzakulov and Lorenzo Sebastiani | $f(\phi) R$-models for inflation | 9 pages, revised version, accepted in IJMPD | null | 10.1142/S0218271816500413 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we investigate models where a scalar field driving inflation
is minimally coupled with gravity and it is subjected to a scalar potential. We
present several examples of coupling between the field and gravity, and we
furnish realistic models for inflation in agreement with the last Planck
results.
| [
{
"created": "Tue, 22 Sep 2015 12:02:25 GMT",
"version": "v1"
},
{
"created": "Sun, 13 Dec 2015 12:16:46 GMT",
"version": "v2"
}
] | 2016-03-01 | [
[
"Myrzakul",
"Shynaray",
""
],
[
"Myrzakulov",
"Ratbay",
""
],
[
"Sebastiani",
"Lorenzo",
""
]
] | In this paper, we investigate models where a scalar field driving inflation is minimally coupled with gravity and it is subjected to a scalar potential. We present several examples of coupling between the field and gravity, and we furnish realistic models for inflation in agreement with the last Planck results. |
2310.03811 | Costantino Pacilio | Costantino Pacilio, Davide Gerosa, Swetha Bhagwat | Catalog variance of testing general relativity with gravitational-wave
data | 6 pages, 2 figures; v2: matches published version | Physical Review D 109.8, L081302 (2024) | 10.1103/PhysRevD.109.L081302 | null | gr-qc astro-ph.HE hep-ph physics.data-an | http://creativecommons.org/licenses/by/4.0/ | Combining multiple gravitational-wave observations allows for stringent tests
of general relativity, targeting effects that would otherwise be undetectable
using single-event analyses. We highlight how the finite size of the observed
catalog induces a significant source of variance. If not appropriately
accounted for, general relativity can be excluded with arbitrarily large
credibility even if it is the underlying theory of gravity. This effect is
generic and holds for arbitrarily large catalogs. Moreover, we show that it
cannot be suppressed by selecting "golden" observations with large
signal-to-noise ratios. We present a mitigation strategy based on bootstrapping
(i.e. resampling with repetition) that allows assigning uncertainties to one's
credibility on the targeted test. We demonstrate our findings using both toy
models and real gravitational-wave data. In particular, we quantify the impact
of the catalog variance on the ringdown properties of black holes using the
latest LIGO/Virgo catalog.
| [
{
"created": "Thu, 5 Oct 2023 18:01:01 GMT",
"version": "v1"
},
{
"created": "Tue, 7 May 2024 10:48:52 GMT",
"version": "v2"
}
] | 2024-05-08 | [
[
"Pacilio",
"Costantino",
""
],
[
"Gerosa",
"Davide",
""
],
[
"Bhagwat",
"Swetha",
""
]
] | Combining multiple gravitational-wave observations allows for stringent tests of general relativity, targeting effects that would otherwise be undetectable using single-event analyses. We highlight how the finite size of the observed catalog induces a significant source of variance. If not appropriately accounted for, general relativity can be excluded with arbitrarily large credibility even if it is the underlying theory of gravity. This effect is generic and holds for arbitrarily large catalogs. Moreover, we show that it cannot be suppressed by selecting "golden" observations with large signal-to-noise ratios. We present a mitigation strategy based on bootstrapping (i.e. resampling with repetition) that allows assigning uncertainties to one's credibility on the targeted test. We demonstrate our findings using both toy models and real gravitational-wave data. In particular, we quantify the impact of the catalog variance on the ringdown properties of black holes using the latest LIGO/Virgo catalog. |
gr-qc/9710100 | Frank Antonsen | Frank Antonsen | The Heat-Kernel in a Schwarzschild Geometry and the Casimir Energy | LaTeX2e (minor errors corrected, discussion extended and a few new
results added) | null | null | null | gr-qc hep-th quant-ph | null | We obtain an hybrid expression for the heat-kernel, and from that the density
of the free energy, for a minimally coupled scalar field in a Schwarzschild
geometry at finite temperature. This gives us the zero-point energy density as
a function of the distance from the massive object generating the gravitational
field. The contribution to the zero-point energy due to the curvature is
extracted too, in this way arriving at a renormalised expression for the energy
density (the Casimir energy density). We use this to find an expression for
other physical quantities: internal energy, pressure and entropy. It turns out
that the disturbance of the surrounding vacuum generates entropy. For $\beta$
small the entropy is positive for $r>2M$. We also find that the internal energy
can be negative outside the horizon pointing to the existence of bound states.
The total energy inside the horizon turns out to be finite but complex, the
imaginary part being interpreted as responsible for particle creation.
| [
{
"created": "Tue, 21 Oct 1997 14:00:39 GMT",
"version": "v1"
},
{
"created": "Mon, 19 Jan 1998 11:45:23 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Antonsen",
"Frank",
""
]
] | We obtain an hybrid expression for the heat-kernel, and from that the density of the free energy, for a minimally coupled scalar field in a Schwarzschild geometry at finite temperature. This gives us the zero-point energy density as a function of the distance from the massive object generating the gravitational field. The contribution to the zero-point energy due to the curvature is extracted too, in this way arriving at a renormalised expression for the energy density (the Casimir energy density). We use this to find an expression for other physical quantities: internal energy, pressure and entropy. It turns out that the disturbance of the surrounding vacuum generates entropy. For $\beta$ small the entropy is positive for $r>2M$. We also find that the internal energy can be negative outside the horizon pointing to the existence of bound states. The total energy inside the horizon turns out to be finite but complex, the imaginary part being interpreted as responsible for particle creation. |
1612.00760 | Suddhasattwa Brahma | Pietro Dona and Antonino Marciano | Non Bunch Davies group coherent states, and their quantum signatures in
CMB observables | 17 pages | null | null | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We approach the problem of finding generalized states for matter fields in a
de Sitter universe, moving from a group theoretical point of view. This has
profound consequences for cosmological perturbations during inflation, and for
other CMB observables. In a systematic derivation, we find all the allowed
generalities that such a state may have, within the requirements of coherent
states. Furthermore, we show their relation to the more familiar excited
initial states, often used in inflation.
| [
{
"created": "Fri, 2 Dec 2016 17:21:36 GMT",
"version": "v1"
},
{
"created": "Wed, 26 Apr 2017 10:16:29 GMT",
"version": "v2"
},
{
"created": "Fri, 3 Jul 2020 01:08:56 GMT",
"version": "v3"
}
] | 2020-07-06 | [
[
"Dona",
"Pietro",
""
],
[
"Marciano",
"Antonino",
""
]
] | We approach the problem of finding generalized states for matter fields in a de Sitter universe, moving from a group theoretical point of view. This has profound consequences for cosmological perturbations during inflation, and for other CMB observables. In a systematic derivation, we find all the allowed generalities that such a state may have, within the requirements of coherent states. Furthermore, we show their relation to the more familiar excited initial states, often used in inflation. |
0710.1411 | Nosrat-ollah Jafari Sonbolabadi | Ahmad Shariati, Nosratollah Jafari | MOND, dark matter, and conservation of energy | 4 pages, LaTeX | null | null | null | gr-qc astro-ph hep-th | null | The MOND equation $m \vec a \mu(a) = \vec F$ could be transformed to the
equivalent form $m \vec a = \vec{F'}$, where $\Vec{F'}$ is a transformed force.
Using this transformation we argue that MOND could not avoid introducing dark
matter, and introduces nonconservative terms to the equations of motion.
| [
{
"created": "Sun, 7 Oct 2007 11:12:31 GMT",
"version": "v1"
}
] | 2007-10-14 | [
[
"Shariati",
"Ahmad",
""
],
[
"Jafari",
"Nosratollah",
""
]
] | The MOND equation $m \vec a \mu(a) = \vec F$ could be transformed to the equivalent form $m \vec a = \vec{F'}$, where $\Vec{F'}$ is a transformed force. Using this transformation we argue that MOND could not avoid introducing dark matter, and introduces nonconservative terms to the equations of motion. |
2205.07538 | Chao Niu | Wei Xiong, Peng Liu, Chao Niu, Cheng-Yong Zhang, and Bin Wang | Dynamical spontaneous scalarization in Einstein-Maxwell-scalar theory | 17 pages, 17 figures, the version accepted by CPC | null | 10.1088/1674-1137/ac70ad | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the linear instability and the nonlinear dynamical evolution of the
Reissner-Nordstr\"om (RN) black hole in the Einstein-Maxwell-scalar theory in
asymptotic flat spacetime. We focus on the coupling function
$f(\phi)=e^{-b\phi^2}$ which allows both the scalar-free RN solution and
scalarized black hole solution. We first present the evolution of system
parameters during dynamic scalarization. For parameter regions where
spontaneous scalarization occurs, we find that the evolution of the scalar
field at the horizon is dominated by the fundamental unstable mode from linear
analysis at early times. At late times, the nonlinear evolution can be viewed
as the perturbation of scalarized black holes.
| [
{
"created": "Mon, 16 May 2022 09:34:28 GMT",
"version": "v1"
}
] | 2022-09-14 | [
[
"Xiong",
"Wei",
""
],
[
"Liu",
"Peng",
""
],
[
"Niu",
"Chao",
""
],
[
"Zhang",
"Cheng-Yong",
""
],
[
"Wang",
"Bin",
""
]
] | We study the linear instability and the nonlinear dynamical evolution of the Reissner-Nordstr\"om (RN) black hole in the Einstein-Maxwell-scalar theory in asymptotic flat spacetime. We focus on the coupling function $f(\phi)=e^{-b\phi^2}$ which allows both the scalar-free RN solution and scalarized black hole solution. We first present the evolution of system parameters during dynamic scalarization. For parameter regions where spontaneous scalarization occurs, we find that the evolution of the scalar field at the horizon is dominated by the fundamental unstable mode from linear analysis at early times. At late times, the nonlinear evolution can be viewed as the perturbation of scalarized black holes. |
gr-qc/0504134 | Stuart Reid Mr | S. Reid, G. Cagnoli, D.R.M. Crooks, J. Hough, P. Murray, S. Rowan,
M.M. Fejer, R. Route, S. Zappe | Mechanical Dissipation in Silicon Flexures | 7 pages. Accepted by Phys Lett A, submitted for publication on 28
October 2005 | eConf C041213 (2004) 1222; Phys.Lett. A351 (2006) 205-211 | 10.1016/j.physleta.2005.10.103 | null | gr-qc | null | The thermo-mechanical properties of silicon make it of significant interest
as a possible material for mirror substrates and suspension elements for future
long-baseline gravitational wave detectors. The mechanical dissipation in 92um
thick <110> single-crystal silicon cantilevers has been observed over the
temperature range 85 K to 300 K, with dissipation approaching levels down to
phi = 4.4E-7.
| [
{
"created": "Wed, 27 Apr 2005 09:09:58 GMT",
"version": "v1"
},
{
"created": "Fri, 28 Oct 2005 12:16:42 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Reid",
"S.",
""
],
[
"Cagnoli",
"G.",
""
],
[
"Crooks",
"D. R. M.",
""
],
[
"Hough",
"J.",
""
],
[
"Murray",
"P.",
""
],
[
"Rowan",
"S.",
""
],
[
"Fejer",
"M. M.",
""
],
[
"Route",
"R.",
""
],
[
"Zappe",
"S.",
""
]
] | The thermo-mechanical properties of silicon make it of significant interest as a possible material for mirror substrates and suspension elements for future long-baseline gravitational wave detectors. The mechanical dissipation in 92um thick <110> single-crystal silicon cantilevers has been observed over the temperature range 85 K to 300 K, with dissipation approaching levels down to phi = 4.4E-7. |
2312.01136 | P. Vaishak | Vaishak Prasad | The Shear at the Common Dynamical Horizon in Binary Black Hole Mergers
and its Imprint in their Gravitational Radiation | 8 pages, 3 Figures and 4 tables | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the correlation between a part of the gravitational field at the
common dynamical horizon in the strong field regime and the news of the
gravitational radiation received from the system in the weak field regime, in
the post-merger phase of quasi-circular, non-spinning binary black hole mergers
using numerical relativity simulations. We find that, as in the inspiral phase
Phys.Rev.Lett.125,121101, the shear of the common dynamical horizon formed late
into the inspiral continues to be well correlated with the news of the outgoing
gravitational radiation even at early times. We show by fitting that the shear
contains certain quasi-normal frequencies and information about the masses and
spins of the remnant and the parent black holes, providing evidence to support
the horizon correlation conjecture holds for dynamical horizons in binary black
hole mergers.
| [
{
"created": "Sat, 2 Dec 2023 13:35:10 GMT",
"version": "v1"
}
] | 2023-12-05 | [
[
"Prasad",
"Vaishak",
""
]
] | We study the correlation between a part of the gravitational field at the common dynamical horizon in the strong field regime and the news of the gravitational radiation received from the system in the weak field regime, in the post-merger phase of quasi-circular, non-spinning binary black hole mergers using numerical relativity simulations. We find that, as in the inspiral phase Phys.Rev.Lett.125,121101, the shear of the common dynamical horizon formed late into the inspiral continues to be well correlated with the news of the outgoing gravitational radiation even at early times. We show by fitting that the shear contains certain quasi-normal frequencies and information about the masses and spins of the remnant and the parent black holes, providing evidence to support the horizon correlation conjecture holds for dynamical horizons in binary black hole mergers. |
gr-qc/0002062 | Filipe Mena | Filipe C. Mena (QMW, London), Reza Tavakol (QMW, London) and Pankaj S.
Joshi (Tata Institute, Bombay) | Initial data and spherical dust collapse | 10 pages, 1 figure, accepted for publication in Physical Review D | Phys.Rev. D62 (2000) 044001 | 10.1103/PhysRevD.62.044001 | null | gr-qc | null | By considering families of radial null geodesics, we study the subsets of
initial data that lead to naked singularities and black holes in inhomogeneous
spherical dust collapse. We introduce the notion of central homogeneity for
spherical dust collapse and prove that for the occurrence of naked
singularities, the initial data set must in general be centrally homogeneous.
Even though mathematically this indicates that naked singularities are in
general unstable, we show that centrally inhomogeneous perturbations in the
initial data are not physically reasonable. This provides an example of the
fact that instability in this context deduced with respect to general
perturbations can become stabilised once the class of perturbations are
restricted to be physical.
| [
{
"created": "Thu, 17 Feb 2000 15:13:11 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Mena",
"Filipe C.",
"",
"QMW, London"
],
[
"Tavakol",
"Reza",
"",
"QMW, London"
],
[
"Joshi",
"Pankaj S.",
"",
"Tata Institute, Bombay"
]
] | By considering families of radial null geodesics, we study the subsets of initial data that lead to naked singularities and black holes in inhomogeneous spherical dust collapse. We introduce the notion of central homogeneity for spherical dust collapse and prove that for the occurrence of naked singularities, the initial data set must in general be centrally homogeneous. Even though mathematically this indicates that naked singularities are in general unstable, we show that centrally inhomogeneous perturbations in the initial data are not physically reasonable. This provides an example of the fact that instability in this context deduced with respect to general perturbations can become stabilised once the class of perturbations are restricted to be physical. |
2205.02603 | Bijan Saha Dr. | Bijan Saha | Time-dependent Spinor field in a static cylindrically-symmetric
space-time | 9 pages, 8 figures | Eur. Phys. J. Plus (2022) 137:1063 | 10.1140/epjp/s13360-022-03275-5 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Within the scope of a static cylindrically symmetric space-time we study the
behavior of a nonlinear spinor field that depends on time and radial
coordinates. It is found that the presence of nontrivial non-diagonal
components of the energy-momentum tensor (EMT) imposes some restriction on both
the metric functions and the spinor field. While for the time independent
spinor field there occur three way restrictions resembling the Bianchi type-I
Universe, in this case things become more complicated.
| [
{
"created": "Thu, 5 May 2022 12:33:00 GMT",
"version": "v1"
},
{
"created": "Tue, 20 Sep 2022 12:01:45 GMT",
"version": "v2"
}
] | 2022-09-21 | [
[
"Saha",
"Bijan",
""
]
] | Within the scope of a static cylindrically symmetric space-time we study the behavior of a nonlinear spinor field that depends on time and radial coordinates. It is found that the presence of nontrivial non-diagonal components of the energy-momentum tensor (EMT) imposes some restriction on both the metric functions and the spinor field. While for the time independent spinor field there occur three way restrictions resembling the Bianchi type-I Universe, in this case things become more complicated. |
gr-qc/9506062 | null | Giampiero Esposito and Alexander Yu. Kamenshchik | Coulomb Gauge in One-Loop Quantum Cosmology | 13 pages, plain-tex, recently appearing in Physics Letters B, volume
336, pages 324-329, September 1994. The authors apologize for the delay in
circulating the paper, due to technical problems now fixed | Phys.Lett. B336 (1994) 324-329 | 10.1016/0370-2693(94)90540-1 | null | gr-qc | null | The well-known discrepancies between covariant and non-covariant formalisms
in quantum field theory and quantum cosmology are analyzed by focusing on the
Coulomb gauge for vacuum Maxwell theory. On studying a flat Euclidean
background with boundaries, the corresponding mode-by-mode analysis of one-loop
quantum amplitudes agrees with the results of the Schwinger-DeWitt technique
and of mode-by-mode calculations in relativistic gauges.
| [
{
"created": "Tue, 27 Jun 1995 17:59:14 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Esposito",
"Giampiero",
""
],
[
"Kamenshchik",
"Alexander Yu.",
""
]
] | The well-known discrepancies between covariant and non-covariant formalisms in quantum field theory and quantum cosmology are analyzed by focusing on the Coulomb gauge for vacuum Maxwell theory. On studying a flat Euclidean background with boundaries, the corresponding mode-by-mode analysis of one-loop quantum amplitudes agrees with the results of the Schwinger-DeWitt technique and of mode-by-mode calculations in relativistic gauges. |
2308.14823 | Hector O. Silva | Hector O. Silva, Giovanni Tambalo, Kostas Glampedakis, Kent Yagi | Gravitational radiation from a particle plunging into a Schwarzschild
black hole: frequency-domain and semirelativistic analyses | 16 pages, 10 figures. v2. Matches published version | null | 10.1103/PhysRevD.109.024036 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We revisit the classic problem of gravitational wave emission by a test
particle plunging into a Schwarzschild black hole both in the frequency-domain
Regge-Wheeler-Zerilli formalism and in the semirelativistic approximation. We
use, and generalize, a transformation due to Nakamura, Sasaki, and Shibata to
improve the falloff of the source term of the Zerilli function. The faster
decay improves the numerical convergence of quantities of interest, such as the
energy radiated at spatial infinity through gravitational waves. As a test of
the method, we study the gravitational radiation produced by test particles
that plunge into the black hole with impact parameters close to the threshold
for scattering. We recover and expand upon previous results that were obtained
using the Sasaki-Nakamura equation. In particular, we study the relative
contributions to the total energy radiated due to waves of axial and polar
parity, and uncover an universal behavior in the waveforms at late times. We
complement our study with a semirelativistic analysis of the problem, and we
compare the two approaches. The generalized Nakamura-Sasaki-Shibata
transformation presented here is a simple and practical alternative for the
analysis of gravitational-wave emission by unbound orbits in the Schwarzschild
spacetime using the frequency-domain Regge-Wheeler-Zerilli formalism.
| [
{
"created": "Mon, 28 Aug 2023 18:20:50 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Jan 2024 13:00:46 GMT",
"version": "v2"
}
] | 2024-01-26 | [
[
"Silva",
"Hector O.",
""
],
[
"Tambalo",
"Giovanni",
""
],
[
"Glampedakis",
"Kostas",
""
],
[
"Yagi",
"Kent",
""
]
] | We revisit the classic problem of gravitational wave emission by a test particle plunging into a Schwarzschild black hole both in the frequency-domain Regge-Wheeler-Zerilli formalism and in the semirelativistic approximation. We use, and generalize, a transformation due to Nakamura, Sasaki, and Shibata to improve the falloff of the source term of the Zerilli function. The faster decay improves the numerical convergence of quantities of interest, such as the energy radiated at spatial infinity through gravitational waves. As a test of the method, we study the gravitational radiation produced by test particles that plunge into the black hole with impact parameters close to the threshold for scattering. We recover and expand upon previous results that were obtained using the Sasaki-Nakamura equation. In particular, we study the relative contributions to the total energy radiated due to waves of axial and polar parity, and uncover an universal behavior in the waveforms at late times. We complement our study with a semirelativistic analysis of the problem, and we compare the two approaches. The generalized Nakamura-Sasaki-Shibata transformation presented here is a simple and practical alternative for the analysis of gravitational-wave emission by unbound orbits in the Schwarzschild spacetime using the frequency-domain Regge-Wheeler-Zerilli formalism. |
2107.01421 | Burkhard Kleihaus | Efthimia Deligianni, Burkhard Kleihaus, Jutta Kunz, Petya Nedkova,
Stoytcho Yazadjiev | Quasi-periodic Oscillations in Rotating Ellis Wormhole Spacetimes | 21 pages, 16 figures | Phys. Rev. D 104, 064043 (2021) | 10.1103/PhysRevD.104.064043 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyze the properties of the circular orbits for massive particles in the
equatorial plane of symmetric rotating Ellis wormholes. In particular, we
obtain the orbital frequencies and the radial and vertical epicyclic
frequencies, and consider their lowest parametric, forced and Keplerian
resonances. These show that quasi-periodic oscillations in accretion disks
around symmetric rotating Ellis wormholes have many distinct properties as
compared to quasi-periodic oscillations in accretion disks around rotating Teo
wormholes and the Kerr black hole. Still we can distinguish some common
features which appear in wormhole spacetimes as opposed to black holes. The
most significant ones include the possibility of excitation of stronger
resonances such as lower order parametric and forced resonances and the
localization of these resonances deep in the region of strong gravitational
interaction near the wormhole throat, which will lead to further amplification
of the signal.
| [
{
"created": "Sat, 3 Jul 2021 12:30:47 GMT",
"version": "v1"
}
] | 2021-09-22 | [
[
"Deligianni",
"Efthimia",
""
],
[
"Kleihaus",
"Burkhard",
""
],
[
"Kunz",
"Jutta",
""
],
[
"Nedkova",
"Petya",
""
],
[
"Yazadjiev",
"Stoytcho",
""
]
] | We analyze the properties of the circular orbits for massive particles in the equatorial plane of symmetric rotating Ellis wormholes. In particular, we obtain the orbital frequencies and the radial and vertical epicyclic frequencies, and consider their lowest parametric, forced and Keplerian resonances. These show that quasi-periodic oscillations in accretion disks around symmetric rotating Ellis wormholes have many distinct properties as compared to quasi-periodic oscillations in accretion disks around rotating Teo wormholes and the Kerr black hole. Still we can distinguish some common features which appear in wormhole spacetimes as opposed to black holes. The most significant ones include the possibility of excitation of stronger resonances such as lower order parametric and forced resonances and the localization of these resonances deep in the region of strong gravitational interaction near the wormhole throat, which will lead to further amplification of the signal. |
gr-qc/0104057 | Carlo Rovelli | Louis Crane, Alejandro Perez, Carlo Rovelli | A finiteness proof for the Lorentzian state sum spinfoam model for
quantum general relativity | 11 pages, 3 pictures | null | null | null | gr-qc | null | We show that the normalized Lorentzian state sum is finite on any
triangulation. It thus provides a candidate for a perturbatively finite quantum
theory of general relativity in four dimensions with Lorentzian signature.
| [
{
"created": "Wed, 18 Apr 2001 10:19:30 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Crane",
"Louis",
""
],
[
"Perez",
"Alejandro",
""
],
[
"Rovelli",
"Carlo",
""
]
] | We show that the normalized Lorentzian state sum is finite on any triangulation. It thus provides a candidate for a perturbatively finite quantum theory of general relativity in four dimensions with Lorentzian signature. |
1603.04469 | Sam Dolan Dr | Jake O Shipley and Sam R Dolan | Binary black hole shadows, chaotic scattering and the Cantor set | 38 pages, 21 figures. Minor improvements. Added Fig. 8 and Appendix B | Class.Quant.Grav. 33 (2016) no.17, 175001 | 10.1088/0264-9381/33/17/175001 | null | gr-qc astro-ph.GA nlin.CD | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the qualitative features of binary black hole shadows using
the model of two extremally charged black holes in static equilibrium (a
Majumdar--Papapetrou solution). Our perspective is that binary spacetimes are
natural exemplars of chaotic scattering, because they admit more than one
fundamental null orbit, and thus an uncountably-infinite set of perpetual null
orbits which generate scattering singularities in initial data. Inspired by the
three-disc model, we develop an appropriate symbolic dynamics to describe
planar null geodesics on the double black hole spacetime. We show that a
one-dimensional (1D) black hole shadow may constructed through an iterative
procedure akin to the construction of the Cantor set; thus the 1D shadow is
self-similar. Next, we study non-planar rays, to understand how angular
momentum affects the existence and properties of the fundamental null orbits.
Taking slices through 2D shadows, we observe three types of 1D shadow: regular,
Cantor-like, and highly chaotic. The switch from Cantor-like to regular occurs
where outer fundamental orbits are forbidden by angular momentum. The highly
chaotic part is associated with an unexpected feature: stable and bounded null
orbits, which exist around two black holes of equal mass $M$ separated by $a_1
< a < \sqrt{2} a_1$, where $a_1 = 4M/\sqrt{27}$. To show how this possibility
arises, we define a certain potential function and classify its stationary
points. We conjecture that the highly chaotic parts of the 2D shadow possess
the Wada property. Finally, we consider the possibility of following null
geodesics through event horizons, and chaos in the maximally-extended
spacetime.
| [
{
"created": "Mon, 14 Mar 2016 21:00:04 GMT",
"version": "v1"
},
{
"created": "Thu, 31 Mar 2016 14:19:43 GMT",
"version": "v2"
},
{
"created": "Thu, 9 Jun 2016 15:17:12 GMT",
"version": "v3"
}
] | 2016-08-09 | [
[
"Shipley",
"Jake O",
""
],
[
"Dolan",
"Sam R",
""
]
] | We investigate the qualitative features of binary black hole shadows using the model of two extremally charged black holes in static equilibrium (a Majumdar--Papapetrou solution). Our perspective is that binary spacetimes are natural exemplars of chaotic scattering, because they admit more than one fundamental null orbit, and thus an uncountably-infinite set of perpetual null orbits which generate scattering singularities in initial data. Inspired by the three-disc model, we develop an appropriate symbolic dynamics to describe planar null geodesics on the double black hole spacetime. We show that a one-dimensional (1D) black hole shadow may constructed through an iterative procedure akin to the construction of the Cantor set; thus the 1D shadow is self-similar. Next, we study non-planar rays, to understand how angular momentum affects the existence and properties of the fundamental null orbits. Taking slices through 2D shadows, we observe three types of 1D shadow: regular, Cantor-like, and highly chaotic. The switch from Cantor-like to regular occurs where outer fundamental orbits are forbidden by angular momentum. The highly chaotic part is associated with an unexpected feature: stable and bounded null orbits, which exist around two black holes of equal mass $M$ separated by $a_1 < a < \sqrt{2} a_1$, where $a_1 = 4M/\sqrt{27}$. To show how this possibility arises, we define a certain potential function and classify its stationary points. We conjecture that the highly chaotic parts of the 2D shadow possess the Wada property. Finally, we consider the possibility of following null geodesics through event horizons, and chaos in the maximally-extended spacetime. |
1111.4702 | Bahram Mashhoon | C. Chicone and B. Mashhoon | Nonlocal Gravity: Modified Poisson's Equation | 27 pages, 4 figures; v2: minor improvements, accepted for publication
in J. Math. Phys | J.Math.Phys.53:042501,2012 | 10.1063/1.3702449 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The recent nonlocal generalization of Einstein's theory of gravitation
reduces in the Newtonian regime to a nonlocal and nonlinear modification of
Poisson's equation of Newtonian gravity. The nonlocally modified Poisson
equation implies that nonlocality can simulate dark matter. Observational data
regarding dark matter provide limited information about the functional form of
the reciprocal kernel, from which the original nonlocal kernel of the theory
must be determined. We study this inverse problem of nonlocal gravity in the
linear domain, where the applicability of the Fourier transform method is
critically examined and the conditions for the existence of the nonlocal kernel
are discussed. This approach is illustrated via simple explicit examples for
which the kernels are numerically evaluated. We then turn to a general
discussion of the modified Poisson equation and present a formal solution of
this equation via a successive approximation scheme. The treatment is
specialized to the gravitational potential of a point mass, where in the linear
regime we recover the Tohline-Kuhn approach to modified gravity.
| [
{
"created": "Sun, 20 Nov 2011 23:36:44 GMT",
"version": "v1"
},
{
"created": "Fri, 13 Apr 2012 17:29:11 GMT",
"version": "v2"
}
] | 2015-06-03 | [
[
"Chicone",
"C.",
""
],
[
"Mashhoon",
"B.",
""
]
] | The recent nonlocal generalization of Einstein's theory of gravitation reduces in the Newtonian regime to a nonlocal and nonlinear modification of Poisson's equation of Newtonian gravity. The nonlocally modified Poisson equation implies that nonlocality can simulate dark matter. Observational data regarding dark matter provide limited information about the functional form of the reciprocal kernel, from which the original nonlocal kernel of the theory must be determined. We study this inverse problem of nonlocal gravity in the linear domain, where the applicability of the Fourier transform method is critically examined and the conditions for the existence of the nonlocal kernel are discussed. This approach is illustrated via simple explicit examples for which the kernels are numerically evaluated. We then turn to a general discussion of the modified Poisson equation and present a formal solution of this equation via a successive approximation scheme. The treatment is specialized to the gravitational potential of a point mass, where in the linear regime we recover the Tohline-Kuhn approach to modified gravity. |
gr-qc/9908001 | Clovis Jacinto de Matos | Clovis J. de Matos and Robert E. Becker | Gravitomagnetic Flux Quantization in superconductors and a Method for
the Experimental Detection of Gravitomagnetism in the Terrestrial Laboratory | 36 pages, 3 figures. This article does not reflect the position of
any official instituion. The ideas exposed still evolving | null | null | null | gr-qc | null | It is extraordinarely difficult to detect the extremely weak gravitomagnetic
(GM) field of even as large a body as the earth. To detect the GM field, the
gravitational analog of an ordinary magnetic field, in a modest terrestrial
laboratory should be that much more difficult. Here we show, however, that for
certain superconductor configuration and topologies, it should be possible to
detect a measurable GM field in the terrestrial laboratory, by using the
properties of superconductors imposed by quantum mechanical requirements. In
particular, we show that the GM Flux should be quantized in a superconductor
with non-vanishing genus, just like the ordinary magnetic flux. And this
magnetically induced, quantized GM Flux, for sufficiently high quantum number
and favorable geometries, should be distinguishable from the effects produced
by an ordinary magnetic field.
| [
{
"created": "Sat, 31 Jul 1999 00:25:01 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"de Matos",
"Clovis J.",
""
],
[
"Becker",
"Robert E.",
""
]
] | It is extraordinarely difficult to detect the extremely weak gravitomagnetic (GM) field of even as large a body as the earth. To detect the GM field, the gravitational analog of an ordinary magnetic field, in a modest terrestrial laboratory should be that much more difficult. Here we show, however, that for certain superconductor configuration and topologies, it should be possible to detect a measurable GM field in the terrestrial laboratory, by using the properties of superconductors imposed by quantum mechanical requirements. In particular, we show that the GM Flux should be quantized in a superconductor with non-vanishing genus, just like the ordinary magnetic flux. And this magnetically induced, quantized GM Flux, for sufficiently high quantum number and favorable geometries, should be distinguishable from the effects produced by an ordinary magnetic field. |
0710.2014 | Francesco Belgiorno | F. Belgiorno and S. L. Cacciatori | Quantum Effects for the Dirac Field in Reissner-Nordstrom-AdS Black Hole
Background | 18 pages, 5 figures, Iop style | Class.Quant.Grav.25:105013,2008 | 10.1088/0264-9381/25/10/105013 | null | gr-qc | null | The behavior of a charged massive Dirac field on a Reissner-Nordstrom-AdS
black hole background is investigated. The essential self-adjointness of the
Dirac Hamiltonian is studied. Then, an analysis of the discharge problem is
carried out in analogy with the standard Reissner-Nordstrom black hole case.
| [
{
"created": "Wed, 10 Oct 2007 13:59:44 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Belgiorno",
"F.",
""
],
[
"Cacciatori",
"S. L.",
""
]
] | The behavior of a charged massive Dirac field on a Reissner-Nordstrom-AdS black hole background is investigated. The essential self-adjointness of the Dirac Hamiltonian is studied. Then, an analysis of the discharge problem is carried out in analogy with the standard Reissner-Nordstrom black hole case. |
gr-qc/0504010 | Andrew Randono | Andrew Randono | A Generalization of the Kodama State for Arbitrary Values of the Immirzi
Parameter | 16 pages | null | null | null | gr-qc | null | The Kodama State for Lorentzian gravity presupposes a particular value for
the Immirzi-parameter, namely $\beta=-i$. However, the derivation of black hole
entropy in Loop Quantum Gravity suggests that the Immirzi parameter is a fixed
value whose magnitude is on the order of unity but larger than one. Since the
Kodama state has de-Sitter spacetime as its classical limit, to get the proper
radiation temperature, the Kodama state should be extended to incorporate a
more physical value for $\beta$. Thus, we present an extension of the Kodama
state for arbitrary values of the Immirzi parameter, $\beta$, that reduces to
the ordinary Chern-Simons state for the particular value $\beta=-i$. The state
for real values of $\beta$ is free of several of the outstanding problems that
cast doubts on the original Kodama state as a ground state for quantum general
relativity. We show that for real values of $\beta$, the state is invariant
under large gauge transformations, it is CPT invariant (but not CP invariant),
and it is expected to be delta-function normalizable with respect to the
kinematical inner product. To aid in the construction, we first present a
general method for solving the Hamiltonian constraint for imaginary values of
$\beta$ that allows one to use the simpler self-dual and anti-self-dual forms
of the constraint as an intermediate step.
| [
{
"created": "Sat, 2 Apr 2005 23:48:41 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Randono",
"Andrew",
""
]
] | The Kodama State for Lorentzian gravity presupposes a particular value for the Immirzi-parameter, namely $\beta=-i$. However, the derivation of black hole entropy in Loop Quantum Gravity suggests that the Immirzi parameter is a fixed value whose magnitude is on the order of unity but larger than one. Since the Kodama state has de-Sitter spacetime as its classical limit, to get the proper radiation temperature, the Kodama state should be extended to incorporate a more physical value for $\beta$. Thus, we present an extension of the Kodama state for arbitrary values of the Immirzi parameter, $\beta$, that reduces to the ordinary Chern-Simons state for the particular value $\beta=-i$. The state for real values of $\beta$ is free of several of the outstanding problems that cast doubts on the original Kodama state as a ground state for quantum general relativity. We show that for real values of $\beta$, the state is invariant under large gauge transformations, it is CPT invariant (but not CP invariant), and it is expected to be delta-function normalizable with respect to the kinematical inner product. To aid in the construction, we first present a general method for solving the Hamiltonian constraint for imaginary values of $\beta$ that allows one to use the simpler self-dual and anti-self-dual forms of the constraint as an intermediate step. |
1408.2415 | Abraao Capistrano | A.J.S Capistrano | Smooth deformations and cosmic statefinders | 12 pages, 6 figures | MNRAS (April 1, 2015) 448 (2): 1232-1239 | 10.1093/mnras/stv052 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the possibility that the universe is subjected to a deformation,
besides its expansion described by Friedmann's equations. The concept of smooth
deformation of a riemannian manifolds associated with the extrinsic curvature
is applied the standard FLRW cosmology. Starting from the resulting modified
Friedman's equation we study two possible solutions with six models for each
one in low redshift. In other to constrain the models, we calculate
deceleration, jerk and Hubble parameters and compare with different data as the
latest BAO/CMB + SNIa constraints, SNLS SNIa, x-ray galaxy clusters and the
gold sample (SNIa). As a result, we obtain a set of proper models compatible
with the current observational data.
| [
{
"created": "Fri, 8 Aug 2014 00:06:38 GMT",
"version": "v1"
},
{
"created": "Wed, 12 Nov 2014 22:53:15 GMT",
"version": "v2"
}
] | 2016-06-01 | [
[
"Capistrano",
"A. J. S",
""
]
] | We study the possibility that the universe is subjected to a deformation, besides its expansion described by Friedmann's equations. The concept of smooth deformation of a riemannian manifolds associated with the extrinsic curvature is applied the standard FLRW cosmology. Starting from the resulting modified Friedman's equation we study two possible solutions with six models for each one in low redshift. In other to constrain the models, we calculate deceleration, jerk and Hubble parameters and compare with different data as the latest BAO/CMB + SNIa constraints, SNLS SNIa, x-ray galaxy clusters and the gold sample (SNIa). As a result, we obtain a set of proper models compatible with the current observational data. |
2301.11821 | Stephen Adler | Stephen L. Adler | Dynamical gravastars may evade no-go results for exotic compact objects,
together with further analytical and numerical results for the dynamical
gravastar model | 23 pages; introduction expanded, and Sec. 8 on time delays added | Physical Review D 109, 024020 (2024) | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using graphs plotted from the Mathematica notebooks posted with our paper
``Dynamical Gravastars'', we show that a dynamical gravastar has no hard
surface, and that a second light sphere resides in the deep interior where
there is maximum time dilation. These facts may permit dynamical gravastars to
evade no-go results for exotic compact objects relating to light leakage inside
the shadow, and nonlinear instabilities arising from an interior light sphere.
Testing these surmises will require further detailed modeling calculations,
beyond what we commence in this paper, using the numerical dynamical gravastar
solution. We also discuss the effect of replacing the sigmoidal function in the
gravastar calculation by a unit step function, and we analyze why the dynamical
gravastar evades the singularities predicted by the Penrose and Hawking
singularity theorems, despite satisfying both the null and strong energy
conditions. We then give a simplified two-step process for tuning the initial
value $\nu(0)={\rm nuinit}$ to achieve $\nu(\infty)=0$, and give exact
integrals for the pressure differential equation in terms of $\nu(r)$ in the
interior and exterior regions. Finally, we briefly discuss an extension of the
model that includes an external shell of massive particles.
| [
{
"created": "Fri, 27 Jan 2023 16:22:07 GMT",
"version": "v1"
},
{
"created": "Mon, 30 Jan 2023 17:05:45 GMT",
"version": "v2"
},
{
"created": "Mon, 13 Feb 2023 21:03:23 GMT",
"version": "v3"
},
{
"created": "Tue, 14 Mar 2023 15:21:17 GMT",
"version": "v4"
},
{
"created": "Wed, 24 May 2023 15:22:39 GMT",
"version": "v5"
},
{
"created": "Thu, 25 May 2023 01:03:23 GMT",
"version": "v6"
},
{
"created": "Sun, 25 Jun 2023 19:44:07 GMT",
"version": "v7"
},
{
"created": "Thu, 28 Sep 2023 18:22:41 GMT",
"version": "v8"
},
{
"created": "Mon, 18 Dec 2023 17:15:43 GMT",
"version": "v9"
}
] | 2024-02-13 | [
[
"Adler",
"Stephen L.",
""
]
] | Using graphs plotted from the Mathematica notebooks posted with our paper ``Dynamical Gravastars'', we show that a dynamical gravastar has no hard surface, and that a second light sphere resides in the deep interior where there is maximum time dilation. These facts may permit dynamical gravastars to evade no-go results for exotic compact objects relating to light leakage inside the shadow, and nonlinear instabilities arising from an interior light sphere. Testing these surmises will require further detailed modeling calculations, beyond what we commence in this paper, using the numerical dynamical gravastar solution. We also discuss the effect of replacing the sigmoidal function in the gravastar calculation by a unit step function, and we analyze why the dynamical gravastar evades the singularities predicted by the Penrose and Hawking singularity theorems, despite satisfying both the null and strong energy conditions. We then give a simplified two-step process for tuning the initial value $\nu(0)={\rm nuinit}$ to achieve $\nu(\infty)=0$, and give exact integrals for the pressure differential equation in terms of $\nu(r)$ in the interior and exterior regions. Finally, we briefly discuss an extension of the model that includes an external shell of massive particles. |
1204.3667 | Hideyoshi Arakida | Hideyoshi Arakida | Effect of inhomogeneity of the Universe on a gravitationally bound local
system: A no-go result for explaining the secular increase in the
astronomical unit | 12 pages, no figure, accepted for publication in Journal of
Astrophysics and Astronomy | null | 10.1007/s12036-012-9142-8 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We will investigate the influence of the inhomogeneity of the universe,
especially that of the Lema{\^i}tre-Tolman-Bondi (LTB) model, on a
gravitationally bound local system such as the solar system. We concentrate on
the dynamical perturbation to the planetary motion and derive the leading order
effect generated from the LTB model. It will be shown that there appear not
only a well-known cosmological effect arisen from the homogeneous and isotropic
model, such as the Robertson-Walker (RW) model, but also the additional terms
due to the radial inhomogeneity of the LTB model. We will also apply the
obtained results to the problem of secular increase in the astronomical unit,
reported by Krasinsky and Brumberg (2004), and imply that the inhomogeneity of
the universe cannot have a significant effect for explaining the observed
$d{\rm AU}/dt = 15 \pm 4 ~{\rm [m/century]}$.
| [
{
"created": "Mon, 16 Apr 2012 23:30:58 GMT",
"version": "v1"
}
] | 2015-06-04 | [
[
"Arakida",
"Hideyoshi",
""
]
] | We will investigate the influence of the inhomogeneity of the universe, especially that of the Lema{\^i}tre-Tolman-Bondi (LTB) model, on a gravitationally bound local system such as the solar system. We concentrate on the dynamical perturbation to the planetary motion and derive the leading order effect generated from the LTB model. It will be shown that there appear not only a well-known cosmological effect arisen from the homogeneous and isotropic model, such as the Robertson-Walker (RW) model, but also the additional terms due to the radial inhomogeneity of the LTB model. We will also apply the obtained results to the problem of secular increase in the astronomical unit, reported by Krasinsky and Brumberg (2004), and imply that the inhomogeneity of the universe cannot have a significant effect for explaining the observed $d{\rm AU}/dt = 15 \pm 4 ~{\rm [m/century]}$. |
2209.02268 | Shao-Jun Zhang | Shao-Jun Zhang, Bin Wang, Eleftherios Papantonopoulos, Anzhong Wang | Magnetic-induced Spontaneous Scalarization in Dynamcial Chern-Simons
Gravity | 23 pages, 4 figures, a few more data and comments added to match the
published version | Eur.Phys.J.C (2023) 83:97 | 10.1140/epjc/s10052-023-11254-y | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the framework of the dynamical Chern-Simons gravity, we study the scalar
field perturbations of the Reissner-Nordstr\"{o}m-Melvin spacetime, which
describes a charged black hole permeated by a uniform magnetic field. In the
presence of the magnetic field, the scalar field acquires an effective mass
whose square takes negative value in the half domain of the angular direction.
This inevitably introduces the tachyonic instability and associated spontaneous
scalarization as long as the coupling constant between the scalar field and the
Chern-Simons invariant exceeds a threshold value. We study the object pictures
of the time evolutions of the scalar field perturbations at the linear level,
and find that the presence of the magnetic field will dramatically change the
waveforms and associated ringdown modes. Nonlinear evolutions for the unstable
perturbations are also performed in the decoupling limit, which demonstrate the
scalar cloud as the final fate. Influences of the coupling constant and the
black hole charge on the wave dynamics are also studied.
| [
{
"created": "Tue, 6 Sep 2022 07:35:12 GMT",
"version": "v1"
},
{
"created": "Tue, 31 Jan 2023 21:49:01 GMT",
"version": "v2"
}
] | 2023-02-02 | [
[
"Zhang",
"Shao-Jun",
""
],
[
"Wang",
"Bin",
""
],
[
"Papantonopoulos",
"Eleftherios",
""
],
[
"Wang",
"Anzhong",
""
]
] | In the framework of the dynamical Chern-Simons gravity, we study the scalar field perturbations of the Reissner-Nordstr\"{o}m-Melvin spacetime, which describes a charged black hole permeated by a uniform magnetic field. In the presence of the magnetic field, the scalar field acquires an effective mass whose square takes negative value in the half domain of the angular direction. This inevitably introduces the tachyonic instability and associated spontaneous scalarization as long as the coupling constant between the scalar field and the Chern-Simons invariant exceeds a threshold value. We study the object pictures of the time evolutions of the scalar field perturbations at the linear level, and find that the presence of the magnetic field will dramatically change the waveforms and associated ringdown modes. Nonlinear evolutions for the unstable perturbations are also performed in the decoupling limit, which demonstrate the scalar cloud as the final fate. Influences of the coupling constant and the black hole charge on the wave dynamics are also studied. |
gr-qc/9806072 | Chris J. Fama | C. J. Fama and C. J. S. Clarke | A rigidity result on the ideal boundary structure of smooth space-times | 14 pages, 2 figures; to appear in Clas. Quant. Grav | Class.Quant.Grav. 15 (1998) 2829-2840 | 10.1088/0264-9381/15/9/027 | null | gr-qc math.DG | null | Following a survey of the abstract boundary definition of Scott and Szekeres,
a rigidity result is proved for the smooth case, showing that the topological
structure of the regular part of this boundary in invariantly defined.
| [
{
"created": "Wed, 17 Jun 1998 13:45:05 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Fama",
"C. J.",
""
],
[
"Clarke",
"C. J. S.",
""
]
] | Following a survey of the abstract boundary definition of Scott and Szekeres, a rigidity result is proved for the smooth case, showing that the topological structure of the regular part of this boundary in invariantly defined. |
gr-qc/9506061 | null | Giampiero Esposito, Alexander Yu. Kamenshchik, Igor V. Mishakov,
Giuseppe Pollifrone | Euclidean Maxwell Theory in the Presence of Boundaries. II | 24 pages, plain-tex, recently appearing in Classical and Quantum
Gravity, volume 11, pages 2939-2950, December 1994. The authors apologize for
the delay in circulating the file, due to technical problems now fixed | Class.Quant.Grav.11:2939-2950,1994 | 10.1088/0264-9381/11/12/009 | null | gr-qc | null | Zeta-function regularization is applied to complete a recent analysis of the
quantized electromagnetic field in the presence of boundaries. The quantum
theory is studied by setting to zero on the boundary the magnetic field, the
gauge-averaging functional and hence the Faddeev-Popov ghost field. Electric
boundary conditions are also studied. On considering two gauge functionals
which involve covariant derivatives of the 4-vector potential, a series of
detailed calculations shows that, in the case of flat Euclidean 4-space bounded
by two concentric 3-spheres, one-loop quantum amplitudes are gauge independent
and their mode-by-mode evaluation agrees with the covariant formulae for such
amplitudes and coincides for magnetic or electric boundary conditions. By
contrast, if a single 3-sphere boundary is studied, one finds some
inconsistencies, i.e. gauge dependence of the amplitudes.
| [
{
"created": "Tue, 27 Jun 1995 17:44:45 GMT",
"version": "v1"
}
] | 2010-04-06 | [
[
"Esposito",
"Giampiero",
""
],
[
"Kamenshchik",
"Alexander Yu.",
""
],
[
"Mishakov",
"Igor V.",
""
],
[
"Pollifrone",
"Giuseppe",
""
]
] | Zeta-function regularization is applied to complete a recent analysis of the quantized electromagnetic field in the presence of boundaries. The quantum theory is studied by setting to zero on the boundary the magnetic field, the gauge-averaging functional and hence the Faddeev-Popov ghost field. Electric boundary conditions are also studied. On considering two gauge functionals which involve covariant derivatives of the 4-vector potential, a series of detailed calculations shows that, in the case of flat Euclidean 4-space bounded by two concentric 3-spheres, one-loop quantum amplitudes are gauge independent and their mode-by-mode evaluation agrees with the covariant formulae for such amplitudes and coincides for magnetic or electric boundary conditions. By contrast, if a single 3-sphere boundary is studied, one finds some inconsistencies, i.e. gauge dependence of the amplitudes. |
2012.12875 | Kai Flathmann | Kai Flathmann, Manuel Hohmann | Post-Newtonian limit of generalized symmetric teleparallel gravity | 13 pages | Phys. Rev. D 103, 044030 (2021) | 10.1103/PhysRevD.103.044030 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this article we analyze the post-Newtonian approximation of a
generalization of the symmetric teleparallel gravity with the help of the
parameterized post-Newtonian (PPN) formalism. This class of theories is based
on a free function of the five independent quadratic contractions of the
non-metricity tensor. By calculating the PPN metric of these theories, we can
restrict the Taylor coefficients of the free function with the help of the PPN
parameters and their observational bounds. We find two families of theories
whose PPN parameters are identical to those of general relativity, and thus in
full agreement with observations. For three further families, we find that only
the PPN parameters $\beta$ and $\gamma$ deviate, but can be brought arbitrarily
close to their general relativity values by an appropriate choice of the
Lagrangian, so that also these families contain candidate theories which agree
with observations. The remaining theories either possess no well-defined
solution of the post-Newtonian field equations, or possess a post-Newtonian
limit which exceeds the form assumed in the PPN formalism.
| [
{
"created": "Wed, 23 Dec 2020 18:40:05 GMT",
"version": "v1"
}
] | 2021-02-24 | [
[
"Flathmann",
"Kai",
""
],
[
"Hohmann",
"Manuel",
""
]
] | In this article we analyze the post-Newtonian approximation of a generalization of the symmetric teleparallel gravity with the help of the parameterized post-Newtonian (PPN) formalism. This class of theories is based on a free function of the five independent quadratic contractions of the non-metricity tensor. By calculating the PPN metric of these theories, we can restrict the Taylor coefficients of the free function with the help of the PPN parameters and their observational bounds. We find two families of theories whose PPN parameters are identical to those of general relativity, and thus in full agreement with observations. For three further families, we find that only the PPN parameters $\beta$ and $\gamma$ deviate, but can be brought arbitrarily close to their general relativity values by an appropriate choice of the Lagrangian, so that also these families contain candidate theories which agree with observations. The remaining theories either possess no well-defined solution of the post-Newtonian field equations, or possess a post-Newtonian limit which exceeds the form assumed in the PPN formalism. |
gr-qc/0509119 | Gioel Calabrese | Gioel Calabrese and Carsten Gundlach | Discrete boundary treatment for the shifted wave equation | 27 pages, 2 figures. Revised version | Class.Quant.Grav. 23 (2006) S343-S368 | 10.1088/0264-9381/23/16/S04 | null | gr-qc | null | We present strongly stable semi-discrete finite difference approximations to
the quarter space problem (x>0, t>0) for the first order in time, second order
in space wave equation with a shift term. We consider space-like (pure outflow)
and time-like boundaries, with either second or fourth order accuracy. These
discrete boundary conditions suggest a general prescription for boundary
conditions in finite difference codes approximating first order in time, second
order in space hyperbolic problems, such as those that appear in numerical
relativity. As an example we construct boundary conditions for the
Nagy-Ortiz-Reula formulation of the Einstein equations coupled to a scalar
field in spherical symmetry.
| [
{
"created": "Thu, 29 Sep 2005 15:55:47 GMT",
"version": "v1"
},
{
"created": "Mon, 31 Jul 2006 10:31:33 GMT",
"version": "v2"
}
] | 2024-07-11 | [
[
"Calabrese",
"Gioel",
""
],
[
"Gundlach",
"Carsten",
""
]
] | We present strongly stable semi-discrete finite difference approximations to the quarter space problem (x>0, t>0) for the first order in time, second order in space wave equation with a shift term. We consider space-like (pure outflow) and time-like boundaries, with either second or fourth order accuracy. These discrete boundary conditions suggest a general prescription for boundary conditions in finite difference codes approximating first order in time, second order in space hyperbolic problems, such as those that appear in numerical relativity. As an example we construct boundary conditions for the Nagy-Ortiz-Reula formulation of the Einstein equations coupled to a scalar field in spherical symmetry. |
2112.11162 | Hrvoje Nikolic | Hrvoje Nikolic | Submarine paradox softened | 8 pages, 1 figure, significantly revised and extended, accepted for
publication in Am. J. Phys | Am. J. Phys. 90, 841 (2022) | 10.1119/5.0084185 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In Supplee's submarine paradox, a naive argument based on Lorentz contraction
leads to a contradiction that a fast submarine should sink in the water's
reference frame but float in the submarine's reference frame. Due to the
submarine's rigidity constraints, it is not easy to resolve the paradox in a
manifestly covariant form. To simplify the problem, we consider a version of
the paradox in which one fluid moves through another fluid. An analysis of
ideal relativistic fluids in a weak gravitational field shows that the moving
fluid has a larger pressure and hence sinks, in agreement with known results
for the rigid submarine.
| [
{
"created": "Tue, 21 Dec 2021 12:57:39 GMT",
"version": "v1"
},
{
"created": "Wed, 29 Dec 2021 10:02:00 GMT",
"version": "v2"
},
{
"created": "Tue, 2 Aug 2022 05:56:45 GMT",
"version": "v3"
}
] | 2024-06-19 | [
[
"Nikolic",
"Hrvoje",
""
]
] | In Supplee's submarine paradox, a naive argument based on Lorentz contraction leads to a contradiction that a fast submarine should sink in the water's reference frame but float in the submarine's reference frame. Due to the submarine's rigidity constraints, it is not easy to resolve the paradox in a manifestly covariant form. To simplify the problem, we consider a version of the paradox in which one fluid moves through another fluid. An analysis of ideal relativistic fluids in a weak gravitational field shows that the moving fluid has a larger pressure and hence sinks, in agreement with known results for the rigid submarine. |
1909.02434 | T. P. Singh | Palemkota Maithresh and Tejinder P. Singh | Black hole entropy from trace dynamics and non-commutative geometry | v2: 29 pages, one figure. Significantly revised, including change of
title. Background material included [from arXiv:1903.05402 [gr-qc],
arXiv:1905.08248 [gr-qc], arXiv:1908.04309 [gr-qc]] so as to make this paper
self-contained and more easily readable. Derivation of Bekenstein-Hawking
entropy remains unchanged | null | null | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Spontaneous localisation is a falsifiable, phenomenological, mechanism for
explaining the absence of macroscopic position superpositions, currently being
tested for in the laboratory. The theory of trace dynamics provides a possible
theoretical origin for spontaneous localisation. We have recently proposed how
to employ non-commutative geometry to include gravity in trace dynamics, and
suggested the emergence of classical space-time geometry via spontaneous
localisation. In our theory, which we call non-commutative matter gravity, a
black hole arises from the spontaneous localisation of an entangled state of a
large number of `atoms of space-time-matter [STM]'. Prior to localisation, the
non-commutative curvature of an STM atom is described by the spectral action of
non-commutative geometry. By using the techniques of statistical thermodynamics
from trace dynamics, we show that the gravitational entropy of a Schwarzschild
black hole results from the microstates of the entangled STM atoms and is given
(subject to certain assumptions) by the classical Euclidean gravitational
action. This action, in turn, equals the Bekenstein-Hawking entropy
(Area/$4{L_P}^2$) of the black hole. We argue that spontaneous localisation is
related to black-hole evaporation through the fluctuation-dissipation theorem.
| [
{
"created": "Thu, 5 Sep 2019 14:16:54 GMT",
"version": "v1"
},
{
"created": "Tue, 7 Jan 2020 17:25:43 GMT",
"version": "v2"
}
] | 2020-01-08 | [
[
"Maithresh",
"Palemkota",
""
],
[
"Singh",
"Tejinder P.",
""
]
] | Spontaneous localisation is a falsifiable, phenomenological, mechanism for explaining the absence of macroscopic position superpositions, currently being tested for in the laboratory. The theory of trace dynamics provides a possible theoretical origin for spontaneous localisation. We have recently proposed how to employ non-commutative geometry to include gravity in trace dynamics, and suggested the emergence of classical space-time geometry via spontaneous localisation. In our theory, which we call non-commutative matter gravity, a black hole arises from the spontaneous localisation of an entangled state of a large number of `atoms of space-time-matter [STM]'. Prior to localisation, the non-commutative curvature of an STM atom is described by the spectral action of non-commutative geometry. By using the techniques of statistical thermodynamics from trace dynamics, we show that the gravitational entropy of a Schwarzschild black hole results from the microstates of the entangled STM atoms and is given (subject to certain assumptions) by the classical Euclidean gravitational action. This action, in turn, equals the Bekenstein-Hawking entropy (Area/$4{L_P}^2$) of the black hole. We argue that spontaneous localisation is related to black-hole evaporation through the fluctuation-dissipation theorem. |
1805.10683 | H{\aa}kan Andr\'easson | H{\aa}kan Andr\'easson, Markus Kunze | Comments on the paper 'Static solutions of the Vlasov-Einstein system'
by G. Wolansky | 9 pages | Arch. Ration. Mech. Anal. 235, 783-791 (2020) | 10.1007/s00205-019-01432-2 | null | gr-qc math.AP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this note we address the attempted proof of the existence of static
solutions to the Einstein-Vlasov system as given in \cite{Wol}. We focus on a
specific and central part of the proof which concerns a variational problem
with an obstacle. We show that two important claims in \cite{Wol} are incorrect
and we question the validity of a third claim. We also discuss the variational
problem and its difficulties with the aim to stimulate further investigations
of this intriguing problem: to answer the question whether or not static
solutions of the Einstein-Vlasov system can be found as local minimizers of an
energy-Casimir functional.
| [
{
"created": "Sun, 27 May 2018 20:43:37 GMT",
"version": "v1"
}
] | 2024-02-19 | [
[
"Andréasson",
"Håkan",
""
],
[
"Kunze",
"Markus",
""
]
] | In this note we address the attempted proof of the existence of static solutions to the Einstein-Vlasov system as given in \cite{Wol}. We focus on a specific and central part of the proof which concerns a variational problem with an obstacle. We show that two important claims in \cite{Wol} are incorrect and we question the validity of a third claim. We also discuss the variational problem and its difficulties with the aim to stimulate further investigations of this intriguing problem: to answer the question whether or not static solutions of the Einstein-Vlasov system can be found as local minimizers of an energy-Casimir functional. |
gr-qc/0701151 | Matyas Vasuth | L\'aszl\'o \'A. Gergely, Zolt\'an I. Perj\'es and M\'aty\'as Vas\'uth | Generalized true- and eccentric-anomaly parametrizations for the
perturbed Kepler motion | null | Proceedings of the Ninth Marcel Grossmann Meeting 2000 on Recent
Developments in Theoretical and Experimental General Relativity, Gravitation
and Relativistic Field Theories. Eds. VG Gurzadyan, RT Jantzen and R Ruffini,
World Scientific, Singapore, p.1751-1752 (2002) | null | null | gr-qc | null | The true- and eccentric-anomaly parametrizations of the Kepler motion are
generalized to quasiperiodic orbits by considering perturbations of the radial
part of kinetic energy as a series in the negative powers of the orbital
radius. A toolbox of methods for averaging observables in terms of the energy
$E$ and angular momentum $L$ is developed. A broad range of systems governed by
the generic Brumberg force, as well as recent applications of the theory of
gravitational radiation involve integrals over a period of motion. These
integrals are evaluated by using the residue theorem. It is shown that the pole
of the integrand is located in the origin and that under certain circumstances
an additional pole emerges.
| [
{
"created": "Sat, 27 Jan 2007 21:47:39 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Gergely",
"László Á.",
""
],
[
"Perjés",
"Zoltán I.",
""
],
[
"Vasúth",
"Mátyás",
""
]
] | The true- and eccentric-anomaly parametrizations of the Kepler motion are generalized to quasiperiodic orbits by considering perturbations of the radial part of kinetic energy as a series in the negative powers of the orbital radius. A toolbox of methods for averaging observables in terms of the energy $E$ and angular momentum $L$ is developed. A broad range of systems governed by the generic Brumberg force, as well as recent applications of the theory of gravitational radiation involve integrals over a period of motion. These integrals are evaluated by using the residue theorem. It is shown that the pole of the integrand is located in the origin and that under certain circumstances an additional pole emerges. |
gr-qc/0106010 | Louis Scheffer | Louis K. Scheffer | Support for a prosaic explanation for the anomalous acceleration of
Pioneer 10 and 11 | 3 pages, revtex4 | null | null | null | gr-qc | null | Anderson, et al., find the measured trajectories of Pioneer 10 and 11
spacecraft deviate from the trajectories computed from known forces acting on
them. This unmodelled acceleration can be accounted for by non-isotropic
radiation of spacecraft heat. This explanation was first proposed by Murphy,
but Anderson, et al. felt it could not explain the observed effect. This paper
includes new calculations on the expected magnitude of this effect, based on
the relative emissivities of the different sides of the spacecraft, as
estimated from the known spacecraft construction. The calculations indicate the
proposed effect can account for most, if not all, of the unmodelled
acceleration.
| [
{
"created": "Mon, 4 Jun 2001 19:43:20 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Scheffer",
"Louis K.",
""
]
] | Anderson, et al., find the measured trajectories of Pioneer 10 and 11 spacecraft deviate from the trajectories computed from known forces acting on them. This unmodelled acceleration can be accounted for by non-isotropic radiation of spacecraft heat. This explanation was first proposed by Murphy, but Anderson, et al. felt it could not explain the observed effect. This paper includes new calculations on the expected magnitude of this effect, based on the relative emissivities of the different sides of the spacecraft, as estimated from the known spacecraft construction. The calculations indicate the proposed effect can account for most, if not all, of the unmodelled acceleration. |
gr-qc/9708033 | Alberto Vecchio | A. Vecchio, B. Bertotti and L. Iess | Coalescing binaries and Doppler experiments | 5 pages, LaTeX, one postscript figure included. Talk given at the
"Second Amaldi Conference on Gravitational Waves" (CERN, 1-4 July 1997). To
be published in the Proceedings (World Scientific, Singapore), eds. E. Coccia
et al | null | null | null | gr-qc | null | We discuss the sensitivity of the CASSINI experiments to gravitational waves
emitted by the in-spiral of compact binaries. We show that the maximum distance
reachable by the instrument is $\sim 100$ Mpc. In particular, CASSINI can
detect massive black hole binaries with chirp mass $\simgt 10^6 \Ms$ in the
Virgo Cluster with signal-to-noise ratio between 5 and 30 and possible compact
objects of mass $\simgt 30 \Ms$ orbiting the massive black hole that our
Galactic Centre is likely to harbour.
| [
{
"created": "Sat, 16 Aug 1997 09:17:10 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Vecchio",
"A.",
""
],
[
"Bertotti",
"B.",
""
],
[
"Iess",
"L.",
""
]
] | We discuss the sensitivity of the CASSINI experiments to gravitational waves emitted by the in-spiral of compact binaries. We show that the maximum distance reachable by the instrument is $\sim 100$ Mpc. In particular, CASSINI can detect massive black hole binaries with chirp mass $\simgt 10^6 \Ms$ in the Virgo Cluster with signal-to-noise ratio between 5 and 30 and possible compact objects of mass $\simgt 30 \Ms$ orbiting the massive black hole that our Galactic Centre is likely to harbour. |
2203.07708 | Chiranjeeb Singha | Chiranjeeb Singha, Sumanta Chakraborty, Naresh Dadhich | Strong cosmic censorship conjecture for a charged BTZ black hole | 20 pages, 6 figures | JHEP06(2022)028 | 10.1007/JHEP06(2022)028 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The strong cosmic censorship conjecture, whose validation asserts the
deterministic nature of general relativity, has been studied for charged BTZ
black holes in three dimensional general relativity, as well as for Nth order
pure Lovelock gravity in d=2N+1 spacetime dimensions. Through both analytical
and numerical routes, we have computed the ratio of the imaginary part of the
quasi-normal mode frequencies with the surface gravity at the Cauchy horizon.
The lowest of which corresponds to the key parameter associated with violation
of strong cosmic censorship conjecture. Our results demonstrate that this
parameter is always less than the critical value $(1/2)$, thereby respecting
the strong cosmic censorship conjecture. This is in complete contrast to the
four or, higher dimensional black holes, as well as for rotating BTZ black
hole, where the violation of strong cosmic censorship conjecture exists.
Implications and possible connection with the stability of the photon orbits
have been discussed.
| [
{
"created": "Tue, 15 Mar 2022 07:56:24 GMT",
"version": "v1"
},
{
"created": "Mon, 21 Mar 2022 10:24:52 GMT",
"version": "v2"
},
{
"created": "Tue, 7 Jun 2022 06:06:58 GMT",
"version": "v3"
}
] | 2022-06-08 | [
[
"Singha",
"Chiranjeeb",
""
],
[
"Chakraborty",
"Sumanta",
""
],
[
"Dadhich",
"Naresh",
""
]
] | The strong cosmic censorship conjecture, whose validation asserts the deterministic nature of general relativity, has been studied for charged BTZ black holes in three dimensional general relativity, as well as for Nth order pure Lovelock gravity in d=2N+1 spacetime dimensions. Through both analytical and numerical routes, we have computed the ratio of the imaginary part of the quasi-normal mode frequencies with the surface gravity at the Cauchy horizon. The lowest of which corresponds to the key parameter associated with violation of strong cosmic censorship conjecture. Our results demonstrate that this parameter is always less than the critical value $(1/2)$, thereby respecting the strong cosmic censorship conjecture. This is in complete contrast to the four or, higher dimensional black holes, as well as for rotating BTZ black hole, where the violation of strong cosmic censorship conjecture exists. Implications and possible connection with the stability of the photon orbits have been discussed. |
0712.0464 | Valentin Kuzmichev | V. E. Kuzmichev, V. V. Kuzmichev (Bogolyubov Institute for Theoretical
Physics) | The Big Bang quantum cosmology: The matter-energy production epoch | 16 pages, v.2 a few misprints are corrected and small additional
explanations are provided | Acta Phys.Polon.B39:979,2008 | null | null | gr-qc astro-ph | null | The exactly solvable quantum model of the homogeneous, isotropic and closed
universe in the matter-energy production epoch is considered. It is assumed
that the universe is originally filled with a uniform scalar field and a
perfect fluid which defines a reference frame. The stationary state spectrum
and the wave functions of the quantum universe are calculated. In this model
the matter-energy in the universe has a component in the form of a condensate
of massive zero-momentum excitation quanta of oscillations of primordial scalar
field. The mean value of the scale factor of the universe in a given state is
connected with the mass of a condensate by a linear relation. The nucleation
rate of the universe from the initial cosmological singularity point is
calculated. It is demonstrated that the process of nucleation of the universe
can have an exponential (explosive) nature. The evolution of the universe is
described as transitions with non-zero probabilities between the states of the
universe with different masses of a condensate.
| [
{
"created": "Tue, 4 Dec 2007 09:36:50 GMT",
"version": "v1"
},
{
"created": "Wed, 30 Apr 2008 08:59:57 GMT",
"version": "v2"
}
] | 2011-07-19 | [
[
"Kuzmichev",
"V. E.",
"",
"Bogolyubov Institute for Theoretical\n Physics"
],
[
"Kuzmichev",
"V. V.",
"",
"Bogolyubov Institute for Theoretical\n Physics"
]
] | The exactly solvable quantum model of the homogeneous, isotropic and closed universe in the matter-energy production epoch is considered. It is assumed that the universe is originally filled with a uniform scalar field and a perfect fluid which defines a reference frame. The stationary state spectrum and the wave functions of the quantum universe are calculated. In this model the matter-energy in the universe has a component in the form of a condensate of massive zero-momentum excitation quanta of oscillations of primordial scalar field. The mean value of the scale factor of the universe in a given state is connected with the mass of a condensate by a linear relation. The nucleation rate of the universe from the initial cosmological singularity point is calculated. It is demonstrated that the process of nucleation of the universe can have an exponential (explosive) nature. The evolution of the universe is described as transitions with non-zero probabilities between the states of the universe with different masses of a condensate. |
gr-qc/0604074 | Rajeev Bhalerao | B. Ram and J. Shirley | The quantum black hole in 2+1 dimensions | 5 pages, no figs | null | null | null | gr-qc astro-ph quant-ph | null | In this paper we investigate the quantum nature of a 2+1 dimensional black
hole using the method [arXiv: gr-qc/0504030] which earlier revealed the quantum
nature of a black hole in 3+1 dimensions.
| [
{
"created": "Tue, 18 Apr 2006 05:19:39 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Ram",
"B.",
""
],
[
"Shirley",
"J.",
""
]
] | In this paper we investigate the quantum nature of a 2+1 dimensional black hole using the method [arXiv: gr-qc/0504030] which earlier revealed the quantum nature of a black hole in 3+1 dimensions. |
1604.07639 | Yoo Geun Song | Yoogeun Song and Seok Jae Park | The Influence of the Shear on the Gravitational Waves in the Early
Anisotropic Universe | arXiv admin note: text overlap with arXiv:1103.0300 by other authors | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the singularity of the congruences for both timelike and null
geodesic curves using the expansion of the early anisotropic Bianchi type I
Universe. In this paper, we concentrate on the influence of the shear of the
timelike and null geodesic congruences in the early Universe. Under some
natural conditions, we derive the Raychaudhuri type equation for the expansion
and the shear-related equations. Recently, scientists working on the LIGO
(Laser Interferometer Gravitational-Wave Observatory) have shown many
possibilities to observing the anisotropy of the primordial gravitational wave
background radiation. We deduce the evolution equation for the shear that may
be responsible for those observational results.
| [
{
"created": "Mon, 25 Apr 2016 07:28:24 GMT",
"version": "v1"
}
] | 2016-04-27 | [
[
"Song",
"Yoogeun",
""
],
[
"Park",
"Seok Jae",
""
]
] | We study the singularity of the congruences for both timelike and null geodesic curves using the expansion of the early anisotropic Bianchi type I Universe. In this paper, we concentrate on the influence of the shear of the timelike and null geodesic congruences in the early Universe. Under some natural conditions, we derive the Raychaudhuri type equation for the expansion and the shear-related equations. Recently, scientists working on the LIGO (Laser Interferometer Gravitational-Wave Observatory) have shown many possibilities to observing the anisotropy of the primordial gravitational wave background radiation. We deduce the evolution equation for the shear that may be responsible for those observational results. |
1308.4976 | Suprit Singh | Suprit Singh, Sujoy Kumar Modak and T. Padmanabhan | Evolution of quantum field, particle content and classicality in the
three stage universe | Version 2. Added section IV C. Published in Physical Review D | Phys. Rev. D 88, 125020 (2013) | 10.1103/PhysRevD.88.125020 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the evolution of a quantum scalar field in a toy universe which has
three stages of evolution, viz., (i) an early (inflationary) de Sitter phase
(ii) radiation dominated phase and (iii) late-time (cosmological constant
dominated) de Sitter phase. Using Schr\"odinger picture, the scalar field
equations are solved separately for the three stages and matched at the
transition points. The boundary conditions are chosen so that field modes in
the early de Sitter evolves from Bunch-Davies vacuum state. We determine the
(time-dependent) particle content of this quantum state for the entire
evolution of the universe and describe the various features both numerically
and analytically. We also describe the quantum to classical transition in terms
of a {\it classicality parameter} which tracks the particle creation and its
effect on phase space correlation of the quantum field.
| [
{
"created": "Thu, 22 Aug 2013 20:00:06 GMT",
"version": "v1"
},
{
"created": "Wed, 11 Dec 2013 09:05:47 GMT",
"version": "v2"
}
] | 2013-12-12 | [
[
"Singh",
"Suprit",
""
],
[
"Modak",
"Sujoy Kumar",
""
],
[
"Padmanabhan",
"T.",
""
]
] | We study the evolution of a quantum scalar field in a toy universe which has three stages of evolution, viz., (i) an early (inflationary) de Sitter phase (ii) radiation dominated phase and (iii) late-time (cosmological constant dominated) de Sitter phase. Using Schr\"odinger picture, the scalar field equations are solved separately for the three stages and matched at the transition points. The boundary conditions are chosen so that field modes in the early de Sitter evolves from Bunch-Davies vacuum state. We determine the (time-dependent) particle content of this quantum state for the entire evolution of the universe and describe the various features both numerically and analytically. We also describe the quantum to classical transition in terms of a {\it classicality parameter} which tracks the particle creation and its effect on phase space correlation of the quantum field. |
gr-qc/0701063 | Salvatore Antoci | S. Antoci, D.-E. Liebscher, L. Mihich | Electrostatics and confinement in Einstein's unified field theory | 4 pages, talk given at MG11, Berlin, July 2006 | null | 10.1142/9789812834300_0122 | null | gr-qc hep-th | null | A way for appending sources at the right-hand sides of the field equations of
Einstein's unified field theory is recalled. Two exact solutions endowed with
point sources in equilibrium are shown, and their physical meaning is
discussed.
| [
{
"created": "Thu, 11 Jan 2007 15:37:59 GMT",
"version": "v1"
}
] | 2016-11-15 | [
[
"Antoci",
"S.",
""
],
[
"Liebscher",
"D. -E.",
""
],
[
"Mihich",
"L.",
""
]
] | A way for appending sources at the right-hand sides of the field equations of Einstein's unified field theory is recalled. Two exact solutions endowed with point sources in equilibrium are shown, and their physical meaning is discussed. |
1502.00073 | Christos Tzounis | Shohreh Abdolrahimi, Robert B. Mann and Christos Tzounis | Distorted Local Shadows | 17 pages 18 figures | Phys. Rev. D 91, 084052 (2015) | 10.1103/PhysRevD.91.084052 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We introduce the notion of a local shadow for a black hole and determine its
shape for the particular case of a distorted Schwarzschild black hole.
Considering the lowest-order even and odd multiple moments, we compute the
relation between the deformations of the shadow of a Schwarzschild black hole
and the distortion multiple moments. For the range of values of multiple
moments that we consider, the horizon is deformed much less than its
corresponding shadow, suggesting the horizon is more `rigid'. Quite
unexpectedly we find that a prolate distortion of the horizon gives rise to an
oblate distortion of the shadow, and vice-versa.
| [
{
"created": "Sat, 31 Jan 2015 06:05:00 GMT",
"version": "v1"
},
{
"created": "Mon, 9 Feb 2015 17:36:22 GMT",
"version": "v2"
},
{
"created": "Wed, 11 Feb 2015 01:51:24 GMT",
"version": "v3"
},
{
"created": "Wed, 22 Apr 2015 00:57:24 GMT",
"version": "v4"
}
] | 2015-05-11 | [
[
"Abdolrahimi",
"Shohreh",
""
],
[
"Mann",
"Robert B.",
""
],
[
"Tzounis",
"Christos",
""
]
] | We introduce the notion of a local shadow for a black hole and determine its shape for the particular case of a distorted Schwarzschild black hole. Considering the lowest-order even and odd multiple moments, we compute the relation between the deformations of the shadow of a Schwarzschild black hole and the distortion multiple moments. For the range of values of multiple moments that we consider, the horizon is deformed much less than its corresponding shadow, suggesting the horizon is more `rigid'. Quite unexpectedly we find that a prolate distortion of the horizon gives rise to an oblate distortion of the shadow, and vice-versa. |
gr-qc/9804043 | Walentin D. Gladush | V.D. Gladush and R.A. Konoplya | Split structures in general relativity and the Kaluza-Klein theories | 30 pages, RevTeX, aps.sty, some additions and corrections, new
references added | J.Math.Phys.40:955-979,1999 | 10.1063/1.532697 | null | gr-qc math.DG | null | We construct a general approach to decomposition of the tangent bundle of
pseudo-Riemannian manifolds into direct sums of subbundles, and the associated
decomposition of geometric objects. An invariant structure {\cal H}^r defined
as a set of r projection operators is used to induce decomposition of the
geometric objects into those of the corresponding subbundles. We define the
main geometric objects characterizing decomposition. Invariant non-holonomic
generalizations of the Gauss-Codazzi-Ricci's relations have been obtained. All
the known types of decomposition (used in the theory of frames of reference, in
the Hamiltonian formulation for gravity, in the Cauchy problem, in the theory
of stationary spaces, and so on) follow from the present work as special cases
when fixing a basis and dimensions of subbundles, and parameterization of a
basis of decomposition. Various methods of decomposition have been applied here
for the Unified Multidimensional Kaluza-Klein Theory and for relativistic
configurations of a perfect fluid. Discussing an invariant form of the
equations of motion we have found the invariant equilibrium conditions and
their 3+1 decomposed form. The formulation of the conservation law for the curl
has been obtained in the invariant form.
| [
{
"created": "Mon, 20 Apr 1998 12:29:56 GMT",
"version": "v1"
},
{
"created": "Mon, 2 Nov 1998 15:32:29 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Gladush",
"V. D.",
""
],
[
"Konoplya",
"R. A.",
""
]
] | We construct a general approach to decomposition of the tangent bundle of pseudo-Riemannian manifolds into direct sums of subbundles, and the associated decomposition of geometric objects. An invariant structure {\cal H}^r defined as a set of r projection operators is used to induce decomposition of the geometric objects into those of the corresponding subbundles. We define the main geometric objects characterizing decomposition. Invariant non-holonomic generalizations of the Gauss-Codazzi-Ricci's relations have been obtained. All the known types of decomposition (used in the theory of frames of reference, in the Hamiltonian formulation for gravity, in the Cauchy problem, in the theory of stationary spaces, and so on) follow from the present work as special cases when fixing a basis and dimensions of subbundles, and parameterization of a basis of decomposition. Various methods of decomposition have been applied here for the Unified Multidimensional Kaluza-Klein Theory and for relativistic configurations of a perfect fluid. Discussing an invariant form of the equations of motion we have found the invariant equilibrium conditions and their 3+1 decomposed form. The formulation of the conservation law for the curl has been obtained in the invariant form. |
1905.06206 | Edward Anderson | Edward Anderson | A Local Resolution of the Problem of Time. II. Configurational
Relationalism via a generalization of Group Averaging | 28 pages, including 8 figures. v4 has minor presentational upgrades | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this article, we consider a second Problem of Time Facet. This started
life as Wheeler's Thin Sandwich Problem, within the narrow context of 1)
GR-as-Geometrodynamics, in particular its momentum constraint. 2) A Lagrangian
variables level treatment. Conceiving in terms of Barbour's Best Matching is a
freeing from 1), now in the context of first-class linear constraints.
Conceiving in terms of the underlying Background Independence aspect - the
titular Configurational Relationalism - serves moreover to remove 2) as well.
This is implemented by the $G$-act, $G$-all method. I.e. given an object $O$
that is not $G$-invariant, we act on it with $G$ and then apply an operation
involving the whole group. This has the effect of double-cancelling the
introduction of our group action, thus yielding a $G$-independent version of
$O$. A first example of whole-group operation is group averaging. This is a
valuable prototype by its familiarity to a large proportion of Mathematics and
Physics majors through featuring in elementary Group Theory and Representation
Theory courses (and which can be traced back to Cauchy). In particular, this is
much more familiar than Thin Sandwiches or Best Matching! Secondly,
extremization over the group, of which Best Matching, and taking infs or sups
over the group, are examples. Some further significant examples of this method
in modern geometry and topology include those of Kendall, Younes, Hausdorff and
Gromov. In this way, we populate this approach with examples well beyond the
usual GR literature's by DeWitt, Barbour and Fischer (which we also outline).
| [
{
"created": "Wed, 15 May 2019 14:23:33 GMT",
"version": "v1"
},
{
"created": "Sun, 9 Jun 2019 14:18:18 GMT",
"version": "v2"
},
{
"created": "Mon, 8 Jul 2019 16:55:05 GMT",
"version": "v3"
},
{
"created": "Thu, 24 Oct 2019 15:38:30 GMT",
"version": "v4"
}
] | 2019-10-25 | [
[
"Anderson",
"Edward",
""
]
] | In this article, we consider a second Problem of Time Facet. This started life as Wheeler's Thin Sandwich Problem, within the narrow context of 1) GR-as-Geometrodynamics, in particular its momentum constraint. 2) A Lagrangian variables level treatment. Conceiving in terms of Barbour's Best Matching is a freeing from 1), now in the context of first-class linear constraints. Conceiving in terms of the underlying Background Independence aspect - the titular Configurational Relationalism - serves moreover to remove 2) as well. This is implemented by the $G$-act, $G$-all method. I.e. given an object $O$ that is not $G$-invariant, we act on it with $G$ and then apply an operation involving the whole group. This has the effect of double-cancelling the introduction of our group action, thus yielding a $G$-independent version of $O$. A first example of whole-group operation is group averaging. This is a valuable prototype by its familiarity to a large proportion of Mathematics and Physics majors through featuring in elementary Group Theory and Representation Theory courses (and which can be traced back to Cauchy). In particular, this is much more familiar than Thin Sandwiches or Best Matching! Secondly, extremization over the group, of which Best Matching, and taking infs or sups over the group, are examples. Some further significant examples of this method in modern geometry and topology include those of Kendall, Younes, Hausdorff and Gromov. In this way, we populate this approach with examples well beyond the usual GR literature's by DeWitt, Barbour and Fischer (which we also outline). |
1811.04061 | Kuantay Boshkayev | Kuantay Boshkayev and Daniele Malafarina | A model for a dark matter core at the galactic center | 9 pages, 9 figures | null | 10.1093/mnras/stz219 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a toy model for the supermassive compact object at the galactic
center that does not require the presence of a black hole. We assume a matter
distribution of weakly interacting particles with a density profile inferred
from dark matter profiles in the outer regions. We show that rotation curves
close to the center of the Milky Way galaxy can be explained within this model.
We also show that the motion of test particles (stars) at distances of the
order of 100 astronomical units can not be distinguished from the motion of
corresponding particles in the Schwarzschild geometry. However, differences
arise at shorter distances, suggesting that it could be possible to
observationally test the validity of the model in the near future.
| [
{
"created": "Fri, 9 Nov 2018 18:43:35 GMT",
"version": "v1"
},
{
"created": "Wed, 19 Dec 2018 14:16:13 GMT",
"version": "v2"
}
] | 2019-05-20 | [
[
"Boshkayev",
"Kuantay",
""
],
[
"Malafarina",
"Daniele",
""
]
] | We consider a toy model for the supermassive compact object at the galactic center that does not require the presence of a black hole. We assume a matter distribution of weakly interacting particles with a density profile inferred from dark matter profiles in the outer regions. We show that rotation curves close to the center of the Milky Way galaxy can be explained within this model. We also show that the motion of test particles (stars) at distances of the order of 100 astronomical units can not be distinguished from the motion of corresponding particles in the Schwarzschild geometry. However, differences arise at shorter distances, suggesting that it could be possible to observationally test the validity of the model in the near future. |
gr-qc/0407098 | Etera R. Livine | Florian Girelli, Etera R. Livine | Special Relativity as a non commutative geometry: Lessons for Deformed
Special Relativity | 24 pages, RevTeX4 | null | null | null | gr-qc hep-th | null | Deformed Special Relativity (DSR) is obtained by imposing a maximal energy to
Special Relativity and deforming the Lorentz symmetry (more exactly the
Poincar\'e symmetry) to accommodate this requirement. One can apply the same
procedure deforming the Galilean symmetry in order to impose a maximal speed
(the speed of light). This leads to a non-commutative space structure, to the
expected deformations of composition of speed and conservation of
energy-momentum. In doing so, one runs into most of the ambiguities that one
stumbles onto in the DSR context. However, this time, Special Relativity is
there to tell us what is the underlying physics, in such a way that we can
understand and interpret these ambiguities. We use these insights to comment on
the physics of DSR.
| [
{
"created": "Mon, 26 Jul 2004 18:58:31 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Girelli",
"Florian",
""
],
[
"Livine",
"Etera R.",
""
]
] | Deformed Special Relativity (DSR) is obtained by imposing a maximal energy to Special Relativity and deforming the Lorentz symmetry (more exactly the Poincar\'e symmetry) to accommodate this requirement. One can apply the same procedure deforming the Galilean symmetry in order to impose a maximal speed (the speed of light). This leads to a non-commutative space structure, to the expected deformations of composition of speed and conservation of energy-momentum. In doing so, one runs into most of the ambiguities that one stumbles onto in the DSR context. However, this time, Special Relativity is there to tell us what is the underlying physics, in such a way that we can understand and interpret these ambiguities. We use these insights to comment on the physics of DSR. |
1509.02854 | Peter Wolf | Peter Wolf and Luc Blanchet | Analysis of Sun/Moon Gravitational Redshift tests with the STE-QUEST
Space Mission | 17 pages, 3 figures | Classical and Quantum Gravity, 2016, 33, 035012 | 10.1088/0264-9381/33/3/035012 | null | gr-qc physics.space-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The STE-QUEST space mission will perform tests of the gravitational redshift
in the field of the Sun and the Moon to high precision by frequency comparisons
of clocks attached to the ground and separated by intercontinental distances.
In the absence of Einstein equivalence principle (EP) violation, the redshift
is zero up to small tidal corrections as the Earth is freely falling in the
field of the Sun and Moon. Such tests are thus null tests, allowing to bound
possible violations of the EP. Here we analyze the Sun/Moon redshift tests
using a generic EP violating theoretical framework, with clocks minimally
modelled as two-level atoms. We present a complete derivation of the redshift
(including both GR and non-GR terms) in a realistic experiment such as the one
envisaged for STE-QUEST. We point out and correct an error in previous
formalisms linked to the atom's recoil not being properly taken into account.
| [
{
"created": "Wed, 9 Sep 2015 17:14:20 GMT",
"version": "v1"
},
{
"created": "Fri, 20 Nov 2015 09:13:10 GMT",
"version": "v2"
}
] | 2016-01-27 | [
[
"Wolf",
"Peter",
""
],
[
"Blanchet",
"Luc",
""
]
] | The STE-QUEST space mission will perform tests of the gravitational redshift in the field of the Sun and the Moon to high precision by frequency comparisons of clocks attached to the ground and separated by intercontinental distances. In the absence of Einstein equivalence principle (EP) violation, the redshift is zero up to small tidal corrections as the Earth is freely falling in the field of the Sun and Moon. Such tests are thus null tests, allowing to bound possible violations of the EP. Here we analyze the Sun/Moon redshift tests using a generic EP violating theoretical framework, with clocks minimally modelled as two-level atoms. We present a complete derivation of the redshift (including both GR and non-GR terms) in a realistic experiment such as the one envisaged for STE-QUEST. We point out and correct an error in previous formalisms linked to the atom's recoil not being properly taken into account. |
gr-qc/0004055 | Mauricio Cataldo Monsalves | M. Cataldo and S. del Campo | Comment on "Viscous cosmology in the Kasner metric" | 2 pages, Latex, accepted in Phys. Rev. D | Phys.Rev. D61 (2000) 128301 | 10.1103/PhysRevD.61.128301 | null | gr-qc | null | We show in this comment that in an anisotropic Bianchi type I model of the
Kasner form, it is not possible to describe the growth of entropy, if we want
to keep the thermodynamics together with the dominant energy conditions. This
consequence disagrees with the results obtained by Brevik and Pettersen [Phys.
Rev. D 56, 3322 (1997)].
| [
{
"created": "Mon, 17 Apr 2000 16:03:43 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Cataldo",
"M.",
""
],
[
"del Campo",
"S.",
""
]
] | We show in this comment that in an anisotropic Bianchi type I model of the Kasner form, it is not possible to describe the growth of entropy, if we want to keep the thermodynamics together with the dominant energy conditions. This consequence disagrees with the results obtained by Brevik and Pettersen [Phys. Rev. D 56, 3322 (1997)]. |
1506.02012 | Hendrik Jennen | H. Jennen, J. G. Pereira | Dark energy as a kinematic effect | 6 pages, conclusions updated, references added | Phys. Dark Univ. 11 (2016) 49-53 | 10.1016/j.dark.2015.11.002 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a generalization of teleparallel gravity that is consistent with
local spacetime kinematics regulated by the de Sitter group $SO(1,4)$. The
mathematical structure of teleparallel gravity is shown to be given by a
nonlinear Riemann-Cartan geometry without curvature, which inspires us to build
the generalization on top of a de Sitter-Cartan geometry with a cosmological
function. The cosmological function is given its own dynamics and naturally
emerges nonminimally coupled to the gravitational field in a manner akin to
teleparallel dark energy models or scalar-tensor theories in general
relativity. New in the theory here presented, the cosmological function gives
rise to a kinematic contribution in the deviation equation for the world lines
of adjacent free-falling particles. While having its own dynamics, dark energy
manifests itself in the local kinematics of spacetime.
| [
{
"created": "Fri, 5 Jun 2015 19:17:06 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Dec 2015 11:41:59 GMT",
"version": "v2"
}
] | 2015-12-04 | [
[
"Jennen",
"H.",
""
],
[
"Pereira",
"J. G.",
""
]
] | We present a generalization of teleparallel gravity that is consistent with local spacetime kinematics regulated by the de Sitter group $SO(1,4)$. The mathematical structure of teleparallel gravity is shown to be given by a nonlinear Riemann-Cartan geometry without curvature, which inspires us to build the generalization on top of a de Sitter-Cartan geometry with a cosmological function. The cosmological function is given its own dynamics and naturally emerges nonminimally coupled to the gravitational field in a manner akin to teleparallel dark energy models or scalar-tensor theories in general relativity. New in the theory here presented, the cosmological function gives rise to a kinematic contribution in the deviation equation for the world lines of adjacent free-falling particles. While having its own dynamics, dark energy manifests itself in the local kinematics of spacetime. |
gr-qc/9402012 | Friedrich Wilhelm Hehl | F.W. Hehl, J.D. McCrea, E.W. Mielke, Y. Ne'eman | Metric-Affine Gauge Theory of Gravity: Field Equations, Noether
Identities, World Spinors, and Breaking of Dilation Invariance | 197 pages | Phys.Rept.258:1-171,1995 | 10.1016/0370-1573(94)00111-F | Tel-Aviv University preprint N192 (1994) | gr-qc hep-th | null | In Einstein's gravitational theory, the spacetime is Riemannian, that is, it
has vanishing torsion and vanishing nonmetricity (covariant derivative of the
metric). In the gauging of the general affine group ${A}(4,R)$ and of its
subgroup ${GL}(4,R)$ in four dimensions, energy--momentum and hypermomentum
currents of matter are canonically coupled to the one--form basis and to the
connection of a metric--affine spacetime with nonvanishing torsion and
nonmetricity, respectively. Fermionic matter can be described in this framework
by half--integer representations of the $\overline{SL}(4,R)$ covering subgroup.
--- We set up a (first--order) Lagrangian formalism and build up the
corresponding Noether machinery. For an arbitrary gauge Lagrangian, the three
gauge field equations come out in a suggestive Yang-Mills like form. The
conservation--type differential identities for energy--momentum and
hypermomentum and the corresponding complexes and superpotentials are derived.
Limiting cases such as the Einstein--Cartan theory are discussed. In particular
we show, how the ${A}(4,R)$ may ``break down'' to the Poincar\'e (inhomogeneous
Lorentz) group. In this context, we present explicit models for a symmetry
breakdown in the cases of the Weyl (or homothetic) group, the ${SL}(4,R)$, or
the ${GL}(4,R)$.
| [
{
"created": "Fri, 4 Feb 1994 16:03:04 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Hehl",
"F. W.",
""
],
[
"McCrea",
"J. D.",
""
],
[
"Mielke",
"E. W.",
""
],
[
"Ne'eman",
"Y.",
""
]
] | In Einstein's gravitational theory, the spacetime is Riemannian, that is, it has vanishing torsion and vanishing nonmetricity (covariant derivative of the metric). In the gauging of the general affine group ${A}(4,R)$ and of its subgroup ${GL}(4,R)$ in four dimensions, energy--momentum and hypermomentum currents of matter are canonically coupled to the one--form basis and to the connection of a metric--affine spacetime with nonvanishing torsion and nonmetricity, respectively. Fermionic matter can be described in this framework by half--integer representations of the $\overline{SL}(4,R)$ covering subgroup. --- We set up a (first--order) Lagrangian formalism and build up the corresponding Noether machinery. For an arbitrary gauge Lagrangian, the three gauge field equations come out in a suggestive Yang-Mills like form. The conservation--type differential identities for energy--momentum and hypermomentum and the corresponding complexes and superpotentials are derived. Limiting cases such as the Einstein--Cartan theory are discussed. In particular we show, how the ${A}(4,R)$ may ``break down'' to the Poincar\'e (inhomogeneous Lorentz) group. In this context, we present explicit models for a symmetry breakdown in the cases of the Weyl (or homothetic) group, the ${SL}(4,R)$, or the ${GL}(4,R)$. |
1411.0833 | Meng-Sen Ma | Meng-Sen Ma, Ren Zhao | Corrected form of the first law of thermodynamics for regular black
holes | 11 pages, no figures, to be published in Classical and Quantum
Gravity | null | 10.1088/0264-9381/31/24/245014 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show by explicit computations that there is a superficial inconsistency
between the conventional first law of black hole thermodynamics and
Bekenstein-Hawking area law for three types of regular black holes. The
corrected form of the first law for these regular black holes is given. The
derivation relies on the general structure of the energy-momentum tensor of the
matter fields. When the black hole mass parameter $M$ is included in the
energy-momentum tensor, the conventional form of the first law should be
modified with an extra factor. In this case, the black hole mass $M$ can no
longer be considered as the internal energy of the regular black holes.
| [
{
"created": "Tue, 4 Nov 2014 09:31:21 GMT",
"version": "v1"
}
] | 2015-06-23 | [
[
"Ma",
"Meng-Sen",
""
],
[
"Zhao",
"Ren",
""
]
] | We show by explicit computations that there is a superficial inconsistency between the conventional first law of black hole thermodynamics and Bekenstein-Hawking area law for three types of regular black holes. The corrected form of the first law for these regular black holes is given. The derivation relies on the general structure of the energy-momentum tensor of the matter fields. When the black hole mass parameter $M$ is included in the energy-momentum tensor, the conventional form of the first law should be modified with an extra factor. In this case, the black hole mass $M$ can no longer be considered as the internal energy of the regular black holes. |
1805.05664 | Rituparno Goswami | Sayuri Singh, Rituparno Goswami, Sunil D. Maharaj | Conformal Symmetries of Locally Rotationally Symmetric Spacetimes | 6 pages, Revtex4 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we investigate conformal symmetries in Locally Rotationally
Symmetric (LRS) spacetimes using a semitetrad covariant formalism. We
demonstrate that a general LRS spacetime which rotates and spatially twists
simultaneously has an inherent homothetic symmetry in the plane spanned by the
fluid flow lines and the preferred spatial direction. We discuss the nature and
consequence of this homothetic symmetry showing that a null Killing horizon
arises when the heat flux has an extremal value. We also consider the special
case of a perfect fluid and the restriction on the conformal geometry.
| [
{
"created": "Tue, 15 May 2018 09:35:09 GMT",
"version": "v1"
}
] | 2018-05-16 | [
[
"Singh",
"Sayuri",
""
],
[
"Goswami",
"Rituparno",
""
],
[
"Maharaj",
"Sunil D.",
""
]
] | In this paper we investigate conformal symmetries in Locally Rotationally Symmetric (LRS) spacetimes using a semitetrad covariant formalism. We demonstrate that a general LRS spacetime which rotates and spatially twists simultaneously has an inherent homothetic symmetry in the plane spanned by the fluid flow lines and the preferred spatial direction. We discuss the nature and consequence of this homothetic symmetry showing that a null Killing horizon arises when the heat flux has an extremal value. We also consider the special case of a perfect fluid and the restriction on the conformal geometry. |
gr-qc/0111058 | Carlos Augusto Romero Filho | F. Dahia and C. Romero | The embedding of the spacetime in five-dimensional spaces with arbitrary
non-degenerate Ricci tensor | null | J.Math.Phys. 43 (2002) 3097-3106 | 10.1063/1.1473680 | null | gr-qc | null | We discuss and prove a theorem which asserts that any n-dimensional
semi-Riemannian manifold can be locally embedded in a (n+1)-dimensional space
with a non-degenerate Ricci tensor which is equal, up to a local analytic
diffeomorphism, to the Ricci tensor of an arbitrary specified space. This may
be regarded as a further extension of the Campbell-Magaard theorem. We
highlight the significance of embedding theorems of increasing degrees of
generality in the context of higher dimensional spacetimes theories and
illustrate the new theorem by establishing the embedding of a general class of
Ricci-flat spacetimes.
| [
{
"created": "Mon, 19 Nov 2001 01:50:02 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Dahia",
"F.",
""
],
[
"Romero",
"C.",
""
]
] | We discuss and prove a theorem which asserts that any n-dimensional semi-Riemannian manifold can be locally embedded in a (n+1)-dimensional space with a non-degenerate Ricci tensor which is equal, up to a local analytic diffeomorphism, to the Ricci tensor of an arbitrary specified space. This may be regarded as a further extension of the Campbell-Magaard theorem. We highlight the significance of embedding theorems of increasing degrees of generality in the context of higher dimensional spacetimes theories and illustrate the new theorem by establishing the embedding of a general class of Ricci-flat spacetimes. |
gr-qc/9903013 | Alicia M. Sintes | Alicia M. Sintes and Bernard F. Schutz | Removing non-stationary, non-harmonic external interference from
gravitational wave interferometer data | 14 pages, 5 figures, Revtex, psfig | Phys.Rev.D60:062001,1999 | 10.1103/PhysRevD.60.062001 | null | gr-qc | null | We describe a procedure to identify and remove a class of non-stationary and
non-harmonic interference lines from gravitational wave interferometer data.
These lines appear to be associated with the external electricity main
supply, but their amplitudes are non-stationary and they do not appear at
harmonics of the fundamental supply frequency. We find an empirical model able
to represent coherently all the non-harmonic lines we have found in the power
spectrum, in terms of an assumed reference signal of the primary supply input
signal. If this signal is not available then it can be reconstructed from the
same data by making use of the coherent line removal algorithm that we have
described elsewhere. All these lines are broadened by frequency changes of the
supply signal, and they corrupt significant frequency ranges of the power
spectrum. The physical process that generates this interference is so far
unknown, but it is highly non-linear and non-stationary. Using our model, we
cancel the interference in the time domain by an adaptive procedure that should
work regardless of the source of the primary interference. We have applied the
method to laser interferometer data from the Glasgow prototype detector, where
all the features we describe in this paper were observed. The algorithm has
been tuned in such a way that the entire series of wide lines corresponding to
the electrical interference are removed, leaving the spectrum clean enough to
detect signals previously masked by them. Single-line signals buried in the
interference can be recovered with at least 75 % of their original signal
amplitude.
| [
{
"created": "Wed, 3 Mar 1999 08:39:34 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Sintes",
"Alicia M.",
""
],
[
"Schutz",
"Bernard F.",
""
]
] | We describe a procedure to identify and remove a class of non-stationary and non-harmonic interference lines from gravitational wave interferometer data. These lines appear to be associated with the external electricity main supply, but their amplitudes are non-stationary and they do not appear at harmonics of the fundamental supply frequency. We find an empirical model able to represent coherently all the non-harmonic lines we have found in the power spectrum, in terms of an assumed reference signal of the primary supply input signal. If this signal is not available then it can be reconstructed from the same data by making use of the coherent line removal algorithm that we have described elsewhere. All these lines are broadened by frequency changes of the supply signal, and they corrupt significant frequency ranges of the power spectrum. The physical process that generates this interference is so far unknown, but it is highly non-linear and non-stationary. Using our model, we cancel the interference in the time domain by an adaptive procedure that should work regardless of the source of the primary interference. We have applied the method to laser interferometer data from the Glasgow prototype detector, where all the features we describe in this paper were observed. The algorithm has been tuned in such a way that the entire series of wide lines corresponding to the electrical interference are removed, leaving the spectrum clean enough to detect signals previously masked by them. Single-line signals buried in the interference can be recovered with at least 75 % of their original signal amplitude. |
gr-qc/0108045 | S. Antoci | S. Antoci | A Rule for the Equilibrium of Forces in the Hermitian Theory of
Relativity | 7 pages; for the method of solution see e.g. gr-qc/0108042 | Annalen Phys. 44 (1987) 127 | null | null | gr-qc | null | When the behaviour of the singularities, which are used to represent masses,
charges or currents in exact solutions to the field equations of the Hermitian
theory of relativity, is restricted by a no-jump rule, conditions are obtained,
which determine the relative positions of masses, charges and currents. Due to
these conditions the Hermitian theory of relativity appears to provide a
unified description of gravitational, colour and electromagnetic forces.
| [
{
"created": "Fri, 17 Aug 2001 17:25:19 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Antoci",
"S.",
""
]
] | When the behaviour of the singularities, which are used to represent masses, charges or currents in exact solutions to the field equations of the Hermitian theory of relativity, is restricted by a no-jump rule, conditions are obtained, which determine the relative positions of masses, charges and currents. Due to these conditions the Hermitian theory of relativity appears to provide a unified description of gravitational, colour and electromagnetic forces. |
gr-qc/0511059 | Laszlo B. Szabados | Laszlo B Szabados | On a class of 2-surface observables in general relativity | 11 pages, a discussion of the observables in stationary spacetimes is
included, new references are added, typos corrected | Class.Quant.Grav. 23 (2006) 2291-2302 | 10.1088/0264-9381/23/7/006 | NI06005-GMR | gr-qc | null | The boundary conditions for canonical vacuum general relativity is
investigated at the quasi-local level. It is shown that fixing the area element
on the 2- surface S (rather than the induced 2-metric) is enough to have a well
defined constraint algebra, and a well defined Poisson algebra of basic
Hamiltonians parameterized by shifts that are tangent to and divergence-free on
$. The evolution equations preserve these boundary conditions and the value of
the basic Hamiltonian gives 2+2 covariant, gauge-invariant 2-surface
observables. The meaning of these observables is also discussed.
| [
{
"created": "Fri, 11 Nov 2005 15:18:07 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Feb 2006 16:30:51 GMT",
"version": "v2"
}
] | 2015-06-25 | [
[
"Szabados",
"Laszlo B",
""
]
] | The boundary conditions for canonical vacuum general relativity is investigated at the quasi-local level. It is shown that fixing the area element on the 2- surface S (rather than the induced 2-metric) is enough to have a well defined constraint algebra, and a well defined Poisson algebra of basic Hamiltonians parameterized by shifts that are tangent to and divergence-free on $. The evolution equations preserve these boundary conditions and the value of the basic Hamiltonian gives 2+2 covariant, gauge-invariant 2-surface observables. The meaning of these observables is also discussed. |
2007.11009 | Wenzer Qin | Wenzer Qin, Kimberly K. Boddy, and Marc Kamionkowski | Subluminal stochastic gravitational waves in pulsar-timing arrays and
astrometry | 12 pages, 5 figures, 1 table; v2: matches published version | Phys. Rev. D 103, 024045 (2021) | 10.1103/PhysRevD.103.024045 | MIT-CTP/5222 | gr-qc astro-ph.GA hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The detection of a stochastic background of low-frequency gravitational waves
by pulsar-timing and astrometric surveys will enable tests of gravitational
theories beyond general relativity. These theories generally permit
gravitational waves with non-Einsteinian polarization modes, which may
propagate slower than the speed of light. We use the total-angular-momentum
wave formalism to derive the angular correlation patterns of observables
relevant for pulsar timing arrays and astrometry that arise from a background
of subluminal gravitational waves with scalar, vector, or tensor polarizations.
We find that the pulsar timing observables for the scalar longitudinal mode,
which diverge with source distance in the luminal limit, are finite in the
subluminal case. Furthermore, we apply our results to $f(R)$ gravity, which
contains a massive scalar degree of freedom in addition to the standard
transverse-traceless modes. The scalar mode in this $f(R)$ theory is a linear
combination of the scalar-longitudinal and scalar-transverse modes, exciting
only the monopole and dipole for pulsar timing arrays and only the dipole for
astrometric surveys.
| [
{
"created": "Tue, 21 Jul 2020 18:00:05 GMT",
"version": "v1"
},
{
"created": "Mon, 25 Jan 2021 18:48:16 GMT",
"version": "v2"
}
] | 2021-01-26 | [
[
"Qin",
"Wenzer",
""
],
[
"Boddy",
"Kimberly K.",
""
],
[
"Kamionkowski",
"Marc",
""
]
] | The detection of a stochastic background of low-frequency gravitational waves by pulsar-timing and astrometric surveys will enable tests of gravitational theories beyond general relativity. These theories generally permit gravitational waves with non-Einsteinian polarization modes, which may propagate slower than the speed of light. We use the total-angular-momentum wave formalism to derive the angular correlation patterns of observables relevant for pulsar timing arrays and astrometry that arise from a background of subluminal gravitational waves with scalar, vector, or tensor polarizations. We find that the pulsar timing observables for the scalar longitudinal mode, which diverge with source distance in the luminal limit, are finite in the subluminal case. Furthermore, we apply our results to $f(R)$ gravity, which contains a massive scalar degree of freedom in addition to the standard transverse-traceless modes. The scalar mode in this $f(R)$ theory is a linear combination of the scalar-longitudinal and scalar-transverse modes, exciting only the monopole and dipole for pulsar timing arrays and only the dipole for astrometric surveys. |
1309.5596 | Victor Shchigolev Konstantinovich | V.K. Shchigolev | Homotopy Perturbation Method for Solving a Spatially Flat FRW
Cosmological Model | 5 pages, 3 figures | Universal Journal of Applied Mathematics 2(2): 99-103, 2014 | 10.13189/ujam.2014.020204 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the present paper, we study a homogeneous cosmological model in
Friedmann-Robertson-Walker (FRW) space-time by means of the so-called Homotopy
Perturbation Method (HPM). First, we briefly recall the main equations of the
cosmological model and the basic idea of HPM. Next we consider the test example
when the exact solution of the model is known, in order to approbate the HPM in
cosmology and present the main steps in solving by this method. Finally, we
obtain a solution for the spatially flat FRW model of the universe filled with
the dust and quintessence when the exact solution cannot be found. A comparison
of our solution with the corresponding numerical solution shows that it is of a
high degree of accuracy.
| [
{
"created": "Sun, 22 Sep 2013 13:09:14 GMT",
"version": "v1"
}
] | 2014-01-03 | [
[
"Shchigolev",
"V. K.",
""
]
] | In the present paper, we study a homogeneous cosmological model in Friedmann-Robertson-Walker (FRW) space-time by means of the so-called Homotopy Perturbation Method (HPM). First, we briefly recall the main equations of the cosmological model and the basic idea of HPM. Next we consider the test example when the exact solution of the model is known, in order to approbate the HPM in cosmology and present the main steps in solving by this method. Finally, we obtain a solution for the spatially flat FRW model of the universe filled with the dust and quintessence when the exact solution cannot be found. A comparison of our solution with the corresponding numerical solution shows that it is of a high degree of accuracy. |
1504.01547 | Mariusz Dabrowski P. | Mariusz P. Dabrowski and H. Gohar | Abolishing the maximum tension principle | 5 pages, no figures, REVTEX4-1, a typo in abstract corrected | Physics Letters B 748, Volume 748, pp 428-431 (2015) | 10.1016/j.physletb.2015.07.047 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We find the series of example theories for which the relativistic limit of
maximum tension $F_{max} = c^4/4G$ represented by the entropic force can be
abolished. Among them the varying constants theories, some generalized entropy
models applied both for cosmological and black hole horizons as well as some
generalized uncertainty principle models.
| [
{
"created": "Tue, 7 Apr 2015 11:01:12 GMT",
"version": "v1"
},
{
"created": "Fri, 10 Apr 2015 21:30:29 GMT",
"version": "v2"
},
{
"created": "Thu, 23 Apr 2015 19:55:52 GMT",
"version": "v3"
}
] | 2015-09-15 | [
[
"Dabrowski",
"Mariusz P.",
""
],
[
"Gohar",
"H.",
""
]
] | We find the series of example theories for which the relativistic limit of maximum tension $F_{max} = c^4/4G$ represented by the entropic force can be abolished. Among them the varying constants theories, some generalized entropy models applied both for cosmological and black hole horizons as well as some generalized uncertainty principle models. |
2104.07336 | Jose M. Carmona | Jos\'e Manuel Carmona, Jos\'e Luis Cort\'es and Jos\'e Javier Relancio | Curved momentum space, locality, and generalized space-time | 18 pages | Universe 7, 4 (2021) | 10.3390/universe7040099 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We establish the correspondence between two apparently unrelated but in fact
complementary approaches of a relativistic deformed kinematics: the geometric
properties of momentum space and the loss of absolute locality in canonical
spacetime, which can be restored with the introduction of a generalized
spacetime. This correspondence is made explicit for the case of
$\kappa$-Poincar\'e kinematics and compared with its properties in the Hopf
algebra framework.
| [
{
"created": "Thu, 15 Apr 2021 09:50:34 GMT",
"version": "v1"
}
] | 2021-04-16 | [
[
"Carmona",
"José Manuel",
""
],
[
"Cortés",
"José Luis",
""
],
[
"Relancio",
"José Javier",
""
]
] | We establish the correspondence between two apparently unrelated but in fact complementary approaches of a relativistic deformed kinematics: the geometric properties of momentum space and the loss of absolute locality in canonical spacetime, which can be restored with the introduction of a generalized spacetime. This correspondence is made explicit for the case of $\kappa$-Poincar\'e kinematics and compared with its properties in the Hopf algebra framework. |
2309.03121 | Jahed Abedi | Jahed Abedi, Collin D. Capano, Shilpa Kastha, Alexander H. Nitz,
Yi-Fan Wang, Julian Westerweck, Alex B. Nielsen, Badri Krishnan | Spectroscopy for asymmetric binary black hole mergers | 11 pages, 6 figures, 2 tables, accepted for publication in Phys. Rev.
D | null | 10.1103/PhysRevD.108.104009 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study Bayesian inference of black hole ringdown modes for simulated binary
black hole signals. We consider to what extent different fundamental ringdown
modes can be identified in the context of black hole spectroscopy. Our
simulated signals are inspired by the high mass event GW190521. We find strong
correlation between mass ratio and Bayes factors of the subdominant ringdown
modes. The Bayes factor values and time dependency, and the peak time of the
(3,3,0) mode align with those found analyzing the real event GW190521,
particularly for high-mass ratio systems.
| [
{
"created": "Wed, 6 Sep 2023 15:56:47 GMT",
"version": "v1"
},
{
"created": "Mon, 30 Oct 2023 01:30:29 GMT",
"version": "v2"
}
] | 2023-11-10 | [
[
"Abedi",
"Jahed",
""
],
[
"Capano",
"Collin D.",
""
],
[
"Kastha",
"Shilpa",
""
],
[
"Nitz",
"Alexander H.",
""
],
[
"Wang",
"Yi-Fan",
""
],
[
"Westerweck",
"Julian",
""
],
[
"Nielsen",
"Alex B.",
""
],
[
"Krishnan",
"Badri",
""
]
] | We study Bayesian inference of black hole ringdown modes for simulated binary black hole signals. We consider to what extent different fundamental ringdown modes can be identified in the context of black hole spectroscopy. Our simulated signals are inspired by the high mass event GW190521. We find strong correlation between mass ratio and Bayes factors of the subdominant ringdown modes. The Bayes factor values and time dependency, and the peak time of the (3,3,0) mode align with those found analyzing the real event GW190521, particularly for high-mass ratio systems. |
1402.2077 | Jacek Tafel | Ji\v{r}\'i Bi\v{c}\'ak and Jacek Tafel | Exact solutions and their interpretation - session A1 | 15 pages | Gen. Rel. Grav. (2014) 46:1685 | 10.1007/s10714-014-1685-3 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We report on the oral contributions and give a list of posters presented in
the session A1 "Exact solutions and their interpretation" at the 20th
International Conference on General Relativity and Gravitation (GR 20) in
Warsaw, July 7-13, 2013.
| [
{
"created": "Mon, 10 Feb 2014 09:33:10 GMT",
"version": "v1"
}
] | 2015-07-31 | [
[
"Bičák",
"Jiří",
""
],
[
"Tafel",
"Jacek",
""
]
] | We report on the oral contributions and give a list of posters presented in the session A1 "Exact solutions and their interpretation" at the 20th International Conference on General Relativity and Gravitation (GR 20) in Warsaw, July 7-13, 2013. |
1006.2229 | Wen-Biao Han | Wen-Biao Han | Chaos and dynamics of spinning particles in Kerr spacetime | 17 pages, 12 figures | Gen.Rel.Grav.40:1831-1847,2008 | 10.1007/s10714-007-0598-9 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study chaos dynamics of spinning particles in Kerr spacetime of rotating
black holes use the Papapetrou equations by numerical integration. Because of
spin, this system exists many chaos solutions, and exhibits some exceptional
dynamic character. We investigate the relations between the orbits chaos and
the spin magnitude S, pericenter, polar angle and Kerr rotation parameter a by
means of a kind of brand new Fast Lyapulov Indicator (FLI) which is defined in
general relativity. The classical definition of Lyapulov exponent (LE) perhaps
fails in curve spacetime. And we emphasize that the Poincar\'e sections cannot
be used to detect chaos for this case. Via calculations, some new interesting
conclusions are found: though chaos is easier to emerge with bigger S, but not
always depends on S monotonically; the Kerr parameter a has a contrary action
on the chaos occurrence. Furthermore, the spin of particles can destroy the
symmetry of the orbits about the equatorial plane. And for some special initial
conditions, the orbits have equilibrium points.
| [
{
"created": "Fri, 11 Jun 2010 08:28:17 GMT",
"version": "v1"
}
] | 2014-11-21 | [
[
"Han",
"Wen-Biao",
""
]
] | We study chaos dynamics of spinning particles in Kerr spacetime of rotating black holes use the Papapetrou equations by numerical integration. Because of spin, this system exists many chaos solutions, and exhibits some exceptional dynamic character. We investigate the relations between the orbits chaos and the spin magnitude S, pericenter, polar angle and Kerr rotation parameter a by means of a kind of brand new Fast Lyapulov Indicator (FLI) which is defined in general relativity. The classical definition of Lyapulov exponent (LE) perhaps fails in curve spacetime. And we emphasize that the Poincar\'e sections cannot be used to detect chaos for this case. Via calculations, some new interesting conclusions are found: though chaos is easier to emerge with bigger S, but not always depends on S monotonically; the Kerr parameter a has a contrary action on the chaos occurrence. Furthermore, the spin of particles can destroy the symmetry of the orbits about the equatorial plane. And for some special initial conditions, the orbits have equilibrium points. |
1111.4046 | Alexander Zhuk | Maxim Eingorn, Alexandra Kudinova and Alexander Zhuk | Non-relativistic limit of Randall-Sundrum model: solutions, applications
and constraints | LaTex 11 pages, 3 figures | General Relativity and Gravitation, 44 (2012) 2257-2270 | 10.1007/s10714-012-1387-7 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the Randall-Sundrum model with one brane, we found the approximate and
exact solutions for gravitational potentials and accelerations of test bodies
in these potentials for different geometrical configurations. We applied these
formulas for calculation of the gravitational interaction between two spheres
and found the approximate and exact expressions for the relative force
corrections to the Newton's gravitational force. We demonstrated that the
difference between relative force corrections for the approximate and exact
cases increases with the parameter $l$ (for the fixed distance $r$ between
centers of the spheres). On the other hand, this difference increases with
decreasing of the distance between the centers of the spheres (for the fixed
curvature scale parameter $l$). We got the upper limit for the curvature scale
parameter $l\lesssim 10\, \mu$m. For these values of $l$, the difference
between the approximate and exact solutions is negligible.
| [
{
"created": "Thu, 17 Nov 2011 10:09:01 GMT",
"version": "v1"
}
] | 2012-08-08 | [
[
"Eingorn",
"Maxim",
""
],
[
"Kudinova",
"Alexandra",
""
],
[
"Zhuk",
"Alexander",
""
]
] | In the Randall-Sundrum model with one brane, we found the approximate and exact solutions for gravitational potentials and accelerations of test bodies in these potentials for different geometrical configurations. We applied these formulas for calculation of the gravitational interaction between two spheres and found the approximate and exact expressions for the relative force corrections to the Newton's gravitational force. We demonstrated that the difference between relative force corrections for the approximate and exact cases increases with the parameter $l$ (for the fixed distance $r$ between centers of the spheres). On the other hand, this difference increases with decreasing of the distance between the centers of the spheres (for the fixed curvature scale parameter $l$). We got the upper limit for the curvature scale parameter $l\lesssim 10\, \mu$m. For these values of $l$, the difference between the approximate and exact solutions is negligible. |
2112.11863 | Steffen Aksteiner | Steffen Aksteiner and Lars Andersson | Gravitational Instantons and special geometry | Revised version, corrected typos and added references | null | null | null | gr-qc math.DG | http://creativecommons.org/licenses/by/4.0/ | The Chen-Teo gravitational instanton is an asymptotically flat, toric, Ricci
flat family of metrics on $\mathbb{C}\mathbb{P}^2\setminus S^1$, that provides
a counterexample to the classical Euclidean Black Hole Uniqueness conjecture.
In this paper we show that the Chen-Teo instanton is Hermitian and
non-K\"ahler. It follows that all known examples of gravitational instantons
are Hermitian.
| [
{
"created": "Wed, 22 Dec 2021 13:18:52 GMT",
"version": "v1"
},
{
"created": "Wed, 19 Jan 2022 12:29:37 GMT",
"version": "v2"
}
] | 2022-01-20 | [
[
"Aksteiner",
"Steffen",
""
],
[
"Andersson",
"Lars",
""
]
] | The Chen-Teo gravitational instanton is an asymptotically flat, toric, Ricci flat family of metrics on $\mathbb{C}\mathbb{P}^2\setminus S^1$, that provides a counterexample to the classical Euclidean Black Hole Uniqueness conjecture. In this paper we show that the Chen-Teo instanton is Hermitian and non-K\"ahler. It follows that all known examples of gravitational instantons are Hermitian. |
1907.05714 | Muhammad Sharif | M. Sharif and Aisha Siddiqa | Propagation of Polar Gravitational Waves in f(R,T) Scenario | 18 pages, 1 figures | Gen. Relativ. Gravit. 51(2019)74 | 10.1007/s10714-019-2558-6 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper investigates the propagation of polar gravitational waves in the
spatially flat FRW universe consisting of a perfect fluid in the scenario of
$R+2\lambda T$ model of $f(R,T)$ gravity ($\lambda$ being the model parameter).
The spatially flat universe model is perturbed via Regge-Wheeler perturbations
inducing polar gravitational waves and the field equations are formulated for
both unperturbed as well as perturbed spacetimes. We solve these field
equations simultaneously for the perturbation parameters introduced in the
metric, matter, and velocity in the radiation, as well as dark energy,
dominated phases. It is found that the polar gravitational waves can produce
changes in the background matter distribution as well as velocity components in
the radiation era similar to general relativity case. Moreover, we have
discussed the impact of model parameter on the amplitude of gravitational
waves.
| [
{
"created": "Thu, 11 Jul 2019 11:42:51 GMT",
"version": "v1"
}
] | 2019-07-17 | [
[
"Sharif",
"M.",
""
],
[
"Siddiqa",
"Aisha",
""
]
] | This paper investigates the propagation of polar gravitational waves in the spatially flat FRW universe consisting of a perfect fluid in the scenario of $R+2\lambda T$ model of $f(R,T)$ gravity ($\lambda$ being the model parameter). The spatially flat universe model is perturbed via Regge-Wheeler perturbations inducing polar gravitational waves and the field equations are formulated for both unperturbed as well as perturbed spacetimes. We solve these field equations simultaneously for the perturbation parameters introduced in the metric, matter, and velocity in the radiation, as well as dark energy, dominated phases. It is found that the polar gravitational waves can produce changes in the background matter distribution as well as velocity components in the radiation era similar to general relativity case. Moreover, we have discussed the impact of model parameter on the amplitude of gravitational waves. |
gr-qc/0609025 | Jonn Miritzis | John Miritzis | The recollapse problem of closed isotropic models in second order
gravity theory | 9 pages, 1 figure. Talk given at the Eleventh Marcel Grossmann
Meeting on General Relativity, Berlin 2006 | null | null | null | gr-qc | null | We study the closed universe recollapse conjecture for positively curved
Friedmann-Robertson-Walker (FRW) models in the Jordan frame of the second order
gravity theory. We analyse the late time evolution of the model with the
methods of the dynamical systems. We find that an initially expanding closed
FRW universe, starting close to the Minkowski spacetime, may exhibit
oscillatory behaviour.
| [
{
"created": "Thu, 7 Sep 2006 15:25:51 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Miritzis",
"John",
""
]
] | We study the closed universe recollapse conjecture for positively curved Friedmann-Robertson-Walker (FRW) models in the Jordan frame of the second order gravity theory. We analyse the late time evolution of the model with the methods of the dynamical systems. We find that an initially expanding closed FRW universe, starting close to the Minkowski spacetime, may exhibit oscillatory behaviour. |
gr-qc/9801105 | Alessandra Buonanno | Alessandra Buonanno, Thibault Damour | On the gravitational, dilatonic and axionic radiative damping of cosmic
strings | 48 pages, RevTex, epsfig, 1 figure; clarification of the domain of
validity of the perturbative derivation of the string equations of motion,
and of their renormalizability | Phys.Rev. D60 (1999) 023517 | 10.1103/PhysRevD.60.023517 | IHES/P/98/6 | gr-qc astro-ph hep-th | null | We study the radiation reaction on cosmic strings due to the emission of
dilatonic, gravitational and axionic waves. After verifying the (on average)
conservative nature of the time-symmetric self-interactions, we concentrate on
the finite radiation damping force associated with the half-retarded minus
half-advanced ``reactive'' fields. We revisit a recent proposal of using a
``local back reaction approximation'' for the reactive fields. Using
dimensional continuation as convenient technical tool, we find, contrary to
previous claims, that this proposal leads to antidamping in the case of the
axionic field, and to zero (integrated) damping in the case of the
gravitational field. One gets normal positive damping only in the case of the
dilatonic field. We propose to use a suitably modified version of the local
dilatonic radiation reaction as a substitute for the exact (non-local)
gravitational radiation reaction. The incorporation of such a local
approximation to gravitational radiation reaction should allow one to complete,
in a computationally non-intensive way, string network simulations and to give
better estimates of the amount and spectrum of gravitational radiation emitted
by a cosmologically evolving network of massive strings.
| [
{
"created": "Thu, 29 Jan 1998 18:29:15 GMT",
"version": "v1"
},
{
"created": "Wed, 4 Mar 1998 18:06:18 GMT",
"version": "v2"
},
{
"created": "Thu, 17 Jun 1999 19:11:43 GMT",
"version": "v3"
}
] | 2009-10-31 | [
[
"Buonanno",
"Alessandra",
""
],
[
"Damour",
"Thibault",
""
]
] | We study the radiation reaction on cosmic strings due to the emission of dilatonic, gravitational and axionic waves. After verifying the (on average) conservative nature of the time-symmetric self-interactions, we concentrate on the finite radiation damping force associated with the half-retarded minus half-advanced ``reactive'' fields. We revisit a recent proposal of using a ``local back reaction approximation'' for the reactive fields. Using dimensional continuation as convenient technical tool, we find, contrary to previous claims, that this proposal leads to antidamping in the case of the axionic field, and to zero (integrated) damping in the case of the gravitational field. One gets normal positive damping only in the case of the dilatonic field. We propose to use a suitably modified version of the local dilatonic radiation reaction as a substitute for the exact (non-local) gravitational radiation reaction. The incorporation of such a local approximation to gravitational radiation reaction should allow one to complete, in a computationally non-intensive way, string network simulations and to give better estimates of the amount and spectrum of gravitational radiation emitted by a cosmologically evolving network of massive strings. |
1712.01159 | Pedro Bargueno | A. F. Vargas, E. Contreras and P. Bargue\~no | SAdS black holes and spacetime atoms: a heuristic approach | Accepted for publication in Gen. Rel. Grav | General Relativity and Gravitation (2018) 50:117 | 10.1007/s10714-018-2442-9 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, both extended phase space and holographic equipartition
approaches are employed to develop an exact Van der Waals description of
non--rotating $D=4$ SAdS black holes as an ensemble of spacetime atoms. After a
possible microscopical interaction model is introduced, statistical mechanics
techniques, with certain heuristic gravitational constraints, are used to
derive the equation of state and the Bekenstein--Hawking entropy. The procedure
is generalized to the charged $D=4$ SAdS black hole and to arbitrary $D\ge 3$
dimensions for the uncharged cases.
| [
{
"created": "Mon, 4 Dec 2017 15:51:57 GMT",
"version": "v1"
},
{
"created": "Fri, 17 Aug 2018 18:11:29 GMT",
"version": "v2"
},
{
"created": "Fri, 24 Aug 2018 16:41:06 GMT",
"version": "v3"
}
] | 2018-08-27 | [
[
"Vargas",
"A. F.",
""
],
[
"Contreras",
"E.",
""
],
[
"Bargueño",
"P.",
""
]
] | In this work, both extended phase space and holographic equipartition approaches are employed to develop an exact Van der Waals description of non--rotating $D=4$ SAdS black holes as an ensemble of spacetime atoms. After a possible microscopical interaction model is introduced, statistical mechanics techniques, with certain heuristic gravitational constraints, are used to derive the equation of state and the Bekenstein--Hawking entropy. The procedure is generalized to the charged $D=4$ SAdS black hole and to arbitrary $D\ge 3$ dimensions for the uncharged cases. |
gr-qc/0611119 | Narit Pidokrajt | Jan E Aman, James Bedford, Daniel Grumiller, Narit Pidokrajt and John
Ward | Ruppeiner theory of black hole thermodynamics | 10 pages, 1 figure. Talk given by N Pidokrajt at ERE2006 in Palma de
Mallorca, Spain | J.Phys.Conf.Ser.66:012007,2007 | 10.1088/1742-6596/66/1/012007 | MIT-CTP 3787, QMUL-PH-06-09, USITP 06-04 | gr-qc hep-th | null | The Ruppeiner metric as determined by the Hessian of the Gibbs surface
provides a geometric description of thermodynamic systems in equilibrium. An
interesting example is a black hole in equilibrium with its own Hawking
radiation. In this article, we present results from the Ruppeiner study of
various black hole families from different gravity theories e.g. 2D dilaton
gravity, BTZ, general relativity and higher-dimensional Einstein-Maxwell
gravity.
| [
{
"created": "Wed, 22 Nov 2006 21:53:51 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Aman",
"Jan E",
""
],
[
"Bedford",
"James",
""
],
[
"Grumiller",
"Daniel",
""
],
[
"Pidokrajt",
"Narit",
""
],
[
"Ward",
"John",
""
]
] | The Ruppeiner metric as determined by the Hessian of the Gibbs surface provides a geometric description of thermodynamic systems in equilibrium. An interesting example is a black hole in equilibrium with its own Hawking radiation. In this article, we present results from the Ruppeiner study of various black hole families from different gravity theories e.g. 2D dilaton gravity, BTZ, general relativity and higher-dimensional Einstein-Maxwell gravity. |
gr-qc/0502011 | Jiliang Jing | Jiliang Jing and Qiyuan Pan | Dirac quasinormal frequencies of Reissner-Nordstr\"om black hole in
Anti-de Sitter spacetime | 16 pages, 4 figures | Phys.Rev. D71 (2005) 124011 | 10.1103/PhysRevD.71.124011 | null | gr-qc astro-ph hep-th | null | The quasinormal modes (QNMs) of Dirac field perturbations of a
Reissner-Nordstr\"om black hole in an asymptotically Anti-de Sitter spacetime
are investigated. We find that both the real and imaginary parts of the
fundamental quasinormal frequencies for large black holes are the linear
functions of the Hawking temperature, and the slope of the lines for the real
parts decreases while that for the magnitude of the imaginary parts increases
as the black hole charge increases. According to the Anti-de Sitter/Conformal
Field Theory (AdS/CFT) correspondence, the fact shows that different charge
presents different time scale in three-dimensional CFT. Another interesting
result is that the quasinormal frequencies become evenly spaced for high
overtone number, and in the spacing expressions the real part decreases while
the magnitude of the imaginary part increases as the charge increases. We also
study the relation between quasinormal frequencies and angular quantum number
and find that the real part increases while the magnitude of the imaginary part
decreases as the angular quantum number increases.
| [
{
"created": "Thu, 3 Feb 2005 03:32:50 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Jing",
"Jiliang",
""
],
[
"Pan",
"Qiyuan",
""
]
] | The quasinormal modes (QNMs) of Dirac field perturbations of a Reissner-Nordstr\"om black hole in an asymptotically Anti-de Sitter spacetime are investigated. We find that both the real and imaginary parts of the fundamental quasinormal frequencies for large black holes are the linear functions of the Hawking temperature, and the slope of the lines for the real parts decreases while that for the magnitude of the imaginary parts increases as the black hole charge increases. According to the Anti-de Sitter/Conformal Field Theory (AdS/CFT) correspondence, the fact shows that different charge presents different time scale in three-dimensional CFT. Another interesting result is that the quasinormal frequencies become evenly spaced for high overtone number, and in the spacing expressions the real part decreases while the magnitude of the imaginary part increases as the charge increases. We also study the relation between quasinormal frequencies and angular quantum number and find that the real part increases while the magnitude of the imaginary part decreases as the angular quantum number increases. |
1407.2604 | Mohammad Reza Setare | M. R. Setare and V. Kamali | Cosmological perturbations in warm-tachyon inflationary universe model
with viscous pressure | 19 pages, 3 figures, accepted for publication in PLB (2014). arXiv
admin note: substantial text overlap with arXiv:1302.0493, arXiv:1312.2832 | null | 10.1016/j.physletb.2014.07.008 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the warm-tachyon inflationary universe model with viscous pressure
in high-dissipation regime. General conditions which are required for this
model to be realizable are derived in the slow-roll approximation. We present
analytic expressions for density perturbation and amplitude of tensor
perturbation in longitudinal gauge. Expressions of tensor-to-scalar ratio,
scalar spectral index and its running are obtained. We develop our model by
using exponential potential, the characteristics of this model are calculated
for two specific cases in great details: 1- Dissipative parameter $\Gamma$ and
bulk viscous parameter $\zeta$ are constant parameters. 2- Dissipative
parameter is a function of tachyon field $\phi$ and bulk viscous parameter is a
function of matter-radiation mixture energy density $\rho$. The parameters of
the model are restricted by recent observational data from the nine-year
Wilkinson microwave anisotropy probe (WMAP9), Planck and BICEP2 data.
| [
{
"created": "Wed, 9 Jul 2014 10:58:15 GMT",
"version": "v1"
}
] | 2015-06-22 | [
[
"Setare",
"M. R.",
""
],
[
"Kamali",
"V.",
""
]
] | We study the warm-tachyon inflationary universe model with viscous pressure in high-dissipation regime. General conditions which are required for this model to be realizable are derived in the slow-roll approximation. We present analytic expressions for density perturbation and amplitude of tensor perturbation in longitudinal gauge. Expressions of tensor-to-scalar ratio, scalar spectral index and its running are obtained. We develop our model by using exponential potential, the characteristics of this model are calculated for two specific cases in great details: 1- Dissipative parameter $\Gamma$ and bulk viscous parameter $\zeta$ are constant parameters. 2- Dissipative parameter is a function of tachyon field $\phi$ and bulk viscous parameter is a function of matter-radiation mixture energy density $\rho$. The parameters of the model are restricted by recent observational data from the nine-year Wilkinson microwave anisotropy probe (WMAP9), Planck and BICEP2 data. |
2203.00661 | Ernesto Contreras | Pio J. Arias, Pedro Bargue\~no, Ernesto Contreras, Ernesto Fuenmayor | $2+1$ Einstein-Klein-Gordon black holes by gravitational decoupling | null | Astronomy 1, 2 (2022) | 10.3390/astronomy1010002 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we study the 2+1 Einstein-Klein-Gordon system in the framework
of Gravitational Decoupling. We associate the generic matter decoupling sector
with a real scalar field so we can obtain a constraint which allows to close
the system of differential equations. The constraint corresponds to a
differential equation involving the decoupling functions and the metric of the
seed sector and will be independent of the scalar field itself. We show that
when the equation admits analytical solutions, the scalar field and the
self-interacting potential can be obtained straightforwardly. We found that, in
the cases under consideration, it is possible to express the potential as an
explicit function of the scalar field only for certain particular cases
corresponding to limiting values of the parameters involved.
| [
{
"created": "Tue, 1 Mar 2022 18:14:29 GMT",
"version": "v1"
},
{
"created": "Fri, 4 Mar 2022 00:09:44 GMT",
"version": "v2"
}
] | 2022-03-07 | [
[
"Arias",
"Pio J.",
""
],
[
"Bargueño",
"Pedro",
""
],
[
"Contreras",
"Ernesto",
""
],
[
"Fuenmayor",
"Ernesto",
""
]
] | In this work we study the 2+1 Einstein-Klein-Gordon system in the framework of Gravitational Decoupling. We associate the generic matter decoupling sector with a real scalar field so we can obtain a constraint which allows to close the system of differential equations. The constraint corresponds to a differential equation involving the decoupling functions and the metric of the seed sector and will be independent of the scalar field itself. We show that when the equation admits analytical solutions, the scalar field and the self-interacting potential can be obtained straightforwardly. We found that, in the cases under consideration, it is possible to express the potential as an explicit function of the scalar field only for certain particular cases corresponding to limiting values of the parameters involved. |
1905.00010 | Nils Andersson | N. Andersson and P. Pnigouras | The g-mode spectrum of reactive neutron star cores | 7 pages, 2 figures | null | 10.1093/mnras/stz2449 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss the impact of nuclear reactions on the spectrum of gravity g-modes
of a mature neutron star, demonstrating the anticipated disappearance of these
modes when the timescale associated with the oscillations is longer than that
of nuclear reactions. This is the expected result, but different aspects of the
demonstration may be relevant for related problems in neutron star
astrophysics. In particular, we develop the framework required for an explicit
implementation of finite-time nuclear reactions in neutron star oscillation
problems and demonstrate how this formulation connects with the usual bulk
viscosity prescription. We also discuss implications of the absence of very
high order g-modes for problems of astrophysical relevance.
| [
{
"created": "Tue, 30 Apr 2019 16:57:25 GMT",
"version": "v1"
}
] | 2019-09-25 | [
[
"Andersson",
"N.",
""
],
[
"Pnigouras",
"P.",
""
]
] | We discuss the impact of nuclear reactions on the spectrum of gravity g-modes of a mature neutron star, demonstrating the anticipated disappearance of these modes when the timescale associated with the oscillations is longer than that of nuclear reactions. This is the expected result, but different aspects of the demonstration may be relevant for related problems in neutron star astrophysics. In particular, we develop the framework required for an explicit implementation of finite-time nuclear reactions in neutron star oscillation problems and demonstrate how this formulation connects with the usual bulk viscosity prescription. We also discuss implications of the absence of very high order g-modes for problems of astrophysical relevance. |
gr-qc/0402062 | Jorge Pullin | Rodolfo Gambini and Jorge Pullin | Canonical quantum gravity and consistent discretizations | 8 pages, to appear in Pramana | Pramana63:755-764,2004 | 10.1007/BF02705197 | LSU-REL-021304 | gr-qc | null | This is a summary of the talk presented by JP at ICGC2004. It covered some
developments in canonical quantum gravity occurred since ICGC2000, emphasizing
the recently introduced consistent discretizations of general relativity.
| [
{
"created": "Fri, 13 Feb 2004 16:49:30 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Gambini",
"Rodolfo",
""
],
[
"Pullin",
"Jorge",
""
]
] | This is a summary of the talk presented by JP at ICGC2004. It covered some developments in canonical quantum gravity occurred since ICGC2000, emphasizing the recently introduced consistent discretizations of general relativity. |
2112.01706 | Shao-Wen Wei | Shao-Wen Wei, Yu-Xiao Liu | Topology of black hole thermodynamics | 6 pages and 6 figures | Phys.Rev.D 105, 104003 (2022) | 10.1103/PhysRevD.105.104003 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | A critical point is an important structure in the phase diagram of a
thermodynamic system. In this work, we introduce topology to the study of the
black hole thermodynamics for the first time by following Duan's topological
current $\phi$-mapping theory. Each critical point is endowed with a
topological charge. We find that critical points can be divided into two
classes, the conventional and the novel. Further study shows that the
first-order phase transition can extend from the conventional critical point,
while the presence of the novel critical point cannot serve as an indicator of
the presence of the first-order phase transition near it. Moreover, the charged
anti-de Sitter black hole and the Born-Infeld anti-de Sitter black hole have
different topological charges, which indicates they are in different
topological classes from the viewpoint of thermodynamics. These give the first
promising study on the topology of the black hole thermodynamics. Such approach
is also expected to be extended to other black holes, and much more topological
information remains to be disclosed.
| [
{
"created": "Fri, 3 Dec 2021 04:30:42 GMT",
"version": "v1"
},
{
"created": "Wed, 19 Jan 2022 03:04:29 GMT",
"version": "v2"
},
{
"created": "Tue, 10 May 2022 08:27:12 GMT",
"version": "v3"
}
] | 2022-05-11 | [
[
"Wei",
"Shao-Wen",
""
],
[
"Liu",
"Yu-Xiao",
""
]
] | A critical point is an important structure in the phase diagram of a thermodynamic system. In this work, we introduce topology to the study of the black hole thermodynamics for the first time by following Duan's topological current $\phi$-mapping theory. Each critical point is endowed with a topological charge. We find that critical points can be divided into two classes, the conventional and the novel. Further study shows that the first-order phase transition can extend from the conventional critical point, while the presence of the novel critical point cannot serve as an indicator of the presence of the first-order phase transition near it. Moreover, the charged anti-de Sitter black hole and the Born-Infeld anti-de Sitter black hole have different topological charges, which indicates they are in different topological classes from the viewpoint of thermodynamics. These give the first promising study on the topology of the black hole thermodynamics. Such approach is also expected to be extended to other black holes, and much more topological information remains to be disclosed. |
2206.08179 | Leanne Durkan | Leanne Durkan and Niels Warburton | Slow evolution of the metric perturbation due to a quasicircular
inspiral into a Schwarzschild black hole | 23 pages, (15 pages with appendices and references), 7 figures, 1
table | null | 10.1103/PhysRevD.106.084023 | null | gr-qc | http://creativecommons.org/licenses/by-nc-sa/4.0/ | Extreme mass-ratio inspirals (EMRIs) are one of the most highly anticipated
sources of gravitational radiation novel to detection by millihertz space-based
detectors. To accurately estimate the parameters of EMRIs and perform precision
tests of general relativity, their models should incorporate self-force theory
through second-order in the small mass ratio. Due to their extreme mass ratio,
EMRIs inspiral slowly when sufficiently far from merger. As such, the slow
evolution of the first-order metric perturbation contributes to the source for
the second-order metric perturbation, and must be accounted for in EMRI
waveform models. In this paper we calculate the slow evolution of the
first-order metric perturbation in the Lorenz gauge for quasicircular orbits on
a Schwarzschild background in the frequency domain. Lorenz gauge solutions to
the first-order metric perturbation and its slow evolution are obtained via a
gauge transformation from Regge-Wheeler gauge solutions. The slow evolution of
Regge-Wheeler and Zerilli master functions, in addition to a gauge field are
determined using the method of partial annihilators.
| [
{
"created": "Thu, 16 Jun 2022 13:45:39 GMT",
"version": "v1"
},
{
"created": "Thu, 18 May 2023 21:22:45 GMT",
"version": "v2"
}
] | 2023-05-22 | [
[
"Durkan",
"Leanne",
""
],
[
"Warburton",
"Niels",
""
]
] | Extreme mass-ratio inspirals (EMRIs) are one of the most highly anticipated sources of gravitational radiation novel to detection by millihertz space-based detectors. To accurately estimate the parameters of EMRIs and perform precision tests of general relativity, their models should incorporate self-force theory through second-order in the small mass ratio. Due to their extreme mass ratio, EMRIs inspiral slowly when sufficiently far from merger. As such, the slow evolution of the first-order metric perturbation contributes to the source for the second-order metric perturbation, and must be accounted for in EMRI waveform models. In this paper we calculate the slow evolution of the first-order metric perturbation in the Lorenz gauge for quasicircular orbits on a Schwarzschild background in the frequency domain. Lorenz gauge solutions to the first-order metric perturbation and its slow evolution are obtained via a gauge transformation from Regge-Wheeler gauge solutions. The slow evolution of Regge-Wheeler and Zerilli master functions, in addition to a gauge field are determined using the method of partial annihilators. |
2101.04060 | Souvik Ghose | Arindam Saha, Souvik Ghose, Anirban Chanda, Bikash Chandra Paul | R\' enyi Holographic Dark Energy in Higher Dimension Cosmology | 17 pages, 11 figures, Accepted for publication in Annals of Physics | null | 10.1016/j.aop.2021.168403 | null | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | R\'enyi holographic dark energy (RHDE) correspondence is discussed in higher
dimensional cosmology, namely Kaluza-Klein (KK) cosmology. Both interacting and
non-interacting cosmological scenario are considered here. It is found that the
non-interacting model naturally leads to the late accelerated universe, unlike
the standard Holographic Dark Energy models in 4$D$, which requires interaction
to accommodate the late-time acceleration of the universe. The interacting
model produces an accelerating universe at late time albeit failing to attain
the estimated present value of the deceleration parameter. The evolution of
different cosmologically relevant parameters have been estimated. We consider
here two diagnostic tests namely, state-finder and $Om$ diagnostics to study
the non-interacting model which is more favoured in the light of recent
cosmological observations. Classical stability of the cosmological models are
also discussed
| [
{
"created": "Mon, 11 Jan 2021 17:52:23 GMT",
"version": "v1"
}
] | 2021-01-22 | [
[
"Saha",
"Arindam",
""
],
[
"Ghose",
"Souvik",
""
],
[
"Chanda",
"Anirban",
""
],
[
"Paul",
"Bikash Chandra",
""
]
] | R\'enyi holographic dark energy (RHDE) correspondence is discussed in higher dimensional cosmology, namely Kaluza-Klein (KK) cosmology. Both interacting and non-interacting cosmological scenario are considered here. It is found that the non-interacting model naturally leads to the late accelerated universe, unlike the standard Holographic Dark Energy models in 4$D$, which requires interaction to accommodate the late-time acceleration of the universe. The interacting model produces an accelerating universe at late time albeit failing to attain the estimated present value of the deceleration parameter. The evolution of different cosmologically relevant parameters have been estimated. We consider here two diagnostic tests namely, state-finder and $Om$ diagnostics to study the non-interacting model which is more favoured in the light of recent cosmological observations. Classical stability of the cosmological models are also discussed |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.