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
|
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1008.0796
|
Bijunath Patla
|
James D. Phillips, Bijunath R. Patla, Eugeniu M. Popescu, Emanuele
Rocco, Rajesh Thapa, Robert D. Reasenberg and Enrico C. Lorenzini
|
Weak Equivalence Principle Test on a Sounding Rocket
|
Presented at the Fifth Meeting on CPT and Lorentz Symmetry,
Bloomington, Indiana, June 28-July 2, 2010
| null |
10.1142/9789814327688_0040
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
SR-POEM, our principle of equivalence measurement on a sounding rocket, will
compare the free fall rate of two substances yielding an uncertainty of E-16 in
the estimate of \eta. During the past two years, the design concept has matured
and we have been working on the required technology, including a laser gauge
that is self aligning and able to reach 0.1 pm per root hertz for periods up to
40 s. We describe the status and plans for this project.
|
[
{
"created": "Wed, 4 Aug 2010 14:54:26 GMT",
"version": "v1"
}
] |
2017-08-23
|
[
[
"Phillips",
"James D.",
""
],
[
"Patla",
"Bijunath R.",
""
],
[
"Popescu",
"Eugeniu M.",
""
],
[
"Rocco",
"Emanuele",
""
],
[
"Thapa",
"Rajesh",
""
],
[
"Reasenberg",
"Robert D.",
""
],
[
"Lorenzini",
"Enrico C.",
""
]
] |
SR-POEM, our principle of equivalence measurement on a sounding rocket, will compare the free fall rate of two substances yielding an uncertainty of E-16 in the estimate of \eta. During the past two years, the design concept has matured and we have been working on the required technology, including a laser gauge that is self aligning and able to reach 0.1 pm per root hertz for periods up to 40 s. We describe the status and plans for this project.
|
gr-qc/0703073
|
Ingemar Eriksson
|
G. Bergqvist and I. Eriksson
|
The Chevreton Tensor and Einstein-Maxwell Spacetimes Conformal to
Einstein Spaces
|
22 pages. Corrected equation (12)
|
Class.Quant.Grav.24:3437-3456,2007
|
10.1088/0264-9381/24/13/018
| null |
gr-qc
| null |
In this paper we characterize the source-free Einstein-Maxwell spacetimes
which have a trace-free Chevreton tensor. We show that this is equivalent to
the Chevreton tensor being of pure-radiation type and that it restricts the
spacetimes to Petrov types \textbf{N} or \textbf{O}. We prove that the trace of
the Chevreton tensor is related to the Bach tensor and use this to find all
Einstein-Maxwell spacetimes with a zero cosmological constant that have a
vanishing Bach tensor. Among these spacetimes we then look for those which are
conformal to Einstein spaces. We find that the electromagnetic field and the
Weyl tensor must be aligned, and in the case that the electromagnetic field is
null, the spacetime must be conformally Ricci-flat and all such solutions are
known. In the non-null case, since the general solution is not known on closed
form, we settle with giving the integrability conditions in the general case,
but we do give new explicit examples of Einstein-Maxwell spacetimes that are
conformal to Einstein spaces, and we also find examples where the vanishing of
the Bach tensor does not imply that the spacetime is conformal to a $C$-space.
The non-aligned Einstein-Maxwell spacetimes with vanishing Bach tensor are
conformally $C$-spaces, but none of them are conformal to Einstein spaces.
|
[
{
"created": "Tue, 13 Mar 2007 17:48:39 GMT",
"version": "v1"
},
{
"created": "Fri, 16 Mar 2007 12:47:08 GMT",
"version": "v2"
}
] |
2008-11-26
|
[
[
"Bergqvist",
"G.",
""
],
[
"Eriksson",
"I.",
""
]
] |
In this paper we characterize the source-free Einstein-Maxwell spacetimes which have a trace-free Chevreton tensor. We show that this is equivalent to the Chevreton tensor being of pure-radiation type and that it restricts the spacetimes to Petrov types \textbf{N} or \textbf{O}. We prove that the trace of the Chevreton tensor is related to the Bach tensor and use this to find all Einstein-Maxwell spacetimes with a zero cosmological constant that have a vanishing Bach tensor. Among these spacetimes we then look for those which are conformal to Einstein spaces. We find that the electromagnetic field and the Weyl tensor must be aligned, and in the case that the electromagnetic field is null, the spacetime must be conformally Ricci-flat and all such solutions are known. In the non-null case, since the general solution is not known on closed form, we settle with giving the integrability conditions in the general case, but we do give new explicit examples of Einstein-Maxwell spacetimes that are conformal to Einstein spaces, and we also find examples where the vanishing of the Bach tensor does not imply that the spacetime is conformal to a $C$-space. The non-aligned Einstein-Maxwell spacetimes with vanishing Bach tensor are conformally $C$-spaces, but none of them are conformal to Einstein spaces.
|
2107.01455
|
Hideki Maeda
|
Hideki Maeda
|
Hawking-Ellis type of matter on Killing horizons in symmetric spacetimes
|
7 pages, 1 table, no figure; v3, final version published in Physical
Review D
|
Phys.Rev.D 104 (2021) 8, 084088
|
10.1103/PhysRevD.104.084088
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Spherically, plane, or hyperbolically symmetric spacetimes with an additional
hypersurface orthogonal Killing vector are often called ``static'' spacetimes
even if they contain regions where the Killing vector is non-timelike. It seems
to be widely believed that an energy-momentum tenor for a matter field
compatible with these spacetimes in general relativity is of the Hawking-Ellis
type I everywhere. We show in arbitrary $n(\ge 3)$ dimensions that, contrary to
popular belief, a matter field on a Killing horizon is not necessarily of type
I but can be of type II. Such a type-II matter field on a Killing horizon is
realized in the Gibbons-Maeda-Garfinkle-Horowitz-Strominger black hole in the
Einstein-Maxwell-dilaton system and may be interpreted as a mixture of a
particular anisotropic fluid and a null dust fluid.
|
[
{
"created": "Sat, 3 Jul 2021 15:52:20 GMT",
"version": "v1"
},
{
"created": "Sat, 7 Aug 2021 12:49:53 GMT",
"version": "v2"
},
{
"created": "Mon, 1 Nov 2021 09:41:12 GMT",
"version": "v3"
}
] |
2021-11-02
|
[
[
"Maeda",
"Hideki",
""
]
] |
Spherically, plane, or hyperbolically symmetric spacetimes with an additional hypersurface orthogonal Killing vector are often called ``static'' spacetimes even if they contain regions where the Killing vector is non-timelike. It seems to be widely believed that an energy-momentum tenor for a matter field compatible with these spacetimes in general relativity is of the Hawking-Ellis type I everywhere. We show in arbitrary $n(\ge 3)$ dimensions that, contrary to popular belief, a matter field on a Killing horizon is not necessarily of type I but can be of type II. Such a type-II matter field on a Killing horizon is realized in the Gibbons-Maeda-Garfinkle-Horowitz-Strominger black hole in the Einstein-Maxwell-dilaton system and may be interpreted as a mixture of a particular anisotropic fluid and a null dust fluid.
|
gr-qc/0509042
|
Pavel Nakaznoy A
|
P.I.Fomin, P.A.Nakaznoy, S.I.Vilchinskyi
|
The Closed Cosmological Model with Variable Lambda-term
|
The 13-th general Conference of the European Physical Society "Beyond
Einstein - Physics for the 21-st Century", Bern 2005
| null | null | null |
gr-qc
| null |
We have studied the closed universe model with the variable cosmological
term, which is presented as a sum of two terms: Lambda=Lambda_0 -k R. First
term Lambda_0 is a constant and it is describing a sum of quantum field's zero
oscillations. In the geometrical sense it determines an own constant curvature
of the space-time. The second term is variable, it is proportional to curvature
of the space-time and can be interpretable as response of vacuum to curvature
of the space-time. In the framework of such model we have investigated the time
dynamic of Lambda-term and try to explain a mechanism which to give rise to a
large value of Lambda hence leading to the "cosmological constant problem". It
was studied models for different dark matter equation of state: p=0 and
p=varepsilon. It was shown that the presence of a variable Lambda-term alters
the evolution of the scale factor a in the very early epoch. In the context of
this model, a severe decrease of the module of vacuum energy density at the
primitive stage of Universe's development is explained. The numerical results
for the value of the Lambda-term agree with theoretical predictions for the
early epoch and with recent observation data.
|
[
{
"created": "Tue, 13 Sep 2005 18:41:11 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Fomin",
"P. I.",
""
],
[
"Nakaznoy",
"P. A.",
""
],
[
"Vilchinskyi",
"S. I.",
""
]
] |
We have studied the closed universe model with the variable cosmological term, which is presented as a sum of two terms: Lambda=Lambda_0 -k R. First term Lambda_0 is a constant and it is describing a sum of quantum field's zero oscillations. In the geometrical sense it determines an own constant curvature of the space-time. The second term is variable, it is proportional to curvature of the space-time and can be interpretable as response of vacuum to curvature of the space-time. In the framework of such model we have investigated the time dynamic of Lambda-term and try to explain a mechanism which to give rise to a large value of Lambda hence leading to the "cosmological constant problem". It was studied models for different dark matter equation of state: p=0 and p=varepsilon. It was shown that the presence of a variable Lambda-term alters the evolution of the scale factor a in the very early epoch. In the context of this model, a severe decrease of the module of vacuum energy density at the primitive stage of Universe's development is explained. The numerical results for the value of the Lambda-term agree with theoretical predictions for the early epoch and with recent observation data.
|
2308.01310
|
Gaurav Narain
|
Manishankar Ailiga, Shubhashis Mallik, Gaurav Narain
|
Lorentzian Robin Universe
|
v3: Accepted in JHEP. 1+38 pages, 5 figures. Text and references
added
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, we delve into the gravitational path integral of Gauss-Bonnet
gravity in four spacetime dimensions, in the mini-superspace approximation. Our
primary focus lies in investigating the transition amplitude between distinct
boundary configurations. Of particular interest is the case of Robin boundary
conditions, known to lead to a stable Universe in Einstein-Hilbert gravity,
alongside Neumann boundary conditions. To ensure a consistent variational
problem, we supplement the bulk action with suitable surface terms. This study
leads us to compute the necessary surface terms required for Gauss-Bonnet
gravity with the Robin boundary condition, which wasn't known earlier.
Thereafter, we perform an exact computation of the transition amplitude.
Through $\hbar\to0$ analysis, we discover that the Gauss-Bonnet gravity
inherently favors the initial configuration, aligning with the Hartle-Hawking
no-boundary proposal. Remarkably, as the Universe expands, it undergoes a
transition from the Euclidean (imaginary time) to the Lorentzian signature
(real time). To further reinforce our findings, we employ a saddle point
analysis utilizing the Picard-Lefschetz methods. The saddle point analysis
allows us to find the initial configurations which lead to Hartle-Hawking
no-boundary Universe that agrees with the exact computations. Our study
concludes that for positive Gauss-Bonnet coupling, initial configurations
corresponding to the Hartle-Hawking no-boundary Universe gives dominant
contribution in the gravitational path-integral.
|
[
{
"created": "Wed, 2 Aug 2023 17:55:49 GMT",
"version": "v1"
},
{
"created": "Fri, 4 Aug 2023 17:11:12 GMT",
"version": "v2"
},
{
"created": "Mon, 8 Jan 2024 18:09:57 GMT",
"version": "v3"
}
] |
2024-01-09
|
[
[
"Ailiga",
"Manishankar",
""
],
[
"Mallik",
"Shubhashis",
""
],
[
"Narain",
"Gaurav",
""
]
] |
In this paper, we delve into the gravitational path integral of Gauss-Bonnet gravity in four spacetime dimensions, in the mini-superspace approximation. Our primary focus lies in investigating the transition amplitude between distinct boundary configurations. Of particular interest is the case of Robin boundary conditions, known to lead to a stable Universe in Einstein-Hilbert gravity, alongside Neumann boundary conditions. To ensure a consistent variational problem, we supplement the bulk action with suitable surface terms. This study leads us to compute the necessary surface terms required for Gauss-Bonnet gravity with the Robin boundary condition, which wasn't known earlier. Thereafter, we perform an exact computation of the transition amplitude. Through $\hbar\to0$ analysis, we discover that the Gauss-Bonnet gravity inherently favors the initial configuration, aligning with the Hartle-Hawking no-boundary proposal. Remarkably, as the Universe expands, it undergoes a transition from the Euclidean (imaginary time) to the Lorentzian signature (real time). To further reinforce our findings, we employ a saddle point analysis utilizing the Picard-Lefschetz methods. The saddle point analysis allows us to find the initial configurations which lead to Hartle-Hawking no-boundary Universe that agrees with the exact computations. Our study concludes that for positive Gauss-Bonnet coupling, initial configurations corresponding to the Hartle-Hawking no-boundary Universe gives dominant contribution in the gravitational path-integral.
|
gr-qc/0211028
|
Thomas W. Baumgarte
|
Thomas W. Baumgarte and Stuart L. Shapiro
|
Numerical Relativity and Compact Binaries
|
122 pages, 19 figures; review article to appear in Physics Reports
|
Phys.Rept.376:41-131,2003
|
10.1016/S0370-1573(02)00537-9
| null |
gr-qc astro-ph hep-ph
| null |
Numerical relativity is the most promising tool for theoretically modeling
the inspiral and coalescence of neutron star and black hole binaries, which, in
turn, are among the most promising sources of gravitational radiation for
future detection by gravitational wave observatories. In this article we review
numerical relativity approaches to modeling compact binaries. Starting with a
brief introduction to the 3+1 decomposition of Einstein's equations, we discuss
important components of numerical relativity, including the initial data
problem, reformulations of Einstein's equations, coordinate conditions, and
strategies for locating and handling black holes on numerical grids. We focus
on those approaches which currently seem most relevant for the compact binary
problem. We then outline how these methods are used to model binary neutron
stars and black holes, and review the current status of inspiral and
coalescence simulations.
|
[
{
"created": "Thu, 7 Nov 2002 21:04:14 GMT",
"version": "v1"
}
] |
2009-07-09
|
[
[
"Baumgarte",
"Thomas W.",
""
],
[
"Shapiro",
"Stuart L.",
""
]
] |
Numerical relativity is the most promising tool for theoretically modeling the inspiral and coalescence of neutron star and black hole binaries, which, in turn, are among the most promising sources of gravitational radiation for future detection by gravitational wave observatories. In this article we review numerical relativity approaches to modeling compact binaries. Starting with a brief introduction to the 3+1 decomposition of Einstein's equations, we discuss important components of numerical relativity, including the initial data problem, reformulations of Einstein's equations, coordinate conditions, and strategies for locating and handling black holes on numerical grids. We focus on those approaches which currently seem most relevant for the compact binary problem. We then outline how these methods are used to model binary neutron stars and black holes, and review the current status of inspiral and coalescence simulations.
|
0810.2715
|
Mauricio Cataldo MC
|
Mauricio Cataldo, Pedro Labrana, Sergio del Campo, Juan Crisostomo and
Patricio Salgado
|
Evolving Lorentzian wormholes supported by phantom matter with constant
state parameters
|
9 pages, 2 figures, Accepted for publication in Phys. Rev. D
|
Phys.Rev.D78:104006,2008
|
10.1103/PhysRevD.78.104006
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper we study the possibility of sustaining an evolving wormhole via
exotic matter made out of phantom energy. We show that this exotic source can
support the existence of evolving wormhole spacetimes. Explicitly, a family of
evolving Lorentzian wormholes conformally related to another family of
zero-tidal force static wormhole geometries is found in Einstein gravity.
Contrary to the standard wormhole approach, where first a convenient geometry
is fixed and then the matter distribution is derived, we follow the
conventional approach for finding solutions in theoretical cosmology. We derive
an analytical evolving wormhole geometry by supposing that the radial tension
(which is negative to the radial pressure) and the pressure measured in the
tangential directions have barotropic equations of state with constant state
parameters. At spatial infinity this evolving wormhole, supported by this
anisotropic matter, is asymptotically flat, and its slices $t=$ constant are
spaces of constant curvature. During its evolution the shape of the wormhole
expands with constant velocity, i.e without acceleration or deceleration, since
the scale factor has strictly a linear evolution.
|
[
{
"created": "Wed, 15 Oct 2008 14:53:52 GMT",
"version": "v1"
}
] |
2008-11-26
|
[
[
"Cataldo",
"Mauricio",
""
],
[
"Labrana",
"Pedro",
""
],
[
"del Campo",
"Sergio",
""
],
[
"Crisostomo",
"Juan",
""
],
[
"Salgado",
"Patricio",
""
]
] |
In this paper we study the possibility of sustaining an evolving wormhole via exotic matter made out of phantom energy. We show that this exotic source can support the existence of evolving wormhole spacetimes. Explicitly, a family of evolving Lorentzian wormholes conformally related to another family of zero-tidal force static wormhole geometries is found in Einstein gravity. Contrary to the standard wormhole approach, where first a convenient geometry is fixed and then the matter distribution is derived, we follow the conventional approach for finding solutions in theoretical cosmology. We derive an analytical evolving wormhole geometry by supposing that the radial tension (which is negative to the radial pressure) and the pressure measured in the tangential directions have barotropic equations of state with constant state parameters. At spatial infinity this evolving wormhole, supported by this anisotropic matter, is asymptotically flat, and its slices $t=$ constant are spaces of constant curvature. During its evolution the shape of the wormhole expands with constant velocity, i.e without acceleration or deceleration, since the scale factor has strictly a linear evolution.
|
1902.00825
|
Fabi\'an Villalba
|
F. D. Villalba and P. Bargue\~no
|
Quasilocal Smarr relations for static black holes
|
12 pages, 1 figure. Accepted for publication in Physical Review D
|
Phys. Rev. D 99, 044021 (2019)
|
10.1103/PhysRevD.99.044021
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Generalized Smarr relations in terms of quasilocal variables are obtained for
Schwarzschild and Reissner-Nordstr\"om black holes. The approach is based on
gravitational path integrals with finite boundaries on which, following Brown
and York, thermodynamic variables are identified through a Hamilton-Jacobi
analysis of the action. The resulting expressions allow us to construct the
relation between the quasilocal energy obtained in this setting and the Komar
and Misner-Sharp energies, which are regarded as thermodynamical internal
energy in other approaches. The quasilocal Smarr relation is obtained through
scaling arguments, and terms evaluated in the external boundary and the horizon
are present. By considering some properties of the metric, it is shown that
this quasilocal Smarr relation can be regarded as a thermodynamical realization
of Einstein equations. The approach is suitable to be generalized to any
spherically symmetric metric.
|
[
{
"created": "Sun, 3 Feb 2019 01:25:32 GMT",
"version": "v1"
}
] |
2019-02-20
|
[
[
"Villalba",
"F. D.",
""
],
[
"Bargueño",
"P.",
""
]
] |
Generalized Smarr relations in terms of quasilocal variables are obtained for Schwarzschild and Reissner-Nordstr\"om black holes. The approach is based on gravitational path integrals with finite boundaries on which, following Brown and York, thermodynamic variables are identified through a Hamilton-Jacobi analysis of the action. The resulting expressions allow us to construct the relation between the quasilocal energy obtained in this setting and the Komar and Misner-Sharp energies, which are regarded as thermodynamical internal energy in other approaches. The quasilocal Smarr relation is obtained through scaling arguments, and terms evaluated in the external boundary and the horizon are present. By considering some properties of the metric, it is shown that this quasilocal Smarr relation can be regarded as a thermodynamical realization of Einstein equations. The approach is suitable to be generalized to any spherically symmetric metric.
|
gr-qc/0408057
|
Dr. Anirudh Pradhan
|
Anirudh Pradhan, Kashika Srivastava, Amrit Lal Ahuja
|
Nonsingular Spherical Models with a Variable Cosmological term
|
19 pages, 6 figures, submitted to Fizika B (Zagreb)
|
Fizika B16:141-158,2007
| null | null |
gr-qc
| null |
Exact solutions of the Einstein's field equations describing a spherically
symmetric cosmological model without a big bang or any other kind of
singularity recently obtained by Dadhich and Patel (2000) are revisited. The
matter content of the model is a shear-free perfect fluid with isotropic
pressure and a radial heat flux. Three different exact solutions are obtained
for both perfect fluid and fluid with bulk viscosity. It turns out that the
cosmological rerm $\Lambda(t)$ is a decreasing function of time, which is
consistent with recent observations of type Ia supernovae.
|
[
{
"created": "Wed, 18 Aug 2004 10:07:45 GMT",
"version": "v1"
},
{
"created": "Fri, 9 Mar 2007 07:00:28 GMT",
"version": "v2"
}
] |
2010-11-19
|
[
[
"Pradhan",
"Anirudh",
""
],
[
"Srivastava",
"Kashika",
""
],
[
"Ahuja",
"Amrit Lal",
""
]
] |
Exact solutions of the Einstein's field equations describing a spherically symmetric cosmological model without a big bang or any other kind of singularity recently obtained by Dadhich and Patel (2000) are revisited. The matter content of the model is a shear-free perfect fluid with isotropic pressure and a radial heat flux. Three different exact solutions are obtained for both perfect fluid and fluid with bulk viscosity. It turns out that the cosmological rerm $\Lambda(t)$ is a decreasing function of time, which is consistent with recent observations of type Ia supernovae.
|
2007.03835
|
Nomaan X
|
Joachim Kambor and Nomaan X
|
Manifold Properties from Causal Sets using Chains
|
30 pages, 12 figures
| null |
10.1088/1361-6382/abc8c9
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study the utility of chains defined on causal sets in estimating continuum
properties like the curvature, the proper time and the spacetime dimension
through a numerical analysis. In particular, we show that in $\text{dS}_2$ and
$\text{FLRW}_3$ spacetimes the formalism of arXiv:1212.0631 with slight
modifications gives the right continuum properties. We also discuss a possible
test of manifoldlikeness using this formalism by considering two models of
non-manifoldlike causal sets. This is a part of a broader idea of the
geometrical reconstruction of continuum properties given a discrete sub
structure, in this case the causal set.
|
[
{
"created": "Wed, 8 Jul 2020 01:07:08 GMT",
"version": "v1"
},
{
"created": "Thu, 1 Oct 2020 10:58:26 GMT",
"version": "v2"
},
{
"created": "Tue, 10 Nov 2020 06:16:58 GMT",
"version": "v3"
}
] |
2020-11-11
|
[
[
"Kambor",
"Joachim",
""
],
[
"X",
"Nomaan",
""
]
] |
We study the utility of chains defined on causal sets in estimating continuum properties like the curvature, the proper time and the spacetime dimension through a numerical analysis. In particular, we show that in $\text{dS}_2$ and $\text{FLRW}_3$ spacetimes the formalism of arXiv:1212.0631 with slight modifications gives the right continuum properties. We also discuss a possible test of manifoldlikeness using this formalism by considering two models of non-manifoldlike causal sets. This is a part of a broader idea of the geometrical reconstruction of continuum properties given a discrete sub structure, in this case the causal set.
|
gr-qc/0309059
|
Laszlo A. Gergely
|
L\'aszl\'o \'A Gergely
|
A homogeneous brane-world universe
| null |
Class.Quant.Grav. 21 (2004) 935-940
|
10.1088/0264-9381/21/4/013
| null |
gr-qc astro-ph hep-th
| null |
A homogeneous, Kantowski-Sachs type, bouncing brane-world universe is
presented. The bulk has a positive cosmological constant and the Killing
algebra $so(1,3)\oplus so(3)$. The totality of the source terms of the
effective Einstein equation combine to a solid with different radial and
tangential pressures.
|
[
{
"created": "Thu, 11 Sep 2003 17:06:59 GMT",
"version": "v1"
}
] |
2016-08-16
|
[
[
"Gergely",
"László Á",
""
]
] |
A homogeneous, Kantowski-Sachs type, bouncing brane-world universe is presented. The bulk has a positive cosmological constant and the Killing algebra $so(1,3)\oplus so(3)$. The totality of the source terms of the effective Einstein equation combine to a solid with different radial and tangential pressures.
|
1303.7038
|
Jorge Mastache
|
Jorge Mastache, Axel de la Macorra
|
Extra relativistic degrees of freedom without extra particles using
Planck data
|
9 pages, 7 figures, 2 Tables
| null |
10.1103/PhysRevD.88.043506
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A recent number of analysis of cosmological data have shown indications for
the presence of extra radiation beyond the standard model at equality and
nucleosynthesis epoch, which has been usually interpreted as an effective
number of neutrinos, Neff > 3.046. In this work we establish the theoretical
basis for a particle physics-motivated model (Bound Dark Matter, BDM) which
explain the need of extra radiation. The BDM model describes dark matter
particles which are relativistic at a scale below a < ac, these particles
acquire mass with an initial velocity, vc, at scales a > ac due to
non-perturbative methods, as protons and neutrons do, this process is described
by a time dependent equation of state, w_bdm(a). Owing to this behavior the
amount of extra radiation change as a function of the scale factor, this entail
that the extra relativistic degrees of freedom Nex may also vary as a function
of the scale factor. This is favored by data at CMB and BBN epochs. We compute
the range of values of the BDM model parameters, xc = ac*vc, that explain the
values obtained for the 4He at BBN and Neff at equality. Combining different
analysis we compute the value xc = 4.13x10^{-5} and vc = 0.37. We conclude that
we can account for the apparent extra neutrino degrees of freedom Nex using a
phase transition in the dark matter with a time dependent equation of state
with no need for introducing extra relativistic particles.
|
[
{
"created": "Thu, 28 Mar 2013 04:53:44 GMT",
"version": "v1"
},
{
"created": "Mon, 29 Apr 2013 20:16:29 GMT",
"version": "v2"
}
] |
2013-08-14
|
[
[
"Mastache",
"Jorge",
""
],
[
"de la Macorra",
"Axel",
""
]
] |
A recent number of analysis of cosmological data have shown indications for the presence of extra radiation beyond the standard model at equality and nucleosynthesis epoch, which has been usually interpreted as an effective number of neutrinos, Neff > 3.046. In this work we establish the theoretical basis for a particle physics-motivated model (Bound Dark Matter, BDM) which explain the need of extra radiation. The BDM model describes dark matter particles which are relativistic at a scale below a < ac, these particles acquire mass with an initial velocity, vc, at scales a > ac due to non-perturbative methods, as protons and neutrons do, this process is described by a time dependent equation of state, w_bdm(a). Owing to this behavior the amount of extra radiation change as a function of the scale factor, this entail that the extra relativistic degrees of freedom Nex may also vary as a function of the scale factor. This is favored by data at CMB and BBN epochs. We compute the range of values of the BDM model parameters, xc = ac*vc, that explain the values obtained for the 4He at BBN and Neff at equality. Combining different analysis we compute the value xc = 4.13x10^{-5} and vc = 0.37. We conclude that we can account for the apparent extra neutrino degrees of freedom Nex using a phase transition in the dark matter with a time dependent equation of state with no need for introducing extra relativistic particles.
|
1304.2228
|
Jan Steinhoff
|
Sayan Chakrabarti, T\'erence Delsate, Jan Steinhoff
|
New perspectives on neutron star and black hole spectroscopy and dynamic
tides
|
RevTeX, 18 pages, 1 figure, v2: added references, v3: corrected
integration constants in Eq. (12), neutron star case essentially unaffected
| null | null | null |
gr-qc astro-ph.SR hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We elaborate on a powerful tidal interaction formalism where the multipole
dynamics is kept generic and encoded in a linear response function. This
response function is the gravitational counterpart of the atomic spectrum and
can become of similar importance with the rise of gravitational wave astronomy.
We find that the internal dynamics of nonrotating neutron stars admit a
harmonic oscillator formulation yielding a simple interpretation of tides. A
preliminary investigation of the black holes case is given. Our results fill
the gap between Love numbers and dynamic tides.
|
[
{
"created": "Mon, 8 Apr 2013 15:04:33 GMT",
"version": "v1"
},
{
"created": "Mon, 15 Apr 2013 19:58:58 GMT",
"version": "v2"
},
{
"created": "Tue, 21 May 2013 14:30:39 GMT",
"version": "v3"
}
] |
2013-05-22
|
[
[
"Chakrabarti",
"Sayan",
""
],
[
"Delsate",
"Térence",
""
],
[
"Steinhoff",
"Jan",
""
]
] |
We elaborate on a powerful tidal interaction formalism where the multipole dynamics is kept generic and encoded in a linear response function. This response function is the gravitational counterpart of the atomic spectrum and can become of similar importance with the rise of gravitational wave astronomy. We find that the internal dynamics of nonrotating neutron stars admit a harmonic oscillator formulation yielding a simple interpretation of tides. A preliminary investigation of the black holes case is given. Our results fill the gap between Love numbers and dynamic tides.
|
gr-qc/0703009
|
Frans Klinkhamer
|
F.R. Klinkhamer
|
Fundamental length scale of quantum spacetime foam
|
10 pages with revtex4, v5: published version
|
JETPLett.86:73-77,2007
|
10.1134/S0021364007140019
|
KA-TP-03-2007
|
gr-qc hep-ph hep-th
| null |
It is argued that the fundamental length scale for the quantum dynamics of
spacetime need not be equal to the Planck length. Possibly, this new length
scale is related to a nonvanishing cosmological constant or vacuum energy
density.
|
[
{
"created": "Thu, 1 Mar 2007 19:43:09 GMT",
"version": "v1"
},
{
"created": "Tue, 6 Mar 2007 15:51:59 GMT",
"version": "v2"
},
{
"created": "Wed, 30 May 2007 18:50:05 GMT",
"version": "v3"
},
{
"created": "Thu, 21 Jun 2007 15:20:02 GMT",
"version": "v4"
},
{
"created": "Wed, 29 Aug 2007 15:44:47 GMT",
"version": "v5"
}
] |
2008-11-26
|
[
[
"Klinkhamer",
"F. R.",
""
]
] |
It is argued that the fundamental length scale for the quantum dynamics of spacetime need not be equal to the Planck length. Possibly, this new length scale is related to a nonvanishing cosmological constant or vacuum energy density.
|
1610.08135
|
Kai Lin
|
Kai Lin and Wei-Liang Qian
|
A Matrix Method for Quasinormal Modes: Schwarzschild Black Holes in
Asymptotically Flat and (Anti-) de Sitter Spacetimes
|
The program is attached in the ancillary files on the arXiv server
|
Class. Quantum Grav. 34 (2017) 095004 (13pp)
|
10.1088/1361-6382/aa6643
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this work, we study the quasinormal modes of Schwarzschild and
Schwarzschild (Anti-) de Sitter black holes by a matrix method. The proposed
method involves discretizing the master field equation and expressing it in
form of a homogeneous system of linear algebraic equations. The resulting
homogeneous matrix equation furnishes a non-standard eigenvalue problem, which
can then be solved numerically to obtain the quasinormal frequencies. A key
feature of the present approach is that the discretization of the wave function
and its derivatives are made to be independent of any specific metric through
coordinate transformation. In many cases, it can be carried out beforehand
which in turn improves the efficiency and facilitates the numerical
implementation. We also analyze the precision and efficiency of the present
method as well as compare the results to those obtained by different
approaches.
|
[
{
"created": "Wed, 26 Oct 2016 01:05:24 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Nov 2016 18:21:43 GMT",
"version": "v2"
},
{
"created": "Tue, 28 Feb 2017 20:46:00 GMT",
"version": "v3"
},
{
"created": "Sat, 1 Apr 2017 18:07:34 GMT",
"version": "v4"
}
] |
2017-04-04
|
[
[
"Lin",
"Kai",
""
],
[
"Qian",
"Wei-Liang",
""
]
] |
In this work, we study the quasinormal modes of Schwarzschild and Schwarzschild (Anti-) de Sitter black holes by a matrix method. The proposed method involves discretizing the master field equation and expressing it in form of a homogeneous system of linear algebraic equations. The resulting homogeneous matrix equation furnishes a non-standard eigenvalue problem, which can then be solved numerically to obtain the quasinormal frequencies. A key feature of the present approach is that the discretization of the wave function and its derivatives are made to be independent of any specific metric through coordinate transformation. In many cases, it can be carried out beforehand which in turn improves the efficiency and facilitates the numerical implementation. We also analyze the precision and efficiency of the present method as well as compare the results to those obtained by different approaches.
|
2305.18522
|
Kyriakos Destounis Dr.
|
Kyriakos Destounis and Kostas D. Kokkotas
|
Slowly-rotating compact objects: the nonintegrability of Hartle-Thorne
particle geodesics
|
15 pages, 5 figures, minor revision, abstract abridged due to arxiv
limitations, accepted for publication in General Relativity and Gravitation
|
Gen Relativ Gravit 55, 123 (2023)
|
10.1007/s10714-023-03170-z
| null |
gr-qc astro-ph.HE hep-th nlin.CD
|
http://creativecommons.org/licenses/by/4.0/
|
X-ray astronomy provides information regarding the electromagnetic emission
of active galactic nuclei and X-ray binaries. These events provide details
regarding the astrophysical environment of black holes and stars, and help us
understand gamma-ray bursts. They produce estimates for the maximum mass of
neutron stars and eventually will contribute to the discovery of their equation
of state. Thus, it is crucial to study them in order to enhance the yield of
X-ray astronomy when combined with multimessenger astrophysics. An exact
solution of the field equations does not exist for rotating neutron stars.
There exist a variety of approximate solutions for compact objects that may
characterize relativistic stars. The most studied approximation is the
Hartle-Thorne metric that represents slowly-rotating compact objects, like
massive stars, white dwarfs and neutron stars. Recent investigations of photon
orbits and shadows of such metric revealed that it exhibits chaos close to
resonances. Here, we thoroughly investigate particle orbits around the
Hartle-Thorne spacetime up to second order in rotation. We perform an
exhaustive analysis of bound motion, by varying all parameters involved in the
system. We demonstrate that chaotic regions, known as Birkhoff islands, form
around resonances, where the ratio of the radial and polar frequency of
geodesics, known as the rotation number, is shared throughout the island. This
leads to the formation of plateaus in rotation curves during the most prominent
$2/3$ resonance, which confirms that generic geodesics are nonintegrable. We
measure their width and show how each parameter affects it. The
nonintegrability of Hartle-Thorne metric may affect quasiperiodic oscillations
of low-mass X-ray binaries, when chaos is taken into account, and might
potentially improve estimates of mass, angular momentum and multipole moments
of astrophysical compact objects.
|
[
{
"created": "Mon, 29 May 2023 18:00:03 GMT",
"version": "v1"
},
{
"created": "Fri, 13 Oct 2023 14:36:19 GMT",
"version": "v2"
}
] |
2023-11-01
|
[
[
"Destounis",
"Kyriakos",
""
],
[
"Kokkotas",
"Kostas D.",
""
]
] |
X-ray astronomy provides information regarding the electromagnetic emission of active galactic nuclei and X-ray binaries. These events provide details regarding the astrophysical environment of black holes and stars, and help us understand gamma-ray bursts. They produce estimates for the maximum mass of neutron stars and eventually will contribute to the discovery of their equation of state. Thus, it is crucial to study them in order to enhance the yield of X-ray astronomy when combined with multimessenger astrophysics. An exact solution of the field equations does not exist for rotating neutron stars. There exist a variety of approximate solutions for compact objects that may characterize relativistic stars. The most studied approximation is the Hartle-Thorne metric that represents slowly-rotating compact objects, like massive stars, white dwarfs and neutron stars. Recent investigations of photon orbits and shadows of such metric revealed that it exhibits chaos close to resonances. Here, we thoroughly investigate particle orbits around the Hartle-Thorne spacetime up to second order in rotation. We perform an exhaustive analysis of bound motion, by varying all parameters involved in the system. We demonstrate that chaotic regions, known as Birkhoff islands, form around resonances, where the ratio of the radial and polar frequency of geodesics, known as the rotation number, is shared throughout the island. This leads to the formation of plateaus in rotation curves during the most prominent $2/3$ resonance, which confirms that generic geodesics are nonintegrable. We measure their width and show how each parameter affects it. The nonintegrability of Hartle-Thorne metric may affect quasiperiodic oscillations of low-mass X-ray binaries, when chaos is taken into account, and might potentially improve estimates of mass, angular momentum and multipole moments of astrophysical compact objects.
|
1908.00509
|
Ozgur Delice
|
M. Haluk Se\c{c}uk, \"Ozg\"ur Delice
|
Bending of Light from Reissner-Nordstr\"om-de Sitter-Monopole Black Hole
|
v2: 10 pages, 2 figures, matches the published version
|
Eur. Phys. J. Plus, 135 7 (2020) 610
|
10.1140/epjp/s13360-020-00551-0
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study light deflection from a Reissner-Nordstr\"om-de Sitter black hole in
the gravitational monopole background. We first calculate the orbit equation
and the contribution of the monopole and black hole parameters to the
deflection angle up to second-order for the vanishing cosmological constant
case using the Rindler-Ishak method. We also obtain the contribution of the
cosmological constant to light deflection in this geometry in the weak field
limit using the same method.
|
[
{
"created": "Thu, 1 Aug 2019 17:07:03 GMT",
"version": "v1"
},
{
"created": "Mon, 3 Aug 2020 21:19:43 GMT",
"version": "v2"
}
] |
2020-08-05
|
[
[
"Seçuk",
"M. Haluk",
""
],
[
"Delice",
"Özgür",
""
]
] |
We study light deflection from a Reissner-Nordstr\"om-de Sitter black hole in the gravitational monopole background. We first calculate the orbit equation and the contribution of the monopole and black hole parameters to the deflection angle up to second-order for the vanishing cosmological constant case using the Rindler-Ishak method. We also obtain the contribution of the cosmological constant to light deflection in this geometry in the weak field limit using the same method.
|
2012.00002
|
Mohammad Reza Setare
|
M. R. Setare and S. N. Sajadi
|
Phase Transition Between Flat Space Cosmology and Hot Flat Spacetimes in
GMMG and EGMG Models
|
13 pages, typos corrected, main results and conclusion unchanged,
reference and paragraph added
| null |
10.1088/1361-6382/ac03f7
| null |
gr-qc hep-th
|
http://creativecommons.org/licenses/by/4.0/
|
Flat Space Cosmology (FSC) spacetimes are exact solutions of 3D gravity
theories. In this work, we study phase transition between FSC spacetimes and
Hot Flat Spacetimes (HFS) in general minimal massive gravity and exotic general
massive gravity. We show that similar to topological massive gravity the
tunneling occurs between two spacetimes by comparing their free energies. We
also obtain the corrections to the Bekenstein-Hawking entropy, and its effect
on the phase transition is studied.
|
[
{
"created": "Sat, 28 Nov 2020 13:30:27 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Feb 2021 06:29:03 GMT",
"version": "v2"
}
] |
2021-07-07
|
[
[
"Setare",
"M. R.",
""
],
[
"Sajadi",
"S. N.",
""
]
] |
Flat Space Cosmology (FSC) spacetimes are exact solutions of 3D gravity theories. In this work, we study phase transition between FSC spacetimes and Hot Flat Spacetimes (HFS) in general minimal massive gravity and exotic general massive gravity. We show that similar to topological massive gravity the tunneling occurs between two spacetimes by comparing their free energies. We also obtain the corrections to the Bekenstein-Hawking entropy, and its effect on the phase transition is studied.
|
gr-qc/0204034
|
J. Mark Heinzle
|
J. Mark Heinzle
|
(In)finiteness of Spherically Symmetric Static Perfect Fluids
| null |
Class.Quant.Grav. 19 (2002) 2835-2852
|
10.1088/0264-9381/19/11/307
| null |
gr-qc
| null |
This work is concerned with the finiteness problem for static, spherically
symmetric perfect fluids in both Newtonian Gravity and General Relativity. We
derive criteria on the barotropic equation of state guaranteeing that the
corresponding perfect fluid solutions possess finite/infinite extent. In the
Newtonian case, for the large class of monotonic equations of state, and in
General Relativity we improve earlier results.
|
[
{
"created": "Mon, 8 Apr 2002 16:28:36 GMT",
"version": "v1"
}
] |
2009-11-07
|
[
[
"Heinzle",
"J. Mark",
""
]
] |
This work is concerned with the finiteness problem for static, spherically symmetric perfect fluids in both Newtonian Gravity and General Relativity. We derive criteria on the barotropic equation of state guaranteeing that the corresponding perfect fluid solutions possess finite/infinite extent. In the Newtonian case, for the large class of monotonic equations of state, and in General Relativity we improve earlier results.
|
2309.00873
|
Theodoros Nakas
|
Theodoros Nakas, Thomas D. Pappas, Zden\v{e}k Stuchl\'ik
|
Bridging Dimensions: General Embedding Algorithm and Field-Theory
Reconstruction in 5D Braneworld Models
|
5 pages, 1 figure, extended discussion, references added, version to
match the one published in Phys. Rev. D
| null |
10.1103/PhysRevD.109.L041501
| null |
gr-qc hep-th
|
http://creativecommons.org/licenses/by-nc-sa/4.0/
|
We develop a general algorithm that enables the consistent embedding of any
four-dimensional static and spherically symmetric geometry into any
five-dimensional single-brane braneworld model, characterized by an injective
and nonsingular warp factor. Furthermore, we supplement the algorithm by
introducing a method that allows one to, in principle, reconstruct 5D field
theories that support the aforementioned geometries. This approach is based on
a conformal transformation of the metric with the conformal factor being
identified with the warp factor of the bulk geometry. The reconstructed
theories depend solely on the induced brane geometry, since the warp factor is
model-independently represented by a scalar field in the Lagrangian density. As
a first application of our reconstruction method, we present for the first time
a complete theory that supports the five-dimensional brane-localized extension
of the Schwarzschild black hole, for any warp factor. The same method is
subsequently utilized to illustrate the process of coherently embedding a de
Sitter brane in braneworld models.
|
[
{
"created": "Sat, 2 Sep 2023 09:13:10 GMT",
"version": "v1"
},
{
"created": "Thu, 22 Feb 2024 09:23:44 GMT",
"version": "v2"
}
] |
2024-02-23
|
[
[
"Nakas",
"Theodoros",
""
],
[
"Pappas",
"Thomas D.",
""
],
[
"Stuchlík",
"Zdeněk",
""
]
] |
We develop a general algorithm that enables the consistent embedding of any four-dimensional static and spherically symmetric geometry into any five-dimensional single-brane braneworld model, characterized by an injective and nonsingular warp factor. Furthermore, we supplement the algorithm by introducing a method that allows one to, in principle, reconstruct 5D field theories that support the aforementioned geometries. This approach is based on a conformal transformation of the metric with the conformal factor being identified with the warp factor of the bulk geometry. The reconstructed theories depend solely on the induced brane geometry, since the warp factor is model-independently represented by a scalar field in the Lagrangian density. As a first application of our reconstruction method, we present for the first time a complete theory that supports the five-dimensional brane-localized extension of the Schwarzschild black hole, for any warp factor. The same method is subsequently utilized to illustrate the process of coherently embedding a de Sitter brane in braneworld models.
|
2005.02208
|
Messias De Brito Cruz
|
M. B. Cruz, F. A. Brito and C. A. S. Silva
|
Polar gravitational perturbations and quasinormal modes of a loop
quantum gravity black hole
|
16 pages, 5 figures. This manuscript has been accepted for
publication as a Regular Article in Physical Review D
|
Phys. Rev. D 102, 044063 (2020)
|
10.1103/PhysRevD.102.044063
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this work, we have calculated the polar gravitational quasinormal modes
for a quantum corrected black hole model, that arises in the context of Loop
Quantum Gravity, known as Self-Dual Black Hole. In this way, we have calculated
the characteristic frequencies using the WKB approach, where we can verify a
strong dependence with the Loop Quantum Gravity parameters. At the same time we
check that the Self-Dual Black Hole is stable under polar gravitational
perturbations, we can also verify that the spectrum of the polar quasinormal
modes differs from the axial one \cite{Cruz:2015bcj}. Such a result tells us
that isospectrality is broken in the context of Self Dual Black Holes.
|
[
{
"created": "Mon, 4 May 2020 17:39:47 GMT",
"version": "v1"
},
{
"created": "Sun, 26 Jul 2020 14:46:59 GMT",
"version": "v2"
},
{
"created": "Tue, 11 Aug 2020 17:04:03 GMT",
"version": "v3"
}
] |
2020-09-09
|
[
[
"Cruz",
"M. B.",
""
],
[
"Brito",
"F. A.",
""
],
[
"Silva",
"C. A. S.",
""
]
] |
In this work, we have calculated the polar gravitational quasinormal modes for a quantum corrected black hole model, that arises in the context of Loop Quantum Gravity, known as Self-Dual Black Hole. In this way, we have calculated the characteristic frequencies using the WKB approach, where we can verify a strong dependence with the Loop Quantum Gravity parameters. At the same time we check that the Self-Dual Black Hole is stable under polar gravitational perturbations, we can also verify that the spectrum of the polar quasinormal modes differs from the axial one \cite{Cruz:2015bcj}. Such a result tells us that isospectrality is broken in the context of Self Dual Black Holes.
|
2003.07649
|
Peter Horvathy
|
K. Andrzejewski, N. Dimakis, M. Elbistan, P. A. Horvathy, P. Kosinski,
P.-M. Zhang
|
Conformal symmetries and integrals of the motion in pp waves with
external electromagnetic fields
|
Published as Annals of Physics 418 (2020) 168180. 39 pages, 1 figure
| null |
10.1016/j.aop.2020.168180
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The integrals of the motion associated with conformal Killing vectors of a
curved space-time with an additional electromagnetic background are studied for
massive particles. They involve a new term which might be non-local. The
difficulty disappears for pp-waves, for which explicit, local conserved charges
are found. Alternatively, the mass can be taken into account by "distorting"
the conformal Killing vectors. The relation of these non-point symmetries to
the charges is analysed both in the Lagrangian and Hamiltonian approaches, as
well as in the framework of Eisenhart-Duval lift.
|
[
{
"created": "Tue, 17 Mar 2020 11:28:46 GMT",
"version": "v1"
},
{
"created": "Fri, 1 May 2020 16:33:46 GMT",
"version": "v2"
}
] |
2020-05-04
|
[
[
"Andrzejewski",
"K.",
""
],
[
"Dimakis",
"N.",
""
],
[
"Elbistan",
"M.",
""
],
[
"Horvathy",
"P. A.",
""
],
[
"Kosinski",
"P.",
""
],
[
"Zhang",
"P. -M.",
""
]
] |
The integrals of the motion associated with conformal Killing vectors of a curved space-time with an additional electromagnetic background are studied for massive particles. They involve a new term which might be non-local. The difficulty disappears for pp-waves, for which explicit, local conserved charges are found. Alternatively, the mass can be taken into account by "distorting" the conformal Killing vectors. The relation of these non-point symmetries to the charges is analysed both in the Lagrangian and Hamiltonian approaches, as well as in the framework of Eisenhart-Duval lift.
|
1911.02299
|
Albert Huber
|
Albert Huber
|
The gravitational Field of a massless Particle on the Horizon of a
stationary Black Hole
|
30 pages, no figures; published in CQG
|
Classical and Quantum Gravity, 2021
|
10.1088/1361-6382/abe881
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this work, the field of a gravitational shockwave generated by a massless
point-like particle is calculated at the event horizon of a stationary
Kerr-Newman black hole. Using the geometric framework of generalized
Kerr-Schild deformations in combination with the spin-coefficient formalism of
Newman and Penrose, it is shown that the field equations of the theory, at the
event horizon of the black hole, can be reduced to a single linear ordinary
differential equation for the so-called profile function of the geometry. This
differential relation is solved exactly. Based on the results obtained, a
physical interpretation is given for the found shockwave spacetime, and it is
clarified how these results lead back to those of previous works on the
subject, which deal with the much simpler cases of gravitational shockwaves in
static black hole backgrounds.
|
[
{
"created": "Wed, 6 Nov 2019 10:45:07 GMT",
"version": "v1"
},
{
"created": "Mon, 29 Mar 2021 17:56:05 GMT",
"version": "v2"
}
] |
2021-03-30
|
[
[
"Huber",
"Albert",
""
]
] |
In this work, the field of a gravitational shockwave generated by a massless point-like particle is calculated at the event horizon of a stationary Kerr-Newman black hole. Using the geometric framework of generalized Kerr-Schild deformations in combination with the spin-coefficient formalism of Newman and Penrose, it is shown that the field equations of the theory, at the event horizon of the black hole, can be reduced to a single linear ordinary differential equation for the so-called profile function of the geometry. This differential relation is solved exactly. Based on the results obtained, a physical interpretation is given for the found shockwave spacetime, and it is clarified how these results lead back to those of previous works on the subject, which deal with the much simpler cases of gravitational shockwaves in static black hole backgrounds.
|
2405.21072
|
Philip Lynch PhD
|
Philip Lynch, Vojt\v{e}ch Witzany, Maarten van de Meent, Niels
Warburton
|
Fast inspirals and the treatment of orbital resonances
|
48 pages, 11 figures
| null | null | null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
Extreme mass ratio inspirals (EMRIs), where a compact object orbits a massive
black hole, are a key source of gravitational waves for the future Laser
Interferometer Space Antenna (LISA). Due to their small mass ratio, ($\epsilon
\sim 10^{-4}$--$10^{-7}$), the binary evolves slowly and EMRI signals will be
in-band for years. Additionally, astrophysical EMRIs are expected to have
complex dynamics featuring both spin-precession and eccentricity. A standard
approach to modelling these inspirals is via the method of osculating geodesics
(OG) which we employ along with a toy model for the gravitational self-force.
Using this method requires resolving tens of thousands radial and polar orbital
librations over the long duration of the signal which makes the inspiral
trajectory expensive to compute. In this work we accelerate these calculations
by employing Near-Identity (averaging) Transformations. However, this averaging
technique breaks down at orbital resonances where the radial and polar
frequencies are an integer ratio of each other. Thus, we switch to a partial
averaging transformation in the vicinity of the resonance where the dynamics
are characterised by the slow evolution of the so-called "resonant phase".
Additionally, we develop an optimal switching criterion to minimise the
computation time while maximising accuracy. We find the error in the waveform
phase is improved from $\mathcal{O}(\epsilon^{-1/2})$ in the fully averaged
scheme to $\mathcal{O}(\epsilon^{4/7})$ in the switching scheme. At the same
time, this scheme improves the scaling of the computation time from being
inversely proportional to $\epsilon$ using OG, to a very weak scaling with
$\epsilon$. This results in a speed-up of at least two orders of magnitude for
LISA EMRIs with room for further optimisation.
|
[
{
"created": "Fri, 31 May 2024 17:58:06 GMT",
"version": "v1"
}
] |
2024-06-03
|
[
[
"Lynch",
"Philip",
""
],
[
"Witzany",
"Vojtěch",
""
],
[
"van de Meent",
"Maarten",
""
],
[
"Warburton",
"Niels",
""
]
] |
Extreme mass ratio inspirals (EMRIs), where a compact object orbits a massive black hole, are a key source of gravitational waves for the future Laser Interferometer Space Antenna (LISA). Due to their small mass ratio, ($\epsilon \sim 10^{-4}$--$10^{-7}$), the binary evolves slowly and EMRI signals will be in-band for years. Additionally, astrophysical EMRIs are expected to have complex dynamics featuring both spin-precession and eccentricity. A standard approach to modelling these inspirals is via the method of osculating geodesics (OG) which we employ along with a toy model for the gravitational self-force. Using this method requires resolving tens of thousands radial and polar orbital librations over the long duration of the signal which makes the inspiral trajectory expensive to compute. In this work we accelerate these calculations by employing Near-Identity (averaging) Transformations. However, this averaging technique breaks down at orbital resonances where the radial and polar frequencies are an integer ratio of each other. Thus, we switch to a partial averaging transformation in the vicinity of the resonance where the dynamics are characterised by the slow evolution of the so-called "resonant phase". Additionally, we develop an optimal switching criterion to minimise the computation time while maximising accuracy. We find the error in the waveform phase is improved from $\mathcal{O}(\epsilon^{-1/2})$ in the fully averaged scheme to $\mathcal{O}(\epsilon^{4/7})$ in the switching scheme. At the same time, this scheme improves the scaling of the computation time from being inversely proportional to $\epsilon$ using OG, to a very weak scaling with $\epsilon$. This results in a speed-up of at least two orders of magnitude for LISA EMRIs with room for further optimisation.
|
2205.11650
|
Ronald Gamble Jr
|
Ronald S. Gamble Jr
|
Spin Tetrad Formalism Of Circular Polarization States In Relativistic
Jets
|
11 pages, 4 figures
| null | null | null |
gr-qc astro-ph.HE
|
http://creativecommons.org/licenses/by/4.0/
|
Relativistic jets from active galactic nuclei (AGN) have been of peak
interest in the high-energy astrophysics community for their uniquely dynamic
nature and incredible radiative power; emanating from supermassive black holes
and similarly accreting compact dense objects. An overall consensus on
relativistic jet formation states that accelerated outflow at high Lorentz
factors are generated by a complex relationship between the accretion disk of
the system and the frame-dragging effects of the rotating massive central
object. This paper will provide a basis for which circular polarization states,
defined using a spin tetrad formalism, contribute to a description for the
angular momentum flux in the jet emanating from the central engine. A
representation of the Kerr spacetime with positive cosmological constant
background is used in formulating the spin tetrad forms. A discussion on
unresolved problems in jet formation and how we can use multi-method
observations with polarimetry of AGN to direct future theoretical descriptions
will also be given.
|
[
{
"created": "Mon, 23 May 2022 22:04:41 GMT",
"version": "v1"
},
{
"created": "Thu, 30 Jun 2022 15:30:57 GMT",
"version": "v2"
},
{
"created": "Wed, 22 May 2024 20:38:23 GMT",
"version": "v3"
}
] |
2024-05-24
|
[
[
"Gamble",
"Ronald S.",
"Jr"
]
] |
Relativistic jets from active galactic nuclei (AGN) have been of peak interest in the high-energy astrophysics community for their uniquely dynamic nature and incredible radiative power; emanating from supermassive black holes and similarly accreting compact dense objects. An overall consensus on relativistic jet formation states that accelerated outflow at high Lorentz factors are generated by a complex relationship between the accretion disk of the system and the frame-dragging effects of the rotating massive central object. This paper will provide a basis for which circular polarization states, defined using a spin tetrad formalism, contribute to a description for the angular momentum flux in the jet emanating from the central engine. A representation of the Kerr spacetime with positive cosmological constant background is used in formulating the spin tetrad forms. A discussion on unresolved problems in jet formation and how we can use multi-method observations with polarimetry of AGN to direct future theoretical descriptions will also be given.
|
gr-qc/0004004
|
Jens C. Niemeyer
|
Jens C. Niemeyer, Raphael Bousso
|
The nonlinear evolution of de Sitter space instabilities
|
10 pages, 8 figures, to appear in PRD
|
Phys.Rev. D62 (2000) 023503
|
10.1103/PhysRevD.62.023503
| null |
gr-qc astro-ph
| null |
We investigate the quantum evolution of large black holes that nucleate
spontaneously in de Sitter space. By numerical computation in the s-wave and
one-loop approximations, we verify claims that such black holes can initially
"anti-evaporate" instead of shrink. We show, however, that this is a transitory
effect. It is followed by an evaporating phase, which we are able to trace
until the black holes are small enough to be treated as Schwarzschild. Under
generic perturbations, the nucleated geometry is shown to decay into a ring of
de Sitter regions connected by evaporating black holes. This confirms that de
Sitter space is globally unstable and fragments into disconnected daughter
universes.
|
[
{
"created": "Sat, 1 Apr 2000 21:58:48 GMT",
"version": "v1"
}
] |
2009-10-31
|
[
[
"Niemeyer",
"Jens C.",
""
],
[
"Bousso",
"Raphael",
""
]
] |
We investigate the quantum evolution of large black holes that nucleate spontaneously in de Sitter space. By numerical computation in the s-wave and one-loop approximations, we verify claims that such black holes can initially "anti-evaporate" instead of shrink. We show, however, that this is a transitory effect. It is followed by an evaporating phase, which we are able to trace until the black holes are small enough to be treated as Schwarzschild. Under generic perturbations, the nucleated geometry is shown to decay into a ring of de Sitter regions connected by evaporating black holes. This confirms that de Sitter space is globally unstable and fragments into disconnected daughter universes.
|
2311.07246
|
Wu Bofeng
|
Bofeng Wu and En-Wei Liang
|
Multipole expansion of the gravitational field in a general class of
fourth-order theories of gravity and the application in gyroscopic precession
|
46 pages,0 figure,accepted by JCAP
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A viable weak-field and slow-motion approximation method is constructed in
$F(R,R_{\mu\nu}R^{\mu\nu}, R_{\mu\nu\rho\sigma}R^{\mu\nu\rho\sigma})$ gravity,
a general class of fourth-order theories of gravity. By applying this method,
the metric, presented in the form of the multipole expansion, outside a
spatially compact source up to $1/c^3$ order is provided, and the closed-form
expressions for the source multipole moments are all presented explicitly. The
metric consists of the massless tensor part, the massive scalar part, and the
massive tensor part, where the former is exactly the metric in General
Relativity, and the latter two are the corrections to it. It is shown that the
corrections bear the Yukawa-like dependence on the two massive parameters and
predict the appearance of six additional sets of source multipole moments,
which indicates that up to $1/c^3$ order, there exist six degrees of freedom
beyond General Relativity within $F(R,R_{\mu\nu}R^{\mu\nu},
R_{\mu\nu\rho\sigma}R^{\mu\nu\rho\sigma})$ gravity. By means of the metric, for
a gyroscope moving around the source without experiencing any torque, the
multipole expansions of its spin's angular velocities of the Thomas precession,
the geodetic precession, and the Lense-Thirring precession are derived, and
from them, the corrections to the angular velocities of the three types of
precession in General Relativity can be read off. These results indicate that
differently from $f(R)$ or $f(R,\mathcal{G})$ gravity, the most salient feature
of the general $F(R,R_{\mu\nu}R^{\mu\nu},
R_{\mu\nu\rho\sigma}R^{\mu\nu\rho\sigma})$ gravity is that it gives the
nonvanishing correction to the gyroscopic spin's angular velocity of the
Lense-Thirring precession in General Relativity.
|
[
{
"created": "Mon, 13 Nov 2023 11:29:28 GMT",
"version": "v1"
},
{
"created": "Tue, 14 Nov 2023 11:30:47 GMT",
"version": "v2"
},
{
"created": "Thu, 16 Nov 2023 11:43:32 GMT",
"version": "v3"
},
{
"created": "Mon, 5 Feb 2024 13:22:14 GMT",
"version": "v4"
},
{
"created": "Tue, 30 Apr 2024 01:52:25 GMT",
"version": "v5"
}
] |
2024-05-01
|
[
[
"Wu",
"Bofeng",
""
],
[
"Liang",
"En-Wei",
""
]
] |
A viable weak-field and slow-motion approximation method is constructed in $F(R,R_{\mu\nu}R^{\mu\nu}, R_{\mu\nu\rho\sigma}R^{\mu\nu\rho\sigma})$ gravity, a general class of fourth-order theories of gravity. By applying this method, the metric, presented in the form of the multipole expansion, outside a spatially compact source up to $1/c^3$ order is provided, and the closed-form expressions for the source multipole moments are all presented explicitly. The metric consists of the massless tensor part, the massive scalar part, and the massive tensor part, where the former is exactly the metric in General Relativity, and the latter two are the corrections to it. It is shown that the corrections bear the Yukawa-like dependence on the two massive parameters and predict the appearance of six additional sets of source multipole moments, which indicates that up to $1/c^3$ order, there exist six degrees of freedom beyond General Relativity within $F(R,R_{\mu\nu}R^{\mu\nu}, R_{\mu\nu\rho\sigma}R^{\mu\nu\rho\sigma})$ gravity. By means of the metric, for a gyroscope moving around the source without experiencing any torque, the multipole expansions of its spin's angular velocities of the Thomas precession, the geodetic precession, and the Lense-Thirring precession are derived, and from them, the corrections to the angular velocities of the three types of precession in General Relativity can be read off. These results indicate that differently from $f(R)$ or $f(R,\mathcal{G})$ gravity, the most salient feature of the general $F(R,R_{\mu\nu}R^{\mu\nu}, R_{\mu\nu\rho\sigma}R^{\mu\nu\rho\sigma})$ gravity is that it gives the nonvanishing correction to the gyroscopic spin's angular velocity of the Lense-Thirring precession in General Relativity.
|
2311.14800
|
Carlos A. R. Herdeiro
|
C. A. R. Herdeiro, E. Radu, N. Sanchis-Gual, N. M. Santos, E. dos
Santos Costa Filho
|
The non-spherical ground state of Proca stars
|
6 pages, 4 figures; ; movies of the numerical simulations reported
can be found in http://gravitation.web.ua.pt/index.php/node/4657
|
Phys. Lett. B 852 (2024) 138595
|
10.1016/j.physletb.2024.138595
| null |
gr-qc hep-th math-ph math.MP
|
http://creativecommons.org/licenses/by/4.0/
|
Spherical Proca Stars (PSs) are regarded as the ground state amongst the
family of PSs. In accordance, spherical PSs are thought to have a fundamental
branch of stable solutions. In this Letter, we provide energetic, morphological
and dynamical evidence that spherical PSs are actually excited states. The
ground state is shown to be a family of static, non-spherical, in fact prolate,
PSs. The spherical stars in the fundamental branch, albeit stable against
spherical perturbations, turn out to succumb to non-spherical dynamics,
undergoing an isometry breaking into prolate PSs. We also provide evidence for
the dynamical formation of prolate PSs, starting from spherical dilute initial
data, via gravitational cooling. Consequently, PSs provide a remarkable example
of (possibly compact) relativistic stars, in General Relativity minimally
coupled to a simple, physical, field theory model, where staticity plus
stability implies non-sphericity.
|
[
{
"created": "Fri, 24 Nov 2023 19:00:02 GMT",
"version": "v1"
}
] |
2024-03-29
|
[
[
"Herdeiro",
"C. A. R.",
""
],
[
"Radu",
"E.",
""
],
[
"Sanchis-Gual",
"N.",
""
],
[
"Santos",
"N. M.",
""
],
[
"Filho",
"E. dos Santos Costa",
""
]
] |
Spherical Proca Stars (PSs) are regarded as the ground state amongst the family of PSs. In accordance, spherical PSs are thought to have a fundamental branch of stable solutions. In this Letter, we provide energetic, morphological and dynamical evidence that spherical PSs are actually excited states. The ground state is shown to be a family of static, non-spherical, in fact prolate, PSs. The spherical stars in the fundamental branch, albeit stable against spherical perturbations, turn out to succumb to non-spherical dynamics, undergoing an isometry breaking into prolate PSs. We also provide evidence for the dynamical formation of prolate PSs, starting from spherical dilute initial data, via gravitational cooling. Consequently, PSs provide a remarkable example of (possibly compact) relativistic stars, in General Relativity minimally coupled to a simple, physical, field theory model, where staticity plus stability implies non-sphericity.
|
1503.04621
|
Ioannis Contopoulos
|
Demetrios B. Papadopoulos, Ioannis Contopoulos, Kostas D. Kokkotas and
Nikolaos Stergioulas
|
Radiation from charged particles on eccentric orbits in a dipolar
magnetic field around a Schwarzschild black hole
|
13 pages, Journal of Mathematical Physics
| null |
10.1007/s10714-015-1889-1
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We obtain an approximate solution for the motion of a charged particle around
a Schwarzschild black hole immersed in a weak dipolar magnetic field. We focus
on eccentric bound orbits in the equatorial plane of the Schwarzschild black
hole and derive an analytic expression for the spectral distribution of the
electromagnetic emission from a charged particle on such an orbit. Two sets of
harmonic contributions appear, with specific frequency spacing. The expression
can be written in compact form, if it is truncated up to the lowest order
harmonic contributions.
|
[
{
"created": "Mon, 16 Mar 2015 12:28:08 GMT",
"version": "v1"
}
] |
2015-06-24
|
[
[
"Papadopoulos",
"Demetrios B.",
""
],
[
"Contopoulos",
"Ioannis",
""
],
[
"Kokkotas",
"Kostas D.",
""
],
[
"Stergioulas",
"Nikolaos",
""
]
] |
We obtain an approximate solution for the motion of a charged particle around a Schwarzschild black hole immersed in a weak dipolar magnetic field. We focus on eccentric bound orbits in the equatorial plane of the Schwarzschild black hole and derive an analytic expression for the spectral distribution of the electromagnetic emission from a charged particle on such an orbit. Two sets of harmonic contributions appear, with specific frequency spacing. The expression can be written in compact form, if it is truncated up to the lowest order harmonic contributions.
|
gr-qc/0207106
|
Joshua L. Willis
|
Abhay Ashtekar, Stephen Fairhurst, and Joshua L. Willis
|
Quantum gravity, shadow states, and quantum mechanics
|
35 pages, no figures, RevTeX4 with AMSTeX; v2: three references
added. v3: Sections IV and V revised in view of discussions at the recent
Schr\"odinger Institute workshop on quantum field theory in curved
space-times. In particular, now this simple quantum mechanical example also
serves as a (partial) introduction to the constructions and techniques used
in quantum geometry
|
Class.Quant.Grav. 20 (2003) 1031-1062
|
10.1088/0264-9381/20/6/302
|
CGPG-02/7-2
|
gr-qc hep-th quant-ph
| null |
A program was recently initiated to bridge the gap between the Planck scale
physics described by loop quantum gravity and the familiar low energy world. We
illustrate the conceptual problems and their solutions through a toy model:
quantum mechanics of a point particle. Maxwell fields will be discussed in the
second paper of this series which further develops the program and provides
details.
|
[
{
"created": "Fri, 26 Jul 2002 17:08:42 GMT",
"version": "v1"
},
{
"created": "Tue, 30 Jul 2002 17:16:21 GMT",
"version": "v2"
},
{
"created": "Wed, 20 Nov 2002 23:44:54 GMT",
"version": "v3"
}
] |
2017-08-23
|
[
[
"Ashtekar",
"Abhay",
""
],
[
"Fairhurst",
"Stephen",
""
],
[
"Willis",
"Joshua L.",
""
]
] |
A program was recently initiated to bridge the gap between the Planck scale physics described by loop quantum gravity and the familiar low energy world. We illustrate the conceptual problems and their solutions through a toy model: quantum mechanics of a point particle. Maxwell fields will be discussed in the second paper of this series which further develops the program and provides details.
|
gr-qc/0012070
|
B. S. Sathyaprakash
|
T. Damour, B.R. Iyer and B.S. Sathyaprakash
|
Detecting Binary Black Holes With Efficient and Reliable Templates
|
9 pages, 3 figures
| null | null | null |
gr-qc
| null |
Detecting binary black holes in interferometer data requires an accurate
knowledge of the orbital phase evolution of the system. From the point of view
of data analysis one also needs fast algorithms to compute the templates that
will employed in searching for black hole binaries. Recently, there has been
progress on both these fronts: On the one hand, re-summation techniques have
made it possible to accelerate the convergence of poorly convergent asymptotic
post-Newtonian series and derive waveforms beyond the conventional adiabatic
approximation. We now have a waveform model that extends beyond the inspiral
regime into the plunge phase followed by the quasi-normal mode ringing. On the
other hand, explicit Fourier domain waveforms have been derived that make the
generation of waveforms fast enough so as not to be a burden on the
computational resources required in filtering the detector data. These new
developments should make it possible to efficiently and reliably search for
black hole binaries in data from first interferometers.
|
[
{
"created": "Tue, 19 Dec 2000 15:34:27 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Damour",
"T.",
""
],
[
"Iyer",
"B. R.",
""
],
[
"Sathyaprakash",
"B. S.",
""
]
] |
Detecting binary black holes in interferometer data requires an accurate knowledge of the orbital phase evolution of the system. From the point of view of data analysis one also needs fast algorithms to compute the templates that will employed in searching for black hole binaries. Recently, there has been progress on both these fronts: On the one hand, re-summation techniques have made it possible to accelerate the convergence of poorly convergent asymptotic post-Newtonian series and derive waveforms beyond the conventional adiabatic approximation. We now have a waveform model that extends beyond the inspiral regime into the plunge phase followed by the quasi-normal mode ringing. On the other hand, explicit Fourier domain waveforms have been derived that make the generation of waveforms fast enough so as not to be a burden on the computational resources required in filtering the detector data. These new developments should make it possible to efficiently and reliably search for black hole binaries in data from first interferometers.
|
1003.4892
|
Sergey Pavluchenko
|
S.A. Pavluchenko
|
The dynamics of the flat anisotropic models in the Lovelock gravity. I:
The even-dimensional case
|
20 pages, 7 figures; v2 - minor corrections, references added
|
Phys.Rev.D82:104021,2010
|
10.1103/PhysRevD.82.104021
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this article we give a full description of the dynamics of the flat
anisotropic (4+1)-dimensional cosmological model in the presence of both
Gauss-Bonnet and Einstein contributions. This is the first complete description
of this model with both terms taken into account. Our data is obtained using
the numerical analysis, though, we use analytics to explain some features of
the results obtained, and the same analytics could be applied to
higher-dimensional models in higher-order Lovelock corrections. Firstly, we
investigate the vacuum model and give a description of all regimes; then, we
add a matter source in the form of perfect fluid and study the influence the
matter exerts upon the dynamics. Thus, we give a description of matter regimes
as well. Additionally, we demonstrate that the presence of matter not only
"improves" the situation with a smooth transition between the standard
singularity and the Kasner regime, but also brings additional regimes and even
partially "erases" the boundaries between different regimes inside the same
triplet. Finally, we discuss the numerical and analytical results obtained and
their generalization to the higher-order models.
|
[
{
"created": "Thu, 25 Mar 2010 13:58:59 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Apr 2010 11:55:22 GMT",
"version": "v2"
}
] |
2010-12-13
|
[
[
"Pavluchenko",
"S. A.",
""
]
] |
In this article we give a full description of the dynamics of the flat anisotropic (4+1)-dimensional cosmological model in the presence of both Gauss-Bonnet and Einstein contributions. This is the first complete description of this model with both terms taken into account. Our data is obtained using the numerical analysis, though, we use analytics to explain some features of the results obtained, and the same analytics could be applied to higher-dimensional models in higher-order Lovelock corrections. Firstly, we investigate the vacuum model and give a description of all regimes; then, we add a matter source in the form of perfect fluid and study the influence the matter exerts upon the dynamics. Thus, we give a description of matter regimes as well. Additionally, we demonstrate that the presence of matter not only "improves" the situation with a smooth transition between the standard singularity and the Kasner regime, but also brings additional regimes and even partially "erases" the boundaries between different regimes inside the same triplet. Finally, we discuss the numerical and analytical results obtained and their generalization to the higher-order models.
|
2208.13636
|
Pardyumn Kumar Sahoo
|
Sanjay Mandal, P.K. Sahoo, J.R.L. Santos
|
Reply to "Comment on `Energy Conditions in $f(Q)$ gravity'"
|
Published version in PRD
|
Phys. Rev. D 106 (2022) 048502
|
10.1103/PhysRevD.106.048502
| null |
gr-qc hep-th
|
http://creativecommons.org/licenses/by/4.0/
|
Recently, Avik De and L.T. How claim that we have not followed an effective
theory approach for $f(Q)$ gravity, missing relevant terms to compute the
energy conditions [Phys. Rev. D 102, 024057 (2020)]. They also state that we
did not present how the pressure and energy density follow a set of energy
condition criteria. In this reply we show how the effective density and
effective pressure found in the comment yield to the same Fridmann Equations
presented in our article. Therefore, we claim that the comment only introduces
an equivalent path to derive the Friedmann Equations and that the extra terms
found by Avik De and L.T. How are consequence of their specific definition for
their effective density and effective pressure. However, such terms do not
change the equations for $\rho$ and $p$. Consequently, these extra terms are
not going to change the energy constraints presented by us in Phys. Rev. D 102,
024057 (2020).
|
[
{
"created": "Mon, 29 Aug 2022 14:37:18 GMT",
"version": "v1"
}
] |
2022-08-30
|
[
[
"Mandal",
"Sanjay",
""
],
[
"Sahoo",
"P. K.",
""
],
[
"Santos",
"J. R. L.",
""
]
] |
Recently, Avik De and L.T. How claim that we have not followed an effective theory approach for $f(Q)$ gravity, missing relevant terms to compute the energy conditions [Phys. Rev. D 102, 024057 (2020)]. They also state that we did not present how the pressure and energy density follow a set of energy condition criteria. In this reply we show how the effective density and effective pressure found in the comment yield to the same Fridmann Equations presented in our article. Therefore, we claim that the comment only introduces an equivalent path to derive the Friedmann Equations and that the extra terms found by Avik De and L.T. How are consequence of their specific definition for their effective density and effective pressure. However, such terms do not change the equations for $\rho$ and $p$. Consequently, these extra terms are not going to change the energy constraints presented by us in Phys. Rev. D 102, 024057 (2020).
|
2010.07561
|
Masato Nozawa
|
Masato Nozawa
|
Static spacetimes haunted by a phantom scalar field III: asymptotically
(A)dS solutions
|
4 figures, 1 table, 37 pages; v2 to appear in PRD
|
Phys. Rev. D 103, 024005 (2021)
|
10.1103/PhysRevD.103.024005
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The static and spherically symmetric solutions in $n(\ge 4)$-dimensional
Einstein-phantom-scalar system fall into three family: (i) the Fisher solution,
(ii) the Ellis-Gibbons solution, and (iii) the Ellis-Bronnikov solution. We
exploit these solutions as seed to generate a bunch of corresponding
asymptotically (A)dS spacetimes, at the price of introducing the potential of
the scalar field. Despite that the potentials are different for each solution,
each potential is expressed in terms of the superpotential as in supergravity.
We discuss the global structure of these solutions in detail and spell out the
domain of parameters under which each solution represents a black
hole/wormhole. The Ellis-Bronnikov class of solutions presents novel examples
of spherical traversable wormholes that interpolate two different (A)dS
critical points of the (super)potential.
|
[
{
"created": "Thu, 15 Oct 2020 07:21:28 GMT",
"version": "v1"
},
{
"created": "Tue, 5 Jan 2021 03:14:55 GMT",
"version": "v2"
}
] |
2021-01-13
|
[
[
"Nozawa",
"Masato",
""
]
] |
The static and spherically symmetric solutions in $n(\ge 4)$-dimensional Einstein-phantom-scalar system fall into three family: (i) the Fisher solution, (ii) the Ellis-Gibbons solution, and (iii) the Ellis-Bronnikov solution. We exploit these solutions as seed to generate a bunch of corresponding asymptotically (A)dS spacetimes, at the price of introducing the potential of the scalar field. Despite that the potentials are different for each solution, each potential is expressed in terms of the superpotential as in supergravity. We discuss the global structure of these solutions in detail and spell out the domain of parameters under which each solution represents a black hole/wormhole. The Ellis-Bronnikov class of solutions presents novel examples of spherical traversable wormholes that interpolate two different (A)dS critical points of the (super)potential.
|
1710.03209
|
James Dilts
|
James Dilts, Michael Holst
|
When Do Spacetimes Have Constant Mean Curvature Slices?
|
11 pages
| null | null | null |
gr-qc math.DG
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Many results in mathematical relativity, including results for both the
initial data problem and for the evolution problem, rely on the existence of a
constant mean curvature (CMC) Cauchy surface in the underlying spacetime.
However, it is known that some spacetimes have no CMC Cauchy surfaces (slices).
This is an obstacle for many results and constructions with these types of
spacetimes, and is particularly worrisome since it is not known whether
spacetimes that do have CMC slices are in any sense generic. In this expository
paper, we will discuss the known results about the existence (and
non-existence) of CMC slices, examine the evidence for cases which are unknown,
and make several conjectures concerning the existence of CMC slices and their
generality.
|
[
{
"created": "Mon, 9 Oct 2017 17:40:26 GMT",
"version": "v1"
}
] |
2017-10-10
|
[
[
"Dilts",
"James",
""
],
[
"Holst",
"Michael",
""
]
] |
Many results in mathematical relativity, including results for both the initial data problem and for the evolution problem, rely on the existence of a constant mean curvature (CMC) Cauchy surface in the underlying spacetime. However, it is known that some spacetimes have no CMC Cauchy surfaces (slices). This is an obstacle for many results and constructions with these types of spacetimes, and is particularly worrisome since it is not known whether spacetimes that do have CMC slices are in any sense generic. In this expository paper, we will discuss the known results about the existence (and non-existence) of CMC slices, examine the evidence for cases which are unknown, and make several conjectures concerning the existence of CMC slices and their generality.
|
2010.05845
|
Fabrizio Di Giovanni
|
Fabrizio Di Giovanni, Nicolas Sanchis-Gual, Pablo Cerd\'a-Dur\'an,
Miguel Zilh\~ao, Carlos Herdeiro, Jos\'e A. Font, Eugen Radu
|
On the dynamical bar-mode instability in spinning bosonic stars
|
16 pages, 11 figures. A longer version of the abstract in the pdf
| null |
10.1103/PhysRevD.102.124009
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Spinning bosonic stars (SBSs) can form from the gravitational collapse of a
dilute cloud of scalar/Proca particles with non-zero angular momentum. In a
recent work we found that the scalar stars are transient due to a
non-axisymmetric instability which triggers the loss of angular momentum. We
further study the dynamical formation of SBSs using 3-dimensional
numerical-relativity simulations of the Einstein-(massive, complex)Klein-Gordon
system and of the Einstein-(complex)Proca system. We incorporate a quartic
self-interaction potential in the scalar case to gauge its effect on the
instability; we investigate (m=2) Proca stars to assess their stability; we
attempt to relate the instability of SBSs to the growth rate of azimuthal
density modes and the existence of a corotation point. We show that: the
self-interaction potential can only delay the instability in scalar SBSs; m=2
Proca stars always migrate to the stable m=1 spheroidal family; unstable m=2
Proca stars and m=1 scalar boson stars exhibit a corotation point. This
establishes a parallelism with rotating neutron stars affected by dynamical
bar-mode instabilities. We compute the gravitational waves (GWs) emitted and
investigate the detectability of the waveforms comparing the characteristic
strain of the signal with the sensitivity curves of a variety of detectors,
computing the signal-to-noise ratio. By assuming that the characteristic
damping timescale of the bar-like deformation in SBSs is only set by GWs
emission and not by viscosity (unlike in neutron stars), we find that the
post-collapse emission could be orders of magnitude more energetic than that of
the bar-mode instability itself. Our results indicate that GW observations of
SBSs might be within the reach of future experiments, offering a potential
means to establish the existence of such stars and to place tight constraints
on the mass of the bosonic particle.
|
[
{
"created": "Mon, 12 Oct 2020 16:51:28 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Oct 2020 12:56:14 GMT",
"version": "v2"
}
] |
2020-12-09
|
[
[
"Di Giovanni",
"Fabrizio",
""
],
[
"Sanchis-Gual",
"Nicolas",
""
],
[
"Cerdá-Durán",
"Pablo",
""
],
[
"Zilhão",
"Miguel",
""
],
[
"Herdeiro",
"Carlos",
""
],
[
"Font",
"José A.",
""
],
[
"Radu",
"Eugen",
""
]
] |
Spinning bosonic stars (SBSs) can form from the gravitational collapse of a dilute cloud of scalar/Proca particles with non-zero angular momentum. In a recent work we found that the scalar stars are transient due to a non-axisymmetric instability which triggers the loss of angular momentum. We further study the dynamical formation of SBSs using 3-dimensional numerical-relativity simulations of the Einstein-(massive, complex)Klein-Gordon system and of the Einstein-(complex)Proca system. We incorporate a quartic self-interaction potential in the scalar case to gauge its effect on the instability; we investigate (m=2) Proca stars to assess their stability; we attempt to relate the instability of SBSs to the growth rate of azimuthal density modes and the existence of a corotation point. We show that: the self-interaction potential can only delay the instability in scalar SBSs; m=2 Proca stars always migrate to the stable m=1 spheroidal family; unstable m=2 Proca stars and m=1 scalar boson stars exhibit a corotation point. This establishes a parallelism with rotating neutron stars affected by dynamical bar-mode instabilities. We compute the gravitational waves (GWs) emitted and investigate the detectability of the waveforms comparing the characteristic strain of the signal with the sensitivity curves of a variety of detectors, computing the signal-to-noise ratio. By assuming that the characteristic damping timescale of the bar-like deformation in SBSs is only set by GWs emission and not by viscosity (unlike in neutron stars), we find that the post-collapse emission could be orders of magnitude more energetic than that of the bar-mode instability itself. Our results indicate that GW observations of SBSs might be within the reach of future experiments, offering a potential means to establish the existence of such stars and to place tight constraints on the mass of the bosonic particle.
|
1303.1185
|
Neil J. Cornish
|
Laura Sampson, Neil Cornish and Nicolas Yunes
|
Gravitational Wave Tests of Strong Field General Relativity with Binary
Inspirals: Realistic Injections and Optimal Model Selection
|
12 pages, 8 figures
| null |
10.1103/PhysRevD.87.102001
| null |
gr-qc astro-ph.HE
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study generic tests of strong-field General Relativity using gravitational
waves emitted during the inspiral of compact binaries. Previous studies have
considered simple extensions to the standard post-Newtonian waveforms that
differ by a single term in the phase. Here we improve on these studies by (i)
increasing the realism of injections and (ii) determining the optimal waveform
families for detecting and characterizing such signals. We construct waveforms
that deviate from those in General Relativity through a series of
post-Newtonian terms, and find that these higher-order terms can affect our
ability to test General Relativity, in some cases by making it easier to detect
a deviation, and in some cases by making it more difficult. We find that simple
single-phase post-Einsteinian waveforms are sufficient for detecting deviations
from General Relativity, and there is little to be gained from using more
complicated models with multiple phase terms. The results found here will help
guide future attempts to test General Relativity with advanced ground-based
detectors.
|
[
{
"created": "Tue, 5 Mar 2013 21:00:04 GMT",
"version": "v1"
}
] |
2013-05-22
|
[
[
"Sampson",
"Laura",
""
],
[
"Cornish",
"Neil",
""
],
[
"Yunes",
"Nicolas",
""
]
] |
We study generic tests of strong-field General Relativity using gravitational waves emitted during the inspiral of compact binaries. Previous studies have considered simple extensions to the standard post-Newtonian waveforms that differ by a single term in the phase. Here we improve on these studies by (i) increasing the realism of injections and (ii) determining the optimal waveform families for detecting and characterizing such signals. We construct waveforms that deviate from those in General Relativity through a series of post-Newtonian terms, and find that these higher-order terms can affect our ability to test General Relativity, in some cases by making it easier to detect a deviation, and in some cases by making it more difficult. We find that simple single-phase post-Einsteinian waveforms are sufficient for detecting deviations from General Relativity, and there is little to be gained from using more complicated models with multiple phase terms. The results found here will help guide future attempts to test General Relativity with advanced ground-based detectors.
|
1412.1291
|
Behnam Pourhassan
|
J. Sadeghi, H. Farahani, B. Pourhassan
|
Interacting Holographic Extended Chaplygin Gas and Phantom Cosmology in
the Light of BICEP2
|
15 pages, 3 figures, References added in version 2
|
Eur. Phys. J. Plus 130 (2015) 84
|
10.1140/epjp/i2015-15084-6
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, we study the holographic dark energy density and interacting
extended Chaplygin gas energy density in the Einstein gravity. We reconstruct
the scalar field and the scalar potential describing the extended Chaplygin
gas. In the special case, we obtain energy density and investigate some
cosmological parameters. Assuming interaction between components we find energy
density for some different parametrization of total EoS. We analyze tensor to
scalar ratio and use recent observational data of BICEP2 to fix the model
parameters.
|
[
{
"created": "Wed, 3 Dec 2014 12:07:47 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Dec 2014 19:32:45 GMT",
"version": "v2"
}
] |
2015-04-28
|
[
[
"Sadeghi",
"J.",
""
],
[
"Farahani",
"H.",
""
],
[
"Pourhassan",
"B.",
""
]
] |
In this paper, we study the holographic dark energy density and interacting extended Chaplygin gas energy density in the Einstein gravity. We reconstruct the scalar field and the scalar potential describing the extended Chaplygin gas. In the special case, we obtain energy density and investigate some cosmological parameters. Assuming interaction between components we find energy density for some different parametrization of total EoS. We analyze tensor to scalar ratio and use recent observational data of BICEP2 to fix the model parameters.
|
1804.11203
|
Luigi Tedesco
|
Luigi Tedesco
|
Ellipsoidal Expansion of the Universe, Cosmic Shear, Acceleration and
Jerk Parameter
|
13 pages, accepted for publication in European Physical Journal Plus
| null | null | null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In order to study if the anisotropy of the spacetime may induce differences
in the cosmic shear or in deceleration parameter we investigate in Bianchi I
Universe the most general expression for the cosmic shear and we study the
connections between deceleration parameter and cosmic shear. We also consider a
shear parametric approach to measure the transition from decelerating to an
accelerating Universe. We also study the connection between jerk parameter and
ellipsoidal Universe.
|
[
{
"created": "Thu, 26 Apr 2018 16:08:44 GMT",
"version": "v1"
}
] |
2018-05-03
|
[
[
"Tedesco",
"Luigi",
""
]
] |
In order to study if the anisotropy of the spacetime may induce differences in the cosmic shear or in deceleration parameter we investigate in Bianchi I Universe the most general expression for the cosmic shear and we study the connections between deceleration parameter and cosmic shear. We also consider a shear parametric approach to measure the transition from decelerating to an accelerating Universe. We also study the connection between jerk parameter and ellipsoidal Universe.
|
gr-qc/0508017
|
Nese Ozdemir
|
N. Ozdemir
|
Spinning cosmic strings: a general class of solutions
| null |
Int.J.Mod.Phys. A20 (2005) 2821-2832
|
10.1142/S0217751X05020781
| null |
gr-qc
| null |
In this work, we give a general class of solutions of the spinning cosmic
string in Einstein's theory of gravity. After treating same problem in Einstein
Cartan (EC) theory of gravity, the exact solution satisfying both exterior and
interior space-times representing a spin fluid moving along the symmetry axis
is presented in the EC theory. The existence of closed timelike curves in this
spacetime are also examined.
|
[
{
"created": "Thu, 4 Aug 2005 14:20:08 GMT",
"version": "v1"
}
] |
2009-11-11
|
[
[
"Ozdemir",
"N.",
""
]
] |
In this work, we give a general class of solutions of the spinning cosmic string in Einstein's theory of gravity. After treating same problem in Einstein Cartan (EC) theory of gravity, the exact solution satisfying both exterior and interior space-times representing a spin fluid moving along the symmetry axis is presented in the EC theory. The existence of closed timelike curves in this spacetime are also examined.
|
2403.02230
|
Peter Horvathy
|
Q.L. Zhao, P. M. Zhang, P.A. Horvathy
|
Conformally related vacuum gravitational waves, and their symmetries
|
Reorganized, with some new results. 36 pages, 18 figures
| null | null | null |
gr-qc hep-th math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A special conformal transformation which carries a vacuum gravitational wave
into another vacuum one is built by using M\"obius-redefined time. It can
either transform a globally defined vacuum wave into a vacuum sandwich wave, or
carry the gravitational wave into itself. The first type, illustrated by
linearly and circularly polarized vacuum plane gravitational waves, permutes
the symmetries and the geodesics. Our pp waves with conformal O(2,1) symmetry
of the second type, which seem to ahve escaped attention so far, are
anisotropic generalizations of the familiar inverse-square profile. An example
inspired by molecular physics, for which the particle can escape, or perform
periodic motion, or fall into the singularity is studied in detail.
|
[
{
"created": "Mon, 4 Mar 2024 17:20:55 GMT",
"version": "v1"
},
{
"created": "Tue, 12 Mar 2024 09:00:21 GMT",
"version": "v2"
}
] |
2024-03-13
|
[
[
"Zhao",
"Q. L.",
""
],
[
"Zhang",
"P. M.",
""
],
[
"Horvathy",
"P. A.",
""
]
] |
A special conformal transformation which carries a vacuum gravitational wave into another vacuum one is built by using M\"obius-redefined time. It can either transform a globally defined vacuum wave into a vacuum sandwich wave, or carry the gravitational wave into itself. The first type, illustrated by linearly and circularly polarized vacuum plane gravitational waves, permutes the symmetries and the geodesics. Our pp waves with conformal O(2,1) symmetry of the second type, which seem to ahve escaped attention so far, are anisotropic generalizations of the familiar inverse-square profile. An example inspired by molecular physics, for which the particle can escape, or perform periodic motion, or fall into the singularity is studied in detail.
|
gr-qc/0501027
|
Jorge Pullin
|
Rodolfo Gambini, Rafael Porto, Jorge Pullin
|
Fundamental decoherence in quantum gravity
|
6 pages, to appear in the proceedings of DICE 2004 (Piombino, Italy)
|
Braz.J.Phys. 35 (2005) 266-270
| null |
LSU-REL-010905
|
gr-qc
| null |
A recently introduced discrete formalism allows to solve the problem of time
in quantum gravity in a relational manner. Quantum mechanics formulated with a
relational time is not exactly unitary and implies a fundamental mechanism for
decoherence of quantum states. The mechanism is strong enough to render the
black hole information puzzle unobservable.
|
[
{
"created": "Sun, 9 Jan 2005 23:04:30 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Gambini",
"Rodolfo",
""
],
[
"Porto",
"Rafael",
""
],
[
"Pullin",
"Jorge",
""
]
] |
A recently introduced discrete formalism allows to solve the problem of time in quantum gravity in a relational manner. Quantum mechanics formulated with a relational time is not exactly unitary and implies a fundamental mechanism for decoherence of quantum states. The mechanism is strong enough to render the black hole information puzzle unobservable.
|
1008.0991
|
Jo\~ao Paulo Pitelli Manoel
|
Patricio S. Letelier and Jo\~ao Paulo M. Pitelli
|
Quantum singularities in FRW universe revisited
|
15 pages, revtex, accepted for publication in PRD
|
Phys.Rev.D82:043514,2010
|
10.1103/PhysRevD.82.043514
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The components of the Riemann tensor in the tetrad basis are quantized and,
through the Einstein equation, we find the local expectation value in the
ontological interpretation of quantum mechanics of the energy density and
pressure of a perfect fluid with equation of state $p=\frac{1}{3}\rho$ in the
flat Friedmann-Robertson-Walker quantum cosmological model. The quantum
behavior of the equation of state and energy conditions are then studied and it
is shown that the later is violated since the singularity is removed with the
introduction of quantum cosmology, but in the classical limit both the equation
of state and the energy conditions behave as in the classical model. We also
calculate the expectation value of the scale factor for several wave packets in
the many-worlds interpretation in order to show the independence of the non
singular character of the quantum cosmological model with respect to the wave
packet representing the wave function of the Universe. It is also shown that,
with the introduction of non-normalizable wave packets, solutions of the
Wheeler-DeWitt equation, the singular character of the scale factor, can be
recovered in the ontological interpretation.
|
[
{
"created": "Thu, 5 Aug 2010 15:00:14 GMT",
"version": "v1"
}
] |
2010-09-02
|
[
[
"Letelier",
"Patricio S.",
""
],
[
"Pitelli",
"João Paulo M.",
""
]
] |
The components of the Riemann tensor in the tetrad basis are quantized and, through the Einstein equation, we find the local expectation value in the ontological interpretation of quantum mechanics of the energy density and pressure of a perfect fluid with equation of state $p=\frac{1}{3}\rho$ in the flat Friedmann-Robertson-Walker quantum cosmological model. The quantum behavior of the equation of state and energy conditions are then studied and it is shown that the later is violated since the singularity is removed with the introduction of quantum cosmology, but in the classical limit both the equation of state and the energy conditions behave as in the classical model. We also calculate the expectation value of the scale factor for several wave packets in the many-worlds interpretation in order to show the independence of the non singular character of the quantum cosmological model with respect to the wave packet representing the wave function of the Universe. It is also shown that, with the introduction of non-normalizable wave packets, solutions of the Wheeler-DeWitt equation, the singular character of the scale factor, can be recovered in the ontological interpretation.
|
1009.3633
|
Anastasia Golubtsova
|
Anastasia Golubtsova
|
On multidimensional cosmological solutions with scalar fields and
2-forms corresponding to rank-3 Lie algebras: acceleration and small
variation of G
|
14 pages, 6 figures
|
Grav.Cosmol.16:298-306,2010
|
10.1134/S0202289310040079
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
By means of a simple model we investigate the possibility of an accelerated
expansion of a 3-dimensional subspace in the presence of the variation of the
effective 4-dimensional constant obeying the experimental constraint.
Multidimensional cosmological solutions with m 2-form fields and l scalar
fields are presented. Solutions corresponding to rank-3 Lie algebras are
singled out and discussed. Each of solutions contain two factor spaces:
one-dimensional space M_1 and Ricci-flat space M_2. A 3-dimensional subspace of
M_2 is interpreted as "our" space. We show that there exists a time interval
where accelerated expansion of our 3D space is compatible with a small enough
variation of the effective gravitational constant G(\tau). This interval
contains \tau_0 which is the point of minimum of G(\tau) (here \tau is the
synchronous time variable). Special solutions with three phantom scalar fields
are analyzed. It is shown that in the vicinity of the point \tau_0 the time
variation of G(\tau) decreases in the sequence of Lie algebras A_3, C_3 and B_3
when the solutions with asymptotically power-law behavior of scale-factors for
\tau \to \infty are considered. Exact solutions with asymptotically exponential
accelerated expansion of 3D space are also considered.
|
[
{
"created": "Sun, 19 Sep 2010 12:27:47 GMT",
"version": "v1"
}
] |
2010-12-15
|
[
[
"Golubtsova",
"Anastasia",
""
]
] |
By means of a simple model we investigate the possibility of an accelerated expansion of a 3-dimensional subspace in the presence of the variation of the effective 4-dimensional constant obeying the experimental constraint. Multidimensional cosmological solutions with m 2-form fields and l scalar fields are presented. Solutions corresponding to rank-3 Lie algebras are singled out and discussed. Each of solutions contain two factor spaces: one-dimensional space M_1 and Ricci-flat space M_2. A 3-dimensional subspace of M_2 is interpreted as "our" space. We show that there exists a time interval where accelerated expansion of our 3D space is compatible with a small enough variation of the effective gravitational constant G(\tau). This interval contains \tau_0 which is the point of minimum of G(\tau) (here \tau is the synchronous time variable). Special solutions with three phantom scalar fields are analyzed. It is shown that in the vicinity of the point \tau_0 the time variation of G(\tau) decreases in the sequence of Lie algebras A_3, C_3 and B_3 when the solutions with asymptotically power-law behavior of scale-factors for \tau \to \infty are considered. Exact solutions with asymptotically exponential accelerated expansion of 3D space are also considered.
|
1108.2410
|
Salvatore Vitale
|
Salvatore Vitale and Michele Zanolin
|
Application of asymptotic expansions for maximum likelihood estimators'
errors to gravitational waves from binary mergers: the network case
|
26 pages, 10 figures
|
Phys. Rev. D 84 104020 (2011)
|
10.1103/PhysRevD.84.104020
| null |
gr-qc astro-ph.IM
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
This paper describes the most accurate analytical frequentist assessment to
date of the uncertainties in the estimation of physical parameters from
gravitational waves generated by non spinning binary systems and Earth-based
networks of laser interferometers. The paper quantifies how the accuracy in
estimating the intrinsic parameters mostly depends on the network signal to
noise ratio (SNR), but the resolution in the direction of arrival also strongly
depends on the network geometry.
We compare results for 6 different existing and possible global networks and
two different choices of the parameter space. We show how the fraction of the
sky where the one sigma angular resolution is below 2 square degrees increases
about 3 times when transitioning from the Hanford (USA), Livingston (USA) and
Cascina (Italy) network to possible 5 sites ones (while keeping the network SNR
fixed).
The technique adopted here is an asymptotic expansion of the uncertainties in
inverse powers of the signal to noise ratio where the first order is the
inverse Fisher information matrix. We show that a common approach to use
simplified parameter spaces and only the Fisher information matrix can largely
underestimate the uncertainties (by a factor ~7 for the one sigma sky
uncertainty in square degrees at a network SNR of ~15).
|
[
{
"created": "Thu, 11 Aug 2011 14:16:00 GMT",
"version": "v1"
},
{
"created": "Fri, 12 Aug 2011 15:52:25 GMT",
"version": "v2"
},
{
"created": "Tue, 11 Oct 2011 19:27:18 GMT",
"version": "v3"
}
] |
2013-05-29
|
[
[
"Vitale",
"Salvatore",
""
],
[
"Zanolin",
"Michele",
""
]
] |
This paper describes the most accurate analytical frequentist assessment to date of the uncertainties in the estimation of physical parameters from gravitational waves generated by non spinning binary systems and Earth-based networks of laser interferometers. The paper quantifies how the accuracy in estimating the intrinsic parameters mostly depends on the network signal to noise ratio (SNR), but the resolution in the direction of arrival also strongly depends on the network geometry. We compare results for 6 different existing and possible global networks and two different choices of the parameter space. We show how the fraction of the sky where the one sigma angular resolution is below 2 square degrees increases about 3 times when transitioning from the Hanford (USA), Livingston (USA) and Cascina (Italy) network to possible 5 sites ones (while keeping the network SNR fixed). The technique adopted here is an asymptotic expansion of the uncertainties in inverse powers of the signal to noise ratio where the first order is the inverse Fisher information matrix. We show that a common approach to use simplified parameter spaces and only the Fisher information matrix can largely underestimate the uncertainties (by a factor ~7 for the one sigma sky uncertainty in square degrees at a network SNR of ~15).
|
0708.3146
|
Sini R
|
Sini R., V. C. Kuriakose
|
Absorption cross section of RN black hole
|
6 pages, 2 figures
|
Int.J.Mod.Phys.D18:1-11,2009
|
10.1142/S0218271809014236
| null |
gr-qc
| null |
The behavior of a charged scalar field in the RN black hole space time is
studied using WKB approximation. In the present work it is assumed that matter
waves can get reflected from the event horizon. Using this effect, the Hawking
temperature and the absorption cross section for RN black hole placed in a
charged scalar field are calculated. The absorption cross section $\sigma
_{abs}$ is found to be inversely proportional to square of the Hawking
temperature of the black hole.
|
[
{
"created": "Thu, 23 Aug 2007 09:00:40 GMT",
"version": "v1"
}
] |
2009-03-24
|
[
[
"R.",
"Sini",
""
],
[
"Kuriakose",
"V. C.",
""
]
] |
The behavior of a charged scalar field in the RN black hole space time is studied using WKB approximation. In the present work it is assumed that matter waves can get reflected from the event horizon. Using this effect, the Hawking temperature and the absorption cross section for RN black hole placed in a charged scalar field are calculated. The absorption cross section $\sigma _{abs}$ is found to be inversely proportional to square of the Hawking temperature of the black hole.
|
0807.3537
|
Ezra Newman
|
Tim Adamo, Ezra T Newman
|
The Gravitational Field of a Radiating Electromagnetic Dipole
|
17
|
Class.Quant.Grav.25:245005,2008
|
10.1088/0264-9381/25/24/245005
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We begin with the time-dependent electric and magnetic dipole solution of
Maxwell's equations in Minkowski space. This Maxwell field is then used to
determine the behavior of the gravitational field (the Weyl tensor) as a
second-order perturbation off of the Minkowski background. From the Weyl tensor
we go on and find the spin-coefficients and the full metric in this
approximation. The physical meaning of many of the relations is discussed. In
particular we can identify the conservation law of angular momentum that
contains an angular momentum flux term.
|
[
{
"created": "Tue, 22 Jul 2008 18:51:27 GMT",
"version": "v1"
}
] |
2008-12-18
|
[
[
"Adamo",
"Tim",
""
],
[
"Newman",
"Ezra T",
""
]
] |
We begin with the time-dependent electric and magnetic dipole solution of Maxwell's equations in Minkowski space. This Maxwell field is then used to determine the behavior of the gravitational field (the Weyl tensor) as a second-order perturbation off of the Minkowski background. From the Weyl tensor we go on and find the spin-coefficients and the full metric in this approximation. The physical meaning of many of the relations is discussed. In particular we can identify the conservation law of angular momentum that contains an angular momentum flux term.
|
1105.2316
|
Norman G\"urlebeck
|
Norman G\"urlebeck
|
The interior solution of axially symmetric, stationary and rigidly
rotating dust configurations
|
minor corrections to the published version, 10 pages
|
Gen. Relativ. Gravit. (2009) 41:2687-2696
|
10.1007/s10714-009-0796-8
| null |
gr-qc astro-ph.GA
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
It is shown that the interior solution of axially symmetric, stationary and
rigidly rotating dust configurations is completely determined by the mass
density along the axis of rotation. The particularly interesting case of a mass
density, which is cylindrical symmetric in the interior of the dust
configuration, is presented. Among other things, this proves the non-existence
of homogeneous dust configurations.
|
[
{
"created": "Wed, 11 May 2011 20:39:33 GMT",
"version": "v1"
}
] |
2011-05-13
|
[
[
"Gürlebeck",
"Norman",
""
]
] |
It is shown that the interior solution of axially symmetric, stationary and rigidly rotating dust configurations is completely determined by the mass density along the axis of rotation. The particularly interesting case of a mass density, which is cylindrical symmetric in the interior of the dust configuration, is presented. Among other things, this proves the non-existence of homogeneous dust configurations.
|
1802.02281
|
Rafael Nunes
|
Rafael C. Nunes
|
Structure formation in $f(T)$ gravity and a solution for $H_0$ tension
|
18 pages, 8 figures, 1 table. Matches the version published in JCAP
|
JCAP 05(2018)052
|
10.1088/1475-7516/2018/05/052
| null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We investigate the evolution of scalar perturbations in $f(T)$ teleparallel
gravity and its effects on the cosmic microwave background (CMB) anisotropy.
The $f(T)$ gravity generalizes the teleparallel gravity which is formulated on
the Weitzenb\"ock spacetime, characterized by the vanishing curvature tensor
(absolute parallelism) and the non-vanishing torsion tensor. For the first
time, we derive the observational constraints on the modified teleparallel
gravity using the CMB temperature power spectrum from Planck's estimation, in
addition to data from baryonic acoustic oscillations (BAO) and local Hubble
constant measurements. We find that a small deviation of the $f(T)$ gravity
model from the $\Lambda$CDM cosmology is slightly favored. Besides that, the
$f(T)$ gravity model does not show tension on the Hubble constant that prevails
in the $\Lambda$CDM cosmology. It is clear that $f(T)$ gravity is also
consistent with the CMB observations, and undoubtedly it can serve as a viable
candidate amongst other modified gravity theories.
|
[
{
"created": "Wed, 7 Feb 2018 01:50:42 GMT",
"version": "v1"
},
{
"created": "Tue, 8 May 2018 16:18:21 GMT",
"version": "v2"
},
{
"created": "Sun, 20 May 2018 14:45:13 GMT",
"version": "v3"
}
] |
2018-05-22
|
[
[
"Nunes",
"Rafael C.",
""
]
] |
We investigate the evolution of scalar perturbations in $f(T)$ teleparallel gravity and its effects on the cosmic microwave background (CMB) anisotropy. The $f(T)$ gravity generalizes the teleparallel gravity which is formulated on the Weitzenb\"ock spacetime, characterized by the vanishing curvature tensor (absolute parallelism) and the non-vanishing torsion tensor. For the first time, we derive the observational constraints on the modified teleparallel gravity using the CMB temperature power spectrum from Planck's estimation, in addition to data from baryonic acoustic oscillations (BAO) and local Hubble constant measurements. We find that a small deviation of the $f(T)$ gravity model from the $\Lambda$CDM cosmology is slightly favored. Besides that, the $f(T)$ gravity model does not show tension on the Hubble constant that prevails in the $\Lambda$CDM cosmology. It is clear that $f(T)$ gravity is also consistent with the CMB observations, and undoubtedly it can serve as a viable candidate amongst other modified gravity theories.
|
2309.12932
|
Chen Wu
|
Zihan Xi, Chen Wu and Wenjun Guo
|
Different Regular Black Holes: Geodesic Structures of Test Particles
|
23 pages, 13 figures
| null | null | null |
gr-qc
|
http://creativecommons.org/licenses/by-sa/4.0/
|
This paper investigates the metric of previously proposed regular black
holes, calculates their effective potentials, and plots the curves of the
effective potentials. By determining the conserved quantities, the dynamical
equations for particles and photons near the black hole are derived. The
analysis encompasses timelike and null geodesics in different spacetimes,
including bound geodesics, unstable circular geodesics, stable circular
geodesics, and escape geodesics. The findings are presented through figures and
tables. Furthermore, the bound geodesics of the four regular black hole
spacetimes are analyzed, examining the average distance of particle orbits from
the center of the event horizon, the precession behavior of the perihelion, and
the probability of particles appearing inside the outer event horizon during
motion. Based on these analyses, a general formula is proposed, which yields
the existing metrics when specific parameter values are chosen. The impact of
parameter variations on the effective potential and geodesics is then computed
using this new formula.
|
[
{
"created": "Fri, 22 Sep 2023 15:30:57 GMT",
"version": "v1"
}
] |
2023-09-25
|
[
[
"Xi",
"Zihan",
""
],
[
"Wu",
"Chen",
""
],
[
"Guo",
"Wenjun",
""
]
] |
This paper investigates the metric of previously proposed regular black holes, calculates their effective potentials, and plots the curves of the effective potentials. By determining the conserved quantities, the dynamical equations for particles and photons near the black hole are derived. The analysis encompasses timelike and null geodesics in different spacetimes, including bound geodesics, unstable circular geodesics, stable circular geodesics, and escape geodesics. The findings are presented through figures and tables. Furthermore, the bound geodesics of the four regular black hole spacetimes are analyzed, examining the average distance of particle orbits from the center of the event horizon, the precession behavior of the perihelion, and the probability of particles appearing inside the outer event horizon during motion. Based on these analyses, a general formula is proposed, which yields the existing metrics when specific parameter values are chosen. The impact of parameter variations on the effective potential and geodesics is then computed using this new formula.
|
gr-qc/0404020
|
Holger Then
|
R. Aurich, F. Steiner and H. Then
|
Numerical computation of Maass waveforms and an application to cosmology
|
A version of the paper with high resolution figures is available at
http://www.physik.uni-ulm.de/theo/qc/publications.html
|
Hyperbolic Geometry and Applications in Quantum Chaos and
Cosmology; LMS 397, Cambridge University Press, 2011, pp. 229--269
|
10.1017/CBO9781139108782.008
| null |
gr-qc nlin.CD
| null |
We compute numerically eigenvalues and eigenfunctions of the Laplacian in a
three-dimensional hyperbolic space. Applying the results to cosmology, we
demonstrate that the methods learned in quantum chaos can be used in other
fields of research.
|
[
{
"created": "Tue, 6 Apr 2004 11:53:00 GMT",
"version": "v1"
}
] |
2017-04-27
|
[
[
"Aurich",
"R.",
""
],
[
"Steiner",
"F.",
""
],
[
"Then",
"H.",
""
]
] |
We compute numerically eigenvalues and eigenfunctions of the Laplacian in a three-dimensional hyperbolic space. Applying the results to cosmology, we demonstrate that the methods learned in quantum chaos can be used in other fields of research.
|
gr-qc/9412037
|
Warner A. Miller
|
Arkady Kheyfets and Warner A. Miller
|
Geometrodynamic Quantization and Time Evolution in Quantum Gravity
|
21 pages, 2 figures, revtex using epsf.sty, used uufiles -gz -9 macro
| null | null |
LA-UR-94-4148
|
gr-qc
| null |
We advance here a new gravity quantization procedure that explicitly utilizes
York's analysis of the geometrodynamic degrees of freedom. This geometrodynamic
procedure of quantization is based on a separation of the true dynamic
variables from the embedding parameters and a distinctly different treatment of
these two kinds of variables. While the dynamic variables are quantized
following the standard quantum mechanical and quantum field theoretic
procedures, the embedding parameters are determined by the "classical"
constraint equations in which the expectation values of the dynamic variables
are substituted in place of their classical values. This self-consistent
procedure of quantization leads to a linear Schrodinger equation augmented by
nonlinear "classical" constraints and supplies a natural description of time
evolution in quantum geometrodynamics. In particular, the procedure sheds new
light on the "problems of time" in quantum gravity.
|
[
{
"created": "Mon, 12 Dec 1994 20:25:05 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Kheyfets",
"Arkady",
""
],
[
"Miller",
"Warner A.",
""
]
] |
We advance here a new gravity quantization procedure that explicitly utilizes York's analysis of the geometrodynamic degrees of freedom. This geometrodynamic procedure of quantization is based on a separation of the true dynamic variables from the embedding parameters and a distinctly different treatment of these two kinds of variables. While the dynamic variables are quantized following the standard quantum mechanical and quantum field theoretic procedures, the embedding parameters are determined by the "classical" constraint equations in which the expectation values of the dynamic variables are substituted in place of their classical values. This self-consistent procedure of quantization leads to a linear Schrodinger equation augmented by nonlinear "classical" constraints and supplies a natural description of time evolution in quantum geometrodynamics. In particular, the procedure sheds new light on the "problems of time" in quantum gravity.
|
1911.11448
|
Piyabut Burikham
|
Taum Wuthicharn, Supakchai Ponglertsakul, Piyabut Burikham
|
Quasinormal Modes of Near-Extremal Black Holes and Black Strings in
Massive Gravity Background
|
34 pages, 3 figures, 14 tables, split from arXiv: 2010.05879[gr-qc]
as suggested by referee of EPJC
|
IJMPD(2021) 2150127
|
10.1142/S0218271821501273
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Two numerical methods are used to calculate quasinormal modes (QNMs) of
near-extremal black holes/strings in the generalized spherically/cylindrically
symmetric background, the Asymptotic Iteration Method (AIM) and the Spectral
Method. The numerical results confirm the accuracy of the approximate analytic
formula using the P\"{o}schl-Teller potential. Our analytic formula is used to
investigate the Strong Cosmic Censorship conjecture of extremal and
near-extremal black holes in Ref. \cite{Burikham:2020dfi}.
|
[
{
"created": "Tue, 26 Nov 2019 10:48:10 GMT",
"version": "v1"
},
{
"created": "Fri, 14 May 2021 08:12:58 GMT",
"version": "v2"
},
{
"created": "Mon, 17 May 2021 13:58:27 GMT",
"version": "v3"
},
{
"created": "Tue, 8 Feb 2022 14:03:23 GMT",
"version": "v4"
}
] |
2022-02-09
|
[
[
"Wuthicharn",
"Taum",
""
],
[
"Ponglertsakul",
"Supakchai",
""
],
[
"Burikham",
"Piyabut",
""
]
] |
Two numerical methods are used to calculate quasinormal modes (QNMs) of near-extremal black holes/strings in the generalized spherically/cylindrically symmetric background, the Asymptotic Iteration Method (AIM) and the Spectral Method. The numerical results confirm the accuracy of the approximate analytic formula using the P\"{o}schl-Teller potential. Our analytic formula is used to investigate the Strong Cosmic Censorship conjecture of extremal and near-extremal black holes in Ref. \cite{Burikham:2020dfi}.
|
2208.06408
|
Giovanni Maria Tomaselli
|
Lam Hui, Y.T. Albert Law, Luca Santoni, Guanhao Sun, Giovanni Maria
Tomaselli, Enrico Trincherini
|
Black hole superradiance with (dark) matter accretion
|
30+21 pages, 14 figures
| null |
10.1103/PhysRevD.107.104018
| null |
gr-qc astro-ph.HE hep-ph hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Studies of black hole superradiance often focus on the growth of a cloud in
isolation, accompanied by the spin-down of the black hole. In this paper, we
consider the additional effect of the accretion of matter and angular momentum
from the environment. We show that, in many cases, the black hole evolves by
drifting along the superradiance threshold, in which case the evolution of its
parameters can be described analytically or semi-analytically. We quantify the
conditions under which accretion can serve as a mechanism to increase the
cloud-to-black hole mass ratio, beyond the standard maximum of about 10%. This
occurs by a process we call over-superradiance, whereby accretion effectively
feeds the superradiance cloud, by way of the black hole. We give two explicit
examples: accretion from a vortex expected in wave dark matter and accretion
from a baryonic disk. In the former case, we estimate the accretion rate by
using an analytical fit to the asymptotic behavior of the confluent Heun
function. Level transition, whereby one cloud level grows while the other
shrinks, can be understood in a similar way.
|
[
{
"created": "Fri, 12 Aug 2022 17:59:58 GMT",
"version": "v1"
},
{
"created": "Fri, 27 Jan 2023 15:28:44 GMT",
"version": "v2"
},
{
"created": "Thu, 25 May 2023 15:21:56 GMT",
"version": "v3"
}
] |
2023-05-26
|
[
[
"Hui",
"Lam",
""
],
[
"Law",
"Y. T. Albert",
""
],
[
"Santoni",
"Luca",
""
],
[
"Sun",
"Guanhao",
""
],
[
"Tomaselli",
"Giovanni Maria",
""
],
[
"Trincherini",
"Enrico",
""
]
] |
Studies of black hole superradiance often focus on the growth of a cloud in isolation, accompanied by the spin-down of the black hole. In this paper, we consider the additional effect of the accretion of matter and angular momentum from the environment. We show that, in many cases, the black hole evolves by drifting along the superradiance threshold, in which case the evolution of its parameters can be described analytically or semi-analytically. We quantify the conditions under which accretion can serve as a mechanism to increase the cloud-to-black hole mass ratio, beyond the standard maximum of about 10%. This occurs by a process we call over-superradiance, whereby accretion effectively feeds the superradiance cloud, by way of the black hole. We give two explicit examples: accretion from a vortex expected in wave dark matter and accretion from a baryonic disk. In the former case, we estimate the accretion rate by using an analytical fit to the asymptotic behavior of the confluent Heun function. Level transition, whereby one cloud level grows while the other shrinks, can be understood in a similar way.
|
1604.03263
|
Piero Nicolini
|
Antonia M. Frassino, Sven K\"oppel and Piero Nicolini
|
Geometric model of black hole quantum $N$-portrait, extradimensions and
thermodynamics
|
36 pages, 8 figures, invited paper to the special issue "Entropy in
Quantum Gravity and Quantum Cosmology" edited by R. Garattini for the journal
"Entropy", accepted for publication; v2 version matching that published on
the journal
|
Entropy 2016, 18(5), 181
|
10.3390/e18050181
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Recently a short scale modified black hole metric, known as holographic
metric, has been proposed in order to capture the self-complete character of
gravity. In this paper we show that such a metric can reproduce some geometric
features expected from the quantum $N$-portrait beyond the semi-classical
limit. We show that for a generic $N$ this corresponds to having an effective
energy momentum tensor in Einstein equations or, equivalently, non-local terms
in the gravity action. We also consider the higher dimensional extension of the
metric and the case of an AdS cosmological term. We provide a detailed
thermodynamic analysis of both cases, with particular reference to the
repercussions on the Hawking-Page phase transition.
|
[
{
"created": "Tue, 12 Apr 2016 07:06:18 GMT",
"version": "v1"
},
{
"created": "Thu, 19 May 2016 21:34:50 GMT",
"version": "v2"
}
] |
2016-05-23
|
[
[
"Frassino",
"Antonia M.",
""
],
[
"Köppel",
"Sven",
""
],
[
"Nicolini",
"Piero",
""
]
] |
Recently a short scale modified black hole metric, known as holographic metric, has been proposed in order to capture the self-complete character of gravity. In this paper we show that such a metric can reproduce some geometric features expected from the quantum $N$-portrait beyond the semi-classical limit. We show that for a generic $N$ this corresponds to having an effective energy momentum tensor in Einstein equations or, equivalently, non-local terms in the gravity action. We also consider the higher dimensional extension of the metric and the case of an AdS cosmological term. We provide a detailed thermodynamic analysis of both cases, with particular reference to the repercussions on the Hawking-Page phase transition.
|
gr-qc/0306073
|
Kayll Lake
|
Kayll Lake
|
An explicit global covering of the Schwarzschild-Tangherlini black holes
|
3 pages revtex4, Updated references
|
JCAP 0310 (2003) 007
|
10.1088/1475-7516/2003/10/007
| null |
gr-qc hep-th
| null |
Explicit regular coordinates that cover all of the Tangherlini solutions
(Schwarzschild black holes of dimension $D>4$) are given. The coordinates
reduce to Israel coordinates for D=4.
|
[
{
"created": "Mon, 16 Jun 2003 18:51:01 GMT",
"version": "v1"
},
{
"created": "Wed, 18 Jun 2003 18:31:22 GMT",
"version": "v2"
}
] |
2009-11-10
|
[
[
"Lake",
"Kayll",
""
]
] |
Explicit regular coordinates that cover all of the Tangherlini solutions (Schwarzschild black holes of dimension $D>4$) are given. The coordinates reduce to Israel coordinates for D=4.
|
2209.02727
|
Marcello Miranda
|
Marcello Miranda, Daniele Vernieri, Salvatore Capozziello, Valerio
Faraoni
|
Fluid nature constrains Horndeski gravity
|
28 pages, 2 tables. Matches published version in General Relativity
and Gravitation
|
Gen.Rel.Grav. 55 (2023) 7, 84
|
10.1007/s10714-023-03128-1
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The elusive physical nature of Horndeski gravity is elucidated in a new
approach depicting this class of theories as a dissipative effective fluid.
Requiring the constitutive equations of the latter to be those of a Newtonian
fluid restricts the theory to only two disconnected subclasses of "viable"
Horndeski gravity. Therefore, a stress-energy tensor of Horndeski effective
fluid, linear in the first derivatives of the fluid's 4-velocity, is a
sufficient condition for gravitational waves to propagate at light speed. All
other Horndeski theories correspond to exotic non-Newtonian effective fluids.
|
[
{
"created": "Tue, 6 Sep 2022 18:00:05 GMT",
"version": "v1"
},
{
"created": "Thu, 13 Jul 2023 10:17:47 GMT",
"version": "v2"
}
] |
2023-07-14
|
[
[
"Miranda",
"Marcello",
""
],
[
"Vernieri",
"Daniele",
""
],
[
"Capozziello",
"Salvatore",
""
],
[
"Faraoni",
"Valerio",
""
]
] |
The elusive physical nature of Horndeski gravity is elucidated in a new approach depicting this class of theories as a dissipative effective fluid. Requiring the constitutive equations of the latter to be those of a Newtonian fluid restricts the theory to only two disconnected subclasses of "viable" Horndeski gravity. Therefore, a stress-energy tensor of Horndeski effective fluid, linear in the first derivatives of the fluid's 4-velocity, is a sufficient condition for gravitational waves to propagate at light speed. All other Horndeski theories correspond to exotic non-Newtonian effective fluids.
|
gr-qc/9606013
|
Roumen Borissov
|
Roumen Borissov
|
Graphical Evolution of Spin Network States
|
24 pages, 21 PostScript figures, uses epsfig.sty, Minor corrections
in the final formula in the main body of the paper and in the formula for the
Tetrahedral net in the Appendix
|
Phys.Rev. D55 (1997) 6099-6111
|
10.1103/PhysRevD.55.6099
|
TU-96/6-1
|
gr-qc hep-th
| null |
The evolution of spin network states in loop quantum gravity can be described
by introducing a time variable, defined by the surfaces of constant value of an
auxiliary scalar field. We regulate the Hamiltonian, generating such an
evolution, and evaluate its action both on edges and on vertices of the spin
network states. The analytical computations are carried out completely to yield
a finite, diffeomorphism invariant result. We use techniques from the
recoupling theory of colored graphs with trivalent vertices to evaluate the
graphical part of the Hamiltonian action. We show that the action on edges is
equivalent to a diffeomorphism transformation, while the action on vertices
adds new edges and re-routes the loops through the vertices.
|
[
{
"created": "Fri, 7 Jun 1996 17:18:41 GMT",
"version": "v1"
},
{
"created": "Mon, 10 Jun 1996 18:49:14 GMT",
"version": "v2"
},
{
"created": "Mon, 24 Mar 1997 20:20:09 GMT",
"version": "v3"
}
] |
2009-10-28
|
[
[
"Borissov",
"Roumen",
""
]
] |
The evolution of spin network states in loop quantum gravity can be described by introducing a time variable, defined by the surfaces of constant value of an auxiliary scalar field. We regulate the Hamiltonian, generating such an evolution, and evaluate its action both on edges and on vertices of the spin network states. The analytical computations are carried out completely to yield a finite, diffeomorphism invariant result. We use techniques from the recoupling theory of colored graphs with trivalent vertices to evaluate the graphical part of the Hamiltonian action. We show that the action on edges is equivalent to a diffeomorphism transformation, while the action on vertices adds new edges and re-routes the loops through the vertices.
|
1402.6592
|
Jose M Munoz-Castaneda
|
J. M. Munoz-Castaneda and M. Bordag
|
Quantum vacuum interaction between two cosmic strings revisited
|
Submitted to Phys Rev D
|
Phys. Rev. D 89, 065034 (2014)
|
10.1103/PhysRevD.89.065034
| null |
gr-qc hep-th math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We reconsider the quantum vacuum interaction energy between two straight
parallel cosmic strings. This problem was discussed several times in an
approach treating both strings perturbatively and treating only one
perturbatively. Here we point out that a simplifying assumption made in [1] can
be justified and show that, despite the global character of the background, the
perturbative approach delivers a correct result. We consider the applicability
of the scattering methods, developed in the past decade for the Casimir effect,
for the cosmic string and find it not applicable. We calculate the scattering
T-operator on one string. Finally, we consider the vacuum interaction of two
strings when each carries a two dimensional delta function potential.
|
[
{
"created": "Wed, 26 Feb 2014 16:23:51 GMT",
"version": "v1"
}
] |
2015-06-18
|
[
[
"Munoz-Castaneda",
"J. M.",
""
],
[
"Bordag",
"M.",
""
]
] |
We reconsider the quantum vacuum interaction energy between two straight parallel cosmic strings. This problem was discussed several times in an approach treating both strings perturbatively and treating only one perturbatively. Here we point out that a simplifying assumption made in [1] can be justified and show that, despite the global character of the background, the perturbative approach delivers a correct result. We consider the applicability of the scattering methods, developed in the past decade for the Casimir effect, for the cosmic string and find it not applicable. We calculate the scattering T-operator on one string. Finally, we consider the vacuum interaction of two strings when each carries a two dimensional delta function potential.
|
1504.00846
|
Hayato Motohashi
|
Hayato Motohashi, Jonathan White
|
Disformal invariance of curvature perturbation
|
15 pages; Improved Sec. IV, added Appendix B and discussion on the
invertibility of the disformal transformation in Sec. II; Improved discussion
in Secs. II and IV, matches published version in JCAP
|
JCAP 1602 (2016) 02, 065
|
10.1088/1475-7516/2016/02/065
|
RESCEU-8/15, KEK-TH-1802
|
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We show that under a general disformal transformation the linear comoving
curvature perturbation is not identically invariant, but is invariant on
superhorizon scales for any theory that is disformally related to Horndeski's
theory. The difference between disformally related curvature perturbations is
found to be given in terms of the comoving density perturbation associated with
a single canonical scalar field. In General Relativity it is well-known that
this quantity vanishes on superhorizon scales through the Poisson equation that
is obtained on combining the Hamiltonian and momentum constraints, and we
confirm that a similar result holds for any theory that is disformally related
to Horndeski's scalar-tensor theory so long as the invertibility condition for
the disformal transformation is satisfied. We also consider the curvature
perturbation at full nonlinear order in the unitary gauge, and find that it is
invariant under a general disformal transformation if we assume that an
attractor regime has been reached. Finally, we also discuss the counting of
degrees of freedom in theories disformally related to Horndeski's.
|
[
{
"created": "Thu, 2 Apr 2015 18:08:21 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Aug 2015 05:06:10 GMT",
"version": "v2"
},
{
"created": "Mon, 29 Feb 2016 23:00:36 GMT",
"version": "v3"
}
] |
2016-03-11
|
[
[
"Motohashi",
"Hayato",
""
],
[
"White",
"Jonathan",
""
]
] |
We show that under a general disformal transformation the linear comoving curvature perturbation is not identically invariant, but is invariant on superhorizon scales for any theory that is disformally related to Horndeski's theory. The difference between disformally related curvature perturbations is found to be given in terms of the comoving density perturbation associated with a single canonical scalar field. In General Relativity it is well-known that this quantity vanishes on superhorizon scales through the Poisson equation that is obtained on combining the Hamiltonian and momentum constraints, and we confirm that a similar result holds for any theory that is disformally related to Horndeski's scalar-tensor theory so long as the invertibility condition for the disformal transformation is satisfied. We also consider the curvature perturbation at full nonlinear order in the unitary gauge, and find that it is invariant under a general disformal transformation if we assume that an attractor regime has been reached. Finally, we also discuss the counting of degrees of freedom in theories disformally related to Horndeski's.
|
gr-qc/9907040
|
Dominic Clancy
|
James E. Lidsey, Carlos Romero, Reza Tavakol and Steve Rippl
|
On Applications of Campbell's Embedding Theorem
|
17 pages, standard Latex source
|
Class.Quant.Grav.14:865-879,1997
|
10.1088/0264-9381/14/4/005
| null |
gr-qc
| null |
A little known theorem due to Campbell is employed to establish the local
embedding of a wide class of 4-dimensional spacetimes in 5-dimensional
Ricci-flat spaces. An embedding for the class of n-dimensional Einstein spaces
is also found. The local nature of Campbell's theorem is highlighted by
studying the embedding of some lower-dimensional spaces.
|
[
{
"created": "Fri, 9 Jul 1999 14:21:39 GMT",
"version": "v1"
}
] |
2008-11-26
|
[
[
"Lidsey",
"James E.",
""
],
[
"Romero",
"Carlos",
""
],
[
"Tavakol",
"Reza",
""
],
[
"Rippl",
"Steve",
""
]
] |
A little known theorem due to Campbell is employed to establish the local embedding of a wide class of 4-dimensional spacetimes in 5-dimensional Ricci-flat spaces. An embedding for the class of n-dimensional Einstein spaces is also found. The local nature of Campbell's theorem is highlighted by studying the embedding of some lower-dimensional spaces.
|
1808.05522
|
Yuri Bonder
|
Yuri Bonder and Crist\'obal Corral
|
Is there any symmetry left in gravity theories with explicit Lorentz
violation?
|
For a special issue of the journal Symmetry on Broken Symmetry in
Curved Spacetime and Gravity. 8 pages
|
Symmetry 2018, 10(10), 433
|
10.3390/sym10100433
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
It is well known that a theory with explicit Lorentz violation is not
invariant under diffeomorphisms. On the other hand, for geometrical theories of
gravity, there are alternative transformations, which can be best defined
within the first-order formalism, and that can be regarded as a set of improved
diffeomorphisms. These symmetries are known as local translations and, among
other features, they are Lorentz covariant off shell. It is thus interesting to
study if theories with explicit Lorentz violation are invariant under local
translations. In this work, an example of such a theory, known as the minimal
gravity sector of the Standard Model Extension, is analyzed. Using a robust
algorithm, it is shown that local translations are not a symmetry of the
theory. It remains to be seen if local translations are spontaneously broken
under spontaneous Lorentz violation, which are regarded as a more natural
alternative when spacetime is dynamic.
|
[
{
"created": "Thu, 16 Aug 2018 14:47:53 GMT",
"version": "v1"
},
{
"created": "Tue, 18 Sep 2018 03:25:46 GMT",
"version": "v2"
}
] |
2018-10-10
|
[
[
"Bonder",
"Yuri",
""
],
[
"Corral",
"Cristóbal",
""
]
] |
It is well known that a theory with explicit Lorentz violation is not invariant under diffeomorphisms. On the other hand, for geometrical theories of gravity, there are alternative transformations, which can be best defined within the first-order formalism, and that can be regarded as a set of improved diffeomorphisms. These symmetries are known as local translations and, among other features, they are Lorentz covariant off shell. It is thus interesting to study if theories with explicit Lorentz violation are invariant under local translations. In this work, an example of such a theory, known as the minimal gravity sector of the Standard Model Extension, is analyzed. Using a robust algorithm, it is shown that local translations are not a symmetry of the theory. It remains to be seen if local translations are spontaneously broken under spontaneous Lorentz violation, which are regarded as a more natural alternative when spacetime is dynamic.
|
gr-qc/0408077
|
Richard Price
|
Richard H. Price and Lior M. Burko
|
Late time tails from momentarily stationary, compact initial data in
Schwarzschild spacetimes
|
7 pages, 5 figures
|
Phys.Rev. D70 (2004) 084039
|
10.1103/PhysRevD.70.084039
| null |
gr-qc
| null |
An L-pole perturbation in Schwarzschild spacetime generally falls off at late
times t as t^{-2L-3}. It has recently been pointed out by Karkowski,
Swierczynski and Malec, that for initial data that is of compact support, and
is initially momentarily static, the late-time behavior is different, going as
t^{-2L-4}. By considering the Laplace transforms of the fields, we show here
why the momentarily stationary case is exceptional. We also explain, using a
time-domain description, the special features of the time development in this
exceptional case.
|
[
{
"created": "Mon, 23 Aug 2004 15:13:23 GMT",
"version": "v1"
}
] |
2009-11-10
|
[
[
"Price",
"Richard H.",
""
],
[
"Burko",
"Lior M.",
""
]
] |
An L-pole perturbation in Schwarzschild spacetime generally falls off at late times t as t^{-2L-3}. It has recently been pointed out by Karkowski, Swierczynski and Malec, that for initial data that is of compact support, and is initially momentarily static, the late-time behavior is different, going as t^{-2L-4}. By considering the Laplace transforms of the fields, we show here why the momentarily stationary case is exceptional. We also explain, using a time-domain description, the special features of the time development in this exceptional case.
|
gr-qc/0609099
|
Petarpa Boonserm
|
Petarpa Boonserm (Victoria University of Wellington), Matt Visser
(Victoria University of Wellington), and Silke Weinfurtner (Victoria
University of Wellington)
|
Solution generating theorems: perfect fluid spheres and the TOV equation
|
3 pages, 0 figures, to appear in the proceedings of the Eleventh
Marcel Grossmann Meeting on General Relativity (MG11), 23 - 29 July, 2006,
Berlin, Germany
| null | null | null |
gr-qc
| null |
We report several new transformation theorems that map perfect fluid spheres
into perfect fluid spheres. In addition, we report new ``solution generating''
theorems for the TOV, whereby any given solution can be ``deformed'' to a new
solution.
|
[
{
"created": "Fri, 22 Sep 2006 02:51:21 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Boonserm",
"Petarpa",
"",
"Victoria University of Wellington"
],
[
"Visser",
"Matt",
"",
"Victoria University of Wellington"
],
[
"Weinfurtner",
"Silke",
"",
"Victoria\n University of Wellington"
]
] |
We report several new transformation theorems that map perfect fluid spheres into perfect fluid spheres. In addition, we report new ``solution generating'' theorems for the TOV, whereby any given solution can be ``deformed'' to a new solution.
|
1702.05786
|
Waleed El Hanafy
|
W. El Hanafy and G.G.L. Nashed
|
Generic Phase Portrait Analysis of the Finite-time Singularities and
Generalized Teleparallel Gravity
|
To be published in Chinese Physics C (Accepted version)
|
Chinese Physics C Vol. 41, No. 12 (2017) 125103
|
10.1088/1674-1137/41/12/125103
| null |
gr-qc astro-ph.CO hep-ph hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We analyze the common four types of the finite-time singularities using a
generic framework of the phase portrait geometric approach. This technique
requires that the Friedmann system to be written as a one dimensional
autonomous system. We employ a scale factor that has been used widely in
literature to realize the four finite-time singularity types, then we show a
detailed discussion for each case showing possible novel models. Moreover, we
show how different singularity types can play essential roles in different
cosmological scenarios. Among several modified gravity theories, we show that
the f (T) cosmology is in comfort with the phase portrait analysis, since the
field equations include Hubble derivatives only up to first order. Therefore,
we reconstruct the f (T) theory which generates these phase portraits. We also
perform a complementary analysis using the effective equation of state.
Furthermore, we investigate the role of the torsion fluid in realizing the
cosmic singularities.
|
[
{
"created": "Sun, 19 Feb 2017 19:23:50 GMT",
"version": "v1"
},
{
"created": "Wed, 4 Oct 2017 17:39:42 GMT",
"version": "v2"
}
] |
2017-11-07
|
[
[
"Hanafy",
"W. El",
""
],
[
"Nashed",
"G. G. L.",
""
]
] |
We analyze the common four types of the finite-time singularities using a generic framework of the phase portrait geometric approach. This technique requires that the Friedmann system to be written as a one dimensional autonomous system. We employ a scale factor that has been used widely in literature to realize the four finite-time singularity types, then we show a detailed discussion for each case showing possible novel models. Moreover, we show how different singularity types can play essential roles in different cosmological scenarios. Among several modified gravity theories, we show that the f (T) cosmology is in comfort with the phase portrait analysis, since the field equations include Hubble derivatives only up to first order. Therefore, we reconstruct the f (T) theory which generates these phase portraits. We also perform a complementary analysis using the effective equation of state. Furthermore, we investigate the role of the torsion fluid in realizing the cosmic singularities.
|
1008.1958
|
Mauricio Bellini
|
Mauricio Bellini (IFIMAR, CONICET & Mar del Plata University)
|
Fierz-Pauli equation for massive gravitons from Induced Matter theory of
gravity
|
9 pages, no figures, version accepted in Phys. Lett. B
|
Phys.Lett.B696:183-185,2011
|
10.1016/j.physletb.2010.12.054
| null |
gr-qc hep-ph hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Starting with a 5D physical vacuum described by a 5D Ricci-flat background
metric, we study the emergence of gravitational waves (GW) from the Induce
Matter (IM) theory of gravity. We obtain the equation of motion for GW on an 4D
curved spacetime which has the form of a Fierz-Pauli one. In our model the mass
of gravitons $m_g$ is induced by a static foliation on the noncompact
space-like extra dimension and the source-term is originated in the interaction
of the GW with the induced connections of the background 5D metric. Here,
relies the main difference of this formalism with the original Fierz-Pauli one.
|
[
{
"created": "Wed, 11 Aug 2010 17:39:54 GMT",
"version": "v1"
},
{
"created": "Thu, 9 Sep 2010 18:41:13 GMT",
"version": "v2"
},
{
"created": "Fri, 19 Nov 2010 11:18:09 GMT",
"version": "v3"
},
{
"created": "Tue, 28 Dec 2010 11:14:38 GMT",
"version": "v4"
}
] |
2011-01-17
|
[
[
"Bellini",
"Mauricio",
"",
"IFIMAR, CONICET & Mar del Plata University"
]
] |
Starting with a 5D physical vacuum described by a 5D Ricci-flat background metric, we study the emergence of gravitational waves (GW) from the Induce Matter (IM) theory of gravity. We obtain the equation of motion for GW on an 4D curved spacetime which has the form of a Fierz-Pauli one. In our model the mass of gravitons $m_g$ is induced by a static foliation on the noncompact space-like extra dimension and the source-term is originated in the interaction of the GW with the induced connections of the background 5D metric. Here, relies the main difference of this formalism with the original Fierz-Pauli one.
|
0904.4418
|
Bernd Bruegmann
|
Bernd Bruegmann
|
Schwarzschild black hole as moving puncture in isotropic coordinates
|
11 pages, 5 figures, pdflatex
|
Gen.Rel.Grav.41:2131-2151,2009
|
10.1007/s10714-009-0818-6
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The success of the moving puncture method for the numerical simulation of
black hole systems can be partially explained by the properties of stationary
solutions of the 1+log coordinate condition. We compute stationary 1+log slices
of the Schwarzschild spacetime in isotropic coordinates in order to investigate
the coordinate singularity that the numerical methods have to handle at the
puncture. We present an alternative integration method to obtain isotropic
coordinates that simplifies numerical integration and that gives direct access
to a local expansion in the isotropic radius near the puncture. Numerical
results have shown that certain quantities are well approximated by a function
linear in the isotropic radius near the puncture, while here we show that in
some cases the isotropic radius appears with an exponent that is close to but
unequal to one.
|
[
{
"created": "Tue, 28 Apr 2009 14:56:46 GMT",
"version": "v1"
}
] |
2010-03-26
|
[
[
"Bruegmann",
"Bernd",
""
]
] |
The success of the moving puncture method for the numerical simulation of black hole systems can be partially explained by the properties of stationary solutions of the 1+log coordinate condition. We compute stationary 1+log slices of the Schwarzschild spacetime in isotropic coordinates in order to investigate the coordinate singularity that the numerical methods have to handle at the puncture. We present an alternative integration method to obtain isotropic coordinates that simplifies numerical integration and that gives direct access to a local expansion in the isotropic radius near the puncture. Numerical results have shown that certain quantities are well approximated by a function linear in the isotropic radius near the puncture, while here we show that in some cases the isotropic radius appears with an exponent that is close to but unequal to one.
|
gr-qc/0512069
|
Daniele Oriti
|
Daniele Oriti
|
Generalised group field theories and quantum gravity transition
amplitudes
|
RevTeX; 6 pages, 2 figures
|
Phys.Rev. D73 (2006) 061502
|
10.1103/PhysRevD.73.061502
|
DAMTP-2005-127
|
gr-qc
| null |
We construct a generalised formalism for group field theories, in which the
domain of the field is extended to include additional proper time variables, as
well as their conjugate mass variables. This formalism allows for different
types of quantum gravity transition amplitudes in perturbative expansion, and
we show how both causal spin foam models and the usual a-causal ones can be
derived from it, within a sum over triangulations of all topologies. We also
highlight the relation of the so-derived causal transition amplitudes with
simplicial gravity actions.
|
[
{
"created": "Mon, 12 Dec 2005 17:23:35 GMT",
"version": "v1"
}
] |
2009-11-11
|
[
[
"Oriti",
"Daniele",
""
]
] |
We construct a generalised formalism for group field theories, in which the domain of the field is extended to include additional proper time variables, as well as their conjugate mass variables. This formalism allows for different types of quantum gravity transition amplitudes in perturbative expansion, and we show how both causal spin foam models and the usual a-causal ones can be derived from it, within a sum over triangulations of all topologies. We also highlight the relation of the so-derived causal transition amplitudes with simplicial gravity actions.
|
1604.02328
|
Sercan Cikintoglu
|
Sava\c{s} Arapo\u{g}lu, Sercan \c{C}{\i}k{\i}nto\u{g}lu, K. Yavuz
Ek\c{s}i
|
Relativistic stars in Starobinsky gravity with the matched asymptotic
expansions method
|
10 pages, 3 figures, matches the published version in PRD
|
Phys. Rev. D 96, 084040 (2017)
|
10.1103/PhysRevD.96.084040
| null |
gr-qc astro-ph.HE
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study the structure of relativistic stars in $\mathcal{R}+\alpha
\mathcal{R}^{2}$ theory using the method of matched asymptotic expansion to
handle the higher order derivatives in field equations arising from the higher
order curvature term. We find solutions, parametrized by $\alpha$, for uniform
density stars. We obtain the mass-radius relations and study the dependence of
maximum mass on $\alpha$. We find that $M_{\max}$ is almost linearly
proportional to $\alpha$. For each $\alpha$ the maximum mass configuration has
the biggest compactness parameter ($\eta = GM/Rc^2$), and we argue that the
general relativistic stellar configuration corresponding to $\alpha=0$ is the
least compact among these.
|
[
{
"created": "Thu, 7 Apr 2016 08:18:39 GMT",
"version": "v1"
},
{
"created": "Thu, 14 Apr 2016 13:41:46 GMT",
"version": "v2"
},
{
"created": "Fri, 15 Apr 2016 13:59:01 GMT",
"version": "v3"
},
{
"created": "Mon, 18 Sep 2017 14:30:01 GMT",
"version": "v4"
},
{
"created": "Sun, 22 Oct 2017 20:56:55 GMT",
"version": "v5"
}
] |
2017-10-24
|
[
[
"Arapoğlu",
"Savaş",
""
],
[
"Çıkıntoğlu",
"Sercan",
""
],
[
"Ekşi",
"K. Yavuz",
""
]
] |
We study the structure of relativistic stars in $\mathcal{R}+\alpha \mathcal{R}^{2}$ theory using the method of matched asymptotic expansion to handle the higher order derivatives in field equations arising from the higher order curvature term. We find solutions, parametrized by $\alpha$, for uniform density stars. We obtain the mass-radius relations and study the dependence of maximum mass on $\alpha$. We find that $M_{\max}$ is almost linearly proportional to $\alpha$. For each $\alpha$ the maximum mass configuration has the biggest compactness parameter ($\eta = GM/Rc^2$), and we argue that the general relativistic stellar configuration corresponding to $\alpha=0$ is the least compact among these.
|
2101.08261
|
V. G. Gurzadyan
|
A. Stepanian, Sh. Khlghatyan, V.G. Gurzadyan
|
Black hole shadow to probe modified gravity
|
7 pages, Eur. Phys. J. Plus (in press)
|
Eur. Phys. J. Plus 136, 127 (2021)
|
10.1140/epjp/s13360-021-01119-2
| null |
gr-qc astro-ph.CO
|
http://creativecommons.org/licenses/by/4.0/
|
We study the black hole's shadow for Schwarzschild - de Sitter and Kerr - de
Sitter metrics with the contribution of the cosmological constant \Lambda.
Based on the reported parameters of the M87* black hole shadow we obtain
constraints for the $\Lambda$ and show the agreement with the cosmological
data. It is shown that, the coupling of the \Lambda-term with the spin
parameter reveals peculiarities for the photon spheres and hence for the
shadows. Within the parametrized post-Newtonian formalism the constraint for
the corresponding \Lambda-determined parameter is obtained.
|
[
{
"created": "Wed, 20 Jan 2021 03:17:17 GMT",
"version": "v1"
}
] |
2021-01-29
|
[
[
"Stepanian",
"A.",
""
],
[
"Khlghatyan",
"Sh.",
""
],
[
"Gurzadyan",
"V. G.",
""
]
] |
We study the black hole's shadow for Schwarzschild - de Sitter and Kerr - de Sitter metrics with the contribution of the cosmological constant \Lambda. Based on the reported parameters of the M87* black hole shadow we obtain constraints for the $\Lambda$ and show the agreement with the cosmological data. It is shown that, the coupling of the \Lambda-term with the spin parameter reveals peculiarities for the photon spheres and hence for the shadows. Within the parametrized post-Newtonian formalism the constraint for the corresponding \Lambda-determined parameter is obtained.
|
gr-qc/9812074
|
Sergei N. Vergeles
|
S.N. Vergeles (The Landau Institute for Theoretical Physics, Russian
Academy of Sciences.)
|
The anomaly-free quantization of two-dimensional relativistic string. I
|
LaTeX, 19 pages, no figures
|
J.Exp.Theor.Phys. 86 (1998) 854-859; Zh.Eksp.Teor.Fiz. 113 (1998)
1566-1578
|
10.1134/1.558556
| null |
gr-qc
| null |
An anomaly-free quantum theory of a relativistic string is constructed in
two-dimensional space-time. The states of the string are found to be similar to
the states of a massless chiral quantum particle. This result is obtained by
generalizing the concept of an ``operator'' in quantum field theory.
|
[
{
"created": "Mon, 21 Dec 1998 09:48:37 GMT",
"version": "v1"
}
] |
2015-06-25
|
[
[
"Vergeles",
"S. N.",
"",
"The Landau Institute for Theoretical Physics, Russian\n Academy of Sciences."
]
] |
An anomaly-free quantum theory of a relativistic string is constructed in two-dimensional space-time. The states of the string are found to be similar to the states of a massless chiral quantum particle. This result is obtained by generalizing the concept of an ``operator'' in quantum field theory.
|
2108.10633
|
Theo Verwimp
|
Theo Verwimp
|
On higher dimensional gravity: the Lagrangian, its dimensional reduction
and a cosmological model
|
11 pages, a typo in equation (3.17) of the original publication has
been corrected
|
Class. Quantum Grav. 6 (1989) 1655-1663
| null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
By dimensional reduction of the Lovelock Lagrangian, effective
four-dimensional field equations and expressions for the cosmological and
gravitational constants are obtained. A cosmological model is discussed with
the n-torus as internal space.
|
[
{
"created": "Tue, 24 Aug 2021 10:31:51 GMT",
"version": "v1"
}
] |
2021-08-25
|
[
[
"Verwimp",
"Theo",
""
]
] |
By dimensional reduction of the Lovelock Lagrangian, effective four-dimensional field equations and expressions for the cosmological and gravitational constants are obtained. A cosmological model is discussed with the n-torus as internal space.
|
2204.02026
|
Pankaj Sheoran
|
Sanjar Shaymatov, Pankaj Sheoran, Ricardo Becerril, Ulises Nucamendi,
Bobomurat Ahmedov
|
Efficiency of Penrose process in spacetime of axially symmetric
magnetized Reissner-Nordstr\"{o}m black hole
|
10 pages, 6 captioned figures. Updated to match with the PRD version
|
Phys. Rev. D 106, 024039 (2022)
|
10.1103/PhysRevD.106.024039
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, we investigate the Penrose process in the purlieus of the
axially symmetric magnetized Reissner-Nordstr\"{o}m black hole for both neutral
and charged particles. We start with the study of the geometry of the black
hole and find the regions where the $g_{tt}$ component of the metric tensor is
positive (i.e., $g_{tt}>0$). It is interestingly found that the condition
$g_{tt}>0$ is fulfilled not only close to the event horizon known as the
ergosphere but also far away from the event horizon in the silhouette of
potential wells. We also show that as the dimensionless magnetic field $B$
increases the silhouette of potential wells for which $g_{tt}>0$ grows
correspondingly and eventually merges with the ergoregion when $B\gtrsim 1.6$.
Finally, we investigate the efficiency of the Penrose process for the axially
symmetric magnetized black hole case and bring out the effect of the magnetic
field on it. Further, we also compare our results with the one for Kerr black
hole. We show that when the charge $Q$ of the black hole is kept constant, the
efficiency of the energy extraction process for the case of {a neutral particle
(i.e., $q/m=0$) first increases and then begins to decrease with rise in the
value of $B$ field, in contrast to Kerr black hole where it always increases as
the rotation parameter grows. However, for the case of a charged particle
(i.e., $q\neq 0$) the efficiency always increases with the rise in the $B$
field and can go over $100\%$, when both $B$ and $q/m$ are large enough (say
$B\approx1$ and $q/m>2.2$)}. It is worth noting that the existence of regions
away from the horizon where $g_{tt}>0$ also favors the energy-extraction
process away from the effect of the black hole. However, the energy extraction
from these regions is pure consequence of the magnetic field.
|
[
{
"created": "Tue, 5 Apr 2022 07:05:02 GMT",
"version": "v1"
},
{
"created": "Mon, 25 Jul 2022 10:05:10 GMT",
"version": "v2"
}
] |
2022-07-26
|
[
[
"Shaymatov",
"Sanjar",
""
],
[
"Sheoran",
"Pankaj",
""
],
[
"Becerril",
"Ricardo",
""
],
[
"Nucamendi",
"Ulises",
""
],
[
"Ahmedov",
"Bobomurat",
""
]
] |
In this paper, we investigate the Penrose process in the purlieus of the axially symmetric magnetized Reissner-Nordstr\"{o}m black hole for both neutral and charged particles. We start with the study of the geometry of the black hole and find the regions where the $g_{tt}$ component of the metric tensor is positive (i.e., $g_{tt}>0$). It is interestingly found that the condition $g_{tt}>0$ is fulfilled not only close to the event horizon known as the ergosphere but also far away from the event horizon in the silhouette of potential wells. We also show that as the dimensionless magnetic field $B$ increases the silhouette of potential wells for which $g_{tt}>0$ grows correspondingly and eventually merges with the ergoregion when $B\gtrsim 1.6$. Finally, we investigate the efficiency of the Penrose process for the axially symmetric magnetized black hole case and bring out the effect of the magnetic field on it. Further, we also compare our results with the one for Kerr black hole. We show that when the charge $Q$ of the black hole is kept constant, the efficiency of the energy extraction process for the case of {a neutral particle (i.e., $q/m=0$) first increases and then begins to decrease with rise in the value of $B$ field, in contrast to Kerr black hole where it always increases as the rotation parameter grows. However, for the case of a charged particle (i.e., $q\neq 0$) the efficiency always increases with the rise in the $B$ field and can go over $100\%$, when both $B$ and $q/m$ are large enough (say $B\approx1$ and $q/m>2.2$)}. It is worth noting that the existence of regions away from the horizon where $g_{tt}>0$ also favors the energy-extraction process away from the effect of the black hole. However, the energy extraction from these regions is pure consequence of the magnetic field.
|
gr-qc/0603026
|
Roberto Casadio
|
R. Casadio, F. Finelli, A. Kamenshchik, M. Luzzi, G. Venturi
|
Method of comparison equations for cosmological perturbations
|
20 pages, 10 figures
|
JCAP0604:011,2006
|
10.1088/1475-7516/2006/04/011
| null |
gr-qc astro-ph hep-th
| null |
We apply the method of comparison equations to study cosmological
perturbations during inflation, obtaining the full power spectra of scalar and
tensor perturbations to first and to second order in the slow-roll parameters.
We compare our results with those derived by means of other methods, in
particular the Green's function method and the improved WKB approximation, and
find agreement for the slow-roll structure. The method of comparison equations,
just as the improved WKB approximation, can however be applied to more general
situations where the slow-roll approximation fails.
|
[
{
"created": "Wed, 8 Mar 2006 15:40:02 GMT",
"version": "v1"
}
] |
2009-11-11
|
[
[
"Casadio",
"R.",
""
],
[
"Finelli",
"F.",
""
],
[
"Kamenshchik",
"A.",
""
],
[
"Luzzi",
"M.",
""
],
[
"Venturi",
"G.",
""
]
] |
We apply the method of comparison equations to study cosmological perturbations during inflation, obtaining the full power spectra of scalar and tensor perturbations to first and to second order in the slow-roll parameters. We compare our results with those derived by means of other methods, in particular the Green's function method and the improved WKB approximation, and find agreement for the slow-roll structure. The method of comparison equations, just as the improved WKB approximation, can however be applied to more general situations where the slow-roll approximation fails.
|
1810.07671
|
Noah Graham
|
Noah Graham
|
Schwarzschild Quantum Fluctuations from Regge-Wheeler Scattering
|
12 pages, 4 .eps figures; v2: fixed typos, added example calculation;
v3: fixed typo (correct sign in Eq. A7); v4: fixed typo (missing factor in
Eq. 28), added clarification of techniques for numerical calculation
|
Phys. Rev. D 99, 025005 (2019)
|
10.1103/PhysRevD.99.025005
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We apply a multichannel variable phase method to scattering from
Regge-Wheeler potentials. Using a reduced version of the WKB subtraction
developed by Candelas and Howard, this approach allows for efficient numerical
calculations of scattering data for imaginary wave number, making it possible
to compute quantum expectation values in a Schwarzschild curved spacetime
background through Wick rotation to the imaginary frequency axis. These
scattering theory techniques are also potentially applicable to a variety of
other problems involving wave propagation in curved spacetime.
|
[
{
"created": "Wed, 17 Oct 2018 17:07:31 GMT",
"version": "v1"
},
{
"created": "Tue, 8 Jan 2019 13:37:28 GMT",
"version": "v2"
},
{
"created": "Wed, 26 Jul 2023 14:53:24 GMT",
"version": "v3"
},
{
"created": "Tue, 8 Aug 2023 20:18:39 GMT",
"version": "v4"
}
] |
2023-08-10
|
[
[
"Graham",
"Noah",
""
]
] |
We apply a multichannel variable phase method to scattering from Regge-Wheeler potentials. Using a reduced version of the WKB subtraction developed by Candelas and Howard, this approach allows for efficient numerical calculations of scattering data for imaginary wave number, making it possible to compute quantum expectation values in a Schwarzschild curved spacetime background through Wick rotation to the imaginary frequency axis. These scattering theory techniques are also potentially applicable to a variety of other problems involving wave propagation in curved spacetime.
|
2002.12526
|
Todd Oliynyk
|
Todd A. Oliynyk
|
Future global stability for relativistic perfect fluids with linear
equations of state $p=K\rho$ where $1/3<K<1/2$
|
Comments typos corrected; agrees with the published version
|
SIAM J. Math. Anal. 53 (2021), 4118-4141
|
10.1137/20M1361195
| null |
gr-qc math.AP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We establish the future stability of nonlinear perturbations of a class of
homogeneous solutions to the relativistic Euler equations with a linear
equation of state $p=K\rho$ on exponentially expanding FLRW spacetimes for the
equation of state parameter values $1/3 < K < 1/2$.
|
[
{
"created": "Fri, 28 Feb 2020 03:36:08 GMT",
"version": "v1"
},
{
"created": "Wed, 19 Aug 2020 11:18:07 GMT",
"version": "v2"
},
{
"created": "Mon, 31 May 2021 05:46:37 GMT",
"version": "v3"
}
] |
2021-07-28
|
[
[
"Oliynyk",
"Todd A.",
""
]
] |
We establish the future stability of nonlinear perturbations of a class of homogeneous solutions to the relativistic Euler equations with a linear equation of state $p=K\rho$ on exponentially expanding FLRW spacetimes for the equation of state parameter values $1/3 < K < 1/2$.
|
1311.6697
|
S Habib Mazharimousavi
|
S. Habib Mazharimousavi and M. Halilsoy
|
Thin-shell wormholes supported by total normal matter
|
5 pages, 5 figures, final version published in EPJC
|
Eur. Phys. J. C (2014) 74:3067
|
10.1140/epjc/s10052-014-3067-0
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The Zipoy-Voorhees-Weyl (ZVW) spacetime characterized by mass ($M$) and
oblateness ($\delta $) is proposed in the construction of viable thin-shell
wormholes (TSWs). Departure from spherical / cylindrical symmetry yields
positive total energy in spite of the fact that local energy density may take
negative values. We show that oblateness of the bumpy sources / black holes can
be incorporated as a new degree of freedom that may play role in the resolution
of the exotic matter problem in TSWs. Small velocity perturbation reveals,
however, that the resulting TSW is unstable.
|
[
{
"created": "Mon, 25 Nov 2013 12:04:52 GMT",
"version": "v1"
},
{
"created": "Tue, 11 Mar 2014 16:22:39 GMT",
"version": "v2"
},
{
"created": "Mon, 29 Sep 2014 05:48:06 GMT",
"version": "v3"
}
] |
2014-09-30
|
[
[
"Mazharimousavi",
"S. Habib",
""
],
[
"Halilsoy",
"M.",
""
]
] |
The Zipoy-Voorhees-Weyl (ZVW) spacetime characterized by mass ($M$) and oblateness ($\delta $) is proposed in the construction of viable thin-shell wormholes (TSWs). Departure from spherical / cylindrical symmetry yields positive total energy in spite of the fact that local energy density may take negative values. We show that oblateness of the bumpy sources / black holes can be incorporated as a new degree of freedom that may play role in the resolution of the exotic matter problem in TSWs. Small velocity perturbation reveals, however, that the resulting TSW is unstable.
|
gr-qc/9511016
|
Steve F. Rippl
|
Steve Rippl, Carlos Romero and Reza Tavakol
|
$D$-Dimensional Gravity from $(D+1)$ Dimensions
|
11 pages, latex, published in CQG vol. 12 no. 10
|
Class.Quant.Grav. 12 (1995) 2411-2422
|
10.1088/0264-9381/12/10/004
| null |
gr-qc
| null |
We generalise Wesson's procedure, whereby vacuum $(4+1)-$dimensional field
equations give rise to $(3+1)-$dimensional equations with sources, to arbitrary
dimensions. We then employ this generalisation to relate the usual
$(3+1)-$dimensional vacuum field equations to $(2+1)-$dimensional field
equations with sources and derive the analogues of the classes of solutions
obtained by Ponce de Leon. This way of viewing lower dimensional gravity
theories can be of importance in establishing a relationship between such
theories and the usual 4-dimensional general relativity, as well as giving a
way of producing exact solutions in $(2+1)$ dimensions that are naturally
related to the vacuum $(3+1)-$dimensional solutions. An outcome of this
correspondence, regarding the nature of lower dimensional gravity, is that the
intuitions obtained in $(3+1)$ dimensions may not be automatically
transportable to lower dimensions.
We also extend a number of physically motivated solutions studied by Wesson
and Ponce de Leon to $(D+1)$ dimensions and employ the equivalence between the
$(D+1)$ Kaluza-Klein theories with empty $D-$dimensional Brans-Dicke theories
(with $\omega=0$) to throw some light on the solutions derived by these
authors.
|
[
{
"created": "Fri, 3 Nov 1995 14:08:16 GMT",
"version": "v1"
}
] |
2016-08-31
|
[
[
"Rippl",
"Steve",
""
],
[
"Romero",
"Carlos",
""
],
[
"Tavakol",
"Reza",
""
]
] |
We generalise Wesson's procedure, whereby vacuum $(4+1)-$dimensional field equations give rise to $(3+1)-$dimensional equations with sources, to arbitrary dimensions. We then employ this generalisation to relate the usual $(3+1)-$dimensional vacuum field equations to $(2+1)-$dimensional field equations with sources and derive the analogues of the classes of solutions obtained by Ponce de Leon. This way of viewing lower dimensional gravity theories can be of importance in establishing a relationship between such theories and the usual 4-dimensional general relativity, as well as giving a way of producing exact solutions in $(2+1)$ dimensions that are naturally related to the vacuum $(3+1)-$dimensional solutions. An outcome of this correspondence, regarding the nature of lower dimensional gravity, is that the intuitions obtained in $(3+1)$ dimensions may not be automatically transportable to lower dimensions. We also extend a number of physically motivated solutions studied by Wesson and Ponce de Leon to $(D+1)$ dimensions and employ the equivalence between the $(D+1)$ Kaluza-Klein theories with empty $D-$dimensional Brans-Dicke theories (with $\omega=0$) to throw some light on the solutions derived by these authors.
|
2304.00940
|
Syed Masood A. S. Bukhari
|
Syed Masood A. S. Bukhari, Behnam Pourhassan, Houcine Aounallah,
Li-Gang Wang
|
On the microstructure of higher-dimensional Reissner-Nordstr\"om black
holes in quantum regime
|
22 pages, 14 figures
|
Class.Quant.Grav. 40 (2023) 22, 225007
|
10.1088/1361-6382/acffa0
| null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
Thermodynamic Riemannian geometry provides great insights into the
microscopic structure of black holes (BHs). One such example is the Ruppeiner
geometry which is the metric space comprising the second derivatives of entropy
with respect to other extensive variables of the system. Reissner-Nordstr\"om
black holes (RNBHs) are known to be endowed with a flat Ruppeiner geometry for
all higher spacetime dimensions. However this holds true if one invokes
classical gravity where the semi-classical Bekenstein-Hawking entropy best
describes the thermodynamics of the system. If the much deeper quantum gravity
and string theories entail modifications to BH entropy, this prompts the
question whether the Ruppeiner flatness associated with higher dimensional
RNBHs still persists. We investigate this problem by considering
non-perturbative (exponential) and perturbative (logarithmic) modifications to
BH entropy of a $5$D RNBH. We find that while the case is so for larger
(classical) geometries, the situation is radically altered for smaller
(quantum) geometries. Namely, we show surprising emergence of multiple phase
transitions that depend on the choice of extent of corrections to BH entropy
and charge. Our consideration involves differentiated extremal and non-extremal
geometric scales corresponding to the validity regime of corrections to
entropy. More emphasis is laid on the exponential case as the contributions
become highly non-trivial on small scales. An essential critical mass scale
arises in this case that marks the onset of these phase transitions while the
BH diminishes in size via Hawking evaporation. We contend that this critical
value of mass perhaps best translates as the epoch of a classical to quantum BH
phase transition.
|
[
{
"created": "Mon, 3 Apr 2023 12:54:16 GMT",
"version": "v1"
},
{
"created": "Tue, 11 Apr 2023 15:40:37 GMT",
"version": "v2"
},
{
"created": "Sat, 8 Jul 2023 04:20:04 GMT",
"version": "v3"
}
] |
2023-12-15
|
[
[
"Bukhari",
"Syed Masood A. S.",
""
],
[
"Pourhassan",
"Behnam",
""
],
[
"Aounallah",
"Houcine",
""
],
[
"Wang",
"Li-Gang",
""
]
] |
Thermodynamic Riemannian geometry provides great insights into the microscopic structure of black holes (BHs). One such example is the Ruppeiner geometry which is the metric space comprising the second derivatives of entropy with respect to other extensive variables of the system. Reissner-Nordstr\"om black holes (RNBHs) are known to be endowed with a flat Ruppeiner geometry for all higher spacetime dimensions. However this holds true if one invokes classical gravity where the semi-classical Bekenstein-Hawking entropy best describes the thermodynamics of the system. If the much deeper quantum gravity and string theories entail modifications to BH entropy, this prompts the question whether the Ruppeiner flatness associated with higher dimensional RNBHs still persists. We investigate this problem by considering non-perturbative (exponential) and perturbative (logarithmic) modifications to BH entropy of a $5$D RNBH. We find that while the case is so for larger (classical) geometries, the situation is radically altered for smaller (quantum) geometries. Namely, we show surprising emergence of multiple phase transitions that depend on the choice of extent of corrections to BH entropy and charge. Our consideration involves differentiated extremal and non-extremal geometric scales corresponding to the validity regime of corrections to entropy. More emphasis is laid on the exponential case as the contributions become highly non-trivial on small scales. An essential critical mass scale arises in this case that marks the onset of these phase transitions while the BH diminishes in size via Hawking evaporation. We contend that this critical value of mass perhaps best translates as the epoch of a classical to quantum BH phase transition.
|
gr-qc/0303056
|
Norbert Van den Bergh
|
Norbert Van den Bergh
|
Tidal effects cannot be absent in a vacuum
|
4 pages, typos corrected
|
Class.Quant.Grav. 20 (2003) L165-L168
|
10.1088/0264-9381/20/11/103
| null |
gr-qc
| null |
It is shown that there are no vacuum space-times (with or without
cosmological constant) for which the Weyl-tensor is purely gravito-magnetic
with respect to a congruence of freely falling observers.
|
[
{
"created": "Fri, 14 Mar 2003 15:22:54 GMT",
"version": "v1"
},
{
"created": "Mon, 17 Mar 2003 10:54:47 GMT",
"version": "v2"
}
] |
2009-11-10
|
[
[
"Bergh",
"Norbert Van den",
""
]
] |
It is shown that there are no vacuum space-times (with or without cosmological constant) for which the Weyl-tensor is purely gravito-magnetic with respect to a congruence of freely falling observers.
|
2106.12542
|
J\'unior Diniz Toniato
|
J\'unior D. Toniato and Davi C. Rodrigues
|
Post-Newtonian $\gamma$-like parameters and the gravitational slip in
scalar-tensor and $f(R)$ theories
|
16 pages, published version in PRD
|
Phys. Rev. D 104, 044020 (2021)
|
10.1103/PhysRevD.104.044020
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We review the fundamentals and highlight the differences between some
commonly used definitions for the PPN gamma parameter ($\gamma$) and the
gravitational slip ($\eta$). Here we stress the usefulness of a gamma-like
parameter used by Berry and Gair ($\gamma_{\scriptscriptstyle \Sigma}$) that
parametrizes the bending of light and the Shapiro time delay in situations in
which the standard $\gamma$ cannot be promptly used. First we apply our
considerations to two well known cases, but for which some conflicting results
can be found: massive Brans-Dicke gravity and $f(R)$ gravity (both the metric
and the Palatini versions). Although the slip parameter is always well defined,
it has in general no direct relation to either light deflection or the Shapiro
time delay, hence care should be taken on imposing the PPN $\gamma$ bounds on
the slip. We stress that, for any system with a well posed Newtonian limit,
Palatini $f(R)$ theories always have $\gamma = 1$; while metric $f(R)$ theories
can only have two values: either 1 or 1/2. The extension towards Horndeski
gravity shows no qualitative surprises, and $\gamma_{\scriptscriptstyle
\Sigma}$ is a constant in this context (only assuming that the Horndeski
potentials can be approximated by analytical functions). This implies that a
precise study on the bending of light for different impact parameters can in
principle be used to rule out the complete Horndeski action as an action for
gravity. Also, we comment on the consequences for $\gamma$ inferences at
external galaxies.
|
[
{
"created": "Tue, 22 Jun 2021 13:08:13 GMT",
"version": "v1"
},
{
"created": "Thu, 1 Jul 2021 16:42:15 GMT",
"version": "v2"
},
{
"created": "Mon, 9 Aug 2021 16:28:38 GMT",
"version": "v3"
}
] |
2021-08-10
|
[
[
"Toniato",
"Júnior D.",
""
],
[
"Rodrigues",
"Davi C.",
""
]
] |
We review the fundamentals and highlight the differences between some commonly used definitions for the PPN gamma parameter ($\gamma$) and the gravitational slip ($\eta$). Here we stress the usefulness of a gamma-like parameter used by Berry and Gair ($\gamma_{\scriptscriptstyle \Sigma}$) that parametrizes the bending of light and the Shapiro time delay in situations in which the standard $\gamma$ cannot be promptly used. First we apply our considerations to two well known cases, but for which some conflicting results can be found: massive Brans-Dicke gravity and $f(R)$ gravity (both the metric and the Palatini versions). Although the slip parameter is always well defined, it has in general no direct relation to either light deflection or the Shapiro time delay, hence care should be taken on imposing the PPN $\gamma$ bounds on the slip. We stress that, for any system with a well posed Newtonian limit, Palatini $f(R)$ theories always have $\gamma = 1$; while metric $f(R)$ theories can only have two values: either 1 or 1/2. The extension towards Horndeski gravity shows no qualitative surprises, and $\gamma_{\scriptscriptstyle \Sigma}$ is a constant in this context (only assuming that the Horndeski potentials can be approximated by analytical functions). This implies that a precise study on the bending of light for different impact parameters can in principle be used to rule out the complete Horndeski action as an action for gravity. Also, we comment on the consequences for $\gamma$ inferences at external galaxies.
|
gr-qc/9506046
| null |
Giampiero Esposito
|
The Impact of Quantum Cosmology on Quantum Field Theory
|
14 pages, plain TEX, to appear in Proceedings of the Moscow Quantum
Gravity Seminar, Moscow, June 12 - June 19, 1995
| null | null |
DSF preprint 95/27
|
gr-qc
| null |
The basic problem of quantum cosmology is the definition of the quantum state
of the universe, with appropriate boundary conditions on Riemannian
three-geometries. This paper describes recent progress in the corresponding
analysis of quantum amplitudes for Euclidean Maxwell theory and linearized
gravity. Within the framework of Faddeev-Popov formalism and zeta-function
regularization, various choices of mixed boundary conditions lead to a deeper
understanding of quantized gauge fields and quantum gravity in the presence of
boundaries.
|
[
{
"created": "Thu, 22 Jun 1995 14:56:07 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Esposito",
"Giampiero",
""
]
] |
The basic problem of quantum cosmology is the definition of the quantum state of the universe, with appropriate boundary conditions on Riemannian three-geometries. This paper describes recent progress in the corresponding analysis of quantum amplitudes for Euclidean Maxwell theory and linearized gravity. Within the framework of Faddeev-Popov formalism and zeta-function regularization, various choices of mixed boundary conditions lead to a deeper understanding of quantized gauge fields and quantum gravity in the presence of boundaries.
|
2309.06897
|
Mikhail Smolyakov
|
Vadim Egorov, Mikhail Smolyakov, Igor Volobuev
|
Quantization of spinor field in the Schwarzschild spacetime and spin
sums for solutions of the Dirac equation
|
20 pages, 2 figures. v2: minor revision of the text, figure added,
references added
|
Class. Quantum Grav. 41, 045002 (2024)
|
10.1088/1361-6382/ad1b8f
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We discuss the problem of canonical quantization of a free massive spinor
field in the Schwarzschild spacetime. It is shown that a consistent procedure
of canonical quantization of the field can be carried out without taking into
account the internal region of the black hole, the canonical commutation
relations in the resulting theory hold exactly and the Hamiltonian has the
standard form. Spin sums are obtained for solutions of the Dirac equation in
the Schwarzschild spacetime.
|
[
{
"created": "Wed, 13 Sep 2023 11:45:50 GMT",
"version": "v1"
},
{
"created": "Sun, 21 Jan 2024 13:13:01 GMT",
"version": "v2"
}
] |
2024-01-23
|
[
[
"Egorov",
"Vadim",
""
],
[
"Smolyakov",
"Mikhail",
""
],
[
"Volobuev",
"Igor",
""
]
] |
We discuss the problem of canonical quantization of a free massive spinor field in the Schwarzschild spacetime. It is shown that a consistent procedure of canonical quantization of the field can be carried out without taking into account the internal region of the black hole, the canonical commutation relations in the resulting theory hold exactly and the Hamiltonian has the standard form. Spin sums are obtained for solutions of the Dirac equation in the Schwarzschild spacetime.
|
0712.1030
|
Richard Umstaetter
|
R. Umstaetter, M. Tinto
|
Bayesian comparison of Post-Newtonian approximations of gravitational
wave chirp signals
|
37 pages, 9 figures
|
Phys.Rev.D77:082002,2008
|
10.1103/PhysRevD.77.082002
| null |
gr-qc
| null |
We estimate the probability of detecting a gravitational wave signal from
coalescing compact binaries in simulated data from a ground-based
interferometer detector of gravitational radiation using Bayesian model
selection. The simulated waveform of the chirp signal is assumed to be a
spin-less Post-Newtonian (PN) waveform of a given expansion order, while the
searching template is assumed to be either of the same Post-Newtonian family as
the simulated signal or one level below its Post-Newtonian expansion order.
Within the Bayesian framework, and by applying a reversible jump Markov chain
Monte Carlo simulation algorithm, we compare PN1.5 vs. PN2.0 and PN3.0 vs.
PN3.5 wave forms by deriving the detection probabilities, the statistical
uncertainties due to noise as a function of the SNR, and the posterior
distributions of the parameters. Our analysis indicates that the detection
probabilities are not compromised when simplified models are used for the
comparison, while the accuracies in the determination of the parameters
characterizing these signals can be significantly worsened, no matter what the
considered Post-Newtonian order expansion comparison is.
|
[
{
"created": "Thu, 6 Dec 2007 20:10:47 GMT",
"version": "v1"
},
{
"created": "Fri, 7 Dec 2007 19:55:20 GMT",
"version": "v2"
},
{
"created": "Tue, 11 Dec 2007 19:00:53 GMT",
"version": "v3"
}
] |
2008-11-26
|
[
[
"Umstaetter",
"R.",
""
],
[
"Tinto",
"M.",
""
]
] |
We estimate the probability of detecting a gravitational wave signal from coalescing compact binaries in simulated data from a ground-based interferometer detector of gravitational radiation using Bayesian model selection. The simulated waveform of the chirp signal is assumed to be a spin-less Post-Newtonian (PN) waveform of a given expansion order, while the searching template is assumed to be either of the same Post-Newtonian family as the simulated signal or one level below its Post-Newtonian expansion order. Within the Bayesian framework, and by applying a reversible jump Markov chain Monte Carlo simulation algorithm, we compare PN1.5 vs. PN2.0 and PN3.0 vs. PN3.5 wave forms by deriving the detection probabilities, the statistical uncertainties due to noise as a function of the SNR, and the posterior distributions of the parameters. Our analysis indicates that the detection probabilities are not compromised when simplified models are used for the comparison, while the accuracies in the determination of the parameters characterizing these signals can be significantly worsened, no matter what the considered Post-Newtonian order expansion comparison is.
|
1406.5111
|
Eric Poisson
|
Peter Zimmerman and Eric Poisson
|
Gravitational self-force in nonvacuum spacetimes
|
20 pages, no figures
| null |
10.1103/PhysRevD.90.084030
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The gravitational self-force has thus far been formulated in background
spacetimes for which the metric is a solution to the Einstein field equations
in vacuum. While this formulation is sufficient to describe the motion of a
small object around a black hole, other applications require a more general
formulation that allows for a nonvacuum background spacetime. We provide a
foundation for such extensions, and carry out a concrete formulation of the
gravitational self-force in two specific cases. In the first we consider a
particle of mass $m$ and scalar charge $q$ moving in a background spacetime
that contains a background scalar field. In the second we consider a particle
of mass $m$ and electric charge $e$ moving in an electrovac spacetime. The
self-force incorporates all couplings between the gravitational perturbations
and those of the scalar or electromagnetic fields. It is expressed as a sum of
local terms involving tensors defined in the background spacetime and evaluated
at the current position of the particle, as well as tail integrals that depend
on the past history of the particle. Because such an expression is rarely a
useful starting point for an explicit evaluation of the self-force, we also
provide covariant expressions for the singular potentials, expressed as local
expansions near the world line; these can be involved in the construction of
effective extended sources for the regular potentials, or in the computation of
regularization parameters when the self-force is computed as a sum over
spherical-harmonic modes.
|
[
{
"created": "Thu, 19 Jun 2014 17:00:04 GMT",
"version": "v1"
}
] |
2015-06-22
|
[
[
"Zimmerman",
"Peter",
""
],
[
"Poisson",
"Eric",
""
]
] |
The gravitational self-force has thus far been formulated in background spacetimes for which the metric is a solution to the Einstein field equations in vacuum. While this formulation is sufficient to describe the motion of a small object around a black hole, other applications require a more general formulation that allows for a nonvacuum background spacetime. We provide a foundation for such extensions, and carry out a concrete formulation of the gravitational self-force in two specific cases. In the first we consider a particle of mass $m$ and scalar charge $q$ moving in a background spacetime that contains a background scalar field. In the second we consider a particle of mass $m$ and electric charge $e$ moving in an electrovac spacetime. The self-force incorporates all couplings between the gravitational perturbations and those of the scalar or electromagnetic fields. It is expressed as a sum of local terms involving tensors defined in the background spacetime and evaluated at the current position of the particle, as well as tail integrals that depend on the past history of the particle. Because such an expression is rarely a useful starting point for an explicit evaluation of the self-force, we also provide covariant expressions for the singular potentials, expressed as local expansions near the world line; these can be involved in the construction of effective extended sources for the regular potentials, or in the computation of regularization parameters when the self-force is computed as a sum over spherical-harmonic modes.
|
gr-qc/0011064
|
Alexander Unzicker
|
Alexander Unzicker
|
What can Physics learn from Continuum Mechanics ?
|
19 pages, LaTeX, 8 figures
| null | null | null |
gr-qc cond-mat.mtrl-sci hep-th
| null |
This paper is mostly a collection of ideas already published by various
authors, some of them even a long time ago. Its intention is to bring the
reader to know some rather unknown papers of different fields that merit
interest and to show some relations between them the author claims to have
observed. In the first section, some comments on old unresolved problems in
theoretical physics are collected. In the following, I shall explain what
relation exists between Feynman graphs and the teleparallel theory of Einstein
and Cartan in the late 1920s, and the relation of both to the theories of the
incompressible aether around 1840. Reviewing these developments, we will have a
look at the continuum theory of dislocations developed by Kroener in the 1950s
and some techniques of differential geometry and topology relevant for a modern
description of defects in continous media. I will then illustrate some basic
concepts of nonlinear continuum mechanics and discuss applications to the above
theories. By doing so, I hope to attract attention to the possible relevance of
these facts for `fundamental' physics.
|
[
{
"created": "Mon, 20 Nov 2000 21:36:05 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Unzicker",
"Alexander",
""
]
] |
This paper is mostly a collection of ideas already published by various authors, some of them even a long time ago. Its intention is to bring the reader to know some rather unknown papers of different fields that merit interest and to show some relations between them the author claims to have observed. In the first section, some comments on old unresolved problems in theoretical physics are collected. In the following, I shall explain what relation exists between Feynman graphs and the teleparallel theory of Einstein and Cartan in the late 1920s, and the relation of both to the theories of the incompressible aether around 1840. Reviewing these developments, we will have a look at the continuum theory of dislocations developed by Kroener in the 1950s and some techniques of differential geometry and topology relevant for a modern description of defects in continous media. I will then illustrate some basic concepts of nonlinear continuum mechanics and discuss applications to the above theories. By doing so, I hope to attract attention to the possible relevance of these facts for `fundamental' physics.
|
gr-qc/0702101
|
Catherine Williams
|
Catherine Williams
|
Asymptotic Behavior of Spherically Symmetric Marginally Trapped Tubes
|
43 pages, 7 figures. Updated to agree with published version; Theorem
1 strengthened slightly, minor issues fixed
|
AnnalesHenriPoincare9:1029-1067,2008
|
10.1007/s00023-008-0385-5
| null |
gr-qc math.DG
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We give conditions on a general stress-energy tensor T_{\alpha \beta} in a
spherically symmetric black hole spacetime which are sufficient to guarantee
that the black hole will contain a (spherically symmetric) marginally trapped
tube which is eventually achronal, connected, and asymptotic to the event
horizon. Price law decay per se is not required for this asymptotic result, and
in this general setting, such decay only implies that the marginally trapped
tube has finite length with respect to the induced metric. We do, however,
impose a smallness condition (B1) which one may obtain in practice by imposing
decay on the T_{vv} component of the stress-energy tensor. We give two
applications of the theorem to self-gravitating Higgs field spacetimes, one
using weak Price law decay, the other certain strong smallness and monotonicity
assumptions.
|
[
{
"created": "Mon, 19 Feb 2007 07:49:12 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Aug 2007 22:05:40 GMT",
"version": "v2"
},
{
"created": "Wed, 14 Jan 2009 03:42:26 GMT",
"version": "v3"
}
] |
2009-01-14
|
[
[
"Williams",
"Catherine",
""
]
] |
We give conditions on a general stress-energy tensor T_{\alpha \beta} in a spherically symmetric black hole spacetime which are sufficient to guarantee that the black hole will contain a (spherically symmetric) marginally trapped tube which is eventually achronal, connected, and asymptotic to the event horizon. Price law decay per se is not required for this asymptotic result, and in this general setting, such decay only implies that the marginally trapped tube has finite length with respect to the induced metric. We do, however, impose a smallness condition (B1) which one may obtain in practice by imposing decay on the T_{vv} component of the stress-energy tensor. We give two applications of the theorem to self-gravitating Higgs field spacetimes, one using weak Price law decay, the other certain strong smallness and monotonicity assumptions.
|
gr-qc/9801061
|
Inyong Cho
|
Inyong Cho and Jemal Guven
|
Modelling the dynamics of global monopoles
|
44 pages, REVTeX, 11 PostScript figures, submitted to the Physical
Review D. Abstract's corrected
|
Phys.Rev. D58 (1998) 063502
|
10.1103/PhysRevD.58.063502
| null |
gr-qc astro-ph
| null |
A thin wall approximation is exploited to describe a global monopole coupled
to gravity. The core is modelled by de Sitter space; its boundary by a thin
wall with a constant energy density; its exterior by the asymptotic
Schwarzschild solution with negative gravitational mass $M$ and solid angle
deficit, $\Delta\Omega/4\pi = 8\pi G\eta^2$, where $\eta$ is the symmetry
breaking scale. The deficit angle equals $4\pi$ when $\eta=1/\sqrt{8\pi G}
\equiv M_p$. We find that: (1) if $\eta <M_p$, there exists a unique globally
static non-singular solution with a well defined mass, $M_0<0$. $M_0$ provides
a lower bound on $M$. If $M_0<M<0$, the solution oscillates. There are no
inflating solutions in this symmetry breaking regime. (2) if $\eta \ge M_p$,
non-singular solutions with an inflating core and an asymptotically
cosmological exterior will exist for all $M<0$. (3) if $\eta$ is not too large,
there exists a finite range of values of $M$ where a non-inflating monopole
will also exist. These solutions appear to be metastable towards inflation. If
$M$ is positive all solutions are singular. We provide a detailed description
of the configuration space of the model for each point in the space of
parameters, $(\eta, M)$ and trace the wall trajectories on both the interior
and the exterior spacetimes. Our results support the proposal that topological
defects can undergo inflation.
|
[
{
"created": "Mon, 19 Jan 1998 02:31:30 GMT",
"version": "v1"
},
{
"created": "Tue, 20 Jan 1998 09:17:59 GMT",
"version": "v2"
}
] |
2009-10-31
|
[
[
"Cho",
"Inyong",
""
],
[
"Guven",
"Jemal",
""
]
] |
A thin wall approximation is exploited to describe a global monopole coupled to gravity. The core is modelled by de Sitter space; its boundary by a thin wall with a constant energy density; its exterior by the asymptotic Schwarzschild solution with negative gravitational mass $M$ and solid angle deficit, $\Delta\Omega/4\pi = 8\pi G\eta^2$, where $\eta$ is the symmetry breaking scale. The deficit angle equals $4\pi$ when $\eta=1/\sqrt{8\pi G} \equiv M_p$. We find that: (1) if $\eta <M_p$, there exists a unique globally static non-singular solution with a well defined mass, $M_0<0$. $M_0$ provides a lower bound on $M$. If $M_0<M<0$, the solution oscillates. There are no inflating solutions in this symmetry breaking regime. (2) if $\eta \ge M_p$, non-singular solutions with an inflating core and an asymptotically cosmological exterior will exist for all $M<0$. (3) if $\eta$ is not too large, there exists a finite range of values of $M$ where a non-inflating monopole will also exist. These solutions appear to be metastable towards inflation. If $M$ is positive all solutions are singular. We provide a detailed description of the configuration space of the model for each point in the space of parameters, $(\eta, M)$ and trace the wall trajectories on both the interior and the exterior spacetimes. Our results support the proposal that topological defects can undergo inflation.
|
2303.08948
|
Peter K.F. Kuhfittig
|
Peter K.F. Kuhfittig
|
Dark-energy wormholes in generalized Kaluza-Klein gravity
|
11 pages, no figures
|
Journal of the Korean Physical Society, vol 84, pp. 497-503, 2024
| null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
This paper discusses traversable wormholes in a dark-energy setting by
starting with a model due to Sung-Won Kim. This model, based on the
Friedmann-Lemaitre-Robertson-Walker model, is combined with a generalized
Kaluza-Klein model. It is well known that phantom dark energy can in principle
support traversable wormholes due to the violation of the null energy condition
(NEC), a necessary condition for holding a wormhole open. Since the phantom
divide constitutes a serious barrier, we retain the dark-energy assumption
$a''(t)>0$ but stay below the phantom divide. To show that the violation of the
NEC can only come from the fifth dimension requires a careful analysis of the
scale factor $a(t)$. While needed in the overall model, certain 1-forms lack
this scale factor since the extra dimension, often assumed to be compactified,
would not be affected by the cosmological expansion. The result is a viable
wormhole model of the Sung-Won Kim type. Our main conclusion involves
Morris-Thorne wormholes: due to the Kaluza-Klein gravity, we obtain a complete
wormhole solution without crossing the phantom divide.
|
[
{
"created": "Wed, 15 Mar 2023 21:38:15 GMT",
"version": "v1"
},
{
"created": "Fri, 15 Dec 2023 23:54:24 GMT",
"version": "v2"
},
{
"created": "Thu, 28 Mar 2024 19:33:10 GMT",
"version": "v3"
}
] |
2024-04-01
|
[
[
"Kuhfittig",
"Peter K. F.",
""
]
] |
This paper discusses traversable wormholes in a dark-energy setting by starting with a model due to Sung-Won Kim. This model, based on the Friedmann-Lemaitre-Robertson-Walker model, is combined with a generalized Kaluza-Klein model. It is well known that phantom dark energy can in principle support traversable wormholes due to the violation of the null energy condition (NEC), a necessary condition for holding a wormhole open. Since the phantom divide constitutes a serious barrier, we retain the dark-energy assumption $a''(t)>0$ but stay below the phantom divide. To show that the violation of the NEC can only come from the fifth dimension requires a careful analysis of the scale factor $a(t)$. While needed in the overall model, certain 1-forms lack this scale factor since the extra dimension, often assumed to be compactified, would not be affected by the cosmological expansion. The result is a viable wormhole model of the Sung-Won Kim type. Our main conclusion involves Morris-Thorne wormholes: due to the Kaluza-Klein gravity, we obtain a complete wormhole solution without crossing the phantom divide.
|
2102.05465
|
Genly Le\'on
|
Genly Leon, Esteban Gonz\'alez, Samuel Lepe, Claudio Michea, and
Alfredo D. Millano
|
Averaging Generalized Scalar Field Cosmologies I: Locally Rotationally
Symmetric Bianchi III and open Friedmann-Lema\^itre-Robertson-Walker models
|
Research Program Averaging Generalized Scalar Field Cosmologies, part
I. 48 pages, 24 compound figures. Minor revision. References added
| null |
10.1140/epjc/s10052-021-09185-7
| null |
gr-qc math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Scalar field cosmologies with a generalized harmonic potential and a matter
fluid with a barotropic Equation of State (EoS) with barotropic index $\gamma$
for Locally Rotationally Symmetric (LRS) Bianchi III metric and open
Friedmann-Lema\^itre-Robertson-Walker (FLRW) metric are investigated. Methods
from the theory of averaging of nonlinear dynamical systems are used to prove
that time-dependent systems and their corresponding time-averaged versions have
the same late-time dynamics. Therefore, simple time-averaged systems determine
the future asymptotic behavior. Depending on values of barotropic index
$\gamma$ late-time attractors of physical interests for LRS Bianchi III metric
are Bianchi III flat spacetime, matter dominated FLRW universe (mimicking de
Sitter, quintessence or zero acceleration solutions) and matter-curvature
scaling solution. For open FLRW metric late-time attractors are a matter
dominated FLRW universe and Milne solution. With this approach, oscillations
entering nonlinear system through Klein-Gordon (KG) equation can be controlled
and smoothed out as the Hubble factor $H$ - acting as a time-dependent
perturbation parameter - tends monotonically to zero. Numerical simulations are
presented as evidence of such behaviour.
|
[
{
"created": "Wed, 10 Feb 2021 14:41:30 GMT",
"version": "v1"
},
{
"created": "Thu, 11 Feb 2021 21:48:14 GMT",
"version": "v2"
},
{
"created": "Tue, 30 Mar 2021 17:29:38 GMT",
"version": "v3"
},
{
"created": "Fri, 23 Apr 2021 00:58:41 GMT",
"version": "v4"
}
] |
2021-06-03
|
[
[
"Leon",
"Genly",
""
],
[
"González",
"Esteban",
""
],
[
"Lepe",
"Samuel",
""
],
[
"Michea",
"Claudio",
""
],
[
"Millano",
"Alfredo D.",
""
]
] |
Scalar field cosmologies with a generalized harmonic potential and a matter fluid with a barotropic Equation of State (EoS) with barotropic index $\gamma$ for Locally Rotationally Symmetric (LRS) Bianchi III metric and open Friedmann-Lema\^itre-Robertson-Walker (FLRW) metric are investigated. Methods from the theory of averaging of nonlinear dynamical systems are used to prove that time-dependent systems and their corresponding time-averaged versions have the same late-time dynamics. Therefore, simple time-averaged systems determine the future asymptotic behavior. Depending on values of barotropic index $\gamma$ late-time attractors of physical interests for LRS Bianchi III metric are Bianchi III flat spacetime, matter dominated FLRW universe (mimicking de Sitter, quintessence or zero acceleration solutions) and matter-curvature scaling solution. For open FLRW metric late-time attractors are a matter dominated FLRW universe and Milne solution. With this approach, oscillations entering nonlinear system through Klein-Gordon (KG) equation can be controlled and smoothed out as the Hubble factor $H$ - acting as a time-dependent perturbation parameter - tends monotonically to zero. Numerical simulations are presented as evidence of such behaviour.
|
1409.4314
|
Georgios Lukes Gerakopoulos
|
Georgios Lukes-Gerakopoulos, Jonathan Seyrich, Daniela Kunst
|
Investigating spinning test particles: spin supplementary conditions and
the Hamiltonian formalism
|
17 pages, 11 figures, accepted for publication in PRD
| null |
10.1103/PhysRevD.90.104019
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper we report the results of a thorough numerical study of the
motion of spinning particles in Kerr spacetime with different prescriptions. We
first evaluate the Mathisson-Papapetrou equations with two different spin
supplementary conditions, namely, the Tulczyjew and the Newton-Wigner, and make
a comparison of these two cases. We then use the Hamiltonian formalism given by
Barausse, Racine, and Buonanno in [Phys. Rev. D, 80, 104025 (2009)] to evolve
the orbits and compare them with the corresponding orbits provided by the
Mathisson-Papapetrou equations. We include a full description of how to treat
the issues arising in the numerical implementation.
|
[
{
"created": "Mon, 15 Sep 2014 16:35:31 GMT",
"version": "v1"
},
{
"created": "Tue, 4 Nov 2014 11:02:35 GMT",
"version": "v2"
}
] |
2014-11-19
|
[
[
"Lukes-Gerakopoulos",
"Georgios",
""
],
[
"Seyrich",
"Jonathan",
""
],
[
"Kunst",
"Daniela",
""
]
] |
In this paper we report the results of a thorough numerical study of the motion of spinning particles in Kerr spacetime with different prescriptions. We first evaluate the Mathisson-Papapetrou equations with two different spin supplementary conditions, namely, the Tulczyjew and the Newton-Wigner, and make a comparison of these two cases. We then use the Hamiltonian formalism given by Barausse, Racine, and Buonanno in [Phys. Rev. D, 80, 104025 (2009)] to evolve the orbits and compare them with the corresponding orbits provided by the Mathisson-Papapetrou equations. We include a full description of how to treat the issues arising in the numerical implementation.
|
gr-qc/9803011
|
Don Marolf
|
Donald Marolf
|
Summary of GR15 Session D1(1), Quantum General Relativity
|
4 pages ReVTeX, reference corrected
| null | null |
SU-GP-98/3-1
|
gr-qc
| null |
This summary was prepared for the proceedings of the GR15 conference in Pune,
India in Dec. 1997.
|
[
{
"created": "Mon, 2 Mar 1998 14:32:57 GMT",
"version": "v1"
},
{
"created": "Tue, 3 Mar 1998 21:20:09 GMT",
"version": "v2"
},
{
"created": "Thu, 5 Mar 1998 16:41:11 GMT",
"version": "v3"
}
] |
2007-05-23
|
[
[
"Marolf",
"Donald",
""
]
] |
This summary was prepared for the proceedings of the GR15 conference in Pune, India in Dec. 1997.
|
gr-qc/0205024
|
Roberto Colistete Junior
|
R. Colistete, Jr.
|
Constraints on Non-Singular Cosmological Models with Quadratic
Lagrangians
|
11 pages, RevTeX, 3 Postscript figures
| null |
10.1142/9789812777386_0147
| null |
gr-qc
| null |
We consider the generalized set of theories of gravitation whose Lagrangians
contain the term $R^{2}$ : $L=\sqrt{-g}(R+\beta R^{2})$. Inserting the RW
metric with an imposed non-singular and inflationary behaviour of the scale
factor $a(t)$, and using a arbitrary perfect fluid, we study the properties of
$\rho $ and $p$ in this context. By requiring the positivity of the energy
density, as well as real and finite velocity of sound, we can obtain the range
of values of $\beta $ that ensure the inflationary behaviour and absence of
singularity.
|
[
{
"created": "Tue, 7 May 2002 10:05:32 GMT",
"version": "v1"
}
] |
2017-08-23
|
[
[
"Colistete,",
"R.",
"Jr."
]
] |
We consider the generalized set of theories of gravitation whose Lagrangians contain the term $R^{2}$ : $L=\sqrt{-g}(R+\beta R^{2})$. Inserting the RW metric with an imposed non-singular and inflationary behaviour of the scale factor $a(t)$, and using a arbitrary perfect fluid, we study the properties of $\rho $ and $p$ in this context. By requiring the positivity of the energy density, as well as real and finite velocity of sound, we can obtain the range of values of $\beta $ that ensure the inflationary behaviour and absence of singularity.
|
gr-qc/9712087
|
David Yetter
|
L. Crane and D.N. Yetter (Kansas State Univ.)
|
On the Classical Limit of the Balanced State Sum
|
6 pages LaTex, 2 figures in PostScript
| null | null | null |
gr-qc
| null |
The purpose of this note is to make several advances in the interpretation of
the balanced state sum model by Barrett and Crane in gr-qc/9709028 as a quantum
theory of gravity. First, we outline a shortcoming of the definition of the
model in pointed out to us by Barrett and Baez in private communication, and
explain how to correct it. Second, we show that the classical limit of our
state sum reproduces the Einstein-Hilbert lagrangian whenever the term in the
state sum to which it is applied has a geometrical interpretation. Next we
outline a program to demonstrate that the classical limit of the state sum is
in fact dominated by terms with geometrical meaning. This uses in an essential
way the alteration we have made to the model in order to fix the shortcoming
discussed in the first section. Finally, we make a brief discussion of the
Minkowski signature version of the model.
|
[
{
"created": "Mon, 22 Dec 1997 21:06:59 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Crane",
"L.",
"",
"Kansas State Univ."
],
[
"Yetter",
"D. N.",
"",
"Kansas State Univ."
]
] |
The purpose of this note is to make several advances in the interpretation of the balanced state sum model by Barrett and Crane in gr-qc/9709028 as a quantum theory of gravity. First, we outline a shortcoming of the definition of the model in pointed out to us by Barrett and Baez in private communication, and explain how to correct it. Second, we show that the classical limit of our state sum reproduces the Einstein-Hilbert lagrangian whenever the term in the state sum to which it is applied has a geometrical interpretation. Next we outline a program to demonstrate that the classical limit of the state sum is in fact dominated by terms with geometrical meaning. This uses in an essential way the alteration we have made to the model in order to fix the shortcoming discussed in the first section. Finally, we make a brief discussion of the Minkowski signature version of the model.
|
2303.02021
|
Jann Zosso
|
Lavinia Heisenberg and Nicol\'as Yunes and Jann Zosso
|
Gravitational wave memory beyond general relativity
|
39 pages
| null |
10.1103/PhysRevD.108.024010
| null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
Gravitational wave memory is a nonoscillatory correction to the gravitational
wave strain predicted by general relativity, which has yet to be detected.
Within general relativity, its dominant component, known as the null memory,
can be understood as arising from the backreaction of the energy carried by
gravitational waves, and therefore it corresponds to a direct manifestation of
the nonlinearity of the theory. In this paper, we investigate the null-memory
prediction in a broad class of modified gravity theories, with the aim of
exploring potential lessons to be learned from future measurements of the
memory effect. Based on Isaacson's approach to the leading-order field
equations, we in particular compute the null memory for the most general
scalar-vector-tensor theory with second-order equations of motion and vanishing
field potentials. We find that the functional form of the null memory is only
modified through the potential presence of additional radiative null energy
sources in the theory. We subsequently generalize this result by proving a
theorem that states that the simple structure of the tensor null-memory
equation remains unaltered in any metric theory whose massless gravitational
fields satisfy decoupled wave equations to first order in perturbation theory,
which encompasses a large class of viable extensions to general relativity.
|
[
{
"created": "Fri, 3 Mar 2023 15:40:36 GMT",
"version": "v1"
},
{
"created": "Mon, 24 Jul 2023 20:27:02 GMT",
"version": "v2"
}
] |
2023-07-26
|
[
[
"Heisenberg",
"Lavinia",
""
],
[
"Yunes",
"Nicolás",
""
],
[
"Zosso",
"Jann",
""
]
] |
Gravitational wave memory is a nonoscillatory correction to the gravitational wave strain predicted by general relativity, which has yet to be detected. Within general relativity, its dominant component, known as the null memory, can be understood as arising from the backreaction of the energy carried by gravitational waves, and therefore it corresponds to a direct manifestation of the nonlinearity of the theory. In this paper, we investigate the null-memory prediction in a broad class of modified gravity theories, with the aim of exploring potential lessons to be learned from future measurements of the memory effect. Based on Isaacson's approach to the leading-order field equations, we in particular compute the null memory for the most general scalar-vector-tensor theory with second-order equations of motion and vanishing field potentials. We find that the functional form of the null memory is only modified through the potential presence of additional radiative null energy sources in the theory. We subsequently generalize this result by proving a theorem that states that the simple structure of the tensor null-memory equation remains unaltered in any metric theory whose massless gravitational fields satisfy decoupled wave equations to first order in perturbation theory, which encompasses a large class of viable extensions to general relativity.
|
gr-qc/9510067
| null |
Marco Litterio, Leszek M. Soko{\l}owski, Zdzis{\l}aw A. Golda, Luca
Amendola and Andrzej Dyrek
|
Anisotropic Inflation from Extra Dimensions
|
LaTeX, 11 pages, 5 figures available via fax on request to
litterio@astrom.astro.it, submitted to Phys. Lett. B
|
Phys.Lett. B382 (1996) 45-52
|
10.1016/0370-2693(96)00361-9
| null |
gr-qc
| null |
Vacuum multidimensional cosmological models with internal spaces being
compact $n$-dimensional Lie group manifolds are considered. Products of
3-spheres and $SU(3)$ manifold (a novelty in cosmology) are studied. It turns
out that the dynamical evolution of the internal space drives an accelerated
expansion of the external world (power law inflation). This generic solution
(attractor in a phase space) is determined by the Lie group space without any
fine tuning or arbitrary inflaton potentials. Matter in the four dimensions
appears in the form of a number of scalar fields representing anisotropic scale
factors for the internal space. Along the attractor solution the volume of the
internal space grows logarithmically in time. This simple and natural model
should be completed by mechanisms terminating the inflationary evolution and
transforming the geometric scalar fields into ordinary particles.
|
[
{
"created": "Tue, 31 Oct 1995 16:25:07 GMT",
"version": "v1"
}
] |
2009-10-28
|
[
[
"Litterio",
"Marco",
""
],
[
"Sokołowski",
"Leszek M.",
""
],
[
"Golda",
"Zdzisław A.",
""
],
[
"Amendola",
"Luca",
""
],
[
"Dyrek",
"Andrzej",
""
]
] |
Vacuum multidimensional cosmological models with internal spaces being compact $n$-dimensional Lie group manifolds are considered. Products of 3-spheres and $SU(3)$ manifold (a novelty in cosmology) are studied. It turns out that the dynamical evolution of the internal space drives an accelerated expansion of the external world (power law inflation). This generic solution (attractor in a phase space) is determined by the Lie group space without any fine tuning or arbitrary inflaton potentials. Matter in the four dimensions appears in the form of a number of scalar fields representing anisotropic scale factors for the internal space. Along the attractor solution the volume of the internal space grows logarithmically in time. This simple and natural model should be completed by mechanisms terminating the inflationary evolution and transforming the geometric scalar fields into ordinary particles.
|
0902.1857
|
Farhad Darabi
|
F. Darabi
|
Modified gravity and Space-Time-Matter theory
|
10 pages, contribution to the anniversary volume "The Problems of
Modern Cosmology", on the occasion of the 50th birthday of Prof. S. D.
Odintsov. Editor: Prof. P. M. Lavrov, Tomsk State Pedagogical University
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The correspondence between $f(R)$ theories of gravity and model theories
explaining induced dark energy in a 5D Ricci-flat universe, known as the
Space-Time-Matter theory (STM), is studied. It is shown that such
correspondence may be used to interpret the four dimensional expressions,
induced from geometry in 5D STM theories, in terms of the extra terms appearing
in $f(R)$ theories of gravity. The method is demonstrated by providing an
explicit example in which a given $f(R)$ is used to predict the properties of
the corresponding 5D Ricci-flat universe. The accelerated expansion and the
induced dark energy in a 5D Ricci-flat universe characterized by a big bounce
is studied and it is shown that an arbitrary function $\mu(t)$ in the 5D
solutions can be rewritten, in terms of the redshift $z$, as a new arbitrary
function $F(z)$ which corresponds to the 4D curvature quintessence models.
|
[
{
"created": "Wed, 11 Feb 2009 11:41:05 GMT",
"version": "v1"
}
] |
2009-02-12
|
[
[
"Darabi",
"F.",
""
]
] |
The correspondence between $f(R)$ theories of gravity and model theories explaining induced dark energy in a 5D Ricci-flat universe, known as the Space-Time-Matter theory (STM), is studied. It is shown that such correspondence may be used to interpret the four dimensional expressions, induced from geometry in 5D STM theories, in terms of the extra terms appearing in $f(R)$ theories of gravity. The method is demonstrated by providing an explicit example in which a given $f(R)$ is used to predict the properties of the corresponding 5D Ricci-flat universe. The accelerated expansion and the induced dark energy in a 5D Ricci-flat universe characterized by a big bounce is studied and it is shown that an arbitrary function $\mu(t)$ in the 5D solutions can be rewritten, in terms of the redshift $z$, as a new arbitrary function $F(z)$ which corresponds to the 4D curvature quintessence models.
|
2106.08653
|
Bin Wu
|
Duo Li, Bin Wu, Zhen-Ming Xu and Wen-Li Yang
|
A shell of Bosons in Spherically Symmetric spacetimes
|
16 pages;v2:published version
|
Phys.Lett.B 820(2021) 136588
|
10.1016/j.physletb.2021.136588
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The thermodynamic properties of a shell of bosons with the inner surface
locating at Planck length away from the horizon of Schwarzschild black holes by
using statistical mechanics are studied. The covariant partition function of
bosons is obtained, from which the Bose-Einstein condensation of bosons is
found at a non-zero temperature in the curved spacetimes. As a special case of
bosons, we analyze the entropy of photon gas near the horizon of the
Schwarzschild black hole, which shows an area dependence similar to the
Bekenstein-Hawking entropy. The results may offer new perspectives on the study
of black hole thermodynamics. All these are extended to the $D+1$ dimensional
spherically symmetric static spacetimes.
|
[
{
"created": "Wed, 16 Jun 2021 09:32:06 GMT",
"version": "v1"
},
{
"created": "Sun, 29 Aug 2021 03:56:40 GMT",
"version": "v2"
}
] |
2021-08-31
|
[
[
"Li",
"Duo",
""
],
[
"Wu",
"Bin",
""
],
[
"Xu",
"Zhen-Ming",
""
],
[
"Yang",
"Wen-Li",
""
]
] |
The thermodynamic properties of a shell of bosons with the inner surface locating at Planck length away from the horizon of Schwarzschild black holes by using statistical mechanics are studied. The covariant partition function of bosons is obtained, from which the Bose-Einstein condensation of bosons is found at a non-zero temperature in the curved spacetimes. As a special case of bosons, we analyze the entropy of photon gas near the horizon of the Schwarzschild black hole, which shows an area dependence similar to the Bekenstein-Hawking entropy. The results may offer new perspectives on the study of black hole thermodynamics. All these are extended to the $D+1$ dimensional spherically symmetric static spacetimes.
|
2008.08317
|
Javier Relancio
|
J.J. Relancio, S. Liberati
|
Constraints on the deformation scale of a geometry in the cotangent
bundle
|
11 pages
|
Phys. Rev. D 102, 104025 (2020)
|
10.1103/PhysRevD.102.104025
| null |
gr-qc hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
There are several studies proposing phenomenological consequences of a
deformation of special and general relativity. Here, we cast novel constraints
on the deformation parameter of a metric in the cotangent bundle accounting for
a curved momentum space. In an expanding universe, we study three possible
observations that could restrict our model, focusing on the deformations of
velocity, redshift and luminosity distance, which in the aforementioned
framework, depend on the energy of the particles. We find that for an energy
dependent velocity there would be no time delay for massless particles since
also the observed distance to the source depends on the energy. For the
redshift and luminosity distance we see that a scale of the order of some keV
could be compatible with our model. This shows that the constraints on the
high-energy scale parametrizing the momentum dependent deviation from a
Friedmann-Robertson-Walker metric are at the moment weak due to the fact that
the precision (rather than energies) needed in the observational constraints
are extremely high. However, this is not the case when considering the
synchrotron radiation. Indeed, the observation of such emission from the Crab
Nebula, for deformations leading to subluminal propagation at high energies,
leads to a constraint for the high-energy scale of the order of 1 PeV.
|
[
{
"created": "Wed, 19 Aug 2020 08:07:42 GMT",
"version": "v1"
}
] |
2020-11-18
|
[
[
"Relancio",
"J. J.",
""
],
[
"Liberati",
"S.",
""
]
] |
There are several studies proposing phenomenological consequences of a deformation of special and general relativity. Here, we cast novel constraints on the deformation parameter of a metric in the cotangent bundle accounting for a curved momentum space. In an expanding universe, we study three possible observations that could restrict our model, focusing on the deformations of velocity, redshift and luminosity distance, which in the aforementioned framework, depend on the energy of the particles. We find that for an energy dependent velocity there would be no time delay for massless particles since also the observed distance to the source depends on the energy. For the redshift and luminosity distance we see that a scale of the order of some keV could be compatible with our model. This shows that the constraints on the high-energy scale parametrizing the momentum dependent deviation from a Friedmann-Robertson-Walker metric are at the moment weak due to the fact that the precision (rather than energies) needed in the observational constraints are extremely high. However, this is not the case when considering the synchrotron radiation. Indeed, the observation of such emission from the Crab Nebula, for deformations leading to subluminal propagation at high energies, leads to a constraint for the high-energy scale of the order of 1 PeV.
|
gr-qc/0009060
|
Jorge Pullin
|
Jorge Pullin
|
Matters of Gravity, the newsletter of the APS Topical Group on
Gravitation
|
26 pages, LaTeX with epsf and html.sty, ISSN 1527-3431, Jorge Pullin
(editor), html, ps and pdf versions at http://gravity.phys.psu.edu/mog.html
| null | null |
MOG-16
|
gr-qc
| null |
Research Briefs:
Cosmic microwave background anisotropy experiments, by Sean Carroll
LISA Project Update by Bill Folkner
An update on the r-mode instability, by Nils Andersson
Laboratory experiments: news from MG9, by Riley Newman
Progress toward Commissioning the LIGO detectors, by Stan Whitcomb
160 Hours of Data Taken on TAMA300, by Seiji Kawamura
Conference reports:
Kipfest, by Richard Price
Third Capra meeting, by Eric Poisson
GR at the XIIIth Congress on Mathematical Physics, by Abhay Ashtekar
3rd International LISA Symposium, by Curt Cutler
|
[
{
"created": "Sun, 17 Sep 2000 21:38:08 GMT",
"version": "v1"
}
] |
2009-03-10
|
[
[
"Pullin",
"Jorge",
""
]
] |
Research Briefs: Cosmic microwave background anisotropy experiments, by Sean Carroll LISA Project Update by Bill Folkner An update on the r-mode instability, by Nils Andersson Laboratory experiments: news from MG9, by Riley Newman Progress toward Commissioning the LIGO detectors, by Stan Whitcomb 160 Hours of Data Taken on TAMA300, by Seiji Kawamura Conference reports: Kipfest, by Richard Price Third Capra meeting, by Eric Poisson GR at the XIIIth Congress on Mathematical Physics, by Abhay Ashtekar 3rd International LISA Symposium, by Curt Cutler
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.