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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
2204.05473 | Umananda Dev Goswami | Jyatsnasree Bora, Dhruba Jyoti Gogoi and Umananda Dev Goswami | Strange stars in $f(\mathcal{R})$ gravity Palatini formalism and
gravitational wave echoes from them | 22 pages, 9 figures | JCAP 09, 057 (2022) | 10.1088/1475-7516/2022/09/057 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The compact stars are promising candidates associated with the generation of
gravitational waves (GWs). In this work, we study a special type of compact
stars known as strange stars in the $f(\mathcal{R})$ gravity Palatini
formalism. Here we consider three promising $f(\mathcal{R})$ gravity models
viz., Starobinsky, Hu-Sawicki and Gogoi-Goswami models in the domain of MIT Bag
model and linear equations of state (EoSs). We compute the stellar structures
numerically and constrained the $f(\mathcal{R})$ model parameters with a set of
probable strange star candidates. The study shows that the consideration of
stiffer MIT Bag model and linear EoSs within a favourable set of
$f(\mathcal{R})$ gravity model parameters may result in strange stars with
sufficient compactness to produce echoes of GWs. Thus, we have computed the GWs
echo frequencies and characteristic echo times for such stars. It is found that
in compliance with the experimentally obtained possible strange star
candidates, the obtained GW echo frequencies for all the models are in the
range of $65 - 85$ kHz.
| [
{
"created": "Tue, 12 Apr 2022 01:51:05 GMT",
"version": "v1"
},
{
"created": "Thu, 22 Sep 2022 07:08:15 GMT",
"version": "v2"
}
] | 2022-09-23 | [
[
"Bora",
"Jyatsnasree",
""
],
[
"Gogoi",
"Dhruba Jyoti",
""
],
[
"Goswami",
"Umananda Dev",
""
]
] | The compact stars are promising candidates associated with the generation of gravitational waves (GWs). In this work, we study a special type of compact stars known as strange stars in the $f(\mathcal{R})$ gravity Palatini formalism. Here we consider three promising $f(\mathcal{R})$ gravity models viz., Starobinsky, Hu-Sawicki and Gogoi-Goswami models in the domain of MIT Bag model and linear equations of state (EoSs). We compute the stellar structures numerically and constrained the $f(\mathcal{R})$ model parameters with a set of probable strange star candidates. The study shows that the consideration of stiffer MIT Bag model and linear EoSs within a favourable set of $f(\mathcal{R})$ gravity model parameters may result in strange stars with sufficient compactness to produce echoes of GWs. Thus, we have computed the GWs echo frequencies and characteristic echo times for such stars. It is found that in compliance with the experimentally obtained possible strange star candidates, the obtained GW echo frequencies for all the models are in the range of $65 - 85$ kHz. |
1812.00314 | Huan-Hsin Tseng | Huan-Hsin Tseng | Gravitational Theories with Torsion | Doctoral Dissertation, National Tsing Hua University. 84 pages, 7
figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We give a complete formulation of Poincare gauge theory, starting from the
fibre bundle formulation to the resultant Riemann-Cartan spacetime. We also
introduce several diverse gravity theories descendent from the Poincare gauge
theory. Especially, the cosmological effect of the simple scalar-torsion (0^+)
mode in Poincare gauge theory of gravity is studied. In the theory, we treat
the geometric effect of torsion as an effective quantity, which behaves like
dark energy and study the effective equation of state (EoS) of the model.
We construct the extra dimension theory of teleparallel gravity by using
differential forms. In particular, we discuss the Kaluza-Klein and braneworld
scenarios by direct dimensional reduction and specifying the shape of fibre.
The FLRW cosmological scenario of the braneworld theory in teleparallel gravity
demonstrates its equivalence to general relativity (GR) in the field equations,
namely they possess the same Friedmann equation.
| [
{
"created": "Sun, 2 Dec 2018 03:25:27 GMT",
"version": "v1"
}
] | 2018-12-04 | [
[
"Tseng",
"Huan-Hsin",
""
]
] | We give a complete formulation of Poincare gauge theory, starting from the fibre bundle formulation to the resultant Riemann-Cartan spacetime. We also introduce several diverse gravity theories descendent from the Poincare gauge theory. Especially, the cosmological effect of the simple scalar-torsion (0^+) mode in Poincare gauge theory of gravity is studied. In the theory, we treat the geometric effect of torsion as an effective quantity, which behaves like dark energy and study the effective equation of state (EoS) of the model. We construct the extra dimension theory of teleparallel gravity by using differential forms. In particular, we discuss the Kaluza-Klein and braneworld scenarios by direct dimensional reduction and specifying the shape of fibre. The FLRW cosmological scenario of the braneworld theory in teleparallel gravity demonstrates its equivalence to general relativity (GR) in the field equations, namely they possess the same Friedmann equation. |
2101.09771 | Giampiero Esposito Dr. | Donato Bini, Giampiero Esposito | Investigating new forms of gravity-matter couplings in the gravitational
field equations | 3 figures, Revtex4 | Phys. Rev. D 103, 064030 (2021) | 10.1103/PhysRevD.103.064030 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper proposes a toy model where, in the Einstein equations, the
right-hand side is modified by the addition of a term proportional to the
symmetrized partial contraction of the Ricci tensor with the energy-momentum
tensor, while the left-hand side remains equal to the Einstein tensor. Bearing
in mind the existence of a natural length scale given by the Planck length,
dimensional analysis shows that such a term yields a correction linear in h to
the classical term, that is instead just proportional to the energy-momentum
tensor. One then obtains an effective energy-momentum tensor that consists of
three contributions: pure energy part, mechanical stress and thermal part. The
pure energy part has the appropriate property for dealing with the dark sector
of modern relativistic cosmology. Such a theory coincides with general
relativity in vacuum, and the resulting field equations are here solved for a
Dunn and Tupper metric, for departures from an interior Schwarzschild solution
as well as for a Friedmann-Lemaitre-Robertson-Walker universe.
| [
{
"created": "Sun, 24 Jan 2021 18:49:32 GMT",
"version": "v1"
}
] | 2021-03-24 | [
[
"Bini",
"Donato",
""
],
[
"Esposito",
"Giampiero",
""
]
] | This paper proposes a toy model where, in the Einstein equations, the right-hand side is modified by the addition of a term proportional to the symmetrized partial contraction of the Ricci tensor with the energy-momentum tensor, while the left-hand side remains equal to the Einstein tensor. Bearing in mind the existence of a natural length scale given by the Planck length, dimensional analysis shows that such a term yields a correction linear in h to the classical term, that is instead just proportional to the energy-momentum tensor. One then obtains an effective energy-momentum tensor that consists of three contributions: pure energy part, mechanical stress and thermal part. The pure energy part has the appropriate property for dealing with the dark sector of modern relativistic cosmology. Such a theory coincides with general relativity in vacuum, and the resulting field equations are here solved for a Dunn and Tupper metric, for departures from an interior Schwarzschild solution as well as for a Friedmann-Lemaitre-Robertson-Walker universe. |
0903.2290 | Gavin Polhemus | Gavin Polhemus, Andrew J. S. Hamilton, Colin S. Wallace | Entropy creation inside black holes points to observer complementarity | 13 pages. This is a companion paper to arXiv:0801.4415; Added
references | JHEP 0909:016,2009 | 10.1088/1126-6708/2009/09/016 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Heating processes inside large black holes can produce tremendous amounts of
entropy. Locality requires that this entropy adds on space-like surfaces, but
the resulting entropy (10^10 times the Bekenstein-Hawking entropy in an example
presented in the companion paper) exceeds the maximum entropy that can be
accommodated by the black hole's degrees of freedom. Observer complementarity,
which proposes a proliferation of non-local identifications inside the black
hole, allows the entropy to be accommodated as long as individual observers
inside the black hole see less than the Bekenstein-Hawking entropy. In the
specific model considered with huge entropy production, we show that individual
observers do see less than the Bekenstein-Hawking entropy, offering strong
support for observer complementarity.
| [
{
"created": "Thu, 12 Mar 2009 23:27:54 GMT",
"version": "v1"
},
{
"created": "Thu, 26 Mar 2009 22:22:48 GMT",
"version": "v2"
}
] | 2009-09-28 | [
[
"Polhemus",
"Gavin",
""
],
[
"Hamilton",
"Andrew J. S.",
""
],
[
"Wallace",
"Colin S.",
""
]
] | Heating processes inside large black holes can produce tremendous amounts of entropy. Locality requires that this entropy adds on space-like surfaces, but the resulting entropy (10^10 times the Bekenstein-Hawking entropy in an example presented in the companion paper) exceeds the maximum entropy that can be accommodated by the black hole's degrees of freedom. Observer complementarity, which proposes a proliferation of non-local identifications inside the black hole, allows the entropy to be accommodated as long as individual observers inside the black hole see less than the Bekenstein-Hawking entropy. In the specific model considered with huge entropy production, we show that individual observers do see less than the Bekenstein-Hawking entropy, offering strong support for observer complementarity. |
gr-qc/0604064 | Brandon Carter | Brandon Carter | Half century of black-hole theory: from physicists' purgatory to
mathematicians' paradise | 30 pages latex. Contrib. to Encuentros Relativistas Espanoles: A
Century of Relativity Theory, Oviedo, 2005 (ed. L. Mornas) | null | 10.1063/1.2218167 | null | gr-qc | null | Although implicit in the discovery of the Schwarzschild solution 40 years
earlier, the issues raised by the theory of what are now known as black holes
were so unsettling to physicists of Einstein's generation that the subject
remained in a state of semiclandestine gestation until his demise. That turning
point -- just half a century after Einstein's original foundation of relativity
theory, and just half a century ago today -- can be considered to mark the
birth of black hole theory as a subject of systematic development by physicists
of a new and less inhibited generation, whose enthusastic investigations have
revealed structures of unforeseen mathematical beauty, even though questions
about the physical significance of the concomitant singularities remain
controversial.
| [
{
"created": "Sat, 15 Apr 2006 10:34:56 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Carter",
"Brandon",
""
]
] | Although implicit in the discovery of the Schwarzschild solution 40 years earlier, the issues raised by the theory of what are now known as black holes were so unsettling to physicists of Einstein's generation that the subject remained in a state of semiclandestine gestation until his demise. That turning point -- just half a century after Einstein's original foundation of relativity theory, and just half a century ago today -- can be considered to mark the birth of black hole theory as a subject of systematic development by physicists of a new and less inhibited generation, whose enthusastic investigations have revealed structures of unforeseen mathematical beauty, even though questions about the physical significance of the concomitant singularities remain controversial. |
1507.03265 | Amare Abebe | Amare Abebe, Davood Momeni and Ratbay Myrzakulov | Shear-free Anisotropic Cosmological Models in f(R) Gravity | 18 pages, 4 figures, comments and references added to match accepted
version; to appear in General Relativity and Gravitation | Gen Relativ Gravit (2016) 48:49 | 10.1007/s10714-016-2046-1 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study a class of shear-free, homogeneous but anisotropic cosmological
models with imperfect matter sources in the context of f(R) gravity. We show
that the anisotropic stresses are related to the electric part of the Weyl
tensor in such a way that they balance each other. We also show that within the
class of orthogonal f(R) models, small perturbations of shear are damped, and
that the electric part of the Weyl tensor and the anisotropic stress tensor
decay with the expansion as well as the heat flux of the curvature fluid.
Specializing in locally rotationally symmetric spacetimes in orthonormal
frames, we examine the late-time behaviour of the de Sitter universe in $f(R)$
gravity. For the Starobinsky model of f(R), we study the evolutionary behavior
of the Universe by numerically integrating the Friedmann equation, where the
initial conditions for the expansion, acceleration and jerk parameters are
taken from observational data.
| [
{
"created": "Sun, 12 Jul 2015 20:10:12 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Mar 2016 22:29:49 GMT",
"version": "v2"
}
] | 2016-04-01 | [
[
"Abebe",
"Amare",
""
],
[
"Momeni",
"Davood",
""
],
[
"Myrzakulov",
"Ratbay",
""
]
] | We study a class of shear-free, homogeneous but anisotropic cosmological models with imperfect matter sources in the context of f(R) gravity. We show that the anisotropic stresses are related to the electric part of the Weyl tensor in such a way that they balance each other. We also show that within the class of orthogonal f(R) models, small perturbations of shear are damped, and that the electric part of the Weyl tensor and the anisotropic stress tensor decay with the expansion as well as the heat flux of the curvature fluid. Specializing in locally rotationally symmetric spacetimes in orthonormal frames, we examine the late-time behaviour of the de Sitter universe in $f(R)$ gravity. For the Starobinsky model of f(R), we study the evolutionary behavior of the Universe by numerically integrating the Friedmann equation, where the initial conditions for the expansion, acceleration and jerk parameters are taken from observational data. |
1707.02299 | Matthew Lippert | Steven L. Liebling, Michael Kavic, and Matthew Lippert | Probing Near-Horizon Fluctuations with Black Hole Binary Mergers | 7 pages, 6 figures; v2: published version | JHEP 1803 (2018) 176 | 10.1007/JHEP03(2018)176 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The strong version of the nonviolent nonlocality proposal of Giddings
predicts "strong but soft" quantum metric fluctuations near black hole horizons
in an attempt to resolve the information paradox. To study observable
signatures of this proposal, we numerically solve Einstein's equations modified
by these fluctuations and analyze the gravitational wave signal from the
inspiral and merger of two black holes. In a model of evolution for such
fluctuations, we show that they lead to significant deviations in the observed
waveform, even when the black holes are still well separated, and could
potentially be observed by aLIGO.
| [
{
"created": "Fri, 7 Jul 2017 18:00:00 GMT",
"version": "v1"
},
{
"created": "Tue, 3 Apr 2018 19:02:00 GMT",
"version": "v2"
}
] | 2020-05-20 | [
[
"Liebling",
"Steven L.",
""
],
[
"Kavic",
"Michael",
""
],
[
"Lippert",
"Matthew",
""
]
] | The strong version of the nonviolent nonlocality proposal of Giddings predicts "strong but soft" quantum metric fluctuations near black hole horizons in an attempt to resolve the information paradox. To study observable signatures of this proposal, we numerically solve Einstein's equations modified by these fluctuations and analyze the gravitational wave signal from the inspiral and merger of two black holes. In a model of evolution for such fluctuations, we show that they lead to significant deviations in the observed waveform, even when the black holes are still well separated, and could potentially be observed by aLIGO. |
gr-qc/0002077 | Richard Price | Zeferino Andrade and Richard H. Price | Shell sources as a probe of relativistic effects in neutron star models | 16 pages LaTeX with 6 eps figures; submitted to Phys. Rev. D | Phys.Rev. D62 (2000) 044032 | 10.1103/PhysRevD.62.044032 | null | gr-qc | null | A perturbing shell is introduced as a device for studying the excitation of
fluid motions in relativistic stellar models. We show that this approach allows
a reasonably clean separation of radiation from the shell and from fluid
motions in the star, and provides broad flexibility in the location and
timescale of perturbations driving the fluid motions. With this model we
compare the relativistic and Newtonian results for the generation of even
parity gravitational waves from constant density models. Our results suggest
that relativistic effects will not be important in computations of the
gravitational emission except possibly in the case of excitation of the neutron
star on very short time scales.
| [
{
"created": "Tue, 22 Feb 2000 23:07:29 GMT",
"version": "v1"
},
{
"created": "Mon, 24 Apr 2000 19:00:40 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Andrade",
"Zeferino",
""
],
[
"Price",
"Richard H.",
""
]
] | A perturbing shell is introduced as a device for studying the excitation of fluid motions in relativistic stellar models. We show that this approach allows a reasonably clean separation of radiation from the shell and from fluid motions in the star, and provides broad flexibility in the location and timescale of perturbations driving the fluid motions. With this model we compare the relativistic and Newtonian results for the generation of even parity gravitational waves from constant density models. Our results suggest that relativistic effects will not be important in computations of the gravitational emission except possibly in the case of excitation of the neutron star on very short time scales. |
gr-qc/9810049 | Inyong Cho | Inyong Cho and Alexander Vilenkin | Gravitational field of vacuumless defects | 19 pages, REVTeX, 6 Postscript figures | Phys. Rev. D 59, 063510 (1999) | 10.1103/PhysRevD.59.063510 | null | gr-qc astro-ph hep-ph hep-th | null | It has been recently shown that topological defects can arise in symmetry
breaking models where the scalar field potential $V(\phi)$ has no minima and is
a monotonically decreasing function of $|\phi|$. Here we study the
gravitational fields produced by such vacuumless defects in the cases of both
global and gauge symmetry breaking. We find that a global monopole has a
strongly repulsive gravitational field, and its spacetime has an event horizon
similar to that in de Sitter space. A gauge monopole spacetime is essentially
that of a magnetically charged black hole. The gravitational field of a global
string is repulsive and that of a gauge string is attractive at small distances
and repulsive at large distances. Both gauge and global string spacetimes have
singularities at a finite distance from the string core.
| [
{
"created": "Thu, 15 Oct 1998 00:14:02 GMT",
"version": "v1"
}
] | 2016-08-25 | [
[
"Cho",
"Inyong",
""
],
[
"Vilenkin",
"Alexander",
""
]
] | It has been recently shown that topological defects can arise in symmetry breaking models where the scalar field potential $V(\phi)$ has no minima and is a monotonically decreasing function of $|\phi|$. Here we study the gravitational fields produced by such vacuumless defects in the cases of both global and gauge symmetry breaking. We find that a global monopole has a strongly repulsive gravitational field, and its spacetime has an event horizon similar to that in de Sitter space. A gauge monopole spacetime is essentially that of a magnetically charged black hole. The gravitational field of a global string is repulsive and that of a gauge string is attractive at small distances and repulsive at large distances. Both gauge and global string spacetimes have singularities at a finite distance from the string core. |
gr-qc/0312024 | Robert Bock | Robert Davis Bock | Local Scale Invariance and General Relativity | References Added | Int.J.Theor.Phys. 42 (2003) 1835-1847 | null | null | gr-qc | null | According to the theory of unimodular relativity developed by Anderson and
Finkelstein, the equations of general relativity with a cosmological constant
are composed of two independent equations, one which determines the null-cone
structure of space-time, another which determines the measure structure of
space-time. The field equations that follow from the restricted variational
principle of this version of general relativity only determine the null-cone
structure and are globally scale-invariant and scale-free. We show that the
electromagnetic field may be viewed as a compensating gauge field that
guarantees local scale invariance of these field equations. In this way, Weyl's
geometry is revived. However, the two principle objections to Weyl's theory do
not apply to the present formulation: the Lagrangian remains first order in the
curvature scalar and the non-integrability of length only applies to the
null-cone structure.
| [
{
"created": "Thu, 4 Dec 2003 03:30:51 GMT",
"version": "v1"
},
{
"created": "Fri, 5 Dec 2003 18:13:38 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Bock",
"Robert Davis",
""
]
] | According to the theory of unimodular relativity developed by Anderson and Finkelstein, the equations of general relativity with a cosmological constant are composed of two independent equations, one which determines the null-cone structure of space-time, another which determines the measure structure of space-time. The field equations that follow from the restricted variational principle of this version of general relativity only determine the null-cone structure and are globally scale-invariant and scale-free. We show that the electromagnetic field may be viewed as a compensating gauge field that guarantees local scale invariance of these field equations. In this way, Weyl's geometry is revived. However, the two principle objections to Weyl's theory do not apply to the present formulation: the Lagrangian remains first order in the curvature scalar and the non-integrability of length only applies to the null-cone structure. |
2404.19213 | Xiao Zhang | Hequn Zhang, Xiao Zhang | Nonexistence of Majorana fermions in Kerr-Newman type spacetimes with
nontrivial charge | 8 pages | null | null | null | gr-qc hep-th math.DG | http://creativecommons.org/publicdomain/zero/1.0/ | In this short paper, we study Majorana fermions in terms of a modified
Chandrasekhar's separation for the Dirac equation in Kerr-Newman-type
spacetimes. If the electric charge or magnetic charge is nonzero, we show that
nontrivial differentiable time-periodic Majorana fermions do not exist outside
the event horizon in Kerr-Newman and Kerr-Newman-AdS spacetimes, and between
the event horizon and the cosmological horizon in Kerr-Newman-dS spacetime.
| [
{
"created": "Tue, 30 Apr 2024 02:29:38 GMT",
"version": "v1"
}
] | 2024-05-01 | [
[
"Zhang",
"Hequn",
""
],
[
"Zhang",
"Xiao",
""
]
] | In this short paper, we study Majorana fermions in terms of a modified Chandrasekhar's separation for the Dirac equation in Kerr-Newman-type spacetimes. If the electric charge or magnetic charge is nonzero, we show that nontrivial differentiable time-periodic Majorana fermions do not exist outside the event horizon in Kerr-Newman and Kerr-Newman-AdS spacetimes, and between the event horizon and the cosmological horizon in Kerr-Newman-dS spacetime. |
1610.07979 | Mauricio Bellini | Mauricio Bellini (IFIMAR - CONICET and UNMdP) | Pre-inflation: origin of the Universe from a topological phase
transition | version accepted in Phys. Lett. B | null | 10.1016/j.physletb.2017.05.049 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | I study a model which describes the birth of the universe using a global
topological phase transition with a complex manifold where the time, $\tau$, is
considered as a complex variable. Before the big bang $\tau$ is a purely
imaginary variable so that the space can be considered as Euclidean. The phase
transition from a pre-inflation to inflation is examined by studying the
dynamical rotation of the time on the complex plane. Back-reaction effects are
exactly calculated using Relativistic Quantum Geometry.
| [
{
"created": "Tue, 25 Oct 2016 17:31:08 GMT",
"version": "v1"
},
{
"created": "Wed, 17 May 2017 20:14:37 GMT",
"version": "v2"
}
] | 2017-05-24 | [
[
"Bellini",
"Mauricio",
"",
"IFIMAR - CONICET and UNMdP"
]
] | I study a model which describes the birth of the universe using a global topological phase transition with a complex manifold where the time, $\tau$, is considered as a complex variable. Before the big bang $\tau$ is a purely imaginary variable so that the space can be considered as Euclidean. The phase transition from a pre-inflation to inflation is examined by studying the dynamical rotation of the time on the complex plane. Back-reaction effects are exactly calculated using Relativistic Quantum Geometry. |
gr-qc/9606091 | Thomas Thiemann | T. Thiemann | Closed formula for the matrix elements of the volume operator in
canonical quantum gravity | 27 pages, Latex | J.Math.Phys. 39 (1998) 3347-3371 | 10.1063/1.532259 | HUTMP-96/B-353 | gr-qc | null | We derive a closed formula for the matrix elements of the volume operator for
canonical Lorentzian quantum gravity in four spacetime dimensions in the
continuum in a spin-network basis. We also display a new technique of
regularization which is state dependent but we are forced to it in order to
maintain diffeomorphism covariance and in that sense it is natural. We arrive
naturally at the expression for the volume operator as defined by Ashtekar and
Lewandowski up to a state independent factor.
| [
{
"created": "Sat, 29 Jun 1996 23:29:28 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Thiemann",
"T.",
""
]
] | We derive a closed formula for the matrix elements of the volume operator for canonical Lorentzian quantum gravity in four spacetime dimensions in the continuum in a spin-network basis. We also display a new technique of regularization which is state dependent but we are forced to it in order to maintain diffeomorphism covariance and in that sense it is natural. We arrive naturally at the expression for the volume operator as defined by Ashtekar and Lewandowski up to a state independent factor. |
1407.7463 | Igor Tanatarov | I.V. Tanatarov and O.B. Zaslavskii | Banados-Silk-West effect with nongeodesic particles: Nonextremal
horizons | v2 matches the published version; revtex4, 11 pages | Phys. Rev. D 90, 067502 (2014) | 10.1103/PhysRevD.90.067502 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | When two particles collide near a black hole, the energy in their center of
mass frame can, under certain conditions, grow unbounded. This is the
Banados-Silk-West effect. We show that this effect retains its validity even if
some force acts on a particle, provided some reasonable and weak restrictions
are imposed on this force. In the present work we discuss the case of
nonextremal horizons. The result under discussion is similar to that for
extremal horizons considered in our previous work.
| [
{
"created": "Mon, 28 Jul 2014 16:21:34 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Sep 2014 21:13:47 GMT",
"version": "v2"
}
] | 2014-09-08 | [
[
"Tanatarov",
"I. V.",
""
],
[
"Zaslavskii",
"O. B.",
""
]
] | When two particles collide near a black hole, the energy in their center of mass frame can, under certain conditions, grow unbounded. This is the Banados-Silk-West effect. We show that this effect retains its validity even if some force acts on a particle, provided some reasonable and weak restrictions are imposed on this force. In the present work we discuss the case of nonextremal horizons. The result under discussion is similar to that for extremal horizons considered in our previous work. |
2012.07075 | Adamantia Zampeli | Andronikos Paliathanasis, Adamantia Zampeli, Theodosios
Christodoulakis, M.T. Mustafa | Quantization of the Szekeres spacetime through generalized symmetries | Prepared for the proceedings of the Fifteenth Marcel Grossmann
Meeting - MG15 | null | null | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present the effect of the quantum corrections on the Szekeres spacetime, a
system important for the study of the inhomogeneities of the pre-inflationary
era of the universe. The study is performed in the context of canonical
quantisation in the presence of symmetries. We construct an effective classical
Lagrangian and impose the quantum version of its classical integrals of motion
on the wave function. The interpretational scheme of the quantum solution is
that of Bohmian mechanics, in which one can avoid the unitarity problem of
quantum cosmology. We discuss our results in this context.
| [
{
"created": "Sun, 13 Dec 2020 14:49:53 GMT",
"version": "v1"
}
] | 2020-12-15 | [
[
"Paliathanasis",
"Andronikos",
""
],
[
"Zampeli",
"Adamantia",
""
],
[
"Christodoulakis",
"Theodosios",
""
],
[
"Mustafa",
"M. T.",
""
]
] | We present the effect of the quantum corrections on the Szekeres spacetime, a system important for the study of the inhomogeneities of the pre-inflationary era of the universe. The study is performed in the context of canonical quantisation in the presence of symmetries. We construct an effective classical Lagrangian and impose the quantum version of its classical integrals of motion on the wave function. The interpretational scheme of the quantum solution is that of Bohmian mechanics, in which one can avoid the unitarity problem of quantum cosmology. We discuss our results in this context. |
1707.03614 | Golam Mortuza Hossain | Subhajit Barman, Golam Mortuza Hossain and Chiranjeeb Singha | An exact derivation of the Hawking effect in canonical formulation | 11 pages, 3 figures, revtex4 | Phys. Rev. D 97, 025016 (2018) | 10.1103/PhysRevD.97.025016 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Hawking effect is one of the most extensively studied topics in modern
physics. Yet it remains relatively under-explored within the framework of
canonical quantization. The key difficulty lies in the fact that the Hawking
effect is principally understood using the relation between the ingoing modes
which leave past null infinity and the outgoing modes which arrive at future
null infinity. Naturally, these modes are described using advanced and retarded
null coordinates instead of the usual Schwarzschild coordinates. However, null
coordinates do not lead to a true Hamiltonian that describes the evolution of
these modes. In order to overcome these hurdles in a canonical formulation, we
introduce here a set of near-null coordinates which allows one to perform an
exact Hamiltonian-based derivation of the Hawking effect. This derivation opens
up an avenue to explore the Hawking effect using different canonical
quantization methods such as polymer quantization.
| [
{
"created": "Wed, 12 Jul 2017 09:33:56 GMT",
"version": "v1"
}
] | 2018-01-31 | [
[
"Barman",
"Subhajit",
""
],
[
"Hossain",
"Golam Mortuza",
""
],
[
"Singha",
"Chiranjeeb",
""
]
] | The Hawking effect is one of the most extensively studied topics in modern physics. Yet it remains relatively under-explored within the framework of canonical quantization. The key difficulty lies in the fact that the Hawking effect is principally understood using the relation between the ingoing modes which leave past null infinity and the outgoing modes which arrive at future null infinity. Naturally, these modes are described using advanced and retarded null coordinates instead of the usual Schwarzschild coordinates. However, null coordinates do not lead to a true Hamiltonian that describes the evolution of these modes. In order to overcome these hurdles in a canonical formulation, we introduce here a set of near-null coordinates which allows one to perform an exact Hamiltonian-based derivation of the Hawking effect. This derivation opens up an avenue to explore the Hawking effect using different canonical quantization methods such as polymer quantization. |
2211.09489 | Tomoaki Murata | Tomoaki Murata, Tomohiro Fujita, and Tsutomu Kobayashi | How does SU($N$)-natural inflation isotropize the universe? | 18 pages, 11 figures | Phys. Rev. D 107, 043508 (2023) | 10.1103/PhysRevD.107.043508 | RUP-22-23 | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | We study the homogeneous and anisotropic dynamics of pseudoscalar inflation
coupled to an SU($N$) gauge field. To see how the initially anisotropic
universe is isotropized in such an inflation model, we derive the equations to
obtain axisymmetric SU($N$) gauge field configurations in Bianchi type-I
geometry and discuss a method to identify their isotropic subsets which are the
candidates of their late-time attractor. Each isotropic solution is
characterized by the corresponding SU(2) subalgebra of the SU($N$) algebra. It
is shown numerically that the isotropic universe is a universal late-time
attractor in the case of the SU(3) gauge field. Interestingly, we find that a
transition between the two distinct gauge-field configurations characterized by
different SU(2) subalgebras can occur during inflation. We clarify the
conditions for this to occur. This transition could leave an observable imprint
on the CMB and the primordial gravitational wave background.
| [
{
"created": "Thu, 17 Nov 2022 12:15:49 GMT",
"version": "v1"
},
{
"created": "Fri, 10 Feb 2023 01:10:26 GMT",
"version": "v2"
}
] | 2023-02-13 | [
[
"Murata",
"Tomoaki",
""
],
[
"Fujita",
"Tomohiro",
""
],
[
"Kobayashi",
"Tsutomu",
""
]
] | We study the homogeneous and anisotropic dynamics of pseudoscalar inflation coupled to an SU($N$) gauge field. To see how the initially anisotropic universe is isotropized in such an inflation model, we derive the equations to obtain axisymmetric SU($N$) gauge field configurations in Bianchi type-I geometry and discuss a method to identify their isotropic subsets which are the candidates of their late-time attractor. Each isotropic solution is characterized by the corresponding SU(2) subalgebra of the SU($N$) algebra. It is shown numerically that the isotropic universe is a universal late-time attractor in the case of the SU(3) gauge field. Interestingly, we find that a transition between the two distinct gauge-field configurations characterized by different SU(2) subalgebras can occur during inflation. We clarify the conditions for this to occur. This transition could leave an observable imprint on the CMB and the primordial gravitational wave background. |
0904.0065 | Hongsheng Zhang | Hongsheng Zhang and Hyerim Noh | N-dimensional plane symmetric solution with perfect fluid source | 9 pages, 1 table; v2: 2 references added | Phys.Lett.B671:428-434,2009 | 10.1016/j.physletb.2008.12.057 | null | gr-qc astro-ph.CO hep-ph hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A new class of plane symmetric solution sourced by a perfect fluid is found
in our recent work. An n-dimensional ($n\geq 4$) global plane symmetric
solution of Einstein field equation generated by a perfect fluid source is
investigated, which is the direct generalization of our previous 4-dimensional
solution. One time-like Killing vector and $(n-2)(n-1)/2$ space-like Killing
vectors, which span a Euclidean group $G_{(n-2)(n-1)/2}$, are permitted in this
solution. The regions of the parameters constrained by weak, strong and
dominant energy conditions for the source are studied. The boundary condition
to match to n-dimensional Taub metric and Minkowski metric are analyzed
respectively.
| [
{
"created": "Wed, 1 Apr 2009 06:04:26 GMT",
"version": "v1"
},
{
"created": "Wed, 15 Jul 2009 05:41:17 GMT",
"version": "v2"
}
] | 2011-03-28 | [
[
"Zhang",
"Hongsheng",
""
],
[
"Noh",
"Hyerim",
""
]
] | A new class of plane symmetric solution sourced by a perfect fluid is found in our recent work. An n-dimensional ($n\geq 4$) global plane symmetric solution of Einstein field equation generated by a perfect fluid source is investigated, which is the direct generalization of our previous 4-dimensional solution. One time-like Killing vector and $(n-2)(n-1)/2$ space-like Killing vectors, which span a Euclidean group $G_{(n-2)(n-1)/2}$, are permitted in this solution. The regions of the parameters constrained by weak, strong and dominant energy conditions for the source are studied. The boundary condition to match to n-dimensional Taub metric and Minkowski metric are analyzed respectively. |
gr-qc/9812010 | A. Puncher | J. Wainwright, M. J. Hancock, C. Uggla | Asymptotic self-similarity breaking at late times in cosmology | 29 pages | Class.Quant.Grav. 16 (1999) 2577-2598 | 10.1088/0264-9381/16/8/302 | null | gr-qc | null | We study the late time evolution of a class of exact anisotropic cosmological
solutions of Einstein's equations, namely spatially homogeneous cosmologies of
Bianchi type VII$_0$ with a perfect fluid source. We show that, in contrast to
models of Bianchi type VII$_h$ which are asymptotically self-similar at late
times, Bianchi VII$_0$ models undergo a complicated type of self-similarity
breaking. This symmetry breaking affects the late time isotropization that
occurs in these models in a significant way: if the equation of state parameter
$\gamma$ satisfies $\gamma \leq 4/3$ the models isotropize as regards the shear
but not as regards the Weyl curvature. Indeed these models exhibit a new
dynamical feature that we refer to as Weyl curvature dominance: the Weyl
curvature dominates the dynamics at late times. By viewing the evolution from a
dynamical systems perspective we show that, despite the special nature of the
class of models under consideration, this behaviour has implications for more
general models.
| [
{
"created": "Wed, 2 Dec 1998 18:52:39 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Wainwright",
"J.",
""
],
[
"Hancock",
"M. J.",
""
],
[
"Uggla",
"C.",
""
]
] | We study the late time evolution of a class of exact anisotropic cosmological solutions of Einstein's equations, namely spatially homogeneous cosmologies of Bianchi type VII$_0$ with a perfect fluid source. We show that, in contrast to models of Bianchi type VII$_h$ which are asymptotically self-similar at late times, Bianchi VII$_0$ models undergo a complicated type of self-similarity breaking. This symmetry breaking affects the late time isotropization that occurs in these models in a significant way: if the equation of state parameter $\gamma$ satisfies $\gamma \leq 4/3$ the models isotropize as regards the shear but not as regards the Weyl curvature. Indeed these models exhibit a new dynamical feature that we refer to as Weyl curvature dominance: the Weyl curvature dominates the dynamics at late times. By viewing the evolution from a dynamical systems perspective we show that, despite the special nature of the class of models under consideration, this behaviour has implications for more general models. |
2110.03377 | Daniil Krichevskiy | Stanislav Alexeyev, Daniil Krichevskiy, Boris Latosh | Gravity models with nonlinear symmetry realization | null | Alexeyev, S.; Krichevskiy, D.; Latosh, B. Gravity Models with
Nonlinear Symmetry Realization. Universe 2021, 7, 501 | 10.3390/universe7120501 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Three models with nonlinear realizations of conformal symmetry are discussed.
The simplest model can only describe a universe expanding with a deceleration
and does not include inflation. The other models are equivalent up to a
variables reparametrization. All these models contain ghost degrees of freedom
which may be excluded with an additional symmetry of the target space.
| [
{
"created": "Thu, 7 Oct 2021 12:14:29 GMT",
"version": "v1"
}
] | 2021-12-23 | [
[
"Alexeyev",
"Stanislav",
""
],
[
"Krichevskiy",
"Daniil",
""
],
[
"Latosh",
"Boris",
""
]
] | Three models with nonlinear realizations of conformal symmetry are discussed. The simplest model can only describe a universe expanding with a deceleration and does not include inflation. The other models are equivalent up to a variables reparametrization. All these models contain ghost degrees of freedom which may be excluded with an additional symmetry of the target space. |
2105.03970 | Genly Le\'on | Andronikos Paliathanasis, Megandhren Govender and Genly Leon | Temporal evolution of a radiating star via Lie symmetries | 8 pages, 7 figures | Eur.Phys.J.C 81 (2021) 8, 718 | 10.1140/epjc/s10052-021-09521-x | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we present for the first time the general solution of the
temporal evolution equation arising from the matching of a conformally flat
interior to the Vaidya solution. This problem was first articulated by Banerjee
et al. (A. Banerjee, S. B. Dutta Choudhury, and Bidyut K. Bhui, Phys. Rev. D,
40 (670) 1989) in which they provided a particular solution to the temporal
equation. This simple exact solution has been widely utilized in modeling
dissipative collapse with the most notable result being a prediction of the
avoidance of the horizon as the collapse proceeds. We study the dynamics of
dissipative collapse arising from the general solution obtained via the method
of symmetries and of the singularity analysis. We show that the end-state of
collapse for our model is significantly different from the widely used linear
solution.
| [
{
"created": "Sun, 9 May 2021 17:22:28 GMT",
"version": "v1"
},
{
"created": "Fri, 8 Apr 2022 20:00:46 GMT",
"version": "v2"
}
] | 2022-04-12 | [
[
"Paliathanasis",
"Andronikos",
""
],
[
"Govender",
"Megandhren",
""
],
[
"Leon",
"Genly",
""
]
] | In this work, we present for the first time the general solution of the temporal evolution equation arising from the matching of a conformally flat interior to the Vaidya solution. This problem was first articulated by Banerjee et al. (A. Banerjee, S. B. Dutta Choudhury, and Bidyut K. Bhui, Phys. Rev. D, 40 (670) 1989) in which they provided a particular solution to the temporal equation. This simple exact solution has been widely utilized in modeling dissipative collapse with the most notable result being a prediction of the avoidance of the horizon as the collapse proceeds. We study the dynamics of dissipative collapse arising from the general solution obtained via the method of symmetries and of the singularity analysis. We show that the end-state of collapse for our model is significantly different from the widely used linear solution. |
1709.09039 | Mehrab Momennia | Seyed Hossein Hendi, Mehrab Momennia | Reentrant phase transition of Born-Infeld-dilaton black holes | 9 pages, 5 figures, 2 tables. A section added. Accepted in EPJC | Eur. Phys. J. C 78 (2018) 800 | 10.1140/epjc/s10052-018-6278-y | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We explore a novel reentrant phase transition of four-dimensional
Born-Infeld-dilaton black hole in which the first order phase transition modify
into a zeroth order phase transition below the critical point. Working in the
extended phase space with regarding the cosmological constant as a pressure, we
study the reentrant behavior of phase transition in the canonical ensemble. We
show that these black holes enjoy a zeroth order intermediate-small black hole
phase transition as well as a first order phase transition between small and
large black holes for a narrow range of temperatures and pressures. We also
find that the standard first order small-large black hole phase transition can
modify into a zeroth order type. This zeroth order phase transition stands
between the critical point and the first order phase transition region. We
discuss the significant effect of the scalar field (dilaton) on the mentioned
interesting treatment.
| [
{
"created": "Sun, 24 Sep 2017 17:50:42 GMT",
"version": "v1"
},
{
"created": "Sat, 22 Sep 2018 19:38:21 GMT",
"version": "v2"
}
] | 2019-05-21 | [
[
"Hendi",
"Seyed Hossein",
""
],
[
"Momennia",
"Mehrab",
""
]
] | We explore a novel reentrant phase transition of four-dimensional Born-Infeld-dilaton black hole in which the first order phase transition modify into a zeroth order phase transition below the critical point. Working in the extended phase space with regarding the cosmological constant as a pressure, we study the reentrant behavior of phase transition in the canonical ensemble. We show that these black holes enjoy a zeroth order intermediate-small black hole phase transition as well as a first order phase transition between small and large black holes for a narrow range of temperatures and pressures. We also find that the standard first order small-large black hole phase transition can modify into a zeroth order type. This zeroth order phase transition stands between the critical point and the first order phase transition region. We discuss the significant effect of the scalar field (dilaton) on the mentioned interesting treatment. |
gr-qc/9804016 | Wladimir Belayev | W.B.Belayev | About model of the Universe with accelerated movement of the time | 4 pages | null | null | NTV-98-03 | gr-qc | null | Cosmological model based on metric of Fridmann-Robertson-Walker with
permanent size and acceleration of time is considered. The problem of the dark
matter is analyzed within this model .
| [
{
"created": "Mon, 6 Apr 1998 15:20:06 GMT",
"version": "v1"
},
{
"created": "Thu, 14 May 1998 06:35:38 GMT",
"version": "v2"
},
{
"created": "Tue, 7 Jul 1998 11:56:59 GMT",
"version": "v3"
},
{
"created": "Tue, 30 Mar 1999 17:59:29 GMT",
"version": "v4"
}
] | 2007-05-23 | [
[
"Belayev",
"W. B.",
""
]
] | Cosmological model based on metric of Fridmann-Robertson-Walker with permanent size and acceleration of time is considered. The problem of the dark matter is analyzed within this model . |
gr-qc/0107077 | Roberto Casadio | R. Casadio, A. Gruppuso | On boundary terms and conformal transformations in curved space-times | LaTeX 2e, 12 pages, no figures | Int.J.Mod.Phys. D11 (2002) 703-714 | 10.1142/S0218271802001913 | null | gr-qc hep-th | null | We intend to clarify the interplay between boundary terms and conformal
transformations in scalar-tensor theories of gravity. We first consider the
action for pure gravity in five dimensions and show that, on compactifing a la
Kaluza-Klein to four dimensions, one obtains the correct boundary terms in the
Jordan (or String) Frame form of the Brans-Dicke action. Further, we analyze
how the boundary terms change under the conformal transformations which lead to
the Pauli (or Einstein) frame and to the non-minimally coupled massless scalar
field. In particular, we study the behaviour of the total energy in
asymptotically flat space-times as it results from surface terms in the
Hamiltonian formalism.
| [
{
"created": "Tue, 24 Jul 2001 08:27:46 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Casadio",
"R.",
""
],
[
"Gruppuso",
"A.",
""
]
] | We intend to clarify the interplay between boundary terms and conformal transformations in scalar-tensor theories of gravity. We first consider the action for pure gravity in five dimensions and show that, on compactifing a la Kaluza-Klein to four dimensions, one obtains the correct boundary terms in the Jordan (or String) Frame form of the Brans-Dicke action. Further, we analyze how the boundary terms change under the conformal transformations which lead to the Pauli (or Einstein) frame and to the non-minimally coupled massless scalar field. In particular, we study the behaviour of the total energy in asymptotically flat space-times as it results from surface terms in the Hamiltonian formalism. |
2002.08183 | Jackson Levi Said | Gabriel Farrugia, Jackson Levi Said, and Andrew Finch | Gravitoelectromagnetism, Solar System Test and Weak-Field Solutions in
$f(T,B)$ Gravity with Observational Constraints | 15 pages | Universe 2020, 6(2), 34 | 10.3390/universe6020034 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitomagnetism characterize phenomena in the weak field limit within the
context of rotating systems. These are mainly manifested in the geodetic and
Lense-Thirring effects. The geodetic effect describes the precession of the
spin of a gyroscope in orbit about a massive static central object, while the
Lense-Thirring effect expresses the analogous effect for the precession of the
orbit about a rotating source. In this work, we explore these effects in the
framework of Teleparallel Gravity and investigate how these effects may impact
recent and future missions. We find that teleparallel theories of gravity may
have an important impact on these effects which may constrain potential models
within these theories.
| [
{
"created": "Tue, 18 Feb 2020 17:22:46 GMT",
"version": "v1"
},
{
"created": "Thu, 27 Feb 2020 08:58:40 GMT",
"version": "v2"
}
] | 2020-02-28 | [
[
"Farrugia",
"Gabriel",
""
],
[
"Said",
"Jackson Levi",
""
],
[
"Finch",
"Andrew",
""
]
] | Gravitomagnetism characterize phenomena in the weak field limit within the context of rotating systems. These are mainly manifested in the geodetic and Lense-Thirring effects. The geodetic effect describes the precession of the spin of a gyroscope in orbit about a massive static central object, while the Lense-Thirring effect expresses the analogous effect for the precession of the orbit about a rotating source. In this work, we explore these effects in the framework of Teleparallel Gravity and investigate how these effects may impact recent and future missions. We find that teleparallel theories of gravity may have an important impact on these effects which may constrain potential models within these theories. |
1912.06887 | Daniele Bertacca DR. | Daniele Bertacca | Generalisation of the Kaiser Rocket effect in general relativity in the
wide-angle galaxy 2-point correlation function | 24 pages, 12 figures. Matches published version | null | 10.1142/S0218271820500856 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study wide-angle correlations in the galaxy power spectrum in redshift
space, including all general relativistic effects and the Kaiser Rocket effect
in general relativity. We find that the Kaiser Rocket effect becomes important
on large scales and at high redshifts, and leads to new contributions in
wide-angle correlations. We believe this effect might be very important for
future large volume surveys.
| [
{
"created": "Sat, 14 Dec 2019 17:33:43 GMT",
"version": "v1"
},
{
"created": "Tue, 25 Aug 2020 12:53:02 GMT",
"version": "v2"
}
] | 2020-08-26 | [
[
"Bertacca",
"Daniele",
""
]
] | We study wide-angle correlations in the galaxy power spectrum in redshift space, including all general relativistic effects and the Kaiser Rocket effect in general relativity. We find that the Kaiser Rocket effect becomes important on large scales and at high redshifts, and leads to new contributions in wide-angle correlations. We believe this effect might be very important for future large volume surveys. |
1506.07907 | Steven L. Liebling | Alex Buchel and Stephen R. Green and Luis Lehner and Steven L.
Liebling | Reply to "Comment on two-mode stability islands around AdS" | 2 pages, 1 figure | Phys. Rev. Lett. 115, 049102 (2015) | 10.1103/PhysRevLett.115.049102 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We respond to the criticisms of a recent comment by Bizo\'n and Rostworowski
[arXiv:1410.2631].
| [
{
"created": "Thu, 25 Jun 2015 21:57:58 GMT",
"version": "v1"
}
] | 2015-07-30 | [
[
"Buchel",
"Alex",
""
],
[
"Green",
"Stephen R.",
""
],
[
"Lehner",
"Luis",
""
],
[
"Liebling",
"Steven L.",
""
]
] | We respond to the criticisms of a recent comment by Bizo\'n and Rostworowski [arXiv:1410.2631]. |
gr-qc/0105031 | Lawrence E. Kidder | Lawrence E. Kidder, Mark A. Scheel, and Saul A. Teukolsky | Extending the lifetime of 3D black hole computations with a new
hyperbolic system of evolution equations | 11 pages, 2 figures, submitted to PRD | Phys.Rev.D64:064017,2001 | 10.1103/PhysRevD.64.064017 | null | gr-qc | null | We present a new many-parameter family of hyperbolic representations of
Einstein's equations, which we obtain by a straightforward generalization of
previously known systems. We solve the resulting evolution equations
numerically for a Schwarzschild black hole in three spatial dimensions, and
find that the stability of the simulation is strongly dependent on the form of
the equations (i.e. the choice of parameters of the hyperbolic system),
independent of the numerics. For an appropriate range of parameters we can
evolve a single 3D black hole to $t \simeq 600 M$ -- $1300 M$, and are
apparently limited by constraint-violating solutions of the evolution
equations. We expect that our method should result in comparable times for
evolutions of a binary black hole system.
| [
{
"created": "Tue, 8 May 2001 19:24:59 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Kidder",
"Lawrence E.",
""
],
[
"Scheel",
"Mark A.",
""
],
[
"Teukolsky",
"Saul A.",
""
]
] | We present a new many-parameter family of hyperbolic representations of Einstein's equations, which we obtain by a straightforward generalization of previously known systems. We solve the resulting evolution equations numerically for a Schwarzschild black hole in three spatial dimensions, and find that the stability of the simulation is strongly dependent on the form of the equations (i.e. the choice of parameters of the hyperbolic system), independent of the numerics. For an appropriate range of parameters we can evolve a single 3D black hole to $t \simeq 600 M$ -- $1300 M$, and are apparently limited by constraint-violating solutions of the evolution equations. We expect that our method should result in comparable times for evolutions of a binary black hole system. |
gr-qc/9805089 | Angelo Tartaglia | G. Rizzi, A. Tartaglia (Dipartimento di Fisica, Politecnico Torino,
Italy) | Speed of light on rotating platforms | Latex, 2 figures | null | null | Centro Volterra, 299/97 | gr-qc | null | It is often taken for granted that on board a rotating disk it is possible to
operate a \QTR{it}{global}3+1 splitting of space-time, such that both lengths
and time intervals are \QTR{it}{uniquely} defined in terms of measurements
performed by real rods and real clocks at rest on the platform. This paper
shows that this assumption, although widespread and apparently trivial, leads
to an anisotropy of the velocity of two light beams travelling in opposite
directions along the rim of the disk; which in turn implies some recently
pointed out paradoxical consequences undermining the self-consistency of the
Special Theory of Relativity (SRT). A correct application of the SRT solves the
problem and recovers complete internal consistency for the theory. As an
immediate consequence, it is shown that the Sagnac effect only depends on the
non homogeneity of time on the platform and has nothing to do with any
anisotropy of the speed of light along the rim of the disk, contrary to an
incorrect but widely supported idea.
| [
{
"created": "Mon, 25 May 1998 09:22:00 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Rizzi",
"G.",
"",
"Dipartimento di Fisica, Politecnico Torino,\n Italy"
],
[
"Tartaglia",
"A.",
"",
"Dipartimento di Fisica, Politecnico Torino,\n Italy"
]
] | It is often taken for granted that on board a rotating disk it is possible to operate a \QTR{it}{global}3+1 splitting of space-time, such that both lengths and time intervals are \QTR{it}{uniquely} defined in terms of measurements performed by real rods and real clocks at rest on the platform. This paper shows that this assumption, although widespread and apparently trivial, leads to an anisotropy of the velocity of two light beams travelling in opposite directions along the rim of the disk; which in turn implies some recently pointed out paradoxical consequences undermining the self-consistency of the Special Theory of Relativity (SRT). A correct application of the SRT solves the problem and recovers complete internal consistency for the theory. As an immediate consequence, it is shown that the Sagnac effect only depends on the non homogeneity of time on the platform and has nothing to do with any anisotropy of the speed of light along the rim of the disk, contrary to an incorrect but widely supported idea. |
2212.14362 | Xian Gao | Zheng Chen, Yang Yu and Xian Gao | Polarized gravitational waves in the parity violating
scalar-nonmetricity theory | 12 pages, no figure | null | 10.1088/1475-7516/2023/06/001 | null | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | There has been increasing interest in investigating the possible parity
violating features in the gravity theory and on the cosmological scales. In
this work, we consider a class of scalar-nonmetricity theory, of which the
Lagrangian is polynomial built of the nonmetricity tensor and a scalar field.
The nonmetricity tensor is coupled with the scalar field through its first
order derivative. Besides the monomials that are quadratic order in the
nonmetricity tensor, we also construct monomials that are cubic order in the
nonmetricity tensor in both the parity preserving and violating cases. These
monomials act as the non-canonical (i.e., non-quadratic) kinetic terms for the
spacetime metric, and will change the behavior in the propagation of the
gravitational waves. We find that the gravitational waves are generally
polarized, which present both the amplitude and velocity birefringence features
due to the parity violation of the theory. Due to the term proportional to
$1/k$ in the phase velocities, one of the two polarization modes suffers from
the gradient instability on large scales.
| [
{
"created": "Thu, 29 Dec 2022 16:25:11 GMT",
"version": "v1"
}
] | 2023-06-14 | [
[
"Chen",
"Zheng",
""
],
[
"Yu",
"Yang",
""
],
[
"Gao",
"Xian",
""
]
] | There has been increasing interest in investigating the possible parity violating features in the gravity theory and on the cosmological scales. In this work, we consider a class of scalar-nonmetricity theory, of which the Lagrangian is polynomial built of the nonmetricity tensor and a scalar field. The nonmetricity tensor is coupled with the scalar field through its first order derivative. Besides the monomials that are quadratic order in the nonmetricity tensor, we also construct monomials that are cubic order in the nonmetricity tensor in both the parity preserving and violating cases. These monomials act as the non-canonical (i.e., non-quadratic) kinetic terms for the spacetime metric, and will change the behavior in the propagation of the gravitational waves. We find that the gravitational waves are generally polarized, which present both the amplitude and velocity birefringence features due to the parity violation of the theory. Due to the term proportional to $1/k$ in the phase velocities, one of the two polarization modes suffers from the gradient instability on large scales. |
0707.1972 | Stefan Haesen | Stefan Haesen and Miguel Ortega | Boost invariant marginally trapped surfaces in Minkowski 4-space | 13 pages, comment added in section 2 | Class.Quant.Grav.24:5441-5452,2007 | 10.1088/0264-9381/24/22/009 | null | gr-qc | null | The extremal and partly marginally trapped surfaces in Minkowski 4-space,
which are invariant under the group of boost isometries, are classified.
Moreover, it is shown that there do not exist extremal surfaces of this kind
with constant Gaussian curvature. A procedure is given in order to construct a
partly marginally trapped surface by gluing two marginally trapped surfaces
which are invariant under the group of boost isometries. As an application, a
proper star-surface is constructed.
| [
{
"created": "Fri, 13 Jul 2007 11:07:08 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Oct 2007 07:30:33 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Haesen",
"Stefan",
""
],
[
"Ortega",
"Miguel",
""
]
] | The extremal and partly marginally trapped surfaces in Minkowski 4-space, which are invariant under the group of boost isometries, are classified. Moreover, it is shown that there do not exist extremal surfaces of this kind with constant Gaussian curvature. A procedure is given in order to construct a partly marginally trapped surface by gluing two marginally trapped surfaces which are invariant under the group of boost isometries. As an application, a proper star-surface is constructed. |
1707.01619 | Maurice H. P. M. van Putten | Maurice H.P.M. van Putten | Galaxy rotation curves and the deceleration parameter in weak gravity | 15 p., 5 figs., based on invited talk Conference Cosmology,
Gravitational waves and Particles, 6-10 Feb., NTU, Singapore (2017) | Mod. Phys. Lett. A, 32, 1730019 (2017) | 10.1142/S0217732317300191 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a theory of weak gravity parameterized by a fundamental frequency
$\omega_0 = \sqrt{1-q}H$ of the cosmoloogical horizon, where $H$ and $q$ denote
the Hubble and, respectively, deceleration parameter. It predicts (i) a $C^0$
onset to weak gravity across accelerations $\alpha = a_{dS}$ in galaxy rotation
curves, where $a_{dS}=cH$ denotes the de Sitter acceleration with velocity of
light $c$, and (ii) fast evolution $Q(z)=dq(z)/dz$ of the deceleration
parameter by $\Lambda=\omega_0^2$ satisfying $Q_0>2.5$, $Q_0=Q(0)$, distinct
from $Q_0\lesssim1$ in $\Lambda$CDM. The first is identified in high resolution
data of Lellie et al.(2017), the second in heterogeneous data on $H(z)$ over
$0<z<2$. A model-independent cubic fit in the second rules out $\Lambda$CDM by
$4.35\sigma$ and obtains $H_0=74.0\pm 2.2$ km s$^{-1}$ Mpc$^{-1}$ consistent
with Riess et al. (2016). Comments on possible experimental tests by the LISA
Pathfinder are included.
| [
{
"created": "Thu, 6 Jul 2017 02:58:43 GMT",
"version": "v1"
}
] | 2017-07-07 | [
[
"van Putten",
"Maurice H. P. M.",
""
]
] | We present a theory of weak gravity parameterized by a fundamental frequency $\omega_0 = \sqrt{1-q}H$ of the cosmoloogical horizon, where $H$ and $q$ denote the Hubble and, respectively, deceleration parameter. It predicts (i) a $C^0$ onset to weak gravity across accelerations $\alpha = a_{dS}$ in galaxy rotation curves, where $a_{dS}=cH$ denotes the de Sitter acceleration with velocity of light $c$, and (ii) fast evolution $Q(z)=dq(z)/dz$ of the deceleration parameter by $\Lambda=\omega_0^2$ satisfying $Q_0>2.5$, $Q_0=Q(0)$, distinct from $Q_0\lesssim1$ in $\Lambda$CDM. The first is identified in high resolution data of Lellie et al.(2017), the second in heterogeneous data on $H(z)$ over $0<z<2$. A model-independent cubic fit in the second rules out $\Lambda$CDM by $4.35\sigma$ and obtains $H_0=74.0\pm 2.2$ km s$^{-1}$ Mpc$^{-1}$ consistent with Riess et al. (2016). Comments on possible experimental tests by the LISA Pathfinder are included. |
2208.11953 | Salah Haouat | M. Bouali and S. Haouat | Particle creation in the presence of minimal length: The time dependent
gauge | null | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | In this paper we have studied the problem of scalar particles pair creation
by a constant electric field in the presence of a minimal length. A closed
expression for the corresponding Green's function is obtained via path integral
approach. Then by projecting this function on the outgoing particle and
antiparticle states we have calculated the probability to create a pair of
particles and the number density of created particles. From this, we have
deduced the modifications brought by the minimal length to Hawking temperature
and black hole entropy. It is shown that the first correction is a logarithmic
term with a negative numerical factor. We have also examined the semiclassical
WKB approximation in the calculation of the pair production rate. The result is
that, unlike the ordinary case, the WKB approximation in the presence of a
minimal length does not give the exact rate even for the constant electric
field.
| [
{
"created": "Thu, 25 Aug 2022 09:19:39 GMT",
"version": "v1"
}
] | 2022-08-26 | [
[
"Bouali",
"M.",
""
],
[
"Haouat",
"S.",
""
]
] | In this paper we have studied the problem of scalar particles pair creation by a constant electric field in the presence of a minimal length. A closed expression for the corresponding Green's function is obtained via path integral approach. Then by projecting this function on the outgoing particle and antiparticle states we have calculated the probability to create a pair of particles and the number density of created particles. From this, we have deduced the modifications brought by the minimal length to Hawking temperature and black hole entropy. It is shown that the first correction is a logarithmic term with a negative numerical factor. We have also examined the semiclassical WKB approximation in the calculation of the pair production rate. The result is that, unlike the ordinary case, the WKB approximation in the presence of a minimal length does not give the exact rate even for the constant electric field. |
gr-qc/0509129 | Eirini Messaritaki | LIGO Scientific Collaboration: B. Abbott et. al | Search for gravitational waves from binary black hole inspirals in LIGO
data | 18 pages, 8 figures | Phys.Rev.D73:062001,2006 | 10.1103/PhysRevD.73.062001 | null | gr-qc | null | We report on a search for gravitational waves from binary black hole
inspirals in the data from the second science run of the LIGO interferometers.
The search focused on binary systems with component masses between 3 and 20
solar masses. Optimally oriented binaries with distances up to 1 Mpc could be
detected with efficiency of at least 90%. We found no events that could be
identified as gravitational waves in the 385.6 hours of data that we searched.
| [
{
"created": "Fri, 30 Sep 2005 17:08:23 GMT",
"version": "v1"
}
] | 2009-09-29 | [
[
"LIGO Scientific Collaboration",
"",
""
],
[
"al",
"B. Abbott et.",
""
]
] | We report on a search for gravitational waves from binary black hole inspirals in the data from the second science run of the LIGO interferometers. The search focused on binary systems with component masses between 3 and 20 solar masses. Optimally oriented binaries with distances up to 1 Mpc could be detected with efficiency of at least 90%. We found no events that could be identified as gravitational waves in the 385.6 hours of data that we searched. |
2106.15138 | Rajesh Kumar | Anjali Pandey, Rajesh Kumar, Sudhir Kumar Srivastava | Spherically Symmetric Gravitational Collapse Of Inhomogeneous Dust Cloud
In The Background Of Dark Energy | null | null | null | null | gr-qc | http://creativecommons.org/licenses/by-sa/4.0/ | The present paper deals with the gravitational collapse of an inhomogeneous
spherical star consisting of dust fluid in the background of dark energy
components with linear equation of state. We discussed the development of
apparent horizon to investigate the black-hole formation in gravitational
collapsing process. The collapsing process is examined first separately for
dust cloud and dark energy and then under the combined effect of dust
interacting with dark energy. It is obtained that when only dust cloud or dark
energy is present the collapse leads to the formation of black-hole under
certain conditions. When both of them are present, collapsing star does not
form black-hole. However when dark energy is considered as cosmological
constant, the collapse leads to black hole formation.
| [
{
"created": "Tue, 29 Jun 2021 07:49:49 GMT",
"version": "v1"
}
] | 2021-06-30 | [
[
"Pandey",
"Anjali",
""
],
[
"Kumar",
"Rajesh",
""
],
[
"Srivastava",
"Sudhir Kumar",
""
]
] | The present paper deals with the gravitational collapse of an inhomogeneous spherical star consisting of dust fluid in the background of dark energy components with linear equation of state. We discussed the development of apparent horizon to investigate the black-hole formation in gravitational collapsing process. The collapsing process is examined first separately for dust cloud and dark energy and then under the combined effect of dust interacting with dark energy. It is obtained that when only dust cloud or dark energy is present the collapse leads to the formation of black-hole under certain conditions. When both of them are present, collapsing star does not form black-hole. However when dark energy is considered as cosmological constant, the collapse leads to black hole formation. |
2305.15774 | Adri\`a G\'omez-Valent | Adri\`a G\'omez-Valent, Nick E. Mavromatos and Joan Sol\`a Peracaula | Stringy Running Vacuum Model and current Tensions in Cosmology | 38 pages, 6 figures, 7 tables. Version accepted for publication in
Classical and Quantum Gravity. Extended discussion (new section VII),
improved Figure 6, corrected typos and references added | null | 10.1088/1361-6382/ad0fb8 | null | gr-qc astro-ph.CO hep-ph hep-th | http://creativecommons.org/licenses/by/4.0/ | We discuss the potential alleviation of both the Hubble and the growth of
galactic structure data tensions observed in the current epoch of Cosmology in
the context of the so-called Stringy Running Vacuum Model (RVM) of Cosmology.
This is a gravitational field theory coupled to matter, which, at early eras,
contains gravitational (Chern-Simons (CS) type) anomalies and torsion, arising
from the fundamental degrees of freedom of the massless gravitational multiplet
of an underlying microscopic string theory. The model leads to RVM type
inflation without external inflatons, arising from the quartic powers of the
Hubble parameter that characterise the vacuum energy density due to
primordial-gravitational-wave-induced anomaly CS condensates, and dominate the
inflationary era. In modern eras, of relevance to this work, the gravitational
anomalies are cancelled by chiral matter, generated at the end of the RVM
inflationary era, but cosmic radiation and other matter fields are still
responsible for a RVM energy density with terms exhibiting a
quadratic-power-of-Hubble-parameter dependence, but also products of the latter
with logarithmic $H$-dependencies, arising from potential quantum-gravity and
quantum-matter loop effects. In this work, such terms are examined
phenomenologically from the point of view of the potential alleviation of the
aforementioned current tensions in Cosmology. Using standard information
criteria, we find that these tensions can be substantially alleviated in a way
consistent not only with the data, but also with the underlying microscopic
theory predictions, associated with the primordial dynamical breaking of
supergravity that characterise a pre-RVM-inflationary phase of the model.
| [
{
"created": "Thu, 25 May 2023 06:35:49 GMT",
"version": "v1"
},
{
"created": "Sun, 26 Nov 2023 09:21:38 GMT",
"version": "v2"
}
] | 2023-11-28 | [
[
"Gómez-Valent",
"Adrià",
""
],
[
"Mavromatos",
"Nick E.",
""
],
[
"Peracaula",
"Joan Solà",
""
]
] | We discuss the potential alleviation of both the Hubble and the growth of galactic structure data tensions observed in the current epoch of Cosmology in the context of the so-called Stringy Running Vacuum Model (RVM) of Cosmology. This is a gravitational field theory coupled to matter, which, at early eras, contains gravitational (Chern-Simons (CS) type) anomalies and torsion, arising from the fundamental degrees of freedom of the massless gravitational multiplet of an underlying microscopic string theory. The model leads to RVM type inflation without external inflatons, arising from the quartic powers of the Hubble parameter that characterise the vacuum energy density due to primordial-gravitational-wave-induced anomaly CS condensates, and dominate the inflationary era. In modern eras, of relevance to this work, the gravitational anomalies are cancelled by chiral matter, generated at the end of the RVM inflationary era, but cosmic radiation and other matter fields are still responsible for a RVM energy density with terms exhibiting a quadratic-power-of-Hubble-parameter dependence, but also products of the latter with logarithmic $H$-dependencies, arising from potential quantum-gravity and quantum-matter loop effects. In this work, such terms are examined phenomenologically from the point of view of the potential alleviation of the aforementioned current tensions in Cosmology. Using standard information criteria, we find that these tensions can be substantially alleviated in a way consistent not only with the data, but also with the underlying microscopic theory predictions, associated with the primordial dynamical breaking of supergravity that characterise a pre-RVM-inflationary phase of the model. |
2102.02707 | Ignacio Salazar | Nicol\'as Grandi and Ignacio Salazar Landea | Diving inside a hairy black hole | 22 pages, 7 figures, accepted to JHEP | J. High Energ. Phys. 2021, 152 (2021) | 10.1007/JHEP05(2021)152 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the interior of the Einstein-Gauss-Bonnet charged black-hole
with scalar hair. We find a variety of dynamical epochs, with the particular
important feature that the Cauchy horizon is not present. This makes the
violation of the no-hair theorem a possible tool to understand how might the
strong cosmic censorship conjecture work.
| [
{
"created": "Thu, 4 Feb 2021 16:02:10 GMT",
"version": "v1"
},
{
"created": "Tue, 25 May 2021 15:52:48 GMT",
"version": "v2"
}
] | 2021-05-26 | [
[
"Grandi",
"Nicolás",
""
],
[
"Landea",
"Ignacio Salazar",
""
]
] | We investigate the interior of the Einstein-Gauss-Bonnet charged black-hole with scalar hair. We find a variety of dynamical epochs, with the particular important feature that the Cauchy horizon is not present. This makes the violation of the no-hair theorem a possible tool to understand how might the strong cosmic censorship conjecture work. |
gr-qc/9711079 | Carsten Gundlach | Carsten Gundlach (Albert Einstein Institut, Potsdam) | Angular momentum at the black hole threshold | 4 pages, Revtex. Abbreviated version, using simpler notation | Phys.Rev.D57:7080-7083,1998 | 10.1103/PhysRevD.57.7080 | null | gr-qc | null | Near the black hole threshold in phase space, the black hole mass as a
function of the initial data shows the "critical scaling" M \simeq C
(p-p_*)^\gamma, where p labels a family of initial data, p_* is the value of p
at the threshold, and the critical exponent \gamma is universal for a given
matter model. The black hole charge Q obeys a similar law. To complete the
picture, we include angular momentum as a perturbation. For the black hole
angular momentum \vec L we find the oscillating behavior \vec L \simeq Re[
(\vec A + i \vec B) (p-p_*)^{\mu+i\omega} ]. The assumptions of the calculation
hold for p = \rho / 3 perfect fluid matter, and we calculate \mu \simeq 0.799
and \omega \simeq 0.231.
| [
{
"created": "Wed, 26 Nov 1997 14:38:52 GMT",
"version": "v1"
},
{
"created": "Sun, 21 Dec 1997 17:33:23 GMT",
"version": "v2"
}
] | 2009-12-30 | [
[
"Gundlach",
"Carsten",
"",
"Albert Einstein Institut, Potsdam"
]
] | Near the black hole threshold in phase space, the black hole mass as a function of the initial data shows the "critical scaling" M \simeq C (p-p_*)^\gamma, where p labels a family of initial data, p_* is the value of p at the threshold, and the critical exponent \gamma is universal for a given matter model. The black hole charge Q obeys a similar law. To complete the picture, we include angular momentum as a perturbation. For the black hole angular momentum \vec L we find the oscillating behavior \vec L \simeq Re[ (\vec A + i \vec B) (p-p_*)^{\mu+i\omega} ]. The assumptions of the calculation hold for p = \rho / 3 perfect fluid matter, and we calculate \mu \simeq 0.799 and \omega \simeq 0.231. |
1109.0840 | Keiichi Akama | Keiichi Akama, Takashi Hattori, Hisamitsu Mukaida | General Solution for the Static, Spherical and Asymptotically Flat
Braneworld | 5 pages, no figure, submitted to the Japanese Physical Society 2011
Annual Meeting which was canceled due to the earthquake in Tohoku district in
March, with errors corrected, and with the sign convention of the curvature
tensor changed | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The general solution for the static, spherical and asymptotically flat
braneworld is derived by solving the bulk Einstein equation and braneworld
dynamics. We show that it involves a large arbitrariness, which reduces the
predictability of the theory. Ways out of the difficulty are discussed.
| [
{
"created": "Mon, 5 Sep 2011 09:44:44 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Sep 2011 10:06:26 GMT",
"version": "v2"
},
{
"created": "Thu, 26 Jul 2012 13:23:55 GMT",
"version": "v3"
}
] | 2012-07-27 | [
[
"Akama",
"Keiichi",
""
],
[
"Hattori",
"Takashi",
""
],
[
"Mukaida",
"Hisamitsu",
""
]
] | The general solution for the static, spherical and asymptotically flat braneworld is derived by solving the bulk Einstein equation and braneworld dynamics. We show that it involves a large arbitrariness, which reduces the predictability of the theory. Ways out of the difficulty are discussed. |
0709.0819 | G. Papini | Giorgio Papini | Spin-gravity coupling and gravity-induced quantum phases | 18 pages, 1 figure | null | 10.1007/s10714-007-0595-z | null | gr-qc | null | External gravitational fields induce phase factors in the wave functions of
particles. The phases are exact to first order in the background gravitational
field, are manifestly covariant and gauge invariant and provide a useful tool
for the study of spin-gravity coupling and of the optics of particles in
gravitational or inertial fields. We discuss the role that spin-gravity
coupling plays in particular problems.
| [
{
"created": "Thu, 6 Sep 2007 10:15:57 GMT",
"version": "v1"
}
] | 2009-11-13 | [
[
"Papini",
"Giorgio",
""
]
] | External gravitational fields induce phase factors in the wave functions of particles. The phases are exact to first order in the background gravitational field, are manifestly covariant and gauge invariant and provide a useful tool for the study of spin-gravity coupling and of the optics of particles in gravitational or inertial fields. We discuss the role that spin-gravity coupling plays in particular problems. |
gr-qc/9801033 | George Tsoupros | George Tsoupros | Scaling Behaviour of Conformal Fields in Curved Three-dimensional Space | 12p. Latex, One reference added, To appear in Physics Letters B | Phys.Lett. B423 (1998) 225-230 | 10.1016/S0370-2693(98)00085-9 | ISSN 1038-751X | gr-qc | null | The limitations of three-dimensional semi-classical gravity are explored in
the context of a conformally invariant theory for a self-interacting scalar
field. The analysis of the theory's scaling behaviour reveals that scalar-loop
effects contribute to the conformal anomaly only at advanced orders allowing
for a range of relevant energy scales which extend to those comparable to the
non-perturbative scale of Planck mass.
| [
{
"created": "Mon, 12 Jan 1998 05:26:46 GMT",
"version": "v1"
},
{
"created": "Thu, 15 Jan 1998 05:17:54 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Tsoupros",
"George",
""
]
] | The limitations of three-dimensional semi-classical gravity are explored in the context of a conformally invariant theory for a self-interacting scalar field. The analysis of the theory's scaling behaviour reveals that scalar-loop effects contribute to the conformal anomaly only at advanced orders allowing for a range of relevant energy scales which extend to those comparable to the non-perturbative scale of Planck mass. |
gr-qc/0105092 | Ryo Yamazaki | Ryo Yamazaki, Daisuke Ida (Kyoto University) | Black holes in three-dimensional Einstein-Born-Infeld-dilaton theory | 10 pages LaTeX, 2 eps figures, accepted for publication in PRD | Phys.Rev. D64 (2001) 024009 | 10.1103/PhysRevD.64.024009 | null | gr-qc | null | The three-dimensional static and circularly symmetric solution of the
Einstein-Born-Infeld-dilaton system is derived. The solutions corresponding to
low energy string theory are investigated in detail, which include black hole
solutions if the cosmological constant is negative and the mass parameter
exceeds a certain critical value. Some differences between the Born-Infeld
nonlinear electrodynamics and the Maxwell electrodynamics are revealed.
| [
{
"created": "Fri, 25 May 2001 08:28:01 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Yamazaki",
"Ryo",
"",
"Kyoto University"
],
[
"Ida",
"Daisuke",
"",
"Kyoto University"
]
] | The three-dimensional static and circularly symmetric solution of the Einstein-Born-Infeld-dilaton system is derived. The solutions corresponding to low energy string theory are investigated in detail, which include black hole solutions if the cosmological constant is negative and the mass parameter exceeds a certain critical value. Some differences between the Born-Infeld nonlinear electrodynamics and the Maxwell electrodynamics are revealed. |
2403.17619 | Da Huang | Yuan-Kun Gao, Da Huang, Yong-Liang Ma, Yong Tang, Yue-Liang Wu,
Yu-Feng Zhou | Linear dynamics and classical tests of the gravitational quantum field
theory | 7 pages, 1 figure | Phys. Rev. D 109, 064072(2024) | 10.1103/PhysRevD.109.064072 | null | gr-qc hep-ph hep-th | http://creativecommons.org/licenses/by/4.0/ | We explore the new physics phenomena of gravidynamics governed by the
inhomogeneous spin gauge symmetry based on the gravitational quantum field
theory. Such a gravidynamics enables us to derive the generalized Einstein
equation and an equation beyond it. To simplify the analyses, we linearize the
dynamic equations of gravitational interaction by keeping terms up to the
leading order in the dual gravigauge field. We then apply the linearized
dynamic equations into two particular gravitational phenomena. First, we
consider the linearized equations in the absence of source fields, which is
shown to have five physical propagating polarizations as gravitational waves,
i.e., two tensor modes, two vector modes, and one scalar, instead of two tensor
polarizations in the general relativity. Second, we examine the Newtonian limit
in which the gravitational fields and the matter source distribution are weak
and static. By deriving the associated Poisson equation, we obtain the exact
relation of the fundamental interaction coupling in the gravidynamics with the
experimentally measured Newtonian constant. We also make use of nonrelativistic
objects and relativistic photons to probe the Newtonian field configurations.
In particular, the experiments from the gravitational deflection of light rays
and the Shapiro time delay can place stringent constraints on the linearized
gravidynamics in the gravitational quantum field theory.
| [
{
"created": "Tue, 26 Mar 2024 11:50:27 GMT",
"version": "v1"
}
] | 2024-03-27 | [
[
"Gao",
"Yuan-Kun",
""
],
[
"Huang",
"Da",
""
],
[
"Ma",
"Yong-Liang",
""
],
[
"Tang",
"Yong",
""
],
[
"Wu",
"Yue-Liang",
""
],
[
"Zhou",
"Yu-Feng",
""
]
] | We explore the new physics phenomena of gravidynamics governed by the inhomogeneous spin gauge symmetry based on the gravitational quantum field theory. Such a gravidynamics enables us to derive the generalized Einstein equation and an equation beyond it. To simplify the analyses, we linearize the dynamic equations of gravitational interaction by keeping terms up to the leading order in the dual gravigauge field. We then apply the linearized dynamic equations into two particular gravitational phenomena. First, we consider the linearized equations in the absence of source fields, which is shown to have five physical propagating polarizations as gravitational waves, i.e., two tensor modes, two vector modes, and one scalar, instead of two tensor polarizations in the general relativity. Second, we examine the Newtonian limit in which the gravitational fields and the matter source distribution are weak and static. By deriving the associated Poisson equation, we obtain the exact relation of the fundamental interaction coupling in the gravidynamics with the experimentally measured Newtonian constant. We also make use of nonrelativistic objects and relativistic photons to probe the Newtonian field configurations. In particular, the experiments from the gravitational deflection of light rays and the Shapiro time delay can place stringent constraints on the linearized gravidynamics in the gravitational quantum field theory. |
gr-qc/0601081 | Alicia M. Sintes | Alicia M. Sintes and Badri Krishnan | Improved Hough search for gravitational wave pulsars | 6 pages, Accepted in Journal of Physics: Conference Series | J.Phys.Conf.Ser. 32 (2006) 206-211 | 10.1088/1742-6596/32/1/031 | null | gr-qc | null | We describe an improved version of the Hough transform search for continuous
gravitational waves from isolated neutron stars assuming the input to be short
segments of Fourier transformed data. The method presented here takes into
account possible non-stationarities of the detector noise and the amplitude
modulation due to the motion of the detector. These two effects are taken into
account for the first stage only, i.e. the peak selection, to create the
time-frequency map of our data, while the Hough transform itself is performed
in the standard way.
| [
{
"created": "Thu, 19 Jan 2006 17:57:36 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Sintes",
"Alicia M.",
""
],
[
"Krishnan",
"Badri",
""
]
] | We describe an improved version of the Hough transform search for continuous gravitational waves from isolated neutron stars assuming the input to be short segments of Fourier transformed data. The method presented here takes into account possible non-stationarities of the detector noise and the amplitude modulation due to the motion of the detector. These two effects are taken into account for the first stage only, i.e. the peak selection, to create the time-frequency map of our data, while the Hough transform itself is performed in the standard way. |
2102.04795 | Jie Zhang | Jie Zhang, Menquan Liu, Zhie Liu and Shuzheng Yang | An Improvement for Quantum Tunneling Radiation of Fermions in a
Stationary Kerr-Newman Black Hole Spacetime | null | null | 10.1016/j.cjph.2022.08.009 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | By introducing a specific etheric-like vector in the Dirac equation with
Lorentz Invariance Violation (LIV) in the curved spacetime, an improved method
for quantum tunneling radiation of fermions is proposed. As an example, we
apply this new method to a charged axisymmetric Kerr-Newman black hole.
Firstly, considering LIV theory, we derive a modified dynamical equation of
fermion with spin 1/2 in the Kerr-Newman black hole spacetime. Then we solve
the equation and find the increase or decrease of black hole's Hawking
temperature and entropy are related to constants $a$ and $c$ of the Dirac
equation with LIV in the curved spacetime. As $c$ is positive, the new Hawking
temperature is about $ \frac{\sqrt{1+2a+2cmk_r^2}}{\sqrt{1+2a}}$ times higher
than that without modification, but the entropy will decrease. We also make a
brief discussion for the case of high spin fermions.
| [
{
"created": "Tue, 9 Feb 2021 12:30:32 GMT",
"version": "v1"
}
] | 2022-10-12 | [
[
"Zhang",
"Jie",
""
],
[
"Liu",
"Menquan",
""
],
[
"Liu",
"Zhie",
""
],
[
"Yang",
"Shuzheng",
""
]
] | By introducing a specific etheric-like vector in the Dirac equation with Lorentz Invariance Violation (LIV) in the curved spacetime, an improved method for quantum tunneling radiation of fermions is proposed. As an example, we apply this new method to a charged axisymmetric Kerr-Newman black hole. Firstly, considering LIV theory, we derive a modified dynamical equation of fermion with spin 1/2 in the Kerr-Newman black hole spacetime. Then we solve the equation and find the increase or decrease of black hole's Hawking temperature and entropy are related to constants $a$ and $c$ of the Dirac equation with LIV in the curved spacetime. As $c$ is positive, the new Hawking temperature is about $ \frac{\sqrt{1+2a+2cmk_r^2}}{\sqrt{1+2a}}$ times higher than that without modification, but the entropy will decrease. We also make a brief discussion for the case of high spin fermions. |
gr-qc/9807080 | Vladimir Dzhunushaliev | V.Dzhunushaliev | Multidimensional Geometrical Model of the Renormalized Electrical Charge
with Splitting off the Extra Coordinates | 10 pages, 1 figure, awarded Honorable Mention by Grav.Res.Found.,
1998 | Mod.Phys.Lett. A13 (1998) 2179-2186 | 10.1142/S021773239800231X | null | gr-qc | null | A geometrical model of electric charge is proposed. This model has ``naked''
charge screened with a ``fur - coat'' consisting of virtual wormholes. The 5D
wormhole solution in the Kaluza - Klein theory is the ``naked'' charge. The
splitting off of the 5D dimension happens on the two spheres (null surfaces)
bounding this 5D wormhole. This allows one to sew two Reissner - Nordstr\"om
black holes onto it on both sides. The virtual wormholes entrap a part of the
electrical flux lines coming into the ``naked'' charge. This effect essentially
changes the charge visible at infinity so that it satisfies the real relation
$m^2<e^2$.
| [
{
"created": "Wed, 29 Jul 1998 13:47:10 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Dzhunushaliev",
"V.",
""
]
] | A geometrical model of electric charge is proposed. This model has ``naked'' charge screened with a ``fur - coat'' consisting of virtual wormholes. The 5D wormhole solution in the Kaluza - Klein theory is the ``naked'' charge. The splitting off of the 5D dimension happens on the two spheres (null surfaces) bounding this 5D wormhole. This allows one to sew two Reissner - Nordstr\"om black holes onto it on both sides. The virtual wormholes entrap a part of the electrical flux lines coming into the ``naked'' charge. This effect essentially changes the charge visible at infinity so that it satisfies the real relation $m^2<e^2$. |
1908.10617 | Dmitri Gal'tsov | Gerard Cl\'ement and Dmitri Gal'tsov | On the Smarr formulas for electrovac spacetimes with line singularities | 15 pages Latex2e | Phys. Lett. B 802 (2020) 135270 | 10.1016/j.physletb.2020.135270 | LAPTH-043/19 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using the revised Komar-Tomimatsu approach, we derive Smarr mass formulas for
stationary axisymmetric solutions of the Einstein-Maxwell equations containing
line singularities (defects) on the polar axis. In terms of the rod structure
associated with Weyl representation of the metric, the horizons and the defects
are formally similar up to differences due to their timelike/spacelike
character. We derive (previously unknown or incorrect) horizon and global Smarr
formulas in presence of a Newman-Unti-Tamburino (NUT) parameter. To avoid the
divergence of the Komar angular momentum of semi-infinite Dirac and Misner
strings, it is necessary to use a symmetric tuning. We also note that the
horizon mass Smarr formula does not include either magnetic charge, or NUT
parameter, correcting some statements in the literature. The contribution of
each Misner string to the total mass consists in an angular momentum term, an
electric charge term, and a length term, which can also be presented as the
product of the spacelike analogue of surface gravity and the area of the
string.
| [
{
"created": "Wed, 28 Aug 2019 09:54:55 GMT",
"version": "v1"
}
] | 2021-03-01 | [
[
"Clément",
"Gerard",
""
],
[
"Gal'tsov",
"Dmitri",
""
]
] | Using the revised Komar-Tomimatsu approach, we derive Smarr mass formulas for stationary axisymmetric solutions of the Einstein-Maxwell equations containing line singularities (defects) on the polar axis. In terms of the rod structure associated with Weyl representation of the metric, the horizons and the defects are formally similar up to differences due to their timelike/spacelike character. We derive (previously unknown or incorrect) horizon and global Smarr formulas in presence of a Newman-Unti-Tamburino (NUT) parameter. To avoid the divergence of the Komar angular momentum of semi-infinite Dirac and Misner strings, it is necessary to use a symmetric tuning. We also note that the horizon mass Smarr formula does not include either magnetic charge, or NUT parameter, correcting some statements in the literature. The contribution of each Misner string to the total mass consists in an angular momentum term, an electric charge term, and a length term, which can also be presented as the product of the spacelike analogue of surface gravity and the area of the string. |
1310.6230 | Michele Sciacca | David Jou, Maria Stella Mongiovi', Michele Sciacca | A duality-invariant Einstein-Planck relation and its consequences on
micro black holes | null | International Journal of Modern Physics D Vol. 23, No. 2 (2014)
1450018 (9 pages) | 10.1142/S0218271814500187 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss the consequences of a duality-invariant Einstein-Planck relation
on the equation of state of micro black holes. The results are analogous to
those obtained from the "world crystal" model, but with some significative
differences, as for instance a limiting vanishing value for temperature for
very small black holes. The model leads to a total evaporation of micro black
holes but with the final stage being very slow.
| [
{
"created": "Wed, 23 Oct 2013 14:04:40 GMT",
"version": "v1"
}
] | 2014-05-14 | [
[
"Jou",
"David",
""
],
[
"Mongiovi'",
"Maria Stella",
""
],
[
"Sciacca",
"Michele",
""
]
] | We discuss the consequences of a duality-invariant Einstein-Planck relation on the equation of state of micro black holes. The results are analogous to those obtained from the "world crystal" model, but with some significative differences, as for instance a limiting vanishing value for temperature for very small black holes. The model leads to a total evaporation of micro black holes but with the final stage being very slow. |
1811.09086 | Ioannis Contopoulos | Demetrios Papadopoulos and Ioannis Contopoulos | The magnetic Rayleigh-Taylor instability around astrophysical black
holes | 11 pages, 1 figure, accepted for publication in Monthly Notices | null | 10.1093/mnras/sty3167 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the development of the magnetic Rayleigh-Taylor instability at
the inner edge of an astrophysical disk around a spinning central black hole.
We solve the equations of general relativity that govern small amplitude
oscillations of a discontinuous interface in a Keplerian disk threaded by an
ordered magnetic field, and we derive a stability criterion that depends on the
central black hole spin and the accumulated magnetic field. We also compare our
results with the results of GR MHD simulations of black hole accretion flows
that reach a magnetically arrested state (MAD). We found that the instability
growth timescales that correspond to the simulation parameters are comparable
to the corresponding timescales for free-fall accretion from the ISCO onto the
black hole. We thus propose that the Rayleigh-Taylor instability disrupts the
accumulation of magnetic flux onto the black hole horizon as the disk reaches a
MAD state.
| [
{
"created": "Thu, 22 Nov 2018 10:25:33 GMT",
"version": "v1"
}
] | 2018-12-26 | [
[
"Papadopoulos",
"Demetrios",
""
],
[
"Contopoulos",
"Ioannis",
""
]
] | We investigate the development of the magnetic Rayleigh-Taylor instability at the inner edge of an astrophysical disk around a spinning central black hole. We solve the equations of general relativity that govern small amplitude oscillations of a discontinuous interface in a Keplerian disk threaded by an ordered magnetic field, and we derive a stability criterion that depends on the central black hole spin and the accumulated magnetic field. We also compare our results with the results of GR MHD simulations of black hole accretion flows that reach a magnetically arrested state (MAD). We found that the instability growth timescales that correspond to the simulation parameters are comparable to the corresponding timescales for free-fall accretion from the ISCO onto the black hole. We thus propose that the Rayleigh-Taylor instability disrupts the accumulation of magnetic flux onto the black hole horizon as the disk reaches a MAD state. |
1201.3028 | Hyeyoun Chung | Hyeyoun Chung | Tunneling between single and multi-centered black hole configurations | 8 pages, 4 figures. v4: final version accepted for publication in
Phys. Rev. D | null | 10.1103/PhysRevD.86.064036 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We find a gravitational instanton that connects an initial state
corresponding to a single-centered extremal Reissner-Nordstrom (ERN) black hole
configuration, to a final state corresponding to a multi-centered
configuration. This instanton is interpreted as describing quantum tunneling
between the two different black hole solutions. We evaluate the Euclidean
action for this instanton and find that the amplitude for the tunneling process
is equal to half the difference in entropy between the initial and final
configurations.
| [
{
"created": "Sat, 14 Jan 2012 17:06:05 GMT",
"version": "v1"
},
{
"created": "Thu, 19 Jan 2012 14:00:07 GMT",
"version": "v2"
},
{
"created": "Thu, 15 Mar 2012 19:55:39 GMT",
"version": "v3"
},
{
"created": "Mon, 20 Aug 2012 17:22:47 GMT",
"version": "v4"
}
] | 2013-05-30 | [
[
"Chung",
"Hyeyoun",
""
]
] | We find a gravitational instanton that connects an initial state corresponding to a single-centered extremal Reissner-Nordstrom (ERN) black hole configuration, to a final state corresponding to a multi-centered configuration. This instanton is interpreted as describing quantum tunneling between the two different black hole solutions. We evaluate the Euclidean action for this instanton and find that the amplitude for the tunneling process is equal to half the difference in entropy between the initial and final configurations. |
gr-qc/0606061 | T. Padmanabhan | T. Padmanabhan | Gravity: A New Holographic Perspective | Plenary talk at the International Conference on Einstein's Legacy in
the New Millennium, December 15 - 22, 2005, Puri, India; to appear in the
Proceedings to be published in IJMPD; 16 pages; no figures | Int.J.Mod.Phys. D15 (2006) 1659-1676 | 10.1142/S0218271806009029 | null | gr-qc astro-ph hep-th | null | A general paradigm for describing classical (and semiclassical) gravity is
presented. This approach brings to the centre-stage a holographic relationship
between the bulk and surface terms in a general class of action functionals and
provides a deeper insight into several aspects of classical gravity which have
no explanation in the conventional approach. After highlighting a series of
unresolved issues in the conventional approach to gravity, I show that (i)
principle of equivalence, (ii) general covariance and (iii)a reasonable
condition on the variation of the action functional, suggest a generic
Lagrangian for semiclassical gravity of the form $L=Q_a^{bcd}R^a_{bcd}$ with
$\nabla_b Q_a^{bcd}=0$. The expansion of $Q_a^{bcd}$ in terms of the
derivatives of the metric tensor determines the structure of the theory
uniquely. The zeroth order term gives the Einstein-Hilbert action and the first
order correction is given by the Gauss-Bonnet action. Any such Lagrangian can
be decomposed into a surface and bulk terms which are related holographically.
The equations of motion can be obtained purely from a surface term in the
gravity sector. Hence the field equations are invariant under the
transformation $T_{ab} \to T_{ab} + \lambda g_{ab}$ and gravity does not
respond to the changes in the bulk vacuum energy density. The cosmological
constant arises as an integration constant in this approach. The implications
are discussed.
| [
{
"created": "Wed, 14 Jun 2006 12:43:44 GMT",
"version": "v1"
},
{
"created": "Tue, 27 Jun 2006 18:13:20 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Padmanabhan",
"T.",
""
]
] | A general paradigm for describing classical (and semiclassical) gravity is presented. This approach brings to the centre-stage a holographic relationship between the bulk and surface terms in a general class of action functionals and provides a deeper insight into several aspects of classical gravity which have no explanation in the conventional approach. After highlighting a series of unresolved issues in the conventional approach to gravity, I show that (i) principle of equivalence, (ii) general covariance and (iii)a reasonable condition on the variation of the action functional, suggest a generic Lagrangian for semiclassical gravity of the form $L=Q_a^{bcd}R^a_{bcd}$ with $\nabla_b Q_a^{bcd}=0$. The expansion of $Q_a^{bcd}$ in terms of the derivatives of the metric tensor determines the structure of the theory uniquely. The zeroth order term gives the Einstein-Hilbert action and the first order correction is given by the Gauss-Bonnet action. Any such Lagrangian can be decomposed into a surface and bulk terms which are related holographically. The equations of motion can be obtained purely from a surface term in the gravity sector. Hence the field equations are invariant under the transformation $T_{ab} \to T_{ab} + \lambda g_{ab}$ and gravity does not respond to the changes in the bulk vacuum energy density. The cosmological constant arises as an integration constant in this approach. The implications are discussed. |
gr-qc/0201048 | Raimundo Silva Junior | R. Silva (UFRN), J. A. S. Lima (UFRN), and M. O. Calv\~ao (UFRJ) | Temperature Evolution Law of Imperfect Relativistic Fluids | 14 pages, no figure, revtex | Gen.Rel.Grav.34:865-875,2002 | 10.1023/A:1016317914912 | null | gr-qc | null | The first-order general relativistic theory of a generic dissipative
(heat-conducting, viscous, particle-creating) fluid is rediscussed from a
unified covariant frame-independent point of view. By generalizing some
previous works in the literature, we derive a formula for the temperature
variation rate, which is valid both in Eckart's (particle) and in the
Landau-Lifshitz (energy) frames. Particular attention is paid to the case of
gravitational particle creation and its possible cross-effect with the bulk
viscosity mechanism.
| [
{
"created": "Mon, 14 Jan 2002 23:30:29 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Silva",
"R.",
"",
"UFRN"
],
[
"Lima",
"J. A. S.",
"",
"UFRN"
],
[
"Calvão",
"M. O.",
"",
"UFRJ"
]
] | The first-order general relativistic theory of a generic dissipative (heat-conducting, viscous, particle-creating) fluid is rediscussed from a unified covariant frame-independent point of view. By generalizing some previous works in the literature, we derive a formula for the temperature variation rate, which is valid both in Eckart's (particle) and in the Landau-Lifshitz (energy) frames. Particular attention is paid to the case of gravitational particle creation and its possible cross-effect with the bulk viscosity mechanism. |
1201.0061 | Seyed Hossein Hendi | S. H. Hendi and D. Momeni | Black hole solutions in F(R) gravity with conformal anomaly | 12 pages, one figure | Eur. Phys. J. C 71 (2011) 1823 | 10.1140/epjc/s10052-011-1823-y | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we consider $F(R)=R+f(R)$ theory instead of Einstein gravity
with conformal anomaly and look for its analytical solutions. Depending on the
free parameters, one may obtain both uncharged and charged solutions for some
classes of $F(R)$ models. Calculation of Kretschmann scalar shows that there is
a singularity located at $r=0$, which the geometry of uncharged (charged)
solution is corresponding to the Schwarzschild (Reissner-Nordstr\"om)
singularity. Further, we discuss the viability of our models in details. We
show that these models can be stable depending on their parameters and in
different epoches of the universe.
| [
{
"created": "Fri, 30 Dec 2011 04:30:29 GMT",
"version": "v1"
}
] | 2012-01-04 | [
[
"Hendi",
"S. H.",
""
],
[
"Momeni",
"D.",
""
]
] | In this paper, we consider $F(R)=R+f(R)$ theory instead of Einstein gravity with conformal anomaly and look for its analytical solutions. Depending on the free parameters, one may obtain both uncharged and charged solutions for some classes of $F(R)$ models. Calculation of Kretschmann scalar shows that there is a singularity located at $r=0$, which the geometry of uncharged (charged) solution is corresponding to the Schwarzschild (Reissner-Nordstr\"om) singularity. Further, we discuss the viability of our models in details. We show that these models can be stable depending on their parameters and in different epoches of the universe. |
2402.08704 | Behzad Eslam Panah | Kh. Jafarzade, B. Eslam Panah, and M. E. Rodrigues | Thermodynamics and Optical Properties of Phantom AdS Black Holes in
Massive Gravity | 26 pages, 12 figures, 1 table | Class. Quantum Grav. 41 (2024) 065007 | 10.1088/1361-6382/ad242e | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Motivated by high interest in Lorentz invariant massive gravity models known
as dRGT massive gravity, we present an exact phantom black hole solution in
this theory of gravity and discuss the thermodynamic structure of the black
hole in the canonical ensemble. Calculating the conserved and thermodynamic
quantities, we check the validity of the first law of thermodynamics and the
Smarr relation in the extended phase space. In addition, we investigate both
the local and global stability of these black holes and show how massive
parameters affect the regions of stability. We extend our study to investigate
the optical features of the black holes such as the shadow geometrical shape,
energy emission rate, and deflection angle. Also, we discuss how these optical
quantities are affected by massive coefficients. Finally, we consider a massive
scalar perturbation minimally coupled to the background geometry of the black
hole and examine the quasinormal modes (QNMs) by employing the WKB
approximation.
| [
{
"created": "Tue, 13 Feb 2024 17:10:49 GMT",
"version": "v1"
}
] | 2024-02-15 | [
[
"Jafarzade",
"Kh.",
""
],
[
"Panah",
"B. Eslam",
""
],
[
"Rodrigues",
"M. E.",
""
]
] | Motivated by high interest in Lorentz invariant massive gravity models known as dRGT massive gravity, we present an exact phantom black hole solution in this theory of gravity and discuss the thermodynamic structure of the black hole in the canonical ensemble. Calculating the conserved and thermodynamic quantities, we check the validity of the first law of thermodynamics and the Smarr relation in the extended phase space. In addition, we investigate both the local and global stability of these black holes and show how massive parameters affect the regions of stability. We extend our study to investigate the optical features of the black holes such as the shadow geometrical shape, energy emission rate, and deflection angle. Also, we discuss how these optical quantities are affected by massive coefficients. Finally, we consider a massive scalar perturbation minimally coupled to the background geometry of the black hole and examine the quasinormal modes (QNMs) by employing the WKB approximation. |
1902.01397 | Ujjal Debnath | Ujjal Debnath and Kazuharu Bamba | Parametrizations of Dark Energy Models in the Background of General
Non-canonical Scalar Field in $D$-dimensional Fractal Universe | 19 pages, 32 figures, Accepted for publication in Eur. Phys. J. C | null | 10.1140/epjc/s10052-019-7172-y | FU-PCG-54 | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We explore non-canonical scalar field model in the background of non-flat
$D$-dimensional fractal Universe with cosmological constant $\Lambda$ on the
condition that the matter and scalar field are separately conserved. The
potential $V$, scalar field $\phi$, function $f$, densities, Hubble parameter
and deceleration parameter can be expressed in terms of the redshift $z$ and
these depend on the equation of state parameter $w_{\phi}$. We also investigate
four kinds of well known parametrization models and graphically we have
analyzed the natures of potential, scalar field, function $f$, densities, the
Hubble parameter and deceleration parameter. As a result, the best fitted
values of the unknown parameters ($w_{0},w_{1}$) of the parametrizations models
due to the joint data analysis (SNIa+BAO+CMB+Hubble) are found. Furthermore,
the minimum values of $\chi^{2}$ function are obtained. Also we have plotted
the graphs for different confidence levels 66\%, 90\% and 99\% contours for
($w_{0},~w_{1}$) by fixing the other parameters.
| [
{
"created": "Mon, 4 Feb 2019 17:10:33 GMT",
"version": "v1"
},
{
"created": "Fri, 26 Jul 2019 13:14:29 GMT",
"version": "v2"
}
] | 2019-10-02 | [
[
"Debnath",
"Ujjal",
""
],
[
"Bamba",
"Kazuharu",
""
]
] | We explore non-canonical scalar field model in the background of non-flat $D$-dimensional fractal Universe with cosmological constant $\Lambda$ on the condition that the matter and scalar field are separately conserved. The potential $V$, scalar field $\phi$, function $f$, densities, Hubble parameter and deceleration parameter can be expressed in terms of the redshift $z$ and these depend on the equation of state parameter $w_{\phi}$. We also investigate four kinds of well known parametrization models and graphically we have analyzed the natures of potential, scalar field, function $f$, densities, the Hubble parameter and deceleration parameter. As a result, the best fitted values of the unknown parameters ($w_{0},w_{1}$) of the parametrizations models due to the joint data analysis (SNIa+BAO+CMB+Hubble) are found. Furthermore, the minimum values of $\chi^{2}$ function are obtained. Also we have plotted the graphs for different confidence levels 66\%, 90\% and 99\% contours for ($w_{0},~w_{1}$) by fixing the other parameters. |
2206.14043 | Orlando Luongo | Roberto Giamb\`o, Orlando Luongo, Lorenza Mauro | Red and blue shift in spherical and axisymmetric spacetimes and
astrophysical constraints | 18 pages, 6 figures, 9 tables | The Eur. Phys. J. Plus, 137, 612, (2022) | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compute the red and blue shifts for astrophysical and cosmological
sources. In particular, we consider low, intermediate and high gravitational
energy domains. Thereby, we handle the binary system Earth - Mars as low energy
landscape whereas white dwarfs and neutron stars as higher energy sources. To
this end, we take into account a spherical Schwarzschild - de Sitter spacetime
and an axially symmetric Zipoy - Voorhees metric to model all the
aforementioned systems. Feasible outcomes come from modelling neutron stars and
white dwarfs with the Zipoy - Voorhees metric, where quadrupole effects are
relevant, and framing solar system objects using a Schwarzschild - de Sitter
spacetime. In the first case, large $\delta$ parameters seem to be favorite,
leading to acceptable bounds mainly for neutron stars. In the second case, we
demonstrate incompatible red and blue shifts with respect to lunar and
satellite laser ranging expectations, once the cosmological constant is taken
to Planck satellite's best fit. To heal this issue, we suggest coarse-grained
experimental setups and propose Phobos for working out satellite laser ranging
in order to get more suitable red and blue shift intervals, possibly more
compatible than current experimental bounds. Implications to cosmological
tensions are also debated.
| [
{
"created": "Tue, 28 Jun 2022 14:41:05 GMT",
"version": "v1"
}
] | 2022-06-29 | [
[
"Giambò",
"Roberto",
""
],
[
"Luongo",
"Orlando",
""
],
[
"Mauro",
"Lorenza",
""
]
] | We compute the red and blue shifts for astrophysical and cosmological sources. In particular, we consider low, intermediate and high gravitational energy domains. Thereby, we handle the binary system Earth - Mars as low energy landscape whereas white dwarfs and neutron stars as higher energy sources. To this end, we take into account a spherical Schwarzschild - de Sitter spacetime and an axially symmetric Zipoy - Voorhees metric to model all the aforementioned systems. Feasible outcomes come from modelling neutron stars and white dwarfs with the Zipoy - Voorhees metric, where quadrupole effects are relevant, and framing solar system objects using a Schwarzschild - de Sitter spacetime. In the first case, large $\delta$ parameters seem to be favorite, leading to acceptable bounds mainly for neutron stars. In the second case, we demonstrate incompatible red and blue shifts with respect to lunar and satellite laser ranging expectations, once the cosmological constant is taken to Planck satellite's best fit. To heal this issue, we suggest coarse-grained experimental setups and propose Phobos for working out satellite laser ranging in order to get more suitable red and blue shift intervals, possibly more compatible than current experimental bounds. Implications to cosmological tensions are also debated. |
1405.6102 | Jacek Tafel | Jacek Tafel | On the energy of a null cone | 8 pages | Class. Quantum Grav. 31 (2014) 235011 | 10.1088/0264-9381/31/23/235011 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive a formula for the Bondi mass aspect in terms of asymptotic data of
the Bondi-Sachs metric in the affine gauge. We prove the positivity of the
total energy of a regular null cone in agreement with a recent result of
Chru\'{s}ciel and Paetz.
| [
{
"created": "Fri, 23 May 2014 15:45:38 GMT",
"version": "v1"
},
{
"created": "Tue, 27 May 2014 20:44:25 GMT",
"version": "v2"
},
{
"created": "Tue, 3 Feb 2015 09:55:10 GMT",
"version": "v3"
}
] | 2016-02-12 | [
[
"Tafel",
"Jacek",
""
]
] | We derive a formula for the Bondi mass aspect in terms of asymptotic data of the Bondi-Sachs metric in the affine gauge. We prove the positivity of the total energy of a regular null cone in agreement with a recent result of Chru\'{s}ciel and Paetz. |
gr-qc/9602004 | Jack Wells | I.B. Khriplovich, A.A. Pomeransky | Gravitational Interaction of Spinning Bodies, Center-of-Mass Coordinate
and Radiation of Compact Binary Systems | 11 pages, latex, no figures | Phys.Lett. A216 (1996) 7 | 10.1016/0375-9601(96)00266-6 | BINP 96-3 | gr-qc | null | Spin-orbit and spin-spin effects in the gravitational interaction are treated
in a close analogy with the fine and hyperfine interactions in atoms. The
proper definition of the cener-of-mass coordinate is discussed. The technique
developed is applied then to the gravitational radiation of compact binary
stars. Our result for the spin-orbit correction differs from that obtained by
other authors. New effects possible for the motion of a spinning particle in a
gravitational field are pointed out. The corresponding corrections, nonlinear
in spin, are in principle of the same order of magnitude as the ordinary
spin-spin interaction.
| [
{
"created": "Thu, 1 Feb 1996 21:50:06 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Khriplovich",
"I. B.",
""
],
[
"Pomeransky",
"A. A.",
""
]
] | Spin-orbit and spin-spin effects in the gravitational interaction are treated in a close analogy with the fine and hyperfine interactions in atoms. The proper definition of the cener-of-mass coordinate is discussed. The technique developed is applied then to the gravitational radiation of compact binary stars. Our result for the spin-orbit correction differs from that obtained by other authors. New effects possible for the motion of a spinning particle in a gravitational field are pointed out. The corresponding corrections, nonlinear in spin, are in principle of the same order of magnitude as the ordinary spin-spin interaction. |
1408.5885 | Genly Le\'on | Gustavo Pulgar (Valparaiso U., Catolica), Joel Saavedra (Valparaiso
U., Catolica), Genly Leon (Valparaiso U., Catolica) and Yoelsy Leyva
(Tarapaca U.) | Higher Order Lagrangians inspired by the Pais-Uhlenbeck Oscillator and
their cosmological applications | 30 pages, 7 figures. Affiliations updated. References were added.
Some issues were clarified. The paper matches the published version | JCAP 1505 (2015) 05, 046 | 10.1088/1475-7516/2015/05/046 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study higher derivative terms associated with scalar field cosmology. We
consider a coupling between the scalar field and the geometry inspired by the
Pais-Uhlenbeck oscillator, given by
$\alpha\partial_{\mu}\partial^{\mu}\phi\partial_{\nu}\partial^{\nu}\phi.$ We
investigate the cosmological dynamics in a phase space. For $\alpha>0$, we
provide conditions for the stability of de Sitter solutions. In this case the
crossing of the phantom divide $w_{DE}=-1$ occurs once; thereafter, the
equation of state parameter remains under this line, asymptotically reaching
towards the de Sitter solution from below. For $\alpha<0,$ which is the portion
of the parameter space where in addition to crossing the phantom divide, cyclic
behavior is possible, we present regions in the parameter space where,
according to Smilga's classification the ghost has benign or malicious
behavior.
| [
{
"created": "Mon, 25 Aug 2014 19:50:32 GMT",
"version": "v1"
},
{
"created": "Mon, 5 Jan 2015 16:17:34 GMT",
"version": "v2"
},
{
"created": "Sun, 31 May 2015 03:23:34 GMT",
"version": "v3"
}
] | 2015-06-02 | [
[
"Pulgar",
"Gustavo",
"",
"Valparaiso U., Catolica"
],
[
"Saavedra",
"Joel",
"",
"Valparaiso\n U., Catolica"
],
[
"Leon",
"Genly",
"",
"Valparaiso U., Catolica"
],
[
"Leyva",
"Yoelsy",
"",
"Tarapaca U."
]
] | We study higher derivative terms associated with scalar field cosmology. We consider a coupling between the scalar field and the geometry inspired by the Pais-Uhlenbeck oscillator, given by $\alpha\partial_{\mu}\partial^{\mu}\phi\partial_{\nu}\partial^{\nu}\phi.$ We investigate the cosmological dynamics in a phase space. For $\alpha>0$, we provide conditions for the stability of de Sitter solutions. In this case the crossing of the phantom divide $w_{DE}=-1$ occurs once; thereafter, the equation of state parameter remains under this line, asymptotically reaching towards the de Sitter solution from below. For $\alpha<0,$ which is the portion of the parameter space where in addition to crossing the phantom divide, cyclic behavior is possible, we present regions in the parameter space where, according to Smilga's classification the ghost has benign or malicious behavior. |
1603.01451 | David Kofro\v{n} | David Kofro\v{n} | Separability of test fields equations on the C-metric background | null | Phys. Rev. D 92, 124064 (2015) | 10.1103/PhysRevD.92.124064 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the Kerr-Newman spacetime the Teukolsky master equation, governing the
fundamental test fields, is of great importance. We derive an analogous master
equation for the non-rotating C-metric which encompass massless Klein-Gordon
field, neutrino field, Maxwell field, Rarita-Schwinger field and gravitational
perturbations. This equation is shown to be separable in terms of "accelerated
spin weighted spherical harmonics". It is shown that, contrary to ordinary spin
weighted spherical harmonics, the "accelerated" ones are different for
different spins. In some cases, the equation for eigenfunctions and eigenvalues
are explicitly solved.
| [
{
"created": "Fri, 4 Mar 2016 13:28:08 GMT",
"version": "v1"
}
] | 2016-03-07 | [
[
"Kofroň",
"David",
""
]
] | In the Kerr-Newman spacetime the Teukolsky master equation, governing the fundamental test fields, is of great importance. We derive an analogous master equation for the non-rotating C-metric which encompass massless Klein-Gordon field, neutrino field, Maxwell field, Rarita-Schwinger field and gravitational perturbations. This equation is shown to be separable in terms of "accelerated spin weighted spherical harmonics". It is shown that, contrary to ordinary spin weighted spherical harmonics, the "accelerated" ones are different for different spins. In some cases, the equation for eigenfunctions and eigenvalues are explicitly solved. |
gr-qc/0507028 | Thomas Buchert | Thomas Buchert | A cosmic equation of state for the inhomogeneous Universe: can a global
far-from-equilibrium state explain Dark Energy? | 7 pages, matches published version in Class. Quant. Grav | Class.Quant.Grav. 22 (2005) L113-L119 | 10.1088/0264-9381/22/19/L01 | null | gr-qc astro-ph hep-th | null | A system of effective Einstein equations for spatially averaged scalar
variables of inhomogeneous cosmological models can be solved by providing a
`cosmic equation of state'. Recent efforts to explain Dark Energy focus on
`backreaction effects' of inhomogeneities on the effective evolution of
cosmological parameters in our Hubble volume, avoiding a cosmological constant
in the equation of state. In this Letter it is argued that, if kinematical
backreaction effects are indeed of the order of the averaged density (or larger
as needed for an accelerating domain of the Universe), then the state of our
regional Hubble volume would have to be in the vicinity of a
far-from-equilibrium state that balances kinematical backreaction and average
density. This property, if interpreted globally, is shared by a stationary
cosmos with effective equation of state $p_{\rm eff} = -1/3 \rho_{\rm eff}$. It
is concluded that a confirmed explanation of Dark Energy by kinematical
backreaction may imply a paradigmatic change of cosmology.
| [
{
"created": "Thu, 7 Jul 2005 13:48:59 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Sep 2005 12:25:20 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Buchert",
"Thomas",
""
]
] | A system of effective Einstein equations for spatially averaged scalar variables of inhomogeneous cosmological models can be solved by providing a `cosmic equation of state'. Recent efforts to explain Dark Energy focus on `backreaction effects' of inhomogeneities on the effective evolution of cosmological parameters in our Hubble volume, avoiding a cosmological constant in the equation of state. In this Letter it is argued that, if kinematical backreaction effects are indeed of the order of the averaged density (or larger as needed for an accelerating domain of the Universe), then the state of our regional Hubble volume would have to be in the vicinity of a far-from-equilibrium state that balances kinematical backreaction and average density. This property, if interpreted globally, is shared by a stationary cosmos with effective equation of state $p_{\rm eff} = -1/3 \rho_{\rm eff}$. It is concluded that a confirmed explanation of Dark Energy by kinematical backreaction may imply a paradigmatic change of cosmology. |
gr-qc/9906033 | Yuri P. Goncharov | Yu. P. Goncharov (Sankt-Petersburg State Technical University, Russia) | Twisted spinors on Schwarzschild and Reissner-Nordstrom black holes | 10 pages, LaTeX with using elsart.sty | Phys.Lett. B458 (1999) 29-35 | 10.1016/S0370-2693(99)00572-9 | null | gr-qc | null | We describe twisted configurations of spinor field on the Schwarzschild and
Reissner-Nordstr\"om black holes that arise due to existence of the twisted
spinor bundles over the standard black hole topology. From a physical point of
view the appearance of spinor twisted configurations is linked with the natural
presence of Dirac monopoles that play the role of connections in the complex
line bundles corresponding to the twisted spinor bundles. Possible application
to the Hawking radiation is also outlined.
| [
{
"created": "Wed, 9 Jun 1999 19:46:17 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Goncharov",
"Yu. P.",
"",
"Sankt-Petersburg State Technical University, Russia"
]
] | We describe twisted configurations of spinor field on the Schwarzschild and Reissner-Nordstr\"om black holes that arise due to existence of the twisted spinor bundles over the standard black hole topology. From a physical point of view the appearance of spinor twisted configurations is linked with the natural presence of Dirac monopoles that play the role of connections in the complex line bundles corresponding to the twisted spinor bundles. Possible application to the Hawking radiation is also outlined. |
2402.12270 | Giulio Audagnotto | Giulio Audagnotto and Antonino Di Piazza | Dynamics, quantum states and Compton scattering in nonlinear
gravitational waves | null | J. High Energy Phys. 2024, 23 (2024) | 10.1007/JHEP06(2024)023 | null | gr-qc hep-ph hep-th | http://creativecommons.org/licenses/by/4.0/ | The classical dynamics and the construction of quantum states in a plane wave
curved spacetime are examined, paying particular attention to the similarities
with the case of an electromagnetic plane wave in flat spacetime. A natural map
connecting the dynamics of a particle in the Rosen metric and the motion of a
charged particle in an electromagnetic plane wave is unveiled. We then discuss
how this map can be translated into the quantum description by exploiting the
large number of underlying symmetries. We examine the complete analogy between
Volkov solutions and fermion states in the Rosen chart and properly extend this
to massive vector bosons. We finally report the squared S-matrix element of
Compton scattering in a sandwich plane wave spacetime in the form of a
two-dimensional integral.
| [
{
"created": "Mon, 19 Feb 2024 16:34:05 GMT",
"version": "v1"
},
{
"created": "Wed, 26 Jun 2024 09:57:21 GMT",
"version": "v2"
}
] | 2024-06-28 | [
[
"Audagnotto",
"Giulio",
""
],
[
"Di Piazza",
"Antonino",
""
]
] | The classical dynamics and the construction of quantum states in a plane wave curved spacetime are examined, paying particular attention to the similarities with the case of an electromagnetic plane wave in flat spacetime. A natural map connecting the dynamics of a particle in the Rosen metric and the motion of a charged particle in an electromagnetic plane wave is unveiled. We then discuss how this map can be translated into the quantum description by exploiting the large number of underlying symmetries. We examine the complete analogy between Volkov solutions and fermion states in the Rosen chart and properly extend this to massive vector bosons. We finally report the squared S-matrix element of Compton scattering in a sandwich plane wave spacetime in the form of a two-dimensional integral. |
gr-qc/0004082 | Jos\'e C. N. de Araujo | J.C.N. de Araujo (DAS/Inpe), A. Wang (DFT/Uerj) | Rigidly rotating dust in general relativity | 12 pages, no figures, Latex. General Relativity and Gravitation (in
press) | Gen.Rel.Grav.32:1971-1980,2000 | 10.1023/A:1001929732549 | null | gr-qc astro-ph | null | A solution to the Einstein field equations that represents a rigidly rotating
dust accompanied by a thin matter shell of the same type is found.
| [
{
"created": "Fri, 28 Apr 2000 16:53:16 GMT",
"version": "v1"
}
] | 2009-07-07 | [
[
"de Araujo",
"J. C. N.",
"",
"DAS/Inpe"
],
[
"Wang",
"A.",
"",
"DFT/Uerj"
]
] | A solution to the Einstein field equations that represents a rigidly rotating dust accompanied by a thin matter shell of the same type is found. |
gr-qc/9701034 | Paul Ohara | Paul O'Hara (Northeastern Illinois University, Chicago) | Wave-particle duality in general relativity | 11 pages, AMSTEX | Nuovo Cim. B111 (1996) 779-810 | 10.1007/BF02749012 | null | gr-qc quant-ph | null | In this paper a one to one correspondence is established between space-time
metrics of general relativity and the wave equations of quantum mechanics. This
is done by first taking the square root of the metric associated with a space
and from there, passing directly to a corresponding expression in the dual
space. It is shown that in the case of a massless particle, Maxwell's equation
for a photon follows while in the case of a particle with mass, Dirac's
equation results as a first approximation. Moreover, this one to one
correspondence suggests a natural explanation of wave-particle duality. As a
consequence, the distinction between quantum mechanics and classical
relativistic mechanics is more clearly understood and the key role of initial
conditions is emphasized. PACS NUMBERS: 03.65, 04.60
| [
{
"created": "Wed, 15 Jan 1997 16:40:07 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"O'Hara",
"Paul",
"",
"Northeastern Illinois University, Chicago"
]
] | In this paper a one to one correspondence is established between space-time metrics of general relativity and the wave equations of quantum mechanics. This is done by first taking the square root of the metric associated with a space and from there, passing directly to a corresponding expression in the dual space. It is shown that in the case of a massless particle, Maxwell's equation for a photon follows while in the case of a particle with mass, Dirac's equation results as a first approximation. Moreover, this one to one correspondence suggests a natural explanation of wave-particle duality. As a consequence, the distinction between quantum mechanics and classical relativistic mechanics is more clearly understood and the key role of initial conditions is emphasized. PACS NUMBERS: 03.65, 04.60 |
1806.10734 | Sylvain Marsat | Sylvain Marsat, John G. Baker | Fourier-domain modulations and delays of gravitational-wave signals | 41 pages, 21 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a Fourier-domain approach to modulations and delays of
gravitational wave signals, a problem which arises in two different contexts.
For space-based detectors like LISA, the orbital motion of the detector
introduces a time-dependency in the response of the detector, consisting of
both a modulation and a varying delay. In the context of signals from
precessing spinning binary systems, a useful tool for building models of the
waveform consists in representing the signal as a time-dependent rotation of a
quasi-non-precessing waveform. In both cases, being able to compute transfer
functions for these effects directly in the Fourier domain may enable
performance gains for data analysis applications by using fast frequency-domain
waveforms. Our results generalize previous approaches based on the stationary
phase approximation for inspiral signals, extending them by including delays
and computing corrections beyond the leading order, while being applicable to
the broader class of inspiral-merger-ringdown signals. In the LISA case, we
find that a leading-order treatment is accurate for high-mass and low-mass
signals that are chirping fast enough, with errors consistently reduced by the
corrections we derived. By contrast, low-mass binary black holes, if far away
from merger and slowly-chirping, cannot be handled by this formalism and we
develop another approach for these systems. In the case of precessing binaries,
we explore the merger-ringdown range for a handful of cases, using a simple
model for the post-merger precession. We find that deviations from leading
order can give large fractional errors, while affecting mainly subdominant
modes and giving rise to a limited unfaithfulness in the full waveform.
Including higher-order corrections consistently reduces the unfaithfulness, and
we further develop an alternative approach to accurately represent post-merger
features.
| [
{
"created": "Thu, 28 Jun 2018 01:52:50 GMT",
"version": "v1"
}
] | 2018-06-29 | [
[
"Marsat",
"Sylvain",
""
],
[
"Baker",
"John G.",
""
]
] | We present a Fourier-domain approach to modulations and delays of gravitational wave signals, a problem which arises in two different contexts. For space-based detectors like LISA, the orbital motion of the detector introduces a time-dependency in the response of the detector, consisting of both a modulation and a varying delay. In the context of signals from precessing spinning binary systems, a useful tool for building models of the waveform consists in representing the signal as a time-dependent rotation of a quasi-non-precessing waveform. In both cases, being able to compute transfer functions for these effects directly in the Fourier domain may enable performance gains for data analysis applications by using fast frequency-domain waveforms. Our results generalize previous approaches based on the stationary phase approximation for inspiral signals, extending them by including delays and computing corrections beyond the leading order, while being applicable to the broader class of inspiral-merger-ringdown signals. In the LISA case, we find that a leading-order treatment is accurate for high-mass and low-mass signals that are chirping fast enough, with errors consistently reduced by the corrections we derived. By contrast, low-mass binary black holes, if far away from merger and slowly-chirping, cannot be handled by this formalism and we develop another approach for these systems. In the case of precessing binaries, we explore the merger-ringdown range for a handful of cases, using a simple model for the post-merger precession. We find that deviations from leading order can give large fractional errors, while affecting mainly subdominant modes and giving rise to a limited unfaithfulness in the full waveform. Including higher-order corrections consistently reduces the unfaithfulness, and we further develop an alternative approach to accurately represent post-merger features. |
gr-qc/9307031 | Jack Gegenberg | Y. Bi and J. Gegenberg | Loop Variables in Topological Gravity | 20 pages, Latex | Class.Quant.Grav.11:883-896,1994 | 10.1088/0264-9381/11/4/008 | null | gr-qc | null | We examine the relationship between covariant and canonical
(Ashtekar/Rovelli/Smolin) loop variables in the context of BF type topological
field theories in 2+1 and 3+1 dimensions, with respective gauge groups SO(2,1)
and SO(3,1). The latter model can be considered as the simplest topological
gravity theory in 3+1 dimensions. We carry out the canonical quantization of
this model in both the connection and loop representations, for the two spatial
topologies $T^3$ and $S^2\times S^1$.
| [
{
"created": "Thu, 22 Jul 1993 17:24:00 GMT",
"version": "v1"
}
] | 2010-04-06 | [
[
"Bi",
"Y.",
""
],
[
"Gegenberg",
"J.",
""
]
] | We examine the relationship between covariant and canonical (Ashtekar/Rovelli/Smolin) loop variables in the context of BF type topological field theories in 2+1 and 3+1 dimensions, with respective gauge groups SO(2,1) and SO(3,1). The latter model can be considered as the simplest topological gravity theory in 3+1 dimensions. We carry out the canonical quantization of this model in both the connection and loop representations, for the two spatial topologies $T^3$ and $S^2\times S^1$. |
0809.5280 | Mauricio Bellini | Mariano Anabitarte, Mauricio Bellini (Mar del Plata University &
CONICET) | A confirmation of agreement of different approaches for scalar
gauge-invariant metric perturbations during inflation | Version accepted in EPJC with new title. 11 pages, no figures | null | 10.1140/epjc/s10052-009-0873-x | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We revisit an extension of the well-known formalism for gauge-invariant
scalar metric fluctuations, to study the spectrums for both, the inflaton and
gauge invariant (scalar) metric fluctuations in the framework of a single field
inflationary model where the quasi-exponential expansion is driven by an
inflation which is minimally coupled to gravity. The proposal here examined is
valid also for fluctuations with large amplitude, but for cosmological scales,
where vector and tensor perturbations can be neglected and the fluid is
irrotacional.
| [
{
"created": "Tue, 30 Sep 2008 19:37:01 GMT",
"version": "v1"
},
{
"created": "Tue, 18 Nov 2008 15:04:28 GMT",
"version": "v2"
},
{
"created": "Tue, 6 Jan 2009 17:46:59 GMT",
"version": "v3"
}
] | 2009-11-13 | [
[
"Anabitarte",
"Mariano",
"",
"Mar del Plata University &\n CONICET"
],
[
"Bellini",
"Mauricio",
"",
"Mar del Plata University &\n CONICET"
]
] | We revisit an extension of the well-known formalism for gauge-invariant scalar metric fluctuations, to study the spectrums for both, the inflaton and gauge invariant (scalar) metric fluctuations in the framework of a single field inflationary model where the quasi-exponential expansion is driven by an inflation which is minimally coupled to gravity. The proposal here examined is valid also for fluctuations with large amplitude, but for cosmological scales, where vector and tensor perturbations can be neglected and the fluid is irrotacional. |
1410.2602 | Harold Erbin | Harold Erbin | Janis-Newman algorithm: simplifications and gauge field transformation | 6 pp. (+ 1 app.). v2: minor modifications to match published version,
available at Springer via http://dx.doi.org/10.1007/s10714-015-1860-1 | Gen.Rel.Grav. 47:19 (2015) | 10.1007/s10714-015-1860-1 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Janis-Newman algorithm is an old but very powerful tool to generate
rotating solutions from static ones through a set of complex coordinate
transformations. Several solutions have been derived in this way, including
solutions with gauge fields. However, the transformation of the latter was so
far always postulated as an ad hoc result. In this paper we propose a
generalization of the procedure, extending it to the transformation of the
gauge field. We also present a simplification of the algorithm due to G.
Giampieri. We illustrate our prescription on the Kerr-Newman solution.
| [
{
"created": "Thu, 9 Oct 2014 20:00:04 GMT",
"version": "v1"
},
{
"created": "Mon, 16 Feb 2015 14:46:54 GMT",
"version": "v2"
}
] | 2015-02-17 | [
[
"Erbin",
"Harold",
""
]
] | The Janis-Newman algorithm is an old but very powerful tool to generate rotating solutions from static ones through a set of complex coordinate transformations. Several solutions have been derived in this way, including solutions with gauge fields. However, the transformation of the latter was so far always postulated as an ad hoc result. In this paper we propose a generalization of the procedure, extending it to the transformation of the gauge field. We also present a simplification of the algorithm due to G. Giampieri. We illustrate our prescription on the Kerr-Newman solution. |
2008.04780 | Sarbari Guha Dr. | Sarbari Guha and Sucheta Datta | Axial Gravitational Waves in Bianchi I Universe | 14 pages, final form accepted for publication in IJMPD | International Journal of Modern Physics D, Vol. 29, No. 16 (2020)
2050116 (21 pages) | 10.1142/S0218271820501163 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we have studied the propagation of axial gravitational waves
in Bianchi I universe using the Regge-Wheeler gauge. In this gauge, there are
only two non-zero components of $ h_{\mu\nu} $ in the case of axial waves:
$h_0(t,r)$ and $h_1(t,r)$. The field equations in absence of matter have been
derived both for the unperturbed as well as axially perturbed metric. These
field equations are solved simultaneously by assuming the expansion scalar
$\Theta$ to be proportional to the shear scalar $\sigma$ (so that $a= b^n$,
where $a$, $b$ are the metric coefficients and $n$ is an arbitrary constant),
and the wave equation for the perturbation parameter $h_0(t,r)$ have been
derived. We used the method of separation of variables to solve for this
parameter, and have subsequently determined $h_1(t,r)$. We then discuss a few
special cases in order to interpret the results. We find that the anisotropy of
the background spacetime is responsible for the damping of the gravitational
waves as they propagate through this spacetime. The perturbations depend on the
values of the angular momentum $l$. The field equations in the presence of
matter reveal that the axially perturbed spacetime leads to perturbations only
in the azimuthal velocity of the fluid leaving the matter field undisturbed.
| [
{
"created": "Sat, 8 Aug 2020 15:56:57 GMT",
"version": "v1"
},
{
"created": "Thu, 1 Oct 2020 07:02:52 GMT",
"version": "v2"
}
] | 2021-07-01 | [
[
"Guha",
"Sarbari",
""
],
[
"Datta",
"Sucheta",
""
]
] | In this paper, we have studied the propagation of axial gravitational waves in Bianchi I universe using the Regge-Wheeler gauge. In this gauge, there are only two non-zero components of $ h_{\mu\nu} $ in the case of axial waves: $h_0(t,r)$ and $h_1(t,r)$. The field equations in absence of matter have been derived both for the unperturbed as well as axially perturbed metric. These field equations are solved simultaneously by assuming the expansion scalar $\Theta$ to be proportional to the shear scalar $\sigma$ (so that $a= b^n$, where $a$, $b$ are the metric coefficients and $n$ is an arbitrary constant), and the wave equation for the perturbation parameter $h_0(t,r)$ have been derived. We used the method of separation of variables to solve for this parameter, and have subsequently determined $h_1(t,r)$. We then discuss a few special cases in order to interpret the results. We find that the anisotropy of the background spacetime is responsible for the damping of the gravitational waves as they propagate through this spacetime. The perturbations depend on the values of the angular momentum $l$. The field equations in the presence of matter reveal that the axially perturbed spacetime leads to perturbations only in the azimuthal velocity of the fluid leaving the matter field undisturbed. |
0901.4530 | Matthew Klimek | Matthew D. Klimek | Parameterized Post-Newtonian coefficients for Brans-Dicke gravity with
d+1 dimensions | 9 pages, accepted in Classical and Quantum Gravity | Class.Quant.Grav.26:065005,2009 | 10.1088/0264-9381/26/6/065005 | null | gr-qc hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present calculations of Post-Newtonian parameters for Brans-Dicke
tensor-scalar gravity in an arbitrary number of compact extra dimensions in
both the Jordan and Einstein conformal frames. We find that the parameter
gamma, which measures the amount of spacetime curvature per unit mass, becomes
a function of omega, the coefficient of the scalar kinetic term in the
Brans-Dicke Lagrangian. Experiment has placed strong constraints on gamma which
require that omega become negative in the Jordan frame for any number of extra
dimensions, highlighting that this formulation is not physical. We also confirm
the well-known result that a compact extra dimension can be equivalently viewed
as a massless scalar `dilaton.' In the Einstein frame, we find that the
behavior of gamma as constrained by experiment replicates that which is
predicted by string theory.
| [
{
"created": "Wed, 28 Jan 2009 19:05:42 GMT",
"version": "v1"
}
] | 2009-04-08 | [
[
"Klimek",
"Matthew D.",
""
]
] | We present calculations of Post-Newtonian parameters for Brans-Dicke tensor-scalar gravity in an arbitrary number of compact extra dimensions in both the Jordan and Einstein conformal frames. We find that the parameter gamma, which measures the amount of spacetime curvature per unit mass, becomes a function of omega, the coefficient of the scalar kinetic term in the Brans-Dicke Lagrangian. Experiment has placed strong constraints on gamma which require that omega become negative in the Jordan frame for any number of extra dimensions, highlighting that this formulation is not physical. We also confirm the well-known result that a compact extra dimension can be equivalently viewed as a massless scalar `dilaton.' In the Einstein frame, we find that the behavior of gamma as constrained by experiment replicates that which is predicted by string theory. |
1403.3262 | Xavier Busch | Xavier Busch, Renaud Parentani | Quantum entanglement in analogue Hawking radiation, when is the final
state non-separable ? | 14 pages, 17 figures | Phys. Rev. D 89, 105024 (2014) | 10.1103/PhysRevD.89.105024 | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the quantum entanglement of the quasiparticle pairs emitted by
analogue black holes. We use a phenomenological description of the spectra in
dispersive media to study the domains in parameter space where the final state
is non-separable. In stationary flows, three modes are involved in each sector
of fixed frequency, and not two as in homogeneous situations. The third
spectator mode acts as an environment for the pairs, and the strength of the
coupling significantly reduces the quantum coherence. The non-separability of
the pairs emitted by white holes are also considered, and compared with that of
black holes.
| [
{
"created": "Thu, 13 Mar 2014 13:41:37 GMT",
"version": "v1"
}
] | 2014-05-28 | [
[
"Busch",
"Xavier",
""
],
[
"Parentani",
"Renaud",
""
]
] | We study the quantum entanglement of the quasiparticle pairs emitted by analogue black holes. We use a phenomenological description of the spectra in dispersive media to study the domains in parameter space where the final state is non-separable. In stationary flows, three modes are involved in each sector of fixed frequency, and not two as in homogeneous situations. The third spectator mode acts as an environment for the pairs, and the strength of the coupling significantly reduces the quantum coherence. The non-separability of the pairs emitted by white holes are also considered, and compared with that of black holes. |
1601.03394 | Barry Wardell | Chris Kavanagh, Adrian C. Ottewill, Barry Wardell | Analytical high-order post-Newtonian expansions for spinning extreme
mass ratio binaries | Minor typos corrected, references added | Phys. Rev. D 93, 124038 (2016) | 10.1103/PhysRevD.93.124038 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present an analytic computation of Detweiler's redshift invariant for a
point mass in a circular orbit around a Kerr black hole, giving results up to
8.5 post-Newtonian order while making no assumptions on the magnitude of the
spin of the black hole. Our calculation is based on the functional series
method of Mano, Suzuki and Takasugi, and employs a rigorous mode-sum
regularization prescription based on the Detweiler-Whiting singular-regular
decomposition. The approximations used in our approach are minimal; we use the
standard self-force expansion to linear order in the mass ratio, and the
standard post-Newtonian expansion in the separation of the binary. A key
advantage of this approach is that it produces expressions that include
contributions at all orders in the spin of the Kerr black hole. While this work
applies the method to the specific case of Detweiler's redshift invariant, it
can be readily extended to other gauge invariant quantities and to higher
post-Newtonian orders.
| [
{
"created": "Wed, 13 Jan 2016 21:00:00 GMT",
"version": "v1"
},
{
"created": "Thu, 28 Jan 2016 13:50:23 GMT",
"version": "v2"
},
{
"created": "Thu, 16 Jun 2016 19:33:02 GMT",
"version": "v3"
},
{
"created": "Wed, 5 May 2021 10:42:34 GMT",
"version": "v4"
}
] | 2021-05-06 | [
[
"Kavanagh",
"Chris",
""
],
[
"Ottewill",
"Adrian C.",
""
],
[
"Wardell",
"Barry",
""
]
] | We present an analytic computation of Detweiler's redshift invariant for a point mass in a circular orbit around a Kerr black hole, giving results up to 8.5 post-Newtonian order while making no assumptions on the magnitude of the spin of the black hole. Our calculation is based on the functional series method of Mano, Suzuki and Takasugi, and employs a rigorous mode-sum regularization prescription based on the Detweiler-Whiting singular-regular decomposition. The approximations used in our approach are minimal; we use the standard self-force expansion to linear order in the mass ratio, and the standard post-Newtonian expansion in the separation of the binary. A key advantage of this approach is that it produces expressions that include contributions at all orders in the spin of the Kerr black hole. While this work applies the method to the specific case of Detweiler's redshift invariant, it can be readily extended to other gauge invariant quantities and to higher post-Newtonian orders. |
1812.01381 | Sergey Manida | T.Angsachon, M.E.Chaikovskii and S.N.Manida | Conservation laws for classical particles in Anti-de Sitter-Beltrami
space | 8 pages | Theor.Math.Phys., 176(1): 845-852 (2013) | null | null | gr-qc physics.class-ph physics.ed-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we consider the conservation laws for classical particles in
$AdS_4$.
At first we parameterize a geodesic line and construct conserved quantities
with analog of five dimensional Minkowski space-time $M^{(2,3)}$.
Consequently we change $AdS_4$ space to AdS-Beltrami space-time and write
conserved quantities in the Beltrami coordinates.
Finally we take a limit for small velocity $\dot{x}\ll c$ and we get the
conserved quantities in Lorentz-Fock space-time. And finally we give out the
energy of the nonrelativistic noncosmological particle under the cosmological
limit.
| [
{
"created": "Tue, 4 Dec 2018 12:43:56 GMT",
"version": "v1"
}
] | 2018-12-05 | [
[
"Angsachon",
"T.",
""
],
[
"Chaikovskii",
"M. E.",
""
],
[
"Manida",
"S. N.",
""
]
] | In this paper we consider the conservation laws for classical particles in $AdS_4$. At first we parameterize a geodesic line and construct conserved quantities with analog of five dimensional Minkowski space-time $M^{(2,3)}$. Consequently we change $AdS_4$ space to AdS-Beltrami space-time and write conserved quantities in the Beltrami coordinates. Finally we take a limit for small velocity $\dot{x}\ll c$ and we get the conserved quantities in Lorentz-Fock space-time. And finally we give out the energy of the nonrelativistic noncosmological particle under the cosmological limit. |
0909.3329 | Steven Carlip | Steven Carlip | Spontaneous Dimensional Reduction in Short-Distance Quantum Gravity? | 9 pages, aip macros. Invited talk at the XXV Max Born Symposium,
"Physics at the Planck scale," Wroclaw (Poland), June 29--July 3, 2009; to
appear in the Proceedings | null | 10.1063/1.3284402 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Several lines of evidence suggest that quantum gravity at very short
distances may behave effectively as a two-dimensional theory. I summarize these
hints, and offer an additional argument based on the strong-coupling limit of
the Wheeler-DeWitt equation. The resulting scenario suggests a novel approach
to quantum gravity at the Planck scale.
| [
{
"created": "Thu, 17 Sep 2009 22:02:32 GMT",
"version": "v1"
}
] | 2015-05-14 | [
[
"Carlip",
"Steven",
""
]
] | Several lines of evidence suggest that quantum gravity at very short distances may behave effectively as a two-dimensional theory. I summarize these hints, and offer an additional argument based on the strong-coupling limit of the Wheeler-DeWitt equation. The resulting scenario suggests a novel approach to quantum gravity at the Planck scale. |
gr-qc/0210065 | Lorenzo Iorio | Lorenzo Iorio | Testing General Relativity with Satellite Laser Ranging: Recent
Developments | Latex2e, 10 pages, no figures, no tables. Paper presented at
COSPAR2002 conference held in Houston, TX, from 10 October 2002 to 19 October
2002. To appear in Advance in Space Research. References added and updated | Adv.SpaceRes.39:236-243,2007 | 10.1016/j.asr.2006.04.010 | null | gr-qc astro-ph physics.space-ph | null | In this paper the most recent developments in testing General Relativity in
the gravitational field of the Earth with the technique of Satellite Laser
Ranging are presented. In particular, we concentrate our attention on some
gravitoelectric and gravitomagnetic post--Newtonian orbital effects on the
motion of a test body in the external field of a central mass.
| [
{
"created": "Sat, 19 Oct 2002 06:39:21 GMT",
"version": "v1"
},
{
"created": "Sat, 19 Jul 2003 06:36:26 GMT",
"version": "v2"
},
{
"created": "Thu, 18 Sep 2003 12:42:26 GMT",
"version": "v3"
},
{
"created": "Mon, 22 Sep 2003 12:38:12 GMT",
"version": "v4"
}
] | 2009-09-29 | [
[
"Iorio",
"Lorenzo",
""
]
] | In this paper the most recent developments in testing General Relativity in the gravitational field of the Earth with the technique of Satellite Laser Ranging are presented. In particular, we concentrate our attention on some gravitoelectric and gravitomagnetic post--Newtonian orbital effects on the motion of a test body in the external field of a central mass. |
0705.2133 | Ying-Qiu Gu | Ying-Qiu Gu | The Exact Solutions to the Gravitational Contraction in Comoving
Coordinate System | 9 pages, 1 figure | null | null | null | gr-qc astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The gravitational collapse of a star is a warmly discussed but still puzzling
problem, which not only involves the dynamics of the gases, but also the subtle
coordinate transformation. In this letter, we give some more detailed
investigation on this problem, and reach the results: (I). The comoving
coordinate system for the stellar system is only compatible with the
zero-pressure free falling particles. (II). For the free falling dust, there
are three kind of solutions respectively corresponding to the oscillating, the
critical and the open trajectories. The solution of Oppenheimer and Snyder is
the critical case. (III). All solutions are exactly derived. There is a new
kind singularity in the solution, but its origin is unclear.
| [
{
"created": "Tue, 15 May 2007 12:35:47 GMT",
"version": "v1"
},
{
"created": "Sat, 25 Apr 2009 03:08:13 GMT",
"version": "v2"
}
] | 2009-04-30 | [
[
"Gu",
"Ying-Qiu",
""
]
] | The gravitational collapse of a star is a warmly discussed but still puzzling problem, which not only involves the dynamics of the gases, but also the subtle coordinate transformation. In this letter, we give some more detailed investigation on this problem, and reach the results: (I). The comoving coordinate system for the stellar system is only compatible with the zero-pressure free falling particles. (II). For the free falling dust, there are three kind of solutions respectively corresponding to the oscillating, the critical and the open trajectories. The solution of Oppenheimer and Snyder is the critical case. (III). All solutions are exactly derived. There is a new kind singularity in the solution, but its origin is unclear. |
1208.5512 | Gaetano Lambiase | G. Lambiase | Constraints on massive gravity theory from big bang nucleosynthesis | 5 pages | null | 10.1088/1475-7516/2012/10/028 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The massive gravity cosmology is studied in the scenario of big bang
nucleosynthesis. By making use of current bounds on the deviation from the
fractional mass, we derive the constraints on the free parameters of the
theory. The cosmological consequences of the model are also discussed in the
framework of the PAMELA experiment.
| [
{
"created": "Mon, 27 Aug 2012 21:28:54 GMT",
"version": "v1"
}
] | 2015-06-11 | [
[
"Lambiase",
"G.",
""
]
] | The massive gravity cosmology is studied in the scenario of big bang nucleosynthesis. By making use of current bounds on the deviation from the fractional mass, we derive the constraints on the free parameters of the theory. The cosmological consequences of the model are also discussed in the framework of the PAMELA experiment. |
1203.5890 | Han Dong | Han Dong, Ying-bin Wang and Xin-he Meng | Extended Birkhoff's Theorem in the f(T) Gravity | 7 pages, 1 figure, submitted to EPJ-C. arXiv admin note: substantial
text overlap with arXiv:1107.0629 | null | 10.1140/epjc/s10052-012-2002-5 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The f(T) theory, a generally modified teleparallel gravity, has been proposed
as an alternative gravity model to account for the dark energy phenomena.
Following our previous work [Xin-he Meng and Ying-bin Wang, EPJC(2011),
arXiv:1107.0629v1], we prove that the Birkhoff's theorem holds in a more
general context, specifically with the off diagonal tetrad case, in this
communication letter. Then, we discuss respectively the results of the external
vacuum and internal gravitational field in the f(T) gravity framework, as well
as the extended meaning of this theorem. We also investigate the validity of
the Birkhoff's theorem in the frame of f(T) gravity via conformal
transformation by regarding the Brans-Dicke-like scalar as effective matter,
and study the equivalence between both Einstein frame and Jordan frame.
| [
{
"created": "Tue, 27 Mar 2012 08:03:50 GMT",
"version": "v1"
},
{
"created": "Wed, 18 Apr 2012 13:37:21 GMT",
"version": "v2"
}
] | 2015-06-04 | [
[
"Dong",
"Han",
""
],
[
"Wang",
"Ying-bin",
""
],
[
"Meng",
"Xin-he",
""
]
] | The f(T) theory, a generally modified teleparallel gravity, has been proposed as an alternative gravity model to account for the dark energy phenomena. Following our previous work [Xin-he Meng and Ying-bin Wang, EPJC(2011), arXiv:1107.0629v1], we prove that the Birkhoff's theorem holds in a more general context, specifically with the off diagonal tetrad case, in this communication letter. Then, we discuss respectively the results of the external vacuum and internal gravitational field in the f(T) gravity framework, as well as the extended meaning of this theorem. We also investigate the validity of the Birkhoff's theorem in the frame of f(T) gravity via conformal transformation by regarding the Brans-Dicke-like scalar as effective matter, and study the equivalence between both Einstein frame and Jordan frame. |
gr-qc/0504021 | Xu Lixin | Hongya Liu, Huanying Liu, Baorong Chang, Lixin Xu | Induced Phantom and 5D Attractor Solution in Space-Time-Matter Theory | ws-mpla.cls, 9 pages, 1 figure, new references added | Mod.Phys.Lett. A20 (2005) 1973-1982 | 10.1142/S0217732305017366 | null | gr-qc astro-ph hep-th | null | In Spacetime-Matter theory we assume that the 4D induced matter of the $5D $
Ricci-flat bouncing cosmological solutions contains a perfect fluid as well as
an induced scalar field. Then we show that the conventional 4D quintessence and
phantom models of dark energy could be recovered from the $5D$ cosmological
solutions. By using the phase-plane analysis to study the stability of
evolution of the $5D$ models, we find that the conventional 4D late-time
attractor solution is also recovered. This attractor solution shows that the
scale factors of the phantom dominated universes in both the 4D and $5D$
theories will reach infinity in a finite time and the universes will be ended
at a new kind of spacetime singularity at which everything will be annihilated.
We also find that the repulsive force of the phantom may provide us with a
mechanics to explain the bounce.
| [
{
"created": "Wed, 6 Apr 2005 04:03:35 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Jul 2005 07:21:07 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Liu",
"Hongya",
""
],
[
"Liu",
"Huanying",
""
],
[
"Chang",
"Baorong",
""
],
[
"Xu",
"Lixin",
""
]
] | In Spacetime-Matter theory we assume that the 4D induced matter of the $5D $ Ricci-flat bouncing cosmological solutions contains a perfect fluid as well as an induced scalar field. Then we show that the conventional 4D quintessence and phantom models of dark energy could be recovered from the $5D$ cosmological solutions. By using the phase-plane analysis to study the stability of evolution of the $5D$ models, we find that the conventional 4D late-time attractor solution is also recovered. This attractor solution shows that the scale factors of the phantom dominated universes in both the 4D and $5D$ theories will reach infinity in a finite time and the universes will be ended at a new kind of spacetime singularity at which everything will be annihilated. We also find that the repulsive force of the phantom may provide us with a mechanics to explain the bounce. |
gr-qc/0402086 | Raul Vera | Ra\"ul Vera | On the construction of global models describing isolated rotating
charged bodies; uniqueness of the exterior gravitational field | LaTeX, 6pages, uses indentfirst package. To appear in the proceedings
of the Spanish Relativity Meeting ERE'03 | null | null | null | gr-qc | null | A relatively recent study by Mars and Senovilla provided us with a uniqueness
result for the exterior vacuum gravitational field of global models describing
finite isolated rotating bodies in equilibrium in General Relativity (GR). The
generalisation to exterior electrovacuum gravitational fields, to include
charged rotating objects, is presented here.
| [
{
"created": "Thu, 19 Feb 2004 20:15:19 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Vera",
"Raül",
""
]
] | A relatively recent study by Mars and Senovilla provided us with a uniqueness result for the exterior vacuum gravitational field of global models describing finite isolated rotating bodies in equilibrium in General Relativity (GR). The generalisation to exterior electrovacuum gravitational fields, to include charged rotating objects, is presented here. |
gr-qc/0505020 | Diego Pavon | Diego Pavon and Winfried Zimdahl | Holographic dark energy and cosmic coincidence | 9 pages, no figures, references updated, typos eliminated. To be
published in Physics Letters B | Phys.Lett.B628:206-210,2005 | 10.1016/j.physletb.2005.08.134 | null | gr-qc astro-ph hep-th | null | In this Letter we demonstrate that any interaction of pressureless dark
matter with holographic dark energy, whose infrared cutoff is set by the Hubble
scale, implies a constant ratio of the energy densities of both components thus
solving the coincidence problem. The equation of state parameter is obtained as
a function of the interaction strength. For a variable degree of saturation of
the holographic bound the energy density ratio becomes time dependent which is
compatible with a transition from decelerated to accelerated expansion.
| [
{
"created": "Wed, 4 May 2005 09:48:35 GMT",
"version": "v1"
},
{
"created": "Fri, 22 Jul 2005 11:14:42 GMT",
"version": "v2"
},
{
"created": "Mon, 26 Sep 2005 13:02:51 GMT",
"version": "v3"
}
] | 2009-09-29 | [
[
"Pavon",
"Diego",
""
],
[
"Zimdahl",
"Winfried",
""
]
] | In this Letter we demonstrate that any interaction of pressureless dark matter with holographic dark energy, whose infrared cutoff is set by the Hubble scale, implies a constant ratio of the energy densities of both components thus solving the coincidence problem. The equation of state parameter is obtained as a function of the interaction strength. For a variable degree of saturation of the holographic bound the energy density ratio becomes time dependent which is compatible with a transition from decelerated to accelerated expansion. |
1505.03317 | Joan Josep Ferrando | Joan Josep Ferrando and Juan Antonio S\'aez | Birkhoff theorem and conformal Killing-Yano tensors | 7 pages; accepted in General Relativity and Gravitation | Gen Relativ Gravit (2015) 47:66 | 10.1007/s10714-015-1911-7 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyze the main geometric conditions imposed by the hypothesis of the
Jebsen-Birkhoff theorem. We show that the result (existence of an additional
Killing vector) does not necessarily require a three-dimensional isometry group
on two-dimensional orbits but only the existence of a conformal Killing-Yano
tensor. In this approach the (additional) isometry appears as the known
invariant Killing vector that the ${\cal D}$-metrics admit.
| [
{
"created": "Wed, 13 May 2015 10:37:42 GMT",
"version": "v1"
}
] | 2015-06-23 | [
[
"Ferrando",
"Joan Josep",
""
],
[
"Sáez",
"Juan Antonio",
""
]
] | We analyze the main geometric conditions imposed by the hypothesis of the Jebsen-Birkhoff theorem. We show that the result (existence of an additional Killing vector) does not necessarily require a three-dimensional isometry group on two-dimensional orbits but only the existence of a conformal Killing-Yano tensor. In this approach the (additional) isometry appears as the known invariant Killing vector that the ${\cal D}$-metrics admit. |
1701.00819 | Carlos Hidalgo | Roberto A. Sussman, Juan Carlos Hidalgo, Ismael Delgado Gaspar and
Gabriel German | Non-Spherical Szekeres models in the language of Cosmological
Perturbations | V2: Minor comments and a couple of references added. Version accepted
for publication in PRD | Phys. Rev. D 95, 064033 (2017) | 10.1103/PhysRevD.95.064033 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the differences and equivalences between the non-perturbative
description of the evolution of cosmic structure furnished by the Szekeres dust
models (a non-spherical exact solution of Einstein's equations) and the
dynamics of Cosmological Perturbation Theory (CPT) for dust sources in a
$\Lambda$CDM background. We show how the dynamics of Szekeres models can be
described by evolution equations given in terms of "exact fluctuations" that
identically reduce (at all orders) to evolution equations of CPT in the
comoving isochronous gauge. We explicitly show how Szekeres linearised exact
fluctuations are specific (deterministic) realisations of standard linear
perturbations of CPT given as random fields but, as opposed to the latter
perturbations, they can be evolved exactly into the full non-linear regime. We
prove two important results: (i) the conservation of the curvature perturbation
(at all scales) also holds for the appropriate approximation of the exact
Szekeres fluctuations in a $\Lambda$CDM background, and (ii) the different
collapse morphologies of Szekeres models yields, at nonlinear order, different
functional forms for the growth factor that follows from the study of redshift
space distortions. The metric based potentials used in linear CPT are computed
in terms of the parameters of the linearised Szekeres models, thus allowing us
to relate our results to linear CPT results in other gauges. We believe that
these results provide a solid starting stage to examine the role of
non-perturbative General Relativity in current cosmological research.
| [
{
"created": "Mon, 2 Jan 2017 18:37:21 GMT",
"version": "v1"
},
{
"created": "Tue, 28 Mar 2017 21:48:14 GMT",
"version": "v2"
}
] | 2017-04-05 | [
[
"Sussman",
"Roberto A.",
""
],
[
"Hidalgo",
"Juan Carlos",
""
],
[
"Gaspar",
"Ismael Delgado",
""
],
[
"German",
"Gabriel",
""
]
] | We study the differences and equivalences between the non-perturbative description of the evolution of cosmic structure furnished by the Szekeres dust models (a non-spherical exact solution of Einstein's equations) and the dynamics of Cosmological Perturbation Theory (CPT) for dust sources in a $\Lambda$CDM background. We show how the dynamics of Szekeres models can be described by evolution equations given in terms of "exact fluctuations" that identically reduce (at all orders) to evolution equations of CPT in the comoving isochronous gauge. We explicitly show how Szekeres linearised exact fluctuations are specific (deterministic) realisations of standard linear perturbations of CPT given as random fields but, as opposed to the latter perturbations, they can be evolved exactly into the full non-linear regime. We prove two important results: (i) the conservation of the curvature perturbation (at all scales) also holds for the appropriate approximation of the exact Szekeres fluctuations in a $\Lambda$CDM background, and (ii) the different collapse morphologies of Szekeres models yields, at nonlinear order, different functional forms for the growth factor that follows from the study of redshift space distortions. The metric based potentials used in linear CPT are computed in terms of the parameters of the linearised Szekeres models, thus allowing us to relate our results to linear CPT results in other gauges. We believe that these results provide a solid starting stage to examine the role of non-perturbative General Relativity in current cosmological research. |
2204.04506 | Tiberiu Harko | Rattanasak Hama, Tiberiu Harko, Sorin V. Sabau | Dark energy and accelerating cosmological evolution from osculating
Barthel-Kropina geometry | 25 pages, 7 figures, accepted for publication in EPJC | null | 10.1140/epjc/s10052-022-10318-9 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Finsler geometry is an important extension of Riemann geometry, in which to
each point of the spacetime manifold an arbitrary internal variable is
associated. Interesting Finsler geometries, with many physical applications,
are the Randers and Kropina type geometries, respectively. A subclass of
Finsler geometries is represented by the osculating Finsler spaces, in which
the internal variable is a function of the base manifold coordinates only. In
an osculating Finsler geometry one introduces the Barthel connection, which has
the remarkable property that it is the Levi-Civita connection of a Riemannian
metric. In the present work we consider the gravitational and cosmological
implications of a Barthel-Kropina type geometry. We assume that in this
geometry the Ricci type curvatures are related to the matter energy-momentum
tensor by the standard Einstein equations. The generalized Friedmann equations
in the Barthel-Kropina geometry are obtained by considering that the background
Riemannian metric is of Friedmann-Lemaitre-Robertson-Walker type. The matter
energy balance equation is also derived. The cosmological properties of the
model are investigated in detail, and it is shown that the model admits a de
Sitter type solution, and that an effective dark energy component can also be
generated. Several cosmological solutions are also obtained by numerically
integrating the generalized Friedmann equations. A comparison of two specific
classes of models with the observational data and with the standard
$\Lambda$CDM model is also performed, and it turns out that the Barthel-Kropina
type models give a satisfactory description of the observations.
| [
{
"created": "Sat, 9 Apr 2022 16:14:04 GMT",
"version": "v1"
}
] | 2022-05-18 | [
[
"Hama",
"Rattanasak",
""
],
[
"Harko",
"Tiberiu",
""
],
[
"Sabau",
"Sorin V.",
""
]
] | Finsler geometry is an important extension of Riemann geometry, in which to each point of the spacetime manifold an arbitrary internal variable is associated. Interesting Finsler geometries, with many physical applications, are the Randers and Kropina type geometries, respectively. A subclass of Finsler geometries is represented by the osculating Finsler spaces, in which the internal variable is a function of the base manifold coordinates only. In an osculating Finsler geometry one introduces the Barthel connection, which has the remarkable property that it is the Levi-Civita connection of a Riemannian metric. In the present work we consider the gravitational and cosmological implications of a Barthel-Kropina type geometry. We assume that in this geometry the Ricci type curvatures are related to the matter energy-momentum tensor by the standard Einstein equations. The generalized Friedmann equations in the Barthel-Kropina geometry are obtained by considering that the background Riemannian metric is of Friedmann-Lemaitre-Robertson-Walker type. The matter energy balance equation is also derived. The cosmological properties of the model are investigated in detail, and it is shown that the model admits a de Sitter type solution, and that an effective dark energy component can also be generated. Several cosmological solutions are also obtained by numerically integrating the generalized Friedmann equations. A comparison of two specific classes of models with the observational data and with the standard $\Lambda$CDM model is also performed, and it turns out that the Barthel-Kropina type models give a satisfactory description of the observations. |
gr-qc/9308014 | null | Riccardo Capovilla | No New Symmetries of the Vacuum Einstein Equations | 9 pages, TeX | Phys.Rev. D49 (1994) 879-882 | 10.1103/PhysRevD.49.879 | null | gr-qc | null | In this note we examine some recently proposed solutions of the linearized
vacuum Einstein equations. We show that such solutions are {\it not} symmetries
of the Einstein equations, because of a crucial integrability condition.
| [
{
"created": "Mon, 16 Aug 1993 21:23:00 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Capovilla",
"Riccardo",
""
]
] | In this note we examine some recently proposed solutions of the linearized vacuum Einstein equations. We show that such solutions are {\it not} symmetries of the Einstein equations, because of a crucial integrability condition. |
1010.4104 | Yohsuke Takamori | Yohsuke Takamori, Ken-ichi Nakao, Hideki Ishihara, Masashi Kimura,
Chul-Moon Yoo | Perturbative Analysis of a Stationary Magnetosphere in an Extreme Black
Hole Spacetime : On the Meissner-like Effect of an Extreme Black Hole | 30 pages, 3 figures | null | 10.1111/j.1365-2966.2010.18063.x | OCU-PHYS-339, YITP-10-79, AP-GR-83 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is known that the Meissner-like effect is seen in a magnetosphere without
an electric current in black hole spacetime: no non-monopole component of
magnetic flux penetrates the event horizon if the black hole is extreme. In
this paper, in order to see how an electric current affects the Meissner-like
effect, we study a force-free electromagnetic system in a static and
spherically symmetric extreme black hole spacetime. By assuming that the
rotational angular velocity of the magnetic field is very small, we construct a
perturbative solution for the Grad-Shafranov equation, which is the basic
equation to determine a stationary, axisymmetric electromagnetic field with a
force-free electric current. Our perturbation analysis reveals that, if an
electric current exists, higher multipole components may be superposed upon the
monopole component on the event horizon, even if the black hole is extreme.
| [
{
"created": "Wed, 20 Oct 2010 05:34:10 GMT",
"version": "v1"
}
] | 2015-05-20 | [
[
"Takamori",
"Yohsuke",
""
],
[
"Nakao",
"Ken-ichi",
""
],
[
"Ishihara",
"Hideki",
""
],
[
"Kimura",
"Masashi",
""
],
[
"Yoo",
"Chul-Moon",
""
]
] | It is known that the Meissner-like effect is seen in a magnetosphere without an electric current in black hole spacetime: no non-monopole component of magnetic flux penetrates the event horizon if the black hole is extreme. In this paper, in order to see how an electric current affects the Meissner-like effect, we study a force-free electromagnetic system in a static and spherically symmetric extreme black hole spacetime. By assuming that the rotational angular velocity of the magnetic field is very small, we construct a perturbative solution for the Grad-Shafranov equation, which is the basic equation to determine a stationary, axisymmetric electromagnetic field with a force-free electric current. Our perturbation analysis reveals that, if an electric current exists, higher multipole components may be superposed upon the monopole component on the event horizon, even if the black hole is extreme. |
1806.06754 | Arman Tursunov | Arman Tursunov, Martin Kolo\v{s} and Zden\v{e}k Stuchl\'ik | Orbital widening due to radiation reaction around a magnetized black
hole | 6 pages, 2 figures | Astron. Nachrichten 339, 341 (2018) | 10.1002/asna.201813502 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Radiation reaction acting on a charged particle moving at a stable circular
orbit of a magnetized black hole can lead to the shift of the orbital radius
outwards from the black hole. The effect causes increase of the energy and
angular momentum of the particle measured by an observer at rest at infinity.
In this note we show that "widening" of such orbits is independent of the field
configuration, however, it appears only in the cases with the external Lorentz
force acting outwards from the black hole. This condition corresponds to $q L B
> 0$, where $q$ and $L$ are the charge and angular momentum of the particle and
$B$ is intensity of the external magnetic field. As examples of the orbital
widening we consider two scenarios with an external homogeneous magnetic field
and a magnetic dipole field generated by a current loop around a Schwarzschild
black hole. We show that the orbital widening is accompanied by quasi-harmonic
oscillations of the particle which are considerably large in the magnetic
dipole fields. We also estimate the timescales of orbital widening from which
it follows that the effect can be relevant in the vicinity of stellar mass
black holes.
| [
{
"created": "Mon, 18 Jun 2018 15:09:42 GMT",
"version": "v1"
}
] | 2018-11-06 | [
[
"Tursunov",
"Arman",
""
],
[
"Kološ",
"Martin",
""
],
[
"Stuchlík",
"Zdeněk",
""
]
] | Radiation reaction acting on a charged particle moving at a stable circular orbit of a magnetized black hole can lead to the shift of the orbital radius outwards from the black hole. The effect causes increase of the energy and angular momentum of the particle measured by an observer at rest at infinity. In this note we show that "widening" of such orbits is independent of the field configuration, however, it appears only in the cases with the external Lorentz force acting outwards from the black hole. This condition corresponds to $q L B > 0$, where $q$ and $L$ are the charge and angular momentum of the particle and $B$ is intensity of the external magnetic field. As examples of the orbital widening we consider two scenarios with an external homogeneous magnetic field and a magnetic dipole field generated by a current loop around a Schwarzschild black hole. We show that the orbital widening is accompanied by quasi-harmonic oscillations of the particle which are considerably large in the magnetic dipole fields. We also estimate the timescales of orbital widening from which it follows that the effect can be relevant in the vicinity of stellar mass black holes. |
2203.14519 | Ken-Ichi Nakao | Ken-ichi Nakao, Kazumasa Okabayashi, Tomohiro Harada | Radiative gravastar with Gibbons-Hawking temperature | Revised version with 33 pages, 3 figures | null | 10.1103/PhysRevD.106.105006 | OCU-PHYS-560, AP-GR-180, NITEP 133, RUP-22-7 | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We study the quantum particle creation in a toy model of spherically
symmetric gravitational collapse whose final product is not a black hole but a
gravastar. Precedent studies revealed that even in the case of the
gravitational collapse to form a horizonless ultra-compact object, thermal
radiation named transient Hawking radiation is generated at the late stage of
the gravitational collapse, and a sudden stop of collapsing motion to form a
horizonless ultra-compact object causes one or two bursts of quantum particle
creation. The very different behavior of the model studied in this paper from
the precedent ones is quantum radiation with a thermal spectrum from the
gravastar between two bursts. The temperature of the radiation is not the same
as the Hawking one determined by the gravitational mass of the system but the
Gibbons-Hawking one of the de Sitter core inside the gravastar.
| [
{
"created": "Mon, 28 Mar 2022 06:21:48 GMT",
"version": "v1"
},
{
"created": "Thu, 11 Aug 2022 20:27:16 GMT",
"version": "v2"
}
] | 2022-11-23 | [
[
"Nakao",
"Ken-ichi",
""
],
[
"Okabayashi",
"Kazumasa",
""
],
[
"Harada",
"Tomohiro",
""
]
] | We study the quantum particle creation in a toy model of spherically symmetric gravitational collapse whose final product is not a black hole but a gravastar. Precedent studies revealed that even in the case of the gravitational collapse to form a horizonless ultra-compact object, thermal radiation named transient Hawking radiation is generated at the late stage of the gravitational collapse, and a sudden stop of collapsing motion to form a horizonless ultra-compact object causes one or two bursts of quantum particle creation. The very different behavior of the model studied in this paper from the precedent ones is quantum radiation with a thermal spectrum from the gravastar between two bursts. The temperature of the radiation is not the same as the Hawking one determined by the gravitational mass of the system but the Gibbons-Hawking one of the de Sitter core inside the gravastar. |
1606.04343 | Philip David Flammer | Philip David Flammer | Spinning solutions in general relativity with infinite central density | 14 pages, 6 figures | Flammer, P.D. Gen Relativ Gravit (2018) 50: 51.
https://doi.org/10.1007/s10714-018-2371-7 | 10.1007/s10714-018-2371-7 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper presents general relativistic numerical simulations of uniformly
rotating polytropes. Equations are developed using MSQI coordinates, but taking
a logarithm of the radial coordinate. The result is relatively simple
elliptical differential equations. Due to the logarithmic scale, we can resolve
solutions with near-singular mass distributions near their center, while the
solution domain extends many orders of magnitude larger than the radius of the
distribution (to connect with flat space-time). Rotating solutions are found
with very high central energy densities for a range of adiabatic exponents.
Analytically, assuming the pressure is proportional to the energy density
(which is true for polytropes in the limit of large energy density), we
determine the small radius behavior of the metric potentials and energy
density. This small radius behavior agrees well with the small radius behavior
of large central density numerical results, lending confidence to our numerical
approach. We compare results with rotating solutions available in the
literature, which show good agreement. We study the stability of spherical
solutions: instability sets in at the first maximum in mass versus central
energy density; this is also consistent with results in the literature, and
further lends confidence to the numerical approach.
| [
{
"created": "Mon, 13 Jun 2016 15:19:16 GMT",
"version": "v1"
},
{
"created": "Fri, 4 Aug 2017 23:32:14 GMT",
"version": "v2"
},
{
"created": "Thu, 19 Oct 2017 17:30:39 GMT",
"version": "v3"
},
{
"created": "Tue, 24 Apr 2018 05:47:15 GMT",
"version": "v4"
}
] | 2018-04-25 | [
[
"Flammer",
"Philip David",
""
]
] | This paper presents general relativistic numerical simulations of uniformly rotating polytropes. Equations are developed using MSQI coordinates, but taking a logarithm of the radial coordinate. The result is relatively simple elliptical differential equations. Due to the logarithmic scale, we can resolve solutions with near-singular mass distributions near their center, while the solution domain extends many orders of magnitude larger than the radius of the distribution (to connect with flat space-time). Rotating solutions are found with very high central energy densities for a range of adiabatic exponents. Analytically, assuming the pressure is proportional to the energy density (which is true for polytropes in the limit of large energy density), we determine the small radius behavior of the metric potentials and energy density. This small radius behavior agrees well with the small radius behavior of large central density numerical results, lending confidence to our numerical approach. We compare results with rotating solutions available in the literature, which show good agreement. We study the stability of spherical solutions: instability sets in at the first maximum in mass versus central energy density; this is also consistent with results in the literature, and further lends confidence to the numerical approach. |
2208.04982 | Ding Jia | Ding Jia | Light ray fluctuation and lattice refinement of simplicial quantum
gravity | minor updates to improve presentation, 30 pages, 21 figures, matches
well with the published version | null | 10.1088/1361-6382/acd97e | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In several approaches of non-perturbative quantum gravity, a major
outstanding problem is to obtain results valid at the infinite lattice
refinement limit. Working with Lorentzian simplicial quantum gravity, we
compute light ray fluctuation probabilities in 3D and 4D across different
lattices. In a simplified refined box model with the Einstein-Hilbert action,
numerical results show that lattice refinement does not simply suppress or
simply enhance light ray fluctuations, but actually drives very wide and very
narrow light probability distributions towards intermediate ones. A comparison
across lattices and across couplings reveals numerical hints at a lattice
refinement fixed point associated with a universality class of couplings. The
results fit the intuition that quantum spacetime fluctuations reflected by
light ray fluctuations start wild microscopically and become mild
macroscopically. The refined box model is limited by the assumption of a rigid
frame at all scales. The present results suggest further studies around the
zero-coupling limit to relax the simplifying assumptions of the model.
| [
{
"created": "Tue, 9 Aug 2022 18:18:52 GMT",
"version": "v1"
},
{
"created": "Wed, 29 Nov 2023 20:55:12 GMT",
"version": "v2"
}
] | 2023-12-01 | [
[
"Jia",
"Ding",
""
]
] | In several approaches of non-perturbative quantum gravity, a major outstanding problem is to obtain results valid at the infinite lattice refinement limit. Working with Lorentzian simplicial quantum gravity, we compute light ray fluctuation probabilities in 3D and 4D across different lattices. In a simplified refined box model with the Einstein-Hilbert action, numerical results show that lattice refinement does not simply suppress or simply enhance light ray fluctuations, but actually drives very wide and very narrow light probability distributions towards intermediate ones. A comparison across lattices and across couplings reveals numerical hints at a lattice refinement fixed point associated with a universality class of couplings. The results fit the intuition that quantum spacetime fluctuations reflected by light ray fluctuations start wild microscopically and become mild macroscopically. The refined box model is limited by the assumption of a rigid frame at all scales. The present results suggest further studies around the zero-coupling limit to relax the simplifying assumptions of the model. |
gr-qc/9707013 | Yuri Levin | Yuri Levin | Internal thermal noise in the LIGO test masses : a direct approach | 6 pages, RevTex, 1 figure | Phys.Rev.D57:659-663,1998 | 10.1103/PhysRevD.57.659 | null | gr-qc | null | The internal thermal noise in LIGO's test masses is analyzed by a new
technique, a direct application of the Fluctuation-Dissipation Theorem to
LIGO's readout observable, $x(t)=$(longitudinal position of test-mass face,
weighted by laser beam's Gaussian profile). Previous analyses, which relied on
a normal-mode decomposition of the test-mass motion, were valid only if the
dissipation is uniformally distributed over the test-mass interior, and they
converged reliably to a final answer only when the beam size was a
non-negligible fraction of the test-mass cross section. This paper's direct
analysis, by contrast, can handle inhomogeneous dissipation and arbitrary beam
sizes. In the domain of validity of the previous analysis, the two methods give
the same answer for $S_x(f)$, the spectral density of thermal noise, to within
expected accuracy. The new analysis predicts that thermal noise due to
dissipation concentrated in the test mass's front face (e.g. due to mirror
coating) scales as $1/r_0^2$, by contrast with homogeneous dissipation, which
scales as $1/r_0$ ($r_0$ is the beam radius); so surface dissipation could
become significant for small beam sizes.
| [
{
"created": "Fri, 4 Jul 1997 20:34:01 GMT",
"version": "v1"
}
] | 2009-12-30 | [
[
"Levin",
"Yuri",
""
]
] | The internal thermal noise in LIGO's test masses is analyzed by a new technique, a direct application of the Fluctuation-Dissipation Theorem to LIGO's readout observable, $x(t)=$(longitudinal position of test-mass face, weighted by laser beam's Gaussian profile). Previous analyses, which relied on a normal-mode decomposition of the test-mass motion, were valid only if the dissipation is uniformally distributed over the test-mass interior, and they converged reliably to a final answer only when the beam size was a non-negligible fraction of the test-mass cross section. This paper's direct analysis, by contrast, can handle inhomogeneous dissipation and arbitrary beam sizes. In the domain of validity of the previous analysis, the two methods give the same answer for $S_x(f)$, the spectral density of thermal noise, to within expected accuracy. The new analysis predicts that thermal noise due to dissipation concentrated in the test mass's front face (e.g. due to mirror coating) scales as $1/r_0^2$, by contrast with homogeneous dissipation, which scales as $1/r_0$ ($r_0$ is the beam radius); so surface dissipation could become significant for small beam sizes. |
2201.07979 | Pooya Farokhi | Pooya Farokhi | Shape Dynamics and The Universe: Foundations and Implications | 118 pages, 12 figures, 1 table, Bachelor thesis | null | null | null | gr-qc | http://creativecommons.org/licenses/by-nc-nd/4.0/ | Shape dynamics is an alternative background-independent approach to classical
dynamics that implements Leibnizian philosophy and Mach's Principles. It is a
formulation of the dynamics of the universe in terms of the intrinsic and
relational degrees of freedom which are objectively observable and not
properties defined with respect to an external frame of reference. Shape
dynamics is not a very old field of study. Although it was already gradually
coming alive out of Julian Barbour's early works on Mach's Principle back in
the 1980s, it was invigorated by a series of rigorous works in the last decade.
This work is an exhaustive review of the historical and conceptual
underpinning of the theory that extends to Leibniz and Newton's philosophy, and
the currently established formulation of the theory, together with some of the
major results of its cosmological applications. The structure of this work
consists of two parts: In the first one we cover the foundations and the
formulation of the theory (both the field and particle ontology), and in the
second one we study its applications and reflect on the resolution of the
problem of the arrow of time. We end our journey by contemplating some recent
ideas and prospects for further developing the theory.
| [
{
"created": "Wed, 19 Jan 2022 04:39:20 GMT",
"version": "v1"
}
] | 2022-01-21 | [
[
"Farokhi",
"Pooya",
""
]
] | Shape dynamics is an alternative background-independent approach to classical dynamics that implements Leibnizian philosophy and Mach's Principles. It is a formulation of the dynamics of the universe in terms of the intrinsic and relational degrees of freedom which are objectively observable and not properties defined with respect to an external frame of reference. Shape dynamics is not a very old field of study. Although it was already gradually coming alive out of Julian Barbour's early works on Mach's Principle back in the 1980s, it was invigorated by a series of rigorous works in the last decade. This work is an exhaustive review of the historical and conceptual underpinning of the theory that extends to Leibniz and Newton's philosophy, and the currently established formulation of the theory, together with some of the major results of its cosmological applications. The structure of this work consists of two parts: In the first one we cover the foundations and the formulation of the theory (both the field and particle ontology), and in the second one we study its applications and reflect on the resolution of the problem of the arrow of time. We end our journey by contemplating some recent ideas and prospects for further developing the theory. |
0711.3041 | Peter Fritschel | The LIGO Scientific Collaboration: B. Abbott, et al | LIGO: The Laser Interferometer Gravitational-Wave Observatory | 50 pages, 14 figures | Rept.Prog.Phys.72:076901,2009 | 10.1088/0034-4885/72/7/076901 | LIGO-P070082-v4 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The goal of the Laser Interferometric Gravitational-Wave Observatory (LIGO)
is to detect and study gravitational waves of astrophysical origin. Direct
detection of gravitational waves holds the promise of testing general
relativity in the strong-field regime, of providing a new probe of exotic
objects such as black hole and neutron stars, and of uncovering unanticipated
new astrophysics. LIGO, a joint Caltech-MIT project supported by the National
Science Foundation, operates three multi-kilometer interferometers at two
widely separated sites in the United States. These detectors are the result of
decades of worldwide technology development, design, construction, and
commissioning. They are now operating at their design sensitivity, and are
sensitive to gravitational wave strains smaller than 1 part in 1E21. With this
unprecedented sensitivity, the data are being analyzed to detect or place
limits on gravitational waves from a variety of potential astrophysical
sources.
| [
{
"created": "Mon, 19 Nov 2007 23:15:31 GMT",
"version": "v1"
},
{
"created": "Tue, 19 May 2009 15:36:11 GMT",
"version": "v2"
}
] | 2009-09-29 | [
[
"The LIGO Scientific Collaboration",
"",
""
],
[
"Abbott",
"B.",
""
]
] | The goal of the Laser Interferometric Gravitational-Wave Observatory (LIGO) is to detect and study gravitational waves of astrophysical origin. Direct detection of gravitational waves holds the promise of testing general relativity in the strong-field regime, of providing a new probe of exotic objects such as black hole and neutron stars, and of uncovering unanticipated new astrophysics. LIGO, a joint Caltech-MIT project supported by the National Science Foundation, operates three multi-kilometer interferometers at two widely separated sites in the United States. These detectors are the result of decades of worldwide technology development, design, construction, and commissioning. They are now operating at their design sensitivity, and are sensitive to gravitational wave strains smaller than 1 part in 1E21. With this unprecedented sensitivity, the data are being analyzed to detect or place limits on gravitational waves from a variety of potential astrophysical sources. |
gr-qc/0606130 | Jiliang Jing | Shanxian Xu and Jiliang Jing | Energy of general 4-dimensional stationary axisymmetric spacetime in the
teleparallel geometry | 12 pages | Class.Quant.Grav. 23 (2006) 4659-4672 | 10.1088/0264-9381/23/14/007 | null | gr-qc hep-th | null | The field equation with the cosmological constant term is derived and the
energy of the general 4-dimensional stationary axisymmetric spacetime is
studied in the context of the hamiltonian formulation of the teleparallel
equivalent of general relativity (TEGR). We find that, by means of the integral
form of the constraints equations of the formalism naturally without any
restriction on the metric parameters, the energy for the asymptotically flat/de
Sitter/Anti-de Sitter stationary spacetimes in the Boyer-Lindquist coordinate
can be expressed as $E=\frac{1}{8\pi}\int_S d\theta d\phi(sin\theta
\sqrt{g_{\theta\theta}}+\sqrt{g_{\phi\phi}}-(1/\sqrt{g_{rr}})(\partial{\sqrt{g_
{\theta\theta} g_{\phi\phi}}}/\partial r))$. It is surprised to learn that the
energy expression is relevant to the metric components $g_{rr}$,
$g_{\theta\theta}$ and $g_{\phi\phi}$ only. As examples, by using this formula
we calculate the energies of the Kerr-Newman (KN), Kerr-Newman Anti-de Sitter
(KN-AdS), Kaluza-Klein, and Cveti\v{c}-Youm spacetimes.
| [
{
"created": "Fri, 30 Jun 2006 03:19:01 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Xu",
"Shanxian",
""
],
[
"Jing",
"Jiliang",
""
]
] | The field equation with the cosmological constant term is derived and the energy of the general 4-dimensional stationary axisymmetric spacetime is studied in the context of the hamiltonian formulation of the teleparallel equivalent of general relativity (TEGR). We find that, by means of the integral form of the constraints equations of the formalism naturally without any restriction on the metric parameters, the energy for the asymptotically flat/de Sitter/Anti-de Sitter stationary spacetimes in the Boyer-Lindquist coordinate can be expressed as $E=\frac{1}{8\pi}\int_S d\theta d\phi(sin\theta \sqrt{g_{\theta\theta}}+\sqrt{g_{\phi\phi}}-(1/\sqrt{g_{rr}})(\partial{\sqrt{g_ {\theta\theta} g_{\phi\phi}}}/\partial r))$. It is surprised to learn that the energy expression is relevant to the metric components $g_{rr}$, $g_{\theta\theta}$ and $g_{\phi\phi}$ only. As examples, by using this formula we calculate the energies of the Kerr-Newman (KN), Kerr-Newman Anti-de Sitter (KN-AdS), Kaluza-Klein, and Cveti\v{c}-Youm spacetimes. |
gr-qc/9903014 | Theodore Christopher Quinn | Theodore C. Quinn and Robert M. Wald | Energy conservation for point particles undergoing radiation reaction | 34 pages, 1 PostScript figure, uses RevTeX 3.1, submitted to PRD | Phys.Rev. D60 (1999) 064009 | 10.1103/PhysRevD.60.064009 | null | gr-qc | null | For smooth solutions to Maxwell's equations sourced by a smooth
charge-current distribution $j_a$ in stationary, asymptotically flat
spacetimes, one can prove an energy conservation theorem which asserts the
vanishing of the sum of (i) the difference between the final and initial
electromagnetic self-energy of the charge distribution, (ii) the net
electromagnetic energy radiated to infinity (and/or into a black hole/white
hole), and (iii) the total work done by the electromagnetic field on the charge
distribution via the Lorentz force. A similar conservation theorem can be
proven for linearized gravitational fields off of a stationary, asymptotically
flat background, with the second order Einstein tensor playing the role of an
effective stress-energy tensor of the linearized field. In this paper, we prove
the above theorems for smooth sources and then investigate the extent to which
they continue to hold for point particle sources. The ``self-energy'' of point
particles is ill defined, but in the electromagnetic case, we can consider
situations where, initially and finally, the point charges are stationary and
in the same spatial position, so that the self-energy terms should cancel.
Under certain assumptions concerning the decay behavior of source-free
solutions to Maxwell's equations, we prove the vanishing of the sum of the net
energy radiated to infinity and the net work done on the particle by the
DeWitt-Brehme radiation reaction force. We also obtain a similar conservation
theorem for angular momentum in an axisymmetric spacetime. In the gravitational
case, we argue that similar conservation results should hold for freely falling
point masses whose orbits begin and end at infinity.
| [
{
"created": "Thu, 4 Mar 1999 00:51:21 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Quinn",
"Theodore C.",
""
],
[
"Wald",
"Robert M.",
""
]
] | For smooth solutions to Maxwell's equations sourced by a smooth charge-current distribution $j_a$ in stationary, asymptotically flat spacetimes, one can prove an energy conservation theorem which asserts the vanishing of the sum of (i) the difference between the final and initial electromagnetic self-energy of the charge distribution, (ii) the net electromagnetic energy radiated to infinity (and/or into a black hole/white hole), and (iii) the total work done by the electromagnetic field on the charge distribution via the Lorentz force. A similar conservation theorem can be proven for linearized gravitational fields off of a stationary, asymptotically flat background, with the second order Einstein tensor playing the role of an effective stress-energy tensor of the linearized field. In this paper, we prove the above theorems for smooth sources and then investigate the extent to which they continue to hold for point particle sources. The ``self-energy'' of point particles is ill defined, but in the electromagnetic case, we can consider situations where, initially and finally, the point charges are stationary and in the same spatial position, so that the self-energy terms should cancel. Under certain assumptions concerning the decay behavior of source-free solutions to Maxwell's equations, we prove the vanishing of the sum of the net energy radiated to infinity and the net work done on the particle by the DeWitt-Brehme radiation reaction force. We also obtain a similar conservation theorem for angular momentum in an axisymmetric spacetime. In the gravitational case, we argue that similar conservation results should hold for freely falling point masses whose orbits begin and end at infinity. |
1707.02088 | Yannick Boetzel | Yannick Boetzel, Abhimanyu Susobhanan, Achamveedu Gopakumar, Antoine
Klein, Philippe Jetzer | Solving post-Newtonian accurate Kepler Equation | 20 pages, 4 figures | Phys. Rev. D 96, 044011 (2017) | 10.1103/PhysRevD.96.044011 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide an elegant way of solving analytically the third post-Newtonian
(3PN) accurate Kepler equation, associated with the 3PN-accurate generalized
quasi-Keplerian parametrization for compact binaries in eccentric orbits. An
additional analytic solution is presented to check the correctness of our
compact solution and we perform comparisons between our PN-accurate analytic
solution and a very accurate numerical solution of the PN-accurate Kepler
equation. We adapt our approach to compute crucial 3PN-accurate inputs that
will be required to compute analytically both the time and frequency domain
ready-to-use amplitude-corrected PN-accurate search templates for compact
binaries in inspiralling eccentric orbits.
| [
{
"created": "Fri, 7 Jul 2017 09:12:53 GMT",
"version": "v1"
},
{
"created": "Fri, 11 Aug 2017 12:38:52 GMT",
"version": "v2"
}
] | 2017-08-14 | [
[
"Boetzel",
"Yannick",
""
],
[
"Susobhanan",
"Abhimanyu",
""
],
[
"Gopakumar",
"Achamveedu",
""
],
[
"Klein",
"Antoine",
""
],
[
"Jetzer",
"Philippe",
""
]
] | We provide an elegant way of solving analytically the third post-Newtonian (3PN) accurate Kepler equation, associated with the 3PN-accurate generalized quasi-Keplerian parametrization for compact binaries in eccentric orbits. An additional analytic solution is presented to check the correctness of our compact solution and we perform comparisons between our PN-accurate analytic solution and a very accurate numerical solution of the PN-accurate Kepler equation. We adapt our approach to compute crucial 3PN-accurate inputs that will be required to compute analytically both the time and frequency domain ready-to-use amplitude-corrected PN-accurate search templates for compact binaries in inspiralling eccentric orbits. |
1908.04382 | Carlos O. Lousto | Carlos O. Lousto and James Healy | Kicking gravitational wave detectors with recoiling black holes | 10 pages, 6 figures | Phys. Rev. D 100, 104039 (2019) | 10.1103/PhysRevD.100.104039 | null | gr-qc astro-ph.CO astro-ph.GA | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Binary black holes emit gravitational radiation with net linear momentum
leading to a retreat of the final remnant black hole that can reach up to
$\sim5,000$ km/s. Full numerical relativity simulations are the only tool to
accurately compute these recoils since they are largely produced when the black
hole horizons are about to merge and they are strongly dependent on their spin
orientations at that moment. We present eight new numerical simulations of BBH
in the hangup-kick configuration family, leading to the maximum recoil. Black
holes are equal mass and near maximally spinning
($|\vec{S}_{1,2}|/m_{1,2}^2=0.97$). Depending on their phase at merger, this
family leads to $\sim\pm4,700$ km/s and all intermediate values of the recoil
along the orbital angular momentum of the binary system. We introduce a new
invariant method to evaluate the recoil dependence on the merger phase via the
waveform peak amplitude used as a reference phase angle and compare it with
previous definitions.
We also compute the mismatch between these hangup-kick waveforms to infer
their observable differentiability by gravitational wave detectors, such as
advanced LIGO, finding currently reachable signal-to-noise ratios, hence
allowing for the identification of highly recoiling black holes having
otherwise essentially the same binary parameters.
| [
{
"created": "Mon, 12 Aug 2019 21:03:11 GMT",
"version": "v1"
}
] | 2019-11-27 | [
[
"Lousto",
"Carlos O.",
""
],
[
"Healy",
"James",
""
]
] | Binary black holes emit gravitational radiation with net linear momentum leading to a retreat of the final remnant black hole that can reach up to $\sim5,000$ km/s. Full numerical relativity simulations are the only tool to accurately compute these recoils since they are largely produced when the black hole horizons are about to merge and they are strongly dependent on their spin orientations at that moment. We present eight new numerical simulations of BBH in the hangup-kick configuration family, leading to the maximum recoil. Black holes are equal mass and near maximally spinning ($|\vec{S}_{1,2}|/m_{1,2}^2=0.97$). Depending on their phase at merger, this family leads to $\sim\pm4,700$ km/s and all intermediate values of the recoil along the orbital angular momentum of the binary system. We introduce a new invariant method to evaluate the recoil dependence on the merger phase via the waveform peak amplitude used as a reference phase angle and compare it with previous definitions. We also compute the mismatch between these hangup-kick waveforms to infer their observable differentiability by gravitational wave detectors, such as advanced LIGO, finding currently reachable signal-to-noise ratios, hence allowing for the identification of highly recoiling black holes having otherwise essentially the same binary parameters. |
gr-qc/0202076 | Christopher Kohler | C. Kohler | Five-Dimensional Unification of the Cosmological Constant and the Photon
Mass | 8 pages, LaTeX | Class.Quant.Grav. 19 (2002) 3323-3332 | 10.1088/0264-9381/19/12/314 | null | gr-qc | null | Using a non-Riemannian geometry that is adapted to the 4+1 decomposition of
space-time in Kaluza-Klein theory, the translational part of the connection
form is related to the electromagnetic vector potential and a Stueckelberg
scalar. The consideration of a five-dimensional gravitational action functional
that shares the symmetries of the chosen geometry leads to a unification of the
four-dimensional cosmological term and a mass term for the vector potential.
| [
{
"created": "Thu, 21 Feb 2002 15:41:40 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Kohler",
"C.",
""
]
] | Using a non-Riemannian geometry that is adapted to the 4+1 decomposition of space-time in Kaluza-Klein theory, the translational part of the connection form is related to the electromagnetic vector potential and a Stueckelberg scalar. The consideration of a five-dimensional gravitational action functional that shares the symmetries of the chosen geometry leads to a unification of the four-dimensional cosmological term and a mass term for the vector potential. |
gr-qc/9502031 | Franz Hochfellner | W. Kummer and P. Widerin | Conserved Quasilocal Quantities and General Covariant Theories in Two
Dimensions | 21 pages, LaTeX-file | Phys.Rev. D52 (1995) 6965-6975 | 10.1103/PhysRevD.52.6965 | TUW-94-24 | gr-qc | null | General matterless--theories in 1+1 dimensions include dilaton gravity,
Yang--Mills theory as well as non--Einsteinian gravity with dynamical torsion
and higher power gravity, and even models of spherically symmetric d = 4
General Relativity. Their recent identification as special cases of
'Poisson--sigma--models' with simple general solution in an arbitrary gauge,
allows a comprehensive discussion of the relation between the known absolutely
conserved quantities in all those cases and Noether charges, resp. notions of
quasilocal 'energy--momentum'. In contrast to Noether like quantities,
quasilocal energy definitions require some sort of 'asymptotics' to allow an
interpretation as a (gauge--independent) observable. Dilaton gravitation,
although a little different in detail, shares this property with the other
cases. We also present a simple generalization of the absolute conservation law
for the case of interactions with matter of any type.
| [
{
"created": "Wed, 15 Feb 1995 22:07:50 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Kummer",
"W.",
""
],
[
"Widerin",
"P.",
""
]
] | General matterless--theories in 1+1 dimensions include dilaton gravity, Yang--Mills theory as well as non--Einsteinian gravity with dynamical torsion and higher power gravity, and even models of spherically symmetric d = 4 General Relativity. Their recent identification as special cases of 'Poisson--sigma--models' with simple general solution in an arbitrary gauge, allows a comprehensive discussion of the relation between the known absolutely conserved quantities in all those cases and Noether charges, resp. notions of quasilocal 'energy--momentum'. In contrast to Noether like quantities, quasilocal energy definitions require some sort of 'asymptotics' to allow an interpretation as a (gauge--independent) observable. Dilaton gravitation, although a little different in detail, shares this property with the other cases. We also present a simple generalization of the absolute conservation law for the case of interactions with matter of any type. |
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