id stringlengths 9 13 | submitter stringlengths 1 64 ⌀ | authors stringlengths 5 22.9k | title stringlengths 4 245 | comments stringlengths 1 548 ⌀ | journal-ref stringlengths 4 362 ⌀ | doi stringlengths 12 82 ⌀ | report-no stringlengths 2 281 ⌀ | categories stringclasses 793 values | license stringclasses 9 values | orig_abstract stringlengths 24 1.95k | versions listlengths 1 30 | update_date stringlengths 10 10 | authors_parsed listlengths 1 1.74k | abstract stringlengths 21 1.95k |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
gr-qc/0605088 | David Garfinkle | David Garfinkle | Inhomogeneous spacetimes as a dark energy model | 9 pages, 6 figures, Added References | Class.Quant.Grav. 23 (2006) 4811-4818 | 10.1088/0264-9381/23/15/002 | null | gr-qc astro-ph | null | Tolman-Bondi inhomogeneous spacetimes are used as a cosmological model for
type Ia supernova data. It is found that with certain parameter choices the
model fits the data as well as the standard $\Lambda$CDM cosmology does.
| [
{
"created": "Mon, 15 May 2006 16:44:24 GMT",
"version": "v1"
},
{
"created": "Mon, 22 May 2006 12:01:50 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Garfinkle",
"David",
""
]
] | Tolman-Bondi inhomogeneous spacetimes are used as a cosmological model for type Ia supernova data. It is found that with certain parameter choices the model fits the data as well as the standard $\Lambda$CDM cosmology does. |
gr-qc/0507040 | Igor Pe\~na | I. Pe\~na, C. Chryssomalakos, A. Corichi and D. Sudarsky | On the puzzle of Bremsstrahlung as described by coaccelerated observers | 29 pages, 1 figure; Revtex, minor changes, PACS corrected | Phys.Rev. D72 (2005) 084018 | 10.1103/PhysRevD.72.084018 | null | gr-qc hep-th | null | We consider anew some puzzling aspects of the equivalence of the quantum
field theoretical description of Bremsstrahlung from the inertial and
accelerated observer's perspectives. More concretely, we focus on the seemingly
paradoxical situation that arises when noting that the radiating source is in
thermal equilibrium with the thermal state of the quantum field in the wedge in
which it is located, and thus its presence does not change there the state of
the field, while it clearly does not affect the state of the field on the
opposite wedge. How then is the state of the quantum field on the future wedge
changed, as it must in order to account for the changed energy momentum tensor
there? This and related issues are carefully discussed.
| [
{
"created": "Sat, 9 Jul 2005 01:30:41 GMT",
"version": "v1"
},
{
"created": "Fri, 15 Jul 2005 19:43:36 GMT",
"version": "v2"
}
] | 2016-08-16 | [
[
"Peña",
"I.",
""
],
[
"Chryssomalakos",
"C.",
""
],
[
"Corichi",
"A.",
""
],
[
"Sudarsky",
"D.",
""
]
] | We consider anew some puzzling aspects of the equivalence of the quantum field theoretical description of Bremsstrahlung from the inertial and accelerated observer's perspectives. More concretely, we focus on the seemingly paradoxical situation that arises when noting that the radiating source is in thermal equilibrium with the thermal state of the quantum field in the wedge in which it is located, and thus its presence does not change there the state of the field, while it clearly does not affect the state of the field on the opposite wedge. How then is the state of the quantum field on the future wedge changed, as it must in order to account for the changed energy momentum tensor there? This and related issues are carefully discussed. |
gr-qc/0312098 | Sugumi Kanno | Sugumi Kanno, Jiro Soda | Effective Teukolsky Equation on the Brane | 2 pages, contribution to the Proceedings of the 6th RESCEU
International Symposium, Tokyo | null | null | null | gr-qc | null | To estimate Kaluza-Klein (KK) corrections on gravitational waves emitted by
perturbed rotating black strings, we give the effective Teukolsky equation on
the brane which is separable equation and hence numerically manageable.
| [
{
"created": "Mon, 22 Dec 2003 06:48:59 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Kanno",
"Sugumi",
""
],
[
"Soda",
"Jiro",
""
]
] | To estimate Kaluza-Klein (KK) corrections on gravitational waves emitted by perturbed rotating black strings, we give the effective Teukolsky equation on the brane which is separable equation and hence numerically manageable. |
0801.4942 | Sergiu Vacaru I. | Sergiu I. Vacaru | Loop Quantum Gravity in Ashtekar and Lagrange-Finsler Variables and
Fedosov Quantization of General Relativity | latex 2e, 11pt, 48 pages, 1 latex figure, discussion added | The Icfai Univ. J. Physics, 2 (2009) issue 4 | null | null | gr-qc hep-th math-ph math.MP | null | We propose an unified approach to loop quantum gravity and Fedosov
quantization of gravity following the geometry of double spacetime fibrations
and their quantum deformations. There are considered pseudo-Riemannian
manifolds enabled with 1) a nonholonomic 2+2 distribution defining a nonlinear
connection (N-connection) structure and 2) an Arnowitt-Deser-Misner 3+1
decomposition. The Ashtekar-Barbero variables are generalized and adapted to
the N-connection structure which allows us to write the general relativity
theory equivalently in terms of Lagrange-Finsler variables and related
canonical almost symplectic forms and connections. The Fedosov results are
re-defined for gravitational gauge like connections and there are analyzed the
conditions when the star product for deformation quantization is computed in
terms of geometric objects in loop quantum gravity. We speculate on equivalence
of quantum gravity theories with 3+1 and 2+2 splitting and quantum analogs of
the Einstein equations.
| [
{
"created": "Thu, 31 Jan 2008 18:30:15 GMT",
"version": "v1"
},
{
"created": "Sun, 10 Feb 2008 00:24:16 GMT",
"version": "v2"
}
] | 2009-11-21 | [
[
"Vacaru",
"Sergiu I.",
""
]
] | We propose an unified approach to loop quantum gravity and Fedosov quantization of gravity following the geometry of double spacetime fibrations and their quantum deformations. There are considered pseudo-Riemannian manifolds enabled with 1) a nonholonomic 2+2 distribution defining a nonlinear connection (N-connection) structure and 2) an Arnowitt-Deser-Misner 3+1 decomposition. The Ashtekar-Barbero variables are generalized and adapted to the N-connection structure which allows us to write the general relativity theory equivalently in terms of Lagrange-Finsler variables and related canonical almost symplectic forms and connections. The Fedosov results are re-defined for gravitational gauge like connections and there are analyzed the conditions when the star product for deformation quantization is computed in terms of geometric objects in loop quantum gravity. We speculate on equivalence of quantum gravity theories with 3+1 and 2+2 splitting and quantum analogs of the Einstein equations. |
0710.3808 | Andrew Lundgren | Andrew P. Lundgren, Ruxandra Bondarescu, David Tsang, Mihai Bondarescu | Finite Mirror Effects in Advanced Interferometric Gravitational Wave
Detectors | 13 pages, 12 figures, 4 tables. Referee input included and typos
fixed. Accepted by Phys. Rev. D | Phys.Rev.D77:042003,2008 | 10.1103/PhysRevD.77.042003 | null | gr-qc | null | Thermal noise is expected to be the dominant source of noise in the most
sensitive frequency band of second generation ground based gravitational wave
detectors. Reshaping the beam to a flatter wider profile which probes more of
the mirror surface reduces this noise. The "Mesa" beam shape has been proposed
for this purpose and was subsequently generalized to a family of hyperboloidal
beams with two parameters: twist angle alpha and beam width D. Varying alpha
allows a continuous transition from the nearly-flat to the nearly-concentric
Mesa beam configurations. We analytically prove that in the limit of infinite D
hyperboloidal beams become Gaussians. The Advanced LIGO diffraction loss design
constraint is 1 ppm per bounce. In the past the diffraction loss has often been
calculated using the clipping approximation that, in general, underestimates
the diffraction loss. We develop a code using pseudo-spectral methods to
compute the diffraction loss directly from the propagator. We find that the
diffraction loss is not a strictly monotonic function of beam width, but has
local minima that occur due to finite mirror effects and leads to natural
choices of D. For the Mesa beam a local minimum occurs at D = 10.67 cm and
leads to a diffraction loss of 1.4 ppm. We find that if one requires a
diffraction loss of strictly 1 ppm, the alpha = 0.91 pi hyperboloidal beam is
optimal, leading to the coating thermal noise being lower by about 10% than for
a Mesa beam while other types of thermal noise decrease as well. We then
develop an iterative process that reconstructs the mirror to specifically
account for finite mirror effects. This allows us to increase the D parameter
and lower the coating noise by about 30% compared to the original Mesa
configuration.
| [
{
"created": "Sun, 21 Oct 2007 21:40:16 GMT",
"version": "v1"
},
{
"created": "Sat, 15 Dec 2007 21:19:04 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Lundgren",
"Andrew P.",
""
],
[
"Bondarescu",
"Ruxandra",
""
],
[
"Tsang",
"David",
""
],
[
"Bondarescu",
"Mihai",
""
]
] | Thermal noise is expected to be the dominant source of noise in the most sensitive frequency band of second generation ground based gravitational wave detectors. Reshaping the beam to a flatter wider profile which probes more of the mirror surface reduces this noise. The "Mesa" beam shape has been proposed for this purpose and was subsequently generalized to a family of hyperboloidal beams with two parameters: twist angle alpha and beam width D. Varying alpha allows a continuous transition from the nearly-flat to the nearly-concentric Mesa beam configurations. We analytically prove that in the limit of infinite D hyperboloidal beams become Gaussians. The Advanced LIGO diffraction loss design constraint is 1 ppm per bounce. In the past the diffraction loss has often been calculated using the clipping approximation that, in general, underestimates the diffraction loss. We develop a code using pseudo-spectral methods to compute the diffraction loss directly from the propagator. We find that the diffraction loss is not a strictly monotonic function of beam width, but has local minima that occur due to finite mirror effects and leads to natural choices of D. For the Mesa beam a local minimum occurs at D = 10.67 cm and leads to a diffraction loss of 1.4 ppm. We find that if one requires a diffraction loss of strictly 1 ppm, the alpha = 0.91 pi hyperboloidal beam is optimal, leading to the coating thermal noise being lower by about 10% than for a Mesa beam while other types of thermal noise decrease as well. We then develop an iterative process that reconstructs the mirror to specifically account for finite mirror effects. This allows us to increase the D parameter and lower the coating noise by about 30% compared to the original Mesa configuration. |
gr-qc/0609046 | Hideaki Kudoh | Umpei Miyamoto and Hideaki Kudoh | New stable phase of non-uniform charged black strings | 27 pages, 5 figures, references and minor comments are added | JHEP0612:048,2006 | 10.1088/1126-6708/2006/12/048 | null | gr-qc hep-th | null | Non-uniform black strings coupled to a gauge field are constructed by a
perturbative method in a wide range of spacetime dimensions. At the linear
order of perturbations, we see that the Gregory-Laflamme instability vanishes
at the point where the background solution becomes thermodynamically stable.
The emergence/vanishing of the static mode resembles phase transitions, and in
fact we find that its critical exponent is nearly 1/2, which means a
second-order transition. By employing higher-order perturbations, the physical
properties of the non-uniform black strings are investigated in detail. For
fixed spacetime dimensions, we find the critical charges at which the stability
of non-uniform states changes. For some range of charge, non-uniform black
strings are entropically favored over uniform ones. The gauge charge works as a
control parameter that controls not only the stability of uniform black strings
but also the non-uniform states. In addition, we find that for a fixed
background charge the uniform state is not necessarily the state carrying the
largest tension. The phase diagram and a comparison with the critical dimension
are also discussed.
| [
{
"created": "Wed, 13 Sep 2006 20:00:33 GMT",
"version": "v1"
},
{
"created": "Sun, 26 Nov 2006 10:34:45 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Miyamoto",
"Umpei",
""
],
[
"Kudoh",
"Hideaki",
""
]
] | Non-uniform black strings coupled to a gauge field are constructed by a perturbative method in a wide range of spacetime dimensions. At the linear order of perturbations, we see that the Gregory-Laflamme instability vanishes at the point where the background solution becomes thermodynamically stable. The emergence/vanishing of the static mode resembles phase transitions, and in fact we find that its critical exponent is nearly 1/2, which means a second-order transition. By employing higher-order perturbations, the physical properties of the non-uniform black strings are investigated in detail. For fixed spacetime dimensions, we find the critical charges at which the stability of non-uniform states changes. For some range of charge, non-uniform black strings are entropically favored over uniform ones. The gauge charge works as a control parameter that controls not only the stability of uniform black strings but also the non-uniform states. In addition, we find that for a fixed background charge the uniform state is not necessarily the state carrying the largest tension. The phase diagram and a comparison with the critical dimension are also discussed. |
1703.10234 | Allen Stern | B. Harms and A. Stern | Growing Hair on the extremal $BTZ$ black hole | 11 pages, 1 figure, minor corrections included | null | 10.1016/j.physletb.2017.04.021 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that the nonlinear $\sigma-$model in an asymptotically $AdS_3$
space-time admits a novel local symmetry. The field action is assumed to be
quartic in the nonlinear $\sigma-$model fields and minimally coupled to
gravity. The local symmetry transformation simultaneously twists the nonlinear
$\sigma-$model fields and changes the space-time metric, and it can be used to
map an extremal $BTZ$ black hole to infinitely many hairy black hole solutions.
| [
{
"created": "Wed, 29 Mar 2017 20:21:58 GMT",
"version": "v1"
},
{
"created": "Wed, 19 Apr 2017 17:08:26 GMT",
"version": "v2"
}
] | 2017-04-26 | [
[
"Harms",
"B.",
""
],
[
"Stern",
"A.",
""
]
] | We show that the nonlinear $\sigma-$model in an asymptotically $AdS_3$ space-time admits a novel local symmetry. The field action is assumed to be quartic in the nonlinear $\sigma-$model fields and minimally coupled to gravity. The local symmetry transformation simultaneously twists the nonlinear $\sigma-$model fields and changes the space-time metric, and it can be used to map an extremal $BTZ$ black hole to infinitely many hairy black hole solutions. |
1207.4879 | Junko Ohashi | Junko Ohashi and Shinji Tsujikawa | Potential-driven Galileon inflation | 22 pages, 15 figures | JCAP 1210 (2012) 035 | 10.1088/1475-7516/2012/10/035 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | For the models of inflation driven by the potential energy of an inflaton
field $\phi$, the covariant Galileon Lagrangian $(\partial\phi)^2\Box \phi$
generally works to slow down the evolution of the field. On the other hand, if
the Galileon self-interaction is dominant relative to the standard kinetic
term, we show that there is no oscillatory regime of inflaton after the end of
inflation. This is typically accompanied by the appearance of the negative
propagation speed squared $c_s^2$ of a scalar mode, which leads to the
instability of small-scale perturbations. For chaotic inflation and natural
inflation we clarify the parameter space in which inflaton oscillates
coherently during reheating. Using the WMAP constraints of the scalar spectral
index and the tensor-to-scalar ratio as well, we find that the self coupling
$\lambda$ of the potential $V(\phi)=\lambda \phi^4/4$ is constrained to be very
much smaller than 1 and that the symmetry breaking scale $f$ of natural
inflation cannot be less than the reduced Planck mass $M_{\rm pl}$. We also
show that, in the presence of other covariant Galileon Lagrangians, there are
some cases in which inflaton oscillates coherently even for the self coupling
$\lambda$ of the order of 0.1, but still the instability associated with
negative $c_s^2$ is generally present.
| [
{
"created": "Fri, 20 Jul 2012 08:52:23 GMT",
"version": "v1"
},
{
"created": "Mon, 22 Oct 2012 10:41:58 GMT",
"version": "v2"
}
] | 2013-01-29 | [
[
"Ohashi",
"Junko",
""
],
[
"Tsujikawa",
"Shinji",
""
]
] | For the models of inflation driven by the potential energy of an inflaton field $\phi$, the covariant Galileon Lagrangian $(\partial\phi)^2\Box \phi$ generally works to slow down the evolution of the field. On the other hand, if the Galileon self-interaction is dominant relative to the standard kinetic term, we show that there is no oscillatory regime of inflaton after the end of inflation. This is typically accompanied by the appearance of the negative propagation speed squared $c_s^2$ of a scalar mode, which leads to the instability of small-scale perturbations. For chaotic inflation and natural inflation we clarify the parameter space in which inflaton oscillates coherently during reheating. Using the WMAP constraints of the scalar spectral index and the tensor-to-scalar ratio as well, we find that the self coupling $\lambda$ of the potential $V(\phi)=\lambda \phi^4/4$ is constrained to be very much smaller than 1 and that the symmetry breaking scale $f$ of natural inflation cannot be less than the reduced Planck mass $M_{\rm pl}$. We also show that, in the presence of other covariant Galileon Lagrangians, there are some cases in which inflaton oscillates coherently even for the self coupling $\lambda$ of the order of 0.1, but still the instability associated with negative $c_s^2$ is generally present. |
1410.1813 | Massimo Tinto | Massimo Tinto, Daniel DeBra, Sasha Buchman, Scott Tilley | gLISA: geosynchronous Laser Interferometer Space Antenna concepts with
off-the-shelf satellites | Paper submitted for publication to the journal: "Review of Scientific
Instruments". It is 13 pages long and contains 2 figures | null | 10.1063/1.4904862 | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss two geosynchronous gravitational wave mission concepts, which we
generically name gLISA. One relies on the science instrument hosting program
onboard geostationary commercial satellites, while the other takes advantage of
recent developments in the aerospace industry that result in dramatic satellite
and launching vehicle cost reductions for a dedicated geosynchronous mission.
To achieve the required level of disturbance free-fall onboard these large and
heavy platforms we propose a "two-stage" drag-free system, which incorporates
the Modular Gravitational Reference Sensor (MGRS) (developed at Stanford
University) and does not rely on the use of micro-Newton thrusters. Although
both mission concepts are characterized by different technical and programmatic
challenges, individually they could be flown and operated at a cost
significantly lower than those of previously envisioned gravitational wave
missions. We estimate both mission concepts to cost less than 500M US$ each,
and in the year 2015 we will perform at JPL a detailed selecting mission cost
analysis.
| [
{
"created": "Tue, 7 Oct 2014 17:39:44 GMT",
"version": "v1"
}
] | 2015-06-23 | [
[
"Tinto",
"Massimo",
""
],
[
"DeBra",
"Daniel",
""
],
[
"Buchman",
"Sasha",
""
],
[
"Tilley",
"Scott",
""
]
] | We discuss two geosynchronous gravitational wave mission concepts, which we generically name gLISA. One relies on the science instrument hosting program onboard geostationary commercial satellites, while the other takes advantage of recent developments in the aerospace industry that result in dramatic satellite and launching vehicle cost reductions for a dedicated geosynchronous mission. To achieve the required level of disturbance free-fall onboard these large and heavy platforms we propose a "two-stage" drag-free system, which incorporates the Modular Gravitational Reference Sensor (MGRS) (developed at Stanford University) and does not rely on the use of micro-Newton thrusters. Although both mission concepts are characterized by different technical and programmatic challenges, individually they could be flown and operated at a cost significantly lower than those of previously envisioned gravitational wave missions. We estimate both mission concepts to cost less than 500M US$ each, and in the year 2015 we will perform at JPL a detailed selecting mission cost analysis. |
0905.3292 | Thomas B\"ackdahl | Thomas B\"ackdahl | Relating the Newman-Penrose constants to the Geroch-Hansen multipole
moments | 8 pages, added references | Class.Quant.Grav.26:175021,2009 | 10.1088/0264-9381/26/17/175021 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we express the Newman--Penrose constants in terms of the
Geroch--Hansen multipole moments for stationary spacetimes. These expressions
are translation-invariant combinations of the multipole moments up to
quadrupole order, which do not normally vanish.
| [
{
"created": "Wed, 20 May 2009 12:55:59 GMT",
"version": "v1"
},
{
"created": "Tue, 25 Aug 2009 12:31:41 GMT",
"version": "v2"
}
] | 2009-09-28 | [
[
"Bäckdahl",
"Thomas",
""
]
] | In this paper, we express the Newman--Penrose constants in terms of the Geroch--Hansen multipole moments for stationary spacetimes. These expressions are translation-invariant combinations of the multipole moments up to quadrupole order, which do not normally vanish. |
2104.13649 | Andronikos Paliathanasis | Alex Giacomini, Esteban Gonz\'alez, Genly Leon and Andronikos
Paliathanasis | Variational symmetries and superintegrability in multifield cosmology | 34 pages, 13 figures, 2 tables | null | 10.1103/PhysRevD.105.044010 | null | gr-qc hep-ph math-ph math.MP | http://creativecommons.org/licenses/by/4.0/ | We consider a spatially flat Friedmann--Lema\^{\i}tre--Robertson--Walker
background space with an ideal gas and a multifield Lagrangian consisting of
two minimally coupled scalar fields which evolve in a field space of constant
curvature. For this cosmological model we classify the potential function for
the scalar fields such that variational point symmetries exist. The
corresponding conservation laws are calculated. Finally, analytic solutions are
presented for specific functional forms of the scalar field potential in which
the cosmological field equations are characterized as a Liouville integrable
system by point symmetries. The free parameters of the cosmological model are
constrained in order to describe analytic solutions for an inflationary epoch.
Finally, stability properties of exact closed-form solutions are investigated.
These solutions are scaling solutions with important physical properties for
the cosmological model.
| [
{
"created": "Wed, 28 Apr 2021 09:12:49 GMT",
"version": "v1"
}
] | 2022-02-23 | [
[
"Giacomini",
"Alex",
""
],
[
"González",
"Esteban",
""
],
[
"Leon",
"Genly",
""
],
[
"Paliathanasis",
"Andronikos",
""
]
] | We consider a spatially flat Friedmann--Lema\^{\i}tre--Robertson--Walker background space with an ideal gas and a multifield Lagrangian consisting of two minimally coupled scalar fields which evolve in a field space of constant curvature. For this cosmological model we classify the potential function for the scalar fields such that variational point symmetries exist. The corresponding conservation laws are calculated. Finally, analytic solutions are presented for specific functional forms of the scalar field potential in which the cosmological field equations are characterized as a Liouville integrable system by point symmetries. The free parameters of the cosmological model are constrained in order to describe analytic solutions for an inflationary epoch. Finally, stability properties of exact closed-form solutions are investigated. These solutions are scaling solutions with important physical properties for the cosmological model. |
gr-qc/9512013 | Szabados Laszlo | Laszlo B Szabados | Quasi-local energy-momentum and two-surface characterization of the
pp-wave spacetimes | 15 pages, Plain Tex, no figures | Class.Quant.Grav. 13 (1996) 1661-1678 | 10.1088/0264-9381/13/6/028 | -- | gr-qc | null | In the present paper the determination of the {\it pp}-wave metric form the
geometry of certain spacelike two-surfaces is considered. It has been shown
that the vanishing of the Dougan--Mason quasi-local mass $m_{\$}$, associated
with the smooth boundary $\$:=\partial\Sigma\approx S^2$ of a spacelike
hypersurface $\Sigma$, is equivalent to the statement that the Cauchy
development $D(\Sigma)$ is of a {\it pp}-wave type geometry with pure
radiation, provided the ingoing null normals are not diverging on $\$ $ and the
dominant energy condition holds on $D(\Sigma)$. The metric on $D(\Sigma)$
itself, however, has not been determined. Here, assuming that the matter is a
zero-rest-mass-field, it is shown that both the matter field and the {\it
pp}-wave metric of $D(\Sigma)$ are completely determined by the value of the
zero-rest-mass-field on $\$ $ and the two dimensional Sen--geometry of $\$ $
provided a convexity condition, slightly stronger than above, holds. Thus the
{\it pp}-waves can be characterized not only by the usual Cauchy data on a {\it
three} dimensional $\Sigma$ but by data on its {\it two} dimensional boundary
$\$ $ too. In addition, it is shown that the Ludvigsen--Vickers quasi-local
angular momentum of axially symmetric {\it pp}-wave geometries has the familiar
properties known for pure (matter) radiation.
| [
{
"created": "Wed, 6 Dec 1995 16:12:36 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Szabados",
"Laszlo B",
""
]
] | In the present paper the determination of the {\it pp}-wave metric form the geometry of certain spacelike two-surfaces is considered. It has been shown that the vanishing of the Dougan--Mason quasi-local mass $m_{\$}$, associated with the smooth boundary $\$:=\partial\Sigma\approx S^2$ of a spacelike hypersurface $\Sigma$, is equivalent to the statement that the Cauchy development $D(\Sigma)$ is of a {\it pp}-wave type geometry with pure radiation, provided the ingoing null normals are not diverging on $\$ $ and the dominant energy condition holds on $D(\Sigma)$. The metric on $D(\Sigma)$ itself, however, has not been determined. Here, assuming that the matter is a zero-rest-mass-field, it is shown that both the matter field and the {\it pp}-wave metric of $D(\Sigma)$ are completely determined by the value of the zero-rest-mass-field on $\$ $ and the two dimensional Sen--geometry of $\$ $ provided a convexity condition, slightly stronger than above, holds. Thus the {\it pp}-waves can be characterized not only by the usual Cauchy data on a {\it three} dimensional $\Sigma$ but by data on its {\it two} dimensional boundary $\$ $ too. In addition, it is shown that the Ludvigsen--Vickers quasi-local angular momentum of axially symmetric {\it pp}-wave geometries has the familiar properties known for pure (matter) radiation. |
1608.06218 | Paul Jefremov I. | Paul Jefremov and Volker Perlick | Circular motion in NUT space-time | 25 pages, 9 figures | Class. Quantum Grav. 33, 245014 (2016) | 10.1088/0264-9381/33/24/245014 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider circular motion in the NUT (Newman-Unti-Tamburino) space-time.
Among other things, we determine the location of circular time-like geodesic
orbits, in particular of the innermost stable circular orbit (ISCO) and of the
marginally bound circular orbit. Moreover, we discuss the von Zeipel cylinders
with respect to the stationary observers and with respect to the Zero Angular
Momentum Observers (ZAMOs). We also investigate the relation of von Zeipel
cylinders to inertial forces, in particular in the ultra-relativistic limit.
Finally, we generalise the construction of thick accretion tori ("Polish
doughnuts") which are well known on the Schwarzschild or Kerr background to the
case of the NUT metric. We argue that, in principle, a NUT source could be
distinguished from a Schwarzschild or Kerr source by observing the features of
circular matter flows in its neighbourhood.
| [
{
"created": "Thu, 18 Aug 2016 10:51:54 GMT",
"version": "v1"
}
] | 2017-05-09 | [
[
"Jefremov",
"Paul",
""
],
[
"Perlick",
"Volker",
""
]
] | We consider circular motion in the NUT (Newman-Unti-Tamburino) space-time. Among other things, we determine the location of circular time-like geodesic orbits, in particular of the innermost stable circular orbit (ISCO) and of the marginally bound circular orbit. Moreover, we discuss the von Zeipel cylinders with respect to the stationary observers and with respect to the Zero Angular Momentum Observers (ZAMOs). We also investigate the relation of von Zeipel cylinders to inertial forces, in particular in the ultra-relativistic limit. Finally, we generalise the construction of thick accretion tori ("Polish doughnuts") which are well known on the Schwarzschild or Kerr background to the case of the NUT metric. We argue that, in principle, a NUT source could be distinguished from a Schwarzschild or Kerr source by observing the features of circular matter flows in its neighbourhood. |
1701.01836 | Alexey Golovnev | Alexey Golovnev, Fedor Smirnov | Dealing with ghost-free massive gravity without explicit square roots of
matrices | 7 pages; minor changes, a few references added | Physics Letters B 770 (2017), 209 - 212 | 10.1016/j.physletb.2017.04.058 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we entertain a simple idea that the action of ghost free
massive gravity (in metric formulation) depends not on the full structure of
the square root of a matrix but rather on its invariants given by elementary
symmetric polynomials of the eigenvalues. In particular, we show how one can
construct the quadratic action around Minkowski spacetime without ever taking
the square root of the perturbed matrix. The method is however absolutely
generic. And it also contains full information on possible non-standard square
roots coming from intrinsic non-uniqueness of the procedure. In passing, we
mention some hard problems of those apocryphal square roots in the standard
approach which might be better tackled with our method. Futher details of the
latter are deferred to a separate paper.
| [
{
"created": "Sat, 7 Jan 2017 14:28:18 GMT",
"version": "v1"
},
{
"created": "Wed, 11 Jan 2017 15:31:25 GMT",
"version": "v2"
},
{
"created": "Fri, 21 Apr 2017 20:30:41 GMT",
"version": "v3"
}
] | 2017-06-15 | [
[
"Golovnev",
"Alexey",
""
],
[
"Smirnov",
"Fedor",
""
]
] | In this paper we entertain a simple idea that the action of ghost free massive gravity (in metric formulation) depends not on the full structure of the square root of a matrix but rather on its invariants given by elementary symmetric polynomials of the eigenvalues. In particular, we show how one can construct the quadratic action around Minkowski spacetime without ever taking the square root of the perturbed matrix. The method is however absolutely generic. And it also contains full information on possible non-standard square roots coming from intrinsic non-uniqueness of the procedure. In passing, we mention some hard problems of those apocryphal square roots in the standard approach which might be better tackled with our method. Futher details of the latter are deferred to a separate paper. |
1712.07574 | Khalid Saifullah | Jamil Ahmed and K. Saifullah | Greybody factor of scalar fields from black strings | null | Eur. Phys. J. C (2017) 77: 885 | 10.1140/epjc/s10052-017-5449-6 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The greybody factor of massless, uncharged scalar fields is studied in the
background of cylindrically symmetric spacetimes, in the low-energy
approximation. We discuss two cases. In the first case we derive analytical
expression for the absorption probability when the spacetime is kinetically
coupled with the Einstein tensor. In the second case we do the analysis in the
absence of the coupling constant. For this purpose we analyze the wave equation
which is obtained from Klein-Gordon equation. The radial part of the wave
equation is solved in the form of the hypergeometric function in the near
horizon region, whereas in the far region the solution is of the form of
Bessel's function. Finally, considering continuity of the wave function we
smoothly match the two solutions in the low energy approximation to get the
formula for the absorption probability.
| [
{
"created": "Wed, 20 Dec 2017 16:49:45 GMT",
"version": "v1"
}
] | 2018-01-17 | [
[
"Ahmed",
"Jamil",
""
],
[
"Saifullah",
"K.",
""
]
] | The greybody factor of massless, uncharged scalar fields is studied in the background of cylindrically symmetric spacetimes, in the low-energy approximation. We discuss two cases. In the first case we derive analytical expression for the absorption probability when the spacetime is kinetically coupled with the Einstein tensor. In the second case we do the analysis in the absence of the coupling constant. For this purpose we analyze the wave equation which is obtained from Klein-Gordon equation. The radial part of the wave equation is solved in the form of the hypergeometric function in the near horizon region, whereas in the far region the solution is of the form of Bessel's function. Finally, considering continuity of the wave function we smoothly match the two solutions in the low energy approximation to get the formula for the absorption probability. |
1705.07515 | Michele Levi | Michele Levi | Effective Field Theory of Post-Newtonian Gravity Including Spins | 5 pages, published | Proceedings of the 52nd Rencontres de Moriond 2017 Gravitation
(2017) 263 | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present in detail an Effective Field Theory (EFT) formulation for the
essential case of spinning objects as the components of inspiralling compact
binaries. We review its implementation, carried out in a series of works in
recent years, which leveled the high post-Newtonian (PN) accuracy in the
spinning sector to that, recently attained in the non-spinning sector. We note
a public package, "EFTofPNG", that we recently created for high precision
computation in the EFT of PN Gravity, which covers all sectors, and includes an
observables pipeline.
| [
{
"created": "Sun, 21 May 2017 22:20:47 GMT",
"version": "v1"
},
{
"created": "Thu, 30 Nov 2017 15:11:30 GMT",
"version": "v2"
},
{
"created": "Wed, 26 Sep 2018 00:54:33 GMT",
"version": "v3"
}
] | 2018-09-27 | [
[
"Levi",
"Michele",
""
]
] | We present in detail an Effective Field Theory (EFT) formulation for the essential case of spinning objects as the components of inspiralling compact binaries. We review its implementation, carried out in a series of works in recent years, which leveled the high post-Newtonian (PN) accuracy in the spinning sector to that, recently attained in the non-spinning sector. We note a public package, "EFTofPNG", that we recently created for high precision computation in the EFT of PN Gravity, which covers all sectors, and includes an observables pipeline. |
1603.08180 | Francisco Lobo | Francisco Cabral and Francisco S. N. Lobo | Electrodynamics and spacetime geometry: Astrophysical applications | 20 pages. Applications of the general formalism developed in
arXiv:1602.01492. V2: typos corrected and references added. V3: 15 pages;
revised version to appear in The European Physical Journal Plus | Eur. Phys. J. Plus (2017) 132: 304 | 10.1140/epjp/i2017-11618-2 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | After a brief review of the foundations of (pre-metric) electromagnetism, we
explore some physical consequences of electrodynamics in curved spacetime. In
general, new electromagnetic couplings and related phenomena are induced by the
spacetime curvature. The applications of astrophysical interest considered here
correspond essentially to the following geometries: the Schwarzschild spacetime
and the spacetime around a rotating spherical mass in the weak field and slow
rotation regime. In the latter, we use the Parameterised Post-Newtonian (PPN)
formalism. We also explore the hypothesis that the electric and magnetic
properties of vacuum reflect the spacetime isometries. Therefore, the
permittivity and permeability tensors should not be considered homogeneous and
isotropic a priori. For spherical geometries we consider the effect of relaxing
the homogeneity assumption in the constitutive relations between the fields and
excitations. This affects the generalized Gauss and Maxwell-Amp\`{e}re laws
where the electric permittivity and magnetic permeability in vacuum depend on
the radial coordinate in accordance with the local isometries of space. For the
axially symmetric geometries we relax both the assumptions of homogeneity and
isotropy. We explore simple solutions and discuss the physical implications
related to different phenomena such as: the decay of electromagnetic fields in
the presence of gravity, magnetic terms in Gauss law due to the
gravitomagnetism of the spacetime around rotating objects, a frame-dragging
effect on electric fields and the possibility of a spatial (radial) variability
of the velocity of light in vacuum around spherical astrophysical objects for
strong gravitational fields.
| [
{
"created": "Sun, 27 Mar 2016 06:33:43 GMT",
"version": "v1"
},
{
"created": "Fri, 22 Apr 2016 16:00:56 GMT",
"version": "v2"
},
{
"created": "Thu, 1 Jun 2017 16:27:26 GMT",
"version": "v3"
}
] | 2017-07-11 | [
[
"Cabral",
"Francisco",
""
],
[
"Lobo",
"Francisco S. N.",
""
]
] | After a brief review of the foundations of (pre-metric) electromagnetism, we explore some physical consequences of electrodynamics in curved spacetime. In general, new electromagnetic couplings and related phenomena are induced by the spacetime curvature. The applications of astrophysical interest considered here correspond essentially to the following geometries: the Schwarzschild spacetime and the spacetime around a rotating spherical mass in the weak field and slow rotation regime. In the latter, we use the Parameterised Post-Newtonian (PPN) formalism. We also explore the hypothesis that the electric and magnetic properties of vacuum reflect the spacetime isometries. Therefore, the permittivity and permeability tensors should not be considered homogeneous and isotropic a priori. For spherical geometries we consider the effect of relaxing the homogeneity assumption in the constitutive relations between the fields and excitations. This affects the generalized Gauss and Maxwell-Amp\`{e}re laws where the electric permittivity and magnetic permeability in vacuum depend on the radial coordinate in accordance with the local isometries of space. For the axially symmetric geometries we relax both the assumptions of homogeneity and isotropy. We explore simple solutions and discuss the physical implications related to different phenomena such as: the decay of electromagnetic fields in the presence of gravity, magnetic terms in Gauss law due to the gravitomagnetism of the spacetime around rotating objects, a frame-dragging effect on electric fields and the possibility of a spatial (radial) variability of the velocity of light in vacuum around spherical astrophysical objects for strong gravitational fields. |
1901.01176 | Alberto Saa | Hengameh R. Dehkordi and Alberto Saa | Huygens' envelope principle in Finsler spaces and analogue gravity | 17 pages, 3 figures. Final version accepted for publication in CQG.
Animations in Supplementary Material available at
http://vigo.ime.unicamp.br/Huygens/ | Class. Quantum Grav. 36, 085008 (2019) | 10.1088/1361-6382/ab0f03 | null | gr-qc math-ph math.DG math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We extend to the $n$-dimensional case a recent theorem establishing the
validity of the Huygens' envelope principle for wavefronts in Finsler spaces.
Our results have direct applications in analogue gravity models, for which the
Fermat's principle of least time naturally gives origin to an underlying
Finslerian geometry. For the sake of illustration, we consider two explicit
examples motivated by recent experimental results: surface waves in flumes and
vortices. For both examples, we have distinctive directional spacetime
structures, namely horizons and ergospheres, respectively. We show that both
structures are associated with certain directional divergences in the
underlying Finslerian (Randers) geometry. Our results show that Finsler
geometry may provide a fresh view on the causal structure of spacetime, not
only in analogue models but also for General Relativity.
| [
{
"created": "Fri, 4 Jan 2019 15:31:48 GMT",
"version": "v1"
},
{
"created": "Wed, 6 Mar 2019 16:16:00 GMT",
"version": "v2"
}
] | 2019-04-04 | [
[
"Dehkordi",
"Hengameh R.",
""
],
[
"Saa",
"Alberto",
""
]
] | We extend to the $n$-dimensional case a recent theorem establishing the validity of the Huygens' envelope principle for wavefronts in Finsler spaces. Our results have direct applications in analogue gravity models, for which the Fermat's principle of least time naturally gives origin to an underlying Finslerian geometry. For the sake of illustration, we consider two explicit examples motivated by recent experimental results: surface waves in flumes and vortices. For both examples, we have distinctive directional spacetime structures, namely horizons and ergospheres, respectively. We show that both structures are associated with certain directional divergences in the underlying Finslerian (Randers) geometry. Our results show that Finsler geometry may provide a fresh view on the causal structure of spacetime, not only in analogue models but also for General Relativity. |
2002.11658 | Marco de Cesare | Marco de Cesare, Sanjeev S. Seahra, Edward Wilson-Ewing | The singularity in mimetic Kantowski-Sachs cosmology | 24 pages + appendices and references, 10 figures; v2: matches version
accepted for publication in JCAP | JCAP 07 (2020) 018 | 10.1088/1475-7516/2020/07/018 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The dynamics of the vacuum Kantowski-Sachs space-time are studied in the
so-called limiting curvature mimetic gravity theory. It is shown that in this
theory the vacuum Kantowski-Sachs space-time is always singular. While the
departures from general relativity due to the limiting curvature mimetic theory
do provide an upper bound on the magnitude of the expansion scalar, both its
rate of oscillations and the magnitude of the directional Hubble rates increase
without bound and cause curvature invariants to diverge. Also, since the radial
scale factor does not vanish in finite (past) time, in this particular theory
the Kantowski-Sachs space-time cannot be matched to a null black hole event
horizon and, therefore, does not correspond to the interior of a static and
spherically symmetric black hole.
| [
{
"created": "Wed, 26 Feb 2020 17:37:26 GMT",
"version": "v1"
},
{
"created": "Wed, 17 Jun 2020 00:14:03 GMT",
"version": "v2"
}
] | 2020-07-08 | [
[
"de Cesare",
"Marco",
""
],
[
"Seahra",
"Sanjeev S.",
""
],
[
"Wilson-Ewing",
"Edward",
""
]
] | The dynamics of the vacuum Kantowski-Sachs space-time are studied in the so-called limiting curvature mimetic gravity theory. It is shown that in this theory the vacuum Kantowski-Sachs space-time is always singular. While the departures from general relativity due to the limiting curvature mimetic theory do provide an upper bound on the magnitude of the expansion scalar, both its rate of oscillations and the magnitude of the directional Hubble rates increase without bound and cause curvature invariants to diverge. Also, since the radial scale factor does not vanish in finite (past) time, in this particular theory the Kantowski-Sachs space-time cannot be matched to a null black hole event horizon and, therefore, does not correspond to the interior of a static and spherically symmetric black hole. |
2406.11724 | Tieguang Zi | Tieguang Zi and Chao Zhang | Detecting the massive vector field with extreme mass-ratio inspirals | 14 pages,5 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by-sa/4.0/ | The future space-borne gravitational wave detector, Laser Interferometer
Space Antenna (LISA), has the potential of detecting the fundamental fields,
such as the charge and mass ultra-light scalar field. In this paper we study
the effect of lighter vector field on the gravitational waveforms from extreme
mass-ratio inspirals (EMRI) system, consisting of a stellar-mass object and the
massive black hole (MBH) in the Einstein-Proca theory of a massive vector field
coupling to gravity. Using the perturbation theory, we compute the energy
fluxes including the contributions of the Proca field and the gravitational
field, then obtain the adiabatic inspiraling orbits and corresponding
waveforms. Our results demonstrate that the vector charge and mass carried by
the secondary body lead to detectable effects on EMRI waveform, and LISA has
the potential to measure the mass of the Proca field with greater precision.
| [
{
"created": "Mon, 17 Jun 2024 16:41:25 GMT",
"version": "v1"
}
] | 2024-06-18 | [
[
"Zi",
"Tieguang",
""
],
[
"Zhang",
"Chao",
""
]
] | The future space-borne gravitational wave detector, Laser Interferometer Space Antenna (LISA), has the potential of detecting the fundamental fields, such as the charge and mass ultra-light scalar field. In this paper we study the effect of lighter vector field on the gravitational waveforms from extreme mass-ratio inspirals (EMRI) system, consisting of a stellar-mass object and the massive black hole (MBH) in the Einstein-Proca theory of a massive vector field coupling to gravity. Using the perturbation theory, we compute the energy fluxes including the contributions of the Proca field and the gravitational field, then obtain the adiabatic inspiraling orbits and corresponding waveforms. Our results demonstrate that the vector charge and mass carried by the secondary body lead to detectable effects on EMRI waveform, and LISA has the potential to measure the mass of the Proca field with greater precision. |
gr-qc/9912053 | Anjan Ananda Sen | A.A.Sen | Vacuumless cosmic strings in Brans-Dicke theory | 10 pages, Latex, some errors are corrected, new conclusions and
references added | Int.J.Mod.Phys. D10 (2001) 515-522 | 10.1142/S0218271801000986 | null | gr-qc | null | The gravitational fields of vacuumless global and gauge strings have been
studied in Brans-Dicke theory under the weak field assumption of the field
equations. It has been shown that both global and gauge string can have
repulsive as well as attractive gravitational effect in Brans-Dicke theory
which is not so in General Relativity.
| [
{
"created": "Tue, 14 Dec 1999 14:57:25 GMT",
"version": "v1"
},
{
"created": "Sun, 13 Feb 2000 17:47:32 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Sen",
"A. A.",
""
]
] | The gravitational fields of vacuumless global and gauge strings have been studied in Brans-Dicke theory under the weak field assumption of the field equations. It has been shown that both global and gauge string can have repulsive as well as attractive gravitational effect in Brans-Dicke theory which is not so in General Relativity. |
0708.0734 | Ion I. Cot{\ba}escu | Ion I. Cotaescu | The Schr\" odinger picture of the Dirac quantum mechanics on spatially
flat Robertson-Walker backgrounds | 6 pages 0 figures | null | 10.1142/S0217732307026035 | null | gr-qc math-ph math.MP quant-ph | null | The Schr\" odinger picture of the Dirac quantum mechanics is defined in
charts with spatially flat Robertson-Walker metrics and Cartesian coordinates.
The main observables of this picture are identified, including the interacting
part of the Hamiltonian operator produced by the minimal coupling with the
gravitational field. It is shown that in this approach new Dirac quantum modes
on de Sitter spacetimes may be found analytically solving the Dirac equation.
| [
{
"created": "Mon, 6 Aug 2007 10:00:25 GMT",
"version": "v1"
}
] | 2014-10-07 | [
[
"Cotaescu",
"Ion I.",
""
]
] | The Schr\" odinger picture of the Dirac quantum mechanics is defined in charts with spatially flat Robertson-Walker metrics and Cartesian coordinates. The main observables of this picture are identified, including the interacting part of the Hamiltonian operator produced by the minimal coupling with the gravitational field. It is shown that in this approach new Dirac quantum modes on de Sitter spacetimes may be found analytically solving the Dirac equation. |
1710.01818 | Shahram Panahiyan | S. H. Hendi, N. Riazi, S. Panahiyan, B. Eslam Panah | Higher dimensional dyonic black holes | 27 pages, 9 figures, Comments are welcomed | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The paper at hand presents a novel class of dyonic black holes in higher
dimensions through a new proposal for the electromagnetic field tensor. The
black hole solutions are extracted analytically and their geometrical/physical
properties are studied. In addition, the details regarding thermodynamical
structure and phase transition behavior of the solutions for $4$ different
cases are investigated: i) general case, ii) constant electric field, iii)
constant magnetic field, and iv) constant electric and magnetic fields. It will
be shown that depending on the picture under consideration, the thermodynamical
properties are modified. To have better picture regarding the phase
transitions, the concept of the extended phase space is employed. It will be
shown that in the absence of the electric field, magnetic black holes present
van der Waals like phase transition. Furthermore, it will be highlighted that
for super magnetized black holes, no phase transition exists.
| [
{
"created": "Wed, 4 Oct 2017 22:19:58 GMT",
"version": "v1"
}
] | 2017-10-06 | [
[
"Hendi",
"S. H.",
""
],
[
"Riazi",
"N.",
""
],
[
"Panahiyan",
"S.",
""
],
[
"Panah",
"B. Eslam",
""
]
] | The paper at hand presents a novel class of dyonic black holes in higher dimensions through a new proposal for the electromagnetic field tensor. The black hole solutions are extracted analytically and their geometrical/physical properties are studied. In addition, the details regarding thermodynamical structure and phase transition behavior of the solutions for $4$ different cases are investigated: i) general case, ii) constant electric field, iii) constant magnetic field, and iv) constant electric and magnetic fields. It will be shown that depending on the picture under consideration, the thermodynamical properties are modified. To have better picture regarding the phase transitions, the concept of the extended phase space is employed. It will be shown that in the absence of the electric field, magnetic black holes present van der Waals like phase transition. Furthermore, it will be highlighted that for super magnetized black holes, no phase transition exists. |
gr-qc/0206033 | Robert D. Klauber | Robert D. Klauber | Derivation of the General Case Sagnac Result using Non-time-orthogonal
Analysis | revised to include changes from pre-publication review; 11 pages
including 3 figures, 4 appendices and references | Found.Phys.Lett. 16 (2003) 447-463 | 10.1023/B:FOPL.0000012776.04871.6d | null | gr-qc | null | The experimentally determined Sagnac fringe shift dependency on angular
velocity and enclosed area is derived from the rotating reference frame using
non-time-orthogonal tensor analysis. The relationship for the most general
case, in which the area enclosed is not circular and does not have the axis of
rotation passing through its center, is determined. It is submitted that this
quantitative result, along with a related thought experiment, can not be found
using the conventional approach of local co-moving Lorentz frames.
| [
{
"created": "Wed, 12 Jun 2002 17:14:44 GMT",
"version": "v1"
},
{
"created": "Sun, 9 Nov 2003 18:37:48 GMT",
"version": "v2"
}
] | 2009-11-07 | [
[
"Klauber",
"Robert D.",
""
]
] | The experimentally determined Sagnac fringe shift dependency on angular velocity and enclosed area is derived from the rotating reference frame using non-time-orthogonal tensor analysis. The relationship for the most general case, in which the area enclosed is not circular and does not have the axis of rotation passing through its center, is determined. It is submitted that this quantitative result, along with a related thought experiment, can not be found using the conventional approach of local co-moving Lorentz frames. |
2203.11557 | Vikramaditya Mondal | Vikramaditya Mondal | Wave function of the universe in the presence of trans-Planckian
censorship | null | JCAP08(2022)005 | 10.1088/1475-7516/2022/08/005 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The wave function for a closed de Sitter universe has been computed,
demanding consistency with the recently proposed Trans-Planckian Censorship
Conjecture (TCC). We extend the Einstein-Hilbert action to contain a
complex-valued term which provides an exponentially decaying weight for the
geometries violating TCC in the Lorentzian path integral sum while working in
the minisuperspace approach to quantum cosmology. This \textit{postulated}
modification suppresses the probability of evolution of the universe into
configurations that violate TCC. We show that due to the presence of this
suppression factor, the Hubble rate of the universe at the end of the inflation
gets subdued and assumes a value less than what is expected classically.
Moreover, the consequences of this quantum gravity motivated correction in the
primordial power spectrum are discussed as well.
| [
{
"created": "Tue, 22 Mar 2022 09:28:43 GMT",
"version": "v1"
},
{
"created": "Mon, 20 Jun 2022 09:49:09 GMT",
"version": "v2"
}
] | 2022-08-09 | [
[
"Mondal",
"Vikramaditya",
""
]
] | The wave function for a closed de Sitter universe has been computed, demanding consistency with the recently proposed Trans-Planckian Censorship Conjecture (TCC). We extend the Einstein-Hilbert action to contain a complex-valued term which provides an exponentially decaying weight for the geometries violating TCC in the Lorentzian path integral sum while working in the minisuperspace approach to quantum cosmology. This \textit{postulated} modification suppresses the probability of evolution of the universe into configurations that violate TCC. We show that due to the presence of this suppression factor, the Hubble rate of the universe at the end of the inflation gets subdued and assumes a value less than what is expected classically. Moreover, the consequences of this quantum gravity motivated correction in the primordial power spectrum are discussed as well. |
2308.00865 | Tahereh Azizi | Tahereh Azizi, Najibe Borhani, and Mojtaba Haghshenas | Evolution of Gravitational Waves in Non-minimal Coupling Between
Geometry and Matter Theories of Gravity | 26 pages, 22 figures; to appear in Physics of the Dark Universe | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider some specific models of non-minimal matter-geometry coupling
theories and investigate the propagation of the gravitational waves in them.
Extracting the temporal evolution of the gravitational wave equation within the
framework of a flat FRW universe with a perfect fluid distribution, we analyze
the waveforms traveling during the time. We find that while both the amplitude
and frequency of the GWs decay with time in all considered models, the rate of
reduction is highly sensitive to the values of the equation of state parameter
and input parameters of the considered models.
| [
{
"created": "Tue, 1 Aug 2023 22:28:18 GMT",
"version": "v1"
}
] | 2023-08-03 | [
[
"Azizi",
"Tahereh",
""
],
[
"Borhani",
"Najibe",
""
],
[
"Haghshenas",
"Mojtaba",
""
]
] | We consider some specific models of non-minimal matter-geometry coupling theories and investigate the propagation of the gravitational waves in them. Extracting the temporal evolution of the gravitational wave equation within the framework of a flat FRW universe with a perfect fluid distribution, we analyze the waveforms traveling during the time. We find that while both the amplitude and frequency of the GWs decay with time in all considered models, the rate of reduction is highly sensitive to the values of the equation of state parameter and input parameters of the considered models. |
0902.1487 | Jeferson Oliveira de | Owen Pavel Fernandez Piedra, Jeferson de Oliveira | Vacuum polarization effects on quasinormal modes in electrically charged
black hole spacetimes | 9 pages, 5 figures, typos added, references added and content changed | Int.J.Mod.Phys.D19:63-78,2010 | 10.1142/S0218271810016257 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the influence of vacuum polarization of quantum massive fields
on the scalar sector of quasinormal modes in spherically symmetric black holes.
We consider the evolution of a massless scalar field on the spacetime
corresponding to a charged semiclassical black hole, consisting of the quantum
corrected geometry of a Reissner-Nordstr\"om black hole dressed by a quantum
massive scalar field in the large mass limit. Using a sixth order WKB approach
we find the shift in the quasinormal mode frequencies due to vacuum
polarization .
| [
{
"created": "Mon, 9 Feb 2009 18:08:01 GMT",
"version": "v1"
},
{
"created": "Fri, 27 Feb 2009 14:00:40 GMT",
"version": "v2"
},
{
"created": "Tue, 11 Aug 2009 13:39:12 GMT",
"version": "v3"
},
{
"created": "Fri, 12 Feb 2010 17:42:46 GMT",
"version": "v4"
}
] | 2011-07-19 | [
[
"Piedra",
"Owen Pavel Fernandez",
""
],
[
"de Oliveira",
"Jeferson",
""
]
] | We investigate the influence of vacuum polarization of quantum massive fields on the scalar sector of quasinormal modes in spherically symmetric black holes. We consider the evolution of a massless scalar field on the spacetime corresponding to a charged semiclassical black hole, consisting of the quantum corrected geometry of a Reissner-Nordstr\"om black hole dressed by a quantum massive scalar field in the large mass limit. Using a sixth order WKB approach we find the shift in the quasinormal mode frequencies due to vacuum polarization . |
gr-qc/0701148 | Jordan Camp | Jordan B. Camp, John K. Cannizzo, Kenji Numata | Application of the Hilbert-Huang Transform to the Search for
Gravitational Waves | null | Phys.Rev.D75:061101,2007 | 10.1103/PhysRevD.75.061101 | null | gr-qc | null | We present the application of a novel method of time-series analysis, the
Hilbert-Huang Transform, to the search for gravitational waves. This algorithm
is adaptive and does not impose a basis set on the data, and thus the
time-frequency decomposition it provides is not limited by time-frequency
uncertainty spreading. Because of its high time-frequency resolution it has
important applications to both signal detection and instrumental
characterization. Applications to the data analysis of the ground and space
based gravitational wave detectors, LIGO and LISA, are described.
| [
{
"created": "Sat, 27 Jan 2007 16:10:31 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Camp",
"Jordan B.",
""
],
[
"Cannizzo",
"John K.",
""
],
[
"Numata",
"Kenji",
""
]
] | We present the application of a novel method of time-series analysis, the Hilbert-Huang Transform, to the search for gravitational waves. This algorithm is adaptive and does not impose a basis set on the data, and thus the time-frequency decomposition it provides is not limited by time-frequency uncertainty spreading. Because of its high time-frequency resolution it has important applications to both signal detection and instrumental characterization. Applications to the data analysis of the ground and space based gravitational wave detectors, LIGO and LISA, are described. |
2008.07697 | Nomaan X | Sumati Surya, Nomaan X and Yasaman K. Yazdi | Entanglement Entropy of Causal Set de Sitter Horizons | 30 pages, 16 figures | Class. Quantum Grav. 38 115001 (2021) | 10.1088/1361-6382/abf279 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | de Sitter cosmological horizons are known to exhibit thermodynamic properties
similar to black hole horizons. In this work we study causal set de Sitter
horizons, using Sorkin's spacetime entanglement entropy (SSEE) formula, for a
conformally coupled quantum scalar field. We calculate the causal set SSEE for
the Rindler-like wedge of a symmetric slab of de Sitter spacetime in $d=2,4$
spacetime dimensions using the Sorkin-Johnston vacuum state. We find that the
SSEE obeys an area law when the spectrum of the Pauli-Jordan operator is
appropriately truncated in both the de Sitter slab as well as its restriction
to the Rindler-like wedge. Without this truncation, the SSEE satisfies a volume
law. This is in agreement with Sorkin and Yazdi's calculations for the causal
set SSEE for nested causal diamonds in $\mathbb{M}^2$, where they showed that
an area law is obtained only after truncating the Pauli-Jordan spectrum. In
this work we explore different truncation schemes with the criterion that the
SSEE so obtained obeys an area law.
| [
{
"created": "Tue, 18 Aug 2020 02:07:26 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Mar 2021 13:38:58 GMT",
"version": "v2"
}
] | 2023-11-27 | [
[
"Surya",
"Sumati",
""
],
[
"X",
"Nomaan",
""
],
[
"Yazdi",
"Yasaman K.",
""
]
] | de Sitter cosmological horizons are known to exhibit thermodynamic properties similar to black hole horizons. In this work we study causal set de Sitter horizons, using Sorkin's spacetime entanglement entropy (SSEE) formula, for a conformally coupled quantum scalar field. We calculate the causal set SSEE for the Rindler-like wedge of a symmetric slab of de Sitter spacetime in $d=2,4$ spacetime dimensions using the Sorkin-Johnston vacuum state. We find that the SSEE obeys an area law when the spectrum of the Pauli-Jordan operator is appropriately truncated in both the de Sitter slab as well as its restriction to the Rindler-like wedge. Without this truncation, the SSEE satisfies a volume law. This is in agreement with Sorkin and Yazdi's calculations for the causal set SSEE for nested causal diamonds in $\mathbb{M}^2$, where they showed that an area law is obtained only after truncating the Pauli-Jordan spectrum. In this work we explore different truncation schemes with the criterion that the SSEE so obtained obeys an area law. |
2009.01794 | Sandeep Aashish | Sandeep Aashish | Note on stability and microcausality in Lorentz violating antisymmetric
tensor field | 12 pages | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The fundamental issues of microcausality and energy positivity conditions are
important to be investigated in the context of spontaneous Lorentz violating
theories. We check the microcausality and energy positivity conditions for a
free rank-2 antisymmetric tensor field with spontaneous Lorentz violating term
and a classically equivalent vector theory from dispersion relations and
propagators, and find that the two theories lead to different conditions. While
the antisymmetric tensor theory satisfies energy positivity condition and can
satisfy microcausality condition for a particular choice of vacuum value, the
vector theory violates both energy positivity and microcausality conditions.
| [
{
"created": "Thu, 3 Sep 2020 16:55:18 GMT",
"version": "v1"
}
] | 2020-09-04 | [
[
"Aashish",
"Sandeep",
""
]
] | The fundamental issues of microcausality and energy positivity conditions are important to be investigated in the context of spontaneous Lorentz violating theories. We check the microcausality and energy positivity conditions for a free rank-2 antisymmetric tensor field with spontaneous Lorentz violating term and a classically equivalent vector theory from dispersion relations and propagators, and find that the two theories lead to different conditions. While the antisymmetric tensor theory satisfies energy positivity condition and can satisfy microcausality condition for a particular choice of vacuum value, the vector theory violates both energy positivity and microcausality conditions. |
gr-qc/0401006 | Tetsuya Shiromizu | Tetsuya Shiromizu, Shinya Tomizawa | Spatial infinity in higher dimensional spacetimes | 6 pages, accepted for publication in Physical Review D, published
version | Phys.Rev. D69 (2004) 104012 | 10.1103/PhysRevD.69.104012 | null | gr-qc astro-ph hep-th | null | Motivated by recent studies on the uniqueness or non-uniqueness of higher
dimensional black hole spacetime, we investigate the asymptotic structure of
spatial infinity in n-dimensional spacetimes($n \geq 4$). It turns out that the
geometry of spatial infinity does not have maximal symmetry due to the
non-trivial Weyl tensor {}^{(n-1)}C_{abcd} in general. We also address static
spacetime and its multipole moments P_{a_1 a_2 ... a_s}. Contrasting with four
dimensions, we stress that the local structure of spacetimes cannot be unique
under fixed a multipole moments in static vacuum spacetimes. For example, we
will consider the generalized Schwarzschild spacetimes which are deformed black
hole spacetimes with the same multipole moments as spherical Schwarzschild
black holes. To specify the local structure of static vacuum solution we need
some additional information, at least, the Weyl tensor {}^{(n-2)}C_{abcd} at
spatial infinity.
| [
{
"created": "Sat, 3 Jan 2004 01:52:54 GMT",
"version": "v1"
},
{
"created": "Thu, 8 Jan 2004 05:06:18 GMT",
"version": "v2"
},
{
"created": "Sun, 8 Feb 2004 04:01:01 GMT",
"version": "v3"
},
{
"created": "Wed, 24 Mar 2004 07:56:44 GMT",
"version": "v4"
}
] | 2009-11-10 | [
[
"Shiromizu",
"Tetsuya",
""
],
[
"Tomizawa",
"Shinya",
""
]
] | Motivated by recent studies on the uniqueness or non-uniqueness of higher dimensional black hole spacetime, we investigate the asymptotic structure of spatial infinity in n-dimensional spacetimes($n \geq 4$). It turns out that the geometry of spatial infinity does not have maximal symmetry due to the non-trivial Weyl tensor {}^{(n-1)}C_{abcd} in general. We also address static spacetime and its multipole moments P_{a_1 a_2 ... a_s}. Contrasting with four dimensions, we stress that the local structure of spacetimes cannot be unique under fixed a multipole moments in static vacuum spacetimes. For example, we will consider the generalized Schwarzschild spacetimes which are deformed black hole spacetimes with the same multipole moments as spherical Schwarzschild black holes. To specify the local structure of static vacuum solution we need some additional information, at least, the Weyl tensor {}^{(n-2)}C_{abcd} at spatial infinity. |
gr-qc/9405069 | Dr. Beverly Berger | B.K. Berger, D. Garfinkle, V. Swamy | Detection of Computer Generated Gravitational Waves in Numerical
Cosmologies | 15 pages Plain TeX, 9 pages of figures available on request by FAX or
mail | Gen.Rel.Grav. 27 (1995) 511-527 | 10.1007/BF02105076 | null | gr-qc | null | We propose to study the behavior of complicated numerical solutions to
Einstein's equations for generic cosmologies by following the geodesic motion
of a swarm of test particles. As an example, we consider a cylinder of test
particles initially at rest in the plane symmetric Gowdy universe on $T^3
\times R$. For a circle of test particles in the symmetry plane, the geodesic
equations predict evolution of the circle into distortions and rotations of an
ellipse as well as motion perpendicular to the plane. The evolutionary sequence
of ellipses depends on the initial position of the circle of particles. We
display snapshots of the evolution of the cylinder.
| [
{
"created": "Fri, 27 May 1994 23:50:09 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Berger",
"B. K.",
""
],
[
"Garfinkle",
"D.",
""
],
[
"Swamy",
"V.",
""
]
] | We propose to study the behavior of complicated numerical solutions to Einstein's equations for generic cosmologies by following the geodesic motion of a swarm of test particles. As an example, we consider a cylinder of test particles initially at rest in the plane symmetric Gowdy universe on $T^3 \times R$. For a circle of test particles in the symmetry plane, the geodesic equations predict evolution of the circle into distortions and rotations of an ellipse as well as motion perpendicular to the plane. The evolutionary sequence of ellipses depends on the initial position of the circle of particles. We display snapshots of the evolution of the cylinder. |
2105.05642 | Kimihiro Nomura | Kimihiro Nomura, Daisuke Yoshida | Past extendibility and initial singularity in
Friedmann-Lema\^{i}tre-Robertson-Walker and Bianchi I spacetimes | 33 pages, 3 figures | JCAP07(2021)047 | 10.1088/1475-7516/2021/07/047 | KOBE-COSMO-21-08 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study past-directed extendibility of
Friedmann-Lema\^{i}tre-Robertson-Walker (FLRW) and Bianchi type I spacetimes
with a scale factor vanishing in the past. We give criteria for determining
whether a boundary for past-directed incomplete geodesics is a parallelly
propagated curvature singularity, which cannot necessarily be read off from
scalar curvature invariants. It is clarified that, for incomplete FLRW
spacetime to avoid the singularity, the spacetime necessarily reduces to the
Milne universe or flat de Sitter universe toward the boundary. For incomplete
Bianchi type I spacetime to be free of singularity, it is necessary that the
spacetime asymptotically fits into the product of the extendible isotropic
geometry (Milne or flat de Sitter) and flat space, or, anisotropic spacetime
with specific power law scale factors. Furthermore, we investigate in detail
the time-dependence of the scale factor compatible with the extendibility in
both spacetimes beyond the leading order.
| [
{
"created": "Wed, 12 May 2021 13:21:02 GMT",
"version": "v1"
},
{
"created": "Tue, 27 Jul 2021 03:49:17 GMT",
"version": "v2"
}
] | 2021-07-28 | [
[
"Nomura",
"Kimihiro",
""
],
[
"Yoshida",
"Daisuke",
""
]
] | We study past-directed extendibility of Friedmann-Lema\^{i}tre-Robertson-Walker (FLRW) and Bianchi type I spacetimes with a scale factor vanishing in the past. We give criteria for determining whether a boundary for past-directed incomplete geodesics is a parallelly propagated curvature singularity, which cannot necessarily be read off from scalar curvature invariants. It is clarified that, for incomplete FLRW spacetime to avoid the singularity, the spacetime necessarily reduces to the Milne universe or flat de Sitter universe toward the boundary. For incomplete Bianchi type I spacetime to be free of singularity, it is necessary that the spacetime asymptotically fits into the product of the extendible isotropic geometry (Milne or flat de Sitter) and flat space, or, anisotropic spacetime with specific power law scale factors. Furthermore, we investigate in detail the time-dependence of the scale factor compatible with the extendibility in both spacetimes beyond the leading order. |
2407.16960 | Martin Reiris | Javier Peraza and Martin Reiris | Static vacuum 3+1 black holes that cannot be put into stationary
rotation | 15 pages, 3 figures | null | null | null | gr-qc math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We prove that some of the static Myers/Korotkin-Nicolai (MKN) vacuum 3+1
static black holes cannot be put into stationary rotation. Namely, they cannot
be deformed into axisymmetric stationary vacuum black holes with non-zero
angular momentum. Other than axisymmetry, no assumptions are made on the
possible deformations. The phenomenon occurs in particular for those MKN
solutions for which the distance along the axis between the two horizon's poles
is sufficiently small compared to the square root of its area. The MKN
solutions, sometimes called periodic Schwarzschild, are physically regular but
asymptotically Kasner.
The static rigidity presented here appears to be the first in the literature
of General Relativity.
| [
{
"created": "Wed, 24 Jul 2024 02:57:50 GMT",
"version": "v1"
}
] | 2024-07-25 | [
[
"Peraza",
"Javier",
""
],
[
"Reiris",
"Martin",
""
]
] | We prove that some of the static Myers/Korotkin-Nicolai (MKN) vacuum 3+1 static black holes cannot be put into stationary rotation. Namely, they cannot be deformed into axisymmetric stationary vacuum black holes with non-zero angular momentum. Other than axisymmetry, no assumptions are made on the possible deformations. The phenomenon occurs in particular for those MKN solutions for which the distance along the axis between the two horizon's poles is sufficiently small compared to the square root of its area. The MKN solutions, sometimes called periodic Schwarzschild, are physically regular but asymptotically Kasner. The static rigidity presented here appears to be the first in the literature of General Relativity. |
gr-qc/0612175 | Jia-Chen Hua | Jia-Chen Hua (1, 2), Yong-Chang Huang (2, 3, 4) ((1) Department of
Physics, University of Houston, Houston, USA, (2) Institute of Theoretical
Physics, Beijing University of Technology, Beijing, China, (3) Kavli
Institute for Theoretical Physics, Chinese Academy of Sciences, Beijing,
China, (4) CCAST (World Lab.), Beijing, China) | Quantum Radiation Properties of Dirac Particles in General Nonstationary
Black Holes | This paper has been revised and will appear in Advances in High
Energy Physics. Please refer to the journal reference for the finalized
publication version | Advances in High Energy Physics, vol. 2014, Article ID 707519, 10
pages, 2014 | 10.1155/2014/707519 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Quantum radiation properties of Dirac particles in general nonstationary
black holes in the general case is investigated by both using the method of
generalized tortoise coordinate transformation and considering the asymptotic
behaviors of both the first and second order forms of Dirac equations near the
event horizon. It is generally shown that the temperature and shape of event
horizon of this kind of black holes depend on both the time and different
angles. Further, we give a general expression of the new extra coupling effect
in thermal radiation spectrum of Dirac particles which is missing in that of
scalar particles. Also, we reveal a relationship that is ignored before between
thermal radiation and non-thermal radiation in the case of scalar particles,
which is that the chemical potential in thermal radiation spectrum is equal to
the highest energy of the negative energy state of scalar particles in
non-thermal radiation for general nonstationary black holes.
| [
{
"created": "Thu, 28 Dec 2006 02:50:02 GMT",
"version": "v1"
},
{
"created": "Wed, 18 Apr 2007 22:00:49 GMT",
"version": "v2"
},
{
"created": "Tue, 8 May 2007 09:54:51 GMT",
"version": "v3"
},
{
"created": "Sat, 19 May 2007 03:26:47 GMT",
"version": "v4"
},
{
"created": "Fri, 1 Jun 2007 14:12:45 GMT",
"version": "v5"
},
{
"created": "Tue, 25 Sep 2007 18:25:04 GMT",
"version": "v6"
},
{
"created": "Mon, 11 Nov 2013 10:23:16 GMT",
"version": "v7"
},
{
"created": "Fri, 22 Nov 2013 22:08:17 GMT",
"version": "v8"
}
] | 2014-02-06 | [
[
"Hua",
"Jia-Chen",
""
],
[
"Huang",
"Yong-Chang",
""
]
] | Quantum radiation properties of Dirac particles in general nonstationary black holes in the general case is investigated by both using the method of generalized tortoise coordinate transformation and considering the asymptotic behaviors of both the first and second order forms of Dirac equations near the event horizon. It is generally shown that the temperature and shape of event horizon of this kind of black holes depend on both the time and different angles. Further, we give a general expression of the new extra coupling effect in thermal radiation spectrum of Dirac particles which is missing in that of scalar particles. Also, we reveal a relationship that is ignored before between thermal radiation and non-thermal radiation in the case of scalar particles, which is that the chemical potential in thermal radiation spectrum is equal to the highest energy of the negative energy state of scalar particles in non-thermal radiation for general nonstationary black holes. |
1911.08371 | Shahar Hod | Shahar Hod | No nonminimally coupled massless scalar hair for spherically symmetric
neutral black holes | 8 pages | Physics Letters B 771, 521 (2017) | 10.1016/j.physletb.2017.06.005 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide a remarkably compact proof that spherically symmetric neutral
black holes cannot support static nonminimally coupled massless scalar fields.
The theorem is based on causality restrictions imposed on the energy-momentum
tensor of the fields near the regular black-hole horizon.
| [
{
"created": "Tue, 19 Nov 2019 16:02:58 GMT",
"version": "v1"
}
] | 2019-11-27 | [
[
"Hod",
"Shahar",
""
]
] | We provide a remarkably compact proof that spherically symmetric neutral black holes cannot support static nonminimally coupled massless scalar fields. The theorem is based on causality restrictions imposed on the energy-momentum tensor of the fields near the regular black-hole horizon. |
1902.06783 | Salvatore Capozziello | Gamal G. L. Nashed and Salvatore Capozziello | Charged spherically symmetric black holes in $f(R)$ gravity and their
stability analysis | 17 pages, 5 figures, accepted for publication in Physical Review D.
This version contains an Addendum where a typo is pointed out. arXiv admin
note: text overlap with arXiv:1107.3705 by other authors | Phys. Rev. D 99, 104018 (2019) | 10.1103/PhysRevD.99.104018 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A new class of analytic charged spherically symmetric black hole solutions,
which behave asymptotically as flat or (A)dS spacetimes, is derived for
specific classes of $f(R)$ gravity, i.e., $f(R)=R-2\alpha\sqrt{R}$ and
$f(R)=R-2\alpha\sqrt{R-8\Lambda}$, where $\Lambda$ is the cosmological
constant. These black holes are characterized by the dimensional parameter
$\alpha$ that makes solutions deviate from the standard solutions of general
relativity. The Kretschmann scalar and squared Ricci tensor are shown to depend
on the parameter $\alpha$ which is not allowed to be zero. Thermodynamical
quantities, like entropy, Hawking temperature, quasi-local energy and the Gibbs
free energy are calculated. From these calculations, it is possible to put a
constrain on the dimensional parameter $\alpha$ to have $0<\alpha<0.5$, so that
all thermodynamical quantities have a physical meaning. The interesting result
of these calculations is the possibility of a negative black hole entropy.
Furthermore, present calculations show that for negative energy, particles
inside a black hole, behave as if they have a negative entropy. This fact gives
rise to instability for $f_{RR}<0$. Finally, we study the linear metric
perturbations of the derived black hole solution. We show that for the odd-type
modes, our black hole is always stable and has a radial speed with fixed value
equal to $1$. We also, use the geodesic deviation to derive further stability
conditions.
| [
{
"created": "Mon, 18 Feb 2019 20:11:53 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Apr 2019 06:59:50 GMT",
"version": "v2"
},
{
"created": "Sun, 7 Jul 2019 15:50:42 GMT",
"version": "v3"
},
{
"created": "Sun, 14 Jul 2019 08:48:19 GMT",
"version": "v4"
}
] | 2019-07-18 | [
[
"Nashed",
"Gamal G. L.",
""
],
[
"Capozziello",
"Salvatore",
""
]
] | A new class of analytic charged spherically symmetric black hole solutions, which behave asymptotically as flat or (A)dS spacetimes, is derived for specific classes of $f(R)$ gravity, i.e., $f(R)=R-2\alpha\sqrt{R}$ and $f(R)=R-2\alpha\sqrt{R-8\Lambda}$, where $\Lambda$ is the cosmological constant. These black holes are characterized by the dimensional parameter $\alpha$ that makes solutions deviate from the standard solutions of general relativity. The Kretschmann scalar and squared Ricci tensor are shown to depend on the parameter $\alpha$ which is not allowed to be zero. Thermodynamical quantities, like entropy, Hawking temperature, quasi-local energy and the Gibbs free energy are calculated. From these calculations, it is possible to put a constrain on the dimensional parameter $\alpha$ to have $0<\alpha<0.5$, so that all thermodynamical quantities have a physical meaning. The interesting result of these calculations is the possibility of a negative black hole entropy. Furthermore, present calculations show that for negative energy, particles inside a black hole, behave as if they have a negative entropy. This fact gives rise to instability for $f_{RR}<0$. Finally, we study the linear metric perturbations of the derived black hole solution. We show that for the odd-type modes, our black hole is always stable and has a radial speed with fixed value equal to $1$. We also, use the geodesic deviation to derive further stability conditions. |
1610.04933 | Sandro D. P. Vitenti | Diogo C. F. Celani, Nelson Pinto-Neto, Sandro D. P. Vitenti | Particle Creation in Bouncing Cosmologies | 18 pages, 8 figures | Phys. Rev. D 95, 023523 (2017) | 10.1103/PhysRevD.95.023523 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate scalar particle creation in a set of bouncing models where the
bounce occurs due to quantum cosmological effects described by the
Wheeler-DeWitt equation. The scalar field can be either conformally or
minimally coupled to gravity, and it can be massive or massless, without self
interaction. The analysis is made for models containing a single radiation
fluid, and for the more realistic case of models containing the usual observed
radiation and dust fluids, which can fit most of the observed features of our
Universe, including an almost scale invariant power spectrum of scalar
cosmological perturbations. In the conformal coupling case, the particle
production is negligible. In the minimal coupling case, for massive particles,
the results point to the same physical conclusion within observational
constraints: particle production is most important at the bounce energy scale,
and it is not sensitive neither to its mass nor whether there is dust in the
background model. The only caveat is the case where the particle mass is larger
than the bounce energy scale. On the other hand, the energy density of produced
massive particles depend on their masses and the energy scale of the bounce.
For very large masses and deep bounces, this energy density may overcome that
of the background. In the case of massless particles, the energy density of
produced particles can become comparable to the background energy density only
for bounces occurring at energy scales comparable to the Planck scale or above,
which lies beyond the scope of this paper: we expect that the simple
Wheeler-DeWitt approach we are using should be valid only at scales some few
orders of magnitude below the Planck energy. Nevertheless, in the case in which
dust is present, there is an infrared divergence, which becomes important only
for scales much larger than today's Hubble radius.
| [
{
"created": "Mon, 17 Oct 2016 00:25:51 GMT",
"version": "v1"
}
] | 2017-02-03 | [
[
"Celani",
"Diogo C. F.",
""
],
[
"Pinto-Neto",
"Nelson",
""
],
[
"Vitenti",
"Sandro D. P.",
""
]
] | We investigate scalar particle creation in a set of bouncing models where the bounce occurs due to quantum cosmological effects described by the Wheeler-DeWitt equation. The scalar field can be either conformally or minimally coupled to gravity, and it can be massive or massless, without self interaction. The analysis is made for models containing a single radiation fluid, and for the more realistic case of models containing the usual observed radiation and dust fluids, which can fit most of the observed features of our Universe, including an almost scale invariant power spectrum of scalar cosmological perturbations. In the conformal coupling case, the particle production is negligible. In the minimal coupling case, for massive particles, the results point to the same physical conclusion within observational constraints: particle production is most important at the bounce energy scale, and it is not sensitive neither to its mass nor whether there is dust in the background model. The only caveat is the case where the particle mass is larger than the bounce energy scale. On the other hand, the energy density of produced massive particles depend on their masses and the energy scale of the bounce. For very large masses and deep bounces, this energy density may overcome that of the background. In the case of massless particles, the energy density of produced particles can become comparable to the background energy density only for bounces occurring at energy scales comparable to the Planck scale or above, which lies beyond the scope of this paper: we expect that the simple Wheeler-DeWitt approach we are using should be valid only at scales some few orders of magnitude below the Planck energy. Nevertheless, in the case in which dust is present, there is an infrared divergence, which becomes important only for scales much larger than today's Hubble radius. |
2308.12317 | Saibal Ray | Francisco Tello-Ortiz, \'Angel Rinc\'on, A. Alvarez and Saibal Ray | Gravitationally decoupled Non-Schwarzschild black holes and wormhole
space-times | 15 pages, 6 figures, Accepted in European Physical Journal C (in
press) | null | null | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this article, using gravitational decoupling by means of minimal geometric
deformation approach, we obtain a new spherically symmetric and static black
hole solution. To progress, we close the system by assuming that the average
pressure of the $\theta$-sector is vanishing. Also, we tackle the problem
regarding how, for a given minimally deformed black hole solution, one can
connect it to a wormhole space-time.
| [
{
"created": "Wed, 23 Aug 2023 10:28:30 GMT",
"version": "v1"
}
] | 2023-08-25 | [
[
"Tello-Ortiz",
"Francisco",
""
],
[
"Rincón",
"Ángel",
""
],
[
"Alvarez",
"A.",
""
],
[
"Ray",
"Saibal",
""
]
] | In this article, using gravitational decoupling by means of minimal geometric deformation approach, we obtain a new spherically symmetric and static black hole solution. To progress, we close the system by assuming that the average pressure of the $\theta$-sector is vanishing. Also, we tackle the problem regarding how, for a given minimally deformed black hole solution, one can connect it to a wormhole space-time. |
gr-qc/9805066 | T. P. Singh | T. P. Singh | Gravitational Collapse, Black Holes and Naked Singularities | 17 pages, Latex File. Based on a talk given at the Discussion
Workshop on Black Holes, Bangalore, 9-12 Dec. 1997, to appear in the
Conference Proceedings | J.Astrophys.Astron.20:221,1999 | 10.1007/BF02702354 | TIFR Preprint | gr-qc astro-ph hep-th | null | This article gives an elementary review of gravitational collapse and the
cosmic censorship hypothesis. Known models of collapse resulting in the
formation of black holes and naked singularities are summarized. These models,
when taken together, suggest that the censorship hypothesis may not hold in
classical general relativity. The nature of the quantum processes that take
place near a naked singularity, and their possible implication for
observations, is briefly discussed.
| [
{
"created": "Mon, 18 May 1998 13:04:53 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Singh",
"T. P.",
""
]
] | This article gives an elementary review of gravitational collapse and the cosmic censorship hypothesis. Known models of collapse resulting in the formation of black holes and naked singularities are summarized. These models, when taken together, suggest that the censorship hypothesis may not hold in classical general relativity. The nature of the quantum processes that take place near a naked singularity, and their possible implication for observations, is briefly discussed. |
2009.10204 | Vladimir Ivashchuk | V. D. Ivashchuk and A. A. Kobtsev | On stable exponential cosmological solutions with two factor spaces in
$(1+ m + 2)$-dimensional EGB model with $\Lambda$-term | 24 pages, 3 figures, Latex, a section (on D=4) with corresponding
references is omitted and 3 figures are replaced | null | null | IGC-RUDN-2020-11/2 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A $(m+ 3)$-dimensional Einstein-Gauss-Bonnet gravitational model including
the Gauss-Bonnet term and the cosmological term $\Lambda$ is considered. Exact
solutions with exponential time dependence of two scale factors, governed by
two Hubble-like parameters $H >0$ and $h \neq H$, corresponding to factor
spaces of dimensions $m >2$ and $l = 2$, respectively, are found. Under certain
restrictions on $x = h/H $, the stability of the solutions in a class of
cosmological solutions with diagonal metrics is proved. A subclass of solutions
with small enough variation of the effective gravitational constant $G$ is
considered and the stability of all solutions from this subclass is shown.
| [
{
"created": "Mon, 21 Sep 2020 22:27:13 GMT",
"version": "v1"
},
{
"created": "Thu, 12 Nov 2020 22:41:02 GMT",
"version": "v2"
}
] | 2020-11-16 | [
[
"Ivashchuk",
"V. D.",
""
],
[
"Kobtsev",
"A. A.",
""
]
] | A $(m+ 3)$-dimensional Einstein-Gauss-Bonnet gravitational model including the Gauss-Bonnet term and the cosmological term $\Lambda$ is considered. Exact solutions with exponential time dependence of two scale factors, governed by two Hubble-like parameters $H >0$ and $h \neq H$, corresponding to factor spaces of dimensions $m >2$ and $l = 2$, respectively, are found. Under certain restrictions on $x = h/H $, the stability of the solutions in a class of cosmological solutions with diagonal metrics is proved. A subclass of solutions with small enough variation of the effective gravitational constant $G$ is considered and the stability of all solutions from this subclass is shown. |
gr-qc/0311093 | Plamen Fiziev | T.L. Boyadjiev, P.P. Fiziev | Numerical Modeling of Charged Black Holes with Massive Dilaton | talk given at V International Congress on Mathematical Modeling, Sep.
30 -- Oct. 6, Dubna, Russia, 2002: http://www.jinr.ru/vicmm/ latex file, 17
pages, 14 figures | null | null | P11-2002-1 | gr-qc | null | In this paper the static, spherically symmetric and electrically charged
black hole solutions in Einstein-Born-Infeld gravity with massive dilaton are
investigated numerically.
The Continuous Analog of Newton Method (CANM) is used to solve the
corresponding nonlinear multipoint boundary value problems (BVPs). The
linearized BVPs are solved numerically by means of collocation scheme of fourth
order.
A special class of solutions are the extremal ones. We show that the extremal
horizons within the framework of the model satisfy some nonlinear system of
algebraic equations. Depending on the charge $q$ and dilaton mass $\gamma$, the
black holes can have no more than three horizons. This allows us to construct
some Hermite polynomial of third order. Its real roots describe the number, the
type and other characteristics of the horizons.
| [
{
"created": "Fri, 28 Nov 2003 17:16:42 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Boyadjiev",
"T. L.",
""
],
[
"Fiziev",
"P. P.",
""
]
] | In this paper the static, spherically symmetric and electrically charged black hole solutions in Einstein-Born-Infeld gravity with massive dilaton are investigated numerically. The Continuous Analog of Newton Method (CANM) is used to solve the corresponding nonlinear multipoint boundary value problems (BVPs). The linearized BVPs are solved numerically by means of collocation scheme of fourth order. A special class of solutions are the extremal ones. We show that the extremal horizons within the framework of the model satisfy some nonlinear system of algebraic equations. Depending on the charge $q$ and dilaton mass $\gamma$, the black holes can have no more than three horizons. This allows us to construct some Hermite polynomial of third order. Its real roots describe the number, the type and other characteristics of the horizons. |
2211.07278 | Isobel Romero-Shaw | Isobel M. Romero-Shaw, Nicholas Loutrel, Michael Zevin | Inferring Interference: Identifying a Perturbing Tertiary with Eccentric
Gravitational Wave Burst Timing | Version accepted for publication in PRD | null | 10.1103/PhysRevD.107.122001 | null | gr-qc astro-ph.HE astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | [Abridged] Binary black holes may form and merge dynamically. These binaries
are likely to become bound with high eccentricities, resulting in a burst of
gravitational radiation at their point of closest approach. When such a binary
is perturbed by a third body, the evolution of the orbit is affected, and
gravitational-wave burst times are altered. The bursts times therefore encode
information about the tertiary. In order to extract this information, we
require a prescription for the relationship between the tertiary properties and
the gravitational-wave burst times. In this paper, we demonstrate a toy model
for the burst times of a secular three-body system. We show how Bayesian
inference can be employed to deduce the tertiary properties when the bursts are
detected by next-generation ground-based gravitational-wave detectors. We study
the bursts from an eccentric binary with a total mass of $60$~M$_\odot$
orbiting an $6 \times 10^{8}$~M$_\odot$ supermassive black hole. When we assume
no knowledge of the eccentric binary, we are unable to tightly constrain the
existence or properties of the tertiary, and we recover biased posterior
probability distributions for the parameters of the eccentric binary. However,
when the properties of the binary are already well-known -- as is likely if the
late inspiral and merger are also detected -- we are able to more accurately
infer the mass of the perturber, $m_3$, and its distance from the binary, $R$.
When we assume measurement precision on the binary parameters consistent with
expectations for next-generation gravitational-wave detectors, we can be
greater than $90\%$ confident that the binary is perturbed. [...]
| [
{
"created": "Mon, 14 Nov 2022 11:19:38 GMT",
"version": "v1"
},
{
"created": "Sun, 20 Nov 2022 21:26:41 GMT",
"version": "v2"
},
{
"created": "Tue, 23 May 2023 09:51:31 GMT",
"version": "v3"
}
] | 2023-06-21 | [
[
"Romero-Shaw",
"Isobel M.",
""
],
[
"Loutrel",
"Nicholas",
""
],
[
"Zevin",
"Michael",
""
]
] | [Abridged] Binary black holes may form and merge dynamically. These binaries are likely to become bound with high eccentricities, resulting in a burst of gravitational radiation at their point of closest approach. When such a binary is perturbed by a third body, the evolution of the orbit is affected, and gravitational-wave burst times are altered. The bursts times therefore encode information about the tertiary. In order to extract this information, we require a prescription for the relationship between the tertiary properties and the gravitational-wave burst times. In this paper, we demonstrate a toy model for the burst times of a secular three-body system. We show how Bayesian inference can be employed to deduce the tertiary properties when the bursts are detected by next-generation ground-based gravitational-wave detectors. We study the bursts from an eccentric binary with a total mass of $60$~M$_\odot$ orbiting an $6 \times 10^{8}$~M$_\odot$ supermassive black hole. When we assume no knowledge of the eccentric binary, we are unable to tightly constrain the existence or properties of the tertiary, and we recover biased posterior probability distributions for the parameters of the eccentric binary. However, when the properties of the binary are already well-known -- as is likely if the late inspiral and merger are also detected -- we are able to more accurately infer the mass of the perturber, $m_3$, and its distance from the binary, $R$. When we assume measurement precision on the binary parameters consistent with expectations for next-generation gravitational-wave detectors, we can be greater than $90\%$ confident that the binary is perturbed. [...] |
1707.05757 | Bishop Mongwane | Bishop Mongwane | Characteristic Formulation for Metric $f(R)$ Gravity | 20 pages | Phys. Rev. D 96, 024028 (2017) | 10.1103/PhysRevD.96.024028 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In recent years, the Characteristic formulation of numerical relativity has
found increasing use in the extraction of gravitational radiation from
numerically generated spacetimes. In this paper, we formulate the
Characteristic initial value problem for $f(R)$ gravity. We consider, in
particular, the vacuum field equations of Metric $f(R)$ gravity in the Jordan
frame, without utilising the dynamical equivalence with scalar-tensor theories.
We present the full hierarchy of non-linear hypersurface and evolution
equations necessary for numerical implementation in both tensorial and eth
forms. Furthermore, we specialise the resulting equations to situations where
the spacetime is almost Minkowski and almost Schwarszchild using standard
linearization techniques. We obtain analytic solutions for the dominant
$\ell=2$ mode and show that they satisfy the concomitant constraints. These
results are ideally suited as testbed solutions for numerical codes. Finally,
we point out that the Characteristic formulation can be used as a complementary
analytic tool to the $1+1+2$ semi-tetrad formulation.
| [
{
"created": "Tue, 18 Jul 2017 17:34:42 GMT",
"version": "v1"
}
] | 2017-07-19 | [
[
"Mongwane",
"Bishop",
""
]
] | In recent years, the Characteristic formulation of numerical relativity has found increasing use in the extraction of gravitational radiation from numerically generated spacetimes. In this paper, we formulate the Characteristic initial value problem for $f(R)$ gravity. We consider, in particular, the vacuum field equations of Metric $f(R)$ gravity in the Jordan frame, without utilising the dynamical equivalence with scalar-tensor theories. We present the full hierarchy of non-linear hypersurface and evolution equations necessary for numerical implementation in both tensorial and eth forms. Furthermore, we specialise the resulting equations to situations where the spacetime is almost Minkowski and almost Schwarszchild using standard linearization techniques. We obtain analytic solutions for the dominant $\ell=2$ mode and show that they satisfy the concomitant constraints. These results are ideally suited as testbed solutions for numerical codes. Finally, we point out that the Characteristic formulation can be used as a complementary analytic tool to the $1+1+2$ semi-tetrad formulation. |
gr-qc/0206053 | Martin Bojowald | Martin Bojowald | Quantization Ambiguities in Isotropic Quantum Geometry | 20 pages, 6 figures | Class.Quant.Grav.19:5113-5230,2002 | 10.1088/0264-9381/19/20/306 | CGPG-02/6-1 | gr-qc quant-ph | null | Some typical quantization ambiguities of quantum geometry are studied within
isotropic models. Since this allows explicit computations of operators and
their spectra, one can investigate the effects of ambiguities in a quantitative
manner. It is shown that those ambiguities do not affect the fate of the
classical singularity, demonstrating that the absence of a singularity in loop
quantum cosmology is a robust implication of the general quantization scheme.
The calculations also allow conclusions about modified operators in the full
theory. In particular, using holonomies in a non-fundamental representation of
SU(2) to quantize connection components turns out to lead to significant
corrections to classical behavior at macroscopic volume for large values of the
spin of the chosen representation.
| [
{
"created": "Tue, 18 Jun 2002 14:27:47 GMT",
"version": "v1"
}
] | 2011-09-30 | [
[
"Bojowald",
"Martin",
""
]
] | Some typical quantization ambiguities of quantum geometry are studied within isotropic models. Since this allows explicit computations of operators and their spectra, one can investigate the effects of ambiguities in a quantitative manner. It is shown that those ambiguities do not affect the fate of the classical singularity, demonstrating that the absence of a singularity in loop quantum cosmology is a robust implication of the general quantization scheme. The calculations also allow conclusions about modified operators in the full theory. In particular, using holonomies in a non-fundamental representation of SU(2) to quantize connection components turns out to lead to significant corrections to classical behavior at macroscopic volume for large values of the spin of the chosen representation. |
2305.03744 | Marco Astorino | Marco Astorino and Giovanni Boldi | Plebanski-Demianski goes NUTs (to remove the Misner string) | v7: 30 pages, 2 figures, published version | JHEP 08 (2023) 085 | 10.1007/JHEP08(2023)085 | IFUM-1105-FT, LIFT-3-1.23 | gr-qc hep-th | http://creativecommons.org/licenses/by-nc-sa/4.0/ | We present a general procedure, based on the Ehlers transformation of the
Ernst equations, to add the gravitomagnetic mass to the whole
Plebanski-Demianski family of solutions. We can efficiently generate a large
class of accelerating black holes, such as Reissner-Nordstrom or Kerr-Newman,
endowed with the NUT parameter. The full rotating version carries a couple of
independent NUT charges, one associated to the black hole and the other to the
accelerating Rindler background. The two NUT parameters can be coupled to
remove the axial irregularity which causes the Misner string, still remaining
with a Lorentzian spacetime, without the need to impose periodic time. All the
metrics we build are not of D-type according to the Petrov classification, but
type-I, so they belong to a more general category with respect to C-metrics and
the Plebanski-Demianski seed. A convenient form of the most general type D
black hole solution in general relativity, coupled with Maxwell
electromagnetism, is obtained when switching off one of the two NUT parameters.
| [
{
"created": "Fri, 5 May 2023 18:00:00 GMT",
"version": "v1"
},
{
"created": "Mon, 15 May 2023 17:54:47 GMT",
"version": "v2"
},
{
"created": "Sat, 3 Jun 2023 02:32:32 GMT",
"version": "v3"
},
{
"created": "Fri, 16 Jun 2023 17:58:06 GMT",
"version": "v4"
},
{
"created": "Mon, 3 Jul 2023 16:30:52 GMT",
"version": "v5"
},
{
"created": "Thu, 13 Jul 2023 17:05:07 GMT",
"version": "v6"
},
{
"created": "Sun, 20 Aug 2023 10:23:34 GMT",
"version": "v7"
}
] | 2023-08-22 | [
[
"Astorino",
"Marco",
""
],
[
"Boldi",
"Giovanni",
""
]
] | We present a general procedure, based on the Ehlers transformation of the Ernst equations, to add the gravitomagnetic mass to the whole Plebanski-Demianski family of solutions. We can efficiently generate a large class of accelerating black holes, such as Reissner-Nordstrom or Kerr-Newman, endowed with the NUT parameter. The full rotating version carries a couple of independent NUT charges, one associated to the black hole and the other to the accelerating Rindler background. The two NUT parameters can be coupled to remove the axial irregularity which causes the Misner string, still remaining with a Lorentzian spacetime, without the need to impose periodic time. All the metrics we build are not of D-type according to the Petrov classification, but type-I, so they belong to a more general category with respect to C-metrics and the Plebanski-Demianski seed. A convenient form of the most general type D black hole solution in general relativity, coupled with Maxwell electromagnetism, is obtained when switching off one of the two NUT parameters. |
gr-qc/0001050 | Madhavan Varadarajan | Madhavan Varadarajan (RRI, India) | Fock representations from U(1) holonomy algebras | Latex file, 30 pages, to appear in Phys Rev D | Phys.Rev. D61 (2000) 104001 | 10.1103/PhysRevD.61.104001 | null | gr-qc | null | We revisit the quantization of U(1) holonomy algebras using the abelian C*
algebra based techniques which form the mathematical underpinnings of current
efforts to construct loop quantum gravity. In particular, we clarify the role
of ``smeared loops'' and of Poincare invariance in the construction of Fock
representations of these algebras. This enables us to critically re-examine
early pioneering efforts to construct Fock space representations of linearised
gravity and free Maxwell theory from holonomy algebras through an application
of the (then current) techniques of loop quantum gravity.
| [
{
"created": "Wed, 19 Jan 2000 09:02:52 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Varadarajan",
"Madhavan",
"",
"RRI, India"
]
] | We revisit the quantization of U(1) holonomy algebras using the abelian C* algebra based techniques which form the mathematical underpinnings of current efforts to construct loop quantum gravity. In particular, we clarify the role of ``smeared loops'' and of Poincare invariance in the construction of Fock representations of these algebras. This enables us to critically re-examine early pioneering efforts to construct Fock space representations of linearised gravity and free Maxwell theory from holonomy algebras through an application of the (then current) techniques of loop quantum gravity. |
1001.5314 | Muhammad Sharif | M. Sharif and G. Abbas | Effects of the Electromagnetic Field on Five-dimensional Gravitational
Collapse | 15 pages, accepted for publication in J. Korean Physical Society | J. Korean Physical Society 56(2010)529-535 | 10.3938/jkps.56.529 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper investigates the five-dimensional(5D) spherically symmetric
gravitational collapse with positive cosmological constant in the presence of
an electromagnetic field. The junction conditions between the 5D non-static
interior and the static exterior spacetimes are derived using the Israel
criteria modified by Santos. We use the energy conditions to discuss solution
to the field equations of the interior spacetime with a charged perfect fluid
for the marginally bound and the non-marginally bound cases. We found that the
range of apparent horizon was larger than that for 4D gravitational collapse
with an electromagnetic field. This analysis gives the irreducible and the
reducible extensions of 4D perfect fluid collapse with an electromagnetic field
and 5D perfect fluid collapse, respectively. Moreover, for the later case, the
results can be recovered under some restrictions.
| [
{
"created": "Fri, 29 Jan 2010 02:40:22 GMT",
"version": "v1"
}
] | 2015-05-18 | [
[
"Sharif",
"M.",
""
],
[
"Abbas",
"G.",
""
]
] | This paper investigates the five-dimensional(5D) spherically symmetric gravitational collapse with positive cosmological constant in the presence of an electromagnetic field. The junction conditions between the 5D non-static interior and the static exterior spacetimes are derived using the Israel criteria modified by Santos. We use the energy conditions to discuss solution to the field equations of the interior spacetime with a charged perfect fluid for the marginally bound and the non-marginally bound cases. We found that the range of apparent horizon was larger than that for 4D gravitational collapse with an electromagnetic field. This analysis gives the irreducible and the reducible extensions of 4D perfect fluid collapse with an electromagnetic field and 5D perfect fluid collapse, respectively. Moreover, for the later case, the results can be recovered under some restrictions. |
1904.00907 | D\'aniel Barta | D\'aniel Barta | Effect of viscosity and thermal conductivity on the radial oscillation
and relaxation of relativistic stars | null | Class. Quantum Grav. 36 (2019) 215012 | 10.1088/1361-6382/ab472e | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we present a generic formulation of the linearized dynamical
equations governing small adiabatic radial oscillations of relativistic stars.
The dynamical equations are derived by taking into consideration those effects
of viscosity and thermal conductivity of neutron-star matter which directly
determine the minimum period of observable pulsars. A variational principle is
applied to determine a discrete set of eigenfunctions with complex eigenvalues.
The real and imaginary parts of eigenvalues represent the squared natural
frequencies and relaxation time of radial oscillations of non-rotating neutron
stars, respectively. We provide a suitable framework which may be supplemented
with various potential species of cold-nuclear-matter models to compute the
spectra of the normalized eigenfrequencies with a certain numerical precision.
In the last section, we provide a qualitative estimation of the rate at which
viscosity and thermal conductivity drain the kinetic energy of radial
oscillation mode in reasonably uniform neutron stars, without relying on
explicit numerical computations.
| [
{
"created": "Mon, 1 Apr 2019 15:20:21 GMT",
"version": "v1"
},
{
"created": "Sat, 14 Sep 2019 16:13:47 GMT",
"version": "v2"
}
] | 2022-05-11 | [
[
"Barta",
"Dániel",
""
]
] | In this paper we present a generic formulation of the linearized dynamical equations governing small adiabatic radial oscillations of relativistic stars. The dynamical equations are derived by taking into consideration those effects of viscosity and thermal conductivity of neutron-star matter which directly determine the minimum period of observable pulsars. A variational principle is applied to determine a discrete set of eigenfunctions with complex eigenvalues. The real and imaginary parts of eigenvalues represent the squared natural frequencies and relaxation time of radial oscillations of non-rotating neutron stars, respectively. We provide a suitable framework which may be supplemented with various potential species of cold-nuclear-matter models to compute the spectra of the normalized eigenfrequencies with a certain numerical precision. In the last section, we provide a qualitative estimation of the rate at which viscosity and thermal conductivity drain the kinetic energy of radial oscillation mode in reasonably uniform neutron stars, without relying on explicit numerical computations. |
1401.3044 | Arthur Suvorov | Arthur Suvorov and Anthony W.C. Lun | Closed Form Solutions To Bosonic Perturbations In General Relativity | 15 pages, 0 figures | null | null | null | gr-qc astro-ph.HE math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present some results regarding metric perturbations in general relativity
and other metric theories of gravity. In particular, using the Newman Penrose
variables, we write down and discuss the equations which govern tensor field
perturbations of ranks $0, \pm 1$ and $\pm 2$ (scalar,vector,tensor bosonic
perturbations) over certain space-times that admit specific background metrics
expressible in isotropic coordinates. Armed with these equations, we are able
to develop the Hadamard series which can be associated with the fundamental
solution of the equations, wherein we introduce an inhomogeneous singularity at
the physical space-time point of the perturbing particle. The Hadamard series
is then used to generate closed form solutions by making choices for an
appropriate ansatz solution. In particular, we solve for the spin-weighted
electrostatic potential for the Reissner-Nordstrom black hole and for the fully
dynamical potential for the Friedmann-Robertson-Walker cosmological solution.
| [
{
"created": "Tue, 14 Jan 2014 01:23:37 GMT",
"version": "v1"
}
] | 2014-01-15 | [
[
"Suvorov",
"Arthur",
""
],
[
"Lun",
"Anthony W. C.",
""
]
] | We present some results regarding metric perturbations in general relativity and other metric theories of gravity. In particular, using the Newman Penrose variables, we write down and discuss the equations which govern tensor field perturbations of ranks $0, \pm 1$ and $\pm 2$ (scalar,vector,tensor bosonic perturbations) over certain space-times that admit specific background metrics expressible in isotropic coordinates. Armed with these equations, we are able to develop the Hadamard series which can be associated with the fundamental solution of the equations, wherein we introduce an inhomogeneous singularity at the physical space-time point of the perturbing particle. The Hadamard series is then used to generate closed form solutions by making choices for an appropriate ansatz solution. In particular, we solve for the spin-weighted electrostatic potential for the Reissner-Nordstrom black hole and for the fully dynamical potential for the Friedmann-Robertson-Walker cosmological solution. |
gr-qc/0305012 | Akihiro Ishibashi | Akihiro Ishibashi and Robert M. Wald | Dynamics in Non-Globally-Hyperbolic Static Spacetimes II: General
Analysis of Prescriptions for Dynamics | Latex, 17 pages, no figures | Class.Quant.Grav. 20 (2003) 3815-3826 | 10.1088/0264-9381/20/16/318 | null | gr-qc hep-th | null | It was previously shown by one of us that in any static,
non-globally-hyperbolic, spacetime it is always possible to define a sensible
dynamics for a Klein-Gordon scalar field. The prescription proposed for doing
so involved viewing the spatial derivative part, $A$, of the wave operator as
an operator on a certain $L^2$ Hilbert space $\mathcal H$ and then defining a
positive, self-adjoint operator on $\mathcal H$ by taking the Friedrichs
extension (or other positive extension) of $A$. However, this analysis left
open the possibility that there could be other inequivalent prescriptions of a
completely different nature that might also yield satisfactory definitions of
the dynamics of a scalar field. We show here that this is not the case.
Specifically, we show that if the dynamics agrees locally with the dynamics
defined by the wave equation, if it admits a suitable conserved energy, and if
it satisfies certain other specified conditions, then it must correspond to the
dynamics defined by choosing some positive, self-adjoint extension of $A$ on
$\mathcal H$. Thus, subject to our requirements, the previously given
prescription is the only possible way of defining the dynamics of a scalar
field in a static, non-globally-hyperbolic, spacetime. In a subsequent paper,
this result will be applied to the analysis of scalar, electromagnetic, and
gravitational perturbations of anti-de Sitter spacetime. By doing so, we will
determine all possible choices of boundary conditions at infinity in anti-de
Sitter spacetime that give rise to sensible dynamics.
| [
{
"created": "Fri, 2 May 2003 20:03:40 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Ishibashi",
"Akihiro",
""
],
[
"Wald",
"Robert M.",
""
]
] | It was previously shown by one of us that in any static, non-globally-hyperbolic, spacetime it is always possible to define a sensible dynamics for a Klein-Gordon scalar field. The prescription proposed for doing so involved viewing the spatial derivative part, $A$, of the wave operator as an operator on a certain $L^2$ Hilbert space $\mathcal H$ and then defining a positive, self-adjoint operator on $\mathcal H$ by taking the Friedrichs extension (or other positive extension) of $A$. However, this analysis left open the possibility that there could be other inequivalent prescriptions of a completely different nature that might also yield satisfactory definitions of the dynamics of a scalar field. We show here that this is not the case. Specifically, we show that if the dynamics agrees locally with the dynamics defined by the wave equation, if it admits a suitable conserved energy, and if it satisfies certain other specified conditions, then it must correspond to the dynamics defined by choosing some positive, self-adjoint extension of $A$ on $\mathcal H$. Thus, subject to our requirements, the previously given prescription is the only possible way of defining the dynamics of a scalar field in a static, non-globally-hyperbolic, spacetime. In a subsequent paper, this result will be applied to the analysis of scalar, electromagnetic, and gravitational perturbations of anti-de Sitter spacetime. By doing so, we will determine all possible choices of boundary conditions at infinity in anti-de Sitter spacetime that give rise to sensible dynamics. |
1702.06030 | Maurizio Gasperini | M. Gasperini | Constraints on the production of primordial magnetic seeds in pre-big
bang cosmology | 20 pages, 3 figures. The discussion of the process of seed production
is limited to the case of growing electromagnetic coupling. A new figure
added, typos corrected. To appear in JCAP (2017) | JCAP 06 (2017) 017 | 10.1088/1475-7516/2017/06/017 | BA-TH/710-17 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the amplification of the electromagnetic fluctuations, and the
production of "seeds" for the cosmic magnetic fields, in a class of string
cosmology models whose scalar and tensor perturbations reproduce current
observations and satisfy known phenomenological constraints. We find that the
condition of efficient seeds production can be satisfied and compatible with
all constraints only in a restricted region of parameter space, but we show
that such a region has significant intersections with the portions of parameter
space where the produced background of relic gravitational waves is strong
enough to be detectable by aLIGO/Virgo and/or by eLISA.
| [
{
"created": "Mon, 20 Feb 2017 15:55:58 GMT",
"version": "v1"
},
{
"created": "Sun, 9 Apr 2017 22:00:52 GMT",
"version": "v2"
},
{
"created": "Mon, 5 Jun 2017 13:21:44 GMT",
"version": "v3"
}
] | 2017-06-14 | [
[
"Gasperini",
"M.",
""
]
] | We study the amplification of the electromagnetic fluctuations, and the production of "seeds" for the cosmic magnetic fields, in a class of string cosmology models whose scalar and tensor perturbations reproduce current observations and satisfy known phenomenological constraints. We find that the condition of efficient seeds production can be satisfied and compatible with all constraints only in a restricted region of parameter space, but we show that such a region has significant intersections with the portions of parameter space where the produced background of relic gravitational waves is strong enough to be detectable by aLIGO/Virgo and/or by eLISA. |
gr-qc/9602029 | Franz Schunck | Eckehard W. Mielke and Franz E. Schunck | Reconstructing the inflaton potential for an almost flat COBE spectrum | 20 pages REVTeX, uuencoded with 7 postscript figures, uses psfig | Phys.Rev. D52 (1995) 672-678 | 10.1103/PhysRevD.52.672 | null | gr-qc astro-ph hep-ph | null | Using the Hubble parameter as new `inverse time' coordinate ($H$-formalism),
a new method of reconstructing the inflaton potential is developed also using
older results which, in principle, is applicable to any order of the slow-roll
approximation. In first and second order, we need three observational data as
inputs: the scalar spectral index $n_s$ and the amplitudes of the scalar and
the tensor spectrum. We find constraints between the values of $n_s$ and the
corresponding values for the wavelength $\lambda $. By imposing a dependence
$\lambda (n_s)$, we were able to reconstruct and visualize inflationary
potentials which are compatible with recent COBE and other astrophysical
observations. >From the reconstructed potentials, it becomes clear that one
cannot find only one special value of the scalar spectral index $n_s$.
| [
{
"created": "Tue, 13 Feb 1996 20:36:24 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Mielke",
"Eckehard W.",
""
],
[
"Schunck",
"Franz E.",
""
]
] | Using the Hubble parameter as new `inverse time' coordinate ($H$-formalism), a new method of reconstructing the inflaton potential is developed also using older results which, in principle, is applicable to any order of the slow-roll approximation. In first and second order, we need three observational data as inputs: the scalar spectral index $n_s$ and the amplitudes of the scalar and the tensor spectrum. We find constraints between the values of $n_s$ and the corresponding values for the wavelength $\lambda $. By imposing a dependence $\lambda (n_s)$, we were able to reconstruct and visualize inflationary potentials which are compatible with recent COBE and other astrophysical observations. >From the reconstructed potentials, it becomes clear that one cannot find only one special value of the scalar spectral index $n_s$. |
1112.1637 | Valeriu Predoi | V. Predoi (for the LIGO Scientific Collaboration, and for the Virgo
Collaboration), and K. Hurley (for IPN) | Search for gravitational waves associated with the InterPlanetary
Network short gamma ray bursts | Methods paper; Proceedings for Eduardo Amaldi 9 Conference on
Gravitational Waves, July 2011, Cardiff, UK | null | 10.1088/1742-6596/363/1/012034 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We outline the scientific motivation behind a search for gravitational waves
associated with short gamma ray bursts detected by the InterPlanetary Network
(IPN) during LIGO's fifth science run and Virgo's first science run. The IPN
localisation of short gamma ray bursts is limited to extended error boxes of
different shapes and sizes and a search on these error boxes poses a series of
challenges for data analysis. We will discuss these challenges and outline the
methods to optimise the search over these error boxes.
| [
{
"created": "Wed, 7 Dec 2011 17:26:19 GMT",
"version": "v1"
}
] | 2019-08-15 | [
[
"Predoi",
"V.",
"",
"for the LIGO Scientific Collaboration, and for the Virgo\n Collaboration"
],
[
"Hurley",
"K.",
"",
"for IPN"
]
] | We outline the scientific motivation behind a search for gravitational waves associated with short gamma ray bursts detected by the InterPlanetary Network (IPN) during LIGO's fifth science run and Virgo's first science run. The IPN localisation of short gamma ray bursts is limited to extended error boxes of different shapes and sizes and a search on these error boxes poses a series of challenges for data analysis. We will discuss these challenges and outline the methods to optimise the search over these error boxes. |
gr-qc/0311069 | Neil J. Cornish | Louis J. Rubbo, Neil J. Cornish & Olivier Poujade | Forward Modeling of Space-borne Gravitational Wave Detectors | 14 Pages, 14 Figures, RevTex 4 | Phys.Rev. D69 (2004) 082003 | 10.1103/PhysRevD.69.082003 | null | gr-qc | null | Planning is underway for several space-borne gravitational wave observatories
to be built in the next ten to twenty years. Realistic and efficient forward
modeling will play a key role in the design and operation of these
observatories. Space-borne interferometric gravitational wave detectors operate
very differently from their ground based counterparts. Complex orbital motion,
virtual interferometry, and finite size effects complicate the description of
space-based systems, while nonlinear control systems complicate the description
of ground based systems. Here we explore the forward modeling of space-based
gravitational wave detectors and introduce an adiabatic approximation to the
detector response that significantly extends the range of the standard low
frequency approximation. The adiabatic approximation will aid in the
development of data analysis techniques, and improve the modeling of
astrophysical parameter extraction.
| [
{
"created": "Fri, 21 Nov 2003 01:14:33 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Rubbo",
"Louis J.",
""
],
[
"Cornish",
"Neil J.",
""
],
[
"Poujade",
"Olivier",
""
]
] | Planning is underway for several space-borne gravitational wave observatories to be built in the next ten to twenty years. Realistic and efficient forward modeling will play a key role in the design and operation of these observatories. Space-borne interferometric gravitational wave detectors operate very differently from their ground based counterparts. Complex orbital motion, virtual interferometry, and finite size effects complicate the description of space-based systems, while nonlinear control systems complicate the description of ground based systems. Here we explore the forward modeling of space-based gravitational wave detectors and introduce an adiabatic approximation to the detector response that significantly extends the range of the standard low frequency approximation. The adiabatic approximation will aid in the development of data analysis techniques, and improve the modeling of astrophysical parameter extraction. |
2005.05982 | Jorge Delgado B.S. | Jorge F. M. Delgado, Carlos A. R. Herdeiro, Eugen Radu | Rotating Axion Boson Stars | v2: minor improvements and added references. Matches version to
appear in JCAP | null | 10.1088/1475-7516/2020/06/037 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct and study rotating axion boson stars (RABSs). These are the
spinning generalisations of the spherical gravitating solitons recently
introduced in arXiv:1909.05515. RABSs are asymptotically flat, stationary,
axially symmetric, everywhere regular solutions of the Einstein-Klein-Gordon
theory, in the presence of a periodic scalar potential arising in models of
axion-like particles. The potential is characterised by two parameters: the
mass of the scalar field $m_a$ and the decay constant $f_a$. We present an
overview of the solution space, for different values of $f_a$, and analyse some
of their phenomenological properties. For large decay constants the solutions
become identical to the standard spinning mini boson stars. For small decay
constants, on the other hand, the solutions develop distinctive features. In
particular, we analyse their compactness, the emergence of ergoregions, light
rings and the distribution of stable and unstable equatorial timelike circular
orbits, including the innermost stable circular orbit. We also establish the
occurrence of violations of the strong energy condition for physical observers,
for some RABSs. We observe some analogy between RABSs and spinning gravitating
$Q$-balls.
| [
{
"created": "Tue, 12 May 2020 18:00:04 GMT",
"version": "v1"
},
{
"created": "Wed, 27 May 2020 09:47:07 GMT",
"version": "v2"
}
] | 2020-07-01 | [
[
"Delgado",
"Jorge F. M.",
""
],
[
"Herdeiro",
"Carlos A. R.",
""
],
[
"Radu",
"Eugen",
""
]
] | We construct and study rotating axion boson stars (RABSs). These are the spinning generalisations of the spherical gravitating solitons recently introduced in arXiv:1909.05515. RABSs are asymptotically flat, stationary, axially symmetric, everywhere regular solutions of the Einstein-Klein-Gordon theory, in the presence of a periodic scalar potential arising in models of axion-like particles. The potential is characterised by two parameters: the mass of the scalar field $m_a$ and the decay constant $f_a$. We present an overview of the solution space, for different values of $f_a$, and analyse some of their phenomenological properties. For large decay constants the solutions become identical to the standard spinning mini boson stars. For small decay constants, on the other hand, the solutions develop distinctive features. In particular, we analyse their compactness, the emergence of ergoregions, light rings and the distribution of stable and unstable equatorial timelike circular orbits, including the innermost stable circular orbit. We also establish the occurrence of violations of the strong energy condition for physical observers, for some RABSs. We observe some analogy between RABSs and spinning gravitating $Q$-balls. |
gr-qc/9612057 | Arvind Borde | Arvind Borde | Regular Black Holes and Topology Change | Nine pages. One Figure. The figure will emerge automatically if you
print via "dvips" | Phys.Rev. D55 (1997) 7615-7617 | 10.1103/PhysRevD.55.7615 | null | gr-qc | null | The conditions are clarified under which regular (i.e., singularity-free)
black holes can exist. It is shown that in a large class of spacetimes that
satisfy the weak energy condition the existence of a regular black hole
requires topology change.
| [
{
"created": "Fri, 20 Dec 1996 01:54:36 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Borde",
"Arvind",
""
]
] | The conditions are clarified under which regular (i.e., singularity-free) black holes can exist. It is shown that in a large class of spacetimes that satisfy the weak energy condition the existence of a regular black hole requires topology change. |
2302.12622 | Charalampos Theofilis | Marios Christodoulou, Fabio D'Ambrosio, Charalampos Theofilis | Geometry Transition in Spinfoams | The work presented here provides a self consistent presentation of
the technique on which the calculation of the estimate for the bounce time of
the black to white transition appeared in Ref. 2 was based | null | null | null | gr-qc quant-ph | http://creativecommons.org/licenses/by/4.0/ | We show how the fixed-spin asymptotics of the EPRL model can be used to
perform the spin-sum for spin foam amplitudes defined on fixed two-complexes
without interior faces and contracted with coherent spin-network states peaked
on a discrete simplicial geometry with macroscopic areas. We work in the
representation given in Ref. 1. We first rederive the latter in a different way
suitable for our purposes. We then extend this representation to 2-complexes
with a boundary and derive its relation to the coherent state representation.
We give the measure providing the resolution of the identity for Thiemann's
state in the twisted geometry parametrization. The above then permit us to put
everything together with other results in the literature and show how the spin
sum can be performed analytically for the regime of interest here. These
results are relevant to analytic investigations regarding the transition of a
black hole to a white hole geometry. In particular, this work gives detailed
technique that was the basis of estimate for the black to white bounce appeared
in Ref. 2. These results may also be relevant for applications of spinfoams to
investigate the possibility of a 'big bounce'.
| [
{
"created": "Fri, 24 Feb 2023 13:36:03 GMT",
"version": "v1"
}
] | 2023-02-27 | [
[
"Christodoulou",
"Marios",
""
],
[
"D'Ambrosio",
"Fabio",
""
],
[
"Theofilis",
"Charalampos",
""
]
] | We show how the fixed-spin asymptotics of the EPRL model can be used to perform the spin-sum for spin foam amplitudes defined on fixed two-complexes without interior faces and contracted with coherent spin-network states peaked on a discrete simplicial geometry with macroscopic areas. We work in the representation given in Ref. 1. We first rederive the latter in a different way suitable for our purposes. We then extend this representation to 2-complexes with a boundary and derive its relation to the coherent state representation. We give the measure providing the resolution of the identity for Thiemann's state in the twisted geometry parametrization. The above then permit us to put everything together with other results in the literature and show how the spin sum can be performed analytically for the regime of interest here. These results are relevant to analytic investigations regarding the transition of a black hole to a white hole geometry. In particular, this work gives detailed technique that was the basis of estimate for the black to white bounce appeared in Ref. 2. These results may also be relevant for applications of spinfoams to investigate the possibility of a 'big bounce'. |
1003.0344 | Nail Khusnutdinov | V.B. Bezerra, E.R. Bezerra de Mello, N.R. Khusnutdinov, S.V. Sushkov | Vacuum polarization of a massive scalar field in a wormhole spacetime | 7 pages, 5 figures | Phys.Rev.D81:084034,2010 | 10.1103/PhysRevD.81.084034 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We calculate the vacuum average value of the field square and the
stress-energy tensor of a massive scalar field, with non-minimal coupling $\xi$
to the curvature in the short-throat flat-space wormhole background. The
obtained results are not suitable for an analytical analysis and for this
reason we provide a numerical analysis for different values of the coupling
constant, $\xi$. It was shown that the vacuum polarization cannot
self-consistently support the wormhole. Otherwise, the energy-momentum tensor
does not violate the null energy condition near the throat.
| [
{
"created": "Mon, 1 Mar 2010 13:22:06 GMT",
"version": "v1"
},
{
"created": "Tue, 20 Apr 2010 04:54:53 GMT",
"version": "v2"
}
] | 2010-05-12 | [
[
"Bezerra",
"V. B.",
""
],
[
"de Mello",
"E. R. Bezerra",
""
],
[
"Khusnutdinov",
"N. R.",
""
],
[
"Sushkov",
"S. V.",
""
]
] | We calculate the vacuum average value of the field square and the stress-energy tensor of a massive scalar field, with non-minimal coupling $\xi$ to the curvature in the short-throat flat-space wormhole background. The obtained results are not suitable for an analytical analysis and for this reason we provide a numerical analysis for different values of the coupling constant, $\xi$. It was shown that the vacuum polarization cannot self-consistently support the wormhole. Otherwise, the energy-momentum tensor does not violate the null energy condition near the throat. |
gr-qc/9610004 | M. A. Clayton | M.A. Clayton | The Tetrad Frame Constraint Algebra | 19 pages, Latex2e with ams-latex style files; now even bigger | Class.Quant.Grav. 14 (1997) 1851-1864 | 10.1088/0264-9381/14/7/019 | UTPT-96-15 | gr-qc | null | It is shown via the principle of path independence that the (time gauge)
constraint algebra derived in (Class. Quantum Grav. 5 (1988) pg. 1405) for
vielbein General Relativity is a generic feature of any covariant theory
formulated in a vielbein frame. In the process of doing so, the relationship
between the coordinate and orthonormal frame algebera is made explicit.
| [
{
"created": "Wed, 2 Oct 1996 00:53:02 GMT",
"version": "v1"
},
{
"created": "Fri, 25 Oct 1996 22:14:55 GMT",
"version": "v2"
},
{
"created": "Thu, 30 Jan 1997 10:47:42 GMT",
"version": "v3"
}
] | 2009-10-28 | [
[
"Clayton",
"M. A.",
""
]
] | It is shown via the principle of path independence that the (time gauge) constraint algebra derived in (Class. Quantum Grav. 5 (1988) pg. 1405) for vielbein General Relativity is a generic feature of any covariant theory formulated in a vielbein frame. In the process of doing so, the relationship between the coordinate and orthonormal frame algebera is made explicit. |
1301.6351 | Ming-Lei Tong | Ming-Lei Tong | Relic gravitational waves in the frame of slow-roll inflation with a
power-law potential and the detection | 18 pages, 10 figures, 1 table. To match the published version. arXiv
admin note: substantial text overlap with arXiv:1206.2109 | Class. Quantum Grav. 30, 055013, 2013 | 10.1088/0264-9381/30/5/055013 | NTSC-Tong/02 | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We obtained the analytic solutions of relic gravitational waves (RGWs) for
the slow-roll inflation with a power-law form potential of the scalar field,
$V=\lambda\phi^n$. Based on a reasonable range of $n$ constrained by cosmic
microwave background (CMB) observations, we give tight constraints of the
tensor-to-scalar ratio $r$ and the inflation expansion index $\beta$ for the
fixed scalar spectral index $n_s$. Even though, the spectrum of RGWs in low
frequencies is hardly depends on any parameters, the high frequency parts will
be affected by several parameters, such as $n_s$, the reheating temperature
$T_{RH}$ and the index $\beta_s$ describing the expansion from the end of
inflation to the reheating process. We analyzed in detail all the factors which
would affect the spectrum of RGWs in high frequencies including the quantum
normalization. We found that the future GW detectors SKA, eLISA, BBO and DECIGO
are promising to catch the signals of RGWs.
Furthermore, BBO and DECIGO have the potential not only to distinguish the
spectra with different parameters but also to examine the validity of the
quantum normalization.
| [
{
"created": "Sun, 27 Jan 2013 13:55:19 GMT",
"version": "v1"
},
{
"created": "Fri, 22 Feb 2013 13:11:55 GMT",
"version": "v2"
}
] | 2015-06-12 | [
[
"Tong",
"Ming-Lei",
""
]
] | We obtained the analytic solutions of relic gravitational waves (RGWs) for the slow-roll inflation with a power-law form potential of the scalar field, $V=\lambda\phi^n$. Based on a reasonable range of $n$ constrained by cosmic microwave background (CMB) observations, we give tight constraints of the tensor-to-scalar ratio $r$ and the inflation expansion index $\beta$ for the fixed scalar spectral index $n_s$. Even though, the spectrum of RGWs in low frequencies is hardly depends on any parameters, the high frequency parts will be affected by several parameters, such as $n_s$, the reheating temperature $T_{RH}$ and the index $\beta_s$ describing the expansion from the end of inflation to the reheating process. We analyzed in detail all the factors which would affect the spectrum of RGWs in high frequencies including the quantum normalization. We found that the future GW detectors SKA, eLISA, BBO and DECIGO are promising to catch the signals of RGWs. Furthermore, BBO and DECIGO have the potential not only to distinguish the spectra with different parameters but also to examine the validity of the quantum normalization. |
1209.5239 | Muzaffer Adak | \"Ozcan Sert (Pamukkale U.) and Muzaffer Adak (Pamukkale U.) | Spinor coupling to the weak Poincare gauge theory of gravity in three
dimensions | We added a new subsection, corrected syntax errors, extended
dicussion. To be published in Phys. Rev. D | Physical Review D 86, 124033 (2012) | 10.1103/PhysRevD.86.124033 | null | gr-qc hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Minimal coupling of a Dirac field to gravity with the most general
non-propagating torsion is considered in (1+2)-dimensions. The field equations
are obtained from a lagrangian by a variational principle. The space-time
torsion is calculated algebraically in terms of a quadratic spinor condensate
plus coupling coefficients. Firstly we give circularly symmetric rotating exact
solutions that collapse to $AdS_3$ geometry in the absence of the Dirac
condensate. Secondly we investigate a BTZ-like solution.
| [
{
"created": "Mon, 24 Sep 2012 12:07:39 GMT",
"version": "v1"
},
{
"created": "Thu, 22 Nov 2012 06:38:02 GMT",
"version": "v2"
}
] | 2013-09-24 | [
[
"Sert",
"Özcan",
"",
"Pamukkale U."
],
[
"Adak",
"Muzaffer",
"",
"Pamukkale U."
]
] | Minimal coupling of a Dirac field to gravity with the most general non-propagating torsion is considered in (1+2)-dimensions. The field equations are obtained from a lagrangian by a variational principle. The space-time torsion is calculated algebraically in terms of a quadratic spinor condensate plus coupling coefficients. Firstly we give circularly symmetric rotating exact solutions that collapse to $AdS_3$ geometry in the absence of the Dirac condensate. Secondly we investigate a BTZ-like solution. |
1509.04703 | Hyerim Noh | Jai-chan Hwang and Hyerim Noh | Newtonian, post-Newtonian and Relativistic Cosmological Perturbation
Theory | 7 pages, published in Nuclear Physics B (Proc. Suppl.) | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Newtonian cosmological perturbation equations valid to full nonlinear order
are well known in the literature. Assuming the absence of the
transverse-tracefree part of the metric, we present the general relativistic
counterpart valid to full nonlinear order. The relativistic equations are
presented without taking the slicing (temporal gauge) condition. The equations
do have the proper Newtonian and first post-Newtonian limits. We also present
the relativistic pressure correction terms in the Newtonian hydrodynamic
equations.
| [
{
"created": "Tue, 15 Sep 2015 07:41:44 GMT",
"version": "v1"
}
] | 2015-09-17 | [
[
"Hwang",
"Jai-chan",
""
],
[
"Noh",
"Hyerim",
""
]
] | Newtonian cosmological perturbation equations valid to full nonlinear order are well known in the literature. Assuming the absence of the transverse-tracefree part of the metric, we present the general relativistic counterpart valid to full nonlinear order. The relativistic equations are presented without taking the slicing (temporal gauge) condition. The equations do have the proper Newtonian and first post-Newtonian limits. We also present the relativistic pressure correction terms in the Newtonian hydrodynamic equations. |
gr-qc/9706009 | Friedrich Wilhelm Hehl | F.W. Hehl, A. Mac\'ias, E.W. Mielke, Yu.N. Obukhov | On the structure of the energy-momentum and the spin currents in Dirac's
electron theory | 19 pages, latex2e, no figures, to appear in: "On Einstein's Path".
Festschrift for E. Schucking on the occasion of his 70th birthday. A. Harvey,
ed. (Springer: Berlin 1997/98) | null | null | null | gr-qc hep-th | null | We consider a classical Dirac field in flat Minkowski spacetime. We perform a
Gordon decomposition of its canonical energy-momentum and spin currents,
respectively. Thereby we find for each of these currents a convective and a
polarization piece. The polarization pieces can be expressed as exterior
covariant derivatives of the two-forms $\check M_\alpha$ and
$M_{\alpha\beta}=-M_{\beta\alpha}$, respectively. In analogy to the magnetic
moment in electrodynamics, we identify these two-forms as gravitational moments
connected with the translation group and the Lorentz group, respectively. We
point out the relation between the Gordon decomposition of the energy-momentum
current and its Belinfante-Rosenfeld symmetrization. In the non-relativistic
limit, the translational gravitational moment of the Dirac field is found to be
proportional to the spin covector of the electron.
| [
{
"created": "Tue, 3 Jun 1997 14:05:24 GMT",
"version": "v1"
}
] | 2016-08-15 | [
[
"Hehl",
"F. W.",
""
],
[
"Macías",
"A.",
""
],
[
"Mielke",
"E. W.",
""
],
[
"Obukhov",
"Yu. N.",
""
]
] | We consider a classical Dirac field in flat Minkowski spacetime. We perform a Gordon decomposition of its canonical energy-momentum and spin currents, respectively. Thereby we find for each of these currents a convective and a polarization piece. The polarization pieces can be expressed as exterior covariant derivatives of the two-forms $\check M_\alpha$ and $M_{\alpha\beta}=-M_{\beta\alpha}$, respectively. In analogy to the magnetic moment in electrodynamics, we identify these two-forms as gravitational moments connected with the translation group and the Lorentz group, respectively. We point out the relation between the Gordon decomposition of the energy-momentum current and its Belinfante-Rosenfeld symmetrization. In the non-relativistic limit, the translational gravitational moment of the Dirac field is found to be proportional to the spin covector of the electron. |
1401.4706 | Uro\v{s} Kosti\'c | Uro\v{s} Kosti\'c, Martin Horvat, Sante Carloni, Pac\^ome Delva,
Andreja Gomboc | An Autonomous Reference Frame for Relativistic GNSS | 5 pages, 3 figures, in proceedings of the 4th International
Colloquium: Scientific and Fundamental Aspects of the Galileo Programme, 4-6
December 2013, Prague, Czech Republic; removed unnecessary indices from eqs.
3,6,7 and corrected minus signs in eqs. 6 and 7 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Current GNSS systems rely on global reference frames which are fixed to the
Earth (via the ground stations) so their precision and stability in time are
limited by our knowledge of the Earth dynamics. These drawbacks could be
avoided by giving to the constellation of satellites the possibility of
constituting by itself a primary and autonomous positioning system, without any
a priori realization of a terrestrial reference frame. Our work shows that it
is possible to construct such a system, an Autonomous Basis of Coordinates, via
emission coordinates. Here we present the idea of the Autonomous Basis of
Coordinates and its implementation in the perturbed space-time of Earth, where
the motion of satellites, light propagation, and gravitational perturbations
are treated in the formalism of general relativity.
| [
{
"created": "Sun, 19 Jan 2014 17:23:06 GMT",
"version": "v1"
},
{
"created": "Fri, 24 Jan 2014 09:08:37 GMT",
"version": "v2"
}
] | 2014-01-27 | [
[
"Kostić",
"Uroš",
""
],
[
"Horvat",
"Martin",
""
],
[
"Carloni",
"Sante",
""
],
[
"Delva",
"Pacôme",
""
],
[
"Gomboc",
"Andreja",
""
]
] | Current GNSS systems rely on global reference frames which are fixed to the Earth (via the ground stations) so their precision and stability in time are limited by our knowledge of the Earth dynamics. These drawbacks could be avoided by giving to the constellation of satellites the possibility of constituting by itself a primary and autonomous positioning system, without any a priori realization of a terrestrial reference frame. Our work shows that it is possible to construct such a system, an Autonomous Basis of Coordinates, via emission coordinates. Here we present the idea of the Autonomous Basis of Coordinates and its implementation in the perturbed space-time of Earth, where the motion of satellites, light propagation, and gravitational perturbations are treated in the formalism of general relativity. |
gr-qc/0303068 | Claudio Simeone | Gaston Giribet | Brief comments on Jackiw-Teitelboim gravity coupled to Liouville theory | 14 pages, no figures. v2 References added. To be published in
Classical and Quantum Gravity. v3 typos corrected | Class.Quant.Grav. 20 (2003) 2119-2130 | 10.1088/0264-9381/20/11/312 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Jackiw-Teitelboim gravity with non-vanishing cosmological constant coupled to
Liouville theory is considered as a non-critical string on $d$ dimensional flat
spacetime. It is discussed how the presence of cosmological constant yields
additional constraints on the parameter space of the theory, even when the
conformal anomaly is independent of the cosmological constant. Such constraints
agree with the necessary conditions for the tachyon field to be a primary
--prelogarithmic-- operator of the worldsheet conformal field theory. Thus, the
linearized tachyon field equation allows to impose the diagonal condition for
the interaction term. We analyze the neutralization of the Liouville mode
induced by the coupling to the Jackiw-Teitelboim Lagrangian. The free field
prescription leads to obtain explicit expressions for three-point correlation
functions for the case of vanishing cosmological constant in terms of a product
of Shapiro-Virasoro integrals. This is a consequence of the mentioned
neutralization effect.
| [
{
"created": "Tue, 18 Mar 2003 18:59:24 GMT",
"version": "v1"
},
{
"created": "Mon, 28 Apr 2003 23:55:12 GMT",
"version": "v2"
},
{
"created": "Wed, 23 Aug 2017 21:31:44 GMT",
"version": "v3"
}
] | 2017-08-29 | [
[
"Giribet",
"Gaston",
""
]
] | Jackiw-Teitelboim gravity with non-vanishing cosmological constant coupled to Liouville theory is considered as a non-critical string on $d$ dimensional flat spacetime. It is discussed how the presence of cosmological constant yields additional constraints on the parameter space of the theory, even when the conformal anomaly is independent of the cosmological constant. Such constraints agree with the necessary conditions for the tachyon field to be a primary --prelogarithmic-- operator of the worldsheet conformal field theory. Thus, the linearized tachyon field equation allows to impose the diagonal condition for the interaction term. We analyze the neutralization of the Liouville mode induced by the coupling to the Jackiw-Teitelboim Lagrangian. The free field prescription leads to obtain explicit expressions for three-point correlation functions for the case of vanishing cosmological constant in terms of a product of Shapiro-Virasoro integrals. This is a consequence of the mentioned neutralization effect. |
gr-qc/9903030 | Wai-Mo Suen | Miguel Alcubierre, Bernd Brugmann, Mark Miller and Wai-Mo Suen | A Conformal Hyperbolic Formulation of the Einstein Equations | 4 pages | Phys.Rev.D60:064017,1999 | 10.1103/PhysRevD.60.064017 | null | gr-qc | null | We propose a re-formulation of the Einstein evolution equations that cleanly
separates the conformal degrees of freedom and the non-conformal degrees of
freedom with the latter satisfying a first order strongly hyperbolic system.
The conformal degrees of freedom are taken to be determined by the choice of
slicing and the initial data, and are regarded as given functions (along with
the lapse and the shift) in the hyperbolic part of the evolution.
We find that there is a two parameter family of hyperbolic systems for the
non-conformal degrees of freedom for a given set of trace free variables. The
two parameters are uniquely fixed if we require the system to be ``consistently
trace-free'', i.e., the time derivatives of the trace free variables remains
trace-free to the principal part, even in the presence of constraint violations
due to numerical truncation error. We show that by forming linear combinations
of the trace free variables a conformal hyperbolic system with only physical
characteristic speeds can also be constructed.
| [
{
"created": "Mon, 8 Mar 1999 21:48:53 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Alcubierre",
"Miguel",
""
],
[
"Brugmann",
"Bernd",
""
],
[
"Miller",
"Mark",
""
],
[
"Suen",
"Wai-Mo",
""
]
] | We propose a re-formulation of the Einstein evolution equations that cleanly separates the conformal degrees of freedom and the non-conformal degrees of freedom with the latter satisfying a first order strongly hyperbolic system. The conformal degrees of freedom are taken to be determined by the choice of slicing and the initial data, and are regarded as given functions (along with the lapse and the shift) in the hyperbolic part of the evolution. We find that there is a two parameter family of hyperbolic systems for the non-conformal degrees of freedom for a given set of trace free variables. The two parameters are uniquely fixed if we require the system to be ``consistently trace-free'', i.e., the time derivatives of the trace free variables remains trace-free to the principal part, even in the presence of constraint violations due to numerical truncation error. We show that by forming linear combinations of the trace free variables a conformal hyperbolic system with only physical characteristic speeds can also be constructed. |
1201.4656 | Miroslav Shaltev | Miroslav Shaltev | Coherent follow-up of Continuous Gravitational Wave candidates: minimal
required observation time | 9 pages, 3 figures, Amaldi 9 | null | 10.1088/1742-6596/363/1/012043 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive two different methods to compute the minimal required integration
time of a fully coherent follow-up of candidates produced in wide parameter
space semi-coherent searches, such as global correlation StackSlide searches
using Einstein@Home. We numerically compare these methods in terms of
integration duration and computing cost. In a Monte Carlo study we confirm that
we can achieve the required detection probability.
| [
{
"created": "Mon, 23 Jan 2012 09:51:43 GMT",
"version": "v1"
},
{
"created": "Fri, 16 Mar 2012 14:28:47 GMT",
"version": "v2"
}
] | 2013-11-26 | [
[
"Shaltev",
"Miroslav",
""
]
] | We derive two different methods to compute the minimal required integration time of a fully coherent follow-up of candidates produced in wide parameter space semi-coherent searches, such as global correlation StackSlide searches using Einstein@Home. We numerically compare these methods in terms of integration duration and computing cost. In a Monte Carlo study we confirm that we can achieve the required detection probability. |
gr-qc/0103035 | Carlo Ungarelli | M. Gasperini and C. Ungarelli | Detecting a relic background of scalar waves with LIGO | 17 pages, uses revtex | Phys.Rev. D64 (2001) 064009 | 10.1103/PhysRevD.64.064009 | null | gr-qc astro-ph hep-th | null | We discuss the possible detection of a stochastic background of massive,
non-relativistic scalar particles, through the cross correlation of the two
LIGO interferometers in the initial, enhanced and advanced configuration. If
the frequency corresponding to the mass of the scalar field lies in the
detector sensitivity band, and the non-relativistic branch of the spectrum
gives a significant contribution to energy density required to close the
Universe, we find that the scalar background can induce a non-negligible
signal, in competition with a possible signal produced by a stochastic
background of gravitational radiation.
| [
{
"created": "Mon, 12 Mar 2001 15:21:56 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Gasperini",
"M.",
""
],
[
"Ungarelli",
"C.",
""
]
] | We discuss the possible detection of a stochastic background of massive, non-relativistic scalar particles, through the cross correlation of the two LIGO interferometers in the initial, enhanced and advanced configuration. If the frequency corresponding to the mass of the scalar field lies in the detector sensitivity band, and the non-relativistic branch of the spectrum gives a significant contribution to energy density required to close the Universe, we find that the scalar background can induce a non-negligible signal, in competition with a possible signal produced by a stochastic background of gravitational radiation. |
2206.05690 | Wenkun Luo | Wen-Kun Luo, Cheng-Yong Zhang, Peng Liu, Chao Niu, and Bin Wang | Dynamical spontaneous scalarization in Einstein-Maxwell-scalar models in
anti-de Sitter spacetime | 20pages,8figures | null | 10.1103/PhysRevD.106.064036 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The phenomenon of spontaneous scalarization of charged black holes has
attracted a lot of attention. In this work, we study the dynamical process of
the spontaneous scalarization of charged black hole in asymptotically anti-de
Sitter spacetimes in Einstein-Maxwell-scalar models. Including various
non-minimal couplings between the scalar field and Maxwell field, we observe
that an initial scalar-free configuration suffers tachyonic instability and
both the scalar field and the black hole irreducible mass grow exponentially at
early times and saturate exponentially at late times. For fractional couplings,
we find that though there is negative energy distribution near the black hole
horizon, the black hole horizon area never decreases. But when the parameters
are large, the evolution endpoints of linearly unstable bald black holes will
be spacetimes with naked singularity and the cosmic censorship is violated. The
effects of the black hole charge, cosmological constant and coupling strength
on the dynamical scalarization process are studied in detail. We find that
large enough cosmological constant can prevent the spontaneous scalarization.
| [
{
"created": "Sun, 12 Jun 2022 08:06:18 GMT",
"version": "v1"
}
] | 2022-10-05 | [
[
"Luo",
"Wen-Kun",
""
],
[
"Zhang",
"Cheng-Yong",
""
],
[
"Liu",
"Peng",
""
],
[
"Niu",
"Chao",
""
],
[
"Wang",
"Bin",
""
]
] | The phenomenon of spontaneous scalarization of charged black holes has attracted a lot of attention. In this work, we study the dynamical process of the spontaneous scalarization of charged black hole in asymptotically anti-de Sitter spacetimes in Einstein-Maxwell-scalar models. Including various non-minimal couplings between the scalar field and Maxwell field, we observe that an initial scalar-free configuration suffers tachyonic instability and both the scalar field and the black hole irreducible mass grow exponentially at early times and saturate exponentially at late times. For fractional couplings, we find that though there is negative energy distribution near the black hole horizon, the black hole horizon area never decreases. But when the parameters are large, the evolution endpoints of linearly unstable bald black holes will be spacetimes with naked singularity and the cosmic censorship is violated. The effects of the black hole charge, cosmological constant and coupling strength on the dynamical scalarization process are studied in detail. We find that large enough cosmological constant can prevent the spontaneous scalarization. |
2009.02133 | Sam Patrick | Sam Patrick | On the analogy between black holes and bathtub vortices | Thesis, 165 pages, 40 figures | null | null | null | gr-qc physics.flu-dyn | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Analogical thinking is a valuable tool in theoretical physics, since it
allows us to take the understanding we have developed in one system and apply
it to another. In this thesis, we study the analogy between two seemingly
unlikely systems: rotating black holes, elusive cosmic entities that push our
theoretical understanding of modern physics to its limits, and bathtub
vortices, an occurrence so common that they can be observed on a day-to-day
basis in almost any household. Despite the clear difference between these two
systems, we argue that lessons from each can be used to learn something about
the other.
We investigate the equivalence between surface wave propagation in shallow
water and the propagation of a massless scalar field on an effective spacetime,
focussing in particular on the rotating black hole geometry sourced by a
rotating draining vortex flow. Using this analogy, we verify for the first time
that three effects predicted to occur around rotating black holes also occur in
a laboratory experiment. These are superradiance, an energy enhancement process
whereby waves extract rotational energy from the system, quasi-normal ringing,
describing the relaxation of the system toward equilibrium, and the
backreaction, which mediates the exchange of energy between fluctuations and
the background they experience.
| [
{
"created": "Fri, 4 Sep 2020 12:16:06 GMT",
"version": "v1"
}
] | 2020-09-07 | [
[
"Patrick",
"Sam",
""
]
] | Analogical thinking is a valuable tool in theoretical physics, since it allows us to take the understanding we have developed in one system and apply it to another. In this thesis, we study the analogy between two seemingly unlikely systems: rotating black holes, elusive cosmic entities that push our theoretical understanding of modern physics to its limits, and bathtub vortices, an occurrence so common that they can be observed on a day-to-day basis in almost any household. Despite the clear difference between these two systems, we argue that lessons from each can be used to learn something about the other. We investigate the equivalence between surface wave propagation in shallow water and the propagation of a massless scalar field on an effective spacetime, focussing in particular on the rotating black hole geometry sourced by a rotating draining vortex flow. Using this analogy, we verify for the first time that three effects predicted to occur around rotating black holes also occur in a laboratory experiment. These are superradiance, an energy enhancement process whereby waves extract rotational energy from the system, quasi-normal ringing, describing the relaxation of the system toward equilibrium, and the backreaction, which mediates the exchange of energy between fluctuations and the background they experience. |
gr-qc/9710046 | Burkhard Kleihaus | Abha Sood, Burkhard Kleihaus, Jutta Kunz | Limiting solutions of sequences of globally regular and black hole
solutions in SU(N)-EYMD theories | 3 pages, LaTeX, mprocl.sty and 2 ps files included, talk given in the
Hairy Black Holes session at the MG8 conference | null | null | null | gr-qc hep-th | null | Static spherically symmetric solutions in SU(N)-EYM and EYMD theories are
classified by the node numbers of their non-trivial gauge field functions. With
increasing node numbers, the solutions form sequences, tending to limiting
solutions. The limiting solutions are based on subalgebras of $su(N)$,
consisting of a neutral non-abelian part and a charged abelian part, belonging
to the Cartan subalgebra
| [
{
"created": "Wed, 8 Oct 1997 10:06:20 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Sood",
"Abha",
""
],
[
"Kleihaus",
"Burkhard",
""
],
[
"Kunz",
"Jutta",
""
]
] | Static spherically symmetric solutions in SU(N)-EYM and EYMD theories are classified by the node numbers of their non-trivial gauge field functions. With increasing node numbers, the solutions form sequences, tending to limiting solutions. The limiting solutions are based on subalgebras of $su(N)$, consisting of a neutral non-abelian part and a charged abelian part, belonging to the Cartan subalgebra |
1707.08791 | J. W. van Holten | J.W. van Holten | D = 1 supergravity and quantum cosmology | 9 pages including references; contribution to SYMPHYS XVII, Yerevan
(Armenia), July 2017 | Physics of Atomic Nuclei 81 (2018) 858 | 10.1134/S1063778818060182 | Nikhef/2017-036 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using a D = 1 supergravity framework I construct a super-Friedmann equation
for an isotropic and homogenous universe including dynamical scalar fields. In
the context of quantum theory this becomes an equation for a wave-function of
the universe of spinorial type, the Wheeler-DeWitt- Dirac equation. It is
argued that a cosmological constant breaks a certain chiral symmetry of this
equation, a symmetry in the Hilbert space of universe states, which could
protect a small cosmological constant from being affected by large quantum
corrections.
| [
{
"created": "Thu, 27 Jul 2017 09:29:30 GMT",
"version": "v1"
}
] | 2019-02-12 | [
[
"van Holten",
"J. W.",
""
]
] | Using a D = 1 supergravity framework I construct a super-Friedmann equation for an isotropic and homogenous universe including dynamical scalar fields. In the context of quantum theory this becomes an equation for a wave-function of the universe of spinorial type, the Wheeler-DeWitt- Dirac equation. It is argued that a cosmological constant breaks a certain chiral symmetry of this equation, a symmetry in the Hilbert space of universe states, which could protect a small cosmological constant from being affected by large quantum corrections. |
2405.14653 | Manuel Gonzalez-Espinoza | Manuel Gonzalez-Espinoza and Ramon Herrera | Inflation in a scalar-vector gravity theory | null | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the possibility that inflation is driven by a scalar field together
with a vector field minimally coupled to gravity. By assuming an effective
potential that incorporates both fields into the action, we explore two
distinct scenarios: one where the fields interact and another where they do
not. In this context, we find different analytical solutions to the background
scalar-vector fields dynamics during the inflationary scenario considering the
slow-roll approximation. Besides, general conditions required for these models
of two fields to be realizable are determined and discussed. From the
cosmological perturbations, we consider a local field rotation, and then we
determine these perturbations (scalar and tensor) during inflation, and we also
utilize recent cosmological observations for constraining the parameter-space
in these scalar-vector inflationary models.
| [
{
"created": "Thu, 23 May 2024 14:53:40 GMT",
"version": "v1"
}
] | 2024-05-24 | [
[
"Gonzalez-Espinoza",
"Manuel",
""
],
[
"Herrera",
"Ramon",
""
]
] | We study the possibility that inflation is driven by a scalar field together with a vector field minimally coupled to gravity. By assuming an effective potential that incorporates both fields into the action, we explore two distinct scenarios: one where the fields interact and another where they do not. In this context, we find different analytical solutions to the background scalar-vector fields dynamics during the inflationary scenario considering the slow-roll approximation. Besides, general conditions required for these models of two fields to be realizable are determined and discussed. From the cosmological perturbations, we consider a local field rotation, and then we determine these perturbations (scalar and tensor) during inflation, and we also utilize recent cosmological observations for constraining the parameter-space in these scalar-vector inflationary models. |
2102.05587 | Recai Erdem | Recai Erdem and Kemal Gultekin | Particle physics processes in cosmology through an effective Minkowski
space formulation and the limitations of the method | Some comments for further clarification of the content and the scope
of the paper are added in the light of the comments of the anonymous referee.
Typos are fixed. arXiv admin note: text overlap with arXiv:1908.08784 | null | 10.1140/epjc/s10052-021-09524-8 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We introduce a method where particle physics processes in cosmology may be
calculated by the usual perturbative flat space quantum field theory through an
effective Minkowski space description at small time intervals provided that the
running of the effective particle masses are sufficiently slow. We discuss the
necessary conditions for the applicability of this method and illustrate the
method through a simple example. This method has the advantage of avoiding the
effects of gravitational particle creation in the calculation of rates and
cross sections i.e. giving directly the rates and the cross sections due to the
scatterings or the decay processes.
| [
{
"created": "Wed, 10 Feb 2021 17:34:10 GMT",
"version": "v1"
},
{
"created": "Wed, 11 Aug 2021 15:02:09 GMT",
"version": "v2"
}
] | 2021-09-01 | [
[
"Erdem",
"Recai",
""
],
[
"Gultekin",
"Kemal",
""
]
] | We introduce a method where particle physics processes in cosmology may be calculated by the usual perturbative flat space quantum field theory through an effective Minkowski space description at small time intervals provided that the running of the effective particle masses are sufficiently slow. We discuss the necessary conditions for the applicability of this method and illustrate the method through a simple example. This method has the advantage of avoiding the effects of gravitational particle creation in the calculation of rates and cross sections i.e. giving directly the rates and the cross sections due to the scatterings or the decay processes. |
1703.06258 | Dnyaneshwar Pawar Dr | P. K. Agrawal and D. D. Pawar | Vacuum Solutions of FRW and Axially Symmetric space-time in f(R) Theory
of Gravity | Under review in Iranian Journal of Science and Technology | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the present paper an attempt has been made to study the spatially
homogeneous and isotropic FRW model and axially symmetric spacetime in f(R)
theory of gravity. We have obtained the solutions of the field equations in
vacuum. To find the solutions of axially symmetric space-time we have assumed
the relation between scale factor and scalar field and also we considered that
scalar expansion ({\theta}) in the model is proportional to shear scalar
({\sigma}). The physical behavior for both models have been discussed by using
physical parameters. The function of Ricci scalar is investigated for these
models. Key words: f(R) theory of gravity, FRW universe, Axially symmetric
space-time.
| [
{
"created": "Sat, 18 Mar 2017 06:10:13 GMT",
"version": "v1"
}
] | 2017-03-21 | [
[
"Agrawal",
"P. K.",
""
],
[
"Pawar",
"D. D.",
""
]
] | In the present paper an attempt has been made to study the spatially homogeneous and isotropic FRW model and axially symmetric spacetime in f(R) theory of gravity. We have obtained the solutions of the field equations in vacuum. To find the solutions of axially symmetric space-time we have assumed the relation between scale factor and scalar field and also we considered that scalar expansion ({\theta}) in the model is proportional to shear scalar ({\sigma}). The physical behavior for both models have been discussed by using physical parameters. The function of Ricci scalar is investigated for these models. Key words: f(R) theory of gravity, FRW universe, Axially symmetric space-time. |
2101.05964 | Suvikranth Gera | Suvikranth Gera and Sandipan Sengupta | Finite model of an electric charge | 5 pages, version matches the journal version | Phys. Rev. D 104, 044057 (2021) | 10.1103/PhysRevD.104.044057 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We set up a model of an electric charge where the noninvertible metric phase
of first order gravity supercedes the point charge singularity in a curved
spacetime. A topological interpretation of the electric charge is provided in
terms of an index defined for the degenerate spacetime solution, being closely
related to the Euler characteristic. The gravitational equations of motion at
this phase are found to be equivalent to the laws of electrostatics. The
associated field energy is finite and the geometry sourcing the charge is
regular.
| [
{
"created": "Fri, 15 Jan 2021 04:40:00 GMT",
"version": "v1"
},
{
"created": "Wed, 25 Aug 2021 07:02:27 GMT",
"version": "v2"
}
] | 2021-09-01 | [
[
"Gera",
"Suvikranth",
""
],
[
"Sengupta",
"Sandipan",
""
]
] | We set up a model of an electric charge where the noninvertible metric phase of first order gravity supercedes the point charge singularity in a curved spacetime. A topological interpretation of the electric charge is provided in terms of an index defined for the degenerate spacetime solution, being closely related to the Euler characteristic. The gravitational equations of motion at this phase are found to be equivalent to the laws of electrostatics. The associated field energy is finite and the geometry sourcing the charge is regular. |
1611.06043 | Rituparno Goswami | Dan B. Sibandze, Rituparno Goswami, Sunil D. Maharaj, Anne Marie
Nzioki, Peter K. S. Dunsby | Scalar wave scattering from Schwarzschild black holes in modified
gravity | 14 pages, 2 figures. minor changes, references added | null | 10.1140/epjc/s10052-017-4936-0 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the scattering of gravitational waves off a Schwarzschild black
hole in $f(R)$ gravity. We show that the reflection and transmission
coefficients for tensor waves are the same as in General Relativity. While the
scalar waves, which are not present in General Relativity, demonstrate
interesting features. The equation that governs these scalar waves can be
reduced to a Volterra integral equation. Analysis of this equation shows that a
larger fraction of these waves are reflected compared to what one obtains for
tensors. This may provide a novel observational signature for fourth order
gravity.
| [
{
"created": "Fri, 18 Nov 2016 11:02:05 GMT",
"version": "v1"
},
{
"created": "Fri, 25 Nov 2016 07:31:47 GMT",
"version": "v2"
}
] | 2017-09-13 | [
[
"Sibandze",
"Dan B.",
""
],
[
"Goswami",
"Rituparno",
""
],
[
"Maharaj",
"Sunil D.",
""
],
[
"Nzioki",
"Anne Marie",
""
],
[
"Dunsby",
"Peter K. S.",
""
]
] | We consider the scattering of gravitational waves off a Schwarzschild black hole in $f(R)$ gravity. We show that the reflection and transmission coefficients for tensor waves are the same as in General Relativity. While the scalar waves, which are not present in General Relativity, demonstrate interesting features. The equation that governs these scalar waves can be reduced to a Volterra integral equation. Analysis of this equation shows that a larger fraction of these waves are reflected compared to what one obtains for tensors. This may provide a novel observational signature for fourth order gravity. |
1405.7019 | Emmanuil Saridakis | Tiberiu Harko (University Coll. London), Francisco S. N. Lobo (Lisbon
U., CAAUL), Emmanuel N. Saridakis (Natl. Tech. U., Athens and Valparaiso U.,
Catolica) | Cosmology with higher-derivative matter fields | 22 pages, 8 figures, version published in Int.J.Geom.Meth.Mod.Phys | Int.J.Geom.Meth.Mod.Phys. 13 (2016), 1650102 | 10.1142/S0219887816501024 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the cosmological implications of a new class of modified
gravity, where the field equations generically include higher-order derivatives
of the matter fields, arising from the introduction of non-dynamical auxiliary
fields in the action. Imposing a flat, homogeneous and isotropic geometry we
extract the Friedmann equations, obtaining an effective dark-energy sector
containing higher derivatives of the matter energy density and pressure. For
the cases of dust, radiation, and stiff matter we analyze the cosmological
behavior, finding accelerating, de Sitter, and non-accelerating phases,
dominated by matter or dark energy. Additionally, the effective dark-energy
equation-of-state parameter can be quintessence-like,
cosmological-constant-like, or even phantom-like. The detailed study of these
scenarios may provide signatures that could distinguish them from other
candidates of modified gravity.
| [
{
"created": "Tue, 27 May 2014 19:13:08 GMT",
"version": "v1"
},
{
"created": "Thu, 30 Jun 2016 06:06:15 GMT",
"version": "v2"
}
] | 2016-07-01 | [
[
"Harko",
"Tiberiu",
"",
"University Coll. London"
],
[
"Lobo",
"Francisco S. N.",
"",
"Lisbon\n U., CAAUL"
],
[
"Saridakis",
"Emmanuel N.",
"",
"Natl. Tech. U., Athens and Valparaiso U.,\n Catolica"
]
] | We investigate the cosmological implications of a new class of modified gravity, where the field equations generically include higher-order derivatives of the matter fields, arising from the introduction of non-dynamical auxiliary fields in the action. Imposing a flat, homogeneous and isotropic geometry we extract the Friedmann equations, obtaining an effective dark-energy sector containing higher derivatives of the matter energy density and pressure. For the cases of dust, radiation, and stiff matter we analyze the cosmological behavior, finding accelerating, de Sitter, and non-accelerating phases, dominated by matter or dark energy. Additionally, the effective dark-energy equation-of-state parameter can be quintessence-like, cosmological-constant-like, or even phantom-like. The detailed study of these scenarios may provide signatures that could distinguish them from other candidates of modified gravity. |
0911.1208 | Carles Bona | C. Bona and C. Bona-Casas | Gowdy waves as a test-bed for constraint-preserving boundary conditions | 5 pages, 1 figure. Contribution to the Spanish Relativity Meeting
2009 | J.Phys.Conf.Ser.229:012022,2010 | 10.1088/1742-6596/229/1/012022 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gowdy waves, one of the standard 'apples with apples' tests, is proposed as a
test-bed for constraint-preserving boundary conditions in the non-linear
regime. As an illustration, energy-constraint preservation is separately tested
in the Z4 framework. Both algebraic conditions, derived from energy estimates,
and derivative conditions, deduced from the constraint-propagation system, are
considered. The numerical errors at the boundary are of the same order than
those at the interior points.
| [
{
"created": "Fri, 6 Nov 2009 10:04:11 GMT",
"version": "v1"
}
] | 2014-11-20 | [
[
"Bona",
"C.",
""
],
[
"Bona-Casas",
"C.",
""
]
] | Gowdy waves, one of the standard 'apples with apples' tests, is proposed as a test-bed for constraint-preserving boundary conditions in the non-linear regime. As an illustration, energy-constraint preservation is separately tested in the Z4 framework. Both algebraic conditions, derived from energy estimates, and derivative conditions, deduced from the constraint-propagation system, are considered. The numerical errors at the boundary are of the same order than those at the interior points. |
0906.3216 | Jose Natario | Filipe C. Mena, Jose Natario and Paul Tod | Formation of Higher-dimensional Topological Black Holes | 16 pages, 3 figures; v2: typos corrected, matches final published
version | Annales Henri Poincare 10:1359-1376,2010 | 10.1007/s00023-009-0013-z | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study higher dimensional gravitational collapse to topological black holes
in two steps. Firstly, we construct some (n+2)-dimensional collapsing
space-times, which include generalised Lemaitre-Tolman-Bondi-like solutions,
and we prove that these can be matched to static $\Lambda$-vacuum exterior
space-times. We then investigate the global properties of the matched solutions
which, besides black holes, may include the existence of naked singularities
and wormholes. Secondly, we consider as interiors classes of 5-dimensional
collapsing solutions built on Riemannian Bianchi IX spatial metrics matched to
radiating exteriors given by the Bizon-Chmaj-Schmidt metric. In some cases, the
data at the boundary for the exterior can be chosen to be close to the data for
the Schwarzschild solution.
| [
{
"created": "Wed, 17 Jun 2009 15:56:08 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Sep 2009 18:08:10 GMT",
"version": "v2"
}
] | 2010-02-17 | [
[
"Mena",
"Filipe C.",
""
],
[
"Natario",
"Jose",
""
],
[
"Tod",
"Paul",
""
]
] | We study higher dimensional gravitational collapse to topological black holes in two steps. Firstly, we construct some (n+2)-dimensional collapsing space-times, which include generalised Lemaitre-Tolman-Bondi-like solutions, and we prove that these can be matched to static $\Lambda$-vacuum exterior space-times. We then investigate the global properties of the matched solutions which, besides black holes, may include the existence of naked singularities and wormholes. Secondly, we consider as interiors classes of 5-dimensional collapsing solutions built on Riemannian Bianchi IX spatial metrics matched to radiating exteriors given by the Bizon-Chmaj-Schmidt metric. In some cases, the data at the boundary for the exterior can be chosen to be close to the data for the Schwarzschild solution. |
2104.05419 | Gautham Varma K | Lawrence Paul Horwitz, Vishnu S Namboothiri, Gautham Varma K, Asher
Yahalom, Yossi Strauss, Jacob Levitan | Raychaudhuri Equation,Geometrical Flows and Geometrical Entropy | null | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Raychaudhuri equation is derived by assuming geometric flow in spacetime M of
n+1 dimensions. The equation turns into a harmonic oscillator form under
suitable transformations.Thereby a relation between geometrical entropy and
mean geodesic deviation is established. This has a connection to chaos theory
where the trajectories diverge exponentially. We discuss its application to
cosmology and black holes. Thus we present a connection between chaos theory
and general relativity.
| [
{
"created": "Mon, 12 Apr 2021 12:52:01 GMT",
"version": "v1"
}
] | 2021-04-13 | [
[
"Horwitz",
"Lawrence Paul",
""
],
[
"Namboothiri",
"Vishnu S",
""
],
[
"K",
"Gautham Varma",
""
],
[
"Yahalom",
"Asher",
""
],
[
"Strauss",
"Yossi",
""
],
[
"Levitan",
"Jacob",
""
]
] | Raychaudhuri equation is derived by assuming geometric flow in spacetime M of n+1 dimensions. The equation turns into a harmonic oscillator form under suitable transformations.Thereby a relation between geometrical entropy and mean geodesic deviation is established. This has a connection to chaos theory where the trajectories diverge exponentially. We discuss its application to cosmology and black holes. Thus we present a connection between chaos theory and general relativity. |
gr-qc/9709080 | Paulo Rodrigues Lima Vargas Moniz | P. V. Moniz (DAMTP, U. Cambridge) | Wave Function for the Reissner-Nordstr\"om Black-Hole | 13 pages, LaTeX | Mod.Phys.Lett. A12 (1997) 1491-1505 | 10.1142/S0217732397001527 | DAMTP R/97/23 | gr-qc hep-th | null | We study the quantum behaviour of Reissner-Nordstr\"om (RN) black-holes
interacting with a complex scalar field. A Maxwell field is also present. Our
analysis is based on M. Pollock's method and is characterized by solving a
Wheeler-DeWitt equation in the proximity of an apparent horizon of the RN
space-time. Subsequently, we obtain a wave-function $\Psi_{RN}[M, Q]$
representing the RN black-hole when its charge, $\mid Q \mid$, is small in
comparison with its mass, $M$. We then compare quantum-mechanically the cases
of $(i)$ $Q = 0$ and $(ii)$ $M \geq \mid Q \mid \neq 0 $. A special emphasis is
given to the evolution of the mass-charge rate affected by Hawking radiation.
| [
{
"created": "Tue, 30 Sep 1997 09:15:22 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Moniz",
"P. V.",
"",
"DAMTP, U. Cambridge"
]
] | We study the quantum behaviour of Reissner-Nordstr\"om (RN) black-holes interacting with a complex scalar field. A Maxwell field is also present. Our analysis is based on M. Pollock's method and is characterized by solving a Wheeler-DeWitt equation in the proximity of an apparent horizon of the RN space-time. Subsequently, we obtain a wave-function $\Psi_{RN}[M, Q]$ representing the RN black-hole when its charge, $\mid Q \mid$, is small in comparison with its mass, $M$. We then compare quantum-mechanically the cases of $(i)$ $Q = 0$ and $(ii)$ $M \geq \mid Q \mid \neq 0 $. A special emphasis is given to the evolution of the mass-charge rate affected by Hawking radiation. |
1506.08273 | Vasilis Oikonomou | J. Haro, A.N. Makarenko, A.N. Myagky, S. D. Odintsov, V.K. Oikonomou | Bounce Loop Quantum Cosmology Corrected Gauss-Bonnet Gravity | Revised version, to appear in PRD | Phys. Rev. D 92, 124026 (2015) | 10.1103/PhysRevD.92.124026 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We develop a Gauss-Bonnet extension of Loop Quantum Cosmology, by introducing
holonomy corrections in modified $F(\mathcal{G})$ theories of gravity. Within
the context of our formalism, we provide a perturbative expansion in the
critical density, a parameter characteristic of Loop Quantum Gravity theories,
and we result in having leading order corrections to the classical
$F(\mathcal{G})$ theories of gravity. After extensively discussing the
formalism, we present a reconstruction method that makes possible to find the
Loop Quantum Cosmology corrected $F(\mathcal{G})$ theory that can realize
various cosmological scenarios. Specifically, we studied exponential and
power-law bouncing cosmologies, emphasizing on the behavior near the bouncing
point and in some cases, the behavior for all the values of the cosmic time is
obtained. We exemplify our theoretical constructions by using bouncing
cosmologies, and we investigate which Loop Quantum Cosmology corrected
Gauss-Bonnet modified gravities can successfully realize such cosmologies.
| [
{
"created": "Sat, 27 Jun 2015 09:40:30 GMT",
"version": "v1"
},
{
"created": "Mon, 16 Nov 2015 15:25:35 GMT",
"version": "v2"
}
] | 2015-12-16 | [
[
"Haro",
"J.",
""
],
[
"Makarenko",
"A. N.",
""
],
[
"Myagky",
"A. N.",
""
],
[
"Odintsov",
"S. D.",
""
],
[
"Oikonomou",
"V. K.",
""
]
] | We develop a Gauss-Bonnet extension of Loop Quantum Cosmology, by introducing holonomy corrections in modified $F(\mathcal{G})$ theories of gravity. Within the context of our formalism, we provide a perturbative expansion in the critical density, a parameter characteristic of Loop Quantum Gravity theories, and we result in having leading order corrections to the classical $F(\mathcal{G})$ theories of gravity. After extensively discussing the formalism, we present a reconstruction method that makes possible to find the Loop Quantum Cosmology corrected $F(\mathcal{G})$ theory that can realize various cosmological scenarios. Specifically, we studied exponential and power-law bouncing cosmologies, emphasizing on the behavior near the bouncing point and in some cases, the behavior for all the values of the cosmic time is obtained. We exemplify our theoretical constructions by using bouncing cosmologies, and we investigate which Loop Quantum Cosmology corrected Gauss-Bonnet modified gravities can successfully realize such cosmologies. |
2209.02757 | Rahul Kashyap | Rahul Kashyap, Arnab Dhani, Bangalore Sathyaprakash | Systematic errors due to quasi-universal relations in binary neutron
stars and their correction for unbiased model selection | accepted PRD | Phys. Rev. D 106, 123001 Published 1 December 2022 | 10.1103/PhysRevD.106.123001 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Inference of the equation-of-state (EoS) of dense nuclear matter in
neutron-star cores is a principal science goal of X-ray and gravitational-wave
observations of neutron stars. In particular, gravitational-wave observations
provide an independent probe of the properties of bulk matter in neutron star
cores that can then be used to compare with theoretically derived equations of
state. In this paper, we quantify the systematic errors arising from the
application of EoS-independent \emph{quasi-universal relations} in the
estimation of neutron star tidal deformabilities and radii from
gravitational-wave measurements and introduce a strategy to correct for the
systematic biases in the inferred radii. We apply this method to a simulated
population of events expected to be observed by future upgrades of current
detectors and the next-generation of ground-based observatories. We show that
our approach can accurately correct for the systematic biases arising from
approximate universal relations in the mass-radius curves of neutron stars.
Using the posterior distributions of the mass and radius for the simulated
population we infer the underlying EoS with a good degree of precision. Our
method revives the possibility of using the universal relations for rapid
Bayesian model selection of dense matter EoS in gravitational-wave
observations.
| [
{
"created": "Tue, 6 Sep 2022 18:23:49 GMT",
"version": "v1"
},
{
"created": "Mon, 23 Jan 2023 19:04:11 GMT",
"version": "v2"
}
] | 2023-01-25 | [
[
"Kashyap",
"Rahul",
""
],
[
"Dhani",
"Arnab",
""
],
[
"Sathyaprakash",
"Bangalore",
""
]
] | Inference of the equation-of-state (EoS) of dense nuclear matter in neutron-star cores is a principal science goal of X-ray and gravitational-wave observations of neutron stars. In particular, gravitational-wave observations provide an independent probe of the properties of bulk matter in neutron star cores that can then be used to compare with theoretically derived equations of state. In this paper, we quantify the systematic errors arising from the application of EoS-independent \emph{quasi-universal relations} in the estimation of neutron star tidal deformabilities and radii from gravitational-wave measurements and introduce a strategy to correct for the systematic biases in the inferred radii. We apply this method to a simulated population of events expected to be observed by future upgrades of current detectors and the next-generation of ground-based observatories. We show that our approach can accurately correct for the systematic biases arising from approximate universal relations in the mass-radius curves of neutron stars. Using the posterior distributions of the mass and radius for the simulated population we infer the underlying EoS with a good degree of precision. Our method revives the possibility of using the universal relations for rapid Bayesian model selection of dense matter EoS in gravitational-wave observations. |
1106.5183 | Chen Songbai | Songbai Chen, Jiliang Jing | Thin accretion disk around a Kaluza-Klein black hole with squashed
horizons | 11pages, 4 figures, Accepted for publication in PLB | Phys. Lett. B 704 (2011) 641 | 10.1016/j.physletb.2011.09.071 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the accretion process in the thin disk around a squashed
Kaluza-Klein black hole and probe the effects of the extra dimensional scale
$\rho_0$ on the physical properties of the disk. Our results show that with the
increase of the parameter $\rho_0$, the energy flux, the conversion efficiency,
the radiation temperature, the spectra luminosity and the spectra cut-off
frequency of the thin accretion disk decrease, but the inner border of the disk
increases. This implies that the extra dimension scale imprints in the mass
accretion process in the disk.
| [
{
"created": "Sun, 26 Jun 2011 02:41:58 GMT",
"version": "v1"
},
{
"created": "Sun, 18 Sep 2011 12:21:16 GMT",
"version": "v2"
}
] | 2015-05-28 | [
[
"Chen",
"Songbai",
""
],
[
"Jing",
"Jiliang",
""
]
] | We study the accretion process in the thin disk around a squashed Kaluza-Klein black hole and probe the effects of the extra dimensional scale $\rho_0$ on the physical properties of the disk. Our results show that with the increase of the parameter $\rho_0$, the energy flux, the conversion efficiency, the radiation temperature, the spectra luminosity and the spectra cut-off frequency of the thin accretion disk decrease, but the inner border of the disk increases. This implies that the extra dimension scale imprints in the mass accretion process in the disk. |
gr-qc/0508126 | Francesco Cianfrani dr | F. Cianfrani, A. Marrocco, G. Montani | Gauge theories as a geometrical issue of a Kaluza-Klein framework | 37 pages, no figures | Int.J.Mod.Phys. D14 (2005) 1195-1231 | 10.1142/S0218271805006900 | null | gr-qc hep-th | null | We present a geometrical unification theory in a Kaluza-Klein approach that
achieve the geometrization of a generic gauge theory bosonic component.
We show how it is possible to derive the gauge charge conservation from the
invariance of the model under extra-dimensional translations and to geometrize
gauge connections for spinors, thus we can introduce the matter just by free
spinorial fields. Then, we present the applications to i)a pentadimensional
manifold $V^{4}\otimes S^{1}$, so reproducing the original Kaluza-Klein theory,
unless some extensions related to the rule of the scalar field contained in the
metric and the introduction of matter by spinors with a phase dependence from
the fifth coordinate, ii)a seven-dimensional manifold $V^{4}\otimes
S^{1}\otimes S^{2}$, in which we geometrize the electro-weak model by
introducing two spinors for any leptonic family and quark generation and a
scalar field with two components with opposite hypercharge, responsible of
spontaneous symmetry breaking.
| [
{
"created": "Wed, 31 Aug 2005 15:28:56 GMT",
"version": "v1"
},
{
"created": "Fri, 11 Nov 2005 13:21:09 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Cianfrani",
"F.",
""
],
[
"Marrocco",
"A.",
""
],
[
"Montani",
"G.",
""
]
] | We present a geometrical unification theory in a Kaluza-Klein approach that achieve the geometrization of a generic gauge theory bosonic component. We show how it is possible to derive the gauge charge conservation from the invariance of the model under extra-dimensional translations and to geometrize gauge connections for spinors, thus we can introduce the matter just by free spinorial fields. Then, we present the applications to i)a pentadimensional manifold $V^{4}\otimes S^{1}$, so reproducing the original Kaluza-Klein theory, unless some extensions related to the rule of the scalar field contained in the metric and the introduction of matter by spinors with a phase dependence from the fifth coordinate, ii)a seven-dimensional manifold $V^{4}\otimes S^{1}\otimes S^{2}$, in which we geometrize the electro-weak model by introducing two spinors for any leptonic family and quark generation and a scalar field with two components with opposite hypercharge, responsible of spontaneous symmetry breaking. |
1901.04674 | Sanved Kolekar | Kajol Paithankar and Sanved Kolekar | Bound on Rindler trajectories in Black Hole spacetime | v1. 24 Pages, 9 Figures v2. some discussion added, matches published
version | Phys. Rev. D 99, 064012 (2019) | 10.1103/PhysRevD.99.064012 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate radial Rindler trajectories in a static spherically symmetric
black hole spacetime. We assume the trajectory to remain linearly uniformly
accelerated throughout its motion, in the sense of the curved spacetime
generalisation of the Letaw-Frenet equations. For the Schwarzschild spacetime,
we arrive at a bound on the magnitude of the acceleration $|a|$ for radially
inward moving trajectories, in terms of the mass $M$ of the black hole given by
$|a| \leq 1/(\sqrt{27} M)$ for a particular choice of asymptotic initial data
$h$, such that, for acceleration $|a|$ greater than the bound value, the
linearly uniformly accelerated trajectory always falls into the black hole. For
$|a|$ satisfying the bound, there is a minimum radius or the distance of
closest approach for the radial linearly uniformly accelerated trajectory to
escape back to infinity. However, this distance of closest approach is found to
approach its lowest value of $r_b = 3M $, greater than the Schwarzschild radius
of the black hole, when the bound, $|a| = 1/( \sqrt{27}M)$ is saturated. We
further show that a finite bound on the value of acceleration, $ |a| \leq
B(M,h)$ and a corresponding distance of closest approach $r_{b} > 2M$ always
exists, for all finite asymptotic initial data $h$.
| [
{
"created": "Tue, 15 Jan 2019 06:24:46 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Mar 2019 12:51:17 GMT",
"version": "v2"
}
] | 2019-03-28 | [
[
"Paithankar",
"Kajol",
""
],
[
"Kolekar",
"Sanved",
""
]
] | We investigate radial Rindler trajectories in a static spherically symmetric black hole spacetime. We assume the trajectory to remain linearly uniformly accelerated throughout its motion, in the sense of the curved spacetime generalisation of the Letaw-Frenet equations. For the Schwarzschild spacetime, we arrive at a bound on the magnitude of the acceleration $|a|$ for radially inward moving trajectories, in terms of the mass $M$ of the black hole given by $|a| \leq 1/(\sqrt{27} M)$ for a particular choice of asymptotic initial data $h$, such that, for acceleration $|a|$ greater than the bound value, the linearly uniformly accelerated trajectory always falls into the black hole. For $|a|$ satisfying the bound, there is a minimum radius or the distance of closest approach for the radial linearly uniformly accelerated trajectory to escape back to infinity. However, this distance of closest approach is found to approach its lowest value of $r_b = 3M $, greater than the Schwarzschild radius of the black hole, when the bound, $|a| = 1/( \sqrt{27}M)$ is saturated. We further show that a finite bound on the value of acceleration, $ |a| \leq B(M,h)$ and a corresponding distance of closest approach $r_{b} > 2M$ always exists, for all finite asymptotic initial data $h$. |
gr-qc/9703082 | Edgardo S. Cheb-Terrab | E.S. Cheb-Terrab (1 and 2), L.G.S. Duarte (1), L.A.C.P. da Mota (1)
((1) SCG/Theor.Phys, UERJ-Brazil, (2) SCG/Fac.Math, U.Waterloo-Canada) | Computer Algebra Solving of Second Order ODEs Using Symmetry Methods | 24 pages, LaTeX, Soft-package (On-Line help) and sample MapleV
sessions available at: http://dft.if.uerj.br/odetools.htm or
http://lie.uwaterloo.ca/odetools.htm | Computer Physics Communications 108 (1998) 90 | 10.1016/S0010-4655(97)00132-X | null | gr-qc | null | An update of the ODEtools Maple package, for the analytical solving of 1st
and 2nd order ODEs using Lie group symmetry methods, is presented. The set of
routines includes an ODE-solver and user-level commands realizing most of the
relevant steps of the symmetry scheme. The package also includes commands for
testing the returned results, and for classifying 1st and 2nd order ODEs.
| [
{
"created": "Thu, 27 Mar 1997 12:20:16 GMT",
"version": "v1"
},
{
"created": "Fri, 29 May 1998 00:27:54 GMT",
"version": "v2"
}
] | 2009-10-30 | [
[
"Cheb-Terrab",
"E. S.",
"",
"1 and 2"
],
[
"Duarte",
"L. G. S.",
"",
"SCG/Theor.Phys, UERJ-Brazil"
],
[
"da Mota",
"L. A. C. P.",
"",
"SCG/Theor.Phys, UERJ-Brazil"
]
] | An update of the ODEtools Maple package, for the analytical solving of 1st and 2nd order ODEs using Lie group symmetry methods, is presented. The set of routines includes an ODE-solver and user-level commands realizing most of the relevant steps of the symmetry scheme. The package also includes commands for testing the returned results, and for classifying 1st and 2nd order ODEs. |
2312.11998 | Valentin Boyanov | Valentin Boyanov, Vitor Cardoso, Kyriakos Destounis, Jos\'e Luis
Jaramillo, Rodrigo Panosso Macedo | Structural aspects of the anti-de Sitter black hole pseudospectrum | 20 pages, 8 figures; v2 includes minor changes | null | 10.1103/PhysRevD.109.064068 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Black holes in anti-de Sitter spacetime provide an important testing ground
for both gravitational and field-theoretic phenomena. In particular, the study
of perturbations can be useful to further our understanding regarding certain
physical processes, such as superradiance, or the dynamics of strongly coupled
conformal field theories through the holographic principle. In this work we
continue our systematic study of the ultraviolet instabilities of black-hole
quasinormal modes, built on the characterization of the latter as eigenvalues
of a (spectrally unstable) non-selfadjoint operator and using the
pseudospectrum as a main analysis tool, extending our previous studies in the
asymptotically flat setting to Anti-de Sitter asymptotics. Very importantly,
this step provides a singularly well-suited probe into some of the key
structural aspects of the pseudospectrum. This is a consequence of the specific
features of the Schwarzschild-anti-de Sitter geometry, together with the
existence of a sound characterization by Warnick of quasinormal modes as
eigenvalues, that is still absent in asymptotic flatness. This work focuses on
such structural aspects, with an emphasis on the convergence issues of the
pseudospectrum and, in particular, the comparison between the hyperboloidal and
null slicing cases. As a physical by-product of this structural analysis we
assess, in particular, the spectral stability of purely imaginary
``hydrodynamic" modes, which appear for axial gravitational perturbations, that
become dominant when the black-hole horizon is larger than the anti-de Sitter
radius. We find that their spectral stability, under perturbations, depends on
how close they are to the real axis, or conversely how distant they are from
the first oscillatory overtone.
| [
{
"created": "Tue, 19 Dec 2023 09:40:36 GMT",
"version": "v1"
},
{
"created": "Tue, 26 Mar 2024 14:32:01 GMT",
"version": "v2"
}
] | 2024-03-27 | [
[
"Boyanov",
"Valentin",
""
],
[
"Cardoso",
"Vitor",
""
],
[
"Destounis",
"Kyriakos",
""
],
[
"Jaramillo",
"José Luis",
""
],
[
"Macedo",
"Rodrigo Panosso",
""
]
] | Black holes in anti-de Sitter spacetime provide an important testing ground for both gravitational and field-theoretic phenomena. In particular, the study of perturbations can be useful to further our understanding regarding certain physical processes, such as superradiance, or the dynamics of strongly coupled conformal field theories through the holographic principle. In this work we continue our systematic study of the ultraviolet instabilities of black-hole quasinormal modes, built on the characterization of the latter as eigenvalues of a (spectrally unstable) non-selfadjoint operator and using the pseudospectrum as a main analysis tool, extending our previous studies in the asymptotically flat setting to Anti-de Sitter asymptotics. Very importantly, this step provides a singularly well-suited probe into some of the key structural aspects of the pseudospectrum. This is a consequence of the specific features of the Schwarzschild-anti-de Sitter geometry, together with the existence of a sound characterization by Warnick of quasinormal modes as eigenvalues, that is still absent in asymptotic flatness. This work focuses on such structural aspects, with an emphasis on the convergence issues of the pseudospectrum and, in particular, the comparison between the hyperboloidal and null slicing cases. As a physical by-product of this structural analysis we assess, in particular, the spectral stability of purely imaginary ``hydrodynamic" modes, which appear for axial gravitational perturbations, that become dominant when the black-hole horizon is larger than the anti-de Sitter radius. We find that their spectral stability, under perturbations, depends on how close they are to the real axis, or conversely how distant they are from the first oscillatory overtone. |
1005.2073 | Lorenzo Iorio | Lorenzo Iorio | How accurate is the cancelation of the first even zonal harmonic of the
geopotential in the present and future LAGEOS-based Lense-Thirring tests? | LaTex2e, 12 pages, 3 tables, no figures. Final version matching the
one at press in General Relativity and Gravitation (GRG). Some typos fixed
and links updated | Gen.Rel.Grav.43:1697-1706,2011 | 10.1007/s10714-011-1151-4 | null | gr-qc astro-ph.EP physics.geo-ph physics.space-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The strategy followed so far in the performed or proposed tests of the
general relativistic Lense-Thirring effect in the gravitational field of the
Earth with laser-ranged satellites of LAGEOS type relies upon the cancelation
of the disturbing huge precessions induced by the first even zonal harmonic
coefficient J_2 of the multipolar expansion of the Newtonian part of the
terrestrial gravitational potential by means of suitably designed linear
combinations of the nodes \Omega of more than one spacecraft. Actually, such a
removal does depend on the accuracy with which the coefficients of the
combinations adopted can be realistically known. Uncertainties of the order of
2 cm in the semimajor axes a and 0.5 milliarcseconds in the inclinations I of
LAGEOS and LAGEOS II, entering the expression of the coefficient c_1 of the
combination of their nodes used so far, yield an uncertainty \delta c_1 = 1.30
10^-8. It gives an imperfectly canceled J_2 signal of 10.8 milliarcseconds per
year corresponding to 23% of the Lense-Thirring signature. Uncertainties of the
order of 10-30 microarcseconds in the inclinations yield \delta c_1=7.9 10^-9
which corresponds to an uncanceled J_2 signature of 6.5 milliarcseconds per
year, i.e. 14% of the Lense-Thirring signal. Concerning a future LAGEOS-LAGEOS
II-LARES combination with coefficients k_1 and k_2, the same uncertainties in a
and the less accurate uncertainties in I as before yield \delta k_1=1.1 10^-8,
\delta k_2=2 10^-9; they imply a residual J_2 combined precession of 14.7
milliarcseconds per year corresponding to 29% of the Lense-Thirring trend.
Uncertainties in the inclinations at about 10 microarcseconds level give \delta
k_1=5 10^-9, \delta k_2 = 2 10^-9; the uncanceled J_2 effect is 7.9
milliarcseconds per year, i.e. 16% of the relativistic effect.
| [
{
"created": "Wed, 12 May 2010 12:41:50 GMT",
"version": "v1"
},
{
"created": "Tue, 25 May 2010 15:54:51 GMT",
"version": "v2"
},
{
"created": "Mon, 17 Jan 2011 19:31:39 GMT",
"version": "v3"
},
{
"created": "Thu, 3 Feb 2011 18:40:24 GMT",
"version": "v4"
}
] | 2011-05-06 | [
[
"Iorio",
"Lorenzo",
""
]
] | The strategy followed so far in the performed or proposed tests of the general relativistic Lense-Thirring effect in the gravitational field of the Earth with laser-ranged satellites of LAGEOS type relies upon the cancelation of the disturbing huge precessions induced by the first even zonal harmonic coefficient J_2 of the multipolar expansion of the Newtonian part of the terrestrial gravitational potential by means of suitably designed linear combinations of the nodes \Omega of more than one spacecraft. Actually, such a removal does depend on the accuracy with which the coefficients of the combinations adopted can be realistically known. Uncertainties of the order of 2 cm in the semimajor axes a and 0.5 milliarcseconds in the inclinations I of LAGEOS and LAGEOS II, entering the expression of the coefficient c_1 of the combination of their nodes used so far, yield an uncertainty \delta c_1 = 1.30 10^-8. It gives an imperfectly canceled J_2 signal of 10.8 milliarcseconds per year corresponding to 23% of the Lense-Thirring signature. Uncertainties of the order of 10-30 microarcseconds in the inclinations yield \delta c_1=7.9 10^-9 which corresponds to an uncanceled J_2 signature of 6.5 milliarcseconds per year, i.e. 14% of the Lense-Thirring signal. Concerning a future LAGEOS-LAGEOS II-LARES combination with coefficients k_1 and k_2, the same uncertainties in a and the less accurate uncertainties in I as before yield \delta k_1=1.1 10^-8, \delta k_2=2 10^-9; they imply a residual J_2 combined precession of 14.7 milliarcseconds per year corresponding to 29% of the Lense-Thirring trend. Uncertainties in the inclinations at about 10 microarcseconds level give \delta k_1=5 10^-9, \delta k_2 = 2 10^-9; the uncanceled J_2 effect is 7.9 milliarcseconds per year, i.e. 16% of the relativistic effect. |
gr-qc/9803028 | Michele Maggiore | Michele Maggiore | High-Energy Physics with Gravitational-Wave Experiments | 26 pages, Latex, 1 figure | null | null | IFUP-TH/58-97, VIR-NOT-PIS-1390-113 | gr-qc astro-ph hep-ph hep-th | null | We discuss the possible relevance of gravitational-wave (GW) experiments for
physics at very high energy. We examine whether, from the experience gained
with the computations of various specific relic GW backgrounds, we can extract
statements and order of magnitude estimates that are as much as possible
model-independent, and we try to distinguish between general conclusions and
results related to specific cosmological mechanisms. We examine the statement
that the Virgo/LIGO experiments probe the Universe at temperatures $T\sim
10^{7}-10^{10}$ GeV (or timescales $t\sim 10^{-20}-10^{-26}$ sec) and we
consider the possibility that they could actually probe the Universe at much
higher energy scales, including the typical scales of grand unification, string
theory and quantum gravity. We consider possible scenarios, depending on how
the inflationary paradigm is implemented. We discuss the prospects for
detection with present and planned experiments. In particular, a second Virgo
interferometer correlated with the planned one, and located within a few tens
of kilometers from the first, could reach an interesting sensitivity for
stochastic GWs of cosmological origin.
| [
{
"created": "Sat, 7 Mar 1998 11:38:58 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Maggiore",
"Michele",
""
]
] | We discuss the possible relevance of gravitational-wave (GW) experiments for physics at very high energy. We examine whether, from the experience gained with the computations of various specific relic GW backgrounds, we can extract statements and order of magnitude estimates that are as much as possible model-independent, and we try to distinguish between general conclusions and results related to specific cosmological mechanisms. We examine the statement that the Virgo/LIGO experiments probe the Universe at temperatures $T\sim 10^{7}-10^{10}$ GeV (or timescales $t\sim 10^{-20}-10^{-26}$ sec) and we consider the possibility that they could actually probe the Universe at much higher energy scales, including the typical scales of grand unification, string theory and quantum gravity. We consider possible scenarios, depending on how the inflationary paradigm is implemented. We discuss the prospects for detection with present and planned experiments. In particular, a second Virgo interferometer correlated with the planned one, and located within a few tens of kilometers from the first, could reach an interesting sensitivity for stochastic GWs of cosmological origin. |
gr-qc/0401077 | Jian Qi Shen | Jian Qi Shen | Comoving suppression mechanism and cosmological constant problem | 4 pages, Latex | null | null | null | gr-qc | null | In this paper, we assume that the observer is fixed in a comoving frame of
reference with $g_{00}=\frac{\lambda}{\Lambda}$, where $\lambda$ and $\Lambda$
denote the comoving parameter and the cosmological constant, respectively. By
using the {\it comoving suppression mechanism} and {\it Mach's principle} (the
latter of which is used to determine the comoving parameter $\lambda$), we
calculate the vacuum energy density of quantum fluctuation field in the
above-mentioned comoving frame of reference. It is shown that in such a
comoving frame of reference, the cosmological constant will greatly decrease by
many orders of magnitude (if Mach's principle is applied to this calculation,
then it will be shown that $\Lambda$ is reduced by about 120 orders of
magnitude). Additionally, we briefly discuss the related topics such as the
varying observed speed of light ($\frac{{\rm d}c}{{\rm d}t}={\mathcal
O}(10^{-9}{\rm m/s}^{2})$) and the mystery of anomalous acceleration ($\sim
10^{-9}{\rm m/s}^{2}$) acquired by the Pioneer 10/11, Galileo and Ulysses
spacecrafts.
| [
{
"created": "Sat, 17 Jan 2004 09:08:17 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Shen",
"Jian Qi",
""
]
] | In this paper, we assume that the observer is fixed in a comoving frame of reference with $g_{00}=\frac{\lambda}{\Lambda}$, where $\lambda$ and $\Lambda$ denote the comoving parameter and the cosmological constant, respectively. By using the {\it comoving suppression mechanism} and {\it Mach's principle} (the latter of which is used to determine the comoving parameter $\lambda$), we calculate the vacuum energy density of quantum fluctuation field in the above-mentioned comoving frame of reference. It is shown that in such a comoving frame of reference, the cosmological constant will greatly decrease by many orders of magnitude (if Mach's principle is applied to this calculation, then it will be shown that $\Lambda$ is reduced by about 120 orders of magnitude). Additionally, we briefly discuss the related topics such as the varying observed speed of light ($\frac{{\rm d}c}{{\rm d}t}={\mathcal O}(10^{-9}{\rm m/s}^{2})$) and the mystery of anomalous acceleration ($\sim 10^{-9}{\rm m/s}^{2}$) acquired by the Pioneer 10/11, Galileo and Ulysses spacecrafts. |
gr-qc/0408087 | Veronika Kurbanova | Alexander Balakin and Veronika Kurbanova | Anomalous Polarization-Curvature Interaction in a Gravitational-Wave
Field | 9 pages, no figures | Grav.Cosmol. 10 (2004) 98-106 | null | null | gr-qc astro-ph hep-ph hep-th | null | An exact solution to the dynamic equations for a massive boson traveling in a
pp-wave gravitational background under the influence of the force induced by
curvature, is presented. We focus on the effect of anomalous
polarization-curvature interaction and consider models in which the coupling
constant of such an interaction is treated to be either a deterministic
quantity or a random variable.
| [
{
"created": "Thu, 26 Aug 2004 13:53:21 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Balakin",
"Alexander",
""
],
[
"Kurbanova",
"Veronika",
""
]
] | An exact solution to the dynamic equations for a massive boson traveling in a pp-wave gravitational background under the influence of the force induced by curvature, is presented. We focus on the effect of anomalous polarization-curvature interaction and consider models in which the coupling constant of such an interaction is treated to be either a deterministic quantity or a random variable. |
0907.3180 | Kuang Xiaomei | Xiao-Mei Kuang, Yi Ling | Viscous gravitational aether and the cosmological constant problem | 12 pages, 2 figures | JCAP 0910:024,2009 | 10.1088/1475-7516/2009/10/024 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently a notion of gravitational aether is advocated to solve the
cosmological constant problem.Through the modification of the source of gravity
one finds that the effective Newton's constant is source dependent so as to
provide a simple but consistent way to decouple gravity from the vacuum
energy.However,in the original paper the ratio of the effective Newton's
constants for pressureless dust and radiation has an upper bound which is
0.75.In this paper we propose a scheme to loose this bound by introducing a
bulk viscosity for the gravitational aether,and expect this improvement will
provide more space for matching predictions from this theoretical programm with
observational constraints.
| [
{
"created": "Sat, 18 Jul 2009 08:43:19 GMT",
"version": "v1"
},
{
"created": "Thu, 29 Oct 2009 08:46:38 GMT",
"version": "v2"
}
] | 2009-11-09 | [
[
"Kuang",
"Xiao-Mei",
""
],
[
"Ling",
"Yi",
""
]
] | Recently a notion of gravitational aether is advocated to solve the cosmological constant problem.Through the modification of the source of gravity one finds that the effective Newton's constant is source dependent so as to provide a simple but consistent way to decouple gravity from the vacuum energy.However,in the original paper the ratio of the effective Newton's constants for pressureless dust and radiation has an upper bound which is 0.75.In this paper we propose a scheme to loose this bound by introducing a bulk viscosity for the gravitational aether,and expect this improvement will provide more space for matching predictions from this theoretical programm with observational constraints. |
0811.0188 | Jonathan R. Gair | Jonathan R Gair | Probing black holes at low redshift using LISA EMRI observations | 14 pages, 5 figures, accepted for publication in Class. Quantum Grav.
(proceedings of 7th LISA Symposium); v2 includes several revisions in
response to referees' comments plus results for a pessimistic detector
configuration | Class. Quantum Grav. 26 094034 (2009) | 10.1088/0264-9381/26/9/094034 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | One of the most exciting potential sources of gravitational waves for the
Laser Interferometer Space Antenna (LISA) are the inspirals of approximately
solar mass compact objects into massive black holes in the centres of galaxies
- extreme mass ratio inspirals (EMRIs). LISA should observe between a few tens
and a few hundred EMRIs over the mission lifetime, mostly at low redshifts (z <
1). Each observation will provide a measurement of the parameters of the host
system to unprecendented precision. LISA EMRI observations will thus offer a
new and unique way to probe black holes at low redshift. In this article we
provide a description of the population of EMRI events that LISA is likely to
observe, and describe how the numbers of events vary with changes in the
underlying assumptions about the black hole population. We also provide fitting
functions that characterise LISA's ability to detect EMRIs and which will allow
LISA event rates to be computed for arbitrary population models. We finish with
a discussion of an ongoing programme that will use these results to assess what
constraints LISA observations could place on galaxy evolution models.
| [
{
"created": "Sun, 2 Nov 2008 20:25:44 GMT",
"version": "v1"
},
{
"created": "Sun, 8 Mar 2009 23:03:39 GMT",
"version": "v2"
}
] | 2009-11-13 | [
[
"Gair",
"Jonathan R",
""
]
] | One of the most exciting potential sources of gravitational waves for the Laser Interferometer Space Antenna (LISA) are the inspirals of approximately solar mass compact objects into massive black holes in the centres of galaxies - extreme mass ratio inspirals (EMRIs). LISA should observe between a few tens and a few hundred EMRIs over the mission lifetime, mostly at low redshifts (z < 1). Each observation will provide a measurement of the parameters of the host system to unprecendented precision. LISA EMRI observations will thus offer a new and unique way to probe black holes at low redshift. In this article we provide a description of the population of EMRI events that LISA is likely to observe, and describe how the numbers of events vary with changes in the underlying assumptions about the black hole population. We also provide fitting functions that characterise LISA's ability to detect EMRIs and which will allow LISA event rates to be computed for arbitrary population models. We finish with a discussion of an ongoing programme that will use these results to assess what constraints LISA observations could place on galaxy evolution models. |
gr-qc/0605062 | Leonardo Augusto Pach\'on Contreras | Leonardo A. Pachon and Jorge A. Rueda | About Poynting vector in axially symmetric stationary spacetimes | Latex, 2 pages | null | null | null | gr-qc | null | We dispose of some objections raised by Manko et al. (gr-qc/0604091) on a
recently published paper on the role of Poynting vector in the ocurrence of
vorticity in electrovaccum spacetimes (2006, Class. Quantum Grav. 23, 2395)
| [
{
"created": "Wed, 10 May 2006 23:32:02 GMT",
"version": "v1"
},
{
"created": "Fri, 12 May 2006 15:56:50 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Pachon",
"Leonardo A.",
""
],
[
"Rueda",
"Jorge A.",
""
]
] | We dispose of some objections raised by Manko et al. (gr-qc/0604091) on a recently published paper on the role of Poynting vector in the ocurrence of vorticity in electrovaccum spacetimes (2006, Class. Quantum Grav. 23, 2395) |
1904.12861 | Matthijs van der Wild | Christian F. Steinwachs, Matthijs L. van der Wild | Quantum gravitational corrections to the inflationary power spectra in
scalar-tensor theories | 35 pages, 1 figure | null | 10.1088/1361-6382/ab3a1b | FR-Pheno-2019-006 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive the first quantum gravitational corrections to the inflationary
power spectra for a general single-field scalar-tensor theory which includes a
non-minimal coupling to gravity, a non-standard scalar kinetic term and an
arbitrary potential of the scalar field. We obtain these corrections from a
semiclassical expansion of the Wheeler-DeWitt equation, which, in turn, governs
the full quantum dynamics in the canonical approach to quantum gravity. We
discuss the magnitude and relevance of these corrections, as well as their
characteristic signature in the inflationary spectral observables. We compare
our results to similar calculations performed for a minimally coupled scalar
field with a canonical kinetic term and discuss the impact of the non-minimal
coupling on the quantum gravitational corrections.
| [
{
"created": "Mon, 29 Apr 2019 18:00:01 GMT",
"version": "v1"
}
] | 2020-01-08 | [
[
"Steinwachs",
"Christian F.",
""
],
[
"van der Wild",
"Matthijs L.",
""
]
] | We derive the first quantum gravitational corrections to the inflationary power spectra for a general single-field scalar-tensor theory which includes a non-minimal coupling to gravity, a non-standard scalar kinetic term and an arbitrary potential of the scalar field. We obtain these corrections from a semiclassical expansion of the Wheeler-DeWitt equation, which, in turn, governs the full quantum dynamics in the canonical approach to quantum gravity. We discuss the magnitude and relevance of these corrections, as well as their characteristic signature in the inflationary spectral observables. We compare our results to similar calculations performed for a minimally coupled scalar field with a canonical kinetic term and discuss the impact of the non-minimal coupling on the quantum gravitational corrections. |
gr-qc/0203094 | Marie-Noelle Celerier | Marie-Noelle Celerier (Observatoire de Paris-Meudon), Peter Szekeres
(University of Adelaide) | Timelike and null focusing singularities in spherical symmetry: a
solution to the cosmological horizon problem and a challenge to the cosmic
censorship hypothesis | 26 pages, 2 figures, LaTeX file. Submitted to Phys. Rev. D | Phys.Rev.D65:123516,2002 | 10.1103/PhysRevD.65.123516 | null | gr-qc | null | Extending the study of spherically symmetric metrics satisfying the dominant
energy condition and exhibiting singularities of power-law type initiated in
SI93, we identify two classes of peculiar interest: focusing timelike
singularity solutions with the stress-energy tensor of a radiative perfect
fluid (equation of state: $p={1\over 3} \rho$) and a set of null singularity
classes verifying identical properties. We consider two important applications
of these results: to cosmology, as regards the possibility of solving the
horizon problem with no need to resort to any inflationary scenario, and to the
Strong Cosmic Censorship Hypothesis to which we propose a class of physically
consistent counter-examples.
| [
{
"created": "Tue, 26 Mar 2002 16:16:26 GMT",
"version": "v1"
}
] | 2010-11-19 | [
[
"Celerier",
"Marie-Noelle",
"",
"Observatoire de Paris-Meudon"
],
[
"Szekeres",
"Peter",
"",
"University of Adelaide"
]
] | Extending the study of spherically symmetric metrics satisfying the dominant energy condition and exhibiting singularities of power-law type initiated in SI93, we identify two classes of peculiar interest: focusing timelike singularity solutions with the stress-energy tensor of a radiative perfect fluid (equation of state: $p={1\over 3} \rho$) and a set of null singularity classes verifying identical properties. We consider two important applications of these results: to cosmology, as regards the possibility of solving the horizon problem with no need to resort to any inflationary scenario, and to the Strong Cosmic Censorship Hypothesis to which we propose a class of physically consistent counter-examples. |
1003.3287 | Myungseok Eune | Wontae Kim, Young-Jai Park, Myungseok Yoon | Entropy of the FRW universe based on the generalized uncertainty
principle | 10 pages, accepted in Modern Physics Letters A | Mod.Phys.Lett.A25:1267-1274,2010 | 10.1142/S0217732310033049 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The statistical entropy of the FRW universe described by time-dependent
metric is newly calculated using the brick wall method based on the general
uncertainty principle with the minimal length. We can determine the minimal
length with the Plank scale to obtain the entropy proportional to the area of
the cosmological apparent horizon.
| [
{
"created": "Wed, 17 Mar 2010 03:25:49 GMT",
"version": "v1"
},
{
"created": "Mon, 2 Aug 2010 07:42:00 GMT",
"version": "v2"
}
] | 2014-11-20 | [
[
"Kim",
"Wontae",
""
],
[
"Park",
"Young-Jai",
""
],
[
"Yoon",
"Myungseok",
""
]
] | The statistical entropy of the FRW universe described by time-dependent metric is newly calculated using the brick wall method based on the general uncertainty principle with the minimal length. We can determine the minimal length with the Plank scale to obtain the entropy proportional to the area of the cosmological apparent horizon. |
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