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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1608.03186 | Hao Wen | Hao Wen, Fangyu Li, Jin Li, Zhenyun Fang, Andrew Beckwith | Very high frequency gravitational waves from magnetars and gamma-ray
burst | null | Chinese Physics C, Vol. 41, No. 12 (2017) 125101 | 10.1088/1674-1137/41/12/125101 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Extremely powerful astrophysical electromagnetic (EM) system could be
possible source of high-frequency gravitational waves (HFGWs). Here based on
properties of magnetars and gamma-ray bursts (GRBs), we address "Gamma-HFGWs"
(with very high-frequency around 10^{20}Hz) caused by ultra-strong EM
radiations (in the radiation-dominated phase of GRBs fireball) interacting with
super-high magnetar surface magnetic fields (around 10^{11}Tesla). By certain
parameters of distance and power, the Gamma-HFGWs would have far field energy
density around 10^{-6}, and they would cause perturbed signal EM waves of
around 10^{-20}Watt/m^2 in planned HFGW detection system based on EM response
to GWs. Specially, Gamma-HFGWs would possess distinctive envelopes with
characteristic shapes depending on the particular structures of surface
magnetic fields of magnetars, which could be exclusive features helpful to
distinguish them from background noise. Results obtained suggest that magnetars
could involve in possible astrophysical EM sources of GWs in very
high-frequency band, and Gamma-HFGWs would be potential targets for
observations in the future.
| [
{
"created": "Sun, 17 Jul 2016 21:48:48 GMT",
"version": "v1"
},
{
"created": "Wed, 26 Apr 2017 07:45:16 GMT",
"version": "v2"
},
{
"created": "Wed, 18 Oct 2017 19:54:22 GMT",
"version": "v3"
}
] | 2024-04-04 | [
[
"Wen",
"Hao",
""
],
[
"Li",
"Fangyu",
""
],
[
"Li",
"Jin",
""
],
[
"Fang",
"Zhenyun",
""
],
[
"Beckwith",
"Andrew",
""
]
] | Extremely powerful astrophysical electromagnetic (EM) system could be possible source of high-frequency gravitational waves (HFGWs). Here based on properties of magnetars and gamma-ray bursts (GRBs), we address "Gamma-HFGWs" (with very high-frequency around 10^{20}Hz) caused by ultra-strong EM radiations (in the radiation-dominated phase of GRBs fireball) interacting with super-high magnetar surface magnetic fields (around 10^{11}Tesla). By certain parameters of distance and power, the Gamma-HFGWs would have far field energy density around 10^{-6}, and they would cause perturbed signal EM waves of around 10^{-20}Watt/m^2 in planned HFGW detection system based on EM response to GWs. Specially, Gamma-HFGWs would possess distinctive envelopes with characteristic shapes depending on the particular structures of surface magnetic fields of magnetars, which could be exclusive features helpful to distinguish them from background noise. Results obtained suggest that magnetars could involve in possible astrophysical EM sources of GWs in very high-frequency band, and Gamma-HFGWs would be potential targets for observations in the future. |
1010.0099 | Arturo Stabile | A. Stabile, S. Capozziello | Weak Field Approach in f(R)-Gravity | 4 pages, 5 figures, Proceedings of SAIt 2010 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this communication we discuss the Weak Field Approach, and in particular
the Newtonian limit, applied to f(R)-Gravity. Particular emphasis is placed on
the spherically symmetric solutions and finally, it is clearly shown that
General Relativity results, in the Solar System context, are easily recovered
since Einstein theory is a particular case of $f(R)$-Gravity. This is a crucial
point against several wrong results in literature stating that these theories
are not viable at local scales.
| [
{
"created": "Fri, 1 Oct 2010 09:14:43 GMT",
"version": "v1"
}
] | 2010-10-04 | [
[
"Stabile",
"A.",
""
],
[
"Capozziello",
"S.",
""
]
] | In this communication we discuss the Weak Field Approach, and in particular the Newtonian limit, applied to f(R)-Gravity. Particular emphasis is placed on the spherically symmetric solutions and finally, it is clearly shown that General Relativity results, in the Solar System context, are easily recovered since Einstein theory is a particular case of $f(R)$-Gravity. This is a crucial point against several wrong results in literature stating that these theories are not viable at local scales. |
1206.3077 | Mandar Patil | Satyabrata Sahu, Mandar Patil, D. Narasimha, Pankaj S. Joshi | Can strong gravitational lensing distinguish naked singularities from
black holes? | 13 pages; 9 figures; 3 tables; modified discussion on the JNW
geometry; accepted for publication in Physical Review D | Phys. Rev. D 86, 063010 (2012) | 10.1103/PhysRevD.86.063010 | null | gr-qc astro-ph.GA hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we study gravitational lensing in the strong field limit from
the perspective of cosmic censorship, to investigate whether or not naked
singularities, if at all they exist in nature, can be distinguished from black
holes. We study the gravitational lensing in the strong field regime in the JMN
spacetime, a spherically symmetric geometry that contains a naked singularity
and which matches smoothly with Schwarzschild metric beyond a finite radius.
This metric is a toy model which was shown recently to be the end state of
gravitational collapse. In the presence of the photon sphere gravitational
lensing signature of this spacetime is identical to that of Schwarzschild black
hole with infinitely many relativistic images and Einstein rings, all of them
located beyond a certain critical angle from optic axis and the inner
relativistic images all clumped together. However, in the absence of the photon
sphere, which is the case for a wide range of parameter values in this
spacetime, we show that we get finitely many relativistic images and Einstein
rings spaced reasonably apart from one another, some of which can be formed
inside the critical angle for the corresponding Schwarzschild black hole. This
study suggests that the observation of relativistic images and rings might, in
principle, allow us to unravel the existence of the naked singularity in the
absence of the photon sphere. The results obtained here are in contrast with
the earlier investigation on JNW naked singularities radial caustic was always
present in the absence of photon sphere, while it is absent in JMN geometry. We
also point out the practical difficulties that might be encountered in the
observation of the relativistic images and suggest that new dedicated
experiments and techniques must be developed in future for this purpose.
| [
{
"created": "Thu, 14 Jun 2012 12:05:18 GMT",
"version": "v1"
},
{
"created": "Thu, 23 Aug 2012 17:31:12 GMT",
"version": "v2"
}
] | 2012-09-21 | [
[
"Sahu",
"Satyabrata",
""
],
[
"Patil",
"Mandar",
""
],
[
"Narasimha",
"D.",
""
],
[
"Joshi",
"Pankaj S.",
""
]
] | In this paper we study gravitational lensing in the strong field limit from the perspective of cosmic censorship, to investigate whether or not naked singularities, if at all they exist in nature, can be distinguished from black holes. We study the gravitational lensing in the strong field regime in the JMN spacetime, a spherically symmetric geometry that contains a naked singularity and which matches smoothly with Schwarzschild metric beyond a finite radius. This metric is a toy model which was shown recently to be the end state of gravitational collapse. In the presence of the photon sphere gravitational lensing signature of this spacetime is identical to that of Schwarzschild black hole with infinitely many relativistic images and Einstein rings, all of them located beyond a certain critical angle from optic axis and the inner relativistic images all clumped together. However, in the absence of the photon sphere, which is the case for a wide range of parameter values in this spacetime, we show that we get finitely many relativistic images and Einstein rings spaced reasonably apart from one another, some of which can be formed inside the critical angle for the corresponding Schwarzschild black hole. This study suggests that the observation of relativistic images and rings might, in principle, allow us to unravel the existence of the naked singularity in the absence of the photon sphere. The results obtained here are in contrast with the earlier investigation on JNW naked singularities radial caustic was always present in the absence of photon sphere, while it is absent in JMN geometry. We also point out the practical difficulties that might be encountered in the observation of the relativistic images and suggest that new dedicated experiments and techniques must be developed in future for this purpose. |
2002.08336 | Thomas Buchert | L\'eo Brunswic and Thomas Buchert | Gauss-Bonnet-Chern approach to the averaged Universe | 44 pages, matches published version in CQG | Class. Quantum Grav. 37 (2020) 215022 | 10.1088/1361-6382/abae45 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The standard model of cosmology with postulated dark energy and dark matter
sources may be considered as a fairly successful fitting model to observational
data. However, this model leaves the question of the physical origin of these
dark components open. Fully relativistic contributions that act like dark
energy on large scales and like dark matter on smaller scales can be found
through generalization of the standard model by spatially averaging the
inhomogeneous Universe within general relativity. The spatially averaged 3+1
Einstein equations are effective balance equations that need a closure
condition. Heading for closure we here explore topological constraints. Results
are straightforwardly obtained for averaged 2+1 model universes. For the
relevant 3+1 case, we employ a method based on the Gauss-Bonnet-Chern theorem
generalized to Lorentzian spacetimes and implement a sandwich approach to
obtain spatial average properties. The 3+1 topological approach supplies us
with a new equation linking evolution of scalar invariants of the expansion
tensor to the norm of the Weyl tensor. From this we derive general evolution
equations for averaged scalar curvature and kinematical backreaction, and we
discuss related evolution equations on this level of the hierarchy of averaged
equations. We also discuss the relation between topological properties of
cosmological manifolds and dynamical topology change, e.g. as resulting from
the formation of black holes.
| [
{
"created": "Wed, 19 Feb 2020 18:21:29 GMT",
"version": "v1"
},
{
"created": "Mon, 16 Mar 2020 20:38:39 GMT",
"version": "v2"
},
{
"created": "Thu, 22 Oct 2020 18:34:28 GMT",
"version": "v3"
}
] | 2020-10-26 | [
[
"Brunswic",
"Léo",
""
],
[
"Buchert",
"Thomas",
""
]
] | The standard model of cosmology with postulated dark energy and dark matter sources may be considered as a fairly successful fitting model to observational data. However, this model leaves the question of the physical origin of these dark components open. Fully relativistic contributions that act like dark energy on large scales and like dark matter on smaller scales can be found through generalization of the standard model by spatially averaging the inhomogeneous Universe within general relativity. The spatially averaged 3+1 Einstein equations are effective balance equations that need a closure condition. Heading for closure we here explore topological constraints. Results are straightforwardly obtained for averaged 2+1 model universes. For the relevant 3+1 case, we employ a method based on the Gauss-Bonnet-Chern theorem generalized to Lorentzian spacetimes and implement a sandwich approach to obtain spatial average properties. The 3+1 topological approach supplies us with a new equation linking evolution of scalar invariants of the expansion tensor to the norm of the Weyl tensor. From this we derive general evolution equations for averaged scalar curvature and kinematical backreaction, and we discuss related evolution equations on this level of the hierarchy of averaged equations. We also discuss the relation between topological properties of cosmological manifolds and dynamical topology change, e.g. as resulting from the formation of black holes. |
0803.2533 | Stanislav Hled\'ik | Zden\v{e}k Stuchl\'ik, Stanislav Hled\'ik and Josef Jur\'a\v{n} | Optical reference geometry of the Kerr-Newman spacetimes | 28 pages, 17 figures | Class.Quant.Grav.17:2691-2718,2000 | 10.1088/0264-9381/17/14/307 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Properties of the optical reference geometry related to Kerr-Newman
black-hole and naked-singularity spacetimes are illustrated using embedding
diagrams of their equatorial plane. Among all inertial forces defined in the
framework of the optical geometry, just the centrifugal force plays a
fundamental role in connection to the embedding diagrams because it changes
sign at the turning points of the diagrams. The limits of embeddability are
given, and it is established which of the photon circular orbits hosted the by
Kerr-Newman spacetimes appear in the embeddable regions. Some typical embedding
diagrams are constructed, and the Kerr-Newman backgrounds are classified
according to the number of embeddable regions of the optical geometry as well
as the number of their turning points. Embedding diagrams are closely related
to the notion of the radius of gyration which is useful for analyzing fluid
rotating in strong gravitational fields.
| [
{
"created": "Mon, 17 Mar 2008 21:35:33 GMT",
"version": "v1"
}
] | 2009-11-13 | [
[
"Stuchlík",
"Zdeněk",
""
],
[
"Hledík",
"Stanislav",
""
],
[
"Juráň",
"Josef",
""
]
] | Properties of the optical reference geometry related to Kerr-Newman black-hole and naked-singularity spacetimes are illustrated using embedding diagrams of their equatorial plane. Among all inertial forces defined in the framework of the optical geometry, just the centrifugal force plays a fundamental role in connection to the embedding diagrams because it changes sign at the turning points of the diagrams. The limits of embeddability are given, and it is established which of the photon circular orbits hosted the by Kerr-Newman spacetimes appear in the embeddable regions. Some typical embedding diagrams are constructed, and the Kerr-Newman backgrounds are classified according to the number of embeddable regions of the optical geometry as well as the number of their turning points. Embedding diagrams are closely related to the notion of the radius of gyration which is useful for analyzing fluid rotating in strong gravitational fields. |
1106.5575 | Claudio Dappiaggi | Claudio Dappiaggi and Daniel Siemssen | Hadamard States for the Vector Potential on Asymptotically Flat
Spacetimes | 25 pages, comments added, improved notation, minor typos corrected
and updated bibliography | Rev.Math.Phys.25:1350002,2013 | null | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We develop a quantization scheme for the vector potential on globally
hyperbolic spacetimes which realizes it as a locally covariant conformal
quantum field theory. This result allows us to employ on a large class of
backgrounds, which are asymptotically flat at null infinity, a bulk-to-boundary
correspondence procedure in order to identify for the underlying field algebra
a distinguished ground state which is of Hadamard form.
| [
{
"created": "Tue, 28 Jun 2011 06:51:32 GMT",
"version": "v1"
},
{
"created": "Mon, 11 Jul 2011 15:40:25 GMT",
"version": "v2"
},
{
"created": "Fri, 22 Jul 2011 17:13:49 GMT",
"version": "v3"
},
{
"created": "Sat, 16 Feb 2013 17:31:31 GMT",
"version": "v4"
}
] | 2013-02-19 | [
[
"Dappiaggi",
"Claudio",
""
],
[
"Siemssen",
"Daniel",
""
]
] | We develop a quantization scheme for the vector potential on globally hyperbolic spacetimes which realizes it as a locally covariant conformal quantum field theory. This result allows us to employ on a large class of backgrounds, which are asymptotically flat at null infinity, a bulk-to-boundary correspondence procedure in order to identify for the underlying field algebra a distinguished ground state which is of Hadamard form. |
2111.05556 | Felix Finster | Felix Finster, Maximilian Jokel, Claudio F. Paganini | A Mechanism of Baryogenesis for Causal Fermion Systems | 50 pages, LaTeX, 7 figures, correction in formula (5.10) | Class. Quantum Grav. 39 (2022) 165005 | 10.1088/1361-6382/ac7a86 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is shown that the theory of causal fermion systems gives rise to a novel
mechanism of baryogenesis. This mechanism is worked out computationally in
globally hyperbolic spacetimes in a way which enables the quantitative study in
concrete cosmological situations.
| [
{
"created": "Wed, 10 Nov 2021 07:40:04 GMT",
"version": "v1"
},
{
"created": "Thu, 30 Jun 2022 05:59:00 GMT",
"version": "v2"
},
{
"created": "Mon, 11 Sep 2023 07:29:32 GMT",
"version": "v3"
}
] | 2023-09-12 | [
[
"Finster",
"Felix",
""
],
[
"Jokel",
"Maximilian",
""
],
[
"Paganini",
"Claudio F.",
""
]
] | It is shown that the theory of causal fermion systems gives rise to a novel mechanism of baryogenesis. This mechanism is worked out computationally in globally hyperbolic spacetimes in a way which enables the quantitative study in concrete cosmological situations. |
1106.1426 | Wade Naylor | H. T. Cho (Tamkang U.), A. S. Cornell (Witwatersrand U.), Jason Doukas
(Kyoto U., Yukawa Inst., Kyoto) and Wade Naylor (Osaka U.) | Scalar spheroidal harmonics in five dimensional Kerr-(A)dS | 11 pages, two figures, one table; vz. 2: reference added and grammar
corrected | Prog. Theor. Phys. 128 (2012), 227-241 | 10.1143/PTP.128.227 | YITP-11-63, WITS-CTP-74, OU-HET-708/2011 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive expressions for the general five-dimensional metric for Kerr-(A)dS
black holes. The Klein-Gordon equation is explicitly separated and we show that
the angular part of the wave equation leads to just one spheroidal wave
equation, which is also that for charged five-dimensional Kerr-(A)dS black
holes. We present results for the perturbative expansion of the angular
eigenvalue in powers of the rotation parameters up to 6th order and compare
numerically with the continued fraction method.
| [
{
"created": "Tue, 7 Jun 2011 19:59:45 GMT",
"version": "v1"
},
{
"created": "Thu, 23 Jun 2011 05:17:59 GMT",
"version": "v2"
}
] | 2012-09-03 | [
[
"Cho",
"H. T.",
"",
"Tamkang U."
],
[
"Cornell",
"A. S.",
"",
"Witwatersrand U."
],
[
"Doukas",
"Jason",
"",
"Kyoto U., Yukawa Inst., Kyoto"
],
[
"Naylor",
"Wade",
"",
"Osaka U."
]
] | We derive expressions for the general five-dimensional metric for Kerr-(A)dS black holes. The Klein-Gordon equation is explicitly separated and we show that the angular part of the wave equation leads to just one spheroidal wave equation, which is also that for charged five-dimensional Kerr-(A)dS black holes. We present results for the perturbative expansion of the angular eigenvalue in powers of the rotation parameters up to 6th order and compare numerically with the continued fraction method. |
gr-qc/9405012 | Pavol Kolnik | C. Klimcik, P. Kolnik, and A. Pompos | Non-commutative black holes in $D$ dimensions | 15 pp., LaTeX, preprint PRA-HEP-94/5 | null | null | null | gr-qc | null | Recently introduced classical theory of gravity in non-commutative geometry
is studied. The most general (four parametric) family of $D$ dibensional static
spherically symmetric spacetimes is identified and its properties are studied
in detail. For wide class of the choices of parameters, the corresponding
spacetimes have the structure of asymptotically flat black holes with a smooth
event horizon hiding the curvature singularity. A specific attention is devoted
to the behavior of components of the metric in non-commutative direction, which
are interpreted as the black hole hair.
| [
{
"created": "Fri, 6 May 1994 10:10:20 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Klimcik",
"C.",
""
],
[
"Kolnik",
"P.",
""
],
[
"Pompos",
"A.",
""
]
] | Recently introduced classical theory of gravity in non-commutative geometry is studied. The most general (four parametric) family of $D$ dibensional static spherically symmetric spacetimes is identified and its properties are studied in detail. For wide class of the choices of parameters, the corresponding spacetimes have the structure of asymptotically flat black holes with a smooth event horizon hiding the curvature singularity. A specific attention is devoted to the behavior of components of the metric in non-commutative direction, which are interpreted as the black hole hair. |
1508.02337 | Aghil Alaee | Aghil Alaee and Hari K. Kunduri | Remarks on mass and angular momenta for $U(1)^2$-invariant initial data | 17 pages, LaTeX; v2. assumptions on generalized Brill data weakened
and the main theorem modified accordingly | null | 10.1063/1.4944426 | null | gr-qc math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We extend Brill's positive mass theorem to a large class of asymptotically
flat, maximal, $U(1)^2$-invariant initial data sets on simply connected four
dimensional manifolds $\Sigma$. Moreover, we extend the local mass angular
momenta inequality result Ref [1] for $U(1)^2$ invariant black holes to the
case with nonzero stress energy tensor with positive matter density and
energy-momentum current invariant under the above symmetries.
| [
{
"created": "Mon, 10 Aug 2015 18:02:23 GMT",
"version": "v1"
},
{
"created": "Sun, 6 Dec 2015 18:40:43 GMT",
"version": "v2"
}
] | 2016-04-20 | [
[
"Alaee",
"Aghil",
""
],
[
"Kunduri",
"Hari K.",
""
]
] | We extend Brill's positive mass theorem to a large class of asymptotically flat, maximal, $U(1)^2$-invariant initial data sets on simply connected four dimensional manifolds $\Sigma$. Moreover, we extend the local mass angular momenta inequality result Ref [1] for $U(1)^2$ invariant black holes to the case with nonzero stress energy tensor with positive matter density and energy-momentum current invariant under the above symmetries. |
1105.5812 | Victor Shchigolev Konstantinovich | V.K. Shchigolev, G.N. Orekhova | Non-Minimal Cosmological Model in Modified Yang--Mills Theory | 7 pages | Modern Physics Letters A (2011) Vol. 26, No. 26, pp. 1965-1973 | 10.1142/S0217732311036462 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the present paper, we consider a model of non-minimal modified Yang-Mills
theory in the Friedmann-Robertson-Walker cosmology, in which the Yang-Mills
field couples to the scalar curvature through a function of its first
invariant. We show that cosmic acceleration can be realized due to non-minimal
gravitational coupling of the modified Yang-Mills theory. Besides general
study, we consider in detail the case of power-law coupling function. We derive
the basic equations for the cosmic scale factor in our model, and provide
several examples of their solutions.
| [
{
"created": "Sun, 29 May 2011 18:43:15 GMT",
"version": "v1"
}
] | 2012-09-13 | [
[
"Shchigolev",
"V. K.",
""
],
[
"Orekhova",
"G. N.",
""
]
] | In the present paper, we consider a model of non-minimal modified Yang-Mills theory in the Friedmann-Robertson-Walker cosmology, in which the Yang-Mills field couples to the scalar curvature through a function of its first invariant. We show that cosmic acceleration can be realized due to non-minimal gravitational coupling of the modified Yang-Mills theory. Besides general study, we consider in detail the case of power-law coupling function. We derive the basic equations for the cosmic scale factor in our model, and provide several examples of their solutions. |
2207.08488 | Szymon Sikora | Szymon Sikora | Second-order dust perturbations of the non-flat FLRW model with the
positive cosmological constant | null | null | 10.1088/1361-6382/acaa81 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | In this paper, a specific solution to the second-order cosmological
perturbation theory is given. Perturbations are performed around any FLRW
spacetime filled with dust and with a positive cosmological constant. In
particular, with a possibly non-vanishing spatial curvature. The adopted
symmetry condition allows us to simplify the equations, leaving us with a great
deal of freedom to choose the density distribution. In the result, we get a
relatively simple metric of an inhomogeneous cosmological model, which will
give a perfect tool for studying the influence of the local inhomogeneities
onto the cosmological observables.
| [
{
"created": "Mon, 18 Jul 2022 10:12:51 GMT",
"version": "v1"
}
] | 2023-01-04 | [
[
"Sikora",
"Szymon",
""
]
] | In this paper, a specific solution to the second-order cosmological perturbation theory is given. Perturbations are performed around any FLRW spacetime filled with dust and with a positive cosmological constant. In particular, with a possibly non-vanishing spatial curvature. The adopted symmetry condition allows us to simplify the equations, leaving us with a great deal of freedom to choose the density distribution. In the result, we get a relatively simple metric of an inhomogeneous cosmological model, which will give a perfect tool for studying the influence of the local inhomogeneities onto the cosmological observables. |
gr-qc/0602054 | Wolfgang Graf | Wolfgang Graf | Ricci Flow Gravity | 15 pages. V2: improved presentation, in particular Jordan vs.
Brans-Dicke and on viability. Added section on physical interpretation. V3:
more references. Reworked to agree with published version | PMCPhys.A1:3,2007 | 10.1186/1754-0410-1-3 | null | gr-qc astro-ph hep-th math.DG | null | A theory of gravitation is proposed, modeled after the notion of a Ricci
flow. In addition to the metric an independent volume enters as a fundamental
geometric structure. Einstein gravity is included as a limiting case. Despite
being a scalar-tensor theory the coupling to matter is different from
Jordan-Brans-Dicke gravity. In particular there is no adjustable coupling
constant. For the solar system the effects of Ricci flow gravity cannot be
distinguished from Einstein gravity and therefore it passes all classical
tests. However for cosmology significant deviations from standard Einstein
cosmology will appear.
| [
{
"created": "Tue, 14 Feb 2006 20:22:50 GMT",
"version": "v1"
},
{
"created": "Wed, 1 Mar 2006 22:06:20 GMT",
"version": "v2"
},
{
"created": "Tue, 23 Oct 2007 18:51:09 GMT",
"version": "v3"
}
] | 2008-11-26 | [
[
"Graf",
"Wolfgang",
""
]
] | A theory of gravitation is proposed, modeled after the notion of a Ricci flow. In addition to the metric an independent volume enters as a fundamental geometric structure. Einstein gravity is included as a limiting case. Despite being a scalar-tensor theory the coupling to matter is different from Jordan-Brans-Dicke gravity. In particular there is no adjustable coupling constant. For the solar system the effects of Ricci flow gravity cannot be distinguished from Einstein gravity and therefore it passes all classical tests. However for cosmology significant deviations from standard Einstein cosmology will appear. |
1612.04177 | Kirill Bronnikov | S.V. Bolokhov, K.A. Bronnikov | Cosmology in nonlinear multidimensional gravity and the Casimir effect | 6 pages, 1 figure, submitted to Proceedings of the International
conference on particle physics and astrophysics (10-14 October 2016, Moscow,
Russia) | J. Phys. Conf. Series 798, 012091 (2017) | 10.1134/S0202289316040034 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the possible cosmological models in Kaluza-Klein-type
multidimensional gravity with a curvature-nonlinear Lagrangian and a spherical
extra space, taking into account the Casimir energy. First, we find a minimum
of the effective potential of extra dimensions, leading to a physically
reasonable value of the effective cosmological constant in our 4D space-time.
In this model, the huge Casimir energy density is compensated by a fine-tuned
contribution of the curvature-nonlinear terms in the original action. Second,
we present a viable model with slowly evolving extra dimensions and power-law
inflation in our space-time. In both models, the results formulated in Einstein
and Jordan frames are compared.
| [
{
"created": "Tue, 13 Dec 2016 13:57:37 GMT",
"version": "v1"
}
] | 2017-09-19 | [
[
"Bolokhov",
"S. V.",
""
],
[
"Bronnikov",
"K. A.",
""
]
] | We study the possible cosmological models in Kaluza-Klein-type multidimensional gravity with a curvature-nonlinear Lagrangian and a spherical extra space, taking into account the Casimir energy. First, we find a minimum of the effective potential of extra dimensions, leading to a physically reasonable value of the effective cosmological constant in our 4D space-time. In this model, the huge Casimir energy density is compensated by a fine-tuned contribution of the curvature-nonlinear terms in the original action. Second, we present a viable model with slowly evolving extra dimensions and power-law inflation in our space-time. In both models, the results formulated in Einstein and Jordan frames are compared. |
1809.05355 | Joao Magueijo | John D. Barrow and Joao Magueijo | Do we live in an eigenstate of the "fundamental constants" operators? | Accepted manuscript | Phys. Rev. D 99, 023509 (2019) | 10.1103/PhysRevD.99.023509 | null | gr-qc astro-ph.CO hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose that the constants of Nature we observe (which appear as
parameters in the classical action) are quantum observables in a kinematical
Hilbert space. When all of these observables commute, our proposal differs
little from the treatment given to classical parameters in quantum information
theory, at least if we were to inhabit a constants' eigenstate.
Non-commutativity introduces novelties, due to its associated uncertainty and
complementarity principles, and it may even preclude hamiltonian evolution. The
system typically evolves as a quantum superposition of hamiltonian evolutions
resulting from a diagonalization process, and these are usually quite distinct
from the original one (defined in terms of the non-commuting constants). We
present several examples targeting $G$, $c$ and $\Lambda $, and the dynamics of
homogeneous and isotropic Universes. If we base our construction on the
Heisenberg algebra and the quantum harmonic oscillator, the alternative
dynamics tends to silence matter (effectively setting $G$ to zero), and make
curvature and the cosmological constant act as if their signs are reversed.
Thus, the early Universe expands as a quantum superposition of different Milne
or de Sitter expansions for all material equations of state, even though matter
nominally dominates the density, $\rho $, because of the negligible influence
of $G\rho $ on the dynamics. A superposition of Einstein static universes can
also be obtained. We also investigate the results of basing our construction on
the algebra of $SU(2)$, into which we insert information about the sign of a
constant of Nature, or whether its action is switched on or off. In this case
we find examples displaying quantum superpositions of bounces at the initial
state for the Universe.
| [
{
"created": "Fri, 14 Sep 2018 11:10:31 GMT",
"version": "v1"
},
{
"created": "Thu, 20 Dec 2018 11:05:13 GMT",
"version": "v2"
}
] | 2019-01-09 | [
[
"Barrow",
"John D.",
""
],
[
"Magueijo",
"Joao",
""
]
] | We propose that the constants of Nature we observe (which appear as parameters in the classical action) are quantum observables in a kinematical Hilbert space. When all of these observables commute, our proposal differs little from the treatment given to classical parameters in quantum information theory, at least if we were to inhabit a constants' eigenstate. Non-commutativity introduces novelties, due to its associated uncertainty and complementarity principles, and it may even preclude hamiltonian evolution. The system typically evolves as a quantum superposition of hamiltonian evolutions resulting from a diagonalization process, and these are usually quite distinct from the original one (defined in terms of the non-commuting constants). We present several examples targeting $G$, $c$ and $\Lambda $, and the dynamics of homogeneous and isotropic Universes. If we base our construction on the Heisenberg algebra and the quantum harmonic oscillator, the alternative dynamics tends to silence matter (effectively setting $G$ to zero), and make curvature and the cosmological constant act as if their signs are reversed. Thus, the early Universe expands as a quantum superposition of different Milne or de Sitter expansions for all material equations of state, even though matter nominally dominates the density, $\rho $, because of the negligible influence of $G\rho $ on the dynamics. A superposition of Einstein static universes can also be obtained. We also investigate the results of basing our construction on the algebra of $SU(2)$, into which we insert information about the sign of a constant of Nature, or whether its action is switched on or off. In this case we find examples displaying quantum superpositions of bounces at the initial state for the Universe. |
1112.1961 | Sergei Alexandrov | Sergei Alexandrov, Marc Geiller, Karim Noui | Spin Foams and Canonical Quantization | null | SIGMA 8 (2012), 055, 79 pages | 10.3842/SIGMA.2012.055 | null | gr-qc hep-th | http://creativecommons.org/licenses/by-nc-sa/3.0/ | This review is devoted to the analysis of the mutual consistency of the spin
foam and canonical loop quantizations in three and four spacetime dimensions.
In the three-dimensional context, where the two approaches are in good
agreement, we show how the canonical quantization \`a la Witten of Riemannian
gravity with a positive cosmological constant is related to the Turaev-Viro
spin foam model, and how the Ponzano-Regge amplitudes are related to the
physical scalar product of Riemannian loop quantum gravity without cosmological
constant. In the four-dimensional case, we recall a Lorentz-covariant
formulation of loop quantum gravity using projected spin networks, compare it
with the new spin foam models, and identify interesting relations and their
pitfalls. Finally, we discuss the properties which a spin foam model is
expected to possess in order to be consistent with the canonical quantization,
and suggest a new model illustrating these results.
| [
{
"created": "Thu, 8 Dec 2011 21:09:08 GMT",
"version": "v1"
},
{
"created": "Mon, 26 Dec 2011 20:46:18 GMT",
"version": "v2"
},
{
"created": "Sun, 19 Aug 2012 05:16:34 GMT",
"version": "v3"
}
] | 2012-08-21 | [
[
"Alexandrov",
"Sergei",
""
],
[
"Geiller",
"Marc",
""
],
[
"Noui",
"Karim",
""
]
] | This review is devoted to the analysis of the mutual consistency of the spin foam and canonical loop quantizations in three and four spacetime dimensions. In the three-dimensional context, where the two approaches are in good agreement, we show how the canonical quantization \`a la Witten of Riemannian gravity with a positive cosmological constant is related to the Turaev-Viro spin foam model, and how the Ponzano-Regge amplitudes are related to the physical scalar product of Riemannian loop quantum gravity without cosmological constant. In the four-dimensional case, we recall a Lorentz-covariant formulation of loop quantum gravity using projected spin networks, compare it with the new spin foam models, and identify interesting relations and their pitfalls. Finally, we discuss the properties which a spin foam model is expected to possess in order to be consistent with the canonical quantization, and suggest a new model illustrating these results. |
2005.11697 | F Shojai | H. Khodabakhshi, A. Shirzad, F. Shojai, Robert B. Mann | Black Hole Entropy and Boundary Conditions | 22 pages, To appear in Phys. Rev. D | Phys. Rev. D 101, 124007 (2020) | 10.1103/PhysRevD.101.124007 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is well-known that in order to make the action well defined, one may
employ different kinds of boundary conditions (BCs) accompanied by the
appropriate Gibbons-Hawking-York (GHY) terms. In this paper we investigate the
role of the selected BC and the corresponding GHY terms on the black hole (BH)
entropy. Our result shows, regardless of the kind of BC, the BH entropy in all
cases is the same as one obtained under Dirichlet BC from Wald formula or
semi-classical approximation method. We considered the Schwarzschild solution
for $f(R)$-gravity and general relativity (GR) in standard dimensions as
special models.
| [
{
"created": "Sun, 24 May 2020 09:24:39 GMT",
"version": "v1"
}
] | 2020-07-01 | [
[
"Khodabakhshi",
"H.",
""
],
[
"Shirzad",
"A.",
""
],
[
"Shojai",
"F.",
""
],
[
"Mann",
"Robert B.",
""
]
] | It is well-known that in order to make the action well defined, one may employ different kinds of boundary conditions (BCs) accompanied by the appropriate Gibbons-Hawking-York (GHY) terms. In this paper we investigate the role of the selected BC and the corresponding GHY terms on the black hole (BH) entropy. Our result shows, regardless of the kind of BC, the BH entropy in all cases is the same as one obtained under Dirichlet BC from Wald formula or semi-classical approximation method. We considered the Schwarzschild solution for $f(R)$-gravity and general relativity (GR) in standard dimensions as special models. |
2311.05774 | Lucas Acito | Lucas Acito, Nicol\'as E. Grandi and Pablo Pisani | Superradiant black hole rocket | 35 pages, 27 figures | Phys. Rev. D 109, 065008 (2024) | 10.1103/PhysRevD.109.065008 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We calculate the total thrust resulting from the interaction between charged
scalar modes and a superradiant Reissner-Nordstr\"om black hole, when the modes
are deflected by a hemispherical perfect mirror located at a finite distance
from the black hole's horizon.
| [
{
"created": "Thu, 9 Nov 2023 22:32:06 GMT",
"version": "v1"
},
{
"created": "Fri, 17 Nov 2023 17:12:16 GMT",
"version": "v2"
},
{
"created": "Tue, 12 Mar 2024 16:42:03 GMT",
"version": "v3"
},
{
"created": "Thu, 21 Mar 2024 17:17:03 GMT",
"version": "v4"
}
] | 2024-03-22 | [
[
"Acito",
"Lucas",
""
],
[
"Grandi",
"Nicolás E.",
""
],
[
"Pisani",
"Pablo",
""
]
] | We calculate the total thrust resulting from the interaction between charged scalar modes and a superradiant Reissner-Nordstr\"om black hole, when the modes are deflected by a hemispherical perfect mirror located at a finite distance from the black hole's horizon. |
1908.11720 | Tanwi Bandyopadhyay | Tanwi Bandyopadhyay and Ujjal Debnath | Bouncing Cosmology for Entropy Corrected Models in Horava-Lifshitz
Gravity and Fractal Universe | 24 pages, 16 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The modified field equations are written in logarithmic and power law
versions of entropy corrected models in Einstein's gravity in the background of
FRW universe. In one section, a brief review of the Ho$\check{\text
r}$ava-Lifshitz gravity is discussed and the modified field equations in
logarithmic and power law versions of entropy corrected models in
Ho$\check{\text r}$ava-Lifshitz gravity are formulated. The stability analysis
for these models are performed by describing the dynamical system. In another
section, a brief review of the fractal universe is presented and the modified
field equations in logarithmic and power law versions of entropy corrected
models in fractal universe are formulated. The stability analysis for the
dynamical system for these models in the framework of fractal universe are
described. Furthermore, the bouncing scenarios of the universe in
Ho$\check{\text r}$ava-Lifshitz gravity and fractal model for both logarithmic
and power law entropy corrected versions in $k=0,+1,-1$ separately are
analyzed. For different cases, the validity of null energy condition (NEC) at
the time of bounce is examined. Finally, the behaviors of the physical
quantities are depicted through diagrams.
| [
{
"created": "Thu, 29 Aug 2019 11:32:26 GMT",
"version": "v1"
}
] | 2019-09-02 | [
[
"Bandyopadhyay",
"Tanwi",
""
],
[
"Debnath",
"Ujjal",
""
]
] | The modified field equations are written in logarithmic and power law versions of entropy corrected models in Einstein's gravity in the background of FRW universe. In one section, a brief review of the Ho$\check{\text r}$ava-Lifshitz gravity is discussed and the modified field equations in logarithmic and power law versions of entropy corrected models in Ho$\check{\text r}$ava-Lifshitz gravity are formulated. The stability analysis for these models are performed by describing the dynamical system. In another section, a brief review of the fractal universe is presented and the modified field equations in logarithmic and power law versions of entropy corrected models in fractal universe are formulated. The stability analysis for the dynamical system for these models in the framework of fractal universe are described. Furthermore, the bouncing scenarios of the universe in Ho$\check{\text r}$ava-Lifshitz gravity and fractal model for both logarithmic and power law entropy corrected versions in $k=0,+1,-1$ separately are analyzed. For different cases, the validity of null energy condition (NEC) at the time of bounce is examined. Finally, the behaviors of the physical quantities are depicted through diagrams. |
1512.04332 | Przemyslaw Malkiewicz | Przemyslaw Malkiewicz | Physical Hilbert Spaces in Quantum Gravity | 6 pages, Proceedings of the 14th Marcel Grossmann Meeting (Rome, July
12-18, 2015) | null | null | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We summarize our investigation of the extent to which the choice of internal
clock influences the dynamics in quantum models of gravity. Firstly, at the
classical level, we define an extension to the Hamilton-Jacobi theory of
contact transformations, which allows for transformations of time coordinates.
Secondly, at the quantum level, we employ the extended theory to separate the
quantum effects brought by the free choice of internal clock from those
originating from inequivalent quantization maps. Next, we show with two
examples two kinds of origin of the clock effect in quantum gravitational
systems.
| [
{
"created": "Mon, 14 Dec 2015 14:19:49 GMT",
"version": "v1"
}
] | 2015-12-15 | [
[
"Malkiewicz",
"Przemyslaw",
""
]
] | We summarize our investigation of the extent to which the choice of internal clock influences the dynamics in quantum models of gravity. Firstly, at the classical level, we define an extension to the Hamilton-Jacobi theory of contact transformations, which allows for transformations of time coordinates. Secondly, at the quantum level, we employ the extended theory to separate the quantum effects brought by the free choice of internal clock from those originating from inequivalent quantization maps. Next, we show with two examples two kinds of origin of the clock effect in quantum gravitational systems. |
1806.08617 | Sam Dolan Dr | Sam R Dolan | Geometrical optics for scalar, electromagnetic and gravitational waves
in curved spacetime | 17 pages, 1 figure. Proceedings for IV Amazonian Symposium on
Physics, Belem, Brazil at UFPA on 18-22 Sep 2017 | Int. J. Mod. Phys. D 1843010 (2018) | 10.1142/S0218271818430101 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The geometrical-optics expansion reduces the problem of solving wave
equations to one of solving transport equations along rays. Here we consider
scalar, electromagnetic and gravitational waves propagating on a curved
spacetime in general relativity. We show that each is governed by a wave
equation with the same principal part. It follows that: each wave propagates at
the speed of light along rays (null generators of hypersurfaces of constant
phase); the square of the wave amplitude varies in inverse proportion to the
cross section of the beam; and the polarization is parallel-propagated along
the ray (the Skrotskii/Rytov effect). We show that the optical scalars for a
beam, and various Newman-Penrose scalars describing a parallel-propagated null
tetrad, can be found by solving transport equations in a second-order
formulation. Unlike the Sachs equations, this formulation makes it
straightforward to find such scalars beyond the first conjugate point of a
congruence, where neighbouring rays cross, and the scalars diverge. We discuss
differential precession across the beam which leads to a modified phase in the
geometrical-optics expansion.
| [
{
"created": "Fri, 22 Jun 2018 12:02:38 GMT",
"version": "v1"
}
] | 2018-06-25 | [
[
"Dolan",
"Sam R",
""
]
] | The geometrical-optics expansion reduces the problem of solving wave equations to one of solving transport equations along rays. Here we consider scalar, electromagnetic and gravitational waves propagating on a curved spacetime in general relativity. We show that each is governed by a wave equation with the same principal part. It follows that: each wave propagates at the speed of light along rays (null generators of hypersurfaces of constant phase); the square of the wave amplitude varies in inverse proportion to the cross section of the beam; and the polarization is parallel-propagated along the ray (the Skrotskii/Rytov effect). We show that the optical scalars for a beam, and various Newman-Penrose scalars describing a parallel-propagated null tetrad, can be found by solving transport equations in a second-order formulation. Unlike the Sachs equations, this formulation makes it straightforward to find such scalars beyond the first conjugate point of a congruence, where neighbouring rays cross, and the scalars diverge. We discuss differential precession across the beam which leads to a modified phase in the geometrical-optics expansion. |
1402.4138 | Marc Geiller | Marc Geiller, Karim Noui | Near-Horizon Radiation and Self-Dual Loop Quantum Gravity | 6+2 pages | Europhys. Lett. 105 (2014) 60001 | 10.1209/0295-5075/105/60001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compute the near-horizon radiation of quantum black holes in the context
of self-dual loop quantum gravity. For this, we first use the unitary spinor
basis of $\text{SL}(2,\mathbb{C})$ to decompose states of Lorentzian spin foam
models into their self-dual and anti self-dual parts, and show that the reduced
density matrix obtained by tracing over one chiral component describes a
thermal state at Unruh temperature. Then, we show that the
analytically-continued dimension of the $\text{SU}(2)$ Chern-Simons Hilbert
space, which reproduces the Bekenstein-Hawking entropy in the large spin limit
in agreement with the large spin effective action, takes the form of a
partition function for states thermalized at Unruh temperature, with discrete
energy levels given by the near-horizon energy of Frodden-Gosh-Perez, and with
a degenerate ground state which is holographic and responsible for the entropy.
| [
{
"created": "Mon, 17 Feb 2014 21:00:34 GMT",
"version": "v1"
}
] | 2014-03-27 | [
[
"Geiller",
"Marc",
""
],
[
"Noui",
"Karim",
""
]
] | We compute the near-horizon radiation of quantum black holes in the context of self-dual loop quantum gravity. For this, we first use the unitary spinor basis of $\text{SL}(2,\mathbb{C})$ to decompose states of Lorentzian spin foam models into their self-dual and anti self-dual parts, and show that the reduced density matrix obtained by tracing over one chiral component describes a thermal state at Unruh temperature. Then, we show that the analytically-continued dimension of the $\text{SU}(2)$ Chern-Simons Hilbert space, which reproduces the Bekenstein-Hawking entropy in the large spin limit in agreement with the large spin effective action, takes the form of a partition function for states thermalized at Unruh temperature, with discrete energy levels given by the near-horizon energy of Frodden-Gosh-Perez, and with a degenerate ground state which is holographic and responsible for the entropy. |
2003.11554 | Manuel Hohmann | Sebastian Bahamonde, Konstantinos F. Dialektopoulos, Manuel Hohmann,
Jackson Levi Said | Post-Newtonian limit of Teleparallel Horndeski gravity | LaTeX, 22 pages, no figures; version accepted by Classical and
Quantum Gravity | null | 10.1088/1361-6382/abc441 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the newly proposed Bahamonde-Dialektopoulos-Levi Said (BDLS)
theory, that is the Horndeski analog in the teleparallel framework and thus
contains a non-minimally coupled scalar field, including higher order
derivatives, that leads however to second order field equations both for the
tetrad and the scalar field. This theory was mostly constructed to revive those
models that were severely constrained in the scalar-tensor version of the
theory from the GW170817, but includes also much richer phenomenology because
of the nature of the torsion tensor. For this theory we determine the
parametrized post-Newtonian limit, calculate the full set of post-Newtonian
parameters and highlight some special cases.
| [
{
"created": "Wed, 25 Mar 2020 18:00:03 GMT",
"version": "v1"
},
{
"created": "Tue, 3 Nov 2020 11:54:31 GMT",
"version": "v2"
}
] | 2020-11-04 | [
[
"Bahamonde",
"Sebastian",
""
],
[
"Dialektopoulos",
"Konstantinos F.",
""
],
[
"Hohmann",
"Manuel",
""
],
[
"Said",
"Jackson Levi",
""
]
] | We consider the newly proposed Bahamonde-Dialektopoulos-Levi Said (BDLS) theory, that is the Horndeski analog in the teleparallel framework and thus contains a non-minimally coupled scalar field, including higher order derivatives, that leads however to second order field equations both for the tetrad and the scalar field. This theory was mostly constructed to revive those models that were severely constrained in the scalar-tensor version of the theory from the GW170817, but includes also much richer phenomenology because of the nature of the torsion tensor. For this theory we determine the parametrized post-Newtonian limit, calculate the full set of post-Newtonian parameters and highlight some special cases. |
2408.02116 | Thomas Law | Aviral Damle and Thomas Law | A speculative model for cyclic information preservation in Kerr-Newman
spacetime using closed timelike curves | null | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | This paper presents a speculative model exploring the behavior of quantum
information for particles entering closed timelike curves (CTCs) in Kerr-Newman
spacetime. We apply Gavassino's restoration principle to derive a theoretical
framework for cyclic information dynamics within these extreme gravitational
environments. Our model focuses specifically on particles that enter CTCs near
the inner horizon of a Kerr-Newman black hole, examining how such curves might
affect quantum state evolution, entanglement preservation, and information
retention.
| [
{
"created": "Sun, 4 Aug 2024 19:09:43 GMT",
"version": "v1"
},
{
"created": "Thu, 8 Aug 2024 15:44:49 GMT",
"version": "v2"
}
] | 2024-08-09 | [
[
"Damle",
"Aviral",
""
],
[
"Law",
"Thomas",
""
]
] | This paper presents a speculative model exploring the behavior of quantum information for particles entering closed timelike curves (CTCs) in Kerr-Newman spacetime. We apply Gavassino's restoration principle to derive a theoretical framework for cyclic information dynamics within these extreme gravitational environments. Our model focuses specifically on particles that enter CTCs near the inner horizon of a Kerr-Newman black hole, examining how such curves might affect quantum state evolution, entanglement preservation, and information retention. |
0810.0297 | Tomas Liko | Tomas Liko, David Sloan | First-order action and Euclidean quantum gravity | 8 pages; v2: references added; minor corrections; v3: typos corrected
in eqns (20) and (21); v4: substantially revised; addition of NUT-charged
spacetimes; to appear in Classical and Quantum Gravity | Class.Quant.Grav.26:145004,2009 | 10.1088/0264-9381/26/14/145004 | IGC-08/10-1 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that the on-shell path integral for asymptotically flat Euclidean
spacetimes can be given in the first-order formulation of general relativity,
without assuming the boundary to be isometrically embedded in Euclidean space
and without adding infinite counter-terms. For illustrative examples of our
approach, we evaluate the first-order action for the four-dimensional Euclidean
Schwarzschild and NUT-charged spacetimes to derive the corresponding on-shell
partition functions, and show that the correct thermodynamic quantities for the
solutions are reproduced.
| [
{
"created": "Thu, 2 Oct 2008 00:09:10 GMT",
"version": "v1"
},
{
"created": "Wed, 8 Oct 2008 20:23:40 GMT",
"version": "v2"
},
{
"created": "Sat, 1 Nov 2008 22:04:02 GMT",
"version": "v3"
},
{
"created": "Thu, 28 May 2009 21:11:28 GMT",
"version": "v4"
}
] | 2009-07-22 | [
[
"Liko",
"Tomas",
""
],
[
"Sloan",
"David",
""
]
] | We show that the on-shell path integral for asymptotically flat Euclidean spacetimes can be given in the first-order formulation of general relativity, without assuming the boundary to be isometrically embedded in Euclidean space and without adding infinite counter-terms. For illustrative examples of our approach, we evaluate the first-order action for the four-dimensional Euclidean Schwarzschild and NUT-charged spacetimes to derive the corresponding on-shell partition functions, and show that the correct thermodynamic quantities for the solutions are reproduced. |
gr-qc/0605077 | Eric Poisson | Roland Haas and Eric Poisson | Mode-sum regularization of the scalar self-force: Formulation in terms
of a tetrad decomposition of the singular field | 38 pages, 2 figures | Phys.Rev. D74 (2006) 044009 | 10.1103/PhysRevD.74.044009 | null | gr-qc | null | We examine the motion in Schwarzschild spacetime of a point particle endowed
with a scalar charge. The particle produces a retarded scalar field which
interacts with the particle and influences its motion via the action of a
self-force. We exploit the spherical symmetry of the Schwarzschild spacetime
and decompose the scalar field in spherical-harmonic modes. Although each mode
is bounded at the position of the particle, a mode-sum evaluation of the
self-force requires regularization because the sum does not converge: the
retarded field is infinite at the position of the particle. The regularization
procedure involves the computation of regularization parameters, which are
obtained from a mode decomposition of the Detweiler-Whiting singular field;
these are subtracted from the modes of the retarded field, and the result is a
mode-sum that converges to the actual self-force. We present such a computation
in this paper. There are two main aspects of our work that are new. First, we
define the regularization parameters as scalar quantities by referring them to
a tetrad decomposition of the singular field. Second, we calculate four sets of
regularization parameters (denoted schematically by A, B, C, and D) instead of
the usual three (A, B, and C). As proof of principle that our methods are
reliable, we calculate the self-force acting on a scalar charge in circular
motion around a Schwarzschild black hole, and compare our answers with those
recorded in the literature.
| [
{
"created": "Fri, 12 May 2006 13:37:57 GMT",
"version": "v1"
},
{
"created": "Mon, 24 Jul 2006 18:07:49 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Haas",
"Roland",
""
],
[
"Poisson",
"Eric",
""
]
] | We examine the motion in Schwarzschild spacetime of a point particle endowed with a scalar charge. The particle produces a retarded scalar field which interacts with the particle and influences its motion via the action of a self-force. We exploit the spherical symmetry of the Schwarzschild spacetime and decompose the scalar field in spherical-harmonic modes. Although each mode is bounded at the position of the particle, a mode-sum evaluation of the self-force requires regularization because the sum does not converge: the retarded field is infinite at the position of the particle. The regularization procedure involves the computation of regularization parameters, which are obtained from a mode decomposition of the Detweiler-Whiting singular field; these are subtracted from the modes of the retarded field, and the result is a mode-sum that converges to the actual self-force. We present such a computation in this paper. There are two main aspects of our work that are new. First, we define the regularization parameters as scalar quantities by referring them to a tetrad decomposition of the singular field. Second, we calculate four sets of regularization parameters (denoted schematically by A, B, C, and D) instead of the usual three (A, B, and C). As proof of principle that our methods are reliable, we calculate the self-force acting on a scalar charge in circular motion around a Schwarzschild black hole, and compare our answers with those recorded in the literature. |
1009.2064 | Jeferson de Oliveira | Owen Pavel Fern\'andez Piedra and Jeferson de Oliveira | Fermion perturbations in string-theory black holes | 24 pages, 12 figures | Class.Quant.Grav.28:085023,2011 | 10.1088/0264-9381/28/8/085023 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we study fermion perturbations in four dimensional black holes
of string theory, obtained either from a non-extreme configuration of three
intersecting five-branes with a boost along the common string or from a
non-extreme intersecting system of two two-branes and two five-branes. The
Dirac equation for the massless neutrino field, after conformal re-scaling of
the metric, is written as a wave equation suitable to study the time evolution
of the perturbation. With the aid of Prony fitting of time-domain profile we
calculate the complex frequencies that dominate the quasinormal ringing stage,
and also determine this quantities by the semi-analytical sixth order WKB
method. We also find numerically the decay factor of fermion fields at very
late times, and show that the falloff is identical to those appeared for
massless fields in other four dimensional black hole spacetimes.
| [
{
"created": "Fri, 10 Sep 2010 17:39:21 GMT",
"version": "v1"
}
] | 2011-04-08 | [
[
"Piedra",
"Owen Pavel Fernández",
""
],
[
"de Oliveira",
"Jeferson",
""
]
] | In this paper we study fermion perturbations in four dimensional black holes of string theory, obtained either from a non-extreme configuration of three intersecting five-branes with a boost along the common string or from a non-extreme intersecting system of two two-branes and two five-branes. The Dirac equation for the massless neutrino field, after conformal re-scaling of the metric, is written as a wave equation suitable to study the time evolution of the perturbation. With the aid of Prony fitting of time-domain profile we calculate the complex frequencies that dominate the quasinormal ringing stage, and also determine this quantities by the semi-analytical sixth order WKB method. We also find numerically the decay factor of fermion fields at very late times, and show that the falloff is identical to those appeared for massless fields in other four dimensional black hole spacetimes. |
1711.06843 | lvc.publications | The LIGO Scientific Collaboration and the Virgo Collaboration: B. P.
Abbott, R. Abbott, T. D. Abbott, M. R. Abernathy, F. Acernese, K. Ackley, C.
Adams, T. Adams, P. Addesso, R. X. Adhikari, V. B. Adya, C. Affeldt, M.
Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith,
B. Allen, A. Allocca, P. A. Altin, A. Ananyeva, S. B. Anderson, W. G.
Anderson, S. Appert, K. Arai, M. C. Araya, J. S. Areeda, N. Arnaud, K. G.
Arun, S. Ascenzi, G. Ashton, M. Ast, S. M. Aston, P. Astone, P. Aufmuth, C.
Aulbert, A. Avila-Alvarez, S. Babak, P. Bacon, M. K. M. Bader, P. T. Baker,
F. Baldaccini, G. Ballardin, S. W. Ballmer, J. C. Barayoga, S. E. Barclay, B.
C. Barish, D. Barker, F. Barone, B. Barr, L. Barsotti, M. Barsuglia, D.
Barta, J. Bartlett, I. Bartos, R. Bassiri, A. Basti, J. C. Batch, C. Baune,
V. Bavigadda, M. Bazzan, C. Beer, M. Bejger, I. Belahcene, M. Belgin, A. S.
Bell, B. K. Berger, G. Bergmann, C. P. L. Berry, D. Bersanetti, A. Bertolini,
J. Betzwieser, S. Bhagwat, R. Bhandare, I. A. Bilenko, G. Billingsley, C. R.
Billman, J. Birch, R. Birney, O. Birnholtz, S. Biscans, A. Bisht, M. Bitossi,
C. Biwer, M. A. Bizouard, J. K. Blackburn, J. Blackman, C. D. Blair, D. G.
Blair, R. M. Blair, S. Bloemen, O. Bock, M. Boer, G. Bogaert, A. Bohe, F.
Bondu, R. Bonnand, B. A. Boom, R. Bork, V. Boschi, S. Bose, Y. Bouffanais, A.
Bozzi, C. Bradaschia, P. R. Brady, V. B. Braginsky, M. Branchesi, J. E. Brau,
T. Briant, A. Brillet, M. Brinkmann, V. Brisson, P. Brockill, J. E. Broida,
A. F. Brooks, D. A. Brown, D. D. Brown, N. M. Brown, S. Brunett, C. C.
Buchanan, A. Buikema, T. Bulik, H. J. Bulten, A. Buonanno, D. Buskulic, C.
Buy, R. L. Byer, M. Cabero, L. Cadonati, G. Cagnoli, C. Cahillane, J.
Calder'on Bustillo, T. A. Callister, E. Calloni, J. B. Camp, M. Canepa, K. C.
Cannon, H. Cao, J. Cao, C. D. Capano, E. Capocasa, F. Carbognani, S. Caride,
J. Casanueva Diaz, C. Casentini, S. Caudill, M. Cavagli`a, F. Cavalier, R.
Cavalieri, G. Cella, C. B. Cepeda, L. Cerboni Baiardi, G. Cerretani, E.
Cesarini, S. J. Chamberlin, M. Chan, S. Chao, P. Charlton, E.
Chassande-Mottin, B. D. Cheeseboro, H. Y. Chen, Y. Chen, H.-P. Cheng, A.
Chincarini, A. Chiummo, T. Chmiel, H. S. Cho, M. Cho, J. H. Chow, N.
Christensen, Q. Chu, A. J. K. Chua, S. Chua, S. Chung, G. Ciani, F. Clara, J.
A. Clark, F. Cleva, C. Cocchieri, E. Coccia, P.-F. Cohadon, A. Colla, C. G.
Collette, L. Cominsky, M. Constancio Jr., L. Conti, S. J. Cooper, T. R.
Corbitt, N. Cornish, A. Corsi, S. Cortese, C. A. Costa, M. W. Coughlin, S. B.
Coughlin, J.-P. Coulon, S. T. Countryman, P. Couvares, P. B. Covas, E. E.
Cowan, D. M. Coward, M. J. Cowart, D. C. Coyne, R. Coyne, J. D. E. Creighton,
T. D. Creighton, J. Cripe, S. G. Crowder, T. J. Cullen, A. Cumming, L.
Cunningham, E. Cuoco, T. Dal Canton, S. L. Danilishin, S. D'Antonio, K.
Danzmann, A. Dasgupta, C. F. Da Silva Costa, V. Dattilo, I. Dave, M. Davier,
G. S. Davies, D. Davis, E. J. Daw, B. Day, R. Day, S. De, D. DeBra, G.
Debreczeni, J. Degallaix, M. De Laurentis, S. Del'eglise, W. Del Pozzo, T.
Denker, T. Dent, V. Dergachev, R. De Rosa, R. T. DeRosa, R. DeSalvo, R. C.
Devine, S. Dhurandhar, M. C. D'iaz, L. Di Fiore, M. Di Giovanni, T. Di
Girolamo, A. Di Lieto, S. Di Pace, I. Di Palma, A. Di Virgilio, Z. Doctor, V.
Dolique, F. Donovan, K. L. Dooley, S. Doravari, I. Dorrington, R. Douglas, M.
Dovale 'Alvarez, T. P. Downes, M. Drago, R. W. P. Drever, J. C. Driggers, Z.
Du, M. Ducrot, S. E. Dwyer, T. B. Edo, M. C. Edwards, A. Effler, H.-B.
Eggenstein, P. Ehrens, J. Eichholz, S. S. Eikenberry, R. A. Eisenstein, R. C.
Essick, Z. Etienne, T. Etzel, M. Evans, T. M. Evans, R. Everett, M.
Factourovich, V. Fafone, H. Fair, S. Fairhurst, X. Fan, S. Farinon, B. Farr,
W. M. Farr, E. J. Fauchon-Jones, M. Favata, M. Fays, H. Fehrmann, M. M.
Fejer, A. Fern'andez Galiana, I. Ferrante, E. C. Ferreira, F. Ferrini, F.
Fidecaro, I. Fiori, D. Fiorucci, R. P. Fisher, R. Flaminio, M. Fletcher, H.
Fong, S. S. Forsyth, J.-D. Fournier, S. Frasca, F. Frasconi, Z. Frei, A.
Freise, R. Frey, V. Frey, E. M. Fries, P. Fritschel, V. V. Frolov, P. Fulda,
M. Fyffe, H. Gabbard, B. U. Gadre, S. M. Gaebel, J. R. Gair, L. Gammaitoni,
S. G. Gaonkar, F. Garufi, G. Gaur, V. Gayathri, N. Gehrels, G. Gemme, E.
Genin, A. Gennai, J. George, L. Gergely, V. Germain, S. Ghonge, Abhirup
Ghosh, Archisman Ghosh, S. Ghosh, J. A. Giaime, K. D. Giardina, A. Giazotto,
K. Gill, A. Glaefke, E. Goetz, R. Goetz, L. Gondan, G. Gonz'alez, J. M.
Gonzalez Castro, A. Gopakumar, M. L. Gorodetsky, S. E. Gossan, M. Gosselin,
R. Gouaty, A. Grado, C. Graef, M. Granata, A. Grant, S. Gras, C. Gray, G.
Greco, A. C. Green, P. Groot, H. Grote, S. Grunewald, G. M. Guidi, X. Guo, A.
Gupta, M. K. Gupta, K. E. Gushwa, E. K. Gustafson, R. Gustafson, J. J.
Hacker, B. R. Hall, E. D. Hall, G. Hammond, M. Haney, M. M. Hanke, J. Hanks,
C. Hanna, J. Hanson, T. Hardwick, J. Harms, G. M. Harry, I. W. Harry, M. J.
Hart, M. T. Hartman, C.-J. Haster, K. Haughian, J. Healy, A. Heidmann, M. C.
Heintze, H. Heitmann, P. Hello, G. Hemming, M. Hendry, I. S. Heng, J. Hennig,
J. Henry, A. W. Heptonstall, M. Heurs, S. Hild, D. Hoak, D. Hofman, K. Holt,
D. E. Holz, P. Hopkins, J. Hough, E. A. Houston, E. J. Howell, Y. M. Hu, E.
A. Huerta, D. Huet, B. Hughey, S. Husa, S. H. Huttner, T. Huynh-Dinh, N.
Indik, D. R. Ingram, R. Inta, H. N. Isa, J.-M. Isac, M. Isi, T. Isogai, B. R.
Iyer, K. Izumi, T. Jacqmin, K. Jani, P. Jaranowski, S. Jawahar, F.
Jim'enez-Forteza, W. W. Johnson, N. K. Johnson-McDaniel, D. I. Jones, R.
Jones, R. J. G. Jonker, L. Ju, J. Junker, C. V. Kalaghatgi, V. Kalogera, S.
Kandhasamy, G. Kang, J. B. Kanner, S. Karki, K. S. Karvinen, M. Kasprzack, E.
Katsavounidis, W. Katzman, S. Kaufer, T. Kaur, K. Kawabe, F. K'ef'elian, D.
Keitel, D. B. Kelley, R. Kennedy, J. S. Key, F. Y. Khalili, I. Khan, S. Khan,
Z. Khan, E. A. Khazanov, N. Kijbunchoo, Chunglee Kim, J. C. Kim, Whansun Kim,
W. Kim, Y.-M. Kim, S. J. Kimbrell, E. J. King, P. J. King, R. Kirchhoff, J.
S. Kissel, B. Klein, L. Kleybolte, S. Klimenko, P. Koch, S. M. Koehlenbeck,
S. Koley, V. Kondrashov, A. Kontos, M. Korobko, W. Z. Korth, I. Kowalska, D.
B. Kozak, C. Kr"amer, V. Kringel, B. Krishnan, A. Kr'olak, G. Kuehn, P.
Kumar, R. Kumar, L. Kuo, A. Kutynia, B. D. Lackey, M. Landry, R. N. Lang, J.
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Lazzarini, C. Lazzaro, P. Leaci, S. Leavey, E. O. Lebigot, C. H. Lee, H. K.
Lee, H. M. Lee, K. Lee, J. Lehmann, A. Lenon, M. Leonardi, J. R. Leong, N.
Leroy, N. Letendre, Y. Levin, T. G. F. Li, A. Libson, T. B. Littenberg, J.
Liu, N. A. Lockerbie, A. L. Lombardi, L. T. London, J. E. Lord, M. Lorenzini,
V. Loriette, M. Lormand, G. Losurdo, J. D. Lough, G. Lovelace, H. L"uck, A.
P. Lundgren, R. Lynch, Y. Ma, S. Macfoy, B. Machenschalk, M. MacInnis, D. M.
Macleod, F. Maga\~na-Sandoval, E. Majorana, I. Maksimovic, V. Malvezzi, N.
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T. J. Massinger, M. Masso-Reid, S. Mastrogiovanni, F. Matichard, L. Matone,
N. Mavalvala, N. Mazumder, R. McCarthy, D. E. McClelland, S. McCormick, C.
McGrath, S. C. McGuire, G. McIntyre, J. McIver, D. J. McManus, T. McRae, S.
T. McWilliams, D. Meacher, G. D. Meadors, J. Meidam, A. Melatos, G. Mendell,
D. Mendoza-Gandara, R. A. Mercer, E. L. Merilh, M. Merzougui, S. Meshkov, C.
Messenger, C. Messick, R. Metzdorff, P. M. Meyers, F. Mezzani, H. Miao, C.
Michel, H. Middleton, E. E. Mikhailov, L. Milano, A. L. Miller, A. Miller, B.
B. Miller, J. Miller, M. Millhouse, Y. Minenkov, J. Ming, S. Mirshekari, C.
Mishra, S. Mitra, V. P. Mitrofanov, G. Mitselmakher, R. Mittleman, A. Moggi,
M. Mohan, S. R. P. Mohapatra, M. Montani, B. C. Moore, C. J. Moore, D.
Moraru, G. Moreno, S. R. Morriss, B. Mours, C. M. Mow-Lowry, G. Mueller, A.
W. Muir, Arunava Mukherjee, D. Mukherjee, S. Mukherjee, N. Mukund, A.
Mullavey, J. Munch, E. A. M. Muniz, P. G. Murray, A. Mytidis, K. Napier, I.
Nardecchia, L. Naticchioni, G. Nelemans, T. J. N. Nelson, M. Neri, M. Nery,
A. Neunzert, J. M. Newport, G. Newton, T. T. Nguyen, A. B. Nielsen, S.
Nissanke, A. Nitz, A. Noack, F. Nocera, D. Nolting, M. E. N. Normandin, L. K.
Nuttall, J. Oberling, E. Ochsner, E. Oelker, G. H. Ogin, J. J. Oh, S. H. Oh,
F. Ohme, M. Oliver, P. Oppermann, Richard J. Oram, B. O'Reilly, R.
O'Shaughnessy, D. J. Ottaway, H. Overmier, B. J. Owen, A. E. Pace, J. Page,
A. Pai, S. A. Pai, J. R. Palamos, O. Palashov, C. Palomba, A. Pal-Singh, H.
Pan, C. Pankow, F. Pannarale, B. C. Pant, F. Paoletti, A. Paoli, M. A. Papa,
H. R. Paris, W. Parker, D. Pascucci, A. Pasqualetti, R. Passaquieti, D.
Passuello, B. Patricelli, B. L. Pearlstone, M. Pedraza, R. Pedurand, L.
Pekowsky, A. Pele, S. Penn, C. J. Perez, A. Perreca, L. M. Perri, H. P.
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Rowan, A. R"udiger, P. Ruggi, K. Ryan, S. Sachdev, T. Sadecki, L. Sadeghian,
M. Sakellariadou, L. Salconi, M. Saleem, F. Salemi, A. Samajdar, L. Sammut,
L. M. Sampson, E. J. Sanchez, V. Sandberg, J. R. Sanders, B. Sassolas, B. S.
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Schwalbe, J. Scott, S. M. Scott, D. Sellers, A. S. Sengupta, D. Sentenac, V.
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Shahriar, B. Shapiro, P. Shawhan, A. Sheperd, D. H. Shoemaker, D. M.
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Vyatchanin, A. R. Wade, L. E. Wade, M. Wade, M. Walker, L. Wallace, S. Walsh,
G. Wang, H. Wang, M. Wang, Y. Wang, R. L. Ward, J. Warner, M. Was, J. Watchi,
B. Weaver, L.-W. Wei, M. Weinert, A. J. Weinstein, R. Weiss, L. Wen, P.
Wessels, T. Westphal, K. Wette, J. T. Whelan, B. F. Whiting, C. Whittle, D.
Williams, R. D. Williams, A. R. Williamson, J. L. Willis, B. Willke, M. H.
Wimmer, W. Winkler, C. C. Wipf, H. Wittel, G. Woan, J. Woehler, J. Worden, J.
L. Wright, D. S. Wu, G. Wu, W. Yam, H. Yamamoto, C. C. Yancey, M. J. Yap,
Hang Yu, Haocun Yu, M. Yvert, A. Zadro.zny, L. Zangrando, M. Zanolin, J.-P.
Zendri, M. Zevin, L. Zhang, M. Zhang, T. Zhang, Y. Zhang, C. Zhao, M. Zhou,
Z. Zhou, S. J. Zhu, X. J. Zhu, M. E. Zucker, J. Zweizig | All-sky search for long-duration gravitational wave transients in the
first Advanced LIGO observing run | null | null | 10.1088/1361-6382/aaab76 | P1600277 | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present the results of a search for long-duration gravitational wave
transients in the data of the LIGO Hanford and LIGO Livingston second
generation detectors between September 2015 and January 2016, with a total
observational time of 49 days. The search targets gravitational wave transients
of \unit[10 -- 500]{s} duration in a frequency band of \unit[24 -- 2048]{Hz},
with minimal assumptions about the signal waveform, polarization, source
direction, or time of occurrence. No significant events were observed. %All
candidate triggers were consistent with the expected background, As a result we
set 90\% confidence upper limits on the rate of long-duration gravitational
wave transients for different types of gravitational wave signals. We also show
that the search is sensitive to sources in the Galaxy emitting at least $\sim$
\unit[$10^{-8}$]{$\mathrm{M_{\odot} c^2}$} in gravitational waves.
| [
{
"created": "Sat, 18 Nov 2017 10:36:31 GMT",
"version": "v1"
}
] | 2018-04-04 | [
[
"The LIGO Scientific Collaboration",
"",
""
],
[
"the Virgo Collaboration",
"",
""
],
[
"Abbott",
"B. P.",
""
],
[
"Abbott",
"R.",
""
],
[
"Abbott",
"T. D.",
""
],
[
"Abernathy",
"M. R.",
""
],
[
"Acernese",
"F... | We present the results of a search for long-duration gravitational wave transients in the data of the LIGO Hanford and LIGO Livingston second generation detectors between September 2015 and January 2016, with a total observational time of 49 days. The search targets gravitational wave transients of \unit[10 -- 500]{s} duration in a frequency band of \unit[24 -- 2048]{Hz}, with minimal assumptions about the signal waveform, polarization, source direction, or time of occurrence. No significant events were observed. %All candidate triggers were consistent with the expected background, As a result we set 90\% confidence upper limits on the rate of long-duration gravitational wave transients for different types of gravitational wave signals. We also show that the search is sensitive to sources in the Galaxy emitting at least $\sim$ \unit[$10^{-8}$]{$\mathrm{M_{\odot} c^2}$} in gravitational waves. |
1205.3263 | Pankaj S. Joshi | Pankaj S. Joshi and Ravindra V. Saraykar | Shell-crossings in Gravitational Collapse | 4 pages, typos corrected and references added | Int.J. of Mod.Phys. Volume 22, Issue 05, April 2013,1350027 | 10.1142/S0218271813500272 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | While studying the continual gravitational collapse of a massive matter cloud
in general relativity towards examining collapse final states, an important
issue is that of whether shell-crossing singularities can develop as the
collapse evolves. We examine this here to show that for any spherically
symmetric collapse in general, there is always a finite neighborhood of the
center in which there are no shell-crossings taking place. It follows that in
order to study the final genuine shell-focusing singularity of collapse where
the physical radius of the matter cloud shrinks to a vanishing value, we can
always consider without any loss of generality a collapsing ball of a finite
comoving radius in which there are no shell-crossings taking place. This
clarifies an important point for gravitational collapse studies.
| [
{
"created": "Tue, 15 May 2012 05:23:03 GMT",
"version": "v1"
},
{
"created": "Wed, 16 May 2012 14:54:15 GMT",
"version": "v2"
},
{
"created": "Mon, 29 Apr 2013 15:34:14 GMT",
"version": "v3"
}
] | 2013-04-30 | [
[
"Joshi",
"Pankaj S.",
""
],
[
"Saraykar",
"Ravindra V.",
""
]
] | While studying the continual gravitational collapse of a massive matter cloud in general relativity towards examining collapse final states, an important issue is that of whether shell-crossing singularities can develop as the collapse evolves. We examine this here to show that for any spherically symmetric collapse in general, there is always a finite neighborhood of the center in which there are no shell-crossings taking place. It follows that in order to study the final genuine shell-focusing singularity of collapse where the physical radius of the matter cloud shrinks to a vanishing value, we can always consider without any loss of generality a collapsing ball of a finite comoving radius in which there are no shell-crossings taking place. This clarifies an important point for gravitational collapse studies. |
0907.3292 | Jonathan R. Gair | Jonathan R Gair, Ilya Mandel, Alberto Sesana, Alberto Vecchio | Probing seed black holes using future gravitational-wave detectors | 14 pages, 6 figures, 2 tables, accepted for proceedings of 13th GWDAW
meeting | Class. Quantum Grav. 26 (2009) 204009 | 10.1088/0264-9381/26/20/204009 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Identifying the properties of the first generation of seeds of massive black
holes is key to understanding the merger history and growth of galaxies.
Mergers between ~100 solar mass seed black holes generate gravitational waves
in the 0.1-10Hz band that lies between the sensitivity bands of existing
ground-based detectors and the planned space-based gravitational wave detector,
the Laser Interferometer Space Antenna (LISA). However, there are proposals for
more advanced detectors that will bridge this gap, including the third
generation ground-based Einstein Telescope and the space-based detector DECIGO.
In this paper we demonstrate that such future detectors should be able to
detect gravitational waves produced by the coalescence of the first generation
of light seed black-hole binaries and provide information on the evolution of
structure in that era. These observations will be complementary to those that
LISA will make of subsequent mergers between more massive black holes. We
compute the sensitivity of various future detectors to seed black-hole mergers,
and use this to explore the number and properties of the events that each
detector might see in three years of observation. For this calculation, we make
use of galaxy merger trees and two different seed black hole mass distributions
in order to construct the astrophysical population of events. We also consider
the accuracy with which networks of future ground-based detectors will be able
to measure the parameters of seed black hole mergers, in particular the
luminosity distance to the source. We show that distance precisions of ~30% are
achievable, which should be sufficient for us to say with confidence that the
sources are at high redshift.
| [
{
"created": "Mon, 20 Jul 2009 15:05:47 GMT",
"version": "v1"
}
] | 2009-10-07 | [
[
"Gair",
"Jonathan R",
""
],
[
"Mandel",
"Ilya",
""
],
[
"Sesana",
"Alberto",
""
],
[
"Vecchio",
"Alberto",
""
]
] | Identifying the properties of the first generation of seeds of massive black holes is key to understanding the merger history and growth of galaxies. Mergers between ~100 solar mass seed black holes generate gravitational waves in the 0.1-10Hz band that lies between the sensitivity bands of existing ground-based detectors and the planned space-based gravitational wave detector, the Laser Interferometer Space Antenna (LISA). However, there are proposals for more advanced detectors that will bridge this gap, including the third generation ground-based Einstein Telescope and the space-based detector DECIGO. In this paper we demonstrate that such future detectors should be able to detect gravitational waves produced by the coalescence of the first generation of light seed black-hole binaries and provide information on the evolution of structure in that era. These observations will be complementary to those that LISA will make of subsequent mergers between more massive black holes. We compute the sensitivity of various future detectors to seed black-hole mergers, and use this to explore the number and properties of the events that each detector might see in three years of observation. For this calculation, we make use of galaxy merger trees and two different seed black hole mass distributions in order to construct the astrophysical population of events. We also consider the accuracy with which networks of future ground-based detectors will be able to measure the parameters of seed black hole mergers, in particular the luminosity distance to the source. We show that distance precisions of ~30% are achievable, which should be sufficient for us to say with confidence that the sources are at high redshift. |
1408.5762 | Michele Levi | Michele Levi, Jan Steinhoff | Equivalence of ADM Hamiltonian and Effective Field Theory approaches at
next-to-next-to-leading order spin1-spin2 coupling of binary inspirals | 44 pages; v2: published | JCAP 1412 (2014) 003 | 10.1088/1475-7516/2014/12/003 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The next-to-next-to-leading order spin1-spin2 potential for an inspiralling
binary, that is essential for accuracy to fourth post-Newtonian order, if both
components in the binary are spinning rapidly, has been recently derived
independently via the ADM Hamiltonian and the Effective Field Theory
approaches, using different gauges and variables. Here we show the complete
physical equivalence of the two results, thereby we first prove the equivalence
of the ADM Hamiltonian and the Effective Field Theory approaches at
next-to-next-to-leading order with the inclusion of spins. The main difficulty
in the spinning sectors, which also prescribes the manner in which the
comparison of the two results is tackled here, is the existence of redundant
unphysical spin degrees of freedom, associated with the spin gauge choice of a
point within the extended spinning object for its representative worldline.
After gauge fixing and eliminating the unphysical degrees of freedom of the
spin and its conjugate at the level of the action, we arrive at curved
spacetime generalizations of the Newton-Wigner variables in closed form, which
can also be used to obtain further Hamiltonians, based on an Effective Field
Theory formulation and computation. Finally, we make use of our validated
result to provide gauge invariant relations among the binding energy, angular
momentum, and orbital frequency of an inspiralling binary with generic compact
spinning components to fourth post-Newtonian order, including all known sectors
up to date.
| [
{
"created": "Mon, 25 Aug 2014 13:57:12 GMT",
"version": "v1"
},
{
"created": "Mon, 1 Dec 2014 17:51:09 GMT",
"version": "v2"
}
] | 2014-12-03 | [
[
"Levi",
"Michele",
""
],
[
"Steinhoff",
"Jan",
""
]
] | The next-to-next-to-leading order spin1-spin2 potential for an inspiralling binary, that is essential for accuracy to fourth post-Newtonian order, if both components in the binary are spinning rapidly, has been recently derived independently via the ADM Hamiltonian and the Effective Field Theory approaches, using different gauges and variables. Here we show the complete physical equivalence of the two results, thereby we first prove the equivalence of the ADM Hamiltonian and the Effective Field Theory approaches at next-to-next-to-leading order with the inclusion of spins. The main difficulty in the spinning sectors, which also prescribes the manner in which the comparison of the two results is tackled here, is the existence of redundant unphysical spin degrees of freedom, associated with the spin gauge choice of a point within the extended spinning object for its representative worldline. After gauge fixing and eliminating the unphysical degrees of freedom of the spin and its conjugate at the level of the action, we arrive at curved spacetime generalizations of the Newton-Wigner variables in closed form, which can also be used to obtain further Hamiltonians, based on an Effective Field Theory formulation and computation. Finally, we make use of our validated result to provide gauge invariant relations among the binding energy, angular momentum, and orbital frequency of an inspiralling binary with generic compact spinning components to fourth post-Newtonian order, including all known sectors up to date. |
0803.1929 | Ignacio S\'anchez-Rodr\'iguez | Ignacio Sanchez-Rodriguez | Geometrical Structures of Space-Time in General Relativity | To appear in the AIP Conference Proceedings of the XVI International
Fall Workshop on Geometry and Physics, Lisbon - Portugal, 5-8 September 2007.
5 pages | AIPConf.Proc.1023:202-206,2008 | 10.1063/1.2958176 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Space-Time in general relativity is a dynamical entity because it is subject
to the Einstein field equations. The space-time metric provides different
geometrical structures: conformal, volume, projective and linear connection. A
deep understanding of them has consequences on the dynamical role played by
geometry. We present a unified description of those geometrical structures,
with a standard criterion of naturalness, and then we establish relationships
among them and try to clarify the meaning of associated geometric magnitudes.
| [
{
"created": "Thu, 13 Mar 2008 09:27:37 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Sanchez-Rodriguez",
"Ignacio",
""
]
] | Space-Time in general relativity is a dynamical entity because it is subject to the Einstein field equations. The space-time metric provides different geometrical structures: conformal, volume, projective and linear connection. A deep understanding of them has consequences on the dynamical role played by geometry. We present a unified description of those geometrical structures, with a standard criterion of naturalness, and then we establish relationships among them and try to clarify the meaning of associated geometric magnitudes. |
2212.13391 | Kazufumi Takahashi | Kazufumi Takahashi, Rampei Kimura, Hayato Motohashi | Consistency of matter coupling in modified gravity | 11 pages | Phys. Rev. D 107, 044018 (2023) | 10.1103/PhysRevD.107.044018 | YITP-22-134 | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | Matter coupling in modified gravity theories is a nontrivial issue when the
gravitational Lagrangian possesses a degeneracy structure to avoid the problem
of the Ostrogradsky ghost. Recently, this issue was addressed for bosonic
matter fields in the generalized disformal Horndeski class, which is so far the
most general class of ghost-free scalar-tensor theories obtained by performing
a higher-derivative generalization of invertible disformal transformations on
Horndeski theories. In this paper, we clarify the consistency of fermionic
matter coupling in the generalized disformal Horndeski theories. We develop the
transformation law for the tetrad associated with the generalized disformal
transformation to see how it affects the fermionic matter coupling. We find
that the consistency of the fermionic matter coupling requires an additional
condition on top of the one required for the bosonic case. As a result, we
identify a subclass of the generalized disformal Horndeski class which allows
for consistent coupling of ordinary matter fields, including the standard model
particles.
| [
{
"created": "Tue, 27 Dec 2022 07:20:34 GMT",
"version": "v1"
},
{
"created": "Mon, 13 Feb 2023 05:01:08 GMT",
"version": "v2"
}
] | 2023-02-14 | [
[
"Takahashi",
"Kazufumi",
""
],
[
"Kimura",
"Rampei",
""
],
[
"Motohashi",
"Hayato",
""
]
] | Matter coupling in modified gravity theories is a nontrivial issue when the gravitational Lagrangian possesses a degeneracy structure to avoid the problem of the Ostrogradsky ghost. Recently, this issue was addressed for bosonic matter fields in the generalized disformal Horndeski class, which is so far the most general class of ghost-free scalar-tensor theories obtained by performing a higher-derivative generalization of invertible disformal transformations on Horndeski theories. In this paper, we clarify the consistency of fermionic matter coupling in the generalized disformal Horndeski theories. We develop the transformation law for the tetrad associated with the generalized disformal transformation to see how it affects the fermionic matter coupling. We find that the consistency of the fermionic matter coupling requires an additional condition on top of the one required for the bosonic case. As a result, we identify a subclass of the generalized disformal Horndeski class which allows for consistent coupling of ordinary matter fields, including the standard model particles. |
2402.02534 | Francisco Lobo | Jos\'e Tarciso S. S. Junior, Francisco S. N. Lobo, Manuel E. Rodrigues | Black holes and regular black holes in coincident
$f(\mathbb{Q},\mathbb{B}_Q)$ gravity coupled to nonlinear electrodynamics | 21 pages, 10 figures. V2: 25 pages, 15 figures; discussion and
references added. Accepted for publication in EPJC | Eur. Phys. J. C 84, 332 (2024) | 10.1140/epjc/s10052-024-12696-8 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we consider an extension of the symmetric teleparallel
equivalent of General Relativity (STEGR), namely, $f(\mathbb{Q})$ gravity, by
including a boundary term $\mathbb{B}_Q$, where $\mathbb{Q}$ is the
non-metricity scalar. More specifically, we explore static and spherically
symmetric black hole and regular black hole solutions in
$f(\mathbb{Q},\mathbb{B}_Q)$ gravity coupled to nonlinear electrodynamics
(NLED). In particular, to obtain black hole solutions, and in order to ensure
that our solutions preserve Lorentz symmetry, we assume the following relation
$f_Q = -f_B$, where $f_{Q}=\partial f/\partial\mathbb{Q}$ and $f_{B}= \partial
f/\partial\mathbb{B}_Q$. We develop three models of black holes, and as the
starting point for each case we consider the non-metricity scalar or the
boundary term in such a way to obtain the metric functions $A(r)$.
Additionally, we are able to express matter through analytical solutions for
specific NLED Lagrangians ${\cal L}_{\rm NLED}(F)$. Furthermore, we also obtain
generalized solutions of the Bardeen and Culetu types of regular black holes,
by imposing specific metric functions.
| [
{
"created": "Sun, 4 Feb 2024 15:27:51 GMT",
"version": "v1"
},
{
"created": "Mon, 18 Mar 2024 11:07:04 GMT",
"version": "v2"
}
] | 2024-04-01 | [
[
"Junior",
"José Tarciso S. S.",
""
],
[
"Lobo",
"Francisco S. N.",
""
],
[
"Rodrigues",
"Manuel E.",
""
]
] | In this work, we consider an extension of the symmetric teleparallel equivalent of General Relativity (STEGR), namely, $f(\mathbb{Q})$ gravity, by including a boundary term $\mathbb{B}_Q$, where $\mathbb{Q}$ is the non-metricity scalar. More specifically, we explore static and spherically symmetric black hole and regular black hole solutions in $f(\mathbb{Q},\mathbb{B}_Q)$ gravity coupled to nonlinear electrodynamics (NLED). In particular, to obtain black hole solutions, and in order to ensure that our solutions preserve Lorentz symmetry, we assume the following relation $f_Q = -f_B$, where $f_{Q}=\partial f/\partial\mathbb{Q}$ and $f_{B}= \partial f/\partial\mathbb{B}_Q$. We develop three models of black holes, and as the starting point for each case we consider the non-metricity scalar or the boundary term in such a way to obtain the metric functions $A(r)$. Additionally, we are able to express matter through analytical solutions for specific NLED Lagrangians ${\cal L}_{\rm NLED}(F)$. Furthermore, we also obtain generalized solutions of the Bardeen and Culetu types of regular black holes, by imposing specific metric functions. |
gr-qc/9501006 | Masayuki Tanimoto | Masayuki TANIMOTO | The role of Killing-Yano tensors in supersymmetric mechanics on a curved
manifold | 15 pages, ReVTeX, 1 figure | Nucl.Phys. B442 (1995) 549-562 | 10.1016/0550-3213(95)00086-8 | TIT/HEP-277/COSMO-50 | gr-qc hep-th | null | The supersymmetric extension of charged point particle's motion is applied to
investigate symmetries of gravitational fields and electromagnetic fields. We
mainly focus on the role of the Killing- Yano tensors of both usual and
generalized types. Results obtained by systematic analysis strengthen the
connection of the Killing- Yano tensor and superinvariants (functions commuting
with the supercharge).
| [
{
"created": "Tue, 10 Jan 1995 12:51:51 GMT",
"version": "v1"
},
{
"created": "Wed, 11 Jan 1995 13:31:12 GMT",
"version": "v2"
}
] | 2016-08-31 | [
[
"TANIMOTO",
"Masayuki",
""
]
] | The supersymmetric extension of charged point particle's motion is applied to investigate symmetries of gravitational fields and electromagnetic fields. We mainly focus on the role of the Killing- Yano tensors of both usual and generalized types. Results obtained by systematic analysis strengthen the connection of the Killing- Yano tensor and superinvariants (functions commuting with the supercharge). |
2211.16526 | Zhen Zhong | Zhen Zhong, Vitor Cardoso, Elisa Maggio | On the instability of ultracompact horizonless spacetimes | 13 pages, 12 figures, substantial improvements and clarifications.
Results remain unchanged: this work shows that a class of compact object
models are linearly stable when light rings are present but ergoregions are
absent. Version to appear in Physical Review D | null | 10.1103/PhysRevD.107.044035 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Motivated by recent results reporting the instability of horizonless objects
with stable light rings, we revisit the linearized stability of such
structures. In particular, we consider an exterior Kerr spacetime truncated at
a surface where Dirichlet conditions on a massless scalar are imposed.This
spacetime has ergoregions and light rings when the surface is placed
sufficiently deep in the gravitational potential. We establish that the
spacetime is linearly, mode-unstable when it is sufficiently compact, in a
mechanism associated with the ergoregion. In particular, such instability has
associated zero-modes. At large multipole number the critical surface location
for zero modes to exist is precisely the location of the ergosurface along the
equator. We show that such modes don't exist when the surface is outside the
ergoregion, and that any putative linear instability mechanism acts on
timescales $\tau \gtrsim 10^5 M$, where $M$ is the black hole mass. Our results
indicate therefore that at least certain classes of objects are linearly stable
in the absence of ergoregions, even if rotation and light rings are present.
| [
{
"created": "Tue, 29 Nov 2022 19:00:03 GMT",
"version": "v1"
},
{
"created": "Sun, 4 Dec 2022 13:38:44 GMT",
"version": "v2"
},
{
"created": "Mon, 6 Feb 2023 15:56:38 GMT",
"version": "v3"
}
] | 2023-03-01 | [
[
"Zhong",
"Zhen",
""
],
[
"Cardoso",
"Vitor",
""
],
[
"Maggio",
"Elisa",
""
]
] | Motivated by recent results reporting the instability of horizonless objects with stable light rings, we revisit the linearized stability of such structures. In particular, we consider an exterior Kerr spacetime truncated at a surface where Dirichlet conditions on a massless scalar are imposed.This spacetime has ergoregions and light rings when the surface is placed sufficiently deep in the gravitational potential. We establish that the spacetime is linearly, mode-unstable when it is sufficiently compact, in a mechanism associated with the ergoregion. In particular, such instability has associated zero-modes. At large multipole number the critical surface location for zero modes to exist is precisely the location of the ergosurface along the equator. We show that such modes don't exist when the surface is outside the ergoregion, and that any putative linear instability mechanism acts on timescales $\tau \gtrsim 10^5 M$, where $M$ is the black hole mass. Our results indicate therefore that at least certain classes of objects are linearly stable in the absence of ergoregions, even if rotation and light rings are present. |
2311.17207 | Raikhik Das | Raikhik Das | Classical Soft Graviton Theorem to Memory Effect and Violation of
Peeling | 8 pages, LaTeX; few typos corrected | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by-nc-sa/4.0/ | It has been known for some time that the asymptotic structure of spacetime
and soft theorems are closely related. To study the structure of future null
infinity, studying the classical soft graviton theorem is often quite helpful.
The memory effect at the future null infinity can be demonstrated from the
leading behavior of gravitational radiation low-frequency. However, the memory
effect is not the only information we can get from soft gravitational
radiation. This paper demonstrates how the classical soft graviton theorem
enlightens us about the memory effect and the differential structure of the
future null infinity.
| [
{
"created": "Tue, 28 Nov 2023 20:21:33 GMT",
"version": "v1"
},
{
"created": "Thu, 30 Nov 2023 07:18:46 GMT",
"version": "v2"
}
] | 2023-12-01 | [
[
"Das",
"Raikhik",
""
]
] | It has been known for some time that the asymptotic structure of spacetime and soft theorems are closely related. To study the structure of future null infinity, studying the classical soft graviton theorem is often quite helpful. The memory effect at the future null infinity can be demonstrated from the leading behavior of gravitational radiation low-frequency. However, the memory effect is not the only information we can get from soft gravitational radiation. This paper demonstrates how the classical soft graviton theorem enlightens us about the memory effect and the differential structure of the future null infinity. |
2405.07480 | Tim Koslowski A | Julian Barbour, Zaza Doborjginidze, Tim Koslowski, Hemant Shukla | Complexity and Its Creation | 16 pages, Latex, 4 figures | null | null | null | gr-qc cond-mat.stat-mech | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Except for crystalline or random structures, an agreed definition of
complexity for intermediate and hence interesting cases does not exist. We fill
this gap with a notion of complexity that characterises shapes formed by any
finite number of particles greater than or equal to the three needed to define
triangle shapes. The resulting shape complexity is a simple scale-invariant
quantity that measures the extent to which a collection of particles has a
uniform or clustered distribution. As a positive-definite number with an
absolute minimum realised on the most uniform distribution the particles can
have, it not only characterises all physical structures from crystals to the
most complex that can exist but also determines for them a measure that makes
richly structured shapes more probable than bland ones. Strikingly, the
criterion employed to define the shape complexity forces it to be the product
of the two functions that define Newtonian universal gravitation. This suggests
both the form and solutions the law of a universe of such particles should have
and leads to a theory that not only determines the complexity and probability
of any individual shape but also its creation from the maximally uniform shape.
It does this moreover in a manner which makes it probable that the cosmological
principle, according to which on a sufficiently large scale the universe should
have the same appearance everywhere, holds. Our theory relies on universal
group-theoretical principles that may allow generalisation to include all
forces and general relativity.
| [
{
"created": "Mon, 13 May 2024 05:47:57 GMT",
"version": "v1"
}
] | 2024-05-14 | [
[
"Barbour",
"Julian",
""
],
[
"Doborjginidze",
"Zaza",
""
],
[
"Koslowski",
"Tim",
""
],
[
"Shukla",
"Hemant",
""
]
] | Except for crystalline or random structures, an agreed definition of complexity for intermediate and hence interesting cases does not exist. We fill this gap with a notion of complexity that characterises shapes formed by any finite number of particles greater than or equal to the three needed to define triangle shapes. The resulting shape complexity is a simple scale-invariant quantity that measures the extent to which a collection of particles has a uniform or clustered distribution. As a positive-definite number with an absolute minimum realised on the most uniform distribution the particles can have, it not only characterises all physical structures from crystals to the most complex that can exist but also determines for them a measure that makes richly structured shapes more probable than bland ones. Strikingly, the criterion employed to define the shape complexity forces it to be the product of the two functions that define Newtonian universal gravitation. This suggests both the form and solutions the law of a universe of such particles should have and leads to a theory that not only determines the complexity and probability of any individual shape but also its creation from the maximally uniform shape. It does this moreover in a manner which makes it probable that the cosmological principle, according to which on a sufficiently large scale the universe should have the same appearance everywhere, holds. Our theory relies on universal group-theoretical principles that may allow generalisation to include all forces and general relativity. |
gr-qc/9506042 | Paulo Rodrigues Lima Vargas Moniz | P.V. Moniz | The Case of the Missing Wormhole State | 17 pages, Talk given at the 6th Moskow Quantum Gravity Seminar,
Moskow 12-19 June 1995, Russia; some problems with TeX fonts may occur, just
press return | Gen.Rel.Grav.28:97-115,1996 | 10.1007/BF02106857 | reduced version of DAMTP R95/19 | gr-qc | null | The issue concerning the existence of wormhole states in locally
supersymmetric minisuperspace models with matter is addressed. Wormhole states
are apparently absent in models obtained from the more general theory of N=1
supergravity with supermatter. A Hartle-Hawking type solution can be found,
even though some terms (which are scalar field dependent) cannot be determined
in a satisfactory way. A possible cause is investigated here. As far as the
wormhole situation is concerned, we argue here that the type of Lagrange
multipliers and fermionic derivative ordering one uses may make a difference. A
proposal is made for supersymmetric quantum wormholes to also be invested with
a Hilbert space structure, associated with a maximal analytical extension of
the corresponding minisuperspace.
| [
{
"created": "Wed, 21 Jun 1995 14:07:25 GMT",
"version": "v1"
}
] | 2011-04-15 | [
[
"Moniz",
"P. V.",
""
]
] | The issue concerning the existence of wormhole states in locally supersymmetric minisuperspace models with matter is addressed. Wormhole states are apparently absent in models obtained from the more general theory of N=1 supergravity with supermatter. A Hartle-Hawking type solution can be found, even though some terms (which are scalar field dependent) cannot be determined in a satisfactory way. A possible cause is investigated here. As far as the wormhole situation is concerned, we argue here that the type of Lagrange multipliers and fermionic derivative ordering one uses may make a difference. A proposal is made for supersymmetric quantum wormholes to also be invested with a Hilbert space structure, associated with a maximal analytical extension of the corresponding minisuperspace. |
1810.06244 | Pradip Mukherjee | Pradip Mukherjee and Abdus Sattar | Constrained Hamiltonian analysis of a non relativistic Schrodinger field
coupled with C-S gravity | 19 pages, Latex. This version is to remedy a mess in v3 which is
spurious. This version is a considerably revised form of v2. Ignore v3 | Phys. Rev. D 99, 084038 (2019) | 10.1103/PhysRevD.99.084038 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide a constrained Hamiltonian analysis of a non relativistic
Schrodinger field in 2+1 dimensions , coupled with Chern - Simons gravity. The
coupling is achieved by the recently advanced Galilean gauge theory
\cite{BMM1},\cite{ BMM2}, \cite{BM4}. The calculations are repeated with a
truncated model to show that deviation from Galilean gauge theory makes the
theory untenable. The issue of nonrelativistic spatial diffeomorphism is
discussed in this context.
| [
{
"created": "Mon, 15 Oct 2018 09:42:52 GMT",
"version": "v1"
},
{
"created": "Tue, 16 Oct 2018 04:10:50 GMT",
"version": "v2"
},
{
"created": "Fri, 30 Nov 2018 12:27:34 GMT",
"version": "v3"
},
{
"created": "Wed, 2 Jan 2019 04:31:47 GMT",
"version": "v4"
}
] | 2019-04-24 | [
[
"Mukherjee",
"Pradip",
""
],
[
"Sattar",
"Abdus",
""
]
] | We provide a constrained Hamiltonian analysis of a non relativistic Schrodinger field in 2+1 dimensions , coupled with Chern - Simons gravity. The coupling is achieved by the recently advanced Galilean gauge theory \cite{BMM1},\cite{ BMM2}, \cite{BM4}. The calculations are repeated with a truncated model to show that deviation from Galilean gauge theory makes the theory untenable. The issue of nonrelativistic spatial diffeomorphism is discussed in this context. |
1202.2301 | Cenalo Vaz | Kinjalk Lochan, Cenalo Vaz | Canonical Partition function of Loop Black Holes | 16 pages, 1 figure. Some clarifications and references added. To
appear in Phys. Rev. D | Phys. Rev. D 85 (2012) 104041 | 10.1103/PhysRevD.85.104041 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compute the canonical partition for quantum black holes in the approach of
Loop Quantum Gravity (LQG). We argue that any quantum theory of gravity in
which the horizon area is built of non-interacting constituents cannot yield
qualitative corrections to the Bekenstein-Hawking (B-H) area law, but
corrections to the area law can arise as a consequence additional constraints
inducing interactions between the constituents. In LQG this is implemented by
requiring spherical horizons. The canonical approach for LQG favours a
logarithmic correction to the B-H law with a coefficient of -1/2, independently
of the area spectrum. Our initial calculation of the partition function uses
certain approximations that, we show, do not qualitatively affect the
expression for the black hole entropy. We later discuss the quantitative
corrections to these results when the simplifying approximations are relaxed
and the full LQG spectrum is dealt with. We show how these corrections can be
recovered to all orders in perturbation theory. However, the convergence
properties of the perturbative series remains unknown.
| [
{
"created": "Fri, 10 Feb 2012 16:40:40 GMT",
"version": "v1"
},
{
"created": "Wed, 2 May 2012 18:51:23 GMT",
"version": "v2"
}
] | 2012-06-25 | [
[
"Lochan",
"Kinjalk",
""
],
[
"Vaz",
"Cenalo",
""
]
] | We compute the canonical partition for quantum black holes in the approach of Loop Quantum Gravity (LQG). We argue that any quantum theory of gravity in which the horizon area is built of non-interacting constituents cannot yield qualitative corrections to the Bekenstein-Hawking (B-H) area law, but corrections to the area law can arise as a consequence additional constraints inducing interactions between the constituents. In LQG this is implemented by requiring spherical horizons. The canonical approach for LQG favours a logarithmic correction to the B-H law with a coefficient of -1/2, independently of the area spectrum. Our initial calculation of the partition function uses certain approximations that, we show, do not qualitatively affect the expression for the black hole entropy. We later discuss the quantitative corrections to these results when the simplifying approximations are relaxed and the full LQG spectrum is dealt with. We show how these corrections can be recovered to all orders in perturbation theory. However, the convergence properties of the perturbative series remains unknown. |
1201.6091 | Prado Martin-Moruno | Prado Martin-Moruno | Could a foliation by constant mean curvature hypersurfaces cover the
existence of most observers in our part of spacetime? | 4 pages, 1 figure, to appear in Proceedings of Spanish Relativity
Meeting 2011 (ERE 2011) held in Madrid, Spain | AIP Conf.Proc. 1458 (2011) 471-474 | 10.1063/1.4734462 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a foliation by constant mean curvature hypersurfaces of a de
Sitter space with a thin-wall Coleman-De Luccia bubble of de Sitter space
inside, which covers the existence of most observers in our part of spacetime
if we are placed in the region outside the bubble.
| [
{
"created": "Sun, 29 Jan 2012 23:56:22 GMT",
"version": "v1"
}
] | 2012-12-06 | [
[
"Martin-Moruno",
"Prado",
""
]
] | We present a foliation by constant mean curvature hypersurfaces of a de Sitter space with a thin-wall Coleman-De Luccia bubble of de Sitter space inside, which covers the existence of most observers in our part of spacetime if we are placed in the region outside the bubble. |
gr-qc/0209044 | Ion Vasile Vancea | M. C. B. Abdalla, M. A. De Andrade, M. A. Santos, I. V. Vancea | On The Symplectic Two-Form of Gravity in Terms of Dirac Eigenvalues | misprints corrected, final interpretation of results given | Phys.Lett. B548 (2002) 88-91 | 10.1016/S0370-2693(02)02817-4 | null | gr-qc | null | The Dirac eigenvalues form a subset of observables of the Euclidean gravity.
The symplectic two-form in the covariant phase space could be expressed, in
principle, in terms of the Dirac eigenvalues. We discuss the existence of the
formal solution of the equations defining the components of the symplectic form
in this framework.
| [
{
"created": "Thu, 12 Sep 2002 20:08:20 GMT",
"version": "v1"
},
{
"created": "Wed, 25 Sep 2002 14:50:10 GMT",
"version": "v2"
}
] | 2009-11-07 | [
[
"Abdalla",
"M. C. B.",
""
],
[
"De Andrade",
"M. A.",
""
],
[
"Santos",
"M. A.",
""
],
[
"Vancea",
"I. V.",
""
]
] | The Dirac eigenvalues form a subset of observables of the Euclidean gravity. The symplectic two-form in the covariant phase space could be expressed, in principle, in terms of the Dirac eigenvalues. We discuss the existence of the formal solution of the equations defining the components of the symplectic form in this framework. |
1806.10902 | Sergey Paston | S.A. Paston, A.A. Sheykin | Embedding theory as new geometrical mimetic gravity | LaTeX, 11 pages | European Physical Journal C 78 (2018) 989 | 10.1140/epjc/s10052-018-6474-9 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is known that recently proposed model of mimetic gravity can be presented
as general relativity with an additional mimetic matter. We discuss a
possibility to analogously reformulate the embedding theory, which is the
geometrical description of gravity proposed by Regge and Teitelboim, treating
it also as general relativity with some additional matter. We propose a form of
action which allows to describe this matter in terms of conserved currents.
This action turns out to be a generalization of the perfect fluid action, which
can be useful in the analysis of the properties of the additional matter. On
the other side, the action contains a trace of the root of the matrix product,
which is similar to the constructions appearing in bimetric theories of
gravity. The action is completely equivalent to the original embedding theory,
so it is not just some artificial model, but has a clear geometric sense. We
discuss the possible equivalent forms of the theory and ways of study of the
appearing equations of motion.
| [
{
"created": "Thu, 28 Jun 2018 11:58:58 GMT",
"version": "v1"
},
{
"created": "Thu, 6 Dec 2018 18:35:05 GMT",
"version": "v2"
}
] | 2018-12-07 | [
[
"Paston",
"S. A.",
""
],
[
"Sheykin",
"A. A.",
""
]
] | It is known that recently proposed model of mimetic gravity can be presented as general relativity with an additional mimetic matter. We discuss a possibility to analogously reformulate the embedding theory, which is the geometrical description of gravity proposed by Regge and Teitelboim, treating it also as general relativity with some additional matter. We propose a form of action which allows to describe this matter in terms of conserved currents. This action turns out to be a generalization of the perfect fluid action, which can be useful in the analysis of the properties of the additional matter. On the other side, the action contains a trace of the root of the matrix product, which is similar to the constructions appearing in bimetric theories of gravity. The action is completely equivalent to the original embedding theory, so it is not just some artificial model, but has a clear geometric sense. We discuss the possible equivalent forms of the theory and ways of study of the appearing equations of motion. |
1205.2001 | Cecilia Chirenti | Cecilia Chirenti, Patrick R. Silveira and Odylio D. Aguiar | Non-radial oscillations of neutron stars and the detection of
gravitational waves | 5 pages, 3 figures. Prepared for the proceedings of the 5th
International Workshop on Astronomy and Relativistic Astrophysics, Joao
Pessoa, Brazil, October 9-12, 2011 | null | 10.1142/S2010194512008185 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the non-radial oscillations of relativistic neutron stars, in
particular the (fundamental) f-modes, which are believed to be the most
relevant for the gravitational wave emission of perturbed isolated stars. The
expected frequencies of the f-modes are compared to the sensitivity range of
Mario Schenberg, the Brazilian gravitational wave spherical detector.
| [
{
"created": "Wed, 9 May 2012 14:48:41 GMT",
"version": "v1"
}
] | 2015-06-05 | [
[
"Chirenti",
"Cecilia",
""
],
[
"Silveira",
"Patrick R.",
""
],
[
"Aguiar",
"Odylio D.",
""
]
] | We study the non-radial oscillations of relativistic neutron stars, in particular the (fundamental) f-modes, which are believed to be the most relevant for the gravitational wave emission of perturbed isolated stars. The expected frequencies of the f-modes are compared to the sensitivity range of Mario Schenberg, the Brazilian gravitational wave spherical detector. |
gr-qc/9403007 | Hkitada | Hitoshi Kitada | Theory of Local Times II. Another formulation and examples | 22 pages, LaTeX, revised in minor descriptions | null | null | KIMS-1994-03-03 | gr-qc astro-ph hep-th | null | The model of a stationary universe and the notion of local times presented in
[10] are reviewed with some alternative formulation of the consistent
unification of the Riemannian and Euclidean geometries of general relativity
and quantum mechanics. The method of unification adopted in the present paper
is by constructing a vector bundle $X\times R^6$ or $X\times R^4$ with $X$
being the observer's reference frame and $R^6$ or $R^4$ being the unobservable
inner space(-time) within each observer's local system. Some applications of
our theory to two concrete examples of human size and of cosmological size are
discussed, as well as the uncertainty of time in our context is calculated.
| [
{
"created": "Wed, 2 Mar 1994 13:05:49 GMT",
"version": "v1"
},
{
"created": "Mon, 22 May 1995 09:10:51 GMT",
"version": "v2"
}
] | 2008-02-03 | [
[
"Kitada",
"Hitoshi",
""
]
] | The model of a stationary universe and the notion of local times presented in [10] are reviewed with some alternative formulation of the consistent unification of the Riemannian and Euclidean geometries of general relativity and quantum mechanics. The method of unification adopted in the present paper is by constructing a vector bundle $X\times R^6$ or $X\times R^4$ with $X$ being the observer's reference frame and $R^6$ or $R^4$ being the unobservable inner space(-time) within each observer's local system. Some applications of our theory to two concrete examples of human size and of cosmological size are discussed, as well as the uncertainty of time in our context is calculated. |
0707.0201 | Trevor W. Marshall | Trevor W. Marshall | Gravitational waves versus black holes | null | null | null | null | gr-qc | null | It is argued that, in order for the gravitational field to be propagated as a
wave, it is necessary for it to satisfy a further set of field equations, in
addition to those of Einstein and Hilbert, and these equations mean there is a
preferred coordinate frame, called the Global Inertial Frame, giving rise to a
unique metric . The implication is that a true gravitational field is not
compatible with Einstein's Principle of Equivalence, which is in contradiction
with his other fundamental concept of locality. The additional field equations
ensure that gravitational collapse does not go below the Schwarzschild radius,
thereby excluding the possibility of singular solutions (black holes) of the
Einstein-Hilbert equations. Such solutions would also violate Einstein's
locality principle.
| [
{
"created": "Mon, 2 Jul 2007 11:57:30 GMT",
"version": "v1"
}
] | 2007-07-03 | [
[
"Marshall",
"Trevor W.",
""
]
] | It is argued that, in order for the gravitational field to be propagated as a wave, it is necessary for it to satisfy a further set of field equations, in addition to those of Einstein and Hilbert, and these equations mean there is a preferred coordinate frame, called the Global Inertial Frame, giving rise to a unique metric . The implication is that a true gravitational field is not compatible with Einstein's Principle of Equivalence, which is in contradiction with his other fundamental concept of locality. The additional field equations ensure that gravitational collapse does not go below the Schwarzschild radius, thereby excluding the possibility of singular solutions (black holes) of the Einstein-Hilbert equations. Such solutions would also violate Einstein's locality principle. |
0802.3314 | Carlos Kozameh | C. Kozameh, E. T. Newman, G. Silva-Ortigoza | On Extracting Physical Content from Asymptotically Flat Space-Time
Metrics | 33 pages | Class.Quant.Grav.25:145001,2008 | 10.1088/0264-9381/25/14/145001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A major issue in general relativity, from its earliest days to the present,
is how to extract physical information from any solution or class of solutions
to the Einstein equations. Though certain information can be obtained for
arbitrary solutions, e.g., via geodesic deviation, in general, because of the
coordinate freedom, it is often hard or impossible to do. Most of the time
information is found from special conditions, e.g., degenerate principle null
vectors, weak fields close to Minkowski space (using coordinates close to
Minkowski coordinates) or from solutions that have symmetries or approximate
symmetries. In the present work we will be concerned with asymptotically flat
space times where the approximate symmetry is the Bondi-Metzner-Sachs (BMS)
group. For these spaces the Bondi four-momentum vector and its evolution, found
from the Weyl tensor at infinity, describes the total energy-momentum of the
interior source and the energy-momentum radiated. By generalizing the
structures (shear-free null geodesic congruences) associated with the
algebraically special metrics to asymptotically shear-free null geodesic
congruences, which are available in all asymptotically flat space-times, we
give kinematic meaning to the Bondi four-momentum. In other words we describe
the Bondi vector and its evolution in terms of a center of mass position
vector, its velocity and a spin-vector, all having clear geometric meaning.
Among other items, from dynamic arguments, we define a unique (at our level of
approximation) total angular momentum and extract its evolution equation in the
form of a conservation law with an angular momentum flux.
| [
{
"created": "Fri, 22 Feb 2008 13:39:05 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Kozameh",
"C.",
""
],
[
"Newman",
"E. T.",
""
],
[
"Silva-Ortigoza",
"G.",
""
]
] | A major issue in general relativity, from its earliest days to the present, is how to extract physical information from any solution or class of solutions to the Einstein equations. Though certain information can be obtained for arbitrary solutions, e.g., via geodesic deviation, in general, because of the coordinate freedom, it is often hard or impossible to do. Most of the time information is found from special conditions, e.g., degenerate principle null vectors, weak fields close to Minkowski space (using coordinates close to Minkowski coordinates) or from solutions that have symmetries or approximate symmetries. In the present work we will be concerned with asymptotically flat space times where the approximate symmetry is the Bondi-Metzner-Sachs (BMS) group. For these spaces the Bondi four-momentum vector and its evolution, found from the Weyl tensor at infinity, describes the total energy-momentum of the interior source and the energy-momentum radiated. By generalizing the structures (shear-free null geodesic congruences) associated with the algebraically special metrics to asymptotically shear-free null geodesic congruences, which are available in all asymptotically flat space-times, we give kinematic meaning to the Bondi four-momentum. In other words we describe the Bondi vector and its evolution in terms of a center of mass position vector, its velocity and a spin-vector, all having clear geometric meaning. Among other items, from dynamic arguments, we define a unique (at our level of approximation) total angular momentum and extract its evolution equation in the form of a conservation law with an angular momentum flux. |
1201.4017 | Amit Ghosh | Bhramar Chatterjee and Amit Ghosh | Near-extremal black holes | 14 pages | null | 10.1007/JHEP04(2012)125 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a new formulation of deriving Hawking temperature for
near-extremal black holes using distributions. In this paper the near-extremal
Reissner-Nordstrom and Kerr black holes are discussed. It is shown that the
extremal solution as a limit of non-extremal metric is well-defined. The pure
extremal case is also discussed separately.
| [
{
"created": "Thu, 19 Jan 2012 10:43:10 GMT",
"version": "v1"
}
] | 2015-06-03 | [
[
"Chatterjee",
"Bhramar",
""
],
[
"Ghosh",
"Amit",
""
]
] | We present a new formulation of deriving Hawking temperature for near-extremal black holes using distributions. In this paper the near-extremal Reissner-Nordstrom and Kerr black holes are discussed. It is shown that the extremal solution as a limit of non-extremal metric is well-defined. The pure extremal case is also discussed separately. |
1502.04630 | Shahen Hacyan | Shahen Hacyan | Effects of gravitational waves on the polarization of pulsars | null | null | 10.1142/S0217751X16410232 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The polarization of electromagnetic waves in the presence of a gravitational
wave is analyzed. The rotation of the polarization angle and the Stokes
parameters are deduced. A possible application to the detection of stochastic
background of gravitational waves is proposed as a complement to the pulsar
timing method.
| [
{
"created": "Mon, 16 Feb 2015 17:08:39 GMT",
"version": "v1"
}
] | 2016-02-03 | [
[
"Hacyan",
"Shahen",
""
]
] | The polarization of electromagnetic waves in the presence of a gravitational wave is analyzed. The rotation of the polarization angle and the Stokes parameters are deduced. A possible application to the detection of stochastic background of gravitational waves is proposed as a complement to the pulsar timing method. |
1112.1057 | Alan J. Weinstein | Alan J. Weinstein (for the LIGO Scientific Collaboration, and for the
Virgo Collaboration) | Astronomy and astrophysics with gravitational waves in the Advanced
Detector Era | 10 pages, no figures. Submitted to the proceedings of the 9th Edoardo
Amaldi Conference on Gravitational Waves, and the 2011 Numerical Relativity -
Data Analysis (NRDA) meeting, held 10-15 July 2011 in Cardiff, Wales, UK,
July 10-15 2011 (Special issue of CQG). Updated in response to CQG referees
and CQG proofs. Accepted by CQG | Class. Quantum Grav. 29 (2012) 124012 | 10.1088/0264-9381/29/12/124012 | LIGO Document P1100189 | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | With the advanced gravitational wave detectors coming on line in the next 5
years, we expect to make the first detections of gravitational waves from
astrophysical sources, and study the properties of the waves themselves as
tests of General Relativity. In addition, these gravitational waves will be
powerful tools for the study of their astrophysical sources and source
populations. They carry information that is quite complementary to what can be
learned from electromagnetic or neutrino observations, probing the central
gravitational engines that power the electromagnetic emissions. Preparations
are being made to enable near-simultaneous observations of both gravitational
wave and electromagnetic observations of transient sources, using low-latency
search pipelines and rapid sky localization. We will review the many
opportunities for multi-messenger astronomy and astrophysics with gravitational
waves enabled by the advanced detectors, and the preparations that are being
made to quickly and fully exploit them.
| [
{
"created": "Mon, 5 Dec 2011 20:48:11 GMT",
"version": "v1"
},
{
"created": "Fri, 24 Feb 2012 21:35:34 GMT",
"version": "v2"
},
{
"created": "Mon, 12 Mar 2012 21:25:14 GMT",
"version": "v3"
}
] | 2019-08-15 | [
[
"Weinstein",
"Alan J.",
"",
"for the LIGO Scientific Collaboration, and for the\n Virgo Collaboration"
]
] | With the advanced gravitational wave detectors coming on line in the next 5 years, we expect to make the first detections of gravitational waves from astrophysical sources, and study the properties of the waves themselves as tests of General Relativity. In addition, these gravitational waves will be powerful tools for the study of their astrophysical sources and source populations. They carry information that is quite complementary to what can be learned from electromagnetic or neutrino observations, probing the central gravitational engines that power the electromagnetic emissions. Preparations are being made to enable near-simultaneous observations of both gravitational wave and electromagnetic observations of transient sources, using low-latency search pipelines and rapid sky localization. We will review the many opportunities for multi-messenger astronomy and astrophysics with gravitational waves enabled by the advanced detectors, and the preparations that are being made to quickly and fully exploit them. |
gr-qc/0107085 | Hideki Ishihara | Hideki Ishihara | Big bang of the brane universe | LaTeX, 11 pages, 3 EPS figures | Phys.Rev. D66 (2002) 023513 | 10.1103/PhysRevD.66.023513 | null | gr-qc hep-th | null | Big bang of the Friedmann-Robertson-Walker (FRW)-brane universe is studied.
In contrast to the spacelike initial singularity of the usual FRW universe, the
initial singularity of the FRW-brane universe is point-like from the viewpoint
of causality including gravitational waves propagating in the bulk. Existence
of null singularities (seam singuralities) is also shown in the flat and open
FRW-brane universe models.
| [
{
"created": "Thu, 26 Jul 2001 09:10:11 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Ishihara",
"Hideki",
""
]
] | Big bang of the Friedmann-Robertson-Walker (FRW)-brane universe is studied. In contrast to the spacelike initial singularity of the usual FRW universe, the initial singularity of the FRW-brane universe is point-like from the viewpoint of causality including gravitational waves propagating in the bulk. Existence of null singularities (seam singuralities) is also shown in the flat and open FRW-brane universe models. |
gr-qc/0109071 | Haret Rosu | H.C. Rosu, J. Torres | A Grassmann representation of the Hubble parameter | 4 pages, no figures | Mod.Phys.Lett. A16 (2001) 2359 | 10.1142/S0217732301005357 | null | gr-qc | null | The Riccati equation for the Hubble parameter H of barotropic FRW cosmologies
in conformal time for \kappa \neq 0 spatial geometries and in comoving time for
the \kappa =0 geometry, respectively, is generalized to odd Grassmannian time
parameters. We obtain a system of simple differential equations for the four
supercomponents (two of even type and two of odd type) of the Hubble superfield
function {\cal H} that is explicitly solved. The second even Hubble component
does not have an evolution governed by general relativity although there are
effects of the latter upon it
| [
{
"created": "Thu, 20 Sep 2001 02:05:25 GMT",
"version": "v1"
},
{
"created": "Tue, 2 Oct 2001 00:29:20 GMT",
"version": "v2"
},
{
"created": "Wed, 3 Oct 2001 01:03:56 GMT",
"version": "v3"
},
{
"created": "Sun, 14 Oct 2001 21:40:39 GMT",
"version": "v4"
},
{
"cre... | 2009-11-07 | [
[
"Rosu",
"H. C.",
""
],
[
"Torres",
"J.",
""
]
] | The Riccati equation for the Hubble parameter H of barotropic FRW cosmologies in conformal time for \kappa \neq 0 spatial geometries and in comoving time for the \kappa =0 geometry, respectively, is generalized to odd Grassmannian time parameters. We obtain a system of simple differential equations for the four supercomponents (two of even type and two of odd type) of the Hubble superfield function {\cal H} that is explicitly solved. The second even Hubble component does not have an evolution governed by general relativity although there are effects of the latter upon it |
2103.02519 | Peter K.F. Kuhfittig | Peter K.F. Kuhfittig | Slowly evolving noncommutative-geometry wormholes | 10 pages, no figures | Scientific Voyage, Vol. 1, No. 4 (2020) pp. 1-9 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper discusses noncommutative-geometry wormholes in the context of a
cosmological model due to Sung-Won Kim. An ansatz suggested by the
Friedmann-Lemaitre-Robertson-Walker (FLRW) model leads to the assumption that
the matter content can be divided into two parts, a cosmological part depending
only on time and a wormhole part depending only on space. These assumptions are
sufficient for deriving a complete zero-tidal force wormhole solution. The
wormhole is evolving due to the scale factor in the FLRW model; it is
restricted, however, to the curvature parameters $k=0$ and $k=-1$. Unlike
previous models, the noncommutative-geometry background affects both the
wormhole part and the cosmological part of the solution.
| [
{
"created": "Wed, 3 Mar 2021 16:45:19 GMT",
"version": "v1"
}
] | 2021-03-04 | [
[
"Kuhfittig",
"Peter K. F.",
""
]
] | This paper discusses noncommutative-geometry wormholes in the context of a cosmological model due to Sung-Won Kim. An ansatz suggested by the Friedmann-Lemaitre-Robertson-Walker (FLRW) model leads to the assumption that the matter content can be divided into two parts, a cosmological part depending only on time and a wormhole part depending only on space. These assumptions are sufficient for deriving a complete zero-tidal force wormhole solution. The wormhole is evolving due to the scale factor in the FLRW model; it is restricted, however, to the curvature parameters $k=0$ and $k=-1$. Unlike previous models, the noncommutative-geometry background affects both the wormhole part and the cosmological part of the solution. |
gr-qc/9903103 | Giulio Magli | Sanjay Jhingan and Giulio Magli | Gravitational collapse of fluid bodies and cosmic censorship: analytic
insights | 14 pages, one figure, references updated | null | null | null | gr-qc astro-ph | null | The present analytical understanding on the nature of the singularities which
form at the endstate of gravitational collapse of massive fluid bodies
("stars") is reviewed. Special emphasis is devoted to the issue of physical
reasonability of the models.
| [
{
"created": "Tue, 30 Mar 1999 14:25:40 GMT",
"version": "v1"
},
{
"created": "Wed, 31 Mar 1999 15:38:01 GMT",
"version": "v2"
},
{
"created": "Wed, 26 May 1999 10:14:07 GMT",
"version": "v3"
}
] | 2007-05-23 | [
[
"Jhingan",
"Sanjay",
""
],
[
"Magli",
"Giulio",
""
]
] | The present analytical understanding on the nature of the singularities which form at the endstate of gravitational collapse of massive fluid bodies ("stars") is reviewed. Special emphasis is devoted to the issue of physical reasonability of the models. |
1909.13687 | Cyril Pitrou | Cyril Pitrou, Thiago S. Pereira | Beyond scalar, vector and tensor harmonics in maximally symmetric
three-dimensional spaces | 39 pages, 2 figures | Phys. Rev. D 100, 123535 (2019) | 10.1103/PhysRevD.100.123535 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a comprehensive construction of scalar, vector and tensor
harmonics on maximally symmetric three-dimensional spaces. Our formalism relies
on the introduction of spin-weighted spherical harmonics and a generalized
helicity basis which, together, are ideal tools to decompose harmonics into
their radial and angular dependencies. We provide a thorough and self-contained
set of expressions and relations for these harmonics. Being general, our
formalism also allows to build harmonics of higher tensor type by recursion
among radial functions, and we collect the complete set of recursive relations
which can be used. While the formalism is readily adapted to computation of CMB
transfer functions, we also collect explicit forms of the radial harmonics
which are needed for other cosmological observables. Finally, we show that in
curved spaces, normal modes cannot be factorized into a local angular
dependence and a unit norm function encoding the orbital dependence of the
harmonics, contrary to previous statements in the literature.
| [
{
"created": "Mon, 30 Sep 2019 13:33:35 GMT",
"version": "v1"
}
] | 2019-12-25 | [
[
"Pitrou",
"Cyril",
""
],
[
"Pereira",
"Thiago S.",
""
]
] | We present a comprehensive construction of scalar, vector and tensor harmonics on maximally symmetric three-dimensional spaces. Our formalism relies on the introduction of spin-weighted spherical harmonics and a generalized helicity basis which, together, are ideal tools to decompose harmonics into their radial and angular dependencies. We provide a thorough and self-contained set of expressions and relations for these harmonics. Being general, our formalism also allows to build harmonics of higher tensor type by recursion among radial functions, and we collect the complete set of recursive relations which can be used. While the formalism is readily adapted to computation of CMB transfer functions, we also collect explicit forms of the radial harmonics which are needed for other cosmological observables. Finally, we show that in curved spaces, normal modes cannot be factorized into a local angular dependence and a unit norm function encoding the orbital dependence of the harmonics, contrary to previous statements in the literature. |
1106.5205 | Leonid Grishchuk P | L. P. Grishchuk | Cosmological Sakharov Oscillations and Quantum Mechanics of the Early
Universe | 18 pages including 6 figures, submitted to Physics-Uspekhi; v.2:
additional comparisons with existing literature, scheduled for publication in
January 2012 issue of Physics-Uspekhi; v.3: corrections to match published
version | Physics-Uspekhi 55(2), 210-216 (2012), Russian original: Uspekhi
Fiz. Nauk, 182(2), 222-229 (2012) | 10.3367/UFNe.0182.2012021.0222 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This is a brief summary of a talk delivered at the Special Session of the
Physical Sciences Division of the Russian Academy of Sciences, Moscow, 25 May
2011. The meeting was devoted to the 90-th anniversary of A. D. Sakharov. The
focus of this contribution is on the standing-wave pattern of
quantum-mechanically generated metric (gravitational field) perturbations as
the origin of subsequent Sakharov oscillations in the matter power spectrum.
Other related phenomena, particularly in the area of gravitational waves, and
their observational significance are also discussed.
| [
{
"created": "Sun, 26 Jun 2011 10:11:16 GMT",
"version": "v1"
},
{
"created": "Tue, 25 Oct 2011 14:57:05 GMT",
"version": "v2"
},
{
"created": "Thu, 17 May 2012 13:46:07 GMT",
"version": "v3"
}
] | 2012-05-18 | [
[
"Grishchuk",
"L. P.",
""
]
] | This is a brief summary of a talk delivered at the Special Session of the Physical Sciences Division of the Russian Academy of Sciences, Moscow, 25 May 2011. The meeting was devoted to the 90-th anniversary of A. D. Sakharov. The focus of this contribution is on the standing-wave pattern of quantum-mechanically generated metric (gravitational field) perturbations as the origin of subsequent Sakharov oscillations in the matter power spectrum. Other related phenomena, particularly in the area of gravitational waves, and their observational significance are also discussed. |
1807.06385 | Diego Rubiera-Garcia | Victor I. Afonso, Gonzalo J. Olmo, Emanuele Orazi, Diego
Rubiera-Garcia | Mapping nonlinear gravity into General Relativity with nonlinear
electrodynamics | 11 pages. v2: next discussions inserted, refs added; matches the
version accepted for publication in EPJC | null | 10.1140/epjc/s10052-018-6356-1 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show that families of nonlinear gravity theories formulated in a
metric-affine approach and coupled to a nonlinear theory of electrodynamics can
be mapped into General Relativity (GR) coupled to another nonlinear theory of
electrodynamics. This allows to generate solutions of the former from those of
the latter using purely algebraic transformations. This correspondence is
explicitly illustrated with the Eddington-inspired Born-Infeld theory of
gravity, for which we consider a family of nonlinear electrodynamics and show
that, under the map, preserve their algebraic structure. For the particular
case of Maxwell electrodynamics coupled to Born-Infeld gravity we find, via
this correspondence, a Born-Infeld-type nonlinear electrodynamics on the GR
side. Solving the spherically symmetric electrovacuum case for the latter, we
show how the map provides directly the right solutions for the former. This
procedure opens a new door to explore astrophysical and cosmological scenarios
in nonlinear gravity theories by exploiting the full power of the analytical
and numerical methods developed within the framework of GR.
| [
{
"created": "Tue, 17 Jul 2018 12:36:42 GMT",
"version": "v1"
},
{
"created": "Fri, 26 Oct 2018 09:38:54 GMT",
"version": "v2"
}
] | 2018-11-14 | [
[
"Afonso",
"Victor I.",
""
],
[
"Olmo",
"Gonzalo J.",
""
],
[
"Orazi",
"Emanuele",
""
],
[
"Rubiera-Garcia",
"Diego",
""
]
] | We show that families of nonlinear gravity theories formulated in a metric-affine approach and coupled to a nonlinear theory of electrodynamics can be mapped into General Relativity (GR) coupled to another nonlinear theory of electrodynamics. This allows to generate solutions of the former from those of the latter using purely algebraic transformations. This correspondence is explicitly illustrated with the Eddington-inspired Born-Infeld theory of gravity, for which we consider a family of nonlinear electrodynamics and show that, under the map, preserve their algebraic structure. For the particular case of Maxwell electrodynamics coupled to Born-Infeld gravity we find, via this correspondence, a Born-Infeld-type nonlinear electrodynamics on the GR side. Solving the spherically symmetric electrovacuum case for the latter, we show how the map provides directly the right solutions for the former. This procedure opens a new door to explore astrophysical and cosmological scenarios in nonlinear gravity theories by exploiting the full power of the analytical and numerical methods developed within the framework of GR. |
1510.05820 | Kirill Krasnov | Yannick Herfray, Kirill Krasnov and Yuri Shtanov | Anisotropic singularities in chiral modified gravity | v2: published version, 42 pages, 4 figures | Class. Quantum Grav. 33 (2016) 235001 | 10.1088/0264-9381/33/23/235001 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In four space-time dimensions, there exists a special infinite-parameter
family of chiral modified gravity theories. All these theories describe just
two propagating polarizations of the graviton. General Relativity with an
arbitrary cosmological constant is the only parity-invariant member of this
family. We review how these modified gravity theories arise within the
framework of pure-connection formulation. We introduce a new convenient
parametrisation of this family of theories by using certain set of auxiliary
fields. Modifications of General Relativity can be arranged so as to become
important in regions with large Weyl curvature, while the behaviour is
indistinguishable from GR where Weyl curvature is small. We show how the Kasner
singularity of General Relativity is resolved in a particular class of modified
gravity theories of this type, leading to solutions in which the fundamental
connection field is regular all through the space-time. There arises a new
asymptotically De Sitter region `behind' the would-be singularity, the complete
solution thus being of a bounce type.
| [
{
"created": "Tue, 20 Oct 2015 10:15:36 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Dec 2016 10:27:36 GMT",
"version": "v2"
}
] | 2018-10-26 | [
[
"Herfray",
"Yannick",
""
],
[
"Krasnov",
"Kirill",
""
],
[
"Shtanov",
"Yuri",
""
]
] | In four space-time dimensions, there exists a special infinite-parameter family of chiral modified gravity theories. All these theories describe just two propagating polarizations of the graviton. General Relativity with an arbitrary cosmological constant is the only parity-invariant member of this family. We review how these modified gravity theories arise within the framework of pure-connection formulation. We introduce a new convenient parametrisation of this family of theories by using certain set of auxiliary fields. Modifications of General Relativity can be arranged so as to become important in regions with large Weyl curvature, while the behaviour is indistinguishable from GR where Weyl curvature is small. We show how the Kasner singularity of General Relativity is resolved in a particular class of modified gravity theories of this type, leading to solutions in which the fundamental connection field is regular all through the space-time. There arises a new asymptotically De Sitter region `behind' the would-be singularity, the complete solution thus being of a bounce type. |
2005.10194 | Beatriz Elizaga Navascu\'es | Beatriz Elizaga Navascu\'es, Guillermo A. Mena Marug\'an and Santiago
Prado | Non-oscillating power spectra in Loop Quantum Cosmology | 18 pages, 1 figure | Class. Quantum Grav. 38 035001 (2021) | 10.1088/1361-6382/abc6bb | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We characterize in an analytical way the general conditions that a choice of
vacuum state for the cosmological perturbations must satisfy to lead to a power
spectrum with no scale-dependent oscillations over time. In particular, we pay
special attention to the case of cosmological backgrounds governed by effective
Loop Quantum Cosmology and in which the Einsteinian branch after the bounce
suffers a pre-inationary period of deccelerated expansion. This is the case
more often studied in the literature because of the physical interest of the
resulting predictions. In this context, we argue that non-oscillating power
spectra are optimal to gain observational access to those regimes near the
bounce where Loop Quantum Cosmology effects are non-negligible. In addition, we
show that non-oscillatory spectra can indeed be consistently obtained when the
evolution of the perturbations is ruled by the hyperbolic equations derived in
the hybrid loop quantization approach. Moreover, in the ultraviolet regime of
short wavelength scales we prove that there exists a unique asymptotic
expansion of the power spectrum that displays no scale-dependent oscillations
over time. This expansion would pick out the natural Poincar\'e and Bunch
Davies vacua in Minkowski and de Sitter spacetimes, respectively, and provides
an appealing candidate for the choice of a vacuum for the perturbations in Loop
Quantum Cosmology based on physical motivations.
| [
{
"created": "Wed, 20 May 2020 17:00:26 GMT",
"version": "v1"
},
{
"created": "Tue, 2 Feb 2021 06:32:52 GMT",
"version": "v2"
}
] | 2021-02-03 | [
[
"Navascués",
"Beatriz Elizaga",
""
],
[
"Marugán",
"Guillermo A. Mena",
""
],
[
"Prado",
"Santiago",
""
]
] | We characterize in an analytical way the general conditions that a choice of vacuum state for the cosmological perturbations must satisfy to lead to a power spectrum with no scale-dependent oscillations over time. In particular, we pay special attention to the case of cosmological backgrounds governed by effective Loop Quantum Cosmology and in which the Einsteinian branch after the bounce suffers a pre-inationary period of deccelerated expansion. This is the case more often studied in the literature because of the physical interest of the resulting predictions. In this context, we argue that non-oscillating power spectra are optimal to gain observational access to those regimes near the bounce where Loop Quantum Cosmology effects are non-negligible. In addition, we show that non-oscillatory spectra can indeed be consistently obtained when the evolution of the perturbations is ruled by the hyperbolic equations derived in the hybrid loop quantization approach. Moreover, in the ultraviolet regime of short wavelength scales we prove that there exists a unique asymptotic expansion of the power spectrum that displays no scale-dependent oscillations over time. This expansion would pick out the natural Poincar\'e and Bunch Davies vacua in Minkowski and de Sitter spacetimes, respectively, and provides an appealing candidate for the choice of a vacuum for the perturbations in Loop Quantum Cosmology based on physical motivations. |
gr-qc/0608080 | Jorma Louko | Gabor Kunstatter, Jorma Louko | Transgressing the horizons: Time operator in two-dimensional dilaton
gravity | 32 pages, 1 eps figure. v2: references and comments added | Phys.Rev.D75:024036,2007 | 10.1103/PhysRevD.75.024036 | null | gr-qc hep-th | null | We present a Dirac quantization of generic single-horizon black holes in
two-dimensional dilaton gravity. The classical theory is first partially
reduced by a spatial gauge choice under which the spatial surfaces extend from
a black or white hole singularity to a spacelike infinity. The theory is then
quantized in a metric representation, solving the quantum Hamiltonian
constraint in terms of (generalized) eigenstates of the ADM mass operator and
specifying the physical inner product by self-adjointness of a time operator
that is affinely conjugate to the ADM mass. Regularity of the time operator
across the horizon requires the operator to contain a quantum correction that
distinguishes the future and past horizons and gives rise to a quantum
correction in the hole's surface gravity. We expect a similar quantum
correction to be present in systems whose dynamics admits black hole formation
by gravitational collapse.
| [
{
"created": "Wed, 16 Aug 2006 18:09:58 GMT",
"version": "v1"
},
{
"created": "Fri, 2 Feb 2007 10:39:23 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Kunstatter",
"Gabor",
""
],
[
"Louko",
"Jorma",
""
]
] | We present a Dirac quantization of generic single-horizon black holes in two-dimensional dilaton gravity. The classical theory is first partially reduced by a spatial gauge choice under which the spatial surfaces extend from a black or white hole singularity to a spacelike infinity. The theory is then quantized in a metric representation, solving the quantum Hamiltonian constraint in terms of (generalized) eigenstates of the ADM mass operator and specifying the physical inner product by self-adjointness of a time operator that is affinely conjugate to the ADM mass. Regularity of the time operator across the horizon requires the operator to contain a quantum correction that distinguishes the future and past horizons and gives rise to a quantum correction in the hole's surface gravity. We expect a similar quantum correction to be present in systems whose dynamics admits black hole formation by gravitational collapse. |
2104.01054 | Yurii Ignat'ev | Yu.G. Ignat'ev and I.A. Kokh | Complete cosmological model based on a asymmetric scalar Higgs doublet | 30 pages, 66 figures, 52 references | Theoret. Math. Phys., 207 514 (2021) | 10.1134/S0040577921040097 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A study of a complete cosmological model based on an asymmetric scalar
doublet represented by the classical and phantom scalar Higgs fields is carried
out. At the same time, the assumption about the nonnegativity of the expansion
rate of the Universe, which in some cases contradicts the complete system of
Einstein's equations, was removed. A closed system of dynamic equations
describing the evolution of the cosmological model is formulated, and the
dependence of the topology of the Einstein - Higgs hypersurface of the
5-dimensional phase space of the dynamical system that determines the global
properties of the cosmological model on the fundamental constants of the model
is investigated. A qualitative analysis of the dynamical system of the
corresponding cosmological model is carried out, asymptotic phase trajectories
are constructed, and the results of numerical modeling are presented,
illustrating various types of behavior of the cosmological model.
| [
{
"created": "Tue, 30 Mar 2021 13:51:59 GMT",
"version": "v1"
}
] | 2021-04-05 | [
[
"Ignat'ev",
"Yu. G.",
""
],
[
"Kokh",
"I. A.",
""
]
] | A study of a complete cosmological model based on an asymmetric scalar doublet represented by the classical and phantom scalar Higgs fields is carried out. At the same time, the assumption about the nonnegativity of the expansion rate of the Universe, which in some cases contradicts the complete system of Einstein's equations, was removed. A closed system of dynamic equations describing the evolution of the cosmological model is formulated, and the dependence of the topology of the Einstein - Higgs hypersurface of the 5-dimensional phase space of the dynamical system that determines the global properties of the cosmological model on the fundamental constants of the model is investigated. A qualitative analysis of the dynamical system of the corresponding cosmological model is carried out, asymptotic phase trajectories are constructed, and the results of numerical modeling are presented, illustrating various types of behavior of the cosmological model. |
1703.00589 | Myungseok Eune | Myungseok Eune and Wontae Kim | Proper temperature of Schwarzschild AdS black hole revisited | 12 pages, 1 figure, version published in PLB | Physics Letters B 773 (2017) 57 | 10.1016/j.physletb.2017.08.009 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Unruh temperature calculated from the global embedding of the
Schwarzschild AdS spacetime into Minkowski spacetime was identified with the
local temperature measured by a free-fall observer; however, it would be
imaginary in a certain region outside the event horizon. So, the temperature
was assumed to be zero of no thermal radiation for that region. In this paper,
we revisit this issue in the exactly soluble two-dimensional Schwarzschild AdS
black hole and present an alternative resolution to this problem by using the
Tolman's procedure. However, the process is not straightforward in the sense
that one should extend the original procedure to rest upon the traceless
energy-momentum tensor in such a way that it could encompass the case of the
non-vanishing trace of energy-momentum tensor in the presence of the trace
anomaly. Consequently, we show that the free-fall temperature turns out to be
real everywhere outside the event horizon without any imaginary value, in
particular, it vanishes both at the horizon and at the asymptotic infinity.
| [
{
"created": "Thu, 2 Mar 2017 02:31:00 GMT",
"version": "v1"
},
{
"created": "Mon, 21 Aug 2017 23:15:22 GMT",
"version": "v2"
}
] | 2017-08-23 | [
[
"Eune",
"Myungseok",
""
],
[
"Kim",
"Wontae",
""
]
] | The Unruh temperature calculated from the global embedding of the Schwarzschild AdS spacetime into Minkowski spacetime was identified with the local temperature measured by a free-fall observer; however, it would be imaginary in a certain region outside the event horizon. So, the temperature was assumed to be zero of no thermal radiation for that region. In this paper, we revisit this issue in the exactly soluble two-dimensional Schwarzschild AdS black hole and present an alternative resolution to this problem by using the Tolman's procedure. However, the process is not straightforward in the sense that one should extend the original procedure to rest upon the traceless energy-momentum tensor in such a way that it could encompass the case of the non-vanishing trace of energy-momentum tensor in the presence of the trace anomaly. Consequently, we show that the free-fall temperature turns out to be real everywhere outside the event horizon without any imaginary value, in particular, it vanishes both at the horizon and at the asymptotic infinity. |
0704.3634 | Paul Lasky | Paul Lasky, Anthony Lun | Gravitational collapse of spherically symmetric plasmas in
Einstein-Maxwell spacetimes | Accepted for publication in Phys. Rev. D | Phys.Rev.D75:104010,2007 | 10.1103/PhysRevD.75.104010 | null | gr-qc | null | We utilize a recent formulation of a spherically symmetric spacetime endowed
with a general decomposition of the energy momentum tensor [Phys. Rev. D, 75,
024031 (2007)] to derive equations governing spherically symmetric
distributions of electromagnetic matter. We show the system reduces to the
Reissner-Nordstrom spacetime in general, spherically symmetric coordinates in
the vacuum limit. Furthermore, we show reduction to the charged Vaidya
spacetime in non-null coordinates when certain equations of states are chosen.
A model of gravitational collapse is discussed whereby a charged fluid resides
within a boundary of finite radial extent on the initial hypersurface, and is
allowed to radiate charged particles. Our formalism allows for the discussion
of all regions in this model without the need for complicated matching schemes
at the interfaces between successive regions. As further examples we consider
the collapse of a thin shell of charged matter onto a Reissner-Nordstrom black
hole. Finally, we reduce the entire system of equations to the static case such
that we have the equations for hydrostatic equilibrium of a charged fluid.
| [
{
"created": "Thu, 26 Apr 2007 22:15:13 GMT",
"version": "v1"
},
{
"created": "Mon, 7 May 2007 01:02:23 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Lasky",
"Paul",
""
],
[
"Lun",
"Anthony",
""
]
] | We utilize a recent formulation of a spherically symmetric spacetime endowed with a general decomposition of the energy momentum tensor [Phys. Rev. D, 75, 024031 (2007)] to derive equations governing spherically symmetric distributions of electromagnetic matter. We show the system reduces to the Reissner-Nordstrom spacetime in general, spherically symmetric coordinates in the vacuum limit. Furthermore, we show reduction to the charged Vaidya spacetime in non-null coordinates when certain equations of states are chosen. A model of gravitational collapse is discussed whereby a charged fluid resides within a boundary of finite radial extent on the initial hypersurface, and is allowed to radiate charged particles. Our formalism allows for the discussion of all regions in this model without the need for complicated matching schemes at the interfaces between successive regions. As further examples we consider the collapse of a thin shell of charged matter onto a Reissner-Nordstrom black hole. Finally, we reduce the entire system of equations to the static case such that we have the equations for hydrostatic equilibrium of a charged fluid. |
1303.3225 | Piotr Jaranowski | Piotr Jaranowski and Gerhard Sch\"afer | Dimensional regularization of local singularities in the 4th
post-Newtonian two-point-mass Hamiltonian | 6 pages, 2 figures | null | 10.1103/PhysRevD.87.081503 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The article delivers the only still unknown coefficient in the 4th
post-Newtonian energy expression for binary point masses on circular orbits as
function of orbital angular frequency. Apart from a single coefficient, which
is known solely numerically, all the coefficients are given as exact numbers.
The shown Hamiltonian is presented in the center-of-mass frame and out of its
57 coefficients 51 are given fully explicitly. Those coefficients are six
coefficients more than previously achieved [Jaranowski/Sch\"afer, Phys. Rev. D
86, 061503(R) (2012)]. The local divergences in the point-mass model are
uniquely controlled by the method of dimensional regularization. As
application, the last stable circular orbit is determined as function of the
symmetric-mass-ratio parameter.
| [
{
"created": "Wed, 13 Mar 2013 17:43:01 GMT",
"version": "v1"
}
] | 2013-05-01 | [
[
"Jaranowski",
"Piotr",
""
],
[
"Schäfer",
"Gerhard",
""
]
] | The article delivers the only still unknown coefficient in the 4th post-Newtonian energy expression for binary point masses on circular orbits as function of orbital angular frequency. Apart from a single coefficient, which is known solely numerically, all the coefficients are given as exact numbers. The shown Hamiltonian is presented in the center-of-mass frame and out of its 57 coefficients 51 are given fully explicitly. Those coefficients are six coefficients more than previously achieved [Jaranowski/Sch\"afer, Phys. Rev. D 86, 061503(R) (2012)]. The local divergences in the point-mass model are uniquely controlled by the method of dimensional regularization. As application, the last stable circular orbit is determined as function of the symmetric-mass-ratio parameter. |
0705.4036 | Alexey Toporensky | A. Toporensky, P. Tretyakov | Certain aspects of regularity in scalar field cosmological dynamics | 15 pages with 4 figures; typos corrected, final version to appear in
Regular and Chaotic Dynamics | null | 10.1134/S1560354707040016 | null | gr-qc nlin.CD | null | We consider dynamics of the FRW Universe with a scalar field. Using
Maupertuis principle we find a curvature of geodesics flow and show that zones
of positive curvature exist for all considered types of scalar field potential.
Usually, phase space of systems with the positive curvature contains islands of
regular motion. We find these islands numerically for shallow scalar field
potentials. It is shown also that beyond the physical domain the islands of
regularity exist for quadratic potentials as well.
| [
{
"created": "Mon, 28 May 2007 12:27:24 GMT",
"version": "v1"
},
{
"created": "Tue, 5 Jun 2007 16:14:00 GMT",
"version": "v2"
},
{
"created": "Sun, 15 Jul 2007 20:48:17 GMT",
"version": "v3"
}
] | 2009-11-13 | [
[
"Toporensky",
"A.",
""
],
[
"Tretyakov",
"P.",
""
]
] | We consider dynamics of the FRW Universe with a scalar field. Using Maupertuis principle we find a curvature of geodesics flow and show that zones of positive curvature exist for all considered types of scalar field potential. Usually, phase space of systems with the positive curvature contains islands of regular motion. We find these islands numerically for shallow scalar field potentials. It is shown also that beyond the physical domain the islands of regularity exist for quadratic potentials as well. |
gr-qc/0207029 | Sijie Gao | Sijie Gao | Late-time particle creation from gravitational collapse to an extremal
Reissner-Nordstrom black hole | revised version, 25 pages, 2 figures | Phys.Rev. D68 (2003) 044028 | 10.1103/PhysRevD.68.044028 | null | gr-qc | null | We investigate the late time behavior of particle creation from an extremal
Reissner-Nordstrom (RN) black hole formed by gravitational collapse. We
calculate explicitly the particle flux associated with a massless scalar field
at late times after the collapse. Our result shows that the expected number of
particles in any wave packet spontaneously created from the ``in'' vacuum state
approaches zero faster than any inverse power of time. This result confirms the
traditional belief that extremal black holes do not emit particles. We also
calculate the expectation value of the stress energy tensor in a 1+1 RN black
hole and show that it also drops to zero at late times. Some comments on
previous work by other authors are provided.
| [
{
"created": "Thu, 4 Jul 2002 16:25:42 GMT",
"version": "v1"
},
{
"created": "Wed, 24 Sep 2003 17:08:27 GMT",
"version": "v2"
}
] | 2009-11-07 | [
[
"Gao",
"Sijie",
""
]
] | We investigate the late time behavior of particle creation from an extremal Reissner-Nordstrom (RN) black hole formed by gravitational collapse. We calculate explicitly the particle flux associated with a massless scalar field at late times after the collapse. Our result shows that the expected number of particles in any wave packet spontaneously created from the ``in'' vacuum state approaches zero faster than any inverse power of time. This result confirms the traditional belief that extremal black holes do not emit particles. We also calculate the expectation value of the stress energy tensor in a 1+1 RN black hole and show that it also drops to zero at late times. Some comments on previous work by other authors are provided. |
1909.11962 | Ben David Normann Mr. | Ben David Normann, Sigbj{\o}rn Hervik | Approaching Wonderland | 42 pages, 6 figures | Class. Quantum Grav. 37 (2020) 085002 | 10.1088/1361-6382/ab719b | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Continuing previous work, we show the existence of stable, anisotropic future
attractors in Bianchi invariant sets with a $p$-form field ($p\,\in\,\{1,3\}$)
and a perfect fluid. In particular, we consider the not previously investigated
Bianchi invariant sets $\mathcal{B}$(II), $\mathcal{B}$(IV),
$\mathcal{B}$(VII$_0$) and $\mathcal{B}$(VII$_{h})$ and examine their
asymptotic behaviour. We find that the isolated equilibrium set Wonderland is a
future attractor on all of its existence ($2/3<\,\gamma\,<2$) in all these sets
except in $\mathcal{B}$(II), where the peculiar equilibrium sets Edge and Rope
show up, taking over the stability for certain values of $\gamma$. In addition,
in $\mathcal{B}$(IV) and $\mathcal{B}$(VII$_h$) plane gravitational wave
solutions (with a non-zero $p$-form) serve as attractors whenever
$2/3<\,\gamma\,<2$.
| [
{
"created": "Thu, 26 Sep 2019 07:54:47 GMT",
"version": "v1"
},
{
"created": "Tue, 31 Mar 2020 11:58:25 GMT",
"version": "v2"
}
] | 2020-04-01 | [
[
"Normann",
"Ben David",
""
],
[
"Hervik",
"Sigbjørn",
""
]
] | Continuing previous work, we show the existence of stable, anisotropic future attractors in Bianchi invariant sets with a $p$-form field ($p\,\in\,\{1,3\}$) and a perfect fluid. In particular, we consider the not previously investigated Bianchi invariant sets $\mathcal{B}$(II), $\mathcal{B}$(IV), $\mathcal{B}$(VII$_0$) and $\mathcal{B}$(VII$_{h})$ and examine their asymptotic behaviour. We find that the isolated equilibrium set Wonderland is a future attractor on all of its existence ($2/3<\,\gamma\,<2$) in all these sets except in $\mathcal{B}$(II), where the peculiar equilibrium sets Edge and Rope show up, taking over the stability for certain values of $\gamma$. In addition, in $\mathcal{B}$(IV) and $\mathcal{B}$(VII$_h$) plane gravitational wave solutions (with a non-zero $p$-form) serve as attractors whenever $2/3<\,\gamma\,<2$. |
1003.2617 | John Klauder | John R. Klauder | An Affinity for Affine Quantum Gravity | 14 pages, contribution to the proceedings of the conference "Gauge
Fields. Yesterday, Today, and Tomorrow", Moscow, Russia, Jan. 19-24, 2010 | null | null | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The main principle of affine quantum gravity is the strict positivity of the
matrix \{\hat g_{ab}(x)\} composed of the spatial components of the local
metric operator. Canonical commutation relations are incompatible with this
principle, and they can be replaced by noncanonical, affine commutation
relations. Due to the partial second-class nature of the quantum gravitational
constraints, it is advantageous to use the projection operator method, which
treats all quantum constraints on an equal footing. Using this method,
enforcement of regularized versions of the gravitational constraint operators
is formulated quite naturally as a novel and relatively well-defined functional
integral involving only the same set of variables that appears in the usual
classical formulation. Although perturbatively nonrenormalizable, gravity may
possibly be understood nonperturbatively from a hard-core perspective that has
proved valuable for specialized models.
| [
{
"created": "Fri, 12 Mar 2010 20:48:00 GMT",
"version": "v1"
}
] | 2010-03-15 | [
[
"Klauder",
"John R.",
""
]
] | The main principle of affine quantum gravity is the strict positivity of the matrix \{\hat g_{ab}(x)\} composed of the spatial components of the local metric operator. Canonical commutation relations are incompatible with this principle, and they can be replaced by noncanonical, affine commutation relations. Due to the partial second-class nature of the quantum gravitational constraints, it is advantageous to use the projection operator method, which treats all quantum constraints on an equal footing. Using this method, enforcement of regularized versions of the gravitational constraint operators is formulated quite naturally as a novel and relatively well-defined functional integral involving only the same set of variables that appears in the usual classical formulation. Although perturbatively nonrenormalizable, gravity may possibly be understood nonperturbatively from a hard-core perspective that has proved valuable for specialized models. |
2309.09767 | Gabriele Barca | Gabriele Barca, Giovanni Montani | Non-Singular Gravitational Collapse through Modified Heisenberg Algebra | 14 pages, 4 figures. New upload to match published version | Eur. Phys. J. C 84, 261 (2024) | 10.1140/epjc/s10052-024-12564-5 | null | gr-qc astro-ph.SR hep-th | http://creativecommons.org/licenses/by/4.0/ | We study the effects of cut-off physics, in the form of a modified algebra
inspired by Polymer Quantum Mechanics and by the Generalized Uncertainty
Principle representation, on the collapse of a spherical dust cloud. We analyze
both the Newtonian formulation, originally developed by Hunter, and the general
relativistic formulation, that is the Oppenheimer-Snyder model; in both
frameworks we find that the collapse is stabilized to an asymptotically static
state above the horizon, and the singularity is removed. In the Newtonian case,
by requiring the Newtonian approximation to be valid, we find lower bounds of
the order of unity (in Planck units) for the deformation parameter of the
modified algebra. We then study the behaviour of small perturbations on the
non-singular collapsing backgrounds, and find that for certain range of the
parameters (the polytropic index for the Newtonian case and the sound velocity
in the relativistic setting) the collapse is stable to perturbations of all
scales, and the non-singular super-Schwarzschild configurations have physical
meaning.
| [
{
"created": "Mon, 18 Sep 2023 13:48:28 GMT",
"version": "v1"
},
{
"created": "Wed, 13 Mar 2024 13:22:58 GMT",
"version": "v2"
}
] | 2024-03-14 | [
[
"Barca",
"Gabriele",
""
],
[
"Montani",
"Giovanni",
""
]
] | We study the effects of cut-off physics, in the form of a modified algebra inspired by Polymer Quantum Mechanics and by the Generalized Uncertainty Principle representation, on the collapse of a spherical dust cloud. We analyze both the Newtonian formulation, originally developed by Hunter, and the general relativistic formulation, that is the Oppenheimer-Snyder model; in both frameworks we find that the collapse is stabilized to an asymptotically static state above the horizon, and the singularity is removed. In the Newtonian case, by requiring the Newtonian approximation to be valid, we find lower bounds of the order of unity (in Planck units) for the deformation parameter of the modified algebra. We then study the behaviour of small perturbations on the non-singular collapsing backgrounds, and find that for certain range of the parameters (the polytropic index for the Newtonian case and the sound velocity in the relativistic setting) the collapse is stable to perturbations of all scales, and the non-singular super-Schwarzschild configurations have physical meaning. |
1606.00811 | Mengjie Wang | Mengjie Wang | Quantum and classical aspects of scalar and vector fields around black
holes | PhD thesis, 195 pages, defended in February 2016. Based on the
publications arXiv:1110.2485, arXiv:1212.2197, arXiv:1403.5160,
arXiv:1406.3536, arXiv:1510.04713, arXiv:1512.02262 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This thesis presents recent studies on test scalar and vector fields around
black holes. It is separated in two parts according to the asymptotic
properties of the spacetime under study. In the first part, we investigate
scalar and Proca fields on an asymptotically flat background. For the Proca
field, we obtain a complete set of equations of motion in higher dimensional
spherically symmetric backgrounds. These equations are solved numerically, both
to compute Hawking radiation spectra and quasi-bound states. In the former
case, we carry out a precise study of the longitudinal degrees of freedom
induced by the field mass. This can be used to improve the model in the black
hole event generators currently used at the Large Hadron Collider. Regarding
quasi-bound states, we find arbitrarily long lived modes for a charged Proca
field, as well as for a charged scalar field, in a Reissner-Nordstr\"om black
hole. The second part of this thesis presents research on superradiant
instabilities of scalar and Maxwell fields on an asymptotically anti-de Sitter
background. For the scalar case, we introduce a charge coupling between the
field and the background, and show that superradiant instabilities do exist for
all $\ell$ modes, in higher dimensions. For the Maxwell case, we first propose
a general prescription to impose boundary conditions on the Kerr-anti-de Sitter
spacetime, and obtain two Robin boundary conditions. Then these two conditions
are implemented to study superradiant unstable modes and vector clouds. In
particular, we find that the new branch of quasinormal modes may be unstable in
a larger parameter space. Furthermore, the existence of vector clouds indicates
that one may find a vector hairy black hole solution for the
Einstein-Maxwell-anti-de Sitter system at the nonlinear level, which implies
that, in such system, the Kerr-Newman-anti-de Sitter black hole is not a unique
solution.
| [
{
"created": "Thu, 2 Jun 2016 19:10:32 GMT",
"version": "v1"
}
] | 2016-06-03 | [
[
"Wang",
"Mengjie",
""
]
] | This thesis presents recent studies on test scalar and vector fields around black holes. It is separated in two parts according to the asymptotic properties of the spacetime under study. In the first part, we investigate scalar and Proca fields on an asymptotically flat background. For the Proca field, we obtain a complete set of equations of motion in higher dimensional spherically symmetric backgrounds. These equations are solved numerically, both to compute Hawking radiation spectra and quasi-bound states. In the former case, we carry out a precise study of the longitudinal degrees of freedom induced by the field mass. This can be used to improve the model in the black hole event generators currently used at the Large Hadron Collider. Regarding quasi-bound states, we find arbitrarily long lived modes for a charged Proca field, as well as for a charged scalar field, in a Reissner-Nordstr\"om black hole. The second part of this thesis presents research on superradiant instabilities of scalar and Maxwell fields on an asymptotically anti-de Sitter background. For the scalar case, we introduce a charge coupling between the field and the background, and show that superradiant instabilities do exist for all $\ell$ modes, in higher dimensions. For the Maxwell case, we first propose a general prescription to impose boundary conditions on the Kerr-anti-de Sitter spacetime, and obtain two Robin boundary conditions. Then these two conditions are implemented to study superradiant unstable modes and vector clouds. In particular, we find that the new branch of quasinormal modes may be unstable in a larger parameter space. Furthermore, the existence of vector clouds indicates that one may find a vector hairy black hole solution for the Einstein-Maxwell-anti-de Sitter system at the nonlinear level, which implies that, in such system, the Kerr-Newman-anti-de Sitter black hole is not a unique solution. |
1103.0712 | Jacques Smulevici | Gustav Holzegel, Jacques Smulevici | Self-gravitating Klein-Gordon fields in asymptotically Anti-de-Sitter
spacetimes | 50 pages, v2: minor changes, to appear in Annales Henri Poincar\'e | null | 10.1007/s00023-011-0146-8 | null | gr-qc math.AP math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We initiate the study of the spherically symmetric Einstein-Klein-Gordon
system in the presence of a negative cosmological constant, a model appearing
frequently in the context of high-energy physics. Due to the lack of global
hyperbolicity of the solutions, the natural formulation of dynamics is that of
an initial boundary value problem, with boundary conditions imposed at null
infinity. We prove a local well-posedness statement for this system, with the
time of existence of the solutions depending only on an invariant H^2-type norm
measuring the size of the Klein-Gordon field on the initial data. The proof
requires the introduction of a renormalized system of equations and relies
crucially on r-weighted estimates for the wave equation on asymptotically AdS
spacetimes. The results provide the basis for our companion paper establishing
the global asymptotic stability of Schwarzschild-Anti-de-Sitter within this
system.
| [
{
"created": "Thu, 3 Mar 2011 15:19:30 GMT",
"version": "v1"
},
{
"created": "Mon, 31 Oct 2011 16:21:21 GMT",
"version": "v2"
}
] | 2015-05-27 | [
[
"Holzegel",
"Gustav",
""
],
[
"Smulevici",
"Jacques",
""
]
] | We initiate the study of the spherically symmetric Einstein-Klein-Gordon system in the presence of a negative cosmological constant, a model appearing frequently in the context of high-energy physics. Due to the lack of global hyperbolicity of the solutions, the natural formulation of dynamics is that of an initial boundary value problem, with boundary conditions imposed at null infinity. We prove a local well-posedness statement for this system, with the time of existence of the solutions depending only on an invariant H^2-type norm measuring the size of the Klein-Gordon field on the initial data. The proof requires the introduction of a renormalized system of equations and relies crucially on r-weighted estimates for the wave equation on asymptotically AdS spacetimes. The results provide the basis for our companion paper establishing the global asymptotic stability of Schwarzschild-Anti-de-Sitter within this system. |
gr-qc/0205045 | Tsvi Piran | Tsvi Piran | Gamma-Ray Bursts - a Primer For Relativists | Review talk given at GR16 | null | 10.1142/9789812776556_0013 | null | gr-qc | null | Gamma-Ray Bursts (GRBs) - short bursts of 100-1MeV photons arriving from
random directions in the sky are probably the most relativistic objects
discovered so far. Still, somehow they did not attract the attention of the
relativistic community. In this short review I discuss briefly GRB observations
and show that they lead us to the fireball model - GRBs involve macroscopic
relativistic motion with Lorentz factors of a few hundred or more. I show that
GRB sources involve, most likely, new born black holes, and their progenitors
are Supernovae or neutron star mergers. I show that both GRB progenitors and
the process of GRB itself produce gravitational radiation and I consider the
possibility of detecting this emission. Finally I show that GRBs could serve as
cosmological indicators that could teach us about the high redshift ($z \approx
5-15$) dark ages of the universe.
| [
{
"created": "Sun, 12 May 2002 08:04:11 GMT",
"version": "v1"
}
] | 2017-08-23 | [
[
"Piran",
"Tsvi",
""
]
] | Gamma-Ray Bursts (GRBs) - short bursts of 100-1MeV photons arriving from random directions in the sky are probably the most relativistic objects discovered so far. Still, somehow they did not attract the attention of the relativistic community. In this short review I discuss briefly GRB observations and show that they lead us to the fireball model - GRBs involve macroscopic relativistic motion with Lorentz factors of a few hundred or more. I show that GRB sources involve, most likely, new born black holes, and their progenitors are Supernovae or neutron star mergers. I show that both GRB progenitors and the process of GRB itself produce gravitational radiation and I consider the possibility of detecting this emission. Finally I show that GRBs could serve as cosmological indicators that could teach us about the high redshift ($z \approx 5-15$) dark ages of the universe. |
gr-qc/0409043 | Christopher J. Fewster | C.J. Fewster | Comments on "Counter example to the quantum inequality" | 5pp REVTeX | null | null | null | gr-qc | null | In a recent preprint, Krasnikov has claimed that to show that quantum energy
inequalities (QEIs) are violated in curved spacetime situations, by considering
the example of a free massless scalar field in two-dimensional de Sitter space.
We show that this claim is incorrect, and based on misunderstandings of the
nature of QEIs. We also prove, in general two-dimensional spacetimes, that flat
spacetime QEIs give a good approximation to the curved spacetime results on
sampling timescales short in comparison with natural geometric scales.
| [
{
"created": "Fri, 10 Sep 2004 11:27:22 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Fewster",
"C. J.",
""
]
] | In a recent preprint, Krasnikov has claimed that to show that quantum energy inequalities (QEIs) are violated in curved spacetime situations, by considering the example of a free massless scalar field in two-dimensional de Sitter space. We show that this claim is incorrect, and based on misunderstandings of the nature of QEIs. We also prove, in general two-dimensional spacetimes, that flat spacetime QEIs give a good approximation to the curved spacetime results on sampling timescales short in comparison with natural geometric scales. |
1705.05426 | Fumika Suzuki | Fumika Suzuki and Friedemann Queisser | Quantum tunneling of composite object coupled with quantized radiation
field | 19 pages, 6 figures, version to appear in Class. Quantum Grav | Class. Quantum Grav. 36, 055009 (2019) | 10.1088/1361-6382/ab019c | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study quantum tunneling of a composite object, which has a dipole or
quadrupole moment coupled with quantized (photon or gravitational) radiation
field, through a {\delta} potential barrier. The dipole or quadrupole moment is
represented by an oscillator in the relative coordinate of two constituent
particles of the object. The center of mass degrees of freedom of the object is
not directly coupled with the radiation field. However, we show that, for the
object with the oscillator in the excited state, dissipation caused by the
radiation field can suppress its quantum tunneling rate in the center of mass
degrees of freedom. In addition, when the initial energy of its center of mass
motion is similar to that of the excited state of the oscillator, a spatial
superposition state of the object prepared by the barrier can decohere due to
the radiation field. The main purpose of this article is to investigate how two
different interplays (i) among the center of mass, the relative coordinate
degrees of freedom and the potential barrier, and (ii) between the relative
coordinate degrees of freedom and the radiation field, can affect the quantum
tunneling and the creation of the spatial superposition state of the object.
Our toy model can give insight into tests of quantum tunneling and quantum
superposition of atoms or molecules with its dipole or quadrupole moment
coupled with the radiation field.
| [
{
"created": "Mon, 15 May 2017 19:57:26 GMT",
"version": "v1"
},
{
"created": "Sat, 24 Feb 2018 22:59:06 GMT",
"version": "v2"
},
{
"created": "Thu, 24 Jan 2019 20:52:51 GMT",
"version": "v3"
}
] | 2019-02-12 | [
[
"Suzuki",
"Fumika",
""
],
[
"Queisser",
"Friedemann",
""
]
] | We study quantum tunneling of a composite object, which has a dipole or quadrupole moment coupled with quantized (photon or gravitational) radiation field, through a {\delta} potential barrier. The dipole or quadrupole moment is represented by an oscillator in the relative coordinate of two constituent particles of the object. The center of mass degrees of freedom of the object is not directly coupled with the radiation field. However, we show that, for the object with the oscillator in the excited state, dissipation caused by the radiation field can suppress its quantum tunneling rate in the center of mass degrees of freedom. In addition, when the initial energy of its center of mass motion is similar to that of the excited state of the oscillator, a spatial superposition state of the object prepared by the barrier can decohere due to the radiation field. The main purpose of this article is to investigate how two different interplays (i) among the center of mass, the relative coordinate degrees of freedom and the potential barrier, and (ii) between the relative coordinate degrees of freedom and the radiation field, can affect the quantum tunneling and the creation of the spatial superposition state of the object. Our toy model can give insight into tests of quantum tunneling and quantum superposition of atoms or molecules with its dipole or quadrupole moment coupled with the radiation field. |
1501.05523 | Jibril Ben Achour | Jibril Ben Achour, Karim Noui | Analytic continuation of real Loop Quantum Gravity : Lessons from black
hole thermodynamics | 8 pages, 1 figure, Proceedings of Frontiers of Fundamental Physics
2014 - Proceedings of Science (PoS) | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This contribution is devoted to summarize the recent results obtained in the
construction of an "analytic continuation" of Loop Quantum Gravity (LQG). By
this, we mean that we construct analytic continuation of physical quantities in
LQG from real values of the Barbero-Immirzi parameter $\gamma$ to the purely
imaginary value $\gamma = \pm i$. This should allow us to define a quantization
of gravity with self-dual Ashtekar variables. We first realized in [1] that
this procedure, when applied to compute the entropy of a spherical black hole
in LQG for $\gamma=\pm i$, allows to reproduce exactly the Bekenstein-Hawking
area law at the semi-classical limit. The rigorous construction of the analytic
continuation of spherical black hole entropy has been done in [2]. Here, we
start with a review of the main steps of this construction: we recall that our
prescription turns out to be unique (under natural assumptions) and leads to
the right semi-classical limit with its logarithmic quantum corrections.
Furthermore, the discrete and $\gamma$-dependent area spectrum of the black
hole horizon becomes continuous and obviously $\gamma$-independent. Then, we
review how this analytic continuation could be interpreted in terms of an
analytic continuation from the compact gauge group $SU(2)$ to the non-compact
gauge group $SU(1,1)$ relying on an analysis of three dimensional quantum
gravity.
| [
{
"created": "Thu, 22 Jan 2015 15:03:11 GMT",
"version": "v1"
}
] | 2015-01-23 | [
[
"Achour",
"Jibril Ben",
""
],
[
"Noui",
"Karim",
""
]
] | This contribution is devoted to summarize the recent results obtained in the construction of an "analytic continuation" of Loop Quantum Gravity (LQG). By this, we mean that we construct analytic continuation of physical quantities in LQG from real values of the Barbero-Immirzi parameter $\gamma$ to the purely imaginary value $\gamma = \pm i$. This should allow us to define a quantization of gravity with self-dual Ashtekar variables. We first realized in [1] that this procedure, when applied to compute the entropy of a spherical black hole in LQG for $\gamma=\pm i$, allows to reproduce exactly the Bekenstein-Hawking area law at the semi-classical limit. The rigorous construction of the analytic continuation of spherical black hole entropy has been done in [2]. Here, we start with a review of the main steps of this construction: we recall that our prescription turns out to be unique (under natural assumptions) and leads to the right semi-classical limit with its logarithmic quantum corrections. Furthermore, the discrete and $\gamma$-dependent area spectrum of the black hole horizon becomes continuous and obviously $\gamma$-independent. Then, we review how this analytic continuation could be interpreted in terms of an analytic continuation from the compact gauge group $SU(2)$ to the non-compact gauge group $SU(1,1)$ relying on an analysis of three dimensional quantum gravity. |
1302.6407 | Puxun Wu | Kaituo Zhang, Puxun Wu, Hongwei Yu | Oscillating universe in massive gravity | 36 pages, 30 figures, accepted for publication in PRD. Two references
added | Physical Review D 87, 063513 (2013) | 10.1103/PhysRevD.87.063513 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Massive gravity is a modified theory of general relativity. In this paper, we
study, using a method in which the scale factor changes as a particle in a
"potential", all possible cosmic evolutions in a ghost-free massive gravity. We
find that there exists, in certain circumstances, an oscillating universe or a
bouncing one. If the universe starts at the oscillating region, it may undergo
a number of oscillations before it quantum mechanically tunnels to the bounce
point and then expand forever. But going back to the singularity from the
oscillating region is physically not allowed. So, the big bang singularity can
be successfully resolved. At the same time, we also find that there exists a
stable Einstein static state in some cases. However, the universe can not stay
at this stable state past-eternally since it is allowed to quantum mechanically
tunnel to a big-bang-to-big-crunch region and end with a big crunch. Thus, a
stable Einstein static state universe can not be used to avoid the big bang
singularity in massive gravity.
| [
{
"created": "Tue, 26 Feb 2013 11:52:46 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Mar 2013 11:51:59 GMT",
"version": "v2"
}
] | 2013-03-21 | [
[
"Zhang",
"Kaituo",
""
],
[
"Wu",
"Puxun",
""
],
[
"Yu",
"Hongwei",
""
]
] | Massive gravity is a modified theory of general relativity. In this paper, we study, using a method in which the scale factor changes as a particle in a "potential", all possible cosmic evolutions in a ghost-free massive gravity. We find that there exists, in certain circumstances, an oscillating universe or a bouncing one. If the universe starts at the oscillating region, it may undergo a number of oscillations before it quantum mechanically tunnels to the bounce point and then expand forever. But going back to the singularity from the oscillating region is physically not allowed. So, the big bang singularity can be successfully resolved. At the same time, we also find that there exists a stable Einstein static state in some cases. However, the universe can not stay at this stable state past-eternally since it is allowed to quantum mechanically tunnel to a big-bang-to-big-crunch region and end with a big crunch. Thus, a stable Einstein static state universe can not be used to avoid the big bang singularity in massive gravity. |
1609.05183 | Kayll Lake | Dmitri Lebedev and Kayll Lake | Relativistic Aberration and the Cosmological Constant in Gravitational
Lensing I: Introduction | revtex with 4 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An analysis of null geodesics in Schwarzschild de Sitter space is presented
with special attention to their global `bending angles', local measurable
angles, and the involvement of the cosmological constant. We make use of a
general technique which allows for finding observable intersection angles of
null trajectories analytically. A general relativistic aberration relationship
is established as one of its applications. The question of whether or not the
cosmological constant, $\Lambda$, contributes to orbits of light and to related
observable quantities is addressed in detail. We also discuss the ongoing
debate on this issue and respond to some recent papers on the topic. The
dependence of measurable quantities on the motion of observers is stressed
throughout. Exact formulas for measurable intersection angles, as well as
gravitational lens equations for observers in the Schwarzschild de Sitter
background are provided.
| [
{
"created": "Fri, 16 Sep 2016 19:16:52 GMT",
"version": "v1"
}
] | 2016-09-19 | [
[
"Lebedev",
"Dmitri",
""
],
[
"Lake",
"Kayll",
""
]
] | An analysis of null geodesics in Schwarzschild de Sitter space is presented with special attention to their global `bending angles', local measurable angles, and the involvement of the cosmological constant. We make use of a general technique which allows for finding observable intersection angles of null trajectories analytically. A general relativistic aberration relationship is established as one of its applications. The question of whether or not the cosmological constant, $\Lambda$, contributes to orbits of light and to related observable quantities is addressed in detail. We also discuss the ongoing debate on this issue and respond to some recent papers on the topic. The dependence of measurable quantities on the motion of observers is stressed throughout. Exact formulas for measurable intersection angles, as well as gravitational lens equations for observers in the Schwarzschild de Sitter background are provided. |
1105.1803 | Alexander Goltsev | Natalia Gorobey and Alexander Lukyanenko | On the Quantum Creation of Matter in the Expanding Universe | 4 pages | null | null | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Quantum Action Principle which has been used as a ground for a probabilistic
interpretation of one-particle relativistic quantum mechanics \cite{GLL} is
applied to quantum cosmology. The quantum creation of matter in a
minisuperspace model with one homogeneous scalar field is considered. The
initial state of the universe is defined as a stationary ground state of the
Hamiltonian with the Euclidean signature in which the mean value of the
universe radius is equal to the Plank length and the number of the scalar field
quanta is equal zero. We interpret the change of the signature as the universe
"birth". From this moment of time the dynamics of the scale factor is
considered as classical. The real phase of the amplitude of the creation
process is taken as a quantum action. The balance between matter and
gravitation energies in the creation process is fulfilled by the condition of
the stationarity of the quantum action with respect to the internal time of the
universe.
| [
{
"created": "Mon, 9 May 2011 21:55:12 GMT",
"version": "v1"
}
] | 2011-05-11 | [
[
"Gorobey",
"Natalia",
""
],
[
"Lukyanenko",
"Alexander",
""
]
] | Quantum Action Principle which has been used as a ground for a probabilistic interpretation of one-particle relativistic quantum mechanics \cite{GLL} is applied to quantum cosmology. The quantum creation of matter in a minisuperspace model with one homogeneous scalar field is considered. The initial state of the universe is defined as a stationary ground state of the Hamiltonian with the Euclidean signature in which the mean value of the universe radius is equal to the Plank length and the number of the scalar field quanta is equal zero. We interpret the change of the signature as the universe "birth". From this moment of time the dynamics of the scale factor is considered as classical. The real phase of the amplitude of the creation process is taken as a quantum action. The balance between matter and gravitation energies in the creation process is fulfilled by the condition of the stationarity of the quantum action with respect to the internal time of the universe. |
gr-qc/0403050 | Alexander Poltorak | Alexander Poltorak | Towards a Covariant Theory of Gravitation | 6 pages, LaTeX, GR9 Abstract (1980) | 9th International Conference on General Relativity and
Gravitation, Abstracts of Contributed Papers, Jena, GDR, 1980, v.2, p.516 | null | null | gr-qc | null | A covariant reformulation of General Relativity is briefly considered from
three points of view: geometrodynamics, Lagrange-Euler field theory, and gauge
field theory. From a geometrodynamics perspective, a definition of the
reference frame as a differential manifold with an affine connection results in
separation of the respective contributions of inertial and gravitational fields
represented by the affine connection and the tensor of nonmetricity within the
Levi-Civita connection of GR. Resulting decomposition of the Einstein curvature
tensor into affine and nonmetric parts allows to recast Einstein's field
equations in a form invariant with respect to the choice of a reference frame
wherein the gravity is described by nonmetricity of space-time . A covariant
Lagrangian is proposed leading to the same field equation. All three approaches
ultimately lead to the same fully covariant theory of gravitation with a
covariant tensor of energy-momentum of the gravitational field and differential
and integral conservation laws. The role of the frames of reference, as
distinguished from coordinate systems, is discussed.
| [
{
"created": "Fri, 12 Mar 2004 03:09:46 GMT",
"version": "v1"
},
{
"created": "Fri, 12 Mar 2004 22:24:24 GMT",
"version": "v2"
},
{
"created": "Wed, 24 Mar 2004 22:28:19 GMT",
"version": "v3"
}
] | 2007-05-23 | [
[
"Poltorak",
"Alexander",
""
]
] | A covariant reformulation of General Relativity is briefly considered from three points of view: geometrodynamics, Lagrange-Euler field theory, and gauge field theory. From a geometrodynamics perspective, a definition of the reference frame as a differential manifold with an affine connection results in separation of the respective contributions of inertial and gravitational fields represented by the affine connection and the tensor of nonmetricity within the Levi-Civita connection of GR. Resulting decomposition of the Einstein curvature tensor into affine and nonmetric parts allows to recast Einstein's field equations in a form invariant with respect to the choice of a reference frame wherein the gravity is described by nonmetricity of space-time . A covariant Lagrangian is proposed leading to the same field equation. All three approaches ultimately lead to the same fully covariant theory of gravitation with a covariant tensor of energy-momentum of the gravitational field and differential and integral conservation laws. The role of the frames of reference, as distinguished from coordinate systems, is discussed. |
1901.00002 | Iver Brevik | Iver Brevik and Mubasher Jamil | Black Holes in the Turbulent Phase of Viscous Rip Cosmology | 7 pages latex 2e, no figures; to appear in Int. J. Geom. Meth. Mod.
Phys | Int. J. Geom. Meth. Mod. Phys. 16 (2019) 1950030 | 10.1142/S0219887819500300 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the phantom fluid in the late universe, thus assuming the equation
of state parameter $w$ to be less than $-1$. The fluid is assumed to consist of
two components, one laminar component $\rho$ and one turbulent component
$\rho_T$, the latter set proportional to $\rho$ as well as to the Hubble
parameter, $\rho_T =3\tau H\rho$ with $\tau$ a positive constant associated
with the turbulence. The effective energy density is taken to be $\rho_e= \rho
+ \rho_T$, and the corresponding effective pressure is $p_e=w \rho_e$, with $w$
constant. These basic assumptions lead to a Big Rip universe; the physical
quantities diverging during a finite rip time $t_s$. We then consider the mass
accretion of a black hole in such a universe. The most natural assumption of
setting the rate $dM/dt$ proportional to $M^2$ times the sum $\rho_e+p_e$,
leads to a negative mass accretion, where $M(t)$ goes to zero linearly in
$(t_s-t)$ near the singularity. The Hubble parameter diverges as
$(t_s-t)^{-1}$, whereas $\rho_e$ and $p_e$ diverge as $(t_s-t)^{-2}$. We also
discuss other options and include, for the sake of comparison, some essential
properties of mass accretion in the early (inflationary) universe.
| [
{
"created": "Mon, 31 Dec 2018 14:24:35 GMT",
"version": "v1"
}
] | 2019-01-21 | [
[
"Brevik",
"Iver",
""
],
[
"Jamil",
"Mubasher",
""
]
] | We study the phantom fluid in the late universe, thus assuming the equation of state parameter $w$ to be less than $-1$. The fluid is assumed to consist of two components, one laminar component $\rho$ and one turbulent component $\rho_T$, the latter set proportional to $\rho$ as well as to the Hubble parameter, $\rho_T =3\tau H\rho$ with $\tau$ a positive constant associated with the turbulence. The effective energy density is taken to be $\rho_e= \rho + \rho_T$, and the corresponding effective pressure is $p_e=w \rho_e$, with $w$ constant. These basic assumptions lead to a Big Rip universe; the physical quantities diverging during a finite rip time $t_s$. We then consider the mass accretion of a black hole in such a universe. The most natural assumption of setting the rate $dM/dt$ proportional to $M^2$ times the sum $\rho_e+p_e$, leads to a negative mass accretion, where $M(t)$ goes to zero linearly in $(t_s-t)$ near the singularity. The Hubble parameter diverges as $(t_s-t)^{-1}$, whereas $\rho_e$ and $p_e$ diverge as $(t_s-t)^{-2}$. We also discuss other options and include, for the sake of comparison, some essential properties of mass accretion in the early (inflationary) universe. |
2209.01056 | Taylor Ordines | Taylor M. Ordines and Eric D. Carlson | Argument for the radiation-dominated behavior of matter fields in the
preinflationary era | null | null | 10.1103/PhysRevD.106.103537 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We investigate the leading-order behavior of matter fields in the
preinflationary era using the semiclassical approximation. Many inflationary
models assume without supporting arguments that the Universe was radiation
dominated prior to inflation, leading to modifications of cosmological
observables, such as the Cosmic Microwave Background power spectrum. In
previous work, we demonstrated that conformally coupled scalar fields do have a
radiation-like contribution to the stress-energy tensor at sufficiently early
times. In this work, we extend these arguments to apply to massless spin-1
fields and massive or massless spin-$\frac{1}{2}$ fields. We find massless
spin-1 fields always have a radiation-like contribution. For spin-$\frac{1}{2}$
fields, we find the contribution at early times is radiation-like assuming this
is the dominant contribution to the stress-energy tensor.
| [
{
"created": "Fri, 2 Sep 2022 13:45:07 GMT",
"version": "v1"
},
{
"created": "Mon, 12 Sep 2022 13:52:04 GMT",
"version": "v2"
}
] | 2022-12-14 | [
[
"Ordines",
"Taylor M.",
""
],
[
"Carlson",
"Eric D.",
""
]
] | We investigate the leading-order behavior of matter fields in the preinflationary era using the semiclassical approximation. Many inflationary models assume without supporting arguments that the Universe was radiation dominated prior to inflation, leading to modifications of cosmological observables, such as the Cosmic Microwave Background power spectrum. In previous work, we demonstrated that conformally coupled scalar fields do have a radiation-like contribution to the stress-energy tensor at sufficiently early times. In this work, we extend these arguments to apply to massless spin-1 fields and massive or massless spin-$\frac{1}{2}$ fields. We find massless spin-1 fields always have a radiation-like contribution. For spin-$\frac{1}{2}$ fields, we find the contribution at early times is radiation-like assuming this is the dominant contribution to the stress-energy tensor. |
gr-qc/9706038 | R. Loll | R. Loll (AEI, Potsdam) | Simplifying the spectral analysis of the volume operator | 19 pages, TeX, to be published in Nucl. Phys. B | Nucl.Phys. B500 (1997) 405-420 | 10.1016/S0550-3213(97)00334-9 | AEI-030 | gr-qc | null | The volume operator plays a central role in both the kinematics and dynamics
of canonical approaches to quantum gravity which are based on algebras of
generalized Wilson loops. We introduce a method for simplifying its spectral
analysis, for quantum states that can be realized on a cubic three-dimensional
lattice. This involves a decomposition of Hilbert space into sectors
transforming according to the irreducible representations of a subgroup of the
cubic group. As an application, we determine the complete spectrum for a class
of states with six-valent intersections.
| [
{
"created": "Fri, 13 Jun 1997 15:31:17 GMT",
"version": "v1"
}
] | 2009-10-30 | [
[
"Loll",
"R.",
"",
"AEI, Potsdam"
]
] | The volume operator plays a central role in both the kinematics and dynamics of canonical approaches to quantum gravity which are based on algebras of generalized Wilson loops. We introduce a method for simplifying its spectral analysis, for quantum states that can be realized on a cubic three-dimensional lattice. This involves a decomposition of Hilbert space into sectors transforming according to the irreducible representations of a subgroup of the cubic group. As an application, we determine the complete spectrum for a class of states with six-valent intersections. |
gr-qc/9401027 | null | Michele Maggiore | Black Holes as Quantum Membranes | 40 pages, Latex file + 6 figures | Nucl.Phys.B429:205-228,1994 | 10.1016/S0550-3213(94)80047-2 | IFUP-TH 6/94 | gr-qc hep-th | null | We propose a quantum description of black holes. The degrees of freedom to be
quantized are identified with the microscopic degrees of freedom of the
horizon, and their dynamics is governed by the action of the relatistic bosonic
membrane in $D=4$. We find that a consistent and plausible description emerges,
both at the classical and at the quantum level. We present results for the
level structure of black holes. We find a ``principal series'' of levels,
corresponding to quantization of the area of the horizon. From each level of
this principal series starts a quasi-continuum of levels due to excitations of
the membrane. We discuss the statistical origin of the black hole entropy and
the relation with Hawking radiation and with the information loss problem. The
limits of validity of the membrane approach turn out to coincide with the known
limits of validity of the thermodynamical description of black holes.
| [
{
"created": "Tue, 25 Jan 1994 18:10:08 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Maggiore",
"Michele",
""
]
] | We propose a quantum description of black holes. The degrees of freedom to be quantized are identified with the microscopic degrees of freedom of the horizon, and their dynamics is governed by the action of the relatistic bosonic membrane in $D=4$. We find that a consistent and plausible description emerges, both at the classical and at the quantum level. We present results for the level structure of black holes. We find a ``principal series'' of levels, corresponding to quantization of the area of the horizon. From each level of this principal series starts a quasi-continuum of levels due to excitations of the membrane. We discuss the statistical origin of the black hole entropy and the relation with Hawking radiation and with the information loss problem. The limits of validity of the membrane approach turn out to coincide with the known limits of validity of the thermodynamical description of black holes. |
1208.1314 | Lap-Ming Lin | Y.-H. Sham, L.-M. Lin, P. T. Leung | Radial oscillations and stability of compact stars in Eddington-inspired
Born-Infeld gravity | Minor changes to match the published version | Phys. Rev. D86:064015, 2012 | 10.1103/PhysRevD.86.064015 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the hydrostatic equilibrium structure of compact stars in the
Eddington-inspired Born-Infeld gravity recently proposed by Banados and
Ferreira [Phys. Rev. Lett. 105, 011101 (2010)]. We also develop a framework to
study the radial perturbations and stability of compact stars in this theory.
We find that the standard results of stellar stability still hold in this
theory. The frequency square of the fundamental oscillation mode vanishes for
the maximum-mass stellar configuration. The dependence of the oscillation mode
frequencies on the coupling parameter \kappa of the theory is also
investigated. We find that the fundamental mode is insensitive to the value of
\kappa, while higher order modes depend more strongly on \kappa.
| [
{
"created": "Tue, 7 Aug 2012 01:30:35 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Sep 2012 00:56:07 GMT",
"version": "v2"
}
] | 2015-06-11 | [
[
"Sham",
"Y. -H.",
""
],
[
"Lin",
"L. -M.",
""
],
[
"Leung",
"P. T.",
""
]
] | We study the hydrostatic equilibrium structure of compact stars in the Eddington-inspired Born-Infeld gravity recently proposed by Banados and Ferreira [Phys. Rev. Lett. 105, 011101 (2010)]. We also develop a framework to study the radial perturbations and stability of compact stars in this theory. We find that the standard results of stellar stability still hold in this theory. The frequency square of the fundamental oscillation mode vanishes for the maximum-mass stellar configuration. The dependence of the oscillation mode frequencies on the coupling parameter \kappa of the theory is also investigated. We find that the fundamental mode is insensitive to the value of \kappa, while higher order modes depend more strongly on \kappa. |
gr-qc/0510020 | Mark A. Miller | Mark Miller | General Relativistic Decompression of Binary Neutron Stars During
Dynamic Inspiral | Figure replaced, final published version. Dedicated to Rafael Sorkin
on his 60th birthday | Phys.Rev.D75:024001,2007 | 10.1103/PhysRevD.75.024001 | null | gr-qc astro-ph | null | We investigate the dynamic stability of inspiraling neutron stars by
performing multiple-orbit numerical relativity simulations of the binary
neutron star inspiral process. By introducing eccentricities in the orbits of
the neutron stars, significant changes in orbital separation are obtained
within orbital timescales. We find that as the binary system evolves from
apastron to periastron (as the binary separation decreases), the central rest
mass density of each star decreases, thus stabilizing the stars against
individual prompt collapse. As the binary system evolves from periastron to
apastron, the central rest mass density increases; the neutron stars
re-compress as the binary separation increases.
| [
{
"created": "Wed, 5 Oct 2005 20:15:06 GMT",
"version": "v1"
},
{
"created": "Wed, 3 Jan 2007 18:49:19 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Miller",
"Mark",
""
]
] | We investigate the dynamic stability of inspiraling neutron stars by performing multiple-orbit numerical relativity simulations of the binary neutron star inspiral process. By introducing eccentricities in the orbits of the neutron stars, significant changes in orbital separation are obtained within orbital timescales. We find that as the binary system evolves from apastron to periastron (as the binary separation decreases), the central rest mass density of each star decreases, thus stabilizing the stars against individual prompt collapse. As the binary system evolves from periastron to apastron, the central rest mass density increases; the neutron stars re-compress as the binary separation increases. |
0704.0488 | Muhammad Sharif | M. Sharif and M. Jamil Amir | Teleparallel Version of the Stationary Axisymmetric Solutions and their
Energy Contents | 18 pages, accepted for publication in Gen. Relativ. Grav | Gen.Rel.Grav.39:989-1002,2007 | 10.1007/s10714-007-0431-5 | null | gr-qc | null | This work contains the teleparallel version of the stationary axisymmetric
solutions. We obtain the tetrad and the torsion fields representing these
solutions. The tensor, vector and axial-vector parts of the torsion tensor are
evaluated. It is found that the axial-vector has component only along $\rho$
and $z$ directions. The three possibilities of the axial vector depending on
the metric function $B$ are discussed. The vector related with spin has also
been evaluated and the corresponding extra Hamiltonian is furnished. Further,
we use the teleparallel version of M$\ddot{o}$ller prescription to find the
energy-momentum distribution of the solutions. It is interesting to note that
(for $\lambda=1$) energy and momentum densities in teleparallel theory are
equal to the corresponding quantities in GR plus an additional quantity in
each, which may become equal under certain conditions. Finally, we discuss the
two special cases of the stationary axisymmetric solutions.
| [
{
"created": "Wed, 4 Apr 2007 02:49:33 GMT",
"version": "v1"
}
] | 2010-03-18 | [
[
"Sharif",
"M.",
""
],
[
"Amir",
"M. Jamil",
""
]
] | This work contains the teleparallel version of the stationary axisymmetric solutions. We obtain the tetrad and the torsion fields representing these solutions. The tensor, vector and axial-vector parts of the torsion tensor are evaluated. It is found that the axial-vector has component only along $\rho$ and $z$ directions. The three possibilities of the axial vector depending on the metric function $B$ are discussed. The vector related with spin has also been evaluated and the corresponding extra Hamiltonian is furnished. Further, we use the teleparallel version of M$\ddot{o}$ller prescription to find the energy-momentum distribution of the solutions. It is interesting to note that (for $\lambda=1$) energy and momentum densities in teleparallel theory are equal to the corresponding quantities in GR plus an additional quantity in each, which may become equal under certain conditions. Finally, we discuss the two special cases of the stationary axisymmetric solutions. |
gr-qc/9610008 | Abhay Ashtekar | Abhay Ashtekar | Large quantum gravity effects: Unexpected limitations of the classical
theory | 8 pages, No figures, ReVTeX | Phys.Rev.Lett. 77 (1996) 4864-4867 | 10.1103/PhysRevLett.77.4864 | CGPG/10-1 | gr-qc hep-th | null | 3-dimensional gravity coupled to Maxwell (or Klein-Gordon) fields is exactly
soluble under the assumption of axi-symmetry. The solution is used to probe
several quantum gravity issues. In particular, it is shown that the quantum
fluctuations in the geometry are large unless the number and frequency of
photons satisfy the inequality $\N(\hbar G\omega)^2 << 1$. Thus, even when
there is a single photon of Planckian frequency, the quantum uncertainties in
the metric are significant. Results hold also for a sector of the 4-dimensional
theory (consisting of Einstein Rosen gravitational waves).
| [
{
"created": "Tue, 8 Oct 1996 19:54:47 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Ashtekar",
"Abhay",
""
]
] | 3-dimensional gravity coupled to Maxwell (or Klein-Gordon) fields is exactly soluble under the assumption of axi-symmetry. The solution is used to probe several quantum gravity issues. In particular, it is shown that the quantum fluctuations in the geometry are large unless the number and frequency of photons satisfy the inequality $\N(\hbar G\omega)^2 << 1$. Thus, even when there is a single photon of Planckian frequency, the quantum uncertainties in the metric are significant. Results hold also for a sector of the 4-dimensional theory (consisting of Einstein Rosen gravitational waves). |
gr-qc/0508091 | Jerzy Lewandowski | Wojciech Kaminski, Jerzy Lewandowski and Marcin Bobienski | Background independent quantizations: the scalar field I | 13 pages, minor corrections were made in the revised version | Class.Quant.Grav. 23 (2006) 2761-2770 | 10.1088/0264-9381/23/9/001 | null | gr-qc hep-th math-ph math.MP | null | We are concerned with the issue of quantization of a scalar field in a
diffeomorphism invariant manner. We apply the method used in Loop Quantum
Gravity. It relies on the specific choice of scalar field variables referred to
as the polymer variables. The quantization, in our formulation, amounts to
introducing the `quantum' polymer *-star algebra and looking for positive
linear functionals, called states. The assumed in our paper homeomorphism
invariance allows to determine a complete class of the states. Except one, all
of them are new. In this letter we outline the main steps and conclusions, and
present the results: the GNS representations, characterization of those states
which lead to essentially self adjoint momentum operators (unbounded),
identification of the equivalence classes of the representations as well as of
the irreducible ones. The algebra and topology of the problem, the derivation,
all the technical details and more are contained in the paper-part II.
| [
{
"created": "Sun, 21 Aug 2005 23:06:24 GMT",
"version": "v1"
},
{
"created": "Fri, 26 Aug 2005 14:59:48 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Kaminski",
"Wojciech",
""
],
[
"Lewandowski",
"Jerzy",
""
],
[
"Bobienski",
"Marcin",
""
]
] | We are concerned with the issue of quantization of a scalar field in a diffeomorphism invariant manner. We apply the method used in Loop Quantum Gravity. It relies on the specific choice of scalar field variables referred to as the polymer variables. The quantization, in our formulation, amounts to introducing the `quantum' polymer *-star algebra and looking for positive linear functionals, called states. The assumed in our paper homeomorphism invariance allows to determine a complete class of the states. Except one, all of them are new. In this letter we outline the main steps and conclusions, and present the results: the GNS representations, characterization of those states which lead to essentially self adjoint momentum operators (unbounded), identification of the equivalence classes of the representations as well as of the irreducible ones. The algebra and topology of the problem, the derivation, all the technical details and more are contained in the paper-part II. |
1709.06892 | Muhammad Ilyas Mr. | M. Z. Bhatti, Z. Yousaf, M. Ilyas | Evolution of Compact Stars and Dark Dynamical Variables | 18 pages, 4 figures, version accepted for publication in European
Physical Journal C | Eur. Phys. J. C 77, 690 (2017) | 10.1140/epjc/s10052-017-5236-4 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This work is aimed to explore the dark dynamical effects of $f(R,T)$ modified
gravity theory on the dynamics of compact celestial star. We have taken the
interior geometry as spherical star which is filled with imperfect fluid
distribution. The modified field equations are explored by taking a particular
form of $f(R,T)$ model, i.e., $f(R,T)=f_1(R)+f_2(R)f_3(T)$. These equations are
then utilized to formulate the well-known structure scalars under the dark
dynamical effects of this higher order gravity theory. Also, the evolution
equations for expansion and shear are formulated with the help of these scalar
variables. Further, all this analysis have been made under the condition of
constant $R$ and $T$. We found a crucial significance of dark source terms and
dynamical variables on the evolution and density inhomogeneity of compact
objects.
| [
{
"created": "Tue, 19 Sep 2017 12:29:52 GMT",
"version": "v1"
}
] | 2017-11-09 | [
[
"Bhatti",
"M. Z.",
""
],
[
"Yousaf",
"Z.",
""
],
[
"Ilyas",
"M.",
""
]
] | This work is aimed to explore the dark dynamical effects of $f(R,T)$ modified gravity theory on the dynamics of compact celestial star. We have taken the interior geometry as spherical star which is filled with imperfect fluid distribution. The modified field equations are explored by taking a particular form of $f(R,T)$ model, i.e., $f(R,T)=f_1(R)+f_2(R)f_3(T)$. These equations are then utilized to formulate the well-known structure scalars under the dark dynamical effects of this higher order gravity theory. Also, the evolution equations for expansion and shear are formulated with the help of these scalar variables. Further, all this analysis have been made under the condition of constant $R$ and $T$. We found a crucial significance of dark source terms and dynamical variables on the evolution and density inhomogeneity of compact objects. |
gr-qc/0612133 | Sante Carloni | Sante Carloni, Peter K. S. Dunsby | The evolution of tensor perturbations in scalar-tensor theories of
gravity | 11 pages, 2 figures, submitted to Physical Review D | Phys.Rev.D75:064012,2007 | 10.1103/PhysRevD.75.064012 | null | gr-qc astro-ph hep-th | null | The evolution equations for tensor perturbations in a generic scalar tensor
theory of gravity are presented. Exact solution are given for a specific class
of theories and Friedmann-Lema\^{i}tre-Robertson-Walker backgrounds. In these
cases it is shown that, although the evolution of tensor models depends on the
choice of parameters of the theory, no amplification is possible if the
gravitational interaction is attractive.
| [
{
"created": "Thu, 21 Dec 2006 11:52:01 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Carloni",
"Sante",
""
],
[
"Dunsby",
"Peter K. S.",
""
]
] | The evolution equations for tensor perturbations in a generic scalar tensor theory of gravity are presented. Exact solution are given for a specific class of theories and Friedmann-Lema\^{i}tre-Robertson-Walker backgrounds. In these cases it is shown that, although the evolution of tensor models depends on the choice of parameters of the theory, no amplification is possible if the gravitational interaction is attractive. |
1604.02451 | Farook Rahaman | Alireza Sepehri, Farook Rahaman, Salvatore Capozziello, Ahmed Farag
Ali, Anirudh Pradhan | Emergence and oscillation of cosmic space by joining M1-branes | 16 pages. 4 figures. Accepted in Eur.Phys.J.C | null | 10.1140/epjc/s10052-016-4084-y | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, it has been proposed by Padmanabhan that the difference between the
number of degrees of freedom on the boundary surface and the number of degrees
of freedom in a bulk region leads to the expansion of the universe. Now, a
natural question arises, how this model could explain the oscillation of
universe between contraction and expansion branches? We try to address this
issue in the framework of BIonic system. In this model, $M0$-branes join to
each other and give rise to a pair of $M1$-anti-$M1$-branes. The fields which
live on these branes play the roles of massive gravitons that cause the
emergence of a wormhole between them and formation of a BIon system. This
wormhole dissolves into M1-branes and causes a divergence between the number of
degrees of freedom on the boundary surface of $M1$ and the bulk leading to an
expansion of $M1$-branes. When $M1$-branes become close to each other, the
square energy of their system becomes negative and some tachyonic states
emerge. To removes these states, $M1$-branes compact, the sign of compacted
gravity changes, causing the arising of anti-gravity: in this case, branes get
away from each other. By articulating $M1$-BIons, an M3-brane and an
anti-$M3$-brane are created and connected by three wormholes forming an
$M3$-BIon. This new system behaves like the initial system and by closing
branes to each other, they compact and, by getting away from each other, they
open. Our universe is located on one of these M3-branes and, by compacting
$M3$-brane, it contracts and, by opening it, it expands.
| [
{
"created": "Fri, 8 Apr 2016 08:59:50 GMT",
"version": "v1"
}
] | 2016-05-25 | [
[
"Sepehri",
"Alireza",
""
],
[
"Rahaman",
"Farook",
""
],
[
"Capozziello",
"Salvatore",
""
],
[
"Ali",
"Ahmed Farag",
""
],
[
"Pradhan",
"Anirudh",
""
]
] | Recently, it has been proposed by Padmanabhan that the difference between the number of degrees of freedom on the boundary surface and the number of degrees of freedom in a bulk region leads to the expansion of the universe. Now, a natural question arises, how this model could explain the oscillation of universe between contraction and expansion branches? We try to address this issue in the framework of BIonic system. In this model, $M0$-branes join to each other and give rise to a pair of $M1$-anti-$M1$-branes. The fields which live on these branes play the roles of massive gravitons that cause the emergence of a wormhole between them and formation of a BIon system. This wormhole dissolves into M1-branes and causes a divergence between the number of degrees of freedom on the boundary surface of $M1$ and the bulk leading to an expansion of $M1$-branes. When $M1$-branes become close to each other, the square energy of their system becomes negative and some tachyonic states emerge. To removes these states, $M1$-branes compact, the sign of compacted gravity changes, causing the arising of anti-gravity: in this case, branes get away from each other. By articulating $M1$-BIons, an M3-brane and an anti-$M3$-brane are created and connected by three wormholes forming an $M3$-BIon. This new system behaves like the initial system and by closing branes to each other, they compact and, by getting away from each other, they open. Our universe is located on one of these M3-branes and, by compacting $M3$-brane, it contracts and, by opening it, it expands. |
1702.02349 | Dnyaneshwar Pawar Dr | P. K. Agrawal and D. D. Pawar | Plane Symmetric Cosmological Model with Quark and Strange Quark Matter
in f(R,T) Theory of Gravity | Accepted for publication in Journal of Astrophysics and Astronomy,
August 2016 | null | 10.1007/s12036-016-9420-y | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We studied plane symmetric cosmological model in the presence of quark and
strange quark matter with the help of f(R,T) theory. To decipher solutions of
Plane symmetric space-time, we used power law relation between scale factor and
deceleration parameter. We considered the special law of variation of Hubble's
parameter proposed by Berman (Nuovo Cimento B 74, 182, 1983) which yields
constant deceleration parameter. We also discussed the physical behavior of the
solutions by using some physical parameters.
| [
{
"created": "Wed, 8 Feb 2017 10:04:09 GMT",
"version": "v1"
}
] | 2017-03-22 | [
[
"Agrawal",
"P. K.",
""
],
[
"Pawar",
"D. D.",
""
]
] | We studied plane symmetric cosmological model in the presence of quark and strange quark matter with the help of f(R,T) theory. To decipher solutions of Plane symmetric space-time, we used power law relation between scale factor and deceleration parameter. We considered the special law of variation of Hubble's parameter proposed by Berman (Nuovo Cimento B 74, 182, 1983) which yields constant deceleration parameter. We also discussed the physical behavior of the solutions by using some physical parameters. |
2403.12679 | Francesco Sannino | Manuel Del Piano, Stefan Hohenegger and Francesco Sannino | Effective Metric Descriptions of Quantum Black Holes | 24 pages, 4 figures | null | null | null | gr-qc hep-ph hep-th | http://creativecommons.org/licenses/by/4.0/ | In a recent work [arXiv:2307.13489 [gr-qc]], we have described spherically
symmetric and static quantum black holes as deformations of the classical
Schwarzschild metric that depend on the physical distance to the horizon. We
have developed a framework that allows to compute the latter in a
self-consistent fashion from the deformed geometry, in the vicinity of the
horizon. However, in this formalism, the distance can be replaced by other
physical quantities, e.g. curvature invariants such as the Ricci- or
Kretschmann scalar. Here, we therefore define a more general framework, which
we call an "effective metric description" (EMD), that captures the deformed
geometry based on a generic physical quantity. We develop in detail the Ricci-
and Kretschmann scalar EMD, in particular demonstrating how to compute the
geometry in a self-consistent manner. Moreover, we provide explicit relations
that allow to express one EMD in terms of the others, thus demonstrating their
equivalence.
| [
{
"created": "Tue, 19 Mar 2024 12:30:38 GMT",
"version": "v1"
}
] | 2024-03-20 | [
[
"Del Piano",
"Manuel",
""
],
[
"Hohenegger",
"Stefan",
""
],
[
"Sannino",
"Francesco",
""
]
] | In a recent work [arXiv:2307.13489 [gr-qc]], we have described spherically symmetric and static quantum black holes as deformations of the classical Schwarzschild metric that depend on the physical distance to the horizon. We have developed a framework that allows to compute the latter in a self-consistent fashion from the deformed geometry, in the vicinity of the horizon. However, in this formalism, the distance can be replaced by other physical quantities, e.g. curvature invariants such as the Ricci- or Kretschmann scalar. Here, we therefore define a more general framework, which we call an "effective metric description" (EMD), that captures the deformed geometry based on a generic physical quantity. We develop in detail the Ricci- and Kretschmann scalar EMD, in particular demonstrating how to compute the geometry in a self-consistent manner. Moreover, we provide explicit relations that allow to express one EMD in terms of the others, thus demonstrating their equivalence. |
gr-qc/9906126 | Steven Carlip | S. Carlip | Entropy from Conformal Field Theory at Killing Horizons | 26 pages, LaTeX; corrected typo and minor changes in Misner string
section | Class.Quant.Grav.16:3327-3348,1999 | 10.1088/0264-9381/16/10/322 | UCD-99-12, NSF-ITP-99-069 | gr-qc hep-th | null | On a manifold with boundary, the constraint algebra of general relativity may
acquire a central extension, which can be computed using covariant phase space
techniques. When the boundary is a (local) Killing horizon, a natural set of
boundary conditions leads to a Virasoro subalgebra with a calculable central
charge. Conformal field theory methods may then be used to determine the
density of states at the boundary. I consider a number of cases---black holes,
Rindler space, de Sitter space, Taub-NUT and Taub-Bolt spaces, and dilaton
gravity---and show that the resulting density of states yields the expected
Bekenstein-Hawking entropy. The statistical mechanics of black hole entropy may
thus be fixed by symmetry arguments, independent of details of quantum gravity.
| [
{
"created": "Wed, 30 Jun 1999 23:53:02 GMT",
"version": "v1"
},
{
"created": "Mon, 9 Aug 1999 23:24:59 GMT",
"version": "v2"
}
] | 2010-04-28 | [
[
"Carlip",
"S.",
""
]
] | On a manifold with boundary, the constraint algebra of general relativity may acquire a central extension, which can be computed using covariant phase space techniques. When the boundary is a (local) Killing horizon, a natural set of boundary conditions leads to a Virasoro subalgebra with a calculable central charge. Conformal field theory methods may then be used to determine the density of states at the boundary. I consider a number of cases---black holes, Rindler space, de Sitter space, Taub-NUT and Taub-Bolt spaces, and dilaton gravity---and show that the resulting density of states yields the expected Bekenstein-Hawking entropy. The statistical mechanics of black hole entropy may thus be fixed by symmetry arguments, independent of details of quantum gravity. |
2112.06626 | Yakov Shnir | J. Kunz, V. Loiko and Ya. Shnir | $U(1)$ gauged boson stars in the Einstein-Friedberg-Lee-Sirlin model | 18 pages, 8 figures | null | 10.1103/PhysRevD.105.085013 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider spherically symmetric $U(1)$ gauged boson stars in the
two-component scalar Friedberg-Lee-Sirlin model with a symmetry breaking
potential in 3+1 dimensional spacetime. Depending on the relative strength of
gravity and the electromagnetic interaction, the resulting boson stars exhibit
either the typical properties of ungauged boson stars, or their behavior
resembles the pattern found for gauged Q-balls of the Friedberg-Lee-Sirlin
model in flat spacetime, both for a finite and a vanishing potential.
| [
{
"created": "Mon, 13 Dec 2021 13:10:32 GMT",
"version": "v1"
}
] | 2022-05-04 | [
[
"Kunz",
"J.",
""
],
[
"Loiko",
"V.",
""
],
[
"Shnir",
"Ya.",
""
]
] | We consider spherically symmetric $U(1)$ gauged boson stars in the two-component scalar Friedberg-Lee-Sirlin model with a symmetry breaking potential in 3+1 dimensional spacetime. Depending on the relative strength of gravity and the electromagnetic interaction, the resulting boson stars exhibit either the typical properties of ungauged boson stars, or their behavior resembles the pattern found for gauged Q-balls of the Friedberg-Lee-Sirlin model in flat spacetime, both for a finite and a vanishing potential. |
gr-qc/0609005 | Antonio Brotas | A. Brotas | Fishing in Black Holes | 4 pages, plain LaTex | null | null | null | gr-qc | null | The coordinate system $(\bar{x},\bar{t})$ defined by $r = 2m + K\bar{x}- c K
\bar{t}$ and $t=\bar{x}/cK - 1 /cK \int_{r_a}^r (1- 2m/r + K^2)^{1/2} (1 -
2m/r)^{-1}dr$ allow us to write the Schwarzschild metric in the form:
\[ds^2=c^2 d\bar{t}^2 + (W^2/K^2 - 2W/K) d\bar{x}^2 + 2c (1 + W/K)
d\bar{x}d\bar{t} - r^2 (d\theta^2 + cos^2\theta d\phi^2)\] with $W=(1 - 2m/r +
K^2)^{1/2}$, in which the coefficients' pathologies are moved to $r_K =
2m/(1+K^2)$. This new coordinate system is used to study the entrance into a
black hole of a rigid line (a line in which the shock waves propagate with
velocity c).
| [
{
"created": "Fri, 1 Sep 2006 13:05:59 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Brotas",
"A.",
""
]
] | The coordinate system $(\bar{x},\bar{t})$ defined by $r = 2m + K\bar{x}- c K \bar{t}$ and $t=\bar{x}/cK - 1 /cK \int_{r_a}^r (1- 2m/r + K^2)^{1/2} (1 - 2m/r)^{-1}dr$ allow us to write the Schwarzschild metric in the form: \[ds^2=c^2 d\bar{t}^2 + (W^2/K^2 - 2W/K) d\bar{x}^2 + 2c (1 + W/K) d\bar{x}d\bar{t} - r^2 (d\theta^2 + cos^2\theta d\phi^2)\] with $W=(1 - 2m/r + K^2)^{1/2}$, in which the coefficients' pathologies are moved to $r_K = 2m/(1+K^2)$. This new coordinate system is used to study the entrance into a black hole of a rigid line (a line in which the shock waves propagate with velocity c). |
1812.04505 | Dennis R\"atzel | Fabienne Schneiter, Dennis R\"atzel, Daniel Braun | Rotation of polarization in the gravitational field of a laser beam -
Faraday effect and optical activity | null | null | 10.1088/1361-6382/ab3523 | null | gr-qc hep-th physics.optics quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the rotation of the polarization of a light ray propagating in
the gravitational field of a circularly polarized laser beam. The rotation
consists of a reciprocal part due to gravitational optical activity, and a
non-reciprocal part due to the gravitational Faraday effect. We discuss how to
distinguish the two effects: Letting light propagate back and forth between two
mirrors, the rotation due to gravitational optical activity cancels while the
rotation due to the gravitational Faraday effect accumulates. In contrast, the
rotation due to both effects accumulates in a ring cavity and a situation can
be created in which gravitational optical activity dominates. Such setups
amplify the effects by up to five orders of magnitude, which however is not
enough to make them measurable with state of the art technology. The effects
are of conceptual interest as they reveal gravitational spin-spin coupling in
the realm of classical general relativity, a phenomenon which occurs in
perturbative quantum gravity.
| [
{
"created": "Tue, 11 Dec 2018 16:00:57 GMT",
"version": "v1"
},
{
"created": "Fri, 22 Feb 2019 10:43:30 GMT",
"version": "v2"
}
] | 2020-01-08 | [
[
"Schneiter",
"Fabienne",
""
],
[
"Rätzel",
"Dennis",
""
],
[
"Braun",
"Daniel",
""
]
] | We investigate the rotation of the polarization of a light ray propagating in the gravitational field of a circularly polarized laser beam. The rotation consists of a reciprocal part due to gravitational optical activity, and a non-reciprocal part due to the gravitational Faraday effect. We discuss how to distinguish the two effects: Letting light propagate back and forth between two mirrors, the rotation due to gravitational optical activity cancels while the rotation due to the gravitational Faraday effect accumulates. In contrast, the rotation due to both effects accumulates in a ring cavity and a situation can be created in which gravitational optical activity dominates. Such setups amplify the effects by up to five orders of magnitude, which however is not enough to make them measurable with state of the art technology. The effects are of conceptual interest as they reveal gravitational spin-spin coupling in the realm of classical general relativity, a phenomenon which occurs in perturbative quantum gravity. |
1603.00172 | Thomas Krajewski | Thomas Krajewski, Reiko Toriumi | Exact Renormalisation Group Equations and Loop Equations for Tensor
Models | null | SIGMA 12 (2016), 068, 36 pages | 10.3842/SIGMA.2016.068 | null | gr-qc hep-th | http://creativecommons.org/licenses/by-sa/4.0/ | In this paper, we review some general formulations of exact renormalisation
group equations and loop equations for tensor models and tensorial group field
theories. We illustrate the use of these equations in the derivation of the
leading order expectation values of observables in tensor models. Furthermore,
we use the exact renormalisation group equations to establish a suitable
scaling dimension for interactions in Abelian tensorial group field theories
with a closure constraint. We also present analogues of the loop equations for
tensor models.
| [
{
"created": "Tue, 1 Mar 2016 07:57:48 GMT",
"version": "v1"
},
{
"created": "Mon, 18 Jul 2016 06:27:13 GMT",
"version": "v2"
}
] | 2016-07-19 | [
[
"Krajewski",
"Thomas",
""
],
[
"Toriumi",
"Reiko",
""
]
] | In this paper, we review some general formulations of exact renormalisation group equations and loop equations for tensor models and tensorial group field theories. We illustrate the use of these equations in the derivation of the leading order expectation values of observables in tensor models. Furthermore, we use the exact renormalisation group equations to establish a suitable scaling dimension for interactions in Abelian tensorial group field theories with a closure constraint. We also present analogues of the loop equations for tensor models. |
2103.07777 | Anna Chrysostomou | Chun-Hung Chen, Hing-Tong Cho, Anna Chrysostomou and Alan S. Cornell | Quasinormal modes for integer and half-integer spins within the large
angular momentum limit | 46 pages; added commentary on implementation procedure in Sec. III-A
(results unchanged); references added; to appear in Physical Review D (PRD) | Phys. Rev. D 104, 024009 (2021) | 10.1103/PhysRevD.104.024009 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | While independent observations have been made regarding the behaviour of
effective quasinormal mode (QNM) potentials within the large angular momentum
limit, we demonstrate analytically here that a uniform expression emerges for
non-rotating, higher-dimensional, and spherically-symmetric black holes (BHs)
in this regime for fields of integer and half-integer spin in asymptotically
flat and dS BH contexts; a second uniform expression arises for these QNM
potentials in AdS BH spacetimes. We then proceed with a numerical analysis
based on the multipolar expansion method recently proposed by Dolan and
Ottewill to determine the behaviour of quasinormal frequencies (QNF) for
varying BH parameters in the eikonal limit. We perform a complete study of
Dolan and Ottewill's method for perturbations of spin $s \in \{0,1/2,1,3/2,2
\}$ in 4D Schwarzschild, Reissner-Nordstr{\"o}m, and Schwarzschild de Sitter
spacetimes, clarifying expressions and presenting expansions and results to
higher orders $(\mathcal{O}(L^{-6}))$ than many of those presented in the
literature $(\sim \mathcal{O}(L^{-2}))$. We find good agreement with known
results of QNFs for low-lying modes; in the large-$\ell$ regime, our results
are highly consistent with those of Konoplya's 6th-order WKB method. We confirm
a universality in the trends of physical features recorded in the literature
for the low-lying QNFs (that the real part grows indefinitely, the imaginary
tends to a constant as $\ell \rightarrow \infty$, etc.) as we approach large
values of $\ell$ within these spacetimes, and explore the consequent interplay
between BH parameters and QNFs in the eikonal limit.
| [
{
"created": "Sat, 13 Mar 2021 19:28:12 GMT",
"version": "v1"
},
{
"created": "Wed, 7 Jul 2021 13:08:00 GMT",
"version": "v2"
}
] | 2021-07-14 | [
[
"Chen",
"Chun-Hung",
""
],
[
"Cho",
"Hing-Tong",
""
],
[
"Chrysostomou",
"Anna",
""
],
[
"Cornell",
"Alan S.",
""
]
] | While independent observations have been made regarding the behaviour of effective quasinormal mode (QNM) potentials within the large angular momentum limit, we demonstrate analytically here that a uniform expression emerges for non-rotating, higher-dimensional, and spherically-symmetric black holes (BHs) in this regime for fields of integer and half-integer spin in asymptotically flat and dS BH contexts; a second uniform expression arises for these QNM potentials in AdS BH spacetimes. We then proceed with a numerical analysis based on the multipolar expansion method recently proposed by Dolan and Ottewill to determine the behaviour of quasinormal frequencies (QNF) for varying BH parameters in the eikonal limit. We perform a complete study of Dolan and Ottewill's method for perturbations of spin $s \in \{0,1/2,1,3/2,2 \}$ in 4D Schwarzschild, Reissner-Nordstr{\"o}m, and Schwarzschild de Sitter spacetimes, clarifying expressions and presenting expansions and results to higher orders $(\mathcal{O}(L^{-6}))$ than many of those presented in the literature $(\sim \mathcal{O}(L^{-2}))$. We find good agreement with known results of QNFs for low-lying modes; in the large-$\ell$ regime, our results are highly consistent with those of Konoplya's 6th-order WKB method. We confirm a universality in the trends of physical features recorded in the literature for the low-lying QNFs (that the real part grows indefinitely, the imaginary tends to a constant as $\ell \rightarrow \infty$, etc.) as we approach large values of $\ell$ within these spacetimes, and explore the consequent interplay between BH parameters and QNFs in the eikonal limit. |
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