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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
gr-qc/0403025 | Sawa Manoff | Sawa Manoff | Determination of the velocity of an emitter in spaces with affine
connections and metrics | 16 pages, LaTeX. Invited talk represented at the International
Seminar dedicated to the 75th Anniversary of A.N. Chernikov | null | null | null | gr-qc astro-ph | null | Doppler effect and Hubble effect in different models of space-time related to
the space-time velocity of an observer are considered. The Doppler effect and
Doppler shift frequency parameter are connected with the kinematic
characteristics of the relative velocity and the relative acceleration of the
emitter with respect to the observer (detector). The Hubble effect and Hubble
shift frequency parameter are considered in analogous way. It is shown that by
the use of the variation of the shift frequency parameter during a time period,
considered locally in the proper frame of reference of an observer, one can
directly determine the radial (centrifugal, centripetal) relative velocity and
acceleration as well as the tangential (Coriolis) relative velocity and
acceleration of an astronomical object moving relatively to the observer. All
results are obtained on purely kinematic basis without taking into account the
dynamic reasons for the considered effect. PACS numbers: 98.80.Jk; 98.62.Py;
04.90.+e; 04.80.Cc
| [
{
"created": "Thu, 4 Mar 2004 15:22:21 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Manoff",
"Sawa",
""
]
] | Doppler effect and Hubble effect in different models of space-time related to the space-time velocity of an observer are considered. The Doppler effect and Doppler shift frequency parameter are connected with the kinematic characteristics of the relative velocity and the relative acceleration of the emitter with respect to the observer (detector). The Hubble effect and Hubble shift frequency parameter are considered in analogous way. It is shown that by the use of the variation of the shift frequency parameter during a time period, considered locally in the proper frame of reference of an observer, one can directly determine the radial (centrifugal, centripetal) relative velocity and acceleration as well as the tangential (Coriolis) relative velocity and acceleration of an astronomical object moving relatively to the observer. All results are obtained on purely kinematic basis without taking into account the dynamic reasons for the considered effect. PACS numbers: 98.80.Jk; 98.62.Py; 04.90.+e; 04.80.Cc |
2305.12591 | Valeri Frolov P | Noah P. Baker and Valeri P. Frolov | Charged Particle Motion Near a Magnetized Black Hole: A Near-Horizon
Approximation | 14 pages, 5 figures. New references added. Typos are corrected | null | 10.1103/PhysRevD.108.024045 | null | gr-qc astro-ph.HE hep-th | http://creativecommons.org/licenses/by/4.0/ | In this paper, the orbits of a charged particle near the event horizon of a
magnetized black hole are investigated. For a static black hole of mass $M$
immersed in a homogeneous magnetic field $B$, the dimensionless parameter
$b=eBGM/ (mc^4)$ controls the radius of the circular orbits and determines the
position of the innermost stable circular orbit (ISCO), where $m$ and $e$ are
the mass and charge of the particle. For large values of the parameter $b$, the
ISCO radius can be very close to the gravitational radius. We demonstrate that
the properties of such orbits can be effectively and easily found by using a
properly constructed ``near-horizon approximation''. In particular, we show
that the effective potential (which determines the position of the orbit) can
be written in a form which is invariant under rescaling of the magnetic field,
and as a result is universal in this sense. We also demonstrate that in the
near-horizon approximation, the particle orbits are stationary worldlines in
Minkowski spacetime. We use this property to solve the equation describing slow
changes in the distance of the particle orbit from the horizon, which arise as
a result of the electromagnetic field radiated by the particle itself. This
allows us to evaluate the life-time of the particle before it reaches the ISCO
and ultimately falls into the black hole.
| [
{
"created": "Sun, 21 May 2023 23:01:19 GMT",
"version": "v1"
},
{
"created": "Fri, 26 May 2023 19:05:33 GMT",
"version": "v2"
},
{
"created": "Thu, 29 Jun 2023 23:27:21 GMT",
"version": "v3"
}
] | 2023-08-02 | [
[
"Baker",
"Noah P.",
""
],
[
"Frolov",
"Valeri P.",
""
]
] | In this paper, the orbits of a charged particle near the event horizon of a magnetized black hole are investigated. For a static black hole of mass $M$ immersed in a homogeneous magnetic field $B$, the dimensionless parameter $b=eBGM/ (mc^4)$ controls the radius of the circular orbits and determines the position of the innermost stable circular orbit (ISCO), where $m$ and $e$ are the mass and charge of the particle. For large values of the parameter $b$, the ISCO radius can be very close to the gravitational radius. We demonstrate that the properties of such orbits can be effectively and easily found by using a properly constructed ``near-horizon approximation''. In particular, we show that the effective potential (which determines the position of the orbit) can be written in a form which is invariant under rescaling of the magnetic field, and as a result is universal in this sense. We also demonstrate that in the near-horizon approximation, the particle orbits are stationary worldlines in Minkowski spacetime. We use this property to solve the equation describing slow changes in the distance of the particle orbit from the horizon, which arise as a result of the electromagnetic field radiated by the particle itself. This allows us to evaluate the life-time of the particle before it reaches the ISCO and ultimately falls into the black hole. |
gr-qc/0008010 | Giovanni Amelino-Camelia | Giovanni Amelino-Camelia | Planck-Length Phenomenology | Paper awarded an ``honorable mention'' in the Annual Competition of
the Gravity Research Foundation for the year 2000 (LaTex, 7 pages, no
figures) | Int.J.Mod.Phys. D10 (2001) 1-8 | 10.1142/S0218271801001128 | null | gr-qc | null | This author's recent proposal of interferometric tests of
Planck-scale-related properties of space-time is here revisited from a strictly
phenomenological viewpoint. The results announced previously are rederived
using elementary dimensional considerations. The dimensional analysis is then
extended to the other two classes of experiments (observations of neutral kaons
at particle accelerators and observations of the gamma rays we detect from
distant astrophysical sources) which have been recently considered as
opportunities to explore "foamy" properties of space-time. The emerging picture
suggests that there is an objective and intuitive way to connect the
sensitivities of these three experiments with the Planck length. While in
previous studies the emphasis was always on some quantum-gravity scenario and
the analysis was always primarily aimed at showing that the chosen scenario
would leave a trace in a certain class of doable experiments, the analysis here
reported takes as starting point the experiments and, by relating in a direct
quantitative way the sensitivities to the Planck length, provides a
model-independent description of the status of Planck-length phenomenology.
| [
{
"created": "Fri, 4 Aug 2000 11:49:28 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Amelino-Camelia",
"Giovanni",
""
]
] | This author's recent proposal of interferometric tests of Planck-scale-related properties of space-time is here revisited from a strictly phenomenological viewpoint. The results announced previously are rederived using elementary dimensional considerations. The dimensional analysis is then extended to the other two classes of experiments (observations of neutral kaons at particle accelerators and observations of the gamma rays we detect from distant astrophysical sources) which have been recently considered as opportunities to explore "foamy" properties of space-time. The emerging picture suggests that there is an objective and intuitive way to connect the sensitivities of these three experiments with the Planck length. While in previous studies the emphasis was always on some quantum-gravity scenario and the analysis was always primarily aimed at showing that the chosen scenario would leave a trace in a certain class of doable experiments, the analysis here reported takes as starting point the experiments and, by relating in a direct quantitative way the sensitivities to the Planck length, provides a model-independent description of the status of Planck-length phenomenology. |
2010.00120 | Vijay Varma | Afura Taylor and Vijay Varma | Gravitational wave peak luminosity model for precessing binary black
holes | 5 pages, 4 figures; matches PRD version | Phys. Rev. D 102, 104047 (2020) | 10.1103/PhysRevD.102.104047 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | When two black holes merge, a tremendous amount of energy is released in the
form of gravitational radiation in a short span of time, making such events
among the most luminous phenomenon in the universe. Models that predict the
peak luminosity of black hole mergers are of interest to the gravitational wave
community, with potential applications in tests of general relativity. We
present a surrogate model for the peak luminosity that is directly trained on
numerical relativity simulations of precessing binary black holes. Using
Gaussian process regression, we interpolate the peak luminosity in the
7-dimensional parameter space of precessing binaries with mass ratios $q\leq4$,
and spin magnitudes $\chi_1,\chi_2\leq0.8$. We demonstrate that our errors in
estimating the peak luminosity are lower than those of existing fitting
formulae by about an order of magnitude. In addition, we construct a model for
the peak luminosity of aligned-spin binaries with mass ratios $q\leq8$, and
spin magnitudes $|\chi_{1z}|,|\chi_{2z}|\leq0.8$. We apply our precessing model
to infer the peak luminosity of the GW event GW190521, and find the results to
be consistent with previous predictions.
| [
{
"created": "Wed, 30 Sep 2020 21:53:40 GMT",
"version": "v1"
},
{
"created": "Wed, 18 Nov 2020 17:42:33 GMT",
"version": "v2"
}
] | 2020-11-25 | [
[
"Taylor",
"Afura",
""
],
[
"Varma",
"Vijay",
""
]
] | When two black holes merge, a tremendous amount of energy is released in the form of gravitational radiation in a short span of time, making such events among the most luminous phenomenon in the universe. Models that predict the peak luminosity of black hole mergers are of interest to the gravitational wave community, with potential applications in tests of general relativity. We present a surrogate model for the peak luminosity that is directly trained on numerical relativity simulations of precessing binary black holes. Using Gaussian process regression, we interpolate the peak luminosity in the 7-dimensional parameter space of precessing binaries with mass ratios $q\leq4$, and spin magnitudes $\chi_1,\chi_2\leq0.8$. We demonstrate that our errors in estimating the peak luminosity are lower than those of existing fitting formulae by about an order of magnitude. In addition, we construct a model for the peak luminosity of aligned-spin binaries with mass ratios $q\leq8$, and spin magnitudes $|\chi_{1z}|,|\chi_{2z}|\leq0.8$. We apply our precessing model to infer the peak luminosity of the GW event GW190521, and find the results to be consistent with previous predictions. |
1911.06280 | Aritra Ghosh | Aritra Ghosh and Chandrasekhar Bhamidipati | Thermodynamic geometry for charged Gauss-Bonnet black holes in AdS
spacetimes | 26 pages, 8 figures; v3: refs added, revised version; v4: typos
corrected | Phys. Rev. D 101, 046005 (2020) | 10.1103/PhysRevD.101.046005 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we study the thermodynamic geometry of charged Gauss-Bonnet
black holes (and Reissner-Nordstr\"{o}m black holes, for the sake of
comparison) in AdS: in both $(T,V)$- and $(S,P)$-planes. The thermodynamic
phase space is known to have an underlying contact and metric structure;
Ruppeiner geometry then naturally arises in this framework. Sign of Ruppeiner
curvature can be used to probe the nature of interactions between the black
hole microstructures. It is found that there are both attraction and repulsion
dominated regions which are in general determined by the electric charge,
Gauss-Bonnet coupling and horizon radius of the black hole. The results are
physically explained by considering that these black hole systems consist of
charged as well as neutral microstructures much like a binary mixture of
fluids.
| [
{
"created": "Thu, 14 Nov 2019 18:03:49 GMT",
"version": "v1"
},
{
"created": "Wed, 11 Dec 2019 06:42:40 GMT",
"version": "v2"
},
{
"created": "Tue, 28 Jan 2020 18:35:09 GMT",
"version": "v3"
},
{
"created": "Thu, 7 May 2020 18:32:52 GMT",
"version": "v4"
}
] | 2020-05-11 | [
[
"Ghosh",
"Aritra",
""
],
[
"Bhamidipati",
"Chandrasekhar",
""
]
] | In this paper, we study the thermodynamic geometry of charged Gauss-Bonnet black holes (and Reissner-Nordstr\"{o}m black holes, for the sake of comparison) in AdS: in both $(T,V)$- and $(S,P)$-planes. The thermodynamic phase space is known to have an underlying contact and metric structure; Ruppeiner geometry then naturally arises in this framework. Sign of Ruppeiner curvature can be used to probe the nature of interactions between the black hole microstructures. It is found that there are both attraction and repulsion dominated regions which are in general determined by the electric charge, Gauss-Bonnet coupling and horizon radius of the black hole. The results are physically explained by considering that these black hole systems consist of charged as well as neutral microstructures much like a binary mixture of fluids. |
1211.2047 | Prabir Rudra | Prabir Rudra | Emergent Universe With Exotic Matter In Loop Quantum Cosmology, DGP
Brane World and Kaluza-Klein Cosmology | 13 pages, 16 figures, 1 table. arXiv admin note: text overlap with
arXiv:1105.1091 | Modern Physics Letters A, Vol. 27, No. 33 (2012) 1250189 | 10.1142/S0217732312501891 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we have investigated the emergent scenario of the universe
described by Loop quantum cosmology model, DGP brane model and Kaluza-Klein
cosmology. Scalar field along with barotropic fluid as normal matter is
considered as the matter content of the universe. In Loop quantum cosmology it
is found that the emergent scenario is realized with the imposition of some
conditions on the value of the density of normal matter in case of normal and
phantom scalar field. This is a surprising result indeed considering the fact
that scalar field is the dominating matter component. In case of Tachyonic
field, emergent scenario is realized with some constraints on the value of
$\rho_{1}$ for both normal and phantom tachyon. In case of DGP brane-world
realization of an emergent scenario is possible almost unconditionally for
normal and phantom fields. Plots and table have been generated to testify this
fact. In case of tachyonic field emergent scenario is realized with some
constraints on $\dot{H}$. In Kaluza-Klein cosmology emergent scenario is
possible only for a closed universe in case of normal and phantom scalar field.
For a tachyonic field realization of emergent universe is possible for all
models(closed, open and flat).
| [
{
"created": "Fri, 9 Nov 2012 05:39:43 GMT",
"version": "v1"
}
] | 2012-11-12 | [
[
"Rudra",
"Prabir",
""
]
] | In this work we have investigated the emergent scenario of the universe described by Loop quantum cosmology model, DGP brane model and Kaluza-Klein cosmology. Scalar field along with barotropic fluid as normal matter is considered as the matter content of the universe. In Loop quantum cosmology it is found that the emergent scenario is realized with the imposition of some conditions on the value of the density of normal matter in case of normal and phantom scalar field. This is a surprising result indeed considering the fact that scalar field is the dominating matter component. In case of Tachyonic field, emergent scenario is realized with some constraints on the value of $\rho_{1}$ for both normal and phantom tachyon. In case of DGP brane-world realization of an emergent scenario is possible almost unconditionally for normal and phantom fields. Plots and table have been generated to testify this fact. In case of tachyonic field emergent scenario is realized with some constraints on $\dot{H}$. In Kaluza-Klein cosmology emergent scenario is possible only for a closed universe in case of normal and phantom scalar field. For a tachyonic field realization of emergent universe is possible for all models(closed, open and flat). |
1112.5763 | Jose' P. S. Lemos | Jos\'e P. S. Lemos | Black holes and quasiblack holes: Some history and remarks | 12 pages, 3 figures. Scientific Proceedings of Kazan State University
(Uchenye Zapiski Kazanskogo Universiteta (UZKGU)) (2011), ed. A. Aminova.
Based on the Invited Lecture in the Petrov 2010 Anniversary Symposium on
General Relativity and Gravitation, Kazan, Russia, November 1-6, 2010 | Uch.Zap.Kazan.Univers.153:215,2011 | null | null | gr-qc astro-ph.SR hep-th physics.hist-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A brief reference to the two Schwarzschild solutions and what Petrov had to
say about them is given. Comments on how the Schwarzschild vacuum solution
describes a black hole are also provided. Then we compare the properties,
differences and similarities between black holes and quasiblack holes. Black
holes are well known. Quasiblack hole is a new concept. A quasiblack hole,
either nonextremal or extremal, can be broadly defined as the limiting
configuration of a body when its boundary approaches the body's own
gravitational radius (the quasihorizon). They are objects that are on the verge
of being black holes but actually are distinct from them in many ways. We
display some of their properties: there are infinite redshift whole regions;
the curvature invariants remain perfectly regular everywhere, in the quasiblack
hole limit; a free-falling observer finds in his own frame infinitely large
tidal forces in the whole inner region, showing some form of degeneracy; outer
and inner regions become mutually impenetrable and disjoint, although, in
contrast to the usual black holes, this separation is of a dynamical nature,
rather than purely causal; for external far away observers the spacetime is
virtually indistinguishable from that of extremal black holes. Other important
properties, such as the mass formula, and the entropy, are also discussed and
compared to the corresponding properties of black holes.
| [
{
"created": "Sun, 25 Dec 2011 02:08:19 GMT",
"version": "v1"
}
] | 2012-11-09 | [
[
"Lemos",
"José P. S.",
""
]
] | A brief reference to the two Schwarzschild solutions and what Petrov had to say about them is given. Comments on how the Schwarzschild vacuum solution describes a black hole are also provided. Then we compare the properties, differences and similarities between black holes and quasiblack holes. Black holes are well known. Quasiblack hole is a new concept. A quasiblack hole, either nonextremal or extremal, can be broadly defined as the limiting configuration of a body when its boundary approaches the body's own gravitational radius (the quasihorizon). They are objects that are on the verge of being black holes but actually are distinct from them in many ways. We display some of their properties: there are infinite redshift whole regions; the curvature invariants remain perfectly regular everywhere, in the quasiblack hole limit; a free-falling observer finds in his own frame infinitely large tidal forces in the whole inner region, showing some form of degeneracy; outer and inner regions become mutually impenetrable and disjoint, although, in contrast to the usual black holes, this separation is of a dynamical nature, rather than purely causal; for external far away observers the spacetime is virtually indistinguishable from that of extremal black holes. Other important properties, such as the mass formula, and the entropy, are also discussed and compared to the corresponding properties of black holes. |
2001.08391 | Cosimo Bambi | Ashutosh Tripathi, Menglei Zhou, Askar B. Abdikamalov, Dimitry
Ayzenberg, Cosimo Bambi, Lijun Gou, Victoria Grinberg, Honghui Liu, James F.
Steiner | Testing general relativity with the stellar-mass black hole in LMC X-1
using the continuum-fitting method | 7 pages, 3 figures. v2: refereed version | Astrophys.J. 897: 84 (2020) | 10.3847/1538-4357/ab9600 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The iron line and the continuum-fitting methods are currently the two leading
techniques for measuring black hole spins with electromagnetic radiation. They
can be naturally extended for probing the spacetime geometry around black holes
and testing general relativity in the strong field regime. In the past couple
of years, there has been significant work to use the iron line method to test
the nature of black holes. In this Letter, we use the continuum-fitting method
and we show its capability of constraining the spacetime geometry around black
holes by analyzing 17 RXTE data of the X-ray binary LMC X-1.
| [
{
"created": "Thu, 23 Jan 2020 07:31:21 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Jul 2020 09:51:15 GMT",
"version": "v2"
}
] | 2020-07-07 | [
[
"Tripathi",
"Ashutosh",
""
],
[
"Zhou",
"Menglei",
""
],
[
"Abdikamalov",
"Askar B.",
""
],
[
"Ayzenberg",
"Dimitry",
""
],
[
"Bambi",
"Cosimo",
""
],
[
"Gou",
"Lijun",
""
],
[
"Grinberg",
"Victoria",
""
... | The iron line and the continuum-fitting methods are currently the two leading techniques for measuring black hole spins with electromagnetic radiation. They can be naturally extended for probing the spacetime geometry around black holes and testing general relativity in the strong field regime. In the past couple of years, there has been significant work to use the iron line method to test the nature of black holes. In this Letter, we use the continuum-fitting method and we show its capability of constraining the spacetime geometry around black holes by analyzing 17 RXTE data of the X-ray binary LMC X-1. |
1103.6041 | Emanuele Berti | Zhongyang Zhang, Nicolas Yunes, Emanuele Berti | Accuracy of the post-Newtonian approximation. II. Optimal asymptotic
expansion of the energy flux for quasicircular, extreme mass-ratio inspirals
into a Kerr black hole | 9 pages, 8 figures. Minor changes to match published version | Phys.Rev.D84:024029,2011 | 10.1103/PhysRevD.84.024029 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the effect of black hole spin on the accuracy of the post-Newtonian
approximation. We focus on the gravitational energy flux for the quasicircular,
equatorial, extreme mass-ratio inspiral of a compact object into a Kerr black
hole of mass M and spin J. For a given dimensionless spin a=J/M^2 (in
geometrical units), the energy flux depends only on the orbital velocity v or
(equivalently) on the Boyer-Lindquist orbital radius r. We investigate the
formal region of validity of the Taylor post-Newtonian expansion of the energy
flux (which is known up to order v^8 beyond the quadrupole formula),
generalizing previous work by two of us. The "error function" used to determine
the region of validity of the post-Newtonian expansion can have two
qualitatively different kinds of behavior, and we deal with these two cases
separately. We find that, at any fixed post-Newtonian order, the edge of the
region of validity (as measured by v/v_{ISCO}, where v_{ISCO} is the orbital
velocity at the innermost stable circular orbit) is only weakly dependent on a.
Unlike in the nonspinning case, the lack of sufficiently high order terms does
not allow us to determine if there is a convergent to divergent transition at
order v^6. Independently of a, the inclusion of angular multipoles up to and
including l=5 in the numerical flux is necessary to achieve the level of
accuracy of the best-known (N=8) PN expansion of the energy flux.
| [
{
"created": "Wed, 30 Mar 2011 20:05:45 GMT",
"version": "v1"
},
{
"created": "Mon, 18 Jul 2011 05:29:36 GMT",
"version": "v2"
}
] | 2011-08-08 | [
[
"Zhang",
"Zhongyang",
""
],
[
"Yunes",
"Nicolas",
""
],
[
"Berti",
"Emanuele",
""
]
] | We study the effect of black hole spin on the accuracy of the post-Newtonian approximation. We focus on the gravitational energy flux for the quasicircular, equatorial, extreme mass-ratio inspiral of a compact object into a Kerr black hole of mass M and spin J. For a given dimensionless spin a=J/M^2 (in geometrical units), the energy flux depends only on the orbital velocity v or (equivalently) on the Boyer-Lindquist orbital radius r. We investigate the formal region of validity of the Taylor post-Newtonian expansion of the energy flux (which is known up to order v^8 beyond the quadrupole formula), generalizing previous work by two of us. The "error function" used to determine the region of validity of the post-Newtonian expansion can have two qualitatively different kinds of behavior, and we deal with these two cases separately. We find that, at any fixed post-Newtonian order, the edge of the region of validity (as measured by v/v_{ISCO}, where v_{ISCO} is the orbital velocity at the innermost stable circular orbit) is only weakly dependent on a. Unlike in the nonspinning case, the lack of sufficiently high order terms does not allow us to determine if there is a convergent to divergent transition at order v^6. Independently of a, the inclusion of angular multipoles up to and including l=5 in the numerical flux is necessary to achieve the level of accuracy of the best-known (N=8) PN expansion of the energy flux. |
gr-qc/0503060 | Wlodzimierz Piechocki | Jean-Pierre Gazeau, Marc Lachieze-Rey and Wlodzimierz Piechocki | On three quantization methods for particle on hyperboloid | 22 pages, no figures, revtex | null | null | null | gr-qc astro-ph hep-th quant-ph | null | We compare the respective efficiencies of three quantization methods (group
theoretical, coherent state and geometric) by quantizing the dynamics of a free
massive particle in two-dimensional de Sitter space. For each case we consider
the realization of the principal series representation of $SO_0(1,2) $ group
and its two-fold covering SU(1,1). We demonstrate that standard technique for
finding an irreducible representation within the geometric quantization scheme
fails. For consistency we recall our earlier results concerning the other two
methods, make some improvements and generalizations.
| [
{
"created": "Mon, 14 Mar 2005 14:31:27 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Mar 2005 13:43:21 GMT",
"version": "v2"
},
{
"created": "Tue, 3 Jan 2006 14:26:24 GMT",
"version": "v3"
}
] | 2007-05-23 | [
[
"Gazeau",
"Jean-Pierre",
""
],
[
"Lachieze-Rey",
"Marc",
""
],
[
"Piechocki",
"Wlodzimierz",
""
]
] | We compare the respective efficiencies of three quantization methods (group theoretical, coherent state and geometric) by quantizing the dynamics of a free massive particle in two-dimensional de Sitter space. For each case we consider the realization of the principal series representation of $SO_0(1,2) $ group and its two-fold covering SU(1,1). We demonstrate that standard technique for finding an irreducible representation within the geometric quantization scheme fails. For consistency we recall our earlier results concerning the other two methods, make some improvements and generalizations. |
1702.00969 | Maarten Van De Meent | Maarten van de Meent | The mass and angular momentum of reconstructed metric perturbations | Version accepted be CQG | Class.Quant.Grav. 34 (2017) no.12, 124003 | 10.1088/1361-6382/aa71c3 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We prove a key result regarding the mass and angular momentum content of
linear vacuum perturbations of the Kerr metric obtained through the formalism
developed by Chrzarnowski, Cohen, and Kegeles (CCK). More precisely we prove
that the Abbott-Deser mass and angular momentum integrals of any such
perturbation vanish, when that perturbation was obtained from a regular Fourier
mode of the Hertz potential. As a corollary we obtain a generalization of
previous results on the completion of the `no string' radiation gauge metric
perturbation generated by a point particle. We find that for any bound orbit
around a Kerr black hole, the mass and angular momentum perturbations
completing the CCK metric are simply the energy and angular momentum of the
particle "outside" the orbit and vanish "inside" the orbit.
| [
{
"created": "Fri, 3 Feb 2017 11:12:13 GMT",
"version": "v1"
},
{
"created": "Tue, 18 Jul 2017 13:00:47 GMT",
"version": "v2"
}
] | 2017-07-19 | [
[
"van de Meent",
"Maarten",
""
]
] | We prove a key result regarding the mass and angular momentum content of linear vacuum perturbations of the Kerr metric obtained through the formalism developed by Chrzarnowski, Cohen, and Kegeles (CCK). More precisely we prove that the Abbott-Deser mass and angular momentum integrals of any such perturbation vanish, when that perturbation was obtained from a regular Fourier mode of the Hertz potential. As a corollary we obtain a generalization of previous results on the completion of the `no string' radiation gauge metric perturbation generated by a point particle. We find that for any bound orbit around a Kerr black hole, the mass and angular momentum perturbations completing the CCK metric are simply the energy and angular momentum of the particle "outside" the orbit and vanish "inside" the orbit. |
gr-qc/0401067 | Alexandre Gavrilik | A.M. Gavrilik (BITP, Kiev) | Applying the q-algebras U'_q(so_n) to quantum gravity: towards
q-deformed analog of SO(n) spin networks | 6 pages (two-column), LaTeX, ujp.sty; talk given at the 13th Int.
Hutsulian Workshop "Methods of Theoretical and Mathematical Physics",
(September 2000, Kyiv, Ukraine) | Ukr.J.Phys. 47 (2002) 213-218 | null | null | gr-qc hep-th math-ph math.MP | null | Nonstandard q-deformed algebras U'_q(so_n), proposed a decade ago for the
needs of representation theory, essentially differ from the standard
Drinfeld-Jimbo quantum deformation of the algebras U(so_n) and possess with
regard to the latter a number of important advantages. We discuss possible
application of the q-algebras U'_q(so_n), within two different contexts of
quantum/q-deformed gravity: one concerns q-deforming of D-dimensional (D >= 3)
euclidean gravity, the other applies to 2+1 anti-De Sitter quantum gravity
(with space surface of genus g) in the approach of Nelson and Regge.
| [
{
"created": "Thu, 15 Jan 2004 19:19:57 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Gavrilik",
"A. M.",
"",
"BITP, Kiev"
]
] | Nonstandard q-deformed algebras U'_q(so_n), proposed a decade ago for the needs of representation theory, essentially differ from the standard Drinfeld-Jimbo quantum deformation of the algebras U(so_n) and possess with regard to the latter a number of important advantages. We discuss possible application of the q-algebras U'_q(so_n), within two different contexts of quantum/q-deformed gravity: one concerns q-deforming of D-dimensional (D >= 3) euclidean gravity, the other applies to 2+1 anti-De Sitter quantum gravity (with space surface of genus g) in the approach of Nelson and Regge. |
1906.03641 | Edward Anderson | Edward Anderson | A Local Resolution of the Problem of Time. VII. Constraint Closure | 23 pages including 7 figures. v2 improves concepts for, and
presentation of, our temporal-relationally modified Dirac Algorithm | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We now set up Constraint Closure in a manner consistent with Temporal and
Configurational Relationalism. This requires modifying the Dirac Algorithm -
which addresses the Constraint Closure Problem facet of the Problem of Time
piecemeal - to the TRi-Dirac Algorithm. This is a member of the wider class of
Dirac-type algorithms that enjoys the property of being Temporal Relationalism
implementing (TRi). Constraint algebraic structures ensue. We include examples
of types of constraint, outcomes of the Dirac Algorithm and different kinds of
Constraint Closure Problems. Enough new Principles of Dynamics is required to
support this venture that an Appendix on it is provided: differential
Hamiltonians, anti-Routhians, and the brackets, state spaces and morphisms
corresponding to these.
| [
{
"created": "Sun, 9 Jun 2019 13:37:57 GMT",
"version": "v1"
},
{
"created": "Tue, 9 Jul 2019 16:53:34 GMT",
"version": "v2"
}
] | 2019-07-10 | [
[
"Anderson",
"Edward",
""
]
] | We now set up Constraint Closure in a manner consistent with Temporal and Configurational Relationalism. This requires modifying the Dirac Algorithm - which addresses the Constraint Closure Problem facet of the Problem of Time piecemeal - to the TRi-Dirac Algorithm. This is a member of the wider class of Dirac-type algorithms that enjoys the property of being Temporal Relationalism implementing (TRi). Constraint algebraic structures ensue. We include examples of types of constraint, outcomes of the Dirac Algorithm and different kinds of Constraint Closure Problems. Enough new Principles of Dynamics is required to support this venture that an Appendix on it is provided: differential Hamiltonians, anti-Routhians, and the brackets, state spaces and morphisms corresponding to these. |
1709.09923 | Shahram Jalalzadeh | S. Jalalzadeh, A.J.S. Capistrano and P.V. Moniz | Quantum deformation of quantum cosmology: A framework to discuss the
cosmological constant problem | 14 pages, to appear in Physics of Dark Universe | Phys. Dark Universe, 18 (2017) 55 | 10.1016/j.dark.2017.09.011 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We endorse the context that the cosmological constant problem is a quantum
cosmology issue. Therefore, in this paper we investigate the $q$-deformed
Wheeler-DeWitt equation of a spatially closed homogeneous and isotropic
Universe in the presence of a conformally coupled scalar field. Specifically,
the quantum deformed Universe is a quantized minisuperspace model constructed
from quantum Heisenberg-Weyl $\mathcal U_q(h_4)$ and $\mathcal U_q(su(1, 1))$
groups. These intrinsic mathematical features allow to establish that ($i$) the
scale factor, the scalar field and corresponding momenta are quantized and
($ii$) the phase space has a non-equidistance lattice structure. On the other
hand, such quantum group structure provides us a new framework to discuss the
cosmological constant problem. Subsequently, we show that a ultraviolet cutoff
can be obtained at $10^{-3} eV$, i.e., at a scale much larger than the expected
Planck scale. In addition, an infrared cutoff, at the size of the observed
Universe, emerges from within such quantum deformation of Universe. In other
words, the spectrum of the scale factor is upper bounded. Moreover, we show
that the emerged cosmological horizon is a quantum sphere $S^2_q$ or,
alternatively, a fuzzy sphere $S^2_F$ which explicitly exhibits features of the
holographic principle. The corresponding number of fundamental cells equals the
dimension of the Hilbert space and hence, the cosmological constant can be
presented as a consequence of the quantum deformation of the FLRW
minisuperspace.
| [
{
"created": "Thu, 28 Sep 2017 12:43:32 GMT",
"version": "v1"
}
] | 2023-05-02 | [
[
"Jalalzadeh",
"S.",
""
],
[
"Capistrano",
"A. J. S.",
""
],
[
"Moniz",
"P. V.",
""
]
] | We endorse the context that the cosmological constant problem is a quantum cosmology issue. Therefore, in this paper we investigate the $q$-deformed Wheeler-DeWitt equation of a spatially closed homogeneous and isotropic Universe in the presence of a conformally coupled scalar field. Specifically, the quantum deformed Universe is a quantized minisuperspace model constructed from quantum Heisenberg-Weyl $\mathcal U_q(h_4)$ and $\mathcal U_q(su(1, 1))$ groups. These intrinsic mathematical features allow to establish that ($i$) the scale factor, the scalar field and corresponding momenta are quantized and ($ii$) the phase space has a non-equidistance lattice structure. On the other hand, such quantum group structure provides us a new framework to discuss the cosmological constant problem. Subsequently, we show that a ultraviolet cutoff can be obtained at $10^{-3} eV$, i.e., at a scale much larger than the expected Planck scale. In addition, an infrared cutoff, at the size of the observed Universe, emerges from within such quantum deformation of Universe. In other words, the spectrum of the scale factor is upper bounded. Moreover, we show that the emerged cosmological horizon is a quantum sphere $S^2_q$ or, alternatively, a fuzzy sphere $S^2_F$ which explicitly exhibits features of the holographic principle. The corresponding number of fundamental cells equals the dimension of the Hilbert space and hence, the cosmological constant can be presented as a consequence of the quantum deformation of the FLRW minisuperspace. |
2311.13300 | Hai-Tian Wang | Hai-Tian Wang and Lijing Shao | Effect of Noise Estimation in Time-Domain Ringdown Analysis: A Case
Study with GW150914 | 6 pages, 4 figures. Accepted by PRD | Phys. Rev. D 108 (2023) 123018 | 10.1103/PhysRevD.108.123018 | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Accurate noise estimation from gravitational wave (GW) data is critical for
Bayesian inference. However, recent studies on ringdown signal, such as those
by Isi et al. [1], Cotesta et al. [2], and Isi and Farr [3], have encountered
disagreement in noise estimation, leading to inconsistent results. The key
discrepancy between these studies lies in the usage of different noise
estimation methods, augmented by the usage of different sampling rates. We
achieved consistent results across various sampling rates by correctly managing
noise estimation, shown in the case study of the GW150914 ringdown signal. By
conducting a time-domain Bayesian inference analysis on GW data, starting from
the peak of the signal, we discovered that the first overtone mode is weakly
supported by the amplitude distribution, with a confidence level of
$1.6{\sigma}$, and is slightly disfavored by the log-Bayes factor. Overall, in
our time-domain analysis we conclude there is no strong evidence for overtones
in GW150914.
| [
{
"created": "Wed, 22 Nov 2023 10:43:58 GMT",
"version": "v1"
}
] | 2023-12-22 | [
[
"Wang",
"Hai-Tian",
""
],
[
"Shao",
"Lijing",
""
]
] | Accurate noise estimation from gravitational wave (GW) data is critical for Bayesian inference. However, recent studies on ringdown signal, such as those by Isi et al. [1], Cotesta et al. [2], and Isi and Farr [3], have encountered disagreement in noise estimation, leading to inconsistent results. The key discrepancy between these studies lies in the usage of different noise estimation methods, augmented by the usage of different sampling rates. We achieved consistent results across various sampling rates by correctly managing noise estimation, shown in the case study of the GW150914 ringdown signal. By conducting a time-domain Bayesian inference analysis on GW data, starting from the peak of the signal, we discovered that the first overtone mode is weakly supported by the amplitude distribution, with a confidence level of $1.6{\sigma}$, and is slightly disfavored by the log-Bayes factor. Overall, in our time-domain analysis we conclude there is no strong evidence for overtones in GW150914. |
gr-qc/9505050 | Luanne Neumann | G.F. Chew | Testing Single-Parameter Classical Standpoint Cosmology | 27 pages, latexed, math_macros.tex used, full postscript available
from: http://theor1.lbl.gov/www/theorgroup/papers/37162.ps | null | null | LBL-37162 | gr-qc | null | Experimental tests of homogeneous-universe classical standpoint cosmology are
proposed after presentation of conceptual considerations that encourage this
radical departure from the standard model. Among predictions of the new model
are standpoint age equal to Hubble time, energy-density parameter $\Omega_0 = 2
- \sqrt{2} =.586$, and relations between redshift, Hubble-scale distribution of
matter and galaxy luminosity and angular diameter. These latter relations
coincide with those of the standard model for zero deceleration. With eye to
further tests, geodesics of the non-Riemannian standpoint metric are explicitly
given. Although a detailed thermodynamic ``youthful-standpoint'' approximation
remains to be developed (for particle mean free path small on standpoint
scale), standpoint temperature depending only on standpoint age is a natural
concept, paralleling energy density and redshift that perpetuates thermal
spectrum for cosmic background radiation. Prospects for primordial
nucleosynthesis are promising.
| [
{
"created": "Tue, 30 May 1995 17:49:27 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Chew",
"G. F.",
""
]
] | Experimental tests of homogeneous-universe classical standpoint cosmology are proposed after presentation of conceptual considerations that encourage this radical departure from the standard model. Among predictions of the new model are standpoint age equal to Hubble time, energy-density parameter $\Omega_0 = 2 - \sqrt{2} =.586$, and relations between redshift, Hubble-scale distribution of matter and galaxy luminosity and angular diameter. These latter relations coincide with those of the standard model for zero deceleration. With eye to further tests, geodesics of the non-Riemannian standpoint metric are explicitly given. Although a detailed thermodynamic ``youthful-standpoint'' approximation remains to be developed (for particle mean free path small on standpoint scale), standpoint temperature depending only on standpoint age is a natural concept, paralleling energy density and redshift that perpetuates thermal spectrum for cosmic background radiation. Prospects for primordial nucleosynthesis are promising. |
gr-qc/0203041 | Stoytcho Yazadjiev | Stoytcho S. Yazadjiev (Sofia University) | Geodesically complete nondiagonal inhomogeneous cosmological solutions
in dilatonic gravity with a stiff perfect fluid | 11 pages, Revtex; v2 improvements, references and acknowledgments
added; v3 comments, references and acknowledgments added, Phys. Rev. D in
press | Phys.Rev. D66 (2002) 024031 | 10.1103/PhysRevD.66.024031 | null | gr-qc astro-ph hep-th | null | New nondiagonal $G_{2}$ inhomogeneous cosmological solutions are presented in
a wide range of scalar-tensor theories with a stiff perfect fluid as a matter
source. The solutions have no big-bang singularity or any other curvature
singularities. The dilaton field and the fluid energy density are everywhere
regular, too. The geodesic completeness of the solutions is investigated.
| [
{
"created": "Tue, 12 Mar 2002 17:08:53 GMT",
"version": "v1"
},
{
"created": "Thu, 28 Mar 2002 11:12:43 GMT",
"version": "v2"
},
{
"created": "Thu, 4 Jul 2002 07:11:20 GMT",
"version": "v3"
}
] | 2009-11-07 | [
[
"Yazadjiev",
"Stoytcho S.",
"",
"Sofia University"
]
] | New nondiagonal $G_{2}$ inhomogeneous cosmological solutions are presented in a wide range of scalar-tensor theories with a stiff perfect fluid as a matter source. The solutions have no big-bang singularity or any other curvature singularities. The dilaton field and the fluid energy density are everywhere regular, too. The geodesic completeness of the solutions is investigated. |
2007.03050 | Eric Poisson | Eric Poisson and Cyann Buisson | Tidal driving of inertial modes of Maclaurin spheroids | 28 pages, 7 figures, revised after referee comments, new Appendix,
matches published version | Phys. Rev. D 102, 104005 (2020) | 10.1103/PhysRevD.102.104005 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We examine the inertial modes of vibration of a Maclaurin spheroid and
determine how they are driven by an external tidal field, either Newtonian
(gravitoelectric) or post-Newtonian (gravitomagnetic). The context and
motivation for this work come from the realization that inertial modes of
rotating neutron stars can be resonantly excited in binary inspirals, with a
measurable effect on the phasing of the emitted gravitational waves. We aim to
provide additional insights into this phenomenon. We calculate how the
frequencies of the relevant inertial modes, and their overlap integrals with
the tidal forces, vary as the star's rotation rate increases, spanning almost
the full range between zero rotation and the mass-shedding limit. We prove that
a single inertial mode couples to a Newtonian tidal field; overlap integrals
with all other modes vanish. We prove also that four inertial modes couple to a
post-Newtonian, gravitomagnetic tidal field; overlap integrals with all other
modes vanish. Finally, we determine the rather extreme conditions under which
the gravitoelectric driving of inertial modes dominates over the
gravitomagnetic driving.
| [
{
"created": "Mon, 6 Jul 2020 20:23:40 GMT",
"version": "v1"
},
{
"created": "Fri, 23 Oct 2020 12:20:38 GMT",
"version": "v2"
}
] | 2020-11-11 | [
[
"Poisson",
"Eric",
""
],
[
"Buisson",
"Cyann",
""
]
] | We examine the inertial modes of vibration of a Maclaurin spheroid and determine how they are driven by an external tidal field, either Newtonian (gravitoelectric) or post-Newtonian (gravitomagnetic). The context and motivation for this work come from the realization that inertial modes of rotating neutron stars can be resonantly excited in binary inspirals, with a measurable effect on the phasing of the emitted gravitational waves. We aim to provide additional insights into this phenomenon. We calculate how the frequencies of the relevant inertial modes, and their overlap integrals with the tidal forces, vary as the star's rotation rate increases, spanning almost the full range between zero rotation and the mass-shedding limit. We prove that a single inertial mode couples to a Newtonian tidal field; overlap integrals with all other modes vanish. We prove also that four inertial modes couple to a post-Newtonian, gravitomagnetic tidal field; overlap integrals with all other modes vanish. Finally, we determine the rather extreme conditions under which the gravitoelectric driving of inertial modes dominates over the gravitomagnetic driving. |
2001.02038 | Junji Jia | Junji Jia | The perturbative approach for the weak deflection angle | 42 pages, 5 figures; typos and grammar corrected; references added; | null | 10.1140/epjc/s10052-020-7796-y | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Both null and timelike rays experience trajectory bending in a gravitational
field. In this work, we systematically develop a perturbative method to compute
the deflection angle of rays with general velocity $v$ in arbitrary static and
spherically symmetric spacetimes and in equatorial plane of arbitrary static
and axisymmetric spacetimes. We show that the expansion in the large closest
approach $x_0$ limit depends on the asymptotic behavior of the metric functions
only, and the generated integrand is always integrable, resulting in a
deflection angle in a series form of either $x_0$ or $b$, the impact parameter.
Using this method, the deflection angles as series of both $x_0$ and $b$ are
found in Schwarzschild, Reissner-Nordstr\"{o}m and Kerr-Newman spacetimes to
17-th, 15-th and 6-th orders respectively, for both lightrays and particles
with general velocity. The effects of the impact parameter, velocity and other
parameters of the spacatimes are briefly analyzed. Moreover, we show that for
spacetimes whose metric functions are only asymptotically known, the deflection
angle in the weak field limit can also be calculated. Furthermore, it is shown
that the deflection angle in general static and spherically symmetric spacetime
and equatorial plane of static and axisymmetric spacetime to the lowest
non-trivial order, depends only on the impact parameter, velocity of the
particle, and the effective ADM mass of the spacetime but not on other
parameters such as charge or angular momentum. These deflection angles are used
in an exact gravitational lensing equation and the corresponding apparent
angles of the images of the source are also solved perturbatively.
| [
{
"created": "Tue, 7 Jan 2020 14:08:13 GMT",
"version": "v1"
},
{
"created": "Wed, 8 Jan 2020 17:13:41 GMT",
"version": "v2"
},
{
"created": "Tue, 18 Feb 2020 00:07:04 GMT",
"version": "v3"
}
] | 2020-04-22 | [
[
"Jia",
"Junji",
""
]
] | Both null and timelike rays experience trajectory bending in a gravitational field. In this work, we systematically develop a perturbative method to compute the deflection angle of rays with general velocity $v$ in arbitrary static and spherically symmetric spacetimes and in equatorial plane of arbitrary static and axisymmetric spacetimes. We show that the expansion in the large closest approach $x_0$ limit depends on the asymptotic behavior of the metric functions only, and the generated integrand is always integrable, resulting in a deflection angle in a series form of either $x_0$ or $b$, the impact parameter. Using this method, the deflection angles as series of both $x_0$ and $b$ are found in Schwarzschild, Reissner-Nordstr\"{o}m and Kerr-Newman spacetimes to 17-th, 15-th and 6-th orders respectively, for both lightrays and particles with general velocity. The effects of the impact parameter, velocity and other parameters of the spacatimes are briefly analyzed. Moreover, we show that for spacetimes whose metric functions are only asymptotically known, the deflection angle in the weak field limit can also be calculated. Furthermore, it is shown that the deflection angle in general static and spherically symmetric spacetime and equatorial plane of static and axisymmetric spacetime to the lowest non-trivial order, depends only on the impact parameter, velocity of the particle, and the effective ADM mass of the spacetime but not on other parameters such as charge or angular momentum. These deflection angles are used in an exact gravitational lensing equation and the corresponding apparent angles of the images of the source are also solved perturbatively. |
gr-qc/0203105 | Guillermo F. Rubilar | Friedrich W. Hehl, Yuri N. Obukhov and Guillermo F. Rubilar | Light propagation in generally covariant electrodynamics and the Fresnel
equation | 6 pages, uses ws-ijmpa.cls. Invited talk given at Journees
Relativistes, University College Dublin, Sept. 2001. Will appear in
Int.J.Mod.Phys.A | Int.J.Mod.Phys. A17 (2002) 2695-2700 | 10.1142/S0217751X0201162X | null | gr-qc hep-th | null | Within the framework of generally covariant (pre-metric) electrodynamics, we
specify a local vacuum spacetime relation between the excitation $H=({\cal
D},{\cal H})$ and the field strength $F=(E,B)$. We study the propagation of
electromagnetic waves in such a spacetime by Hadamard's method and arrive, with
the constitutive tensor density $\kappa\sim\partial H/\partial F$, at a Fresnel
equation which is algebraic of 4th order in the wave covector. We determine how
the different pieces of $\kappa$, in particular the axion and the skewon
pieces, affect the propagation of light.
| [
{
"created": "Thu, 28 Mar 2002 15:38:20 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Hehl",
"Friedrich W.",
""
],
[
"Obukhov",
"Yuri N.",
""
],
[
"Rubilar",
"Guillermo F.",
""
]
] | Within the framework of generally covariant (pre-metric) electrodynamics, we specify a local vacuum spacetime relation between the excitation $H=({\cal D},{\cal H})$ and the field strength $F=(E,B)$. We study the propagation of electromagnetic waves in such a spacetime by Hadamard's method and arrive, with the constitutive tensor density $\kappa\sim\partial H/\partial F$, at a Fresnel equation which is algebraic of 4th order in the wave covector. We determine how the different pieces of $\kappa$, in particular the axion and the skewon pieces, affect the propagation of light. |
2111.13739 | Adri\'an Francisco Eduarte-Rojas | Adri\'an Francisco Eduarte-Rojas, Francisco Frutos-Alfaro, Rodrigo
Carboni and Daniel Alvarado | Chaotic Behavior of Geodesics in Kerr-like Spacetime | 30 pages, 32 figures | null | 10.1103/PhysRevD.106.064015 | null | gr-qc nlin.CD | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this contribution, the motion of unitary mass test particles in a
perturbed Kerr-like metric is studied using simulations in the configuration
and phase space. Our metric represents the approximate exterior spacetime of a
massive rotating body with mass quadrupole moment $q$. Chaotic behavior arises
as the $q$ parameter increases. The rotation number is determined for an axis
of symmetry in the corresponding Poincar\'e section. The existence of chaotic
regions in the region near the source event horizon is shown.
| [
{
"created": "Fri, 26 Nov 2021 20:28:51 GMT",
"version": "v1"
}
] | 2022-09-21 | [
[
"Eduarte-Rojas",
"Adrián Francisco",
""
],
[
"Frutos-Alfaro",
"Francisco",
""
],
[
"Carboni",
"Rodrigo",
""
],
[
"Alvarado",
"Daniel",
""
]
] | In this contribution, the motion of unitary mass test particles in a perturbed Kerr-like metric is studied using simulations in the configuration and phase space. Our metric represents the approximate exterior spacetime of a massive rotating body with mass quadrupole moment $q$. Chaotic behavior arises as the $q$ parameter increases. The rotation number is determined for an axis of symmetry in the corresponding Poincar\'e section. The existence of chaotic regions in the region near the source event horizon is shown. |
gr-qc/9408035 | Kumar Shwetketu Virbhadra | K. S. Virbhadra | Exact solutions of Einstein and Einstein-scalar equations in 2 + 1
dimensions | 8 pages, Latex, no number | Pramana 44 (1995) 317-322 | 10.1007/BF02847608 | null | gr-qc hep-th | null | A nonstatic and circularly symmetric exact solution of the Einstein equations
(with a cosmological constant $\Lambda$ and null fluid) in $2+1$ dimensions is
given. This is a nonstatic generalization of the uncharged spinless BTZ metric.
For $\Lambda = 0 $, the spacetime is though not flat, the Kretschmann invariant
vanishes. The energy, momentum, and power output for this metric are obtained.
Further a static and circularly symmetric exact solution of the
Einstein-massless scalar equations is given, which has a curvature singularity
at $r =0$ and the scalar field diverges at $r=0$ as well as at infinity .
| [
{
"created": "Mon, 29 Aug 1994 14:42:00 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Virbhadra",
"K. S.",
""
]
] | A nonstatic and circularly symmetric exact solution of the Einstein equations (with a cosmological constant $\Lambda$ and null fluid) in $2+1$ dimensions is given. This is a nonstatic generalization of the uncharged spinless BTZ metric. For $\Lambda = 0 $, the spacetime is though not flat, the Kretschmann invariant vanishes. The energy, momentum, and power output for this metric are obtained. Further a static and circularly symmetric exact solution of the Einstein-massless scalar equations is given, which has a curvature singularity at $r =0$ and the scalar field diverges at $r=0$ as well as at infinity . |
1012.0241 | Evgeny Novikov | S. G. Chefranov, E. A. Novikov | Hydrodynamic Vacuum Sources of Dark Matter Self-Generation in
Accelerated Universe without Big Bang | 22 pages, 1 figure | Zh.Eksp.Teor.Fiz.138:830-843,2010;
J.Exp.Theor.Phys.111:731-743,2010 | 10.1134/S106377611011004X | null | gr-qc astro-ph.CO physics.flu-dyn physics.gen-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We have obtained a generalization of the hydrodynamic theory of vacuum in the
context of general relativity. While retaining the Lagrangian character of
general relativity, the new theory provides a natural alternative to the view
that the singularity is inevitable in general relativity and in the theory of a
hot Universe. We show that the macroscopic source-sink motion of the ordinary
(dark) matter during production-absorption of particles by vacuum generates
polarization (determining the variability of the cosmological term in general
relativity). We have removed the well-known problems of the cosmological
constant by refining the physical nature of dark energy associated precisely
with this hydrodynamically initiated variability of the vacuum energy density.
A new exact solution of the modified general relativity equations that contains
no free (fitting) parameter (additional to thouse available in general
relativity) has been obtained. It corresponds to continuous and
metric-affecting production of ultralight dark matter particles out of vacuum,
with its density being retaned constant during the expansion of spatially flat
Universe. This solution is shown to be stable in the regime of cosmological
expansion untill Tmax about 38 billion years. After that time, the solution
becomes unstable and characterizes the inverse process of dark matter particles
absorption by the vacuum in the regime of contraction of the Universe. The
physical nature of dark matter particles is considered and their mass is
estimated. Good quantitative agreement of the indicated exact solution with
cosmological observations (SnIa, SDSS-BAO and recently found reduction of
acceleration of the expanding Universe) has been obtained.
| [
{
"created": "Tue, 30 Nov 2010 02:33:52 GMT",
"version": "v1"
}
] | 2011-01-27 | [
[
"Chefranov",
"S. G.",
""
],
[
"Novikov",
"E. A.",
""
]
] | We have obtained a generalization of the hydrodynamic theory of vacuum in the context of general relativity. While retaining the Lagrangian character of general relativity, the new theory provides a natural alternative to the view that the singularity is inevitable in general relativity and in the theory of a hot Universe. We show that the macroscopic source-sink motion of the ordinary (dark) matter during production-absorption of particles by vacuum generates polarization (determining the variability of the cosmological term in general relativity). We have removed the well-known problems of the cosmological constant by refining the physical nature of dark energy associated precisely with this hydrodynamically initiated variability of the vacuum energy density. A new exact solution of the modified general relativity equations that contains no free (fitting) parameter (additional to thouse available in general relativity) has been obtained. It corresponds to continuous and metric-affecting production of ultralight dark matter particles out of vacuum, with its density being retaned constant during the expansion of spatially flat Universe. This solution is shown to be stable in the regime of cosmological expansion untill Tmax about 38 billion years. After that time, the solution becomes unstable and characterizes the inverse process of dark matter particles absorption by the vacuum in the regime of contraction of the Universe. The physical nature of dark matter particles is considered and their mass is estimated. Good quantitative agreement of the indicated exact solution with cosmological observations (SnIa, SDSS-BAO and recently found reduction of acceleration of the expanding Universe) has been obtained. |
0803.2855 | Enore Guadagnini | E. Guadagnini | Gravitons scattering from classical matter | 15 pages, 3 figures, to be published in Classical and Quantum Gravity | Class.Quant.Grav.25:095012,2008 | 10.1088/0264-9381/25/9/095012 | IFUP-TH/2008-07 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The low energy scattering of gravitons from a composite extended system,
which is made of classical massive bodies, is considered; by using the Feynman
rules of effective quantum gravity, the corresponding cross-section is computed
to lowest order in powers of the gravitational coupling constant. For the
gravitons scattering from a rotating planet or a star, it is shown that the
classical limit of the matter-gravitons coupling in the effective quantum
gravity lagrangian leads to a low energy scattering amplitude which coincides
with the expression obtained in classical general relativity.
| [
{
"created": "Wed, 19 Mar 2008 17:58:30 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Guadagnini",
"E.",
""
]
] | The low energy scattering of gravitons from a composite extended system, which is made of classical massive bodies, is considered; by using the Feynman rules of effective quantum gravity, the corresponding cross-section is computed to lowest order in powers of the gravitational coupling constant. For the gravitons scattering from a rotating planet or a star, it is shown that the classical limit of the matter-gravitons coupling in the effective quantum gravity lagrangian leads to a low energy scattering amplitude which coincides with the expression obtained in classical general relativity. |
2102.01831 | Matt Visser | Aden Jowsey (Victoria University of Wellington) and Matt Visser
(Victoria University of Wellington) | Counterexamples to the maximum force conjecture | V1: 29 pages; 6 figures; V2: minor typos fixed | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Dimensional analysis shows that the speed of light and Newton's constant of
gravitation can be combined to define a quantity $F_* = {c^4\over G_N}$ with
the dimensions of force (equivalently, tension). Then in any physical situation
we must have $F_{physical} = f \; F_*$, where the quantity $f$ is some
dimensionless function of dimensionless parameters. In many physical situations
explicit calculation yields $f= O(1)$, and quite often $f \leq {1\over4}$. This
has lead multiple authors to suggest a (weak or strong) maximum force/maximum
tension conjecture. Working within the framework of standard general
relativity, we will instead focus on counter-examples to this conjecture,
paying particular attention to the extent to which the counter-examples are
physically reasonable. The various counter-examples we shall explore strongly
suggest that one should not put too much credence into any universal maximum
force/maximum tension conjecture. Specifically, fluid spheres on the verge of
gravitational collapse will generically violate the weak (and strong) maximum
force conjectures. If one wishes to retain any general notion of "maximum
force" then one will have to very carefully specify precisely which forces are
to be allowed within the domain of discourse.
| [
{
"created": "Wed, 3 Feb 2021 01:41:19 GMT",
"version": "v1"
},
{
"created": "Tue, 2 Mar 2021 06:38:06 GMT",
"version": "v2"
}
] | 2021-03-03 | [
[
"Jowsey",
"Aden",
"",
"Victoria University of Wellington"
],
[
"Visser",
"Matt",
"",
"Victoria University of Wellington"
]
] | Dimensional analysis shows that the speed of light and Newton's constant of gravitation can be combined to define a quantity $F_* = {c^4\over G_N}$ with the dimensions of force (equivalently, tension). Then in any physical situation we must have $F_{physical} = f \; F_*$, where the quantity $f$ is some dimensionless function of dimensionless parameters. In many physical situations explicit calculation yields $f= O(1)$, and quite often $f \leq {1\over4}$. This has lead multiple authors to suggest a (weak or strong) maximum force/maximum tension conjecture. Working within the framework of standard general relativity, we will instead focus on counter-examples to this conjecture, paying particular attention to the extent to which the counter-examples are physically reasonable. The various counter-examples we shall explore strongly suggest that one should not put too much credence into any universal maximum force/maximum tension conjecture. Specifically, fluid spheres on the verge of gravitational collapse will generically violate the weak (and strong) maximum force conjectures. If one wishes to retain any general notion of "maximum force" then one will have to very carefully specify precisely which forces are to be allowed within the domain of discourse. |
gr-qc/0608031 | Nikodem Poplawski | Nikodem J. Poplawski | A Lagrangian description of interacting dark energy | 14 pages; corrected errors, added comments | null | null | null | gr-qc astro-ph hep-th | null | We propose a relativistically covariant model of interacting dark energy
based on the principle of least action. The cosmological term $\Lambda$ in the
gravitational Lagrangian is a function of the trace of the energy--momentum
tensor $T$. We find that the $\Lambda(T)$ gravity is more general than the
Palatini $f(R)$ gravity, and reduces to the latter if we neglect the pressure
of matter. We show that recent cosmological data favor a variable cosmological
constant and are consistent with the $\Lambda(T)$ gravity, without knowing the
specific function $\Lambda(T)$.
| [
{
"created": "Mon, 7 Aug 2006 02:32:43 GMT",
"version": "v1"
},
{
"created": "Mon, 25 Sep 2006 03:01:02 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Poplawski",
"Nikodem J.",
""
]
] | We propose a relativistically covariant model of interacting dark energy based on the principle of least action. The cosmological term $\Lambda$ in the gravitational Lagrangian is a function of the trace of the energy--momentum tensor $T$. We find that the $\Lambda(T)$ gravity is more general than the Palatini $f(R)$ gravity, and reduces to the latter if we neglect the pressure of matter. We show that recent cosmological data favor a variable cosmological constant and are consistent with the $\Lambda(T)$ gravity, without knowing the specific function $\Lambda(T)$. |
2105.03730 | Mehdi Vatandoost | Mehdi Vatandoost, Rahimeh Pourkhandani and Neda Ebrahimi | Causally simple spacetimes and naked singularities | null | null | null | null | gr-qc math-ph math.DG math.MP | http://creativecommons.org/licenses/by-nc-nd/4.0/ | In this paper, We prove a conjecture which states that if M is a nakedly
singular future boundary or nakedly singular past boundary spacetime, then the
space of null geodesics, N, is non-Hausdorff. Also, we show that every
two-dimensional strongly causal spacetime M is causally simple if and only if
it is null pseudoconvex. As a result, it implies the converse of the conjecture
for two-dimension but there are examples that refute it for more dimensions.
| [
{
"created": "Sat, 8 May 2021 16:23:10 GMT",
"version": "v1"
}
] | 2021-05-11 | [
[
"Vatandoost",
"Mehdi",
""
],
[
"Pourkhandani",
"Rahimeh",
""
],
[
"Ebrahimi",
"Neda",
""
]
] | In this paper, We prove a conjecture which states that if M is a nakedly singular future boundary or nakedly singular past boundary spacetime, then the space of null geodesics, N, is non-Hausdorff. Also, we show that every two-dimensional strongly causal spacetime M is causally simple if and only if it is null pseudoconvex. As a result, it implies the converse of the conjecture for two-dimension but there are examples that refute it for more dimensions. |
2110.06867 | Griselda Figueroa Aguirre | Cecilia Bejarano, Ernesto F. Eiroa, Griselda Figueroa-Aguirre | Circularly symmetric thin-shell wormholes in F(R) gravity with
(2+1)-dimensions | 8 pages, 2 figures; prepared for the Proceedings of the Sixteenth
Marcel Grossmann Meeting - MG16 | Proceedings of the Sixteenth Marcel Grossmann Meeting (MG16),
pages 831-839 (World Scientific, Singapore, 2023) | 10.1142/9789811269776_0065 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Within the framework of $F(R)$ theories of gravity with (2+1)-dimensions and
constant scalar curvature $R$, we construct a family of thin-shell wormholes
with circular symmetry and we analyze the stability of the static
configurations under radial perturbations. We show an example of asymptotically
anti-de Sitter thin-shell wormholes with charge, finding that stable
configurations with normal matter are possible for a suitable range of the
parameters.
| [
{
"created": "Wed, 13 Oct 2021 17:03:31 GMT",
"version": "v1"
}
] | 2023-01-31 | [
[
"Bejarano",
"Cecilia",
""
],
[
"Eiroa",
"Ernesto F.",
""
],
[
"Figueroa-Aguirre",
"Griselda",
""
]
] | Within the framework of $F(R)$ theories of gravity with (2+1)-dimensions and constant scalar curvature $R$, we construct a family of thin-shell wormholes with circular symmetry and we analyze the stability of the static configurations under radial perturbations. We show an example of asymptotically anti-de Sitter thin-shell wormholes with charge, finding that stable configurations with normal matter are possible for a suitable range of the parameters. |
2303.16924 | Hong Lu | Zhi-Chao Li and H. Lu | Regular Black Holes and Stars from Analytic $f(F^2)$ | Latex, 28 pages, 2 plots grouped into one figure, typos corrected,
references added, further discussions on electrically-charged regular black
holes, new references added, a new self-dual NLED added | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct regular black holes and stars that are geodesically complete and
satisfy the dominant energy condition from Einstein-$f(F^2)$ gravities with
several classes of analytic $f(F^2)$ functions that can be viewed as
perturbations to Maxwell's theory in weak field limit. We establish that
regular black holes with special static metric ($g_{tt} g_{rr}=-1$) violate the
strong energy condition and such a regular black hole with Minkowski core
violates the null energy condition. We develop a formalism to perform
electromagnetic duality transformations in $f(F^2)$. We obtain two new explicit
examples where the duality is a symmetry. We study the properties of the
corresponding dyonic black holes. We study the geodesic motions of a particular
class of solutions that we call repulson stars or black holes.
| [
{
"created": "Wed, 29 Mar 2023 18:00:01 GMT",
"version": "v1"
},
{
"created": "Thu, 6 Apr 2023 11:42:33 GMT",
"version": "v2"
},
{
"created": "Tue, 11 Apr 2023 11:59:29 GMT",
"version": "v3"
}
] | 2023-04-12 | [
[
"Li",
"Zhi-Chao",
""
],
[
"Lu",
"H.",
""
]
] | We construct regular black holes and stars that are geodesically complete and satisfy the dominant energy condition from Einstein-$f(F^2)$ gravities with several classes of analytic $f(F^2)$ functions that can be viewed as perturbations to Maxwell's theory in weak field limit. We establish that regular black holes with special static metric ($g_{tt} g_{rr}=-1$) violate the strong energy condition and such a regular black hole with Minkowski core violates the null energy condition. We develop a formalism to perform electromagnetic duality transformations in $f(F^2)$. We obtain two new explicit examples where the duality is a symmetry. We study the properties of the corresponding dyonic black holes. We study the geodesic motions of a particular class of solutions that we call repulson stars or black holes. |
1411.3661 | Suddhasattwa Brahma | Suddhasattwa Brahma | Spherically symmetric canonical quantum gravity | 21 pages; minor corrections and additional references | Phys. Rev. D 91, 124003 (2015) | 10.1103/PhysRevD.91.124003 | IGC-14/11-1 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Canonical quantization of spherically symmetric space-times is carried out,
using real-valued densitized triads and extrinsic curvature components, with
specific factor ordering choices ensuring in an anomaly free quantum constraint
algebra. Comparison with previous work [1] reveals that the resulting physical
Hilbert space has the same form, although the basic canonical variables are
different in the two approaches. As an extension, holonomy modifications from
Loop Quantum Gravity are shown to deform the Dirac space-time algebra, while
going beyond `effective' calculations.
| [
{
"created": "Thu, 13 Nov 2014 18:51:04 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Jun 2015 01:20:14 GMT",
"version": "v2"
}
] | 2015-06-05 | [
[
"Brahma",
"Suddhasattwa",
""
]
] | Canonical quantization of spherically symmetric space-times is carried out, using real-valued densitized triads and extrinsic curvature components, with specific factor ordering choices ensuring in an anomaly free quantum constraint algebra. Comparison with previous work [1] reveals that the resulting physical Hilbert space has the same form, although the basic canonical variables are different in the two approaches. As an extension, holonomy modifications from Loop Quantum Gravity are shown to deform the Dirac space-time algebra, while going beyond `effective' calculations. |
0706.2933 | Alfredo L\'opez Ortega | A. L\'opez-Ortega | Electromagnetic quasinormal modes of D-dimensional black holes II | 34 pages, 14 figures, 6 tables | Gen.Rel.Grav.40:1379-1401,2008 | 10.1007/s10714-007-0538-8 | null | gr-qc | null | By using the sixth order WKB approximation we calculate for an
electromagnetic field propagating in D-dimensional Schwarzschild and
Schwarzschild de Sitter black holes its quasinormal frequencies for the
fundamental mode and first overtones. We study the dependence of these QN
frequencies on the value of the cosmological constant and the spacetime
dimension. We also compare with the known results for the gravitational
perturbations propagating in the same background. Moreover we exactly compute
the QN frequencies of the electromagnetic field propagating in D-dimensional
massless topological black hole and for charged D-dimensional Nariai spacetime
we exactly calculate the QN frequencies of the coupled electromagnetic and
gravitational perturbations.
| [
{
"created": "Wed, 20 Jun 2007 08:04:55 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"López-Ortega",
"A.",
""
]
] | By using the sixth order WKB approximation we calculate for an electromagnetic field propagating in D-dimensional Schwarzschild and Schwarzschild de Sitter black holes its quasinormal frequencies for the fundamental mode and first overtones. We study the dependence of these QN frequencies on the value of the cosmological constant and the spacetime dimension. We also compare with the known results for the gravitational perturbations propagating in the same background. Moreover we exactly compute the QN frequencies of the electromagnetic field propagating in D-dimensional massless topological black hole and for charged D-dimensional Nariai spacetime we exactly calculate the QN frequencies of the coupled electromagnetic and gravitational perturbations. |
gr-qc/0004031 | Jiri Bicak | Jiri Bicak | Exact radiative spacetimes: some recent developments | 10 pages, Invited talk, Journees Relativiste 1999 | Annalen Phys.9:207-216,2000 | 10.1002/(SICI)1521-3889(200005)9:3/5<207::AID-ANDP207>3.0.CO;2-L | null | gr-qc astro-ph hep-th | null | Five classes of radiative solutions of Einstein's field equations are
discussed in the light of some new developments. These are plane waves and
their collisions, cylindrical waves, Robinson-Trautman and type N spacetimes,
boost-rotation symmetric spacetimes and generalized Gowdy-type cosmological
models
| [
{
"created": "Mon, 10 Apr 2000 17:03:11 GMT",
"version": "v1"
}
] | 2017-09-27 | [
[
"Bicak",
"Jiri",
""
]
] | Five classes of radiative solutions of Einstein's field equations are discussed in the light of some new developments. These are plane waves and their collisions, cylindrical waves, Robinson-Trautman and type N spacetimes, boost-rotation symmetric spacetimes and generalized Gowdy-type cosmological models |
1105.0122 | Bruno Giacomazzo | Bruno Giacomazzo, Luciano Rezzolla, Nikolaos Stergioulas | Collapse of differentially rotating neutron stars and cosmic censorship | 15 pages, 15 figures. Minor changes to the text and to the
references. In press on Phys. Rev. D | Phys.Rev.D84:024022,2011 | 10.1103/PhysRevD.84.024022 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present new results on the dynamics and gravitational-wave emission from
the collapse of differentially rotating neutron stars. We have considered a
number of polytropic stellar models having different values of the
dimensionless angular momentum J/M^2, where J and M are the asymptotic angular
momentum and mass of the star, respectively. For neutron stars with J/M^2<1,
i.e., "sub-Kerr" models, we were able to find models that are dynamically
unstable and that collapse promptly to a rotating black hole. Both the dynamics
of the collapse and the consequent emission of gravitational waves resemble the
one seen for uniformly rotating stars, although with an overall decrease in the
efficiency of gravitational-wave emission. For stellar models with J/M^2>1,
i.e., "supra-Kerr" models, on the other hand, we were not able to find models
that are dynamically unstable and all of the computed supra-Kerr models were
found to be far from the stability threshold. For these models a gravitational
collapse is possible only after a very severe and artificial reduction of the
pressure, which then leads to a torus developing nonaxisymmetric instabilities
and eventually contracting to a stable axisymmetric stellar configuration.
While this does not exclude the possibility that a naked singularity can be
produced by the collapse of a differentially rotating star, it also suggests
that cosmic censorship is not violated and that generic conditions for a
supra-Kerr progenitor do not lead to a naked singularity.
| [
{
"created": "Sat, 30 Apr 2011 21:50:41 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Jul 2011 21:00:30 GMT",
"version": "v2"
}
] | 2015-03-19 | [
[
"Giacomazzo",
"Bruno",
""
],
[
"Rezzolla",
"Luciano",
""
],
[
"Stergioulas",
"Nikolaos",
""
]
] | We present new results on the dynamics and gravitational-wave emission from the collapse of differentially rotating neutron stars. We have considered a number of polytropic stellar models having different values of the dimensionless angular momentum J/M^2, where J and M are the asymptotic angular momentum and mass of the star, respectively. For neutron stars with J/M^2<1, i.e., "sub-Kerr" models, we were able to find models that are dynamically unstable and that collapse promptly to a rotating black hole. Both the dynamics of the collapse and the consequent emission of gravitational waves resemble the one seen for uniformly rotating stars, although with an overall decrease in the efficiency of gravitational-wave emission. For stellar models with J/M^2>1, i.e., "supra-Kerr" models, on the other hand, we were not able to find models that are dynamically unstable and all of the computed supra-Kerr models were found to be far from the stability threshold. For these models a gravitational collapse is possible only after a very severe and artificial reduction of the pressure, which then leads to a torus developing nonaxisymmetric instabilities and eventually contracting to a stable axisymmetric stellar configuration. While this does not exclude the possibility that a naked singularity can be produced by the collapse of a differentially rotating star, it also suggests that cosmic censorship is not violated and that generic conditions for a supra-Kerr progenitor do not lead to a naked singularity. |
2311.10559 | Yong-Hui Qi | Bum-Hoon Lee, Wonwoo Lee, and Yong-Hui Qi | Superradiance in the Kerr-Taub-NUT spacetime | 42 pages, 2 figures | null | null | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Superradiance is the effect of field waves being amplified during reflection
from a charged or rotating black hole. In this paper, we study the low-energy
dynamics of super-radiant scattering of massive scalar and massless higher spin
field perturbations in a generic axisymmetric stationary Kerr-Taub-NUT
(Newman-Unti-Tamburino) spacetime, which represents sources with both
gravitomagnetic monopole moment (magnetic mass) and gravitomagnetic dipole
moment (angular momentum). We obtain a generalized Teukolsky master equation
for all spin perturbation fields. The equations are separated into their
angular and radial parts. The angular equations lead to spin-weighted
spheroidal harmonic functions that generalize those in Kerr spacetime. We
identify an effective spin as a coupling between frequency (or energy) and the
NUT parameter. The behaviors of the radial wave function near the horizon and
at the infinite boundary are studied. We provide analytical expressions for
low-energy observables such as emission rates and cross sections of all
massless fields with spin, including scalar, neutrino, electromagnetic,
Rarita-Schwinger, and gravitational waves.
| [
{
"created": "Fri, 17 Nov 2023 14:51:36 GMT",
"version": "v1"
}
] | 2023-11-20 | [
[
"Lee",
"Bum-Hoon",
""
],
[
"Lee",
"Wonwoo",
""
],
[
"Qi",
"Yong-Hui",
""
]
] | Superradiance is the effect of field waves being amplified during reflection from a charged or rotating black hole. In this paper, we study the low-energy dynamics of super-radiant scattering of massive scalar and massless higher spin field perturbations in a generic axisymmetric stationary Kerr-Taub-NUT (Newman-Unti-Tamburino) spacetime, which represents sources with both gravitomagnetic monopole moment (magnetic mass) and gravitomagnetic dipole moment (angular momentum). We obtain a generalized Teukolsky master equation for all spin perturbation fields. The equations are separated into their angular and radial parts. The angular equations lead to spin-weighted spheroidal harmonic functions that generalize those in Kerr spacetime. We identify an effective spin as a coupling between frequency (or energy) and the NUT parameter. The behaviors of the radial wave function near the horizon and at the infinite boundary are studied. We provide analytical expressions for low-energy observables such as emission rates and cross sections of all massless fields with spin, including scalar, neutrino, electromagnetic, Rarita-Schwinger, and gravitational waves. |
1304.7020 | Cristian Stelea | Jutta Kunz, Petya G. Nedkova, Cristian Stelea | Charged black holes on Kaluza-Klein bubbles | 23 pages, 2 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct exact solutions of the Einstein-Maxwell-Dilaton field equations
in five dimensions, which describe general configurations of charged and static
black holes sitting on a Kaluza-Klein bubble. More specifically we discuss the
configurations describing two black holes sitting on a Kaluza-Klein bubble and
also the general charged static black Saturn balanced by a Kaluza-Klein bubble.
A straightforward extension of the solution generating technique leads to a new
solution describing the charged static black Saturn on the Taub-bolt instanton.
We compute the conserved charges and investigate some of the thermodynamic
properties of these systems.
| [
{
"created": "Thu, 25 Apr 2013 20:19:47 GMT",
"version": "v1"
}
] | 2013-04-29 | [
[
"Kunz",
"Jutta",
""
],
[
"Nedkova",
"Petya G.",
""
],
[
"Stelea",
"Cristian",
""
]
] | We construct exact solutions of the Einstein-Maxwell-Dilaton field equations in five dimensions, which describe general configurations of charged and static black holes sitting on a Kaluza-Klein bubble. More specifically we discuss the configurations describing two black holes sitting on a Kaluza-Klein bubble and also the general charged static black Saturn balanced by a Kaluza-Klein bubble. A straightforward extension of the solution generating technique leads to a new solution describing the charged static black Saturn on the Taub-bolt instanton. We compute the conserved charges and investigate some of the thermodynamic properties of these systems. |
0810.0746 | Yu-ichi Takamizu | Yu-ichi Takamizu and Shinji Mukohyama | Nonlinear superhorizon perturbations of non-canonical scalar field | 14 pages | JCAP 0901:013,2009 | 10.1088/1475-7516/2009/01/013 | null | gr-qc astro-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We develop a theory of non-linear cosmological perturbations at superhorizon
scales for a scalar field with a Lagrangian of the form $P(X,\phi)$, where
$X=-\partial^{\mu}\phi\partial_{\mu}\phi$ and $\phi$ is the scalar field. We
employ the ADM formalism and the spatial gradient expansion approach to obtain
general solutions valid up to the second order in the gradient expansion. This
formulation can be applied to, for example, DBI inflation models to investigate
superhorizon evolution of non-Gaussianities. With slight modification, we also
obtain general solutions valid up to the same order for a perfect fluid with a
general equation of state $P=P(\rho)$.
| [
{
"created": "Sat, 4 Oct 2008 05:29:23 GMT",
"version": "v1"
}
] | 2009-01-16 | [
[
"Takamizu",
"Yu-ichi",
""
],
[
"Mukohyama",
"Shinji",
""
]
] | We develop a theory of non-linear cosmological perturbations at superhorizon scales for a scalar field with a Lagrangian of the form $P(X,\phi)$, where $X=-\partial^{\mu}\phi\partial_{\mu}\phi$ and $\phi$ is the scalar field. We employ the ADM formalism and the spatial gradient expansion approach to obtain general solutions valid up to the second order in the gradient expansion. This formulation can be applied to, for example, DBI inflation models to investigate superhorizon evolution of non-Gaussianities. With slight modification, we also obtain general solutions valid up to the same order for a perfect fluid with a general equation of state $P=P(\rho)$. |
gr-qc/0302021 | Choquet-Bruhat | Yvonne Choquet-Bruhat and Vincent Moncrief | Non linear stability of einsteinian spacetimes with U(1) isometry group | Conference in honor of J. Leray, Tokyo 2001, Kajitani and Vaillant
ed. to appear Birkhauser | null | null | null | gr-qc | null | We prove global completeness in the expanding direction of spacetimes
satisfying the vacuum Einstein equations on a manifold of the form $\Sigma
\times S^{1}\times R$ where $\Sigma $ is a compact surface of genus $G>1.$ The
Cauchy data are supposed to be invariant with respect to the group $S^{1}$ and
sufficiently small, but we do not impose a restrictive hypothesis made in gr-qc
0112049 on the lowest eigenvalue of a relevant Laplacian. The total energy
decay still holds, but its rate depends of the asymptotic value of this
eigenvalue.
| [
{
"created": "Fri, 7 Feb 2003 20:45:13 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Choquet-Bruhat",
"Yvonne",
""
],
[
"Moncrief",
"Vincent",
""
]
] | We prove global completeness in the expanding direction of spacetimes satisfying the vacuum Einstein equations on a manifold of the form $\Sigma \times S^{1}\times R$ where $\Sigma $ is a compact surface of genus $G>1.$ The Cauchy data are supposed to be invariant with respect to the group $S^{1}$ and sufficiently small, but we do not impose a restrictive hypothesis made in gr-qc 0112049 on the lowest eigenvalue of a relevant Laplacian. The total energy decay still holds, but its rate depends of the asymptotic value of this eigenvalue. |
1601.01655 | Serguei Krasnikov | S. Krasnikov | Finite energy quantization on a topology changing spacetime | v.2 The zeroth mode is abandoned. The presentation is simplified and
clarified v.3 Title has changed. A few typos are corrected, etc | Physical Review D 94 (2016) 044055 | 10.1103/PhysRevD.94.044055 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The "trousers" spacetime is a pair of flat 2D cylinders ("legs") merging into
into a single one ("trunk"). In spite of its simplicity this spacetime has a
few features (including, in particular, a naked singularity in the "crotch")
each of which is presumably unphysical, but for none of which a mechanism is
known able to prevent its occurrence. Therefore it is interesting and important
to study the behavior of the quantum fields in such a space. Anderson and
DeWitt were the first to consider the free scalar field in the trousers
spacetime. They argued that the crotch singularity produces an infinitely
bright flash, which was interpreted as evidence that the topology of space is
dynamically preserved. Similar divergencies were later discovered by Manogue,
Copeland and Dray who used a more exotic quantization scheme. Later yet the
same result obtained within a somewhat different approach led Sorkin to the
conclusion that the topological transition in question is suppressed in quantum
gravity.
In this paper I show that the Anderson--DeWitt divergence is an artifact of
their choice of the Fock space. By choosing a different one-particle Hilbert
space one gets a quantum state in which the components of the stress-energy
tensor (SET) are bounded in the frame of a free-falling observer.
| [
{
"created": "Thu, 7 Jan 2016 20:16:41 GMT",
"version": "v1"
},
{
"created": "Tue, 24 May 2016 11:06:20 GMT",
"version": "v2"
},
{
"created": "Wed, 24 Aug 2016 13:55:39 GMT",
"version": "v3"
}
] | 2016-09-21 | [
[
"Krasnikov",
"S.",
""
]
] | The "trousers" spacetime is a pair of flat 2D cylinders ("legs") merging into into a single one ("trunk"). In spite of its simplicity this spacetime has a few features (including, in particular, a naked singularity in the "crotch") each of which is presumably unphysical, but for none of which a mechanism is known able to prevent its occurrence. Therefore it is interesting and important to study the behavior of the quantum fields in such a space. Anderson and DeWitt were the first to consider the free scalar field in the trousers spacetime. They argued that the crotch singularity produces an infinitely bright flash, which was interpreted as evidence that the topology of space is dynamically preserved. Similar divergencies were later discovered by Manogue, Copeland and Dray who used a more exotic quantization scheme. Later yet the same result obtained within a somewhat different approach led Sorkin to the conclusion that the topological transition in question is suppressed in quantum gravity. In this paper I show that the Anderson--DeWitt divergence is an artifact of their choice of the Fock space. By choosing a different one-particle Hilbert space one gets a quantum state in which the components of the stress-energy tensor (SET) are bounded in the frame of a free-falling observer. |
1608.06271 | Rod Aros Mr. | Rodrigo Aros and Danilo Diaz and Milko Estrada and Alejandra
Montecinos | Black hole at Lovelock gravity with anisotropic fluid | 16 pages, 2 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work a new family of black hole solutions in Lovelock gravity is
discussed. These solutions describe anisotropic fluids which extend to the
spatial infinity. Though far from the horizon their geometries approach some
previously known black holes solutions the location of the horizons differ.
Furthemore, although the masses of these solutions match the masses of those
previously known black holes, their temperatures and entropies differ.
| [
{
"created": "Mon, 22 Aug 2016 19:44:47 GMT",
"version": "v1"
}
] | 2016-08-23 | [
[
"Aros",
"Rodrigo",
""
],
[
"Diaz",
"Danilo",
""
],
[
"Estrada",
"Milko",
""
],
[
"Montecinos",
"Alejandra",
""
]
] | In this work a new family of black hole solutions in Lovelock gravity is discussed. These solutions describe anisotropic fluids which extend to the spatial infinity. Though far from the horizon their geometries approach some previously known black holes solutions the location of the horizons differ. Furthemore, although the masses of these solutions match the masses of those previously known black holes, their temperatures and entropies differ. |
2006.13907 | Naveena Kumara A | A. Naveena Kumara, C.L. Ahmed Rizwan, Kartheek Hegde, Md Sabir Ali and
Ajith K.M | Microstructure of five-dimensional neutral Gauss-Bonnet black hole in
anti-de Sitter spacetime via $P-V$ criticality | 14 pages, 3 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this article, we analytically investigate the microstructure of a
five-dimensional neutral Gauss-Bonnet black hole, in the background of anti-de
Sitter spacetime, using scalar curvature of the Ruppeiner geometry constructed
via adiabatic compressibility. The microstructure details associated with the
small-large black hole phase transition are probed in the parameter space of
pressure and volume. The curvature scalar shows similar properties for both
phases of the black hole, it diverges in the vicinity of critical point and
approaches zero for extremal black holes. We show that the dominant interaction
among black hole molecules is attractive. This study also affirms that the
nature of the microstructure interaction remains unchanged during the
small-large black hole phase transition, even though the microstructures are
different for both phases.
| [
{
"created": "Wed, 24 Jun 2020 17:40:04 GMT",
"version": "v1"
}
] | 2021-02-16 | [
[
"Kumara",
"A. Naveena",
""
],
[
"Rizwan",
"C. L. Ahmed",
""
],
[
"Hegde",
"Kartheek",
""
],
[
"Ali",
"Md Sabir",
""
],
[
"M",
"Ajith K.",
""
]
] | In this article, we analytically investigate the microstructure of a five-dimensional neutral Gauss-Bonnet black hole, in the background of anti-de Sitter spacetime, using scalar curvature of the Ruppeiner geometry constructed via adiabatic compressibility. The microstructure details associated with the small-large black hole phase transition are probed in the parameter space of pressure and volume. The curvature scalar shows similar properties for both phases of the black hole, it diverges in the vicinity of critical point and approaches zero for extremal black holes. We show that the dominant interaction among black hole molecules is attractive. This study also affirms that the nature of the microstructure interaction remains unchanged during the small-large black hole phase transition, even though the microstructures are different for both phases. |
1201.4994 | Kartik Prabhu | Naresh Dadhich, Josep M. Pons, Kartik Prabhu | On the static Lovelock black holes | 19 pages | GRG 45 (2013) 1131-1144 | 10.1007/s10714-013-1514-0 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider static spherically symmetric Lovelock black holes and generalize
the dimensionally continued black holes in such a way that they asymptotically
for large r go over to the d-dimensional Schwarzschild black hole in dS/AdS
spacetime. This means that the master algebraic polynomial is not degenerate
but instead its derivative is degenerate. This family of solutions contains an
interesting class of pure Lovelock black holes which are the Nth order Lovelock
{\Lambda}-vacuum solu- tions having the remarkable property that their
thermodynamical parameters have the universal character in terms of the event
horizon radius. This is in fact a characterizing property of pure Lovelock
theories. We also demonstrate the universality of the asymptotic Einstein limit
for the Lovelock black holes in general.
| [
{
"created": "Fri, 20 Jan 2012 21:06:11 GMT",
"version": "v1"
},
{
"created": "Tue, 28 May 2013 23:33:59 GMT",
"version": "v2"
}
] | 2013-05-30 | [
[
"Dadhich",
"Naresh",
""
],
[
"Pons",
"Josep M.",
""
],
[
"Prabhu",
"Kartik",
""
]
] | We consider static spherically symmetric Lovelock black holes and generalize the dimensionally continued black holes in such a way that they asymptotically for large r go over to the d-dimensional Schwarzschild black hole in dS/AdS spacetime. This means that the master algebraic polynomial is not degenerate but instead its derivative is degenerate. This family of solutions contains an interesting class of pure Lovelock black holes which are the Nth order Lovelock {\Lambda}-vacuum solu- tions having the remarkable property that their thermodynamical parameters have the universal character in terms of the event horizon radius. This is in fact a characterizing property of pure Lovelock theories. We also demonstrate the universality of the asymptotic Einstein limit for the Lovelock black holes in general. |
gr-qc/0607131 | Herbert Hamber | Herbert W. Hamber and Ruth M. Williams | Constraints on Gravitational Scaling Dimensions from Non-Local Effective
Field Equations | 14 pages | Phys.Lett.B643:228-234,2006 | 10.1016/j.physletb.2006.10.049 | CERN-PH-TH/2006-147 | gr-qc hep-th | null | Quantum corrections to the classical field equations, induced by a scale
dependent gravitational constant, are analyzed in the case of the static
isotropic metric. The requirement of general covariance for the resulting
non-local effective field equations puts severe restrictions on the nature of
the solutions that can be obtained. In general the existence of vacuum
solutions to the effective field equations restricts the value of the
gravitational scaling exponent $\nu^{-1}$ to be a positive integer greater than
one. We give further arguments suggesting that in fact only for $\nu^{-1}=3$
consistent solutions seem to exist in four dimensions.
| [
{
"created": "Fri, 28 Jul 2006 14:09:29 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Hamber",
"Herbert W.",
""
],
[
"Williams",
"Ruth M.",
""
]
] | Quantum corrections to the classical field equations, induced by a scale dependent gravitational constant, are analyzed in the case of the static isotropic metric. The requirement of general covariance for the resulting non-local effective field equations puts severe restrictions on the nature of the solutions that can be obtained. In general the existence of vacuum solutions to the effective field equations restricts the value of the gravitational scaling exponent $\nu^{-1}$ to be a positive integer greater than one. We give further arguments suggesting that in fact only for $\nu^{-1}=3$ consistent solutions seem to exist in four dimensions. |
2104.08725 | Vardarajan Suneeta | Sreejith Nair, Vardarajan Suneeta | The Black hole Black string phase transition in Einstein-Gauss-Bonnet
gravity | 23 pages, modifications, subsection added | Phys. Rev. D 104, 044042 (2021) | 10.1103/PhysRevD.104.044042 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the presence of a black hole black string phase transition in
Einstein Gauss Bonnet (EGB) gravity in the large dimension limit. The merger
point is the static spacetime connecting the black string phase with the black
hole phase. We consider several ranges of the Gauss-Bonnet parameter. We find
that there is a range when the Gauss-Bonnet corrections are subordinate to the
Einstein gravity terms in the large dimension limit, and yet the merger point
geometry does not approach a black hole away from the neck. We cannot rule out
a topology changing phase transition as argued by Kol. However as the merger
point geometry does not approach the black hole geometry asymptotically it is
not obvious that the transition is directly to a black hole phase. We also
demonstrate that for another range of the Gauss-Bonnet parameter, the merger
point geometry approaches the black hole geometry asymptotically when a certain
parameter depending on the Gauss-Bonnet parameter $\alpha$ and on the
parameters in the Einstein-Gauss-Bonnet black hole metric is small enough.
| [
{
"created": "Sun, 18 Apr 2021 05:30:29 GMT",
"version": "v1"
},
{
"created": "Wed, 30 Jun 2021 05:25:56 GMT",
"version": "v2"
}
] | 2021-08-25 | [
[
"Nair",
"Sreejith",
""
],
[
"Suneeta",
"Vardarajan",
""
]
] | We investigate the presence of a black hole black string phase transition in Einstein Gauss Bonnet (EGB) gravity in the large dimension limit. The merger point is the static spacetime connecting the black string phase with the black hole phase. We consider several ranges of the Gauss-Bonnet parameter. We find that there is a range when the Gauss-Bonnet corrections are subordinate to the Einstein gravity terms in the large dimension limit, and yet the merger point geometry does not approach a black hole away from the neck. We cannot rule out a topology changing phase transition as argued by Kol. However as the merger point geometry does not approach the black hole geometry asymptotically it is not obvious that the transition is directly to a black hole phase. We also demonstrate that for another range of the Gauss-Bonnet parameter, the merger point geometry approaches the black hole geometry asymptotically when a certain parameter depending on the Gauss-Bonnet parameter $\alpha$ and on the parameters in the Einstein-Gauss-Bonnet black hole metric is small enough. |
gr-qc/0610138 | Guihua Tian | Heng-Zhong Fang, Jian-Yang Zhu | Particle Radiation From Gibbons-Maeda Black Hole | 15 pages, no figures | null | null | null | gr-qc | null | This paper investigates the particle radiation from Gibbons-Maeda black hole.
Taking into account the self-gravitation of the particle, we calculate the
tunnelling rate of the massless particle across the horizon, then we promote
the work to the radiation of the charged particle. The calculations prove that
the rate of tunnelling equals precisely the exponent of the difference of the
black hole entropy before and after emission and the radiation spectrum
deviates from exact thermal. The conclusion supports the viewpoint of
information conservation.
| [
{
"created": "Fri, 27 Oct 2006 09:07:23 GMT",
"version": "v1"
},
{
"created": "Thu, 2 Nov 2006 06:47:03 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Fang",
"Heng-Zhong",
""
],
[
"Zhu",
"Jian-Yang",
""
]
] | This paper investigates the particle radiation from Gibbons-Maeda black hole. Taking into account the self-gravitation of the particle, we calculate the tunnelling rate of the massless particle across the horizon, then we promote the work to the radiation of the charged particle. The calculations prove that the rate of tunnelling equals precisely the exponent of the difference of the black hole entropy before and after emission and the radiation spectrum deviates from exact thermal. The conclusion supports the viewpoint of information conservation. |
1209.3731 | Olivier Sarbach | Eliana Chaverra, N\'estor Ortiz, Olivier Sarbach | Linear perturbations of self-gravitating spherically symmetric
configurations | 31 pages, no figures, to appear in PRD | Physical Review D 87, 044015 (2013) | 10.1103/PhysRevD.87.044015 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a new covariant, gauge-invariant formalism describing linear
metric perturbation fields on any spherically symmetric background in general
relativity. The advantage of this formalism relies in the fact that it does not
require a decomposition of the perturbations into spherical tensor harmonics.
Furthermore, it does not assume the background to be vacuum, nor does it
require its staticity. In the particular case of vacuum perturbations, we
derive two master equations describing the propagation of arbitrary linear
gravitational waves on a Schwarzschild black hole. When decomposed into
spherical harmonics, they reduce to covariant generalizations of the well-known
Regge-Wheeler and Zerilli equations. Next, we discuss the general case where
the metric perturbations are coupled to matter fields and derive a new
constrained wave system describing the propagation of three gauge-invariant
scalars from which the complete metric perturbations can be reconstructed. We
apply our formalism to the Einstein-Euler system, dividing the fluid
perturbations into two parts. The first part, which decouples from the metric
perturbations, obeys simple advection equations along the background flow and
describes the propagation of the entropy and the vorticity. The second part
describes a perturbed potential flow, and together with the metric
perturbations it forms a closed wave system.
| [
{
"created": "Mon, 17 Sep 2012 17:47:17 GMT",
"version": "v1"
},
{
"created": "Fri, 11 Jan 2013 00:42:41 GMT",
"version": "v2"
}
] | 2013-04-15 | [
[
"Chaverra",
"Eliana",
""
],
[
"Ortiz",
"Néstor",
""
],
[
"Sarbach",
"Olivier",
""
]
] | We present a new covariant, gauge-invariant formalism describing linear metric perturbation fields on any spherically symmetric background in general relativity. The advantage of this formalism relies in the fact that it does not require a decomposition of the perturbations into spherical tensor harmonics. Furthermore, it does not assume the background to be vacuum, nor does it require its staticity. In the particular case of vacuum perturbations, we derive two master equations describing the propagation of arbitrary linear gravitational waves on a Schwarzschild black hole. When decomposed into spherical harmonics, they reduce to covariant generalizations of the well-known Regge-Wheeler and Zerilli equations. Next, we discuss the general case where the metric perturbations are coupled to matter fields and derive a new constrained wave system describing the propagation of three gauge-invariant scalars from which the complete metric perturbations can be reconstructed. We apply our formalism to the Einstein-Euler system, dividing the fluid perturbations into two parts. The first part, which decouples from the metric perturbations, obeys simple advection equations along the background flow and describes the propagation of the entropy and the vorticity. The second part describes a perturbed potential flow, and together with the metric perturbations it forms a closed wave system. |
gr-qc/0505042 | Duncan Brown | LIGO Scientific Collaboration: B. Abbott, et al | Search for Gravitational Waves from Primordial Black Hole Binary
Coalescences in the Galactic Halo | 7 pages, 4 figures, to be submitted to Phys. Rev. D | Phys.Rev.D72:082002,2005 | 10.1103/PhysRevD.72.082002 | LIGO-P040045-04-Z | gr-qc | null | We use data from the second science run of the LIGO gravitational-wave
detectors to search for the gravitational waves from primordial black hole
(PBH) binary coalescence with component masses in the range 0.2--$1.0 M_\odot$.
The analysis requires a signal to be found in the data from both LIGO
observatories, according to a set of coincidence criteria. No inspiral signals
were found. Assuming a spherical halo with core radius 5 kpc extending to 50
kpc containing non-spinning black holes with masses in the range 0.2--$1.0
M_\odot$, we place an observational upper limit on the rate of PBH coalescence
of 63 per year per Milky Way halo (MWH) with 90% confidence.
| [
{
"created": "Tue, 10 May 2005 02:37:19 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"LIGO Scientific Collaboration",
"",
""
],
[
"Abbott",
"B.",
""
]
] | We use data from the second science run of the LIGO gravitational-wave detectors to search for the gravitational waves from primordial black hole (PBH) binary coalescence with component masses in the range 0.2--$1.0 M_\odot$. The analysis requires a signal to be found in the data from both LIGO observatories, according to a set of coincidence criteria. No inspiral signals were found. Assuming a spherical halo with core radius 5 kpc extending to 50 kpc containing non-spinning black holes with masses in the range 0.2--$1.0 M_\odot$, we place an observational upper limit on the rate of PBH coalescence of 63 per year per Milky Way halo (MWH) with 90% confidence. |
gr-qc/0312071 | Hongwei Yu | Hongwei Yu and Puxun Wu | Quantum inequalities for the free Rarita-Schwinger fields in flat
spacetime | Revtex, 11 pages, to appear in PRD | Phys.Rev. D69 (2004) 064008 | 10.1103/PhysRevD.69.064008 | null | gr-qc hep-th | null | Using the methods developed by Fewster and colleagues, we derive a quantum
inequality for the free massive spin-${3\over 2}$ Rarita-Schwinger fields in
the four dimensional Minkowski spacetime. Our quantum inequality bound for the
Rarita-Schwinger fields is weaker, by a factor of 2, than that for the
spin-${1\over 2}$ Dirac fields. This fact along with other quantum inequalities
obtained by various other authors for the fields of integer spin (bosonic
fields) using similar methods lead us to conjecture that, in the flat
spacetime, separately for bosonic and fermionic fields, the quantum inequality
bound gets weaker as the the number of degrees of freedom of the field
increases. A plausible physical reason might be that the more the number of
field degrees of freedom, the more freedom one has to create negative energy,
therefore, the weaker the quantum inequality bound.
| [
{
"created": "Tue, 16 Dec 2003 02:36:30 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Yu",
"Hongwei",
""
],
[
"Wu",
"Puxun",
""
]
] | Using the methods developed by Fewster and colleagues, we derive a quantum inequality for the free massive spin-${3\over 2}$ Rarita-Schwinger fields in the four dimensional Minkowski spacetime. Our quantum inequality bound for the Rarita-Schwinger fields is weaker, by a factor of 2, than that for the spin-${1\over 2}$ Dirac fields. This fact along with other quantum inequalities obtained by various other authors for the fields of integer spin (bosonic fields) using similar methods lead us to conjecture that, in the flat spacetime, separately for bosonic and fermionic fields, the quantum inequality bound gets weaker as the the number of degrees of freedom of the field increases. A plausible physical reason might be that the more the number of field degrees of freedom, the more freedom one has to create negative energy, therefore, the weaker the quantum inequality bound. |
1302.2151 | Dawood Kothawala Dr. | T. Padmanabhan, Dawood Kothawala | Lanczos-Lovelock models of gravity | 95 pages; final version published in Physics Reports | Physics Reports 531: 115-171 (2013) | 10.1016/j.physrep.2013.05.007 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Lanczos-Lovelock models of gravity represent a natural and elegant
generalization of Einstein's theory of gravity to higher dimensions. They are
characterized by the fact that the field equations only contain up to second
derivatives of the metric even though the action functional can be a quadratic
or higher degree polynomial in the curvature tensor. Because these models share
several key properties of Einstein's theory they serve as a useful set of
candidate models for testing the emergent paradigm for gravity. This review
highlights several geometrical and thermodynamical aspects of Lanczos-Lovelock
models which have attracted recent attention.
| [
{
"created": "Fri, 8 Feb 2013 21:00:06 GMT",
"version": "v1"
},
{
"created": "Tue, 12 Feb 2013 13:18:33 GMT",
"version": "v2"
},
{
"created": "Mon, 27 May 2013 06:28:25 GMT",
"version": "v3"
},
{
"created": "Thu, 12 Dec 2013 13:31:52 GMT",
"version": "v4"
}
] | 2013-12-13 | [
[
"Padmanabhan",
"T.",
""
],
[
"Kothawala",
"Dawood",
""
]
] | Lanczos-Lovelock models of gravity represent a natural and elegant generalization of Einstein's theory of gravity to higher dimensions. They are characterized by the fact that the field equations only contain up to second derivatives of the metric even though the action functional can be a quadratic or higher degree polynomial in the curvature tensor. Because these models share several key properties of Einstein's theory they serve as a useful set of candidate models for testing the emergent paradigm for gravity. This review highlights several geometrical and thermodynamical aspects of Lanczos-Lovelock models which have attracted recent attention. |
gr-qc/0301024 | Kenneth Nordtvedt | Kenneth Nordtvedt | Lunar Laser Ranging - a comprehensive probe of post-Newtonian gravity | 19 pages, 3 figures, PCTex32 v3.4, for proceedings of Villa
Mondragone International School of Gravitation and Cosmology, September 2002 | null | null | null | gr-qc | null | More than 30 years of lunar laser ranging has produced several key tests of
gravitational theory, including confirmation that bodies fall in external
gravity at rates independent of their internal gravitational binding energy,
and that Newton's G is constant to a part in 10^12 per year precision. The
fitting of LLR data depends on the entire scope of 1/c^2 order features of the
gravitational equation of motion, including non-linearity, gravitomagnetism,
and inductive inertial forces.
| [
{
"created": "Tue, 7 Jan 2003 18:47:47 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Nordtvedt",
"Kenneth",
""
]
] | More than 30 years of lunar laser ranging has produced several key tests of gravitational theory, including confirmation that bodies fall in external gravity at rates independent of their internal gravitational binding energy, and that Newton's G is constant to a part in 10^12 per year precision. The fitting of LLR data depends on the entire scope of 1/c^2 order features of the gravitational equation of motion, including non-linearity, gravitomagnetism, and inductive inertial forces. |
gr-qc/0112045 | Ivangoe Pestov | I.B. Pestov | On Principle of Universality of Gravitational Interactions | LATeX, 12 pages, no figures and tables | null | null | JINR P2-97-156 | gr-qc | null | In this work, the experiment is discussed on the verification of the
principle of universality of gravitational interactions and some related
problems of gravity theory and physics of elementary particles. The meaning of
this proposal lies in the fact that the self-consistency of General Relativity,
as it turns out, presuppose the existence of the nongravitating form of energy.
Theory predicts that electrons are particles that transfer the nongravitating
form of energy.
| [
{
"created": "Wed, 19 Dec 2001 16:17:41 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Pestov",
"I. B.",
""
]
] | In this work, the experiment is discussed on the verification of the principle of universality of gravitational interactions and some related problems of gravity theory and physics of elementary particles. The meaning of this proposal lies in the fact that the self-consistency of General Relativity, as it turns out, presuppose the existence of the nongravitating form of energy. Theory predicts that electrons are particles that transfer the nongravitating form of energy. |
2302.05088 | Ritam Mallick | KamalKrishna Nath, Ritam Mallick, Sagnik Chatterjee | Universal Relations For Generic Family Of Neutron Star Equations Of
State | 8 pages, 14 figures | Monthly Notices of the Royal Astronomical Society, Volume 524,
Issue 1, September 2023, Pages 1438 1447 | 10.1093/mnras/stad1967 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Universal relations are important in testing many theories of physics. In the
case of general relativity, we have the celebrated no-hair theorem for black
holes. Unfortunately, the other compact stars, like neutron stars and white
dwarfs, do not have such universal relation. However, neutron stars (and quark
stars) have recently been found to follow certain universality, the I-Love-Q
relations. These relations can provide a greater understanding of the
structural and macro properties of compact astrophysical objects with knowledge
of any one of the observables. The reason behind this is the lack of
sensitivity to the relations with the equation of state of matter. In our
present work, we have investigated the consistency of universal relations for a
generic family of equations of state, which follows all the recent
astrophysical constraints. Although the spread in the EoS is significant the
universal nature of the trio holds relatively well up to a certain tolerance
limit. The deviation from universality is seen to cross the tolerance limit
with EoS, which is characteristically different from the original set.
| [
{
"created": "Fri, 10 Feb 2023 07:13:38 GMT",
"version": "v1"
}
] | 2023-10-25 | [
[
"Nath",
"KamalKrishna",
""
],
[
"Mallick",
"Ritam",
""
],
[
"Chatterjee",
"Sagnik",
""
]
] | Universal relations are important in testing many theories of physics. In the case of general relativity, we have the celebrated no-hair theorem for black holes. Unfortunately, the other compact stars, like neutron stars and white dwarfs, do not have such universal relation. However, neutron stars (and quark stars) have recently been found to follow certain universality, the I-Love-Q relations. These relations can provide a greater understanding of the structural and macro properties of compact astrophysical objects with knowledge of any one of the observables. The reason behind this is the lack of sensitivity to the relations with the equation of state of matter. In our present work, we have investigated the consistency of universal relations for a generic family of equations of state, which follows all the recent astrophysical constraints. Although the spread in the EoS is significant the universal nature of the trio holds relatively well up to a certain tolerance limit. The deviation from universality is seen to cross the tolerance limit with EoS, which is characteristically different from the original set. |
2003.08416 | Gabriel Herczeg | Stephon Alexander, Gabriel Herczeg, Jinglong Liu, Evan McDonough | Chiral Symmetry and the Cosmological Constant | 10 pages, some typographical errors corrected, results unchanged | Phys. Rev. D 102, 083526 (2020) | 10.1103/PhysRevD.102.083526 | Vol. 102, Iss. 8 -- 15 October 2020 | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we provide a link between a nearly vanishing cosmological
constant and chiral symmetry. This is accomplished with a modification of
General Relativity coupled to a topological field theory, namely BF theory by
introducing fermions charged under the BF theory gauge group. We find that the
cosmological constant sources a chiral anomaly for the fermions, providing a
`technical naturalness' explanation for the smallness of the observed
cosmological constant. Applied to the early universe, we show that production
of fermions during inflation can provide all the dark matter in the universe
today, in the form of superheavy dark baryons.
| [
{
"created": "Wed, 18 Mar 2020 18:07:09 GMT",
"version": "v1"
},
{
"created": "Thu, 9 Apr 2020 18:45:42 GMT",
"version": "v2"
},
{
"created": "Mon, 3 May 2021 20:09:25 GMT",
"version": "v3"
}
] | 2021-05-05 | [
[
"Alexander",
"Stephon",
""
],
[
"Herczeg",
"Gabriel",
""
],
[
"Liu",
"Jinglong",
""
],
[
"McDonough",
"Evan",
""
]
] | In this work we provide a link between a nearly vanishing cosmological constant and chiral symmetry. This is accomplished with a modification of General Relativity coupled to a topological field theory, namely BF theory by introducing fermions charged under the BF theory gauge group. We find that the cosmological constant sources a chiral anomaly for the fermions, providing a `technical naturalness' explanation for the smallness of the observed cosmological constant. Applied to the early universe, we show that production of fermions during inflation can provide all the dark matter in the universe today, in the form of superheavy dark baryons. |
gr-qc/9502042 | James H. Horne | Kevin C.K. Chan, James H. Horne, and Robert B. Mann | Charged Dilaton Black Holes with Unusual Asymptotics | 24 pages, harvmac.tex, no figures | Nucl.Phys.B447:441-464,1995 | 10.1016/0550-3213(95)00205-7 | null | gr-qc | null | We present a new class of black hole solutions in Einstein-Maxwell-dilaton
gravity in $n \ge 4$ dimensions. These solutions have regular horizons and a
singularity only at the origin. Their asymptotic behavior is neither
asymptotically flat nor (anti-) de Sitter. Similar solutions exist for certain
Liouville-type potentials for the dilaton.
| [
{
"created": "Mon, 27 Feb 1995 15:24:09 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Chan",
"Kevin C. K.",
""
],
[
"Horne",
"James H.",
""
],
[
"Mann",
"Robert B.",
""
]
] | We present a new class of black hole solutions in Einstein-Maxwell-dilaton gravity in $n \ge 4$ dimensions. These solutions have regular horizons and a singularity only at the origin. Their asymptotic behavior is neither asymptotically flat nor (anti-) de Sitter. Similar solutions exist for certain Liouville-type potentials for the dilaton. |
0904.1867 | Wade Naylor | H.T. Cho (Tamkang U.), A.S. Cornell (U. Witwatersrand), Jason Doukas
(Melbourne U.), Wade Naylor (Ritsumeikan U.) | Asymptotic iteration method for spheroidal harmonics of
higher-dimensional Kerr-(A)dS black holes | 7 pages, 6 tables, LaTeX; typos corrected and reference added; table
clarity improved, 2 figures and more references added (now 9 pages) | Phys.Rev.D80:064022,2009 | 10.1103/PhysRevD.80.064022 | null | gr-qc hep-th math.NA | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we calculate the angular eigenvalues of the $(n+4)$-dimensional
{\it simply} rotating Kerr-(A)dS spheroidal harmonics using the Asymptotic
Iteration Method (AIM). We make some comparisons between this method and that
of the Continued Fraction Method (CFM) and use the latter to check our results.
We also present analytic expressions for the small rotation limit up to
$O(c^3)$ with the coefficient of each power up to $O(\alpha^2)$, where
$c=a\omega$ and $\alpha=a^2 \Lambda$ ($a$ is the angular velocity, $\omega$ the
frequency and $\Lambda$ the cosmological constant).
| [
{
"created": "Sun, 12 Apr 2009 15:04:19 GMT",
"version": "v1"
},
{
"created": "Sat, 18 Apr 2009 14:48:22 GMT",
"version": "v2"
},
{
"created": "Thu, 30 Apr 2009 08:45:11 GMT",
"version": "v3"
},
{
"created": "Mon, 31 Aug 2009 14:30:53 GMT",
"version": "v4"
}
] | 2011-04-11 | [
[
"Cho",
"H. T.",
"",
"Tamkang U."
],
[
"Cornell",
"A. S.",
"",
"U. Witwatersrand"
],
[
"Doukas",
"Jason",
"",
"Melbourne U."
],
[
"Naylor",
"Wade",
"",
"Ritsumeikan U."
]
] | In this work we calculate the angular eigenvalues of the $(n+4)$-dimensional {\it simply} rotating Kerr-(A)dS spheroidal harmonics using the Asymptotic Iteration Method (AIM). We make some comparisons between this method and that of the Continued Fraction Method (CFM) and use the latter to check our results. We also present analytic expressions for the small rotation limit up to $O(c^3)$ with the coefficient of each power up to $O(\alpha^2)$, where $c=a\omega$ and $\alpha=a^2 \Lambda$ ($a$ is the angular velocity, $\omega$ the frequency and $\Lambda$ the cosmological constant). |
1709.06712 | Masaru Siino | Masaru Siino | Dynamical deformation of 2+1 dimensional double torus universe | 19pages, 9 figures | null | null | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In (2+1)-dimensional pure gravity with cosmological constant, the dynamics of
double torus universe with pinching parameter is investigated. Each mode of
affine stretching deformation is illustrated in the context of horizontal
foliation along the holomorphic quadratic differential. The formulation of the
Einstein Hilbert action for the parameters of the affine stretching is
developed. Then the dynamics along one holomorphic quadratic differential will
be solved concretely.
| [
{
"created": "Wed, 20 Sep 2017 03:36:20 GMT",
"version": "v1"
}
] | 2017-09-21 | [
[
"Siino",
"Masaru",
""
]
] | In (2+1)-dimensional pure gravity with cosmological constant, the dynamics of double torus universe with pinching parameter is investigated. Each mode of affine stretching deformation is illustrated in the context of horizontal foliation along the holomorphic quadratic differential. The formulation of the Einstein Hilbert action for the parameters of the affine stretching is developed. Then the dynamics along one holomorphic quadratic differential will be solved concretely. |
1509.04983 | Joao Paulo Manoel Pitelli | J. P. M. Pitelli | Cosmology in $(1+1)$-dimensional Ho\v{r}ava-Lifshitz theory of gravity | 5 pages. To appear in Phys Rev D | Phys. Rev. D, 92, 084012 (2015) | 10.1103/PhysRevD.92.084012 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The $(1+1)$-dimensional Friedmann-Robertson-Walker (FRW) universe filled with
a perfect fluid with equation of state $p=\omega \rho$ is analyzed through the
view of Ho\v rava-Lifshitz (HL) theory of gravity. In this theory, the
anisotropic scaling of space and time breaks Lorentz invariance of General
Relativity (GR) in such a way that the gravitational action is no longer a
topological invariant and the theory becomes dynamical. With the introduction
of a perfect fluid through Schutz formalism, it is shown that the resulting
dynamical theory is very similar to the two-dimensional Jackiw-Teitelboim (JT)
model, where a dilatonic degree of freedom is introduced to force a dynamical
theory. However, in HL theory, the introduction of a dilaton field is not
necessary.
| [
{
"created": "Wed, 16 Sep 2015 17:50:19 GMT",
"version": "v1"
}
] | 2016-05-09 | [
[
"Pitelli",
"J. P. M.",
""
]
] | The $(1+1)$-dimensional Friedmann-Robertson-Walker (FRW) universe filled with a perfect fluid with equation of state $p=\omega \rho$ is analyzed through the view of Ho\v rava-Lifshitz (HL) theory of gravity. In this theory, the anisotropic scaling of space and time breaks Lorentz invariance of General Relativity (GR) in such a way that the gravitational action is no longer a topological invariant and the theory becomes dynamical. With the introduction of a perfect fluid through Schutz formalism, it is shown that the resulting dynamical theory is very similar to the two-dimensional Jackiw-Teitelboim (JT) model, where a dilatonic degree of freedom is introduced to force a dynamical theory. However, in HL theory, the introduction of a dilaton field is not necessary. |
0712.3787 | Mark Hannam | Mark Hannam, Sascha Husa, Bernd Br\"ugmann, Achamveedu Gopakumar | Comparison between numerical-relativity and post-Newtonian waveforms
from spinning binaries: the orbital hang-up case | 10 pages, 6 figures. Matches version published in PRD | Phys.Rev.D78:104007,2008 | 10.1103/PhysRevD.78.104007 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compare results from numerical simulations of spinning binaries in the
"orbital hangup" case, where the binary completes at least nine orbits before
merger, with post-Newtonian results using the approximants TaylorT1, T4 and Et.
We find that, over the ten cycles before the gravitational-wave frequency
reaches $M\omega = 0.1$, the accumulated phase disagreement between NR and
2.5PN results is less than three radians, and is less than 2.5 radians when
using 3.5PN results. The amplitude disagreement between NR and restricted PN
results increases with the black holes' spin, from about 6% in the equal-mass
case to 12% when the black holes' spins are $S_i/M_i^2 = 0.85$. Finally, our
results suggest that the merger waveform will play an important role in
estimating the spin from such inspiral waveforms.
| [
{
"created": "Fri, 21 Dec 2007 20:03:04 GMT",
"version": "v1"
},
{
"created": "Sun, 23 Dec 2007 19:25:32 GMT",
"version": "v2"
},
{
"created": "Wed, 26 Nov 2008 09:59:23 GMT",
"version": "v3"
}
] | 2008-11-26 | [
[
"Hannam",
"Mark",
""
],
[
"Husa",
"Sascha",
""
],
[
"Brügmann",
"Bernd",
""
],
[
"Gopakumar",
"Achamveedu",
""
]
] | We compare results from numerical simulations of spinning binaries in the "orbital hangup" case, where the binary completes at least nine orbits before merger, with post-Newtonian results using the approximants TaylorT1, T4 and Et. We find that, over the ten cycles before the gravitational-wave frequency reaches $M\omega = 0.1$, the accumulated phase disagreement between NR and 2.5PN results is less than three radians, and is less than 2.5 radians when using 3.5PN results. The amplitude disagreement between NR and restricted PN results increases with the black holes' spin, from about 6% in the equal-mass case to 12% when the black holes' spins are $S_i/M_i^2 = 0.85$. Finally, our results suggest that the merger waveform will play an important role in estimating the spin from such inspiral waveforms. |
2405.12188 | Matthew Maitra | Matthew Maitra, Jeroen Tromp | Cosserat elasticity as the weak-field limit of Einstein--Cartan
relativity | null | null | 10.1103/PhysRevD.109.104052 | null | gr-qc physics.geo-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The weak-field limit of Einstein--Cartan (EC) relativity is studied. The
equations of EC theory are rewritten such that they formally resemble those of
Einstein General Relativity (EGR); this allows ideas from post-Newtonian theory
to be imported without essential change. The equations of motion are then
written both at first post-Newtonian (1PN) order and at 1.5PN order. EC
theory's 1PN equations of motion are found to be those of a micropolar/Cosserat
elastic medium, along with a decoupled evolution equation for non-classical,
spin-related fields. It seems that a necessary condition for these results to
hold is that one chooses the non-classical fields to scale with the speed of
light in a certain empirically reasonable way. Finally, the 1.5PN equations
give greater insight into the coupling between energy-momentum and spin within
slowly moving, weakly gravitating matter. Specifically, the weakly relativistic
modifications to Cosserat theory involve a gravitational torque and an
augmentation of the gravitational force due to a `dynamic mass moment density'
with an accompanying `dynamic mass moment density flux', and new forms of
linear momentum density captured by a `dynamic mass density flux' and a
`dynamic momentum density'.
| [
{
"created": "Mon, 20 May 2024 17:20:56 GMT",
"version": "v1"
}
] | 2024-05-21 | [
[
"Maitra",
"Matthew",
""
],
[
"Tromp",
"Jeroen",
""
]
] | The weak-field limit of Einstein--Cartan (EC) relativity is studied. The equations of EC theory are rewritten such that they formally resemble those of Einstein General Relativity (EGR); this allows ideas from post-Newtonian theory to be imported without essential change. The equations of motion are then written both at first post-Newtonian (1PN) order and at 1.5PN order. EC theory's 1PN equations of motion are found to be those of a micropolar/Cosserat elastic medium, along with a decoupled evolution equation for non-classical, spin-related fields. It seems that a necessary condition for these results to hold is that one chooses the non-classical fields to scale with the speed of light in a certain empirically reasonable way. Finally, the 1.5PN equations give greater insight into the coupling between energy-momentum and spin within slowly moving, weakly gravitating matter. Specifically, the weakly relativistic modifications to Cosserat theory involve a gravitational torque and an augmentation of the gravitational force due to a `dynamic mass moment density' with an accompanying `dynamic mass moment density flux', and new forms of linear momentum density captured by a `dynamic mass density flux' and a `dynamic momentum density'. |
gr-qc/0701001 | Hyun Kyu Lee | V. Frolov (1), K. Kim (2), H.K. Lee (1 and 2) ((1) University of
Alberta, (2) Hanyang University) | Spectral Broadening of Radiation from Relativistic Collapsing Objects | 4 pages, 4 figures, Typos are corrected and substantial parts of main
text are rephrased for more better presentation. 1 reference is added | Phys.Rev.D75:087501,2007 | 10.1103/PhysRevD.75.087501 | Alberta-Thy-02-07 | gr-qc astro-ph | null | We study light curves and the spectral broadening of the radiation emitted
during the finite interval of time by a surface of a collapsing object. We
study a simplified model of monochromatic radiations from a spherical surface
which is assumed to be falling freely. We discuss the possible way how to infer
the physical parameters, such as the mass and radii of emission, from the light
curves and spectral broadenings.
| [
{
"created": "Sat, 30 Dec 2006 00:04:08 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Feb 2007 01:46:41 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Frolov",
"V.",
"",
"1 and 2"
],
[
"Kim",
"K.",
"",
"1 and 2"
],
[
"Lee",
"H. K.",
"",
"1 and 2"
]
] | We study light curves and the spectral broadening of the radiation emitted during the finite interval of time by a surface of a collapsing object. We study a simplified model of monochromatic radiations from a spherical surface which is assumed to be falling freely. We discuss the possible way how to infer the physical parameters, such as the mass and radii of emission, from the light curves and spectral broadenings. |
1307.1481 | \.Ibrahim Semiz | Koray D\"uzta\c{s} and \.Ibrahim Semiz | Cosmic Censorship, Black Holes and Integer-spin Test Fields | 4 pages, no figures. In this version, Sections II and III are
rewritten for a better derivation of the conclusion, which remains unchanged.
Now approximately matches published version [has more detail in references] | Phys. Rev. D 88, 064043 (2013) | 10.1103/PhysRevD.88.064043 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It has been argued that, starting with a slightly sub-extremal Kerr black
hole instead of an extremal one, it is possible to overspin a black hole past
the extremal limit and turn it into a naked singularity by sending test bodies,
if one neglects radiative and self-force effects. In this work we show that (i)
an extremal Kerr black hole can not be overspun as a result of the interaction
with massless integer spin test fields (scalar, electromagnetic, or
gravitational), (ii) overspinning can be achieved if we start with a nearly
extremal black hole instead, and (iii) for the scalar field, the argument
applies to more general black holes, and also allows use of a more general
field configuration. Our analysis also neglects radiative and self-force
effects.
| [
{
"created": "Thu, 4 Jul 2013 20:15:53 GMT",
"version": "v1"
},
{
"created": "Sat, 12 Oct 2013 15:17:05 GMT",
"version": "v2"
}
] | 2015-06-16 | [
[
"Düztaş",
"Koray",
""
],
[
"Semiz",
"İbrahim",
""
]
] | It has been argued that, starting with a slightly sub-extremal Kerr black hole instead of an extremal one, it is possible to overspin a black hole past the extremal limit and turn it into a naked singularity by sending test bodies, if one neglects radiative and self-force effects. In this work we show that (i) an extremal Kerr black hole can not be overspun as a result of the interaction with massless integer spin test fields (scalar, electromagnetic, or gravitational), (ii) overspinning can be achieved if we start with a nearly extremal black hole instead, and (iii) for the scalar field, the argument applies to more general black holes, and also allows use of a more general field configuration. Our analysis also neglects radiative and self-force effects. |
gr-qc/0003083 | Alberto Saa | Alberto Saa | Chaos around the superposition of a monopole and a thick disk | 11 pages, 4 figures | Phys.Lett. A269 (2000) 204-208 | 10.1016/S0375-9601(00)00256-5 | null | gr-qc | null | We extend recent investigations on the integrability of oblique orbits of
test particles under the gravitational field corresponding to the superposition
of an infinitesimally thin disk and a monopole to the more realistic case, for
astrophysical purposes, of a thick disk. Exhaustive numerical analyses were
performed and the robustness of the recent results is confirmed. We also found
that, for smooth distributions of matter, the disk thickness can attenuate the
chaotic behavior of the bounded oblique orbits. Perturbations leading to the
breakdown of the reflection symmetry about the equatorial plane, nevertheless,
may enhance significantly the chaotic behavior, in agreement with recent
studies on oblate models.
| [
{
"created": "Tue, 21 Mar 2000 17:38:24 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Saa",
"Alberto",
""
]
] | We extend recent investigations on the integrability of oblique orbits of test particles under the gravitational field corresponding to the superposition of an infinitesimally thin disk and a monopole to the more realistic case, for astrophysical purposes, of a thick disk. Exhaustive numerical analyses were performed and the robustness of the recent results is confirmed. We also found that, for smooth distributions of matter, the disk thickness can attenuate the chaotic behavior of the bounded oblique orbits. Perturbations leading to the breakdown of the reflection symmetry about the equatorial plane, nevertheless, may enhance significantly the chaotic behavior, in agreement with recent studies on oblate models. |
0906.5108 | Plamen Fiziev | Plamen P. Fiziev | Teukolsky-Starobinsky Identities - a Novel Derivation and
Generalizations | 8 pages, LaTeX file, no figures, final version | PHYSICAL REVIEW D 80, 124001 (2009) | 10.1103/PhysRevD.80.124001 | SU-TH-01-06-2009 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a novel derivation of the Teukolsky-Starobinsky identities, based
on properties of the confluent Heun functions. These functions define
analytically all exact solutions to the Teukolsky master equation, as well as
to the Regge-Wheeler and Zerilli ones. The class of solutions, subject to
Teukolsky-Starobinsky type of identities is studied. Our generalization of the
Teukolsky-Starobinsky identities is valid for the already studied linear
perturbations to the Kerr and Schwarzschild metrics, as well as for large new
classes of of such perturbations which are explicitly described in the present
article. Symmetry of parameters of confluent Heun's functions is shown to stay
behind the behavior of the known solutions under the change of the sign of
their spin weights. A new efficient recurrent method for calculation of
Starobinsky's constant is described.
| [
{
"created": "Sun, 28 Jun 2009 05:31:48 GMT",
"version": "v1"
},
{
"created": "Wed, 26 Aug 2009 15:46:45 GMT",
"version": "v2"
},
{
"created": "Mon, 12 Oct 2009 05:50:38 GMT",
"version": "v3"
},
{
"created": "Wed, 2 Dec 2009 17:12:48 GMT",
"version": "v4"
}
] | 2013-05-29 | [
[
"Fiziev",
"Plamen P.",
""
]
] | We present a novel derivation of the Teukolsky-Starobinsky identities, based on properties of the confluent Heun functions. These functions define analytically all exact solutions to the Teukolsky master equation, as well as to the Regge-Wheeler and Zerilli ones. The class of solutions, subject to Teukolsky-Starobinsky type of identities is studied. Our generalization of the Teukolsky-Starobinsky identities is valid for the already studied linear perturbations to the Kerr and Schwarzschild metrics, as well as for large new classes of of such perturbations which are explicitly described in the present article. Symmetry of parameters of confluent Heun's functions is shown to stay behind the behavior of the known solutions under the change of the sign of their spin weights. A new efficient recurrent method for calculation of Starobinsky's constant is described. |
gr-qc/0012054 | Denis Puy | N. Straumann (Institute of Theoretical Physics, University of Zurich,
Switzerland) | On Pauli's invention of non-abelian Kaluza-Klein Theory in 1953 | 4 pages, Ninth Marcel Grossmann Proceedings | null | null | null | gr-qc hep-th | null | There are documents which show that Wolfgang Pauli developed in 1953 the
first consistent generalization of the five-dimensional theory of Kaluza,
Klein, Fock and others to a higher dimensional internal space. Because he saw
no way to give masses to the gauge bosons, he refrained from publishing his
results formally.
| [
{
"created": "Fri, 15 Dec 2000 14:49:56 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Straumann",
"N.",
"",
"Institute of Theoretical Physics, University of Zurich,\n Switzerland"
]
] | There are documents which show that Wolfgang Pauli developed in 1953 the first consistent generalization of the five-dimensional theory of Kaluza, Klein, Fock and others to a higher dimensional internal space. Because he saw no way to give masses to the gauge bosons, he refrained from publishing his results formally. |
gr-qc/0502003 | Jose Natario | Joao Costa and Jose Natario | Homogeneous cosmologies from the quasi-Maxwell formalism | 15 pages, references added | J.Math.Phys. 46 (2005) 082501 | 10.1063/1.2009587 | null | gr-qc | null | We show how to use the quasi-Maxwell formalism to obtain solutions of
Einstein's field equations corresponding to homogeneous cosmologies - namely
Einstein's universe, Godel's universe and the Ozsvath-Farnsworth-Kerr class I
solutions - written in frames for which the associated observers are
stationary.
| [
{
"created": "Tue, 1 Feb 2005 16:22:36 GMT",
"version": "v1"
},
{
"created": "Wed, 2 Feb 2005 10:44:52 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Costa",
"Joao",
""
],
[
"Natario",
"Jose",
""
]
] | We show how to use the quasi-Maxwell formalism to obtain solutions of Einstein's field equations corresponding to homogeneous cosmologies - namely Einstein's universe, Godel's universe and the Ozsvath-Farnsworth-Kerr class I solutions - written in frames for which the associated observers are stationary. |
1504.05889 | Chris Messenger | C. Messenger, H. J. Bulten, S. G. Crowder, V. Dergachev, D. K.
Galloway, E. Goetz, R. J. G. Jonker, P. D. Lasky, G. D. Meadors, A. Melatos,
S. Premachandra, K. Riles, L. Sammut, E. H. Thrane, J. T. Whelan, and Y.
Zhang | Gravitational waves from Sco X-1: A comparison of search methods and
prospects for detection with advanced detectors | 33 pages, 11 figures | Phys. Rev. D 92, 023006 (2015) | 10.1103/PhysRevD.92.023006 | LIGO-P1400217-v3 | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The low-mass X-ray binary Scorpius X-1 (Sco X-1) is potentially the most
luminous source of continuous gravitational-wave radiation for interferometers
such as LIGO and Virgo. For low-mass X-ray binaries this radiation would be
sustained by active accretion of matter from its binary companion. With the
Advanced Detector Era fast approaching, work is underway to develop an array of
robust tools for maximizing the science and detection potential of Sco X-1. We
describe the plans and progress of a project designed to compare the numerous
independent search algorithms currently available. We employ a mock-data
challenge in which the search pipelines are tested for their relative
proficiencies in parameter estimation, computational efficiency, robust- ness,
and most importantly, search sensitivity. The mock-data challenge data contains
an ensemble of 50 Scorpius X-1 (Sco X-1) type signals, simulated within a
frequency band of 50-1500 Hz. Simulated detector noise was generated assuming
the expected best strain sensitivity of Advanced LIGO and Advanced VIRGO ($4
\times 10^{-24}$ Hz$^{-1/2}$). A distribution of signal amplitudes was then
chosen so as to allow a useful comparison of search methodologies. A factor of
2 in strain separates the quietest detected signal, at $6.8 \times 10^{-26}$
strain, from the torque-balance limit at a spin frequency of 300 Hz, although
this limit could range from $1.2 \times 10^{-25}$ (25 Hz) to $2.2 \times
10^{-26}$ (750 Hz) depending on the unknown frequency of Sco X-1. With future
improvements to the search algorithms and using advanced detector data, our
expectations for probing below the theoretical torque-balance strain limit are
optimistic.
| [
{
"created": "Wed, 22 Apr 2015 17:08:07 GMT",
"version": "v1"
}
] | 2015-07-15 | [
[
"Messenger",
"C.",
""
],
[
"Bulten",
"H. J.",
""
],
[
"Crowder",
"S. G.",
""
],
[
"Dergachev",
"V.",
""
],
[
"Galloway",
"D. K.",
""
],
[
"Goetz",
"E.",
""
],
[
"Jonker",
"R. J. G.",
""
],
[
"Lasky"... | The low-mass X-ray binary Scorpius X-1 (Sco X-1) is potentially the most luminous source of continuous gravitational-wave radiation for interferometers such as LIGO and Virgo. For low-mass X-ray binaries this radiation would be sustained by active accretion of matter from its binary companion. With the Advanced Detector Era fast approaching, work is underway to develop an array of robust tools for maximizing the science and detection potential of Sco X-1. We describe the plans and progress of a project designed to compare the numerous independent search algorithms currently available. We employ a mock-data challenge in which the search pipelines are tested for their relative proficiencies in parameter estimation, computational efficiency, robust- ness, and most importantly, search sensitivity. The mock-data challenge data contains an ensemble of 50 Scorpius X-1 (Sco X-1) type signals, simulated within a frequency band of 50-1500 Hz. Simulated detector noise was generated assuming the expected best strain sensitivity of Advanced LIGO and Advanced VIRGO ($4 \times 10^{-24}$ Hz$^{-1/2}$). A distribution of signal amplitudes was then chosen so as to allow a useful comparison of search methodologies. A factor of 2 in strain separates the quietest detected signal, at $6.8 \times 10^{-26}$ strain, from the torque-balance limit at a spin frequency of 300 Hz, although this limit could range from $1.2 \times 10^{-25}$ (25 Hz) to $2.2 \times 10^{-26}$ (750 Hz) depending on the unknown frequency of Sco X-1. With future improvements to the search algorithms and using advanced detector data, our expectations for probing below the theoretical torque-balance strain limit are optimistic. |
1005.3404 | Kiyoshi Shiraishi | Nahomi Kan (Yamaguchi Junior College) and Kiyoshi Shiraishi (Yamaguchi
University) | Interparticle Potential up to Next-to-leading Order for Gravitational,
Electrical, and Dilatonic Forces | 19 pages, 19 figures, RevTeX4.1. Revised version, Title changed | General Relativity and Gravitation, Volume 44, Number 4, (2012)
887-903 | 10.1007/s10714-011-1314-3 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Long-range forces up to next-to-leading order are computed in the framework
of the Einstein-Maxwell-dilaton system by means of a semiclassical approach to
gravity. As has been recently shown, this approach is effective if one of the
masses under consideration is significantly greater than all the energies
involved in the system. Further, we obtain the condition for the equilibrium of
charged masses in the system.
| [
{
"created": "Wed, 19 May 2010 10:28:57 GMT",
"version": "v1"
},
{
"created": "Tue, 8 Jun 2010 01:27:35 GMT",
"version": "v2"
},
{
"created": "Mon, 5 Dec 2011 05:18:05 GMT",
"version": "v3"
}
] | 2012-03-30 | [
[
"Kan",
"Nahomi",
"",
"Yamaguchi Junior College"
],
[
"Shiraishi",
"Kiyoshi",
"",
"Yamaguchi\n University"
]
] | Long-range forces up to next-to-leading order are computed in the framework of the Einstein-Maxwell-dilaton system by means of a semiclassical approach to gravity. As has been recently shown, this approach is effective if one of the masses under consideration is significantly greater than all the energies involved in the system. Further, we obtain the condition for the equilibrium of charged masses in the system. |
1309.3403 | Lisa Glaser | Lisa Glaser and Sumati Surya | Towards a Definition of Locality in a Manifoldlike Causal Set | 35 pages, 17 figures | Phys. Rev. D 88, 124026 (2013) | 10.1103/PhysRevD.88.124026 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is a common misconception that spacetime discreteness necessarily implies
a violation of local Lorentz invariance. In fact, in the causal set approach to
quantum gravity, Lorentz invariance follows from the specific implementation of
the discreteness hypothesis. However, this comes at the cost of locality. In
particular, it is difficult to define a "local" region in a manifoldlike causal
set, i.e., one that corresponds to an approximately flat spacetime region.
Following up on suggestions from previous work, we bridge this lacuna by
proposing a definition of locality based on the abundance of m-element
order-intervals as a function of m in a causal set. We obtain analytic
expressions for the expectation value of this function for an ensemble of
causal set that faithfully embeds into an Alexandrov interval in d-dimensional
Minkowski spacetime and use it to define local regions in a manifoldlike causal
set. We use this to argue that evidence of local regions is a necessary
condition for manifoldlikeness in a causal set. This in addition provides a new
continuum dimension estimator. We perform extensive simulations which support
our claims.
| [
{
"created": "Fri, 13 Sep 2013 09:06:37 GMT",
"version": "v1"
},
{
"created": "Mon, 7 Apr 2014 13:09:14 GMT",
"version": "v2"
}
] | 2014-04-08 | [
[
"Glaser",
"Lisa",
""
],
[
"Surya",
"Sumati",
""
]
] | It is a common misconception that spacetime discreteness necessarily implies a violation of local Lorentz invariance. In fact, in the causal set approach to quantum gravity, Lorentz invariance follows from the specific implementation of the discreteness hypothesis. However, this comes at the cost of locality. In particular, it is difficult to define a "local" region in a manifoldlike causal set, i.e., one that corresponds to an approximately flat spacetime region. Following up on suggestions from previous work, we bridge this lacuna by proposing a definition of locality based on the abundance of m-element order-intervals as a function of m in a causal set. We obtain analytic expressions for the expectation value of this function for an ensemble of causal set that faithfully embeds into an Alexandrov interval in d-dimensional Minkowski spacetime and use it to define local regions in a manifoldlike causal set. We use this to argue that evidence of local regions is a necessary condition for manifoldlikeness in a causal set. This in addition provides a new continuum dimension estimator. We perform extensive simulations which support our claims. |
2404.04013 | Sayak Datta | Sayak Datta, Richard Brito, Scott A. Hughes, Talya Klinger, Paolo Pani | Tidal heating as a discriminator for horizons in equatorial eccentric
extreme mass ratio inspirals | null | null | null | null | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | Tidal heating in a binary black hole system is driven by the absorption of
energy and angular momentum by the black hole's horizon. Previous works have
shown that this phenomenon becomes particularly significant during the late
stages of an extreme mass ratio inspiral (EMRI) into a rapidly spinning massive
black hole, a key focus for future low-frequency gravitational-wave
observations by (for instance) the LISA mission. Past analyses have largely
focused on quasi-circular inspiral geometry, with some of the most detailed
studies looking at equatorial cases. Though useful for illustrating the
physical principles, this limit is not very realistic astrophysically, since
the population of EMRI events is expected to arise from compact objects
scattered onto relativistic orbits in galactic centers through many-body
events. In this work, we extend those results by studying the importance of
tidal heating in equatorial EMRIs with generic eccentricities. Our results
suggest that accurate modeling of tidal heating is crucial to prevent
significant dephasing and systematic errors in EMRI parameter estimation. We
examine a phenomenological model for EMRIs around exotic compact objects by
parameterizing deviations from the black hole picture in terms of the fraction
of radiation absorbed compared to the BH case. Based on a mismatch calculation
we find that reflectivities as small as $|\mathcal{R}|^2 \sim
\mathcal{O}(10^{-5})$ are distinguishable from the BH case, irrespective of the
value of the eccentricity. We stress, however, that this finding should be
corroborated by future parameter estimation studies.
| [
{
"created": "Fri, 5 Apr 2024 10:40:20 GMT",
"version": "v1"
},
{
"created": "Sat, 27 Apr 2024 08:22:18 GMT",
"version": "v2"
},
{
"created": "Wed, 26 Jun 2024 07:28:14 GMT",
"version": "v3"
}
] | 2024-06-27 | [
[
"Datta",
"Sayak",
""
],
[
"Brito",
"Richard",
""
],
[
"Hughes",
"Scott A.",
""
],
[
"Klinger",
"Talya",
""
],
[
"Pani",
"Paolo",
""
]
] | Tidal heating in a binary black hole system is driven by the absorption of energy and angular momentum by the black hole's horizon. Previous works have shown that this phenomenon becomes particularly significant during the late stages of an extreme mass ratio inspiral (EMRI) into a rapidly spinning massive black hole, a key focus for future low-frequency gravitational-wave observations by (for instance) the LISA mission. Past analyses have largely focused on quasi-circular inspiral geometry, with some of the most detailed studies looking at equatorial cases. Though useful for illustrating the physical principles, this limit is not very realistic astrophysically, since the population of EMRI events is expected to arise from compact objects scattered onto relativistic orbits in galactic centers through many-body events. In this work, we extend those results by studying the importance of tidal heating in equatorial EMRIs with generic eccentricities. Our results suggest that accurate modeling of tidal heating is crucial to prevent significant dephasing and systematic errors in EMRI parameter estimation. We examine a phenomenological model for EMRIs around exotic compact objects by parameterizing deviations from the black hole picture in terms of the fraction of radiation absorbed compared to the BH case. Based on a mismatch calculation we find that reflectivities as small as $|\mathcal{R}|^2 \sim \mathcal{O}(10^{-5})$ are distinguishable from the BH case, irrespective of the value of the eccentricity. We stress, however, that this finding should be corroborated by future parameter estimation studies. |
1111.4824 | Frederic P. Schuller | Frederic P. Schuller | All spacetimes beyond Einstein (Obergurgl Lectures) | 44 pages, 7 figures, Lectures held for the Elitestudiengang Physik
Erlangen and Regensburg at Obergurgl/Austria, September 2011 | null | null | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Which geometries on a smooth manifold (apart from Lorentzian metrics) can
serve as a spacetime structure? This question is comprehensively addressed from
first principles in eight lectures, exploring the kinematics and gravitational
dynamics of all tensorial geometries on a smooth manifold that can carry
predictive matter equations, are time-orientable, and allow to distinguish
positive from negative particle energies.
| [
{
"created": "Mon, 21 Nov 2011 10:49:34 GMT",
"version": "v1"
}
] | 2011-11-22 | [
[
"Schuller",
"Frederic P.",
""
]
] | Which geometries on a smooth manifold (apart from Lorentzian metrics) can serve as a spacetime structure? This question is comprehensively addressed from first principles in eight lectures, exploring the kinematics and gravitational dynamics of all tensorial geometries on a smooth manifold that can carry predictive matter equations, are time-orientable, and allow to distinguish positive from negative particle energies. |
1405.7922 | Ramon Torres | R. Torres and F. Fayos | Singularity free gravitational collapse in an effective dynamical
quantum spacetime | 19 pages, 5 figures | Phys. Lett. B 733 (2014) 169-175 | 10.1016/j.physletb.2014.04.038 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We model the gravitational collapse of heavy massive shells including its
main quantum corrections. Among these corrections, quantum improvements coming
from Quantum Einstein Gravity are taken into account, which provides us with an
effective quantum spacetime. Likewise, we consider dynamical Hawking radiation
by modeling its back-reaction once the horizons have been generated. Our
results point towards a picture of gravitational collapse in which the
collapsing shell reaches a minimum non-zero radius (whose value depends on the
shell initial conditions) with its mass only slightly reduced. Then, there is
always a rebound after which most (or all) of the mass evaporates in the form
of Hawking radiation. Since the mass never concentrates in a single point, no
singularity appears.
| [
{
"created": "Fri, 30 May 2014 17:32:00 GMT",
"version": "v1"
}
] | 2015-06-19 | [
[
"Torres",
"R.",
""
],
[
"Fayos",
"F.",
""
]
] | We model the gravitational collapse of heavy massive shells including its main quantum corrections. Among these corrections, quantum improvements coming from Quantum Einstein Gravity are taken into account, which provides us with an effective quantum spacetime. Likewise, we consider dynamical Hawking radiation by modeling its back-reaction once the horizons have been generated. Our results point towards a picture of gravitational collapse in which the collapsing shell reaches a minimum non-zero radius (whose value depends on the shell initial conditions) with its mass only slightly reduced. Then, there is always a rebound after which most (or all) of the mass evaporates in the form of Hawking radiation. Since the mass never concentrates in a single point, no singularity appears. |
1406.0343 | Shaon Ghosh | Shaon Ghosh and Gijs Nelemans | Localizing gravitational wave sources with optical telescopes and
combining electromagnetic and gravitational wave data | 8 pages, 8 figures, Proceeding for Sant Cugat Forum for Astrophysics | null | 10.1007/978-3-319-10488-1_5 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Neutron star binaries, which are among the most promising sources for the
direct detection of gravitational waves (GW) by ground based detectors, are
also potential electromagnetic (EM) emitters. Gravitational waves will provide
a new window to observe these events and hopefully give us glimpses of new
astrophysics. In this paper, we discuss how EM information of these events can
considerably improve GW parameter estimation both in terms of accuracy and
computational power requirement. And then in return how GW sky localization can
help EM astronomers in follow-up studies of sources which did not yield any
prompt emission. We discuss how both EM source information and GW source
localization can be used in a framework of multi-messenger astronomy. We
illustrate how the large error regions in GW sky localizations can be handled
in conducting optical astronomy in the advance detector era. We show some
preliminary results in the context of an array of optical telescopes called
BlackGEM, dedicated for optical follow-up of GW triggers, that is being
constructed in La Silla, Chile and is expected to operate concurrent to the
advanced GW detectors.
| [
{
"created": "Mon, 2 Jun 2014 12:40:07 GMT",
"version": "v1"
}
] | 2015-06-19 | [
[
"Ghosh",
"Shaon",
""
],
[
"Nelemans",
"Gijs",
""
]
] | Neutron star binaries, which are among the most promising sources for the direct detection of gravitational waves (GW) by ground based detectors, are also potential electromagnetic (EM) emitters. Gravitational waves will provide a new window to observe these events and hopefully give us glimpses of new astrophysics. In this paper, we discuss how EM information of these events can considerably improve GW parameter estimation both in terms of accuracy and computational power requirement. And then in return how GW sky localization can help EM astronomers in follow-up studies of sources which did not yield any prompt emission. We discuss how both EM source information and GW source localization can be used in a framework of multi-messenger astronomy. We illustrate how the large error regions in GW sky localizations can be handled in conducting optical astronomy in the advance detector era. We show some preliminary results in the context of an array of optical telescopes called BlackGEM, dedicated for optical follow-up of GW triggers, that is being constructed in La Silla, Chile and is expected to operate concurrent to the advanced GW detectors. |
2204.12567 | Rafael Hern\'andez-Jim\'enez | Alejandro Casallas-Lagos, Claudia Moreno, Javier M. Antelis, Rafael
Hern\'andez-Jim\'enez | A search for distinctive footprints of compact binary coalescence within
alternatives theories of gravity | 19 pages, 7 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this review we examine the amplitude intensity associated to tensorial and
non-tensorial polarization modes generated by binary systems at their inspiral
stage, within the alternative theories of gravity of Brans Dicke, Rosen, and
Lightman Lee. This study is performed without making an explicit use of the
Transverse Traceless gauge of the General Relativity approach, and at the
Newtonian limit. Consequently such additional polarization modes appear
(non-tensorial) due to additional degrees of freedom in modified theories of
gravitation. We model and compare the different polarization modes and strain
signals for each scheme varying the sky location. Our analysis allows us to
identify the locations where these modes are more intense, and, therefore
susceptible to being identified for the future interferometer detector network.
This gives rise to a framework in which the amplitude and the intensity of all
polarization modes of general relativity and alternative hypotheses can be
compared.
| [
{
"created": "Tue, 26 Apr 2022 20:02:50 GMT",
"version": "v1"
},
{
"created": "Tue, 7 Jun 2022 02:25:56 GMT",
"version": "v2"
},
{
"created": "Mon, 2 Jan 2023 21:03:10 GMT",
"version": "v3"
},
{
"created": "Wed, 29 Mar 2023 19:31:44 GMT",
"version": "v4"
}
] | 2023-03-31 | [
[
"Casallas-Lagos",
"Alejandro",
""
],
[
"Moreno",
"Claudia",
""
],
[
"Antelis",
"Javier M.",
""
],
[
"Hernández-Jiménez",
"Rafael",
""
]
] | In this review we examine the amplitude intensity associated to tensorial and non-tensorial polarization modes generated by binary systems at their inspiral stage, within the alternative theories of gravity of Brans Dicke, Rosen, and Lightman Lee. This study is performed without making an explicit use of the Transverse Traceless gauge of the General Relativity approach, and at the Newtonian limit. Consequently such additional polarization modes appear (non-tensorial) due to additional degrees of freedom in modified theories of gravitation. We model and compare the different polarization modes and strain signals for each scheme varying the sky location. Our analysis allows us to identify the locations where these modes are more intense, and, therefore susceptible to being identified for the future interferometer detector network. This gives rise to a framework in which the amplitude and the intensity of all polarization modes of general relativity and alternative hypotheses can be compared. |
1012.2872 | Sean McWilliams | Sean T. McWilliams | The Status of Black-Hole Binary Merger Simulations with Numerical
Relativity | Invited review for NRDA/CAPRA 2010, CQG special issue - 7 pages, 1
figure, 1 table | null | 10.1088/0264-9381/28/13/134001 | null | gr-qc astro-ph.CO astro-ph.GA astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The advent of long-term stability in numerical relativity has yielded a
windfall of answers to long-standing questions regarding the dynamics of
space-time, matter, and electromagnetic fields in the strong-field regime of
black-hole binary mergers. In this review, we will briefly summarize the
methodology currently applied to these problems, emphasizing the most recent
advancements. We will discuss recent results of astrophysical relevance, and
present some novel interpretation. Though we primarily present a review, we
also present a simple analytical model for the time-dependent Poynting flux
from two orbiting black holes immersed in a magnetic field, which compares
favorably with recent numerical results. Finally, we will discuss recent
advancements in our theoretical understanding of merger dynamics and
gravitational waveforms that have resulted from interpreting the ever-growing
body of numerical relativity results.
| [
{
"created": "Mon, 13 Dec 2010 21:03:06 GMT",
"version": "v1"
}
] | 2015-05-20 | [
[
"McWilliams",
"Sean T.",
""
]
] | The advent of long-term stability in numerical relativity has yielded a windfall of answers to long-standing questions regarding the dynamics of space-time, matter, and electromagnetic fields in the strong-field regime of black-hole binary mergers. In this review, we will briefly summarize the methodology currently applied to these problems, emphasizing the most recent advancements. We will discuss recent results of astrophysical relevance, and present some novel interpretation. Though we primarily present a review, we also present a simple analytical model for the time-dependent Poynting flux from two orbiting black holes immersed in a magnetic field, which compares favorably with recent numerical results. Finally, we will discuss recent advancements in our theoretical understanding of merger dynamics and gravitational waveforms that have resulted from interpreting the ever-growing body of numerical relativity results. |
1411.3552 | Roldao da Rocha | Alex E. Bernardini, R. T. Cavalcanti, Roldao da Rocha | Spherically Symmetric Thick Branes Cosmological Evolution | 17 pages, Gen. Relat. Grav. (in press) | Gen. Relat. Grav. 47 (2014) 1840 | 10.1007/s10714-014-1840-x | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Spherically symmetric time-dependent solutions for the 5D system of a scalar
field canonically coupled to gravity are obtained and identified as an
extension of recent results obtained by Ahmed, Grzadkowskia and Wudkab. The
corresponding cosmology of models with regularized branes generated by such a
5D scalar field scenario is also investigated. It has been shown that the
anisotropic evolution of the warp factor and consequently the Hubble like
parameter are both driven by the radial coordinate on the brane, which leads to
an emergent thick brane-world scenario with spherically symmetric time
dependent warp factor. Meanwhile, the separability of variables depending on
fifth dimension, y, which is exhibited by the equations of motion, allows one
to recover the extra dimensional profiles obtained in the literature, namely
the extra dimensional part of the scale (warp) factor and the scalar field
dependence on y. Therefore, our results are mainly concerned with the time
dependence of a spherically symmetric warp factor. Besides evincing
possibilities for obtaining asymmetric stable brane-world scenarios, the extra
dimensional profiles here obtained can also be reduced to those ones
investigated in the literature.
| [
{
"created": "Thu, 13 Nov 2014 14:25:40 GMT",
"version": "v1"
}
] | 2014-12-31 | [
[
"Bernardini",
"Alex E.",
""
],
[
"Cavalcanti",
"R. T.",
""
],
[
"da Rocha",
"Roldao",
""
]
] | Spherically symmetric time-dependent solutions for the 5D system of a scalar field canonically coupled to gravity are obtained and identified as an extension of recent results obtained by Ahmed, Grzadkowskia and Wudkab. The corresponding cosmology of models with regularized branes generated by such a 5D scalar field scenario is also investigated. It has been shown that the anisotropic evolution of the warp factor and consequently the Hubble like parameter are both driven by the radial coordinate on the brane, which leads to an emergent thick brane-world scenario with spherically symmetric time dependent warp factor. Meanwhile, the separability of variables depending on fifth dimension, y, which is exhibited by the equations of motion, allows one to recover the extra dimensional profiles obtained in the literature, namely the extra dimensional part of the scale (warp) factor and the scalar field dependence on y. Therefore, our results are mainly concerned with the time dependence of a spherically symmetric warp factor. Besides evincing possibilities for obtaining asymmetric stable brane-world scenarios, the extra dimensional profiles here obtained can also be reduced to those ones investigated in the literature. |
gr-qc/0703047 | Farook Rahaman | F.Rahaman, S Chakraborty and J.Bera | Inhomogeneous Cosmological Model in Lyra Geometry | 7 pages, published in Int.J.Mod.Phys.D11, 1501 (2002) | Int.J.Mod.Phys.D11:1501,2002 | 10.1142/S0218271802001937 | null | gr-qc | null | Exact solutions are obtained for an inhomogeneous cosmological model in
normal gauge for Lyra geometry. Some properties of the model have also been
discussed.
| [
{
"created": "Wed, 7 Mar 2007 07:52:01 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Rahaman",
"F.",
""
],
[
"Chakraborty",
"S",
""
],
[
"Bera",
"J.",
""
]
] | Exact solutions are obtained for an inhomogeneous cosmological model in normal gauge for Lyra geometry. Some properties of the model have also been discussed. |
1809.05670 | J. W. van Holten | J.W. van Holten | Gravitational waves from generalized newtonian sources | 30 pages, 1 figure; update includes new appendix on gauge fixing and
improved figure; v3: the last expression in equation (76) is replaced by a
simpler and more useful one | Fortschritte der Physik (2019) 1800083 | 10.1002/prop.201800083 | null | gr-qc astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | I review the elementary theory of gravitational waves on a Minkowski
background and the quadrupole approximation. The modified conservation laws for
energy and momentum keeping track of the gravitational-wave flux are presented.
The theory is applied to two-body systems in bound and scattering states
subject to newtonian gravity generalized to include a 1/r3 force allowing for
orbital precession. The evolution of the orbits is studied in the adiabatic
approximation. From these results I derive the conditions for capture of two
bodies to form a bound state by the emission of gravitational radiation.
| [
{
"created": "Sat, 15 Sep 2018 08:22:05 GMT",
"version": "v1"
},
{
"created": "Fri, 16 Nov 2018 15:53:57 GMT",
"version": "v2"
},
{
"created": "Sun, 10 Feb 2019 14:23:06 GMT",
"version": "v3"
}
] | 2019-02-12 | [
[
"van Holten",
"J. W.",
""
]
] | I review the elementary theory of gravitational waves on a Minkowski background and the quadrupole approximation. The modified conservation laws for energy and momentum keeping track of the gravitational-wave flux are presented. The theory is applied to two-body systems in bound and scattering states subject to newtonian gravity generalized to include a 1/r3 force allowing for orbital precession. The evolution of the orbits is studied in the adiabatic approximation. From these results I derive the conditions for capture of two bodies to form a bound state by the emission of gravitational radiation. |
gr-qc/0605142 | Richard T. Hammond | Richard T Hammond | Geometrical Origin of the Cosmological Term | 7 pages | Int.J.Mod.Phys.D15:2159-2164,2006 | 10.1142/S0218271806009789 | null | gr-qc | null | Nonmetricity derived from a scalar field is shown to exist as a cosmic field,
without direct coupling to matter. It leads to a variable cosmological term, a
term that dominates the expansion in the early universe but dies away at later
time.
| [
{
"created": "Sat, 27 May 2006 20:53:16 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Hammond",
"Richard T",
""
]
] | Nonmetricity derived from a scalar field is shown to exist as a cosmic field, without direct coupling to matter. It leads to a variable cosmological term, a term that dominates the expansion in the early universe but dies away at later time. |
1801.04676 | Mingzhe Li | Yunlong Zheng, Yicen Mou, Haomin Rao, Mingzhe Li | Conformal invariant cosmological perturbations via the covariant
approach: multicomponent universe | 10 pages, the version to appear in Chinese Physics C | null | 10.1088/1674-1137/42/3/035102 | USTC-ICTS-17-14 | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In recent years there has been a lot of interest in discussing frame
dependences/independences of the cosmological perturbations under the conformal
transformations. This problem has previously been investigated in terms of the
covariant approach for a single component universe, and it was found that the
covariant approach is very powerful to pick out the perturbative variables
which are both gauge and conformal invariant. In this work, we extend the
covariant approach to a universe with multicomponent fluids. We find that
similar results can be derived, as expected. In addition, some other
interesting perturbations are also identified to be conformal invariant, such
as entropy perturbation between two different components.
| [
{
"created": "Mon, 15 Jan 2018 06:41:13 GMT",
"version": "v1"
},
{
"created": "Wed, 17 Jan 2018 09:02:45 GMT",
"version": "v2"
}
] | 2018-03-14 | [
[
"Zheng",
"Yunlong",
""
],
[
"Mou",
"Yicen",
""
],
[
"Rao",
"Haomin",
""
],
[
"Li",
"Mingzhe",
""
]
] | In recent years there has been a lot of interest in discussing frame dependences/independences of the cosmological perturbations under the conformal transformations. This problem has previously been investigated in terms of the covariant approach for a single component universe, and it was found that the covariant approach is very powerful to pick out the perturbative variables which are both gauge and conformal invariant. In this work, we extend the covariant approach to a universe with multicomponent fluids. We find that similar results can be derived, as expected. In addition, some other interesting perturbations are also identified to be conformal invariant, such as entropy perturbation between two different components. |
1905.08657 | David Garfinkle | Lydia Bieri, David Garfinkle and Shing-Tung Yau | A No-Boundary Method for Numerical Relativity | null | null | 10.1088/1361-6382/ab5e99 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose a method for numerical relativity in which the spatial grid is
finite and no outer boundary condition is needed. As a "proof of concept" we
implement this method for the case of a self-gravitating, spherically symmetric
scalar field.
| [
{
"created": "Tue, 21 May 2019 14:05:43 GMT",
"version": "v1"
}
] | 2020-02-12 | [
[
"Bieri",
"Lydia",
""
],
[
"Garfinkle",
"David",
""
],
[
"Yau",
"Shing-Tung",
""
]
] | We propose a method for numerical relativity in which the spatial grid is finite and no outer boundary condition is needed. As a "proof of concept" we implement this method for the case of a self-gravitating, spherically symmetric scalar field. |
gr-qc/0311084 | Jean-Paul Mbelek | J. P. Mbelek | 5D gravity and the discrepant G measurements | 13 pages, to be published in: Proceedings of the 18th Course of the
School on Cosmology and Gravitation: The gravitational Constant. Generalized
gravitational theories and experiments (30 April-10 May 2003, Erice). Ed. by
G. T. Gillies, V. N. Melnikov and V. de Sabbata, (Kluwer), 13pp. (in print)
(2003) | null | 10.1007/978-1-4020-2242-5_11 | null | gr-qc | null | It is shown that 5D Kaluza-Klein theory stabilized by an external bulk scalar
field may solve the discrepant laboratory G measurements. This is achieved by
an effective coupling between gravitation and the geomagnetic field.
Experimental considerations are also addressed.
| [
{
"created": "Wed, 26 Nov 2003 15:50:48 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Mbelek",
"J. P.",
""
]
] | It is shown that 5D Kaluza-Klein theory stabilized by an external bulk scalar field may solve the discrepant laboratory G measurements. This is achieved by an effective coupling between gravitation and the geomagnetic field. Experimental considerations are also addressed. |
1302.4831 | Kazuharu Bamba | Kazuharu Bamba, Shin'ichi Nojiri and Sergei D. Odintsov | Modified gravity: walk through accelerating cosmology | 16 pages, no figure, to appear in: Proceedings of the 7th
Mathematical Physics Meeting: Summer School and Conference on Modern
Mathematical Physics (Sept. 9--19, 2012, Belgrade, Serbia). Editors B.
Dragovich and Z. Rakic. Published by Institute of Physics, Belgrade 2013,
Serbia | null | null | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We review the accelerating (mainly, dark energy) cosmologies in modified
gravity. Special attention is paid to cosmologies leading to finite-time future
singularities in $F(R)$, $F(G)$ and $\mathcal{F}(R,G)$ modified gravities. The
removal of the finite-time future singularities via addition of $R^2$-term
which simultaneously unifies the early-time inflation with late-time
acceleration is also briefly mentioned. Accelerating cosmology including the
scenario unifying inflation with dark energy is considered in $F(R)$ gravity
with Lagrange multipliers. In addition, we examine domain wall solutions in
$F(R)$ gravity. Furthermore, covariant higher derivative gravity with scalar
projectors is explored.
| [
{
"created": "Wed, 20 Feb 2013 08:28:29 GMT",
"version": "v1"
}
] | 2013-02-21 | [
[
"Bamba",
"Kazuharu",
""
],
[
"Nojiri",
"Shin'ichi",
""
],
[
"Odintsov",
"Sergei D.",
""
]
] | We review the accelerating (mainly, dark energy) cosmologies in modified gravity. Special attention is paid to cosmologies leading to finite-time future singularities in $F(R)$, $F(G)$ and $\mathcal{F}(R,G)$ modified gravities. The removal of the finite-time future singularities via addition of $R^2$-term which simultaneously unifies the early-time inflation with late-time acceleration is also briefly mentioned. Accelerating cosmology including the scenario unifying inflation with dark energy is considered in $F(R)$ gravity with Lagrange multipliers. In addition, we examine domain wall solutions in $F(R)$ gravity. Furthermore, covariant higher derivative gravity with scalar projectors is explored. |
gr-qc/0604085 | Thomas Marlow | Thomas Marlow | Weak Values and Relational Generalisations | 11 pages, contains a reworking of an argument in gr-qc/0603015 | null | null | null | gr-qc | null | We justify generalisations of weak values from a tentatively relational
perspective by deriving them from a generalisation of Bayes' rule. We also
argue that these generalisations have implications of quantum nonlocality and
may form a novel approach to quantum gravity and cosmology.
| [
{
"created": "Thu, 20 Apr 2006 09:24:25 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Marlow",
"Thomas",
""
]
] | We justify generalisations of weak values from a tentatively relational perspective by deriving them from a generalisation of Bayes' rule. We also argue that these generalisations have implications of quantum nonlocality and may form a novel approach to quantum gravity and cosmology. |
2003.10831 | Z. Yousaf | Z. Yousaf, M. Z. Bhatti, T. Naseer | New Definition of Complexity Factor in $f(R,T,R_{\mu\nu}T^{\mu\nu})$
Gravity | 26 pages | Phys. Dark Universe 28, 100535 (2020) | 10.1016/j.dark.2020.100535 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper is devoted to present new definition of complexity factor for
static cylindrically symmetric matter configurations in
$f(R,T,R_{\mu\nu}T^{\mu\nu})$ gravity. For this purpose, we have considered
irrotational static cylindrical spacetime coupled with a locally anisotropic
relativistic fluid. After formulating gravitational field and conservation
equations, we have performed orthogonal splitting of the Riemann curvature
tensor. Unlike GR (for spherical case) the one of the structure scalars
$X_{TF}$, has been identified to be a complexity factor. This factor contains
effective forms of the energy density, and anisotropic pressure components. Few
peculiar relations among complexity factor, Tolman mass and Weyl scalar are
also analyzed with the modified $f(R,T,R_{\mu\nu}T^{\mu\nu})$ corrections.
| [
{
"created": "Sat, 21 Mar 2020 09:45:49 GMT",
"version": "v1"
}
] | 2020-03-30 | [
[
"Yousaf",
"Z.",
""
],
[
"Bhatti",
"M. Z.",
""
],
[
"Naseer",
"T.",
""
]
] | This paper is devoted to present new definition of complexity factor for static cylindrically symmetric matter configurations in $f(R,T,R_{\mu\nu}T^{\mu\nu})$ gravity. For this purpose, we have considered irrotational static cylindrical spacetime coupled with a locally anisotropic relativistic fluid. After formulating gravitational field and conservation equations, we have performed orthogonal splitting of the Riemann curvature tensor. Unlike GR (for spherical case) the one of the structure scalars $X_{TF}$, has been identified to be a complexity factor. This factor contains effective forms of the energy density, and anisotropic pressure components. Few peculiar relations among complexity factor, Tolman mass and Weyl scalar are also analyzed with the modified $f(R,T,R_{\mu\nu}T^{\mu\nu})$ corrections. |
gr-qc/0609085 | Sergiu Vacaru I. | Sergiu I. Vacaru and Mihai Visinescu | Nonholonomic Ricci Flows and Running Cosmological Constant: I. 4D
Taub-NUT Metrics | latex2e, final variant to be published in IJMPA | Int.J.Mod.Phys.A22:1135-1160,2007 | 10.1142/S0217751X07035045 | null | gr-qc hep-th math-ph math.DG math.MP | null | In this work we construct and analyze exact solutions describing Ricci flows
and nonholonomic deformations of four dimensional (4D) Taub-NUT spacetimes. It
is outlined a new geometric techniques of constructing Ricci flow solutions.
Some conceptual issues on spacetimes provided with generic off-diagonal metrics
and associated nonlinear connection structures are analyzed. The limit from
gravity/Ricci flow models with nontrivial torsion to configurations with the
Levi-Civita connection is allowed in some specific physical circumstances by
constraining the class of integral varieties for the Einstein and Ricci flow
equations.
| [
{
"created": "Wed, 20 Sep 2006 18:57:44 GMT",
"version": "v1"
},
{
"created": "Fri, 2 Feb 2007 18:16:50 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Vacaru",
"Sergiu I.",
""
],
[
"Visinescu",
"Mihai",
""
]
] | In this work we construct and analyze exact solutions describing Ricci flows and nonholonomic deformations of four dimensional (4D) Taub-NUT spacetimes. It is outlined a new geometric techniques of constructing Ricci flow solutions. Some conceptual issues on spacetimes provided with generic off-diagonal metrics and associated nonlinear connection structures are analyzed. The limit from gravity/Ricci flow models with nontrivial torsion to configurations with the Levi-Civita connection is allowed in some specific physical circumstances by constraining the class of integral varieties for the Einstein and Ricci flow equations. |
gr-qc/0506034 | Romualdo Tresguerres | Alfredo Tiemblo and Romualdo Tresguerres | Gravitational contribution to fermion masses | revtex4, 9 pages, no figures, to be published in Eur.Phys.J.C, 2005 | Eur.Phys.J.C42:437-444,2005 | 10.1140/epjc/s2005-02312-0 | null | gr-qc hep-th math-ph math.MP | null | In the context of a nonlinear gauge theory of the Poincar\'e group, we show
that covariant derivatives of Dirac fields include a coupling to the
translational connections, manifesting itself in the matter action as a
universal background mass contribution to fermions.
| [
{
"created": "Mon, 6 Jun 2005 15:10:03 GMT",
"version": "v1"
}
] | 2009-01-07 | [
[
"Tiemblo",
"Alfredo",
""
],
[
"Tresguerres",
"Romualdo",
""
]
] | In the context of a nonlinear gauge theory of the Poincar\'e group, we show that covariant derivatives of Dirac fields include a coupling to the translational connections, manifesting itself in the matter action as a universal background mass contribution to fermions. |
2307.10958 | William H. Kinney | William H. Kinney (Univ. at Buffalo, SUNY, USA), Suvashis Maity, L.
Sriramkumar (Indian Insitute of Technology, Madras, India) | The Borde-Guth-Vilenkin Theorem in extended de Sitter spaces | 23 pages, 4 figures (V2: Matches version accepted for publication in
Phys. Rev. D) | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Borde-Guth-Vilenkin (BGV) theorem states that any spacetime with net
positive expansion must be geodesically incomplete. We derive a new version of
the theorem using the fluid flow formalism of General Relativity. The theorem
is purely kinematic, depending on the local expansion properties of geodesics,
and makes no assumptions about energy conditions. We discuss the physical
interpretation of this result in terms of coordinate patches on de Sitter
space, and apply the theorem to Penrose's model of Conformal Cyclic Cosmology.
We argue that the Conformal Cyclic extension of an asymptotically de Sitter
universe is geodesically incomplete.
| [
{
"created": "Thu, 20 Jul 2023 15:30:35 GMT",
"version": "v1"
},
{
"created": "Tue, 6 Feb 2024 21:22:07 GMT",
"version": "v2"
}
] | 2024-02-08 | [
[
"Kinney",
"William H.",
"",
"Univ. at Buffalo, SUNY, USA"
],
[
"Maity",
"Suvashis",
"",
"Indian Insitute of Technology, Madras, India"
],
[
"Sriramkumar",
"L.",
"",
"Indian Insitute of Technology, Madras, India"
]
] | The Borde-Guth-Vilenkin (BGV) theorem states that any spacetime with net positive expansion must be geodesically incomplete. We derive a new version of the theorem using the fluid flow formalism of General Relativity. The theorem is purely kinematic, depending on the local expansion properties of geodesics, and makes no assumptions about energy conditions. We discuss the physical interpretation of this result in terms of coordinate patches on de Sitter space, and apply the theorem to Penrose's model of Conformal Cyclic Cosmology. We argue that the Conformal Cyclic extension of an asymptotically de Sitter universe is geodesically incomplete. |
2207.14546 | Naimi Takka | N. Takka | Exact form of the generalized Lorentz force in Fock's nonlinear
relativity | null | Int. J. Mod. Phys. A34, 1950016 (2019) | 10.1142/S0217751X19500167 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | This work completes a serie of two papers devoted to the extension of the
fundamental laws of electrodynamics in the context of Fock's nonlinear
relativity (FNLR). Indeed, after having established in the previous study the
exact generalizations of both Maxwell's equations and Dirac magnetic monopole,
we present here the remaining exact Lorentz force. As in k-Minkowski spacetime,
two different nature contributions appear in the corresponding equation of
motion where the new effect is interpreted as the gravitational-type Lorentz
force. This common point separately induced by the radius of the universe in
our case or Planck energy in other works, reinforces once more the analogy
between electromagnetism and gravity in two different scientific approaches. As
a relative difference, it is very important to highlight that more homogeneity
characterizes our results where each effect is exclusively generated by mass or
charge but not both at the same time. Even more, the new effect emerges as the
result of the triple effect of R-deformation, mass and the square of velocities
but completely independent of electromagnetic field.
| [
{
"created": "Fri, 29 Jul 2022 08:28:22 GMT",
"version": "v1"
}
] | 2022-08-01 | [
[
"Takka",
"N.",
""
]
] | This work completes a serie of two papers devoted to the extension of the fundamental laws of electrodynamics in the context of Fock's nonlinear relativity (FNLR). Indeed, after having established in the previous study the exact generalizations of both Maxwell's equations and Dirac magnetic monopole, we present here the remaining exact Lorentz force. As in k-Minkowski spacetime, two different nature contributions appear in the corresponding equation of motion where the new effect is interpreted as the gravitational-type Lorentz force. This common point separately induced by the radius of the universe in our case or Planck energy in other works, reinforces once more the analogy between electromagnetism and gravity in two different scientific approaches. As a relative difference, it is very important to highlight that more homogeneity characterizes our results where each effect is exclusively generated by mass or charge but not both at the same time. Even more, the new effect emerges as the result of the triple effect of R-deformation, mass and the square of velocities but completely independent of electromagnetic field. |
1904.00280 | Geoffrey Comp\`ere | Geoffrey Comp\`ere | Infinite towers of supertranslation and superrotation memories | 5 pages. Proof of existence of towers of memories added. To be
published in PRL | Phys. Rev. Lett. 123, 021101 (2019) | 10.1103/PhysRevLett.123.021101 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A framework that structures the gravitational memory effects and which is
consistent with gravitational electric-magnetic duality is presented. A
correspondence is described between memory observables, particular subleading
residual gauge transformations, associated overleading gauge transformations
and their canonical surface charges. It is shown that matter-induced
transitions can generate infinite towers of independent memory effects at null
infinity. These memories are associated with an infinite number of conservation
laws at spatial infinity which lead to degenerate towers of subleading soft
graviton theorems. It is shown that the leading order mutually commuting
supertranslations and (novel) superrotations are both associated with a leading
displacement memory effect, which suggests the existence of new boundary
conditions.
| [
{
"created": "Sat, 30 Mar 2019 20:24:32 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Jul 2019 09:23:47 GMT",
"version": "v2"
}
] | 2019-07-17 | [
[
"Compère",
"Geoffrey",
""
]
] | A framework that structures the gravitational memory effects and which is consistent with gravitational electric-magnetic duality is presented. A correspondence is described between memory observables, particular subleading residual gauge transformations, associated overleading gauge transformations and their canonical surface charges. It is shown that matter-induced transitions can generate infinite towers of independent memory effects at null infinity. These memories are associated with an infinite number of conservation laws at spatial infinity which lead to degenerate towers of subleading soft graviton theorems. It is shown that the leading order mutually commuting supertranslations and (novel) superrotations are both associated with a leading displacement memory effect, which suggests the existence of new boundary conditions. |
1609.03022 | Kota Ogasawara | Kota Ogasawara, Tomohiro Harada, Umpei Miyamoto, Takahisa Igata | Escape probability of the super-Penrose process | 5pages, 2figures | Phys. Rev. D 95, 124019 (2017) | 10.1103/PhysRevD.95.124019 | RUP-16-26 | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a head-on collision of two massive particles that move in the
equatorial plane of an extremal Kerr black hole, which results in the
production of two massless particles. Focusing on a typical case, where both of
the colliding particles have zero angular momenta, we show that a massless
particle produced in such a collision can escape to infinity with arbitrarily
large energy in the near-horizon limit of the collision point. Furthermore, if
we assume that the emission of the produced massless particles is isotropic in
the center-of-mass frame but confined to the equatorial plane, the escape
probability of the produced massless particle approaches $5/12$ and almost all
escaping massless particles have arbitrarily large energy at infinity and an
impact parameter approaching $2GM/c^2$, where $M$ is the mass of the black
hole.
| [
{
"created": "Sat, 10 Sep 2016 09:55:59 GMT",
"version": "v1"
},
{
"created": "Wed, 21 Jun 2017 07:36:45 GMT",
"version": "v2"
}
] | 2017-06-22 | [
[
"Ogasawara",
"Kota",
""
],
[
"Harada",
"Tomohiro",
""
],
[
"Miyamoto",
"Umpei",
""
],
[
"Igata",
"Takahisa",
""
]
] | We consider a head-on collision of two massive particles that move in the equatorial plane of an extremal Kerr black hole, which results in the production of two massless particles. Focusing on a typical case, where both of the colliding particles have zero angular momenta, we show that a massless particle produced in such a collision can escape to infinity with arbitrarily large energy in the near-horizon limit of the collision point. Furthermore, if we assume that the emission of the produced massless particles is isotropic in the center-of-mass frame but confined to the equatorial plane, the escape probability of the produced massless particle approaches $5/12$ and almost all escaping massless particles have arbitrarily large energy at infinity and an impact parameter approaching $2GM/c^2$, where $M$ is the mass of the black hole. |
1406.5524 | Parthasarathi Mitra | P. Mitra | Black hole entropy with and without log correction in loop quantum
gravity | 6 pages; talk delivered at Light Cone conference, Delhi, 2012, to
appear in Nucl. Phys. B [PS] 251-252 (2014) | Nucl. Phys. B [Proc. Suppl.] 251-252 (2014) 87 | 10.1016/j.nuclphysbps.2014.04.015 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Earlier calculations of black hole entropy in loop quantum gravity have given
a term proportional to the area with a correction involving the logarithm of
the area when the area eigenvalue is close to the classical area. However the
calculations yield an entropy proportional to the area eigenvalue with no such
correction when the area eigenvalue is large compared to the classical area.
| [
{
"created": "Mon, 2 Jun 2014 04:52:50 GMT",
"version": "v1"
}
] | 2014-06-25 | [
[
"Mitra",
"P.",
""
]
] | Earlier calculations of black hole entropy in loop quantum gravity have given a term proportional to the area with a correction involving the logarithm of the area when the area eigenvalue is close to the classical area. However the calculations yield an entropy proportional to the area eigenvalue with no such correction when the area eigenvalue is large compared to the classical area. |
gr-qc/9508048 | null | R.D. Daniels and G.M. Shore | `Faster than light' photons and rotating black holes | Plain TeX, 12 pages, 1 figure | Phys.Lett. B367 (1996) 75-83 | 10.1016/0370-2693(95)01468-3 | SWAT 95/71 CERN-TH/95-229 | gr-qc hep-th | null | The effective action for QED in curved spacetime includes equivalence
principle violating interactions between the electromagnetic field and the
spacetime curvature. These interactions admit the possibility of superluminal
yet causal photon propagation in gravitational fields. In this paper, we extend
our analysis of photon propagation in gravitational backgrounds to the Kerr
spacetime describing a rotating black hole. The results support two general
theorems -- a polarisation sum rule and a `horizon theorem'. The implications
for the stationary limit surface bounding the ergosphere are also discussed.
| [
{
"created": "Tue, 22 Aug 1995 14:36:46 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Daniels",
"R. D.",
""
],
[
"Shore",
"G. M.",
""
]
] | The effective action for QED in curved spacetime includes equivalence principle violating interactions between the electromagnetic field and the spacetime curvature. These interactions admit the possibility of superluminal yet causal photon propagation in gravitational fields. In this paper, we extend our analysis of photon propagation in gravitational backgrounds to the Kerr spacetime describing a rotating black hole. The results support two general theorems -- a polarisation sum rule and a `horizon theorem'. The implications for the stationary limit surface bounding the ergosphere are also discussed. |
1303.5593 | Rabin Banerjee | Rabin Banerjee | Exact results in two dimensional chiral hydrodynamics with gravitational
anomalies | 9 pages, Expanded version, Couple of equations modified, new
reference added; minor textual changes and new equations added in the final
version, To appear in EPJC | null | 10.1140/epjc/s10052-014-2824-4 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An exact formulation of two dimensional chiral hydrodynamics with
diffeomorphism and conformal anomalies is provided. The constitutive relation
involving the stress tensor is computed. It reveals a one parameter class of
solutions which is a new result. For a particular value of this parameter, the
results found in the gradient expansion scheme are reproduced. Moreover, the
constitutive relation is analogous to the corresponding relation for an ideal
fluid, appropriately modified to include the chirality property, which has also
been derived here.
| [
{
"created": "Fri, 22 Mar 2013 12:15:05 GMT",
"version": "v1"
},
{
"created": "Fri, 26 Apr 2013 12:35:24 GMT",
"version": "v2"
},
{
"created": "Fri, 21 Mar 2014 05:52:57 GMT",
"version": "v3"
}
] | 2014-03-24 | [
[
"Banerjee",
"Rabin",
""
]
] | An exact formulation of two dimensional chiral hydrodynamics with diffeomorphism and conformal anomalies is provided. The constitutive relation involving the stress tensor is computed. It reveals a one parameter class of solutions which is a new result. For a particular value of this parameter, the results found in the gradient expansion scheme are reproduced. Moreover, the constitutive relation is analogous to the corresponding relation for an ideal fluid, appropriately modified to include the chirality property, which has also been derived here. |
1712.05675 | Giuseppe Fanizza | Ermis Mitsou, Fulvio Scaccabarozzi and Giuseppe Fanizza | Observed Angles and Geodesic Light-Cone Coordinates | 6 pages, final version accepted for publication in Classical and
Quantum Gravity | Class.Quant.Grav. 35 (2018) no.10, 107002 | 10.1088/1361-6382/aab06b | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss the interpretation of the angles in the Geodesic Light-Cone (GLC)
coordinates. In particular, we clarify the way in which these angles can be
identified with the observed ones. We show that, although this identification
is always possible in principle, one cannot implement it in the usual
gauge-fixing way, i.e. through a set of conditions on the GLC metric. Rather,
one needs to invoke a tetrad at the observer and a Cartesian-like coordinate
system in order to obtain the desired map globally on the observed sky.
| [
{
"created": "Fri, 15 Dec 2017 13:52:07 GMT",
"version": "v1"
},
{
"created": "Tue, 17 Apr 2018 09:43:22 GMT",
"version": "v2"
}
] | 2018-04-18 | [
[
"Mitsou",
"Ermis",
""
],
[
"Scaccabarozzi",
"Fulvio",
""
],
[
"Fanizza",
"Giuseppe",
""
]
] | We discuss the interpretation of the angles in the Geodesic Light-Cone (GLC) coordinates. In particular, we clarify the way in which these angles can be identified with the observed ones. We show that, although this identification is always possible in principle, one cannot implement it in the usual gauge-fixing way, i.e. through a set of conditions on the GLC metric. Rather, one needs to invoke a tetrad at the observer and a Cartesian-like coordinate system in order to obtain the desired map globally on the observed sky. |
2207.00631 | Vyacheslav Vandeev | V.P. Vandeev, A.N. Semenova | Tidal properties of D-dimensional Tangherlini black holes | 17 pages. Indian J Phys (2022) | null | 10.1007/s12648-022-02543-5 | null | gr-qc | http://creativecommons.org/publicdomain/zero/1.0/ | This paper investigates tidal forces in multidimensional spherically
symmetric spacetimes. We consider geodesic deviation equation in
Schwarzschild-Tangherlini metric and its electrically charged analog. It was
shown that for radial geodesics these equations can be solved explicitly as
quadratures in spaces of any dimension. In the case of five, six and seven
dimensional spaces, these solutions can be represented in terms of elliptic
integrals. For spacetimes of higher dimension, we find the asymptotics of the
solution. It was found that in the physical singularity vicinity tidal stretch
along the radial direction is the stronger the greater the dimension of space.
Whereas the tidal compression in transverse to radial directions, starting from
a certain dimension, does not change in the main order. Also in the case of
non-radial geodesics, the presence of black hole electric charge does not
affect the force of transverse compression in the leading order. For non-radial
geodesics with non-zero angular momentum, the local properties of solutions of
geodesic deviation equations in the vicinity of a singularity are studied.
| [
{
"created": "Fri, 1 Jul 2022 19:15:26 GMT",
"version": "v1"
}
] | 2023-01-09 | [
[
"Vandeev",
"V. P.",
""
],
[
"Semenova",
"A. N.",
""
]
] | This paper investigates tidal forces in multidimensional spherically symmetric spacetimes. We consider geodesic deviation equation in Schwarzschild-Tangherlini metric and its electrically charged analog. It was shown that for radial geodesics these equations can be solved explicitly as quadratures in spaces of any dimension. In the case of five, six and seven dimensional spaces, these solutions can be represented in terms of elliptic integrals. For spacetimes of higher dimension, we find the asymptotics of the solution. It was found that in the physical singularity vicinity tidal stretch along the radial direction is the stronger the greater the dimension of space. Whereas the tidal compression in transverse to radial directions, starting from a certain dimension, does not change in the main order. Also in the case of non-radial geodesics, the presence of black hole electric charge does not affect the force of transverse compression in the leading order. For non-radial geodesics with non-zero angular momentum, the local properties of solutions of geodesic deviation equations in the vicinity of a singularity are studied. |
gr-qc/9807030 | Ernest Tagirov | E.A.Tagirov | Quantum Mechanics in General Relativity | 22 pages | null | null | null | gr-qc | null | Having started with the general formulation of the quantum theory of the real
scalar field (QFT) in the general Riemannian space--time $ V_{1,3} $, the
general--covariant quasinonrelativistic quantum mechanics of a point-like
spinless particle in $ V_{1,3} $ is constructed. To this end, for any normal
geodesic 1+3--foliation of $ V_{1,3} $, a space $\Phi^-$ of asymptotic in
$c^{-1}$ solutions of the field equation is specified, which can be mapped to a
space $\Psi$ of solutions of a Schr\"odinger equation with an (asymptotically)
Hermitean hamiltonian and the Born probabilistic interpretation of the vectors
of $\Psi$. The basic operators of the momentum and the spatial position of the
particle acting in $\Psi$ generated by the corresponding observables of QFT
include relativistic corrections, and therefore differ generally from those
which follow for the geodesic motion in $ V_{1,3} $ from the canonical
postulates of quantization. In particular, the operators of coordinates do not
commute as well as the operators of the conjugate momenta, except the cases of
Cartesian coordinates in the Minkowski space--time or of the exact
nonrelativistic limit $(c^{-1} = 0)$. This approach provides QFT in the general
$ V_{1,3} $ in the Fock representation with a particle interpretation based on
the Born interpretation of wave functions.
| [
{
"created": "Tue, 14 Jul 1998 20:32:26 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Tagirov",
"E. A.",
""
]
] | Having started with the general formulation of the quantum theory of the real scalar field (QFT) in the general Riemannian space--time $ V_{1,3} $, the general--covariant quasinonrelativistic quantum mechanics of a point-like spinless particle in $ V_{1,3} $ is constructed. To this end, for any normal geodesic 1+3--foliation of $ V_{1,3} $, a space $\Phi^-$ of asymptotic in $c^{-1}$ solutions of the field equation is specified, which can be mapped to a space $\Psi$ of solutions of a Schr\"odinger equation with an (asymptotically) Hermitean hamiltonian and the Born probabilistic interpretation of the vectors of $\Psi$. The basic operators of the momentum and the spatial position of the particle acting in $\Psi$ generated by the corresponding observables of QFT include relativistic corrections, and therefore differ generally from those which follow for the geodesic motion in $ V_{1,3} $ from the canonical postulates of quantization. In particular, the operators of coordinates do not commute as well as the operators of the conjugate momenta, except the cases of Cartesian coordinates in the Minkowski space--time or of the exact nonrelativistic limit $(c^{-1} = 0)$. This approach provides QFT in the general $ V_{1,3} $ in the Fock representation with a particle interpretation based on the Born interpretation of wave functions. |
1709.09573 | Behnam Pourhassan | Behnam Pourhassan, Mir Faizal, Zaid Zaz, and Anha Bhat | Quantum Fluctuations of a BTZ Black Hole in Massive Gravity | Accepted for publication in PLB | Phys. Lett. B 773 (2017) 325 | 10.1016/j.physletb.2017.08.046 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we shall analyze the effects of quantum fluctuations on the
properties of a BTZ black hole, in a massive theory of gravity. We will analyze
this for a charged BTZ black hole in asymptotically AdS and dS space-times. The
quantum fluctuations would produce thermal fluctuations in the thermodynamics
of this BTZ black hole. As these fluctuations would become relevant at a
sufficiently small scale, we shall discuss the effects of such thermal
fluctuations on the entropy of a small charged BTZ black. We shall also analyze
the effects of these fluctuations on the stability of such a black hole.
| [
{
"created": "Tue, 12 Sep 2017 04:06:00 GMT",
"version": "v1"
}
] | 2017-10-17 | [
[
"Pourhassan",
"Behnam",
""
],
[
"Faizal",
"Mir",
""
],
[
"Zaz",
"Zaid",
""
],
[
"Bhat",
"Anha",
""
]
] | In this work, we shall analyze the effects of quantum fluctuations on the properties of a BTZ black hole, in a massive theory of gravity. We will analyze this for a charged BTZ black hole in asymptotically AdS and dS space-times. The quantum fluctuations would produce thermal fluctuations in the thermodynamics of this BTZ black hole. As these fluctuations would become relevant at a sufficiently small scale, we shall discuss the effects of such thermal fluctuations on the entropy of a small charged BTZ black. We shall also analyze the effects of these fluctuations on the stability of such a black hole. |
1606.04044 | Tim Koslowski A | Joseph Ben Geloun, Tim A. Koslowski | Nontrivial UV behavior of rank-4 tensor field models for quantum gravity | Latex, 4 pages + references | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the universality classes of rank-4 colored bipartite U(1)
tensor field models near the Gaussian fixed point with the functional
renormalization group. In a truncation that contains all power counting
relevant and marginal operators, we find a one-dimensional UV attractor that is
connected with the Gaussian fixed point. Hence this is first evidence that the
model could be asymptotically safe due to a mechanism similar to the one found
in the Grosse-Wulkenhaar model, whose UV behavior near the Gaussian fixed point
is also described by one-dimensional attractor that contains the Gaussian fixed
point. However, the cancellation mechanism that is responsible for the
simultaneous vanishing of the beta functions is new to tensor models, i.e. it
does not occur in vector or matrix models.
| [
{
"created": "Mon, 13 Jun 2016 17:31:02 GMT",
"version": "v1"
}
] | 2016-06-14 | [
[
"Geloun",
"Joseph Ben",
""
],
[
"Koslowski",
"Tim A.",
""
]
] | We investigate the universality classes of rank-4 colored bipartite U(1) tensor field models near the Gaussian fixed point with the functional renormalization group. In a truncation that contains all power counting relevant and marginal operators, we find a one-dimensional UV attractor that is connected with the Gaussian fixed point. Hence this is first evidence that the model could be asymptotically safe due to a mechanism similar to the one found in the Grosse-Wulkenhaar model, whose UV behavior near the Gaussian fixed point is also described by one-dimensional attractor that contains the Gaussian fixed point. However, the cancellation mechanism that is responsible for the simultaneous vanishing of the beta functions is new to tensor models, i.e. it does not occur in vector or matrix models. |
1609.00826 | Peter K.F. Kuhfittig | Peter K. F. Kuhfittig | The effect of conformal symmetry on charged wormholes | 10 pages, 1 figure | JAMP, vol. 4, pp. 2117-2125, 2016 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper discusses the effect that conformal symmetry can have on a charged
wormhole. The analysis yields a physical interpretation of the conformal factor
in terms of the electric charge. The rate of change of the conformal factor
determines much of the outcome, which ranges from having no solution to
wormholes having either one or two throats.
| [
{
"created": "Sat, 3 Sep 2016 13:21:50 GMT",
"version": "v1"
},
{
"created": "Wed, 7 Dec 2016 20:10:35 GMT",
"version": "v2"
}
] | 2016-12-08 | [
[
"Kuhfittig",
"Peter K. F.",
""
]
] | This paper discusses the effect that conformal symmetry can have on a charged wormhole. The analysis yields a physical interpretation of the conformal factor in terms of the electric charge. The rate of change of the conformal factor determines much of the outcome, which ranges from having no solution to wormholes having either one or two throats. |
gr-qc/9801031 | Perjes Zoltan | L\'aszl\'o \'A. Gergely, Zolt\'an I. Perj\'es and M\'aty\'as Vas\'uth
(KFKI RMKI, Budapest) | Spin effects in gravitational radiation backreaction II. Finite mass
effects | 12 pages, 1 figure, Phys.Rev.D15, March, 1998 | Phys.Rev. D57 (1998) 3423-3432 | 10.1103/PhysRevD.57.3423 | null | gr-qc | null | A convenient formalism for averaging the losses produced by gravitational
radiation backreaction over one orbital period was developed in an earlier
paper. In the present paper we generalize this formalism to include the case of
a closed system composed from two bodies of comparable masses, one of them
having the spin S.
We employ the equations of motion given by Barker and O'Connell, where terms
up to linear order in the spin (the spin-orbit interaction terms) are kept. To
obtain the radiative losses up to terms linear in the spin, the equations of
motion are taken to the same order. Then the magnitude L of the angular
momentum L, the angle kappa subtended by S and L and the energy E are
conserved. The analysis of the radial motion leads to a new parametrization of
the orbit.
From the instantaneous gravitational radiation losses computed by Kidder the
leading terms and the spin-orbit terms are taken. Following Apostolatos,
Cutler, Sussman and Thorne, the evolution of the vectors S and L in the
momentary plane spanned by these vectors is separated from the evolution of the
plane in space. The radiation-induced change in the spin is smaller than the
leading-order spin terms in the momentary angular momentum loss. This enables
us to compute the averaged losses in the constants of motion E, L and L_S=L cos
kappa. In the latter, the radiative spin loss terms average to zero. An
alternative description using the orbital elements a,e and kappa is given.
The finite mass effects contribute terms, comparable in magnitude, to the
basic, test-particle spin terms in the averaged losses.
| [
{
"created": "Sat, 10 Jan 1998 18:06:06 GMT",
"version": "v1"
},
{
"created": "Tue, 8 Sep 1998 12:10:31 GMT",
"version": "v2"
}
] | 2016-08-31 | [
[
"Gergely",
"László Á.",
"",
"KFKI RMKI, Budapest"
],
[
"Perjés",
"Zoltán I.",
"",
"KFKI RMKI, Budapest"
],
[
"Vasúth",
"Mátyás",
"",
"KFKI RMKI, Budapest"
]
] | A convenient formalism for averaging the losses produced by gravitational radiation backreaction over one orbital period was developed in an earlier paper. In the present paper we generalize this formalism to include the case of a closed system composed from two bodies of comparable masses, one of them having the spin S. We employ the equations of motion given by Barker and O'Connell, where terms up to linear order in the spin (the spin-orbit interaction terms) are kept. To obtain the radiative losses up to terms linear in the spin, the equations of motion are taken to the same order. Then the magnitude L of the angular momentum L, the angle kappa subtended by S and L and the energy E are conserved. The analysis of the radial motion leads to a new parametrization of the orbit. From the instantaneous gravitational radiation losses computed by Kidder the leading terms and the spin-orbit terms are taken. Following Apostolatos, Cutler, Sussman and Thorne, the evolution of the vectors S and L in the momentary plane spanned by these vectors is separated from the evolution of the plane in space. The radiation-induced change in the spin is smaller than the leading-order spin terms in the momentary angular momentum loss. This enables us to compute the averaged losses in the constants of motion E, L and L_S=L cos kappa. In the latter, the radiative spin loss terms average to zero. An alternative description using the orbital elements a,e and kappa is given. The finite mass effects contribute terms, comparable in magnitude, to the basic, test-particle spin terms in the averaged losses. |
gr-qc/9606037 | Patrick Peter | Jean-Philippe Uzan and Patrick Peter (DARC - Observatoire de Meudon,
France) | The no-defect conjecture in cosmic crystallography | LaTeX-REVTeX, 5 pages and 2 figures uuencoded, submitted to Phys.
Rev. Lett | Phys.Lett. B406 (1997) 20-25 | 10.1016/S0370-2693(97)00686-2 | null | gr-qc | null | The topology of space is usually assumed simply connected, but could be
multi-connected. We review in the latter case the possibility that topological
defects arising at high energy phase transitions might still be present and
find that either they are very unlikely to form at all, or space is effectively
simply connected on scales up to the horizon size.
| [
{
"created": "Sat, 15 Jun 1996 01:41:51 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Uzan",
"Jean-Philippe",
"",
"DARC - Observatoire de Meudon,\n France"
],
[
"Peter",
"Patrick",
"",
"DARC - Observatoire de Meudon,\n France"
]
] | The topology of space is usually assumed simply connected, but could be multi-connected. We review in the latter case the possibility that topological defects arising at high energy phase transitions might still be present and find that either they are very unlikely to form at all, or space is effectively simply connected on scales up to the horizon size. |
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