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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
2010.14059 | Mu-Tao Wang | Mu-Tao Wang | Limits of quasi-local angular momentum on an isolated gravitating system | Conference on Differential Geometry, Calabi-Yau Theory, and General
Relativity in celebration of the 70th Birthday of Shing-Tung Yau. arXiv admin
note: text overlap with arXiv:2003.07732 | null | null | null | gr-qc math-ph math.AP math.DG math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | I shall discuss the Chen-Wang-Yau quasilocal angular momentum, which is
defined based on the theory of optimal isometric embedding and quasilocal mass
of Wang-Yau, and the limits of which at spatial and null infinity of an
isolated gravitating system. This is based on joint work with Po-Ning Chen,
Jordan Keller, Ye-Kai Wang, and Shing-Tung Yau.
| [
{
"created": "Fri, 23 Oct 2020 21:39:08 GMT",
"version": "v1"
}
] | 2020-10-28 | [
[
"Wang",
"Mu-Tao",
""
]
] | I shall discuss the Chen-Wang-Yau quasilocal angular momentum, which is defined based on the theory of optimal isometric embedding and quasilocal mass of Wang-Yau, and the limits of which at spatial and null infinity of an isolated gravitating system. This is based on joint work with Po-Ning Chen, Jordan Keller, Ye-Kai Wang, and Shing-Tung Yau. |
2206.04964 | Alfredo Bautista | A. Bautista, A. Ibort, J. Lafuente | The space of light rays: Causality and $L$-boundary | 57 pages, 15 figures, accepted for publication in the topical
collection of General Relativity and Gravitation dedicated to the meeting
Singularity theorems, causality, and all that (SCRI21) in honor of Roger
Penrose | null | 10.1007/s10714-022-02942-3 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The space of light rays $\mathcal{N}$ of a conformal Lorentz manifold
$(M,\mathcal{C})$ is, under some topological conditions, a manifold whose basic
elements are unparametrized null geodesics. This manifold $\mathcal{N}$,
strongly inspired on R. Penrose's twistor theory, keeps all information of $M$
and it could be used as a space complementing the spacetime model. In the
present review, the geometry and related structures of $\mathcal{N}$, such as
the space of skies $\Sigma$ and the contact structure $\mathcal{H}$, are
introduced. The causal structure of $M$ is characterized as part of the
geometry of $\mathcal{N}$. A new causal boundary for spacetimes $M$ prompted by
R. Low, the $L$-boundary, is constructed in the case of $3$-dimensional
manifolds $M$ and proposed as a model of its construction for general
dimension. Its definition only depends on the geometry of $\mathcal{N}$ and not
on the geometry of the spacetime $M$. The properties satisfied by the
$L$-boundary $\partial M$ permit to characterize the obtained extension
$\overline{M}=M\cup \partial M$ and this characterization is also proposed for
general dimension.
| [
{
"created": "Fri, 10 Jun 2022 09:36:06 GMT",
"version": "v1"
}
] | 2022-06-29 | [
[
"Bautista",
"A.",
""
],
[
"Ibort",
"A.",
""
],
[
"Lafuente",
"J.",
""
]
] | The space of light rays $\mathcal{N}$ of a conformal Lorentz manifold $(M,\mathcal{C})$ is, under some topological conditions, a manifold whose basic elements are unparametrized null geodesics. This manifold $\mathcal{N}$, strongly inspired on R. Penrose's twistor theory, keeps all information of $M$ and it could be used as a space complementing the spacetime model. In the present review, the geometry and related structures of $\mathcal{N}$, such as the space of skies $\Sigma$ and the contact structure $\mathcal{H}$, are introduced. The causal structure of $M$ is characterized as part of the geometry of $\mathcal{N}$. A new causal boundary for spacetimes $M$ prompted by R. Low, the $L$-boundary, is constructed in the case of $3$-dimensional manifolds $M$ and proposed as a model of its construction for general dimension. Its definition only depends on the geometry of $\mathcal{N}$ and not on the geometry of the spacetime $M$. The properties satisfied by the $L$-boundary $\partial M$ permit to characterize the obtained extension $\overline{M}=M\cup \partial M$ and this characterization is also proposed for general dimension. |
gr-qc/9609055 | Bijan Saha | B. Saha and G. N. Shikin | Nonlinear Spinor Field in Bianchi type-I Universe filled with Perfect
Fluid: Exact Self-consistent Solutions | LaTex, 15 pages. Submitted to the Journal of Mathematical Physics | J.Math.Phys. 38 (1997) 5305-5318 | 10.1063/1.531944 | null | gr-qc | null | Self-consistent solutions to nonlinear spinor field equations in General
Relativity have been studied for the case of Bianchi type-I space-time filled
with perfect fluid. The initial and the asymptotic behavior of the field
functions and the metric one has been thoroughly studied. It should be
emphasized the absence of initial singularity for some types of solutions and
also the isotropic mode of space-time expansion in some special cases.
| [
{
"created": "Tue, 24 Sep 1996 14:06:12 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Saha",
"B.",
""
],
[
"Shikin",
"G. N.",
""
]
] | Self-consistent solutions to nonlinear spinor field equations in General Relativity have been studied for the case of Bianchi type-I space-time filled with perfect fluid. The initial and the asymptotic behavior of the field functions and the metric one has been thoroughly studied. It should be emphasized the absence of initial singularity for some types of solutions and also the isotropic mode of space-time expansion in some special cases. |
1005.2996 | Piero Nicolini | Piero Nicolini | Entropic force, noncommutative gravity and ungravity | 8 pages, final version published on Physical Review D | Phys.Rev.D82:044030,2010 | 10.1103/PhysRevD.82.044030 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | After recalling the basic concepts of gravity as an emergent phenomenon, we
analyze the recent derivation of Newton's law in terms of entropic force
proposed by Verlinde. By reviewing some points of the procedure, we extend it
to the case of a generic quantum gravity entropic correction to get compelling
deviations to the Newton's law. More specifically, we study: (1) noncommutative
geometry deviations and (2) ungraviton corrections. As a special result in the
noncommutative case, we find that the noncommutative character of the manifold
would be equivalent to the temperature of a thermodynamic system. Therefore, in
analogy to the zero temperature configuration, the description of spacetime in
terms of a differential manifold could be obtained only asymptotically.
Finally, we extend the Verlinde's derivation to a general case, which includes
all possible effects, noncommutativity, ungravity, asymptotically safe gravity,
electrostatic energy, and extra dimensions, showing that the procedure is solid
versus such modifications.
| [
{
"created": "Mon, 17 May 2010 19:00:14 GMT",
"version": "v1"
},
{
"created": "Sun, 13 Jun 2010 11:11:36 GMT",
"version": "v2"
},
{
"created": "Fri, 13 Aug 2010 16:34:19 GMT",
"version": "v3"
}
] | 2014-11-21 | [
[
"Nicolini",
"Piero",
""
]
] | After recalling the basic concepts of gravity as an emergent phenomenon, we analyze the recent derivation of Newton's law in terms of entropic force proposed by Verlinde. By reviewing some points of the procedure, we extend it to the case of a generic quantum gravity entropic correction to get compelling deviations to the Newton's law. More specifically, we study: (1) noncommutative geometry deviations and (2) ungraviton corrections. As a special result in the noncommutative case, we find that the noncommutative character of the manifold would be equivalent to the temperature of a thermodynamic system. Therefore, in analogy to the zero temperature configuration, the description of spacetime in terms of a differential manifold could be obtained only asymptotically. Finally, we extend the Verlinde's derivation to a general case, which includes all possible effects, noncommutativity, ungravity, asymptotically safe gravity, electrostatic energy, and extra dimensions, showing that the procedure is solid versus such modifications. |
gr-qc/0307052 | Rainer Dick | Rainer Dick | On the Newtonian Limit in Gravity Models with Inverse Powers of R | 8 pages | Gen.Rel.Grav. 36 (2004) 217-224 | 10.1023/B:GERG.0000006968.53367.59 | null | gr-qc astro-ph | null | I reconsider the problem of the Newtonian limit in nonlinear gravity models
in the light of recently proposed models with inverse powers of the Ricci
scalar.
Expansion around a maximally symmetric local background with positive
curvature scalar R_0 gives the correct Newtonian limit on length scales <<
R_0^{-1/2} if the gravitational Lagrangian f(R) satisfies |f(R_0)f''(R_0)|<< 1.
I propose two models with f''(R_0)=0.
| [
{
"created": "Thu, 10 Jul 2003 16:07:10 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Dick",
"Rainer",
""
]
] | I reconsider the problem of the Newtonian limit in nonlinear gravity models in the light of recently proposed models with inverse powers of the Ricci scalar. Expansion around a maximally symmetric local background with positive curvature scalar R_0 gives the correct Newtonian limit on length scales << R_0^{-1/2} if the gravitational Lagrangian f(R) satisfies |f(R_0)f''(R_0)|<< 1. I propose two models with f''(R_0)=0. |
2303.04107 | Burkhard Kleihaus | Burkhard Kleihaus, Jutta Kunz, Tim Uterm\"ohlen, Emanuele Berti | Quadrupole instability of static scalarized black holes | 5 pages, 4 figures | null | 10.1103/PhysRevD.107.L081501 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The addition of a Ricci coupling to Einstein-scalar-Gauss-Bonnet theories
makes general relativity a cosmological attractor. Previous work considered a
quadratic coupling function with two independent coupling constants in such
theories and showed that static, spherically symmetric, spontaneously
scalarized black holes are radially stable beyond a critical value of the Ricci
coupling constant. Here we demonstrate that these black holes are affected by a
quadrupole instability which leads to two new branches of static, axially
symmetric scalarized black holes. We discuss the properties of these solutions
and provide embedding diagrams.
| [
{
"created": "Tue, 7 Mar 2023 18:17:24 GMT",
"version": "v1"
}
] | 2023-05-10 | [
[
"Kleihaus",
"Burkhard",
""
],
[
"Kunz",
"Jutta",
""
],
[
"Utermöhlen",
"Tim",
""
],
[
"Berti",
"Emanuele",
""
]
] | The addition of a Ricci coupling to Einstein-scalar-Gauss-Bonnet theories makes general relativity a cosmological attractor. Previous work considered a quadratic coupling function with two independent coupling constants in such theories and showed that static, spherically symmetric, spontaneously scalarized black holes are radially stable beyond a critical value of the Ricci coupling constant. Here we demonstrate that these black holes are affected by a quadrupole instability which leads to two new branches of static, axially symmetric scalarized black holes. We discuss the properties of these solutions and provide embedding diagrams. |
gr-qc/0312030 | Mark A. Miller | Mark Miller, Philip Gressman, and Wai-Mo Suen | Towards a Realistic Neutron Star Binary Inspiral: Initial Data and
Multiple Orbit Evolution in Full General Relativity | 22 pages, 18 figures, accepted to Phys. Rev. D | Phys.Rev. D69 (2004) 064026 | 10.1103/PhysRevD.69.064026 | null | gr-qc astro-ph | null | This paper reports on our effort in modeling realistic astrophysical neutron
star binaries in general relativity. We analyze under what conditions the
conformally flat quasiequilibrium (CFQE) approach can generate
``astrophysically relevant'' initial data, by developing an analysis that
determines the violation of the CFQE approximation in the evolution of the
binary described by the full Einstein theory. We show that the CFQE assumptions
significantly violate the Einstein field equations for corotating neutron stars
at orbital separations nearly double that of the innermost stable circular
orbit (ISCO) separation, thus calling into question the astrophysical relevance
of the ISCO determined in the CFQE approach. With the need to start numerical
simulations at large orbital separation in mind, we push for stable and long
term integrations of the full Einstein equations for the binary neutron star
system. We demonstrate the stability of our numerical treatment and analyze the
stringent requirements on resolution and size of the computational domain for
an accurate simulation of the system.
| [
{
"created": "Thu, 4 Dec 2003 16:59:26 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Miller",
"Mark",
""
],
[
"Gressman",
"Philip",
""
],
[
"Suen",
"Wai-Mo",
""
]
] | This paper reports on our effort in modeling realistic astrophysical neutron star binaries in general relativity. We analyze under what conditions the conformally flat quasiequilibrium (CFQE) approach can generate ``astrophysically relevant'' initial data, by developing an analysis that determines the violation of the CFQE approximation in the evolution of the binary described by the full Einstein theory. We show that the CFQE assumptions significantly violate the Einstein field equations for corotating neutron stars at orbital separations nearly double that of the innermost stable circular orbit (ISCO) separation, thus calling into question the astrophysical relevance of the ISCO determined in the CFQE approach. With the need to start numerical simulations at large orbital separation in mind, we push for stable and long term integrations of the full Einstein equations for the binary neutron star system. We demonstrate the stability of our numerical treatment and analyze the stringent requirements on resolution and size of the computational domain for an accurate simulation of the system. |
2303.05810 | Enderson Falc\'on | Enderson Falc\'on-Gomez, Vittorio De Falco, Kerlos Atia Abdalmalak,
Adri\'an Amor-Mart\'in, Valent\'in De La Rubia, Gabriel Santamar\'ia-Botello,
Luis Enrique Garc\'ia Mu\~noz | Interaction between linear polarized plane gravitational waves and a
plane electromagnetic wave in the electromagnetic-gravity analogue | 10 pages, 4 figures, 2 tables. Accepted for publication on Physical
Review D | null | 10.1103/PhysRevD.107.124042 | null | gr-qc astro-ph.HE hep-th | http://creativecommons.org/licenses/by/4.0/ | We study the interaction among gravitational and electromagnetic plane waves
by means of an analogue electromagnetic model of gravity, where the
gravitational properties are encoded in the electromagnetic properties of a
material in flat space-time. In this setup, the variations in the metric tensor
produced by the gravitational waves are codified as space-time-varying
electromagnetic properties. We used an in-housed code based in the
finite-difference time domain method to conduct numerical experiments, where we
found that, when a monochromatic gravitational plane wave interacts with a
narrow-band electromagnetic plane wave, an infinite number of sidebands,
equally separated between themselves, are induced by the gravitational wave.
Finally, we discuss possible future applications of this effect as an
alternative method to directly detect gravitational waves.
| [
{
"created": "Fri, 10 Mar 2023 09:32:01 GMT",
"version": "v1"
}
] | 2023-07-05 | [
[
"Falcón-Gomez",
"Enderson",
""
],
[
"De Falco",
"Vittorio",
""
],
[
"Abdalmalak",
"Kerlos Atia",
""
],
[
"Amor-Martín",
"Adrián",
""
],
[
"De La Rubia",
"Valentín",
""
],
[
"Santamaría-Botello",
"Gabriel",
""
],
[
"Muñoz",
"Luis Enrique García",
""
]
] | We study the interaction among gravitational and electromagnetic plane waves by means of an analogue electromagnetic model of gravity, where the gravitational properties are encoded in the electromagnetic properties of a material in flat space-time. In this setup, the variations in the metric tensor produced by the gravitational waves are codified as space-time-varying electromagnetic properties. We used an in-housed code based in the finite-difference time domain method to conduct numerical experiments, where we found that, when a monochromatic gravitational plane wave interacts with a narrow-band electromagnetic plane wave, an infinite number of sidebands, equally separated between themselves, are induced by the gravitational wave. Finally, we discuss possible future applications of this effect as an alternative method to directly detect gravitational waves. |
2004.11334 | Carl-Johan Haster | Carl-Johan Haster, Katerina Chatziioannou, Andreas Bauswein, James
Alexander Clark | Inference of the neutron star equation of state from cosmological
distances | 8 pages, 4 figures | Phys. Rev. Lett. 125, 261101 (2020) | 10.1103/PhysRevLett.125.261101 | LIGO-P2000143 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Finite-size effects on the gravitational wave signal from a neutron star
merger typically manifest at high frequencies where detector sensitivity
decreases. Proposed sensitivity improvements can give us access both to
stronger signals and to a myriad of weak signals from cosmological distances.
The latter will outnumber the former and the relevant part of signal will be
redshifted towards the detector most sensitive band. We study the redshift
dependence of information about neutron star matter and find that single-scale
properties, such as the star radius or the post-merger frequency, are better
measured from the distant weak sources from $z\sim 1$.
| [
{
"created": "Thu, 23 Apr 2020 17:29:39 GMT",
"version": "v1"
}
] | 2021-01-04 | [
[
"Haster",
"Carl-Johan",
""
],
[
"Chatziioannou",
"Katerina",
""
],
[
"Bauswein",
"Andreas",
""
],
[
"Clark",
"James Alexander",
""
]
] | Finite-size effects on the gravitational wave signal from a neutron star merger typically manifest at high frequencies where detector sensitivity decreases. Proposed sensitivity improvements can give us access both to stronger signals and to a myriad of weak signals from cosmological distances. The latter will outnumber the former and the relevant part of signal will be redshifted towards the detector most sensitive band. We study the redshift dependence of information about neutron star matter and find that single-scale properties, such as the star radius or the post-merger frequency, are better measured from the distant weak sources from $z\sim 1$. |
0709.3866 | Michael Martin Nieto | Michael Martin Nieto and John D. Anderson | Search for a Solution of the Pioneer Anomaly | 24 pages 8 figures | Contemp.Phys.48:41-54,2007 | 10.1080/00107510701462061 | LA-UR-07-2169 | gr-qc | null | In 1972 and 1973 the Pioneer 10 and 11 missions were launched. They were the
first to explore the outer solar system and achieved stunning breakthroughs in
deep-space exploration. But beginning in about 1980 an unmodeled force of \sim
8 \times 10^{-8} cm/s^2, directed approximately towards the Sun, appeared in
the tracking data. It later was unambiguously verified as being in the data and
not an artifact. The cause remains unknown (although radiant heat remains a
likely origin). With time more and more effort has gone into understanding this
anomaly (and also possibly related effects). We review the situation and
describe ongoing programs to resolve the issue.
| [
{
"created": "Tue, 25 Sep 2007 02:14:36 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Nieto",
"Michael Martin",
""
],
[
"Anderson",
"John D.",
""
]
] | In 1972 and 1973 the Pioneer 10 and 11 missions were launched. They were the first to explore the outer solar system and achieved stunning breakthroughs in deep-space exploration. But beginning in about 1980 an unmodeled force of \sim 8 \times 10^{-8} cm/s^2, directed approximately towards the Sun, appeared in the tracking data. It later was unambiguously verified as being in the data and not an artifact. The cause remains unknown (although radiant heat remains a likely origin). With time more and more effort has gone into understanding this anomaly (and also possibly related effects). We review the situation and describe ongoing programs to resolve the issue. |
1008.3841 | Alfonso Garc\'ia-Parrado G\'omez-Lobo Dr. | Alfonso Garc\'ia-Parrado G\'omez-Lobo | A note on time-symmetric hypersurfaces in the Schwarzschild geometry | Proof of corollary 2 extended to include hypersurfaces with null
regions. Some additional considerations in section 4 dealing with
hypersurfaces of arbitrary causal character added. References added, To
appear in classical and quantum gravity | Class.Quant.Grav.27:217001,2010 | 10.1088/0264-9381/27/21/217001 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this note we show that any inextensible time-symmetric space-like
hypersurface of differentiability class $C^k$, $k\geq 2$ isometrically embedded
in the maximal Schwarzschild geometry must intersect the bifurcation sphere.
| [
{
"created": "Mon, 23 Aug 2010 15:56:31 GMT",
"version": "v1"
},
{
"created": "Wed, 22 Sep 2010 16:29:30 GMT",
"version": "v2"
}
] | 2010-11-13 | [
[
"Gómez-Lobo",
"Alfonso García-Parrado",
""
]
] | In this note we show that any inextensible time-symmetric space-like hypersurface of differentiability class $C^k$, $k\geq 2$ isometrically embedded in the maximal Schwarzschild geometry must intersect the bifurcation sphere. |
1905.07981 | Takafumi Kokubu | Takafumi Kokubu and Tomohiro Harada | Burst particle creation in gravitational collapse to a horizonless
compact object | 30 pages, 12 figures | Phys. Rev. D 100, 084028 (2019) | 10.1103/PhysRevD.100.084028 | RUP-19-14 | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the previous paper [Harada, Cardoso, and Miyata, Phys.\ Rev.\ D {\bf 99}
(2019), 044039], it is shown that a hollow transmissive shell collapsing to an
ultracompact object of radius very close to its horizon radius generally emits
transient Hawking radiation followed by a couple of bursts separated each other
by a long time interval. In the current paper, we expand the previous work in
two independent directions: changing boundary conditions and specifying the
equations of state of the matter. First, we introduce a perfectly reflective
surface collapsing to an ultracompact object and find that this model also
emits transient Hawking radiation that is followed only by a single burst.
Second, we introduce two different collapse dynamics to an ultracompact object
and specify the corresponding matter equations of state. We find that transient
Hawking radiation is quite commonly seen in early times, while the subsequent
bursts strongly depend on the boundary condition and the equation of state or
the braking behavior of the surface.
| [
{
"created": "Mon, 20 May 2019 10:39:57 GMT",
"version": "v1"
},
{
"created": "Tue, 28 May 2019 00:28:11 GMT",
"version": "v2"
}
] | 2019-10-23 | [
[
"Kokubu",
"Takafumi",
""
],
[
"Harada",
"Tomohiro",
""
]
] | In the previous paper [Harada, Cardoso, and Miyata, Phys.\ Rev.\ D {\bf 99} (2019), 044039], it is shown that a hollow transmissive shell collapsing to an ultracompact object of radius very close to its horizon radius generally emits transient Hawking radiation followed by a couple of bursts separated each other by a long time interval. In the current paper, we expand the previous work in two independent directions: changing boundary conditions and specifying the equations of state of the matter. First, we introduce a perfectly reflective surface collapsing to an ultracompact object and find that this model also emits transient Hawking radiation that is followed only by a single burst. Second, we introduce two different collapse dynamics to an ultracompact object and specify the corresponding matter equations of state. We find that transient Hawking radiation is quite commonly seen in early times, while the subsequent bursts strongly depend on the boundary condition and the equation of state or the braking behavior of the surface. |
1911.02693 | Feroz Shaik | Feroz H. Shaik, Jacob Lange, Scott E. Field, Richard O'Shaughnessy,
Vijay Varma, Lawrence E. Kidder, Harald P. Pfeiffer, and Daniel Wysocki | Impact of subdominant modes on the interpretation of gravitational-wave
signals from heavy binary black hole systems | 24 pages, 12 figures, 1 table; version 2 contains additional material
including a comparison to previous works and measuring individual black hole
spins | Phys. Rev. D 101, 124054 (2020) | 10.1103/PhysRevD.101.124054 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Over the past year, a handful of new gravitational wave models have been
developed to include multiple harmonic modes thereby enabling for the first
time fully Bayesian inference studies including higher modes to be performed.
Using one recently-developed numerical relativity surrogate model,
NRHybSur3dq8, we investigate the importance of higher modes on parameter
inference of coalescing massive binary black holes. We focus on examples
relevant to the current three-detector network of observatories, with a
detector-frame mass set to $120 M_\odot$ and with signal amplitude values that
are consistent with plausible candidates for the next few observing runs. We
show that for such systems the higher mode content will be important for
interpreting coalescing binary black holes, reducing systematic bias, and
computing properties of the remnant object. Even for comparable-mass binaries
and at low signal amplitude, the omission of higher modes can influence
posterior probability distributions. We discuss the impact of our results on
source population inference and self-consistency tests of general relativity.
Our work can be used to better understand asymmetric binary black hole merger
events, such as GW190412. Higher modes are critical for such systems, and their
omission usually produces substantial parameter biases.
| [
{
"created": "Thu, 7 Nov 2019 00:56:05 GMT",
"version": "v1"
},
{
"created": "Tue, 23 Jun 2020 19:33:22 GMT",
"version": "v2"
}
] | 2020-07-01 | [
[
"Shaik",
"Feroz H.",
""
],
[
"Lange",
"Jacob",
""
],
[
"Field",
"Scott E.",
""
],
[
"O'Shaughnessy",
"Richard",
""
],
[
"Varma",
"Vijay",
""
],
[
"Kidder",
"Lawrence E.",
""
],
[
"Pfeiffer",
"Harald P.",
""
],
[
"Wysocki",
"Daniel",
""
]
] | Over the past year, a handful of new gravitational wave models have been developed to include multiple harmonic modes thereby enabling for the first time fully Bayesian inference studies including higher modes to be performed. Using one recently-developed numerical relativity surrogate model, NRHybSur3dq8, we investigate the importance of higher modes on parameter inference of coalescing massive binary black holes. We focus on examples relevant to the current three-detector network of observatories, with a detector-frame mass set to $120 M_\odot$ and with signal amplitude values that are consistent with plausible candidates for the next few observing runs. We show that for such systems the higher mode content will be important for interpreting coalescing binary black holes, reducing systematic bias, and computing properties of the remnant object. Even for comparable-mass binaries and at low signal amplitude, the omission of higher modes can influence posterior probability distributions. We discuss the impact of our results on source population inference and self-consistency tests of general relativity. Our work can be used to better understand asymmetric binary black hole merger events, such as GW190412. Higher modes are critical for such systems, and their omission usually produces substantial parameter biases. |
2006.11289 | Saeed Ullah Khan | Saeed Ullah Khan and Jingli Ren | Shadow cast by a rotating charged black hole in quintessential dark
energy | 11 Pages, 7 figures, Matches published version | Phys. Dark Universe (2020) | 10.1016/j.dark.2020.100644 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The existence of quintessential dark energy around a black hole has
considerable consequences on its spacetime geometry. Hence, in this article, we
explore its effect on horizons and the silhouette generated by a Kerr-Newman
black hole in quintessential dark energy. Moreover, to analyze the deflection
angle of light, we utilize the Gauss-Bonnet theorem. The obtained result
demonstrates that, due to the dragging effect, the black hole spin elongates
its shadow in the direction of the rotational axis, while increases the
deflection angle. On the other hand, the black hole charge diminishing its
shadow, as well as the angle of lights deflection. Besides, both spin and
charge significantly increase the distortion effect in the black hole's shadow.
The quintessence parameter \gamma, increases the shadow radius, while decreases
the distortion effect at higher values of charge and spin parameters.
| [
{
"created": "Sat, 20 Jun 2020 16:05:50 GMT",
"version": "v1"
}
] | 2020-06-23 | [
[
"Khan",
"Saeed Ullah",
""
],
[
"Ren",
"Jingli",
""
]
] | The existence of quintessential dark energy around a black hole has considerable consequences on its spacetime geometry. Hence, in this article, we explore its effect on horizons and the silhouette generated by a Kerr-Newman black hole in quintessential dark energy. Moreover, to analyze the deflection angle of light, we utilize the Gauss-Bonnet theorem. The obtained result demonstrates that, due to the dragging effect, the black hole spin elongates its shadow in the direction of the rotational axis, while increases the deflection angle. On the other hand, the black hole charge diminishing its shadow, as well as the angle of lights deflection. Besides, both spin and charge significantly increase the distortion effect in the black hole's shadow. The quintessence parameter \gamma, increases the shadow radius, while decreases the distortion effect at higher values of charge and spin parameters. |
2310.17339 | D\'ebora Aguiar Gomes | D\'ebora Aguiar Gomes, Rebecca Briffa, Aleksander Kozak, Jackson Levi
Said, Margus Saal and Aneta Wojnar | Cosmological constraints of Palatini $f(\mathcal{R})$ gravity | 19 pages, 3 figures | JCAP01(2024)011 | 10.1088/1475-7516/2024/01/011 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this study, we investigate a Palatini $f(R)$ gravity model featuring a
quadratic term correction, aligning it with the most recent expansion rate
data, with a particular focus on the latest SNIa and BAO data. Our analysis
employs CC data as the fundamental dataset, complemented by contributions from
the SN sample and a combination of non-overlapping transversal BAO datasets. We
conduct a comprehensive MCMC analysis for each data set combination, yielding
constraints on all cosmological parameters within the model. Additionally, we
incorporate the latest Hubble constant value from the SH0ES Team. Finally, we
present a statistical comparison between the Palatini quadratic model and
$\Lambda$CDM using the AIC and BIC metrics, ultimately obtaining the constraint
$|\alpha| \leq 10^{49}\,\text{m}^2$. We also stress the significance of
studying stellar and substellar objects for obtaining more precise constraints
on modified gravity compared to those derived from cosmological observations.
| [
{
"created": "Thu, 26 Oct 2023 12:10:21 GMT",
"version": "v1"
}
] | 2024-01-10 | [
[
"Gomes",
"Débora Aguiar",
""
],
[
"Briffa",
"Rebecca",
""
],
[
"Kozak",
"Aleksander",
""
],
[
"Said",
"Jackson Levi",
""
],
[
"Saal",
"Margus",
""
],
[
"Wojnar",
"Aneta",
""
]
] | In this study, we investigate a Palatini $f(R)$ gravity model featuring a quadratic term correction, aligning it with the most recent expansion rate data, with a particular focus on the latest SNIa and BAO data. Our analysis employs CC data as the fundamental dataset, complemented by contributions from the SN sample and a combination of non-overlapping transversal BAO datasets. We conduct a comprehensive MCMC analysis for each data set combination, yielding constraints on all cosmological parameters within the model. Additionally, we incorporate the latest Hubble constant value from the SH0ES Team. Finally, we present a statistical comparison between the Palatini quadratic model and $\Lambda$CDM using the AIC and BIC metrics, ultimately obtaining the constraint $|\alpha| \leq 10^{49}\,\text{m}^2$. We also stress the significance of studying stellar and substellar objects for obtaining more precise constraints on modified gravity compared to those derived from cosmological observations. |
1402.0657 | Peter Horvathy | C. Duval, G. W. Gibbons, P. A. Horvathy, P. M. Zhang | Carroll versus Newton and Galilei: two dual non-Einsteinian concepts of
time | 32 pages, no figures. A minor error corrected. Accepted for
publication in Classical and Quantum Gravity | null | 10.1088/0264-9381/31/8/085016 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Carroll group was originally introduced by Levy-Leblond [1] by
considering the limit of the Poincar\'e group as $c\to0$. In this paper an
alternative definition, based on the geometric properties of a non-Minkowskian,
non-Galilean but nevertheless boost-invariant, space-time structure is
proposed. A "duality" with the Galilean limit $c\to\infty$ is established. Our
theory is illustrated by Carrollian electromagnetism.
| [
{
"created": "Tue, 4 Feb 2014 08:43:18 GMT",
"version": "v1"
},
{
"created": "Fri, 7 Feb 2014 09:26:12 GMT",
"version": "v2"
},
{
"created": "Tue, 25 Feb 2014 02:51:20 GMT",
"version": "v3"
},
{
"created": "Wed, 26 Feb 2014 01:33:22 GMT",
"version": "v4"
},
{
"created": "Tue, 11 Mar 2014 02:02:22 GMT",
"version": "v5"
}
] | 2015-06-18 | [
[
"Duval",
"C.",
""
],
[
"Gibbons",
"G. W.",
""
],
[
"Horvathy",
"P. A.",
""
],
[
"Zhang",
"P. M.",
""
]
] | The Carroll group was originally introduced by Levy-Leblond [1] by considering the limit of the Poincar\'e group as $c\to0$. In this paper an alternative definition, based on the geometric properties of a non-Minkowskian, non-Galilean but nevertheless boost-invariant, space-time structure is proposed. A "duality" with the Galilean limit $c\to\infty$ is established. Our theory is illustrated by Carrollian electromagnetism. |
1307.2552 | Lijing Shao | Lijing Shao, R. Nicolas Caballero, Michael Kramer, Norbert Wex, David
J. Champion, Axel Jessner | A new limit on local Lorentz invariance violation of gravity from
solitary pulsars | 25 pages, 9 figures; accepted by Classical and Quantum Gravity | Class. Quantum Grav. 30 (2013) 165019 | 10.1088/0264-9381/30/16/165019 | null | gr-qc astro-ph.CO astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational preferred frame effects are generally predicted by alternative
theories that exhibit an isotropic violation of local Lorentz invariance of
gravity. They are described by three parameters in the parametrized
post-Newtonian formalism. One of their strong-field generalizations, $\hat
\alpha_2$, induces a precession of a pulsar's spin around its movement
direction with respect to the preferred frame. We constrain $\hat \alpha_2$ by
using the non-detection of such a precession using the characteristics of the
pulse profile. In our analysis we use a large number of observations from the
100-m Effelsberg radio telescope, which cover a time span of approximately 15
years. By combining data from two solitary millisecond pulsars, PSRs B1937+21
and J1744-1134, we get a limit of $|\hat \alpha_2| < 1.6 \times 10^{-9}$ at 95%
confidence level, which is more than two orders of magnitude better than its
best weak-field counterpart from the Solar system.
| [
{
"created": "Tue, 9 Jul 2013 19:29:41 GMT",
"version": "v1"
}
] | 2013-07-29 | [
[
"Shao",
"Lijing",
""
],
[
"Caballero",
"R. Nicolas",
""
],
[
"Kramer",
"Michael",
""
],
[
"Wex",
"Norbert",
""
],
[
"Champion",
"David J.",
""
],
[
"Jessner",
"Axel",
""
]
] | Gravitational preferred frame effects are generally predicted by alternative theories that exhibit an isotropic violation of local Lorentz invariance of gravity. They are described by three parameters in the parametrized post-Newtonian formalism. One of their strong-field generalizations, $\hat \alpha_2$, induces a precession of a pulsar's spin around its movement direction with respect to the preferred frame. We constrain $\hat \alpha_2$ by using the non-detection of such a precession using the characteristics of the pulse profile. In our analysis we use a large number of observations from the 100-m Effelsberg radio telescope, which cover a time span of approximately 15 years. By combining data from two solitary millisecond pulsars, PSRs B1937+21 and J1744-1134, we get a limit of $|\hat \alpha_2| < 1.6 \times 10^{-9}$ at 95% confidence level, which is more than two orders of magnitude better than its best weak-field counterpart from the Solar system. |
1604.02448 | Mehdi Saravani | Mehdi Saravani and Niayesh Afshordi | Off-shell Dark Matter: A Cosmological relic of Quantum Gravity | null | Phys. Rev. D 95, 043514 (2017) | 10.1103/PhysRevD.95.043514 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study a novel proposal for the origin of cosmological cold dark matter
(CDM) which is rooted in the quantum nature of spacetime. In this model,
off-shell modes of quantum fields can exist in asymptotic states as a result of
spacetime nonlocality (expected in generic theories of quantum gravity), and
play the role of CDM, which we dub off-shell dark matter (OfDM). However, their
rate of production is suppressed by the scale of non-locality (e.g. Planck
length). As a result, we show that OfDM is only produced in the first moments
of big bang, and then effectively decouples (except through its gravitational
interactions). We examine the observational predictions of this model: In the
context of cosmic inflation, we show that this proposal relates the reheating
temperature to the inflaton mass, which narrows down the uncertainty in the
number of e-foldings of specific inflationary scenarios. We also demonstrate
that OfDM is indeed cold, and discuss potentially observable signatures on
small scale matter power spectrum.
| [
{
"created": "Fri, 8 Apr 2016 19:59:42 GMT",
"version": "v1"
}
] | 2017-02-22 | [
[
"Saravani",
"Mehdi",
""
],
[
"Afshordi",
"Niayesh",
""
]
] | We study a novel proposal for the origin of cosmological cold dark matter (CDM) which is rooted in the quantum nature of spacetime. In this model, off-shell modes of quantum fields can exist in asymptotic states as a result of spacetime nonlocality (expected in generic theories of quantum gravity), and play the role of CDM, which we dub off-shell dark matter (OfDM). However, their rate of production is suppressed by the scale of non-locality (e.g. Planck length). As a result, we show that OfDM is only produced in the first moments of big bang, and then effectively decouples (except through its gravitational interactions). We examine the observational predictions of this model: In the context of cosmic inflation, we show that this proposal relates the reheating temperature to the inflaton mass, which narrows down the uncertainty in the number of e-foldings of specific inflationary scenarios. We also demonstrate that OfDM is indeed cold, and discuss potentially observable signatures on small scale matter power spectrum. |
1905.06615 | Oleg Tsupko | Gennady S. Bisnovatyi-Kogan and Oleg Yu. Tsupko | Gravitational Lensing in presence of Plasma: Strong Lens Systems, Black
Hole Lensing and Shadow | Invited Review for Special Issue "Gravitational Lensing and
Astrometry" of Universe (published in 2017); partially based on our previous
papers arXiv:0809.1021, arXiv:1006.2321, arXiv:1305.7032, arXiv:1505.06481,
arXiv:1507.04217, arXiv:1702.08768; see also other review arXiv:1507.08545 | Universe 2017, 3, 57 | 10.3390/universe3030057 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this article, we present an overview of the new developments in problems
of the plasma influence on the effects of gravitational lensing, complemented
by pieces of new material and relevant discussions. Deflection of light in the
presence of gravity and plasma is determined by a complex combination of
various physical phenomena: gravity, dispersion, refraction. In particular, the
gravitational deflection itself, in a homogeneous plasma without refraction,
differs from the vacuum one and depends on the frequency of the photon. In an
inhomogeneous plasma, chromatic refraction also takes place. We describe
chromatic effects in strong lens systems including a shift of angular position
of image and a change in magnification. We also investigate high-order images
that arise when lensing on a black hole surrounded by homogeneous plasma. The
recent results of analytical studies of the effect of plasma on the shadow of
the Schwarzschild and Kerr black holes are presented.
| [
{
"created": "Thu, 16 May 2019 09:36:39 GMT",
"version": "v1"
}
] | 2019-05-17 | [
[
"Bisnovatyi-Kogan",
"Gennady S.",
""
],
[
"Tsupko",
"Oleg Yu.",
""
]
] | In this article, we present an overview of the new developments in problems of the plasma influence on the effects of gravitational lensing, complemented by pieces of new material and relevant discussions. Deflection of light in the presence of gravity and plasma is determined by a complex combination of various physical phenomena: gravity, dispersion, refraction. In particular, the gravitational deflection itself, in a homogeneous plasma without refraction, differs from the vacuum one and depends on the frequency of the photon. In an inhomogeneous plasma, chromatic refraction also takes place. We describe chromatic effects in strong lens systems including a shift of angular position of image and a change in magnification. We also investigate high-order images that arise when lensing on a black hole surrounded by homogeneous plasma. The recent results of analytical studies of the effect of plasma on the shadow of the Schwarzschild and Kerr black holes are presented. |
0712.4405 | Steven Detweiler | Ian Vega, Steven Detweiler | Regularization of fields for self-force problems in curved spacetime:
foundations and a time-domain application | 15 pages, 12 figures, 1 table. More figures, extended summary | Phys.Rev.D77:084008,2008 | 10.1103/PhysRevD.77.084008 | null | gr-qc | null | We propose an approach for the calculation of self-forces, energy fluxes and
waveforms arising from moving point charges in curved spacetimes. As opposed to
mode-sum schemes that regularize the self-force derived from the singular
retarded field, this approach regularizes the retarded field itself. The
singular part of the retarded field is first analytically identified and
removed, yielding a finite, differentiable remainder from which the self-force
is easily calculated. This regular remainder solves a wave equation which
enjoys the benefit of having a non-singular source. Solving this wave equation
for the remainder completely avoids the calculation of the singular retarded
field along with the attendant difficulties associated with numerically
modeling a delta function source. From this differentiable remainder one may
compute the self-force, the energy flux, and also a waveform which reflects the
effects of the self-force. As a test of principle, we implement this method
using a 4th-order (1+1) code, and calculate the self-force for the simple case
of a scalar charge moving in a circular orbit around a Schwarzschild black
hole. We achieve agreement with frequency-domain results to ~ 0.1% or better.
| [
{
"created": "Fri, 28 Dec 2007 20:59:22 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Jan 2008 14:51:35 GMT",
"version": "v2"
}
] | 2010-05-12 | [
[
"Vega",
"Ian",
""
],
[
"Detweiler",
"Steven",
""
]
] | We propose an approach for the calculation of self-forces, energy fluxes and waveforms arising from moving point charges in curved spacetimes. As opposed to mode-sum schemes that regularize the self-force derived from the singular retarded field, this approach regularizes the retarded field itself. The singular part of the retarded field is first analytically identified and removed, yielding a finite, differentiable remainder from which the self-force is easily calculated. This regular remainder solves a wave equation which enjoys the benefit of having a non-singular source. Solving this wave equation for the remainder completely avoids the calculation of the singular retarded field along with the attendant difficulties associated with numerically modeling a delta function source. From this differentiable remainder one may compute the self-force, the energy flux, and also a waveform which reflects the effects of the self-force. As a test of principle, we implement this method using a 4th-order (1+1) code, and calculate the self-force for the simple case of a scalar charge moving in a circular orbit around a Schwarzschild black hole. We achieve agreement with frequency-domain results to ~ 0.1% or better. |
0707.2982 | Michele Vallisneri | Curt Cutler and Michele Vallisneri | LISA detections of massive black hole inspirals: parameter extraction
errors due to inaccurate template waveforms | RevTeX4, 16 pages, 2 EPS figures. Corrected typos, clarified
statements | Phys.Rev.D76:104018,2007 | 10.1103/PhysRevD.76.104018 | null | gr-qc | null | The planned Laser Interferometer Space Antenna (LISA) is expected to detect
the inspiral and merger of massive black hole binaries (MBHBs) at z <~ 5 with
signal-to-noise ratios (SNRs) of hundreds to thousands. Because of these high
SNRs, and because these SNRs accrete over periods of weeks to months, it should
be possible to extract the physical parameters of these systems with high
accuracy; for instance, for a ~ 10^6 Msun MBHBs at z = 1 it should be possible
to determine the two masses to ~ 0.1% and the sky location to ~ 1 degree.
However, those are just the errors due to noise: there will be additional
"theoretical" errors due to inaccuracies in our best model waveforms, which are
still only approximate. The goal of this paper is to estimate the typical
magnitude of these theoretical errors. We develop mathematical tools for this
purpose, and apply them to a somewhat simplified version of the MBHB problem,
in which we consider just the inspiral part of the waveform and neglect
spin-induced precession, eccentricity, and PN amplitude corrections. For this
simplified version, we estimate that theoretical uncertainties in sky position
will typically be ~ 1 degree, i.e., comparable to the statistical uncertainty.
For the mass and spin parameters, our results suggest that while theoretical
errors will be rather small absolutely, they could still dominate over
statistical errors (by roughly an order of magnitude) for the strongest
sources. The tools developed here should be useful for estimating the magnitude
of theoretical errors in many other problems in gravitational-wave astronomy.
| [
{
"created": "Fri, 20 Jul 2007 00:37:23 GMT",
"version": "v1"
},
{
"created": "Wed, 5 Sep 2007 19:38:44 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Cutler",
"Curt",
""
],
[
"Vallisneri",
"Michele",
""
]
] | The planned Laser Interferometer Space Antenna (LISA) is expected to detect the inspiral and merger of massive black hole binaries (MBHBs) at z <~ 5 with signal-to-noise ratios (SNRs) of hundreds to thousands. Because of these high SNRs, and because these SNRs accrete over periods of weeks to months, it should be possible to extract the physical parameters of these systems with high accuracy; for instance, for a ~ 10^6 Msun MBHBs at z = 1 it should be possible to determine the two masses to ~ 0.1% and the sky location to ~ 1 degree. However, those are just the errors due to noise: there will be additional "theoretical" errors due to inaccuracies in our best model waveforms, which are still only approximate. The goal of this paper is to estimate the typical magnitude of these theoretical errors. We develop mathematical tools for this purpose, and apply them to a somewhat simplified version of the MBHB problem, in which we consider just the inspiral part of the waveform and neglect spin-induced precession, eccentricity, and PN amplitude corrections. For this simplified version, we estimate that theoretical uncertainties in sky position will typically be ~ 1 degree, i.e., comparable to the statistical uncertainty. For the mass and spin parameters, our results suggest that while theoretical errors will be rather small absolutely, they could still dominate over statistical errors (by roughly an order of magnitude) for the strongest sources. The tools developed here should be useful for estimating the magnitude of theoretical errors in many other problems in gravitational-wave astronomy. |
1907.05863 | D. Jaffino Stargen | D. Jaffino Stargen, S. Shankaranarayanan, and Saurya Das | Polymer quantization and advanced gravitational wave detector | v1: 12 pages, 4 figures; v2: 13 pages, 4 figures; Accepted in Phys.
Rev. D | Phys. Rev. D 100, 086007 (2019) | 10.1103/PhysRevD.100.086007 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the observable consequences of Planck scale effects in the
advanced gravitational wave detector by polymer quantizing the optical field in
the arms of the interferometer. We construct a new set of polymer-modified
creation and annihilation operators to quantize the optical field. Employing
these polymer-modified operators, we obtain the fluctuations in the radiation
pressure on the end mirrors and the number of output photons. We compare our
results with the standard quantization scheme and corrections from the
Generalized Uncertainty Principle.
| [
{
"created": "Fri, 12 Jul 2019 17:31:18 GMT",
"version": "v1"
},
{
"created": "Tue, 24 Sep 2019 04:55:43 GMT",
"version": "v2"
}
] | 2019-10-18 | [
[
"Stargen",
"D. Jaffino",
""
],
[
"Shankaranarayanan",
"S.",
""
],
[
"Das",
"Saurya",
""
]
] | We investigate the observable consequences of Planck scale effects in the advanced gravitational wave detector by polymer quantizing the optical field in the arms of the interferometer. We construct a new set of polymer-modified creation and annihilation operators to quantize the optical field. Employing these polymer-modified operators, we obtain the fluctuations in the radiation pressure on the end mirrors and the number of output photons. We compare our results with the standard quantization scheme and corrections from the Generalized Uncertainty Principle. |
2003.04416 | Vittorio De Falco Dr | Vittorio De Falco, Emmanuele Battista | Poynting-Robertson effect as a dissipative system in general relativity | 13 pages, 3 figures; Accepted on Physical Review D. Much of this work
appeared previously as arXiv:1911.03197, which remains un-published | null | 10.1103/PhysRevD.101.064040 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We determine for the first time in the literature the analytic form of the
Rayleigh potential of the general relativistic Poynting-Robertson effect. The
employed procedure is based on the use of an integrating factor and a new
integration strategy where the test particle's dissipated energy represents the
fundamental variable. The obtained results and their implications are
discussed. Finally, concluding remarks and future projects are drawn.
| [
{
"created": "Mon, 9 Mar 2020 21:12:23 GMT",
"version": "v1"
}
] | 2020-03-20 | [
[
"De Falco",
"Vittorio",
""
],
[
"Battista",
"Emmanuele",
""
]
] | We determine for the first time in the literature the analytic form of the Rayleigh potential of the general relativistic Poynting-Robertson effect. The employed procedure is based on the use of an integrating factor and a new integration strategy where the test particle's dissipated energy represents the fundamental variable. The obtained results and their implications are discussed. Finally, concluding remarks and future projects are drawn. |
2008.08689 | M. B. Paranjape | M. B. Paranjape | You can see a clock running backwards in time | 9 pages, 2 figures, 2020 Gravity Research Foundation Essay
Competition Honourable Mention | null | 10.1142/S0218271820430166 | UdeM-GPP-TH-20-282 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The epitome of acausal or anti-chronological behaviour would be to see a
clock running backwards in time. In this essay we point out that this is indeed
possible, but there is no problem with causality. What you see isn't what is
really happening. Locally, causality is always respected. However our
observation should be cause for pause to astronomers and cosmologists, who
strictly observe events occurring at very large distances or very long ago and
certainly not locally. It can be that what you see isn't what you necessarily
get.
| [
{
"created": "Wed, 19 Aug 2020 22:23:03 GMT",
"version": "v1"
}
] | 2021-02-03 | [
[
"Paranjape",
"M. B.",
""
]
] | The epitome of acausal or anti-chronological behaviour would be to see a clock running backwards in time. In this essay we point out that this is indeed possible, but there is no problem with causality. What you see isn't what is really happening. Locally, causality is always respected. However our observation should be cause for pause to astronomers and cosmologists, who strictly observe events occurring at very large distances or very long ago and certainly not locally. It can be that what you see isn't what you necessarily get. |
1810.07388 | Parthapratim Pradhan | Parthapratim Pradhan | Extended Phase Space Thermodynamics of Black Holes in Massive Gravity | Accepted for publication in Modern Physics Letters A (MPLA) | Modern Physics Letters AVol. 34, No. 09, 1950063 (2019) | 10.1142/S0217732319500639 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the extended phase space thermodynamics of black holes in massive
gravity. Particularly, we examine the critical behaviour of this black hole
using the extended phase space formalism. Extended phase space in a sense that
in which the cosmological constant should be treated as a thermodynamic
pressure and its conjugate variable as a thermodynamic volume. In this phase
space, we derive the black hole equation of state, the critical pressure, the
critical volume and the critical temperature at the critical point. We also
derive the critical ratio of this black hole. Moreover, we derive the black
hole reduced equation of state in terms of the reduced pressure, the reduced
volume and the reduced temperature. Furthermore, we examine the Ehrenfest
equations of black holes in massive gravity in the extended phase space at the
critical point. We show that the Ehrenfest equations are satisfied of this
black hole and the black hole encounters a second order phase transition at the
critical point in the said phase space. This is re-examined by evaluating the
Pregogine-Defay ratio~($\varPi$). We determine the value of this ratio is
$\varPi=1$. The outcome of this study is completely analogous to the nature of
liquid-gas phase transition at the critical point. This investigation also
further gives us the profound understanding between the black hole of massive
gravity with the liquid-gas system.
| [
{
"created": "Wed, 17 Oct 2018 05:22:55 GMT",
"version": "v1"
},
{
"created": "Wed, 26 Dec 2018 05:09:07 GMT",
"version": "v2"
}
] | 2019-04-15 | [
[
"Pradhan",
"Parthapratim",
""
]
] | We study the extended phase space thermodynamics of black holes in massive gravity. Particularly, we examine the critical behaviour of this black hole using the extended phase space formalism. Extended phase space in a sense that in which the cosmological constant should be treated as a thermodynamic pressure and its conjugate variable as a thermodynamic volume. In this phase space, we derive the black hole equation of state, the critical pressure, the critical volume and the critical temperature at the critical point. We also derive the critical ratio of this black hole. Moreover, we derive the black hole reduced equation of state in terms of the reduced pressure, the reduced volume and the reduced temperature. Furthermore, we examine the Ehrenfest equations of black holes in massive gravity in the extended phase space at the critical point. We show that the Ehrenfest equations are satisfied of this black hole and the black hole encounters a second order phase transition at the critical point in the said phase space. This is re-examined by evaluating the Pregogine-Defay ratio~($\varPi$). We determine the value of this ratio is $\varPi=1$. The outcome of this study is completely analogous to the nature of liquid-gas phase transition at the critical point. This investigation also further gives us the profound understanding between the black hole of massive gravity with the liquid-gas system. |
1008.3345 | Sabine Hossenfelder | Xavier Calmet, Sabine Hossenfelder, Roberto Percacci | Deformed Special Relativity from Asymptotically Safe Gravity | replaced with published version | Phys.Rev.D82:124024,2010 | 10.1103/PhysRevD.82.124024 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | By studying the notion of a fundamentally minimal length scale in
asymptotically safe gravity we find that a specific version of deformed special
relativity (DSR) naturally arises in this approach. We then consider two
thought experiments to examine the interpretation of the scenario and discuss
similarities and differences to other approaches to DSR.
| [
{
"created": "Thu, 19 Aug 2010 16:31:53 GMT",
"version": "v1"
},
{
"created": "Mon, 20 Dec 2010 14:18:18 GMT",
"version": "v2"
}
] | 2010-12-23 | [
[
"Calmet",
"Xavier",
""
],
[
"Hossenfelder",
"Sabine",
""
],
[
"Percacci",
"Roberto",
""
]
] | By studying the notion of a fundamentally minimal length scale in asymptotically safe gravity we find that a specific version of deformed special relativity (DSR) naturally arises in this approach. We then consider two thought experiments to examine the interpretation of the scenario and discuss similarities and differences to other approaches to DSR. |
gr-qc/0510068 | Marc-Thierry Jaekel | Marc-Thierry Jaekel and Serge Reynaud | Post-Einsteinian tests of gravitation | 19 pages Corrected typos | Class. Quantum Grav. 23 (2006) 777-798 | 10.1088/0264-9381/23/3/015 | LPTENS-05/34 | gr-qc | null | Einstein gravitation theory can be extended by preserving its geometrical
nature but changing the relation between curvature and energy-momentum tensors.
This change accounts for radiative corrections, replacing the Newton
gravitation constant by two running couplings which depend on scale and differ
in the two sectors of traceless and traced tensors. The metric and curvature
tensors in the field of the Sun, which were obtained in previous papers within
a linearized approximation, are then calculated without this restriction.
Modifications of gravitational effects on geodesics are then studied, allowing
one to explore phenomenological consequences of extensions lying in the
vicinity of general relativity. Some of these extended theories are able to
account for the Pioneer anomaly while remaining compatible with tests involving
the motion of planets. The PPN Ansatz corresponds to peculiar extensions of
general relativity which do not have the ability to meet this compatibility
challenge.
| [
{
"created": "Fri, 14 Oct 2005 06:39:32 GMT",
"version": "v1"
},
{
"created": "Fri, 4 Nov 2005 16:46:32 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Jaekel",
"Marc-Thierry",
""
],
[
"Reynaud",
"Serge",
""
]
] | Einstein gravitation theory can be extended by preserving its geometrical nature but changing the relation between curvature and energy-momentum tensors. This change accounts for radiative corrections, replacing the Newton gravitation constant by two running couplings which depend on scale and differ in the two sectors of traceless and traced tensors. The metric and curvature tensors in the field of the Sun, which were obtained in previous papers within a linearized approximation, are then calculated without this restriction. Modifications of gravitational effects on geodesics are then studied, allowing one to explore phenomenological consequences of extensions lying in the vicinity of general relativity. Some of these extended theories are able to account for the Pioneer anomaly while remaining compatible with tests involving the motion of planets. The PPN Ansatz corresponds to peculiar extensions of general relativity which do not have the ability to meet this compatibility challenge. |
1011.4618 | Adriano Contillo | Adriano Contillo | Evolution of cosmological perturbations in an RG-driven inflationary
scenario | 18 pages; improved discussion and references added; fitted to match
published version | Phys.Rev.D83:085016,2011 | 10.1103/PhysRevD.83.085016 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A gauge-invariant, linear cosmological perturbation theory of an almost
homogeneous and isotropic universe with dynamically evolving Newton constant G
and cosmological constant $\Lambda$ is presented. The equations governing the
evolution of the comoving fractional spatial gradients of the matter density, G
and $\Lambda$ are thus obtained. Explicit solutions are discussed in
cosmologies, featuring an accelerated expansion, where both G and $\Lambda$
vary according to renormalization group equations in the vicinity of an
ultraviolet fixed point. Finally, a similar analysis is carried out in the late
universe regime described by the part of the renormalization group trajectory
close to the gaussian fixed point.
| [
{
"created": "Sat, 20 Nov 2010 22:45:03 GMT",
"version": "v1"
},
{
"created": "Wed, 13 Apr 2011 08:49:50 GMT",
"version": "v2"
}
] | 2011-04-22 | [
[
"Contillo",
"Adriano",
""
]
] | A gauge-invariant, linear cosmological perturbation theory of an almost homogeneous and isotropic universe with dynamically evolving Newton constant G and cosmological constant $\Lambda$ is presented. The equations governing the evolution of the comoving fractional spatial gradients of the matter density, G and $\Lambda$ are thus obtained. Explicit solutions are discussed in cosmologies, featuring an accelerated expansion, where both G and $\Lambda$ vary according to renormalization group equations in the vicinity of an ultraviolet fixed point. Finally, a similar analysis is carried out in the late universe regime described by the part of the renormalization group trajectory close to the gaussian fixed point. |
1105.1213 | Xiao Zhang | Zhuobin Liang and Xiao Zhang | Spacelike hypersurfaces with negative total energy in de Sitter
spacetime | 11 pages, final version, to appear in J. Math. Phys | null | 10.1063/1.3682242 | null | gr-qc hep-th math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | De Sitter spacetime can be separated into two parts along two kinds of
hypersurfaces and the half-de Sitter spacetimes are covered by the planar and
hyperbolic coordinates respectively. Two positive energy theorems were proved
previously for certain $\P$-asymptotically de Sitter and $\H$-asymptotically de
Sitter initial data sets by the second author and collaborators. These initial
data sets are asymptotic to time slices of the two kinds of half-de Sitter
spacetimes respectively, and their mean curvatures are bounded from above by
certain constants. While the mean curvatures violate these conditions, the
spacelike hypersurfaces with negative total energy in the two kinds of half-de
Sitter spacetimes are constructed in this short paper.
| [
{
"created": "Fri, 6 May 2011 02:26:15 GMT",
"version": "v1"
},
{
"created": "Thu, 19 Jan 2012 12:18:59 GMT",
"version": "v2"
}
] | 2015-05-28 | [
[
"Liang",
"Zhuobin",
""
],
[
"Zhang",
"Xiao",
""
]
] | De Sitter spacetime can be separated into two parts along two kinds of hypersurfaces and the half-de Sitter spacetimes are covered by the planar and hyperbolic coordinates respectively. Two positive energy theorems were proved previously for certain $\P$-asymptotically de Sitter and $\H$-asymptotically de Sitter initial data sets by the second author and collaborators. These initial data sets are asymptotic to time slices of the two kinds of half-de Sitter spacetimes respectively, and their mean curvatures are bounded from above by certain constants. While the mean curvatures violate these conditions, the spacelike hypersurfaces with negative total energy in the two kinds of half-de Sitter spacetimes are constructed in this short paper. |
1010.2481 | Sean Gryb B | Henrique Gomes, Sean Gryb and Tim Koslowski | Einstein gravity as a 3D conformally invariant theory | 27 pages. Published version (minor changes and corrections) | Class.Quant.Grav.28:045005,2011 | 10.1088/0264-9381/28/4/045005 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We give an alternative description of the physical content of general
relativity that does not require a Lorentz invariant spacetime. Instead, we
find that gravity admits a dual description in terms of a theory where local
size is irrelevant. The dual theory is invariant under foliation preserving
3-diffeomorphisms and 3D conformal transformations that preserve the 3-volume
(for the spatially compact case). Locally, this symmetry is identical to that
of Horava-Lifshitz gravity in the high energy limit but our theory is
equivalent to Einstein gravity. Specifically, we find that the solutions of
general relativity, in a gauge where the spatial hypersurfaces have constant
mean extrinsic curvature, can be mapped to solutions of a particular gauge
fixing of the dual theory. Moreover, this duality is not accidental. We provide
a general geometric picture for our procedure that allows us to trade foliation
invariance for conformal invariance. The dual theory provides a new proposal
for the theory space of quantum gravity.
| [
{
"created": "Tue, 12 Oct 2010 19:40:08 GMT",
"version": "v1"
},
{
"created": "Mon, 28 Mar 2011 22:45:09 GMT",
"version": "v2"
}
] | 2011-03-30 | [
[
"Gomes",
"Henrique",
""
],
[
"Gryb",
"Sean",
""
],
[
"Koslowski",
"Tim",
""
]
] | We give an alternative description of the physical content of general relativity that does not require a Lorentz invariant spacetime. Instead, we find that gravity admits a dual description in terms of a theory where local size is irrelevant. The dual theory is invariant under foliation preserving 3-diffeomorphisms and 3D conformal transformations that preserve the 3-volume (for the spatially compact case). Locally, this symmetry is identical to that of Horava-Lifshitz gravity in the high energy limit but our theory is equivalent to Einstein gravity. Specifically, we find that the solutions of general relativity, in a gauge where the spatial hypersurfaces have constant mean extrinsic curvature, can be mapped to solutions of a particular gauge fixing of the dual theory. Moreover, this duality is not accidental. We provide a general geometric picture for our procedure that allows us to trade foliation invariance for conformal invariance. The dual theory provides a new proposal for the theory space of quantum gravity. |
2306.04373 | Marion Pillas | M. Pillas, T. Dal Canton, C. Stachie, B. Piotrzkowski, F. Hayes, R.
Hamburg, E. Burns, J. Wood, P. A. Duverne, N. Christensen | Deep Multimessenger Search for Compact Binary Mergers in LIGO, Virgo,
and Fermi/GBM Data from 2016-2017 | 22 pages, 16 figures | ApJ 956 56 (2023) | 10.3847/1538-4357/acf458 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | GW170817-GRB 170817A provided the first observation of gravitational waves
from a neutron star merger with associated transient counterparts across the
entire electromagnetic spectrum. This discovery demonstrated the
long-hypothesized association between short gamma-ray bursts and neutron star
mergers. More joint detections are needed to explore the relation between the
parameters inferred from the gravitational wave and the properties of the
gamma-ray burst signal. We developed a joint multimessenger analysis of LIGO,
Virgo, and Fermi/GBM data designed for detecting weak gravitational-wave
transients associated with weak gamma-ray bursts. As such, it does not start
from confident (GWTC-1) events only. Instead, we take the full list of existing
compact binary coalescence triggers generated with the PyCBC pipeline from the
second Gravitational-Wave Observing Run (O2), and reanalyze the entire set of
public Fermi/GBM data covering this observing run to generate a corresponding
set of gamma-ray burst candidate triggers. We then search for coincidences
between the gravitational-wave and gamma-ray burst triggers without requiring a
confident detection in any channel. The candidate coincidences are ranked
according to a statistic combining each candidate's strength in
gravitational-wave and gamma-ray data, their time proximity, and the overlap of
their sky localization. The ranking is then converted to a false alarm rate
using time shifts between the gravitational-wave and gamma-ray burst triggers.
We present the results using O2 triggers, which allowed us to check the
validity of our method against GW170817-GRB 170817A. We also discuss the
different configurations tested to maximize the significance of the joint
detection.
| [
{
"created": "Wed, 7 Jun 2023 12:13:20 GMT",
"version": "v1"
},
{
"created": "Fri, 20 Oct 2023 14:33:42 GMT",
"version": "v2"
},
{
"created": "Wed, 6 Mar 2024 08:04:53 GMT",
"version": "v3"
}
] | 2024-03-07 | [
[
"Pillas",
"M.",
""
],
[
"Canton",
"T. Dal",
""
],
[
"Stachie",
"C.",
""
],
[
"Piotrzkowski",
"B.",
""
],
[
"Hayes",
"F.",
""
],
[
"Hamburg",
"R.",
""
],
[
"Burns",
"E.",
""
],
[
"Wood",
"J.",
""
],
[
"Duverne",
"P. A.",
""
],
[
"Christensen",
"N.",
""
]
] | GW170817-GRB 170817A provided the first observation of gravitational waves from a neutron star merger with associated transient counterparts across the entire electromagnetic spectrum. This discovery demonstrated the long-hypothesized association between short gamma-ray bursts and neutron star mergers. More joint detections are needed to explore the relation between the parameters inferred from the gravitational wave and the properties of the gamma-ray burst signal. We developed a joint multimessenger analysis of LIGO, Virgo, and Fermi/GBM data designed for detecting weak gravitational-wave transients associated with weak gamma-ray bursts. As such, it does not start from confident (GWTC-1) events only. Instead, we take the full list of existing compact binary coalescence triggers generated with the PyCBC pipeline from the second Gravitational-Wave Observing Run (O2), and reanalyze the entire set of public Fermi/GBM data covering this observing run to generate a corresponding set of gamma-ray burst candidate triggers. We then search for coincidences between the gravitational-wave and gamma-ray burst triggers without requiring a confident detection in any channel. The candidate coincidences are ranked according to a statistic combining each candidate's strength in gravitational-wave and gamma-ray data, their time proximity, and the overlap of their sky localization. The ranking is then converted to a false alarm rate using time shifts between the gravitational-wave and gamma-ray burst triggers. We present the results using O2 triggers, which allowed us to check the validity of our method against GW170817-GRB 170817A. We also discuss the different configurations tested to maximize the significance of the joint detection. |
gr-qc/0007026 | Vladimir Kassandrov | V.V.Kassandrov, V.N.Trishin | "Particle-like" singular solutions in Einstein-Maxwell theory and in
algebraic dynamics | 10 pages, 2 figures, 10th Russian gravitation conference, Vladimir,
1999 | Grav.Cosmol.5:272-276,1999 | null | null | gr-qc | null | Foundations of algebrodynamics based on earlier proposed equations of
biquaternionic holomorphy are briefly expounded. Free Maxwell and Yang-Mills
Eqs. are satisfied identically on the solutions of primary system which is also
related to the Eqs. of shear-free null congruences (SFC), and through them - to
the Einstein-Maxwell electrovacuum system. Kerr theorem for SFC reduces the
basic system to one algebraic equation, so that with each solution of the
latter some (singular) solution of vacuum Eqs. may be associated. We present
some exact solutions of basic algebraic and of related field Eqs. with compact
structure of singularities of electromagnetic field, in particular having the
form of figure "8" curve. Fundamental solution to primary system is analogous
to the metric and fields of the Kerr-Newman solution. In addition, in the
framework of algebraic dynamics the value of electric charge for this solution
is strictly fixed in magnitude and may be set equal to the elementary charge.
| [
{
"created": "Thu, 13 Jul 2000 15:31:04 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"Kassandrov",
"V. V.",
""
],
[
"Trishin",
"V. N.",
""
]
] | Foundations of algebrodynamics based on earlier proposed equations of biquaternionic holomorphy are briefly expounded. Free Maxwell and Yang-Mills Eqs. are satisfied identically on the solutions of primary system which is also related to the Eqs. of shear-free null congruences (SFC), and through them - to the Einstein-Maxwell electrovacuum system. Kerr theorem for SFC reduces the basic system to one algebraic equation, so that with each solution of the latter some (singular) solution of vacuum Eqs. may be associated. We present some exact solutions of basic algebraic and of related field Eqs. with compact structure of singularities of electromagnetic field, in particular having the form of figure "8" curve. Fundamental solution to primary system is analogous to the metric and fields of the Kerr-Newman solution. In addition, in the framework of algebraic dynamics the value of electric charge for this solution is strictly fixed in magnitude and may be set equal to the elementary charge. |
2105.00253 | Hiroki Takeda | Hiroki Takeda, Soichiro Morisaki, and Atsushi Nishizawa | Scalar-tensor mixed polarization search of gravitational waves | 6 pages, 3 figures | null | 10.1103/PhysRevD.105.084019 | LIGO-P2100137 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An additional scalar degree of freedom for a gravitational wave is often
predicted in theories of gravity beyond general relativity and can be used for
a model-agnostic test of gravity. In this letter, we report the direct search
for the scalar-tensor mixed polarization modes of gravitational waves from
compact binaries in a strong regime of gravity by analyzing the data of
GW170814 and GW170817, which are the merger events of binary black holes and
binary neutron stars, respectively. Consequently, we obtain the constraints on
the ratio of scalar-mode amplitude to tensor-mode amplitude: $\lesssim 0.20$
for GW170814 and $\lesssim 0.068$ for GW170817, which are the tightest
constraints on the scalar amplitude in a strong regime of gravity before
merger.
| [
{
"created": "Sat, 1 May 2021 14:06:24 GMT",
"version": "v1"
},
{
"created": "Wed, 8 Dec 2021 10:07:54 GMT",
"version": "v2"
}
] | 2022-04-27 | [
[
"Takeda",
"Hiroki",
""
],
[
"Morisaki",
"Soichiro",
""
],
[
"Nishizawa",
"Atsushi",
""
]
] | An additional scalar degree of freedom for a gravitational wave is often predicted in theories of gravity beyond general relativity and can be used for a model-agnostic test of gravity. In this letter, we report the direct search for the scalar-tensor mixed polarization modes of gravitational waves from compact binaries in a strong regime of gravity by analyzing the data of GW170814 and GW170817, which are the merger events of binary black holes and binary neutron stars, respectively. Consequently, we obtain the constraints on the ratio of scalar-mode amplitude to tensor-mode amplitude: $\lesssim 0.20$ for GW170814 and $\lesssim 0.068$ for GW170817, which are the tightest constraints on the scalar amplitude in a strong regime of gravity before merger. |
gr-qc/9305015 | null | Donald Marolf | An illustration of 2+1 gravity loop transform troubles | 6 pages, latex, SU-GP-93/3-4 | null | null | null | gr-qc | null | A nonperturbative approach to quantum gravity that has generated much
discussion is the attempt to construct a ``loop representation." Despite it's
success in linear quantum theories and a part of 2+1 quantum gravity, it has
recently been noticed that difficulties arise with loop representations in a
different ``sector" of 2+1 gravity. The problems are related to the use of the
``loop transform" in the construction of the loop representation. We illustrate
these difficulties by exploring an analogy based on the Mellin transform which
allows us to work in a context that is both mathematically and physically
simple and that does not require an understanding either of loop
representations or of 2+1 gravity.
| [
{
"created": "Tue, 18 May 1993 16:57:00 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Marolf",
"Donald",
""
]
] | A nonperturbative approach to quantum gravity that has generated much discussion is the attempt to construct a ``loop representation." Despite it's success in linear quantum theories and a part of 2+1 quantum gravity, it has recently been noticed that difficulties arise with loop representations in a different ``sector" of 2+1 gravity. The problems are related to the use of the ``loop transform" in the construction of the loop representation. We illustrate these difficulties by exploring an analogy based on the Mellin transform which allows us to work in a context that is both mathematically and physically simple and that does not require an understanding either of loop representations or of 2+1 gravity. |
0804.4816 | Craig Robinson Dr | C.A.K. Robinson, B.S. Sathyaprakash, Anand S. Sengupta | A geometric algorithm for efficient coincident detection of
gravitational waves | 25 pages, 2 figures | Phys.Rev.D78:062002,2008 | 10.1103/PhysRevD.78.062002 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Data from a network of gravitational wave detectors can be analyzed in
coincidence to increase detection confidence and reduce non-stationarity of the
background. We propose and explore a geometric algorithm to combine the data
from a network of detectors. The algorithm makes optimal use of the variances
and covariances that exist amongst the different parameters of a signal in a
coincident detection of events. The new algorithm essentially associates with
each trigger ellipsoidal regions in parameter space defined by the covariance
matrix. Triggers from different detectors are deemed to be in coincidence if
their ellipsoids have a non-zero overlap. Compared to an algorithm that uses
uncorrelated windows separately for each of the signal parameters, the new
algorithm greatly reduces the background rate thereby increasing detection
efficiency at a given false alarm rate.
| [
{
"created": "Wed, 30 Apr 2008 13:41:50 GMT",
"version": "v1"
}
] | 2009-02-20 | [
[
"Robinson",
"C. A. K.",
""
],
[
"Sathyaprakash",
"B. S.",
""
],
[
"Sengupta",
"Anand S.",
""
]
] | Data from a network of gravitational wave detectors can be analyzed in coincidence to increase detection confidence and reduce non-stationarity of the background. We propose and explore a geometric algorithm to combine the data from a network of detectors. The algorithm makes optimal use of the variances and covariances that exist amongst the different parameters of a signal in a coincident detection of events. The new algorithm essentially associates with each trigger ellipsoidal regions in parameter space defined by the covariance matrix. Triggers from different detectors are deemed to be in coincidence if their ellipsoids have a non-zero overlap. Compared to an algorithm that uses uncorrelated windows separately for each of the signal parameters, the new algorithm greatly reduces the background rate thereby increasing detection efficiency at a given false alarm rate. |
1102.5096 | Piero Nicolini | Robert B. Mann and Piero Nicolini | Cosmological production of noncommutative black holes | 13 pages, 10 figures, version matching that published on PRD | Phys.Rev.D84:064014,2011 | 10.1103/PhysRevD.84.064014 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the pair creation of noncommutative black holes in a
background with positive cosmological constant. As a first step we derive the
noncommutative geometry inspired Schwarzschild deSitter solution. By varying
the mass and the cosmological constant parameters, we find several spacetimes
compatible with the new solution: positive mass spacetimes admit one
cosmological horizon and two, one or no black hole horizons, while negative
mass spacetimes have just a cosmological horizon. These new black holes share
the properties of the corresponding asymptotically flat solutions, including
the non-singular core and thermodynamic stability in the final phase of the
evaporation. As a second step we determine the action which generates the
matter sector of gravitational field equations and we construct instantons
describing the pair production of black holes and the other admissible
topologies. As a result we find that for current values of the cosmological
constant the deSitter background is quantum mechanically stable according to
experience. However positive mass noncommutative black holes and solitons would
have plentifully been produced during inflationary times for Planckian values
of the cosmological constant. As a special result we find that, in these early
epochs of the universe, Planck size black holes production would have been
largely disfavoured. We also find a potential instability for production of
negative-mass solitons.
| [
{
"created": "Thu, 24 Feb 2011 21:00:05 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Sep 2011 15:46:03 GMT",
"version": "v2"
}
] | 2011-09-14 | [
[
"Mann",
"Robert B.",
""
],
[
"Nicolini",
"Piero",
""
]
] | We investigate the pair creation of noncommutative black holes in a background with positive cosmological constant. As a first step we derive the noncommutative geometry inspired Schwarzschild deSitter solution. By varying the mass and the cosmological constant parameters, we find several spacetimes compatible with the new solution: positive mass spacetimes admit one cosmological horizon and two, one or no black hole horizons, while negative mass spacetimes have just a cosmological horizon. These new black holes share the properties of the corresponding asymptotically flat solutions, including the non-singular core and thermodynamic stability in the final phase of the evaporation. As a second step we determine the action which generates the matter sector of gravitational field equations and we construct instantons describing the pair production of black holes and the other admissible topologies. As a result we find that for current values of the cosmological constant the deSitter background is quantum mechanically stable according to experience. However positive mass noncommutative black holes and solitons would have plentifully been produced during inflationary times for Planckian values of the cosmological constant. As a special result we find that, in these early epochs of the universe, Planck size black holes production would have been largely disfavoured. We also find a potential instability for production of negative-mass solitons. |
1512.08682 | Hakan Cebeci | Hakan Cebeci, N\"ulifer \"Ozdemir, Se\c{c}il \c{S}entorun | Motion of the charged test particles in Kerr-Newman-Taub-NUT spacetime
and analytical solutions | 42 pages, improved version, to appear in PRD | Phys. Rev. D 93, 104031 (2016) | 10.1103/PhysRevD.93.104031 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we study the motion of charged test particles in
Kerr-Newman-Taub-NUT spacetime. We analyze the angular and the radial parts of
the orbit equations and examine the possible orbit types. We also investigate
the spherical orbits and their stabilities. Furthermore, we obtain the
analytical solutions of the equations of motion and express them in terms of
Jacobian and Weierstrass elliptic functions. Finally, we discuss the
observables of the bound motion and calculate the perihelion shift and
Lense-Thirring effect for three dimensional bound orbits.
| [
{
"created": "Tue, 29 Dec 2015 13:44:15 GMT",
"version": "v1"
},
{
"created": "Mon, 9 May 2016 14:32:57 GMT",
"version": "v2"
}
] | 2016-05-25 | [
[
"Cebeci",
"Hakan",
""
],
[
"Özdemir",
"Nülifer",
""
],
[
"Şentorun",
"Seçil",
""
]
] | In this work, we study the motion of charged test particles in Kerr-Newman-Taub-NUT spacetime. We analyze the angular and the radial parts of the orbit equations and examine the possible orbit types. We also investigate the spherical orbits and their stabilities. Furthermore, we obtain the analytical solutions of the equations of motion and express them in terms of Jacobian and Weierstrass elliptic functions. Finally, we discuss the observables of the bound motion and calculate the perihelion shift and Lense-Thirring effect for three dimensional bound orbits. |
gr-qc/0410041 | Rituparno Goswami | Rituparno Goswami, Pankaj S. Joshi, Cenalo Vaz, Louis Witten | A Time-Like Naked Singularity | 4 pages, Revtex4, To appear in Physical Review D | Phys.Rev. D70 (2004) 084038 | 10.1103/PhysRevD.70.084038 | null | gr-qc | null | We construct a class of spherically symmetric collapse models in which a
naked singularity may develop as the end state of collapse. The matter
distribution considered has negative radial and tangential pressures, but the
weak energy condition is obeyed throughout. The singularity forms at the center
of the collapsing cloud and continues to be visible for a finite time. The
duration of visibility depends on the nature of energy distribution. Hence the
causal structure of the resulting singularity depends on the nature of the mass
function chosen for the cloud. We present a general model in which the naked
singularity formed is timelike, neither pointlike nor null. Our work represents
a step toward clarifying the necessary conditions for the validity of the
Cosmic Censorship Conjecture.
| [
{
"created": "Fri, 8 Oct 2004 17:48:39 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Goswami",
"Rituparno",
""
],
[
"Joshi",
"Pankaj S.",
""
],
[
"Vaz",
"Cenalo",
""
],
[
"Witten",
"Louis",
""
]
] | We construct a class of spherically symmetric collapse models in which a naked singularity may develop as the end state of collapse. The matter distribution considered has negative radial and tangential pressures, but the weak energy condition is obeyed throughout. The singularity forms at the center of the collapsing cloud and continues to be visible for a finite time. The duration of visibility depends on the nature of energy distribution. Hence the causal structure of the resulting singularity depends on the nature of the mass function chosen for the cloud. We present a general model in which the naked singularity formed is timelike, neither pointlike nor null. Our work represents a step toward clarifying the necessary conditions for the validity of the Cosmic Censorship Conjecture. |
1006.3860 | Mauricio Bellini | Pablo Alejandro Sanchez, Jesus Martin Romero, Mauricio Bellini (Mar
del Plata University & IFIMAR-CONICET) | Analytical treatment of SUSY Quasi-normal modes in a non-rotating
Schwarzschild black hole | Version to be published in European Physical Journal C | Eur.Phys.J.C71:1526,2011 | 10.1140/epjc/s10052-010-1526-9 | null | gr-qc astro-ph.HE hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We use the Fock-Ivanenko formalism to obtain the Dirac equation which
describes the interaction of a massless 1/2-spin neutral fermion with a
gravitational field around a Schwarzschild black hole (BH). We obtain
approximated analytical solutions for the eigenvalues of the energy
(quasi-normal frequencies) and their corresponding eigenstates (quasi-normal
states). The interesting result is that all the excited states [and their
supersymmetric (SUSY) partners] have a purely imaginary frequency, which can be
expressed in terms of the Hawking temperature. Furthermore, as one expects for
SUSY Hamiltonians, the isolated bottom state has a real null energy eigenvalue.
| [
{
"created": "Sat, 19 Jun 2010 11:46:43 GMT",
"version": "v1"
},
{
"created": "Thu, 19 Aug 2010 15:38:53 GMT",
"version": "v2"
},
{
"created": "Mon, 15 Nov 2010 21:38:54 GMT",
"version": "v3"
},
{
"created": "Wed, 5 Jan 2011 21:55:06 GMT",
"version": "v4"
}
] | 2011-03-03 | [
[
"Sanchez",
"Pablo Alejandro",
"",
"Mar\n del Plata University & IFIMAR-CONICET"
],
[
"Romero",
"Jesus Martin",
"",
"Mar\n del Plata University & IFIMAR-CONICET"
],
[
"Bellini",
"Mauricio",
"",
"Mar\n del Plata University & IFIMAR-CONICET"
]
] | We use the Fock-Ivanenko formalism to obtain the Dirac equation which describes the interaction of a massless 1/2-spin neutral fermion with a gravitational field around a Schwarzschild black hole (BH). We obtain approximated analytical solutions for the eigenvalues of the energy (quasi-normal frequencies) and their corresponding eigenstates (quasi-normal states). The interesting result is that all the excited states [and their supersymmetric (SUSY) partners] have a purely imaginary frequency, which can be expressed in terms of the Hawking temperature. Furthermore, as one expects for SUSY Hamiltonians, the isolated bottom state has a real null energy eigenvalue. |
2302.05070 | Pardyumn Kumar Sahoo | Gaurav N. Gadbail, Simran Arora, P.K. Sahoo | Dark energy constraint on equation of state parameter in the Weyl type
$f(Q,T)$ gravity | Annals of Physics accepted version | Annals of Physics, 451 (2023) 169244 | 10.1016/j.aop.2023.169244 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The equation of state parameter is a significant method for characterizing
dark energy models. We investigate the evolution of the equation of state
parameter with redshift using a Bayesian analysis of recent observational
datasets (the Cosmic Chronometer data (CC) and Pantheon samples). The
Chevallier-Polarski-Linder parametrization of the effective equation of state
parameter, $\omega_{eff}=\omega_0+\omega_a \left( \frac{z}{1+z}\right) $, where
$\omega_0$ and $\omega_a$ are free constants, is confined to the Weyl type
$f(Q,T)$ gravity, where $Q$ represents the non-metricity and $T$ is the trace
of the energy-momentum tensor. We observe the evolution of the deceleration
parameter $q$, the density parameter $\rho$, the pressure $p$, and the
effective equation of state parameter $\omega$. The cosmic data limit for
$\omega$ does not exclude the possibility of $\omega < -1$. It is seen that the
parameter $\omega$ shows a transition from deceleration to acceleration, as
well as a shift from $\omega>-1$ to $\omega<-1$.
| [
{
"created": "Fri, 10 Feb 2023 06:01:53 GMT",
"version": "v1"
}
] | 2023-02-15 | [
[
"Gadbail",
"Gaurav N.",
""
],
[
"Arora",
"Simran",
""
],
[
"Sahoo",
"P. K.",
""
]
] | The equation of state parameter is a significant method for characterizing dark energy models. We investigate the evolution of the equation of state parameter with redshift using a Bayesian analysis of recent observational datasets (the Cosmic Chronometer data (CC) and Pantheon samples). The Chevallier-Polarski-Linder parametrization of the effective equation of state parameter, $\omega_{eff}=\omega_0+\omega_a \left( \frac{z}{1+z}\right) $, where $\omega_0$ and $\omega_a$ are free constants, is confined to the Weyl type $f(Q,T)$ gravity, where $Q$ represents the non-metricity and $T$ is the trace of the energy-momentum tensor. We observe the evolution of the deceleration parameter $q$, the density parameter $\rho$, the pressure $p$, and the effective equation of state parameter $\omega$. The cosmic data limit for $\omega$ does not exclude the possibility of $\omega < -1$. It is seen that the parameter $\omega$ shows a transition from deceleration to acceleration, as well as a shift from $\omega>-1$ to $\omega<-1$. |
1908.02677 | Hans Oude Groeniger | Hans Oude Groeniger | On Bianchi type VI$_0$ spacetimes with orthogonal perfect fluid matter | 19 pages, 1 figure | Annales Henri Poincare 21 (2020), 3069-3094 | 10.1007/s00023-020-00934-0 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the asymptotic behaviour of Bianchi type VI$_0$ spacetimes with
orthogonal perfect fluid matter satisfying Einstein's equations. In particular,
we prove a conjecture due to Wainwright about the initial singularity of such
spacetimes. Using the expansion-normalized variables of Wainwright-Hsu, we
demonstrate that for a generic solution the initial singularity is vacuum
dominated, anisotropic and silent. In addition, by employing known results on
Bianchi backgrounds, we obtain convergence results on the asymptotics of
solutions to the Klein-Gordon equation on all backgrounds of this type, except
for one specific case.
| [
{
"created": "Wed, 7 Aug 2019 15:14:28 GMT",
"version": "v1"
},
{
"created": "Fri, 10 Nov 2023 16:19:27 GMT",
"version": "v2"
}
] | 2023-11-13 | [
[
"Groeniger",
"Hans Oude",
""
]
] | We study the asymptotic behaviour of Bianchi type VI$_0$ spacetimes with orthogonal perfect fluid matter satisfying Einstein's equations. In particular, we prove a conjecture due to Wainwright about the initial singularity of such spacetimes. Using the expansion-normalized variables of Wainwright-Hsu, we demonstrate that for a generic solution the initial singularity is vacuum dominated, anisotropic and silent. In addition, by employing known results on Bianchi backgrounds, we obtain convergence results on the asymptotics of solutions to the Klein-Gordon equation on all backgrounds of this type, except for one specific case. |
1404.0562 | Diego S\'aez | Neus Puchades and Diego S\'aez | Relativistic positioning: errors due to uncertainties in the satellite
world lines | 20 pages, 9 figures, published online in Astrophys. Space, Sci | Astrophys. Space Sci. (2014) | 10.1007/s10509-014-1908-9 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Global navigation satellite systems use appropriate satellite constellations
to get the coordinates of an user -close to Earth- in an almost inertial
reference system. We have simulated both GPS and GALILEO constellations.
Uncertainties in the satellite world lines lead to dominant positioning errors.
In this paper, a detailed analysis of these errors is developed inside a great
region surrounding Earth. This analysis is performed in the framework of the
so-called relativistic positioning systems. Our study is based on the Jacobian,
J, of the transformation giving the emission coordinates in terms of the
inertial ones. Around points of vanishing J, positioning errors are too large.
We show that, for any 4-tuple of satellites, the points with J=0 are located at
distances, D, from the Earth centre greater than about 2R/3, where R is the
radius of the satellite orbits which are assumed to be circumferences. Our
results strongly suggest that, for D-distances greater than 2R/3 and smaller
than 100000 km, a rather good positioning may be achieved by using appropriate
satellite 4-tuples without J=0 points located in the user vicinity. The way to
find these 4-tuples is discussed for arbitrary users with D<100000 km and,
then, preliminary considerations about satellite navigation at D<100000 km are
presented. Future work on the subject of space navigation -based on appropriate
simulations- is in progress.
| [
{
"created": "Wed, 2 Apr 2014 14:16:08 GMT",
"version": "v1"
}
] | 2014-04-03 | [
[
"Puchades",
"Neus",
""
],
[
"Sáez",
"Diego",
""
]
] | Global navigation satellite systems use appropriate satellite constellations to get the coordinates of an user -close to Earth- in an almost inertial reference system. We have simulated both GPS and GALILEO constellations. Uncertainties in the satellite world lines lead to dominant positioning errors. In this paper, a detailed analysis of these errors is developed inside a great region surrounding Earth. This analysis is performed in the framework of the so-called relativistic positioning systems. Our study is based on the Jacobian, J, of the transformation giving the emission coordinates in terms of the inertial ones. Around points of vanishing J, positioning errors are too large. We show that, for any 4-tuple of satellites, the points with J=0 are located at distances, D, from the Earth centre greater than about 2R/3, where R is the radius of the satellite orbits which are assumed to be circumferences. Our results strongly suggest that, for D-distances greater than 2R/3 and smaller than 100000 km, a rather good positioning may be achieved by using appropriate satellite 4-tuples without J=0 points located in the user vicinity. The way to find these 4-tuples is discussed for arbitrary users with D<100000 km and, then, preliminary considerations about satellite navigation at D<100000 km are presented. Future work on the subject of space navigation -based on appropriate simulations- is in progress. |
gr-qc/0701030 | Hiromi Saida | Hiromi Saida | Black hole evaporation in a heat bath as a nonequilibrium process and
its final fate | null | Class.Quant.Grav. 24 (2007) 691-722 | 10.1088/0264-9381/24/3/012 | null | gr-qc astro-ph hep-th | null | When a black hole evaporates, there arises a net energy flow from black hole
into its outside environment (heat bath). The existence of energy flow means
that the thermodynamic state of the whole system, which consists of the black
hole and the heat bath, is in a nonequilibrium state. Therefore, in order to
study the detail of evaporation process, the nonequilibrium effects of the
energy flow should be taken into account. Using the nonequilibrium
thermodynamics which has been formulated recently, this paper shows the
following: (1) Time scale of black hole evaporation in a heat bath becomes
shorter than that of the evaporation in an empty space (a situation without
heat bath), because a nonequilibrium effect of temperature difference between
the black hole and heat bath appears as a strong energy extraction from the
black hole by the heat bath. (2) Consequently a huge energy burst (stronger
than that of the evaporation in an empty space) arises at the end of
semi-classical stage of evaporation. (3) It is suggested that a remnant of
Planck size remains after the quantum stage of evaporation in order to
guarantee the increase of total entropy of the whole system.
| [
{
"created": "Thu, 4 Jan 2007 02:24:37 GMT",
"version": "v1"
},
{
"created": "Thu, 11 Jan 2007 01:30:25 GMT",
"version": "v2"
}
] | 2009-11-13 | [
[
"Saida",
"Hiromi",
""
]
] | When a black hole evaporates, there arises a net energy flow from black hole into its outside environment (heat bath). The existence of energy flow means that the thermodynamic state of the whole system, which consists of the black hole and the heat bath, is in a nonequilibrium state. Therefore, in order to study the detail of evaporation process, the nonequilibrium effects of the energy flow should be taken into account. Using the nonequilibrium thermodynamics which has been formulated recently, this paper shows the following: (1) Time scale of black hole evaporation in a heat bath becomes shorter than that of the evaporation in an empty space (a situation without heat bath), because a nonequilibrium effect of temperature difference between the black hole and heat bath appears as a strong energy extraction from the black hole by the heat bath. (2) Consequently a huge energy burst (stronger than that of the evaporation in an empty space) arises at the end of semi-classical stage of evaporation. (3) It is suggested that a remnant of Planck size remains after the quantum stage of evaporation in order to guarantee the increase of total entropy of the whole system. |
1610.05734 | Mohsen Fathi | Mohsen Fathi, Morteza Mohseni | Gravitational Collapse in Repulsive $R+\mu^4/R$ Gravity | 20 pages, 7 figures | Eur. Phys. J. Plus 131, 360 (2016) | 10.1140/epjp/i2016-16360-7 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we work out collapsing conditions for a spherical star in the
weak field limit of the $R+\mu^4/R$ gravity and discuss the importance of the
parameter $\mu$ to generate different criteria in the theory. Such criteria are
proved to be resulting in a variety of different fates for the evolution of the
outer shells of stars. Furthermore, we investigate the special case of
violating the first junction condition and point out corresponding
contradictions to the normal cases. These results show that the consistency of
the $R+\mu^4/R$ theory of gravity with the common astrophysical predictions
relies highly on the adoption of the parameter $\mu$ and satisfaction/violation
of the first junction condition. For those anomalous results, further
observational attempts are mandatory.
| [
{
"created": "Mon, 17 Oct 2016 06:34:55 GMT",
"version": "v1"
}
] | 2016-10-19 | [
[
"Fathi",
"Mohsen",
""
],
[
"Mohseni",
"Morteza",
""
]
] | In this paper we work out collapsing conditions for a spherical star in the weak field limit of the $R+\mu^4/R$ gravity and discuss the importance of the parameter $\mu$ to generate different criteria in the theory. Such criteria are proved to be resulting in a variety of different fates for the evolution of the outer shells of stars. Furthermore, we investigate the special case of violating the first junction condition and point out corresponding contradictions to the normal cases. These results show that the consistency of the $R+\mu^4/R$ theory of gravity with the common astrophysical predictions relies highly on the adoption of the parameter $\mu$ and satisfaction/violation of the first junction condition. For those anomalous results, further observational attempts are mandatory. |
gr-qc/9712004 | Plamen Fiziev | P. P. Fiziev | Spinless Matter in Transposed-Equi-Affine Theory of Gravity | 29 pages, latex, no figures. New Section on semiclassical limit of
wave equation added; old references rearranged; new references, remarks,
comments, and acknowledgments added; typos corrected | Gen.Rel.Grav. 30 (1998) 1341-1370 | 10.1023/A:1018800507761 | SU-FzF: 3/97 | gr-qc hep-th | null | We derive and discus the equations of motion for spinless matter:
relativistic spinless scalar fields, particles and fluids in the recently
proposed by A. Saa model of gravity with covariantly constant volume with
respect to the transposed connection in Einstein-Cartan spaces.
A new interpretation of this theory as a theory with variable Plank
"constant" is suggested.
We show that the consistency of the semiclassical limit of the wave equation
and classical motion dictates a new definite universal interaction of torsion
with massive fields.
| [
{
"created": "Mon, 1 Dec 1997 09:15:01 GMT",
"version": "v1"
},
{
"created": "Mon, 19 Jan 1998 08:38:09 GMT",
"version": "v2"
},
{
"created": "Sat, 16 May 1998 16:09:52 GMT",
"version": "v3"
}
] | 2015-06-25 | [
[
"Fiziev",
"P. P.",
""
]
] | We derive and discus the equations of motion for spinless matter: relativistic spinless scalar fields, particles and fluids in the recently proposed by A. Saa model of gravity with covariantly constant volume with respect to the transposed connection in Einstein-Cartan spaces. A new interpretation of this theory as a theory with variable Plank "constant" is suggested. We show that the consistency of the semiclassical limit of the wave equation and classical motion dictates a new definite universal interaction of torsion with massive fields. |
gr-qc/0612193 | Nikodem Poplawski | Nikodem J. Poplawski | Gravitation, electromagnetism and the cosmological constant in purely
affine gravity | 14 pages, extended and combined with gr-qc/0701176; published version | Int.J.Mod.Phys.D18:809-829,2009 | 10.1142/S0218271809014777 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Eddington Lagrangian in the purely affine formulation of general
relativity generates the Einstein equations with the cosmological constant. The
Ferraris-Kijowski purely affine Lagrangian for the electromagnetic field, which
has the form of the Maxwell Lagrangian with the metric tensor replaced by the
symmetrized Ricci tensor, is dynamically equivalent to the Einstein-Maxwell
Lagrangian in the metric formulation. We show that the sum of the two affine
Lagrangians is dynamically inequivalent to the sum of the analogous Lagrangians
in the metric-affine/metric formulation. We also show that such a construction
is valid only for weak electromagnetic fields. Therefore the purely affine
formulation that combines gravitation, electromagnetism and the cosmological
constant cannot be a simple sum of terms corresponding to separate fields.
Consequently, this formulation of electromagnetism seems to be unphysical,
unlike the purely metric and metric-affine pictures, unless the electromagnetic
field couples to the cosmological constant.
| [
{
"created": "Fri, 29 Dec 2006 20:50:16 GMT",
"version": "v1"
},
{
"created": "Wed, 31 Jan 2007 17:12:07 GMT",
"version": "v2"
},
{
"created": "Fri, 10 Jul 2009 23:55:14 GMT",
"version": "v3"
}
] | 2010-11-02 | [
[
"Poplawski",
"Nikodem J.",
""
]
] | The Eddington Lagrangian in the purely affine formulation of general relativity generates the Einstein equations with the cosmological constant. The Ferraris-Kijowski purely affine Lagrangian for the electromagnetic field, which has the form of the Maxwell Lagrangian with the metric tensor replaced by the symmetrized Ricci tensor, is dynamically equivalent to the Einstein-Maxwell Lagrangian in the metric formulation. We show that the sum of the two affine Lagrangians is dynamically inequivalent to the sum of the analogous Lagrangians in the metric-affine/metric formulation. We also show that such a construction is valid only for weak electromagnetic fields. Therefore the purely affine formulation that combines gravitation, electromagnetism and the cosmological constant cannot be a simple sum of terms corresponding to separate fields. Consequently, this formulation of electromagnetism seems to be unphysical, unlike the purely metric and metric-affine pictures, unless the electromagnetic field couples to the cosmological constant. |
gr-qc/9903093 | Juan A. Valiente | J.A. Valiente-Kroon | On Killing vector fields and Newman-Penrose constants | 23 pages, 8 eps figures. Submitted to J. Math. Phys | J.Math.Phys. 41 (2000) 898-923 | null | null | gr-qc | null | Asymptotically flat spacetimes with one Killing vector field are considered.
The Killing equations are solved asymptotically using polyhomogeneous
expansions (i.e. series in powers of 1/r an ln r), and solved order by order.
The solution to the leading terms of these expansions yield the asymptotic form
of the Killing vector field. The possible classes of Killing fields are
discussed by analysing their orbits on null infinity. The integrability
conditions of the Killing equations are used to obtain constraints on the
components of the Weyl tensor (\Psi_0, \Psi_1, \Psi_2) and on the shear
(\sigma). The behaviour of the solutions to the constraint equations is
studied. It is shown that for Killing fields that are non-supertranslational
the characteristics of the constraint equations are the orbits of the
restriction of the Killing field to null infinity. As an application,
boost-rotation symmetric spacetimes are considered. The constraints on \Psi_0
are used to study the behaviour of the coefficients that give rise to the
Newman-Penrose constants, if the spacetime is non-polyhomogeneous, or the
logarithmic Newman-Penrose constants if the spacetime is polyhomogeneous.
| [
{
"created": "Thu, 25 Mar 1999 19:32:45 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Valiente-Kroon",
"J. A.",
""
]
] | Asymptotically flat spacetimes with one Killing vector field are considered. The Killing equations are solved asymptotically using polyhomogeneous expansions (i.e. series in powers of 1/r an ln r), and solved order by order. The solution to the leading terms of these expansions yield the asymptotic form of the Killing vector field. The possible classes of Killing fields are discussed by analysing their orbits on null infinity. The integrability conditions of the Killing equations are used to obtain constraints on the components of the Weyl tensor (\Psi_0, \Psi_1, \Psi_2) and on the shear (\sigma). The behaviour of the solutions to the constraint equations is studied. It is shown that for Killing fields that are non-supertranslational the characteristics of the constraint equations are the orbits of the restriction of the Killing field to null infinity. As an application, boost-rotation symmetric spacetimes are considered. The constraints on \Psi_0 are used to study the behaviour of the coefficients that give rise to the Newman-Penrose constants, if the spacetime is non-polyhomogeneous, or the logarithmic Newman-Penrose constants if the spacetime is polyhomogeneous. |
0712.1988 | Shahar Hod | Shahar Hod | Bounds on the mass-to-radius ratio for non-compact field configurations | 4 pages | Class.Quant.Grav.24:6019-6024,2007 | 10.1088/0264-9381/24/23/021 | null | gr-qc | null | It is well known that a spherically symmetric compact star whose energy
density decreases monotonically possesses an upper bound on its mass-to-radius
ratio, $2M/R\leq 8/9$. However, field configurations typically will not be
compact. Here we investigate non-compact static configurations whose matter
fields have a slow global spatial decay, bounded by a power law behavior. These
matter distributions have no sharp boundaries. We derive an upper bound on the
fundamental ratio max_r{2m(r)/r} which is valid throughout the bulk. In its
simplest form, the bound implies that in any region of spacetime in which the
radial pressure increases, or alternatively decreases not faster than some
power law $r^{-(c+4)}$, one has $2m(r)/r \leq (2+2c)/(3+2c)$. [For $c \leq 0$
the bound degenerates to $2m(r)/r \leq 2/3$.] In its general version, the bound
is expressed in terms of two physical parameters: the spatial decaying rate of
the matter fields, and the highest occurring ratio of the trace of the pressure
tensor to the local energy density.
| [
{
"created": "Wed, 12 Dec 2007 17:40:54 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Hod",
"Shahar",
""
]
] | It is well known that a spherically symmetric compact star whose energy density decreases monotonically possesses an upper bound on its mass-to-radius ratio, $2M/R\leq 8/9$. However, field configurations typically will not be compact. Here we investigate non-compact static configurations whose matter fields have a slow global spatial decay, bounded by a power law behavior. These matter distributions have no sharp boundaries. We derive an upper bound on the fundamental ratio max_r{2m(r)/r} which is valid throughout the bulk. In its simplest form, the bound implies that in any region of spacetime in which the radial pressure increases, or alternatively decreases not faster than some power law $r^{-(c+4)}$, one has $2m(r)/r \leq (2+2c)/(3+2c)$. [For $c \leq 0$ the bound degenerates to $2m(r)/r \leq 2/3$.] In its general version, the bound is expressed in terms of two physical parameters: the spatial decaying rate of the matter fields, and the highest occurring ratio of the trace of the pressure tensor to the local energy density. |
0810.0006 | Thomas W. Baumgarte | T. W. Baumgarte, Z. B. Etienne, Y. T. Liu, K. Matera, N. \'O
Murchadha, S. L. Shapiro and K. Taniguchi | Equilibrium initial data for moving puncture simulations: The stationary
1+log slicing | 20 pages, 3 figures, published version | Class.Quant.Grav.26:085007,2009 | 10.1088/0264-9381/26/8/085007 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose and explore a "stationary 1+log" slicing condition for the
construction of solutions to Einstein's constraint equations. For stationary
spacetimes, these initial data will give a stationary foliation when evolved
with "moving puncture" gauge conditions that are often used in black hole
evolutions. The resulting slicing is time-independent and agrees with the
slicing generated by being dragged along a time-like Killing vector of the
spacetime. When these initial data are evolved with moving puncture gauge
conditions, numerical errors arising from coordinate evolution are minimized.
In the construction of initial data for binary black holes it is often assumed
that there exists an approximate helical Killing vector that generates the
binary's orbit. We show that, unfortunately, 1+log slices that are stationary
with respect to such a helical Killing vector cannot be asymptotically flat,
unless the spacetime possesses an additional axial Killing vector.
| [
{
"created": "Tue, 30 Sep 2008 20:01:41 GMT",
"version": "v1"
},
{
"created": "Thu, 1 Oct 2009 21:26:58 GMT",
"version": "v2"
}
] | 2009-10-12 | [
[
"Baumgarte",
"T. W.",
""
],
[
"Etienne",
"Z. B.",
""
],
[
"Liu",
"Y. T.",
""
],
[
"Matera",
"K.",
""
],
[
"Murchadha",
"N. Ó",
""
],
[
"Shapiro",
"S. L.",
""
],
[
"Taniguchi",
"K.",
""
]
] | We propose and explore a "stationary 1+log" slicing condition for the construction of solutions to Einstein's constraint equations. For stationary spacetimes, these initial data will give a stationary foliation when evolved with "moving puncture" gauge conditions that are often used in black hole evolutions. The resulting slicing is time-independent and agrees with the slicing generated by being dragged along a time-like Killing vector of the spacetime. When these initial data are evolved with moving puncture gauge conditions, numerical errors arising from coordinate evolution are minimized. In the construction of initial data for binary black holes it is often assumed that there exists an approximate helical Killing vector that generates the binary's orbit. We show that, unfortunately, 1+log slices that are stationary with respect to such a helical Killing vector cannot be asymptotically flat, unless the spacetime possesses an additional axial Killing vector. |
gr-qc/9906053 | David Garfinkle | David Garfinkle | Metrics with distributional curvature | 7 pages, Revtex, terminology changed, background material added | Class.Quant.Grav. 16 (1999) 4101-4109 | 10.1088/0264-9381/16/12/324 | null | gr-qc | null | This paper considers metrics whose curvature tensor makes sense as a
distribution. A class of such metrics, the regular metrics, was defined and
studied by Geroch and Traschen. Here, we generalize their definition to form a
wider class: semi-regular metrics. We then examine in detail two metrics that
are semi-regular but not regular: (i) Minkowski spacetime minus a wedge and
(ii) a certain traveling wave metric.
| [
{
"created": "Tue, 15 Jun 1999 15:41:12 GMT",
"version": "v1"
},
{
"created": "Thu, 17 Jun 1999 13:15:57 GMT",
"version": "v2"
},
{
"created": "Fri, 18 Jun 1999 12:59:48 GMT",
"version": "v3"
},
{
"created": "Thu, 24 Jun 1999 14:19:27 GMT",
"version": "v4"
},
{
"created": "Thu, 28 Oct 1999 21:24:33 GMT",
"version": "v5"
},
{
"created": "Thu, 28 Oct 1999 23:26:45 GMT",
"version": "v6"
}
] | 2009-10-31 | [
[
"Garfinkle",
"David",
""
]
] | This paper considers metrics whose curvature tensor makes sense as a distribution. A class of such metrics, the regular metrics, was defined and studied by Geroch and Traschen. Here, we generalize their definition to form a wider class: semi-regular metrics. We then examine in detail two metrics that are semi-regular but not regular: (i) Minkowski spacetime minus a wedge and (ii) a certain traveling wave metric. |
gr-qc/0205122 | Alessandra Buonanno | Alessandra Buonanno, Yanbei Chen and Michele Vallisneri | Detection template families for gravitational waves from the final
stages of binary--black-hole inspirals: Nonspinning case | 58 pages, 38 EPS figures, final PRD version; small corrections to GW
flux terms as per Blanchet et al., PRD 71, 129902(E)-129904(E) (2005) | Phys.Rev.D67:024016,2003; Erratum-ibid.D74:029903,2006 | 10.1103/PhysRevD.67.024016 10.1103/PhysRevD.74.029903 | null | gr-qc | null | We investigate the problem of detecting gravitational waves from binaries of
nonspinning black holes with masses m = 5--20 Msun, moving on quasicircular
orbits, which are arguably the most promising sources for first-generation
ground-based detectors. We analyze and compare all the currently available
post--Newtonian approximations for the relativistic two-body dynamics; for
these binaries, different approximations predict different waveforms. We then
construct examples of detection template families that embed all the
approximate models, and that could be used to detect the true
gravitational-wave signal (but not to characterize accurately its physical
parameters). We estimate that the fitting factor for our detection families is
>~0.95 (corresponding to an event-rate loss <~15%) and we estimate that the
discretization of the template family, for ~10^4 templates, increases the loss
to <~20%.
| [
{
"created": "Wed, 29 May 2002 18:26:00 GMT",
"version": "v1"
},
{
"created": "Thu, 12 Dec 2002 01:55:31 GMT",
"version": "v2"
},
{
"created": "Wed, 26 Jul 2006 15:25:45 GMT",
"version": "v3"
}
] | 2014-11-17 | [
[
"Buonanno",
"Alessandra",
""
],
[
"Chen",
"Yanbei",
""
],
[
"Vallisneri",
"Michele",
""
]
] | We investigate the problem of detecting gravitational waves from binaries of nonspinning black holes with masses m = 5--20 Msun, moving on quasicircular orbits, which are arguably the most promising sources for first-generation ground-based detectors. We analyze and compare all the currently available post--Newtonian approximations for the relativistic two-body dynamics; for these binaries, different approximations predict different waveforms. We then construct examples of detection template families that embed all the approximate models, and that could be used to detect the true gravitational-wave signal (but not to characterize accurately its physical parameters). We estimate that the fitting factor for our detection families is >~0.95 (corresponding to an event-rate loss <~15%) and we estimate that the discretization of the template family, for ~10^4 templates, increases the loss to <~20%. |
gr-qc/9711058 | Shin'ji Mukouyama | Shinji Mukohyama | Excitation of a Kaluza-Klein mode by parametric resonance | 36 pages, Latex file, Accepted for publication in Physical Review D | Phys.Rev. D57 (1998) 6191-6205 | 10.1103/PhysRevD.57.6191 | YITP-97-59 | gr-qc astro-ph | null | In this paper we investigate a parametric resonance phenomenon of a
Kaluza-Klein mode in a $D$-dimensional generalized Kaluza-Klein theory. As the
origin of the parametric resonance we consider a small oscillation of a scale
of the compactification around a today's value of it. To make our arguments
definite and for simplicity we consider two classes of models of the
compactification: those by $S_{d}$ ($d=D-4$) and those by $S_{d_{1}}\times
S_{d_{2}}$ ($d_1\ge d_2$, $d_{1}+d_{2}=D-4$). For these models we show that
parametric resonance can occur for the Kaluza-Klein mode. After that, we give
formulas of a creation rate and a number of created quanta of the Kaluza-Klein
mode due to the parametric resonance, taking into account the first and the
second resonance band. By using the formulas we calculate those quantities for
each model of the compactification. Finally we give conditions for the
parametric resonance to be efficient and discuss cosmological implications.
| [
{
"created": "Thu, 20 Nov 1997 02:18:13 GMT",
"version": "v1"
},
{
"created": "Mon, 2 Mar 1998 11:05:38 GMT",
"version": "v2"
}
] | 2009-10-30 | [
[
"Mukohyama",
"Shinji",
""
]
] | In this paper we investigate a parametric resonance phenomenon of a Kaluza-Klein mode in a $D$-dimensional generalized Kaluza-Klein theory. As the origin of the parametric resonance we consider a small oscillation of a scale of the compactification around a today's value of it. To make our arguments definite and for simplicity we consider two classes of models of the compactification: those by $S_{d}$ ($d=D-4$) and those by $S_{d_{1}}\times S_{d_{2}}$ ($d_1\ge d_2$, $d_{1}+d_{2}=D-4$). For these models we show that parametric resonance can occur for the Kaluza-Klein mode. After that, we give formulas of a creation rate and a number of created quanta of the Kaluza-Klein mode due to the parametric resonance, taking into account the first and the second resonance band. By using the formulas we calculate those quantities for each model of the compactification. Finally we give conditions for the parametric resonance to be efficient and discuss cosmological implications. |
gr-qc/9901085 | Wang Bin | Bin Wang and Ru-Keng Su | Entropy, topology of two-dimensional extreme black holes | 16 pages, Latex, accepted for publication on PRD | Phys.Rev.D59:104006,1999 | 10.1103/PhysRevD.59.104006 | null | gr-qc | null | Through direct thermodynamic calculations we have shown that different
classical entropies of two-dimensional extreme black holes appear due to two
different treatments, namely Hawking's treatment and Zaslavskii's treatment.
Geometrical and topological properties corresponding to these different
treatments are investigated. Quantum entropies of the scalar fields on the
backgrounds of these black holes concerning different treatments are also
exhibited. Different results of entropy and geometry lead us to argue that
there are two kinds of extreme black holes in the nature. Explanation of black
hole phase transition has also been given from the quantum point of view.
| [
{
"created": "Fri, 29 Jan 1999 11:58:24 GMT",
"version": "v1"
}
] | 2010-11-22 | [
[
"Wang",
"Bin",
""
],
[
"Su",
"Ru-Keng",
""
]
] | Through direct thermodynamic calculations we have shown that different classical entropies of two-dimensional extreme black holes appear due to two different treatments, namely Hawking's treatment and Zaslavskii's treatment. Geometrical and topological properties corresponding to these different treatments are investigated. Quantum entropies of the scalar fields on the backgrounds of these black holes concerning different treatments are also exhibited. Different results of entropy and geometry lead us to argue that there are two kinds of extreme black holes in the nature. Explanation of black hole phase transition has also been given from the quantum point of view. |
2202.04188 | Job Furtado Neto | M. Nilton, J. Furtado, G. Alencar | On the traversability of wormhole solutions in asymptotically safe
gravity | 12 pages, 10 figures. Two figures included. Matches version accepted
in Phys. Rev. D | null | 10.1103/PhysRevD.105.084048 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | In this paper we study the traversability of a wormhole in the context of
Asymptotically Safe Gravity (ASG) for two different cases, namely, the
spherical case and the pseudospherical case. We carried out an analysis in the
throat of the wormhole with an specific choice of the cutoff function $f=\xi
R$. Recently, this study has been performed in Ref \cite{Moti:2020whf}, however
the authors consider only a classical source with constant state parameter
$\omega$. Here we have generalized their study in two ways: a) with a classical
state parameter which is dependent of the position $\omega(r)$ and b) with an
ASG improvement of the source. We have showed that it is possible to have
traversability with exotic and non-exotic matter, but the kind of matter is
highly dependent on the wormhole's parameters.
| [
{
"created": "Tue, 8 Feb 2022 23:06:47 GMT",
"version": "v1"
},
{
"created": "Sat, 2 Apr 2022 16:57:37 GMT",
"version": "v2"
}
] | 2022-04-28 | [
[
"Nilton",
"M.",
""
],
[
"Furtado",
"J.",
""
],
[
"Alencar",
"G.",
""
]
] | In this paper we study the traversability of a wormhole in the context of Asymptotically Safe Gravity (ASG) for two different cases, namely, the spherical case and the pseudospherical case. We carried out an analysis in the throat of the wormhole with an specific choice of the cutoff function $f=\xi R$. Recently, this study has been performed in Ref \cite{Moti:2020whf}, however the authors consider only a classical source with constant state parameter $\omega$. Here we have generalized their study in two ways: a) with a classical state parameter which is dependent of the position $\omega(r)$ and b) with an ASG improvement of the source. We have showed that it is possible to have traversability with exotic and non-exotic matter, but the kind of matter is highly dependent on the wormhole's parameters. |
1505.05278 | David Brizuela | David Brizuela | A generalization of the Zerilli master variable for a dynamical
spherical spacetime | 14 pages, accepted for publication in Classical and Quantum Gravity | Class. Quant. Grav. 32, 135005 (2015) | 10.1088/0264-9381/32/13/135005 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The evolution of polar perturbations on a spherical background spacetime is
analyzed. The matter content is assumed to be a massless scalar field.This
provides a nontrivial dynamics to the background and the linearized equations
of motion become much more involved than in the vacuum case. The analysis is
performed in a Hamiltonian framework, which makes explicit the dynamical role
of each of the variables. After performing a number of canonical
transformations, it is possible to completely decouple the different
perturbative degrees of freedom into constrained, pure-gauge and
gauge-invariant variables. In particular, two master variables are obtained:
one corresponding to the polar mode of the gravitational wave, whereas the
other encodes the complete physical information about the perturbative matter
degree of freedom. The evolution equations for these master variables are
obtained and simplified.
| [
{
"created": "Wed, 20 May 2015 08:28:23 GMT",
"version": "v1"
}
] | 2022-01-28 | [
[
"Brizuela",
"David",
""
]
] | The evolution of polar perturbations on a spherical background spacetime is analyzed. The matter content is assumed to be a massless scalar field.This provides a nontrivial dynamics to the background and the linearized equations of motion become much more involved than in the vacuum case. The analysis is performed in a Hamiltonian framework, which makes explicit the dynamical role of each of the variables. After performing a number of canonical transformations, it is possible to completely decouple the different perturbative degrees of freedom into constrained, pure-gauge and gauge-invariant variables. In particular, two master variables are obtained: one corresponding to the polar mode of the gravitational wave, whereas the other encodes the complete physical information about the perturbative matter degree of freedom. The evolution equations for these master variables are obtained and simplified. |
1005.3310 | Nicolas Yunes | Nicolas Yunes, Richard O'Shaughnessy, Benjamin J. Owen and Stephon
Alexander | Testing gravitational parity violation with coincident gravitational
waves and short gamma-ray bursts | 21 pages, 2 figures, submitted to Phys. Rev. D | Phys.Rev.D82:064017,2010 | 10.1103/PhysRevD.82.064017 | IGC-10/5-2 | gr-qc astro-ph.CO astro-ph.HE hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational parity violation is a possibility motivated by particle
physics, string theory and loop quantum gravity. One effect of it is amplitude
birefringence of gravitational waves, whereby left and right
circularly-polarized waves propagate at the same speed but with different
amplitude evolution. Here we propose a test of this effect through coincident
observations of gravitational waves and short gamma-ray bursts from binary
mergers involving neutron stars. Such gravitational waves are highly left or
right circularly-polarized due to the geometry of the merger. Using
localization information from the gamma-ray burst, ground-based gravitational
wave detectors can measure the distance to the source with reasonable accuracy.
An electromagnetic determination of the redshift from an afterglow or host
galaxy yields an independent measure of this distance. Gravitational parity
violation would manifest itself as a discrepancy between these two distance
measurements. We exemplify such a test by considering one specific effective
theory that leads to such gravitational parity-violation, Chern-Simons gravity.
We show that the advanced LIGO-Virgo network and all-sky gamma-ray telescopes
can be sensitive to the propagating sector of Chern-Simons gravitational parity
violation to a level roughly two orders of magnitude better than current
stationary constraints from the LAGEOS satellites.
| [
{
"created": "Tue, 18 May 2010 20:02:00 GMT",
"version": "v1"
}
] | 2011-05-04 | [
[
"Yunes",
"Nicolas",
""
],
[
"O'Shaughnessy",
"Richard",
""
],
[
"Owen",
"Benjamin J.",
""
],
[
"Alexander",
"Stephon",
""
]
] | Gravitational parity violation is a possibility motivated by particle physics, string theory and loop quantum gravity. One effect of it is amplitude birefringence of gravitational waves, whereby left and right circularly-polarized waves propagate at the same speed but with different amplitude evolution. Here we propose a test of this effect through coincident observations of gravitational waves and short gamma-ray bursts from binary mergers involving neutron stars. Such gravitational waves are highly left or right circularly-polarized due to the geometry of the merger. Using localization information from the gamma-ray burst, ground-based gravitational wave detectors can measure the distance to the source with reasonable accuracy. An electromagnetic determination of the redshift from an afterglow or host galaxy yields an independent measure of this distance. Gravitational parity violation would manifest itself as a discrepancy between these two distance measurements. We exemplify such a test by considering one specific effective theory that leads to such gravitational parity-violation, Chern-Simons gravity. We show that the advanced LIGO-Virgo network and all-sky gamma-ray telescopes can be sensitive to the propagating sector of Chern-Simons gravitational parity violation to a level roughly two orders of magnitude better than current stationary constraints from the LAGEOS satellites. |
0901.2722 | Bruno Giacomazzo | Bruno Giacomazzo, Luciano Rezzolla, Luca Baiotti | Can magnetic fields be detected during the inspiral of binary neutron
stars? | 5 pages, 4 figures. Small changes to text and figures. Matches
version to appear on MNRAS Letters | Mon.Not.Roy.Astron.Soc.399:L164-L168,2009 | 10.1111/j.1745-3933.2009.00745.x | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using accurate and fully general-relativistic simulations we assess the
effect that magnetic fields have on the gravitational-wave emission produced
during the inspiral and merger of magnetized neutron stars. In particular, we
show that magnetic fields have an impact after the merger, because they are
amplified by a Kelvin-Helmholtz instability, but also during the inspiral, most
likely because the magnetic tension reduces the stellar tidal deformation for
extremely large initial magnetic fields, B_0>~10^{17}G. We quantify the
influence of magnetic fields by computing the overlap, O, between the waveforms
produced during the inspiral by magnetized and unmagnetized binaries. We find
that for any realistic magnetic field strength B_0<~10^{14}G the overlap during
the inspiral is O>~0.999 and is quite insensitive to the mass of the neutron
stars. Only for unrealistically large magnetic fields like B_0~10^{17}G the
overlap does decrease noticeably, becoming at our resolutions O<~0.76/0.67 for
stars with baryon masses M_b~1.4/1.6 Msun, respectively. Because neutron stars
are expected to merge with magnetic fields ~10^{8}-10^{10}G and because present
detectors are sensitive to O<~0.995, we conclude that it is very unlikely that
the present detectors will be able to discern the presence of magnetic fields
during the inspiral of neutron stars.
| [
{
"created": "Sun, 18 Jan 2009 20:51:31 GMT",
"version": "v1"
},
{
"created": "Mon, 7 Sep 2009 11:29:33 GMT",
"version": "v2"
}
] | 2009-10-12 | [
[
"Giacomazzo",
"Bruno",
""
],
[
"Rezzolla",
"Luciano",
""
],
[
"Baiotti",
"Luca",
""
]
] | Using accurate and fully general-relativistic simulations we assess the effect that magnetic fields have on the gravitational-wave emission produced during the inspiral and merger of magnetized neutron stars. In particular, we show that magnetic fields have an impact after the merger, because they are amplified by a Kelvin-Helmholtz instability, but also during the inspiral, most likely because the magnetic tension reduces the stellar tidal deformation for extremely large initial magnetic fields, B_0>~10^{17}G. We quantify the influence of magnetic fields by computing the overlap, O, between the waveforms produced during the inspiral by magnetized and unmagnetized binaries. We find that for any realistic magnetic field strength B_0<~10^{14}G the overlap during the inspiral is O>~0.999 and is quite insensitive to the mass of the neutron stars. Only for unrealistically large magnetic fields like B_0~10^{17}G the overlap does decrease noticeably, becoming at our resolutions O<~0.76/0.67 for stars with baryon masses M_b~1.4/1.6 Msun, respectively. Because neutron stars are expected to merge with magnetic fields ~10^{8}-10^{10}G and because present detectors are sensitive to O<~0.995, we conclude that it is very unlikely that the present detectors will be able to discern the presence of magnetic fields during the inspiral of neutron stars. |
1804.01072 | Thiago R.P. Caram\^es | J. C. Fabris, Thiago R. P. Caram\^es and J. M. Hoff da Silva | Braneworld gravity within non-conservative gravitational theory | 7 pages | Eur. Phys. J. C (2018) 78: 402 | 10.1140/epjc/s10052-018-5891-0 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the braneworld gravity starting from the non-conservative
gravitational field equations in a five-dimensional bulk. The approach is based
on the Gauss-Codazzi formalism along with the study of the braneworld
consistency conditions. The effective gravitational equations on the brane are
obtained and the constraint leading to a brane energy-momentum conservation is
analyzed.
| [
{
"created": "Tue, 3 Apr 2018 17:37:03 GMT",
"version": "v1"
}
] | 2018-05-28 | [
[
"Fabris",
"J. C.",
""
],
[
"Caramês",
"Thiago R. P.",
""
],
[
"da Silva",
"J. M. Hoff",
""
]
] | We investigate the braneworld gravity starting from the non-conservative gravitational field equations in a five-dimensional bulk. The approach is based on the Gauss-Codazzi formalism along with the study of the braneworld consistency conditions. The effective gravitational equations on the brane are obtained and the constraint leading to a brane energy-momentum conservation is analyzed. |
2403.03487 | Tousif Islam | Tousif Islam | Study of eccentric binary black hole mergers using numerical relativity
and an inspiral-merger-ringdown model | 22 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the phenomenology of non-spinning eccentric binary black hole (BBH)
mergers using numerical relativity (NR) waveforms and \texttt{EccentricIMR}
waveform model, as presented in Ref. \cite{Hinder:2017sxy} (Hinder, Kidder, and
Pfeiffer, arXiv:1709.02007). This model is formulated by combining an eccentric
inspiral, derived from a post-Newtonian (PN) approximation including 3PN
conservative and 2PN reactive contributions to the BBH dynamics, with a
circular merger model. A distinctive feature of \texttt{EccentricIMR} is its
two-parameter treatment, utilizing eccentricity and mean anomaly, to
characterize eccentric waveforms. We implement the \texttt{EccentricIMR} model
in \texttt{Python} to facilitate routine use. We then validate the model
against 35 eccentric NR waveforms obtained from both the SXS and RIT NR
catalogs. We find that \texttt{EccentricIMR} model reasonably match NR data for
eccentricities up to $0.16$, specified at a dimensionless reference frequency
of $x=0.07$, and mass ratios up to $q=4$. Additionally, we use this model as a
tool for cross-comparing eccentric NR data obtained from the SXS and RIT
catalogs. Furthermore, we explore the validity of a circular merger model often
used in eccentric BBH merger modelling using both the NR data and
\texttt{EccentricIMR} model. Finally, we use this model to explore the effect
of mean anomaly in eccentric BBH mergers.
| [
{
"created": "Wed, 6 Mar 2024 06:05:21 GMT",
"version": "v1"
}
] | 2024-03-07 | [
[
"Islam",
"Tousif",
""
]
] | We study the phenomenology of non-spinning eccentric binary black hole (BBH) mergers using numerical relativity (NR) waveforms and \texttt{EccentricIMR} waveform model, as presented in Ref. \cite{Hinder:2017sxy} (Hinder, Kidder, and Pfeiffer, arXiv:1709.02007). This model is formulated by combining an eccentric inspiral, derived from a post-Newtonian (PN) approximation including 3PN conservative and 2PN reactive contributions to the BBH dynamics, with a circular merger model. A distinctive feature of \texttt{EccentricIMR} is its two-parameter treatment, utilizing eccentricity and mean anomaly, to characterize eccentric waveforms. We implement the \texttt{EccentricIMR} model in \texttt{Python} to facilitate routine use. We then validate the model against 35 eccentric NR waveforms obtained from both the SXS and RIT NR catalogs. We find that \texttt{EccentricIMR} model reasonably match NR data for eccentricities up to $0.16$, specified at a dimensionless reference frequency of $x=0.07$, and mass ratios up to $q=4$. Additionally, we use this model as a tool for cross-comparing eccentric NR data obtained from the SXS and RIT catalogs. Furthermore, we explore the validity of a circular merger model often used in eccentric BBH merger modelling using both the NR data and \texttt{EccentricIMR} model. Finally, we use this model to explore the effect of mean anomaly in eccentric BBH mergers. |
1906.01899 | Fabio Moretti | Fabio Moretti, Flavio Bombacigno and Giovanni Montani | Gauge invariant formulation of gravitational waves in metric $f(R)$
gravity | 6 pages, no figures. Comments are welcome | Phys. Rev. D 100, 084014 (2019) | 10.1103/PhysRevD.100.084014 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyze the gravitational waves propagation in metric $f(R)$ theories of
gravity. In particular, adopting a gauge invariant formalism we clearly
determine the exact propagating degrees of freedom. Then, investigating their
effects on test masses via geodesic deviation equation, we show that the
additional dynamical degree contained in such extended formulations is actually
responsible for two distinguished polarizations, corresponding to a breathing
and a longitudinal mode, respectively.
| [
{
"created": "Wed, 5 Jun 2019 09:20:13 GMT",
"version": "v1"
},
{
"created": "Wed, 25 Sep 2019 14:37:16 GMT",
"version": "v2"
}
] | 2019-10-11 | [
[
"Moretti",
"Fabio",
""
],
[
"Bombacigno",
"Flavio",
""
],
[
"Montani",
"Giovanni",
""
]
] | We analyze the gravitational waves propagation in metric $f(R)$ theories of gravity. In particular, adopting a gauge invariant formalism we clearly determine the exact propagating degrees of freedom. Then, investigating their effects on test masses via geodesic deviation equation, we show that the additional dynamical degree contained in such extended formulations is actually responsible for two distinguished polarizations, corresponding to a breathing and a longitudinal mode, respectively. |
2007.01968 | Cl\'esio Evangelista Mota | Cl\'esio E. Mota, Luis C. N. Santos, Franciele M. da Silva, Guilherme
Grams, Iarley P. Lobo, D\'ebora P. Menezes | Generalized Rastall's gravity and its effects on compact objects | null | null | 10.1142/S0218271822500237 | null | gr-qc astro-ph.HE nucl-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a generalization of Rastall's gravity in which the conservation
law of the energy-momentum tensor is altered, and as a result, the trace of the
energy-momentum tensor is taken into account together with the Ricci scalar in
the expression for the covariant derivative. Afterwards, we obtain the field
equations in this theory and solve them by considering a spherically symmetric
space-time. We show that the external solution has two possible classes of
solutions with spherical symmetry in the vacuum in generalized Rastall's
gravity, and we analyse one of them explicitly. The generalization, in contrast
to constant value $k=8\pi G$ in general relativity, has a gravitational
parameter $k$ that depends on the Rastall constant $\alpha$. As an application,
we perform a careful analysis of the effects of the theory on neutron stars
using realistic equations of state (EoS) as input. Our results show that
important differences on the profile of neutron stars are obtained within two
representatives EoS.
| [
{
"created": "Fri, 3 Jul 2020 23:39:20 GMT",
"version": "v1"
},
{
"created": "Fri, 16 Oct 2020 13:37:25 GMT",
"version": "v2"
},
{
"created": "Wed, 23 Feb 2022 15:34:48 GMT",
"version": "v3"
}
] | 2022-02-24 | [
[
"Mota",
"Clésio E.",
""
],
[
"Santos",
"Luis C. N.",
""
],
[
"da Silva",
"Franciele M.",
""
],
[
"Grams",
"Guilherme",
""
],
[
"Lobo",
"Iarley P.",
""
],
[
"Menezes",
"Débora P.",
""
]
] | We present a generalization of Rastall's gravity in which the conservation law of the energy-momentum tensor is altered, and as a result, the trace of the energy-momentum tensor is taken into account together with the Ricci scalar in the expression for the covariant derivative. Afterwards, we obtain the field equations in this theory and solve them by considering a spherically symmetric space-time. We show that the external solution has two possible classes of solutions with spherical symmetry in the vacuum in generalized Rastall's gravity, and we analyse one of them explicitly. The generalization, in contrast to constant value $k=8\pi G$ in general relativity, has a gravitational parameter $k$ that depends on the Rastall constant $\alpha$. As an application, we perform a careful analysis of the effects of the theory on neutron stars using realistic equations of state (EoS) as input. Our results show that important differences on the profile of neutron stars are obtained within two representatives EoS. |
gr-qc/0602107 | Elias C. Vagenas | Elias C. Vagenas | Energy distribution in the dyadosphere of a Reissner-Nordstrom black
hole in Moller's prescription | 12 pages, no figure, LaTeX | Mod.Phys.Lett.A21:1947-1956,2006 | 10.1142/S0217732306020482 | null | gr-qc astro-ph hep-th | null | The energy and momentum distributions in the dyadosphere of a
Reissner-Nordstrom black hole are evaluated. The Moller's energy-momentum
complex is employed for this computation. The spacetime under study is modified
due to the effects of vacuum fluctuations in the dyadosphere. Therefore, the
corrected Reissner-Nordstrom black hole metric takes into account the first
contribution of the weak field limit of one-loop QED. Furthermore, a comparison
and a consequent connection between our results that those already existing in
the literature is provided. We hypothesize that when the energy distribution is
of specific form there is a relation that connects the coefficients in the
Einstein's prescription with those in the Moller's prescription.
| [
{
"created": "Sun, 26 Feb 2006 16:29:52 GMT",
"version": "v1"
},
{
"created": "Wed, 22 Mar 2006 19:30:16 GMT",
"version": "v2"
}
] | 2010-11-11 | [
[
"Vagenas",
"Elias C.",
""
]
] | The energy and momentum distributions in the dyadosphere of a Reissner-Nordstrom black hole are evaluated. The Moller's energy-momentum complex is employed for this computation. The spacetime under study is modified due to the effects of vacuum fluctuations in the dyadosphere. Therefore, the corrected Reissner-Nordstrom black hole metric takes into account the first contribution of the weak field limit of one-loop QED. Furthermore, a comparison and a consequent connection between our results that those already existing in the literature is provided. We hypothesize that when the energy distribution is of specific form there is a relation that connects the coefficients in the Einstein's prescription with those in the Moller's prescription. |
2003.07145 | Johannes Bl\"umlein | J. Bl\"umlein, A. Maier, P. Marquard, and G. Sch\"afer | Testing binary dynamics in gravity at the sixth post-Newtonian level | 13 pages Latex | null | 10.1016/j.physletb.2020.135496 | DESY 20--044, DO--TH 20/02, SAGEX--20--06 | gr-qc astro-ph.SR hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We calculate the motion of binary mass systems in gravity up to the sixth
post--Newtonian order to the $G_N^3$ terms ab initio using momentum expansions
within an effective field theory approach based on Feynman amplitudes in
harmonic coordinates. For these contributions we construct a canonical
transformation to isotropic and to EOB coordinates at 5PN and agree with the
results in the literature \cite{Bern:2019nnu,Damour:2019lcq}. At 6PN we compare
to the Hamiltonians in isotropic coordinates either given in
\cite{Bern:2019nnu} or resulting from the scattering angle. We find a canonical
transformation from our Hamiltonian in harmonic coordinates to
\cite{Bern:2019nnu}, but not to \cite{Damour:2019lcq}. This implies that we
also agree on all observables with \cite{Bern:2019nnu} to the sixth
post--Newtonian order to $G_N^3$.
| [
{
"created": "Mon, 16 Mar 2020 12:30:50 GMT",
"version": "v1"
}
] | 2020-07-15 | [
[
"Blümlein",
"J.",
""
],
[
"Maier",
"A.",
""
],
[
"Marquard",
"P.",
""
],
[
"Schäfer",
"G.",
""
]
] | We calculate the motion of binary mass systems in gravity up to the sixth post--Newtonian order to the $G_N^3$ terms ab initio using momentum expansions within an effective field theory approach based on Feynman amplitudes in harmonic coordinates. For these contributions we construct a canonical transformation to isotropic and to EOB coordinates at 5PN and agree with the results in the literature \cite{Bern:2019nnu,Damour:2019lcq}. At 6PN we compare to the Hamiltonians in isotropic coordinates either given in \cite{Bern:2019nnu} or resulting from the scattering angle. We find a canonical transformation from our Hamiltonian in harmonic coordinates to \cite{Bern:2019nnu}, but not to \cite{Damour:2019lcq}. This implies that we also agree on all observables with \cite{Bern:2019nnu} to the sixth post--Newtonian order to $G_N^3$. |
2112.15441 | Francesco Sorge | Francesco Sorge | Kerr spacetime in Lema\^itre coordinates | 19 pages, 3 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a novel formulation of the Kerr spacetime solution, based on the
Lema\^itre coordinates. Such an approach allows one to avoid the coordinate
singularities of the Boyer-Lindquist metric, thus offering the possibility to
explore in some detail the Kerr physics near and beyond the event horizon,
adopting the point of view of a freely falling observer, whose adapted tetrad
is moreover proven to be Fermi-Walker transported. We use the Lema\^itre form
of the Kerr metric discussing the motion of radial photons close to the Cauchy
horizon, also showing that their behaviour fairly agrees with other similar
results presented in the literature. Being synchronous, the Lema\^itre form of
the Kerr metric allows a Hamiltonian formulation of a quantum field theory
nearby and beyond the Kerr event horizon. This could provide a further tool in
the investigation of the intriguing issue concerning the Cauchy horizon
(in)stability.
| [
{
"created": "Tue, 28 Dec 2021 11:07:07 GMT",
"version": "v1"
}
] | 2022-01-03 | [
[
"Sorge",
"Francesco",
""
]
] | We present a novel formulation of the Kerr spacetime solution, based on the Lema\^itre coordinates. Such an approach allows one to avoid the coordinate singularities of the Boyer-Lindquist metric, thus offering the possibility to explore in some detail the Kerr physics near and beyond the event horizon, adopting the point of view of a freely falling observer, whose adapted tetrad is moreover proven to be Fermi-Walker transported. We use the Lema\^itre form of the Kerr metric discussing the motion of radial photons close to the Cauchy horizon, also showing that their behaviour fairly agrees with other similar results presented in the literature. Being synchronous, the Lema\^itre form of the Kerr metric allows a Hamiltonian formulation of a quantum field theory nearby and beyond the Kerr event horizon. This could provide a further tool in the investigation of the intriguing issue concerning the Cauchy horizon (in)stability. |
2311.00245 | Susanne Schander | Thorsten Lang and Susanne Schander | Gauge Symmetry Breaking Lattice Regularizations and their Continuum
Limit | null | null | null | null | gr-qc hep-lat math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Lattice regularizations are pivotal in the non-perturbative quantization of
gauge field theories. Wilson's proposal to employ group-valued link fields
simplifies the regularization of gauge fields in principal fiber bundles,
preserving gauge symmetry within the discretized lattice theory. Maintaining
gauge symmetry is desirable as its violation can introduce unwanted degrees of
freedom. However, not all theories with gauge symmetries admit gauge-invariant
lattice regularizations, as observed in general relativity where the
diffeomorphism group serves as the gauge symmetry. In such cases, gauge
symmetry-breaking regularizations become necessary. In this paper, we argue
that a broken lattice gauge symmetry is acceptable as long as gauge symmetry is
restored in the continuum limit. We propose a method to construct the continuum
limit for a class of lattice-regularized Hamiltonian field theories, where the
regularization breaks the Lie algebra of first-class constraints. Additionally,
we offer an approach to represent the exact gauge group on the Hilbert space of
the continuum theory. The considered class of theories is limited to those with
first-class constraints linear in momenta, excluding the entire gauge group of
general relativity but encompassing its subgroup of spatial diffeomorphisms. We
discuss potential techniques for extending this quantization to the full gauge
group.
| [
{
"created": "Wed, 1 Nov 2023 02:59:25 GMT",
"version": "v1"
}
] | 2023-11-02 | [
[
"Lang",
"Thorsten",
""
],
[
"Schander",
"Susanne",
""
]
] | Lattice regularizations are pivotal in the non-perturbative quantization of gauge field theories. Wilson's proposal to employ group-valued link fields simplifies the regularization of gauge fields in principal fiber bundles, preserving gauge symmetry within the discretized lattice theory. Maintaining gauge symmetry is desirable as its violation can introduce unwanted degrees of freedom. However, not all theories with gauge symmetries admit gauge-invariant lattice regularizations, as observed in general relativity where the diffeomorphism group serves as the gauge symmetry. In such cases, gauge symmetry-breaking regularizations become necessary. In this paper, we argue that a broken lattice gauge symmetry is acceptable as long as gauge symmetry is restored in the continuum limit. We propose a method to construct the continuum limit for a class of lattice-regularized Hamiltonian field theories, where the regularization breaks the Lie algebra of first-class constraints. Additionally, we offer an approach to represent the exact gauge group on the Hilbert space of the continuum theory. The considered class of theories is limited to those with first-class constraints linear in momenta, excluding the entire gauge group of general relativity but encompassing its subgroup of spatial diffeomorphisms. We discuss potential techniques for extending this quantization to the full gauge group. |
1209.0465 | Paolo Pani | Paolo Pani, Vitor Cardoso, Leonardo Gualtieri, Emanuele Berti, Akihiro
Ishibashi | Black-Hole Bombs and Photon-Mass Bounds | 5 pages, 2 figures. References added. Matches published version | null | 10.1103/PhysRevLett.109.131102 | null | gr-qc astro-ph.HE hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Generic extensions of the standard model predict the existence of ultralight
bosonic degrees of freedom. Several ongoing experiments are aimed at detecting
these particles or constraining their mass range. Here we show that massive
vector fields around rotating black holes can give rise to a strong
superradiant instability which extracts angular momentum from the hole. The
observation of supermassive spinning black holes imposes limits on this
mechanism. We show that current supermassive black hole spin estimates provide
the tightest upper limits on the mass of the photon (mv<4x10^{-20} eV according
to our most conservative estimate), and that spin measurements for the largest
known supermassive black holes could further lower this bound to mv<10^{-22}
eV. Our analysis relies on a novel framework to study perturbations of rotating
Kerr black holes in the slow-rotation regime, that we developed up to second
order in rotation, and that can be extended to other spacetime metrics and
other theories.
| [
{
"created": "Mon, 3 Sep 2012 20:00:10 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Sep 2012 06:43:37 GMT",
"version": "v2"
}
] | 2015-06-11 | [
[
"Pani",
"Paolo",
""
],
[
"Cardoso",
"Vitor",
""
],
[
"Gualtieri",
"Leonardo",
""
],
[
"Berti",
"Emanuele",
""
],
[
"Ishibashi",
"Akihiro",
""
]
] | Generic extensions of the standard model predict the existence of ultralight bosonic degrees of freedom. Several ongoing experiments are aimed at detecting these particles or constraining their mass range. Here we show that massive vector fields around rotating black holes can give rise to a strong superradiant instability which extracts angular momentum from the hole. The observation of supermassive spinning black holes imposes limits on this mechanism. We show that current supermassive black hole spin estimates provide the tightest upper limits on the mass of the photon (mv<4x10^{-20} eV according to our most conservative estimate), and that spin measurements for the largest known supermassive black holes could further lower this bound to mv<10^{-22} eV. Our analysis relies on a novel framework to study perturbations of rotating Kerr black holes in the slow-rotation regime, that we developed up to second order in rotation, and that can be extended to other spacetime metrics and other theories. |
2302.03192 | Yen-Kheng Lim PhD | Ian Khai-Shuen Ng, Wei Zheng Choo, and Yen-Kheng Lim | Model for an electrostatic capacitor in Einstein-Maxwell theory | 17 pages, 3 figures. New section about spherical capacitor is added.
A coordinate-independent notion of capacitance is introduced | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A general relativistic model of a parallel-plate electrostatic capacitor is
presented. The spacetime is a solution to the Einstein--Maxwell equations and
involves class of solution previously studied by Vesel\'{y} and \v{Z}ofka
(V\v{Z}). In particular, the parts containing curvature singularities are cut
out and the remaining regular section is glued to asymptotically-Minkowski
spacetimes. In essence, this results in a curved electro-vacuum V\v{Z}
spacetime sandwiched on both sides by exterior spacetimes with vanishing
electromagnetic fields. Junction conditions require the presence of charged
matter on the boundaries. We interpret this configuration as a parallel-plate
capacitor with gravitational effects induced by the strong electric fields. The
spherical capacitor is briefly considered.
| [
{
"created": "Tue, 7 Feb 2023 01:49:11 GMT",
"version": "v1"
},
{
"created": "Fri, 2 Jun 2023 07:43:26 GMT",
"version": "v2"
}
] | 2023-06-05 | [
[
"Ng",
"Ian Khai-Shuen",
""
],
[
"Choo",
"Wei Zheng",
""
],
[
"Lim",
"Yen-Kheng",
""
]
] | A general relativistic model of a parallel-plate electrostatic capacitor is presented. The spacetime is a solution to the Einstein--Maxwell equations and involves class of solution previously studied by Vesel\'{y} and \v{Z}ofka (V\v{Z}). In particular, the parts containing curvature singularities are cut out and the remaining regular section is glued to asymptotically-Minkowski spacetimes. In essence, this results in a curved electro-vacuum V\v{Z} spacetime sandwiched on both sides by exterior spacetimes with vanishing electromagnetic fields. Junction conditions require the presence of charged matter on the boundaries. We interpret this configuration as a parallel-plate capacitor with gravitational effects induced by the strong electric fields. The spherical capacitor is briefly considered. |
2305.15500 | Konstantinos Dialektopoulos F. | Konstantinos F. Dialektopoulos, Purba Mukherjee, Jackson Levi Said,
Jurgen Mifsud | Neural network reconstruction of scalar-tensor cosmology | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Neural networks have shown great promise in providing a data-first approach
to exploring new physics. In this work, we use the full implementation of late
time cosmological data to reconstruct a number of scalar-tensor cosmological
models within the context of neural network systems. In this pipeline, we
incorporate covariances in the data in the neural network training algorithm,
rather than a likelihood which is the approach taken in Markov chain Monte
Carlo analyses. For general subclasses of classic scalar-tensor models, we find
stricter bounds on functional models which may help in the understanding of
which models are observationally viable.
| [
{
"created": "Wed, 24 May 2023 18:42:25 GMT",
"version": "v1"
}
] | 2023-05-26 | [
[
"Dialektopoulos",
"Konstantinos F.",
""
],
[
"Mukherjee",
"Purba",
""
],
[
"Said",
"Jackson Levi",
""
],
[
"Mifsud",
"Jurgen",
""
]
] | Neural networks have shown great promise in providing a data-first approach to exploring new physics. In this work, we use the full implementation of late time cosmological data to reconstruct a number of scalar-tensor cosmological models within the context of neural network systems. In this pipeline, we incorporate covariances in the data in the neural network training algorithm, rather than a likelihood which is the approach taken in Markov chain Monte Carlo analyses. For general subclasses of classic scalar-tensor models, we find stricter bounds on functional models which may help in the understanding of which models are observationally viable. |
1007.2852 | Muhammad Sharif | M. Sharif and H. Rizwana Kausar | Gravitational Perfect Fluid Collapse in f(R) Gravity | 17 pages, accepted for publication in Astrophys. Space Sci | Astrophys. Space Sci.331:281-288, 2011 | 10.1007/s10509-010-0426-7 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we investigate spherically symmetric perfect fluid
gravitational collapse in metric $f(R)$ gravity. We take non-static spherically
symmetric metric in the interior region and static spherically symmetric metric
in the exterior region of a star. The junction conditions between interior and
exterior spacetimes are derived. The field equations in f(R) theory are solved
using the assumption of constant Ricci scalar. Inserting their solution into
junction conditions, the gravitational mass is found. Further, the apparent
horizons and their time of formation is discussed. We conclude that the
constant scalar curvature term f(R_0) acts as a source of repulsive force and
thus slows down the collapse of matter. The comparison with the corresponding
results available in general relativity indicates that f(R_0) plays the role of
the cosmological constant.
| [
{
"created": "Fri, 18 Jun 2010 02:27:48 GMT",
"version": "v1"
}
] | 2011-01-17 | [
[
"Sharif",
"M.",
""
],
[
"Kausar",
"H. Rizwana",
""
]
] | In this paper, we investigate spherically symmetric perfect fluid gravitational collapse in metric $f(R)$ gravity. We take non-static spherically symmetric metric in the interior region and static spherically symmetric metric in the exterior region of a star. The junction conditions between interior and exterior spacetimes are derived. The field equations in f(R) theory are solved using the assumption of constant Ricci scalar. Inserting their solution into junction conditions, the gravitational mass is found. Further, the apparent horizons and their time of formation is discussed. We conclude that the constant scalar curvature term f(R_0) acts as a source of repulsive force and thus slows down the collapse of matter. The comparison with the corresponding results available in general relativity indicates that f(R_0) plays the role of the cosmological constant. |
0910.4256 | Fumitoshi Amemiya | Fumitoshi Amemiya, Tatsuhiko Koike | Gauge-invariant construction of quantum cosmology | 8 pages, 7 figures, accepted for publication in Phys. Rev. D | Phys.Rev.D80:103507,2009 | 10.1103/PhysRevD.80.103507 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present and analyze a gauge-invariant quantum theory of the
Friedmann-Robertson-Walker universe with dust. We construct the reduced phase
space spanned by gauge-invariant quantities by using the so-called relational
formalism at the classical level. The reduced phase space thereby obtained can
be quantized in the same manner as an ordinary mechanical system. We carry out
the quantization and obtain the Schr\"{o}dinger equation. This quantization
procedure realizes a possible resolution to the problem of time and observables
in canonical quantum gravity. We analyze the classical initial singularity of
the theory by evolving a wave packet backward in time and evaluating the
expectation value of the scale factor. It is shown that the initial singularity
of the Universe is avoided by the quantum gravitational effects.
| [
{
"created": "Thu, 22 Oct 2009 18:56:01 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Amemiya",
"Fumitoshi",
""
],
[
"Koike",
"Tatsuhiko",
""
]
] | We present and analyze a gauge-invariant quantum theory of the Friedmann-Robertson-Walker universe with dust. We construct the reduced phase space spanned by gauge-invariant quantities by using the so-called relational formalism at the classical level. The reduced phase space thereby obtained can be quantized in the same manner as an ordinary mechanical system. We carry out the quantization and obtain the Schr\"{o}dinger equation. This quantization procedure realizes a possible resolution to the problem of time and observables in canonical quantum gravity. We analyze the classical initial singularity of the theory by evolving a wave packet backward in time and evaluating the expectation value of the scale factor. It is shown that the initial singularity of the Universe is avoided by the quantum gravitational effects. |
2310.05200 | Tamara Evstafyeva | Tamara Evstafyeva, Roxana Rosca-Mead, Ulrich Sperhake, Bernd Brugmann | Boson stars in massless and massive scalar-tensor gravity | 26 pages, 20 figures, to match version published in PRD (due to the
large number of figures, some panels may appear blank if viewed from the
browser, we recommend downloading the paper and viewing it locally to avoid
these issues) | Phys. Rev. D 108, 104064, 2023 | 10.1103/PhysRevD.108.104064 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study phenomenological features and stability of boson stars in massless
and massive scalar-tensor theory of gravity with Damour-Esposito-Farese
coupling. This coupling between the tensor and scalar sectors of the theory
leads to a phenomenon called spontaneous scalarization, the onset of which we
investigate by numerically computing families of boson-star models using
shooting and relaxation algorithms. We systematically explore the effects of
the theory's coupling, the mass of the gravitational scalar and the choice of
the bosonic potential on the structure of weakly and strongly scalarized
solutions. Scalarized boson-star models share many common features with neutron
stars in the same scalar-tensor theory of gravity. In particular, scalarization
can result in boson stars with significantly larger radii and masses, which
tend to be energetically favored over their weakly or non-scalarized
counterparts. Overall, we find that boson stars are not quite as susceptible to
scalarization as neutron stars.
| [
{
"created": "Sun, 8 Oct 2023 15:15:14 GMT",
"version": "v1"
},
{
"created": "Fri, 26 Jul 2024 14:59:22 GMT",
"version": "v2"
}
] | 2024-07-29 | [
[
"Evstafyeva",
"Tamara",
""
],
[
"Rosca-Mead",
"Roxana",
""
],
[
"Sperhake",
"Ulrich",
""
],
[
"Brugmann",
"Bernd",
""
]
] | We study phenomenological features and stability of boson stars in massless and massive scalar-tensor theory of gravity with Damour-Esposito-Farese coupling. This coupling between the tensor and scalar sectors of the theory leads to a phenomenon called spontaneous scalarization, the onset of which we investigate by numerically computing families of boson-star models using shooting and relaxation algorithms. We systematically explore the effects of the theory's coupling, the mass of the gravitational scalar and the choice of the bosonic potential on the structure of weakly and strongly scalarized solutions. Scalarized boson-star models share many common features with neutron stars in the same scalar-tensor theory of gravity. In particular, scalarization can result in boson stars with significantly larger radii and masses, which tend to be energetically favored over their weakly or non-scalarized counterparts. Overall, we find that boson stars are not quite as susceptible to scalarization as neutron stars. |
gr-qc/0104058 | Valerio Bozza | V. Bozza, A. Feoli, G. Lambiase, G. Papini, G. Scarpetta | Maximal Acceleration Effects in Kerr Space | 16 pages, 10 figures, to appear on Phys. Lett. A | Phys.Lett. A283 (2001) 53-61 | 10.1016/S0375-9601(01)00230-4 | null | gr-qc | null | We consider a model in which accelerated particles experience line--elements
with maximal acceleration corrections that are introduced by means of
successive approximations. It is shown that approximations higher than the
first need not be considered. The method is then applied to the Kerr metric.
The effective field experienced by accelerated test particles contains
corrections that vanish in the limit $\hbar\to 0$, but otherwise affect the
behaviour of matter greatly. The corrections generate potential barriers that
are external to the horizon and are impervious to classical particles.
| [
{
"created": "Wed, 18 Apr 2001 11:57:52 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Bozza",
"V.",
""
],
[
"Feoli",
"A.",
""
],
[
"Lambiase",
"G.",
""
],
[
"Papini",
"G.",
""
],
[
"Scarpetta",
"G.",
""
]
] | We consider a model in which accelerated particles experience line--elements with maximal acceleration corrections that are introduced by means of successive approximations. It is shown that approximations higher than the first need not be considered. The method is then applied to the Kerr metric. The effective field experienced by accelerated test particles contains corrections that vanish in the limit $\hbar\to 0$, but otherwise affect the behaviour of matter greatly. The corrections generate potential barriers that are external to the horizon and are impervious to classical particles. |
gr-qc/0606075 | Alcides Garat | Alcides Garat | Tetrads in low-energy weak interactions | null | Int.J.Mod.Phys. A33 (2018) no.33, 1850197 | 10.1142/S0217751X1850197X | null | gr-qc | null | Tetrads are introduced in order to study the relationship between gravity and
particle interactions, specially in weak processes at low energy. Through
several examples like inverse Muon decay, elastic Neutrino-Electron scattering,
it is explicitly shown how to assign to each vertex of the corresponding
low-order Feynman diagram in a weak interaction, a particular set of tetrad
vectors. The relationship between the tetrads associated to different vertices
is exhibited explicitly to be generated by a SU(2) local gauge transformation.
| [
{
"created": "Fri, 16 Jun 2006 15:34:55 GMT",
"version": "v1"
}
] | 2019-08-22 | [
[
"Garat",
"Alcides",
""
]
] | Tetrads are introduced in order to study the relationship between gravity and particle interactions, specially in weak processes at low energy. Through several examples like inverse Muon decay, elastic Neutrino-Electron scattering, it is explicitly shown how to assign to each vertex of the corresponding low-order Feynman diagram in a weak interaction, a particular set of tetrad vectors. The relationship between the tetrads associated to different vertices is exhibited explicitly to be generated by a SU(2) local gauge transformation. |
0909.4157 | Carlos Barcelo | C. Barcelo, S. Liberati, S. Sonego and M. Visser | Revisiting the semiclassical gravity scenario for gravitational collapse | 8 pages, proceedings of the ERE2008, aipproc style | Physics and Mathematics of Gravitation, Proceedings of the Spanish
Relativity Meeting (ERE 2008), eds. K.E. Kunze, M. Mars, M.A. Vazquez-Mozo,
pag. 99-106, AIP Conf. Proc. 1122, 2009 | 10.1063/1.3141347 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The existence of extremely dark and compact astronomical bodies is by now a
well established observational fact. On the other hand, classical General
Relativity predicts the existence of black holes which fit very well with the
observations, but do lead to important conceptual problems. In this
contribution we ask ourselves the straightforward question: Are the dark and
compact objects that we have observational evidence for black holes in the
sense of General Relativity? By revising the semiclassical scenario of stellar
collapse we find out that as the result of a collapse some alternative objects
could be formed which might supplant black holes.
| [
{
"created": "Wed, 23 Sep 2009 09:28:28 GMT",
"version": "v1"
}
] | 2015-05-14 | [
[
"Barcelo",
"C.",
""
],
[
"Liberati",
"S.",
""
],
[
"Sonego",
"S.",
""
],
[
"Visser",
"M.",
""
]
] | The existence of extremely dark and compact astronomical bodies is by now a well established observational fact. On the other hand, classical General Relativity predicts the existence of black holes which fit very well with the observations, but do lead to important conceptual problems. In this contribution we ask ourselves the straightforward question: Are the dark and compact objects that we have observational evidence for black holes in the sense of General Relativity? By revising the semiclassical scenario of stellar collapse we find out that as the result of a collapse some alternative objects could be formed which might supplant black holes. |
gr-qc/9311001 | Khatsymovsky | V.Khatsymovsky | On quantization of Regge links | 6 pages, Plain LaTeX, Preprint UUITP-23/1993 | Phys.Lett. B323 (1994) 292-295 | 10.1016/0370-2693(94)91222-X | null | gr-qc | null | In quantum Regge calculus areas of timelike triangles possess discrete
spectrum. This is because bivectors of these triangles are variables
canonically conjugate to orthogonal connection matrices varying in the compact
group. (The scale of quantum of this spectrum is nothing but Plankian one).
This is checked in simple exactly solvable model - dimensionally reduced in
some way Regge calculus.
| [
{
"created": "Mon, 1 Nov 1993 10:59:58 GMT",
"version": "v1"
}
] | 2009-10-22 | [
[
"Khatsymovsky",
"V.",
""
]
] | In quantum Regge calculus areas of timelike triangles possess discrete spectrum. This is because bivectors of these triangles are variables canonically conjugate to orthogonal connection matrices varying in the compact group. (The scale of quantum of this spectrum is nothing but Plankian one). This is checked in simple exactly solvable model - dimensionally reduced in some way Regge calculus. |
gr-qc/9606004 | null | K. S. Virbhadra | Directional naked singularity in general relativity | singlespaced 9 pages, LaTex, no figures | null | null | null | gr-qc astro-ph hep-th | null | We consider a static, axially symmetric, and asymptotically flat exact
solution of the Einstein vacuum equations, known as the gamma metric. This is
characterized by two constant parameters $m$ and $\gamma$. We find that the
total energy associated with this metric is $m \gamma$. Considering the total
energy to be positive, we investigate the nature of a curvature singularity
$r=2m$ ($r$ is the radial coordinate) in this metric. For $\gamma < 1$, this
singularity is globally visible along $\theta = 0$ as well as $\theta = \pi
/2$. However, for $\gamma > 1$, this singularity is though globally naked along
$\theta =\pi/2$, it is not visible (even locally) along $\theta = 0$. Thus,
this exhibits ``directional nakedness'' for $\gamma > 1$. This could have
implications for astrophysics.
| [
{
"created": "Tue, 4 Jun 1996 18:40:00 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Virbhadra",
"K. S.",
""
]
] | We consider a static, axially symmetric, and asymptotically flat exact solution of the Einstein vacuum equations, known as the gamma metric. This is characterized by two constant parameters $m$ and $\gamma$. We find that the total energy associated with this metric is $m \gamma$. Considering the total energy to be positive, we investigate the nature of a curvature singularity $r=2m$ ($r$ is the radial coordinate) in this metric. For $\gamma < 1$, this singularity is globally visible along $\theta = 0$ as well as $\theta = \pi /2$. However, for $\gamma > 1$, this singularity is though globally naked along $\theta =\pi/2$, it is not visible (even locally) along $\theta = 0$. Thus, this exhibits ``directional nakedness'' for $\gamma > 1$. This could have implications for astrophysics. |
gr-qc/0204076 | Roberto Giambo' | Roberto Giambo' | Anisotropic generalizations of de Sitter spacetime | null | Class.Quant.Grav.19:4399-4404,2002 | 10.1088/0264-9381/19/16/312 | null | gr-qc | null | It is known that de Sitter spacetime can be seen as the solution of field
equation for completely isotropic matter. In the present paper a new class of
exact solutions in spherical symmetry is found and discussed, such that the
energy--momentum tensor has two 2--dimensional distinct isotropic subspaces.
| [
{
"created": "Wed, 24 Apr 2002 16:01:14 GMT",
"version": "v1"
}
] | 2010-11-19 | [
[
"Giambo'",
"Roberto",
""
]
] | It is known that de Sitter spacetime can be seen as the solution of field equation for completely isotropic matter. In the present paper a new class of exact solutions in spherical symmetry is found and discussed, such that the energy--momentum tensor has two 2--dimensional distinct isotropic subspaces. |
2402.05752 | Jian-Dong Zhang | Jing Tan, Jian-dong Zhang, Hui-Min Fan, Jianwei Mei | Constraining the EdGB Theory with Extreme Mass-Ratio Inspirals | 9 page, 3 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The Einstein-dilaton-Gauss-Bonnet (EdGB) theory is a modified theory which
include a scalar field to couple with the higher order curvature terms. It has
already been constrained with various observations include the gravitational
wave (GW) with LIGO, Virgo and KAGRA (LVK) Collaboration. In this work, we
study the problem of using the GW of Extreme Mass-Ratio Inspiral (EMRI) to
constrain the EdGB theory. We use the "numerical kludge (NK)" method to
construct the waveform of EMRI in the EdGB theory, focusing on the case when
the central black hole is spinless. We then study how a future space-borne
gravitational wave detector, TianQin, for example, can place constraints on the
EdGB theory through the detection of EMRIs. With the analysis using mismatch
and Fisher Information Matrix (FM), we find that the EdGB parameter
$\sqrt{\alpha}$ is expected to be constrained to the level of
$\sim\mathcal{O}(0.1)$ km.
| [
{
"created": "Thu, 8 Feb 2024 15:36:21 GMT",
"version": "v1"
}
] | 2024-02-09 | [
[
"Tan",
"Jing",
""
],
[
"Zhang",
"Jian-dong",
""
],
[
"Fan",
"Hui-Min",
""
],
[
"Mei",
"Jianwei",
""
]
] | The Einstein-dilaton-Gauss-Bonnet (EdGB) theory is a modified theory which include a scalar field to couple with the higher order curvature terms. It has already been constrained with various observations include the gravitational wave (GW) with LIGO, Virgo and KAGRA (LVK) Collaboration. In this work, we study the problem of using the GW of Extreme Mass-Ratio Inspiral (EMRI) to constrain the EdGB theory. We use the "numerical kludge (NK)" method to construct the waveform of EMRI in the EdGB theory, focusing on the case when the central black hole is spinless. We then study how a future space-borne gravitational wave detector, TianQin, for example, can place constraints on the EdGB theory through the detection of EMRIs. With the analysis using mismatch and Fisher Information Matrix (FM), we find that the EdGB parameter $\sqrt{\alpha}$ is expected to be constrained to the level of $\sim\mathcal{O}(0.1)$ km. |
gr-qc/0601103 | Burkhard Kleihaus | Theodora Ioannidou, Burkhard Kleihaus, and Jutta Kunz | Platonic Gravitating Skyrmions | 13 pages, 4 figures | Phys.Lett. B635 (2006) 161-167 | 10.1016/j.physletb.2006.02.049 | null | gr-qc | null | We construct globally regular gravitating Skyrmions, which possess only
discrete symmetries. In particular, we present tetrahedral and cubic Skyrmions.
The SU(2) Skyrme field is parametrized by an improved harmonic map ansatz.
Consistency then requires also a restricted ansatz for the metric. The
numerical solutions obtained within this approximation are compared to those
obtained in dilaton gravity.
| [
{
"created": "Tue, 24 Jan 2006 18:39:07 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Ioannidou",
"Theodora",
""
],
[
"Kleihaus",
"Burkhard",
""
],
[
"Kunz",
"Jutta",
""
]
] | We construct globally regular gravitating Skyrmions, which possess only discrete symmetries. In particular, we present tetrahedral and cubic Skyrmions. The SU(2) Skyrme field is parametrized by an improved harmonic map ansatz. Consistency then requires also a restricted ansatz for the metric. The numerical solutions obtained within this approximation are compared to those obtained in dilaton gravity. |
2003.08344 | Saulo Pereira H | R. de C. Lima, Jos\'e A. C. Nogales and S. H. Pereira | Gravitational entropy of wormholes with exotic matter and in galactic
halos | 18 pages, 3 figures | IJMPD 29, (2020) 2050015 | 10.1142/S0218271820500157 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we study and compare the features of gravitational entropy near
the throat of transversable wormholes formed by exotic matter and wormholes in
galactic halos. We have verified that gravitational entropy and entropy density
of these wormholes in regions near their throats are indistinguishable for
objects of same throat, despite the fact they are described by different
metrics and by distinct energy-momentum tensors. We have found that the
gravitational entropy density diverges near the throat for both cases, probably
due to a non-trivial topology at this point, however allowing the interesting
interpretation that a maximum flux of information can be carried through the
throat of these wormholes. In addition, we have found that both are endowed
with an entropic behaviour similar to Hawking-Bekenstein's entropy of
non-rotating and null charge black holes.
| [
{
"created": "Wed, 18 Mar 2020 17:18:00 GMT",
"version": "v1"
}
] | 2020-03-19 | [
[
"Lima",
"R. de C.",
""
],
[
"Nogales",
"José A. C.",
""
],
[
"Pereira",
"S. H.",
""
]
] | In this work we study and compare the features of gravitational entropy near the throat of transversable wormholes formed by exotic matter and wormholes in galactic halos. We have verified that gravitational entropy and entropy density of these wormholes in regions near their throats are indistinguishable for objects of same throat, despite the fact they are described by different metrics and by distinct energy-momentum tensors. We have found that the gravitational entropy density diverges near the throat for both cases, probably due to a non-trivial topology at this point, however allowing the interesting interpretation that a maximum flux of information can be carried through the throat of these wormholes. In addition, we have found that both are endowed with an entropic behaviour similar to Hawking-Bekenstein's entropy of non-rotating and null charge black holes. |
2006.16332 | Kristina Gudkova | A. D. Dolgov, K. S. Gudkova | Massive photons and electrically charged black holes | null | null | 10.1016/j.physletb.2020.135844 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The characteristic time of disappearance of electric field in massive
electrodynamics during the capture of electric charge by black holes is
calculated. It is shown that this time does not depend upon the photon mass.
The electric field at large distances disappears with the speed of light.
| [
{
"created": "Mon, 29 Jun 2020 19:35:33 GMT",
"version": "v1"
}
] | 2020-10-07 | [
[
"Dolgov",
"A. D.",
""
],
[
"Gudkova",
"K. S.",
""
]
] | The characteristic time of disappearance of electric field in massive electrodynamics during the capture of electric charge by black holes is calculated. It is shown that this time does not depend upon the photon mass. The electric field at large distances disappears with the speed of light. |
1106.3027 | Sandipan Sengupta | Romesh K. Kaul and Sandipan Sengupta | Topological parameters in gravity | references added | Phys. Rev. D 85, 024026 (2012) | 10.1103/PhysRevD.85.024026 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present the Hamiltonian analysis of the theory of gravity based on a
Lagrangian density containing Hilbert-Palatini term along with three
topological densities, Nieh-Yan, Pontryagin and Euler. The addition of these
topological terms modifies the symplectic structure non-trivially. The
resulting canonical theory develops a dependence on three parameters which are
coefficients of these terms. In the time gauge, we obtain a real SU (2) gauge
theoretic description with a set of seven first class constraints corresponding
to three SU (2) rotations, three spatial diffeomorphism and one to evolution in
a timelike direction. Inverse of the coefficient of Nieh-Yan term, identified
as Barbero-Immirzi parameter, acts as the coupling constant of the gauge
theory.
| [
{
"created": "Wed, 15 Jun 2011 17:17:12 GMT",
"version": "v1"
},
{
"created": "Mon, 20 Jun 2011 05:30:10 GMT",
"version": "v2"
}
] | 2012-01-24 | [
[
"Kaul",
"Romesh K.",
""
],
[
"Sengupta",
"Sandipan",
""
]
] | We present the Hamiltonian analysis of the theory of gravity based on a Lagrangian density containing Hilbert-Palatini term along with three topological densities, Nieh-Yan, Pontryagin and Euler. The addition of these topological terms modifies the symplectic structure non-trivially. The resulting canonical theory develops a dependence on three parameters which are coefficients of these terms. In the time gauge, we obtain a real SU (2) gauge theoretic description with a set of seven first class constraints corresponding to three SU (2) rotations, three spatial diffeomorphism and one to evolution in a timelike direction. Inverse of the coefficient of Nieh-Yan term, identified as Barbero-Immirzi parameter, acts as the coupling constant of the gauge theory. |
2109.05994 | M.V.S. Saketh | M. V. S. Saketh, Justin Vines, Jan Steinhoff, Alessandra Buonanno | Conservative and radiative dynamics in classical relativistic scattering
and bound systems | 25 pages | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | As recent work continues to demonstrate, the study of relativistic scattering
processes leads to valuable insights and computational tools applicable to the
relativistic bound-orbit two-body problem. This is particularly relevant in the
post-Minkowskian approach to the gravitational two-body problem, where the
field has only recently reached a full description of certain physical
observables for scattering orbits, including radiative effects, at the third
post-Minkowskian (3PM) order. As an historically instructive simpler example,
we consider here the analogous problem in electromagnetism in flat spacetime.
We compute for the first time the changes in linear momentum of each particle
and the total radiated linear momentum, in the relativistic classical
scattering of two point-charges, at sixth order in the charges (analogous to
3PM order in gravity). We accomplish this here via direct iteration of the
classical equations of motion, while making comparisons where possible to
results from quantum scattering amplitudes, with the aim of contributing to the
elucidation of conceptual issues and scalability on both sides. We also discuss
further extensions to radiative quantities of recently established relations
which analytically continue certain observables from the scattering regime to
the regime of bound orbits, applicable for both the electromagnetic and
gravitational cases.
| [
{
"created": "Mon, 13 Sep 2021 14:13:05 GMT",
"version": "v1"
}
] | 2021-09-14 | [
[
"Saketh",
"M. V. S.",
""
],
[
"Vines",
"Justin",
""
],
[
"Steinhoff",
"Jan",
""
],
[
"Buonanno",
"Alessandra",
""
]
] | As recent work continues to demonstrate, the study of relativistic scattering processes leads to valuable insights and computational tools applicable to the relativistic bound-orbit two-body problem. This is particularly relevant in the post-Minkowskian approach to the gravitational two-body problem, where the field has only recently reached a full description of certain physical observables for scattering orbits, including radiative effects, at the third post-Minkowskian (3PM) order. As an historically instructive simpler example, we consider here the analogous problem in electromagnetism in flat spacetime. We compute for the first time the changes in linear momentum of each particle and the total radiated linear momentum, in the relativistic classical scattering of two point-charges, at sixth order in the charges (analogous to 3PM order in gravity). We accomplish this here via direct iteration of the classical equations of motion, while making comparisons where possible to results from quantum scattering amplitudes, with the aim of contributing to the elucidation of conceptual issues and scalability on both sides. We also discuss further extensions to radiative quantities of recently established relations which analytically continue certain observables from the scattering regime to the regime of bound orbits, applicable for both the electromagnetic and gravitational cases. |
1805.04900 | Bogeun Gwak | Bogeun Gwak | Coalescence of Kerr Black Holes: Binary Systems from GW150914 to
GW170814 | 27 pages, 22 figures | Entropy 21 (2019) no. 10 | 10.3390/e21101017 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the energy of the gravitational wave from a binary black hole
merger by the coalescence of two Kerr black holes with an orbital angular
momentum. The coalescence is constructed to be consistent with particle
absorption in the limit in which the primary black hole is sufficiently large
compared with the secondary black hole. In this limit, we analytically obtain
an effective gravitational spin--orbit interaction dependent on the alignments
of the angular momenta. Then, binary systems with various parameters including
equal masses are numerically analyzed. According to the numerical analysis, the
energy of the gravitational wave still depends on the effective interactions,
as expected from the analytical form. In particular, we ensure that the final
black hole obtains a large portion of its spin angular momentum from the
orbital angular momentum of the initial binary black hole. To estimate the
angular momentum released by the gravitational wave in the actual binary black
hole, we apply our results to observations at the Laser Interferometer
Gravitational-Wave Observatory: GW150914, GW151226, GW170104, GW170608, and
GW170814.
| [
{
"created": "Sun, 13 May 2018 15:29:57 GMT",
"version": "v1"
}
] | 2019-10-22 | [
[
"Gwak",
"Bogeun",
""
]
] | We investigate the energy of the gravitational wave from a binary black hole merger by the coalescence of two Kerr black holes with an orbital angular momentum. The coalescence is constructed to be consistent with particle absorption in the limit in which the primary black hole is sufficiently large compared with the secondary black hole. In this limit, we analytically obtain an effective gravitational spin--orbit interaction dependent on the alignments of the angular momenta. Then, binary systems with various parameters including equal masses are numerically analyzed. According to the numerical analysis, the energy of the gravitational wave still depends on the effective interactions, as expected from the analytical form. In particular, we ensure that the final black hole obtains a large portion of its spin angular momentum from the orbital angular momentum of the initial binary black hole. To estimate the angular momentum released by the gravitational wave in the actual binary black hole, we apply our results to observations at the Laser Interferometer Gravitational-Wave Observatory: GW150914, GW151226, GW170104, GW170608, and GW170814. |
1309.6163 | Shahpoor Moradi | Shahpoor Moradi, Roberto Pierini and Stefano Mancini | Spin-Particles Entanglement in Robertson-Walker Spacetime | null | Phys. Rev. D 89, 024022 (2014) | 10.1103/PhysRevD.89.024022 | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the entanglement between two modes of Dirac field in an expanding
spacetime characterized by the Robertson-Walker metric. This spacetime model
turns out to be asymptotically (in the remote past and far future regions)
Minkowskian. Then, on the one hand we show entanglement creation between
particles and anti-particles when passing from remote past to far future. On
the other hand we show that particles entanglement in the remote past degrades
into the far future. These effects are traced back to particles creation. In
our analysis we highlight the role of spin (polarization) of particles and
compare the results with those obtainable without accounting for it.
| [
{
"created": "Mon, 23 Sep 2013 18:53:22 GMT",
"version": "v1"
}
] | 2014-01-21 | [
[
"Moradi",
"Shahpoor",
""
],
[
"Pierini",
"Roberto",
""
],
[
"Mancini",
"Stefano",
""
]
] | We study the entanglement between two modes of Dirac field in an expanding spacetime characterized by the Robertson-Walker metric. This spacetime model turns out to be asymptotically (in the remote past and far future regions) Minkowskian. Then, on the one hand we show entanglement creation between particles and anti-particles when passing from remote past to far future. On the other hand we show that particles entanglement in the remote past degrades into the far future. These effects are traced back to particles creation. In our analysis we highlight the role of spin (polarization) of particles and compare the results with those obtainable without accounting for it. |
0909.2320 | Wlodzimierz Piechocki | Wlodzimierz Piechocki | Energy scale of the Big Bounce | Talk presented at the conference: XXV Max Born Symposium `The Planck
Scale', Wroclaw, 29 June - 3 July, 2009 | null | 10.1063/1.3284388 | INS 09 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We examine the nature of the cosmological big-bounce (BB) transition within
the loop geometry underlying Loop Quantum Cosmology (LQC) at classical and
quantum levels. Our canonical quantization method is an alternative to the
standard LQC. Our method opens the door for analyzes of spectra of physical
observables like energy density and volume operator. We find that one cannot
determine the energy scale specific to BB by making use of the loop geometry
without an extra input from observational cosmology.
| [
{
"created": "Sat, 12 Sep 2009 10:27:12 GMT",
"version": "v1"
}
] | 2015-05-14 | [
[
"Piechocki",
"Wlodzimierz",
""
]
] | We examine the nature of the cosmological big-bounce (BB) transition within the loop geometry underlying Loop Quantum Cosmology (LQC) at classical and quantum levels. Our canonical quantization method is an alternative to the standard LQC. Our method opens the door for analyzes of spectra of physical observables like energy density and volume operator. We find that one cannot determine the energy scale specific to BB by making use of the loop geometry without an extra input from observational cosmology. |
gr-qc/0101027 | Jozef Sima | Jozef Sima and Miroslav Sukenik | Determination of Upper Limit of Stars Mass Based on Model of Expansive
Nondecelerative Universe | 3 pages, LaTeX | null | null | SS-01-02 | gr-qc | null | Incorporation of the Vaidya metric in the model of Expansive Nondecelerative
Universe allows to localize the energy density of gravitational field that,
subsequently, enables to determine the upper limit of stars mass. The upper
limit decreases with cosmological time and at present is close to 30-fold of
our Sun mass.
| [
{
"created": "Mon, 8 Jan 2001 11:31:03 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Sima",
"Jozef",
""
],
[
"Sukenik",
"Miroslav",
""
]
] | Incorporation of the Vaidya metric in the model of Expansive Nondecelerative Universe allows to localize the energy density of gravitational field that, subsequently, enables to determine the upper limit of stars mass. The upper limit decreases with cosmological time and at present is close to 30-fold of our Sun mass. |
2305.12466 | Rong-Jia Yang | Ziqiang Cai, Tong-Yu He, Wen-Qian Wang, Zhan-Wen Han, Rong-Jia Yang | Types of the geodesic motions in Kerr-Sen-AdS$_{4}$ spacetime | 12 pages, 14 figures | Universe 10 (2024) 3, 133 | 10.3390/universe10030133 | null | gr-qc hep-th | http://creativecommons.org/licenses/by-nc-sa/4.0/ | We consider the geodesic motions in the Kerr-Sen-AdS$_4$ spacetime. We obtain
the equations of motion for light rays and test particles. Using the parametric
diagrams, we shown some regions where the radial and latitudinal geodesic
motions are allowed. We analyse the impact of parameter related to dilatonic
scalar on the orbit and find that it will result in more rich and complex
orbital types.
| [
{
"created": "Sun, 21 May 2023 14:05:49 GMT",
"version": "v1"
},
{
"created": "Sun, 12 Nov 2023 12:56:52 GMT",
"version": "v2"
}
] | 2024-04-11 | [
[
"Cai",
"Ziqiang",
""
],
[
"He",
"Tong-Yu",
""
],
[
"Wang",
"Wen-Qian",
""
],
[
"Han",
"Zhan-Wen",
""
],
[
"Yang",
"Rong-Jia",
""
]
] | We consider the geodesic motions in the Kerr-Sen-AdS$_4$ spacetime. We obtain the equations of motion for light rays and test particles. Using the parametric diagrams, we shown some regions where the radial and latitudinal geodesic motions are allowed. We analyse the impact of parameter related to dilatonic scalar on the orbit and find that it will result in more rich and complex orbital types. |
gr-qc/0311007 | Matthew R. Francis | Matthew R. Francis and Arthur Kosowsky | Geometric Algebra Techniques for General Relativity | 34 pages, 0 figures; submitted to Annals of Physics | Annals Phys. 311 (2004) 459-502 | 10.1016/j.aop.2003.12.009 | null | gr-qc | null | Geometric (Clifford) algebra provides an efficient mathematical language for
describing physical problems. We formulate general relativity in this language.
The resulting formalism combines the efficiency of differential forms with the
straightforwardness of coordinate methods. We focus our attention on
orthonormal frames and the associated connection bivector, using them to find
the Schwarzschild and Kerr solutions, along with a detailed exposition of the
Petrov types for the Weyl tensor.
| [
{
"created": "Mon, 3 Nov 2003 16:43:29 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Francis",
"Matthew R.",
""
],
[
"Kosowsky",
"Arthur",
""
]
] | Geometric (Clifford) algebra provides an efficient mathematical language for describing physical problems. We formulate general relativity in this language. The resulting formalism combines the efficiency of differential forms with the straightforwardness of coordinate methods. We focus our attention on orthonormal frames and the associated connection bivector, using them to find the Schwarzschild and Kerr solutions, along with a detailed exposition of the Petrov types for the Weyl tensor. |
1702.02410 | Matti Savelainen | Matti Savelainen | Four-form field versus fundamental scalar field | 14 pages | JETP Lett. 105 (2017) no.10, 682-685 | 10.1134/S0021364017100034 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A modified-gravity theory with a four-form field strength $F$, a variable
gravitational coupling parameter $G(F)$, and a standard matter action is
considered here. Maxwell and Einstein equations are now derived when including
to action also derivates of $F$. The energy momentum tensor of the 4-form field
contains both the part, which is typical for the fundamental (pseudo)scalar,
and the part, which cancels the divergent contribution of the zero-point
energies of quantum fields to the vacuum energy and thus leads to the natural
nullification of the cosmological constant in Minkowski vacuum.
| [
{
"created": "Wed, 8 Feb 2017 12:59:38 GMT",
"version": "v1"
}
] | 2017-07-27 | [
[
"Savelainen",
"Matti",
""
]
] | A modified-gravity theory with a four-form field strength $F$, a variable gravitational coupling parameter $G(F)$, and a standard matter action is considered here. Maxwell and Einstein equations are now derived when including to action also derivates of $F$. The energy momentum tensor of the 4-form field contains both the part, which is typical for the fundamental (pseudo)scalar, and the part, which cancels the divergent contribution of the zero-point energies of quantum fields to the vacuum energy and thus leads to the natural nullification of the cosmological constant in Minkowski vacuum. |
1704.08712 | Sergey Chervon | Sergey V. Chervon, Igor V. Fomin and Aroonkumar Beesham | The method of generating functions in exact scalar field cosmology | 15 parges | null | 10.1140/epjc/s10052-018-5795-z | LGCA2017/CH3 and LMME2017/F3 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Exact solutions construction in scalar fields cosmology is of growing
interest. In this work we review the results which obtained with the help of
one of the most effective method. Namely, the method of generating functions
for exact solutions construction in the scalar field cosmology. We also
included into debate the superpotential method which may be considered as the
bridge to slow roll approximation equations. Basing on the review, we suggested
classification for the generating functions and found connection for all of
them with the superpotential.
| [
{
"created": "Thu, 27 Apr 2017 18:41:06 GMT",
"version": "v1"
},
{
"created": "Sat, 31 Mar 2018 09:54:35 GMT",
"version": "v2"
}
] | 2018-05-09 | [
[
"Chervon",
"Sergey V.",
""
],
[
"Fomin",
"Igor V.",
""
],
[
"Beesham",
"Aroonkumar",
""
]
] | Exact solutions construction in scalar fields cosmology is of growing interest. In this work we review the results which obtained with the help of one of the most effective method. Namely, the method of generating functions for exact solutions construction in the scalar field cosmology. We also included into debate the superpotential method which may be considered as the bridge to slow roll approximation equations. Basing on the review, we suggested classification for the generating functions and found connection for all of them with the superpotential. |
gr-qc/0208018 | Jonathan Halliwell | J.J. Halliwell | The Interpretation of Quantum Cosmology and the Problem of Time | 22 pages, Latex, 1 figure. To appear in Proceedings of Stephen
Hawking's 60th Birthday Conference | null | null | Imperial TP/1-02/23 | gr-qc | null | The development of quantum cosmology, in which Stephen Hawking played a
crucial role, has frequently encountered substantial conceptual and technical
difficulties related to the problem of time in quantum gravity and to general
issues concerning the foundations of quantum theory. In this contribution to
Stephen's 60th Birthday Conference, I describe some recent work in which the
decoherent histories approach to quantum theory is used to quantize simple
cosmological models and perhaps shed some light on some of these difficulties.
| [
{
"created": "Wed, 7 Aug 2002 13:02:39 GMT",
"version": "v1"
},
{
"created": "Thu, 8 Aug 2002 15:07:32 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Halliwell",
"J. J.",
""
]
] | The development of quantum cosmology, in which Stephen Hawking played a crucial role, has frequently encountered substantial conceptual and technical difficulties related to the problem of time in quantum gravity and to general issues concerning the foundations of quantum theory. In this contribution to Stephen's 60th Birthday Conference, I describe some recent work in which the decoherent histories approach to quantum theory is used to quantize simple cosmological models and perhaps shed some light on some of these difficulties. |
0905.3226 | Jiliang Jing | Jieci Wang, Qiyuan Pan, Songbai Chen and Jiliang Jing | Entanglement of coupled massive scalar field in background of dilaton
black hole | 11 pages, 2 figures, Accepted by PLB | Phys.Lett.B677:186-189,2009 | 10.1016/j.physletb.2009.05.028 | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The entanglement of the coupled massive scalar field in the spacetime of a
Garfinkle-Horowitz-Strominger(GHS) dilaton black hole has been investigated. It
is found that the entanglement does not depend on the mass of the particle and
the coupling between the scalar field and the gravitational field, but it
decreases as the dilaton parameter $D$ increases. It is interesting to note
that in the limit of $D\to M$, corresponding to the case of an extreme black
hole, the state has no longer distillable entanglement for any state parameter
$\alpha$, but the mutual information equals to a nonvanishing minimum value,
which indicates that the total correlations consist of classical correlations
plus bound entanglement in this limit.
| [
{
"created": "Wed, 20 May 2009 07:03:34 GMT",
"version": "v1"
}
] | 2010-04-30 | [
[
"Wang",
"Jieci",
""
],
[
"Pan",
"Qiyuan",
""
],
[
"Chen",
"Songbai",
""
],
[
"Jing",
"Jiliang",
""
]
] | The entanglement of the coupled massive scalar field in the spacetime of a Garfinkle-Horowitz-Strominger(GHS) dilaton black hole has been investigated. It is found that the entanglement does not depend on the mass of the particle and the coupling between the scalar field and the gravitational field, but it decreases as the dilaton parameter $D$ increases. It is interesting to note that in the limit of $D\to M$, corresponding to the case of an extreme black hole, the state has no longer distillable entanglement for any state parameter $\alpha$, but the mutual information equals to a nonvanishing minimum value, which indicates that the total correlations consist of classical correlations plus bound entanglement in this limit. |
2101.11015 | Miren Radia | Miren Radia, Ulrich Sperhake, Emanuele Berti and Robin Croft | Anomalies in the gravitational recoil of eccentric black-hole mergers
with unequal mass ratios | 14 pages, 7 figures, to match published version in Phys. Rev. D | Phys. Rev. D 103, 104006 (2021) | 10.1103/PhysRevD.103.104006 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The radiation of linear momentum imparts a recoil (or "kick") to the center
of mass of a merging black hole binary system. Recent numerical relativity
calculations have shown that eccentricity can lead to an approximate 25%
increase in recoil velocities for equal-mass, spinning binaries with spins
lying in the orbital plane ("superkick" configurations) [U Sperhake et al.
Phys. Rev. D 101 (2020) 024044 (arXiv:1910.01598)]. Here we investigate the
impact of nonzero eccentricity on the kick magnitude and gravitational-wave
emission of nonspinning, unequal-mass black hole binaries. We confirm that
nonzero eccentricities at merger can lead to kicks which are larger by up to
~25% relative to the quasicircular case. We also find that the kick velocity
$v$ has an oscillatory dependence on eccentricity, that we interpret as a
consequence of changes in the angle between the infall direction at merger and
the apoapsis (or periapsis) direction.
| [
{
"created": "Tue, 26 Jan 2021 19:00:02 GMT",
"version": "v1"
},
{
"created": "Tue, 11 May 2021 10:40:10 GMT",
"version": "v2"
}
] | 2021-05-12 | [
[
"Radia",
"Miren",
""
],
[
"Sperhake",
"Ulrich",
""
],
[
"Berti",
"Emanuele",
""
],
[
"Croft",
"Robin",
""
]
] | The radiation of linear momentum imparts a recoil (or "kick") to the center of mass of a merging black hole binary system. Recent numerical relativity calculations have shown that eccentricity can lead to an approximate 25% increase in recoil velocities for equal-mass, spinning binaries with spins lying in the orbital plane ("superkick" configurations) [U Sperhake et al. Phys. Rev. D 101 (2020) 024044 (arXiv:1910.01598)]. Here we investigate the impact of nonzero eccentricity on the kick magnitude and gravitational-wave emission of nonspinning, unequal-mass black hole binaries. We confirm that nonzero eccentricities at merger can lead to kicks which are larger by up to ~25% relative to the quasicircular case. We also find that the kick velocity $v$ has an oscillatory dependence on eccentricity, that we interpret as a consequence of changes in the angle between the infall direction at merger and the apoapsis (or periapsis) direction. |
2211.01582 | Michael Good | Michael R.R. Good | Spacetime continuity and quantum information loss | 9 page, 5 figures, 1 table | Universe 2018, 4(11), 122 | 10.3390/universe4110122 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Continuity across the shock wave of two regions in the metric during the
formation of a black hole can be relaxed in order to achieve information
preservation. A Planck scale sized spacetime discontinuity leads to unitarity
(a constant asymptotic entanglement entropy) by restricting the origin of
coordinates (moving mirror) to be timelike. Moreover, thermal equilibration
occurs and total evaporation energy emitted is finite.
| [
{
"created": "Thu, 3 Nov 2022 04:26:33 GMT",
"version": "v1"
}
] | 2022-11-04 | [
[
"Good",
"Michael R. R.",
""
]
] | Continuity across the shock wave of two regions in the metric during the formation of a black hole can be relaxed in order to achieve information preservation. A Planck scale sized spacetime discontinuity leads to unitarity (a constant asymptotic entanglement entropy) by restricting the origin of coordinates (moving mirror) to be timelike. Moreover, thermal equilibration occurs and total evaporation energy emitted is finite. |
2008.01661 | Zhongwen Feng | Zhong-Wen Feng, Xia Zhou, Shi-Qi Zhou | The generalized uncertainty principle impact onto the black hole
thermodynamic phase transition | 9 Pages, 5 figures | Front. Phys. 2022, 10: 887410 | 10.3389/fphy.2022.887410 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | In this work, we conduct a study regarding the thermodynamic evolution and
the phase transition of a black hole in a finite spherical cavity subject to
the generalized uncertainty principle. The results demonstrate that both the
positive and negative generalized uncertainty principle parameters $\beta_0$
can significantly affect the thermodynamic quantities, stability, critical
behavior, and phase transition of the black hole. For $\beta_0>0$, the black
hole forms a remnant with finite temperature, finite mass, and zero local heat
capacity in the last stages of evolution, which can be regarded as an
elementary particle. Meanwhile, it undergoes one second-order phase transition
and two Hawking-Page-type phase transitions. The Gross-Perry-Yaffe phase
transition occurs for both large black hole configuration and small black hole
configuration. For $\beta_0<0$, the Gross-Perry-Yaffe phase transition occurs
only for large black hole configuration, and the temperature and heat capacity
of black hole remnant is finite, whereas its mass is zero. This indicates the
remnant is metastable and would be in the Hawking-Page-type phase transition
forever. Specifically, according to the viewpoint of corpuscular gravity, the
remnant can be interpreted as an additional metastable tiny black hole
configuration, which never appears in the original case and the positive
correction case.
| [
{
"created": "Mon, 3 Aug 2020 03:57:38 GMT",
"version": "v1"
},
{
"created": "Wed, 9 Dec 2020 09:47:55 GMT",
"version": "v2"
},
{
"created": "Wed, 18 May 2022 03:19:54 GMT",
"version": "v3"
}
] | 2022-05-26 | [
[
"Feng",
"Zhong-Wen",
""
],
[
"Zhou",
"Xia",
""
],
[
"Zhou",
"Shi-Qi",
""
]
] | In this work, we conduct a study regarding the thermodynamic evolution and the phase transition of a black hole in a finite spherical cavity subject to the generalized uncertainty principle. The results demonstrate that both the positive and negative generalized uncertainty principle parameters $\beta_0$ can significantly affect the thermodynamic quantities, stability, critical behavior, and phase transition of the black hole. For $\beta_0>0$, the black hole forms a remnant with finite temperature, finite mass, and zero local heat capacity in the last stages of evolution, which can be regarded as an elementary particle. Meanwhile, it undergoes one second-order phase transition and two Hawking-Page-type phase transitions. The Gross-Perry-Yaffe phase transition occurs for both large black hole configuration and small black hole configuration. For $\beta_0<0$, the Gross-Perry-Yaffe phase transition occurs only for large black hole configuration, and the temperature and heat capacity of black hole remnant is finite, whereas its mass is zero. This indicates the remnant is metastable and would be in the Hawking-Page-type phase transition forever. Specifically, according to the viewpoint of corpuscular gravity, the remnant can be interpreted as an additional metastable tiny black hole configuration, which never appears in the original case and the positive correction case. |
1406.3452 | Luis Herrera | L. Herrera, A. Di Prisco and J. Ospino | Shear-free axially symmetric dissipative fluids | 5 pages Revtex4-1. Published in Phys. Rev. D. Some typos corrected | Phys. Rev. D89,127502, (2014) | 10.1103/PhysRevD.89.127502 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the general properties of axially symmetric dissipative
configurations under the shear-free condition. The link between the magnetic
part of the Weyl tensor and the vorticity, as well as the role of the
dissipative fluxes, are clearly exhibited. As a particular case we examine the
geodesic fluid. In this latter case, the magnetic part of the Weyl tensor
always vanishes, suggesting that no gravitational radiation is produced during
the evolution. Also (for the geodesic case), in the absence of dissipation, the
system evolves towards a FRW spacetime if the expansion scalar is positive.
| [
{
"created": "Fri, 13 Jun 2014 08:38:36 GMT",
"version": "v1"
},
{
"created": "Thu, 26 Jun 2014 07:57:05 GMT",
"version": "v2"
}
] | 2015-06-22 | [
[
"Herrera",
"L.",
""
],
[
"Di Prisco",
"A.",
""
],
[
"Ospino",
"J.",
""
]
] | We study the general properties of axially symmetric dissipative configurations under the shear-free condition. The link between the magnetic part of the Weyl tensor and the vorticity, as well as the role of the dissipative fluxes, are clearly exhibited. As a particular case we examine the geodesic fluid. In this latter case, the magnetic part of the Weyl tensor always vanishes, suggesting that no gravitational radiation is produced during the evolution. Also (for the geodesic case), in the absence of dissipation, the system evolves towards a FRW spacetime if the expansion scalar is positive. |
1910.12182 | Zhen-Ming Xu | Zhen-Ming Xu, Bin Wu, and Wen-Li Yang | Ruppeiner thermodynamic geometry for the Schwarzschild-AdS black hole | v1:5 pages, twocolumn, 2 figures; v2:add References and some
comments, published in Physical Review D | Phys. Rev. D 101 (2020) 024018 | 10.1103/PhysRevD.101.024018 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Due to the non-independence of entropy and thermodynamic volume for
spherically symmetric black holes in the AdS spacetime, when applying the
Ruppeiner thermodynamic geometry theory to these black holes, we often
encounter an unavoidable problem of the singularity about the line element of
thermodynamic geometry. In this paper, we propose a basic and natural scheme
for dealing with the thermodynamic geometry of spherically symmetric AdS black
holes. We point out that enthalpy, not internal energy, is the fundamental
thermodynamic characteristic function for the Ruppeiner thermodynamic geometry.
Based on this fact, we give the specific forms of the line element of
thermodynamic geometry for Schwarzschild AdS (SAdS) black hole in different
phase spaces and the results show that the thermodynamic curvatures obtained in
different phase spaces are equivalent. It is shown that the thermodynamic
curvature is negative which implies that the attractive interaction dominates
between black hole molecules for the SAdS black hole. Meanwhile we also give an
approximate expression of the thermodynamic curvature of the Schwarzschild
black hole which indicates that the black hole is dominated by repulsion on low
temperature region and by attraction on high temperature region.
| [
{
"created": "Sun, 27 Oct 2019 05:05:39 GMT",
"version": "v1"
},
{
"created": "Tue, 7 Jan 2020 02:04:55 GMT",
"version": "v2"
}
] | 2020-01-08 | [
[
"Xu",
"Zhen-Ming",
""
],
[
"Wu",
"Bin",
""
],
[
"Yang",
"Wen-Li",
""
]
] | Due to the non-independence of entropy and thermodynamic volume for spherically symmetric black holes in the AdS spacetime, when applying the Ruppeiner thermodynamic geometry theory to these black holes, we often encounter an unavoidable problem of the singularity about the line element of thermodynamic geometry. In this paper, we propose a basic and natural scheme for dealing with the thermodynamic geometry of spherically symmetric AdS black holes. We point out that enthalpy, not internal energy, is the fundamental thermodynamic characteristic function for the Ruppeiner thermodynamic geometry. Based on this fact, we give the specific forms of the line element of thermodynamic geometry for Schwarzschild AdS (SAdS) black hole in different phase spaces and the results show that the thermodynamic curvatures obtained in different phase spaces are equivalent. It is shown that the thermodynamic curvature is negative which implies that the attractive interaction dominates between black hole molecules for the SAdS black hole. Meanwhile we also give an approximate expression of the thermodynamic curvature of the Schwarzschild black hole which indicates that the black hole is dominated by repulsion on low temperature region and by attraction on high temperature region. |
1606.01132 | Prasia P | P Prasia and V C Kuriakose | Quasi Normal Modes and P-V Criticallity for scalar perturbations in a
class of dRGT massive gravity around Black Holes | Accepted for publication in 'General Relativity and Gravitation'-
Springer | Gen. Relativ. Gravit., 48(7) 48: 89 (2016) | 10.1007/s10714-016-2083-9 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate black holes in a class of dRGT massive gravity for their quasi
normal modes (QNMs) for neutral and charged ones using Improved Asymptotic
Iteration Method (Improved AIM) and their thermodynamic behavior. The QNMs are
studied for different values of the massive parameter m_g for both neutral and
charged dRGT black holes under a massless scalar perturbation. As m_g
increases, the magnitude of the quasi normal frequencies are found to be
increasing. The results are also compared with the Schwarzchild de Sitter (SdS)
case. P-V criticallity of the aforesaid black hoels under massles scalar
perturbation in the de Sitter space are also studied in this paper. It is found
that the thermodynamic behavior of a neutral black hole shows no physically
feasible phase transition while a charged black hole shows a definite phase
transition.
| [
{
"created": "Fri, 3 Jun 2016 15:18:45 GMT",
"version": "v1"
}
] | 2017-01-31 | [
[
"Prasia",
"P",
""
],
[
"Kuriakose",
"V C",
""
]
] | We investigate black holes in a class of dRGT massive gravity for their quasi normal modes (QNMs) for neutral and charged ones using Improved Asymptotic Iteration Method (Improved AIM) and their thermodynamic behavior. The QNMs are studied for different values of the massive parameter m_g for both neutral and charged dRGT black holes under a massless scalar perturbation. As m_g increases, the magnitude of the quasi normal frequencies are found to be increasing. The results are also compared with the Schwarzchild de Sitter (SdS) case. P-V criticallity of the aforesaid black hoels under massles scalar perturbation in the de Sitter space are also studied in this paper. It is found that the thermodynamic behavior of a neutral black hole shows no physically feasible phase transition while a charged black hole shows a definite phase transition. |
1312.0062 | Abhishek Majhi | Abhishek Majhi | Thermodynamic partition function from quantum theory for black hole
horizons in loop quantum gravity | title changed and modifications made to match the published version | Advances in High Energy Physics, vol. 2016, Article ID 1068757, 10
pages, 2016 | 10.1155/2016/1068757 | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We establish the link between the thermodynamics and the quantum theory of
black hole horizons through the construction of the thermodynamic partition
function, partly based on some physically plausible arguments, by beginning
from the description of quantum states of the horizon, considering loop quantum
gravity(LQG) as the underlying theory. Although, the effective
`thermalized\rq{} form of the partition function has been previously used in
the literature to study the effect of thermal fluctuations of the black hole
horizon, nonetheless the direct link to any existing quantum theory (which is
here taken to be LQG), especially a derivation of the partition function from
the quantum states of the horizon, appears to be hitherto absent. This work is
an attempt to bridge this small, but essential, gap that appears to be present
between the existing literature of quantum theory and thermodynamics of black
holes. Further, it may be emphasized that this work is {\it only} concerned
with the {\it metric independent} approaches to black hole thermodynamics.
| [
{
"created": "Sat, 30 Nov 2013 04:51:20 GMT",
"version": "v1"
},
{
"created": "Sat, 28 Jun 2014 15:17:30 GMT",
"version": "v2"
},
{
"created": "Thu, 22 Sep 2016 16:36:48 GMT",
"version": "v3"
}
] | 2016-09-23 | [
[
"Majhi",
"Abhishek",
""
]
] | We establish the link between the thermodynamics and the quantum theory of black hole horizons through the construction of the thermodynamic partition function, partly based on some physically plausible arguments, by beginning from the description of quantum states of the horizon, considering loop quantum gravity(LQG) as the underlying theory. Although, the effective `thermalized\rq{} form of the partition function has been previously used in the literature to study the effect of thermal fluctuations of the black hole horizon, nonetheless the direct link to any existing quantum theory (which is here taken to be LQG), especially a derivation of the partition function from the quantum states of the horizon, appears to be hitherto absent. This work is an attempt to bridge this small, but essential, gap that appears to be present between the existing literature of quantum theory and thermodynamics of black holes. Further, it may be emphasized that this work is {\it only} concerned with the {\it metric independent} approaches to black hole thermodynamics. |
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