id stringlengths 9 13 | submitter stringlengths 1 64 ⌀ | authors stringlengths 5 22.9k | title stringlengths 4 245 | comments stringlengths 1 548 ⌀ | journal-ref stringlengths 4 362 ⌀ | doi stringlengths 12 82 ⌀ | report-no stringlengths 2 281 ⌀ | categories stringclasses 793 values | license stringclasses 9 values | orig_abstract stringlengths 24 1.95k | versions listlengths 1 30 | update_date stringlengths 10 10 | authors_parsed listlengths 1 1.74k | abstract stringlengths 21 1.95k |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
2312.11879 | Wei Xiong | Wei Xiong, Cheng-Yong Zhang, and Peng-Cheng Li | The rotating solutions beyond the spontaneous scalarization in
Einstein-Maxwell-scalar theory | 22 pages, 7 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Einstein-Maxwell-scalar (EMS) theory with a quartic coupling function
features three branches of fundamental black hole (BH) solutions, labeled as
cold, hot, and bald black holes. The static bald black holes (the
Reissner-Nordstr\"om BH) exhibit an intriguing nonlinear instability beyond the
spontaneous scalarization. We study the rotating scalarized black hole
solutions in the EMS model with a quartic coupling function through the
spectral method numerically. The domain of existence for the scalarized BHs is
presented in the spin-charge region. We found that the rotating solutions for
both the two scalarized branches possess similar thermodynamic behavior
compared to the static case while varying the electric charge. The BH spin
enlarges the thermodynamic differences between the cold and hot branches. The
profile of the metric function and the scalar field for the scalarized BHs is
depicted, which demonstrates that the scalar field concentrates more on the
equatorial plane in contrast to the axisymmetric region as the spin increases.
| [
{
"created": "Tue, 19 Dec 2023 06:13:48 GMT",
"version": "v1"
},
{
"created": "Wed, 24 Jan 2024 06:33:56 GMT",
"version": "v2"
}
] | 2024-01-25 | [
[
"Xiong",
"Wei",
""
],
[
"Zhang",
"Cheng-Yong",
""
],
[
"Li",
"Peng-Cheng",
""
]
] | The Einstein-Maxwell-scalar (EMS) theory with a quartic coupling function features three branches of fundamental black hole (BH) solutions, labeled as cold, hot, and bald black holes. The static bald black holes (the Reissner-Nordstr\"om BH) exhibit an intriguing nonlinear instability beyond the spontaneous scalarization. We study the rotating scalarized black hole solutions in the EMS model with a quartic coupling function through the spectral method numerically. The domain of existence for the scalarized BHs is presented in the spin-charge region. We found that the rotating solutions for both the two scalarized branches possess similar thermodynamic behavior compared to the static case while varying the electric charge. The BH spin enlarges the thermodynamic differences between the cold and hot branches. The profile of the metric function and the scalar field for the scalarized BHs is depicted, which demonstrates that the scalar field concentrates more on the equatorial plane in contrast to the axisymmetric region as the spin increases. |
1905.09968 | Valerio Faraoni | Jeremy C\^ot\'e, Valerio Faraoni, and Andrea Giusti | Revisiting the conformal invariance of Maxwell's equations in curved
spacetime | null | null | 10.1007/s10714-019-2599-x | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We revisit the invariance of the curved spacetime Maxwell equations under
conformal transformations. Contrary to standard literature, we include the
discussion of the four-current, the wave equations for the four-potential and
the field, and the behaviour of gauge conditions under the conformal
transformation.
| [
{
"created": "Thu, 23 May 2019 23:28:21 GMT",
"version": "v1"
}
] | 2019-09-25 | [
[
"Côté",
"Jeremy",
""
],
[
"Faraoni",
"Valerio",
""
],
[
"Giusti",
"Andrea",
""
]
] | We revisit the invariance of the curved spacetime Maxwell equations under conformal transformations. Contrary to standard literature, we include the discussion of the four-current, the wave equations for the four-potential and the field, and the behaviour of gauge conditions under the conformal transformation. |
gr-qc/9801099 | Ugo Moschella | Jacques Bros, Henri Epstein, Ugo Moschella | Analyticity properties and thermal effects for general quantum field
theory on de Sitter space-time | 32 pages, Latex. To appear on Commun. Math. Phys | Commun.Math.Phys. 196 (1998) 535-570 | 10.1007/s002200050435 | IHES-P-97-52 | gr-qc hep-th | null | We propose a general framework for quantum field theory on the de Sitter
space-time (i.e. for local field theories whose truncated Wightman functions
are not required to vanish). By requiring that the fields satisfy a weak
spectral condition, formulated in terms of the analytic continuation properties
of their Wightman functions, we show that a geodesical observer will detect in
the corresponding ``vacuum'' a blackbody radiation at temperature T=1/(2 \pi
R). We also prove the analogues of the PCT, Reeh-Schlieder and
Bisognano-Wichmann theorems.
| [
{
"created": "Thu, 29 Jan 1998 11:13:57 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Bros",
"Jacques",
""
],
[
"Epstein",
"Henri",
""
],
[
"Moschella",
"Ugo",
""
]
] | We propose a general framework for quantum field theory on the de Sitter space-time (i.e. for local field theories whose truncated Wightman functions are not required to vanish). By requiring that the fields satisfy a weak spectral condition, formulated in terms of the analytic continuation properties of their Wightman functions, we show that a geodesical observer will detect in the corresponding ``vacuum'' a blackbody radiation at temperature T=1/(2 \pi R). We also prove the analogues of the PCT, Reeh-Schlieder and Bisognano-Wichmann theorems. |
0804.0800 | Shantanu Desai | L. Blackburn, L. Cadonati, S. Caride, S. Caudill, S. Chatterji, N.
Christensen, J. Dalrymple, S. Desai, A. Di Credico, G. Ely, J. Garofoli, L.
Goggin, G. Gonz\'alez, R. Gouaty, C. Gray, A. Gretarsson, D. Hoak, T. Isogai,
E. Katsavounidis, J. Kissel, S. Klimenko, R.A. Mercer, S. Mohapatra, S.
Mukherjee, F. Raab, K. Riles, P. Saulson, R. Schofield, P. Shawhan, J.
Slutsky, J.R. Smith, R. Stone, C. Vorvick, M. Zanolin, N. Zotov, J. Zweizig | The LSC Glitch Group : Monitoring Noise Transients during the fifth LIGO
Science Run | 9 pages, 8 figures, Contribution to 12th Gravitational Wave Data
Analysis Workshop. Changes in response to referee comments. Accepted for
publication in CQG | Class.Quant.Grav.25:184004,2008 | 10.1088/0264-9381/25/18/184004 | LIGO-P080016-01 | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The LIGO Scientific Collaboration (LSC) glitch group is part of the LIGO
detector characterization effort. It consists of data analysts and detector
experts who, during and after science runs, collaborate for a better
understanding of noise transients in the detectors. Goals of the glitch group
during the fifth LIGO science run (S5) included (1) offline assessment of the
detector data quality, with focus on noise transients, (2) veto recommendations
for astrophysical analysis and (3) feedback to the commissioning team on
anomalies seen in gravitational wave and auxiliary data channels. Other
activities included the study of auto-correlation of triggers from burst
searches, stationarity of the detector noise and veto studies. The group
identified causes for several noise transients that triggered false alarms in
the gravitational wave searches; the times of such transients were identified
and vetoed from the data generating the LSC astrophysical results.
| [
{
"created": "Fri, 4 Apr 2008 20:00:35 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Jul 2008 22:14:20 GMT",
"version": "v2"
}
] | 2016-02-11 | [
[
"Blackburn",
"L.",
""
],
[
"Cadonati",
"L.",
""
],
[
"Caride",
"S.",
""
],
[
"Caudill",
"S.",
""
],
[
"Chatterji",
"S.",
""
],
[
"Christensen",
"N.",
""
],
[
"Dalrymple",
"J.",
""
],
[
"Desai",
... | The LIGO Scientific Collaboration (LSC) glitch group is part of the LIGO detector characterization effort. It consists of data analysts and detector experts who, during and after science runs, collaborate for a better understanding of noise transients in the detectors. Goals of the glitch group during the fifth LIGO science run (S5) included (1) offline assessment of the detector data quality, with focus on noise transients, (2) veto recommendations for astrophysical analysis and (3) feedback to the commissioning team on anomalies seen in gravitational wave and auxiliary data channels. Other activities included the study of auto-correlation of triggers from burst searches, stationarity of the detector noise and veto studies. The group identified causes for several noise transients that triggered false alarms in the gravitational wave searches; the times of such transients were identified and vetoed from the data generating the LSC astrophysical results. |
gr-qc/0009071 | Yuri Pavlov | A. A. Grib, Yu. V. Pavlov | On the possible role of superheavy particles in the early Universe | LaTeX, 7 pages | "I. Ya. Pomeranchuk and Physics at the Turn of the Century".
Proceedings of the International Conference. Eds. A.Berkov, N.Narozhny,
L.Okun. World Scientific Publ., Singapore, 2003, pp.406-412 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Different models of the role of creation of superheavy particles in the early
Friedmann Universe with their subsequent decay on light particles are
investigated. The observable numbers of baryon and entropy are predicted. The
possible role of superheavy particles in creation of cold dark matter is
discussed.
| [
{
"created": "Wed, 20 Sep 2000 18:55:41 GMT",
"version": "v1"
},
{
"created": "Thu, 10 Feb 2011 18:55:40 GMT",
"version": "v2"
}
] | 2011-02-11 | [
[
"Grib",
"A. A.",
""
],
[
"Pavlov",
"Yu. V.",
""
]
] | Different models of the role of creation of superheavy particles in the early Friedmann Universe with their subsequent decay on light particles are investigated. The observable numbers of baryon and entropy are predicted. The possible role of superheavy particles in creation of cold dark matter is discussed. |
1705.06294 | Michael Florian Wondrak | Michael Florian Wondrak | The Cosmological Constant and its Problems: A Review of Gravitational
Aether | 10 pages, 2 figures. To appear in the collection of the fifth
international conference on "Experimental Search for Quantum Gravity", held
at FIAS, Frankfurt am Main (Germany), 19-23 September 2016, Springer | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this essay we offer a comprehensible overview of the gravitational aether
scenario. This is a possible extension of Einstein's theory of relativity to
the quantum regime via an effective approach. Quantization of gravity usually
faces several issues including an unexpected high vacuum energy density caused
by quantum fluctuations. The model presented in this paper offers a solution to
the so-called cosmological constant problems.
As its name suggests, the gravitational aether introduces preferred reference
frames, while it remains compatible with the general theory of relativity. As a
rare feature among quantum gravity inspired theories, it can predict measurable
astronomical and cosmological effects. Observational data disfavor the
gravitational aether scenario at $2.6\text{-}5\,\sigma$. This experimental
feedback gives rise to possible refinements of the theory.
| [
{
"created": "Wed, 17 May 2017 18:00:39 GMT",
"version": "v1"
}
] | 2017-05-19 | [
[
"Wondrak",
"Michael Florian",
""
]
] | In this essay we offer a comprehensible overview of the gravitational aether scenario. This is a possible extension of Einstein's theory of relativity to the quantum regime via an effective approach. Quantization of gravity usually faces several issues including an unexpected high vacuum energy density caused by quantum fluctuations. The model presented in this paper offers a solution to the so-called cosmological constant problems. As its name suggests, the gravitational aether introduces preferred reference frames, while it remains compatible with the general theory of relativity. As a rare feature among quantum gravity inspired theories, it can predict measurable astronomical and cosmological effects. Observational data disfavor the gravitational aether scenario at $2.6\text{-}5\,\sigma$. This experimental feedback gives rise to possible refinements of the theory. |
2402.08630 | Martiros Khurshudyan | Martiros Khurshudyan and Emilio Elizalde | Constraints on prospective deviations from the cold dark matter model
using a Gaussian Process | 15 pages | null | null | null | gr-qc astro-ph.CO hep-ph hep-th | http://creativecommons.org/licenses/by/4.0/ | Recently, using Bayesian Machine Learning, a deviation from the cold dark
matter model on cosmological scales has been put forward. Such model might
replace a proposed non-gravitational interaction between dark energy and dark
matter, and help solve the $H_{0}$ tension problem. The idea behind the
learning procedure relied there on a generated expansion rate, while the real
expansion rate was just used to validate the learned results. In the present
work, however, the emphasis is put on a Gaussian Process (GP) with the
available $H(z)$ data confirming the possible existence of the already learned
deviation. Three cosmological scenarios are considered: a simple one, with
equation of state parameter for dark matter $\omega_{dm} = \omega_{0} \neq 0$,
and two other models, with corresponding parameters $\omega_{dm} = \omega_{0} +
\omega_{1} z$ and $\omega_{dm} = \omega_{0} + \omega_{1} z/(1+z)$. The
constraints obtained on the free parameters $\omega_{0}$ and $\omega_{1}$ hint
towards a dynamical nature of the deviation. The dark energy dynamics is also
reconstructed, revealing interesting aspects connected with the $H_{0}$ tension
problem. It is concluded, however, that improved tools and more data are
needed, in order to reach a better understanding of the reported deviation.
| [
{
"created": "Fri, 19 Jan 2024 10:56:17 GMT",
"version": "v1"
}
] | 2024-02-14 | [
[
"Khurshudyan",
"Martiros",
""
],
[
"Elizalde",
"Emilio",
""
]
] | Recently, using Bayesian Machine Learning, a deviation from the cold dark matter model on cosmological scales has been put forward. Such model might replace a proposed non-gravitational interaction between dark energy and dark matter, and help solve the $H_{0}$ tension problem. The idea behind the learning procedure relied there on a generated expansion rate, while the real expansion rate was just used to validate the learned results. In the present work, however, the emphasis is put on a Gaussian Process (GP) with the available $H(z)$ data confirming the possible existence of the already learned deviation. Three cosmological scenarios are considered: a simple one, with equation of state parameter for dark matter $\omega_{dm} = \omega_{0} \neq 0$, and two other models, with corresponding parameters $\omega_{dm} = \omega_{0} + \omega_{1} z$ and $\omega_{dm} = \omega_{0} + \omega_{1} z/(1+z)$. The constraints obtained on the free parameters $\omega_{0}$ and $\omega_{1}$ hint towards a dynamical nature of the deviation. The dark energy dynamics is also reconstructed, revealing interesting aspects connected with the $H_{0}$ tension problem. It is concluded, however, that improved tools and more data are needed, in order to reach a better understanding of the reported deviation. |
gr-qc/0003026 | Naresh Dadhich | Naresh Dadhich | On product spacetime with 2-sphere of constant curvature | 9 pages, 1 figure, LaTex version | null | null | IUCAA-10/2000 | gr-qc | null | If we consider the spacetime manifold as product of a constant curvature
2-sphere (hypersphere) and a 2-space, then solution of the Einstein equation
requires that the latter must also be of constant curvature. There exist only
two solutions for classical matter distribution which are given by the Nariai
(anti) metric describing an Einstein space and the Bertotti - Robinson (anti)
metric describing a uniform electric field. These two solutions are
transformable into each other by letting the timelike convergence density
change sign. The hyperspherical solution is anti of the spherical one and the
vice -versa. For non classical matter, we however find a new solution, which is
electrograv dual to the flat space, and describes a cloud of string dust of
uniform energy density. We also discuss some interesting features of the
particle motion in the Bertotti - Robinson metric.
| [
{
"created": "Wed, 8 Mar 2000 06:24:16 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Dadhich",
"Naresh",
""
]
] | If we consider the spacetime manifold as product of a constant curvature 2-sphere (hypersphere) and a 2-space, then solution of the Einstein equation requires that the latter must also be of constant curvature. There exist only two solutions for classical matter distribution which are given by the Nariai (anti) metric describing an Einstein space and the Bertotti - Robinson (anti) metric describing a uniform electric field. These two solutions are transformable into each other by letting the timelike convergence density change sign. The hyperspherical solution is anti of the spherical one and the vice -versa. For non classical matter, we however find a new solution, which is electrograv dual to the flat space, and describes a cloud of string dust of uniform energy density. We also discuss some interesting features of the particle motion in the Bertotti - Robinson metric. |
gr-qc/0110091 | Kashif Alvi | Kashif Alvi, Yuk Tung Liu | On the tidally induced gravitational collapse of a particle cluster | 8 pages, 5 figures | Gen.Rel.Grav. 34 (2002) 1067-1076 | 10.1023/A:1016514021408 | null | gr-qc | null | An important issue in the dynamics of neutron star binaries is whether tidal
interaction can cause the individual stars to collapse into black holes during
inspiral. To understand this issue better, we study the dynamics of a cluster
of collisionless particles orbiting a non-rotating black hole, which is part of
a widely separated circular binary. The companion body's electric- and
magnetic-type tidal fields distort the black hole and perturb the cluster,
eventually causing the cluster to collapse into the hole as the companion
spirals in under the influence of gravitational radiation reaction. We find
that magnetic-type tidal forces do not significantly influence the evolution of
the cluster as a whole. However, individual orbits can be strongly affected by
these forces. For example, some orbits are destabilized due to the addition of
magnetic-type tidal forces. We find that the most stable orbits are close to
the companion's orbital plane and retrograde with respect to the companion's
orbit.
| [
{
"created": "Mon, 22 Oct 2001 21:40:20 GMT",
"version": "v1"
}
] | 2021-10-20 | [
[
"Alvi",
"Kashif",
""
],
[
"Liu",
"Yuk Tung",
""
]
] | An important issue in the dynamics of neutron star binaries is whether tidal interaction can cause the individual stars to collapse into black holes during inspiral. To understand this issue better, we study the dynamics of a cluster of collisionless particles orbiting a non-rotating black hole, which is part of a widely separated circular binary. The companion body's electric- and magnetic-type tidal fields distort the black hole and perturb the cluster, eventually causing the cluster to collapse into the hole as the companion spirals in under the influence of gravitational radiation reaction. We find that magnetic-type tidal forces do not significantly influence the evolution of the cluster as a whole. However, individual orbits can be strongly affected by these forces. For example, some orbits are destabilized due to the addition of magnetic-type tidal forces. We find that the most stable orbits are close to the companion's orbital plane and retrograde with respect to the companion's orbit. |
0801.2750 | Hiroyuki Nakano | Hiroyuki Nakano, Carlos O. Lousto (RIT) | New method to integrate 2+1 wave equations with Dirac's delta functions
as sources | 4 pages, 1 figure, prepared for the proceedings of the 17th workshop
on general relativity and gravitation, Nagoya, Japan, Dec.3 - Dec.7, 2007 | null | null | null | gr-qc | null | Gravitational perturbations in a Kerr black hole background can not be
decomposed into simple tensor harmonics in the time domain. Here, we make the
mode decomposition only in the azimuthal direction and discuss the resulting
(2+1)-dimensional Klein-Gordon differential equation for scalar perturbations
with a two dimensional Dirac's $\delta$-function as a source representing a
point particle orbiting a much larger black hole. To make this equation
amenable for numerical integrations we explicitly remove analytically the
singular behavior of the source and compute a global effective source for the
corresponding waveform.
| [
{
"created": "Thu, 17 Jan 2008 19:15:07 GMT",
"version": "v1"
}
] | 2008-01-18 | [
[
"Nakano",
"Hiroyuki",
"",
"RIT"
],
[
"Lousto",
"Carlos O.",
"",
"RIT"
]
] | Gravitational perturbations in a Kerr black hole background can not be decomposed into simple tensor harmonics in the time domain. Here, we make the mode decomposition only in the azimuthal direction and discuss the resulting (2+1)-dimensional Klein-Gordon differential equation for scalar perturbations with a two dimensional Dirac's $\delta$-function as a source representing a point particle orbiting a much larger black hole. To make this equation amenable for numerical integrations we explicitly remove analytically the singular behavior of the source and compute a global effective source for the corresponding waveform. |
gr-qc/0309012 | Andreas Freise | A. Freise, G. Heinzel, H. Lueck, R. Schilling, B. Willke and K.
Danzmann | Frequency domain interferometer simulation with higher-order spatial
modes | Added an example for the application of the simulation during the
commisioning of the GEO 600 gravitational-wave detector | Class.Quant.Grav. 21 (2004) S1067-S1074 | 10.1088/0264-9381/21/5/102 | null | gr-qc | null | FINESSE is a software simulation that allows to compute the optical
properties of laser interferometers as they are used by the interferometric
gravitational-wave detectors today. It provides a fast and versatile tool which
has proven to be very useful during the design and the commissioning of
gravitational-wave detectors. The basic algorithm of FINESSE numerically
computes the light amplitudes inside an interferometer using Hermite-Gauss
modes in the frequency domain. In addition, FINESSE provides a number of
commands to easily generate and plot the most common signals like, for example,
power enhancement, error or control signals, transfer functions and
shot-noise-limited sensitivities.
Among the various simulation tools available to the gravitational wave
community today, FINESSE is the most advanced general optical simulation that
uses the frequency domain. It has been designed to allow general analysis of
user defined optical setups while being easy to install and easy to use.
| [
{
"created": "Tue, 2 Sep 2003 15:11:30 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Jan 2004 16:32:38 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Freise",
"A.",
""
],
[
"Heinzel",
"G.",
""
],
[
"Lueck",
"H.",
""
],
[
"Schilling",
"R.",
""
],
[
"Willke",
"B.",
""
],
[
"Danzmann",
"K.",
""
]
] | FINESSE is a software simulation that allows to compute the optical properties of laser interferometers as they are used by the interferometric gravitational-wave detectors today. It provides a fast and versatile tool which has proven to be very useful during the design and the commissioning of gravitational-wave detectors. The basic algorithm of FINESSE numerically computes the light amplitudes inside an interferometer using Hermite-Gauss modes in the frequency domain. In addition, FINESSE provides a number of commands to easily generate and plot the most common signals like, for example, power enhancement, error or control signals, transfer functions and shot-noise-limited sensitivities. Among the various simulation tools available to the gravitational wave community today, FINESSE is the most advanced general optical simulation that uses the frequency domain. It has been designed to allow general analysis of user defined optical setups while being easy to install and easy to use. |
1309.2004 | William C. C. Lima | William C. C. Lima | Quantization of unstable linear scalar fields in static spacetimes | 14 pages. Rectification of the statement at the end of the Sec. III B
of the published version. All other results unchanged | Phys. Rev. D 88, 124005 (2013); Erratum 94, 129901(E) (2016) | 10.1103/PhysRevD.88.124005 10.1103/PhysRevD.94.129901 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss the quantization of an unstable field through the construction of
a "one-particle Hilbert space." The system considered here is a neutral scalar
field evolving over a globally hyperbolic static spacetime and subject to a
stationary external scalar potential. In order to prove our results we assume
spacetimes without horizons and that the theory possess a "mass gap." Our
strategy consists in building a complex structure, which arises from a suitable
positive bilinear form defined over the space of classical solutions of the
field equation. Once the space of states of the quantum field has been set, it
is possible to study the effect of the time translation symmetry on it. From
the time translation operator we obtain an expression for the Hamiltonian
operator associated with the unstable sector of the field. This last result
coincides with findings from long ago showing that the unstable degrees of
freedom of the field behave as non-relativistic particles in a parabolic
potential barrier.
| [
{
"created": "Sun, 8 Sep 2013 20:18:26 GMT",
"version": "v1"
},
{
"created": "Fri, 8 Nov 2013 13:37:05 GMT",
"version": "v2"
},
{
"created": "Tue, 3 Dec 2013 16:46:44 GMT",
"version": "v3"
},
{
"created": "Wed, 11 Jan 2017 16:59:51 GMT",
"version": "v4"
}
] | 2017-01-12 | [
[
"Lima",
"William C. C.",
""
]
] | We discuss the quantization of an unstable field through the construction of a "one-particle Hilbert space." The system considered here is a neutral scalar field evolving over a globally hyperbolic static spacetime and subject to a stationary external scalar potential. In order to prove our results we assume spacetimes without horizons and that the theory possess a "mass gap." Our strategy consists in building a complex structure, which arises from a suitable positive bilinear form defined over the space of classical solutions of the field equation. Once the space of states of the quantum field has been set, it is possible to study the effect of the time translation symmetry on it. From the time translation operator we obtain an expression for the Hamiltonian operator associated with the unstable sector of the field. This last result coincides with findings from long ago showing that the unstable degrees of freedom of the field behave as non-relativistic particles in a parabolic potential barrier. |
1612.05751 | Ehsan Sadri | Ehsan Sadri | An analysis of the expansion acceleration of the Universe in the
Interacting Holographic Dark Energy model | Repetitive work. It has been worked by other author before. A sheykhi | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Holographic model is originated from Holographic principle. The equation of
state in Holographic model and Einstein's gravity with particle horizon can be
obtained as wD>-1/3 and cannot justify the expansion acceleration of the
Universe. But, by using the event horizon, this model can result in the
accelerating expansion in Einstein's gravity and Brans-Dicke cosmology. In this
context, we study the holographic model with apparent horizon satisfying the
acceleration expansion. We shall see, in the presence of interaction, phase
change and transition from decelerated state to accelerated state is possible.
This shows the sign of deceleration parameter.
| [
{
"created": "Sat, 17 Dec 2016 13:14:49 GMT",
"version": "v1"
},
{
"created": "Sun, 25 Jun 2017 20:44:45 GMT",
"version": "v2"
}
] | 2017-06-27 | [
[
"Sadri",
"Ehsan",
""
]
] | Holographic model is originated from Holographic principle. The equation of state in Holographic model and Einstein's gravity with particle horizon can be obtained as wD>-1/3 and cannot justify the expansion acceleration of the Universe. But, by using the event horizon, this model can result in the accelerating expansion in Einstein's gravity and Brans-Dicke cosmology. In this context, we study the holographic model with apparent horizon satisfying the acceleration expansion. We shall see, in the presence of interaction, phase change and transition from decelerated state to accelerated state is possible. This shows the sign of deceleration parameter. |
2111.02663 | Hamid R. Bakhtiarizadeh | Hamid R. Bakhtiarizadeh | Charged rotating black strings in Einsteinian cubic gravity | 16 pages, LaTex file, no figure, matches published version in PRD | null | 10.1103/PhysRevD.105.064037 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We construct, for the first time, charged rotating black string solutions in
four-dimensional Einsteinian cubic gravity, which are asymptotically anti de
Sitter. By assuming that the solutions are completely regular at the horizon
and studying their near-horizon behavior, we find some thermodynamic
properties, which can be accessed analytically. We compute independently the
Hawking temperature, the Wald entropy, the mass, the angular momentum, the
charge, and the electrostatic potential of the solutions, analytically. Using
these, we show that the first law of thermodynamics for rotating black strings
is exactly satisfied in both charged and uncharged cases. We also observe that,
in the absence of Maxwell field, some of the solutions have positive specific
heat, which makes them thermodynamically stable.
| [
{
"created": "Thu, 4 Nov 2021 07:06:12 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Mar 2022 17:11:50 GMT",
"version": "v2"
},
{
"created": "Wed, 23 Mar 2022 15:24:06 GMT",
"version": "v3"
}
] | 2022-03-24 | [
[
"Bakhtiarizadeh",
"Hamid R.",
""
]
] | We construct, for the first time, charged rotating black string solutions in four-dimensional Einsteinian cubic gravity, which are asymptotically anti de Sitter. By assuming that the solutions are completely regular at the horizon and studying their near-horizon behavior, we find some thermodynamic properties, which can be accessed analytically. We compute independently the Hawking temperature, the Wald entropy, the mass, the angular momentum, the charge, and the electrostatic potential of the solutions, analytically. Using these, we show that the first law of thermodynamics for rotating black strings is exactly satisfied in both charged and uncharged cases. We also observe that, in the absence of Maxwell field, some of the solutions have positive specific heat, which makes them thermodynamically stable. |
0804.4801 | Ujjal Debnath | Writambhara Chakraborty and Ujjal Debnath | Role of Tachyonic Field in Accelerating Universe in Presence of Perfect
Fluid | 9 latex pages, 4 figures, RevTex style | Astrophys.SpaceSci.315:73-78,2008 | 10.1007/s10509-008-9795-6 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently tachyonic field has been depicted as dark energy model to represent
the present acceleration of the Universe. In this paper we have considered
mixture of tachyonic fluid with a perfect fluid. For this purpose we have
considered barotropic fluid and Generalized Chaplygin gas(G.C.G.). We have
considered a particular form of the scale factor. We have solved the equations
of motion to get the exact solutions of the density, tachyonic potential and
the tachyonic field. We have introduced a coupling term to show that the
interaction decays with time. Also we have shown that the nature of the
potentials vary so as the interaction term reduces the potential in both the
cases.
| [
{
"created": "Wed, 30 Apr 2008 11:56:13 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Chakraborty",
"Writambhara",
""
],
[
"Debnath",
"Ujjal",
""
]
] | Recently tachyonic field has been depicted as dark energy model to represent the present acceleration of the Universe. In this paper we have considered mixture of tachyonic fluid with a perfect fluid. For this purpose we have considered barotropic fluid and Generalized Chaplygin gas(G.C.G.). We have considered a particular form of the scale factor. We have solved the equations of motion to get the exact solutions of the density, tachyonic potential and the tachyonic field. We have introduced a coupling term to show that the interaction decays with time. Also we have shown that the nature of the potentials vary so as the interaction term reduces the potential in both the cases. |
2405.11583 | Muchun Chen | Mu-Chun Chen, Hao-Yang Liu, Qi-Yan Zhang, Jun Zhang | Probing Massive Fields with Multi-Band Gravitational-Wave Observations | 8 pages,3 figures | null | null | null | gr-qc astro-ph.CO hep-ex hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the prospect of probing massive fields and testing
gravitational theories with multi-band observations of gravitational waves
emitted from coalescing compact binaries. Focusing on the dipole radiation
induced by a massive field, we show that multi-band observations can probe the
field with mass ranging from $10^{-16}$ eV to $10^{-15}$ eV, a parameter space
that cannot be probed by the milli-Hertz band observations alone. Multi-band
observations can also improve the constraints obtained with the
LIGO-Virgo-KAGRA binaries by up to 3 orders of magnitude in the mass range.
Moreover, we show that multi-band observations can discriminate the spin of the
field, which cannot be identified with single-band observations.
| [
{
"created": "Sun, 19 May 2024 15:26:04 GMT",
"version": "v1"
},
{
"created": "Tue, 21 May 2024 05:57:05 GMT",
"version": "v2"
}
] | 2024-05-22 | [
[
"Chen",
"Mu-Chun",
""
],
[
"Liu",
"Hao-Yang",
""
],
[
"Zhang",
"Qi-Yan",
""
],
[
"Zhang",
"Jun",
""
]
] | We investigate the prospect of probing massive fields and testing gravitational theories with multi-band observations of gravitational waves emitted from coalescing compact binaries. Focusing on the dipole radiation induced by a massive field, we show that multi-band observations can probe the field with mass ranging from $10^{-16}$ eV to $10^{-15}$ eV, a parameter space that cannot be probed by the milli-Hertz band observations alone. Multi-band observations can also improve the constraints obtained with the LIGO-Virgo-KAGRA binaries by up to 3 orders of magnitude in the mass range. Moreover, we show that multi-band observations can discriminate the spin of the field, which cannot be identified with single-band observations. |
1801.06536 | Manuel Hohmann | Manuel Hohmann, Christian Pfeifer | Scalar-torsion theories of gravity II: $L(T, X, Y, \phi)$ theory | 14 pages, no figures | Phys. Rev. D 98, 064003 (2018) | 10.1103/PhysRevD.98.064003 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider Lorentz invariant scalar-tensor teleparallel gravity theories
with a Lagrangian built from the torsion scalar, a scalar field, its kinetic
term and a derivative coupling between the torsion and the scalar field. The
field equations of the theory are derived and the relation between the spin
connection and the antisymmetric part of the tetrad field equations is found
explicitly, which is an important consistency result for Lorentz invariant
teleparallel theories of gravity. Afterwards we study the behaviour of this
class of theories under conformal transformations and find that such
transformations map different theories in this class onto each other.
| [
{
"created": "Fri, 19 Jan 2018 18:57:00 GMT",
"version": "v1"
},
{
"created": "Wed, 28 Feb 2018 18:23:06 GMT",
"version": "v2"
}
] | 2018-09-12 | [
[
"Hohmann",
"Manuel",
""
],
[
"Pfeifer",
"Christian",
""
]
] | We consider Lorentz invariant scalar-tensor teleparallel gravity theories with a Lagrangian built from the torsion scalar, a scalar field, its kinetic term and a derivative coupling between the torsion and the scalar field. The field equations of the theory are derived and the relation between the spin connection and the antisymmetric part of the tetrad field equations is found explicitly, which is an important consistency result for Lorentz invariant teleparallel theories of gravity. Afterwards we study the behaviour of this class of theories under conformal transformations and find that such transformations map different theories in this class onto each other. |
1902.06903 | Shibaji Banerjee | Ashadul Halder, Shibaji Banerjee, Debasish Majumdar | Intensification of Gravitational Wave Field Near Compact Star | Total 10 pages, 6 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The gravitational waves (GWs) has been a topic of interest for its versatile
capabilities of probing several aspects of cosmology and early Universe.
Gravitational lensing enhances further the extent of this sort of waves and
upgrade our understanding to a next level. Besides several similarities with
optical waves, GWs are capable of passing through optically opaque celestial
objects like stars, exoplanets unlike light waves and manifest a different kind
of lensing effect. In this work we have explored the lensing action of compact
objects on gravitational waves using numerical means. After modeling the
internal mass distribution of the compact objects by TOV equations and tracing
wavefronts using geodesic equations, we have found that the GWs are indeed
lensed in a manner analogous to the optical lensing of light in presence of a
thick optical lens by producing spherical aberration in the focused waves. The
distance to the best focused point shows significant dependence with the mass
and radius of the lensing star and unlike gravitational lensing, the region
inside and outside compact objects responds differently to the incoming waves.
| [
{
"created": "Tue, 19 Feb 2019 05:31:52 GMT",
"version": "v1"
}
] | 2019-02-20 | [
[
"Halder",
"Ashadul",
""
],
[
"Banerjee",
"Shibaji",
""
],
[
"Majumdar",
"Debasish",
""
]
] | The gravitational waves (GWs) has been a topic of interest for its versatile capabilities of probing several aspects of cosmology and early Universe. Gravitational lensing enhances further the extent of this sort of waves and upgrade our understanding to a next level. Besides several similarities with optical waves, GWs are capable of passing through optically opaque celestial objects like stars, exoplanets unlike light waves and manifest a different kind of lensing effect. In this work we have explored the lensing action of compact objects on gravitational waves using numerical means. After modeling the internal mass distribution of the compact objects by TOV equations and tracing wavefronts using geodesic equations, we have found that the GWs are indeed lensed in a manner analogous to the optical lensing of light in presence of a thick optical lens by producing spherical aberration in the focused waves. The distance to the best focused point shows significant dependence with the mass and radius of the lensing star and unlike gravitational lensing, the region inside and outside compact objects responds differently to the incoming waves. |
gr-qc/0307070 | Viqar Husain | Viqar Husain | Probing entropy bounds with scalar field spacetimes | 10 pages, 5 figures; published version with typos corrected | Phys.Rev. D69 (2004) 084002 | 10.1103/PhysRevD.69.084002 | null | gr-qc hep-th | null | We study covariant entropy bounds in dynamical spacetimes with naked
singularities. Specifically we study a spherically symmetric massless scalar
field solution. The solution is an inhomogeneous cosmology with an initial
spacelike singularity, and a naked timelike singularity at the origin. We
construct the entropy flux 4-vector for the scalar field, and show by explicit
computation that the generalized covariant bound $S_{L(B,B')}\le (A(B)-A(B'))/4
$ is violated for light sheets $L(B,B')$ in the neighbourhood of the (evolving)
apparent horizon. We find no violations of the Bousso bound (for which
$A(B')=0$), even though certain sufficient conditions for this bound do not
hold. This result therefore shows that these conditions are not necessary.
| [
{
"created": "Tue, 15 Jul 2003 19:47:49 GMT",
"version": "v1"
},
{
"created": "Wed, 31 Dec 2003 18:44:38 GMT",
"version": "v2"
},
{
"created": "Wed, 2 Jun 2004 19:46:41 GMT",
"version": "v3"
}
] | 2009-11-10 | [
[
"Husain",
"Viqar",
""
]
] | We study covariant entropy bounds in dynamical spacetimes with naked singularities. Specifically we study a spherically symmetric massless scalar field solution. The solution is an inhomogeneous cosmology with an initial spacelike singularity, and a naked timelike singularity at the origin. We construct the entropy flux 4-vector for the scalar field, and show by explicit computation that the generalized covariant bound $S_{L(B,B')}\le (A(B)-A(B'))/4 $ is violated for light sheets $L(B,B')$ in the neighbourhood of the (evolving) apparent horizon. We find no violations of the Bousso bound (for which $A(B')=0$), even though certain sufficient conditions for this bound do not hold. This result therefore shows that these conditions are not necessary. |
gr-qc/0502082 | Kevin Vandersloot | Kevin Vandersloot | On the Hamiltonian Constraint of Loop Quantum Cosmology | null | Phys.Rev. D71 (2005) 103506 | 10.1103/PhysRevD.71.103506 | null | gr-qc | null | In this paper we construct the Hamiltonian constraint operator of loop
quantum cosmology using holonomies defined for arbitrary irreducible SU(2)
representations labeled by spin J. We show that modifications to the effective
semi-classical equations of motion arise both in the gravitational part of the
constraint as well as matter terms. The modifications are important for
phenomenological investigations of the cosmological imprints of loop quantum
cosmology. We discuss the implications for the early universe evolution.
| [
{
"created": "Sun, 20 Feb 2005 17:53:36 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Vandersloot",
"Kevin",
""
]
] | In this paper we construct the Hamiltonian constraint operator of loop quantum cosmology using holonomies defined for arbitrary irreducible SU(2) representations labeled by spin J. We show that modifications to the effective semi-classical equations of motion arise both in the gravitational part of the constraint as well as matter terms. The modifications are important for phenomenological investigations of the cosmological imprints of loop quantum cosmology. We discuss the implications for the early universe evolution. |
1005.5347 | Sergio Dain | Sergio Dain and Mart\'in Reiris | Linear perturbations for the vacuum axisymmetric Einstein equations | 13 pages. We suppressed the statements about decay at infinity. The
proofs of these statements were incomplete. The complete proofs will require
extensive technical analysis. We will studied this in a subsequent work. We
also have rewritten the introduction and slighted changed the title | Annales Henri Poincare 12:49-65,2011 | 10.1007/s00023-010-0074-z | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In axial symmetry, there is a gauge for Einstein equations such that the
total mass of the spacetime can be written as a conserved, positive definite,
integral on the spacelike slices. This property is expected to play an
important role in the global evolution. In this gauge the equations reduce to a
coupled hyperbolic-elliptic system which is formally singular at the axis. Due
to the rather peculiar properties of the system, the local in time existence
has proved to resist analysis by standard methods. To analyze the principal
part of the equations, which may represent the main source of the difficulties,
we study linear perturbation around the flat Minkowski solution in this gauge.
In this article we solve this linearized system explicitly in terms of integral
transformations in a remarkable simple form. This representation is well suited
to obtain useful estimates to apply in the non-linear case.
| [
{
"created": "Fri, 28 May 2010 18:02:43 GMT",
"version": "v1"
},
{
"created": "Wed, 28 Jul 2010 13:34:59 GMT",
"version": "v2"
}
] | 2011-02-01 | [
[
"Dain",
"Sergio",
""
],
[
"Reiris",
"Martín",
""
]
] | In axial symmetry, there is a gauge for Einstein equations such that the total mass of the spacetime can be written as a conserved, positive definite, integral on the spacelike slices. This property is expected to play an important role in the global evolution. In this gauge the equations reduce to a coupled hyperbolic-elliptic system which is formally singular at the axis. Due to the rather peculiar properties of the system, the local in time existence has proved to resist analysis by standard methods. To analyze the principal part of the equations, which may represent the main source of the difficulties, we study linear perturbation around the flat Minkowski solution in this gauge. In this article we solve this linearized system explicitly in terms of integral transformations in a remarkable simple form. This representation is well suited to obtain useful estimates to apply in the non-linear case. |
gr-qc/0109030 | W. M. Stuckey | W.M. Stuckey | Metric structure and dimensionality over a Borel set via uniform spaces | 12 pages, 1 figure; references added | null | null | null | gr-qc | null | We introduce a pregeometry that provides a metric and dimensionality over a
Borel set (Wheeler's "bucket of dust") without assuming probability amplitudes
for adjacency. Rather, a non-trivial metric is produced over a Borel set X per
a uniformity base generated via the discrete topological group structures over
X. We show that entourage multiplication in this uniformity base mirrors the
underlying group structure. One may exploit this fact to create an entourage
sequence of maximal length whence a fine metric structure. Unlike the
statistical approaches of graph theory, this method can suggest dimensionality
over low-order sets. An example over Z2 x Z4 produces 3-dimensional polyhedra
embedded in E4.
| [
{
"created": "Mon, 10 Sep 2001 14:40:39 GMT",
"version": "v1"
},
{
"created": "Tue, 25 Sep 2001 16:47:49 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Stuckey",
"W. M.",
""
]
] | We introduce a pregeometry that provides a metric and dimensionality over a Borel set (Wheeler's "bucket of dust") without assuming probability amplitudes for adjacency. Rather, a non-trivial metric is produced over a Borel set X per a uniformity base generated via the discrete topological group structures over X. We show that entourage multiplication in this uniformity base mirrors the underlying group structure. One may exploit this fact to create an entourage sequence of maximal length whence a fine metric structure. Unlike the statistical approaches of graph theory, this method can suggest dimensionality over low-order sets. An example over Z2 x Z4 produces 3-dimensional polyhedra embedded in E4. |
1511.00225 | Alexander Pavlov E | Alexander E. Pavlov | Intrinsic time in Wheeler-DeWitt conformal superspace | 12 pages | null | 10.1142/9789814759816_0047 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An intrinsic time in Geometrodynamics is obtained with using a scaled Dirac's
mapping. By addition of a background metric, one can construct a scalar field.
It is suitable to play a role of intrinsic time. Cauchy problem was
successfully solved in conformal variables because they are physical ones.
First, the intrinsic time as a logarithm of determinant of spatial metric, was
applied to a cosmological problem by Misner. A global time is exist under
condition of constant mean curvature slicing of spacetime. The volume of
hypersurface and so-called mean York's time are canonical conjugated pair. So,
the volume is the intrinsic global time by its sense. The experimentally
observed redshift in cosmology is the evidence of its existence.
| [
{
"created": "Sun, 1 Nov 2015 10:30:08 GMT",
"version": "v1"
},
{
"created": "Sun, 29 May 2016 16:00:14 GMT",
"version": "v2"
}
] | 2016-05-31 | [
[
"Pavlov",
"Alexander E.",
""
]
] | An intrinsic time in Geometrodynamics is obtained with using a scaled Dirac's mapping. By addition of a background metric, one can construct a scalar field. It is suitable to play a role of intrinsic time. Cauchy problem was successfully solved in conformal variables because they are physical ones. First, the intrinsic time as a logarithm of determinant of spatial metric, was applied to a cosmological problem by Misner. A global time is exist under condition of constant mean curvature slicing of spacetime. The volume of hypersurface and so-called mean York's time are canonical conjugated pair. So, the volume is the intrinsic global time by its sense. The experimentally observed redshift in cosmology is the evidence of its existence. |
1607.08333 | Bibhas Majhi Ranjan | Ashish Bakshi, Bibhas Ranjan Majhi, Saurav Samanta | Gravitational surface Hamiltonian and entropy quantization | Revised version, accepted in Phys. Lett. B | Phys.Lett. B765 (2017) 334-338 | 10.1016/j.physletb.2016.12.036 | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The surface Hamiltonian corresponding to the surface part of a gravitational
action has $xp$ structure where $p$ is conjugate momentum of $x$. Moreover, it
leads to $TS$ on the horizon of a black hole. Here $T$ and $S$ are temperature
and entropy of the horizon. Imposing the hermiticity condition we quantize this
Hamiltonian. This leads to an equidistant spectrum of its eigenvalues. Using
this we show that the entropy of the horizon is quantized. This analysis holds
for any order of Lanczos-Lovelock gravity. For general relativity, the area
spectrum is consistent with Bekenstein's observation. This provides a more
robust confirmation of this earlier result as the calculation is based on the
direct quantization of the Hamiltonian in the sense of usual quantum mechanics.
| [
{
"created": "Thu, 28 Jul 2016 07:27:01 GMT",
"version": "v1"
},
{
"created": "Wed, 28 Dec 2016 07:21:31 GMT",
"version": "v2"
}
] | 2016-12-30 | [
[
"Bakshi",
"Ashish",
""
],
[
"Majhi",
"Bibhas Ranjan",
""
],
[
"Samanta",
"Saurav",
""
]
] | The surface Hamiltonian corresponding to the surface part of a gravitational action has $xp$ structure where $p$ is conjugate momentum of $x$. Moreover, it leads to $TS$ on the horizon of a black hole. Here $T$ and $S$ are temperature and entropy of the horizon. Imposing the hermiticity condition we quantize this Hamiltonian. This leads to an equidistant spectrum of its eigenvalues. Using this we show that the entropy of the horizon is quantized. This analysis holds for any order of Lanczos-Lovelock gravity. For general relativity, the area spectrum is consistent with Bekenstein's observation. This provides a more robust confirmation of this earlier result as the calculation is based on the direct quantization of the Hamiltonian in the sense of usual quantum mechanics. |
1306.1363 | Niall \'O Murchadha | Rory Conboye and Niall \'O Murchadha | Potentials for transverse trace-free tensors | null | Class. Quantum Grav. 31 (2014) 085019 | 10.1088/0264-9381/31/8/085019 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the initial conditions of the $3 + 1$ formalism for numerical relativity,
the transverse and trace-free (TT) part of the extrinsic curvature plays a key
role. We know that TT tensors possess two degrees of freedom per space point.
However, finding an expression for a TT tensor depending on only two scalar
functions is a non-trivial task. Assuming either axial or translational
symmetry, expressions depending on two scalar potentials alone are derived here
for \emph{all} TT tensors in flat $3$-space. In a more general spatial slice,
only one of these potentials is found, the same potential given in
\cite{BakerPuzio} and \cite{Dain}, with the remaining equations reduced to a
partial differential equation, depending on boundary conditions for a solution.
As an exercise, we also derive the potentials which give the Bowen-York
curvature tensor in flat space.
| [
{
"created": "Thu, 6 Jun 2013 10:06:01 GMT",
"version": "v1"
}
] | 2016-03-21 | [
[
"Conboye",
"Rory",
""
],
[
"Murchadha",
"Niall Ó",
""
]
] | In the initial conditions of the $3 + 1$ formalism for numerical relativity, the transverse and trace-free (TT) part of the extrinsic curvature plays a key role. We know that TT tensors possess two degrees of freedom per space point. However, finding an expression for a TT tensor depending on only two scalar functions is a non-trivial task. Assuming either axial or translational symmetry, expressions depending on two scalar potentials alone are derived here for \emph{all} TT tensors in flat $3$-space. In a more general spatial slice, only one of these potentials is found, the same potential given in \cite{BakerPuzio} and \cite{Dain}, with the remaining equations reduced to a partial differential equation, depending on boundary conditions for a solution. As an exercise, we also derive the potentials which give the Bowen-York curvature tensor in flat space. |
0707.0053 | Mehedi Kalam Dr. | M.Kalam, F.Rahaman and S.Mondal | Particle Motion Around Tachyon Monopole | 14 pages, 7 figures | Gen.Rel.Grav.40:1849-1861,2008 | 10.1007/s10714-008-0605-9 | null | gr-qc | null | Recently, Li and Liu have studied global monoole of tachyon in a four
dimensional static space-time. We analyze the motion of massless and massive
particles around tachyon monopole. Interestingly, for the bending of light rays
due to tachyon monopole instead of getting angle of deficit we find angle of
surplus. Also we find that the tachyon monopole exerts an attractive
gravitational force towards matter.
| [
{
"created": "Sat, 30 Jun 2007 10:26:07 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Kalam",
"M.",
""
],
[
"Rahaman",
"F.",
""
],
[
"Mondal",
"S.",
""
]
] | Recently, Li and Liu have studied global monoole of tachyon in a four dimensional static space-time. We analyze the motion of massless and massive particles around tachyon monopole. Interestingly, for the bending of light rays due to tachyon monopole instead of getting angle of deficit we find angle of surplus. Also we find that the tachyon monopole exerts an attractive gravitational force towards matter. |
gr-qc/0102087 | Victor P. Ruban | V.P. Ruban and D.I. Podolsky | Hydrodynamics of an ultra-relativistic fluid in the flat anisotropic
cosmological model | 4 pages, 1 eps figure, revtex | Phys.Rev.D64:047503,2001 | 10.1103/PhysRevD.64.047503 | null | gr-qc | null | Motion of an ultra-relativistic perfect fluid in space-time with the Kasner
metrics is investigated by the Hamiltonian method. It is found that in the
limit of small times a tendency takes place to formation of strong
inhomogeneities in matter distribution. In the case of slow flows the effect of
non-stationary anisotropy on dynamics of sound waves and behaviour of frozen-in
vortices is considered. It is shown that hydrodynamics of slow vortices on the
static homogeneous background is equivalent to the usual Eulerian
incompressible hydrodynamics, but in the presence of an external non-stationary
strain velocity field.
| [
{
"created": "Tue, 20 Feb 2001 17:42:02 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"Ruban",
"V. P.",
""
],
[
"Podolsky",
"D. I.",
""
]
] | Motion of an ultra-relativistic perfect fluid in space-time with the Kasner metrics is investigated by the Hamiltonian method. It is found that in the limit of small times a tendency takes place to formation of strong inhomogeneities in matter distribution. In the case of slow flows the effect of non-stationary anisotropy on dynamics of sound waves and behaviour of frozen-in vortices is considered. It is shown that hydrodynamics of slow vortices on the static homogeneous background is equivalent to the usual Eulerian incompressible hydrodynamics, but in the presence of an external non-stationary strain velocity field. |
1909.13314 | Kubantai Ernazarov | K. K. Ernazarov | Stable exponential cosmological solutions with three factor spaces of
dimensions $m=3$, $k_1=k$ and $k_2 = k$ in the Einstein-Gauss-Bonnet model
with a $\Lambda$-term | 20 pages, LaTex, no figures, to appear in IJGMMP | null | 10.1142/S0219887819300046 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a $(4 + 2k)$ - dimensional Einstein-Gauss-Bonnet model with the
cosmological $\Lambda$-term.
Exact stable solutions with three constant Hubble-like parameters in this
model are obtained. In this case, the multidimensional cosmological model deals
with three factor spaces: the external 3-dimensional "our" world and internal
subspaces with dimensions $k_1 = k$ and $k_2=k$.
| [
{
"created": "Sun, 29 Sep 2019 16:42:33 GMT",
"version": "v1"
}
] | 2020-01-29 | [
[
"Ernazarov",
"K. K.",
""
]
] | We consider a $(4 + 2k)$ - dimensional Einstein-Gauss-Bonnet model with the cosmological $\Lambda$-term. Exact stable solutions with three constant Hubble-like parameters in this model are obtained. In this case, the multidimensional cosmological model deals with three factor spaces: the external 3-dimensional "our" world and internal subspaces with dimensions $k_1 = k$ and $k_2=k$. |
gr-qc/0409046 | Jorge Pullin | Jorge Pullin | Matters of Gravity, the newsletter of the Topical Group in Gravitation
of the American Physical Society | Jorge Pullin is the editor of the paper. 26 pages, LaTex, one figure,
uses html.sty | null | null | MOG-24 | gr-qc | null | Contents:
Community news:
Message from the Chair, by Jim Isenberg
We hear that..., by Jorge Pullin
THE TGG WYP Speakers Program, by Richard Price
Research Briefs:
Gravity Probe B is launched, by Bill Hamilton
Questions and progress in mathematical general relativity, by Jim Isenberg
Summary of recent preliminary LIGO results, by Alan Wiseman for the LSC
100 Years ago, by Jorge Pullin
Conference reports:
Einstein 125, by Abhay Ashtekar
The 7th Eastern Gravity Meeting, by Deirdre Shoemaker
2004 Aspen GWADW, by Syd Meshkov
Fifth LISA Symposium, by Curt Cutler
GR17, by Brien Nolan
Loops and Spinfoams, by Carlo Rovelli
20th Pacific coast gravity meeting, by Michele Vallisneri
| [
{
"created": "Fri, 10 Sep 2004 16:05:38 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Pullin",
"Jorge",
""
]
] | Contents: Community news: Message from the Chair, by Jim Isenberg We hear that..., by Jorge Pullin THE TGG WYP Speakers Program, by Richard Price Research Briefs: Gravity Probe B is launched, by Bill Hamilton Questions and progress in mathematical general relativity, by Jim Isenberg Summary of recent preliminary LIGO results, by Alan Wiseman for the LSC 100 Years ago, by Jorge Pullin Conference reports: Einstein 125, by Abhay Ashtekar The 7th Eastern Gravity Meeting, by Deirdre Shoemaker 2004 Aspen GWADW, by Syd Meshkov Fifth LISA Symposium, by Curt Cutler GR17, by Brien Nolan Loops and Spinfoams, by Carlo Rovelli 20th Pacific coast gravity meeting, by Michele Vallisneri |
gr-qc/0509016 | Soon-Tae Hong | Soon-Tae Hong | Thermodynamics of (1+1) dilatonic black holes in global flat embedding
scheme | 5 pages | Phys.Lett. B623 (2005) 135-140 | 10.1016/j.physletb.2005.07.045 | null | gr-qc hep-th | null | We study thermodynamics of (1+1) dimensional dilatonic black holes in global
embedding Minkowski space scheme. Exploiting geometrical entropy correction we
construct consistent entropy for the charged dilatonic black hole. Moreover,
(1+1) dilatonic black holes with higher order terms are shown to possess (3+2)
global flat embedding structures regardless of the details of the lapse
function, and to yield a generic entropy.
| [
{
"created": "Mon, 5 Sep 2005 08:07:17 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Hong",
"Soon-Tae",
""
]
] | We study thermodynamics of (1+1) dimensional dilatonic black holes in global embedding Minkowski space scheme. Exploiting geometrical entropy correction we construct consistent entropy for the charged dilatonic black hole. Moreover, (1+1) dilatonic black holes with higher order terms are shown to possess (3+2) global flat embedding structures regardless of the details of the lapse function, and to yield a generic entropy. |
gr-qc/9808055 | Richard Gass | Richard G. Gass, F. Paul Esposito, L.C.R. Wijewardhana and Louis
Witten | Detecting Event Horizons and Stationary Surfaces | 23 pages, 13 figures | null | null | null | gr-qc | null | We have investigated the behavior of three curvature invariants for
Schwarzschild, Reissner-Nordstr{\o}m, Kerr, and Kerr-Newman black holes. We
have also studied these invariants for a Schwarzschild-de Sitter space-time,
the $\gamma$ metric, and for a 2+1 charged dimensional black hole. The
invariants are
$I_{1}=R_{\alpha\beta\mu\nu;\lambda}R^{\alpha\beta\mu\nu;\lambda}$,
$I_{2}=R_{\mu\nu;\lambda} R^{\mu\nu;\lambda}$, and
$I_{3}=C_{\alpha\beta\mu\nu;\lambda}C^{\alpha\beta\mu\nu;\lambda}$. For all but
the Kerr-Newman case these invariants serve as either horizon or stationary
surface detectors. The Kerr-Newman case is more complicated. We show that
$I_{1}$ vanishs on the horizon in any space-time with a Schwarzschild like
metric.
| [
{
"created": "Thu, 20 Aug 1998 13:07:26 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Gass",
"Richard G.",
""
],
[
"Esposito",
"F. Paul",
""
],
[
"Wijewardhana",
"L. C. R.",
""
],
[
"Witten",
"Louis",
""
]
] | We have investigated the behavior of three curvature invariants for Schwarzschild, Reissner-Nordstr{\o}m, Kerr, and Kerr-Newman black holes. We have also studied these invariants for a Schwarzschild-de Sitter space-time, the $\gamma$ metric, and for a 2+1 charged dimensional black hole. The invariants are $I_{1}=R_{\alpha\beta\mu\nu;\lambda}R^{\alpha\beta\mu\nu;\lambda}$, $I_{2}=R_{\mu\nu;\lambda} R^{\mu\nu;\lambda}$, and $I_{3}=C_{\alpha\beta\mu\nu;\lambda}C^{\alpha\beta\mu\nu;\lambda}$. For all but the Kerr-Newman case these invariants serve as either horizon or stationary surface detectors. The Kerr-Newman case is more complicated. We show that $I_{1}$ vanishs on the horizon in any space-time with a Schwarzschild like metric. |
2101.08791 | Marvin L\"uben | Angelo Caravano, Marvin L\"uben, Jochen Weller | Combining cosmological and local bounds on bimetric theory | null | null | 10.1088/1475-7516/2021/09/035 | MPP-2021-6 | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by/4.0/ | Ghost-free bimetric theory describes two nonlinearly interacting spin-2
fields, one massive and one massless, thus extending general relativity. We
confront bimetric theory with observations of Supernovae type 1a, Baryon
Acoustic Oscillations and the Cosmic Microwave Background in a statistical
analysis, utilising the recently proposed physical parametrisation. This
directly constrains the physical parameters of the theory, such as the mass of
the spin-2 field and its coupling to matter. We find that all models under
consideration are in agreement with the data. Next, we compare these results to
bounds from local tests of gravity. Our analysis reveals that all two- and
three-parameter models are observationally consistent with both cosmological
and local tests of gravity. The minimal bimetric model (only $\beta_1$) is
ruled out by our combined analysis.
| [
{
"created": "Thu, 21 Jan 2021 19:00:01 GMT",
"version": "v1"
}
] | 2021-10-04 | [
[
"Caravano",
"Angelo",
""
],
[
"Lüben",
"Marvin",
""
],
[
"Weller",
"Jochen",
""
]
] | Ghost-free bimetric theory describes two nonlinearly interacting spin-2 fields, one massive and one massless, thus extending general relativity. We confront bimetric theory with observations of Supernovae type 1a, Baryon Acoustic Oscillations and the Cosmic Microwave Background in a statistical analysis, utilising the recently proposed physical parametrisation. This directly constrains the physical parameters of the theory, such as the mass of the spin-2 field and its coupling to matter. We find that all models under consideration are in agreement with the data. Next, we compare these results to bounds from local tests of gravity. Our analysis reveals that all two- and three-parameter models are observationally consistent with both cosmological and local tests of gravity. The minimal bimetric model (only $\beta_1$) is ruled out by our combined analysis. |
gr-qc/9508066 | Eanna Flanagan | Omos Ori and Eanna Flanagan | How generic are null spacetime singularities? | 5 pages, 1 uuencoded figure, uses revtex macros Revised 25/2/95 to
correct the definition of weak singularities | Phys.Rev.D53:1754-1758,1996 | 10.1103/PhysRevD.53.1754 | null | gr-qc | null | The spacetime singularities inside realistic black holes are sometimes
thought to be spacelike and strong, since there is a generic class of solutions
(BKL) to Einsteins equations with these properties. We show that null, weak
singularities are also generic, in the following sense: there is a class of
vacuum solutions containing null, weak singularities, depending on 8 arbitrary
(up to some inequalities) analytic initial functions of 3 spatial coordinates.
Since 8 arbitrary functions are needed (in the gauge used here) to span the
generic solution, this class can be regarded as generic.
| [
{
"created": "Thu, 31 Aug 1995 22:09:51 GMT",
"version": "v1"
},
{
"created": "Sun, 25 Feb 1996 21:47:31 GMT",
"version": "v2"
}
] | 2009-12-30 | [
[
"Ori",
"Omos",
""
],
[
"Flanagan",
"Eanna",
""
]
] | The spacetime singularities inside realistic black holes are sometimes thought to be spacelike and strong, since there is a generic class of solutions (BKL) to Einsteins equations with these properties. We show that null, weak singularities are also generic, in the following sense: there is a class of vacuum solutions containing null, weak singularities, depending on 8 arbitrary (up to some inequalities) analytic initial functions of 3 spatial coordinates. Since 8 arbitrary functions are needed (in the gauge used here) to span the generic solution, this class can be regarded as generic. |
2111.06897 | Sumanta Chakraborty | Justin C. Feng and Sumanta Chakraborty | Weiss variation for general boundaries | v2, Published in the GERG memorial volume for Prof. T. Padmanabhan,
25 pages, 1 figure | Gen. Relt. Grav. 54, 67 (2022) | 10.1007/s10714-022-02953-0 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Weiss variation of the Einstein-Hilbert action with an appropriate
boundary term has been studied for general boundary surfaces; the boundary
surfaces can be spacelike, timelike, or null. To achieve this we introduce an
auxiliary reference connection and find that the resulting Weiss variation
yields the Einstein equations as expected, with additional boundary
contributions. Among these boundary contributions, we obtain the dynamical
variable and the associated conjugate momentum, irrespective of the spacelike,
timelike or, null nature of the boundary surface. We also arrive at the
generally non-vanishing covariant generalization of the Einstein
energy-momentum pseudotensor. We study this tensor in the Schwarzschild
geometry and find that the pseudotensorial ambiguities translate into
ambiguities in the choice of coordinates on the reference geometry. Moreover,
we show that from the Weiss variation, one can formally derive a gravitational
Schr{\"o}dinger equation, which may, despite ambiguities in the definition of
the Hamiltonian, be useful as a tool for studying the problem of time in
quantum general relativity. Implications have been discussed.
| [
{
"created": "Fri, 12 Nov 2021 19:00:00 GMT",
"version": "v1"
},
{
"created": "Tue, 19 Jul 2022 01:56:08 GMT",
"version": "v2"
}
] | 2022-07-20 | [
[
"Feng",
"Justin C.",
""
],
[
"Chakraborty",
"Sumanta",
""
]
] | The Weiss variation of the Einstein-Hilbert action with an appropriate boundary term has been studied for general boundary surfaces; the boundary surfaces can be spacelike, timelike, or null. To achieve this we introduce an auxiliary reference connection and find that the resulting Weiss variation yields the Einstein equations as expected, with additional boundary contributions. Among these boundary contributions, we obtain the dynamical variable and the associated conjugate momentum, irrespective of the spacelike, timelike or, null nature of the boundary surface. We also arrive at the generally non-vanishing covariant generalization of the Einstein energy-momentum pseudotensor. We study this tensor in the Schwarzschild geometry and find that the pseudotensorial ambiguities translate into ambiguities in the choice of coordinates on the reference geometry. Moreover, we show that from the Weiss variation, one can formally derive a gravitational Schr{\"o}dinger equation, which may, despite ambiguities in the definition of the Hamiltonian, be useful as a tool for studying the problem of time in quantum general relativity. Implications have been discussed. |
1104.1122 | Riccardo Sturani | S. Foffa and R. Sturani | Effective field theory calculation of conservative binary dynamics at
third post-Newtonian order | 24 pages, 6 figures. Typos corrected and references added in v2.
Typos corrected in v3 | Phys.Rev.D84:044031,2011 | 10.1103/PhysRevD.84.044031 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We reproduce the two-body gravitational conservative dynamics at third
post-Newtonian order for spin-less sources by using the effective field theory
methods for the gravitationally bound two-body system, proposed by Goldberger
and Rothstein. This result has been obtained by automatizing the computation of
Feynman amplitudes within a Mathematica algorithm, paving the way for
higher-order computations not yet performed by traditional methods.
| [
{
"created": "Wed, 6 Apr 2011 14:54:41 GMT",
"version": "v1"
},
{
"created": "Wed, 22 Jun 2011 14:33:59 GMT",
"version": "v2"
},
{
"created": "Sat, 19 Nov 2011 12:17:26 GMT",
"version": "v3"
}
] | 2015-03-19 | [
[
"Foffa",
"S.",
""
],
[
"Sturani",
"R.",
""
]
] | We reproduce the two-body gravitational conservative dynamics at third post-Newtonian order for spin-less sources by using the effective field theory methods for the gravitationally bound two-body system, proposed by Goldberger and Rothstein. This result has been obtained by automatizing the computation of Feynman amplitudes within a Mathematica algorithm, paving the way for higher-order computations not yet performed by traditional methods. |
gr-qc/9605069 | Ichiro Oda | Akio Hosoya and Ichiro Oda | Black Hole Singularity and Generalized Quantum Affine Parameter | 17 pages, phyzzx | null | null | TIT/HEP-334/COSMO-73, EDO-EP-5 | gr-qc | null | We study a behavior of quantum generalized affine parameter (QGAP), which has
been recently proposed by one of the present authors, near the singularity and
the event horizon in three and four spacetime dimensions in terms of a
minisuperspace model of quantum gravity. It is shown that the QGAP is infinite
to the singularity while it remains finite to the event horizon. This fact
indicates a possible interpretation that the singularity is wiped out in
quantum gravity in this particular model of black hole.
| [
{
"created": "Fri, 31 May 1996 06:11:32 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Hosoya",
"Akio",
""
],
[
"Oda",
"Ichiro",
""
]
] | We study a behavior of quantum generalized affine parameter (QGAP), which has been recently proposed by one of the present authors, near the singularity and the event horizon in three and four spacetime dimensions in terms of a minisuperspace model of quantum gravity. It is shown that the QGAP is infinite to the singularity while it remains finite to the event horizon. This fact indicates a possible interpretation that the singularity is wiped out in quantum gravity in this particular model of black hole. |
2306.02504 | Rodrigo Dal Bosco Fontana | R. D. B Fontana | Scalar field instabilities in charged BTZ black holes | 3 figures, 5 panels, 15 pages | null | 10.1103/PhysRevD.109.044039 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the charged scalar field propagating in a (2+1) charged BTZ
black hole. The conditions for stability are studied unveiling, for each black
hole geometry, the existence of a critical scalar charge as of the evolution is
unstable. The existence of growing profiles is substantiated by the deep in the
effective potential that intensifies as the scalar charge increases. The
phenomenum happens in every black hole geometry even for small geometry charge.
In the small scalar charge regime, the field evolution is stable and in such we
calculate the quasinormal modes.
| [
{
"created": "Sun, 4 Jun 2023 23:34:00 GMT",
"version": "v1"
},
{
"created": "Mon, 26 Feb 2024 16:00:23 GMT",
"version": "v2"
}
] | 2024-02-27 | [
[
"Fontana",
"R. D. B",
""
]
] | We investigate the charged scalar field propagating in a (2+1) charged BTZ black hole. The conditions for stability are studied unveiling, for each black hole geometry, the existence of a critical scalar charge as of the evolution is unstable. The existence of growing profiles is substantiated by the deep in the effective potential that intensifies as the scalar charge increases. The phenomenum happens in every black hole geometry even for small geometry charge. In the small scalar charge regime, the field evolution is stable and in such we calculate the quasinormal modes. |
2207.07733 | Makana Silva | Makana Silva and Christopher Hirata | Dynamical perturbations around an extreme mass ratio inspiral near
resonance | 19 pages, 5 figures, 1 table, to be submitted to PRD | null | 10.1103/PhysRevD.106.084058 | null | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | Extreme mass ratio inspirals (EMRIs) -- systems with a compact object
orbiting a much more massive (e.g., galactic center) black hole -- are of
interest both as a new probe of the environments of galactic nuclei, and their
waveforms are a precision test of the Kerr metric. This work focuses on the
effects of an external perturbation due to a third body around an EMRI system.
This perturbation will affect the orbit most significantly when the inner body
crosses a resonance with the outer body, and result in a change of the
conserved quantities (energy, angular momentum, and Carter constant) or
equivalently of the actions, which results in a subsequent phase shift of the
waveform that builds up over time. We present a general method for calculating
the changes in action during a resonance crossing, valid for generic orbits in
the Kerr spacetime. We show that these changes are related to the gravitational
waveforms emitted by the two bodies (quantified by the amplitudes of the Weyl
scalar $\psi_4$ at the horizon and at $\infty$) at the frequency corresponding
to the resonance. This allows us to compute changes in the action variables for
each body, without directly computing the explicit metric perturbations, and
therefore we can carry out the computation by calling an existing black hole
perturbation theory code. We show that our calculation can probe resonant
interactions in both the static and dynamical limit. We plan to use this
technique for future investigations of third-body effects in EMRIs and their
potential impact on waveforms for LISA.
| [
{
"created": "Fri, 15 Jul 2022 20:09:32 GMT",
"version": "v1"
}
] | 2022-11-09 | [
[
"Silva",
"Makana",
""
],
[
"Hirata",
"Christopher",
""
]
] | Extreme mass ratio inspirals (EMRIs) -- systems with a compact object orbiting a much more massive (e.g., galactic center) black hole -- are of interest both as a new probe of the environments of galactic nuclei, and their waveforms are a precision test of the Kerr metric. This work focuses on the effects of an external perturbation due to a third body around an EMRI system. This perturbation will affect the orbit most significantly when the inner body crosses a resonance with the outer body, and result in a change of the conserved quantities (energy, angular momentum, and Carter constant) or equivalently of the actions, which results in a subsequent phase shift of the waveform that builds up over time. We present a general method for calculating the changes in action during a resonance crossing, valid for generic orbits in the Kerr spacetime. We show that these changes are related to the gravitational waveforms emitted by the two bodies (quantified by the amplitudes of the Weyl scalar $\psi_4$ at the horizon and at $\infty$) at the frequency corresponding to the resonance. This allows us to compute changes in the action variables for each body, without directly computing the explicit metric perturbations, and therefore we can carry out the computation by calling an existing black hole perturbation theory code. We show that our calculation can probe resonant interactions in both the static and dynamical limit. We plan to use this technique for future investigations of third-body effects in EMRIs and their potential impact on waveforms for LISA. |
1602.00581 | Yu Zhang | En-Kun Li, Yu Zhang, Jin-Ling Geng, Peng-Fei Duan | Generalized holographic Ricci dark energy and generalized second law of
thermodynamics in Bianchi Type I universe | 11 pages, 4 figures | Gen. Relativ. Gravit. (2015) 47:136 | 10.1007/s10714-015-1983-4 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Generalized second law of thermodynamics in the Bianchi type I universe with
the generalized holographic Ricci dark energy model is studied in this paper.
The behavior of dark energy's equation of state parameter indicates that it is
matter-like in the early time of the universe but phantom-like in the future.
By analysing the evolution of the deviations of state parameter and the total
pressure of the universe, we find that for an anisotropic Bianchi type I
universe, it transits from a high anisotropy stage to a more homogeneous stage
in the near past. Using the normal entropy given by Gibbs' law of
thermodynamics, it is proved that the generalized second law of thermodynamics
does not always satisfied throughout the history of the universe when we assume
the universe is enclosed by the generalized Ricci scalar radius $R_{gr}$. It
becomes invalid in the near past to the future, and the formation of the
galaxies will be helpful in explaining such phenomenon, for that the galaxies's
formation is an entropy increase process. The negative change rates of the
horizon entropy and internal entropy occur in different period indicates that
the influences of galaxies formation is wiped from internal to the universe's
horizon.
| [
{
"created": "Fri, 29 Jan 2016 17:16:35 GMT",
"version": "v1"
}
] | 2016-02-02 | [
[
"Li",
"En-Kun",
""
],
[
"Zhang",
"Yu",
""
],
[
"Geng",
"Jin-Ling",
""
],
[
"Duan",
"Peng-Fei",
""
]
] | Generalized second law of thermodynamics in the Bianchi type I universe with the generalized holographic Ricci dark energy model is studied in this paper. The behavior of dark energy's equation of state parameter indicates that it is matter-like in the early time of the universe but phantom-like in the future. By analysing the evolution of the deviations of state parameter and the total pressure of the universe, we find that for an anisotropic Bianchi type I universe, it transits from a high anisotropy stage to a more homogeneous stage in the near past. Using the normal entropy given by Gibbs' law of thermodynamics, it is proved that the generalized second law of thermodynamics does not always satisfied throughout the history of the universe when we assume the universe is enclosed by the generalized Ricci scalar radius $R_{gr}$. It becomes invalid in the near past to the future, and the formation of the galaxies will be helpful in explaining such phenomenon, for that the galaxies's formation is an entropy increase process. The negative change rates of the horizon entropy and internal entropy occur in different period indicates that the influences of galaxies formation is wiped from internal to the universe's horizon. |
gr-qc/0107057 | Abel Camacho Quintana | Abel Camacho (Dept. of Physics, Instituto Nacional de Investigaciones
Nucleares) | Non--Newtonian gravity and coherence properties of light | 10 pages, accepted in Physics Letters A | Phys.Lett. A287 (2001) 339-343 | 10.1016/S0375-9601(01)00496-0 | null | gr-qc quant-ph | null | In this work the possibility of detecting a non--Newtonian contribution to
the gravitational potential by means of its effects upon the first and
second--order coherence properties of light is analyzed. It will be proved
that, in principle, the effects of a fifth force upon the correlation functions
of electromagnetic radiation could be used to detect the existence of new
forces. Some constraints upon the experimental parameters will also be deduced.
| [
{
"created": "Mon, 16 Jul 2001 14:11:44 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Camacho",
"Abel",
"",
"Dept. of Physics, Instituto Nacional de Investigaciones\n Nucleares"
]
] | In this work the possibility of detecting a non--Newtonian contribution to the gravitational potential by means of its effects upon the first and second--order coherence properties of light is analyzed. It will be proved that, in principle, the effects of a fifth force upon the correlation functions of electromagnetic radiation could be used to detect the existence of new forces. Some constraints upon the experimental parameters will also be deduced. |
2004.04178 | Dawood Kothawala Dr. | Dawood Kothawala | Varying without varying: Reparameterisations, Diffeomorphisms, General
Covariance, Lie derivatives, and all that | v2: 32 pages, 4 figures, certain discussions expanded; v1: 26 pages,
4 figures | Eur. J. Phys. 42, 055601 (2021) | 10.1088/1361-6404/ac0105 | null | gr-qc physics.class-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The standard way of deriving Euler-Lagrange (EL) equations given a point
particle action is to vary the trajectory and set the first variation of the
action to zero. However, if the action is (i) reparameterisation invariant, and
(ii) generally covariant, I show that one may derive the EL equations by
suitably "nullifying" the variation through a judicious coordinate
transformation. The net result of this is that the curve remains fixed, while
all other geometrical objects in the action undergo a change, given precisely
by the Lie derivatives along the variation vector field. This, then, is the
most direct and transparent way to elucidate the connection between general
covariance, diffeomorphism invariance, and Lie derivatives, without referring
to covariant derivative.
I highlight the geometric underpinnings and generality of above ideas by
applying them to simplest of field theories, keeping the discussion at a level
easily accessible to advanced undergraduates. As non-trivial applications of
these ideas, I (i) derive the Geodesic Deviation Equation using first order
diffeomorphisms, and (ii) demonstrate how they can highlight the connection
between canonical and metric stress-energy tensors in field theories.
| [
{
"created": "Wed, 8 Apr 2020 18:00:12 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Jun 2021 16:14:25 GMT",
"version": "v2"
}
] | 2021-06-15 | [
[
"Kothawala",
"Dawood",
""
]
] | The standard way of deriving Euler-Lagrange (EL) equations given a point particle action is to vary the trajectory and set the first variation of the action to zero. However, if the action is (i) reparameterisation invariant, and (ii) generally covariant, I show that one may derive the EL equations by suitably "nullifying" the variation through a judicious coordinate transformation. The net result of this is that the curve remains fixed, while all other geometrical objects in the action undergo a change, given precisely by the Lie derivatives along the variation vector field. This, then, is the most direct and transparent way to elucidate the connection between general covariance, diffeomorphism invariance, and Lie derivatives, without referring to covariant derivative. I highlight the geometric underpinnings and generality of above ideas by applying them to simplest of field theories, keeping the discussion at a level easily accessible to advanced undergraduates. As non-trivial applications of these ideas, I (i) derive the Geodesic Deviation Equation using first order diffeomorphisms, and (ii) demonstrate how they can highlight the connection between canonical and metric stress-energy tensors in field theories. |
gr-qc/0301059 | Brian Edgar | Raffaele Rani, S. Brian Edgar and Alan Barnes | Killing Tensors and Conformal Killing Tensors from Conformal Killing
Vectors | 18 pages References added. Comments and reference to 2-dim case.
Typos corrected | Class.Quant.Grav. 20 (2003) 1929-1942 | 10.1088/0264-9381/20/11/301 | null | gr-qc | null | Koutras has proposed some methods to construct reducible proper conformal
Killing tensors and Killing tensors (which are, in general, irreducible) when a
pair of orthogonal conformal Killing vectors exist in a given space. We give
the completely general result demonstrating that this severe restriction of
orthogonality is unnecessary. In addition we correct and extend some results
concerning Killing tensors constructed from a single conformal Killing vector.
A number of examples demonstrate how it is possible to construct a much larger
class of reducible proper conformal Killing tensors and Killing tensors than
permitted by the Koutras algorithms. In particular, by showing that all
conformal Killing tensors are reducible in conformally flat spaces, we have a
method of constructing all conformal Killing tensors (including all the Killing
tensors which will in general be irreducible) of conformally flat spaces using
their conformal Killing vectors.
| [
{
"created": "Thu, 16 Jan 2003 16:11:29 GMT",
"version": "v1"
},
{
"created": "Tue, 21 Jan 2003 20:24:47 GMT",
"version": "v2"
},
{
"created": "Wed, 12 Mar 2003 16:41:38 GMT",
"version": "v3"
}
] | 2009-11-10 | [
[
"Rani",
"Raffaele",
""
],
[
"Edgar",
"S. Brian",
""
],
[
"Barnes",
"Alan",
""
]
] | Koutras has proposed some methods to construct reducible proper conformal Killing tensors and Killing tensors (which are, in general, irreducible) when a pair of orthogonal conformal Killing vectors exist in a given space. We give the completely general result demonstrating that this severe restriction of orthogonality is unnecessary. In addition we correct and extend some results concerning Killing tensors constructed from a single conformal Killing vector. A number of examples demonstrate how it is possible to construct a much larger class of reducible proper conformal Killing tensors and Killing tensors than permitted by the Koutras algorithms. In particular, by showing that all conformal Killing tensors are reducible in conformally flat spaces, we have a method of constructing all conformal Killing tensors (including all the Killing tensors which will in general be irreducible) of conformally flat spaces using their conformal Killing vectors. |
gr-qc/9809032 | John W. Barrett | John W. Barrett, Ruth M. Williams | The asymptotics of an amplitude for the 4-simplex | 5 pages amstex, typos corrected | Adv.Theor.Math.Phys. 3 (1999) 209-215 | null | null | gr-qc | null | An expression for the oscillatory part of an asymptotic formula for the
relativistic spin network amplitude for a 4-simplex is given. The amplitude
depends on specified areas for each two-dimensional face in the 4-simplex. The
asymptotic formula has a contribution from each flat Euclidean metric on the
4-simplex which agrees with the given areas. The oscillatory part of each
contribution is determined by the Regge calculus Einstein action for that
geometry.
| [
{
"created": "Tue, 8 Sep 1998 09:49:32 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Feb 1999 14:05:32 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Barrett",
"John W.",
""
],
[
"Williams",
"Ruth M.",
""
]
] | An expression for the oscillatory part of an asymptotic formula for the relativistic spin network amplitude for a 4-simplex is given. The amplitude depends on specified areas for each two-dimensional face in the 4-simplex. The asymptotic formula has a contribution from each flat Euclidean metric on the 4-simplex which agrees with the given areas. The oscillatory part of each contribution is determined by the Regge calculus Einstein action for that geometry. |
2403.10605 | Dimitrios Giataganas | D. Giataganas, A. Kehagias, A. Riotto | Quasinormal Modes and Universality of the Penrose Limit of Black Hole
Photon Rings | 33 pages | null | null | null | gr-qc astro-ph.CO astro-ph.HE hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the physics of photon rings in a wide range of axisymmetric black
holes admitting a separable Hamilton-Jacobi equation for the geodesics.
Utilizing the Killing-Yano tensor, we derive the Penrose limit of the black
holes, which describes the physics near the photon ring. The obtained plane
wave geometry is directly linked to the frequency matrix of the massless wave
equation, as well as the instabilities and Lyapunov exponents of the null
geodesics. Consequently, the Lyapunov exponents and frequencies of the photon
geodesics, along with the quasinormal modes, can be all extracted from a
Hamiltonian in the Penrose limit plane wave metric. Additionally, we explore
potential bounds on the Lyapunov exponent, the orbital and precession
frequencies, in connection with the corresponding inverted harmonic oscillators
and we discuss the possibility of photon rings serving as holographic horizons
in a holographic duality framework for astrophysical black holes. Our formalism
is applicable to spacetimes encompassing various types of black holes,
including stationary ones like Kerr, Kerr-Newman, as well as static black holes
such as Schwarzschild, Reissner-Nordstr\"om, among others.
| [
{
"created": "Fri, 15 Mar 2024 18:00:39 GMT",
"version": "v1"
}
] | 2024-03-20 | [
[
"Giataganas",
"D.",
""
],
[
"Kehagias",
"A.",
""
],
[
"Riotto",
"A.",
""
]
] | We study the physics of photon rings in a wide range of axisymmetric black holes admitting a separable Hamilton-Jacobi equation for the geodesics. Utilizing the Killing-Yano tensor, we derive the Penrose limit of the black holes, which describes the physics near the photon ring. The obtained plane wave geometry is directly linked to the frequency matrix of the massless wave equation, as well as the instabilities and Lyapunov exponents of the null geodesics. Consequently, the Lyapunov exponents and frequencies of the photon geodesics, along with the quasinormal modes, can be all extracted from a Hamiltonian in the Penrose limit plane wave metric. Additionally, we explore potential bounds on the Lyapunov exponent, the orbital and precession frequencies, in connection with the corresponding inverted harmonic oscillators and we discuss the possibility of photon rings serving as holographic horizons in a holographic duality framework for astrophysical black holes. Our formalism is applicable to spacetimes encompassing various types of black holes, including stationary ones like Kerr, Kerr-Newman, as well as static black holes such as Schwarzschild, Reissner-Nordstr\"om, among others. |
1605.03404 | Mahouton J. Stephane Houndjo Dr | R. D. Boko, M. J. S. Houndjo, J. Tossa | Stability and Space Phase Analysis in f(R) theory with Generalized
Exponential model | 16 pages and 6 figures, version accepted for publication in IJMPD | International Journal of Modern Physics D Vol. 25, No. 10, 1650098
(2016) | 10.1142/S021827181650098X | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We have studied in this paper, the stability of dynamical system in $f(R)$
gravity. We have considered the $f(R)$ $\gamma$-gravity and explored its
dynamical analysis. We found six critical points among which only one describes
an universe fulled of both matter and dominated dark energy. It's shown that
these critical points presents specific phase spaces described by the
corresponding fluids. Furthermore, we've investigated the stability conditions
of these critical points and find that theses conditions are dependent of the
model parameters. We also study the stability of a new power-law $f_\ast(R)$
model with de Sitter and power law solutions.
| [
{
"created": "Wed, 4 May 2016 23:50:15 GMT",
"version": "v1"
}
] | 2016-11-29 | [
[
"Boko",
"R. D.",
""
],
[
"Houndjo",
"M. J. S.",
""
],
[
"Tossa",
"J.",
""
]
] | We have studied in this paper, the stability of dynamical system in $f(R)$ gravity. We have considered the $f(R)$ $\gamma$-gravity and explored its dynamical analysis. We found six critical points among which only one describes an universe fulled of both matter and dominated dark energy. It's shown that these critical points presents specific phase spaces described by the corresponding fluids. Furthermore, we've investigated the stability conditions of these critical points and find that theses conditions are dependent of the model parameters. We also study the stability of a new power-law $f_\ast(R)$ model with de Sitter and power law solutions. |
2407.04175 | Tetsuya Shiromizu | Keisuke Izumi, Tetsuya Shiromizu, Daisuke Yoshida, Yoshimune Tomikawa
and Hirotaka Yoshino | Loosely trapped surface for slowly rotating black hole | 7 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct the marginal loosely trapped surface (marginal LTS) for the Kerr
spacetime with a small Kerr parameter perturbatively, where the LTS condition
is saturated. An LTS is a surface that specifies the strong gravity region,
which is a generalization of the photon sphere in the Schwarzschild spacetime.
It turns out that there are an infinite number of marginal LTSs. At the leading
order of the small Kerr parameter, all of the marginal LTSs have the same area.
However, one can see that the maximal marginal LTS among them is uniquely
determined at the higher order.
| [
{
"created": "Thu, 4 Jul 2024 22:22:28 GMT",
"version": "v1"
},
{
"created": "Tue, 16 Jul 2024 05:41:26 GMT",
"version": "v2"
}
] | 2024-07-17 | [
[
"Izumi",
"Keisuke",
""
],
[
"Shiromizu",
"Tetsuya",
""
],
[
"Yoshida",
"Daisuke",
""
],
[
"Tomikawa",
"Yoshimune",
""
],
[
"Yoshino",
"Hirotaka",
""
]
] | We construct the marginal loosely trapped surface (marginal LTS) for the Kerr spacetime with a small Kerr parameter perturbatively, where the LTS condition is saturated. An LTS is a surface that specifies the strong gravity region, which is a generalization of the photon sphere in the Schwarzschild spacetime. It turns out that there are an infinite number of marginal LTSs. At the leading order of the small Kerr parameter, all of the marginal LTSs have the same area. However, one can see that the maximal marginal LTS among them is uniquely determined at the higher order. |
0712.3716 | Orchidea Maria Lecian | S. Casanova, O. M. Lecian, G. Montani, R. Ruffini, R. Zalaletdinov | Extended Schouten classification for non-Riemannian geometries | 7 pages, to appear on Mod. Phys. Lett. A | Mod.Phys.Lett.A23:17-23,2008 | 10.1142/S0217732308026157 | null | gr-qc | null | A generalized connection, including Christoffel coefficients, torsion,
non-metricity tensor and metric-asymmetricity object, is analyzed according to
the Schouten classification. The inverse structure matrix is found in the
linearized regime, autoparallel trajectories are defined and the contribution
of the components of the connection are clarified at first-order approximation.
| [
{
"created": "Fri, 21 Dec 2007 15:26:53 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Casanova",
"S.",
""
],
[
"Lecian",
"O. M.",
""
],
[
"Montani",
"G.",
""
],
[
"Ruffini",
"R.",
""
],
[
"Zalaletdinov",
"R.",
""
]
] | A generalized connection, including Christoffel coefficients, torsion, non-metricity tensor and metric-asymmetricity object, is analyzed according to the Schouten classification. The inverse structure matrix is found in the linearized regime, autoparallel trajectories are defined and the contribution of the components of the connection are clarified at first-order approximation. |
gr-qc/9606009 | Tigran Aivazian | Tigran Aivazian | On the link between Shrodinger and Vlasov Equations | 2 pages, LaTex, no figures | null | null | null | gr-qc | null | It is shown that well-known Vlasov equation can be derived by adding "hidden"
degrees of freedom and subsequent quantization. The Shrodinger equation
obtained in this manner coincides (in x-representation) with the kinetic
equation for the original dynamical system
| [
{
"created": "Wed, 5 Jun 1996 22:42:22 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Aivazian",
"Tigran",
""
]
] | It is shown that well-known Vlasov equation can be derived by adding "hidden" degrees of freedom and subsequent quantization. The Shrodinger equation obtained in this manner coincides (in x-representation) with the kinetic equation for the original dynamical system |
1203.6526 | Norbert Bodendorfer | Norbert Bodendorfer, Alexander Stottmeister, Andreas Thurn | On a partially reduced phase space quantisation of general relativity
conformally coupled to a scalar field | 51 pages, 5 figures. v2: Gauge condition used shown to coincide with
CMC gauge. Minor clarifications and corrections | Class. Quantum Grav. 30 (2013) 115017 | 10.1088/0264-9381/30/11/115017 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The purpose of this paper is twofold: On the one hand, after a thorough
review of the matter free case, we supplement the derivations in our companion
paper on 'loop quantum gravity without the Hamiltonian constraint' with
calculational details and extend the results to standard model matter, a
cosmological constant, and non-compact spatial slices. On the other hand, we
provide a discussion on the role of observables, focussed on the situation of a
symmetry exchange, which is key to our derivation. Furthermore, we comment on
the relation of our model to reduced phase space quantisations based on
deparametrisation.
| [
{
"created": "Thu, 29 Mar 2012 14:08:13 GMT",
"version": "v1"
},
{
"created": "Sun, 3 Feb 2013 18:58:11 GMT",
"version": "v2"
}
] | 2013-05-14 | [
[
"Bodendorfer",
"Norbert",
""
],
[
"Stottmeister",
"Alexander",
""
],
[
"Thurn",
"Andreas",
""
]
] | The purpose of this paper is twofold: On the one hand, after a thorough review of the matter free case, we supplement the derivations in our companion paper on 'loop quantum gravity without the Hamiltonian constraint' with calculational details and extend the results to standard model matter, a cosmological constant, and non-compact spatial slices. On the other hand, we provide a discussion on the role of observables, focussed on the situation of a symmetry exchange, which is key to our derivation. Furthermore, we comment on the relation of our model to reduced phase space quantisations based on deparametrisation. |
2004.14156 | Alexander Shatskiy Doctor | Shatskiy Alexander | Analysis of the Topology of the Kerr Metric | 20 pages, 3 figures | Journal of Experimental and Theoretical Physics, 2020, Vol. 130, N
3, p. 409 | null | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The equations of motion of a test particle are integrated for the field of a
rotating Kerr black hole (BH). Due to the lack of analytical transformations
for the Carter-Penrose diagrams (CPDs) for the Kerr metric, the topology of the
Kerr BH is studied by analytical investigation of the equations of motion.
Transformations for the CPDs for the Reisner-Nordstr\"om metric are analyzed.
The problem of boundary conditions for the Reisner-Nordstr\"om topology is
analyzed. A solution to this problem of boundary conditions is proposed. It is
proved that, in the Reisner-Nordstr\"om topology, only one way to go to another
universe is possible. For the Kerr topology, the possibility of the existence
of an alternative transition to another universe that does not coincide with
the universe for the ordinary transition is found. This alternative transition
is performed through a surface with a zero radial coordinate (zero radius).
Initial conditions for the falling particle are found that correspond to an
alternative transition to another universe. The tidal forces acting on a
falling body in the Kerr metric are estimated, and the possibility of the
transition of the body to other universes without being destroyed by tidal
forces is proved.
| [
{
"created": "Wed, 29 Apr 2020 12:58:50 GMT",
"version": "v1"
}
] | 2020-04-30 | [
[
"Alexander",
"Shatskiy",
""
]
] | The equations of motion of a test particle are integrated for the field of a rotating Kerr black hole (BH). Due to the lack of analytical transformations for the Carter-Penrose diagrams (CPDs) for the Kerr metric, the topology of the Kerr BH is studied by analytical investigation of the equations of motion. Transformations for the CPDs for the Reisner-Nordstr\"om metric are analyzed. The problem of boundary conditions for the Reisner-Nordstr\"om topology is analyzed. A solution to this problem of boundary conditions is proposed. It is proved that, in the Reisner-Nordstr\"om topology, only one way to go to another universe is possible. For the Kerr topology, the possibility of the existence of an alternative transition to another universe that does not coincide with the universe for the ordinary transition is found. This alternative transition is performed through a surface with a zero radial coordinate (zero radius). Initial conditions for the falling particle are found that correspond to an alternative transition to another universe. The tidal forces acting on a falling body in the Kerr metric are estimated, and the possibility of the transition of the body to other universes without being destroyed by tidal forces is proved. |
2311.17540 | Joanna Gonera | Joanna Piwnik, Joanna Gonera, Piotr Kosi\'nski | Herglotz variational principle and Fermat principle in arbitrary metric | 9 pages, no figures, small editorial changes | null | null | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Lagrangian formalism for the Lagrangians homogeneous of degree two in
velocities is considered. It is shown that the reduced dynamics obtained by
neglecting one generalized coordinate is, in general, described by the Herglotz
extension of Lagrangian formalism. This result is applied to the propagation of
light in general gravitational field leading to the extended Fermat principle.
| [
{
"created": "Wed, 29 Nov 2023 11:21:08 GMT",
"version": "v1"
},
{
"created": "Thu, 14 Dec 2023 13:33:30 GMT",
"version": "v2"
}
] | 2023-12-15 | [
[
"Piwnik",
"Joanna",
""
],
[
"Gonera",
"Joanna",
""
],
[
"Kosiński",
"Piotr",
""
]
] | Lagrangian formalism for the Lagrangians homogeneous of degree two in velocities is considered. It is shown that the reduced dynamics obtained by neglecting one generalized coordinate is, in general, described by the Herglotz extension of Lagrangian formalism. This result is applied to the propagation of light in general gravitational field leading to the extended Fermat principle. |
gr-qc/0601059 | Paul S. Wesson | Paul S. Wesson | Wave Mechanics and General Relativity: A Rapprochement | null | Gen.Rel.Grav. 38 (2006) 937-944 | 10.1007/s10714-006-0273-6 | null | gr-qc | null | Using exact solutions, we show that it is in principle possible to regard
waves and particles as representations of the same underlying geometry, thereby
resolving the problem of wave-particle duality.
| [
{
"created": "Mon, 16 Jan 2006 02:15:14 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Wesson",
"Paul S.",
""
]
] | Using exact solutions, we show that it is in principle possible to regard waves and particles as representations of the same underlying geometry, thereby resolving the problem of wave-particle duality. |
2404.14881 | Diego Rubiera-Garcia | Roberto V. Maluf, Gerardo Mora-P\'erez, Gonzalo J. Olmo, Diego
Rubiera-Garcia | Nonsingular, lump-like, scalar compact objects in $(2+1)$-dimensional
Einstein gravity | 9 pages, 3 figures | Universe 2024, 10(6), 258 | 10.3390/universe10060258 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We study the space-time geometry generated by coupling a free scalar field
with a non-canonical kinetic term to General Relativity in $(2+1)$ dimensions.
After identifying a family of scalar Lagrangians that yield exact analytical
solutions in static and circularly symmetric scenarios, we classify the various
types of solutions and focus on a branch that yields asymptotically flat
geometries. We show that the solutions within such a branch can be divided in
two types, namely, naked singularities and nonsingular objects without a
center. In the latter, the energy density is localized around a maximum and
vanishes only at infinity and at an inner boundary. This boundary has vanishing
curvatures and cannot be reached by any time-like or null geodesic in finite
affine time. This allows us to consistently interpret such solutions as
nonsingular, lump-like, static compact scalar objects, whose eventual extension
to the $(3+1)$-dimensional context could provide structures of astrophysical
interest.
| [
{
"created": "Tue, 23 Apr 2024 10:08:08 GMT",
"version": "v1"
}
] | 2024-06-25 | [
[
"Maluf",
"Roberto V.",
""
],
[
"Mora-Pérez",
"Gerardo",
""
],
[
"Olmo",
"Gonzalo J.",
""
],
[
"Rubiera-Garcia",
"Diego",
""
]
] | We study the space-time geometry generated by coupling a free scalar field with a non-canonical kinetic term to General Relativity in $(2+1)$ dimensions. After identifying a family of scalar Lagrangians that yield exact analytical solutions in static and circularly symmetric scenarios, we classify the various types of solutions and focus on a branch that yields asymptotically flat geometries. We show that the solutions within such a branch can be divided in two types, namely, naked singularities and nonsingular objects without a center. In the latter, the energy density is localized around a maximum and vanishes only at infinity and at an inner boundary. This boundary has vanishing curvatures and cannot be reached by any time-like or null geodesic in finite affine time. This allows us to consistently interpret such solutions as nonsingular, lump-like, static compact scalar objects, whose eventual extension to the $(3+1)$-dimensional context could provide structures of astrophysical interest. |
2204.05047 | Mohammed Khalil | Mohammed Khalil, Alessandra Buonanno, Jan Steinhoff, Justin Vines | Energetics and scattering of gravitational two-body systems at fourth
post-Minkowskian order | 21 pages, 9 figures, 1 ancillary file. v2: Matches published version.
v3: correction in Appendix A | null | 10.1103/PhysRevD.106.024042 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Upcoming observational runs of the LIGO-Virgo-KAGRA collaboration, and future
gravitational-wave (GW) detectors on the ground and in space, require waveform
models more accurate than currently available. High-precision waveform models
can be developed by improving the analytical description of compact binary
dynamics and completing it with numerical-relativity (NR) information. Here, we
assess the accuracy of the recent results for the fourth post-Minkowskian (PM)
conservative dynamics through comparisons with NR simulations for the
circular-orbit binding energy and for the scattering angle. We obtain that the
4PM dynamics gives better agreement with NR than the 3PM dynamics, and that
while the 4PM approximation gives comparable results to the third
post-Newtonian (PN) approximation for bound orbits, it performs better for
scattering encounters. Furthermore, we incorporate the 4PM results in
effective-one-body (EOB) Hamiltonians, which improves the disagreement with NR
over the 4PM-expanded Hamiltonian from $\sim 40\%$ to $\sim 10\%$, or $\sim
3\%$ depending on the EOB gauge, for an equal-mass binary, two GW cycles before
merger. Finally, we derive a 4PN-EOB Hamiltonian for hyperbolic orbits, and
compare its predictions for the scattering angle to NR, and to the scattering
angle of a 4PN-EOB Hamiltonian computed for elliptic orbits.
| [
{
"created": "Mon, 11 Apr 2022 12:33:17 GMT",
"version": "v1"
},
{
"created": "Fri, 1 Jul 2022 15:47:32 GMT",
"version": "v2"
},
{
"created": "Tue, 23 Jan 2024 17:46:26 GMT",
"version": "v3"
}
] | 2024-01-24 | [
[
"Khalil",
"Mohammed",
""
],
[
"Buonanno",
"Alessandra",
""
],
[
"Steinhoff",
"Jan",
""
],
[
"Vines",
"Justin",
""
]
] | Upcoming observational runs of the LIGO-Virgo-KAGRA collaboration, and future gravitational-wave (GW) detectors on the ground and in space, require waveform models more accurate than currently available. High-precision waveform models can be developed by improving the analytical description of compact binary dynamics and completing it with numerical-relativity (NR) information. Here, we assess the accuracy of the recent results for the fourth post-Minkowskian (PM) conservative dynamics through comparisons with NR simulations for the circular-orbit binding energy and for the scattering angle. We obtain that the 4PM dynamics gives better agreement with NR than the 3PM dynamics, and that while the 4PM approximation gives comparable results to the third post-Newtonian (PN) approximation for bound orbits, it performs better for scattering encounters. Furthermore, we incorporate the 4PM results in effective-one-body (EOB) Hamiltonians, which improves the disagreement with NR over the 4PM-expanded Hamiltonian from $\sim 40\%$ to $\sim 10\%$, or $\sim 3\%$ depending on the EOB gauge, for an equal-mass binary, two GW cycles before merger. Finally, we derive a 4PN-EOB Hamiltonian for hyperbolic orbits, and compare its predictions for the scattering angle to NR, and to the scattering angle of a 4PN-EOB Hamiltonian computed for elliptic orbits. |
gr-qc/9701040 | Gungwong Kang | Gungwon Kang | Quantum Aspects of Ergoregion Instability | 20 pages, latex, 2 figures, epsfig.sty; one rather important argument
corrected, but main results remained, version to appear in Phys. Rev. D | Phys.Rev.D55:7563-7573,1997 | 10.1103/PhysRevD.55.7563 | RRI-97-2 | gr-qc hep-th | null | It has been known classically that a star with an ergoregion but no event
horizon is unstable to the emission of scalar, electromagnetic and
gravitational waves. This classical ergoregion instability is characterized by
complex frequency modes. We show how to canonically quantize a neutral scalar
field in the presence of such unstable modes by considering a simple model for
a rapidly rotating star. Some of interesting results is that there exists a
physically meaningful mode decomposition including unstable normal mode
solutions whose representation turns out to be a non-Fock-like Hilbert space. A
``particle" detector model placed in the in-vacuum state also shows that stars
with ergoregions give rise to a spontaneous energy radiation to spatial
infinity until ergoregions disappear.
| [
{
"created": "Sat, 18 Jan 1997 06:54:13 GMT",
"version": "v1"
},
{
"created": "Thu, 27 Mar 1997 12:18:17 GMT",
"version": "v2"
}
] | 2014-11-17 | [
[
"Kang",
"Gungwon",
""
]
] | It has been known classically that a star with an ergoregion but no event horizon is unstable to the emission of scalar, electromagnetic and gravitational waves. This classical ergoregion instability is characterized by complex frequency modes. We show how to canonically quantize a neutral scalar field in the presence of such unstable modes by considering a simple model for a rapidly rotating star. Some of interesting results is that there exists a physically meaningful mode decomposition including unstable normal mode solutions whose representation turns out to be a non-Fock-like Hilbert space. A ``particle" detector model placed in the in-vacuum state also shows that stars with ergoregions give rise to a spontaneous energy radiation to spatial infinity until ergoregions disappear. |
gr-qc/0506106 | Thomas Buchert | G.F.R. Ellis and T. Buchert | The universe seen at different scales | 17 pages; matches published version in Phys. Lett. A (Einstein
special issue) | Phys.Lett. A347 (2005) 38-46 | 10.1016/j.physleta.2005.06.087 | null | gr-qc astro-ph | null | A large-scale smoothed-out model of the universe ignores small-scale
inhomogeneities, but the averaged effects of those inhomogeneities may alter
both observational and dynamical relations at the larger scale. This article
discusses these effects, and comments briefly on the relation to gravitational
entropy.
| [
{
"created": "Tue, 21 Jun 2005 14:30:57 GMT",
"version": "v1"
},
{
"created": "Tue, 5 Jul 2005 08:35:08 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Ellis",
"G. F. R.",
""
],
[
"Buchert",
"T.",
""
]
] | A large-scale smoothed-out model of the universe ignores small-scale inhomogeneities, but the averaged effects of those inhomogeneities may alter both observational and dynamical relations at the larger scale. This article discusses these effects, and comments briefly on the relation to gravitational entropy. |
1111.0961 | Remigiusz Durka | R. Durka | Immirzi parameter and Noether charges in first order gravity | 17 pages, (new template, corrected typos), to appear in Proceedings
of "Quantum Theory and Symmetries 7" Prague, Journal of Physics: Conference
Series (JPCS) | null | 10.1088/1742-6596/343/1/012032 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The framework of SO(3,2) constrained BF theory applied to gravity makes it
possible to generalize formulas for gravitational diffeomorphic Noether charges
(mass, angular momentum, and entropy). It extends Wald's approach to the case
of first order gravity with a negative cosmological constant, the Holst
modification and the topological terms (Nieh-Yan, Euler, and Pontryagin).
Topological invariants play essential role contributing to the boundary terms
in the regularization scheme for the asymptotically AdS spacetimes, so that the
differentiability of the action is automatically secured. Intriguingly, it
turns out that the black hole thermodynamics does not depend on the Immirzi
parameter for the AdS-Schwarzschild, AdS-Kerr, and topological black holes,
whereas a nontrivial modification appears for the AdS-Taub-NUT spacetime, where
it impacts not only the entropy, but also the total mass.
| [
{
"created": "Thu, 3 Nov 2011 19:53:13 GMT",
"version": "v1"
},
{
"created": "Tue, 8 Nov 2011 20:51:14 GMT",
"version": "v2"
}
] | 2015-06-03 | [
[
"Durka",
"R.",
""
]
] | The framework of SO(3,2) constrained BF theory applied to gravity makes it possible to generalize formulas for gravitational diffeomorphic Noether charges (mass, angular momentum, and entropy). It extends Wald's approach to the case of first order gravity with a negative cosmological constant, the Holst modification and the topological terms (Nieh-Yan, Euler, and Pontryagin). Topological invariants play essential role contributing to the boundary terms in the regularization scheme for the asymptotically AdS spacetimes, so that the differentiability of the action is automatically secured. Intriguingly, it turns out that the black hole thermodynamics does not depend on the Immirzi parameter for the AdS-Schwarzschild, AdS-Kerr, and topological black holes, whereas a nontrivial modification appears for the AdS-Taub-NUT spacetime, where it impacts not only the entropy, but also the total mass. |
1505.03551 | Edward Anderson | Edward Anderson | Explicit partial and functional differential equations for beables or
observables | 9 pages including 4 figures: minor presentational upgrades and
further references added | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide explicit partial differential equations - in finite cases - and
functional differential equations - in field-theoretic cases - which determine
observables or beables in the senses of Kucha\v{r} and of Dirac. These cover a
wide range of relational mechanics models as well as Electromagnetism,
Yang--Mills Theory and General Relativity. We give an underlying reason why
pure-configuration Kucha\v{r} observables are already well-known: various types
of shape, E-fields, B-fields, loops and 3-geometries. The partial differential
equations or functional differential equations for pure-momentum observables
are also posed, as are those for observables which have a mixture of
configuration and momentum functional dependence.
| [
{
"created": "Wed, 13 May 2015 20:58:41 GMT",
"version": "v1"
},
{
"created": "Wed, 5 Dec 2018 23:30:15 GMT",
"version": "v2"
}
] | 2018-12-07 | [
[
"Anderson",
"Edward",
""
]
] | We provide explicit partial differential equations - in finite cases - and functional differential equations - in field-theoretic cases - which determine observables or beables in the senses of Kucha\v{r} and of Dirac. These cover a wide range of relational mechanics models as well as Electromagnetism, Yang--Mills Theory and General Relativity. We give an underlying reason why pure-configuration Kucha\v{r} observables are already well-known: various types of shape, E-fields, B-fields, loops and 3-geometries. The partial differential equations or functional differential equations for pure-momentum observables are also posed, as are those for observables which have a mixture of configuration and momentum functional dependence. |
gr-qc/0603082 | Roldao da Rocha | Roldao da Rocha and E. Capelas de Oliveira | Conformal Klein-Gordon equations and quasinormal modes | 13 pages, 10 figures | Int.J.Theor.Phys.46:301-317,2007 | 10.1007/s10773-006-9238-5 | null | gr-qc | null | Using conformal coordinates associated with conformal relativity --
associated with de Sitter spacetime homeomorphic projection into Minkowski
spacetime -- we obtain a conformal Klein-Gordon partial differential equation,
which is intimately related to the production of quasi-normal modes (QNMs)
oscillations, in the context of electromagnetic and/or gravitational
perturbations around, e.g., black holes. While QNMs arise as the solution of a
wave-like equation with a Poschl-Teller potential, here we deduce and
analytically solve a conformal radial d'Alembert-like equation, from which we
derive QNMs formal solutions, in a proposed alternative to more completely
describe QNMs. As a by-product we show that this radial equation can be
identified with a Schrodinger-like equation in which the potential is exactly
the second Poschl-Teller potential, and it can shed some new light on the
investigations concerning QNMs.
| [
{
"created": "Mon, 20 Mar 2006 20:37:35 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"da Rocha",
"Roldao",
""
],
[
"de Oliveira",
"E. Capelas",
""
]
] | Using conformal coordinates associated with conformal relativity -- associated with de Sitter spacetime homeomorphic projection into Minkowski spacetime -- we obtain a conformal Klein-Gordon partial differential equation, which is intimately related to the production of quasi-normal modes (QNMs) oscillations, in the context of electromagnetic and/or gravitational perturbations around, e.g., black holes. While QNMs arise as the solution of a wave-like equation with a Poschl-Teller potential, here we deduce and analytically solve a conformal radial d'Alembert-like equation, from which we derive QNMs formal solutions, in a proposed alternative to more completely describe QNMs. As a by-product we show that this radial equation can be identified with a Schrodinger-like equation in which the potential is exactly the second Poschl-Teller potential, and it can shed some new light on the investigations concerning QNMs. |
gr-qc/0003116 | Philippe Droz-Vincent | Philippe Droz-Vincent (Univ. P. et M. Curie) | Mode solutions of the Klein-Gordon equation in warped spacetimes | 20 pages, LaTeX file, nofigure | Class.Quant.Grav. 18 (2001) 207-224 | 10.1088/0264-9381/18/2/301 | null | gr-qc | null | In order to reduce the Klein-Gordon equation (with minimal coupling), we
introduce a generalization of the so-called "mode solutions" that are
well-known in the special case of a Robertson-Walker universe. After separation
of the variables, we end up with a partial differential equation in lower
dimension. A reduced version of the Gordon current arises and is conserved.
When the first factor-manifold is Lorentzian, distinct modes appear as mutually
orthogonal in the sense of the sesquilinear form obtained from the customary
Gordon current. Moreover, a sesquilinear form is defined on the space of
solutions to the reduced equation. Extension of this picture to curvature
coupling is possible when the second factor-manifold has a constant scalar
curvature.
| [
{
"created": "Fri, 31 Mar 2000 18:30:18 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Droz-Vincent",
"Philippe",
"",
"Univ. P. et M. Curie"
]
] | In order to reduce the Klein-Gordon equation (with minimal coupling), we introduce a generalization of the so-called "mode solutions" that are well-known in the special case of a Robertson-Walker universe. After separation of the variables, we end up with a partial differential equation in lower dimension. A reduced version of the Gordon current arises and is conserved. When the first factor-manifold is Lorentzian, distinct modes appear as mutually orthogonal in the sense of the sesquilinear form obtained from the customary Gordon current. Moreover, a sesquilinear form is defined on the space of solutions to the reduced equation. Extension of this picture to curvature coupling is possible when the second factor-manifold has a constant scalar curvature. |
gr-qc/9611040 | Kim Sang Pyo | Sang Pyo Kim(Kunsan National University, Dept. of Physics) | Problem of Unitarity and Quantum Corrections in Semiclassical Quantum
Gravity | Replaced with the version published in PRD | Phys.Rev.D55:7511-7517,1997 | 10.1103/PhysRevD.55.7511 | null | gr-qc hep-th | null | Using both the Born-Oppenheimer idea and the de Broglie-Bohm interpretation
of wavefunction we represent in a different way the semiclassical quantum
gravity from the Wheeler-DeWitt equation in an oscillating regime which can
preserve completely the unitary quantum evolution of a matter field at the
expense of a nonlinear gravitational field equation, but has the same
asymptotic limit as the others. We apply the de Broglie-Bohm interpretation to
the nonlinear gravitational field equation to develop a perturbation method to
find the quantum corrections of a matter field to the gravity. The
semiclassical Einstein equation with the quantum corrections is found for a
minimal quantum FRW cosmological model.
| [
{
"created": "Thu, 14 Nov 1996 11:55:25 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Nov 1996 07:46:07 GMT",
"version": "v2"
},
{
"created": "Wed, 19 Feb 1997 05:24:01 GMT",
"version": "v3"
},
{
"created": "Thu, 12 Jun 1997 08:27:32 GMT",
"version": "v4"
}
] | 2014-11-17 | [
[
"Kim",
"Sang Pyo",
"",
"Kunsan National University, Dept. of Physics"
]
] | Using both the Born-Oppenheimer idea and the de Broglie-Bohm interpretation of wavefunction we represent in a different way the semiclassical quantum gravity from the Wheeler-DeWitt equation in an oscillating regime which can preserve completely the unitary quantum evolution of a matter field at the expense of a nonlinear gravitational field equation, but has the same asymptotic limit as the others. We apply the de Broglie-Bohm interpretation to the nonlinear gravitational field equation to develop a perturbation method to find the quantum corrections of a matter field to the gravity. The semiclassical Einstein equation with the quantum corrections is found for a minimal quantum FRW cosmological model. |
2105.04039 | Shohei Aoyama | Shohei Aoyama, Daisuke Yamauchi, Maresuke Shiraishi and Masami Ouchi | Gaia 400,894 QSO constraint on the energy density of low-frequency
gravitational waves | Submitted to Physical Review D | null | null | null | gr-qc astro-ph.CO astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Low frequency gravitational waves (GWs) are keys to understanding
cosmological inflation and super massive blackhole (SMBH) formation via
blackhole mergers, while it is difficult to identify the low frequency GWs with
ground-based GW experiments such as the advanced LIGO (aLIGO) and VIRGO due to
the seismic noise. Although quasi-stellar object (QSO) proper motions produced
by the low frequency GWs are measured by pioneering studies of very long
baseline interferometry (VLBI) observations with good positional accuracy, the
low frequency GWs are not strongly constrained by the small statistics with 711
QSOs (Darling et al. 2018). Here we present the proper motion field map of
400,894 QSOs of the Sloan Digital Sky Survey (SDSS) with optical {\it Gaia}
EDR3 proper motion measurements whose positional accuracy is $< 0.4$
milli-arcsec comparable with the one of the radio VLBI observations. We obtain
the best-fit spherical harmonics with the typical field strength of
$\mathcal{O}(0.1)\, \mu$arcsec, and place a tight constraint on the energy
density of GWs, $\Omega_{\rm gw}=(0.964 \pm 3.804) \times 10^{-4}$ (95 \%
confidence level), that is significantly stronger than the one of the previous
VLBI study by two orders of magnitude at the low frequency regime of $f
<10^{-9}\,{\rm [Hz]}\simeq (30\,{\rm yr})^{-1}$ unexplored by the pulsar timing
technique. Our upper limit rules out the existence of SMBH binary systems at
the distance $r < 400$ kpc from the Earth where the Milky Way center and local
group galaxies are included. Demonstrating the limit given by our optical QSO
study, we claim that astrometric satellite data including the forthcoming {\it
Gaia} DR5 data with small systematic errors are powerful to constrain low
frequency GWs.
| [
{
"created": "Sun, 9 May 2021 22:26:10 GMT",
"version": "v1"
}
] | 2021-05-11 | [
[
"Aoyama",
"Shohei",
""
],
[
"Yamauchi",
"Daisuke",
""
],
[
"Shiraishi",
"Maresuke",
""
],
[
"Ouchi",
"Masami",
""
]
] | Low frequency gravitational waves (GWs) are keys to understanding cosmological inflation and super massive blackhole (SMBH) formation via blackhole mergers, while it is difficult to identify the low frequency GWs with ground-based GW experiments such as the advanced LIGO (aLIGO) and VIRGO due to the seismic noise. Although quasi-stellar object (QSO) proper motions produced by the low frequency GWs are measured by pioneering studies of very long baseline interferometry (VLBI) observations with good positional accuracy, the low frequency GWs are not strongly constrained by the small statistics with 711 QSOs (Darling et al. 2018). Here we present the proper motion field map of 400,894 QSOs of the Sloan Digital Sky Survey (SDSS) with optical {\it Gaia} EDR3 proper motion measurements whose positional accuracy is $< 0.4$ milli-arcsec comparable with the one of the radio VLBI observations. We obtain the best-fit spherical harmonics with the typical field strength of $\mathcal{O}(0.1)\, \mu$arcsec, and place a tight constraint on the energy density of GWs, $\Omega_{\rm gw}=(0.964 \pm 3.804) \times 10^{-4}$ (95 \% confidence level), that is significantly stronger than the one of the previous VLBI study by two orders of magnitude at the low frequency regime of $f <10^{-9}\,{\rm [Hz]}\simeq (30\,{\rm yr})^{-1}$ unexplored by the pulsar timing technique. Our upper limit rules out the existence of SMBH binary systems at the distance $r < 400$ kpc from the Earth where the Milky Way center and local group galaxies are included. Demonstrating the limit given by our optical QSO study, we claim that astrometric satellite data including the forthcoming {\it Gaia} DR5 data with small systematic errors are powerful to constrain low frequency GWs. |
2304.12278 | Antonino Marciano | Xuan-Lin Su, Alioscia Hamma and Antonino Marciano | On the irrelevance of the scrambling power of gravity for black hole
radiation | 90 pages | null | null | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Black holes are a recently observed theoretical prediction of General
Relativity, characterized by event horizons, from which information cannot
escape. Examined through the lenses of quantum mechanics, they can radiate at a
definite temperature inverse to their mass and horizon radius. Hawking
radiation, whose spectrum was calculated considering particles scattering off
black holes, is connected to the paradox of the loss of information falling
into them. Information can become non-fungible, due to scrambling. We
demonstrate this feature not to be restricted to curved space-times: soft
radiation scattering in a flat space-time does scramble information as well. To
this end, we compute the scrambling of information through the tripartite
mutual information in a scattering process off a black hole and compare it with
the flat space-time analog. We show that the scrambling power of the
gravitational field of a black hole is negligible with respect to the
scrambling power of flat space-time.
| [
{
"created": "Mon, 24 Apr 2023 17:17:28 GMT",
"version": "v1"
},
{
"created": "Wed, 3 May 2023 12:26:28 GMT",
"version": "v2"
}
] | 2023-05-04 | [
[
"Su",
"Xuan-Lin",
""
],
[
"Hamma",
"Alioscia",
""
],
[
"Marciano",
"Antonino",
""
]
] | Black holes are a recently observed theoretical prediction of General Relativity, characterized by event horizons, from which information cannot escape. Examined through the lenses of quantum mechanics, they can radiate at a definite temperature inverse to their mass and horizon radius. Hawking radiation, whose spectrum was calculated considering particles scattering off black holes, is connected to the paradox of the loss of information falling into them. Information can become non-fungible, due to scrambling. We demonstrate this feature not to be restricted to curved space-times: soft radiation scattering in a flat space-time does scramble information as well. To this end, we compute the scrambling of information through the tripartite mutual information in a scattering process off a black hole and compare it with the flat space-time analog. We show that the scrambling power of the gravitational field of a black hole is negligible with respect to the scrambling power of flat space-time. |
gr-qc/9803099 | Masaru Siino | Masaru Siino | Topological Appearance of Event Horizon: What Is the Topology of the
Event Horizon That We Can See? | 53 pages, revtex, Published in Prog. Theo. Phys. vol.99, 13 figures | Prog.Theor.Phys. 99 (1998) 1-32 | 10.1143/PTP.99.1 | null | gr-qc | null | The topology of the event horizon (TOEH) is usually believed to be a sphere.
Nevertheless, some numerical simulations of gravitational collapse with a
toroidal event horizon or the collision of event horizons are reported.
Considering the indifferentiability of the event horizon (EH), we see that such
non-trivial TOEHs are caused by the set of endpoints (the crease set) of the
EH. The two-dimensional (one-dimensional) crease set is related to the toroidal
EH (the coalescence of the EH). Furthermore, examining the stability of the
structure of the endpoints, it becomes clear that the spherical TOEH is
unstable under linear perturbation. On the other hand, a discussion based on
catastrophe theory reveals that the TOEH with handles is stable and generic.
Also, the relation between the TOEH and the hoop conjecture is discussed. It is
shown that the Kastor-Traschen solution is regarded as a good example of the
hoop conjecture by the discussion of its TOEH. We further conjecture that a
non-trivial TOEH can be smoothed out by rough observation in its mass scale.
| [
{
"created": "Tue, 31 Mar 1998 13:17:59 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Siino",
"Masaru",
""
]
] | The topology of the event horizon (TOEH) is usually believed to be a sphere. Nevertheless, some numerical simulations of gravitational collapse with a toroidal event horizon or the collision of event horizons are reported. Considering the indifferentiability of the event horizon (EH), we see that such non-trivial TOEHs are caused by the set of endpoints (the crease set) of the EH. The two-dimensional (one-dimensional) crease set is related to the toroidal EH (the coalescence of the EH). Furthermore, examining the stability of the structure of the endpoints, it becomes clear that the spherical TOEH is unstable under linear perturbation. On the other hand, a discussion based on catastrophe theory reveals that the TOEH with handles is stable and generic. Also, the relation between the TOEH and the hoop conjecture is discussed. It is shown that the Kastor-Traschen solution is regarded as a good example of the hoop conjecture by the discussion of its TOEH. We further conjecture that a non-trivial TOEH can be smoothed out by rough observation in its mass scale. |
gr-qc/0701118 | Ion I. Cotaescu | Ion I Cot\u{a}escu | Dirac fermions in de Sitter and anti-de Sitter backgrounds | 59 pages | Rom.J.Phys.52:895-940,2007 | null | null | gr-qc | null | Starting with a new theory of symmetries generated by isometries in field
theories with spin, one finds the generators of the spinor representation in
backgrounds with a given symmetry. In this manner one obtains a collection of
conserved operators from which one can chose the complete sets of commuting
operators defining quantum modes. In this framework, the quantum modes of the
free Dirac field on de Sitter or anti-de Sitter spacetimes can be completely
derived in static or moving charts. One presents the discrete quantum modes, in
the central static charts of the anti-de Sitter spacetime, whose eigenspinors
can be normalized. The consequence is that the second quantization can be done
in this case in canonical manner. For the free Dirac field on de Sitter
manifolds this can not be done in static charts being forced to consider the
moving ones. The quantum modes of the free Dirac field in these charts are used
for writing down the quantum Dirac field and its one-particle operators.
| [
{
"created": "Mon, 22 Jan 2007 11:44:35 GMT",
"version": "v1"
},
{
"created": "Mon, 5 Feb 2007 09:48:26 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Cotăescu",
"Ion I",
""
]
] | Starting with a new theory of symmetries generated by isometries in field theories with spin, one finds the generators of the spinor representation in backgrounds with a given symmetry. In this manner one obtains a collection of conserved operators from which one can chose the complete sets of commuting operators defining quantum modes. In this framework, the quantum modes of the free Dirac field on de Sitter or anti-de Sitter spacetimes can be completely derived in static or moving charts. One presents the discrete quantum modes, in the central static charts of the anti-de Sitter spacetime, whose eigenspinors can be normalized. The consequence is that the second quantization can be done in this case in canonical manner. For the free Dirac field on de Sitter manifolds this can not be done in static charts being forced to consider the moving ones. The quantum modes of the free Dirac field in these charts are used for writing down the quantum Dirac field and its one-particle operators. |
1402.0718 | Luciano Vanzo | Giovanni Acquaviva, Luca Bonetti, Luciano Vanzo and Sergio Zerbini | Vacuum fluctuation of conformally coupled scalar field in FLRW
space-times | 17 pages, standard LateX document | Phys. Rev. D 89, 084031 (2014) | 10.1103/PhysRevD.89.084031 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The regularized vacuum fluctuation related to a conformally coupled massless
scalar field defined on a space-time with dynamical horizon is computed with
respect a radially moving observer in a generic flat Friedmann-Robertson-Walker
space-time. Two simple measurement prescriptions are given in order to remove
the ambiguity associated with the short distance singularity of the correlation
function. In some cases, it turns out that one is dealing with a quantum
thermometer, recovering a proposal due to Buchholzet al. in order to determine
local temperature in the framework of quantum field theory. In general, by
arranging the detector so that it does not register for inertial motion in flat
space, the regularized quantum fluctuation may be used as a probe of space-time
geometry and, in particular, may provide informations on the Hubble parameter.
As an aside, it is not possible in general to fully decouple the effect of the
detector motion from the universe expansion, a fact that could be interpreted
as a kind of Machian effect which can be traced back to the worldwide nature of
the vacuum.
| [
{
"created": "Tue, 4 Feb 2014 13:01:44 GMT",
"version": "v1"
}
] | 2014-04-23 | [
[
"Acquaviva",
"Giovanni",
""
],
[
"Bonetti",
"Luca",
""
],
[
"Vanzo",
"Luciano",
""
],
[
"Zerbini",
"Sergio",
""
]
] | The regularized vacuum fluctuation related to a conformally coupled massless scalar field defined on a space-time with dynamical horizon is computed with respect a radially moving observer in a generic flat Friedmann-Robertson-Walker space-time. Two simple measurement prescriptions are given in order to remove the ambiguity associated with the short distance singularity of the correlation function. In some cases, it turns out that one is dealing with a quantum thermometer, recovering a proposal due to Buchholzet al. in order to determine local temperature in the framework of quantum field theory. In general, by arranging the detector so that it does not register for inertial motion in flat space, the regularized quantum fluctuation may be used as a probe of space-time geometry and, in particular, may provide informations on the Hubble parameter. As an aside, it is not possible in general to fully decouple the effect of the detector motion from the universe expansion, a fact that could be interpreted as a kind of Machian effect which can be traced back to the worldwide nature of the vacuum. |
1505.06123 | Paul Tod | Paul Tod | Some geometry of de Sitter space | 10 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this expository note, I present some basic geometric and twistor theoretic
facts about de Sitter space leading up to a discussion of Penrose's quasi-local
mass construction for linear gravity theory in the de Sitter background. The
corresponding results for Minkowski space and anti--de Sitter space are
familiar and can be found in \cite{PR} or \cite{HT} for the former and
\cite{KT} for the latter. Some of the formulas given here are also quite
familiar, but some are thought to be new and it is convenient to have these
facts collected in one place.
| [
{
"created": "Fri, 22 May 2015 15:35:00 GMT",
"version": "v1"
}
] | 2015-05-25 | [
[
"Tod",
"Paul",
""
]
] | In this expository note, I present some basic geometric and twistor theoretic facts about de Sitter space leading up to a discussion of Penrose's quasi-local mass construction for linear gravity theory in the de Sitter background. The corresponding results for Minkowski space and anti--de Sitter space are familiar and can be found in \cite{PR} or \cite{HT} for the former and \cite{KT} for the latter. Some of the formulas given here are also quite familiar, but some are thought to be new and it is convenient to have these facts collected in one place. |
1611.02514 | Roberto Peron Dr. | Carmen Pardini, Luciano Anselmo, David Massimo Lucchesi, Roberto Peron | Estimation of the Perturbing Accelerations Induced on the LARES
Satellite by Neutral Atmosphere Drag | null | null | null | null | gr-qc astro-ph.EP physics.space-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The laser-ranged satellite LARES is expected to provide new refined
measurements of relativistic physics, as well as significant contributions to
space geodesy and geophysics. The very low area-to-mass ratio of this passive
and dense satellite was chosen to reduce as much as possible the disturbing
effects of non-gravitational perturbations. However, because of its height,
about 1450 km compared with about 5800-5900 km for the two LAGEOS satellites,
LARES is exposed to a much stronger drag due to neutral atmosphere. From a
precise orbit determination, analyzing the laser ranging normal points of LARES
over a time span of about 3.7 years, it was found an average semi-major axis
decay rate of -0.999 m per year, corresponding to a non-conservative net force
with a mean along-track acceleration of -1.444 x 10^-11 m/s^2. By means of a
modified version of the SATRAP (ISTI/CNR) code, the neutral drag perturbation
acting on LARES was evaluated over the same time span, taking into account the
real evolution of solar and geomagnetic activities, with five thermospheric
density models. All of them were able to model most of the observed semi-major
axis decay, with differences among the average drag coefficients smaller than
10%. A further independent check carried out analyzing the orbital decay of a
passive spherical satellite (Ajisai) just 40 km higher than LARES, it was then
concluded that some of the currently best models developed for neutral
atmosphere, within their uncertainties and range of applicability, were able to
account for most (about 98.6%) of the observed semi-major axis decay of LARES.
Finally, after modeling the neutral atmosphere drag, a residual semi-major axis
decay, corresponding to an average along-track acceleration of about -2 x
10^-13 m/s^2 (i.e. about 1/72 of neutral drag), was detected as well.
| [
{
"created": "Tue, 8 Nov 2016 13:35:43 GMT",
"version": "v1"
}
] | 2016-11-09 | [
[
"Pardini",
"Carmen",
""
],
[
"Anselmo",
"Luciano",
""
],
[
"Lucchesi",
"David Massimo",
""
],
[
"Peron",
"Roberto",
""
]
] | The laser-ranged satellite LARES is expected to provide new refined measurements of relativistic physics, as well as significant contributions to space geodesy and geophysics. The very low area-to-mass ratio of this passive and dense satellite was chosen to reduce as much as possible the disturbing effects of non-gravitational perturbations. However, because of its height, about 1450 km compared with about 5800-5900 km for the two LAGEOS satellites, LARES is exposed to a much stronger drag due to neutral atmosphere. From a precise orbit determination, analyzing the laser ranging normal points of LARES over a time span of about 3.7 years, it was found an average semi-major axis decay rate of -0.999 m per year, corresponding to a non-conservative net force with a mean along-track acceleration of -1.444 x 10^-11 m/s^2. By means of a modified version of the SATRAP (ISTI/CNR) code, the neutral drag perturbation acting on LARES was evaluated over the same time span, taking into account the real evolution of solar and geomagnetic activities, with five thermospheric density models. All of them were able to model most of the observed semi-major axis decay, with differences among the average drag coefficients smaller than 10%. A further independent check carried out analyzing the orbital decay of a passive spherical satellite (Ajisai) just 40 km higher than LARES, it was then concluded that some of the currently best models developed for neutral atmosphere, within their uncertainties and range of applicability, were able to account for most (about 98.6%) of the observed semi-major axis decay of LARES. Finally, after modeling the neutral atmosphere drag, a residual semi-major axis decay, corresponding to an average along-track acceleration of about -2 x 10^-13 m/s^2 (i.e. about 1/72 of neutral drag), was detected as well. |
1712.01654 | De-Chang Dai | De-Chang Dai, Chunyu Lu | Can $\Lambda$CDM model reproduce MOND-like behavior? | 9 figures, accepted by Phys. Rev. D | null | 10.1103/PhysRevD.96.124016 | null | gr-qc astro-ph.GA hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is usually believed that MOND can describe the galactic rotational curves
with only baryonic matter and without any dark matter very well, while the
$\Lambda$CDM model is expected to have difficulty in reproducing MOND-like
behavior. Here, we use EAGLE's data to learn whether the $\Lambda$CDM model can
reproduce MOND-like behavior. EAGLE's simulation result clearly reproduces the
MOND-like behavior for $a_b\gtrapprox 10^{-12}\text{m/s}^2$ at $z=0$, although
the acceleration constant, $a_0$, is a little larger than the observational
data indicate. We find that $a_0$ increases with the redshift in a way
different from what Milgrom proposed ($a_0\propto H$). Therefore, while galaxy
rotation curves can be fitted by MOND's empirical function in the $\Lambda$CDM
model, there is no clear connection between $a_0$ and the Hubble constant. We
also find that $a_0$ at $z\gtrapprox 1$ is well separated from $a_0$ at $z=0$.
Once we have enough galaxies observed at high redshifts, we will be able to
rule out the modified gravity model based on MOND-like empirical function with
a z-independent $a_0$.
| [
{
"created": "Fri, 1 Dec 2017 23:39:22 GMT",
"version": "v1"
}
] | 2018-01-17 | [
[
"Dai",
"De-Chang",
""
],
[
"Lu",
"Chunyu",
""
]
] | It is usually believed that MOND can describe the galactic rotational curves with only baryonic matter and without any dark matter very well, while the $\Lambda$CDM model is expected to have difficulty in reproducing MOND-like behavior. Here, we use EAGLE's data to learn whether the $\Lambda$CDM model can reproduce MOND-like behavior. EAGLE's simulation result clearly reproduces the MOND-like behavior for $a_b\gtrapprox 10^{-12}\text{m/s}^2$ at $z=0$, although the acceleration constant, $a_0$, is a little larger than the observational data indicate. We find that $a_0$ increases with the redshift in a way different from what Milgrom proposed ($a_0\propto H$). Therefore, while galaxy rotation curves can be fitted by MOND's empirical function in the $\Lambda$CDM model, there is no clear connection between $a_0$ and the Hubble constant. We also find that $a_0$ at $z\gtrapprox 1$ is well separated from $a_0$ at $z=0$. Once we have enough galaxies observed at high redshifts, we will be able to rule out the modified gravity model based on MOND-like empirical function with a z-independent $a_0$. |
gr-qc/9408005 | Francois Englert | F.Englert | The Black Hole History in Tamed Vacuum | 29 pages, ULB-TH 15/94 phyzzx file | null | null | null | gr-qc hep-th | null | Quantum physics at scales large compared to the Planck scale is described in
the framework of classical space-time geometries. A criterion for selecting
these backgrounds out of quantized gravity is proposed. It leads to an
instability of the black-hole geometry, as experienced by motion across the
horizon, against emission of Hawking quanta. A phenomenological treatment of
the evaporation process perceived by external observers who do not cross the
event horizon is presented. Evaporation occurs within a topologically trivial
``achronon" geometrical background devoid of horizons and singularities
describing a collapse frozen up to decay time scales. It is ignited as in the
conventional theory from pair creation out of the vacuum of the collapsing star
of mass $M$, but after a time of order $M\ln M$ the source of thermal radiation
shifts gradually to the star itself. This allows for a unitary evolution except
possibly for exponentially small background transition amplitudes. The emerging
picture is compared with approaches of t'Hooft and Susskind and the problem of
its overall quantum consistency is evoked. (Figures available upon request)
| [
{
"created": "Wed, 3 Aug 1994 13:16:15 GMT",
"version": "v1"
}
] | 2009-09-25 | [
[
"Englert",
"F.",
""
]
] | Quantum physics at scales large compared to the Planck scale is described in the framework of classical space-time geometries. A criterion for selecting these backgrounds out of quantized gravity is proposed. It leads to an instability of the black-hole geometry, as experienced by motion across the horizon, against emission of Hawking quanta. A phenomenological treatment of the evaporation process perceived by external observers who do not cross the event horizon is presented. Evaporation occurs within a topologically trivial ``achronon" geometrical background devoid of horizons and singularities describing a collapse frozen up to decay time scales. It is ignited as in the conventional theory from pair creation out of the vacuum of the collapsing star of mass $M$, but after a time of order $M\ln M$ the source of thermal radiation shifts gradually to the star itself. This allows for a unitary evolution except possibly for exponentially small background transition amplitudes. The emerging picture is compared with approaches of t'Hooft and Susskind and the problem of its overall quantum consistency is evoked. (Figures available upon request) |
1511.04149 | Takahisa Igata | Takahisa Igata, Shinya Tomizawa | Gravitational two solitons in Levi-Civita spacetime | 17 pages, 4 figures, version to be published in Classical and Quantum
Gravity | Class. Quant. Grav. 33, 185005 (2016) | 10.1088/0264-9381/33/18/185005 | RUP-15-25 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Applying the Pomeransky inverse scattering method to the four-dimensional
vacuum Einstein equations and using the Levi-Civita solution as a seed, we
construct a two-soliton solution with cylindrical symmetry. In our previous
work, we constructed the one-soliton solution with a real pole and showed that
the singularities that the Levi-Civita background has on an axis can be removed
by the choice of certain special parameters, but it still has unavoidable null
singularities, as usual one-solitons do. In this work, we show that for the
two-soliton solutions, any singularities can be removed by suitable
parameter-setting and such solutions describe the propagation of gravitational
wave packets. Moreover, in terms of the two-soliton solutions, we mention a
time shift phenomenon, the coalescence and the split of solitons as the
nonlinear effect of gravitational waves.
| [
{
"created": "Fri, 13 Nov 2015 03:27:51 GMT",
"version": "v1"
},
{
"created": "Fri, 2 Sep 2016 02:21:46 GMT",
"version": "v2"
}
] | 2016-09-05 | [
[
"Igata",
"Takahisa",
""
],
[
"Tomizawa",
"Shinya",
""
]
] | Applying the Pomeransky inverse scattering method to the four-dimensional vacuum Einstein equations and using the Levi-Civita solution as a seed, we construct a two-soliton solution with cylindrical symmetry. In our previous work, we constructed the one-soliton solution with a real pole and showed that the singularities that the Levi-Civita background has on an axis can be removed by the choice of certain special parameters, but it still has unavoidable null singularities, as usual one-solitons do. In this work, we show that for the two-soliton solutions, any singularities can be removed by suitable parameter-setting and such solutions describe the propagation of gravitational wave packets. Moreover, in terms of the two-soliton solutions, we mention a time shift phenomenon, the coalescence and the split of solitons as the nonlinear effect of gravitational waves. |
2406.19442 | Gregorio Carullo | Gregorio Carullo | Ringdown amplitudes of nonspinning eccentric binaries | 20 pages, 11 figures | v2: added 320 mode and public data release;
journal submitted version | null | null | Virgo document number: VIR-0579A-24 | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Closed-form expressions for the ringdown complex amplitudes of nonspinning
unequal-mass binaries in arbitrarily eccentric orbits are presented. They are
built upon 237 numerical simulations contained within the RIT catalog, through
the parameterisation introduced in [Phys. Rev. Lett. 132, 101401]. Global fits
for the complex amplitudes, associated to linear quasinormal mode frequencies
of the dominant ringdown modes, are obtained in a factorised form immediately
applicable to any existing quasi-circular model. Similarly to merger
amplitudes, ringdown ones increase by more than 50% compared to the circular
case for high impact parameters (medium eccentricities), while strongly
suppressed in the low impact parameter (highly eccentric) limit. Such reduction
can be explained by a transition between an "orbital-type" and an "infall-type"
dynamics. The amplitudes (phases) fits accuracy lies around a few percent
(deciradians) for the majority of the dataset, comparable to the accuracy of
current state-of-the-art quasi-circular ringdown models, and well within
current statistical errors of current LIGO-Virgo-Kagra ringdown observations.
These expressions constitute another building block towards the construction of
complete general-relativistic inspiral-merger-ringdown semi-analytical
templates, and allow to extend numerically-informed spectroscopic analyses
beyond the circular limit. Such generalisations are key to achieve accurate
inference of compact binaries astrophysical properties, and tame astrophysical
systematics within observational investigations of strong-field general
relativistic dynamics.
| [
{
"created": "Thu, 27 Jun 2024 18:00:01 GMT",
"version": "v1"
},
{
"created": "Thu, 15 Aug 2024 15:43:12 GMT",
"version": "v2"
}
] | 2024-08-16 | [
[
"Carullo",
"Gregorio",
""
]
] | Closed-form expressions for the ringdown complex amplitudes of nonspinning unequal-mass binaries in arbitrarily eccentric orbits are presented. They are built upon 237 numerical simulations contained within the RIT catalog, through the parameterisation introduced in [Phys. Rev. Lett. 132, 101401]. Global fits for the complex amplitudes, associated to linear quasinormal mode frequencies of the dominant ringdown modes, are obtained in a factorised form immediately applicable to any existing quasi-circular model. Similarly to merger amplitudes, ringdown ones increase by more than 50% compared to the circular case for high impact parameters (medium eccentricities), while strongly suppressed in the low impact parameter (highly eccentric) limit. Such reduction can be explained by a transition between an "orbital-type" and an "infall-type" dynamics. The amplitudes (phases) fits accuracy lies around a few percent (deciradians) for the majority of the dataset, comparable to the accuracy of current state-of-the-art quasi-circular ringdown models, and well within current statistical errors of current LIGO-Virgo-Kagra ringdown observations. These expressions constitute another building block towards the construction of complete general-relativistic inspiral-merger-ringdown semi-analytical templates, and allow to extend numerically-informed spectroscopic analyses beyond the circular limit. Such generalisations are key to achieve accurate inference of compact binaries astrophysical properties, and tame astrophysical systematics within observational investigations of strong-field general relativistic dynamics. |
gr-qc/9309003 | Jorge Pullin | Jorge Pullin (Editor) | MATTERS OF GRAVITY, a newsletter for the gravity community, number 2 | Number 2 Fall 1993 (18 pages plain TeX) | null | null | null | gr-qc | null | Table of contents:
Editorial 1
Correspondents 3
Some recent work in general relativistic Astrophysics 4
Two dimensional black holes 6
Resonant-mass gravitational wave detectors: an update 8
Universality and scaling in gravitational collapse 9
Gravitational Wave memories upgraded 11
Conference report: quantum aspects of black holes 13
Conference report: knots and quantum gravity 14
Conference report: deterministic chaos in GR 17
| [
{
"created": "Thu, 2 Sep 1993 03:22:13 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Pullin",
"Jorge",
"",
"Editor"
]
] | Table of contents: Editorial 1 Correspondents 3 Some recent work in general relativistic Astrophysics 4 Two dimensional black holes 6 Resonant-mass gravitational wave detectors: an update 8 Universality and scaling in gravitational collapse 9 Gravitational Wave memories upgraded 11 Conference report: quantum aspects of black holes 13 Conference report: knots and quantum gravity 14 Conference report: deterministic chaos in GR 17 |
1102.3022 | Ian G. Moss | Ian G Moss | Black holes with current loops revisited | 10 pages, 5 figures. v2: 3 new references, revisions in Sect. 3 | null | 10.1103/PhysRevD.83.124046 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The electromagnetic field around a Kerr black hole inside a current loop is
sometimes used as the basis of a toy model for discussing the properties of
particle orbits near astrophysical black holes. The motivation for the present
paper is to correct the published solution to Maxwell's equations with a
charged current loop. Dipole approximations and closed-form expressions in the
extreme Kerr limit are also presented. Using the corrected solution, it turns
out that imposing a vanishing electromotive force produces a loop with a
potential which is finite everywhere outside the black hole. Ring solutions can
be combined into solutions with multiple rings or current discs.
| [
{
"created": "Tue, 15 Feb 2011 10:13:45 GMT",
"version": "v1"
},
{
"created": "Wed, 8 Jun 2011 15:17:44 GMT",
"version": "v2"
}
] | 2013-05-29 | [
[
"Moss",
"Ian G",
""
]
] | The electromagnetic field around a Kerr black hole inside a current loop is sometimes used as the basis of a toy model for discussing the properties of particle orbits near astrophysical black holes. The motivation for the present paper is to correct the published solution to Maxwell's equations with a charged current loop. Dipole approximations and closed-form expressions in the extreme Kerr limit are also presented. Using the corrected solution, it turns out that imposing a vanishing electromotive force produces a loop with a potential which is finite everywhere outside the black hole. Ring solutions can be combined into solutions with multiple rings or current discs. |
2303.03924 | Andreu Maso-Ferrando | Renan B. Magalh\~aes, Andreu Mas\'o-Ferrando, Gonzalo J. Olmo, Lu\'is
C. B. Crispino | Asymmetric wormholes in Palatini $f(\mathcal{R})$ gravity: Energy
conditions, absorption and quasibound states | 18 pages, 13 figures, revtex4-2 style | null | 10.1103/PhysRevD.108.024063 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We investigate the absorption properties of reflection-asymmetric wormholes
constructed via the thin-shell formalism in Palatini $f({\cal R})$ gravity.
Such wormholes come from the matching of two Reissner-Nordstr\"om spacetimes at
a time-like hypersurface (shell), which, according to the junction conditions
in Palatini $f({\cal R})$ gravity, can have positive or negative energy
density. Using numerical methods we investigate several configurations that
satisfy the junction conditions, and analyze how the parameters of the system
affect the absorption spectra. We confirm that the absorption cross section of
wormholes at low frequencies significantly departs from that of black holes,
and observe that in configurations made out of two naked singularities, the
absorption spectra exhibit new features due to the effective light ring
associated to the wormhole throat. The possibility of observing the presence of
resonances at high frequencies is also discussed.
| [
{
"created": "Tue, 7 Mar 2023 14:31:24 GMT",
"version": "v1"
},
{
"created": "Tue, 26 Sep 2023 13:22:48 GMT",
"version": "v2"
}
] | 2024-05-30 | [
[
"Magalhães",
"Renan B.",
""
],
[
"Masó-Ferrando",
"Andreu",
""
],
[
"Olmo",
"Gonzalo J.",
""
],
[
"Crispino",
"Luís C. B.",
""
]
] | We investigate the absorption properties of reflection-asymmetric wormholes constructed via the thin-shell formalism in Palatini $f({\cal R})$ gravity. Such wormholes come from the matching of two Reissner-Nordstr\"om spacetimes at a time-like hypersurface (shell), which, according to the junction conditions in Palatini $f({\cal R})$ gravity, can have positive or negative energy density. Using numerical methods we investigate several configurations that satisfy the junction conditions, and analyze how the parameters of the system affect the absorption spectra. We confirm that the absorption cross section of wormholes at low frequencies significantly departs from that of black holes, and observe that in configurations made out of two naked singularities, the absorption spectra exhibit new features due to the effective light ring associated to the wormhole throat. The possibility of observing the presence of resonances at high frequencies is also discussed. |
1105.5842 | Hideyuki Tagoshi | Sanjeev Dhurandhar, Hideyuki Tagoshi, Yuta Okada, Nobuyuki Kanda,
Hirotaka Takahashi | The cross-correlation search for a hot spot of gravitational waves | 7 pages, 2 figures | null | 10.1103/PhysRevD.84.083007 | OU-TAP 314 | gr-qc astro-ph.HE astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The cross-correlation search has been previously applied to map the
gravitational wave (GW) stochastic background in the sky and also to target GW
from rotating neutron stars/pulsars. Here we investigate how the
cross-correlation method can be used to target a small region in the sky
spanning at most a few pixels, where a pixel in the sky is determined by the
diffraction limit which depends on the (i) baseline joining a pair of detectors
and (ii) detector bandwidth. Here as one of the promising targets, we consider
the Virgo cluster - a "hot spot" spanning few pixels - which could contain, as
estimates suggest $\sim 10^{11}$ neutron stars, of which a small fraction would
continuously emit GW in the bandwidth of the detectors. For the detector
baselines, we consider advanced detector pairs among LCGT, LIGO, Virgo, ET etc.
Our results show that sufficient signal to noise can be accumulated with
integration times of the order of a year. The results improve for the
multibaseline search. This analysis could as well be applied to other likely
hot spots in the sky and other possible pairs of detectors.
| [
{
"created": "Mon, 30 May 2011 00:33:20 GMT",
"version": "v1"
}
] | 2013-05-29 | [
[
"Dhurandhar",
"Sanjeev",
""
],
[
"Tagoshi",
"Hideyuki",
""
],
[
"Okada",
"Yuta",
""
],
[
"Kanda",
"Nobuyuki",
""
],
[
"Takahashi",
"Hirotaka",
""
]
] | The cross-correlation search has been previously applied to map the gravitational wave (GW) stochastic background in the sky and also to target GW from rotating neutron stars/pulsars. Here we investigate how the cross-correlation method can be used to target a small region in the sky spanning at most a few pixels, where a pixel in the sky is determined by the diffraction limit which depends on the (i) baseline joining a pair of detectors and (ii) detector bandwidth. Here as one of the promising targets, we consider the Virgo cluster - a "hot spot" spanning few pixels - which could contain, as estimates suggest $\sim 10^{11}$ neutron stars, of which a small fraction would continuously emit GW in the bandwidth of the detectors. For the detector baselines, we consider advanced detector pairs among LCGT, LIGO, Virgo, ET etc. Our results show that sufficient signal to noise can be accumulated with integration times of the order of a year. The results improve for the multibaseline search. This analysis could as well be applied to other likely hot spots in the sky and other possible pairs of detectors. |
1706.03037 | Samuel Colin | Samuel Colin and Nelson Pinto-Neto | Quantum matter bounce with a dark energy expanding phase | 15 pages, 17 figures. Title changed, introduction, conclusion and
bibliography expanded to answer the questions of a referee. To be published
in Physical Review D | Phys. Rev. D 96, 063502 (2017) | 10.1103/PhysRevD.96.063502 | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Analyzing quantum cosmological scenarios containing one scalar field with
exponential potential, we have obtained a universe model which realizes a
classical dust contraction from very large scales, the initial repeller of the
model, and moves to a stiff matter contraction near the singularity, which is
avoided due to a quantum bounce. The universe is then launched in a stiff
matter expanding phase, which then moves to a dark energy era, finally
returning to the dust expanding phase, the final attractor of the model. Hence
one has obtained a nonsingular cosmological model where a single scalar field
can describe both the matter contracting phase of a bouncing model, necessary
to give an almost scale invariant spectrum of scalar cosmological
perturbations, and a transient expanding dark energy phase. As the universe is
necessarily dust dominated in the far past, usual adiabatic vacuum initial
conditions can be easily imposed in this era, avoiding the usual issues
appearing when dark energy is considered in bouncing models.
| [
{
"created": "Fri, 9 Jun 2017 16:51:53 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Aug 2017 08:03:34 GMT",
"version": "v2"
}
] | 2017-09-13 | [
[
"Colin",
"Samuel",
""
],
[
"Pinto-Neto",
"Nelson",
""
]
] | Analyzing quantum cosmological scenarios containing one scalar field with exponential potential, we have obtained a universe model which realizes a classical dust contraction from very large scales, the initial repeller of the model, and moves to a stiff matter contraction near the singularity, which is avoided due to a quantum bounce. The universe is then launched in a stiff matter expanding phase, which then moves to a dark energy era, finally returning to the dust expanding phase, the final attractor of the model. Hence one has obtained a nonsingular cosmological model where a single scalar field can describe both the matter contracting phase of a bouncing model, necessary to give an almost scale invariant spectrum of scalar cosmological perturbations, and a transient expanding dark energy phase. As the universe is necessarily dust dominated in the far past, usual adiabatic vacuum initial conditions can be easily imposed in this era, avoiding the usual issues appearing when dark energy is considered in bouncing models. |
gr-qc/0204083 | Emil Mottola | Paul R. Anderson, Carmen Molina-Paris, and Emil Mottola | Linear Response and the Validity of the Semi-Classical Approximation in
Gravity | 8 pages, LaTeX | null | null | LA-UR-02-2072 | gr-qc | null | We propose a quantitative test for the validity of the semi-classical
approximation in gravity, namely that the solutions to the semi-classical
equations should be stable to linearized perturbations, in the sense that no
gauge invariant perturbation should become unbounded in time. We show that a
self-consistent linear response analysis of these perturbations based upon an
invariant effective action principle involves metric fluctuations about the
mean semi-classical geometry and brings in the two-point correlation function
of the quantum energy-momentum tensor in a natural way. The properties of this
correlation function are discussed and it is shown on general grounds that it
contains no state-dependent divergences and requires no new renormalization
counterterms beyond those required in the leading order semi-classical
approximation.
| [
{
"created": "Sat, 27 Apr 2002 00:40:07 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Anderson",
"Paul R.",
""
],
[
"Molina-Paris",
"Carmen",
""
],
[
"Mottola",
"Emil",
""
]
] | We propose a quantitative test for the validity of the semi-classical approximation in gravity, namely that the solutions to the semi-classical equations should be stable to linearized perturbations, in the sense that no gauge invariant perturbation should become unbounded in time. We show that a self-consistent linear response analysis of these perturbations based upon an invariant effective action principle involves metric fluctuations about the mean semi-classical geometry and brings in the two-point correlation function of the quantum energy-momentum tensor in a natural way. The properties of this correlation function are discussed and it is shown on general grounds that it contains no state-dependent divergences and requires no new renormalization counterterms beyond those required in the leading order semi-classical approximation. |
gr-qc/0310028 | Yousuke Itoh | Yousuke Itoh, Toshifumi Futamase | New derivation of a third post-Newtonian equation of motion for
relativistic compact binaries without ambiguity | 6 pages, No figure, Revised version,clarity improved, accepted for
publication in Phys. Rev. D.(R) | Phys.Rev. D68 (2003) 121501 | 10.1103/PhysRevD.68.121501 | null | gr-qc | null | A third post-Newtonian (3 PN) equation of motion for an inspiralling binary
consisting of two spherical compact stars with strong internal gravity is
derived under harmonic coordinate condition using the strong field point
particle limit. The equation of motion is complete in a sense that it is
Lorentz invariant in the post-Newtonian perturbative sense, admits conserved
energy of the orbital motion, and is unambiguous, that is, with no undetermined
coefficient. In this paper, we show explicit expressions of the 3 PN equation
of motion and an energy of the binary orbital motion in case of the circular
orbit (neglecting the 2.5 PN radiation reaction effect) and in the center of
the mass frame. It is argued that the 3 PN equation of motion we obtained is
physically unambiguous. Full details will be reported elsewhere.
| [
{
"created": "Mon, 6 Oct 2003 13:29:28 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Jan 2004 10:29:14 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Itoh",
"Yousuke",
""
],
[
"Futamase",
"Toshifumi",
""
]
] | A third post-Newtonian (3 PN) equation of motion for an inspiralling binary consisting of two spherical compact stars with strong internal gravity is derived under harmonic coordinate condition using the strong field point particle limit. The equation of motion is complete in a sense that it is Lorentz invariant in the post-Newtonian perturbative sense, admits conserved energy of the orbital motion, and is unambiguous, that is, with no undetermined coefficient. In this paper, we show explicit expressions of the 3 PN equation of motion and an energy of the binary orbital motion in case of the circular orbit (neglecting the 2.5 PN radiation reaction effect) and in the center of the mass frame. It is argued that the 3 PN equation of motion we obtained is physically unambiguous. Full details will be reported elsewhere. |
2101.09431 | Lijing Shao | Rui Xu, Yong Gao, Lijing Shao | Signature of Lorentz Violation in Continuous Gravitational-Wave Spectra
of Ellipsoidal Neutron Stars | 8 pages, 4 figures; Invited research article to special issue
"Lorentz Violation in Astroparticles and Gravitational Waves", in press | Galaxies 2021, 9:12 | 10.3390/galaxies9010012 | null | gr-qc astro-ph.HE hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study effects of Lorentz-invariance violation on the rotation of neutron
stars (NSs) in the minimal gravitational Standard-Model Extension framework,
and calculate the quadrupole radiation generated by them. Aiming at testing
Lorentz invariance with observations of continuous gravitational waves (GWs)
from rotating NSs in the future, we compare the GW spectra of a rotating
ellipsoidal NS under Lorentz-violating gravity with those of a
Lorentz-invariant one. The former are found to possess frequency components
higher than the second harmonic, which does not happen for the latter,
indicating those higher frequency components to be potential signatures of
Lorentz violation in continuous GW spectra of rotating NSs.
| [
{
"created": "Sat, 23 Jan 2021 06:31:41 GMT",
"version": "v1"
}
] | 2021-02-01 | [
[
"Xu",
"Rui",
""
],
[
"Gao",
"Yong",
""
],
[
"Shao",
"Lijing",
""
]
] | We study effects of Lorentz-invariance violation on the rotation of neutron stars (NSs) in the minimal gravitational Standard-Model Extension framework, and calculate the quadrupole radiation generated by them. Aiming at testing Lorentz invariance with observations of continuous gravitational waves (GWs) from rotating NSs in the future, we compare the GW spectra of a rotating ellipsoidal NS under Lorentz-violating gravity with those of a Lorentz-invariant one. The former are found to possess frequency components higher than the second harmonic, which does not happen for the latter, indicating those higher frequency components to be potential signatures of Lorentz violation in continuous GW spectra of rotating NSs. |
1501.01985 | Constantinos Skordis | Ana Avilez-Lopez, Antonio Padilla, Paul M. Saffin and Constantinos
Skordis | The Parametrized Post-Newtonian-Vainshteinian Formalism | 26 pages, 1 figure. Few clarifications made according to referee's
comments. No change to the results. Matches published version | JCAP 06 (2015) 044 | 10.1088/1475-7516/2015/06/044 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Light degrees of freedom that modify gravity on cosmological scales must be
"screened" on solar system scales in order to be compatible with data. The
Vainshtein mechanism achieves this through a breakdown of classical
perturbation theory, as large interactions involving new degrees of freedom
become important below the so-called Vainshtein radius. We begin to develop an
extension of the Parameterized Post-Newtonian (PPN) formalism that is able to
handle Vainshteinian corrections. We argue that theories with a unique
Vainshtein scale must be expanded using two small parameters. In this
Parameterized Post-Newtonian-Vainshteinian (PPNV) expansion, the primary
expansion parameter that controls the PPN order is, as usual, the velocity $v$.
The secondary expansion parameter, $\alpha$, controls the strength of the
Vainshteinian correction and is a theory-specific combination of the
Schwarzschild radius and the Vainshtein radius of the source that is
independent of its mass. We present the general framework and apply it to Cubic
Galileon theory both inside and outside the Vainshtein radius. The PPNV
framework can be used to determine the compatibility of such theories with
solar system and other strong-field data.
| [
{
"created": "Thu, 8 Jan 2015 21:07:01 GMT",
"version": "v1"
},
{
"created": "Fri, 26 Jun 2015 06:13:15 GMT",
"version": "v2"
}
] | 2015-06-29 | [
[
"Avilez-Lopez",
"Ana",
""
],
[
"Padilla",
"Antonio",
""
],
[
"Saffin",
"Paul M.",
""
],
[
"Skordis",
"Constantinos",
""
]
] | Light degrees of freedom that modify gravity on cosmological scales must be "screened" on solar system scales in order to be compatible with data. The Vainshtein mechanism achieves this through a breakdown of classical perturbation theory, as large interactions involving new degrees of freedom become important below the so-called Vainshtein radius. We begin to develop an extension of the Parameterized Post-Newtonian (PPN) formalism that is able to handle Vainshteinian corrections. We argue that theories with a unique Vainshtein scale must be expanded using two small parameters. In this Parameterized Post-Newtonian-Vainshteinian (PPNV) expansion, the primary expansion parameter that controls the PPN order is, as usual, the velocity $v$. The secondary expansion parameter, $\alpha$, controls the strength of the Vainshteinian correction and is a theory-specific combination of the Schwarzschild radius and the Vainshtein radius of the source that is independent of its mass. We present the general framework and apply it to Cubic Galileon theory both inside and outside the Vainshtein radius. The PPNV framework can be used to determine the compatibility of such theories with solar system and other strong-field data. |
0709.1238 | Geusa Marques AMarques | Geusa de A. Marques and V. B. Bezerra | Corrections to the fine structure constant in higher dimensional global
monopole spacetime | No figures, 3 pages | null | null | null | gr-qc hep-th | null | In this paper we use the Generalized Uncertainty Principle in order to obtain
the corrections to the fine structure constant in (D+1)-dimensional global
monopole spacetime. The result is particularized to D-dimensional spacetime. We
also discuss the particular case D=3 corresponding to the (3+1)-dimensional
global monopole spacetime.
| [
{
"created": "Sun, 9 Sep 2007 01:10:25 GMT",
"version": "v1"
},
{
"created": "Wed, 12 Sep 2007 14:14:06 GMT",
"version": "v2"
},
{
"created": "Thu, 3 Jan 2008 20:05:16 GMT",
"version": "v3"
},
{
"created": "Fri, 4 Jan 2008 13:21:47 GMT",
"version": "v4"
}
] | 2011-11-10 | [
[
"Marques",
"Geusa de A.",
""
],
[
"Bezerra",
"V. B.",
""
]
] | In this paper we use the Generalized Uncertainty Principle in order to obtain the corrections to the fine structure constant in (D+1)-dimensional global monopole spacetime. The result is particularized to D-dimensional spacetime. We also discuss the particular case D=3 corresponding to the (3+1)-dimensional global monopole spacetime. |
2306.13845 | Christoph Adami | Christoph Adami (Michigan State University) | Stimulated Emission of Radiation and the Black Hole Information Problem | 40 pages, 21 figures | null | null | null | gr-qc quant-ph | http://creativecommons.org/licenses/by/4.0/ | The quantum theory of black holes has opened up a window to study the
intersection of general relativity and quantum field theory, but perceived
paradoxes concerning the fate of classical information directed at a black hole
horizon, as well as concerning the unitarity of the evaporation process, have
led researchers to question the very foundations of physics. In this
pedagogical review I clarify the ramifications of the fact that black holes not
only emit radiation spontaneously, but also respond to infalling matter and
radiation by emitting approximate clones of those fields in a stimulated
manner. I review early purely statistical arguments based on Einstein's
treatment of black bodies, and then show that the Holevo capacity of the black
hole (the capacity to transmit classical information through a quantum channel)
is always positive. I then show how stimulated emission turns the black hole
into an almost optimal quantum cloning machine, and furthermore discuss the
capacity of black holes to transmit quantum information. Taking advantage of an
analogy between black hole physics and non-linear optics I show that a
calculation of the evolution of a black hole over time, using a discretization
of the black hole $S$-matrix path integral, yields well-behaved Page curves
suggesting that black hole evaporation is unitary. Finally, I speculate about
possible observable consequences of stimulated emission of radiation in black
holes.
| [
{
"created": "Sat, 24 Jun 2023 03:05:48 GMT",
"version": "v1"
}
] | 2023-06-27 | [
[
"Adami",
"Christoph",
"",
"Michigan State University"
]
] | The quantum theory of black holes has opened up a window to study the intersection of general relativity and quantum field theory, but perceived paradoxes concerning the fate of classical information directed at a black hole horizon, as well as concerning the unitarity of the evaporation process, have led researchers to question the very foundations of physics. In this pedagogical review I clarify the ramifications of the fact that black holes not only emit radiation spontaneously, but also respond to infalling matter and radiation by emitting approximate clones of those fields in a stimulated manner. I review early purely statistical arguments based on Einstein's treatment of black bodies, and then show that the Holevo capacity of the black hole (the capacity to transmit classical information through a quantum channel) is always positive. I then show how stimulated emission turns the black hole into an almost optimal quantum cloning machine, and furthermore discuss the capacity of black holes to transmit quantum information. Taking advantage of an analogy between black hole physics and non-linear optics I show that a calculation of the evolution of a black hole over time, using a discretization of the black hole $S$-matrix path integral, yields well-behaved Page curves suggesting that black hole evaporation is unitary. Finally, I speculate about possible observable consequences of stimulated emission of radiation in black holes. |
1905.09973 | Jing Ren | Jing Ren | Anatomy of a thermal black hole mimicker | 25 pages, 3 figures, 1 table; minor corrections, matches published
version | Phys. Rev. D 100, 124012 (2019) | 10.1103/PhysRevD.100.124012 | null | gr-qc astro-ph.HE hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We are entering a new era to test the strong gravity regime around
astrophysical black holes. The possibility that they are actually horizonless
ultracompact objects and then free from the information loss paradox can be
examined more closely with observational data. In this paper, we systematically
develop a thermal gas model of the 2-2-hole in quadratic gravity, as one step
further to look for more tractable models of black hole mimickers. Concrete
predictions for departures from black holes are made all the way down to the
high curvature interior. The simple form of matter further enables an explicit
study of the relation between geometry and thermodynamics. Within this unified
framework, we identify notably different behaviors at two limits. On one side
is the astrophysically large 2-2-hole, as characterized by a minuscule
deviation outside the would-be horizon and a highly squeezed interior along the
radial direction. Anomalous features of black hole thermodynamics emerge from
the ordinary gas. On the other side is the minimal 2-2-hole with an isotropic
and shrinking interior, which behaves more like a normal thermodynamic system.
This brings a new perspective to the related theoretical questions as well as
phenomenological implications.
| [
{
"created": "Thu, 23 May 2019 23:58:33 GMT",
"version": "v1"
},
{
"created": "Sat, 7 Dec 2019 04:41:31 GMT",
"version": "v2"
}
] | 2019-12-11 | [
[
"Ren",
"Jing",
""
]
] | We are entering a new era to test the strong gravity regime around astrophysical black holes. The possibility that they are actually horizonless ultracompact objects and then free from the information loss paradox can be examined more closely with observational data. In this paper, we systematically develop a thermal gas model of the 2-2-hole in quadratic gravity, as one step further to look for more tractable models of black hole mimickers. Concrete predictions for departures from black holes are made all the way down to the high curvature interior. The simple form of matter further enables an explicit study of the relation between geometry and thermodynamics. Within this unified framework, we identify notably different behaviors at two limits. On one side is the astrophysically large 2-2-hole, as characterized by a minuscule deviation outside the would-be horizon and a highly squeezed interior along the radial direction. Anomalous features of black hole thermodynamics emerge from the ordinary gas. On the other side is the minimal 2-2-hole with an isotropic and shrinking interior, which behaves more like a normal thermodynamic system. This brings a new perspective to the related theoretical questions as well as phenomenological implications. |
gr-qc/0211088 | Farid Ya. Khalili | F.Ya.Khalili | Quantum speedmeter and laser interferometric gravitational-wave antennae | 20 pages, 6 figures drawn in TeX | null | null | null | gr-qc | null | A new topology of laser interferometric gravitational-wave antenna is
considered. It is based on two schemes: {\em quantum speedmeter} and {\em
zero-area Sagnac interferometer} and allows to obtain sensitivity better than
the Standard Quantum Limit in wide band without any large-scale modifications
of the standard topology of the laser interferometric antennae.
| [
{
"created": "Tue, 26 Nov 2002 19:39:52 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Khalili",
"F. Ya.",
""
]
] | A new topology of laser interferometric gravitational-wave antenna is considered. It is based on two schemes: {\em quantum speedmeter} and {\em zero-area Sagnac interferometer} and allows to obtain sensitivity better than the Standard Quantum Limit in wide band without any large-scale modifications of the standard topology of the laser interferometric antennae. |
1806.08347 | Luc Blanchet | Luc Blanchet and Athanassios S. Fokas | Equations of motion of self-gravitating $N$-body systems in the first
post-Minkowskian approximation | 30 pages, 2 figures | Phys. Rev. D 98, 084005 (2018) | 10.1103/PhysRevD.98.084005 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We revisit the problem of the equations of motion of a system of $N$
self-interacting massive particles (without spins) in the first
post-Minkowskian (1PM) approximation of general relativity. We write the
equations of motion, gravitational field and associated conserved integrals of
the motion in a form suitable for comparison with recently published
post-Newtonian (PN) results at the 4PN order. We show that the Lagrangian
associated with the equations of motion in harmonic coordinates is a
generalized one, and compute all the terms linear in $G$ up to 5PN order. We
discuss the Hamiltonian in the frame of the center of mass and exhibit a
canonical transformation connecting it to previous results directly obtained
with the Hamiltonian formalism of general relativity. Finally we recover the
known result for the gravitational scattering angle of two particles at the 1PM
order.
| [
{
"created": "Thu, 21 Jun 2018 17:53:36 GMT",
"version": "v1"
}
] | 2018-10-17 | [
[
"Blanchet",
"Luc",
""
],
[
"Fokas",
"Athanassios S.",
""
]
] | We revisit the problem of the equations of motion of a system of $N$ self-interacting massive particles (without spins) in the first post-Minkowskian (1PM) approximation of general relativity. We write the equations of motion, gravitational field and associated conserved integrals of the motion in a form suitable for comparison with recently published post-Newtonian (PN) results at the 4PN order. We show that the Lagrangian associated with the equations of motion in harmonic coordinates is a generalized one, and compute all the terms linear in $G$ up to 5PN order. We discuss the Hamiltonian in the frame of the center of mass and exhibit a canonical transformation connecting it to previous results directly obtained with the Hamiltonian formalism of general relativity. Finally we recover the known result for the gravitational scattering angle of two particles at the 1PM order. |
2312.15183 | Albert Munyeshyaka Mr | Albert Munyeshyaka, Joseph Ntahompagaze, Tom Mutabazi and Manasse.R
Mbonye | On covariant perturbations with scalar field in modified Gauss-Bonnet
gravity | 36 pages, 14 figures. This Article was accepted for publication in
European Physical Journal C (EPJC) on December 22, 2023 | null | null | null | gr-qc | http://creativecommons.org/licenses/by-nc-sa/4.0/ | We investigate cosmological perturbations of f(G) gravity in the presence of
a scalar field. Using the 1 + 3 covariant formalism, we present the energy
overdensity perturbation equations responsible for large scale structure
formation. After applying harmonic decomposition method together with the
redshift transformation technique, we obtain the fully perturbed equations in
redshift space. The equations are solved to study the growth of matter
overdensities contrast with redshift. For both short- and long-wavelength
modes, we obtain numerical results for particular functional form f(G) models
and scalar field. We find that, for this choice the energy overdensity
perturbations decay with increase in redshift. However, for both short- and
long- wavelength modes, the perturbations which include amplitude effects due
to the f(G) models with a scalar field do differ remarkably from those in
Lambda CDM. The results reduce to GR results in the limit of f(G) tends to G
and in the absence of scalar field.
| [
{
"created": "Sat, 23 Dec 2023 07:43:24 GMT",
"version": "v1"
}
] | 2023-12-27 | [
[
"Munyeshyaka",
"Albert",
""
],
[
"Ntahompagaze",
"Joseph",
""
],
[
"Mutabazi",
"Tom",
""
],
[
"Mbonye",
"Manasse. R",
""
]
] | We investigate cosmological perturbations of f(G) gravity in the presence of a scalar field. Using the 1 + 3 covariant formalism, we present the energy overdensity perturbation equations responsible for large scale structure formation. After applying harmonic decomposition method together with the redshift transformation technique, we obtain the fully perturbed equations in redshift space. The equations are solved to study the growth of matter overdensities contrast with redshift. For both short- and long-wavelength modes, we obtain numerical results for particular functional form f(G) models and scalar field. We find that, for this choice the energy overdensity perturbations decay with increase in redshift. However, for both short- and long- wavelength modes, the perturbations which include amplitude effects due to the f(G) models with a scalar field do differ remarkably from those in Lambda CDM. The results reduce to GR results in the limit of f(G) tends to G and in the absence of scalar field. |
1109.5224 | Richard O'Shaughnessy | R. O'Shaughnessy (1), B. Vaishnav (2), J. Healy (3), Z. Meeks (3), D.
Shoemaker (3) ((1) University of Wisconsin, Milwaukee, (2) Georgia Southern
University, (3) Center for Relativistic Astrophysics, Georgia Tech) | Efficient asymptotic frame selection for binary black hole spacetimes
using asymptotic radiation | Submitted to PRD | null | 10.1103/PhysRevD.84.124002 | LIGO DCC P1100113 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Previous studies have demonstrated that gravitational radiation reliably
encodes information about the natural emission direction of the source (e.g.,
the orbital plane). In this paper, we demonstrate that these orientations can
be efficiently estimated by the principal axes of <L_a L_b>, an average of the
action of rotation group generators on the Weyl tensor at asymptotic infinity.
Evaluating this average at each time provides the instantaneous emission
direction. Further averaging across the entire signal yields an average
orientation, closely connected to the angular components of the Fisher matrix.
The latter direction is well-suited to data analysis and parameter estimation
when the instantaneous emission direction evolves significantly. Finally, in
the time domain, the average <L_a L_b> provides fast, invariant diagnostics of
waveform quality.
| [
{
"created": "Sat, 24 Sep 2011 02:37:16 GMT",
"version": "v1"
}
] | 2015-05-30 | [
[
"O'Shaughnessy",
"R.",
""
],
[
"Vaishnav",
"B.",
""
],
[
"Healy",
"J.",
""
],
[
"Meeks",
"Z.",
""
],
[
"Shoemaker",
"D.",
""
]
] | Previous studies have demonstrated that gravitational radiation reliably encodes information about the natural emission direction of the source (e.g., the orbital plane). In this paper, we demonstrate that these orientations can be efficiently estimated by the principal axes of <L_a L_b>, an average of the action of rotation group generators on the Weyl tensor at asymptotic infinity. Evaluating this average at each time provides the instantaneous emission direction. Further averaging across the entire signal yields an average orientation, closely connected to the angular components of the Fisher matrix. The latter direction is well-suited to data analysis and parameter estimation when the instantaneous emission direction evolves significantly. Finally, in the time domain, the average <L_a L_b> provides fast, invariant diagnostics of waveform quality. |
gr-qc/0412009 | Warren G. Anderson | Warren G. Anderson, Eanna E. Flanagan, Adrian C. Ottewill | Quasi-local contribution to the gravitational self-force | 22 pages, revtex4, submitted to PRD | Phys.Rev. D71 (2005) 024036 | 10.1103/PhysRevD.71.024036 | null | gr-qc | null | The gravitational self-force on a point particle moving in a vacuum
background spacetime can be expressed as an integral over the past worldline of
the particle, the so-called tail term. In this paper, we consider that piece of
the self-force obtained by integrating over a portion of the past worldline
that extends a proper time ${\Delta}{\tau}$ into the past, provided that
${\Delta}{\tau}$ does not extend beyond the normal neighborhood of the
particle. We express this ``quasi-local'' piece as a power series in the proper
time interval ${\Delta}{\tau}$. We argue from symmetries and dimensional
considerations that the $O({\Delta}{\tau}^0)$ and $O({\Delta}{\tau})$ terms in
this power series must vanish, and compute the first two non-vanishing terms
which occur at $O({\Delta}{\tau}^2)$ and $O({\Delta}{\tau}^3)$. The
coefficients in the expansion depend only on the particle's four velocity and
on the Weyl tensor and its derivatives at the particle's location. The result
may be useful as a foundation for a practical computational method for
gravitational self-forces in the Kerr spacetime, in which the portion of the
tail integral in the distant past is computed numerically from a mode sum
decomposition.
| [
{
"created": "Thu, 2 Dec 2004 21:16:22 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Anderson",
"Warren G.",
""
],
[
"Flanagan",
"Eanna E.",
""
],
[
"Ottewill",
"Adrian C.",
""
]
] | The gravitational self-force on a point particle moving in a vacuum background spacetime can be expressed as an integral over the past worldline of the particle, the so-called tail term. In this paper, we consider that piece of the self-force obtained by integrating over a portion of the past worldline that extends a proper time ${\Delta}{\tau}$ into the past, provided that ${\Delta}{\tau}$ does not extend beyond the normal neighborhood of the particle. We express this ``quasi-local'' piece as a power series in the proper time interval ${\Delta}{\tau}$. We argue from symmetries and dimensional considerations that the $O({\Delta}{\tau}^0)$ and $O({\Delta}{\tau})$ terms in this power series must vanish, and compute the first two non-vanishing terms which occur at $O({\Delta}{\tau}^2)$ and $O({\Delta}{\tau}^3)$. The coefficients in the expansion depend only on the particle's four velocity and on the Weyl tensor and its derivatives at the particle's location. The result may be useful as a foundation for a practical computational method for gravitational self-forces in the Kerr spacetime, in which the portion of the tail integral in the distant past is computed numerically from a mode sum decomposition. |
1907.12517 | Hao Wei | Zhong-Xi Yu, Shou-Long Li, Hao Wei | Lemaitre-Tolman-Bondi Static Universe in Rastall-like Gravity | 14 pages, revtex4; v2: discussions added, Nucl. Phys. B in press; v3:
published version | Nucl. Phys. B 960 (2020) 115179 | 10.1016/j.nuclphysb.2020.115179 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we try to obtain a stable Lemaitre-Tolman-Bondi (LTB) static
universe, which is spherically symmetric and radially inhomogeneous. However,
this is not an easy task, and fails in general relativity (GR) and various
modified gravity theories, because the corresponding LTB static universes must
reduce to the Friedmann-Robertson-Walker (FRW) static universes. We find a way
out in a new type of modified gravity theory, in which the conservation of
energy and momentum is broken. In this work, we have proposed a novel
modification to the original Rastall gravity. In some sense, our Rastall-like
gravity is essentially different from GR and the original Rastall gravity. In
this Rastall-like gravity, LTB static solutions have been found. The stability
of LTB static universe against both the homogeneous and the inhomogeneous
scalar perturbations is also discussed in details. We show that a LTB static
universe can be stable in this Rastall-like gravity.
| [
{
"created": "Mon, 29 Jul 2019 16:45:00 GMT",
"version": "v1"
},
{
"created": "Sun, 6 Sep 2020 07:36:00 GMT",
"version": "v2"
},
{
"created": "Wed, 28 Oct 2020 04:00:00 GMT",
"version": "v3"
}
] | 2020-10-29 | [
[
"Yu",
"Zhong-Xi",
""
],
[
"Li",
"Shou-Long",
""
],
[
"Wei",
"Hao",
""
]
] | In this work, we try to obtain a stable Lemaitre-Tolman-Bondi (LTB) static universe, which is spherically symmetric and radially inhomogeneous. However, this is not an easy task, and fails in general relativity (GR) and various modified gravity theories, because the corresponding LTB static universes must reduce to the Friedmann-Robertson-Walker (FRW) static universes. We find a way out in a new type of modified gravity theory, in which the conservation of energy and momentum is broken. In this work, we have proposed a novel modification to the original Rastall gravity. In some sense, our Rastall-like gravity is essentially different from GR and the original Rastall gravity. In this Rastall-like gravity, LTB static solutions have been found. The stability of LTB static universe against both the homogeneous and the inhomogeneous scalar perturbations is also discussed in details. We show that a LTB static universe can be stable in this Rastall-like gravity. |
2012.04381 | Banafsheh Beheshtipour | Banafsheh Beheshtipour, Maria Alessandra Papa | Deep learning for clustering of continuous gravitational wave candidates
II: identification of low-SNR candidates | null | Phys. Rev. D 103, 064027 (2021) | 10.1103/PhysRevD.103.064027 | null | gr-qc astro-ph.HE cs.LG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Broad searches for continuous gravitational wave signals rely on hierarchies
of follow-up stages for candidates above a given significance threshold. An
important step to simplify these follow-ups and reduce the computational cost
is to bundle together in a single follow-up nearby candidates. This step is
called clustering and we investigate carrying it out with a deep learning
network. In our first paper [1], we implemented a deep learning clustering
network capable of correctly identifying clusters due to large signals. In this
paper, a network is implemented that can detect clusters due to much fainter
signals. These two networks are complementary and we show that a cascade of the
two networks achieves an excellent detection efficiency across a wide range of
signal strengths, with a false alarm rate comparable/lower than that of methods
currently in use.
| [
{
"created": "Tue, 8 Dec 2020 11:54:08 GMT",
"version": "v1"
},
{
"created": "Fri, 12 Feb 2021 15:39:38 GMT",
"version": "v2"
}
] | 2021-03-24 | [
[
"Beheshtipour",
"Banafsheh",
""
],
[
"Papa",
"Maria Alessandra",
""
]
] | Broad searches for continuous gravitational wave signals rely on hierarchies of follow-up stages for candidates above a given significance threshold. An important step to simplify these follow-ups and reduce the computational cost is to bundle together in a single follow-up nearby candidates. This step is called clustering and we investigate carrying it out with a deep learning network. In our first paper [1], we implemented a deep learning clustering network capable of correctly identifying clusters due to large signals. In this paper, a network is implemented that can detect clusters due to much fainter signals. These two networks are complementary and we show that a cascade of the two networks achieves an excellent detection efficiency across a wide range of signal strengths, with a false alarm rate comparable/lower than that of methods currently in use. |
gr-qc/0304096 | Pia Astone | Pia Astone, Giulio D'Agostini, Sabrina D'Antonio | Bayesian model comparison applied to the Explorer-Nautilus 2001
coincidence data | 16 pages, 4 figures. Presented at the GWDAW2002 conference, held in
Kyoto on Dec.,2002. This version includes comments by the referees of CQG,
which has accepted the paper for pubblication in the special issue of the
conference. In particular, note that in Eq. 12 there was a typeset error. As
suggested by one of the referees, a uniform prior in Log(alpha) has also been
considered | Class.Quant.Grav. 20 (2003) S769-S784 | 10.1088/0264-9381/20/17/320 | null | gr-qc astro-ph physics.data-an | null | Bayesian reasoning is applied to the data by the ROG Collaboration, in which
gravitational wave (g.w.) signals are searched for in a coincidence experiment
between Explorer and Nautilus. The use of Bayesian reasoning allows, under well
defined hypotheses, even tiny pieces of evidence in favor of each model to be
extracted from the data. The combination of the data of several experiments can
therefore be performed in an optimal and efficient way. Some models for
Galactic sources are considered and, within each model, the experimental result
is summarized with the likelihood rescaled to the insensitivity limit value
(``${\cal R}$ function''). The model comparison result is given in in terms of
Bayes factors, which quantify how the ratio of beliefs about two alternative
models are modified by the experimental observation
| [
{
"created": "Thu, 24 Apr 2003 21:39:47 GMT",
"version": "v1"
},
{
"created": "Sun, 27 Apr 2003 08:47:29 GMT",
"version": "v2"
},
{
"created": "Mon, 16 Jun 2003 10:39:46 GMT",
"version": "v3"
}
] | 2009-11-10 | [
[
"Astone",
"Pia",
""
],
[
"D'Agostini",
"Giulio",
""
],
[
"D'Antonio",
"Sabrina",
""
]
] | Bayesian reasoning is applied to the data by the ROG Collaboration, in which gravitational wave (g.w.) signals are searched for in a coincidence experiment between Explorer and Nautilus. The use of Bayesian reasoning allows, under well defined hypotheses, even tiny pieces of evidence in favor of each model to be extracted from the data. The combination of the data of several experiments can therefore be performed in an optimal and efficient way. Some models for Galactic sources are considered and, within each model, the experimental result is summarized with the likelihood rescaled to the insensitivity limit value (``${\cal R}$ function''). The model comparison result is given in in terms of Bayes factors, which quantify how the ratio of beliefs about two alternative models are modified by the experimental observation |
1812.07373 | Mohammad Nouri-Zonoz | R. Gharechahi, J. Koohbor and M. Nouri-Zonoz | General relativistic analogs of Poisson's equation and gravitational
binding energy | 21 pages, REVTex, Accepted for publication in Physical Review D | Phys. Rev. D 99, 084046 (2019) | 10.1103/PhysRevD.99.084046 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Employing the quasi-Maxwell form of the Einstein field equations in the
context of gravitoelectromagnetism, we introduce a general relativistic analog
of Poisson's equation as a natural outcome of the corresponding spacetime
decomposition formalism. The active density introduced in this formalism, apart
from the matter-energy density and pressure, includes a third component which
is the gravitoelectromagnetic energy density. This general relativistic analog
of Poisson's equation is compared with another analog introduced by Ehlers et
al. in [1]. Introduction of the cosmological constant and its effect on the
active mass, are also discussed for both exterior and interior static
spacetimes. In the stationary case, we consider the Kerr spacetime with a
special choice for its interior metric.
| [
{
"created": "Sat, 8 Dec 2018 12:02:44 GMT",
"version": "v1"
},
{
"created": "Mon, 29 Apr 2019 09:51:41 GMT",
"version": "v2"
}
] | 2020-05-07 | [
[
"Gharechahi",
"R.",
""
],
[
"Koohbor",
"J.",
""
],
[
"Nouri-Zonoz",
"M.",
""
]
] | Employing the quasi-Maxwell form of the Einstein field equations in the context of gravitoelectromagnetism, we introduce a general relativistic analog of Poisson's equation as a natural outcome of the corresponding spacetime decomposition formalism. The active density introduced in this formalism, apart from the matter-energy density and pressure, includes a third component which is the gravitoelectromagnetic energy density. This general relativistic analog of Poisson's equation is compared with another analog introduced by Ehlers et al. in [1]. Introduction of the cosmological constant and its effect on the active mass, are also discussed for both exterior and interior static spacetimes. In the stationary case, we consider the Kerr spacetime with a special choice for its interior metric. |
0706.3080 | Kohkichi Konno | Kohkichi Konno, Toyoki Matsuyama, Satoshi Tanda | Does a black hole rotate in Chern-Simons modified gravity? | 4 pages, Accepted for publication in Phys. Rev. D | Phys.Rev.D76:024009,2007 | 10.1103/PhysRevD.76.024009 | null | gr-qc | null | Rotating black hole solutions in the (3+1)-dimensional Chern-Simons modified
gravity theory are discussed by taking account of perturbation around the
Schwarzschild solution. The zenith-angle dependence of a metric function
related to the frame-dragging effect is determined from a constraint equation
independently of a choice of the embedding coordinate. We find that at least
within the framework of the first-order perturbation method, the black hole
cannot rotate for finite black hole mass if the embedding coordinate is taken
to be a timelike vector. However, the rotation can be permitted in the limit of
$M/r \to 0$ (where $M$ is the black hole mass and $r$ is the radius). For a
spacelike vector, the rotation can also be permitted for any value of the black
hole mass.
| [
{
"created": "Thu, 21 Jun 2007 04:04:09 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Konno",
"Kohkichi",
""
],
[
"Matsuyama",
"Toyoki",
""
],
[
"Tanda",
"Satoshi",
""
]
] | Rotating black hole solutions in the (3+1)-dimensional Chern-Simons modified gravity theory are discussed by taking account of perturbation around the Schwarzschild solution. The zenith-angle dependence of a metric function related to the frame-dragging effect is determined from a constraint equation independently of a choice of the embedding coordinate. We find that at least within the framework of the first-order perturbation method, the black hole cannot rotate for finite black hole mass if the embedding coordinate is taken to be a timelike vector. However, the rotation can be permitted in the limit of $M/r \to 0$ (where $M$ is the black hole mass and $r$ is the radius). For a spacelike vector, the rotation can also be permitted for any value of the black hole mass. |
2310.07515 | \'Alvaro Parra L\'opez | Jose A. R. Cembranos, Luis J. Garay, \'Alvaro Parra-L\'opez and Jose
M. S\'anchez Vel\'azquez | Vector dark matter production during inflation and reheating | 23 pages, 9 figures | null | null | null | gr-qc hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational particle production of spectator fields due to the expansion
universe during the inflationary and reheating phases of the early universe is
of particular interest in the context of dark matter, since it allows to
constrain the properties of the dark candidate by comparing the density of
particles produced with the observed dark matter abundance. In such processes,
tachyonic instabilities arise as a consequence of the coupling to the
curvature, greatly enhancing mode production. In this work, we consider a
massive vector field that is coupled to the curvature scalar and the Ricci
tensor only, and study its gravitational production through inflation and
reheating. We show how the mechanism is more efficient than in the case of a
non-minimally coupled scalar field, giving rise to larger abundances. Moreover,
we analyze the importance of the coupling to the Ricci tensor, which increases
tachyonic instabilities in the system, and constrain the mass of the dark
particle and the values of the coupling constants by comparing the
corresponding abundance with observations
| [
{
"created": "Wed, 11 Oct 2023 14:13:09 GMT",
"version": "v1"
}
] | 2023-10-12 | [
[
"Cembranos",
"Jose A. R.",
""
],
[
"Garay",
"Luis J.",
""
],
[
"Parra-López",
"Álvaro",
""
],
[
"Velázquez",
"Jose M. Sánchez",
""
]
] | Gravitational particle production of spectator fields due to the expansion universe during the inflationary and reheating phases of the early universe is of particular interest in the context of dark matter, since it allows to constrain the properties of the dark candidate by comparing the density of particles produced with the observed dark matter abundance. In such processes, tachyonic instabilities arise as a consequence of the coupling to the curvature, greatly enhancing mode production. In this work, we consider a massive vector field that is coupled to the curvature scalar and the Ricci tensor only, and study its gravitational production through inflation and reheating. We show how the mechanism is more efficient than in the case of a non-minimally coupled scalar field, giving rise to larger abundances. Moreover, we analyze the importance of the coupling to the Ricci tensor, which increases tachyonic instabilities in the system, and constrain the mass of the dark particle and the values of the coupling constants by comparing the corresponding abundance with observations |
1110.0530 | Tjonnie Guang Feng Li | T. G. F. Li, W. Del Pozzo, S. Vitale, C. Van Den Broeck, M. Agathos,
J. Veitch, K. Grover, T. Sidery, R. Sturani, A. Vecchio | Towards a generic test of the strong field dynamics of general
relativity using compact binary coalescence | 26 pages, 23 figures, Accepted by PRD | Phys. Rev. D 85, 082003 (2012) | 10.1103/PhysRevD.85.082003 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Coalescences of binary neutron stars and/or black holes are amongst the most
likely gravitational-wave signals to be observed in ground based
interferometric detectors. Apart from the astrophysical importance of their
detection, they will also provide us with our very first empirical access to
the genuinely strong-field dynamics of General Relativity (GR). We present a
new framework based on Bayesian model selection aimed at detecting deviations
from GR, subject to the constraints of the Advanced Virgo and LIGO detectors.
The method tests the consistency of coefficients appearing in the waveform with
the predictions made by GR, without relying on any specific alternative theory
of gravity. The framework is suitable for low signal-to-noise ratio events
through the construction of multiple subtests, most of which involve only a
limited number of coefficients. It also naturally allows for the combination of
information from multiple sources to increase one's confidence in GR or a
violation thereof. We expect it to be capable of finding a wide range of
possible deviations from GR, including ones which in principle cannot be
accommodated by the model waveforms, on condition that the induced change in
phase at frequencies where the detectors are the most sensitive is comparable
to the effect of a few percent change in one or more of the low-order
post-Newtonian phase coefficients. In principle the framework can be used with
any GR waveform approximant, with arbitrary parameterized deformations, to
serve as model waveforms. In order to illustrate the workings of the method, we
perform a range of numerical experiments in which simulated gravitational waves
modeled in the restricted post-Newtonian, stationary phase approximation are
added to Gaussian and stationary noise that follows the expected Advanced
LIGO/Virgo noise curves.
| [
{
"created": "Mon, 3 Oct 2011 22:06:11 GMT",
"version": "v1"
},
{
"created": "Sun, 4 Mar 2012 12:28:05 GMT",
"version": "v2"
}
] | 2012-05-07 | [
[
"Li",
"T. G. F.",
""
],
[
"Del Pozzo",
"W.",
""
],
[
"Vitale",
"S.",
""
],
[
"Broeck",
"C. Van Den",
""
],
[
"Agathos",
"M.",
""
],
[
"Veitch",
"J.",
""
],
[
"Grover",
"K.",
""
],
[
"Sidery",
"T... | Coalescences of binary neutron stars and/or black holes are amongst the most likely gravitational-wave signals to be observed in ground based interferometric detectors. Apart from the astrophysical importance of their detection, they will also provide us with our very first empirical access to the genuinely strong-field dynamics of General Relativity (GR). We present a new framework based on Bayesian model selection aimed at detecting deviations from GR, subject to the constraints of the Advanced Virgo and LIGO detectors. The method tests the consistency of coefficients appearing in the waveform with the predictions made by GR, without relying on any specific alternative theory of gravity. The framework is suitable for low signal-to-noise ratio events through the construction of multiple subtests, most of which involve only a limited number of coefficients. It also naturally allows for the combination of information from multiple sources to increase one's confidence in GR or a violation thereof. We expect it to be capable of finding a wide range of possible deviations from GR, including ones which in principle cannot be accommodated by the model waveforms, on condition that the induced change in phase at frequencies where the detectors are the most sensitive is comparable to the effect of a few percent change in one or more of the low-order post-Newtonian phase coefficients. In principle the framework can be used with any GR waveform approximant, with arbitrary parameterized deformations, to serve as model waveforms. In order to illustrate the workings of the method, we perform a range of numerical experiments in which simulated gravitational waves modeled in the restricted post-Newtonian, stationary phase approximation are added to Gaussian and stationary noise that follows the expected Advanced LIGO/Virgo noise curves. |
2105.09971 | Sk Jahanur Hoque | Sumanta Chakraborty, Sk Jahanur Hoque, Roberto Oliveri | Gravitational multipole moments for asymptotically de Sitter spacetimes | 35 pages, 1 figure, minor changes, version accepted for publication
in PRD | Phys. Rev. D 104, 064019 (2021) | 10.1103/PhysRevD.104.064019 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide a prescription to compute the gravitational multipole moments of
compact objects for asymptotically de Sitter spacetimes. Our prescription
builds upon a recent definition of the gravitational multipole moments in terms
of Noether charges associated to specific vector fields, within the residual
harmonic gauge, dubbed multipole symmetries. We first derive the multipole
symmetries for spacetimes which are asymptotically de Sitter; we also show that
these symmetry vector fields eliminate the non-propagating degrees of freedom
from the linearized gravitational wave equation in a suitable gauge. We then
apply our prescription to the Kerr-de Sitter black hole and compute its
multipole structure. Our result recovers the Geroch-Hansen moments of the Kerr
black hole in the limit of vanishing cosmological constant.
| [
{
"created": "Thu, 20 May 2021 18:04:54 GMT",
"version": "v1"
},
{
"created": "Sat, 11 Sep 2021 22:33:20 GMT",
"version": "v2"
}
] | 2021-09-14 | [
[
"Chakraborty",
"Sumanta",
""
],
[
"Hoque",
"Sk Jahanur",
""
],
[
"Oliveri",
"Roberto",
""
]
] | We provide a prescription to compute the gravitational multipole moments of compact objects for asymptotically de Sitter spacetimes. Our prescription builds upon a recent definition of the gravitational multipole moments in terms of Noether charges associated to specific vector fields, within the residual harmonic gauge, dubbed multipole symmetries. We first derive the multipole symmetries for spacetimes which are asymptotically de Sitter; we also show that these symmetry vector fields eliminate the non-propagating degrees of freedom from the linearized gravitational wave equation in a suitable gauge. We then apply our prescription to the Kerr-de Sitter black hole and compute its multipole structure. Our result recovers the Geroch-Hansen moments of the Kerr black hole in the limit of vanishing cosmological constant. |
2405.13784 | Krzysztof Andrzejewski | K. Andrzejewski | Revisiting the dynamics of a charged spinning body in curved spacetime | 16 pages, no figures; comments and references added | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We analyze the motion of the spinning body (in the pole-dipole approximation)
in the gravitational and electromagnetic fields described by the
Mathisson-Papapetrou-Dixon-Souriau equations. First, we define a novel spin
supplementary condition for the electromagnetic interactions which generalizes
the one proposed by Ohashi-Kyrian-Semer\'ak for gravity. As a result, we get
the whole family of charged spinning particle models in the curved spacetime
with remarkably simple dynamics (momentum and velocity are parallel). Applying
the reparametrization procedure, for a specific dipole moment, we obtain
equations of motion with constant mass and gyromagnetic factor. Next, we show
that these equations follows from an effective Hamiltonian formalism,
previously interpreted as a classical model of the charged Dirac particle.
| [
{
"created": "Wed, 22 May 2024 16:10:44 GMT",
"version": "v1"
},
{
"created": "Wed, 5 Jun 2024 16:26:07 GMT",
"version": "v2"
}
] | 2024-06-06 | [
[
"Andrzejewski",
"K.",
""
]
] | We analyze the motion of the spinning body (in the pole-dipole approximation) in the gravitational and electromagnetic fields described by the Mathisson-Papapetrou-Dixon-Souriau equations. First, we define a novel spin supplementary condition for the electromagnetic interactions which generalizes the one proposed by Ohashi-Kyrian-Semer\'ak for gravity. As a result, we get the whole family of charged spinning particle models in the curved spacetime with remarkably simple dynamics (momentum and velocity are parallel). Applying the reparametrization procedure, for a specific dipole moment, we obtain equations of motion with constant mass and gyromagnetic factor. Next, we show that these equations follows from an effective Hamiltonian formalism, previously interpreted as a classical model of the charged Dirac particle. |
2008.13177 | Metin Arik | Onder Dunya and Metin Arik | A New Approach to Flatness, Horizon and Late-time Accelerating Expansion
Problems on the basis of Mach Principle | 27 pages, 1 figure, matches the published version | Physics of the Dark Universe 41 (2023) 101252 | 10.1016/j.dark.2023.101252 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Based on the idea that the components of a cosmological metric may be
determined by the total gravitational potential of the universe, the scalar
field $\phi=1/G$ in the Jordan-Brans-Dicke (JBD) theory is introduced as
evolving with the inverse square of the scale factor. Since the gravitational
potential is related to the field $\phi$ resulting from Mach's principle and
depends on time due to the expansion of space, the temporal evolution of the
field should be in accord with the evolution of time and space intervals in the
metric tensor. For the same reason, the time dependence of the field makes
these comoving intervals relative for different points on the time axis. Thus,
it is shown that introduction of the cosmic gravitational potential as a time
dependent scalar field proportional to $1/a^2$ may resolve the flatness, the
horizon and the late-time accelerating expansion problems of the standard model
of cosmology. The luminosity distance vs redshift data of Type Ia supernovae is
in agreement with this approach.
| [
{
"created": "Sun, 30 Aug 2020 14:01:19 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Apr 2022 18:31:51 GMT",
"version": "v2"
},
{
"created": "Tue, 16 May 2023 20:36:45 GMT",
"version": "v3"
}
] | 2023-05-18 | [
[
"Dunya",
"Onder",
""
],
[
"Arik",
"Metin",
""
]
] | Based on the idea that the components of a cosmological metric may be determined by the total gravitational potential of the universe, the scalar field $\phi=1/G$ in the Jordan-Brans-Dicke (JBD) theory is introduced as evolving with the inverse square of the scale factor. Since the gravitational potential is related to the field $\phi$ resulting from Mach's principle and depends on time due to the expansion of space, the temporal evolution of the field should be in accord with the evolution of time and space intervals in the metric tensor. For the same reason, the time dependence of the field makes these comoving intervals relative for different points on the time axis. Thus, it is shown that introduction of the cosmic gravitational potential as a time dependent scalar field proportional to $1/a^2$ may resolve the flatness, the horizon and the late-time accelerating expansion problems of the standard model of cosmology. The luminosity distance vs redshift data of Type Ia supernovae is in agreement with this approach. |
gr-qc/9405014 | Peter Breitenlohner | P. Breitenlohner and D. Maison | On the Limiting Solution of the Bartnik-McKinnon Family | 7 pages, MPI PhT/94-20 | Commun.Math.Phys.171:685-690,1995 | 10.1007/BF02104684 | null | gr-qc | null | We analyze the limiting solution of the Bartnik-McKinnon family and show that
its exterior is an extremal Reissner-Nordstr{\o}m black hole and not a new type
of non-abelian black hole as claimed in a recent article by Smoller and
Wasserman.
| [
{
"created": "Fri, 6 May 1994 15:58:16 GMT",
"version": "v1"
}
] | 2010-11-01 | [
[
"Breitenlohner",
"P.",
""
],
[
"Maison",
"D.",
""
]
] | We analyze the limiting solution of the Bartnik-McKinnon family and show that its exterior is an extremal Reissner-Nordstr{\o}m black hole and not a new type of non-abelian black hole as claimed in a recent article by Smoller and Wasserman. |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.