id stringlengths 9 13 | submitter stringlengths 1 64 ⌀ | authors stringlengths 5 22.9k | title stringlengths 4 245 | comments stringlengths 1 548 ⌀ | journal-ref stringlengths 4 362 ⌀ | doi stringlengths 12 82 ⌀ | report-no stringlengths 2 281 ⌀ | categories stringclasses 793 values | license stringclasses 9 values | orig_abstract stringlengths 24 1.95k | versions listlengths 1 30 | update_date stringlengths 10 10 | authors_parsed listlengths 1 1.74k | abstract stringlengths 21 1.95k |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
gr-qc/9504023 | Mathias Pillin | Mathias Pillin | Selfdual 2-form formulation of gravity and classification of
energy-momentum tensors | title changed, extended version | Class. Quant. Grav. 13 (1996) 2379 | 10.1088/0264-9381/13/8/020 | null | gr-qc | null | It is shown how the different irreducibility classes of the energy-momentum
tensor allow for a Lagrangian formulation of the gravity-matter system using a
selfdual 2-form as a basic variable. It is pointed out what kind of
difficulties arise when attempting to construct a pure spin-connection
formulation of the gravity-matter system. Ambiguities in the formulation
especially concerning the need for constraints are clarified.
| [
{
"created": "Mon, 17 Apr 1995 01:43:50 GMT",
"version": "v1"
},
{
"created": "Tue, 17 Dec 1996 04:04:48 GMT",
"version": "v2"
}
] | 2009-10-28 | [
[
"Pillin",
"Mathias",
""
]
] | It is shown how the different irreducibility classes of the energy-momentum tensor allow for a Lagrangian formulation of the gravity-matter system using a selfdual 2-form as a basic variable. It is pointed out what kind of difficulties arise when attempting to construct a pure spin-connection formulation of the gravity-matter system. Ambiguities in the formulation especially concerning the need for constraints are clarified. |
2112.13140 | Peter Cameron | Peter Cameron, Piotr T. Chru\'sciel | Asymptotic flatness in higher dimensions | null | J. Math. Phys. 63, 032501 (2022) | 10.1063/5.0083728 | null | gr-qc math.DG | http://creativecommons.org/licenses/by/4.0/ | We show that $(n+1)$-dimensional Myers-Perry metrics, $n\geq4$, have a
conformal completion at spacelike infinity of $C^{n-3,1}$ differentiability
class, and that the result is optimal in even spacetime dimensions. The
associated asymptotic symmetries are presented.
| [
{
"created": "Fri, 24 Dec 2021 20:50:21 GMT",
"version": "v1"
},
{
"created": "Mon, 18 Dec 2023 15:19:12 GMT",
"version": "v2"
}
] | 2023-12-19 | [
[
"Cameron",
"Peter",
""
],
[
"Chruściel",
"Piotr T.",
""
]
] | We show that $(n+1)$-dimensional Myers-Perry metrics, $n\geq4$, have a conformal completion at spacelike infinity of $C^{n-3,1}$ differentiability class, and that the result is optimal in even spacetime dimensions. The associated asymptotic symmetries are presented. |
gr-qc/9610076 | Philip Papadopoulos | Philippos Papadopoulos, Pablo Laguna | Cauchy-characteristic Evolution of Einstein-Klein-Gordon Systems: The
Black Hole Regime | To appear in Phys. Rev. D, 9 pages, revtex, 5 figures available at
http://www.astro.psu.edu/users/nr/preprints.html | Phys.Rev. D55 (1997) 2038-2043 | 10.1103/PhysRevD.55.2038 | CGPG-96/10-3 | gr-qc | null | The Cauchy+characteristic matching (CCM) problem for the scalar wave equation
is investigated in the background geometry of a Schwarzschild black hole.
Previously reported work developed the CCM framework for the coupled
Einstein-Klein-Gordon system of equations, assuming a regular center of
symmetry. Here, the time evolution after the formation of a black hole is
pursued, using a CCM formulation of the governing equations perturbed around
the Schwarzschild background. An extension of the matching scheme allows for
arbitrary matching boundary motion across the coordinate grid. As a proof of
concept, the late time behavior of the dynamics of the scalar field is
explored. The power-law tails in both the time-like and null infinity limits
are verified.
| [
{
"created": "Thu, 31 Oct 1996 21:59:53 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Papadopoulos",
"Philippos",
""
],
[
"Laguna",
"Pablo",
""
]
] | The Cauchy+characteristic matching (CCM) problem for the scalar wave equation is investigated in the background geometry of a Schwarzschild black hole. Previously reported work developed the CCM framework for the coupled Einstein-Klein-Gordon system of equations, assuming a regular center of symmetry. Here, the time evolution after the formation of a black hole is pursued, using a CCM formulation of the governing equations perturbed around the Schwarzschild background. An extension of the matching scheme allows for arbitrary matching boundary motion across the coordinate grid. As a proof of concept, the late time behavior of the dynamics of the scalar field is explored. The power-law tails in both the time-like and null infinity limits are verified. |
1201.4373 | Mahdi Godazgar | Mahdi Godazgar and Harvey S. Reall | Peeling of the Weyl tensor and gravitational radiation in higher
dimensions | 15 pages; minor corrections; Phys. Rev. D: Vol.85, No.8 (2012) | null | 10.1103/PhysRevD.85.084021 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The peeling behaviour of the Weyl tensor near null infinity is determined for
an asymptotically flat higher dimensional spacetime. The result is
qualitatively different from the peeling property in 4d. To leading order, the
Weyl tensor is type N. The first subleading term is type II. The next term is
algebraically general in 6 or more dimensions but in 5 dimensions another type
N term appears before the algebraically general term. The Bondi energy flux is
written in terms of "Newman-Penrose" Weyl components.
| [
{
"created": "Fri, 20 Jan 2012 19:35:12 GMT",
"version": "v1"
},
{
"created": "Sun, 22 Apr 2012 17:04:03 GMT",
"version": "v2"
}
] | 2013-05-30 | [
[
"Godazgar",
"Mahdi",
""
],
[
"Reall",
"Harvey S.",
""
]
] | The peeling behaviour of the Weyl tensor near null infinity is determined for an asymptotically flat higher dimensional spacetime. The result is qualitatively different from the peeling property in 4d. To leading order, the Weyl tensor is type N. The first subleading term is type II. The next term is algebraically general in 6 or more dimensions but in 5 dimensions another type N term appears before the algebraically general term. The Bondi energy flux is written in terms of "Newman-Penrose" Weyl components. |
1504.01714 | Anirban Ain | Anirban Ain, Prathamesh Dalvi and Sanjit Mitra | Fast Gravitational Wave Radiometry using Data Folding | 11 pages, 3 figures, 1 table | Phys. Rev. D 92, 022003 (2015) | 10.1103/PhysRevD.92.022003 | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational Waves (GWs) from the early universe and unresolved
astrophysical sources are expected to create a stochastic GW background (SGWB).
The GW radiometer algorithm is well suited to probe such a background using
data from ground based laser interferometric detectors. Radiometer analysis can
be performed in different bases, e.g., isotropic, pixel or spherical harmonic.
Each of these analyses possesses a common temporal symmetry which we exploit
here to fold the whole dataset for every detector pair, typically a few hundred
to a thousand days of data, to only one sidereal day, without any compromise in
precision. We develop the algebra and a software pipeline needed to fold data,
accounting for the effect of overlapping windows and non-stationary noise. We
implement this on LIGO's fifth science run data and validate it by performing a
standard anisotropic SGWB search on both folded and unfolded data. Folded data
not only leads to orders of magnitude reduction in computation cost, but it
results in a conveniently small data volume of few gigabytes, making it
possible to perform an actual analysis on a personal computer, as well as easy
movement of data. A few important analyses, yet unaccomplished due to
computational limitations, will now become feasible. Folded data, being
independent of the radiometer basis, will also be useful in reducing processing
redundancies in multiple searches and provide a common ground for mutual
consistency checks. Most importantly, folded data will allow vast amount of
experimentation with existing searches and provide substantial help in
developing new strategies to find unknown sources.
| [
{
"created": "Tue, 7 Apr 2015 19:39:10 GMT",
"version": "v1"
}
] | 2015-09-23 | [
[
"Ain",
"Anirban",
""
],
[
"Dalvi",
"Prathamesh",
""
],
[
"Mitra",
"Sanjit",
""
]
] | Gravitational Waves (GWs) from the early universe and unresolved astrophysical sources are expected to create a stochastic GW background (SGWB). The GW radiometer algorithm is well suited to probe such a background using data from ground based laser interferometric detectors. Radiometer analysis can be performed in different bases, e.g., isotropic, pixel or spherical harmonic. Each of these analyses possesses a common temporal symmetry which we exploit here to fold the whole dataset for every detector pair, typically a few hundred to a thousand days of data, to only one sidereal day, without any compromise in precision. We develop the algebra and a software pipeline needed to fold data, accounting for the effect of overlapping windows and non-stationary noise. We implement this on LIGO's fifth science run data and validate it by performing a standard anisotropic SGWB search on both folded and unfolded data. Folded data not only leads to orders of magnitude reduction in computation cost, but it results in a conveniently small data volume of few gigabytes, making it possible to perform an actual analysis on a personal computer, as well as easy movement of data. A few important analyses, yet unaccomplished due to computational limitations, will now become feasible. Folded data, being independent of the radiometer basis, will also be useful in reducing processing redundancies in multiple searches and provide a common ground for mutual consistency checks. Most importantly, folded data will allow vast amount of experimentation with existing searches and provide substantial help in developing new strategies to find unknown sources. |
1506.08823 | Marit Sandstad | Florian K\"uhnel and Marit Sandstad | Baryon number conservation in Bose-Einstein condensate black holes | 5 pages, no figures | Phys. Rev. D 92, 124028 (2015) | 10.1103/PhysRevD.92.124028 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Primordial black holes are studied in the Bose-Einstein condensate
description of space-time. The question of baryon-number conservation is
investigated with emphasis on possible formation of bound states of the
system's remaining captured baryons. This leads to distinct predictions for
both the formation time, which for the naively natural assumptions is shown to
lie between $10^{-12}\.\srm$ to $10^{12}\.\srm$ after Big Bang, as well as for
the remnant's mass, yielding approximately $3 \cdot 10^{23}\.{\rm kg}$ in the
same scheme. The consequences for astrophysically formed black holes are also
considered.
| [
{
"created": "Mon, 29 Jun 2015 20:00:35 GMT",
"version": "v1"
},
{
"created": "Fri, 18 Dec 2015 15:04:33 GMT",
"version": "v2"
}
] | 2015-12-23 | [
[
"Kühnel",
"Florian",
""
],
[
"Sandstad",
"Marit",
""
]
] | Primordial black holes are studied in the Bose-Einstein condensate description of space-time. The question of baryon-number conservation is investigated with emphasis on possible formation of bound states of the system's remaining captured baryons. This leads to distinct predictions for both the formation time, which for the naively natural assumptions is shown to lie between $10^{-12}\.\srm$ to $10^{12}\.\srm$ after Big Bang, as well as for the remnant's mass, yielding approximately $3 \cdot 10^{23}\.{\rm kg}$ in the same scheme. The consequences for astrophysically formed black holes are also considered. |
gr-qc/9603015 | Julio Cesar Fabris | J.P. Baptista, J.C. Fabris and S.V.B. Goncalves (Universidade Federal
do Espirito Santo - Brazil) | Density Perturbations in the Brans-Dicke Theory | 26 pages, latex file | null | 10.1007/BF00645648 | DF-UFES/96 | gr-qc | null | We analyse the fate of density perturbation in the Brans-Dicke Theory, giving
a general classification of the solutions of the perturbed equations when the
scale factor of the background evolves as a power law. We study with details
the cases of vacuum, inflation, radiation and incoherent matter. We find, for
the a negative Brans-Dicke parameter, a significant amplification of
perturbations.
| [
{
"created": "Wed, 6 Mar 1996 18:09:17 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Baptista",
"J. P.",
"",
"Universidade Federal\n do Espirito Santo - Brazil"
],
[
"Fabris",
"J. C.",
"",
"Universidade Federal\n do Espirito Santo - Brazil"
],
[
"Goncalves",
"S. V. B.",
"",
"Universidade Federal\n do Espirito Santo - Brazil"
]
] | We analyse the fate of density perturbation in the Brans-Dicke Theory, giving a general classification of the solutions of the perturbed equations when the scale factor of the background evolves as a power law. We study with details the cases of vacuum, inflation, radiation and incoherent matter. We find, for the a negative Brans-Dicke parameter, a significant amplification of perturbations. |
2012.04614 | Antonio De Padua Santos | Joao Chakrian and Antonio de Padua Santos | Black String Thermodynamics in Noncommutative Spacetime: Anomaly and
Phase Transition | 13 pages, 8 figures | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | Black holes have been a subject of investigation over years not only because
they have interesting physical properties, but also because they seem to be the
appropriate tool for studying gravity in quantum scale. Although a lot of
effort has been made to understand the aspects of spacetime on the quantum
scale, the approach which includes noncommutativity of spacetime proves to be
promising among several possibilities. In this paper, we use the
Hamilton-Jacobi method to study the thermodynamic properties of cylindrical
black holes (black strings) in noncommutative spacetime. It is also
investigated the behavior of the black string in the presence of back reaction
as well as its influence on the system can be understood as an anomaly. This
work aims to provide understanding about black strings thermodynamics in
noncommutative spacetime since this scale of spacetime is important for the
comprehension of the relation between quantum mechanics and general relativity.
| [
{
"created": "Tue, 8 Dec 2020 18:38:59 GMT",
"version": "v1"
}
] | 2020-12-09 | [
[
"Chakrian",
"Joao",
""
],
[
"Santos",
"Antonio de Padua",
""
]
] | Black holes have been a subject of investigation over years not only because they have interesting physical properties, but also because they seem to be the appropriate tool for studying gravity in quantum scale. Although a lot of effort has been made to understand the aspects of spacetime on the quantum scale, the approach which includes noncommutativity of spacetime proves to be promising among several possibilities. In this paper, we use the Hamilton-Jacobi method to study the thermodynamic properties of cylindrical black holes (black strings) in noncommutative spacetime. It is also investigated the behavior of the black string in the presence of back reaction as well as its influence on the system can be understood as an anomaly. This work aims to provide understanding about black strings thermodynamics in noncommutative spacetime since this scale of spacetime is important for the comprehension of the relation between quantum mechanics and general relativity. |
1503.08640 | Kirill Krasnov | Yannick Herfray and Kirill Krasnov | New first order Lagrangian for General Relativity | 4 pages | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We describe a new BF-type first-order in derivatives Lagrangian for General
Relativity. The Lagrangian depends on a connection field as well as a
Lie-algebra valued two-form field, with no other fields present. There are two
free parameters, which translate into the cosmological constant and the
coefficient in front of a topological term. When one of the parameters is set
to zero, the theory becomes topological. When the other parameter is zero, the
theory reduces to the (anti-) self-dual gravity. Thus, our new Lagrangian
interpolates between the topological and anti-self-dual gravities. It also
interprets GR as the (anti-) self-dual gravity with an extra quadratic in the
auxiliary two-form field term added to the Lagrangian, precisely paralleling
the situation in Yang-Mills theory.
| [
{
"created": "Mon, 30 Mar 2015 11:24:09 GMT",
"version": "v1"
}
] | 2015-03-31 | [
[
"Herfray",
"Yannick",
""
],
[
"Krasnov",
"Kirill",
""
]
] | We describe a new BF-type first-order in derivatives Lagrangian for General Relativity. The Lagrangian depends on a connection field as well as a Lie-algebra valued two-form field, with no other fields present. There are two free parameters, which translate into the cosmological constant and the coefficient in front of a topological term. When one of the parameters is set to zero, the theory becomes topological. When the other parameter is zero, the theory reduces to the (anti-) self-dual gravity. Thus, our new Lagrangian interpolates between the topological and anti-self-dual gravities. It also interprets GR as the (anti-) self-dual gravity with an extra quadratic in the auxiliary two-form field term added to the Lagrangian, precisely paralleling the situation in Yang-Mills theory. |
2406.12055 | Olindo Zanotti | Michael Dumbser, Olindo Zanotti, Gabriella Puppo | A monolithic first--order BSSNOK formulation of the Einstein--Euler
equations and its solution with path-conservative finite difference CWENO
schemes | 26 pages, 14 figures | null | null | null | gr-qc astro-ph.HE cs.NA math.NA | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a new, monolithic first--order (both in time and space) BSSNOK
formulation of the coupled Einstein--Euler equations. The entire system of
hyperbolic PDEs is solved in a completely unified manner via one single
numerical scheme applied to both the conservative sector of the matter part and
to the first--order strictly non--conservative sector of the spacetime
evolution. The coupling between matter and space-time is achieved via algebraic
source terms. The numerical scheme used for the solution of the new monolithic
first order formulation is a path-conservative central WENO (CWENO) finite
difference scheme, with suitable insertions to account for the presence of the
non--conservative terms. By solving several crucial tests of numerical general
relativity, including a stable neutron star, Riemann problems in relativistic
matter with shock waves and the stable long-time evolution of single and binary
puncture black holes up and beyond the binary merger, we show that our new
CWENO scheme, introduced two decades ago for the compressible Euler equations
of gas dynamics, can be successfully applied also to numerical general
relativity, solving all equations at the same time with one single numerical
method. In the future the new monolithic approach proposed in this paper may
become an attractive alternative to traditional methods that couple central
finite difference schemes with Kreiss-Oliger dissipation for the space-time
part with totally different TVD schemes for the matter evolution and which are
currently the state of the art in the field.
| [
{
"created": "Mon, 17 Jun 2024 19:47:06 GMT",
"version": "v1"
}
] | 2024-06-19 | [
[
"Dumbser",
"Michael",
""
],
[
"Zanotti",
"Olindo",
""
],
[
"Puppo",
"Gabriella",
""
]
] | We present a new, monolithic first--order (both in time and space) BSSNOK formulation of the coupled Einstein--Euler equations. The entire system of hyperbolic PDEs is solved in a completely unified manner via one single numerical scheme applied to both the conservative sector of the matter part and to the first--order strictly non--conservative sector of the spacetime evolution. The coupling between matter and space-time is achieved via algebraic source terms. The numerical scheme used for the solution of the new monolithic first order formulation is a path-conservative central WENO (CWENO) finite difference scheme, with suitable insertions to account for the presence of the non--conservative terms. By solving several crucial tests of numerical general relativity, including a stable neutron star, Riemann problems in relativistic matter with shock waves and the stable long-time evolution of single and binary puncture black holes up and beyond the binary merger, we show that our new CWENO scheme, introduced two decades ago for the compressible Euler equations of gas dynamics, can be successfully applied also to numerical general relativity, solving all equations at the same time with one single numerical method. In the future the new monolithic approach proposed in this paper may become an attractive alternative to traditional methods that couple central finite difference schemes with Kreiss-Oliger dissipation for the space-time part with totally different TVD schemes for the matter evolution and which are currently the state of the art in the field. |
1006.4644 | Leone Bosi | Leone B. Bosi | cuInspiral: prototype gravitational waves detection pipeline fully coded
on GPU using CUDA | null | null | null | null | gr-qc physics.comp-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we report the prototype of the first coalescing binary
detection pipeline fully implemented on NVIDIA GPU hardware accelerators. The
code has been embedded in a GPU library, called cuInspiral and has been
developed under CUDA framework. The library contains for example a PN
gravitational wave signal generator, matched filtering/FFT and detection
algorithms that have been profiled and compared with the corresponding CPU code
with dedicated benchmark in order to provide gain factor respect to the
standard CPU implementation. In the paper we present performances and accuracy
results about some of the main important elements of the pipeline,
demonstrating the feasibility and the chance of obtain an impressive computing
gain from these new many-core architectures in the perspective of the second
and third generations of gravitational wave detectors.
| [
{
"created": "Wed, 16 Jun 2010 22:25:04 GMT",
"version": "v1"
}
] | 2010-06-25 | [
[
"Bosi",
"Leone B.",
""
]
] | In this paper we report the prototype of the first coalescing binary detection pipeline fully implemented on NVIDIA GPU hardware accelerators. The code has been embedded in a GPU library, called cuInspiral and has been developed under CUDA framework. The library contains for example a PN gravitational wave signal generator, matched filtering/FFT and detection algorithms that have been profiled and compared with the corresponding CPU code with dedicated benchmark in order to provide gain factor respect to the standard CPU implementation. In the paper we present performances and accuracy results about some of the main important elements of the pipeline, demonstrating the feasibility and the chance of obtain an impressive computing gain from these new many-core architectures in the perspective of the second and third generations of gravitational wave detectors. |
gr-qc/0001094 | Maurizio Gasperini | M. Gasperini | Signal-to-noise ratio for a stochastic background of massive relic
particles | 10 pages, Latex, two figures included using epsfig | Phys.Lett. B477 (2000) 242-247 | 10.1016/S0370-2693(00)00195-7 | BA-TH/00-374 | gr-qc astro-ph hep-ph | null | We estimate the signal-to-noise ratio for two gravitational detectors
interacting with a stochastic background of massive scalar waves. We find that
the present experimental level of sensitivity could be already enough to detect
a signal from a light but non-relativistic component of dark matter, even if
the coupling is weak enough to exclude observable deviations from standard
gravitational interactions, provided the mass is not too far from the
sensitivity and overlapping band of the two detectors.
| [
{
"created": "Fri, 28 Jan 2000 13:10:47 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Gasperini",
"M.",
""
]
] | We estimate the signal-to-noise ratio for two gravitational detectors interacting with a stochastic background of massive scalar waves. We find that the present experimental level of sensitivity could be already enough to detect a signal from a light but non-relativistic component of dark matter, even if the coupling is weak enough to exclude observable deviations from standard gravitational interactions, provided the mass is not too far from the sensitivity and overlapping band of the two detectors. |
1509.07916 | Jose Edgar Madriz Aguilar | M. L. Pucheu, C. Romero, M. Bellini and Jos\'e Edgar Madriz Aguilar | Gauge invariant fluctuations of the metric during inflation from new
scalar-tensor Weyl-Integrable gravity model | 9 pages, no figures. This is a revised version accepted for
publication in Physical Review D | Phys. Rev. D 94, 064075 (2016) | 10.1103/PhysRevD.94.064075 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate gauge invariant scalar fluctuations of the metric during
inflation in a non-perturbative formalism in the framework of a recently
introduced scalar-tensor theory of gravity formulated on a Weyl-Integrable
geometry. We found that the Weyl scalar field can play the role of the inflaton
field in this theory. As an application we study the case of a power law
inflation. In this case the quasi-scale invariance of the spectrum for scalar
fluctuations of the metric is achieved for determined values of the $\omega$
parameter of the scalar-tensor theory. In our formalism the physical inflaton
field has a geometrical origin.
| [
{
"created": "Fri, 25 Sep 2015 22:49:33 GMT",
"version": "v1"
},
{
"created": "Sun, 13 Mar 2016 15:06:40 GMT",
"version": "v2"
},
{
"created": "Sat, 6 Aug 2016 20:01:41 GMT",
"version": "v3"
}
] | 2016-10-05 | [
[
"Pucheu",
"M. L.",
""
],
[
"Romero",
"C.",
""
],
[
"Bellini",
"M.",
""
],
[
"Aguilar",
"José Edgar Madriz",
""
]
] | We investigate gauge invariant scalar fluctuations of the metric during inflation in a non-perturbative formalism in the framework of a recently introduced scalar-tensor theory of gravity formulated on a Weyl-Integrable geometry. We found that the Weyl scalar field can play the role of the inflaton field in this theory. As an application we study the case of a power law inflation. In this case the quasi-scale invariance of the spectrum for scalar fluctuations of the metric is achieved for determined values of the $\omega$ parameter of the scalar-tensor theory. In our formalism the physical inflaton field has a geometrical origin. |
2309.00439 | Sushovan Mondal | Sushovan Mondal and Manjari Bagchi | f-mode oscillations of anisotropic neutron stars in full general
relativity | 18 pages, 14 figures, 1 table; abstract shortened as per arXiv
requirement (see pdf version) | null | null | null | gr-qc astro-ph.HE astro-ph.SR | http://creativecommons.org/licenses/by/4.0/ | We investigate f-mode oscillations of static anisotropic stable neutron stars
within the framework of full general relativity. We present equations governing
unperturbed stellar structures and oscillations with an ansatz to account for
the anisotropy. We solve those equations for two different equations of states.
We see that, moderately anisotropic neutron stars with the tangential pressure
larger than the radial pressure can give more massive neutron stars than the
isotropic or very anisotropic ones. We find that the frequency of the f-mode
exhibits a linear relationship with the square root of the average density of
the stars and the slope of the fit depends on the anisotropic strength. For any
given value of the anisotropic strength, the frequency increases with the
increase of the mass of the neutron star, linearly for lower masses, and
rapidly at higher masses. However, this non-linear rise in the frequency with
the mass is not prominent when the radial pressure is larger than the
tangential pressure. For a fixed value of a small mass, higher anisotropy leads
to a larger value of the frequency, but when the fixed mass is above a
threshold value, higher anisotropy leads to a smaller value of the frequency.
The nature of the variation in the frequency with the change in the anisotropic
strength is similar for the two equations of state, but for a fixed mass and
the same amount of the anisotropy, the softer equations of state gives higher
frequency. We also find that the damping time of the f-mode oscillation
decreases as the mass of the neutron star increases for all values of the
anisotropic strength. For a fixed mass of the neutron star and for the same
amount of the anisotropy, the value of the damping time is lower for the softer
equation of state, but the nature of the variation in the damping time with the
change in the anisotropic strength is similar.
| [
{
"created": "Fri, 1 Sep 2023 13:14:23 GMT",
"version": "v1"
},
{
"created": "Mon, 29 Jan 2024 06:00:35 GMT",
"version": "v2"
}
] | 2024-01-30 | [
[
"Mondal",
"Sushovan",
""
],
[
"Bagchi",
"Manjari",
""
]
] | We investigate f-mode oscillations of static anisotropic stable neutron stars within the framework of full general relativity. We present equations governing unperturbed stellar structures and oscillations with an ansatz to account for the anisotropy. We solve those equations for two different equations of states. We see that, moderately anisotropic neutron stars with the tangential pressure larger than the radial pressure can give more massive neutron stars than the isotropic or very anisotropic ones. We find that the frequency of the f-mode exhibits a linear relationship with the square root of the average density of the stars and the slope of the fit depends on the anisotropic strength. For any given value of the anisotropic strength, the frequency increases with the increase of the mass of the neutron star, linearly for lower masses, and rapidly at higher masses. However, this non-linear rise in the frequency with the mass is not prominent when the radial pressure is larger than the tangential pressure. For a fixed value of a small mass, higher anisotropy leads to a larger value of the frequency, but when the fixed mass is above a threshold value, higher anisotropy leads to a smaller value of the frequency. The nature of the variation in the frequency with the change in the anisotropic strength is similar for the two equations of state, but for a fixed mass and the same amount of the anisotropy, the softer equations of state gives higher frequency. We also find that the damping time of the f-mode oscillation decreases as the mass of the neutron star increases for all values of the anisotropic strength. For a fixed mass of the neutron star and for the same amount of the anisotropy, the value of the damping time is lower for the softer equation of state, but the nature of the variation in the damping time with the change in the anisotropic strength is similar. |
1508.06221 | Shih-Yuin Lin | Shih-Yuin Lin, Chung-Hsien Chou, Bei-Lok Hu | Entanglement Dynamics of Detectors in an Einstein Cylinder | 32 pages, 13 figures. Early-time analysis and comparison with
perturbative results added; Figs. 6-9, 11-12 updated | JHEP 03 (2016) 047 | 10.1007/JHEP03(2016)047 | null | gr-qc hep-th quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate how nontrivial topology affects the entanglement dynamics
between a detector and a quantum field and between two detectors mediated by a
quantum field. Nontrivial topology refers to both that of the base space and
that of the bundle. Using a derivative-coupling Unruh-DeWitt-like detector
model interacting with a quantum scalar field in an Einstein cylinder S1
(space) x R1 (time), we see the beating behaviors in the dynamics of the
detector-field entanglement and the detector-detector entanglement, which
distinguish from the results in the non-compact (1+1) dimensional Minkowski
space. The beat patterns of entanglement dynamics in a normal and a twisted
field with the same parameter values are different because of the difference in
the spectrum of the field modes. In terms of the kinetic momentum of the
detectors, we find that the contribution by the zero mode in a normal field to
entanglement dynamics has no qualitative difference from those by the nonzero
modes.
| [
{
"created": "Tue, 25 Aug 2015 16:52:05 GMT",
"version": "v1"
},
{
"created": "Wed, 16 Mar 2016 06:00:43 GMT",
"version": "v2"
}
] | 2016-03-17 | [
[
"Lin",
"Shih-Yuin",
""
],
[
"Chou",
"Chung-Hsien",
""
],
[
"Hu",
"Bei-Lok",
""
]
] | We investigate how nontrivial topology affects the entanglement dynamics between a detector and a quantum field and between two detectors mediated by a quantum field. Nontrivial topology refers to both that of the base space and that of the bundle. Using a derivative-coupling Unruh-DeWitt-like detector model interacting with a quantum scalar field in an Einstein cylinder S1 (space) x R1 (time), we see the beating behaviors in the dynamics of the detector-field entanglement and the detector-detector entanglement, which distinguish from the results in the non-compact (1+1) dimensional Minkowski space. The beat patterns of entanglement dynamics in a normal and a twisted field with the same parameter values are different because of the difference in the spectrum of the field modes. In terms of the kinetic momentum of the detectors, we find that the contribution by the zero mode in a normal field to entanglement dynamics has no qualitative difference from those by the nonzero modes. |
gr-qc/9510066 | null | Enrico Carugno, Marco Litterio, Franco Occhionero, and Giuseppe
Pollifrone | Inflation in Multidimensional Quantum Cosmology | RevTeX, 30 pages, 4 figures available via fax on request to
litterio@astrom.astro.it, submitted to Phys. Rev. D | Phys.Rev. D53 (1996) 6863-6874 | 10.1103/PhysRevD.53.6863 | null | gr-qc | null | We extend to multidimensional cosmology Vilenkin's prescription of tunnelling
from nothing for the quantum origin of the observable Universe. Our model
consists of a $D+4$-dimensional spacetime of topology ${\cal R}\times {\cal
S}^3 \times{\cal S}^D$, with a scalar field (``chaotic inflaton'') for the
matter component. Einstein gravity and Casimir compactification are assumed.
The resulting minisuperspace is 3--dimensional. Patchwise we find an
approximate analytic solution of the Wheeler--DeWitt equation through which we
discuss the tunnelling picture and the probability of nucleation of the
classical Universe with compactifying extra dimensions. Our conclusion is that
the most likely initial conditions, although they do not lead to the
compactification of the internal space, still yield (power-law) inflation for
the outer space. The scenario is physically acceptable because the inner space
growth is limited to $\sim 10^{11}$ in 100 e-foldings of inflation, starting
from the Planck scale.
| [
{
"created": "Tue, 31 Oct 1995 13:03:24 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Carugno",
"Enrico",
""
],
[
"Litterio",
"Marco",
""
],
[
"Occhionero",
"Franco",
""
],
[
"Pollifrone",
"Giuseppe",
""
]
] | We extend to multidimensional cosmology Vilenkin's prescription of tunnelling from nothing for the quantum origin of the observable Universe. Our model consists of a $D+4$-dimensional spacetime of topology ${\cal R}\times {\cal S}^3 \times{\cal S}^D$, with a scalar field (``chaotic inflaton'') for the matter component. Einstein gravity and Casimir compactification are assumed. The resulting minisuperspace is 3--dimensional. Patchwise we find an approximate analytic solution of the Wheeler--DeWitt equation through which we discuss the tunnelling picture and the probability of nucleation of the classical Universe with compactifying extra dimensions. Our conclusion is that the most likely initial conditions, although they do not lead to the compactification of the internal space, still yield (power-law) inflation for the outer space. The scenario is physically acceptable because the inner space growth is limited to $\sim 10^{11}$ in 100 e-foldings of inflation, starting from the Planck scale. |
2308.00308 | YuSen An | Xiao Liang, Ya-Peng Hu, Chen-Hao Wu, Yu-Sen An | Thermodynamics and evaporation of perfect fluid dark matter black hole
in phantom background | 14 pages, 2 figures, comments are welcomed. v2: typos corrected | null | 10.1140/epjc/s10052-023-12200-8 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a novel interpretation of the thermodynamics of perfect fluid dark
matter (PFDM) black hole based on Misner-Sharp energy, and then investigate its
evaporation behavior. We find that the ratio between dark sector initial
density and black hole horizon radius significantly influences black hole
evaporation behaviors. We demonstrate that the presence of the dark sector can
significantly extend the lifetime of a black hole which is similar to the
Reissner-Nordstrom case. Our work reformulates the thermodynamics of PFDM black
holes and points out the existence of long-lived black holes in the presence of
the dark sector.
| [
{
"created": "Tue, 1 Aug 2023 05:59:03 GMT",
"version": "v1"
},
{
"created": "Tue, 8 Aug 2023 03:04:52 GMT",
"version": "v2"
}
] | 2023-11-09 | [
[
"Liang",
"Xiao",
""
],
[
"Hu",
"Ya-Peng",
""
],
[
"Wu",
"Chen-Hao",
""
],
[
"An",
"Yu-Sen",
""
]
] | We present a novel interpretation of the thermodynamics of perfect fluid dark matter (PFDM) black hole based on Misner-Sharp energy, and then investigate its evaporation behavior. We find that the ratio between dark sector initial density and black hole horizon radius significantly influences black hole evaporation behaviors. We demonstrate that the presence of the dark sector can significantly extend the lifetime of a black hole which is similar to the Reissner-Nordstrom case. Our work reformulates the thermodynamics of PFDM black holes and points out the existence of long-lived black holes in the presence of the dark sector. |
1705.03654 | Bobir Toshmatov | Bobir Toshmatov, Cosimo Bambi, Bobomurat Ahmedov, Zden\v{e}k
Stuchl\'ik, Jan Schee | Scalar perturbations of nonsingular nonrotating black holes in conformal
gravity | 10 pages, 5 figures, 3 tables | Phys. Rev. D 96, 064028 (2017) | 10.1103/PhysRevD.96.064028 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study scalar and electromagnetic perturbations of a family of nonsingular
nonrotating black hole spacetimes that are solutions in a large class of
conformally invariant theories of gravity. The effective potential for scalar
perturbations depends on the exact form of the scaling factor. Electromagnetic
perturbations do not feel the scaling factor, and the corresponding quasinormal
mode spectrum is the same as in the Schwarzschild metric. We find that these
black hole metrics are stable under scalar and electromagnetic perturbations.
Assuming that the quasinormal mode spectrum for scalar perturbations is not too
different from that for gravitational perturbations, we can expect that the
calculation of the quasinormal mode spectrum and the observation with
gravitational wave detectors of quasinormal modes from astrophysical black
holes can constrain the scaling factor and test these solutions.
| [
{
"created": "Wed, 10 May 2017 08:18:50 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Sep 2017 05:32:30 GMT",
"version": "v2"
},
{
"created": "Thu, 21 Sep 2017 09:32:54 GMT",
"version": "v3"
}
] | 2017-09-22 | [
[
"Toshmatov",
"Bobir",
""
],
[
"Bambi",
"Cosimo",
""
],
[
"Ahmedov",
"Bobomurat",
""
],
[
"Stuchlík",
"Zdeněk",
""
],
[
"Schee",
"Jan",
""
]
] | We study scalar and electromagnetic perturbations of a family of nonsingular nonrotating black hole spacetimes that are solutions in a large class of conformally invariant theories of gravity. The effective potential for scalar perturbations depends on the exact form of the scaling factor. Electromagnetic perturbations do not feel the scaling factor, and the corresponding quasinormal mode spectrum is the same as in the Schwarzschild metric. We find that these black hole metrics are stable under scalar and electromagnetic perturbations. Assuming that the quasinormal mode spectrum for scalar perturbations is not too different from that for gravitational perturbations, we can expect that the calculation of the quasinormal mode spectrum and the observation with gravitational wave detectors of quasinormal modes from astrophysical black holes can constrain the scaling factor and test these solutions. |
0904.3263 | Ettore Minguzzi | E. Minguzzi | In a distinguishing spacetime the horismos relation generates the causal
relation | 7 pages, Latex2e | Class.Quant.Grav.26:165005,2009 | 10.1088/0264-9381/26/16/165005 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is proved that in a distinguishing spacetime the horismos relation
E^+=J^+\I^+ generates the causal relation J^+. In other words two causally
related events are joined by a chain of horismotically related events, or
again, the causal relation is the smallest transitive relation containing the
horismos relation. The result is sharp in the sense that distinction can not be
weakened to future or past distinction. Finally, it is proved that a spacetime
in which the horismos relation generates the causal relation is necessarily
non-total imprisoning.
| [
{
"created": "Tue, 21 Apr 2009 14:44:10 GMT",
"version": "v1"
}
] | 2011-06-24 | [
[
"Minguzzi",
"E.",
""
]
] | It is proved that in a distinguishing spacetime the horismos relation E^+=J^+\I^+ generates the causal relation J^+. In other words two causally related events are joined by a chain of horismotically related events, or again, the causal relation is the smallest transitive relation containing the horismos relation. The result is sharp in the sense that distinction can not be weakened to future or past distinction. Finally, it is proved that a spacetime in which the horismos relation generates the causal relation is necessarily non-total imprisoning. |
0801.0834 | Lorenzo Iorio | Lorenzo Iorio | Determination of tidal distortion in the eclipsing binary system V621
Cen by means of deviations from the third Kepler law | Latex, 6 pages, no figures, 1 table. To appear in New Astronomy | NewAstron.13:473-475,2008 | 10.1016/j.newast.2008.01.004 | null | gr-qc astro-ph | null | In this paper we determine the tidal distortion parameter k_m of the
secondary partner (mass loser) of the semi-detached eclipsing binary system
V621 Cen by comparing the phenomenologically determined orbital period
P_b=3.683549(11) d to the Keplerian one P^Kep computed with the values of the
relevant system's parameters determined independently of the third Kepler law
itself. Our result is k_m = -1.5 +/- 0.6. Using the periastron precession, as
traditionally done with other eclipsing binaries in eccentric orbits, would
have not been possible because of the circularity of the V621 Cen path.
| [
{
"created": "Sun, 6 Jan 2008 01:59:15 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Iorio",
"Lorenzo",
""
]
] | In this paper we determine the tidal distortion parameter k_m of the secondary partner (mass loser) of the semi-detached eclipsing binary system V621 Cen by comparing the phenomenologically determined orbital period P_b=3.683549(11) d to the Keplerian one P^Kep computed with the values of the relevant system's parameters determined independently of the third Kepler law itself. Our result is k_m = -1.5 +/- 0.6. Using the periastron precession, as traditionally done with other eclipsing binaries in eccentric orbits, would have not been possible because of the circularity of the V621 Cen path. |
gr-qc/0510071 | Jeferson Oliveira de | Jeferson de Oliveira, Carlos Eduardo Pellicer de Oliveira | Solutions for Klein-Gordon equation in Randall-Sundrum-Kerr scenario | 2 pages, revtex4, contribution to conference "100 years of
Relativity", Sao Paulo, Brazil, Aug. 22-24, 2005 | Braz.J.Phys. 35 (2005) 1127-1128 | null | null | gr-qc | null | We study the scalar perturbations of rotating black holes in framework of
extra dimensions type Randall-Sundrum(RS).
| [
{
"created": "Sat, 15 Oct 2005 15:10:54 GMT",
"version": "v1"
},
{
"created": "Tue, 18 Oct 2005 19:53:39 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"de Oliveira",
"Jeferson",
""
],
[
"de Oliveira",
"Carlos Eduardo Pellicer",
""
]
] | We study the scalar perturbations of rotating black holes in framework of extra dimensions type Randall-Sundrum(RS). |
1912.12540 | Mehran Kamarpour | Mehran Kamarpour | Magnetogenesis in Higgs inflation | 12 pages,6 figures | General Relativity and Gravitation-Revised version published in 14
May 2021 | 10.1007/s10714-021-02824-0 | 53 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the generation of magnetic fields in the Higgs inflation model with
the axial coupling in order to break the conformal invariance of the Maxwell
action and produce strong magnetic fields. We consider radiatively corrected
Higgs inflation potential. In comparison to the Starobinsky potential, we
obtain an extra term as a one loop correction and determine the spectrum of
generalized electromagnetic fields. For two values of coupling parameter
$\chi_{1}=5\times 10^{9}$ and $\chi_{1}=7.5\times 10^{9}$, the back-reaction is
weak and our analysis is self-consistent.
| [
{
"created": "Sat, 28 Dec 2019 23:06:31 GMT",
"version": "v1"
}
] | 2021-08-17 | [
[
"Kamarpour",
"Mehran",
""
]
] | We study the generation of magnetic fields in the Higgs inflation model with the axial coupling in order to break the conformal invariance of the Maxwell action and produce strong magnetic fields. We consider radiatively corrected Higgs inflation potential. In comparison to the Starobinsky potential, we obtain an extra term as a one loop correction and determine the spectrum of generalized electromagnetic fields. For two values of coupling parameter $\chi_{1}=5\times 10^{9}$ and $\chi_{1}=7.5\times 10^{9}$, the back-reaction is weak and our analysis is self-consistent. |
gr-qc/0309014 | Wladimir Belayev | D. Yu. Tsipenyuk and W. B. Belayev | Explanation of the anomalous acceleration of a free moving body in the
frame of extended space model | null | null | null | null | gr-qc astro-ph | null | We consider (1+4) generalization of classical electrodynamics including
gravitation field. With this approach it is assumed a presence of an extra
component of extended field stress tensor, whose physical interpretation is
based on necessity to obtain Newton gravity law as particular case. In model
analyzed in present work mass of having in 4D a rest mass particle moves in
five-dimensional space-time along fifth coordinate with light velocity and its
electric charge is a stationary value in additional dimension. Generalized
gravity law that is obtained from extended Maxwell equations confirmed by
existence of variable component of Pioneer 10 additional acceleration, whose
analyze is made in frame of this model.
| [
{
"created": "Wed, 3 Sep 2003 13:16:29 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Tsipenyuk",
"D. Yu.",
""
],
[
"Belayev",
"W. B.",
""
]
] | We consider (1+4) generalization of classical electrodynamics including gravitation field. With this approach it is assumed a presence of an extra component of extended field stress tensor, whose physical interpretation is based on necessity to obtain Newton gravity law as particular case. In model analyzed in present work mass of having in 4D a rest mass particle moves in five-dimensional space-time along fifth coordinate with light velocity and its electric charge is a stationary value in additional dimension. Generalized gravity law that is obtained from extended Maxwell equations confirmed by existence of variable component of Pioneer 10 additional acceleration, whose analyze is made in frame of this model. |
gr-qc/0104006 | J. B. Moortgat | Joachim Moortgat | Watching Gravitational Waves | Supervisors: Gerard 't Hooft and Jan Kuijpers | null | null | null | gr-qc | null | In the vicinity of merging neutron strar binaries or supernova remnants,
gravitational waves can interact with the prevailing strong magnetic fields.
The resulting partial conversion of gravitational waves into electromagnetic
(radio) waves might prove to be an indirect way of detecting gravitational
waves from such sources.
Another interesting interaction considered in this article is the excitation
of magnetosonic plasma waves by a gravitational wave passing through the
surrounding plasma. The transfer of gravitational wave energy into the plasma
might help to fuel the `fireball' of electromagnetic radiation observed in
gamma ray bursts. In the last section of the article, a dispersion relation is
derived for such magnetosonic plasma waves driven by a gravitational wave.
| [
{
"created": "Mon, 2 Apr 2001 14:23:21 GMT",
"version": "v1"
},
{
"created": "Wed, 4 Apr 2001 12:26:20 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Moortgat",
"Joachim",
""
]
] | In the vicinity of merging neutron strar binaries or supernova remnants, gravitational waves can interact with the prevailing strong magnetic fields. The resulting partial conversion of gravitational waves into electromagnetic (radio) waves might prove to be an indirect way of detecting gravitational waves from such sources. Another interesting interaction considered in this article is the excitation of magnetosonic plasma waves by a gravitational wave passing through the surrounding plasma. The transfer of gravitational wave energy into the plasma might help to fuel the `fireball' of electromagnetic radiation observed in gamma ray bursts. In the last section of the article, a dispersion relation is derived for such magnetosonic plasma waves driven by a gravitational wave. |
0711.2469 | Barry Wardell | Adrian C. Ottewill and Barry Wardell | Quasi-local contribution to the scalar self-force: Geodesic Motion | Final Phys. Rev. D version. 24 pages, revtex4. Minor typos corrected | Phys.Rev.D77:104002,2008 | 10.1103/PhysRevD.77.104002 | null | gr-qc | null | We consider a scalar charge travelling in a curved background spacetime. We
calculate the quasi-local contribution to the scalar self-force experienced by
such a particle following a geodesic in a general spacetime. We also show that
if we assume a massless field and a vacuum background spacetime, the expression
for the self-force simplifies significantly. We consider some specific cases
whose gravitational analog are of immediate physical interest for the
calculation of radiation reaction corrected orbits of binary black hole
systems. These systems are expected to be detectable by the LISA space based
gravitational wave observatory. We also investigate how alternate techniques
may be employed in some specific cases and use these as a check on our own
results.
| [
{
"created": "Thu, 15 Nov 2007 17:33:55 GMT",
"version": "v1"
},
{
"created": "Tue, 29 Jan 2008 14:38:53 GMT",
"version": "v2"
},
{
"created": "Mon, 5 May 2008 17:04:33 GMT",
"version": "v3"
}
] | 2008-11-26 | [
[
"Ottewill",
"Adrian C.",
""
],
[
"Wardell",
"Barry",
""
]
] | We consider a scalar charge travelling in a curved background spacetime. We calculate the quasi-local contribution to the scalar self-force experienced by such a particle following a geodesic in a general spacetime. We also show that if we assume a massless field and a vacuum background spacetime, the expression for the self-force simplifies significantly. We consider some specific cases whose gravitational analog are of immediate physical interest for the calculation of radiation reaction corrected orbits of binary black hole systems. These systems are expected to be detectable by the LISA space based gravitational wave observatory. We also investigate how alternate techniques may be employed in some specific cases and use these as a check on our own results. |
2206.03407 | F. S. Guzman | Francisco S. Guzman | Possible formation mechanism of multistate gravitational atoms | 6 pages, 8 figures, matches the accepted version | Phys. Rev. D 105, 123535 (2022) | 10.1103/PhysRevD.105.123535 | null | gr-qc astro-ph.GA | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The collision of two equilibrium ground state solutions of the
Schr\"odinger-Poisson (SP) system, in orthogonal states, is proposed as a
formation mechanism of mixed state solutions of the SP system with spherical
and first dipolar components. The collisions are simulated by solving
numerically the SP system for two orthogonal states, considering head-on
encounters, and using various mass ratios between the initial configurations
with different head-on momentum. The results indicate that the less massive of
the configurations pinches-off the more massive one, and redistributes its
density along the axis of collision. The averaged in time density of the two
states resembles the distribution of matter of bi-state equilibrium
configurations with monopolar and dipolar contributions.
| [
{
"created": "Tue, 7 Jun 2022 15:56:52 GMT",
"version": "v1"
},
{
"created": "Thu, 30 Jun 2022 03:20:27 GMT",
"version": "v2"
}
] | 2022-07-01 | [
[
"Guzman",
"Francisco S.",
""
]
] | The collision of two equilibrium ground state solutions of the Schr\"odinger-Poisson (SP) system, in orthogonal states, is proposed as a formation mechanism of mixed state solutions of the SP system with spherical and first dipolar components. The collisions are simulated by solving numerically the SP system for two orthogonal states, considering head-on encounters, and using various mass ratios between the initial configurations with different head-on momentum. The results indicate that the less massive of the configurations pinches-off the more massive one, and redistributes its density along the axis of collision. The averaged in time density of the two states resembles the distribution of matter of bi-state equilibrium configurations with monopolar and dipolar contributions. |
1311.0420 | Michalis Agathos | Michalis Agathos, Walter Del Pozzo, Tjonnie G.F. Li, Chris Van Den
Broeck, John Veitch, Salvatore Vitale | TIGER: A data analysis pipeline for testing the strong-field dynamics of
general relativity with gravitational wave signals from coalescing compact
binaries | 12 pages, 9 figures. Version as appears in Phys. Rev. D | Phys. Rev. D 89, 082001 (2014) | 10.1103/PhysRevD.89.082001 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The direct detection of gravitational waves with upcoming second-generation
gravitational wave detectors such as Advanced LIGO and Virgo will allow us to
probe the genuinely strong-field dynamics of general relativity (GR) for the
first time. We present a data analysis pipeline called TIGER (Test
Infrastructure for GEneral Relativity), which is designed to utilize detections
of compact binary coalescences to test GR in this regime. TIGER is a
model-independent test of GR itself, in that it is not necessary to compare
with any specific alternative theory. It performs Bayesian inference on two
hypotheses: the GR hypothesis $\mathcal{H}_{\rm GR}$, and $\mathcal{H}_{\rm
modGR}$, which states that one or more of the post-Newtonian coefficients in
the waveform are not as predicted by GR. By the use of multiple sub-hypotheses
of $\mathcal{H}_{\rm modGR}$, in each of which a different number of
parameterized deformations of the GR phase are allowed, an arbitrarily large
number of 'testing parameters' can be used without having to worry about a
model being insufficiently parsimonious if the true number of extra parameters
is in fact small. TIGER is well-suited to the regime where most sources have
low signal-to-noise ratios, again through the use of these sub-hypotheses.
Information from multiple sources can trivially be combined, leading to a
stronger test. We focus on binary neutron star coalescences, for which
sufficiently accurate waveform models are available that can be generated fast
enough on a computer to be fit for use in Bayesian inference. We show that the
pipeline is robust against a number of fundamental, astrophysical, and
instrumental effects, such as differences between waveform approximants, a
limited number of post-Newtonian phase contributions being known, the effects
of neutron star spins and tidal deformability on the orbital motion, and
instrumental calibration errors.
| [
{
"created": "Sun, 3 Nov 2013 01:06:15 GMT",
"version": "v1"
},
{
"created": "Fri, 6 Jun 2014 22:12:17 GMT",
"version": "v2"
}
] | 2014-06-10 | [
[
"Agathos",
"Michalis",
""
],
[
"Del Pozzo",
"Walter",
""
],
[
"Li",
"Tjonnie G. F.",
""
],
[
"Broeck",
"Chris Van Den",
""
],
[
"Veitch",
"John",
""
],
[
"Vitale",
"Salvatore",
""
]
] | The direct detection of gravitational waves with upcoming second-generation gravitational wave detectors such as Advanced LIGO and Virgo will allow us to probe the genuinely strong-field dynamics of general relativity (GR) for the first time. We present a data analysis pipeline called TIGER (Test Infrastructure for GEneral Relativity), which is designed to utilize detections of compact binary coalescences to test GR in this regime. TIGER is a model-independent test of GR itself, in that it is not necessary to compare with any specific alternative theory. It performs Bayesian inference on two hypotheses: the GR hypothesis $\mathcal{H}_{\rm GR}$, and $\mathcal{H}_{\rm modGR}$, which states that one or more of the post-Newtonian coefficients in the waveform are not as predicted by GR. By the use of multiple sub-hypotheses of $\mathcal{H}_{\rm modGR}$, in each of which a different number of parameterized deformations of the GR phase are allowed, an arbitrarily large number of 'testing parameters' can be used without having to worry about a model being insufficiently parsimonious if the true number of extra parameters is in fact small. TIGER is well-suited to the regime where most sources have low signal-to-noise ratios, again through the use of these sub-hypotheses. Information from multiple sources can trivially be combined, leading to a stronger test. We focus on binary neutron star coalescences, for which sufficiently accurate waveform models are available that can be generated fast enough on a computer to be fit for use in Bayesian inference. We show that the pipeline is robust against a number of fundamental, astrophysical, and instrumental effects, such as differences between waveform approximants, a limited number of post-Newtonian phase contributions being known, the effects of neutron star spins and tidal deformability on the orbital motion, and instrumental calibration errors. |
1403.3701 | Sergio Giardino | Sergio Giardino | Axisymmmetric empty space: light propagation, orbits and dark matter | null | Journal of Modern Physics, 2014, 5, 1402-1411 | 10.4236/jmp.2014.515141 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This study presents a axisymmetric solution of the Einstein equations for
empty space. The geometry is studied by determining its Petrov classification
and Killing vectors. Light propagation, orbital motion and asymptotic and
Newtonian limits are also studied. Additionally, cosmological applications of
the geometry as an alternative model for the inflationary universe and as a
substitute for dark matter and quintessence are also outlined.
| [
{
"created": "Fri, 14 Mar 2014 20:14:08 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Sep 2014 22:39:10 GMT",
"version": "v2"
}
] | 2014-09-22 | [
[
"Giardino",
"Sergio",
""
]
] | This study presents a axisymmetric solution of the Einstein equations for empty space. The geometry is studied by determining its Petrov classification and Killing vectors. Light propagation, orbital motion and asymptotic and Newtonian limits are also studied. Additionally, cosmological applications of the geometry as an alternative model for the inflationary universe and as a substitute for dark matter and quintessence are also outlined. |
gr-qc/0012005 | Palma Guillermo | G. Palma and V.H. Cardenas (USACH) | Resonance enhancement of particle production during reheating | 4 pages, 4 figures(eps), using RevTex | Class.Quant.Grav. 18 (2001) 2233 | 10.1088/0264-9381/18/11/316 | null | gr-qc hep-ph | null | We found a consistent equation of reheating after inflation, which shows that
for small quantum fluctuations the frequencies of resonance are slighted
different from the standard ones. Quantum interference is taken into account
and we found that at large fluctuations the process mimics very well the usual
parametric resonance but proceed in a different dynamical way. The analysis is
made in a toy quantum mechanical model and we discuss further its extension to
quantum field theory.
| [
{
"created": "Fri, 1 Dec 2000 18:27:53 GMT",
"version": "v1"
},
{
"created": "Wed, 11 Apr 2001 22:18:00 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Palma",
"G.",
"",
"USACH"
],
[
"Cardenas",
"V. H.",
"",
"USACH"
]
] | We found a consistent equation of reheating after inflation, which shows that for small quantum fluctuations the frequencies of resonance are slighted different from the standard ones. Quantum interference is taken into account and we found that at large fluctuations the process mimics very well the usual parametric resonance but proceed in a different dynamical way. The analysis is made in a toy quantum mechanical model and we discuss further its extension to quantum field theory. |
gr-qc/0403109 | Jerzy Matyjasek | Jerzy Matyjasek | Extremal limit of the regular charged black holes in nonlinear
electrodynamics | null | Phys.Rev. D70 (2004) 047504 | 10.1103/PhysRevD.70.047504 | null | gr-qc | null | The near horizon limit of the extreme nonlinear black hole is investigated.
It is shown that resulting geometry belongs to the AdS2xS2 class with different
modules of curvatures of subspaces and could be described in terms of the
Lambert functions. It is demonstrated that the considered class of Lagrangians
does not admit solutions of the Bertotti-Robinson type.
| [
{
"created": "Sun, 28 Mar 2004 19:24:31 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Matyjasek",
"Jerzy",
""
]
] | The near horizon limit of the extreme nonlinear black hole is investigated. It is shown that resulting geometry belongs to the AdS2xS2 class with different modules of curvatures of subspaces and could be described in terms of the Lambert functions. It is demonstrated that the considered class of Lagrangians does not admit solutions of the Bertotti-Robinson type. |
gr-qc/0603101 | Jose' P. S. Lemos | Jose' P. S. Lemos, Vilson T. Zanchin | Gravitational magnetic monopoles and Majumdar-Papapetrou stars | 38 pages,9 Figures, minor changes | J.Math.Phys. 47 (2006) 042504 | 10.1063/1.2184766 | null | gr-qc astro-ph hep-th | null | A large amount of work has been dedicated to studying general relativity
coupled to non-Abelian Yang-Mills type theories. It has been shown that the
magnetic monopole, a solution of the Yang-Mills-Higgs equations can be coupled
to gravitation. For a low Higgs mass there are regular solutions, and for a
sufficiently massive monopole the system develops an extremal magnetic
Reissner-Nordstrom quasi-horizon. These solutions, called quasi-black holes,
although non-singular, are arbitrarily close to having a horizon. However, at
the critical value the quasi-black hole turns into a degenerate spacetime. On
the other hand, for a high Higgs mass, a sufficiently massive monopole develops
also a quasi-black hole, but it turns into an extremal true horizon, with
matter fields outside. One can also put a small Schwarzschild black hole inside
the magnetic monopole, an example of a non-Abelian black hole. Surprisingly,
Majumdar-Papapetrou systems, Abelian systems constructed from extremal dust,
also show a resembling behavior. Previously, we have reported that one can find
Majumdar-Papapetrou solutions which can be arbitrarily close of being a black
hole, displaying quasi-black hole behavior. With the aim of better
understanding the similarities between gravitational monopoles and
Majumdar-Papapetrou systems, we study a system composed of two extremal
electrically charged spherical shells (or stars, generically) in the
Einstein--Maxwell--Majumdar-Papapetrou theory. We review the gravitational
properties of the monopoles, and compare with the properties of the double
extremal electric shell system. These quasi-black holes can help in the
understanding of true black holes, and can give insight into the nature of the
entropy of black holes in the form of entanglement.
| [
{
"created": "Sat, 25 Mar 2006 19:32:12 GMT",
"version": "v1"
},
{
"created": "Sat, 1 Apr 2006 18:46:56 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Lemos",
"Jose' P. S.",
""
],
[
"Zanchin",
"Vilson T.",
""
]
] | A large amount of work has been dedicated to studying general relativity coupled to non-Abelian Yang-Mills type theories. It has been shown that the magnetic monopole, a solution of the Yang-Mills-Higgs equations can be coupled to gravitation. For a low Higgs mass there are regular solutions, and for a sufficiently massive monopole the system develops an extremal magnetic Reissner-Nordstrom quasi-horizon. These solutions, called quasi-black holes, although non-singular, are arbitrarily close to having a horizon. However, at the critical value the quasi-black hole turns into a degenerate spacetime. On the other hand, for a high Higgs mass, a sufficiently massive monopole develops also a quasi-black hole, but it turns into an extremal true horizon, with matter fields outside. One can also put a small Schwarzschild black hole inside the magnetic monopole, an example of a non-Abelian black hole. Surprisingly, Majumdar-Papapetrou systems, Abelian systems constructed from extremal dust, also show a resembling behavior. Previously, we have reported that one can find Majumdar-Papapetrou solutions which can be arbitrarily close of being a black hole, displaying quasi-black hole behavior. With the aim of better understanding the similarities between gravitational monopoles and Majumdar-Papapetrou systems, we study a system composed of two extremal electrically charged spherical shells (or stars, generically) in the Einstein--Maxwell--Majumdar-Papapetrou theory. We review the gravitational properties of the monopoles, and compare with the properties of the double extremal electric shell system. These quasi-black holes can help in the understanding of true black holes, and can give insight into the nature of the entropy of black holes in the form of entanglement. |
1807.08313 | Adriano Vigan\`o | Matteo Broccoli and Adriano Vigan\`o | Electromagnetic self-force in curved spacetime: New insights from the
Janis-Newman algorithm | 4 pages. Minor corrections, added references. Version accepted by
Physical Review D | Phys. Rev. D 98, 084007 (2018) | 10.1103/PhysRevD.98.084007 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present an original approach to compute the electromagnetic self-force
acting on a static charge in Kerr spacetime. Our approach is based on an
improved version of the Janis-Newman algorithm and extends its range of
applicability. It leads to a closed expression which generalizes the existing
one and, since it does not involve the electromagnetic potential, it simplifies
the calculation of the self-force.
| [
{
"created": "Sun, 22 Jul 2018 16:34:12 GMT",
"version": "v1"
},
{
"created": "Fri, 27 Jul 2018 13:44:37 GMT",
"version": "v2"
},
{
"created": "Mon, 8 Oct 2018 13:10:19 GMT",
"version": "v3"
}
] | 2018-10-10 | [
[
"Broccoli",
"Matteo",
""
],
[
"Viganò",
"Adriano",
""
]
] | We present an original approach to compute the electromagnetic self-force acting on a static charge in Kerr spacetime. Our approach is based on an improved version of the Janis-Newman algorithm and extends its range of applicability. It leads to a closed expression which generalizes the existing one and, since it does not involve the electromagnetic potential, it simplifies the calculation of the self-force. |
2303.08002 | Hristu Culetu | Hristu Culetu | A regular version of the extremal RN spacetime | 10 pages, no figures, accepted by Phys. Lett. B 839C (2023) 137775 | null | 10.1016/j.physletb.2023.137775 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A modified extremal Reissner-Nordstrom geometry, void of singularities, is
proposed in this work, by means of an exponential factor depending on a
positive constant $k$. All the metric coefficients are positive and finite and
the spacetime has no any horizon. The curvature invariants are regular at the
origin of coordinates and at infinity. The energy conditions for the stress
tensor associate to the imperfect fluid are investigated. The gravitational
field presents repulsive properties near the gravitational radius associated to
the mass $m$. With the choice $k = 1/m$, the Komar energy $W_{K}$ of the mass
$m$ changes its sign at $r = \lambda$ ($\lambda$ is the Compton wavelength of
$m$), when the classical energy $mc^{2}$ equals the energy $\hbar c/r$.
| [
{
"created": "Sun, 12 Mar 2023 20:48:57 GMT",
"version": "v1"
}
] | 2023-03-15 | [
[
"Culetu",
"Hristu",
""
]
] | A modified extremal Reissner-Nordstrom geometry, void of singularities, is proposed in this work, by means of an exponential factor depending on a positive constant $k$. All the metric coefficients are positive and finite and the spacetime has no any horizon. The curvature invariants are regular at the origin of coordinates and at infinity. The energy conditions for the stress tensor associate to the imperfect fluid are investigated. The gravitational field presents repulsive properties near the gravitational radius associated to the mass $m$. With the choice $k = 1/m$, the Komar energy $W_{K}$ of the mass $m$ changes its sign at $r = \lambda$ ($\lambda$ is the Compton wavelength of $m$), when the classical energy $mc^{2}$ equals the energy $\hbar c/r$. |
1201.1255 | Anna McCoy | A. E. McCoy | Gamma Ray Bursts, The Principle of Relative Locality and Connection
Normal Coordinates | 20 pages, 1 figure. Essay submitted as partial fulfillment of the
requirements for the degree of masters of science, University of
Waterloo/Perimeter Institute of Theoretical Physics. arXiv admin note: text
overlap with arXiv:1103.5626 by other authors | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The launch of the Fermi telescope in 2008 opened up the possibility of
measuring the energy dependence of the speed of light by considering the time
delay in the arrival of gamma ray bursts emitted simultaneously from very
distant sources.The expected time delay between the arrival of gamma rays of
significantly different energies as predicted by the framework of relative
locality has already been calculated in Riemann normal coordinates. In the
following, we calculate the time delay in more generality and then specialize
to the connection normal coordinate system as a check that the results are
coordinate independent. We also show that this result does not depend on the
presence of torsion.
| [
{
"created": "Wed, 4 Jan 2012 03:45:21 GMT",
"version": "v1"
}
] | 2012-01-06 | [
[
"McCoy",
"A. E.",
""
]
] | The launch of the Fermi telescope in 2008 opened up the possibility of measuring the energy dependence of the speed of light by considering the time delay in the arrival of gamma ray bursts emitted simultaneously from very distant sources.The expected time delay between the arrival of gamma rays of significantly different energies as predicted by the framework of relative locality has already been calculated in Riemann normal coordinates. In the following, we calculate the time delay in more generality and then specialize to the connection normal coordinate system as a check that the results are coordinate independent. We also show that this result does not depend on the presence of torsion. |
1106.2241 | Michael Hohensee | Michael A. Hohensee and Holger Mueller | Precision tests of General Relativity with Matter Waves | Conference Proceedings for talk given in January, 2011 at the Winter
Colloquium on the Physics of Quantum Electronics. Submitted to the Journal of
Modern Optics | J. Mod. Opt., v58, 2021-2027, 2011 | 10.1080/09500340.2011.606376 | null | gr-qc hep-ph quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We review the physics of atoms and clocks in weakly curved spacetime, and how
each may be used to test the Einstein Equivalence Principle (EEP) in the
context of the minimal Standard Model Extension (mSME). We find that
conventional clocks and matter-wave interferometers are sensitive to the same
kinds of EEP-violating physics. We show that the analogy between matter-waves
and clocks remains true for systems beyond the semiclassical limit. We
quantitatively compare the experimentally observable signals for EEP violation
in matter-wave experiments. We find that comparisons of $^{6}$Li and $^{7}$Li
are particularly sensitive to such anomalies. Tests involving unstable
isotopes, for which matter-wave interferometers are well suited, may further
improve the sensitivity of EEP tests.
| [
{
"created": "Sat, 11 Jun 2011 14:24:33 GMT",
"version": "v1"
}
] | 2012-02-24 | [
[
"Hohensee",
"Michael A.",
""
],
[
"Mueller",
"Holger",
""
]
] | We review the physics of atoms and clocks in weakly curved spacetime, and how each may be used to test the Einstein Equivalence Principle (EEP) in the context of the minimal Standard Model Extension (mSME). We find that conventional clocks and matter-wave interferometers are sensitive to the same kinds of EEP-violating physics. We show that the analogy between matter-waves and clocks remains true for systems beyond the semiclassical limit. We quantitatively compare the experimentally observable signals for EEP violation in matter-wave experiments. We find that comparisons of $^{6}$Li and $^{7}$Li are particularly sensitive to such anomalies. Tests involving unstable isotopes, for which matter-wave interferometers are well suited, may further improve the sensitivity of EEP tests. |
gr-qc/0703125 | Willians Barreto | L. Herrera, W. Barreto, J. Carot and A. Di Prisco | Why does gravitational radiation produce vorticity? | 9 pages; to appear in Classical and Quantum Gravity | Class.Quant.Grav.24:2645-2651,2007 | 10.1088/0264-9381/24/10/010 | null | gr-qc | null | We calculate the vorticity of world--lines of observers at rest in a
Bondi--Sachs frame, produced by gravitational radiation, in a general Sachs
metric. We claim that such an effect is related to the super--Poynting vector,
in a similar way as the existence of the electromagnetic Poynting vector is
related to the vorticity in stationary electrovacum spacetimes.
| [
{
"created": "Mon, 26 Mar 2007 15:17:26 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Herrera",
"L.",
""
],
[
"Barreto",
"W.",
""
],
[
"Carot",
"J.",
""
],
[
"Di Prisco",
"A.",
""
]
] | We calculate the vorticity of world--lines of observers at rest in a Bondi--Sachs frame, produced by gravitational radiation, in a general Sachs metric. We claim that such an effect is related to the super--Poynting vector, in a similar way as the existence of the electromagnetic Poynting vector is related to the vorticity in stationary electrovacum spacetimes. |
2108.10040 | J\"urgen Struckmeier | J. Struckmeier, A. van de Venn, and D. Vasak | Identity for scalar-valued functions of tensors and its applications to
energy-momentum tensors in classical field theories and gravity | 11 pages | Astron. Nachr. / AN. 2022;e20220074 | 10.1002/asna.20220074 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We prove a theorem on scalar-valued functions of tensors, where ``scalar''
refers to absolute scalars as well as relative scalars of weight $w$. The
present work thereby generalizes an identity referred to earlier by Rosenfeld
in his publication ``On the energy-momentum tensor''. The theorem provides a
$(1,1)$-tensor identity which can be regarded as the tensor analogue of the
identity following from Euler's theorem on homogeneous functions. The
remarkably simple identity is independent of any internal symmetries of the
constituent tensors, providing a powerful tool for deriving relations between
field-theoretical expressions and physical quantities. We apply the identity
especially for analyzing the metric and canonical energy-momentum tensors of
matter and gravity and the relation between them. Moreover, we present a
generalized Einstein field equation for arbitrary version of vacuum space-time
dynamics -- including torsion and non-metricity. The identity allows to
formulate an equivalent representation of this equation. Thereby the conjecture
of a zero-energy universe is confirmed.
| [
{
"created": "Mon, 23 Aug 2021 10:11:48 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Sep 2021 14:01:15 GMT",
"version": "v2"
},
{
"created": "Tue, 6 Sep 2022 11:02:30 GMT",
"version": "v3"
},
{
"created": "Sat, 12 Nov 2022 17:34:25 GMT",
"version": "v4"
}
] | 2022-11-15 | [
[
"Struckmeier",
"J.",
""
],
[
"van de Venn",
"A.",
""
],
[
"Vasak",
"D.",
""
]
] | We prove a theorem on scalar-valued functions of tensors, where ``scalar'' refers to absolute scalars as well as relative scalars of weight $w$. The present work thereby generalizes an identity referred to earlier by Rosenfeld in his publication ``On the energy-momentum tensor''. The theorem provides a $(1,1)$-tensor identity which can be regarded as the tensor analogue of the identity following from Euler's theorem on homogeneous functions. The remarkably simple identity is independent of any internal symmetries of the constituent tensors, providing a powerful tool for deriving relations between field-theoretical expressions and physical quantities. We apply the identity especially for analyzing the metric and canonical energy-momentum tensors of matter and gravity and the relation between them. Moreover, we present a generalized Einstein field equation for arbitrary version of vacuum space-time dynamics -- including torsion and non-metricity. The identity allows to formulate an equivalent representation of this equation. Thereby the conjecture of a zero-energy universe is confirmed. |
1203.1844 | Pedro Castelo Ferreira Dr. | P. Castelo Ferreira | Planetary motion on an expanding locally anisotropic background | 27 pages, 3 figures, 4 tables v2: published version, measurement
standard is fixed over time (dAU/dt = 0, dG/dt \neq 0) v1: unpublished
version, measurement standard is varying over time (dAU/dt \neq 0, dG/dt = 0) | Acta. Appl. Math. 131 (2014) 155-177 | 10.1007/s10440-013-9852-1 | null | gr-qc astro-ph.SR hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work are computed analytical solutions for orbital motion on a
background described by an Expanding Locally Anisotropic (ELA) metric ansatz.
This metric interpolates between the Schwarzschild metric near the central mass
and the Robertson-Walker metric describing the expanding cosmological
background far from the central mass allowing for a fine-tuneable covariant
parameterization of gravitational interactions corrections in between these two
asymptotic limits. In particular it is shown that the decrease of the Sun's
mass by radiation emission plus the General Relativity corrections due to the
ELA metric background with respect to Schwarzschild backgrounds can be mapped
to the reported yearly variation of the gravitational constant $\dot{G}$
through Kepler's third law. Based on the value of the heuristic fit
corresponding to the more recent heliocentric ephemerides of the Solar System
are derived bounds for the value of a constant parameter $\alpha_0$ for the ELA
metric as well as the maximal corrections to perihelion advance and orbital
radii variation within this framework. Hence it is shown that employing the ELA
metric as a functional covariant parameterization to model gravitational
interactions corrections within the Solar System allows to maintain the
measurement projection standards constant over time, specifically both the
Astronomical Unit ($AU$) and the Gravitational constant ($G$). Also it is noted
that the effect obtained is not homogeneous for all planetary orbits
consistently with the diversity of estimates in the literature obtained
assuming Schwarzschild backgrounds.
| [
{
"created": "Thu, 8 Mar 2012 16:37:10 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Nov 2017 11:50:54 GMT",
"version": "v2"
}
] | 2017-11-07 | [
[
"Ferreira",
"P. Castelo",
""
]
] | In this work are computed analytical solutions for orbital motion on a background described by an Expanding Locally Anisotropic (ELA) metric ansatz. This metric interpolates between the Schwarzschild metric near the central mass and the Robertson-Walker metric describing the expanding cosmological background far from the central mass allowing for a fine-tuneable covariant parameterization of gravitational interactions corrections in between these two asymptotic limits. In particular it is shown that the decrease of the Sun's mass by radiation emission plus the General Relativity corrections due to the ELA metric background with respect to Schwarzschild backgrounds can be mapped to the reported yearly variation of the gravitational constant $\dot{G}$ through Kepler's third law. Based on the value of the heuristic fit corresponding to the more recent heliocentric ephemerides of the Solar System are derived bounds for the value of a constant parameter $\alpha_0$ for the ELA metric as well as the maximal corrections to perihelion advance and orbital radii variation within this framework. Hence it is shown that employing the ELA metric as a functional covariant parameterization to model gravitational interactions corrections within the Solar System allows to maintain the measurement projection standards constant over time, specifically both the Astronomical Unit ($AU$) and the Gravitational constant ($G$). Also it is noted that the effect obtained is not homogeneous for all planetary orbits consistently with the diversity of estimates in the literature obtained assuming Schwarzschild backgrounds. |
2005.00307 | Muhammed Amir | Muhammed Amir, Md Sabir Ali, Sunil D. Maharaj | Rotating five-dimensional electrically charged Bardeen regular black
holes | 24 pages, 8 figures, accepted for publication in CQG | Class. Quantum Grav. 37, 145014 (2020) | 10.1088/1361-6382/ab8eb7 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive a rotating counterpart of the five-dimensional electrically charged
Bardeen regular black holes spacetime by employing the Giampieri algorithm on
static one. The associated nonlinear electrodynamics source is computed in
order to justify the rotating solution. We thoroughly discuss the energy
conditions and the other properties of the rotating spacetime. The black hole
thermodynamics of the rotating spacetime is also presented. In particular, the
thermodynamic quantities such as the Hawking temperature and the heat capacity
are calculated and plotted to see the thermal behavior. The Hawking temperature
profile of the black hole implies that the regular black holes are thermally
colder than its singular counterpart. On the other hand, we find that the heat
capacity has two branches: the negative branch corresponds to the unstable
phase and the positive branch corresponds to that of the stable phase for a
suitable choice of the physical parameters characterizing the black holes.
| [
{
"created": "Fri, 1 May 2020 10:49:59 GMT",
"version": "v1"
}
] | 2020-08-19 | [
[
"Amir",
"Muhammed",
""
],
[
"Ali",
"Md Sabir",
""
],
[
"Maharaj",
"Sunil D.",
""
]
] | We derive a rotating counterpart of the five-dimensional electrically charged Bardeen regular black holes spacetime by employing the Giampieri algorithm on static one. The associated nonlinear electrodynamics source is computed in order to justify the rotating solution. We thoroughly discuss the energy conditions and the other properties of the rotating spacetime. The black hole thermodynamics of the rotating spacetime is also presented. In particular, the thermodynamic quantities such as the Hawking temperature and the heat capacity are calculated and plotted to see the thermal behavior. The Hawking temperature profile of the black hole implies that the regular black holes are thermally colder than its singular counterpart. On the other hand, we find that the heat capacity has two branches: the negative branch corresponds to the unstable phase and the positive branch corresponds to that of the stable phase for a suitable choice of the physical parameters characterizing the black holes. |
0906.2616 | Kazuya Fujio | Kazuya Fujio, Toshifumi Futamase | Appearance of classical Mixmaster Universe from the No-Boundary Quantum
State | 14 pages, 14 figures | Phys.Rev.D80:023504,2009 | 10.1103/PhysRevD.80.023504 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the appearance of the classical anisotropic universe from the
no-boundary quantum state according to the prescription proposed by Hartle,
Hawking and Hertog. Our model is homogeneous, anisotropic, closed universes
with a minimally coupled scalar field and cosmological constant. We found that
there are an ensemble of classical Lorentzian histories with anisotropies and
experience inflationary expansion at late time, and the probability of
histories with anisotropies are lower than isotropic histories. Thus the
no-boundary condition may be able to explain the emergence of our universe. If
the classical late time histories are extended back, some become singular by
the existence of initial anisotropies with large accelerations. However we do
not find any chaotic behavior of anisotropies near the initial singularity.
| [
{
"created": "Mon, 15 Jun 2009 06:25:45 GMT",
"version": "v1"
}
] | 2009-09-02 | [
[
"Fujio",
"Kazuya",
""
],
[
"Futamase",
"Toshifumi",
""
]
] | We investigate the appearance of the classical anisotropic universe from the no-boundary quantum state according to the prescription proposed by Hartle, Hawking and Hertog. Our model is homogeneous, anisotropic, closed universes with a minimally coupled scalar field and cosmological constant. We found that there are an ensemble of classical Lorentzian histories with anisotropies and experience inflationary expansion at late time, and the probability of histories with anisotropies are lower than isotropic histories. Thus the no-boundary condition may be able to explain the emergence of our universe. If the classical late time histories are extended back, some become singular by the existence of initial anisotropies with large accelerations. However we do not find any chaotic behavior of anisotropies near the initial singularity. |
0808.3240 | Kamal Nandi | Kamal K. Nandi, Ilnur Nigmatzyanov, Ramil Izmailov and Nail G.
Migranov | New Features of Extended Wormhole Solutions in the Scalar Field Gravity
Theories | 19 pages | Class.Quant.Grav.25:165020,2008 | 10.1088/0264-9381/25/16/165020 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The present paper reports interesting new features that wormhole solutions in
the scalar field gravity theory have. To demonstrate these, we obtain, by using
a slightly modified form of the Matos-Nunez algorithm, an extended class of
asymptotically flat wormhole solutions belonging to Einstein minimally coupled
scalar field theory. Generally, solutions in these theories do not represent
traversable wormholes due to the occurrence of curvature singularities.
However, the Ellis I solution of the Einstein minimally coupled theory, when
Wick rotated, yields Ellis class III solution, the latter representing a
singularity-free traversable wormhole. We see that Ellis I and III are not
essentially independent solutions. The Wick rotated seed solutions, extended by
the algorithm, contain two new parameters a and \delta;. The effect of the
parameter a on the geodesic motion of test particles reveals some remarkable
features. By arguing for Sagnac effect in the extended Wick rotated solution,
we find that the parameter a can indeed be interpreted as a rotation parameter
of the wormhole. The analyses reported here have wider applicability in that
they can very well be adopted in other theories, including in the string
theory.
| [
{
"created": "Sun, 24 Aug 2008 10:40:14 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Nandi",
"Kamal K.",
""
],
[
"Nigmatzyanov",
"Ilnur",
""
],
[
"Izmailov",
"Ramil",
""
],
[
"Migranov",
"Nail G.",
""
]
] | The present paper reports interesting new features that wormhole solutions in the scalar field gravity theory have. To demonstrate these, we obtain, by using a slightly modified form of the Matos-Nunez algorithm, an extended class of asymptotically flat wormhole solutions belonging to Einstein minimally coupled scalar field theory. Generally, solutions in these theories do not represent traversable wormholes due to the occurrence of curvature singularities. However, the Ellis I solution of the Einstein minimally coupled theory, when Wick rotated, yields Ellis class III solution, the latter representing a singularity-free traversable wormhole. We see that Ellis I and III are not essentially independent solutions. The Wick rotated seed solutions, extended by the algorithm, contain two new parameters a and \delta;. The effect of the parameter a on the geodesic motion of test particles reveals some remarkable features. By arguing for Sagnac effect in the extended Wick rotated solution, we find that the parameter a can indeed be interpreted as a rotation parameter of the wormhole. The analyses reported here have wider applicability in that they can very well be adopted in other theories, including in the string theory. |
1406.2611 | Lee Smolin | Lee Smolin | Positive energy in quantum gravity | 14 pages, no figures | Phys. Rev. D 90, 044034 (2014) | 10.1103/PhysRevD.90.044034 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper addresses the question of whether Witten's proof of positive ADM
energy for classical general relativity can be extended to give a proof of
positive energy for a non-perturbative quantization of general relativity. To
address this question, a set of conditions is shown to be sufficient for
showing the positivity of a Hamiltonian operator corresponding to the ADM
energy. One of these conditions is a particular factor ordering for the
constraints of general relativity, in a representation where the states are
functionals of the Ashtekar connection, and the auxiliary, Witten spinor.
These developments are partly based on results derived with Artem
Starodubtsev (unpublished notes, 2004).
| [
{
"created": "Tue, 10 Jun 2014 16:10:50 GMT",
"version": "v1"
}
] | 2014-08-20 | [
[
"Smolin",
"Lee",
""
]
] | This paper addresses the question of whether Witten's proof of positive ADM energy for classical general relativity can be extended to give a proof of positive energy for a non-perturbative quantization of general relativity. To address this question, a set of conditions is shown to be sufficient for showing the positivity of a Hamiltonian operator corresponding to the ADM energy. One of these conditions is a particular factor ordering for the constraints of general relativity, in a representation where the states are functionals of the Ashtekar connection, and the auxiliary, Witten spinor. These developments are partly based on results derived with Artem Starodubtsev (unpublished notes, 2004). |
2209.14394 | Flavio Bombacigno | S. Boudet, F. Bombacigno, F. Moretti and G. J. Olmo | Torsional birefringence in metric-affine Chern-Simons gravity:
gravitational waves in late-time cosmology | version accepted for publication in JCAP | JCAP01(2023)026 | 10.1088/1475-7516/2023/01/026 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | In the context of the metric-affine Chern-Simons gravity endowed with
projective invariance, we derive analytical solutions for torsion and
nonmetricity in the homogeneous and isotropic cosmological case, described by a
flat Friedmann-Robertson-Walker metric. We discuss in some details the general
properties of the cosmological solutions in the presence of a perfect fluid,
such as the dynamical stability and the emergence of big bounce points, and we
examine the structure of some specific solutions reproducing de Sitter and
power law behaviours for the scale factor. Then, we focus on first-order
perturbations in the de Sitter scenario, and we study the propagation of
gravitational waves in the adiabatic limit, looking at tensor and scalar
polarizations. In particular, we find that metric tensor modes couple to
torsion tensor components, leading to the appearance, as in the metric version
of Chern-Simons gravity, of birefringence, characterized by different
dispersion relations for the left and right circularized polarization states.
As a result, the purely tensor part of torsion propagates like a wave, while
nonmetricity decouples and behaves like a harmonic oscillator. Finally, we
discuss scalar modes, outlining as they decay exponentially in time and do not
propagate.
| [
{
"created": "Wed, 28 Sep 2022 19:35:58 GMT",
"version": "v1"
},
{
"created": "Tue, 4 Oct 2022 09:53:35 GMT",
"version": "v2"
},
{
"created": "Mon, 9 Jan 2023 20:30:17 GMT",
"version": "v3"
}
] | 2023-01-24 | [
[
"Boudet",
"S.",
""
],
[
"Bombacigno",
"F.",
""
],
[
"Moretti",
"F.",
""
],
[
"Olmo",
"G. J.",
""
]
] | In the context of the metric-affine Chern-Simons gravity endowed with projective invariance, we derive analytical solutions for torsion and nonmetricity in the homogeneous and isotropic cosmological case, described by a flat Friedmann-Robertson-Walker metric. We discuss in some details the general properties of the cosmological solutions in the presence of a perfect fluid, such as the dynamical stability and the emergence of big bounce points, and we examine the structure of some specific solutions reproducing de Sitter and power law behaviours for the scale factor. Then, we focus on first-order perturbations in the de Sitter scenario, and we study the propagation of gravitational waves in the adiabatic limit, looking at tensor and scalar polarizations. In particular, we find that metric tensor modes couple to torsion tensor components, leading to the appearance, as in the metric version of Chern-Simons gravity, of birefringence, characterized by different dispersion relations for the left and right circularized polarization states. As a result, the purely tensor part of torsion propagates like a wave, while nonmetricity decouples and behaves like a harmonic oscillator. Finally, we discuss scalar modes, outlining as they decay exponentially in time and do not propagate. |
gr-qc/0206018 | Oleg Zaslavskii | O. B. Zaslavskii | Thermodynamics of black holes with an infinite effective area of a
horizon | 24 pages. Accepted for publication in Class. Quant. Grav | Class.Quant.Grav. 19 (2002) 3783-3798 | 10.1088/0264-9381/19/14/317 | null | gr-qc hep-th | null | In some kinds of classical dilaton theory there exist black holes with (i)
infinite horizon area $A$ or infinite $F$ (the coefficient at curvature in
Lagrangian) and (ii) zero Hawking temperature $T_{H}$. For a generic static
black hole, without an assumption about spherical symmetry, we show that
infinite $A$ is compatible with a regularity of geometry in the case $T_{H}=0$
only. We also point out that infinite $T_{H}$ is incompatible with the
regularity of a horizon of a generic static black hole, both for finite or
infinite $A$. Direct application of the standard Euclidean approach in the case
of an infinite ''effective'' area of the horizon $A_{eff}=AF$ leads to
inconsistencies in the variational principle and gives for a black hole entropy
$S$ an indefinite expression, formally proportional to $T_{H}A_{eff}$. We show
that treating a horizon as an additional boundary (that is, adding to the
action some terms calculated on the horizon) may restore self-consistency of
the variational procedure, if $F$ near the horizon grows not too rapidly. We
apply this approach to Brans-Dicke black holes and obtain the same answer S=0
as for ''usual'' (for example, Reissner-Nordstr\"{o}m) extreme classical black
holes. We also consider the exact solution for a conformal coupling, when $A$
is finite but $F$ diverges and find that in the latter case both the standard
and modified approach give rise to an infinite action. Thus, this solution
represents a rare exception of a black hole without nontrivial thermal
properties.
| [
{
"created": "Thu, 6 Jun 2002 17:46:11 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Zaslavskii",
"O. B.",
""
]
] | In some kinds of classical dilaton theory there exist black holes with (i) infinite horizon area $A$ or infinite $F$ (the coefficient at curvature in Lagrangian) and (ii) zero Hawking temperature $T_{H}$. For a generic static black hole, without an assumption about spherical symmetry, we show that infinite $A$ is compatible with a regularity of geometry in the case $T_{H}=0$ only. We also point out that infinite $T_{H}$ is incompatible with the regularity of a horizon of a generic static black hole, both for finite or infinite $A$. Direct application of the standard Euclidean approach in the case of an infinite ''effective'' area of the horizon $A_{eff}=AF$ leads to inconsistencies in the variational principle and gives for a black hole entropy $S$ an indefinite expression, formally proportional to $T_{H}A_{eff}$. We show that treating a horizon as an additional boundary (that is, adding to the action some terms calculated on the horizon) may restore self-consistency of the variational procedure, if $F$ near the horizon grows not too rapidly. We apply this approach to Brans-Dicke black holes and obtain the same answer S=0 as for ''usual'' (for example, Reissner-Nordstr\"{o}m) extreme classical black holes. We also consider the exact solution for a conformal coupling, when $A$ is finite but $F$ diverges and find that in the latter case both the standard and modified approach give rise to an infinite action. Thus, this solution represents a rare exception of a black hole without nontrivial thermal properties. |
gr-qc/0406017 | Mu-Lin Yan | Mu-Lin Yan, Hua Bai | Quantum horizon and thermodynamics of black hole | 20 pages; LaTex file; No figure. To appear in "Progress in GR and QC
Research", Nova Science Pub. Inc | null | null | null | gr-qc hep-ph hep-th | null | A semi-classical reasoning leads to the non-commutativity of space and time
coordinates near the horizon of static non-extreme black hole, and renders the
classical horizon spreading to {\it Quantum Horizon} . In terms of the
background metric of the black hole with the {\it Quantum Horizon}, a quantum
field theory in curved space without ultraviolet divergency near the horizon is
formulated. In this formulism, the black hole thermodynamics is reproduced
correctly without both ambiguity and additional hypothesis in the deriving the
hole's Hawking radiations and entropies, and a new interesting prediction on
the number of radiative field modes $N$ is provided. Specifically, the main
results are follows: 1, Hawking radiations rightly emerge as an effect of
quantum tunneling through the quantum horizon, and hence the ambiguities due to
going across the singularity on the classical horizon were got rid of; 2, 't
Hooft's brick wall thickness hypothesis and the boundary condition imposed for
the field considered in his brick wall model were got rid of also, and related
physics has been interpreted; 3, The present theory is parameter free. So, the
theory has power to predict the multiplicity $N$ of radiative field modes
according to the requirement of normalization of Hawking-Bekenstein entropy. It
has been found that $N\simeq 162$, which is just in good agreement with one in
the Minimal Super-symmetric Standard Model. The studies in this paper represent
an attempt to reveal some physics near the horizon at Planck scale. This paper
serves a brief review on the author's works on this subject.
| [
{
"created": "Fri, 4 Jun 2004 15:08:34 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Yan",
"Mu-Lin",
""
],
[
"Bai",
"Hua",
""
]
] | A semi-classical reasoning leads to the non-commutativity of space and time coordinates near the horizon of static non-extreme black hole, and renders the classical horizon spreading to {\it Quantum Horizon} . In terms of the background metric of the black hole with the {\it Quantum Horizon}, a quantum field theory in curved space without ultraviolet divergency near the horizon is formulated. In this formulism, the black hole thermodynamics is reproduced correctly without both ambiguity and additional hypothesis in the deriving the hole's Hawking radiations and entropies, and a new interesting prediction on the number of radiative field modes $N$ is provided. Specifically, the main results are follows: 1, Hawking radiations rightly emerge as an effect of quantum tunneling through the quantum horizon, and hence the ambiguities due to going across the singularity on the classical horizon were got rid of; 2, 't Hooft's brick wall thickness hypothesis and the boundary condition imposed for the field considered in his brick wall model were got rid of also, and related physics has been interpreted; 3, The present theory is parameter free. So, the theory has power to predict the multiplicity $N$ of radiative field modes according to the requirement of normalization of Hawking-Bekenstein entropy. It has been found that $N\simeq 162$, which is just in good agreement with one in the Minimal Super-symmetric Standard Model. The studies in this paper represent an attempt to reveal some physics near the horizon at Planck scale. This paper serves a brief review on the author's works on this subject. |
2006.07122 | Wei-Liang Qian | Wei-Liang Qian, Kai Lin, Jian-Pin Wu, Bin Wang, and Rui-Hong Yue | On quasinormal frequencies of black hole perturbations with an external
source | 17 pages, 3 figures, accepted for publication on EPJC | null | 10.1140/epjc/s10052-020-08539-x | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the study of perturbations around black hole configurations, whether an
external source can influence the perturbation behavior is an interesting topic
to investigate. When the source acts as an initial pulse, it is intuitively
acceptable that the existing quasinormal frequencies will remain unchanged.
However, the confirmation of such an intuition is not trivial for the rotating
black hole, since the eigenvalues in the radial and angular parts of the master
equations are coupled. We show that for the rotating black holes, a moderate
source term in the master equation in the Laplace s-domain does not modify the
quasinormal modes. Furthermore, we generalize our discussions to the case where
the external source serves as a driving force. Different from an initial pulse,
an external source may further drive the system to experience new perturbation
modes. To be specific, novel dissipative singularities might be brought into
existence and enrich the pole structure. This is a physically relevant
scenario, due to its possible implication in modified gravity. Our arguments
are based on exploring the pole structure of the solution in the Laplace
s-domain with the presence of the external source. The analytical analyses are
verified numerically by solving the inhomogeneous differential equation and
extracting the dominant complex frequencies by employing the Prony method.
| [
{
"created": "Fri, 12 Jun 2020 12:30:11 GMT",
"version": "v1"
},
{
"created": "Tue, 4 Aug 2020 02:54:42 GMT",
"version": "v2"
},
{
"created": "Sun, 11 Oct 2020 12:49:56 GMT",
"version": "v3"
},
{
"created": "Thu, 15 Oct 2020 04:00:17 GMT",
"version": "v4"
},
{
"cr... | 2020-12-02 | [
[
"Qian",
"Wei-Liang",
""
],
[
"Lin",
"Kai",
""
],
[
"Wu",
"Jian-Pin",
""
],
[
"Wang",
"Bin",
""
],
[
"Yue",
"Rui-Hong",
""
]
] | In the study of perturbations around black hole configurations, whether an external source can influence the perturbation behavior is an interesting topic to investigate. When the source acts as an initial pulse, it is intuitively acceptable that the existing quasinormal frequencies will remain unchanged. However, the confirmation of such an intuition is not trivial for the rotating black hole, since the eigenvalues in the radial and angular parts of the master equations are coupled. We show that for the rotating black holes, a moderate source term in the master equation in the Laplace s-domain does not modify the quasinormal modes. Furthermore, we generalize our discussions to the case where the external source serves as a driving force. Different from an initial pulse, an external source may further drive the system to experience new perturbation modes. To be specific, novel dissipative singularities might be brought into existence and enrich the pole structure. This is a physically relevant scenario, due to its possible implication in modified gravity. Our arguments are based on exploring the pole structure of the solution in the Laplace s-domain with the presence of the external source. The analytical analyses are verified numerically by solving the inhomogeneous differential equation and extracting the dominant complex frequencies by employing the Prony method. |
2310.02338 | Bogdan Veklych | Bogdan Veklych | Is a Quantum Gravity Era Necessary? | (For the moderator: corrected two typos in section 4,
"direction"->"dimension" and "neutrino"->"antineutrino") | null | null | null | gr-qc | http://creativecommons.org/licenses/by-sa/4.0/ | We present the first published framework of the entirety of cosmological
history which is thoroughly classical (without any quantum-gravitational era or
singularities) and which passes all the known extensive consistency checks on
such a model, and discuss some of its possible cosmological implications, such
as its ability to account for the matter-antimatter asymmetry, dark flow, and
the Hubble tension, albeit at the cost of further assumptions.
| [
{
"created": "Tue, 3 Oct 2023 18:21:27 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Aug 2024 05:45:21 GMT",
"version": "v2"
}
] | 2024-08-15 | [
[
"Veklych",
"Bogdan",
""
]
] | We present the first published framework of the entirety of cosmological history which is thoroughly classical (without any quantum-gravitational era or singularities) and which passes all the known extensive consistency checks on such a model, and discuss some of its possible cosmological implications, such as its ability to account for the matter-antimatter asymmetry, dark flow, and the Hubble tension, albeit at the cost of further assumptions. |
2402.03266 | Igor Bogush Dr. | Igor Bogush, Kirill Kobialko, Dmitri Gal'tsov | Constructing massive particles surfaces in static spacetimes | 8 pages, revtex4-1 | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The procedure for constructing the massive particle surfaces in static
space-times is described in detail and the equivalence of the main results with
the results of the geodesic approach is demonstrated.
| [
{
"created": "Mon, 5 Feb 2024 18:22:42 GMT",
"version": "v1"
}
] | 2024-02-06 | [
[
"Bogush",
"Igor",
""
],
[
"Kobialko",
"Kirill",
""
],
[
"Gal'tsov",
"Dmitri",
""
]
] | The procedure for constructing the massive particle surfaces in static space-times is described in detail and the equivalence of the main results with the results of the geodesic approach is demonstrated. |
1912.00900 | Surajit Kalita | Surajit Kalita (IISc), Banibrata Mukhopadhyay (IISc) and T. R.
Govindarajan (IMSc) | Significantly super-Chandrasekhar mass-limit of white dwarfs in
noncommutative geometry | 19 pages including 1 figure; text is modified and references are
updated: Accepted for publication in IJMPD | IJMPD, 30, 5 (2021) 2150034 | 10.1142/S0218271821500346 | null | gr-qc astro-ph.HE astro-ph.SR hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Chandrasekhar made the startling discovery about nine decades back that the
mass of compact object white dwarf has a limiting value, once nuclear fusion
reactions stop therein. This is the Chandrasekhar mass-limit, which is
$\sim1.4M_\odot$ for a non-rotating non-magnetized white dwarf. On approaching
this limiting mass, a white dwarf is believed to spark off with an explosion
called type Ia supernova, which is considered to be a standard candle. However,
observations of several over-luminous, peculiar type Ia supernovae indicate
that the Chandrasekhar mass-limit to be significantly larger. By considering
noncommutativity among the components of position and momentum variables, hence
uncertainty in their measurements, at the quantum scales, we show that the mass
of white dwarfs could be significantly super-Chandrasekhar and thereby arrive
at a new mass-limit $\sim 2.6M_\odot$, explaining a possible origin of
over-luminous peculiar type Ia supernovae. The idea of noncommutativity, apart
from the Heisenberg's uncertainty principle, is there for quite sometime,
without any observational proof however. Our finding offers a plausible
astrophysical evidence of noncommutativity, arguing for a possible second
standard candle, which has many far-reaching implications.
| [
{
"created": "Tue, 26 Nov 2019 19:00:04 GMT",
"version": "v1"
},
{
"created": "Wed, 1 Jul 2020 14:07:49 GMT",
"version": "v2"
},
{
"created": "Wed, 13 Jan 2021 05:14:07 GMT",
"version": "v3"
}
] | 2021-04-27 | [
[
"Kalita",
"Surajit",
"",
"IISc"
],
[
"Mukhopadhyay",
"Banibrata",
"",
"IISc"
],
[
"Govindarajan",
"T. R.",
"",
"IMSc"
]
] | Chandrasekhar made the startling discovery about nine decades back that the mass of compact object white dwarf has a limiting value, once nuclear fusion reactions stop therein. This is the Chandrasekhar mass-limit, which is $\sim1.4M_\odot$ for a non-rotating non-magnetized white dwarf. On approaching this limiting mass, a white dwarf is believed to spark off with an explosion called type Ia supernova, which is considered to be a standard candle. However, observations of several over-luminous, peculiar type Ia supernovae indicate that the Chandrasekhar mass-limit to be significantly larger. By considering noncommutativity among the components of position and momentum variables, hence uncertainty in their measurements, at the quantum scales, we show that the mass of white dwarfs could be significantly super-Chandrasekhar and thereby arrive at a new mass-limit $\sim 2.6M_\odot$, explaining a possible origin of over-luminous peculiar type Ia supernovae. The idea of noncommutativity, apart from the Heisenberg's uncertainty principle, is there for quite sometime, without any observational proof however. Our finding offers a plausible astrophysical evidence of noncommutativity, arguing for a possible second standard candle, which has many far-reaching implications. |
gr-qc/9512044 | Francesco Belgiorno | F.Belgiorno and M.Martellini | Hawking Radiation Entropy and Horizon Divergences | 32 pages, uses Phyzzx | Phys.Rev. D53 (1996) 7073-7081 | 10.1103/PhysRevD.53.7073 | IFUM 521 (11/95) | gr-qc | null | We review the problem of divergences in one--loop thermodynamical quantities
for matter fields in thermal equilibrium on a black hole background. We discuss
a number of results obtained for various thermodynamical quantities. Then we
discuss the ansatz called ``literal interpretation" of zeroth law of black hole
mechanics and try to explain the diseases of the conical defect procedure in
light of this ansatz. Finally, an analysis of the consequences implied by our
ansatz on the calculation of the partition function is made.
| [
{
"created": "Thu, 28 Dec 1995 17:11:38 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Belgiorno",
"F.",
""
],
[
"Martellini",
"M.",
""
]
] | We review the problem of divergences in one--loop thermodynamical quantities for matter fields in thermal equilibrium on a black hole background. We discuss a number of results obtained for various thermodynamical quantities. Then we discuss the ansatz called ``literal interpretation" of zeroth law of black hole mechanics and try to explain the diseases of the conical defect procedure in light of this ansatz. Finally, an analysis of the consequences implied by our ansatz on the calculation of the partition function is made. |
gr-qc/0612169 | Alikram Aliev | Alikram N. Aliev | Higher Dimensional Rotating Charged Black Holes | To appear in the Proceedings of the Eleventh Marcel Grossmann
Meeting, Berlin, Germany, 23-29 Jule 2006, 3pp., World Scientific, Singapore
(2007) | null | null | null | gr-qc | null | We discuss a new analytic solution to the Einstein-Maxwell field equations
that describes electrically charged black holes with a slow rotation and with a
single angular momentum in all higher dimensions. We also compute the
gyromagnetic ratio of these black holes.
| [
{
"created": "Tue, 26 Dec 2006 21:11:36 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Aliev",
"Alikram N.",
""
]
] | We discuss a new analytic solution to the Einstein-Maxwell field equations that describes electrically charged black holes with a slow rotation and with a single angular momentum in all higher dimensions. We also compute the gyromagnetic ratio of these black holes. |
gr-qc/0012086 | Jean-Paul Mbelek | J.P. Mbelek and M. Lachieze-Rey | Theoretical Necessity of an External Scalar Field in the Kaluza-Klein
Theory (I) | 11 pages, LaTeX2e. Submitted to Classical and Quantum Gravity | null | null | null | gr-qc | null | We show that the principle of least action is generally inconsistent with the
usual Kaluza-Klein program, the higher dimensional Einstein-Hilbert action
being unbounded from below. This inconsistency is also present in other
theories with higher dimensions like supergravity. Hence, we conclude to the
necessity of an external scalar field to compensate this flaw.
| [
{
"created": "Thu, 21 Dec 2000 00:29:51 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Mbelek",
"J. P.",
""
],
[
"Lachieze-Rey",
"M.",
""
]
] | We show that the principle of least action is generally inconsistent with the usual Kaluza-Klein program, the higher dimensional Einstein-Hilbert action being unbounded from below. This inconsistency is also present in other theories with higher dimensions like supergravity. Hence, we conclude to the necessity of an external scalar field to compensate this flaw. |
1603.08405 | Philip D. Mannheim | Philip D. Mannheim | Conformal Invariance and the Metrication of the Fundamental Forces | revtex4, 7 pages. Essay written for the Gravity Research Foundation
2016 Awards for Essays on Gravitation | null | 10.1142/S021827181644003X | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We revisit Weyl's metrication (geometrization) of electromagnetism. We show
that by making Weyl's proposed geometric connection be pure imaginary, not only
are we able to metricate electromagnetism, an underlying local conformal
invariance makes the geometry be strictly Riemannian and prevents observational
gravity from being complex. Via torsion we achieve an analogous metrication for
axial-vector fields. We generalize our procedure to Yang-Mills theories, and
achieve a metrication of all the fundamental forces. Only in the gravity sector
does our approach differ from the standard picture of fundamental forces, with
our approach requiring that standard Einstein gravity be replaced by conformal
gravity. We show that quantum conformal gravity is a consistent and unitary
quantum gravitational theory, one that, unlike string theory, only requires
four spacetime dimensions.
| [
{
"created": "Mon, 28 Mar 2016 15:42:42 GMT",
"version": "v1"
}
] | 2016-11-15 | [
[
"Mannheim",
"Philip D.",
""
]
] | We revisit Weyl's metrication (geometrization) of electromagnetism. We show that by making Weyl's proposed geometric connection be pure imaginary, not only are we able to metricate electromagnetism, an underlying local conformal invariance makes the geometry be strictly Riemannian and prevents observational gravity from being complex. Via torsion we achieve an analogous metrication for axial-vector fields. We generalize our procedure to Yang-Mills theories, and achieve a metrication of all the fundamental forces. Only in the gravity sector does our approach differ from the standard picture of fundamental forces, with our approach requiring that standard Einstein gravity be replaced by conformal gravity. We show that quantum conformal gravity is a consistent and unitary quantum gravitational theory, one that, unlike string theory, only requires four spacetime dimensions. |
1207.3469 | Pankaj S. Joshi | Ravindra V. Saraykar and Pankaj S. Joshi | A Note on Genericity and Stability of Black Holes and Naked
Singularities in Dust Collapse | 6 pages, LaTex | null | null | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We comment here on the results in Ref [4] that showed naked singularities in
dynamical gravitational collapse of inhomogeneous dust to be stable but
non-generic. The definition of genericity used there is reconsidered. We point
out that genericity in terms of an open set, with a positive measure defined
suitably on the space of initial data, is physically more appropriate compared
to the dynamical systems theory definition used in [4] which makes both black
holes and naked singularities non-generic as collapse outcomes.
| [
{
"created": "Sat, 14 Jul 2012 23:57:25 GMT",
"version": "v1"
}
] | 2012-07-17 | [
[
"Saraykar",
"Ravindra V.",
""
],
[
"Joshi",
"Pankaj S.",
""
]
] | We comment here on the results in Ref [4] that showed naked singularities in dynamical gravitational collapse of inhomogeneous dust to be stable but non-generic. The definition of genericity used there is reconsidered. We point out that genericity in terms of an open set, with a positive measure defined suitably on the space of initial data, is physically more appropriate compared to the dynamical systems theory definition used in [4] which makes both black holes and naked singularities non-generic as collapse outcomes. |
1404.1566 | Shahar Hod | Shahar Hod | Self-gravitating ring of matter in orbit around a black hole: The
innermost stable circular orbit | 11 pages | The European Physical Journal C 74, 2840 (2014) | 10.1140/epjc/s10052-014-2840-4 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study analytically a black-hole-ring system which is composed of a
stationary axisymmetric ring of particles in orbit around a perturbed Kerr
black hole of mass $M$. In particular, we calculate the shift in the orbital
frequency of the innermost stable circular orbit (ISCO) due to the finite mass
$m$ of the orbiting ring. It is shown that for thin rings of half-thickness
$r\ll M$, the dominant finite-mass correction to the characteristic ISCO
frequency stems from the self-gravitational potential energy of the ring (a
term in the energy budget of the system which is quadratic in the mass $m$ of
the ring). This dominant correction to the ISCO frequency is of order
$O(\mu\ln(M/r))$, where $\mu\equiv m/M$ is the dimensionless mass of the ring.
We show that the ISCO frequency increases (as compared to the ISCO frequency of
an orbiting test-ring) due to the finite-mass effects of the self-gravitating
ring.
| [
{
"created": "Sun, 6 Apr 2014 11:25:44 GMT",
"version": "v1"
}
] | 2015-06-19 | [
[
"Hod",
"Shahar",
""
]
] | We study analytically a black-hole-ring system which is composed of a stationary axisymmetric ring of particles in orbit around a perturbed Kerr black hole of mass $M$. In particular, we calculate the shift in the orbital frequency of the innermost stable circular orbit (ISCO) due to the finite mass $m$ of the orbiting ring. It is shown that for thin rings of half-thickness $r\ll M$, the dominant finite-mass correction to the characteristic ISCO frequency stems from the self-gravitational potential energy of the ring (a term in the energy budget of the system which is quadratic in the mass $m$ of the ring). This dominant correction to the ISCO frequency is of order $O(\mu\ln(M/r))$, where $\mu\equiv m/M$ is the dimensionless mass of the ring. We show that the ISCO frequency increases (as compared to the ISCO frequency of an orbiting test-ring) due to the finite-mass effects of the self-gravitating ring. |
2103.05074 | Philip Beltracchi | Philip Beltracchi, Paolo Gondolo, and Emil Mottola | Surface Stress Tensor and Junction Conditions on a Rotating Null Horizon | Replaced with updated version, published at Phys. Rev. D 105, 024001
(2022) | null | 10.1103/PhysRevD.105.024001 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | The general form of the surface stress tensor of an infinitesimally thin
shell located on a rotating null horizon is derived, when different interior
and exterior geometries are joined there. Although the induced metric on the
surface must be the same approached from either side, the first derivatives of
the metric need not be. Such discontinuities lead to a Dirac
$\delta$-distribution in the Einstein tensor localized on the horizon. For a
general stationary axisymmetric geometry the surface stress tensor can be
expressed in terms of two geometric invariants that characterize the surface,
namely the discontinuities $[\kappa]$ and $[\cal J]$ of the surface gravity
$\kappa$ and angular momentum density $\cal J$. The Komar energy and angular
momentum are given in coordinates adapted to the Killing symmetries, and the
surface contributions to each determined in terms of $[\kappa]$ and $[\cal J]$.
Guided by these, a simple modification of the original Israel junction
conditions is verified directly from the Einstein tensor density to give the
correct finite result for the surface stress, when the normal $\boldsymbol n$
to the surface is allowed to tend continuously to a null vector. The relation
to Israel's original junction conditions, which fail on null surfaces, is
given. The modified junction conditions are suitable to the matching of a
rotating `black hole' exterior to any interior geometry joined at the Kerr null
horizon surface, even when the surface normal is itself discontinuous and the
Barrab\`es-Israel formalism is also inapplicable. This joining on a rotating
null horizon is purely of the matter shell type and does not contain a
propagating gravitational shock wave.
| [
{
"created": "Mon, 8 Mar 2021 21:05:39 GMT",
"version": "v1"
},
{
"created": "Mon, 3 Jan 2022 21:44:17 GMT",
"version": "v2"
}
] | 2022-01-12 | [
[
"Beltracchi",
"Philip",
""
],
[
"Gondolo",
"Paolo",
""
],
[
"Mottola",
"Emil",
""
]
] | The general form of the surface stress tensor of an infinitesimally thin shell located on a rotating null horizon is derived, when different interior and exterior geometries are joined there. Although the induced metric on the surface must be the same approached from either side, the first derivatives of the metric need not be. Such discontinuities lead to a Dirac $\delta$-distribution in the Einstein tensor localized on the horizon. For a general stationary axisymmetric geometry the surface stress tensor can be expressed in terms of two geometric invariants that characterize the surface, namely the discontinuities $[\kappa]$ and $[\cal J]$ of the surface gravity $\kappa$ and angular momentum density $\cal J$. The Komar energy and angular momentum are given in coordinates adapted to the Killing symmetries, and the surface contributions to each determined in terms of $[\kappa]$ and $[\cal J]$. Guided by these, a simple modification of the original Israel junction conditions is verified directly from the Einstein tensor density to give the correct finite result for the surface stress, when the normal $\boldsymbol n$ to the surface is allowed to tend continuously to a null vector. The relation to Israel's original junction conditions, which fail on null surfaces, is given. The modified junction conditions are suitable to the matching of a rotating `black hole' exterior to any interior geometry joined at the Kerr null horizon surface, even when the surface normal is itself discontinuous and the Barrab\`es-Israel formalism is also inapplicable. This joining on a rotating null horizon is purely of the matter shell type and does not contain a propagating gravitational shock wave. |
2308.16035 | Filip Ficek | Filip Ficek, Claude Warnick | Quasinormal modes of Reissner-Nordstr\"{o}m-AdS: the approach to
extremality | 15 pages, revised version | Class. Quantum Grav. 41 (2024) 085011 | 10.1088/1361-6382/ad35a0 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the quasinormal spectrum of scalar and axial perturbations of the
Reissner-Nordstr\"om-AdS black hole as the horizon approaches extremality. By
considering a foliation of the black hole by spacelike surfaces which intersect
the future horizon we implement numerical methods which are well behaved up to
and including the extremal limit and which admit initial data which is
nontrivial at the horizon. As extremality is approached we observe a transition
whereby the least damped mode ceases to be oscillatory in time, and the late
time signal changes qualitatively as a consequence.
| [
{
"created": "Wed, 30 Aug 2023 13:48:52 GMT",
"version": "v1"
},
{
"created": "Wed, 3 Apr 2024 10:34:27 GMT",
"version": "v2"
}
] | 2024-04-04 | [
[
"Ficek",
"Filip",
""
],
[
"Warnick",
"Claude",
""
]
] | We consider the quasinormal spectrum of scalar and axial perturbations of the Reissner-Nordstr\"om-AdS black hole as the horizon approaches extremality. By considering a foliation of the black hole by spacelike surfaces which intersect the future horizon we implement numerical methods which are well behaved up to and including the extremal limit and which admit initial data which is nontrivial at the horizon. As extremality is approached we observe a transition whereby the least damped mode ceases to be oscillatory in time, and the late time signal changes qualitatively as a consequence. |
gr-qc/9901070 | Nail | E.R. Bezerra de Mello, V.B. Bezerra and N.R. Khusnutdinov | Ground State Energy of Massive Scalar Field in the Global Monopole
Background | 8 pages, RevTex, no figures | null | null | null | gr-qc | null | We consider the ground state energy of scalar massive field in the spacetime
of a pointlike global monopole. Using zeta function regularization method we
obtain the heat kernel coefficients for this system. We show that the
coefficient $B_1$ contains additional contribution due to the non-trivial
topological structure of the spacetime. Taking into account the heat kernel
coefficients we obtain that the ground state energy of the scalar field is
zero. We also discuss our result using dimensional considerations.
| [
{
"created": "Mon, 25 Jan 1999 18:09:44 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"de Mello",
"E. R. Bezerra",
""
],
[
"Bezerra",
"V. B.",
""
],
[
"Khusnutdinov",
"N. R.",
""
]
] | We consider the ground state energy of scalar massive field in the spacetime of a pointlike global monopole. Using zeta function regularization method we obtain the heat kernel coefficients for this system. We show that the coefficient $B_1$ contains additional contribution due to the non-trivial topological structure of the spacetime. Taking into account the heat kernel coefficients we obtain that the ground state energy of the scalar field is zero. We also discuss our result using dimensional considerations. |
gr-qc/0103076 | Robert D. Klauber | Robert D. Klauber | New Perspectives on the Relativistically Rotating Disk and
Non-time-orthogonal Reference Frames | 30 pages including title page and 12 figures, plus references and
notes | Found.Phys.Lett. 11 (1998) 405-443 | null | null | gr-qc | null | The rotating disk problem is analyzed on the premise that proper
interpretation of experimental evidence leads to the conclusion that the
postulates upon which relativity theory is based, particularly the invariance
of the speed of light, are not applicable to rotating frames. Different
postulates based on the Sagnac experiment are proposed, and from these
postulates a new relativistic theory of rotating frames is developed following
steps similar to those initially followed by Einstein for rectilinear motion.
The resulting theory agrees with all experiments, resolves problems with the
traditional approach to the rotating disk, and exhibits both traditionally
relativistic and non-relativistic characteristics. Of particular note, no
Lorentz contraction exists on the rotating disk circumference, and the disk
surface, contrary to the assertions of Einstein and others, is found to be
Riemann flat. The variable speed of light found in the Sagnac experiment is
then shown to be characteristic of non-time-orthogonal reference frames, of
which the rotating frame is one. In addition, the widely accepted postulate for
the equivalence of inertial and non-inertial standard rods with zero relative
velocity, used liberally in prior rotating disk analyses, is shown to be
invalid for such frames. Further, the new theory stands alone in correctly
predicting what was heretofore considered a "spurious" non-null effect on the
order of 10^-13 found by Brillet and Hall in the most accurate Michelson-Morley
type test to date. The presentation is simple and pedagogic in order to make it
accessible to the non-specialist.
Key words: relativistic, rotating disk, Sagnac, rotating frame,
non-time-orthogonal frame.
| [
{
"created": "Thu, 22 Mar 2001 03:47:14 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Klauber",
"Robert D.",
""
]
] | The rotating disk problem is analyzed on the premise that proper interpretation of experimental evidence leads to the conclusion that the postulates upon which relativity theory is based, particularly the invariance of the speed of light, are not applicable to rotating frames. Different postulates based on the Sagnac experiment are proposed, and from these postulates a new relativistic theory of rotating frames is developed following steps similar to those initially followed by Einstein for rectilinear motion. The resulting theory agrees with all experiments, resolves problems with the traditional approach to the rotating disk, and exhibits both traditionally relativistic and non-relativistic characteristics. Of particular note, no Lorentz contraction exists on the rotating disk circumference, and the disk surface, contrary to the assertions of Einstein and others, is found to be Riemann flat. The variable speed of light found in the Sagnac experiment is then shown to be characteristic of non-time-orthogonal reference frames, of which the rotating frame is one. In addition, the widely accepted postulate for the equivalence of inertial and non-inertial standard rods with zero relative velocity, used liberally in prior rotating disk analyses, is shown to be invalid for such frames. Further, the new theory stands alone in correctly predicting what was heretofore considered a "spurious" non-null effect on the order of 10^-13 found by Brillet and Hall in the most accurate Michelson-Morley type test to date. The presentation is simple and pedagogic in order to make it accessible to the non-specialist. Key words: relativistic, rotating disk, Sagnac, rotating frame, non-time-orthogonal frame. |
2107.10237 | Dennis Obster | Dennis Obster, Naoki Sasakura | Counting tensor rank decompositions | 29 pages, 7 figures, 1 table | null | null | YITP-21-77 | gr-qc cs.NA hep-th math-ph math.MP math.NA | http://creativecommons.org/licenses/by/4.0/ | The tensor rank decomposition is a useful tool for the geometric
interpretation of the tensors in the canonical tensor model (CTM) of quantum
gravity. In order to understand the stability of this interpretation, it is
important to be able to estimate how many tensor rank decompositions can
approximate a given tensor. More precisely, finding an approximate symmetric
tensor rank decomposition of a symmetric tensor $Q$ with an error allowance
$\Delta$ is to find vectors $\phi^i$ satisfying $\|Q-\sum_{i=1}^R \phi^i\otimes
\phi^i\cdots \otimes \phi^i\|^2 \leq \Delta$. The volume of all possible such
$\phi^i$ is an interesting quantity which measures the amount of possible
decompositions for a tensor $Q$ within an allowance. While it would be
difficult to evaluate this quantity for each $Q$, we find an explicit formula
for a similar quantity by integrating over all $Q$ of unit norm. The expression
as a function of $\Delta$ is given by the product of a hypergeometric function
and a power function. We also extend the formula to generic decompositions of
non-symmetric tensors. The derivation depends on the existence (convergence) of
the partition function of a matrix model which appeared in the context of the
CTM.
| [
{
"created": "Tue, 20 Jul 2021 06:30:36 GMT",
"version": "v1"
}
] | 2021-07-22 | [
[
"Obster",
"Dennis",
""
],
[
"Sasakura",
"Naoki",
""
]
] | The tensor rank decomposition is a useful tool for the geometric interpretation of the tensors in the canonical tensor model (CTM) of quantum gravity. In order to understand the stability of this interpretation, it is important to be able to estimate how many tensor rank decompositions can approximate a given tensor. More precisely, finding an approximate symmetric tensor rank decomposition of a symmetric tensor $Q$ with an error allowance $\Delta$ is to find vectors $\phi^i$ satisfying $\|Q-\sum_{i=1}^R \phi^i\otimes \phi^i\cdots \otimes \phi^i\|^2 \leq \Delta$. The volume of all possible such $\phi^i$ is an interesting quantity which measures the amount of possible decompositions for a tensor $Q$ within an allowance. While it would be difficult to evaluate this quantity for each $Q$, we find an explicit formula for a similar quantity by integrating over all $Q$ of unit norm. The expression as a function of $\Delta$ is given by the product of a hypergeometric function and a power function. We also extend the formula to generic decompositions of non-symmetric tensors. The derivation depends on the existence (convergence) of the partition function of a matrix model which appeared in the context of the CTM. |
1912.09514 | Wolfgang Wieland | Jeevan Chandra Namburi and Wolfgang Wieland | Deformed Heisenberg charges in three-dimensional gravity | null | null | 10.1007/JHEP03(2020)175 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we consider the bulk plus boundary phase space for
three-dimensional gravity with negative cosmological constant for a particular
choice of conformal boundary conditions: the conformal class of the induced
metric at the boundary is kept fixed and the mean extrinsic curvature is
constrained to be one. Such specific conformal boundary conditions define
so-called Bryant surfaces, which can be classified completely in terms of
holomorphic maps from Riemann surfaces into the spinor bundle. To study the
observables and gauge symmetries of the resulting bulk plus boundary system, we
introduce an extended phase space, where these holomorphic maps are now part of
the gravitational bulk plus boundary phase space. The physical phase space is
obtained by introducing two sets of Kac-Moody currents, which are constrained
to vanish. The constraints are second-class and the corresponding Dirac bracket
yields an infinite-dimensional deformation of the Heisenberg algebra for the
spinor-valued surface charges. Finally, we compute the Poisson algebra among
the generators of conformal diffeomorphisms and demonstrate that there is no
central charge. Although the central charge vanishes and the boundary CFT is
likely non-unitary, we will argue that a version of the Cardy formula still
applies in this context, such that the entropy of the BTZ black hole can be
derived from the degeneracy of the eigenstates of quasi-local energy.
| [
{
"created": "Thu, 19 Dec 2019 19:33:15 GMT",
"version": "v1"
}
] | 2020-04-22 | [
[
"Namburi",
"Jeevan Chandra",
""
],
[
"Wieland",
"Wolfgang",
""
]
] | In this paper, we consider the bulk plus boundary phase space for three-dimensional gravity with negative cosmological constant for a particular choice of conformal boundary conditions: the conformal class of the induced metric at the boundary is kept fixed and the mean extrinsic curvature is constrained to be one. Such specific conformal boundary conditions define so-called Bryant surfaces, which can be classified completely in terms of holomorphic maps from Riemann surfaces into the spinor bundle. To study the observables and gauge symmetries of the resulting bulk plus boundary system, we introduce an extended phase space, where these holomorphic maps are now part of the gravitational bulk plus boundary phase space. The physical phase space is obtained by introducing two sets of Kac-Moody currents, which are constrained to vanish. The constraints are second-class and the corresponding Dirac bracket yields an infinite-dimensional deformation of the Heisenberg algebra for the spinor-valued surface charges. Finally, we compute the Poisson algebra among the generators of conformal diffeomorphisms and demonstrate that there is no central charge. Although the central charge vanishes and the boundary CFT is likely non-unitary, we will argue that a version of the Cardy formula still applies in this context, such that the entropy of the BTZ black hole can be derived from the degeneracy of the eigenstates of quasi-local energy. |
0910.3200 | Martin Bojowald | Martin Bojowald | A Momentous Arrow of Time | 23 pages, 3 figures, Chapter contributed to "The Arrow of Time" Ed.
L. Mersini-Houghton and R. Vaas (Springer-Verlag) | The Arrows of Time (Springer, Heidelberg 2012), pp.169-189 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Quantum cosmology offers a unique stage to address questions of time related
to its underlying (and perhaps truly quantum dynamical) meaning as well as its
origin. Some of these issues can be analyzed with a general scheme of quantum
cosmology, others are best seen in loop quantum cosmology. The latter's status
is still incomplete, and so no full scenario has yet emerged. Nevertheless,
using properties that have a potential of pervading more complicated and
realistic models, a vague picture shall be sketched here. It suggests the
possibility of deriving a beginning within a beginningless theory, by applying
cosmic forgetfulness to an early history of the universe.
| [
{
"created": "Fri, 16 Oct 2009 19:46:57 GMT",
"version": "v1"
}
] | 2012-07-25 | [
[
"Bojowald",
"Martin",
""
]
] | Quantum cosmology offers a unique stage to address questions of time related to its underlying (and perhaps truly quantum dynamical) meaning as well as its origin. Some of these issues can be analyzed with a general scheme of quantum cosmology, others are best seen in loop quantum cosmology. The latter's status is still incomplete, and so no full scenario has yet emerged. Nevertheless, using properties that have a potential of pervading more complicated and realistic models, a vague picture shall be sketched here. It suggests the possibility of deriving a beginning within a beginningless theory, by applying cosmic forgetfulness to an early history of the universe. |
1608.06187 | Kent Yagi | Kent Yagi and Nicolas Yunes | Approximate Universal Relations among Tidal Parameters for Neutron Star
Binaries | 42 pages, 18 figures; matches the published version, a few typos
corrected | null | 10.1088/1361-6382/34/1/015006 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | One of largest uncertainties in nuclear physics is the relation between the
pressure and density of supranuclear matter: the equation of state. Some of
this uncertainty may be removed through future gravitational wave observations
of neutron star binaries by extracting the tidal deformabilities (or Love
numbers) of neutron stars. Previous studies showed that only a certain
combination of the individual deformabilities of each body (chirp tidal
deformability) can be measured with second-generation gravitational wave
interferometers, such as Adv. LIGO, due to correlations between the individual
deformabilities. To overcome this, we search for approximately universal (or
equation-of-state independent) relations between two combinations of the
individual tidal deformabilities, such that once one of them has been measured,
the other can be automatically obtained and the individual ones decoupled
through these relations. We find an approximately universal relation between
the symmetric and the anti-symmetric combination of the individual tidal
deformabilities that is equation-of-state-insensitive to $20\%$ for binaries
with masses less than $1.7M_\odot$. We show that these relations can be used to
eliminate a combination of the tidal parameters from the list of model
parameters, thus breaking degeneracies and improving the accuracy in parameter
estimation. A simple study shows that the universal relations can improve the
accuracy in the extraction of the symmetric combination of tidal parameters by
as much as an order of magnitude, making the overall accuracy in the extraction
of this parameter slightly better than that of the chirp tidal deformability.
These new universal relations and the improved measurement accuracy on tidal
parameters not only are important to astrophysics and nuclear physics, but also
impact our ability to probe extreme gravity with gravitational waves and
cosmology.
| [
{
"created": "Mon, 22 Aug 2016 14:53:38 GMT",
"version": "v1"
},
{
"created": "Sun, 14 Oct 2018 02:15:03 GMT",
"version": "v2"
}
] | 2018-10-16 | [
[
"Yagi",
"Kent",
""
],
[
"Yunes",
"Nicolas",
""
]
] | One of largest uncertainties in nuclear physics is the relation between the pressure and density of supranuclear matter: the equation of state. Some of this uncertainty may be removed through future gravitational wave observations of neutron star binaries by extracting the tidal deformabilities (or Love numbers) of neutron stars. Previous studies showed that only a certain combination of the individual deformabilities of each body (chirp tidal deformability) can be measured with second-generation gravitational wave interferometers, such as Adv. LIGO, due to correlations between the individual deformabilities. To overcome this, we search for approximately universal (or equation-of-state independent) relations between two combinations of the individual tidal deformabilities, such that once one of them has been measured, the other can be automatically obtained and the individual ones decoupled through these relations. We find an approximately universal relation between the symmetric and the anti-symmetric combination of the individual tidal deformabilities that is equation-of-state-insensitive to $20\%$ for binaries with masses less than $1.7M_\odot$. We show that these relations can be used to eliminate a combination of the tidal parameters from the list of model parameters, thus breaking degeneracies and improving the accuracy in parameter estimation. A simple study shows that the universal relations can improve the accuracy in the extraction of the symmetric combination of tidal parameters by as much as an order of magnitude, making the overall accuracy in the extraction of this parameter slightly better than that of the chirp tidal deformability. These new universal relations and the improved measurement accuracy on tidal parameters not only are important to astrophysics and nuclear physics, but also impact our ability to probe extreme gravity with gravitational waves and cosmology. |
1304.6191 | Kazuharu Bamba | Kazuharu Bamba, Shin'ichi Nojiri and Sergei D. Odintsov | Effective $F(T)$ gravity from the higher-dimensional Kaluza-Klein and
Randall-Sundrum theories | 5 pages, no figure, version accepted for publication in Physics
Letters B | Physics Letters B 725 (2013) 368-371 | 10.1016/j.physletb.2013.07.052 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We explore the four-dimensional effective $F(T)$ gravity with $T$ the torsion
scalar in teleparallelism originating from higher-dimensional space-time
theories, in particular the Kaluza-Klein (KK) and Randall-Sundrum (RS)
theories. First, through the KK dimensional reduction from the five-dimensional
space-time, we obtain the four-dimensional effective theory of $F(T)$ gravity
with its coupling to a scalar field. Second, taking the RS type-II model in
which there exist the five-dimensional Anti-de Sitter (AdS) space-time with
four-dimensional Friedmann-Lema\^{i}tre-Robertson-Walker (FLRW) brane, we find
that there will appear the contribution of $F(T)$ gravity on the
four-dimensional FLRW brane. It is demonstrated that inflation and the dark
energy dominated stage can be realized in the KK and RS models, respectively,
due to the effect of only the torsion in teleparallelism without that of the
curvature.
| [
{
"created": "Tue, 23 Apr 2013 07:44:36 GMT",
"version": "v1"
},
{
"created": "Mon, 29 Apr 2013 10:24:33 GMT",
"version": "v2"
},
{
"created": "Wed, 24 Jul 2013 07:41:50 GMT",
"version": "v3"
}
] | 2013-09-03 | [
[
"Bamba",
"Kazuharu",
""
],
[
"Nojiri",
"Shin'ichi",
""
],
[
"Odintsov",
"Sergei D.",
""
]
] | We explore the four-dimensional effective $F(T)$ gravity with $T$ the torsion scalar in teleparallelism originating from higher-dimensional space-time theories, in particular the Kaluza-Klein (KK) and Randall-Sundrum (RS) theories. First, through the KK dimensional reduction from the five-dimensional space-time, we obtain the four-dimensional effective theory of $F(T)$ gravity with its coupling to a scalar field. Second, taking the RS type-II model in which there exist the five-dimensional Anti-de Sitter (AdS) space-time with four-dimensional Friedmann-Lema\^{i}tre-Robertson-Walker (FLRW) brane, we find that there will appear the contribution of $F(T)$ gravity on the four-dimensional FLRW brane. It is demonstrated that inflation and the dark energy dominated stage can be realized in the KK and RS models, respectively, due to the effect of only the torsion in teleparallelism without that of the curvature. |
1512.07473 | Parampreet Singh | Parampreet Singh, S. K. Soni | On the relationship between the modifications to the Raychaudhuri
equation and the canonical Hamiltonian structures | 22 pages with two new plots. Discussion on uniqueness added, and
possible links with existing models expanded. Periodicity for 'generalized
polymerized' theory and its comparison with standard polymerization
discussed. References added. To appear in CQG | Class. Quant. Grav 33 (2016) 125001 | 10.1088/0264-9381/33/12/125001 | null | gr-qc astro-ph.CO hep-th physics.class-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The problem of obtaining canonical Hamiltonian structures from the equations
of motion, without any knowledge of the action, is studied in the context of
the spatially flat Friedmann-Robertson-Walker models. Modifications to
Raychaudhuri equation are implemented independently as quadratic and cubic
terms of energy density without introducing additional degrees of freedom.
Depending on their sign, modifications make gravity repulsive above a curvature
scale for matter satisfying strong energy condition, or more attractive than in
the classical theory. Canonical structure of the modified theories is
determined demanding that the total Hamiltonian be a linear combination of
gravity and matter Hamiltonians. In the quadratic repulsive case, the modified
canonical phase space of gravity is a polymerized phase space with canonical
momentum as inverse trigonometric function of Hubble rate; the canonical
Hamiltonian can be identified with the effective Hamiltonian in loop quantum
cosmology. The repulsive cubic modification results in a `generalized
polymerized' canonical phase space. Both of the repulsive modifications are
found to yield singularity avoidance. In contrast, the quadratic and cubic
attractive modifications result in a canonical phase space in which canonical
momentum is non-trigonometric and singularities persist. Our results hint on
connections between repulsive/attractive nature of modifications to gravity
arising from gravitational sector and polymerized/non-polymerized gravitational
phase space.
| [
{
"created": "Wed, 23 Dec 2015 14:01:46 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Apr 2016 15:04:59 GMT",
"version": "v2"
}
] | 2016-05-18 | [
[
"Singh",
"Parampreet",
""
],
[
"Soni",
"S. K.",
""
]
] | The problem of obtaining canonical Hamiltonian structures from the equations of motion, without any knowledge of the action, is studied in the context of the spatially flat Friedmann-Robertson-Walker models. Modifications to Raychaudhuri equation are implemented independently as quadratic and cubic terms of energy density without introducing additional degrees of freedom. Depending on their sign, modifications make gravity repulsive above a curvature scale for matter satisfying strong energy condition, or more attractive than in the classical theory. Canonical structure of the modified theories is determined demanding that the total Hamiltonian be a linear combination of gravity and matter Hamiltonians. In the quadratic repulsive case, the modified canonical phase space of gravity is a polymerized phase space with canonical momentum as inverse trigonometric function of Hubble rate; the canonical Hamiltonian can be identified with the effective Hamiltonian in loop quantum cosmology. The repulsive cubic modification results in a `generalized polymerized' canonical phase space. Both of the repulsive modifications are found to yield singularity avoidance. In contrast, the quadratic and cubic attractive modifications result in a canonical phase space in which canonical momentum is non-trigonometric and singularities persist. Our results hint on connections between repulsive/attractive nature of modifications to gravity arising from gravitational sector and polymerized/non-polymerized gravitational phase space. |
0810.4376 | Matt Visser | Jozef Skakala (Victoria University of Wellington) and Matt Visser
(Victoria University of Wellington) | Birefringence in pseudo-Finsler spacetimes | 8 pages; uses jpconf.cls Talk delivered by Jozef Skakala at the NEB
XIII conference, (Recent Developments in Gravity), Thessalonika, Greece, June
2008 | J.Phys.Conf.Ser.189:012037,2009 | 10.1088/1742-6596/189/1/012037 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Based on the analogue spacetime programme, and many other ideas currently
mooted in "quantum gravity", there is considerable ongoing speculation that the
usual pseudo-Riemannian (Lorentzian) manifolds of general relativity might
eventually be modified at short distances. Two specific modifications that are
often advocated are the adoption of Finsler geometries (or more specifically,
pseudo-Finsler spacetimes) and the possibility of birefringence (or more
generally, multi-refringence). We have investigated the possibility of whether
it is possible to usefully and cleanly deal with these two possibilities
simultaneously. That is, given two (or more) "signal cones": Is it possible to
naturally and intuitively construct a "unified" pseudo-Finsler spacetime such
that the pseudo-Finsler metric is null on these "signal cones", but has no
other zeros or singularities? Our results are much less encouraging than we had
originally hoped, and suggest that while pseudo-Finsler spacetimes are
certainly useful constructs, it is physically more appropriate to think of
physics as taking place in a single topological manifold that carries several
distinct pseudo-Finsler metrics, one for each polarization mode.
| [
{
"created": "Fri, 24 Oct 2008 04:12:40 GMT",
"version": "v1"
}
] | 2009-11-05 | [
[
"Skakala",
"Jozef",
"",
"Victoria University of Wellington"
],
[
"Visser",
"Matt",
"",
"Victoria University of Wellington"
]
] | Based on the analogue spacetime programme, and many other ideas currently mooted in "quantum gravity", there is considerable ongoing speculation that the usual pseudo-Riemannian (Lorentzian) manifolds of general relativity might eventually be modified at short distances. Two specific modifications that are often advocated are the adoption of Finsler geometries (or more specifically, pseudo-Finsler spacetimes) and the possibility of birefringence (or more generally, multi-refringence). We have investigated the possibility of whether it is possible to usefully and cleanly deal with these two possibilities simultaneously. That is, given two (or more) "signal cones": Is it possible to naturally and intuitively construct a "unified" pseudo-Finsler spacetime such that the pseudo-Finsler metric is null on these "signal cones", but has no other zeros or singularities? Our results are much less encouraging than we had originally hoped, and suggest that while pseudo-Finsler spacetimes are certainly useful constructs, it is physically more appropriate to think of physics as taking place in a single topological manifold that carries several distinct pseudo-Finsler metrics, one for each polarization mode. |
2308.03068 | Yan-Gang Miao | Hao Yang, Chang-Jiang Yu, Yan-Gang Miao | Preliminary analyses on dynamics and thermodynamics of rotating regular
black holes | v1: 33 pages, 2 figures; v2: 37 pages, modifications and one
reference added, final version to appear in Chinese Physics C | Chinese Physics C 48 (2024) 075101 | 10.1088/1674-1137/ad34c1 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the dynamic and thermodynamic laws governing rotating regular
black holes. By analyzing dynamic properties, i.e., the interaction between
scalar particles and rotating regular black holes, we establish the criteria
that determine whether such black holes satisfy the laws of thermodynamics or
not. In addition, we provide the general form of conserved quantities related
to rotating regular black holes, including the relevant flows associated with
neutral scalar particles. Meanwhile, we reexamine the relationship between the
third law of thermodynamics and weak cosmic censorship conjecture for rotating
regular black holes. In accordance with the criteria mentioned above, we
discuss the laws of thermodynamics for three models of rotating regular black
holes: Rotating Hayward black holes, Kerr black-bounce solutions, and loop
quantum gravity black holes. Our findings indicate that none of the three
models satisfies the first law of thermodynamics. In particular, the first and
third models fail to comply with the three laws of thermodynamics, while the
second model satisfies only the second and third laws of thermodynamics.
Finally, we attempt to rescue the laws of thermodynamics by modifying entropy
or extending phase space. However, the two scenarios are not able to ensure the
three laws of thermodynamics in the three models, which reveals an unusual
property of rotating regular black holes.
| [
{
"created": "Sun, 6 Aug 2023 09:39:56 GMT",
"version": "v1"
},
{
"created": "Sat, 18 May 2024 01:40:28 GMT",
"version": "v2"
}
] | 2024-05-21 | [
[
"Yang",
"Hao",
""
],
[
"Yu",
"Chang-Jiang",
""
],
[
"Miao",
"Yan-Gang",
""
]
] | We investigate the dynamic and thermodynamic laws governing rotating regular black holes. By analyzing dynamic properties, i.e., the interaction between scalar particles and rotating regular black holes, we establish the criteria that determine whether such black holes satisfy the laws of thermodynamics or not. In addition, we provide the general form of conserved quantities related to rotating regular black holes, including the relevant flows associated with neutral scalar particles. Meanwhile, we reexamine the relationship between the third law of thermodynamics and weak cosmic censorship conjecture for rotating regular black holes. In accordance with the criteria mentioned above, we discuss the laws of thermodynamics for three models of rotating regular black holes: Rotating Hayward black holes, Kerr black-bounce solutions, and loop quantum gravity black holes. Our findings indicate that none of the three models satisfies the first law of thermodynamics. In particular, the first and third models fail to comply with the three laws of thermodynamics, while the second model satisfies only the second and third laws of thermodynamics. Finally, we attempt to rescue the laws of thermodynamics by modifying entropy or extending phase space. However, the two scenarios are not able to ensure the three laws of thermodynamics in the three models, which reveals an unusual property of rotating regular black holes. |
2404.19056 | Tayyaba Naz | Tayyaba Naz, Adnan Malik, Zenab Ramay | Anisotropic Quark Stars in Modified $f(R,T)$ Gravity utilizing Tolman V
potential | 16 pages, 17 figures, submitted for publication | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Alternative gravity theory is currently an incredibly significant technique
for addressing some enduring experimental difficulties, such as the universe's
dark region. They may also be employed in celestial cosmology, producing
results that are a stage beyond those found using Einstein's General
Relativity. In this study, we examine the characteristics of anisotropic
spherically symmetric stellar structures in the context of modified $f(R,T)$
gravity. In order to explain the distinctive characteristics of compact
objects, we investigate how the fluid distribution in the star model is
affected by the MIT bag model equation of state. By using Tolman V metric
potentials, we establish the field equations, and by employing the experimental
data of the three observed stars, we identify the values of unknown parameters.
By using a realistic $f(R,T)$ model, we investigate the effect of the energy
density, anisotropic factor, transversal and radial pressure within the cores
of the aforementioned stars for a particular amount of the Bag constant.
Further, we examine the stability of the cosmic structure and the physical
validity of our suggested model via equilibrium conditions, energy, and
causality parameters. To conclude, the physical conditions are fulfilled by our
model, and the magnitude of the Bag constant agrees with the experimental data,
demonstrating the model's feasibility.
| [
{
"created": "Mon, 29 Apr 2024 18:51:56 GMT",
"version": "v1"
}
] | 2024-05-01 | [
[
"Naz",
"Tayyaba",
""
],
[
"Malik",
"Adnan",
""
],
[
"Ramay",
"Zenab",
""
]
] | Alternative gravity theory is currently an incredibly significant technique for addressing some enduring experimental difficulties, such as the universe's dark region. They may also be employed in celestial cosmology, producing results that are a stage beyond those found using Einstein's General Relativity. In this study, we examine the characteristics of anisotropic spherically symmetric stellar structures in the context of modified $f(R,T)$ gravity. In order to explain the distinctive characteristics of compact objects, we investigate how the fluid distribution in the star model is affected by the MIT bag model equation of state. By using Tolman V metric potentials, we establish the field equations, and by employing the experimental data of the three observed stars, we identify the values of unknown parameters. By using a realistic $f(R,T)$ model, we investigate the effect of the energy density, anisotropic factor, transversal and radial pressure within the cores of the aforementioned stars for a particular amount of the Bag constant. Further, we examine the stability of the cosmic structure and the physical validity of our suggested model via equilibrium conditions, energy, and causality parameters. To conclude, the physical conditions are fulfilled by our model, and the magnitude of the Bag constant agrees with the experimental data, demonstrating the model's feasibility. |
2007.01145 | Kirill Bronnikov | K.A. Bronnikov, V.G. Krechet, V.B. Oshurko | Rotating Melvin-like universes and wormholes in general relativity | 11 pages, no figures | Symmetry 2020, 12 1306 (2020) | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We find a family of exact solutions to the Einstein-Maxwell equations for
rotating cylindrically symmetric distributions of a perfect fluid with the
equation of state $p = w\rho$ ($|w| < 1$), carrying a circular electric current
in the angular direction. This current creates a magnetic field along the $z$
axis. Some of the solutions describe geometries resembling that of Melvin's
static magnetic universe and contain a regular symmetry axis, while some others
(in the case $w > 0$) describe traversable wormhole geometries which do not
contain a symmetry axis. Unlike Melvin's solution, those with rotation and a
magnetic field cannot be vacuum and require a current. The wormhole solutions
admit matching with flat-space regions on both sides of the throat, thus
forming a cylindrical wormhole configuration potentially visible for distant
observers residing in flat or weakly curved parts of space. The thin shells,
located at junctions between the inner (wormhole) and outer (flat) regions,
consist of matter satisfying the Weak Energy Condition under a proper choice of
the free parameters of the model, and thus we obtain new examples of
phantom-free wormhole models in general relativity. In the limit $w \to 1$, the
magnetic field tends to zero, and the wormhole model tends to the one obtained
previously, where the source of gravity is stiff matter with the equation of
state $p = \rho$.
| [
{
"created": "Thu, 2 Jul 2020 14:30:17 GMT",
"version": "v1"
}
] | 2020-10-20 | [
[
"Bronnikov",
"K. A.",
""
],
[
"Krechet",
"V. G.",
""
],
[
"Oshurko",
"V. B.",
""
]
] | We find a family of exact solutions to the Einstein-Maxwell equations for rotating cylindrically symmetric distributions of a perfect fluid with the equation of state $p = w\rho$ ($|w| < 1$), carrying a circular electric current in the angular direction. This current creates a magnetic field along the $z$ axis. Some of the solutions describe geometries resembling that of Melvin's static magnetic universe and contain a regular symmetry axis, while some others (in the case $w > 0$) describe traversable wormhole geometries which do not contain a symmetry axis. Unlike Melvin's solution, those with rotation and a magnetic field cannot be vacuum and require a current. The wormhole solutions admit matching with flat-space regions on both sides of the throat, thus forming a cylindrical wormhole configuration potentially visible for distant observers residing in flat or weakly curved parts of space. The thin shells, located at junctions between the inner (wormhole) and outer (flat) regions, consist of matter satisfying the Weak Energy Condition under a proper choice of the free parameters of the model, and thus we obtain new examples of phantom-free wormhole models in general relativity. In the limit $w \to 1$, the magnetic field tends to zero, and the wormhole model tends to the one obtained previously, where the source of gravity is stiff matter with the equation of state $p = \rho$. |
gr-qc/0110110 | Gaetano Lambiase | G. Lambiase | Probing the Brans-Dicke Gravitational Field by Cerenkov Radiation | 8 pages, no figures | Europhys.Lett. 56 (2001) 778-783 | 10.1209/epl/i2001-00366-3 | null | gr-qc | null | The possibility that a charged particle propagating in a gravitational field
described by Brans-Dicke theory of gravity could emit Cerenkov radiation is
explored. This process is kinematically allowed depending on parameters
occurring in the theory. The Cerenkov effect disappears as the BD parameter
omega tends to inftinity, i.e. in the limit in which the Einstein theory is
recovered, giving a signature to probe the validity of the Brans-Dicke theory.
| [
{
"created": "Thu, 25 Oct 2001 17:55:51 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Lambiase",
"G.",
""
]
] | The possibility that a charged particle propagating in a gravitational field described by Brans-Dicke theory of gravity could emit Cerenkov radiation is explored. This process is kinematically allowed depending on parameters occurring in the theory. The Cerenkov effect disappears as the BD parameter omega tends to inftinity, i.e. in the limit in which the Einstein theory is recovered, giving a signature to probe the validity of the Brans-Dicke theory. |
gr-qc/0602063 | Samad Khakshournia | Shahram Khosravi, Samad Khakshournia, Reza Mansouri | Evolution of Thick Walls in Curved Spacetimes | 8 pages, 1 figure | Class.Quant.Grav. 23 (2006) 5927-5940 | 10.1088/0264-9381/23/20/014 | null | gr-qc | null | We generalize our previous thick shell formalism to incorporate any
codimension-1 thick wall with a peculiar velocity and proper thickness bounded
by arbitrary spacetimes. Within this new formulation we obtain the equation of
motion of a spherically symmetric dust thick shell immersed in vacuum as well
as in Friedmann-Robertson-Walker spacetimes.
| [
{
"created": "Thu, 16 Feb 2006 11:47:40 GMT",
"version": "v1"
},
{
"created": "Sat, 30 Sep 2006 12:50:23 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Khosravi",
"Shahram",
""
],
[
"Khakshournia",
"Samad",
""
],
[
"Mansouri",
"Reza",
""
]
] | We generalize our previous thick shell formalism to incorporate any codimension-1 thick wall with a peculiar velocity and proper thickness bounded by arbitrary spacetimes. Within this new formulation we obtain the equation of motion of a spherically symmetric dust thick shell immersed in vacuum as well as in Friedmann-Robertson-Walker spacetimes. |
0709.3703 | Johann Kronthaler | Johann Kronthaler | Decay Rates for Spherical Scalar Waves in the Schwarzschild Geometry | 34 pages | null | null | null | gr-qc | null | The Cauchy problem is considered for the scalar wave equation in the
Schwarzschild geometry. Using an integral spectral representation we derive the
exact decay rate for solutions of the Cauchy problem with spherical symmetric
initial data, which is smooth and compactly supported outside the event
horizon.
| [
{
"created": "Mon, 24 Sep 2007 08:07:17 GMT",
"version": "v1"
}
] | 2007-09-25 | [
[
"Kronthaler",
"Johann",
""
]
] | The Cauchy problem is considered for the scalar wave equation in the Schwarzschild geometry. Using an integral spectral representation we derive the exact decay rate for solutions of the Cauchy problem with spherical symmetric initial data, which is smooth and compactly supported outside the event horizon. |
2106.00674 | Jorge Pullin | Florencia Ben\'itez, Rodolfo Gambini, Steven L. Liebling, Jorge Pullin | Criticality in the collapse of spherically symmetric massless scalar
fields in semi-classical loop quantum gravity | 7 pages, RevTex | Phys. Rev. D 104, 024008 (2021) | 10.1103/PhysRevD.104.024008 | LSU-REL-060121 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In a recent paper we showed that the collapse to a black hole in
one-parameter families of initial data for massless, minimally coupled scalar
fields in spherically symmetric semi-classical loop quantum gravity exhibited a
universal mass scaling similar to the one in classical general relativity. In
particular, no evidence of a mass gap appeared as had been suggested by
previous studies. The lack of a mass gap indicated the possible existence of a
self-similar critical solution as in general relativity. Here we provide
further evidence for its existence. Using an adaptive mesh refinement code, we
show that "echoes" arise as a result of the discrete self-similarity in
space-time. We also show the existence of "wiggles" in the mass scaling
relation, as in the classical theory. The results from the semi-classical
theory agree well with those of classical general relativity unless one takes
unrealistically large values for the polymerization parameter.
| [
{
"created": "Tue, 1 Jun 2021 17:58:41 GMT",
"version": "v1"
}
] | 2021-07-07 | [
[
"Benítez",
"Florencia",
""
],
[
"Gambini",
"Rodolfo",
""
],
[
"Liebling",
"Steven L.",
""
],
[
"Pullin",
"Jorge",
""
]
] | In a recent paper we showed that the collapse to a black hole in one-parameter families of initial data for massless, minimally coupled scalar fields in spherically symmetric semi-classical loop quantum gravity exhibited a universal mass scaling similar to the one in classical general relativity. In particular, no evidence of a mass gap appeared as had been suggested by previous studies. The lack of a mass gap indicated the possible existence of a self-similar critical solution as in general relativity. Here we provide further evidence for its existence. Using an adaptive mesh refinement code, we show that "echoes" arise as a result of the discrete self-similarity in space-time. We also show the existence of "wiggles" in the mass scaling relation, as in the classical theory. The results from the semi-classical theory agree well with those of classical general relativity unless one takes unrealistically large values for the polymerization parameter. |
2010.15628 | Alessandro Tronconi | A. Y. Kamenshchik, A. Tronconi, G. Venturi | The Born-Oppenheimer approach to Quantum Cosmology | 21 pages, no figures | null | 10.1088/1361-6382/ac0a88 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The scope of this paper is to compare two different approaches for solving
the Wheeler-DeWitt (WDW) equation in the presence of homogeneous matter
(inflaton) and perturbations around it. The standard Born-Oppenheimer (BO)
decomposition, which consists of factorizing out the gravitational wave
function and then defining the flow of the time through it, and a more general
BO decomposition where the whole minisuperspace wave function is factorized
out. The two approaches are compared, for simplicity, in the case of a
minimally coupled inflaton with a flat potential. The consistency of the latter
decomposition is checked against the former by comparing the resulting
perturbation (Mukhanov-Sasaki) equations. Finally a few solutions to the
homogeneous WDW not suitable for the traditional BO treatment are presented and
the corresponding Mukhanov-Sasaki equations are evaluated.
| [
{
"created": "Thu, 29 Oct 2020 14:24:01 GMT",
"version": "v1"
}
] | 2021-08-11 | [
[
"Kamenshchik",
"A. Y.",
""
],
[
"Tronconi",
"A.",
""
],
[
"Venturi",
"G.",
""
]
] | The scope of this paper is to compare two different approaches for solving the Wheeler-DeWitt (WDW) equation in the presence of homogeneous matter (inflaton) and perturbations around it. The standard Born-Oppenheimer (BO) decomposition, which consists of factorizing out the gravitational wave function and then defining the flow of the time through it, and a more general BO decomposition where the whole minisuperspace wave function is factorized out. The two approaches are compared, for simplicity, in the case of a minimally coupled inflaton with a flat potential. The consistency of the latter decomposition is checked against the former by comparing the resulting perturbation (Mukhanov-Sasaki) equations. Finally a few solutions to the homogeneous WDW not suitable for the traditional BO treatment are presented and the corresponding Mukhanov-Sasaki equations are evaluated. |
0904.4318 | Leonardo Balart | Leonardo Balart | Energy distribution of 2+1 dimensional black holes with nonlinear
electrodynamics | 10 pages, no figures, references added | Mod.Phys.Lett.A24:2777-2785,2009 | 10.1142/S021773230903117X | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The energy distributions for a black hole solution resulting from coupling
electrodynamics and gravity in 2+1 dimensions are obtained. This solution
considers the correction for a 2+1 static charged black hole from the first
contribution of the weak field limit of one loop QED in 2+1 dimensions. The
Einstein and Moller energy-momentum prescriptions are used to evaluate the
energy distributions associated with the mentioned 2+1 dimensional black hole
and other 2+1 black hole solutions coupled with nonlinear electrodynamics. A
relation that connects the coefficients of both prescriptions is established.
| [
{
"created": "Tue, 28 Apr 2009 06:48:58 GMT",
"version": "v1"
},
{
"created": "Fri, 27 Nov 2009 03:55:17 GMT",
"version": "v2"
}
] | 2009-12-02 | [
[
"Balart",
"Leonardo",
""
]
] | The energy distributions for a black hole solution resulting from coupling electrodynamics and gravity in 2+1 dimensions are obtained. This solution considers the correction for a 2+1 static charged black hole from the first contribution of the weak field limit of one loop QED in 2+1 dimensions. The Einstein and Moller energy-momentum prescriptions are used to evaluate the energy distributions associated with the mentioned 2+1 dimensional black hole and other 2+1 black hole solutions coupled with nonlinear electrodynamics. A relation that connects the coefficients of both prescriptions is established. |
1807.07672 | Yasusada Nambu | Tomoro Tokusumi, Akira Matsumura and Yasusada Nambu | Quantum Circuit Model of Black Hole Evaporation | 26 pages, accepted version in CQG | Class. Quantum Grav. 35 (2018) 235013 | 10.1088/1361-6382/aaeb5a | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a quantum circuit model describing the evaporation process of
black holes. We specifically examine the behavior of the multipartite
entanglement represented by this model, and find that the entanglement
structure depends on the black hole mass $M$ and the frequency of the Hawking
radiation $\omega$. For sufficiently small values of $M\omega$, the black hole
and the radiation system becomes a separable state after the Page time and a
firewall-like structure appears. On the contrary, for larger values of
$M\omega$, the entanglement between the black hole and the radiation is not
lost. These behaviors imply that owing to the monogamy property of the
multipartite entanglement, low frequency modes of the Hawking radiation
destroys the quantum correlation between the black hole and the emitted Hawking
radiation.
| [
{
"created": "Fri, 20 Jul 2018 00:20:22 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Nov 2018 03:19:42 GMT",
"version": "v2"
}
] | 2018-11-14 | [
[
"Tokusumi",
"Tomoro",
""
],
[
"Matsumura",
"Akira",
""
],
[
"Nambu",
"Yasusada",
""
]
] | We consider a quantum circuit model describing the evaporation process of black holes. We specifically examine the behavior of the multipartite entanglement represented by this model, and find that the entanglement structure depends on the black hole mass $M$ and the frequency of the Hawking radiation $\omega$. For sufficiently small values of $M\omega$, the black hole and the radiation system becomes a separable state after the Page time and a firewall-like structure appears. On the contrary, for larger values of $M\omega$, the entanglement between the black hole and the radiation is not lost. These behaviors imply that owing to the monogamy property of the multipartite entanglement, low frequency modes of the Hawking radiation destroys the quantum correlation between the black hole and the emitted Hawking radiation. |
1404.2249 | Emmanuil Saridakis | Georgios Kofinas (Aegean U.), Emmanuel N. Saridakis (Natl. Tech. U.,
Athens and Valparaiso U., Catolica) | Teleparallel equivalent of Gauss-Bonnet gravity and its modifications | 10 pages, version to appear in Phys.Rev.D. The general equations of
motion have been derived, the cosmological applications are moved to a
separate publication | Phys. Rev. D 90, 084044 (2014) | 10.1103/PhysRevD.90.084044 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Inspired by the teleparallel formulation of General Relativity, whose
Lagrangian is the torsion invariant T, we have constructed the teleparallel
equivalent of Gauss-Bonnet gravity in arbitrary dimensions. Without imposing
the Weitzenbock connection, we have extracted the torsion invariant T_G,
equivalent (up to boundary terms) to the Gauss-Bonnet term G. T_G is
constructed by the vielbein and the connection, it contains quartic powers of
the torsion tensor, it is diffeomorphism and Lorentz invariant, and in four
dimensions it reduces to a topological invariant as expected. Imposing the
Weitzenbock connection, T_G depends only on the vielbein, and this allows us to
consider a novel class of modified gravity theories based on F(T,T_G), which is
not spanned by the class of F(T) theories, nor by the F(R,G) class of curvature
modified gravity. Finally, varying the action we extract the equations of
motion for F(T,T_G) gravity.
| [
{
"created": "Tue, 8 Apr 2014 18:52:21 GMT",
"version": "v1"
},
{
"created": "Thu, 31 Jul 2014 07:12:18 GMT",
"version": "v2"
},
{
"created": "Tue, 23 Sep 2014 13:53:36 GMT",
"version": "v3"
}
] | 2014-10-29 | [
[
"Kofinas",
"Georgios",
"",
"Aegean U."
],
[
"Saridakis",
"Emmanuel N.",
"",
"Natl. Tech. U.,\n Athens and Valparaiso U., Catolica"
]
] | Inspired by the teleparallel formulation of General Relativity, whose Lagrangian is the torsion invariant T, we have constructed the teleparallel equivalent of Gauss-Bonnet gravity in arbitrary dimensions. Without imposing the Weitzenbock connection, we have extracted the torsion invariant T_G, equivalent (up to boundary terms) to the Gauss-Bonnet term G. T_G is constructed by the vielbein and the connection, it contains quartic powers of the torsion tensor, it is diffeomorphism and Lorentz invariant, and in four dimensions it reduces to a topological invariant as expected. Imposing the Weitzenbock connection, T_G depends only on the vielbein, and this allows us to consider a novel class of modified gravity theories based on F(T,T_G), which is not spanned by the class of F(T) theories, nor by the F(R,G) class of curvature modified gravity. Finally, varying the action we extract the equations of motion for F(T,T_G) gravity. |
gr-qc/0105011 | Mauricio Bellini | Mauricio Bellini (IFM, Universidad Michoacana) | Decoherence of gauge-invariant metric fluctuations during inflation | version accepted in Phys. Rev. D | Phys.Rev. D64 (2001) 043507 | 10.1103/PhysRevD.64.043507 | null | gr-qc hep-ph | null | I study the gauge-invariant fluctuations of the metric during inflation. In
the infrared sector the metric fluctuations can be represented by a
coarse-grained field. We can write a Schroedinger equation for the
coarse-grained metric fluctuations which is related to an effective Hamiltonian
for a time dependent parameter of mass harmonic oscillator with a stochastic
external force. I study the wave function for a power-law expanding universe. I
find that the phase space of the quantum state for super Hubble scalar metric
perturbations loses its coherence at the end of inflation. This effect is a
consequence of interference between the super Hubble metric perturbations and
its canonical conjugate variable, which is produced by the interaction of the
coarse-grained scalar metric fluctuation with the environment.
| [
{
"created": "Wed, 2 May 2001 23:38:22 GMT",
"version": "v1"
},
{
"created": "Wed, 23 May 2001 22:51:25 GMT",
"version": "v2"
}
] | 2009-11-07 | [
[
"Bellini",
"Mauricio",
"",
"IFM, Universidad Michoacana"
]
] | I study the gauge-invariant fluctuations of the metric during inflation. In the infrared sector the metric fluctuations can be represented by a coarse-grained field. We can write a Schroedinger equation for the coarse-grained metric fluctuations which is related to an effective Hamiltonian for a time dependent parameter of mass harmonic oscillator with a stochastic external force. I study the wave function for a power-law expanding universe. I find that the phase space of the quantum state for super Hubble scalar metric perturbations loses its coherence at the end of inflation. This effect is a consequence of interference between the super Hubble metric perturbations and its canonical conjugate variable, which is produced by the interaction of the coarse-grained scalar metric fluctuation with the environment. |
2404.02972 | Konstantinos Dialektopoulos F. | Sebastian Bahamonde, Daniel Blixt, Konstantinos F. Dialektopoulos,
Anamaria Hell | Revisiting Stability in New General Relativity | 14 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the degrees of freedom in New General Relativity -- flat and metric
compatible family of theories -- around the Minkowski background in a gauge
invariant manner. First, we confirm the decoupling case, in which the theory
reduces to linearized gravity plus a massless KR field. We then show that,
unless they vanish, the vector modes of this theory will be ghosts. In
addition, we find two new branches of the theories, which are ghost-free and
propagate linearly two tensor modes and in one of the cases also a massless
scalar field. This shows that while the generic theory is ill-behaved, there
are three possible realizations of ghost-free cases, in contradiction to the
previous literature, which states that there is only one ghost-free theory in
addition to general relativity.
| [
{
"created": "Wed, 3 Apr 2024 18:00:17 GMT",
"version": "v1"
}
] | 2024-04-05 | [
[
"Bahamonde",
"Sebastian",
""
],
[
"Blixt",
"Daniel",
""
],
[
"Dialektopoulos",
"Konstantinos F.",
""
],
[
"Hell",
"Anamaria",
""
]
] | We study the degrees of freedom in New General Relativity -- flat and metric compatible family of theories -- around the Minkowski background in a gauge invariant manner. First, we confirm the decoupling case, in which the theory reduces to linearized gravity plus a massless KR field. We then show that, unless they vanish, the vector modes of this theory will be ghosts. In addition, we find two new branches of the theories, which are ghost-free and propagate linearly two tensor modes and in one of the cases also a massless scalar field. This shows that while the generic theory is ill-behaved, there are three possible realizations of ghost-free cases, in contradiction to the previous literature, which states that there is only one ghost-free theory in addition to general relativity. |
gr-qc/0102101 | Bahram Mashhoon | Lewis H. Ryder (University of Kent at Canterbury, UK), and Bahram
Mashhoon (University of Missouri-Columbia, USA) | Spin and Rotation in General Relativity | LaTeX file, no figures, 15 pages | null | 10.1007/3-540-40988-2_23 | null | gr-qc | null | Rapporteur's Introduction to the GT8 session of the Ninth Marcel Grossmann
Meeting (Rome, 2000); to appear in the Proceedings.
| [
{
"created": "Thu, 22 Feb 2001 22:00:06 GMT",
"version": "v1"
}
] | 2016-12-07 | [
[
"Ryder",
"Lewis H.",
"",
"University of Kent at Canterbury, UK"
],
[
"Mashhoon",
"Bahram",
"",
"University of Missouri-Columbia, USA"
]
] | Rapporteur's Introduction to the GT8 session of the Ninth Marcel Grossmann Meeting (Rome, 2000); to appear in the Proceedings. |
1712.07132 | Neil J. Cornish | Neil J. Cornish, Logan O'Beirne, Stephen R. Taylor and Nicolas Yunes | Constraining alternative theories of gravity using pulsar timing arrays | 5 pages, 4 figures | Phys. Rev. Lett. 120, 181101 (2018) | 10.1103/PhysRevLett.120.181101 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The opening of the gravitational wave window by ground-based laser
interferometers has made possible many new tests of gravity, including the
first constraints on polarization. It is hoped that within the next decade
pulsar timing will extend the window by making the first detections in the
nano-Hertz frequency regime. Pulsar timing offers several advantages over
ground-based interferometers for constraining the polarization of gravitational
waves due to the many projections of the polarization pattern provided by the
different lines of sight to the pulsars, and the enhanced response to
longitudinal polarizations. Here we show that existing results from pulsar
timing arrays can be used to place stringent limits on the energy density of
longitudinal stochastic gravitational waves. Paradoxically however, we find
that longitudinal modes will be very difficult to detect due to the large
variance in the pulsar-pulsar correlation patterns for these modes. Existing
upper limits on the power spectrum of pulsar timing residuals imply that the
amplitude of vector longitudinal and scalar longitudinal modes at frequencies
of 1/year are constrained: ${\cal A}_{\rm VL} < 4.1\times 10^{-16}$ and ${\cal
A}_{\rm SL} < 3.7\times 10^{-17}$, while the bounds on the energy density for a
scale invariant cosmological background are: $\Omega_{\rm VL}h^2 < 3.5 \times
10^{-11}$ and $\Omega_{\rm SL}h^2 < 3.2 \times 10^{-13}$.
| [
{
"created": "Tue, 19 Dec 2017 19:00:06 GMT",
"version": "v1"
}
] | 2018-05-09 | [
[
"Cornish",
"Neil J.",
""
],
[
"O'Beirne",
"Logan",
""
],
[
"Taylor",
"Stephen R.",
""
],
[
"Yunes",
"Nicolas",
""
]
] | The opening of the gravitational wave window by ground-based laser interferometers has made possible many new tests of gravity, including the first constraints on polarization. It is hoped that within the next decade pulsar timing will extend the window by making the first detections in the nano-Hertz frequency regime. Pulsar timing offers several advantages over ground-based interferometers for constraining the polarization of gravitational waves due to the many projections of the polarization pattern provided by the different lines of sight to the pulsars, and the enhanced response to longitudinal polarizations. Here we show that existing results from pulsar timing arrays can be used to place stringent limits on the energy density of longitudinal stochastic gravitational waves. Paradoxically however, we find that longitudinal modes will be very difficult to detect due to the large variance in the pulsar-pulsar correlation patterns for these modes. Existing upper limits on the power spectrum of pulsar timing residuals imply that the amplitude of vector longitudinal and scalar longitudinal modes at frequencies of 1/year are constrained: ${\cal A}_{\rm VL} < 4.1\times 10^{-16}$ and ${\cal A}_{\rm SL} < 3.7\times 10^{-17}$, while the bounds on the energy density for a scale invariant cosmological background are: $\Omega_{\rm VL}h^2 < 3.5 \times 10^{-11}$ and $\Omega_{\rm SL}h^2 < 3.2 \times 10^{-13}$. |
1907.04019 | Michael H\"orzinger | Hamed Barzegar, Piotr T. Chru\'sciel, Michael H\"orzinger, Maciej
Maliborski, Luc Nguyen | On the energy of the Horowitz-Myers metrics | null | Phys. Rev. D 101, 024007 (2020) | 10.1103/PhysRevD.101.024007 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present results supporting the Horowitz-Myers conjecture, that the
Horowitz-Myers metrics minimise energy in the relevant classes of metrics.
| [
{
"created": "Tue, 9 Jul 2019 07:19:22 GMT",
"version": "v1"
},
{
"created": "Tue, 28 Jan 2020 11:29:55 GMT",
"version": "v2"
}
] | 2020-01-29 | [
[
"Barzegar",
"Hamed",
""
],
[
"Chruściel",
"Piotr T.",
""
],
[
"Hörzinger",
"Michael",
""
],
[
"Maliborski",
"Maciej",
""
],
[
"Nguyen",
"Luc",
""
]
] | We present results supporting the Horowitz-Myers conjecture, that the Horowitz-Myers metrics minimise energy in the relevant classes of metrics. |
gr-qc/9808017 | Frank Gronwald | H.I.M. Lichtenegger, F. Gronwald, and B. Mashhoon | On detecting the gravitomagnetic field of the earth by means of orbiting
clocks | Talk given at the 32nd COSPAR Scientific Assembly, held at Nagoya,
Japan, 12-19 July 1998, 4 pages LATEX | null | null | null | gr-qc | null | Based on the recent finding that the difference in proper time of two clocks
in prograde and retrograde equatorial orbits about the Earth is of the order
10^{-7}s per revolution, the possibility of detecting the terrestrial
gravitomagnetic field by means of clocks carried by satellites is discussed. A
mission taking advantage of this influence of the rotating Earth on the proper
time is outlined and the conceptual difficulties are briefly examined.
| [
{
"created": "Wed, 5 Aug 1998 15:06:17 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Lichtenegger",
"H. I. M.",
""
],
[
"Gronwald",
"F.",
""
],
[
"Mashhoon",
"B.",
""
]
] | Based on the recent finding that the difference in proper time of two clocks in prograde and retrograde equatorial orbits about the Earth is of the order 10^{-7}s per revolution, the possibility of detecting the terrestrial gravitomagnetic field by means of clocks carried by satellites is discussed. A mission taking advantage of this influence of the rotating Earth on the proper time is outlined and the conceptual difficulties are briefly examined. |
gr-qc/9606034 | Takashi Torii | Takashi Torii, Hiroki Yajima and Kei-ichi Maeda | Dilatonic Black Holes with Gauss-Bonnet Term | 31pages, 11figures, LaTex style | Phys.Rev.D55:739-753,1997 | 10.1103/PhysRevD.55.739 | WU-AP/55/96 | gr-qc hep-th | null | We discuss black holes in an effective theory derived from a superstring
model, which includes a dilaton field, a gauge field and the Gauss-Bonnet term.
Assuming U(1) or SU(2) symmetry for the gauge field, we find four types of
spherically symmetric solutions, i.e., a neutral, an electrically charged, a
magnetically charged and a ``colored'' black hole, and discuss their
thermodynamical properties and fate via the Hawking evaporation process. For
neutral and electrically charged black holes, we find critical point and a
singular end point. Below the mass corresponding to the critical point,
nosolution exists, while the curvature on the horizon diverges and anaked
singularity appears at the singular point. A cusp structure in the mass-entropy
diagram is found at the critical point and black holes on the branch between
the critical and singular points become unstable. For magnetically charged and
``colored" black holes, the solution becomes singular just at the end point
with a finite mass. Because the black hole temperature is always finite even at
the critical point or the singular point, we may conclude that the evaporation
process will not be stopped even at the critical point or the singular point,
and the black hole will move to a dynamical evaporation phase or a naked
singularity will appear.
| [
{
"created": "Mon, 17 Jun 1996 04:12:46 GMT",
"version": "v1"
},
{
"created": "Wed, 19 Jun 1996 04:18:00 GMT",
"version": "v2"
}
] | 2010-11-19 | [
[
"Torii",
"Takashi",
""
],
[
"Yajima",
"Hiroki",
""
],
[
"Maeda",
"Kei-ichi",
""
]
] | We discuss black holes in an effective theory derived from a superstring model, which includes a dilaton field, a gauge field and the Gauss-Bonnet term. Assuming U(1) or SU(2) symmetry for the gauge field, we find four types of spherically symmetric solutions, i.e., a neutral, an electrically charged, a magnetically charged and a ``colored'' black hole, and discuss their thermodynamical properties and fate via the Hawking evaporation process. For neutral and electrically charged black holes, we find critical point and a singular end point. Below the mass corresponding to the critical point, nosolution exists, while the curvature on the horizon diverges and anaked singularity appears at the singular point. A cusp structure in the mass-entropy diagram is found at the critical point and black holes on the branch between the critical and singular points become unstable. For magnetically charged and ``colored" black holes, the solution becomes singular just at the end point with a finite mass. Because the black hole temperature is always finite even at the critical point or the singular point, we may conclude that the evaporation process will not be stopped even at the critical point or the singular point, and the black hole will move to a dynamical evaporation phase or a naked singularity will appear. |
gr-qc/0201095 | Christoph Schmid | Christoph Schmid (ETH Zurich) | Cosmological Vorticity Perturbations, Gravitomagnetism, and Mach's
Principle | 10 pages, to appear in Proc. COSMO-01, Rovaniemi, Finland, Aug 29 -
Sep 4, 2001 | null | null | null | gr-qc astro-ph | null | The axes of gyroscopes experimentally define non-rotating frames.
But what physical cause governs the time-evolution of gyroscope axes?
Starting from an unperturbed, spatially flat FRW cosmology, we consider
cosmological vorticity perturbations (i.e. vector perturbations, rotational
perturbations) at the linear level. We ask: Will cosmological rotational
perturbations drag the axis of a gyroscope relative to the directions
(geodesics) to galaxies beyond the rotational perturbation? We cast the laws of
Gravitomagnetism into a form showing clearly the close correspondence with the
laws of ordinary magnetism. Our results are: 1) The dragging of a gyroscope
axis by rotational perturbations beyond the $\dot{H}$ radius (H = Hubble
constant) is exponentially suppressed. 2) If the perturbation is a homogeneous
rotation inside a radius significantly larger than the $\dot{H}$ radius, then
the dragging of the gyroscope axis by the rotational perturbation is exact for
any equation of state for cosmological matter. 3) The time-evolution of a
gyroscope axis exactly follows a specific average of the matter inside the
$\dot{H}$ radius for any equation of state. In this precise sense Mach's
Principle follows from cosmology with Einstein Gravity.
| [
{
"created": "Wed, 30 Jan 2002 13:52:42 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Schmid",
"Christoph",
"",
"ETH Zurich"
]
] | The axes of gyroscopes experimentally define non-rotating frames. But what physical cause governs the time-evolution of gyroscope axes? Starting from an unperturbed, spatially flat FRW cosmology, we consider cosmological vorticity perturbations (i.e. vector perturbations, rotational perturbations) at the linear level. We ask: Will cosmological rotational perturbations drag the axis of a gyroscope relative to the directions (geodesics) to galaxies beyond the rotational perturbation? We cast the laws of Gravitomagnetism into a form showing clearly the close correspondence with the laws of ordinary magnetism. Our results are: 1) The dragging of a gyroscope axis by rotational perturbations beyond the $\dot{H}$ radius (H = Hubble constant) is exponentially suppressed. 2) If the perturbation is a homogeneous rotation inside a radius significantly larger than the $\dot{H}$ radius, then the dragging of the gyroscope axis by the rotational perturbation is exact for any equation of state for cosmological matter. 3) The time-evolution of a gyroscope axis exactly follows a specific average of the matter inside the $\dot{H}$ radius for any equation of state. In this precise sense Mach's Principle follows from cosmology with Einstein Gravity. |
1208.1913 | Mohammad Nouri-Zonoz | M. Nouri-Zonoz, H. Ramezani-Aval and R. Gharechahi | On Franklin's relativistic rotational transformation and its
modification | 30 pages, 2 figures, replaced with the published version | Eur. Phys. J. C (2014) 74:3098 | 10.1140/epjc/s10052-014-3098-6 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Unlike the Lorentz transformation which replaces the Galilean transformation
among inertial frames at high relative velocities, there seems to be no such a
consensus in the case of coordinate transformation between inertial frames and
uniformly rotating ones. There have been some attempts to generalize the
Galilean rotational transformation to high rotational velocities. Here we
introduce a modified version of one of these transformations proposed by Philip
Franklin in 1922. The modified version is shown to resolve some of the
drawbacks of the Franklin transformation, specially with respect to the
corresponding spacetime metric in the rotating frame. This new transformation
introduces non-inertial eccentric observers on a uniformly rotating disk and
the corresponding metric in the rotating frame is shown to be consistent with
the one obtained through Galilean rotational transformation for points close to
the rotation axis. Employing the threading formulation of spacetime
decomposition, spatial distances and time intervals in the spacetime metric of
a rotating observer's frame are also discussed.
| [
{
"created": "Thu, 9 Aug 2012 13:53:13 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Jul 2013 11:38:56 GMT",
"version": "v2"
},
{
"created": "Sat, 5 Apr 2014 07:27:56 GMT",
"version": "v3"
},
{
"created": "Thu, 18 Dec 2014 13:46:31 GMT",
"version": "v4"
}
] | 2014-12-23 | [
[
"Nouri-Zonoz",
"M.",
""
],
[
"Ramezani-Aval",
"H.",
""
],
[
"Gharechahi",
"R.",
""
]
] | Unlike the Lorentz transformation which replaces the Galilean transformation among inertial frames at high relative velocities, there seems to be no such a consensus in the case of coordinate transformation between inertial frames and uniformly rotating ones. There have been some attempts to generalize the Galilean rotational transformation to high rotational velocities. Here we introduce a modified version of one of these transformations proposed by Philip Franklin in 1922. The modified version is shown to resolve some of the drawbacks of the Franklin transformation, specially with respect to the corresponding spacetime metric in the rotating frame. This new transformation introduces non-inertial eccentric observers on a uniformly rotating disk and the corresponding metric in the rotating frame is shown to be consistent with the one obtained through Galilean rotational transformation for points close to the rotation axis. Employing the threading formulation of spacetime decomposition, spatial distances and time intervals in the spacetime metric of a rotating observer's frame are also discussed. |
gr-qc/0303069 | Jose A. Gonzalez | Miguel Alcubierre, Alejandro Corichi, Jose A. Gonzalez, Dario Nunez
and Marcelo Salgado | A hyperbolic slicing condition adapted to Killing fields and densitized
lapses | 11 pages | Class.Quant.Grav. 20 (2003) 3951-3968 | 10.1088/0264-9381/20/18/308 | null | gr-qc | null | We study the properties of a modified version of the Bona-Masso family of
hyperbolic slicing conditions. This modified slicing condition has two very
important features: In the first place, it guarantees that if a spacetime is
static or stationary, and one starts the evolution in a coordinate system in
which the metric coefficients are already time independent, then they will
remain time independent during the subsequent evolution, {\em i.e.} the lapse
will not evolve and will therefore not drive the time lines away from the
Killing direction. Second, the modified condition is naturally adapted to the
use of a densitized lapse as a fundamental variable, which in turn makes it a
good candidate for a dynamic slicing condition that can be used in conjunction
with some recently proposed hyperbolic reformulations of the Einstein evolution
equations.
| [
{
"created": "Tue, 18 Mar 2003 20:00:06 GMT",
"version": "v1"
},
{
"created": "Tue, 26 Aug 2003 13:58:58 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Alcubierre",
"Miguel",
""
],
[
"Corichi",
"Alejandro",
""
],
[
"Gonzalez",
"Jose A.",
""
],
[
"Nunez",
"Dario",
""
],
[
"Salgado",
"Marcelo",
""
]
] | We study the properties of a modified version of the Bona-Masso family of hyperbolic slicing conditions. This modified slicing condition has two very important features: In the first place, it guarantees that if a spacetime is static or stationary, and one starts the evolution in a coordinate system in which the metric coefficients are already time independent, then they will remain time independent during the subsequent evolution, {\em i.e.} the lapse will not evolve and will therefore not drive the time lines away from the Killing direction. Second, the modified condition is naturally adapted to the use of a densitized lapse as a fundamental variable, which in turn makes it a good candidate for a dynamic slicing condition that can be used in conjunction with some recently proposed hyperbolic reformulations of the Einstein evolution equations. |
1804.11219 | Dag {\O}stvang | Dag {\O}stvang | Fully Extended Quasi-Metric Gravity | 20 pages; v2: somewhat extended; v3: major revision (title changed);
v4: somewhat revised and extended; v5: further revised; v6: inconsistent
equation replaced arXiv admin note: text overlap with arXiv:gr-qc/0112025 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The original theory of quasi-metric gravity, admitting only a partial
coupling between space-time geometry and the active stress-energy tensor, is
too restricted to allow the existence of gravitational waves in vacuum.
Therefore, said theory can at best be regarded as a wave-less approximation
theory. However, the requirement that the weak-field limit of the contracted
Bianchi identities should be consistent with the Newtonian limit of the local
conservation laws, forbids a full coupling between space-time geometry and the
active stress-energy tensor. Nevertheless, in this paper it is shown how it is
possible to relax the restrictions on quasi-metric space-time geometry
sufficiently to avoid these problems. That is, the original quasi-metric field
equations can be extended with one extra field equation, without having said
full coupling and such that the contracted Bianchi identities have a sensible
Newtonian limit. For weak fields in vacuum, said extra field equation has a
dynamical structure somewhat similar to that of its counterpart in canonical
general relativity (GR). In this way, the prediction of weak GR-like
gravitational waves in vacuum becomes possible. Moreover, exact results from
the original quasi-metric gravitational theory are recovered for metrically
static systems and for isotropic cosmology. This means that the current
experimental status of the extended quasi-metric gravitational theory is the
same as for the original theory, except for the prediction of weak GR-like
gravitational waves in vacuum.
| [
{
"created": "Mon, 30 Apr 2018 14:12:52 GMT",
"version": "v1"
},
{
"created": "Thu, 22 Nov 2018 21:58:52 GMT",
"version": "v2"
},
{
"created": "Tue, 31 Dec 2019 13:45:52 GMT",
"version": "v3"
},
{
"created": "Wed, 30 Dec 2020 23:20:32 GMT",
"version": "v4"
},
{
"c... | 2024-03-19 | [
[
"Østvang",
"Dag",
""
]
] | The original theory of quasi-metric gravity, admitting only a partial coupling between space-time geometry and the active stress-energy tensor, is too restricted to allow the existence of gravitational waves in vacuum. Therefore, said theory can at best be regarded as a wave-less approximation theory. However, the requirement that the weak-field limit of the contracted Bianchi identities should be consistent with the Newtonian limit of the local conservation laws, forbids a full coupling between space-time geometry and the active stress-energy tensor. Nevertheless, in this paper it is shown how it is possible to relax the restrictions on quasi-metric space-time geometry sufficiently to avoid these problems. That is, the original quasi-metric field equations can be extended with one extra field equation, without having said full coupling and such that the contracted Bianchi identities have a sensible Newtonian limit. For weak fields in vacuum, said extra field equation has a dynamical structure somewhat similar to that of its counterpart in canonical general relativity (GR). In this way, the prediction of weak GR-like gravitational waves in vacuum becomes possible. Moreover, exact results from the original quasi-metric gravitational theory are recovered for metrically static systems and for isotropic cosmology. This means that the current experimental status of the extended quasi-metric gravitational theory is the same as for the original theory, except for the prediction of weak GR-like gravitational waves in vacuum. |
2306.14439 | Kun Zhou | Kun Zhou, Jun Cheng, and Liangliang Ren | Detecting anisotropies of the stochastic gravitational wave background
with TianQin | 27 pages, 9 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The investigation of the anisotropy of the stochastic gravitational wave
background (SGWB) using the TianQin detector plays a crucial role in studying
the early universe and astrophysics. In this work, we examine the response of
the $AET$ channel of the TianQin Time Delay Interferometry (TDI) to the
anisotropy of the SGWB. We calculate the corresponding angular sensitivity
curves and find that TianQin is capable of detecting the anisotropy of the
SGWB, with an angular sensitivity reaching $10^{-10}$ for quadrupoles. Due to
the fixed $z$-axis of TianQin pointing towards J0806, its overlap reduction
functions (ORFs) exhibit specific symmetries, enabling the resolution of
different multipole moments $\ell m$. The detection sensitivity is optimal for
the $(2, 0)$ mode, with a sensitivity reaching $10^{-10}$. Using the Fisher
matrix approach, we estimate the parameters and find that in the power-law
spectrum model, higher logarithmic amplitudes lead to more effective
reconstruction of the spectral index for all multipole moments. Under the
optimal scenario with a signal amplitude of $\Omega_{\mathrm{GW}} (f =
f_{\mathrm{c}}) h^2 = 10^{-9}$, the spectral indices can be reconstructed with
uncertainties of $10^{-3}$, $10$, and $10^{-3}$ for $\ell = 0$, $1$, and $2$
multipole moments, respectively. For the cases of $(\ell, m) = (0, 0)$, $(1,
1)$, $(2, 0)$, and $(2, 2)$, the spectral indices can be reconstructed with
uncertainties of $10^{-3}$, $10$, $10^{-3}$, and $10$, respectively.
| [
{
"created": "Mon, 26 Jun 2023 06:09:50 GMT",
"version": "v1"
},
{
"created": "Tue, 27 Jun 2023 05:03:58 GMT",
"version": "v2"
},
{
"created": "Tue, 4 Jul 2023 15:28:58 GMT",
"version": "v3"
}
] | 2023-07-06 | [
[
"Zhou",
"Kun",
""
],
[
"Cheng",
"Jun",
""
],
[
"Ren",
"Liangliang",
""
]
] | The investigation of the anisotropy of the stochastic gravitational wave background (SGWB) using the TianQin detector plays a crucial role in studying the early universe and astrophysics. In this work, we examine the response of the $AET$ channel of the TianQin Time Delay Interferometry (TDI) to the anisotropy of the SGWB. We calculate the corresponding angular sensitivity curves and find that TianQin is capable of detecting the anisotropy of the SGWB, with an angular sensitivity reaching $10^{-10}$ for quadrupoles. Due to the fixed $z$-axis of TianQin pointing towards J0806, its overlap reduction functions (ORFs) exhibit specific symmetries, enabling the resolution of different multipole moments $\ell m$. The detection sensitivity is optimal for the $(2, 0)$ mode, with a sensitivity reaching $10^{-10}$. Using the Fisher matrix approach, we estimate the parameters and find that in the power-law spectrum model, higher logarithmic amplitudes lead to more effective reconstruction of the spectral index for all multipole moments. Under the optimal scenario with a signal amplitude of $\Omega_{\mathrm{GW}} (f = f_{\mathrm{c}}) h^2 = 10^{-9}$, the spectral indices can be reconstructed with uncertainties of $10^{-3}$, $10$, and $10^{-3}$ for $\ell = 0$, $1$, and $2$ multipole moments, respectively. For the cases of $(\ell, m) = (0, 0)$, $(1, 1)$, $(2, 0)$, and $(2, 2)$, the spectral indices can be reconstructed with uncertainties of $10^{-3}$, $10$, $10^{-3}$, and $10$, respectively. |
1012.0458 | Jose M. Martin-Garcia | Yvonne Choquet-Bruhat, Jos\'e M. Mart\'in-Garc\'ia | Energy estimate for initial data on a characteristic cone | 11 pages. Contribution to the proceedings of the conference "New
Developments in Lorentzian Geometry", held in Berlin, Nov 2009 | null | null | null | gr-qc math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Einstein equations in wave map gauge are a geometric second order system
for a Lorentzian metric. To study existence of solutions of this hyperbolic
quasi diagonal system with initial data on a characteristic cone which are not
zero in a neighbourhood of the vertex one can appeal to theorems due to Cagnac
and Dossa, proved for a scalar wave equation, for initial data in functional
spaces relevant for their proofs. It is difficult to check that the initial
data that we have constructed as solutions of the Einstein wave-map gauge
constraints satisfy the more general of the Cagnac-Dossa hypotheses which uses
weighted energy estimates. In this paper we start a new study of energy
estimates using on the cone coordinates adapted to its null structure which are
precisely the coordinates used to solve the constraints, following work of
Rendall who considered the Cauchy problem for Einstein equations with data on
two intersecting characteristic surfaces.
| [
{
"created": "Thu, 2 Dec 2010 15:45:48 GMT",
"version": "v1"
}
] | 2016-08-14 | [
[
"Choquet-Bruhat",
"Yvonne",
""
],
[
"Martín-García",
"José M.",
""
]
] | The Einstein equations in wave map gauge are a geometric second order system for a Lorentzian metric. To study existence of solutions of this hyperbolic quasi diagonal system with initial data on a characteristic cone which are not zero in a neighbourhood of the vertex one can appeal to theorems due to Cagnac and Dossa, proved for a scalar wave equation, for initial data in functional spaces relevant for their proofs. It is difficult to check that the initial data that we have constructed as solutions of the Einstein wave-map gauge constraints satisfy the more general of the Cagnac-Dossa hypotheses which uses weighted energy estimates. In this paper we start a new study of energy estimates using on the cone coordinates adapted to its null structure which are precisely the coordinates used to solve the constraints, following work of Rendall who considered the Cauchy problem for Einstein equations with data on two intersecting characteristic surfaces. |
gr-qc/0503106 | Ian H. Redmount | Ian H. Redmount (Parks College of Engineering, Aviation, and
Technology, Saint Louis University, St. Louis, Missouri USA) | Localized Particle States and Dynamics Gravitational Effects | 12 pages, 5 figures | Phys.Rev. D73 (2006) 044032 | 10.1103/PhysRevD.73.044032 | null | gr-qc | null | Scalar particles--i.e., scalar-field excitations--in de Sitter space exhibit
behavior unlike either classical particles in expanding space or quantum
particles in flat spacetime. Their energies oscillate forever, and their
interactions are spread out in energy. Here it is shown that these features
characterize not only normal-mode excitations spread out over all space, but
localized particles or wave packets as well. Both one-particle and coherent
states of a massive, minimally coupled scalar field in de Sitter space,
associated with classical wave packets, are constructed explicitly. Their
energy expectation values and corresponding Unruh-DeWitt detector response
functions are calculated. Numerical evaluation of these quantities for a simple
set of classical wave packets clearly displays these novel features. Hence,
given the observed accelerating expansion of the Universe, it is possible that
observation of an ultralow-mass scalar particle could yield direct confirmation
of distinct predictions of quantum field theory in curved spacetime.
| [
{
"created": "Fri, 25 Mar 2005 00:30:23 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Redmount",
"Ian H.",
"",
"Parks College of Engineering, Aviation, and\n Technology, Saint Louis University, St. Louis, Missouri USA"
]
] | Scalar particles--i.e., scalar-field excitations--in de Sitter space exhibit behavior unlike either classical particles in expanding space or quantum particles in flat spacetime. Their energies oscillate forever, and their interactions are spread out in energy. Here it is shown that these features characterize not only normal-mode excitations spread out over all space, but localized particles or wave packets as well. Both one-particle and coherent states of a massive, minimally coupled scalar field in de Sitter space, associated with classical wave packets, are constructed explicitly. Their energy expectation values and corresponding Unruh-DeWitt detector response functions are calculated. Numerical evaluation of these quantities for a simple set of classical wave packets clearly displays these novel features. Hence, given the observed accelerating expansion of the Universe, it is possible that observation of an ultralow-mass scalar particle could yield direct confirmation of distinct predictions of quantum field theory in curved spacetime. |
gr-qc/0106080 | Pisin Chen | Ronald J. Adler, Pisin Chen, David I. Santiago | The Generalized Uncertainty Principle and Black Hole Remnants | 11 pages, 4 figures; Winner of 3rd Place in the 2001 Gravity Research
Foundation Essay Competition | Gen.Rel.Grav. 33 (2001) 2101-2108 | 10.1023/A:1015281430411 | SLAC-PUB-8853 (June, 2001) | gr-qc | null | In the current standard viewpoint small black holes are believed to emit
radiation as black bodies at the Hawking temperature, at least until they reach
Planck size, after which their fate is open to conjecture. A cogent argument
against the existence of remnants is that, since no evident quantum number
prevents it, black holes should radiate completely away to photons and other
ordinary stable particles and vacuum, like any unstable quantum system. Here we
argue the contrary, that the generalized uncertainty principle may prevent
their total evaporation in exactly the same way that the uncertainty principle
prevents the hydrogen atom from total collapse: the collapse is prevented, not
by symmetry, but by dynamics, as a minimum size and mass are approached.
| [
{
"created": "Tue, 26 Jun 2001 00:09:55 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Adler",
"Ronald J.",
""
],
[
"Chen",
"Pisin",
""
],
[
"Santiago",
"David I.",
""
]
] | In the current standard viewpoint small black holes are believed to emit radiation as black bodies at the Hawking temperature, at least until they reach Planck size, after which their fate is open to conjecture. A cogent argument against the existence of remnants is that, since no evident quantum number prevents it, black holes should radiate completely away to photons and other ordinary stable particles and vacuum, like any unstable quantum system. Here we argue the contrary, that the generalized uncertainty principle may prevent their total evaporation in exactly the same way that the uncertainty principle prevents the hydrogen atom from total collapse: the collapse is prevented, not by symmetry, but by dynamics, as a minimum size and mass are approached. |
2206.12744 | Mikhail Zubkov Dr | S.Bondarenko, M.A.Zubkov | Riemann-Cartan gravity with dynamical signature | Latex, 7 pages | Jetp Lett. (2022) | 10.1134/S0021364022601002 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Model of Riemann-Cartan gravity with varying signature of metric is
considered. The basic dynamical variables of the formalism are vierbein, spin
connection, and an internal metric in the tangent space. The corresponding
action contains new terms, which depend on these fields. In general case the
signature of the metric is determined dynamically. The Minkowski signature is
preferred dynamically because the configurations with the other signatures are
dynamically suppressed. We also discuss briefly the motion of particles in the
background of the modified black hole configuration, in which inside the
horizon the signature is that of Euclidean space - time.
| [
{
"created": "Sat, 25 Jun 2022 22:28:18 GMT",
"version": "v1"
}
] | 2022-06-28 | [
[
"Bondarenko",
"S.",
""
],
[
"Zubkov",
"M. A.",
""
]
] | Model of Riemann-Cartan gravity with varying signature of metric is considered. The basic dynamical variables of the formalism are vierbein, spin connection, and an internal metric in the tangent space. The corresponding action contains new terms, which depend on these fields. In general case the signature of the metric is determined dynamically. The Minkowski signature is preferred dynamically because the configurations with the other signatures are dynamically suppressed. We also discuss briefly the motion of particles in the background of the modified black hole configuration, in which inside the horizon the signature is that of Euclidean space - time. |
2407.07688 | Shu-Min Wu | Wen-Mei Li, Shu-Min Wu | Bosonic and fermionic coherence of N-partite states in the background of
a dilaton black hole | 23 pages, 5 figures, | null | null | null | gr-qc quant-ph | http://creativecommons.org/licenses/by/4.0/ | We study the N-partite coherences of GHZ and W states for free bosonic and
fermionic fields when any n observers hover near the event horizon of a
Garfinkle-Horowitz-Strominger (GHS) dilaton black hole. We derive the more
general analytical expressions for N-partite coherence, encompassing both
physically accessible and inaccessible coherences in the context of the dilaton
black hole. It has been found that the coherence of the bosonic field is
greater than that of the fermionic field, while the entanglement of the
fermionic field is greater than that of the bosonic field in dilaton spacetime.
Additionally, the coherence of the W state is greater than that of the GHZ
state, whereas the entanglement of the GHZ state is greater than that of the W
state in curved spacetime. These results suggest that we should utilize
suitable quantum resources and different types of particles for relativistic
quantum information tasks.
| [
{
"created": "Wed, 10 Jul 2024 14:10:30 GMT",
"version": "v1"
}
] | 2024-07-11 | [
[
"Li",
"Wen-Mei",
""
],
[
"Wu",
"Shu-Min",
""
]
] | We study the N-partite coherences of GHZ and W states for free bosonic and fermionic fields when any n observers hover near the event horizon of a Garfinkle-Horowitz-Strominger (GHS) dilaton black hole. We derive the more general analytical expressions for N-partite coherence, encompassing both physically accessible and inaccessible coherences in the context of the dilaton black hole. It has been found that the coherence of the bosonic field is greater than that of the fermionic field, while the entanglement of the fermionic field is greater than that of the bosonic field in dilaton spacetime. Additionally, the coherence of the W state is greater than that of the GHZ state, whereas the entanglement of the GHZ state is greater than that of the W state in curved spacetime. These results suggest that we should utilize suitable quantum resources and different types of particles for relativistic quantum information tasks. |
1705.05740 | Christopher Pope | M. Cvetic, G.W. Gibbons and C.N. Pope | STU Black Holes and SgrA* | 20 pages | null | 10.1088/1475-7516/2017/08/016 | UPR-1284-T, MI-TH-1751 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The equations of null geodesics in the STU family of rotating black hole
solutions of supergravity theory, which may be considered as deformations of
the vacuum Kerr metric, are completely integrable. We propose that they be used
as a foil to test, for example, with what precision the gravitational field
external to the black hole at the centre of our galaxy is given by the Kerr
metric. By contrast with some metrics proposed in the literature, the STU
metrics satisfy by construction the dominant and strong energy conditions. Our
considerations may be extended to include the effects of a cosmological term.
We show that these metrics permit a straightforward calculation of the
properties of black hole shadows.
| [
{
"created": "Tue, 16 May 2017 14:51:59 GMT",
"version": "v1"
}
] | 2019-04-26 | [
[
"Cvetic",
"M.",
""
],
[
"Gibbons",
"G. W.",
""
],
[
"Pope",
"C. N.",
""
]
] | The equations of null geodesics in the STU family of rotating black hole solutions of supergravity theory, which may be considered as deformations of the vacuum Kerr metric, are completely integrable. We propose that they be used as a foil to test, for example, with what precision the gravitational field external to the black hole at the centre of our galaxy is given by the Kerr metric. By contrast with some metrics proposed in the literature, the STU metrics satisfy by construction the dominant and strong energy conditions. Our considerations may be extended to include the effects of a cosmological term. We show that these metrics permit a straightforward calculation of the properties of black hole shadows. |
1812.01559 | Seema Satin | Seema Satin | Stochastic metric perturbations (radial) in gravitationally collapsing
spherically symmetric relativistic star | null | Gen Relativ Gravit (2019) 51: 52 | 10.1007/s10714-019-2536-z | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Stochastic perturbations (radial) of a spherically symmetric relativistic
star, modeled by a perfect fluid in comoving coordinates for the collapse
scenario are worked out using the classical Einstein- Langevin equation, which
has been proposed recently. The solutions are in terms of perturbed metric
potentials and their two point correlation. For the case worked out here, it is
interesting to note that the two perturbed metric potentials have same
magnitude, while the potentials themselves are in general independent of each
other. Such a treatment is useful for building up basic theory of
non-equilibrium and near equilibrium statistical physics for collapsing stars,
which should be of interest towards the end states of collapse. Here we discuss
the first simple model, that of non-rotating spherically symmetric dynamically
collapsing relativistic star. This paves way to further research on rotating
collapse models of isolated as well as binary configurations on similar lines .
Both the radial and non-radial perturbations with stochastic effects would be
of interest to asteroseismology, which encompassed the future plan of study.
| [
{
"created": "Tue, 4 Dec 2018 17:56:28 GMT",
"version": "v1"
},
{
"created": "Thu, 28 Mar 2019 05:54:40 GMT",
"version": "v2"
}
] | 2019-04-09 | [
[
"Satin",
"Seema",
""
]
] | Stochastic perturbations (radial) of a spherically symmetric relativistic star, modeled by a perfect fluid in comoving coordinates for the collapse scenario are worked out using the classical Einstein- Langevin equation, which has been proposed recently. The solutions are in terms of perturbed metric potentials and their two point correlation. For the case worked out here, it is interesting to note that the two perturbed metric potentials have same magnitude, while the potentials themselves are in general independent of each other. Such a treatment is useful for building up basic theory of non-equilibrium and near equilibrium statistical physics for collapsing stars, which should be of interest towards the end states of collapse. Here we discuss the first simple model, that of non-rotating spherically symmetric dynamically collapsing relativistic star. This paves way to further research on rotating collapse models of isolated as well as binary configurations on similar lines . Both the radial and non-radial perturbations with stochastic effects would be of interest to asteroseismology, which encompassed the future plan of study. |
gr-qc/9909087 | Steven Carlip | S. Carlip | Aberration and the Speed of Gravity | 9 pages, LaTeX, one figure using LaTeX picture environment;
references added, abstract shortened, typos corrected, discussion of
aberration and radiation reaction amplified; no change in essential argument | Phys.Lett.A267:81-87,2000 | 10.1016/S0375-9601(00)00101-8 | UCD-99-17 | gr-qc | null | The observed absence of gravitational aberration requires that ``Newtonian''
gravity propagate at a speed $c_g>2\times10^{10}c$. By evaluating the
gravitational effect of an accelerating mass, I show that aberration in general
relativity is almost exactly canceled by velocity-dependent interactions,
permitting $c_g=c$. This cancellation is dictated by conservation laws and the
quadrupole nature of gravitational radiation.
| [
{
"created": "Wed, 29 Sep 1999 19:38:40 GMT",
"version": "v1"
},
{
"created": "Fri, 31 Dec 1999 22:19:19 GMT",
"version": "v2"
}
] | 2010-04-28 | [
[
"Carlip",
"S.",
""
]
] | The observed absence of gravitational aberration requires that ``Newtonian'' gravity propagate at a speed $c_g>2\times10^{10}c$. By evaluating the gravitational effect of an accelerating mass, I show that aberration in general relativity is almost exactly canceled by velocity-dependent interactions, permitting $c_g=c$. This cancellation is dictated by conservation laws and the quadrupole nature of gravitational radiation. |
2304.05384 | Alex Va\~n\'o-Vi\~nuales | Alex Va\~n\'o-Vi\~nuales | Spherically symmetric black hole spacetimes on hyperboloidal slices | 28 pages, 15 figures, matches published version | Frontiers in Applied Mathematics and Statistics, Sec. Statistical
and Computational Physics, Volume 9 (2023) | 10.3389/fams.2023.1206017 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Gravitational radiation and some global properties of spacetimes can only be
unambiguously measured at future null infinity . This motivates the interest in
reaching it within simulations of coalescing compact objects, whose waveforms
are extracted for gravitational wave modelling purposes. One promising method
to include future null infinity in the numerical domain is the evolution on
hyperboloidal slices: smooth spacelike slices that reach future null infinity.
The main challenge in this approach is the treatment of the compactified
asymptotic region at future null infinity. Evolution on a hyperboloidal slice
of a spacetime including a black hole entails an extra layer of difficulty, in
part due to the finite coordinate distance between the black hole and future
null infinity. Spherical symmetry is considered here as simplest setup still
encompassing the full complication of the treatment along the radial
coordinate. First, the construction of constant-mean-curvature hyperboloidal
trumpet slices for Schwarzschild and Reissner-Nordstr\"om black hole spacetimes
is reviewed from the point of view of the puncture approach. Then, the
framework is set for solving hyperboloidal-adapted hyperbolic gauge conditions
for stationary trumpet initial data, providing solutions for two specific sets
of parameters. Finally, results of testing these initial data in evolution are
presented.
| [
{
"created": "Tue, 11 Apr 2023 17:54:34 GMT",
"version": "v1"
},
{
"created": "Tue, 22 Aug 2023 18:07:26 GMT",
"version": "v2"
}
] | 2023-08-24 | [
[
"Vañó-Viñuales",
"Alex",
""
]
] | Gravitational radiation and some global properties of spacetimes can only be unambiguously measured at future null infinity . This motivates the interest in reaching it within simulations of coalescing compact objects, whose waveforms are extracted for gravitational wave modelling purposes. One promising method to include future null infinity in the numerical domain is the evolution on hyperboloidal slices: smooth spacelike slices that reach future null infinity. The main challenge in this approach is the treatment of the compactified asymptotic region at future null infinity. Evolution on a hyperboloidal slice of a spacetime including a black hole entails an extra layer of difficulty, in part due to the finite coordinate distance between the black hole and future null infinity. Spherical symmetry is considered here as simplest setup still encompassing the full complication of the treatment along the radial coordinate. First, the construction of constant-mean-curvature hyperboloidal trumpet slices for Schwarzschild and Reissner-Nordstr\"om black hole spacetimes is reviewed from the point of view of the puncture approach. Then, the framework is set for solving hyperboloidal-adapted hyperbolic gauge conditions for stationary trumpet initial data, providing solutions for two specific sets of parameters. Finally, results of testing these initial data in evolution are presented. |
gr-qc/0312089 | Seth A. Major | Dan Heyman, Franz Hinteleitner, Seth Major | On reaction thresholds in doubly special relativity | 13 pages,v3 added comments regarding the assumption of composite
particles,minor wording changes, version to be published | Phys.Rev. D69 (2004) 105016 | 10.1103/PhysRevD.69.105016 | null | gr-qc | null | Two theories of special relativity with an additional invariant scale,
"doubly special relativity" (DSR), are tested with calculations of particle
process kinematics. Using the Judes-Visser modified conservation laws,
thresholds are studied in both theories. In contrast to some linear
approximations, which allow for particle processes forbidden in special
relativity, both the Amelino-Camelia and Maguejo-Smolin frameworks allow no
additional processes. To first order, the Amelino-Camelia framework thresholds
are lowered and the Maguejo-Smolin framework thresholds may be raised or
lowered.
| [
{
"created": "Fri, 19 Dec 2003 16:44:16 GMT",
"version": "v1"
},
{
"created": "Fri, 16 Jan 2004 15:10:35 GMT",
"version": "v2"
},
{
"created": "Mon, 29 Mar 2004 19:59:00 GMT",
"version": "v3"
}
] | 2009-11-10 | [
[
"Heyman",
"Dan",
""
],
[
"Hinteleitner",
"Franz",
""
],
[
"Major",
"Seth",
""
]
] | Two theories of special relativity with an additional invariant scale, "doubly special relativity" (DSR), are tested with calculations of particle process kinematics. Using the Judes-Visser modified conservation laws, thresholds are studied in both theories. In contrast to some linear approximations, which allow for particle processes forbidden in special relativity, both the Amelino-Camelia and Maguejo-Smolin frameworks allow no additional processes. To first order, the Amelino-Camelia framework thresholds are lowered and the Maguejo-Smolin framework thresholds may be raised or lowered. |
0710.1229 | Stefan Hild | S. Hild, M. Brinkmann, K. Danzmann, H. Grote, M. Hewitson, J. Hough,
H. Lueck, I. Martin, K. Mossavi, N. Rainer, S. Reid, J.R. Smith, K. Strain,
M. Weinert, P. Willems, B. Willke, W. Winkler | Photon pressure induced test mass deformation in gravitational-wave
detectors | null | Class.Quant.Grav.24:5681-5688,2007 | 10.1088/0264-9381/24/22/025 | null | gr-qc | null | A widely used assumption within the gravitational-wave community has so far
been that a test mass acts like a rigid body for frequencies in the detection
band, i.e. for frequencies far below the first internal resonance. In this
article we demonstrate that localized forces, applied for example by a photon
pressure actuator, can result in a non-negligible elastic deformation of the
test masses. For a photon pressure actuator setup used in the gravitational
wave detector GEO600 we measured that this effect modifies the standard
response function by 10% at 1 kHz and about 100% at 2.5 kHz.
| [
{
"created": "Fri, 5 Oct 2007 13:57:04 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Hild",
"S.",
""
],
[
"Brinkmann",
"M.",
""
],
[
"Danzmann",
"K.",
""
],
[
"Grote",
"H.",
""
],
[
"Hewitson",
"M.",
""
],
[
"Hough",
"J.",
""
],
[
"Lueck",
"H.",
""
],
[
"Martin",
"I.",
""
... | A widely used assumption within the gravitational-wave community has so far been that a test mass acts like a rigid body for frequencies in the detection band, i.e. for frequencies far below the first internal resonance. In this article we demonstrate that localized forces, applied for example by a photon pressure actuator, can result in a non-negligible elastic deformation of the test masses. For a photon pressure actuator setup used in the gravitational wave detector GEO600 we measured that this effect modifies the standard response function by 10% at 1 kHz and about 100% at 2.5 kHz. |
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