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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1005.3666
|
Paulo Vargas Moniz
|
Carlos Marques Afonso, Alfredo Barbosa Henriques, Paulo Vargas Moniz
|
A note on testing pre-inflationary times with gravitational-waves
|
10 pages, 2 figures
| null | null | null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A simple inflationary model based on loop quantum cosmology is considered.
Within this framework, we show that inflation does not necessarily erase the
infor- mation prior to its onset, but that such information may leave its
imprint in the energy-spectrum of the gravitational-waves generated at these
earliest of times.
|
[
{
"created": "Thu, 20 May 2010 11:35:25 GMT",
"version": "v1"
}
] |
2010-05-21
|
[
[
"Afonso",
"Carlos Marques",
""
],
[
"Henriques",
"Alfredo Barbosa",
""
],
[
"Moniz",
"Paulo Vargas",
""
]
] |
A simple inflationary model based on loop quantum cosmology is considered. Within this framework, we show that inflation does not necessarily erase the infor- mation prior to its onset, but that such information may leave its imprint in the energy-spectrum of the gravitational-waves generated at these earliest of times.
|
1904.01060
|
Nelson V Nunes
|
N. V. Nunes (1), N. Bartel (1), M. F. Bietenholz (1 and 2), M. V.
Zakhvatkin (3), D. A. Litvinov (4, 5 and 6), V. N. Rudenko (4), L. I. Gurvits
(7 and 8), G. Granato (8), D. Dirkx (8) ((1) York University, (2) South
African Radio Astronomy Observatory, (3) Keldysh Institute for Applied
Mathematics, (4) Sternberg Astronomical Institute, (5) Astro Space Center,
(6) Bauman Moscow State Technical University, (7) Joint Institute for VLBI
ERIC, (8) Delft University of Technology)
|
The gravitational redshift monitored with RadioAstron from near Earth up
to 350,000 km
|
16 pages, 6 figures, accepted for publication in Advances in Space
Research. arXiv admin note: text overlap with arXiv:1710.10074
| null |
10.1016/j.asr.2019.03.012
| null |
gr-qc astro-ph.IM
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We report on our efforts to test the Einstein Equivalence Principle by
measuring the gravitational redshift with the VLBI spacecraft RadioAstron, in
an eccentric orbit around Earth with geocentric distances as small as $\sim$
7,000 km and up to 350,000 km. The spacecraft and its ground stations are each
equipped with stable hydrogen maser frequency standards, and measurements of
the redshifted downlink carrier frequencies were obtained at both 8.4 and 15
GHz between 2012 and 2017. Over the course of the $\sim$ 9 d orbit, the
gravitational redshift between the spacecraft and the ground stations varies
between $6.8 \times 10^{-10}$ and $0.6 \times 10^{-10}$. Since the clock offset
between the masers is difficult to estimate independently of the gravitational
redshift, only the variation of the gravitational redshift is considered for
this analysis. We obtain a preliminary estimate of the fractional deviation of
the gravitational redshift from prediction of $\epsilon = -0.016 \pm 0.003_{\rm
stat} \pm 0.030_{\rm syst}$ with the systematic uncertainty likely being
dominated by unmodelled effects including the error in accounting for the
non-relativistic Doppler shift. This result is consistent with zero within the
uncertainties. For the first time, the gravitational redshift has been probed
over such large distances in the vicinity of Earth. About three orders of
magnitude more accurate estimates may be possible with RadioAstron using
existing data from dedicated interleaved observations combining uplink and
downlink modes of operation.
|
[
{
"created": "Mon, 1 Apr 2019 18:35:28 GMT",
"version": "v1"
}
] |
2019-04-03
|
[
[
"Nunes",
"N. V.",
"",
"1 and 2"
],
[
"Bartel",
"N.",
"",
"1 and 2"
],
[
"Bietenholz",
"M. F.",
"",
"1 and 2"
],
[
"Zakhvatkin",
"M. V.",
"",
"4, 5 and 6"
],
[
"Litvinov",
"D. A.",
"",
"4, 5 and 6"
],
[
"Rudenko",
"V. N.",
"",
"7 and 8"
],
[
"Gurvits",
"L. I.",
"",
"7 and 8"
],
[
"Granato",
"G.",
""
],
[
"Dirkx",
"D.",
""
]
] |
We report on our efforts to test the Einstein Equivalence Principle by measuring the gravitational redshift with the VLBI spacecraft RadioAstron, in an eccentric orbit around Earth with geocentric distances as small as $\sim$ 7,000 km and up to 350,000 km. The spacecraft and its ground stations are each equipped with stable hydrogen maser frequency standards, and measurements of the redshifted downlink carrier frequencies were obtained at both 8.4 and 15 GHz between 2012 and 2017. Over the course of the $\sim$ 9 d orbit, the gravitational redshift between the spacecraft and the ground stations varies between $6.8 \times 10^{-10}$ and $0.6 \times 10^{-10}$. Since the clock offset between the masers is difficult to estimate independently of the gravitational redshift, only the variation of the gravitational redshift is considered for this analysis. We obtain a preliminary estimate of the fractional deviation of the gravitational redshift from prediction of $\epsilon = -0.016 \pm 0.003_{\rm stat} \pm 0.030_{\rm syst}$ with the systematic uncertainty likely being dominated by unmodelled effects including the error in accounting for the non-relativistic Doppler shift. This result is consistent with zero within the uncertainties. For the first time, the gravitational redshift has been probed over such large distances in the vicinity of Earth. About three orders of magnitude more accurate estimates may be possible with RadioAstron using existing data from dedicated interleaved observations combining uplink and downlink modes of operation.
|
gr-qc/9606064
|
Jose Ademir Sales de Lima
|
L. R. W. Abramo (Brown University, Providence, RI, USA) and J. A. S.
Lima (Brown University, Providence, RI, USA and Universidade Federal do Rio
grande do Norte, Natal, RN, Brazil)
|
Inflationary Models Driven by Adiabatic Matter Creation
|
25 pages, 2 figures(available from the authors), uses LATEX
|
Class.Quant.Grav. 13 (1996) 2953-2964
|
10.1088/0264-9381/13/11/011
|
Brown-HET-1009
|
gr-qc
| null |
The flat inflationary dust universe with matter creation proposed by
Prigogine and coworkers is generalized and its dynamical properties are
reexamined. It is shown that the starting point of these models depends
critically on a dimensionless parameter $\Sigma$, closely related to the matter
creation rate $\psi$. For $\Sigma$ bigger or smaller than unity flat universes
can emerge, respectively, either like a Big-Bang FRW singularity or as a
Minkowski space-time at $t=-\infty$. The case $\Sigma=1$ corresponds to a de
Sitter-type solution, a fixed point in the phase diagram of the system,
supported by the matter creation process. The curvature effects have also been
investigated. The inflating de Sitter is a universal attractor for all
expanding solutions regardless of the initial conditions as well as of the
curvature parameter.
|
[
{
"created": "Fri, 21 Jun 1996 04:18:17 GMT",
"version": "v1"
}
] |
2009-10-28
|
[
[
"Abramo",
"L. R. W.",
"",
"Brown University, Providence, RI, USA"
],
[
"Lima",
"J. A. S.",
"",
"Brown University, Providence, RI, USA and Universidade Federal do Rio\n grande do Norte, Natal, RN, Brazil"
]
] |
The flat inflationary dust universe with matter creation proposed by Prigogine and coworkers is generalized and its dynamical properties are reexamined. It is shown that the starting point of these models depends critically on a dimensionless parameter $\Sigma$, closely related to the matter creation rate $\psi$. For $\Sigma$ bigger or smaller than unity flat universes can emerge, respectively, either like a Big-Bang FRW singularity or as a Minkowski space-time at $t=-\infty$. The case $\Sigma=1$ corresponds to a de Sitter-type solution, a fixed point in the phase diagram of the system, supported by the matter creation process. The curvature effects have also been investigated. The inflating de Sitter is a universal attractor for all expanding solutions regardless of the initial conditions as well as of the curvature parameter.
|
2312.06692
|
Qingdi Wang
|
Qingdi Wang
|
Extra Attraction Generated by Spacetime Fluctuations
|
29 pages
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We show that, due to the nonlinear nature of gravity, fluctuations in
spacetime curvature generate additional gravitational attraction. This
fluctuation-induced extra attraction was overlooked in the conventional
understanding of the cosmological constant problem. If the quantum vacuum of
matter fields possesses positive energy and negative pressure, it would produce
enormous gravitational repulsion, resulting in a catastrophic explosion of the
universe -- the acceleration of the universe's expansion would exceed the
observed value by some 120 orders of magnitude. We argue that such an enormous
repulsion produced by the violent matter fields vacuum can be completely
suppressed by the even more substantial attraction generated by the zero-point
fluctuations in the spacetime curvature. As a result, the predicted
catastrophic explosion of the universe is averted. Furthermore, at small
microscopic scales, the structure of spacetime becomes locally highly
inhomogeneous and anisotropic. When averaged over large macroscopic scales, the
zero-point fluctuations of spacetime itself could drive the observed slow
acceleration of the universe's expansion through a subtle parametric resonance
effect.
|
[
{
"created": "Sat, 9 Dec 2023 15:13:06 GMT",
"version": "v1"
},
{
"created": "Mon, 1 Jan 2024 10:20:10 GMT",
"version": "v2"
},
{
"created": "Mon, 8 Jan 2024 18:13:23 GMT",
"version": "v3"
}
] |
2024-01-09
|
[
[
"Wang",
"Qingdi",
""
]
] |
We show that, due to the nonlinear nature of gravity, fluctuations in spacetime curvature generate additional gravitational attraction. This fluctuation-induced extra attraction was overlooked in the conventional understanding of the cosmological constant problem. If the quantum vacuum of matter fields possesses positive energy and negative pressure, it would produce enormous gravitational repulsion, resulting in a catastrophic explosion of the universe -- the acceleration of the universe's expansion would exceed the observed value by some 120 orders of magnitude. We argue that such an enormous repulsion produced by the violent matter fields vacuum can be completely suppressed by the even more substantial attraction generated by the zero-point fluctuations in the spacetime curvature. As a result, the predicted catastrophic explosion of the universe is averted. Furthermore, at small microscopic scales, the structure of spacetime becomes locally highly inhomogeneous and anisotropic. When averaged over large macroscopic scales, the zero-point fluctuations of spacetime itself could drive the observed slow acceleration of the universe's expansion through a subtle parametric resonance effect.
|
1612.08744
|
Alan Kostelecky
|
Joshua Foster, Alan Kostelecky, Rui Xu
|
Constraints on Nonmetricity from Bounds on Lorentz Violation
|
13 pages
|
Phys. Rev. D 95, 084033 (2017)
|
10.1103/PhysRevD.95.084033
|
IUHET 623, December 2016
|
gr-qc hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Spacetime nonmetricity can be studied experimentally through its couplings to
fermions and photons. We use recent high-precision searches for Lorentz
violation to deduce first constraints involving the 40 independent nonmetricity
components down to levels of order $10^{-43}$ GeV.
|
[
{
"created": "Tue, 27 Dec 2016 21:00:00 GMT",
"version": "v1"
}
] |
2017-04-24
|
[
[
"Foster",
"Joshua",
""
],
[
"Kostelecky",
"Alan",
""
],
[
"Xu",
"Rui",
""
]
] |
Spacetime nonmetricity can be studied experimentally through its couplings to fermions and photons. We use recent high-precision searches for Lorentz violation to deduce first constraints involving the 40 independent nonmetricity components down to levels of order $10^{-43}$ GeV.
|
gr-qc/0003041
|
Maria Emilia
|
S. R. M. Masalskiene (Depto. de Matematica, UnB) and M. E. X.
Guimaraes (Depto. de Matematica, UnB)
|
Cosmic String Wakes in Scalar-Tensor Gravities
|
Replaced version to be published in the Classical and Quantum Gravity
|
Class.Quant.Grav. 17 (2000) 3055
|
10.1088/0264-9381/17/15/313
| null |
gr-qc astro-ph
| null |
The formation and evolution of cosmic string wakes in the framework of a
scalar-tensor gravity are investigated in this work. We consider a simple model
in which cold dark matter flows past an ordinary string and we treat this
motion in the Zel'dovich approximation. We make a comaprison between our
results and previous results obtained in the context of General Relativity. We
propose a mechanism in which the contribution of the scalar field to the
evolution of the wakes may lead to a cosmological observation.
|
[
{
"created": "Thu, 9 Mar 2000 17:29:51 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Jun 2000 17:03:50 GMT",
"version": "v2"
}
] |
2009-10-31
|
[
[
"Masalskiene",
"S. R. M.",
"",
"Depto. de Matematica, UnB"
],
[
"Guimaraes",
"M. E. X.",
"",
"Depto. de Matematica, UnB"
]
] |
The formation and evolution of cosmic string wakes in the framework of a scalar-tensor gravity are investigated in this work. We consider a simple model in which cold dark matter flows past an ordinary string and we treat this motion in the Zel'dovich approximation. We make a comaprison between our results and previous results obtained in the context of General Relativity. We propose a mechanism in which the contribution of the scalar field to the evolution of the wakes may lead to a cosmological observation.
|
gr-qc/0703131
|
Didier Solis
|
Gregory J. Galloway and Didier A. Solis
|
Uniqueness of de Sitter space
|
22 pages, 2 figures
|
Class.Quant.Grav.24:3125-3138,2007
|
10.1088/0264-9381/24/11/021
| null |
gr-qc hep-th math.DG
| null |
All inextendible null geodesics in four dimensional de Sitter space dS^4 are
complete and globally achronal. This achronality is related to the fact that
all observer horizons in dS^4 are eternal, i.e. extend from future infinity
scri^+ all the way back to past infinity scri^-. We show that the property of
having a null line (inextendible achronal null geodesic) that extends from
scri^- to scri^+ characterizes dS^4 among all globally hyperbolic and
asymptotically de Sitter spacetimes satisfying the vacuum Einstein equations
with positive cosmological constant. This result is then further extended to
allow for a class of matter models that includes perfect fluids.
|
[
{
"created": "Tue, 27 Mar 2007 17:53:15 GMT",
"version": "v1"
}
] |
2008-11-26
|
[
[
"Galloway",
"Gregory J.",
""
],
[
"Solis",
"Didier A.",
""
]
] |
All inextendible null geodesics in four dimensional de Sitter space dS^4 are complete and globally achronal. This achronality is related to the fact that all observer horizons in dS^4 are eternal, i.e. extend from future infinity scri^+ all the way back to past infinity scri^-. We show that the property of having a null line (inextendible achronal null geodesic) that extends from scri^- to scri^+ characterizes dS^4 among all globally hyperbolic and asymptotically de Sitter spacetimes satisfying the vacuum Einstein equations with positive cosmological constant. This result is then further extended to allow for a class of matter models that includes perfect fluids.
|
gr-qc/9803012
|
Friedrich W. Hehl
|
A. Garcia, F.W. Hehl, C. Laemmerzahl, A. Macias, J. Soccorro
|
Pleba\'nski-Demia\'nski-like solutions in metric-affine gravity
|
12 pages of a LaTeX-file
|
Class.Quant.Grav. 15 (1998) 1793-1799
|
10.1088/0264-9381/15/6/025
|
Cologne-ThP-He1-Nov97
|
gr-qc
| null |
We consider a (non--Riemannian) metric--affine gravity theory, in particular
its nonmetricity--torsion sector ``isomorphic'' to the Einstein--Maxwell
theory. We map certain Einstein--Maxwell electrovacuum solutions to it, namely
the Pleba\'nski--Demia\'nski class of Petrov type D metrics.
|
[
{
"created": "Tue, 3 Mar 1998 20:57:29 GMT",
"version": "v1"
}
] |
2009-10-31
|
[
[
"Garcia",
"A.",
""
],
[
"Hehl",
"F. W.",
""
],
[
"Laemmerzahl",
"C.",
""
],
[
"Macias",
"A.",
""
],
[
"Soccorro",
"J.",
""
]
] |
We consider a (non--Riemannian) metric--affine gravity theory, in particular its nonmetricity--torsion sector ``isomorphic'' to the Einstein--Maxwell theory. We map certain Einstein--Maxwell electrovacuum solutions to it, namely the Pleba\'nski--Demia\'nski class of Petrov type D metrics.
|
2301.00684
|
Vladimir Karas
|
Vladimir Karas
|
Astrophysical black holes embedded in organized magnetic fields: Case of
a nonvanishing electric charge
|
7 pages, 1 figure, in the Proceedings of RAGtime Conference, eds. Z.
Stuchlik et al. (2023, Opava, Czech Republic), ISBN 978-80-7510-576-9
(Print), ISBN 978-80-7510-577-6 (Online), pp. 13-19
| null | null | null |
gr-qc astro-ph.HE
|
http://creativecommons.org/licenses/by/4.0/
|
Large scale magnetic fields pervade the cosmic environment where the
astrophysical black holes are often embedded and influenced by the mutual
interaction. In this contribution we outline the appropriate mathematical
framework to describe magnetized black holes within General Relativity and we
show several examples how these can be employed in the astrophysical context.
In particular, we examine the magnetized black hole metric in terms of an exact
solution of electro-vacuum Einstein-Maxwell equations under the influence of a
non-vanishing electric charge. New effects emerge: the expulsion of the
magnetic flux out of the black-hole horizon depends on the intensity of the
imposed magnetic field.
|
[
{
"created": "Tue, 27 Dec 2022 13:55:21 GMT",
"version": "v1"
},
{
"created": "Fri, 29 Dec 2023 20:52:47 GMT",
"version": "v2"
}
] |
2024-01-02
|
[
[
"Karas",
"Vladimir",
""
]
] |
Large scale magnetic fields pervade the cosmic environment where the astrophysical black holes are often embedded and influenced by the mutual interaction. In this contribution we outline the appropriate mathematical framework to describe magnetized black holes within General Relativity and we show several examples how these can be employed in the astrophysical context. In particular, we examine the magnetized black hole metric in terms of an exact solution of electro-vacuum Einstein-Maxwell equations under the influence of a non-vanishing electric charge. New effects emerge: the expulsion of the magnetic flux out of the black-hole horizon depends on the intensity of the imposed magnetic field.
|
gr-qc/9805093
|
Trinidad Ramirez Trejo
|
B. Mashhoon, J.C. McClune, and H. Quevedo
|
The gravitoelectromagnetic stress-energy tensor
|
16 pages, Latex, 1 figure (not included)
|
Class.Quant.Grav. 16 (1999) 1137-1148
|
10.1088/0264-9381/16/4/004
| null |
gr-qc
| null |
We study the pseudo-local gravitoelectromagnetic stress-energy tensor for an
arbitrary gravitational field within the framework of general relativity. It is
shown that there exists a current of gravitational energy around a rotating
mass. This gravitational analog of the Poynting flux is evaluated for certain
classes of observers in the Kerr field.
|
[
{
"created": "Wed, 27 May 1998 00:45:50 GMT",
"version": "v1"
}
] |
2009-10-31
|
[
[
"Mashhoon",
"B.",
""
],
[
"McClune",
"J. C.",
""
],
[
"Quevedo",
"H.",
""
]
] |
We study the pseudo-local gravitoelectromagnetic stress-energy tensor for an arbitrary gravitational field within the framework of general relativity. It is shown that there exists a current of gravitational energy around a rotating mass. This gravitational analog of the Poynting flux is evaluated for certain classes of observers in the Kerr field.
|
2107.04862
|
Jen-Tsung Hsiang
|
Jen-Tsung Hsiang and Bei-Lok Hu
|
Dynamical Response of an Unruh-DeWitt Detector in a Quantum Field over
the History of the Universe
|
36 pages, 1 figure. v2: This paper is published in Ann. Phys. (NY)
doi.org/10.1016/j.aop.2021.168656 under the title "NonMarkovianity in
cosmology: Memories kept in a quantum field"
|
Ann. Phys. 434, 168656 (2021)
|
10.1016/j.aop.2021.168656
| null |
gr-qc hep-th quant-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this work we ask how an Unruh-DeWitt (UD) detector with harmonic
oscillator internal degrees of freedom $Q$ measuring an evolving quantum matter
field $\Phi(\bm{x}, t)$ in an expanding universe with scale factor $a(t)$
responds. We investigate the detector's response which contains non-Markovian
information about the quantum field squeezed by the dynamical spacetime. The
challenge is in the memory effects accumulated over the evolutionary history.
We first consider a detector $W$, the `\textsl{Witness}', which co-existed and
evolved with the quantum field from the beginning. We derive a nonMarkovian
quantum Langevin equation for the detector's $Q$ by integrating over the
squeezed quantum field. The solution of this integro-differential equation
would answer our question, in principle, but very challenging, in practice.
Striking a compromise, we then ask, to what extent can a detector $D$
introduced at late times, called the `\textsl{Detective}', decipher past
memories. This situation corresponds to many cosmological experiments today
probing specific stages in the past, such as COBE targeting activities at the
surface of last scattering. Somewhat surprisingly we show that it is possible
to retrieve to some degree certain global physical quantities, such as the
resultant squeezing, particles created, quantum coherence and correlations. The
reason is because the quantum field has all the fine-grained information from
the beginning in how it was driven by the cosmic dynamics $a(t)$. How long the
details of past history can persist in the quantum field depends on the memory
time. The fact that a squeezed field cannot come to complete equilibrium under
constant driving, as in an evolving spacetime, actually helps to retain the
memory. We discuss interesting features and potentials of this
`\textit{archaeological}' perspective toward cosmological issues.
|
[
{
"created": "Sat, 10 Jul 2021 15:36:53 GMT",
"version": "v1"
},
{
"created": "Tue, 4 Jan 2022 03:32:44 GMT",
"version": "v2"
}
] |
2022-01-11
|
[
[
"Hsiang",
"Jen-Tsung",
""
],
[
"Hu",
"Bei-Lok",
""
]
] |
In this work we ask how an Unruh-DeWitt (UD) detector with harmonic oscillator internal degrees of freedom $Q$ measuring an evolving quantum matter field $\Phi(\bm{x}, t)$ in an expanding universe with scale factor $a(t)$ responds. We investigate the detector's response which contains non-Markovian information about the quantum field squeezed by the dynamical spacetime. The challenge is in the memory effects accumulated over the evolutionary history. We first consider a detector $W$, the `\textsl{Witness}', which co-existed and evolved with the quantum field from the beginning. We derive a nonMarkovian quantum Langevin equation for the detector's $Q$ by integrating over the squeezed quantum field. The solution of this integro-differential equation would answer our question, in principle, but very challenging, in practice. Striking a compromise, we then ask, to what extent can a detector $D$ introduced at late times, called the `\textsl{Detective}', decipher past memories. This situation corresponds to many cosmological experiments today probing specific stages in the past, such as COBE targeting activities at the surface of last scattering. Somewhat surprisingly we show that it is possible to retrieve to some degree certain global physical quantities, such as the resultant squeezing, particles created, quantum coherence and correlations. The reason is because the quantum field has all the fine-grained information from the beginning in how it was driven by the cosmic dynamics $a(t)$. How long the details of past history can persist in the quantum field depends on the memory time. The fact that a squeezed field cannot come to complete equilibrium under constant driving, as in an evolving spacetime, actually helps to retain the memory. We discuss interesting features and potentials of this `\textit{archaeological}' perspective toward cosmological issues.
|
0711.4188
|
Subenoy Chakraborty
|
Asit Banerjee, Tanwi Bandyopadhyay and Subenoy Chakraborty
|
Emergent Universe in Brane World Scenario with Schwarzschild-de Sitter
Bulk
|
4 pages, no figure, accepted for publication in Gen.Relt.Grav
|
Gen.Rel.Grav.40:1603-1607,2008
|
10.1007/s10714-007-0567-3
| null |
gr-qc
| null |
A model of an emergent universe is obtained in brane world. Here the bulk
energy is in the form of cosmological constant, while the brane consists of a
fluid satisfying an equation of state of the form $p_{b}={1/3} \rho_{b}$, which
is effectively a radiation equation of state at high energies. It is shown that
with the positive bulk cosmological constant, one of our models represents an
emergent universe.
|
[
{
"created": "Tue, 27 Nov 2007 06:51:13 GMT",
"version": "v1"
}
] |
2008-11-26
|
[
[
"Banerjee",
"Asit",
""
],
[
"Bandyopadhyay",
"Tanwi",
""
],
[
"Chakraborty",
"Subenoy",
""
]
] |
A model of an emergent universe is obtained in brane world. Here the bulk energy is in the form of cosmological constant, while the brane consists of a fluid satisfying an equation of state of the form $p_{b}={1/3} \rho_{b}$, which is effectively a radiation equation of state at high energies. It is shown that with the positive bulk cosmological constant, one of our models represents an emergent universe.
|
gr-qc/0307106
|
Dario Grasso
|
Dario Grasso
|
Graviton Production by a Thermal Bath
|
5 pages. To appear on the proceedings of the 28th International
Cosmic Rays Conference
| null | null | null |
gr-qc
| null |
Thermal fluctuations in the early universe plasma and in very hot
astrophysical objects are an unavoidable source of gravitational waves (GW).
Differently from previous studies on the subject, we approach this problem
using methods based on field theory at finite temperature. Such an approach
allows to probe the infrared region of the spectrum where dissipative effects
are dominant. Incidentally, this region is the most interesting from the point
of view of the detectability perspectives. We find significant deviations from
a Planck spectrum.
|
[
{
"created": "Thu, 24 Jul 2003 09:50:02 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Grasso",
"Dario",
""
]
] |
Thermal fluctuations in the early universe plasma and in very hot astrophysical objects are an unavoidable source of gravitational waves (GW). Differently from previous studies on the subject, we approach this problem using methods based on field theory at finite temperature. Such an approach allows to probe the infrared region of the spectrum where dissipative effects are dominant. Incidentally, this region is the most interesting from the point of view of the detectability perspectives. We find significant deviations from a Planck spectrum.
|
2104.10290
|
Florian Beyer
|
Florian Beyer and Joshua Ritchie
|
Asymptotically hyperboloidal initial data sets from a
parabolic-hyperbolic formulation of the Einstein vacuum constraints
|
Only minor changes. Matches the published version
|
2022 Class. Quantum Grav. 39 145012
|
10.1088/1361-6382/ac79f1
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, we continue our investigations of R\'acz's
parabolic-hyperbolic formulation of the Einstein vacuum constraints. Our
previous studies of the asymptotically flat setting provided strong evidence
for unstable asymptotics which we were able to resolve by introducing a certain
modification of R\'acz's parabolic-hyperbolic formulation. The primary focus of
the present paper here is the asymptotically hyperboloidal setting. We provide
evidence through a mixture of numerical and analytical methods that the
asymptotics of the solutions of R\'acz's parabolic-hyperbolic formulation is
stable, and, in particular, no modifications are necessary to obtain solutions
that are asymptotically hyperboloidal.
|
[
{
"created": "Wed, 21 Apr 2021 00:30:57 GMT",
"version": "v1"
},
{
"created": "Wed, 13 Jul 2022 01:40:58 GMT",
"version": "v2"
}
] |
2022-07-14
|
[
[
"Beyer",
"Florian",
""
],
[
"Ritchie",
"Joshua",
""
]
] |
In this paper, we continue our investigations of R\'acz's parabolic-hyperbolic formulation of the Einstein vacuum constraints. Our previous studies of the asymptotically flat setting provided strong evidence for unstable asymptotics which we were able to resolve by introducing a certain modification of R\'acz's parabolic-hyperbolic formulation. The primary focus of the present paper here is the asymptotically hyperboloidal setting. We provide evidence through a mixture of numerical and analytical methods that the asymptotics of the solutions of R\'acz's parabolic-hyperbolic formulation is stable, and, in particular, no modifications are necessary to obtain solutions that are asymptotically hyperboloidal.
|
1303.4070
|
Ian Hawke
|
I. Hawke, G. L. Comer, N. Andersson
|
The nonlinear development of the relativistic two-stream instability
|
15 pages, 9 figures
| null |
10.1088/0264-9381/30/14/145007
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The two-stream instability has been mooted as an explanation for a range of
astrophysical applications from GRBs and pulsar glitches to cosmology. Using
the first nonlinear numerical simulations of relativistic multi-species
hydrodynamics we show that the onset and initial growth of the instability is
very well described by linear perturbation theory. In the later stages the
linear and nonlinear description match only qualitatively, and the instability
does not saturate even in the nonlinear case by purely ideal hydrodynamic
effects.
|
[
{
"created": "Sun, 17 Mar 2013 15:30:51 GMT",
"version": "v1"
}
] |
2015-06-15
|
[
[
"Hawke",
"I.",
""
],
[
"Comer",
"G. L.",
""
],
[
"Andersson",
"N.",
""
]
] |
The two-stream instability has been mooted as an explanation for a range of astrophysical applications from GRBs and pulsar glitches to cosmology. Using the first nonlinear numerical simulations of relativistic multi-species hydrodynamics we show that the onset and initial growth of the instability is very well described by linear perturbation theory. In the later stages the linear and nonlinear description match only qualitatively, and the instability does not saturate even in the nonlinear case by purely ideal hydrodynamic effects.
|
gr-qc/0610067
|
Rafael Ferraro
|
Rafael Ferraro, Franco Fiorini
|
Modified teleparallel gravity: inflation without inflaton
|
4 pages, 2 figures. Version to be published in Physical Review D
|
Phys.Rev.D75:084031,2007
|
10.1103/PhysRevD.75.084031
| null |
gr-qc astro-ph hep-th
| null |
Born-Infeld strategy to smooth theories having divergent solutions is applied
to teleparallel equivalent of General Relativity. Differing from other theories
of modified gravity, modified teleparallelism leads to second order equations,
since teleparallel Lagrangian only contains first derivatives of the vierbein.
We show that Born-Infeld-modified teleparallelism solves the particle horizon
problem in a spatially flat FRW universe by providing an initial exponential
expansion without resorting to an inflaton field.
|
[
{
"created": "Thu, 12 Oct 2006 20:27:38 GMT",
"version": "v1"
},
{
"created": "Thu, 29 Mar 2007 17:14:29 GMT",
"version": "v2"
}
] |
2008-11-26
|
[
[
"Ferraro",
"Rafael",
""
],
[
"Fiorini",
"Franco",
""
]
] |
Born-Infeld strategy to smooth theories having divergent solutions is applied to teleparallel equivalent of General Relativity. Differing from other theories of modified gravity, modified teleparallelism leads to second order equations, since teleparallel Lagrangian only contains first derivatives of the vierbein. We show that Born-Infeld-modified teleparallelism solves the particle horizon problem in a spatially flat FRW universe by providing an initial exponential expansion without resorting to an inflaton field.
|
1406.6194
|
Eric Larsson
|
Eric Larsson
|
Smoothness of compact horizons
|
This is chapter one of arXiv:1406.6194v1, rewritten and improved
|
Ann. Henri Poincar\'e 16 (2015), no. 9, 2163-2214
|
10.1007/s00023-014-0371-z
| null |
gr-qc math.DG
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We prove that compact Cauchy horizons in a smooth spacetime satisfying the
null energy condition are smooth. As an application, we consider the problem of
determining when a cobordism admits Lorentzian metrics with certain properties.
In particular, we prove a result originally due to Tipler without the
smoothness hypothesis necessary in the original proof.
|
[
{
"created": "Tue, 24 Jun 2014 10:32:02 GMT",
"version": "v1"
},
{
"created": "Tue, 24 Jan 2017 13:40:29 GMT",
"version": "v2"
}
] |
2017-01-25
|
[
[
"Larsson",
"Eric",
""
]
] |
We prove that compact Cauchy horizons in a smooth spacetime satisfying the null energy condition are smooth. As an application, we consider the problem of determining when a cobordism admits Lorentzian metrics with certain properties. In particular, we prove a result originally due to Tipler without the smoothness hypothesis necessary in the original proof.
|
1807.03687
|
Ludovic Ducobu
|
Y.Brihaye, L.Ducobu
|
Spinning-Charged-Hairy Black Holes in 5-d Einstein gravity
|
12 pages, 5 figures. Results extended. References added
|
Phys. Rev. D 98, 064034 (2018)
|
10.1103/PhysRevD.98.064034
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The spinning-hairy black holes that occur in Einstein gravity supplemented by
a doublet of complex scalar fields are constructed within an extension of the
model by a $U(1)$ gauge symmetry involving a massless vector potential. The
hairy black holes then acquire an electric charge and a magnetic moment; their
domain of existence is discussed in terms of the gauge coupling constant.
|
[
{
"created": "Tue, 10 Jul 2018 14:50:10 GMT",
"version": "v1"
},
{
"created": "Thu, 26 Jul 2018 12:56:02 GMT",
"version": "v2"
}
] |
2018-12-19
|
[
[
"Brihaye",
"Y.",
""
],
[
"Ducobu",
"L.",
""
]
] |
The spinning-hairy black holes that occur in Einstein gravity supplemented by a doublet of complex scalar fields are constructed within an extension of the model by a $U(1)$ gauge symmetry involving a massless vector potential. The hairy black holes then acquire an electric charge and a magnetic moment; their domain of existence is discussed in terms of the gauge coupling constant.
|
1708.08849
|
Ion Vasile Vancea
|
Ion V. Vancea
|
On the existence of the field line solutions of the Einstein-Maxwell
equations
|
Misprints corrected. To be published in IJGMM
| null |
10.1142/S0219887818500548
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The main result of this paper is the proof that there are local electric and
magnetic field configurations expressed in terms of field lines on an arbitrary
hyperbolic manifold. This electromagnetic field is described by (dual)
solutions of the Maxwell's equations of the Einstein-Maxwell theory. These
solutions have the following important properties: i) they are general, in the
sense that the knot solutions are particular cases of them and ii) they reduce
to the electromagnetic fields in the field line representation in the flat
space-time. Also, we discuss briefly the real representation of these
electromagnetic configurations and write down the corresponding Einstein
equations.
|
[
{
"created": "Tue, 29 Aug 2017 16:04:29 GMT",
"version": "v1"
},
{
"created": "Wed, 30 Aug 2017 19:56:56 GMT",
"version": "v2"
},
{
"created": "Thu, 7 Sep 2017 11:04:28 GMT",
"version": "v3"
},
{
"created": "Mon, 4 Dec 2017 21:58:11 GMT",
"version": "v4"
}
] |
2017-12-06
|
[
[
"Vancea",
"Ion V.",
""
]
] |
The main result of this paper is the proof that there are local electric and magnetic field configurations expressed in terms of field lines on an arbitrary hyperbolic manifold. This electromagnetic field is described by (dual) solutions of the Maxwell's equations of the Einstein-Maxwell theory. These solutions have the following important properties: i) they are general, in the sense that the knot solutions are particular cases of them and ii) they reduce to the electromagnetic fields in the field line representation in the flat space-time. Also, we discuss briefly the real representation of these electromagnetic configurations and write down the corresponding Einstein equations.
|
gr-qc/0009056
|
Paulo Aguiar
|
Paulo Aguiar and Paulo Crawford
|
Dust-filled axially symmetric universes with a cosmological constant
|
12 pages, 9 figures, 1 table. Published in Physical Review D 15
|
Phys.Rev.D62:123511,2000
|
10.1103/PhysRevD.62.123511
| null |
gr-qc
| null |
Following the recent recognition of a positive value for the vacuum energy
density and the realization that a simple Kantowski-Sachs model might fit the
classical tests of cosmology, we study the qualitative behavior of three
anisotropic and homogeneous models: Kantowski-Sachs, Bianchi type-I and Bianchi
type-III universes, with dust and a cosmological constant, in order to find out
which are physically permitted. We find that these models undergo
isotropization up to the point that the observations will not be able to
distinguish between them and the standard model, except for the Kantowski-Sachs
model $(\Omega_{k_{0}}<0)$ and for the Bianchi type-III $(\Omega_{k_{0}}>0)$
with $\Omega_{\Lambda_{0}}$ smaller than some critical value
$\Omega_{\Lambda_{M}}$. Even if one imposes that the Universe should be nearly
isotropic since the last scattering epoch ($z\approx 1000$), meaning that the
Universe should have approximately the same Hubble parameter in all directions
(considering the COBE 4-Year data), there is still a large range for the matter
density parameter compatible with Kantowsky-Sachs and Bianchi type-III if
$|\Omega_0+\Omega_{\Lambda_0}-1|\leq \delta$, for a very small $\delta$ . The
Bianchi type-I model becomes exactly isotropic owing to our restrictions and we
have $\Omega_0+\Omega_{\Lambda_0}=1$ in this case. Of course, all these models
approach locally an exponential expanding state provided the cosmological
constant $\Omega_\Lambda>\Omega_{\Lambda_{M}}$.
|
[
{
"created": "Fri, 15 Sep 2000 16:06:14 GMT",
"version": "v1"
},
{
"created": "Fri, 19 Oct 2001 03:06:08 GMT",
"version": "v2"
}
] |
2008-11-26
|
[
[
"Aguiar",
"Paulo",
""
],
[
"Crawford",
"Paulo",
""
]
] |
Following the recent recognition of a positive value for the vacuum energy density and the realization that a simple Kantowski-Sachs model might fit the classical tests of cosmology, we study the qualitative behavior of three anisotropic and homogeneous models: Kantowski-Sachs, Bianchi type-I and Bianchi type-III universes, with dust and a cosmological constant, in order to find out which are physically permitted. We find that these models undergo isotropization up to the point that the observations will not be able to distinguish between them and the standard model, except for the Kantowski-Sachs model $(\Omega_{k_{0}}<0)$ and for the Bianchi type-III $(\Omega_{k_{0}}>0)$ with $\Omega_{\Lambda_{0}}$ smaller than some critical value $\Omega_{\Lambda_{M}}$. Even if one imposes that the Universe should be nearly isotropic since the last scattering epoch ($z\approx 1000$), meaning that the Universe should have approximately the same Hubble parameter in all directions (considering the COBE 4-Year data), there is still a large range for the matter density parameter compatible with Kantowsky-Sachs and Bianchi type-III if $|\Omega_0+\Omega_{\Lambda_0}-1|\leq \delta$, for a very small $\delta$ . The Bianchi type-I model becomes exactly isotropic owing to our restrictions and we have $\Omega_0+\Omega_{\Lambda_0}=1$ in this case. Of course, all these models approach locally an exponential expanding state provided the cosmological constant $\Omega_\Lambda>\Omega_{\Lambda_{M}}$.
|
1112.5812
|
Alexandre Baranov
|
Alexandre M.Baranov and Alexander Yu.Osipov
|
The Relativistic Fluid Ball as a Stratified Model of an Astrophysical
Object
|
3 pages, 2 figures, Talk given at the International Conference
RUDN-10, June 28-July 3, 2010, PFUR, Moscow
|
Gravitation & Cosmology, 2011, Vol.17, No.2, pp.173-175
|
10.1134/S020228931102006x
| null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A relativistic fluid ball with an inhomogeneous static stratified matter
configuration is considered. A model of an astrophysical object with this
structure of matter is constructed.
|
[
{
"created": "Mon, 26 Dec 2011 05:35:14 GMT",
"version": "v1"
}
] |
2011-12-30
|
[
[
"Baranov",
"Alexandre M.",
""
],
[
"Osipov",
"Alexander Yu.",
""
]
] |
A relativistic fluid ball with an inhomogeneous static stratified matter configuration is considered. A model of an astrophysical object with this structure of matter is constructed.
|
1911.03172
|
Andrei Erofeev
|
Andrei L. Erofeev
|
On dynamic aspects of the Proca field screening by a black hole
|
19 pages, 4 figures
| null |
10.1140/epjc/s10052-020-8044-1
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Classical black holes are known for almost half a century to nullify exterior
classical massive vector field associated with a charge crossing the event
horizon. This implies that, from the point of view of an external observer, the
Proca field of the charge is screened with the strength gradually increasing as
the charge adiabatically approaches the event horizon. In this paper we reject
the adiabaticity constraint and calculate analytically the field evolution with
respect to a distant observer in the frame of the simplest model of a
contracting charged spherical shell concentrically surrounding a Schwarzschild
black hole. We show that a time scale of the screening is determined by a mass
of the black hole and, moreover, loss of Proca hair during the collapse of
charged matter has the same temporal character. The latter conclusion disproves
results of a number of papers. Due to existence of the event horizon, there is
discontinuous jump between massive and massless electrodynamics. This means
that presence of an arbitrarily small mass of the photon gives rise to
experimentally observed effects including generation of electric asymmetry of
the Universe and galactic magnetic fields.
|
[
{
"created": "Fri, 8 Nov 2019 10:35:47 GMT",
"version": "v1"
},
{
"created": "Mon, 18 Nov 2019 10:54:04 GMT",
"version": "v2"
}
] |
2020-06-24
|
[
[
"Erofeev",
"Andrei L.",
""
]
] |
Classical black holes are known for almost half a century to nullify exterior classical massive vector field associated with a charge crossing the event horizon. This implies that, from the point of view of an external observer, the Proca field of the charge is screened with the strength gradually increasing as the charge adiabatically approaches the event horizon. In this paper we reject the adiabaticity constraint and calculate analytically the field evolution with respect to a distant observer in the frame of the simplest model of a contracting charged spherical shell concentrically surrounding a Schwarzschild black hole. We show that a time scale of the screening is determined by a mass of the black hole and, moreover, loss of Proca hair during the collapse of charged matter has the same temporal character. The latter conclusion disproves results of a number of papers. Due to existence of the event horizon, there is discontinuous jump between massive and massless electrodynamics. This means that presence of an arbitrarily small mass of the photon gives rise to experimentally observed effects including generation of electric asymmetry of the Universe and galactic magnetic fields.
|
1706.08010
|
Faramarz Rahmani
|
Faramarz Rahmani and Mehdi Golshani
|
Some clarifications about the Bohmian geodesic deviation equation and
Raychaudhuri's equation
| null | null |
10.1142/S0217751X18500276
| null |
gr-qc quant-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
One of the important and famous topics in general theory of relativity and
gravitation is the problem of geodesic deviation and its related singularity
theorems. An interesting subject is the investigation of these concepts when
quantum effects are considered. Since, the definition of trajectory is not
possible in the framework of standard quantum mechanics (SQM), we investigate
the problem of geodesic equation and its related topics in the framework of
Bohmian quantum mechanics in which the definition of trajectory is possible. We
do this in a fixed background and we do not consider the back-reaction effects
of matter on the spacetime metric.
|
[
{
"created": "Sat, 24 Jun 2017 22:48:50 GMT",
"version": "v1"
}
] |
2018-02-28
|
[
[
"Rahmani",
"Faramarz",
""
],
[
"Golshani",
"Mehdi",
""
]
] |
One of the important and famous topics in general theory of relativity and gravitation is the problem of geodesic deviation and its related singularity theorems. An interesting subject is the investigation of these concepts when quantum effects are considered. Since, the definition of trajectory is not possible in the framework of standard quantum mechanics (SQM), we investigate the problem of geodesic equation and its related topics in the framework of Bohmian quantum mechanics in which the definition of trajectory is possible. We do this in a fixed background and we do not consider the back-reaction effects of matter on the spacetime metric.
|
gr-qc/9607036
| null |
S. Demelio and S. Mignemi
|
Multi-black holes and instantons in effective string theory
|
10 pages, plain TeX
|
Int.J.Mod.Phys. D7 (1998) 73-80
|
10.1142/S0218271898000073
|
INFNCA-TH611
|
gr-qc
| null |
The effective action for string theory which takes into account non-minimal
coupling of moduli admits multi-black hole solutions. The euclidean
continuation of these solutions can be interpreted as an instanton mediating
the splitting and recombination of the throat of extremal magnetically charged
black holes.
|
[
{
"created": "Tue, 16 Jul 1996 19:23:35 GMT",
"version": "v1"
}
] |
2015-06-25
|
[
[
"Demelio",
"S.",
""
],
[
"Mignemi",
"S.",
""
]
] |
The effective action for string theory which takes into account non-minimal coupling of moduli admits multi-black hole solutions. The euclidean continuation of these solutions can be interpreted as an instanton mediating the splitting and recombination of the throat of extremal magnetically charged black holes.
|
1909.08915
|
Jo\~ao M. Oliveira
|
Carlos A. R. Herdeiro, Jo\~ao M. S. Oliveira
|
On the inexistence of self-gravitating solitons in generalised axion
electrodynamics
|
10 pages, no figures
| null |
10.1016/j.physletb.2019.135076
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Building upon the methods used recently, we establish the inexistence of
self-gravitating solitonic solutions for both static and strictly stationary
asymptotically flat spacetimes in generalised axion electrodynamics. This is an
Einstein-Maxwell-axion model, where the axion field $\theta$ is non-minimally
coupled to the electromagnetic field. Considering the standard QCD axion
coupling, we first present an argument for the absence of static axionic
solitons, $i.e.$ localised energy axionic-electromagnetic configurations,
yielding an everywhere regular, horizonless, asymptotically flat, static
spacetime. Then, for generic couplings $f(\theta)$ and $g(\theta)$ (subject to
mild assumptions) between the axion field and the electromagnetic field
invariants, we show there are still no solitonic solutions, even when dropping
the staticity assumption and merely requiring a strictly stationary spacetime,
regardless of the spatial isometries.
|
[
{
"created": "Thu, 19 Sep 2019 10:59:59 GMT",
"version": "v1"
}
] |
2020-01-08
|
[
[
"Herdeiro",
"Carlos A. R.",
""
],
[
"Oliveira",
"João M. S.",
""
]
] |
Building upon the methods used recently, we establish the inexistence of self-gravitating solitonic solutions for both static and strictly stationary asymptotically flat spacetimes in generalised axion electrodynamics. This is an Einstein-Maxwell-axion model, where the axion field $\theta$ is non-minimally coupled to the electromagnetic field. Considering the standard QCD axion coupling, we first present an argument for the absence of static axionic solitons, $i.e.$ localised energy axionic-electromagnetic configurations, yielding an everywhere regular, horizonless, asymptotically flat, static spacetime. Then, for generic couplings $f(\theta)$ and $g(\theta)$ (subject to mild assumptions) between the axion field and the electromagnetic field invariants, we show there are still no solitonic solutions, even when dropping the staticity assumption and merely requiring a strictly stationary spacetime, regardless of the spatial isometries.
|
gr-qc/0103097
|
Serge Massar
|
R. Brout
|
Who is the Inflaton?
|
extensively revised version presented at the Corfu School and
Workshop of Theoretical Physics 2001
| null | null |
ULB-TH/01-06
|
gr-qc
| null |
In the context of the two-fluid model introduced to tame the transplanckian
problem of black hole physics, the inflaton field of the chaotic inflation
scenario is identified with the fluctuation of the density of modes. Its mass
comes about from the exchange of degrees of freedom between the two fluids.
|
[
{
"created": "Tue, 27 Mar 2001 11:21:08 GMT",
"version": "v1"
},
{
"created": "Fri, 10 Aug 2001 10:42:22 GMT",
"version": "v2"
},
{
"created": "Mon, 17 Dec 2001 10:54:17 GMT",
"version": "v3"
}
] |
2007-05-23
|
[
[
"Brout",
"R.",
""
]
] |
In the context of the two-fluid model introduced to tame the transplanckian problem of black hole physics, the inflaton field of the chaotic inflation scenario is identified with the fluctuation of the density of modes. Its mass comes about from the exchange of degrees of freedom between the two fluids.
|
1608.00685
|
Miguel Campiglia
|
Miguel Campiglia, Alok Laddha
|
Sub-subleading soft gravitons and large diffeomorphisms
|
41 pages
| null |
10.1007/JHEP01(2017)036
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present strong evidence that the sub-subleading soft theorem in
semi-classical (tree level) gravity discovered by Cachazo and Strominger is
equivalent to the conservation of asymptotic charges associated to a new class
of vector fields not contained within the previous extensions of BMS algebra.
Our analysis crucially relies on analyzing the hitherto established
equivalences between soft theorems and Ward identities from a new perspective.
In this process we naturally (re)discover a class of `magnetic' charges at null
infinity that are associated to the dual of the Weyl tensor.
|
[
{
"created": "Tue, 2 Aug 2016 02:52:55 GMT",
"version": "v1"
}
] |
2017-02-01
|
[
[
"Campiglia",
"Miguel",
""
],
[
"Laddha",
"Alok",
""
]
] |
We present strong evidence that the sub-subleading soft theorem in semi-classical (tree level) gravity discovered by Cachazo and Strominger is equivalent to the conservation of asymptotic charges associated to a new class of vector fields not contained within the previous extensions of BMS algebra. Our analysis crucially relies on analyzing the hitherto established equivalences between soft theorems and Ward identities from a new perspective. In this process we naturally (re)discover a class of `magnetic' charges at null infinity that are associated to the dual of the Weyl tensor.
|
gr-qc/0411063
|
Kirill Bronnikov
|
K.A. Bronnikov, S.V. Grinyok
|
Conformal continuations and wormhole instability in scalar-tensor
gravity
|
8 two-column pages, latex, gc style
|
Grav.Cosmol. 10 (2004) 237
| null | null |
gr-qc
| null |
We study the stability of static, spherically symmetric, traversable
wormholes existing due to conformal continuations in a class of scalar-tensor
theories with zero scalar field potential (so that Fisher's well-known
scalar-vacuum solution holds in the Einstein conformal frame). Specific
examples of such wormholes are those with nonminimally (e.g., conformally)
coupled scalar fields. All boundary conditions for scalar and metric
perturbations are taken into account. All such wormholes are shown to be
unstable under spherically symmetric perturbations. The instability is proved
analytically with the aid of the theory of self-adjoint operators in Hilbert
space and is confirmed by a numerical computation.
|
[
{
"created": "Fri, 12 Nov 2004 14:23:44 GMT",
"version": "v1"
}
] |
2016-08-31
|
[
[
"Bronnikov",
"K. A.",
""
],
[
"Grinyok",
"S. V.",
""
]
] |
We study the stability of static, spherically symmetric, traversable wormholes existing due to conformal continuations in a class of scalar-tensor theories with zero scalar field potential (so that Fisher's well-known scalar-vacuum solution holds in the Einstein conformal frame). Specific examples of such wormholes are those with nonminimally (e.g., conformally) coupled scalar fields. All boundary conditions for scalar and metric perturbations are taken into account. All such wormholes are shown to be unstable under spherically symmetric perturbations. The instability is proved analytically with the aid of the theory of self-adjoint operators in Hilbert space and is confirmed by a numerical computation.
|
2307.12876
|
Frans Klinkhamer
|
F.R. Klinkhamer
|
Higher-dimensional extension of a vacuum-defect wormhole
|
11 pages, 2 figures, v3: appendix added on 4D interpolating metrics
| null | null |
KA-TP-15-2023
|
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present a 5D metric which interpolates between the standard 4D
Schwarzschild metric with mass parameter $M$ and a new 4D $M$-deformed
vacuum-defect-wormhole metric. The 5D spacetime can, in principle, have an
infinite mass density that gives rise to the $M$ parameter of the 4D
$M$-deformed vacuum-defect wormhole. For completeness, we also give 4D
interpolating metrics between the original vacuum-defect wormhole at the
wormhole throat and the $M$-deformed vacuum-defect wormhole at spatial
infinity.
|
[
{
"created": "Mon, 24 Jul 2023 15:16:44 GMT",
"version": "v1"
},
{
"created": "Thu, 27 Jul 2023 17:23:43 GMT",
"version": "v2"
},
{
"created": "Mon, 21 Aug 2023 14:40:26 GMT",
"version": "v3"
}
] |
2023-08-22
|
[
[
"Klinkhamer",
"F. R.",
""
]
] |
We present a 5D metric which interpolates between the standard 4D Schwarzschild metric with mass parameter $M$ and a new 4D $M$-deformed vacuum-defect-wormhole metric. The 5D spacetime can, in principle, have an infinite mass density that gives rise to the $M$ parameter of the 4D $M$-deformed vacuum-defect wormhole. For completeness, we also give 4D interpolating metrics between the original vacuum-defect wormhole at the wormhole throat and the $M$-deformed vacuum-defect wormhole at spatial infinity.
|
gr-qc/9506085
|
David Brown
|
David Brown
|
Black Hole Entropy and the Hamiltonian Formulation of Diffeomorphism
Invariant Theories
|
26 pages, REVTeX
|
Phys.Rev. D52 (1995) 7011-7026
|
10.1103/PhysRevD.52.7011
|
CTMP/011/NCSU
|
gr-qc hep-th
| null |
Path integral methods are used to derive a general expression for the entropy
of a black hole in a diffeomorphism invariant theory. The result, which depends
on the variational derivative of the Lagrangian with respect to the Riemann
tensor, agrees with the result obtained from Noether charge methods by Iyer and
Wald. The method used here is based on the direct expression of the density of
states as a path integral (the microcanonical functional integral). The
analysis makes crucial use of the Hamiltonian form of the action. An algorithm
for placing the action of a diffeomorphism invariant theory in Hamiltonian form
is presented. Other path integral approaches to the derivation of black hole
entropy include the Hilbert action surface term method and the conical deficit
angle method. The relationships between these path integral methods are
presented.
|
[
{
"created": "Fri, 30 Jun 1995 16:54:58 GMT",
"version": "v1"
}
] |
2009-10-28
|
[
[
"Brown",
"David",
""
]
] |
Path integral methods are used to derive a general expression for the entropy of a black hole in a diffeomorphism invariant theory. The result, which depends on the variational derivative of the Lagrangian with respect to the Riemann tensor, agrees with the result obtained from Noether charge methods by Iyer and Wald. The method used here is based on the direct expression of the density of states as a path integral (the microcanonical functional integral). The analysis makes crucial use of the Hamiltonian form of the action. An algorithm for placing the action of a diffeomorphism invariant theory in Hamiltonian form is presented. Other path integral approaches to the derivation of black hole entropy include the Hilbert action surface term method and the conical deficit angle method. The relationships between these path integral methods are presented.
|
gr-qc/0007058
|
Mario La Camera
|
A. G. Agnese, M. La Camera
|
Black hole horizon and space-time foam
|
8 pages, LateX2e
|
Nuovo Cim.B116:611-615,2001
| null | null |
gr-qc
| null |
We introduce, by means of the Brans-Dicke scalar field, space-time
fluctuations at scale comparable to Planck length near the event horizon of a
black hole and examine their dramatic effects.
|
[
{
"created": "Fri, 21 Jul 2000 16:28:27 GMT",
"version": "v1"
}
] |
2010-11-11
|
[
[
"Agnese",
"A. G.",
""
],
[
"La Camera",
"M.",
""
]
] |
We introduce, by means of the Brans-Dicke scalar field, space-time fluctuations at scale comparable to Planck length near the event horizon of a black hole and examine their dramatic effects.
|
2401.02260
|
Ran Li
|
Ran Li, Conghua Liu, Jin Wang
|
Phase space path integral approach to the kinetics of black hole phase
transition
|
More discussions on generalized free energy from York's approach and
phase portrait at the critical point, and a brief review of time-dependent
Ginzburg-Landau model are added
| null | null | null |
gr-qc cond-mat.stat-mech hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We employ the approach of path integral in the phase space to study the
kinetics of state switching associated with black hole phase transitions. Under
the assumption that the state switching process of the black hole is described
by the stochastic Langevin equation based on the free energy landscape, we
derived the Martin-Siggia-Rose-Janssen-de Dominicis (MSRJD) functional and
obtained the path integral expression of the transition probability. The MSRJD
functional inherently represents the path integral in the phase space, allowing
us to extract the effective Hamiltonian for the dynamics of state switching
process. By solving the Hamiltonian equations of motion, we obtain the kinetic
path in the phase space using an example of the RNAdS black hole. Furthermore,
the dominant kinetic path within the configuration space is calculated. We also
discuss the kinetic rate by using the functional formalism. Finally, we examine
two further examples: Hawking-Page phase transition and Gauss-Bonnet black hole
phase transition at the triple point. Our analysis demonstrates that,
concerning the Hawking-Page phase transition, while a dominant kinetic path in
the phase space from the large SAdS black hole to the thermal AdS space is
present, there is no kinetic path for the inverse process. For the Gauss-Bonnet
black hole phase transition at the triple point, the state switching processes
between the small, the intermediate and the large Gauss-Bonnet black holes
constitute a chemical reaction cycle.
|
[
{
"created": "Thu, 4 Jan 2024 13:27:13 GMT",
"version": "v1"
},
{
"created": "Fri, 5 Jan 2024 13:01:06 GMT",
"version": "v2"
},
{
"created": "Mon, 6 May 2024 12:41:04 GMT",
"version": "v3"
},
{
"created": "Tue, 7 May 2024 02:19:05 GMT",
"version": "v4"
}
] |
2024-05-08
|
[
[
"Li",
"Ran",
""
],
[
"Liu",
"Conghua",
""
],
[
"Wang",
"Jin",
""
]
] |
We employ the approach of path integral in the phase space to study the kinetics of state switching associated with black hole phase transitions. Under the assumption that the state switching process of the black hole is described by the stochastic Langevin equation based on the free energy landscape, we derived the Martin-Siggia-Rose-Janssen-de Dominicis (MSRJD) functional and obtained the path integral expression of the transition probability. The MSRJD functional inherently represents the path integral in the phase space, allowing us to extract the effective Hamiltonian for the dynamics of state switching process. By solving the Hamiltonian equations of motion, we obtain the kinetic path in the phase space using an example of the RNAdS black hole. Furthermore, the dominant kinetic path within the configuration space is calculated. We also discuss the kinetic rate by using the functional formalism. Finally, we examine two further examples: Hawking-Page phase transition and Gauss-Bonnet black hole phase transition at the triple point. Our analysis demonstrates that, concerning the Hawking-Page phase transition, while a dominant kinetic path in the phase space from the large SAdS black hole to the thermal AdS space is present, there is no kinetic path for the inverse process. For the Gauss-Bonnet black hole phase transition at the triple point, the state switching processes between the small, the intermediate and the large Gauss-Bonnet black holes constitute a chemical reaction cycle.
|
1703.07440
|
Anatoly Svidzinsky
|
Anatoly Svidzinsky
|
Testing Vector Gravity with Gravitational Wave Interferometers
|
4 pages, 2 figures
|
Published as Section 16 in Physica Scripta 92, 125001 (2017)
|
10.1088/1402-4896/aa93a8
| null |
gr-qc astro-ph.CO astro-ph.HE hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Recently, the author proposed an alternative vector theory of gravity. To the
best of our knowledge, vector gravity also passes available tests of gravity,
and, in addition, predicts the correct value of the cosmological constant
without free parameters. It is important to find a new feasible test which can
distinguish between vector gravity and general relativity and determine whether
gravity has a vector or a tensor origin. Here we propose such an experiment
based on measurement of propagation direction of gravitational waves relative
to the perpendicular arms of a laser interferometer. We show that transverse
gravitational wave in vector gravity produces no signal when it propagates in
the direction perpendicular to the interferometer plane or along one of the
arms. In contrast, general relativistic wave yields no signal when it
propagates parallel to the interferometer plane at $45^{\circ }$ angle relative
to an interferometer arm. The test can be performed in the nearest years in a
joint run of the two LIGO and one Virgo interferometers.
|
[
{
"created": "Tue, 21 Mar 2017 21:40:19 GMT",
"version": "v1"
}
] |
2017-11-21
|
[
[
"Svidzinsky",
"Anatoly",
""
]
] |
Recently, the author proposed an alternative vector theory of gravity. To the best of our knowledge, vector gravity also passes available tests of gravity, and, in addition, predicts the correct value of the cosmological constant without free parameters. It is important to find a new feasible test which can distinguish between vector gravity and general relativity and determine whether gravity has a vector or a tensor origin. Here we propose such an experiment based on measurement of propagation direction of gravitational waves relative to the perpendicular arms of a laser interferometer. We show that transverse gravitational wave in vector gravity produces no signal when it propagates in the direction perpendicular to the interferometer plane or along one of the arms. In contrast, general relativistic wave yields no signal when it propagates parallel to the interferometer plane at $45^{\circ }$ angle relative to an interferometer arm. The test can be performed in the nearest years in a joint run of the two LIGO and one Virgo interferometers.
|
2104.08722
|
Alberto Escalante
|
A. Escalante (Puebla U., Inst. Fis.) and Jorge Hern\'andez Aguilar
(FCFM, BUAP)
|
New canonical analysis for higher order topologically massive gravity
| null | null |
10.1140/epjc/s10052-021-09429-6
| null |
gr-qc math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A detailed Gitman-Lyakhovich-Tyutin analysis for higher-order topologically
massive gravity is performed. The full structure of the constraints, the
counting of physical degrees of freedom, and the Dirac algebra among the
constraints are reported. Moreover, our analysis presents a new structure of
the constraints and we compare our results with those reported in the
literature where a standard Ostrogradski framework was developed.
|
[
{
"created": "Sun, 18 Apr 2021 05:25:05 GMT",
"version": "v1"
},
{
"created": "Sun, 30 May 2021 21:55:46 GMT",
"version": "v2"
},
{
"created": "Fri, 18 Jun 2021 16:42:59 GMT",
"version": "v3"
}
] |
2021-08-18
|
[
[
"Escalante",
"A.",
"",
"Puebla U., Inst. Fis."
],
[
"Aguilar",
"Jorge Hernández",
"",
"FCFM, BUAP"
]
] |
A detailed Gitman-Lyakhovich-Tyutin analysis for higher-order topologically massive gravity is performed. The full structure of the constraints, the counting of physical degrees of freedom, and the Dirac algebra among the constraints are reported. Moreover, our analysis presents a new structure of the constraints and we compare our results with those reported in the literature where a standard Ostrogradski framework was developed.
|
0910.2498
|
Roman Sverdlov
|
Roman Sverdlov
|
Causal set as a discretized phase spacetime
|
50 pages, no figures
| null | null | null |
gr-qc math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The first goal of this paper is to show that discreteness, locality, and
relativistic covariance can peacefully coexist if the ordinary spacetime (OST)
is replaced with phase spacetime (PST) as a geometric background of a Poisson
process, where PST is a spacetime generalization of a notion of phase space
(this is a 7-dimensional version of the 8-dimensional structure proposed by
Caianiello). Furthermore, Caianiello's idea of finite acceleration is
implemented. After this is done, the paper then goes on to generalize the
geometric notions obtained from the intuition of PST to a general discrete
causal set, without any geometric background. It then takes advantage of the
absence of lightcone singularity to attempt to tackle the definition of
PST-like causal set; that is, a discrete system that approximates the
geometrical properties that we would expect from continuum PST. Finally, the
paper proceeds to introduce quantum field theory on a causal set, and shows
that the locality gained by switching from OST to PST brings us one step closer
to be able to treat quantum field theory on a causal set analytically rather
than numerically.
|
[
{
"created": "Tue, 13 Oct 2009 23:54:06 GMT",
"version": "v1"
},
{
"created": "Mon, 2 Nov 2009 18:25:35 GMT",
"version": "v2"
},
{
"created": "Fri, 30 Apr 2010 03:24:54 GMT",
"version": "v3"
}
] |
2010-05-03
|
[
[
"Sverdlov",
"Roman",
""
]
] |
The first goal of this paper is to show that discreteness, locality, and relativistic covariance can peacefully coexist if the ordinary spacetime (OST) is replaced with phase spacetime (PST) as a geometric background of a Poisson process, where PST is a spacetime generalization of a notion of phase space (this is a 7-dimensional version of the 8-dimensional structure proposed by Caianiello). Furthermore, Caianiello's idea of finite acceleration is implemented. After this is done, the paper then goes on to generalize the geometric notions obtained from the intuition of PST to a general discrete causal set, without any geometric background. It then takes advantage of the absence of lightcone singularity to attempt to tackle the definition of PST-like causal set; that is, a discrete system that approximates the geometrical properties that we would expect from continuum PST. Finally, the paper proceeds to introduce quantum field theory on a causal set, and shows that the locality gained by switching from OST to PST brings us one step closer to be able to treat quantum field theory on a causal set analytically rather than numerically.
|
2310.08781
|
Joel Saavedra
|
Joel Saavedra and Francisco Tello-Ortiz
|
Unified first law of thermodynamics in Gauss-Bonnet gravity on an FLRW
background
|
10 pages, 2 figures
| null | null | null |
gr-qc hep-th
|
http://creativecommons.org/licenses/by/4.0/
|
Employing the thermodynamic unified first law through the
thermodynamic-gravity conjecture, in this article, we derive for a FLRW
universe the Friedmann equations in the framework of Gauss-Bonnet gravity
theory. To do this, we project this generalized first law along the Kodama
vector field and along the direction of an orthogonal vector to the Kodama
vector. The second Friedmann equation is obtained by projecting on the Kodama
vector, while the first is obtained by projecting along the flux on the Cauchy
hypersurfaces. This result does not assume a priory temperature and an entropy,
so the Clausius relation is not used here. Nevertheless, it is used to obtain
the corresponding Gauss-Bonnet entropy. In this way, the validity of the
generalized second law of thermodynamics is proved for the Gauss-Bonnet gravity
theory.
|
[
{
"created": "Fri, 13 Oct 2023 00:06:56 GMT",
"version": "v1"
}
] |
2023-10-16
|
[
[
"Saavedra",
"Joel",
""
],
[
"Tello-Ortiz",
"Francisco",
""
]
] |
Employing the thermodynamic unified first law through the thermodynamic-gravity conjecture, in this article, we derive for a FLRW universe the Friedmann equations in the framework of Gauss-Bonnet gravity theory. To do this, we project this generalized first law along the Kodama vector field and along the direction of an orthogonal vector to the Kodama vector. The second Friedmann equation is obtained by projecting on the Kodama vector, while the first is obtained by projecting along the flux on the Cauchy hypersurfaces. This result does not assume a priory temperature and an entropy, so the Clausius relation is not used here. Nevertheless, it is used to obtain the corresponding Gauss-Bonnet entropy. In this way, the validity of the generalized second law of thermodynamics is proved for the Gauss-Bonnet gravity theory.
|
1102.2720
|
Jian-Yang Zhu
|
Yu Li and Jian-Yang Zhu
|
Application of higher order holonomy corrections to perturbation theory
of cosmology
|
7 pages, 1 figures
|
Class.Quant.Grav.28:045007,2011
|
10.1088/0264-9381/28/4/045007
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Applying the higher order holonomy corrections to the perturbation theory of
cosmology, the lattice power law of Loop Quantum Cosmology, $\tilde{\mu}\propto
p^{\beta}$, is analysed and the range of $\beta$ is decided to be [-1,0] which
is different from the conventional range $-0.1319>\beta\geq-5/2$ \cite{lqct}.
At the same time, we find that there is a anomaly free condition in this
theory, and we obtain this condition in the vector and tensor mode. We also
find that the nonzero mass of gravitational wave essentially results from the
quantum nature of Riemannian geometry of loop quantum gravity.
|
[
{
"created": "Mon, 14 Feb 2011 10:22:32 GMT",
"version": "v1"
}
] |
2011-09-08
|
[
[
"Li",
"Yu",
""
],
[
"Zhu",
"Jian-Yang",
""
]
] |
Applying the higher order holonomy corrections to the perturbation theory of cosmology, the lattice power law of Loop Quantum Cosmology, $\tilde{\mu}\propto p^{\beta}$, is analysed and the range of $\beta$ is decided to be [-1,0] which is different from the conventional range $-0.1319>\beta\geq-5/2$ \cite{lqct}. At the same time, we find that there is a anomaly free condition in this theory, and we obtain this condition in the vector and tensor mode. We also find that the nonzero mass of gravitational wave essentially results from the quantum nature of Riemannian geometry of loop quantum gravity.
|
gr-qc/0101065
|
Kouji Nakamura
|
Kouji Nakamura
|
Initial condition of a thick loop cosmic string and linear perturbations
|
21 pages, 4 figures, RevTeX. Some spelling / grammar typos are
corrected. Accepted for publication in Classical and Quantum Gravity
|
Class.Quant.Grav. 19 (2002) 783-798
|
10.1088/0264-9381/19/4/310
|
NAOJ-Th-Ap 2001, No.71
|
gr-qc
| null |
The initial data of the gravitational field produced by a loop thick string
is considered. We show that a thick loop is not a geodesic on the initial
hypersurface, while a loop conical singularity is. This suggests that there is
the ``{\it critical thickness}'' of a string, at which the linear perturbation
theory with a flat space background fails to describe the gravity of a loop
cosmic string. Using the above initial data, we also show that the linear
perturbation around flat space is plausible if the string thickness is larger
than $\sim5\times10^{-3}a$, where $a$ is the curvature radius of the loop.
|
[
{
"created": "Wed, 17 Jan 2001 07:22:52 GMT",
"version": "v1"
},
{
"created": "Fri, 11 May 2001 08:19:32 GMT",
"version": "v2"
},
{
"created": "Tue, 3 Jul 2001 06:45:15 GMT",
"version": "v3"
},
{
"created": "Mon, 7 Jan 2002 05:39:16 GMT",
"version": "v4"
}
] |
2009-11-07
|
[
[
"Nakamura",
"Kouji",
""
]
] |
The initial data of the gravitational field produced by a loop thick string is considered. We show that a thick loop is not a geodesic on the initial hypersurface, while a loop conical singularity is. This suggests that there is the ``{\it critical thickness}'' of a string, at which the linear perturbation theory with a flat space background fails to describe the gravity of a loop cosmic string. Using the above initial data, we also show that the linear perturbation around flat space is plausible if the string thickness is larger than $\sim5\times10^{-3}a$, where $a$ is the curvature radius of the loop.
|
1807.03000
|
J\"urgen Struckmeier
|
J\"urgen Struckmeier, David Vasak, Johannes Kirsch
|
Generic Theory of Geometrodynamics from Noether's theorem for the
Diff(M) symmetry group
|
40 pages
|
In: Kirsch J., Schramm S., Steinheimer-Froschauer J., St\"ocker H.
(eds) Discoveries at the Frontiers of Science. FIAS Interdisciplinary Science
Series. Springer, Cham. (2020)
|
10.1007/978-3-030-34234-0_12
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We work out the most general theory for the interaction of spacetime geometry
and matter fields -- commonly referred to as geometrodynamics -- for spin-$0$
and spin-$1$ particles. The minimum set of postulates to be introduced is that
(i) the action principle should apply and that(ii) the total action should by
form-invariant under the (local) diffeomorphism group. The second postulate
thus implements the Principle of General Relativity. According to Noether's
theorem, this physical symmetry gives rise to a conserved Noether current, from
which the complete set of theories compatible with both postulates can be
deduced. This finally results in a new generic Einstein-type equation, which
can be interpreted as an energy-momentum balance equation emerging from the
Lagrangian $L_{R}$ for the source-free dynamics of gravitation and the
energy-momentum tensor of the source system $L_{0}$. Provided that the system
has no other symmetries -- such as SU$(N)$ -- the canonical energy-momentum
tensor turns out to be the correct source term of gravitation. For the case of
massive spin particles, this entails an increased weighting of the kinetic
energy over the mass in their roles as the source of gravity as compared to the
metric energy momentum tensor, which constitutes the source of gravity in
Einstein's General Relativity. We furthermore confirm that a massive vector
field necessarily acts as a source for torsion of spacetime. Thus, from the
viewpoint of our generic Einstein-type equation, Einstein's General Relativity
constitutes the particular case for spin-$0$ and massless spin particle fields,
and the Hilbert Lagrangian $L_{R,H}$ as the model for the source-free dynamics
of gravitation.
|
[
{
"created": "Mon, 9 Jul 2018 09:24:49 GMT",
"version": "v1"
},
{
"created": "Fri, 2 Aug 2019 12:20:19 GMT",
"version": "v10"
},
{
"created": "Fri, 6 Sep 2019 15:41:50 GMT",
"version": "v11"
},
{
"created": "Sun, 18 Apr 2021 19:45:40 GMT",
"version": "v12"
},
{
"created": "Wed, 5 Oct 2022 15:39:50 GMT",
"version": "v13"
},
{
"created": "Thu, 8 Nov 2018 10:53:58 GMT",
"version": "v2"
},
{
"created": "Wed, 6 Mar 2019 14:33:04 GMT",
"version": "v3"
},
{
"created": "Mon, 1 Apr 2019 12:09:50 GMT",
"version": "v4"
},
{
"created": "Thu, 2 May 2019 12:14:34 GMT",
"version": "v5"
},
{
"created": "Mon, 27 May 2019 14:31:45 GMT",
"version": "v6"
},
{
"created": "Wed, 12 Jun 2019 14:47:50 GMT",
"version": "v7"
},
{
"created": "Mon, 8 Jul 2019 08:33:42 GMT",
"version": "v8"
},
{
"created": "Wed, 24 Jul 2019 10:59:55 GMT",
"version": "v9"
}
] |
2022-10-06
|
[
[
"Struckmeier",
"Jürgen",
""
],
[
"Vasak",
"David",
""
],
[
"Kirsch",
"Johannes",
""
]
] |
We work out the most general theory for the interaction of spacetime geometry and matter fields -- commonly referred to as geometrodynamics -- for spin-$0$ and spin-$1$ particles. The minimum set of postulates to be introduced is that (i) the action principle should apply and that(ii) the total action should by form-invariant under the (local) diffeomorphism group. The second postulate thus implements the Principle of General Relativity. According to Noether's theorem, this physical symmetry gives rise to a conserved Noether current, from which the complete set of theories compatible with both postulates can be deduced. This finally results in a new generic Einstein-type equation, which can be interpreted as an energy-momentum balance equation emerging from the Lagrangian $L_{R}$ for the source-free dynamics of gravitation and the energy-momentum tensor of the source system $L_{0}$. Provided that the system has no other symmetries -- such as SU$(N)$ -- the canonical energy-momentum tensor turns out to be the correct source term of gravitation. For the case of massive spin particles, this entails an increased weighting of the kinetic energy over the mass in their roles as the source of gravity as compared to the metric energy momentum tensor, which constitutes the source of gravity in Einstein's General Relativity. We furthermore confirm that a massive vector field necessarily acts as a source for torsion of spacetime. Thus, from the viewpoint of our generic Einstein-type equation, Einstein's General Relativity constitutes the particular case for spin-$0$ and massless spin particle fields, and the Hilbert Lagrangian $L_{R,H}$ as the model for the source-free dynamics of gravitation.
|
1212.3987
|
Nils Andersson
|
N. Andersson, C. Krueger, G. L. Comer and L. Samuelsson
|
A minimal model for finite temperature superfluid dynamics
|
RevTeX, 1 eps figure
| null |
10.1088/0264-9381/30/23/235025
| null |
gr-qc astro-ph.SR
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Building on a recently improved understanding of the problem of heat flow in
general relativity, we develop a hydrodynamical model for coupled finite
temperature superfluids. The formalism is designed with the dynamics of the
outer core of a mature neutron star (where superfluid neutrons are coupled to a
conglomerate of protons and electrons) in mind, but the main ingredients are
relevant for a range of analogous problems. The entrainment between material
fluid components (the condensates) and the entropy (the thermal excitations)
plays a central role in the development. We compare and contrast the new model
to previous results in the literature, and provide estimates for the relevant
entrainment coefficients that should prove useful in future applications.
Finally, we consider the sound-wave propagation in the system in two simple
limits, demonstrating the presence of second sound if the temperature is
sub-critical, but absence of this phenomenon above the critical temperature for
superfluidity.
|
[
{
"created": "Mon, 17 Dec 2012 13:38:33 GMT",
"version": "v1"
}
] |
2015-06-12
|
[
[
"Andersson",
"N.",
""
],
[
"Krueger",
"C.",
""
],
[
"Comer",
"G. L.",
""
],
[
"Samuelsson",
"L.",
""
]
] |
Building on a recently improved understanding of the problem of heat flow in general relativity, we develop a hydrodynamical model for coupled finite temperature superfluids. The formalism is designed with the dynamics of the outer core of a mature neutron star (where superfluid neutrons are coupled to a conglomerate of protons and electrons) in mind, but the main ingredients are relevant for a range of analogous problems. The entrainment between material fluid components (the condensates) and the entropy (the thermal excitations) plays a central role in the development. We compare and contrast the new model to previous results in the literature, and provide estimates for the relevant entrainment coefficients that should prove useful in future applications. Finally, we consider the sound-wave propagation in the system in two simple limits, demonstrating the presence of second sound if the temperature is sub-critical, but absence of this phenomenon above the critical temperature for superfluidity.
|
gr-qc/0606017
|
Alexander Kaganovich B.
|
E. I. Guendelman and A. B. Kaganovich
|
k-Essence, Avoidance of the Weinberg's Cosmological Constant No-Go
Theorem and Other Dark Energy Effects of Two Measures Field Theory
|
25 pages, 11 figures; more detailed and improved explanation
presented on how the Weinberg's no-go theorem is avoided; references added
| null | null | null |
gr-qc astro-ph hep-th
| null |
The dilaton-gravity sector of the Two Measures Field Theory (TMT) is explored
in detail in the context of cosmology. The dilaton \phi dependence of the
effective Lagrangian appears only as a result of the spontaneous breakdown of
the scale invariance. If no fine tuning is made, the effective \phi-Lagrangian
p(\phi,X) depends quadratically upon the kinetic energy X. Hence TMT may
represent an explicit example of the effective k-essence resulting from first
principles without any exotic term in the fundamental action intended for
obtaining this result. Depending of the choice of regions in the parameter
space, TMT exhibits different possible outputs for cosmological dynamics: a)
Possibility of resolution of the old cosmological constant (CC) problem. From
the point of view of TMT, it becomes clear why the old CC problem cannot be
solved (without fine tuning) in the conventional field theories (i.e theories
with only the measure of integration \sqrt{-g} in the action). b) The power law
inflation without any fine tuning can end with damped oscillations of \phi
around the state with zero CC. d) There is a broad range of the parameters such
that: in the late time universe w=p/\rho <-1 and asymptotically (as t\to\infty)
approaches -1 from below; \rho approaches a cosmological constant. The
smallness of the CC may be achieved without fine tuning of dimensionfull
parameters: either by a seesaw type mechanism or due to a correspondence
principle between TMT and conventional field theories.
|
[
{
"created": "Sun, 4 Jun 2006 13:05:53 GMT",
"version": "v1"
},
{
"created": "Wed, 21 Jun 2006 11:08:37 GMT",
"version": "v2"
}
] |
2007-05-23
|
[
[
"Guendelman",
"E. I.",
""
],
[
"Kaganovich",
"A. B.",
""
]
] |
The dilaton-gravity sector of the Two Measures Field Theory (TMT) is explored in detail in the context of cosmology. The dilaton \phi dependence of the effective Lagrangian appears only as a result of the spontaneous breakdown of the scale invariance. If no fine tuning is made, the effective \phi-Lagrangian p(\phi,X) depends quadratically upon the kinetic energy X. Hence TMT may represent an explicit example of the effective k-essence resulting from first principles without any exotic term in the fundamental action intended for obtaining this result. Depending of the choice of regions in the parameter space, TMT exhibits different possible outputs for cosmological dynamics: a) Possibility of resolution of the old cosmological constant (CC) problem. From the point of view of TMT, it becomes clear why the old CC problem cannot be solved (without fine tuning) in the conventional field theories (i.e theories with only the measure of integration \sqrt{-g} in the action). b) The power law inflation without any fine tuning can end with damped oscillations of \phi around the state with zero CC. d) There is a broad range of the parameters such that: in the late time universe w=p/\rho <-1 and asymptotically (as t\to\infty) approaches -1 from below; \rho approaches a cosmological constant. The smallness of the CC may be achieved without fine tuning of dimensionfull parameters: either by a seesaw type mechanism or due to a correspondence principle between TMT and conventional field theories.
|
1003.0597
|
Alessandro Nagar
|
Sebastiano Bernuzzi, Alessandro Nagar
|
Binary black hole merger in the extreme-mass-ratio limit: a multipolar
analysis
|
20 pages, 12 figures. Version published in Phys. Rev. D
|
Phys.Rev.D81:084056,2010
|
10.1103/PhysRevD.81.084056
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Building up on previous work, we present a new calculation of the
gravitational wave (GW) emission generated during the transition from
quasi-circular inspiral to plunge, merger and ringdown by a binary system of
nonspinning black holes, of masses $m_1$ and $m_2$, in the extreme mass ratio
limit, $m_1 m_2\ll(m_1+m_2)^2$. The relative dynamics of the system is computed
{\it without making any adiabatic approximation} by using an effective one body
(EOB) description, namely by representing the binary by an effective particle
of mass $\mu=m_1 m_2/(m_1+m_2)$ moving in a (quasi-)Schwarzschild background of
mass $M=m_1+m_2$ and submitted to an $\O(\nu)$ 5PN-resummed analytical
radiation reaction force, with $\nu=\mu/M$. The gravitational wave emission is
calculated via a multipolar Regge-Wheeler-Zerilli type perturbative approach
(valid in the limit $\nu\ll 1$). We consider three mass ratios,
$\nu={10^{-2},10^{-3},10^{-4}}$,and we compute the multipolar waveform up to
$\ell=8$. We estimate energy and angular momentum losses during the
quasi-universal and quasi-geodesic part of the plunge phase and we analyze the
structure of the ringdown. We calculate the gravitational recoil, or "kick",
imparted to the merger remnant by the gravitational wave emission and we
emphasize the importance of higher multipoles to get a final value of the
recoil $v/(c\nu^2)=0.0446$. We finally show that there is an {\it excellent
fractional agreement} ($\sim 10^{-3}$) (even during the plunge) between the 5PN
EOB analytically-resummed radiation reaction flux and the numerically computed
gravitational wave angular momentum flux. This is a further confirmation of the
aptitude of the EOB formalism to accurately model extreme-mass-ratio inspirals,
as needed for the future space-based LISA gravitational wave detector.
|
[
{
"created": "Tue, 2 Mar 2010 14:10:17 GMT",
"version": "v1"
},
{
"created": "Tue, 14 Dec 2010 13:59:41 GMT",
"version": "v2"
}
] |
2010-12-15
|
[
[
"Bernuzzi",
"Sebastiano",
""
],
[
"Nagar",
"Alessandro",
""
]
] |
Building up on previous work, we present a new calculation of the gravitational wave (GW) emission generated during the transition from quasi-circular inspiral to plunge, merger and ringdown by a binary system of nonspinning black holes, of masses $m_1$ and $m_2$, in the extreme mass ratio limit, $m_1 m_2\ll(m_1+m_2)^2$. The relative dynamics of the system is computed {\it without making any adiabatic approximation} by using an effective one body (EOB) description, namely by representing the binary by an effective particle of mass $\mu=m_1 m_2/(m_1+m_2)$ moving in a (quasi-)Schwarzschild background of mass $M=m_1+m_2$ and submitted to an $\O(\nu)$ 5PN-resummed analytical radiation reaction force, with $\nu=\mu/M$. The gravitational wave emission is calculated via a multipolar Regge-Wheeler-Zerilli type perturbative approach (valid in the limit $\nu\ll 1$). We consider three mass ratios, $\nu={10^{-2},10^{-3},10^{-4}}$,and we compute the multipolar waveform up to $\ell=8$. We estimate energy and angular momentum losses during the quasi-universal and quasi-geodesic part of the plunge phase and we analyze the structure of the ringdown. We calculate the gravitational recoil, or "kick", imparted to the merger remnant by the gravitational wave emission and we emphasize the importance of higher multipoles to get a final value of the recoil $v/(c\nu^2)=0.0446$. We finally show that there is an {\it excellent fractional agreement} ($\sim 10^{-3}$) (even during the plunge) between the 5PN EOB analytically-resummed radiation reaction flux and the numerically computed gravitational wave angular momentum flux. This is a further confirmation of the aptitude of the EOB formalism to accurately model extreme-mass-ratio inspirals, as needed for the future space-based LISA gravitational wave detector.
|
1909.11196
|
Shao-Jiang Wang
|
Shao-Jiang Wang
|
Occurrence of semiclassical vacuum decay
|
v1, 9 pages, 6 figures; v2, to match the published version in PRD,
title slightly changed by editor
|
Phys. Rev. D 100, 096019 (2019)
|
10.1103/PhysRevD.100.096019
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Recently, a novel phenomenon is observed for vacuum decay to proceed via
classically allowed dynamical evolution from initial configurations of false
vacuum fluctuations. With the help of some occasionally developed large
fluctuations in time derivative of a homogeneous scalar field that is initially
sitting at the false vacuum, the flyover vacuum decay is proposed if the
initial Gaussian profile of field velocity contains a spatial region where the
field velocity is large enough to flyover the potential barrier. In this paper,
we point out that, even if the initial profile of field velocity is nowhere to
be large enough to classically overcome the barrier, the semiclassical vacuum
decay could still be possible if the initial profile of field velocity extends
over large enough region.
|
[
{
"created": "Tue, 24 Sep 2019 21:37:00 GMT",
"version": "v1"
},
{
"created": "Tue, 26 Nov 2019 16:41:22 GMT",
"version": "v2"
}
] |
2020-01-16
|
[
[
"Wang",
"Shao-Jiang",
""
]
] |
Recently, a novel phenomenon is observed for vacuum decay to proceed via classically allowed dynamical evolution from initial configurations of false vacuum fluctuations. With the help of some occasionally developed large fluctuations in time derivative of a homogeneous scalar field that is initially sitting at the false vacuum, the flyover vacuum decay is proposed if the initial Gaussian profile of field velocity contains a spatial region where the field velocity is large enough to flyover the potential barrier. In this paper, we point out that, even if the initial profile of field velocity is nowhere to be large enough to classically overcome the barrier, the semiclassical vacuum decay could still be possible if the initial profile of field velocity extends over large enough region.
|
gr-qc/0202077
|
Martin Bojowald
|
Martin Bojowald
|
Isotropic Loop Quantum Cosmology
|
30 pages
|
Class.Quant.Grav. 19 (2002) 2717-2742
|
10.1088/0264-9381/19/10/313
|
CGPG-02/2-2
|
gr-qc hep-th
| null |
Isotropic models in loop quantum cosmology allow explicit calculations,
thanks largely to a completely known volume spectrum, which is exploited in
order to write down the evolution equation in a discrete internal time. Because
of genuinely quantum geometrical effects the classical singularity is absent in
those models in the sense that the evolution does not break down there,
contrary to the classical situation where space-time is inextendible. This
effect is generic and does not depend on matter violating energy conditions,
but it does depend on the factor ordering of the Hamiltonian constraint.
Furthermore, it is shown that loop quantum cosmology reproduces standard
quantum cosmology and hence (e.g., via WKB approximation) to classical behavior
in the large volume regime where the discreteness of space is insignificant.
Finally, an explicit solution to the Euclidean vacuum constraint is discussed
which is the unique solution with semiclassical behavior representing quantum
Euclidean space.
|
[
{
"created": "Thu, 21 Feb 2002 18:43:11 GMT",
"version": "v1"
}
] |
2009-11-07
|
[
[
"Bojowald",
"Martin",
""
]
] |
Isotropic models in loop quantum cosmology allow explicit calculations, thanks largely to a completely known volume spectrum, which is exploited in order to write down the evolution equation in a discrete internal time. Because of genuinely quantum geometrical effects the classical singularity is absent in those models in the sense that the evolution does not break down there, contrary to the classical situation where space-time is inextendible. This effect is generic and does not depend on matter violating energy conditions, but it does depend on the factor ordering of the Hamiltonian constraint. Furthermore, it is shown that loop quantum cosmology reproduces standard quantum cosmology and hence (e.g., via WKB approximation) to classical behavior in the large volume regime where the discreteness of space is insignificant. Finally, an explicit solution to the Euclidean vacuum constraint is discussed which is the unique solution with semiclassical behavior representing quantum Euclidean space.
|
gr-qc/9212004
| null |
A L Matacz, A C Ottewill and P C W Davies
|
Quantum Vacuum Instability Near Rotating Stars
|
17 Pages, (accepted by PRD), (previously incorrect header files have
been corrected)
|
Phys.Rev. D47 (1993) 1557-1562
|
10.1103/PhysRevD.47.1557
| null |
gr-qc
| null |
We discuss the Starobinskii-Unruh process for the Kerr black hole. We show
how this effect is related to the theory of squeezed states. We then consider a
simple model for a highly relativistic rotating star and show that the
Starobinskii-Unruh effect is absent.
|
[
{
"created": "Thu, 3 Dec 1992 19:28:00 GMT",
"version": "v1"
},
{
"created": "Tue, 8 Dec 1992 14:19:00 GMT",
"version": "v2"
}
] |
2009-10-22
|
[
[
"Matacz",
"A L",
""
],
[
"Ottewill",
"A C",
""
],
[
"Davies",
"P C W",
""
]
] |
We discuss the Starobinskii-Unruh process for the Kerr black hole. We show how this effect is related to the theory of squeezed states. We then consider a simple model for a highly relativistic rotating star and show that the Starobinskii-Unruh effect is absent.
|
gr-qc/9901028
|
Dongsu Bak
|
Dongsu Bak, Sang Pyo kim, Sung Ku Kim, Kwang-Sup Soh, and Jae Hyung
Yee
|
Quantum Creation of Black Hole by Tunneling in Scalar Field Collapse
|
t clarification of the quantization method in Sec. IV, version to
appear in PRD
|
Phys.Rev.D60:064005,1999
|
10.1103/PhysRevD.60.064005
| null |
gr-qc
| null |
Continuously self-similar solution of spherically symmetric gravitational
collapse of a scalar field is studied to investigate quantum mechanical black
hole formation by tunneling in the subcritical case where, classically, the
collapse does not produce a black hole.
|
[
{
"created": "Mon, 11 Jan 1999 07:58:28 GMT",
"version": "v1"
},
{
"created": "Fri, 21 May 1999 05:05:09 GMT",
"version": "v2"
}
] |
2010-11-19
|
[
[
"Bak",
"Dongsu",
""
],
[
"kim",
"Sang Pyo",
""
],
[
"Kim",
"Sung Ku",
""
],
[
"Soh",
"Kwang-Sup",
""
],
[
"Yee",
"Jae Hyung",
""
]
] |
Continuously self-similar solution of spherically symmetric gravitational collapse of a scalar field is studied to investigate quantum mechanical black hole formation by tunneling in the subcritical case where, classically, the collapse does not produce a black hole.
|
1202.0719
|
Valerio Faraoni
|
Valerio Faraoni, Andres F. Zambrano Moreno, and Roshina Nandra
|
Making sense of the bizarre behaviour of horizons in the McVittie
spacetime
|
8 pages, 3 figures
| null |
10.1103/PhysRevD.85.083526
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The bizarre behaviour of the apparent (black hole and cosmological) horizons
of the McVittie spacetime is discussed using, as an analogy, the
Schwarzschild-de Sitter-Kottler spacetime (which is a special case of McVittie
anyway). For a dust-dominated "background" universe, a black hole cannot exist
at early times because its (apparent) horizon would be larger than the
cosmological(apparent) horizon. A phantom-dominated "background" universe
causes this situation, and the horizon behaviour, to be time-reversed.
|
[
{
"created": "Fri, 3 Feb 2012 14:41:52 GMT",
"version": "v1"
}
] |
2013-05-30
|
[
[
"Faraoni",
"Valerio",
""
],
[
"Moreno",
"Andres F. Zambrano",
""
],
[
"Nandra",
"Roshina",
""
]
] |
The bizarre behaviour of the apparent (black hole and cosmological) horizons of the McVittie spacetime is discussed using, as an analogy, the Schwarzschild-de Sitter-Kottler spacetime (which is a special case of McVittie anyway). For a dust-dominated "background" universe, a black hole cannot exist at early times because its (apparent) horizon would be larger than the cosmological(apparent) horizon. A phantom-dominated "background" universe causes this situation, and the horizon behaviour, to be time-reversed.
|
0912.0334
|
Leonardo Balart
|
Leonardo Balart
|
Quasilocal Energy, Komar Charge and Horizon for Regular Black Holes
|
10 pages, no figures
|
Phys.Lett.B687:280-285,2010
|
10.1016/j.physletb.2010.03.056
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study the Brown-York quasilocal energy for regular black holes. We also
express the identity that relates the difference of the Brown-York quasilocal
energy and the Komar charge at the horizon to the total energy of the spacetime
for static and spherically symmetric black hole solutions in a convenient way
which permits us to understand why this identity is not satisfied when we
consider nonlinear electrodynamics. However, we give a relation between
quantities evaluated at the horizon and at infinity when nonlinear
electrodynamics is considered. Similar relations are obtained for more general
static and spherically symmetric black hole solutions which include solutions
of dilaton gravity theories.
|
[
{
"created": "Wed, 2 Dec 2009 04:27:17 GMT",
"version": "v1"
}
] |
2014-11-20
|
[
[
"Balart",
"Leonardo",
""
]
] |
We study the Brown-York quasilocal energy for regular black holes. We also express the identity that relates the difference of the Brown-York quasilocal energy and the Komar charge at the horizon to the total energy of the spacetime for static and spherically symmetric black hole solutions in a convenient way which permits us to understand why this identity is not satisfied when we consider nonlinear electrodynamics. However, we give a relation between quantities evaluated at the horizon and at infinity when nonlinear electrodynamics is considered. Similar relations are obtained for more general static and spherically symmetric black hole solutions which include solutions of dilaton gravity theories.
|
gr-qc/9906058
|
Jacob D. Bekenstein
|
Jacob D. Bekenstein
|
Non-Archimedean character of quantum buoyancy and the generalized second
law of thermodynamics
|
RevTeX, 16 pages
|
Phys.Rev. D60 (1999) 124010
|
10.1103/PhysRevD.60.124010
| null |
gr-qc hep-th quant-ph
| null |
Quantum buoyancy has been proposed as the mechanism protecting the
generalized second law when an entropy--bearing object is slowly lowered
towards a black hole and then dropped in. We point out that the original
derivation of the buoyant force from a fluid picture of the acceleration
radiation is invalid unless the object is almost at the horizon, because
otherwise typical wavelengths in the radiation are larger than the object. The
buoyant force is here calculated from the diffractive scattering of waves off
the object, and found to be weaker than in the original theory. As a
consequence, the argument justifying the generalized second law from buoyancy
cannot be completed unless the optimal drop point is next to the horizon. The
universal bound on entropy is always a sufficient condition for operation of
the generalized second law, and can be derived from that law when the optimal
drop point is close to the horizon. We also compute the quantum buoyancy of an
elementary charged particle; it turns out to be negligible for energetic
considerations. Finally, we speculate on the significance of the absence from
the bound of any mention of the number of particle species in nature.
|
[
{
"created": "Wed, 16 Jun 1999 09:05:01 GMT",
"version": "v1"
}
] |
2009-10-31
|
[
[
"Bekenstein",
"Jacob D.",
""
]
] |
Quantum buoyancy has been proposed as the mechanism protecting the generalized second law when an entropy--bearing object is slowly lowered towards a black hole and then dropped in. We point out that the original derivation of the buoyant force from a fluid picture of the acceleration radiation is invalid unless the object is almost at the horizon, because otherwise typical wavelengths in the radiation are larger than the object. The buoyant force is here calculated from the diffractive scattering of waves off the object, and found to be weaker than in the original theory. As a consequence, the argument justifying the generalized second law from buoyancy cannot be completed unless the optimal drop point is next to the horizon. The universal bound on entropy is always a sufficient condition for operation of the generalized second law, and can be derived from that law when the optimal drop point is close to the horizon. We also compute the quantum buoyancy of an elementary charged particle; it turns out to be negligible for energetic considerations. Finally, we speculate on the significance of the absence from the bound of any mention of the number of particle species in nature.
|
2302.06201
|
Ran Li
|
Ran Li, Conghua Liu, Kun Zhang, Jin Wang
|
Topology of the landscape and dominant kinetic path for the
thermodynamic phase transition of the charged Gauss-Bonnet AdS black holes
| null | null |
10.1103/PhysRevD.108.044003
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study the generalized free energy of the five dimensional charged
Gauss-Bonnet AdS black holes in the grand canonical ensemble by treating the
black hole radius and the charge as the order parameters. On the two
dimensional free energy landscape, the lowest points in the basins represent
the local stable black holes and the saddle point represents the unstable black
hole. We show that black hole is the topological defect of gradient field of
the landscape. The black hole stability is determined by the topography of the
free energy landscape in terms of the basin depths and the barrier height
between the basins and is not by the topology of the gradient field. In
addition, we study the stochastic dynamics of the black hole phase transition
and obtain the dominant kinetic path for the transition on the free energy
landscape. Unlike the one dimensional landscape, the dominant kinetic path
between the small and the large black hole state does not necessarily pass
through the intermediate black hole state. Furthermore, the inhomogeneity in
diffusions can lead to the switching from the coupled cooperative process of
black hole phase transition to the decoupled sequential process, giving
different kinetic mechanisms.
|
[
{
"created": "Mon, 13 Feb 2023 09:17:34 GMT",
"version": "v1"
}
] |
2023-08-16
|
[
[
"Li",
"Ran",
""
],
[
"Liu",
"Conghua",
""
],
[
"Zhang",
"Kun",
""
],
[
"Wang",
"Jin",
""
]
] |
We study the generalized free energy of the five dimensional charged Gauss-Bonnet AdS black holes in the grand canonical ensemble by treating the black hole radius and the charge as the order parameters. On the two dimensional free energy landscape, the lowest points in the basins represent the local stable black holes and the saddle point represents the unstable black hole. We show that black hole is the topological defect of gradient field of the landscape. The black hole stability is determined by the topography of the free energy landscape in terms of the basin depths and the barrier height between the basins and is not by the topology of the gradient field. In addition, we study the stochastic dynamics of the black hole phase transition and obtain the dominant kinetic path for the transition on the free energy landscape. Unlike the one dimensional landscape, the dominant kinetic path between the small and the large black hole state does not necessarily pass through the intermediate black hole state. Furthermore, the inhomogeneity in diffusions can lead to the switching from the coupled cooperative process of black hole phase transition to the decoupled sequential process, giving different kinetic mechanisms.
|
gr-qc/0207070
|
Jose Luis Cortes
|
J.L. Alonso, J.L. Cortes, V. Laliena
|
Does a relativistic metric generalization of Newtonian gravity exist in
2+1 dimensions?
|
6 pages, no figures, Revtex4. Some discussions on the physical nature
of the interior solution and on the omega->infinity limit and some references
added. Version to appear in Phys. Rev. D
|
Phys.Rev. D67 (2003) 024023
|
10.1103/PhysRevD.67.024023
| null |
gr-qc hep-th
| null |
It is shown that, contrary to previous claims, a scalar tensor theory of
Brans-Dicke type provides a relativistic generalization of Newtonian gravity in
2+1 dimensions. The theory is metric and test particles follow the space-time
geodesics. The static isotropic solution is studied in vacuum and in regions
filled with an incompressible perfect fluid. It is shown that the solutions can
be consistently matched at the matter vacuum interface, and that the Newtonian
behavior is recovered in the weak field regime.
|
[
{
"created": "Thu, 18 Jul 2002 11:58:06 GMT",
"version": "v1"
},
{
"created": "Mon, 16 Dec 2002 14:14:06 GMT",
"version": "v2"
}
] |
2012-03-15
|
[
[
"Alonso",
"J. L.",
""
],
[
"Cortes",
"J. L.",
""
],
[
"Laliena",
"V.",
""
]
] |
It is shown that, contrary to previous claims, a scalar tensor theory of Brans-Dicke type provides a relativistic generalization of Newtonian gravity in 2+1 dimensions. The theory is metric and test particles follow the space-time geodesics. The static isotropic solution is studied in vacuum and in regions filled with an incompressible perfect fluid. It is shown that the solutions can be consistently matched at the matter vacuum interface, and that the Newtonian behavior is recovered in the weak field regime.
|
1709.03960
|
Masooma Ali
|
Masooma Ali and Sanjeev S. Seahra
|
Natural Inflation from Polymer Quantization
|
9 pages, 4 figures, references added
|
Phys. Rev. D 96, 103524 (2017)
|
10.1103/PhysRevD.96.103524
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study the polymer quantization of a homogeneous massive scalar field in
the early universe using a prescription inequivalent to those previously
appearing in the literature. Specifically, we assume a Hilbert space for which
the scalar field momentum is well defined but its amplitude is not. This is
closer in spirit to the quantization scheme of loop quantum gravity, in which
no unique configuration operator exists. We show that in the semi-classical
approximation, the main effect of this polymer quantization scheme is to
compactify the phase space of chaotic inflation in the field amplitude
direction. This gives rise to an effective scalar potential closely resembling
that of hybrid natural inflation. Unlike polymer schemes in which the scalar
field amplitude is well-defined, the semi-classical dynamics involves a past
cosmological singularity; i.e., this approach does not mitigate the big bang.
|
[
{
"created": "Tue, 12 Sep 2017 17:18:21 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Sep 2017 16:01:56 GMT",
"version": "v2"
},
{
"created": "Thu, 26 Oct 2017 18:07:40 GMT",
"version": "v3"
}
] |
2017-11-22
|
[
[
"Ali",
"Masooma",
""
],
[
"Seahra",
"Sanjeev S.",
""
]
] |
We study the polymer quantization of a homogeneous massive scalar field in the early universe using a prescription inequivalent to those previously appearing in the literature. Specifically, we assume a Hilbert space for which the scalar field momentum is well defined but its amplitude is not. This is closer in spirit to the quantization scheme of loop quantum gravity, in which no unique configuration operator exists. We show that in the semi-classical approximation, the main effect of this polymer quantization scheme is to compactify the phase space of chaotic inflation in the field amplitude direction. This gives rise to an effective scalar potential closely resembling that of hybrid natural inflation. Unlike polymer schemes in which the scalar field amplitude is well-defined, the semi-classical dynamics involves a past cosmological singularity; i.e., this approach does not mitigate the big bang.
|
1703.00844
|
Wolfgang Graf
|
Wolfgang Graf
|
Existence and Stability of Circular Orbits in Time-Dependent Spherically
Symmetric Spacetimes
|
24 pages, 1 figure, slightly reworked and expanded - main results
unchanged
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
For a general spherically four--dimensional metric the notion of
"circularity" of a family of equatorial geodesic trajectories is defined in
geometrical terms. The main object turns out to be the angular--momentum
function $J$ obeying a consistency condition involving the mean extrinsic
curvature of the submanifold containing the geodesics. The ana\-ly\-sis of
linear stability is reduced to a simple dynamical system formally describing a
damped harmonic oscillator. For static metrics the existence of such geodesics
is given when $J^2 > 0$, and $(J^2)' > 0$ for stability. The formalism is then
applied to the Schwarzschild--de Sitter solution, both in its static and in its
time--dependent cosmological version, as well to the Kerr--de Sitter solution.
In addition we present an approximate solution to a cosmological metric
containing a massive source and solving the Einstein field equation for a
massless scalar.
|
[
{
"created": "Thu, 2 Mar 2017 16:10:21 GMT",
"version": "v1"
},
{
"created": "Thu, 9 Mar 2017 14:41:50 GMT",
"version": "v2"
},
{
"created": "Thu, 27 Apr 2017 12:18:09 GMT",
"version": "v3"
},
{
"created": "Thu, 11 May 2017 12:18:34 GMT",
"version": "v4"
},
{
"created": "Wed, 7 Jun 2017 10:55:49 GMT",
"version": "v5"
}
] |
2017-06-08
|
[
[
"Graf",
"Wolfgang",
""
]
] |
For a general spherically four--dimensional metric the notion of "circularity" of a family of equatorial geodesic trajectories is defined in geometrical terms. The main object turns out to be the angular--momentum function $J$ obeying a consistency condition involving the mean extrinsic curvature of the submanifold containing the geodesics. The ana\-ly\-sis of linear stability is reduced to a simple dynamical system formally describing a damped harmonic oscillator. For static metrics the existence of such geodesics is given when $J^2 > 0$, and $(J^2)' > 0$ for stability. The formalism is then applied to the Schwarzschild--de Sitter solution, both in its static and in its time--dependent cosmological version, as well to the Kerr--de Sitter solution. In addition we present an approximate solution to a cosmological metric containing a massive source and solving the Einstein field equation for a massless scalar.
|
1102.3863
|
Ozcan Sert
|
Tekin Dereli and \"Ozcan Sert
|
Non-minimal $\ln(R)F^2$ Couplings of Electromagnetic Fields to Gravity:
Static, Spherically Symmetric Solutions
|
12 pages, 5 figures, accepted for publication in EPJC
|
Eur.Phys.J.C71:1589,2011
|
10.1140/epjc/s10052-011-1589-2
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We investigate the non-minimal couplings between the electromagnetic fields
and gravity through the natural logarithm of the curvature scalar. After we
give the Lagrangian formulation of the non-minimally coupled theory, we derive
field equations by a first order variational principle using the method of
Lagrange multipliers. We look at static, spherically symmetric solutions that
are asymptotically flat. We discuss the nature of horizons for some candidate
black hole solutions according to various values of the parameters $R_0 $ and
$a_1$.
|
[
{
"created": "Fri, 18 Feb 2011 15:59:01 GMT",
"version": "v1"
}
] |
2011-03-22
|
[
[
"Dereli",
"Tekin",
""
],
[
"Sert",
"Özcan",
""
]
] |
We investigate the non-minimal couplings between the electromagnetic fields and gravity through the natural logarithm of the curvature scalar. After we give the Lagrangian formulation of the non-minimally coupled theory, we derive field equations by a first order variational principle using the method of Lagrange multipliers. We look at static, spherically symmetric solutions that are asymptotically flat. We discuss the nature of horizons for some candidate black hole solutions according to various values of the parameters $R_0 $ and $a_1$.
|
0909.2317
|
Silke Weinfurtner
|
Mauricio Richartz, Silke Weinfurtner, A. J. Penner, and W. G. Unruh
|
Generalised superradiant scattering
|
4 pages; new version: new title no other changes;
|
Phys.Rev.D80:124016,2009
|
10.1103/PhysRevD.80.124016
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We analyse the necessary and sufficient conditions for the occurrence of
superradiance. Starting with a wave equation we examine the possibility of
superradiance in terms of an effective potential and boundary conditions. In
particular, we show that the existence of an ergoregion is not sufficient; an
appropriate boundary condition, e.g. only ingoing group velocity waves at an
event horizon, is also crucial. After applying our scheme to the standard
examples of superradiance, we show that analogue models of gravity without an
event horizon do not necessarily exhibit superradiance. Particularly, we show
that the superradiant phenomenon is absent in purely rotating inviscid fluids
with vorticity. We argue that there should be a catalogue of superradiant
systems that can be found by focusing on the necessary and sufficient
conditions outlined below.
|
[
{
"created": "Sat, 12 Sep 2009 09:27:28 GMT",
"version": "v1"
},
{
"created": "Sat, 19 Sep 2009 08:01:08 GMT",
"version": "v2"
}
] |
2009-12-30
|
[
[
"Richartz",
"Mauricio",
""
],
[
"Weinfurtner",
"Silke",
""
],
[
"Penner",
"A. J.",
""
],
[
"Unruh",
"W. G.",
""
]
] |
We analyse the necessary and sufficient conditions for the occurrence of superradiance. Starting with a wave equation we examine the possibility of superradiance in terms of an effective potential and boundary conditions. In particular, we show that the existence of an ergoregion is not sufficient; an appropriate boundary condition, e.g. only ingoing group velocity waves at an event horizon, is also crucial. After applying our scheme to the standard examples of superradiance, we show that analogue models of gravity without an event horizon do not necessarily exhibit superradiance. Particularly, we show that the superradiant phenomenon is absent in purely rotating inviscid fluids with vorticity. We argue that there should be a catalogue of superradiant systems that can be found by focusing on the necessary and sufficient conditions outlined below.
|
1404.4270
|
Ugur Camci
|
U. Camci
|
Symmetries of geodesic motion in G\"{o}del-type spacetimes
|
21 pages, minor revision, submitted to JCAP
|
JCAP07(2014)002
|
10.1088/1475-7516/2014/07/002
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, we study Noether gauge symmetries of geodesic motion for
geodesic Lagrangian of four classes of metrics of G\"{o}del-type spacetimes for
which we calculated the Noether gauge symmetries for all classes I-IV, and find
the first integrals of corresponding classes to derive a complete
characterization of the geodesic motion. Using the obtained expressions for
$\dot{t}, \dot{r}, \dot{\phi}$ and $\dot{z}$ of each classes I-IV which depends
essentially on two independent parameters $m$ and $w$, we explicitly integrated
the geodesic equations of motion for the corresponding G\"{o}del-type
spacetimes.
|
[
{
"created": "Wed, 16 Apr 2014 14:41:41 GMT",
"version": "v1"
},
{
"created": "Thu, 15 May 2014 15:07:08 GMT",
"version": "v2"
}
] |
2015-06-19
|
[
[
"Camci",
"U.",
""
]
] |
In this paper, we study Noether gauge symmetries of geodesic motion for geodesic Lagrangian of four classes of metrics of G\"{o}del-type spacetimes for which we calculated the Noether gauge symmetries for all classes I-IV, and find the first integrals of corresponding classes to derive a complete characterization of the geodesic motion. Using the obtained expressions for $\dot{t}, \dot{r}, \dot{\phi}$ and $\dot{z}$ of each classes I-IV which depends essentially on two independent parameters $m$ and $w$, we explicitly integrated the geodesic equations of motion for the corresponding G\"{o}del-type spacetimes.
|
1712.01962
|
Seyed Meraj Mousavi Rasouli
|
S. M. M. Rasouli, Paulo Vargas Moniz
|
Modified Saez-Ballester scalar-tensor theory from 5D space-time
|
18 pages, 2 figures
|
Class. Quantum Grav. 35 (2018) 025004
|
10.1088/1361-6382/aa9ad3
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, we bring together the five-dimensional Saez-Ballester~(SB)
scalar-tensor theory [1] and the induced-matter-theory~(IMT) setting [2], to
obtain a modified SB theory (MSBT) in four dimensions. Specifically, by using
an intrinsic dimensional reduction procedure into the SB field equations in
five-dimensions, a MSBT is obtained onto a hypersurface orthogonal to the extra
dimension. This four-dimensional MSBT is shown to bear distinctive new features
in contrast to the usual corresponding SB theory as well as to IMT and the
Modified Brans-Dicke Theory (MBDT)~\cite{RFM14}. It should be emphasized that
the herein appealing solutions can emerge solely from the geometrical
reductional process, from presence also of extra dimension(s) and not from any
ad-hoc matter either in the bulk or on the hypersurface.
Subsequently, we apply the herein MSBT to cosmology and consider an extended
spatially flat FLRW geometry in a five-dimensional vacuum space-time. After
obtaining the exact solutions in the bulk, we proceed to construct, by means of
the MSBT setting, the corresponding dynamic, on the four-dimensional
hypersurface. More precisely, we obtain the (SB) components of the induced
matter, including the induced scalar potential terms. We retrieve two different
classes of solutions. Concerning the first class, we show that the MSBT yields
a barotropic equation of state for the induced perfect fluid. We then
investigate vacuum, dust, radiation, stiff fluid and false vacuum cosmologies
for this scenario and contrast the results with those obtained in the standard
SB theory, IMT and BD theory. Regarding the second class solutions, we show
that the scale factor behaves similar to a de Sitter (DeS) model. However, in
our MSBT setting, this behavior is assisted by non-vanishing induced matter
instead, without any a priori cosmological constant.
|
[
{
"created": "Tue, 5 Dec 2017 23:05:05 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Feb 2018 14:07:52 GMT",
"version": "v2"
}
] |
2018-02-15
|
[
[
"Rasouli",
"S. M. M.",
""
],
[
"Moniz",
"Paulo Vargas",
""
]
] |
In this paper, we bring together the five-dimensional Saez-Ballester~(SB) scalar-tensor theory [1] and the induced-matter-theory~(IMT) setting [2], to obtain a modified SB theory (MSBT) in four dimensions. Specifically, by using an intrinsic dimensional reduction procedure into the SB field equations in five-dimensions, a MSBT is obtained onto a hypersurface orthogonal to the extra dimension. This four-dimensional MSBT is shown to bear distinctive new features in contrast to the usual corresponding SB theory as well as to IMT and the Modified Brans-Dicke Theory (MBDT)~\cite{RFM14}. It should be emphasized that the herein appealing solutions can emerge solely from the geometrical reductional process, from presence also of extra dimension(s) and not from any ad-hoc matter either in the bulk or on the hypersurface. Subsequently, we apply the herein MSBT to cosmology and consider an extended spatially flat FLRW geometry in a five-dimensional vacuum space-time. After obtaining the exact solutions in the bulk, we proceed to construct, by means of the MSBT setting, the corresponding dynamic, on the four-dimensional hypersurface. More precisely, we obtain the (SB) components of the induced matter, including the induced scalar potential terms. We retrieve two different classes of solutions. Concerning the first class, we show that the MSBT yields a barotropic equation of state for the induced perfect fluid. We then investigate vacuum, dust, radiation, stiff fluid and false vacuum cosmologies for this scenario and contrast the results with those obtained in the standard SB theory, IMT and BD theory. Regarding the second class solutions, we show that the scale factor behaves similar to a de Sitter (DeS) model. However, in our MSBT setting, this behavior is assisted by non-vanishing induced matter instead, without any a priori cosmological constant.
|
gr-qc/9807069
|
N. P. Landsman
|
N.P. Landsman
|
Quantization of singular systems and incomplete motions
|
8 pages
| null | null |
KdV-98-14
|
gr-qc
| null |
The need for a mathematically rigorous quantization procedure of singular
spaces and incomplete motions is pointed out in connection with quantum
cosmology. We put our previous suggestion for such a procedure, based on the
theory of induced representations of C*-algebras, in the light of L. Schwartz'
theory of Hilbert subspaces. This turns out to account for the freedom in the
induction procedure, at the same time providing a basis for generalized
eigenfunction expansions pertinent to the needs of quantum cosmology.
Reinforcing our previous proposal for the wave-function of the Universe, we are
now able to add a concrete prescription for its calculation.
|
[
{
"created": "Fri, 24 Jul 1998 13:02:03 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Landsman",
"N. P.",
""
]
] |
The need for a mathematically rigorous quantization procedure of singular spaces and incomplete motions is pointed out in connection with quantum cosmology. We put our previous suggestion for such a procedure, based on the theory of induced representations of C*-algebras, in the light of L. Schwartz' theory of Hilbert subspaces. This turns out to account for the freedom in the induction procedure, at the same time providing a basis for generalized eigenfunction expansions pertinent to the needs of quantum cosmology. Reinforcing our previous proposal for the wave-function of the Universe, we are now able to add a concrete prescription for its calculation.
|
2108.03885
|
Gilberto Medeiros Kremer
|
Gilberto M. Kremer
|
Jeans Instability from post-Newtonian Boltzmann equation
|
To appear in The European Physical Journal C
|
Eur. Phys. J. C (2021) 81:927
|
10.1140/epjc/s10052-021-09728-y
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Jeans instability within the framework of post-Newtonian Boltzmann and
Poisson equations are analyzed. The components of the energy-momentum tensor
are calculated from a post-Newtonian Maxwell-J\"uttner distribution function.
The perturbations of the distribution function and gravitational potentials
from their background states with the representation of the perturbations as
plane waves lead to a dispersion relation with post-Newtonian corrections. The
influence of the post-Newtonian approximation on the Jeans mass is determined
and it was shown that the mass necessary for an overdensity to begin the
gravitational collapse in the post-Newtonian theory is smaller than the one in
the Newtonian theory.
|
[
{
"created": "Mon, 9 Aug 2021 09:03:48 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Oct 2021 09:15:09 GMT",
"version": "v2"
}
] |
2021-10-26
|
[
[
"Kremer",
"Gilberto M.",
""
]
] |
Jeans instability within the framework of post-Newtonian Boltzmann and Poisson equations are analyzed. The components of the energy-momentum tensor are calculated from a post-Newtonian Maxwell-J\"uttner distribution function. The perturbations of the distribution function and gravitational potentials from their background states with the representation of the perturbations as plane waves lead to a dispersion relation with post-Newtonian corrections. The influence of the post-Newtonian approximation on the Jeans mass is determined and it was shown that the mass necessary for an overdensity to begin the gravitational collapse in the post-Newtonian theory is smaller than the one in the Newtonian theory.
|
0902.2270
|
J. Ponce de Leon
|
J. Ponce de Leon
|
Modern cosmologies from empty Kaluza-Klein solutions in 5D
|
Accepted for publication in JHEP
|
JHEP 0903:052,2009
|
10.1088/1126-6708/2009/03/052
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We show that the empty five-dimensional solutions of
Davidson-Sonnenschtein-Vozmediano, {\em Phys. Rev.} {\bf D32} (1985)1330, in
the "old" Kaluza-Klein gravity, under appropriate interpretation can generate
an ample variety of cosmological models in 4D, which include the
higher-dimensional modifications to general relativity predicted by "modern"
versions of noncompactified 5D gravity as, e.g., induced-matter and braneworld
theories. This is the first time that these solutions are investigated in a
systematic way as embeddings for cosmological models in 4D. They provide a
different formulation, which is complementary to the approaches used in current
versions of 5D relativity.
|
[
{
"created": "Fri, 13 Feb 2009 08:39:01 GMT",
"version": "v1"
}
] |
2010-04-28
|
[
[
"de Leon",
"J. Ponce",
""
]
] |
We show that the empty five-dimensional solutions of Davidson-Sonnenschtein-Vozmediano, {\em Phys. Rev.} {\bf D32} (1985)1330, in the "old" Kaluza-Klein gravity, under appropriate interpretation can generate an ample variety of cosmological models in 4D, which include the higher-dimensional modifications to general relativity predicted by "modern" versions of noncompactified 5D gravity as, e.g., induced-matter and braneworld theories. This is the first time that these solutions are investigated in a systematic way as embeddings for cosmological models in 4D. They provide a different formulation, which is complementary to the approaches used in current versions of 5D relativity.
|
1608.01642
|
Michael Seifert
|
Michael D. Seifert
|
Extending the graviton propagator with a Lorentz-violating vector field
|
4 pages. Presented at the Seventh Meeting on CPT and Lorentz
Symmetry, Bloomington, Indiana, June 20-24, 2016
| null | null | null |
gr-qc hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
I discuss progress towards "bootstrapping" a Lorentz-violating gravity
theory: namely, extending a linear Lorentz-violating theory of a rank-2 tensor
to a non-linear theory by coupling this field to its own stress-energy tensor.
|
[
{
"created": "Thu, 4 Aug 2016 18:52:21 GMT",
"version": "v1"
}
] |
2016-08-05
|
[
[
"Seifert",
"Michael D.",
""
]
] |
I discuss progress towards "bootstrapping" a Lorentz-violating gravity theory: namely, extending a linear Lorentz-violating theory of a rank-2 tensor to a non-linear theory by coupling this field to its own stress-energy tensor.
|
0706.4452
|
Louis Crane
|
Louis Crane
|
What is the Mathematical Structure of Quantum Spacetime?
|
25 pages, latex file
| null | null | null |
gr-qc
| null |
We survey indications from different branches of Physics that the fine scale
structure of spacetime is not adequately described by a manifold. Based on the
hints we accumulate, we propose a new structure, which we call a quantum topos.
In the process of constructing a quantum topos for quantum gravity, we propose
a new, operational approach to the problem of the obervables in quantum
gravity, which leads to a new mathematical point of view on the state sum
models.
|
[
{
"created": "Fri, 29 Jun 2007 16:01:03 GMT",
"version": "v1"
}
] |
2007-07-02
|
[
[
"Crane",
"Louis",
""
]
] |
We survey indications from different branches of Physics that the fine scale structure of spacetime is not adequately described by a manifold. Based on the hints we accumulate, we propose a new structure, which we call a quantum topos. In the process of constructing a quantum topos for quantum gravity, we propose a new, operational approach to the problem of the obervables in quantum gravity, which leads to a new mathematical point of view on the state sum models.
|
2302.06206
|
Andre Maeder
|
Andre Maeder
|
MOND as a peculiar case of the SIV theory
|
9 pages, 2 figures
|
MNRAS 520, 1447 (2023)
|
10.1093/mnras/stad078
| null |
gr-qc astro-ph.CO astro-ph.GA
|
http://creativecommons.org/licenses/by/4.0/
|
The scale invariant theory is preserving the fundamental physical properties
of General Relativity, while enlarging the group of invariances subtending
gravitation theory (Dirac1973; Canuto et al.1977). The Scale Invariant Vacuum
(SIV) theory assumes, as gauging condition, that:"The macroscopic empty space
is scale invariant, homogeneous and isotropic". Some basic properties in Weyl's
Integrable Geometry and cotensor calculus are examined in relation with
scalar-tensor theories. Possible scale invariant effects are strongly reduced
by matter density, both at the cosmological and local levels. The weak feld
limit of SIV tends to MOND, when the scale factor is taken as constant, an
approximation valid (<1%) over the last 400 Myr. A better understanding of the
a0-parameter is obtained: it corresponds to the equilibrium point of the
Newtonian and SIV dynamical acceleration. Parameter a0 is not a universal
constant, it depends on the density and age of the Universe. As MOND is doing,
SIV theory avoids the call to dark matter, moreover the cosmological models
predict accelerated expansion.
|
[
{
"created": "Mon, 13 Feb 2023 09:26:46 GMT",
"version": "v1"
}
] |
2023-10-31
|
[
[
"Maeder",
"Andre",
""
]
] |
The scale invariant theory is preserving the fundamental physical properties of General Relativity, while enlarging the group of invariances subtending gravitation theory (Dirac1973; Canuto et al.1977). The Scale Invariant Vacuum (SIV) theory assumes, as gauging condition, that:"The macroscopic empty space is scale invariant, homogeneous and isotropic". Some basic properties in Weyl's Integrable Geometry and cotensor calculus are examined in relation with scalar-tensor theories. Possible scale invariant effects are strongly reduced by matter density, both at the cosmological and local levels. The weak feld limit of SIV tends to MOND, when the scale factor is taken as constant, an approximation valid (<1%) over the last 400 Myr. A better understanding of the a0-parameter is obtained: it corresponds to the equilibrium point of the Newtonian and SIV dynamical acceleration. Parameter a0 is not a universal constant, it depends on the density and age of the Universe. As MOND is doing, SIV theory avoids the call to dark matter, moreover the cosmological models predict accelerated expansion.
|
gr-qc/0107080
|
Kashif Alvi
|
Kashif Alvi (Caltech)
|
Energy and angular momentum flow into a black hole in a binary
|
23 pages; minor changes and additional references in v2
|
Phys.Rev. D64 (2001) 104020
|
10.1103/PhysRevD.64.104020
| null |
gr-qc
| null |
As a black hole in a binary spirals in gradually from large separation,
energy and angular momentum flow not only to infinity but also into or out of
the hole. In addition, the hole's horizon area increases slowly during this
process. In this paper, the changes in the black hole's mass, spin, and horizon
area during inspiral are calculated for a hole in a circular binary with a
companion body of possibly comparable mass. When the binary is composed of
equal-mass black holes that have spins aligned with the orbital angular
momentum and are rapidly rotating (with spins 99.8 percent of their maximal
values), it is found that the fractional increase in the surface area of each
hole's horizon is one percent by the time the binary spirals down to a
separation b of 6M (where M is the binary's total mass), and seven percent down
to b=2M. The flow of energy and angular momentum into the black holes' horizons
changes the number of gravitational-wave cycles in the LIGO band by no more
than a tenth of a cycle by the time the binary reaches b=2M. The results
obtained in this paper are relevant for the detection and analysis of
gravitational waves from binary systems containing a black hole.
|
[
{
"created": "Wed, 25 Jul 2001 01:38:33 GMT",
"version": "v1"
},
{
"created": "Sat, 1 Sep 2001 20:05:18 GMT",
"version": "v2"
}
] |
2009-11-07
|
[
[
"Alvi",
"Kashif",
"",
"Caltech"
]
] |
As a black hole in a binary spirals in gradually from large separation, energy and angular momentum flow not only to infinity but also into or out of the hole. In addition, the hole's horizon area increases slowly during this process. In this paper, the changes in the black hole's mass, spin, and horizon area during inspiral are calculated for a hole in a circular binary with a companion body of possibly comparable mass. When the binary is composed of equal-mass black holes that have spins aligned with the orbital angular momentum and are rapidly rotating (with spins 99.8 percent of their maximal values), it is found that the fractional increase in the surface area of each hole's horizon is one percent by the time the binary spirals down to a separation b of 6M (where M is the binary's total mass), and seven percent down to b=2M. The flow of energy and angular momentum into the black holes' horizons changes the number of gravitational-wave cycles in the LIGO band by no more than a tenth of a cycle by the time the binary reaches b=2M. The results obtained in this paper are relevant for the detection and analysis of gravitational waves from binary systems containing a black hole.
|
1910.03791
|
El\'ias Castellanos Dr.
|
El\'ias Castellanos, Celia Escamilla-Rivera and Jorge Mastache
|
Is a Bose-Einstein Condensate a good candidate for Dark Matter? A test
with Galaxy Rotation Curves
|
21 pages, 17 figures
|
International Journal of Modern Physics D 2020
|
10.1142/S0218271820500637
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We analyze the rotation curves that correspond to a Bose--Einstein Condensate
(BEC) type halo surrounding a Schwarzschild--type black hole to confront
predictions of the model upon observations of galaxy rotation curves. We model
the halo as a Bose--Einstein condensate in terms of a massive scalar field that
satisfies a Klein--Gordon equation with a self--interaction term. We also
assume that the bosonic cloud is not self--gravitating. To model the halo, we
apply a simple form of the Thomas--Fermi approximation that allows us to
extract relevant results with a simple and concise procedure. Using galaxy data
from a subsample of SPARC data base, we find the best fits of the BEC model by
using the Thomas--Fermi approximation and perform a Bayesian statistics
analysis to compare the obtained BEC's scenarios with the Navarro--Frenk--White
(NFW) model as pivot model. We find that in the centre of galaxies we must have
a supermassive compact central object, i.e., supermassive black hole, in the
range of $\log_{10} M/M_\odot = 11.08 \pm 0.43$ which condensate a boson cloud
with average particle mass $M_\Phi = (3.47 \pm 1.43 )\times10^{-23}$ eV and a
self--interaction coupling constant $\log_{10} (\lambda \; [{\rm pc}^{-1}]) =
-91.09 \pm 0.74 $, i.e., the system behaves as a weakly interacting BEC. We
compare the BEC model with NFW concluding that in general the BEC model using
the Thomas--Fermi approximation is strong enough compared with the NFW
fittings. Moreover, we show that BECs still well--fit the galaxy rotation
curves and, more importantly, could lead to an understanding of the dark matter
nature from first principles.
|
[
{
"created": "Wed, 9 Oct 2019 04:52:39 GMT",
"version": "v1"
},
{
"created": "Tue, 12 May 2020 00:02:35 GMT",
"version": "v2"
}
] |
2020-05-27
|
[
[
"Castellanos",
"Elías",
""
],
[
"Escamilla-Rivera",
"Celia",
""
],
[
"Mastache",
"Jorge",
""
]
] |
We analyze the rotation curves that correspond to a Bose--Einstein Condensate (BEC) type halo surrounding a Schwarzschild--type black hole to confront predictions of the model upon observations of galaxy rotation curves. We model the halo as a Bose--Einstein condensate in terms of a massive scalar field that satisfies a Klein--Gordon equation with a self--interaction term. We also assume that the bosonic cloud is not self--gravitating. To model the halo, we apply a simple form of the Thomas--Fermi approximation that allows us to extract relevant results with a simple and concise procedure. Using galaxy data from a subsample of SPARC data base, we find the best fits of the BEC model by using the Thomas--Fermi approximation and perform a Bayesian statistics analysis to compare the obtained BEC's scenarios with the Navarro--Frenk--White (NFW) model as pivot model. We find that in the centre of galaxies we must have a supermassive compact central object, i.e., supermassive black hole, in the range of $\log_{10} M/M_\odot = 11.08 \pm 0.43$ which condensate a boson cloud with average particle mass $M_\Phi = (3.47 \pm 1.43 )\times10^{-23}$ eV and a self--interaction coupling constant $\log_{10} (\lambda \; [{\rm pc}^{-1}]) = -91.09 \pm 0.74 $, i.e., the system behaves as a weakly interacting BEC. We compare the BEC model with NFW concluding that in general the BEC model using the Thomas--Fermi approximation is strong enough compared with the NFW fittings. Moreover, we show that BECs still well--fit the galaxy rotation curves and, more importantly, could lead to an understanding of the dark matter nature from first principles.
|
gr-qc/9707049
|
Jerry Griffiths
|
G A Alekseev and J B Griffiths
|
Gravitational waves with distinct wavefronts
|
14 pages, Plain TeX, no figures. To appear in Classical and Quantum
Gravity
|
Class.Quant.Grav.14:2869-2880,1997
|
10.1088/0264-9381/14/10/013
| null |
gr-qc
| null |
Exact solutions of Einstein's vacuum equations are considered which describe
gravitational waves with distinct wavefronts. A family of such solutions
presented recently in which the wavefronts have various geometries and which
propagate into a number of physically significant backgrounds is here related
to an integral representation which is a generalisation of the Rosen pulse
solution for cylindrical waves. A nondiagonal solution is also constructed
which is a generalisation of the Rosen pulse, being a cylindrical pulse wave
with two states of polarization propagating into a Minkowski background. The
solution is given in a complete and explicit form. A further generalisation to
include electromagnetic waves with a distinct wavefront of the same type is
also discussed.
|
[
{
"created": "Tue, 22 Jul 1997 15:46:25 GMT",
"version": "v1"
}
] |
2008-11-26
|
[
[
"Alekseev",
"G A",
""
],
[
"Griffiths",
"J B",
""
]
] |
Exact solutions of Einstein's vacuum equations are considered which describe gravitational waves with distinct wavefronts. A family of such solutions presented recently in which the wavefronts have various geometries and which propagate into a number of physically significant backgrounds is here related to an integral representation which is a generalisation of the Rosen pulse solution for cylindrical waves. A nondiagonal solution is also constructed which is a generalisation of the Rosen pulse, being a cylindrical pulse wave with two states of polarization propagating into a Minkowski background. The solution is given in a complete and explicit form. A further generalisation to include electromagnetic waves with a distinct wavefront of the same type is also discussed.
|
0712.3721
|
Michael B. Mensky
|
Michael B. Mensky
|
On gravitational-electromagnetic resonance
|
11 pages, LATEX
| null | null | null |
gr-qc
| null |
This is an English translation of the paper M.B.Mensky, in: K.P.Stanyukovich
(ed.), "Problems of Theory of Gravity and Elementary Particles", issue 6,
Moscow, Atomizdat, 1975, p.181-190 (in Russian). This paper elaborates further
the idea (formulated in 1971 by Braginsky and Mensky) of detecting
high-frequency gravitational waves by observing resonance action of a
gravitational wave on the electromagnetic wave in a closed resonator
(waveguide). The phenomenon underlying such a detector was called
gravitational-electromagnetic resonance (GER). In the present paper both closed
(for example circular) resonator or waveguide and long (for example in the
shape of a spiral) waveguide are considered as possible gravitational-wave
detectors. High-frequency gravitational-wave detectors are now again actual
(see A.M.Cruise and R.M.J.Ingley, Class. Quant. Grav. 22, S479, 2005), but the
current literature on this topic does not cover all the issues discussed in the
present paper.
|
[
{
"created": "Fri, 21 Dec 2007 15:35:55 GMT",
"version": "v1"
}
] |
2007-12-24
|
[
[
"Mensky",
"Michael B.",
""
]
] |
This is an English translation of the paper M.B.Mensky, in: K.P.Stanyukovich (ed.), "Problems of Theory of Gravity and Elementary Particles", issue 6, Moscow, Atomizdat, 1975, p.181-190 (in Russian). This paper elaborates further the idea (formulated in 1971 by Braginsky and Mensky) of detecting high-frequency gravitational waves by observing resonance action of a gravitational wave on the electromagnetic wave in a closed resonator (waveguide). The phenomenon underlying such a detector was called gravitational-electromagnetic resonance (GER). In the present paper both closed (for example circular) resonator or waveguide and long (for example in the shape of a spiral) waveguide are considered as possible gravitational-wave detectors. High-frequency gravitational-wave detectors are now again actual (see A.M.Cruise and R.M.J.Ingley, Class. Quant. Grav. 22, S479, 2005), but the current literature on this topic does not cover all the issues discussed in the present paper.
|
2304.14304
|
Vicharit Yingcharoenrat
|
Shinji Mukohyama, Kazufumi Takahashi, Keitaro Tomikawa, Vicharit
Yingcharoenrat
|
Quasinormal Modes from EFT of Black Hole Perturbations with Timelike
Scalar Profile
|
33 pages, 4 figures, 2 tables. Matches JCAP version
| null |
10.1088/1475-7516/2023/07/050
|
YITP-23-45, IPMU23-0007, RUP-23-8
|
gr-qc hep-th
|
http://creativecommons.org/licenses/by/4.0/
|
The Effective Field Theory (EFT) of perturbations on an arbitrary background
geometry with a timelike scalar profile was recently constructed in the context
of scalar-tensor theories. In this paper, we use this EFT to study quasinormal
frequencies of odd-parity perturbations on a static and spherically symmetric
black hole background. Keeping a set of operators that can accommodate
shift-symmetric quadratic higher-order scalar-tensor theories, we demonstrate
the computation for two examples of hairy black holes, of which one is the
stealth Schwarzschild solution and the other is the Hayward metric accompanied
by a non-trivial scalar field. We emphasize that this is the first
phenomenological application of the EFT, opening a new possibility to test
general relativity and modified gravity theories in the strong gravity regime.
|
[
{
"created": "Thu, 27 Apr 2023 16:10:40 GMT",
"version": "v1"
},
{
"created": "Sat, 22 Jul 2023 03:41:36 GMT",
"version": "v2"
}
] |
2023-07-26
|
[
[
"Mukohyama",
"Shinji",
""
],
[
"Takahashi",
"Kazufumi",
""
],
[
"Tomikawa",
"Keitaro",
""
],
[
"Yingcharoenrat",
"Vicharit",
""
]
] |
The Effective Field Theory (EFT) of perturbations on an arbitrary background geometry with a timelike scalar profile was recently constructed in the context of scalar-tensor theories. In this paper, we use this EFT to study quasinormal frequencies of odd-parity perturbations on a static and spherically symmetric black hole background. Keeping a set of operators that can accommodate shift-symmetric quadratic higher-order scalar-tensor theories, we demonstrate the computation for two examples of hairy black holes, of which one is the stealth Schwarzschild solution and the other is the Hayward metric accompanied by a non-trivial scalar field. We emphasize that this is the first phenomenological application of the EFT, opening a new possibility to test general relativity and modified gravity theories in the strong gravity regime.
|
0804.1688
|
Marco Spaans
|
M. Spaans
|
On Particle Mass Changes and GR: Space-time Topology Causes LHC Leakage
|
small update in light of recent LHC results on the Higgs boson
| null | null | null |
gr-qc astro-ph.CO hep-ex hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
It is argued that a change in particle rest mass must involve a multiply
connected space-time topology. The LHC can probe these topological effects
through the particle leakage (~18%) that it experiences in particle mass
changing interactions. With a probability of ~82%, this 4-space leakage causes
a downward shift in the observable Higgs mass, from its physical value of 131.6
GeV to 125.2 GeV.
|
[
{
"created": "Thu, 10 Apr 2008 12:41:19 GMT",
"version": "v1"
},
{
"created": "Tue, 22 Apr 2008 07:44:20 GMT",
"version": "v2"
},
{
"created": "Fri, 27 Jun 2008 09:57:49 GMT",
"version": "v3"
},
{
"created": "Mon, 3 Jun 2013 06:13:54 GMT",
"version": "v4"
}
] |
2013-06-05
|
[
[
"Spaans",
"M.",
""
]
] |
It is argued that a change in particle rest mass must involve a multiply connected space-time topology. The LHC can probe these topological effects through the particle leakage (~18%) that it experiences in particle mass changing interactions. With a probability of ~82%, this 4-space leakage causes a downward shift in the observable Higgs mass, from its physical value of 131.6 GeV to 125.2 GeV.
|
1406.2696
|
Dejan Stojkovic
|
Dejan Stojkovic
|
Vanishing dimensions: Review
|
Invited review for MPLA, based on the following publications:
Phys.Rev.Lett. 106 (2011) 101101, Phys.Rev.Lett. 107 (2011) 169002, Phys.Rev.
D83 (2011) 114046, Mod.Phys.Lett. A27 (2012) 1250021, arXiv:1405.3297,
arXiv:1304.6444
| null | null | null |
gr-qc hep-ph hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We review a growing theoretical motivation and evidence that the number of
dimensions actually reduces at high energies. This reduction can happen near
the Planck scale, or much before, the dimensions that are reduced can be
effective, spectral, topological or the usual dimensions, but many things
points toward the fact that the high energy theories appear to propagate in a
lower dimensional space, rather than a higher dimensional one. We will
concentrate on a particular scenario of "vanishing" or "evolving dimensions"
where the dimensions open up as we increase the length scale that we are
probing, but will also mention related models that point to the same direction,
i.e. the causal dynamical triangulation, asymptotic safety, as well as evidence
coming from a non-commutative quantum theories, the Wheeler-DeWitt equation and
phenomenon of "asymptotic silence". It is intriguing that experimental evidence
for the high energy dimensional reduction may already exists - a statistically
significant planar alignment of events with energies higher than TeV has been
observed in high altitude cosmic ray experiments. A convincing evidence for
dimensional reduction may be found in future in collider experiments and
gravity waves observatories.
|
[
{
"created": "Tue, 10 Jun 2014 20:00:17 GMT",
"version": "v1"
}
] |
2014-06-18
|
[
[
"Stojkovic",
"Dejan",
""
]
] |
We review a growing theoretical motivation and evidence that the number of dimensions actually reduces at high energies. This reduction can happen near the Planck scale, or much before, the dimensions that are reduced can be effective, spectral, topological or the usual dimensions, but many things points toward the fact that the high energy theories appear to propagate in a lower dimensional space, rather than a higher dimensional one. We will concentrate on a particular scenario of "vanishing" or "evolving dimensions" where the dimensions open up as we increase the length scale that we are probing, but will also mention related models that point to the same direction, i.e. the causal dynamical triangulation, asymptotic safety, as well as evidence coming from a non-commutative quantum theories, the Wheeler-DeWitt equation and phenomenon of "asymptotic silence". It is intriguing that experimental evidence for the high energy dimensional reduction may already exists - a statistically significant planar alignment of events with energies higher than TeV has been observed in high altitude cosmic ray experiments. A convincing evidence for dimensional reduction may be found in future in collider experiments and gravity waves observatories.
|
1901.04303
|
Ujjal Debnath
|
Ujjal Debnath
|
Charge Gravastars in $f(T)$ Modified Gravity
|
8 pages, Comments are welcome
| null |
10.1140/epjc/s10052-019-7013-z
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In the present work, we have discussed the four dimensional spherically
symmetric steller system in the framework of modified $f(T)$ gravity theory
with electro-magnetic field. The field equations have been written for two
cases, either $T'=0$ or $f_{TT}=0$. Next we have discussed the charged
gravastar model which has three regions: interior region, shell region and
exterior region. In the interior region, we have found the solutions of all
physical quantities like density, pressure, electro-magnetic field and also the
metric coefficients for both the cases. For $T'=0$, gravastar cannot form but
it forms only for the case $f_{TT}=0$. In the exterior region, we have obtained
the exterior solution for vacuum model. In the shell region, we have assumed
that the interior and exterior regions join together at a place, so the
intermediate region must be thin shell with the approximation $h\ll 1$. Under
this approximation, we have found the analytical solutions. The proper length
of the thin shell, entropy and energy content inside the thin shell have been
found and they are directly proportional to the proper thickness of the shell
$\epsilon$ under the approximation ($\epsilon\ll 1$). According to the
Darmois-Israel formalism, we have studied the matching between the surfaces of
interior and exterior regions of the gravastar. The energy density, pressure,
equation of state parameter on the surface and mass of the thin shell have been
obtained.
|
[
{
"created": "Thu, 10 Jan 2019 04:33:38 GMT",
"version": "v1"
}
] |
2019-07-24
|
[
[
"Debnath",
"Ujjal",
""
]
] |
In the present work, we have discussed the four dimensional spherically symmetric steller system in the framework of modified $f(T)$ gravity theory with electro-magnetic field. The field equations have been written for two cases, either $T'=0$ or $f_{TT}=0$. Next we have discussed the charged gravastar model which has three regions: interior region, shell region and exterior region. In the interior region, we have found the solutions of all physical quantities like density, pressure, electro-magnetic field and also the metric coefficients for both the cases. For $T'=0$, gravastar cannot form but it forms only for the case $f_{TT}=0$. In the exterior region, we have obtained the exterior solution for vacuum model. In the shell region, we have assumed that the interior and exterior regions join together at a place, so the intermediate region must be thin shell with the approximation $h\ll 1$. Under this approximation, we have found the analytical solutions. The proper length of the thin shell, entropy and energy content inside the thin shell have been found and they are directly proportional to the proper thickness of the shell $\epsilon$ under the approximation ($\epsilon\ll 1$). According to the Darmois-Israel formalism, we have studied the matching between the surfaces of interior and exterior regions of the gravastar. The energy density, pressure, equation of state parameter on the surface and mass of the thin shell have been obtained.
|
gr-qc/0112018
|
Patrick J. Sutton
|
Patrick J. Sutton and Lee Samuel Finn
|
Bounding the graviton mass with binary pulsar observations
|
9 pages, 1 figure. Presented at Fourth Edoardo Amaldi Conference on
Gravitational Waves, Perth, 2001
|
Class.Quant.Grav. 19 (2002) 1355-1360
|
10.1088/0264-9381/19/7/318
| null |
gr-qc
| null |
By comparing the observed orbital decay of the binary pulsars PSRB1913+16 and
PSRB1534+12 to that predicted by general relativity due to gravitational-wave
emission, we are able to bound the mass of the graviton to be less than
$7.6\times10^{-20} \text{eV}/c^2$ at 90% confidence. This is the first such
bound to be derived from dynamic gravitational fields. It is approximately two
orders of magnitude weaker than the static-field bound from solar system
observations, and will improve with further observations.
|
[
{
"created": "Mon, 10 Dec 2001 17:48:46 GMT",
"version": "v1"
}
] |
2009-11-07
|
[
[
"Sutton",
"Patrick J.",
""
],
[
"Finn",
"Lee Samuel",
""
]
] |
By comparing the observed orbital decay of the binary pulsars PSRB1913+16 and PSRB1534+12 to that predicted by general relativity due to gravitational-wave emission, we are able to bound the mass of the graviton to be less than $7.6\times10^{-20} \text{eV}/c^2$ at 90% confidence. This is the first such bound to be derived from dynamic gravitational fields. It is approximately two orders of magnitude weaker than the static-field bound from solar system observations, and will improve with further observations.
|
1406.3237
|
Maria Principe
|
Maria Principe
|
Minimum Noise Optical Coatings for Interferometric Detectors of
Gravitational Waves
|
6 pages, 9 figures, 50 references, Proc of the IEEE International
Workshop on Metrology for Aerospace 2014
| null |
10.1364/OE.23.010938
| null |
gr-qc astro-ph.IM physics.optics
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Coating Brownian noise is the dominant noise term, in a frequency band from a
few tens to a few hundreds Hz, for all Earth-bound detectors of gravitational
waves. Minimizing such noise is mandatory to increase the visibility distance
of these instruments, and eventually reach their quantum limit. Several
strategies are possible to achieve this goal. Layer thickness optimization is
the simplest option, yielding a sensible noise reduction with limited
technological challenges. Experimental results confirm the accuracy of the
underlying theory, and the robustness of the design.
|
[
{
"created": "Thu, 12 Jun 2014 13:34:08 GMT",
"version": "v1"
}
] |
2023-07-19
|
[
[
"Principe",
"Maria",
""
]
] |
Coating Brownian noise is the dominant noise term, in a frequency band from a few tens to a few hundreds Hz, for all Earth-bound detectors of gravitational waves. Minimizing such noise is mandatory to increase the visibility distance of these instruments, and eventually reach their quantum limit. Several strategies are possible to achieve this goal. Layer thickness optimization is the simplest option, yielding a sensible noise reduction with limited technological challenges. Experimental results confirm the accuracy of the underlying theory, and the robustness of the design.
|
1310.0030
|
Emil Mottola
|
Paul R. Anderson (Wake Forest Univ.) and Emil Mottola (Los Alamos
National Laboratory)
|
On the Instability of Global de Sitter Space to Particle Creation
|
60 pages, 15 figures
|
Phys. Rev. D 89, 104038 (2014)
|
10.1103/PhysRevD.89.104038
|
LA-UR-13-26338
|
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We show that global de Sitter space is unstable to particle creation, even
for a massive free field theory with no self-interactions. The O(4,1) de Sitter
invariant state is a definite phase coherent superposition of particle and
anti-particle solutions in both the asymptotic past and future, and therefore
is not a true vacuum state. In the closely related case of particle creation by
a constant, uniform electric field, a time symmetric state analogous to the de
Sitter invariant one is constructed, which is also not a stable vacuum state.
We provide the general framework necessary to describe the particle creation
process, the mean particle number, and dynamical quantities such as the
energy-momentum tensor and current of the created particles in both the de
Sitter and electric field backgrounds in real time, establishing the connection
to kinetic theory. We compute the energy-momentum tensor for adiabatic vacuum
states in de Sitter space initialized at early times in global S^3 sections,
and show that particle creation in the contracting phase results in
exponentially large energy densities at later times, necessitating an inclusion
of their backreaction effects, and leading to large deviation of the spacetime
from global de Sitter space before the expanding phase can begin.
|
[
{
"created": "Mon, 30 Sep 2013 20:03:39 GMT",
"version": "v1"
}
] |
2014-05-28
|
[
[
"Anderson",
"Paul R.",
"",
"Wake Forest Univ."
],
[
"Mottola",
"Emil",
"",
"Los Alamos\n National Laboratory"
]
] |
We show that global de Sitter space is unstable to particle creation, even for a massive free field theory with no self-interactions. The O(4,1) de Sitter invariant state is a definite phase coherent superposition of particle and anti-particle solutions in both the asymptotic past and future, and therefore is not a true vacuum state. In the closely related case of particle creation by a constant, uniform electric field, a time symmetric state analogous to the de Sitter invariant one is constructed, which is also not a stable vacuum state. We provide the general framework necessary to describe the particle creation process, the mean particle number, and dynamical quantities such as the energy-momentum tensor and current of the created particles in both the de Sitter and electric field backgrounds in real time, establishing the connection to kinetic theory. We compute the energy-momentum tensor for adiabatic vacuum states in de Sitter space initialized at early times in global S^3 sections, and show that particle creation in the contracting phase results in exponentially large energy densities at later times, necessitating an inclusion of their backreaction effects, and leading to large deviation of the spacetime from global de Sitter space before the expanding phase can begin.
|
0706.4301
|
Keith Thorne
|
K. A. Thorne (for the LIGO Scientific Collaboration)
|
Searching for Gravitational-Wave Bursts with LIGO
|
9 pages, 3 figures, for the Proceedings of the Recontres de Moriond:
Gravitational Waves and Experimental Gravity (March 11-18, 2007)
| null | null |
LIGO-P070062-03
|
gr-qc
| null |
We present recent results from searches by the LIGO Science Collaboration for
bursts of gravitational-wave radiation, as well as the status of other ongoing
searches. These include directed searches for bursts associated with observed
sources (gamma-ray bursts, soft gamma repeaters) and untriggered searches for
bursts from unknown sources. We also present the status of some newer
investigations, such as coherent network methods. We show methods for
interpreting our search results in terms of astrophysical source distributions
that improve their accessibility to the wider community.
|
[
{
"created": "Thu, 28 Jun 2007 19:13:29 GMT",
"version": "v1"
}
] |
2007-06-29
|
[
[
"Thorne",
"K. A.",
"",
"for the LIGO Scientific Collaboration"
]
] |
We present recent results from searches by the LIGO Science Collaboration for bursts of gravitational-wave radiation, as well as the status of other ongoing searches. These include directed searches for bursts associated with observed sources (gamma-ray bursts, soft gamma repeaters) and untriggered searches for bursts from unknown sources. We also present the status of some newer investigations, such as coherent network methods. We show methods for interpreting our search results in terms of astrophysical source distributions that improve their accessibility to the wider community.
|
gr-qc/9504036
|
John Baez
|
John C. Baez
|
Spin Networks in Nonperturbative Quantum Gravity
|
41 pages in LaTeX
|
in The Interface of Knots and Physics, ed. Louis Kauffman, A.M.S.,
Providence, 1996, pp. 167-203
| null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A spin network is a generalization of a knot or link: a graph embedded in
space, with edges labelled by representations of a Lie group, and vertices
labelled by intertwining operators. Such objects play an important role in
3-dimensional topological quantum field theory, functional integration on the
space A/G of connections modulo gauge transformations, and the loop
representation of quantum gravity. Here, after an introduction to the basic
ideas of nonperturbative canonical quantum gravity, we review a rigorous
approach to functional integration on A/G in which L^2(A/G) is spanned by
states labelled by spin networks. Then we explain the `new variables' for
general relativity in 4-dimensional spacetime and describe how canonical
quantization of gravity in this formalism leads to interesting applications of
these spin network states.
|
[
{
"created": "Fri, 21 Apr 1995 19:03:28 GMT",
"version": "v1"
},
{
"created": "Sat, 24 Jul 2010 05:07:13 GMT",
"version": "v2"
}
] |
2010-07-27
|
[
[
"Baez",
"John C.",
""
]
] |
A spin network is a generalization of a knot or link: a graph embedded in space, with edges labelled by representations of a Lie group, and vertices labelled by intertwining operators. Such objects play an important role in 3-dimensional topological quantum field theory, functional integration on the space A/G of connections modulo gauge transformations, and the loop representation of quantum gravity. Here, after an introduction to the basic ideas of nonperturbative canonical quantum gravity, we review a rigorous approach to functional integration on A/G in which L^2(A/G) is spanned by states labelled by spin networks. Then we explain the `new variables' for general relativity in 4-dimensional spacetime and describe how canonical quantization of gravity in this formalism leads to interesting applications of these spin network states.
|
gr-qc/0308090
|
Peter Fritschel
|
Peter Fritschel
|
Second generation instruments for the Laser Interferometer Gravitational
Wave Observatory (LIGO)
|
Proceedings of the SPIE conference on Astronomical Telescopes and
Instrumentations, 22-28 Aug 2002, Waikoloa, HI, USA
|
Proceedings of SPIE Vol. 4856 "Gravitational Wave Detection",
edited by Mike Cruise, Peter Saulson, (SPIE, Bellingham, WA, 2003) pp 282-291
|
10.1117/12.459090
|
LIGO-P020016-00-R
|
gr-qc
| null |
The interferometers being planned for second generation LIGO promise and
order of magnitude increase in broadband strain sensitivity--with the
corresponding cubic increase in detection volume--and an extension of the
observation band to lower frequencies. In addition, one of the interferometers
may be designed for narrowband performance, giving further improved sensitivity
over roughly an octave band above a few hundred Hertz. This article discusses
the physics and technology of these new interferometer designs, and presents
their projected sensitivity spectra.
|
[
{
"created": "Thu, 28 Aug 2003 14:44:51 GMT",
"version": "v1"
}
] |
2009-11-10
|
[
[
"Fritschel",
"Peter",
""
]
] |
The interferometers being planned for second generation LIGO promise and order of magnitude increase in broadband strain sensitivity--with the corresponding cubic increase in detection volume--and an extension of the observation band to lower frequencies. In addition, one of the interferometers may be designed for narrowband performance, giving further improved sensitivity over roughly an octave band above a few hundred Hertz. This article discusses the physics and technology of these new interferometer designs, and presents their projected sensitivity spectra.
|
2210.16439
|
Nelson Yokomizo
|
Bekir Baytas, Nelson Yokomizo
|
Cosmological states in loop quantum gravity on homogeneous graphs
|
60 pages, 11 figures
| null |
10.1103/PhysRevD.107.066009
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We introduce a class of states characterized by proposed conditions of
homogeneity and isotropy in loop quantum gravity and construct concrete
examples given by Bell-network states on a special class of homogeneous graphs.
Such states provide new representations of cosmological spaces that can be
explored for the formulation of cosmological models in the context of loop
quantum gravity. We show that their local geometry is described in an
automorphism-invariant manner by one-node observables analogous to the one-body
observables used in many-body quantum mechanics, and compute the density matrix
representing the restriction of global states to the algebra of one-node
observables. The von Neumann entropy of this density matrix provides a notion
of entanglement entropy of a local region which respects
automorphism-invariance and can be applied to states involving superpositions
of distinct graphs.
|
[
{
"created": "Fri, 28 Oct 2022 23:51:22 GMT",
"version": "v1"
},
{
"created": "Thu, 29 Dec 2022 13:28:33 GMT",
"version": "v2"
}
] |
2023-03-29
|
[
[
"Baytas",
"Bekir",
""
],
[
"Yokomizo",
"Nelson",
""
]
] |
We introduce a class of states characterized by proposed conditions of homogeneity and isotropy in loop quantum gravity and construct concrete examples given by Bell-network states on a special class of homogeneous graphs. Such states provide new representations of cosmological spaces that can be explored for the formulation of cosmological models in the context of loop quantum gravity. We show that their local geometry is described in an automorphism-invariant manner by one-node observables analogous to the one-body observables used in many-body quantum mechanics, and compute the density matrix representing the restriction of global states to the algebra of one-node observables. The von Neumann entropy of this density matrix provides a notion of entanglement entropy of a local region which respects automorphism-invariance and can be applied to states involving superpositions of distinct graphs.
|
0707.0146
|
Matt Visser
|
Petarpa Boonserm (Victoria University of Wellington) and Matt Visser
(Victoria University of Wellington)
|
Buchdahl-like transformations for perfect fluid spheres
|
23 pages
|
Int.J.Mod.Phys.D17:135-163,2008
|
10.1142/S0218271808011912
| null |
gr-qc
| null |
In two previous articles [Phys. Rev. D71 (2005) 124307 (gr-qc/0503007), and
gr-qc/0607001] we have discussed several "algorithmic" techniques that permit
one (in a purely mechanical way) to generate large classes of general
relativistic static perfect fluid spheres. Working in Schwarzschild curvature
coordinates, we used these algorithmic ideas to prove several
"solution-generating theorems" of varying levels of complexity. In the present
article we consider the situation in other coordinate systems: In particular,
in general diagonal coordinates we shall generalize our previous theorems, in
isotropic coordinates we shall encounter a variant of the so-called "Buchdahl
transformation", while in other coordinate systems (such as Gaussian polar
coordinates, Synge isothermal coordinates, and Buchdahl coordinates) we shall
find a number of more complex "Buchdahl-like transformations" and
"solution-generating theorems" that may be used to investigate and classify the
general relativistic static perfect fluid sphere. Finally by returning to
general diagonal coordinates and making a suitable ansatz for the functional
form of the metric components we place the Buchdahl transformation in its most
general possible setting.
|
[
{
"created": "Mon, 2 Jul 2007 05:54:26 GMT",
"version": "v1"
}
] |
2008-11-26
|
[
[
"Boonserm",
"Petarpa",
"",
"Victoria University of Wellington"
],
[
"Visser",
"Matt",
"",
"Victoria University of Wellington"
]
] |
In two previous articles [Phys. Rev. D71 (2005) 124307 (gr-qc/0503007), and gr-qc/0607001] we have discussed several "algorithmic" techniques that permit one (in a purely mechanical way) to generate large classes of general relativistic static perfect fluid spheres. Working in Schwarzschild curvature coordinates, we used these algorithmic ideas to prove several "solution-generating theorems" of varying levels of complexity. In the present article we consider the situation in other coordinate systems: In particular, in general diagonal coordinates we shall generalize our previous theorems, in isotropic coordinates we shall encounter a variant of the so-called "Buchdahl transformation", while in other coordinate systems (such as Gaussian polar coordinates, Synge isothermal coordinates, and Buchdahl coordinates) we shall find a number of more complex "Buchdahl-like transformations" and "solution-generating theorems" that may be used to investigate and classify the general relativistic static perfect fluid sphere. Finally by returning to general diagonal coordinates and making a suitable ansatz for the functional form of the metric components we place the Buchdahl transformation in its most general possible setting.
|
1603.07932
|
Pratik Tarafdar
|
Pratik Tarafdar and Tapas Kumar Das
|
Influence of matter geometry on shocked flows-I: Accretion in the
Schwarzschild metric
|
42 pages, 9 figures. Substantial modification in various sections.
Some sections have been rewritten or rephrased
|
New Astronomy, 62, 1-14 (2018)
|
10.1016/j.newast.2017.12.007
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
This work presents a comprehensive and extensive study to illustrate how the
geometrical configurations of low angular momentum axially symmetric general
relativistic matter flow in Schwarzschild metric may influence the formation of
energy preserving shocks for adiabatic/polytropic accretion as well as of
temperature preserving dissipative shocks for for the isothermal accretion onto
non-rotating astrophysical black holes. The dynamical and thermodynamic states
of post shock polytropic and isothermal flow have been studied extensively for
three possible matter geometries, and it has been thoroughly discussed about
how such states depend on the flow structure, even when the self gravity and
the back reaction on the metric are not taken into account. Main purpose of
this paper is thus to mathematically demonstrate that for non-self gravitating
accretion, various matter geometry, in addition to the corresponding space-time
geometry, controls the shock induced phenomena as observed within the black
hole accretion discs. This work is expected to reveal how the shock generated
phenomena (emergence of the outflows/flare or the behaviour of QPO of the
associated light curves) observed at the close proximity of the horizon depends
on the physical environment of the source harbouring a supermassive black hole.
|
[
{
"created": "Fri, 25 Mar 2016 15:22:00 GMT",
"version": "v1"
},
{
"created": "Sat, 24 Sep 2016 10:14:18 GMT",
"version": "v2"
},
{
"created": "Sun, 23 Jul 2017 15:11:26 GMT",
"version": "v3"
}
] |
2021-02-08
|
[
[
"Tarafdar",
"Pratik",
""
],
[
"Das",
"Tapas Kumar",
""
]
] |
This work presents a comprehensive and extensive study to illustrate how the geometrical configurations of low angular momentum axially symmetric general relativistic matter flow in Schwarzschild metric may influence the formation of energy preserving shocks for adiabatic/polytropic accretion as well as of temperature preserving dissipative shocks for for the isothermal accretion onto non-rotating astrophysical black holes. The dynamical and thermodynamic states of post shock polytropic and isothermal flow have been studied extensively for three possible matter geometries, and it has been thoroughly discussed about how such states depend on the flow structure, even when the self gravity and the back reaction on the metric are not taken into account. Main purpose of this paper is thus to mathematically demonstrate that for non-self gravitating accretion, various matter geometry, in addition to the corresponding space-time geometry, controls the shock induced phenomena as observed within the black hole accretion discs. This work is expected to reveal how the shock generated phenomena (emergence of the outflows/flare or the behaviour of QPO of the associated light curves) observed at the close proximity of the horizon depends on the physical environment of the source harbouring a supermassive black hole.
|
1703.10320
|
Jie-Xiong Mo
|
Jie-Xiong Mo, Gu-Qiang Li
|
Ratio of critical quantities related to Hawking temperature-entanglement
entropy criticality
|
Comments welcome. 11 pages, 3 figures
| null |
10.1016/j.nuclphysb.2017.08.001
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We revisit the Hawking temperature$-$entanglement entropy criticality of the
$d$-dimensional charged AdS black hole with our attention concentrated on the
ratio $\frac{T_c \delta S_c}{Q_c}$. Comparing the results of this paper with
those of the ratio $\frac{T_c S_c}{Q_c}$, one can find both the similarities
and differences. These two ratios are independent of the characteristic length
scale $l$ and dependent on the dimension $d$. These similarities further
enhance the relation between the entanglement entropy and the
Bekenstein-Hawking entropy. However, the ratio $\frac{T_c \delta S_c}{Q_c}$
also relies on the size of the spherical entangling region. Moreover, these two
ratios take different values even under the same choices of parameters. The
differences between these two ratios can be attributed to the peculiar property
of the entanglement entropy since the research in this paper is far from the
regime where the behavior of the entanglement entropy is dominated by the
thermal entropy.
|
[
{
"created": "Thu, 30 Mar 2017 05:32:07 GMT",
"version": "v1"
}
] |
2018-03-14
|
[
[
"Mo",
"Jie-Xiong",
""
],
[
"Li",
"Gu-Qiang",
""
]
] |
We revisit the Hawking temperature$-$entanglement entropy criticality of the $d$-dimensional charged AdS black hole with our attention concentrated on the ratio $\frac{T_c \delta S_c}{Q_c}$. Comparing the results of this paper with those of the ratio $\frac{T_c S_c}{Q_c}$, one can find both the similarities and differences. These two ratios are independent of the characteristic length scale $l$ and dependent on the dimension $d$. These similarities further enhance the relation between the entanglement entropy and the Bekenstein-Hawking entropy. However, the ratio $\frac{T_c \delta S_c}{Q_c}$ also relies on the size of the spherical entangling region. Moreover, these two ratios take different values even under the same choices of parameters. The differences between these two ratios can be attributed to the peculiar property of the entanglement entropy since the research in this paper is far from the regime where the behavior of the entanglement entropy is dominated by the thermal entropy.
|
0901.3727
|
Alexis Larranaga
|
Alexis Larranaga, Hector J. Hortua
|
Temperature for the (2+1)-dimensional Black Hole with Non Linear
Electrodynamics from the Generalized Uncertainty Principle
|
7 pages
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, we study the thermodynamical properties of the (2+1)
dimensional black hole with a non-linear electrodynamics and with a negative
cosmological constant, using the Generalized Uncertainty Principle (GUP). This
approach shows that there is a minimum mass or remnant for the black hole,
corresponding to the minimum radius of the event horizon that has a size of the
order of the Planck scale. We also show that the heat capacity for this black
hole is always positive.
|
[
{
"created": "Fri, 23 Jan 2009 17:06:27 GMT",
"version": "v1"
}
] |
2010-12-10
|
[
[
"Larranaga",
"Alexis",
""
],
[
"Hortua",
"Hector J.",
""
]
] |
In this paper, we study the thermodynamical properties of the (2+1) dimensional black hole with a non-linear electrodynamics and with a negative cosmological constant, using the Generalized Uncertainty Principle (GUP). This approach shows that there is a minimum mass or remnant for the black hole, corresponding to the minimum radius of the event horizon that has a size of the order of the Planck scale. We also show that the heat capacity for this black hole is always positive.
|
0801.4531
|
Gil de Oliveira-Neto
|
G. Oliveira-Neto and G. F. Sousa
|
Qualitative and quantitative features of orbits of massive particles and
photons moving in Wyman geometry
|
20 pages, 8 ps figures, IOPLaTeX
|
Braz.J.Phys.38:573-580,2008
|
10.1590/S0103-97332008000500008
| null |
gr-qc
| null |
The Wyman's solution depends on two parameters, the mass $M$ and the scalar
charge $\sigma$. If one fixes $M$ to a positive value, say $M_0$, and let
$\sigma^2$ take values along the real line it describes three different types
of spacetimes. For $\sigma^2 >0$ the spacetimes are naked singularities, for
$\sigma^2 = 0$ one has the Schwarzschild black hole of mass $M_0$ and finally
for $-M_0^2 \leq \sigma^2 < 0$ one has wormhole spacetimes. In the present
work, we shall study qualitative and quantitative features of orbits of massive
particles and photons moving in the naked singularity and wormhole spacetimes
of the Wyman solution. These orbits are the timelike geodesics for massive
particles and null geodesics for photons. Combining the four geodesic equations
with an additional equation derived from the line element, we obtain an
effective potential for the massive particles and a different effective
potential for the photons. We investigate all possible types of orbits, for
massive particles and photons, by studying the appropriate effective potential.
We notice that for certain values of $\sigma^2 >0$, there is an infinity
potential wall that prevents both massive particles and photons ever to reach
the naked singularity. We notice, also, that for certain values of $-M_0^2 \leq
\sigma^2 < 0$, the potential is finite everywhere, which allows massive
particles and photons moving from one wormhole asymptotically flat region to
the other. We also compute the radial timelike and null geodesics for massive
particles and photons, respectively, moving in the naked singularities and
wormholes spacetimes.
|
[
{
"created": "Tue, 29 Jan 2008 16:36:11 GMT",
"version": "v1"
}
] |
2011-08-31
|
[
[
"Oliveira-Neto",
"G.",
""
],
[
"Sousa",
"G. F.",
""
]
] |
The Wyman's solution depends on two parameters, the mass $M$ and the scalar charge $\sigma$. If one fixes $M$ to a positive value, say $M_0$, and let $\sigma^2$ take values along the real line it describes three different types of spacetimes. For $\sigma^2 >0$ the spacetimes are naked singularities, for $\sigma^2 = 0$ one has the Schwarzschild black hole of mass $M_0$ and finally for $-M_0^2 \leq \sigma^2 < 0$ one has wormhole spacetimes. In the present work, we shall study qualitative and quantitative features of orbits of massive particles and photons moving in the naked singularity and wormhole spacetimes of the Wyman solution. These orbits are the timelike geodesics for massive particles and null geodesics for photons. Combining the four geodesic equations with an additional equation derived from the line element, we obtain an effective potential for the massive particles and a different effective potential for the photons. We investigate all possible types of orbits, for massive particles and photons, by studying the appropriate effective potential. We notice that for certain values of $\sigma^2 >0$, there is an infinity potential wall that prevents both massive particles and photons ever to reach the naked singularity. We notice, also, that for certain values of $-M_0^2 \leq \sigma^2 < 0$, the potential is finite everywhere, which allows massive particles and photons moving from one wormhole asymptotically flat region to the other. We also compute the radial timelike and null geodesics for massive particles and photons, respectively, moving in the naked singularities and wormholes spacetimes.
|
gr-qc/9708027
| null |
O.B. Zaslavskii
|
Entropy of Quantum Fields for Nonextreme Black Holes in the Extreme
Limit
|
11 pages, ReVTeX, no figures. New references added, discussion
expanded, presentation and English improved. Accepted for publication in
Phys. Rev. D
|
Phys.Rev. D57 (1998) 6265-6268
|
10.1103/PhysRevD.57.6265
| null |
gr-qc hep-th
| null |
Nonextreme black hole in a cavity within the framework of the canonical or
grand canonical ensemble can approach the extreme limit with a finite
temperature measured on a boundary located at a finite proper distance from the
horizon. In spite of this finite temperature, it is shown that the one-loop
contribution $S_{q\text{ }}$of quantum fields to the thermodynamic entropy due
to equilibrium Hawking radiation vanishes in the limit under consideration. The
same is true for the finite temperature version of the Bertotti-Robinson
spacetime into which a classical Reissner-Nordstr\"{o}m black hole turns in the
extreme limit. The result $S_{q}=0$ is attributed to the nature of a horizon
for the Bertotti-Robinson spacetime.
|
[
{
"created": "Wed, 6 Aug 1997 12:48:22 GMT",
"version": "v1"
},
{
"created": "Fri, 3 Oct 1997 15:03:27 GMT",
"version": "v2"
},
{
"created": "Fri, 27 Feb 1998 13:47:53 GMT",
"version": "v3"
}
] |
2009-10-30
|
[
[
"Zaslavskii",
"O. B.",
""
]
] |
Nonextreme black hole in a cavity within the framework of the canonical or grand canonical ensemble can approach the extreme limit with a finite temperature measured on a boundary located at a finite proper distance from the horizon. In spite of this finite temperature, it is shown that the one-loop contribution $S_{q\text{ }}$of quantum fields to the thermodynamic entropy due to equilibrium Hawking radiation vanishes in the limit under consideration. The same is true for the finite temperature version of the Bertotti-Robinson spacetime into which a classical Reissner-Nordstr\"{o}m black hole turns in the extreme limit. The result $S_{q}=0$ is attributed to the nature of a horizon for the Bertotti-Robinson spacetime.
|
1110.2386
|
Plyatsko Roman
|
Roman Plyatsko
|
Can Mathisson-Papapetrou equations give clue to some problems in
astrophysics?
|
3 page
| null | null | null |
gr-qc astro-ph.HE hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
First, we stress that for correct description of highly relativistic fermions
in a gravitational field it is necessary to have an equation which in the
limiting transition to the classical (non-quantum) case corresponds to the
exact Mathisson-Papapetrou equations. According to these equations the spin in
general relativity is Fermi-transported, and the parallel transport of spin is
realized only in some approximation. The traditional general-relativistic Dirac
equation (1929) is based on the parallel transported spinors and does not
ensure the correspondent transition. Second, because in the range of very high
velocity (close to the speed of light) of a spinning particle relative to the
Schwarzschild or Kerr sources the Mathisson-Papapetrou equations have the
solutions which reveal that the spin-gravity interaction acts as a strong
antigravity force, we suppose that this fact can be useful for explanation some
astrophysical phenomena. Some association with the OPERA results is possible.
|
[
{
"created": "Tue, 11 Oct 2011 14:23:46 GMT",
"version": "v1"
}
] |
2011-10-12
|
[
[
"Plyatsko",
"Roman",
""
]
] |
First, we stress that for correct description of highly relativistic fermions in a gravitational field it is necessary to have an equation which in the limiting transition to the classical (non-quantum) case corresponds to the exact Mathisson-Papapetrou equations. According to these equations the spin in general relativity is Fermi-transported, and the parallel transport of spin is realized only in some approximation. The traditional general-relativistic Dirac equation (1929) is based on the parallel transported spinors and does not ensure the correspondent transition. Second, because in the range of very high velocity (close to the speed of light) of a spinning particle relative to the Schwarzschild or Kerr sources the Mathisson-Papapetrou equations have the solutions which reveal that the spin-gravity interaction acts as a strong antigravity force, we suppose that this fact can be useful for explanation some astrophysical phenomena. Some association with the OPERA results is possible.
|
2004.03226
|
Yuri Pavlov
|
A. A. Grib, Yu. V. Pavlov
|
Fifty years of the calculation of the density of particles created in
the early Friedmann Universe
|
9 pages, 2 figures
|
Int. J. Mod. Phys. A 35 (2020) 2040034
|
10.1142/S0217751X20400345
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The problem of particle creation in cosmology concerning whether the results
for the number of particles are infinite or finite is discussed for scalar and
spinor particles in Friedmann expanding Universe. It is shown that the results
are always finite if one puts in case of scalar particles creation a special
term into the Lagrangian. Numerical estimates of the effect of particle
creation are made. The role of creation of superheavy particles in cosmology is
discussed.
|
[
{
"created": "Tue, 7 Apr 2020 09:39:10 GMT",
"version": "v1"
}
] |
2020-04-08
|
[
[
"Grib",
"A. A.",
""
],
[
"Pavlov",
"Yu. V.",
""
]
] |
The problem of particle creation in cosmology concerning whether the results for the number of particles are infinite or finite is discussed for scalar and spinor particles in Friedmann expanding Universe. It is shown that the results are always finite if one puts in case of scalar particles creation a special term into the Lagrangian. Numerical estimates of the effect of particle creation are made. The role of creation of superheavy particles in cosmology is discussed.
|
1112.4420
|
Richard Woodard
|
E. O. Kahya (U. of Jena), S. P. Miao (U. of Utrecht) and R. P. Woodard
(U. of Florida)
|
The Coincidence Limit of the Graviton Propagator in de Donder Gauge on
de Sitter Background
|
41 pages, uses LaTeX 2e, version 2 has some typoes corrected
|
J.Math.Phys.53:022304,2012
|
10.1063/1.3681886
|
UFIFT-QG-11-05
|
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We explicitly work out the de Sitter breaking contributions to the recent
solution for the de Donder gauge graviton propagator on de Sitter. We also
provide explicit power series expansions for the two structure functions, which
are suitable for implementing dimensional regularization. And we evaluate the
coincidence limit of the propagator.
|
[
{
"created": "Mon, 19 Dec 2011 17:48:31 GMT",
"version": "v1"
},
{
"created": "Fri, 10 Feb 2012 16:03:25 GMT",
"version": "v2"
}
] |
2012-02-13
|
[
[
"Kahya",
"E. O.",
"",
"U. of Jena"
],
[
"Miao",
"S. P.",
"",
"U. of Utrecht"
],
[
"Woodard",
"R. P.",
"",
"U. of Florida"
]
] |
We explicitly work out the de Sitter breaking contributions to the recent solution for the de Donder gauge graviton propagator on de Sitter. We also provide explicit power series expansions for the two structure functions, which are suitable for implementing dimensional regularization. And we evaluate the coincidence limit of the propagator.
|
1011.3335
|
Christian R\"oken
|
Christian R\"oken
|
First-order quantum-gravitational correction to Friedmannian cosmology
from covariant, holomorphic spinfoam cosmology
| null |
International Journal of Modern Physics D Vol. 22, No. 0 (2013)
1350005
|
10.1142/S0218271813500053
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The first-order loop quantum gravity correction of the simplest, classical
general-relativistic Friedmann Hamiltonian constraint, emerging from a
holomorphic spinfoam cosmological model peaked on homogeneous, isotropic
geometries, is studied. The quantum Hamiltonian constraint, satisfied by the
EPRL transition amplitude between the boundary cosmological coherent states,
includes a contribution of the order of the Planck constant $\hbar$ that also
appears in the corresponding semiclassical symplectic model. The analysis of
this term gives a quantum-gravitational correction to the classical Friedmann
dynamics of the scale factor yielding a small decelerating expansion (small
accelerating contraction) of the universe. The robustness of the physical
interpretation is established for arbitrary refinements of the boundary graphs.
Also, mathematical equivalences between the semiclassical cosmological model
and certain classical fluid and scalar field theories are explored.
|
[
{
"created": "Mon, 15 Nov 2010 10:36:26 GMT",
"version": "v1"
},
{
"created": "Thu, 3 Mar 2011 11:22:27 GMT",
"version": "v2"
},
{
"created": "Sun, 6 Mar 2011 16:22:14 GMT",
"version": "v3"
},
{
"created": "Thu, 24 Nov 2011 15:12:00 GMT",
"version": "v4"
},
{
"created": "Tue, 2 Oct 2012 13:40:03 GMT",
"version": "v5"
},
{
"created": "Fri, 26 Jun 2015 12:09:57 GMT",
"version": "v6"
},
{
"created": "Wed, 1 Jul 2015 19:02:56 GMT",
"version": "v7"
}
] |
2015-07-02
|
[
[
"Röken",
"Christian",
""
]
] |
The first-order loop quantum gravity correction of the simplest, classical general-relativistic Friedmann Hamiltonian constraint, emerging from a holomorphic spinfoam cosmological model peaked on homogeneous, isotropic geometries, is studied. The quantum Hamiltonian constraint, satisfied by the EPRL transition amplitude between the boundary cosmological coherent states, includes a contribution of the order of the Planck constant $\hbar$ that also appears in the corresponding semiclassical symplectic model. The analysis of this term gives a quantum-gravitational correction to the classical Friedmann dynamics of the scale factor yielding a small decelerating expansion (small accelerating contraction) of the universe. The robustness of the physical interpretation is established for arbitrary refinements of the boundary graphs. Also, mathematical equivalences between the semiclassical cosmological model and certain classical fluid and scalar field theories are explored.
|
1202.1256
|
Roldao da Rocha
|
Roldao da Rocha, J. M. Hoff da SIlva
|
Black string corrections in variable tension braneworld scenarios
|
12 pages, 5 figures, accepted in PRD
|
Phys. Rev. D 85 (2012) 046009
|
10.1103/PhysRevD.85.046009
| null |
gr-qc hep-th math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Braneworld models with variable tension are investigated, and the corrections
on the black string horizon along the extra dimension are provided. Such
corrections are encrypted in additional terms involving the covariant
derivatives of the variable tension on the brane, providing profound
consequences concerning the black string horizon variation along the extra
dimension, near the brane. The black string horizon behavior is shown to be
drastically modified by the terms corrected by the brane variable tension. In
particular, a model motivated by the phenomenological interesting case
regarding Eotvos branes is investigated. It forthwith provides further physical
features regarding variable tension braneworld scenarios, heretofore concealed
in all previous analysis in the literature. All precedent analysis considered
uniquely the expansion of the metric up to the second order along the extra
dimension, what is able to evince solely the brane variable tension absolute
value. Notwithstanding, the expansion terms aftermath, further accomplished in
this paper from the third order on, elicits the successive covariant
derivatives of the brane variable tension, and their respective coupling with
the extrinsic curvature, the Weyl tensor, and the Riemann and Ricci tensors, as
well as the scalar curvature. Such additional terms are shown to provide sudden
modifications in the black string horizon in a variable tension braneworld
scenario
|
[
{
"created": "Mon, 6 Feb 2012 19:57:30 GMT",
"version": "v1"
}
] |
2012-02-27
|
[
[
"da Rocha",
"Roldao",
""
],
[
"da SIlva",
"J. M. Hoff",
""
]
] |
Braneworld models with variable tension are investigated, and the corrections on the black string horizon along the extra dimension are provided. Such corrections are encrypted in additional terms involving the covariant derivatives of the variable tension on the brane, providing profound consequences concerning the black string horizon variation along the extra dimension, near the brane. The black string horizon behavior is shown to be drastically modified by the terms corrected by the brane variable tension. In particular, a model motivated by the phenomenological interesting case regarding Eotvos branes is investigated. It forthwith provides further physical features regarding variable tension braneworld scenarios, heretofore concealed in all previous analysis in the literature. All precedent analysis considered uniquely the expansion of the metric up to the second order along the extra dimension, what is able to evince solely the brane variable tension absolute value. Notwithstanding, the expansion terms aftermath, further accomplished in this paper from the third order on, elicits the successive covariant derivatives of the brane variable tension, and their respective coupling with the extrinsic curvature, the Weyl tensor, and the Riemann and Ricci tensors, as well as the scalar curvature. Such additional terms are shown to provide sudden modifications in the black string horizon in a variable tension braneworld scenario
|
2206.04086
|
Ekapob Kulchoakrungsun
|
Ekapob Kulchoakrungsun, Ananya Mukherjee, Nishant Agarwal, Anthony R.
Pullen
|
Linear growth of structure in massive gravity
|
16 pages, 5 figures. Mathematica notebook supplement is enclosed in
the source file
|
Phys. Rev. D 106, 083527 (2022)
|
10.1103/PhysRevD.106.083527
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study background dynamics and the growth of matter perturbations in the
extended quasidilaton setup of massive gravity. For the analysis of
perturbations, we first choose a scalar field matter component and obtain the
conditions under which all scalar perturbations are stable. We work in unitary
gauge for the matter field, which allows us to directly map to known results in
the limit of general relativity. By performing a parameter search, we find that
the perturbations are unstable in general, while a particular choice of
potential, where the scalar field effectively behaves like pressureless matter,
allows for stable perturbations. We next consider the growth of matter
perturbations in a cold dark matter-dominated Universe. Working in conformal
Newtonian gauge, we obtain evolution equations for various observables
including the growth factor and growth rate, and find scale-independent growth
in the quasistatic and subhorizon approximations. We finally show how the
Hubble parameter and matter perturbations evolve in massive gravity for a
specific choice of parameter values, and how this evolution compares to the
standard cosmological model consisting of a cosmological constant and cold dark
matter.
|
[
{
"created": "Wed, 8 Jun 2022 18:00:07 GMT",
"version": "v1"
},
{
"created": "Fri, 28 Oct 2022 19:23:17 GMT",
"version": "v2"
}
] |
2022-11-01
|
[
[
"Kulchoakrungsun",
"Ekapob",
""
],
[
"Mukherjee",
"Ananya",
""
],
[
"Agarwal",
"Nishant",
""
],
[
"Pullen",
"Anthony R.",
""
]
] |
We study background dynamics and the growth of matter perturbations in the extended quasidilaton setup of massive gravity. For the analysis of perturbations, we first choose a scalar field matter component and obtain the conditions under which all scalar perturbations are stable. We work in unitary gauge for the matter field, which allows us to directly map to known results in the limit of general relativity. By performing a parameter search, we find that the perturbations are unstable in general, while a particular choice of potential, where the scalar field effectively behaves like pressureless matter, allows for stable perturbations. We next consider the growth of matter perturbations in a cold dark matter-dominated Universe. Working in conformal Newtonian gauge, we obtain evolution equations for various observables including the growth factor and growth rate, and find scale-independent growth in the quasistatic and subhorizon approximations. We finally show how the Hubble parameter and matter perturbations evolve in massive gravity for a specific choice of parameter values, and how this evolution compares to the standard cosmological model consisting of a cosmological constant and cold dark matter.
|
2202.12828
|
Jibril Ben Achour
|
Jibril Ben Achour, Etera R. Livine, Shinji Mukohyama and Jean-Philippe
Uzan
|
Hidden symmetry of the static response of black holes: Applications to
Love numbers
|
22+5 pages, clarifications added on the symmetry criterion, extension
to Kerr added in Appendix, version published in JHEP
| null | null |
YITP-22-17, IPMU22-0003
|
gr-qc hep-th
|
http://creativecommons.org/licenses/by/4.0/
|
We show that any static linear perturbations around Schwarzschild black holes
enjoy a set of conserved charges which forms a centrally extended
Schr\"{o}dinger algebra sh(1) = sl$(2,\mathbb{R}) \ltimes \mathcal{H}$. The
central charge is given by the black hole mass, echoing results on black hole
entropy from near-horizon diffeomorphism symmetry. The finite symmetry
transformations generated by these conserved charges correspond to Galilean and
conformal transformations of the static field and of the coordinates. This new
structure allows one to discuss the static response of a Schwarzschild black
hole in the test field approximation from a symmetry-based approach. First we
show that the (horizontal) symmetry protecting the vanishing of the Love
numbers recently exhibited by Hui et al, dubbed the HJPSS symmetry, coincides
with one of the sl$(2,\mathbb{R})$ generators of the Schr\"{o}dinger group.
Then, it is demonstrated that the HJPSS symmetry is selected thanks to the
spontaneous breaking of the full Schr\"{o}dinger symmetry at the horizon down
to a simple abelian sub-group. The latter can be understood as the symmetry
protecting the regularity of the test field at the horizon. In the
4-dimensional case, this provides a symmetry protection for the vanishing of
the Schwarzschild Love numbers. Our results trivially extend to the Kerr case.
|
[
{
"created": "Fri, 25 Feb 2022 17:15:55 GMT",
"version": "v1"
},
{
"created": "Fri, 15 Jul 2022 07:13:36 GMT",
"version": "v2"
}
] |
2022-07-18
|
[
[
"Achour",
"Jibril Ben",
""
],
[
"Livine",
"Etera R.",
""
],
[
"Mukohyama",
"Shinji",
""
],
[
"Uzan",
"Jean-Philippe",
""
]
] |
We show that any static linear perturbations around Schwarzschild black holes enjoy a set of conserved charges which forms a centrally extended Schr\"{o}dinger algebra sh(1) = sl$(2,\mathbb{R}) \ltimes \mathcal{H}$. The central charge is given by the black hole mass, echoing results on black hole entropy from near-horizon diffeomorphism symmetry. The finite symmetry transformations generated by these conserved charges correspond to Galilean and conformal transformations of the static field and of the coordinates. This new structure allows one to discuss the static response of a Schwarzschild black hole in the test field approximation from a symmetry-based approach. First we show that the (horizontal) symmetry protecting the vanishing of the Love numbers recently exhibited by Hui et al, dubbed the HJPSS symmetry, coincides with one of the sl$(2,\mathbb{R})$ generators of the Schr\"{o}dinger group. Then, it is demonstrated that the HJPSS symmetry is selected thanks to the spontaneous breaking of the full Schr\"{o}dinger symmetry at the horizon down to a simple abelian sub-group. The latter can be understood as the symmetry protecting the regularity of the test field at the horizon. In the 4-dimensional case, this provides a symmetry protection for the vanishing of the Schwarzschild Love numbers. Our results trivially extend to the Kerr case.
|
2108.07172
|
Slava G. Turyshev
|
Slava G. Turyshev, Viktor T. Toth
|
Recovering the mass distribution of an extended gravitational lens
|
21 pages, 11 figures, 1 table
|
MNRAS 513(4), 5355-5376 (2022)
|
10.1093/mnras/stac1174
| null |
gr-qc astro-ph.IM physics.optics
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We investigate the possibility of determining the mass distribution of a
gravitational lens via lensing observations. We consider an extended, compact
gravitational lens, representing its static external gravitational potential
via an infinite set of symmetric trace free (STF) multipole moments. Within the
wave-optical treatment, we evaluate the caustics formed in the lens's point
spread function (PSF). We study the only quantity that is available in
astronomical lensing observations: the image of that PSF formed by an imaging
telescope. This observable may be used to recover some physical characteristics
of the lens, including its shape, orientation and composition. Illustrating
this, we study exotic gravitational lenses formed by several well-known solids
with uniform density. We show that when moments beyond the quadrupole are
observed, some of the symmetry properties of the lens can be recovered. The
presence of an octupole moment implies breaking the "north-south" symmetry of
the mass distribution in the lens. The presence of a rotated hexadecapole
moment implies breaking axial symmetry. As such, if observations of lensed
images allow the reconstruction of these moments, important information about
the mass distribution and dynamics of the lens can be obtained. This may help
with choosing the most appropriate mass profile that is used to characterize
the mass distribution of astrophysical lenses, such as the dark matter halos
that are presumed to contain most of the mass of galaxies and clusters of
galaxies. Our results are novel and offer new insight into gravitational
lensing by realistic astrophysical systems.
|
[
{
"created": "Mon, 16 Aug 2021 15:33:42 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Feb 2022 01:29:17 GMT",
"version": "v2"
},
{
"created": "Fri, 29 Apr 2022 15:53:34 GMT",
"version": "v3"
}
] |
2022-06-06
|
[
[
"Turyshev",
"Slava G.",
""
],
[
"Toth",
"Viktor T.",
""
]
] |
We investigate the possibility of determining the mass distribution of a gravitational lens via lensing observations. We consider an extended, compact gravitational lens, representing its static external gravitational potential via an infinite set of symmetric trace free (STF) multipole moments. Within the wave-optical treatment, we evaluate the caustics formed in the lens's point spread function (PSF). We study the only quantity that is available in astronomical lensing observations: the image of that PSF formed by an imaging telescope. This observable may be used to recover some physical characteristics of the lens, including its shape, orientation and composition. Illustrating this, we study exotic gravitational lenses formed by several well-known solids with uniform density. We show that when moments beyond the quadrupole are observed, some of the symmetry properties of the lens can be recovered. The presence of an octupole moment implies breaking the "north-south" symmetry of the mass distribution in the lens. The presence of a rotated hexadecapole moment implies breaking axial symmetry. As such, if observations of lensed images allow the reconstruction of these moments, important information about the mass distribution and dynamics of the lens can be obtained. This may help with choosing the most appropriate mass profile that is used to characterize the mass distribution of astrophysical lenses, such as the dark matter halos that are presumed to contain most of the mass of galaxies and clusters of galaxies. Our results are novel and offer new insight into gravitational lensing by realistic astrophysical systems.
|
2001.02126
|
Valerio Faraoni
|
Valerio Faraoni (Bishop's University)
|
A symmetry of the Einstein-Friedmann equations for spatially flat,
perfect fluid, universes
|
10 pages. Invited contribution to appear in a special issue of
Symmetry edited by S. Nojiri and T. Katsuragawa
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We report a symmetry property of the Einstein-Friedmann equations for
spatially flat Friedmann-Lema\^itre-Robertson-Walker universes filled with a
perfect fluid with any constant equation of state. The symmetry transformations
form a one-parameter Abelian group.
|
[
{
"created": "Tue, 7 Jan 2020 15:38:56 GMT",
"version": "v1"
}
] |
2020-01-08
|
[
[
"Faraoni",
"Valerio",
"",
"Bishop's University"
]
] |
We report a symmetry property of the Einstein-Friedmann equations for spatially flat Friedmann-Lema\^itre-Robertson-Walker universes filled with a perfect fluid with any constant equation of state. The symmetry transformations form a one-parameter Abelian group.
|
1803.05341
|
Thomas B\"ackdahl
|
Steffen Aksteiner and Thomas B\"ackdahl
|
All local gauge invariants for perturbations of the Kerr spacetime
|
5 pages. Updated references
|
Phys. Rev. Lett. 121, 051104 (2018)
|
10.1103/PhysRevLett.121.051104
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present two complex scalar gauge invariants for perturbations of the Kerr
spacetime defined covariantly in terms of the Killing vectors and the conformal
Killing-Yano tensor of the background together with the linearized curvature
and its first derivatives. These invariants are in particular sensitive to
variations of the Kerr parameters. Together with the Teukolsky scalars and the
linearized Ricci tensor they form a minimal set that generates all local gauge
invariants. We also present curvature invariants that reduce to the gauge
invariants in linearized theory.
|
[
{
"created": "Wed, 14 Mar 2018 15:08:49 GMT",
"version": "v1"
},
{
"created": "Thu, 2 Aug 2018 18:56:53 GMT",
"version": "v2"
}
] |
2018-08-06
|
[
[
"Aksteiner",
"Steffen",
""
],
[
"Bäckdahl",
"Thomas",
""
]
] |
We present two complex scalar gauge invariants for perturbations of the Kerr spacetime defined covariantly in terms of the Killing vectors and the conformal Killing-Yano tensor of the background together with the linearized curvature and its first derivatives. These invariants are in particular sensitive to variations of the Kerr parameters. Together with the Teukolsky scalars and the linearized Ricci tensor they form a minimal set that generates all local gauge invariants. We also present curvature invariants that reduce to the gauge invariants in linearized theory.
|
1207.4339
|
Alexander Zhuk
|
Maxim Eingorn, Seyed Hossein Fakhr and Alexander Zhuk
|
Observational constraints on Kaluza-Klein models with $d$-dimensional
spherical compactification
|
6 pages
| null | null | null |
gr-qc astro-ph.HE hep-ph hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We investigate Kaluza-Klein models in the case of spherical compactification
of the internal space with an arbitrary number of dimensions. The gravitating
source has the dust-like equation of state in the external/our space and an
arbitrary equation of state (with the parameter $\Omega$) in the internal
space. We get the perturbed (up to $O(1/c^2)$) metric coefficients. For the
external space, these coefficients consist of two parts: the standard general
relativity expressions plus the admixture of the Yukawa interaction. This
admixture takes place only for some certain condition which is equivalent to
the condition for the internal space stabilization. We demonstrate that the
mass of the Yukawa interaction is defined by the mass of the
gravexciton/radion. In the Solar system, the Yukawa mass is big enough for
dropping the admixture of this interaction and getting good agreement with the
gravitational tests for any value of $\Omega$. However, the gravitating body
acquires the effective relativistic pressure in the external space which
vanishes only in the case of tension $\Omega=-1/2$ in the internal space.
|
[
{
"created": "Wed, 18 Jul 2012 11:06:00 GMT",
"version": "v1"
}
] |
2012-07-19
|
[
[
"Eingorn",
"Maxim",
""
],
[
"Fakhr",
"Seyed Hossein",
""
],
[
"Zhuk",
"Alexander",
""
]
] |
We investigate Kaluza-Klein models in the case of spherical compactification of the internal space with an arbitrary number of dimensions. The gravitating source has the dust-like equation of state in the external/our space and an arbitrary equation of state (with the parameter $\Omega$) in the internal space. We get the perturbed (up to $O(1/c^2)$) metric coefficients. For the external space, these coefficients consist of two parts: the standard general relativity expressions plus the admixture of the Yukawa interaction. This admixture takes place only for some certain condition which is equivalent to the condition for the internal space stabilization. We demonstrate that the mass of the Yukawa interaction is defined by the mass of the gravexciton/radion. In the Solar system, the Yukawa mass is big enough for dropping the admixture of this interaction and getting good agreement with the gravitational tests for any value of $\Omega$. However, the gravitating body acquires the effective relativistic pressure in the external space which vanishes only in the case of tension $\Omega=-1/2$ in the internal space.
|
2001.00252
|
Gernot Hei{\ss}el
|
David Fajman and Gernot Hei{\ss}el and Maciej Maliborski
|
On the oscillations and future asymptotics of locally rotationally
symmetric Bianchi type III cosmologies with a massive scalar field
|
25 pages, 6 figures. To be published in Classical and Qunatum Gravity
- IOP. The new version includes small changes motivated by the helpful
comments of the referees. In particular, we now give more information on the
asymptotics of the scalar field
| null |
10.1088/1361-6382/ab8c97
| null |
gr-qc math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We analyse spatially homogenous cosmological models of locally rotationally
symmetric Bianchi type III with a massive scalar field as matter model. Our
main result concerns the future asymptotics of these spacetimes and gives the
dominant time behaviour of the metric and the scalar field for all solutions
for late times. This metric is forever expanding in all directions, however in
one spatial direction only at a logarithmic rate, while at a power-law rate in
the other two. Although the energy density goes to zero, it is matter dominated
in the sense that the metric components differ qualitatively from the
corresponding vacuum future asymptotics.
Our results rely on a conjecture for which we give strong analytical and
numerical support. For this we apply methods from the theory of averaging in
nonlinear dynamical systems. This allows us to control the oscillations
entering the system through the scalar field by the Klein-Gordon equation in a
perturbative approach.
|
[
{
"created": "Wed, 1 Jan 2020 17:53:33 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Apr 2020 12:00:36 GMT",
"version": "v2"
}
] |
2020-08-26
|
[
[
"Fajman",
"David",
""
],
[
"Heißel",
"Gernot",
""
],
[
"Maliborski",
"Maciej",
""
]
] |
We analyse spatially homogenous cosmological models of locally rotationally symmetric Bianchi type III with a massive scalar field as matter model. Our main result concerns the future asymptotics of these spacetimes and gives the dominant time behaviour of the metric and the scalar field for all solutions for late times. This metric is forever expanding in all directions, however in one spatial direction only at a logarithmic rate, while at a power-law rate in the other two. Although the energy density goes to zero, it is matter dominated in the sense that the metric components differ qualitatively from the corresponding vacuum future asymptotics. Our results rely on a conjecture for which we give strong analytical and numerical support. For this we apply methods from the theory of averaging in nonlinear dynamical systems. This allows us to control the oscillations entering the system through the scalar field by the Klein-Gordon equation in a perturbative approach.
|
1106.1316
|
Thomas Sch\"onenbach
|
Thomas Sch\"onenbach
|
Die Kerr-Metrik in pseudokomplexer Allgemeiner Relativit\"atstheorie
|
Master Thesis
| null | null | null |
gr-qc
|
http://creativecommons.org/licenses/by-nc-sa/3.0/
|
This is a master thesis concerning the search for a Kerr-type metric in the
pseudocomplex General Relativity. Two different ways of deriving the standard
Kerr-metric are presented and a solution for a Kerr-type metric in the
pseudocomplex formalism is found.
|
[
{
"created": "Tue, 7 Jun 2011 11:25:33 GMT",
"version": "v1"
}
] |
2011-06-08
|
[
[
"Schönenbach",
"Thomas",
""
]
] |
This is a master thesis concerning the search for a Kerr-type metric in the pseudocomplex General Relativity. Two different ways of deriving the standard Kerr-metric are presented and a solution for a Kerr-type metric in the pseudocomplex formalism is found.
|
gr-qc/0103064
|
Emilio Elizalde
|
E. Elizalde and Sergi R. Hildebrandt
|
A family of quantum interiors for ordinary and stringy black holes II:
Geometric considerations and global properties
|
latex, 21 pages
| null | null | null |
gr-qc astro-ph hep-th math-ph math.MP
| null |
A family of spacetimes suitable for describing the matter conditions of a
static, spherically symmetric quantum vacuum is studied, as well as its
reliability for describing a regular model for the interior of a semiclassical,
static black hole ---without ever invoking a mass shell for the final object.
In paper I, this condition was seen to limit the search to only one,
distinguished family, that was investigated in detail. Here it will be proven
that, aside from being mathematically generic (in its uniqueness), this family
exhibits beautiful physical properties, that one would reasonably demand from a
collapse process, including the remarkable result that isotropization may take
place conveniently far from the (unavoidable) regularization scale. The
analysis is also extended in order to include the possibility of a stringy
core, always within the limits imposed by the semiclassical approach to
gravitation. This constitutes a first approximation to the final goal of trying
to characterize a regular, self-gravitating, stringy black hole.
|
[
{
"created": "Fri, 16 Mar 2001 17:08:40 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Elizalde",
"E.",
""
],
[
"Hildebrandt",
"Sergi R.",
""
]
] |
A family of spacetimes suitable for describing the matter conditions of a static, spherically symmetric quantum vacuum is studied, as well as its reliability for describing a regular model for the interior of a semiclassical, static black hole ---without ever invoking a mass shell for the final object. In paper I, this condition was seen to limit the search to only one, distinguished family, that was investigated in detail. Here it will be proven that, aside from being mathematically generic (in its uniqueness), this family exhibits beautiful physical properties, that one would reasonably demand from a collapse process, including the remarkable result that isotropization may take place conveniently far from the (unavoidable) regularization scale. The analysis is also extended in order to include the possibility of a stringy core, always within the limits imposed by the semiclassical approach to gravitation. This constitutes a first approximation to the final goal of trying to characterize a regular, self-gravitating, stringy black hole.
|
1307.6800
|
Harvey S. Reall
|
Keiju Murata, Harvey S. Reall and Norihiro Tanahashi
|
What happens at the horizon(s) of an extreme black hole?
|
33 pages plus appendices
| null |
10.1088/0264-9381/30/23/235007
|
IPMU13-0144
|
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A massless scalar field exhibits an instability at the event horizon of an
extreme black hole. We study numerically the nonlinear evolution of this
instability for spherically symmetric perturbations of an extreme
Reissner-Nordstrom (RN) black hole. We find that generically the endpoint of
the instability is a non-extreme RN solution. However, there exist fine-tuned
initial perturbations for which the instability never decays. In this case, the
perturbed spacetime describes a time-dependent extreme black hole. Such
solutions settle down to extreme RN outside, but not on, the event horizon. The
event horizon remains smooth but certain observers who cross it at late time
experience large gradients there. Our results indicate that these dynamical
extreme black holes admit a C^1 extension across an inner (Cauchy) horizon.
|
[
{
"created": "Thu, 25 Jul 2013 15:46:51 GMT",
"version": "v1"
}
] |
2015-06-16
|
[
[
"Murata",
"Keiju",
""
],
[
"Reall",
"Harvey S.",
""
],
[
"Tanahashi",
"Norihiro",
""
]
] |
A massless scalar field exhibits an instability at the event horizon of an extreme black hole. We study numerically the nonlinear evolution of this instability for spherically symmetric perturbations of an extreme Reissner-Nordstrom (RN) black hole. We find that generically the endpoint of the instability is a non-extreme RN solution. However, there exist fine-tuned initial perturbations for which the instability never decays. In this case, the perturbed spacetime describes a time-dependent extreme black hole. Such solutions settle down to extreme RN outside, but not on, the event horizon. The event horizon remains smooth but certain observers who cross it at late time experience large gradients there. Our results indicate that these dynamical extreme black holes admit a C^1 extension across an inner (Cauchy) horizon.
|
2305.18041
|
Serge Repin Mr.
|
Mikhail A. Bugaev, Igor D. Novikov, Serge V. Repin, Polina S.
Samorodskaya
|
Uniform sky glow (CMB) observed through the throat of a wormhole
|
7 pages, 7 figures
| null | null | null |
gr-qc
|
http://creativecommons.org/publicdomain/zero/1.0/
|
The problem of the possibility of observing a uniform sky glow through the
throat of a Morris--Thorne wormhole by an observer located in another
asymptotically flat space-time is considered. It is shown that an individual
star has multiple images, and the image of a luminous sky has a complex
structure and contains ring structures. The reasons for the emergence of such
structures are considered. The distribution of radiation intensity in the image
along the radial coordinate is constructed.In addition, an image of the
Morris-Thorne wormhole was constructed against the background of uniform sky
radiation in the observer's space. A comparison to observations can be made by
producing a synthetic Morris-Thorne type wormhole image against a CMB
background. This image has been constructed by a combination of the images for
inner and outer areas.
|
[
{
"created": "Mon, 29 May 2023 12:10:36 GMT",
"version": "v1"
}
] |
2023-05-30
|
[
[
"Bugaev",
"Mikhail A.",
""
],
[
"Novikov",
"Igor D.",
""
],
[
"Repin",
"Serge V.",
""
],
[
"Samorodskaya",
"Polina S.",
""
]
] |
The problem of the possibility of observing a uniform sky glow through the throat of a Morris--Thorne wormhole by an observer located in another asymptotically flat space-time is considered. It is shown that an individual star has multiple images, and the image of a luminous sky has a complex structure and contains ring structures. The reasons for the emergence of such structures are considered. The distribution of radiation intensity in the image along the radial coordinate is constructed.In addition, an image of the Morris-Thorne wormhole was constructed against the background of uniform sky radiation in the observer's space. A comparison to observations can be made by producing a synthetic Morris-Thorne type wormhole image against a CMB background. This image has been constructed by a combination of the images for inner and outer areas.
|
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