id stringlengths 9 13 | submitter stringlengths 1 64 ⌀ | authors stringlengths 5 22.9k | title stringlengths 4 245 | comments stringlengths 1 548 ⌀ | journal-ref stringlengths 4 362 ⌀ | doi stringlengths 12 82 ⌀ | report-no stringlengths 2 281 ⌀ | categories stringclasses 793 values | license stringclasses 9 values | orig_abstract stringlengths 24 1.95k | versions listlengths 1 30 | update_date stringlengths 10 10 | authors_parsed listlengths 1 1.74k | abstract stringlengths 21 1.95k |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
2110.05938 | Pascal Koiran | Pascal Koiran | Infall time in the Eddington-Finkelstein metric, with application to
Einstein-Rosen bridges | To appear in International Journal of Modern Physics D | null | 10.1142/S0218271821501066 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Eddington-Finkelstein metric is obtained from the Schwarzschild metric by
a change of the time variable. It is well known that a test mass falling into a
black hole does not reach the event horizon for any finite value of the
Schwarzschild time variable $t$. By contrast, we show that the event horizon is
reached for a finite value of the Eddington-Finkelstein time variable $t'$.
Then we study in Eddington-Finkelstein time the fate of a massive particle
traversing an Einstein-Rosen bridge and obtain a different conclusion than
recent proposals in the literature: we show that the particle reaches the
wormhole throat for a finite value $t'_1$ of the time marker $t'$, and
continues its trajectory across the throat for $t'>t'_1$. Such a behavior does
not make sense in Schwarzschild time since it would amount to continuing the
trajectory of the particle "beyond the end of time."
| [
{
"created": "Sat, 9 Oct 2021 15:35:11 GMT",
"version": "v1"
}
] | 2021-10-13 | [
[
"Koiran",
"Pascal",
""
]
] | The Eddington-Finkelstein metric is obtained from the Schwarzschild metric by a change of the time variable. It is well known that a test mass falling into a black hole does not reach the event horizon for any finite value of the Schwarzschild time variable $t$. By contrast, we show that the event horizon is reached for a finite value of the Eddington-Finkelstein time variable $t'$. Then we study in Eddington-Finkelstein time the fate of a massive particle traversing an Einstein-Rosen bridge and obtain a different conclusion than recent proposals in the literature: we show that the particle reaches the wormhole throat for a finite value $t'_1$ of the time marker $t'$, and continues its trajectory across the throat for $t'>t'_1$. Such a behavior does not make sense in Schwarzschild time since it would amount to continuing the trajectory of the particle "beyond the end of time." |
gr-qc/0111026 | Sergio M. C. V. Goncalves | Sergio M. C. V. Goncalves (Yale), Sanjay Jhingan (YITP, Japan), and
Giulio Magli (Milano, Italy) | The spectrum of endstates of gravitational collapse with tangential
stresses | 9 pages, revtex4; accepted for publication in Phys. Rev. D | Phys.Rev. D65 (2002) 064011 | 10.1103/PhysRevD.65.064011 | null | gr-qc | null | The final state--black hole or naked singularity--of the gravitational
collapse of a marginally bound matter configuration in the presence of
tangential stresses is classified, in full generality, in terms of the initial
data and equation of state. If the tangential pressure is sufficiently strong,
configurations that would otherwise evolve to a spacelike singularity, result
in a locally naked singularity, both in the homogeneous and in the general,
inhomogeneous density case.
| [
{
"created": "Thu, 8 Nov 2001 17:14:35 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Goncalves",
"Sergio M. C. V.",
"",
"Yale"
],
[
"Jhingan",
"Sanjay",
"",
"YITP, Japan"
],
[
"Magli",
"Giulio",
"",
"Milano, Italy"
]
] | The final state--black hole or naked singularity--of the gravitational collapse of a marginally bound matter configuration in the presence of tangential stresses is classified, in full generality, in terms of the initial data and equation of state. If the tangential pressure is sufficiently strong, configurations that would otherwise evolve to a spacelike singularity, result in a locally naked singularity, both in the homogeneous and in the general, inhomogeneous density case. |
gr-qc/9905104 | Dzhunushaliev Vladimir | V. Dzhunushaliev and D. Singleton | Experimental test for extra dimensions in Kaluza-Klein gravity | 11 pages, 3 PS.figures, REVTEX, the quality of the figures are
improved | Gen.Rel.Grav. 32 (2000) 271-280 | 10.1023/A:1001943725858 | null | gr-qc | null | 5D Kaluza-Klein gravity has several nonasymptotically flat solutions which
generally, possessed both electric and magnetic charges. In this paper we
suggest that these solutions can act as quantum virtual handles (wormholes) in
spacetime foam models. By applying a sufficently large, external electric
and/or magnetic field it may be possible to ``inflate'' these solutions from a
quantum to a classical state. This effect would lead to a possible experimental
signal for higher dimensions in multidimensional gravity.
| [
{
"created": "Fri, 28 May 1999 08:00:33 GMT",
"version": "v1"
},
{
"created": "Mon, 7 Feb 2000 09:21:17 GMT",
"version": "v2"
}
] | 2015-06-25 | [
[
"Dzhunushaliev",
"V.",
""
],
[
"Singleton",
"D.",
""
]
] | 5D Kaluza-Klein gravity has several nonasymptotically flat solutions which generally, possessed both electric and magnetic charges. In this paper we suggest that these solutions can act as quantum virtual handles (wormholes) in spacetime foam models. By applying a sufficently large, external electric and/or magnetic field it may be possible to ``inflate'' these solutions from a quantum to a classical state. This effect would lead to a possible experimental signal for higher dimensions in multidimensional gravity. |
0909.3924 | Junko Ohashi | Junko Ohashi, Shinji Tsujikawa | Assisted dark energy | 14 pages, 12 figures, version to appear in Physical Review D | Phys.Rev.D80:103513,2009 | 10.1103/PhysRevD.80.103513 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Cosmological scaling solutions, which give rise to a scalar-field density
proportional to a background fluid density during radiation and matter eras,
are attractive to alleviate the energy scale problem of dark energy. In the
presence of multiple scalar fields the scaling solution can exit to the epoch
of cosmic acceleration through the so-called assisted inflation mechanism. We
study cosmological dynamics of a multi-field system in details with a general
Lagrangian density p=sum_{i=1}^n X_i g(X_i e^{lambda_i phi_i}), where
X_i=-(nabla phi_i)^2/2 is the kinetic energy of the i-th field phi_i, lambda_i
is a constant, and g is an arbitrary function in terms of Y_i=X_i e^{lambda_i
phi_i}. This covers most of the scalar-field models of dark energy proposed in
literature that possess scaling solutions. Using the bound coming from
Big-Bang-Nucleosynthesis and the condition under which the each field cannot
drive inflation as a single component of the universe, we find the following
features: (i) a transient or eternal cosmic acceleration can be realized after
the scaling matter era, (ii) a "thawing" property of assisting scalar fields is
crucial to determine the evolution of the field equation of state w_{phi}, and
(iii) the field equation of state today can be consistent with the
observational bound w_{phi}<-0.8 in the presence of multiple scalar fields.
| [
{
"created": "Tue, 22 Sep 2009 07:30:02 GMT",
"version": "v1"
},
{
"created": "Fri, 23 Oct 2009 12:31:42 GMT",
"version": "v2"
}
] | 2010-03-25 | [
[
"Ohashi",
"Junko",
""
],
[
"Tsujikawa",
"Shinji",
""
]
] | Cosmological scaling solutions, which give rise to a scalar-field density proportional to a background fluid density during radiation and matter eras, are attractive to alleviate the energy scale problem of dark energy. In the presence of multiple scalar fields the scaling solution can exit to the epoch of cosmic acceleration through the so-called assisted inflation mechanism. We study cosmological dynamics of a multi-field system in details with a general Lagrangian density p=sum_{i=1}^n X_i g(X_i e^{lambda_i phi_i}), where X_i=-(nabla phi_i)^2/2 is the kinetic energy of the i-th field phi_i, lambda_i is a constant, and g is an arbitrary function in terms of Y_i=X_i e^{lambda_i phi_i}. This covers most of the scalar-field models of dark energy proposed in literature that possess scaling solutions. Using the bound coming from Big-Bang-Nucleosynthesis and the condition under which the each field cannot drive inflation as a single component of the universe, we find the following features: (i) a transient or eternal cosmic acceleration can be realized after the scaling matter era, (ii) a "thawing" property of assisting scalar fields is crucial to determine the evolution of the field equation of state w_{phi}, and (iii) the field equation of state today can be consistent with the observational bound w_{phi}<-0.8 in the presence of multiple scalar fields. |
0804.3157 | Guillermo A. Mena Marugan | M. Martin-Benito, G. A. Mena Marugan, and T. Pawlowski | Loop Quantization of Vacuum Bianchi I Cosmology | 10 pages, version accepted for publication in Physical Review D | Phys.Rev.D78:064008,2008 | 10.1103/PhysRevD.78.064008 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyze the loop quantization of the family of vacuum Bianchi I
spacetimes, a gravitational system whose classical solutions describe
homogeneous anisotropic cosmologies. We rigorously construct the operator that
represents the Hamiltonian constraint, showing that the states of zero volume
completely decouple from the rest of quantum states. This fact ensures that the
classical cosmological singularity is resolved in the quantum theory. In
addition, this allows us to adopt an equivalent quantum description in terms of
a well defined densitized Hamiltonian constraint. This latter constraint can be
regarded in a certain sense as a difference evolution equation in an internal
time provided by one of the triad components, which is polymerically quantized.
Generically, this evolution equation is a relation between the projection of
the quantum states in three different sections of constant internal time.
Nevertheless, around the initial singularity the equation involves only the two
closest sections with the same orientation of the triad. This has a double
effect: on the one hand, physical states are determined just by the data on one
section, on the other hand, the evolution defined in this way never crosses the
singularity, without the need of any special boundary condition. Finally, we
provide these physical states with a Hilbert structure, completing the
quantization.
| [
{
"created": "Sat, 19 Apr 2008 16:21:01 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Aug 2008 12:28:29 GMT",
"version": "v2"
}
] | 2009-02-20 | [
[
"Martin-Benito",
"M.",
""
],
[
"Marugan",
"G. A. Mena",
""
],
[
"Pawlowski",
"T.",
""
]
] | We analyze the loop quantization of the family of vacuum Bianchi I spacetimes, a gravitational system whose classical solutions describe homogeneous anisotropic cosmologies. We rigorously construct the operator that represents the Hamiltonian constraint, showing that the states of zero volume completely decouple from the rest of quantum states. This fact ensures that the classical cosmological singularity is resolved in the quantum theory. In addition, this allows us to adopt an equivalent quantum description in terms of a well defined densitized Hamiltonian constraint. This latter constraint can be regarded in a certain sense as a difference evolution equation in an internal time provided by one of the triad components, which is polymerically quantized. Generically, this evolution equation is a relation between the projection of the quantum states in three different sections of constant internal time. Nevertheless, around the initial singularity the equation involves only the two closest sections with the same orientation of the triad. This has a double effect: on the one hand, physical states are determined just by the data on one section, on the other hand, the evolution defined in this way never crosses the singularity, without the need of any special boundary condition. Finally, we provide these physical states with a Hilbert structure, completing the quantization. |
gr-qc/0008065 | Lior M. Burko | Lior M. Burko (Caltech), Yuk Tung Liu (Caltech), and Yoav Soen
(Technion) | Self force on charges in the spacetime of spherical shells | 23 pages, 7 Encapsulated PostScript figures, RevTeX | Phys.Rev. D63 (2001) 024015 | 10.1103/PhysRevD.63.024015 | null | gr-qc | null | We study the self force acting on static electric or scalar charges inside or
outside a spherical, massive, thin shell. The regularization of the self force
is done using the recently-proposed Mode Sum Regularization Prescription. In
all cases the self force acting on the charge is repulsive. We find that in the
scalar case the force is quadratic in the mass of the shell, and is a second
post-Newtonian effect. For the electric case the force is linear in the shell's
mass, and is a first post-Newtonian effect. When the charge is outside the
shell our results correct the known zero self force in the scalar case or the
known repulsive, inverse-cubic force law in the electric case, for the finite
size of the shell. When the charge is near the center of the shell the charge
undergoes harmonic oscillations.
| [
{
"created": "Sun, 27 Aug 2000 22:19:37 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Burko",
"Lior M.",
"",
"Caltech"
],
[
"Liu",
"Yuk Tung",
"",
"Caltech"
],
[
"Soen",
"Yoav",
"",
"Technion"
]
] | We study the self force acting on static electric or scalar charges inside or outside a spherical, massive, thin shell. The regularization of the self force is done using the recently-proposed Mode Sum Regularization Prescription. In all cases the self force acting on the charge is repulsive. We find that in the scalar case the force is quadratic in the mass of the shell, and is a second post-Newtonian effect. For the electric case the force is linear in the shell's mass, and is a first post-Newtonian effect. When the charge is outside the shell our results correct the known zero self force in the scalar case or the known repulsive, inverse-cubic force law in the electric case, for the finite size of the shell. When the charge is near the center of the shell the charge undergoes harmonic oscillations. |
2111.07704 | Sourav Chowdhury Roy | Sourav Roy Chowdhury, Maxim Khlopov | Gravitational waves in the modified gravity | Prepared for Proceedings of XXIV Bled Workshop | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We have taken a modified version of the Einstein Hilbert action, $ f(R,
T^\phi) $ gravity under consideration, where $T^\phi$ is the energy-momentum
tensor trace for the scalar field under consideration. The structural behaviour
of the scalar field considered varies with the form of the potential. The
number of polarization modes of gravitational waves in modified theories has
been studied extensively for the corresponding fields. There are two additional
scalar modes, in addition to the usual two transverse-traceless tensor modes
found in general relativity: a massive longitudinal mode and a massless
transverse mode (the breathing mode).
| [
{
"created": "Mon, 15 Nov 2021 12:21:03 GMT",
"version": "v1"
},
{
"created": "Fri, 19 Nov 2021 06:37:07 GMT",
"version": "v2"
}
] | 2021-11-22 | [
[
"Chowdhury",
"Sourav Roy",
""
],
[
"Khlopov",
"Maxim",
""
]
] | We have taken a modified version of the Einstein Hilbert action, $ f(R, T^\phi) $ gravity under consideration, where $T^\phi$ is the energy-momentum tensor trace for the scalar field under consideration. The structural behaviour of the scalar field considered varies with the form of the potential. The number of polarization modes of gravitational waves in modified theories has been studied extensively for the corresponding fields. There are two additional scalar modes, in addition to the usual two transverse-traceless tensor modes found in general relativity: a massive longitudinal mode and a massless transverse mode (the breathing mode). |
1405.1378 | Zeeshan Yousaf | M. Sharif and Z. Yousaf | Stability of a Class of Non-Static Axial Self-Gravitating Systems in
$f(R)$ Gravity | Astrophysics and Space Science, 24 pages | Astrophys. Space Sci. 352(2014)943 | 10.1007/s10509-014-1985-9 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we analyze stability regions of a non-static restricted class
of axially symmetric spacetime with anisotropic matter distribution. We
consider $f(R)=R+{\epsilon}R^2$ model and assume hydrostatic equilibrium of the
axial self-gravitating system at large past time. Considering perturbation from
hydrostatic phase, we develop dynamical as well as collapse equations and
explore dynamical instabilities at Newtonian and post-Newtonian regimes. It is
concluded with the help of stiffness parameter, $\Gamma_1$, that radial profile
of physical parameters like pressure anisotropy, energy density and higher
curvature terms of the $f(R)$ model affect the instability ranges.
| [
{
"created": "Tue, 3 Dec 2013 09:44:39 GMT",
"version": "v1"
},
{
"created": "Wed, 7 May 2014 03:30:08 GMT",
"version": "v2"
},
{
"created": "Tue, 3 Jun 2014 11:18:07 GMT",
"version": "v3"
}
] | 2014-11-19 | [
[
"Sharif",
"M.",
""
],
[
"Yousaf",
"Z.",
""
]
] | In this paper, we analyze stability regions of a non-static restricted class of axially symmetric spacetime with anisotropic matter distribution. We consider $f(R)=R+{\epsilon}R^2$ model and assume hydrostatic equilibrium of the axial self-gravitating system at large past time. Considering perturbation from hydrostatic phase, we develop dynamical as well as collapse equations and explore dynamical instabilities at Newtonian and post-Newtonian regimes. It is concluded with the help of stiffness parameter, $\Gamma_1$, that radial profile of physical parameters like pressure anisotropy, energy density and higher curvature terms of the $f(R)$ model affect the instability ranges. |
2008.06733 | Jun-Jin Peng | Jun-Jin Peng, Chang-Li Zou, Hui-Fa Liu | A Komar-like integral for mass and angular momentum of asymptotically
AdS black holes in Einstein gravity | 27 pages, No figures, minor revision to V1 | Phys. Scr. 96 (2021) 125207 | 10.1088/1402-4896/ac1cd1 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The purpose of this paper is to enhance the conventional Komar integral to
asymptotically anti-de Sitter (AdS) black holes. In order to do so, we first
obtain a potential that is the linear combination of the usual Komar potential
with two third-order derivative terms generated by the action of the
d'Alembertian operator and the exterior derivative upon a Killing vector. Then
this higher-order corrected potential is extended to the Einstein gravity with
a negative cosmological constant, yielding the potential that is the linear
combination of the usual Komar one with it acted on by the d'Alembertian. The
surface integral of the improved Komar potential can serve as a formula for
conserved charges of asymptotically AdS spacetimes. Finally, we make use of
such a formula to compute the mass and the angular momentum of
Schwarzschild-AdS black holes, regular AdS black holes, asymptotically AdS
Kerr-Sen black holes, Kerr-NUT-AdS black holes, and Kerr-AdS black holes in
arbitrary dimensions. The results coincide with the ones in the literature.
| [
{
"created": "Sat, 15 Aug 2020 15:17:36 GMT",
"version": "v1"
},
{
"created": "Tue, 8 Sep 2020 23:31:19 GMT",
"version": "v2"
}
] | 2023-05-24 | [
[
"Peng",
"Jun-Jin",
""
],
[
"Zou",
"Chang-Li",
""
],
[
"Liu",
"Hui-Fa",
""
]
] | The purpose of this paper is to enhance the conventional Komar integral to asymptotically anti-de Sitter (AdS) black holes. In order to do so, we first obtain a potential that is the linear combination of the usual Komar potential with two third-order derivative terms generated by the action of the d'Alembertian operator and the exterior derivative upon a Killing vector. Then this higher-order corrected potential is extended to the Einstein gravity with a negative cosmological constant, yielding the potential that is the linear combination of the usual Komar one with it acted on by the d'Alembertian. The surface integral of the improved Komar potential can serve as a formula for conserved charges of asymptotically AdS spacetimes. Finally, we make use of such a formula to compute the mass and the angular momentum of Schwarzschild-AdS black holes, regular AdS black holes, asymptotically AdS Kerr-Sen black holes, Kerr-NUT-AdS black holes, and Kerr-AdS black holes in arbitrary dimensions. The results coincide with the ones in the literature. |
2407.02046 | Ryuya Kudo | Ryuya Kudo, Hideki Asada | Correspondence between two exact gravitational lens equations in a
static and spherically symmetric spacetime | 7 pages, 9 figures | null | null | null | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | Virbhadra and Ellis have proposed an exact equation (referred to as VE
equation) for the gravitational lens in a static and spherically symmetric
spacetime [Phys. Rev. D 62,084003 (2000)], whereas an improved equation
(referred to as BTOA equation) has been derived by Bozza [Phys. Rev. D 78,
103005 (2008)] and later by Takizawa, Ono and Asada [Phys. Rev. D, 102, 064060
(2020)]. VE and BTOA equations seem to be very different from each other. The
present paper shows that there exists an unphysical branch in VE equation.
Consequently, VE equation can be reduced by removing the unphysical branch. The
reduced version of VE equation is found to be the same as BTOA equation when a
suitable transformation is made between the deflection angles defined
differently in the two formulations. An explicit expression of the
transformation is found. We also argue possible numerical errors when the
transformation between the deflection angles is ignored.
| [
{
"created": "Tue, 2 Jul 2024 08:19:17 GMT",
"version": "v1"
}
] | 2024-07-03 | [
[
"Kudo",
"Ryuya",
""
],
[
"Asada",
"Hideki",
""
]
] | Virbhadra and Ellis have proposed an exact equation (referred to as VE equation) for the gravitational lens in a static and spherically symmetric spacetime [Phys. Rev. D 62,084003 (2000)], whereas an improved equation (referred to as BTOA equation) has been derived by Bozza [Phys. Rev. D 78, 103005 (2008)] and later by Takizawa, Ono and Asada [Phys. Rev. D, 102, 064060 (2020)]. VE and BTOA equations seem to be very different from each other. The present paper shows that there exists an unphysical branch in VE equation. Consequently, VE equation can be reduced by removing the unphysical branch. The reduced version of VE equation is found to be the same as BTOA equation when a suitable transformation is made between the deflection angles defined differently in the two formulations. An explicit expression of the transformation is found. We also argue possible numerical errors when the transformation between the deflection angles is ignored. |
gr-qc/9711073 | Thomas Kloesch | T. Kloesch and T. Strobl | Complete Classification of 1+1 Gravity Solutions | 3 pages, LaTeX, 1 figure, Talk presented at the Eighth Marcel
Grossmann Meeting (MG8), Jerusalem, June 1997 | null | null | TUW-97-18, PITHA 97/41 | gr-qc | null | A classification of the maximally extended solutions for 1+1 gravity models
(comprising e.g. generalized dilaton gravity as well as models with non-trivial
torsion) is presented. No restrictions are placed on the topology of the
arising solutions, and indeed it is found that for generic models solutions on
non-compact surfaces of arbitrary genus with an arbitrary non-zero number of
holes can be obtained. The moduli space of classical solutions (solutions of
the field equations with fixed topology modulo gauge transformations) is
parametrized explicitly.
| [
{
"created": "Tue, 25 Nov 1997 12:01:41 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Kloesch",
"T.",
""
],
[
"Strobl",
"T.",
""
]
] | A classification of the maximally extended solutions for 1+1 gravity models (comprising e.g. generalized dilaton gravity as well as models with non-trivial torsion) is presented. No restrictions are placed on the topology of the arising solutions, and indeed it is found that for generic models solutions on non-compact surfaces of arbitrary genus with an arbitrary non-zero number of holes can be obtained. The moduli space of classical solutions (solutions of the field equations with fixed topology modulo gauge transformations) is parametrized explicitly. |
1402.6252 | Thomas B\"ackdahl | Lars Andersson, Thomas B\"ackdahl and Pieter Blue | Second order symmetry operators | 34 pages. Mathematica notebook available from
http://hdl.handle.net/10283/541 | Class. Quantum Grav. 31 135015 (2014) | 10.1088/0264-9381/31/13/135015 | null | gr-qc math.AP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using systematic calculations in spinor language, we obtain simple
descriptions of the second order symmetry operators for the conformal wave
equation, the Dirac-Weyl equation and the Maxwell equation on a curved four
dimensional Lorentzian manifold. The conditions for existence of symmetry
operators for the different equations are seen to be related. Computer algebra
tools have been developed and used to systematically reduce the equations to a
form which allows geometrical interpretation.
| [
{
"created": "Tue, 25 Feb 2014 17:42:06 GMT",
"version": "v1"
},
{
"created": "Thu, 19 Jun 2014 13:12:40 GMT",
"version": "v2"
}
] | 2014-06-20 | [
[
"Andersson",
"Lars",
""
],
[
"Bäckdahl",
"Thomas",
""
],
[
"Blue",
"Pieter",
""
]
] | Using systematic calculations in spinor language, we obtain simple descriptions of the second order symmetry operators for the conformal wave equation, the Dirac-Weyl equation and the Maxwell equation on a curved four dimensional Lorentzian manifold. The conditions for existence of symmetry operators for the different equations are seen to be related. Computer algebra tools have been developed and used to systematically reduce the equations to a form which allows geometrical interpretation. |
2209.14834 | Reginald Christian Bernardo | Reginald Christian Bernardo and Kin-Wang Ng | Pulsar and cosmic variances of pulsar timing-array correlation
measurements of the stochastic gravitational wave background | 25 pages, 6 figures, minor changes, to appear in JCAP, code in
https://github.com/reggiebernardo/PTAfast | JCAP 11 (2022) 046 | 10.1088/1475-7516/2022/11/046 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Pulsar timing-array correlation measurements offer an exciting opportunity to
test the nature of gravity in the cosmologically novel nanohertz gravitational
wave regime. The stochastic gravitational wave background is assumed Gaussian
and random, while there are limited pulsar pairs in the sky. This brings
theoretical uncertainties to the correlation measurements, namely the pulsar
variance due to pulsar samplings and the cosmic variance due to Gaussian
signals. We demonstrate a straightforward calculation of the mean and the
variances on the Hellings-Downs correlation relying on a power spectrum
formalism. We keep arbitrary pulsar distances and consider gravitational wave
modes beyond Einstein gravity as well as off the light cone throughout, thereby
presenting the most general and, most importantly, numerically efficient
calculation of the variances.
| [
{
"created": "Thu, 29 Sep 2022 14:50:29 GMT",
"version": "v1"
},
{
"created": "Tue, 15 Nov 2022 06:35:37 GMT",
"version": "v2"
}
] | 2022-11-23 | [
[
"Bernardo",
"Reginald Christian",
""
],
[
"Ng",
"Kin-Wang",
""
]
] | Pulsar timing-array correlation measurements offer an exciting opportunity to test the nature of gravity in the cosmologically novel nanohertz gravitational wave regime. The stochastic gravitational wave background is assumed Gaussian and random, while there are limited pulsar pairs in the sky. This brings theoretical uncertainties to the correlation measurements, namely the pulsar variance due to pulsar samplings and the cosmic variance due to Gaussian signals. We demonstrate a straightforward calculation of the mean and the variances on the Hellings-Downs correlation relying on a power spectrum formalism. We keep arbitrary pulsar distances and consider gravitational wave modes beyond Einstein gravity as well as off the light cone throughout, thereby presenting the most general and, most importantly, numerically efficient calculation of the variances. |
gr-qc/9310014 | null | J.E.Nelson | The Constraints of 2+1 Quantum Gravity | 14 pages, plain TEX, no figures, DFTT 53/93 | null | null | null | gr-qc hep-th | null | To appear in proceedings of II Workshop on ``Constraints Theory and
Quantisation Methods''Montepulciano (Siena) 1993}
General discussion of the constraints of 2+1 gravity, with emphasis on two
approaches, namely the second order and first order formalisms, and comparison
with the four dimensional theory wherever possible. Introduction to an operator
algebra approach that has been developed in the last few years in collaboration
with T.Regge, and discussion of the quantisation of the g=1 case.
| [
{
"created": "Thu, 7 Oct 1993 17:30:19 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Nelson",
"J. E.",
""
]
] | To appear in proceedings of II Workshop on ``Constraints Theory and Quantisation Methods''Montepulciano (Siena) 1993} General discussion of the constraints of 2+1 gravity, with emphasis on two approaches, namely the second order and first order formalisms, and comparison with the four dimensional theory wherever possible. Introduction to an operator algebra approach that has been developed in the last few years in collaboration with T.Regge, and discussion of the quantisation of the g=1 case. |
2407.00720 | Hamed Barzegar | Hamed Barzegar and Thomas Buchert | On restrictions of current warp drive spacetimes and immediate
possibilities of improvement | 12 pages, 2 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Looking at current proposals of so-called `warp drive spacetimes', they
appear to employ General Relativity only at an elementary level. A number of
strong restrictions are imposed such as flow-orthogonality of the spacetime
foliation, vanishing spatial Ricci tensor, dimensionally reduced and
coordinate-dependent velocity fields, to mention the main restrictions. We here
provide a brief summary of our proposal of a general and covariant description
of spatial motions within General Relativity, then discuss the restrictions
that are employed in the majority of the current literature. That current warp
drive models are discussed to be unphysical may not be surprising; they lack
important ingredients such as covariantly non-vanishing spatial velocity,
acceleration, vorticity, together with curved space, and a warp mechanism.
| [
{
"created": "Sun, 30 Jun 2024 15:01:23 GMT",
"version": "v1"
}
] | 2024-07-02 | [
[
"Barzegar",
"Hamed",
""
],
[
"Buchert",
"Thomas",
""
]
] | Looking at current proposals of so-called `warp drive spacetimes', they appear to employ General Relativity only at an elementary level. A number of strong restrictions are imposed such as flow-orthogonality of the spacetime foliation, vanishing spatial Ricci tensor, dimensionally reduced and coordinate-dependent velocity fields, to mention the main restrictions. We here provide a brief summary of our proposal of a general and covariant description of spatial motions within General Relativity, then discuss the restrictions that are employed in the majority of the current literature. That current warp drive models are discussed to be unphysical may not be surprising; they lack important ingredients such as covariantly non-vanishing spatial velocity, acceleration, vorticity, together with curved space, and a warp mechanism. |
1308.5772 | Kourosh Nozari | Kourosh Nozari and Narges Rashidi | Cosmological dynamics of a non-minimally coupled bulk scalar field in
DGP setup | 25 pages, Accepted for publication in Astrophyics and Space Science | Astrophys. Space Sci. 349 (2014) 549-559 | 10.1007/s10509-013-1513-3 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider cosmological dynamics of a canonical bulk scalar field, which is
coupled non-minimally to 5-dimensional Ricci scalar in a DGP setup. We show
that presence of this non-minimally coupled bulk scalar field affects the jump
conditions of the original DGP model significantly. Within a superpotential
approach, we perform some numerical analysis of the model parameter space and
consider bulk-brane energy exchange in this setup. Also we show that the
normal, ghost-free branch of the DGP solutions in this case has the potential
to realize a self-consistent phantom-like behavior and therefore explains late
time acceleration of the universe in a consistent way.
| [
{
"created": "Tue, 27 Aug 2013 07:13:40 GMT",
"version": "v1"
}
] | 2015-06-17 | [
[
"Nozari",
"Kourosh",
""
],
[
"Rashidi",
"Narges",
""
]
] | We consider cosmological dynamics of a canonical bulk scalar field, which is coupled non-minimally to 5-dimensional Ricci scalar in a DGP setup. We show that presence of this non-minimally coupled bulk scalar field affects the jump conditions of the original DGP model significantly. Within a superpotential approach, we perform some numerical analysis of the model parameter space and consider bulk-brane energy exchange in this setup. Also we show that the normal, ghost-free branch of the DGP solutions in this case has the potential to realize a self-consistent phantom-like behavior and therefore explains late time acceleration of the universe in a consistent way. |
2011.09842 | Sudip Mishra | Soumya Chakraborty, Sudip Mishra, Subenoy Chakraborty | A Dynamical System Analysis of cosmic evolution with coupled phantom
dark energy with dark matter | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The present work is an example of the application of the dynamical system
analysis in the context of cosmology. Here cosmic evolution is considered in
the background of homogeneous and isotropic flat
Friedmann-Lema\^{i}tre-Robertson-Walker space-time with interacting dark energy
and varying mass dark matter as the matter content. The Dark Energy (DE) is
chosen as phantom scalar field with self-interacting potential while the Dark
Matter (DM) is in the form of dust. The potential of the scalar field and the
mass function of dark matter are chosen as exponential or power-law form or in
their product form. Using suitable dimensionless variables the Einstein field
equations and the conservation equations constitute an autonomous system. The
stability of the non-hyperbolic critical points are analyzed by using center
manifold theory. Finally, cosmological phase transitions have been detected
through bifurcation analysis which has been done by Poincar\'{e} index theory.
| [
{
"created": "Wed, 18 Nov 2020 12:08:52 GMT",
"version": "v1"
}
] | 2020-11-20 | [
[
"Chakraborty",
"Soumya",
""
],
[
"Mishra",
"Sudip",
""
],
[
"Chakraborty",
"Subenoy",
""
]
] | The present work is an example of the application of the dynamical system analysis in the context of cosmology. Here cosmic evolution is considered in the background of homogeneous and isotropic flat Friedmann-Lema\^{i}tre-Robertson-Walker space-time with interacting dark energy and varying mass dark matter as the matter content. The Dark Energy (DE) is chosen as phantom scalar field with self-interacting potential while the Dark Matter (DM) is in the form of dust. The potential of the scalar field and the mass function of dark matter are chosen as exponential or power-law form or in their product form. Using suitable dimensionless variables the Einstein field equations and the conservation equations constitute an autonomous system. The stability of the non-hyperbolic critical points are analyzed by using center manifold theory. Finally, cosmological phase transitions have been detected through bifurcation analysis which has been done by Poincar\'{e} index theory. |
1605.01943 | Ahmed Bouda | T. Foughali and A. Bouda | From Fock's Transformation to de Sitter Space | 8 pages, no figures | Can. J. Phys. 93 (2015) 734 | null | null | gr-qc hep-th math-ph math.MP | http://creativecommons.org/licenses/by/4.0/ | As in Deformed Special Relativity, we showed recently that the Fock
coordinate transformation can be derived from a new deformed Poisson brackets.
This approach allowed us to establish the corresponding momentum transformation
which keeps invariant the four dimensional contraction $p_{\mu} x^{\mu} $. From
the resulting deformed algebra, we construct in this paper the corresponding
first Casimir. After first quantization, we show by using the Klein-Gordon
equation that the spacetime of the Fock transformation is the de Sitter one. As
we will see, the invariant length representing the universe radius in the
spacetime of Fock's transformation is exactly the radius of the embedded
hypersurface representing the de Sitter spacetime.
| [
{
"created": "Fri, 6 May 2016 14:09:41 GMT",
"version": "v1"
}
] | 2016-05-09 | [
[
"Foughali",
"T.",
""
],
[
"Bouda",
"A.",
""
]
] | As in Deformed Special Relativity, we showed recently that the Fock coordinate transformation can be derived from a new deformed Poisson brackets. This approach allowed us to establish the corresponding momentum transformation which keeps invariant the four dimensional contraction $p_{\mu} x^{\mu} $. From the resulting deformed algebra, we construct in this paper the corresponding first Casimir. After first quantization, we show by using the Klein-Gordon equation that the spacetime of the Fock transformation is the de Sitter one. As we will see, the invariant length representing the universe radius in the spacetime of Fock's transformation is exactly the radius of the embedded hypersurface representing the de Sitter spacetime. |
1305.5014 | XiaoXiong Zeng | Yi-Wen Han, Gang Chen, Ming-Jian Lan | Legendre transformations and the thermodynamic geometry of 5D black
holes | 6 pages. arXiv admin note: substantial text overlap with
arXiv:1207.5626; and text overlap with arXiv:0905.1776, arXiv:0811.2524,
arXiv:1104.3723 by other authors | Chinese Physics C 37 (2013) 035101 | 10.1088/1674-1137/37/3/035101 | null | gr-qc | http://creativecommons.org/licenses/by/3.0/ | This paper studies the thermodynamic properties of the 5D black hole in
Einstein-Gauss-Bonnet gravity from the viewpoint of geometrothermodynamics. It
{is found} that the Legendre invariant metrics of the 5D black {holes} in
Einstein-Yang-Mills-Gauss-Bonnet {theory and} Einstein-Maxwell-Gauss-Bonnet
{theory} reproduce the behavior of the thermodynamic interaction and phase
transition structure of the corresponding black hole configurations
{correctly}. It is shown that they are both curved and {that} the curvature
scalar {provides} information about the phase transition point.
| [
{
"created": "Wed, 22 May 2013 03:53:38 GMT",
"version": "v1"
}
] | 2015-06-16 | [
[
"Han",
"Yi-Wen",
""
],
[
"Chen",
"Gang",
""
],
[
"Lan",
"Ming-Jian",
""
]
] | This paper studies the thermodynamic properties of the 5D black hole in Einstein-Gauss-Bonnet gravity from the viewpoint of geometrothermodynamics. It {is found} that the Legendre invariant metrics of the 5D black {holes} in Einstein-Yang-Mills-Gauss-Bonnet {theory and} Einstein-Maxwell-Gauss-Bonnet {theory} reproduce the behavior of the thermodynamic interaction and phase transition structure of the corresponding black hole configurations {correctly}. It is shown that they are both curved and {that} the curvature scalar {provides} information about the phase transition point. |
2008.11033 | Abdul Jawad | Abdul Jawad | Consequences of Thermal Fluctuations of Well-Known Black Holes in
Modified Gravity | 29 pages, 26 figures, Accepted in CQG for publication | null | 10.1088/1361-6382/ab9ad5 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Quantum fluctuation consequences have significant role in high-energy
physics. These fluctuation often regarded as a correction of the infrared (IR)
limit. Such correction contribute to the high-energy limit of thermodynamical
quantities and the stability conditions of black holes. In this work, we
analyze the thermal stability of black holes in the presence of thermal
fluctuations. We consider AdS black hole in Born-Infeld massive gravity with
non-abelian hair and the charged AdS black hole with a global monopole. We
develop many thermodynamical quantities such as entropy, temperature, pressure,
heat capacity of a system at constant volume and pressure, ratio between the
heat capacities at constant pressure and volume, Gibbs free energy and
Helmholtz free energy for both black holes. The critical behavior and phase
transitions of black holes are also presented. We also observe the local and
global stability of black holes in the grand canonical ensemble and canonical
ensemble for the specific values of different parameters, such as, symmetry
breaking parameter $\eta$, massive parameter $m$ and non-abelian hair $\nu$.
| [
{
"created": "Sat, 22 Aug 2020 19:20:27 GMT",
"version": "v1"
}
] | 2020-08-26 | [
[
"Jawad",
"Abdul",
""
]
] | Quantum fluctuation consequences have significant role in high-energy physics. These fluctuation often regarded as a correction of the infrared (IR) limit. Such correction contribute to the high-energy limit of thermodynamical quantities and the stability conditions of black holes. In this work, we analyze the thermal stability of black holes in the presence of thermal fluctuations. We consider AdS black hole in Born-Infeld massive gravity with non-abelian hair and the charged AdS black hole with a global monopole. We develop many thermodynamical quantities such as entropy, temperature, pressure, heat capacity of a system at constant volume and pressure, ratio between the heat capacities at constant pressure and volume, Gibbs free energy and Helmholtz free energy for both black holes. The critical behavior and phase transitions of black holes are also presented. We also observe the local and global stability of black holes in the grand canonical ensemble and canonical ensemble for the specific values of different parameters, such as, symmetry breaking parameter $\eta$, massive parameter $m$ and non-abelian hair $\nu$. |
1611.08909 | Ahmad Borzou | Ahmad Borzou and Behrouz Mirza | A Homogeneous and Isotropic Universe in Lorentz Gauge Theory of Gravity | 14 pages, 4 figures, accepted for publication in CQG | Class. Quantum Grav. 34 (2017) 145005 | 10.1088/1361-6382/aa7647 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Lorentz gauge theory of gravity was recently introduced. We study the
homogeneous and isotropic universe of this theory. It is shown that some time
after the matter in the universe is diluted enough, at $z \sim 0.6$, the
decelerating expansion shifts spontaneously to an accelerating one without a
dark energy. We discuss that Lorentz gauge theory puts no constraint on the
total energy content of the universe at present time and therefore the
magnitude of vacuum energy predicted by field theory is not contradictory
anymore. It is demonstrated that in this theory the limit on the number of
relativistic particles in the universe is much looser than in GR. An
inflationary mechanism is discussed as well. We show that the theory, unlike
GR, does not require the slow-roll or similar conditions to drive the inflation
at the beginning of the universe.
| [
{
"created": "Sun, 27 Nov 2016 20:46:08 GMT",
"version": "v1"
},
{
"created": "Wed, 31 May 2017 23:52:23 GMT",
"version": "v2"
}
] | 2017-07-04 | [
[
"Borzou",
"Ahmad",
""
],
[
"Mirza",
"Behrouz",
""
]
] | Lorentz gauge theory of gravity was recently introduced. We study the homogeneous and isotropic universe of this theory. It is shown that some time after the matter in the universe is diluted enough, at $z \sim 0.6$, the decelerating expansion shifts spontaneously to an accelerating one without a dark energy. We discuss that Lorentz gauge theory puts no constraint on the total energy content of the universe at present time and therefore the magnitude of vacuum energy predicted by field theory is not contradictory anymore. It is demonstrated that in this theory the limit on the number of relativistic particles in the universe is much looser than in GR. An inflationary mechanism is discussed as well. We show that the theory, unlike GR, does not require the slow-roll or similar conditions to drive the inflation at the beginning of the universe. |
gr-qc/9812076 | Claude Barrabes | C. Barrab\`es, V. Frolov and R. Parentani | Metric Fluctuation Corrections to Hawking Radiation | 27 pages, 2 figures, LaTeX. Revised version | Phys.Rev. D59 (1999) 124010 | 10.1103/PhysRevD.59.124010 | null | gr-qc hep-th | null | We study how fluctuations of the black hole geometry affect the properties of
Hawking radiation. Even though we treat the fluctuations classically, we
believe that the results so obtained indicate what might be the effects induced
by quantum fluctuations in a self consistent treatment. To characterize the
fluctuations, we use the model introduced by York in which they are described
by an advanced Vaidya metric with a fluctuating mass. Under the assumption of
spherical symmetry, we solve the equation of null outgoing rays. Then, by
neglecting the greybody factor, we calculate the late time corrections to the
s-wave contributions of the energy flux and the asymptotic spectrum. We find
three kind of modifications. Firstly, the energy flux fluctuates around its
average value with amplitudes and frequencies determined by those of the metric
fluctuations. Secondly, this average value receives two positive contributions
one of which can be reinterpreted as due to the `renormalisation' of the
surface gravity induced by the metric fluctuations. Finally, the asymptotic
spectrum is modified by the addition of terms containing thermal factors in
which the frequency of the metric fluctuations acts as a chemical potential.
| [
{
"created": "Mon, 21 Dec 1998 16:44:19 GMT",
"version": "v1"
},
{
"created": "Tue, 9 Mar 1999 12:53:02 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Barrabès",
"C.",
""
],
[
"Frolov",
"V.",
""
],
[
"Parentani",
"R.",
""
]
] | We study how fluctuations of the black hole geometry affect the properties of Hawking radiation. Even though we treat the fluctuations classically, we believe that the results so obtained indicate what might be the effects induced by quantum fluctuations in a self consistent treatment. To characterize the fluctuations, we use the model introduced by York in which they are described by an advanced Vaidya metric with a fluctuating mass. Under the assumption of spherical symmetry, we solve the equation of null outgoing rays. Then, by neglecting the greybody factor, we calculate the late time corrections to the s-wave contributions of the energy flux and the asymptotic spectrum. We find three kind of modifications. Firstly, the energy flux fluctuates around its average value with amplitudes and frequencies determined by those of the metric fluctuations. Secondly, this average value receives two positive contributions one of which can be reinterpreted as due to the `renormalisation' of the surface gravity induced by the metric fluctuations. Finally, the asymptotic spectrum is modified by the addition of terms containing thermal factors in which the frequency of the metric fluctuations acts as a chemical potential. |
1912.03882 | Emmanuil Saridakis | Emmanuel N. Saridakis, Shynaray Myrzakul, Kairat Myrzakulov, Koblandy
Yerzhanov | Cosmological applications of Myrzakulov gravity | 10 pages, 4 figures, version published in Phys.Rev.D | Phys. Rev. D 102, 023525 (2020) | 10.1103/PhysRevD.102.023525 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the cosmological applications of Myrzakulov $F(R,T)$ gravity.
In this theory ones uses a specific but non-special connection, and thus both
curvature and torsion are dynamical fields related to gravity. We introduce a
parametrization that quantifies the deviation of curvature and torsion scalars
form their corresponding values obtained using the special Levi-Civita and
Weitzenb{\"{o}}ck connections, and we extract the cosmological field equations
following the mini-super-space procedure. Even for the simple case where the
action of the theory is linear in $R$ and $T$, we find that the Friedmann
equations contain new terms of geometrical origin, reflecting the non-special
connection. Applying the theory at late times we find that we can acquire the
thermal history of the universe, where dark energy can be quintessence-like or
phantom-like, or behave exactly as a cosmological constant and thus reproducing
$\Lambda$CDM cosmology. Furthermore, we show that these features are obtained
for other Lagrangian choices, too. Finally, early-time application leads to the
de Sitter solution, as well as to an inflationary realization with the desired
scale-factor evolution.
| [
{
"created": "Mon, 9 Dec 2019 07:33:38 GMT",
"version": "v1"
},
{
"created": "Sat, 7 Nov 2020 08:49:36 GMT",
"version": "v2"
}
] | 2020-11-10 | [
[
"Saridakis",
"Emmanuel N.",
""
],
[
"Myrzakul",
"Shynaray",
""
],
[
"Myrzakulov",
"Kairat",
""
],
[
"Yerzhanov",
"Koblandy",
""
]
] | We investigate the cosmological applications of Myrzakulov $F(R,T)$ gravity. In this theory ones uses a specific but non-special connection, and thus both curvature and torsion are dynamical fields related to gravity. We introduce a parametrization that quantifies the deviation of curvature and torsion scalars form their corresponding values obtained using the special Levi-Civita and Weitzenb{\"{o}}ck connections, and we extract the cosmological field equations following the mini-super-space procedure. Even for the simple case where the action of the theory is linear in $R$ and $T$, we find that the Friedmann equations contain new terms of geometrical origin, reflecting the non-special connection. Applying the theory at late times we find that we can acquire the thermal history of the universe, where dark energy can be quintessence-like or phantom-like, or behave exactly as a cosmological constant and thus reproducing $\Lambda$CDM cosmology. Furthermore, we show that these features are obtained for other Lagrangian choices, too. Finally, early-time application leads to the de Sitter solution, as well as to an inflationary realization with the desired scale-factor evolution. |
1903.08399 | Tsutomu Kobayashi | Shin'ichi Hirano, Tsutomu Kobayashi, Daisuke Yamauchi | On the screening mechanism in DHOST theories evading gravitational wave
constraints | 6 pages, 2 figures | Phys. Rev. D 99, 104073 (2019) | 10.1103/PhysRevD.99.104073 | RUP-19-8 | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider a subclass of degenerate higher-order scalar-tensor (DHOST)
theories in which gravitational waves propagate at the speed of light and do
not decay into scalar fluctuations. The screening mechanism in DHOST theories
evading these two gravitational wave constraints operates very differently from
that in generic DHOST theories. We derive a spherically symmetric solution in
the presence of nonrelativistic matter. General relativity is recovered in the
vacuum exterior region provided that functions in the Lagrangian satisfy a
certain condition, implying that fine-tuning is required. Gravity in the matter
interior exhibits novel features: although the gravitational potentials still
obey the standard inverse power law, the effective gravitational constant is
different from its exterior value, and the two metric potentials do not
coincide. We discuss possible observational constraints on this subclass of
DHOST theories, and argue that the tightest bound comes from the Hulse-Taylor
pulsar.
| [
{
"created": "Wed, 20 Mar 2019 09:21:14 GMT",
"version": "v1"
}
] | 2019-06-05 | [
[
"Hirano",
"Shin'ichi",
""
],
[
"Kobayashi",
"Tsutomu",
""
],
[
"Yamauchi",
"Daisuke",
""
]
] | We consider a subclass of degenerate higher-order scalar-tensor (DHOST) theories in which gravitational waves propagate at the speed of light and do not decay into scalar fluctuations. The screening mechanism in DHOST theories evading these two gravitational wave constraints operates very differently from that in generic DHOST theories. We derive a spherically symmetric solution in the presence of nonrelativistic matter. General relativity is recovered in the vacuum exterior region provided that functions in the Lagrangian satisfy a certain condition, implying that fine-tuning is required. Gravity in the matter interior exhibits novel features: although the gravitational potentials still obey the standard inverse power law, the effective gravitational constant is different from its exterior value, and the two metric potentials do not coincide. We discuss possible observational constraints on this subclass of DHOST theories, and argue that the tightest bound comes from the Hulse-Taylor pulsar. |
1904.02744 | Neil J. Cornish | Logan O'Beirne, Neil J. Cornish, Sarah J. Vigeland, Stephen R. Taylor | Constraining alternative polarization states of gravitational waves from
individual black hole binaries using pulsar timing arrays | 12 pages, 8 figures | Phys. Rev. D 99, 124039 (2019) | 10.1103/PhysRevD.99.124039 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Pulsar timing arrays are sensitive to gravitational wave perturbations
produced by individual supermassive black hole binaries during their early
inspiral phase. Modified gravity theories allow for the emission of
gravitational dipole radiation, which is enhanced relative to the quadrupole
contribution for low orbital velocities, making the early inspiral an ideal
regime to test for the presence of modified gravity effects. Using a
theory-agnostic description of modified gravity theories based on the
parametrized post-Einsteinian framework, we explore the possibility of
detecting deviations from General Relativity using simulated pulsar timing
array data, and provide forecasts for the constraints that can be achieved. We
generalize the {\tt enterprise} pulsar timing software to account for possible
additional polarization states and modifications to the phase evolution, and
study how accurately the parameters of simulated signals can be recovered. We
find that while a pure dipole model can partially recover a pure quadrupole
signal, there is little possibility for confusion when the full model with all
polarization states is used. With no signal present, and using noise levels
comparable to those seen in contemporary arrays, we produce forecasts for the
upper limits that can be placed on the amplitudes of alternative polarization
modes as a function of the sky location of the source.
| [
{
"created": "Thu, 4 Apr 2019 18:45:03 GMT",
"version": "v1"
}
] | 2019-07-03 | [
[
"O'Beirne",
"Logan",
""
],
[
"Cornish",
"Neil J.",
""
],
[
"Vigeland",
"Sarah J.",
""
],
[
"Taylor",
"Stephen R.",
""
]
] | Pulsar timing arrays are sensitive to gravitational wave perturbations produced by individual supermassive black hole binaries during their early inspiral phase. Modified gravity theories allow for the emission of gravitational dipole radiation, which is enhanced relative to the quadrupole contribution for low orbital velocities, making the early inspiral an ideal regime to test for the presence of modified gravity effects. Using a theory-agnostic description of modified gravity theories based on the parametrized post-Einsteinian framework, we explore the possibility of detecting deviations from General Relativity using simulated pulsar timing array data, and provide forecasts for the constraints that can be achieved. We generalize the {\tt enterprise} pulsar timing software to account for possible additional polarization states and modifications to the phase evolution, and study how accurately the parameters of simulated signals can be recovered. We find that while a pure dipole model can partially recover a pure quadrupole signal, there is little possibility for confusion when the full model with all polarization states is used. With no signal present, and using noise levels comparable to those seen in contemporary arrays, we produce forecasts for the upper limits that can be placed on the amplitudes of alternative polarization modes as a function of the sky location of the source. |
2111.04557 | Pisin Chen | Pisin Chen | Gravitational Synchrotron Radiation from Storage Rings | 5 pages, 2 figures | null | null | null | gr-qc hep-ex physics.acc-ph | http://creativecommons.org/publicdomain/zero/1.0/ | We reinvestigate the gravitational waves (GWs) induced by charged particles
in storage rings. There are two major components in such GWs. One is the
gravitational synchrotron radiation (GSR), i.e., the direct emission by the
bending of the trajectory of a relativistic charged particle, much like the
conventional electromagnetic synchrotron radiation (EMSR), albeit with
characteristic difference in their radiation spectra. While the conventional
EMSR spectrum peaks at the critical frequency,
$\omega_c=\gamma^3\omega_0\gg\omega_0$, the spectrum of GSR peaks at the
storage ring fundamental frequency $\omega_0$, which is much lower. The other
is the resonant conversion of EMSR to GWs at the same frequency through the
storage ring bending magnets, i.e., the Gertsenshtein effect. Invoking LHC at
CERN as a numerical example, we found that the spacetime perturbation
associated with GSR, $h\sim 5\times 10^{-40}$, falls far below the sensitivity
of GW detectors based on the LIGO-type Michelson interferometry approach. On
the other hand, the GWs induced by the resonant conversion of EMSR have much
higher frequencies and thus much localized, so it is conceivable to detect them
through the reverse conversion, the so-called `light shining through a wall',
process.
| [
{
"created": "Mon, 8 Nov 2021 15:13:10 GMT",
"version": "v1"
},
{
"created": "Wed, 24 Nov 2021 09:44:53 GMT",
"version": "v2"
}
] | 2021-11-25 | [
[
"Chen",
"Pisin",
""
]
] | We reinvestigate the gravitational waves (GWs) induced by charged particles in storage rings. There are two major components in such GWs. One is the gravitational synchrotron radiation (GSR), i.e., the direct emission by the bending of the trajectory of a relativistic charged particle, much like the conventional electromagnetic synchrotron radiation (EMSR), albeit with characteristic difference in their radiation spectra. While the conventional EMSR spectrum peaks at the critical frequency, $\omega_c=\gamma^3\omega_0\gg\omega_0$, the spectrum of GSR peaks at the storage ring fundamental frequency $\omega_0$, which is much lower. The other is the resonant conversion of EMSR to GWs at the same frequency through the storage ring bending magnets, i.e., the Gertsenshtein effect. Invoking LHC at CERN as a numerical example, we found that the spacetime perturbation associated with GSR, $h\sim 5\times 10^{-40}$, falls far below the sensitivity of GW detectors based on the LIGO-type Michelson interferometry approach. On the other hand, the GWs induced by the resonant conversion of EMSR have much higher frequencies and thus much localized, so it is conceivable to detect them through the reverse conversion, the so-called `light shining through a wall', process. |
1306.4392 | Franco Fiorini | Franco Fiorini | Nonsingular Promises from Born-Infeld Gravity | 5 pages, no figures. Accepted for publication in Physical Review
Letters | Phys. Rev. Lett. 111 (2013) 041104 | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Born-Infeld determinantal gravity formulated in Weitzenbock spacetime is
discussed in the context of Friedmann-Robertson-Walker (FRW) cosmologies. It is
shown how the standard model big bang singularity is absent in certain
spatially flat FRW spacetimes, where the high energy regime is characterized by
a de Sitter inflationary stage of geometrical character, i.e., without the
presence of the inflaton field. This taming of the initial singularity is also
achieved for some spatially curved FRW manifolds where the singularity is
replaced by a de Sitter stage or a big bounce of the scale factor depending on
certain combinations of free parameters appearing in the action. Unlike other
Born-Infeld-like theories in vogue, the one here presented is also capable of
deforming vacuum general relativistic solutions.
| [
{
"created": "Tue, 18 Jun 2013 23:27:51 GMT",
"version": "v1"
},
{
"created": "Tue, 16 Jul 2013 22:12:06 GMT",
"version": "v2"
}
] | 2013-07-24 | [
[
"Fiorini",
"Franco",
""
]
] | Born-Infeld determinantal gravity formulated in Weitzenbock spacetime is discussed in the context of Friedmann-Robertson-Walker (FRW) cosmologies. It is shown how the standard model big bang singularity is absent in certain spatially flat FRW spacetimes, where the high energy regime is characterized by a de Sitter inflationary stage of geometrical character, i.e., without the presence of the inflaton field. This taming of the initial singularity is also achieved for some spatially curved FRW manifolds where the singularity is replaced by a de Sitter stage or a big bounce of the scale factor depending on certain combinations of free parameters appearing in the action. Unlike other Born-Infeld-like theories in vogue, the one here presented is also capable of deforming vacuum general relativistic solutions. |
gr-qc/0401069 | Tiberiu Harko | T. Harko, M. K. Mak | Anisotropy in Bianchi-type brane cosmologies | 12 pages, no figures, to appear in Class. Quantum Grav | Class.Quant.Grav. 21 (2004) 1489-1504 | 10.1088/0264-9381/21/6/015 | null | gr-qc hep-th | null | The behavior near the initial singular state of the anisotropy parameter of
the arbitrary type, homogeneous and anisotropic Bianchi models is considered in
the framework of the brane world cosmological models. The matter content on the
brane is assumed to be an isotropic perfect cosmological fluid, obeying a
barotropic equation of state. To obtain the value of the anisotropy parameter
at an arbitrary moment an evolution equation is derived, describing the
dynamics of the anisotropy as a function of the volume scale factor of the
Universe. The general solution of this equation can be obtained in an exact
analytical form for the Bianchi I and V types and in a closed form for all
other homogeneous and anisotropic geometries. The study of the values of the
anisotropy in the limit of small times shows that for all Bianchi type
space-times filled with a non-zero pressure cosmological fluid, obeying a
linear barotropic equation of state, the initial singular state on the brane is
isotropic. This result is obtained by assuming that in the limit of small times
the asymptotic behavior of the scale factors is of Kasner-type. For brane
worlds filled with dust, the initial values of the anisotropy coincide in both
brane world and standard four-dimensional general relativistic cosmologies.
| [
{
"created": "Fri, 16 Jan 2004 05:08:30 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Harko",
"T.",
""
],
[
"Mak",
"M. K.",
""
]
] | The behavior near the initial singular state of the anisotropy parameter of the arbitrary type, homogeneous and anisotropic Bianchi models is considered in the framework of the brane world cosmological models. The matter content on the brane is assumed to be an isotropic perfect cosmological fluid, obeying a barotropic equation of state. To obtain the value of the anisotropy parameter at an arbitrary moment an evolution equation is derived, describing the dynamics of the anisotropy as a function of the volume scale factor of the Universe. The general solution of this equation can be obtained in an exact analytical form for the Bianchi I and V types and in a closed form for all other homogeneous and anisotropic geometries. The study of the values of the anisotropy in the limit of small times shows that for all Bianchi type space-times filled with a non-zero pressure cosmological fluid, obeying a linear barotropic equation of state, the initial singular state on the brane is isotropic. This result is obtained by assuming that in the limit of small times the asymptotic behavior of the scale factors is of Kasner-type. For brane worlds filled with dust, the initial values of the anisotropy coincide in both brane world and standard four-dimensional general relativistic cosmologies. |
1701.05669 | Zhongheng Li | Shanshan Li, Dan-Dan Li, Li-Qin Mi, Zhong-Heng Li | Parametric Solution of a Small-Large Black Hole Coexistence Curve | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the first-order phase transition of a charged anti-de Sitter
black hole, and find that the equation of state with the conditions of the two
coexisting phases, leads to the two coupled equations about the thermodynamic
volumes of small black hole and large black hole. By solving the equations, it
is found that each reduced volume is only a function of the parameter $\omega$
. All properties of the coexistence curve can be studied from the two volume
functions. In particular, each thermodynamic quantity is described by a
piecewise analytic function. The demarcation point is located at
$\omega_{d}=12(2\sqrt{3}-3)$. The thermodynamic function but not its
derivative, is continuous at the point. This property is completely different
from that of the ven der Waals fluid. Moreover, the thermodynamic behaviors as
$\omega\rightarrow0$ are discussed. From which one can easily obtain some
critical exponents and amplitudes for small-large black hole phase transitions.
| [
{
"created": "Fri, 20 Jan 2017 03:34:21 GMT",
"version": "v1"
}
] | 2017-01-23 | [
[
"Li",
"Shanshan",
""
],
[
"Li",
"Dan-Dan",
""
],
[
"Mi",
"Li-Qin",
""
],
[
"Li",
"Zhong-Heng",
""
]
] | We consider the first-order phase transition of a charged anti-de Sitter black hole, and find that the equation of state with the conditions of the two coexisting phases, leads to the two coupled equations about the thermodynamic volumes of small black hole and large black hole. By solving the equations, it is found that each reduced volume is only a function of the parameter $\omega$ . All properties of the coexistence curve can be studied from the two volume functions. In particular, each thermodynamic quantity is described by a piecewise analytic function. The demarcation point is located at $\omega_{d}=12(2\sqrt{3}-3)$. The thermodynamic function but not its derivative, is continuous at the point. This property is completely different from that of the ven der Waals fluid. Moreover, the thermodynamic behaviors as $\omega\rightarrow0$ are discussed. From which one can easily obtain some critical exponents and amplitudes for small-large black hole phase transitions. |
1205.3403 | Alessandro Nagar | Sebastiano Bernuzzi, Alessandro Nagar, Marcus Thierfelder and Bernd
Bruegmann | Tidal effects in binary neutron star coalescence | 12 pages, 8 figures, submitted to Phys. Rev. D | Phys. Rev. D 86, 044030 (2012) | 10.1103/PhysRevD.86.044030 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We compare dynamics and waveforms from binary neutron star coalescence as
computed by new long-term ($\sim 10 $ orbits) numerical relativity simulations
and by the tidal effective-one-body (EOB) model including analytical tidal
corrections up to second post-Newtonian order (2PN). The current analytical
knowledge encoded in the tidal EOB model is found to be sufficient to reproduce
the numerical data up to contact and within their uncertainties. Remarkably, no
calibration of any tidal EOB free parameters is required, beside those already
fitted to binary black holes data. The inclusion of 2PN tidal corrections
minimizes the differences with the numerical data, but it is not possible to
significantly distinguish them from the leading-order tidal contribution. The
presence of a relevant amplification of tidal effects is likely to be excluded,
although it can appear as a consequence of numerical inaccuracies. We conclude
that the tidally-completed effective-one-body model provides nowadays the most
advanced and accurate tool for modelling gravitational waveforms from binary
neutron star inspiral up to contact. This work also points out the importance
of extensive tests to assess the uncertainties of the numerical data, and the
potential need of new numerical strategies to perform accurate simulations.
| [
{
"created": "Tue, 15 May 2012 15:02:18 GMT",
"version": "v1"
}
] | 2013-04-25 | [
[
"Bernuzzi",
"Sebastiano",
""
],
[
"Nagar",
"Alessandro",
""
],
[
"Thierfelder",
"Marcus",
""
],
[
"Bruegmann",
"Bernd",
""
]
] | We compare dynamics and waveforms from binary neutron star coalescence as computed by new long-term ($\sim 10 $ orbits) numerical relativity simulations and by the tidal effective-one-body (EOB) model including analytical tidal corrections up to second post-Newtonian order (2PN). The current analytical knowledge encoded in the tidal EOB model is found to be sufficient to reproduce the numerical data up to contact and within their uncertainties. Remarkably, no calibration of any tidal EOB free parameters is required, beside those already fitted to binary black holes data. The inclusion of 2PN tidal corrections minimizes the differences with the numerical data, but it is not possible to significantly distinguish them from the leading-order tidal contribution. The presence of a relevant amplification of tidal effects is likely to be excluded, although it can appear as a consequence of numerical inaccuracies. We conclude that the tidally-completed effective-one-body model provides nowadays the most advanced and accurate tool for modelling gravitational waveforms from binary neutron star inspiral up to contact. This work also points out the importance of extensive tests to assess the uncertainties of the numerical data, and the potential need of new numerical strategies to perform accurate simulations. |
2303.03835 | Mokdad Mokdad | Mokdad Mokdad and Milos Provci | Scattering of Dirac Fields in the Interior of Kerr-Newman(-Anti)-de
Sitter Black Holes | 38 pages | null | null | null | gr-qc math-ph math.AP math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we construct a scattering theory for the massive and charged
Dirac fields in the interiors of sub-extremal Kerr-Newman-(anti)-de Sitter
black holes. More precisely, we show existence, uniqueness and asymptotic
completeness of scattering data for such Dirac fields from the event horizon of
the black hole to the Cauchy horizon. Our approach relies on constructing the
wave operators where the Hamiltonian of the full dynamics is time-dependent.
| [
{
"created": "Tue, 7 Mar 2023 12:03:48 GMT",
"version": "v1"
}
] | 2023-03-08 | [
[
"Mokdad",
"Mokdad",
""
],
[
"Provci",
"Milos",
""
]
] | In this paper we construct a scattering theory for the massive and charged Dirac fields in the interiors of sub-extremal Kerr-Newman-(anti)-de Sitter black holes. More precisely, we show existence, uniqueness and asymptotic completeness of scattering data for such Dirac fields from the event horizon of the black hole to the Cauchy horizon. Our approach relies on constructing the wave operators where the Hamiltonian of the full dynamics is time-dependent. |
1506.08457 | Alessandro Nagar | Alessandro Nagar, Thibault Damour, Christian Reisswig, and Denis
Pollney | Energetics and phasing of nonprecessing spinning coalescing black hole
binaries | 26 pages, 27 figures, results improved with respect to first version | Phys. Rev. D 93, 044046 (2016) | 10.1103/PhysRevD.93.044046 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present an improved numerical relativity (NR) calibration of the new
effective-one-body (EOB) model for coalescing non precessing spinning black
hole binaries recently introduced by Damour and Nagar [Physical Review D 90,
044018 (2014)]. We do so by comparing the EOB predictions to both the phasing
and the energetics provided by two independent sets of NR data covering mass
ratios $1\leq q \leq 9.989$ and dimensionless spin range $-0.95\leq \chi\leq
+0.994$. One set of data is a subset of the Simulating eXtreme Spacetimes (SXS)
catalog of public waveforms; the other set consists of new simulations obtained
with the Llama code plus Cauchy Characteristic Evolution. We present the first
systematic computation of the gauge-invariant relation between the binding
energy and the total angular momentum, $E_{b}(j)$, for a large sample of,
spin-aligned, SXS and Llama data. The dynamics of the EOB model presented here
involves only two free functional parameters, one ($a_6^c(\nu)$) entering the
non spinning sector, as a 5PN effective correction to the interaction
potential, and one ($c_3(\tilde{a}_1,\tilde{a}_2,\nu))$ in the spinning sector,
as an effective next-to-next-to-next-to-leading order correction to the
spin-orbit coupling. These parameters are determined (together with a third
functional parameter $\Delta t_{\rm NQC}(\chi)$ entering the waveform) by
comparing the EOB phasing with the SXS phasing, the consistency of the
energetics being checked afterwards. The quality of the analytical model for
gravitational wave data analysis purposes is assessed by computing the EOB/NR
faithfulness. Over the NR data sample and when varying the total mass between
20 and 200~$M_\odot$ the EOB/NR unfaithfulness (integrated over the NR
frequency range) is found to vary between $99.493\%$ and $99.984\%$ with a
median value of $99.944\%$.
| [
{
"created": "Sun, 28 Jun 2015 21:49:15 GMT",
"version": "v1"
},
{
"created": "Fri, 27 Nov 2015 14:52:06 GMT",
"version": "v2"
}
] | 2016-02-24 | [
[
"Nagar",
"Alessandro",
""
],
[
"Damour",
"Thibault",
""
],
[
"Reisswig",
"Christian",
""
],
[
"Pollney",
"Denis",
""
]
] | We present an improved numerical relativity (NR) calibration of the new effective-one-body (EOB) model for coalescing non precessing spinning black hole binaries recently introduced by Damour and Nagar [Physical Review D 90, 044018 (2014)]. We do so by comparing the EOB predictions to both the phasing and the energetics provided by two independent sets of NR data covering mass ratios $1\leq q \leq 9.989$ and dimensionless spin range $-0.95\leq \chi\leq +0.994$. One set of data is a subset of the Simulating eXtreme Spacetimes (SXS) catalog of public waveforms; the other set consists of new simulations obtained with the Llama code plus Cauchy Characteristic Evolution. We present the first systematic computation of the gauge-invariant relation between the binding energy and the total angular momentum, $E_{b}(j)$, for a large sample of, spin-aligned, SXS and Llama data. The dynamics of the EOB model presented here involves only two free functional parameters, one ($a_6^c(\nu)$) entering the non spinning sector, as a 5PN effective correction to the interaction potential, and one ($c_3(\tilde{a}_1,\tilde{a}_2,\nu))$ in the spinning sector, as an effective next-to-next-to-next-to-leading order correction to the spin-orbit coupling. These parameters are determined (together with a third functional parameter $\Delta t_{\rm NQC}(\chi)$ entering the waveform) by comparing the EOB phasing with the SXS phasing, the consistency of the energetics being checked afterwards. The quality of the analytical model for gravitational wave data analysis purposes is assessed by computing the EOB/NR faithfulness. Over the NR data sample and when varying the total mass between 20 and 200~$M_\odot$ the EOB/NR unfaithfulness (integrated over the NR frequency range) is found to vary between $99.493\%$ and $99.984\%$ with a median value of $99.944\%$. |
1806.07672 | Gen Ye | Gen Ye and Yun-Song Piao | Quantum decoherence of primordial perturbations through nonlinear
scaler-tensor interaction | 23 pages, 3 figures | null | null | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Scaler and tensor perturbations couple nonlinearly with each other in the
Einstein-Hilbert action. We show that such interaction naturally leads to the
quantum decoherence of the primordial perturbations during inflation at horizon
crossing. The dominant interaction Hamiltonian contributing to decoherence is
identified and the master equation responsible for the decohering process is
derived.
| [
{
"created": "Wed, 20 Jun 2018 11:39:45 GMT",
"version": "v1"
}
] | 2018-06-21 | [
[
"Ye",
"Gen",
""
],
[
"Piao",
"Yun-Song",
""
]
] | Scaler and tensor perturbations couple nonlinearly with each other in the Einstein-Hilbert action. We show that such interaction naturally leads to the quantum decoherence of the primordial perturbations during inflation at horizon crossing. The dominant interaction Hamiltonian contributing to decoherence is identified and the master equation responsible for the decohering process is derived. |
1504.00333 | Andre Fuzfa | A. F\"uzfa | How current loops and solenoids curve space-time | 12 pages, 8 figures, accepted for publication in PRD | Phys. Rev. D 93, 024014 (2016) | 10.1103/PhysRevD.93.024014 | null | gr-qc cond-mat.supr-con hep-ex | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The curved space-time around current loops and solenoids carrying arbitrarily
large steady electric currents is obtained from the numerical resolution of the
coupled Einstein-Maxwell equations in cylindrical symmetry. The artificial
gravitational field associated to the generation of a magnetic field produces
gravitational redshift of photons and deviation of light. Null geodesics in the
curved space-time of current loops and solenoids are also presented. We finally
propose an experimental setup, achievable with current technology of
superconducting coils, that produces a phase shift of light of the same order
of magnitude than astrophysical signals in ground-based gravitational wave
observatories.
| [
{
"created": "Wed, 1 Apr 2015 18:39:23 GMT",
"version": "v1"
},
{
"created": "Thu, 26 Nov 2015 09:23:21 GMT",
"version": "v2"
},
{
"created": "Mon, 14 Dec 2015 11:23:35 GMT",
"version": "v3"
}
] | 2016-01-19 | [
[
"Füzfa",
"A.",
""
]
] | The curved space-time around current loops and solenoids carrying arbitrarily large steady electric currents is obtained from the numerical resolution of the coupled Einstein-Maxwell equations in cylindrical symmetry. The artificial gravitational field associated to the generation of a magnetic field produces gravitational redshift of photons and deviation of light. Null geodesics in the curved space-time of current loops and solenoids are also presented. We finally propose an experimental setup, achievable with current technology of superconducting coils, that produces a phase shift of light of the same order of magnitude than astrophysical signals in ground-based gravitational wave observatories. |
1702.00189 | Ghadir Jafari | Ghadir Jafari, M. R. Setare, Hamid R. Bakhtiarizadeh | Static spherically symmetric black holes in de Rham-Gabadadze-Tolley
massive gravity in arbitrary dimensions | Version accepted for publication in PLB | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This article is devoted to static spherically symmetric black hole solutions
of dRGT (de Rham-Gabadadze-Tolley) massive gravity in the presence of
cosmological constant. The unitary and non-unitary gauges are used to find the
solutions in three, four and five dimensions. We show that there are two
general classes of solutions. In one of them, the effect of massive potential
is appeared as the effective cosmological constant. By investigating these
solutions in different dimensions, we find an expression for effective
cosmological constant in arbitrary dimensions.
| [
{
"created": "Wed, 1 Feb 2017 10:18:23 GMT",
"version": "v1"
},
{
"created": "Fri, 1 Sep 2017 17:01:11 GMT",
"version": "v2"
}
] | 2017-09-04 | [
[
"Jafari",
"Ghadir",
""
],
[
"Setare",
"M. R.",
""
],
[
"Bakhtiarizadeh",
"Hamid R.",
""
]
] | This article is devoted to static spherically symmetric black hole solutions of dRGT (de Rham-Gabadadze-Tolley) massive gravity in the presence of cosmological constant. The unitary and non-unitary gauges are used to find the solutions in three, four and five dimensions. We show that there are two general classes of solutions. In one of them, the effect of massive potential is appeared as the effective cosmological constant. By investigating these solutions in different dimensions, we find an expression for effective cosmological constant in arbitrary dimensions. |
gr-qc/0211102 | Ujjal Debnath | Ujjal Debnath and Subenoy Chakraborty | Gravitational Collapse in Higher Dimension | 8 Latex pages, No figure, Revtex style | Gen.Rel.Grav. 36 (2004) 1243-1253 | 10.1023/B:GERG.0000022385.32666.4d | null | gr-qc | null | Spherically symmetric inhomogeneous dust collapse has been studied in higher
dimensional space-time and appearance of naked singularity has been analyzed
both for non-marginal and marginally bound cases. It has been shown that naked
singularity is possible for any arbitrary dimension in non-marginally bound
case. For marginally bound case we have examined the radial null geodesics from
the singularity and found that naked singularity is possible upto five
dimension.
| [
{
"created": "Fri, 29 Nov 2002 04:10:43 GMT",
"version": "v1"
},
{
"created": "Mon, 3 Mar 2003 10:35:51 GMT",
"version": "v2"
}
] | 2009-11-07 | [
[
"Debnath",
"Ujjal",
""
],
[
"Chakraborty",
"Subenoy",
""
]
] | Spherically symmetric inhomogeneous dust collapse has been studied in higher dimensional space-time and appearance of naked singularity has been analyzed both for non-marginal and marginally bound cases. It has been shown that naked singularity is possible for any arbitrary dimension in non-marginally bound case. For marginally bound case we have examined the radial null geodesics from the singularity and found that naked singularity is possible upto five dimension. |
1105.6156 | Chen Songbai | Weiping Yao, Songbai Chen, Changqing Liu, Jiliang Jing | Effects of acceleration on the collision of particles in the rotating
black hole spacetime | 7 pages, 2 figures, The corrected version accepted for publication in
EPJC | Eur. Phys. J. C (2012) 72:1898 | 10.1140/epjc/s10052-012-1898-0 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the collision of two geodesic particles in the accelerating and
rotating black hole spacetime and probe the effects of the acceleration of
black hole on the center-of-mass energy of the colliding particles and on the
high-velocity collision belts. We find that the dependence of the
center-of-mass energy on the acceleration in the near event-horizon collision
is different from that in the near acceleration-horizon case. Moreover, the
presence of the acceleration changes the shape and position of the
high-velocity collision belts. Our results show that the acceleration of black
holes brings richer physics for the collision of particles.
| [
{
"created": "Tue, 31 May 2011 03:37:46 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Feb 2012 04:45:32 GMT",
"version": "v2"
}
] | 2015-05-28 | [
[
"Yao",
"Weiping",
""
],
[
"Chen",
"Songbai",
""
],
[
"Liu",
"Changqing",
""
],
[
"Jing",
"Jiliang",
""
]
] | We study the collision of two geodesic particles in the accelerating and rotating black hole spacetime and probe the effects of the acceleration of black hole on the center-of-mass energy of the colliding particles and on the high-velocity collision belts. We find that the dependence of the center-of-mass energy on the acceleration in the near event-horizon collision is different from that in the near acceleration-horizon case. Moreover, the presence of the acceleration changes the shape and position of the high-velocity collision belts. Our results show that the acceleration of black holes brings richer physics for the collision of particles. |
2401.16949 | Florian Steininger | Hamed Barzegar, Piotr T. Chru\'sciel, Florian Steininger | On elastic deformations of cylindrical bodies under the influence of the
gravitational field | 31 pages, 21 figures | null | null | UWThPh-2024-3 | gr-qc physics.class-ph quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyse the deformations of a cylindrical elastic body resulting from
displacements in a varying gravitational field.
| [
{
"created": "Tue, 30 Jan 2024 12:21:12 GMT",
"version": "v1"
}
] | 2024-01-31 | [
[
"Barzegar",
"Hamed",
""
],
[
"Chruściel",
"Piotr T.",
""
],
[
"Steininger",
"Florian",
""
]
] | We analyse the deformations of a cylindrical elastic body resulting from displacements in a varying gravitational field. |
2301.13751 | Bayram Tekin | Aydin Tavlayan and Bayram Tekin | Instability of a Kerr-type naked singularity due to light and matter
accretion and its shadow | 26 pages, discussions extended, matches the published version | Class. Quantum Grav. 41 065004 (2024) | 10.1088/1361-6382/ad2318 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study null and timelike constant radii geodesics in the environment of an
over-spinning putative Kerr-type naked singularity. We are particularly
interested in two topics: first, the differences of the shadows of the naked
rotating singularity and the Kerr black hole; and second, the spinning down
effect of the particles falling from the accretion disk. Around the naked
singularity, the non-equatorial prograde orbits in the Kerr black hole remain
intact up to a critical rotation parameter ($\alpha=\sqrt{6 \sqrt{3}-9}$) and
cease to exist above this value [Eur. Phys. J. C 78, 879 (2018)]. This has an
important consequence in the shadow of the naked singularity if the shadow is
registered by an observer on the polar plane or close to it as the shadow
cannot be distinguished from that of a Kerr black hole viewed from the same
angle considering only the light emanating from the unstable photon orbits. We
show that the timelike retrograde orbits in the equatorial plane immediately
(after about an 8% increase in mass for the case of initial $\alpha=1.5$)
reduce the spin parameter of the naked singularity from larger values to
$\alpha=1$ at which an event horizon appears. This happens because the
retrograde orbits have a larger capture cross-section than the prograde ones.
So if a naked singularity happens to have an accretion disk, it will not remain
naked for long, an event horizon forms.
| [
{
"created": "Tue, 31 Jan 2023 16:38:42 GMT",
"version": "v1"
},
{
"created": "Thu, 9 Feb 2023 12:33:20 GMT",
"version": "v2"
},
{
"created": "Mon, 18 Sep 2023 05:52:43 GMT",
"version": "v3"
},
{
"created": "Mon, 19 Feb 2024 13:19:26 GMT",
"version": "v4"
}
] | 2024-02-20 | [
[
"Tavlayan",
"Aydin",
""
],
[
"Tekin",
"Bayram",
""
]
] | We study null and timelike constant radii geodesics in the environment of an over-spinning putative Kerr-type naked singularity. We are particularly interested in two topics: first, the differences of the shadows of the naked rotating singularity and the Kerr black hole; and second, the spinning down effect of the particles falling from the accretion disk. Around the naked singularity, the non-equatorial prograde orbits in the Kerr black hole remain intact up to a critical rotation parameter ($\alpha=\sqrt{6 \sqrt{3}-9}$) and cease to exist above this value [Eur. Phys. J. C 78, 879 (2018)]. This has an important consequence in the shadow of the naked singularity if the shadow is registered by an observer on the polar plane or close to it as the shadow cannot be distinguished from that of a Kerr black hole viewed from the same angle considering only the light emanating from the unstable photon orbits. We show that the timelike retrograde orbits in the equatorial plane immediately (after about an 8% increase in mass for the case of initial $\alpha=1.5$) reduce the spin parameter of the naked singularity from larger values to $\alpha=1$ at which an event horizon appears. This happens because the retrograde orbits have a larger capture cross-section than the prograde ones. So if a naked singularity happens to have an accretion disk, it will not remain naked for long, an event horizon forms. |
2309.16497 | Yongqiang Wang | Long-Xing Huang, Shi-Xian Sun, Rong Zhang, Chen Liang, and Yong-Qiang
Wang | Excited Dirac stars with higher azimuthal harmonic index | 22 pages, 8 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we investigate the properties of the first excited state Dirac
stars (DSs) with higher azimuthal harmonic index (specifically, the azimuthal
harmonic indexes $m_D$ = $3/2$, $5/2$, $7/2$), as well as the relationship
between the ADM mass and angular momentum of Dirac stars with respect to
frequency. Moreover, We find that the ergospheres of DSs appear at lower spinor
field frequencies, and both the ergospheres and the distribution of the spinor
field functions are asymmetric about the equatorial plane. Furthermore, we
introduce the ground state scalar field and examine its impact on this system,
which is known as the multi-state Dirac-boson stars (DBSs) model. We show
various types of solution families for DBSs under both synchronized frequency
$\omega$ and nonsynchronized frequencies and find that similar to DSs, the
spinor field and the ergospheres of DBSs are also asymmetric about the
equatorial plane, but the ergospheres appear at higher spinor field
frequencies.
| [
{
"created": "Thu, 28 Sep 2023 15:05:29 GMT",
"version": "v1"
}
] | 2023-09-29 | [
[
"Huang",
"Long-Xing",
""
],
[
"Sun",
"Shi-Xian",
""
],
[
"Zhang",
"Rong",
""
],
[
"Liang",
"Chen",
""
],
[
"Wang",
"Yong-Qiang",
""
]
] | In this paper, we investigate the properties of the first excited state Dirac stars (DSs) with higher azimuthal harmonic index (specifically, the azimuthal harmonic indexes $m_D$ = $3/2$, $5/2$, $7/2$), as well as the relationship between the ADM mass and angular momentum of Dirac stars with respect to frequency. Moreover, We find that the ergospheres of DSs appear at lower spinor field frequencies, and both the ergospheres and the distribution of the spinor field functions are asymmetric about the equatorial plane. Furthermore, we introduce the ground state scalar field and examine its impact on this system, which is known as the multi-state Dirac-boson stars (DBSs) model. We show various types of solution families for DBSs under both synchronized frequency $\omega$ and nonsynchronized frequencies and find that similar to DSs, the spinor field and the ergospheres of DBSs are also asymmetric about the equatorial plane, but the ergospheres appear at higher spinor field frequencies. |
0907.0891 | Nathan Johnson-McDaniel | Nathan K. Johnson-McDaniel, Nicolas Yunes, Wolfgang Tichy, Benjamin J.
Owen | Conformally curved binary black hole initial data including tidal
deformations and outgoing radiation | 48 pages, 23 figures | Phys.Rev.D80:124039,2009 | 10.1103/PhysRevD.80.124039 | IGC-09/7-1 | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | (Abridged) By asymptotically matching a post-Newtonian (PN) metric to two
tidally perturbed Schwarzschild metrics, we generate approximate initial data
(in the form of a 4-metric) for a nonspinning black hole binary in a circular
orbit. We carry out this matching through O(v^4) in the binary's orbital
velocity v, so the resulting data are conformally curved. Far from the holes,
we use the appropriate PN metric that accounts for retardation, which we
construct using the highest-order PN expressions available to compute the
binary's past history. The data set's uncontrolled remainders are thus O(v^5)
throughout the timeslice; we also generate an extension to the data set that
has uncontrolled remainders of O(v^6) in the purely PN portion of the timeslice
(i.e., not too close to the holes). The resulting data are smooth, since we
join all the metrics together by smoothly interpolating between them. We
perform this interpolation using transition functions constructed to avoid
introducing excessive additional constraint violations. Due to their inclusion
of tidal deformations and outgoing radiation, these data should substantially
reduce the initial spurious ("junk") radiation observed in current simulations
that use conformally flat initial data. Such reductions in the nonphysical
components of the initial data will be necessary for simulations to achieve the
accuracy required to supply Advanced LIGO and LISA with the templates necessary
for parameter estimation.
| [
{
"created": "Mon, 6 Jul 2009 19:06:54 GMT",
"version": "v1"
}
] | 2010-01-07 | [
[
"Johnson-McDaniel",
"Nathan K.",
""
],
[
"Yunes",
"Nicolas",
""
],
[
"Tichy",
"Wolfgang",
""
],
[
"Owen",
"Benjamin J.",
""
]
] | (Abridged) By asymptotically matching a post-Newtonian (PN) metric to two tidally perturbed Schwarzschild metrics, we generate approximate initial data (in the form of a 4-metric) for a nonspinning black hole binary in a circular orbit. We carry out this matching through O(v^4) in the binary's orbital velocity v, so the resulting data are conformally curved. Far from the holes, we use the appropriate PN metric that accounts for retardation, which we construct using the highest-order PN expressions available to compute the binary's past history. The data set's uncontrolled remainders are thus O(v^5) throughout the timeslice; we also generate an extension to the data set that has uncontrolled remainders of O(v^6) in the purely PN portion of the timeslice (i.e., not too close to the holes). The resulting data are smooth, since we join all the metrics together by smoothly interpolating between them. We perform this interpolation using transition functions constructed to avoid introducing excessive additional constraint violations. Due to their inclusion of tidal deformations and outgoing radiation, these data should substantially reduce the initial spurious ("junk") radiation observed in current simulations that use conformally flat initial data. Such reductions in the nonphysical components of the initial data will be necessary for simulations to achieve the accuracy required to supply Advanced LIGO and LISA with the templates necessary for parameter estimation. |
gr-qc/0409083 | Kip S. Thorne | Mihai Bondarescu and Kip S. Thorne (California Institute of
Technology) | A New Family of Light Beams and Mirror Shapes for Future LIGO
Interferometers | Submitted to Physical Review D on 21 September 2004; RevTeX, 6 pages,
4 Figures | Phys.Rev. D74 (2006) 082003 | 10.1103/PhysRevD.74.082003 | null | gr-qc | null | Advanced LIGO's present baseline design uses arm cavities with Gaussian light
beams supported by spherical mirrors. Because Gaussian beams have large
intensity gradients in regions of high intensity, they average poorly over
fluctuating bumps and valleys on the mirror surfaces, caused by random thermal
fluctuations (thermoelastic noise). Flat-topped light beams (mesa beams) are
being considered as an alternative because they average over the thermoelastic
fluctuations much more effectively. However, the proposed mesa beams are
supported by nearly flat mirrors, which experience a very serious tilt
instability. In this paper we propose an alternative configuration in which
mesa-shaped beams are supported by nearly concentric spheres, which experience
only a weak tilt instability. The tilt instability is analyzed for these
mirrors in a companion paper by Savov and Vyatchanin. We also propose a
one-parameter family of light beams and mirrors in which, as the parameter
alpha varies continuously from 0 to pi, the beams and supporting mirrors get
deformed continuously from the nearly flat-mirrored mesa configuration ("FM")
at alpha=0, to the nearly concentric-mirrored mesa configuration ("CM") at
alpha=pi. The FM and CM configurations at the endpoints are close to optically
unstable, and as alpha moves away from 0 or pi, the optical stability improves.
| [
{
"created": "Wed, 22 Sep 2004 17:34:37 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Bondarescu",
"Mihai",
"",
"California Institute of\n Technology"
],
[
"Thorne",
"Kip S.",
"",
"California Institute of\n Technology"
]
] | Advanced LIGO's present baseline design uses arm cavities with Gaussian light beams supported by spherical mirrors. Because Gaussian beams have large intensity gradients in regions of high intensity, they average poorly over fluctuating bumps and valleys on the mirror surfaces, caused by random thermal fluctuations (thermoelastic noise). Flat-topped light beams (mesa beams) are being considered as an alternative because they average over the thermoelastic fluctuations much more effectively. However, the proposed mesa beams are supported by nearly flat mirrors, which experience a very serious tilt instability. In this paper we propose an alternative configuration in which mesa-shaped beams are supported by nearly concentric spheres, which experience only a weak tilt instability. The tilt instability is analyzed for these mirrors in a companion paper by Savov and Vyatchanin. We also propose a one-parameter family of light beams and mirrors in which, as the parameter alpha varies continuously from 0 to pi, the beams and supporting mirrors get deformed continuously from the nearly flat-mirrored mesa configuration ("FM") at alpha=0, to the nearly concentric-mirrored mesa configuration ("CM") at alpha=pi. The FM and CM configurations at the endpoints are close to optically unstable, and as alpha moves away from 0 or pi, the optical stability improves. |
1405.6663 | Salvatore Capozziello | Artyom V. Astashenok, Salvatore Capozziello, Sergei D. Odintsov | Magnetic Neutron Stars in f(R) gravity | 12 pages, 4 figures, 6 tables | null | 10.1007/s10509-014-2182-6 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Neutron stars with strong magnetic fields are considered in the framework of
f(R) gravity. In order to describe dense matter in magnetic field, the model
with baryon octet interacting through $\sigma$$\rho$$\omega$-fields is used.
The hyperonization process results in softening the equation of state (EoS) and
in decreasing the maximal mass. We investigate the effect of strong magnetic
field in models involving quadratic and cubic corrections in the Ricci scalar
$R$ to the Hilbert-Einstein action. For large fields, the Mass-Radius relation
differs considerably from that of General Relativity only for stars with masses
close to the maximal one. Another interesting feature is the possible existence
of more compact stable stars with extremely large magnetic fields ($\sim
6\times 10^{18}$ G instead of $\sim 4\times 10^{18}$ G as in General
Relativity) in the central regions of the stars. Due to cubic terms, a
significant increasing of the maximal mass is possible.
| [
{
"created": "Mon, 26 May 2014 18:05:03 GMT",
"version": "v1"
}
] | 2015-06-19 | [
[
"Astashenok",
"Artyom V.",
""
],
[
"Capozziello",
"Salvatore",
""
],
[
"Odintsov",
"Sergei D.",
""
]
] | Neutron stars with strong magnetic fields are considered in the framework of f(R) gravity. In order to describe dense matter in magnetic field, the model with baryon octet interacting through $\sigma$$\rho$$\omega$-fields is used. The hyperonization process results in softening the equation of state (EoS) and in decreasing the maximal mass. We investigate the effect of strong magnetic field in models involving quadratic and cubic corrections in the Ricci scalar $R$ to the Hilbert-Einstein action. For large fields, the Mass-Radius relation differs considerably from that of General Relativity only for stars with masses close to the maximal one. Another interesting feature is the possible existence of more compact stable stars with extremely large magnetic fields ($\sim 6\times 10^{18}$ G instead of $\sim 4\times 10^{18}$ G as in General Relativity) in the central regions of the stars. Due to cubic terms, a significant increasing of the maximal mass is possible. |
2209.04433 | Kimet Jusufi | Kimet Jusufi | Regular black holes in three dimensions and the zero point length | 4 pages | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, by means of regularisation procedure via $r\to
\sqrt{r^2+l_0^2}$ (where $l_0$ can play the role of zero point length), we
first modify the gravitational and electromagnetic potentials in two dimensions
and then we solve the Einstein field equations to end up with an exact and
regular black hole solution in three dimensions with a negative cosmological
constant. We show that, the black hole solution is asymptotically AdS,
non-singular at the origin and, under specific conditions, it has a flat de
Sitter core at the origin. As a special case, we obtain the charged
Banados-Teitelboim-Zanelli (BTZ) solution. Finally, using a dimensional
continuation and the NJ algorithm, we end up with a legitimate rotating black
hole solution in three dimensions.
| [
{
"created": "Thu, 8 Sep 2022 08:41:46 GMT",
"version": "v1"
}
] | 2022-09-12 | [
[
"Jusufi",
"Kimet",
""
]
] | In this paper, by means of regularisation procedure via $r\to \sqrt{r^2+l_0^2}$ (where $l_0$ can play the role of zero point length), we first modify the gravitational and electromagnetic potentials in two dimensions and then we solve the Einstein field equations to end up with an exact and regular black hole solution in three dimensions with a negative cosmological constant. We show that, the black hole solution is asymptotically AdS, non-singular at the origin and, under specific conditions, it has a flat de Sitter core at the origin. As a special case, we obtain the charged Banados-Teitelboim-Zanelli (BTZ) solution. Finally, using a dimensional continuation and the NJ algorithm, we end up with a legitimate rotating black hole solution in three dimensions. |
gr-qc/9512021 | Gerard Clement | G\'erard Cl\'ement | Gravitating Chern-Simons vortices | 11 pages, LaTex | Phys.Rev. D54 (1996) 1844-1847 | 10.1103/PhysRevD.54.1844 | GCR-95/12/01 | gr-qc hep-th | null | The construction of self-dual vortex solutions to the Chern-Simons-Higgs
model (with a suitable eighth-order potential) coupled to Einstein gravity in
(2 + 1) dimensions is reconsidered. We show that the self-duality condition may
be derived from the sole assumption $g_{00} = 1$. Next, we derive a family of
exact, doubly self-dual vortex solutions, which interpolate between the
symmetrical and asymmetrical vacua. The corresponding spacetimes have two
regions at spatial infinity. The eighth-order Higgs potential is positive
definite, and closed timelike curves are absent, if the gravitational constant
is chosen to be negative.
| [
{
"created": "Mon, 11 Dec 1995 09:58:57 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Clément",
"Gérard",
""
]
] | The construction of self-dual vortex solutions to the Chern-Simons-Higgs model (with a suitable eighth-order potential) coupled to Einstein gravity in (2 + 1) dimensions is reconsidered. We show that the self-duality condition may be derived from the sole assumption $g_{00} = 1$. Next, we derive a family of exact, doubly self-dual vortex solutions, which interpolate between the symmetrical and asymmetrical vacua. The corresponding spacetimes have two regions at spatial infinity. The eighth-order Higgs potential is positive definite, and closed timelike curves are absent, if the gravitational constant is chosen to be negative. |
1507.04076 | Peter Zimmerman | Peter Zimmerman | Gravitational self-force in scalar-tensor gravity | 26 pages. minor typographical errors corrected in v2 | Phys. Rev. D 92, 064051 (2015) | 10.1103/PhysRevD.92.064051 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Motivated by the discovery of floating orbits and the potential to provide
extra constraints on alternative theories, in this paper we derive the
self-force equation for a small compact object moving on an accelerated world
line in a background spacetime which is a solution of the coupled gravitational
and scalar field equations of scalar-tensor theory. In the Einstein frame, the
coupled field equations governing the perturbations sourced by the particle
share the same form as the field equations for perturbations of a scalarvac
spacetime, with both falling under the general class of hyperbolic field
equations studied by Zimmerman and Poisson. Here, we solve the field equations
formally in terms of retarded Green functions, which have explicit
representations as Hadamard forms in the neighbourhood of the world line. Using
a quasi-local expansion of the Hadamard form, we derive the regular solutions
in Fermi normal coordinates according to the Detweiler-Whiting prescription. To
compute the equation of motion, we parameterize the world line in terms of a
mass and "charge", which we define in terms of the original Jordan frame mass,
its derivative, and the parameter which translates the proper time in the
Jordan frame to the Einstein frame. These parameters depend on the value of the
background scalar field and its self-field corrections. The equation of motion
which follows from the regular fields strongly resembles the equation for the
self-force acting on a charged, massive particle in a scalarvac geometry of
general relativity. Unlike the scalar vacuum scenario, the "charge" parameter
in the scalar-tensor self-force equation is time variable and leading to
additional local and tail terms. We also provide evolution equations for the
world line parameters under the influence of the self-fields.
| [
{
"created": "Wed, 15 Jul 2015 03:25:01 GMT",
"version": "v1"
},
{
"created": "Sat, 7 Nov 2015 06:52:24 GMT",
"version": "v2"
}
] | 2015-11-10 | [
[
"Zimmerman",
"Peter",
""
]
] | Motivated by the discovery of floating orbits and the potential to provide extra constraints on alternative theories, in this paper we derive the self-force equation for a small compact object moving on an accelerated world line in a background spacetime which is a solution of the coupled gravitational and scalar field equations of scalar-tensor theory. In the Einstein frame, the coupled field equations governing the perturbations sourced by the particle share the same form as the field equations for perturbations of a scalarvac spacetime, with both falling under the general class of hyperbolic field equations studied by Zimmerman and Poisson. Here, we solve the field equations formally in terms of retarded Green functions, which have explicit representations as Hadamard forms in the neighbourhood of the world line. Using a quasi-local expansion of the Hadamard form, we derive the regular solutions in Fermi normal coordinates according to the Detweiler-Whiting prescription. To compute the equation of motion, we parameterize the world line in terms of a mass and "charge", which we define in terms of the original Jordan frame mass, its derivative, and the parameter which translates the proper time in the Jordan frame to the Einstein frame. These parameters depend on the value of the background scalar field and its self-field corrections. The equation of motion which follows from the regular fields strongly resembles the equation for the self-force acting on a charged, massive particle in a scalarvac geometry of general relativity. Unlike the scalar vacuum scenario, the "charge" parameter in the scalar-tensor self-force equation is time variable and leading to additional local and tail terms. We also provide evolution equations for the world line parameters under the influence of the self-fields. |
1708.09019 | Maria Cecilia Tomasini | Emilio Rub\'in de Celis, Cecilia Tomasini, Claudio Simeone | Perturbative dynamics of thin-shell wormholes beyond general relativity:
an alternative approach | To appear in IJMPD 1750171 | null | 10.1142/S0218271817501711 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recent studies relating the approximations for the equations of state for
thin shells and their consequent perturbative evolution are extended to
thin-shell wormholes in theories beyond general relativity and more than four
spacetime dimensions. The assumption of equations of state of the same form for
static and slowly evolving shells appears as a strong restriction excluding the
possibility of oscillatory evolutions. Then the new results considerably differ
from previous ones obtained within the usual linearized approach.
| [
{
"created": "Tue, 29 Aug 2017 20:38:48 GMT",
"version": "v1"
}
] | 2018-01-10 | [
[
"de Celis",
"Emilio Rubín",
""
],
[
"Tomasini",
"Cecilia",
""
],
[
"Simeone",
"Claudio",
""
]
] | Recent studies relating the approximations for the equations of state for thin shells and their consequent perturbative evolution are extended to thin-shell wormholes in theories beyond general relativity and more than four spacetime dimensions. The assumption of equations of state of the same form for static and slowly evolving shells appears as a strong restriction excluding the possibility of oscillatory evolutions. Then the new results considerably differ from previous ones obtained within the usual linearized approach. |
0805.3794 | Burin Gumjudpai | Theerakarn Phetnora (TPTP Naresuan U.), Roongtum Sooksan (TPTP
Naresuan U.) and Burin Gumjudpai (TPTP Naresuan U. and DAMTP U. Cambridge) | Phantom expansion with non-linear Schr\"{o}dinger-type formulation of
scalar field cosmology | [11 pages, 8 figures] Some parts of this work was presented as an
oral presentation by Theerakarn Phetnora at the SIAM Physics Congress 2008,
Kao Yai, Thailand (20-22 March 2008), accepted by Gen. Rel. Grav | Gen.Rel.Grav.42:225-240,2010 | 10.1007/s10714-009-0831-9 | null | gr-qc astro-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We describe non-flat standard Friedmann cosmology of canonical scalar field
with barotropic fluid in form of non-linear
Schr\"{o}dinger-type (NLS) formulation in which all cosmological dynamical
quantities are expressed in term of Schr\"{o}dinger quantities as similar to
those in time-independent quantum mechanics. We assume the expansion to be
superfast, i.e. phantom expansion. We report all Schr\"{o}dinger-analogous
quantities to scalar field cosmology.
Effective equation of state coefficient is analyzed and illustrated. We show
that in a non-flat universe, there is no fixed $w_{\rm eff}$ value for the
phantom divide. In a non-flat universe, even $w_{\rm eff} > -1$, the expansion
can be phantom. Moreover, in open universe, phantom expansion can happen even
with $w_{\rm eff} > 0$. We also report scalar field exact solutions within
frameworks of the Friedmann formulation and the NLS formulation in non-flat
universe cases.
| [
{
"created": "Sat, 24 May 2008 21:07:38 GMT",
"version": "v1"
},
{
"created": "Mon, 18 May 2009 16:20:46 GMT",
"version": "v2"
}
] | 2014-11-18 | [
[
"Phetnora",
"Theerakarn",
"",
"TPTP Naresuan U."
],
[
"Sooksan",
"Roongtum",
"",
"TPTP\n Naresuan U."
],
[
"Gumjudpai",
"Burin",
"",
"TPTP Naresuan U. and DAMTP U. Cambridge"
]
] | We describe non-flat standard Friedmann cosmology of canonical scalar field with barotropic fluid in form of non-linear Schr\"{o}dinger-type (NLS) formulation in which all cosmological dynamical quantities are expressed in term of Schr\"{o}dinger quantities as similar to those in time-independent quantum mechanics. We assume the expansion to be superfast, i.e. phantom expansion. We report all Schr\"{o}dinger-analogous quantities to scalar field cosmology. Effective equation of state coefficient is analyzed and illustrated. We show that in a non-flat universe, there is no fixed $w_{\rm eff}$ value for the phantom divide. In a non-flat universe, even $w_{\rm eff} > -1$, the expansion can be phantom. Moreover, in open universe, phantom expansion can happen even with $w_{\rm eff} > 0$. We also report scalar field exact solutions within frameworks of the Friedmann formulation and the NLS formulation in non-flat universe cases. |
gr-qc/0212030 | Yasunori Fujii | Yasunori Fujii | Mass of the dilaton and the cosmological constant | 9 pages LaTeX 1 figure; an added reference and partial revisions | Prog.Theor.Phys.110:433-439,2003 | 10.1143/PTP.110.433 | null | gr-qc | null | One might raise a question if the gravitational scalar field (dilaton)
mediates a finite-range force between local objects still behaving globally as
being massless to implement the scenario of a decaying cosmological constant.
We offer a non-negative reply by a detailed analysis of the field-theoretical
quantization procedure in relation to the observationally required suppression
of the vacuum-energy.
| [
{
"created": "Fri, 6 Dec 2002 07:36:15 GMT",
"version": "v1"
},
{
"created": "Sat, 7 Dec 2002 03:54:50 GMT",
"version": "v2"
},
{
"created": "Sat, 8 Feb 2003 02:35:50 GMT",
"version": "v3"
}
] | 2008-11-26 | [
[
"Fujii",
"Yasunori",
""
]
] | One might raise a question if the gravitational scalar field (dilaton) mediates a finite-range force between local objects still behaving globally as being massless to implement the scenario of a decaying cosmological constant. We offer a non-negative reply by a detailed analysis of the field-theoretical quantization procedure in relation to the observationally required suppression of the vacuum-energy. |
gr-qc/0407113 | Wei-Tou Ni | Wei-Tou Ni | Probing the Microscopic Origin of Gravity via Precision Polarization and
Spin Experiments | 8 pages; 1 figure | Chin.Phys.Lett. 22 (2005) 33-35 | 10.1088/0256-307X/22/1/010 | null | gr-qc | null | As in other parts of physics, we advocate the interaction approach:
experiments <--> phenomenology <--> low-energy effective (field) theory <-->
microscopic theory to probe the microscopic origin of gravity. Using chi-g
phenomenological framework, we discuss the tests of equivalence principles. The
only experimentally unconstrained degree of freedom is the axion freedom. It
has effects on the long-range astrophysical/cosmological propagation of
electromagnetic waves and can be tested/measured using future generation of
polarization measurement of cosmic background radiation. The verification or
refutal of this axionic effect will be a crucial step for constructing
effective theory and probing the microscopic origin of gravity. The interaction
of spin with gravity is another important clue for probing microscopic origin
of gravity. The interplay of experiments, phenomenology and effective theory is
expounded. An ideal way to reveal the microscopic origin of gravity is to
measure the gyrogravitational ratio of particles. Three potential experimental
methods are considered.
| [
{
"created": "Thu, 29 Jul 2004 12:39:21 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Ni",
"Wei-Tou",
""
]
] | As in other parts of physics, we advocate the interaction approach: experiments <--> phenomenology <--> low-energy effective (field) theory <--> microscopic theory to probe the microscopic origin of gravity. Using chi-g phenomenological framework, we discuss the tests of equivalence principles. The only experimentally unconstrained degree of freedom is the axion freedom. It has effects on the long-range astrophysical/cosmological propagation of electromagnetic waves and can be tested/measured using future generation of polarization measurement of cosmic background radiation. The verification or refutal of this axionic effect will be a crucial step for constructing effective theory and probing the microscopic origin of gravity. The interaction of spin with gravity is another important clue for probing microscopic origin of gravity. The interplay of experiments, phenomenology and effective theory is expounded. An ideal way to reveal the microscopic origin of gravity is to measure the gyrogravitational ratio of particles. Three potential experimental methods are considered. |
0810.3911 | Fabrizio Tamburini | Clovis Jacinto de Matos (1), Fabrizio Tamburini (2), Josep Maria
Perdigues Armengol (3) and Carlo Nicola Colacino (4) ((1) ESA-HQ, European
Space Agency, 8-10 rue Mario Nikis, Paris, France (2) Dept. of Astronomy,
University of Padova, vicolo dell'Osservatorio 3, Padova, Italy (3)
ESA-ESTEC, European Space Agency, Keplerlaan 1, AG Noordwijk ZH, the
Netherlands, (4) Dept. of Physics, University of Pisa, Largo B. Pontecorvo 3,
Pisa, Italy) | Gravitational Waves detection and spectroscopy with a Double-slit
Quantum Eraser | 14 pages, 2 figures, accepted for publication in NCB | null | null | null | gr-qc astro-ph quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose the use of heralded photons to detect Gravitational Waves (GWs).
Heralded photons are those photons that, produced during a parametric
downconversion process, are "labelled" by the detection and counting of
coincidences of their correlated or entangled twins and therefore can be
discriminated from the background noise, independently of the type of
correlation/entanglement used in the setup. Without losing any generality, we
illustrate our proposal with a gedankenexperiment, in which the presence of a
gravitational wave causes a relative rotation of the reference frames
associated to the double-slit and the test polarizer, respectively, of a
Walborn's quantum eraser \cite{wal02}. In this thought experiment, the GW is
revealed by the detection of heralded photons in the dark fringes of the
recovered interference pattern by the quantum eraser. Other types of
entanglement, such as momentum-space or energy-time, could be used to obtain
heralded photons to be used in the future with high-frequency GW
interferometric detectors when enough bright sources of correlated photons will
be available.
| [
{
"created": "Tue, 21 Oct 2008 19:57:24 GMT",
"version": "v1"
},
{
"created": "Tue, 8 Sep 2009 07:41:49 GMT",
"version": "v2"
}
] | 2009-09-08 | [
[
"de Matos",
"Clovis Jacinto",
""
],
[
"Tamburini",
"Fabrizio",
""
],
[
"Armengol",
"Josep Maria Perdigues",
""
],
[
"Colacino",
"Carlo Nicola",
""
]
] | We propose the use of heralded photons to detect Gravitational Waves (GWs). Heralded photons are those photons that, produced during a parametric downconversion process, are "labelled" by the detection and counting of coincidences of their correlated or entangled twins and therefore can be discriminated from the background noise, independently of the type of correlation/entanglement used in the setup. Without losing any generality, we illustrate our proposal with a gedankenexperiment, in which the presence of a gravitational wave causes a relative rotation of the reference frames associated to the double-slit and the test polarizer, respectively, of a Walborn's quantum eraser \cite{wal02}. In this thought experiment, the GW is revealed by the detection of heralded photons in the dark fringes of the recovered interference pattern by the quantum eraser. Other types of entanglement, such as momentum-space or energy-time, could be used to obtain heralded photons to be used in the future with high-frequency GW interferometric detectors when enough bright sources of correlated photons will be available. |
2203.09867 | Vasilis Oikonomou | V.K. Oikonomou, P.D. Katzanis, Ilias C. Papadimitriou | Bottom-Up Reconstruction of Viable GW170817 Compatible
Einstein-Gauss-Bonnet Theories | CQG accepted, some typos corrected, one author name modified, doi
added | null | 10.1088/1361-6382/ac5eba | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we shall use a bottom-up approach for obtaining viable
inflationary Einstein-Gauss-Bonnet models which are also compatible with the
GW170817 event. Specifically, we shall use a recently developed theoretical
framework in which we shall specify only the tensor-to-scalar ratio, in terms
of the $e$-foldings number. Starting from the tensor-to-scalar ratio, we shall
reconstruct from it the Einstein-Gauss-Bonnet theory which can yield such a
tensor-to-scalar ratio, finding the scalar potential and the Gauss-Bonnet
coupling scalar function as functions of the $e$-foldings number. Accordingly,
the calculation of the spectral index of the primordial scalar perturbations,
and of the tensor spectral index easily is greatly simplified and these
observational indices can easily be found. After presenting the general
formalism for the bottom-up reconstruction, we exemplify our findings by
presenting several Einstein-Gauss-Bonnet models of interest which yield a
viable inflationary phenomenology. These models have also an interesting common
characteristic, which is a blue tilted tensor spectral index. We also
investigate the predicted energy spectrum of the primordial gravitational waves
for these Einstein-Gauss-Bonnet models, and as we show, all the models yield a
detectable primordial wave energy power spectrum.
| [
{
"created": "Fri, 18 Mar 2022 11:14:25 GMT",
"version": "v1"
},
{
"created": "Wed, 23 Mar 2022 12:09:30 GMT",
"version": "v2"
}
] | 2022-03-24 | [
[
"Oikonomou",
"V. K.",
""
],
[
"Katzanis",
"P. D.",
""
],
[
"Papadimitriou",
"Ilias C.",
""
]
] | In this work we shall use a bottom-up approach for obtaining viable inflationary Einstein-Gauss-Bonnet models which are also compatible with the GW170817 event. Specifically, we shall use a recently developed theoretical framework in which we shall specify only the tensor-to-scalar ratio, in terms of the $e$-foldings number. Starting from the tensor-to-scalar ratio, we shall reconstruct from it the Einstein-Gauss-Bonnet theory which can yield such a tensor-to-scalar ratio, finding the scalar potential and the Gauss-Bonnet coupling scalar function as functions of the $e$-foldings number. Accordingly, the calculation of the spectral index of the primordial scalar perturbations, and of the tensor spectral index easily is greatly simplified and these observational indices can easily be found. After presenting the general formalism for the bottom-up reconstruction, we exemplify our findings by presenting several Einstein-Gauss-Bonnet models of interest which yield a viable inflationary phenomenology. These models have also an interesting common characteristic, which is a blue tilted tensor spectral index. We also investigate the predicted energy spectrum of the primordial gravitational waves for these Einstein-Gauss-Bonnet models, and as we show, all the models yield a detectable primordial wave energy power spectrum. |
2110.14736 | Samuel Barroso Bellido | Samuel Barroso Bellido | Effects of a Quantum or Classical Scalar Field on the Entanglement
Entropy of a Pair of Universes | Accepted for publication in PRD. 3 Figures | Phys. Rev. D 104, 106009 (2021) | 10.1103/PhysRevD.104.106009 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Using the formalism of the third quantization in canonical quantum gravity,
the entropy of entanglement of a pair of universes created in the multiverse
from the vacuum has lately been calculated. Here, we examine the differences
between considering a scalar field as quantum or classical on the entanglement
entropy of three different pairs: de-Sitter universes, flat stiff matter
dominated universes, and closed universes with a scalar field. We find that the
entanglement entropy is unchanged, zero, or dependent on the treatment of the
scalar field, respectively.
| [
{
"created": "Wed, 27 Oct 2021 19:42:01 GMT",
"version": "v1"
}
] | 2021-11-17 | [
[
"Bellido",
"Samuel Barroso",
""
]
] | Using the formalism of the third quantization in canonical quantum gravity, the entropy of entanglement of a pair of universes created in the multiverse from the vacuum has lately been calculated. Here, we examine the differences between considering a scalar field as quantum or classical on the entanglement entropy of three different pairs: de-Sitter universes, flat stiff matter dominated universes, and closed universes with a scalar field. We find that the entanglement entropy is unchanged, zero, or dependent on the treatment of the scalar field, respectively. |
1510.08821 | Giampiero Esposito Dr. | Giampiero Esposito | A parametrix for quantum gravity? | 27 pages | Int. J. Geom. Methods Mod. Phys. 13, 1650060 (2016) | 10.1142/S0219887816500602 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the sixties, DeWitt discovered that the advanced and retarded Green
functions of the wave operator on metric perturbations in the de Donder gauge
make it possible to define classical Poisson brackets on the space of
functionals that are invariant under the action of the full diffeomorphism
group of spacetime. He therefore tried to exploit this property to define
invariant commutators for the quantized gravitational field, but the operator
counterpart of such classical Poisson brackets turned out to be a hard task. On
the other hand, the mathematical literature studies often an approximate
inverse, the parametrix, which is, strictly, a distribution. We here suggest
that such a construction might be exploited in canonical quantum gravity. We
begin with the simplest case, i.e. fundamental solution and parametrix for the
linear, scalar wave operator; the next step are tensor wave equations, again
for linear theory, e.g. Maxwell theory in curved spacetime. Last, the nonlinear
Einstein equations are studied, relying upon the well-established
Choquet-Bruhat construction, according to which the fifth derivatives of
solutions of a nonlinear hyperbolic system solve a linear hyperbolic system.
The latter is solved by means of Kirchhoff-type formulas, while the former
fifth-order equations can be solved by means of well-established parametrix
techniques for elliptic operators. But then the metric components that solve
the vacuum Einstein equations can be obtained by convolution of such a
parametrix with Kirchhoff-type formulas. Some basic functional equations for
the parametrix are also obtained, that help in studying classical and quantum
version of the Jacobi identity.
| [
{
"created": "Thu, 29 Oct 2015 18:58:07 GMT",
"version": "v1"
},
{
"created": "Thu, 17 Mar 2016 16:11:08 GMT",
"version": "v2"
}
] | 2016-03-18 | [
[
"Esposito",
"Giampiero",
""
]
] | In the sixties, DeWitt discovered that the advanced and retarded Green functions of the wave operator on metric perturbations in the de Donder gauge make it possible to define classical Poisson brackets on the space of functionals that are invariant under the action of the full diffeomorphism group of spacetime. He therefore tried to exploit this property to define invariant commutators for the quantized gravitational field, but the operator counterpart of such classical Poisson brackets turned out to be a hard task. On the other hand, the mathematical literature studies often an approximate inverse, the parametrix, which is, strictly, a distribution. We here suggest that such a construction might be exploited in canonical quantum gravity. We begin with the simplest case, i.e. fundamental solution and parametrix for the linear, scalar wave operator; the next step are tensor wave equations, again for linear theory, e.g. Maxwell theory in curved spacetime. Last, the nonlinear Einstein equations are studied, relying upon the well-established Choquet-Bruhat construction, according to which the fifth derivatives of solutions of a nonlinear hyperbolic system solve a linear hyperbolic system. The latter is solved by means of Kirchhoff-type formulas, while the former fifth-order equations can be solved by means of well-established parametrix techniques for elliptic operators. But then the metric components that solve the vacuum Einstein equations can be obtained by convolution of such a parametrix with Kirchhoff-type formulas. Some basic functional equations for the parametrix are also obtained, that help in studying classical and quantum version of the Jacobi identity. |
1110.6008 | Bibhas Majhi Ranjan | Bibhas Ranjan Majhi | Quantum Tunneling in Black Holes | Ph.D. thesis (arXiv version). 139 pages, including the front matter.
Supervisor: Rabin Banerjee. Institution: S.N. Bose National Centre for Basic
Sciences, Kolkata, India. Degree awarded on 23 August 2011 from University of
Calcutta, Kolkata, India | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/3.0/ | This thesis is focussed towards the applications of the quantum tunneling
mechanism to study black holes. Here we give a general frame work of the
existing tunneling mechanism, both the radial null geodesic and Hamilton Jacobi
methods. On the radial null geodesic method side, we study the modifications to
the tunneling rate, Hawking temperature and the Bekenstein- Hawking area law by
including the back reaction as well as non-commutative effects in the
space-time. A reformulation of the Hamilton-Jacobi (HJ) method is first
introduced. Based on this, a close connection between the quantum tunneling and
the gravitational anomaly mechanisms to discuss Hawking effect, is put
forwarded. An interesting advantage of this reformulated HJ method is that one
can get directly the emission spectrum from the event horizon of the black
hole, which was missing in the earlier literature. Also, the quantization of
the entropy and area of a black hole is discussed in this method. Another part
of the thesis is the introduction of a new type of global embedding of curved
space-time to higher dimensional Minkowskian space-time (GEMS). Using this a
unified description of the Hawking and Unruh effects is given. Advantage of
this approach is, it simplifies as well as generalises the conventional
embedding. In addition to the spherically symmetric space-times, the
Kerr-Newman black hole is exemplified. Finally, following the above ideas and
the definition of partition function for gravity, it is shown that
extremization of entropy leads to the Einstein's equations of motion. In this
frame work, a relation between the entropy, energy and the temperature of a
black hole is given where energy is shown to be the Komar expression.
Interestingly, this relation is the generalized Smarr formula. In this
analysis, the GEMS method provides the law of equipartition of energy as an
intermediate step.
| [
{
"created": "Thu, 27 Oct 2011 08:30:41 GMT",
"version": "v1"
}
] | 2011-10-28 | [
[
"Majhi",
"Bibhas Ranjan",
""
]
] | This thesis is focussed towards the applications of the quantum tunneling mechanism to study black holes. Here we give a general frame work of the existing tunneling mechanism, both the radial null geodesic and Hamilton Jacobi methods. On the radial null geodesic method side, we study the modifications to the tunneling rate, Hawking temperature and the Bekenstein- Hawking area law by including the back reaction as well as non-commutative effects in the space-time. A reformulation of the Hamilton-Jacobi (HJ) method is first introduced. Based on this, a close connection between the quantum tunneling and the gravitational anomaly mechanisms to discuss Hawking effect, is put forwarded. An interesting advantage of this reformulated HJ method is that one can get directly the emission spectrum from the event horizon of the black hole, which was missing in the earlier literature. Also, the quantization of the entropy and area of a black hole is discussed in this method. Another part of the thesis is the introduction of a new type of global embedding of curved space-time to higher dimensional Minkowskian space-time (GEMS). Using this a unified description of the Hawking and Unruh effects is given. Advantage of this approach is, it simplifies as well as generalises the conventional embedding. In addition to the spherically symmetric space-times, the Kerr-Newman black hole is exemplified. Finally, following the above ideas and the definition of partition function for gravity, it is shown that extremization of entropy leads to the Einstein's equations of motion. In this frame work, a relation between the entropy, energy and the temperature of a black hole is given where energy is shown to be the Komar expression. Interestingly, this relation is the generalized Smarr formula. In this analysis, the GEMS method provides the law of equipartition of energy as an intermediate step. |
1210.5115 | Orlando Luongo | Salvatore Capozziello, Gerardo Cristofano, Mariafelicia De Laurentis,
Orlando Luongo | From Black Hole quantization to universal scaling laws | 3 pages, proceeding MG XIII | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Significative developments on the primordial black hole quantization seem to
indicate that the structure formation in the universe behaves under a unified
scheme. This leads to the existence of scaling relations, whose validity could
offer insights on the process of unification between quantum mechanics and
gravity. Encouraging results have been obtained in order to recover the
observed magnitudes of angular momenta, peculiar radii and virialized times for
large and small structures. In the cosmological regime, we show that it seems
possible to infer the magnitude of the cosmological constant in terms of the
matter density, in agreement with the observed values.
| [
{
"created": "Thu, 18 Oct 2012 13:41:06 GMT",
"version": "v1"
}
] | 2012-10-22 | [
[
"Capozziello",
"Salvatore",
""
],
[
"Cristofano",
"Gerardo",
""
],
[
"De Laurentis",
"Mariafelicia",
""
],
[
"Luongo",
"Orlando",
""
]
] | Significative developments on the primordial black hole quantization seem to indicate that the structure formation in the universe behaves under a unified scheme. This leads to the existence of scaling relations, whose validity could offer insights on the process of unification between quantum mechanics and gravity. Encouraging results have been obtained in order to recover the observed magnitudes of angular momenta, peculiar radii and virialized times for large and small structures. In the cosmological regime, we show that it seems possible to infer the magnitude of the cosmological constant in terms of the matter density, in agreement with the observed values. |
gr-qc/0009032 | Edward Malec | Edward Malec | How much of the outgoing radiation can be intercepted by
Schwarzschildean black holes? | 5 pages | Acta Phys.Polon. B32 (2001) 47-54 | null | null | gr-qc | null | The Schwarzschild spacetime is for electromagnetic waves like a nonuniform
medium with a varying refraction index. A fraction of an outgoing radiation
scatters off the curvature of the geometry and can be intercepted by a
gravitational center. The amount of the intercepted energy is bounded above by
the backscattered energy of an initially outgoing pulse of electromagnetic
radiation, which in turn depends on the initial energy, the Schwarzschild
radius and the pulse location. Its magnitude depends on the frequency spectrum:
it becomes negligible in the short wave limit but can be significant in the
long wave regime.
| [
{
"created": "Mon, 11 Sep 2000 14:09:28 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Malec",
"Edward",
""
]
] | The Schwarzschild spacetime is for electromagnetic waves like a nonuniform medium with a varying refraction index. A fraction of an outgoing radiation scatters off the curvature of the geometry and can be intercepted by a gravitational center. The amount of the intercepted energy is bounded above by the backscattered energy of an initially outgoing pulse of electromagnetic radiation, which in turn depends on the initial energy, the Schwarzschild radius and the pulse location. Its magnitude depends on the frequency spectrum: it becomes negligible in the short wave limit but can be significant in the long wave regime. |
1506.03598 | Xin Liu | Sheng-Fei Feng, Chang-Yu Huang, Yong-Chang Huang, Xin Liu, Ying-Jie
Zhao | Symmetry of Generalized Randall-Sundrum Model and Distribution of
3-Branes in Six-Dimensional Spacetime | 12 pages. 1 figure | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A generalization from the usual $5$-dimensional two-brane Randall-Sundrum
(RS) model to a $6$-dimensional multi-brane RS model is presented. The extra
dimensions are extended from one to two; correspondingly the single-variable
warp function is generalized to be a double-variable function, to represent the
two extra dimensions. In the analysis of the Einstein equation we have two
remarkable discoveries. One is that, when branes are absent, the cosmological
parameter distributed in the two extra dimensions acts as a function describing
a family of circles. These circles are not artificially added ones but stem
from the equations of motion, while their radii are inversely proportional to
the square root of the cosmological parameter. The other discovery is that, on
any circle, there symmetrically distribute four branes. Their tensions, $V_1
\sim V_4$, satisfy a particular relationship $V_1=V_3=-V_2=-V_4=3M^4$, where
$M$ is the $6$-dimensional fundamental scale of the RS model.
| [
{
"created": "Thu, 11 Jun 2015 09:27:13 GMT",
"version": "v1"
}
] | 2015-06-12 | [
[
"Feng",
"Sheng-Fei",
""
],
[
"Huang",
"Chang-Yu",
""
],
[
"Huang",
"Yong-Chang",
""
],
[
"Liu",
"Xin",
""
],
[
"Zhao",
"Ying-Jie",
""
]
] | A generalization from the usual $5$-dimensional two-brane Randall-Sundrum (RS) model to a $6$-dimensional multi-brane RS model is presented. The extra dimensions are extended from one to two; correspondingly the single-variable warp function is generalized to be a double-variable function, to represent the two extra dimensions. In the analysis of the Einstein equation we have two remarkable discoveries. One is that, when branes are absent, the cosmological parameter distributed in the two extra dimensions acts as a function describing a family of circles. These circles are not artificially added ones but stem from the equations of motion, while their radii are inversely proportional to the square root of the cosmological parameter. The other discovery is that, on any circle, there symmetrically distribute four branes. Their tensions, $V_1 \sim V_4$, satisfy a particular relationship $V_1=V_3=-V_2=-V_4=3M^4$, where $M$ is the $6$-dimensional fundamental scale of the RS model. |
0811.3297 | Sergey Vyatchanin | Andrey A. Rakhubovsky and Sergey P. Vyatchanin | Displacement- and laser-noise-free gravitational-wave detection with two
Fabry-Perot cavities | 7 pages, 4 figure | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose two Fabry-Perot cavities, each pumped through both the mirrors,
positioned in line as a toy model of the gravitational-wave (GW) detector free
from displacement noise of the test masses. It is demonstrated that the
displacement noise of cavity mirrors as well as laser noise can be completely
excluded in a proper linear combination of the cavities output signals. We show
that in low-frequency approximation (gravitational wave length
$\lambda-\text{gw}$ is much greater than distance $L$ between mirrors
$\lambda_\text{gw}\gg L$) the decrease of response signal is about
$(L/\lambda_\text{gw})^2$, i.e. signal is stronger than the one of the
interferometer recently proposed by S. Kawamura and Y. Chen.
| [
{
"created": "Thu, 20 Nov 2008 09:51:40 GMT",
"version": "v1"
}
] | 2008-11-21 | [
[
"Rakhubovsky",
"Andrey A.",
""
],
[
"Vyatchanin",
"Sergey P.",
""
]
] | We propose two Fabry-Perot cavities, each pumped through both the mirrors, positioned in line as a toy model of the gravitational-wave (GW) detector free from displacement noise of the test masses. It is demonstrated that the displacement noise of cavity mirrors as well as laser noise can be completely excluded in a proper linear combination of the cavities output signals. We show that in low-frequency approximation (gravitational wave length $\lambda-\text{gw}$ is much greater than distance $L$ between mirrors $\lambda_\text{gw}\gg L$) the decrease of response signal is about $(L/\lambda_\text{gw})^2$, i.e. signal is stronger than the one of the interferometer recently proposed by S. Kawamura and Y. Chen. |
1402.7049 | Joan Sola | Joan Sola | Vacuum energy and cosmological evolution | Slightly extended discussion, typos corrected and references added | AIP Conf.Proc. 1606 (2014) 19-37 | 10.1063/1.4891113 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | An expanding universe is not expected to have a static vacuum energy density.
The so-called cosmological constant $\Lambda$ should be an approximation,
certainly a good one for a fraction of a Hubble time, but it is most likely a
temporary description of a true dynamical vacuum energy variable that is
evolving from the inflationary epoch to the present day. We can compare the
evolving vacuum energy with a Casimir device where the parallel plates slowly
move apart ("expand"). The total vacuum energy density cannot be measured, only
the effect associated to the presence of the plates, and then also their
increasing separation with time. In the universe there is a nonvanishing
spacetime curvature $R$ as compared to Minkowskian spacetime that is changing
with the expansion. The vacuum energy density must change accordingly, and we
naturally expect $\delta\Lambda\sim R\sim H^2$. A class of dynamical vacuum
models that trace such rate of change can be constructed. They are compatible
with the current cosmological data, and conveniently extended can account for
the complete cosmic evolution from the inflationary epoch till the present
days. These models are very close to the $\Lambda$CDM model for the late
universe, but very different from it at the early times. Traces of the inherent
vacuum dynamics could be detectable in our recent past.
| [
{
"created": "Thu, 27 Feb 2014 20:10:45 GMT",
"version": "v1"
},
{
"created": "Mon, 3 Mar 2014 13:23:54 GMT",
"version": "v2"
}
] | 2015-03-19 | [
[
"Sola",
"Joan",
""
]
] | An expanding universe is not expected to have a static vacuum energy density. The so-called cosmological constant $\Lambda$ should be an approximation, certainly a good one for a fraction of a Hubble time, but it is most likely a temporary description of a true dynamical vacuum energy variable that is evolving from the inflationary epoch to the present day. We can compare the evolving vacuum energy with a Casimir device where the parallel plates slowly move apart ("expand"). The total vacuum energy density cannot be measured, only the effect associated to the presence of the plates, and then also their increasing separation with time. In the universe there is a nonvanishing spacetime curvature $R$ as compared to Minkowskian spacetime that is changing with the expansion. The vacuum energy density must change accordingly, and we naturally expect $\delta\Lambda\sim R\sim H^2$. A class of dynamical vacuum models that trace such rate of change can be constructed. They are compatible with the current cosmological data, and conveniently extended can account for the complete cosmic evolution from the inflationary epoch till the present days. These models are very close to the $\Lambda$CDM model for the late universe, but very different from it at the early times. Traces of the inherent vacuum dynamics could be detectable in our recent past. |
2304.01607 | Chethan Krishnan | Chethan Krishnan, Jude Pereira | Soft Hair on Schwarzschild: A Wrinkle in Birkhoff's Theorem | 30 pp, no figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The double null form of the Schwarzschild metric is usually arrived at by
demanding Eddington-Finkelstein (EF) conditions at the horizon. This leads to
certain logarithmic fall-offs that are too slow along null directions at
$\mathscr{I}$, resulting in divergences in the covariant surface charges. These
coordinates are therefore $not$ asymptotically flat. In this paper, we find a
natural alternative double null form for Schwarzschild that is adapted to
$\mathscr{I}^{+}$ or $\mathscr{I}^{-}$ instead of the horizon. In its final
form, the metric has only power law fall-offs and fits into the recently
introduced Special Double Null (SDN) gauge, with finite surface charges. One
remarkable feature of SDN gauge is that spherical symmetry and vacuum Einstein
equations allow an infinite number of asymptotic integration constants in the
metric, on top of the mass. This is an apparent violation of Birkhoff's
theorem. We note however that all except two of these new parameters are absent
in the charges, and therefore correspond to trivial hair. The remaining two
parameters do show up in the charges, depending on the choice of allowed
fall-offs. We provide an understanding of this observation -- Birkhoff's
theorem fixes Schwarzschild only $up$ $to$ $diffeomorphisms$, but
diffeomorphisms need not vanish at infinity and can in principle become global
symmetries. If such asymptotic diffeomorphisms are spherically symmetric, their
associated soft modes can become Birkhoff hair. The relevant global symmetries
here are certain hypertranslation shifts in the $v$-coordinate at
$\mathscr{I}^{+}$ (and $u$ at $\mathscr{I}^{-}$), which are inaccessible in
other gauges.
| [
{
"created": "Tue, 4 Apr 2023 08:01:34 GMT",
"version": "v1"
}
] | 2023-04-05 | [
[
"Krishnan",
"Chethan",
""
],
[
"Pereira",
"Jude",
""
]
] | The double null form of the Schwarzschild metric is usually arrived at by demanding Eddington-Finkelstein (EF) conditions at the horizon. This leads to certain logarithmic fall-offs that are too slow along null directions at $\mathscr{I}$, resulting in divergences in the covariant surface charges. These coordinates are therefore $not$ asymptotically flat. In this paper, we find a natural alternative double null form for Schwarzschild that is adapted to $\mathscr{I}^{+}$ or $\mathscr{I}^{-}$ instead of the horizon. In its final form, the metric has only power law fall-offs and fits into the recently introduced Special Double Null (SDN) gauge, with finite surface charges. One remarkable feature of SDN gauge is that spherical symmetry and vacuum Einstein equations allow an infinite number of asymptotic integration constants in the metric, on top of the mass. This is an apparent violation of Birkhoff's theorem. We note however that all except two of these new parameters are absent in the charges, and therefore correspond to trivial hair. The remaining two parameters do show up in the charges, depending on the choice of allowed fall-offs. We provide an understanding of this observation -- Birkhoff's theorem fixes Schwarzschild only $up$ $to$ $diffeomorphisms$, but diffeomorphisms need not vanish at infinity and can in principle become global symmetries. If such asymptotic diffeomorphisms are spherically symmetric, their associated soft modes can become Birkhoff hair. The relevant global symmetries here are certain hypertranslation shifts in the $v$-coordinate at $\mathscr{I}^{+}$ (and $u$ at $\mathscr{I}^{-}$), which are inaccessible in other gauges. |
1401.6182 | Dejan Stojkovic | Anshul Saini, Dejan Stojkovic | Non-local (but also non-singular) physics at the last stages of
gravitational collapse | Published in Phys. Rev. D 89, 044003 (2014) | Phys. Rev. D 89, 044003 (2014) | 10.1103/PhysRevD.89.044003 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the end stages of gravitational collapse of the thin shell of matter
in ingoing Eddington-Finkelstein coordinates. We use the functional Schrodinger
formalism to capture quantum effects in the near singularity limit. We find
that that the equations of motion which govern the behavior of the collapsing
shell near the classical singularity become strongly non-local. This reinforces
previous arguments that quantum gravity in the strong field regime might be
non-local. We managed to solve the non-local equation of motion for the dust
shell case, and found an explicit form of the wavefunction describing the
collapsing shell. This wavefunction and the corresponding probability density
are non-singular at the origin, thus indicating that quantization should be
able to rid gravity of singularities, just as it was the case with the singular
Coulomb potential.
| [
{
"created": "Thu, 23 Jan 2014 21:00:17 GMT",
"version": "v1"
},
{
"created": "Wed, 12 Feb 2014 00:15:16 GMT",
"version": "v2"
},
{
"created": "Tue, 4 Mar 2014 23:27:42 GMT",
"version": "v3"
}
] | 2015-06-18 | [
[
"Saini",
"Anshul",
""
],
[
"Stojkovic",
"Dejan",
""
]
] | We study the end stages of gravitational collapse of the thin shell of matter in ingoing Eddington-Finkelstein coordinates. We use the functional Schrodinger formalism to capture quantum effects in the near singularity limit. We find that that the equations of motion which govern the behavior of the collapsing shell near the classical singularity become strongly non-local. This reinforces previous arguments that quantum gravity in the strong field regime might be non-local. We managed to solve the non-local equation of motion for the dust shell case, and found an explicit form of the wavefunction describing the collapsing shell. This wavefunction and the corresponding probability density are non-singular at the origin, thus indicating that quantization should be able to rid gravity of singularities, just as it was the case with the singular Coulomb potential. |
2110.02542 | Jennifer Rittenhouse West | Francesco Coradeschi, Antonia Micol Frassino, Thiago Guerreiro,
Jennifer Rittenhouse West and Enrico Junior Schioppa | Can we detect the quantum nature of weak gravitational fields? | Submitted to Universe, invited contribution to the topical issue
"Probing Quantum Gravity." | null | 10.3390/universe7110414 | null | gr-qc hep-ph quant-ph | http://creativecommons.org/licenses/by/4.0/ | A theoretical framework for the quantization of gravity has been an elusive
Holy Grail since the birth of quantum theory and general relativity. While
generations of scientists have attempted solutions to this deep riddle, an
alternative path built upon the idea that experimental evidence could determine
whether gravity is quantized has been decades in the making. The possibility of
an experimental answer to the question of the quantization of gravity is of
renewed interest in the era of gravitational wave detectors. We review and
investigate an important subset of phenomenological quantum gravity, detecting
quantum signatures of weak gravitational fields in table-top experiments and
interferometers.
| [
{
"created": "Wed, 6 Oct 2021 07:21:09 GMT",
"version": "v1"
}
] | 2021-11-05 | [
[
"Coradeschi",
"Francesco",
""
],
[
"Frassino",
"Antonia Micol",
""
],
[
"Guerreiro",
"Thiago",
""
],
[
"West",
"Jennifer Rittenhouse",
""
],
[
"Schioppa",
"Enrico Junior",
""
]
] | A theoretical framework for the quantization of gravity has been an elusive Holy Grail since the birth of quantum theory and general relativity. While generations of scientists have attempted solutions to this deep riddle, an alternative path built upon the idea that experimental evidence could determine whether gravity is quantized has been decades in the making. The possibility of an experimental answer to the question of the quantization of gravity is of renewed interest in the era of gravitational wave detectors. We review and investigate an important subset of phenomenological quantum gravity, detecting quantum signatures of weak gravitational fields in table-top experiments and interferometers. |
1903.01445 | Tao Lei | Tao Lei, Zi-Wei Chen, Zhen-Lai Wang, and Xiang-Song Chen* | A New Improved Energy-Momentum Tensor and Its Possible Role in Gravity | 14 pages. arXiv admin note: substantial text overlap with
arXiv:1702.02921, arXiv:1701.08658 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Motivated by a special consideration in quantum measurement, we present a new
improved energy-momentum tensor. The new tensor differs from the traditional
canonical and symmetric ones, and can be derived as Nother current from a
Lagrangian with second derivative. We also attempt to construct a gravitational
coupling in such a way that the new energy-momentum tensor becomes the source
of the gravitational field. The theory we obtain is of an Einstein-Cartan type,
but derived from a minimal coupling of a Lagrangian with second-derivative, and
leads to additional interaction between torsion and matter, including the
scalar field. For the scalar field, the theory can also be derived in the
Riemann space-time by a non-minimal coupling. Our study gives hint on more
general tests of general relativistic effects.
| [
{
"created": "Sun, 3 Mar 2019 13:03:49 GMT",
"version": "v1"
}
] | 2019-03-06 | [
[
"Lei",
"Tao",
""
],
[
"Chen",
"Zi-Wei",
""
],
[
"Wang",
"Zhen-Lai",
""
],
[
"Chen*",
"Xiang-Song",
""
]
] | Motivated by a special consideration in quantum measurement, we present a new improved energy-momentum tensor. The new tensor differs from the traditional canonical and symmetric ones, and can be derived as Nother current from a Lagrangian with second derivative. We also attempt to construct a gravitational coupling in such a way that the new energy-momentum tensor becomes the source of the gravitational field. The theory we obtain is of an Einstein-Cartan type, but derived from a minimal coupling of a Lagrangian with second-derivative, and leads to additional interaction between torsion and matter, including the scalar field. For the scalar field, the theory can also be derived in the Riemann space-time by a non-minimal coupling. Our study gives hint on more general tests of general relativistic effects. |
1110.5631 | Philipp Hoehn | Philipp A. Hoehn | Effective relational dynamics | 4 pages, based on a talk given at Loops '11 in Madrid, to appear in
Journal of Physics: Conference Series (JPCS) | null | 10.1088/1742-6596/360/1/012014 | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide a synopsis of an effective approach to the problem of time in the
semiclassical regime. The essential features of this new approach to evaluating
relational quantum dynamics in constrained systems are illustrated by means of
a simple toy model.
| [
{
"created": "Tue, 25 Oct 2011 19:58:07 GMT",
"version": "v1"
}
] | 2015-05-30 | [
[
"Hoehn",
"Philipp A.",
""
]
] | We provide a synopsis of an effective approach to the problem of time in the semiclassical regime. The essential features of this new approach to evaluating relational quantum dynamics in constrained systems are illustrated by means of a simple toy model. |
2402.02386 | Xuefeng Zhang | Dezhi Wang, Xuefeng Zhang, Hui-Zong Duan | On point-ahead angle control strategies for TianQin | 9 pages, 13 figures | Class. Quantum Grav. 41, 117003 (2024) | 10.1088/1361-6382/ad42fb | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Pointing-related displacement noises are crucial in space-based gravitational
wave detectors, where point-ahead angle control of transmitted laser beams may
contribute significantly. For TianQin that features a geocentric concept, the
circular high orbit design with a nearly fixed constellation plane gives rise
to small variations of the point-ahead angles within $\pm 25$ nrad in-plane and
$\pm 10$ nrad off-plane, in addition to a static bias of 23 $\mu$rad
predominantly within the constellation plane. Accordingly, TianQin may adopt
fixed-value compensation for the point-ahead angles and absorb the small and
slow variations into the pointing biases. To assess the in-principle
feasibility, the far-field tilt-to-length (TTL) coupling effect is discussed,
and preliminary requirements on far-field wavefront quality are derived, which
have taken into account of TTL noise subtraction capability in post processing.
The proposed strategy has benefits in simplifying the interferometry design,
payload operation, and TTL noise mitigation for TianQin.
| [
{
"created": "Sun, 4 Feb 2024 07:55:25 GMT",
"version": "v1"
}
] | 2024-06-21 | [
[
"Wang",
"Dezhi",
""
],
[
"Zhang",
"Xuefeng",
""
],
[
"Duan",
"Hui-Zong",
""
]
] | Pointing-related displacement noises are crucial in space-based gravitational wave detectors, where point-ahead angle control of transmitted laser beams may contribute significantly. For TianQin that features a geocentric concept, the circular high orbit design with a nearly fixed constellation plane gives rise to small variations of the point-ahead angles within $\pm 25$ nrad in-plane and $\pm 10$ nrad off-plane, in addition to a static bias of 23 $\mu$rad predominantly within the constellation plane. Accordingly, TianQin may adopt fixed-value compensation for the point-ahead angles and absorb the small and slow variations into the pointing biases. To assess the in-principle feasibility, the far-field tilt-to-length (TTL) coupling effect is discussed, and preliminary requirements on far-field wavefront quality are derived, which have taken into account of TTL noise subtraction capability in post processing. The proposed strategy has benefits in simplifying the interferometry design, payload operation, and TTL noise mitigation for TianQin. |
1210.4012 | Jiang Qing-Quan | Qing-Quan Jiang | Revisit emission spectrum and entropy quantum of the
Reissner-Nordstr\"{o}m black hole | 7 pages | Eur. Phys. J. C72 (2012) 2086 | 10.1140/epjc/s10052-012-2086-y | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Banerjee and Majhi's recent work shows that black hole's emission spectrum
could be fully reproduced in the tunneling picture, where, as an intriguing
technique, the Kruskal extension was introduced to connect the left and right
modes inside and outside the horizon. Some attempt, as an extension, was
focused on producing the Hawking emission spectrum of the (charged)
Reissner-Nordstr\"{o}m black hole in the Banerjee-Majhi's treatment.
Unfortunately, the Kruskal extension in their observation was so badly defined
that the ingoing mode was classically forbidden traveling towards the center of
black hole, but could quantum tunnel across the horizon with the probability
$\Gamma=e^{-\pi \omega_0/\kappa_+}$. This tunneling picture is unphysical. With
this point as a central motivation, in this paper we first introduce such a
suitable Kruskal extension for the (charged) Reissner-Nordstr\"{o}m black hole
that a perfect tunneling picture can be provided during the charged particle's
emission. Then, under the new Kruskal extension, we revisit the Hawking
emission spectrum and entropy spectroscopy as tunneling from the charged black
hole. The result shows that the tunneling method is so universally robust that
the Hawking blackbody emission spectrum from a charged black hole can be well
reproduced in the tunneling mechanism, and its induced entropy quantum is a
much better approximation for the forthcoming quantum gravity theory.
| [
{
"created": "Mon, 15 Oct 2012 12:51:25 GMT",
"version": "v1"
}
] | 2015-06-11 | [
[
"Jiang",
"Qing-Quan",
""
]
] | Banerjee and Majhi's recent work shows that black hole's emission spectrum could be fully reproduced in the tunneling picture, where, as an intriguing technique, the Kruskal extension was introduced to connect the left and right modes inside and outside the horizon. Some attempt, as an extension, was focused on producing the Hawking emission spectrum of the (charged) Reissner-Nordstr\"{o}m black hole in the Banerjee-Majhi's treatment. Unfortunately, the Kruskal extension in their observation was so badly defined that the ingoing mode was classically forbidden traveling towards the center of black hole, but could quantum tunnel across the horizon with the probability $\Gamma=e^{-\pi \omega_0/\kappa_+}$. This tunneling picture is unphysical. With this point as a central motivation, in this paper we first introduce such a suitable Kruskal extension for the (charged) Reissner-Nordstr\"{o}m black hole that a perfect tunneling picture can be provided during the charged particle's emission. Then, under the new Kruskal extension, we revisit the Hawking emission spectrum and entropy spectroscopy as tunneling from the charged black hole. The result shows that the tunneling method is so universally robust that the Hawking blackbody emission spectrum from a charged black hole can be well reproduced in the tunneling mechanism, and its induced entropy quantum is a much better approximation for the forthcoming quantum gravity theory. |
gr-qc/0107103 | Maurizio Gasperini | E. Coccia, M. Gasperini and C. Ungarelli | Sensitivity of spherical gravitational-wave detectors to a stochastic
background of non-relativistic scalar radiation | four pages, latex | Phys.Rev.D65:067101,2002 | 10.1103/PhysRevD.65.067101 | BA-TH/01-421 | gr-qc astro-ph hep-th | null | We analyze the signal-to-noise ratio for a relic background of scalar
gravitational radiation composed of massive, non-relativistic particles,
interacting with the monopole mode of two resonant spherical detectors. We find
that the possible signal is enhanced with respect to the differential mode of
the interferometric detectors. This enhancement is due to: {\rm (a)} the
absence of the signal suppression, for non-relativistic scalars, with respect
to a background of massless particles, and {\rm (b)} for flat enough spectra, a
growth of the signal with the observation time faster than for a massless
stochastic background.
| [
{
"created": "Tue, 31 Jul 2001 14:55:10 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"Coccia",
"E.",
""
],
[
"Gasperini",
"M.",
""
],
[
"Ungarelli",
"C.",
""
]
] | We analyze the signal-to-noise ratio for a relic background of scalar gravitational radiation composed of massive, non-relativistic particles, interacting with the monopole mode of two resonant spherical detectors. We find that the possible signal is enhanced with respect to the differential mode of the interferometric detectors. This enhancement is due to: {\rm (a)} the absence of the signal suppression, for non-relativistic scalars, with respect to a background of massless particles, and {\rm (b)} for flat enough spectra, a growth of the signal with the observation time faster than for a massless stochastic background. |
gr-qc/0605071 | Elizabeth Wickham | E.D.L.Wickham, A.Stroeer, and A.Vecchio | A Markov Chain Monte Carlo approach to the study of massive black hole
binary systems with LISA | submitted to cqg as GWDAW-10 conference proceedings, 10 pages, 4
figures, some changes to plots and numerical details | Class.Quant.Grav. 23 (2006) S819-S828 | 10.1088/0264-9381/23/19/S20 | null | gr-qc astro-ph | null | The Laser Interferometer Space Antenna (LISA) will produce a data stream
containing a vast number of overlapping sources: from strong signals generated
by the coalescence of massive black hole binary systems to much weaker
radiation form sub-stellar mass compact binaries and extreme-mass ratio
inspirals. It has been argued that the observation of weak signals could be
hampered by the presence of loud ones and that they first need to be removed to
allow such observations. Here we consider a different approach in which sources
are studied simultaneously within the framework of Bayesian inference. We
investigate the simplified case in which the LISA data stream contains
radiation from a massive black hole binary system superimposed over a (weaker)
quasi-monochromatic waveform generated by a white dwarf binary. We derive the
posterior probability density function of the model parameters using an
automatic Reversible Jump Markov Chain Monte Carlo algorithm (RJMCMC). We show
that the information about the sources and noise are retrieved at the expected
level of accuracy without the need of removing the stronger signal. Our
analysis suggests that this approach is worth pursuing further and should be
considered for the actual analysis of the LISA data.
| [
{
"created": "Thu, 11 May 2006 13:59:47 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Jun 2006 11:28:29 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Wickham",
"E. D. L.",
""
],
[
"Stroeer",
"A.",
""
],
[
"Vecchio",
"A.",
""
]
] | The Laser Interferometer Space Antenna (LISA) will produce a data stream containing a vast number of overlapping sources: from strong signals generated by the coalescence of massive black hole binary systems to much weaker radiation form sub-stellar mass compact binaries and extreme-mass ratio inspirals. It has been argued that the observation of weak signals could be hampered by the presence of loud ones and that they first need to be removed to allow such observations. Here we consider a different approach in which sources are studied simultaneously within the framework of Bayesian inference. We investigate the simplified case in which the LISA data stream contains radiation from a massive black hole binary system superimposed over a (weaker) quasi-monochromatic waveform generated by a white dwarf binary. We derive the posterior probability density function of the model parameters using an automatic Reversible Jump Markov Chain Monte Carlo algorithm (RJMCMC). We show that the information about the sources and noise are retrieved at the expected level of accuracy without the need of removing the stronger signal. Our analysis suggests that this approach is worth pursuing further and should be considered for the actual analysis of the LISA data. |
gr-qc/9906014 | Steven L. Liebling | Steven L. Liebling | Static Gravitational Global Monopoles | 4 pages, 6 figures | Phys.Rev. D61 (2000) 024030 | 10.1103/PhysRevD.61.024030 | null | gr-qc hep-th | null | Static solutions in spherical symmetry are found for gravitating global
monopoles. Regular solutions lacking a horizon are found for $\eta <
1/\sqrt{8\pi}$, where $\eta$ is the scale of symmetry breaking. Apparently
regular solutions with a horizon are found for $1/\sqrt{8\pi} \le \eta \alt
\sqrt{3/8\pi}$. Though they have a horizon, they are not Schwarzschild. The
solution for $\eta = 1/\sqrt{8\pi}$ is argued to have a horizon at infinity.
The failure to find static solutions for $\eta > \sqrt{3/8\pi} \approx 0.3455$
is consistent with findings that topological inflation begins at $\eta \approx
0.33$.
| [
{
"created": "Thu, 3 Jun 1999 19:36:44 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Liebling",
"Steven L.",
""
]
] | Static solutions in spherical symmetry are found for gravitating global monopoles. Regular solutions lacking a horizon are found for $\eta < 1/\sqrt{8\pi}$, where $\eta$ is the scale of symmetry breaking. Apparently regular solutions with a horizon are found for $1/\sqrt{8\pi} \le \eta \alt \sqrt{3/8\pi}$. Though they have a horizon, they are not Schwarzschild. The solution for $\eta = 1/\sqrt{8\pi}$ is argued to have a horizon at infinity. The failure to find static solutions for $\eta > \sqrt{3/8\pi} \approx 0.3455$ is consistent with findings that topological inflation begins at $\eta \approx 0.33$. |
2308.10212 | \"Ozg\"ur \"Okc\"u | Zeynep \c{C}oker, \"Ozg\"ur \"Okc\"u, Ekrem Aydiner | Modified Friedmann equations from fractional entropy | 16 pages, 2 figures. References added. Minor corrections | EPL 143 (2023) 59001 | 10.1209/0295-5075/acf158 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | Based on the fractional black hole entropy (Jalalzadeh S. et al., Eur. Phys.
J. C, 81 (2021) 632), we derive the modified Friedmann equations from two
different frameworks. First, we consider the modifications of Friedmann
equations from the first law of thermodynamics at the apparent horizon. We show
that the generalized second law (GSL) of thermodynamics always holds in a
region bounded by the apparent horizon. Then, we obtain Friedmann equations
from Verlinde's entropic gravity framework. We also compute the fractional
corrections to the deceleration parameter $q$ in the flat case $k=0$ for both
frameworks. Furthermore, we consider the time to reach the initial singularity
for the two frameworks. The results indicate that the initial singularity is
accessible for both frameworks. However, fractional effects may provide a
constraint on the equation of state parameter in the entropic gravity scenario
since the time is imaginary for $-2/3\alpha<\omega<-1/3$.
| [
{
"created": "Sun, 20 Aug 2023 09:45:00 GMT",
"version": "v1"
},
{
"created": "Tue, 5 Sep 2023 12:51:14 GMT",
"version": "v2"
}
] | 2023-09-06 | [
[
"Çoker",
"Zeynep",
""
],
[
"Ökcü",
"Özgür",
""
],
[
"Aydiner",
"Ekrem",
""
]
] | Based on the fractional black hole entropy (Jalalzadeh S. et al., Eur. Phys. J. C, 81 (2021) 632), we derive the modified Friedmann equations from two different frameworks. First, we consider the modifications of Friedmann equations from the first law of thermodynamics at the apparent horizon. We show that the generalized second law (GSL) of thermodynamics always holds in a region bounded by the apparent horizon. Then, we obtain Friedmann equations from Verlinde's entropic gravity framework. We also compute the fractional corrections to the deceleration parameter $q$ in the flat case $k=0$ for both frameworks. Furthermore, we consider the time to reach the initial singularity for the two frameworks. The results indicate that the initial singularity is accessible for both frameworks. However, fractional effects may provide a constraint on the equation of state parameter in the entropic gravity scenario since the time is imaginary for $-2/3\alpha<\omega<-1/3$. |
1407.7746 | Benjamin Bahr | Benjamin Bahr | On background-independent renormalization of spin foam models | 23 pages, 12 figures, updated references | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this article we discuss an implementation of renormalization group ideas
to spin foam models, where there is no a priori length scale with which to
define the flow. In the context of the continuum limit of these models, we show
how the notion of cylindrical consistency of path integral measures gives a
natural analogue of Wilson's RG flow equations for background-independent
systems. We discuss the conditions for the continuum measures to be
diffeomorphism-invariant, and consider both exact and approximate examples.
| [
{
"created": "Tue, 29 Jul 2014 14:53:52 GMT",
"version": "v1"
},
{
"created": "Tue, 9 Sep 2014 14:53:35 GMT",
"version": "v2"
}
] | 2014-09-10 | [
[
"Bahr",
"Benjamin",
""
]
] | In this article we discuss an implementation of renormalization group ideas to spin foam models, where there is no a priori length scale with which to define the flow. In the context of the continuum limit of these models, we show how the notion of cylindrical consistency of path integral measures gives a natural analogue of Wilson's RG flow equations for background-independent systems. We discuss the conditions for the continuum measures to be diffeomorphism-invariant, and consider both exact and approximate examples. |
1401.4815 | Torsten Asselmeyer-Maluga | T. Asselmeyer-Maluga and J. Krol | Inflation and topological phase transition driven by exotic smoothness | 21 pages, no figures, iopart styla, accepted in Advances in High
Energy Physics, special issue "Experimental Tests of Quantum Gravity and
Exotic Quantum Field Theory Effects (QGEQ)" | null | null | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we will discuss a model which describes the cause of inflation
by a topological transition. The guiding principle is the choice of an exotic
smoothness structure for the space-time. Here we consider a space-time with
topology $S^{3}\times\mathbb{R}$. In case of an exotic $S^{3}\times\mathbb{R}$,
there is a change in the spatial topology from a 3-sphere to a homology
3-sphere which can carry a hyperbolic structure. From the physical point of
view, we will discuss the path integral for the Einstein-Hilbert action with
respect to a decomposition of the space-time. The inclusion of the boundary
terms produces fermionic contributions to the partition function. The
expectation value of an area (with respect to some surface) shows an
exponential increase, i.e. we obtain inflationary behavior. We will calculate
the amount of this increase to be a topological invariant. Then we will
describe this transition by an effective model, the Starobinski or $R^{2}$
model which is consistent with the current measurement of the Planck satellite.
The spectral index and other observables are also calculated. Finally we obtain
a realistic cosmological constant.
| [
{
"created": "Mon, 20 Jan 2014 07:49:51 GMT",
"version": "v1"
}
] | 2014-01-21 | [
[
"Asselmeyer-Maluga",
"T.",
""
],
[
"Krol",
"J.",
""
]
] | In this paper we will discuss a model which describes the cause of inflation by a topological transition. The guiding principle is the choice of an exotic smoothness structure for the space-time. Here we consider a space-time with topology $S^{3}\times\mathbb{R}$. In case of an exotic $S^{3}\times\mathbb{R}$, there is a change in the spatial topology from a 3-sphere to a homology 3-sphere which can carry a hyperbolic structure. From the physical point of view, we will discuss the path integral for the Einstein-Hilbert action with respect to a decomposition of the space-time. The inclusion of the boundary terms produces fermionic contributions to the partition function. The expectation value of an area (with respect to some surface) shows an exponential increase, i.e. we obtain inflationary behavior. We will calculate the amount of this increase to be a topological invariant. Then we will describe this transition by an effective model, the Starobinski or $R^{2}$ model which is consistent with the current measurement of the Planck satellite. The spectral index and other observables are also calculated. Finally we obtain a realistic cosmological constant. |
gr-qc/0412036 | Abd El Fady Morcos | A.B.Morcos | Temperature Fluctuation and an Expected Limit of Hubble Parameter in the
Self-Consistent Model | 8 pages, Latex file | J.Korean Astron.Soc.39:81,2006 | 10.5303/JKAS.2006.39.4.081 | null | gr-qc | null | The temperature gradient of microwave background radiation (CMBR) is
calculated in the Self Consistent Model. An expected values for Hubble
parameter have been presented in two different cases. In the first case the
temperature is treated as a function of time only, while in the other one the
temperature depends on relaxation of isotropy condition in the self-consistent
model and the assumption that the universe expands adiabatically. The COBE's or
WMAP's fluctuations in temperature of CMBR may be used to predict a value for
Hubble parameter.
| [
{
"created": "Wed, 8 Dec 2004 15:18:12 GMT",
"version": "v1"
}
] | 2017-01-18 | [
[
"Morcos",
"A. B.",
""
]
] | The temperature gradient of microwave background radiation (CMBR) is calculated in the Self Consistent Model. An expected values for Hubble parameter have been presented in two different cases. In the first case the temperature is treated as a function of time only, while in the other one the temperature depends on relaxation of isotropy condition in the self-consistent model and the assumption that the universe expands adiabatically. The COBE's or WMAP's fluctuations in temperature of CMBR may be used to predict a value for Hubble parameter. |
2110.07675 | Marcelo J. Reboucas | N.A. Lemos, D. M\"uller, M.J. Reboucas | Probing spatial orientability of Friedmann--Robertson--Walker spatially
flat spacetime | 15 pages, 3 figures, 2 tables; V2: 29 pages, clarification of
orientability indicator added. New references included. Misprints corrected.
Versions to appear in Phys. Rev. D (2022). arXiv admin note: text overlap
with arXiv:2009.04071 | null | 10.1103/PhysRevD.106.023528 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | One important global topological property of a spacetime manifold is
orientability. It is widely believed that spatial orientability can only be
tested by global journeys around the Universe to check for
orientation-reversing closed paths. Since such global journeys are not
feasible, theoretical arguments that combine universality of physical
experiments with local arrow of time, CP violation and CPT invariance are
usually offered to support the choosing of time- and space-orientable spacetime
manifolds. The nonexistence of globally defined spinor fields on a
non-orientable spacetime is another theoretical argument for orientability.
However, it is conceivable that orientability can be put to test by local
physical effects. In this paper, we show that it is possible to locally access
spatial orientability of a spatially flat Friedmann--Robertson-Walker spacetime
through quantum vacuum electromagnestic fluctuations. We argue that a putative
non-orientability of the spatial sections of spatially flat FRW spacetime can
be ascertained by the study of the stochastic motions of a charged particle or
a point electric dipole under quantum vacuum electromagnetic fluctuations. In
particular, the stochastic motions of a dipole permit the recognition of a
presumed non-orientability of $3-$space in itself.
| [
{
"created": "Thu, 14 Oct 2021 19:17:23 GMT",
"version": "v1"
},
{
"created": "Thu, 14 Jul 2022 16:39:40 GMT",
"version": "v2"
}
] | 2022-08-17 | [
[
"Lemos",
"N. A.",
""
],
[
"Müller",
"D.",
""
],
[
"Reboucas",
"M. J.",
""
]
] | One important global topological property of a spacetime manifold is orientability. It is widely believed that spatial orientability can only be tested by global journeys around the Universe to check for orientation-reversing closed paths. Since such global journeys are not feasible, theoretical arguments that combine universality of physical experiments with local arrow of time, CP violation and CPT invariance are usually offered to support the choosing of time- and space-orientable spacetime manifolds. The nonexistence of globally defined spinor fields on a non-orientable spacetime is another theoretical argument for orientability. However, it is conceivable that orientability can be put to test by local physical effects. In this paper, we show that it is possible to locally access spatial orientability of a spatially flat Friedmann--Robertson-Walker spacetime through quantum vacuum electromagnestic fluctuations. We argue that a putative non-orientability of the spatial sections of spatially flat FRW spacetime can be ascertained by the study of the stochastic motions of a charged particle or a point electric dipole under quantum vacuum electromagnetic fluctuations. In particular, the stochastic motions of a dipole permit the recognition of a presumed non-orientability of $3-$space in itself. |
0808.0956 | Sergei Slobodov | Sergei Slobodov | Unwrapping Closed Timelike Curves | 29 pages, 9 figures | Found.Phys.38:1082-1109,2008 | 10.1007/s10701-008-9253-x | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Closed timelike curves (CTCs) appear in many solutions of the Einstein
equation, even with reasonable matter sources. These solutions appear to
violate causality and so are considered problematic. Since CTCs reflect the
global properties of a spacetime, one can attempt to change its topology,
without changing its geometry, in such a way that the former CTCs are no longer
closed in the new spacetime. This procedure is informally known as unwrapping.
However, changes in global identifications tend to lead to local effects, and
unwrapping is no exception, as it introduces a special kind of singularity,
called quasi-regular. This "unwrapping" singularity is similar to the string
singularities. We give two examples of unwrapping of essentially 2+1
dimensional spacetimes with CTCs, the Gott spacetime and the Godel universe. We
show that the unwrapped Gott spacetime, while singular, is at least devoid of
CTCs. In contrast, the unwrapped Godel spacetime still contains CTCs through
every point. A "multiple unwrapping" procedure is devised to remove the
remaining circular CTCs. We conclude that, based on the two spacetimes we
investigated, CTCs appearing in the solutions of the Einstein equation are not
simply a mathematical artifact of coordinate identifications, but are indeed a
necessary consequence of General Relativity, provided only that we demand these
solutions do not possess naked quasi-regular singularities.
| [
{
"created": "Thu, 7 Aug 2008 05:19:25 GMT",
"version": "v1"
}
] | 2008-12-18 | [
[
"Slobodov",
"Sergei",
""
]
] | Closed timelike curves (CTCs) appear in many solutions of the Einstein equation, even with reasonable matter sources. These solutions appear to violate causality and so are considered problematic. Since CTCs reflect the global properties of a spacetime, one can attempt to change its topology, without changing its geometry, in such a way that the former CTCs are no longer closed in the new spacetime. This procedure is informally known as unwrapping. However, changes in global identifications tend to lead to local effects, and unwrapping is no exception, as it introduces a special kind of singularity, called quasi-regular. This "unwrapping" singularity is similar to the string singularities. We give two examples of unwrapping of essentially 2+1 dimensional spacetimes with CTCs, the Gott spacetime and the Godel universe. We show that the unwrapped Gott spacetime, while singular, is at least devoid of CTCs. In contrast, the unwrapped Godel spacetime still contains CTCs through every point. A "multiple unwrapping" procedure is devised to remove the remaining circular CTCs. We conclude that, based on the two spacetimes we investigated, CTCs appearing in the solutions of the Einstein equation are not simply a mathematical artifact of coordinate identifications, but are indeed a necessary consequence of General Relativity, provided only that we demand these solutions do not possess naked quasi-regular singularities. |
1805.05959 | Giuseppe Fanizza | Giuseppe Fanizza, Jaiyul Yoo, Sang Gyu Biern (Zurich) | Non-linear general relativistic effects in the observed redshift | 44 pages, 1 figure, Version published in JCAP | JCAP 09 (2018) 037 | 10.1088/1475-7516/2018/09/037 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present the second-order expression for the observed redshift, accounting
for all the relativistic effects from the light propagation and from the frame
change at the observer and the source positions. We derive the generic
gauge-transformation law that any observable quantities should satisfy, and we
verify our second-order expression for the observed redshift by explicitly
checking its gauge transformation property. This is the first time an explicit
verification is made for the second-order calculations of observable
quantities. We present our results in popular gauge choices for easy use and
discuss the origin of disagreements in previous calculations.
| [
{
"created": "Tue, 15 May 2018 18:00:03 GMT",
"version": "v1"
},
{
"created": "Tue, 25 Sep 2018 12:33:11 GMT",
"version": "v2"
}
] | 2018-09-26 | [
[
"Fanizza",
"Giuseppe",
"",
"Zurich"
],
[
"Yoo",
"Jaiyul",
"",
"Zurich"
],
[
"Biern",
"Sang Gyu",
"",
"Zurich"
]
] | We present the second-order expression for the observed redshift, accounting for all the relativistic effects from the light propagation and from the frame change at the observer and the source positions. We derive the generic gauge-transformation law that any observable quantities should satisfy, and we verify our second-order expression for the observed redshift by explicitly checking its gauge transformation property. This is the first time an explicit verification is made for the second-order calculations of observable quantities. We present our results in popular gauge choices for easy use and discuss the origin of disagreements in previous calculations. |
gr-qc/0601071 | Sergei Kopeikin | Sergei M. Kopeikin (University of Missouri-Columbia, USA) and Wei-Tou
Ni (The Purple Mountain Observatory, Nanjing, China) | Laser Ranging Delay in the Bi-Metric Theory of Gravity | 6 pages, figure and text improved. To appear in: Proceedings of the
359th WE-Heraeus Seminar on "Lasers, Clocks, and Drag-Free: Technologies for
Future Exploration in Space and Tests of Gravity"}, ZARM, Bremen, Germany,
May 30-June 1, 2005 | null | null | null | gr-qc | null | We introduce a linearized bi-metric theory of gravity with two metrics. The
metric g_{ab} describes null hypersurfaces of the gravitational field while
light moves on null hypersurfaces of the optical metric \bar{g}_{ab}.
Bi-metrism naturally arises in vector-tensor theories with matter being
non-minimally coupled to gravity via long-range vector field. We derive
explicit Lorentz-invariant solution for a light ray propagating in space-time
of the bi-metric theory and disentangle relativistic effects associated with
the two metrics. This anlysis can be valuable for future spaceborne laser
missions ASTROD and LATOR dedicated to map various relativistic gravity
parameters in the solar system to unparalleled degree of accuracy.
| [
{
"created": "Wed, 18 Jan 2006 01:06:26 GMT",
"version": "v1"
},
{
"created": "Thu, 2 Mar 2006 01:14:46 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Kopeikin",
"Sergei M.",
"",
"University of Missouri-Columbia, USA"
],
[
"Ni",
"Wei-Tou",
"",
"The Purple Mountain Observatory, Nanjing, China"
]
] | We introduce a linearized bi-metric theory of gravity with two metrics. The metric g_{ab} describes null hypersurfaces of the gravitational field while light moves on null hypersurfaces of the optical metric \bar{g}_{ab}. Bi-metrism naturally arises in vector-tensor theories with matter being non-minimally coupled to gravity via long-range vector field. We derive explicit Lorentz-invariant solution for a light ray propagating in space-time of the bi-metric theory and disentangle relativistic effects associated with the two metrics. This anlysis can be valuable for future spaceborne laser missions ASTROD and LATOR dedicated to map various relativistic gravity parameters in the solar system to unparalleled degree of accuracy. |
1102.0385 | Farid Ya. Khalili | F.Ya.Khalili | Pass-through Mach-Zehnder topologies for macroscopic quantum
measurements | 11 pages, 9 figures | Phys.Rev.D83:122001,2011 | 10.1103/PhysRevD.83.122001 | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Several relatively small-scale experimental setups aimed on prototyping of
future laser gravitational-wave detectors and testing of new methods of quantum
measurements with macroscopic mechanical objects, are under development now. In
these devices, not devoted directly to the gravitational-wave detection,
Mach-Zehnder interferometer with pass-through Fabry-Perot cavities in the arms
can be used instead of the standard Michelson/Fabry-Perot one. The advantage of
this topology is that it does not contain high-reflectivity end mirrors with
multilayer coatings, which Brownian noise could constitute the major part of
the noise budget of the Michelson/Fabry-Perot interferometers.
We consider here two variants of this topology: the "ordinary" position meter
scheme, and a new variant of the quantum speed meter.
| [
{
"created": "Wed, 2 Feb 2011 08:56:57 GMT",
"version": "v1"
}
] | 2011-06-13 | [
[
"Khalili",
"F. Ya.",
""
]
] | Several relatively small-scale experimental setups aimed on prototyping of future laser gravitational-wave detectors and testing of new methods of quantum measurements with macroscopic mechanical objects, are under development now. In these devices, not devoted directly to the gravitational-wave detection, Mach-Zehnder interferometer with pass-through Fabry-Perot cavities in the arms can be used instead of the standard Michelson/Fabry-Perot one. The advantage of this topology is that it does not contain high-reflectivity end mirrors with multilayer coatings, which Brownian noise could constitute the major part of the noise budget of the Michelson/Fabry-Perot interferometers. We consider here two variants of this topology: the "ordinary" position meter scheme, and a new variant of the quantum speed meter. |
1706.04361 | Riccardo Moriconi | Riccardo Moriconi and Giovanni Montani | Behavior of the Universe anisotropy in a big-bounce cosmology | 20 pages, 7 figures | null | 10.1103/PhysRevD.95.123533 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the classical and quantum behavior of a Bianchi I model in the
presence of a stiff matter contribution when the Vilenkin interpretation of the
wave function of the Universe is taken into account. We study its evolution in
the so-called polymer representation of quantum mechanics, in order to
characterize the modifications that a discrete nature in the isotropic variable
of the Universe induces on the morphology of the cosmological singularity. We
demonstrate that in such a model the Big-Bang singularity is removed at a
semiclassical level in favor of a Big-Bounce when a lattice on the isotropic
variable is considered. Furthermore, the analysis of the mean values on the
quantum degrees of freedom, \textit{i.e} the variables $\beta_{+},\beta_{-}$ in
the Misner picture, and the investigation on the evolution of the wave packets
show how the typical diverging behavior associated to the anisotropies of the
Universe in proximity of the initial singularity disappears in our polymer
modified scheme. Indeed, the anisotropies remain finite across the Big-Bounce
and they assume a value that depends on the initial conditions fixed far from
the turning point. Finally, we demonstrate that the proposed scenario can be
extended, with a suitable choice of the configuration parameters, to the
Bianchi IX cosmology and therefore it can be regarded as a paradigm for the
generic cosmological model.
| [
{
"created": "Wed, 14 Jun 2017 08:34:54 GMT",
"version": "v1"
}
] | 2017-08-02 | [
[
"Moriconi",
"Riccardo",
""
],
[
"Montani",
"Giovanni",
""
]
] | We investigate the classical and quantum behavior of a Bianchi I model in the presence of a stiff matter contribution when the Vilenkin interpretation of the wave function of the Universe is taken into account. We study its evolution in the so-called polymer representation of quantum mechanics, in order to characterize the modifications that a discrete nature in the isotropic variable of the Universe induces on the morphology of the cosmological singularity. We demonstrate that in such a model the Big-Bang singularity is removed at a semiclassical level in favor of a Big-Bounce when a lattice on the isotropic variable is considered. Furthermore, the analysis of the mean values on the quantum degrees of freedom, \textit{i.e} the variables $\beta_{+},\beta_{-}$ in the Misner picture, and the investigation on the evolution of the wave packets show how the typical diverging behavior associated to the anisotropies of the Universe in proximity of the initial singularity disappears in our polymer modified scheme. Indeed, the anisotropies remain finite across the Big-Bounce and they assume a value that depends on the initial conditions fixed far from the turning point. Finally, we demonstrate that the proposed scenario can be extended, with a suitable choice of the configuration parameters, to the Bianchi IX cosmology and therefore it can be regarded as a paradigm for the generic cosmological model. |
1505.00205 | Michael Coughlin | Michael Coughlin and Patrick Meyers and Shivaraj Kandhasamy and Eric
Thrane and Nelson Christensen | Chasing 5-sigma: Prospects for searches for long-duration
gravitational-waves without time slides | null | Phys. Rev. D 92, 043007 (2015) | 10.1103/PhysRevD.92.043007 | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The detection of unmodeled gravitational-wave bursts by ground-based
interferometric gravitational-wave detectors is a major goal for the advanced
detector era. These searches are commonly cast as pattern recognition problems,
where the goal is to identify statistically significant clusters in
spectrograms of strain power when the precise signal morphology is unknown. In
previous work, we have introduced a clustering algorithm referred to as
"seedless clustering," and shown that it is a powerful tool for detecting weak
long-lived (10-1000s) signals in background. However, as the algorithm is
currently conceived, in order to carry out an all-sky search on a $\approx$
year of data, significant computational resources may be required in order to
carry out background estimation. Alternatively, some of the sensitivity of the
search must be sacrificed to control computational costs. The sensitivity of
the algorithm is limited by the amount of computing resources due to the
requirement of performing background studies to assign significance in
gravitational-wave searches. In this paper, we present an analytic method for
estimating the background generated by the seedless clustering algorithm and
compare the performance to both Monte Carlo Gaussian noise and time-shifted
gravitational-wave data from a week of LIGO's 5th Science Run. We demonstrate
qualitative agreement between the model and measured distributions and argue
that the approximation will be useful to supplement conventional background
estimation techniques for advanced detector searches for long-duration
gravitational-wave transients.
| [
{
"created": "Fri, 1 May 2015 15:46:32 GMT",
"version": "v1"
}
] | 2015-08-26 | [
[
"Coughlin",
"Michael",
""
],
[
"Meyers",
"Patrick",
""
],
[
"Kandhasamy",
"Shivaraj",
""
],
[
"Thrane",
"Eric",
""
],
[
"Christensen",
"Nelson",
""
]
] | The detection of unmodeled gravitational-wave bursts by ground-based interferometric gravitational-wave detectors is a major goal for the advanced detector era. These searches are commonly cast as pattern recognition problems, where the goal is to identify statistically significant clusters in spectrograms of strain power when the precise signal morphology is unknown. In previous work, we have introduced a clustering algorithm referred to as "seedless clustering," and shown that it is a powerful tool for detecting weak long-lived (10-1000s) signals in background. However, as the algorithm is currently conceived, in order to carry out an all-sky search on a $\approx$ year of data, significant computational resources may be required in order to carry out background estimation. Alternatively, some of the sensitivity of the search must be sacrificed to control computational costs. The sensitivity of the algorithm is limited by the amount of computing resources due to the requirement of performing background studies to assign significance in gravitational-wave searches. In this paper, we present an analytic method for estimating the background generated by the seedless clustering algorithm and compare the performance to both Monte Carlo Gaussian noise and time-shifted gravitational-wave data from a week of LIGO's 5th Science Run. We demonstrate qualitative agreement between the model and measured distributions and argue that the approximation will be useful to supplement conventional background estimation techniques for advanced detector searches for long-duration gravitational-wave transients. |
gr-qc/9709008 | Alexander L. Gromov | Alexander Gromov (St-Petersburg State Thechnical University, Russia) | Singularities, initial and boundary problems for the Tolman-Bondi model | LaTeX,7 pages | null | null | null | gr-qc | null | Boundary problem for Tolman-Bondi model is formulated. One-to-one
correspondence between singularities hypersurfaces and initial conditions of
the Tolman-Bondi model is constructed.
| [
{
"created": "Wed, 3 Sep 1997 19:44:17 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Gromov",
"Alexander",
"",
"St-Petersburg State Thechnical University, Russia"
]
] | Boundary problem for Tolman-Bondi model is formulated. One-to-one correspondence between singularities hypersurfaces and initial conditions of the Tolman-Bondi model is constructed. |
1205.4016 | Benjamin C. Harms | Peter L. Biermann and Benjamin C. Harms | A graviton statistics approach to dark energy, inflation and black holes | 75 pages, 7 figures, additional text to clarify key points,
typographical errors corrected, additional references, the model and its
predictions are unchanged | null | null | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive two new equations of quantum gravity and combine them with
reinterpretations of previously proposed concepts of dark energy, inflation and
black holes into a theory which may be a first step toward a comprehensive
description of all three phenomena. The resulting theory also predicts new
tests which can be experimentally checked within just a few years. The two new
equations are : A) a creation equation to give stimulated emission for any
surface filled with gravitons, pulling energy from a background, and B) the
association of an outgoing soliton wave of gravitons, a "shell front" with a
large Lorentz factor derived from the uncertainties in both space and time.
These new equations are combined with the common notions of an all-pervasive
background of gravitons at the Planck limit, the "Planck sea"; the
identification of the thermodynamic limit with the emission of gravitons in a
"shell front", i.e. what is usually called the entropy of black holes is
identified with the outgoing gravitons; the concept of black holes as a
membrane full of gravitons at a large Lorentz factor, the "Planck shell"; the
emission of gravitons created in a "horizon shell" during inflation. These
equations result in stimulated emission of gravitons by the interaction with
the background, the "Planck sea", to describe dark energy, black holes, the
inflationary period of the universe, and the arrow of time. These proposals
lead to gravitational waves constituting dark energy. These waves should be
detectable within a few years with pulsar timing arrays. These gravitational
waves can be characterized as uncorrelated solitons, and should also be
detectable with ultra-high precision lunar laser ranging, as well as with
correspondingly precise clocks. The extremely high, but finite Lorentz factor
for signal propagation may be expected to have further consequences in particle
interactions.
| [
{
"created": "Thu, 17 May 2012 19:40:58 GMT",
"version": "v1"
},
{
"created": "Wed, 23 May 2012 19:39:37 GMT",
"version": "v2"
},
{
"created": "Fri, 10 Aug 2012 15:21:45 GMT",
"version": "v3"
},
{
"created": "Wed, 22 Aug 2012 22:21:07 GMT",
"version": "v4"
},
{
"created": "Wed, 13 Feb 2013 22:09:19 GMT",
"version": "v5"
}
] | 2013-02-15 | [
[
"Biermann",
"Peter L.",
""
],
[
"Harms",
"Benjamin C.",
""
]
] | We derive two new equations of quantum gravity and combine them with reinterpretations of previously proposed concepts of dark energy, inflation and black holes into a theory which may be a first step toward a comprehensive description of all three phenomena. The resulting theory also predicts new tests which can be experimentally checked within just a few years. The two new equations are : A) a creation equation to give stimulated emission for any surface filled with gravitons, pulling energy from a background, and B) the association of an outgoing soliton wave of gravitons, a "shell front" with a large Lorentz factor derived from the uncertainties in both space and time. These new equations are combined with the common notions of an all-pervasive background of gravitons at the Planck limit, the "Planck sea"; the identification of the thermodynamic limit with the emission of gravitons in a "shell front", i.e. what is usually called the entropy of black holes is identified with the outgoing gravitons; the concept of black holes as a membrane full of gravitons at a large Lorentz factor, the "Planck shell"; the emission of gravitons created in a "horizon shell" during inflation. These equations result in stimulated emission of gravitons by the interaction with the background, the "Planck sea", to describe dark energy, black holes, the inflationary period of the universe, and the arrow of time. These proposals lead to gravitational waves constituting dark energy. These waves should be detectable within a few years with pulsar timing arrays. These gravitational waves can be characterized as uncorrelated solitons, and should also be detectable with ultra-high precision lunar laser ranging, as well as with correspondingly precise clocks. The extremely high, but finite Lorentz factor for signal propagation may be expected to have further consequences in particle interactions. |
gr-qc/0605154 | Scott Pollack | Scott E Pollack and Robin Tuck Stebbins | Demonstration of the Zero-Crossing Phasemeter with a LISA Test-bed
Interferometer | find minor corrections in the CQG version | Class.Quant.Grav.23:4189-4200,2006 | 10.1088/0264-9381/23/12/014 | null | gr-qc | null | The Laser Interferometer Space Antenna (LISA) is being designed to detect and
study in detail gravitational waves from sources throughout the Universe such
as massive black hole binaries. The conceptual formulation of the LISA
space-borne gravitational wave detector is now well developed. The
interferometric measurements between the sciencecraft remain one of the most
important technological and scientific design areas for the mission.
Our work has concentrated on developing the interferometric technologies to
create a LISA-like optical signal and to measure the phase of that signal using
commercially available instruments. One of the most important goals of this
research is to demonstrate the LISA phase timing and phase reconstruction for a
LISA-like fringe signal, in the case of a high fringe rate and a low signal
level. We present current results of a test-bed interferometer designed to
produce an optical LISA-like fringe signal previously discussed in the
literature.
| [
{
"created": "Wed, 31 May 2006 19:31:49 GMT",
"version": "v1"
}
] | 2014-11-17 | [
[
"Pollack",
"Scott E",
""
],
[
"Stebbins",
"Robin Tuck",
""
]
] | The Laser Interferometer Space Antenna (LISA) is being designed to detect and study in detail gravitational waves from sources throughout the Universe such as massive black hole binaries. The conceptual formulation of the LISA space-borne gravitational wave detector is now well developed. The interferometric measurements between the sciencecraft remain one of the most important technological and scientific design areas for the mission. Our work has concentrated on developing the interferometric technologies to create a LISA-like optical signal and to measure the phase of that signal using commercially available instruments. One of the most important goals of this research is to demonstrate the LISA phase timing and phase reconstruction for a LISA-like fringe signal, in the case of a high fringe rate and a low signal level. We present current results of a test-bed interferometer designed to produce an optical LISA-like fringe signal previously discussed in the literature. |
1108.5760 | Jan Hlad\'ik | Jan Hladik, Zdenek Stuchlik | Photon and neutrino redshift in the field of braneworld compact stars | null | JCAP07(2011)012 | 10.1088/1475-7516/2011/07/012 | null | gr-qc astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study gravitational redshift of photons and neutrinos radiated by the
braneworld neutron or quark stars that are considered in the framework of the
simple model of the internal spacetime with uniform distribution of energy
density, and the external spacetime described by the Reissner-Nordstr\"{o}m
geometry characterized by the braneworld "tidal" charge $b$. For negative tidal
charges, the external spacetime is of the black-hole type, while for positive
tidal charges, the external spacetime can be of both black-hole and
naked-singularity type. We consider also extremely compact stars allowing
existence of trapped null geodesics in their interior. We assume radiation of
photons from the surface at radius $R$, neutrinos from the whole compact star
interior, and their motion along radial null geodesics of the spacetime. In
dependency on the compact stars parameters $b$ and $R$, the photon surface
redshift is related to the range of the neutrino internal redshift and the
signatures of the tidal charge and possible existence of extremely compact
stars are discussed. When both surface (photon) and internal (neutrino)
redshift are given by observations, both compact star parameters $R$ and $b$
can be determined in the framework of our simple model.
| [
{
"created": "Mon, 29 Aug 2011 21:29:39 GMT",
"version": "v1"
}
] | 2011-08-31 | [
[
"Hladik",
"Jan",
""
],
[
"Stuchlik",
"Zdenek",
""
]
] | We study gravitational redshift of photons and neutrinos radiated by the braneworld neutron or quark stars that are considered in the framework of the simple model of the internal spacetime with uniform distribution of energy density, and the external spacetime described by the Reissner-Nordstr\"{o}m geometry characterized by the braneworld "tidal" charge $b$. For negative tidal charges, the external spacetime is of the black-hole type, while for positive tidal charges, the external spacetime can be of both black-hole and naked-singularity type. We consider also extremely compact stars allowing existence of trapped null geodesics in their interior. We assume radiation of photons from the surface at radius $R$, neutrinos from the whole compact star interior, and their motion along radial null geodesics of the spacetime. In dependency on the compact stars parameters $b$ and $R$, the photon surface redshift is related to the range of the neutrino internal redshift and the signatures of the tidal charge and possible existence of extremely compact stars are discussed. When both surface (photon) and internal (neutrino) redshift are given by observations, both compact star parameters $R$ and $b$ can be determined in the framework of our simple model. |
0804.3944 | Nora Breton | Aaron V. B. Arellano (1), Nora Breton (2), Ricardo Garcia-Salcedo
(3),((1) Universidad Aut\'onoma del Estado de M\'exico, (2) Centro de
Investigaci\'on y de Estudios Avanzados del I.P.N., Mexico (3) CICATA-IPN,
Mexico) | Some properties of evolving wormhole geometries within nonlinear
electrodynamics | 13 pages, 3(ps) figures | Gen.Rel.Grav.41:2561-2578,2009 | 10.1007/s10714-009-0780-3 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we review some properties for the evolving wormhole solution of
Einstein equations coupled with nonlinear electrodynamics. We integrate the
geodesic equations in the effective geometry obeyed by photons; we check out
the weak field limit and find the traversability conditions. Then we analyze
the case when the lagrangian depends on two electromagnetic invariants and it
turns out that there is not a more general solution within the assumed
geometry.
| [
{
"created": "Thu, 24 Apr 2008 15:19:41 GMT",
"version": "v1"
}
] | 2010-01-08 | [
[
"Arellano",
"Aaron V. B.",
""
],
[
"Breton",
"Nora",
""
],
[
"Garcia-Salcedo",
"Ricardo",
""
]
] | In this paper we review some properties for the evolving wormhole solution of Einstein equations coupled with nonlinear electrodynamics. We integrate the geodesic equations in the effective geometry obeyed by photons; we check out the weak field limit and find the traversability conditions. Then we analyze the case when the lagrangian depends on two electromagnetic invariants and it turns out that there is not a more general solution within the assumed geometry. |
1604.00269 | Mindaugas Karciauskas Dr. | Mindaugas Kar\v{c}iauskas | Dynamical Analysis of Anisotropic Inflation | 17 pages, 2 figures | null | 10.1142/S0217732316400022 | null | gr-qc astro-ph.CO hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Inflaton coupling to a vector field via the $f^2(\phi)F_{\mu\nu}F^{\mu\nu}$
term is used in several contexts in the literature, such as to generate
primordial magnetic fields, to produce statistically anisotropic curvature
perturbation, to support anisotropic inflation and to circumvent the
$\eta$-problem. Here, I perform dynamical analysis of such a system allowing
for most general Bianchi I initial conditions. I also confirm the stability of
attractor equilibrium points in phase-space directions that had not been
investigated before.
| [
{
"created": "Thu, 31 Mar 2016 13:50:23 GMT",
"version": "v1"
},
{
"created": "Wed, 31 Aug 2016 18:40:15 GMT",
"version": "v2"
}
] | 2016-09-01 | [
[
"Karčiauskas",
"Mindaugas",
""
]
] | Inflaton coupling to a vector field via the $f^2(\phi)F_{\mu\nu}F^{\mu\nu}$ term is used in several contexts in the literature, such as to generate primordial magnetic fields, to produce statistically anisotropic curvature perturbation, to support anisotropic inflation and to circumvent the $\eta$-problem. Here, I perform dynamical analysis of such a system allowing for most general Bianchi I initial conditions. I also confirm the stability of attractor equilibrium points in phase-space directions that had not been investigated before. |
gr-qc/0507111 | Luc Blanchet | Luc Blanchet | General relativity and the spiral of compact binary stars | 8 pages, in "Images de la Physique 2005", eds. E. Falgarone et al.,
Editions du C.N.R.S., p. 51, 2005 (in French) | null | null | null | gr-qc | null | The theory of general relativity, which is extremely well verified by classic
tests in the solar system as well as by the radiation of the binary pulsar, is
one of the fundamental tools of nowadays astrophysics. It permits the
computation of the gravitational wave form emitted during the inspiral phase of
binary systems of neutron stars and black holes. Based on the so-called
post-Newtonian approximation (developped to high order), the prediction of
general relativity is used as a "template" for searching and analysing the
signals in the network of gravitational-wave detectors VIRGO/LIGO.
| [
{
"created": "Tue, 26 Jul 2005 18:12:30 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Blanchet",
"Luc",
""
]
] | The theory of general relativity, which is extremely well verified by classic tests in the solar system as well as by the radiation of the binary pulsar, is one of the fundamental tools of nowadays astrophysics. It permits the computation of the gravitational wave form emitted during the inspiral phase of binary systems of neutron stars and black holes. Based on the so-called post-Newtonian approximation (developped to high order), the prediction of general relativity is used as a "template" for searching and analysing the signals in the network of gravitational-wave detectors VIRGO/LIGO. |
1703.08655 | Bernard J. Carr | B. J. Carr | Quantum Black Holes as the Link Between Microphysics and Macrophysics | 9 pages, 7 figures, 2015 Karl Schwarzschild Meeting on Gravitational
Physics, eds. P. Nicolini, J. Mureika, M. Kaminski and M. Bleicher | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | There appears to be a duality between elementary particles, which span the
mass range below the Planck scale, and black holes, which span the mass range
range above it. In particular, the Black Hole Uncertainty Principle
Correspondence posits a smooth transition between the Compton and Schwarzschild
scales as a function of mass. This suggests that all black holes are in some
sense quantum, that elementary particles can be interpreted as sub-Planckian
black holes, and that there is a subtle connection between quantum and
classical physics.
| [
{
"created": "Sat, 25 Mar 2017 06:50:02 GMT",
"version": "v1"
}
] | 2017-03-28 | [
[
"Carr",
"B. J.",
""
]
] | There appears to be a duality between elementary particles, which span the mass range below the Planck scale, and black holes, which span the mass range range above it. In particular, the Black Hole Uncertainty Principle Correspondence posits a smooth transition between the Compton and Schwarzschild scales as a function of mass. This suggests that all black holes are in some sense quantum, that elementary particles can be interpreted as sub-Planckian black holes, and that there is a subtle connection between quantum and classical physics. |
0707.0900 | Eduard Alexis Larranaga Rubio | Alexis Larranaga | Traversable Wormholes Construction in (2+1) Gravity | 13 pages, 2 figures | Rev. Col. Fis. 40,2 (2008) 222-224 | null | null | gr-qc | null | Wormholes have been always an interesting object in gravity theories. In this
paper we make a little review of the principal properties of these objects and
the exotic matter they need to exist. Then, we obtain two specific solutions in
the formalism of (2+1)-dimensional gravity with negative cosmological constant.
The obtained geometries correspond to traversable wormholes with an exterior
geometry correspondient to the well known BTZ black hole solution. We also
discuss the distribution of exotic matter that these wormholes need.
| [
{
"created": "Fri, 6 Jul 2007 02:55:58 GMT",
"version": "v1"
},
{
"created": "Mon, 16 Jul 2007 13:28:12 GMT",
"version": "v2"
}
] | 2008-07-17 | [
[
"Larranaga",
"Alexis",
""
]
] | Wormholes have been always an interesting object in gravity theories. In this paper we make a little review of the principal properties of these objects and the exotic matter they need to exist. Then, we obtain two specific solutions in the formalism of (2+1)-dimensional gravity with negative cosmological constant. The obtained geometries correspond to traversable wormholes with an exterior geometry correspondient to the well known BTZ black hole solution. We also discuss the distribution of exotic matter that these wormholes need. |
1806.09837 | Chul-Moon Yoo | Takahisa Igata, Hideki Ishihara, Masataka Tsuchiya, Chul-Moon Yoo | Rigidly Rotating String Sticking in a Kerr Black Hole | 20 pages, 5 figures | Phys. Rev. D 98, 064021 (2018) | 10.1103/PhysRevD.98.064021 | RUP-18-16, OCU-PHYS-481, AP-GR-146 | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyze rigidly rotating Nambu--Goto strings in the Kerr spacetime,
particularly focusing on the strings sticking in the horizon. From the
regularity on the horizon, we find the condition for sticking in the horizon,
which is consistent with the second law of the black hole thermodynamics.
Energy extraction through the sticking string from a Kerr black hole occurs. We
obtain the maximum value of the luminosity of the energy extraction.
| [
{
"created": "Tue, 26 Jun 2018 08:15:45 GMT",
"version": "v1"
}
] | 2018-09-19 | [
[
"Igata",
"Takahisa",
""
],
[
"Ishihara",
"Hideki",
""
],
[
"Tsuchiya",
"Masataka",
""
],
[
"Yoo",
"Chul-Moon",
""
]
] | We analyze rigidly rotating Nambu--Goto strings in the Kerr spacetime, particularly focusing on the strings sticking in the horizon. From the regularity on the horizon, we find the condition for sticking in the horizon, which is consistent with the second law of the black hole thermodynamics. Energy extraction through the sticking string from a Kerr black hole occurs. We obtain the maximum value of the luminosity of the energy extraction. |
2205.13584 | Behnam Pourhassan | Behnam Pourhassan, Mahdi Atashi, Houcine Aounallah, Salman Sajad Wani,
Mir Faizal, Barun Majumder | Quantum Thermodynamics of a Quantum Sized AdS Black Hole | 15pages, 6 figures. Accepted for publication in NPB | Nucl.Phys.B 980 (2022) 115842 | 10.1016/j.nuclphysb.2022.115842 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | In this paper, we investigate the effects of non-perturbative quantum
gravitational corrections on a quantum sized AdS black hole. It will be
observed that these non-perturbative quantum gravitational corrections modify
the stability of this black hole. We will use the non-equilibrium quantum
thermodynamics to investigate the evaporation of this black hole between two
states. We will analyze the effects of non-perturbative quantum gravitational
corrections on this non-equilibrium quantum thermodynamics. We will explicitly
obtain the quantum work distribution for this black hole, as it evaporates
between two states. It will be observed that this quantum work distribution is
modified due to non-perturbative quantum gravitational corrections.
| [
{
"created": "Thu, 26 May 2022 19:01:17 GMT",
"version": "v1"
}
] | 2022-06-22 | [
[
"Pourhassan",
"Behnam",
""
],
[
"Atashi",
"Mahdi",
""
],
[
"Aounallah",
"Houcine",
""
],
[
"Wani",
"Salman Sajad",
""
],
[
"Faizal",
"Mir",
""
],
[
"Majumder",
"Barun",
""
]
] | In this paper, we investigate the effects of non-perturbative quantum gravitational corrections on a quantum sized AdS black hole. It will be observed that these non-perturbative quantum gravitational corrections modify the stability of this black hole. We will use the non-equilibrium quantum thermodynamics to investigate the evaporation of this black hole between two states. We will analyze the effects of non-perturbative quantum gravitational corrections on this non-equilibrium quantum thermodynamics. We will explicitly obtain the quantum work distribution for this black hole, as it evaporates between two states. It will be observed that this quantum work distribution is modified due to non-perturbative quantum gravitational corrections. |
gr-qc/9210012 | Alan R. Steif | S. Deser and Alan R. Steif | No Time Machines from Lightlike Sources in 2+1 Gravity | 13 pages | Directions in general relativity, vol 1 (Cambridge U Press 1993) | null | Brandeis preprint BRX-TH-336 | gr-qc hep-th | null | We extend the argument that spacetimes generated by two timelike particles in
D=3 gravity (or equivalently by parallel-moving cosmic strings in D=4) permit
closed timelike curves (CTC) only at the price of Misner identifications that
correspond to unphysical boundary conditions at spatial infinity and to a
tachyonic center of mass. Here we analyze geometries one or both of whose
sources are lightlike.
We make manifest both the presence of CTC at spatial infinity if they are
present at all, and the tachyonic character of the system: As the total energy
surpasses its tachyonic bound, CTC first begin to form at spatial infinity,
then spread to the interior as the energy increases further. We then show that,
in contrast, CTC are entirely forbidden in topologically massive gravity for
geometries generated by lightlike sources.
| [
{
"created": "Wed, 21 Oct 1992 16:22:07 GMT",
"version": "v1"
}
] | 2009-11-19 | [
[
"Deser",
"S.",
""
],
[
"Steif",
"Alan R.",
""
]
] | We extend the argument that spacetimes generated by two timelike particles in D=3 gravity (or equivalently by parallel-moving cosmic strings in D=4) permit closed timelike curves (CTC) only at the price of Misner identifications that correspond to unphysical boundary conditions at spatial infinity and to a tachyonic center of mass. Here we analyze geometries one or both of whose sources are lightlike. We make manifest both the presence of CTC at spatial infinity if they are present at all, and the tachyonic character of the system: As the total energy surpasses its tachyonic bound, CTC first begin to form at spatial infinity, then spread to the interior as the energy increases further. We then show that, in contrast, CTC are entirely forbidden in topologically massive gravity for geometries generated by lightlike sources. |
gr-qc/9712063 | Frank Gronwald | Frank Gronwald, Uwe Muench, Alfredo Mac\'ias, Friedrich W. Hehl | Volume elements of spacetime and a quartet of scalar fields | 7 pages RevTEX, submitted to Phys. Rev. D | Phys. Rev. D 58, 084021 (1998) | 10.1103/PhysRevD.58.084021 | null | gr-qc hep-th | null | Starting with a `bare' 4-dimensional differential manifold as a model of
spacetime, we discuss the options one has for defining a volume element which
can be used for physical theories. We show that one has to prescribe a scalar
density \sigma. Whereas conventionally \sqrt{|\det g_{ij}|} is used for that
purpose, with g_{ij} as the components of the metric, we point out other
possibilities, namely \sigma as a `dilaton' field or as a derived quantity from
either a linear connection or a quartet of scalar fields, as suggested by
Guendelman and Kaganovich.
| [
{
"created": "Mon, 15 Dec 1997 18:52:04 GMT",
"version": "v1"
}
] | 2016-08-25 | [
[
"Gronwald",
"Frank",
""
],
[
"Muench",
"Uwe",
""
],
[
"Macías",
"Alfredo",
""
],
[
"Hehl",
"Friedrich W.",
""
]
] | Starting with a `bare' 4-dimensional differential manifold as a model of spacetime, we discuss the options one has for defining a volume element which can be used for physical theories. We show that one has to prescribe a scalar density \sigma. Whereas conventionally \sqrt{|\det g_{ij}|} is used for that purpose, with g_{ij} as the components of the metric, we point out other possibilities, namely \sigma as a `dilaton' field or as a derived quantity from either a linear connection or a quartet of scalar fields, as suggested by Guendelman and Kaganovich. |
1101.1736 | Tanwi Ghosh | Tanwi Ghosh and Soumitra Sengupta | Tunneling across dilaton coupled black holes in anti de Sitter spacetime | 9 pages and 2 figures | Phys.Lett.B696:167-172,2011 | 10.1016/j.physletb.2010.12.016 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Considering generalised action for dilaton coupled Maxwell-Einstein theory in
four dimensions, Gao and Zhang obtained black holes solutions for
asymptotically anti de Sitter (Ads) and de Sitter (ds) spacetimes. We study the
Hawking radiation in Parikh-Wilczek's tunneling formalism as well as using
Bogoliubov transformations. We compare the expression of the Hawking
temperature obtained from these two different approaches. Stability and the
extremality conditions for such black holes are discussed. The exact
dependences of the Hawking temperature and flux on the dilaton coupling
parameter are determined. It is shown that the Hawking flux increases with the
dilaton coupling parameter. Finally we show that the expression for the Hawking
flux obtained using Bogoliubov transformation matches exactly with flux
calculated via chiral gauge and gravitational anomalies. This establishes a
correspondence among all these different approaches of estimating Hawking
radiation from these class of black holes.
| [
{
"created": "Mon, 10 Jan 2011 08:56:41 GMT",
"version": "v1"
}
] | 2011-02-18 | [
[
"Ghosh",
"Tanwi",
""
],
[
"Sengupta",
"Soumitra",
""
]
] | Considering generalised action for dilaton coupled Maxwell-Einstein theory in four dimensions, Gao and Zhang obtained black holes solutions for asymptotically anti de Sitter (Ads) and de Sitter (ds) spacetimes. We study the Hawking radiation in Parikh-Wilczek's tunneling formalism as well as using Bogoliubov transformations. We compare the expression of the Hawking temperature obtained from these two different approaches. Stability and the extremality conditions for such black holes are discussed. The exact dependences of the Hawking temperature and flux on the dilaton coupling parameter are determined. It is shown that the Hawking flux increases with the dilaton coupling parameter. Finally we show that the expression for the Hawking flux obtained using Bogoliubov transformation matches exactly with flux calculated via chiral gauge and gravitational anomalies. This establishes a correspondence among all these different approaches of estimating Hawking radiation from these class of black holes. |
gr-qc/0210073 | Tiberiu Harko | T.Harko, M. K. Mak | Bianchi type I universes with dilaton and magnetic fields | 10 pages, 4 figures | Int.J.Mod.Phys. D11 (2002) 1171-1182 | 10.1142/S0218271802002141 | null | gr-qc | null | We consider the dynamics of a Bianchi type I spacetime in the presence of
dilaton and magnetic fields. The general solution of the Einstein-Maxwell
dilaton field equations can be obtained in an exact parametric form. Depending
on the numerical values of the parameters of the model there are three distinct
classes of solutions. The time evolution of the mean anisotropy, shear and
deceleration parameter is considered in detail and it is shown that a
magnetic-dilaton anisotropic Bianchi type I geometry does not isotropize, the
initial anisotropy being present in the universe for all times.
| [
{
"created": "Tue, 22 Oct 2002 08:26:13 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Harko",
"T.",
""
],
[
"Mak",
"M. K.",
""
]
] | We consider the dynamics of a Bianchi type I spacetime in the presence of dilaton and magnetic fields. The general solution of the Einstein-Maxwell dilaton field equations can be obtained in an exact parametric form. Depending on the numerical values of the parameters of the model there are three distinct classes of solutions. The time evolution of the mean anisotropy, shear and deceleration parameter is considered in detail and it is shown that a magnetic-dilaton anisotropic Bianchi type I geometry does not isotropize, the initial anisotropy being present in the universe for all times. |
2207.13146 | Thanasis Karakasis | Thanasis Karakasis, George Koutsoumbas, Andri Machattou, Eleftherios
Papantonopoulos | Magnetically Charged Euler-Heisenberg Black Holes with Scalar Hair | Some typos corrected, accepted for publication in PRD | Phys. Rev. D 106, 104006 (2022) | 10.1103/PhysRevD.106.104006 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We study the Einstein-Euler-Heisenberg theory in the presence of a self
interacting scalar field, minimally coupled to gravity. We solve analytically
the field equations for the magnetically charged case and we obtain novel
magnetically charged hairy black holes. The scalar field dresses the black hole
with a secondary scalar hair. The hairy black hole develops three horizons when
Euler-Heisenberg parameter and the magnetic charge are small and the horizon
radius is getting large when the scalar charge and the gravitational mass are
large. The presence of matter and the magnetic field outside the horizon of the
black hole increases the temperature only for small black holes. Calculating
the heat capacity we show that the asymptotically AdS Euler-Heisenberg hairy
black hole undergoes a second order phase transition and then it is stabilized.
Also the weak energy condition is violated for the asymptotically AdS
Euler-Heisenberg hairy black hole.
| [
{
"created": "Tue, 26 Jul 2022 18:56:00 GMT",
"version": "v1"
},
{
"created": "Wed, 19 Oct 2022 19:26:56 GMT",
"version": "v2"
},
{
"created": "Fri, 28 Oct 2022 07:05:15 GMT",
"version": "v3"
}
] | 2022-11-15 | [
[
"Karakasis",
"Thanasis",
""
],
[
"Koutsoumbas",
"George",
""
],
[
"Machattou",
"Andri",
""
],
[
"Papantonopoulos",
"Eleftherios",
""
]
] | We study the Einstein-Euler-Heisenberg theory in the presence of a self interacting scalar field, minimally coupled to gravity. We solve analytically the field equations for the magnetically charged case and we obtain novel magnetically charged hairy black holes. The scalar field dresses the black hole with a secondary scalar hair. The hairy black hole develops three horizons when Euler-Heisenberg parameter and the magnetic charge are small and the horizon radius is getting large when the scalar charge and the gravitational mass are large. The presence of matter and the magnetic field outside the horizon of the black hole increases the temperature only for small black holes. Calculating the heat capacity we show that the asymptotically AdS Euler-Heisenberg hairy black hole undergoes a second order phase transition and then it is stabilized. Also the weak energy condition is violated for the asymptotically AdS Euler-Heisenberg hairy black hole. |
2003.13935 | Andrea Giusti | Valerio Faraoni, Andrea Giusti, Jeremy C\^ot\'e | Turnaround radius in scalar-tensor gravity with quasilocal mass | 10 pages, no figures, to appear in Phys.Rev.D | Phys. Rev. D 102, 044002 (2020) | 10.1103/PhysRevD.102.044002 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Following an existing procedure in general relativity, the turnaround radius
of a spherical structure is studied in scalar-tensor gravity using a new
prescription for the analog of the Hawking-Hayward quasilocal mass in this
class of theories.
| [
{
"created": "Tue, 31 Mar 2020 03:19:33 GMT",
"version": "v1"
},
{
"created": "Sat, 25 Jul 2020 06:24:57 GMT",
"version": "v2"
}
] | 2020-08-12 | [
[
"Faraoni",
"Valerio",
""
],
[
"Giusti",
"Andrea",
""
],
[
"Côté",
"Jeremy",
""
]
] | Following an existing procedure in general relativity, the turnaround radius of a spherical structure is studied in scalar-tensor gravity using a new prescription for the analog of the Hawking-Hayward quasilocal mass in this class of theories. |
2111.06987 | David Reitze | Peter Couvares, Ian Bird, Ed Porter, Stefano Bagnasco, Michele
Punturo, David Reitze, Stavros Katsanevas, Takaaki Kajita, Vicky Kalogera,
Harald Lueck, David McClelland, Sheila Rowan, Gary Sanders, B.S.
Sathyaprakash, David Shoemaker, Jo van den Brand | Gravitational Wave Data Analysis: Computing Challenges in the 3G Era | 26 pages, no figures | null | null | null | gr-qc astro-ph.HE astro-ph.IM | http://creativecommons.org/licenses/by/4.0/ | Cyber infrastructure will be a critical consideration in the development of
next generation gravitational-wave detectors. The demand for data analysis
computing in the 3G era will be driven by the high number of detections as well
as the expanded search parameter space for compact astrophysical objects and
the subsequent parameter estimation follow-up required to extract the nature of
the sources. Additionally, there will be an increased need to develop
appropriate and scalable computing cyberinfrastructure, including data access
and transfer protocols, and storage and management of software tools, that have
sustainable development, support, and management processes. This report
identifies the major challenges and opportunities facing 3G gravitational-wave
observatories and presents recommendations for addressing them.
This report is the fourth in a six part series of reports by the GWIC 3G
Subcommittee: i) Expanding the Reach of Gravitational Wave Observatories to the
Edge of the Universe, ii) The Next Generation Global Gravitational Wave
Observatory: The Science Book, iii) 3G R&D: R&D for the Next Generation of
Ground-based Gravitational Wave Detectors, iv) Gravitational Wave Data
Analysis: Computing Challenges in the 3G Era (this report), v) Future
Ground-based Gravitational-wave Observatories: Synergies with Other Scientific
Communities, and vi) An Exploration of Possible Governance Models for the
Future Global Gravitational-Wave Observatory Network.
| [
{
"created": "Fri, 12 Nov 2021 23:46:07 GMT",
"version": "v1"
}
] | 2021-11-16 | [
[
"Couvares",
"Peter",
""
],
[
"Bird",
"Ian",
""
],
[
"Porter",
"Ed",
""
],
[
"Bagnasco",
"Stefano",
""
],
[
"Punturo",
"Michele",
""
],
[
"Reitze",
"David",
""
],
[
"Katsanevas",
"Stavros",
""
],
[
"Kajita",
"Takaaki",
""
],
[
"Kalogera",
"Vicky",
""
],
[
"Lueck",
"Harald",
""
],
[
"McClelland",
"David",
""
],
[
"Rowan",
"Sheila",
""
],
[
"Sanders",
"Gary",
""
],
[
"Sathyaprakash",
"B. S.",
""
],
[
"Shoemaker",
"David",
""
],
[
"Brand",
"Jo van den",
""
]
] | Cyber infrastructure will be a critical consideration in the development of next generation gravitational-wave detectors. The demand for data analysis computing in the 3G era will be driven by the high number of detections as well as the expanded search parameter space for compact astrophysical objects and the subsequent parameter estimation follow-up required to extract the nature of the sources. Additionally, there will be an increased need to develop appropriate and scalable computing cyberinfrastructure, including data access and transfer protocols, and storage and management of software tools, that have sustainable development, support, and management processes. This report identifies the major challenges and opportunities facing 3G gravitational-wave observatories and presents recommendations for addressing them. This report is the fourth in a six part series of reports by the GWIC 3G Subcommittee: i) Expanding the Reach of Gravitational Wave Observatories to the Edge of the Universe, ii) The Next Generation Global Gravitational Wave Observatory: The Science Book, iii) 3G R&D: R&D for the Next Generation of Ground-based Gravitational Wave Detectors, iv) Gravitational Wave Data Analysis: Computing Challenges in the 3G Era (this report), v) Future Ground-based Gravitational-wave Observatories: Synergies with Other Scientific Communities, and vi) An Exploration of Possible Governance Models for the Future Global Gravitational-Wave Observatory Network. |
1804.04007 | Subhajit Saha | Anindita Mondal and Subhajit Saha | A closer look at the Barboza-Alcaniz equation of state parametrization | 6 pages, 3 figures | Romanian Journal of Physics 63, 106 (2018) | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Barboza-Alcaniz EoS parametrization has been considered and its
$q$-parametrization has been investigated in search for a thermodynamic
motivation. For this, we have studied the validity of the generalized second
law of thermodynamics as well as the thermodynamic equilibrium considering the
cosmological apparent horizon as the boundary. Also, an expression for the
particle creation rate has been obtained in terms of $q$ assuming an adiabatic
particle creation scenario and its behavior has been studied for consistency
during various phases of evolution of the Universe as suggested by various
thermodynamic arguments found in the literature.
| [
{
"created": "Mon, 9 Apr 2018 19:01:39 GMT",
"version": "v1"
}
] | 2018-04-12 | [
[
"Mondal",
"Anindita",
""
],
[
"Saha",
"Subhajit",
""
]
] | The Barboza-Alcaniz EoS parametrization has been considered and its $q$-parametrization has been investigated in search for a thermodynamic motivation. For this, we have studied the validity of the generalized second law of thermodynamics as well as the thermodynamic equilibrium considering the cosmological apparent horizon as the boundary. Also, an expression for the particle creation rate has been obtained in terms of $q$ assuming an adiabatic particle creation scenario and its behavior has been studied for consistency during various phases of evolution of the Universe as suggested by various thermodynamic arguments found in the literature. |
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