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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1310.2185 | Raissa Mendes | Raissa F. P. Mendes, George E. A. Matsas, and Daniel A. T. Vanzella | Quantum versus classical instability of scalar fields in curved
backgrounds | 5 pages, 1 figure; condensed and revised version matching published
one | Phys. Rev. D 89, 047503 (2014) | 10.1103/PhysRevD.89.047503 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | General-relativistic stable spacetimes can be made unstable under the
presence of certain nonminimally coupled free scalar fields. In this paper, we
analyze the evolution of linear scalar-field perturbations in spherically
symmetric spacetimes and compare the classical stability analysis with a
recently discussed quantum field one. In particular, it is shown that vacuum
fluctuations lead to natural seeds for the unstable phase, whereas in the
classical framework the presence of such seeds in the initial conditions must
be assumed.
| [
{
"created": "Tue, 8 Oct 2013 15:53:37 GMT",
"version": "v1"
},
{
"created": "Mon, 10 Mar 2014 14:34:20 GMT",
"version": "v2"
}
] | 2014-03-11 | [
[
"Mendes",
"Raissa F. P.",
""
],
[
"Matsas",
"George E. A.",
""
],
[
"Vanzella",
"Daniel A. T.",
""
]
] | General-relativistic stable spacetimes can be made unstable under the presence of certain nonminimally coupled free scalar fields. In this paper, we analyze the evolution of linear scalar-field perturbations in spherically symmetric spacetimes and compare the classical stability analysis with a recently discussed quantum field one. In particular, it is shown that vacuum fluctuations lead to natural seeds for the unstable phase, whereas in the classical framework the presence of such seeds in the initial conditions must be assumed. |
2202.03426 | Hristu Culetu | Hristu Culetu | A Vaidya-type spacetime with no singularities | 13 pages, no figures, version accepted for publication in Int. J.
Mod. Phys. D, https://doi.org/10.1142/S0218271822501243 | null | 10.1142/S0218271822501243 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A regular Vaidya-type line-element is proposed in this work. The mass
function depends both on the temporal and the spatial coordinates. The
curvature invariants and the source stress tensor $T^{a}_{~b}$ are finite in
the whole space. The energy conditions for $T^{a}_{~b}$ are satisfied if
$k^{2}<2vr$, where $k$ is a positive constant and $v,r$ are coordinates. It is
found that the radial pressure has a maximum very close to $r = 2m~ (r>2m), v =
2m$. The energy crossing a sphere of constant radius is akin to
Lundgren-Schmekel-York quasilocal energy. The Newtonian acceleration of the
timelike geodesics has an extra term (compared to the result of Piesnack and
Kassner) which leads to rejecting effects.
| [
{
"created": "Sat, 5 Feb 2022 23:11:16 GMT",
"version": "v1"
},
{
"created": "Fri, 14 Oct 2022 19:38:19 GMT",
"version": "v2"
}
] | 2023-01-25 | [
[
"Culetu",
"Hristu",
""
]
] | A regular Vaidya-type line-element is proposed in this work. The mass function depends both on the temporal and the spatial coordinates. The curvature invariants and the source stress tensor $T^{a}_{~b}$ are finite in the whole space. The energy conditions for $T^{a}_{~b}$ are satisfied if $k^{2}<2vr$, where $k$ is a positive constant and $v,r$ are coordinates. It is found that the radial pressure has a maximum very close to $r = 2m~ (r>2m), v = 2m$. The energy crossing a sphere of constant radius is akin to Lundgren-Schmekel-York quasilocal energy. The Newtonian acceleration of the timelike geodesics has an extra term (compared to the result of Piesnack and Kassner) which leads to rejecting effects. |
1206.0923 | Santanu Das | Santanu Das | Mach's principle and the origin of the quantum phenomenon | 13 pages | null | null | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Concept of inertial mass is not well defined in physics. For defining
inertial mass of a particle we need to know its acceleration under some force
in an inertial reference frame, which itself is defined by the motion of its
background objects. Therefore, the inertial mass of a particle is not
completely its intrinsic property and depends on the position of the particle
itself and and all other particles (which we refer as background) in the
universe. But the background of a particle keeps on fluctuating randomly due to
different physical phenomenon in the universe. Therefore, the exact position or
the mass of a particle can not be determined at any time, without having full
information about all the other particles in the universe. Hence, in this
paper, we define the dynamics of a particle statistically. We show that the
fluctuations in the background of an object contributes to an extra energy term
in the total energy of the particle. If we treat this extra energy term as the
quantum potential then it leads to the Schrodinger equation. Some examples are
also given to show how a classical interpretation can be given to some quantum
mechanical phenomenon.
| [
{
"created": "Mon, 4 Jun 2012 16:57:45 GMT",
"version": "v1"
},
{
"created": "Mon, 16 Feb 2015 11:11:08 GMT",
"version": "v2"
}
] | 2015-02-17 | [
[
"Das",
"Santanu",
""
]
] | Concept of inertial mass is not well defined in physics. For defining inertial mass of a particle we need to know its acceleration under some force in an inertial reference frame, which itself is defined by the motion of its background objects. Therefore, the inertial mass of a particle is not completely its intrinsic property and depends on the position of the particle itself and and all other particles (which we refer as background) in the universe. But the background of a particle keeps on fluctuating randomly due to different physical phenomenon in the universe. Therefore, the exact position or the mass of a particle can not be determined at any time, without having full information about all the other particles in the universe. Hence, in this paper, we define the dynamics of a particle statistically. We show that the fluctuations in the background of an object contributes to an extra energy term in the total energy of the particle. If we treat this extra energy term as the quantum potential then it leads to the Schrodinger equation. Some examples are also given to show how a classical interpretation can be given to some quantum mechanical phenomenon. |
1808.03418 | Hideyoshi Arakida | Hideyoshi Arakida | General Relativistic Aberration Equation and Measurable Angle of Light
Ray in Kerr Spacetime | 17 pages, 4 figures | International Journal of Modern Physics DVol. 30, No. 06, 2150045
(2021) | 10.1142/S0218271821500450 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We will mainly discuss the measurable angle (local angle) of the light ray
$\psi_P$ at the position of the observer $P$ instead of the total deflection
angle (global angle) $\alpha$ in Kerr spacetime. We will investigate not only
the effect of the gravito-magnetic field or frame dragging but also the
contribution of the motion of the observer with a coordinate radial velocity
$v^r$ and a coordinate transverse velocity $bv^{\phi}$ ($b$ is the impact
parameter and $v^{\phi}$ is a coordinate angular velocity) which are converted
from the components of the 4-velocity of the observer $u^r$ and $u^{\phi}$,
respectively. Because the motion of observer causes an aberration, we will
employ the general relativistic aberration equation to obtain the measurable
angle $\psi$. The measurable angle $\psi$ given in this paper can be applied
not only to the case of the observer located in an asymptotically flat region
but also to the case of the observer placed within the curved and
finite-distance region. Moreover, when the observer is in radial motion, the
total deflection angle $\alpha_{\rm radial}$ can be expressed by $\alpha_{\rm
radial} = (1 + v^r)\alpha_{\rm static}$ which is consistent with the overall
scaling factor $1 - v$ with respect to the total deflection angle $\alpha{\rm
static}$ in the static case. instead of $1 - 2v$ where $v$ is the velocity of
the lens object. On the other hand, when the observer is in transverse motion,
the total deflection angle is given by the form $\alpha_{\rm transverse} = (1 +
bv^{\phi}/2)\alpha_{\rm static}$ if we define the transverse velocity as having
the form $bv^{\phi}$.
| [
{
"created": "Fri, 10 Aug 2018 05:51:05 GMT",
"version": "v1"
},
{
"created": "Mon, 13 Aug 2018 00:25:34 GMT",
"version": "v2"
},
{
"created": "Wed, 11 Mar 2020 02:17:04 GMT",
"version": "v3"
},
{
"created": "Fri, 22 Jan 2021 05:26:51 GMT",
"version": "v4"
}
] | 2021-05-06 | [
[
"Arakida",
"Hideyoshi",
""
]
] | We will mainly discuss the measurable angle (local angle) of the light ray $\psi_P$ at the position of the observer $P$ instead of the total deflection angle (global angle) $\alpha$ in Kerr spacetime. We will investigate not only the effect of the gravito-magnetic field or frame dragging but also the contribution of the motion of the observer with a coordinate radial velocity $v^r$ and a coordinate transverse velocity $bv^{\phi}$ ($b$ is the impact parameter and $v^{\phi}$ is a coordinate angular velocity) which are converted from the components of the 4-velocity of the observer $u^r$ and $u^{\phi}$, respectively. Because the motion of observer causes an aberration, we will employ the general relativistic aberration equation to obtain the measurable angle $\psi$. The measurable angle $\psi$ given in this paper can be applied not only to the case of the observer located in an asymptotically flat region but also to the case of the observer placed within the curved and finite-distance region. Moreover, when the observer is in radial motion, the total deflection angle $\alpha_{\rm radial}$ can be expressed by $\alpha_{\rm radial} = (1 + v^r)\alpha_{\rm static}$ which is consistent with the overall scaling factor $1 - v$ with respect to the total deflection angle $\alpha{\rm static}$ in the static case. instead of $1 - 2v$ where $v$ is the velocity of the lens object. On the other hand, when the observer is in transverse motion, the total deflection angle is given by the form $\alpha_{\rm transverse} = (1 + bv^{\phi}/2)\alpha_{\rm static}$ if we define the transverse velocity as having the form $bv^{\phi}$. |
1304.1702 | Andrea Vicer\'e | Flavio Vetrano, Andrea Vicer\'e | Newtonian noise limit in atom interferometers for gravitational wave
detection | 14 pages, 4 figures | The European Physical Journal C 73 (2013) 2590 | 10.1140/epjc/s10052-013-2590-8 | null | gr-qc physics.ins-det | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we study the influence of the newtonian noise on atom
interferometers applied to the detection of gravitational waves, and we compute
the resulting limits to the sensitivity in two different configurations: a
single atom interferometer, or a pair of atom interferometers operated in a
differential configuration. We find that for the instrumental configurations
considered, and operating in the frequency range [0.1-10] Hz, the limits would
be comparable to those affecting large scale optical interferometers.
| [
{
"created": "Fri, 5 Apr 2013 13:12:19 GMT",
"version": "v1"
},
{
"created": "Mon, 10 Jun 2013 16:36:20 GMT",
"version": "v2"
},
{
"created": "Tue, 15 Oct 2013 20:38:12 GMT",
"version": "v3"
}
] | 2013-10-17 | [
[
"Vetrano",
"Flavio",
""
],
[
"Viceré",
"Andrea",
""
]
] | In this work we study the influence of the newtonian noise on atom interferometers applied to the detection of gravitational waves, and we compute the resulting limits to the sensitivity in two different configurations: a single atom interferometer, or a pair of atom interferometers operated in a differential configuration. We find that for the instrumental configurations considered, and operating in the frequency range [0.1-10] Hz, the limits would be comparable to those affecting large scale optical interferometers. |
1811.01707 | Farook Rahaman | Faizuddin Ahmed, Farook Rahaman and Susmita Sarkar | Black holes/naked singularities in four-dimensional non-static
space-time and the energy-momentum distributions | 18 pages, 6 figures. Accepted in EPJA. arXiv admin note: text overlap
with arXiv:gr-qc/0309002 by other authors | null | 10.1140/epja/i2018-12650-y | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this article, we discuss four dimensional non-static space-times in the
background of de-Sitter and anti-de Sitter spaces with the matter-energy
sources a stiff fluid, anisotropic fluid, and an electromagnetic field. Under
various parameter conditions the solutions may represent models of naked
singularity and/or black holes. Finally, the energy-momentum distributions
using the complexes of Landau-Lifshitz, Einstein, Papapetrou, and M{\o}ller
prescriptions, were evaluated.
| [
{
"created": "Thu, 1 Nov 2018 18:16:41 GMT",
"version": "v1"
}
] | 2019-01-30 | [
[
"Ahmed",
"Faizuddin",
""
],
[
"Rahaman",
"Farook",
""
],
[
"Sarkar",
"Susmita",
""
]
] | In this article, we discuss four dimensional non-static space-times in the background of de-Sitter and anti-de Sitter spaces with the matter-energy sources a stiff fluid, anisotropic fluid, and an electromagnetic field. Under various parameter conditions the solutions may represent models of naked singularity and/or black holes. Finally, the energy-momentum distributions using the complexes of Landau-Lifshitz, Einstein, Papapetrou, and M{\o}ller prescriptions, were evaluated. |
2408.03016 | Dong-han Yeom | Xiao Yan Chew, Il Gyeong Choi, Hyuk Jung Kim, Dong-han Yeom | Can a naked singularity be formed during the gravitational collapse of a
Janis-Newman-Winicour solution? | 13 pages, 6 figures | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | The Janis-Newman-Winicour (JNW) spacetime possesses a naked singularity,
although it represents an exact particle-like solution to the
Einstein-Klein-Gordon theory with a massless scalar field. Here, we investigate
the possible formation of a naked singularity in the JNW spacetime, using the
thin-shell approximation to describe the gravitational collapse. By introducing
different matter contents to construct thin-shells, we demonstrate the
impossibility of naked singularity formation during the gravitational collapse
unless the causality or null energy condition of the thin-shell is violated.
Therefore, the weak cosmic censorship is satisfied even with the naked
singularity of the JNW spacetime.
| [
{
"created": "Tue, 6 Aug 2024 07:56:28 GMT",
"version": "v1"
}
] | 2024-08-07 | [
[
"Chew",
"Xiao Yan",
""
],
[
"Choi",
"Il Gyeong",
""
],
[
"Kim",
"Hyuk Jung",
""
],
[
"Yeom",
"Dong-han",
""
]
] | The Janis-Newman-Winicour (JNW) spacetime possesses a naked singularity, although it represents an exact particle-like solution to the Einstein-Klein-Gordon theory with a massless scalar field. Here, we investigate the possible formation of a naked singularity in the JNW spacetime, using the thin-shell approximation to describe the gravitational collapse. By introducing different matter contents to construct thin-shells, we demonstrate the impossibility of naked singularity formation during the gravitational collapse unless the causality or null energy condition of the thin-shell is violated. Therefore, the weak cosmic censorship is satisfied even with the naked singularity of the JNW spacetime. |
1108.4385 | Ujjal Debnath | Surajit Chattopadhyay, Ujjal Debnath and Samarpita Bhattacharya | Study of Thermodynamic Quantities in Generalized Gravity Theories | 15 pages, 12 figures | null | 10.1007/s10773-012-1198-3 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we have studied the thermodynamic quantities like temperature
of the universe, heat capacity and squared speed of sound in generalized
gravity theories like Brans-Dicke, Ho$\check{\text r}$ava-Lifshitz and $f(R)$
gravities. We have considered the universe filled with dark matter and dark
energy. Also we have considered the equation of state parameters for open,
closed and flat models. We have observed that in all cases the equation of
state behaves like quintessence. The temperature and heat capacity of the
universe are found to decrease with the expansion of the universe in all cases.
In Brans-Dicke and $f(R)$ gravity theories the squared speed of sound is found
to exhibit increasing behavior for open, closed and flat models and in
Ho$\check{\text r}$ava-Lifshitz gravity theory it is found to exhibit
decreasing behavior for open and closed models with the evolution of the
universe. However, for flat universe, the squared speed of sound remains
constant in Ho$\check{\text r}$ava-Lifshitz gravity.
| [
{
"created": "Mon, 22 Aug 2011 17:40:47 GMT",
"version": "v1"
}
] | 2015-05-30 | [
[
"Chattopadhyay",
"Surajit",
""
],
[
"Debnath",
"Ujjal",
""
],
[
"Bhattacharya",
"Samarpita",
""
]
] | In this work, we have studied the thermodynamic quantities like temperature of the universe, heat capacity and squared speed of sound in generalized gravity theories like Brans-Dicke, Ho$\check{\text r}$ava-Lifshitz and $f(R)$ gravities. We have considered the universe filled with dark matter and dark energy. Also we have considered the equation of state parameters for open, closed and flat models. We have observed that in all cases the equation of state behaves like quintessence. The temperature and heat capacity of the universe are found to decrease with the expansion of the universe in all cases. In Brans-Dicke and $f(R)$ gravity theories the squared speed of sound is found to exhibit increasing behavior for open, closed and flat models and in Ho$\check{\text r}$ava-Lifshitz gravity theory it is found to exhibit decreasing behavior for open and closed models with the evolution of the universe. However, for flat universe, the squared speed of sound remains constant in Ho$\check{\text r}$ava-Lifshitz gravity. |
1306.1176 | Jorge Paramos | Orfeu Bertolami, Riccardo March, Jorge P\'aramos | Solar System constraints to nonminimally coupled gravity | 13 pages, 3 figures | null | 10.1103/PhysRevD.88.064019 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We extend the analysis of Chiba, Smith and Erickcek \cite{CSE} of Solar
System constraints on $f(R)$ gravity to a class of nonminimally coupled (NMC)
theories of gravity. These generalize $f(R)$ theories by replacing the action
functional of General Relativity (GR) with a more general form involving two
functions $f^1(R)$ and $f^2(R)$ of the Ricci scalar curvature $R$. While the
function $f^1(R)$ is a nonlinear term in the action, analogous to $f(R)$
gravity, the function $f^2(R)$ yields a NMC between the matter Lagrangian
density $\LL_m$ and the scalar curvature. The developed method allows for
obtaining constraints on the admissible classes of functions $f^1(R)$ and
$f^2(R)$, by requiring that predictions of NMC gravity are compatible with
Solar System tests of gravity. We apply this method to a NMC model which
accounts for the observed accelerated expansion of the Universe.
| [
{
"created": "Wed, 5 Jun 2013 17:10:51 GMT",
"version": "v1"
}
] | 2015-06-16 | [
[
"Bertolami",
"Orfeu",
""
],
[
"March",
"Riccardo",
""
],
[
"Páramos",
"Jorge",
""
]
] | We extend the analysis of Chiba, Smith and Erickcek \cite{CSE} of Solar System constraints on $f(R)$ gravity to a class of nonminimally coupled (NMC) theories of gravity. These generalize $f(R)$ theories by replacing the action functional of General Relativity (GR) with a more general form involving two functions $f^1(R)$ and $f^2(R)$ of the Ricci scalar curvature $R$. While the function $f^1(R)$ is a nonlinear term in the action, analogous to $f(R)$ gravity, the function $f^2(R)$ yields a NMC between the matter Lagrangian density $\LL_m$ and the scalar curvature. The developed method allows for obtaining constraints on the admissible classes of functions $f^1(R)$ and $f^2(R)$, by requiring that predictions of NMC gravity are compatible with Solar System tests of gravity. We apply this method to a NMC model which accounts for the observed accelerated expansion of the Universe. |
1111.1252 | Christopher Duston | Christopher L. Duston | Topspin Networks in Loop Quantum Gravity | 33 pages, significantly updated and improved | Classical and Quantum Gravity 29 (2012) 205015 | 10.1088/0264-9381/29/20/205015 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discuss the extension of loop quantum gravity to topspin networks, a
proposal which allows topological information to be encoded in spin networks.
We will show that this requires minimal changes to the phase space, C*-algebra
and Hilbert space of cylindrical functions. We will also discuss the area and
Hamiltonian operators, and show how they depend on the topology. This extends
the idea of "background independence" in loop quantum gravity to include
topology as well as geometry. It is hoped this work will confirm the usefulness
of the topspin network formalism and open up several new avenues for research
into quantum gravity.
| [
{
"created": "Fri, 4 Nov 2011 21:13:09 GMT",
"version": "v1"
},
{
"created": "Tue, 24 Apr 2012 21:15:22 GMT",
"version": "v2"
}
] | 2015-06-03 | [
[
"Duston",
"Christopher L.",
""
]
] | We discuss the extension of loop quantum gravity to topspin networks, a proposal which allows topological information to be encoded in spin networks. We will show that this requires minimal changes to the phase space, C*-algebra and Hilbert space of cylindrical functions. We will also discuss the area and Hamiltonian operators, and show how they depend on the topology. This extends the idea of "background independence" in loop quantum gravity to include topology as well as geometry. It is hoped this work will confirm the usefulness of the topspin network formalism and open up several new avenues for research into quantum gravity. |
1209.0635 | Agnes Fienga | A. Fienga | Planetary ephemerides and gravity tests in the solar system | Proceedings of the Rencontres de Moriond 2011 | null | null | null | gr-qc astro-ph.EP physics.space-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We review here the tests of fundamental physics based on the dynamics of
solar system objects.
| [
{
"created": "Tue, 4 Sep 2012 13:04:53 GMT",
"version": "v1"
}
] | 2012-09-05 | [
[
"Fienga",
"A.",
""
]
] | We review here the tests of fundamental physics based on the dynamics of solar system objects. |
1710.05606 | Katsuki Aoki | Katsuki Aoki, Kei-ichi Maeda, Yosuke Misonoh, and Hirotada Okawa | Massive Graviton Geons | 16 pages, 7 tables, 3 figures; v2: references added, improved
discussion, published version | Phys. Rev. D 97, 044005 (2018) | 10.1103/PhysRevD.97.044005 | WU-AP/1705/17 | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We find vacuum solutions such that massive gravitons are confined in a local
spacetime region by their gravitational energy in asymptotically flat
spacetimes in the context of the bigravity theory. We call such
self-gravitating objects massive graviton geons. The basic equations can be
reduced to the Schr\"odinger-Poisson equations with the tensor "wavefunction"
in the Newtonian limit. We obtain a non-spherically symmetric solution with
$j=2,\ell=0$ as well as a spherically symmetric solution with $j=0,\ell=2$ in
this system where $j$ is the total angular momentum quantum number and $\ell$
is the orbital angular momentum quantum number, respectively. The energy
eigenvalue of the Schr\"odinger equation in the non-spherical solution is
smaller than that in the spherical solution. We then study the perturbative
stability of the spherical solution and find that there is an unstable mode in
the quadrupole mode perturbations which may be interpreted as the transition
mode to the non-spherical solution. The results suggest that the
non-spherically symmetric solution is the ground state of the massive graviton
geon. The massive graviton geons may decay in time due to emissions of
gravitational waves but this timescale can be quite long when the massive
gravitons are non-relativistic and then the geons can be long-lived. We also
argue possible prospects of the massive graviton geons: applications to the
ultralight dark matter scenario, nonlinear (in)stability of the Minkowski
spacetime, and a quantum transition of the spacetime.
| [
{
"created": "Mon, 16 Oct 2017 10:26:00 GMT",
"version": "v1"
},
{
"created": "Thu, 8 Feb 2018 06:06:04 GMT",
"version": "v2"
}
] | 2018-02-14 | [
[
"Aoki",
"Katsuki",
""
],
[
"Maeda",
"Kei-ichi",
""
],
[
"Misonoh",
"Yosuke",
""
],
[
"Okawa",
"Hirotada",
""
]
] | We find vacuum solutions such that massive gravitons are confined in a local spacetime region by their gravitational energy in asymptotically flat spacetimes in the context of the bigravity theory. We call such self-gravitating objects massive graviton geons. The basic equations can be reduced to the Schr\"odinger-Poisson equations with the tensor "wavefunction" in the Newtonian limit. We obtain a non-spherically symmetric solution with $j=2,\ell=0$ as well as a spherically symmetric solution with $j=0,\ell=2$ in this system where $j$ is the total angular momentum quantum number and $\ell$ is the orbital angular momentum quantum number, respectively. The energy eigenvalue of the Schr\"odinger equation in the non-spherical solution is smaller than that in the spherical solution. We then study the perturbative stability of the spherical solution and find that there is an unstable mode in the quadrupole mode perturbations which may be interpreted as the transition mode to the non-spherical solution. The results suggest that the non-spherically symmetric solution is the ground state of the massive graviton geon. The massive graviton geons may decay in time due to emissions of gravitational waves but this timescale can be quite long when the massive gravitons are non-relativistic and then the geons can be long-lived. We also argue possible prospects of the massive graviton geons: applications to the ultralight dark matter scenario, nonlinear (in)stability of the Minkowski spacetime, and a quantum transition of the spacetime. |
gr-qc/9907051 | Victor Mikhailovich Zhuravlev | S. V. Chervon, V. M. Zhuravlev | The cosmological model with an analytic exit from inflation | 27 pages LaTex, 7 figures PS | null | null | ULSU/LFR-9901 | gr-qc | null | A cosmological model of homogeneous and isotropic spatially flat Universe
with gravitating self-interacting scalar field is considered. The exact
solution, admitting an analytical exit from inflationary stage into a radiation
era and a matter dominated epoch, is obtained by virtue of ``fine turning of
the potential'' method. We found that an inflationary stage is supported by
decay of higgs bosons in the framework of the solution obtained. Freidmann's
regim is associated with adiabatical expantion of the Universe, filled by the
matter with special equation of state. Thus we presented the exact solution
which solve the problem of transition from an inflationary to a radiation eras
or long standing `exit' problem.
| [
{
"created": "Wed, 14 Jul 1999 11:27:23 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Chervon",
"S. V.",
""
],
[
"Zhuravlev",
"V. M.",
""
]
] | A cosmological model of homogeneous and isotropic spatially flat Universe with gravitating self-interacting scalar field is considered. The exact solution, admitting an analytical exit from inflationary stage into a radiation era and a matter dominated epoch, is obtained by virtue of ``fine turning of the potential'' method. We found that an inflationary stage is supported by decay of higgs bosons in the framework of the solution obtained. Freidmann's regim is associated with adiabatical expantion of the Universe, filled by the matter with special equation of state. Thus we presented the exact solution which solve the problem of transition from an inflationary to a radiation eras or long standing `exit' problem. |
1602.04461 | Pierre Fleury | Pierre Fleury, Fabien Nugier, Giuseppe Fanizza | Geodesic-light-cone coordinates and the Bianchi I spacetime | 27 pages, 5 figures, v2 matches published version | JCAP 06 (2016) 008 | 10.1088/1475-7516/2016/06/008 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The geodesic-light-cone (GLC) coordinates are a useful tool to analyse light
propagation and observations in cosmological models. In this article, we
propose a detailed, pedagogical, and rigorous introduction to this coordinate
system, explore its gauge degrees of freedom, and emphasize its interest when
geometric optics is at stake. We then apply the GLC formalism to the
homogeneous and anisotropic Bianchi I cosmology. More than a simple
illustration, this application (i) allows us to show that the Weinberg
conjecture according to which gravitational lensing does not affect the proper
area of constant-redshift surfaces is significantly violated in a globally
anisotropic universe; and (ii) offers a glimpse into new ways to constrain
cosmic isotropy from the Hubble diagram.
| [
{
"created": "Sun, 14 Feb 2016 14:23:44 GMT",
"version": "v1"
},
{
"created": "Wed, 8 Jun 2016 13:04:27 GMT",
"version": "v2"
}
] | 2016-06-09 | [
[
"Fleury",
"Pierre",
""
],
[
"Nugier",
"Fabien",
""
],
[
"Fanizza",
"Giuseppe",
""
]
] | The geodesic-light-cone (GLC) coordinates are a useful tool to analyse light propagation and observations in cosmological models. In this article, we propose a detailed, pedagogical, and rigorous introduction to this coordinate system, explore its gauge degrees of freedom, and emphasize its interest when geometric optics is at stake. We then apply the GLC formalism to the homogeneous and anisotropic Bianchi I cosmology. More than a simple illustration, this application (i) allows us to show that the Weinberg conjecture according to which gravitational lensing does not affect the proper area of constant-redshift surfaces is significantly violated in a globally anisotropic universe; and (ii) offers a glimpse into new ways to constrain cosmic isotropy from the Hubble diagram. |
1112.3351 | Paolo Pani | Nicolas Yunes, Paolo Pani, Vitor Cardoso | Gravitational Waves from Quasicircular Extreme Mass-Ratio Inspirals as
Probes of Scalar-Tensor Theories | 28 pages, 9 figures, 2 tables. Matches PRD version. Abstract abridged | Phys.Rev. D85 (2012) 102003 | 10.1103/PhysRevD.85.102003 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A stellar-mass compact object spiraling into a supermassive black hole, an
extreme-mass-ratio inspiral (EMRI), is one of the targets of future
gravitational-wave detectors and it offers a unique opportunity to test General
Relativity (GR) in the strong-field. We study whether generic scalar-tensor
(ST) theories can be further constrained with EMRIs. We show that in the EMRI
limit, all such theories universally reduce to massive or massless Brans-Dicke
theory and that black holes do not emit dipolar radiation to all orders in
post-Newtonian (PN) theory. For massless theories, we calculate the scalar
energy flux in the Teukolsky formalism to all orders in PN theory and fit it to
a high-order PN expansion. We derive the PN ST corrections to the Fourier
transform of the gravitational wave response and map it to the parameterized
post-Einsteinian framework. We use the effective-one-body framework adapted to
EMRIs to calculate the ST modifications to the gravitational waveform. We find
that such corrections are smaller than those induced in the early inspiral of
comparable-mass binaries, leading to projected bounds on the coupling that are
worse than current Solar System ones. Brans-Dicke theory modifies the
weak-field, with deviations in the energy flux that are largest at small
velocities. For massive theories, superradiance can lead to resonances in the
scalar energy flux that can lead to floating orbits outside the innermost
stable circular orbit and that last until the supermassive black hole loses
enough mass and spin-angular momentum. If such floating orbits occur in the
frequency band of LISA, they would lead to a large dephasing (~1e6 rads),
preventing detection with GR templates. A detection that is consistent with GR
would then rule out floating resonances at frequencies lower than the lowest
observed frequency, allowing for the strongest constraints yet on massive ST
theories.
| [
{
"created": "Wed, 14 Dec 2011 21:00:17 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Aug 2012 10:02:46 GMT",
"version": "v2"
}
] | 2012-08-07 | [
[
"Yunes",
"Nicolas",
""
],
[
"Pani",
"Paolo",
""
],
[
"Cardoso",
"Vitor",
""
]
] | A stellar-mass compact object spiraling into a supermassive black hole, an extreme-mass-ratio inspiral (EMRI), is one of the targets of future gravitational-wave detectors and it offers a unique opportunity to test General Relativity (GR) in the strong-field. We study whether generic scalar-tensor (ST) theories can be further constrained with EMRIs. We show that in the EMRI limit, all such theories universally reduce to massive or massless Brans-Dicke theory and that black holes do not emit dipolar radiation to all orders in post-Newtonian (PN) theory. For massless theories, we calculate the scalar energy flux in the Teukolsky formalism to all orders in PN theory and fit it to a high-order PN expansion. We derive the PN ST corrections to the Fourier transform of the gravitational wave response and map it to the parameterized post-Einsteinian framework. We use the effective-one-body framework adapted to EMRIs to calculate the ST modifications to the gravitational waveform. We find that such corrections are smaller than those induced in the early inspiral of comparable-mass binaries, leading to projected bounds on the coupling that are worse than current Solar System ones. Brans-Dicke theory modifies the weak-field, with deviations in the energy flux that are largest at small velocities. For massive theories, superradiance can lead to resonances in the scalar energy flux that can lead to floating orbits outside the innermost stable circular orbit and that last until the supermassive black hole loses enough mass and spin-angular momentum. If such floating orbits occur in the frequency band of LISA, they would lead to a large dephasing (~1e6 rads), preventing detection with GR templates. A detection that is consistent with GR would then rule out floating resonances at frequencies lower than the lowest observed frequency, allowing for the strongest constraints yet on massive ST theories. |
1803.11358 | Ali \"Ovg\"un Dr. | Giovanni Otalora, Ali \"Ovg\"un, Joel Saavedra, and Nelson Videla | Inflation from a nonlinear magnetic monopole field nonminimally coupled
to curvature | 15 pages, 4 figures. Accepted for publication in Journal of Cosmology
and Astroparticle Physics (JCAP) | JCAP06(2018)003 | 10.1088/1475-7516/2018/06/003 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the context of nonminimally coupled $f(R)$ gravity theories, we study
early inflation driven by a nonlinear monopole magnetic field which is
nonminimally coupled to curvature. In order to isolate the effects of the
nonminimal coupling between matter and curvature we assume the pure
gravitational sector to have the Einstein-Hilbert form. Thus, we study the most
simple model with a nonminimal coupling function which is linear in the Ricci
scalar. From an effective fluid description, we show the existence of an early
exponential expansion regime of the Universe, followed by a transition to a
radiation-dominated era. In particular, by applying the most recent results of
the Planck collaboration we set the limits on the parameter of the nonminimal
coupling, and the quotient of the nonminimal coupling and the nonlinear
monopole magnetic scales. We found that these parameters must take large values
in order to satisfy the observational constraints. Furthermore, by obtaining
the relation for the graviton mass, we show the consistency of our results with
the recent gravitational wave data GW$170817$ of LIGO and Virgo.
| [
{
"created": "Fri, 30 Mar 2018 06:33:40 GMT",
"version": "v1"
},
{
"created": "Mon, 28 May 2018 02:11:05 GMT",
"version": "v2"
}
] | 2018-06-05 | [
[
"Otalora",
"Giovanni",
""
],
[
"Övgün",
"Ali",
""
],
[
"Saavedra",
"Joel",
""
],
[
"Videla",
"Nelson",
""
]
] | In the context of nonminimally coupled $f(R)$ gravity theories, we study early inflation driven by a nonlinear monopole magnetic field which is nonminimally coupled to curvature. In order to isolate the effects of the nonminimal coupling between matter and curvature we assume the pure gravitational sector to have the Einstein-Hilbert form. Thus, we study the most simple model with a nonminimal coupling function which is linear in the Ricci scalar. From an effective fluid description, we show the existence of an early exponential expansion regime of the Universe, followed by a transition to a radiation-dominated era. In particular, by applying the most recent results of the Planck collaboration we set the limits on the parameter of the nonminimal coupling, and the quotient of the nonminimal coupling and the nonlinear monopole magnetic scales. We found that these parameters must take large values in order to satisfy the observational constraints. Furthermore, by obtaining the relation for the graviton mass, we show the consistency of our results with the recent gravitational wave data GW$170817$ of LIGO and Virgo. |
1508.02281 | Farook Rahaman | Farook Rahaman, Sunil D. Maharaj, Iftikar Hossain Sardar, Koushik
Chakraborty | Conformally symmetric relativistic star | Accepted for publication in Mod.Phys.Lett.A | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate whether compact stars having Tolman-like interior geometry
admit conformal symmetry. Taking anisotropic pressure along the two principal
directions within the compact object, we obtain physically relevant quantities
such as transverse and radial pressure, density and redshift function. We study
the equation of state for the matter distribution inside the star. From the
relation between pressure and density function of the constituent matter, we
explore the nature and properties of the interior matter. The red shift
function, compactness parameter are found to be physically reasonable. The
matter inside the star satisfies the null, weak and strong energy conditions.
Finally, we compare the masses and radii predicted from the model with
corresponding values in some observed stars.
| [
{
"created": "Mon, 3 Aug 2015 09:12:14 GMT",
"version": "v1"
},
{
"created": "Fri, 22 Jul 2016 04:35:49 GMT",
"version": "v2"
}
] | 2016-07-25 | [
[
"Rahaman",
"Farook",
""
],
[
"Maharaj",
"Sunil D.",
""
],
[
"Sardar",
"Iftikar Hossain",
""
],
[
"Chakraborty",
"Koushik",
""
]
] | We investigate whether compact stars having Tolman-like interior geometry admit conformal symmetry. Taking anisotropic pressure along the two principal directions within the compact object, we obtain physically relevant quantities such as transverse and radial pressure, density and redshift function. We study the equation of state for the matter distribution inside the star. From the relation between pressure and density function of the constituent matter, we explore the nature and properties of the interior matter. The red shift function, compactness parameter are found to be physically reasonable. The matter inside the star satisfies the null, weak and strong energy conditions. Finally, we compare the masses and radii predicted from the model with corresponding values in some observed stars. |
2102.00373 | Ying Wang | Ying Wang, Wei Sun, Fuyao Liu, and Xin Wu | Construction of Explicit Symplectic Integrators in General Relativity.
I. Schwarzschild Black Holes | 10 pages,2 figures | The Astrophysical Journal, 907:66 (10pp), 2021 February | 10.3847/1538-4357/abcb8d | null | gr-qc astro-ph.IM nlin.CD physics.comp-ph | http://creativecommons.org/licenses/by/4.0/ | Symplectic integrators that preserve the geometric structure of Hamiltonian
flows and do not exhibit secular growth in energy errors are suitable for the
long-term integration of N-body Hamiltonian systems in the solar system.
However, the construction of explicit symplectic integrators is frequently
difficult in general relativity because all variables are inseparable.
Moreover, even if two analytically integrable splitting parts exist in a
relativistic Hamiltonian, all analytical solutions are not explicit functions
of proper time. Naturally, implicit symplectic integrators, such as the
midpoint rule, are applicable to this case. In general, these integrators are
numerically more expensive to solve than same-order explicit symplectic
algorithms. To address this issue, we split the Hamiltonian of Schwarzschild
spacetime geometry into four integrable parts with analytical solutions as
explicit functions of proper time. In this manner, second- and fourth-order
explicit symplectic integrators can be easily made available. The new
algorithms are also useful for modeling the chaotic motion of charged particles
around a black hole with an external magnetic field. They demonstrate excellent
long-term performance in maintaining bounded Hamiltonian errors and saving
computational cost when appropriate proper time steps are adopted.
| [
{
"created": "Sun, 31 Jan 2021 04:04:57 GMT",
"version": "v1"
}
] | 2021-02-02 | [
[
"Wang",
"Ying",
""
],
[
"Sun",
"Wei",
""
],
[
"Liu",
"Fuyao",
""
],
[
"Wu",
"Xin",
""
]
] | Symplectic integrators that preserve the geometric structure of Hamiltonian flows and do not exhibit secular growth in energy errors are suitable for the long-term integration of N-body Hamiltonian systems in the solar system. However, the construction of explicit symplectic integrators is frequently difficult in general relativity because all variables are inseparable. Moreover, even if two analytically integrable splitting parts exist in a relativistic Hamiltonian, all analytical solutions are not explicit functions of proper time. Naturally, implicit symplectic integrators, such as the midpoint rule, are applicable to this case. In general, these integrators are numerically more expensive to solve than same-order explicit symplectic algorithms. To address this issue, we split the Hamiltonian of Schwarzschild spacetime geometry into four integrable parts with analytical solutions as explicit functions of proper time. In this manner, second- and fourth-order explicit symplectic integrators can be easily made available. The new algorithms are also useful for modeling the chaotic motion of charged particles around a black hole with an external magnetic field. They demonstrate excellent long-term performance in maintaining bounded Hamiltonian errors and saving computational cost when appropriate proper time steps are adopted. |
2101.10915 | David Keitel | David Keitel, Rodrigo Tenorio, Gregory Ashton, Reinhard Prix | PyFstat: a Python package for continuous gravitational-wave data
analysis | 4 pages, updated to match published version. Software repository:
https://github.com/PyFstat/PyFstat/ | Journal of Open Source Software, 6(60), 3000 (2021) | 10.21105/joss.03000 | LIGO-P2100008 | gr-qc astro-ph.IM | http://creativecommons.org/licenses/by/4.0/ | Gravitational waves in the sensitivity band of ground-based detectors can be
emitted by a number of astrophysical sources, including not only binary
coalescences, but also individual spinning neutron stars. The most promising
signals from such sources, although not yet detected, are long-lasting,
quasi-monochromatic Continuous Waves (CWs). The PyFstat package provides tools
to perform a range of CW data-analysis tasks. It revolves around the
F-statistic, a matched-filter detection statistic for CW signals that has been
one of the standard methods for LIGO-Virgo CW searches for two decades. PyFstat
is built on top of established routines in LALSuite but through its more modern
Python interface it enables a flexible approach to designing new search
strategies. Hence, it serves a dual function of (i) making LALSuite CW
functionality more easily accessible through a Python interface, thus
facilitating the new user experience and, for developers, the exploratory
implementation of novel methods; and (ii) providing a set of production-ready
search classes for use cases not yet covered by LALSuite itself, most notably
for MCMC-based followup of promising candidates from wide-parameter-space
searches.
| [
{
"created": "Tue, 26 Jan 2021 16:35:35 GMT",
"version": "v1"
},
{
"created": "Tue, 6 Apr 2021 21:08:01 GMT",
"version": "v2"
}
] | 2021-04-08 | [
[
"Keitel",
"David",
""
],
[
"Tenorio",
"Rodrigo",
""
],
[
"Ashton",
"Gregory",
""
],
[
"Prix",
"Reinhard",
""
]
] | Gravitational waves in the sensitivity band of ground-based detectors can be emitted by a number of astrophysical sources, including not only binary coalescences, but also individual spinning neutron stars. The most promising signals from such sources, although not yet detected, are long-lasting, quasi-monochromatic Continuous Waves (CWs). The PyFstat package provides tools to perform a range of CW data-analysis tasks. It revolves around the F-statistic, a matched-filter detection statistic for CW signals that has been one of the standard methods for LIGO-Virgo CW searches for two decades. PyFstat is built on top of established routines in LALSuite but through its more modern Python interface it enables a flexible approach to designing new search strategies. Hence, it serves a dual function of (i) making LALSuite CW functionality more easily accessible through a Python interface, thus facilitating the new user experience and, for developers, the exploratory implementation of novel methods; and (ii) providing a set of production-ready search classes for use cases not yet covered by LALSuite itself, most notably for MCMC-based followup of promising candidates from wide-parameter-space searches. |
1205.3184 | Vitor Cardoso | Vitor Cardoso, Paolo Pani | Tidal acceleration of black holes and superradiance | 12 pages, 4 figures. v2: minor changes. Final version to appear in
CQG | null | 10.1088/0264-9381/30/4/045011 | null | gr-qc astro-ph.HE hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Tidal effects have long ago locked the Moon in synchronous rotation with the
Earth and progressively increase the Earth-Moon distance. This "tidal
acceleration" hinges on dissipation. Binaries containing black holes may also
be tidally accelerated, dissipation being caused by the event horizon - a
flexible, viscous one-way membrane. In fact, this process is known for many
years under a different guise: superradiance. In General Relativity, tidal
acceleration is obscured by gravitational-wave emission. However, when coupling
to light scalar degrees of freedom is allowed, an induced dipole moment
produces a "polarization acceleration", which might be orders of magnitude
stronger than tidal quadrupolar effects. Consequences for optical and
gravitational-wave observations are intriguing and it is not impossible that
imprints of such mechanism have already been observed.
| [
{
"created": "Mon, 14 May 2012 20:12:08 GMT",
"version": "v1"
},
{
"created": "Thu, 17 Jan 2013 22:26:03 GMT",
"version": "v2"
}
] | 2015-06-05 | [
[
"Cardoso",
"Vitor",
""
],
[
"Pani",
"Paolo",
""
]
] | Tidal effects have long ago locked the Moon in synchronous rotation with the Earth and progressively increase the Earth-Moon distance. This "tidal acceleration" hinges on dissipation. Binaries containing black holes may also be tidally accelerated, dissipation being caused by the event horizon - a flexible, viscous one-way membrane. In fact, this process is known for many years under a different guise: superradiance. In General Relativity, tidal acceleration is obscured by gravitational-wave emission. However, when coupling to light scalar degrees of freedom is allowed, an induced dipole moment produces a "polarization acceleration", which might be orders of magnitude stronger than tidal quadrupolar effects. Consequences for optical and gravitational-wave observations are intriguing and it is not impossible that imprints of such mechanism have already been observed. |
gr-qc/0011009 | Rod Aros | Rodrigo Aros | Analysing Charges in even dimensions | null | Class. Quantum Grav. 18 (2001) 5359 | 10.1088/0264-9381/18/24/303 | null | gr-qc | null | Lanczos-Lovelock theories of gravity, in its first order version, are studied
on asymptotically locally anti de Sitter spaces. It is shown that
thermodynamics satisfies the standard behavior and an expression for entropy is
found for this formalism. Finally a short analysis of the algebra of conserved
charges is displayed.
| [
{
"created": "Fri, 3 Nov 2000 13:57:06 GMT",
"version": "v1"
},
{
"created": "Fri, 2 Feb 2001 14:25:50 GMT",
"version": "v2"
},
{
"created": "Wed, 15 Mar 2006 18:12:31 GMT",
"version": "v3"
}
] | 2009-10-31 | [
[
"Aros",
"Rodrigo",
""
]
] | Lanczos-Lovelock theories of gravity, in its first order version, are studied on asymptotically locally anti de Sitter spaces. It is shown that thermodynamics satisfies the standard behavior and an expression for entropy is found for this formalism. Finally a short analysis of the algebra of conserved charges is displayed. |
1003.0878 | Giulia Gubitosi | Giulia Gubitosi, Giuseppe Genovese, Giovanni Amelino-Camelia,
Alessandro Melchiorri | Planck-scale modifications to Electrodynamics characterized by a
space-like symmetry-breaking vector | null | Phys.Rev.D82:024013,2010 | 10.1103/PhysRevD.82.024013 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the study of Planck-scale ("quantum-gravity induced") violations of
Lorentz symmetry, an important role was played by the deformed-electrodynamics
model introduced by Myers and Pospelov. Its reliance on conventional effective
quantum field theory, and its description of symmetry-violation effects simply
in terms of a four-vector with nonzero component only in the time-direction,
rendered it an ideal target for experimentalists and a natural concept-testing
ground for many theorists. At this point however the experimental limits on the
single Myers-Pospelov parameter, after improving steadily over these past few
years, are "super-Planckian", {\it i.e.} they take the model out of actual
interest from a conventional quantum-gravity perspective. In light of this we
here argue that it may be appropriate to move on to the next level of
complexity, still with vectorial symmetry violation but adopting a generic
four-vector. We also offer a preliminary characterization of the phenomenology
of this more general framework, sufficient to expose a rather significant
increase in complexity with respect to the original Myers-Pospelov setup. Most
of these novel features are linked to the presence of spatial anisotropy, which
is particularly pronounced when the symmetry-breaking vector is space-like, and
they are such that they reduce the bound-setting power of certain types of
observations in astrophysics.
| [
{
"created": "Wed, 3 Mar 2010 20:10:04 GMT",
"version": "v1"
}
] | 2014-11-20 | [
[
"Gubitosi",
"Giulia",
""
],
[
"Genovese",
"Giuseppe",
""
],
[
"Amelino-Camelia",
"Giovanni",
""
],
[
"Melchiorri",
"Alessandro",
""
]
] | In the study of Planck-scale ("quantum-gravity induced") violations of Lorentz symmetry, an important role was played by the deformed-electrodynamics model introduced by Myers and Pospelov. Its reliance on conventional effective quantum field theory, and its description of symmetry-violation effects simply in terms of a four-vector with nonzero component only in the time-direction, rendered it an ideal target for experimentalists and a natural concept-testing ground for many theorists. At this point however the experimental limits on the single Myers-Pospelov parameter, after improving steadily over these past few years, are "super-Planckian", {\it i.e.} they take the model out of actual interest from a conventional quantum-gravity perspective. In light of this we here argue that it may be appropriate to move on to the next level of complexity, still with vectorial symmetry violation but adopting a generic four-vector. We also offer a preliminary characterization of the phenomenology of this more general framework, sufficient to expose a rather significant increase in complexity with respect to the original Myers-Pospelov setup. Most of these novel features are linked to the presence of spatial anisotropy, which is particularly pronounced when the symmetry-breaking vector is space-like, and they are such that they reduce the bound-setting power of certain types of observations in astrophysics. |
2204.10742 | Maximiliano Isi | Maximiliano Isi, Will M. Farr, Katerina Chatziioannou | Comparing Bayes factors and hierarchical inference for testing general
relativity with gravitational waves | null | null | 10.1103/PhysRevD.106.024048 | LIGO-P2200099 | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | In the context of testing general relativity with gravitational waves,
constraints obtained with multiple events are typically combined either through
a hierarchical formalism or though a combined multiplicative Bayes factor. We
show that the well-known dependence of Bayes factors on the analysis priors in
regions of the parameter space without likelihood support can lead to strong
confidence in favor of incorrect conclusions when one employs the
multiplicative Bayes factor. Bayes factors $\mathcal{O}(1)$ are ambivalent as
they depend sensitively on the analysis priors, which are rarely set in a
principled way; additionally, combined Bayes factors $>\mathcal{O}(10^3)$ can
be obtained in favor of the incorrect conclusion depending on the analysis
priors when many $\mathcal{O}(1)$ Bayes factors are multiplied, and
specifically when the priors are much wider than the underlying population. The
hierarchical analysis that instead infers the ensemble distribution of the
individual beyond-general-relativity constraints does not suffer from this
problem, and generically converges to favor the correct conclusion. Rather than
a naive multiplication, a more reliable Bayes factor can be computed from the
hierarchical analysis. We present a number of toy models showing that the
practice of multiplying Bayes Factors can lead to incorrect conclusions.
| [
{
"created": "Fri, 22 Apr 2022 15:04:18 GMT",
"version": "v1"
}
] | 2022-08-17 | [
[
"Isi",
"Maximiliano",
""
],
[
"Farr",
"Will M.",
""
],
[
"Chatziioannou",
"Katerina",
""
]
] | In the context of testing general relativity with gravitational waves, constraints obtained with multiple events are typically combined either through a hierarchical formalism or though a combined multiplicative Bayes factor. We show that the well-known dependence of Bayes factors on the analysis priors in regions of the parameter space without likelihood support can lead to strong confidence in favor of incorrect conclusions when one employs the multiplicative Bayes factor. Bayes factors $\mathcal{O}(1)$ are ambivalent as they depend sensitively on the analysis priors, which are rarely set in a principled way; additionally, combined Bayes factors $>\mathcal{O}(10^3)$ can be obtained in favor of the incorrect conclusion depending on the analysis priors when many $\mathcal{O}(1)$ Bayes factors are multiplied, and specifically when the priors are much wider than the underlying population. The hierarchical analysis that instead infers the ensemble distribution of the individual beyond-general-relativity constraints does not suffer from this problem, and generically converges to favor the correct conclusion. Rather than a naive multiplication, a more reliable Bayes factor can be computed from the hierarchical analysis. We present a number of toy models showing that the practice of multiplying Bayes Factors can lead to incorrect conclusions. |
2212.00472 | Rahul Thakur | Sukanta Panda, Arun Rana and Rahul Thakur | Constant-Roll Inflation in modified $f(R,\phi)$ gravity model using
Palatini Formalism | 13 Pages and 10 Figures | null | 10.1140/epjc/s10052-023-11459-1 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work, we study a constant-roll inflationary model in the Palatini
formalism using modified gravity. Here our action consists a non-minimal
coupling of a scalar field $\phi$ with Ricci scalar $R$ in a general form of
$f(R,\phi)$. Using Palatini approach, we write its equivalent scalar-tensor
form in the Einstein frame and then apply the constant-roll condition in the
equation of motion for the inflaton field. Later the tensor-to-scalar ratio and
the spectral index are calculated using the slow-roll parameters and the
results obtained are matched with the Planck 2018 data. We found that the
results agree nicely with the observations within the parameter regime under
consideration.
| [
{
"created": "Thu, 1 Dec 2022 12:55:25 GMT",
"version": "v1"
}
] | 2023-04-19 | [
[
"Panda",
"Sukanta",
""
],
[
"Rana",
"Arun",
""
],
[
"Thakur",
"Rahul",
""
]
] | In this work, we study a constant-roll inflationary model in the Palatini formalism using modified gravity. Here our action consists a non-minimal coupling of a scalar field $\phi$ with Ricci scalar $R$ in a general form of $f(R,\phi)$. Using Palatini approach, we write its equivalent scalar-tensor form in the Einstein frame and then apply the constant-roll condition in the equation of motion for the inflaton field. Later the tensor-to-scalar ratio and the spectral index are calculated using the slow-roll parameters and the results obtained are matched with the Planck 2018 data. We found that the results agree nicely with the observations within the parameter regime under consideration. |
1110.4833 | Jonathan Ziprick | Laurent Freidel, Marc Geiller, Jonathan Ziprick | Continuous formulation of the Loop Quantum Gravity phase space | published version | Class. Quantum Grav. 30 (2013) 085013 (28pp) | null | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we study the discrete classical phase space of loop gravity,
which is expressed in terms of the holonomy-flux variables, and show how it is
related to the continuous phase space of general relativity. In particular, we
prove an isomorphism between the loop gravity discrete phase space and the
symplectic reduction of the continuous phase space with respect to a flatness
constraint. This gives for the first time a precise relationship between the
continuum and holonomy-flux variables. Our construction shows that the fluxes
depend on the three-geometry, but also explicitly on the connection, explaining
their non commutativity. It also clearly shows that the flux variables do not
label a unique geometry, but rather a class of gauge-equivalent geometries.
This allows us to resolve the tension between the loop gravity geometrical
interpretation in terms of singular geometry, and the spin foam interpretation
in terms of piecewise flat geometry, since we establish that both geometries
belong to the same equivalence class. This finally gives us a clear
understanding of the relationship between the piecewise flat spin foam
geometries and Regge geometries, which are only piecewise-linear flat: While
Regge geometry corresponds to metrics whose curvature is concentrated around
straight edges, the loop gravity geometry correspond to metrics whose curvature
is concentrated around not necessarily straight edges.
| [
{
"created": "Fri, 21 Oct 2011 16:24:15 GMT",
"version": "v1"
},
{
"created": "Mon, 28 Jan 2013 02:56:53 GMT",
"version": "v2"
},
{
"created": "Wed, 3 Apr 2013 15:41:00 GMT",
"version": "v3"
}
] | 2013-04-04 | [
[
"Freidel",
"Laurent",
""
],
[
"Geiller",
"Marc",
""
],
[
"Ziprick",
"Jonathan",
""
]
] | In this paper, we study the discrete classical phase space of loop gravity, which is expressed in terms of the holonomy-flux variables, and show how it is related to the continuous phase space of general relativity. In particular, we prove an isomorphism between the loop gravity discrete phase space and the symplectic reduction of the continuous phase space with respect to a flatness constraint. This gives for the first time a precise relationship between the continuum and holonomy-flux variables. Our construction shows that the fluxes depend on the three-geometry, but also explicitly on the connection, explaining their non commutativity. It also clearly shows that the flux variables do not label a unique geometry, but rather a class of gauge-equivalent geometries. This allows us to resolve the tension between the loop gravity geometrical interpretation in terms of singular geometry, and the spin foam interpretation in terms of piecewise flat geometry, since we establish that both geometries belong to the same equivalence class. This finally gives us a clear understanding of the relationship between the piecewise flat spin foam geometries and Regge geometries, which are only piecewise-linear flat: While Regge geometry corresponds to metrics whose curvature is concentrated around straight edges, the loop gravity geometry correspond to metrics whose curvature is concentrated around not necessarily straight edges. |
1906.05386 | Carlos A. R. Herdeiro | C. Herdeiro, I. Perapechka, E. Radu, Ya. Shnir | Asymptotically flat spinning scalar, Dirac and Proca stars | 12 pages, 3 figures | null | 10.1016/j.physletb.2019.134845 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Einstein's gravity minimally coupled to free, massive, classical fundamental
fields admits particle-like solutions. These are asymptotically flat,
everywhere non-singular configurations that realise Wheeler's concept of a
geon: a localised lump of self-gravitating energy whose existence is anchored
on the non-linearities of general relativity, trivialising in the flat
spacetime limit. In arXiv:1708.05674 the key properties for the existence of
these solutions (also referred to as stars or self-gravitating solitons) were
discussed - which include a harmonic time dependence in the matter field -, and
a comparative analysis of the stars arising in the Einstein-Klein-Gordon,
Einstein-Dirac and Einstein-Proca models was performed, for the particular case
of static, spherically symmetric spacetimes. In the present work we generalise
this analysis for spinning solutions. In particular, the spinning
Einstein-Dirac stars are reported here for the first time. Our analysis shows
that the high degree of universality observed in the spherical case remains
when angular momentum is allowed. Thus, as classical field theory solutions,
these self-gravitating solitons are rather insensitive to the fundamental
fermionic or bosonic nature of the corresponding field, displaying similar
features. We describe some physical properties and, in particular, we observe
that the angular momentum of the spinning stars satisfies the quantisation
condition $J=m N,$ for all models, where $N$ is the particle number and $m$ is
an integer for the bosonic fields and a half-integer for the Dirac field. The
way in which this quantisation condition arises, however, is more subtle for
the non-zero spin fields.
| [
{
"created": "Wed, 12 Jun 2019 21:31:47 GMT",
"version": "v1"
}
] | 2019-08-14 | [
[
"Herdeiro",
"C.",
""
],
[
"Perapechka",
"I.",
""
],
[
"Radu",
"E.",
""
],
[
"Shnir",
"Ya.",
""
]
] | Einstein's gravity minimally coupled to free, massive, classical fundamental fields admits particle-like solutions. These are asymptotically flat, everywhere non-singular configurations that realise Wheeler's concept of a geon: a localised lump of self-gravitating energy whose existence is anchored on the non-linearities of general relativity, trivialising in the flat spacetime limit. In arXiv:1708.05674 the key properties for the existence of these solutions (also referred to as stars or self-gravitating solitons) were discussed - which include a harmonic time dependence in the matter field -, and a comparative analysis of the stars arising in the Einstein-Klein-Gordon, Einstein-Dirac and Einstein-Proca models was performed, for the particular case of static, spherically symmetric spacetimes. In the present work we generalise this analysis for spinning solutions. In particular, the spinning Einstein-Dirac stars are reported here for the first time. Our analysis shows that the high degree of universality observed in the spherical case remains when angular momentum is allowed. Thus, as classical field theory solutions, these self-gravitating solitons are rather insensitive to the fundamental fermionic or bosonic nature of the corresponding field, displaying similar features. We describe some physical properties and, in particular, we observe that the angular momentum of the spinning stars satisfies the quantisation condition $J=m N,$ for all models, where $N$ is the particle number and $m$ is an integer for the bosonic fields and a half-integer for the Dirac field. The way in which this quantisation condition arises, however, is more subtle for the non-zero spin fields. |
2312.16123 | Alesandro Santos | F. Ahmed, J. C. R. de Souza and A. F. Santos | Cosmological constant Petrov type-N space-time in Ricci-inverse gravity | 15 pages, accepted for publication in AOP | null | 10.1016/j.aop.2023.169578 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Our focus is on a specific type-N space-time that exhibits closed time-like
curves in general relativity theory within the framework of Ricci-inverse
gravity model. The matter-energy content is solely composed of a pure radiation
field, and it adheres to the energy conditions while featuring a negative
cosmological constant. One of the key findings in this investigation is the
non-zero determinant of the Ricci tensor ($R_{\mu\nu}$), which implies the
existence of an anti-curvature tensor ($A^{\mu\nu}$) and, as a consequence, an
anti-curvature scalar ($A \neq R^{-1}$). Furthermore, we establish that this
type-N space-time serves as a solution within modified gravity theories via the
Ricci-inverse model, which involves adjustments to the cosmological constant
($\Lambda$) and the energy density ($\rho$) of the radiation field expressed in
terms of a coupling constant. As a result, our findings suggest that causality
violations remain possible within the framework of this Ricci-inverse gravity
model, alongside the predictions of general relativity.
| [
{
"created": "Tue, 26 Dec 2023 17:14:57 GMT",
"version": "v1"
}
] | 2023-12-27 | [
[
"Ahmed",
"F.",
""
],
[
"de Souza",
"J. C. R.",
""
],
[
"Santos",
"A. F.",
""
]
] | Our focus is on a specific type-N space-time that exhibits closed time-like curves in general relativity theory within the framework of Ricci-inverse gravity model. The matter-energy content is solely composed of a pure radiation field, and it adheres to the energy conditions while featuring a negative cosmological constant. One of the key findings in this investigation is the non-zero determinant of the Ricci tensor ($R_{\mu\nu}$), which implies the existence of an anti-curvature tensor ($A^{\mu\nu}$) and, as a consequence, an anti-curvature scalar ($A \neq R^{-1}$). Furthermore, we establish that this type-N space-time serves as a solution within modified gravity theories via the Ricci-inverse model, which involves adjustments to the cosmological constant ($\Lambda$) and the energy density ($\rho$) of the radiation field expressed in terms of a coupling constant. As a result, our findings suggest that causality violations remain possible within the framework of this Ricci-inverse gravity model, alongside the predictions of general relativity. |
1701.08176 | Josep Llosa | Josep Llosa | An extension of Poincar\'e group based on generalized Fermi-Walker
coordinates | arXiv admin note: text overlap with arXiv:1512.07465 | Class. Quantum Grav. 34 (2017) 205003(21pp) | 10.1088/1361-6382/aa8972 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The class of accelerated and rotating reference frames has been studied on
the basis of generalized Fermi-Walker coordinates. We obtain the infinitesimal
transformations connecting any two of these frames and also their commutation
relations. We thus have an infinite dimensional extension of the Poincar\'e
algebra and, although it turns out to be Abelian extension, and hence trivial,
it is noteworthy that, contrarily to Lorentz boosts, acceleration and
rotational boost generators commute with each other and with the generators of
Poincar\'e group as well.
| [
{
"created": "Fri, 27 Jan 2017 19:18:14 GMT",
"version": "v1"
}
] | 2017-11-21 | [
[
"Llosa",
"Josep",
""
]
] | The class of accelerated and rotating reference frames has been studied on the basis of generalized Fermi-Walker coordinates. We obtain the infinitesimal transformations connecting any two of these frames and also their commutation relations. We thus have an infinite dimensional extension of the Poincar\'e algebra and, although it turns out to be Abelian extension, and hence trivial, it is noteworthy that, contrarily to Lorentz boosts, acceleration and rotational boost generators commute with each other and with the generators of Poincar\'e group as well. |
2004.14985 | Thomas Sotiriou | Georgios Antoniou, Lorenzo Bordin, Thomas P. Sotiriou | Compact object scalarization with general relativity as a cosmic
attractor | 5 pages, 3 figures; v2: corrected typo in legend of Fig. 1 | Phys. Rev. D 103, 024012 (2021) | 10.1103/PhysRevD.103.024012 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We demonstrate that there are theories that exhibit spontaneous scalarization
in the strong gravity regime while having General Relativity with a constant
scalar as a cosmological attractor. We identify the minimal model that has this
property and discuss its extensions.
| [
{
"created": "Thu, 30 Apr 2020 17:31:41 GMT",
"version": "v1"
},
{
"created": "Sun, 3 May 2020 16:50:56 GMT",
"version": "v2"
}
] | 2022-03-14 | [
[
"Antoniou",
"Georgios",
""
],
[
"Bordin",
"Lorenzo",
""
],
[
"Sotiriou",
"Thomas P.",
""
]
] | We demonstrate that there are theories that exhibit spontaneous scalarization in the strong gravity regime while having General Relativity with a constant scalar as a cosmological attractor. We identify the minimal model that has this property and discuss its extensions. |
1304.5906 | Stoytcho Yazadjiev | Stoytcho S. Yazadjiev | Thermodynamics of rotating charged dilaton black holes in an external
magnetic field | 11 pages. arXiv admin note: text overlap with arXiv:1302.5530;v2
typos corrected | null | 10.1016/j.physletb.2013.05.028 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the present paper we study the long-standing problem for the
thermodynamics of magnetized dilaton black holes. For this purpose we construct
an exact solution describing a rotating charged dilaton black hole immersed in
an external magnetic field and discuss its basic properties. We derive a
Smarr-like relation and the thermodynamics first law for these magnetized black
holes. The novelty in the thermodynamics of the magnetized black holes is the
appearance of new terms proportional to the magnetic momentum of the black
holes in the Smarr-like relation and the first law.
| [
{
"created": "Mon, 22 Apr 2013 10:23:27 GMT",
"version": "v1"
},
{
"created": "Mon, 9 Sep 2013 09:45:10 GMT",
"version": "v2"
}
] | 2015-06-15 | [
[
"Yazadjiev",
"Stoytcho S.",
""
]
] | In the present paper we study the long-standing problem for the thermodynamics of magnetized dilaton black holes. For this purpose we construct an exact solution describing a rotating charged dilaton black hole immersed in an external magnetic field and discuss its basic properties. We derive a Smarr-like relation and the thermodynamics first law for these magnetized black holes. The novelty in the thermodynamics of the magnetized black holes is the appearance of new terms proportional to the magnetic momentum of the black holes in the Smarr-like relation and the first law. |
2302.06157 | Pantelis Apostolopoulos | Pantelis S. Apostolopoulos | A class of 5D inhomogeneous models with a cosmological constant | 5 pages, accepted version prepared for the "2nd Electronic Conference
on Universe" (16 Feb-2 Mar 2023) | Phys. Sci. Forum 2023, 7, 33 | 10.3390/ECU2023-14064 | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | In this work we would like to address the problem of the effect of bulk
matter on the brane cosmological evolution in a general way. We assume that the
spatial part of the brane metric is not maximally symmetric, therefore
spatially inhomogeneous. However we retain the conformal flatness property of
the standard cosmological model (FRW) i.e. the Weyl tensor of the induced 4D
geometry is zero. We refer to it as Spatially Inhomogeneous Irrotational (SII)
brane. It is shown that the model can be regarded as the 5D generalization of
the SII spacetimes found recently [1].
| [
{
"created": "Mon, 13 Feb 2023 07:36:44 GMT",
"version": "v1"
}
] | 2023-03-17 | [
[
"Apostolopoulos",
"Pantelis S.",
""
]
] | In this work we would like to address the problem of the effect of bulk matter on the brane cosmological evolution in a general way. We assume that the spatial part of the brane metric is not maximally symmetric, therefore spatially inhomogeneous. However we retain the conformal flatness property of the standard cosmological model (FRW) i.e. the Weyl tensor of the induced 4D geometry is zero. We refer to it as Spatially Inhomogeneous Irrotational (SII) brane. It is shown that the model can be regarded as the 5D generalization of the SII spacetimes found recently [1]. |
1606.04944 | Shahar Hod | Shahar Hod | The entropy emission properties of near-extremal Reissner-Nordstr\"om
black holes | 5 pages | Physical Review D 93, 104027 (2016) | 10.1103/PhysRevD.93.104027 | null | gr-qc astro-ph.HE hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Bekenstein and Mayo have revealed an interesting property of evaporating
$(3+1)$-dimensional Schwarzschild black holes: their entropy emission rates
$\dot S_{\text{Sch}}$ are related to their energy emission rates $P$ by the
simple relation $\dot S_{\text{Sch}}=C_{\text{Sch}}\times (P/\hbar)^{1/2}$.
Remembering that $(1+1)$-dimensional perfect black-body emitters are
characterized by the same functional relation, $\dot
S^{1+1}=C^{1+1}\times(P/\hbar)^{1/2}$, Bekenstein and Mayo have concluded that,
in their entropy emission properties, $(3+1)$-dimensional Schwarzschild black
holes behave effectively as $(1+1)$-dimensional entropy emitters. One naturally
wonders whether all black holes behave as simple $(1+1)$-dimensional entropy
emitters? In order to address this interesting question, we shall study in this
paper the entropy emission properties of Reissner-Nordstr\"om black holes. We
shall show, in particular, that the physical properties which characterize the
neutral sector of the Hawking emission spectra of these black holes can be
studied {\it analytically} in the near-extremal $T_{\text{BH}}\to0$ regime. We
find that the Hawking radiation spectra of massless neutral scalar fields and
coupled electromagnetic-gravitational fields are characterized by the
non-trivial entropy-energy relations $\dot S^{\text{Scalar}}_{\text{RN}} =
-C^{\text{Scalar}}_{\text{RN}} \times (AP^3/\hbar^3)^{1/4} \ln(AP/\hbar)$ and
$\dot S^{\text{Elec-Grav}}_{\text{RN}} = -C^{\text{Elec-Grav}}_{\text{RN}}
\times (A^4P^9/\hbar^9)^{1/10} \ln(AP/\hbar)$ in the near-extremal
$T_{\text{BH}}\to0$ limit (here $A$ is the surface area of the
Reissner-Nordstr\"om black hole). Our analytical results therefore indicate
that {\it not} all black holes behave as simple $(1+1)$-dimensional entropy
emitters.
| [
{
"created": "Wed, 15 Jun 2016 20:00:03 GMT",
"version": "v1"
}
] | 2016-06-22 | [
[
"Hod",
"Shahar",
""
]
] | Bekenstein and Mayo have revealed an interesting property of evaporating $(3+1)$-dimensional Schwarzschild black holes: their entropy emission rates $\dot S_{\text{Sch}}$ are related to their energy emission rates $P$ by the simple relation $\dot S_{\text{Sch}}=C_{\text{Sch}}\times (P/\hbar)^{1/2}$. Remembering that $(1+1)$-dimensional perfect black-body emitters are characterized by the same functional relation, $\dot S^{1+1}=C^{1+1}\times(P/\hbar)^{1/2}$, Bekenstein and Mayo have concluded that, in their entropy emission properties, $(3+1)$-dimensional Schwarzschild black holes behave effectively as $(1+1)$-dimensional entropy emitters. One naturally wonders whether all black holes behave as simple $(1+1)$-dimensional entropy emitters? In order to address this interesting question, we shall study in this paper the entropy emission properties of Reissner-Nordstr\"om black holes. We shall show, in particular, that the physical properties which characterize the neutral sector of the Hawking emission spectra of these black holes can be studied {\it analytically} in the near-extremal $T_{\text{BH}}\to0$ regime. We find that the Hawking radiation spectra of massless neutral scalar fields and coupled electromagnetic-gravitational fields are characterized by the non-trivial entropy-energy relations $\dot S^{\text{Scalar}}_{\text{RN}} = -C^{\text{Scalar}}_{\text{RN}} \times (AP^3/\hbar^3)^{1/4} \ln(AP/\hbar)$ and $\dot S^{\text{Elec-Grav}}_{\text{RN}} = -C^{\text{Elec-Grav}}_{\text{RN}} \times (A^4P^9/\hbar^9)^{1/10} \ln(AP/\hbar)$ in the near-extremal $T_{\text{BH}}\to0$ limit (here $A$ is the surface area of the Reissner-Nordstr\"om black hole). Our analytical results therefore indicate that {\it not} all black holes behave as simple $(1+1)$-dimensional entropy emitters. |
1510.04155 | Saken Toktarbay | Saken Toktarbay and Hernando Quevedo | A stationary q-metric | 3 pages | null | 10.1134/S0202289314040136 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a stationary generalization of the static $q-$metric, the simplest
generalization of the Schwarzschild solution that contains a quadrupole
parameter. It possesses three independent parameters that are related to the
mass, quadrupole moment and angular momentum. We investigate the geometric and
physical properties of this exact solution of Einstein's vacuum equations, and
show that it can be used to describe the exterior gravitational field of
rotating, axially symmetric, compact objects.
| [
{
"created": "Wed, 14 Oct 2015 15:35:50 GMT",
"version": "v1"
}
] | 2015-10-15 | [
[
"Toktarbay",
"Saken",
""
],
[
"Quevedo",
"Hernando",
""
]
] | We present a stationary generalization of the static $q-$metric, the simplest generalization of the Schwarzschild solution that contains a quadrupole parameter. It possesses three independent parameters that are related to the mass, quadrupole moment and angular momentum. We investigate the geometric and physical properties of this exact solution of Einstein's vacuum equations, and show that it can be used to describe the exterior gravitational field of rotating, axially symmetric, compact objects. |
gr-qc/0105058 | Roy Maartens | Laszlo Gergely (Szeged), Roy Maartens (Portsmouth) | Brane-world generalizations of the Einstein static universe | additional interpretation of new solutions; accepted by
Class.Quant.Grav | Class.Quant.Grav. 19 (2002) 213-222 | 10.1088/0264-9381/19/2/303 | null | gr-qc astro-ph hep-th | null | A static Friedmann brane in a 5-dimensional bulk (Randall-Sundrum type
scenario) can have a very different relation between the density, pressure,
curvature and cosmological constant than in the case of the general
relativistic Einstein static universe. In particular, static Friedmann branes
with zero cosmological constant and 3-curvature, but satisfying rho>0 and
rho+3p>0, are possible. Furthermore, we find static Friedmann branes in a bulk
that satisfies the Einstein equations but is not Schwarzschild-anti de Sitter
or its specializations. In the models with negative bulk cosmological constant,
a positive brane tension leads to negative density and 3-curvature.
| [
{
"created": "Thu, 17 May 2001 15:54:33 GMT",
"version": "v1"
},
{
"created": "Wed, 5 Dec 2001 08:14:39 GMT",
"version": "v2"
}
] | 2009-11-07 | [
[
"Gergely",
"Laszlo",
"",
"Szeged"
],
[
"Maartens",
"Roy",
"",
"Portsmouth"
]
] | A static Friedmann brane in a 5-dimensional bulk (Randall-Sundrum type scenario) can have a very different relation between the density, pressure, curvature and cosmological constant than in the case of the general relativistic Einstein static universe. In particular, static Friedmann branes with zero cosmological constant and 3-curvature, but satisfying rho>0 and rho+3p>0, are possible. Furthermore, we find static Friedmann branes in a bulk that satisfies the Einstein equations but is not Schwarzschild-anti de Sitter or its specializations. In the models with negative bulk cosmological constant, a positive brane tension leads to negative density and 3-curvature. |
2303.17283 | Tuan Do | Tuan Q. Do, Duy H. Nguyen, Tuyen M. Pham | Stability investigations of isotropic and anisotropic exponential
inflation in the Starobinsky-Bel-Robinson gravity | 32 pages, 3 figures. V3 with many discussions, calculations, and
relevant references added. Accepted for publication by International Journal
of Modern Physics D. Comments are welcome | International Journal of Modern Physics D 32, 2350087 (2023) | 10.1142/S0218271823500876 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we would like to examine whether a novel
Starobinsky-Bel-Robinson gravity model admits stable exponential inflationary
solutions with or without spatial anisotropies. As a result, we are able to
derive an exact de Sitter inflationary to this Starobinsky-Bel-Robinson model.
Furthermore, we observe that an exact Bianchi type I inflationary solution does
not exist in the Starobinsky-Bel-Robinson model. However, we find that a
modified Starobinsky-Bel-Robinson model, in which the sign of coefficient of
$R^2$ term is flipped from positive to negative, can admit the corresponding
Bianchi type I inflationary solution. Unfortunately, stability analysis using
the dynamical system approach indicates that both of these inflationary
solutions turn out to be unstable. Interestingly, we show that a stable de
Sitter inflationary solution can be obtained in the modified
Starobinsky-Bel-Robinson gravity.
| [
{
"created": "Thu, 30 Mar 2023 10:45:03 GMT",
"version": "v1"
},
{
"created": "Thu, 6 Apr 2023 13:32:03 GMT",
"version": "v2"
},
{
"created": "Thu, 30 Nov 2023 03:48:31 GMT",
"version": "v3"
}
] | 2023-12-01 | [
[
"Do",
"Tuan Q.",
""
],
[
"Nguyen",
"Duy H.",
""
],
[
"Pham",
"Tuyen M.",
""
]
] | In this paper, we would like to examine whether a novel Starobinsky-Bel-Robinson gravity model admits stable exponential inflationary solutions with or without spatial anisotropies. As a result, we are able to derive an exact de Sitter inflationary to this Starobinsky-Bel-Robinson model. Furthermore, we observe that an exact Bianchi type I inflationary solution does not exist in the Starobinsky-Bel-Robinson model. However, we find that a modified Starobinsky-Bel-Robinson model, in which the sign of coefficient of $R^2$ term is flipped from positive to negative, can admit the corresponding Bianchi type I inflationary solution. Unfortunately, stability analysis using the dynamical system approach indicates that both of these inflationary solutions turn out to be unstable. Interestingly, we show that a stable de Sitter inflationary solution can be obtained in the modified Starobinsky-Bel-Robinson gravity. |
1808.08154 | Massimiliano Rinaldi | Massimiliano Rinaldi | On the equivalence of Jordan and Einstein frames in scale-invariant
gravity | 6 pages, revtex. Accepted for publication in EPJPlus | Eur. Phys. J. Plus (2018) 133: 408 | 10.1140/epjp/i2018-12213-9 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this note we consider the issue of the classical equivalence of
scale-invariant gravity in the Einstein and in the Jordan frames. We first
consider the simplest example $f(R)=R^{2}$ and show explicitly that the
equivalence breaks down when dealing with Ricci-flat solutions. We discuss the
link with the fact that flat solutions in quadratic gravity have zero energy.
We also consider the case of scale-invariant tensor-scalar gravity and general
$f(R)$ theories. We argue that all scale-invariant gravity models have Ricci
flat solutions in the Jordan frame that cannot be mapped into the Einstein
frame. In particular, the Minkowski metric exists only in the Jordan frame. In
this sense, the two frames are not equivalent.
| [
{
"created": "Fri, 24 Aug 2018 14:23:08 GMT",
"version": "v1"
}
] | 2018-10-09 | [
[
"Rinaldi",
"Massimiliano",
""
]
] | In this note we consider the issue of the classical equivalence of scale-invariant gravity in the Einstein and in the Jordan frames. We first consider the simplest example $f(R)=R^{2}$ and show explicitly that the equivalence breaks down when dealing with Ricci-flat solutions. We discuss the link with the fact that flat solutions in quadratic gravity have zero energy. We also consider the case of scale-invariant tensor-scalar gravity and general $f(R)$ theories. We argue that all scale-invariant gravity models have Ricci flat solutions in the Jordan frame that cannot be mapped into the Einstein frame. In particular, the Minkowski metric exists only in the Jordan frame. In this sense, the two frames are not equivalent. |
0805.1451 | James Isenberg | Vincent Moncrief, James Isenberg | Symmetries of Higher Dimensional Black Holes | 57 pages | Class.Quant.Grav.25:195015,2008 | 10.1088/0264-9381/25/19/195015 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We prove that if a stationary, real analytic, asymptotically flat vacuum
black hole spacetime of dimension $n\geq 4$ contains a non-degenerate horizon
with compact cross sections that are transverse to the stationarity generating
Killing vector field then, for each connected component of the black hole's
horizon, there is a Killing field which is tangent to the generators of the
horizon. For the case of rotating black holes, the stationarity generating
Killing field is not tangent to the horizon generators and therefore the
isometry group of the spacetime is at least two dimensional. Our proof relies
on significant extensions of our earlier work on the symmetries of spacetimes
containing a compact Cauchy horizon, allowing now for non closed generators of
the horizon.
| [
{
"created": "Sat, 10 May 2008 06:41:15 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Moncrief",
"Vincent",
""
],
[
"Isenberg",
"James",
""
]
] | We prove that if a stationary, real analytic, asymptotically flat vacuum black hole spacetime of dimension $n\geq 4$ contains a non-degenerate horizon with compact cross sections that are transverse to the stationarity generating Killing vector field then, for each connected component of the black hole's horizon, there is a Killing field which is tangent to the generators of the horizon. For the case of rotating black holes, the stationarity generating Killing field is not tangent to the horizon generators and therefore the isometry group of the spacetime is at least two dimensional. Our proof relies on significant extensions of our earlier work on the symmetries of spacetimes containing a compact Cauchy horizon, allowing now for non closed generators of the horizon. |
gr-qc/9608033 | Jorge Pullin | Hugo Fort, Rodolfo Gambini and Jorge Pullin | Lattice knot theory and quantum gravity in the loop representation | 23 pages, RevTeX, 14 figures included with psfig | Phys.Rev. D56 (1997) 2127-2143 | 10.1103/PhysRevD.56.2127 | CGPG-96/8-1, ESI-368 | gr-qc hep-lat hep-th math.QA q-alg | null | We present an implementation of the loop representation of quantum gravity on
a square lattice. Instead of starting from a classical lattice theory,
quantizing and introducing loops, we proceed backwards, setting up constraints
in the lattice loop representation and showing that they have appropriate
(singular) continuum limits and algebras. The diffeomorphism constraint
reproduces the classical algebra in the continuum and has as solutions lattice
analogues of usual knot invariants. We discuss some of the invariants stemming
from Chern--Simons theory in the lattice context, including the issue of
framing. We also present a regularization of the Hamiltonian constraint. We
show that two knot invariants from Chern--Simons theory are annihilated by the
Hamiltonian constraint through the use of their skein relations, including
intersections. We also discuss the issue of intersections with kinks. This
paper is the first step towards setting up the loop representation in a
rigorous, computable setting.
| [
{
"created": "Wed, 14 Aug 1996 19:18:34 GMT",
"version": "v1"
}
] | 2009-10-28 | [
[
"Fort",
"Hugo",
""
],
[
"Gambini",
"Rodolfo",
""
],
[
"Pullin",
"Jorge",
""
]
] | We present an implementation of the loop representation of quantum gravity on a square lattice. Instead of starting from a classical lattice theory, quantizing and introducing loops, we proceed backwards, setting up constraints in the lattice loop representation and showing that they have appropriate (singular) continuum limits and algebras. The diffeomorphism constraint reproduces the classical algebra in the continuum and has as solutions lattice analogues of usual knot invariants. We discuss some of the invariants stemming from Chern--Simons theory in the lattice context, including the issue of framing. We also present a regularization of the Hamiltonian constraint. We show that two knot invariants from Chern--Simons theory are annihilated by the Hamiltonian constraint through the use of their skein relations, including intersections. We also discuss the issue of intersections with kinks. This paper is the first step towards setting up the loop representation in a rigorous, computable setting. |
0804.1686 | Ralf Schutzhold | Ralf Sch\"utzhold and William G. Unruh | On the origin of the particles in black hole evaporation | 4 pages RevTex | Phys.Rev.D78:041504,2008 | 10.1103/PhysRevD.78.041504 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present an analytic derivation of Hawking radiation for an arbitrary
(spatial) dispersion relation $\omega(k)$ as a model for ultra-high energy
deviations from general covariance. It turns out that the Hawking temperature
is proportional to the product of the group $d\omega/dk$ and phase $\omega/k$
velocities evaluated at the frequency $\omega$ of the outgoing radiation far
away, which suggests that Hawking radiation is basically a low-energy
phenomenon. Nevertheless, a group velocity growing too fast at ultra-short
distances would generate Hawking radiation at ultra-high energies
(``ultra-violet catastrophe'') and hence should not be a realistic model for
the microscopic structure of quantum gravity.
| [
{
"created": "Thu, 10 Apr 2008 12:30:24 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Schützhold",
"Ralf",
""
],
[
"Unruh",
"William G.",
""
]
] | We present an analytic derivation of Hawking radiation for an arbitrary (spatial) dispersion relation $\omega(k)$ as a model for ultra-high energy deviations from general covariance. It turns out that the Hawking temperature is proportional to the product of the group $d\omega/dk$ and phase $\omega/k$ velocities evaluated at the frequency $\omega$ of the outgoing radiation far away, which suggests that Hawking radiation is basically a low-energy phenomenon. Nevertheless, a group velocity growing too fast at ultra-short distances would generate Hawking radiation at ultra-high energies (``ultra-violet catastrophe'') and hence should not be a realistic model for the microscopic structure of quantum gravity. |
1810.03080 | Hamid Reza Sepangi | A. Rahmani, M. Honardoost, H. R. Sepangi | Superradiant instability and asymptotically AdS hairy black holes in
$F(R)$-charged scalar field theory | 23 pages, 12 figures, to appear in GERG | Gen Relativ Gravit 52, 53 (2020) | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the phenomena of superradiance for $F(R)$-Maxwell black holes in an
AdS space-time. The AdS boundary plays the role of a mirror and provides a
natural confining system that makes the superradiant waves bouncing back and
forth between the region near the horizon and the reflective boundary, causing
a possible superradiant instability. We obtain numerical solutions for static
hairy black holes in this scenario and investigate their instability and
explicitly address the stability of such solutions for spherical perturbations
under specific conditions for the scalar charge and AdS radius. It is shown
that for a small scalar charge or AdS radius the static hairy solution is
stable under spherical perturbations. We conclude that under such conditions,
new hairy black holes emerge as a possible endpoint of superradiant instability
of the system.
| [
{
"created": "Sun, 7 Oct 2018 03:39:51 GMT",
"version": "v1"
},
{
"created": "Tue, 5 Feb 2019 08:40:58 GMT",
"version": "v2"
},
{
"created": "Mon, 11 Mar 2019 11:06:51 GMT",
"version": "v3"
},
{
"created": "Sun, 7 Jul 2019 02:45:10 GMT",
"version": "v4"
},
{
"created": "Tue, 26 May 2020 05:15:20 GMT",
"version": "v5"
}
] | 2020-06-02 | [
[
"Rahmani",
"A.",
""
],
[
"Honardoost",
"M.",
""
],
[
"Sepangi",
"H. R.",
""
]
] | We study the phenomena of superradiance for $F(R)$-Maxwell black holes in an AdS space-time. The AdS boundary plays the role of a mirror and provides a natural confining system that makes the superradiant waves bouncing back and forth between the region near the horizon and the reflective boundary, causing a possible superradiant instability. We obtain numerical solutions for static hairy black holes in this scenario and investigate their instability and explicitly address the stability of such solutions for spherical perturbations under specific conditions for the scalar charge and AdS radius. It is shown that for a small scalar charge or AdS radius the static hairy solution is stable under spherical perturbations. We conclude that under such conditions, new hairy black holes emerge as a possible endpoint of superradiant instability of the system. |
gr-qc/0404120 | Joel Franklin | S. Deser, J. Franklin, B. Tekin | Shortcuts to Spherically Symmetric Solutions: A Cautionary Note | 2 pages. Amplified derivation, accepted for publication in Class
Quant Grav | Class.Quant.Grav.21:5295-5296,2004 | 10.1088/0264-9381/21/22/N01 | null | gr-qc | null | Spherically symmetric solutions of generic gravitational models are
optimally, and legitimately, obtained by expressing the action in terms of the
two surviving metric components. This shortcut is not to be overdone, however:
a one-function ansatz invalidates it, as illustrated by the incorrect solutions
of [1].
| [
{
"created": "Wed, 28 Apr 2004 21:05:56 GMT",
"version": "v1"
},
{
"created": "Sun, 26 Sep 2004 17:40:02 GMT",
"version": "v2"
}
] | 2008-11-26 | [
[
"Deser",
"S.",
""
],
[
"Franklin",
"J.",
""
],
[
"Tekin",
"B.",
""
]
] | Spherically symmetric solutions of generic gravitational models are optimally, and legitimately, obtained by expressing the action in terms of the two surviving metric components. This shortcut is not to be overdone, however: a one-function ansatz invalidates it, as illustrated by the incorrect solutions of [1]. |
2006.09156 | John Klauder | John R. Klauder | Using Affine Quantization to Analyze Non-renormalizable Scalar Fields
and the Quantization of Einstein's Gravity | 19 pages; Carefully choosing favored variables to promote to
operators, featuring non-renormalizable scalar fields and quantum gravity | null | null | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Affine quantization is a parallel procedure to canonical quantization, which
is ideally suited to deal with non-renormalizable scalar models as well as
quantum gravity. The basic applications of this approach lead to the common
goals of any quantization, such as Schroedinger's representation and
Schroedinger's equation. Careful attention is paid toward seeking favored
classical variables, which are those that should be promoted to the principal
quantum operators. This effort leads toward classical variables that have a
constant positive, zero, or negative curvature, which typically characterize
such favored variables. This focus leans heavily toward affine variables with a
constant negative curvature, which leads to a surprisingly accommodating
analysis of non-renormalizable scalar models as well as Einstein's general
relativity.
| [
{
"created": "Tue, 16 Jun 2020 13:59:37 GMT",
"version": "v1"
}
] | 2020-06-17 | [
[
"Klauder",
"John R.",
""
]
] | Affine quantization is a parallel procedure to canonical quantization, which is ideally suited to deal with non-renormalizable scalar models as well as quantum gravity. The basic applications of this approach lead to the common goals of any quantization, such as Schroedinger's representation and Schroedinger's equation. Careful attention is paid toward seeking favored classical variables, which are those that should be promoted to the principal quantum operators. This effort leads toward classical variables that have a constant positive, zero, or negative curvature, which typically characterize such favored variables. This focus leans heavily toward affine variables with a constant negative curvature, which leads to a surprisingly accommodating analysis of non-renormalizable scalar models as well as Einstein's general relativity. |
1607.02698 | Ryosuke Mizuno | Ryosuke Mizuno, Seiju Ohashi, Tetsuya Shiromizu | Violation of cosmic censorship in the gravitational collapse of a dust
cloud in five dimension | 37 pages | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We analyze the null geodesic equations in five dimensional spherically
symmetric spacetime with collapsing inhomogeneous dust cloud. By using a new
method, we prove the existence and non-existence of solutions to null geodesic
equation emanating from central singularity for smooth initial distribution of
dust. Moreover, we also show that the null geodesics can extend to null
infinity in a certain case, which imply the violation of cosmic censorship
conjecture.
| [
{
"created": "Sun, 10 Jul 2016 06:29:33 GMT",
"version": "v1"
}
] | 2016-07-12 | [
[
"Mizuno",
"Ryosuke",
""
],
[
"Ohashi",
"Seiju",
""
],
[
"Shiromizu",
"Tetsuya",
""
]
] | We analyze the null geodesic equations in five dimensional spherically symmetric spacetime with collapsing inhomogeneous dust cloud. By using a new method, we prove the existence and non-existence of solutions to null geodesic equation emanating from central singularity for smooth initial distribution of dust. Moreover, we also show that the null geodesics can extend to null infinity in a certain case, which imply the violation of cosmic censorship conjecture. |
2311.04025 | Liu Zhao | Tao Wang, Yifan Cai, Long Cui and Liu Zhao | General relativistic stochastic thermodynamics | 15 pages, 1 figure | null | null | null | gr-qc cond-mat.stat-mech | http://creativecommons.org/licenses/by/4.0/ | Based on the recent work [1,2], we formulate the first law and the second law
of stochastic thermodynamics in the framework of general relativity. These laws
are established for a charged Brownian particle moving in a heat reservoir and
subjecting to an external electromagnetic field in generic stationary spacetime
background, and in order to maintain general covariance, they are presented
respectively in terms of the divergences of the energy current and the entropy
density current. The stability of the equilibrium state is also analyzed.
| [
{
"created": "Tue, 7 Nov 2023 14:24:34 GMT",
"version": "v1"
}
] | 2023-11-08 | [
[
"Wang",
"Tao",
""
],
[
"Cai",
"Yifan",
""
],
[
"Cui",
"Long",
""
],
[
"Zhao",
"Liu",
""
]
] | Based on the recent work [1,2], we formulate the first law and the second law of stochastic thermodynamics in the framework of general relativity. These laws are established for a charged Brownian particle moving in a heat reservoir and subjecting to an external electromagnetic field in generic stationary spacetime background, and in order to maintain general covariance, they are presented respectively in terms of the divergences of the energy current and the entropy density current. The stability of the equilibrium state is also analyzed. |
0912.2724 | Nicolas Yunes | Nicolas Yunes, Frans Pretorius and David Spergel | Constraining the evolutionary history of Newton's constant with
gravitational wave observations | 11 pages, 2 figures, replaced with version accepted for publication
in Phys. Rev. D. | Phys.Rev.D81:064018,2010 | 10.1103/PhysRevD.81.064018 | null | gr-qc astro-ph.CO astro-ph.HE hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Space-borne gravitational wave detectors, such as the proposed Laser
Interferometer Space Antenna, are expected to observe black hole coalescences
to high redshift and with large signal-to-noise ratios, rendering their
gravitational waves ideal probes of fundamental physics. The promotion of
Newton's constant to a time-function introduces modifications to the binary's
binding energy and the gravitational wave luminosity, leading to corrections in
the chirping frequency. Such corrections propagate into the response function
and, given a gravitational wave observation, they allow for constraints on the
first time-derivative of Newton's constant at the time of merger. We find that
space-borne detectors could indeed place interesting constraints on this
quantity as a function of sky position and redshift, providing a
{\emph{constraint map}} over the entire range of redshifts where binary black
hole mergers are expected to occur. A LISA observation of an equal-mass
inspiral event with total redshifted mass of 10^5 solar masses for three years
should be able to measure $\dot{G}/G$ at the time of merger to better than
10^(-11)/yr.
| [
{
"created": "Tue, 15 Dec 2009 16:44:02 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Apr 2010 18:43:40 GMT",
"version": "v2"
}
] | 2010-04-29 | [
[
"Yunes",
"Nicolas",
""
],
[
"Pretorius",
"Frans",
""
],
[
"Spergel",
"David",
""
]
] | Space-borne gravitational wave detectors, such as the proposed Laser Interferometer Space Antenna, are expected to observe black hole coalescences to high redshift and with large signal-to-noise ratios, rendering their gravitational waves ideal probes of fundamental physics. The promotion of Newton's constant to a time-function introduces modifications to the binary's binding energy and the gravitational wave luminosity, leading to corrections in the chirping frequency. Such corrections propagate into the response function and, given a gravitational wave observation, they allow for constraints on the first time-derivative of Newton's constant at the time of merger. We find that space-borne detectors could indeed place interesting constraints on this quantity as a function of sky position and redshift, providing a {\emph{constraint map}} over the entire range of redshifts where binary black hole mergers are expected to occur. A LISA observation of an equal-mass inspiral event with total redshifted mass of 10^5 solar masses for three years should be able to measure $\dot{G}/G$ at the time of merger to better than 10^(-11)/yr. |
gr-qc/9412062 | Ed Seidel | Edward Seidel, Wai-Mo Suen | Formation gf Bosonic Compact Objects | 3 pages, uuencoded gziped ps file. Also available at
http://jean-luc.ncsa.uiuc.edu/Papers/ To appear in the MG7 proceedings | null | null | null | gr-qc | null | We showed that compact bosonic objects can be formed through a process we
called gravitational cooling. A central issue in the subject of boson star is
whether a classical field configuration, {\it e.g.,} one described by the
Klein-Gordon equation, can collapse to form a compact star-like object, as
there is apparently no dissipation in the Klein-Gordon equation. We
demonstrated that there IS an efficient cooling mechanism to get rid of the
kinetic energy for the formation of a compact object purely through the
gravitational coupling, a mechanism universal to all self-graviting fields.
Implications of this mechanism are discussed, including the abundance of
bosonic stars in the universe, and the possibility of ruling out the axion as a
dark matter condidate.
| [
{
"created": "Wed, 21 Dec 1994 01:42:06 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Seidel",
"Edward",
""
],
[
"Suen",
"Wai-Mo",
""
]
] | We showed that compact bosonic objects can be formed through a process we called gravitational cooling. A central issue in the subject of boson star is whether a classical field configuration, {\it e.g.,} one described by the Klein-Gordon equation, can collapse to form a compact star-like object, as there is apparently no dissipation in the Klein-Gordon equation. We demonstrated that there IS an efficient cooling mechanism to get rid of the kinetic energy for the formation of a compact object purely through the gravitational coupling, a mechanism universal to all self-graviting fields. Implications of this mechanism are discussed, including the abundance of bosonic stars in the universe, and the possibility of ruling out the axion as a dark matter condidate. |
gr-qc/0506125 | Satheesh Kumar V H | V H Satheesh Kumar and P K Suresh | Are We Living in a Higher Dimensional Universe? | 21 pages, 5 figures. New reference is added with minor modification | null | null | null | gr-qc hep-ph hep-th | null | It is a brief review of the physical theories embodying the idea of extra
dimensions, starting from the pre-historic times to the present day. Here we
have classified the developments into three eras, such as Pre-Einstein,
Einstein and Kaluza-Klein. Here the views and flow of thoughts are emphasized
rather rigorous mathematical details. Majour developments in Quantum field
theory and Particle physics are outlined. Some well known higher dimensional
approaches to unification are discussed. This is concluded with some examples
for visualizing extra dimensions and a short discussion on the cosmological
implications and possible existence of the same.
| [
{
"created": "Tue, 28 Jun 2005 08:02:50 GMT",
"version": "v1"
},
{
"created": "Fri, 8 Jul 2005 05:53:40 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Kumar",
"V H Satheesh",
""
],
[
"Suresh",
"P K",
""
]
] | It is a brief review of the physical theories embodying the idea of extra dimensions, starting from the pre-historic times to the present day. Here we have classified the developments into three eras, such as Pre-Einstein, Einstein and Kaluza-Klein. Here the views and flow of thoughts are emphasized rather rigorous mathematical details. Majour developments in Quantum field theory and Particle physics are outlined. Some well known higher dimensional approaches to unification are discussed. This is concluded with some examples for visualizing extra dimensions and a short discussion on the cosmological implications and possible existence of the same. |
1705.09836 | Patryk Drobi\'nski | Patryk Drobi\'nski, Jerzy Lewandowski | The continuum approach to the BF vacuum: the U(1) case | 13 pages | Phys. Rev. D 96, 126011 (2017) | 10.1103/PhysRevD.96.126011 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A quantum representation of holonomies and exponentiated fluxes of a $U(1)$
gauge theory that contains the Pullin-Dittrich-Geiller (DG) vacuum is presented
and discussed. Our quantization is performed manifestly in a continuum theory,
without any discretization. The discretness emerges on the quantum level as a
property of the spectrum of the quantum holonomy operators. The new type of a
cylindrical consistency present in the DG approach, now follows easily and
naturally. A generalization to the non--Abelian case seems possible.
| [
{
"created": "Sat, 27 May 2017 16:16:25 GMT",
"version": "v1"
},
{
"created": "Tue, 28 Nov 2017 09:34:49 GMT",
"version": "v2"
}
] | 2017-12-27 | [
[
"Drobiński",
"Patryk",
""
],
[
"Lewandowski",
"Jerzy",
""
]
] | A quantum representation of holonomies and exponentiated fluxes of a $U(1)$ gauge theory that contains the Pullin-Dittrich-Geiller (DG) vacuum is presented and discussed. Our quantization is performed manifestly in a continuum theory, without any discretization. The discretness emerges on the quantum level as a property of the spectrum of the quantum holonomy operators. The new type of a cylindrical consistency present in the DG approach, now follows easily and naturally. A generalization to the non--Abelian case seems possible. |
2310.08160 | Tao Yang | Tao Yang, Rong-Gen Cai, Zhoujian Cao, Hyung Mok Lee | Eccentricity enables the earliest warning and localization of
gravitational waves with ground-based detectors | 8 pages, 2 figures, published in PRD | Phys.Rev.D 109 (2024) 104041 | 10.1103/PhysRevD.109.104041 | null | gr-qc astro-ph.CO astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The early and precise localization of gravitational waves (GWs) is pivotal in
detecting their electromagnetic (EM) counterparts, especially for binary
neutron stars (BNS) and neutron star-black hole binaries (NSBH). In this
letter, we pioneer the exploration of utilizing the higher harmonic modes
induced by the eccentricity of compact binaries to localize GWs with
ground-based detectors even before the quadrupole baseline $\ell=2$ mode enters
the detector band. Our theoretical analysis marks a first in proposing a
strategy for gaining the earliest possible warning and maximizing preparation
time for observing pre- and/or post-merger EM counterparts. We simulate three
typical binaries from GWTC-3 with eccentricities ranging from 0.05 to 0.4. Our
results reveal that the third-generation (3G) detectors (low frequency cut-off
$f_0=5$ Hz) can accumulate sufficient signal-to-noise ratios through higher
modes before the onset of the baseline $\ell=2$ mode entry into the band.
Notably, relying solely on the higher modes, the 3G detector network ET+2CE
achieves an average localization on the order of $1-10^2~\rm deg^2$ around
1-1.8 hours before the merger of a GW170817-like BNS, and $10-10^3~\rm deg^2$
approximately 18-30 minutes prior to the merger of a GW200115-like NSBH. A
$100~\rm deg^2$ localization is attainable even 2-4 hours prior to a BNS
merger. Moreover, in the near face-on orientations which are generally more
favorable for EM counterpart detection, the localization can be further
improved.
| [
{
"created": "Thu, 12 Oct 2023 09:29:45 GMT",
"version": "v1"
},
{
"created": "Tue, 14 May 2024 01:25:17 GMT",
"version": "v2"
}
] | 2024-05-15 | [
[
"Yang",
"Tao",
""
],
[
"Cai",
"Rong-Gen",
""
],
[
"Cao",
"Zhoujian",
""
],
[
"Lee",
"Hyung Mok",
""
]
] | The early and precise localization of gravitational waves (GWs) is pivotal in detecting their electromagnetic (EM) counterparts, especially for binary neutron stars (BNS) and neutron star-black hole binaries (NSBH). In this letter, we pioneer the exploration of utilizing the higher harmonic modes induced by the eccentricity of compact binaries to localize GWs with ground-based detectors even before the quadrupole baseline $\ell=2$ mode enters the detector band. Our theoretical analysis marks a first in proposing a strategy for gaining the earliest possible warning and maximizing preparation time for observing pre- and/or post-merger EM counterparts. We simulate three typical binaries from GWTC-3 with eccentricities ranging from 0.05 to 0.4. Our results reveal that the third-generation (3G) detectors (low frequency cut-off $f_0=5$ Hz) can accumulate sufficient signal-to-noise ratios through higher modes before the onset of the baseline $\ell=2$ mode entry into the band. Notably, relying solely on the higher modes, the 3G detector network ET+2CE achieves an average localization on the order of $1-10^2~\rm deg^2$ around 1-1.8 hours before the merger of a GW170817-like BNS, and $10-10^3~\rm deg^2$ approximately 18-30 minutes prior to the merger of a GW200115-like NSBH. A $100~\rm deg^2$ localization is attainable even 2-4 hours prior to a BNS merger. Moreover, in the near face-on orientations which are generally more favorable for EM counterpart detection, the localization can be further improved. |
1306.4775 | Sergey Stepanov | S.S. Stepanov | Are rigid non-inertial frames of reference really rigid? | in Russian, 4 figures | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper the notion of the rigid frame of reference within special
relativity is analysed. Three definitions of rigidity are formulated. By using
several examples of non-inertial frames, it is shown that these definitions are
not equivalent. It is also shown that so called M\"oller rigid non-inertial
frames are locally rigid, but do not exhibit global rigidity. The physical
meaning of this phenomenon is discussed, as well as its relation to the
non-Euclidean nature of space in non-inertial frames of reference. (russian
version)
| [
{
"created": "Thu, 20 Jun 2013 07:39:33 GMT",
"version": "v1"
}
] | 2013-06-21 | [
[
"Stepanov",
"S. S.",
""
]
] | In this paper the notion of the rigid frame of reference within special relativity is analysed. Three definitions of rigidity are formulated. By using several examples of non-inertial frames, it is shown that these definitions are not equivalent. It is also shown that so called M\"oller rigid non-inertial frames are locally rigid, but do not exhibit global rigidity. The physical meaning of this phenomenon is discussed, as well as its relation to the non-Euclidean nature of space in non-inertial frames of reference. (russian version) |
2112.04206 | Chenghu Ge | Rong-Gen Cai, Chenghu Ge, Li Li, Run-Qiu Yang | Inside Anisotropic Black Hole with Vector Hair | v3:typos fixed, published version | JHEP 02(2022)139 | 10.1007/JHEP02(2022)139 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the internal structure of anisotropic black holes with charged
vector hairs. Taking advantage of the scaling symmetries of the system, some
radially conserved charges are found via the extension of the Noether theorem.
Then, a general proof of no inner horizon of these black holes is presented and
the geometry ends at a spacelike singularity. Before reaching the singularity,
we find several intermediate regimes both analytically and numerically. In
addition to the Einstein-Rosen bridge contracting towards the singularity, the
instability triggered by the vector hair results in the oscillations of vector
condensate and the anisotropy of spatial geometry. Moreover, the latter
oscillates at twice the frequency of the condensate. Then, the geometry enters
into Kasner epochs with spatial anisotropy. Due to the effects from vector
condensate and U(1) gauge potential, there is generically a never-ending
alternation of Kasner epochs towards the singularity. The character of
evolution on approaching the singularity is found to be described by the Kasner
epoch alternation with flipping of powers of the Belinskii-Khalatnikov-Lifshitz
type.
| [
{
"created": "Wed, 8 Dec 2021 10:12:16 GMT",
"version": "v1"
},
{
"created": "Thu, 16 Dec 2021 10:14:17 GMT",
"version": "v2"
},
{
"created": "Tue, 22 Feb 2022 01:46:33 GMT",
"version": "v3"
}
] | 2022-02-23 | [
[
"Cai",
"Rong-Gen",
""
],
[
"Ge",
"Chenghu",
""
],
[
"Li",
"Li",
""
],
[
"Yang",
"Run-Qiu",
""
]
] | We study the internal structure of anisotropic black holes with charged vector hairs. Taking advantage of the scaling symmetries of the system, some radially conserved charges are found via the extension of the Noether theorem. Then, a general proof of no inner horizon of these black holes is presented and the geometry ends at a spacelike singularity. Before reaching the singularity, we find several intermediate regimes both analytically and numerically. In addition to the Einstein-Rosen bridge contracting towards the singularity, the instability triggered by the vector hair results in the oscillations of vector condensate and the anisotropy of spatial geometry. Moreover, the latter oscillates at twice the frequency of the condensate. Then, the geometry enters into Kasner epochs with spatial anisotropy. Due to the effects from vector condensate and U(1) gauge potential, there is generically a never-ending alternation of Kasner epochs towards the singularity. The character of evolution on approaching the singularity is found to be described by the Kasner epoch alternation with flipping of powers of the Belinskii-Khalatnikov-Lifshitz type. |
gr-qc/9808016 | Adrian Kent | Adrian Kent | Consistent Sets and Contrary Inferences: Reply to Griffiths and Hartle | 4 pages, TeX with harvmac; typo fixed. To appear in Phys. Rev. Lett | Phys.Rev.Lett. 81 (1998) 1982 | 10.1103/PhysRevLett.81.1982 | DAMTP-97/126 | gr-qc hep-th quant-ph | null | It was pointed out recently [A. Kent, Phys. Rev. Lett. 78 (1997) 2874] that
the consistent histories approach allows contrary inferences to be made from
the same data. These inferences correspond to projections $P$ and $Q$,
belonging to different consistent sets, with the properties that $PQ = QP = 0$
and $P \neq 1 -Q$. To many, this seems undesirable in a theory of physical
inferences. It also raises a specific problem for the consistent histories
formalism, since that formalism is set up so as to eliminate contradictory
inferences, i.e. inferences $P$ and $Q$ where $P = 1 - Q$. Yet there seems to
be no sensible physical distinction between contradictory and contrary
inferences.
It seems particularly hard to defend the asymmetry, since (i) there is a
well-defined quantum histories formalisms which admits both contradictory and
contrary inferences, and (ii) there is also a well-defined formalism, based on
ordered consistent sets of histories, which excludes both.
In a recent comment, Griffiths and Hartle, while accepting the validity of
the examples given in the above paper, restate their own preference for the
consistent histories formalism. As this brief reply explains, in so doing, they
fail to address the arguments made against their approach to quantum theory.
| [
{
"created": "Wed, 5 Aug 1998 14:55:24 GMT",
"version": "v1"
},
{
"created": "Fri, 14 Aug 1998 20:05:16 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Kent",
"Adrian",
""
]
] | It was pointed out recently [A. Kent, Phys. Rev. Lett. 78 (1997) 2874] that the consistent histories approach allows contrary inferences to be made from the same data. These inferences correspond to projections $P$ and $Q$, belonging to different consistent sets, with the properties that $PQ = QP = 0$ and $P \neq 1 -Q$. To many, this seems undesirable in a theory of physical inferences. It also raises a specific problem for the consistent histories formalism, since that formalism is set up so as to eliminate contradictory inferences, i.e. inferences $P$ and $Q$ where $P = 1 - Q$. Yet there seems to be no sensible physical distinction between contradictory and contrary inferences. It seems particularly hard to defend the asymmetry, since (i) there is a well-defined quantum histories formalisms which admits both contradictory and contrary inferences, and (ii) there is also a well-defined formalism, based on ordered consistent sets of histories, which excludes both. In a recent comment, Griffiths and Hartle, while accepting the validity of the examples given in the above paper, restate their own preference for the consistent histories formalism. As this brief reply explains, in so doing, they fail to address the arguments made against their approach to quantum theory. |
gr-qc/0403019 | Jose M. Martin-Garcia | Carsten Gundlach, Jose M. Martin-Garcia | Symmetric hyperbolicity and consistent boundary conditions for
second-order Einstein equations | 16 pages, 1 figure, revtex4 | Phys.Rev. D70 (2004) 044032 | 10.1103/PhysRevD.70.044032 | null | gr-qc | null | We present two families of first-order in time and second-order in space
formulations of the Einstein equations (variants of the Arnowitt-Deser-Misner
formulation) that admit a complete set of characteristic variables and a
conserved energy that can be expressed in terms of the characteristic
variables. The associated constraint system is also symmetric hyperbolic in
this sense, and all characteristic speeds are physical. We propose a family of
constraint-preserving boundary conditions that is applicable if the boundary is
smooth with tangential shift. We conjecture that the resulting initial-boundary
value problem is well-posed.
| [
{
"created": "Wed, 3 Mar 2004 18:33:22 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Gundlach",
"Carsten",
""
],
[
"Martin-Garcia",
"Jose M.",
""
]
] | We present two families of first-order in time and second-order in space formulations of the Einstein equations (variants of the Arnowitt-Deser-Misner formulation) that admit a complete set of characteristic variables and a conserved energy that can be expressed in terms of the characteristic variables. The associated constraint system is also symmetric hyperbolic in this sense, and all characteristic speeds are physical. We propose a family of constraint-preserving boundary conditions that is applicable if the boundary is smooth with tangential shift. We conjecture that the resulting initial-boundary value problem is well-posed. |
2304.08874 | Tuan Do | Tuan Q. Do, W. F. Kao | Anisotropic power-law inflation for a generalized model of two scalar
and two vector fields | 26 pages, 6 figures. Final version with some discussions and relevant
references added; typos fixed. All calculations remain unchanged. Accepted
for publication in Physica Scripta. Comments are welcome | Phys. Scr. 99, 015002 (2024) | 10.1088/1402-4896/ad0f82 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Cosmological implication of a generalized model of two scalar and two vector
fields, in which both scalar fields are non-minimally coupled to each vector
field, is studied in this paper. In particular, we will seek a set of new
anisotropic power-law inflationary solutions to this model. Additionally, the
stability of the obtained solutions will be examined by using the dynamical
system approach. As a result, we will show that this set of solutions turns out
to be stable and attractive during the inflationary phase as expected due to
the existence of the unusual couplings between two scalar and two vector
fields. Notably, we will point out that the existence of phantom field will
lead to an instability of the corresponding anisotropic power-law inflation.
| [
{
"created": "Tue, 18 Apr 2023 10:08:34 GMT",
"version": "v1"
},
{
"created": "Mon, 24 Apr 2023 10:07:40 GMT",
"version": "v2"
},
{
"created": "Fri, 28 Apr 2023 10:17:19 GMT",
"version": "v3"
},
{
"created": "Mon, 5 Feb 2024 03:53:04 GMT",
"version": "v4"
}
] | 2024-02-06 | [
[
"Do",
"Tuan Q.",
""
],
[
"Kao",
"W. F.",
""
]
] | Cosmological implication of a generalized model of two scalar and two vector fields, in which both scalar fields are non-minimally coupled to each vector field, is studied in this paper. In particular, we will seek a set of new anisotropic power-law inflationary solutions to this model. Additionally, the stability of the obtained solutions will be examined by using the dynamical system approach. As a result, we will show that this set of solutions turns out to be stable and attractive during the inflationary phase as expected due to the existence of the unusual couplings between two scalar and two vector fields. Notably, we will point out that the existence of phantom field will lead to an instability of the corresponding anisotropic power-law inflation. |
gr-qc/0006064 | Milan Stefanik | Milan Stefanik, Jan Horsky | The Kerr-Schild ansatz for the Nariai spacetime and the generating
conjecture | 5 pages,LaTeX | Acta Phys.Slov. 50 (2000) 213-218 | null | null | gr-qc | null | We will show that the Nariai metric, i.e. the static spherically symmetric
vacuum spacetime with a cosmological constant, admits a conformally Kerr-Schild
spacetime representation. We find the vacuum solutions of the Einstein-Maxwell
equations for the Nariai metric using the Horsky-Mitskievich generating
conjecture.
| [
{
"created": "Mon, 19 Jun 2000 10:04:06 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Stefanik",
"Milan",
""
],
[
"Horsky",
"Jan",
""
]
] | We will show that the Nariai metric, i.e. the static spherically symmetric vacuum spacetime with a cosmological constant, admits a conformally Kerr-Schild spacetime representation. We find the vacuum solutions of the Einstein-Maxwell equations for the Nariai metric using the Horsky-Mitskievich generating conjecture. |
1904.12783 | Katy Clough Dr | Katy Clough, Pedro G. Ferreira and Macarena Lagos | On the growth of massive scalar hair around a Schwarzschild black hole | 9 pages, 8 figures, updated to incorporate low mass cases and referee
suggestions | Phys. Rev. D 100, 063014 (2019) | 10.1103/PhysRevD.100.063014 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Through numerical simulations of a minimally coupled massive Klein-Gordon
scalar field, we show that it is possible to grow hair on a Schwarzschild black
hole if one assumes an initial periodically time-varying but spatially
homogeneous scalar background. By "hair", we mean a non-trivial profile in the
scalar field. We find that this profile emerges on a timescale related to the
mass of the black hole, with features related to the mass of the scalar
particle. We undertake simulations with and without backreaction on the metric
and see that the essential, qualitative features remain consistent. We also
contrast the results from higher mass scalars to the case of a low mass with a
large Compton wavelength. The results are particularly relevant for
scalar-tensor theories of gravity and dark matter models consisting of a
massive scalar, e.g. axions.
| [
{
"created": "Mon, 29 Apr 2019 15:51:38 GMT",
"version": "v1"
},
{
"created": "Mon, 9 Sep 2019 08:41:13 GMT",
"version": "v2"
}
] | 2019-10-02 | [
[
"Clough",
"Katy",
""
],
[
"Ferreira",
"Pedro G.",
""
],
[
"Lagos",
"Macarena",
""
]
] | Through numerical simulations of a minimally coupled massive Klein-Gordon scalar field, we show that it is possible to grow hair on a Schwarzschild black hole if one assumes an initial periodically time-varying but spatially homogeneous scalar background. By "hair", we mean a non-trivial profile in the scalar field. We find that this profile emerges on a timescale related to the mass of the black hole, with features related to the mass of the scalar particle. We undertake simulations with and without backreaction on the metric and see that the essential, qualitative features remain consistent. We also contrast the results from higher mass scalars to the case of a low mass with a large Compton wavelength. The results are particularly relevant for scalar-tensor theories of gravity and dark matter models consisting of a massive scalar, e.g. axions. |
1802.00590 | Hemza Azri | Hemza Azri and Durmus Demir | Induced Affine Inflation | 7 pages, 1 table and 3 figures, matches the published version | Phys. Rev. D 97 (2018), 044025 | 10.1103/PhysRevD.97.044025 | null | gr-qc astro-ph.HE hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Induced gravity, metrical gravity in which gravitational constant arises from
vacuum expectation value of a heavy scalar, is known to suffer from Jordan
frame vs. Einstein frame ambiguity, especially in inflationary dynamics.
Induced gravity in affine geometry, as we show here, leads to an emergent
metric and gravity scale, with no Einstein-Jordan ambiguity. While gravity is
induced by the vacuum expectation value of the scalar field, nonzero vacuum
energy facilitates generation of the metric. Our analysis shows that induced
gravity results in a relatively large tensor-to-scalar ratio in both metrical
and affine gravity setups. However, the fact remains that the induced affine
gravity provides an ambiguity-free framework.
| [
{
"created": "Fri, 2 Feb 2018 07:56:59 GMT",
"version": "v1"
},
{
"created": "Thu, 22 Feb 2018 07:46:25 GMT",
"version": "v2"
}
] | 2018-02-23 | [
[
"Azri",
"Hemza",
""
],
[
"Demir",
"Durmus",
""
]
] | Induced gravity, metrical gravity in which gravitational constant arises from vacuum expectation value of a heavy scalar, is known to suffer from Jordan frame vs. Einstein frame ambiguity, especially in inflationary dynamics. Induced gravity in affine geometry, as we show here, leads to an emergent metric and gravity scale, with no Einstein-Jordan ambiguity. While gravity is induced by the vacuum expectation value of the scalar field, nonzero vacuum energy facilitates generation of the metric. Our analysis shows that induced gravity results in a relatively large tensor-to-scalar ratio in both metrical and affine gravity setups. However, the fact remains that the induced affine gravity provides an ambiguity-free framework. |
gr-qc/0011053 | David A. Lowe | David A. Lowe | Yes, semiclassical zero temperature black holes exist | 1 page, revtex | Phys.Rev.Lett. 87 (2001) 029001 | 10.1103/PhysRevLett.87.029001 | null | gr-qc | null | In a recent paper (gr-qc/0002007), Anderson, Hiscock and Taylor claimed that
"in all physically realistic cases, macroscopic zero temperature black hole
solutions do not exist." We show this conclusion was reached on the basis of an
incorrect calculation.
| [
{
"created": "Tue, 14 Nov 2000 21:53:36 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Lowe",
"David A.",
""
]
] | In a recent paper (gr-qc/0002007), Anderson, Hiscock and Taylor claimed that "in all physically realistic cases, macroscopic zero temperature black hole solutions do not exist." We show this conclusion was reached on the basis of an incorrect calculation. |
1410.6580 | Hiroshi Kozaki | Hiroshi Kozaki, Tatsuhiko Koike and Hideki Ishihara | Membranes with a symmetry of cohomogeneity one | null | null | 10.1103/PhysRevD.91.025007 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the dynamics of the Nambu-Goto membranes with cohomogeneity one
symmetry, i.e., the membranes whose trajectories are foliated by homogeneous
surfaces. It is shown that the equation of motion reduces to a geodesic
equation on a certain manifold, which is constructed from the original
spacetime and Killing vector fields thereon. A general method is presented for
classifying the symmetry of cohomogeneity one membranes in a given spacetime.
The classification is completely carried out in Minkowski spacetime. We analyze
one of the obtained classes in depth and derive an exact solution.
| [
{
"created": "Fri, 24 Oct 2014 05:46:13 GMT",
"version": "v1"
},
{
"created": "Fri, 31 Oct 2014 04:55:08 GMT",
"version": "v2"
}
] | 2015-06-23 | [
[
"Kozaki",
"Hiroshi",
""
],
[
"Koike",
"Tatsuhiko",
""
],
[
"Ishihara",
"Hideki",
""
]
] | We study the dynamics of the Nambu-Goto membranes with cohomogeneity one symmetry, i.e., the membranes whose trajectories are foliated by homogeneous surfaces. It is shown that the equation of motion reduces to a geodesic equation on a certain manifold, which is constructed from the original spacetime and Killing vector fields thereon. A general method is presented for classifying the symmetry of cohomogeneity one membranes in a given spacetime. The classification is completely carried out in Minkowski spacetime. We analyze one of the obtained classes in depth and derive an exact solution. |
2306.04069 | De-Chang Dai | De-Chang Dai, Dejan Stojkovic | Superluminal propagation along the brane in space with extra dimensions | 6 pages, 8 figures, | Eur. Phys. J. C (2024) 84:175 | 10.1140/epjc/s10052-024-12535-w | null | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by/4.0/ | We demonstrate that a model with extra dimensions formulated in Csaki et al.
(Phys Rev D 62, 045015), which fatefully reproduces Friedmann-Robertson-Walker
(FRW) equations on the brane, allows for an apparent superluminal propagation
of massless signals. Namely, a massive brane curves the spacetime and affects
the trajectory of a signal in a way that allows a signal sent from the brane
through the bulk to arrive (upon returning) to a distant point on the brane
faster than the light can propagate along the brane. In particular, the signal
sent along the brane suffers a greater gravitational time delay than the bulk
signal due to the presence of matter on the brane. While the bulk signal never
moves with the speed greater than the speed of light in its own locality, this
effect still enables one to send signals faster than light from the brane
observer's perspective. For example, this effect might be used to resolve the
cosmological horizon problem. In addition, one of the striking observational
signatures would be arrival of the same gravitational wave signal at two
different times, where the first signals arrives before its electromagnetic
counterpart. We used GW170104 gravitational wave event to impose a strong limit
on the model with extra dimensions in question.
| [
{
"created": "Wed, 7 Jun 2023 00:02:50 GMT",
"version": "v1"
},
{
"created": "Thu, 22 Feb 2024 07:04:16 GMT",
"version": "v2"
}
] | 2024-02-23 | [
[
"Dai",
"De-Chang",
""
],
[
"Stojkovic",
"Dejan",
""
]
] | We demonstrate that a model with extra dimensions formulated in Csaki et al. (Phys Rev D 62, 045015), which fatefully reproduces Friedmann-Robertson-Walker (FRW) equations on the brane, allows for an apparent superluminal propagation of massless signals. Namely, a massive brane curves the spacetime and affects the trajectory of a signal in a way that allows a signal sent from the brane through the bulk to arrive (upon returning) to a distant point on the brane faster than the light can propagate along the brane. In particular, the signal sent along the brane suffers a greater gravitational time delay than the bulk signal due to the presence of matter on the brane. While the bulk signal never moves with the speed greater than the speed of light in its own locality, this effect still enables one to send signals faster than light from the brane observer's perspective. For example, this effect might be used to resolve the cosmological horizon problem. In addition, one of the striking observational signatures would be arrival of the same gravitational wave signal at two different times, where the first signals arrives before its electromagnetic counterpart. We used GW170104 gravitational wave event to impose a strong limit on the model with extra dimensions in question. |
gr-qc/0407009 | Akira Ohashi | Akira Ohashi and Masa-aki Sakagami | Massive quasi-normal mode | 12 pages, 10 figures, accepted for publication in Classical Quantum
Gravity | Class.Quant.Grav. 21 (2004) 3973-3984 | 10.1088/0264-9381/21/16/010 | null | gr-qc | null | This paper purposes to study quasi-normal modes due to massive scalar fields.
We, in particular, investigate the dependence of QNM frequencies on the field
mass. By this research, we find that there are quasi-normal modes with
arbitrarily long life when the field mass has special values. It is also found
that QNM can disappear when the field mass exceed these values.
| [
{
"created": "Fri, 2 Jul 2004 06:56:14 GMT",
"version": "v1"
}
] | 2009-11-10 | [
[
"Ohashi",
"Akira",
""
],
[
"Sakagami",
"Masa-aki",
""
]
] | This paper purposes to study quasi-normal modes due to massive scalar fields. We, in particular, investigate the dependence of QNM frequencies on the field mass. By this research, we find that there are quasi-normal modes with arbitrarily long life when the field mass has special values. It is also found that QNM can disappear when the field mass exceed these values. |
gr-qc/9902002 | Lior M. Burko | Lior M. Burko | Dipole perturbations of the Reissner-Nordstrom solution. II. The axial
case | Submitted to Phys. Rev. D | Phys.Rev. D59 (1999) 084003 | 10.1103/PhysRevD.59.084003 | null | gr-qc | null | We study the linear metric perturbations of the Reissner-Nordstr\"{o}m
solution for the case of axial perturbation modes. We find that the well-known
perturbative analysis fails for the case of dipole $(l=1)$ perturbations,
although valid for higher multipoles. We define new radial functions, with
which the perturbation formalism is generalized to all multipole orders,
including the dipole. We then complete the solution by constructing the
perturbed metric and Maxwell tensors.
| [
{
"created": "Mon, 1 Feb 1999 00:12:48 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Burko",
"Lior M.",
""
]
] | We study the linear metric perturbations of the Reissner-Nordstr\"{o}m solution for the case of axial perturbation modes. We find that the well-known perturbative analysis fails for the case of dipole $(l=1)$ perturbations, although valid for higher multipoles. We define new radial functions, with which the perturbation formalism is generalized to all multipole orders, including the dipole. We then complete the solution by constructing the perturbed metric and Maxwell tensors. |
1108.5224 | Tim Koslowski A | Tim Koslowski | Shape Dynamics | 4 pages LaTeX, no figures | J. Phys.: Conf. Ser. (2012) 360, 012059 | 10.1088/1742-6596/360/1/012059 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | General Relativity can be reformulated as a geometrodynamical theory, called
Shape Dynamics, that is not based on spacetime (in particular refoliation)
symmetry but on spatial diffeomorphism and local spatial conformal symmetry.
This leads to a constraint algebra that is (unlike General Relativity) a Lie
algebra, where all local constraints are linear in momenta and may thus be
quantized as vector fields on the geometrodynamic configuration space. The
Hamiltonian of Shape Dynamics is complicated but admits simple expressions
whenever spatial derivatives are negligible.
| [
{
"created": "Fri, 26 Aug 2011 01:33:42 GMT",
"version": "v1"
}
] | 2012-05-24 | [
[
"Koslowski",
"Tim",
""
]
] | General Relativity can be reformulated as a geometrodynamical theory, called Shape Dynamics, that is not based on spacetime (in particular refoliation) symmetry but on spatial diffeomorphism and local spatial conformal symmetry. This leads to a constraint algebra that is (unlike General Relativity) a Lie algebra, where all local constraints are linear in momenta and may thus be quantized as vector fields on the geometrodynamic configuration space. The Hamiltonian of Shape Dynamics is complicated but admits simple expressions whenever spatial derivatives are negligible. |
gr-qc/9806055 | Sanjay Jhingan | S. S. Deshingkar, S. Jhingan and P. S. Joshi | On the global visibility of singularity in quasi-spherical collapse | Latex file, 32 pages, 12 postscript figures. To appear in the Journal
of General Relativity and Gravitation | Gen.Rel.Grav. 30 (1998) 1477-1499 | 10.1023/A:1018813108516 | null | gr-qc | null | We analyze here the issue of local versus the global visibility of a
singularity that forms in gravitational collapse of a dust cloud, which has
important implications for the weak and strong versions of the cosmic
censorship hypothesis. We find conditions as to when a singularity will be only
locally naked, rather than being globally visible, thus preseving the weak
censorship hypothesis. The conditions for formation of a black hole or naked
singularity in the Szekeres quasi-spherical collapse models are worked out. The
causal behaviour of the singularity curve is studied by examining the outgoing
radial null geodesics, and the final outcome of collapse is related to the
nature of the regular initial data specified on an initial hypersurface from
which the collapse evolves. An interesting feature that emerges is the
singularity in Szekeres spacetimes can be ``directionally naked''.
| [
{
"created": "Thu, 11 Jun 1998 12:16:27 GMT",
"version": "v1"
}
] | 2015-06-25 | [
[
"Deshingkar",
"S. S.",
""
],
[
"Jhingan",
"S.",
""
],
[
"Joshi",
"P. S.",
""
]
] | We analyze here the issue of local versus the global visibility of a singularity that forms in gravitational collapse of a dust cloud, which has important implications for the weak and strong versions of the cosmic censorship hypothesis. We find conditions as to when a singularity will be only locally naked, rather than being globally visible, thus preseving the weak censorship hypothesis. The conditions for formation of a black hole or naked singularity in the Szekeres quasi-spherical collapse models are worked out. The causal behaviour of the singularity curve is studied by examining the outgoing radial null geodesics, and the final outcome of collapse is related to the nature of the regular initial data specified on an initial hypersurface from which the collapse evolves. An interesting feature that emerges is the singularity in Szekeres spacetimes can be ``directionally naked''. |
gr-qc/9804007 | Herbert Balasin | P.C. Aichelburg (University of Vienna), H. Balasin (TU-Wien) | ADM and Bondi four-momenta for the ultrarelativistic Schwarzschild black
hole | Changes in the expression used for the ADM four-momentum without
altering the result, correction of some minor typing errors | Class.Quant.Grav. 15 (1998) 3841-3844 | 10.1088/0264-9381/15/12/012 | UWThPh 1998-12, TUW 98/08 | gr-qc | null | We argue that it is possible to assign Bondi as well as ADM four-momentum to
the ultrarelativistic limit of the Schwarzschild black hole in agreement to
what is expected on physical grounds: The Bondi-momentum is lightlike and equal
to the ADM-momentum up to the retarded time when particle and radiation escape
to infinity and drops to zero thereafter, leaving flat space behind.
| [
{
"created": "Fri, 3 Apr 1998 09:21:48 GMT",
"version": "v1"
},
{
"created": "Fri, 10 Jul 1998 08:19:24 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Aichelburg",
"P. C.",
"",
"University of Vienna"
],
[
"Balasin",
"H.",
"",
"TU-Wien"
]
] | We argue that it is possible to assign Bondi as well as ADM four-momentum to the ultrarelativistic limit of the Schwarzschild black hole in agreement to what is expected on physical grounds: The Bondi-momentum is lightlike and equal to the ADM-momentum up to the retarded time when particle and radiation escape to infinity and drops to zero thereafter, leaving flat space behind. |
2201.01295 | Monika Pietrzyk Dr | Monika E. Pietrzyk and C\'ecile Barbachoux | On the Covariant Hamilton-Jacobi Equation for the Teleparallel
Equivalent of General Relativity | 11 pages | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The covariant Hamilton-Jacobi equation for the Teleparallel Equivalent of
General Relativity is derived based on the analysis of the second-class
constraints within the covariant Hamiltonian theory of De Donder-Weyl according
to the constraints algorithm developed by Kanatchikov.
| [
{
"created": "Tue, 4 Jan 2022 18:57:32 GMT",
"version": "v1"
}
] | 2022-01-05 | [
[
"Pietrzyk",
"Monika E.",
""
],
[
"Barbachoux",
"Cécile",
""
]
] | The covariant Hamilton-Jacobi equation for the Teleparallel Equivalent of General Relativity is derived based on the analysis of the second-class constraints within the covariant Hamiltonian theory of De Donder-Weyl according to the constraints algorithm developed by Kanatchikov. |
1905.03233 | Piero Nicolini | Marco Knipfer, Sven K\"oppel, Jonas Mureika, Piero Nicolini | Generalized Uncertainty Principle and Black Holes in Higher Dimensional
Self-Complete Gravity | 32 pages, 8 figures, 1 table, revised version in press on JCAP | JCAP 1908 (2019) no.08, 008 | 10.1088/1475-7516/2019/08/008 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we consider generalized uncertainty principle (GUP) effects in
higher dimensional black hole spacetimes via a nonlocal gravity approach. We
study three possible modifications of momentum space measure emerging from GUP,
including the original Kempf-Mangano-Mann (KMM) proposal. By following the KMM
model we derive a family of black hole spacetimes. The case of five spacetime
dimensions is a special one. We found an exact black hole solution with a
Barriola-Vilenkin monopole at the origin. This object turns out to be the end
point of the black hole evaporation. Interestingly for smaller masses, we found
a "naked monopole" rather than a generic naked singularity. We also show that
the Carr-Lake-Casadio-Scardigli proposal leads to mild modifications of
spacetime metrics with respect to the Schwarzschild-Tangherlini solution.
Finally, by demanding the same degree of convergence in the ultraviolet regime
for any spacetime dimension, we derive a family of black hole solutions that
fulfill the gravity self-completeness paradigm. The evaporation of such black
holes is characterized by a fluctuating luminosity, which we dub a lighthouse
effect.
| [
{
"created": "Wed, 8 May 2019 17:43:31 GMT",
"version": "v1"
},
{
"created": "Fri, 2 Aug 2019 10:56:44 GMT",
"version": "v2"
}
] | 2019-09-10 | [
[
"Knipfer",
"Marco",
""
],
[
"Köppel",
"Sven",
""
],
[
"Mureika",
"Jonas",
""
],
[
"Nicolini",
"Piero",
""
]
] | In this paper we consider generalized uncertainty principle (GUP) effects in higher dimensional black hole spacetimes via a nonlocal gravity approach. We study three possible modifications of momentum space measure emerging from GUP, including the original Kempf-Mangano-Mann (KMM) proposal. By following the KMM model we derive a family of black hole spacetimes. The case of five spacetime dimensions is a special one. We found an exact black hole solution with a Barriola-Vilenkin monopole at the origin. This object turns out to be the end point of the black hole evaporation. Interestingly for smaller masses, we found a "naked monopole" rather than a generic naked singularity. We also show that the Carr-Lake-Casadio-Scardigli proposal leads to mild modifications of spacetime metrics with respect to the Schwarzschild-Tangherlini solution. Finally, by demanding the same degree of convergence in the ultraviolet regime for any spacetime dimension, we derive a family of black hole solutions that fulfill the gravity self-completeness paradigm. The evaporation of such black holes is characterized by a fluctuating luminosity, which we dub a lighthouse effect. |
1711.07290 | Sunny Vagnozzi | Jibitesh Dutta, Wompherdeiki Khyllep, Emmanuel N. Saridakis, Nicola
Tamanini, Sunny Vagnozzi | Cosmological dynamics of mimetic gravity | 30 pages, 7 figures. Final version published in JCAP | JCAP 1802 (2018) 041 | 10.1088/1475-7516/2018/02/041 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a detailed investigation of the dynamical behavior of mimetic
gravity with a general potential for the mimetic scalar field. Performing a
phase-space and stability analysis, we show that the scenario at hand can
successfully describe the thermal history of the universe, namely the
successive sequence of radiation, matter, and dark-energy eras. Additionally,
at late times the universe can either approach a de Sitter solution, or a
scaling accelerated attractor where the dark-matter and dark-energy density
parameters are of the same order, thus offering an alleviation of the cosmic
coincidence problem. Applying our general analysis to various specific
potential choices, including the power-law and the exponential ones, we show
that mimetic gravity can be brought into good agreement with the observed
behavior of the universe. Moreover, with an inverse square potential we find
that mimetic gravity offers an appealing unified cosmological scenario where
both dark energy and dark matter are characterized by a single scalar field,
and where the cosmic coincidence problem is alleviated.
| [
{
"created": "Mon, 20 Nov 2017 12:50:05 GMT",
"version": "v1"
},
{
"created": "Wed, 21 Feb 2018 10:16:08 GMT",
"version": "v2"
}
] | 2018-12-13 | [
[
"Dutta",
"Jibitesh",
""
],
[
"Khyllep",
"Wompherdeiki",
""
],
[
"Saridakis",
"Emmanuel N.",
""
],
[
"Tamanini",
"Nicola",
""
],
[
"Vagnozzi",
"Sunny",
""
]
] | We present a detailed investigation of the dynamical behavior of mimetic gravity with a general potential for the mimetic scalar field. Performing a phase-space and stability analysis, we show that the scenario at hand can successfully describe the thermal history of the universe, namely the successive sequence of radiation, matter, and dark-energy eras. Additionally, at late times the universe can either approach a de Sitter solution, or a scaling accelerated attractor where the dark-matter and dark-energy density parameters are of the same order, thus offering an alleviation of the cosmic coincidence problem. Applying our general analysis to various specific potential choices, including the power-law and the exponential ones, we show that mimetic gravity can be brought into good agreement with the observed behavior of the universe. Moreover, with an inverse square potential we find that mimetic gravity offers an appealing unified cosmological scenario where both dark energy and dark matter are characterized by a single scalar field, and where the cosmic coincidence problem is alleviated. |
2112.07388 | Oliver Sch\"on | Oliver Sch\"on, Daniela D. Doneva | Tensor-Multi-Scalar Gravity: Equations of Motion to 2.5 post-Newtonian
Order | 34 pages, close to published version | Physical Review D (Vol. 105, No. 6, 2022) | 10.1103/PhysRevD.105.064034 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the present paper we take a step towards the generalization of the
post-Newtonian formalism to tensor-multi-scalar theories. These are theories
where we have more than one scalar field being mediators of the gravitational
interaction in addition to the spacetime metric. They are very natural
extensions of Einstein's gravity allowing for the existence of new classes of
compact objects and offering interesting phenomenology reaching far beyond the
single scalar field theories. We calculate the expansion up to 2.5
post-Newtonian order in the near zone using the so-called direct integration of
the relaxed Einstein equations formalism and derive the equation of motion.
This work is the first step towards the calculation of gravitational waveforms
in tensor-multi-scalar theories.
| [
{
"created": "Tue, 14 Dec 2021 13:28:54 GMT",
"version": "v1"
},
{
"created": "Mon, 20 Dec 2021 14:58:26 GMT",
"version": "v2"
},
{
"created": "Wed, 23 Mar 2022 13:43:16 GMT",
"version": "v3"
}
] | 2022-03-24 | [
[
"Schön",
"Oliver",
""
],
[
"Doneva",
"Daniela D.",
""
]
] | In the present paper we take a step towards the generalization of the post-Newtonian formalism to tensor-multi-scalar theories. These are theories where we have more than one scalar field being mediators of the gravitational interaction in addition to the spacetime metric. They are very natural extensions of Einstein's gravity allowing for the existence of new classes of compact objects and offering interesting phenomenology reaching far beyond the single scalar field theories. We calculate the expansion up to 2.5 post-Newtonian order in the near zone using the so-called direct integration of the relaxed Einstein equations formalism and derive the equation of motion. This work is the first step towards the calculation of gravitational waveforms in tensor-multi-scalar theories. |
gr-qc/0703089 | Ralf Lehnert | Ralf Lehnert | Quantum-gravity phenomenology, Lorentz symmetry, and the SME | 8 pages, 2 figures, Plenary talk at 12th Mexican School on Particles
and Fields and 6th Latin American Symposium on High Energy Physics
(VI-Silafae/XII-MSPF), Puerto Vallarta, Mexico, 1-8 Nov 2006 | AIPConf.Proc.917:138-145,2007 | 10.1063/1.2751950 | MIT-CPT-3822 | gr-qc | null | Violations of spacetime symmetries have recently been identified as promising
signatures for physics underlying the Standard Model. The present talk gives an
overview over various topics in this field: The motivations for
spacetime-symmetry research, including some mechanisms for Lorentz breaking,
are reviewed. An effective field theory called the Standard-Model Extension
(SME) for the description of the resulting low-energy effects is introduced,
and some experimental tests of Lorentz and CPT invariance are listed.
| [
{
"created": "Fri, 16 Mar 2007 21:41:12 GMT",
"version": "v1"
}
] | 2008-11-26 | [
[
"Lehnert",
"Ralf",
""
]
] | Violations of spacetime symmetries have recently been identified as promising signatures for physics underlying the Standard Model. The present talk gives an overview over various topics in this field: The motivations for spacetime-symmetry research, including some mechanisms for Lorentz breaking, are reviewed. An effective field theory called the Standard-Model Extension (SME) for the description of the resulting low-energy effects is introduced, and some experimental tests of Lorentz and CPT invariance are listed. |
1805.10810 | Sergey Yu. Vernov | E. Elizalde, S.D. Odintsov, E.O. Pozdeeva, S.Yu. Vernov | De Sitter and Power-law Solutions in Non-local Gauss-Bonnet Gravity | 15 pages, v2: accepted for publication in International Journal of
Geometric Methods in Modern Physics, references added | Int. J. Geom. Meth. Mod. Phys. 15 (2018) 1850188 | 10.1142/S0219887818501888 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The cosmological dynamics of a non-locally corrected gravity theory,
involving a power of the inverse d'Alembertian, is investigated. Casting the
dynamical equations into local form, the fixed points of the models are
derived, as well as corresponding de Sitter and power-law solutions. Necessary
and sufficient conditions on the model parameters for the existence of de
Sitter solutions are obtained. The possible existence of power-law solutions is
investigated, and it is proven that models with de Sitter solutions have no
power-law solutions. A model is found, which allows to describe the
matter-dominated phase of the Universe evolution.
| [
{
"created": "Mon, 28 May 2018 08:27:15 GMT",
"version": "v1"
},
{
"created": "Thu, 9 Aug 2018 11:47:06 GMT",
"version": "v2"
}
] | 2018-11-06 | [
[
"Elizalde",
"E.",
""
],
[
"Odintsov",
"S. D.",
""
],
[
"Pozdeeva",
"E. O.",
""
],
[
"Vernov",
"S. Yu.",
""
]
] | The cosmological dynamics of a non-locally corrected gravity theory, involving a power of the inverse d'Alembertian, is investigated. Casting the dynamical equations into local form, the fixed points of the models are derived, as well as corresponding de Sitter and power-law solutions. Necessary and sufficient conditions on the model parameters for the existence of de Sitter solutions are obtained. The possible existence of power-law solutions is investigated, and it is proven that models with de Sitter solutions have no power-law solutions. A model is found, which allows to describe the matter-dominated phase of the Universe evolution. |
gr-qc/9510013 | David Hartley | David Hartley, (GMD - German National Research Center for Information
Technology, St. Augustin, Germany) | Normal frames for non-Riemannian connections | 4 pages, plain TeX. To appear in Class. Quantum Grav | Class.Quant.Grav.12:L103-L106,1995 | 10.1088/0264-9381/12/11/001 | null | gr-qc | null | The principal properties of geodesic normal coordinates are the vanishing of
the connection components and first derivatives of the metric components at
some point. It is well-known that these hold only at points where the
connection has vanishing torsion and non-metricity. However, it is shown that
normal frames, possessing the essential features of normal coordinates, can
still be constructed when the connection is non-Riemannian.
| [
{
"created": "Mon, 9 Oct 1995 09:42:02 GMT",
"version": "v1"
}
] | 2010-04-06 | [
[
"Hartley",
"David",
""
]
] | The principal properties of geodesic normal coordinates are the vanishing of the connection components and first derivatives of the metric components at some point. It is well-known that these hold only at points where the connection has vanishing torsion and non-metricity. However, it is shown that normal frames, possessing the essential features of normal coordinates, can still be constructed when the connection is non-Riemannian. |
2402.14913 | Ra\'ul Carballo-Rubio | Ra\'ul Carballo-Rubio, Francesco Di Filippo, Stefano Liberati and Matt
Visser | Mass inflation without Cauchy horizons | 6 pages, 3 figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Mass inflation is a well established instability, conventionally associated
to Cauchy horizons (which are also inner trapping horizons) of stationary
geometries, leading to a divergent exponential buildup of energy. We show here
that finite (but often large) exponential buildups of energy are generically
present for dynamical geometries endowed with slowly-evolving inner trapping
horizons, even in the absence of Cauchy horizons. This provides a more general
definition of mass inflation based on quasi-local concepts. We also show that
various known results in the literature are recovered in the limit in which the
inner trapping horizon asymptotically approaches a Cauchy horizon. Our results
imply that black hole geometries with non-extremal inner horizons, including
the Kerr geometry in general relativity, and non-extremal regular black holes
in theories beyond general relativity, can describe dynamical transients but
not the long-lived endpoint of gravitational collapse.
| [
{
"created": "Thu, 22 Feb 2024 19:00:01 GMT",
"version": "v1"
}
] | 2024-02-26 | [
[
"Carballo-Rubio",
"Raúl",
""
],
[
"Di Filippo",
"Francesco",
""
],
[
"Liberati",
"Stefano",
""
],
[
"Visser",
"Matt",
""
]
] | Mass inflation is a well established instability, conventionally associated to Cauchy horizons (which are also inner trapping horizons) of stationary geometries, leading to a divergent exponential buildup of energy. We show here that finite (but often large) exponential buildups of energy are generically present for dynamical geometries endowed with slowly-evolving inner trapping horizons, even in the absence of Cauchy horizons. This provides a more general definition of mass inflation based on quasi-local concepts. We also show that various known results in the literature are recovered in the limit in which the inner trapping horizon asymptotically approaches a Cauchy horizon. Our results imply that black hole geometries with non-extremal inner horizons, including the Kerr geometry in general relativity, and non-extremal regular black holes in theories beyond general relativity, can describe dynamical transients but not the long-lived endpoint of gravitational collapse. |
1507.03093 | Milovan Vasilic | Milovan Vasili\'c | Geometric sigma model of the Universe | 31 pages, 9 figures | Chinese Physics C Vol. 41, No. 5 (2017) 055102 | 10.1088/1674-1137/41/5/055102 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The purpose of this work is to demonstrate how an arbitrarily chosen
background of the Universe can be made a solution of a simple geometric sigma
model. Geometric sigma models are purely geometric theories in which spacetime
coordinates are seen as scalar fields coupled to gravity. Although they look
like ordinary sigma models, they have the peculiarity that their complete
matter content can be gauged away. The remaining geometric theory possesses a
background solution that is predefined in the process of constructing the
theory. The fact that background configuration is specified in advance is
another peculiarity of geometric sigma models. In this paper, I construct
geometric sigma models based on different background geometries of the
Universe. Whatever background geometry is chosen, the dynamics of its small
perturbations is shown to posses a generic classical stability. This way, any
freely chosen background metric is made a stable solution of a simple model.
Three particular models of the Universe are considered as examples of how this
is done in practice.
| [
{
"created": "Sat, 11 Jul 2015 10:57:25 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Jul 2016 15:20:50 GMT",
"version": "v2"
},
{
"created": "Sat, 26 Nov 2016 12:32:58 GMT",
"version": "v3"
},
{
"created": "Mon, 23 Jan 2017 12:18:26 GMT",
"version": "v4"
},
{
"created": "Sat, 18 Feb 2017 22:12:29 GMT",
"version": "v5"
},
{
"created": "Fri, 31 Mar 2017 14:02:07 GMT",
"version": "v6"
}
] | 2017-04-03 | [
[
"Vasilić",
"Milovan",
""
]
] | The purpose of this work is to demonstrate how an arbitrarily chosen background of the Universe can be made a solution of a simple geometric sigma model. Geometric sigma models are purely geometric theories in which spacetime coordinates are seen as scalar fields coupled to gravity. Although they look like ordinary sigma models, they have the peculiarity that their complete matter content can be gauged away. The remaining geometric theory possesses a background solution that is predefined in the process of constructing the theory. The fact that background configuration is specified in advance is another peculiarity of geometric sigma models. In this paper, I construct geometric sigma models based on different background geometries of the Universe. Whatever background geometry is chosen, the dynamics of its small perturbations is shown to posses a generic classical stability. This way, any freely chosen background metric is made a stable solution of a simple model. Three particular models of the Universe are considered as examples of how this is done in practice. |
1206.5976 | Sergey Cherkas L | S. L. Cherkas and V. L. Kalashnikov | Can the scale factor be rippled? | 10 pages, 5 figures | Nonlinear Phenomena in Complex Systems 15 (2012) 253-263 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We address an issue: would the cosmological scale factor be a locally
oscillating quantity? This problem is examined in the framework of two
classical 1+1-dimensional models: the first one is a string against a curved
background, and the second one is an inhomogeneous Bianchi I model. For the
string model, it is shown that there exist the gauge and the initial condition
providing an oscillation of scale factor against a slowly evolving background,
which is not affected by such an oscillation "at the mean". For the
inhomogeneous Bianchi I model with the conformal time gauge, an initially
homogeneous scale factor can become inhomogeneous and undergo the nonlinear
oscillations. As is shown these nonlinear oscillations can be treated as a
nonlinear gauge wave.
| [
{
"created": "Tue, 26 Jun 2012 12:56:27 GMT",
"version": "v1"
},
{
"created": "Wed, 18 Jul 2012 07:45:35 GMT",
"version": "v2"
}
] | 2015-04-24 | [
[
"Cherkas",
"S. L.",
""
],
[
"Kalashnikov",
"V. L.",
""
]
] | We address an issue: would the cosmological scale factor be a locally oscillating quantity? This problem is examined in the framework of two classical 1+1-dimensional models: the first one is a string against a curved background, and the second one is an inhomogeneous Bianchi I model. For the string model, it is shown that there exist the gauge and the initial condition providing an oscillation of scale factor against a slowly evolving background, which is not affected by such an oscillation "at the mean". For the inhomogeneous Bianchi I model with the conformal time gauge, an initially homogeneous scale factor can become inhomogeneous and undergo the nonlinear oscillations. As is shown these nonlinear oscillations can be treated as a nonlinear gauge wave. |
2203.13937 | Ajit Mehta | Ajit Kumar Mehta, Alessandra Buonanno, Roberto Cotesta, Abhirup Ghosh,
Noah Sennett, Jan Steinhoff | Tests of General Relativity with Gravitational-Wave Observations using a
Flexible--Theory-Independent Method | 24 pages, 13 figures | Phys. Rev. D 107, 044020 (2023) | 10.1103/PhysRevD.107.044020 | LIGO-P2200083-v2 | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We perform tests of General Relativity (GR) with gravitational waves (GWs)
from the inspiral stage of compact binaries using a theory-independent
framework, which adds generic phase corrections to each multipole of a GR
waveform model in frequency domain. This method has been demonstrated on
LIGO-Virgo observations to provide stringent constraints on post-Newtonian
predictions of the inspiral and to assess systematic biases that may arise in
such parameterized tests. Here, we detail the anatomy of our framework for
aligned-spin waveform models. We explore the effects of higher modes in the
underlying signal on tests of GR through analyses of two unequal-mass,
simulated binary signals similar to GW190412 and GW190814. We show that the
inclusion of higher modes improves both the precision and the accuracy of the
measurement of the deviation parameters. Our testing framework also allows us
to vary the underlying baseline GR waveform model and the frequency at which
the non-GR inspiral corrections are tapered off. We find that to optimize the
GR test of high-mass binaries, comprehensive studies would need to be done to
determine the best choice of the tapering frequency as a function of the
binary's properties. We also carry out an analysis on the binary neutron-star
event GW170817 to set bounds on the coupling constant $\alpha_0$ of
Jordan-Fierz-Brans-Dicke gravity. We take two plausible approaches; in the
first \emph{theory-agnostic} approach we find a bound $\alpha_0 \lesssim
2\times 10^{-1}$ from measuring the dipole-radiation for different neutron-star
equations of state, while in the second \emph{theory-specific} approach we
obtain $\alpha_0 \lesssim 4\times 10^{-1}$, both at $68\%$ credible level.
These differences arise mainly due to different statistical hypotheses used for
the analysis.
| [
{
"created": "Fri, 25 Mar 2022 23:37:32 GMT",
"version": "v1"
}
] | 2023-04-05 | [
[
"Mehta",
"Ajit Kumar",
""
],
[
"Buonanno",
"Alessandra",
""
],
[
"Cotesta",
"Roberto",
""
],
[
"Ghosh",
"Abhirup",
""
],
[
"Sennett",
"Noah",
""
],
[
"Steinhoff",
"Jan",
""
]
] | We perform tests of General Relativity (GR) with gravitational waves (GWs) from the inspiral stage of compact binaries using a theory-independent framework, which adds generic phase corrections to each multipole of a GR waveform model in frequency domain. This method has been demonstrated on LIGO-Virgo observations to provide stringent constraints on post-Newtonian predictions of the inspiral and to assess systematic biases that may arise in such parameterized tests. Here, we detail the anatomy of our framework for aligned-spin waveform models. We explore the effects of higher modes in the underlying signal on tests of GR through analyses of two unequal-mass, simulated binary signals similar to GW190412 and GW190814. We show that the inclusion of higher modes improves both the precision and the accuracy of the measurement of the deviation parameters. Our testing framework also allows us to vary the underlying baseline GR waveform model and the frequency at which the non-GR inspiral corrections are tapered off. We find that to optimize the GR test of high-mass binaries, comprehensive studies would need to be done to determine the best choice of the tapering frequency as a function of the binary's properties. We also carry out an analysis on the binary neutron-star event GW170817 to set bounds on the coupling constant $\alpha_0$ of Jordan-Fierz-Brans-Dicke gravity. We take two plausible approaches; in the first \emph{theory-agnostic} approach we find a bound $\alpha_0 \lesssim 2\times 10^{-1}$ from measuring the dipole-radiation for different neutron-star equations of state, while in the second \emph{theory-specific} approach we obtain $\alpha_0 \lesssim 4\times 10^{-1}$, both at $68\%$ credible level. These differences arise mainly due to different statistical hypotheses used for the analysis. |
1407.3401 | Saulo Pereira H | A. Pinho S. S., S. H. Pereira and J. F. Jesus | A new approach on the stability analysis in ELKO cosmology | 16 pages, some new comments in the Introduction and at the begining
of Section II | Eur. Phys. J. C (2015) 75:36 | 10.1140/epjc/s10052-015-3260-9 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work it has been developed a new approach to study the stability of a
system composed by an ELKO field interacting with dark matter, which could give
some contribution in order to alleviate the cosmic coincidence problem. It is
assumed that the potential which characterizes the ELKO field is not specified,
but it is related to a constant parameter $\delta$. The strength of the
interaction between matter and ELKO field is characterized by a constant
parameter $\beta$ and it is also assumed that both ELKO field as matter energy
density are related to their pressures by equations of state parameters
$\omega_\phi$ and $\omega_m$, respectively. The system of equations is analysed
by a dynamical system approach. It has been found the conditions of stability
between the parameters $\delta$ and $\beta$ in order to have stable fixed
points for the system for different values of the equation of state parameters
$\omega_\phi$ and $\omega_m$, and the results are presented in form of tables.
The possibility of decay of ELKO field into dark matter or vice versa can be
read directly from the tables, since the parameters $\delta$ and $\beta$
satisfy some inequalities. It allows us to constrain the potential assuming
that we have a stable system for different interactions terms between the ELKO
field and dark matter. The cosmic coincidence problem can be alleviated for
some specific relations between the parameters of the model.
| [
{
"created": "Sat, 12 Jul 2014 17:29:06 GMT",
"version": "v1"
},
{
"created": "Mon, 5 Jan 2015 19:19:24 GMT",
"version": "v2"
}
] | 2015-02-04 | [
[
"S.",
"A. Pinho S.",
""
],
[
"Pereira",
"S. H.",
""
],
[
"Jesus",
"J. F.",
""
]
] | In this work it has been developed a new approach to study the stability of a system composed by an ELKO field interacting with dark matter, which could give some contribution in order to alleviate the cosmic coincidence problem. It is assumed that the potential which characterizes the ELKO field is not specified, but it is related to a constant parameter $\delta$. The strength of the interaction between matter and ELKO field is characterized by a constant parameter $\beta$ and it is also assumed that both ELKO field as matter energy density are related to their pressures by equations of state parameters $\omega_\phi$ and $\omega_m$, respectively. The system of equations is analysed by a dynamical system approach. It has been found the conditions of stability between the parameters $\delta$ and $\beta$ in order to have stable fixed points for the system for different values of the equation of state parameters $\omega_\phi$ and $\omega_m$, and the results are presented in form of tables. The possibility of decay of ELKO field into dark matter or vice versa can be read directly from the tables, since the parameters $\delta$ and $\beta$ satisfy some inequalities. It allows us to constrain the potential assuming that we have a stable system for different interactions terms between the ELKO field and dark matter. The cosmic coincidence problem can be alleviated for some specific relations between the parameters of the model. |
2407.15753 | Askold Vilkha | Askold Vilkha (1), Anjali Yelikar (1), Richard O'Shaughnessy (1),
Jocelyn Read (2) ((1) Center for Computational Relativity and Gravitation
Rochester Institute of Technology, (2) Nicholas and Lee Begovich Center for
Gravitational-Wave Physics and Astronomy California State University
Fullerton) | Inference on neutron star parameters and the nuclear equation of state
with RIFT, using prior EOS information | null | null | null | LIGO DCC 2400278 | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we present an inference method for determining neutron star
parameters and constraining the nuclear equation of state (EOS) using the RIFT
parameter inference engine. We incorporate externally-produced prior
information about the EOS to improve the accuracy and efficiency of the
inference process. We apply this method to the GW170817 event and assess its
performance. Our results demonstrate the effectiveness of incorporating prior
EOS information in the inference process, leading to sharper conclusions and
more rapid inference on new detections. This approach has the potential to
enhance our understanding of neutron stars and the nuclear EOS in future
gravitational wave observations.
| [
{
"created": "Mon, 22 Jul 2024 15:58:57 GMT",
"version": "v1"
}
] | 2024-07-23 | [
[
"Vilkha",
"Askold",
""
],
[
"Yelikar",
"Anjali",
""
],
[
"O'Shaughnessy",
"Richard",
""
],
[
"Read",
"Jocelyn",
""
]
] | In this paper, we present an inference method for determining neutron star parameters and constraining the nuclear equation of state (EOS) using the RIFT parameter inference engine. We incorporate externally-produced prior information about the EOS to improve the accuracy and efficiency of the inference process. We apply this method to the GW170817 event and assess its performance. Our results demonstrate the effectiveness of incorporating prior EOS information in the inference process, leading to sharper conclusions and more rapid inference on new detections. This approach has the potential to enhance our understanding of neutron stars and the nuclear EOS in future gravitational wave observations. |
0812.1666 | Suman Ghosh | Suman Ghosh and Sayan Kar | Bulk spacetimes for cosmological braneworlds with a time--dependent
extra dimension | 31 pages, 10 figures, to appear in P.R.D | Phys.Rev.D80:064024,2009 | 10.1103/PhysRevD.80.064024 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We explore the possibilities of constructing bulk spacetimes in five
dimensions for warped braneworld models with a spatially flat
Friedmann-Robertson-Walker (FRW) line element on the 3-brane and with a
time-dependent extra dimension. Our first step in this direction involves
looking at the status of energy conditions when such a bulk line element is
assumed. We check these conditions by analysing the relevant inequalities, for
specific functional forms (chosen to satisfy certain desirable features) of the
warp factor, the cosmological scale factor and the extra-dimensional scale
factor. Subsequently, we aim at obtaining solutions with different types of
bulk matter sources. We begin with a general analysis of the solution space of
non-singular Randall-Sundrum type bulk models with an exponential warp factor
and a chosen equation of state. Thereafter, we focus on three specific bulk
sources -- the ordinary scalar field, the Brans-Dicke scalar and the dilaton.
In each case, we are able to solve the field equations and obtain desirable
solutions for which, we once again check the viability of the energy
conditions. We also show how one can place branes in the bulk using the
junction conditions. The issue of resolution of the bulk singularities which
appear in our solutions, using standard methods, is also presented briefly. In
summary, we are able to demonstrate, that it is indeed possible to construct
viable bulk spacetimes for warped cosmological braneworlds with a time-varying
extra dimension and with bulk matter satisfying the energy conditions.
| [
{
"created": "Tue, 9 Dec 2008 11:06:48 GMT",
"version": "v1"
},
{
"created": "Mon, 26 Jan 2009 09:03:48 GMT",
"version": "v2"
},
{
"created": "Tue, 31 Mar 2009 09:50:59 GMT",
"version": "v3"
},
{
"created": "Mon, 24 Aug 2009 08:06:43 GMT",
"version": "v4"
}
] | 2009-11-06 | [
[
"Ghosh",
"Suman",
""
],
[
"Kar",
"Sayan",
""
]
] | We explore the possibilities of constructing bulk spacetimes in five dimensions for warped braneworld models with a spatially flat Friedmann-Robertson-Walker (FRW) line element on the 3-brane and with a time-dependent extra dimension. Our first step in this direction involves looking at the status of energy conditions when such a bulk line element is assumed. We check these conditions by analysing the relevant inequalities, for specific functional forms (chosen to satisfy certain desirable features) of the warp factor, the cosmological scale factor and the extra-dimensional scale factor. Subsequently, we aim at obtaining solutions with different types of bulk matter sources. We begin with a general analysis of the solution space of non-singular Randall-Sundrum type bulk models with an exponential warp factor and a chosen equation of state. Thereafter, we focus on three specific bulk sources -- the ordinary scalar field, the Brans-Dicke scalar and the dilaton. In each case, we are able to solve the field equations and obtain desirable solutions for which, we once again check the viability of the energy conditions. We also show how one can place branes in the bulk using the junction conditions. The issue of resolution of the bulk singularities which appear in our solutions, using standard methods, is also presented briefly. In summary, we are able to demonstrate, that it is indeed possible to construct viable bulk spacetimes for warped cosmological braneworlds with a time-varying extra dimension and with bulk matter satisfying the energy conditions. |
gr-qc/9708037 | Eric Poisson | Stephen W. Leonard and Eric Poisson | Gravitational waves from binary systems in circular orbits: Convergence
of a dressed multipole truncation | 9 pages, ReVTeX, 1 postscript figure | Class.Quant.Grav. 15 (1998) 2075-2081 | 10.1088/0264-9381/15/8/002 | null | gr-qc | null | The gravitational radiation originating from a compact binary system in
circular orbit is usually expressed as an infinite sum over radiative multipole
moments. In a slow-motion approximation, each multipole moment is then
expressed as a post-Newtonian expansion in powers of v/c, the ratio of the
orbital velocity to the speed of light. The bare multipole truncation of the
radiation consists in keeping only the leading-order term in the post-Newtonian
expansion of each moment, but summing over all the multipole moments. In the
case of binary systems with small mass ratios, the bare multipole series was
shown in a previous paper to converge for all values v/c < 2/e, where e is the
base of natural logarithms. In this paper, we extend the analysis to a dressed
multipole truncation of the radiation, in which the leading-order moments are
corrected with terms of relative order (v/c)^2 and (v/c)^3. We find that the
dressed multipole series converges also for all values v/c < 2/e, and that it
coincides (within 1%) with the numerically ``exact'' results for v/c < 0.2.
| [
{
"created": "Sun, 17 Aug 1997 20:52:55 GMT",
"version": "v1"
}
] | 2009-10-30 | [
[
"Leonard",
"Stephen W.",
""
],
[
"Poisson",
"Eric",
""
]
] | The gravitational radiation originating from a compact binary system in circular orbit is usually expressed as an infinite sum over radiative multipole moments. In a slow-motion approximation, each multipole moment is then expressed as a post-Newtonian expansion in powers of v/c, the ratio of the orbital velocity to the speed of light. The bare multipole truncation of the radiation consists in keeping only the leading-order term in the post-Newtonian expansion of each moment, but summing over all the multipole moments. In the case of binary systems with small mass ratios, the bare multipole series was shown in a previous paper to converge for all values v/c < 2/e, where e is the base of natural logarithms. In this paper, we extend the analysis to a dressed multipole truncation of the radiation, in which the leading-order moments are corrected with terms of relative order (v/c)^2 and (v/c)^3. We find that the dressed multipole series converges also for all values v/c < 2/e, and that it coincides (within 1%) with the numerically ``exact'' results for v/c < 0.2. |
gr-qc/0508060 | Peter Kuhfittig K.F. | Peter K.F. Kuhfittig | Wormholes supported by small amounts of exotic matter: some corrections | 6 pages AMSTeX | null | null | null | gr-qc | null | It was pointed out by Fewster and Roman that some of the wormhole models
discussed by Kuhfittig suffer from the failure to distinguish proper from
coordinate distances. One of the advantages of "designer wormholes" is that
models can be altered. The purpose of this note is to show that by adjusting
the metric coefficients, some of these problems can be corrected. By doing so,
the basic idea can be retained: wormholes containing only small amounts of
exotic matter can still be traversable.
| [
{
"created": "Mon, 15 Aug 2005 18:01:53 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Kuhfittig",
"Peter K. F.",
""
]
] | It was pointed out by Fewster and Roman that some of the wormhole models discussed by Kuhfittig suffer from the failure to distinguish proper from coordinate distances. One of the advantages of "designer wormholes" is that models can be altered. The purpose of this note is to show that by adjusting the metric coefficients, some of these problems can be corrected. By doing so, the basic idea can be retained: wormholes containing only small amounts of exotic matter can still be traversable. |
2101.01203 | Paul Rodgers Mr | Oscar J. C. Dias, Ramon Masachs, Paul Rodgers | Boson stars and solitons confined in a Minkowski box | 35 pages; 17 figures. v2: Added right panel of Fig. 2 with details of
secondary soliton family and associated discussion | null | 10.1007/JHEP04(2021)236 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the static charged black hole bomb system, originally designed
for a (uncharged) rotating superradiant system by Press and Teukolsky. A
charged scalar field confined in a Minkowski cavity with a Maxwell gauge field
has a quantized spectrum of normal modes that can fit inside the box.
Back-reacting non-linearly these normal modes, we find the hairy solitons,
a.k.a boson stars (depending on the chosen $U(1)$ gauge), of the theory. The
scalar condensate is totally confined inside the box and, outside it, we have
the Reissner-Nordstr\"om solution. The Israel junction conditions at the box
surface layer determine the stress tensor that the box must have to confine the
scalar hair. Some of these horizonless hairy solutions exist for any value of
the scalar field charge and not only above the natural critical charges of the
theory (namely, the critical charges for the onset of the near-horizon and
superradiant instabilities of the Reissner-Nordstr\"om black hole). However,
the ground state solutions have a non-trivial intricate phase diagram with a
main and a secondary family of solitons (some with a Chandrasekhar mass limit
but others without) and there are a third and a fourth critical scalar field
charges where the soliton spectra changes radically. Most of these intricate
properties are not captured by a higher order perturbative analysis of the
problem where we simply back-react a normal mode of the system.
| [
{
"created": "Mon, 4 Jan 2021 19:08:31 GMT",
"version": "v1"
},
{
"created": "Thu, 11 Feb 2021 09:19:20 GMT",
"version": "v2"
}
] | 2021-05-12 | [
[
"Dias",
"Oscar J. C.",
""
],
[
"Masachs",
"Ramon",
""
],
[
"Rodgers",
"Paul",
""
]
] | We consider the static charged black hole bomb system, originally designed for a (uncharged) rotating superradiant system by Press and Teukolsky. A charged scalar field confined in a Minkowski cavity with a Maxwell gauge field has a quantized spectrum of normal modes that can fit inside the box. Back-reacting non-linearly these normal modes, we find the hairy solitons, a.k.a boson stars (depending on the chosen $U(1)$ gauge), of the theory. The scalar condensate is totally confined inside the box and, outside it, we have the Reissner-Nordstr\"om solution. The Israel junction conditions at the box surface layer determine the stress tensor that the box must have to confine the scalar hair. Some of these horizonless hairy solutions exist for any value of the scalar field charge and not only above the natural critical charges of the theory (namely, the critical charges for the onset of the near-horizon and superradiant instabilities of the Reissner-Nordstr\"om black hole). However, the ground state solutions have a non-trivial intricate phase diagram with a main and a secondary family of solitons (some with a Chandrasekhar mass limit but others without) and there are a third and a fourth critical scalar field charges where the soliton spectra changes radically. Most of these intricate properties are not captured by a higher order perturbative analysis of the problem where we simply back-react a normal mode of the system. |
1804.01893 | Martin Lesourd Mr | Martin Lesourd | A new singularity theorem for black holes which allows chronology
violation in the interior | Classical.Quantum.Gravity, accepted.
http://iopscience.iop.org/article/10.1088/1361-6382/aae75c | null | 10.1088/1361-6382/aae75c | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The interior of the Kerr solution is singular and achronological. The classic
singularity theorem by Hawking and Penrose relies on chronology, and thus does
not apply to the Kerr solution. An improvement of their theorem by Kriele
partially removes the requirement of chronology. However, both of these
singularity theorems fail to give any information on the type or location of
the incomplete geodesics. Here, using recent results of Minguzzi, we prove a
new singularity theorem, specifically designed to apply to black holes, which
enables locating null incomplete geodesics within the black hole interior, all
the while allowing certain forms of chronology violation in the interior.
| [
{
"created": "Thu, 5 Apr 2018 15:02:24 GMT",
"version": "v1"
},
{
"created": "Thu, 10 May 2018 19:27:15 GMT",
"version": "v2"
},
{
"created": "Thu, 16 Aug 2018 09:18:16 GMT",
"version": "v3"
},
{
"created": "Wed, 22 Aug 2018 10:15:15 GMT",
"version": "v4"
},
{
"created": "Fri, 12 Oct 2018 15:15:52 GMT",
"version": "v5"
}
] | 2018-12-05 | [
[
"Lesourd",
"Martin",
""
]
] | The interior of the Kerr solution is singular and achronological. The classic singularity theorem by Hawking and Penrose relies on chronology, and thus does not apply to the Kerr solution. An improvement of their theorem by Kriele partially removes the requirement of chronology. However, both of these singularity theorems fail to give any information on the type or location of the incomplete geodesics. Here, using recent results of Minguzzi, we prove a new singularity theorem, specifically designed to apply to black holes, which enables locating null incomplete geodesics within the black hole interior, all the while allowing certain forms of chronology violation in the interior. |
0807.4596 | Farook Rahaman | F. Rahaman, M. Kalam and K. A. Rahman | Wormhole geometry from real feasible matter sources | 7 pages, 3 figures. To appear in Int.J.Theor.Phys | Int.J.Theor.Phys.48:471-475,2009 | 10.1007/s10773-008-9822-y | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide a prescription of real feasible sources that supply fuel to
construct a traversable wormhole. A class of exact solutions for
Einstein-Maxwell field equations describing wormhole with an anisotropic matter
distribution has been presented. The anisotropy plays a crucial role for the
existence of the spacetime comprising wormhole geometry.
| [
{
"created": "Tue, 29 Jul 2008 08:39:11 GMT",
"version": "v1"
}
] | 2009-02-18 | [
[
"Rahaman",
"F.",
""
],
[
"Kalam",
"M.",
""
],
[
"Rahman",
"K. A.",
""
]
] | We provide a prescription of real feasible sources that supply fuel to construct a traversable wormhole. A class of exact solutions for Einstein-Maxwell field equations describing wormhole with an anisotropic matter distribution has been presented. The anisotropy plays a crucial role for the existence of the spacetime comprising wormhole geometry. |
1810.05540 | Rodrigo Maier | Rodrigo Maier and Ivano Dami\~ao Soares | Curvature Late-Time Acceleration in an Eternal Universe | 8 pages, 6 figures. arXiv admin note: text overlap with
arXiv:1710.06911 | null | 10.1088/1475-7516/2018/12/029 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct a FLRW universe considering an anisotropic scaling between space
and time at extremely high and low energies only. In this context, Friedmann
equations contain an additional term arising from spatial curvature which
implements nonsingular bounces in the early Universe. The matter content of the
model is a nonrelativistic pressureless perfect fluid and radiation. By
breaking covariance diffeomorphism also at extreme large scales, an additional
term furnishes late-time acceleration due to spatial curvature so that a
cosmological constant is not needed. In order to probe the final fate of the
universe we also introduce a lower order curvature term which dominates in deep
IR. Given the observational parameters we obtain a concrete model in eternal
recurrence in which the end of late-time acceleration takes place at a redshift
$z \simeq -0.14$ and the universe recollapses at $z\simeq - 0.32$.
| [
{
"created": "Thu, 11 Oct 2018 13:54:10 GMT",
"version": "v1"
}
] | 2018-12-26 | [
[
"Maier",
"Rodrigo",
""
],
[
"Soares",
"Ivano Damião",
""
]
] | We construct a FLRW universe considering an anisotropic scaling between space and time at extremely high and low energies only. In this context, Friedmann equations contain an additional term arising from spatial curvature which implements nonsingular bounces in the early Universe. The matter content of the model is a nonrelativistic pressureless perfect fluid and radiation. By breaking covariance diffeomorphism also at extreme large scales, an additional term furnishes late-time acceleration due to spatial curvature so that a cosmological constant is not needed. In order to probe the final fate of the universe we also introduce a lower order curvature term which dominates in deep IR. Given the observational parameters we obtain a concrete model in eternal recurrence in which the end of late-time acceleration takes place at a redshift $z \simeq -0.14$ and the universe recollapses at $z\simeq - 0.32$. |
1105.2023 | Kostiantyn Ropotenko | Kostiantyn Ropotenko | Rotational terms and quantum degeneracy in black holes | 8 pages, no figures | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | It is believed that the first law of black-hole mechanics has no independent
physical significance and acquires it only after identifying with the first law
of thermodynamics. It is argued here that the first law of black-hole mechanics
has a direct physical significance: not only the term $\Omega dJ$ but all its
terms have the same mechanical meaning - the rotational kinetic energy of a
black hole in real or in an internal space. Moreover, it is shown that the
Kerr-Newman black hole is a system of non-degenerate plane rotators represented
by the corresponding terms in the first law of black-hole mechanics. It is
found that a degeneracy arises because the energy of a black hole does not
depend on where an internal angular momentum of a black hole associated with
the black hole area is determined on the horizon.
| [
{
"created": "Tue, 10 May 2011 19:14:47 GMT",
"version": "v1"
}
] | 2011-05-11 | [
[
"Ropotenko",
"Kostiantyn",
""
]
] | It is believed that the first law of black-hole mechanics has no independent physical significance and acquires it only after identifying with the first law of thermodynamics. It is argued here that the first law of black-hole mechanics has a direct physical significance: not only the term $\Omega dJ$ but all its terms have the same mechanical meaning - the rotational kinetic energy of a black hole in real or in an internal space. Moreover, it is shown that the Kerr-Newman black hole is a system of non-degenerate plane rotators represented by the corresponding terms in the first law of black-hole mechanics. It is found that a degeneracy arises because the energy of a black hole does not depend on where an internal angular momentum of a black hole associated with the black hole area is determined on the horizon. |
gr-qc/0510049 | Paul Langlois | Paul Langlois | Causal particle detectors and topology | 47 pages, 9 figures | Annals Phys. 321 (2006) 2027-2070 | 10.1016/j.aop.2006.01.013 | null | gr-qc | null | We investigate particle detector responses in some topologically non-trivial
spacetimes. We extend a recently proposed regularization of the massless scalar
field Wightman function in 4-dimensional Minkowski space to arbitrary
dimension, to the massive scalar field, to quotients of Minkowski space under
discrete isometry groups and to the massless Dirac field. We investigate in
detail the transition rate of inertial and uniformly accelerated detectors on
the quotient spaces under groups generated by $(t,x,y,z)\mapsto(t,x,y,z+2a)$,
$(t,x,y,z)\mapsto(t,-x,y,z)$, $(t,x,y,z)\mapsto(t,-x,-y,z)$,
$(t,x,y,z)\mapsto(t,-x,-y,z+a)$ and some higher dimensional generalizations.
For motions in at constant $y$ and $z$ on the latter three spaces the response
is time dependent. We also discuss the response of static detectors on the RP^3
geon and inertial detectors on RP^3 de Sitter space via their associated global
embedding Minkowski spaces (GEMS). The response on RP^3 de Sitter space, found
both directly and in its GEMS, provides support for the validity of applying
the GEMS procedure to detector responses and to quotient spaces such as RP^3 de
Sitter space and the RP^3 geon where the embedding spaces are Minkowski spaces
with suitable identifications.
| [
{
"created": "Mon, 10 Oct 2005 15:10:48 GMT",
"version": "v1"
}
] | 2009-11-11 | [
[
"Langlois",
"Paul",
""
]
] | We investigate particle detector responses in some topologically non-trivial spacetimes. We extend a recently proposed regularization of the massless scalar field Wightman function in 4-dimensional Minkowski space to arbitrary dimension, to the massive scalar field, to quotients of Minkowski space under discrete isometry groups and to the massless Dirac field. We investigate in detail the transition rate of inertial and uniformly accelerated detectors on the quotient spaces under groups generated by $(t,x,y,z)\mapsto(t,x,y,z+2a)$, $(t,x,y,z)\mapsto(t,-x,y,z)$, $(t,x,y,z)\mapsto(t,-x,-y,z)$, $(t,x,y,z)\mapsto(t,-x,-y,z+a)$ and some higher dimensional generalizations. For motions in at constant $y$ and $z$ on the latter three spaces the response is time dependent. We also discuss the response of static detectors on the RP^3 geon and inertial detectors on RP^3 de Sitter space via their associated global embedding Minkowski spaces (GEMS). The response on RP^3 de Sitter space, found both directly and in its GEMS, provides support for the validity of applying the GEMS procedure to detector responses and to quotient spaces such as RP^3 de Sitter space and the RP^3 geon where the embedding spaces are Minkowski spaces with suitable identifications. |
2403.15537 | Leonardo Giuliano Trombetta | Eugeny Babichev, Ignacy Sawicki, Leonardo G. Trombetta | The cosmic trimmer: Black-hole hair in scalar-Gauss-Bonnet gravity is
altered by cosmology | 6 pages | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Static black holes in general relativity modified by a linear scalar coupling
to the Gauss-Bonnet invariant always carry hair. We show that the same
mechanism that creates the hair makes it incompatible with a cosmological
horizon. Other scalar-tensor models do not have this problem when
time-dependence of the scalar provides a natural matching to cosmology.
Scalar-Gauss-Bonnet is particularly rigid and such a scenario does not help. An
extra operator makes the theory behave like the other models and the
cosmological horizon can be accommodated. The hair, however, is drastically
altered.
| [
{
"created": "Fri, 22 Mar 2024 18:00:01 GMT",
"version": "v1"
}
] | 2024-04-02 | [
[
"Babichev",
"Eugeny",
""
],
[
"Sawicki",
"Ignacy",
""
],
[
"Trombetta",
"Leonardo G.",
""
]
] | Static black holes in general relativity modified by a linear scalar coupling to the Gauss-Bonnet invariant always carry hair. We show that the same mechanism that creates the hair makes it incompatible with a cosmological horizon. Other scalar-tensor models do not have this problem when time-dependence of the scalar provides a natural matching to cosmology. Scalar-Gauss-Bonnet is particularly rigid and such a scenario does not help. An extra operator makes the theory behave like the other models and the cosmological horizon can be accommodated. The hair, however, is drastically altered. |
2209.10374 | Zhi-Zhang Peng | Zhi-Zhang Peng, Zhen-Min Zeng, Chengjie Fu, Zong-Kuan Guo | Generation of gravitational waves in dynamical Chern-Simons gravity | null | Phys. Rev. D 106, 124044 (2022) | 10.1103/PhysRevD.106.124044 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate gravitational waves (GWs) generated in a two-field
inflationary model with a non-canonical kinetic term, in which the
gravitational Chern-Simons term is coupled to a heavy dynamical field. In such
a model, primordial GWs experience a period of resonant amplification for some
modes. In addition, isocurvature perturbations suffer from a temporary
tachyonic instability due to an effective negative mass, which source curvature
perturbations, resulting in large induced GWs. These two stochastic
gravitational wave backgrounds correspond to different frequency bands, which
are expected to be detected by future GW detectors such as SKA, LISA and Taiji.
| [
{
"created": "Wed, 21 Sep 2022 14:11:28 GMT",
"version": "v1"
}
] | 2023-01-11 | [
[
"Peng",
"Zhi-Zhang",
""
],
[
"Zeng",
"Zhen-Min",
""
],
[
"Fu",
"Chengjie",
""
],
[
"Guo",
"Zong-Kuan",
""
]
] | We investigate gravitational waves (GWs) generated in a two-field inflationary model with a non-canonical kinetic term, in which the gravitational Chern-Simons term is coupled to a heavy dynamical field. In such a model, primordial GWs experience a period of resonant amplification for some modes. In addition, isocurvature perturbations suffer from a temporary tachyonic instability due to an effective negative mass, which source curvature perturbations, resulting in large induced GWs. These two stochastic gravitational wave backgrounds correspond to different frequency bands, which are expected to be detected by future GW detectors such as SKA, LISA and Taiji. |
1805.09577 | Francisco Jos\'e Maldonado Torralba | J.A.R. Cembranos, J. Gigante Valcarcel, F.J. Maldonado Torralba | Fermion dynamics in torsion theories | 17 pages, 2 figures, minor changes, conclusions unchanged. It matches
the version published in JCAP | JCAP04(2019)039 | 10.1088/1475-7516/2019/04/039 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we have studied the non-geodesical behaviour of particles with
spin 1/2 in Poincar\'e gauge theories of gravity, via the WKB method and the
Mathisson-Papapetrou equation. We have analysed the relation between the two
approaches and we have argued the different advantages associated with the WKB
approximation. Within this approach, we have calculated the trajectories in a
particular Poincar\'e gauge theory, discussing the viability of measuring such
a motion.
| [
{
"created": "Thu, 24 May 2018 09:49:00 GMT",
"version": "v1"
},
{
"created": "Thu, 14 Jun 2018 09:55:36 GMT",
"version": "v2"
},
{
"created": "Tue, 4 Jun 2019 16:07:44 GMT",
"version": "v3"
}
] | 2019-06-05 | [
[
"Cembranos",
"J. A. R.",
""
],
[
"Valcarcel",
"J. Gigante",
""
],
[
"Torralba",
"F. J. Maldonado",
""
]
] | In this work we have studied the non-geodesical behaviour of particles with spin 1/2 in Poincar\'e gauge theories of gravity, via the WKB method and the Mathisson-Papapetrou equation. We have analysed the relation between the two approaches and we have argued the different advantages associated with the WKB approximation. Within this approach, we have calculated the trajectories in a particular Poincar\'e gauge theory, discussing the viability of measuring such a motion. |
gr-qc/0009036 | Bernhard Haisch | Bernard Haisch, Alfonso Rueda and York Dobyns | Inertial mass and the quantum vacuum fields | Annalen der Physik, in press | Annalen Phys.10:393-414,2001 | 10.1002/1521-3889(200105)10:5<393::AID-ANDP393>3.0.CO;2-Z | null | gr-qc | null | Even when the Higgs particle is finally detected, it will continue to be a
legitimate question to ask whether the inertia of matter as a reaction force
opposing acceleration is an intrinsic or extrinsic property of matter. General
relativity specifies which geodesic path a free particle will follow, but
geometrodynamics has no mechanism for generating a reaction force for deviation
from geodesic motion. We discuss a different approach involving the
electromagnetic zero-point field (ZPF) of the quantum vacuum. It has been found
that certain asymmetries arise in the ZPF as perceived from an accelerating
reference frame. In such a frame the Poynting vector and momentum flux of the
ZPF become non-zero. Scattering of this quantum radiation by the quarks and
electrons in matter can result in an acceleration-dependent reaction force.
Both the ordinary and the relativistic forms of Newton's second law, the
equation of motion, can be derived from the electrodynamics of such
ZPF-particle interactions. Conjectural arguments are given why this interaction
should take place in a resonance at the Compton frequency, and how this could
simultaneously provide a physical basis for the de Broglie wavelength of a
moving particle. This affords a suggestive perspective on a deep connection
between electrodynamics, the origin of inertia and the quantum wave nature of
matter.
| [
{
"created": "Tue, 12 Sep 2000 19:29:40 GMT",
"version": "v1"
}
] | 2017-09-27 | [
[
"Haisch",
"Bernard",
""
],
[
"Rueda",
"Alfonso",
""
],
[
"Dobyns",
"York",
""
]
] | Even when the Higgs particle is finally detected, it will continue to be a legitimate question to ask whether the inertia of matter as a reaction force opposing acceleration is an intrinsic or extrinsic property of matter. General relativity specifies which geodesic path a free particle will follow, but geometrodynamics has no mechanism for generating a reaction force for deviation from geodesic motion. We discuss a different approach involving the electromagnetic zero-point field (ZPF) of the quantum vacuum. It has been found that certain asymmetries arise in the ZPF as perceived from an accelerating reference frame. In such a frame the Poynting vector and momentum flux of the ZPF become non-zero. Scattering of this quantum radiation by the quarks and electrons in matter can result in an acceleration-dependent reaction force. Both the ordinary and the relativistic forms of Newton's second law, the equation of motion, can be derived from the electrodynamics of such ZPF-particle interactions. Conjectural arguments are given why this interaction should take place in a resonance at the Compton frequency, and how this could simultaneously provide a physical basis for the de Broglie wavelength of a moving particle. This affords a suggestive perspective on a deep connection between electrodynamics, the origin of inertia and the quantum wave nature of matter. |
2012.13526 | Masato Minamitsuji | Masato Minamitsuji | Disformal transformation of stationary and axisymmetric solutions in
modified gravity | 33 pages, 4 figures, published version | Phys. Rev. D102, 124017(2020) | 10.1103/PhysRevD.102.124017 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The extended scalar-tensor and vector-tensor theories admit black hole
solutions with the nontrivial profiles of the scalar and vector fields,
respectively. The disformal transformation maps a solution in a class of the
scalar-tensor or vector-tensor theories to that in another class, and hence it
can be a useful tool to construct a new nontrivial solution from the known one.
First, we investigate how the stationary and axisymmetric solutions in the
vector-tensor theories without and with the $U(1)$ gauge symmetry are
disformally transformed. We start from a stationary and axisymmetric solution
satisfying the circularity conditions, and show that in both the cases the
metric of the disformed solution in general does not satisfy the circularity
conditions. Using the fact that a solution in a class of the vector-tensor
theories with the vanishing field strength is mapped to that in a class of the
shift-symmetric scalar-tensor theories, we derive the disformed stationary and
axisymmetric solutions in a class of these theories, and show that the metric
of the disformed solutions does not satisfy the circularity conditions if the
scalar field depends on the time or azimuthal coordinate. We also confirm that
in the scalar-tensor theories without the shift symmetry, the disformed
stationary and axisymmetric solutions satisfy the circularity conditions.
Second, we investigate the disformal transformations of the stationary and
axisymmetric black hole solutions in the generalized Proca theory with the
nonminimal coupling to the Einstein tensor, the shift-symmetric scalar-tensor
theory with the nonminimal derivative coupling to the Einstein tensor, the
Einstein-Maxwell theory, and the Einstein-conformally coupled scalar field
theory. We show that the disformal transformations modify the causal properties
of the spacetime.
| [
{
"created": "Fri, 25 Dec 2020 06:28:14 GMT",
"version": "v1"
}
] | 2020-12-29 | [
[
"Minamitsuji",
"Masato",
""
]
] | The extended scalar-tensor and vector-tensor theories admit black hole solutions with the nontrivial profiles of the scalar and vector fields, respectively. The disformal transformation maps a solution in a class of the scalar-tensor or vector-tensor theories to that in another class, and hence it can be a useful tool to construct a new nontrivial solution from the known one. First, we investigate how the stationary and axisymmetric solutions in the vector-tensor theories without and with the $U(1)$ gauge symmetry are disformally transformed. We start from a stationary and axisymmetric solution satisfying the circularity conditions, and show that in both the cases the metric of the disformed solution in general does not satisfy the circularity conditions. Using the fact that a solution in a class of the vector-tensor theories with the vanishing field strength is mapped to that in a class of the shift-symmetric scalar-tensor theories, we derive the disformed stationary and axisymmetric solutions in a class of these theories, and show that the metric of the disformed solutions does not satisfy the circularity conditions if the scalar field depends on the time or azimuthal coordinate. We also confirm that in the scalar-tensor theories without the shift symmetry, the disformed stationary and axisymmetric solutions satisfy the circularity conditions. Second, we investigate the disformal transformations of the stationary and axisymmetric black hole solutions in the generalized Proca theory with the nonminimal coupling to the Einstein tensor, the shift-symmetric scalar-tensor theory with the nonminimal derivative coupling to the Einstein tensor, the Einstein-Maxwell theory, and the Einstein-conformally coupled scalar field theory. We show that the disformal transformations modify the causal properties of the spacetime. |
gr-qc/0001041 | George Lavrelashvili | Arsen Khvedelidze, George Lavrelashvili, Takahiro Tanaka | On cosmological perturbations in FRW model with scalar field and false
vacuum decay | 4 p., Revtex. No changes in the text. Accepted for publication in
Phys. Rev. D | Phys.Rev. D62 (2000) 083501 | 10.1103/PhysRevD.62.083501 | OU-TAP 117, YITP-00-16 | gr-qc | null | The unconstrained reduced action corresponding to the dynamics of scalar
fluctuations about the Friedmann-Robertson-Walker (FRW) background is derived
using Dirac's method of description of singular Lagrangian systems. The results
are applied to so-called negative mode problem in description of tunneling
transitions with gravity. With our special choice of physical variable, the
kinetic term of the reduced action has a conventional signature for a wide
class of models. In this representation, the existence of a negative mode
justifying the false vacuum decay picture turns out to be manifest. We also
explain how the present result becomes consistent with the previously proved
``no negative mode (supercritical supercurvature mode) theorem''.
| [
{
"created": "Sat, 15 Jan 2000 05:58:30 GMT",
"version": "v1"
},
{
"created": "Sat, 8 Apr 2000 20:22:48 GMT",
"version": "v2"
},
{
"created": "Wed, 23 Aug 2000 08:09:56 GMT",
"version": "v3"
}
] | 2009-10-31 | [
[
"Khvedelidze",
"Arsen",
""
],
[
"Lavrelashvili",
"George",
""
],
[
"Tanaka",
"Takahiro",
""
]
] | The unconstrained reduced action corresponding to the dynamics of scalar fluctuations about the Friedmann-Robertson-Walker (FRW) background is derived using Dirac's method of description of singular Lagrangian systems. The results are applied to so-called negative mode problem in description of tunneling transitions with gravity. With our special choice of physical variable, the kinetic term of the reduced action has a conventional signature for a wide class of models. In this representation, the existence of a negative mode justifying the false vacuum decay picture turns out to be manifest. We also explain how the present result becomes consistent with the previously proved ``no negative mode (supercritical supercurvature mode) theorem''. |
1502.05922 | Valeri Vardanyan | Valeri Vardanyan, Luca Amendola (ITP, University of Heidelberg,
Germany) | How can we tell whether dark energy is composed by multiple fields? | v2: 12 pages, no figures, minor changes, references added | Phys. Rev. D 92, 024009 (2015) | 10.1103/PhysRevD.92.024009 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Dark energy is often assumed to be composed by a single scalar field. The
background cosmic expansion is not sufficient to determine whether this is true
or not. We study multi-field scalar-tensor models with a general dark matter
source and write the observable modified gravity parameters (effective
gravitational constant and anisotropic stress) in the form of a ratio of
polynomials in the Fourier wavenumber k of order 2N, where N is the number of
scalar fields. By comparing these observables to real data it is in principle
possible to determine the number of dark energy scalar fields coupled to
gravity. We also show that there are no realistic non-trivial cases in which
the order of the polynomials is reduced.
| [
{
"created": "Fri, 20 Feb 2015 16:27:46 GMT",
"version": "v1"
},
{
"created": "Thu, 21 May 2015 14:44:18 GMT",
"version": "v2"
}
] | 2015-07-15 | [
[
"Vardanyan",
"Valeri",
"",
"ITP, University of Heidelberg,\n Germany"
],
[
"Amendola",
"Luca",
"",
"ITP, University of Heidelberg,\n Germany"
]
] | Dark energy is often assumed to be composed by a single scalar field. The background cosmic expansion is not sufficient to determine whether this is true or not. We study multi-field scalar-tensor models with a general dark matter source and write the observable modified gravity parameters (effective gravitational constant and anisotropic stress) in the form of a ratio of polynomials in the Fourier wavenumber k of order 2N, where N is the number of scalar fields. By comparing these observables to real data it is in principle possible to determine the number of dark energy scalar fields coupled to gravity. We also show that there are no realistic non-trivial cases in which the order of the polynomials is reduced. |
2107.05470 | Gabriel R. Bengochea | Gabriel Le\'on, Gabriel R. Bengochea | Enlightening the CSL model landscape in inflation | 18 pages, 2 Appendices. Improved version, accepted in EPJC | Eur. Phys. J. C 81, 1055 (2021) | 10.1140/epjc/s10052-021-09851-w | null | gr-qc astro-ph.CO quant-ph | http://creativecommons.org/licenses/by/4.0/ | We propose a novel realization for the natural extrapolation of the
continuous spontaneous localization (CSL) model, in order to account for the
origin of primordial inhomogeneities during inflation. This particular model is
based on three main elements: (i) the semiclassical gravity framework, (ii) a
collapse-generating operator associated to a relativistic invariant scalar of
the energy-momentum tensor, and (iii) an extension of the CSL parameter(s) as a
function of the spacetime curvature. Furthermore, employing standard
cosmological perturbation theory at linear order, and for a reasonable range
within the parameter space of the model, we obtain a nearly scale invariant
power spectrum consistent with recent observational CMB data. This opens a vast
landscape of different options for the application of the CSL model to the
cosmological context, and possibly sheds light on searches for a full covariant
version of the CSL theory.
| [
{
"created": "Mon, 12 Jul 2021 14:37:02 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Dec 2021 13:33:38 GMT",
"version": "v2"
}
] | 2021-12-07 | [
[
"León",
"Gabriel",
""
],
[
"Bengochea",
"Gabriel R.",
""
]
] | We propose a novel realization for the natural extrapolation of the continuous spontaneous localization (CSL) model, in order to account for the origin of primordial inhomogeneities during inflation. This particular model is based on three main elements: (i) the semiclassical gravity framework, (ii) a collapse-generating operator associated to a relativistic invariant scalar of the energy-momentum tensor, and (iii) an extension of the CSL parameter(s) as a function of the spacetime curvature. Furthermore, employing standard cosmological perturbation theory at linear order, and for a reasonable range within the parameter space of the model, we obtain a nearly scale invariant power spectrum consistent with recent observational CMB data. This opens a vast landscape of different options for the application of the CSL model to the cosmological context, and possibly sheds light on searches for a full covariant version of the CSL theory. |
gr-qc/9904018 | Yongsung Yoon | Yongsung Yoon | Conformally Coupled Induced Gravity with Gradient Torsion | 8pages, LaTeX, no figure, to be appeared in PRD | Phys.Rev. D59 (1999) 127501 | 10.1103/PhysRevD.59.127501 | null | gr-qc | null | It is found that conformally coupled induced gravity with gradient torsion
gives a dilaton gravity in Riemann geometry. In the Einstein frame of the
dilaton gravity the conformal symmetry is hidden and a non-vanishing
cosmological constant is not plausible due to the constraint of the conformal
coupling.
| [
{
"created": "Wed, 7 Apr 1999 09:22:02 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Yoon",
"Yongsung",
""
]
] | It is found that conformally coupled induced gravity with gradient torsion gives a dilaton gravity in Riemann geometry. In the Einstein frame of the dilaton gravity the conformal symmetry is hidden and a non-vanishing cosmological constant is not plausible due to the constraint of the conformal coupling. |
1802.02764 | Sven Zschocke | Sven Zschocke | Light propagation in 2PN approximation in the field of one moving
monopole: I. Initial value problem | 53 pages, 1 figure | Classical and Quantum Gravity 35 (2018) 055013 | 10.1088/1361-6382/aa9976 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this investigation the light propagation in the gravitational field of one
arbitrarily moving body with monopole structure is considered in the second
post-Newtonian approximation. It is found that the light trajectory depends on
the acceleration of the body. Some of these acceleration terms are important in
order to get well-defined logarithmic functions with dimensionless arguments,
while all the other acceleration terms are negligible on the pico-second level
of accuracy in time-delay measurements. The expressions of the observables
total light deflection and time delay are determined.
| [
{
"created": "Thu, 8 Feb 2018 09:24:53 GMT",
"version": "v1"
}
] | 2018-02-09 | [
[
"Zschocke",
"Sven",
""
]
] | In this investigation the light propagation in the gravitational field of one arbitrarily moving body with monopole structure is considered in the second post-Newtonian approximation. It is found that the light trajectory depends on the acceleration of the body. Some of these acceleration terms are important in order to get well-defined logarithmic functions with dimensionless arguments, while all the other acceleration terms are negligible on the pico-second level of accuracy in time-delay measurements. The expressions of the observables total light deflection and time delay are determined. |
1501.00428 | Farook Rahaman | A. Sepehri, Farook Rahaman, Anirudh Pradhan and Iftikar Hossain Sardar | Emergence and Expansion of Cosmic Space in BIonic system | Published in Phys.Lett. B741 (2014) 92-96 | Phys.Lett. B741 (2014) 92-96 | 10.1016/j.physletb.2014.12.030 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recently, Padmanabhan [arXiv:1206.4916] argued that the expansion rate of the
universe can be thought of as the emergence of space as cosmic time progresses
and is related to the difference between the surface degrees of freedom on the
holographic horizon and the bulk degrees of freedom inside. The main question
arises as to what is origin of emergence of space in 4D universe? We answer to
this question in BIonic system. The BIon is a configuration in flat space of a
D-brane and a parallel anti-D-brane connected by a thin shell wormhole with
F-string charge. We propose a new model that allows all degrees of freedom
inside and outside the universe are controlled by the evolutions of BIon in
extra dimension and tend to degrees of freedom of black F-string in string
theory or black M2-brane in M theory.
| [
{
"created": "Thu, 11 Dec 2014 14:58:59 GMT",
"version": "v1"
},
{
"created": "Wed, 7 Jan 2015 13:09:27 GMT",
"version": "v2"
}
] | 2015-01-08 | [
[
"Sepehri",
"A.",
""
],
[
"Rahaman",
"Farook",
""
],
[
"Pradhan",
"Anirudh",
""
],
[
"Sardar",
"Iftikar Hossain",
""
]
] | Recently, Padmanabhan [arXiv:1206.4916] argued that the expansion rate of the universe can be thought of as the emergence of space as cosmic time progresses and is related to the difference between the surface degrees of freedom on the holographic horizon and the bulk degrees of freedom inside. The main question arises as to what is origin of emergence of space in 4D universe? We answer to this question in BIonic system. The BIon is a configuration in flat space of a D-brane and a parallel anti-D-brane connected by a thin shell wormhole with F-string charge. We propose a new model that allows all degrees of freedom inside and outside the universe are controlled by the evolutions of BIon in extra dimension and tend to degrees of freedom of black F-string in string theory or black M2-brane in M theory. |
1608.07314 | Suddhasattwa Brahma | Jibril Ben Achour, Suddhasattwa Brahma, Antonino Marciano | Spherically symmetric sector of self dual Ashtekar gravity coupled to
matter: Anomaly-free algebra of constraints with holonomy corrections | 22 pages, few references added | Phys. Rev. D 96, 026002 (2017) | 10.1103/PhysRevD.96.026002 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using self dual Ashtekar variables, we investigate (at the effective level)
the spherically symmetry reduced model of loop quantum gravity, both in vacuum
and when coupled to a scalar field. Within the real Ashtekar-Barbero
formulation, the system scalar field coupled to spherically symmetric gravity
is known to possess a non closed (quantum) algebra of constraints once the
holonomy corrections are introduced, which forbids the loop quantization of the
model. Moreover, the vacuum case, while not anomalous, introduces modifications
which are usually interpreted as an effective signature change of the metric in
the deep quantum region. We show in this paper that both those complications
disappear when working with self dual Ashtekar variables, both in the vacuum
case and in the case of gravity minimally coupled to a scalar field. In this
framework, the algebra of the holonomy corrected constraints is anomaly free
and reproduces the classical hypersurface deformation algebra without any
deformations. A possible path towards quantization of this model is briefly
discussed.
| [
{
"created": "Thu, 25 Aug 2016 21:31:23 GMT",
"version": "v1"
},
{
"created": "Mon, 24 Oct 2016 15:09:24 GMT",
"version": "v2"
}
] | 2017-07-12 | [
[
"Achour",
"Jibril Ben",
""
],
[
"Brahma",
"Suddhasattwa",
""
],
[
"Marciano",
"Antonino",
""
]
] | Using self dual Ashtekar variables, we investigate (at the effective level) the spherically symmetry reduced model of loop quantum gravity, both in vacuum and when coupled to a scalar field. Within the real Ashtekar-Barbero formulation, the system scalar field coupled to spherically symmetric gravity is known to possess a non closed (quantum) algebra of constraints once the holonomy corrections are introduced, which forbids the loop quantization of the model. Moreover, the vacuum case, while not anomalous, introduces modifications which are usually interpreted as an effective signature change of the metric in the deep quantum region. We show in this paper that both those complications disappear when working with self dual Ashtekar variables, both in the vacuum case and in the case of gravity minimally coupled to a scalar field. In this framework, the algebra of the holonomy corrected constraints is anomaly free and reproduces the classical hypersurface deformation algebra without any deformations. A possible path towards quantization of this model is briefly discussed. |
1611.05878 | Astrid Eichhorn | Astrid Eichhorn, Stefan Lippoldt | Quantum gravity and Standard-Model-like fermions | 6 pages, 2 figures | null | 10.1016/j.physletb.2017.01.064 | null | gr-qc hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We discover that chiral symmetry does not act as an infrared attractor of the
renormalization group flow under the impact of quantum gravity fluctuations.
Thus, observationally viable quantum gravity models must respect chiral
symmetry. In our truncation, asymptotically safe gravity does, as a chiral
fixed point exists. A second non-chiral fixed point with massive fermions
provides a template for models with dark matter. This fixed point disappears
for more than 10 fermions, suggesting that an asymptotically safe ultraviolet
completion for the standard model plus gravity enforces chiral symmetry.
| [
{
"created": "Thu, 17 Nov 2016 21:00:06 GMT",
"version": "v1"
}
] | 2017-02-08 | [
[
"Eichhorn",
"Astrid",
""
],
[
"Lippoldt",
"Stefan",
""
]
] | We discover that chiral symmetry does not act as an infrared attractor of the renormalization group flow under the impact of quantum gravity fluctuations. Thus, observationally viable quantum gravity models must respect chiral symmetry. In our truncation, asymptotically safe gravity does, as a chiral fixed point exists. A second non-chiral fixed point with massive fermions provides a template for models with dark matter. This fixed point disappears for more than 10 fermions, suggesting that an asymptotically safe ultraviolet completion for the standard model plus gravity enforces chiral symmetry. |
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